Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/06/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1049 AM MST MON MAR 4 2013
.UPDATE...
&&
.SHORT TERM...PRETTY GOOD BATCH OF SHOWERS DROPPING OUT OF SE
WYOMING WILL MOVE ACROSS THE FRONT RANGE CITIES THIS AFTERNOON.
WEBCAMS SHOW WIDESPREAD LIGHT SNOW ACROSS SE WYOMING THOUGH
CEILINGS HAVE STAYED FAIRLY HIGH. SOME OF THE SHOWERS HAVE
PRODUCED BURSTS OF HEAVY SNOW BUT NOT FOR LONG. EXPECT THIS SAME
WEATHER WILL BE OUR AFTERNOON WEATHER. SUBSTANTIALLY RAISED
POPS...BUT STILL EXPECTED AMOUNTS TO BE UNDER TWO INCHES WITH WET
ROADS IN GENERAL...SOME SLUSHING IN THE HEAVIER SHOWERS. PROSPECT
FOR A FOCUSED PROLONGED SNOW BAND DOES NOT LOOK VERY GOOD AND LOW
LEVELS ARE DEFINITELY DRYING BY LATE AFTERNOON...SO AMOUNTS ON THE
PALMER DIVIDE MAY BE OVERDONE. MOST OF THIS ACTIVITY WILL BE EAST
OF THE MOUNTAINS...SO I WILL GO AHEAD AND LET THE MOUNTAIN
ADVISORIES EXPIRE.
&&
.AVIATION...SNOW SHOWERS EXPECTED BETWEEN 19Z AND 01Z. MVFR
CEILINGS WITH AREAS OF IFR IN THE HEAVIER SHOWERS...BUT ANY HEAVY
SHOWERS SHOULD BE SHORT LIVED. CONDITIONS SHOULD IMPROVE
CONSIDERABLY BETWEEN 00Z AND 03Z WITH VISUAL APPROACHES TO KDEN
AFTER THAT TIME. ACCUMULATIONS UNDER TWO INCHES WITH SOME MELTING
ON THE RUNWAYS.
&&
.PREV DISCUSSION... /ISSUED 411 AM MST MON MAR 4 2013/
SHORT TERM...DIFFICULT FORECAST TODAY. CURRENT SURFACE ANALYSIS
SHOWS COLD FRONT HAS PUSHED INTO THE DENVER METRO AREA. THIS FRONT
IS QUITE SHALLOW...BUT WILL PROVIDE COOLING AND ENOUGH UPSLOPE FOR
POTENTIAL STRATUS AND A FEW LIGHT SNOW SHOWERS THIS MORNING.
HOWEVER...MID/UPPER LEVELS WERE BEGINNING TO SHOW SOME SIGNS OF
DRYING FROM THE NORTH...AS RADAR SHOWS SNOW IN THE NORTHERN FRONT
RANGE MOUNTAINS DECREASING. MEANWHILE...SUMMIT COUNTY CAMS AND
RADAR SHOWS GOOD SNOW CONTINUING IN THE I-70 MOUNTAIN CORRIDOR
WITH POOR TRAVEL CONDITIONS. GJT RADAR SHOWS ANOTHER BATCH OF
HIGHER RETURNS TO PUSH INTO THAT EARLY EARLY THIS MORNING BEFORE A
DECREASE OCCURS LATER. WILL LET THE MOUNTAIN ADVISORIES CONTINUE
TIL NOON. POSSIBLE EXTENSION OF ADVISORIES MAY BE REQUIRED WITH
NEXT SHORT WAVE/SPEED MAX THIS AFTERNOON.
THIS NEXT UPPER LEVEL WAVE CREATES MOST OF THE CHALLENGE WITH
TODAYS FORECAST. CURRENT UPPER LEVEL ANALYSIS SHOWS THIS FEATURE
DROPPING ACROSS IDAHO WITH ENHANCED CLOUDINESS ON THE POLEWARD
SIDE. THIS FEATURE WILL REACH NORTHERN COLORADO THIS AFTERNOON. AT
THE SAME TIME...SOME DEEPENING OF THE UPSLOPE FLOW WILL LIKELY
OCCUR WITH ANOTHER ANTICYCLONIC SURGE FROM THE NORTH. AT THIS
TIME...THIS SHOT OF UPSLOPE APPEARS TO BE SHORT LIVED...BUT ENOUGH
TO PRODUCE SNOW SHOWERS ALONG THE FRONT RANGE AND SOUTH/SOUTHEAST
ACROSS THE PALMER DIVIDE TO LINCOLN COUNTY. THIS COULD PLAY HAVOC
WITH THE AFTERNOON RUSH WITH A QUICK INCH OF SNOW POSSIBLE...BUT
ROADS TEMPS ARE EXPECTED TO BE WARM ENOUGH TO MELT MOST SNOW THAT
FALLS...IF IT SNOWS. WE DO THINK WITH THE QUICK SHOT OF
UPSLOPE...FAVORABLE SURFACE Q-G VERTICAL MOTION...AND APPROACH OF
UPPER LEVEL SPEED MAX...ENOUGH FACTORS WARRANT AN INCREASE IN POPS
TO LIKELY FOR THE DENVER METRO AND POINTS SOUTH AND EAST THIS
AFTERNOON. WITH STRONG GUSTY NORTHERLY WINDS...WILL ADD AREAS OF
BLOWING SNOW TO THE FORECAST AS WELL EAST/SOUTHEAST OF DENVER. AN
ADVISORY MAY BE NEEDED FOR THOSE LOCATIONS DUE TO COMBINATION OF
GUSTY WINDS AND HIGHER PROBABILITY OF SNOW...WILL CONTINUE TO
MONITOR.
THINGS DRY OUT RATHER QUICKLY FROM NORTH TO SOUTH THIS EVENING
WITH CLEARING SKIES OVERNIGHT. TEMPERATURES WILL BE COLD
ESPECIALLY WHERE WINDS DECREASE SUFFICIENTLY.
LONG TERM...AN UPPER LEVEL RIDGE WILL BE OVER THE AREA ON TUE
WITH DRY WLY FLOW ALOFT. TEMPS WILL MODERATE SOME WITH READINGS
IN THE MID TO UPPER 40S ACROSS NERN CO. FOR WED THE FLOW ALOFT
WILL BECOME MORE SWLY AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE
WRN US. SOME MID AND HIGH LEVEL MOISTURE WILL MOVE ACROSS BUT
OUTSIDE OF SOME CLOUDS IT SHOULD REMAIN DRY. 850-700 TEMPS WOULD
SUPPORT HIGHS IN THE 50S TO NR 60 OVER NERN CO.
FOR THU THE UPPER LEVEL TROUGH WILL INTENSIFY OVER THE WRN US WITH
SWLY FLOW CONTINUING. ONCE AGAIN SOME MID AND HIGH LEVEL MOISTURE
WILL BE EMBEDDED IN THE FLOW HOWEVER OUTSIDE OF A SLIGHT CHC OF
-SHSN WEST OF THE DIVIDE MAINLY IN ZN 31 IT LOOKS DRY. HIGHS WILL
REMAIN MILD ONCE AGAIN OVER NERN CO WITH READINGS IN THE MID 50S
TO LOWER 60S. BY FRI AN UPPER LEVEL STORM SYSTEM WILL DEVELOP OVER
SRN CALIFORNIA WITH SSW FLOW ALOFT. BOTH THE GFS AND ECMWF SHOW AN
INCREASE IN MOISTURE HOWEVER WITH SSW FLOW AT 700 MB BEST SHOT OF
SNOW WILL STAY WEST OF THE DIVIDE. EAST OF THE MTNS A CDFNT WILL
TRY TO BACKDOOR INTO NERN CO DURING THE DAY AS SFC LOW PRES DVLPS
OVER SRN CO. AT THIS TIME WILL DROP HIGHS BACK INTO THE 40S ACROSS
NERN CO. CROSS-SECTIONS REALLY DO NOT SHOW THAT MUCH MOISTURE IN
THE LOWER LEVELS THRU FRI AFTN SO WILL ONLY MENTION A SLIGHT CHC
OF SHOWERS IN AND NR THE FOOTHILLS.
BY THE WEEKEND THERE ARE MAJOR DIFFERENCES BETWEEN THE GFS AND
ECMWF MODELS WITH REGARDS TO HANDLING OF THE UPPER LEVEL STORM
SYSTEM OVER SRN CALIFORNIA. THE GFS SHOWS A SIGNIFICANT PIECE OF
ENERGY LIFTING ENE OUT OF THE MAIN LOW AND TRACKS IT ACROSS NERN
CO BY SAT NIGHT WHILE THE UPPER LEVEL LOW MOVES INTO SRN ARIZONA.
MEANWHILE THE GFS SHOWS A SECONDARY SURGE OF COLDER AIR MOVING
INTO NERN CO FRI NIGHT INTO SAT WITH INCREASING UPSLOPE FLOW AS
THE PIECE OF ENERGY MOVES ACROSS LEADING TO A GOOD CHANCE OF PCPN FRI
NIGHT THRU SAT AFTN ESPECIALLY EAST OF THE DIVIDE ACROSS THE
PLAINS. FCST THICKNESSES SUGGEST MOST OF THE PCPN WOULD FALL AS
SNOW OVER NERN CO WITH SEVERAL INCHES POSSIBLE. BY SAT NIGHT INTO
SUN THE SECOND PIECE OF ENERGY OVER SRN ARIZONA MOVES EAST ACROSS
SRN NEW MEXICO AS MUCH DRIER AIR SPREADS ACROSS NRN CO. THUS THIS
WOULD LEAD TO LITTLE ADDITIONAL PCPN SAT NIGHT THRU SUN.
MEANWHILE THE ECMWF...GEM AND EVEN SEVERAL OF THE GFS ENSEMBLE
MEMBERS SHOW THE UPPER LEVEL LOW OVER SRN CALIFORNIA REMAINING AS
COMPACT SYSTEM AND MOVING ENE INTO SRN COLORADO/NRN NEW MEXICO BY
SAT NIGHT AND THEN INTENSIFYING OVER ERN CO/WRN KANSAS BY SUN
MORNING. BASED ON THIS SOLUTION THE BEST CHC OF PCPN WOULD BE FM
SAT AFTN INTO SUN ACROSS NRN CO WITH STILL SEVERAL INCHES OF SNOW
POSSIBLE HOWEVER IT WOULD BE DELAYED ROUGHLY 18 HOURS VS WHAT THE
OPERATIONAL GFS IS SHOWING. OVERALL THE ECMWF HAS BEEN VERY
CONSISTENT SHOWING THIS STORM SYSTEM AFFECTING NRN CO FOR THE LAST
4 DAYS WHILE THE GFS HAS HAD A PLETHORA OF DIFFERENT SOLUTIONS. AT
THIS POINT SINCE THE TIMING OF THE SYSTEM IS STILL SOMEWHAT
CERTAIN WILL KEEP POPS IN THE CHC CATEGORY FM FRI NIGHT THRU SUN
UNTIL IT BECOMES MORE CLEAR ON WHEN THE BEST CHC OF PCPN WILL
OCCUR.
AVIATION...DIFFICULT FORECAST WITH REGARD TO STRATUS THIS MORNING
AND BETTER CHANCE OF SNOW THIS AFTERNOON. WITH SUFFICIENT BUT VERY
SHALLOW UPSLOPE AND CLOSE T/TD SPREADS EARLY THIS MORNING...WE
WOULD EXPECT A STRATUS DECK NEAR 1000-1500 FT AGL TO DEVELOP IN
THE EARLY MORNING HOURS...BUT QUITE A BIT OF UNCERTAINTY AS KCYS
REPORTED A 300 FOOT CEILING EARLIER ONLY TO HAVE IT
DISSIPATE...AND THEN REFORM AGAIN NEAR 1000 FT AGL. BY 16Z-18Z...
COULD SEE SNOW SHOWERS BEGIN TO DEVELOP IN THE AREA BUT BEST
CHANCE PER LATEST HRRR AND RAP SUGGEST 20Z- 23Z FOR MAIN THREAT.
COULD SEE VSBYS BRIEFLY DROP TO ONE HALF MILE IN A HEAVIER SNOW
SHOWER WITH A QUICK INCH OF SNOW. MOST LIKELY SCENARIO IS FOR A
DUSTING TO LESS THAN 1 INCH...BUT A CHANCE OF 1-2 INCH SNOW
BETWEEN 20Z AND 23Z. BY 00Z-02Z ALL SNOW SHOULD BE OUT OF THE AREA
WITH CLEARING SKIES. NORTH/NORTHEAST WINDS TODAY SHOULD GUST TO
BETWEEN 25 AND 30 KTS...WITH STRONGEST WINDS BEFORE 14Z AND THEN
AGAIN AFTER NEXT FRONTAL PUSH 19Z-21Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR COZ031-033-034.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....RPK
AVIATION/UPDATE...GIMMESTAD
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
411 AM MST MON MAR 4 2013
.SHORT TERM...DIFFICULT FORECAST TODAY. CURRENT SURFACE ANALYSIS
SHOWS COLD FRONT HAS PUSHED INTO THE DENVER METRO AREA. THIS FRONT
IS QUITE SHALLOW...BUT WILL PROVIDE COOLING AND ENOUGH UPSLOPE FOR
POTENTIAL STRATUS AND A FEW LIGHT SNOW SHOWERS THIS MORNING.
HOWEVER...MID/UPPER LEVELS WERE BEGINNING TO SHOW SOME SIGNS OF
DRYING FROM THE NORTH...AS RADAR SHOWS SNOW IN THE NORTHERN FRONT
RANGE MOUNTAINS DECREASING. MEANWHILE...SUMMIT COUNTY CAMS AND
RADAR SHOWS GOOD SNOW CONTINUING IN THE I-70 MOUNTAIN CORRIDOR
WITH POOR TRAVEL CONDITIONS. GJT RADAR SHOWS ANOTHER BATCH OF
HIGHER RETURNS TO PUSH INTO THAT EARLY EARLY THIS MORNING BEFORE A
DECREASE OCCURS LATER. WILL LET THE MOUNTAIN ADVISORIES CONTINUE
TIL NOON. POSSIBLE EXTENSION OF ADVISORIES MAY BE REQUIRED WITH
NEXT SHORT WAVE/SPEED MAX THIS AFTERNOON.
THIS NEXT UPPER LEVEL WAVE CREATES MOST OF THE CHALLENGE WITH
TODAYS FORECAST. CURRENT UPPER LEVEL ANALYSIS SHOWS THIS FEATURE
DROPPING ACROSS IDAHO WITH ENHANCED CLOUDINESS ON THE POLEWARD
SIDE. THIS FEATURE WILL REACH NORTHERN COLORADO THIS AFTERNOON. AT
THE SAME TIME...SOME DEEPENING OF THE UPSLOPE FLOW WILL LIKELY
OCCUR WITH ANOTHER ANTICYCLONIC SURGE FROM THE NORTH. AT THIS
TIME...THIS SHOT OF UPSLOPE APPEARS TO BE SHORT LIVED...BUT ENOUGH
TO PRODUCE SNOW SHOWERS ALONG THE FRONT RANGE AND SOUTH/SOUTHEAST
ACROSS THE PALMER DIVIDE TO LINCOLN COUNTY. THIS COULD PLAY HAVOC
WITH THE AFTERNOON RUSH WITH A QUICK INCH OF SNOW POSSIBLE...BUT
ROADS TEMPS ARE EXPECTED TO BE WARM ENOUGH TO MELT MOST SNOW THAT
FALLS...IF IT SNOWS. WE DO THINK WITH THE QUICK SHOT OF
UPSLOPE...FAVORABLE SURFACE Q-G VERTICAL MOTION...AND APPROACH OF
UPPER LEVEL SPEED MAX...ENOUGH FACTORS WARRANT AN INCREASE IN POPS
TO LIKELY FOR THE DENVER METRO AND POINTS SOUTH AND EAST THIS
AFTERNOON. WITH STRONG GUSTY NORTHERLY WINDS...WILL ADD AREAS OF
BLOWING SNOW TO THE FORECAST AS WELL EAST/SOUTHEAST OF DENVER. AN
ADVISORY MAY BE NEEDED FOR THOSE LOCATIONS DUE TO COMBINATION OF
GUSTY WINDS AND HIGHER PROBABILITY OF SNOW...WILL CONTINUE TO
MONITOR.
THINGS DRY OUT RATHER QUICKLY FROM NORTH TO SOUTH THIS EVENING
WITH CLEARING SKIES OVERNIGHT. TEMPERATURES WILL BE COLD
ESPECIALLY WHERE WINDS DECREASE SUFFICIENTLY.
.LONG TERM...AN UPPER LEVEL RIDGE WILL BE OVER THE AREA ON TUE
WITH DRY WLY FLOW ALOFT. TEMPS WILL MODERATE SOME WITH READINGS
IN THE MID TO UPPER 40S ACROSS NERN CO. FOR WED THE FLOW ALOFT
WILL BECOME MORE SWLY AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE
WRN US. SOME MID AND HIGH LEVEL MOISTURE WILL MOVE ACROSS BUT
OUTSIDE OF SOME CLOUDS IT SHOULD REMAIN DRY. 850-700 TEMPS WOULD
SUPPORT HIGHS IN THE 50S TO NR 60 OVER NERN CO.
FOR THU THE UPPER LEVEL TROUGH WILL INTENSIFY OVER THE WRN US WITH
SWLY FLOW CONTINUING. ONCE AGAIN SOME MID AND HIGH LEVEL MOISTURE
WILL BE EMBEDDED IN THE FLOW HOWEVER OUTSIDE OF A SLIGHT CHC OF
-SHSN WEST OF THE DIVIDE MAINLY IN ZN 31 IT LOOKS DRY. HIGHS WILL
REMAIN MILD ONCE AGAIN OVER NERN CO WITH READINGS IN THE MID 50S
TO LOWER 60S. BY FRI AN UPPER LEVEL STORM SYSTEM WILL DEVELOP OVER
SRN CALIFORNIA WITH SSW FLOW ALOFT. BOTH THE GFS AND ECMWF SHOW AN
INCREASE IN MOISTURE HOWEVER WITH SSW FLOW AT 700 MB BEST SHOT OF
SNOW WILL STAY WEST OF THE DIVIDE. EAST OF THE MTNS A CDFNT WILL
TRY TO BACKDOOR INTO NERN CO DURING THE DAY AS SFC LOW PRES DVLPS
OVER SRN CO. AT THIS TIME WILL DROP HIGHS BACK INTO THE 40S ACROSS
NERN CO. CROSS-SECTIONS REALLY DO NOT SHOW THAT MUCH MOISTURE IN
THE LOWER LEVELS THRU FRI AFTN SO WILL ONLY MENTION A SLIGHT CHC
OF SHOWERS IN AND NR THE FOOTHILLS.
BY THE WEEKEND THERE ARE MAJOR DIFFERENCES BETWEEN THE GFS AND
ECMWF MODELS WITH REGARDS TO HANDLING OF THE UPPER LEVEL STORM
SYSTEM OVER SRN CALIFORNIA. THE GFS SHOWS A SIGNIFICANT PIECE OF
ENERGY LIFTING ENE OUT OF THE MAIN LOW AND TRACKS IT ACROSS NERN
CO BY SAT NIGHT WHILE THE UPPER LEVEL LOW MOVES INTO SRN ARIZONA.
MEANWHILE THE GFS SHOWS A SECONDARY SURGE OF COLDER AIR MOVING
INTO NERN CO FRI NIGHT INTO SAT WITH INCREASING UPSLOPE FLOW AS
THE PIECE OF ENERGY MOVES ACROSS LEADING TO A GOOD CHANCE OF PCPN FRI
NIGHT THRU SAT AFTN ESPECIALLY EAST OF THE DIVIDE ACROSS THE
PLAINS. FCST THICKNESSES SUGGEST MOST OF THE PCPN WOULD FALL AS
SNOW OVER NERN CO WITH SEVERAL INCHES POSSIBLE. BY SAT NIGHT INTO
SUN THE SECOND PIECE OF ENERGY OVER SRN ARIZONA MOVES EAST ACROSS
SRN NEW MEXICO AS MUCH DRIER AIR SPREADS ACROSS NRN CO. THUS THIS
WOULD LEAD TO LITTLE ADDITIONAL PCPN SAT NIGHT THRU SUN.
MEANWHILE THE ECMWF...GEM AND EVEN SEVERAL OF THE GFS ENSEMBLE
MEMBERS SHOW THE UPPER LEVEL LOW OVER SRN CALIFORNIA REMAINING AS
COMPACT SYSTEM AND MOVING ENE INTO SRN COLORADO/NRN NEW MEXICO BY
SAT NIGHT AND THEN INTENSIFYING OVER ERN CO/WRN KANSAS BY SUN
MORNING. BASED ON THIS SOLUTION THE BEST CHC OF PCPN WOULD BE FM
SAT AFTN INTO SUN ACROSS NRN CO WITH STILL SEVERAL INCHES OF SNOW
POSSIBLE HOWEVER IT WOULD BE DELAYED ROUGHLY 18 HOURS VS WHAT THE
OPERATIONAL GFS IS SHOWING. OVERALL THE ECMWF HAS BEEN VERY
CONSISTENT SHOWING THIS STORM SYSTEM AFFECTING NRN CO FOR THE LAST
4 DAYS WHILE THE GFS HAS HAD A PLETHORA OF DIFFERENT SOLUTIONS. AT
THIS POINT SINCE THE TIMING OF THE SYSTEM IS STILL SOMEWHAT
CERTAIN WILL KEEP POPS IN THE CHC CATEGORY FM FRI NIGHT THRU SUN
UNTIL IT BECOMES MORE CLEAR ON WHEN THE BEST CHC OF PCPN WILL
OCCUR.
&&
.AVIATION...DIFFICULT FORECAST WITH REGARD TO STRATUS THIS MORNING
AND BETTER CHANCE OF SNOW THIS AFTERNOON. WITH SUFFICIENT BUT VERY
SHALLOW UPSLOPE AND CLOSE T/TD SPREADS EARLY THIS MORNING...WE
WOULD EXPECT A STRATUS DECK NEAR 1000-1500 FT AGL TO DEVELOP IN
THE EARLY MORNING HOURS...BUT QUITE A BIT OF UNCERTAINTY AS KCYS
REPORTED A 300 FOOT CEILING EARLIER ONLY TO HAVE IT
DISSIPATE...AND THEN REFORM AGAIN NEAR 1000 FT AGL. BY 16Z-18Z...
COULD SEE SNOW SHOWERS BEGIN TO DEVELOP IN THE AREA BUT BEST
CHANCE PER LATEST HRRR AND RAP SUGGEST 20Z- 23Z FOR MAIN THREAT.
COULD SEE VSBYS BRIEFLY DROP TO ONE HALF MILE IN A HEAVIER SNOW
SHOWER WITH A QUICK INCH OF SNOW. MOST LIKELY SCENARIO IS FOR A
DUSTING TO LESS THAN 1 INCH...BUT A CHANCE OF 1-2 INCH SNOW
BETWEEN 20Z AND 23Z. BY 00Z-02Z ALL SNOW SHOULD BE OUT OF THE AREA
WITH CLEARING SKIES. NORTH/NORTHEAST WINDS TODAY SHOULD GUST TO
BETWEEN 25 AND 30 KTS...WITH STRONGEST WINDS BEFORE 14Z AND THEN
AGAIN AFTER NEXT FRONTAL PUSH 19Z-21Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR COZ031-033-034.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....RPK
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
917 PM EST TUE MAR 5 2013
.SYNOPSIS...
AN AREA OF LOW PRESSURE ENTERING WEST VIRGINIA WILL MOVE OFF THE
VIRGINIA COAST WEDNESDAY, DEVELOPING INTO A STRONG COASTAL STORM.
THE LOW WILL SLOWLY MOVE TO THE EAST THROUGH THE WEEK. HIGH
PRESSURE WILL BUILD OVER THE AREA SATURDAY INTO SUNDAY. EARLY NEXT
WEEK, ANOTHER STORM SYSTEM WILL BE ORGANIZING OVER THE CENTRAL
PLAINS AND IS EXPECTED TO AFFECT OUR AREA MONDAY INTO MONDAY
NIGHT.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
HOPING A RESEARCH PROJECT COMES OF THIS EVENT AS THERE ARE SO
MANY CONFLICTING SIGNALS STILL IN OUR CWA WE DONT KNOW WHERE TO
START. CAN UNDERSTAND WHY SPRING EQUATIONS ARE CAUSING PROBLEMS
WITH MOS GUIDANCE, BUT THE MODELS KEEPING SFC TEMPS WELL ABOVE
FREEZING INTO EARLY WED EVENING EXCEPT FOR THE WRF-NMMB WHICH
DYNAMIC COOLS TO NEAR FREEZING.
WELL AS FOR PCPN VERIFICATION THROUGH 00Z. ALL OF THE MODELS HAD A
GOOD HANDLE ON THE AREA PF EXCELLENT MID LEVEL QVEC CONVERGENCE
EMANATING FROM THE SFC LOW INTO IL. SINCE MOST OF THIS FELL AS
SNOW HARD TO SAY IF THEY WERE WET OR DRY, BUT THE PLACEMENT WAS
GOOD. WHERE IT WAS RAIN FARTHER TO THE SOUTH, THE CAN GGEM SEEMED
TO VERIFY THE BEST. A BUNCH OF MODELS WERE TOO WET IN SC AND GA,
DON`T KNOW IF THIS WAS JUST BEING TOO FAST WITH DEVELOPING
CONVECTION AS THE FRONT IS NOT SLOW AND THERE IS CONVECTION NOW.
THE MODELS ARE SLIGHTLY TOO SLOW WITH THE BACK EDGE, WRF-NMMB MOST
GUILTY PARTY. AS FOR THE SFC LOW ITSELF, THE 18Z WRF-NMMB VERIFIED
THE BEST. ALSO GOOD WITH BAGGINESS OVER WRN NC. ECMWF 2ND BEST,
CORRECT LATITUDE, JUST SLIGHTLY SLOW, NOTHING NEW THERE. 00Z RUC
NOT GOOD, SFC LOW IS NOT IN OH YET AS 01Z. CAN SEE A CIRCULATION
FORMING AROUND CLT AT 02Z. RAIN/SNOW LINE OUTSIDE OF THE MOUNTAINS
WAS AROUND 1295M 1000-850MB NAM THICKNESS.
AT 925MB IN THE LOCAL AREA ALL OF THE MODELS WERE TOO COLD, THE
WRF-NMMB 6HR FCST AMONG THE COLDEST SOMETIMES BY 2 OR 3C. GFS BEST
OVERALL. BOTH BWI AND PHL ACAR FREEZING LEVEL IS CURRENTLY 2500
FEET. THIS MAY ALL BE A MOOT POINT AS THERE IS PLENTY OF DRY AIR
BETWEEN 925MB AND SFC ON THE 00Z SOUNDINGS. IF ANYTHING, THE
MODELS TOO MOIST TOO FAST AT IAD LOOK GOOD AT WAL. AT 850MB
CONVERSELY THE MODELS ARE TOO WARM BY AROUND A DEGREE OR SO, THE
ECMWF OVERALL THE BEST. AT 500MB THERE IS MORE RIDGING OVER THE
CAROLINAS AND THE CLOSED LOW LOOKS TO BE DIGGING MORE. THE BNA
HEIGHT AND TEMPERATURE FORECASTS ARE LAGGING BEHIND.
THE LATEST SREF EMPHASIZING TWO AREAS AS BEST POTENTIAL FOR HEAVY
(WARNING CRITERIA) SNOW. ONE WHERE CURRENT WARNING IS IN EFFECT,
THE SECOND MAX MAY BE IN OCEAN AND MONMOUTH. SREF QPF IS
APPROXIMATELY 50 TO 75 PCT OF OPERATIONAL 18Z WRF-NMMB.
WOULD THINK THE 500MB FCST SHORTFALLS WOULD RESULT IN A SHARPER
TURN WITH THE 00Z MODEL RUN. AS FOR CHANGES WITH THIS SHORT TERM,
BASED ON THE PREV RUC AND HRRR, WE ADDED SOME MORE SNOW TO OUR
EASTERN SHORE OVERNIGHT. THE TOP DOWN PROCEDURE WE DID WITH THE
PREVIOUS UPDATE WAS ALL RAIN. LOOKS LIKE A SHOT OF SNOW FOR MAYBE
AN HOUR OR SO WHEN INTENSITY INCREASES LATER. ANY ADJUSTMENTS TO
TEMPERATURES WERE BASED ON CURRENT OBS. ITS COLDER TOWARD THE
COAST CURRENTLY THAN INLAND. WOULD THINK ONCE THE WINDS START AND
CLOUDS ARRIVE, THEY WILL BUMP UP.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
CONCERNS:
MOS WARM BIAS WITHIN THE CONSTANT PCPN SHIELD. APPLIED 2M 12Z/5 NAM
TEMPS FOR THIS PART OF THE FCST...IN PART BECAUSE OF THE CONSTANTLY
COLDER THERMAL PROFILES OFFERED BY THE NAM.
MODELS: 12Z/5 NAM...GFS AND UKMET ALL FURTHER SOUTH. STILL A VERY
LARGE STORM AND UNCERTAINTY REIGNS!
HEADLINES ARE POSTED AND THE GRIDDED TOOLS HAVE QUITE A MESS ON
OUR HANDS.
I AM CONCERNED WE MAY NEED WARNINGS WHERE ADVISORIES ARE NOW POSTED
IN SE PA BUT THE NEXT SHIFTS CAN REEVALUATE.
OTRW THE WATCHES WERE PUSHED BACK IN DE/MD SINCE THE BL LOOKS TOO
WARM TO PERMIT SNOW UNTIL VERY LATE IN THE AFTERNOON.
THE WARNING OF CHESTER AND CECIL COUNTIES HAS A BETTER CHANCE OF
MOSTLY SNOW DURING THE DAY WEDNESDAY BUT HOW MUCH ACCUMULATES IS
UNCERTAIN. WE COVERED FOR THE POSSIBILITY OF HEAVIER ACCUMULATIONS
BY 5PM.
IF YOU JUST LOOKED AT MASS FIELDS INCLUDING ENSEMBLED 850 TEMPS
AND LARGE SCALE FLOW...I`D BE CONCERNED ABOUT AT THE VERY LEAST
ELEVATION HEAVY SNOW OVER SOUTHEAST PA INTO CENTRAL AND NRN NJ AS
THE DAY EVOLVES (PRESUMING PCPN BEGINS IN NNJ DURING THE DAY).
EVEN PTYPE IS FAVORING ALL SNOW NW OF I95. IF ITS SNOW AND SFC
TEMPS IN THE MID 30S...THEN NOT MUCH PROBLEM DURING THE DAYLIGHT
HOURS. HOWEVER...IT DOES LOOK LIKE THERE WILL HAVE TO BE A PERIOD
OF MDT TO POSSIBLY HEAVY SNOW OVER SE PA WEDNESDAY. HOW MUCH ACCRETES
IS DEBATABLE BUT THESE KIND OF SITUATIONS FAVOR ELEVATIONS AND MAYBE
50 PERCENT ACCRETES ON PAVEMENT COMPARED TO ACCUMULATIONS ON ALL
OTHER ADJACENT SURFACES.
I95 SEWD...SHOULD BE MAINLY RAIN WITH I95 THE CORRIDOR WHERE OCNL
MIX OF SNOW RAIN OCCURS AS THE PCPN IS BRIEFLY HEAVIER AT TIMES.
POOR DRAINAGE STREET FLOODING ANTICIPATED FOR S NJ...DE AND E MD
DURING THE AFTN.
NE WINDS GUST 25-35 MPH WITH ISOLATED GUSTS 50-60 MPH ALONG THE
APPROXIMATELY THE NEAREST 10 MILES OF THE COAST.
THE WIND ADVISORY POSTED AGAINST THE COAST MAY NEED EXPANSION INTO
MUCH OF E MD...NORTHERN DE INTO MUCH OF I 95 CORRIDOR BY THE
ONCOMING MID SHIFT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
BY WEDNESDAY EVENING, THE LOW PRESSURE SYSTEM SHOULD BE MOVING OFF
OR ALREADY OFF THE MID-ATLANTIC COAST AND BEGINNING TO STRENGTHEN.
THE STORM WILL SLOWLY TRACK EASTWARD THROUGH WEDNESDAY NIGHT, INTO
THURSDAY AND FRIDAY. WE MAY STILL CONTINUE TO HAVE SOME EFFECTS FROM
THE STORM FOR A COUPLE OF DAYS AS THE STORM WILL BE SLOW TO MOVE;
HOWEVER, WEDNESDAY NIGHT IS THE MAIN PERIOD IN THE LONG TERM WHERE
THE BIGGEST CONCERN IS FOR NOW. THE STORM WILL FINALLY MOVE FURTHER
OUT TO SEA ON SATURDAY, LOSING ITS GRIP ON OUR AREA, FOLLOWED BY
HIGH PRESSURE FOR SATURDAY NIGH INTO SUNDAY. ANOTHER LOW PRESSURE
SYSTEM AND ASSOCIATED FRONTAL BOUNDARY IS EXPECTED TO AFFECT THE AREA
MONDAY INTO MONDAY NIGHT.
BY WEDNESDAY EVENING, PRECIPITATION SHOULD HAVE OVERSPREAD BASICALLY
OUR ENTIRE FORECAST AREA. THE 12Z MODEL GUIDANCE SUITE HAS SEVERAL
DIFFERENCES IN THE QPF AMOUNTS ACROSS THE AREA WITH THE NAM BEING ON
THE HIGHEST END, THE GFS ON THE LOWEST END, AND THE OTHERS SOMEWHERE
IN BETWEEN. WE FOLLOWED CLOSE TO HPC/WPC AND USED A BLEND OF THE
MODEL GUIDANCE. THIS GIVES US A QUARTER TO HALF INCH ACROSS OUR
COASTAL AND SOUTHERN AREAS, WITH A TENTH TO QUARTER ACROSS OUR
NORTHERN AREAS. THEN THE QUESTION BECOMES HOW MUCH SNOW FALLS AND
ACCUMULATES WITH THE AMOUNT OF QPF. OUR SNOWFALL FORECAST HAS
INCREASED A COUPLE OF INCHES FOR MANY AREAS. FOR THIS REASON WE HAVE
EXPANDED OUR WINTER STORM WATCH ACROSS PORTIONS OF SOUTHEASTERN
PENNSYLVANIA AND SOUTHERN NEW JERSEY WHERE SNOW AMOUNTS ARE NOW IN
THE 2-4 INCH RANGE FOR WEDNESDAY NIGHT. FOR AREAS OUTSIDE THE WATCH
AREA, BOTH NORTH AND SOUTH, WE ARE NOT CONFIDENT ENOUGH FOR SNOW
TOTALS TO GET CLOSE TO WARNING CRITERIA, SO WE WILL LET THE NEXT
SHIFTS TAKE A LOOK AT SUBSEQUENT MODEL GUIDANCE TO SEE IF ANY
FURTHER STATEMENTS ARE NEEDED.
WINDS WILL REMAIN GUSTY ACROSS THE AREA WEDNESDAY NIGHT, BUT SHOULD
BEGIN TO DIMINISH IN INTENSITY OVERNIGHT, SO THE HIGH WIND WARNING
WILL END AT 1 AM. NEVERTHELESS, WINDS COULD STILL GUST 35-45 MPH,
EVEN AFTER THE HIGH WIND WARNING ENDS.
AS WE GO INTO THURSDAY AND THURSDAY NIGHT, THE HEAVIEST
PRECIPITATION IS EXPECTED TO BE ENDING ACROSS MUCH OF OUR AREA.
HOWEVER, MODELS CONTINUE TO SHOW THAT SOME MOISTURE WILL CONTINUE TO
SWING BACK ACROSS OUR AREA ON THE WESTERN SIDE OF THE LOW PRESSURE
SYSTEM AS IT SLOWLY MOVES TO THE EAST. THIS WILL STILL KEEP A CHANCE
OF PRECIPITATION ACROSS A GOOD PORTION OF THE AREA, ESPECIALLY THE
NORTHERN HALF/TWO-THIRDS OF THE AREA. IT`S POSSIBLE WE COULD
CONTINUE TO SEE AND ADDITIONAL INCH OR SO OF SNOW ACROSS OUR
NORTHERN AREAS WHERE SNOW ACTUALLY CONTINUES. BY FRIDAY,
PRECIPITATION CHANCES CONTINUE TO DECREASE AS THE COASTAL LOW AND
ANY EFFECTS SHOULD BE WANING ACROSS THE AREA, AND END COMPLETELY BY
FRIDAY NIGHT.
HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE AREA FOR SATURDAY AND
SUNDAY, WHICH SHOULD PROVIDE FAIR WEATHER AND ABOVE NORMAL
TEMPERATURES. LATE IN THE DAY ON SUNDAY, A SHORT WAVE ALOFT IS
EXPECTED TO PASS NORTH OUR AREA WITH A BACKDOOR FRONT TRYING TO SAG
SOUTHWARD TOWARD OUR AREA. IT IS NOT EXPECTED THAT EITHER WILL PASS
OVER THE AREA, BUT MAY GET CLOSE ENOUGH TO INCREASE CLOUD COVER, AND
MAY BRING A SLIGHT CHANCE OF PRECIPITATION ACROSS THE NORTHERN HALF
OF THE CWA.
AN AREA OF LOW PRESSURE WILL BE MOVING OUT OF THE MID-MISSISSIPPI
VALLEY LATE SUNDAY AND INTO OUR AREA MONDAY INTO MONDAY NIGHT. THIS
BRINGS US OUT NEXT BEST CHANCE OF PRECIPITATION AS THE LOW MOVES TO
OUR NORTH AND THE ASSOCIATED FRONTAL BOUNDARY MOVES THROUGH THE
AREA. WITH THE CURRENT TRACK, MOST AREA WOULD BE RAIN, THROUGH
THERMAL SHOULD BECOME MORE APPARENT IN FUTURE FORECASTS.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
A RAPID TREND TO IFR OR NEAR IFR CONDITIONS TOWARD MORNING ALL
TERMINALS.
THIS EVENING GOOD VFR WITH LIGHT WINDS. OVERNIGHT A VFR CIG SHOULD
DEVELOP IN THE EASTERLY FLOW AND SNOW NW TERMINALS, RAIN AND SNOW
PHL CORRIDOR TERMINALS AND RAIN SERN TERMINALS FORECAST TO DEVELOP
TOWARD MORNING. TERMINALS WITH SOME SNOW SHOULD BE IFR AT LEAST BY
VSBYS, OTHERS MVFR. NORTHEAST TO EAST WINDS WILL BE INCREASING.
ON WEDNESDAY DAY IFR CONDITIONS IN SNOW EXPECTED FOR NORTHWEST
TERMINALS. PHL METRO AIRPORTS TRICKY AS A TRANSITION BACK AND
FORTH BETWEEN SNOW AND RAIN DRIVEN BY PCPN INTENSITY IS EXPECTED.
DURING SNOW CONDITIONS SHOULD BE IFR, RAIN THEY MIGHT BOUNCE UP TO
MVFR. SOUTHEAST TERMINALS SHOULD TREND TOWARD IFR CONDITIONS.
NORTHEAST WINDS SHOULD AVERAGE 15 TO 25 KTS WITH FREQUENT GUSTS
ABOVE 30KTS AT MOST AIRPORTS, EVEN HIGHER ALONG THE IMMEDIATE COAST.
A TRANSITION TO ALL SNOW WAS BROUGHT TO THE KPHL METRO AIRPORTS
LATE IN THE AFTERNOON AND EARLY IN THE EVENING. A BACKING OF THE
WINDS TOWARD THE NORTH WAS ALSO DEPICTED AT THE TERMINALS.
CONDITIONS MAY START IMPROVING AT FAR WESTERN AIRPORTS BY THEN
FLYING INTO KPHL...PCPN SHOULD BE ALL SNOW AOA 1000 FEET.
OUTLOOK...
WEDNESDAY NIGHT...MVFR/IFR CONDITIONS EXPECTED WITH A PERIOD OF
SNOW. STRONG WIND GUSTS 30-40 KNOTS EXPECTED.
THURSDAY-FRIDAY...POSSIBLE PERIODS OF MVFR WITH A CHANCE OF RAIN OR
SNOW. WIND GUSTS AROUND 20-25 KNOTS.
FRIDAY NIGHT-SATURDAY NIGHT...MOSTLY VFR EXPECTED.
&&
.MARINE...
WHAT WE THINK WE KNOW...GALE FOR SURE DEVELOPING EVERYWHERE BETWEEN
2 AM AND 7 AM WED. WE HEADLINED HIGHER PRECEDENCE STORM WARNING ALONG
MOST OF THE COAST FOR SCATTERED GUSTS 48-52 KNOTS. CONFIDENCE IS
NOT MORE THAN 80 PERCENT SINCE MODELS ARE STILL DIVERGENT ON SOLUTIONS.
GFS/NAM NE BOUNDARY LAYER WIND OF 45 TO 50 KNOTS SHOULD BE ENOUGH
TO DO THE TRICK FOR 2 TO 4 HOURS OF STORM FORCE GUSTS DURING THE
DAY WEDNESDAY...ESPECIALLY WITH SOME TRANSFER BELOW 975 MB.
I THINK THE SEAS WILL RUN SEVERAL FEET HIGHER THAN GUIDANCE AND HAVE
PARTIALLY RAISED THE 12Z/5 GFS WW NUMBERS.
OUTLOOK...
GALE TO STORM FORCE WINDS ARE EXPECTED TO CONTINUE ACROSS THE
ATLANTIC OCEAN WEDNESDAY NIGHT AS THE COASTAL LOW STRENGTHENS TO OUR
EAST. WINDS ALONG THE DELAWARE BAY SHOULD REMAIN GALE FORCE FOR
WEDNESDAY NIGHT. AS THE LOW SLOWLY MOVES TO OUR EAST, GALE FORCE
WINDS COULD REMAIN ACROSS THE COASTAL WATERS THROUGH FRIDAY AND
FRIDAY NIGHT. WIND WILL EVENTUALLY DROP TO SMALL CRAFT LEVELS
SATURDAY THEN BELOW ADVISORY LEVELS SATURDAY NIGHT INTO SUNDAY AS
HIGH PRESSURE BUILDS ACROSS THE AREA. HOWEVER, SEAS MAY REMAIN
ELEVATED THROUGH SUNDAY.
&&
.HYDROLOGY...
AT THIS TIME...WE ARE THINKING ONLY ADVISORIES FOR POOR DRAINAGE
STREET FLOODING.
&&
.TIDES/COASTAL FLOODING...
AN EAST TO SOUTHEAST FLOW HAD JUST BEGUN AS OF MID AFTERNOON TUESDAY
ALONG THE SOUTHERN HALF OF OUR ATLANTIC COAST AND UP DELAWARE BAY.
THAT FLOW WILL BECOME ESTABLISHED ALONG ALL NEW JERSEY AND DELAWARE
WATERS BY THIS EVENING, AND IT THEN WILL INTENSIFY FAIRLY QUICKLY BY
NOON WEDNESDAY AND SUBSEQUENTLY TAKE ITS TIME DIMINISHING AND
BACKING TO OFFSHORE. ALL THIS WILL BE DUE TO LOW PRESSURE MOVING OFF
THE COAST NEAR ORF EARLY WEDNESDAY AFTERNOON WHILE MODERATE HIGH
PRESSURE CENTERED OVER THE MISSISSIPPI RIVER VALLEY MAINTAINS A
TIGHT PRESSURE GRADIENT OVER US.
THE FACT THAT THE LOWER HIGH TIDE OCCURS WEDNESDAY AFTERNOON AND
EARLY EVENING COMBINED WITH THE SHORTER DURATION OF WINDS CONDUCIVE
TO COASTAL FLOODING BY THAT TIME LED US TO ACCEPT GUIDANCE
INDICATIONS (OFS, ESTOFS, MDL EXTRATROPICAL, AND LOCAL GUIDANCE)
THAT WIDESPREAD MINOR FLOODING IS THE MOST LIKELY OUTCOME THEN.
WE ARE MORE CONCERNED WITH THE LATE WEDNESDAY NIGHT/EARLY THURSDAY
HIGH TIDE, WHEN GUIDANCE PRETTY UNIFORMLY FORECASTS MODERATE TIDAL
FLOODING FOR RARITAN BAY AND ITS TIDAL TRIBUTARIES, THE ATLANTIC
COAST AND ADJACENT BACK BAYS INCLUDING BARNEGAT BAY, AND DELAWARE
BAY AND ITS TIDAL TRIBUTARIES (EXCEPT THE TIDAL DELAWARE RIVER). A
FEW NUMBERS COME OUT IN THE MAJOR RANGE. WE THEREFORE HAVE ISSUED A
WARNING THAT KEYS ON THE LATE WEDNESDAY NIGHT/EARLY THURSDAY HIGH
TIDE BUT THAT INCLUDES FORECASTS FOR THE PREVIOUS ONE.
WE ULTIMATELY MAY NEED TO ISSUE AT LEAST ADVISORIES FOR THE TIDAL
DELAWARE AND THE MARYLAND EASTERN SHORE, BUT WE DIDN`T SEE ANY
INDICATIONS OF MODERATE OR WORSE TIDAL FLOODING THERE THROUGH
DAYBREAK THURSDAY. THOSE BODIES MOST ALWAYS ARE LATEST TO RESPOND.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE
WEDNESDAY NIGHT FOR PAZ070-071-104-106.
WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 3 AM EST
THURSDAY FOR PAZ060-061-103-105.
WINTER STORM WARNING FROM 4 AM WEDNESDAY TO 3 AM EST THURSDAY
FOR PAZ101-102.
NJ...HIGH WIND WARNING FROM 7 AM WEDNESDAY TO 5 AM EST THURSDAY FOR
NJZ014-023>026.
COASTAL FLOOD WARNING FROM 1 AM TO 8 AM EST THURSDAY FOR
NJZ012>014-020>027.
WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE
WEDNESDAY NIGHT FOR NJZ016>022-025>027.
WIND ADVISORY FROM 7 AM TO 6 PM EST WEDNESDAY FOR NJZ013-
020>022-027.
DE...HIGH WIND WARNING FROM 7 AM WEDNESDAY TO 5 AM EST THURSDAY FOR
DEZ004.
COASTAL FLOOD WARNING FROM 1 AM TO 8 AM EST THURSDAY FOR
DEZ002>004.
WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE
WEDNESDAY NIGHT FOR DEZ001-002.
WIND ADVISORY FROM 7 AM TO 6 PM EST WEDNESDAY FOR DEZ002-003.
MD...WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE
WEDNESDAY NIGHT FOR MDZ012-015-019-020.
WINTER STORM WARNING FROM 4 AM WEDNESDAY TO 3 AM EST THURSDAY
FOR MDZ008.
MARINE...STORM WARNING FROM 6 AM WEDNESDAY TO 6 AM EST THURSDAY FOR
ANZ450>455.
GALE WARNING FROM 3 AM WEDNESDAY TO 6 AM EST THURSDAY FOR
ANZ430.
STORM WARNING FROM 6 AM TO 6 PM EST WEDNESDAY FOR ANZ431.
&&
$$
SYNOPSIS...ROBERTSON
NEAR TERM...GIGI
SHORT TERM...DRAG
LONG TERM...ROBERTSON
AVIATION...DRAG/ROBERTSON
MARINE...DRAG/ROBERTSON
HYDROLOGY...
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
400 AM EST MON MAR 4 2013
.DISCUSSION...
TODAY-TONIGHT...
HIGH PRESSURE BUILDING INTO THE AREA FROM THE GULF WITH THE CENTER
OVER EAST CENTRAL FLORIDA BY LATE AFTERNOON WITH CALMING WINDS. THIS
MORNING MARKS THE END OF THE CURRENT COLD SPELL AND ALTHOUGH
AFTERNOON HIGH TEMPERATURES WILL STILL BE ABOUT 10 DEGREES COOLER
THAN NORMAL TODAY...THEY`LL STILL BE SIGNIFICANTLY WARMER THAN THE
PAST COUPLE OF DAYS.
TEMPERATURES TONIGHT WILL REBOUND A BIT FROM THE PAST FEW NIGHTS BUT
STILL DROP INTO THE MID 30S TO 40S. WIND CHILLS WON`T BE A FACTOR
DUE TO THE LACK OF WIND WITH HIGH PRESSURE OVERHEAD.
TUE-WED...
THE H30-H20 JET PATTERN ACRS THE SRN CONUS HAS A STRONG ZONAL
COMPONENT THAT WILL MAINTAIN A PROGRESSIVE WX PATTERN THRU MIDWEEK.
THIS JET WILL ALLOW THE LARGE TROF OVER THE CENTRAL CONUS TO DEVELOP
INTO A POTENT STORM SYSTEM THAT WILL CRANK THE NEXT COLD FRONT THRU
CENTRAL FL TUE NIGHT INTO WED.
WHILE THIS FROPA WILL BRING THE NEXT BEST CHANCE FOR PRECIP TO
CENTRAL FL...AHEAD OF THE SYSTEM...AN H100-H70 ANTICYCLONE CENTERED
OVER THE WRN GOMEX WILL PUSH ACRS THE FL PENINSULA AND INTO THE WRN
ATLC BY DAYBREAK TUE. DEEP LYR W/NW FLOW WILL ACCOMPANY THE PASSAGE
OF THE RIDGE THAT WILL LIMIT THE WINDOW OF OPPORTUNITY FOR THE LCL
AIRMASS TO MOISTEN AHEAD OF THE ANTICIPATED FROPA.
THE AIRMASS OVER FL IS ALREADY QUITE ARID AS IS WITH EVENING
SOUNDINGS MEASURING A SCANT 0.2" PWAT OVER N FL...0.3" CENTRAL FL...
AND 0.5" S FL. WINDS WILL SHIFT TO THE S/SW ON TUE AS THE RIDGE
PUSHES INTO THE ATLC...BUT WITH RAP ANALYSIS INDICATING THE H100-H70
70PCT ISOHUME CLEAR DOWN IN THE SW CARIB...THE FRONT WILL ONLY HAVE
THE MOISTURE POOLING WITHIN ITS TROF TO WORK WITH. NEITHER GFS NOR
ECMWF INDICATES ANY SIG CHANGE IN THE SRN BRANCH OF THE JETSTREAM...
BOTH MAINTAIN THE CURRENT ZONAL ORIENTATION THRU THE END OF THE
WEEK.
POPS WITH THIS SYSTEM LOOK LIKE A CLASSIC "ONE AND DONE"...THOUGH
TIMING OF THE FROPA WILL HAVE THEM STRADDLE TUE NIGHT-WED MORNING
TIME FRAME. WARM W/SW FLOW TUE/TUE NIGHT WILL KEEP TEMPS NEAR AVG.
COLD AIR ADVECTION BEHIND THE FRONT ON WED AS WINDS SHIFT TO THE NW.
MAX TEMPS DIPPING INTO THE M60S/L70S (5-10F BLO AVG)...MIN TEMPS WED
NIGHT IN THE U30S/L40S (10-15F BLO AVG). FROST POTENTIAL WED NIGHT
INTO THU LOOKS LOW AS PGRAD SHOULD REMAIN TIGHT ENOUGH TO PREVENT
DECOUPLING.
THU-SUN...
A LARGE CONTINENTAL RIDGE WILL PUSH ACRS THE ERN HALF OF THE CONUS
THRU THE LATTER HALF OF THE WEEK...GENERATING AN EXTENDED PD OF NRLY
WINDS FOR CENTRAL FL. WINDS WILL GRADUALLY VEER FROM NW ON THU...TO
N ON FRI...THEN NE ON SAT. COOL/DRY AIR ADVECTION WILL RESULT...
KEEPING THE FCST DRY WITH MAX/MIN TEMPS ARND 5-10F BLO AVG THRU
FRI...ARND 5F BLO AVG SAT. BY SUN...ONSHORE FLOW WILL HAVE BEEN IN
PLACE LONG ENOUGH TO ALLOW TEMPS TO RECOVER TO NEAR AVG...BUT
AIRMASS EXPECTED TO REMAIN FAR TOO DRY TO INCLUDE ANY MEANINGFUL
CHANCE OF PRECIP ATTM.
&&
.AVIATION...
VFR WITH WINDS STARTING OUT OF THE NORTHWEST BUT BECOMING LIGHT AND
VARIABLE BY EVENING WITH HIGH PRESSURE OVERHEAD.
&&
.MARINE...
TODAY-TONIGHT...WINDS AND SEAS WILL DIMINISH THIS AFTERNOON WITH
HIGH PRESSURE MOVING INTO THE AREA. ALTHOUGH THE DAY BEGINS WITH A
SMALL CRAFT ADVISORY IN EFFECT FOR THE OFFSHORE ZONES...WINDS WILL
BE NEAR CALM WITH WAVE HEIGHTS OF ONLY 2-4 FEET BY TONIGHT.
TUE-TUE NIGHT...LIGHT TO GENTLE SRLY BREEZE TUE MORNING WILL FRESHEN
OUT OF THE SW AS A HIGH PRES RIDGE PUSHES ACRS FL AND INTO THE W
ATLC. WINDS BCMG W 15-20KTS NEARSHORE...20-25KTS OFFSHORE IN THE
PREDAWN HRS. OFFSHORE COMPONENT WILL LIMIT SEA HEIGHTS TO 2-3FT
NEARSHORE...OFFSHORE SEAS BUILDING FROM 2-3FT IN THE MORNING TO
4-6FT OVERNIGHT.
WED/WED NIGHT...HAZARDOUS BOATING CONDITIONS ANTICIPATED AS
SFC/BNDRY LYR WINDS SHIFT TO A FRESH NW BREEZE BEHIND A FAST MOVING
COLD FRONT. SEAS BUILDING TO 4-5FT NEARSHORE...6-8FT OFFSHORE
THU-FRI...WINDS WILL GRADUALLY DIMINISH AND VEER TO THE N THRU THE
END OF THE WEEK AS A LARGE POST FRONTAL HIGH PRES RIDGE BUILDS ACRS
THE SE CONUS. OVERALL BOATING CONDITIONS EXPECTED TO REMAIN MARGINAL
AT BEST...HOWEVER...AS A MODERATE TO FRESH NRLY BREEZE WILL GENERATE
ROUGH CONDITIONS ACRS THE LCL ATLC...ESPECIALLY IN THE GULF STREAM.
SEAS 3-4FT NEARSHORE AND 4-6FT OFFSHORE.
&&
.FIRE WX...
TODAY-TONIGHT...ANOTHER DRY DAY IS IN STORE BUT AN ONSHORE WIND
COMPONENT AT THE COAST THIS AFTERNOON WILL MEAN THAT CRITICAL RH
VALUES WILL BE LIMITED TO INLAND AREAS. IN ADDITION...WINDS WILL BE
LIGHTER TODAY AT ONLY AROUND 5 MPH COINCIDING WITH THE LOWEST RH
VALUES.
TUE-WED...SFC/TRANSPORT WINDS WILL SHIFT FROM SW ON TUE TO NW ON WED
AS A FAST MOVING COLD FRONT PUSHES THRU CENTRAL FL. AN ALREADY ARID
AIRMASS WILL HAVE LIMITED TIME TO MODIFY AHEAD OF THE FROPA. WHILE
SFC WINDS ON TUE NOT EXPECTED TO EXCEED 15 MPH...ANTICIPATE THE WARM
ADVECTION WILL ALLOW MIN RH VALUES TO FALL BLO 35PCT FOR 6-8HRS OVER
MOST OF EAST CENTRAL FL. BREEZY NW WINDS WED WITH LIMITED PRECIP...
TOTAL QPF BLO 0.10" AREAWIDE. DRY AIR ADVECTION BEHIND THE FRONT
WILL PUSH MIN RH VALUES BLO 35PCT FOR 4-6HRS FOR MOST AREAS W OF
I-95.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 62 42 73 55 / 0 0 0 30
MCO 66 43 76 58 / 0 0 0 20
MLB 63 42 75 59 / 0 0 0 20
VRB 63 40 76 58 / 0 0 0 20
LEE 65 44 75 56 / 0 0 0 30
SFB 65 43 75 57 / 0 0 0 20
ORL 65 46 75 58 / 0 0 0 20
FPR 64 42 75 59 / 0 0 0 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WARNING UNTIL 8 AM EST THIS MORNING FOR COASTAL VOLUSIA-
INLAND VOLUSIA-NORTHERN LAKE-SOUTHERN LAKE.
AM...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR WATERS
FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60
NM OFFSHORE-WATERS FROM SEBASTIAN INLET TO JUPITER INLET 20
TO 60 NM OFFSHORE-WATERS FROM VOLUSIA BREVARD COUNTY LINE
TO SEBASTIAN INLET 20 TO 60 NM OFFSHORE.
&&
$$
SHORT TERM/AVIATION...BOWEN
LONG TERM/IMPACT WX...BRAGAW
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
333 AM EST MON MAR 4 2013
.DISCUSSION...
TODAY-TONIGHT...
HIGH PRESSURE BUILDING INTO THE AREA FROM THE GULF WITH THE CENTER
OVER EAST CENTRAL FLORIDA BY LATE AFTERNOON WITH CALMING WINDS. THIS
MORNING MARKS THE END OF THE CURRENT COLD SPELL AND ALTHOUGH
AFTERNOON HIGH TEMPERATURES WILL STILL BE ABOUT 10 DEGREES COOLER
THAN NORMAL TODAY...THEY`LL STILL BE SIGNIFICANTLY WARMER THAN THE
PAST COUPLE OF DAYS.
TEMPERATURES TONIGHT WILL REBOUND A BIT FROM THE PAST FEW NIGHTS BUT
STILL DROP INTO THE MID 30S TO 40S. WIND CHILLS WON`T BE A FACTOR
DUE TO THE LACK OF WIND WITH HIGH PRESSURE OVERHEAD.
TUE-WED...
THE H30-H20 JET PATTERN ACRS THE SRN CONUS HAS A STRONG ZONAL
COMPONENT THAT WILL MAINTAIN A PROGRESSIVE WX PATTERN THRU MIDWEEK.
THIS JET WILL ALLOW THE LARGE TROF OVER THE CENTRAL CONUS TO DEVELOP
INTO A POTENT STORM SYSTEM THAT WILL CRANK THE NEXT COLD FRONT THRU
CENTRAL FL TUE NIGHT INTO WED.
WHILE THIS FROPA WILL BRING THE NEXT BEST CHANCE FOR PRECIP TO
CENTRAL FL...AHEAD OF THE SYSTEM...AN H100-H70 ANTICYCLONE CENTERED
OVER THE WRN GOMEX WILL PUSH ACRS THE FL PENINSULA AND INTO THE WRN
ATLC BY DAYBREAK TUE. DEEP LYR W/NW FLOW WILL ACCOMPANY THE PASSAGE
OF THE RIDGE THAT WILL LIMIT THE WINDOW OF OPPORTUNITY FOR THE LCL
AIRMASS TO MOISTEN AHEAD OF THE ANTICIPATED FROPA.
THE AIRMASS OVER FL IS ALREADY QUITE ARID AS IS WITH EVENING
SOUNDINGS MEASURING A SCANT 0.2" PWAT OVER N FL...0.3" CENTRAL FL...
AND 0.5" S FL. WINDS WILL SHIFT TO THE S/SW ON TUE AS THE RIDGE
PUSHES INTO THE ATLC...BUT WITH RAP ANALYSIS INDICATING THE H100-H70
70PCT ISOHUME CLEAR DOWN IN THE SW CARIB...THE FRONT WILL ONLY HAVE
THE MOISTURE POOLING WITHIN ITS TROF TO WORK WITH. NEITHER GFS NOR
ECMWF INDICATES ANY SIG CHANGE IN THE SRN BRANCH OF THE JETSTREAM...
BOTH MAINTAIN THE CURRENT ZONAL ORIENTATION THRU THE END OF THE
WEEK.
POPS WITH THIS SYSTEM LOOK LIKE A CLASSIC "ONE AND DONE"...THOUGH
TIMING OF THE FROPA WILL HAVE THEM STRADDLE TUE NIGHT-WED MORNING
TIME FRAME. WARM W/SW FLOW TUE/TUE NIGHT WILL KEEP TEMPS NEAR AVG.
COLD AIR ADVECTION BEHIND THE FRONT ON WED AS WINDS SHIFT TO THE NW.
MAX TEMPS DIPPING INTO THE M60S/L70S (5-10F BLO AVG)...MIN TEMPS WED
NIGHT IN THE U30S/L40S (10-15F BLO AVG). FROST POTENTIAL WED NIGHT
INTO THU LOOKS LOW AS PGRAD SHOULD REMAIN TIGHT ENOUGH TO PREVENT
DECOUPLING.
THU-SUN...
UPDATE TO FOLLOW.
&&
.AVIATION...
VFR WITH WINDS STARTING OUT OF THE NORTHWEST BUT BECOMING LIGHT AND
VARIABLE BY EVENING WITH HIGH PRESSURE OVERHEAD.
&&
.MARINE...
TODAY-TONIGHT...WINDS AND SEAS WILL DIMINISH THIS AFTERNOON WITH
HIGH PRESSURE MOVING INTO THE AREA. ALTHOUGH THE DAY BEGINS WITH A
SMALL CRAFT ADVISORY IN EFFECT FOR THE OFFSHORE ZONES...WINDS WILL
BE NEAR CALM WITH WAVE HEIGHTS OF ONLY 2-4 FEET BY TONIGHT.
TUE-TUE NIGHT...LIGHT TO GENTLE SRLY BREEZE TUE MORNING WILL FRESHEN
OUT OF THE SW AS A HIGH PRES RIDGE PUSHES ACRS FL AND INTO THE W
ATLC. WINDS BCMG W 15-20KTS NEARSHORE...20-25KTS OFFSHORE IN THE
PREDAWN HRS. OFFSHORE COMPONENT WILL LIMIT SEA HEIGHTS TO 2-3FT
NEARSHORE...OFFSHORE SEAS BUILDING FROM 2-3FT IN THE MORNING TO
4-6FT OVERNIGHT.
WED/WED NIGHT...HAZARDOUS BOATING CONDITIONS ANTICIPATED AS
SFC/BNDRY LYR WINDS SHIFT TO A FRESH NW BREEZE BEHIND A FAST MOVING
COLD FRONT. SEAS BUILDING TO 4-5FT NEARSHORE...6-8FT OFFSHORE
THU-FRI...WINDS WILL GRADUALLY DIMINISH AND VEER TO THE N THRU THE
END OF THE WEEK AS A LARGE POST FRONTAL HIGH PRES RIDGE BUILDS ACRS
THE SE CONUS. OVERALL BOATING CONDITIONS EXPECTED TO REMAIN MARGINAL
AT BEST...HOWEVER...AS A MODERATE TO FRESH NRLY BREEZE WILL GENERATE
ROUGH CONDITIONS ACRS THE LCL ATLC...ESPECIALLY IN THE GULF STREAM.
SEAS 3-4FT NEARSHORE AND 4-6FT OFFSHORE.
&&
TODAY-TONIGHT...ANOTHER DRY DAY IS IN STORE BUT AN ONSHORE WIND
COMPONENT AT THE COAST THIS AFTERNOON WILL MEAN THAT CRITICAL RH
VALUES WILL BE LIMITED TO INLAND AREAS. IN ADDITION...WINDS WILL BE
LIGHTER TODAY AT ONLY AROUND 5 MPH COINCIDING WITH THE LOWEST RH
VALUES.
TUE-WED...UPDATE TO FOLLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 62 42 73 55 / 0 0 0 30
MCO 66 43 76 58 / 0 0 0 20
MLB 63 42 75 59 / 0 0 0 20
VRB 63 40 76 58 / 0 0 0 20
LEE 65 44 75 56 / 0 0 0 30
SFB 65 43 75 57 / 0 0 0 20
ORL 65 46 75 58 / 0 0 0 20
FPR 64 42 75 59 / 0 0 0 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WARNING UNTIL 8 AM EST THIS MORNING FOR COASTAL VOLUSIA-
INLAND VOLUSIA-NORTHERN LAKE-SOUTHERN LAKE.
AM...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR WATERS
FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60
NM OFFSHORE-WATERS FROM SEBASTIAN INLET TO JUPITER INLET 20
TO 60 NM OFFSHORE-WATERS FROM VOLUSIA BREVARD COUNTY LINE
TO SEBASTIAN INLET 20 TO 60 NM OFFSHORE.
&&
$$
SHORT TERM/AVIATION...BOWEN
LONG TERM/IMPACT WX...BRAGAW
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1210 AM EST MON MAR 4 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD FROM THE WEST TONIGHT AND WILL PREVAIL
THROUGH EARLY THIS WEEK. LOW PRESSURE AND ITS TRAILING COLD FRONT
WILL IMPACT THE AREA TUESDAY NIGHT INTO EARLY WEDNESDAY...FOLLOWED
AGAIN BY HIGH PRESSURE THROUGH LATE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
NO MAJOR CHANGES WERE MADE FOR THE EARLY MORNING UPDATE. WATCHING
CIRRUS MOVING IN FROM THE NORTHWEST. RAP 600MB RH PROGS SUGGEST
MOST OF THIS WILL REMAIN TO THE NORTHWEST THROUGH DAYBREAK.
UNDER CLEAR SKIES...TEMPERATURES BY DAYBREAK WILL FALL INTO THE
MID TO UPPER 20S AT MOST LOCATIONS AWAY FROM THE IMMEDIATE COAST.
A FEW OF THE COLDEST LOCATIONS WELL INLAND COULD BRIEFLY BOTTOM
OUT IN THE LOWER 20S...AND TEMPERATURES CLOSE TO FREEZING WILL
EVEN OCCUR ON THE SEA ISLANDS/BEACHES. THESE LOW TEMPERATURES
WILL AVERAGE AS MUCH AS 15-20F BELOW AVERAGE FOR MARCH 4. AT
KSAV...THE MARCH 4 RECORD LOW OF 26 DEGREES LAST SET IN 2009 COULD
BE TIED OR EVEN ECLIPSED.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
MONDAY...THE ABNORMALLY DEEP TROUGH THAT IMPACTED THE AREA OVER THE
WEEKEND WILL FINALLY LIFT OUT...AND BECOMES REPLACED BY A BUILDING
RIDGE FROM THE WEST AND ITS ASSOCIATED RISING HEIGHTS. THE CYCLONIC
FLOW OF RECENT DAYS THAT EXTENDS FAR TO THE SW FROM DEEP LOW
PRESSURE NEAR THE COAST OF MAINE WILL GIVE WAY TO ANTICYCLONIC
CURVATURE OF THE ISOBARS AS HIGH PRESSURE ARRIVES FROM THE WEST.
ALTHOUGH THERE IS AN INCREASE IN JET STREAM CIRRIFORM CLOUDS IN THE
LATE MORNING AND AFTERNOON...CROSS-SECTIONS AND SOUNDINGS INDICATE
THAT THEY WILL BE MORE TRANSLUCENT RATHER THAN OPAQUE. THUS WITH
DECENT INSOLATION...A 20-30 METER RISE IN LOW LEVEL THICKNESS VALUES
AND A SOLID 8-10C CLIMB IN 850 MB TEMPS AND COLD ADVECTION
WANING...WE LOOK TO REACH THE MID 50S NORTH TO AROUND 60 SOUTH.
MONDAY NIGHT...THE SURFACE RIDGE SLIDES INTO THE ATLANTIC...THE
SYNOPTIC FLOW BACKS AROUND TO THE WEST AND SW...AND THERE IS A
STEADY INCREASE IN HIGHER LEVEL CLOUDS. THESE CLOUDS WILL THICKEN
WITH TIME FROM WEST TO EAST IN ASSOCIATION WITH THE UPPER JET AND IN
ADVANCE OF A LOW PRESSURE SYSTEM THAT ORGANIZES AS IT MOVES NE FROM
THE ARKLATEX TO KENTUCKY. WE/LL EXPERIENCE SOME RADIATIONAL COOLING
IN THE EVENING...BUT TEMPS WILL HOLD STEADY OR EVEN RISE LATE.
BOTTOM LINE THOUGHT...WE WILL BE CONSIDERABLE WARMER THAN WE WILL BE
24 HOURS PRIOR.
TUESDAY...A STRONG CUT OFF LOW WILL SHIFT FROM THE NORTHERN PLAINS
TO ILLINOIS...WITH ITS ASSOCIATED SURFACE LOW TO TREK EASTWARD
THROUGH THE OHIO VALLEY TOWARD THE CENTRAL APPALACHIANS. THE FORECAST
ZONES WILL LIE IN THE WARM SECTOR REGIME...WITH A WARM FRONT FOUND
IN NC AND A TRAILING COLD FRONT ORIENTED FROM NE TO SW TO CROSS THE
SOUTHERN PORTION OF THE MOUNTAINS BY 00Z WEDNESDAY. WITH ONLY MINIMAL
HEIGHT FALLS LATE AND THE BEST CONVERGENCE AND DEEPER MOISTURE TO
REMAIN OFF TO OUR WEST AND NW...THE CHANCES FOR ANY RAIN BEFORE
NIGHTFALL ARE SMALL. THERE IS A MOISTENING OF THE COLUMN...BUT THE
LOW LEVELS REMAIN QUITE DRY WITH DEW POINT DEPRESSIONS AS MUCH AS
20-25 DEGREES IF NOT MORE. THUS WE/LL CARRY ONLY 20 POPS IN THE
AFTERNOON NW OF A LINE FROM ABOUT JAMESTOWN TO SUMMERVILLE AND
YEMASSEE IN SC...AND NW OF A LIN FROM ABOUT SHAWNEE TO CLAXTON AND
REIDSVILLE IN GA. LATER FORECASTS MAY NEED TO ADJUST THESE POPS UP
OR DOWN...DEPENDING UPON TIMING OF THE APPROACHING FRONT. DESPITE AN
INCREASE IN CLOUD COVER...STRONG WARM ADVECTION WILL BOOST TEMPS TO
THEIR HIGHEST LEVELS IN ABOUT A WEEK. AWAY FROM THE MUCH COOLER
SHORELINE COMMUNITIES...UPPER 60S AND LOWER 70S WILL BE COMMON JUST
ABOUT EVERYWHERE. A 30-40 KT LOW LEVEL JET WILL SHIFT THROUGH THE
REGION...AND THAT ALONG WITH A TIGHTENING OF THE GRADIENT WILL ALLOW
FOR BREEZY TO WINDY CONDITIONS TO DEVELOP.
TUESDAY NIGHT...THE CUTOFF ALOFT MOVES THROUGH VIRGINIA AND
NC...WHICH TRIGGERS A TRIPLE POINT SURFACE LOW FORMING JUST TO THE
EAST OF THE FEATURE ALOFT. BETTER HEIGHTS FALLS LOCALLY WILL
ACCOMPANY THE LOW...AND THIS WILL WILL DRIVE THE COLD FRONT FAIRLY
QUICKLY THROUGH THE AREA FROM NW TO SE THROUGH THE NIGHT. POPS WILL
EASILY REACH THE 60-70 PERCENTILE...BUT EVEN THESE MAY BE
CONSERVATIVE AS REFINEMENTS WILL LIKELY BE REQUIRED ONCE THE EXACT
TIMING DETAILS ARE HASHED OUT. THERE IS LITTLE IF ANY SURFACE BASED
INSTABILITY...BUT SOME ELEVATED CAPE /200-300 J/KG/...SHOWALTERS
LESS THAN ZERO AND 0-6 KM BULK SHEAR OF 50 KT OR MORE. THEREFORE WE
CAN/T RULE OUT A LITTLE ELEVATED CONVECTION. THE QUICK PROGRESSION
OF THE FRONT SHOULD LIMIT OUR QPF VALUES...MAINLY IN THE RANGE FROM
0.10 TO 0.30 INCHES. WINDS WILL FLUCTUATE THROUGH THE NIGHT...BUT
ONCE THE FRONT MOVES THROUGH AND PRESSURES STEADILY RISE AND COLD
ADVECTION ENSUES...THEY WILL REMAIN ELEVATED AND PERIODICALLY BREEZY
OR EVEN WINDY. TEMPS WILL PLUNGE IN WAKE OF THE FRONT AND NOT FAR FROM
TYPICAL MINIMAL LEVELS.
WEDNESDAY...THE CUT OFF WILL FINALLY TRAP ITS SURFACE LOW UNDERNEATH
NEAR THE MID-ATLANTIC COAST. WE/LL BE IN THE DRY SLOT BEHIND THE
COLD FRONT THAT PULLS FAR AWAY THROUGH THE ATLANTIC...AND THE
WRAP-AROUND MOISTURE ASSOCIATED WITH THE STACKED LOW. ALTHOUGH THERE
ARE HINTS THAT SOME SHOWERS COULD MAKE A RUN FOR OUR FAR NORTHERN
AND/OR NE SECTIONS LATE...WE CURRENTLY ANTICIPATE THAT THE DAY WILL
BE FREE OF ANY PRECIPITATION. TEMPS WILL CERTAINLY BE COLDER THAN ON
TUESDAY...BUT DOWNSLOPE FLOW AND A DECENT AMOUNT OF SUNSHINE WILL
NEGATE SOME OF THE COLDER AIR IMPACTING THE REGION. EVEN SO...WE/RE
LOOKING AT HIGHS AS MUCH AS 10-15 DEGREES COLDER THAN ON TUESDAY. A
TIGHT PRESSURE GRADIENT ND THE PRESENCE OF A 25-35 KT LOW LEVEL JET
WILL PRODUCE A WINDY DAY AREA WIDE. WE MIGHT EVEN FLIRT WITH A WIND
ADVISORY IN SOME LOCALES...WITH WINDS OF 20-30 MPH SUSTAINED AND 35
OR 40 MPH IN GUSTS.
LAKE WINDS...WINDS WILL APPROACH ADVISORY CRITERIA TUESDAY AFTERNOON
AS A 30-40 KT LOW LEVEL JET PASSES OVER THE REGION. HOWEVER...MIXING
WILL BE LIMITED WITHIN A WARM ADVECTION REGIME OVER THE COOLER LAKE
WATERS. A BETTER CHANCE FOR LAKE WIND ADVISORY THRESHOLDS TO BE MET
TUESDAY NIGHT THROUGH EARLY THURSDAY...AS A SIGNIFICANTLY TIGHTENED
PRESSURE GRADIENT AND BOUTS OF STRONG COLD ADVECTION ENHANCES THE
MIXING AND SUPPORTS 20 TO 25 KT AND GUSTY OVER LAKE MOULTRIE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS THE POTENT LOW SYSTEM RAPIDLY TRACKS INTO THE ATLANTIC THROUGH
THE LATE WEEK PERIOD...SURFACE HIGH PRESSURE AND UPPER LEVEL
RIDGING WILL FOLLOW IN ITS WAKE. EXPECT DRY CONDITIONS TO THUS
PREVAIL THURSDAY THROUGH THE WEEKEND. RISING HEIGHTS ALOFT WILL
SUPPORT A GRADUAL WARMING TREND THROUGH THE PERIOD...WITH
TEMPERATURES PEAKING IN THE LOW TO MID 60S THURSDAY AND
FRIDAY...THEN POSSIBLY THE LOW 70S SATURDAY AND SUNDAY. LOW
TEMPERATURES WILL ALSO MODERATE INTO THE UPPER 30S TO LOWER 40S BY
LATE PERIOD.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...THERE IS A LOW TO MODERATE CHANCE OF
REDUCED FLIGHT CONDITIONS AT TIMES TUESDAY NIGHT AS A COLD FRONT
MOVES THROUGH THE AREA...ACCOMPANIED BY NUMEROUS SHRA. WINDY
CONDITIONS WILL ALSO IMPACT THE TERMINALS TUESDAY AFTERNOON
THROUGH THURSDAY.
&&
.MARINE...
MAINTAINED THE ONGOING SCA FOR AMZ354 AND 374 VALID UNTIL 10 AM
MONDAY.
SUNDAY EVENING...THE PRESSURE GRADIENT HAD RELAXED ACROSS SC
WATERS IN RESPONSE TO AN INLAND SURFACE TROUGH N/W OF THE WATERS.
AS A RESULT...WINDS HAD BACKED TOWARD THE SW AND HAD WEAKENED TO
15 KT OR LESS. HOWEVER...00Z GUIDANCE CONTINUES TO ADVERTISE
LOW LEVEL WINDS VEERING TOWARD THE NW AND SURGING TO AS MUCH AS 20
KT ACROSS SC WATERS OVERNIGHT. ACROSS GA NEARSHORE AND OUTER WATERS...
A TIGHTER SURFACE PRESSURE GRADIENT WILL MAINTAIN WINDS IN THE
20-25 KT RANGE...PERHAPS GUSTING NEAR 30 KT 40-60 NM
OFFSHORE...WITH THE WIND DIRECTION VEERING FROM W TO NW OVERNIGHT.
DUE TO THE OFFSHORE FETCH...SEAS SHOULD REMAIN 2-3 FT WITHIN 20 NM
AND 4 TO 6 FT BEYOND 20 NM OVERNIGHT.
MONDAY...AS COLD ADVECTION SHUTS OFF AND THE PRESSURE PATTERN
FINALLY RELAXES AS HIGH PRESSURE BUILDS FROM THE WEST...WINDS AND
SEAS WILL DECREASE THROUGH THE DAY. ONGOING SCA/S WILL END BY 15Z
AND IMPROVING CONDITIONS WILL DEVELOP FOR THE BALANCE OF THE DAY.
MONDAY NIGHT...HIGH PRESSURE WILL SITUATE ITSELF ATOP THE
WATERS...RESULTING IN QUIET MARINE CONDITIONS.
TUESDAY...HIGH PRESSURE ACROSS THE MARINE AREA EARLY WILL GIVE WAY
TO AN AREA OF LOW PRESSURE AND ITS COLD FRONT THAT MOVES THROUGH THE
SE QUADRANT OF THE NATION. THE PRESSURE GRADIENT WILL ONCE AGAIN
BECOME ENHANCED AS THIS PATTERN TRANSPIRES. ALTHOUGH THE WARM
ADVECTION WILL LIMIT MIXING...OUR WINDS AND SEAS WILL NONETHELESS BE
ON A STEADY RISE. AND WE COULD BE LOOKING AT MARGINAL SMALL CRAFT
ADVISORY CONDITIONS YET AGAIN.
TUESDAY NIGHT THROUGH WEDNESDAY...STRONG LOW PRESSURE WILL MOVE EAST
THROUGH THE MID ATLANTIC STATES...WITH ITS ASSOCIATED COLD FRONT TO
SWEEP THROUGH THE COASTAL WATERS THE LATTER PART OF TUESDAY NIGHT.
LARGE ISALLOBARIC PRESSURE FALLS WILL BE FOLLOWED BY LARGE
ISALLOBARIC PRESSURE RISES. THAT ALONG WITH STRONG COLD ADVECTION
DEVELOPING IN WAKE OF THE COLD FRONT WILL LEAD TO A HIGH PROBABILITY
OF GALES OVER MOST IF NOT ALL WATERS. THESE CONDITIONS WILL THEN
PERSIST THROUGH WEDNESDAY...POSSIBLY EVEN INTO WEDNESDAY NIGHT WITH
ANOTHER SURGE OF COLD ADVECTION AND STEADY PRESSURE RISES AS THE
SURFACE LOW MOVES INTO THE WESTERN ATLANTIC. MARINERS ARE ADVISED
THAT A FEW T-STORMS COULD PRECEDE THE COLD FRONT TUESDAY
NIGHT...PERHAPS ACCOMPANIED BY WINDS IN EXCESS OF 35 KT.
THURSDAY AND FRIDAY...THE ATLANTIC LOW WILL EVENTUALLY MOVE AWAY AND
GIVE WAY TO HIGH PRESSURE. IT/LL TAKE AWHILE...BUT IMPROVING
CONDITIONS WILL ARRIVE DURING THIS TIME.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ354-
374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1157 AM CST MON MAR 4 2013
.DISCUSSION...
ISSUED 1058 AM CST MON MAR 4 2013
THOUGH THE MAJORITY OF THE PRECIP IS OVER FOR THIS MORNING...SOME
WEAK WAA AND A COUPLE OF WAVES ON WATER VAPOR SAT IMAGERY MAY
RESULT IN SOME RAIN/SNOW SHOWERS THROUGH THE REMAINDER OF THE DAY.
GOING FORECAST IS ON TRACK FOR TODAY...INCLUDING THE HOURLY
TEMPERATURE TREND. WILL UPDATE THE FORECAST TO ELIMINATE MORNING
WORDING...BUT NO MAJOR CHANGES ARE ANTICIPATED IN THE SHORT TERM.
CLOUDY CONDITIONS AND A WEAK SOUTHERLY COMPONENT TO THE WINDS
SHOULD KEEP THE TEMPS IN THE 30S...AND CREEPING INTO THE LOW TO
MID 40S IN THE SRN HALF OF THE STATE.
&&
.AVIATION...
ISSUED 1149 AM CST MON MAR 4 2013
NOT MUCH OF A SHIFT IN THE MODEL DATA FOR THE PRECIPITATION
BEGINNING IN THE OVERNIGHT TONIGHT AND THROUGH TOMORROW MORNING.
PRECIPITATION TYPE AT THE BEGINNING OF THE EVENT...AFTER MIDNIGHT
AND INTO TOMORROW MORNING WILL BE A BIT OF AN ISSUE...WITH SN AND
PL THE MOST LIKELY TYPES. IN NRN TERMINALS...MORE LIKELY TO BE
SNOW...AND BY SHORTLY AFTER DAWN...SHOULD SEE THE CHANGE OVER TO
ALL SNOW. KEEPING IN THE PREDOMINANT WEATHER...THOUGH THE MORNING
AND PROBABLY THROUGHOUT THE DAY...THOUGH THE INTENSITY OF THE
SNOWFALL WILL LIKELY RESULT IN A CHANGE IN THE VISIBILITY FROM
TIME TO TIME. ESSENTIALLY...VFR THROUGH THE AFTERNOON AND INTO THE
EVENING WITH SOUTHEASTERLY WINDS AND GUSTS THROUGH THE AFTERNOON
TO 25KTS. AFTER MIDNIGHT...CONDITIONS WILL DETERIORATE AND STAY DOWN
THROUGH TOMORROW...IFR THROUGH THE PRECIPITATION AT BEST.
HJS
&&
.PREV DISCUSSION...
ISSUED 315 AM CST MON MAR 4 2013
TIGHT THERMAL GRADIENT MOVING INTO FAR WESTERN ILLINOIS EARLY THIS
MORNING...WITH 850 MB TEMPERATURES RISING ABOUT 6 DEGREES CELSIUS
IN ABOUT A 60 MILE SPAN. ISENTROPIC LIFT ASSOCIATED WITH THIS
GRADIENT HAS PRODUCED SOME LIGHT FREEZING RAIN AND SNOW OVER
IOWA...WITH LIGHT SNOW AND SLEET ACROSS WESTERN ILLINOIS JUST EAST
OF THE MISSISSIPPI RIVER. UPPER LOW DROPPING SOUTHEAST ACROSS
MONTANA IS PART OF THE MAIN SHOW THAT WILL BE AFFECTING OUR
WEATHER THE NEXT COUPLE DAYS...ALONG WITH A SURFACE LOW CURRENTLY
ANALYZED OVER WESTERN OKLAHOMA.
PRIMARY FORECAST CONCERN IN THE SHORT TERM INVOLVES PRECIPITATION
TYPES AND AMOUNTS THROUGH TUESDAY NIGHT. IN THE LONGER TERM...
FOCUS SHIFTS TOWARD A WARMER STORM SYSTEM THAT ARRIVES SOMETIME
NEXT WEEKEND.
SHORT TERM...TODAY THROUGH WEDNESDAY...
STRONGEST LIFT WITH THE CURRENT PRECIPITATION SHOULD LAST THROUGH
ABOUT MID MORNING...AND MOST OF THE MODELS HAVE BEEN WEAKENING
THIS PRECIPITATION WITH TIME. HIGHEST POPS EXPECTED TO BE EARLY
MORNING IN THE NORTHWEST CWA...WITH THE NAM...ECMWF AND RAP MODELS
ALL SUGGESTING MAINLY DRY CONDITIONS THE REMAINDER OF THE DAY.
SURFACE LOW PROGGED TO MOVE INTO WESTERN KENTUCKY AFTER
MIDNIGHT...WITH THE UPPER LOW DROPPING SOUTHEAST INTO CENTRAL
ILLINOIS BY LATE TUESDAY AFTERNOON. PRECIP DEVELOPMENT SHOULD
BEGIN IN EARNEST BY MID TO LATE THIS EVENING AND EXPAND
OVERNIGHT...AS INVERTED SURFACE TROUGH ASSOCIATED WITH THE LOW TO
OUR SOUTH SWINGS THROUGH THE AREA. HAVE SOME CONCERNS WITH PRECIP
TYPES OVERNIGHT AND EARLY TUESDAY...AS NAM AND GFS SOUNDINGS
SHOWING SOME DECENT WARMING IN THE LOWER LAYERS AFTER MIDNIGHT AND
SOME OF THE PRECIP MAY BE RAIN FOR A TIME AS FAR NORTH AS PEORIA.
WITH THE TREND TOWARD SOME WARMER CONDITIONS FOR A TIME... HAVE
HELD OFF ON ANY WINTER HEADLINES AS THE AMOUNT OF SNOW REMAINS IN
FLUX...BUT STILL LOOKS LIKE THE AREAS NORTH OF I-74 ARE MOST LIKELY
TO GET A FEW INCHES OR MORE OF ACCUMULATION THROUGH TUESDAY NIGHT.
MORE OF A TREND TOWARD SNOW IS EXPECTED ON TUESDAY AS THE SURFACE
LOW MOVES UP THE OHIO VALLEY. THE SOUTHEAST CWA IS EXPECTED TO
REMAIN RAIN A GOOD PORTION OF THE TIME...WITH A CHANGEOVER TO SNOW
LATE TUESDAY AFTERNOON. SNOW IS EXPECTED TO LINGER MOST OF THE
EVENING OVER THE ENTIRE AREA AS THE UPPER LOW PASSES...THEN
DIMINISH AFTER MIDNIGHT WITH THE LOW EXITING THE AREA.
LONG TERM...THURSDAY THROUGH SUNDAY...
A MUCH WARMER PATTERN IS STILL ON TAP FOR LATE WEEK...AS AN UPPER
LOW DIGS ALONG THE CALIFORNIA COAST AND PROVIDES A SOUTHWEST FLOW
INTO THE MIDWEST. MAIN FOCUS WILL BE WITH THE EVOLUTION OF THIS
LOW DURING THE WEEKEND...AND HOW THE BRANCHES OF THE JET STREAM
PHASE OVER THE CENTER OF THE COUNTRY. THE GFS MODEL CUTS THE LOW
OFF OVER THE DESERT SOUTHWEST AND PROVIDES MUCH MORE PHASING...
AND THUS A WETTER PATTERN LATER IN THE WEEKEND. MEANWHILE... THE
ECMWF IS MUCH SLOWER WITH LIFTING THE LOW NORTHEAST AND FORMING A
LARGE OCCLUDED SYSTEM OVER THE MID SECTION OF THE NATION...WHICH
WOULD HOLD OFF MUCH OF THE RAIN THREAT UNTIL LATER ON SUNDAY. WILL
GO WITH LOW POPS OF 20-30 PERCENT DURING THE WEEKEND FOR NOW...
HIGHEST IN THE WEST...BUT CONFIDENCE IS LOW DUE TO THE LARGE MODEL
DISCREPANCIES.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1117 AM CST MON MAR 4 2013
.DISCUSSION...
ISSUED 1058 AM CST MON MAR 4 2013
THOUGH THE MAJORITY OF THE PRECIP IS OVER FOR THIS MORNING...SOME
WEAK WAA AND A COUPLE OF WAVES ON WATER VAPOR SAT IMAGERY MAY
RESULT IN SOME RAIN/SNOW SHOWERS THROUGH THE REMAINDER OF THE DAY.
GOING FORECAST IS ON TRACK FOR TODAY...INCLUDING THE HOURLY
TEMPERATURE TREND. WILL UPDATE THE FORECAST TO ELIMINATE MORNING
WORDING...BUT NO MAJOR CHANGES ARE ANTICIPATED IN THE SHORT TERM.
CLOUDY CONDITIONS AND A WEAK SOUTHERLY COMPONENT TO THE WINDS
SHOULD KEEP THE TEMPS IN THE 30S...AND CREEPING INTO THE LOW TO
MID 40S IN THE SRN HALF OF THE STATE.
HJS
&&
.AVIATION...
ISSUED 551 AM CST MON MAR 4 2013
A WINTER STORM WILL APPROACH THE CENTRAL ILLINOIS TERMINALS DURING
THE 12Z TAF VALID TIME. A BAND OF MAINLY LIGHT SNOW WILL CROSS THE
AREA THIS MORNING...CAUSING A BRIEF REDUCTION TO MVFR OR IFR
CONDITIONS. WHILE ADDITIONAL PRECIPITATION IS POSSIBLE DURING THE
PERIOD...THE COVERAGE SHOULD BE QUITE LOW UNTIL VERY LATE TONIGHT.
THEN...A STEADIER SNOW WILL BEGIN TO SPREAD FROM WEST TO EAST
TOWARD DAYBREAK TUESDAY. THE MORE WIDESPREAD SNOW SHOULD BE
ACCOMPANIED BY IFR CONDITIONS.
PREDOMINANTLY SOUTHEAST WINDS ARE EXPECTED THROUGH THE PERIOD
AHEAD OF THE APPROACHING STORM. THE WINDS WILL GUST OVER 20 KTS AT
TIMES DURING THE DAYLIGHT HOURS TODAY.
BAK
&&
.PREV DISCUSSION...
ISSUED 315 AM CST MON MAR 4 2013
TIGHT THERMAL GRADIENT MOVING INTO FAR WESTERN ILLINOIS EARLY THIS
MORNING...WITH 850 MB TEMPERATURES RISING ABOUT 6 DEGREES CELSIUS
IN ABOUT A 60 MILE SPAN. ISENTROPIC LIFT ASSOCIATED WITH THIS
GRADIENT HAS PRODUCED SOME LIGHT FREEZING RAIN AND SNOW OVER
IOWA...WITH LIGHT SNOW AND SLEET ACROSS WESTERN ILLINOIS JUST EAST
OF THE MISSISSIPPI RIVER. UPPER LOW DROPPING SOUTHEAST ACROSS
MONTANA IS PART OF THE MAIN SHOW THAT WILL BE AFFECTING OUR
WEATHER THE NEXT COUPLE DAYS...ALONG WITH A SURFACE LOW CURRENTLY
ANALYZED OVER WESTERN OKLAHOMA.
PRIMARY FORECAST CONCERN IN THE SHORT TERM INVOLVES PRECIPITATION
TYPES AND AMOUNTS THROUGH TUESDAY NIGHT. IN THE LONGER TERM...
FOCUS SHIFTS TOWARD A WARMER STORM SYSTEM THAT ARRIVES SOMETIME
NEXT WEEKEND.
SHORT TERM...TODAY THROUGH WEDNESDAY...
STRONGEST LIFT WITH THE CURRENT PRECIPITATION SHOULD LAST THROUGH
ABOUT MID MORNING...AND MOST OF THE MODELS HAVE BEEN WEAKENING
THIS PRECIPITATION WITH TIME. HIGHEST POPS EXPECTED TO BE EARLY
MORNING IN THE NORTHWEST CWA...WITH THE NAM...ECMWF AND RAP MODELS
ALL SUGGESTING MAINLY DRY CONDITIONS THE REMAINDER OF THE DAY.
SURFACE LOW PROGGED TO MOVE INTO WESTERN KENTUCKY AFTER
MIDNIGHT...WITH THE UPPER LOW DROPPING SOUTHEAST INTO CENTRAL
ILLINOIS BY LATE TUESDAY AFTERNOON. PRECIP DEVELOPMENT SHOULD
BEGIN IN EARNEST BY MID TO LATE THIS EVENING AND EXPAND
OVERNIGHT...AS INVERTED SURFACE TROUGH ASSOCIATED WITH THE LOW TO
OUR SOUTH SWINGS THROUGH THE AREA. HAVE SOME CONCERNS WITH PRECIP
TYPES OVERNIGHT AND EARLY TUESDAY...AS NAM AND GFS SOUNDINGS
SHOWING SOME DECENT WARMING IN THE LOWER LAYERS AFTER MIDNIGHT AND
SOME OF THE PRECIP MAY BE RAIN FOR A TIME AS FAR NORTH AS PEORIA.
WITH THE TREND TOWARD SOME WARMER CONDITIONS FOR A TIME... HAVE
HELD OFF ON ANY WINTER HEADLINES AS THE AMOUNT OF SNOW REMAINS IN
FLUX...BUT STILL LOOKS LIKE THE AREAS NORTH OF I-74 ARE MOST LIKELY
TO GET A FEW INCHES OR MORE OF ACCUMULATION THROUGH TUESDAY NIGHT.
MORE OF A TREND TOWARD SNOW IS EXPECTED ON TUESDAY AS THE SURFACE
LOW MOVES UP THE OHIO VALLEY. THE SOUTHEAST CWA IS EXPECTED TO
REMAIN RAIN A GOOD PORTION OF THE TIME...WITH A CHANGEOVER TO SNOW
LATE TUESDAY AFTERNOON. SNOW IS EXPECTED TO LINGER MOST OF THE
EVENING OVER THE ENTIRE AREA AS THE UPPER LOW PASSES...THEN
DIMINISH AFTER MIDNIGHT WITH THE LOW EXITING THE AREA.
LONG TERM...THURSDAY THROUGH SUNDAY...
A MUCH WARMER PATTERN IS STILL ON TAP FOR LATE WEEK...AS AN UPPER
LOW DIGS ALONG THE CALIFORNIA COAST AND PROVIDES A SOUTHWEST FLOW
INTO THE MIDWEST. MAIN FOCUS WILL BE WITH THE EVOLUTION OF THIS
LOW DURING THE WEEKEND...AND HOW THE BRANCHES OF THE JET STREAM
PHASE OVER THE CENTER OF THE COUNTRY. THE GFS MODEL CUTS THE LOW
OFF OVER THE DESERT SOUTHWEST AND PROVIDES MUCH MORE PHASING...
AND THUS A WETTER PATTERN LATER IN THE WEEKEND. MEANWHILE... THE
ECMWF IS MUCH SLOWER WITH LIFTING THE LOW NORTHEAST AND FORMING A
LARGE OCCLUDED SYSTEM OVER THE MID SECTION OF THE NATION...WHICH
WOULD HOLD OFF MUCH OF THE RAIN THREAT UNTIL LATER ON SUNDAY. WILL
GO WITH LOW POPS OF 20-30 PERCENT DURING THE WEEKEND FOR NOW...
HIGHEST IN THE WEST...BUT CONFIDENCE IS LOW DUE TO THE LARGE MODEL
DISCREPANCIES.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
551 AM CST MON MAR 4 2013
.DISCUSSION...
ISSUED 315 AM CST MON MAR 4 2013
TIGHT THERMAL GRADIENT MOVING INTO FAR WESTERN ILLINOIS EARLY THIS
MORNING...WITH 850 MB TEMPERATURES RISING ABOUT 6 DEGREES CELSIUS
IN ABOUT A 60 MILE SPAN. ISENTROPIC LIFT ASSOCIATED WITH THIS
GRADIENT HAS PRODUCED SOME LIGHT FREEZING RAIN AND SNOW OVER
IOWA...WITH LIGHT SNOW AND SLEET ACROSS WESTERN ILLINOIS JUST EAST
OF THE MISSISSIPPI RIVER. UPPER LOW DROPPING SOUTHEAST ACROSS
MONTANA IS PART OF THE MAIN SHOW THAT WILL BE AFFECTING OUR
WEATHER THE NEXT COUPLE DAYS...ALONG WITH A SURFACE LOW CURRENTLY
ANALYZED OVER WESTERN OKLAHOMA.
PRIMARY FORECAST CONCERN IN THE SHORT TERM INVOLVES PRECIPITATION
TYPES AND AMOUNTS THROUGH TUESDAY NIGHT. IN THE LONGER TERM...
FOCUS SHIFTS TOWARD A WARMER STORM SYSTEM THAT ARRIVES SOMETIME
NEXT WEEKEND.
SHORT TERM...TODAY THROUGH WEDNESDAY...
STRONGEST LIFT WITH THE CURRENT PRECIPITATION SHOULD LAST THROUGH
ABOUT MID MORNING...AND MOST OF THE MODELS HAVE BEEN WEAKENING
THIS PRECIPITATION WITH TIME. HIGHEST POPS EXPECTED TO BE EARLY
MORNING IN THE NORTHWEST CWA...WITH THE NAM...ECMWF AND RAP MODELS
ALL SUGGESTING MAINLY DRY CONDITIONS THE REMAINDER OF THE DAY.
SURFACE LOW PROGGED TO MOVE INTO WESTERN KENTUCKY AFTER
MIDNIGHT...WITH THE UPPER LOW DROPPING SOUTHEAST INTO CENTRAL
ILLINOIS BY LATE TUESDAY AFTERNOON. PRECIP DEVELOPMENT SHOULD
BEGIN IN EARNEST BY MID TO LATE THIS EVENING AND EXPAND
OVERNIGHT...AS INVERTED SURFACE TROUGH ASSOCIATED WITH THE LOW TO
OUR SOUTH SWINGS THROUGH THE AREA. HAVE SOME CONCERNS WITH PRECIP
TYPES OVERNIGHT AND EARLY TUESDAY...AS NAM AND GFS SOUNDINGS
SHOWING SOME DECENT WARMING IN THE LOWER LAYERS AFTER MIDNIGHT AND
SOME OF THE PRECIP MAY BE RAIN FOR A TIME AS FAR NORTH AS PEORIA.
WITH THE TREND TOWARD SOME WARMER CONDITIONS FOR A TIME... HAVE
HELD OFF ON ANY WINTER HEADLINES AS THE AMOUNT OF SNOW REMAINS IN
FLUX...BUT STILL LOOKS LIKE THE AREAS NORTH OF I-74 ARE MOST LIKELY
TO GET A FEW INCHES OR MORE OF ACCUMULATION THROUGH TUESDAY NIGHT.
MORE OF A TREND TOWARD SNOW IS EXPECTED ON TUESDAY AS THE SURFACE
LOW MOVES UP THE OHIO VALLEY. THE SOUTHEAST CWA IS EXPECTED TO
REMAIN RAIN A GOOD PORTION OF THE TIME...WITH A CHANGEOVER TO SNOW
LATE TUESDAY AFTERNOON. SNOW IS EXPECTED TO LINGER MOST OF THE
EVENING OVER THE ENTIRE AREA AS THE UPPER LOW PASSES...THEN
DIMINISH AFTER MIDNIGHT WITH THE LOW EXITING THE AREA.
LONG TERM...THURSDAY THROUGH SUNDAY...
A MUCH WARMER PATTERN IS STILL ON TAP FOR LATE WEEK...AS AN UPPER
LOW DIGS ALONG THE CALIFORNIA COAST AND PROVIDES A SOUTHWEST FLOW
INTO THE MIDWEST. MAIN FOCUS WILL BE WITH THE EVOLUTION OF THIS
LOW DURING THE WEEKEND...AND HOW THE BRANCHES OF THE JET STREAM
PHASE OVER THE CENTER OF THE COUNTRY. THE GFS MODEL CUTS THE LOW
OFF OVER THE DESERT SOUTHWEST AND PROVIDES MUCH MORE PHASING...
AND THUS A WETTER PATTERN LATER IN THE WEEKEND. MEANWHILE... THE
ECMWF IS MUCH SLOWER WITH LIFTING THE LOW NORTHEAST AND FORMING A
LARGE OCCLUDED SYSTEM OVER THE MID SECTION OF THE NATION...WHICH
WOULD HOLD OFF MUCH OF THE RAIN THREAT UNTIL LATER ON SUNDAY. WILL
GO WITH LOW POPS OF 20-30 PERCENT DURING THE WEEKEND FOR NOW...
HIGHEST IN THE WEST...BUT CONFIDENCE IS LOW DUE TO THE LARGE MODEL
DISCREPANCIES.
GEELHART
&&
.AVIATION...
ISSUED 551 AM CST MON MAR 4 2013
A WINTER STORM WILL APPROACH THE CENTRAL ILLINOIS TERMINALS DURING
THE 12Z TAF VALID TIME. A BAND OF MAINLY LIGHT SNOW WILL CROSS THE
AREA THIS MORNING...CAUSING A BRIEF REDUCTION TO MVFR OR IFR
CONDITIONS. WHILE ADDITIONAL PRECIPITATION IS POSSIBLE DURING THE
PERIOD...THE COVERAGE SHOULD BE QUITE LOW UNTIL VERY LATE TONIGHT.
THEN...A STEADIER SNOW WILL BEGIN TO SPREAD FROM WEST TO EAST
TOWARD DAYBREAK TUESDAY. THE MORE WIDESPREAD SNOW SHOULD BE
ACCOMPANIED BY IFR CONDITIONS.
PREDOMINANTLY SOUTHEAST WINDS ARE EXPECTED THROUGH THE PERIOD
AHEAD OF THE APPROACHING STORM. THE WINDS WILL GUST OVER 20 KTS AT
TIMES DURING THE DAYLIGHT HOURS TODAY.
BAK
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
315 AM CST MON MAR 4 2013
.DISCUSSION...
ISSUED 315 AM CST MON MAR 4 2013
TIGHT THERMAL GRADIENT MOVING INTO FAR WESTERN ILLINOIS EARLY THIS
MORNING...WITH 850 MB TEMPERATURES RISING ABOUT 6 DEGREES CELSIUS
IN ABOUT A 60 MILE SPAN. ISENTROPIC LIFT ASSOCIATED WITH THIS
GRADIENT HAS PRODUCED SOME LIGHT FREEZING RAIN AND SNOW OVER
IOWA...WITH LIGHT SNOW AND SLEET ACROSS WESTERN ILLINOIS JUST EAST
OF THE MISSISSIPPI RIVER. UPPER LOW DROPPING SOUTHEAST ACROSS
MONTANA IS PART OF THE MAIN SHOW THAT WILL BE AFFECTING OUR
WEATHER THE NEXT COUPLE DAYS...ALONG WITH A SURFACE LOW CURRENTLY
ANALYZED OVER WESTERN OKLAHOMA.
PRIMARY FORECAST CONCERN IN THE SHORT TERM INVOLVES PRECIPITATION
TYPES AND AMOUNTS THROUGH TUESDAY NIGHT. IN THE LONGER TERM...
FOCUS SHIFTS TOWARD A WARMER STORM SYSTEM THAT ARRIVES SOMETIME
NEXT WEEKEND.
SHORT TERM...TODAY THROUGH WEDNESDAY...
STRONGEST LIFT WITH THE CURRENT PRECIPITATION SHOULD LAST THROUGH
ABOUT MID MORNING...AND MOST OF THE MODELS HAVE BEEN WEAKENING
THIS PRECIPITATION WITH TIME. HIGHEST POPS EXPECTED TO BE EARLY
MORNING IN THE NORTHWEST CWA...WITH THE NAM...ECMWF AND RAP MODELS
ALL SUGGESTING MAINLY DRY CONDITIONS THE REMAINDER OF THE DAY.
SURFACE LOW PROGGED TO MOVE INTO WESTERN KENTUCKY AFTER
MIDNIGHT...WITH THE UPPER LOW DROPPING SOUTHEAST INTO CENTRAL
ILLINOIS BY LATE TUESDAY AFTERNOON. PRECIP DEVELOPMENT SHOULD
BEGIN IN EARNEST BY MID TO LATE THIS EVENING AND EXPAND
OVERNIGHT...AS INVERTED SURFACE TROUGH ASSOCIATED WITH THE LOW TO
OUR SOUTH SWINGS THROUGH THE AREA. HAVE SOME CONCERNS WITH PRECIP
TYPES OVERNIGHT AND EARLY TUESDAY...AS NAM AND GFS SOUNDINGS
SHOWING SOME DECENT WARMING IN THE LOWER LAYERS AFTER MIDNIGHT AND
SOME OF THE PRECIP MAY BE RAIN FOR A TIME AS FAR NORTH AS PEORIA.
WITH THE TREND TOWARD SOME WARMER CONDITIONS FOR A TIME... HAVE
HELD OFF ON ANY WINTER HEADLINES AS THE AMOUNT OF SNOW REMAINS IN
FLUX...BUT STILL LOOKS LIKE THE AREAS NORTH OF I-74 ARE MOST LIKELY
TO GET A FEW INCHES OR MORE OF ACCUMULATION THROUGH TUESDAY NIGHT.
MORE OF A TREND TOWARD SNOW IS EXPECTED ON TUESDAY AS THE SURFACE
LOW MOVES UP THE OHIO VALLEY. THE SOUTHEAST CWA IS EXPECTED TO
REMAIN RAIN A GOOD PORTION OF THE TIME...WITH A CHANGEOVER TO SNOW
LATE TUESDAY AFTERNOON. SNOW IS EXPECTED TO LINGER MOST OF THE
EVENING OVER THE ENTIRE AREA AS THE UPPER LOW PASSES...THEN
DIMINISH AFTER MIDNIGHT WITH THE LOW EXITING THE AREA.
LONG TERM...THURSDAY THROUGH SUNDAY...
A MUCH WARMER PATTERN IS STILL ON TAP FOR LATE WEEK...AS AN UPPER
LOW DIGS ALONG THE CALIFORNIA COAST AND PROVIDES A SOUTHWEST FLOW
INTO THE MIDWEST. MAIN FOCUS WILL BE WITH THE EVOLUTION OF THIS
LOW DURING THE WEEKEND...AND HOW THE BRANCHES OF THE JET STREAM
PHASE OVER THE CENTER OF THE COUNTRY. THE GFS MODEL CUTS THE LOW
OFF OVER THE DESERT SOUTHWEST AND PROVIDES MUCH MORE PHASING...
AND THUS A WETTER PATTERN LATER IN THE WEEKEND. MEANWHILE... THE
ECMWF IS MUCH SLOWER WITH LIFTING THE LOW NORTHEAST AND FORMING A
LARGE OCCLUDED SYSTEM OVER THE MID SECTION OF THE NATION...WHICH
WOULD HOLD OFF MUCH OF THE RAIN THREAT UNTIL LATER ON SUNDAY. WILL
GO WITH LOW POPS OF 20-30 PERCENT DURING THE WEEKEND FOR NOW...
HIGHEST IN THE WEST...BUT CONFIDENCE IS LOW DUE TO THE LARGE MODEL
DISCREPANCIES.
GEELHART
&&
.AVIATION...
ISSUED 1151 PM CST SUN MAR 3 2013...FOR THE 06Z TAFS
MID LEVEL WARM AIR ADVECTION IS LIFTING THE BOUNDARY LAYER AIR MASS
AND PRODUCING LIGHT FREEZING RAIN IN MOST OF CENTRAL AND WESTERN IOWA
AND NORTH CENTRAL MISSOURI...WITH LIGHT SNOW REPORTED IN NORTH CENTRAL
IOWA. THAT BAND OF FORCING FOR PRECIP IS ENTERING WC IL AND WILL
EVENTUALLY NEAR SPI AFTER MIDNIGHT. WE EXPECT MAINLY VFR CLOUDS
TONIGHT. SOME IFR CLOUDS AND/OR VIS WILL BE POSSIBLE MONDAY
MORNING MAINLY FOR PIA AS SNOW DEVELOPS AND ACCUMULATES UP TO ONE
HALF INCH OR SO. OTHER TERMINALS WILL HAVE LOWER CHANCES FOR
MEASURABLE SNOW WITH BMI HAVING BETTER CHANCES THAN THE OTHERS.
CAN NOT RULE OUT A BRIEF PERIOD OF FREEZING RAIN OR SLEET FOR
SPI/PIA LATER TONIGHT AND MON MORNING...BUT ICING SHOULD BE
MINIMAL IF ANY DEVELOPS.
GENERALLY A BREAK IN THE PRECIP IS FORECAST FOR MONDAY AFTERNOON
THROUGH MIDNIGHT MON NIGHT...WITH ONLY MINOR LIGHT SNOW OR LIGHT
RAIN EXPECTED. WE LEFT MAINLY A VCSH TO COVER THE OTHER PERIODS
OUTSIDE OF MON MORNING.
WINDS WILL INCREASE FROM THE SOUTHEAST MON MORNING...WITH
SUSTAINED WINDS OF 14-17KT AND GUSTS TO 25KT. DECREASING WINDS
WILL DEVELOP TOWARD SUNSET.
ADDITIONAL SNOWS ARE EXPECTED TO ARRIVE JUST BEYOND THIS 24HR TAF
PERIOD. BY TUESDAY MORNING...SNOW INTENSITY SHOULD INCREASE
DRAMATICALLY FROM WEST TO EAST.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
325 PM CST MON MAR 4 2013
...UPDATED LONG TERM SECTION...
.SYNOPSIS...
ISSUED AT 254 PM CST MON MAR 4 2013
WATER VAPOR AND HOURLY RAP ANALYSES SHOW A FAIRLY COMPACT JET STREAK
MOVING SOUTHEAST FROM IDAHO INTO COLORADO. THIS JET STREAK WAS WELL
TO THE SOUTHWEST OF THE MAIN UPPER LOW CENTER WHICH WAS CENTERED
ALONG THE WESTERN SOUTH DAKOTA-NORTH DAKOTA BORDER. THE FIRST
FRONTAL PASSAGE OCCURRED EARLIER IN THE DAY, BUT THE AIRMASS BEHIND
THIS FRONT WAS MAINLY DOWNSLOPE MODIFIED CONTINENTAL POLAR AIR...AND
NOT ARCTIC IN NATURE AT ALL. BECAUSE OF THIS...INSOLATION AND
CONTINUED DOWNSLOPE MODIFICATION YIELDED AFTERNOON TEMPERATURES
QUITE MILD AND RIGHT AROUND THE SEASONAL AVERAGE FOR EARLY MARCH.
THE EXCEPTION OF THIS WAS ACROSS SOUTH CENTRAL KANSAS WHERE
LINGERING SNOWPACK CONTINUED GENERALLY FROM HAYS TO KINSLEY TO
COLDWATER AND POINTS EAST (ESPECIALLY PRATT AND BARBER COUNTIES).
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 254 PM CST MON MAR 4 2013
LOWER-MID LEVEL CLOUD WILL CONTINUE TO INCREASE LATE THIS AFTERNOON
AND EVENING AS UPWARD VERTICAL MOTION INCREASES AHEAD OF THE
APPROACHING JET STREAK. RADAR ECHOES CONTINUED TO INCREASE ACROSS
NORTHEASTERN COLORADO AND AS THE UPPER JET STREAK APPROACHES WESTERN
KANSAS...FRONTOGENESIS IN THE MID TROPOSPHERE WILL FURTHER
INCREASE...AND RAIN/SNOW SHOWERS WILL INCREASE IN COVERAGE. POPS
WERE INCREASED TO THE 30-40 PERCENT ACROSS FAR WEST CENTRAL
KANSAS...AND THE CHALLENGE OF PRECIPITATION TYPE IS PRETTY HIGH
GIVEN THE RAPID COOLING OF THE 900-800MB LAYER EARLY THIS EVENING AS
THE SECOND COLD FRONT MOVES THROUGH AND EVAPORATIVE COOLING ENSUES.
THE INCREASING RADAR TRENDS ACROSS NORTHWEST KANSAS WOULD SUGGEST AN
INCREASE IN POPS ACROSS THE BOARD...SO BY PRESS TIME BEFORE 21Z WILL
HAVE POPS INCREASED AND SLIGHTLY HIGHER QPF AMOUNTS. THE PERIOD FROM
ROUGHLY 00Z TO 06Z WILL BE THE BEST TIME FRAME FOR LIGHT
ACCUMULATING PRECIPITATION AS THE 700MB FRONTOGENETIC MOVES QUICKLY
SOUTHEAST ACROSS WESTERN KANSAS. WILL BEGIN A RAPID CLEARING TREND
IN THE GRIDS TOWARD DAYBREAK TUESDAY. WE WILL REMAIN IN A FAIRLY
STRONG 850-700MB GRADIENT THROUGH MOST OF THE DAY TUESDAY WHICH WILL
KEEP WINDS UP IN THE BREEZY TO WINDY CATEGORY...BUT REMAINING BELOW
WIND ADVISORY CRITERIA AS IT LOOKS RIGHT NOW. HIGH TEMPERATURE
FORECAST WILL NOT BE CHANGED FROM THE GOING FORECAST WITH WIDESPREAD
LOWER TO MID 40S EXPECTED.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 PM CST MON MAR 4 2013
GOOD POTENTIAL EXISTS FOR COLDER TEMPERATURES OVERNIGHT TUESDAY
INTO EARLY WEDNESDAY MORNING. THE CENTER OF THE HIGH PRESSURE
SURFACE RIDGE AXIS WILL LIKELY BE CENTERED ACROSS CENTRAL KANSAS FOR
SEVERAL HOURS TUESDAY NIGHT. THIS WILL ALSO BE UNDER A VERY DRY DEEP
ATMOSPHERIC COLUMN, PROMOTING LONGWAVE RADIATIONAL COOLING.
SURFACE WINDS WILL QUICKLY TURN SOUTHEASTERLY ON THE WEST SIDE OF
THE RIDGE EARLY WEDNESDAY MORNING, AND EVEN BEFORE THAT ACROSS FAR
WESTERN KANSAS. THE MESOSCALE NAM INDICATES A POCKET OF THE COLDEST
POSSIBLE TEMPERATURES OF ALL MODEL OUTPUT AND MOS GUIDANCE. HOWEVER
IT APPEARS TO BE HAVING PROBLEMS ACCOUNTING FOR LEFTOVER SURFACE
SNOWDEPTH. THE ECMWF MOS APPEARS A GENERALLY REASONABLE BETTER
COMPROMISE IN THIS INSTANCE, AND WAS CLOSELY FOLLOWED WEDNESDAY
MORNING.
WEDNESDAY AFTERNOON WILL BRING WARMER TEMPERATURES, ESPECIALLY ACROSS
WESTERN KANSAS. THE NAM MODEL INDICATES A SHARP 850 MB LEVEL
TEMPERATURE GRADIENT ACROSS FROM AROUND DODGE CITY TO THE COLORADO
LINE, WITH SOUTHERLY SURFACE WINDS AROUND A DEVELOPING LEE SURFACE
LOW. EVEN WARMER BOUNDARY LAYER AIR WILL BE PRESENT EARLY BY
THURSDAY AFTERNOON. BY THURSDAY THE AXIS OF THE MID LEVEL THERMAL
RIDGE BECOMES CENTERED OVER THE HIGH PLAINS, AND THE SURFACE TROUGH
PULLS SLIGHTLY FARTHER EASTWARD, DRAWING IN WARMER AIR FROM THE
HIGHER TERRAIN OF SE COLORADO AND NE NEW MEXICO. WARMER OVERNIGHT
LOWS WILL BE EXPERIENCED AS WELL AS PERSISTENT SOUTHERLY WINDS
DURING THE OVERNIGHTS IN SLIGHTLY HIGHER THETA-E AIR. MELTING SNOW
IS LIKELY TO RE-FREEZE IN MOST CASES, AND IT IS NOT OBVIOUS AT THIS
POINT OF ANY NIGHTS APPEARING OVERLY PRONE TO DENSE FOG DEVELOPMENT.
A BETTER CHANCE FOR DENSE FOG WILL COME CLOSER TO THE BEGINNING OF
THE DYNAMIC LOW EXPECTED THIS WEEKEND STARTING AROUND FRIDAY.
LARGE UNCERTAINTY EXISTS WITH RESPECT TO THE STORM SYSTEM EXPECTED TO
INTENSIFY ACROSS THE CENTRAL HIGH PLAINS REGION BETWEEN FRIDAY AND
SUNDAY. THE ECMWF AND CANADIAN (GEM) MODELS ARE IN GENERALLY CLOSER
AGREEMENT TO ONE ANOTHER WITH A MORE BAROCLINIC SYSTEM, AS WELL AS
CONSIDERABLY SLOWER THAN THE GFS MODEL (BY AROUND 12 HOURS). THE
RECENT MODEL CONSENSUS, BLENDED WITH THE LAST FORECAST DOES LOWER
PROBABILITIES ON FRIDAY AND FRIDAY NIGHT, AND FOCUSES THE HIGHER
(LIKELY) CHANCES SATURDAY INTO SUNDAY. TEMPERATURES WILL ALSO BE A
CHALLENGE DURING THIS PERIOD. THE TRACK AND NATURE OF THE DYNAMIC
LOW WILL MAKE A LARGE DIFFERENCE, WITH A HIGH TEMPERATURE ENSEMBLE
SPREAD SATURDAY FROM THE LOW 40S TO LOW 60S. BETTER MODEL AGREEMENT
WILL BE LOOKED FOR AS THE SYSTEM BECOMES BETTER SAMPLED LATER IN THE
WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1154 AM CST MON MAR 4 2013
AS A FAIRLY INTENSE STORM SYSTEM TRACKS SOUTHEAST ACROSS THE
NORTHERN PLAINS TODAY AND TONIGHT...WINDS WILL STAY FAIRLY STRONG
FROM THE NORTH THROUGH THIS AFTERNOON AND TONIGHT. A SECONDARY COLD
FRONTAL SURGE WILL CAUSE A SLIGHT SHIFT IN THE WIND FROM
NORTH-NORTHEAST TO NORTH OR NORTH-NORTHWEST AND A SLIGHT INCREASE TO
24-26 KNOTS (GUSTING TO 31 TO 34 KNOTS). SOME LIGHT RAIN OR SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE EARLY TO MID EVENING
HOURS...HOWEVER THE SHOWERS ARE EXPECTED TO BE LIGHT IN NATURE AND
LAST NO LONGER THAN AN HOUR OR TWO. THE IMPACTS AT THE TERMINALS
WILL BE MINIMAL AND WILL NOT EVEN INCLUDE THEM IN THE TAFS. CEILING
IS NOT EXPECTED TO FALL BELOW 3 OR 4 THOUSAND FEET EXCEPT AT
GCK...WHERE MVFR CEILINGS WILL BE FORECAST FROM MID TO LATE EVENING.
SKY CLEAR CONDITIONS WILL BE EXPECTED AFTER THE STORM PASSES TO THE
NORTHEAST TOMORROW.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 22 42 17 52 / 20 0 0 0
GCK 20 44 16 54 / 40 0 0 0
EHA 22 48 24 61 / 30 10 0 0
LBL 20 47 19 54 / 20 10 0 0
HYS 22 40 14 46 / 20 10 0 0
P28 25 43 16 49 / 20 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...RUSSELL
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
256 PM CST MON MAR 4 2013
...UPDATED SYNOPSIS AND SHORT TERM SECTIONS...
.SYNOPSIS...
ISSUED AT 254 PM CST MON MAR 4 2013
WATER VAPOR AND HOURLY RAP ANALYSES SHOW A FAIRLY COMPACT JET STREAK
MOVING SOUTHEAST FROM IDAHO INTO COLORADO. THIS JET STREAK WAS WELL
TO THE SOUTHWEST OF THE MAIN UPPER LOW CENTER WHICH WAS CENTERED
ALONG THE WESTERN SOUTH DAKOTA-NORTH DAKOTA BORDER. THE FIRST
FRONTAL PASSAGE OCCURRED EARLIER IN THE DAY, BUT THE AIRMASS BEHIND
THIS FRONT WAS MAINLY DOWNSLOPE MODIFIED CONTINENTAL POLAR AIR...AND
NOT ARCTIC IN NATURE AT ALL. BECAUSE OF THIS...INSOLATION AND
CONTINUED DOWNSLOPE MODIFICATION YIELDED AFTERNOON TEMPERATURES
QUITE MILD AND RIGHT AROUND THE SEASONAL AVERAGE FOR EARLY MARCH.
THE EXCEPTION OF THIS WAS ACROSS SOUTH CENTRAL KANSAS WHERE
LINGERING SNOWPACK CONTINUED GENERALLY FROM HAYS TO KINSLEY TO
COLDWATER AND POINTS EAST (ESPECIALLY PRATT AND BARBER COUNTIES).
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 254 PM CST MON MAR 4 2013
LOWER-MID LEVEL CLOUD WILL CONTINUE TO INCREASE LATE THIS AFTERNOON
AND EVENING AS UPWARD VERTICAL MOTION INCREASES AHEAD OF THE
APPROACHING JET STREAK. RADAR ECHOES CONTINUED TO INCREASE ACROSS
NORTHEASTERN COLORADO AND AS THE UPPER JET STREAK APPROACHES WESTERN
KANSAS...FRONTOGENESIS IN THE MID TROPOSPHERE WILL FURTHER
INCREASE...AND RAIN/SNOW SHOWERS WILL INCREASE IN COVERAGE. POPS
WERE INCREASED TO THE 30-40 PERCENT ACROSS FAR WEST CENTRAL
KANSAS...AND THE CHALLENGE OF PRECIPITATION TYPE IS PRETTY HIGH
GIVEN THE RAPID COOLING OF THE 900-800MB LAYER EARLY THIS EVENING AS
THE SECOND COLD FRONT MOVES THROUGH AND EVAPORATIVE COOLING ENSUES.
THE INCREASING RADAR TRENDS ACROSS NORTHWEST KANSAS WOULD SUGGEST AN
INCREASE IN POPS ACROSS THE BOARD...SO BY PRESS TIME BEFORE 21Z WILL
HAVE POPS INCREASED AND SLIGHTLY HIGHER QPF AMOUNTS. THE PERIOD FROM
ROUGHLY 00Z TO 06Z WILL BE THE BEST TIME FRAME FOR LIGHT
ACCUMULATING PRECIPITATION AS THE 700MB FRONTOGENETIC MOVES QUICKLY
SOUTHEAST ACROSS WESTERN KANSAS. WILL BEGIN A RAPID CLEARING TREND
IN THE GRIDS TOWARD DAYBREAK TUESDAY. WE WILL REMAIN IN A FAIRLY
STRONG 850-700MB GRADIENT THROUGH MOST OF THE DAY TUESDAY WHICH WILL
KEEP WINDS UP IN THE BREEZY TO WINDY CATEGORY...BUT REMAINING BELOW
WIND ADVISORY CRITERIA AS IT LOOKS RIGHT NOW. HIGH TEMPERATURE
FORECAST WILL NOT BE CHANGED FROM THE GOING FORECAST WITH WIDESPREAD
LOWER TO MID 40S EXPECTED.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 232 AM CST MON MAR 4 2013
STARTING WITH TUESDAY, A COLD FRONT WILL HAVE WENT THROUGH WESTERN
KANSAS LATE TODAY (MONDAY), AND COLD HIGH PRESSURE AT THE SURFACE
WILL WEDGE A NOSE OF COLDER AIR SOUTHWARD. IN THE UPPER ATMOSPHERE,
A LARGE TROUGH OF LOW PRESSURE WILL SWING FROM NORTHWEST TO EAST
THROUGH KANSAS. THIS WILL CERTAINLY BRING MID AND HIGH LEVEL
MOISTURE, AND A LITTLE MOISTURE MAY BE SQUEEZED OUT VERY EARLY
TUESDAY. HOWEVER, THE SUPPRESSION FROM THE UPPER HIGH PRESSURE WILL
LIKELY OVERPOWER ANY DEVELOPMENT OF LIGHT PRECIP, AND THUS
PRECIPITATION CHANCES WILL BE NIL TUE. MAXIMUM TEMPERATURES IN THE
HAYS AREAS DOWN TO THE GREENSBURG AREAS WILL BARELY REACH 40F ON
TUESDAY, WITH HIGHS IN THE UPPER 40S DOWN NEAR ELKHART AND JOHNSON
CITY. AN UPPER LEVEL RIDGE WILL BUILD IN FROM THE WEST WEDNESDAY
AND THURSDAY, BRINGING WARMER MAXIMUM TEMPERATURES IN BY THURSDAY.
MAXIMUM TEMPERATURES THURSDAY WILL RANGE FROM THE MID TO UPPER 50S
EAST OF HIGHWAY 183, TO AS HIGH AS THE LOWER 70S ALONG THE COLORADO
BORDER. THE UPPER FLOW WILL TURN SOUTHWEST FRIDAY, AS A LARGE UPPER
LEVEL LOW MOVES INTO SOUTHERN CALIFORNIA. PRECIPITATION WILL ALSO
BE HEADING TOWARD KANSAS ON SATURDAY, BUT I DO NOT THINK ANY
CONVECTION WILL MAKE IT INTO WESTERN KANSAS PRIOR TO SATURDAY NIGHT.
FROM SATURDAY NIGHT INTO SUNDAY NIGHT, THAT UPPER LOW WILL BE MOVING
FROM NORTHERN ARIZONA EAST-NORTHEAST THROUGH KANSAS. AS THE LOW
APPROACHES WESTERN KANSAS, DEEPER AND DEEPER MOISTURE WILL EVOLVE.
SHOWERS AND THUNDERSTORMS ARE LIKELY OVER MUCH OF THE WESTERN PLAINS
FROM SATURDAY NIGHT INTO SUNDAY NIGHT. THIS COULD BE THE FIRST
LIQUID CONVECTION OF THE YEAR. RIGHT NOW, IT IS TOO EARLY TO
DETERMINE IF ANY STORMS WILL BE SEVERE OR NOT. ALL MODELS EXCEPT
THE GFS MODEL ARE PAINTING FROM 0.20 TO 0.60 INCH OF PRECIP FOR
SOUTHWEST KANSAS. THIS WILL BE VERY WELCOMED MOISTURE FOR MOST OF
THE SOUTHWEST KANSANS, AS THE 2 1/2 YEAR OLD DROUGHT IS ONGOING. BY
SATURDAY NIGHT, SOME COLD AIR WILL MIX DOWN INTO THE LOWER LAYERS,
AND THE ECMWF 1000-850 THICKNESS FIELDS DROP TO BELOW 1320DM IN THE
WEST AND NORTHWEST SECTIONS OF OUR FORECAST AREA. SO, I PLACE A
PRECIP TYPE OF RAIN OR SNOW NORTH AND WEST OF A LINE FROM HAYS TO
JOHNSON CITY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1154 AM CST MON MAR 4 2013
AS A FAIRLY INTENSE STORM SYSTEM TRACKS SOUTHEAST ACROSS THE
NORTHERN PLAINS TODAY AND TONIGHT...WINDS WILL STAY FAIRLY STRONG
FROM THE NORTH THROUGH THIS AFTERNOON AND TONIGHT. A SECONDARY COLD
FRONTAL SURGE WILL CAUSE A SLIGHT SHIFT IN THE WIND FROM
NORTH-NORTHEAST TO NORTH OR NORTH-NORTHWEST AND A SLIGHT INCREASE TO
24-26 KNOTS (GUSTING TO 31 TO 34 KNOTS). SOME LIGHT RAIN OR SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE EARLY TO MID EVENING
HOURS...HOWEVER THE SHOWERS ARE EXPECTED TO BE LIGHT IN NATURE AND
LAST NO LONGER THAN AN HOUR OR TWO. THE IMPACTS AT THE TERMINALS
WILL BE MINIMAL AND WILL NOT EVEN INCLUDE THEM IN THE TAFS. CEILING
IS NOT EXPECTED TO FALL BELOW 3 OR 4 THOUSAND FEET EXCEPT AT
GCK...WHERE MVFR CEILINGS WILL BE FORECAST FROM MID TO LATE EVENING.
SKY CLEAR CONDITIONS WILL BE EXPECTED AFTER THE STORM PASSES TO THE
NORTHEAST TOMORROW.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 22 42 17 52 / 20 0 0 0
GCK 20 44 16 54 / 20 0 0 0
EHA 22 48 24 61 / 30 10 0 0
LBL 20 47 19 54 / 20 10 0 0
HYS 22 40 14 46 / 10 10 0 0
P28 25 43 16 49 / 20 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...BURKE
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
612 PM EST TUE MAR 5 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS SHORTWAVE
DROPPING SE INTO THE MID MISSISSIPPI VALLEY. WAVE IS BEING FORCED SE
BY MID LEVEL HIGH OVER QUEBEC. AS A RESULT...SYSTEM SNOW HAS PAST BY
TO THE W AND S OF UPPER MI TODAY. SOME VERY LIGHT LES IS OCCURRING
IN E TO NE FLOW ACROSS LAKE SUPERIOR INTO THE KEWEENAW AND NCNTRL
UPPER MI AS TEMPS AT THE BASE OF A LOW 3KFT INVERSION ARE JUST
SUFFICIENT FOR LES AT -11C. UNDER DOWNSLOPING E TO NE LOW-LEVEL
WINDS...THE ERN FCST AREA HAS ENJOYED A SUNNY DAY TODAY.
VIGOROUS SHORTWAVE/MID LEVEL LOW OVER THE MID MISSISSIPPI VALLEY
WILL MOVE TO VCNTY OF NC BY WED MORNING AND WILL HAVE LITTLE IMPACT
ON WEATHER HERE. WHAT WILL BE A FACTOR IS A NRN STREAM SHORTWAVE
THAT WILL BE DRIFTING INTO THE UPPER LAKES LATE TONIGHT/WED...
BRINGING A DECENT AREA OF DEEP LAYER FORCING PER QVECTORS. THE
APPROACHING SHORTWAVE WILL HELP SHARPEN LOW-LEVEL CYCLONIC N TO NE
FLOW ACROSS LAKE SUPERIOR TONIGHT/WED MORNING BEFORE WINDS SHIFT NW
WED AS THE WAVE REACHES THE AREA. WHILE LOW-LEVEL THERMAL PROFILE
CHANGES VERY LITTLE...OVERWATER INSTABILITY IS MORE THAN SUFFICIENT
FOR LAKE ENHANCEMENT...AND THE FACT THAT SOME VERY LIGHT LES IS
ALREADY OCCURRING SUGGESTS THERE SHOULD BE A DECENT UPTICK IN LES
TONIGHT/WED MORNING. WITH ALL MODEL GUIDANCE SHOWING A SSE TO NNW
ORIENTED SFC TROF DEVELOPING ACROSS ROUGHLY CNTRL LAKE SUPERIOR...IT
WOULD APPEAR THAT NW AND NCNTRL UPPER MI SHOULD BE FAVORED FOR MORE
PERSISTENT SNOW. SNOW TO WATER RATIOS SHOULD BE ON THE LOW SIDE
10-15 TO 1...EXCEPT IN THE VCNTY/ALONG THE AFORENTIONED SFC TROF
WHERE DEEPER VERTICAL MOTION...THOUGH NOT STRONG...SHOULD INTERSECT
THE DGZ AND POSSIBLY BOOST RATIOS TOWARD 20 TO 1. AT THIS POINT...IT
APPEARS ACCUMULATIONS UPWARDS OF AROUND 3 INCHES ARE POSSIBLE OVER
NW/NCNTRL HIGHER TERRAIN TONIGHT/WED MORNING. ACCUMULATIONS SHOULD
BE A LITTLE LESS FARTHER W TOWARD KIWD. IT REALLY WON`T BE UNTIL
LATER WED MORNING/AFTN WHEN SFC TROF PASSES THAT SNOW REACHES THE NE
FCST AREA. AWAY FROM LAKE ENHANCEMENT...EXPECT SOME -SN/-SHSN TIED
TO SHORT PERIOD OF STRONGER FORCING ASSOCIATED WITH SHORTWAVE. -SHSN
WILL DIMINISH W TO E WED AFTN AND MAY END OVER THE W.
TEMPS TONIGHT ARE FAIRLY STRAIGHTFORWARD WITH CLOUD COVER LIMITING
TEMP FALL. ONE EXCEPTION IS THE ERN FCST AREA AS IT`S UNCERTAIN WHEN
CLOUDS WILL INCREASE SUFFICIENTLY TO SLOW/STOP TEMP FALL THERE
TONIGHT. GIVEN THAT IT`S SUNNY IN THAT AREA NOW...AND SATELLITE
IMAGERY SHOWS NO TREND TO CLOUD UP SOON...TEMPS COULD PLUMMET
QUICKLY THIS EVENING. FCST WILL SHOW MINS IN THE MID TEENS...BUT
IT`S QUITE POSSIBLE TEMPS COULD FALL WELL DOWN INTO THE SINGLE
DIGITS DURING THE EVENING IF IT REMAINS MOSTLY CLEAR. MID 20S TO LWR
30S SHOULD BE THE RULE WED.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
LINGERING SURFACE TROUGH AND NORTHERN STREAM SHORTWAVE WILL BE
SLIDING EAST ACROSS EASTERN LAKE SUPERIOR ON WEDNESDAY EVENING WHILE
AN AREA OF HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES. WITH
900MB TEMPS STILL AROUND -12C AND ENOUGH LOW LEVEL MOISTURE BELOW
THE 3-4KFT INVERSION...SHOULD STILL SEE LOW CLOUDS ACROSS THE AREA
DURING THE EVENING IN THE NORTH-NORTHWEST WIND LOCATIONS. DURING THE
EVENING...WOULD EXPECT ISOLATED/SCATTERED SNOW SHOWERS IN THOSE SAME
WIND FAVORED LOCATIONS. WITH A LITTLE DEEPER MOISTURE OVER THE
EASTERN LOCATIONS...MAINLY FROM MUNISING EASTWARD...WOULD EXPECT
ISOLATED LIGHT SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT. OVER THE
WEST...THE INFLUENCE OF THE HIGH WILL ALLOW THE FLOW TO BECOME
ANTI-CYCLONIC THROUGH THE NIGHT AND INCREASE THE DRY AIR OVER THE
WESTERN LAKE...SLOWLY DECREASING THE CLOUDS IN THAT AREA. THIS
DECREASE IN CLOUDS LEADS TO UNCERTAINTY IN THE LOWS OVER THE WESTERN
CWA. WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF
NORMAL...LOCATIONS THAT DO CLEAR OUT WILL LIKELY FALL INTO THE
SINGLE DIGITS AND WOULDN/T BE SURPRISED TO SEE A FEW BELOW ZERO
READINGS IN THE COLD SPOTS OF EASTERN GOGEBIC AND IRON COUNTY.
THE HIGH WILL CONTINUE TO MOVE OVER THE AREA ON THURSDAY...CAUSING
WINDS TO BECOME MORE VARIABLE. WITH THE STRENGTHENING SUBSIDENCE
INVERSION...THE QUESTION FOR THURSDAY WILL BE WHERE THE CLOUDS WILL
BE LOCATED AND IF/WHEN THEY WILL MIX OUT. WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING WILL LIKELY EAT AWAY AT THE CLOUDS.
UPPER RIDGE BUILDS OVER THE AREA ON THURSDAY NIGHT INTO
FRIDAY...WHICH WILL KEEP THE AREA DRY AND ONLY PRODUCE SOME
MID-HIGH CLOUDS STREAMING ACROSS THE AREA. BY FRIDAY NIGHT...AN
UPPER TROUGH WILL BE SITTING OVER THE SOUTHWEST CONUS AND A
NORTHERN STREAM TROUGH WILL BE MOVING THROUGH
MANITOBA/SASKATCHEWAN. THE QUESTION BECOMES WHETHER THESE TWO
TROUGHS WILL SEPARATE OR STAY TOGETHER...WHICH THEN INFLUENCES THE
FORECAST INTO THE FIRST PART OF NEXT WEEK. THE LATEST TRENDS IN THE
12Z MODEL RUNS IS TO KEEP THE WAVES PHASED ENOUGH THROUGH THE
WEEKEND DUE TO A STRONGER NORTHERN STREAM WAVE. THIS IN TURN LEADS
TO STRONGER FORCING WITH THE SURFACE TROUGH MOVING THROUGH SATURDAY
INTO SATURDAY EVENING. WITH THIS STRONGER WAVE AND INCREASED
SOUTHERLY FLOW AHEAD OF THE SYSTEM...MODELS HAVE TRENDED UP WITH
THE QPF...ESPECIALLY OVER THE WESTERN HALF OF THE CWA. HAVE TRENDED
POPS UP FOR THIS PERIOD AND WITH SOME OF THE QPF AMOUNTS SHOWN ON
THE 12Z RUNS...COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS
OVER WESTERN UPPER MICHIGAN. WON/T MENTION THIS IN THE HWO AT THIS
POINT WITH THE WAY THE MODELS HAVE BEEN VARYING...BUT WILL BE
SOMETHING TO WATCH. FINALLY...LOOKING AT MODEL SOUNDINGS...THEY TRY
TO NOSE TEMPS ABOVE 0C AROUND 850MB OVER THE SOUTH CENTRAL WHICH
COULD LEAD TO SOME MELTING ALONG THE ISOTHERMAL LAYER TO THE
SURFACE. THUS...ADDED A MIX OF RAIN/SNOW TO THAT AREA.
HIGH PRESSURE WILL LIKELY BUILD INTO THE UPPER GREAT LAKES FOR
SUNDAY AND THE FIRST PART OF MONDAY...BEFORE THE NEARLY
CLOSED SOUTHERN STREAM TROUGH DRIFTS OUT OF THE SOUTHWEST CONUS.
WHILE THIS SYSTEM WAS LOOKING LIKE IT WAS GOING TO MOVE TOWARDS THE
UPPER GREAT LAKES ON THE 12Z RUNS YESTERDAY...THE LATEST TRENDS
HAVE IT MOVING MORE THROUGH THE OHIO RIVER VALLEY. THEREFORE...HAVE
TRENDED POPS DOWN FOR THE MONDAY PERIOD AND IF THE TREND CONTINUES
THEY MAY NEED TO BE REMOVED COMPLETELY.
AS FOR TEMPERATURES DURING THE LONG TERM PERIOD...IT LOOKS TO BE
FAIRLY NORMAL WITH A FEW DAYS OF SLIGHTLY ABOVE NORMAL HIGHS
THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 611 PM EST TUE MAR 5 2013
WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED
MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS
FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS THIS EVENING WITH
-SHSN DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR LATER TONIGHT
UNDER FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR
THIS EVENING BEFORE FALLING TO PREVAILING IFR LATER TONIGHT. AT
KSAW...IFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP THIS EVENING.
FAVORABLE CONVERGENT UPSLOPE FLOW OVERNIGHT WILL PROBABLY RESULT IN
CIGS FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER
WED MORNING OR AFTN.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EST TUE MAR 5 2013
NE TO N WINDS OF 15-25KT WILL BE THE RULE ACROSS LAKE SUPERIOR
TONIGHT...THOUGH 20-30KT WINDS WILL LINGER OVER THE WRN PORTION OF
THE LAKE INTO THE EVENING HRS BEFORE PRES GRADIENT BEGINS TO RELAX.
WINDS WILL FALL OFF TO UNDER 20KT OVER WRN LAKE SUPERIOR WED. OVER
ERN LAKE SUPERIOR...TIGHTER PRES GRADIENT WILL ALLOW 15-25KT WINDS
TO PERSIST INTO EARLY THU MORNING. HIGH PRES RIDGE PASSING OVER THE
AREA WILL THEN LEAD TO WINDS UNDER 20KT ACROSS THE LAKE THU/FRI.
ALTHOUGH A LOW PRES TROF WILL PASS ACROSS LAKE SUPERIOR LATER
SAT/EARLY SUN...PRES GRADIENT REMAINS WEAK...KEEPING WINDS MOSTLY
UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
357 PM EST MON MAR 4 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM EST MON MAR 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER THE
WRN DAKOTAS AND A DOWNSTREAM RIDGE OVER THE WRN GREAT LAKES. AT THE
SFC...A RIDGE EXTENDED FROM NRN MANITOBA AND NW ONTARIO INTO UPPER
MI BRINGING EASTERLY WINDS AND MAINLY CLEAR SKIES. CLOUDS ASSOCIATED
WITH THE BROAD AREA OF ISENTROPIC LIFT AHEAD OF THE SFC LOW VOER S
CNTRL N DAKOTA HAD SPREAD INTO FAR WRN UPPER MI WITH MAINLY ONLY
HIGH CLOUDS TO THE EAST.
MODELS WERE CONSISTENT IN TAKING THE DAKOTAS MID LEVEL LOW TO THE SE
TOWARD THE OH VALLEY BY TUE EVENING WITH BEST Q-VECT CONV AND
WAA/ISENTROPIC LIFT STAYING SE OF UPPER MI CLOSER TO THE TRACK OF
THE LOW AND ASSOC INVERTED SFC TROUGH. SO...MUCH OF THE CWA SHOULD
SEE LITTLE OR NO SYNOPTIC SCALE PCPN. CHANCE POPS STILL WERE
RETAINED OVER THE WEST WITH LITTLE IF ANY SNOW ACCUMULATION EXPECTED.
HOWEVER...HIGHER RES MODELS SUGGEST THAT AS NE FLOW STRENGTHENS AND
BECOMES MORE CYCLONIC PULLING 925-800 MB MOISTURE NE OF LAKE
SUPERIOR BACK INTO THE AREA...THE POTENTIAL FOR LAKE ENHANCED SNOW
INTO N CNTRL UPPER MI WILL INCREASE. WITH TEMPS NEAR THE 900 MB
INVERSION HEIGHT (NEAR 3K FT) ONLY AROUND -12C...BOTH INSTABILITY
AND SLR VALUES WILL BE MARGINAL FOR SIGNFICANT SNOW.
HOWEVER...UPSLOPE FLOW INTO THE HIGHER TERRAIN SHOULD BE ENOUGH TO
SUPPORT -SHSN BY TUE AFTERNOON WITH ACCUMULATIONS LESS THAN A HALF
INCH.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 356 PM EST MON MAR 4 2013
THE GENERALLY QUIET MARCH WEATHER CONTINUES THROUGH MUCH OF THE
LONG TERM PERIOD.
EXPECT SOME SNOW SHOWERS TO BE AFFECTING THE AREA
TUESDAY NIGHT INTO WEDNESDAY AS A LINGERING SURFACE TROUGH IS LEFT
BEHIND THE CLIPPER SYSTEM SLIDING TO THE SOUTH OF THE AREA TODAY
THROUGH TUESDAY. ALTHOUGH THE SYSTEM WILL BE TO THE SOUTH OF THE
AREA...DEEPER MOISTURE ROTATING WEST FROM THE LOW NEAR THE NEW
ENGLAND STATES WILL PROVIDE ENOUGH MOISTURE FOR SNOW TO DEVELOP
TUESDAY AFTERNOON INTO TUESDAY NIGHT. H850 TEMPERATURES OF -11C OVER
THE WEST AND -8C OVER THE EAST SHOULD BE COLD ENOUGH FOR LAKE
ENHANCEMENT...ESPECIALLY WITH THE ABUNDANT MOISTURE. IN
ADDITION...WITH THE LINGERING SURFACE TROUGH SLOWLY SLIDING ACROSS
THE AREA AND THE LEFTOVER NORTHERN STREAM SHORTWAVE AND ASSOCIATED
HEIGHT FALLS MOVING EAST ACROSS THE NORTHERN HALF OF THE
CWA...EXPECT A PERIOD OF LIGHT SNOW SHOWERS FOR THE WEST/CENTRAL
UPPER MICHIGAN TUESDAY NIGHT INTO WEDNESDAY. CYCLONIC
NORTH-NORTHEAST SFC-925 WINDS WOULD FAVOR THE NORTHWEST HALF OF
UPPER MICHIGAN FOR THE POPS. DID BUMP POPS UP SOME OVER THE
KEWEENAW FOR LATE TUESDAY NIGHT INTO WEDNESDAY MORNING...AS THERE
IS ADDITIONAL FORCING ALOFT FROM THE SHORTWAVE. SNOW RATIOS LOOK TO
BE ON THE LOW SIDE FOR MOST OF THE AREA...AT OR BELOW 10-1...SINCE
THE CLOUDS STRUGGLE TO GET ABOVE -10C. THERE IS A POTENTIAL FOR
SLIGHTLY HIGHER RATIOS OVER THE KEWEENAW DUE TO THE SYNOPTIC
FORCING...TOWARDS 15-1...BUT BEST FORCING LOOKS TO BE ABOVE THE DGZ
IN THAT AREA TO KEEP RATIOS FROM GETTING TOO HIGH. THE TROUGH
SLIDING EAST ON WEDNESDAY WILL TRANSITION THE LINGERING CLOUDS/SNOW
TO THE NORTHWEST WIND FAVORED LOCATIONS. MOST LOCATIONS WILL SEE A
LIGHT DUSTING OF SNOW BY WEDNESDAY EVENING...BUT SLIGHTLY HIGHER
AMOUNTS OF 1-2 INCHES ARE POSSIBLE OVER THE KEWEENAW AND THE HIGHER
TERRAIN OF MARQUETTE COUNTY.
THIS LINGERING TROUGH AND SHORTWAVE WILL SLIDE TO THE EAST OF THE
AREA ON WEDNESDAY...AS HIGH PRESSURE SLIDES EAST AND OVER THE UPPER
GREAT LAKES FOR WEDNESDAY NIGHT INTO THURSDAY BEFORE PUSHING EAST
ON FRIDAY. THIS HIGH SHOULD LEAD TO GRADUALLY DECREASING CLOUDS
DURING THAT PERIOD. ONCE AGAIN...THE POTENTIAL IS THERE FOR SOME
LINGERING FLURRIES OR STRATOCU STUCK BELOW THE INVERSION AROUND
2.5KFT. WILL PROBABLY BE SOMETHING SIMILAR TO THIS MORNINGS CLOUDS
FOR LOCATIONS FAVORED BY NORTH-NORTHWEST FLOW WEDNESDAY NIGHT INTO
THURSDAY. BUT WITH WINDS WEAKENING UNDER THE HIGH AND INCREASING DRY
AIR MOVING IN...WOULD THINK THAT THE LOW CLOUDS WOULD BE NEARLY GONE
ON THURSDAY NIGHT. WEDNESDAY NIGHT LOWS ARE TRICKY...SINCE THEY WILL
DEPEND ON WHERE THE CLOUDS ARE LOCATED. WHERE SKIES ARE
CLEAR...LIGHT WINDS AND PWAT VALUES TOWARDS 50 PERCENT OF NORMAL
WOULD LEAD TO GOOD RADIATIONAL COOLING. UPPER RIDGE WILL ALSO BUILD
OVER THE AREA DURING THIS TIME AND PRODUCE GRADUALLY WARMING
TEMPERATURES ALOFT...ESPECIALLY HEADING INTO THE WEEKEND AS
SOUTHERLY FLOW INCREASES WITH THE HIGH SLIDING TO THE EAST OF THE
AREA. THIS SHOULD TRANSITION THE AREA AWAY FROM THE BELOW NORMAL
TEMPERATURES THAT WE HAVE BEEN IN AND MORE NORMAL OR SLIGHT ABOVE
NORMAL HIGHS.
AS FOR PRECIPITATION HEADING INTO THE WEEKEND...THE CHANCES ALL
DEPEND ON THE STRENGTH OF THE UPPER RIDGE. THE FIRST SHORTWAVE WILL
RIDE UP THE UPPER RIDGE ON FRIDAY AND HEAD NORTHEAST TOWARDS JAMES
BAY ON FRIDAY NIGHT. 06Z GFS AND 00Z GEM HAVE IT FARTHER TO THE
SOUTHEAST AND MOVING ACROSS LAKE SUPERIOR...WHILE THE 00Z ECMWF
KEEPS IT WELL TO THE NORTHWEST IN ONTARIO. WITH THE SURFACE LOW
WELL TO THE NORTH OF THE AREA...SHOULD SEE A SURFACE TROUGH
PUSHING THROUGH THE AREA ON LATE FRIDAY NIGHT INTO SATURDAY. MODELS
VARYING ON TIMING AND AMOUNT OF MOISTURE ASSOCIATED WITH THE
SHORTWAVE AND THEN THE SURFACE TROUGH. THEY DO AGREE THAT DEEP
MOISTURE FOR WIDESPREAD SNOW SEEMS MARGINAL AND MORE LIKELY SEE
ISOLATED TO SCATTERED SNOW SHOWERS DURING THAT PERIOD.
UNCERTAINTY GROWS AFTER SATURDAY...AS THERE ARE LARGE MODEL AND
RUN-TO-RUN DIFFERENCES IN THE HANDLING OF THE UPPER LOW OVER THE
SOUTHWESTERN CONUS AND HOW THE NORTHERN AND SOUTHERN JET STREAMS
PHASE AS THE TROUGH SLIDES EAST. MODELS HAVE A DIFFICULT TIME WITH
PHASING SYSTEMS A DAY OR TWO OUT...SO DON/T HAVE ANY CONFIDENCE TO
GO MORE THAN A CONSENSUS CHANCE POPS FOR MONDAY WITH THE LOW MOVING
THROUGH THE GREAT LAKES. DESPITE THESE DIFFERENCES...BOTH THE LONGER
RANGE GFS/ECMWF DO SHOW THE UPPER TROUGH REESTABLISHING OVER THE
CENTRAL CONUS BY THE MIDDLE OF NEXT WEEK. THIS PRODUCES A POTENTIAL
FOR ANOTHER BELOW NORMAL TEMPERATURE PERIOD FOR THE UPPER GREAT
LAKES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1249 PM EST MON MAR 4 2013
EXPECT MVFR CIGS TO PERSIST AT CMX THROUGH THE AFTERNOON SUPPORTED
BY ENE ACROSS LAKE SUPERIOR. ALTHOUGH CONFIDENCE IS LIMITED...IMPROVEMENT
TO VFR IS EXPECTED THIS EVENING AS DRIER AIR UPSTREAM MOVES IN.
SATELLITE TRENDS AND FCST SOUNDINGS SUGGEST THAT CLOUDS SHOULD ERODE
AT SAW BY MID TO LATE AFTERNOON. INCREASING NE WINDS LATE TONIGHT
INTO TUE MORNING SHOULD AGAIN LEAD TO MVFR CIGS AT ALL TAF SITES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EST MON MAR 4 2013
AS LOW PRESSURE OVE THE DAKOTAS SLIDES TO THE SE...NE WINDS TO 30
KTS ARE EXPECTED MON NIGHT THROUGH TUE...ESPECIALLY OVER THE WRN
THIRD OF THE LAKE WHERE LOW LEVEL CONV IS STRONGEST. NORTH WINDS TO 25 KTS
CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY WINDS AND COLDER
TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT TIMES THROUGH
WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS LATER
WEDNESDAY INTO FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1249 PM EST MON MAR 4 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 501 AM EST MON MAR 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A VIGOROUS SHORTWAVE TROUGH
OVER ERN MONTANA WITH A MID/UPPER LEVEL RIDGE EXTENDING FROM THE
PLAINS INTO THE UPPER GREAT LAKES. AT THE SFC...A RIDGE EXTENDED
FROM NRN MANITOBA INTO WRN UPPER MI. SHALLOW LOW-LVL MOISTURE AIDED
BY CONTRIBUTION OFF LAKE SUPERIOR IN NNE FLOW HAS GENERATED SOME
LAKE CLOUDS FOR AREAS EAST OF MQT. LACK OF RADAR RETURNS EARLY THIS
MORNING SUGGEST LTL MORE THAN FLURRIES ASSOC WITH THESE LAKE CLOUDS.
CLEAR SKIES OVER THE WEST HALF HAS RESULTED IN TEMPS FALLING INTO
THE SINGLE DIGITS BLO ZERO AT MANY LOCATIONS EARLY THIS MORNING.
TODAY...WEAK UPSLOPE NE FLOW INTO N CNTRL UPPER MI MAY GENERATE SOME
FLURRIES DESPITE INVERSION HEIGHTS BELOW 3K FT. WITH LOW CONFIDENCE
IN ANY MEASURABLE LES...HAVE DROPPED MENTION OF SLIGHT CHANCE POPS.
WITH ANTICYCLONIC/DIFLUENT ENE FLOW...ANY FLURRIES THAT FORM SHOULD
END BY MIDDAY. LOOK FOR MAX TEMPS TO REBOUND INTO THE UPPER 20S AND
LOWER 30S...PER FCST SOUNDINGS LOW LEVEL TEMP PROFILE.
TONIGHT...MODELS CONSISTENT IN SHOWING ERN MT SHORTWAVE DIVING WELL
SE OF THE UPPER GREAT LAKES LATER TONIGHT. WITH BEST Q-VECT CONV AND
WAA/ISENTROPIC LIFT STAYING GENERALLY SE OF FCST AREA ALONG TRACK OF
SHORTWAVE AND ASSOC INVERTED SFC TROUGH...MUCH OF CWA SHOULD STAY
DRY THROUGH TONIGHT UNDER INFLUENCE OF SFC HIGH PRESSURE RIDGE. KEPT
ONLY SLIGHT CHC POPS IN FCST OVER FAR WRN LAKE SUPERIOR LATE
TONIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 501 AM EST MON MAR 4 2013
AT 12Z TUE AN UPPER ANS SFC RIDGE WILL BE OVER THE ERN CWA...BUT
WILL SHIFT E AS AN UPPER TROUGH MOVES IN FROM THE W. THE UPPER
TROUGH WILL MOVE E OF THE CWA BY 00Z THU...BRINGING IN COLDER
INVERSION TOP TEMPS...BETTER SYNOPTIC LIFT AND MORE CYCLONIC
FLOW...WHICH WILL SUPPORT INCREASED LES WITH NE-N LOW LEVEL WINDS
TUE INTO THU. THE BEST COVERAGE AND INTENSITY OF LES IS EXPECTED
TUE/TUE NIGHT...BUT WILL STILL NOT BE ALL THAT HEAVY DUE TO MARGINAL
CONDITIONS AND LOW SNOW TO LIQUID RATIOS. THE SOUTHERN PART OF THE
UPPER TROUGH WILL BE CLOSED OFF AND WILL MOVE WELL S OF THE CWA ON
TUE...WITH SOME SYNOPTIC SNOW POSSIBLY CLIPPING THE IRONWOOD AREA
TUE...BUT ONLY MINOR SNOWFALL AMOUNTS WOULD BE POSSIBLE. WOULD
EXPECT LES TO TAPER OFF AND END WHEN WINDS TURN SLY THU AS A SFC
RIDGE MOVES THROUGH...BUT WARMING TEMPS AND ANTICYCLONIC FLOW WILL
KEEP LES FROM FORMING OFF LAKE MICHIGAN.
EXPECT A COUPLE OF SHORTWAVES TO MOVE NEARBY FRI AND SAT...BUT DO
NOT EXPECT MUCH IN THE WAY OF PRECIP...ESPECIALLY WHEN LOOKING AT
THE MORE CONTINUITOUS ECMWF AND GEM MODELS AS THE GFS DOES PUMP OUT
A GOOD AMOUNT OF PRECIP SAT INTO SUN. PREFERRED THE NON-GFS
SOLUTIONS FOR THIS PART OF THE FORECAST. THEN EXPECT SFC RIDGING TO
MOVE IN ON SUN.
TEMPS WILL GENERALLY BE ON THE RISE...WITH HIGHS AOA FREEZING IN
MOST LOCATIONS FROM THU ON. FOR THE WEEKEND...HIGH TEMPS WILL BE
AROUND 40 DEGREES ALONG THE WI BORDER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1249 PM EST MON MAR 4 2013
EXPECT MVFR CIGS TO PERSIST AT CMX THROUGH THE AFTERNOON SUPPORTED
BY ENE ACROSS LAKE SUPERIOR. ALTHOUGH CONFIDENCE IS LIMITED...IMPROVEMENT
TO VFR IS EXPECTED THIS EVENING AS DRIER AIR UPSTREAM MOVES IN.
SATELLITE TRENDS AND FCST SOUNDINGS SUGGEST THAT CLOUDS SHOULD ERODE
AT SAW BY MID TO LATE AFTERNOON. INCREASING NE WINDS LATE TONIGHT
INTO TUE MORNING SHOULD AGAIN LEAD TO MVFR CIGS AT ALL TAF SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 501 AM EST MON MAR 4 2013
STRONGEST WINDS THIS WEEK OCCUR THIS AFTERNOON THROUGH TUESDAY OVER
FAR WESTERN LAKE SUPERIOR AS A LOW PRESSURE SYSTEM MOVES JUST TO THE
SOUTH. EAST-NORTHEAST WINDS TO 30 KTS ARE A GOOD BET. MAY BE GALE
GUSTS TOWARD THE HEAD OF LK SUPERIOR AND ALONG THE MINNESOTA SHORE
MONDAY NIGHT INTO TUESDAY MORNING DUE TO COASTAL CONVERGENCE. NORTH
WINDS TO 25 KTS CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY
WINDS AND COLDER TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT
TIMES THROUGH WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS
LATER WEDNESDAY INTO FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
658 AM EST MON MAR 4 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 501 AM EST MON MAR 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A VIGOROUS SHORTWAVE TROUGH
OVER ERN MONTANA WITH A MID/UPPER LEVEL RIDGE EXTENDING FROM THE
PLAINS INTO THE UPPER GREAT LAKES. AT THE SFC...A RIDGE EXTENDED
FROM NRN MANITOBA INTO WRN UPPER MI. SHALLOW LOW-LVL MOISTURE AIDED
BY CONTRIBUTION OFF LAKE SUPERIOR IN NNE FLOW HAS GENERATED SOME
LAKE CLOUDS FOR AREAS EAST OF MQT. LACK OF RADAR RETURNS EARLY THIS
MORNING SUGGEST LTL MORE THAN FLURRIES ASSOC WITH THESE LAKE CLOUDS.
CLEAR SKIES OVER THE WEST HALF HAS RESULTED IN TEMPS FALLING INTO
THE SINGLE DIGITS BLO ZERO AT MANY LOCATIONS EARLY THIS MORNING.
TODAY...WEAK UPSLOPE NE FLOW INTO N CNTRL UPPER MI MAY GENERATE SOME
FLURRIES DESPITE INVERSION HEIGHTS BELOW 3K FT. WITH LOW CONFIDENCE
IN ANY MEASURABLE LES...HAVE DROPPED MENTION OF SLIGHT CHANCE POPS.
WITH ANTICYCLONIC/DIFLUENT ENE FLOW...ANY FLURRIES THAT FORM SHOULD
END BY MIDDAY. LOOK FOR MAX TEMPS TO REBOUND INTO THE UPPER 20S AND
LOWER 30S...PER FCST SOUNDINGS LOW LEVEL TEMP PROFILE.
TONIGHT...MODELS CONSISTENT IN SHOWING ERN MT SHORTWAVE DIVING WELL
SE OF THE UPPER GREAT LAKES LATER TONIGHT. WITH BEST Q-VECT CONV AND
WAA/ISENTROPIC LIFT STAYING GENERALLY SE OF FCST AREA ALONG TRACK OF
SHORTWAVE AND ASSOC INVERTED SFC TROUGH...MUCH OF CWA SHOULD STAY
DRY THROUGH TONIGHT UNDER INFLUENCE OF SFC HIGH PRESSURE RIDGE. KEPT
ONLY SLIGHT CHC POPS IN FCST OVER FAR WRN LAKE SUPERIOR LATE
TONIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 501 AM EST MON MAR 4 2013
AT 12Z TUE AN UPPER ANS SFC RIDGE WILL BE OVER THE ERN CWA...BUT
WILL SHIFT E AS AN UPPER TROUGH MOVES IN FROM THE W. THE UPPER
TROUGH WILL MOVE E OF THE CWA BY 00Z THU...BRINGING IN COLDER
INVERSION TOP TEMPS...BETTER SYNOPTIC LIFT AND MORE CYCLONIC
FLOW...WHICH WILL SUPPORT INCREASED LES WITH NE-N LOW LEVEL WINDS
TUE INTO THU. THE BEST COVERAGE AND INTENSITY OF LES IS EXPECTED
TUE/TUE NIGHT...BUT WILL STILL NOT BE ALL THAT HEAVY DUE TO MARGINAL
CONDITIONS AND LOW SNOW TO LIQUID RATIOS. THE SOUTHERN PART OF THE
UPPER TROUGH WILL BE CLOSED OFF AND WILL MOVE WELL S OF THE CWA ON
TUE...WITH SOME SYNOPTIC SNOW POSSIBLY CLIPPING THE IRONWOOD AREA
TUE...BUT ONLY MINOR SNOWFALL AMOUNTS WOULD BE POSSIBLE. WOULD
EXPECT LES TO TAPER OFF AND END WHEN WINDS TURN SLY THU AS A SFC
RIDGE MOVES THROUGH...BUT WARMING TEMPS AND ANTICYCLONIC FLOW WILL
KEEP LES FROM FORMING OFF LAKE MICHIGAN.
EXPECT A COUPLE OF SHORTWAVES TO MOVE NEARBY FRI AND SAT...BUT DO
NOT EXPECT MUCH IN THE WAY OF PRECIP...ESPECIALLY WHEN LOOKING AT
THE MORE CONTINUITOUS ECMWF AND GEM MODELS AS THE GFS DOES PUMP OUT
A GOOD AMOUNT OF PRECIP SAT INTO SUN. PREFERRED THE NON-GFS
SOLUTIONS FOR THIS PART OF THE FORECAST. THEN EXPECT SFC RIDGING TO
MOVE IN ON SUN.
TEMPS WILL GENERALLY BE ON THE RISE...WITH HIGHS AOA FREEZING IN
MOST LOCATIONS FROM THU ON. FOR THE WEEKEND...HIGH TEMPS WILL BE
AROUND 40 DEGREES ALONG THE WI BORDER.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 644 AM EST MON MAR 4 2013
VFR CONDITIONS AT KSAW AND KCMX WILL GIVE WAY TO MVFR CIGS BY LATE
MORNING AS AN E-NE FLOW BRINGS MASS OF STRATOCU LAKE CLOUDS INLAND.
MODEL FCST SOUNDINGS SUGGEST THESE CLOUDS COULD PERSIST THROUGH REST
OF TAF PD IN CONTINUED E-NE FLOW. AT KIWD...MID LVL CLOUDS WILL MOVE
IN THIS MORNING AND CLOUDS WILL CONTINUE TO LOWER TONIGHT AS SYSTEM
OVER THE NRN PLAINS BRUSHES JUST SOUTH AND WEST OF THE REGION.
HOWEVER...EXPECT VFR CONDITIONS TO PERSIST THROUGH THE PD AT KIWD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 501 AM EST MON MAR 4 2013
STRONGEST WINDS THIS WEEK OCCUR THIS AFTERNOON THROUGH TUESDAY OVER
FAR WESTERN LAKE SUPERIOR AS A LOW PRESSURE SYSTEM MOVES JUST TO THE
SOUTH. EAST-NORTHEAST WINDS TO 30 KTS ARE A GOOD BET. MAY BE GALE
GUSTS TOWARD THE HEAD OF LK SUPERIOR AND ALONG THE MINNESOTA SHORE
MONDAY NIGHT INTO TUESDAY MORNING DUE TO COASTAL CONVERGENCE. NORTH
WINDS TO 25 KTS CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY
WINDS AND COLDER TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT
TIMES THROUGH WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS
LATER WEDNESDAY INTO FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
502 AM EST MON MAR 4 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 501 AM EST MON MAR 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A VIGOROUS SHORTWAVE TROUGH
OVER ERN MONTANA WITH A MID/UPPER LEVEL RIDGE EXTENDING FROM THE
PLAINS INTO THE UPPER GREAT LAKES. AT THE SFC...A RIDGE EXTENDED
FROM NRN MANITOBA INTO WRN UPPER MI. SHALLOW LOW-LVL MOISTURE AIDED
BY CONTRIBUTION OFF LAKE SUPERIOR IN NNE FLOW HAS GENERATED SOME
LAKE CLOUDS FOR AREAS EAST OF MQT. LACK OF RADAR RETURNS EARLY THIS
MORNING SUGGEST LTL MORE THAN FLURRIES ASSOC WITH THESE LAKE CLOUDS.
CLEAR SKIES OVER THE WEST HALF HAS RESULTED IN TEMPS FALLING INTO
THE SINGLE DIGITS BLO ZERO AT MANY LOCATIONS EARLY THIS MORNING.
TODAY...WEAK UPSLOPE NE FLOW INTO N CNTRL UPPER MI MAY GENERATE SOME
FLURRIES DESPITE INVERSION HEIGHTS BELOW 3K FT. WITH LOW CONFIDENCE
IN ANY MEASURABLE LES...HAVE DROPPED MENTION OF SLIGHT CHANCE POPS.
WITH ANTICYCLONIC/DIFLUENT ENE FLOW...ANY FLURRIES THAT FORM SHOULD
END BY MIDDAY. LOOK FOR MAX TEMPS TO REBOUND INTO THE UPPER 20S AND
LOWER 30S...PER FCST SOUNDINGS LOW LEVEL TEMP PROFILE.
TONIGHT...MODELS CONSISTENT IN SHOWING ERN MT SHORTWAVE DIVING WELL
SE OF THE UPPER GREAT LAKES LATER TONIGHT. WITH BEST Q-VECT CONV AND
WAA/ISENTROPIC LIFT STAYING GENERALLY SE OF FCST AREA ALONG TRACK OF
SHORTWAVE AND ASSOC INVERTED SFC TROUGH...MUCH OF CWA SHOULD STAY
DRY THROUGH TONIGHT UNDER INFLUENCE OF SFC HIGH PRESSURE RIDGE. KEPT
ONLY SLIGHT CHC POPS IN FCST OVER FAR WRN LAKE SUPERIOR LATE
TONIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 501 AM EST MON MAR 4 2013
AT 12Z TUE AN UPPER ANS SFC RIDGE WILL BE OVER THE ERN CWA...BUT
WILL SHIFT E AS AN UPPER TROUGH MOVES IN FROM THE W. THE UPPER
TROUGH WILL MOVE E OF THE CWA BY 00Z THU...BRINGING IN COLDER
INVERSION TOP TEMPS...BETTER SYNOPTIC LIFT AND MORE CYCLONIC
FLOW...WHICH WILL SUPPORT INCREASED LES WITH NE-N LOW LEVEL WINDS
TUE INTO THU. THE BEST COVERAGE AND INTENSITY OF LES IS EXPECTED
TUE/TUE NIGHT...BUT WILL STILL NOT BE ALL THAT HEAVY DUE TO MARGINAL
CONDITIONS AND LOW SNOW TO LIQUID RATIOS. THE SOUTHERN PART OF THE
UPPER TROUGH WILL BE CLOSED OFF AND WILL MOVE WELL S OF THE CWA ON
TUE...WITH SOME SYNOPTIC SNOW POSSIBLY CLIPPING THE IRONWOOD AREA
TUE...BUT ONLY MINOR SNOWFALL AMOUNTS WOULD BE POSSIBLE. WOULD
EXPECT LES TO TAPER OFF AND END WHEN WINDS TURN SLY THU AS A SFC
RIDGE MOVES THROUGH...BUT WARMING TEMPS AND ANTICYCLONIC FLOW WILL
KEEP LES FROM FORMING OFF LAKE MICHIGAN.
EXPECT A COUPLE OF SHORTWAVES TO MOVE NEARBY FRI AND SAT...BUT DO
NOT EXPECT MUCH IN THE WAY OF PRECIP...ESPECIALLY WHEN LOOKING AT
THE MORE CONTINUITOUS ECMWF AND GEM MODELS AS THE GFS DOES PUMP OUT
A GOOD AMOUNT OF PRECIP SAT INTO SUN. PREFERRED THE NON-GFS
SOLUTIONS FOR THIS PART OF THE FORECAST. THEN EXPECT SFC RIDGING TO
MOVE IN ON SUN.
TEMPS WILL GENERALLY BE ON THE RISE...WITH HIGHS AOA FREEZING IN
MOST LOCATIONS FROM THU ON. FOR THE WEEKEND...HIGH TEMPS WILL BE
AROUND 40 DEGREES ALONG THE WI BORDER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 119 AM EST MON MAR 4 2013
VFR CONDITIONS WILL PREVAIL THROUGH THE FCST PERIOD WITH A SURFACE
RIDGE DOMINATING THE WEATHER IN THE NORTHERN GREAT LAKES. ONLY
EXCEPTION WILL BE AT SAW WITH SOME LAKE EFFECT UPSLOPE MVFR CLOUDS
IN FOR THIS MORNING...BEFORE BURNING OFF AGAIN IN THE AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 501 AM EST MON MAR 4 2013
STRONGEST WINDS THIS WEEK OCCUR THIS AFTERNOON THROUGH TUESDAY OVER
FAR WESTERN LAKE SUPERIOR AS A LOW PRESSURE SYSTEM MOVES JUST TO THE
SOUTH. EAST-NORTHEAST WINDS TO 30 KTS ARE A GOOD BET. MAY BE GALE
GUSTS TOWARD THE HEAD OF LK SUPERIOR AND ALONG THE MINNESOTA SHORE
MONDAY NIGHT INTO TUESDAY MORNING DUE TO COASTAL CONVERGENCE. NORTH
WINDS TO 25 KTS CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY
WINDS AND COLDER TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT
TIMES THROUGH WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS
LATER WEDNESDAY INTO FRIDAY AS HIGH PRESSURE CROSSES THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
126 AM EST MON MAR 4 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 350 PM EST SUN MAR 3 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A VIGOROUS SHORTWAVE TROUGH
OVER NRN MONTANA...A MID/UPPER LEVEL RIDGE OVER THE PLAINS AND NE
CANADA AND TROUGHING OVER NRN MANTIOBA AND THE SE CONUS LEAVING A
COL OVER THE NRN GREAT LAKES. AT THE SFC...A RIDGE EXTENDED FROM NW
ONTARIO THROUGH WRN UPPER MI INTO WI AND IL. SIMILAR TO
YESTERDAY...LES AND CLOUDS HAVE DIMINISHED DURING THE AFTERNOON AS
DAYTIME MIXING AND VERY DRY AIS UPSTREAM HELPS ERODE THE
CLOUD BANDS.
TONIGHT AND MON...ALSO SIMILAR TO PREVIOUS FEW NIGHTS...EXPECT SOME LES
TO REDEVLOP OVERNIGHT AS UPSTREAM MIXING/DRYING SUBSIDES AND LAND
BREEZES DEVELOP. HOWEVER...HIGH RES MODELS SUGGEST THAT LOW LEVEL
CONV WILL BE WEAKER THAN LAST NIGHT WITH MAINLY DIFLUENT ACYC FLOW
OVER THE THE WEST HALF OF LAKE SUPERIOR. WEAK UPSLOPE FLOW INTO N
CNTRL UPPER MI SHOULD HELP PRODUCE AT LEAST SOME FLURRIES EVEN WITH
INVERSION HEIGHTS AT OR BELOW 2K-3K FT. WITH LOW CONFIDENCE IN EVEN
ANY LIGHT MEASURABLE LES...FCST RETAINED PREV MENTION OF SLIGHT
CHANCE POPS. FAVORABLE RADIATIONAL COOLING CONDITIONS INLAND SHOULD
WILL ALLOW TEMPS TO DROP TO LOWER END OF GUIDANCE WITH READINGS IN
THE 0 TO 10 BELOW ZERO RANGE.
AS ACYC WINDS BACK TO THE ENE...EXPECT REMAINING LES/FLURRIES TO END
BY MIDDAY MON. TEMPS SHOULD REBOUND TO READINGS CLOSER TO SEASONAL
AVERAGES NEAR 30...PER FCST SOUNDINGS LOW LEVEL TEMP PROFILE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 PM EST SUN MAR 3 2013
FOCUS INITIALY IS ON SHORTWAVE TROUGH DIGGING SOUTHEAST ACROSS
NORTHERN PLAINS. CONVERGENCE AND MOISTURE ADVECTION ALONG AND
NORTH OF SFC/H85/H7 LOWS AND DIVERGENCE ALOFT FROM H25 JET STREAK
SHOULD BE SUPPORTING SWATH OF MODERATE TO HEAVY SNOW FROM EASTERN
NORTH DAKOTA THROUGH MOST OF MINNESOTA AND INTO SOUTHERN WISCONSIN.
H85-H7 FRONTOGENESIS AND H85 MOISTURE STAY FAR ENOUGH TO SOUTH TO
KEEP NORTHERN EDGE OF SNOW SHIELD OUT OF CWA MONDAY NIGHT. H7-H6
FRONTOGENESIS AND INCREASING 1000-700MB MOISTURE PROBABLY WILL ALLOW
SYSTEM SNOW TO CLIP FAR WEST TUESDAY. KIWD WOULD SEE BEST CHANCE OF
SEEING THIS SYSTEM SNOW. FARTHER NORTH...EXPECT INCREASING LIGHT
SNOW MAINLY DUE TO WINDS BECOMING MORE NORTHEAST AND WITH INCREASING
925-850MB MOISTURE. THE ADDITIONAL MOISTURE ALONG WITH FLOW OFF LK
SUPERIOR AND MINOR COOLING AT TOP OF INVERSION TO AROUND -12C WILL
BE SUFFICIENT TO RESULT IN LAKE ENHANCED SNOW. GIVEN THE PERSISTENT
LIGHT LK EFFECT SEEN OFF AND ON OVER NCNTRL UPR MICHIGAN SINCE
THURSDAY WITH QUITE MARGINAL CONDITIONS IN TERMS OF INVERSION
HEIGHT/TEMPS...PRETTY CONFIDENT SNOW WILL OCCUR TUESDAY/TUESDAY
NIGHT/WEDNESDAY MORNING. TOTAL SNOW ACCUMULATIONS WILL BE LIMITED
GIVEN ABSENCE OF LARGER SCALE FORCING AND WITH MAJORITY OF LIFT
OCCURRING AT TEMPS WARMER THAN -10C LEADING TO SLR/S LESS THAN 10:1.
EVEN SO...SOME HIGHER TERRAIN AREAS OVER FAR WESTERN UPR MICHIGAN
AND IN NCNTRL UPR MICHIGAN MAY END UP WITH A FEW INCHES OF SNOW BY
LATER WEDNESDAY.
H925 TEMPS AROUND -10C WITH WEAK NORTHERLY WINDS AND SUFFICIENT
MOISTURE BLO INVERSION WILL RESULT IN LIGHT LK EFFECT PERSISTING
THROUGH LATE WEDNESDAY. SINCE SFC-H925MB WINDS DO NOT BECOME MORE
SOUTHERLY UNTIL THURSDAY MORNING...LIGHT LK EFFECT/FLURRIES PROBABLY
WILL LINGER ALONG PORTIONS OF LK SUPERIOR SHORE WEDNESDAY NIGHT. BY
TIME WINDS DO BECOME MORE SOUTHERLY...TEMPS ARE FURTHER WARMING...SO
DO NOT EXPECT ANY LK EFFECT OFF LK MICHIGAN. COULD BE ENHANCEMENT TO
CLOUDS THOUGH WHICH WOULD TEMPER WARMING ON THURSDAY FOR THE EAST.
H5 RIDGE BUILDS FROM CNTRL CONUS ACROSS GREAT LAKES THURSDAY INTO
FRIDAY. BY LATER FRIDAY...TROUGH OVER WESTERN CONUS SPLITS LEAVING
SEPARATE SOUTHERN STREAM TROUGH OVER SOUTHWEST CONUS AND NORTHERN
STREAM TROUGH PUSHING ACROSS SCNTRL CANADA. SFC-H85 TROUGHING FORMS
IN RESPONSE OVER THE NORTEHRN PLAINS WHICH INCREASES SOUTHERLY
WINDS OVER UPR LAKES THURSDAY NIGHT INTO FRIDAY. WINDS MAY BECOME
BREEZY WITH GUSTS OVER 20 MPH...BUT LACK OF STRONGER PRESSURE
GRADIENT WILL KEEP REAL STRONG WINDS FROM OCCURRING.
GFS INDICATES STRONGER NORTHERN STREAM DYNAMICS HEAD EAST QUICKLY ON
FRIDAY WHILE OUTRUNNING THE SFC TROUGH...SO THE TROUGH REALLY LOSES
ITS PUNCH AS IT MOVES ACROSS THE AREA. ECMWF FAIRLY SIMILAR WITH
OVERALL IDEA. SHOULD NOTE THAT THE GEM-NH A BIT STRONGER/FARTHER
SOUTH WITH NORTHERN STREAM WAVE SO IT GENERATES MORE QPF IN WARM AIR
ADVECTION AHEAD OF THE WAVE ON FRIDAY. GFS TRYING TO GENERATE SOME
LGT DRIZZLE LIKE PRECIP ON FRIDAY WITH LOW-LEVEL MOISTURE BENEATH
DRIER AIR IN MID LEVELS. THINK THAT LACK OF DEEPER MOISTURE INTO THE
SYSTEM SUGGESTS THAT NOT MUCH PRECIPITATION WILL OCCUR ON FRIDAY.
WILL NOT ALTER SLIGHT CHANCE POPS FROM CONSENSUS OF MODELS. SOME
INDICATION THAT AS WARMING KICKS IN ABOVE H9 AHEAD OF THE
TROUGH...LOW-LEVEL MOISTURE MAY REMAIN TRAPPED BENEATH THE INVERSION
OVER MUCH OF CWA RIGHT THROUGH FRIDAY. MAIN IMPACT WILL BE ON TEMPS
THURSDAY THROUGH FRIDAY. DUE TO STRICT TEMPERATURE ADVECTION WOULD
THINK MANY AREAS THURSDAY AND FRIDAY WILL STILL BE ABLE TO CRACK THE
FREEZING MARK.
MODELS NOT AS COLD IN WAKE OF FRONT NEXT WEEKEND AS THEY HAVE SHOWED
LAST COUPLE DAYS. ULTIMATELY MAY END UP BEING DRY NEXT WEEKEND /JUST
HAVE SLIGHT CHANCES IN THERE/ WITH TEMPERATURES SIMILAR TO LATE THIS
WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 119 AM EST MON MAR 4 2013
VFR CONDITIONS WILL PREVAIL THROUGH THE FCST PERIOD WITH A SURFACE
RIDGE DOMINATING THE WEATHER IN THE NORTHERN GREAT LAKES. ONLY
EXCEPTION WILL BE AT SAW WITH SOME LAKE EFFECT UPSLOPE MVFR CLOUDS
IN FOR THIS MORNING...BEFORE BURNING OFF AGAIN IN THE AFTERNOON.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 350 PM EST SUN MAR 3 2013
STRONGEST WINDS THIS WEEK OCCUR MONDAY AFTERNOON THROUGH TUESDAY
OVER FAR WESTERN LAKE SUPERIOR AS LOW PRESSURE SYSTEM MOVES BY JUST
TO THE SOUTH. EAST-NORTHEAST WINDS TO 30 KTS GOOD BET. MAY BE GALE
GUSTS TOWARD THE HEAD OF LK SUPERIOR AND ALONG THE MINNESOTA SHORE
MONDAY NIGHT INTO TUESDAY MORNING DUE TO COASTAL CONVERGENCE. NORTH
WINDS TO 25 KTS CONTINUE THROUGH TUESDAY NIGHT. DUE TO THE GUSTY
WINDS AND COLDER TEMPERATURES...FREEZING SPRAY WILL BE AROUND AT
TIMES THROUGH WEDNESDAY MORNING. WINDS DIMINISH TO LESS THAN 20 KTS
LATER WEDNESDAY AND THURSDAY AS HIGH PRESSURE CROSSES THE REGION.
SOUTH WINDS TO 25 KTS POSSIBLE THURSDAY NIGHT INTO FRIDAY OUT AHEAD
OF LOW PRESSURE TROUGH. TROUGH MOVES THROUGH FRIDAY NIGHT BUT
WEST-NORTHWEST WINDS IN WAKE OF TROUGH SHOULD STAY BLO 20 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...VOSS
MARINE...JLA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
635 PM CST TUE MAR 5 2013
.UPDATE...
00Z AVIATION DISCUSSION ADDED BELOW.
&&
.PREV DISCUSSION...
/ISSUED 234 PM CST TUE MAR 5 2013/
TONIGHT...COMPACT SFC LOW OVER ERN IA WILL CONTINUE TO DRIFT SE TWD
THE PRIMARY LOW PRES CENTER OVER THE LOWER MISSISSIPPI RIVER VALLEY.
ELONGATED SFC TROF FROM FAR NW MN THRU S-CENTRAL MN INTO NE IA AND
NW IL WILL ALSO SLOWLY DRIFT EWD TNGT WHILE THE CUTOFF UPPER LOW
SHIFTS FROM CENTRAL IA INTO SRN IL AND CENTRAL KY. THE DEPARTURE OF
THIS OVERALL COMPLEX WILL NOT ONLY ALLOW THE SNOWFALL OVER ERN
PORTIONS OF THE MPX COVERAGE AREA TO COME TO AN END /ALREADY HAS
OVER THE WRN HALF/...BUT WILL ALSO ALLOW WINDS TO GRADUALLY SETTLE
DOWN AS HIGH PRES SLOWLY MAKES INROADS TO THE AREA FROM THE NW. AS
UPPER LEVEL FLOW BECOMES NW AND SFC HIGH PRES ARRIVES FROM S-CENTRAL
CANADA...PARTIALLY CLEARING SKIES AND DIMINISHING WINDS COMBINED
WITH PRONOUNCED CAA WILL ALLOW LOWS TO DROP WELL INTO THE SINGLE
DIGITS FOR MUCH OF THE COVERAGE AREA TNGT.
COOL HIGH PRESSURE SETTLES IN FOR WEDNESDAY...WITH MOSTLY SUNNY
SKIES...LIGHT WINDS...AND TEMPERATURES MOSTLY IN THE 20S FOR
HIGHS. WEDNESDAY NIGHT WILL BE CHILLY UNDER THE CONTINUED
INFLUENCE OF THE RIDGE AND WITH THE RECENTLY REVIVED SNOWPACK. LOWS
WILL DIP INTO THE SINGLE DIGITS ACROSS NEARLY ALL OF THE FORECAST
AREA...WITH A FEW SUB-ZERO READINGS NOT OUT OF THE QUESTION IN
WEST CENTRAL WISCONSIN FROM AMERY TO LADYSMITH.
ON THURSDAY...SOUTHEASTERLY FLOW STRENGTHENS AS A STRENGTHENING
SOUTHWEST CONUS TROUGH WORKS TO FLATTEN THE CENTRAL CONUS RIDGE. A
SECONDARY TROUGH OF NORTHERN STREAM ORIGIN JOINS IN ON THE EFFORT
OVER THE WEEKEND. FAIRLY STRONG ISENTROPIC UPGLIDE AND LOWERING
CONDENSATIONAL PRESSURE DEFICITS ARE PROGGED TO OVERSPREAD THE
FORECAST AREA ON FRIDAY NIGHT INTO SATURDAY...WITH FAIRLY DECENT
AGREEMENT BETWEEN THE 05.12Z GFS AND 05.12Z ECMWF MODELS. THE
INITIAL CONCERN WITH THIS SYSTEM WILL BE THE POTENTIAL FOR MIXED
PRECIP...INCLUDING FREEZING RAIN ON FRIDAY/SATURDAY NIGHTS...WITH
THE 540 THICKNESS LINE PROGGED AS FAR NORTH AS CENTRAL MN.
THE DILEMMA SURROUNDING WHAT WILL BECOME OF THE WESTERN TROUGH AS
IT CROSSES THE CENTRAL CONUS HAS SEEMINGLY BECOME MORE CLEAR WITH
THE 12Z MODEL RUNS. NAMELY...WITH THE 12Z ECMWF WHICH FELL IN LINE
WITH THE MODEL CONSENSUS IN KEEPING IT AS A MORE PROGRESSIVE/OPEN WAVE AS
IT TRACKED TO THE EASTERN CONUS /IN CONTRAST WITH THE 00Z ECMWF
WHICH HAD DEPICTED A RELATIVELY MAJOR PRECIP EVENT FOR THE AREA
EARLY NEXT WEEK/. WOULD LIKE TO HAVE ENTIRELY REMOVED POPS FROM
THE SUNDAY AND MONDAY PORTION OF THE FORECAST PERIOD...BUT THE 12Z
FIM STILL HINTED TOWARD THE STRONGER SOLUTION...SO RETAINED A 20
POP FROM SOUTHERN MN NORTHEAST TOWARD EAU CLAIRE FOR SUNDAY AND
SUNDAY NIGHT.
HIGH TEMPERATURES WILL GENERALLY RANGE FROM THE UPPER 20S TO MID
30S NEXT WEEK...WITH SLIGHTLY REDUCING HEIGHTS AS SEMI-ZONAL FLOW
DEVELOPS IN THE WAKE OF THE TROUGH.
&&
.AVIATION.../00Z TAF ISSUANCE/
SNOW IS QUICKLY WINDING DOWN AND IS TAKING ON MORE OF A CONVECTIVE
SNOW SHOWER NATURE FOR SITES FROM STC ON EAST AS SFC LOW NOW PULLS
INTO ERN KENTUCKY. NOT EXPECTING SNOW TO LAST MUCH MORE THAN AN
HOUR OR TWO THOUGH. IN THE WAKE OF THE SNOW...COMPLEX CLOUD
SCENARIO LOOKS TO BE SETTING UP AS SUBSIDENCE STARTS TAKING OVER.
HRRR...NARRE...ALONG WITH HOPWRF ENSEMBLE PROBABILITIES SHOW A
LARGE HOLE IN THE CLOUDS DEVELOPING THIS EVENING OVER MUCH OF MN
AND WRN WI...AND SAT IMAGES ALONG WITH OBS THE LAST HOUR CERTAINLY
POINT TO A CLEARING DEVELOPING. GIVEN THE UNCERTAINTIES IN CLOUD
COVER...TENDED TO KEEP A VFR CIG IN PLACE...THEN FOLLOWED THE
HRRR/NARRE FOR BRINGING MVFR CIGS BACK IN TO WRN SITES FROM THE
ERN DAKOTAS. OF COURSE MOS GUIDANCE BASICALLY KEEPS THE CLOUDS IN
PLACE INTO WED MORNING. CERTAINLY WOULD NOT BE SURPRISED IF MVFR
CIGS JUST FILLED BACK IN OVERNIGHT...BUT WOULD LIKE TO SEE
STRONGER CAA BEFORE GOING AS PESSIMISTIC AS MOS GUIDANCE. WHATEVER
CLOUD COVER IS OUT THERE COME WEDNESDAY...WILL LIKELY TAKE MOST
OF THE MORNING TO GET RID OF IT...BUT EVENTUALLY EXPECT RATHER
BENIGN WEATHER CONDITIONS AS SFC RIDGE MOVES OVERHEAD.
KMSP...LOW CONFIDENCE FORECAST IN TERMS OF CIGS TONIGHT. GFS/NAM
ALONG WITH THEIR MOS GUIDANCE WOULD SAY MSP KEEPS A NICE BANK OF
MVFR STRATUS OVERHEAD TONIGHT. HOWEVER...HIGH RES SHORT TERM
MODELS LIKE THE HRRR SHOW A RATHER PRONOUNCED CLEARING DEVELOPING
OVERNIGHT...WITH MSP SPENDING MUCH OF THE NIGHT WITH NOTHING MORE
THAN HIGH CLOUDS. SPLIT THE DIFFERENCE WITH THESE TAFS...AND KEPT
A BKN035 CIG THROUGH THE NIGHT...BUT WOULD NOT BE SURPRISED IF
CIGS AROUND 020 REDEVELOP LATER TONIGHT. IF CLOUDS DO
RETURN...WILL TAKE MUCH OF THE MORNING TO ERODE THEM OUT. WINDS
WILL BE MAINLY UNDER 10 KTS AND WILL REMAIN OUT OF THE N/NW
THROUGH WED AFTERNOON. WEDNESDAY EVENING WILL FEATURE A RAPID
VEERING OF THE WINDS OVER TO THE SE AS RIDGE AXIS SWINGS THROUGH.
/OUTLOOK FOR KMSP/
THU...VFR. SE WIND 10-15 KTS.
FRI...VFR. SE WIND 5 KTS.
SAT...MVFR OR LOWER WITH CHANCE OF FZRA/RA OR SN. WINDS NE 5 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
MPG/JPC/LS
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
648 PM CST TUE MAR 5 2013
.UPDATE...
ISSUED AT 640 PM CST TUE MAR 5 2013
THE GOING FORECAST LOOKS TO BE GENERALLY ON TRACK. HAVE MADE A FEW
UPDATES TO BUMP POPS UP THIS EVENING AS THE BAND OF SNOW CURRENTLY
JUST SOUTH OF THE STL METRO. OTHER THAN THAT...HAVE ADDED IN
CHANCE FOR FLURRIES EVERYWHERE FOR THE OVERNIGHT AS THE RUC KEEPS
AN ELONGATED BAND OF VORTICITY OVER THE AREA AND LITTLE POCKETS OF
FRONTOGENESIS. EXPLICIT MODELS ALSO SHOW SOME LIGHT PRECIPITATION
CONTINUING TO ROTATE AROUND THE UPPER SYSTEM AS WELL.
CARNEY
&&
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 322 PM CST TUE MAR 5 2013
WITH LITTLE IN THE WAY OF ADDITIONAL SN EXPECTED THRU
TONIGHT...WILL CANCEL THE ADVISORY SOON.
AREA OF SN MOVING INTO NWRN PORTIONS OF THE CWA JUST AHEAD OF THE
UPPER LOW. THIS SN WILL CONTINUE TO MOVE SEWD INTO THE EVENING
HOURS. AN ADDITIONAL HALF INCH...MAYBE UP TO AN INCH...CAN BE
EXPECTED. WITH CLOUDS EXPECTED TO PERSIST THRU TONIGHT...HAVE
TEMPS LOWER SLIGHTLY OVERNIGHT.
WINDS WILL CONTINUE TO BE STRONG WITH GUSTS IN THE 20 TO 30 KT
RANGE INTO THE EVE. CAN NOT RULE OUT A COUPLE OF SITES BRIEFLY
REACHING WIND ADV CRITERIA...BUT EXPECT WINDS TO STAY BELOW
CRITERIA.
&&
.LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 240 PM CST TUE MAR 5 2013
(WEDNESDAY THROUGH THURSDAY)
CYCLONIC FLOW WILL CONTINUE ACROSS THE REGION THROUGH MIDDAY
WEDNESDAY IN THE WAKE OF THE DEPARTING SYSTEM. BELIEVE THERE WILL
BE QUITE A BIT OF RESIDUAL STRATUS AT DAYBREAK...AND WHILE THIS
WILL CLEAR/DECREASE SOUTHEASTWARD DURING THE MORNING/EARLY
AFTERNOON...THERE WILL ALSO BE A TENDENCY FOR ADDITIONAL STRATOCU
TO DEVELOP WITH HEATING. WITH THIS IN MIND I HAVE SHADED MY
TEMPERATURES TOWARDS THE COOLER MET GUIDANCE. IT WILL ALSO REMAIN
BREEZY ACROSS FAR EASTERN MO INTO WESTERN ILLINOIS THROUGH THE
EARLY AFTERNOON...THEN WINDS SHOULD DIMINISH AS SURFACE HIGH
PRESSURE SETTLES INTO THE AREA. THE SURFACE HIGH/RIDGE WILL
DOMINATE THE AREA ON WEDNESDAY NIGHT LEADING TO SEASONABLY COLD
CONDITIONS. WE BEGIN THE TEMPERATURE MODERATION ON THURSDAY AS THE
SURFACE HIGH SLOWLY RETREATS TO THE EAST AND HEIGHTS ALOFT
RISE...HOWEVER HIGHS WILL STILL REMAIN BELOW AVERAGE.
(FRIDAY INTO TUESDAY)
THE WARM-UP SHOULD CONTINUE TO UNFOLD ON FRIDAY AND INTO THE
WEEKEND AS THE UPPER AIR PATTERN CONTINUES TO AMPLIFY AND THE
UPPER RIDGE BUILDS THROUGH THE MS VALLEY AND SHIFTS EASTWARD.
THERE IS BETTER AGREEMENT IN THE EVOLVING PATTERN AND HANDLING OF
THE WESTERN UPPER LOW/TROF WITH THE 12Z NWP SUITE THAN THE 00Z
GUIDANCE. THE GENERAL CONSENSUS NOW IS THE INCREASINGLY POSITIVELY
TILTED UPPER TROF WILL SHIFT INTO THE NATIONS MIDSECTION BY SUNDAY
WITH THE UPPER LOW EJECTING NEWD THROUGH THE MID MS VALLEY SUNDAY
NIGHT INTO EARLY MONDAY. THIS SHOULD BRING A GOOD RAIN THREAT TO
THE REGION LATE SATURDAY NIGHT INTO SUNDAY NIGHT. THERE ARE NOW
SOME SUGGESTIONS THAT THERE COULD BE A CHANGEOVER FROM RAIN TO
SNOW ACROSS PARTS OF NORTHERN MISSOURI LATE SUNDAY NIGHT AND
POSSIBLY POTENTIAL FOR SOME LIGHT ACCUMULATIONS...HOWEVER THE
MODELS HAVE BEEN QUITE CHAOTIC WITH THE DETAILS OF THIS SYSTEM AND
THUS CONFIDENCE IS LOW ON THIS ASPECT OF THE SYSTEM.
GLASS
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 555 PM CST TUE MAR 5 2013
ABUNDANT MVFR CIGS NOW ENTERING NRN MO AND NWRN IL IN THE WAKE OF
THE UPPER LEVEL LO THAT IS NOW MOVING THRU OUR REGION. THESE MVFR
CIGS WILL OVERSPREAD THE TAF SITES THIS EVENING AND SHOULD PERSIST
THRU MUCH OF THE DAY ON WEDNESDAY WHEN ADVENT OF SFC RIDGE SHOULD
SCATTER OUT THE CLOUDS WEDNESDAY NIGHT. SPEAKING OF THE UPPER
LEVEL SYSTEM...THIS IS THE MAIN FACTOR FOR WHY TAF SITES ARE
GETTING ANOTHER SHOT OF SNOW CURRENTLY BUT VSBYS SHOULD IMPROVE
AND SNOW SHOULD DIMINISH OVER THE NEXT FEW HOURS AS THE VAST LEVEL
OF UPPER LEVEL SUPPORT ERODES. NW GUSTY SFC WINDS WILL ALSO SLOWLY
DIMINISH BUT THEY WILL PROBABLY TAKE A GOOD PORTION OF THE NIGHT
BEFORE ACTUALLY DOING SO WITH DECENT PRESSURE RISES AND GRADIENT
PERSISTING DURING THAT TIME.
SPECIFICS FOR KSTL...PRIMARILY MVFR CIGS WILL BE PREDOMINANT FOR
THE VALID PERIOD UNTIL WEDNESDAY EVENING WHEN SFC RIDGE SHOULD
SCATTER OUT CLOUDS...VSBY DROPS FROM SNOW SHOULD GRADUALLY DAMPEN
THIS EVENING WITH ONLY FLURRIES EXPECTED AFTER 02-03Z...NW GUSTY
SFC WNDS WILL DIMINISH LATE.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1138 PM CST SUN MAR 3 2013
.UPDATE...
ISSUED AT 930 PM CST SUN MAR 3 2013
GOING FORECAST FOR A THREAT OF A LIGHT WINTRY MIX ACROSS OUR NE
COUNTIES STILL LOOKS ON THE MARK...AS REGIONAL RADAR LOOP HAS BEEN
INDICATING RELATIVELY NARROW BAND OF WAA-INDUCED PRECIP GRADUALLY
WORKING SE FROM CENTRAL IOWA. LATEST RUC AND 00Z NAM ARE STILL
SUGGESTING PTYPE WILL BE MOSTLY SNOW AT ONSET...BUT SHOULD
BECOME MIXED WITH AND TRANSITION TO SLEET AND FREEZING RAIN AS
ELEVATED WARM LAYER DEEPENS OVERNIGHT. FORTUNATELY PRECIP WILL
LIKELY BE SOMEWHAT HIT AND MISS...QUITE LIGHT... AND SHOULD ONLY
LAST AN HOUR OR SO...THEREFORE NO HEADLINES PLANNED ATTM.
ONE CHANGE TO GOING FORECAST WAS TO EXPAND THE SLIGHT CHANCE POPS
FURTHER S INTO THE STL AREA. MID LEVEL ECHO HAS BEEN EXPANDING
FROM BETWEEN IRK AND COU OVER THE LAST HOUR OR SO...AND BELIEVE
THAT SUBTLE INCREASE IN LIFT INTO THE MID MISSISSIPPI VALLEY MAY
BE JUST ENOUGH TO GET SOME PRECIP JUST S OF THE I-70 CORRIDOR.
IN THIS AREA...HAVE KEPT PTYPE AS ALL RAIN.
TRUETT
&&
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 301 PM CST SUN MAR 3 2013
FOCUS TONIGHT WILL BE PRECIP CHANCES.
STRONG WAA OVER THE REGION HAS MANAGED TO KEEP CLOUDS IN PLACE
THRU THE DAY. THIS IS ALSO RESPONSIBLE FOR THE AREA OF LIGHT SHSN OVER
ERN MO THAT HAS DEVELOPED OVER THE PAST FEW HOURS. MDLS SHOW
STRONG FORCING OVER THIS REGION THRU THIS AFTERNOON.
HOWEVER...THIS FORCING BECOMES RATHER DIFFUSE THIS EVENING...BUT
HAVE LOW SLIGHT CHANCE POPS THRU EARLY THIS EVENING TO ACCOUNT FOR
THIS. BELIEVE IT WILL MAINTAIN THE CURRENT TRACK TO THE SE AND
PROBABLY DISSIPATE BEFORE IT REACHES SERN PORTIONS OF THE CWA.
LATER TONIGHT...A SEPARATE WAA BAND MAY DEVELOP FAR ENUF TO THE SE
THAT IT WILL IMPACT NRN PORTIONS OF THE CWA. HAVE TRENDED TWD THE
GEM/ECMWF/GFS SOLNS AS THESE MDLS SEEM TO HAVE A BETTER HANDLE ON
THE CURRENT SITUATION. CONTINUE A MIX OF P-TYPES TONIGHT BASED ON
GFS PROGD SOUNDINGS AND UNCERTAINTY IN PLACEMENT OF PRECIP.
BELIEVE BULK OF PRECIP WILL BE SN UNTIL JUST BEFORE SUNRISE WHEN
MDLS WARM MID LVLS ENUF THAT IP OR FZRA WILL BE POSSIBLE.
HOWEVER...THIS IS ALSO THE TIME WHEN PRECIP IS MOST LIKELY. FOR
NOW...HAVE LIGHT ACCUMULATION OF SN/IP AS WELL AS A GLAZING OF
ICE.
&&
.LONG TERM...(MONDAY THROUGH NEXT SUNDAY)
ISSUED AT 334 PM CST SUN MAR 3 2013
(MONDAY THROUGH WEDNESDAY)
THE ONGOING NW/SE ORIENTED BAND OF PRECIPITATION DRIVEN THROUGH LOW
LEVEL WAA AND FRONTOGENTETIC FORCING SHOULD HAVE EITHER EXITED THE
CWA OR BE ON THE FAR FRINGES OF THE SOUTH CENTRAL IL COUNTIES AT
DAYBREAK ON MONDAY. MODEL SOUNDINGS OVERNIGHT TONIGHT THROUGH MONDAY
MORNING SHOW THAT STRONG LOW LEVEL WAA WILL CONTINUOUSLY ERODE THE
COLD AIR AS AN ELEVATED WARM LAYER DEVELOPS. THERMAL PROFILES AT 12Z
WITHIN THE PRECIPITATION THREAT AREA SHOW ONLY A SURFACE-BASED
SUBFREEZING COLD LAYER FROM 1-2KFT DEEP...SUGGESTIVE OF FREEZING
RAIN AND POSSIBLY SLEET AS A PTYPE. BY 15Z THE PRECIPITATION THREAT
APPEARS WELL REMOVED TO THE EAST AND THE ENTIRE LOWER TROP ACROSS
THE REGION IS WARMING. I THINK UNTIL MID-LATE AFTERNOON THERE WILL
JUST BE AN ABUNDANCE OF CLOUDS...BUT AFTER 21Z OR SO THERE COULD BE
SOME SPOTTY RAIN/SHOWERS ACROSS SE MO AND SRN IL AND ACROSS FAR NRN
MO INTO WEST CENTRAL IL. TEMPERATURES REMAIN A TOUGH CALL DUE TO THE
CLOUDS AND EXISTING SNOW COVER AND TEMPERED THEM BACK A BIT FROM
GUIDANCE OVER THE DEEPER SNOW PACK FROM CENTRAL MO THRU WEST CENTRAL
IL WHILE LETTING THEM WARM SUBSTANTIALLY ACROSS SRN MO.
THE BIGGEST ITEM OF INTEREST DURING THIS PERIOD IS THE UPPER LOW
CURRENTLY MOVING INTO THE UPPER ROCKIES. WE HAVE BEEN CAREFULLY
MONITORING THIS POTENT UPPER SYSTEM AND POTENTIAL IMPACTS MONDAY
NIGHT INTO TUESDAY AS IT MOVES THROUGH THE MID MS VALLEY. DESPITE
THE SYSTEM BEING ONSHORE NOW AND APPARENTLY WELL SAMPLED BY THE NOAM
UPPER AIR NETWORK...THERE REMAINS SIGNIFICANT DIFFERENCES WITH
RESPECT TO THE TRACK/POSITION AND EVEN TIMING OF THE UPPER
LOW...WITH POSITION DIFFERENCES ON THE ORDER OF 200 MILES BY 00Z
WED. THERE IS A GENERAL CONSENSUS THAT THE HEAVIEST SNOW BAND WILL
BE FROM NRN IA THRU NRN/CNTRL IL...HOWEVER THE EXTENT OF LIGHT TO
MODERATE SNOW FURTHER TO THE SOUTHWEST AND THRU OUR CWA IS MORE
QUESTIONABLE DUE TO THESE POSITION VARIANCES. THIS FORECAST GIVES
CREDENCE TO THE RANGE OF SOLUTIONS INCLUDING THE MORE SRN POSITIONS
OF THE UKMET AND ECMWF. STRONG CAA AND GUSTY NW WINDS IN THE WAKE
OF THE ASSOCIATED LOW LEVEL/SURFACE CYCLONES SHOULD BRING DEEPENING
COLD AIR FROM NW TO SE ACROSS THE CWA LATE MONDAY NIGHT INTO EARLY
TUESDAY SUPPORTING A CHANGE FROM RAIN TO SNOW. THE PRECIPITATION
THREAT WILL BE A RESULT OF STRONG MID/UPPER LEVEL FORCING ASSOCIATED
WITH THE MID/UPPER LOW AND VORT MAX MOVING TO ITS SOUTH. IN ADDITION
TO THE SNOWFALL WILL BE STRONG AND GUSTY NW WINDS. BY MID EVENING ON
TUESDAY THE SYSTEM AND ANY MEASURABLE SNOWFALL POTENTIAL SHOULD HAVE
EXITED TO THE EAST. CURRENTLY I HAVE SNOWFALL ACCUMULATIONS RANGING
FROM 2-3 INCHES IN NE MO AND WEST CENTRAL IL TAPERING TO JUST OVER
AN INCH THRU METRO ST LOUIS. THESE AMOUNTS WILL BE A BIT ON THE
LIGHT SIDE IF THE ECMWF AND UKMET PAN OUT. HIGH PRESSURE WILL THEN
BUILD INTO THE AREA LATE WEDNESDAY AND DOMINATE ON WED NIGHT.
(THURSDAY THROUGH SUNDAY)
BIG PATTERN CHANGE TO EVOLVE DURING THIS PERIOD WITH A TRANSITION TO
AN AMPLIFIED BUT PROGRESSIVE SPLIT FLOW REGIME. THE UPPER LOW/TROF
EXITS QUICKLY EASTWARD INTO THE ATLANTIC BY LATE THURSDAY WITH LARGE
HEIGHT RISES ALOFT IN ITS WAKE AS AN UPPER RIDGE BUILDS INTO THE MS
VALLEY AND AN UPPER LOW/TROF DIGS INTO THE WEST COAST. IN RESPONSE
WE SHOULD SEE A NICE WARM-UP IN TEMPERATURES TO ABOVE AVERAGE LEVELS
AS WE GET INTO SOUTHERLY RETURN FLOW AND H85 TEMPERATURES RISE TO +6
TO +10 DEGC BY LATE FRIDAY. THE UPPER RIDGE THEN SHIFTS INTO THE
EASTERN U.S. DURING THE WEEKEND AS THE UPPER LOW/TROF MOVES INTO THE
SWRN U.S...WHILE A THE SRN EXTENSION OF AN UPPER TROF/LOW OVER
CANADA TRANSLATES ACROSS THE UPPER MS VALLEY INTO THE NERN U.S. THIS
LATER FEATURE WILL RESULT IN AN EAST-WEST ORIENTED COLD FRONT
DIPPING DOWN INTO THE REGION AND BI-SECTING THE CWA. THE PRESENCE OF
THE FRONTAL BOUNDARY COMBINED WITH INCREASING MOISTURE AND LIFT IN
ADVANCE OF THE SWRN U.S. SYSTEM SHOULD BRING AN INCREASING THREAT OF
RAIN THRU THE WEEKEND.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1138 PM CST SUN MAR 3 2013
WAA PCPN HAS DEVELOPED OVER IOWA AND CONTINUES TO SPREAD SOUTHEAST
INTO EASTERN MO/WEST CENTRAL IL. COVERAGE WILL BE SPOTTY. FOR NOW
JUST HAVE TEMPO GROUPS AT KUIN AND METRO AREA TAFS THROUGH 10Z MONDAY.
AS FOR PCPN TYPE...KUIN IS BELOW FREEZING SO WILL SEE MOSTLY LIGHT
FREEZING RAIN...WHILE METRO AREA TO REMAIN ABOVE FREEZING WITH
JUST LIGHT RAIN. CIGS/VSBYS TO REMAIN VFR WITH THIS ACTIVITY.
OTHERWISE...SOUTHEAST WINDS TO PICKUP TO BETWEEN 10 AND 15 KTS
BEFORE BACKING TO THE EAST AND DIMINISHING JUST A BIT BY LATE THIS
AFTERNOON. WILL HAVE BETTER CHANCES OF PCPN WITH MAIN SYSTEM AFTER
00Z TUESDAY WITH IT STARTING OFF AS ALL RAIN. CIGS AND VSBYS TO
DIP DOWN TO MVFR WITH ONSET OF PCPN. PCPN TO CHANGE OVER AND/OR
MIX WITH SNOW...BUT THIS IS BEYOND CURRENT VALID TAF PERIOD.
SPECIFICS FOR KSTL...WAA PCPN HAS DEVELOPED OVER IOWA AND CONTINUES
TO SPREAD SOUTHEAST INTO EASTERN MO/WEST CENTRAL IL. COVERAGE
WILL BE SPOTTY. FOR NOW JUST HAVE TEMPO GROUP AT KSTL THROUGH 09Z MONDAY.
AS FOR PCPN TYPE...METRO AREA TO REMAIN ABOVE FREEZING WITH JUST
LIGHT RAIN. CIGS/VSBYS TO REMAIN VFR WITH THIS ACTIVITY.
OTHERWISE...SOUTHEAST WINDS TO PICKUP TO BETWEEN 10 AND 15 KTS
BEFORE BACKING TO THE EAST AND DIMINISHING JUST A BIT BY 23Z MONDAY.
WILL HAVE BETTER CHANCES OF PCPN WITH MAIN SYSTEM AFTER 03Z
TUESDAY WITH IT STARTING OFF AS ALL RAIN. CIGS AND VSBYS TO DIP
DOWN TO MVFR WITH ONSET OF PCPN. PCPN TO POSSIBLY MIX WITH
SNOW...BUT HARD TO PIN THIS DOWN...SO JUST HAVE RAIN MENTION IN
TAF.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
335 PM CST MON MAR 4 2013
.SHORT TERM...TONIGHT THROUGH THURSDAY
THE PRIMARY FORECAST CONCERNS DURING THIS PERIOD ARE PCPN AND WINDS
TONIGHT...WINDS ON TUESDAY AND POTENTIAL FOR CLOUD COVER FOR TUESDAY
NIGHT.
CLOSED LOW AT 500 MB WHICH WAS OVER EXTREME EASTERN MONTANA AT 12Z
WILL CONTINUE TO DIVE SOUTHEAST TONIGHT...REACHING THE BORDER AREA
OF SOUTH DAKOTA/MINNESOTA/IOWA BY 12Z TUESDAY AND THEN SOUTHERN
ILLINOIS BY 00Z WEDNESDAY. SURFACE ANALYSIS EARLY THIS AFTERNOON
SHOWED ONE LOW PRESSURE CENTER OVER SOUTH CENTRAL NORTH DAKOTA AND
ANOTHER OVER OKLAHOMA. AN INVERTED TROF EXTENDED NORTHWARD FROM
THE SOUTHERN LOW. NORTHERN LOW WILL PUSH SOUTHEAST AND WEAKEN
OVERNIGHT. FAIRLY TIGHT PRESSURE GRADIENT OVER THE AREA ALONG WITH
DECENT DOWNWARD MOMENTUM TRANSFER SHOULD RESULT IN GUSTY WINDS
LATER TONIGHT AND INTO TUESDAY. WILL LEAVE PREVIOUSLY ISSUED WIND
ADVISORY IN PLACE BUT EXTEND IT UNTIL 21Z. THIS CAN BE CANCELED IS
WINDS DECREASE EARLIER. ALSO ISSUED ANOTHER WIND ADVISORY SEGMENT
TO THE SOUTHEAST OF PREVIOUS ADVISORY FROM 8 AM TO 3 PM
TUESDAY...AS STRONGER WINDS OVERSPREAD MORE OF THE AREA.
RADAR ECHOES HAVE BEEN INCREASING TO OUR WEST...WITH SOME LIGHT SNOW
REPORTED IN PARTS OF SOUTHWEST NEBRASKA. RECENT HRRR AND RAP13 MODEL
RUNS INDICATE SOME PCPN WILL DEVELOP OVER ABOUT THE SOUTHEAST HALF
OF THE FORECAST AREA THIS EVENING...IN ASSOCIATION WITH 500-300 MB
Q VECTOR DIVERGENCE AND ELEVATED FRONTOGENESIS. RAP13 PCPN
AMOUNTS SEEM OVERDONE...BUT SCENARIO IS ALSO SUPPORTED BY 18Z NAM.
ON TUESDAY...FAIRLY TIGHT PRESSURE GRADIENT IS IN PLACE DURING THE
MORNING BUT THIS RELAXES IN THE AFTERNOON. THERE IS SOME SMALL
POTENTIAL FOR LIGHT SNOW TUESDAY...MAINLY FOR ABOUT THE NORTHEAST
ONE THIRD OF THE FORECAST AREA...BUT CHANCES ARE MUCH HIGHER FARTHER
TO THE EAST OF OUR AREA.
OTHERWISE...LOOK FOR MAINLY DRY CONDITIONS TUESDAY NIGHT AS HIGH
PRESSURE BUILDS IN. SOME MODELS SHOW LOW LEVEL MOISTURE MOVING INTO
THE AREA FROM THE NORTH...SO WILL HAVE TO WATCH THAT. FOR NOW...
HAVING CLEARING SKIES. THAT SURFACE RIDGE WILL PUSH OFF TO THE EAST
WEDNESDAY THROUGH THURSDAY WITH INCREASING SOUTH/SOUTHEAST WINDS...
MODERATING TEMPERATURES AND MAINLY DRY CONDITIONS.
MILLER
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
CONFIDENCE IS INCREASING THAT THE UPPER LEVEL LOW THAT WILL DIVE
INTO THE SOUTHWEST CONUS ON WED/THU WILL MOVE INTO THE PLAINS AT
SOME POINT NEXT WEEKEND. THE ECMWF/GEM HAVE REMAINED VERY CONSISTENT
OVER THE PAST COUPLE OF DAYS WHILE THE OPERATIONAL GFS HAS VARIED
WILDLY FROM THE 00Z/04 TO 12Z/O4 RUNS. THUS WILL LEAVE MUCH HEAVIER
ON THE EC/GEM/EC ENSEMBLE SOLUTIONS FOR THE TRACK OF THIS SYSTEM.
AHEAD OF THE SYSTEM/COLD FRONT WE SHOULD SEE A NICE DAY ON FRIDAY
WITH HIGHS ABOVE SEASONAL AVERAGES. THE COLD FRONT THEN MOVES
THROUGH THE FA ON THE WEEKEND WITH SLIGHTLY COOLER AIR MOVING INTO
THE REGION. THE GFS...ALTHOUGH CLOSER TO THE EC WITH THE 12Z/04
RUN...IS STILL TO FAST IN BRINGING PRECIP TO THE AREA. WILL HOLD
ONTO SOME POPS IN THE SW ON FRI NIGHT...BUT IT WILL LIKELY BE SAT OR
MAYBE EVEN SAT NIGHT BEFORE WE SEE THE BULK OF THE PRECIP ASSOCIATED
WITH THE UPPER LEVEL LOW HEAD INTO THE PLAINS.
THE EC IS VERY WARM FOR THIS SYSTEM AND WOULD HAVE LIMITED CHANCE OF
ANY FROZEN PRECIP AT ALL FOR OUR FA...AND WE WILL TREND THE FORECAST
THIS WAY. HAVE INCREASED OVERNIGHT LOWS AS WELL AS HIGHS A TOUCH FOR
MOST AREAS. REMOVED FZRA MENTION AND WENT WITH A RA/SN MIX IN THE
FAR NORTH AND OTHERWISE JUST RA OVER THE SRN 2/3RD OF THE FA. IT IS
IMPORTANT TO NOTE THAT THE FORECAST WILL HAVE CHANCES OF PRECIP FOR
SEVERAL PERIODS...BUT THIS MORE REFLECTS THE UNCERTAINTY IN THE
TIMING MORE THAN WE WILL HAVE CONTINUOUS RAIN OVER A 48 HOUR
PERIOD.
&&
.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
PERIOD OF LOW MVFR TO IFR CEILINGS IS EXPECTED AT ALL SITES
TODAY...WITH IMPROVEMENT TO VFR BY AROUND MID-AFTERNOON AT KOFK
AND EARLY EVENING AT KOMA/KLNK. KOFK IS MOST AT RISK FOR IFR
CIGS...BUT FOR NOW HAVE KEPT OUT AS CLOUD BAND IS MOVING EASTWARD
AND MOST SURROUNDING SITES ARE ABOVE 1KFT. WINDS WILL INCREASE
LATE THIS EVENING AT KOFK...AND AROUND MIDNIGHT AT KOMA/KLNK.
MODEL SOLUTIONS AGAIN POINT TO POSSIBLE LOWER CEILINGS
OVERNIGHT...BUT HAVE BEEN BURNED BY THESE THE LAST COUPLE OF DAYS
AS MODELS ARE NOT HANDLING LOW-LEVL MOISTURE WELL AND AM
SKEPTICAL. FOR NOW...HAVE PUT IN A SCT MENTION AT MVFR
LEVEL...WITH MORE CLOUD MENTION AT VFR.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 8 AM TO 3 PM CST TUESDAY FOR NEZ015-032>034-
042>045-050-051-065-066-078.
WIND ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST TUESDAY FOR
NEZ011-012-016>018-030-031.
IA...WIND ADVISORY FROM 8 AM TO 3 PM CST TUESDAY FOR IAZ043.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1115 PM CST SUN MAR 3 2013
.SYNOPSIS...
ISSUED AT 335 PM CST SUN MAR 3 2013
H5 ANALYSIS FROM THIS MORNING HAS A BROAD TROUGH OF LOW PRESSURE
OVER THE EASTERN SEA BOARD. RIDGING EXTENDED FROM THE FOUR CORNERS
NWD INTO EASTERN MT. FURTHER WEST...A STRONG SHORTWAVE TROUGH OF LOW
PRESSURE WAS TRACKING EAST INTO THE NORTHERN ROCKIES WITH 180 METER
HT FALLS NOTED AT SPOKANE WASHINGTON AND 130 METER FALLS AT GREAT
FALLS MT. AT THE SURFACE...LOW PRESSURE WAS NOTED OVER NWRN
NEBRASKA...WITH A FRONT EXTENDING SSE INTO SOUTH CENTRAL NEBRASKA. LIKE
YESTERDAY...A LARGE SPREAD IN TEMPERATURES WERE NOTED ACROSS
NEBRASKA...WITH 2 PM CST TEMPS RANGING FROM 38 AT OMAHA...TO 67
AT IMPERIAL.
&&
.UPDATE...
ISSUED AT 1013 PM CST SUN MAR 3 2013
HIGH WINDS RIPPED THROUGH RAPID CITY SD THIS PAST HOUR WITH A 66 MPH
GUST. THE HRRR SUGGESTS THE CONVECTION AND WIND GUSTS WILL WEAKEN
BEFORE THE FRONT REACHES NRN NEB AROUND 5Z-6Z.
A NEW WIND FCST IS OUT FOR MONDAY AND MONDAY NIGHT AND WINDS ARE
SLIGHTLY WEAKER...MAYBE 5 MPH.
NO DISCERNIBLE CHANGES TO THE TEMPERATURES AND RAIN/SNOW CHANCES OVERNIGHT
THROUGH MONDAY NIGHT.
UPDATE ISSUED AT 702 PM CST SUN MAR 3 2013
THE PACIFIC FRONT IS RIPPING APART NORTHEAST WY THIS EVENING WITH
A GUST TO 66 MPH AT BUFFALO. THE FRONT WILL ENTER WRN AND NCNTL
NEB TONIGHT. GUSTS SHOULD REACH 40 MPH...PERHAPS STRONGER.
A FEW COUNTIES HAVE BEEN ADDED TO THE WIND ADZY AS BLENDS OF
GEM...NAM...SREF AND MET/MAV SUGGESTED STRONGER WINDS. GIVEN THE
EVENTS THIS AFTN/EVENING ACROSS THE NRN HIGH PLAINS THIS ADDITION
SHOULD WORK. THE REST OF THE FCST IS VERY SIMILAR TO THE PREVIOUS.
RAIN AND SNOW SHOWERS ARE DEVELOPING ALONG THE PACIFIC FRONT AND
THESE SHOULD WORK THROUGH NRN NEB TONIGHT.
GIVEN THE UNCERTAINTIES OF THE FCST OVERNIGHT. THE BEST APPROACH
TO THE ONGOING HIGH WIND EVENT ACROSS THE NRN HIGH PLAINS WOULD
BE TO WATCH OBSERVATIONS CLOSELY FOR SIGNS OF WEAKENING. THE PV1.5
SFC IS EXPECTED TO REMAIN ON AN EASTERLY COURSE AFFECTING WRN SD
AND ND TONIGHT. THUS IT IS NOT SYNOPTICALLY EVIDENT THAT STRONG
OR HIGH WINDS WILL DEVELOP ACROSS WRN AND NCNTL NEBRASKA.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 335 PM CST SUN MAR 3 2013
FORECAST CONCERNS THROUGH THIS PERIOD DEAL WITH WINDS AND LIGHT
PRECIPITATION CHANCES OVER NORTHERN NEBRASKA.
THE SHORTWAVE TROUGH OVER WESTERN MONTANA WILL PUSH INTO THE DAKOTAS
THROUGH THE DAY MONDAY...BRINGING A DRAMATIC CHANGE TO THE LOCAL
WEATHER. AT THE SURFACE...THE FRONTAL BOUNDARY WILL STAY NEARLY
STATIONARY FROM CENTRAL SOUTH DAKOTA THROUGH SOUTH CENTRAL NEBRASKA
THROUGH MONDAY MORNING...BEFORE PUSHING EASTWARD BY THE END OF THE
DAY.
LOOKING AT PRECIPITATION WITH THE SYSTEM...THE BEST MOISTURE WILL
STAY UP ACROSS THE DAKOTAS WHERE THE SURFACE LOW WILL PASS. BUT WITH
THE LOCATION OF THE FRONT BEING OVER NORTH CENTRAL NEBRASKA...MAY
HAVE ENOUGH LIFT AND MOISTURE CONVERGENCE TO NEED SOME CHANCES FOR
PRECIPITATION OVER THE NORTH CENTRAL COUNTIES TONIGHT AND MONDAY
MORNING. THEN AS THE COLD FRONT MOVES THROUGH TONIGHT COULD GET A
BIT OF ENHANCED LIFT TO GIVE SOME LIGHT PRECIPITATION. WITH ONLY
LIMITED MOISTURE AND NO STRONG SIGNALS FOR GOOD PRECIPITATION
DEVELOPMENT LOCALLY...BELIEVE ANYTHING WILL BE VERY LIGHT...WITH
CHANCES FOR MEASURABLE PRECIPITATION BEING LOW. THE OTHER CONCERN IS
PRECIPITATION TYPE. THERE IS STRONG COLD AIR ADVECTION COMING BEHIND
THE FRONT TONIGHT AT 850MB...BUT AT THE SURFACE...TEMPERATURES DON/T
COOL REAL FAST. SO...WITH CURRENT TEMPERATURES IN THE 40S...50S AND
60S...WILL NEED SOME TIME TO GET THE COLDER AIR ACROSS THE AREA AND
KEPT A RAIN/SNOW MIX IN THE FORECAST THROUGH 09Z. AFTER
09Z...NORTHWEST NEBRASKA SHOULD HAVE COOLED ENOUGH FOR PRECIPITATION
TO BE SNOW...HOWEVER CLOSER TO THE FRONT OVER NORTH CENTRAL
NEBRASKA...FORECAST SOUNDINGS WERE SHOWING A SIGNAL FOR FREEZING
RAIN OR FREEZING DRIZZLE FOR A SHORT PERIOD. AS IT LOOKS LIKE THIS
WOULD OCCUR FOR A VERY SHORT PERIOD...NOT EXPECTING MUCH IF ANY ICE
ACCUMULATION...SO THREAT FOR HAZARDOUS TRAVEL SHOULD BE LOW. AFTER
12Z...TEMPERATURE PROFILES LOOK LIKE PRECIPITATION SHOULD CHANGE OVER
TO SNOW EVERYWHERE. THEN AS SURFACE TEMPERATURES WARM A BIT DURING
THE DAY...MAY AGAIN GET A CHANGEOVER TO RAIN/SNOW MIX OR RAIN.
FOR WINDS...AS THE COLD FRONT MOVES THROUGH TONIGHT...WITH HAVE
PRETTY SIGNIFICANT PRESSURE RISES SO HAVE INCREASED WINDS TONIGHT.
THE STRONGER WINDS ARE EXPECTED TO DEVELOP AROUND NOON-TIME MONDAY
ACROSS THE PANHANDLE AS THE PRESSURE GRADIENT TIGHTENS...COLD AIR
ADVECTION STRENGTHENS AND A DECENT PV ANOMALY MOVES ACROSS THE AREA.
AS THIS OCCURS...THE BOUNDARY LAYER SHOULD MIX TO AT LEAST
800MB...AND WITH UNIDIRECTIONAL WINDS GOING UPWARD...SHOULDN/T HAVE
A PROBLEM BRINGING DOWN THE STRONGER WINDS FROM ALOFT. JUST HOW
STRONG THEY WILL BE REMAINS A BIT OF A QUESTION. AS IS TYPICAL...THE
GFS AND MAV GUIDANCE IS STRONGER WITH THE WIND SPEEDS...WHILE THE
NAM AND MET GUIDANCE IS QUITE A BIT LESS. THE SIGNAL LOOKS GOOD
ENOUGH FOR AT LEAST MARGINAL WIND ADVISORY SPEEDS ACROSS THE
PANHANDLE STARTING AROUND MID-DAY...THEN TRANSITIONING ACROSS NORTH
CENTRAL NEBRASKA LATER INTO THE AFTERNOON AND EVENING. SO...HAVE
ISSUED A WIND ADVISORY FOR THOSE AREAS FOR MONDAY AFTERNOON INTO
MONDAY NIGHT.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 335 PM CST SUN MAR 3 2013
MONDAY NIGHT THROUGH WEDNESDAY...WINDS WILL BE THE MAIN
FORECAST CONCERN FROM MONDAY NIGHT INTO EARLY TUESDAY...THEN
TEMPERATURES ON TUESDAY AND WEDNESDAY AS AN ARCTIC AIRMASS PUSHES
SOUTH INTO THE CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY.
STRONG NORTHERLY WINDS WILL TRANSITION EAST FROM NORTHWESTERN
NEBRASKA MONDAY EVENING AS THE ARCTIC COLD FRONT PUSHES INTO NORTH
CENTRAL...THEN NORTHEASTERN NEBRASKA. LOW LEVEL COLD AIR ADVECTION
AND SURFACE PRESSURE RISES ARE MOST PRONOUNCED ACROSS THE N CENTRAL
CWA MONDAY EVENING WITH THE BEST WIND POTENTIAL IN THESE AREAS. GFS
BUFKIT SOUNDINGS ACROSS NORTHERN NEBRASKA...SUPPORT SUSTAINED WINDS
OF 30 TO 40 MPH...WITH GUSTS TO 50 MPH MONDAY EVENING...WHILE THE
NAM BUFKIT SOUNDINGS ARE ABOUT 5 TO 10 MPH SLOWER. WILL UTILIZE A
50/50 BLEND BETWEEN THE MAV AND MET WIND SPEEDS WHICH YIELDS WIND
SPEEDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH. DECIDED TO CARRY OVER
THE WIND ADVISORY INTO NORTH CENTRAL NEBRASKA THROUGH TUESDAY
MORNING. BY 12Z TUESDAY...LOW LEVEL COLD AIR ADVECTION WILL COME TO
AN END...WHILE THE CORE OF 30+KT 500 METER AGL WINDS...SHIFTS EAST
INTO NERN NEBRASKA. FURTHER WEST...WILL EXPIRE THE WIND ADVISORY
AROUND MIDNIGHT...AS LOW LEVEL CAA ENDS AND PRESSURE RISES END.
WINDS WILL DIMINISH FURTHER ON TUESDAY AS COLD ARCTIC HIGH PRESSURE
BUILDS INTO THE CENTRAL AND NORTHERN PLAINS. BASED ON H85
TEMPS...HIGHS TUESDAY WILL VARY WIDELY ACROSS THE FORECAST
AREA...WITH READINGS AROUND 30 IN THE NORTHEAST...TO THE LOWER 40S
IN SWRN NEBRASKA. HIGH PRESSURE WILL TRACK EAST ON TUESDAY NIGHT
WITH INCREASING SRLY WINDS FOR WEDNESDAY. WARMER TEMPERATURES WILL
BEGIN TO WORK INTO WESTERN NEBRASKA ON WEDNESDAY...HOWEVER...COLD
TEMPERATURES WILL REMAIN AT IN THE EASTERN CWA WITH HIGHS AROUND 40
FOR KONL...AND 42 FOR KANW. READINGS WILL BE IN THE LOWER 50S ACROSS
SWRN NEBRASKA AND THE EASTERN PANHANDLE. BASED ON FCST 500 METER
WINDS...SURFACE WIND SPEEDS ARE EXPECTED TO BE WELL BELOW ADVISORY
CRITERIA WEDS AFTERNOON.
WEDNESDAY NIGHT THROUGH SUNDAY...COLD AIR WILL SLIDE
EAST WITH THE HIGH WEDNESDAY NIGHT...AND SURFACE LOW PRESSURE WILL
DEEPEN OVER EASTERN COLORADO. SRLY WINDS WILL INCREASE...ALONG WITH
TEMPERATURES AS THE ARCTIC AIR MASS SHIFTS EAST OF THE AREA. FCST
H85 TEMPS WILL INCREASE TO 8 TO 12 C THURSDAY AFTERNOON AHEAD OF A
APPG COLD FRONT. THE COMBINATION OF THE APPG COLD FRONT...SRLY
WINDS...AND RIDGING ALOFT...WILL RESULT IN HIGHS IN THE 50S TO LOWER
60S THURSDAY. AFTER ONE DAY OF WARM TEMPERATURES...MUCH COOLER
TEMPERATURES AND THE POTENTIAL FOR A POTENT WINTER STORM...WILL
BEGIN TO PUSH ACROSS SRN ROCKIES ONTO THE CENTRAL AND SRN PLAINS
FRIDAY NIGHT INTO SATURDAY. SOME TRACK DIFFERENCES EXIST BETWEEN THE
GFS AND EC MODEL RUNS THIS MORNING. THE GFS REMAINS SOUTH...WITH THE
ECMWF BEING FURTHER NORTH. BOTH SOLUTIONS PUSH COLD FRONT INTO THE
FORECAST AREA EITHER FRIDAY NIGHT OR SATURDAY DEPENDING ON MODEL
CHOICE. THE RESULTANT AIRMASS BEHIND THE FRONT WILL BE A SHALLOW SUB
FREEZING LAYER...WITH DECENT MID LEVEL ASCENT NOTED ABOVE THIS
LAYER. WOULDN`T BE SURPRISED TO SEE A MIX OF PCPN ACROSS THE NORTH
FOR FRIDAY INTO FRIDAY NIGHT. HOWEVER...GIVEN THE MODEL DIFFERENCES
WITH THE TIMING OF THE FRONT...DECIDED TO WORD PRECIPITATION MENTION
AS RAIN OR SNOW ATTM. THIS WILL CARRY OVER INTO THE WEEKEND WITH
HIGHS IN THE 30S AND LOWS IN THE 20S. ATTM...THE EXTENDED BEYOND
THURSDAY REMAINS A LOW CONFIDENCE FCST...IN PARTICULAR PRECIPITATION
TYPE...AS POOR MODEL AGREEMENT IS NOTED. NO DOUBT...WE COULD SEE
SOME PRECIPITATION NEXT WEEKEND GIVEN THE CURRENT EC AND GFS
SOLNS...AND CHANCE POPS REFLECT THAT IN THE CURRENT FCST. BASED ON
EITHER SOLUTION...WE COULD BE DEALING WITH LIGHT PRECIPITATION...OR
A SIGNIFICANT SNOW STORM (12Z ECMWF SOLUTION). WILL NEED TO MONITOR
THIS CLOSELY OVER THE NEXT FEW DAYS AS WE GRAVITATE TOWARD
MIDWEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1112 PM CST SUN MAR 3 2013
A STRONG PACIFIC FRONT...CURRENTLY BETWEEN KRAP...KIEN AND KPHP WILL MOVE
THROUGH THE FCST AREA OVERNIGHT PRODUCING A BRIEF PERIOD OF STRONG WINDS
AND MVFR.
OTHERWISE VFR IS EXPECTED MONDAY AND MONDAY EVENING. WINDS WILL
INCREASE TO 32028G40KT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON CST /11 AM MST/ MONDAY TO MIDNIGHT CST
/11 PM MST/ MONDAY NIGHT FOR NEZ004-022>024-035-036-056>058-069-
094.
WIND ADVISORY FROM 3 PM MONDAY TO MIDNIGHT CST MONDAY NIGHT FOR
NEZ059-070.
WIND ADVISORY FROM 3 PM MONDAY TO 6 AM CST TUESDAY FOR
NEZ005>010-025>029-037-038.
&&
$$
UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...BROOKS
LONG TERM...CLB
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1019 PM CST SUN MAR 3 2013
.SYNOPSIS...
ISSUED AT 335 PM CST SUN MAR 3 2013
H5 ANALYSIS FROM THIS MORNING HAS A BROAD TROUGH OF LOW PRESSURE
OVER THE EASTERN SEA BOARD. RIDGING EXTENDED FROM THE FOUR CORNERS
NWD INTO EASTERN MT. FURTHER WEST...A STRONG SHORTWAVE TROUGH OF LOW
PRESSURE WAS TRACKING EAST INTO THE NORTHERN ROCKIES WITH 180 METER
HT FALLS NOTED AT SPOKANE WASHINGTON AND 130 METER FALLS AT GREAT
FALLS MT. AT THE SURFACE...LOW PRESSURE WAS NOTED OVER NWRN
NEBRASKA...WITH A FRONT EXTENDING SSE INTO SOUTH CENTRAL NEBRASKA. LIKE
YESTERDAY...A LARGE SPREAD IN TEMPERATURES WERE NOTED ACROSS
NEBRASKA...WITH 2 PM CST TEMPS RANGING FROM 38 AT OMAHA...TO 67
AT IMPERIAL.
&&
.UPDATE...
ISSUED AT 1013 PM CST SUN MAR 3 2013
HIGH WINDS RIPPED THROUGH RAPID CITY SD THIS PAST HOUR WITH A 66 MPH
GUST. THE HRRR SUGGESTS THE CONVECTION AND WIND GUSTS WILL WEAKEN
BEFORE THE FRONT REACHES NRN NEB AROUND 5Z-6Z.
A NEW WIND FCST IS OUT FOR MONDAY AND MONDAY NIGHT AND WINDS ARE
SLIGHTLY WEAKER...MAYBE 5 MPH.
NO DISCERNIBLE CHANGES TO THE TEMPERATURES AND RAIN/SNOW CHANCES OVERNIGHT
THROUGH MONDAY NIGHT.
UPDATE ISSUED AT 702 PM CST SUN MAR 3 2013
THE PACIFIC FRONT IS RIPPING APART NORTHEAST WY THIS EVENING WITH
A GUST TO 66 MPH AT BUFFALO. THE FRONT WILL ENTER WRN AND NCNTL
NEB TONIGHT. GUSTS SHOULD REACH 40 MPH...PERHAPS STRONGER.
A FEW COUNTIES HAVE BEEN ADDED TO THE WIND ADZY AS BLENDS OF
GEM...NAM...SREF AND MET/MAV SUGGESTED STRONGER WINDS. GIVEN THE
EVENTS THIS AFTN/EVENING ACROSS THE NRN HIGH PLAINS THIS ADDITION
SHOULD WORK. THE REST OF THE FCST IS VERY SIMILAR TO THE PREVIOUS.
RAIN AND SNOW SHOWERS ARE DEVELOPING ALONG THE PACIFIC FRONT AND
THESE SHOULD WORK THROUGH NRN NEB TONIGHT.
GIVEN THE UNCERTAINTIES OF THE FCST OVERNIGHT. THE BEST APPROACH
TO THE ONGOING HIGH WIND EVENT ACROSS THE NRN HIGH PLAINS WOULD
BE TO WATCH OBSERVATIONS CLOSELY FOR SIGNS OF WEAKENING. THE PV1.5
SFC IS EXPECTED TO REMAIN ON AN EASTERLY COURSE AFFECTING WRN SD
AND ND TONIGHT. THUS IT IS NOT SYNOPTICALLY EVIDENT THAT STRONG
OR HIGH WINDS WILL DEVELOP ACROSS WRN AND NCNTL NEBRASKA.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 335 PM CST SUN MAR 3 2013
FORECAST CONCERNS THROUGH THIS PERIOD DEAL WITH WINDS AND LIGHT
PRECIPITATION CHANCES OVER NORTHERN NEBRASKA.
THE SHORTWAVE TROUGH OVER WESTERN MONTANA WILL PUSH INTO THE DAKOTAS
THROUGH THE DAY MONDAY...BRINGING A DRAMATIC CHANGE TO THE LOCAL
WEATHER. AT THE SURFACE...THE FRONTAL BOUNDARY WILL STAY NEARLY
STATIONARY FROM CENTRAL SOUTH DAKOTA THROUGH SOUTH CENTRAL NEBRASKA
THROUGH MONDAY MORNING...BEFORE PUSHING EASTWARD BY THE END OF THE
DAY.
LOOKING AT PRECIPITATION WITH THE SYSTEM...THE BEST MOISTURE WILL
STAY UP ACROSS THE DAKOTAS WHERE THE SURFACE LOW WILL PASS. BUT WITH
THE LOCATION OF THE FRONT BEING OVER NORTH CENTRAL NEBRASKA...MAY
HAVE ENOUGH LIFT AND MOISTURE CONVERGENCE TO NEED SOME CHANCES FOR
PRECIPITATION OVER THE NORTH CENTRAL COUNTIES TONIGHT AND MONDAY
MORNING. THEN AS THE COLD FRONT MOVES THROUGH TONIGHT COULD GET A
BIT OF ENHANCED LIFT TO GIVE SOME LIGHT PRECIPITATION. WITH ONLY
LIMITED MOISTURE AND NO STRONG SIGNALS FOR GOOD PRECIPITATION
DEVELOPMENT LOCALLY...BELIEVE ANYTHING WILL BE VERY LIGHT...WITH
CHANCES FOR MEASURABLE PRECIPITATION BEING LOW. THE OTHER CONCERN IS
PRECIPITATION TYPE. THERE IS STRONG COLD AIR ADVECTION COMING BEHIND
THE FRONT TONIGHT AT 850MB...BUT AT THE SURFACE...TEMPERATURES DON/T
COOL REAL FAST. SO...WITH CURRENT TEMPERATURES IN THE 40S...50S AND
60S...WILL NEED SOME TIME TO GET THE COLDER AIR ACROSS THE AREA AND
KEPT A RAIN/SNOW MIX IN THE FORECAST THROUGH 09Z. AFTER
09Z...NORTHWEST NEBRASKA SHOULD HAVE COOLED ENOUGH FOR PRECIPITATION
TO BE SNOW...HOWEVER CLOSER TO THE FRONT OVER NORTH CENTRAL
NEBRASKA...FORECAST SOUNDINGS WERE SHOWING A SIGNAL FOR FREEZING
RAIN OR FREEZING DRIZZLE FOR A SHORT PERIOD. AS IT LOOKS LIKE THIS
WOULD OCCUR FOR A VERY SHORT PERIOD...NOT EXPECTING MUCH IF ANY ICE
ACCUMULATION...SO THREAT FOR HAZARDOUS TRAVEL SHOULD BE LOW. AFTER
12Z...TEMPERATURE PROFILES LOOK LIKE PRECIPITATION SHOULD CHANGE OVER
TO SNOW EVERYWHERE. THEN AS SURFACE TEMPERATURES WARM A BIT DURING
THE DAY...MAY AGAIN GET A CHANGEOVER TO RAIN/SNOW MIX OR RAIN.
FOR WINDS...AS THE COLD FRONT MOVES THROUGH TONIGHT...WITH HAVE
PRETTY SIGNIFICANT PRESSURE RISES SO HAVE INCREASED WINDS TONIGHT.
THE STRONGER WINDS ARE EXPECTED TO DEVELOP AROUND NOON-TIME MONDAY
ACROSS THE PANHANDLE AS THE PRESSURE GRADIENT TIGHTENS...COLD AIR
ADVECTION STRENGTHENS AND A DECENT PV ANOMALY MOVES ACROSS THE AREA.
AS THIS OCCURS...THE BOUNDARY LAYER SHOULD MIX TO AT LEAST
800MB...AND WITH UNIDIRECTIONAL WINDS GOING UPWARD...SHOULDN/T HAVE
A PROBLEM BRINGING DOWN THE STRONGER WINDS FROM ALOFT. JUST HOW
STRONG THEY WILL BE REMAINS A BIT OF A QUESTION. AS IS TYPICAL...THE
GFS AND MAV GUIDANCE IS STRONGER WITH THE WIND SPEEDS...WHILE THE
NAM AND MET GUIDANCE IS QUITE A BIT LESS. THE SIGNAL LOOKS GOOD
ENOUGH FOR AT LEAST MARGINAL WIND ADVISORY SPEEDS ACROSS THE
PANHANDLE STARTING AROUND MID-DAY...THEN TRANSITIONING ACROSS NORTH
CENTRAL NEBRASKA LATER INTO THE AFTERNOON AND EVENING. SO...HAVE
ISSUED A WIND ADVISORY FOR THOSE AREAS FOR MONDAY AFTERNOON INTO
MONDAY NIGHT.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 335 PM CST SUN MAR 3 2013
MONDAY NIGHT THROUGH WEDNESDAY...WINDS WILL BE THE MAIN
FORECAST CONCERN FROM MONDAY NIGHT INTO EARLY TUESDAY...THEN
TEMPERATURES ON TUESDAY AND WEDNESDAY AS AN ARCTIC AIRMASS PUSHES
SOUTH INTO THE CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY.
STRONG NORTHERLY WINDS WILL TRANSITION EAST FROM NORTHWESTERN
NEBRASKA MONDAY EVENING AS THE ARCTIC COLD FRONT PUSHES INTO NORTH
CENTRAL...THEN NORTHEASTERN NEBRASKA. LOW LEVEL COLD AIR ADVECTION
AND SURFACE PRESSURE RISES ARE MOST PRONOUNCED ACROSS THE N CENTRAL
CWA MONDAY EVENING WITH THE BEST WIND POTENTIAL IN THESE AREAS. GFS
BUFKIT SOUNDINGS ACROSS NORTHERN NEBRASKA...SUPPORT SUSTAINED WINDS
OF 30 TO 40 MPH...WITH GUSTS TO 50 MPH MONDAY EVENING...WHILE THE
NAM BUFKIT SOUNDINGS ARE ABOUT 5 TO 10 MPH SLOWER. WILL UTILIZE A
50/50 BLEND BETWEEN THE MAV AND MET WIND SPEEDS WHICH YIELDS WIND
SPEEDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH. DECIDED TO CARRY OVER
THE WIND ADVISORY INTO NORTH CENTRAL NEBRASKA THROUGH TUESDAY
MORNING. BY 12Z TUESDAY...LOW LEVEL COLD AIR ADVECTION WILL COME TO
AN END...WHILE THE CORE OF 30+KT 500 METER AGL WINDS...SHIFTS EAST
INTO NERN NEBRASKA. FURTHER WEST...WILL EXPIRE THE WIND ADVISORY
AROUND MIDNIGHT...AS LOW LEVEL CAA ENDS AND PRESSURE RISES END.
WINDS WILL DIMINISH FURTHER ON TUESDAY AS COLD ARCTIC HIGH PRESSURE
BUILDS INTO THE CENTRAL AND NORTHERN PLAINS. BASED ON H85
TEMPS...HIGHS TUESDAY WILL VARY WIDELY ACROSS THE FORECAST
AREA...WITH READINGS AROUND 30 IN THE NORTHEAST...TO THE LOWER 40S
IN SWRN NEBRASKA. HIGH PRESSURE WILL TRACK EAST ON TUESDAY NIGHT
WITH INCREASING SRLY WINDS FOR WEDNESDAY. WARMER TEMPERATURES WILL
BEGIN TO WORK INTO WESTERN NEBRASKA ON WEDNESDAY...HOWEVER...COLD
TEMPERATURES WILL REMAIN AT IN THE EASTERN CWA WITH HIGHS AROUND 40
FOR KONL...AND 42 FOR KANW. READINGS WILL BE IN THE LOWER 50S ACROSS
SWRN NEBRASKA AND THE EASTERN PANHANDLE. BASED ON FCST 500 METER
WINDS...SURFACE WIND SPEEDS ARE EXPECTED TO BE WELL BELOW ADVISORY
CRITERIA WEDS AFTERNOON.
WEDNESDAY NIGHT THROUGH SUNDAY...COLD AIR WILL SLIDE
EAST WITH THE HIGH WEDNESDAY NIGHT...AND SURFACE LOW PRESSURE WILL
DEEPEN OVER EASTERN COLORADO. SRLY WINDS WILL INCREASE...ALONG WITH
TEMPERATURES AS THE ARCTIC AIR MASS SHIFTS EAST OF THE AREA. FCST
H85 TEMPS WILL INCREASE TO 8 TO 12 C THURSDAY AFTERNOON AHEAD OF A
APPG COLD FRONT. THE COMBINATION OF THE APPG COLD FRONT...SRLY
WINDS...AND RIDGING ALOFT...WILL RESULT IN HIGHS IN THE 50S TO LOWER
60S THURSDAY. AFTER ONE DAY OF WARM TEMPERATURES...MUCH COOLER
TEMPERATURES AND THE POTENTIAL FOR A POTENT WINTER STORM...WILL
BEGIN TO PUSH ACROSS SRN ROCKIES ONTO THE CENTRAL AND SRN PLAINS
FRIDAY NIGHT INTO SATURDAY. SOME TRACK DIFFERENCES EXIST BETWEEN THE
GFS AND EC MODEL RUNS THIS MORNING. THE GFS REMAINS SOUTH...WITH THE
ECMWF BEING FURTHER NORTH. BOTH SOLUTIONS PUSH COLD FRONT INTO THE
FORECAST AREA EITHER FRIDAY NIGHT OR SATURDAY DEPENDING ON MODEL
CHOICE. THE RESULTANT AIRMASS BEHIND THE FRONT WILL BE A SHALLOW SUB
FREEZING LAYER...WITH DECENT MID LEVEL ASCENT NOTED ABOVE THIS
LAYER. WOULDN`T BE SURPRISED TO SEE A MIX OF PCPN ACROSS THE NORTH
FOR FRIDAY INTO FRIDAY NIGHT. HOWEVER...GIVEN THE MODEL DIFFERENCES
WITH THE TIMING OF THE FRONT...DECIDED TO WORD PRECIPITATION MENTION
AS RAIN OR SNOW ATTM. THIS WILL CARRY OVER INTO THE WEEKEND WITH
HIGHS IN THE 30S AND LOWS IN THE 20S. ATTM...THE EXTENDED BEYOND
THURSDAY REMAINS A LOW CONFIDENCE FCST...IN PARTICULAR PRECIPITATION
TYPE...AS POOR MODEL AGREEMENT IS NOTED. NO DOUBT...WE COULD SEE
SOME PRECIPITATION NEXT WEEKEND GIVEN THE CURRENT EC AND GFS
SOLNS...AND CHANCE POPS REFLECT THAT IN THE CURRENT FCST. BASED ON
EITHER SOLUTION...WE COULD BE DEALING WITH LIGHT PRECIPITATION...OR
A SIGNIFICANT SNOW STORM (12Z ECMWF SOLUTION). WILL NEED TO MONITOR
THIS CLOSELY OVER THE NEXT FEW DAYS AS WE GRAVITATE TOWARD
MIDWEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 524 PM CST SUN MAR 3 2013
A POWERFUL PACIFIC COLD FRONT...CURRENTLY MOVING THROUGH SERN
MT...WILL APPROACH KVTN AROUND 07Z-09Z. THE FRONT HAS THE
POTENTIAL TO PRODUCE STRONG WIND GUSTS AND MVFR AS IT SWEEPS THE FCST
AREA OVERNIGHT. THE HRRR MODEL INDICATES THE FRONT WILL HIT KVTN
AROUND 07Z AND PRODUCE WIND GUSTS OVER 50KT SO WE WILL BE
MONITORING THE FRONT AS IT MOVES THROUGH WRN SD THIS EVENING.
OTHERWISE VFR IS EXPECTED MONDAY. WINDS ARE EXPECTED TO INCREASE
T0 31028G42KT DURING THE LATE MORNING WEST...AND DURING THE AFTN
EAST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON CST /11 AM MST/ MONDAY TO MIDNIGHT CST
/11 PM MST/ MONDAY NIGHT FOR NEZ004-022>024-035-036-056>058-069-
094.
WIND ADVISORY FROM 3 PM MONDAY TO MIDNIGHT CST MONDAY NIGHT FOR
NEZ059-070.
WIND ADVISORY FROM 3 PM MONDAY TO 6 AM CST TUESDAY FOR
NEZ005>010-025>029-037-038.
&&
$$
UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...BROOKS
LONG TERM...CLB
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
932 PM EST TUE MAR 5 2013
.SYNOPSIS...
A SNOWSTORM WILL SLIDE JUST SOUTH OF OUR REGION TONIGHT AND
WEDNESDAY...WHILE JUST SPREADING CLOUDS ACROSS OUR REGION. AN UPPER
LEVEL DISTURBANCE WILL BRING THE CHANCE FOR LIGHT SNOW THURSDAY AND
FRIDAY. THEN THERE WILL BE INCREASING WARMTH FOR THE WEEKEND WITH
TEMPERATURES RISING ABOVE NORMAL.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
LOW PRESSURE ACROSS WEST VIRGINIA LATE THIS EVENING WILL CONTINUE
TO REDEVELOP AS A COASTAL LOW NEAR EASTERN VIRGINIA LATE TONIGHT.
ALL THE ACTION ASSOCIATED WITH THIS SYSTEM WILL REMAIN WELL TO OUR
SOUTH.
FOR WESTERN NEW YORK...IT WILL BE AN UNEVENTFUL NIGHT. THE MAIN
FORECAST CHALLENGE WILL ACTUALLY BE CLOUD COVER...WITH THE
11U-3.9U SATELLITE SHOWING PATCHES OF LOW CLOUDS ACROSS A FEW
SPOTS. AS OF THIS EVENING...THE MAJORITY OF WESTERN NEW YORK WAS
CLEAR. THE 00Z BUFFALO SOUNDING SHOWS AN INVERSION AT ABOUT 2000
FEET...WHICH IS LIKELY TO SHARPEN AND LOWER. THIS WILL LIKELY
CAUSE THESE LOW CLOUDS TO EXPAND A BIT...THOUGH SUBTLE DIFFERENCES
WILL DRIVE EXACTLY WHERE THE CLOUDS DEVELOP. MEANWHILE...HIGH
CLOUDS WILL SPREAD FROM SW-NE. THE GENERAL TREND WILL BE
SIMPLE...INCREASING CLOUDS.
NE WINDS HAVE ENHANCED A BIT...FLOWING DOWN ACROSS LAKE ONTARIO.
THIS WILL PROVIDE ENOUGH MIXING TO LIMIT RADIATIONAL COOLING...AND
KEEP TEMPERATURES FROM DROPPING MORE THAN A COUPLE DEGREES IN MOST
SPOTS. THE EXCEPTION WILL BE EAST OF LAKE ONTARIO...WHERE LIGHTER
WINDS AND A PERIOD OF CLEAR SKIES WILL RESULT IN RADIATIONAL
COOLING TO THE UPPER TEENS TO LOWER 20S. ELSEWHERE SHOULD ONLY
DROP INTO THE MID 20S.
THE TRACK OF THE LOW WILL LARGELY KEEP ALL PRECIPITATION JUST TO
OUR SOUTH...THOUGH WE CANNOT RULE OUT A LIGHT SNOW OR RAIN SHOWER
ON WEDNESDAY. WILL MAINTAIN CONTINUITY WITH THE SLIGHT CHANCE FOR
MEASURABLE PRECIPITATION ALONG THE SOUTHERN TIER...AND TOWARDS THE
UPPER GENESEE VALLEY AND WESTERN FINGER LAKE REGION WHERE LIMITED
LOW LEVEL CONVERGENCE WITHIN THE EASTERLY FLOW MAY PRODUCE A BRIEF
SNOW OR RAIN SHOWER.
LOWS TONIGHT WILL DROP BACK INTO THE MID 20S. IF SKIES REMAIN
CLEAR LONGER...THEN LOWS MAY DROP A FEW DEGREES BELOW THAT. HIGHS
ON WEDNESDAY WILL REBOUND BACK INTO THE MID AND UPPER 30S.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
THE MAIN STORM SYSTEM WILL BE OFF THE MID ATLANTIC WEDNESDAY NIGHT
WITH WESTERN AND CENTRAL NEW YORK LEFT IN BETWEEN THIS SYSTEM AND
THE APPROACHING NORTHERN STREAM WAVE. HOWEVER...THERE SEEMS TO BE
A MODEL CONSENSUS BRINGING SOME WRAP AROUND MOISTURE BACK INTO THE
AREA LATE WEDNESDAY NIGHT WHICH COULD BRING SOME LIGHT SNOW
WESTWARD INTO THE SOUTHERN TIER OF NEW YORK. 12Z MODEL RUN
CONTINUING TO SUGGEST THE IDEA FOR CHANCES OF PRECIPITATION WILL
INCREASE THURSDAY...AS THE NORTHERN STREAM SHORT WAVE DIVES DOWN
ACROSS THE LOWER GREAT LAKES. TEMPERATURES MAINLY IN THE MID 30S
WILL RESULT IN A MIX OF RAIN/SNOW WITH A CHANGE OVER TO ALL SNOW
BY LATE IN THE DAY.
THURSDAY NIGHT AND FRIDAY...THE QUESTION REMAINS AS TO HOW THE SHORT
WAVE ENERGY CROSSING THE LOWER LAKES WILL INTERACT WITH THE COASTAL
LOW. THERE IS SOME MODEL SUGGESTION THAT AN INTENSIFICATION OF THE
COASTAL LOW MAY ALLOW FOR A GREATER WESTWARD INFLUX OF MOISTURE INTO
EASTERN NEW YORK. THE NORTH COUNTRY MAY BE ON THE WESTERN FRINGE OF
AN AREA OF DEVELOPING HEAVY SNOWFALL ACROSS EASTERN NEW YORK.
HOWEVER...CONFIDENCE IN HOW THIS WILL PLAY OUT IS LOW AT THIS TIME
BUT DOES BEAR WATCHING.
MID/UPPER LEVEL RIDGE TO BUILD INTO THE GREAT LAKES AND OHIO VALLEY
FRIDAY NIGHT AND SATURDAY. THIS FEATURE WILL RESULT IN DRY WEATHER
CONDITIONS ALONG WITH A GENERAL WARMUP. CLOUDS WILL LIKELY LINGER
FRIDAY NIGHT...BEFORE CLOUDS DECREASE DURING THE DAY SATURDAY. MOST
AREAS SHOULD SEE HIGHS WELL INTO THE 40S SATURDAY.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE RIDGE WILL SLIDE OFF TO THE EAST EARLY IN THE PERIOD AS BOTH
THE GFS AND ECMWF SHOW A WEAK FRONTAL BOUNDARY CROSSING THE LOWER
LAKES LATE IN THE WEEKEND. TIMING OF THE FRONTAL BOUNDARY IS
HANDLED DIFFERENT BY THE TWO MODELS...AS THE MODELS HAVING
DIFFICULTY HANDLING THE SHORT WAVE ENERGY COMING OUT OF THE PLAINS
AND DAMPENING THE UPPER RIDGE. IT DOES APPEAR THAT MOISTURE WILL
BE LIMITED ENOUGH TO KEEP PRECIPITATION IN THE BROADBRUSH LOW
CHANCE CATEGORY...BUT THAT IS AS MUCH DETAIL AS CAN BE AFFORDED AT
THIS POINT. USED A CONSENSUS OF GUIDANCE FOR THIS PERIOD GIVEN THE
LIMITED CONFIDENCE IN ANY ONE MODEL.
EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE DEVELOPS EARLY NEXT WEEK
AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE PHASING OF THE
NORTHERN AND SOUTHERN STREAMS OVER THE CONUS. CONTINUED TO USE A
CONSENSUS OF GUIDANCE...BUT OVERALL CONFIDENCE IN THIS PORTION OF
THE FORECAST IS BELOW AVERAGE.
THE OVERALL TEMPERATURE PATTERN SHOULD FEATURE A GENERAL WARMER THAN
NORMAL REGIME.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
AT 00Z...SKIES WERE CLEAR ACROSS MOST OF THE AREA...EXCEPT FOR A
NARROW BAND OF MVFR CLOUDS NEAR THE SOUTH SHORES OF LAKE ONTARIO.
EXPECT THE INVERSION TO LOWER AND SHARPEN TONIGHT...WHICH WILL
LIKELY LEAD TO SOME EXPANSION OF THESE CLOUDS. GIVEN THE MARGINAL
MOISTURE...EXPECT ONLY PARTIAL COVERAGE...AND MAINLY IN THE MVFR
CATEGORY. CONFIDENCE ON TIMING AND LOCATION IS LOW. OUTSIDE OF
THIS...WINDS SHOULD KEEP THE BOUNDARY LAYER MIXED ENOUGH TO
PREVENT FOG. BASED ON THE LATEST RAP AND THE 18Z NAM...WILL CARRY
A PERIOD OF LLWS AT JHW.
THROUGH THE DAY ON WEDNESDAY A STORM SYSTEM WILL REMAIN SOUTH AND
EAST OF THE TAF SITES WITH MAINLY VFR FLIGHT CONDITIONS EXPECTED
THROUGH THE DAY.
OUTLOOK...
WEDNESDAY NIGHT...MAINLY VFR.
THURSDAY...MVFR WITH A CHANCE OF SNOW.
FRIDAY THROUGH SUNDAY...MAINLY VFR.
&&
.MARINE...
A NORTHEAST TO EASTERLY FLOW TONIGHT THROUGH TOMORROW WILL BEGIN TO
BUILD WAVES...ON BOTH THE CENTRAL ICE FREE PORTION OF LAKE ERIE AND
ALONG THE SOUTHERN SHORELINE OF LAKE ONTARIO.
BASED ON THE ENHANCED NORTHEASTERLY FLOW ON LAKE ONTARIO...HAVE
MOVED UP THE SMALL CRAFT ADVISORY ON FAR WESTERN PORTIONS OF THE
LAKE...TO BE EFFECTIVE IMMEDIATELY. THERE IS ALSO A SMALL CRAFT
ADVISORY ON LAKE ERIE SOUTH OF DUNKIRK WHERE WINDS DOWN THE LAKE
MAY PEAK TOWARDS 20 KNOTS OVERNIGHT. ELSEWHERE...EXPAND THE SMALL
CRAFT ADVISORY ON LAKE ONTARIO AS WINDS INCREASE AND BECOME MORE
NORTHERLY THROUGH WEDNESDAY.
AS THE STORM SYSTEM THAT IS TRACKING TO OUR SOUTH PUSHES TOWARDS
THE WESTERN ATLANTIC BOTH WINDS AND WAVES WILL DIMINISH ON LAKE
ERIE THROUGH THE DAY WEDNESDAY...AND LAKE ONTARIO THROUGH
WEDNESDAY NIGHT. AN UPPER LEVEL DISTURBANCE WILL TRACK ACROSS THE
REGION LATER THURSDAY AND FRIDAY...THAT WILL INCREASE WINDS AND
WAVES...POSSIBLY TO SMALL CRAFT CRITERIA ON LAKE ONTARIO.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR LEZ040.
SMALL CRAFT ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY
FOR LOZ043.
SMALL CRAFT ADVISORY FROM 7 AM TO 10 PM EST WEDNESDAY FOR
LOZ044.
SMALL CRAFT ADVISORY UNTIL 4 PM EST WEDNESDAY FOR LOZ042.
&&
$$
SYNOPSIS...THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
637 PM EST TUE MAR 5 2013
.SYNOPSIS...
A SNOWSTORM WILL SLIDE JUST SOUTH OF OUR REGION TONIGHT AND
WEDNESDAY...WHILE JUST SPREADING CLOUDS ACROSS OUR REGION. AN UPPER
LEVEL DISTURBANCE WILL BRING THE CHANCE FOR LIGHT SNOW THURSDAY AND
FRIDAY. THEN THERE WILL BE INCREASING WARMTH FOR THE WEEKEND WITH
TEMPERATURES RISING ABOVE NORMAL.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
ON THE SURFACE MAP AN AREA OF LOW PRESSURE IS CENTERED OVER
KENTUCKY. WATER VAPOR IMAGERY DISPLAYS A SHORTWAVE DROPPING FROM
SOUTH DAKOTA THROUGH IOWA AND DOWN TOWARDS MO/IL LATE THIS
AFTERNOON.
AT OF 530 PM...VISIBLE AND IR SATELLITE IMAGERY DISPLAYS LOW
STRATUS SOUTH OF LAKE ONTARIO ERODING LATE THIS AFTERNOON. THIS
HAS GIVEN WAY TO MOSTLY CLEAR SKIES ACROSS MOST OF WESTERN NEW
YORK...AT LEAST FOR THE MOMENT. UPDATE REFLECTS THE LATEST
SATELLITE TRENDS...AND NUDGED EVENING TEMPERATURES A BIT COOLER DUE
TO THE EARLY CLEARING.
EXPECT A SHARPENING INVERSION THIS EVENING WILL LIKELY LEAD TO
INCREASING LOW CLOUDS LATER TONIGHT...HOWEVER TIMING THIS IS A BIT
UNCERTAIN. EITHER WAY...HIGH AND MID LEVEL CLOUDS WILL SPREAD ACROSS
THE REGION FROM WEST TO EAST OVERNIGHT FROM THE OHIO VALLEY.
EXPECT MOST AREAS SOUTH OF LAKE ONTARIO TO BE MOSTLY CLOUDY BY
DAYBREAK...WHILE THE EASTERN LAKE ONTARIO REGION MAY HOLD ONTO A
PATCH OF CLEAR SKIES BEFORE THE UPSTREAM CLOUDINESS PUSHES IN.
THE UPSTREAM SHORTWAVE AND ITS ASSOCIATED FORCING WILL TRACK ACROSS
THE LOWER OHIO VALLEY TONIGHT AND TOWARDS THE SOUTHERN MID ATLANTIC
REGION TOMORROW. THE SURFACE LOW WILL ADVANCE TO ABOUT OHIO BEFORE A
SECONDARY SURFACE LOW FORMS TO THE LEE OF THE APPALACHIAN MOUNTAINS
AND WILL CONTINUE TO DEEPEN AS BOTH THE UPSTREAM SHORTWAVE NEARS AND
THE SYSTEM TAPS INTO THE LATENT HEAT FROM THE WARMER OCEAN WATERS.
THIS TRACK WILL LARGELY KEEP ALL PRECIPITATION JUST TO OUR
SOUTH...THOUGH WE CANNOT RULE OUT A LIGHT SNOW OR RAIN SHOWER ON
WEDNESDAY. WILL MAINTAIN CONTINUITY WITH THE SLIGHT CHANCE FOR
MEASURABLE PRECIPITATION ALONG THE SOUTHERN TIER...AND TOWARDS THE
UPPER GENESEE VALLEY AND WESTERN FINGER LAKE REGION WHERE
LIMITED LOW LEVEL CONVERGENCE WITHIN THE EASTERLY FLOW MAY PRODUCE A
BRIEF SNOW OR RAIN SHOWER.
LOWS TONIGHT WILL DROP BACK INTO THE MID 20S. IF SKIES REMAIN
CLEAR LONGER...THEN LOWS MAY DROP A FEW DEGREES BELOW THAT. HIGHS
ON WEDNESDAY WILL REBOUND BACK INTO THE MID AND UPPER 30S.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
THE MAIN STORM SYSTEM WILL BE OFF THE MID ATLANTIC WEDNESDAY NIGHT
WITH WESTERN AND CENTRAL NEW YORK LEFT IN BETWEEN THIS SYSTEM AND
THE APPROACHING NORTHERN STREAM WAVE. HOWEVER...THERE SEEMS TO BE
A MODEL CONSENSUS BRINGING SOME WRAP AROUND MOISTURE BACK INTO THE
AREA LATE WEDNESDAY NIGHT WHICH COULD BRING SOME LIGHT SNOW
WESTWARD INTO THE SOUTHERN TIER OF NEW YORK. 12Z MODEL RUN
CONTINUING TO SUGGEST THE IDEA FOR CHANCES OF PRECIPITATION WILL
INCREASE THURSDAY...AS THE NORTHERN STREAM SHORT WAVE DIVES DOWN
ACROSS THE LOWER GREAT LAKES. TEMPERATURES MAINLY IN THE MID 30S
WILL RESULT IN A MIX OF RAIN/SNOW WITH A CHANGE OVER TO ALL SNOW
BY LATE IN THE DAY.
THURSDAY NIGHT AND FRIDAY...THE QUESTION REMAINS AS TO HOW THE SHORT
WAVE ENERGY CROSSING THE LOWER LAKES WILL INTERACT WITH THE COASTAL
LOW. THERE IS SOME MODEL SUGGESTION THAT AN INTENSIFICATION OF THE
COASTAL LOW MAY ALLOW FOR A GREATER WESTWARD INFLUX OF MOISTURE INTO
EASTERN NEW YORK. THE NORTH COUNTRY MAY BE ON THE WESTERN FRINGE OF
AN AREA OF DEVELOPING HEAVY SNOWFALL ACROSS EASTERN NEW YORK.
HOWEVER...CONFIDENCE IN HOW THIS WILL PLAY OUT IS LOW AT THIS TIME
BUT DOES BEAR WATCHING.
MID/UPPER LEVEL RIDGE TO BUILD INTO THE GREAT LAKES AND OHIO VALLEY
FRIDAY NIGHT AND SATURDAY. THIS FEATURE WILL RESULT IN DRY WEATHER
CONDITIONS ALONG WITH A GENERAL WARMUP. CLOUDS WILL LIKELY LINGER
FRIDAY NIGHT...BEFORE CLOUDS DECREASE DURING THE DAY SATURDAY. MOST
AREAS SHOULD SEE HIGHS WELL INTO THE 40S SATURDAY.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE RIDGE WILL SLIDE OFF TO THE EAST EARLY IN THE PERIOD AS BOTH
THE GFS AND ECMWF SHOW A WEAK FRONTAL BOUNDARY CROSSING THE LOWER
LAKES LATE IN THE WEEKEND. TIMING OF THE FRONTAL BOUNDARY IS
HANDLED DIFFERENT BY THE TWO MODELS...AS THE MODELS HAVING
DIFFICULTY HANDLING THE SHORT WAVE ENERGY COMING OUT OF THE PLAINS
AND DAMPENING THE UPPER RIDGE. IT DOES APPEAR THAT MOISTURE WILL
BE LIMITED ENOUGH TO KEEP PRECIPITATION IN THE BROADBRUSH LOW
CHANCE CATEGORY...BUT THAT IS AS MUCH DETAIL AS CAN BE AFFORDED AT
THIS POINT. USED A CONSENSUS OF GUIDANCE FOR THIS PERIOD GIVEN THE
LIMITED CONFIDENCE IN ANY ONE MODEL.
EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE DEVELOPS EARLY NEXT WEEK
AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE PHASING OF THE
NORTHERN AND SOUTHERN STREAMS OVER THE CONUS. CONTINUED TO USE A
CONSENSUS OF GUIDANCE...BUT OVERALL CONFIDENCE IN THIS PORTION OF
THE FORECAST IS BELOW AVERAGE.
THE OVERALL TEMPERATURE PATTERN SHOULD FEATURE A GENERAL WARMER THAN
NORMAL REGIME.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AT 00Z...SKIES WERE CLEAR ACROSS MOST OF THE AREA...EXCEPT FOR A
NARROW BAND OF MVFR CLOUDS NEAR THE SOUTH SHORES OF LAKE ONTARIO.
EXPECT THE INVERSION TO LOWER AND SHARPEN TONIGHT...WHICH WILL
LIKELY LEAD TO SOME EXPANSION OF THESE CLOUDS. GIVEN THE MARGINAL
MOISTURE...EXPECT ONLY PARTIAL COVERAGE...AND MAINLY IN THE MVFR
CATEGORY. CONFIDENCE ON TIMING AND LOCATION IS LOW. OUTSIDE OF
THIS...WINDS SHOULD KEEP THE BOUNDARY LAYER MIXED ENOUGH TO
PREVENT FOG. BASED ON THE LATEST RAP AND THE 18Z NAM...WILL CARRY
A PERIOD OF LLWS AT JHW.
THROUGH THE DAY ON WEDNESDAY A STORM SYSTEM WILL REMAIN SOUTH AND
EAST OF THE TAF SITES WITH MAINLY VFR FLIGHT CONDITIONS EXPECTED
THROUGH THE DAY.
OUTLOOK...
WEDNESDAY NIGHT...MAINLY VFR.
THURSDAY...MVFR WITH A CHANCE OF SNOW.
FRIDAY THROUGH SUNDAY...MAINLY VFR.
&&
.MARINE...
A NORTHEAST TO EASTERLY FLOW TONIGHT THROUGH TOMORROW WILL BEGIN TO
BUILD WAVES...ON BOTH THE CENTRAL ICE FREE PORTION OF LAKE ERIE AND
ALONG THE SOUTHERN SHORELINE OF LAKE ONTARIO. A SMALL CRAFT ADVISORY
FOR OVERNIGHT ON LAKE ERIE SOUTH OF DUNKIRK WHERE WINDS DOWN THE
LAKE MAY PEAK TOWARDS 20 KNOTS OVERNIGHT. ON LAKE ONTARIO A SMALL
CRAFT WILL GO IN EFFECT THROUGH THE LATER OVERNIGHT HOURS. AS THE
STORM SYSTEM THAT IS TRACKING TO OUR SOUTH PUSHES TOWARDS THE
WESTERN ATLANTIC BOTH WINDS AND WAVES WILL DIMINISH ON LAKE ERIE
THROUGH THE DAY WEDNESDAY...AND LAKE ONTARIO THROUGH WEDNESDAY
NIGHT. AN UPPER LEVEL DISTURBANCE WILL TRACK ACROSS THE REGION LATER
THURSDAY AND FRIDAY...THAT WILL INCREASE WINDS AND WAVES...POSSIBLY
TO SMALL CRAFT CRITERIA ON LAKE ONTARIO.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST WEDNESDAY FOR LEZ040.
SMALL CRAFT ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY
FOR LOZ043.
SMALL CRAFT ADVISORY FROM 7 AM TO 10 PM EST WEDNESDAY FOR
LOZ044.
SMALL CRAFT ADVISORY FROM 1 AM TO 4 PM EST WEDNESDAY FOR
LOZ042.
&&
$$
SYNOPSIS...THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...APFFEL
MARINE...THOMAS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
646 PM EST TUE MAR 5 2013
.SYNOPSIS...
A POTENT STORM SYSTEM WILL CROSS THE AREA TONIGHT...BRINGING SHOWERS
AND PERHAPS A RUMBLE OF THUNDER. COLDER AIR RETURNS ALONG WITH
STRONG GUSTY WINDS WEDNESDAY INTO THURSDAY AS THIS STORM SYSTEM
LIFTS OFF TO THE NORTHEAST. THE LATE WEEK PERIOD WILL FEATURE A
RETURN OF SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 PM TUESDAY...A POWERFUL UPPER LEVEL LOW IS STILL
STRENGTHENING AS IT MOVES EAST ACROSS SOUTHERN KENTUCKY THIS EVENING
AND TOWARD NORTHERN NORTH CAROLINA WEDNESDAY MORNING. SURFACE LOW
PRESSURE CENTERED OVER SOUTHERN OHIO IS OCCLUDING AS A NEW CENTER
DEVELOPING OVER THE NC WESTERN PIEDMONT BECOMES THE DOMINANT LOW. A
COLD FRONT SOUTH OF THIS DEVELOPING LOW EXTENDS FROM NEAR MONROE NC
SOUTH THROUGH COLUMBIA AND INTO EASTERN GEORGIA.
SHOWERS AND EMBEDDED THUNDERSTORMS HAVE ACCOMPANIED THE COLD FRONT
ACROSS GEORGIA AND INTO THE CAROLINAS THIS EVENING. THERMODYNAMIC
CONDITIONS WERE MUCH MORE FAVORABLE FOR UPRIGHT CONVECTION ACROSS
GEORGIA AND THE WESTERN HALF OF SOUTH CAROLINA EARLIER. AS THE LINE
HAS MOVED INTO THE EASTERN CAROLINAS SURFACE CAPE IS ZERO...WHILE
PARCELS LIFTED FROM 875 MB CONTAIN MEAGER INSTABILITY ESTIMATED BY
THE LATEST RUC AT 100 J/KG OR LESS. BULK SHEAR THROUGH THE 0-6 KM
LAYER IS EXTREME (60-70 KT) WHICH IS PROBABLY TOO MUCH GIVEN THE
MEAGER INSTABILITY...RESULTING IN ANY UPDRAFTS GETTING DILUTED BY
THE ENVIRONMENT. WHILE I AM MAINTAINING HIGH POPS FOR MEASURABLE
PRECIP THIS EVENING...ACTUAL GAUGE-MEASURED RAINFALL AMOUNTS SHOULD
REMAIN QUITE LOW: 0.05 TO 0.15 INCHES FOR MOST AREAS.
AFTER THE FRONT SWEEPS OFFSHORE SHORTLY AFTER MIDNIGHT MUCH COLDER
AIR WILL SURGE INTO THE AREA. THE CHANGE IN AIRMASS IS VERY SUDDEN:
850 MB TEMPS SHOULD FALL FROM +7C AT 00Z TO -5C AT 12Z...
ACCOMPANIED BY SIMILAR EXTREME CHANGES IN LAYER THICKNESS VALUES AND
MID-LEVEL HEIGHTS. AS THE UPPER LOW MAKES ITS CLOSEST APPROACH TO
THE AREA WEDNESDAY AFTERNOON THE TROPOPAUSE SHOULD ACTUALLY LOWER
TO JUST ABOVE 500 MB OR ABOUT 19000 FT AGL. THIS IS WELL BELOW
TYPICAL VALUES AND SHOWS JUST HOW POWERFUL THIS SYSTEM IS. FORECAST
SOUNDINGS FROM THE RUC...NAM AND GFS SHOW DRY ADIABATIC LAPSE RATES
DEVELOPING THROUGH THE LOWEST SEVERAL THOUSAND FEET OF THE
ATMOSPHERE BY 09Z (4 AM WEDNESDAY) AS COLD ADVECTION STRENGTHENS.
WIND SPEEDS JUST 1000 FT AGL SHOULD INCREASE TO 30 KNOTS...AND TO
NEARLY 40 KNOTS AT 2000 FT AGL. THIS MOMENTUM WILL WORK ITS WAY DOWN
IN GUSTS LATE TONIGHT AND ESPECIALLY WEDNESDAY AFTER THE SUN RISES
AND LAPSE RATES ARE FORCED TO BECOME DRY ADIABATIC OVER AN EVEN
DEEPER LAYER. THE WIND ADVISORY RAISED EARLIER TODAY APPEARS TO BE
AN EXCELLENT CALL!
LOW TEMPERATURES TONIGHT SHOULD FALL TO AROUND 40 INLAND WITH MID
40S AT THE COAST...ALL WITH A DEEPLY MIXED ATMOSPHERE PREVENTING ANY
HINT OF A RADIATIONAL INVERSION.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...STRONG LOW PRESSURE SYSTEM OVER THE MID
ATLANTIC COAST EARLY WED MORNING WILL BE MOVE SLOWLY OFF THE COAST
THROUGH THE PERIOD AS STRONG HIGH PRESSURE BUILDS IN BEHIND IT. A
VERY TIGHT GRADIENT WILL EXIST BETWEEN THE TWO SYSTEMS THROUGH WED
INTO THURS WITH DEEP LAYER W-NW WINDS ADVECTING IN VERY DRY AND
COOL AIR ON BACK END OF LOW. EXPECT STRONG AND GUSTY WESTERLY
WINDS INITIALLY ON WED BECOMING NORTHWEST ON THURS. WINDS WILL BE
STRONGEST OVER COASTAL NORTH CAROLINA WHERE WINDS WILL RUN BETWEEN
20 TO 30 MPH WITH GUSTS UP TO 45 MPH. WILL ISSUE WIND ADVISORY FOR
WEDNESDAY.
COLD AND DRY ADVECTION WILL CONTINUE THROUGH WED INTO THURS ON THE
BACK END OF THE LOW. PCP WATER VALUES DROP DOWN TO LESS THAN A
QUARTER OF AN INCH AS DRY SLOT WRAPPING AROUND LOW MOVES INTO
AREA. A POTENT VORT MAX ROTATES AROUND THE LOW THROUGH WED AFTN
INTO EARLY EVENING OVER THE CAROLINAS. THIS WILL PRODUCE THE
POTENTIAL FOR CLOUDS BUT FOR NOW WILL KEEP PCP OUT OF FORECAST
WITH WESTERLY DOWNSLOPE FLOW THROUGH WED AFTN. POTENTIAL INCREASES
THROUGH WED AFTERNOON. MODELS SHOW PCP WATER VALUES REACHING UP TO
A HALF INCH REACHING INTO NORTHERN TIER COUNTIES OF CWA...BUT FOR
THE MOST PART THE BEST CHC OF ANY PCP WILL BE NORTH OF AREA.
TEMPS WILL BE SOMEWHAT CHALLENGING AS OVERNIGHT LOWS HEADING INTO
WED WILL BE ON THE WARM SIDE...UP AROUND 50 AT DAYBREAK. BUT THEN
PLENTY OF COOL AIR WILL RUSH IN FIRST FEW HOURS OF DAYBREAK.
EXPECT HIGHEST TEMP FOR WED TO OCCUR JUST AROUND MIDNIGHT AND
AFTERNOON TEMPS TO BE CLOSER TO 50. 850 TEMPS BOTTOM OUT RIGHT
AROUND NOON ON WED WITH -5C. TEMPS WILL DROP INTO THE 30S IN CAA
THROUGH WED NIGHT AND THEREFORE EXPECT TEMPS ON THE COOL SIDE
AGAIN FOR THURS. WILL UNDERCUT GUIDANCE AND KEEP WITH LOWER 50S
MOST PLACES ON THURS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...QUIET WEATHER FOR MUCH OF THE EXTENDED WITH
TEMPS WARMING TO...POTENTIALLY...WELL ABOVE NORMAL EARLY NEXT WEEK.
A COLD FRONT WILL APPROACH AT THE END OF THE PERIOD...BRINGING THE
ONLY CHANCE FOR PRECIP.
LARGE LOW PRESSURE OFF THE NEW ENGLAND COAST AND A RIDGE OF HIGH
PRESSURE BUILDING DOWN FROM THE NW WILL KEEP COOL NORTHERLY FLOW
ACROSS THE CAROLINAS FRIDAY. THE LOW PRESSURE WILL PUSH OFF TO THE
EAST BY SATURDAY AS HIGH PRESSURE RIDGES DOWN TO THE GULF COAST
THROUGH THE WKND...BECOMING CENTERED OVERHEAD SUNDAY. ALTHOUGH THIS
KEEPS LIGHT NORTH WINDS AND WEAK CAA...TEMPS WILL GRADUALLY WARM
FROM MID/UPPER 50S FRIDAY...INTO THE MID 60S SUNDAY THANKS TO THE
LIGHTER WINDS AND FULL MARCH INSOLATION. AS HIGH PUSHES OFFSHORE
MON/TUE...RETURN FLOW PUMPS MUCH WARMER AIR INTO THE REGION WITH
TEMPS RISING TO WELL ABOVE NORMAL...APPROACHING 70 BOTH
DAYS...ALTHOUGH HIGH LEVEL CLOUD COVER WILL BE ON THE INCREASE NEXT
WEEK. MINS THROUGH THE PERIOD WILL GRADUALLY INCREASE AS WELL...FROM
MID 30S FRIDAY NIGHT...TO UPPER 40S MON NIGHT.
GUIDANCE SUGGESTS A COLD FRONT WILL CROSS EARLY TUESDAY...BUT EXPECT
THIS TO BE SLOWED BY THE ANTECEDENT RIDGING AND INCREASINGLY
BOUNDARY-PARALLEL MID LEVEL FLOW. DECENT THETA-E RIDGING AHEAD OF
THIS FEATURE WILL SUPPORT SHOWERS TUESDAY...BUT BEING D7 AND
EXPECTED SLOWING OF BOUNDARY WILL CARRY ONLY SCHC/SILENT FOR NOW ON
TUE.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 00Z...GUSTY SOUTHWEST GRADIENT AHEAD OF A COLD FRONT WILL
CONTINUE THROUGH THE EVENING HOURS. LOOK FOR A NARROW BAND OF
CONVECTION TO ROLL FAIRLY RAPIDLY THROUGH THE CWA FROM 02-06Z.
CONVECTION WILL BRIEFLY BRING DOWN STRONGER WINDS THAT WILL PROBABLY
JUMP UP 08-10 KTS HIGHER THAN THE GRADIENT WINDS. ANY MVFR
CONDITIONS WILL BE FAIRLY BRIEF...MAINLY IN THE TWO HOUR WINDOW OF
THE CONVECTION. BEHIND THE FRONT...WINDS WILL SHIFT WESTERLY...WITH
MODERATE TO STRONG COLD AIR ADVECTION COMMENCING AN HOUR OR SO
LATER. ANY POST FRONTAL STRATA CU WILL BE VFR. DUE TO STRONG
MIXING...EXPECT FREQUENT GUSTS OVER 30 KTS SOMETIME AFTER
SUNRISE...CONTINUING THROUGH THE AFTERNOON HOURS.
EXTENDED OUTLOOK...EXPECT STRONG AND GUSTY WEST WINDS ON WEDNESDAY.
VFR CONDITIONS SHOULD PREVAIL THROUGH SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 PM TUESDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE
MARINE FORECAST THIS EVENING. WEATHER CONDITIONS WILL DETERIORATE
RAPIDLY AFTER MIDNIGHT AS COLDER AIR BEHIND THE FRONT PUSHES
OFFSHORE. PREVIOUS DISCUSSION FROM 630 PM FOLLOWS...
SOUTHWEST WINDS ARE STEADILY INCREASING AHEAD OF A STRONG COLD FRONT
NOW PUSHING INTO THE WESTERN CAROLINAS. THIS FRONT WILL RAPIDLY MOVE
EAST AND ACROSS THE COASTAL WATERS AFTER MIDNIGHT...ACCOMPANIED BY A
LINE OF SHOWERS AND ISOLATED THUNDERSTORMS. BEHIND THE FRONT SURFACE
PRESSURES WILL RISE RAPIDLY WHICH SHOULD RESULT IN THE ONSET OF
GALE-FORCE WINDS...AT LEAST IN GUSTS...SEVERAL HOURS BEFORE SUNRISE.
MODELS ARE IN EXCELLENT AGREEMENT WITH THE TIMING AND ANTICIPATED
HIGH IMPACT OF THIS SYSTEM TO MARINERS. NO SIGNIFICANT CHANGES HAVE
BEEN MADE TO THE FORECAST WITH THIS EARLY EVENING UPDATE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...POTENT LOW PRESSURE SYSTEM WILL BE MOVING
SLOWLY OFF THE MID ATLANTIC COAST THROUGH PERIOD. A VERY TIGHT
GRADIENT WILL EXIST BETWEEN THIS LOW AND STRONG HIGH PRESSURE
BUILDING IN ON THE BACK END. TIGHTENED GRADIENT FLOW COMBINED WITH
COLD SURGE ON BACK END OF LOW WILL PRODUCE STRONG GUSTY WESTERLY
WINDS UP TO 35 KTS WITH HIGHER GUSTS THROUGH WED. A GALE WARNING WILL
REMAIN IN EFFECT INTO WED EVENING.
MAX SEAS WILL BE WED MORNING UP AROUND 7 TO 10 FT WITH HIGHER SEAS
JUST OUTSIDE OF LOCAL WATERS. THE OFF SHORE FLOW WILL ALLOW NEAR
SHORE SEAS TO SUBSIDE BY THE END OF WED BUT STILL EXPECT 6 TO 8 FT
SEAS THROUGH WED EVENING. EXPECT A SLOW DECREASE IN SPEEDS HEADING
INTO THURSDAY AS THE LOW PRESSURE SYSTEM MOVES FURTHER OFF THE
MID ATLANTIC COAST. SEAS WILL CONTINUE TO SUBSIDE IN SLOWLY
WEAKENING OFF SHORE FLOW. EXPECT SEAS DOWN BELOW SCA BY DAYBREAK
THURSDAY WITH HEIGHTS AROUND 4 TO 5 FT IN OUTER WATERS AND LESS
THAN 3 FT NEAR SHORE. BY THURSDAY EVENING EXPECT SEAS 2-4 FEET
ACROSS THE WATERS.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...VERY LARGE LOW PRESSURE MOVING SLOWLY OFF THE
NEW ENGLAND COAST WILL KEEP A PINCHED GRADIENT WITH WINDS VEERING
FROM NW TO NORTH THROUGH FRIDAY. WINDS WILL BE 15-20 KTS...WITH
GUSTS UP TO 30 KTS DURING THE DAY. ALTHOUGH THIS IS PRIMARILY AN
OFFSHORE DIRECTION...SEAS WILL REMAIN ELEVATED AT 2-5 FT.
HOWEVER...AS WINDS BECOME SLIGHTLY MORE NORTHERLY LATE FRIDAY...WAVE
HEIGHTS NEAR THE 20NM BOUNDARY OF AMZ250 AND AMZ252 MAY APPROACH
6FT...AND A SHORT SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY NIGHT
THROUGH SATURDAY MORNING. SEAS THROUGH SATURDAY WILL BE FORMED VIA A
COMBINATION OF NORTHERLY WIND WAVES...AND AN EASTERLY BACK SWELL OF
2-4 FT AT 13 SEC.
HIGH PRESSURE BUILDS DOWN ACROSS THE AREA FROM THE NW SAT/SUN
CAUSING WINDS TO SHIFT SLOWLY FROM NORTH TO SE BY LATE SUNDAY...WITH
SPEEDS DECREASING TO LESS THAN 10 KTS DUE TO THE RELAXED GRADIENT.
SEAS RESPOND ONLY SLOWLY WITH A 2-4 FT EASTERLY BACKSWELL PERSISTING
WITHIN THE SPECTRUM. STILL...SEAS WILL FALL THROUGH THE
WKND...BECOMING 2-4 FT ON SUNDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...WIND ADVISORY FROM 3 AM TO 6 PM EST WEDNESDAY FOR SCZ017-023-
024-032-033-039-053>056.
NC...WIND ADVISORY FROM 3 AM TO 6 PM EST WEDNESDAY FOR NCZ087-096-
099-105>110.
MARINE...GALE WARNING UNTIL 6 PM EST WEDNESDAY FOR
AMZ250-252-254-256.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
946 PM EST TUE MAR 5 2013
.SYNOPSIS...
A POTENT STORM SYSTEM WILL CROSS THE AREA TONIGHT...BRINGING SHOWERS
AND PERHAPS A RUMBLE OF THUNDER. COLDER AIR RETURNS ALONG WITH
STRONG GUSTY WINDS WEDNESDAY INTO THURSDAY AS THIS STORM SYSTEM
LIFTS OFF TO THE NORTHEAST. THE LATE WEEK PERIOD WILL FEATURE A
RETURN OF SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 PM TUESDAY...A POWERFUL UPPER LEVEL LOW IS STILL
STRENGTHENING AS IT MOVES EAST ACROSS SOUTHERN KENTUCKY THIS EVENING
AND TOWARD NORTHERN NORTH CAROLINA WEDNESDAY MORNING. SURFACE LOW
PRESSURE CENTERED OVER SOUTHERN OHIO IS OCCLUDING AS A NEW CENTER
DEVELOPING OVER THE NC WESTERN PIEDMONT BECOMES THE DOMINANT LOW. A
COLD FRONT SOUTH OF THIS DEVELOPING LOW EXTENDS FROM NEAR MONROE NC
SOUTH THROUGH COLUMBIA AND INTO EASTERN GEORGIA.
SHOWERS AND EMBEDDED THUNDERSTORMS HAVE ACCOMPANIED THE COLD FRONT
ACROSS GEORGIA AND INTO THE CAROLINAS THIS EVENING. THERMODYNAMIC
CONDITIONS WERE MUCH MORE FAVORABLE FOR UPRIGHT CONVECTION ACROSS
GEORGIA AND THE WESTERN HALF OF SOUTH CAROLINA EARLIER. AS THE LINE
HAS MOVED INTO THE EASTERN CAROLINAS SURFACE CAPE IS ZERO...WHILE
PARCELS LIFTED FROM 875 MB CONTAIN MEAGER INSTABILITY ESTIMATED BY
THE LATEST RUC AT 100 J/KG OR LESS. BULK SHEAR THROUGH THE 0-6 KM
LAYER IS EXTREME (60-70 KT) WHICH IS PROBABLY TOO MUCH GIVEN THE
MEAGER INSTABILITY...RESULTING IN ANY UPDRAFTS GETTING DILUTED BY
THE ENVIRONMENT. WHILE I AM MAINTAINING HIGH POPS FOR MEASURABLE
PRECIP THIS EVENING...ACTUAL GAUGE-MEASURED RAINFALL AMOUNTS SHOULD
REMAIN QUITE LOW: 0.05 TO 0.15 INCHES FOR MOST AREAS.
AFTER THE FRONT SWEEPS OFFSHORE SHORTLY AFTER MIDNIGHT MUCH COLDER
AIR WILL SURGE INTO THE AREA. THE CHANGE IN AIRMASS IS VERY SUDDEN:
850 MB TEMPS SHOULD FALL FROM +7C AT 00Z TO -5C AT 12Z...
ACCOMPANIED BY SIMILAR EXTREME CHANGES IN LAYER THICKNESS VALUES AND
MID-LEVEL HEIGHTS. AS THE UPPER LOW MAKES ITS CLOSEST APPROACH TO
THE AREA WEDNESDAY AFTERNOON THE TROPOPAUSE SHOULD ACTUALLY LOWER
TO JUST ABOVE 500 MB OR ABOUT 19000 FT AGL. THIS IS WELL BELOW
TYPICAL VALUES AND SHOWS JUST HOW POWERFUL THIS SYSTEM IS. FORECAST
SOUNDINGS FROM THE RUC...NAM AND GFS SHOW DRY ADIABATIC LAPSE RATES
DEVELOPING THROUGH THE LOWEST SEVERAL THOUSAND FEET OF THE
ATMOSPHERE BY 09Z (4 AM WEDNESDAY) AS COLD ADVECTION STRENGTHENS.
WIND SPEEDS JUST 1000 FT AGL SHOULD INCREASE TO 30 KNOTS...AND TO
NEARLY 40 KNOTS AT 2000 FT AGL. THIS MOMENTUM WILL WORK ITS WAY DOWN
IN GUSTS LATE TONIGHT AND ESPECIALLY WEDNESDAY AFTER THE SUN RISES
AND LAPSE RATES ARE FORCED TO BECOME DRY ADIABATIC OVER AN EVEN
DEEPER LAYER. THE WIND ADVISORY RAISED EARLIER TODAY APPEARS TO BE
AN EXCELLENT CALL!
LOW TEMPERATURES TONIGHT SHOULD FALL TO AROUND 40 INLAND WITH MID
40S AT THE COAST...ALL WITH A DEEPLY MIXED ATMOSPHERE PREVENTING ANY
HINT OF A RADIATIONAL INVERSION.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...STRONG LOW PRESSURE SYSTEM OVER THE MID
ATLANTIC COAST EARLY WED MORNING WILL BE MOVE SLOWLY OFF THE COAST
THROUGH THE PERIOD AS STRONG HIGH PRESSURE BUILDS IN BEHIND IT. A
VERY TIGHT GRADIENT WILL EXIST BETWEEN THE TWO SYSTEMS THROUGH WED
INTO THURS WITH DEEP LAYER W-NW WINDS ADVECTING IN VERY DRY AND
COOL AIR ON BACK END OF LOW. EXPECT STRONG AND GUSTY WESTERLY
WINDS INITIALLY ON WED BECOMING NORTHWEST ON THURS. WINDS WILL BE
STRONGEST OVER COASTAL NORTH CAROLINA WHERE WINDS WILL RUN BETWEEN
20 TO 30 MPH WITH GUSTS UP TO 45 MPH. WILL ISSUE WIND ADVISORY FOR
WEDNESDAY.
COLD AND DRY ADVECTION WILL CONTINUE THROUGH WED INTO THURS ON THE
BACK END OF THE LOW. PCP WATER VALUES DROP DOWN TO LESS THAN A
QUARTER OF AN INCH AS DRY SLOT WRAPPING AROUND LOW MOVES INTO
AREA. A POTENT VORT MAX ROTATES AROUND THE LOW THROUGH WED AFTN
INTO EARLY EVENING OVER THE CAROLINAS. THIS WILL PRODUCE THE
POTENTIAL FOR CLOUDS BUT FOR NOW WILL KEEP PCP OUT OF FORECAST
WITH WESTERLY DOWNSLOPE FLOW THROUGH WED AFTN. POTENTIAL INCREASES
THROUGH WED AFTERNOON. MODELS SHOW PCP WATER VALUES REACHING UP TO
A HALF INCH REACHING INTO NORTHERN TIER COUNTIES OF CWA...BUT FOR
THE MOST PART THE BEST CHC OF ANY PCP WILL BE NORTH OF AREA.
TEMPS WILL BE SOMEWHAT CHALLENGING AS OVERNIGHT LOWS HEADING INTO
WED WILL BE ON THE WARM SIDE...UP AROUND 50 AT DAYBREAK. BUT THEN
PLENTY OF COOL AIR WILL RUSH IN FIRST FEW HOURS OF DAYBREAK.
EXPECT HIGHEST TEMP FOR WED TO OCCUR JUST AROUND MIDNIGHT AND
AFTERNOON TEMPS TO BE CLOSER TO 50. 850 TEMPS BOTTOM OUT RIGHT
AROUND NOON ON WED WITH -5C. TEMPS WILL DROP INTO THE 30S IN CAA
THROUGH WED NIGHT AND THEREFORE EXPECT TEMPS ON THE COOL SIDE
AGAIN FOR THURS. WILL UNDERCUT GUIDANCE AND KEEP WITH LOWER 50S
MOST PLACES ON THURS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...QUIET WEATHER FOR MUCH OF THE EXTENDED WITH
TEMPS WARMING TO...POTENTIALLY...WELL ABOVE NORMAL EARLY NEXT WEEK.
A COLD FRONT WILL APPROACH AT THE END OF THE PERIOD...BRINGING THE
ONLY CHANCE FOR PRECIP.
LARGE LOW PRESSURE OFF THE NEW ENGLAND COAST AND A RIDGE OF HIGH
PRESSURE BUILDING DOWN FROM THE NW WILL KEEP COOL NORTHERLY FLOW
ACROSS THE CAROLINAS FRIDAY. THE LOW PRESSURE WILL PUSH OFF TO THE
EAST BY SATURDAY AS HIGH PRESSURE RIDGES DOWN TO THE GULF COAST
THROUGH THE WKND...BECOMING CENTERED OVERHEAD SUNDAY. ALTHOUGH THIS
KEEPS LIGHT NORTH WINDS AND WEAK CAA...TEMPS WILL GRADUALLY WARM
FROM MID/UPPER 50S FRIDAY...INTO THE MID 60S SUNDAY THANKS TO THE
LIGHTER WINDS AND FULL MARCH INSOLATION. AS HIGH PUSHES OFFSHORE
MON/TUE...RETURN FLOW PUMPS MUCH WARMER AIR INTO THE REGION WITH
TEMPS RISING TO WELL ABOVE NORMAL...APPROACHING 70 BOTH
DAYS...ALTHOUGH HIGH LEVEL CLOUD COVER WILL BE ON THE INCREASE NEXT
WEEK. MINS THROUGH THE PERIOD WILL GRADUALLY INCREASE AS WELL...FROM
MID 30S FRIDAY NIGHT...TO UPPER 40S MON NIGHT.
GUIDANCE SUGGESTS A COLD FRONT WILL CROSS EARLY TUESDAY...BUT EXPECT
THIS TO BE SLOWED BY THE ANTECEDENT RIDGING AND INCREASINGLY
BOUNDARY-PARALLEL MID LEVEL FLOW. DECENT THETA-E RIDGING AHEAD OF
THIS FEATURE WILL SUPPORT SHOWERS TUESDAY...BUT BEING D7 AND
EXPECTED SLOWING OF BOUNDARY WILL CARRY ONLY SCHC/SILENT FOR NOW ON
TUE.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 00Z...GUSTY SOUTHWEST GRADIENT AHEAD OF A COLD FRONT WILL
CONTINUE THROUGH THE EVENING HOURS. LOOK FOR A NARROW BAND OF
CONVECTION TO ROLL FAIRLY RAPIDLY THROUGH THE CWA FROM 02-06Z.
CONVECTION WILL BRIEFLY BRING DOWN STRONGER WINDS THAT WILL PROBABLY
JUMP UP 08-10 KTS HIGHER THAN THE GRADIENT WINDS. ANY MVFR
CONDITIONS WILL BE FAIRLY BRIEF...MAINLY IN THE TWO HOUR WINDOW OF
THE CONVECTION. BEHIND THE FRONT...WINDS WILL SHIFT WESTERLY...WITH
MODERATE TO STRONG COLD AIR ADVECTION COMMENCING AN HOUR OR SO
LATER. ANY POST FRONTAL STRATA CU WILL BE VFR. DUE TO STRONG
MIXING...EXPECT FREQUENT GUSTS OVER 30 KTS SOMETIME AFTER
SUNRISE...CONTINUING THROUGH THE AFTERNOON HOURS.
EXTENDED OUTLOOK...EXPECT STRONG AND GUSTY WEST WINDS ON WEDNESDAY.
VFR CONDITIONS SHOULD PREVAIL THROUGH SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 PM TUESDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE
MARINE FORECAST THIS EVENING. WEATHER CONDITIONS WILL DETERIORATE
RAPIDLY AFTER MIDNIGHT AS COLDER AIR BEHIND THE FRONT PUSHES
OFFSHORE. PREVIOUS DISCUSSION FROM 630 PM FOLLOWS...
SOUTHWEST WINDS ARE STEADILY INCREASING AHEAD OF A STRONG COLD FRONT
NOW PUSHING INTO THE WESTERN CAROLINAS. THIS FRONT WILL RAPIDLY MOVE
EAST AND ACROSS THE COASTAL WATERS AFTER MIDNIGHT...ACCOMPANIED BY A
LINE OF SHOWERS AND ISOLATED THUNDERSTORMS. BEHIND THE FRONT SURFACE
PRESSURES WILL RISE RAPIDLY WHICH SHOULD RESULT IN THE ONSET OF
GALE-FORCE WINDS...AT LEAST IN GUSTS...SEVERAL HOURS BEFORE SUNRISE.
MODELS ARE IN EXCELLENT AGREEMENT WITH THE TIMING AND ANTICIPATED
HIGH IMPACT OF THIS SYSTEM TO MARINERS. NO SIGNIFICANT CHANGES HAVE
BEEN MADE TO THE FORECAST WITH THIS EARLY EVENING UPDATE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...POTENT LOW PRESSURE SYSTEM WILL BE MOVING
SLOWLY OFF THE MID ATLANTIC COAST THROUGH PERIOD. A VERY TIGHT
GRADIENT WILL EXIST BETWEEN THIS LOW AND STRONG HIGH PRESSURE
BUILDING IN ON THE BACK END. TIGHTENED GRADIENT FLOW COMBINED WITH
COLD SURGE ON BACK END OF LOW WILL PRODUCE STRONG GUSTY WESTERLY
WINDS UP TO 35 KTS WITH HIGHER GUSTS THROUGH WED. A GALE WARNING WILL
REMAIN IN EFFECT INTO WED EVENING.
MAX SEAS WILL BE WED MORNING UP AROUND 7 TO 10 FT WITH HIGHER SEAS
JUST OUTSIDE OF LOCAL WATERS. THE OFF SHORE FLOW WILL ALLOW NEAR
SHORE SEAS TO SUBSIDE BY THE END OF WED BUT STILL EXPECT 6 TO 8 FT
SEAS THROUGH WED EVENING. EXPECT A SLOW DECREASE IN SPEEDS HEADING
INTO THURSDAY AS THE LOW PRESSURE SYSTEM MOVES FURTHER OFF THE
MID ATLANTIC COAST. SEAS WILL CONTINUE TO SUBSIDE IN SLOWLY
WEAKENING OFF SHORE FLOW. EXPECT SEAS DOWN BELOW SCA BY DAYBREAK
THURSDAY WITH HEIGHTS AROUND 4 TO 5 FT IN OUTER WATERS AND LESS
THAN 3 FT NEAR SHORE. BY THURSDAY EVENING EXPECT SEAS 2-4 FEET
ACROSS THE WATERS.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...VERY LARGE LOW PRESSURE MOVING SLOWLY OFF THE
NEW ENGLAND COAST WILL KEEP A PINCHED GRADIENT WITH WINDS VEERING
FROM NW TO NORTH THROUGH FRIDAY. WINDS WILL BE 15-20 KTS...WITH
GUSTS UP TO 30 KTS DURING THE DAY. ALTHOUGH THIS IS PRIMARILY AN
OFFSHORE DIRECTION...SEAS WILL REMAIN ELEVATED AT 2-5 FT.
HOWEVER...AS WINDS BECOME SLIGHTLY MORE NORTHERLY LATE FRIDAY...WAVE
HEIGHTS NEAR THE 20NM BOUNDARY OF AMZ250 AND AMZ252 MAY APPROACH
6FT...AND A SHORT SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY NIGHT
THROUGH SATURDAY MORNING. SEAS THROUGH SATURDAY WILL BE FORMED VIA A
COMBINATION OF NORTHERLY WIND WAVES...AND AN EASTERLY BACK SWELL OF
2-4 FT AT 13 SEC.
HIGH PRESSURE BUILDS DOWN ACROSS THE AREA FROM THE NW SAT/SUN
CAUSING WINDS TO SHIFT SLOWLY FROM NORTH TO SE BY LATE SUNDAY...WITH
SPEEDS DECREASING TO LESS THAN 10 KTS DUE TO THE RELAXED GRADIENT.
SEAS RESPOND ONLY SLOWLY WITH A 2-4 FT EASTERLY BACKSWELL PERSISTING
WITHIN THE SPECTRUM. STILL...SEAS WILL FALL THROUGH THE
WKND...BECOMING 2-4 FT ON SUNDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...WIND ADVISORY FROM 3 AM TO 6 PM EST WEDNESDAY FOR SCZ017-023-
024-032-033-039-053>056.
NC...WIND ADVISORY FROM 3 AM TO 6 PM EST WEDNESDAY FOR NCZ087-096-
099-105>110.
MARINE...GALE WARNING UNTIL 6 PM EST WEDNESDAY FOR
AMZ250-252-254-256.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...43
AREA FORECAST DISCUSSION
NWS RALEIGH NC
228 PM EST MON MAR 4 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BRIEFLY BUILD OVER THE CAROLINAS TODAY.
A STRONG LOW PRESSURE SYSTEM WILL AFFECT THE CAROLINAS AND SOUTHERN
VIRGINIA TUESDAY AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM MONDAY...
LITTLE CHANGE TO THE FORECAST FOR TODAY. NC LIES BETWEEN A SURFACE
LOW OVER MAINE AND WEAK HIGH PRESSURE OVER THE EASTERN GOMEX.
CLEAR SKIES WILL CONTINUE EAST OF THE MOUNTAINS WITH PW NEAR 0.10"
IN THE WAKE OF A VORT MAX EXITING THE NC COAST. RAP SOUNDINGS
SUGGEST WIND GUSTS TO AROUND 20MPH THIS MORNING SHOULD WEAKEN AFTER
18Z...SO HAVE ADJUSTED GUSTS DOWNWARD THIS AFTERNOON. GUIDANCE IS
IN GOOD AGREEMENT ON HIGHS OF 49-52 NORTH TO SOUTH. -SMITH
TONIGHT...MID LEVEL S/W RIDGE AND ATTENDANT SURFACE RIDGE WILL SCOOT
ACROSS THE FORECAST AREA. THE APPROACH OF A STRONG UPPER LEVEL LOW
DROPPING SEWD FROM THE UPPER MIDWEST WILL INCREASE/THICKEN CLOUD
COVER BY LATE EVENING-OVERNIGHT HOURS. GFS SPITS PUT A FEW
HUNDREDTHS IN THE NW PIEDMONT BY MORNING. THIS LOOKS OVERDONE
CONSIDERING THE DEGREE OF DRY AIR BELOW THE CLOUD BASE AND WEAK OR
NON-EXISTENT ISENTROPIC LIFT THROUGH 12Z TUE. FAVOR MIN TEMPS
LOW-MID 30S IN THE WEST AND FAR SOUTH WHERE CLOUDS EXPECTED TO BE
THICKER SOONER...TO AROUND 30 IN THE FAR EAST-NE WHERE THINNER CLOUD
COVER EXPECTED UNTIL MIDNIGHT OR SO.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 225 PM MONDAY...
INTERESTING MULTI-THREAT WEATHER SYSTEM FOR MIDWEEK... WITH CONCERNS
ABOUT POSSIBLE STRONG/SEVERE WEATHER AS WELL AS SNOW AND WIND.
FOR TUESDAY: THE MID-UPPER VORTEX OVER NW IA TUESDAY MORNING WILL
DROP QUICKLY THROUGH SRN IL BY EARLY TUESDAY EVENING... CAUSING
RAPID SURFACE LOW DEEPENING JUST TO ITS ESE OVER KY. WITH THE POLAR
850 MB WARM FRONT EXPECTED TO HAVE SHIFTED TO OUR NORTHEAST BY
TUESDAY MORNING... MOIST ISENTROPIC UPGLIDE BEGINS IN EARNEST AFTER
12Z TUESDAY THROUGH THE 285K-300K LAYER ACCOMPANYING THE SECONDARY
850 MB WARM FRONT THAT WILL SURGE TO THE NNE THROUGH CENTRAL NC
TUESDAY... REACHING THE VA BORDER BY NIGHTFALL. THE GFS IS AS MUCH
AS 6 HRS FASTER THAN THE NAM BRINGING PRECIP THROUGH CENTRAL NC...
AND THIS FASTER SOLUTION HAS SOME SUPPORT FROM THE ECMWF AND SREF
MEAN AND IS PREFERRED. EXPECT OVERCAST SKIES SOON AFTER SUNRISE WITH
CLOUD BASES LOWERING AS THE LOW LEVEL MOISTURE TRANSPORT IN THE WARM
SECTOR STRENGTHENS. THE GFS DEPICTS A WEAK WEDGE REGIME AT ONSET AS
THE PRECIP ATTEMPTS TO LOCK IN THE SURFACE-BASED STABLE POOL IN THE
PIEDMONT... BUT THE RELATIVE WEAKNESS AND UNFAVORABLE LOCATION OF
THE PRECEDING SURFACE HIGH FAVORS ALLOWING THE WARM SECTOR TO
OVERTAKE THIS AIR MASS... THUS THE NOTABLY STABLE AIR SHOULD LINGER
OVER ONLY THE FAR NORTHERN PIEDMONT THROUGH TUESDAY. EXPECT VERY
LITTLE RAIN CONFINED TO THE FAR NORTH AND NW CWA IN THE MORNING...
THEN COVERAGE SHOULD INCREASE TO LIKELY ALONG AND NW OF THE I-85
CORRIDOR AS THE COLUMN MOISTENS FURTHER WITH STRENGTHENING MOIST
UPGLIDE. WITH WEAKER UPGLIDE AND A DEEPER DRY SUBCLOUD LAYER TO THE
SOUTH AND EAST OF RALEIGH... ANY RAIN HERE SHOULD BE LIGHTER WITH
MUCH LOWER COVERAGE. EXPECT HIGHS FROM 50 NEAR THE VA BORDER TO 64
IN THE FAR SOUTH AND SOUTHEAST CWA WITH THINNER CLOUDS AND BETTER
HEATING.
FOR TUESDAY NIGHT: THE INTENSE MID LEVEL VORTEX MOVES TO THE NRN
PIEDMONT BY 12Z WEDNESDAY... WHILE AT THE SURFACE... THE PRIMARY LOW
SHIFTS FROM ERN KY TOWARD SRN OH WITH A TRIPLE POINT LOW FORMING
OVER THE WRN PIEDMONT/SRN FOOTHILLS TUESDAY EVENING THEN MOVING TO
FAR SE VA BY DAWN WEDNESDAY. MODELS INDICATE A BAND OF SHOWERS AND
POSSIBLE STORMS JUST AHEAD OF THE COLD FRONT... FUELED BY STRONG
DEEP ASCENT GENERATED BY VIGOROUS UPPER DIVERGENCE (WITH THE 120+ KT
JET OVER THE SOUTHEAST STATES)... DCVA... AND INCOMING MASSIVE
HEIGHT FALLS OVER 260 METERS. WHILE THE OVERALL INSTABILITY IS
PROJECTED TO BE QUITE WEAK (UNDER 100 J/KG MLCAPE)... THE STRENGTH
OF THE DYNAMIC FORCING AND THE ANTICIPATED MID LEVEL DRY PUNCH AND
ITS POSSIBLE IMPACT ON INSTABILITY (ESPECIALLY WITH CONTINUED
WARM/MOIST NEAR-SURFACE AIR) WARRANTS INCLUSION OF THUNDER...
PRIMARILY BETWEEN 23Z AND 06Z... AFTER WHICH TIME THE SURFACE FRONT
SHOULD HAVE MOVED TO COASTAL NC AND BEYOND. WE DO HAVE SOME CONCERN
THAT WE COULD SEE A SURGE OF ENHANCED WINDS RIGHT BEHIND THE FRONT
DURING THE OVERNIGHT HOURS GIVEN THE POTENTIAL FOR INJECTION OF
STRATOSPHERIC AIR INTO THE TROPOSPHERE AS THE DYNAMIC TROPOPAUSE
DROPS TO BELOW 700 MB FROM 06Z-12Z. SO EVEN WITHOUT A LOT OF
INSTABILITY... GIVEN THE TREMENDOUS 60-80 KTS OF DEEP LAYER SHEAR
AND STEEPENING LAPSE RATES TO OVER 6.5 C/KM... WE MAY STILL SEE A
FEW STRONG AND POSSIBLY DAMAGING WIND GUSTS. THE RISK OF TORNADIC
ACTIVITY SHOULD BE FAIRLY LOW WITH THE WARM FRONT HAVING RETREATED
NORTH OF THE BORDER... HOWEVER WE WILL NEED TO KEEP A CLOSE EYE ON
ANY CONVECTION NEAR THE VORTICITY-RICH TRACK OF THE TRIPLE-POINT
LOW. BOTTOM LINE: WILL SWEEP CATEGORICAL POPS ACROSS CENTRAL NC
PRIMARILY DURING THE EVENING... SHOWERS WITH ISOLATED STORMS...
FOLLOWED BY A LOWER CHANCE OF SHALLOW RAIN SHOWERS TRENDING TO A
BRIEF RAIN/SNOW MIX OVERNIGHT (MAINLY OVER THE FAR NORTHERN CWA)
ACCOMPANYING THE 925-850 MB FRONT... AND A PERIOD OF STRONGER WINDS.
THE LIKELY SCARCITY OF MOISTURE ABOVE -12C OVERNIGHT AND MARGINAL TO
UNFAVORABLE SURFACE TEMPS SHOULD LIMIT THE THREAT OF ANY
ACCUMULATING FROZEN PRECIP TUESDAY NIGHT. LOWS 33 WEST TO 43 EAST.
FOR WEDNESDAY: ATTENTION THEN SHIFTS TO THE POTENTIAL FOR BANDED
SNOW AS THE SURFACE LOW MOVES FROM SE VA EARLY TO THE ENE TO OFF
DELMARVA BY LATE IN THE DAY. BASED ON THE PROJECTED TRACK OF THE
850-700 MB LOW AND FRONTOGENESIS... THE MOST INTENSE BANDED SNOWFALL
SHOULD HOLD OVER WRN/CENTRAL VA INTO MD/DC/SE PA... ALTHOUGH THE
TAIL END OF SUCH A BAND COULD CERTAINLY BRUSH ACROSS THE VA/NC
BORDER COUNTIES TO AREAS NORTH AND NE OF ROCKY MOUNT. MID LEVEL
LAPSE RATES OVER 6.0 C/KM WRAP AROUND INTO NORTH CENTRAL NC (AS DOES
A 50-60 KT LOW LEVEL JET)... THUS THERE THE POTENTIAL EXISTS FOR
UPRIGHT CONVECTION FROM OUR FAR NORTHERN COUNTIES TO THE
NORTH/NORTHEAST. THE GFS SUGGESTS THAT MOISTURE AND ASCENT ONLY
BRIEFLY REACH INTO THE -12C TO -18C LAYER OVER THE NORTHERN AND NE
CWA WEDNESDAY... PLUS THE NEAR-SURFACE AIR IS EXPECTED TO WARM WELL
ABOVE FREEZING... SO ANY OPPORTUNITY FOR APPRECIABLE SNOW IN OUR
AREA SHOULD BE FAIRLY QUICK AND AREALLY LIMITED. THE UNFAVORABLE
TIME OF DAY IS ALSO A MITIGATING FACTOR WITH AT LEAST SOME DAYTIME
HEATING TAKING PLACE. THAT SAID... ANY SHIFT IN THE FORECAST TRACK
OF THE SURFACE AND MID LEVEL LOW COULD BRING THE COLDER AIR AND MORE
FOCUSED SNOW BANDING SOUTHWARD INTO CENTRAL NC... SO VIGILANCE IS
CERTAINLY WARRANTED HERE. WILL HOLD ONTO GOOD CHANCE TO LIKELY POPS
MAINLY NORTH AND NE OF RALEIGH... KEEPING IT A RAIN/SNOW MIX AS
PARTIAL THICKNESSES HOVER AROUND THE MOSTLY-SNOW/INDETERMINATE
PORTION OF THE CLIMO-BASED NOMOGRAM. THE TEMP FORECAST IS A TOUGH
ONE... AS LOW LEVEL THICKNESSES SHOULD BE COOL (ABOUT 20 METERS
ABOVE NORMAL) BUT NOT REMARKABLY SO... AND THE LOWEST 5000 FT OR SO
SHOULD BECOME WELL-MIXED THROUGH THE DAY WITH A NNWRLY DOWNSLOPE
COMPONENT ESPECIALLY AFFECTING THE WRN AND SRN CWA. HAVE ADJUSTED
HIGHS UPWARD A BIT TO RANGE FROM 43 FAR NORTH TO 54 SOUTH. THE
STRENGTHENING MSLP GRADIENT AND AFOREMENTIONED LOW LEVEL JET WILL
YIELD WINDY CONDITIONS... WITH NW WINDS SUSTAINED AT 15-25 MPH
LIKELY GUSTING OVER 35 MPH... NOT FAR FROM WIND ADVISORY CRITERIA.
FOR WEDNESDAY NIGHT: EXPECT GRADUALLY CLEARING SKIES AND DECREASING
WINDS (BUT STILL RATHER BREEZY) AS THE COASTAL STORM MOVES OUT OVER
THE ATLANTIC... AND THE COLUMN OVER CENTRAL NC DRIES AND STABILIZES.
WITH THE NEAR-SURFACE AIR REMAINING STIRRED OVERNIGHT... EXPECT LOWS
AROUND 30-35 DESPITE THE COOLER AIR MASS BUILDING IN FROM THE WEST.
-GIH
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 230 AM MONDAY...
THE DEEP LOW PRESSURE SYSTEM (WHICH IS EXPECTED TO MOVE ACROSS THE
REGION TUESDAY INTO WEDNESDAY) WILL SHIFT SLOWLY OFF TO THE EAST OF
THE AREA LATE WEEK... WHILE SURFACE HIGH PRESSURE BUILDS INTO THE
AREA AND HEIGHTS ALOFT RISE. SUBSIDENCE BEHIND THE EXITING SYSTEM
WILL PROVIDE THE AREA WITH SUNNY TO MOSTLY SUNNY SKIES FOR LATE
WEEK. HOWEVER... GIVEN THE NORTHERLY/NORTHWESTERLY FLOW... WITH AT
TIME BREEZE SURFACE WINDS ON THURSDAY... EXPECT TEMPS WILL REMAIN
BELOW NORMAL THROUGH AT LEAST THURSDAY AND FRIDAY. THUS... WILL GO
WITH HIGHS RANGING FROM GENERALLY THE UPPER 40S TO MID 50S THURSDAY
TO THE MID TO UPPER 50S FRIDAY. LOWS DURING THIS TIME AREA EXPECTED
TO BE IN THE UPPER 20S TO LOWER 30S (FRIDAY AND SATURDAY MORNINGS).
THE SURFACE RIDGE AXIS IS EXPECTED TO SHIFT TO THE EAST OF THE AREA
ON SATURDAY... YIELDING WARMING CONDITIONS... WITH THE NEXT
SIGNIFICANT SYSTEM EXPECTED TO REMAIN TO THE WEST OF THE AREA
THROUGH THE END OF THE FORECAST PERIOD. THUS... WILL CONTINUE DRY
CONDITIONS... WITH WARMING TEMPS. HOWEVER... EXPECTED CLOUD COVER TO
INCREASE DURING THE LATTER HALF OF THE WEEKEND AS THE NEXT SYSTEM
APPROACHES... ALONG WITH POSSIBLY SOME MID AND HIGH LEVEL CLOUD
COVER ASSOCIATED WITH A PASSING NORTHERN STREAM SYSTEM. THIS YIELDS
EXPECTED HIGH TEMPS NEAR NORMAL ON SATURDAY TO LOWER TO MID 60S
SUNDAY... WITH LOW TEMPS SUNDAY MORNING IN THE UPPER 30S TO AROUND
40.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 100 PM MONDAY...
VFR CONDITIONS OBSERVED ACROSS CENTRAL NC. NORTHWESTERLY WIND GUSTS
HAVE RELAXED A BIT AND BECOME MORE SPORADIC. THIS TREND WILL
CONTINUE THIS AFTERNOON...BECOMING LESS THAN 5KT AND WESTERLY THIS
EVENING. A LOW PRESSURE SYSTEM DIPPING OUT OF THE UPPER MIDWEST
WILL APPROACH FROM THE WEST-NORTHWEST ON TUESDAY...CROSSING CENTRAL
NC TUESDAY EVENING/NIGHT. WHILE THE MAIN SHIELD OF PRECIPITATION
ASSOCIATED WITH THE LOW WONT ARRIVE UNTIL AFTER THE TAF PERIOD...A
FEW SHOWERS MAY BE POSSIBLE AT KGSO/KINT BY 18Z. HOWEVER... BASED
ON LOW CONFIDENCE IN THE EXACT TIMING OF INITIAL PRECIP...HAVE
CHOSEN NOT TO INCLUDE ANY MVFR CEILINGS IN THE CURRENT TAF.
OUTLOOK...
A AREA OF LOW PRESSURE WILL CROSSING CENTRAL NC TUESDAY
EVENING/NIGHT. SHOWERS...AND POSSIBLY A FEW ISOLATED
THUNDERSTORMS...WILL IMPACT THE AREA BETWEEN ROUGHLY 21Z TUESDAY AND
09Z WEDNESDAY. SOME IMPROVEMENT OF CONDITIONS WILL BE POSSIBLE
WEDNESDAY MORNING BEFORE ANOTHER ROUND OF RAIN/SNOW FILLS BACK IN
ACROSS THE NORTHEASTERN HALF OF NC WEDNESDAY AFTERNOON. THIS SHOULD
MOSTLY IMPACT POINTS FROM KRDU TO KRWI AND NORTHWARD. WINDS
INITIALLY OUT OF THE SOUTH TUESDAY NIGHT WILL SWING AROUND TO
WESTERLY ON WEDNESDAY...POTENTIALLY GUSTING TO AROUND 30MPH
WEDNESDAY AFTERNOON.
VFR CONDITIONS ARE EXPECTED TO RETURN BY THURSDAY AND LAST INTO THE
WEEKEND.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/SMITH
SHORT TERM...HARTFIELD
LONG TERM...BSD
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
100 PM EST MON MAR 4 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BRIEFLY BUILD OVER THE CAROLINAS TODAY.
A STRONG LOW PRESSURE SYSTEM WILL AFFECT THE CAROLINAS AND SOUTHERN
VIRGINIA TUESDAY AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM MONDAY...
LITTLE CHANGE TO THE FORECAST FOR TODAY. NC LIES BETWEEN A SURFACE
LOW OVER MAINE AND WEAK HIGH PRESSURE OVER THE EASTERN GOMEX.
CLEAR SKIES WILL CONTINUE EAST OF THE MOUNTAINS WITH PW NEAR 0.10"
IN THE WAKE OF A VORT MAX EXITING THE NC COAST. RAP SOUNDINGS
SUGGEST WIND GUSTS TO AROUND 20MPH THIS MORNING SHOULD WEAKEN AFTER
18Z...SO HAVE ADJUSTED GUSTS DOWNWARD THIS AFTERNOON. GUIDANCE IS
IN GOOD AGREEMENT ON HIGHS OF 49-52 NORTH TO SOUTH. -SMITH
TONIGHT...MID LEVEL S/W RIDGE AND ATTENDANT SURFACE RIDGE WILL SCOOT
ACROSS THE FORECAST AREA. THE APPROACH OF A STRONG UPPER LEVEL LOW
DROPPING SEWD FROM THE UPPER MIDWEST WILL INCREASE/THICKEN CLOUD
COVER BY LATE EVENING-OVERNIGHT HOURS. GFS SPITS PUT A FEW
HUNDREDTHS IN THE NW PIEDMONT BY MORNING. THIS LOOKS OVERDONE
CONSIDERING THE DEGREE OF DRY AIR BELOW THE CLOUD BASE AND WEAK OR
NON-EXISTENT ISENTROPIC LIFT THROUGH 12Z TUE. FAVOR MIN TEMPS
LOW-MID 30S IN THE WEST AND FAR SOUTH WHERE CLOUDS EXPECTED TO BE
THICKER SOONER...TO AROUND 30 IN THE FAR EAST-NE WHERE THINNER CLOUD
COVER EXPECTED UNTIL MIDNIGHT OR SO.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 420 AM MONDAY...
QUICK UPDATE BELOW TO WEDNESDAY PERIOD FOR WINDS.
TUESDAY AND TUESDAY NIGHT...
THE APPROACH OF A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL CAUSE
WEATHER CONDITIONS TO DETERIORATE ACROSS CENTRAL NC TUESDAY. THE
APPROACH OF THIS SYSTEM WILL ENHANCE THE 850MB SLY FLOW BY MID DAY
AND CONTINUE THROUGH THE AFTERNOON HOURS. RAIN INITIALLY FALLING
THROUGH THE DRY SUB-CLOUD LAYER WILL LEAD TO EVAPORATIVE COOLING AND
AN IN-SITU CAD EVENT ACROSS THE FAR NORTHERN PIEDMONT. THIS CAD
SHOULD BE QUITE SHALLOW AND MAY BE EASILY SCOURED OUT BY
STRENGTHENING LOW LEVEL SLY FLOW. DO NOT EXPECT MAX TEMPS FOR THE
DAYLIGHT HOURS TO OCCUR ACROSS THE FAR NORTHERN COUNTIES UNTIL CLOSE
TO SUNSET. MOS GUIDANCE APPEARS TOO WARM CONSIDERING THE POTENTIAL
FOR THE IN-SITU CAD...BUT DID ADJUST MAX TEMPS UP 3-5 DEGREES FROM
PREVIOUS FORECAST.
NEAR TERM MODEL GUIDANCE IN GENERAL AGREEMENT ON THE PLACEMENT OF
850MB WARM FRONT ACROSS THE NORTHERN PIEDMONT INTO THE NORTHERN
COASTAL PLAIN LATE TUESDAY AFTERNOON-TUESDAY EVENING. EXPECT AXIS
OF MODERATE RAIN TO SET-UP ALONG THIS FEATURE. FARTHER
SOUTH...EXPECT PRECIP TO BE MORE SHOWERY IN NATURE. MID LEVEL LAPSE
RATES STILL INCREASE TO AROUND 7 DEG C/KM BY 00Z WED. THUS THE IDEA
OF ELEVATED CONVECTION LATE TUESDAY INTO TUESDAY EVENING STILL
APPEARS PROBABLE...ESPECIALLY TUESDAY EVENING WHEN MID LEVEL TROUGH
AND SFC LOW TRAVERSES THE REGION. WHILE KINEMATICS SUPPORTIVE OF THE
POTENTIAL FOR STRONG CONVECTION...LACK OF SURFACE BASED INSTABILITY
WILL LIMIT SEVERE WEATHER ATTRIBUTES WITH THE CONVECTION AT THIS
TIME.
WILL MAINTAIN FORECAST CONTINUITY OF GREATER PRECIP CHANCES TUESDAY
AFTERNOON AND TUESDAY NIGHT WITH LIKELY TO CATEGORICAL POPS DURING
THIS PERIOD. DID GO WITH A SLIGHTLY SLOWER PRECIP ARRIVAL
TUESDAY MORNING. AS SYSTEM BEGINS TO DEPART THE REGION TOWARD
DAYBREAK WEDNESDAY...SHARPLY COLDER AIR ALOFT WILL BRING A THREAT OF
RAIN MIXED WITH SNOW TO THE NW PIEDMONT. -WSS
WEDNESDAY AND WEDNESDAY NIGHT:
MODELS ARE COMING INTO BETTER AGREEMENT ON WEDNESDAY... SHOWING THE
SURFACE LOW INVOF THE NC/VA BORDER NEAR THE COASTAL REGION BY 12Z
WEDNESDAY... WITH THE 500 MB LOW QUICKLY MOVING ACROSS OUR AREA AND
INTO THE SAME GENERALLY AREA BY 18Z WEDNESDAY. THE GFS/NAM/ECMWF
HAVE TRENDED A BIT DRIER ACROSS THE AREA ON WEDNESDAY (WITH LITTLE
IF ANY PRECIP ACROSS THE SOUTHWEST NOW AFTER 12Z)... WITH THE SLIGHT
JOG TO THE NORTH WITH THE TRACK OF THE LOW... ALLOWING MORE OF A
DRYING NW TO NORTHERLY FLOW IN THE WAKE OF THE PASSING MID LEVEL
LOW. HOWEVER... IT STILL APPEAR LIKELY THAT WE WILL SEE SOME PRECIP
FILL BACK IN ACROSS THE NORTHEASTERN HALF OF THE CWA WITH STEEPENING
LAPSE RATES AND A POSSIBLE DEFORMATION BAND EXTENDING ACROSS OUR
NORTH/NORTHEAST (WITH THE MORE SIGNIFICANT PRECIP TO THE
NORTH/NORTHEAST OF OUR AREA). THE GFS BEGINS TO SHOW SIGNS OF THE
SYSTEM LIFTING OFF/MEANDERING MORE NORTH/NORTHEASTWARD WEDNESDAY
AFTERNOON/NIGHT. FOR THIS REASON HAVE ELECTED TO GO WITH MORE OF A
BLEND OF THE NAM/ECMWF FOR POPS/QPF LATE WEDNESDAY MORNING THROUGH
WEDNESDAY NIGHT... AS WE THINK THE BLOCKING HIGH ALOFT ACROSS SE
CANADA SHOULD HELP PREVENT A MORE NORTH/NORTHEASTWARD TRACK (WHICH
THE GFS HAS). THUS... WITH LOW LEVEL THICKNESS CRASHING AND
SUPPORTIVE OF ALL SNOW ACROSS THE NORTHEASTERN HALF (WHERE PRECIP IS
EXPECTED AND SATURATION RETURNING INTO THE -10 TO -20 LAYER C) OF
CENTRAL NC WE MAY SEE SOME ACCUMULATING SNOW (POSSIBLY AT FIRST
MIXED WITH RAIN... DEPENDING ON TEMPS IN THE BOUNDARY LAYER AND
LOCATIONS OF THE DEFORMATION BAND ALONG WITH SATURATION ALOFT)...
ESPECIALLY ACROSS THE FAR NORTHEASTERN PIEDMONT AND NORTHERN COASTAL
PLAIN. GIVEN WE ARE STILL TALKING ABOUT THE MAIN TIME FRAME FOR
ACCUMULATING SNOWFALL BEING WEDNESDAY MID/LATE MORNING INTO THE
AFTERNOON/EARLY EVENING WE WILL NOT ISSUE A WINTER STORM WATCH AT
THIS TIME. HOWEVER... IF FORECAST MODELS CONTINUE TO INDICATE THE
DEFORMATION BAND PIVOTING THROUGH OUR NORTH/NORTHEASTERN COUNTIES
THEN A WINTER STORM WATCH MAYBE NEEDED IN FUTURE FORECAST WITH THE
POTENTIAL FOR SOME DECENT ACCUMULATIONS NORTH OF A LINE FROM ROXBORO
TO LOUISBURG TO ROCKY MOUNT. IN ADDITION TO THE THREAT OF SNOW...
WNW TO NW WINDS WILL STRENGTHEN AS AS THE SYSTEM DEEPENS AND BECOMES
MORE VERTICALLY STACKED ON WEDNESDAY. THUS... THINK WE COULD SEE
WINDS IN THE 20 TO 25 MPH RANGE SUSTAINED... WITH GUSTS AS HIGH AS
30 TO 35 MPH WEDNESDAY... WHICH COULD CREATE LOW VISBYS IN AREAS OF
SNOW. HIGH TEMPS WILL BE QUITE DIFFICULT... WITH THE PRECIP ACROSS
THE NORTHEAST... WITH SKIES EVEN BEGIN TO CLEAR OUT A BIT ACROSS THE
FAR SOUTHWEST LATE IN THE DAY. THIS WILL YIELD A NON-DIURNAL TREND.
THIS YIELDS HIGH TEMPS RANGING FROM THE MID TO UPPER 30S
NORTH/NORTHEAST TO MID TO UPPER 40S SOUTH/WEST. SKIES WILL BEGIN TO
SLOWLY CLEAR FROM SOUTHWEST TO NORTHEAST ON THURSDAY MORNING... WITH
POSSIBLY THE TREAT OF SOME BLACK ICE. EXPECT LOW TEMPS TO RANGE FROM
THE LOWER TO MID 30S. -BSD
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 230 AM MONDAY...
THE DEEP LOW PRESSURE SYSTEM (WHICH IS EXPECTED TO MOVE ACROSS THE
REGION TUESDAY INTO WEDNESDAY) WILL SHIFT SLOWLY OFF TO THE EAST OF
THE AREA LATE WEEK... WHILE SURFACE HIGH PRESSURE BUILDS INTO THE
AREA AND HEIGHTS ALOFT RISE. SUBSIDENCE BEHIND THE EXITING SYSTEM
WILL PROVIDE THE AREA WITH SUNNY TO MOSTLY SUNNY SKIES FOR LATE
WEEK. HOWEVER... GIVEN THE NORTHERLY/NORTHWESTERLY FLOW... WITH AT
TIME BREEZE SURFACE WINDS ON THURSDAY... EXPECT TEMPS WILL REMAIN
BELOW NORMAL THROUGH AT LEAST THURSDAY AND FRIDAY. THUS... WILL GO
WITH HIGHS RANGING FROM GENERALLY THE UPPER 40S TO MID 50S THURSDAY
TO THE MID TO UPPER 50S FRIDAY. LOWS DURING THIS TIME AREA EXPECTED
TO BE IN THE UPPER 20S TO LOWER 30S (FRIDAY AND SATURDAY MORNINGS).
THE SURFACE RIDGE AXIS IS EXPECTED TO SHIFT TO THE EAST OF THE AREA
ON SATURDAY... YIELDING WARMING CONDITIONS... WITH THE NEXT
SIGNIFICANT SYSTEM EXPECTED TO REMAIN TO THE WEST OF THE AREA
THROUGH THE END OF THE FORECAST PERIOD. THUS... WILL CONTINUE DRY
CONDITIONS... WITH WARMING TEMPS. HOWEVER... EXPECTED CLOUD COVER TO
INCREASE DURING THE LATTER HALF OF THE WEEKEND AS THE NEXT SYSTEM
APPROACHES... ALONG WITH POSSIBLY SOME MID AND HIGH LEVEL CLOUD
COVER ASSOCIATED WITH A PASSING NORTHERN STREAM SYSTEM. THIS YIELDS
EXPECTED HIGH TEMPS NEAR NORMAL ON SATURDAY TO LOWER TO MID 60S
SUNDAY... WITH LOW TEMPS SUNDAY MORNING IN THE UPPER 30S TO AROUND
40.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 100 PM MONDAY...
VFR CONDITIONS OBSERVED ACROSS CENTRAL NC. NORTHWESTERLY WIND GUSTS
HAVE RELAXED A BIT AND BECOME MORE SPORADIC. THIS TREND WILL
CONTINUE THIS AFTERNOON...BECOMING LESS THAN 5KT AND WESTERLY THIS
EVENING. A LOW PRESSURE SYSTEM DIPPING OUT OF THE UPPER MIDWEST
WILL APPROACH FROM THE WEST-NORTHWEST ON TUESDAY...CROSSING CENTRAL
NC TUESDAY EVENING/NIGHT. WHILE THE MAIN SHIELD OF PRECIPITATION
ASSOCIATED WITH THE LOW WONT ARRIVE UNTIL AFTER THE TAF PERIOD...A
FEW SHOWERS MAY BE POSSIBLE AT KGSO/KINT BY 18Z. HOWEVER... BASED
ON LOW CONFIDENCE IN THE EXACT TIMING OF INITIAL PRECIP...HAVE
CHOSEN NOT TO INCLUDE ANY MVFR CEILINGS IN THE CURRENT TAF.
OUTLOOK...
A AREA OF LOW PRESSURE WILL CROSSING CENTRAL NC TUESDAY
EVENING/NIGHT. SHOWERS...AND POSSIBLY A FEW ISOLATED
THUNDERSTORMS...WILL IMPACT THE AREA BETWEEN ROUGHLY 21Z TUESDAY AND
09Z WEDNESDAY. SOME IMPROVEMENT OF CONDITIONS WILL BE POSSIBLE
WEDNESDAY MORNING BEFORE ANOTHER ROUND OF RAIN/SNOW FILLS BACK IN
ACROSS THE NORTHEASTERN HALF OF NC WEDNESDAY AFTERNOON. THIS SHOULD
MOSTLY IMPACT POINTS FROM KRDU TO KRWI AND NORTHWARD. WINDS
INITIALLY OUT OF THE SOUTH TUESDAY NIGHT WILL SWING AROUND TO
WESTERLY ON WEDNESDAY...POTENTIALLY GUSTING TO AROUND 30MPH
WEDNESDAY AFTERNOON.
VFR CONDITIONS ARE EXPECTED TO RETURN BY THURSDAY AND LAST INTO THE
WEEKEND.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/SMITH
SHORT TERM...WSS/BSD
LONG TERM...BSD
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
930 AM EST MON MAR 4 2013
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BRIEFLY BUILD OVER THE CAROLINAS TODAY.
A STRONG LOW PRESSURE SYSTEM WILL AFFECT THE CAROLINAS AND SOUTHERN
VIRGINIA TUESDAY AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM MONDAY...
LITTLE CHANGE TO THE FORECAST FOR TODAY. NC LIES BETWEEN A SURFACE
LOW OVER MAINE AND WEAK HIGH PRESSURE OVER THE EASTERN GOMEX.
CLEAR SKIES WILL CONTINUE EAST OF THE MOUNTAINS WITH PW NEAR 0.10"
IN THE WAKE OF A VORT MAX EXITING THE NC COAST. RAP SOUNDINGS
SUGGEST WIND GUSTS TO AROUND 20MPH THIS MORNING SHOULD WEAKEN AFTER
18Z...SO HAVE ADJUSTED GUSTS DOWNWARD THIS AFTERNOON. GUIDANCE IS
IN GOOD AGREEMENT ON HIGHS OF 49-52 NORTH TO SOUTH. -SMITH
TONIGHT...MID LEVEL S/W RIDGE AND ATTENDANT SURFACE RIDGE WILL SCOOT
ACROSS THE FORECAST AREA. THE APPROACH OF A STRONG UPPER LEVEL LOW
DROPPING SEWD FROM THE UPPER MIDWEST WILL INCREASE/THICKEN CLOUD
COVER BY LATE EVENING-OVERNIGHT HOURS. GFS SPITS PUT A FEW
HUNDREDTHS IN THE NW PIEDMONT BY MORNING. THIS LOOKS OVERDONE
CONSIDERING THE DEGREE OF DRY AIR BELOW THE CLOUD BASE AND WEAK OR
NON-EXISTENT ISENTROPIC LIFT THROUGH 12Z TUE. FAVOR MIN TEMPS
LOW-MID 30S IN THE WEST AND FAR SOUTH WHERE CLOUDS EXPECTED TO BE
THICKER SOONER...TO AROUND 30 IN THE FAR EAST-NE WHERE THINNER CLOUD
COVER EXPECTED UNTIL MIDNIGHT OR SO.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 420 AM MONDAY...
QUICK UPDATE BELOW TO WEDNESDAY PERIOD FOR WINDS.
TUESDAY AND TUESDAY NIGHT...
THE APPROACH OF A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL CAUSE
WEATHER CONDITIONS TO DETERIORATE ACROSS CENTRAL NC TUESDAY. THE
APPROACH OF THIS SYSTEM WILL ENHANCE THE 850MB SLY FLOW BY MID DAY
AND CONTINUE THROUGH THE AFTERNOON HOURS. RAIN INITIALLY FALLING
THROUGH THE DRY SUB-CLOUD LAYER WILL LEAD TO EVAPORATIVE COOLING AND
AN IN-SITU CAD EVENT ACROSS THE FAR NORTHERN PIEDMONT. THIS CAD
SHOULD BE QUITE SHALLOW AND MAY BE EASILY SCOURED OUT BY
STRENGTHENING LOW LEVEL SLY FLOW. DO NOT EXPECT MAX TEMPS FOR THE
DAYLIGHT HOURS TO OCCUR ACROSS THE FAR NORTHERN COUNTIES UNTIL CLOSE
TO SUNSET. MOS GUIDANCE APPEARS TOO WARM CONSIDERING THE POTENTIAL
FOR THE IN-SITU CAD...BUT DID ADJUST MAX TEMPS UP 3-5 DEGREES FROM
PREVIOUS FORECAST.
NEAR TERM MODEL GUIDANCE IN GENERAL AGREEMENT ON THE PLACEMENT OF
850MB WARM FRONT ACROSS THE NORTHERN PIEDMONT INTO THE NORTHERN
COASTAL PLAIN LATE TUESDAY AFTERNOON-TUESDAY EVENING. EXPECT AXIS
OF MODERATE RAIN TO SET-UP ALONG THIS FEATURE. FARTHER
SOUTH...EXPECT PRECIP TO BE MORE SHOWERY IN NATURE. MID LEVEL LAPSE
RATES STILL INCREASE TO AROUND 7 DEG C/KM BY 00Z WED. THUS THE IDEA
OF ELEVATED CONVECTION LATE TUESDAY INTO TUESDAY EVENING STILL
APPEARS PROBABLE...ESPECIALLY TUESDAY EVENING WHEN MID LEVEL TROUGH
AND SFC LOW TRAVERSES THE REGION. WHILE KINEMATICS SUPPORTIVE OF THE
POTENTIAL FOR STRONG CONVECTION...LACK OF SURFACE BASED INSTABILITY
WILL LIMIT SEVERE WEATHER ATTRIBUTES WITH THE CONVECTION AT THIS
TIME.
WILL MAINTAIN FORECAST CONTINUITY OF GREATER PRECIP CHANCES TUESDAY
AFTERNOON AND TUESDAY NIGHT WITH LIKELY TO CATEGORICAL POPS DURING
THIS PERIOD. DID GO WITH A SLIGHTLY SLOWER PRECIP ARRIVAL
TUESDAY MORNING. AS SYSTEM BEGINS TO DEPART THE REGION TOWARD
DAYBREAK WEDNESDAY...SHARPLY COLDER AIR ALOFT WILL BRING A THREAT OF
RAIN MIXED WITH SNOW TO THE NW PIEDMONT. -WSS
WEDNESDAY AND WEDNESDAY NIGHT:
MODELS ARE COMING INTO BETTER AGREEMENT ON WEDNESDAY... SHOWING THE
SURFACE LOW INVOF THE NC/VA BORDER NEAR THE COASTAL REGION BY 12Z
WEDNESDAY... WITH THE 500 MB LOW QUICKLY MOVING ACROSS OUR AREA AND
INTO THE SAME GENERALLY AREA BY 18Z WEDNESDAY. THE GFS/NAM/ECMWF
HAVE TRENDED A BIT DRIER ACROSS THE AREA ON WEDNESDAY (WITH LITTLE
IF ANY PRECIP ACROSS THE SOUTHWEST NOW AFTER 12Z)... WITH THE SLIGHT
JOG TO THE NORTH WITH THE TRACK OF THE LOW... ALLOWING MORE OF A
DRYING NW TO NORTHERLY FLOW IN THE WAKE OF THE PASSING MID LEVEL
LOW. HOWEVER... IT STILL APPEAR LIKELY THAT WE WILL SEE SOME PRECIP
FILL BACK IN ACROSS THE NORTHEASTERN HALF OF THE CWA WITH STEEPENING
LAPSE RATES AND A POSSIBLE DEFORMATION BAND EXTENDING ACROSS OUR
NORTH/NORTHEAST (WITH THE MORE SIGNIFICANT PRECIP TO THE
NORTH/NORTHEAST OF OUR AREA). THE GFS BEGINS TO SHOW SIGNS OF THE
SYSTEM LIFTING OFF/MEANDERING MORE NORTH/NORTHEASTWARD WEDNESDAY
AFTERNOON/NIGHT. FOR THIS REASON HAVE ELECTED TO GO WITH MORE OF A
BLEND OF THE NAM/ECMWF FOR POPS/QPF LATE WEDNESDAY MORNING THROUGH
WEDNESDAY NIGHT... AS WE THINK THE BLOCKING HIGH ALOFT ACROSS SE
CANADA SHOULD HELP PREVENT A MORE NORTH/NORTHEASTWARD TRACK (WHICH
THE GFS HAS). THUS... WITH LOW LEVEL THICKNESS CRASHING AND
SUPPORTIVE OF ALL SNOW ACROSS THE NORTHEASTERN HALF (WHERE PRECIP IS
EXPECTED AND SATURATION RETURNING INTO THE -10 TO -20 LAYER C) OF
CENTRAL NC WE MAY SEE SOME ACCUMULATING SNOW (POSSIBLY AT FIRST
MIXED WITH RAIN... DEPENDING ON TEMPS IN THE BOUNDARY LAYER AND
LOCATIONS OF THE DEFORMATION BAND ALONG WITH SATURATION ALOFT)...
ESPECIALLY ACROSS THE FAR NORTHEASTERN PIEDMONT AND NORTHERN COASTAL
PLAIN. GIVEN WE ARE STILL TALKING ABOUT THE MAIN TIME FRAME FOR
ACCUMULATING SNOWFALL BEING WEDNESDAY MID/LATE MORNING INTO THE
AFTERNOON/EARLY EVENING WE WILL NOT ISSUE A WINTER STORM WATCH AT
THIS TIME. HOWEVER... IF FORECAST MODELS CONTINUE TO INDICATE THE
DEFORMATION BAND PIVOTING THROUGH OUR NORTH/NORTHEASTERN COUNTIES
THEN A WINTER STORM WATCH MAYBE NEEDED IN FUTURE FORECAST WITH THE
POTENTIAL FOR SOME DECENT ACCUMULATIONS NORTH OF A LINE FROM ROXBORO
TO LOUISBURG TO ROCKY MOUNT. IN ADDITION TO THE THREAT OF SNOW...
WNW TO NW WINDS WILL STRENGTHEN AS AS THE SYSTEM DEEPENS AND BECOMES
MORE VERTICALLY STACKED ON WEDNESDAY. THUS... THINK WE COULD SEE
WINDS IN THE 20 TO 25 MPH RANGE SUSTAINED... WITH GUSTS AS HIGH AS
30 TO 35 MPH WEDNESDAY... WHICH COULD CREATE LOW VISBYS IN AREAS OF
SNOW. HIGH TEMPS WILL BE QUITE DIFFICULT... WITH THE PRECIP ACROSS
THE NORTHEAST... WITH SKIES EVEN BEGIN TO CLEAR OUT A BIT ACROSS THE
FAR SOUTHWEST LATE IN THE DAY. THIS WILL YIELD A NON-DIURNAL TREND.
THIS YIELDS HIGH TEMPS RANGING FROM THE MID TO UPPER 30S
NORTH/NORTHEAST TO MID TO UPPER 40S SOUTH/WEST. SKIES WILL BEGIN TO
SLOWLY CLEAR FROM SOUTHWEST TO NORTHEAST ON THURSDAY MORNING... WITH
POSSIBLY THE TREAT OF SOME BLACK ICE. EXPECT LOW TEMPS TO RANGE FROM
THE LOWER TO MID 30S. -BSD
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 230 AM MONDAY...
THE DEEP LOW PRESSURE SYSTEM (WHICH IS EXPECTED TO MOVE ACROSS THE
REGION TUESDAY INTO WEDNESDAY) WILL SHIFT SLOWLY OFF TO THE EAST OF
THE AREA LATE WEEK... WHILE SURFACE HIGH PRESSURE BUILDS INTO THE
AREA AND HEIGHTS ALOFT RISE. SUBSIDENCE BEHIND THE EXITING SYSTEM
WILL PROVIDE THE AREA WITH SUNNY TO MOSTLY SUNNY SKIES FOR LATE
WEEK. HOWEVER... GIVEN THE NORTHERLY/NORTHWESTERLY FLOW... WITH AT
TIME BREEZE SURFACE WINDS ON THURSDAY... EXPECT TEMPS WILL REMAIN
BELOW NORMAL THROUGH AT LEAST THURSDAY AND FRIDAY. THUS... WILL GO
WITH HIGHS RANGING FROM GENERALLY THE UPPER 40S TO MID 50S THURSDAY
TO THE MID TO UPPER 50S FRIDAY. LOWS DURING THIS TIME AREA EXPECTED
TO BE IN THE UPPER 20S TO LOWER 30S (FRIDAY AND SATURDAY MORNINGS).
THE SURFACE RIDGE AXIS IS EXPECTED TO SHIFT TO THE EAST OF THE AREA
ON SATURDAY... YIELDING WARMING CONDITIONS... WITH THE NEXT
SIGNIFICANT SYSTEM EXPECTED TO REMAIN TO THE WEST OF THE AREA
THROUGH THE END OF THE FORECAST PERIOD. THUS... WILL CONTINUE DRY
CONDITIONS... WITH WARMING TEMPS. HOWEVER... EXPECTED CLOUD COVER TO
INCREASE DURING THE LATTER HALF OF THE WEEKEND AS THE NEXT SYSTEM
APPROACHES... ALONG WITH POSSIBLY SOME MID AND HIGH LEVEL CLOUD
COVER ASSOCIATED WITH A PASSING NORTHERN STREAM SYSTEM. THIS YIELDS
EXPECTED HIGH TEMPS NEAR NORMAL ON SATURDAY TO LOWER TO MID 60S
SUNDAY... WITH LOW TEMPS SUNDAY MORNING IN THE UPPER 30S TO AROUND
40.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 618 AM MONDAY...
WEAK HIGH PRESSURE BUILDING INTO CENTRAL NC WILL BE ACCOMPANIED BY
DRY AIR...LEADING TO CLEAR SKIES AND A PERSISTENT NW WIND. WIND
GUSTS THIS MORNING WILL BE 18-23KTS OUT OF THE NW. GUSTS WILL BECOME
INFREQUENT BY THIS AFTERNOON...SUBSIDING AND MAINLY WLY BY THE END
OF THE DAY. THERE WILL BE AN INCREASE IN HIGH LEVEL CLOUDS
CLOUDINESS BY MID-LATE AFTERNOON. WHILE SKIES WILL BECOME OVERCAST
TONIGHT...CEILINGS WILL REMAIN VFR.
AVIATION CONDITIONS WILL DETERIORATE TUESDAY AS A STRONG LOW
PRESSURE SYSTEM BEGINS TO EXERT ITS INFLUENCE ON THE SENSIBLE
WEATHER ACROSS CENTRAL NC. AREAS OF RAIN WILL DEVELOP ACROSS CENTRAL
NC BY LATE TUESDAY MORNING...CONTINUING INTO TUESDAY NIGHT. CEILINGS
WILL BECOME LOW END MVFR/IFR BY TUESDAY AFTERNOON WITH AREAS OF LIFR
PROBABLE TUESDAY NIGHT.
A BREAK IN THE RAIN IS EXPECTED WEDNESDAY MORNING WHICH MAY ALSO SEE
CEILINGS BRIEFLY LIFT INTO THE VFR CATEGORY. ANOTHER ROUND OF
PRECIP ALONG WITH MVFR CEILINGS WILL LIKELY EFFECT THE REGION
WEDNESDAY AFTERNOON WITH THE POTENTIAL FOR THE RAIN TO BECOME MIXED
WITH SNOW PRIOR TO ENDING LATE WEDNESDAY INTO WEDNESDAY EVENING.
WINDY CONDITIONS WILL ALSO AFFECT THE REGION WEDNESDAY THROUGH
WEDNESDAY NIGHT WITH SUSTAINED WINDS NEAR 20 MPH AND GUSTS 30 TO 35
MPH.
VFR CONDITIONS ARE ANTICIPATED THURSDAY INTO FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/SMITH
SHORT TERM...WSS/BSD
LONG TERM...BSD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
900 PM CST TUE MAR 5 2013
.DISCUSSION...LATEST FOG/STRATUS IMAGERY LOOP AND SURFACE
OBSERVATIONS SHOW AREAS OF STRATUS ALONG AND SOUTH OF A LINE FROM
WILLISTON TO WATFORD CITY AND INTO CARRINGTON. NORTH OF THIS LINE
SKIES WERE GENERALLY CLEAR. HENCE...A WIDE VARIETY OF HOURLY
TEMPERATURES CAN BE EXPECTED OVERNIGHT DEPENDING ON CLOUD COVER.
THE HRRR MODEL LOW LEVEL CLOUD COVER IS THE ONLY MODEL DEPICTING A
RELATIVELY ACCURATE ANALYSIS WITH REGARDS TO SATELLITE
IMAGERY...AND HENCE HAVE USED THIS FOR THE REST OF THE NIGHT FOR
CLOUDS. ESSENTIALLY THE HRRR SLOWLY EXPANDS THE STRATUS NORTH.
HAVE INCREASED CLOUDS ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
WITH A LOW LEVEL SOUTHEAST FLOW DEVELOPING LATER TONIGHT AND BROAD
RIDGING APPROACHING FROM THE WEST...THE STRATUS MAY HOLD ON FOR
MUCH OF WEDNESDAY MORNING. TEMPERATURES WERE ADJUSTED AS WELL BUT
WITH ANY CLEAR SPOT THAT DEVELOPS...TEMPS WILL DROP QUICKLY.
REST OF FORECAST ON TRACK...DRY CONDITIONS THROUGH WEDNESDAY
AFTERNOON.
&&
.AVIATION...MVFR CIGS WILL DOMINATE ALL AERODROMES TONIGHT EXCEPT
KMOT...WHERE SKIES WILL REMAIN CLEAR UNTIL 06Z. LATEST SATELLITE
IMAGERY AND FORECASTS SHOW THAT STRATUS WILL EXPAND OVER WESTERN
AND CENTRAL NORTH DAKOTA TUESDAY NIGHT AND WILL LIKELY LINGER
WELL INTO WEDNESDAY MORNING. A RETURN TO VFR CIGS SHOULD OCCUR
AFTER 18Z WEDNESDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION/AVIATION...KS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
310 PM CST MON MAR 4 2013
.SHORT TERM...TONIGHT THROUGH THURSDAY
CHALLENGES ABOUND WITH ONGOING WINTER STORM...OF GREATEST CONCERN
WILL BE SNOW AMOUNTS AND ASSOCIATED HEADLINES. MODELS CONTINUE TO
UNDERESTIMATE THE STRENGTH OF THE DRYING FROM BOTH THE DRY SLOT TO
THE SOUTH AND ARCTIC HIGH TO THE NORTH. OVERALL...RAP SEEMS TO
HAVE THE BEST HANDLE ON REALITY AND WILL FOLLOW ITS OUTPUT AND
THE LATEST OBSERVATIONAL TRENDS FOR THE NEXT SEVERAL HOURS.
SURFACE LOW AS OF 21 UTC HAS FINALLY TURNED TO THE SOUTH...
CENTERED TO THE SOUTHEAST OF BISMARCK BY ABOUT 50 MILES. RAP SHOWS
THE SURFACE LOW CONTINUING ITS SOUTHEASTWARD TRACK...NEARING
ABERDEEN BETWEEN 03 AND 06 UTC THIS EVENING. MODERATE TO HEAVY
SNOW BAND FROM MINOT TO GRAND FORKS TO DETROIT LAKES WILL CONTINUE
TO PIVOT AROUND THE LOW...IMPACTING MOST OF THE FORECAST AREA
THIS EVENING AND THROUGH THE NIGHT. THE DRY SLOT HAS MOVED INTO
EASTERN ND ALONG AND WEST OF A LINE FROM DEVILS LAKE TO GRAND
FORKS TO FARGO AND EXPECT A BREAK IN SNOWFALL IN THIS AREA LATE
THIS AFTERNOON AND EVENING BEFORE LIGHT WRAP-AROUND SNOW MOVES
THROUGH IN THE WAKE OF THE SURFACE LOW.
HIGHEST SNOW TOTALS SO FAR HAVE BEEN ALONG AND SOUTH OF THE
CANADIAN BORDER ACROSS THE DEVILS LAKE BASIN AND INTO THE NORTHERN
VALLEY WHERE OVER A FOOT HAS ACCUMULATED. FARTHER SOUTH AND EAST
FROM EAST CENTRAL ND INTO THE CENTRAL VALLEY HAS RECEIVED 5 TO 8
INCHES. VERY LITTLE SNOW HAS FALLEN SO FAR FROM FERGUS FALLS TO
DETROIT LAKES/PARK RAPIDS NORTHWARD TO BEMIDJI AND ROSEAU/
BAUDETTE WITH ONLY AN INCH OR LESS ACCUMULATION. RAP SUGGESTS THIS
AREA WILL FILL-IN THIS EVENING AND OVERNIGHT AS THE SURFACE LOW
MOVES INTO SD AND SOUTHWEST MN. AS A RESULT...WILL KEEP WINTER
STORM WARNING IN PLACE FOR THESE AREAS WITH SNOW TOTALS BY TUESDAY
MORNING IN THE 4 TO 7 INCH RANGE. BACK TO THE NORTH AND WEST
ANOTHER 1 TO 4 INCHES ARE POSSIBLE OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ALONG AND WEST OF THE VALLEY LATE
THIS EVENING AND OVERNIGHT. ALTHOUGH NOT OVERLY STRONG...WIND
SPEEDS SHOULD BE HIGH ENOUGH FOR PERIODS OF BLOWING AND DRIFTING
SNOW AND WILL INCLUDE THIS IN THE GRIDS. WITH CLOUD COVER AND WIND
OVERNIGHT...EXPECT ELEVATED TEMPERATURES WITH TUESDAY MORNING LOWS
IN THE MID TO UPPER TEENS.
LIGHT SNOW WILL LINGER EAST OF THE VALLEY THROUGH TUESDAY MORNING
AND DEPENDING ON HOW MUCH SNOW ACCUMULATES OVERNIGHT...THE WINTER
STORM WARNING MAY NEED TO BE EXTENDED. FOR AREAS TO THE WEST...
EXPECT VERY GRADUAL DRYING AND CLEARING. HIGHS TOMORROW WILL RANGE
FROM THE UPPER TEENS TO MID 20S.
WEDNESDAY WILL BE DRY WITH PERIODS OF SUNSHINE AS SURFACE HIGH
PRESSURE BUILDS ACROSS THE REGION. WILL MAINTAIN 20 TO 30 POPS
ACROSS THE NORTH ON THURSDAY AS A SHORT-WAVE MOVES THROUGH
SOUTHWEST FLOW ALOFT. HOWEVER...LATEST MODEL TRENDS PLACE THE
MAJORITY OF SNOW NORTH OF THE BORDER...SO NOT EXPECTING MUCH IN
THE WAY OF ACCUMULATION. BY THURSDAY...TEMPERATURES WILL RISE INTO
THE UPPER 20S TO LOW 30S.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
SW FLOW ALOFT IS EXPECTED TO BEGIN THE PERIOD...WITH THE CHANCE OF
SOME SNOW THU NIGHT. THEREAFTER...THE FLOW BECOMES SOMEWHAT
SPLIT...ALTHOUGH MODELS DIFFER ON JUST HOW MUCH INFLUENCE A SOUTHERN
STREAM WAVE MAY HAVE LATER IN THE WEEKEND. FOR NOW WILL KEEP SOME
LOW POPS THU NIGHT...THEN AGAIN LATER IN THE WEEKEND INTO EARLY NEXT
WEEK FOR MAINLY THE SOUTHERN AREAS. TEMPS SHOULD MODERATE TO NEAR
NORMAL THIS WEEKEND...WITH OVERALL CONFIDENCE NOT VERY HIGH WITH
THIS FORECAST.
&&
.AVIATION...
EXPECT CONDITIONS TO VARY FROM IFR TO LOW END MVFR IN EITHER CIGS
OR VSBY IN SNOW/BLSN AT MOST TAF SITES THRU TONIGHT. EXPECT A
SOUTHEAST TO EAST WIND 15 TO 25KTS TURNING NORTH IN ERN ND LATE
TONIGHT-TUES WITH GUSTS AT TIMES TO 30KT POSSIBLE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NDZ049-052-
053.
WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR NDZ006>008-
014>016-024-026>030-038-039-054.
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR MNZ029.
WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR MNZ001>009-
013>017-022>024-027-028-030>032-040.
&&
$$
ROGERS/DK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
942 PM EST TUE MAR 5 2013
.SYNOPSIS...
A WINTER STORM WILL AFFECT THE AREA TONIGHT AND EARLY WEDNESDAY.
HIGH PRESSURE WILL BUILD ACROSS THE REGION LATE THIS WEEK...LASTING
INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
MADE SOME MINOR TWEAKS TO STORM TOTAL SNOW AND MADE ADJUSTMENTS TO
THE WEATHER GRIDS DURING THIS EVENING UPDATE. ALSO INCREASED WINDS
ACROSS THE SOUTH AND WEST AS SURFACE PRESSURE GRADIENT HAS
INCREASED ACROSS THE SOUTH...AND WILL LATER TONIGHT ACROSS THE
WEST. THIS WILL PRODUCE GUSTS OVER 30 MPH AT TIMES DURING THE
OVERNIGHT PERIOD FOR THOSE ZONES. RAIN/SNOW LINE HAS PROGRESSED TO
JUST WEST OF THE COLUMBUS AREA. PRECIPITATION WILL CONTINUE TO
TRANSITION TO SNOW ACROSS THE FAR EASTERN ZONES TOWARD
MIDNIGHT...WITH ALL SNOW FOR THOSE ZONES BY MIDNIGHT. HAVE HAD
REPORTS OF ISOLATED THUNDER ASSOCIATED WITH A STRONGER SNOW BAND
EXTENDING FROM DARKE COUNTY...SOUTHEASTWARD ACROSS WARREN COUNTY.
THESE THUNDER OCCURRENCES ARE ISOLATED IN NATURE.
THEREFORE...WILL HOLD OFF ON ADDING THE MENTION OF IT IN THE GRIDS
ATTM. THE PEAK SNOW INTENSITY WILL BE FROM NOW UNTIL A COUPLE OF
HOURS AFTER MIDNIGHT...AS THE BEST LIFT PRODUCES THE HIGHEST RATES
OF ACCUMULATION IN OUR AREA.
.PREVIOUS DISCUSSION AT 423 PM EST...
AN UPPER LOW IS DIVING SOUTHEASTWARD OUT OF THE NORTHERN PLAINS
AND INTO THE TENNESSEE VALLEY THIS EVENING. A SURFACE LOW
DEVELOPING OVER KENTUCKY...OUT AHEAD OF THE UPPER LOW WILL DEEPEN
AND PIVOT NORTHEASTWARD OVER THE OHIO VALLEY AS THE UPPER LOW
SLIDES BY TO THE SOUTH TONIGHT. PRECIPITATION IS ALREADY SPREADING
NORTHWARD ACROSS THE FORECAST AREA AHEAD OF THE INTENSIFYING
SURFACE LOW. PRECIPITATION WILL FALL AS RAIN ACROSS THE AREA INTO
THE EARLY EVENING...AS WARM AIR IS DRAWN NORTH AND WEST INTO THE
LOW LEVELS AROUND THE LOW.
THE FORECAST FOR LATER THIS EVENING BECOMES COMPLICATED...AS COLD
AIR BEGINS TO WORK ITS WAY BACK INTO THE LOW. THIS PROCESS WILL BE
TWOFOLD. LOW LEVEL COLD ADVECTION WILL ALLOW FOR COLDER AIR TO
WRAP INTO THE SURFACE LOW. AT THE SAME TIME...ABUNDANT VERTICAL
MOTION WILL PROVIDE FOR DYNAMIC COOLING FROM THE MIDDLE
LEVELS...PROPAGATING TO THE SURFACE. MODELS ARE IN AGREEMENT ON
THE STRONG VERTICAL MOTION ASSOCIATED WITH THIS SYSTEM THIS
EVENING ACROSS OUR AREA. HOWEVER...THERE ARE CRITICAL DIFFERENCES
IN HOW THE MODELS ARE HANDLING THE BATTLE BETWEEN DYNAMIC
COOLING...AND WARM AIR BEING PULLED IN AROUND THE LOW. BASED ON
HOW STRONG ASCENT IS AS HEAVIER PRECIPITATION MOVES IN THIS
EVENING...THIS FORECAST PACKAGE WENT WITH A MODERATELY FAST
CHANGEOVER TO SNOW TO BEGIN IN THE WESTERN ZONES AROUND 7
PM...SPREADING EAST THROUGH THE DAYTON/CINCY AREAS BY 9 PM...THEN
COLUMBUS BY 10 OR 11 PM. IF THE DYNAMIC COOLING PROCESS IS
STRONGER THAN THIS FORECAST IS HINTING AT...THEN THIS CHANGEOVER
WILL OCCUR SOONER...WITH THE RESULT BEING HIGHER SNOW TOTALS. OF
COURSE...IF ADDITIONAL WARMER AIR IS DRAW INTO THE SYSTEM...LIKE
THE RAP SUGGESTS THEN MORE RAIN WILL FALL INITIALLY. THE RAP
SOLUTION HAS BEEN ON THE WARM SIDE TODAY...THEREFORE AM LEANING
TOWARD THE COLDER SOLUTIONS.
ANY SNOW THAT OCCURS JUST AFTER THE CHANGEOVER WILL BE A
HEAVY...WET SNOW. THE BOTTOM LINE IS THAT THE MODELS LOOK AS IF
THEY ARE PICKING UP ON THE STRONGER LIFT BASED ON QPF AMOUNTS
RISING OVER RECENT RUNS. THIS MEANS A POTENTIAL FOR HIGHER STORM
TOTALS FOR OUR AREA. TOTAL SNOWFALL NUMBERS WERE THEREFORE TWEAKED
SLIGHTLY HIGHER...WITH THE MAXIMUM BEING AROUND 8 INCHES STORM
TOTAL ACROSS THE NORTHWESTERN ZONES. SOME OF THE SOUTHWESTERN
ZONES...WHERE A TRANSITION WILL OCCUR FIRST...MAY RECEIVE UP TO 4
INCHES OF SNOW. THE TRICKIEST SNOWFALL TOTAL FORECAST LIED WHERE
THE CENTER OF THE SURFACE LOW IS EXPECTED TO SPIN FOR A FEW HOURS
TONIGHT...ACROSS THE SCIOTO VALLEY. THERE...SNOWFALL AMOUNTS COULD
VARY QUITE A BIT...NOT ONLY DUE TO THE DELAYED CHANGEOVER DUE TO
SOME WARMER AIR...BUT THE LACK OF HEAVIER QPF UNDERNEATH THE LOW`S
CENTER LATE TONIGHT.
EXPANDED THE WINTER STORM WARNING TO INCLUDE SOME OUR OUR NORTHERN
KENTUCKY ZONES THAT ARE NOW EXPECTED TO REACH OUR 12 HOUR
CRITERIA OF 4 INCHES OF SNOW TONIGHT. DID DELAY THE START OF ALL
WARNINGS/ADVISORY EXCEPT ACROSS THE EXTREME NORTH...SINCE THAT
WARNING WAS ALREADY IN EFFECT AT THE TIME OF THE FORECAST PACKAGE
ISSUANCE.
SNOW WILL CONTINUE THROUGHOUT THE EARLY PRE-DAWN HOURS AS THE SURFACE
LOW SPINS ACROSS SOUTHEASTERN OHIO.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
THE UPPER LOW WILL QUICKLY SHIFT TOWARD THE MID ATLANTIC STATES
WEDNESDAY MORNING AS A SECONDARY SURFACE LOW DEVELOPS CLOSER TO
THE EASTERN SEABOARD. THIS ENERGY TRANSFER EASTWARD...AND AWAY
FROM OUR AREA WILL BRING A RAPID END TO FORCING SUPPORTING STEADY
SNOW IN OUR AREA. SNOW WILL TAPER OFF QUICKLY AROUND SUNRISE WITH
ONLY SOME LIGHTER SNOW SHOWERS EXPECTED DURING THE DAY.
NORTHERLY FLOW BEHIND THE DEPARTING STORM SYSTEM AND RIDGING
ACROSS THE NORTHERN PLAINS WILL KEEP A CHANCE FOR LIGHT SNOW OR
FLURRIES IN OUR AREA THROUGH WEDNESDAY NIGHT AND INTO THE DAY
THURSDAY. TEMPERATURES DURING THIS TIME PERIOD WILL REMAIN BELOW
NORMAL. LOW LEVEL MOISTURE...AND ASSOCIATED CLOUD COVER WILL
FINALLY BEGIN TO GIVE WAY TO DRIER CONDITIONS THURSDAY NIGHT...AS
THE RIDGE BUILDS ACROSS THE OHIO VALLEY. TEMPERATURES WILL LIKELY
BOTTOM OUT THURSDAY NIGHT IN THE UPPER TEENS TO LOW 20S UNDER
PARTLY CLOUDY SKIES.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AFTER A PLEASANT AND GENERALLY MILD WEEKEND...WITH GOOD MODEL
AGREEMENT...THERE IS CONSIDERABLE UNCERTAINTY ON A WEATHER SYSTEM
MOVING INTO THE REGION EARLY NEXT WEEK.
THE WEEKEND WILL BEGIN WITH A MID LEVEL TROUGH AXIS EXTENDING FROM
THE GULF OF MEXICO TO NORTHERN INDIANA. WARM ADVECTION WILL BE
UNDERWAY ALOFT...AND SHOULD BEGIN AT THE SURFACE AS WELL (AS WINDS
TAKE A SOUTHERLY COMPONENT). THIS PATTERN WILL GENERALLY CONTINUE
INTO SUNDAY...AS THE RIDGE AXIS MOVES EAST. WITH QUITE A BIT OF SUN
ON SATURDAY (PERHAPS JUST SOME LOW CLOUDS THAT ARE SLOW TO MOVE OUT
OF THE NORTHEASTERN CWA)...TEMPERATURES WILL RISE ABOVE NORMAL BY
ABOUT 5 DEGREES.
THE RIDGE WILL CONTINUE TO DOMINATE THE WEATHER ON SUNDAY...BUT AS
INFLUENCE FROM THE DEVELOPING WEATHER SYSTEM IN THE WESTERN STATES
BEGINS TO COMPLICATE THE FORECAST...SOME UNCERTAINTY WILL BEGIN TO
SET IN. MOISTURE WILL BEGIN TO ADVECT IN ALOFT...LEADING TO HIGH
CLOUDS THICKENING THROUGH THE DAY. DESPITE THIS...SURFACE WARM
ADVECTION WILL BE STRENGTHENING...LEADING TO EVEN WARMER TEMPS ON
SUNDAY.
BEYOND SUNDAY...A VERY HIGH AMOUNT OF UNCERTAINTY EXISTS IN THE
FORECAST. IT APPEARS CERTAIN THAT A WESTERN TROUGH WILL EJECT INTO
THE EASTERN STATES...AS SURFACE LOW PRESSURE DEVELOPS AND MOVES
THROUGH OR NEAR THE OHIO VALLEY. HOWEVER...THERE IS VERY LOW
CONFIDENCE IN THE TIMING OF THIS SYSTEM...AS WELL AS IN THE
PLACEMENT OF THE SURFACE LOW. DETERMINISTIC MODELS (12Z GFS VS 12Z
CMC VS 00Z ECMWF) ARE AS MUCH AS A DAY AND A HALF OFF IN
TIMING...WITH THE SURFACE LOW POSSIBLY GOING NORTH OR SOUTH OF THE
AREA. SO...AT THIS TIME...THE FORECAST WILL REMAIN VERY GENERAL.
ALTHOUGH IT IS FRUSTRATING TO GO NO HIGHER THAN 30 POPS WHEN RAIN
APPEARS A VIRTUAL CERTAINTY AT SOME POINT IN THE SUNDAY NIGHT
THROUGH TUESDAY TIME FRAME...THE TIMING DIFFERENCES ARE TOO GREAT TO
GO HIGHER.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
DYNAMIC STORM SYSTEM WILL AFFECT THE REGION THROUGH THE FIRST PART
OF THE TAF PERIOD WITH SNOW AND WIND. SURFACE LOW PRESSURE OVER
EASTERN KENTUCKY THIS EVENING WILL SWING NORTHEAST INTO SOUTHEAST
OHIO THROUGH TONIGHT. DYNAMIC LIFT ALOFT COMBINED WITH STRONG
FORCING IN THE LOW LEVELS ON THE BACK SIDE OF THE LOW WILL
TRANSITION RAIN TO SNOW FROM WEST TO EAST THIS EVENING. THE SNOW IS
EXPECTED TO BE MODERATE TO LOCALLY HEAVY AT TIMES. IT STILL LOOKS
LIKE THE BEST CHANCE FOR PROLONGED HEAVY SNOW WILL BE AT THE KDAY
TERMINAL WITH THE OTHER TERMINALS AT LEAST HEAVING A PERIOD OF
MODERATE SNOW. IN EITHER CASE...CONDITIONS WILL DETERIORATE TO
NEAR OR BELOW AIRPORT MINIMUMS. AFOREMENTIONED SURFACE LOW WILL
BEGIN TO WEAKEN OVER SOUTHEAST OHIO BETWEEN 09Z AND 12Z AS PARENT
UPPER LEVEL LOW PUSHES EAST TOWARD THE MID ATLANTIC...ALLOWING A
STRONGER SURFACE LOW DEVELOP NEAR THE COAST. THIS IS THE TYPICAL
ENERGY TRANSFER WE SEE IN THE OHIO VALLEY. SO...AS A RESULT...WE
SHOULD SEE A QUICK TAPERING OFF OF SNOW FROM NW TO SOUTHEAST
WEDNESDAY MORNING. FOR THE REMAINDER OF THE TAF PERIOD...SKIES
WILL REMAIN MOSTLY CLOUDY TO CLOUDY WITH VSBYS IMPROVING TO VFR
AND CEILINGS REMAINING IN THE MVFR RANGE BETWEEN 1500 AND 2000
FEET. GUSTY NORTH WINDS WILL BEGIN TO TAPER OFF TOWARD 00Z
THURSDAY.
OUTLOOK...MVFR CEILINGS TO LINGER INTO THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR OHZ026-034-
035-042>046-051>056-060>065-070>072-077>080.
WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR OHZ073-
074-081-082-088.
KY...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR KYZ089>093.
WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR
KYZ094>100.
IN...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...HATZOS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
620 PM EST TUE MAR 5 2013
.SYNOPSIS...
A WINTER STORM WILL AFFECT THE AREA TONIGHT AND EARLY WEDNESDAY.
HIGH PRESSURE WILL BUILD ACROSS THE REGION LATE THIS WEEK...LASTING
INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AN UPPER LOW IS DIVING SOUTHEASTWARD OUT OF THE NORTHERN PLAINS
AND INTO THE TENNESSEE VALLEY THIS EVENING. A SURFACE LOW
DEVELOPING OVER KENTUCKY...OUT AHEAD OF THE UPPER LOW WILL DEEPEN
AND PIVOT NORTHEASTWARD OVER THE OHIO VALLEY AS THE UPPER LOW
SLIDES BY TO THE SOUTH TONIGHT. PRECIPITATION IS ALREADY SPREADING
NORTHWARD ACROSS THE FORECAST AREA AHEAD OF THE INTENSIFYING
SURFACE LOW. PRECIPITATION WILL FALL AS RAIN ACROSS THE AREA INTO
THE EARLY EVENING...AS WARM AIR IS DRAWN NORTH AND WEST INTO THE
LOW LEVELS AROUND THE LOW.
THE FORECAST FOR LATER THIS EVENING BECOMES COMPLICATED...AS COLD
AIR BEGINS TO WORK ITS WAY BACK INTO THE LOW. THIS PROCESS WILL BE
TWOFOLD. LOW LEVEL COLD ADVECTION WILL ALLOW FOR COLDER AIR TO
WRAP INTO THE SURFACE LOW. AT THE SAME TIME...ABUNDANT VERTICAL
MOTION WILL PROVIDE FOR DYNAMIC COOLING FROM THE MIDDLE
LEVELS...PROPAGATING TO THE SURFACE. MODELS ARE IN AGREEMENT ON
THE STRONG VERTICAL MOTION ASSOCIATED WITH THIS SYSTEM THIS
EVENING ACROSS OUR AREA. HOWEVER...THERE ARE CRITICAL DIFFERENCES
IN HOW THE MODELS ARE HANDLING THE BATTLE BETWEEN DYNAMIC
COOLING...AND WARM AIR BEING PULLED IN AROUND THE LOW. BASED ON
HOW STRONG ASCENT IS AS HEAVIER PRECIPITATION MOVES IN THIS
EVENING...THIS FORECAST PACKAGE WENT WITH A MODERATELY FAST
CHANGEOVER TO SNOW TO BEGIN IN THE WESTERN ZONES AROUND 7
PM...SPREADING EAST THROUGH THE DAYTON/CINCY AREAS BY 9 PM...THEN
COLUMBUS BY 10 OR 11 PM. IF THE DYNAMIC COOLING PROCESS IS
STRONGER THAN THIS FORECAST IS HINTING AT...THEN THIS CHANGEOVER
WILL OCCUR SOONER...WITH THE RESULT BEING HIGHER SNOW TOTALS. OF
COURSE...IF ADDITIONAL WARMER AIR IS DRAW INTO THE SYSTEM...LIKE
THE RAP SUGGESTS THEN MORE RAIN WILL FALL INITIALLY. THE RAP
SOLUTION HAS BEEN ON THE WARM SIDE TODAY...THEREFORE AM LEANING
TOWARD THE COLDER SOLUTIONS.
ANY SNOW THAT OCCURS JUST AFTER THE CHANGEOVER WILL BE A
HEAVY...WET SNOW. THE BOTTOM LINE IS THAT THE MODELS LOOK AS IF
THEY ARE PICKING UP ON THE STRONGER LIFT BASED ON QPF AMOUNTS
RISING OVER RECENT RUNS. THIS MEANS A POTENTIAL FOR HIGHER STORM
TOTALS FOR OUR AREA. TOTAL SNOWFALL NUMBERS WERE THEREFORE TWEAKED
SLIGHTLY HIGHER...WITH THE MAXIMUM BEING AROUND 8 INCHES STORM
TOTAL ACROSS THE NORTHWESTERN ZONES. SOME OF THE SOUTHWESTERN
ZONES...WHERE A TRANSITION WILL OCCUR FIRST...MAY RECEIVE UP TO 4
INCHES OF SNOW. THE TRICKIEST SNOWFALL TOTAL FORECAST LIED WHERE
THE CENTER OF THE SURFACE LOW IS EXPECTED TO SPIN FOR A FEW HOURS
TONIGHT...ACROSS THE SCIOTO VALLEY. THERE...SNOWFALL AMOUNTS COULD
VARY QUITE A BIT...NOT ONLY DUE TO THE DELAYED CHANGEOVER DUE TO
SOME WARMER AIR...BUT THE LACK OF HEAVIER QPF UNDERNEATH THE LOW`S
CENTER LATE TONIGHT.
EXPANDED THE WINTER STORM WARNING TO INCLUDE SOME OUR OUR NORTHERN
KENTUCKY ZONES THAT ARE NOW EXPECTED TO REACH OUR 12 HOUR
CRITERIA OF 4 INCHES OF SNOW TONIGHT. DID DELAY THE START OF ALL
WARNINGS/ADVISORY EXCEPT ACROSS THE EXTREME NORTH...SINCE THAT
WARNING WAS ALREADY IN EFFECT AT THE TIME OF THE FORECAST PACKAGE
ISSUANCE.
SNOW WILL CONTINUE THROUGHOUT THE EARLY PRE-DAWN HOURS AS THE SURFACE
LOW SPINS ACROSS SOUTHEASTERN OHIO.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
THE UPPER LOW WILL QUICKLY SHIFT TOWARD THE MID ATLANTIC STATES
WEDNESDAY MORNING AS A SECONDARY SURFACE LOW DEVELOPS CLOSER TO
THE EASTERN SEABOARD. THIS ENERGY TRANSFER EASTWARD...AND AWAY
FROM OUR AREA WILL BRING A RAPID END TO FORCING SUPPORTING STEADY
SNOW IN OUR AREA. SNOW WILL TAPER OFF QUICKLY AROUND SUNRISE WITH
ONLY SOME LIGHTER SNOW SHOWERS EXPECTED DURING THE DAY.
NORTHERLY FLOW BEHIND THE DEPARTING STORM SYSTEM AND RIDGING
ACROSS THE NORTHERN PLAINS WILL KEEP A CHANCE FOR LIGHT SNOW OR
FLURRIES IN OUR AREA THROUGH WEDNESDAY NIGHT AND INTO THE DAY
THURSDAY. TEMPERATURES DURING THIS TIME PERIOD WILL REMAIN BELOW
NORMAL. LOW LEVEL MOISTURE...AND ASSOCIATED CLOUD COVER WILL
FINALLY BEGIN TO GIVE WAY TO DRIER CONDITIONS THURSDAY NIGHT...AS
THE RIDGE BUILDS ACROSS THE OHIO VALLEY. TEMPERATURES WILL LIKELY
BOTTOM OUT THURSDAY NIGHT IN THE UPPER TEENS TO LOW 20S UNDER
PARTLY CLOUDY SKIES.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AFTER A PLEASANT AND GENERALLY MILD WEEKEND...WITH GOOD MODEL
AGREEMENT...THERE IS CONSIDERABLE UNCERTAINTY ON A WEATHER SYSTEM
MOVING INTO THE REGION EARLY NEXT WEEK.
THE WEEKEND WILL BEGIN WITH A MID LEVEL TROUGH AXIS EXTENDING FROM
THE GULF OF MEXICO TO NORTHERN INDIANA. WARM ADVECTION WILL BE
UNDERWAY ALOFT...AND SHOULD BEGIN AT THE SURFACE AS WELL (AS WINDS
TAKE A SOUTHERLY COMPONENT). THIS PATTERN WILL GENERALLY CONTINUE
INTO SUNDAY...AS THE RIDGE AXIS MOVES EAST. WITH QUITE A BIT OF SUN
ON SATURDAY (PERHAPS JUST SOME LOW CLOUDS THAT ARE SLOW TO MOVE OUT
OF THE NORTHEASTERN CWA)...TEMPERATURES WILL RISE ABOVE NORMAL BY
ABOUT 5 DEGREES.
THE RIDGE WILL CONTINUE TO DOMINATE THE WEATHER ON SUNDAY...BUT AS
INFLUENCE FROM THE DEVELOPING WEATHER SYSTEM IN THE WESTERN STATES
BEGINS TO COMPLICATE THE FORECAST...SOME UNCERTAINTY WILL BEGIN TO
SET IN. MOISTURE WILL BEGIN TO ADVECT IN ALOFT...LEADING TO HIGH
CLOUDS THICKENING THROUGH THE DAY. DESPITE THIS...SURFACE WARM
ADVECTION WILL BE STRENGTHENING...LEADING TO EVEN WARMER TEMPS ON
SUNDAY.
BEYOND SUNDAY...A VERY HIGH AMOUNT OF UNCERTAINTY EXISTS IN THE
FORECAST. IT APPEARS CERTAIN THAT A WESTERN TROUGH WILL EJECT INTO
THE EASTERN STATES...AS SURFACE LOW PRESSURE DEVELOPS AND MOVES
THROUGH OR NEAR THE OHIO VALLEY. HOWEVER...THERE IS VERY LOW
CONFIDENCE IN THE TIMING OF THIS SYSTEM...AS WELL AS IN THE
PLACEMENT OF THE SURFACE LOW. DETERMINISTIC MODELS (12Z GFS VS 12Z
CMC VS 00Z ECMWF) ARE AS MUCH AS A DAY AND A HALF OFF IN
TIMING...WITH THE SURFACE LOW POSSIBLY GOING NORTH OR SOUTH OF THE
AREA. SO...AT THIS TIME...THE FORECAST WILL REMAIN VERY GENERAL.
ALTHOUGH IT IS FRUSTRATING TO GO NO HIGHER THAN 30 POPS WHEN RAIN
APPEARS A VIRTUAL CERTAINTY AT SOME POINT IN THE SUNDAY NIGHT
THROUGH TUESDAY TIME FRAME...THE TIMING DIFFERENCES ARE TOO GREAT TO
GO HIGHER.
&&
.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
DYNAMIC STORM SYSTEM WILL AFFECT THE REGION THROUGH THE FIRST PART
OF THE TAF PERIOD WITH SNOW AND WIND. SURFACE LOW PRESSURE OVER
EASTERN KENTUCKY THIS EVENING WILL SWING NORTHEAST INTO SOUTHEAST
OHIO THROUGH TONIGHT. DYNAMIC LIFT ALOFT COMBINED WITH STRONG
FORCING IN THE LOW LEVELS ON THE BACK SIDE OF THE LOW WILL
TRANSITION RAIN TO SNOW FROM WEST TO EAST THIS EVENING. THE SNOW IS
EXPECTED TO BE MODERATE TO LOCALLY HEAVY AT TIMES. IT STILL LOOKS
LIKE THE BEST CHANCE FOR PROLONGED HEAVY SNOW WILL BE AT THE KDAY
TERMINAL WITH THE OTHER TERMINALS AT LEAST HEAVING A PERIOD OF
MODERATE SNOW. IN EITHER CASE...CONDITIONS WILL DETERIORATE TO
NEAR OR BELOW AIRPORT MINIMUMS. AFOREMENTIONED SURFACE LOW WILL
BEGIN TO WEAKEN OVER SOUTHEAST OHIO BETWEEN 09Z AND 12Z AS PARENT
UPPER LEVEL LOW PUSHES EAST TOWARD THE MID ATLANTIC...ALLOWING A
STRONGER SURFACE LOW DEVELOP NEAR THE COAST. THIS IS THE TYPICAL
ENERGY TRANSFER WE SEE IN THE OHIO VALLEY. SO...AS A RESULT...WE
SHOULD SEE A QUICK TAPERING OFF OF SNOW FROM NW TO SOUTHEAST
WEDNESDAY MORNING. FOR THE REMAINDER OF THE TAF PERIOD...SKIES
WILL REMAIN MOSTLY CLOUDY TO CLOUDY WITH VSBYS IMPROVING TO VFR
AND CEILINGS REMAINING IN THE MVFR RANGE BETWEEN 1500 AND 2000
FEET. GUSTY NORTH WINDS WILL BEGIN TO TAPER OFF TOWARD 00Z
THURSDAY.
OUTLOOK...MVFR CEILINGS TO LINGER INTO THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR OHZ026-034-
035-042>046-051>056-060>065-070>072-077>080.
WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR OHZ073-
074-081-082-088.
KY...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR KYZ089>093.
WINTER WEATHER ADVISORY UNTIL 1 PM EST WEDNESDAY FOR
KYZ094>100.
IN...WINTER STORM WARNING UNTIL 1 PM EST WEDNESDAY FOR INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...HATZOS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1230 AM EST MON MAR 4 2013
.SYNOPSIS...
SNOW SHOWERS TAPERING OFF AS UPPER LEVEL LOW LOSES ITS GRIP
OVERNIGHT. HIGH PRESSURE CROSSES MONDAY. STRENGTHENING LOW PRESSURE
SYSTEM CROSSES TUESDAY THROUGH WEDNESDAY. DRIER THURSDAY AND FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
SEND A QUICK UPDATE TO ADJUST CLOUD COVER PER SFC OBS AND
SATELLITE IMAGES SHOWING IMPROVING CLOUD COVER HIGHER THAN
EXPECTED. AREAS OF CLEARING OVER OH WILL GRADUALLY MOVE OVER
SOUTHEAST OH AND WV FROM WEST TO EAST THROUGH MONDAY MORNING.
POPULATED NEW RAP HOURLY WINDS WEAKER THAN EXPECTED PER WEAKER
PRESSURE GRADIENT FROM A BUILDING HIGH PRESSURE EXTENDING FROM THE
SOUTHEAST STATES...NORTH ACROSS THE OH VALLEY INTO THE GREAT
LAKES. KEPT LOW CHANCE POPS AND TEMPERATURES ARE THEY REMAIN ON
TRACK. EXPECTING LIGHT SNOW OR FLURRIES MAINLY EAST HALF OF THE
CWA UNDER MID LEVEL DECK...TO MOVE EAST DURING THE PREDAWN HOURS.
PREVIOUS DISCUSSION BELOW...
930 PM UPDATE...
FCST REMAINS ON TRACK.
630 PM UPDATE...
FCST LARGELY ON TRACK OTHER THAN TO SLOW CLEARING A BIT INTO MON
MORNING.
PREV DISCN...
UPPER LEVEL LOW OVER THE NE CONUS FINALLY LOSING ITS GRIP ON OUR
WEATHER...AND WE SHOULD SEE SNOW SHOWERS TAPERING OFF FROM WEST TO
EAST ACROSS THE FORECAST AREA TONIGHT INTO EARLY MONDAY MORNING. ONE
WRENCH IN THE SYSTEM IS ONE FINAL WAVE CURRENTLY OVER CENTRAL
MICHIGAN PER THE WATER VAPOR LOOP. NAM AND ECMWF BRING IT INTO OHIO
AS A CLOSED LOW...THEN OPEN IT UP AS IT CROSSES INTO WEST
VIRGINIA...WHILE THE GFS AND CANADIAN OPEN IT UP SOONER. EITHER
WAY...THERE WILL BE SOME UPPER LEVEL SUPPORT WITH THIS BUT THE LOW
LEVEL MOISTURE IS ALL BUT GONE. MAY SEE SOME ISOLATED SNOW SHOWERS
TONIGHT ACROSS THE LOWLANDS...BUT BETTER CHANCE IN THE NORTHERN
MOUNTAINS WHERE THE BEST...ALBEIT MEAGER...MOISTURE REMAINS. THIS
FINAL WAVE WILL FINALLY GET THE THERMAL TROUGH MOVING. EXPECT
COLDEST 925 AND 850MB TEMPS TONIGHT...WITH SINGLE DIGITS IN THE
MOUNTAINS AND TEENS TO 20S ELSEWHERE. AS THERMAL TROUGH FINALLY
WEAKENS TEMPS WILL REBOUND SOME ON MONDAY AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
ACTIVE WEATHER RETURNS IN THE NEAR TERM PERIOD AS A STRONG LOW
PRESSURE SYSTEM APPROACHES THE AREA FROM THE WEST. STILL SOME
DIFFERENCES BETWEEN THE MODELS DURING THIS TIME...WITH THE GFS AND
NAM FASTER WITH THE SYSTEM...ESPECIALLY WHEN IT COMES TO EXITING TO
THE EAST OF THE CWA...THAN THE ECMWF...AND WITH THE ECMWF CONTINUING
TO KEEP THE LOW FARTHER SOUTH THAN THE AFOREMENTIONED MODELS. AT
THIS POINT...TENDED TO DO A BLEND BETWEEN THE MODELS CONCERNING THE
POPS. AS A RESULT...STILL A BIT OF UNCERTAINTY IN HOW MUCH SNOW WILL
OCCUR IN THE FORECAST...PARTICULARLY ACROSS THE NORTHERN AND EASTERN
ZONES.
AT THIS POINT...WARM FRONTAL BOUNDARY WILL LIFT NORTH ACROSS THE CWA
ON TUESDAY...SPREADING PRECIPITATION INTO THE CWA...NORTH TO SOUTH
AS IT DOES SO. DEPENDING ON THE TIMING OF THE PRECIPITATION...WHICH
MAY INITIALLY BE DELAYED A BIT DUE TO DRIER LOWER LAYERS OF THE
ATMOSPHERE...COULD SEE PRECIPITATION ACROSS SOUTHERN ZONES START OUT
AS SNOW OR A MIX...BEFORE TRANSITIONING OVER TO RAIN AS WARMER AIR
TAKES HOLD. HIGHER TERRAIN...SUCH AS AREAS OVER RANDOLPH/POCAHONTAS
COUNTIES APPEAR AS THOUGH THEY WONT SEE A COMPLETE CHANGEOVER TO
LIQUID...AND MAY EVEN HAVE BRIEF PERIODS OF SLEET TUESDAY LATE
MORNING/AFTERNOON...BEFORE COMPLETELY CHANGING OVER TO SNOW.
PRECIPITATION WILL GRADUALLY CHANGE OVER TO SNOW TUESDAY
EVENING/TUESDAY NIGHT ACROSS THE CWA AS UPPER LOW DEEPENS ACROSS THE
REGION...AND COLDER AIR WORKS ITS WAY INTO THE AREA. AT THIS
POINT...THIS COULD BE A SIGNIFICANT SNOW MAKER...PARTICULARLY ACROSS
THE HIGHER TERRAIN COUNTIES...PARTICULARLY IF THE ECMWF SOLUN HOLDS
TRUE AND IS SLOWER TO EXIT THE CWA...THUS HOLDING ON TO HIGHER
AMOUNTS OF QPF LONGER. AT THIS POINT...WILL NOT ISSUE A WATCH FOR
MOUNTAINOUS COUNTIES PER COORDINATION WITH SURROUNDING OFFICES...AND
SOME MODEL UNCERTAINTY. AT THIS POINT...FIGURING A FEW INCHES
POSSIBLE ACROSS MOST OF THE LOWLAND COUNTIES... EXCEPT FOR MAYBE
EXTREME SOUTHERN/WESTERN ZONES WHERE NOT AS MUCH QPF WILL BE
REALIZED WHEN TEMPERATURES ARE COLD ENOUGH FOR THE GENERATION OF
SNOW. NORTHERN LOWLAND COUNTIES WILL SEE THE MOST SNOW OF THE
LOWLANDS...WHERE 2 TO 4 INCHES MAY BE THE GENERAL RULE WITH SOME
LOCALLY HIGHER AMOUNTS POSSIBLE. ACROSS THE HIGHER TERRAIN
COUNTIES...GENERALLY 6 TO 12 INCHES...WITH HIGHER AMOUNTS POSSIBLE
ACROSS THE PEAKS. OF COURSE THIS IS ALL PRELIMINARY...AND WILL
DEPEND ON A VARIETY OF FACTORS. ONE THING TO NOTE IS IT WILL BE A
HEAVY WET SNOW...AND ANY ACCUMULATIONS COULD RESULT IN PROBLEMS.
WILL HIGHLIGHT SNOWFALL POTENTIAL IN THE HWO FOR NOW.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
NO MAJOR CHANGES. WILL CONTINUE TO HOLD ONTO LINGERING SNOW SHOWERS
LONGER THAN HPC MEDIUM RANGE GUIDANCE FOR WEDNESDAY NIGHT INTO
THURSDAY MORNING. HOWEVER...850 TEMPERATURES IN THE THERMAL TROF ARE
ONLY MINUS 6 TO MINUS 8...NOT THE IDEAL CRYSTAL GROWTH
TEMPERATURES. SO DESPITE CLOUDS AND HIGHER POPS... NOT THINKING
MUCH IN WAY OF ACCUMULATION OVERNIGHT...WITH AN INCH OR TWO
WEDNESDAY NIGHT OVER THE WV MOUNTAIN COUNTIES.
THE MARCH ENVIRONMENT FINALLY SETTLES DOWN FOR THURSDAY INTO
SATURDAY. A WEAK FEATURE MAY SAG SOUTH FROM THE NORTH...BY SATURDAY
NIGHT...BUT MOISTURE IS LIMITED. WILL LEAVE SOME 20/30 POPS ACROSS
THE NORTH.
DEEPER MOISTURE MAY FINALLY ARRIVE TOWARD SUNDAY NIGHT...AS THIS
PERIOD ENDS.
HELD DOWN MAXIMUM TEMPERATURES A BIT FOR THURSDAY INTO FRIDAY DUE
TO THE MELTING SNOW...BUT THEN FLIRTING WITH 60 BY SATURDAY FOR MUCH
OF SOUTHERN LOWLANDS.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS EXPECTED OVERNIGHT OVER MOST SITES. LOW CHANCE OF
LIGHT SNOW SHOWERS OR FLURRIES STILL POSSIBLE ACROSS EASTERN HALF
OF THE CWA...INCLUDING CRW...CKB...EKN AND BKW UNTIL THE MID DECK
VANISHES FOLLOWED BY MOSTLY CLEAR SKIES EARLY MONDAY. RELAXED
PRESSURE GRADIENT THANKS TO A BUILDING HIGH PRESSURE IS
RESPONSIBLE FOR WEAK TO CALM FLOW OVERNIGHT AND CLEARING SPREADING
FROM WEST TO EAST LATE OVERNIGHT...AND REMAINING INTO MONDAY.
HIGH CLOUDS FROM THE NEXT SYSTEM WILL BE MOVING IN FROM THE
SOUTHWEST MON AFTERNOON...UNDER WEAK FLOW. SOUNDING PROFILES SHOW
STRONG SUBSIDENCE AND VERY DRY AIRMASS AT THE MID LEVELS THROUGH
MONDAY EVENING...UNDER LIGHT TO MODERATE NORTHWEST ALOFT.
MODELS SHOW WARM AIR ADVECTION FROM THE SOUTHWEST AT H850 AHEAD OF
THE NEXT LOW PRESSURE SYSTEM MONDAY NIGHT. AN ASSOCIATED WARM
FRONT WILL BRING PERIODS OF RAIN SPREADING FROM SOUTHWEST TO
NORTHEAST ON TUESDAY FOR MAINLY MVFR CONDITIONS. DEPENDING OF SFC
TEMPERATURES...THERE COULD BE A SHORT PERIOD OF FREEZING RAIN
EARLY TUESDAY WITH THE ONSET OF PCPN. DIFFERENCES IN MODELS
TIMINGS PROVIDE LOW CONFIDENCE FOR FREEZING RAIN.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z TUESDAY...
FORECAST CONFIDENCE...HIGH 06Z TAFS. MEDIUM BEYOND 09Z TUESDAY.
ALTERNATE SCENARIOS: TIMING AND PCPN TYPE EARLY TUESDAY MAY VARY
DEPENDING ON THE ONSET OF PCPN AND SFC TEMPERATURES.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE MON 03/04/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L L L L L L L L L H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY L L L L L L L L H H H H
AFTER 06Z TUESDAY...
IFR VISIBILITIES AND CEILINGS POSSIBLE IN RAIN/SNOW TUESDAY INTO
THURSDAY...LINGERING THE LONGEST IN THE WV MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/TRM/MZ
NEAR TERM...ARJ/TRM/MZ
SHORT TERM...ARJ
LONG TERM...KTB
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1015 AM CST MON MAR 4 2013
.DISCUSSION.../ISSUED AT 1015 AM CST/
NARROW FAST MOVING BAND OF SNOW SHOWERS MOVING ACROSS FAR EASTERN SD
HAS REQUIRED SOME SHORT TERM VERY FINE TUNING OF GRIDS FOR THE END
OF THE MORNING...AND MAY HAVE TO EXTEND THAT INTO THIS AFTERNOON.
FORTUNATELY IT IS TOO NARROW AND MOVING TOO FAST TO PROVIDE MORE
THAN A QUARTER INCH OR SO OF SNOW. THIS IS NOT DIRECTLY ASSOCIATED
WITH THE UPPER SUPPORT THAT IS EXPECTED TO PROVIDE LIFT FOR THE
REDEVELOPMENT OF SNOW OVER SOUTHWEST MN BACK TO BROOKINGS LATER THIS
AFTERNOON AS THE UPPER LOW DIGS IN AND ROTATES...BUT THAT
DEVELOPMENT SHOULD BE FAST ALSO...AND SO FAR HAVE NOT SEEN A NEED TO
CHANGE. HAVE DROPPED THE FRINGE ADVISORY AREA WHICH INCLUDES SIOUX
FALLS WITH NO FREEZING RAIN OR FREEZING DRIZZLE...BUT HAVE KEPT IT
FURTHER NORTHEAST DESPITE SEVERAL HOURS OF LITTLE HAPPENING OUTSIDE
THESE SNOW SHOWERS...FOR THE VERY REASON OF RAPID REDEVELOPMENT.
WINDS AND TEMPERATURES LOOK OK AND NO REASON AT THIS TIME TO CHANGE
WIND ADVISORY FOR LATE TONIGHT INTO TUESDAY WEST AND FAR SOUTH.
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
LARGELY MVFR STRATUS BEGINNING TO SPREAD BACK ACROSS WESTERN PARTS
OF FORECAST AREA WHILE EASTERN AREAS REMAIN UNDER LINGERING MVFR/IFR
CEILINGS. RAP CONTINUES TO HAVE BEST GRASP ON NEAR TERM MOISTURE AND
PRECIPITATION TRENDS...AND ASIDE FROM NARROW BAND OF SHOWERY PRECIP
RIGHT ALONG A WIND SHIFT LINE ENTERING FAR WESTERN FORECAST AREA
WHICH COULD AFFECT KHON AT THE START OF THE PERIOD...EXPECT LARGELY
DRY FORECAST FOR THE TAF SITES THROUGH THE DAY. HOWEVER...AS THIS
FEATURE TRANSLATES EAST INTO I-29 CORRIDOR...MID LEVEL MOISTURE
BECOMES MORE SCARCE... BUT ENOUGH WEAK LIFT PERSISTS ABOVE STRATUS
DECK THAT WILL KEEP BRIEF PERIOD OF POTENTIAL FREEZING DRIZZLE
AROUND KFSD LATER IN THE MORNING. MID LEVEL MOISTURE INCREASES EAST
OF I-29...BRINGING GREATER CHANCE OF MVFR-OCCASIONAL IFR VISIBILITY
IN -SN TO SOUTHWEST MINNESOTA THIS AFTERNOON. BETTER CHANCE FOR SOME
LIGHT SNOWFALL RETURNS TO TAF SITES AFTER THIS EVENING...AS MOISTURE
WRAPS BACK INTO AREA BEHIND EXITING WAVE. GREATER AVIATION CONCERN
FOR LATTER PART OF THE PERIOD WILL BE INCREASING WINDS BEHIND THE
SYSTEM...ESPECIALLY THROUGH THE JAMES AND WESTERN MISSOURI RIVER
CORRIDOR BY VERY LATE AFTERNOON...EXPANDING EASTWARD IN THE EVENING.
SURFACE WIND GUSTS OF 25 TO 35 KNOTS LIKELY DURING THE LATER EVENING
AND OVERNIGHT.
&&
.PREV DISCUSSION.../ISSUED AT 410 AM CST/
CURRENT SATELLITE AND RADAR VERY EARLY THIS MORNING SHOWING A DRY
SLOT OVERSPREADING OUR AREA WITH THE ONLY RADAR RETURNS BEING
CONFINED TO OUR FAR NORTHEAST FROM MARSHALL TO JACKSON. IN LIGHT OF
THIS...CUT BACK A GOOD BIT ON POPS THROUGH THE MORNING HOURS WITH
PRECIPITATION REDEVELOPMENT PROBABLY NOT OCCURRING UNTIL THE UPPER
LEVEL WAVE PRESENTLY OVER EASTERN MONTANA BEGINS TO DROP
SOUTHEASTWARD...EXERTING INFLUENCE ON OUR AREA BY AFTERNOON. HAVE
HAD SOME VERY LIGHT FREEZING RAIN AND DRIZZLE OVER PORTIONS OF OUR
NORTHERN AND EASTERN AREAS OVERNIGHT...AND WITH STRATUS OOZING INTO
THE AREA FROM THE NORTHWEST CANNOT RULE OUT PATCHY FREEZING DRIZZLE
IN SOME LOCALES DURING THE MORNING. IN LIGHT OF THE ABOVE
TRENDS...READJUSTED CURRENT HEADLINES BY DROPPING THE WESTERN AND
SOUTHERN PORTIONS OF OUR ADVISORY THAT WENT THROUGH 18Z WITH LITTLE
ELSE EXPECTED...BUT KEPT THE ADVISORY OVER OUR NORTHEASTERN CWA
THOUGH EXTENDING IT 6 HOURS...12Z TO 18Z TUESDAY...WITH LIGHT SNOW
PERSISTING OVER THAT AREA INTO THAT TIME FRAME. THE PRECIPITATION
POTENTIAL WILL PICK UP IN OUR EAST BY THIS AFTERNOON INTO THIS
EVENING AS LIFT INCREASES OVER THAT AREA AS THE AFOREMENTIONED UPPER
LEVEL WAVE TRACKS ACROSS THE REGION. TEMPERATURES ALOFT WILL SUPPORT
SNOW BY THAT POINT...THOUGH AREAS ALONG THE WESTERN AND SOUTHERN
FRINGES OF THE PRECIPITATION SHIELD COULD BE MIXED WITH OR BE IN THE
FORM OF PLAIN RAIN WITH SURFACE TEMPERATURES IN THE MID AND UPPER
30S.
THE CRUX OF THE BETTER LIFT WILL BE LOCATED THROUGH OUR NORTHEASTERN
ZONES TONIGHT INTO EARLY ON TUESDAY PER UPPER LEVEL DIV Q
FIELDS...AND THIS IS WHEN MOST OF THE SNOW WILL OCCUR OVER THAT
AREA. STILL LOOKING AT 2 TO 4 INCHES OF ACCUMULATION OVER THE
ADVISORY AREA...GENERALLY IN A LINE FROM BROOKINGS TO SPENCER
EASTWARD. IN ADDITION...NORTHWESTERLY WINDS WILL PICK UP OVERNIGHT
WITH STRONG COLD AIR ADVECTION AND A TIGHTENING GRADIENT ON THE
BACKSIDE OF THE EXITING INVERTED SURFACE TROUGH. THE STRONGEST WINDS
LOOK TO BE ALONG THE MISSOURI RIVER CORRIDOR...AND KEPT THE WIND
ADVISORY...THOUGH EXPANDED SLIGHTLY...FOR THAT AREA STARTING EARLY
TONIGHT AND GOING THROUGH 18Z ON TUESDAY. WITH THE COLD AIR
ADVECTION WE WILL HAVE FALLING TEMPERATURES...THOUGH READINGS WILL
REMAIN IN CHECK WITH THE STRONG WINDS...BOTTOMING OUT IN THE UPPER
TEENS TO LOWER 20S BY EARLY TUESDAY MORNING.
FORCING AND ANY DEEPER MOISTURE PULL AWAY FROM THE AREA ON
TUESDAY...WITH SNOW DIMINISHING IN OUR EAST THROUGH THE MORNING AND
EARLY AFTERNOON HOURS. WITH DECREASING CLOUDS IN THE AFTERNOON UNDER
THE INFLUENCE OF SUBSIDENCE AS HIGH PRESSURE BUILDS INTO OUR WEST.
HIGHS LOOK TO BE IN THE 20S. THE SURFACE RIDGE AXIS SLIDES ACROSS
OUR CWA ON TUESDAY NIGHT...AND WITH DYING WINDS AND CLEARING SKIES
IT WILL BE A COLD NIGHT. LOWS WILL RANGE FROM THE LOWER SINGLE
DIGITS IN OUR NORTHEAST WHERE FRESH SNOW COVER WILL RESIDE...TO JUST
ABOVE 10 ALONG THE MISSOURI RIVER CORRIDOR.
A SOUTHERLY FLOW RETURNS TO THE REGION ON WEDNESDAY AS HIGH PRESSURE
PUSHES OFF TO THE EAST. WITH WARMING THERMAL PROFILES HIGHS WILL
APPROACH 40 IN OUR SOUTH CENTRAL SOUTH DAKOTA ZONES...TAPERING
DOWNWARD TO THE NORTH AND EAST WITH HIGHS ONLY IN THE LOWER 20S IN
OUR SOUTHWESTERN MINNESOTA AREAS WHICH WILL HAVE DEEPER SNOW COVER.
LONG RANGE THURSDAY THROUGH SUNDAY STARTS OFF WITH FAIRLY GOOD
AGREEMENT AMONG THE MODELS...SHOWING LONG WAVE RIDGE IN PLACE ACROSS
THE AREA WITH WEAK NORTHERN STREAM SHORTWAVE TOPPING THE RIDGE NORTH
OF THIS FORECAST AREA. MILD LOW LEVEL AIR IN PLACE WITH 850MB TEMPS
ABOVE 0C THROUGH FRIDAY WILL BRING TEMPERATURES CLOSER TO SEASONAL
NORMALS THAN WE HAVE SEEN OF LATE...WITH AREAS WEST OF THE JAMES
RIVER MOST LIKELY TO SEE READINGS CLIMB WELL ABOVE NORMAL THURSDAY.
CONFIDENCE DECREASES SIGNIFICANTLY IN THE LATTER PART OF THE PERIOD
AS MODELS SHOW MUCH GREATER DIVERGENCE IN HANDLING STRONG SOUTHERN
STREAM TROUGH WHICH DIGS THROUGH THE DESERT SOUTHWEST LATE THIS
WEEK. ECMWF SWINGING A CUTOFF LOW OUT INTO THE CENTRAL PLAINS NEXT
WEEKEND...WITH 04/00Z RUN STRONGER/FARTHER NORTH THAN 03/12Z RUN...
THOUGH BOTH WOULD PRODUCE A PERIOD OF SIGNIFICANT PRECIPITATION
ACROSS THIS AREA AT SOME POINT NEXT WEEKEND. OPERATIONAL GFS...ON
THE OTHER HAND...KICKS ONE PIECE OF ENERGY INTO THE PLAINS FOR
SATURDAY...BUT OTHERWISE HOLDS MAIN UPPER TROUGH OVER THE DESERT
SOUTHWEST WITH LARGELY DRY CONDITIONS FOR THE LATTER HALF OF THE
WEEKEND. GFS ENSEMBLE NOT MUCH HELP AS ITS MEAN IS MORE PROGRESSIVE
BUT MUCH FARTHER SOUTH THAN ECMWF WITH CLOSED LOW KICKING OUT INTO
THE SOUTHERN PLAINS...KEEPING PRIMARY PRECIPITATION THREAT SOUTH OF
THIS AREA. GIVEN THE DISPARITY IN SOLUTIONS AT THIS RANGE...WILL NOT
VARY MUCH OF BROAD MODEL CONSENSUS...WHICH HOLDS ONTO A SMALL CHANCE
OF PRECIP ACROSS OUR SOUTH FRIDAY NIGHT THROUGH SATURDAY NIGHT...
FOLLOWED BY SLIGHTLY GREATER CHANCES SPREADING FARTHER NORTH ACROSS
THE FORECAST AREA ON SUNDAY. TEMPERATURES WILL LIKEWISE BE HELD NEAR
CONSENSUS...WHICH IS GENERALLY ON THE COOL SIDE OF NORMAL WITH HIGHS
IN THE 30S/AROUND 40...BUT VARIANCE IN SOLUTIONS LEADS TO ADDITIONAL
CONCERNS REGARDING PRECIPITATION TYPE...AND WILL KEEP THIS RATHER
GENERIC WITH CHANCE OF RAIN OR SNOW WORDING THROUGHOUT THE PERIOD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
SDZ050-052-057>060-063>066-068>071.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR SDZ040-056.
MN...WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR MNZ071-072-
080-081-089-090-097.
IA...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
IAZ031.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR IAZ002-003-
014.
NE...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY
FOR NEZ013-014.
&&
$$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
559 AM CST MON MAR 4 2013
.DISCUSSION.../ISSUED AT 410 AM CST/
CURRENT SATELLITE AND RADAR VERY EARLY THIS MORNING SHOWING A DRY
SLOT OVERSPREADING OUR AREA WITH THE ONLY RADAR RETURNS BEING
CONFINED TO OUR FAR NORTHEAST FROM MARSHALL TO JACKSON. IN LIGHT OF
THIS...CUT BACK A GOOD BIT ON POPS THROUGH THE MORNING HOURS WITH
PRECIPITATION REDEVELOPMENT PROBABLY NOT OCCURRING UNTIL THE UPPER
LEVEL WAVE PRESENTLY OVER EASTERN MONTANA BEGINS TO DROP
SOUTHEASTWARD...EXERTING INFLUENCE ON OUR AREA BY AFTERNOON. HAVE
HAD SOME VERY LIGHT FREEZING RAIN AND DRIZZLE OVER PORTIONS OF OUR
NORTHERN AND EASTERN AREAS OVERNIGHT...AND WITH STRATUS OOZING INTO
THE AREA FROM THE NORTHWEST CANNOT RULE OUT PATCHY FREEZING DRIZZLE
IN SOME LOCALES DURING THE MORNING. IN LIGHT OF THE ABOVE
TRENDS...READJUSTED CURRENT HEADLINES BY DROPPING THE WESTERN AND
SOUTHERN PORTIONS OF OUR ADVISORY THAT WENT THROUGH 18Z WITH LITTLE
ELSE EXPECTED...BUT KEPT THE ADVISORY OVER OUR NORTHEASTERN CWA
THOUGH EXTENDING IT 6 HOURS...12Z TO 18Z TUESDAY...WITH LIGHT SNOW
PERSISTING OVER THAT AREA INTO THAT TIME FRAME. THE PRECIPITATION
POTENTIAL WILL PICK UP IN OUR EAST BY THIS AFTERNOON INTO THIS
EVENING AS LIFT INCREASES OVER THAT AREA AS THE AFOREMENTIONED UPPER
LEVEL WAVE TRACKS ACROSS THE REGION. TEMPERATURES ALOFT WILL SUPPORT
SNOW BY THAT POINT...THOUGH AREAS ALONG THE WESTERN AND SOUTHERN
FRINGES OF THE PRECIPITATION SHIELD COULD BE MIXED WITH OR BE IN THE
FORM OF PLAIN RAIN WITH SURFACE TEMPERATURES IN THE MID AND UPPER
30S.
THE CRUX OF THE BETTER LIFT WILL BE LOCATED THROUGH OUR NORTHEASTERN
ZONES TONIGHT INTO EARLY ON TUESDAY PER UPPER LEVEL DIV Q
FIELDS...AND THIS IS WHEN MOST OF THE SNOW WILL OCCUR OVER THAT
AREA. STILL LOOKING AT 2 TO 4 INCHES OF ACCUMULATION OVER THE
ADVISORY AREA...GENERALLY IN A LINE FROM BROOKINGS TO SPENCER
EASTWARD. IN ADDITION...NORTHWESTERLY WINDS WILL PICK UP OVERNIGHT
WITH STRONG COLD AIR ADVECTION AND A TIGHTENING GRADIENT ON THE
BACKSIDE OF THE EXITING INVERTED SURFACE TROUGH. THE STRONGEST WINDS
LOOK TO BE ALONG THE MISSOURI RIVER CORRIDOR...AND KEPT THE WIND
ADVISORY...THOUGH EXPANDED SLIGHTLY...FOR THAT AREA STARTING EARLY
TONIGHT AND GOING THROUGH 18Z ON TUESDAY. WITH THE COLD AIR
ADVECTION WE WILL HAVE FALLING TEMPERATURES...THOUGH READINGS WILL
REMAIN IN CHECK WITH THE STRONG WINDS...BOTTOMING OUT IN THE UPPER
TEENS TO LOWER 20S BY EARLY TUESDAY MORNING.
FORCING AND ANY DEEPER MOISTURE PULL AWAY FROM THE AREA ON
TUESDAY...WITH SNOW DIMINISHING IN OUR EAST THROUGH THE MORNING AND
EARLY AFTERNOON HOURS. WITH DECREASING CLOUDS IN THE AFTERNOON UNDER
THE INFLUENCE OF SUBSIDENCE AS HIGH PRESSURE BUILDS INTO OUR WEST.
HIGHS LOOK TO BE IN THE 20S. THE SURFACE RIDGE AXIS SLIDES ACROSS
OUR CWA ON TUESDAY NIGHT...AND WITH DYING WINDS AND CLEARING SKIES
IT WILL BE A COLD NIGHT. LOWS WILL RANGE FROM THE LOWER SINGLE
DIGITS IN OUR NORTHEAST WHERE FRESH SNOW COVER WILL RESIDE...TO JUST
ABOVE 10 ALONG THE MISSOURI RIVER CORRIDOR.
A SOUTHERLY FLOW RETURNS TO THE REGION ON WEDNESDAY AS HIGH PRESSURE
PUSHES OFF TO THE EAST. WITH WARMING THERMAL PROFILES HIGHS WILL
APPROACH 40 IN OUR SOUTH CENTRAL SOUTH DAKOTA ZONES...TAPERING
DOWNWARD TO THE NORTH AND EAST WITH HIGHS ONLY IN THE LOWER 20S IN
OUR SOUTHWESTERN MINNESOTA AREAS WHICH WILL HAVE DEEPER SNOW COVER.
LONG RANGE THURSDAY THROUGH SUNDAY STARTS OFF WITH FAIRLY GOOD
AGREEMENT AMONG THE MODELS...SHOWING LONG WAVE RIDGE IN PLACE ACROSS
THE AREA WITH WEAK NORTHERN STREAM SHORTWAVE TOPPING THE RIDGE NORTH
OF THIS FORECAST AREA. MILD LOW LEVEL AIR IN PLACE WITH 850MB TEMPS
ABOVE 0C THROUGH FRIDAY WILL BRING TEMPERATURES CLOSER TO SEASONAL
NORMALS THAN WE HAVE SEEN OF LATE...WITH AREAS WEST OF THE JAMES
RIVER MOST LIKELY TO SEE READINGS CLIMB WELL ABOVE NORMAL THURSDAY.
CONFIDENCE DECREASES SIGNIFICANTLY IN THE LATTER PART OF THE PERIOD
AS MODELS SHOW MUCH GREATER DIVERGENCE IN HANDLING STRONG SOUTHERN
STREAM TROUGH WHICH DIGS THROUGH THE DESERT SOUTHWEST LATE THIS
WEEK. ECMWF SWINGING A CUTOFF LOW OUT INTO THE CENTRAL PLAINS NEXT
WEEKEND...WITH 04/00Z RUN STRONGER/FARTHER NORTH THAN 03/12Z RUN...
THOUGH BOTH WOULD PRODUCE A PERIOD OF SIGNIFICANT PRECIPITATION
ACROSS THIS AREA AT SOME POINT NEXT WEEKEND. OPERATIONAL GFS...ON
THE OTHER HAND...KICKS ONE PIECE OF ENERGY INTO THE PLAINS FOR
SATURDAY...BUT OTHERWISE HOLDS MAIN UPPER TROUGH OVER THE DESERT
SOUTHWEST WITH LARGELY DRY CONDITIONS FOR THE LATTER HALF OF THE
WEEKEND. GFS ENSEMBLE NOT MUCH HELP AS ITS MEAN IS MORE PROGRESSIVE
BUT MUCH FARTHER SOUTH THAN ECMWF WITH CLOSED LOW KICKING OUT INTO
THE SOUTHERN PLAINS...KEEPING PRIMARY PRECIPITATION THREAT SOUTH OF
THIS AREA. GIVEN THE DISPARITY IN SOLUTIONS AT THIS RANGE...WILL NOT
VARY MUCH OF BROAD MODEL CONSENSUS...WHICH HOLDS ONTO A SMALL CHANCE
OF PRECIP ACROSS OUR SOUTH FRIDAY NIGHT THROUGH SATURDAY NIGHT...
FOLLOWED BY SLIGHTLY GREATER CHANCES SPREADING FARTHER NORTH ACROSS
THE FORECAST AREA ON SUNDAY. TEMPERATURES WILL LIKEWISE BE HELD NEAR
CONSENSUS...WHICH IS GENERALLY ON THE COOL SIDE OF NORMAL WITH HIGHS
IN THE 30S/AROUND 40...BUT VARIANCE IN SOLUTIONS LEADS TO ADDITIONAL
CONCERNS REGARDING PRECIPITATION TYPE...AND WILL KEEP THIS RATHER
GENERIC WITH CHANCE OF RAIN OR SNOW WORDING THROUGHOUT THE PERIOD.
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
LARGELY MVFR STRATUS BEGINNING TO SPREAD BACK ACROSS WESTERN PARTS
OF FORECAST AREA WHILE EASTERN AREAS REMAIN UNDER LINGERING MVFR/IFR
CEILINGS. RAP CONTINUES TO HAVE BEST GRASP ON NEAR TERM MOISTURE AND
PRECIPITATION TRENDS...AND ASIDE FROM NARROW BAND OF SHOWERY PRECIP
RIGHT ALONG A WIND SHIFT LINE ENTERING FAR WESTERN FORECAST AREA
WHICH COULD AFFECT KHON AT THE START OF THE PERIOD...EXPECT LARGELY
DRY FORECAST FOR THE TAF SITES THROUGH THE DAY. HOWEVER...AS THIS
FEATURE TRANSLATES EAST INTO I-29 CORRIDOR...MID LEVEL MOISTURE
BECOMES MORE SCARCE... BUT ENOUGH WEAK LIFT PERSISTS ABOVE STRATUS
DECK THAT WILL KEEP BRIEF PERIOD OF POTENTIAL FREEZING DRIZZLE
AROUND KFSD LATER IN THE MORNING. MID LEVEL MOISTURE INCREASES EAST
OF I-29...BRINGING GREATER CHANCE OF MVFR-OCCASIONAL IFR VISIBILITY
IN -SN TO SOUTHWEST MINNESOTA THIS AFTERNOON. BETTER CHANCE FOR SOME
LIGHT SNOWFALL RETURNS TO TAF SITES AFTER THIS EVENING...AS MOISTURE
WRAPS BACK INTO AREA BEHIND EXITING WAVE. GREATER AVIATION CONCERN
FOR LATTER PART OF THE PERIOD WILL BE INCREASING WINDS BEHIND THE
SYSTEM...ESPECIALLY THROUGH THE JAMES AND WESTERN MISSOURI RIVER
CORRIDOR BY VERY LATE AFTERNOON...EXPANDING EASTWARD IN THE EVENING.
SURFACE WIND GUSTS OF 25 TO 35 KNOTS LIKELY DURING THE LATER EVENING
AND OVERNIGHT.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
SDZ050-052-057>060-063>066-068>071.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR SDZ040-056.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR SDZ039-055-062.
MN...WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR MNZ071-072-
080-081-089-090-097.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ098.
IA...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
IAZ031.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR IAZ002-003-
014.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR IAZ001.
NE...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
NEZ013-014.
&&
$$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
410 AM CST MON MAR 4 2013
.DISCUSSION...ISSUED AT 410 AM CST/
CURRENT SATELLITE AND RADAR VERY EARLY THIS MORNING SHOWING A DRY
SLOT OVERSPREADING OUR AREA WITH THE ONLY RADAR RETURNS BEING
CONFINED TO OUR FAR NORTHEAST FROM MARSHALL TO JACKSON. IN LIGHT OF
THIS...CUT BACK A GOOD BIT ON POPS THROUGH THE MORNING HOURS WITH
PRECIPITATION REDEVELOPMENT PROBABLY NOT OCCURRING UNTIL THE UPPER
LEVEL WAVE PRESENTLY OVER EASTERN MONTANA BEGINS TO DROP
SOUTHEASTWARD...EXERTING INFLUENCE ON OUR AREA BY AFTERNOON. HAVE
HAD SOME VERY LIGHT FREEZING RAIN AND DRIZZLE OVER PORTIONS OF OUR
NORTHERN AND EASTERN AREAS OVERNIGHT...AND WITH STRATUS OOZING INTO
THE AREA FROM THE NORTHWEST CANNOT RULE OUT PATCHY FREEZING DRIZZLE
IN SOME LOCALES DURING THE MORNING. IN LIGHT OF THE ABOVE
TRENDS...READJUSTED CURRENT HEADLINES BY DROPPING THE WESTERN AND
SOUTHERN PORTIONS OF OUR ADVISORY THAT WENT THROUGH 18Z WITH LITTLE
ELSE EXPECTED...BUT KEPT THE ADVISORY OVER OUR NORTHEASTERN CWA
THOUGH EXTENDING IT 6 HOURS...12Z TO 18Z TUESDAY...WITH LIGHT SNOW
PERSISTING OVER THAT AREA INTO THAT TIME FRAME. THE PRECIPITATION
POTENTIAL WILL PICK UP IN OUR EAST BY THIS AFTERNOON INTO THIS
EVENING AS LIFT INCREASES OVER THAT AREA AS THE AFOREMENTIONED UPPER
LEVEL WAVE TRACKS ACROSS THE REGION. TEMPERATURES ALOFT WILL SUPPORT
SNOW BY THAT POINT...THOUGH AREAS ALONG THE WESTERN AND SOUTHERN
FRINGES OF THE PRECIPITATION SHIELD COULD BE MIXED WITH OR BE IN THE
FORM OF PLAIN RAIN WITH SURFACE TEMPERATURES IN THE MID AND UPPER
30S.
THE CRUX OF THE BETTER LIFT WILL BE LOCATED THROUGH OUR NORTHEASTERN
ZONES TONIGHT INTO EARLY ON TUESDAY PER UPPER LEVEL DIV Q
FIELDS...AND THIS IS WHEN MOST OF THE SNOW WILL OCCUR OVER THAT
AREA. STILL LOOKING AT 2 TO 4 INCHES OF ACCUMULATION OVER THE
ADVISORY AREA...GENERALLY IN A LINE FROM BROOKINGS TO SPENCER
EASTWARD. IN ADDITION...NORTHWESTERLY WINDS WILL PICK UP OVERNIGHT
WITH STRONG COLD AIR ADVECTION AND A TIGHTENING GRADIENT ON THE
BACKSIDE OF THE EXITING INVERTED SURFACE TROUGH. THE STRONGEST WINDS
LOOK TO BE ALONG THE MISSOURI RIVER CORRIDOR...AND KEPT THE WIND
ADVISORY...THOUGH EXPANDED SLIGHTLY...FOR THAT AREA STARTING EARLY
TONIGHT AND GOING THROUGH 18Z ON TUESDAY. WITH THE COLD AIR
ADVECTION WE WILL HAVE FALLING TEMPERATURES...THOUGH READINGS WILL
REMAIN IN CHECK WITH THE STRONG WINDS...BOTTOMING OUT IN THE UPPER
TEENS TO LOWER 20S BY EARLY TUESDAY MORNING.
FORCING AND ANY DEEPER MOISTURE PULL AWAY FROM THE AREA ON
TUESDAY...WITH SNOW DIMINISHING IN OUR EAST THROUGH THE MORNING AND
EARLY AFTERNOON HOURS. WITH DECREASING CLOUDS IN THE AFTERNOON UNDER
THE INFLUENCE OF SUBSIDENCE AS HIGH PRESSURE BUILDS INTO OUR WEST.
HIGHS LOOK TO BE IN THE 20S. THE SURFACE RIDGE AXIS SLIDES ACROSS
OUR CWA ON TUESDAY NIGHT...AND WITH DYING WINDS AND CLEARING SKIES
IT WILL BE A COLD NIGHT. LOWS WILL RANGE FROM THE LOWER SINGLE
DIGITS IN OUR NORTHEAST WHERE FRESH SNOW COVER WILL RESIDE...TO JUST
ABOVE 10 ALONG THE MISSOURI RIVER CORRIDOR.
A SOUTHERLY FLOW RETURNS TO THE REGION ON WEDNESDAY AS HIGH PRESSURE
PUSHES OFF TO THE EAST. WITH WARMING THERMAL PROFILES HIGHS WILL
APPROACH 40 IN OUR SOUTH CENTRAL SOUTH DAKOTA ZONES...TAPERING
DOWNWARD TO THE NORTH AND EAST WITH HIGHS ONLY IN THE LOWER 20S IN
OUR SOUTHWESTERN MINNESOTA AREAS WHICH WILL HAVE DEEPER SNOW COVER.
LONG RANGE THURSDAY THROUGH SUNDAY STARTS OFF WITH FAIRLY GOOD
AGREEMENT AMONG THE MODELS...SHOWING LONG WAVE RIDGE IN PLACE ACROSS
THE AREA WITH WEAK NORTHERN STREAM SHORTWAVE TOPPING THE RIDGE NORTH
OF THIS FORECAST AREA. MILD LOW LEVEL AIR IN PLACE WITH 850MB TEMPS
ABOVE 0C THROUGH FRIDAY WILL BRING TEMPERATURES CLOSER TO SEASONAL
NORMALS THAN WE HAVE SEEN OF LATE...WITH AREAS WEST OF THE JAMES
RIVER MOST LIKELY TO SEE READINGS CLIMB WELL ABOVE NORMAL THURSDAY.
CONFIDENCE DECREASES SIGNIFICANTLY IN THE LATTER PART OF THE PERIOD
AS MODELS SHOW MUCH GREATER DIVERGENCE IN HANDLING STRONG SOUTHERN
STREAM TROUGH WHICH DIGS THROUGH THE DESERT SOUTHWEST LATE THIS
WEEK. ECMWF SWINGING A CUTOFF LOW OUT INTO THE CENTRAL PLAINS NEXT
WEEKEND...WITH 04/00Z RUN STRONGER/FARTHER NORTH THAN 03/12Z RUN...
THOUGH BOTH WOULD PRODUCE A PERIOD OF SIGNIFICANT PRECIPITATION
ACROSS THIS AREA AT SOME POINT NEXT WEEKEND. OPERATIONAL GFS...ON
THE OTHER HAND...KICKS ONE PIECE OF ENERGY INTO THE PLAINS FOR
SATURDAY...BUT OTHERWISE HOLDS MAIN UPPER TROUGH OVER THE DESERT
SOUTHWEST WITH LARGELY DRY CONDITIONS FOR THE LATTER HALF OF THE
WEEKEND. GFS ENSEMBLE NOT MUCH HELP AS ITS MEAN IS MORE PROGRESSIVE
BUT MUCH FARTHER SOUTH THAN ECMWF WITH CLOSED LOW KICKING OUT INTO
THE SOUTHERN PLAINS...KEEPING PRIMARY PRECIPITATION THREAT SOUTH OF
THIS AREA. GIVEN THE DISPARITY IN SOLUTIONS AT THIS RANGE...WILL NOT
VARY MUCH OF BROAD MODEL CONSENSUS...WHICH HOLDS ONTO A SMALL CHANCE
OF PRECIP ACROSS OUR SOUTH FRIDAY NIGHT THROUGH SATURDAY NIGHT...
FOLLOWED BY SLIGHTLY GREATER CHANCES SPREADING FARTHER NORTH ACROSS
THE FORECAST AREA ON SUNDAY. TEMPERATURES WILL LIKEWISE BE HELD NEAR
CONSENSUS...WHICH IS GENERALLY ON THE COOL SIDE OF NORMAL WITH HIGHS
IN THE 30S/AROUND 40...BUT VARIANCE IN SOLUTIONS LEADS TO ADDITIONAL
CONCERNS REGARDING PRECIPITATION TYPE...AND WILL KEEP THIS RATHER
GENERIC WITH CHANCE OF RAIN OR SNOW WORDING THROUGHOUT THE PERIOD.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
MODELS AGAIN ARE STRUGGLING MIGHTILY IN DEPICTION OF THE NEAR
SURFACE LAYER...EXHIBITING A VERY STRONG COLD AND HIGH RELATIVE
HUMIDITY BIAS. RAP HAS THE BEST HANDLE ON THIS...AND WOULD SUGGEST
LITTLE PRECIPITATION FOR TAF SITES BEYOND THE IMMEDIATE TERM...AND
THIS TYPE WOULD LIKELY REMAIN LIQUID WITH TEMPS ALOFT FOR TAF
SITES...WITH WET BULB PROCESS TO SNOW IN PRECIPITATION BAND LIFTING
NORTHEAST. AS TEMPERATURES DRY OUT ALOFT TONIGHT BEHIND THE MAIN
BAND...INDICATIONS ARE FOR SOME DEVELOPMENT OF IFR OR LIFR CEILINGS
ALONG WITH DRIZZLE/FREEZING DRIZZLE BY LATER TONIGHT AND INTO MONDAY
MORNING. BRIEF PERIOD WITH SOME MID LEVEL CLOUDINESS AS DIV Q
INCREASES LATER MORNING OR MIDDAY COULD YIELD ICE PROCESS
INTRODUCTION AND THREAT FOR A BRIEF PERIOD OF LIGHT SNOWFALL WITH
MVFR OR IFR VISIBILITY. BETTER THREAT FOR SNOWFALL FOR TAF SITES
LOOKS TO EXIST JUST BEYOND CURRENT FORECAST. WINDS WILL INCREASE
BEHIND THE SYSTEM THROUGH THE JAMES AND WESTERN MISSOURI RIVER
CORRIDOR BY VERY LATE AFTERNOON...EXPANDING EASTWARD IN THE EVENING
BEHIND THE INVERTED TROUGH...WHERE SURFACE WIND GUSTS OF 30 TO 40 KNOTS
LIKELY DURING THE LATER EVENING. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
SDZ050-052-057>060-063>066-068>071.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR SDZ040-056.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR SDZ039-055-062.
MN...WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR MNZ071-072-
080-081-089-090-097.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ098.
IA...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
IAZ031.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR IAZ002-003-
014.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR IAZ001.
NE...WIND ADVISORY FROM 10 PM THIS EVENING TO NOON CST TUESDAY FOR
NEZ013-014.
&&
$$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1109 PM CST SUN MAR 3 2013
.DISCUSSION.../ISSUED AT 651 PM CST/
LIGHT PRECIPITATION OR DRIZZLE HAS DEVELOPED ALONG THE ISENTROPIC
LIFT ACROSS THE NORTHEASTERN HALF OF THE FORECAST AREA THIS EVENING.
TEMPERATURES REMAIN RELATIVELY MILD WITH THE VAST MAJORITY OF OBS
STILL AT OR ABOVE FREEZING. MODELS HAVING QUITE A BIT OF DIFFICULTY
WITH THIS SYSTEM ESPECIALLY AT THE NEAR SURFACE. MUCH OF THE AREA
REMAINS QUITE DRY AT THE LOWER LEVELS WHICH IS NOT WELL HANDLED BY
ANY MODEL EXCEPT PERHAPS THE RAP. WITH THE LACK OF LOW LEVEL
MOISTURE AND THE MILDER SURFACE TEMPERATURES...PRECIPITATION HAS
BEEN VERY LIGHT OR DRIZZLY FOR THE MOST PART. THE HRRR AND RAP
SUGGEST THAT THE ISENTROPIC BAND WILL LIKELY LIFT NORTHEAST INTO THE
EARLY MORNING HOURS...KEEPING THE MORE ORGANIZED PRECIPITATION...AND
SNOWFALL POTENTIAL MAINLY ALONG AND EAST OF A BROOKINGS TO SPENCER
LINE OVERNIGHT. ELSEWHERE...VERY LIGHT RAIN...FREEZING RAIN OR
DRIZZLE IS EXPECTED INTO THE EARLY MORNING HOURS. IF WE CANNOT GET
MORE SIGNIFICANT LOW LEVEL MOISTURE/CLOUDS TO DEVELOP
OVERNIGHT...THE VAST MAJORITY OF THE CWA WILL SEE NO SNOW
DEVELOPMENT.
MADE SOME CHANGES MAINLY TO THE POPS AND PRECIPITATION TYPES. HAVE
DROPPED OFF THE POTENTIAL FOR MEASURABLE PRECIPITATION TO CHANCES OR
SLIGHT CHANGES AFTER MIDNIGHT FOR ALL BUT OUR FAR NORTHEASTERN
COUNTIES...WHICH IS CLOSER IN LINE WITH THE HRRR...RAP AND NAM.
PRECIPITATION TYPES WERE ADJUSTED TO KEEP IN LINE WITH THE WARMER
SURFACE AND LOW LEVEL TEMPERATURES. FOR AREAS OUTSIDE OF THE MORE
ORGANIZED ISENTROPIC LIFT ZONE...NEAR SOUTHWEST MINNESOTA...HAVE
LOWERED QPF...ICE ACCUMULATIONS AND SNOW AMOUNTS WITH MORE DRIZZLY
CONDITIONS BEING REPORTED. ALSO WARMED LOWS A BIT WITH MID AND HIGH
CLOUDS STICKING AROUND TONIGHT AND THE SOMEWHAT BREEZY SOUTHEAST
WINDS HOLDING ON THROUGH THE BULK OF THE NIGHT.
THE WINTER WEATHER ADVISORY REMAINS AS IS...BUT WILL BE REVISITING
THINGS LATER THIS EVENING. MAY POTENTIALLY NEED TO DROP SOME OF THE
WESTERN COUNTIES IF WE DO NOT SEE PRECIPITATION RATES OR LOW LEVEL
MOISTURE INCREASE THROUGH THE NEXT FEW HOURS.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
MODELS AGAIN ARE STRUGGLING MIGHTILY IN DEPICTION OF THE NEAR
SURFACE LAYER...EXHIBITING A VERY STRONG COLD AND HIGH RELATIVE
HUMIDITY BIAS. RAP HAS THE BEST HANDLE ON THIS...AND WOULD SUGGEST
LITTLE PRECIPITATION FOR TAF SITES BEYOND THE IMMEDIATE TERM...AND
THIS TYPE WOULD LIKELY REMAIN LIQUID WITH TEMPS ALOFT FOR TAF
SITES...WITH WET BULB PROCESS TO SNOW IN PRECIPITATION BAND LIFTING
NORTHEAST. AS TEMPERATURES DRY OUT ALOFT TONIGHT BEHIND THE MAIN
BAND...INDICATIONS ARE FOR SOME DEVELOPMENT OF IFR OR LIFR CEILINGS
ALONG WITH DRIZZLE/FREEZING DRIZZLE BY LATER TONIGHT AND INTO MONDAY
MORNING. BRIEF PERIOD WITH SOME MID LEVEL CLOUDINESS AS DIV Q
INCREASES LATER MORNING OR MIDDAY COULD YIELD ICE PROCESS
INTRODUCTION AND THREAT FOR A BRIEF PERIOD OF LIGHT SNOWFALL WITH
MVFR OR IFR VISIBILITY. BETTER THREAT FOR SNOWFALL FOR TAF SITES
LOOKS TO EXIST JUST BEYOND CURRENT FORECAST. WINDS WILL INCREASE
BEHIND THE SYSTEM THROUGH THE JAMES AND WESTERN MISSOURI RIVER
CORRIDOR BY VERY LATE AFTERNOON...EXPANDING EASTWARD IN THE EVENING
BEHIND THE INVERTED TROUGH...WHERE SURFACE WIND GUSTS OF 30 TO 40 KNOTS
LIKELY DURING THE LATER EVENING. /CHAPMAN
&&
.PREV DISCUSSION.../ISSUED AT 302 PM CST/
ISENTROPIC LIFT ON THE 290 AND 295K SURFACES INCREASING RESULTING IN
SOME LIGHT RAIN ALONG A BAND FROM KHON-KFSD. AS ISENTROPIC LIFT
CONTINUES TO INCREASE...EXPECT BAND TO BECOME MORE ESTABLISHED INTO
THE EVENING HOURS. WARM YET DRY LAYER ALOFT NEAR 850 MB. AS
PRECIPITATION INTENSITY INCREASES...EXPECT LAYER TO EVAPORATIVELY
COOL LEADING TO THE POTENTIAL OF SNOW...HOWEVER...UPPER LEVELS BEGIN
TO DRY OUT FROM THE SOUTHWEST TO THE NORTHEAST MAKING IT DIFFICULT
TO GET ICE INTO THE COLUMN. FOR THIS EVENING...POTENTIAL FOR SOME
LIGHT RAIN/FREEZING RAIN ACROSS MUCH OF THE CWA. HAVE ISSUED WINTER
WEATHER ADVISORY FOR AREAS WHERE THERE IS A HIGHER CONFIDENCE FOR
LIGHT ICING POTENTIAL. WESTERN EDGE OF THE ADVISORY WAS DIFFICULT TO
DETERMINE...AND MAY NEED TO BE EXPANDED IF ICING BECOMES MORE
WIDESPREAD. ACROSS NORTHEAST CORNER OF FORECAST AREA...MAY SEE RAIN
CHANGE OVER TO SNOW THROUGH THE EVENING HOURS WITH A FEW INCHES OF
ACCUMULATION BEFORE THE ISENTROPIC LIFT DIES AWAY FROM WEST TO EAST
FROM 06-12Z MONDAY. MODELS INDICATE FAIR AMOUNT OF LOW LEVEL
SATURATION...AND MAY BE ABLE TO GET FREEZING DRIZZLE/DRIZZLE THROUGH
THE MORNING HOURS.
MAIN UPPER LEVEL WAVE APPROACHES FROM THE WEST NORTHWEST TOMORROW
AFTERNOON. WITH THE APPROACHING MAIN UPPER LEVEL WAVE...LIFT ONCE
AGAIN INCREASES ESPECIALLY ACROSS THE EASTERN HALF OF THE FORECAST
AREA. FAIRLY SHARP BACK EDGE SHOULD DEVELOP BETWEEN AREAS THAT ARE
ABLE TO SATURATE ALOFT AND THOSE THAT DO NOT. EXPECT BAND OF
PRECIPITATION TO GRADUALLY SHIFT EAST THROUGH THE EVENING
HOURS...WITH WINDS INCREASING BEHIND THE COLD FRONT.
MONDAY NIGHT WILL SEE THE SYSTEM WRAP UP AND DROP THROUGH SOUTHWEST
MINNESOTA. WILL KEEP SOME FAIRLY HIGH POPS IN FOR THE NIGHT OVER THE
EASTERN THIRD OF THE CWA. BEST SNOWFALL SHOULD BE NORTH AND EAST OF
A BROOKINGS TO SPENCER IOWA LINE WHERE AN ADDITIONAL 1 TO 3 INCHES
WILL BE POSSIBLE. COLD AIR ALOFT SHOULD ELIMINATE ANY POTENTIAL FOR
MIXED PRECIPITATION AND THINKING ALL SNOW AT THIS POINT. THE OTHER
CONCERN ON MONDAY NIGHT WILL BE THE STRONG NORTHWEST WIND THAT
DEVELOPS. THE MODELS ARE IN PRETTY GOOD AGREEMENT SWINGING THROUGH
ABOUT 35 KNOTS TO 40 KNOTS AT 925MB ALONG WITH GOOD COLD AIR
ADVECTION SO WIND ADVISORY CRITERIA WILL LIKELY BE MET...ESPECIALLY
WEST OF INTERSTATE 29...MONDAY NIGHT INTO TUESDAY MORNING. WILL PUT
AN ADVISORY DOWN THE MISSOURI RIVER VALLEY CORRIDOR.
THE SNOW SHOULD BE WINDING DOWN TUESDAY MORNING WITH THE STRONG
NORTHWEST WINDS DEVELOPING ACROSS THE AREA. MAY BE SOME AREAS OF
BLOWING SNOW IN LOCATIONS THAT RECEIVE ENOUGH SNOWFALL...MAINLY
SOUTHWEST MINNESOTA. WITH SOME SNOW ON THE GROUND AND WINDY
CONDITIONS WILL WILL BE PRETTY COLD WITH HIGHS MAINLY IN THE LOWER
TO MIDDLE 20S...CLOSER TO 30 ALONG THE MISSOURI RIVER VALLEY WHERE
LITTLE TO NO SNOW IS EXPECTED.
TUESDAY NIGHT INTO WEDNESDAY HIGH PRESSURE WILL BUILD SOUTH INTO THE
AREA THEN SHIFT EAST WITH BREEZY CONDITIONS LIKELY WEDNESDAY
AFTERNOON IN CENTRAL SOUTH DAKOTA. LOWS IN THE MORNING WILL DROP
CLOSE TO ZERO ALONG THE HIGHWAY 14 CORRIDOR INTO SOUTHWEST MINNESOTA
WHILE CENTRAL SOUTH DAKOTA WILL BOTTOM OUT IN THE TEENS. HIGHS ON
WEDNESDAY WILL MODERATE BUT STILL 20 TO 25 IN SOUTHWEST MINNESOTA
AND AROUND 40 IN SOUTH CENTRAL SOUTH DAKOTA.
IN THE LATTER PERIODS(THU/SUN)...OVERALL FAIRLY MILD THROUGH THE
PERIOD AS A TROUGH OF LOW PRESSURE BUILDS OVER THE WESTERN UNITED
STATES. THIS WILL SPREAD A RIDGE OF HIGH PRESSURE ACROSS THE CENTRAL
UNITED STATES. THE MODELS CONTINUE TO SLOW THE PROGRESSION OF THIS
TROUGH AND HAVE VERY LITTLE CONSISTENCY SO NO REAL CONFIDENCE JUST
YET. REGARDLESS...ABOVE NORMAL TEMPERATURES MOST LOCATIONS THAT DO
NOT RECEIVE MUCH NEW SNOW WITH NORMAL TO A BIT BELOW NORMAL IN AREAS
WITH DEEPER SNOWCOVER. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON CST
MONDAY FOR SDZ038-039-053>055-061-062-066-067-071.
WIND ADVISORY FROM 10 PM MONDAY TO NOON CST TUESDAY FOR SDZ050-
052-057>060-063>065-068>071.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
TUESDAY FOR SDZ040-056.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON CST
MONDAY FOR MNZ098.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
TUESDAY FOR MNZ071-072-080-081-089-090-097.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON CST
MONDAY FOR IAZ001-012-013-020>022-031-032.
WIND ADVISORY FROM 10 PM MONDAY TO NOON CST TUESDAY FOR IAZ031.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
TUESDAY FOR IAZ002-003-014.
NE...WIND ADVISORY FROM 10 PM MONDAY TO NOON CST TUESDAY FOR NEZ013-
014.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1154 AM CST MON MAR 4 2013
.SHORT TERM...TODAY THROUGH WEDNESDAY
343 AM CST MON MAR 4 2013
FORECAST FOCUS REMAINS ON WINTER STORM IMPACTING THE REGION TODAY
THROUGH TUESDAY.
LATEST WATER VAPOR IMAGERY AND RAP 500 MB ANALYSIS SHOWED A POTENT
LOW CENTERED OVER WESTERN MONTANA. A LEADING SHORTWAVE WAS MOVING
EAST ACROSS WESTERN MINNESOTA/IOWA. A BAND OF LIGHT SNOW EXTENDED
FROM WEST CENTRAL MINNESOTA...SOUTHEAST THROUGH SOUTHEAST
MINNESOTA INTO EASTERN IOWA. VISIBILITIES WITHIN THIS BAND HAD
FALLEN INTO THE 1 TO 2 MILE RANGE.
THE ONGOING BAND OF SNOW WILL CONTINUE MOVING EAST/NORTHEAST THIS
MORNING ACROSS NORTHEAST IOWA AND SOUTHEAST MINNESOTA...APPROACHING
THE MISSISSIPPI RIVER DURING THE MID TO LATE MORNING HOURS.
MESOSCALE MODELS SHOW THE BAND REALLY FALLING APART AS IT MOVES
INTO WESTERN WISCONSIN LATE THIS MORNING INTO EARLY THIS AFTERNOON
AND REALLY NOT MAKING IT TO THE INTERSTATE 94 CORRIDOR AS IT
ENCOUNTERS VERY DRY AIR. KEAU FORECAST SOUNDINGS SHOW THE DRY AIR
EXTENDING FROM THE SURFACE THROUGH AROUND 5KFT...SO IT WILL TAKE
SOME TIME FOR SATURATION TO OCCUR. SNOW ACCUMULATIONS TODAY WILL
BE ON THE LIGHT SIDE RANGING FROM 1 TO POSSIBLY 3 INCHES OVER
SOUTHEAST MINNESOTA INTO NORTHEAST IOWA TO AROUND AN INCH OVER FAR
WESTERN WISCONSIN. FRONTOGENESIS INCREASES...IN THE 850-700 MB
LAYER...THIS AFTERNOON RIGHT ALONG THE MISSISSIPPI RIVER. THIS
COULD KEEP LIGHT SNOWFALL INTO THE EARLY AFTERNOON HOURS BEFORE IT
WANES. GFS FORECAST SOUNDINGS THIS AFTERNOON OVER SOUTHEAST
MINNESOTA....NORTHEAST IOWA...AND FAR SOUTHWEST WISCONSIN SHOW A
LOSS OF ICE ALOFT WHICH COULD LEAD TO SOME FREEZING DRIZZLE. THE
NAM ON THE OTHER HAND KEEPS THE ICE ALOFT ACROSS THESE AREAS.
GIVEN THE CONSISTENT SIGNAL FOR A LOSS OF ICE IN THE GFS WILL
INTRODUCE A SLIGHT CHANCE OF FREEZING DRIZZLE ACROSS THESE AREAS
THIS AFTERNOON INTO EARLY THIS EVENING.
THE LOW WILL DIVE SOUTHEAST TONIGHT INTO THE UPPER MISSISSIPPI RIVER
VALLEY. VERY IMPRESSIVE LARGE SCALE FORCING ASSOCIATED WITH THE LOW
WITH DEEP QG FORCING NOTED PARTICULARLY IN THE 700-500 MB LAYER. A
BROAD AREA OF ISENTROPIC LIFT...MAINLY FOCUSED ON THE 280-310 K
SURFACES...WILL DEVELOP ACROSS THE FORECAST AREA THIS EVENING AND
CONTINUE THROUGH THE OVERNIGHT HOURS. SREF PROBABILITIES FOR SNOWFALL
RATES OF AN INCH PER HOUR DEVELOP ACROSS MOST OF THE FORECAST AREA
THIS EVENING AND CONTINUE THROUGH THE OVERNIGHT HOURS INTO TUESDAY
MORNING. OVERALL FORECAST MODELS ARE IN CLOSE AGREEMENT THIS CYCLE
PLACING A BROAD SWATH OF HEAVY SNOW ACROSS MUCH OF THE AREA WITH
ACCUMULATIONS RANGING FROM 8 TO 13 INCHES. THE HIGHEST
ACCUMULATIONS WILL BE ALONG THE MISSISSIPPI RIVER...AND INCLUDING
ALL OF SOUTHWEST WISCONSIN. DECIDED TO ISSUE A WINTER STORM
WARNING FOR CENTRAL AND NORTH CENTRAL WISCONSIN STARTING AT 6 PM
THIS EVENING AND CONTINUING THROUGH 6 PM TUESDAY. WILL CONTINUE
THE WINTER STORM WARNING FOR THE REST OF THE FORECAST AREA...BUT
PLAN ON THE BULK OF THE ACCUMULATING SNOW TO OCCUR TONIGHT THROUGH
TUESDAY MORNING. GIVEN THE FORCING OVERNIGHT INTO TUESDAY
MORNING...THE SNOW WILL BE HEAVY AT TIMES ESPECIALLY FOR THE
TUESDAY MORNING COMMUTE. THE SNOW IS EXPECTED TO TAPER OFF FROM
NORTHWEST TO SOUTHEAST LATE TUESDAY AFTERNOON AND FINALLY EXIT THE
AREA TUESDAY NIGHT. THE PRESSURE GRADIENT TIGHTENS ACROSS THE AREA
TUESDAY AFTERNOON INTO TUESDAY EVENING WITH NORTH WINDS INCREASING
TO 10 TO 17 MPH WITH GUSTS AROUND 25 MPH POSSIBLE. WILL HAVE TO
KEEP A CLOSE WATCH ON THE POTENTIAL FOR BLOWING SNOW. ALSO...LOW
TEMPERATURES TUESDAY NIGHT COULD BE CHALLENGING WITH THE FRESH
SNOW PACK AND DECREASING CLOUDS. IF CLOUDS CLEAR EARLIER THAN
FORECAST LOWS COULD BE SEVERAL DEGREES COLDER.
HIGH PRESSURE IS EXPECTED TO BUILD INTO THE REGION ON WEDNESDAY AS
RIDGING INTENSIFIES OVER THE CENTRAL CONUS. PLAN ON PARTLY TO MOSTLY
SUNNY SKIES AND SLIGHTLY BELOW NORMAL TEMPERATURES WITH HIGHS RANGING
FROM THE LOWER 30S OVER NORTHERN WISCONSIN TO THE MID 20S ACROSS
SOUTHEAST MINNESOTA.
.LONG TERM...THURSDAY THROUGH SUNDAY
343 AM CST MON MAR 4 2013
04.00 MEDIUM RANGE MODELS ARE IN AGREEMENT THURSDAY INTO FRIDAY
SHOWING RIDGING OVER THE UPPER MIDWEST. A SHORTWAVE LOOKS TO PASS
JUST NORTH OF THE AREA ACROSS NORTHERN MINNESOTA THROUGH SOUTHERN
ONTARIO. THIS FEATURE WILL BRING A SLIGHT CHANCE OF SNOW TO FAR
NORTHERN WISCONSIN AS IT MOVES THROUGH THURSDAY NIGHT. MODEL
SOLUTIONS START TO DIVERGE LATE FRIDAY THROUGH THE WEEKEND WITH THE
HANDLING OF AN UPPER LOW OVER THE DESERT SOUTHWEST. THE ECMWF TAKES
THE LOW INTO THE PLAINS ON SATURDAY...LIFTING INTO THE UPPER
MISSISSIPPI RIVER VALLEY SUNDAY INTO MONDAY. THE GFS KEEPS A CUTOFF
LOW OVER THE SOUTHWEST AND BRINGS AN OPEN WAVE ACROSS THE REGION.
GIVEN THE MODEL DIFFERENCES WILL LEAN TOWARD A MODEL CONSENSUS BLEND
THROUGH THE WEEKEND WITH PRECIPITATION CHANCES FRIDAY NIGHT THROUGH
SUNDAY. WILL HAVE TO KEEP A CLOSE WATCH ON THE NEXT FEW FORECAST
MODEL RUNS SINCE THE SOUTHWEST LOW HAS THE POTENTIAL TO BRING RAIN
AND MUCH WARMER TEMPERATURES TO THE AREA. THE ECMWF WARMS
TEMPERATURES INTO THE 50S ON MONDAY AND BRINGS NEARLY 1/2 INCH OF
RAIN INTO THE AREA. THROUGH THE WEEKEND...PLAN ON TEMPERATURES NEAR
TO SLIGHTLY ABOVE NORMAL WITH HIGHS IN THE UPPER 30S TO AROUND 40.
&&
.AVIATION...THROUGH 18Z TUESDAY
1153 AM CST MON MAR 4 2013
A WEAKENING SNOW BAND WILL MOVE OUT OF KRST BY 04.19Z. IN THIS BAND...
THE CEILINGS ARE IN THE 1500-2500 FOOT RANGE. OUTSIDE OF THIS
BAND...CEILINGS WILL RANGE FROM 3500 TO 5000 FEET.
ANOTHER MORE SIGNIFICANT AREA OF SNOW WILL MOVE INTO SOUTHEAST
MINNESOTA AND NORTHEAST IOWA THIS EVENING...AND THEN OVERSPREAD
THE ENTIRE AREA TONIGHT. THE SNOW WILL THEN CONTINUE INTO TUESDAY.
THE SNOW WILL MOVE INTO KRST BETWEEN 05.00Z AND 05.02Z...AND KLSE
BETWEEN 05.03Z AND 05.05Z. THE HEAVIEST SNOW...POSSIBLY AN INCH
AN HOUR...WILL OCCUR BETWEEN 05.09Z AND 05.18Z. ONCE THE SNOW
BEGINS CEILINGS AND VISIBILITIES WILL BECOME IFR TO MVFR. SNOW
TOTALS AT BOTH TAF SITES WILL RANGE FROM 10 TO 12 INCHES BY 06.00Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
343 PM CST SUN MAR 3 2013
WI...WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
WIZ032-033-041-053>055-061.
WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY
AFTERNOON FOR WIZ017-029-034-042>044.
MN...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR MNZ079-086-087-094-095.
WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
MNZ088-096.
IA...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR IAZ008-009-018-019.
WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
IAZ010-011-029-030.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
547 AM CST MON MAR 4 2013
.SHORT TERM...TODAY THROUGH WEDNESDAY
343 AM CST MON MAR 4 2013
FORECAST FOCUS REMAINS ON WINTER STORM IMPACTING THE REGION TODAY
THROUGH TUESDAY.
LATEST WATER VAPOR IMAGERY AND RAP 500 MB ANALYSIS SHOWED A POTENT
LOW CENTERED OVER WESTERN MONTANA. A LEADING SHORTWAVE WAS MOVING
EAST ACROSS WESTERN MINNESOTA/IOWA. A BAND OF LIGHT SNOW EXTENDED
FROM WEST CENTRAL MINNESOTA...SOUTHEAST THROUGH SOUTHEAST
MINNESOTA INTO EASTERN IOWA. VISIBILITIES WITHIN THIS BAND HAD
FALLEN INTO THE 1 TO 2 MILE RANGE.
THE ONGOING BAND OF SNOW WILL CONTINUE MOVING EAST/NORTHEAST THIS
MORNING ACROSS NORTHEAST IOWA AND SOUTHEAST MINNESOTA...APPROACHING
THE MISSISSIPPI RIVER DURING THE MID TO LATE MORNING HOURS.
MESOSCALE MODELS SHOW THE BAND REALLY FALLING APART AS IT MOVES
INTO WESTERN WISCONSIN LATE THIS MORNING INTO EARLY THIS AFTERNOON
AND REALLY NOT MAKING IT TO THE INTERSTATE 94 CORRIDOR AS IT
ENCOUNTERS VERY DRY AIR. KEAU FORECAST SOUNDINGS SHOW THE DRY AIR
EXTENDING FROM THE SURFACE THROUGH AROUND 5KFT...SO IT WILL TAKE
SOME TIME FOR SATURATION TO OCCUR. SNOW ACCUMULATIONS TODAY WILL
BE ON THE LIGHT SIDE RANGING FROM 1 TO POSSIBLY 3 INCHES OVER
SOUTHEAST MINNESOTA INTO NORTHEAST IOWA TO AROUND AN INCH OVER FAR
WESTERN WISCONSIN. FRONTOGENESIS INCREASES...IN THE 850-700 MB
LAYER...THIS AFTERNOON RIGHT ALONG THE MISSISSIPPI RIVER. THIS
COULD KEEP LIGHT SNOWFALL INTO THE EARLY AFTERNOON HOURS BEFORE IT
WANES. GFS FORECAST SOUNDINGS THIS AFTERNOON OVER SOUTHEAST
MINNESOTA....NORTHEAST IOWA...AND FAR SOUTHWEST WISCONSIN SHOW A
LOSS OF ICE ALOFT WHICH COULD LEAD TO SOME FREEZING DRIZZLE. THE
NAM ON THE OTHER HAND KEEPS THE ICE ALOFT ACROSS THESE AREAS.
GIVEN THE CONSISTENT SIGNAL FOR A LOSS OF ICE IN THE GFS WILL
INTRODUCE A SLIGHT CHANCE OF FREEZING DRIZZLE ACROSS THESE AREAS
THIS AFTERNOON INTO EARLY THIS EVENING.
THE LOW WILL DIVE SOUTHEAST TONIGHT INTO THE UPPER MISSISSIPPI RIVER
VALLEY. VERY IMPRESSIVE LARGE SCALE FORCING ASSOCIATED WITH THE LOW
WITH DEEP QG FORCING NOTED PARTICULARLY IN THE 700-500 MB LAYER. A
BROAD AREA OF ISENTROPIC LIFT...MAINLY FOCUSED ON THE 280-310 K
SURFACES...WILL DEVELOP ACROSS THE FORECAST AREA THIS EVENING AND
CONTINUE THROUGH THE OVERNIGHT HOURS. SREF PROBABILITIES FOR SNOWFALL
RATES OF AN INCH PER HOUR DEVELOP ACROSS MOST OF THE FORECAST AREA
THIS EVENING AND CONTINUE THROUGH THE OVERNIGHT HOURS INTO TUESDAY
MORNING. OVERALL FORECAST MODELS ARE IN CLOSE AGREEMENT THIS CYCLE
PLACING A BROAD SWATH OF HEAVY SNOW ACROSS MUCH OF THE AREA WITH
ACCUMULATIONS RANGING FROM 8 TO 13 INCHES. THE HIGHEST
ACCUMULATIONS WILL BE ALONG THE MISSISSIPPI RIVER...AND INCLUDING
ALL OF SOUTHWEST WISCONSIN. DECIDED TO ISSUE A WINTER STORM
WARNING FOR CENTRAL AND NORTH CENTRAL WISCONSIN STARTING AT 6 PM
THIS EVENING AND CONTINUING THROUGH 6 PM TUESDAY. WILL CONTINUE
THE WINTER STORM WARNING FOR THE REST OF THE FORECAST AREA...BUT
PLAN ON THE BULK OF THE ACCUMULATING SNOW TO OCCUR TONIGHT THROUGH
TUESDAY MORNING. GIVEN THE FORCING OVERNIGHT INTO TUESDAY
MORNING...THE SNOW WILL BE HEAVY AT TIMES ESPECIALLY FOR THE
TUESDAY MORNING COMMUTE. THE SNOW IS EXPECTED TO TAPER OFF FROM
NORTHWEST TO SOUTHEAST LATE TUESDAY AFTERNOON AND FINALLY EXIT THE
AREA TUESDAY NIGHT. THE PRESSURE GRADIENT TIGHTENS ACROSS THE AREA
TUESDAY AFTERNOON INTO TUESDAY EVENING WITH NORTH WINDS INCREASING
TO 10 TO 17 MPH WITH GUSTS AROUND 25 MPH POSSIBLE. WILL HAVE TO
KEEP A CLOSE WATCH ON THE POTENTIAL FOR BLOWING SNOW. ALSO...LOW
TEMPERATURES TUESDAY NIGHT COULD BE CHALLENGING WITH THE FRESH
SNOW PACK AND DECREASING CLOUDS. IF CLOUDS CLEAR EARLIER THAN
FORECAST LOWS COULD BE SEVERAL DEGREES COLDER.
HIGH PRESSURE IS EXPECTED TO BUILD INTO THE REGION ON WEDNESDAY AS
RIDGING INTENSIFIES OVER THE CENTRAL CONUS. PLAN ON PARTLY TO MOSTLY
SUNNY SKIES AND SLIGHTLY BELOW NORMAL TEMPERATURES WITH HIGHS RANGING
FROM THE LOWER 30S OVER NORTHERN WISCONSIN TO THE MID 20S ACROSS
SOUTHEAST MINNESOTA.
.LONG TERM...THURSDAY THROUGH SUNDAY
343 AM CST MON MAR 4 2013
04.00 MEDIUM RANGE MODELS ARE IN AGREEMENT THURSDAY INTO FRIDAY
SHOWING RIDGING OVER THE UPPER MIDWEST. A SHORTWAVE LOOKS TO PASS
JUST NORTH OF THE AREA ACROSS NORTHERN MINNESOTA THROUGH SOUTHERN
ONTARIO. THIS FEATURE WILL BRING A SLIGHT CHANCE OF SNOW TO FAR
NORTHERN WISCONSIN AS IT MOVES THROUGH THURSDAY NIGHT. MODEL
SOLUTIONS START TO DIVERGE LATE FRIDAY THROUGH THE WEEKEND WITH THE
HANDLING OF AN UPPER LOW OVER THE DESERT SOUTHWEST. THE ECMWF TAKES
THE LOW INTO THE PLAINS ON SATURDAY...LIFTING INTO THE UPPER
MISSISSIPPI RIVER VALLEY SUNDAY INTO MONDAY. THE GFS KEEPS A CUTOFF
LOW OVER THE SOUTHWEST AND BRINGS AN OPEN WAVE ACROSS THE REGION.
GIVEN THE MODEL DIFFERENCES WILL LEAN TOWARD A MODEL CONSENSUS BLEND
THROUGH THE WEEKEND WITH PRECIPITATION CHANCES FRIDAY NIGHT THROUGH
SUNDAY. WILL HAVE TO KEEP A CLOSE WATCH ON THE NEXT FEW FORECAST
MODEL RUNS SINCE THE SOUTHWEST LOW HAS THE POTENTIAL TO BRING RAIN
AND MUCH WARMER TEMPERATURES TO THE AREA. THE ECMWF WARMS
TEMPERATURES INTO THE 50S ON MONDAY AND BRINGS NEARLY 1/2 INCH OF
RAIN INTO THE AREA. THROUGH THE WEEKEND...PLAN ON TEMPERATURES NEAR
TO SLIGHTLY ABOVE NORMAL WITH HIGHS IN THE UPPER 30S TO AROUND 40.
&&
.AVIATION...TODAY AND TONIGHT
547 AM CST MON MAR 4 2013
SNOW HAS MOVED INTO KRST WITH VISIBILITIES RAPIDLY DROPPING TO
IFR. CEILINGS HAVE ALSO DROPPED QUICKLY TO MVFR. FARTHER TO THE
EAST...DRY AIR CONTINUES TO HOLD STRONG AT KLSE WITH VFR
CONDITIONS IN PLACE.
FOR TODAY...THE BACK EDGE OF THE SNOW WAS JUST TO THE WEST OF
KAEL AS OF 1130Z. THIS SHOULD REACH KRST BY 16Z...ALLOWING
VISIBILITIES TO COME UP TO MVFR OR EVEN VFR. HOWEVER...CEILINGS
ARE GOING TO CONTINUE TO DROP...LIKELY TO IFR BY 16Z. AS THE SNOW
DIMINISHES...SOME FREEZING DRIZZLE MAY OCCUR FOR THE AFTERNOON.
MEANWHILE AT KLSE...DRY AIR SHOULD HOLD THE BAND OF SNOW OFF FOR A
FEW MORE HOURS. AROUND 16Z...ANTICIPATING THE SNOW TO MOVE
IN...THOUGH IT SHOULD BE WEAKER DUE TO THE DRY AIR COMPARED TO
WHAT HAPPENED AT KRST. STILL HAVE VISIBILITIES DROPPING TO
IFR...BUT CEILINGS WILL TAKE A LOT LONGER TO LOWER...ONLY DROPPING
TO MVFR. TOTAL SNOW ACCUMULATIONS TODAY ARE EXPECTED AROUND 2
INCHES AT KRST AND UP TO 1 INCH AT KLSE.
FOR TONIGHT...HEAVIER SNOW IS EXPECTED TO DEVELOP AT BOTH TAF
SITES AS A LOW PRESSURE AREA DROPS SOUTHEAST OUT OF THE DAKOTAS.
VISIBILITIES SHOULD LOWER TO IFR DURING THE EVENING...THEN TO LIFR
OVERNIGHT. CEILINGS ARE ALSO EXPECTED TO LOWER...TO LIFR AT KRST
AND IFR AT KLSE DURING THE EVENING HOURS. PLAN ON TOTAL SNOW
ACCUMULATIONS OF 5 TO 6 INCHES AT BOTH TAF SITES.
LOOKING AHEAD TO TUESDAY...THE HEAVY SNOW MOVING IN TONIGHT LOOKS
TO PERSIST THROUGH THE MORNING HOURS. THEREFORE...DIFFICULT
AVIATION TRAVEL IS ANTICIPATED. WINDS ALSO PICK UP DURING THE
AFTERNOON...ADDING BLOWING SNOW INTO THE MIX. AN ADDITIONAL 4 TO 6
INCHES IS POSSIBLE AT BOTH TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
343 PM CST SUN MAR 3 2013
WI...WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
WIZ032-033-041-053>055-061.
WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY
AFTERNOON FOR WIZ017-029-034-042>044.
MN...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR MNZ079-086-087-094-095.
WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
MNZ088-096.
IA...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR IAZ008-009-018-019.
WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
IAZ010-011-029-030.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
359 AM CST MON MAR 4 2013
.SHORT TERM...
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM TO HIGH
ALL MODELS INDICATE BEGINNING OF SNOW WITH INITIAL WAA
BAND...CURRENTLY PRODUCING 1 TO 2 MILE SNOW IN A BAND FROM SW MN
INTO CENTRAL IOWA...WILL BE DELAYED AND LIGHTER THAN EXPECTED AS IT
RUNS INTO DRY AIR BELOW 5K FT ON CROSS SECTIONS AND 500 MB RIDGE
AMPLIFYING OVER REGION IN RESPONSE TO THE DEEPENING TROUGH AS IT
DROPS INTO THE NRN PLAINS. HRRR IS ESPECIALLY MEAGER...WIPING OUT
THIS INITIAL BAND BEFORE IT GETS TO CWA. RAP AND WRF-CORE MODELS
ALSO WEAKEN THIS INITIAL BAND.
ISENTROPIC FORECASTS INDICATE IT WILL TAKE A BIT LONGER TO SATURATE
THE LOWER LAYERS...WITH ALL MODELS/SAVE THE GFS/ HOLDING PCPN TO THE
WEST OF MADISON THRU 00Z TUE. LOOKING FOR UNDER 1/2 INCH IN THE FAR
WEST THIS MORNING...WITH 1/2 INCH OR LESS FROM MADISON AND WEST BY
00Z TUE. WE DO LOSE MOISTURE IN DENDRITE GROWTH ZONE ON THE GFS
BUFKIT SOUNDINGS IN THE LULL BETWEEN THE INITIAL WEAKENING WAA BAND
AND THE STEADIER SNOW WITH THE SYSTEM DYNAMICS THAT MOVES IN AFTER
00Z TUESDAY...BUT WITH WARMEST TEMP IN COLUMN AT -3C AND WET BULB
BELOW 0C...TOP-DOWN SUGGESTS LIGHT SNOW OR MAYBE SNOW PELLETS VERSUS
FREEZING DRIZZLE.
SNOW WILL INCREASE IN COVERAGE AND INTENSITY AS STRONGER FORCING
MOVES INTO THE REGION AFTER 00Z. WILL TRACK THE INCREASING SNOW FROM
SW TO NE WITH ISENTROPIC LIFT AND STRONGER LAYER Q-VECTOR
CONVERGENCE. THIS KEEPS THE FAR NE OUT OF THE BETTER SNOW UNTIL 12Z
TUE OR LATER.
TUESDAY AND TUESDAY NIGHT...FORECAST CONFIDENCE MEDIUM
THE CLOSED UPPER LOW OVER THE DAKOTAS WILL DIG DOWN INTO IOWA AND
ABSORB A SOUTHERN STREAM SHORTWAVE AROUND 12Z-18Z TUE. THE SURFACE
LOW OVER SOUTHERN IL WILL DEEPEN AND AN INVERTED TROUGH WILL EXTEND
NORTHWEST ACROSS SOUTHERN WI AND EAST CENTRAL MN. THERE WILL BE
ONGOING WARM AIR ADVECTION /WAA/ AT ALL LEVELS OVER SOUTHERN
WI...BUT ESPECIALLY AT 700 MB DURING THIS TIME.
THAT INVERTED TROUGH AXIS WILL TAKE ON A MORE EAST TO WEST
ORIENTATION AS THE UPPER LOW SITS OVER SOUTHERN IL AND TAKES ON A
SLIGHTLY NEGATIVE TILT. 850-700MB WAA WILL CONTINUE OVER SOUTHERN
WI. THE AXIS OF 850-600MB FRONTOGENESIS WILL ALSO SIT SOMEWHERE IN
THE VICINITY OF SOUTHERN WI...DEPENDING ON THE MODEL OF CHOICE. THIS
AXIS IS SHOWN TO PIVOT RIGHT OVER SOUTH CENTRAL WI FROM 15Z-21Z ON
THE 06Z NAM BEFORE SHIFTING SOUTHEAST LATER AS THE SURFACE AND UPPER
LOW CONTINUE ESE. THE AXIS OF HIGHEST DEEP-LAYER Q-VECTOR
CONVERGENCE WILL SIT OVER SOUTHERN WI FOR A LONG TIME. OMEGA VALUES
WILL BE HIGH DURING THIS TIME PERIOD AS WELL.
THE CANADIAN MODELS BOTH CONTINUE A LOW TRACK FURTHER SOUTH THAN
OTHER MODELS...AND THEREFORE HAVE LIGHTER QPF OVER OUR FORECAST AREA
/CWA/. THE 12Z ECMWF HAD RATHER HIGH QPF OVER SOUTH CENTRAL WI...AS
DID THE 00Z NAM. THE GFS HAS BEEN A STEADY COMPROMISE BETWEEN MANY
OF THE MODELS. THE 00Z ECMWF CAME IN WITH LIGHTER QPF IN SOUTH
CENTRAL WI THAN THE 12Z RUN...BUT HAD SIMILAR QPF ELSEWHERE. THE
CONSENSUS OF ALL MODELS SEEMED TO BE A REASONABLE STARTING POINT FOR
QPF AND THEN BLENDED IT WITH THE HPC QPF AMOUNTS.
TOOK A GENERAL AVERAGE OF SNOW RATIOS BASED ON COBB...1000-500MB
THICKNESSES AND MODEL OUTPUT. SNOW RATIOS SHOULD RANGE FROM 16 IN
THE WESTERN CWA TO 10:1 IN THE EAST AT 12Z TUE...THEN RISE TO A
17-12:1 RANGE AT 18Z TUE...THEN END UP AT 15-16:1 FOR THE WHOLE CWA
AT 00Z WED. 6-HR SNOWFALL AMOUNTS SHOULD BE IN THE 3 TO 5 INCH RANGE
IN SOUTH CENTRAL AND PORTIONS OF SOUTHEAST WI FOR THE WHOLE DAY TUE.
STORM TOTAL SNOWFALL AMOUNTS OF 9 TO 12 INCHES EXPECTED SOUTH
CENTRAL FOR A ROUGHLY 24-HOUR PERIOD.
EXPECTING FAIRLY HIGH SNOWFALL RATES DURING THE DAY ON TUE DUE TO
THE STRONG WAA/VORTICITY ADVECTION AND FRONTOGENESIS SITTING OVER
THE AREA. THIS WILL HAVE A HIGH IMPACT ON BOTH THE MORNING AND
AFTERNOON COMMUTES FOR MOST OF THE FORECAST AREA. DECIDED TO ROLL
THE WESTERN CWA INTO A WINTER STORM WARNING AT 06Z TUE AND THE
EASTERN CWA AT 12Z TUE. WE ARE KEEPING FOND DU LAC AND SHEBOYGAN
COUNTIES IN A WATCH FOR NOW SINCE SNOW AMOUNTS DO NOT LOOK HIGH
ENOUGH AT THIS TIME TO JUSTIFY A WARNING. LATER SHIFTS WILL NEED TO
ASSESS IF THIS AREA NEEDS A WARNING OR JUST AN ADVISORY.
MODELS SUGGEST THAT THE LOW LEVEL CONVERGENCE AND LAKE ENHANCEMENT
SHOULD ONLY INCREASE QPF AMOUNTS BY A FEW HUNDREDTHS.
.LONG TERM...
WEDNESDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM
HIGH PRESSURE WILL MOVE ACROSS THE UPPER MIDWEST ON WED INTO THU.
WARM ADVECTION IN SOUTHERN WI AHEAD OF THE NEXT UPPER TROUGH WILL
LEAD TO TEMPS RISING INTO THE UPPER 30S AND LOWER 40S BY THE END OF
NEXT WEEK. THERE COULD BE SOME LIGHT PRECIP IN THE FORM OF EITHER
RAIN OR SNOW OR DRIZZLE FRI NIGHT AND SATURDAY WITH THE WARM AIR
ADVECTION PATTERN AND A SHORTWAVE. IT WILL DEPEND ON HOW QUICKLY A
CLOSED UPPER LOW OVER THE SOUTHWEST EJECTS INTO THE PLAINS FOR
WHETHER THE LATTER HALF OF THE WEEKEND WILL BE IN THE 40S OR THE 20S
FOR HIGH TEMPS.
&&
.AVIATION/12Z TAFS/...
WILL GRADUALLY INCREASE CLOUD COVERAGE AND SLOWLY LOWER HEIGHTS FROM
WEST TO EAST TODAY. WILL KEEP AN EYE ON RADAR TRENDS...BUT PLAN IS
TO KEEP PREVIOUS FORECAST TREND OF NO SNOW AT KMSN UNTIL CLOSER
TO/JUST AFTER 00Z TUE...AND EASTERN TAF SITES UNTIL 06Z OR LATER.
SHOULD KEEP VFR CIGS VSBYS UNTIL STEADIER SNOW BEGINS...THEN GO TO
MVFR. IFR VSBYS AND 1 IN/HOUR ACCUMULATION RATES SHOULD HOLD OFF
UNTIL AFTER 12Z TUESDAY. EAST WINDS WILL BE SLOWLY INCREASING...WITH
OCCASIONAL 15 TO 20 KNOT GUSTS MIXING DOWN AFTER 06Z.
&&
.MARINE...CURRENT WIND AND WAVE HEIGHT FORECASTS INDICATE A SMALL
CRAFT ADVISORY WILL LIKELY BE NEEDED FROM TUESDAY THROUGH WEDNESDAY
MORNING EVERYWHERE...AND POSSIBLY THROUGH WEDNESDAY AFTERNOON IN THE
SOUTH. START TIME IS A BIT IN QUESTION...AND WITH SURROUNDING
OFFICES HOLDING OFF AT THIS TIME...WILL NOT ISSUE ADVISORY...BUT
WOULD NOT BE SURPRISED TO SEE ONE HOISTED LATER THIS MORNING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WARNING FROM 6 AM TUESDAY TO MIDNIGHT CST TUESDAY
NIGHT FOR WIZ058>060-064>066-070>072.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR WIZ046-047-056-057-062-063-067>069.
WINTER STORM WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
FOR WIZ051-052.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
TUESDAY THROUGH SUNDAY...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
343 AM CST MON MAR 4 2013
.SHORT TERM...TODAY THROUGH WEDNESDAY
343 AM CST MON MAR 4 2013
FORECAST FOCUS REMAINS ON WINTER STORM IMPACTING THE REGION TODAY
THROUGH TUESDAY.
LATEST WATER VAPOR IMAGERY AND RAP 500 MB ANALYSIS SHOWED A POTENT
LOW CENTERED OVER WESTERN MONTANA. A LEADING SHORTWAVE WAS MOVING
EAST ACROSS WESTERN MINNESOTA/IOWA. A BAND OF LIGHT SNOW EXTENDED
FROM WEST CENTRAL MINNESOTA...SOUTHEAST THROUGH SOUTHEAST
MINNESOTA INTO EASTERN IOWA. VISIBILITIES WITHIN THIS BAND HAD
FALLEN INTO THE 1 TO 2 MILE RANGE.
THE ONGOING BAND OF SNOW WILL CONTINUE MOVING EAST/NORTHEAST THIS
MORNING ACROSS NORTHEAST IOWA AND SOUTHEAST MINNESOTA...APPROACHING
THE MISSISSIPPI RIVER DURING THE MID TO LATE MORNING HOURS.
MESOSCALE MODELS SHOW THE BAND REALLY FALLING APART AS IT MOVES
INTO WESTERN WISCONSIN LATE THIS MORNING INTO EARLY THIS AFTERNOON
AND REALLY NOT MAKING IT TO THE INTERSTATE 94 CORRIDOR AS IT
ENCOUNTERS VERY DRY AIR. KEAU FORECAST SOUNDINGS SHOW THE DRY AIR
EXTENDING FROM THE SURFACE THROUGH AROUND 5KFT...SO IT WILL TAKE
SOME TIME FOR SATURATION TO OCCUR. SNOW ACCUMULATIONS TODAY WILL
BE ON THE LIGHT SIDE RANGING FROM 1 TO POSSIBLY 3 INCHES OVER
SOUTHEAST MINNESOTA INTO NORTHEAST IOWA TO AROUND AN INCH OVER FAR
WESTERN WISCONSIN. FRONTOGENESIS INCREASES...IN THE 850-700 MB
LAYER...THIS AFTERNOON RIGHT ALONG THE MISSISSIPPI RIVER. THIS
COULD KEEP LIGHT SNOWFALL INTO THE EARLY AFTERNOON HOURS BEFORE IT
WANES. GFS FORECAST SOUNDINGS THIS AFTERNOON OVER SOUTHEAST
MINNESOTA....NORTHEAST IOWA...AND FAR SOUTHWEST WISCONSIN SHOW A
LOSS OF ICE ALOFT WHICH COULD LEAD TO SOME FREEZING DRIZZLE. THE
NAM ON THE OTHER HAND KEEPS THE ICE ALOFT ACROSS THESE AREAS.
GIVEN THE CONSISTENT SIGNAL FOR A LOSS OF ICE IN THE GFS WILL
INTRODUCE A SLIGHT CHANCE OF FREEZING DRIZZLE ACROSS THESE AREAS
THIS AFTERNOON INTO EARLY THIS EVENING.
THE LOW WILL DIVE SOUTHEAST TONIGHT INTO THE UPPER MISSISSIPPI RIVER
VALLEY. VERY IMPRESSIVE LARGE SCALE FORCING ASSOCIATED WITH THE LOW
WITH DEEP QG FORCING NOTED PARTICULARLY IN THE 700-500 MB LAYER. A
BROAD AREA OF ISENTROPIC LIFT...MAINLY FOCUSED ON THE 280-310 K
SURFACES...WILL DEVELOP ACROSS THE FORECAST AREA THIS EVENING AND
CONTINUE THROUGH THE OVERNIGHT HOURS. SREF PROBABILITIES FOR SNOWFALL
RATES OF AN INCH PER HOUR DEVELOP ACROSS MOST OF THE FORECAST AREA
THIS EVENING AND CONTINUE THROUGH THE OVERNIGHT HOURS INTO TUESDAY
MORNING. OVERALL FORECAST MODELS ARE IN CLOSE AGREEMENT THIS CYCLE
PLACING A BROAD SWATH OF HEAVY SNOW ACROSS MUCH OF THE AREA WITH
ACCUMULATIONS RANGING FROM 8 TO 13 INCHES. THE HIGHEST
ACCUMULATIONS WILL BE ALONG THE MISSISSIPPI RIVER...AND INCLUDING
ALL OF SOUTHWEST WISCONSIN. DECIDED TO ISSUE A WINTER STORM
WARNING FOR CENTRAL AND NORTH CENTRAL WISCONSIN STARTING AT 6 PM
THIS EVENING AND CONTINUING THROUGH 6 PM TUESDAY. WILL CONTINUE
THE WINTER STORM WARNING FOR THE REST OF THE FORECAST AREA...BUT
PLAN ON THE BULK OF THE ACCUMULATING SNOW TO OCCUR TONIGHT THROUGH
TUESDAY MORNING. GIVEN THE FORCING OVERNIGHT INTO TUESDAY
MORNING...THE SNOW WILL BE HEAVY AT TIMES ESPECIALLY FOR THE
TUESDAY MORNING COMMUTE. THE SNOW IS EXPECTED TO TAPER OFF FROM
NORTHWEST TO SOUTHEAST LATE TUESDAY AFTERNOON AND FINALLY EXIT THE
AREA TUESDAY NIGHT. THE PRESSURE GRADIENT TIGHTENS ACROSS THE AREA
TUESDAY AFTERNOON INTO TUESDAY EVENING WITH NORTH WINDS INCREASING
TO 10 TO 17 MPH WITH GUSTS AROUND 25 MPH POSSIBLE. WILL HAVE TO
KEEP A CLOSE WATCH ON THE POTENTIAL FOR BLOWING SNOW. ALSO...LOW
TEMPERATURES TUESDAY NIGHT COULD BE CHALLENGING WITH THE FRESH
SNOW PACK AND DECREASING CLOUDS. IF CLOUDS CLEAR EARLIER THAN
FORECAST LOWS COULD BE SEVERAL DEGREES COLDER.
HIGH PRESSURE IS EXPECTED TO BUILD INTO THE REGION ON WEDNESDAY AS
RIDGING INTENSIFIES OVER THE CENTRAL CONUS. PLAN ON PARTLY TO MOSTLY
SUNNY SKIES AND SLIGHTLY BELOW NORMAL TEMPERATURES WITH HIGHS RANGING
FROM THE LOWER 30S OVER NORTHERN WISCONSIN TO THE MID 20S ACROSS
SOUTHEAST MINNESOTA.
.LONG TERM...THURSDAY THROUGH SUNDAY
343 AM CST MON MAR 4 2013
04.00 MEDIUM RANGE MODELS ARE IN AGREEMENT THURSDAY INTO FRIDAY
SHOWING RIDGING OVER THE UPPER MIDWEST. A SHORTWAVE LOOKS TO PASS
JUST NORTH OF THE AREA ACROSS NORTHERN MINNESOTA THROUGH SOUTHERN
ONTARIO. THIS FEATURE WILL BRING A SLIGHT CHANCE OF SNOW TO FAR
NORTHERN WISCONSIN AS IT MOVES THROUGH THURSDAY NIGHT. MODEL
SOLUTIONS START TO DIVERGE LATE FRIDAY THROUGH THE WEEKEND WITH THE
HANDLING OF AN UPPER LOW OVER THE DESERT SOUTHWEST. THE ECMWF TAKES
THE LOW INTO THE PLAINS ON SATURDAY...LIFTING INTO THE UPPER
MISSISSIPPI RIVER VALLEY SUNDAY INTO MONDAY. THE GFS KEEPS A CUTOFF
LOW OVER THE SOUTHWEST AND BRINGS AN OPEN WAVE ACROSS THE REGION.
GIVEN THE MODEL DIFFERENCES WILL LEAN TOWARD A MODEL CONSENSUS BLEND
THROUGH THE WEEKEND WITH PRECIPITATION CHANCES FRIDAY NIGHT THROUGH
SUNDAY. WILL HAVE TO KEEP A CLOSE WATCH ON THE NEXT FEW FORECAST
MODEL RUNS SINCE THE SOUTHWEST LOW HAS THE POTENTIAL TO BRING RAIN
AND MUCH WARMER TEMPERATURES TO THE AREA. THE ECMWF WARMS
TEMPERATURES INTO THE 50S ON MONDAY AND BRINGS NEARLY 1/2 INCH OF
RAIN INTO THE AREA. THROUGH THE WEEKEND...PLAN ON TEMPERATURES NEAR
TO SLIGHTLY ABOVE NORMAL WITH HIGHS IN THE UPPER 30S TO AROUND 40.
&&
.AVIATION...
1130 PM CST SUN MAR 3 2013
VERY CHALLENGING FORECAST FOR THE NEXT 24-36 HOURS.
SHORTWAVE TROUGH SPAWNING AN AREA OF SNOW/MIXED PCPN OVER SOUTHWEST
MN/WESTERN IA. MUCH DRIER AIR CLOSER TO THE TAF SITES THOUGH...PER
00Z DVN/MPX SOUNDINGS...AND THIS WILL NEED TO COOL AND
SATURATION...WHICH MAKES -SN THE PCPN TYPE LOCALLY. HOWEVER...THERE
IS A LOT OF SATURATION THAT NEEDS TO BE ACCOMPLISHED...AND THE MESO
MODELS ALONG WITH THE LATEST NAM/GFS RUNS CONTINUE TO DEPICT A
DIMINISHING TREND IN INTENSITY AND AREAL COVERAGE OF THE PCPN BAND.
WILL DELAY ONSET OF VSBY RESTRICTING -SN BASED ON THIS. AMOUNTS
WON/T BE MUCH TODAY AS A RESULT. ABOUT 1 TO 2 AT KRST...PERHAPS UP
TO AN INCH AT KLSE. THE CAVEAT HERE IS SOME OF THE MESO MODELS
SUGGEST CONVECTIVE ELEMENTS POST THIS SNOW BAND. IF THESE WOULD MOVE
IN...AN INCH IN AN HOUR WOULD BE POSSIBLE...ALONG WITH 1SM VSBYS.
CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN TAFS AT THIS TIME. CIGS
SHOULD CONTINUE TO LOWER THROUGH THE DAY THOUGH.
A STRONGER UPPER LEVEL SHORTWAVE WILL MOVE IN FOR MONDAY
NIGHT...IMPACTING THE REGION THROUGH TUESDAY. THIS SYSTEM WILL PACK
MORE OF A PUNCH...WITH HIGH SNOW RATES/SNOW FALL AMOUNTS. LIFR/IFR
CIGS ARE EXPECTED ON TUE...WITH VSBYS 1/2 TO 1 1/2SM IN SN. WINDS
WILL BLOW AND DRIFT MUCH OF THE SNOW...FURTHER LOWERING VSBYS AND
IMPACTING RUNWAY CLEARING OPERATIONS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
343 PM CST SUN MAR 3 2013
WI...WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
WIZ032-033-041-053>055-061.
WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY
AFTERNOON FOR WIZ017-029-034-042>044.
MN...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR MNZ079-086-087-094-095.
WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
MNZ088-096.
IA...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY
FOR IAZ008-009-018-019.
WINTER STORM WARNING FROM 6 AM MONDAY TO 6 PM CST TUESDAY FOR
IAZ010-011-029-030.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
300 AM EST WED MAR 6 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A FAIRLY AMPLIFIED UPPER
LEVEL PATTERN ACROSS THE CONUS EARLY THIS MORNING. LARGE LONGWAVE
RIDGING IS NOW IN PLACE ACROSS MUCH OF THE INTER-MOUNTAIN WEST AND
CENTRAL PLAINS WITH THE DOWNSTREAM FLOW DROPPING QUICKLY INTO A
SHARP TROUGH OVER THE EASTERN STATES. THIS TROUGH IS ANCHORED BY A
TIGHT/POTENT UPPER LEVEL LOW EXITING THE TN VALLEY TOWARD THE
MID-ATLANTIC COAST. THIS ENERGY AND ASSOCIATED SURFACE FEATURE WILL
BRING A SIGNIFICANT SNOWFALL TO PARTS OF THE MID-ATLANTIC THROUGH
WEDNESDAY. OUR FORECAST AREA RESIDES AT THE BASE OF THIS
TROUGH...FAR REMOVED FROM ANY SIGNIF MID/UPPER LEVEL SYNOPTIC/QG
FORCING. WV IMAGERY SHOWS A NARROW BAND OF MOISTURE DROPPING SOUTH
ACROSS THE PENINSULA FOLLOWED QUICKLY BY MARKED DRYING/SUBSIDENCE IN
THE WAKE OF THE PASSING SHORTWAVE JUST TO OUR NORTH. THIS DRYING
WILL OVERSPREAD OUR SKIES THROUGH THE DAY. THERE IS ALSO QUITE A
SURGE OF COLD AIR ABOVE THE SURFACE ASSOCIATED WITH THIS SYSTEM TO
OUR NORTH...HOWEVER THE MAIN SURGE OF THIS AIRMASS WILL BE TOWARD
THE GA/CAROLINA COAST AND PREVENT THE ARRIVAL OF ANOTHER AIRMASS
COMPARABLE TO WHAT WAS SEEN THIS PREVIOUS WEEKEND.
AT THE SURFACE...WELL DEFINED COLD FRONT IS QUICKLY DROPPING TO THE
SOUTHEAST INTO THE NORTH-CENTRAL FL PENINSULA. JUST ENOUGH MOISTURE
IN THE LOW LEVELS AND FRONTAL FOCUS THIS MORNING TO SUPPORT A NARROW
BAND OF BROKEN (MAINLY LIGHT) SHOWERS. WINDS PICK UP QUICKLY FROM
THE NW IN THE WAKE OF THE FRONT...AND IT WILL LIKELY BE FAIRLY
EVIDENT BY THIS SURGE OF WIND WHEN THE FRONT PASSES ANY GIVEN
LOCATION THROUGH THE MORNING HOURS.
&&
.SHORT TERM (TODAY THROUGH FRIDAY)...
TODAY...COLD FRONT WILL QUICKLY DROP SOUTH THROUGH AND OUT OF THE
FORECAST AREA THIS MORNING. CURRENT GRIDS SHOW THE FRONT PASSING
SOUTH OF FT. MYERS BY LATE MORNING. THERE WILL BE A CHANCE OF A
BRIEF SHOWER OR SPRINKLE AHEAD OF THIS FRONT TO THE SOUTH OF TAMPA
BAY THROUGH MID MORNING...HOWEVER ANY RAINFALL WILL NOT AMOUNT TO
MUCH. BY SUNRISE...THE FRONT LOOKS TO HAVE ALREADY PASSED TAMPA BAY
AND POINTS NORTH TAKING ANY SCATTERED SHOWERS SOUTHWARD WITH IT.
THEREFORE...FORECAST WILL SHOW SKIES CLEARING FROM NORTH TO SOUTH
THROUGH THE DAY WITH MOST OF THE REGION SEEING ABUNDANT SUNSHINE BY
EARLY AFTERNOON. EXPECTING A BREEZY/GUSTY DAY WITH NW WINDS BEHIND
THE FRONT...AND A LAKE WIND ADVISORY HAS BEEN ISSUED FOR THIS
MORNING THROUGH EARLY EVENING. THE MOST EVIDENT CAA WILL BE NORTH OF
THE I-4 CORRIDOR WHERE HIGH TEMPS WILL HOLD IN THE LOW/MID 60S.
SOUTH OF I-4 TEMPS WILL MAKE A RUN AT 70. COOLEST TEMPS WILL BE
ALONG THE COAST FROM MANATEE COUNTY NORTHWARD WITH FLOW OFF THE
RELATIVELY COOLER SHELF WATERS. THE STRONG NW WINDS WILL ALSO BRING
BUILDING SWELL/SURF FOR AREA BEACHES AND WILL RESULT IN A
MODERATE/ELEVATED RISK OF RIP CURRENTS FROM PINELLAS COUNTY
SOUTHWARD. THIS ELEVATED RISK SHOULD LINGER INTO THURSDAY MORNING
BEFORE THE SWELL AND ONSHORE WIND COMPONENT BEGINS TO DECLINE.
TONIGHT...A CHILLY MARCH NIGHT IN STORE IN THE DRY POST-FRONTAL
ENVIRONMENT. SOME OF THE STATISTICAL GUIDANCE IS SHOWING READINGS A
COUPLE OF DEGREES BELOW FREEZING FOR THE INTERIOR NATURE COAST.
HOWEVER...STATISTICAL GUIDANCE IS ALMOST ALWAYS AT LEAST SEVERAL
DEGREES TOO COLD WITH ADVECTION SCENARIOS ON THE FIRST NIGHT BEHIND
FRONTS. THERE IS NO DOUBT THAT IT WILL BE A COLD (MIDDLE/UPPER 30S
COMMON AWAY FROM THE COAST...BUT AT THIS TIME WILL KEEP TEMPERATURES
JUST ABOVE FREEZING...EVEN UP TOWARD CITRUS AND LEVY COUNTIES. ALSO
SINCE THE GRADIENT WILL STAY UP AND OVERNIGHT DEWPOINT DEPRESSIONS
ARE FORECAST TO BE 5-8 DEGREES...THE THREAT OF FROST APPEARS LOW.
EACH OF THESE FACTORS WILL NEED TO BE RE-EVALUATED DURING THE DAY.
THURSDAY/THURSDAY NIGHT...
A BROAD DEEP LAYER NORTHWEST FLOW WILL BE IN PLACE ON THE BACKSIDE
OF LONGWAVE TROUGHING OFF THE ATLANTIC SEABOARD. THIS FLOW WILL KEEP
A STEADY SUPPLY OF DRY AIR ARRIVING FROM THE NORTH. MAY SEE A BOUT
OF HIGHER CIRRUS LATER THURSDAY/THURSDAY EVENING OVER THE NORTHERN
HALF OF THE STATE ASSOCIATED WITH A WEAK PASSING SHORTWAVE...BUT
OTHERWISE SKIES LOOK TO BE MOSTLY CLEAR. WINDS WILL BE LESS GUSTY
FOR THURSDAY AS SURFACE RIDGING CONTINUES TO BUILD IN FROM THE
NORTHWEST. HIGH TEMPS WILL GENERALLY REACH THE UPPER 60S TO NEAR 70
NORTH AND THE LOWER/MID 70S SOUTH. BEACH TEMPS WILL LIKELY AGAIN BE
HELD IN THE 60S WITH AT LEAST SOME ONSHORE FLOW COMPONENT...
ESPECIALLY NORTH OF LEE/CHARLOTTE COUNTIES. WIDESPREAD 40S THURSDAY
NIGHT FOR LOW TEMPS...WITH SOME UPPER 30S FOR THE NATURE COAST.
FRIDAY...
"CHAMBER OF COMMERCE" WEATHER TO END THE WORK WEEK AFTER A COOL
EARLY MORNING START. STACKED RIDGING WILL BE BUILDING EASTWARD
ACROSS THE GULF TOWARD THE AREA CONTINUING A FORECAST OF ABUNDANT
SUNSHINE AND WARMING TEMPERATURES.
&&
.LONG TERM (FRIDAY NIGHT THROUGH NEXT TUESDAY)...
THE PERIOD BEGINS WITH DEEP LAYER RIDGING FROM THE GULF TO THE
GREAT LAKES. THROUGH THE WEEKEND THIS RIDGING SLOWLY SHIFTS EAST
ACROSS THE AREA WITH DRY AND SEASONABLE CONDITIONS AS WINDS VEER
FROM NORTH TO SOUTHEAST AND MAY BE ROBUST AT TIMES ON THE GULF.
BY MON THE RIDGING WILL BE EAST OF FL AS AN UPPER LOW/TROUGH
WITH AN ATTENDANT SURFACE FRONT MOVES INTO THE MID CONUS. THIS
SYSTEM CONTINUES EAST TUE...PUSHING THE FRONT DOWN THE STATE WITH
INCREASING CLOUDS AND A SLIGHT CHANCE OF SHOWERS SPREADING
SOUTHWARD. THE LATEST GFS AND ECMWF GUIDANCE WERE FAIRLY CONSISTENT
THROUGH THE PERIOD BUT BEGIN TO DIVERGE TUE WITH THE ECMWF SLOWER
THAN THE GFS IN MOVING THE FRONT ACROSS FL.
&&
.AVIATION...
APPROACHING FRONT WILL SPREAD SHRA/VCSH UNDER BKN MVFR CIGS
SOUTHWARD...BEGINNING AT 09Z IN THE NORTH AND ENDING AROUND 18Z IN
THE SOUTH. SOUTH AND SW WINDS SHIFT TO NW AND GUSTY FOR THE LATE
MORNING AND AFTERNOON.
&&
.MARINE...
A COLD FRONT WILL QUICKLY PASS SOUTH THROUGH THE EASTERN GULF OF
MEXICO THIS MORNING. WINDS FROM THE NORTHWEST AND SEAS WILL RAPIDLY
INCREASE TO ADVISORY LEVELS BEHIND THE FRONT AND LINGER THROUGH THE
DAY AND EVENING. LATER TONIGHT...WINDS AND SEAS WILL BEGIN TO
SUBSIDE. WINDS AND SEAS WILL GENERALLY REMAIN BELOW HEADLINE
CRITERIA FROM THURSDAY AFTERNOON THROUGH THE DAYLIGHT HOURS FRIDAY
AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THIS RIDGE SLIDES
EASTWARD FOR THE UPCOMING WEEKEND SETTING UP A GOOD SCENARIO FOR
NOCTURNAL AND EARLY MORNING EASTERLY WIND SURGES. THESE SURGES ARE
CURRENTLY FORECAST TO REACH CAUTIONARY LEVELS BOTH FRIDAY NIGHT AND
SATURDAY NIGHT.
&&
.FIRE WEATHER...
DRY AIR ARRIVING BEHIND A COLD FRONT WILL COMBINE WITH GUSTY NW
WINDS AND ERC VALUES ABOVE 27 TO RESULT IN RED FLAG CONDITIONS FOR
MOST OF THE REGION THIS AFTERNOON. THE ONLY EXCEPTIONS WILL BE NEAR
THE COAST WHERE ONSHORE FLOW SHOULD HELP PREVENT CRITICAL RELATIVE
HUMIDITY LEVELS. SEVERAL HOURS OF CRITICALLY LOW RELATIVE HUMIDITY
APPEAR LIKELY FOR THURSDAY LATE MORNING/AFTERNOON AS WELL.
HOWEVER...LIGHTER WINDS AND CURRENT ERC VALUES BELOW 37 DO NOT
MATCH RED FLAG CRITERIA FOR ANY ZONES. THIS POTENTIAL FOR RED FLAG
CONDITIONS CAN BE RE-EVALUATED THIS AFTERNOON WITH THE ISSUANCE OF
THE NEW ERC VALUES. IF ANY ZONES RISE TO 37 OR HIGHER...WARNINGS
WILL LIKELY BECOME REQUIRED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 64 43 67 47 / 10 0 0 0
FMY 72 44 71 48 / 30 0 0 0
GIF 68 40 72 44 / 10 0 0 0
SRQ 65 44 67 46 / 20 0 0 0
BKV 64 36 68 38 / 10 0 0 0
SPG 63 49 67 53 / 10 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST
THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-
HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE-
PASCO-PINELLAS-POLK-SARASOTA-SUMTER.
RED FLAG WARNING FROM NOON TODAY TO 7 PM EST THIS EVENING
FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS-
HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-POLK-SARASOTA-
SUMTER.
BEACH HAZARDS STATEMENT THROUGH THURSDAY MORNING FOR
CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR TARPON
SPRINGS TO SUWANNEE RIVER OUT 20 NM-TARPON SPRINGS TO
SUWANNEE RIVER OUT 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR BONITA
BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-
TAMPA BAY WATERS.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
356 AM CST WED MAR 6 2013
.SHORT TERM /TODAY /...
MAIN FORECAST CONCERN TODAY IS LINGERING
STRATUS DECK AND WHETHER IT WILL DISSIPATE DURING THE AFTERNOON.
SURFACE HIGH AND UPPER LEVEL RIDGE BUILD INTO THE STATE PAST 18Z
TODAY AND BRING LIGHT FLOW TO THE FORECAST AREA. INVERSION
STRENGTHENS AS DRIER AIR FILTER WITH THE UPPER RIDGE MOVING INTO THE
STATE THIS AFTERNOON. STRATUS DECK EXTENDS UP INTO CANADA AND THE
GENERALLY NORTH FLOW CONTINUES THROUGH AT LEAST MIDDAY BEFORE WINDS
BECOME LIGHT AND VARIABLE. LOW CONFIDENCE WITH STRATUS DISSIPATING
BEFORE 18Z AND EVEN AT ALL THROUGH THE AFTERNOON. VERY MINIMAL
MIXING AND IF STRATUS DECK REMAINS IN PLACE WHEN SURFACE HIGH SLIDES
OVER CENTRAL IOWA...THINKING IT WILL BECOME TRAPPED UNDERNEATH THE
INVERSION INTO THIS EVENING OR POSSIBLY TOMORROW BEFORE THE WAA
DEVELOPS ON THE BACKSIDE OF THE SURFACE HIGH. AS A
RESULT...INCREASED SKY COVER THROUGH THE AFTERNOON WITH IT SLOWLY
DISSIPATING PAST 21Z. THE 05Z HRRR KEEPS THE STRATUS GOING THROUGH
THE AFTERNOON EXCEPT THE FAR SOUTHWEST. WRT TO TEMPS TODAY...LEANED
TOWARD THE NAM FOR MAX TEMPS TODAY AS IT SEEMS TO HAVE A GOOD HANDLE
ON THE STRATUS AS WELL.
.LONG TERM /TONIGHT THROUGH TUESDAY/...
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS IOWA TONIGHT. STILL
UNCERTAIN HOW WIDESPREAD THE STRATUS WILL BE OVERNIGHT. THE
STRATUS WILL BE TOUGH TO GET RID OF OVERNIGHT IF IT SURVIVES TODAY
WITH VERY LITTLE SUBSIDENCE OR STEERING FLOW IN PLACE. THE
UNCERTAINTY WITH THE STRATUS LEAVES A WIDE RANGE IN POSSIBLE LOW
TEMPERATURES OVERNIGHT. TEMPERATURES WILL DROP WELL INTO THE
SINGLE DIGITS OVERNIGHT ACROSS THE NORTHEAST WITH CLEARING BUT
WOULD REMAIN IN THE MID TO UPPER TEENS IF CLOUDS PERSIST. HAVE
LEANED TOWARDS CLEARING OR PARTIAL CLEARING AND COLDER
TEMPERATURES AT THIS TIME. THE HIGH PRESSURE RIDGE SHIFTS EAST ON
THURSDAY WITH RETURN FLOW DEVELOPING IN ADDITION TO A TRANSITION
TO MID LEVEL RIDGING. THIS WILL CONTINUE INTO FRIDAY WITH EVEN
WARMER TEMPERATURES EXPECTED IN THE UPPER 30S TO UPPER 40S.
A POTENT UPPER LEVEL SYSTEM CONSISTING OF SEVERAL STRONG SHORT
WAVES ROTATING AROUND THE CORE WILL BEGIN TO MOVE OVER CALIFORNIA
ON FRIDAY. ANOTHER SHORT WAVE UNDERCUTTING THE SYSTEM WILL PUSH
OUT AHEAD AND ARRIVE OVER NEBRASKA AND IOWA BY FRIDAY NIGHT. AN
INCREASING LOW LEVEL JET AND ASSOCIATED STRONG THETA-E ADVECTION
ALONG WITH THE QG FORCING FROM THE UPPER WAVE WILL HELP SHOWERS
AND A FEW THUNDERSTORMS DEVELOP ACROSS MAINLY CENTRAL AND WESTERN
IOWA. OVERNIGHT LOW TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE
FREEZING WITH LOW LEVEL MOISTURE SURGE BRINGING DEWPOINTS IN THE
3OS TO THE AREA. THE FORECAST AREA WILL BE IN THE WARM SECTOR
THROUGH THE DAY SATURDAY. THE PRIMARY UPPER LEVEL SYSTEM WILL LIFT
INTO THE MIDWEST SATURDAY NIGHT INTO SUNDAY. THE ECMWF IS A BIT
FASTER WITH THE SFC FEATURES WITH THE COLD FRONT DROPPING THROUGH
MUCH OF CENTRAL IOWA BY 12Z SUNDAY WHILE THE GFS IS A BIT SLOWER.
ANY PRECIPITATION WILL SWITCH OVER TO SNOW BEHIND THE COLD FRONT
AS PROFILES COOL. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE. COLD
ADVECTION WILL BE PROMINENT MUCH OF THE DAY SUNDAY WITH HIGH
TEMPERATURES EARLY IN THE DAY. 850 MB TEMPERATURES BY 12Z MONDAY
WILL BE -8C TO -10C ACROSS MUCH OF THE AREA AND HAVE CONTINUED THE
COOLING TREND INTO MONDAY. SOME MODERATION FOR THE END OF THE
PERIOD WITH LOW CHANCES FOR PRECIPITATION.
&&
.AVIATION...06/06Z
MVFR STRATUS CONTINUES TO STREAM ACROSS THE STATE FROM THE NNW WITH
A FEW PATCHES OF VFR CONDITIONS SCATTERED ABOUT IOWA AND MINNESOTA.
THE VFR CEILINGS HAVE BEEN DECREASING IN COVERAGE OVER THE LAST
COUPLE OF HOURS SO HAVE NOT MENTIONED ANYTHING HIGHER THAN MVFR IN
THE TAF PACKAGE. HIGH IFR CEILINGS ARE POSSIBLE ACROSS THE NORTH
TONIGHT AS WELL. HAVE CONTINUED TO PUSH BACK THE CLEARING OF THE
STRATUS INTO THE MID MORNING TOMORROW GIVEN THE LARGE SHIELD OF
STRATUS EXTENDING UPSTREAM INTO MN AND MANITOBA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...KS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
400 AM EST WED MAR 6 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW
WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD
OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE TRANSITION BETWEEN PHASES OF THIS INTENSE AND IMPACTFUL INCOMING
SNOWSTORM IS FULLY UNDERWAY. THE INITIAL SFC LOW THAT DROPPED DOWN
FROM THE NRN PLAINS INTO THE UPPER MIDWEST IS ABOUT TO BE
PHASED-OUT. THE NEWER AND STRONGER LOW CURRENTLY OVER THE RALEIGH NC
AREA WILL CREATE A SNOWY AND HAZARDOUS WEDNESDAY FOR MUCH OF THE
MID-ATLC. THE NEXT SEVERAL HOURS WILL BE THE CRITICAL TRANSITION
PERIOD AS THIS LOW INTENSIFIES AND ROTATES DUE NE TOWARD THE LOWER
TIP OF THE DELMARVA PENINSULA AND DEVELOPS HEAVY SNOW BAND ACROSS
THE NWRN QUADRANT OF THE LOW DURING THE DAYTIME HRS.
THROUGH DAYBREAK...
A REGIONAL VIEW OF THE RADAR RETURNS SHOWS THAT SNOW STILL AFFECTING
MUCH OF THE UPPER MIDWEST...FROM CNTRL IN TO THE APLCNS...BUT THIS
AREA OF PRECIP REGION WILL DISSIPATE IN THE NEXT FEW HRS. ONLY
POCKETS OF HIGHER ELEVATION UPSLOPE SNOW WILL CONTINUE ALONG THE
APLCN CHAIN.
THE FIRST PHASE OF THE SYSTEM THAT BROUGHT LIGHT TO MODERATE SNOW
OVER THE ENTIRE REGION IN JUST THE PAST FEW HOURS IS JUST THE START.
ABOUT A HALF-FOOT OF SNOW HAS ALREADY FALLEN OVER THE HIGHER TERRAIN
OF THE CNTRL APLCNS...TOWARD THE BLUE RIDGE. A FEW INCHES HAVE
BEEN COMMON OVER THE SWRN QUADRANT OF THE CWA THRU 2-3AM. THE
HEAVIER BANDS THAT BROUGHT THIS ACTIVITY ARE NOW SPREADING ACROSS
THE DC/BALT AND THE PIEDMONT AREAS. THIS ACTIVITY WILL CREATE THE
FIRST LAYER OF SNOW AND ALLOW FOR THE INITIAL BASE FOR ACCUMULATIONS
FROM THE SECOND PHASE OF THE STORM.
WINDS HAVE BEEN INTERMITTENTLY INCREASED...NORMALLY W/ SOME OF THE
HEAVIER BANDS BUT THEN DROP BACK DOWN TO 5-10MPH. THESE LOWER WIND
SPEEDS ARE ALLOWING FOR THE RELATIVELY HIGHER VISIBILITIES IN THE
1-2SM RANGE. THIS WILL CHANGE AS WINDS INCREASE AND SNOW
INTENSITIES INCREASE. DETERMINISTIC NAM AND GFS RUNS STILL BULLISH
ON QPF...SO THE CURRENT FORECAST IS A GOOD MIX OF NEAR TERM HI-RES
GUIDANCE...INCLUDING LOCAL VERSION OF THE VARIOUS WRF MEMBERS AND
ESPC THE HRRR WHICH HAS DONE WELL W/ INITIALIZING OVER THE FIRST
PART OF THIS EVENT.
DAYBREAK THROUGH MIDDAY...
IF THEY HAVEN`T ALREADY BY DAYBREAK - CONDITIONS WILL DETERIORATE
RAPIDLY ACROSS MOST - IF NOT ALL - OF THE CWA. LOCALIZED AREAS WILL
RECEIVE BRIEF INTENSE SNOWFALL RATES OF 1-2 INCHES PER HR...POSSIBLY
HIGHER. NOW THAT THE LOW IS ON THE DOORSTEP AND NEAR-TERM GUIDANCE
HAS BEEN INITIALIZING W/ THIS DATA...SOME OF THE HI-RES MEMBERS HAVE
STARTED TO DEPICT ONE LARGE ENCOMPASSING SNOW BAND - ORIENTED ALONG
THE I-95 CORRIDOR BUT STRETCHING OVER THE ENTIRETY OF THE
PIEDMONT/COASTAL COUNTIES...TAPERING OFF TOWARD THE BLUE RIDGE AND
APLCNS. WITHIN THIS LARGER BAND WILL BE THE DYNAMIC HEAVIER BANDS W/
THE HIGHER INTENSITIES AND LOW VISIBILITIES.
WINDS AROUND THIS SECTOR OF THE STORM WILL BE STRENGTHENING W/ SUST
SPEEDS IN THE 15-25MPH RANGE AND PEAK GUSTS IN THE 30-40MPH RANGE.
NEAR-WHITEOUT CONDITIONS ARE STILL IN QUESTION...IN TERMS OF AREA
AND DURATION. THERE WILL BE BRIEF PERIODS OF NEAR-WHITEOUT
CONDITIONS BUT AS FAR WIDESPREAD AND LONG-LIVED DURATIONS...
CONFIDENCE IS LOWER. REGARDLESS...THE HEAVY-WET SNOW AND GUSTY WINDS
WILL CREATE DANGEROUS AND NEAR-IMPOSSIBLE TRAVEL AT TIMES.
MIDDAY THROUGH LATE TONIGHT...
THE HEIGHT OF SNOWFALL RATES AND INTENSITIES ACROSS THE I-95
CORRIDOR...THE METRO AREAS AND THE VA/MD PIEDMONT IS EXPECTED TO BE
FROM THE LATE MRNG INTO THE EARLY AFTN HRS. AT THIS TIME...THE LOW
WILL BE MOVING AWAY FROM THE OCEAN CITY MD AREA...PULLING AWAY FROM
THE COAST AND STARTING TO TAKE THE PRECIP ALONG WITH IT.
SEVERAL ADDITIONAL INCHES OF SNOW WILL ACCUMULATE ACROSS THE
REGION...BRINGING TOTALS TO LIKELY OVER A FOOT ACROSS MUCH OF THE
SHEN VLY AND BETWEEN ONE-TO-TWO FT ALONG THE SURROUNDING
RIDGELINES...JUST UNDER A FOOT ACROSS THE VA PIEDMONT AND JUST INTO
N CNTRL MD...MORE OF A 6-12 INCH SPREAD ALONG THE I-95 CORRIDOR AND
A RAIN/SNOW MIX ALONG THE WRN BAYSHORE COUNTIES AND SRN MD - THOUGH
4-8 INCH TOTAL STILL POSSIBLE AT THE TAIL END OF STORM SYSTEM
LATER IN THE AFTN/EVE.
A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE
MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE
COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY
FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE
BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY
OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW
FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER
INTO THE EARLY MRNG HRS THU.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST
TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH
FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME.
ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION
SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY
FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE
WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE
AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH
SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE
SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS
SHOWING CLEAR TO PARTLY CLOUDY SKIES.
NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN
SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY.
CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST
SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC
HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND
CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S
WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR
I-95.
EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES
SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE.
GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL
WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS
COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
A SNOWSTORM FOR MUCH OF THE AREA TODAY. THE PAST SEVERAL HRS HAS
BEEN THE WARM-UP FOR THE MORE INTENSE VERSION LATER THIS MRNG AND
AFTN. SOLID IFR CONDS ALREADY COVERING THE REGION W/ A FEW LIFR OBS
SCATTERED ABOUT...UNDER THE HEAVIER SNOW BANDS. THE RESPONSIBLE SFC
LOW IS STILL OVER ERN NC BUT WILL MOVE TOWARD THE NORFOLK VA AREA IN
THE COMING HRS...INTENSIFY AND CREATE A STRONGER LOW LEVEL WIND
FIELD BACK ACROSS MD/NRN VA. INTENSE SNOWFALL RATES...GUSTY WINDS
AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK
TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD
THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE
EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND
INTO THU.
PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN
TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY
NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH
PRESSURE THIS WEEKEND.
&&
.MARINE...
GALE FORCE WIND GUSTS WILL BECOME MORE COMMON HEADING INTO THE MRNG
HRS TODAY...AS A SFC LOW MOVES FROM NRN NC TOWARD THE DELMARVA
REGION. BREEZY E-NELY WINDS WILL BECOME INTENSE NLY WINDS WHILE THE
LOW IS MOVING OFF THE COAST LATER THIS MRNG. SOLID GALE GUSTS WILL
STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL
CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE
GALE RANGE OVERNIGHT.
WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT
HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA
CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK.
&&
.HYDROLOGY...
MODEL GUIDANCE REMAINS REMARKABLY CONSISTENT WITH A QPF BULLSEYE IN
THE RAPPAHANNOCK BASIN. AROUND TWO INCHES OF LIQUID/LIQUID EQUIV
PRECIPITATION IS LIKELY THROUGH MUCH OF THAT BASIN. IT LOOKS LIKE
THE MAJORITY OF THAT WILL WIND UP BEING FROM SNOW ESPECIALLY IN
THE UPPER PART. IN ADDITION...SFC TEMPS AND SOIL TEMPS ARE AND
WILL REMAIN ABOVE FREEZING OUTSIDE THE HIGHER ELEVATIONS...SO
THERE WILL BE SOME SOIL INFILTRATION INITIALLY FROM RAIN...LIQUID
FROM SNOW...OR BOTH. THEN WE HAVE TO LOOK AT HOW QUICKLY THE SNOW
MELTS...AND HOW LONG IT TAKES TO START MELTING THE MOUNTAIN SNOWS
TO ADD TO THE PICTURE. THE MOST LIKELY SCENARIO IS FOR THERE TO BE
A GRADUAL MELT...WHICH WOULD NOT POSE MUCH OF A FLOOD THREAT...BUT
THE AFOREMENTIONED UNCERTAINTIES LEND THEMSELVES TO KEEPING AN EYE
ON THE SITUATION THROUGH THE END OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
ANOMALIES HAVE TURNED POSITIVE...CLOSE TO 1 FT ABOVE NORMAL AT 3 AM
ALONG THE WESTERN SHORE OF THE BAY. WITH EASTERLY FLOW PERSISTING
THIS MORNING...ANOMALIES WILL CONTINUE TO CLIMB POSSIBLY ON THE
ORDER OF 1.5 TO 2 FT ABOVE NORMAL. THIS WILL PRODUCE MINOR TIDAL
FLOODING ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY UP THROUGH AT
LEAST ANNE ARUNDEL COUNTY...AND CONFIDENCE IS INCREASING OF THE
MINOR THRESHOLD BEING REACHED TOWARD BALTIMORE DURING HIGH TIDE.
CONFIDENCE DECREASES NORTH OF HERE WITH AN EAST WIND BECOMING
NORTHEAST BY HIGH TIDE TIME. SAME GOES FOR THE UPPER TIDAL
POTOMAC...SO WILL REFRAIN FROM ADVISORY IN THESE AREAS DO TO LOWER
CONFIDENCE BUT WILL NEED TO BE WATCHED.
LATER THIS AFTERNOON AND EVENING WHEN WINDS DO TURN
NORTHERLY...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS
COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER
IN THE UPPER BAY. FORECAST MODEL SHOWS A LITTLE WATER TRAPPING IN
THE LOWERMOST TIDAL POTOMAC THAT KEEPS LEVELS ELEVATED FOR THE
WEDNESDAY EVENING CYCLE THERE. WILL HAVE TO KEEP AN EYE ON THAT.
WINDS TURN OUT OF THE NORTHWEST AFTER THAT...WHICH SHOULD MAKE
EVERYTHING DROP SIGNIFICANTLY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001.
MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501-
502.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007-
009>011-013-014-016>018.
COASTAL FLOOD ADVISORY FROM 7 AM THIS MORNING TO 2 PM EST THIS
AFTERNOON FOR MDZ014-017-018.
COASTAL FLOOD ADVISORY FROM 11 AM THIS MORNING TO 4 PM EST
THIS AFTERNOON FOR MDZ011.
VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031-
503-504.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040-
042-050>057-501-502.
WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053-
055-501>506.
MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535-
536.
GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536.
&&
$$
SYNOPSIS...BPP/GMS
NEAR TERM...GMS
SHORT TERM...BPP
LONG TERM...JRK
AVIATION...JRK/BPP/GMS
MARINE...JRK/BPP/GMS
HYDROLOGY...BPP/JE
TIDES/COASTAL FLOODING...BPP/JE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
341 AM EST WED MAR 6 2013
.UPDATE...
ISSUED AT 340 AM EST WED MAR 6 2013
QUICK UPDATE THIS MORNING CONCERNING FREEZING DRIZZLE ACROSS THE
NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP
TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS
BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR
OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS
MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION
THROUGH THE MORNING COMMUTE.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS SHORTWAVE
DROPPING SE INTO THE MID MISSISSIPPI VALLEY. WAVE IS BEING FORCED SE
BY MID LEVEL HIGH OVER QUEBEC. AS A RESULT...SYSTEM SNOW HAS PAST BY
TO THE W AND S OF UPPER MI TODAY. SOME VERY LIGHT LES IS OCCURRING
IN E TO NE FLOW ACROSS LAKE SUPERIOR INTO THE KEWEENAW AND NCNTRL
UPPER MI AS TEMPS AT THE BASE OF A LOW 3KFT INVERSION ARE JUST
SUFFICIENT FOR LES AT -11C. UNDER DOWNSLOPING E TO NE LOW-LEVEL
WINDS...THE ERN FCST AREA HAS ENJOYED A SUNNY DAY TODAY.
VIGOROUS SHORTWAVE/MID LEVEL LOW OVER THE MID MISSISSIPPI VALLEY
WILL MOVE TO VCNTY OF NC BY WED MORNING AND WILL HAVE LITTLE IMPACT
ON WEATHER HERE. WHAT WILL BE A FACTOR IS A NRN STREAM SHORTWAVE
THAT WILL BE DRIFTING INTO THE UPPER LAKES LATE TONIGHT/WED...
BRINGING A DECENT AREA OF DEEP LAYER FORCING PER QVECTORS. THE
APPROACHING SHORTWAVE WILL HELP SHARPEN LOW-LEVEL CYCLONIC N TO NE
FLOW ACROSS LAKE SUPERIOR TONIGHT/WED MORNING BEFORE WINDS SHIFT NW
WED AS THE WAVE REACHES THE AREA. WHILE LOW-LEVEL THERMAL PROFILE
CHANGES VERY LITTLE...OVERWATER INSTABILITY IS MORE THAN SUFFICIENT
FOR LAKE ENHANCEMENT...AND THE FACT THAT SOME VERY LIGHT LES IS
ALREADY OCCURRING SUGGESTS THERE SHOULD BE A DECENT UPTICK IN LES
TONIGHT/WED MORNING. WITH ALL MODEL GUIDANCE SHOWING A SSE TO NNW
ORIENTED SFC TROF DEVELOPING ACROSS ROUGHLY CNTRL LAKE SUPERIOR...IT
WOULD APPEAR THAT NW AND NCNTRL UPPER MI SHOULD BE FAVORED FOR MORE
PERSISTENT SNOW. SNOW TO WATER RATIOS SHOULD BE ON THE LOW SIDE
10-15 TO 1...EXCEPT IN THE VCNTY/ALONG THE AFORENTIONED SFC TROF
WHERE DEEPER VERTICAL MOTION...THOUGH NOT STRONG...SHOULD INTERSECT
THE DGZ AND POSSIBLY BOOST RATIOS TOWARD 20 TO 1. AT THIS POINT...IT
APPEARS ACCUMULATIONS UPWARDS OF AROUND 3 INCHES ARE POSSIBLE OVER
NW/NCNTRL HIGHER TERRAIN TONIGHT/WED MORNING. ACCUMULATIONS SHOULD
BE A LITTLE LESS FARTHER W TOWARD KIWD. IT REALLY WON`T BE UNTIL
LATER WED MORNING/AFTN WHEN SFC TROF PASSES THAT SNOW REACHES THE NE
FCST AREA. AWAY FROM LAKE ENHANCEMENT...EXPECT SOME -SN/-SHSN TIED
TO SHORT PERIOD OF STRONGER FORCING ASSOCIATED WITH SHORTWAVE. -SHSN
WILL DIMINISH W TO E WED AFTN AND MAY END OVER THE W.
TEMPS TONIGHT ARE FAIRLY STRAIGHTFORWARD WITH CLOUD COVER LIMITING
TEMP FALL. ONE EXCEPTION IS THE ERN FCST AREA AS IT`S UNCERTAIN WHEN
CLOUDS WILL INCREASE SUFFICIENTLY TO SLOW/STOP TEMP FALL THERE
TONIGHT. GIVEN THAT IT`S SUNNY IN THAT AREA NOW...AND SATELLITE
IMAGERY SHOWS NO TREND TO CLOUD UP SOON...TEMPS COULD PLUMMET
QUICKLY THIS EVENING. FCST WILL SHOW MINS IN THE MID TEENS...BUT
IT`S QUITE POSSIBLE TEMPS COULD FALL WELL DOWN INTO THE SINGLE
DIGITS DURING THE EVENING IF IT REMAINS MOSTLY CLEAR. MID 20S TO LWR
30S SHOULD BE THE RULE WED.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
LINGERING SURFACE TROUGH AND NORTHERN STREAM SHORTWAVE WILL BE
SLIDING EAST ACROSS EASTERN LAKE SUPERIOR ON WEDNESDAY EVENING WHILE
AN AREA OF HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES. WITH
900MB TEMPS STILL AROUND -12C AND ENOUGH LOW LEVEL MOISTURE BELOW
THE 3-4KFT INVERSION...SHOULD STILL SEE LOW CLOUDS ACROSS THE AREA
DURING THE EVENING IN THE NORTH-NORTHWEST WIND LOCATIONS. DURING THE
EVENING...WOULD EXPECT ISOLATED/SCATTERED SNOW SHOWERS IN THOSE SAME
WIND FAVORED LOCATIONS. WITH A LITTLE DEEPER MOISTURE OVER THE
EASTERN LOCATIONS...MAINLY FROM MUNISING EASTWARD...WOULD EXPECT
ISOLATED LIGHT SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT. OVER THE
WEST...THE INFLUENCE OF THE HIGH WILL ALLOW THE FLOW TO BECOME
ANTI-CYCLONIC THROUGH THE NIGHT AND INCREASE THE DRY AIR OVER THE
WESTERN LAKE...SLOWLY DECREASING THE CLOUDS IN THAT AREA. THIS
DECREASE IN CLOUDS LEADS TO UNCERTAINTY IN THE LOWS OVER THE WESTERN
CWA. WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF
NORMAL...LOCATIONS THAT DO CLEAR OUT WILL LIKELY FALL INTO THE
SINGLE DIGITS AND WOULDN/T BE SURPRISED TO SEE A FEW BELOW ZERO
READINGS IN THE COLD SPOTS OF EASTERN GOGEBIC AND IRON COUNTY.
THE HIGH WILL CONTINUE TO MOVE OVER THE AREA ON THURSDAY...CAUSING
WINDS TO BECOME MORE VARIABLE. WITH THE STRENGTHENING SUBSIDENCE
INVERSION...THE QUESTION FOR THURSDAY WILL BE WHERE THE CLOUDS WILL
BE LOCATED AND IF/WHEN THEY WILL MIX OUT. WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING WILL LIKELY EAT AWAY AT THE CLOUDS.
UPPER RIDGE BUILDS OVER THE AREA ON THURSDAY NIGHT INTO
FRIDAY...WHICH WILL KEEP THE AREA DRY AND ONLY PRODUCE SOME
MID-HIGH CLOUDS STREAMING ACROSS THE AREA. BY FRIDAY NIGHT...AN
UPPER TROUGH WILL BE SITTING OVER THE SOUTHWEST CONUS AND A
NORTHERN STREAM TROUGH WILL BE MOVING THROUGH
MANITOBA/SASKATCHEWAN. THE QUESTION BECOMES WHETHER THESE TWO
TROUGHS WILL SEPARATE OR STAY TOGETHER...WHICH THEN INFLUENCES THE
FORECAST INTO THE FIRST PART OF NEXT WEEK. THE LATEST TRENDS IN THE
12Z MODEL RUNS IS TO KEEP THE WAVES PHASED ENOUGH THROUGH THE
WEEKEND DUE TO A STRONGER NORTHERN STREAM WAVE. THIS IN TURN LEADS
TO STRONGER FORCING WITH THE SURFACE TROUGH MOVING THROUGH SATURDAY
INTO SATURDAY EVENING. WITH THIS STRONGER WAVE AND INCREASED
SOUTHERLY FLOW AHEAD OF THE SYSTEM...MODELS HAVE TRENDED UP WITH
THE QPF...ESPECIALLY OVER THE WESTERN HALF OF THE CWA. HAVE TRENDED
POPS UP FOR THIS PERIOD AND WITH SOME OF THE QPF AMOUNTS SHOWN ON
THE 12Z RUNS...COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS
OVER WESTERN UPPER MICHIGAN. WON/T MENTION THIS IN THE HWO AT THIS
POINT WITH THE WAY THE MODELS HAVE BEEN VARYING...BUT WILL BE
SOMETHING TO WATCH. FINALLY...LOOKING AT MODEL SOUNDINGS...THEY TRY
TO NOSE TEMPS ABOVE 0C AROUND 850MB OVER THE SOUTH CENTRAL WHICH
COULD LEAD TO SOME MELTING ALONG THE ISOTHERMAL LAYER TO THE
SURFACE. THUS...ADDED A MIX OF RAIN/SNOW TO THAT AREA.
HIGH PRESSURE WILL LIKELY BUILD INTO THE UPPER GREAT LAKES FOR
SUNDAY AND THE FIRST PART OF MONDAY...BEFORE THE NEARLY
CLOSED SOUTHERN STREAM TROUGH DRIFTS OUT OF THE SOUTHWEST CONUS.
WHILE THIS SYSTEM WAS LOOKING LIKE IT WAS GOING TO MOVE TOWARDS THE
UPPER GREAT LAKES ON THE 12Z RUNS YESTERDAY...THE LATEST TRENDS
HAVE IT MOVING MORE THROUGH THE OHIO RIVER VALLEY. THEREFORE...HAVE
TRENDED POPS DOWN FOR THE MONDAY PERIOD AND IF THE TREND CONTINUES
THEY MAY NEED TO BE REMOVED COMPLETELY.
AS FOR TEMPERATURES DURING THE LONG TERM PERIOD...IT LOOKS TO BE
FAIRLY NORMAL WITH A FEW DAYS OF SLIGHTLY ABOVE NORMAL HIGHS
THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1235 AM EST WED MAR 6 2013
DRY AIR CONTINUES TO DELAY THINGS AND PUSHED THE TIMING BACK A BIT.
WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED
MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS
FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS OVERNIGHT WITH -SHSN
DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR BY MORNING UNDER
FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR
OVERNIGHT BEFORE FALLING TO PREVAILING IFR BY MORNING. AT
KSAW...MVFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP LATE TONIGHT.
FAVORABLE CONVERGENT UPSLOPE FLOW WED MORNING WILL RESULT IN CIGS
FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER WED
MORNING INTO THE EARLY AFTERNOON WHERE MVFR CONDITIONS WILL THEN
PREVAIL.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EST TUE MAR 5 2013
NE TO N WINDS OF 15-25KT WILL BE THE RULE ACROSS LAKE SUPERIOR
TONIGHT...THOUGH 20-30KT WINDS WILL LINGER OVER THE WRN PORTION OF
THE LAKE INTO THE EVENING HRS BEFORE PRES GRADIENT BEGINS TO RELAX.
WINDS WILL FALL OFF TO UNDER 20KT OVER WRN LAKE SUPERIOR WED. OVER
ERN LAKE SUPERIOR...TIGHTER PRES GRADIENT WILL ALLOW 15-25KT WINDS
TO PERSIST INTO EARLY THU MORNING. HIGH PRES RIDGE PASSING OVER THE
AREA WILL THEN LEAD TO WINDS UNDER 20KT ACROSS THE LAKE THU/FRI.
ALTHOUGH A LOW PRES TROF WILL PASS ACROSS LAKE SUPERIOR LATER
SAT/EARLY SUN...PRES GRADIENT REMAINS WEAK...KEEPING WINDS MOSTLY
UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...TK
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1236 AM EST WED MAR 6 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS SHORTWAVE
DROPPING SE INTO THE MID MISSISSIPPI VALLEY. WAVE IS BEING FORCED SE
BY MID LEVEL HIGH OVER QUEBEC. AS A RESULT...SYSTEM SNOW HAS PAST BY
TO THE W AND S OF UPPER MI TODAY. SOME VERY LIGHT LES IS OCCURRING
IN E TO NE FLOW ACROSS LAKE SUPERIOR INTO THE KEWEENAW AND NCNTRL
UPPER MI AS TEMPS AT THE BASE OF A LOW 3KFT INVERSION ARE JUST
SUFFICIENT FOR LES AT -11C. UNDER DOWNSLOPING E TO NE LOW-LEVEL
WINDS...THE ERN FCST AREA HAS ENJOYED A SUNNY DAY TODAY.
VIGOROUS SHORTWAVE/MID LEVEL LOW OVER THE MID MISSISSIPPI VALLEY
WILL MOVE TO VCNTY OF NC BY WED MORNING AND WILL HAVE LITTLE IMPACT
ON WEATHER HERE. WHAT WILL BE A FACTOR IS A NRN STREAM SHORTWAVE
THAT WILL BE DRIFTING INTO THE UPPER LAKES LATE TONIGHT/WED...
BRINGING A DECENT AREA OF DEEP LAYER FORCING PER QVECTORS. THE
APPROACHING SHORTWAVE WILL HELP SHARPEN LOW-LEVEL CYCLONIC N TO NE
FLOW ACROSS LAKE SUPERIOR TONIGHT/WED MORNING BEFORE WINDS SHIFT NW
WED AS THE WAVE REACHES THE AREA. WHILE LOW-LEVEL THERMAL PROFILE
CHANGES VERY LITTLE...OVERWATER INSTABILITY IS MORE THAN SUFFICIENT
FOR LAKE ENHANCEMENT...AND THE FACT THAT SOME VERY LIGHT LES IS
ALREADY OCCURRING SUGGESTS THERE SHOULD BE A DECENT UPTICK IN LES
TONIGHT/WED MORNING. WITH ALL MODEL GUIDANCE SHOWING A SSE TO NNW
ORIENTED SFC TROF DEVELOPING ACROSS ROUGHLY CNTRL LAKE SUPERIOR...IT
WOULD APPEAR THAT NW AND NCNTRL UPPER MI SHOULD BE FAVORED FOR MORE
PERSISTENT SNOW. SNOW TO WATER RATIOS SHOULD BE ON THE LOW SIDE
10-15 TO 1...EXCEPT IN THE VCNTY/ALONG THE AFORENTIONED SFC TROF
WHERE DEEPER VERTICAL MOTION...THOUGH NOT STRONG...SHOULD INTERSECT
THE DGZ AND POSSIBLY BOOST RATIOS TOWARD 20 TO 1. AT THIS POINT...IT
APPEARS ACCUMULATIONS UPWARDS OF AROUND 3 INCHES ARE POSSIBLE OVER
NW/NCNTRL HIGHER TERRAIN TONIGHT/WED MORNING. ACCUMULATIONS SHOULD
BE A LITTLE LESS FARTHER W TOWARD KIWD. IT REALLY WON`T BE UNTIL
LATER WED MORNING/AFTN WHEN SFC TROF PASSES THAT SNOW REACHES THE NE
FCST AREA. AWAY FROM LAKE ENHANCEMENT...EXPECT SOME -SN/-SHSN TIED
TO SHORT PERIOD OF STRONGER FORCING ASSOCIATED WITH SHORTWAVE. -SHSN
WILL DIMINISH W TO E WED AFTN AND MAY END OVER THE W.
TEMPS TONIGHT ARE FAIRLY STRAIGHTFORWARD WITH CLOUD COVER LIMITING
TEMP FALL. ONE EXCEPTION IS THE ERN FCST AREA AS IT`S UNCERTAIN WHEN
CLOUDS WILL INCREASE SUFFICIENTLY TO SLOW/STOP TEMP FALL THERE
TONIGHT. GIVEN THAT IT`S SUNNY IN THAT AREA NOW...AND SATELLITE
IMAGERY SHOWS NO TREND TO CLOUD UP SOON...TEMPS COULD PLUMMET
QUICKLY THIS EVENING. FCST WILL SHOW MINS IN THE MID TEENS...BUT
IT`S QUITE POSSIBLE TEMPS COULD FALL WELL DOWN INTO THE SINGLE
DIGITS DURING THE EVENING IF IT REMAINS MOSTLY CLEAR. MID 20S TO LWR
30S SHOULD BE THE RULE WED.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 407 PM EST TUE MAR 5 2013
LINGERING SURFACE TROUGH AND NORTHERN STREAM SHORTWAVE WILL BE
SLIDING EAST ACROSS EASTERN LAKE SUPERIOR ON WEDNESDAY EVENING WHILE
AN AREA OF HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES. WITH
900MB TEMPS STILL AROUND -12C AND ENOUGH LOW LEVEL MOISTURE BELOW
THE 3-4KFT INVERSION...SHOULD STILL SEE LOW CLOUDS ACROSS THE AREA
DURING THE EVENING IN THE NORTH-NORTHWEST WIND LOCATIONS. DURING THE
EVENING...WOULD EXPECT ISOLATED/SCATTERED SNOW SHOWERS IN THOSE SAME
WIND FAVORED LOCATIONS. WITH A LITTLE DEEPER MOISTURE OVER THE
EASTERN LOCATIONS...MAINLY FROM MUNISING EASTWARD...WOULD EXPECT
ISOLATED LIGHT SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT. OVER THE
WEST...THE INFLUENCE OF THE HIGH WILL ALLOW THE FLOW TO BECOME
ANTI-CYCLONIC THROUGH THE NIGHT AND INCREASE THE DRY AIR OVER THE
WESTERN LAKE...SLOWLY DECREASING THE CLOUDS IN THAT AREA. THIS
DECREASE IN CLOUDS LEADS TO UNCERTAINTY IN THE LOWS OVER THE WESTERN
CWA. WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF
NORMAL...LOCATIONS THAT DO CLEAR OUT WILL LIKELY FALL INTO THE
SINGLE DIGITS AND WOULDN/T BE SURPRISED TO SEE A FEW BELOW ZERO
READINGS IN THE COLD SPOTS OF EASTERN GOGEBIC AND IRON COUNTY.
THE HIGH WILL CONTINUE TO MOVE OVER THE AREA ON THURSDAY...CAUSING
WINDS TO BECOME MORE VARIABLE. WITH THE STRENGTHENING SUBSIDENCE
INVERSION...THE QUESTION FOR THURSDAY WILL BE WHERE THE CLOUDS WILL
BE LOCATED AND IF/WHEN THEY WILL MIX OUT. WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING WILL LIKELY EAT AWAY AT THE CLOUDS.
UPPER RIDGE BUILDS OVER THE AREA ON THURSDAY NIGHT INTO
FRIDAY...WHICH WILL KEEP THE AREA DRY AND ONLY PRODUCE SOME
MID-HIGH CLOUDS STREAMING ACROSS THE AREA. BY FRIDAY NIGHT...AN
UPPER TROUGH WILL BE SITTING OVER THE SOUTHWEST CONUS AND A
NORTHERN STREAM TROUGH WILL BE MOVING THROUGH
MANITOBA/SASKATCHEWAN. THE QUESTION BECOMES WHETHER THESE TWO
TROUGHS WILL SEPARATE OR STAY TOGETHER...WHICH THEN INFLUENCES THE
FORECAST INTO THE FIRST PART OF NEXT WEEK. THE LATEST TRENDS IN THE
12Z MODEL RUNS IS TO KEEP THE WAVES PHASED ENOUGH THROUGH THE
WEEKEND DUE TO A STRONGER NORTHERN STREAM WAVE. THIS IN TURN LEADS
TO STRONGER FORCING WITH THE SURFACE TROUGH MOVING THROUGH SATURDAY
INTO SATURDAY EVENING. WITH THIS STRONGER WAVE AND INCREASED
SOUTHERLY FLOW AHEAD OF THE SYSTEM...MODELS HAVE TRENDED UP WITH
THE QPF...ESPECIALLY OVER THE WESTERN HALF OF THE CWA. HAVE TRENDED
POPS UP FOR THIS PERIOD AND WITH SOME OF THE QPF AMOUNTS SHOWN ON
THE 12Z RUNS...COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS
OVER WESTERN UPPER MICHIGAN. WON/T MENTION THIS IN THE HWO AT THIS
POINT WITH THE WAY THE MODELS HAVE BEEN VARYING...BUT WILL BE
SOMETHING TO WATCH. FINALLY...LOOKING AT MODEL SOUNDINGS...THEY TRY
TO NOSE TEMPS ABOVE 0C AROUND 850MB OVER THE SOUTH CENTRAL WHICH
COULD LEAD TO SOME MELTING ALONG THE ISOTHERMAL LAYER TO THE
SURFACE. THUS...ADDED A MIX OF RAIN/SNOW TO THAT AREA.
HIGH PRESSURE WILL LIKELY BUILD INTO THE UPPER GREAT LAKES FOR
SUNDAY AND THE FIRST PART OF MONDAY...BEFORE THE NEARLY
CLOSED SOUTHERN STREAM TROUGH DRIFTS OUT OF THE SOUTHWEST CONUS.
WHILE THIS SYSTEM WAS LOOKING LIKE IT WAS GOING TO MOVE TOWARDS THE
UPPER GREAT LAKES ON THE 12Z RUNS YESTERDAY...THE LATEST TRENDS
HAVE IT MOVING MORE THROUGH THE OHIO RIVER VALLEY. THEREFORE...HAVE
TRENDED POPS DOWN FOR THE MONDAY PERIOD AND IF THE TREND CONTINUES
THEY MAY NEED TO BE REMOVED COMPLETELY.
AS FOR TEMPERATURES DURING THE LONG TERM PERIOD...IT LOOKS TO BE
FAIRLY NORMAL WITH A FEW DAYS OF SLIGHTLY ABOVE NORMAL HIGHS
THROUGH THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1235 AM EST WED MAR 6 2013
DRY AIR CONTINUES TO DELAY THINGS AND PUSHED THE TIMING BACK A BIT.
WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED
MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS
FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS OVERNIGHT WITH -SHSN
DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR BY MORNING UNDER
FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR
OVERNIGHT BEFORE FALLING TO PREVAILING IFR BY MORNING. AT
KSAW...MVFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP LATE TONIGHT.
FAVORABLE CONVERGENT UPSLOPE FLOW WED MORNING WILL RESULT IN CIGS
FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER WED
MORNING INTO THE EARLY AFTERNOON WHERE MVFR CONDITIONS WILL THEN
PREVAIL.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EST TUE MAR 5 2013
NE TO N WINDS OF 15-25KT WILL BE THE RULE ACROSS LAKE SUPERIOR
TONIGHT...THOUGH 20-30KT WINDS WILL LINGER OVER THE WRN PORTION OF
THE LAKE INTO THE EVENING HRS BEFORE PRES GRADIENT BEGINS TO RELAX.
WINDS WILL FALL OFF TO UNDER 20KT OVER WRN LAKE SUPERIOR WED. OVER
ERN LAKE SUPERIOR...TIGHTER PRES GRADIENT WILL ALLOW 15-25KT WINDS
TO PERSIST INTO EARLY THU MORNING. HIGH PRES RIDGE PASSING OVER THE
AREA WILL THEN LEAD TO WINDS UNDER 20KT ACROSS THE LAKE THU/FRI.
ALTHOUGH A LOW PRES TROF WILL PASS ACROSS LAKE SUPERIOR LATER
SAT/EARLY SUN...PRES GRADIENT REMAINS WEAK...KEEPING WINDS MOSTLY
UNDER 20KT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...07
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
345 AM CST WED MAR 6 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 332 AM CST WED MAR 6 2013
STILL SEEING SOME WEAK BANDING ON RADAR THIS MORNING THAT IS
CORRESPONDING WITH THE FLURRIES BEING REPORTED IN THE SURFACE
OBSERVATIONS. THIS BANDING LOOKS TO BE SET UP UNDER THE CHANNELED
VORT MAX ON THE WESTERN SIDE OF THE VORT. RAP DEPICTS THAT THIS
VORT WILL MOVE EAST OF THE AREA BY LATE MORNING...SO WILL MAINTAIN
SCT FLURRIES OVER THE EASTERN HALF OF THE CWA THROUGH MID MORNING.
SATELLITE STILL SHOWS EXTENSIVE CLOUDINESS OVER MO/IL EARLY THIS
MORNING...WITH THE BACK EDGE OF THE CLOUDINESS MOVING A BIT TO THE
WEST OVER WESTERN MO/EASTERN KS THE PAST FEW HOURS. THERE HAS BEEN
SOME BREAKS SEEN OVER EASTERN IA WHICH IS COMPLICATING THE CLOUD
FORECAST...THOUGH THESE BREAKS MAY FILL BACK IN DURING THE DAY AS
MOIST LOW LEVEL CYCLONIC FLOW REMAINS OVER THE AREA. IT WILL TAKE
MOST OF THE DAY BEFORE THE LOW LEVEL RIDGE CAN MOVE EAST INTO THE
AREA...SO INCREASED CLOUD COVER FOR THE DAY. CONSEQUENTLY...DO NOT
EXPECT MUCH OF A TEMPERATURE RECOVERY GIVEN THE CLOUDS AND
NORTHWESTERLY FLOW OFF THE LINGERING SNOW PACK.
BRITT
&&
.LONG TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 332 AM CST WED MAR 6 2013
UNSEASONABLY COLD WEATHER IS EXPECTED TGT WITH GOOD RADIATIONAL
COOLING AS THE SKY SHOULD CLEAR OUT AND THE SFC WIND SHOULD BECOME
LIGHT AS THE SFC RIDGE AXIS WILL BE RIGHT OVER THE FORECAST AREA
BY 12Z THU. SFC DEW POINTS WILL ALSO BE QUITE LOW IN THE UPPER
TEENS TO LOWER 20S...PLUS PARTS OF NERN AND CNTRL MO AND W CNTRL
IL WILL STILL HAVE SNOW COVER. A WARMING TREND WILL BEGIN ON THU
AS AN UPPER LEVEL RIDGE OVER THE PLAINS MOVES EWD TO OVER MO BY
00Z FRI...AND THE SFC WINDS BECOME SELY OVER A PORTION OF THE
AREA AS THE SFC RIDGE MOVES EAST OF THE REGION. TEMPERATURES ON
FRI SHOULD BE AT OR ABOVE NORMAL WITH A RELATIVELY STRONG UPPER
LEVEL RIDGE OVER MO AND IL...AND SLY LOW LEVEL WINDS BRINGING
WARMER 850 MB TEMPERATURES NWD INTO OUR AREA. SHOWERS MAY MOVE
INTO PORTIONS OF NERN AND CNTRL MO AS EARLY AS SAT AS A SLY LOW
LEVEL JET BRINGS INCREASING LOW LEVEL WAA AND MOISTURE INTO THIS
AREA WELL AHEAD OF THE UPPER LEVEL LOW AND ASSOCIATED SFC LOW
MOVING EWD FROM THE SRN ROCKIES INTO THE SRN PLAINS. THE GFS MODEL
IS A LITTLE QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL.
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD MOVE INTO MUCH OF
THE FORECAST AREA ON SAT NGT. WILL LEAN TOWARD THE SLOWER
SOLUTION OF THE ECMWF MODEL WHICH HAS ABOVE NORMAL TEMPERATURES
CONTINUING ON SUN WITH THE COLD FRONT MOVING ONLY SLOWLY SEWD
THROUGH OUR AREA AS THE UPPER LEVEL LOW REMAINS CLOSED OFF AND W OF
OUR AREA. COLDER AIR SHOULD ADVECT SEWD INTO THE REGION SUN NGT
BEHIND THE SFC LOW AND TRAILING COLD FRONT WITH THE RAIN POSSIBLY
CHANGING TO SNOW ACROSS PORTIONS OF NERN AND CNTRL MO AS WELL AS W
CNTRL IL. COLDER...BELOW NORMAL TEMPERATURES SHOULD OCCUR ON
MONDAY WITH LINGERING SNOW POSSIBLE AS THE UPPER LEVEL LOW/TROUGH
AND ASSOCIATED SFC LOW SHIFT E OF OUR AREA WITH STRONG CAA LIKELY
ON THE BACKSIDE.
GKS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1150 PM CST TUE MAR 5 2013
ABUNDANT HI-END MVFR/LO-END VFR CIGS COVERING THE ENTIRE BI-STATE
REGION AND SHOW NO SIGN OF ABATEMENT. SOME BREAKS HAVE DEVELOPED
WAY UPSTREAM IN NERN IA AND MN...BUT WILL TAKE QUITE SOME TIME TO
WORK DOWN INTO OUR AREA AND CLOUDS HAVE SHOWN SIGNS OF ATTEMPTING
TO FILL THESE BREAKS OVER THE PAST COUPLE HOURS...SO FOR NOW WILL
KEEP LO CIGS GOING CENTERED AROUND 3KFT. THESE CLOUDS SHOULD STICK
WITH US THRU MUCH OF THE DAY ON WEDNESDAY BEFORE FINALLY BREAKING
UP OR MOVING OFF TO THE E WITH ADVANCE OF SFC RIDGE WEDNESDAY
EVENING. LAST GASP OF SNOW MOVING THRU STL METRO AND APPEARS IT
MAY BE WITH US FOR A FEW MORE HOURS SO HAVE EXTENDED MENTION THRU
09Z. OTHERWISE...NW GUSTY SFC WINDS WILL ALSO SLOWLY DIMINISH BUT
MAY NOT GET COMPLETELY LOST UNTIL LATE WEDNESDAY MORNING.
SPECIFICS FOR KSTL...CIGS CENTERED AROUND 3KFT WILL BE THE RULE
THRU WEDNESDAY AFTERNOON BEFORE BREAKING UP OR MOVING OFF TO THE E
EARLY WEDNESDAY EVENING...VSBY DROPS FROM SNOW SHOULD BE MINIMAL
FROM HERE ON OUT AND ONLY HAVE TO 5SM IN TAF THRU 09Z...NW GUSTY
SFC WNDS WILL DIMINISH LATE.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1150 PM CST TUE MAR 5 2013
.UPDATE...
ISSUED AT 640 PM CST TUE MAR 5 2013
THE GOING FORECAST LOOKS TO BE GENERALLY ON TRACK. HAVE MADE A FEW
UPDATES TO BUMP POPS UP THIS EVENING AS THE BAND OF SNOW CURRENTLY
JUST SOUTH OF THE STL METRO. OTHER THAN THAT...HAVE ADDED IN
CHANCE FOR FLURRIES EVERYWHERE FOR THE OVERNIGHT AS THE RUC KEEPS
AN ELONGATED BAND OF VORTICITY OVER THE AREA AND LITTLE POCKETS OF
FRONTOGENESIS. EXPLICIT MODELS ALSO SHOW SOME LIGHT PRECIPITATION
CONTINUING TO ROTATE AROUND THE UPPER SYSTEM AS WELL.
CARNEY
&&
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 322 PM CST TUE MAR 5 2013
WITH LITTLE IN THE WAY OF ADDITIONAL SN EXPECTED THRU
TONIGHT...WILL CANCEL THE ADVISORY SOON.
AREA OF SN MOVING INTO NWRN PORTIONS OF THE CWA JUST AHEAD OF THE
UPPER LOW. THIS SN WILL CONTINUE TO MOVE SEWD INTO THE EVENING
HOURS. AN ADDITIONAL HALF INCH...MAYBE UP TO AN INCH...CAN BE
EXPECTED. WITH CLOUDS EXPECTED TO PERSIST THRU TONIGHT...HAVE
TEMPS LOWER SLIGHTLY OVERNIGHT.
WINDS WILL CONTINUE TO BE STRONG WITH GUSTS IN THE 20 TO 30 KT
RANGE INTO THE EVE. CAN NOT RULE OUT A COUPLE OF SITES BRIEFLY
REACHING WIND ADV CRITERIA...BUT EXPECT WINDS TO STAY BELOW
CRITERIA.
&&
.LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 240 PM CST TUE MAR 5 2013
(WEDNESDAY THROUGH THURSDAY)
CYCLONIC FLOW WILL CONTINUE ACROSS THE REGION THROUGH MIDDAY
WEDNESDAY IN THE WAKE OF THE DEPARTING SYSTEM. BELIEVE THERE WILL
BE QUITE A BIT OF RESIDUAL STRATUS AT DAYBREAK...AND WHILE THIS
WILL CLEAR/DECREASE SOUTHEASTWARD DURING THE MORNING/EARLY
AFTERNOON...THERE WILL ALSO BE A TENDENCY FOR ADDITIONAL STRATOCU
TO DEVELOP WITH HEATING. WITH THIS IN MIND I HAVE SHADED MY
TEMPERATURES TOWARDS THE COOLER MET GUIDANCE. IT WILL ALSO REMAIN
BREEZY ACROSS FAR EASTERN MO INTO WESTERN ILLINOIS THROUGH THE
EARLY AFTERNOON...THEN WINDS SHOULD DIMINISH AS SURFACE HIGH
PRESSURE SETTLES INTO THE AREA. THE SURFACE HIGH/RIDGE WILL
DOMINATE THE AREA ON WEDNESDAY NIGHT LEADING TO SEASONABLY COLD
CONDITIONS. WE BEGIN THE TEMPERATURE MODERATION ON THURSDAY AS THE
SURFACE HIGH SLOWLY RETREATS TO THE EAST AND HEIGHTS ALOFT
RISE...HOWEVER HIGHS WILL STILL REMAIN BELOW AVERAGE.
(FRIDAY INTO TUESDAY)
THE WARM-UP SHOULD CONTINUE TO UNFOLD ON FRIDAY AND INTO THE
WEEKEND AS THE UPPER AIR PATTERN CONTINUES TO AMPLIFY AND THE
UPPER RIDGE BUILDS THROUGH THE MS VALLEY AND SHIFTS EASTWARD.
THERE IS BETTER AGREEMENT IN THE EVOLVING PATTERN AND HANDLING OF
THE WESTERN UPPER LOW/TROF WITH THE 12Z NWP SUITE THAN THE 00Z
GUIDANCE. THE GENERAL CONSENSUS NOW IS THE INCREASINGLY POSITIVELY
TILTED UPPER TROF WILL SHIFT INTO THE NATIONS MIDSECTION BY SUNDAY
WITH THE UPPER LOW EJECTING NEWD THROUGH THE MID MS VALLEY SUNDAY
NIGHT INTO EARLY MONDAY. THIS SHOULD BRING A GOOD RAIN THREAT TO
THE REGION LATE SATURDAY NIGHT INTO SUNDAY NIGHT. THERE ARE NOW
SOME SUGGESTIONS THAT THERE COULD BE A CHANGEOVER FROM RAIN TO
SNOW ACROSS PARTS OF NORTHERN MISSOURI LATE SUNDAY NIGHT AND
POSSIBLY POTENTIAL FOR SOME LIGHT ACCUMULATIONS...HOWEVER THE
MODELS HAVE BEEN QUITE CHAOTIC WITH THE DETAILS OF THIS SYSTEM AND
THUS CONFIDENCE IS LOW ON THIS ASPECT OF THE SYSTEM.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1150 PM CST TUE MAR 5 2013
ABUNDANT HI-END MVFR/LO-END VFR CIGS COVERING THE ENTIRE BI-STATE
REGION AND SHOW NO SIGN OF ABATEMENT. SOME BREAKS HAVE DEVELOPED
WAY UPSTREAM IN NERN IA AND MN...BUT WILL TAKE QUITE SOME TIME TO
WORK DOWN INTO OUR AREA AND CLOUDS HAVE SHOWN SIGNS OF ATTEMPTING
TO FILL THESE BREAKS OVER THE PAST COUPLE HOURS...SO FOR NOW WILL
KEEP LO CIGS GOING CENTERED AROUND 3KFT. THESE CLOUDS SHOULD STICK
WITH US THRU MUCH OF THE DAY ON WEDNESDAY BEFORE FINALLY BREAKING
UP OR MOVING OFF TO THE E WITH ADVANCE OF SFC RIDGE WEDNESDAY
EVENING. LAST GASP OF SNOW MOVING THRU STL METRO AND APPEARS IT
MAY BE WITH US FOR A FEW MORE HOURS SO HAVE EXTENDED MENTION THRU
09Z. OTHERWISE...NW GUSTY SFC WINDS WILL ALSO SLOWLY DIMINISH BUT
MAY NOT GET COMPLETELY LOST UNTIL LATE WEDNESDAY MORNING.
SPECIFICS FOR KSTL...CIGS CENTERED AROUND 3KFT WILL BE THE RULE
THRU WEDNESDAY AFTERNOON BEFORE BREAKING UP OR MOVING OFF TO THE E
EARLY WEDNESDAY EVENING...VSBY DROPS FROM SNOW SHOULD BE MINIMAL
FROM HERE ON OUT AND ONLY HAVE TO 5SM IN TAF THRU 09Z...NW GUSTY
SFC WNDS WILL DIMINISH LATE.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
354 AM CST WED MAR 6 2013
.DISCUSSION...
MAIN FORECAST CONCERN TODAY WILL BE THE EXTENT OF LOW CLOUDS AND
THE RESULTING AFFECT ON TEMPERATURES. THEN FOCUS TURNS TO SYSTEM
MOVING INTO THE PLAINS FOR THE WEEKEND.
AN EXPANSIVE AREA OF STRATUS CONTINUES TO MOVES SOUTH FROM THE
EASTERN DAKOTAS AND CURRENTLY COVERS MOST OF THE CWA EXCEPT THE
EXTREME WESTERN COUNTIES. THE RAP SEEMS TO HAVE THE BEST HANDLE
ON THESE CLOUDS AND WILL JUMP ON BOARD WITH THIS
GUIDANCE...KEEPING CLOUD COVER THROUGH AT LEAST 18Z OVER A
MAJORITY OF THE CWA. A SFC HIGH PRESSURE RIDGE CURRENTLY OVER
CENTRAL NEBRASKA WILL CONTINUE TO BUILD EAST AND INHIBIT MIXING
TO SCOUR OUT CLOUDS. THEREFORE THE RAP IDEA OF HANGING ONTO THE
CLOUDS SEEMS FAIR THROUGH MUCH OF THE MORNING HOURS AND POSSIBLY
INTO THE AFTERNOON IN OUR EAST. AS SOUTHERLY LOW LEVEL FLOW
INCREASES LATE THIS AFTERNOON...EXPECT CLOUDS TO MOVE OUT FROM
WEST TO EAST. HAVE REDUCED HIGHS TO A FEW DEGREES BELOW MOS DUE TO
CLOUD COVER.
QUIET CONDITIONS AND A GRADUAL WARMING TREND ARE EXPECTED TODAY
THROUGH FRIDAY AS AN UPPER RIDGE PASSES OVER THE CENTRAL CONUS
THROUGH THIS TIME PERIOD. HIGH TEMPS SHOULD BE IN THE UPPER 40S
AND LOWER 50S BY FRIDAY.
FOCUS TURNS TO LARGE SYSTEM CURRENTLY OFF THE PACIFIC NORTHWEST
COAST. THIS IS FORECAST TO ROUND THE FOUR CORNERS REGION BY
SATURDAY 12Z. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON
PLACEMENT AND TIMING LEADING TO INCREASING FORECASTER CONFIDENCE.
A LEAD SHORTWAVE WILL EJECT INTO THE CENTRAL PLAINS BY FRIDAY
NIGHT WITH A SFC WARM FRONT EXTENDING NORTHEAST AND BISECTING OUR
CWA. THIS BOUNDARY SHOULD BE THE FOCUS FOR PRECIPITATION FRIDAY
NIGHT INTO SATURDAY. BETTER UPPER LEVEL DYNAMICS WILL ADVANCE
INTO THE AREA SATURDAY NIGHT INTO SUNDAY AS THE UPPER LOW KICKS
OUT OF EASTERN COLORADO AND INTO KANSAS. WILL CONTINUE LIKELY POPS
FOR THIS TIME PERIOD. TIGHT BAROCLINIC ZONE WILL REMAIN EXTENDED
ACROSS THE FORECAST AREA WITH SNOW MOST LIKELY TO THE NORTH OF THE
BOUNDARY AND RAIN IN THE SOUTH...WITH A TRANSITION ZONE SOMEWHERE
IN THE MIDDLE. MODELS HAVE BEEN CONSISTENT WITH DROPPING COLDER
AIR SOUTH OVER THE FORECAST AREA SO SNOW COULD BE PRIMARY PCPN
TYPE SAT NIGHT THROUGH SUNDAY NIGHT WHEN DEFORMATION ZONE MOVES
OVERHEAD. HAVE INCREASED THE SFC WINDS ON THE BACKSIDE OF THIS
SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH UNIDIRECTIONAL
NORTHERLY FLOW CREATING QUITE BLUSTERY CONDITIONS. 850MB WIND
SPEEDS ARE FORECAST AROUND 50 KTS OFF BOTH THE 00Z GFS AND 00Z
ECMWF. THIS SAID...IF ANY SNOW IS FALLING...IT WILL BE BLOWING
AROUND.
THIS SYSTEM QUICKLY MOVES EAST SUNDAY NIGHT ENDING PCPN FROM WEST
TO EAST LEAVING NORTHWESTERLY FLOW ALOFT. FORECAST SUB ZERO C 850
MB TEMPS IN ADDITION TO POTENTIAL SNOW COVER WOULD SUGGEST BELOW
NORMAL TEMPS EARLY NEXT WEEK.
KERN
&&
.AVIATION...06Z TAFS FOR KOMA...KLNK AND KOFK. MVFR CEILINGS WILL
LINGER AT KOMA...PERHAPS UNTIL MID TO LATE MORNING...BUT SHOULD
BEGIN TO SCATTER OUT BY 1820Z. INITIAL CLOUD LINE WAS SLOWLY
RETREATING WEST AND FINALLY HAD REACHED KOFK...AND WILL PROBABLY
REACH KLNK BY 07-08Z. BELIEVE CLOUDS COULD SCATTER AT KOFK/KLNK BY
16-18Z.
DEWALD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1117 PM CST TUE MAR 5 2013
.SYNOPSIS...
ISSUED AT 320 PM CST TUE MAR 5 2013
H5 HAND ANALYSIS THIS MORNING...INDICATES A CONTINUED ACTIVE PATTERN
ACROSS NOAM. A STRONG SHORTWAVE WAS LOCATED ACROSS NWRN MISSOURI
WITH DECENT HT FALLS NOTED FROM THE TWIN CITIES SWD INTO SWRN MO.
FURTHER WEST...A LOW AMPLITUDE RIDGE EXTENDED FROM SO CALIFORNIA NWD
TO THE IDAHO PANHANDLE. WHILE WEST OF THIS FEATURE...A TROUGH
EXTENDED FROM ERN BRITISH COLUMBIA...SWD TO A CLOSED LOW OFF THE
COAST OF OREGON. ACROSS THE EASTERN CONUS...A CLOSED LOW WAS PRESENT
OVER THE CANADIAN MARITIMES WITH HIGH PRESSURE NOTED OVER NRN
QUEBEC. AT THE SURFACE...HIGH PRESSURE HAS BUILT INTO WESTERN
NEBRASKA THIS AFTERNOON RESULTING IN LIGHT WINDS. FURTHER
EAST...BREEZY CONDITIONS CONTINUED. TEMPERATURES AS OF 3 PM CST
RANGED FROM 32 AT O`NEILL TO 41 AT OGALLALA.
&&
.UPDATE...
ISSUED AT 1005 PM CST TUE MAR 5 2013
THE NEW NAM...GEM AND GFS CONTINUE TO ADVERTISE INCREASING LOW
LEVEL MOISTURE WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT LEADING TO
EITHER TO THE FORMATION OF FOG OR LOW STRATUS. MEANWHILE THE RAP13
IS DRAGGING THE STRATUS ACROSS THE MISSOURI BASIN WEST TO NEAR
HIGHWAY 83 BY MORNING. IT APPEARS THE RAP IS TOO FAST. SATELLITE
TIMING TOO INDICATE IT ONLY MOVING WEST AT 5KT AND WOULD MIX OUT
DURING THE DAY AND PERHAPS RETURN WEDNESDAY NIGHT.
THE FCST FOLLOWS NAM WITH INCREASING CLOUDS AFTER MIDNIGHT AND
PATCHY FOG FORMING EAST OF HIGHWAY 61. NO DISCERNIBLE CHANGES IN
THE REST OF THE SHORT TERM FORECAST EXCEPT THE MODELS ARE SHOWING
HIGHER DEW PTS OVERNIGHT WHICH APPEARS TO BE VERIFYING.
UPDATE ISSUED AT 701 PM CST TUE MAR 5 2013
A NEW FORECAST IS OUT. RAISED OVERNIGHT LOW TEMPS A BIT IN THE
WEST WHERE A LOW LEVEL JET SHOULD KICK UP IN A FEW HOURS. LOWS
AROUND 10 TO SINGLE DIGITS EAST OF HIGHWAY 83 WHERE WINDS WILL
REMAIN CALM MOST OF THE NIGHT.
SOUTH WINDS INCREASE TO 20 TO 30 MPH WEDNESDAY AND A BLEND OF THE
NAM...GEM AND ECM INDICATED HIGHS IN THE 30S AND 40S...NO REAL
CHANGE FROM THE PREVIOUS FCST. THE NAM AND GFS SUGGEST SOME
CLOUDINESS MAY DEVELOP EAST OF HIGHWAY 83 IN THE AFTN AS RETURN
MOISTURE DEVELOPS.
EITHER FOG OR LOW CLOUDINESS DEVELOPS WEDNESDAY NIGHT WITH LOWS
IN THE 20S. SOUTH WINDS CONTINUE TO RETURN MOISTURE.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 320 PM CST TUE MAR 5 2013
TEMPERATURES THIS EVENING WILL DROP QUICKLY AS A SFC HIGH PRESSURE
MOVES ACROSS THE NORTHERN PLAINS. LIGHT WINDS...CLEAR SKIES...AND A
RELATIVELY DRY AIRMASS WILL PROVIDE FOR EFFICIENT RADIATIVE COOLING
AND LOWS IN THE LOW TO MID TEENS FOR MOST OF THE CWA. HOWEVER...AS
THE SFC HIGH SLIDES EAST OF THE AREA WINDS WILL INCREASE OUT OF THE
SOUTH FROM WEST TO EAST ACROSS THE CWA. THIS MAY ALLOW FOR WEAK
MIXING TO OCCUR LATE IN THE OVERNIGHT TOWARD EARLY TOMORROW MORNING
AND LIMIT THE PERIOD OF DIURNAL COOLING. EXPECTING OVERNIGHT LOWS TO
OCCUR EARLY BEFORE HOLDING STEADY OR EVEN WARMING A FEW DEGREES BY
DAY BREAK WEDNESDAY.
WINDS WILL CONTINUE TO INCREASE OUT OF THE SOUTH SOUTHEAST DURING
THE DAY WEDNESDAY...WITH 15 TO 25 MPH WINDS LIKELY DURING THE
AFTERNOON. CLEAR SKIES WILL CONTINUE WITH DRY AIRMASS STILL IN
PLACE. HIGH TEMPERATURES WILL BE LIMITED FOR THE EASTERN TWO-THIRDS
OF THE CWA AS 850MB TEMPS STRUGGLE TO RECOVER. EXPECTING HIGHS ONLY
IN THE 40S FOR MOST OF THE AREA...WITH 50S POSSIBLE IN THE EAST
PANHANDLE AND FAR SOUTHWEST NEBRASKA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 PM CST TUE MAR 5 2013
WEDNESDAY NIGHT THROUGH FRIDAY...MAIN FORECASTING
CHALLENGE FOR THE LATTER HALF OF THE WORK WEEK DEALS WITH
TEMPERATURES...MAINLY HIGHS ON THURSDAY AND FRIDAY AS A DEEP TROUGH
OF LOW PRESSURE ALOFT DEEPENS ACROSS THE SWRN CONUS. ON THURSDAY
WARMER AIR WILL PUSH INTO THE PANHANDLE AND WESTERN AREAS WITH SRLY
WINDS DEVELOPING IN THE AFTERNOON HOURS. FURTHER EAST
HOWEVER...LIGHT SERLY AND VARIABLE WINDS IN THE CENTRAL AND EASTERN
CWA WILL LIMIT THE WARMUP TO THE UPPER 40S/LWR 50S VS. THE UPPER 50S
TO NEAR 60 OUT WEST. ON THURSDAY NIGHT...A WEAK COOL FRONT WILL PUSH
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...STALLING ACROSS NRN KS
AND SERN NEBRASKA. SURFACE LOW PRESSURE WILL DEEPEN FRIDAY ACROSS
EASTERN COLORADO...LIFTING THE FRONT NORTH INTO SOUTH CENTRAL AND
EASTERN NEBRASKA. HOWEVER...THE FRONT IS EXPECTED TO STAY OFF TO THE
SOUTH OF THE FORECAST AREA FRIDAY...LEADING TO EASTERLY UPSLOPE
WINDS AND HIGHS IN THE 40S. EVEN HIGHS IN THE 40S...MAY BE OVERLY
OPTIMISTIC.
FRIDAY NIGHT THROUGH TUESDAY...MAIN FORECASTING CHALLENGE
CONTINUES TO BE PRECIPITATION AND PRECIPITATION TYPE IN
ASSOCIATION WITH A DEEP TROUGH OF LOW PRESSURE...WHICH TRACKS
ACROSS THE CENTRAL CONUS THIS WEEKEND. THE LATEST 12Z GFS THIS
MORNING AND THE 00Z ECMWF FROM LAST NIGHT HAVE DECENT AGREEMENT
WITH THE H5 LOW POSN SATURDAY AT 12Z. AFTER THIS
POINT...DIFFERENCES WITH THE MODEL SOLUTIONS EMERGE...IN
PARTICULAR...WHETHER THE LOW PHASES WITH THE NRN STREAM OR NOT. BY
12Z SUNDAY...THE 12Z GFS FROM THIS MORNING...PHASES THE LOW WITH
THE NRN STREAM...BECOMES POSITIVELY TILTED...AND MOVES THE SYSTEM
INTO THE MID MISSISSIPPI VALLEY BY MONDAY MORNING. THE ECMWF FROM
LAST NIGHT...IS DISCONNECTED FROM THE NRN STREAM...NEUTRAL TILTED
AND REMAINS JUST OFF TO THE SOUTH OF THE CWA THROUGH 12Z MONDAY.
THE DIFFERENCES ARE HUGE IN THE AMOUNT OF QPF GENERATED BY EACH
SOLUTION THROUGH TUESDAY. FOR EXAMPLE...FOR NORTH PLATTE ACCUM QPF
RANGES ANYWHERE FROM 0.30 WITH THE 12Z GFS SOLN...TO 2.30 INCHES
WITH THE 00Z ECMWF. THE CURRENT INHERITED FORECAST...HAS THE BEST
PRECIPITATION CHANCES FROM LATE FRIDAY NIGHT THROUGH SUNDAY
MORNING AND WILL LEAVE THIS AS IS FOR NOW GIVEN THE TIMING
UNCERTAINTIES IN THE MODELS. AS FOR PRECIPITATION TYPES...MEX AND
ECE TEMPERATURES ACROSS THE SRN AND EASTERN CWA...FAVOR ALL RAIN
AT THIS JUNCTURE...WITH A MIX AND ALL SNOW IN THE WESTERN PORTION
OF THE CWA. IF THE MORE PROGRESSIVE GFS SOLUTION VERIFIES...SNOW
AMOUNTS WILL BE MUCH LIGHTER COMPARED TO THE SLOWER 00Z EC
SOLUTION. WILL TAKE A CLOSE LOOK AT THE 12Z EC SOLUTION...AND IF
IT IS PROGRESSIVE LIKE THE 12Z GFS...SOME ELIMINATION OF POPS ON
MONDAY AND TUESDAY MAY BE IN ORDER. IN ADDITION TO ELIMINATING
POPS MONDAY AND TUESDAY...IF THE MODEL COMES IN FASTER WITH THE
SYSTEM...THE THREAT FOR LARGE ACCUMULATING SNOWS AND LONG DURATION
PRECIPITATION WILL BE MINIMIZED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1110 PM CST TUE MAR 5 2013
VFR IS EXPECTED ALL AREAS THROUGH 00Z WEDNESDAY EVENING.
THEREAFTER THE FORECAST BECOMES VERY UNCERTAIN. THE ISSUE IS RAPIDLY
INCREASING BOUNDARY LAYER MOISTURE AND THE DEVELOPMENT OF IFR CIGS
ACROSS A GOOD PORTION OF THE FCST AREA.
THE MODELS CONTINUE TO DRAG MOISTURE...CURRENTLY ACROSS THE
MISSOURI BASIN WEST TOWARD HIGHWAY 83 LATE WEDNESDAY AFTERNOON
LEADING TO THE FORMATION OF IFR WEDNESDAY NIGHT. THE RAP MODEL IS
THE FASTEST PRODUCING IFR ALONG HIGHWAY 83 BY 12Z-14Z WHILE THE
NAM...GEM AND GFS MODELS SHOW THIS FORMING AROUND 03Z WEDNESDAY
EVENING.
GIVEN THE UNCERTAINTIES OF THIS FEATURE THE BEST APPRAOCH WOULD BE
TO WAIT FOR A DEFINITIVE SATELLITE SIGNAL LATE WEDNESDAY AND THEN
MAKE THE FORECAST. SO VFR IS EXPECTED THROUGH WEDNESDAY AFTERNOON
AND PRESUMABLY...SOME SIGNAL SHOULD DEVELOP AROUND 03Z-06Z WEDNESDAY
EVENING.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...MARTIN
LONG TERM...CLB
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1014 PM CST TUE MAR 5 2013
.SYNOPSIS...
ISSUED AT 320 PM CST TUE MAR 5 2013
H5 HAND ANALYSIS THIS MORNING...INDICATES A CONTINUED ACTIVE PATTERN
ACROSS NOAM. A STRONG SHORTWAVE WAS LOCATED ACROSS NWRN MISSOURI
WITH DECENT HT FALLS NOTED FROM THE TWIN CITIES SWD INTO SWRN MO.
FURTHER WEST...A LOW AMPLITUDE RIDGE EXTENDED FROM SO CALIFORNIA NWD
TO THE IDAHO PANHANDLE. WHILE WEST OF THIS FEATURE...A TROUGH
EXTENDED FROM ERN BRITISH COLUMBIA...SWD TO A CLOSED LOW OFF THE
COAST OF OREGON. ACROSS THE EASTERN CONUS...A CLOSED LOW WAS PRESENT
OVER THE CANADIAN MARITIMES WITH HIGH PRESSURE NOTED OVER NRN
QUEBEC. AT THE SURFACE...HIGH PRESSURE HAS BUILT INTO WESTERN
NEBRASKA THIS AFTERNOON RESULTING IN LIGHT WINDS. FURTHER
EAST...BREEZY CONDITIONS CONTINUED. TEMPERATURES AS OF 3 PM CST
RANGED FROM 32 AT O`NEILL TO 41 AT OGALLALA.
&&
.UPDATE...
ISSUED AT 1005 PM CST TUE MAR 5 2013
THE NEW NAM...GEM AND GFS CONTINUE TO ADVERTISE INCREASING LOW
LEVEL MOISTURE WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT LEADING TO
EITHER TO THE FORMATION OF FOG OR LOW STRATUS. MEANWHILE THE RAP13
IS DRAGGING THE STRATUS ACROSS THE MISSOURI BASIN WEST TO NEAR
HIGHWAY 83 BY MORNING. IT APPEARS THE RAP IS TOO FAST. SATELLITE
TIMING TOO INDICATE IT ONLY MOVING WEST AT 5KT AND WOULD MIX OUT
DURING THE DAY AND PERHAPS RETURN WEDNESDAY NIGHT.
THE FCST FOLLOWS NAM WITH INCREASING CLOUDS AFTER MIDNIGHT AND
PATCHY FOG FORMING EAST OF HIGHWAY 61. NO DISCERNIBLE CHANGES IN
THE REST OF THE SHORT TERM FORECAST EXCEPT THE MODELS ARE SHOWING
HIGHER DEW PTS OVERNIGHT WHICH APPEARS TO BE VERIFYING.
UPDATE ISSUED AT 701 PM CST TUE MAR 5 2013
A NEW FORECAST IS OUT. RAISED OVERNIGHT LOW TEMPS A BIT IN THE
WEST WHERE A LOW LEVEL JET SHOULD KICK UP IN A FEW HOURS. LOWS
AROUND 10 TO SINGLE DIGITS EAST OF HIGHWAY 83 WHERE WINDS WILL
REMAIN CALM MOST OF THE NIGHT.
SOUTH WINDS INCREASE TO 20 TO 30 MPH WEDNESDAY AND A BLEND OF THE
NAM...GEM AND ECM INDICATED HIGHS IN THE 30S AND 40S...NO REAL
CHANGE FROM THE PREVIOUS FCST. THE NAM AND GFS SUGGEST SOME
CLOUDINESS MAY DEVELOP EAST OF HIGHWAY 83 IN THE AFTN AS RETURN
MOISTURE DEVELOPS.
EITHER FOG OR LOW CLOUDINESS DEVELOPS WEDNESDAY NIGHT WITH LOWS
IN THE 20S. SOUTH WINDS CONTINUE TO RETURN MOISTURE.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 320 PM CST TUE MAR 5 2013
TEMPERATURES THIS EVENING WILL DROP QUICKLY AS A SFC HIGH PRESSURE
MOVES ACROSS THE NORTHERN PLAINS. LIGHT WINDS...CLEAR SKIES...AND A
RELATIVELY DRY AIRMASS WILL PROVIDE FOR EFFICIENT RADIATIVE COOLING
AND LOWS IN THE LOW TO MID TEENS FOR MOST OF THE CWA. HOWEVER...AS
THE SFC HIGH SLIDES EAST OF THE AREA WINDS WILL INCREASE OUT OF THE
SOUTH FROM WEST TO EAST ACROSS THE CWA. THIS MAY ALLOW FOR WEAK
MIXING TO OCCUR LATE IN THE OVERNIGHT TOWARD EARLY TOMORROW MORNING
AND LIMIT THE PERIOD OF DIURNAL COOLING. EXPECTING OVERNIGHT LOWS TO
OCCUR EARLY BEFORE HOLDING STEADY OR EVEN WARMING A FEW DEGREES BY
DAY BREAK WEDNESDAY.
WINDS WILL CONTINUE TO INCREASE OUT OF THE SOUTH SOUTHEAST DURING
THE DAY WEDNESDAY...WITH 15 TO 25 MPH WINDS LIKELY DURING THE
AFTERNOON. CLEAR SKIES WILL CONTINUE WITH DRY AIRMASS STILL IN
PLACE. HIGH TEMPERATURES WILL BE LIMITED FOR THE EASTERN TWO-THIRDS
OF THE CWA AS 850MB TEMPS STRUGGLE TO RECOVER. EXPECTING HIGHS ONLY
IN THE 40S FOR MOST OF THE AREA...WITH 50S POSSIBLE IN THE EAST
PANHANDLE AND FAR SOUTHWEST NEBRASKA.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 PM CST TUE MAR 5 2013
WEDNESDAY NIGHT THROUGH FRIDAY...MAIN FORECASTING
CHALLENGE FOR THE LATTER HALF OF THE WORK WEEK DEALS WITH
TEMPERATURES...MAINLY HIGHS ON THURSDAY AND FRIDAY AS A DEEP TROUGH
OF LOW PRESSURE ALOFT DEEPENS ACROSS THE SWRN CONUS. ON THURSDAY
WARMER AIR WILL PUSH INTO THE PANHANDLE AND WESTERN AREAS WITH SRLY
WINDS DEVELOPING IN THE AFTERNOON HOURS. FURTHER EAST
HOWEVER...LIGHT SERLY AND VARIABLE WINDS IN THE CENTRAL AND EASTERN
CWA WILL LIMIT THE WARMUP TO THE UPPER 40S/LWR 50S VS. THE UPPER 50S
TO NEAR 60 OUT WEST. ON THURSDAY NIGHT...A WEAK COOL FRONT WILL PUSH
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...STALLING ACROSS NRN KS
AND SERN NEBRASKA. SURFACE LOW PRESSURE WILL DEEPEN FRIDAY ACROSS
EASTERN COLORADO...LIFTING THE FRONT NORTH INTO SOUTH CENTRAL AND
EASTERN NEBRASKA. HOWEVER...THE FRONT IS EXPECTED TO STAY OFF TO THE
SOUTH OF THE FORECAST AREA FRIDAY...LEADING TO EASTERLY UPSLOPE
WINDS AND HIGHS IN THE 40S. EVEN HIGHS IN THE 40S...MAY BE OVERLY
OPTIMISTIC.
FRIDAY NIGHT THROUGH TUESDAY...MAIN FORECASTING CHALLENGE
CONTINUES TO BE PRECIPITATION AND PRECIPITATION TYPE IN
ASSOCIATION WITH A DEEP TROUGH OF LOW PRESSURE...WHICH TRACKS
ACROSS THE CENTRAL CONUS THIS WEEKEND. THE LATEST 12Z GFS THIS
MORNING AND THE 00Z ECMWF FROM LAST NIGHT HAVE DECENT AGREEMENT
WITH THE H5 LOW POSN SATURDAY AT 12Z. AFTER THIS
POINT...DIFFERENCES WITH THE MODEL SOLUTIONS EMERGE...IN
PARTICULAR...WHETHER THE LOW PHASES WITH THE NRN STREAM OR NOT. BY
12Z SUNDAY...THE 12Z GFS FROM THIS MORNING...PHASES THE LOW WITH
THE NRN STREAM...BECOMES POSITIVELY TILTED...AND MOVES THE SYSTEM
INTO THE MID MISSISSIPPI VALLEY BY MONDAY MORNING. THE ECMWF FROM
LAST NIGHT...IS DISCONNECTED FROM THE NRN STREAM...NEUTRAL TILTED
AND REMAINS JUST OFF TO THE SOUTH OF THE CWA THROUGH 12Z MONDAY.
THE DIFFERENCES ARE HUGE IN THE AMOUNT OF QPF GENERATED BY EACH
SOLUTION THROUGH TUESDAY. FOR EXAMPLE...FOR NORTH PLATTE ACCUM QPF
RANGES ANYWHERE FROM 0.30 WITH THE 12Z GFS SOLN...TO 2.30 INCHES
WITH THE 00Z ECMWF. THE CURRENT INHERITED FORECAST...HAS THE BEST
PRECIPITATION CHANCES FROM LATE FRIDAY NIGHT THROUGH SUNDAY
MORNING AND WILL LEAVE THIS AS IS FOR NOW GIVEN THE TIMING
UNCERTAINTIES IN THE MODELS. AS FOR PRECIPITATION TYPES...MEX AND
ECE TEMPERATURES ACROSS THE SRN AND EASTERN CWA...FAVOR ALL RAIN
AT THIS JUNCTURE...WITH A MIX AND ALL SNOW IN THE WESTERN PORTION
OF THE CWA. IF THE MORE PROGRESSIVE GFS SOLUTION VERIFIES...SNOW
AMOUNTS WILL BE MUCH LIGHTER COMPARED TO THE SLOWER 00Z EC
SOLUTION. WILL TAKE A CLOSE LOOK AT THE 12Z EC SOLUTION...AND IF
IT IS PROGRESSIVE LIKE THE 12Z GFS...SOME ELIMINATION OF POPS ON
MONDAY AND TUESDAY MAY BE IN ORDER. IN ADDITION TO ELIMINATING
POPS MONDAY AND TUESDAY...IF THE MODEL COMES IN FASTER WITH THE
SYSTEM...THE THREAT FOR LARGE ACCUMULATING SNOWS AND LONG DURATION
PRECIPITATION WILL BE MINIMIZED.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 524 PM CST TUE MAR 5 2013
VFR IS EXPECTED ALL AREAS TONIGHT THROUGH 21Z WEDNESDAY.
THEREAFTER...THERE ARE INDICATIONS IN THE MODELS THAT THE CLOUD
DECK ACROSS THE MISSOURI BASIN WILL GET SWEPT WESTWARD AFFECTING
AREAS EAST OF HIGHWAY 83. FLIGHT CONDITIONS COULD STILL REMAIN VFR
AS CIGS WOULD OPERATE AT BKN035 BUT LOWER CIGS MIGHT DEVELOP.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...MARTIN
LONG TERM...CLB
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
355 AM EST WED MAR 6 2013
.SYNOPSIS...
A SNOWSTORM WILL SLIDE SOUTHEAST ACROSS THE VIRGINIAS TODAY...WHILE
JUST BRINGING SOME CLOUDS TO OUR AREA. AN UPPER LEVEL DISTURBANCE
WILL THEN BRING A CHANCE FOR SOME LIGHT RAIN AND SNOW SHOWERS
THURSDAY...WITH SOME STEADIER SNOW THEN EXPECTED FOR AREAS ALONG AND
EAST OF THE GENESEE VALLEY THURSDAY NIGHT INTO EARLY FRIDAY. AFTER
THAT...A RETURN TO DRY WEATHER AND INCREASING WARMTH WILL FOLLOW FOR
THE WEEKEND WITH TEMPERATURES RISING ABOVE NORMAL.
&&
.NEAR TERM /THROUGH TONIGHT/...
IN THIS PERIOD...A COMPLEX WINTER STORM DRAPED FROM SOUTHERN OHIO TO
NORTH CAROLINA WILL CONSOLIDATE INTO A SINGLE LOW ALONG THE VIRGINIA
COASTLINE TODAY...BEFORE SLOWLY DRIFTING OFFSHORE TONIGHT IN
RESPONSE TO A STRONG SHORTWAVE TROUGH DROPPING SOUTHEAST INTO THE
GREAT LAKES. ON SUCH A TRACK...THIS SYSTEM/S SHIELD OF STEADY
PRECIPITATION WILL REMAIN TO OUR SOUTH...WHILE OUR AREA REMAINS
MAINLY DRY WITH JUST A GENERAL INCREASE IN CLOUD COVER EXPECTED
OVER TIME. THE BEST CHANCES FOR ANY PRECIP MAY ACTUALLY COME LATER
TONIGHT AS THE AFOREMENTIONED SHORTWAVE TROUGH APPROACHES FROM THE
NORTHWEST...HOWEVER THE MOISTURE AND LIFT ASSOCIATED WITH THIS LOOKS
WEAK ENOUGH TO KEEP POPS CONFINED TO THE SLIGHT CHANCE RANGE AND
BELOW.
WITH REGARD TO TEMPS...925 MB TEMPS SHOULD RECOVER BACK INTO THE -1C
TO -3C RANGE TODAY AS WARMER AIR GETS DRAWN WESTWARD AROUND THE
NORTH SIDE OF STORM SYSTEM. EVEN WITH AN INCREASE IN CLOUD COVER
EXPECTED AND WINDS TURNING MORE NORTHEASTERLY OVER TIME...THIS
SHOULD STILL BE ENOUGH FOR HIGHS TO REACH INTO THE MID TO UPPER 30S
TODAY...WITH SOME SPOTS IN THE FINGER LAKES LIKELY REACHING 40
DEGREES. UNDER INCREASED AMOUNTS OF CLOUD COVER...LOWS TONIGHT WILL
THEN RANGE FROM THE LOWER 20S ACROSS INTERIOR PORTIONS OF THE
SOUTHERN TIER AND NORTH COUNTRY...TO THE UPPER 20S ACROSS THE LAKE
PLAINS SOUTH OF LAKE ONTARIO.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
UNSETTLED WEATHER WILL RETURN TO WESTERN AND NORTH CENTRAL NEW YORK
ON THURSDAY AS AN UPPER LEVEL LOW WILL DIVE SOUTHEAST ACROSS THE
AREA FROM THE UPPER GREAT LAKES. LOOK FOR SCATTERED RAIN AND SNOW
SHOWERS TO DEVELOP DURING THE DAY ON THURSDAY AND CHANGE OVER TO
MAINLY SNOW SHOWERS DURING THE AFTERNOON AND EVENING AS THE COLD
CORE OF THE LOW MOVES OVERHEAD. ACTIVITY ACROSS WESTERN NEW YORK
SHOULD BE SCATTERED ENOUGH GIVEN THE POSITION DIRECTLY UNDERNEATH
THE PASSING LOW AND TEMPERATURES SHOULD BE WARM ENOUGH THAT ANY SNOW
ACCUMULATIONS SHOULD BE NEGLIGIBLE...ON THE ORDER OF A TENTH OR TWO
ACROSS HIGHER ELEVATIONS OF THE SOUTHERN TIER WITH LITTLE IF ANY
ACCUMULATIONS ELSEWHERE.
EAST OF THE GENESEE VALLEY AND ACROSS THE NORTH COUNTRY THERE IS A
POTENTIAL FOR MORE SIGNIFICANT SNOW ACCUMULATIONS. AS THE SHORTWAVE
DIVES ACROSS WESTERN NEW YORK...THERE IS A POSSIBILITY THAT IT MAY
INTERACT WITH AN INVERTED SURFACE TROUGH PROGGED TO EXTEND ACROSS
THE HUDSON VALLEY AND UPSTATE NEW YORK FROM THE STORM SYSTEM
CURRENTLY IMPACTING THE MID-ATLANTIC STATES TO PRODUCE SIGNIFICANT
ACCUMULATIONS OF SNOW ACROSS PORTIONS OF UPSTATE NEW YORK INCLUDING
THE COUNTIES EAST AND SOUTHEAST OF LAKE ONTARIO. HOWEVER AT THIS
POINT THERE IS STILL A FAIR AMOUNT OF UNCERTAINTY AS TO HOW FAR
NORTH/WEST THIS POTENTIAL BAND OF SNOW WILL DEVELOP AS THIS
DEVELOPMENT WILL HINGE ON THE SPEED OF THE UPPER LEVEL TROUGH AND
EXACTLY HOW FAR INLAND THE DEEPEST MOISTURE AND WARM ADVECTION WILL
PENETRATE...WHICH IS ITSELF A FUNCTION OF THE EXACT TRACK OF THE
DEVELOPING STORM SYSTEM AS IT DEPARTS THE EAST COAST. GIVEN ALL OF
THE COMPLEX ISSUES...WILL HOLD OFF ON ANY WATCHES AT THIS POINT AND
LOOK FOR GREATER CLARITY IN FUTURE MODEL RUNS.
A ROBUST RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE LOWER GREAT
LAKES ON FRIDAY IN THE WAKE OF THE DEPARTING LOW BRINGING A RETURN
TO DRY WEATHER. NORTHERLY FLOW AHEAD OF THE HIGH WILL LIKELY KEEP A
DECENT AMOUNT OF CLOUD COVER IN PLACE ACROSS THE AREA FOR MUCH OF
THE DAY AND THIS MAY HOLD TEMPERATURES IN THE MID TO UPPER 30S...HOWEVER
CLOUDS SHOULD GRADUALLY THIN OUT AS DRIER AIR WORKS ITS WAY ACROSS
THE REGION LATER FRIDAY AFTERNOON AND EVENING. THE CLEARING SKIES
AND DIMINISHING WINDS AS THE SURFACE HIGH MOVES OVERHEAD FRIDAY
NIGHT WILL ALLOW TEMPERATURES TO DROP INTO THE 20S EVEN AS
TEMPERATURES ALOFT RISE ABOVE NORMAL.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE RIDGE WILL SLIDE OFF TO THE EAST EARLY IN THE PERIOD AS BOTH
THE GFS AND ECMWF SHOW A WEAK FRONTAL BOUNDARY CROSSING THE LOWER
LAKES LATE IN THE WEEKEND. TIMING OF THE FRONTAL BOUNDARY IS
HANDLED DIFFERENT BY THE TWO MODELS...AS THE MODELS HAVING
DIFFICULTY HANDLING THE SHORT WAVE ENERGY COMING OUT OF THE PLAINS
AND DAMPENING THE UPPER RIDGE. IT DOES APPEAR THAT MOISTURE WILL
BE LIMITED ENOUGH TO KEEP PRECIPITATION IN THE BROADBRUSH LOW
CHANCE CATEGORY...BUT THAT IS AS MUCH DETAIL AS CAN BE AFFORDED AT
THIS POINT. USED A CONSENSUS OF GUIDANCE FOR THIS PERIOD GIVEN THE
LIMITED CONFIDENCE IN ANY ONE MODEL.
EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE DEVELOPS EARLY NEXT WEEK
AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE PHASING OF THE
NORTHERN AND SOUTHERN STREAMS OVER THE CONUS. CONTINUED TO USE A
CONSENSUS OF GUIDANCE...BUT OVERALL CONFIDENCE IN THIS PORTION OF
THE FORECAST IS BELOW AVERAGE.
THE OVERALL TEMPERATURE PATTERN SHOULD FEATURE A GENERAL WARMER THAN
NORMAL REGIME.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
AS OF 08Z...SKIES REMAIN MAINLY CLEAR NORTH OF THE SOUTHERN
TIER...WHILE SOME THICKER CIRRUS AND PATCHY STRATUS PERSIST FROM
KJHW OVER TO KELZ. THROUGH SUNRISE...EXPECT A SUBSIDENCE INVERSION
TO CONTINUE TO LOWER AND SHARPEN AND LIKELY LEAD TO SOME EXPANSION
OF THE LOWER CLOUDS...HOWEVER THESE WILL REMAIN PATCHY IN COVERAGE
AND MVFR IN NATURE GIVEN ONLY MARGINAL MOISTURE...WITH CONFIDENCE IN
TIMING/LOCATION REMAINING LOW. BASED ON THE LATEST RAP AND THE 18Z
NAM...WILL CARRY A PERIOD OF LLWS AT JHW.
THROUGH THE REMAINDER OF TODAY AND TONIGHT...LOW PRESSURE WILL
REMAIN WELL SOUTH AND EAST OF THE AREA. OVER TIME...INITIAL VFR/
PATCHY MVFR CONDITIONS THIS MORNING WILL GRADUALLY LOWER TO MVFR AS
MOISTURE INCREASES IN THE LOWER LEVELS OF THE ATMOSPHERE...WITH SOME
IFR CIGS BECOMING POSSIBLE ACROSS THE SOUTHERN TIER TONIGHT.
OUTLOOK...
THURSDAY...MVFR WITH A CHANCE OF RAIN AND SNOW SHOWERS.
THURSDAY NIGHT...MVFR/IFR WITH LIGHT SNOW LIKELY FROM THE GENESEE
VALLEY EASTWARD...OTHERWISE MVFR WITH A CHANCE OF SNOW SHOWERS
FURTHER WEST.
FRIDAY...MVFR WITH A CHANCE OF SNOW SHOWERS IN THE MORNING...THEN
BECOMING MAINLY VFR.
SATURDAY AND SUNDAY...VFR.
&&
.MARINE...
COMPLEX LOW PRESSURE DRAPED FROM SOUTHERN OHIO TO NORTH CAROLINA
WILL CONSOLIDATE INTO A SINGLE LOW ALONG THE VIRGINIA COASTLINE
TODAY...BEFORE SLOWLY DRIFTING OUT TO SEA TONIGHT AND THURSDAY. AS
THIS SYSTEM PUSHES EASTWARD...THE BRISK EASTERLY FLOW CURRENTLY
FOUND ACROSS THE LOWER LAKES WILL TURN MORE NORTHEASTERLY TODAY...
THEN WILL GRADUALLY WEAKEN TONIGHT AND THURSDAY WHILE ALSO TENDING
MORE NORTHERLY. THIS WILL EVENTUALLY LEAD TO WINDS AND WAVES FALLING
BELOW ADVISORY CRITERIA OVER TIME...HOWEVER UNTIL THIS HAPPENS SMALL
CRAFT ADVISORIES WILL REMAIN IN EFFECT AS OUTLINED BELOW.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LEZ040.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
LOZ043.
SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 10 PM EST
THIS EVENING FOR LOZ044.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
LOZ042.
&&
$$
SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...WOOD
LONG TERM...TMA
AVIATION...APFFEL/JJR
MARINE...JJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1239 AM EST WED MAR 6 2013
.SYNOPSIS...
A POTENT STORM SYSTEM WILL CROSS THE AREA TONIGHT...BRINGING SHOWERS
AND PERHAPS A RUMBLE OF THUNDER. COLDER AIR RETURNS ALONG WITH
STRONG GUSTY WINDS WEDNESDAY INTO THURSDAY AS THIS STORM SYSTEM
LIFTS OFF TO THE NORTHEAST. THE LATE WEEK PERIOD WILL FEATURE A
RETURN OF SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 12:30 AM WEDNESDAY...SHOWERS HAVE ENDED FOR THE NIGHT AS
RAIN-SHIELD MOVES OFFSHORE. HAVE UPDATED FORECAST ACCORDINGLY.
COLD FRONT WILL BE MOVING OFFSHORE SHORTLY. NO OTHER CHANGES TO
THE FORECAST WITH THE LATEST UPDATE. WIND ADVISORY REMAINS IN
EFFECT. PREVIOUS DISCUSSION FOLLOWS:
A POWERFUL UPPER LEVEL LOW IS STILL STRENGTHENING AS IT MOVES EAST
ACROSS SOUTHERN KENTUCKY THIS EVENING AND TOWARD NORTHERN NORTH
CAROLINA WEDNESDAY MORNING. SURFACE LOW PRESSURE CENTERED OVER
SOUTHERN OHIO IS OCCLUDING AS A NEW CENTER DEVELOPING OVER THE NC
WESTERN PIEDMONT BECOMES THE DOMINANT LOW. A COLD FRONT SOUTH OF
THIS DEVELOPING LOW EXTENDS FROM NEAR MONROE NC SOUTH THROUGH
COLUMBIA AND INTO EASTERN GEORGIA.
SHOWERS AND EMBEDDED THUNDERSTORMS HAVE ACCOMPANIED THE COLD FRONT
ACROSS GEORGIA AND INTO THE CAROLINAS THIS EVENING. THERMODYNAMIC
CONDITIONS WERE MUCH MORE FAVORABLE FOR UPRIGHT CONVECTION ACROSS
GEORGIA AND THE WESTERN HALF OF SOUTH CAROLINA EARLIER. AS THE LINE
HAS MOVED INTO THE EASTERN CAROLINAS SURFACE CAPE IS ZERO...WHILE
PARCELS LIFTED FROM 875 MB CONTAIN MEAGER INSTABILITY ESTIMATED BY
THE LATEST RUC AT 100 J/KG OR LESS. BULK SHEAR THROUGH THE 0-6 KM
LAYER IS EXTREME (60-70 KT) WHICH IS PROBABLY TOO MUCH GIVEN THE
MEAGER INSTABILITY...RESULTING IN ANY UPDRAFTS GETTING DILUTED BY
THE ENVIRONMENT. WHILE I AM MAINTAINING HIGH POPS FOR MEASURABLE
PRECIP THIS EVENING...ACTUAL GAUGE-MEASURED RAINFALL AMOUNTS SHOULD
REMAIN QUITE LOW: 0.05 TO 0.15 INCHES FOR MOST AREAS.
AFTER THE FRONT SWEEPS OFFSHORE SHORTLY AFTER MIDNIGHT MUCH COLDER
AIR WILL SURGE INTO THE AREA. THE CHANGE IN AIRMASS IS VERY SUDDEN:
850 MB TEMPS SHOULD FALL FROM +7C AT 00Z TO -5C AT 12Z...
ACCOMPANIED BY SIMILAR EXTREME CHANGES IN LAYER THICKNESS VALUES AND
MID-LEVEL HEIGHTS. AS THE UPPER LOW MAKES ITS CLOSEST APPROACH TO
THE AREA WEDNESDAY AFTERNOON THE TROPOPAUSE SHOULD ACTUALLY LOWER
TO JUST ABOVE 500 MB OR ABOUT 19000 FT AGL. THIS IS WELL BELOW
TYPICAL VALUES AND SHOWS JUST HOW POWERFUL THIS SYSTEM IS. FORECAST
SOUNDINGS FROM THE RUC...NAM AND GFS SHOW DRY ADIABATIC LAPSE RATES
DEVELOPING THROUGH THE LOWEST SEVERAL THOUSAND FEET OF THE
ATMOSPHERE BY 09Z (4 AM WEDNESDAY) AS COLD ADVECTION STRENGTHENS.
WIND SPEEDS JUST 1000 FT AGL SHOULD INCREASE TO 30 KNOTS...AND TO
NEARLY 40 KNOTS AT 2000 FT AGL. THIS MOMENTUM WILL WORK ITS WAY DOWN
IN GUSTS LATE TONIGHT AND ESPECIALLY WEDNESDAY AFTER THE SUN RISES
AND LAPSE RATES ARE FORCED TO BECOME DRY ADIABATIC OVER AN EVEN
DEEPER LAYER. THE WIND ADVISORY RAISED EARLIER TODAY APPEARS TO BE
AN EXCELLENT CALL!
LOW TEMPERATURES TONIGHT SHOULD FALL TO AROUND 40 INLAND WITH MID
40S AT THE COAST...ALL WITH A DEEPLY MIXED ATMOSPHERE PREVENTING ANY
HINT OF A RADIATIONAL INVERSION.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...STRONG LOW PRESSURE SYSTEM OVER THE MID
ATLANTIC COAST EARLY WED MORNING WILL BE MOVE SLOWLY OFF THE COAST
THROUGH THE PERIOD AS STRONG HIGH PRESSURE BUILDS IN BEHIND IT. A
VERY TIGHT GRADIENT WILL EXIST BETWEEN THE TWO SYSTEMS THROUGH WED
INTO THURS WITH DEEP LAYER W-NW WINDS ADVECTING IN VERY DRY AND
COOL AIR ON BACK END OF LOW. EXPECT STRONG AND GUSTY WESTERLY
WINDS INITIALLY ON WED BECOMING NORTHWEST ON THURS. WINDS WILL BE
STRONGEST OVER COASTAL NORTH CAROLINA WHERE WINDS WILL RUN BETWEEN
20 TO 30 MPH WITH GUSTS UP TO 45 MPH. WILL ISSUE WIND ADVISORY FOR
WEDNESDAY.
COLD AND DRY ADVECTION WILL CONTINUE THROUGH WED INTO THURS ON THE
BACK END OF THE LOW. PCP WATER VALUES DROP DOWN TO LESS THAN A
QUARTER OF AN INCH AS DRY SLOT WRAPPING AROUND LOW MOVES INTO
AREA. A POTENT VORT MAX ROTATES AROUND THE LOW THROUGH WED AFTN
INTO EARLY EVENING OVER THE CAROLINAS. THIS WILL PRODUCE THE
POTENTIAL FOR CLOUDS BUT FOR NOW WILL KEEP PCP OUT OF FORECAST
WITH WESTERLY DOWNSLOPE FLOW THROUGH WED AFTN. POTENTIAL INCREASES
THROUGH WED AFTERNOON. MODELS SHOW PCP WATER VALUES REACHING UP TO
A HALF INCH REACHING INTO NORTHERN TIER COUNTIES OF CWA...BUT FOR
THE MOST PART THE BEST CHC OF ANY PCP WILL BE NORTH OF AREA.
TEMPS WILL BE SOMEWHAT CHALLENGING AS OVERNIGHT LOWS HEADING INTO
WED WILL BE ON THE WARM SIDE...UP AROUND 50 AT DAYBREAK. BUT THEN
PLENTY OF COOL AIR WILL RUSH IN FIRST FEW HOURS OF DAYBREAK.
EXPECT HIGHEST TEMP FOR WED TO OCCUR JUST AROUND MIDNIGHT AND
AFTERNOON TEMPS TO BE CLOSER TO 50. 850 TEMPS BOTTOM OUT RIGHT
AROUND NOON ON WED WITH -5C. TEMPS WILL DROP INTO THE 30S IN CAA
THROUGH WED NIGHT AND THEREFORE EXPECT TEMPS ON THE COOL SIDE
AGAIN FOR THURS. WILL UNDERCUT GUIDANCE AND KEEP WITH LOWER 50S
MOST PLACES ON THURS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...QUIET WEATHER FOR MUCH OF THE EXTENDED WITH
TEMPS WARMING TO...POTENTIALLY...WELL ABOVE NORMAL EARLY NEXT WEEK.
A COLD FRONT WILL APPROACH AT THE END OF THE PERIOD...BRINGING THE
ONLY CHANCE FOR PRECIP.
LARGE LOW PRESSURE OFF THE NEW ENGLAND COAST AND A RIDGE OF HIGH
PRESSURE BUILDING DOWN FROM THE NW WILL KEEP COOL NORTHERLY FLOW
ACROSS THE CAROLINAS FRIDAY. THE LOW PRESSURE WILL PUSH OFF TO THE
EAST BY SATURDAY AS HIGH PRESSURE RIDGES DOWN TO THE GULF COAST
THROUGH THE WKND...BECOMING CENTERED OVERHEAD SUNDAY. ALTHOUGH THIS
KEEPS LIGHT NORTH WINDS AND WEAK CAA...TEMPS WILL GRADUALLY WARM
FROM MID/UPPER 50S FRIDAY...INTO THE MID 60S SUNDAY THANKS TO THE
LIGHTER WINDS AND FULL MARCH INSOLATION. AS HIGH PUSHES OFFSHORE
MON/TUE...RETURN FLOW PUMPS MUCH WARMER AIR INTO THE REGION WITH
TEMPS RISING TO WELL ABOVE NORMAL...APPROACHING 70 BOTH
DAYS...ALTHOUGH HIGH LEVEL CLOUD COVER WILL BE ON THE INCREASE NEXT
WEEK. MINS THROUGH THE PERIOD WILL GRADUALLY INCREASE AS WELL...FROM
MID 30S FRIDAY NIGHT...TO UPPER 40S MON NIGHT.
GUIDANCE SUGGESTS A COLD FRONT WILL CROSS EARLY TUESDAY...BUT EXPECT
THIS TO BE SLOWED BY THE ANTECEDENT RIDGING AND INCREASINGLY
BOUNDARY-PARALLEL MID LEVEL FLOW. DECENT THETA-E RIDGING AHEAD OF
THIS FEATURE WILL SUPPORT SHOWERS TUESDAY...BUT BEING D7 AND
EXPECTED SLOWING OF BOUNDARY WILL CARRY ONLY SCHC/SILENT FOR NOW ON
TUE.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 06Z...FRONT PROBABLY THROUGH FLO AND LBT AND WILL PUSH
OFFSHORE SHORTLY AFTER TAF ISSUANCE. WINDS WILL SHIFT WESTERLY
WITH MODERATE TO STRONG COLD AIR ADVECTION COMMENCING TOWARD
MORNING. STRONG MIXING AND GRADIENT WILL KICK WINDS WELL INTO THE
30 KT RANGE BY MIDDAY. MOISTURE ROTATION AROUND THE STRONG LOW
NORTH OF HERE...ALONG WITH COLD AIR ALOFT...WILL CREATE A STRATA
CU CEILING MAINLY NORTH OF THE REGION...BUT LBT AND ILM MAY GET
INTO THE ACT. LOOK FOR WINDS TO DIMINISH AFTER SUNSET...SETTLING
DOWN THE MOST AT THE SOUTHERN TERMINALS WHERE THE GRADIENT IS
RELATIVELY WEAKER.
EXTENDED OUTLOOK...VFR CONDITIONS SHOULD PREVAIL THROUGH SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM WEDNESDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO
THE MARINE FORECAST THIS EVENING. GALE WARNING REMAINS IN EFFECT
FOR DANGEROUSLY STRONG WINDS AND HIGH SEAS ASSOCIATED WITH A
STRONG FRONTAL SYSTEM THAT WILL SOON MOVE OFFSHORE. PREVIOUS
DISCUSSION FOLLOWS:
SOUTHWEST WINDS ARE STEADILY INCREASING AHEAD OF A STRONG COLD FRONT
NOW PUSHING INTO THE WESTERN CAROLINAS. THIS FRONT WILL RAPIDLY MOVE
EAST AND ACROSS THE COASTAL WATERS AFTER MIDNIGHT...ACCOMPANIED BY A
LINE OF SHOWERS AND ISOLATED THUNDERSTORMS. BEHIND THE FRONT SURFACE
PRESSURES WILL RISE RAPIDLY WHICH SHOULD RESULT IN THE ONSET OF
GALE-FORCE WINDS...AT LEAST IN GUSTS...SEVERAL HOURS BEFORE SUNRISE.
MODELS ARE IN EXCELLENT AGREEMENT WITH THE TIMING AND ANTICIPATED
HIGH IMPACT OF THIS SYSTEM TO MARINERS. NO SIGNIFICANT CHANGES HAVE
BEEN MADE TO THE FORECAST WITH THIS EARLY EVENING UPDATE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...POTENT LOW PRESSURE SYSTEM WILL BE MOVING
SLOWLY OFF THE MID ATLANTIC COAST THROUGH PERIOD. A VERY TIGHT
GRADIENT WILL EXIST BETWEEN THIS LOW AND STRONG HIGH PRESSURE
BUILDING IN ON THE BACK END. TIGHTENED GRADIENT FLOW COMBINED WITH
COLD SURGE ON BACK END OF LOW WILL PRODUCE STRONG GUSTY WESTERLY
WINDS UP TO 35 KTS WITH HIGHER GUSTS THROUGH WED. A GALE WARNING WILL
REMAIN IN EFFECT INTO WED EVENING.
MAX SEAS WILL BE WED MORNING UP AROUND 7 TO 10 FT WITH HIGHER SEAS
JUST OUTSIDE OF LOCAL WATERS. THE OFF SHORE FLOW WILL ALLOW NEAR
SHORE SEAS TO SUBSIDE BY THE END OF WED BUT STILL EXPECT 6 TO 8 FT
SEAS THROUGH WED EVENING. EXPECT A SLOW DECREASE IN SPEEDS HEADING
INTO THURSDAY AS THE LOW PRESSURE SYSTEM MOVES FURTHER OFF THE
MID ATLANTIC COAST. SEAS WILL CONTINUE TO SUBSIDE IN SLOWLY
WEAKENING OFF SHORE FLOW. EXPECT SEAS DOWN BELOW SCA BY DAYBREAK
THURSDAY WITH HEIGHTS AROUND 4 TO 5 FT IN OUTER WATERS AND LESS
THAN 3 FT NEAR SHORE. BY THURSDAY EVENING EXPECT SEAS 2-4 FEET
ACROSS THE WATERS.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...VERY LARGE LOW PRESSURE MOVING SLOWLY OFF THE
NEW ENGLAND COAST WILL KEEP A PINCHED GRADIENT WITH WINDS VEERING
FROM NW TO NORTH THROUGH FRIDAY. WINDS WILL BE 15-20 KTS...WITH
GUSTS UP TO 30 KTS DURING THE DAY. ALTHOUGH THIS IS PRIMARILY AN
OFFSHORE DIRECTION...SEAS WILL REMAIN ELEVATED AT 2-5 FT.
HOWEVER...AS WINDS BECOME SLIGHTLY MORE NORTHERLY LATE FRIDAY...WAVE
HEIGHTS NEAR THE 20NM BOUNDARY OF AMZ250 AND AMZ252 MAY APPROACH
6FT...AND A SHORT SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY NIGHT
THROUGH SATURDAY MORNING. SEAS THROUGH SATURDAY WILL BE FORMED VIA A
COMBINATION OF NORTHERLY WIND WAVES...AND AN EASTERLY BACK SWELL OF
2-4 FT AT 13 SEC.
HIGH PRESSURE BUILDS DOWN ACROSS THE AREA FROM THE NW SAT/SUN
CAUSING WINDS TO SHIFT SLOWLY FROM NORTH TO SE BY LATE SUNDAY...WITH
SPEEDS DECREASING TO LESS THAN 10 KTS DUE TO THE RELAXED GRADIENT.
SEAS RESPOND ONLY SLOWLY WITH A 2-4 FT EASTERLY BACKSWELL PERSISTING
WITHIN THE SPECTRUM. STILL...SEAS WILL FALL THROUGH THE
WKND...BECOMING 2-4 FT ON SUNDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ017-023-024-
032-033-039-053>056.
NC...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ087-096-099-
105>110.
MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR AMZ250-252-254-
256.
&&
$$
NEAR TERM...REK/RJD
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...DL
MARINE...REK/RJD/JDW/RGZ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
348 AM CST WED MAR 6 2013
.SHORT TERM...TODAY THROUGH THURSDAY...
THE MAIN CHALLENGE FOR THE SHORT TERM IS THE EVOLUTION OF THE
STRATUS TODAY WITH DENSE FOG NORTH CENTRAL ALSO HIGHLIGHTING THE
PERIOD THIS MORNING. THE 00 UTC GUIDANCE IS IN GOOD AGREEMENT AND
FAVORED A BLEND FOR MOST FIELDS WITH BIAS CORRECTION PREFERRED FOR
HIGH TEMPERATURES TO CAPTURE THE IMPACT OF THE SNOWPACK. THE MAIN
CORRECTION BEING A REDUCTION OF A COUPLE DEGREES NORTH CENTRAL AND
AN INCREASE OF A FEW DEGREES SOUTHWEST AND SOUTH CENTRAL.
MAINTAINED THE DENSE FOG ADVISORY THROUGH 15 UTC ACROSS NORTH
CENTRAL NORTH DAKOTA AS SURFACE OBSERVATIONS AND WEBCAMS CONTINUE
TO INDICATE WIDESPREAD DENSE FOG WITH VISIBILITIES OF ONE QUARTER
MILE OR LESS IN THE STRATUS FREE AREAS AS OF 0930 UTC. AS MIXING
INCREASES IN THE 12-15 UTC TIME FRAME IN RETURN FLOW ON THE WESTERN
PERIPHERY OF THE DEPARTING SURFACE HIGH...THE FOG SHOULD QUICKLY
LIFT.
OTHERWISE FOR TODAY AS IS USUALLY THE CASE WITH STRATUS...THE
QUESTION IS HOW LONG IT WILL REMAIN IN PLACE. THE RAP THROUGH THE
OVERNIGHT HAS HAD A GOOD HANDLE ON THE DECKS ACROSS WESTERN
THROUGH SOUTH CENTRAL NORTH DAKOTA AND ACROSS THE EASTERN PORTIONS
OF THE STATE. THUS...WILL FOLLOW ITS LATEST RUNS FOR CLOUD COVER
TODAY...WHICH HOLDS THE STRATUS FIELDS THROUGH THE MORNING AND
SLOWLY LIFTS THEM THROUGH THE AFTERNOON. DID ADD A MENTION OF
ISOLATED FLURRIES UNDER THE STRATUS BASED ON OBSERVED TRENDS UNDER
THE DECK THROUGH THE NIGHT. WITH SOUTHEASTERLY WINDS...A LOW LEVEL
INVERSION WILL SETUP ACROSS THE AREA...LIMITING MIXING HEIGHTS AND
HIGH TEMPERATURES. GIVEN THE COLD START NORTH CENTRAL THIS MORNING
AND THE FRESH SNOW...HIGHS ARE ONLY EXPECTED TO CLIMB INTO THE
TEENS. ACROSS THE THINNER SNOWPACK OF THE SOUTHWEST...BELIEVE
HIGHS IN THE LOWER 30S ARE POSSIBLE ACROSS THE HIGHER TERRAIN AS
MORE AND MORE BARE GROUND BECOMES EXPOSED THROUGH THE DAY.
FOR TONIGHT...A TIGHT PRESSURE GRADIENT BETWEEN THE AFOREMENTIONED
DEPARTING HIGH AND LOW PRESSURE ACROSS NORTHEAST WYOMING WILL
MAINTAIN SOUTHEASTERLY WINDS AROUND 15 KTS FOR MUCH OF THE AREA
OVERNIGHT. THUS...TEMPERATURES SHOULD NOT FALL TOO FAR...WITH LOWS
NEAR 10 NORTHEAST TO THE UPPER 20S SOUTHWEST.
ON THURSDAY A WARM FRONT PROPAGATES INTO WESTERN NORTH DAKOTA AND
IS FORECAST TO MAKE IT THROUGH THE HIGHWAY 83 CORRIDOR BY LATE
AFTERNOON. FAVORING BIAS CORRECTION TO AID IN THE SNOWPACK
IMPACTS...HIGHS SHOULD RANGE FROM THE MID 20S ACROSS THE TURTLE
MOUNTAINS TO UPPER 30S SOUTH CENTRAL AND POSSIBLY THE LOWER 40S
SOUTHWEST AS INSOLATION FROM TODAY...BREEZY CONDITIONS THROUGH THE
OVERNIGHT AND MILD TEMPERATURES ON THURSDAY SHOULD ALL ACT TO
QUICKLY EVAPORATE/MELT THE SNOW ACROSS THE SOUTHWEST AND SOUTH
CENTRAL. THERE IS A SLIGHT CHANCE OF SNOW MAINLY ALONG AND NORTH
OF US HIGHWAY 2 ON THURSDAY AS AN UPPER LEVEL WAVE EJECTS OUT OF
THE INTERMOUNTAIN WEST. HOWEVER...THE 00 UTC GUIDANCE HAS TRENDED
FURTHER NORTH WITH ANY PRECIPITATION COMPARED TO EARLIER RUNS.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
THE MAIN FOCUS OF THE LONG TERM PERIOD IS THE POTENTIAL FOR ANOTHER
ROUND OF SNOW ON FRIDAY...POSSIBLY LINGERING INTO SATURDAY. MODEL
CONSENSUS IS STRONGER TODAY WITH THE LATEST SUITE OF
MODELS...REGARDING THE EVOLUTION OF A LARGE WESTERN CONUS TROUGH
THROUGH THE PLAINS. CONFIDENCE IS INCREASING IN THE POTENTIAL FOR
LIGHT SNOW FRIDAY AFTERNOON AND NIGHT...MAINLY OVER SOUTHERN AND
CENTRAL PORTIONS OF THE FORECAST AREA. LATEST WPC GUIDANCE AROUND A
COUPLE INCHES THROUGH 12Z SATURDAY SEEMS REASONABLE AT THIS POINT.
THERE IS STILL UNCERTAINTY AS TO HOW FAST THE TROUGH WILL EXIT ON
SATURDAY...AS THE ECMWF/GFS ARE FASTER AND THE GEM/NAM SUGGEST
ADDITIONAL SNOW ACROSS THE SOUTHEAST. HAVE OPTED TO STICK WITH THE
FASTER SOLUTIONS AND KEEP CHC POPS LIMITED TO THE FAR SE COUNTIES ON
SATURDAY. LOOKING AHEAD...DEVELOPING NORTHWEST FLOW LATE IN THE
PERIOD WILL LIKELY RESULT IN PERIODS OF SHORTWAVE ENERGY STREAMING
INTO THE STATE...BUT TIMING DIFFERENCES MAKE IT DIFFICULT TO FOCUS
ON ANY PARTICULAR PERIOD RIGHT NOW.
&&
.AVIATION...
MVFR/IFR STRATUS CONTINUES TO EXPAND ACROSS WESTERN AND CENTRAL NORTH
DAKOTA EARLY THIS MORNING...AND IS NOW IMPACTING ALL TAF SITES.
DENSE FOG HAS ALSO DEVELOPED AT KMOT AND WILL LIKELY PERSIST UNTIL
THE LOW CLOUD SHIELD MOVES IN. EXPECT A FEW FLURRIES THROUGH THE
MORNING AS WELL. MVFR CIGS SHOULD LINGER AT KJMS/KDIK THROUGH THE
AFTERNOON...WITH DECREASING CLOUDS AT KBIS/KISN/KMOT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR NDZ002>005-
011>013-021>023.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...RK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
104 AM CST WED MAR 6 2013
.DISCUSSION...
NO SIGNIFICANT CHANGES WERE REQUIRED WITH THIS FORECAST UPDATE AS
THE INHERITED FORECAST WAS WELL ON TRACK AND BLENDED TO THE 0630
UTC OBSERVED TRENDS.
SURFACE HIGH PRESSURE WAS IN PLACE ACROSS NORTH CENTRAL NORTH
DAKOTA AND INTO THE JAMES RIVER VALLEY. WITH FRESH SNOW AND CLEAR
SKIES...SUB-ZERO TEMPERATURES ARE BEING OBSERVED WITHIN THE
CENTER OF THE SURFACE HIGH. FOLLOWED CLOSELY TO THE LATEST RAP RUNS
FOR OVERNIGHT LOWS AS IT HAS A GOOD HANDLE ON THE TEMPERATURE
PATTERN THUS FAR THROUGH THE EARLY OVERNIGHT. THE BIGGEST
CHALLENGE FOR TONIGHT WILL BE THE EVOLUTION OF THE STRATUS ACROSS
WESTERN AND INTO SOUTH CENTRAL NORTH DAKOTA...WITH A BREAK IN THE
DECK UNTIL THE DEVILS LAKE BASIN AND EASTERN PORTIONS OF THE JAMES
RIVER VALLEY. AS HAS BEEN THE CASE...THE RAP ALSO HAS A GOOD
HANDLE ON THE STRATUS AND WILL FOLLOW ITS LOW LEVEL MOISTURE
FIELDS FOR CLOUD COVER THE REMAINDER OF THE NIGHT.
FINALLY...INCREASED THE WORDING FROM PATCHY FOG TO AREAS OF DENSE
FOG ACROSS THE NORTHWEST AND NORTH CENTRAL BASED UPON SURFACE
OBSERVATIONS AND WEBCAMS.
&&
.AVIATION...FOR THE 06Z WEDNESDAY TAF ISSUANCE...ONE STRATUS AREA
WITH MVFR CIGS STRETCHING FROM KISN TO KDIK...WHILE A SECOND AREA WAS
LOCATED OVER KJMS WITH FLURRIES AND OCCASIONAL REDUCTION TO MVFR
VSBYS. STRATUS WAS LOCATED JUST WEST OF KBIS...WITH SKC IN KMOT.
PATCHY FOG IS POSSIBLE AT KBIS/KMOT OVERNIGHT...WHILE STRATUS IS
FORECAST TO CONTINUE ELSEWHERE AND SLOWLY EXPAND THROUGH 12Z.
OVERALL...EXPECT MVFR CIGS AND PATCHY FOG TO PERSIST THROUGH MOST OF
WEDNESDAY MORNING. THE MVFR CIGS WILL SLOWLY IMPROVE TO LOW VFR
WEDNESDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
AVIATION...KS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
108 AM EST WED MAR 6 2013
.SYNOPSIS...
LOW PRESSURE PUSHES THROUGH OVERNIGHT...CHANGING RAIN TO SNOW. SNOW
ON ITS BACKSIDE WEDNESDAY. UPSLOPE SNOW UNDER NORTHWEST FLOW INTO
THE END OF THE WEEK NORTHEAST MOUNTAINS. HIGH PRESSURE BY WEEKEND.
&&
.NEAR TERM /UNTIL 9 AM THIS MORNING/...
UPDATED WIND DIRECTION...SPEED AND GUST AFTER EXTRAPOLATING SFC
LOW CENTER FROM THE RUC TO MATCH SFC OBS AND RADAR LOOP. REST OF
FORECAST REMAINS ON TRACK WITH PCPN CHANGING TO ALL SNOW BY
05Z.
PREVIOUS FORECAST BELOW...
930 PM UPDATE...
NEAR TERM TRENDS INCLUDING FASTER FALL ON TEMPERATURES WARRANT
STARTING THE ADVISORY FOR CENTRAL WV MOUNTAINS AND THE NORTHERN WV
LOWLANDS EARLIER. ALSO HAVE SLIGHTLY HIGHER SNOWFALL AMOUNTS FOR
THE NORTHERN MOUNTAINS OVERNIGHT GIVEN LOWER TEMPERATURES THERE.
ENHANCED WIND GUSTS TUG FORK / COAL FIELDS AREA AND EVEN INTO THE
HTS TRI-STATE AREA...ALL S OF THE LOW TRACK.
630 PM UPDATE...
COMPLEX FCST BY AND LARGE ON TRACK AS LOW PRESSURE ENTERS THE AREA
ALONG THE OHIO RIVER.
PREV DISCN...
PRECIPITATION SLOW IN PUSHING INTO THE CWA AFTER THE FIRST BATCH
DISSOLVED OUT SO...TRIMMED BACK SOME OF THE POPS OVER THE NORTHERN
ZONES OVER THE NEXT FEW HOURS UNTIL SHIELD ACCELERATES THROUGH. USED
THE LOCAL WRF MODELS TO ACCOUNT FOR THIS TIMING.
BIGGEST KEYS TO THE FORECAST TODAY ARE THE TIMING OF THE TEMPERATURE
DROPS TO AND BELOW FREEZING TONIGHT AND THE POTENTIAL OF LOW LEVEL
SUBSIDENCE OVER THE LOWLANDS NEAR 12Z WEDNESDAY. REGARDING THE
FORMER...MODELS WERE VERY SLUGGISH IN BRINGING THE TEMPERATURES DOWN
TO FREEZING FOR THE TRANSITION TO FROZEN PRECIPITATION. WEARY OF
THIS TEMPERATURE GUIDANCE UNDERDOING THE DYNAMIC COOLING ASPECT...SO
NUDGED THE HOURLIES DOWN A COUPLE DEGREES DURING THE TONIGHT TIME
PERIOD. THIS DOES NOT INCLUDE THE MOUNTAINS...AS THESE LOCATIONS
WERE COOL ENOUGH.
AS THE SNOWFALL BEGINS...WILL HAVE THAT LAG PERIOD WHERE RAIN AND
SLOWLY COOLING AIR WILL HINDER ACCUMULATIONS. COULD START AS SLUSHY
ACCUMULATIONS AT FIRST...ESPECIALLY FOR THE LOWLANDS. TRANSITION FOR
THE HIGHER ELEVATIONS AND SUBSEQUENT ACCUMULATIONS LOOKS TO BE MORE
EFFICIENT. BUT THERE WILL STILL BE A HEAVY AND WET NATURE TO THE
SNOW.
GFS AND NAM DEPICT SUBSIDENCE AT THE 700MB...AND VERY LITTLE LIFT AT
850MB OVER THE LOWLANDS...PARTICULARLY THE TRI STATE AREA.
THEREFORE...FEEL THE BULK OF THE SNOW...WHICH ARE GENERALLY AN INCH
OR LESS OVER THE CHARLESTON TO HUNTINGTON CORRIDOR...WILL FALL PRIOR
TO 12Z. POPS COME DOWN TO CHANCE AT THIS TIME. THIS IS NOT THE CASE
FOR THE NORTHERN TIER OF COUNTIES AND ALONG AND INCLUDING THE
MOUNTAINS...WHERE ACCUMULATIONS WILL CONTINUE WELL INTO THE SHORT
TERM.
NO ADJUSTMENTS TO THE HEADLINES AT THIS TIME.
&&
.SHORT TERM /9 AM THIS MORNING THROUGH THURSDAY NIGHT/...
PRECIPITATION SHOULD MAINLY BE IN THE FORM OF SNOW BY THE
START OF THE SHORT TERM PERIOD...AS UPPER LOW MOVES OFF TO THE SOUTH
AND EAST OF THE CWA. STILL EXPECTING SOME DECENT
ACCUMULATIONS...MAINLY IN THE 12Z TO 18Z TIME FRAME...AS MODELS
INDICATING GOOD DENDRITE GROWTH AND DYNAMICS CONTINUING DURING THIS
PERIOD. HOWEVER...AS THE DAY PROGRESSES...AND THE LOW PULLS FURTHER
AWAY...THIS WILL CHANGE AS MOISTURE DEPTH AND DYNAMICS DECREASE. MAY
EVEN SEE A TRANSITION TO DZ OR FZDZ LATER ON WEDNESDAY ACROSS SOME
OF THE LOWLANDS IN PARTICULAR AS LAYERS ABOVE 700MB GRADUALLY DRY
OUT. FOR NOW THOUGH...WILL JUST TRANSITION TO LIGHT SNOW SHOWERS
WITH LITTLE TO NO ACCUMULATIONS ACROSS LOWLANDS...WITH LIGHT
ADDITIONAL ACCUMULATIONS ACROSS MOUNTAIN ZONES IN THE NW UPSLOPE
FLOW.
IN ADDITION TO PRECIPITATION...STILL LOOKING AT DECENT WINDS
DEVELOP...PARTICULARLY ACROSS MOUNTAINOUS COUNTIES AS PRESSURE
GRADIENT TIGHTENS...AND STRONGER WINDS ALOFT DEVELOP. AS STATED IN
PREVIOUS FORECASTS...THIS WILL BE A RATHER HEAVY WET SNOW DURING THE
PERIOD.
AS THE LOW CONTINUES TO PULL OFF TO THE EAST ON WEDNESDAY...WILL SEE
A TRANSITION TO LIGHT UPSLOPE SNOW SHOWERS...WITH ADDITIONAL LIGHT
ACCUMULATIONS EXPECTED.
GUIDANCE SEEMS TO BE RUNNING A LITTLE HIGH DURING THE
PERIOD...PARTICULARLY ON WEDNESDAY MAX T...AND ELECTED TO KEEP
TEMPERATURES BELOW GUIDANCE ON THIS DAY AS LOW WILL CONTINUE TO PUSH
TO SOUTH AND EAST...BRINGING IN COLDER AIR...AND AS PLENTY OF CLOUD
COVER WILL LINGER DURING THE DAY WEDNESDAY. DESPITE REMAINING BELOW
GUIDANCE...DO HAVE MUCH OF THE LOWLAND COUNTIES INCHING ABOVE
FREEZING ON WEDNESDAY.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
MODELS SHOWING UPSLOPE SNOW SHOWERS ENDING IN THE MOUNTAINS ON
FRIDAY. HIGH PRESSURE THEN BUILDS IN FOR THE BEGINNING OF THE
WEEKEND. MODELS HAVE A LOT OF SPREAD WITH TIMING OF THE NEXT SYSTEM
EARLY NEXT WEEK. USED A ECMWF/GEFS ENSEMBLE MEAN BLEND...WHICH PUTS
THE TIMING BETWEEN THE GFS AND ECMWF.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
PCPN HAS CHANGED TO ALL SNOW ACROSS THE ENTIRE AREA BY 05Z.
PERIODS OF IFR UNDER BURSTS OF SNOW ARE LIKELY TO SPREAD FROM
SOUTH TO NORTH AS THE LOW PRESSURE MOVE ROUGHLY NORTHEAST ACROSS
PKB THROUGH 12Z. OTHERWISE...MVFR UNDER LIGHT SNOW WILL PREVAIL
THROUGH 09Z...DETERIORATING THROUGH 12Z. BIG CHALLENGE TO FORECAST
WIND DIRECTION AS WIND WILL CONTINUALLY BACK AS THE LOW MOVES
ACROSS. GUSTY WINDS ARE ALSO LIKELY IN THE PERIPHERY OF THE LOW
CENTER...BEING WEAKER ALONG THE CENTERS TRACK AND AT PROTECTED
MOUNTAIN VALLEYS SUCH AS EKN.
THE PRECIPITATION WILL BECOME LIGHTER AND MORE INTERMITTENT WED
MORNING...ALLOWING VSBYS TO IMPROVE TO MVFR AT LEAST AT TIMES WED
MORNING. CIGS AND VSBYS MAY IMPROVE TO VFR ALONG AND W OF THE OHIO
RIVER BY LATE WED AFTERNOON...WHILE MVFR VSBYS AND CIGS REMAIN IN
THE MOUNTAINS IN SNOW SHOWERS.
SOUTH OF THE LOW...GUSTY SOUTHEAST FLOW WILL BECOME SOUTHWEST OVERNIGHT
AND THEN GUSTY NORTHWEST WED MORNING. GUSTY NORTHWEST FLOW THROUGHOUT
THE AREA WED AFTERNOON.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: WIND DIRECTIONS AND SPEEDS WILL BE HIGHLY
VARIABLE...AND COULD BE INCONSISTENT FROM HOUR TO HOUR. CEILINGS
COULD BOUNCE FROM MVFR TO IFR AS WIND SPEEDS AND INTENSITY OF SNOW CHANGE.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE WED 03/06/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12
CRW CONSISTENCY L L L L L L L L L L H H
HTS CONSISTENCY M M M M M M M L H H H H
BKW CONSISTENCY L L L L M M M M M M L L
EKN CONSISTENCY M M M M M M M M M M M M
PKB CONSISTENCY L L M M M M M L L H H H
CKB CONSISTENCY M M M M M M M M M M M M
AFTER 06Z THURSDAY...
IFR VISIBILITIES AND CEILINGS POSSIBLE IN SNOW SHOWERS WED NT INTO
THU...ESPECIALLY IN THE WV MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
WVZ009>011-019.
WINTER WEATHER ADVISORY UNTIL 1 AM EST THURSDAY FOR WVZ020-028-
030>032-035>037-039-040.
WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR WVZ038-046-
047.
OH...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
OHZ066-067-075-076.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/RPY/SL/26
NEAR TERM...ARJ/TRM/26
SHORT TERM...SL
LONG TERM...RPY
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1220 AM EST WED MAR 6 2013
.SYNOPSIS...
A WINTER STORM WILL AFFECT THE AREA TONIGHT AND EARLY WEDNESDAY.
HIGH PRESSURE WILL BUILD ACROSS THE REGION LATE THIS WEEK...LASTING
INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MADE SOME MINOR TWEAKS TO STORM TOTAL SNOW AND MADE ADJUSTMENTS TO
THE WEATHER GRIDS DURING THIS EVENING UPDATE. ALSO INCREASED WINDS
ACROSS THE SOUTH AND WEST AS SURFACE PRESSURE GRADIENT HAS
INCREASED ACROSS THE SOUTH...AND WILL LATER TONIGHT ACROSS THE
WEST. THIS WILL PRODUCE GUSTS OVER 30 MPH AT TIMES DURING THE
OVERNIGHT PERIOD FOR THOSE ZONES. RAIN/SNOW LINE HAS PROGRESSED TO
JUST WEST OF THE COLUMBUS AREA. PRECIPITATION WILL CONTINUE TO
TRANSITION TO SNOW ACROSS THE FAR EASTERN ZONES TOWARD
MIDNIGHT...WITH ALL SNOW FOR THOSE ZONES BY MIDNIGHT. HAVE HAD
REPORTS OF ISOLATED THUNDER ASSOCIATED WITH A STRONGER SNOW BAND
EXTENDING FROM DARKE COUNTY...SOUTHEASTWARD ACROSS WARREN COUNTY.
THESE THUNDER OCCURRENCES ARE ISOLATED IN NATURE.
THEREFORE...WILL HOLD OFF ON ADDING THE MENTION OF IT IN THE GRIDS
ATTM. THE PEAK SNOW INTENSITY WILL BE FROM NOW UNTIL A COUPLE OF
HOURS AFTER MIDNIGHT...AS THE BEST LIFT PRODUCES THE HIGHEST RATES
OF ACCUMULATION IN OUR AREA.
.PREVIOUS DISCUSSION AT 423 PM EST...
AN UPPER LOW IS DIVING SOUTHEASTWARD OUT OF THE NORTHERN PLAINS
AND INTO THE TENNESSEE VALLEY THIS EVENING. A SURFACE LOW
DEVELOPING OVER KENTUCKY...OUT AHEAD OF THE UPPER LOW WILL DEEPEN
AND PIVOT NORTHEASTWARD OVER THE OHIO VALLEY AS THE UPPER LOW
SLIDES BY TO THE SOUTH TONIGHT. PRECIPITATION IS ALREADY SPREADING
NORTHWARD ACROSS THE FORECAST AREA AHEAD OF THE INTENSIFYING
SURFACE LOW. PRECIPITATION WILL FALL AS RAIN ACROSS THE AREA INTO
THE EARLY EVENING...AS WARM AIR IS DRAWN NORTH AND WEST INTO THE
LOW LEVELS AROUND THE LOW.
THE FORECAST FOR LATER THIS EVENING BECOMES COMPLICATED...AS COLD
AIR BEGINS TO WORK ITS WAY BACK INTO THE LOW. THIS PROCESS WILL BE
TWOFOLD. LOW LEVEL COLD ADVECTION WILL ALLOW FOR COLDER AIR TO
WRAP INTO THE SURFACE LOW. AT THE SAME TIME...ABUNDANT VERTICAL
MOTION WILL PROVIDE FOR DYNAMIC COOLING FROM THE MIDDLE
LEVELS...PROPAGATING TO THE SURFACE. MODELS ARE IN AGREEMENT ON
THE STRONG VERTICAL MOTION ASSOCIATED WITH THIS SYSTEM THIS
EVENING ACROSS OUR AREA. HOWEVER...THERE ARE CRITICAL DIFFERENCES
IN HOW THE MODELS ARE HANDLING THE BATTLE BETWEEN DYNAMIC
COOLING...AND WARM AIR BEING PULLED IN AROUND THE LOW. BASED ON
HOW STRONG ASCENT IS AS HEAVIER PRECIPITATION MOVES IN THIS
EVENING...THIS FORECAST PACKAGE WENT WITH A MODERATELY FAST
CHANGEOVER TO SNOW TO BEGIN IN THE WESTERN ZONES AROUND 7
PM...SPREADING EAST THROUGH THE DAYTON/CINCY AREAS BY 9 PM...THEN
COLUMBUS BY 10 OR 11 PM. IF THE DYNAMIC COOLING PROCESS IS
STRONGER THAN THIS FORECAST IS HINTING AT...THEN THIS CHANGEOVER
WILL OCCUR SOONER...WITH THE RESULT BEING HIGHER SNOW TOTALS. OF
COURSE...IF ADDITIONAL WARMER AIR IS DRAW INTO THE SYSTEM...LIKE
THE RAP SUGGESTS THEN MORE RAIN WILL FALL INITIALLY. THE RAP
SOLUTION HAS BEEN ON THE WARM SIDE TODAY...THEREFORE AM LEANING
TOWARD THE COLDER SOLUTIONS.
ANY SNOW THAT OCCURS JUST AFTER THE CHANGEOVER WILL BE A
HEAVY...WET SNOW. THE BOTTOM LINE IS THAT THE MODELS LOOK AS IF
THEY ARE PICKING UP ON THE STRONGER LIFT BASED ON QPF AMOUNTS
RISING OVER RECENT RUNS. THIS MEANS A POTENTIAL FOR HIGHER STORM
TOTALS FOR OUR AREA. TOTAL SNOWFALL NUMBERS WERE THEREFORE TWEAKED
SLIGHTLY HIGHER...WITH THE MAXIMUM BEING AROUND 8 INCHES STORM
TOTAL ACROSS THE NORTHWESTERN ZONES. SOME OF THE SOUTHWESTERN
ZONES...WHERE A TRANSITION WILL OCCUR FIRST...MAY RECEIVE UP TO 4
INCHES OF SNOW. THE TRICKIEST SNOWFALL TOTAL FORECAST LIED WHERE
THE CENTER OF THE SURFACE LOW IS EXPECTED TO SPIN FOR A FEW HOURS
TONIGHT...ACROSS THE SCIOTO VALLEY. THERE...SNOWFALL AMOUNTS COULD
VARY QUITE A BIT...NOT ONLY DUE TO THE DELAYED CHANGEOVER DUE TO
SOME WARMER AIR...BUT THE LACK OF HEAVIER QPF UNDERNEATH THE LOW`S
CENTER LATE TONIGHT.
EXPANDED THE WINTER STORM WARNING TO INCLUDE SOME OUR OUR NORTHERN
KENTUCKY ZONES THAT ARE NOW EXPECTED TO REACH OUR 12 HOUR
CRITERIA OF 4 INCHES OF SNOW TONIGHT. DID DELAY THE START OF ALL
WARNINGS/ADVISORY EXCEPT ACROSS THE EXTREME NORTH...SINCE THAT
WARNING WAS ALREADY IN EFFECT AT THE TIME OF THE FORECAST PACKAGE
ISSUANCE.
SNOW WILL CONTINUE THROUGHOUT THE EARLY PRE-DAWN HOURS AS THE SURFACE
LOW SPINS ACROSS SOUTHEASTERN OHIO.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
THE UPPER LOW WILL QUICKLY SHIFT TOWARD THE MID ATLANTIC STATES
WEDNESDAY MORNING AS A SECONDARY SURFACE LOW DEVELOPS CLOSER TO
THE EASTERN SEABOARD. THIS ENERGY TRANSFER EASTWARD...AND AWAY
FROM OUR AREA WILL BRING A RAPID END TO FORCING SUPPORTING STEADY
SNOW IN OUR AREA. SNOW WILL TAPER OFF QUICKLY AROUND SUNRISE WITH
ONLY SOME LIGHTER SNOW SHOWERS EXPECTED DURING THE DAY.
NORTHERLY FLOW BEHIND THE DEPARTING STORM SYSTEM AND RIDGING
ACROSS THE NORTHERN PLAINS WILL KEEP A CHANCE FOR LIGHT SNOW OR
FLURRIES IN OUR AREA THROUGH WEDNESDAY NIGHT AND INTO THE DAY
THURSDAY. TEMPERATURES DURING THIS TIME PERIOD WILL REMAIN BELOW
NORMAL. LOW LEVEL MOISTURE...AND ASSOCIATED CLOUD COVER WILL
FINALLY BEGIN TO GIVE WAY TO DRIER CONDITIONS THURSDAY NIGHT...AS
THE RIDGE BUILDS ACROSS THE OHIO VALLEY. TEMPERATURES WILL LIKELY
BOTTOM OUT THURSDAY NIGHT IN THE UPPER TEENS TO LOW 20S UNDER
PARTLY CLOUDY SKIES.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AFTER A PLEASANT AND GENERALLY MILD WEEKEND...WITH GOOD MODEL
AGREEMENT...THERE IS CONSIDERABLE UNCERTAINTY ON A WEATHER SYSTEM
MOVING INTO THE REGION EARLY NEXT WEEK.
THE WEEKEND WILL BEGIN WITH A MID LEVEL TROUGH AXIS EXTENDING FROM
THE GULF OF MEXICO TO NORTHERN INDIANA. WARM ADVECTION WILL BE
UNDERWAY ALOFT...AND SHOULD BEGIN AT THE SURFACE AS WELL (AS WINDS
TAKE A SOUTHERLY COMPONENT). THIS PATTERN WILL GENERALLY CONTINUE
INTO SUNDAY...AS THE RIDGE AXIS MOVES EAST. WITH QUITE A BIT OF SUN
ON SATURDAY (PERHAPS JUST SOME LOW CLOUDS THAT ARE SLOW TO MOVE OUT
OF THE NORTHEASTERN CWA)...TEMPERATURES WILL RISE ABOVE NORMAL BY
ABOUT 5 DEGREES.
THE RIDGE WILL CONTINUE TO DOMINATE THE WEATHER ON SUNDAY...BUT AS
INFLUENCE FROM THE DEVELOPING WEATHER SYSTEM IN THE WESTERN STATES
BEGINS TO COMPLICATE THE FORECAST...SOME UNCERTAINTY WILL BEGIN TO
SET IN. MOISTURE WILL BEGIN TO ADVECT IN ALOFT...LEADING TO HIGH
CLOUDS THICKENING THROUGH THE DAY. DESPITE THIS...SURFACE WARM
ADVECTION WILL BE STRENGTHENING...LEADING TO EVEN WARMER TEMPS ON
SUNDAY.
BEYOND SUNDAY...A VERY HIGH AMOUNT OF UNCERTAINTY EXISTS IN THE
FORECAST. IT APPEARS CERTAIN THAT A WESTERN TROUGH WILL EJECT INTO
THE EASTERN STATES...AS SURFACE LOW PRESSURE DEVELOPS AND MOVES
THROUGH OR NEAR THE OHIO VALLEY. HOWEVER...THERE IS VERY LOW
CONFIDENCE IN THE TIMING OF THIS SYSTEM...AS WELL AS IN THE
PLACEMENT OF THE SURFACE LOW. DETERMINISTIC MODELS (12Z GFS VS 12Z
CMC VS 00Z ECMWF) ARE AS MUCH AS A DAY AND A HALF OFF IN
TIMING...WITH THE SURFACE LOW POSSIBLY GOING NORTH OR SOUTH OF THE
AREA. SO...AT THIS TIME...THE FORECAST WILL REMAIN VERY GENERAL.
ALTHOUGH IT IS FRUSTRATING TO GO NO HIGHER THAN 30 POPS WHEN RAIN
APPEARS A VIRTUAL CERTAINTY AT SOME POINT IN THE SUNDAY NIGHT
THROUGH TUESDAY TIME FRAME...THE TIMING DIFFERENCES ARE TOO GREAT TO
GO HIGHER.
&&
.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
A DYNAMIC STORM SYSTEM WILL CONTINUE TO AFFECT THE REGION THROUGH
12Z WITH SNOW AND WIND. SURFACE LOW PRESSURE OVER SOUTHEAST OHIO
THIS MORNING WILL BEGIN TO WEAKEN OVER SOUTHEAST OHIO BETWEEN 09Z
AND 12Z AS PARENT UPPER LEVEL LOW PUSHES EAST TOWARD THE MID
ATLANTIC...ALLOWING A STRONGER SURFACE LOW DEVELOP NEAR THE COAST.
THIS IS THE TYPICAL ENERGY TRANSFER WE SEE IN THE OHIO VALLEY.
SNOW...MODERATE TO LOCALLY HEAVY AT TIMES...SHOULD QUICKLY TAPER
OFF FROM NW TO SOUTHEAST BY SUNRISE. CONDITIONS WILL REMAIN CLOSE
TO AIRFIELD MINIMUMS UNTIL THE SNOW TAPERS OFF. THEREAFTER...SKIES
WILL REMAIN MOSTLY CLOUDY TO CLOUDY WITH VSBYS IMPROVING TO VFR
AND CEILINGS REMAINING IN THE MVFR RANGE BETWEEN 1500 AND 2000
FEET. GUSTY NORTH WINDS WILL BEGIN TO TAPER OFF TOWARD 00Z
THURSDAY.
OUTLOOK...MVFR CEILINGS TO LINGER INTO THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR OHZ026-
034-035-042>046-051>056-060>065-070>072-077>080.
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
OHZ073-074-081-082-088.
KY...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
KYZ089>093.
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
KYZ094>100.
IN...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR INZ050-
058-059-066-073>075-080.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...HATZOS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
436 AM EST WED MAR 6 2013
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN OHIO WILL WEAKEN AS A SECONDARY LOW
DEVELOPS OVER THE SOUTHERN MID-ATLANTIC PIEDMONT EARLY THIS
MORNING. THE LOW WILL TRACK SLOWLY NORTHEAST TO THE VIRGINIA
TIDEWATER REGION THIS AFTERNOON AND MOVE OFF THE DELMARVA
PENINSULA BY THIS EVENING. THIS COMPLEX STORM SYSTEM WILL BRING
MODERATE TO HEAVY SNOW TO SOUTH-CENTRAL PENNSYLVANIA. HIGH
PRESSURE WILL BUILD IN FROM THE WEST FOR THE WEEKEND WITH FAIR
WEATHER AND TEMPERATURES RISING TO NEAR NORMAL.
&&
.NEAR TERM /UNTIL 7 AM THIS MORNING/...
RADAR AND SATL LOOP SHOW WELL-DEFINED COMMA HEAD/DEFORMATION PCPN
BAND SPREADING NWD INTO SRN PA AS UPPER LOW AND ASSOCD HT FALLS
APPROACH THE SPINE OF THE N-CENTRAL APPALACHIANS. 06Z RUC SFC
ANALYSIS SHOWS PRIMARY/OCCLUDED LOW OVER SRN OH WITH SECONDARY LOW
DEVELOPING OVER THE NC/VA PIEDMONT IN RESPONSE TO 2-4MB 3HR PRES
FALLS. AS THE SECONDARY LOW BEGINS TO TRACK SLOWLY TO THE NE
EARLY THIS MORNING...EXPECT INCREASING FGEN FORCING TO SUPPORT
OCNL 1-1.5 IN/HR SNFL RATES OVR FAR SWRN/S-CENTRAL PA AS THE SNOW
BAND CONTINUES TO PUSH NORTH ACRS THE MASON DIXON LINE. ALTHOUGH
TEMPS ARE STILL A FEW DEGS ABOVE 32F IN SOME AREAS...EXPECT WET
BULB/NOCTURNAL EFFECTS AND ISALLOBARIC FORCING/COLDER NLY FLOW TO
RESULT IN ALL SNOW PTYPES. EXTRAPOLATION OF RADAR TRENDS ALONG
WITH CONSENSUS OF HI-RES MDLS SHOWS THE NRN EDGE OF THE SNOW CONFINED
ALONG AND SOUTH OF IDI-LNS LINE THRU AT LEAST THE NEXT FEW
HOURS/09Z WITH A SLIGHT NWD SHIFT LKLY BY 12Z. A VERY SHARP
GRADIENT WILL MAKE FOR A DIFFICULT SPATIAL FCST WITH SNOW/NO SNOW
OBS OVER A VERY SHORT N-S DISTANCE. EXPECT SEVERAL INCHES OF ACCUM
/2-4" IN 6 HRS/ BY DAYBREAK FROM SOMERSET COUNTY EWD TOWARD SOUTH
MTN.
&&
.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM THURSDAY/...
GUIDANCE CURRENTLY TRENDING A LITTLE FARTHER TO THE SOUTH AND
FURTHER DECREASES PRECIP AMOUNTS OVER THE AREA. BUT THIS COULD
JUST BE THE LATEST WAGGLE. HOWEVER...WE ARE FULLY INTO THE REALM
OF THE SHORT RANGE MODELS AT THIS MOMENT. SO...CONFIDENCE IS HIGH
ON THE AMOUNTS FROM A BLEND OF THE NAM/GFS/SREF. HEAVY SNOW MOST
LIKELY IN THE LAURELS AND ALONG THE MD BORDER WHERE THE HIGHEST
INFLUX OF MSTR FROM THE EAST IS POINTED. THE TREMENDOUS EASTERLY
FLOW WILL CREATE A HIGHLY ANOMALOUS 8H POSITIVE MOISTURE FLUX AREA
OVER THE SRN COUNTIES DURING THE MORNING AND EARLY AFTN IN OUR
SRN COS. THE EXPECTED MESOSCALE HEAVY BANDS OF SNOW WILL BE
CAPABLE OF MAKING INCH OR MORE PER HOUR RATES. SO EVEN A SHORTER
TIME IN THE FAVORED SNOWFALL PERIOD - NOW MORE LIKE 12-18HRS
RATHER THAN A FULL 24 HRS - KEEPS US JUST AS LIKELY TO GET 6 INCHES
OR MORE OF ACCUM ACROSS THE SOUTH.
THE STORM CENTER WILL BE ALMOST FULLY TRANSITIONED TO THE
SECONDARY CENTER AT THE BEGINNING OF THE PERIOD. THE TRACK MADE BY
THE STRONG CONSENSUS OF THE DETERMINISTIC MDLS AND ENSEMBLE
MEMBERS TAKES IT OUT TO SEA FAR ENOUGH BY WED NIGHT TO DECREASE
THE POPS IN THE WEST WED AFTN...AND IN THE EAST AROUND MIDNIGHT.
HOWEVER...A POSSIBLE NORTHWARD CURVE TO THE STORM WEDNESDAY
EVENING WHEN IT IS WELL OF THE COAST COULD DELAY THE EXIT OF VERY
LIGHT PRECIP FROM THE EASTERN COUNTIES UNTIL LATE WED NIGHT.
TEMPS ARE AN INTERESTING PART OF THIS FCST - WITH WIDESPREAD
30-33F TEMPS AS THE PRECIP OCCURS. THIS WILL LIKELY CREATE A
SOMEWHAT ELEV-DEPENDENT SNOW FALL. LANCASTER CO AND THE LOWER
ELEVS OF YORK/DAUPHIN/LEBANON CO WILL BE MOST AT-RISK TO SEE A
LITTLE RAIN MIX IN LATE WED/EARLY WED NIGHT. WILL DRAW SNOW ACCUM
MAP MORE BROAD- BRUSHED THOUGH FOR SIMPLICITY/S SAKE. THIS ALSO
KEEPS A VERY STRONG CONTINUITY IN THE FORECAST SNOW AMOUNTS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
LARGE STORM SYSTEM SLIDES OFF EAST COAST BY THURSDAY...WHILE A
CHILLY AND RATHER GUSTY NORTHERLY FLOW ARRIVES WITH ISOLATED TO
SCATTERED MTN SNOW SHOWERS. AFTER THAT...HEIGHTS BEGIN TO RISE
ON FRI...WITH DAYTIME TEMPS MODERATING TO SEASONAL NORMALS
THROUGH THE WEEKEND.
WARMING TREND CONTINUES INTO EARLY NEXT WEEK...BUT WITH
SIGNIFICANT MODEL DIVERGENCE DEVELOPING IN LONGER TERM MODELS.
BUT GENERAL PATTERN KEEPS BROAD MILDER WESTERLY FLOW TO EASTERN
U.S. WITH A WEAKENING LOW LIFTING ACROSS THE NORTHEAST MON NIGHT
INTO TUE INCREASING CHANCES FOR PRIMARILY RAIN SHOWERS.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
SNOW SHOWERS ARE CURRENTLY STREAMING FROM THE SOUTH ENVELOPING PA
THIS MORNING. LIFR CONDITIONS AT JST AND AOO WILL CONTINUE THROUGH
THE FIRST HALF OF THE DAY...BEFORE SUBSIDING BY 18Z. EXPECT MVFR
TO IFR CIGS TO CONTINUE THROUGH MOST OF THE DAY. THE LOW LEVEL
MOISTURE COULD ALLOW FOR IFR AND LOWER CIGS TONIGHT.
ELSEWHERE THE SNOW IS CURRENTLY BRINGING MVFR CIGS AND VSBYS TO
MDT...AND MVFR CIGS OUT AHEAD OF THE SYSTEM AT UNV. IFR CONDITIONS
ARE EXPECTED AS THE SNOW INTENSIFIES THROUGH THIS MORNING AT
MDT...LNS. DUE TO THE MOVEMENT OF THE LOW...THESE SITES WILL
REMAIN BELOW VFR FOR THE LONGEST PERIOD DUE TO THIS STORM. EXPECT
IFR CIGS AND VSBYS POSSIBLE THROUGH 00Z. IPT AND UNV WILL HAVE
MVFR VSYBS TO IFR CIGS POSSIBLE THROUGH THE FIRST HALF OF THE DAY
BEFORE IMPROVING INTO THE EARLY EVENING. BFD WILL BE VFR THROUGH
MOST OF THE PERIOD...WITH ONLY SOME MVFR CIGS POSSIBLE OVERNIGHT
TONIGHT...AS THE FLOW SHIFTS TO THE NORTH. LOW LEVEL WIND- SHEAR
WILL ALSO BE POSSIBLE AS LOW LEVEL NORTHEAST FLOW QUICKLY CHANGES
AND INCREASES TO EASTERLY JUST OFF THE SURFACE.
EXPECT IMPROVING CONDITIONS FOR THU INTO SAT...AS HIGH PRESSURE
BUILDS EASTWARD.
OUTLOOK...
THU...MVFR/IFR -SHSN EARLY...BECOMING VFR.
FRI-SUN...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 2 AM EST THURSDAY FOR PAZ057>059.
WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR
PAZ024>026-033>036-063-064.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
PAZ027-028-056.
WINTER STORM WARNING UNTIL 2 AM EST THURSDAY FOR PAZ065-066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...DANGELO
LONG TERM...RXR/TYBURSKI
AVIATION...LA CORTE/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
128 AM EST WED MAR 6 2013
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN OHIO WILL WEAKEN AS A SECONDARY LOW
DEVELOPS OVER THE SOUTHERN MID-ATLANTIC PIEDMONT EARLY THIS
MORNING. THE LOW WILL TRACK SLOWLY NORTHEAST TO THE VIRGINIA
TIDEWATER REGION THIS AFTERNOON AND MOVE OFF THE DELMARVA
PENINSULA BY THIS EVENING. THIS COMPLEX STORM SYSTEM WILL BRING
MODERATE TO HEAVY SNOW TO SOUTH-CENTRAL PENNSYLVANIA. HIGH
PRESSURE WILL BUILD IN FROM THE WEST FOR THE WEEKEND WITH FAIR
WEATHER AND TEMPERATURES RISING TO NEAR NORMAL.
&&
.NEAR TERM /UNTIL 7 AM THIS MORNING/...
RADAR AND SATL LOOP SHOW WELL-DEFINED COMMA HEAD/DEFORMATION PCPN
BAND SPREADING NWD INTO SRN PA AS UPPER LOW AND ASSOCD HT FALLS
APPROACH THE SPINE OF THE N-CENTRAL APPALACHIANS. 06Z RUC SFC
ANALYSIS SHOWS PRIMARY/OCCLUDED LOW OVER SRN OH WITH SECONDARY LOW
DEVELOPING OVER THE NC/VA PIEDMONT IN RESPONSE TO 2-4MB 3HR PRES
FALLS. AS THE SECONDARY LOW BEGINS TO TRACK SLOWLY TO THE NE
EARLY THIS MORNING...EXPECT INCREASING FGEN FORCING TO SUPPORT
OCNL 1-1.5 IN/HR SNFL RATES OVR FAR SWRN/S-CENTRAL PA AS THE SNOW
BAND CONTINUES TO PUSH NORTH ACRS THE MASON DIXON LINE. ALTHOUGH
TEMPS ARE STILL A FEW DEGS ABOVE 32F IN SOME AREAS...EXPECT WET
BULB/NOCTURNAL EFFECTS AND ISALLOBARIC FORCING/COLDER NLY FLOW TO
RESULT IN ALL SNOW PTYPES. EXTRAPOLATION OF RADAR TRENDS ALONG
WITH CONSENSUS OF HI-RES MDLS SHOWS THE NRN EDGE OF THE SNOW CONFINED
ALONG AND SOUTH OF IDI-LNS LINE THRU AT LEAST THE NEXT FEW
HOURS/09Z WITH A SLIGHT NWD SHIFT LKLY BY 12Z. A VERY SHARP
GRADIENT WILL MAKE FOR A DIFFICULT SPATIAL FCST WITH SNOW/NO SNOW
OBS OVER A VERY SHORT N-S DISTANCE. EXPECT SEVERAL INCHES OF ACCUM
/2-4" IN 6 HRS/ BY DAYBREAK FROM SOMERSET COUNTY EWD TOWARD SOUTH
MTN.
&&
.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM THURSDAY/...
GUIDANCE CURRENTLY TRENDING A LITTLE FARTHER TO THE SOUTH AND
FURTHER DECREASES PRECIP AMOUNTS OVER THE AREA. BUT THIS COULD
JUST BE THE LATEST WAGGLE. HOWEVER...WE ARE FULLY INTO THE REALM
OF THE SHORT RANGE MODELS AT THIS MOMENT. SO...CONFIDENCE IS HIGH
ON THE AMOUNTS FROM A BLEND OF THE NAM/GFS/SREF. HEAVY SNOW MOST
LIKELY IN THE LAURELS AND ALONG THE MD BORDER WHERE THE HIGHEST
INFLUX OF MSTR FROM THE EAST IS POINTED. THE TREMENDOUS EASTERLY
FLOW WILL CREATE A HIGHLY ANOMALOUS 8H POSITIVE MOISTURE FLUX AREA
OVER THE SRN COUNTIES DURING THE MORNING AND EARLY AFTN IN OUR
SRN COS. THE EXPECTED MESOSCALE HEAVY BANDS OF SNOW WILL BE
CAPABLE OF MAKING INCH OR MORE PER HOUR RATES. SO EVEN A SHORTER
TIME IN THE FAVORED SNOWFALL PERIOD - NOW MORE LIKE 12-18HRS
RATHER THAN A FULL 24 HRS - KEEPS US JUST AS LIKELY TO GET 6 INCHES
OR MORE OF ACCUM ACROSS THE SOUTH.
THE STORM CENTER WILL BE ALMOST FULLY TRANSITIONED TO THE
SECONDARY CENTER AT THE BEGINNING OF THE PERIOD. THE TRACK MADE BY
THE STRONG CONSENSUS OF THE DETERMINISTIC MDLS AND ENSEMBLE
MEMBERS TAKES IT OUT TO SEA FAR ENOUGH BY WED NIGHT TO DECREASE
THE POPS IN THE WEST WED AFTN...AND IN THE EAST AROUND MIDNIGHT.
HOWEVER...A POSSIBLE NORTHWARD CURVE TO THE STORM WEDNESDAY
EVENING WHEN IT IS WELL OF THE COAST COULD DELAY THE EXIT OF VERY
LIGHT PRECIP FROM THE EASTERN COUNTIES UNTIL LATE WED NIGHT.
TEMPS ARE AN INTERESTING PART OF THIS FCST - WITH WIDESPREAD
30-33F TEMPS AS THE PRECIP OCCURS. THIS WILL LIKELY CREATE A
SOMEWHAT ELEV-DEPENDENT SNOW FALL. LANCASTER CO AND THE LOWER
ELEVS OF YORK/DAUPHIN/LEBANON CO WILL BE MOST AT-RISK TO SEE A
LITTLE RAIN MIX IN LATE WED/EARLY WED NIGHT. WILL DRAW SNOW ACCUM
MAP MORE BROAD- BRUSHED THOUGH FOR SIMPLICITY/S SAKE. THIS ALSO
KEEPS A VERY STRONG CONTINUITY IN THE FORECAST SNOW AMOUNTS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
LARGE STORM SYSTEM SLIDES OFF EAST COAST BY THURSDAY...WHILE A
CHILLY AND RATHER GUSTY NORTHERLY FLOW ARRIVES WITH ISOLATED TO
SCATTERED MTN SNOW SHOWERS. AFTER THAT...HEIGHTS BEGIN TO RISE
ON FRI...WITH DAYTIME TEMPS MODERATING TO SEASONAL NORMALS
THROUGH THE WEEKEND.
WARMING TREND CONTINUES INTO EARLY NEXT WEEK...BUT WITH
SIGNIFICANT MODEL DIVERGENCE DEVELOPING IN LONGER TERM MODELS.
BUT GENERAL PATTERN KEEPS BROAD MILDER WESTERLY FLOW TO EASTERN
U.S. WITH A WEAKENING LOW LIFTING ACROSS THE NORTHEAST MON NIGHT
INTO TUE INCREASING CHANCES FOR PRIMARILY RAIN SHOWERS.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
UPCOMING STORM STILL ON TRACK TO HAVE THE HIGHEST IMPACT ALONG
THE SOUTHERN TIER OF THE FCST AREA...WITH IMPACTS DECREASING OVER
CENTRAL AND NORTHERN PA.
SNOW IS INVADING SWRN AREAS AS OF 11 PM...AND WILL SPREAD
EASTWARD FOR THE REMAINDER OF THE OVERNIGHT. AS THE LOW MOVES OFF
TO OUR SOUTH AND INTENSIFIES LATE TONIGHT AND EARLY
WEDNESDAY...SNOW WILL INCREASE IN INTENSITY WITH RAPID
DETERIORATION TO IFR/LIFR VISIBILITIES TO BE EXPECTED. BEST CHANCE
OF IFR/LIFR WILL BE FROM JST EAST TO MDT/LNS. LOW LEVEL WIND-SHEAR
WILL ALSO BE POSSIBLE AS LOW LEVEL NORTHEAST FLOW QUICKLY CHANGES
AND INCREASES TO EASTERLY JUST OFF THE SURFACE.
ACROSS CENTRAL AND NORTHERN PENNSYLVANIA...SNOWFALL AND FLIGHT
CONDITIONS WILL BE LESS AFFECTED. MVFR TO OCCASIONAL IFR AT KUNV
POSSIBLY UP TO KIPT. KBFD WILL BE THE LEAST AFFECTED WITH VFR TO
OCCASIONAL MVFR AT TIMES IN MAINLY FLURRIES.
EXPECT IMPROVING CONDITIONS FOR THU INTO SAT...AS HIGH PRESSURE
BUILDS EASTWARD.
OUTLOOK...
THU...MVFR/IFR -SHSN EARLY...BECOMING VFR.
FRI-SUN...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 2 AM EST THURSDAY FOR PAZ027-028-
056>059.
WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR
PAZ024>026-033>036-063-064.
WINTER STORM WARNING UNTIL 2 AM EST THURSDAY FOR PAZ065-066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...DANGELO
LONG TERM...RXR/TYBURSKI
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1050 PM CST TUE MAR 5 2013
.DISCUSSION.../ISSUED AT 840 PM CST/
LARGE SWATH OF LOW STRATUS REMAINS LARGELY UNCHANGED FROM THIS
AFTERNOON...AS THE LOW LEVEL NORTH NORTHWEST FLOW CONTINUES TO
STREAM THE STRATUS ACROSS THE FORECAST AREA. SOME THINNING IS
OBSERVED ACROSS SOUTH CENTRAL SOUTH DAKOTA AND FAR NORTHEAST
NEBRASKA...BUT OVERALL...DO NOT ANTICIPATE MUCH IF ANY PUSH EASTWARD
TONIGHT. COULD SEE SOME THINNING IN THE WEST LATE TONIGHT AS THE
SURFACE RIDGE TRACKS THROUGH THE REGION...BUT WITH SUCH LIGHT FLOW
WE COULD VERY WELL SEE THE STRATUS HANG ON THROUGH WEDNESDAY
MORNING. WITH THE BULK OF THE FORECAST AREA LIKELY TO SEE
CONSIDERABLE CLOUD COVERAGE OVERNIGHT...HAVE RAISED LOWS A FEW
DEGREES.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
STRATUS HAS CONTINUED TO EXPAND WITH DECREASING WINDS AND DIRECTION
BECOMING MORE NORTHEASTERLY. MODELS NOT HANDLING THE STRATUS WELL
AT ALL...WITH THE RAP BEING THE ONLY MODEL SUGGESTING STRATUS
CURRENTLY EXISTS ACROSS THE AREA. HAVE KEPT STRATUS ACROSS THE AREA
THROUGH THE OVERNIGHT...WITH CEILINGS LOWERING SLIGHTLY AROUND
SUNRISE. MODEL SOUNDINGS SUGGEST OUTSIDE CHANCE OF STRATUS LOWERING
TO THE GROUND NEAR KHON...BUT CONFIDENCE NOT THERE AT THIS POINT TO
PUT INTO THE TAF. AT KFSD AND KSUX...STRATUS MAY DIP INTO THE IFR
RANGE BEFORE RECOVERING INTO THE MVFR CATEGORY. WILL BE HARD TO
SHAKE THE STRATUS TOMORROW WITH LIGHT SOUTHEASTERLY FLOW
DEVELOPING...AND KEPT STRATUS THROUGHOUT THE DAY. SOUNDINGS DON/T
HAVE MUCH TO WORK OFF OF BY TOMORROW EVENING...BUT KEPT STRATUS WITH
REINFORCING SOUTHEASTERLY FLOW.
&&
.PREV DISCUSSION.../ISSUED AT 300 PM CST/
WIDESPREAD STRATUS ALONG AND EAST OF THE JAMES RIVER WILL BE SLOW TO
CLEAR FROM WEST TO EAST OVERNIGHT. MODELS APPEAR TOO FAST IN
CLEARING THE STRATUS OUT AND WILL KEEP AREAS EAST OF I29 MOSTLY
CLOUDY OVERNIGHT WITH CLEARING TOWARDS MORNING. THIS SHOULD ALSO
HELP HOLD TEMPERATURES UP ACROSS THE EAST AND HAVE BUMPED LOWS UP
THERE 2 TO 4 DEGREES. THE BIG QUESTION FOR WEDNESDAY WILL BE THE
CLOUD COVER. IF STRATUS DOES NOT CLEAR ACROSS THE EAST LATER
TONIGHT...WEAK LOW LEVEL EASTERLY FLOW ON WEDNESDAY MAY KEEP THE
STRATUS IN ALL DAY AND WILL HOLD THE TEMPERATURES DOWN. AM NOT
CONFIDENT CLEARING WILL OCCUR SO WILL BE A TAD BIT MORE PESSIMISTIC
AND GO WITH PARTLY CLOUDY ACROSS THE EAST. WILL KEEP HIGHS GENERALLY
IN THE 20S EAST OF I29 AND IN THE 30S TO LOWER 40S WEST WITH THE
WARMEST TEMPERATURES ACROSS THE SOUTHWEST CWA.
EXPECT SKIES SHOULD FINALLY GO MOSTLY CLEAR...FOR A SPELL...
WEDNESDAY NIGHT AS SUBSIDENCE FROM THE HIGH AND A LIGHT EASTERLY
FLOW OF DRY AIR STARTING AS THE HIGH MOVES EAST WORK TOGETHER.
CLOUDS...THEY SHOULD BE MIDDLE AND HIGH...SHOULD LATER WORK THEIR
WAY SLOWLY BACK OVER THE AREA THURSDAY THROUGH FRIDAY IN WARMING
PATTERN. NO PRECIPITATION THREAT SEEN THESE TWO DAYS THROUGH FRIDAY
AFTERNOON. TEMPERATURES WILL WARM THOUGH SURFACE WARMING WILL LIKELY
BE LIMITED AS THE LOW LEVEL FLOW BEGINS TO BACK AGAIN TO MORE
EASTERLY FRIDAY AFTER GOING SOUTHERLY. GUIDANCE TEMPERATURES DO NOT
LOOK BAD. FOR NOW...CLOUD COVER AND DEVELOPING EASTERLY/SOUTHEAST
FLOW IS EXPECTED TO LIMIT THE CHANCE OF ANY LATE NIGHT FOG AFTER
DAYTIME SNOWMELT SO WILL KEEP OUT.
MEDIUM RANGE MODELS HAVE...FOR NOW...REACHED A CONSENSUS ON A
STRONGER CANADIAN NORTHERN STREAM KEEPING POTENTIALLY WET WEEKEND
SYSTEM MOSTLY TO THE SOUTH OF OUR AREA. THE EC IN PARTICULAR HAD
BEEN GOING ON THE NORTHERN TRACK AND WET SIDE FOR OUR AREA UP TO
TODAY. HAVE REACHED AGREEMENT WITH NEIGHBORS ON KEEPING PRECIP
MENTION BUT LOWERING POPS SOME FOR THE WEEKEND...THEN ALLOW FOR THE
CHASING OUT OF THE SYSTEM BY THE START OF NEXT WEEK. THE CANADIAN
RIDGING PARTLY RESPONSIBLE FOR THIS CHANGE SHOULD ALSO KEEP
TEMPERATURES TO NEAR SEASONAL LEVELS...THOUGH THIS WILL BE A LOT
COOLER THAN THE RECORD SMASHING TEMPERATURES WE WERE GETTING AT THE
SAME TIME LAST YEAR. NOT TIME FOR GOLF...YET.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
328 AM CST WED MAR 6 2013
.SHORT TERM...TO0DAY THROUGH FRIDAY
328 AM CST WED MAR 6 2013
FORECAST CONCERNS ARE ON FOG/FREEZING FOG POTENTIAL TONIGHT INTO
THURSDAY MORNING AND TEMPERATURES THROUGH FRIDAY. FOCUS THEN QUICKLY
TURNS TO PRECIPITATION TYPE CONCERNS THIS WEEKEND AND THE POTENTIAL
FOR MODERATE TO HEAVY RAINFALL ACROSS PARTS OF THE AREA.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED LOW
PRESSURE OVER THE CENTRAL APPALACHIANS. A TROUGH WAS NOTED ALONG
THE MINNESOTA/ONTARIO BORDER. AN UPPER RIDGE WAS BUILDING ACROSS
THE WESTERN CONUS WITH A TROUGH MOVING ONTO THE WEST COAST. SURFACE
OBSERVATIONS INDICATED A RIDGE OF HIGH PRESSURE EXTENDING FROM THE
THE DAKOTAS SOUTH THROUGH THE SOUTHERN PLAINS. A SURFACE LOW WAS
NOTED OVER VIRGINIA WITH AN INVERTED TROUGH EXTENDING NORTHWEST
INTO FAR SOUTHEAST WISCONSIN.
THE TROUGH ALONG THE MINNESOTA/ONTARIO BORDER WILL PROGRESS EAST
TODAY ACROSS LAKE SUPERIOR AS THE SURFACE RIDGE EDGES EAST INTO
THE UPPER MISSISSIPPI RIVER VALLEY. THE MAIN FORECAST CHALLENGE
TODAY WILL BE CLOUD COVER. THERE ARE CURRENTLY PLENTY OF HOLES IN
THE STRATUS LAYER OVER EASTERN MINNESOTA INTO SOUTHWEST WISCONSIN.
FORECAST SOUNDINGS SHOW LOW LEVEL CLOUDS LINGERING THROUGH THE
MORNING HOURS BEFORE FINALLY CLEARING LATE THIS AFTERNOON. THE
FORECAST MODELS HAVE BEEN STRUGGLING WITH DEWPOINTS LATELY SO NOT
SOLD ON THE CLOUDS HOLDING ON AS LONG AS THE MODELS SUGGEST.
DECIDED TO GO WITH HIGHER CLOUD COVER THIS MORNING OVER THE
PREVIOUS FORECAST...WITH CLEARING OCCURRING FROM WEST TO EAST
DURING THE MID TO LATE AFTERNOON HOURS. THE NEXT CONCERN IS THE
POTENTIAL FOR FOG/FREEZING FOG TONIGHT. FOG WOULD BE MORE
FAVORABLE IF THE CLOUDS HOLD ON TODAY. SREF GUIDANCE AND FORECAST
SOUNDINGS CONTINUE TO SUGGEST FOG DEVELOPMENT TONIGHT. LOOKING
BACK TO THE WEST...UNDER THE SURFACE RIDGE...FOG HAS DEVELOPED.
THE SREF PROBABILITIES ARE CAPTURING THIS SO FEEL THEY ARE DOING A
DECENT JOB ON CAPTURING THE FOG. WILL MAINTAIN AREAS OF FOG IN THE
FORECAST OVERNIGHT INTO THURSDAY MORNING. VISIBILITIES COULD BE
REDUCED TO LESS THAN 1/2 MILE. ALSO...THE FOG COULD FREEZE TO
OBJECTS CREATING HOAR FROST. SOME LIGHT ICING MAY OCCUR ON AREA
ROADS...BUT THE RECENTLY APPLIED TREATMENT ON THE ROADS COULD
REALLY LIMIT ICING POTENTIAL. PLAN ON LOWS FALLING INTO THE SINGLE
DIGITS TONIGHT. FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH
CENTRAL WISCONSIN WILL SEE TEMPERATURES FALL INTO THE SINGLE DIGITS
BELOW ZERO.
HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY
PROVIDING QUIET WEATHER. LOOK FOR MOSTLY SUNNY SKIES ON THURSDAY
WITH HIGHS IN THE UPPER 20S TO LOWER 30S. SURFACE HIGH PRESSURE IS
EXPECTED TO SLIDE EAST OF THE AREA ON FRIDAY AS A POTENT TROUGH
DIVES INTO THE SOUTHWEST CONUS. MEANWHILE LOW PRESSURE DEVELOPS
OVER EASTERN COLORADO AS A WARM FRONT LIFTS NORTH OUT OF THE
CENTRAL PLAINS. TWO MAIN FEATURES TO WATCH CLOSELY ON FRIDAY...A
NORTHERN STREAM TROUGH DIVING SOUTH OUT OF CENTRAL SASKATCHEWAN
AND THE SOUTHWEST LOW LIFTING NORTHEAST TOWARD THE REGION. THE
WARM FRONT LOOKS TO LIFT NORTH INTO SOUTHERN MINNESOTA/SOUTHERN
WISCONSIN FRIDAY NIGHT INTO SATURDAY MORNING THEN LIFTING NORTH
THROUGH THE DAY ON SATURDAY. THE NORTHERN STREAM WAVE AND ENERGY
EJECTING OUT OF THE SOUTHWEST WILL INTERACT WITH THE FRONT
BRINGING PRECIPITATION TO THE AREA. WARM AIR ALOFT WILL SURGE INTO
THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT LEADING TO A MIX
OF PRECIPITATION TYPES. A MIX OF FREEZING RAIN...SLEET AND SNOW IS
EXPECTED FRIDAY EVENING INTO EARLY SATURDAY MORNING SWITCHING OVER
TO MAINLY RAIN DURING THE DAY ON SATURDAY. SOME ICE ACCUMULATION
IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A MOISTURE RICH
AIRMASS MOVES INTO THE AREA DURING THE DAY ON SATURDAY WITH
PRECIPITABLE WATER VALUES APPROACHING 270 PERCENT OF NORMAL.
ALSO...TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO
LOWER 40S. 925/850 MB MOISTURE TRANSPORT FOCUSES INTO SOUTHERN
WISCONSIN AND FAR NORTHEAST IOWA SATURDAY INTO SATURDAY NIGHT.
PERIODS OF MODERATE TO HEAVY RAINFALL LOOK POSSIBLE SATURDAY INTO
SATURDAY NIGHT LEADING TO LOCALIZED FLOODING AND ICE JAMS ON AREA
RIVERS. FORECAST MODELS ARE JUST STARTING TO COME INTO AGREEMENT
ON THIS WARMER AND WET SOLUTION SO WILL HAVE TO KEEP A CLOSE WATCH
ON THE NEXT FEW RUNS.
.LONG TERM...SATURDAY THROUGH TUESDAY
328 AM CST WED MAR 6 2013
06.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY INTO
SATURDAY NIGHT BUT THEN START TO DIVERGE SUNDAY INTO EARLY MONDAY.
THE ECMWF SHIFTS THE BOUNDARY SOUTHEAST AND EAST OF THE AREA AS AN
UPPER LOW WRAPS UP OVER THE OHIO RIVER VALLEY. THE GFS LEANS TOWARD
THIS SOLUTION BUT IT IS FASTER THAN THE ECMWF...TAKING THE LOW
NORTH INTO THE EASTERN GREAT LAKES EARLY ON MONDAY. THE GEM OFFERS
A DIFFERENT SOLUTION WITH THE LOW TAKING SHAPE OVER NORTHERN
ILLINOIS WHICH WOULD BRING SIGNIFICANT SNOWFALL TO NORTHERN
WISCONSIN THROUGH SOUTHERN/CENTRAL MINNESOTA. HAVE LEANED TOWARD A
MODEL CONSENSUS BLEND APPROACH MONDAY INTO TUESDAY WITH CHANCES
FOR SNOW MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE AREA. SNOW
CHANCES WILL CONTINUE ACROSS NORTH CENTRAL WISCONSIN ON TUESDAY AS
SHORTWAVE MOVES ACROSS NORTHERN WISCONSIN. PLAN ON TEMPERATURES
COOLING SLIGHTLY EARLY NEXT WEEK WITH HIGHS FALLING INTO THE 30S
AND LOWS IN THE TEENS TO LOWER 20S.
&&
.AVIATION...THROUGH 06Z THURSDAY
1134 PM CST TUE MAR 5 2013
ALL OF THE SNOW HAS MOVED SOUTH OF THE TAF SITES WITH VFR
VISIBILITIES NOW PREVAILING. CEILING HEIGHTS HAVE BEEN ALL OVER
THE PLACE AS THE SURFACE TROUGH HAS WEAKENED BUT THE AREA STILL
REMAINS IN A LOW LEVEL CYCLONIC FLOW. THIS HAS ALLOWED POCKETS OF
VFR CEILING HEIGHTS OR EVEN CLEAR SKIES TO DEVELOP. THESE LAST FOR
A COUPLE OF HOURS BEFORE RETURNING TO MVFR. MEANWHILE...KRST SITS
IN AN IFR DECK AND IS THE ONLY SITE REPORTING ONE. SATELLITE SHOWS
THE CLOUDS EXTENDING WELL TO THE WEST UNTIL REACHING THE RIDGE
AXIS ACROSS THE DAKOTAS. MOST OF THE CEILINGS IN THIS CLOUD DECK
ARE MVFR SO WILL GO WITH THIS FOR THE MOST PART. THE 06.00Z NAM
CONTINUES TO KEEP THE LOW LEVEL RELATIVE HUMIDITY HIGH THROUGH
WEDNESDAY UNTIL THE RIDGE AXIS MOVES OVERHEAD DURING THE LATE
AFTERNOON OR EVENING. BASED ON THIS AND THE SATELLITE
TRENDS...WILL HOLD ONTO THE CLOUDS THROUGH WEDNESDAY AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
328 AM CST WED MAR 6 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
408 AM MST WED MAR 6 2013
.SHORT TERM...SWLY FLOW ALOFT WILL DEVELOP OVER THE AREA AS THE
UPPER LEVEL RIDGE SHIFTS EAST. SOME HIGHER LEVEL CLOUDS WILL BE
POSSIBLE OTHERWISE IT WILL REMAIN DRY THRU TONIGHT. ONCE AGAIN
HIGH TEMPS THIS AFTN WILL BE THE MAIN ISSUE. SOME DEEPER SNOW
COVER STILL RESIDES OVER SRN WELD...CNTRL AND ERN PORTIONS OF ADAMS
AND ARAPAHOE ALONG WITH ELBERT COUNTIES WHICH WILL AFFECT AFTN
HIGHS IN THESE AREAS AS READINGS MAY NOT GET OUT OF THE 40S.
MEANWHILE NR THE FOOTHILLS LIGHT WLY DOWNSLOPE FLOW WILL DVLP
WHICH MAY ALLOW FOR HIGHS TO REACH THE LOWER 60S OVER THE WRN AND
SRN SUBURBS OF DENVER. THUS WILL SEE QUITE A TEMP DIFFERENCE ALONG
THE FRONT RANGE THIS AFTN. OVER THE PLAINS WHERE NO SNOW COVER
EXISTS WINDS WILL BE MAINLY SELY SO WILL KEEP AFTN HIGHS IN THE
LOWER TO MID 50S EXCEPT OVER SRN LINCOLN COUNTY WHERE LOWER 60S
WILL BE POSSIBLE DUE TO SWLY LOW LVL WINDS. FOR TONIGHT MAY SEE
SOME PATCHY FOG DVLP OVER THE FAR NERN PLAINS AFTER MIDNIGHT.
.LONG TERM...THURSDAY WILL BE DRY AND WARM AS SOUTHWESTERLY FLOW
ALOFT COVERS THE STATE. FRIDAY WILL BE A TRANSITIONAL DAY AS
SOUTHWEST FLOW ALOFT CONTINUES BUT MOISTURE BEGINS INCREASING
AHEAD OF A POTENT UPPER LOW MOVING OVER THE DESERT SOUTHWEST. AND
SATURDAY LOOKS LIKE IT WILL BE THE MOST CRITICAL DAY OF THIS
FORECAST PACKAGE. EACH OF THE SYNOPTIC MODELS SHOW THE STRONG
UPPER LEVEL LOW PRESSURE SYSTEM MOVING ACROSS OR NEAR THE FOUR
CORNERS AREA ON SATURDAY...SETTING UP A SNOW PATTERN FOR NORTHEAST
COLORADO. HOWEVER...AGREEMENT BETWEEN THE MODELS IS FAR FROM
UNANIMOUS. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF AND THE NAM
ONLY GOES OUT TO MIDDAY SATURDAY BUT SHOWS AGREEMENT WITH THE GFS.
PRECIPITATION AMOUNTS ALSO VARY BETWEEN THE DIFFERENT MODELS. THE
NAM SHOWS AN INITIALLY DRY SWATH OF AIR MOVING ACROSS THE EASTERN
PLAINS WITH THE EJECTING UPPER LOW...WHILE THE GFS GENERATES
COPIOUS AMOUNTS OF SNOWFALL. THE ECMWF SHOWS ONLY LIGHT TO
MODERATE SNOW AMOUNTS THROUGH SATURDAY NIGHT. NEEDLESS TO
SAY...MANY QUESTIONS STILL REMAIN ON HOW BIG THIS STORM IS GOING
TO BE. THE STORM SYSTEM...WHICH IS CURRENTLY DEVELOPING OFF THE
COAST OF OREGON IS GOING TO CONTAIN A LOT OF COLD AIR ALOFT AND
WILL ALSO ENCOUNTER A GOOD SHOT OF LOW LEVEL MOISTURE FROM THE
GULF OF MEXICO WHEN IT MOVES ACROSS COLORADO. MODEL SOUNDINGS SHOW
LAPSE RATES SATURDAY AFTERNOON WILL BE NEARLY MOIST ADIABATIC DUE
TO THE COLD TEMPERATURES ALOFT. IF THE SYSTEM TAKES ITS TIME
MOVING ACROSS COLORADO...SIMILAR TO THE ECMWF SOLUTION...THEN IT
WILL BE ABLE TO PRODUCE SNOW AMOUNTS HEAVIER THAN WHAT THE ECMWF
CONTAINS. THE TIMING OF THE GFS AND NAM SOLUTIONS MAY WELL END UP
BEING TOO FAST AS THE SYSTEM ALREADY LOOKS LIKE IT IS READY TO
CUTOFF FROM THE NORTHERN STREAM IN THE NEXT 24 TO 36 HOURS. GIVEN
ALL THE UNCERATINTY...IT IS TOO EARLY TO ISSUE ANY HIGHLIGHTS...
BUT THAT MAY CHANGE LATER TODAY OR TONIGHT. ALONG WITH THE UPPER
DYNAMICS OF THE PASSING UPPER LOW ON SATURDAY...IT LOOKS LIKE A
STRONG SURGE OF NORTHERLY SURFACE WINDS WILL DEVELOP SATURDAY
AFTERNOON ON THE BACK SIDE OF THE STORM. HAVE ADDED AREAS OF
BLOWING SNOW TO THE SATURDAY AFTERNOON AND EVENING FORECAST.
FOR SUNDAY THROUGH TUESDAY...MODELS SHOW COLORADO UNDER NORTHWEST
FLOW WITH WARMER TEMPERATURES AND DRIER CONDITIONS. TEMPERATURE
FORECASTS FOR THESE DAYS IS GOING TO BE VERY DEPENDENT ON HOW MUCH
SNOW FALLS DURING THE SATURDAY THROUGH SUNDAY PERIOD. FOR THE TIME
BEING...WILL KEEP THIS PART OF THE FORECAST VERY GENERAL.
&&
.AVIATION...VFR THRU TONIGHT. WK SFC LOW PRES WILL LIKELY REMAIN
WEST OF THE AIRPORT THRU THIS AFTN. OVERALL THE HRRR AND RAP
KEEP WINDS LIGHT SSW THRU LATE MORNING AND THEN GRADUALLY SHIFTTHEN
MORE ELY BY EARLY AFTN. THE ELY WINDS ARE FCST TO STAY IN PLACE AT
LEAST THRU 23Z BEFORE BECOMING MORE SELY BY 01Z. WINDS WILL THEN
GRADUALLY BECOME DRAINAGE BY 03Z AND CONTINUE THAT WAY OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RPK
AREA FORECAST DISCUSSION...UPDATE
NWS TAMPA BAY RUSKIN FL
545 AM EST WED MAR 6 2013
.UPDATE...
LOW LEVEL FOCUS ALONG A FAST MOVING COLD FRONT HAS RESULTED IN MORE
ORGANIZATION TO THE SHOWER ACTIVITY AS IT PROCEEDS SOUTH OF THE
TAMPA BAY AREA. THE AREA OF SHOWERS IS STILL RATHER NARROW AND
MOVING FAST...SO ANY PERIOD OF RAIN/SHOWERS WILL BE BRIEF EARLY THIS
MORNING FOR THE SOUTHERN HALF OF THE AREA. HOWEVER...HAVE RAISED
RAIN CHANCES TO LIKELY FOR THESE ZONES TO ACCOUNT FOR THE MORE SOLID
BAND NOW SEEN ON REGIONAL RADAR. THIS BAND OF SHOWERS AND THE
ASSOCIATED COLD FRONT WILL CONTINUE TO RAPIDLY PUSH SOUTH THE NEXT
COUPLE OF HOURS AND BE SOUTH OF FT MYERS...AND OUT OF THE FORECAST
AREA BY AROUND 10AM.
&&
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A FAIRLY AMPLIFIED UPPER
LEVEL PATTERN ACROSS THE CONUS EARLY THIS MORNING. LARGE LONGWAVE
RIDGING IS NOW IN PLACE ACROSS MUCH OF THE INTER-MOUNTAIN WEST AND
CENTRAL PLAINS WITH THE DOWNSTREAM FLOW DROPPING QUICKLY INTO A
SHARP TROUGH OVER THE EASTERN STATES. THIS TROUGH IS ANCHORED BY A
TIGHT/POTENT UPPER LEVEL LOW EXITING THE TN VALLEY TOWARD THE
MID-ATLANTIC COAST. THIS ENERGY AND ASSOCIATED SURFACE FEATURE WILL
BRING A SIGNIFICANT SNOWFALL TO PARTS OF THE MID-ATLANTIC THROUGH
WEDNESDAY. OUR FORECAST AREA RESIDES AT THE BASE OF THIS
TROUGH...FAR REMOVED FROM ANY SIGNIF MID/UPPER LEVEL SYNOPTIC/QG
FORCING. WV IMAGERY SHOWS A NARROW BAND OF MOISTURE DROPPING SOUTH
ACROSS THE PENINSULA FOLLOWED QUICKLY BY MARKED DRYING/SUBSIDENCE IN
THE WAKE OF THE PASSING SHORTWAVE JUST TO OUR NORTH. THIS DRYING
WILL OVERSPREAD OUR SKIES THROUGH THE DAY. THERE IS ALSO QUITE A
SURGE OF COLD AIR ABOVE THE SURFACE ASSOCIATED WITH THIS SYSTEM TO
OUR NORTH...HOWEVER THE MAIN SURGE OF THIS AIRMASS WILL BE TOWARD
THE GA/CAROLINA COAST AND PREVENT THE ARRIVAL OF ANOTHER AIRMASS
COMPARABLE TO WHAT WAS SEEN THIS PREVIOUS WEEKEND.
AT THE SURFACE...WELL DEFINED COLD FRONT IS QUICKLY DROPPING TO THE
SOUTHEAST INTO THE NORTH-CENTRAL FL PENINSULA. JUST ENOUGH MOISTURE
IN THE LOW LEVELS AND FRONTAL FOCUS THIS MORNING TO SUPPORT A NARROW
BAND OF BROKEN (MAINLY LIGHT) SHOWERS. WINDS PICK UP QUICKLY FROM
THE NW IN THE WAKE OF THE FRONT...AND IT WILL LIKELY BE FAIRLY
EVIDENT BY THIS SURGE OF WIND WHEN THE FRONT PASSES ANY GIVEN
LOCATION THROUGH THE MORNING HOURS.
&&
.SHORT TERM (TODAY THROUGH FRIDAY)...
TODAY...COLD FRONT WILL QUICKLY DROP SOUTH THROUGH AND OUT OF THE
FORECAST AREA THIS MORNING. CURRENT GRIDS SHOW THE FRONT PASSING
SOUTH OF FT. MYERS BY LATE MORNING. THERE WILL BE A CHANCE OF A
BRIEF SHOWER OR SPRINKLE AHEAD OF THIS FRONT TO THE SOUTH OF TAMPA
BAY THROUGH MID MORNING...HOWEVER ANY RAINFALL WILL NOT AMOUNT TO
MUCH. BY SUNRISE...THE FRONT LOOKS TO HAVE ALREADY PASSED TAMPA BAY
AND POINTS NORTH TAKING ANY SCATTERED SHOWERS SOUTHWARD WITH IT.
THEREFORE...FORECAST WILL SHOW SKIES CLEARING FROM NORTH TO SOUTH
THROUGH THE DAY WITH MOST OF THE REGION SEEING ABUNDANT SUNSHINE BY
EARLY AFTERNOON. EXPECTING A BREEZY/GUSTY DAY WITH NW WINDS BEHIND
THE FRONT...AND A LAKE WIND ADVISORY HAS BEEN ISSUED FOR THIS
MORNING THROUGH EARLY EVENING. THE MOST EVIDENT CAA WILL BE NORTH OF
THE I-4 CORRIDOR WHERE HIGH TEMPS WILL HOLD IN THE LOW/MID 60S.
SOUTH OF I-4 TEMPS WILL MAKE A RUN AT 70. COOLEST TEMPS WILL BE
ALONG THE COAST FROM MANATEE COUNTY NORTHWARD WITH FLOW OFF THE
RELATIVELY COOLER SHELF WATERS. THE STRONG NW WINDS WILL ALSO BRING
BUILDING SWELL/SURF FOR AREA BEACHES AND WILL RESULT IN A
MODERATE/ELEVATED RISK OF RIP CURRENTS FROM PINELLAS COUNTY
SOUTHWARD. THIS ELEVATED RISK SHOULD LINGER INTO THURSDAY MORNING
BEFORE THE SWELL AND ONSHORE WIND COMPONENT BEGINS TO DECLINE.
TONIGHT...A CHILLY MARCH NIGHT IN STORE IN THE DRY POST-FRONTAL
ENVIRONMENT. SOME OF THE STATISTICAL GUIDANCE IS SHOWING READINGS A
COUPLE OF DEGREES BELOW FREEZING FOR THE INTERIOR NATURE COAST.
HOWEVER...STATISTICAL GUIDANCE IS ALMOST ALWAYS AT LEAST SEVERAL
DEGREES TOO COLD WITH ADVECTION SCENARIOS ON THE FIRST NIGHT BEHIND
FRONTS. THERE IS NO DOUBT THAT IT WILL BE A COLD (MIDDLE/UPPER 30S
COMMON AWAY FROM THE COAST...BUT AT THIS TIME WILL KEEP TEMPERATURES
JUST ABOVE FREEZING...EVEN UP TOWARD CITRUS AND LEVY COUNTIES. ALSO
SINCE THE GRADIENT WILL STAY UP AND OVERNIGHT DEWPOINT DEPRESSIONS
ARE FORECAST TO BE 5-8 DEGREES...THE THREAT OF FROST APPEARS LOW.
EACH OF THESE FACTORS WILL NEED TO BE RE-EVALUATED DURING THE DAY.
THURSDAY/THURSDAY NIGHT...
A BROAD DEEP LAYER NORTHWEST FLOW WILL BE IN PLACE ON THE BACKSIDE
OF LONGWAVE TROUGHING OFF THE ATLANTIC SEABOARD. THIS FLOW WILL KEEP
A STEADY SUPPLY OF DRY AIR ARRIVING FROM THE NORTH. MAY SEE A BOUT
OF HIGHER CIRRUS LATER THURSDAY/THURSDAY EVENING OVER THE NORTHERN
HALF OF THE STATE ASSOCIATED WITH A WEAK PASSING SHORTWAVE...BUT
OTHERWISE SKIES LOOK TO BE MOSTLY CLEAR. WINDS WILL BE LESS GUSTY
FOR THURSDAY AS SURFACE RIDGING CONTINUES TO BUILD IN FROM THE
NORTHWEST. HIGH TEMPS WILL GENERALLY REACH THE UPPER 60S TO NEAR 70
NORTH AND THE LOWER/MID 70S SOUTH. BEACH TEMPS WILL LIKELY AGAIN BE
HELD IN THE 60S WITH AT LEAST SOME ONSHORE FLOW COMPONENT...
ESPECIALLY NORTH OF LEE/CHARLOTTE COUNTIES. WIDESPREAD 40S THURSDAY
NIGHT FOR LOW TEMPS...WITH SOME UPPER 30S FOR THE NATURE COAST.
FRIDAY...
"CHAMBER OF COMMERCE" WEATHER TO END THE WORK WEEK AFTER A COOL
EARLY MORNING START. STACKED RIDGING WILL BE BUILDING EASTWARD
ACROSS THE GULF TOWARD THE AREA CONTINUING A FORECAST OF ABUNDANT
SUNSHINE AND WARMING TEMPERATURES.
&&
.LONG TERM (FRIDAY NIGHT THROUGH NEXT TUESDAY)...
THE PERIOD BEGINS WITH DEEP LAYER RIDGING FROM THE GULF TO THE
GREAT LAKES. THROUGH THE WEEKEND THIS RIDGING SLOWLY SHIFTS EAST
ACROSS THE AREA WITH DRY AND SEASONABLE CONDITIONS AS WINDS VEER
FROM NORTH TO SOUTHEAST AND MAY BE ROBUST AT TIMES ON THE GULF.
BY MON THE RIDGING WILL BE EAST OF FL AS AN UPPER LOW/TROUGH
WITH AN ATTENDANT SURFACE FRONT MOVES INTO THE MID CONUS. THIS
SYSTEM CONTINUES EAST TUE...PUSHING THE FRONT DOWN THE STATE WITH
INCREASING CLOUDS AND A SLIGHT CHANCE OF SHOWERS SPREADING
SOUTHWARD. THE LATEST GFS AND ECMWF GUIDANCE WERE FAIRLY CONSISTENT
THROUGH THE PERIOD BUT BEGIN TO DIVERGE TUE WITH THE ECMWF SLOWER
THAN THE GFS IN MOVING THE FRONT ACROSS FL.
&&
.AVIATION...
APPROACHING FRONT WILL SPREAD SHRA/VCSH UNDER BKN MVFR CIGS
SOUTHWARD...BEGINNING AT 09Z IN THE NORTH AND ENDING AROUND 18Z IN
THE SOUTH. SOUTH AND SW WINDS SHIFT TO NW AND GUSTY FOR THE LATE
MORNING AND AFTERNOON.
&&
.MARINE...
A COLD FRONT WILL QUICKLY PASS SOUTH THROUGH THE EASTERN GULF OF
MEXICO THIS MORNING. WINDS FROM THE NORTHWEST AND SEAS WILL RAPIDLY
INCREASE TO ADVISORY LEVELS BEHIND THE FRONT AND LINGER THROUGH THE
DAY AND EVENING. LATER TONIGHT...WINDS AND SEAS WILL BEGIN TO
SUBSIDE. WINDS AND SEAS WILL GENERALLY REMAIN BELOW HEADLINE
CRITERIA FROM THURSDAY AFTERNOON THROUGH THE DAYLIGHT HOURS FRIDAY
AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THIS RIDGE SLIDES
EASTWARD FOR THE UPCOMING WEEKEND SETTING UP A GOOD SCENARIO FOR
NOCTURNAL AND EARLY MORNING EASTERLY WIND SURGES. THESE SURGES ARE
CURRENTLY FORECAST TO REACH CAUTIONARY LEVELS BOTH FRIDAY NIGHT AND
SATURDAY NIGHT.
&&
.FIRE WEATHER...
DRY AIR ARRIVING BEHIND A COLD FRONT WILL COMBINE WITH GUSTY NW
WINDS AND ERC VALUES ABOVE 27 TO RESULT IN RED FLAG CONDITIONS FOR
MOST OF THE REGION THIS AFTERNOON. THE ONLY EXCEPTIONS WILL BE NEAR
THE COAST WHERE ONSHORE FLOW SHOULD HELP PREVENT CRITICAL RELATIVE
HUMIDITY LEVELS. SEVERAL HOURS OF CRITICALLY LOW RELATIVE HUMIDITY
APPEAR LIKELY FOR THURSDAY LATE MORNING/AFTERNOON AS WELL.
HOWEVER...LIGHTER WINDS AND CURRENT ERC VALUES BELOW 37 DO NOT
MATCH RED FLAG CRITERIA FOR ANY ZONES. THIS POTENTIAL FOR RED FLAG
CONDITIONS CAN BE RE-EVALUATED THIS AFTERNOON WITH THE ISSUANCE OF
THE NEW ERC VALUES. IF ANY ZONES RISE TO 37 OR HIGHER...WARNINGS
WILL LIKELY BECOME REQUIRED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 64 43 67 47 / 10 0 0 0
FMY 72 44 71 48 / 30 0 0 0
GIF 68 40 72 44 / 10 0 0 0
SRQ 65 44 67 46 / 20 0 0 0
BKV 64 36 68 38 / 10 0 0 0
SPG 63 49 67 53 / 10 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST
THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-
HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE-
PASCO-PINELLAS-POLK-SARASOTA-SUMTER.
RED FLAG WARNING FROM NOON TODAY TO 7 PM EST THIS EVENING
FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS-
HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-POLK-SARASOTA-
SUMTER.
BEACH HAZARDS STATEMENT THROUGH THURSDAY MORNING FOR
CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR TARPON
SPRINGS TO SUWANNEE RIVER OUT 20 NM-TARPON SPRINGS TO
SUWANNEE RIVER OUT 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR BONITA
BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-
TAMPA BAY WATERS.
&&
$$
UPDATE/SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1006 AM EST WED MAR 6 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 350 AM EST WED MAR 6 2013
STRONG LOW PRESSURE OVER SOUTHEAST OHIO WILL MOVE ON TO THE EAST
COAST AS UPPER DISTURBANCE MOVES SOUTHEAST ACROSS THE GREAT LAKES.
OVER THE NEXT FEW DAYS MODELS MOVE AN AREA OF HIGH PRESSURE EAST
INTO OUR REGION AND AN UPPER RIDGE OF HIGH PRESSURE OVER THE ROCKIES
WILL MOVE OUR WAY BY SATURDAY.
IN THE EXTENDED..AN AREA OF LOW PRESSURE WILL MOVE OUR WAY LATE
SUNDAY AND MONDAY. TEMPERATURES WILL BE QUITE MILD THIS
WEEKEND...BUT WILL COOL OFF SOME MONDAY AND TUESDAY AFTER A COLD
FRONT MOVES THROUGH.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1006 AM EST WED MAR 6 2013
RADAR LOOP SHOWED SNOW SHOWERS HAD MOVED OUT OF THE AREA EARLIER
THIS MORNING SO WINTER WEATHER ADVISORY WAS ALLOWED TO EXPIRE AT 9
AM. SATELLITE PICTURE SHOWS CLOUDY SKIES ACROSS ALL OF CENTRAL
INDIANA AND THIS TREND SHOULD CONTINUE THROUGH THE DAY...WITH
PERHAPS MOSTLY CLOUDY BY LATE THIS EVENING. WING GUSTS OF 20 TO 30
MPH CONTINUE ACROSS THE AREA BUT SHOULD LESSEN GRADUALLY
THROUGHOUT THE DAY. FORECAST SOUNDINGS IN BOTH THE NAM AND THE RAP FOR
THIS AFTERNOON SHOW SOME SHALLOW INSTABILITY AND RECENTLY THIS HAS
BEEN A PRETTY GOOD INDICATOR OF LIGHT SNOW SHOWER DEVELOPMENT.
WITH LITTLE IN THE WAY OF FORCING ON THE BACK SIDE OF THIS LOW HAVE
OPTED AGAINST ADDING ANYTHING MEASURABLE BUT HAVE ADDED A CHANCE
FOR FLURRIES FOR THE AFTERNOON. GOING HIGH TEMPERATURES IN THE 30S
LOOK GOOD WITH THE CLOUD COVER AND NORTHWEST FLOW.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 350 AM EST WED MAR 6 2013
FORECAST FOCUS WILL BE ON SKY COVER AND TEMPERATURES AS MUCH QUIETER
WEATHER WILL BE THE RULE. HIGH PRESSURE RIDGE DRIFTS ACROSS THE
PLAINS WILL BUILD EAST ACROSS OUR REGION FRIDAY. WITH
SUBSIDENCE...CLOUDS WILL GRADUALLY DECREASE LATER TONIGHT AND
THURSDAY. MODELS MOVE AN UPPER DISTURBANCE ACROSS SOUTHEAST ACROSS
THE EASTERN GREAT LAKES AND EASTERN OHIO LATER TONIGHT AND THURSDAY.
WILL KEEP MORE CLOUDS ACROSS OUR NORTH AND EAST THROUGH THURSDAY.
OTHERWISE...MOST AREAS WILL BECOME MOSTLY CLEAR THURSDAY NIGHT AND
REMAIN THAT WAY UNTIL SATURDAY MORNING.
WILL LEAN TOWARDS THE COOLER END OF MOS TEMPERATURES THROUGH
THURSDAY NIGHT AS THERE WILL BE SOME SNOW COVER ESPECIALLY EAST.
WITH CLEAR SKIES AND LIGHT WINDS WILL UNDERCUT MOS TEMPERATURES 4 TO
6 DEGREES THURSDAY NIGHT. BY FRIDAY THE SNOW COVER SHOULD BE MOSTLY
GONE AND WILL WITH THE POSSIBLE EXCEPTION OUR FAR EAST. WILL GO
CLOSE TO A MOS BLEND ON TEMPERATURES.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 336 PM EST TUE MAR 5 2013
AN UPPER RIDGE WILL BUILD OVER THE REGION LATE IN THE WORK WEEK AND
MOVES EAST CROSS THE REGION THROUGH THE WEEKEND. DRY WEATHER AND
WARMER TEMPERATURES WILL ENSUE ACROSS THE AREA. BY SUNDAY A BROAD
UPPER TROUGH WILL APPROACH THE REGION. A DISTURBANCE OUT OF AHEAD OF
THIS SYSTEM WILL MOVE ACROSS THE AREA SUNDAY...WITH THE STRONG UPPER
LOW TO CROSS THE REGION MONDAY AND TUESDAY. SLIGHT CHANCE FOR RAIN
WILL BE IN THE FORECAST FOR SUNDAY WITH HIGHER CHANCES FROM MONDAY
INTO TUESDAY AS THE CENTER OF THE UPPER LOW MOVES ACROSS THE GREAT
LAKES. ALL BLEND TEMPERATURES SEEM REASONABLE GIVEN MODEL CONSENSUS
AND DID NOT MAKE ANY SIGNIFICANT CHANGES TO THEIR NUMBERS.
&&
.AVIATION /DISCUSSION FOR THE 061500Z TAF UPDATE/...
ISSUED AT 947 AM EST WED MAR 6 2013
THICK MVFR STRATUS REMAINS ACROSS THE REGION THIS MORNING. MADE SOME
MINOR ADJUSTMENTS TO CEILINGS BASED ON CURRENT OBS BUT IN
GENERAL...12Z FORECAST LOOKS GOOD. GUSTS LIKELY TO CONTINUE AT
KBMG...KIND AND POSSIBLY KHUF THROUGH THE REMAINDER OF THE MORNING.
CANNOT RULE OUT A FEW FLURRIES INTO THE AFTERNOON...BUT ANY IMPACT
TO TERMINALS WILL BE MINIMAL AT BEST AND WILL NOT INTRODUCE INTO
FORECASTS AT THIS TIME.
12Z DISCUSSION FOLLOWS.
MVFR CONDITIONS LIKELY THROUGH THE PERIOD IN THE WAKE OF DEPARTING
LOW PRESSURE.
SAVE FOR HUF...ALL SITES ARE NOW MVFR AND SNOW IS RAPIDLY COMING TO
AN END...ASIDE FROM A FEW FLURRIES REMAINING.
APPEARS LIKELY THAT MOISTURE WILL REMAIN TRAPPED UNDER A LOW LEVEL
INVERSION THROUGH MUCH OF THE PERIOD...AND UPSTREAM OBSERVATIONS AND
SATELLITE BEAR THIS OUT...SHOWING EXPANSIVE LOW CLOUD TO OUR WEST
AND NORTHWEST.
WINDS WILL GENERALLY REMAIN NORTHWESTERLY...WITH SOME GUSTS LIKELY
EARLY IN THE PERIOD BEFORE THE SURFACE PRESSURE GRADIENT RELAXES.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...CP
SHORT TERM...JH
LONG TERM....NIELD
AVIATION...NIELD/RYAN
AREA FORECAST DISCUSSION
NWS DES MOINES IA
547 AM CST WED MAR 6 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY /...
MAIN FORECAST CONCERN TODAY IS LINGERING
STRATUS DECK AND WHETHER IT WILL DISSIPATE DURING THE AFTERNOON.
SURFACE HIGH AND UPPER LEVEL RIDGE BUILD INTO THE STATE PAST 18Z
TODAY AND BRING LIGHT FLOW TO THE FORECAST AREA. INVERSION
STRENGTHENS AS DRIER AIR FILTER WITH THE UPPER RIDGE MOVING INTO THE
STATE THIS AFTERNOON. STRATUS DECK EXTENDS UP INTO CANADA AND THE
GENERALLY NORTH FLOW CONTINUES THROUGH AT LEAST MIDDAY BEFORE WINDS
BECOME LIGHT AND VARIABLE. LOW CONFIDENCE WITH STRATUS DISSIPATING
BEFORE 18Z AND EVEN AT ALL THROUGH THE AFTERNOON. VERY MINIMAL
MIXING AND IF STRATUS DECK REMAINS IN PLACE WHEN SURFACE HIGH SLIDES
OVER CENTRAL IOWA...THINKING IT WILL BECOME TRAPPED UNDERNEATH THE
INVERSION INTO THIS EVENING OR POSSIBLY TOMORROW BEFORE THE WAA
DEVELOPS ON THE BACKSIDE OF THE SURFACE HIGH. AS A
RESULT...INCREASED SKY COVER THROUGH THE AFTERNOON WITH IT SLOWLY
DISSIPATING PAST 21Z. THE 05Z HRRR KEEPS THE STRATUS GOING THROUGH
THE AFTERNOON EXCEPT THE FAR SOUTHWEST. WRT TO TEMPS TODAY...LEANED
TOWARD THE NAM FOR MAX TEMPS TODAY AS IT SEEMS TO HAVE A GOOD HANDLE
ON THE STRATUS AS WELL.
.LONG TERM /TONIGHT THROUGH TUESDAY/...
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS IOWA TONIGHT. STILL
UNCERTAIN HOW WIDESPREAD THE STRATUS WILL BE OVERNIGHT. THE
STRATUS WILL BE TOUGH TO GET RID OF OVERNIGHT IF IT SURVIVES TODAY
WITH VERY LITTLE SUBSIDENCE OR STEERING FLOW IN PLACE. THE
UNCERTAINTY WITH THE STRATUS LEAVES A WIDE RANGE IN POSSIBLE LOW
TEMPERATURES OVERNIGHT. TEMPERATURES WILL DROP WELL INTO THE
SINGLE DIGITS OVERNIGHT ACROSS THE NORTHEAST WITH CLEARING BUT
WOULD REMAIN IN THE MID TO UPPER TEENS IF CLOUDS PERSIST. HAVE
LEANED TOWARDS CLEARING OR PARTIAL CLEARING AND COLDER
TEMPERATURES AT THIS TIME. THE HIGH PRESSURE RIDGE SHIFTS EAST ON
THURSDAY WITH RETURN FLOW DEVELOPING IN ADDITION TO A TRANSITION
TO MID LEVEL RIDGING. THIS WILL CONTINUE INTO FRIDAY WITH EVEN
WARMER TEMPERATURES EXPECTED IN THE UPPER 30S TO UPPER 40S.
A POTENT UPPER LEVEL SYSTEM CONSISTING OF SEVERAL STRONG SHORT
WAVES ROTATING AROUND THE CORE WILL BEGIN TO MOVE OVER CALIFORNIA
ON FRIDAY. ANOTHER SHORT WAVE UNDERCUTTING THE SYSTEM WILL PUSH
OUT AHEAD AND ARRIVE OVER NEBRASKA AND IOWA BY FRIDAY NIGHT. AN
INCREASING LOW LEVEL JET AND ASSOCIATED STRONG THETA-E ADVECTION
ALONG WITH THE QG FORCING FROM THE UPPER WAVE WILL HELP SHOWERS
AND A FEW THUNDERSTORMS DEVELOP ACROSS MAINLY CENTRAL AND WESTERN
IOWA. OVERNIGHT LOW TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE
FREEZING WITH LOW LEVEL MOISTURE SURGE BRINGING DEWPOINTS IN THE
3OS TO THE AREA. THE FORECAST AREA WILL BE IN THE WARM SECTOR
THROUGH THE DAY SATURDAY. THE PRIMARY UPPER LEVEL SYSTEM WILL LIFT
INTO THE MIDWEST SATURDAY NIGHT INTO SUNDAY. THE ECMWF IS A BIT
FASTER WITH THE SFC FEATURES WITH THE COLD FRONT DROPPING THROUGH
MUCH OF CENTRAL IOWA BY 12Z SUNDAY WHILE THE GFS IS A BIT SLOWER.
ANY PRECIPITATION WILL SWITCH OVER TO SNOW BEHIND THE COLD FRONT
AS PROFILES COOL. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE. COLD
ADVECTION WILL BE PROMINENT MUCH OF THE DAY SUNDAY WITH HIGH
TEMPERATURES EARLY IN THE DAY. 850 MB TEMPERATURES BY 12Z MONDAY
WILL BE -8C TO -10C ACROSS MUCH OF THE AREA AND HAVE CONTINUED THE
COOLING TREND INTO MONDAY. SOME MODERATION FOR THE END OF THE
PERIOD WITH LOW CHANCES FOR PRECIPITATION.
&&
.AVIATION...
MVFR STRATUS WILL CONTINUE THROUGH MUCH OF THE DAY AND POSSIBLY
INTO TONIGHT. CONFIDENCE IS GROWING WITH THIS STRATUS PERSISTING
INTO THURSDAY MORNING AS HIRES MODELS KEEP IT THROUGH LATE THIS
AFTERNOON AND WITH THE HIGH BUILDING INTO THE STATE...EXPECTING
INVERSION TO HOLD IT IN PLACE THROUGH TONIGHT. MOS GUIDANCE
REDEVELOPS MVFR STRATUS BY 03Z THURSDAY. HAVE BRIEF BREAK IN THE
MVFR CIGS THIS AFTERNOON...BUT BRING IT BACK IN LATE TONIGHT INTO
THE OVERNIGHT HOURS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1034 AM EST WED MAR 6 2013
.SYNOPSIS...
SNOW WILL DIMINISH AS LOW PRESSURE CONTINUES MOVING EASTWARD.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE BAND OF SNOW ASSOCIATED WITH THE DEFORMATION ZONE CONTINUES TO
DIMINISH AS IT SHIFTS TO THE SOUTH OVER SW PA THIS MORNING.
THUS...HAVE CANCELLED THE ADVISORY FOR BUTLER AND ARMSTRONG
COUNTIES. THE HRRR SEEMS TO BE HANDLING THIS BAND WELL SO HAVE
ADJUSTED POPS ACCORDINGLY BASED OFF OF CURRENT RADAR AND HRRR
MODEL TRENDS. WITH DEFORMATION SNOWS LASTING LONGEST OVER THE
RIDGES...THINK THEY WILL EASILY SEE ANOTHER 2-5 INCHES OF SNOW AND
WILL KEEP THE WARNING GOING FOR NOW. OTHERWISE...ONLY SMALL
ADJUSTMENTS WERE NEEDED TO TEMPS...DEWPOINTS...AND WINDS THROUGH
THE AFTERNOON.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
STILL TRYING TO GET A GOOD HANDLE OF SNOW POSSIBILITIES FOR
THURSDAY INTO THURSDAY NIGHT. MODELS ARE NOW SHOWING A WEAK UPPER
LEVEL WAVE DROPPING ACROSS ONTARIO...WITH THE BEST MOISTURE AND
DYNAMICS EXPECTED TO CROSS NEW YORK AND CENTRAL/EASTERN
PENNSYLVANIA. HAVE ADDED A SLIGHT CHANCE OF PRECIPITATION INTO THE
FORECAST NORTH AND EAST OF PITTSBURGH. WIND DIRECTIONS WILL BE
CRITICAL TO WHETHER ANY FLAKES ARE SEEN IN THE UPSLOPE REGIONS OF
PA/WV/MD. CURRENTLY HAVE A NORTHWEST WIND WHICH WOULD ALLOW FOR
SOME VERY LIGHT UPSLOPE SNOW...BUT IF WIND DIRECTIONS ARE MORE
NORTHERLY SUCH AS SHOWN IN THE NAM...WOULD NOT EXPECT TO SEE ANY
SNOW TO THE SOUTH. HIGH PRESSURE WILL THEN BUILD IN FOR THURSDAY
NIGHT AND FRIDAY...BRINGING DRY CONDITIONS TO ALL LOCATIONS.
TEMPERATURES WILL RISE A FEW DEGREES FROM WEDNESDAY READINGS...BUT
STILL REMAIN A COUPLE OF DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MODELS ARE IN GOOD AGREEMENT WITH DEPICTIONS OF SATURDAY WEATHER...BUT
DIVERGENT SOLNS QUICKLY ERODE LONG TERM FORECAST CONFIDENCE. FAIRLY
BROAD AND AMPLIFIED ERN CONUS RIDGE IS EXPECTED TO BE BROKEN
DOWN DURING THE PD...ALBEIT WITH QNABLE TIMING.
PERSISTENCE/COLLABORATED LONG TERM PROGNOSIS THUS FEATURES TEMPS
AT...OR ABOVE THE SEASONAL AVERAGES ACCOMPANIED BY GRADUALLY
INCRSG PCPN PROBABILITIES TO NR CLIMO NMBRS THRU EARLY NXT WEEK.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AREA OF LINGERING SN BTN PIT...LBE AND MGW WL GRADUALLY DIMINISH BY
THIS AFTN. VFR CONDITIONS MAY BRIEFLY RTN AS SBSDNC INCRS IN THE
WAKE OF THE EXITING LOW...BUT MORE RESTRICTION IN STRATOCU...AND
POSSIBLY SOME FOG ARE ANTICIPATED OVRNGT AND INTO EARLY THURSDAY.
.OUTLOOK.../THURSDAY THROUGH SATURDAY/...
GENL VFR CONDITIONS ARE ANTICIPATED FOR THE END OF THE WEEK AS HIGH
PRES BLDS OVR THE REGION.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MDZ001.
OH...NONE.
PA...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR PAZ021-
029-031-073-075.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR PAZ074-
076.
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
PAZ023.
WV...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR WVZ021-
022.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ023-
041.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
942 AM EST WED MAR 6 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW
WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD
OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
STACKED LOW PRESSURE OVER THE HAMPTONS WILL SLOWLY PUSH
OFFSHORE THROUGH THIS AFTERNOON. WINDS HAVE SHIFTED TO THE NNE
OVER THE I95 CORRIDOR...AND PRECIPITATION HAS CHANGED OVER TO
HEAVY SNOW. AREAS TO THE SOUTHEAST OF BALTIMORE/DC SHOULD CHANGE
OVER TO SNOW AS WELL OVER THE NEXT SEVERAL HOURS. GIVEN THE
DURATION OF RAINFALL OVER THE REGION SO FAR THIS MORNING...HAVE
LOWERED SNOW TOTALS ALONG AND EAST OF I-95...BUT MAINTAINING
WINTER STORM WARNING FOR THE ENTIRE AREA.
ALSO ADDED ISOLATED THUNDER TO AREAS S OF THE DC METRO. CONVECTION
CURRENTLY OCCURRING OVER SE VA MAY ROTATE NWD INTO THE PIEDMONT AND
SRN MD. ONE STRIKE WAS NOTED EARLIER OVER CULPEPER COUNTY...AND
FORECAST SOUNDINGS INDICATE ELEVATED INSTABILITY.
PRECIP IS EXPECTED TO CONTINUE THROUGH THE AFTERNOON. BANDS OF
HEAVIER PRECIP EXPECTED TO ROTATE AROUND THE NORTH AND WEST SIDE
OF THE LOW...AS LIFT CONTINUES TO BE STRONG. HRRR ADVERTISES ONE
SUCH BAND ROTATING AROUND THE DC METRO AREA THROUGH LATE
AFTERNOON...AND OTHER BANDING ACTIVITY ALONG AND WEST OF THE BLUE
RIDGE WHERE SIGNIFICANT SNOWFALL HAS ALREADY FALLEN.
A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE
MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE
COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY
FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE
BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY
OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW
FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER
INTO THE EARLY MRNG HRS THU.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST
TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH
FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME.
ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION
SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY
FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE
WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE
AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH
SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE
SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS
SHOWING CLEAR TO PARTLY CLOUDY SKIES.
NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN
SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY.
CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST
SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC
HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND
CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S
WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR
I-95.
EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES
SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE.
GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL
WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS
COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
SNOW CONTINUES THROUGH TODAY. VSBYS WILL FLUCTUATE FROM MVFR TO
LIFR AS HEAVIER BANDS OF SNOW MOVE THROUGH THE TERMINALS. INTENSE
SNOWFALL RATES...GUSTY WINDS AND REDUCED VSBYS WILL BE CENTERED
OVER THE I-95 CORRIDOR AND BACK TOWARD THE BLUE RIDGE BETWEEN
THROUGH 20Z...TAPERING OFF TOWARD THE END OF THAT PERIOD. SNOW
WILL BEGIN TO DISSIPATE DURING THE EVE HRS...BUT WINDS WILL REMAIN
BREEZY OUT OF THE NW ALL NIGHT AND INTO THU.
PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN
TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY
NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH
PRESSURE THIS WEEKEND.
&&
.MARINE...
GALE FORCE WIND GUSTS CONTINUE TODAY...AS A SFC LOW SLOWLY MOVES
EWD OFF THE COAST NEAR NORFOLK. SOLID GALE GUSTS WILL STREAM DOWN THE MAIN
CHANNEL OF THE BAY AND TP RVR. THIS WILL CONTINUE INTO THE LATE
NIGHT HRS...AND WINDS WILL STILL GUST IN THE GALE RANGE OVERNIGHT.
WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT
HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA
CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK.
&&
.HYDROLOGY...
WILL BE WATCHING SNOWMELT OVER THE NEXT SEVERAL DAYS. ALREADY HAVE
NUMEROUS REPORTS OF OVER A FOOT OF SNOW. A GRADUAL MELT SEEMS MOST
LIKELY BUT WILL HAVE TO KEEP AN EYE ON IT THROUGH THE END OF THE
WEEK.
&&
.TIDES/COASTAL FLOODING...
WINDS ARE NOW OUT OF THE NORTHEAST IN THE TIDAL ZONE...BUT OUT OF
THE EAST JUST ACROSS THE EASTERN SHORE. LEWISETTA IS OVERACHIEVING
THE MODEL FORECAST...NEAR MODERATE FLOOD LEVEL. COASTAL FLOOD
ADVISORY IS STILL OUT FOR THE WESTERN SHORE EXCEPT HARFORD...AND THE
ST. MARYS PORTION OF THE TIDAL POTOMAC. NEW GUIDANCE FROM MARFC
TAKES THE UPPER POTOMAC TO MINOR FLOOD ALSO LATER TODAY. NOT SO SURE
ABOUT THAT JUST YET GIVEN THE NORTH WIND...BUT WILL MONITOR FOR THE
NEED TO ADD ANYTHING TO THE ADVISORY.
AS WINDS TURN NORTHERLY LATE TODAY...GIVEN THEIR EXPECTED
STRENGTH...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS COMPLETELY
DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER IN THE UPPER
BAY. FORECAST MODEL STILL SHOWS A LITTLE WATER TRAPPING IN THE
LOWERMOST TIDAL POTOMAC...AND WILL HAVE TO WATCH TRENDS TO SEE IF
ANOTHER ADVISORY IS NEEDED FOR ST. MARYS COUNTY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001.
MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501-
502.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007-
009>011-013-014-016>018.
COASTAL FLOOD ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
MDZ014-017-018.
COASTAL FLOOD ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
MDZ011.
VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031-
503-504.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040-
042-050>057-501-502.
WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053-
055-501>506.
MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535-
536.
GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536.
&&
$$
SYNOPSIS...BPP/GMS
NEAR TERM...GMS/KCS
SHORT TERM...BPP
LONG TERM...JRK
AVIATION...KCS/BPP/JRK
MARINE...JRK/BPP/KCS
HYDROLOGY...JE
TIDES/COASTAL FLOODING...JE
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
837 AM EST WED MAR 6 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW
WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD
OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 0830AM...QUICK UPDATE MADE TO MORNING FCST BASED ON CURRENT
RADAR/OBS. RAIN/SNOW LINE IS JUST TO SOUTHEAST OF A LINE FROM
BWI/ADW/DCA. SOUTHEAST OF THIS LINE...MOSTLY RAIN IS FALLING WITH
SURFACE TEMPS IN UPPER 30S...TO EVEN LOW 40S OVER SRN MD.
LOW PRESSURE IS NOW OVER THE NORFOLK METRO AREA...WITH AN EASTERLY
WIND ADVECTING MARINE AIR OVER SRN MD. AS THE BOTH THE SURFACE AND
UPPER LOW MOVE TOWARDS THE NORTH DURING THE DAY TODAY...WINDS ARE
EXPECTED TO BECOME MORE NORTHERLY AND DRAW IN COOLER AIR. FOR THIS
REASON...STILL EXPECTING A CHANGEOVER TO SNOW ALONG AND EAST OF
THE I-95 CORRIDOR. ADJUSTED SNOWFALL TOTALS DOWN S AND E OF
BWI/DCA BASED ON LOWER SNOW ACCUM IN THE MORNING. ALSO ADJUSTED
TOTALS ALONG AND W OF THE BLUE RIDGE BASED ON REPORTS.
ALSO ADDED ISOLATED THUNDER TO AREAS S OF THE DC METRO. CONVECTION
CURRENTLY OCCURRING OVER SE VA MAY ROTATE NWD INTO THE PIEDMONT AND
SRN MD. ONE STRIKE WAS NOTED EARLIER OVER CULPEPER COUNTY...AND
FORECAST SOUNDINGS INDICATE ELEVATED INSTABILITY.
PREVIOUS DISCUSSION....
THE TRANSITION BETWEEN PHASES OF THIS INTENSE AND IMPACTFUL
INCOMING SNOWSTORM IS FULLY UNDERWAY. THE INITIAL SFC LOW THAT
DROPPED DOWN FROM THE NRN PLAINS INTO THE UPPER MIDWEST IS ABOUT
TO BE PHASED-OUT. THE NEWER AND STRONGER LOW CURRENTLY OVER THE
RALEIGH NC AREA WILL CREATE A SNOWY AND HAZARDOUS WEDNESDAY FOR
MUCH OF THE MID-ATLC. THE NEXT SEVERAL HOURS WILL BE THE CRITICAL
TRANSITION PERIOD AS THIS LOW INTENSIFIES AND ROTATES DUE NE
TOWARD THE LOWER TIP OF THE DELMARVA PENINSULA AND DEVELOPS HEAVY
SNOW BAND ACROSS THE NWRN QUADRANT OF THE LOW DURING THE DAYTIME
HRS.
THROUGH DAYBREAK...
A REGIONAL VIEW OF THE RADAR RETURNS SHOWS THAT SNOW STILL AFFECTING
MUCH OF THE UPPER MIDWEST...FROM CNTRL IN TO THE APLCNS...BUT THIS
AREA OF PRECIP REGION WILL DISSIPATE IN THE NEXT FEW HRS. ONLY
POCKETS OF HIGHER ELEVATION UPSLOPE SNOW WILL CONTINUE ALONG THE
APLCN CHAIN.
THE FIRST PHASE OF THE SYSTEM THAT BROUGHT LIGHT TO MODERATE SNOW
OVER THE ENTIRE REGION IN JUST THE PAST FEW HOURS IS JUST THE START.
ABOUT A HALF-FOOT OF SNOW HAS ALREADY FALLEN OVER THE HIGHER TERRAIN
OF THE CNTRL APLCNS...TOWARD THE BLUE RIDGE. A FEW INCHES HAVE
BEEN COMMON OVER THE SWRN QUADRANT OF THE CWA THRU 2-3AM. THE
HEAVIER BANDS THAT BROUGHT THIS ACTIVITY ARE NOW SPREADING ACROSS
THE DC/BALT AND THE PIEDMONT AREAS. THIS ACTIVITY WILL CREATE THE
FIRST LAYER OF SNOW AND ALLOW FOR THE INITIAL BASE FOR ACCUMULATIONS
FROM THE SECOND PHASE OF THE STORM.
WINDS HAVE BEEN INTERMITTENTLY INCREASED...NORMALLY W/ SOME OF THE
HEAVIER BANDS BUT THEN DROP BACK DOWN TO 5-10MPH. THESE LOWER WIND
SPEEDS ARE ALLOWING FOR THE RELATIVELY HIGHER VISIBILITIES IN THE
1-2SM RANGE. THIS WILL CHANGE AS WINDS INCREASE AND SNOW
INTENSITIES INCREASE. DETERMINISTIC NAM AND GFS RUNS STILL BULLISH
ON QPF...SO THE CURRENT FORECAST IS A GOOD MIX OF NEAR TERM HI-RES
GUIDANCE...INCLUDING LOCAL VERSION OF THE VARIOUS WRF MEMBERS AND
ESPC THE HRRR WHICH HAS DONE WELL W/ INITIALIZING OVER THE FIRST
PART OF THIS EVENT.
DAYBREAK THROUGH MIDDAY...
IF THEY HAVEN`T ALREADY BY DAYBREAK - CONDITIONS WILL DETERIORATE
RAPIDLY ACROSS MOST - IF NOT ALL - OF THE CWA. LOCALIZED AREAS WILL
RECEIVE BRIEF INTENSE SNOWFALL RATES OF 1-2 INCHES PER HR...POSSIBLY
HIGHER. NOW THAT THE LOW IS ON THE DOORSTEP AND NEAR-TERM GUIDANCE
HAS BEEN INITIALIZING W/ THIS DATA...SOME OF THE HI-RES MEMBERS HAVE
STARTED TO DEPICT ONE LARGE ENCOMPASSING SNOW BAND - ORIENTED ALONG
THE I-95 CORRIDOR BUT STRETCHING OVER THE ENTIRETY OF THE
PIEDMONT/COASTAL COUNTIES...TAPERING OFF TOWARD THE BLUE RIDGE AND
APLCNS. WITHIN THIS LARGER BAND WILL BE THE DYNAMIC HEAVIER BANDS W/
THE HIGHER INTENSITIES AND LOW VISIBILITIES.
WINDS AROUND THIS SECTOR OF THE STORM WILL BE STRENGTHENING W/ SUST
SPEEDS IN THE 15-25MPH RANGE AND PEAK GUSTS IN THE 30-40MPH RANGE.
NEAR-WHITEOUT CONDITIONS ARE STILL IN QUESTION...IN TERMS OF AREA
AND DURATION. THERE WILL BE BRIEF PERIODS OF NEAR-WHITEOUT
CONDITIONS BUT AS FAR WIDESPREAD AND LONG-LIVED DURATIONS...
CONFIDENCE IS LOWER. REGARDLESS...THE HEAVY-WET SNOW AND GUSTY WINDS
WILL CREATE DANGEROUS AND NEAR-IMPOSSIBLE TRAVEL AT TIMES.
MIDDAY THROUGH LATE TONIGHT...
THE HEIGHT OF SNOWFALL RATES AND INTENSITIES ACROSS THE I-95
CORRIDOR...THE METRO AREAS AND THE VA/MD PIEDMONT IS EXPECTED TO BE
FROM THE LATE MRNG INTO THE EARLY AFTN HRS. AT THIS TIME...THE LOW
WILL BE MOVING AWAY FROM THE OCEAN CITY MD AREA...PULLING AWAY FROM
THE COAST AND STARTING TO TAKE THE PRECIP ALONG WITH IT.
SEVERAL ADDITIONAL INCHES OF SNOW WILL ACCUMULATE ACROSS THE
REGION...BRINGING TOTALS TO LIKELY OVER A FOOT ACROSS MUCH OF THE
SHEN VLY AND BETWEEN ONE-TO-TWO FT ALONG THE SURROUNDING
RIDGELINES...JUST UNDER A FOOT ACROSS THE VA PIEDMONT AND JUST INTO
N CNTRL MD...MORE OF A 6-12 INCH SPREAD ALONG THE I-95 CORRIDOR AND
A RAIN/SNOW MIX ALONG THE WRN BAYSHORE COUNTIES AND SRN MD - THOUGH
4-8 INCH TOTAL STILL POSSIBLE AT THE TAIL END OF STORM SYSTEM
LATER IN THE AFTN/EVE.
A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE
MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE
COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY
FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE
BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY
OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW
FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER
INTO THE EARLY MRNG HRS THU.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST
TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH
FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME.
ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION
SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY
FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE
WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE
AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH
SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE
SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS
SHOWING CLEAR TO PARTLY CLOUDY SKIES.
NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN
SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY.
CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST
SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC
HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND
CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S
WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR
I-95.
EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES
SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE.
GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL
WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS
COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
A SNOWSTORM FOR MUCH OF THE AREA TODAY. THE PAST SEVERAL HRS HAS
BEEN THE WARM-UP FOR THE MORE INTENSE VERSION LATER THIS MRNG AND
AFTN. SOLID IFR CONDS ALREADY COVERING THE REGION W/ A FEW LIFR OBS
SCATTERED ABOUT...UNDER THE HEAVIER SNOW BANDS. THE RESPONSIBLE SFC
LOW IS STILL OVER ERN NC BUT WILL MOVE TOWARD THE NORFOLK VA AREA IN
THE COMING HRS...INTENSIFY AND CREATE A STRONGER LOW LEVEL WIND
FIELD BACK ACROSS MD/NRN VA. INTENSE SNOWFALL RATES...GUSTY WINDS
AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK
TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD
THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE
EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND
INTO THU.
PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN
TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY
NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH
PRESSURE THIS WEEKEND.
&&
.MARINE...
GALE FORCE WIND GUSTS WILL BECOME MORE COMMON HEADING INTO THE MRNG
HRS TODAY...AS A SFC LOW MOVES FROM NRN NC TOWARD THE DELMARVA
REGION. BREEZY E-NELY WINDS WILL BECOME INTENSE NLY WINDS WHILE THE
LOW IS MOVING OFF THE COAST LATER THIS MRNG. SOLID GALE GUSTS WILL
STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL
CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE
GALE RANGE OVERNIGHT.
WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT
HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA
CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK.
&&
.HYDROLOGY...
MODEL GUIDANCE REMAINS REMARKABLY CONSISTENT WITH A QPF BULLSEYE IN
THE RAPPAHANNOCK BASIN. AROUND TWO INCHES OF LIQUID/LIQUID EQUIV
PRECIPITATION IS LIKELY THROUGH MUCH OF THAT BASIN. IT LOOKS LIKE
THE MAJORITY OF THAT WILL WIND UP BEING FROM SNOW ESPECIALLY IN
THE UPPER PART. IN ADDITION...SFC TEMPS AND SOIL TEMPS ARE AND
WILL REMAIN ABOVE FREEZING OUTSIDE THE HIGHER ELEVATIONS...SO
THERE WILL BE SOME SOIL INFILTRATION INITIALLY FROM RAIN...LIQUID
FROM SNOW...OR BOTH. THEN WE HAVE TO LOOK AT HOW QUICKLY THE SNOW
MELTS...AND HOW LONG IT TAKES TO START MELTING THE MOUNTAIN SNOWS
TO ADD TO THE PICTURE. THE MOST LIKELY SCENARIO IS FOR THERE TO BE
A GRADUAL MELT...WHICH WOULD NOT POSE MUCH OF A FLOOD THREAT...BUT
THE AFOREMENTIONED UNCERTAINTIES LEND THEMSELVES TO KEEPING AN EYE
ON THE SITUATION THROUGH THE END OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
ANOMALIES HAVE TURNED POSITIVE...CLOSE TO 1 FT ABOVE NORMAL AT 3 AM
ALONG THE WESTERN SHORE OF THE BAY. WITH EASTERLY FLOW PERSISTING
THIS MORNING...ANOMALIES WILL CONTINUE TO CLIMB POSSIBLY ON THE
ORDER OF 1.5 TO 2 FT ABOVE NORMAL. THIS WILL PRODUCE MINOR TIDAL
FLOODING ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY UP THROUGH AT
LEAST ANNE ARUNDEL COUNTY...AND CONFIDENCE IS INCREASING OF THE
MINOR THRESHOLD BEING REACHED TOWARD BALTIMORE DURING HIGH TIDE.
CONFIDENCE DECREASES NORTH OF HERE WITH AN EAST WIND BECOMING
NORTHEAST BY HIGH TIDE TIME. SAME GOES FOR THE UPPER TIDAL
POTOMAC...SO WILL REFRAIN FROM ADVISORY IN THESE AREAS DO TO LOWER
CONFIDENCE BUT WILL NEED TO BE WATCHED.
LATER THIS AFTERNOON AND EVENING WHEN WINDS DO TURN
NORTHERLY...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS
COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER
IN THE UPPER BAY. FORECAST MODEL SHOWS A LITTLE WATER TRAPPING IN
THE LOWERMOST TIDAL POTOMAC THAT KEEPS LEVELS ELEVATED FOR THE
WEDNESDAY EVENING CYCLE THERE. WILL HAVE TO KEEP AN EYE ON THAT.
WINDS TURN OUT OF THE NORTHWEST AFTER THAT...WHICH SHOULD MAKE
EVERYTHING DROP SIGNIFICANTLY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001.
MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501-
502.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007-
009>011-013-014-016>018.
COASTAL FLOOD ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
MDZ014-017-018.
COASTAL FLOOD ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
MDZ011.
VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031-
503-504.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040-
042-050>057-501-502.
WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053-
055-501>506.
MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535-
536.
GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536.
&&
$$
SYNOPSIS...BPP/GMS
NEAR TERM...GMS/KCS
SHORT TERM...BPP
LONG TERM...JRK
AVIATION...JRK/BPP/GMS
MARINE...JRK/BPP/GMS
HYDROLOGY...
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
832 AM EST WED MAR 6 2013
.SYNOPSIS...
STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW
WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD
OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 0830AM...QUICK UPDATE MADE TO MORNING FCST BASED ON CURRENT
RADAR/OBS. RAIN/SNOW LINE IS JUST TO SOUTHEAST OF A LINE FROM
BWI/ADW/DCA. SOUTHEAST OF THIS LINE...MOSTLY RAIN IS FALLING WITH
SURFACE TEMPS IN UPPER 30S...TO EVEN LOW 40S OVER SRN MD.
LOW PRESSURE IS NOW OVER THE NORFOLK METRO AREA...WITH AN EASTERLY
WIND ADVECTING MARINE AIR OVER SRN MD. AS THE BOTH THE SURFACE AND
UPPER LOW MOVE TOWARDS THE NORTH DURING THE DAY TODAY...WINDS ARE
EXPECTED TO BECOME MORE NORTHERLY AND DRAW IN COOLER AIR. FOR THIS
REASON...STILL EXPECTING A CHANGEOVER TO SNOW ALONG AND EAST OF
THE I-95 CORRIDOR. ADJUSTED SNOWFALL TOTALS DOWN S AND E OF
BWI/DCA BASED ON LOWER SNOW ACCUM IN THE MORNING. ALSO ADJUSTED
TOTALS ALONG AND W OF THE BLUE RIDGE BASED ON REPORTS.
PREVIOUS DISCUSSION....
THE TRANSITION BETWEEN PHASES OF THIS INTENSE AND IMPACTFUL
INCOMING SNOWSTORM IS FULLY UNDERWAY. THE INITIAL SFC LOW THAT
DROPPED DOWN FROM THE NRN PLAINS INTO THE UPPER MIDWEST IS ABOUT
TO BE PHASED-OUT. THE NEWER AND STRONGER LOW CURRENTLY OVER THE
RALEIGH NC AREA WILL CREATE A SNOWY AND HAZARDOUS WEDNESDAY FOR
MUCH OF THE MID-ATLC. THE NEXT SEVERAL HOURS WILL BE THE CRITICAL
TRANSITION PERIOD AS THIS LOW INTENSIFIES AND ROTATES DUE NE
TOWARD THE LOWER TIP OF THE DELMARVA PENINSULA AND DEVELOPS HEAVY
SNOW BAND ACROSS THE NWRN QUADRANT OF THE LOW DURING THE DAYTIME
HRS.
THROUGH DAYBREAK...
A REGIONAL VIEW OF THE RADAR RETURNS SHOWS THAT SNOW STILL AFFECTING
MUCH OF THE UPPER MIDWEST...FROM CNTRL IN TO THE APLCNS...BUT THIS
AREA OF PRECIP REGION WILL DISSIPATE IN THE NEXT FEW HRS. ONLY
POCKETS OF HIGHER ELEVATION UPSLOPE SNOW WILL CONTINUE ALONG THE
APLCN CHAIN.
THE FIRST PHASE OF THE SYSTEM THAT BROUGHT LIGHT TO MODERATE SNOW
OVER THE ENTIRE REGION IN JUST THE PAST FEW HOURS IS JUST THE START.
ABOUT A HALF-FOOT OF SNOW HAS ALREADY FALLEN OVER THE HIGHER TERRAIN
OF THE CNTRL APLCNS...TOWARD THE BLUE RIDGE. A FEW INCHES HAVE
BEEN COMMON OVER THE SWRN QUADRANT OF THE CWA THRU 2-3AM. THE
HEAVIER BANDS THAT BROUGHT THIS ACTIVITY ARE NOW SPREADING ACROSS
THE DC/BALT AND THE PIEDMONT AREAS. THIS ACTIVITY WILL CREATE THE
FIRST LAYER OF SNOW AND ALLOW FOR THE INITIAL BASE FOR ACCUMULATIONS
FROM THE SECOND PHASE OF THE STORM.
WINDS HAVE BEEN INTERMITTENTLY INCREASED...NORMALLY W/ SOME OF THE
HEAVIER BANDS BUT THEN DROP BACK DOWN TO 5-10MPH. THESE LOWER WIND
SPEEDS ARE ALLOWING FOR THE RELATIVELY HIGHER VISIBILITIES IN THE
1-2SM RANGE. THIS WILL CHANGE AS WINDS INCREASE AND SNOW
INTENSITIES INCREASE. DETERMINISTIC NAM AND GFS RUNS STILL BULLISH
ON QPF...SO THE CURRENT FORECAST IS A GOOD MIX OF NEAR TERM HI-RES
GUIDANCE...INCLUDING LOCAL VERSION OF THE VARIOUS WRF MEMBERS AND
ESPC THE HRRR WHICH HAS DONE WELL W/ INITIALIZING OVER THE FIRST
PART OF THIS EVENT.
DAYBREAK THROUGH MIDDAY...
IF THEY HAVEN`T ALREADY BY DAYBREAK - CONDITIONS WILL DETERIORATE
RAPIDLY ACROSS MOST - IF NOT ALL - OF THE CWA. LOCALIZED AREAS WILL
RECEIVE BRIEF INTENSE SNOWFALL RATES OF 1-2 INCHES PER HR...POSSIBLY
HIGHER. NOW THAT THE LOW IS ON THE DOORSTEP AND NEAR-TERM GUIDANCE
HAS BEEN INITIALIZING W/ THIS DATA...SOME OF THE HI-RES MEMBERS HAVE
STARTED TO DEPICT ONE LARGE ENCOMPASSING SNOW BAND - ORIENTED ALONG
THE I-95 CORRIDOR BUT STRETCHING OVER THE ENTIRETY OF THE
PIEDMONT/COASTAL COUNTIES...TAPERING OFF TOWARD THE BLUE RIDGE AND
APLCNS. WITHIN THIS LARGER BAND WILL BE THE DYNAMIC HEAVIER BANDS W/
THE HIGHER INTENSITIES AND LOW VISIBILITIES.
WINDS AROUND THIS SECTOR OF THE STORM WILL BE STRENGTHENING W/ SUST
SPEEDS IN THE 15-25MPH RANGE AND PEAK GUSTS IN THE 30-40MPH RANGE.
NEAR-WHITEOUT CONDITIONS ARE STILL IN QUESTION...IN TERMS OF AREA
AND DURATION. THERE WILL BE BRIEF PERIODS OF NEAR-WHITEOUT
CONDITIONS BUT AS FAR WIDESPREAD AND LONG-LIVED DURATIONS...
CONFIDENCE IS LOWER. REGARDLESS...THE HEAVY-WET SNOW AND GUSTY WINDS
WILL CREATE DANGEROUS AND NEAR-IMPOSSIBLE TRAVEL AT TIMES.
MIDDAY THROUGH LATE TONIGHT...
THE HEIGHT OF SNOWFALL RATES AND INTENSITIES ACROSS THE I-95
CORRIDOR...THE METRO AREAS AND THE VA/MD PIEDMONT IS EXPECTED TO BE
FROM THE LATE MRNG INTO THE EARLY AFTN HRS. AT THIS TIME...THE LOW
WILL BE MOVING AWAY FROM THE OCEAN CITY MD AREA...PULLING AWAY FROM
THE COAST AND STARTING TO TAKE THE PRECIP ALONG WITH IT.
SEVERAL ADDITIONAL INCHES OF SNOW WILL ACCUMULATE ACROSS THE
REGION...BRINGING TOTALS TO LIKELY OVER A FOOT ACROSS MUCH OF THE
SHEN VLY AND BETWEEN ONE-TO-TWO FT ALONG THE SURROUNDING
RIDGELINES...JUST UNDER A FOOT ACROSS THE VA PIEDMONT AND JUST INTO
N CNTRL MD...MORE OF A 6-12 INCH SPREAD ALONG THE I-95 CORRIDOR AND
A RAIN/SNOW MIX ALONG THE WRN BAYSHORE COUNTIES AND SRN MD - THOUGH
4-8 INCH TOTAL STILL POSSIBLE AT THE TAIL END OF STORM SYSTEM
LATER IN THE AFTN/EVE.
A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE
MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE
COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY
FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE
BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY
OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW
FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER
INTO THE EARLY MRNG HRS THU.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST
TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH
FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME.
ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION
SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY
FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE
WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE
AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH
SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE
SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS
SHOWING CLEAR TO PARTLY CLOUDY SKIES.
NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN
SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY.
CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST
SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC
HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND
CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S
WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR
I-95.
EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES
SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE.
GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL
WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS
COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
A SNOWSTORM FOR MUCH OF THE AREA TODAY. THE PAST SEVERAL HRS HAS
BEEN THE WARM-UP FOR THE MORE INTENSE VERSION LATER THIS MRNG AND
AFTN. SOLID IFR CONDS ALREADY COVERING THE REGION W/ A FEW LIFR OBS
SCATTERED ABOUT...UNDER THE HEAVIER SNOW BANDS. THE RESPONSIBLE SFC
LOW IS STILL OVER ERN NC BUT WILL MOVE TOWARD THE NORFOLK VA AREA IN
THE COMING HRS...INTENSIFY AND CREATE A STRONGER LOW LEVEL WIND
FIELD BACK ACROSS MD/NRN VA. INTENSE SNOWFALL RATES...GUSTY WINDS
AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK
TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD
THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE
EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND
INTO THU.
PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN
TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY
NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH
PRESSURE THIS WEEKEND.
&&
.MARINE...
GALE FORCE WIND GUSTS WILL BECOME MORE COMMON HEADING INTO THE MRNG
HRS TODAY...AS A SFC LOW MOVES FROM NRN NC TOWARD THE DELMARVA
REGION. BREEZY E-NELY WINDS WILL BECOME INTENSE NLY WINDS WHILE THE
LOW IS MOVING OFF THE COAST LATER THIS MRNG. SOLID GALE GUSTS WILL
STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL
CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE
GALE RANGE OVERNIGHT.
WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT
HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA
CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK.
&&
.HYDROLOGY...
MODEL GUIDANCE REMAINS REMARKABLY CONSISTENT WITH A QPF BULLSEYE IN
THE RAPPAHANNOCK BASIN. AROUND TWO INCHES OF LIQUID/LIQUID EQUIV
PRECIPITATION IS LIKELY THROUGH MUCH OF THAT BASIN. IT LOOKS LIKE
THE MAJORITY OF THAT WILL WIND UP BEING FROM SNOW ESPECIALLY IN
THE UPPER PART. IN ADDITION...SFC TEMPS AND SOIL TEMPS ARE AND
WILL REMAIN ABOVE FREEZING OUTSIDE THE HIGHER ELEVATIONS...SO
THERE WILL BE SOME SOIL INFILTRATION INITIALLY FROM RAIN...LIQUID
FROM SNOW...OR BOTH. THEN WE HAVE TO LOOK AT HOW QUICKLY THE SNOW
MELTS...AND HOW LONG IT TAKES TO START MELTING THE MOUNTAIN SNOWS
TO ADD TO THE PICTURE. THE MOST LIKELY SCENARIO IS FOR THERE TO BE
A GRADUAL MELT...WHICH WOULD NOT POSE MUCH OF A FLOOD THREAT...BUT
THE AFOREMENTIONED UNCERTAINTIES LEND THEMSELVES TO KEEPING AN EYE
ON THE SITUATION THROUGH THE END OF THE WEEK.
&&
.TIDES/COASTAL FLOODING...
ANOMALIES HAVE TURNED POSITIVE...CLOSE TO 1 FT ABOVE NORMAL AT 3 AM
ALONG THE WESTERN SHORE OF THE BAY. WITH EASTERLY FLOW PERSISTING
THIS MORNING...ANOMALIES WILL CONTINUE TO CLIMB POSSIBLY ON THE
ORDER OF 1.5 TO 2 FT ABOVE NORMAL. THIS WILL PRODUCE MINOR TIDAL
FLOODING ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY UP THROUGH AT
LEAST ANNE ARUNDEL COUNTY...AND CONFIDENCE IS INCREASING OF THE
MINOR THRESHOLD BEING REACHED TOWARD BALTIMORE DURING HIGH TIDE.
CONFIDENCE DECREASES NORTH OF HERE WITH AN EAST WIND BECOMING
NORTHEAST BY HIGH TIDE TIME. SAME GOES FOR THE UPPER TIDAL
POTOMAC...SO WILL REFRAIN FROM ADVISORY IN THESE AREAS DO TO LOWER
CONFIDENCE BUT WILL NEED TO BE WATCHED.
LATER THIS AFTERNOON AND EVENING WHEN WINDS DO TURN
NORTHERLY...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS
COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER
IN THE UPPER BAY. FORECAST MODEL SHOWS A LITTLE WATER TRAPPING IN
THE LOWERMOST TIDAL POTOMAC THAT KEEPS LEVELS ELEVATED FOR THE
WEDNESDAY EVENING CYCLE THERE. WILL HAVE TO KEEP AN EYE ON THAT.
WINDS TURN OUT OF THE NORTHWEST AFTER THAT...WHICH SHOULD MAKE
EVERYTHING DROP SIGNIFICANTLY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001.
MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501-
502.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007-
009>011-013-014-016>018.
COASTAL FLOOD ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
MDZ014-017-018.
COASTAL FLOOD ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
MDZ011.
VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031-
503-504.
WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040-
042-050>057-501-502.
WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053-
055-501>506.
MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535-
536.
GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536.
&&
$$
SYNOPSIS...BPP/GMS
NEAR TERM...GMS/KCS
SHORT TERM...BPP
LONG TERM...JRK
AVIATION...JRK/BPP/GMS
MARINE...JRK/BPP/GMS
HYDROLOGY...
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
649 AM EST WED MAR 6 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST WED MAR 6 2013
INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE
NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP
TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS
BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR
OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS
MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION
THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY
SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH.
TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF
THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR
WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH
OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING
ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH.
FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS
AROUND 600MB.
STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING
NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH.
THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING.
MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON
WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS
MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING
THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER
MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE
WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS
SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM
GUIDANCE.
MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK
MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES
WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE
CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF
A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT
GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF
LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI
BORDER.
OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS
ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN.
ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA.
TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL
AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD
LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW
STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING
CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN
SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS
THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE
ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS
A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS
DROP BELOW ZERO IN A FEW SPOTS WELL INLAND.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 534 AM EST WED MAR 6 2013
HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS
EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE
STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL
BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS.
UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN
DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE
AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS
ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET
OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID
TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX
MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN
INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY
FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST
HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG
LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH
HIGHS GENERALLY IN THE LOWER TO MID 30S.
BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE
PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE
MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO
INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN
THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE
SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE
MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL
HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST
FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF
SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST
AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON
SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY
SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE
DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB
TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF
RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST
...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST
HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT
NIGHT.
HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO
SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT
FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE
UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM
SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING
OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR
IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW.
MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE
THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE
ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA
FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL
CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 648 AM EST WED MAR 6 2013
A WEAK TROUGH MOVING THROUGH THE AREA WILL BRING LIGHT SNOW TO ALL
TAF SITES TODAY...AFFECTING IWD AND CMX THIS MORNING...AND SAW
THROUGH THE AFTERNOON. VIS SHOULD REMAIN GENERALLY IN THE IFR
RANGE...WITH CIGS IN THE MVFR RANGE. UPSLOPE WINDS AT ALL SITES WILL
HELP KEEP CIGS LOWER FOR MUCH OF THE DAY. THE TROUGH WILL MOVE EAST
DURING THE DAY...BUT EXPECT LAKE ENHANCED SNOW SHOWERS TO CONTINUE
INTO THE EVENING NEAR LAKE SUPERIOR. VIS SHOULD IMPROVE AT ALL SITES
BY LATE THIS AFTERNOON WHILE CIGS REMAIN IN THE MVFR RANGE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST WED MAR 6 2013
A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW
WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE
THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE
ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS.
EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON
FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL
AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR
AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY
AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...TK
LONG TERM...VOSS
AVIATION...TK
MARINE...TK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
535 AM EST WED MAR 6 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST WED MAR 6 2013
INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE
NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP
TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS
BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR
OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS
MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION
THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY
SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH.
TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF
THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR
WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH
OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING
ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH.
FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS
AROUND 600MB.
STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING
NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH.
THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING.
MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON
WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS
MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING
THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER
MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE
WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS
SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM
GUIDANCE.
MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK
MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES
WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE
CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF
A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT
GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF
LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI
BORDER.
OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS
ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN.
ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA.
TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL
AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD
LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW
STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING
CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN
SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS
THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE
ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS
A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS
DROP BELOW ZERO IN A FEW SPOTS WELL INLAND.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 534 AM EST WED MAR 6 2013
HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS
EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE
STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL
BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS.
UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN
DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE
AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS
ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET
OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID
TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX
MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN
INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY
FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST
HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG
LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH
HIGHS GENERALLY IN THE LOWER TO MID 30S.
BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE
PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE
MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO
INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN
THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE
SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE
MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL
HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST
FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF
SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST
AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON
SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY
SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE
DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB
TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF
RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST
...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST
HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT
NIGHT.
HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO
SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT
FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE
UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM
SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING
OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR
IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW.
MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE
THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE
ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA
FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL
CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1235 AM EST WED MAR 6 2013
DRY AIR CONTINUES TO DELAY THINGS AND PUSHED THE TIMING BACK A BIT.
WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED
MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS
FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS OVERNIGHT WITH -SHSN
DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR BY MORNING UNDER
FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR
OVERNIGHT BEFORE FALLING TO PREVAILING IFR BY MORNING. AT
KSAW...MVFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP LATE TONIGHT.
FAVORABLE CONVERGENT UPSLOPE FLOW WED MORNING WILL RESULT IN CIGS
FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER WED
MORNING INTO THE EARLY AFTERNOON WHERE MVFR CONDITIONS WILL THEN
PREVAIL.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST WED MAR 6 2013
A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW
WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE
THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE
ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS.
EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON
FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL
AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR
AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY
AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...TK
LONG TERM...VOSS
AVIATION...07
MARINE...TK
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
511 AM CST WED MAR 6 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 332 AM CST WED MAR 6 2013
STILL SEEING SOME WEAK BANDING ON RADAR THIS MORNING THAT IS
CORRESPONDING WITH THE FLURRIES BEING REPORTED IN THE SURFACE
OBSERVATIONS. THIS BANDING LOOKS TO BE SET UP UNDER THE CHANNELED
VORT MAX ON THE WESTERN SIDE OF THE VORT. RAP DEPICTS THAT THIS
VORT WILL MOVE EAST OF THE AREA BY LATE MORNING...SO WILL MAINTAIN
SCT FLURRIES OVER THE EASTERN HALF OF THE CWA THROUGH MID MORNING.
SATELLITE STILL SHOWS EXTENSIVE CLOUDINESS OVER MO/IL EARLY THIS
MORNING...WITH THE BACK EDGE OF THE CLOUDINESS MOVING A BIT TO THE
WEST OVER WESTERN MO/EASTERN KS THE PAST FEW HOURS. THERE HAS BEEN
SOME BREAKS SEEN OVER EASTERN IA WHICH IS COMPLICATING THE CLOUD
FORECAST...THOUGH THESE BREAKS MAY FILL BACK IN DURING THE DAY AS
MOIST LOW LEVEL CYCLONIC FLOW REMAINS OVER THE AREA. IT WILL TAKE
MOST OF THE DAY BEFORE THE LOW LEVEL RIDGE CAN MOVE EAST INTO THE
AREA...SO INCREASED CLOUD COVER FOR THE DAY. CONSEQUENTLY...DO NOT
EXPECT MUCH OF A TEMPERATURE RECOVERY GIVEN THE CLOUDS AND
NORTHWESTERLY FLOW OFF THE LINGERING SNOW PACK.
BRITT
&&
.LONG TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 332 AM CST WED MAR 6 2013
UNSEASONABLY COLD WEATHER IS EXPECTED TGT WITH GOOD RADIATIONAL
COOLING AS THE SKY SHOULD CLEAR OUT AND THE SFC WIND SHOULD BECOME
LIGHT AS THE SFC RIDGE AXIS WILL BE RIGHT OVER THE FORECAST AREA
BY 12Z THU. SFC DEW POINTS WILL ALSO BE QUITE LOW IN THE UPPER
TEENS TO LOWER 20S...PLUS PARTS OF NERN AND CNTRL MO AND W CNTRL
IL WILL STILL HAVE SNOW COVER. A WARMING TREND WILL BEGIN ON THU
AS AN UPPER LEVEL RIDGE OVER THE PLAINS MOVES EWD TO OVER MO BY
00Z FRI...AND THE SFC WINDS BECOME SELY OVER A PORTION OF THE
AREA AS THE SFC RIDGE MOVES EAST OF THE REGION. TEMPERATURES ON
FRI SHOULD BE AT OR ABOVE NORMAL WITH A RELATIVELY STRONG UPPER
LEVEL RIDGE OVER MO AND IL...AND SLY LOW LEVEL WINDS BRINGING
WARMER 850 MB TEMPERATURES NWD INTO OUR AREA. SHOWERS MAY MOVE
INTO PORTIONS OF NERN AND CNTRL MO AS EARLY AS SAT AS A SLY LOW
LEVEL JET BRINGS INCREASING LOW LEVEL WAA AND MOISTURE INTO THIS
AREA WELL AHEAD OF THE UPPER LEVEL LOW AND ASSOCIATED SFC LOW
MOVING EWD FROM THE SRN ROCKIES INTO THE SRN PLAINS. THE GFS MODEL
IS A LITTLE QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL.
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD MOVE INTO MUCH OF
THE FORECAST AREA ON SAT NGT. WILL LEAN TOWARD THE SLOWER
SOLUTION OF THE ECMWF MODEL WHICH HAS ABOVE NORMAL TEMPERATURES
CONTINUING ON SUN WITH THE COLD FRONT MOVING ONLY SLOWLY SEWD
THROUGH OUR AREA AS THE UPPER LEVEL LOW REMAINS CLOSED OFF AND W OF
OUR AREA. COLDER AIR SHOULD ADVECT SEWD INTO THE REGION SUN NGT
BEHIND THE SFC LOW AND TRAILING COLD FRONT WITH THE RAIN POSSIBLY
CHANGING TO SNOW ACROSS PORTIONS OF NERN AND CNTRL MO AS WELL AS W
CNTRL IL. COLDER...BELOW NORMAL TEMPERATURES SHOULD OCCUR ON
MONDAY WITH LINGERING SNOW POSSIBLE AS THE UPPER LEVEL LOW/TROUGH
AND ASSOCIATED SFC LOW SHIFT E OF OUR AREA WITH STRONG CAA LIKELY
ON THE BACKSIDE.
GKS
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 510 AM CST WED MAR 6 2013
LARGE AREA OF CLOUDS STILL COVERS MOST OF MO/IL...THOUGH THERE IS
A LARGE BREAK THAT HAS DEVELOPED THE PAST FEW HOURS OVER SOUTHEAST
IA/NORTHERN IL. THIS IS TIMED TO REACH KUIN AROUND 12Z AND THE ST.
METRO TAF SITES AROUND 15Z. LOW LEVELS OF THE ATMOSPHERE REMAIN
VERY MOIST...SO THINK THAT THIS HOLE WILL LIKELY FILL BACK IN...SO
HAVE STAYED WITH PREDOMINANT CEILINGS OF 020-030 WITH TEMPO GROUPS
REFLECTING THE VFR CONDITIONS. WHILE IT WILL LIKELY TAKE UNTIL
LATE AFTERNOON/EVENING BEFORE THE CLOUDS CLEAR OUT OF THE AREA...
SHOULD SEE CIGS CLIMB ABOVE 3000FT BY EARLY AFTERNOON.
NORTHWEST WINDS WILL GUST INTO THE 25KT RANGE EARLY THIS MORNING...
BUT WILL THEN DECREASE THROUGH THE DAY AS A LOW LEVEL RIDGE MOVES
INTO THE AREA FROM THE WEST. THERE IS SOME POTENTIAL THAT SOME FOG
MAY DEVELOP WITHIN THE RIDGE AXIS LATE TONIGHT...PARTICULARLY AT
KCOU WHERE SOME SNOW REMAINS ON THE GROUND. CONFIDENCE IS NOT HIGH
ENOUGH TO INCLUDE IT IN THIS TAF ISSUANCE.
SPECIFICS FOR KSTL...AREA OF CLEARING OVER SOUTHEAST IA/WEST
CENTRAL IL IS TIMED TO REACH THE TERMINAL AROUND 15Z. STILL THINK
THAT LOW LEVELS OF THE ATMOSPHERE ARE MOIST ENOUGH FOR THE AREA OF
CLEARING TO FILL BACK IN THIS MORNING...SO ONLY USED A TEMPO GROUP
TO REFLECT IT. CEILINGS WILL LIKELY INCREASE TO VFR BY THIS
AFTERNOON. WINDS WILL SLOWLY DECREASE TODAY BEFORE BECOMING LIGHT
TONIGHT AS A LOW LEVEL RIDGE AXIS MOVES ACROSS THE AREA.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
554 AM CST WED MAR 6 2013
.AVIATION...
12Z TAFS FOR KOFK...KOMA AND KLNK.
LOW CLOUDS CONTINUED TO HANG TOUGH ACROSS EASTERN NEBRASKA WITH
CIGS RANGING FROM JUST BELOW 1K FT AGL ON NW EDGE TO NEAR 2K FT
AGL ON SERN END. ALTHOUGH WIND FLOW IS WEAK AND FAVORABLE FOR A
CONTINUATION OF CIGS THROUGH MIDDAY AT LEAST...BREAKS IN OVERCAST
HAVE BEEN NOTED OVR WRN IA AND NW MO WHICH LEADS TO A LOW
CONFIDENCE CLOUD FORECAST. WOULD SUSPECT...HOWEVER...THAT EROSION
WILL CONTINUE OR EVEN ACCELERATE AS DAYTIME HEATING COMMENCES
LATER THIS MORNING. SOME REDEVELOPMENT POSSIBLE AGAIN LATER
TONIGHT...ESPECIALLY AT KOFK...BUT FOR NOW KEPT CIGS OUT OF
FORECAST FOR TONIGHT.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 354 AM CST WED MAR 6 2013/
DISCUSSION...
MAIN FORECAST CONCERN TODAY WILL BE THE EXTENT OF LOW CLOUDS AND
THE RESULTING AFFECT ON TEMPERATURES. THEN FOCUS TURNS TO SYSTEM
MOVING INTO THE PLAINS FOR THE WEEKEND.
AN EXPANSIVE AREA OF STRATUS CONTINUES TO MOVES SOUTH FROM THE
EASTERN DAKOTAS AND CURRENTLY COVERS MOST OF THE CWA EXCEPT THE
EXTREME WESTERN COUNTIES. THE RAP SEEMS TO HAVE THE BEST HANDLE
ON THESE CLOUDS AND WILL JUMP ON BOARD WITH THIS
GUIDANCE...KEEPING CLOUD COVER THROUGH AT LEAST 18Z OVER A
MAJORITY OF THE CWA. A SFC HIGH PRESSURE RIDGE CURRENTLY OVER
CENTRAL NEBRASKA WILL CONTINUE TO BUILD EAST AND INHIBIT MIXING
TO SCOUR OUT CLOUDS. THEREFORE THE RAP IDEA OF HANGING ONTO THE
CLOUDS SEEMS FAIR THROUGH MUCH OF THE MORNING HOURS AND POSSIBLY
INTO THE AFTERNOON IN OUR EAST. AS SOUTHERLY LOW LEVEL FLOW
INCREASES LATE THIS AFTERNOON...EXPECT CLOUDS TO MOVE OUT FROM
WEST TO EAST. HAVE REDUCED HIGHS TO A FEW DEGREES BELOW MOS DUE TO
CLOUD COVER.
QUIET CONDITIONS AND A GRADUAL WARMING TREND ARE EXPECTED TODAY
THROUGH FRIDAY AS AN UPPER RIDGE PASSES OVER THE CENTRAL CONUS
THROUGH THIS TIME PERIOD. HIGH TEMPS SHOULD BE IN THE UPPER 40S
AND LOWER 50S BY FRIDAY.
FOCUS TURNS TO LARGE SYSTEM CURRENTLY OFF THE PACIFIC NORTHWEST
COAST. THIS IS FORECAST TO ROUND THE FOUR CORNERS REGION BY
SATURDAY 12Z. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON
PLACEMENT AND TIMING LEADING TO INCREASING FORECASTER CONFIDENCE.
A LEAD SHORTWAVE WILL EJECT INTO THE CENTRAL PLAINS BY FRIDAY
NIGHT WITH A SFC WARM FRONT EXTENDING NORTHEAST AND BISECTING OUR
CWA. THIS BOUNDARY SHOULD BE THE FOCUS FOR PRECIPITATION FRIDAY
NIGHT INTO SATURDAY. BETTER UPPER LEVEL DYNAMICS WILL ADVANCE
INTO THE AREA SATURDAY NIGHT INTO SUNDAY AS THE UPPER LOW KICKS
OUT OF EASTERN COLORADO AND INTO KANSAS. WILL CONTINUE LIKELY POPS
FOR THIS TIME PERIOD. TIGHT BAROCLINIC ZONE WILL REMAIN EXTENDED
ACROSS THE FORECAST AREA WITH SNOW MOST LIKELY TO THE NORTH OF THE
BOUNDARY AND RAIN IN THE SOUTH...WITH A TRANSITION ZONE SOMEWHERE
IN THE MIDDLE. MODELS HAVE BEEN CONSISTENT WITH DROPPING COLDER
AIR SOUTH OVER THE FORECAST AREA SO SNOW COULD BE PRIMARY PCPN
TYPE SAT NIGHT THROUGH SUNDAY NIGHT WHEN DEFORMATION ZONE MOVES
OVERHEAD. HAVE INCREASED THE SFC WINDS ON THE BACKSIDE OF THIS
SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH UNIDIRECTIONAL
NORTHERLY FLOW CREATING QUITE BLUSTERY CONDITIONS. 850MB WIND
SPEEDS ARE FORECAST AROUND 50 KTS OFF BOTH THE 00Z GFS AND 00Z
ECMWF. THIS SAID...IF ANY SNOW IS FALLING...IT WILL BE BLOWING
AROUND.
THIS SYSTEM QUICKLY MOVES EAST SUNDAY NIGHT ENDING PCPN FROM WEST
TO EAST LEAVING NORTHWESTERLY FLOW ALOFT. FORECAST SUB ZERO C 850
MB TEMPS IN ADDITION TO POTENTIAL SNOW COVER WOULD SUGGEST BELOW
NORMAL TEMPS EARLY NEXT WEEK.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
955 AM EST WED MAR 6 2013
.SYNOPSIS...
A POWERFUL LOW PRESSURE SYSTEM OVER SOUTHEAST VIRGINIA WILL MOVE
SLOWLY EAST OUT OVER THE ATLANTIC LATER TODAY THROUGH TONIGHT. DRY
HIGH PRESSURE WILL SLOWLY BUILD OVER THE EASTERN SEABOARD THURSDAY
THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
AS OF 955 AM WEDNESDAY...
REST OF TODAY: STRONG GRADIENT WINDS AND THE CHANCE OF SNOW SHOWERS
OVER NORTH CENTRAL SECTIONS REMAIN SIGNIFICANT FORECAST CONCERNS.
LATEST SURFACE MAP SHOWS THE SURFACE LOW CENTER JUST NORTH OF
WILLIAMSBURG VA. MOSTLY LIGHT SNOW SHOWERS... OCCASIONALLY CHANGING
BACK TO RAIN WHEN RATES DECREASE... CONTINUE TO PIVOT OVER THE FAR
NORTH CENTRAL AND NORTHEAST CWA. WE`VE RECEIVED A FEW REPORTS OF
LIGHT ACCUMULATION ON GRASSY AREAS FROM A FEW SPOTS THIS MORNING...
AND THIS SEEMS TO HAVE BEEN THE CASE BENEATH THE AREAS OF HEAVIER
REFLECTIVITIES... ONE BAND OF WHICH IS PROGRESSING THROUGH FRANKLIN
TOWARD NASH COUNTY. WE ARE STILL CANVASSING THE COUNTIES AND TOWNS
THERE TO DETERMINE THE DEGREE OF IMPACT OF THE SNOW THAT HAS FALLEN
SO FAR... BUT BASED ON THE RADAR TRENDS AND RECENT HRRR RUNS WHICH
SUGGEST THAT SOME OF THE HEAVIER SNOW SHOWERS OVER SOUTH CENTRAL VA
MAY TRACK SOUTH OF THE BORDER... A SHORT-TERM ADVISORY MAY BE NEEDED
HERE. IN ANY CASE... BASED ON THE OBSERVED AND EXPECTED WET BULB
TEMPS THAT SHOULD HOLD VERY CLOSE TO FREEZING OR JUST ABOVE... AND
WITH FAIRLY MILD ROAD TEMPS... ROADS SHOULD BE JUST WET WITH ANY
ACCUMULATION ON THE GRASSY AREAS ONLY. WILL CONTINUE TO MONITOR. THE
WIND ADVISORY WILL REMAIN AS IS. SEVERAL GUSTS OVER 30 KTS HAVE
ALREADY BEEN REPORTED... PRIMARILY IN LOCATIONS THAT HAVE SEEN SOME
SUNSHINE THIS MORNING... IN THE FAR WEST AND ACROSS THE SOUTHERN
CWA. OBSERVED 925 MB TEMPS FROM UPPER AIR SOUNDINGS ARE AROUND 30
KTS... AND AROUND 35-40 KT AT 850 MB... SO WITH GOOD MIXING EXPECT
FREQUENT GUSTS TO AROUND 35-45 MPH. HIGHS FROM 36-40 NORTH TO AROUND
50 IN THE SOUTH. -GIH
TONIGHT...SHOULD SEE PRECIP CHANCES END EARLY IN THE FAR NE AS THE
LOW PRESSURE SYSTEM PULLS FARTHER AWAY. CLEARING SKIES WILL TREND
EWD DURING THE NIGHT. DUE TOT HE LARGE WIND FIELD ASSOCIATED WITH
THE SYSTEM...EXPECT WINDY/BREEZY CONDITIONS TO PERSIST THROUGH MOST
OF THE NIGHT. THIS MIXING WILL PREVENT TEMPS FROM REACHING THEIR
FULL COOLING POTENTIAL. MIN TEMPS INT HE 30-35 DEGREE RANGE.
THURSDAY...WE WILL REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW
THOUGH THE ASSOCIATED SUBSIDENCE ON THE BACK SIDE SHOULD MAINTAIN
CLEAR SKIES OVER MOST OF THE REGION. NLY WINDS WILL GUSTS TO AROUND
25 KTS...ESPECIALLY IN THE MORNING...AND MAINLY EAST OF HIGHWAY 1.
850MB THERMAL TROUGH AND ASSOCIATED LOW LEVEL CAA WILL PERSIST
THROUGH THU. THIS YIELDS LOW LEVEL THICKNESSES ABOUT 25M BELOW
NORMAL. THIS WOULD SUGGEST MAX TEMPS ABOUT 6-9 DEGREES BELOW NORMAL.
FAVOR MAX TEMPS ABOUT 4 DEGREES BELOW GUIDANCE...RANGING FROM NEAR
50 FAR NE TO THE MID 50S SOUTH.
THURSDAY NIGHT...SURFACE HIGH PRESSURE WILL BEGIN TO INFLUENCE OUR
SENSIBLE WEATHER. PRESSURE GRADIENT ANALYSIS SUGGEST SOME POTENTIAL
FOR A LIGHT WIND THROUGH THE NIGHT. IF SFC WIND ABLE TO
DECOUPLE...COULD SEE TEMPS FALL ABOUT 3-4 DEGREES COOLER THAN
CURRENTLY FORECAST. FOR NOW...WILL MAINTAIN MIN TEMPS NEAR 30 TO
LOWER 30S. -WSS
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 AM WEDNESDAY...
FRIDAY AND FRIDAY NIGHT:
VERTICALLY STACKED LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO
HANG AROUND SEVERAL HUNDRED MILES OFF THE MID ATLANTIC COAST ON
FRIDAY... BEFORE PICKING UP SOME EAST/EAST-SOUTHEASTWARD MOMENTUM ON
FRIDAY NIGHT AS ADDITIONAL S/W ENERGY IN THE FORM OF A BIT WEAKER
CLOSED LOW DIVES SOUTHEASTWARD FROM THE GREAT LAKES REGION THURSDAY
NIGHT INTO FRIDAY (BEFORE BEING ABSORBED BY THE DEEP CYCLONIC VORTEX
OFF THE MID ATLANTIC COAST LATE FRIDAY INTO FRIDAY NIGHT). THIS
ADDITIONAL ENERGY HAS TRENDED A BIT FURTHER WESTWARD WITH ITS
TRACK... YET STILL EXPECTED TO ONLY SIDE SWIPE OUR COASTAL PLAIN AND
NORTHEASTERN PIEDMONT COUNTIES FRIDAY INTO FRIDAY EVENING. GIVEN THE
OVERALL LACK OF MOISTURE EXPECTED ACROSS OUR AREA AND THE CURRENT
TRACK OF THE DISTURBANCE EXPECT WE SHOULD REMAIN DRY... WITH ONLY A
POSSIBLE INCREASE IN SOME CLOUD COVER ON FRIDAY AFTERNOON INTO THE
EVENING ACROSS EASTERN PORTIONS OF CENTRAL NC. HOWEVER... THE CLOUD
COVER COULD HAVE AN IMPACT ON HIGH TEMPERATURES FOR FRIDAY ACROSS
EASTERN/NORTHEASTERN PORTIONS OF THE RAH CWA. PLAN TO GO ON THE
COOLER SIDE OF GUIDANCE FOR MOST OF THE AREA AGAIN GIVEN THIS ALONG
WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO RUN SOME 20 TO
30 METERS BELOW NORMAL FOR THIS TIME OF YEAR... PLUS A POSSIBLE SNOW
PACK TO THE NORTH OF THE CWA WITH CONTINUED NORTH-NORTHWESTERLY LOW
LEVEL FLOW. THIS YIELDS HIGH TEMPS FROM AROUND 50 NE TO THE UPPER
50S SW. IN ADDITION TO THE CHILLY TEMPS... EXPECT WE SHOULD CONTINUE
TO HAVE WINDS IN THE 10 TO 15 MPH RANGE... WITH GUSTS AS HIGH AS 25
MPH.
ANY CLOUD COVER ASSOCIATED WITH THE AFOREMENTIONED DISTURBANCE
SHOULD BEGIN TO SHIFT TO THE EAST OF THE AREA... WITH SUBSIDENCE IN
THE WAKE OF THE DISTURBANCE (NAM WOULD SUGGEST A BIT SLOWER TIMING
BUT APPEARS TO BE A SLOW OUTLIER WRT THE TIMING OF THE DISTURBANCE).
WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA AND CLEARING SKIES
EXPECT WE WILL SEE TEMPS FALL INTO THE UPPER 20S TO LOWER 30S FOR
LOWS SATURDAY MORNING... WITH A LIGHT NORTH-NORTHWESTERLY BREEZE
OVERNIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...
S/W RIDGING IS EXPECTED TO BUILD ACROSS THE REGION FOR THE
WEEKEND... WHILE SURFACE HIGH PRESSURE MOVES ACROSS THE AREA AND
OFFSHORE. THIS WILL RESULT IN QUITE WEATHER ACROSS CENTRAL NC THIS
WEEKEND... WITH A WARMING TREND. EXPECT HIGH TEMPS ON SATURDAY WILL
BE IN THE MID TO UPPER 50S... WITH MAYBE A FEW LOCATIONS TOUCHING 60
ACROSS THE FAR SOUTH OR SOUTHWEST WITH MOSTLY SUNNY SKIES. HIGH
SUNDAY ARE EXPECTED TO BE EVEN WARMER... AS AFTERNOON LOW LEVEL
THICKNESS VALUES ARE EXPECTED TO FINALLY BE SLIGHTLY ABOVE NORMAL.
THUS... EXPECT HIGH TEMPS WILL WARM INTO THE LOWER TO MID 60S BY
SUNDAY AFTERNOON WITH INCREASING HIGH LEVEL CLOUD COVER. LOWS SUNDAY
MORNING ARE EXPECTED TO BE IN THE LOWER TO MID 30S... WITH EXCELLENT
RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT AND
VARIABLE TO CALM WINDS AS HIGH PRESSURE ALOFT AND THE SURFACE WILL
SETTLE OVER THE AREA.
THE NEXT SYSTEM IS EXPECTED TO MOVE INTO THE AREA EARLY NEXT WEEK AS
A DEEP TROUGH AND ASSOCIATED COLD FRONT SHIFT EASTWARD AND
EVENTUALLY ACROSS THE REGION. THE OPERATIONAL GFS AND ECMWF HAVE
COME INTO MUCH BETTER AGREEMENT ON THE TIMING OF THE SYSTEM... AND
NOW BOTH SHOW AT LEAST SOME PHASING/INTERACTION OF THIS SYSTEM
(WHICH ORIGINATES FROM A CLOSED LOW IN THE SOUTHWESTERN U.S. LATE
THIS WEEK) WITH A NORTHERN STREAM TROUGH. BOTH THE 00Z ECMWF AND 00Z
GFS SHOW AN AREA OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS MOVING
ACROSS THE AREA LATE MONDAY AFTERNOON INTO TUESDAY MORNING... ALONG
WITH THE PASSAGE OF A STRONG COLD FRONT BY TUESDAY MORNING. WPC
(FORMERLY KNOW AS HPC... NOW THE WEATHER PREDICTION CENTER) PREFERS
A BIT SLOWER TIMING... LAGGING THE TIMING OF THE FRONT AND CONTINUED
CHANCES FOR SHOWERS AND POSSIBLY STORMS INTO THE DAY TUESDAY... AS
THEY PREFER THE EUROPEAN CENTRE ENSEMBLE MEAN AS THEY NOTED IT
OUTSTANDING PERFORMANCE WITH THE SYNOPTIC FLOW OF LATE. THUS... WILL
TREND THE TIMING A BIT SLOWER THAN THE CURRENT OPERATIONAL MODELS
ADVERTISE... WITH A GOOD CHANCE OF RAIN STILL LATE MONDAY INTO
TUESDAY MORNING. EXPECT HIGHS TO BE IN THE 60S TO POSSIBLY 70S EAST
MONDAY... WITH UPPER 50S TO 60S TUESDAY (HIGHLY DEPENDENT ON THE
TIMING OF THE FRONT). LOWS EARLY NEXT WEEK ARE EXPECTED TO BE IN THE
40S TO EVEN AROUND 50 ON TUESDAY MORNING (AGAIN TIED TO THE EVENTUAL
TIMING OF THE FRONT).
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 655 AM WEDNESDAY...
CEILINGS HAVE IMPROVED ACROSS MUCH OF CENTRAL NC SINCE 3 AM WITH
MOST LOCALES IN THE WEST INCLUDING KINT AND KGSO REPORTING VFR
CEILINGS. ACROSS THE EAST...CEILINGS STILL MVFR BUT SHOULD GRADUALLY
LIFT TO HIGH END MVFR/LOW END VFR BY 15-18Z. SCATTERED RAIN AND/OR
SNOW SHOWERS WILL ROTATE EWD ACROSS THE REGION THIS MORNING...AND
MAINLY ACROSS THE NE PIEDMONT AND NORTHERN COASTAL PLAIN THIS
AFTERNOON.
VERY WINDY CONDITIONS WILL OCCUR SHORTLY AS A DEEP LOW PRESSURE
SYSTEM MOVES EWD AND TAKES A POSITION JUST OFF THE VA-NC COAST. SFC
WINDS WILL VEER TO A MORE NW DIRECTION WITH SUSTAINED WINDS NEAR
20KTS AND FREQUENT GUSTS AROUND 40KTS. A SPORADIC GUST NEAR 50KTS
CANNOT BE RULED OUT. THESE WINDS MAY CAUSE CROSSWIND ISSUES AT
SEVERAL TERMINALS TODAY.
THE STRONG UPPER LEVEL LOW WILL SLOWLY TRAVERSE EWD TONIGHT THROUGH
THU. SUBSIDENCE BEHIND THE DEPARTING LOW WILL AID TO
DIMINISH/DISSIPATE THE CLOUD COVER WEST-TO-EAST. WHILE CLOUDS WILL
DEPART LATER TONIGHT...WINDY CONDITIONS WILL LINGER WELL INTO
TONIGHT WITH BREEZY CONDITIONS LIKELY ON THURSDAY. THE BREEZY
CONDITIONS SHOULD ABATE BY THU NIGHT AS HIGH PRESSURE BEGINS TO
EXERT ITS INFLUENCE. VFR CONDITIONS EXPECTED ACROSS THE REGION LATER
TONIGHT AND PERSISTING INTO SUNDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD/WSS
SHORT TERM...BSD
LONG TERM...BSD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
445 AM CST WED MAR 6 2013
.DISCUSSION.../ISSUED AT 445 AM CST/
LOOKS LIKE A QUIET COUPLE OF DAYS ACROSS THE REGION...BUT THAT DOES
NOT MEAN THE FORECAST IS WITHOUT ITS CHALLENGES. OF PRIMARY CONCERN
TODAY IS WIDESPREAD STRATUS WHICH IS NOW STUCK UNDER SURFACE RIDGE
ADVANCING SLOWLY EASTWARD TODAY. OTHER THAN HIGH-RESOLUTION SHORT
RANGE MODELS...WHICH SEEM TO HAVE BETTER GRASP ON CURRENT REALITY...
HAVE LITTLE USEFUL GUIDANCE TO FOLLOW REGARDING PERSISTENCE OF THE
LOW LEVEL MOISTURE. THUS FOLLOWED MORE PESSIMISTIC RAP/HRRR VIEW...
HOLDING ONTO EXTENSIVE CLOUD COVER MUCH OF THE DAY WITH POSSIBILITY
OF SOME HOLES DEVELOPING IN THE LATE AFTERNOON AS MARCH SUN HAS A
CHANCE TO ERODE AROUND ANY BREAKS WHICH MAY DEVELOP. GREATER CLOUD
COVER WILL LEAD TO COOLER TEMPS...THOUGH PREVIOUS FORECAST ALREADY
ON THE COOL SIDE WITH LIGHT FLOW ACROSS THE EAST SO DID NOT LOWER
HIGHS TOO MUCH AT THIS POINT.
FOR TONIGHT...NAM LOW LEVEL MOISTURE HINTS AT POTENTIAL FOR STRATUS
TO REDEVELOP ACROSS CENTRAL SD AS RETURN SOUTHERLY FLOW DRAWS DEEPER
MOISTURE NORTHWARD BEHIND THE DEPARTING RIDGE. IF THIS DOES DEVELOP
IT COULD LINGER INTO AT LEAST MIDDAY THURSDAY...AGAIN IMPACTING HIGH
TEMPERATURES AND COOLED HIGHS IN THE WEST BY A FEW DEGREES...THOUGH
WITH 925MB TEMPERATURES ANYWHERE FROM 4-6C...COULD STILL MIX INTO
THE MID TO UPPER 40S WEST OF THE JAMES RIVER.
ATTENTION THEN TURNS TO WEEKEND SYSTEM...WHICH MODELS HAVE COME INTO
SLIGHTLY BETTER AGREEMENT ON WHEN COMPARED TO PAST COUPLE OF NIGHTS.
FAVORED SOLUTION DEPICTS STRONGER BUT PROGRESSIVE NORTHERN STREAM
TROUGH MOVING EAST ACROSS NORTH DAKOTA/MINNESOTA SATURDAY/SATURDAY
NIGHT...WHICH DOES NOT ALLOW SOUTHERN STREAM CUTOFF LOW TO SWING
NORTH AND STRENGTHEN AS HAS BEEN SEEN IN PREVIOUS ECMWF RUNS. THIS
SOLUTION DOES GIVE THIS AREA A GOOD CHANCE OF SOME DECENT PRECIP...
WITH GOOD CONSENSUS POINTING TO LATE FRIDAY NIGHT THROUGH SATURDAY
NIGHT AS PERIODS WITH GREATEST POTENTIAL.
COULD SEE SOME LIGHT PRECIP BREAK OUT ACROSS THE WEST ALREADY BY
FRIDAY AFTERNOON...AS BROAD WARM ADVECTION BEGINS TO KICK IN. THIS
BROAD LIFT ACROSS INVERTED TROUGH REMAINS PERSISTENT INTO FRIDAY
NIGHT...WITH GROWING CONFIDENCE FOR BUMPING POPS INTO LIKELY RANGE
ACROSS MUCH OF THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL CARRY
LIKELY POPS INTO SATURDAY NIGHT OVER THE SOUTHEAST HALF OF THE CWA
AS BOUNDARY IS PULLED EAST OF THE AREA BY DEPARTING NORTHERN STREAM
WAVE.
WHILE CONFIDENCE IN PRECIPITATION CHANCE IS GROWING...PRECIPITATION
TYPE BECOMES A HUGE QUESTION MARK. GFS/ECMWF BOTH PUMP WARM AIR WELL
NORTH ACROSS THE REGION...WITH FREEZING LINE NEAR ND/SD BORDER AT
850MB...AND NEAR THE NORTHERN EDGE OF OUR FORECAST AREA AT 925MB BY
FRIDAY EVENING. CONTINUED SOUTHERLY FLOW ACROSS THE AREA FRIDAY
NIGHT KEEPS THE WARM LAYER LOCKED IN PLACE AT LEAST INTO SATURDAY
MORNING...WITH COOLING ONLY TAKING PLACE IN THE WEST BY SATURDAY
AFTERNOON/EVENING AS INVERTED TROUGH BEGINS TO ADVANCE EASTWARD.
SURFACE TEMPERATURES THEN BECOME FOCUS AND FOR NOW HAVE SUB-FREEZING
TEMPERATURES ACROSS FAR WESTERN AND NORTHERN CWA FRIDAY NIGHT INTO
SATURDAY...WITH COLD AIR COLLAPSING SOUTHWARD SATURDAY NIGHT BEHIND
DEPARTING TROUGH. FORECAST SOUNDINGS SUGGEST POTENTIAL FOR FREEZING
RAIN IN THE FAR NORTHERN/WESTERN SECTIONS GIVEN THE COLDER SURFACE
TEMPERATURES TOPPED BY WARM LAYER ABOVE 925MB. HOWEVER...STILL HAVE
ENOUGH UNCERTAINTY IN LOW LEVEL TEMPS AT THIS RANGE THAT DECIDED TO
HOLD OFF MENTIONING FREEZING RAIN FOR NOW...INSTEAD GOING WITH RAIN
OR SNOW WORDING ACROSS OUR NORTH AND WEST...GENERALLY IN THOSE AREAS
NORTHWEST OF INVERTED TROUGH. WILL ADD MENTION OF FREEZING RAIN TO
THE HWO THIS MORNING THOUGH...TO HEIGHTEN AWARENESS OF POTENTIAL FOR
ICING GIVEN TIMING OF THIS EVENT COINCIDING WITH SOUTH DAKOTA GIRLS
BASKETBALL TOURNAMENT TAKING PLACE IN VARIOUS LOCATIONS INCLUDING
HURON THIS WEEKEND.
BY SATURDAY NIGHT/SUNDAY...COOLING BEHIND THE SYSTEM SHOULD CHANGE
PRECIP OVER TO SNOW...THOUGH PRECIP SHOULD ALSO BE WANING THROUGH
THAT PERIOD SO NOT EXPECTING LARGE AMOUNTS OF SNOWFALL AT THIS TIME.
GENERALLY QUIET WEATHER RETURNS FOR EARLY NEXT WEEK. COULD SEE SOME
LIGHT PRECIP IN NORTHWEST FLOW PATTERN...BUT GIVEN SOME UNCERTAINTY
IN PATTERN AND AVAILABLE MOISTURE...WILL KEEP DRY FOR NOW WITH
TEMPERATURES REMAINING ON THE COOL SIDE OF SEASONAL NORMALS.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
STRATUS HAS CONTINUED TO EXPAND WITH DECREASING WINDS AND DIRECTION
BECOMING MORE NORTHEASTERLY. MODELS NOT HANDLING THE STRATUS WELL
AT ALL...WITH THE RAP BEING THE ONLY MODEL SUGGESTING STRATUS
CURRENTLY EXISTS ACROSS THE AREA. HAVE KEPT STRATUS ACROSS THE AREA
THROUGH THE OVERNIGHT...WITH CEILINGS LOWERING SLIGHTLY AROUND
SUNRISE. MODEL SOUNDINGS SUGGEST OUTSIDE CHANCE OF STRATUS LOWERING
TO THE GROUND NEAR KHON...BUT CONFIDENCE NOT THERE AT THIS POINT TO
PUT INTO THE TAF. AT KFSD AND KSUX...STRATUS MAY DIP INTO THE IFR
RANGE BEFORE RECOVERING INTO THE MVFR CATEGORY. WILL BE HARD TO
SHAKE THE STRATUS TOMORROW WITH LIGHT SOUTHEASTERLY FLOW
DEVELOPING...AND KEPT STRATUS THROUGHOUT THE DAY. SOUNDINGS DON/T
HAVE MUCH TO WORK OFF OF BY TOMORROW EVENING...BUT KEPT STRATUS WITH
REINFORCING SOUTHEASTERLY FLOW.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
513 AM CST WED MAR 6 2013
.SHORT TERM...TO0DAY THROUGH FRIDAY
328 AM CST WED MAR 6 2013
FORECAST CONCERNS ARE ON FOG/FREEZING FOG POTENTIAL TONIGHT INTO
THURSDAY MORNING AND TEMPERATURES THROUGH FRIDAY. FOCUS THEN QUICKLY
TURNS TO PRECIPITATION TYPE CONCERNS THIS WEEKEND AND THE POTENTIAL
FOR MODERATE TO HEAVY RAINFALL ACROSS PARTS OF THE AREA.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED LOW
PRESSURE OVER THE CENTRAL APPALACHIANS. A TROUGH WAS NOTED ALONG
THE MINNESOTA/ONTARIO BORDER. AN UPPER RIDGE WAS BUILDING ACROSS
THE WESTERN CONUS WITH A TROUGH MOVING ONTO THE WEST COAST. SURFACE
OBSERVATIONS INDICATED A RIDGE OF HIGH PRESSURE EXTENDING FROM THE
THE DAKOTAS SOUTH THROUGH THE SOUTHERN PLAINS. A SURFACE LOW WAS
NOTED OVER VIRGINIA WITH AN INVERTED TROUGH EXTENDING NORTHWEST
INTO FAR SOUTHEAST WISCONSIN.
THE TROUGH ALONG THE MINNESOTA/ONTARIO BORDER WILL PROGRESS EAST
TODAY ACROSS LAKE SUPERIOR AS THE SURFACE RIDGE EDGES EAST INTO
THE UPPER MISSISSIPPI RIVER VALLEY. THE MAIN FORECAST CHALLENGE
TODAY WILL BE CLOUD COVER. THERE ARE CURRENTLY PLENTY OF HOLES IN
THE STRATUS LAYER OVER EASTERN MINNESOTA INTO SOUTHWEST WISCONSIN.
FORECAST SOUNDINGS SHOW LOW LEVEL CLOUDS LINGERING THROUGH THE
MORNING HOURS BEFORE FINALLY CLEARING LATE THIS AFTERNOON. THE
FORECAST MODELS HAVE BEEN STRUGGLING WITH DEWPOINTS LATELY SO NOT
SOLD ON THE CLOUDS HOLDING ON AS LONG AS THE MODELS SUGGEST.
DECIDED TO GO WITH HIGHER CLOUD COVER THIS MORNING OVER THE
PREVIOUS FORECAST...WITH CLEARING OCCURRING FROM WEST TO EAST
DURING THE MID TO LATE AFTERNOON HOURS. THE NEXT CONCERN IS THE
POTENTIAL FOR FOG/FREEZING FOG TONIGHT. FOG WOULD BE MORE
FAVORABLE IF THE CLOUDS HOLD ON TODAY. SREF GUIDANCE AND FORECAST
SOUNDINGS CONTINUE TO SUGGEST FOG DEVELOPMENT TONIGHT. LOOKING
BACK TO THE WEST...UNDER THE SURFACE RIDGE...FOG HAS DEVELOPED.
THE SREF PROBABILITIES ARE CAPTURING THIS SO FEEL THEY ARE DOING A
DECENT JOB ON CAPTURING THE FOG. WILL MAINTAIN AREAS OF FOG IN THE
FORECAST OVERNIGHT INTO THURSDAY MORNING. VISIBILITIES COULD BE
REDUCED TO LESS THAN 1/2 MILE. ALSO...THE FOG COULD FREEZE TO
OBJECTS CREATING HOAR FROST. SOME LIGHT ICING MAY OCCUR ON AREA
ROADS...BUT THE RECENTLY APPLIED TREATMENT ON THE ROADS COULD
REALLY LIMIT ICING POTENTIAL. PLAN ON LOWS FALLING INTO THE SINGLE
DIGITS TONIGHT. FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH
CENTRAL WISCONSIN WILL SEE TEMPERATURES FALL INTO THE SINGLE DIGITS
BELOW ZERO.
HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY
PROVIDING QUIET WEATHER. LOOK FOR MOSTLY SUNNY SKIES ON THURSDAY
WITH HIGHS IN THE UPPER 20S TO LOWER 30S. SURFACE HIGH PRESSURE IS
EXPECTED TO SLIDE EAST OF THE AREA ON FRIDAY AS A POTENT TROUGH
DIVES INTO THE SOUTHWEST CONUS. MEANWHILE LOW PRESSURE DEVELOPS
OVER EASTERN COLORADO AS A WARM FRONT LIFTS NORTH OUT OF THE
CENTRAL PLAINS. TWO MAIN FEATURES TO WATCH CLOSELY ON FRIDAY...A
NORTHERN STREAM TROUGH DIVING SOUTH OUT OF CENTRAL SASKATCHEWAN
AND THE SOUTHWEST LOW LIFTING NORTHEAST TOWARD THE REGION. THE
WARM FRONT LOOKS TO LIFT NORTH INTO SOUTHERN MINNESOTA/SOUTHERN
WISCONSIN FRIDAY NIGHT INTO SATURDAY MORNING THEN LIFTING NORTH
THROUGH THE DAY ON SATURDAY. THE NORTHERN STREAM WAVE AND ENERGY
EJECTING OUT OF THE SOUTHWEST WILL INTERACT WITH THE FRONT
BRINGING PRECIPITATION TO THE AREA. WARM AIR ALOFT WILL SURGE INTO
THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT LEADING TO A MIX
OF PRECIPITATION TYPES. A MIX OF FREEZING RAIN...SLEET AND SNOW IS
EXPECTED FRIDAY EVENING INTO EARLY SATURDAY MORNING SWITCHING OVER
TO MAINLY RAIN DURING THE DAY ON SATURDAY. SOME ICE ACCUMULATION
IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A MOISTURE RICH
AIRMASS MOVES INTO THE AREA DURING THE DAY ON SATURDAY WITH
PRECIPITABLE WATER VALUES APPROACHING 270 PERCENT OF NORMAL.
ALSO...TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO
LOWER 40S. 925/850 MB MOISTURE TRANSPORT FOCUSES INTO SOUTHERN
WISCONSIN AND FAR NORTHEAST IOWA SATURDAY INTO SATURDAY NIGHT.
PERIODS OF MODERATE TO HEAVY RAINFALL LOOK POSSIBLE SATURDAY INTO
SATURDAY NIGHT LEADING TO LOCALIZED FLOODING AND ICE JAMS ON AREA
RIVERS. FORECAST MODELS ARE JUST STARTING TO COME INTO AGREEMENT
ON THIS WARMER AND WET SOLUTION SO WILL HAVE TO KEEP A CLOSE WATCH
ON THE NEXT FEW RUNS.
.LONG TERM...SATURDAY THROUGH TUESDAY
328 AM CST WED MAR 6 2013
06.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY INTO
SATURDAY NIGHT BUT THEN START TO DIVERGE SUNDAY INTO EARLY MONDAY.
THE ECMWF SHIFTS THE BOUNDARY SOUTHEAST AND EAST OF THE AREA AS AN
UPPER LOW WRAPS UP OVER THE OHIO RIVER VALLEY. THE GFS LEANS TOWARD
THIS SOLUTION BUT IT IS FASTER THAN THE ECMWF...TAKING THE LOW
NORTH INTO THE EASTERN GREAT LAKES EARLY ON MONDAY. THE GEM OFFERS
A DIFFERENT SOLUTION WITH THE LOW TAKING SHAPE OVER NORTHERN
ILLINOIS WHICH WOULD BRING SIGNIFICANT SNOWFALL TO NORTHERN
WISCONSIN THROUGH SOUTHERN/CENTRAL MINNESOTA. HAVE LEANED TOWARD A
MODEL CONSENSUS BLEND APPROACH MONDAY INTO TUESDAY WITH CHANCES
FOR SNOW MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE AREA. SNOW
CHANCES WILL CONTINUE ACROSS NORTH CENTRAL WISCONSIN ON TUESDAY AS
SHORTWAVE MOVES ACROSS NORTHERN WISCONSIN. PLAN ON TEMPERATURES
COOLING SLIGHTLY EARLY NEXT WEEK WITH HIGHS FALLING INTO THE 30S
AND LOWS IN THE TEENS TO LOWER 20S.
&&
.AVIATION...TODAY AND TONIGHT
513 AM CST WED MAR 6 2013
THE MAIN AVIATION CONCERNS ARE WHEN WILL THE MVFR STRATUS CLEAR
OUT AND POTENTIAL FOR FOG TONIGHT.
MVFR STRATUS ENCOMPASSES BOTH TAF SITES EARLY THIS MORNING...
THOUGH THERE ARE SOME POCKETS OF CLEAR SKIES ACROSS CENTRAL AND
EASTERN MINNESOTA. ANTICIPATING THAT THE COMBINATION OF SUNSHINE
AND HIGH PRESSURE BUILDING IN FROM THE PLAINS WILL SLOWLY BUT
SURELY BREAK UP THE STRATUS. THE POCKETS OF CLEAR SKIES...IF THEY
CAN HOLD TOGETHER UNTIL THE SUN COMES UP...WILL HELP AS WELL TO
MIX OUT THE STRATUS. KEPT THE PREVIOUS FORECAST IDEA OF A LATE
SCATTERING OUT TREND...BETWEEN 23-00Z. PLENTY OF UNCERTAINTY
EXISTS ON THIS...HOWEVER...AND IT COULD CLEAR EARLIER OR LATER. IT
DOES APPEAR THAT EVEN IN THE PESSIMISTIC CLEARING SCENARIO...THAT
BY 06Z BOTH TAF SITES WOULD BE CLEARED OUT. WITH LIGHT WINDS...THE
RIDGE AXIS IN PLACE AND LINGERING LOW LEVEL MOISTURE...CONCERN
THEN SHIFTS TO FOG. CERTAINLY POTENTIAL FOR DENSE FOG
FORMATION...ESPECIALLY IF THE LATE IN THE DAY CLEARING OCCURS AS
FORECAST. FOR NOW INCLUDED MVFR BR AT BOTH SITES...BUT AGAIN THIS
COULD END UP LOWER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
328 AM CST WED MAR 6 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1103 AM MST WED MAR 6 2013
.UPDATE...AMENDED THE ZONES FOR SLIGHTLY COOLER TEMPERATURES ON
PLAINS TODAY...AND STRONGER SOUTHEAST WINDS FAR NORTHEAST PLAINS.
&&
.AVIATION...SOUTHEAST TO NORTHEAST WINDS TODAY WILL GIVE WAY TO
DRAINAGE WINDS TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 1000 AM MST WED MAR 6 2013/
UPDATE...WILL CLOSELY WATCH MIXING TODAY...MID SHIFT DID
DELINIATE FOR SNOW ON GROUND WITH COOLER MAXES FROM SOUTHERN WELD
TO NORTHEASTERN ELBERT COUNTIES. THERE IS ALSO SOME CLOUDS TO
ACCOUNT FOR IN THESE AREAS. OTHERWISE NO CHANGES EXPECTED.
AVIATION...A BIT OF HAZE AT KDIA WILL DISSIPATE WITH MIXING
TODAY...SO LOOKING FOR DRY VFR CONDITIONS WITH LIGHT WINDS.
PREV DISCUSSION... /ISSUED 408 AM MST WED MAR 6 2013/
SHORT TERM...SWLY FLOW ALOFT WILL DEVELOP OVER THE AREA AS THE
UPPER LEVEL RIDGE SHIFTS EAST. SOME HIGHER LEVEL CLOUDS WILL BE
POSSIBLE OTHERWISE IT WILL REMAIN DRY THRU TONIGHT. ONCE AGAIN
HIGH TEMPS THIS AFTN WILL BE THE MAIN ISSUE. SOME DEEPER SNOW
COVER STILL RESIDES OVER SRN WELD...CNTRL AND ERN PORTIONS OF ADAMS
AND ARAPAHOE ALONG WITH ELBERT COUNTIES WHICH WILL AFFECT AFTN
HIGHS IN THESE AREAS AS READINGS MAY NOT GET OUT OF THE 40S.
MEANWHILE NR THE FOOTHILLS LIGHT WLY DOWNSLOPE FLOW WILL DVLP
WHICH MAY ALLOW FOR HIGHS TO REACH THE LOWER 60S OVER THE WRN AND
SRN SUBURBS OF DENVER. THUS WILL SEE QUITE A TEMP DIFFERENCE ALONG
THE FRONT RANGE THIS AFTN. OVER THE PLAINS WHERE NO SNOW COVER
EXISTS WINDS WILL BE MAINLY SELY SO WILL KEEP AFTN HIGHS IN THE
LOWER TO MID 50S EXCEPT OVER SRN LINCOLN COUNTY WHERE LOWER 60S
WILL BE POSSIBLE DUE TO SWLY LOW LVL WINDS. FOR TONIGHT MAY SEE
SOME PATCHY FOG DVLP OVER THE FAR NERN PLAINS AFTER MIDNIGHT.
LONG TERM...THURSDAY WILL BE DRY AND WARM AS SOUTHWESTERLY FLOW
ALOFT COVERS THE STATE. FRIDAY WILL BE A TRANSITIONAL DAY AS
SOUTHWEST FLOW ALOFT CONTINUES BUT MOISTURE BEGINS INCREASING
AHEAD OF A POTENT UPPER LOW MOVING OVER THE DESERT SOUTHWEST. AND
SATURDAY LOOKS LIKE IT WILL BE THE MOST CRITICAL DAY OF THIS
FORECAST PACKAGE. EACH OF THE SYNOPTIC MODELS SHOW THE STRONG
UPPER LEVEL LOW PRESSURE SYSTEM MOVING ACROSS OR NEAR THE FOUR
CORNERS AREA ON SATURDAY...SETTING UP A SNOW PATTERN FOR NORTHEAST
COLORADO. HOWEVER...AGREEMENT BETWEEN THE MODELS IS FAR FROM
UNANIMOUS. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF AND THE NAM
ONLY GOES OUT TO MIDDAY SATURDAY BUT SHOWS AGREEMENT WITH THE GFS.
PRECIPITATION AMOUNTS ALSO VARY BETWEEN THE DIFFERENT MODELS. THE
NAM SHOWS AN INITIALLY DRY SWATH OF AIR MOVING ACROSS THE EASTERN
PLAINS WITH THE EJECTING UPPER LOW...WHILE THE GFS GENERATES
COPIOUS AMOUNTS OF SNOWFALL. THE ECMWF SHOWS ONLY LIGHT TO
MODERATE SNOW AMOUNTS THROUGH SATURDAY NIGHT. NEEDLESS TO
SAY...MANY QUESTIONS STILL REMAIN ON HOW BIG THIS STORM IS GOING
TO BE. THE STORM SYSTEM...WHICH IS CURRENTLY DEVELOPING OFF THE
COAST OF OREGON IS GOING TO CONTAIN A LOT OF COLD AIR ALOFT AND
WILL ALSO ENCOUNTER A GOOD SHOT OF LOW LEVEL MOISTURE FROM THE
GULF OF MEXICO WHEN IT MOVES ACROSS COLORADO. MODEL SOUNDINGS SHOW
LAPSE RATES SATURDAY AFTERNOON WILL BE NEARLY MOIST ADIABATIC DUE
TO THE COLD TEMPERATURES ALOFT. IF THE SYSTEM TAKES ITS TIME
MOVING ACROSS COLORADO...SIMILAR TO THE ECMWF SOLUTION...THEN IT
WILL BE ABLE TO PRODUCE SNOW AMOUNTS HEAVIER THAN WHAT THE ECMWF
CONTAINS. THE TIMING OF THE GFS AND NAM SOLUTIONS MAY WELL END UP
BEING TOO FAST AS THE SYSTEM ALREADY LOOKS LIKE IT IS READY TO
CUTOFF FROM THE NORTHERN STREAM IN THE NEXT 24 TO 36 HOURS. GIVEN
ALL THE UNCERATINTY...IT IS TOO EARLY TO ISSUE ANY HIGHLIGHTS...
BUT THAT MAY CHANGE LATER TODAY OR TONIGHT. ALONG WITH THE UPPER
DYNAMICS OF THE PASSING UPPER LOW ON SATURDAY...IT LOOKS LIKE A
STRONG SURGE OF NORTHERLY SURFACE WINDS WILL DEVELOP SATURDAY
AFTERNOON ON THE BACK SIDE OF THE STORM. HAVE ADDED AREAS OF
BLOWING SNOW TO THE SATURDAY AFTERNOON AND EVENING FORECAST.
FOR SUNDAY THROUGH TUESDAY...MODELS SHOW COLORADO UNDER NORTHWEST
FLOW WITH WARMER TEMPERATURES AND DRIER CONDITIONS. TEMPERATURE
FORECASTS FOR THESE DAYS IS GOING TO BE VERY DEPENDENT ON HOW MUCH
SNOW FALLS DURING THE SATURDAY THROUGH SUNDAY PERIOD. FOR THE TIME
BEING...WILL KEEP THIS PART OF THE FORECAST VERY GENERAL.
AVIATION...VFR THRU TONIGHT. WK SFC LOW PRES WILL LIKELY REMAIN
WEST OF THE AIRPORT THRU THIS AFTN. OVERALL THE HRRR AND RAP
KEEP WINDS LIGHT SSW THRU LATE MORNING AND THEN GRADUALLY SHIFTTHEN
MORE ELY BY EARLY AFTN. THE ELY WINDS ARE FCST TO STAY IN PLACE AT
LEAST THRU 23Z BEFORE BECOMING MORE SELY BY 01Z. WINDS WILL THEN
GRADUALLY BECOME DRAINAGE BY 03Z AND CONTINUE THAT WAY OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RTG
LONG TERM....99
AVIATION...RTG
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1000 AM MST WED MAR 6 2013
.UPDATE...WILL CLOSELY WATCH MIXING TODAY...MID SHIFT DID
DELINIATE FOR SNOW ON GROUND WITH COOLER MAXES FROM SOUTHERN WELD
TO NORTHEASTERN ELBERT COUNTIES. THERE IS ALSO SOME CLOUDS TO
ACCOUNT FOR IN THESE AREAS. OTHERWISE NO CHANGES EXPECTED.
&&
.AVIATION...A BIT OF HAZE AT KDIA WILL DISSIPATE WITH MIXING
TODAY...SO LOOKING FOR DRY VFR CONDITIONS WITH LIGHT WINDS.
&&
.PREV DISCUSSION... /ISSUED 408 AM MST WED MAR 6 2013/
SHORT TERM...SWLY FLOW ALOFT WILL DEVELOP OVER THE AREA AS THE
UPPER LEVEL RIDGE SHIFTS EAST. SOME HIGHER LEVEL CLOUDS WILL BE
POSSIBLE OTHERWISE IT WILL REMAIN DRY THRU TONIGHT. ONCE AGAIN
HIGH TEMPS THIS AFTN WILL BE THE MAIN ISSUE. SOME DEEPER SNOW
COVER STILL RESIDES OVER SRN WELD...CNTRL AND ERN PORTIONS OF ADAMS
AND ARAPAHOE ALONG WITH ELBERT COUNTIES WHICH WILL AFFECT AFTN
HIGHS IN THESE AREAS AS READINGS MAY NOT GET OUT OF THE 40S.
MEANWHILE NR THE FOOTHILLS LIGHT WLY DOWNSLOPE FLOW WILL DVLP
WHICH MAY ALLOW FOR HIGHS TO REACH THE LOWER 60S OVER THE WRN AND
SRN SUBURBS OF DENVER. THUS WILL SEE QUITE A TEMP DIFFERENCE ALONG
THE FRONT RANGE THIS AFTN. OVER THE PLAINS WHERE NO SNOW COVER
EXISTS WINDS WILL BE MAINLY SELY SO WILL KEEP AFTN HIGHS IN THE
LOWER TO MID 50S EXCEPT OVER SRN LINCOLN COUNTY WHERE LOWER 60S
WILL BE POSSIBLE DUE TO SWLY LOW LVL WINDS. FOR TONIGHT MAY SEE
SOME PATCHY FOG DVLP OVER THE FAR NERN PLAINS AFTER MIDNIGHT.
LONG TERM...THURSDAY WILL BE DRY AND WARM AS SOUTHWESTERLY FLOW
ALOFT COVERS THE STATE. FRIDAY WILL BE A TRANSITIONAL DAY AS
SOUTHWEST FLOW ALOFT CONTINUES BUT MOISTURE BEGINS INCREASING
AHEAD OF A POTENT UPPER LOW MOVING OVER THE DESERT SOUTHWEST. AND
SATURDAY LOOKS LIKE IT WILL BE THE MOST CRITICAL DAY OF THIS
FORECAST PACKAGE. EACH OF THE SYNOPTIC MODELS SHOW THE STRONG
UPPER LEVEL LOW PRESSURE SYSTEM MOVING ACROSS OR NEAR THE FOUR
CORNERS AREA ON SATURDAY...SETTING UP A SNOW PATTERN FOR NORTHEAST
COLORADO. HOWEVER...AGREEMENT BETWEEN THE MODELS IS FAR FROM
UNANIMOUS. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF AND THE NAM
ONLY GOES OUT TO MIDDAY SATURDAY BUT SHOWS AGREEMENT WITH THE GFS.
PRECIPITATION AMOUNTS ALSO VARY BETWEEN THE DIFFERENT MODELS. THE
NAM SHOWS AN INITIALLY DRY SWATH OF AIR MOVING ACROSS THE EASTERN
PLAINS WITH THE EJECTING UPPER LOW...WHILE THE GFS GENERATES
COPIOUS AMOUNTS OF SNOWFALL. THE ECMWF SHOWS ONLY LIGHT TO
MODERATE SNOW AMOUNTS THROUGH SATURDAY NIGHT. NEEDLESS TO
SAY...MANY QUESTIONS STILL REMAIN ON HOW BIG THIS STORM IS GOING
TO BE. THE STORM SYSTEM...WHICH IS CURRENTLY DEVELOPING OFF THE
COAST OF OREGON IS GOING TO CONTAIN A LOT OF COLD AIR ALOFT AND
WILL ALSO ENCOUNTER A GOOD SHOT OF LOW LEVEL MOISTURE FROM THE
GULF OF MEXICO WHEN IT MOVES ACROSS COLORADO. MODEL SOUNDINGS SHOW
LAPSE RATES SATURDAY AFTERNOON WILL BE NEARLY MOIST ADIABATIC DUE
TO THE COLD TEMPERATURES ALOFT. IF THE SYSTEM TAKES ITS TIME
MOVING ACROSS COLORADO...SIMILAR TO THE ECMWF SOLUTION...THEN IT
WILL BE ABLE TO PRODUCE SNOW AMOUNTS HEAVIER THAN WHAT THE ECMWF
CONTAINS. THE TIMING OF THE GFS AND NAM SOLUTIONS MAY WELL END UP
BEING TOO FAST AS THE SYSTEM ALREADY LOOKS LIKE IT IS READY TO
CUTOFF FROM THE NORTHERN STREAM IN THE NEXT 24 TO 36 HOURS. GIVEN
ALL THE UNCERATINTY...IT IS TOO EARLY TO ISSUE ANY HIGHLIGHTS...
BUT THAT MAY CHANGE LATER TODAY OR TONIGHT. ALONG WITH THE UPPER
DYNAMICS OF THE PASSING UPPER LOW ON SATURDAY...IT LOOKS LIKE A
STRONG SURGE OF NORTHERLY SURFACE WINDS WILL DEVELOP SATURDAY
AFTERNOON ON THE BACK SIDE OF THE STORM. HAVE ADDED AREAS OF
BLOWING SNOW TO THE SATURDAY AFTERNOON AND EVENING FORECAST.
FOR SUNDAY THROUGH TUESDAY...MODELS SHOW COLORADO UNDER NORTHWEST
FLOW WITH WARMER TEMPERATURES AND DRIER CONDITIONS. TEMPERATURE
FORECASTS FOR THESE DAYS IS GOING TO BE VERY DEPENDENT ON HOW MUCH
SNOW FALLS DURING THE SATURDAY THROUGH SUNDAY PERIOD. FOR THE TIME
BEING...WILL KEEP THIS PART OF THE FORECAST VERY GENERAL.
AVIATION...VFR THRU TONIGHT. WK SFC LOW PRES WILL LIKELY REMAIN
WEST OF THE AIRPORT THRU THIS AFTN. OVERALL THE HRRR AND RAP
KEEP WINDS LIGHT SSW THRU LATE MORNING AND THEN GRADUALLY SHIFTTHEN
MORE ELY BY EARLY AFTN. THE ELY WINDS ARE FCST TO STAY IN PLACE AT
LEAST THRU 23Z BEFORE BECOMING MORE SELY BY 01Z. WINDS WILL THEN
GRADUALLY BECOME DRAINAGE BY 03Z AND CONTINUE THAT WAY OVERNIGHT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RTG
LONG TERM....99
AVIATION...RTG
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
249 PM EST WED MAR 6 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 350 AM EST WED MAR 6 2013
STRONG LOW PRESSURE OVER SOUTHEAST OHIO WILL MOVE ON TO THE EAST
COAST AS UPPER DISTURBANCE MOVES SOUTHEAST ACROSS THE GREAT LAKES.
OVER THE NEXT FEW DAYS MODELS MOVE AN AREA OF HIGH PRESSURE EAST
INTO OUR REGION AND AN UPPER RIDGE OF HIGH PRESSURE OVER THE ROCKIES
WILL MOVE OUR WAY BY SATURDAY.
IN THE EXTENDED..AN AREA OF LOW PRESSURE WILL MOVE OUR WAY LATE
SUNDAY AND MONDAY. TEMPERATURES WILL BE QUITE MILD THIS
WEEKEND...BUT WILL COOL OFF SOME MONDAY AND TUESDAY AFTER A COLD
FRONT MOVES THROUGH.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1006 AM EST WED MAR 6 2013
RADAR LOOP SHOWED SNOW SHOWERS HAD MOVED OUT OF THE AREA EARLIER
THIS MORNING SO WINTER WEATHER ADVISORY WAS ALLOWED TO EXPIRE AT 9
AM. SATELLITE PICTURE SHOWS CLOUDY SKIES ACROSS ALL OF CENTRAL
INDIANA AND THIS TREND SHOULD CONTINUE THROUGH THE DAY...WITH
PERHAPS MOSTLY CLOUDY BY LATE THIS EVENING. WING GUSTS OF 20 TO 30
MPH CONTINUE ACROSS THE AREA BUT SHOULD LESSEN GRADUALLY
THROUGHOUT THE DAY. FORECAST SOUNDINGS IN BOTH THE NAM AND THE RAP FOR
THIS AFTERNOON SHOW SOME SHALLOW INSTABILITY AND RECENTLY THIS HAS
BEEN A PRETTY GOOD INDICATOR OF LIGHT SNOW SHOWER DEVELOPMENT.
WITH LITTLE IN THE WAY OF FORCING ON THE BACK SIDE OF THIS LOW HAVE
OPTED AGAINST ADDING ANYTHING MEASURABLE BUT HAVE ADDED A CHANCE
FOR FLURRIES FOR THE AFTERNOON. GOING HIGH TEMPERATURES IN THE 30S
LOOK GOOD WITH THE CLOUD COVER AND NORTHWEST FLOW.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 350 AM EST WED MAR 6 2013
FORECAST FOCUS WILL BE ON SKY COVER AND TEMPERATURES AS MUCH QUIETER
WEATHER WILL BE THE RULE. HIGH PRESSURE RIDGE DRIFTS ACROSS THE
PLAINS WILL BUILD EAST ACROSS OUR REGION FRIDAY. WITH
SUBSIDENCE...CLOUDS WILL GRADUALLY DECREASE LATER TONIGHT AND
THURSDAY. MODELS MOVE AN UPPER DISTURBANCE ACROSS SOUTHEAST ACROSS
THE EASTERN GREAT LAKES AND EASTERN OHIO LATER TONIGHT AND THURSDAY.
WILL KEEP MORE CLOUDS ACROSS OUR NORTH AND EAST THROUGH THURSDAY.
OTHERWISE...MOST AREAS WILL BECOME MOSTLY CLEAR THURSDAY NIGHT AND
REMAIN THAT WAY UNTIL SATURDAY MORNING.
WILL LEAN TOWARDS THE COOLER END OF MOS TEMPERATURES THROUGH
THURSDAY NIGHT AS THERE WILL BE SOME SNOW COVER ESPECIALLY EAST.
WITH CLEAR SKIES AND LIGHT WINDS WILL UNDERCUT MOS TEMPERATURES 4 TO
6 DEGREES THURSDAY NIGHT. BY FRIDAY THE SNOW COVER SHOULD BE MOSTLY
GONE AND WILL WITH THE POSSIBLE EXCEPTION OUR FAR EAST. WILL GO
CLOSE TO A MOS BLEND ON TEMPERATURES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
ISSUED AT 249 PM EST WED MAR 6 2013
ACTIVE PATTERN RETURNS THROUGH THE PERIOD. AN UPPER LEVEL TROUGH
WILL EJECT OUT OF THE ROCKIES SATURDAY NIGHT AND INDUCE A SURFACE
LOW THAT WILL TRACK ACROSS THE CENTRAL PLAINS ON SUNDAY. EXTENDED
MODEL GUIDANCE IN DECENT AGREEMENT ON KEEPING THE UPPER LEVEL WAVE
FAIRLY PROGRESSIVE AS RIDGING ALOFT AHEAD OF THE SYSTEM BREAKS
DOWN BY EARLY MONDAY. NICE SURGE OF WARM GULF AIR AHEAD OF THE
SYSTEM WILL TRANSPORT PLENTY OF MOISTURE INTO THE OHIO VALLEY WITH
PRECIP WATER VALUES CLIMBING TO AN INCH OR BETTER BY SUNDAY NIGHT
AND MONDAY. ANY LINGERING PILES OF SNOW THAT STILL REMAIN BY THE
WEEKEND WILL LIKELY BE WIPED OUT AS EXPECT WIDESPREAD RAINFALL TO
ACCOMPANY THE LOW PRESSURE AND FRONTAL BOUNDARY. WILL CARRY LIKELY
POPS SUNDAY NIGHT AND MONDAY AS THE LOW PASSES THROUGH THE OHIO
VALLEY.
HIGHS MAINLY IN THE 50S SUNDAY AND UPPER 40S/LOWER 50S MONDAY WILL
FALL BACK INTO THE 40S FOR TUESDAY AND WEDNESDAY AS COLDER AIR
RETURNS IN THE WAKE OF THE FRONTAL PASSAGE. COLDEST TEMPERATURES
THROUGHOUT THE EXTENDED LIKELY TO BE WEDNESDAY AS AN UPPER LEVEL
TROUGH CARVES OUT ACROSS THE GREAT LAKES. MAY SEE LIGHT SNOW MIX
IN WITH RAIN AS PRECIP DIMINISHES MONDAY NIGHT INTO TUESDAY...WITH
DRIER WEATHER RESUMING FOR MIDWEEK.
&&
.AVIATION /DISCUSSION FOR 061800Z TAF ISSUANCE/...
ISSUED AT 1222 PM EST WED MAR 6 2013
MVFR CEILINGS TO PERSIST THROUGHOUT THE FORECAST PERIOD.
CENTRAL INDIANA REMAINS IN A COLD CYCLONIC FLOW IN THE WAKE OF THE
STORM THAT IMPACTED THE REGION LAST NIGHT AND EARLY THIS MORNING.
EXTENSIVE STRATUS DECK ENCOMPASSING THE GREAT LAKES AND OHIO
VALLEY...WITH CEILINGS GENERALLY BETWEEN 1000-1500FT. EXPECT THICK
STRATUS DECK TO REMAIN FOR THE REST OF THE DAY AND OVERNIGHT...
POSSIBLY LIFTING TOWARDS 2000FT THROUGH THIS EVENING BEFORE
FALLING BACK TONIGHT WITH THE INVERSION HOLDING. VERY WEAK SHALLOW
INSTABILITY PRESENT THROUGH THE AFTERNOON COULD GENERATE A FEW
FLURRIES WITH NO IMPACT TO TERMINALS. NORTHWEST WINDS AT 10-15KTS
THIS AFTERNOON WILL DIMINISH TO AROUND 5KTS TONIGHT.
INCREASINGLY DRIER AIR BUILDING INTO THE REGION THURSDAY WITH HIGH
PRESSURE...BUT MODEL SOUNDINGS INDICATING LOWER CLOUDS WILL LIKELY
BE SLOW TO BUDGE. WILL RAISE CEILINGS TO 2KFT THURSDAY MORNING
WITH MORE SUBSTANTIAL CLEARING LIKELY TO HOLD OFF UNTIL LATER ON
THURSDAY. LIGHT NORTHERLY FLOW IS EXPECTED THURSDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...CP
SHORT TERM...JH
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1222 PM EST WED MAR 6 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 350 AM EST WED MAR 6 2013
STRONG LOW PRESSURE OVER SOUTHEAST OHIO WILL MOVE ON TO THE EAST
COAST AS UPPER DISTURBANCE MOVES SOUTHEAST ACROSS THE GREAT LAKES.
OVER THE NEXT FEW DAYS MODELS MOVE AN AREA OF HIGH PRESSURE EAST
INTO OUR REGION AND AN UPPER RIDGE OF HIGH PRESSURE OVER THE ROCKIES
WILL MOVE OUR WAY BY SATURDAY.
IN THE EXTENDED..AN AREA OF LOW PRESSURE WILL MOVE OUR WAY LATE
SUNDAY AND MONDAY. TEMPERATURES WILL BE QUITE MILD THIS
WEEKEND...BUT WILL COOL OFF SOME MONDAY AND TUESDAY AFTER A COLD
FRONT MOVES THROUGH.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1006 AM EST WED MAR 6 2013
RADAR LOOP SHOWED SNOW SHOWERS HAD MOVED OUT OF THE AREA EARLIER
THIS MORNING SO WINTER WEATHER ADVISORY WAS ALLOWED TO EXPIRE AT 9
AM. SATELLITE PICTURE SHOWS CLOUDY SKIES ACROSS ALL OF CENTRAL
INDIANA AND THIS TREND SHOULD CONTINUE THROUGH THE DAY...WITH
PERHAPS MOSTLY CLOUDY BY LATE THIS EVENING. WING GUSTS OF 20 TO 30
MPH CONTINUE ACROSS THE AREA BUT SHOULD LESSEN GRADUALLY
THROUGHOUT THE DAY. FORECAST SOUNDINGS IN BOTH THE NAM AND THE RAP FOR
THIS AFTERNOON SHOW SOME SHALLOW INSTABILITY AND RECENTLY THIS HAS
BEEN A PRETTY GOOD INDICATOR OF LIGHT SNOW SHOWER DEVELOPMENT.
WITH LITTLE IN THE WAY OF FORCING ON THE BACK SIDE OF THIS LOW HAVE
OPTED AGAINST ADDING ANYTHING MEASURABLE BUT HAVE ADDED A CHANCE
FOR FLURRIES FOR THE AFTERNOON. GOING HIGH TEMPERATURES IN THE 30S
LOOK GOOD WITH THE CLOUD COVER AND NORTHWEST FLOW.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 350 AM EST WED MAR 6 2013
FORECAST FOCUS WILL BE ON SKY COVER AND TEMPERATURES AS MUCH QUIETER
WEATHER WILL BE THE RULE. HIGH PRESSURE RIDGE DRIFTS ACROSS THE
PLAINS WILL BUILD EAST ACROSS OUR REGION FRIDAY. WITH
SUBSIDENCE...CLOUDS WILL GRADUALLY DECREASE LATER TONIGHT AND
THURSDAY. MODELS MOVE AN UPPER DISTURBANCE ACROSS SOUTHEAST ACROSS
THE EASTERN GREAT LAKES AND EASTERN OHIO LATER TONIGHT AND THURSDAY.
WILL KEEP MORE CLOUDS ACROSS OUR NORTH AND EAST THROUGH THURSDAY.
OTHERWISE...MOST AREAS WILL BECOME MOSTLY CLEAR THURSDAY NIGHT AND
REMAIN THAT WAY UNTIL SATURDAY MORNING.
WILL LEAN TOWARDS THE COOLER END OF MOS TEMPERATURES THROUGH
THURSDAY NIGHT AS THERE WILL BE SOME SNOW COVER ESPECIALLY EAST.
WITH CLEAR SKIES AND LIGHT WINDS WILL UNDERCUT MOS TEMPERATURES 4 TO
6 DEGREES THURSDAY NIGHT. BY FRIDAY THE SNOW COVER SHOULD BE MOSTLY
GONE AND WILL WITH THE POSSIBLE EXCEPTION OUR FAR EAST. WILL GO
CLOSE TO A MOS BLEND ON TEMPERATURES.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 336 PM EST TUE MAR 5 2013
AN UPPER RIDGE WILL BUILD OVER THE REGION LATE IN THE WORK WEEK AND
MOVES EAST CROSS THE REGION THROUGH THE WEEKEND. DRY WEATHER AND
WARMER TEMPERATURES WILL ENSUE ACROSS THE AREA. BY SUNDAY A BROAD
UPPER TROUGH WILL APPROACH THE REGION. A DISTURBANCE OUT OF AHEAD OF
THIS SYSTEM WILL MOVE ACROSS THE AREA SUNDAY...WITH THE STRONG UPPER
LOW TO CROSS THE REGION MONDAY AND TUESDAY. SLIGHT CHANCE FOR RAIN
WILL BE IN THE FORECAST FOR SUNDAY WITH HIGHER CHANCES FROM MONDAY
INTO TUESDAY AS THE CENTER OF THE UPPER LOW MOVES ACROSS THE GREAT
LAKES. ALL BLEND TEMPERATURES SEEM REASONABLE GIVEN MODEL CONSENSUS
AND DID NOT MAKE ANY SIGNIFICANT CHANGES TO THEIR NUMBERS.
&&
.AVIATION /DISCUSSION FOR 061800Z TAF ISSUANCE/...
ISSUED AT 1222 PM EST WED MAR 6 2013
MVFR CEILINGS TO PERSIST THROUGHOUT THE FORECAST PERIOD.
CENTRAL INDIANA REMAINS IN A COLD CYCLONIC FLOW IN THE WAKE OF THE
STORM THAT IMPACTED THE REGION LAST NIGHT AND EARLY THIS MORNING.
EXTENSIVE STRATUS DECK ENCOMPASSING THE GREAT LAKES AND OHIO
VALLEY...WITH CEILINGS GENERALLY BETWEEN 1000-1500FT. EXPECT THICK
STRATUS DECK TO REMAIN FOR THE REST OF THE DAY AND OVERNIGHT...
POSSIBLY LIFTING TOWARDS 2000FT THROUGH THIS EVENING BEFORE
FALLING BACK TONIGHT WITH THE INVERSION HOLDING. VERY WEAK SHALLOW
INSTABILITY PRESENT THROUGH THE AFTERNOON COULD GENERATE A FEW
FLURRIES WITH NO IMPACT TO TERMINALS. NORTHWEST WINDS AT 10-15KTS
THIS AFTERNOON WILL DIMINISH TO AROUND 5KTS TONIGHT.
INCREASINGLY DRIER AIR BUILDING INTO THE REGION THURSDAY WITH HIGH
PRESSURE...BUT MODEL SOUNDINGS INDICATING LOWER CLOUDS WILL LIKELY
BE SLOW TO BUDGE. WILL RAISE CEILINGS TO 2KFT THURSDAY MORNING
WITH MORE SUBSTANTIAL CLEARING LIKELY TO HOLD OFF UNTIL LATER ON
THURSDAY. LIGHT NORTHERLY FLOW IS EXPECTED THURSDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...CP
SHORT TERM...JH
LONG TERM....NIELD
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
340 PM CST WED MAR 6 2013
.SYNOPSIS...
ISSUED AT 332 PM CST WED MAR 6 2013
12Z UA ANALYSIS HAS A STRONG EXTRATROPICAL CYCLONE OVER THE MID
ATLANTIC STATES WITH A RIDGE OVER THE PLAINS. SATELLITE TRENDS
THROUGH MID AFTERNOON SHOW GRADUAL CLEARING AS THE STRONGER MARCH
ALLOWS BREAKS TO DEVELOP IN THE MOISTURE LAYER TRAPPED UNDER THE
INVERSION.
18Z SFC ANALYSIS HAS A RIDGE THROUGH THE PLAINS WITH AN INVERTED
TROF RUNNING FROM THE OHIO VALLEY INTO UPPER MICHIGAN. DEW POINTS
WERE IN THE TEENS AND 20S ACROSS THE MIDWEST.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 332 PM CST WED MAR 6 2013
NOT ONE MODEL IS HANDLING THE THIN MOISTURE LAYER TRAPPED UNDER
THE INVERSION. THE RAP 0.5 KM RH/CONDENSATION PRESSURE/WIND HAS A
LOOSE CORRELATION ON WHAT IS CURRENTLY HAPPENING.
TAKING INPUTS FROM THE RAP TRENDS AND COMBINING THEM WITH SATELLITE
TRENDS INDICATES CLEARING WILL OCCUR ACROSS THE WESTERN THIRD OF THE
CWFA LATE THIS AFTERNOON WITH IT PROGRESSING EAST TO THE MISSISSIPPI
BY SUNSET. AFTER SUNSET THE QUESTION THEN BECOMES WILL THE CLEARING
TREND CONTINUE OR STOP. THE RAP SUGGESTS THE CLEARING WOULD STOP
WITH CLOUDS REMAINING TRAPPED UNDER THE INVERSION. OTHER DATA
SUGGEST THE CLEARING TREND WOULD CONTINUE BUT SLOW DOWN.
SO...HAVE OPTED TO GO WITH THE IDEA OF SLOWING DOWN THE CLEARING
TREND THIS EVENING WITH THE FAR EAST CLEARING AFTER MIDNIGHT.
MOISTURE IN THE LOW LEVELS IS NOT REALLY BEING SCOURED OUT SO THOSE
AREAS THAT CLEAR BY SUNSET WILL HAVE A FOG THREAT AS THE HIGH
SETTLES ACROSS THE AREA.
GOING ON THE ASSUMPTION THAT FOG WILL DEVELOP IN THE CLEAR SKIES AND
LIGHT WINDS OVER THE SNOW PACK...AREAS ROUGHLY ALONG AND WEST OF THE
MISSISSIPPI WOULD BE MOST AT RISK STARTING TOWARD MIDNIGHT AND
CONTINUING INTO THURSDAY MORNING. THE EASTERN 40 PERCENT OF THE CWFA
MAY SEE SOME PATCHY FOG DEVELOP AROUND SUNRISE.
VERY LITTLE FOG DEVELOPED UNDER THE SFC RIDGE LAST NIGHT DUE TO
CLOUD COVER. SO IT IS NOT KNOWN IF HEADLINES WOULD BE NEEDED FOR ANY
FOG THAT DEVELOPS TONIGHT. TRENDS WILL NEED TO BE MONITORED DURING
THE EVENING FOR THIS POSSIBLE THREAT.
IF FOG DEVELOPS TONIGHT AND BECOMES SUFFICIENTLY THICK...THEN RIME
DEPOSITS COULD DEVELOP ON SOME ROADS AND POSSIBLY RESULT IN SLICK
SPOTS DEVELOPING.
THURSDAY LOOKS TO BE QUIET AND DRY WITH SUNSHINE AS THE HIGH SLOWLY
MOVES TOWARD MICHIGAN AND INDIANA.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 332 PM CST WED MAR 6 2013
MAIN FOCUS WITH STORM SYSTEM OVER THE WEEKEND INTO VERY EARLY NEXT
WEEK AND PCPN CHCS/TYPE/AMOUNTS.
LARGE CUTOFF LOW CHURNING JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS AFTERNOON IS SHOWN BY MODELS TO DIG INTO THE
SOUTHWESTERN CONUS BY LATE WEEK BEFORE EJECTING OUT FROM THE
ROCKIES THROUGH THE MID-MISSISSIPPI VALLEY OVER THE WEEKEND INTO
EARLY NEXT WEEK. MODELS GENERALLY SHOW THE LOW OPENING UP AND
EJECTING OUT AS POSITIVE TILTED TROUGH AS SUGGESTION OF SOME PHASING
WITH CANADIAN PLAINS SHORTWAVE ENERGY. THE UNCERTAINTIES MOSTLY
PERTAIN TO THE TRACK...AND ALSO STRENGTH/TIMING OF SYSTEM
WEAKENING OR OPENING UP BOTH OF WHICH LIKELY IMPACTED BY THE AMOUNT
OF INTERACTION WITH CANADIAN ENERGY. THE UNCERTAINTIES WITH TRACK
AND STRENGTH OF SYSTEM TO HAVE IMPACT ON TEMPS AND PRECIPITATION TYPE
AND AMOUNTS...AND WHETHER OR NOT WILL SEE A DEFORMATION ZONE. THIS
WILL PROBABLY TO TAKE AT LEAST ANOTHER 24+ HRS TO RESOLVE AS THE
CANADIAN ENERGY MOSTLY IN QUESTION IS STILL WELL OUT IN THE PACIFIC
JUST SOUTH OF THE ALEUTIAN ISLANDS.
THU NGT-FRIDAY NGT... MAINLY DRY AS HIGH PRESSURE IN CONTROL FOR MUCH
OF THE PERIOD. FAVORED NEAR THE COLD SIDE OF GUIDANCE OR JUST BELOW
ON TEMPS AS PAST EXPERIENCE WITH DRY LOW LEVEL E/SE FLOW ON BACKSIDE
OF DEPARTING HIGH NOT CONDUCIVE FOR A LOT OF WARMING... ESPECIALLY WITH
SNOW COVER. LOW LEVEL JET AND ATTENDANT STRONG MOISTURE TRANSPORT TO
FUEL DEVELOPMENT OF PCPN TO OUR WEST BY FRIDAY EVENING AND MAY SEE
SOME STRATIFYING LIGHT PCPN MOVE INTO WESTERN SECTIONS LATE FRIDAY NGT
WITH VEERING/WEAKENING LOW LEVEL JET WELL NORTH OF DEVELOPING SFC WARM
FRONT. COLD DRY FETCH FROM DEPARTING HIGH AND EVAPORATIONAL COOLING
SUPPORT RISK OF SOME FREEZING RAIN WITH INITIAL ONSET OF PCPN
BEFORE SATURATION AND CONTINUED WARM... MOIST ADVECTION ABATES RISK
SATURDAY AM.
SAT-SUN... RAIN EXPECTED TO EVENTUALLY OVERSPREAD CWA SAT-SAT NGT AND
LINGER THROUGH SUNDAY WITH STRONG MOISTURE TRANSPORT AND INCREASINGLY
DIFFLUENT FLOW ALOFT. SFC DEWPTS WELL INTO THE 40S AND 850 MB DEWPTS
OF 5-7C COMBINED WITH MAGNITUDE OF FORCING SUPPORTIVE OF WIDESPREAD
MODERATE TO HEAVY RAIN AMOUNTS 0.25 TO 1 INCH... WITH LOCALLY
HIGHER AMOUNTS 1-2 INCHES WITH SOME CONVECTION. THIS RAISES CONCERNS
ON FLOODING WITH POTENTIAL FOR RAPID SNOWMELT OCCURRING ALONGSIDE THE
MODERATE TO HEAVY RAINS GIVEN AREA STREAMS AND RIVERS NEAR TO ABOVE
NORMAL IN MANY LOCATIONS... WHILE FROST DEPTH DOWN TO 8 INCHES ALTHOUGH
SOME THAW IN TOP PORTIONS BUT SATURATED... OVERALL SUPPORTIVE OF RUN-OFF
INCREASING RISK FOR SOME LOW END FLOODING. CONTINUED TO UNCERCUT
GUIDANCE ON TEMPS SAT AND EXPECT READINGS STEADY TO SLOWLY RISING SAT
NGT THROUGH SUNDAY IF TRACK REMAINS UNCHANGED NEAR TO OVER THE
CWA. WITH DEWPTS WELL IN THE 40S TO POSSIBLY EVEN LOWER 50S SAT NGT
INTO SUNDAY WOULD EXPECT SOME GOOD ADVECTION FOG OVER THE COLDER SNOW
COVERED GROUND... WHICH COULD BE QUITE DENSE.
MON-WED... RISK OF RAIN CHANGING TO SNOW SUNDAY NGT LINGERING MON
ESPECIALLY WITH DEFORMATION ZONE IF SYSTEM SLOWER TO WEAKEN... AND WILL
HAVE TO WATCH SUN NGT INTO MON ONCE AGAIN FOR SOME ACCUMULATING
SNOW POTENTIAL. OTHERWISE... MAINLY BELOW NORMAL TEMPS MON-WED WITH
SOME SUGGESTION OF CLIPPER SYSTEM AND CHC OF LIGHT SNOW SOMETIME IN
TUE-WED TIMEFRAME... BUT THIS ALL DEPENDENT ON EVOLUTION AND TIMING OF
THE WEEKEND SYSTEM AND THUS FOR NOW HAVE NO MENTION.
BEYOND FOR 7-10+ DAYS ... STRONG INDICATION OF CONTINUED BELOW NORMAL
TEMPS WITH PERIODIC CLIPPER SYSTEMS IN GENERALLY NORTHWEST FLOW ALOFT.
05
&&
.AVIATION...
ISSUED AT 332 PM CST WED MAR 6 2013
SATELLITE TRENDS THROUGH 20Z/06 ARE NOW POINTING TO CLEARING
DVLPG AT KCID PRIOR TO SUNSET AND POTENTIALLY AT KDBQ/KMLI/BRL
AROUND OR SHORTLY AFT SUNSET. THUS CONDITIONS ARE EXPECTED TO
IMPROVE TO VFR. LIGHT WINDS OVER THE SNOW FIELD AND CLEAR SKIES
BRINGS THE THREAT OF FG DEVELOPING. IF FG DEVELOPS AFT
SUNSET...THE POTENTIAL EXISTS FOR LIFR CONDITIONS DVLPG AFT
06Z/07. 08
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1130 AM CST WED MAR 6 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
MAIN FORECAST CONCERN TODAY IS LINGERING
STRATUS DECK AND WHETHER IT WILL DISSIPATE DURING THE AFTERNOON.
SURFACE HIGH AND UPPER LEVEL RIDGE BUILD INTO THE STATE PAST 18Z
TODAY AND BRING LIGHT FLOW TO THE FORECAST AREA. INVERSION
STRENGTHENS AS DRIER AIR FILTER WITH THE UPPER RIDGE MOVING INTO THE
STATE THIS AFTERNOON. STRATUS DECK EXTENDS UP INTO CANADA AND THE
GENERALLY NORTH FLOW CONTINUES THROUGH AT LEAST MIDDAY BEFORE WINDS
BECOME LIGHT AND VARIABLE. LOW CONFIDENCE WITH STRATUS DISSIPATING
BEFORE 18Z AND EVEN AT ALL THROUGH THE AFTERNOON. VERY MINIMAL
MIXING AND IF STRATUS DECK REMAINS IN PLACE WHEN SURFACE HIGH SLIDES
OVER CENTRAL IOWA...THINKING IT WILL BECOME TRAPPED UNDERNEATH THE
INVERSION INTO THIS EVENING OR POSSIBLY TOMORROW BEFORE THE WAA
DEVELOPS ON THE BACKSIDE OF THE SURFACE HIGH. AS A
RESULT...INCREASED SKY COVER THROUGH THE AFTERNOON WITH IT SLOWLY
DISSIPATING PAST 21Z. THE 05Z HRRR KEEPS THE STRATUS GOING THROUGH
THE AFTERNOON EXCEPT THE FAR SOUTHWEST. WRT TO TEMPS TODAY...LEANED
TOWARD THE NAM FOR MAX TEMPS TODAY AS IT SEEMS TO HAVE A GOOD HANDLE
ON THE STRATUS AS WELL.
.LONG TERM /TONIGHT THROUGH TUESDAY/...
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS IOWA TONIGHT. STILL
UNCERTAIN HOW WIDESPREAD THE STRATUS WILL BE OVERNIGHT. THE
STRATUS WILL BE TOUGH TO GET RID OF OVERNIGHT IF IT SURVIVES TODAY
WITH VERY LITTLE SUBSIDENCE OR STEERING FLOW IN PLACE. THE
UNCERTAINTY WITH THE STRATUS LEAVES A WIDE RANGE IN POSSIBLE LOW
TEMPERATURES OVERNIGHT. TEMPERATURES WILL DROP WELL INTO THE
SINGLE DIGITS OVERNIGHT ACROSS THE NORTHEAST WITH CLEARING BUT
WOULD REMAIN IN THE MID TO UPPER TEENS IF CLOUDS PERSIST. HAVE
LEANED TOWARDS CLEARING OR PARTIAL CLEARING AND COLDER
TEMPERATURES AT THIS TIME. THE HIGH PRESSURE RIDGE SHIFTS EAST ON
THURSDAY WITH RETURN FLOW DEVELOPING IN ADDITION TO A TRANSITION
TO MID LEVEL RIDGING. THIS WILL CONTINUE INTO FRIDAY WITH EVEN
WARMER TEMPERATURES EXPECTED IN THE UPPER 30S TO UPPER 40S.
A POTENT UPPER LEVEL SYSTEM CONSISTING OF SEVERAL STRONG SHORT
WAVES ROTATING AROUND THE CORE WILL BEGIN TO MOVE OVER CALIFORNIA
ON FRIDAY. ANOTHER SHORT WAVE UNDERCUTTING THE SYSTEM WILL PUSH
OUT AHEAD AND ARRIVE OVER NEBRASKA AND IOWA BY FRIDAY NIGHT. AN
INCREASING LOW LEVEL JET AND ASSOCIATED STRONG THETA-E ADVECTION
ALONG WITH THE QG FORCING FROM THE UPPER WAVE WILL HELP SHOWERS
AND A FEW THUNDERSTORMS DEVELOP ACROSS MAINLY CENTRAL AND WESTERN
IOWA. OVERNIGHT LOW TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE
FREEZING WITH LOW LEVEL MOISTURE SURGE BRINGING DEWPOINTS IN THE
3OS TO THE AREA. THE FORECAST AREA WILL BE IN THE WARM SECTOR
THROUGH THE DAY SATURDAY. THE PRIMARY UPPER LEVEL SYSTEM WILL LIFT
INTO THE MIDWEST SATURDAY NIGHT INTO SUNDAY. THE ECMWF IS A BIT
FASTER WITH THE SFC FEATURES WITH THE COLD FRONT DROPPING THROUGH
MUCH OF CENTRAL IOWA BY 12Z SUNDAY WHILE THE GFS IS A BIT SLOWER.
ANY PRECIPITATION WILL SWITCH OVER TO SNOW BEHIND THE COLD FRONT
AS PROFILES COOL. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE. COLD
ADVECTION WILL BE PROMINENT MUCH OF THE DAY SUNDAY WITH HIGH
TEMPERATURES EARLY IN THE DAY. 850 MB TEMPERATURES BY 12Z MONDAY
WILL BE -8C TO -10C ACROSS MUCH OF THE AREA AND HAVE CONTINUED THE
COOLING TREND INTO MONDAY. SOME MODERATION FOR THE END OF THE
PERIOD WITH LOW CHANCES FOR PRECIPITATION.
&&
.AVIATION...06/18Z
STRATUS WILL PERSIST ACROSS THE AREA THROUGH THE PERIOD. CEILINGS
WILL VARY BETWEEN LOW MVFR AND HIGH IFR AT TIMES...AND MAY
OCCASIONALLY SCATTER TO VFR AT SITES. HOWEVER...OVERALL TREND WILL
BE FOR MVFR CEILINGS. COULD SEE SOME BR/FG DEVELOP AT EASTERN SITES
KMCW/KALO/KOTM NEAR 12Z AS INVERSION SETS UP...BUT DO NOT HAVE
ENOUGH CONFIDENCE TO INCLUDE MENTION ATTM. NORTHWESTERLY WINDS WILL
DECREASE IN THE AFTERNOON BEFORE SHIFTING TO THE SOUTHEAST LATE IN
THE PERIOD AND WILL BE STRONG AFTER 12Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1050 AM CST WED MAR 6 2013
.UPDATE...
BASED ON DATA THROUGH MID MORNING...CLEARING TODAY IS DOUBTFUL AND
QUESTIONABLE FOR TONIGHT. SATELLITE DOES SHOW HOLES IN THE CLOUD COVER
THAT IS APPROXIMATED BY THE 0.5 KM RH OF THE RAP.
THE 12Z UA DATA SHOWED A THIN LAYER OF MOISTURE TRAPPED BELOW THE
INVERSION. RAP TRENDS WITH CONDENSATION PRESSURES AND WIND AT THE
0.5 KM LEVEL DO NOT SHOW ANY SUBSTANTIAL FORCING TO HELP BREAK UP
THE CLOUDS TODAY IN SPITE OF THE STRONGER MARCH SUNSHINE. THE 0.5
KM CONDENSATION PRESSURE SUGGESTS THE HOLE ALONG THE MISS RIVER IN
WESTERN WISCONSIN MAY DRIFT SLOWLY SOUTH DURING THE DAY AND
POSSIBLY CLIP THE FAR NORTHWEST PARTS OF THE CWFA.
IF THE RAP TRENDS ARE CORRECT...THEN CLOUDS MAY NOT BREAK UP
TONIGHT OR ONLY A FEW HOLES MAY DEVELOP.
SO...WILL UPDATE THE FCST TO BE MORE PESSIMISTIC ON CLEARING TODAY
AND AT LEAST INTO THE EVENING HOURS. ..08..
&&
.AVIATION...
MOISTURE TRAPPED BELOW THE INVERSION IS RAISING QUESTIONS ON THE
MVFR CONDITIONS CLEARING LATER TODAY. RAP MODEL TRENDS SUGGESTS
THE THIN LAYER OF MOISTURE REMAINS TRAPPED AND MAY REMAIN IN PLACE
UNTIL AFTER 12Z/07. THE POTENTIAL DOES EXIST FOR BREAKS IN THE
CLOUD COVER THAT COULD ALLOW POCKETS OF VFR CONDITIONS TO DVLP BUT
MAY NOT NECESSARILY BE OVER ANY TAF SITE. ..08..
&&
.PREV DISCUSSION... /ISSUED 541 AM CST WED MAR 6 2013/
SYNOPSIS...
ISSUED AT 331 AM CST WED MAR 6 2013
CONDITIONS MUCH QUIETER TONIGHT WITH THE STRONG SURFACE LOW
ASSOCIATED WITH THE TUESDAY SNOW NOW EXITING EAST ACROSS OHIO AS
OF 3 AM THIS MORNING. NORTHWEST FLOW CONTINUES ACROSS THE AREA
WITH WIDESPREAD LOW CLOUDS. A FEW FLURRIES WERE LINGERING OVER THE
AREA AROUND MIDNIGHT...BUT THESE HAVE SINCE DISSIPATED. THERE ARE
SOME HOLES IN THE STRATUS...BUT THESE ARE RELATIVELY TRANSITORY
AND ARE NOT VISIBLY EXPANDING. IT APPEARS TO BE LOOSELY RELATED TO
SOME MID LEVEL DIVERGENCE...WHICH IS SLOWLY SHIFTING SOUTH ACROSS
THE AREA OVERNIGHT. THIS DIVERGENCE WEAKENS AND SHIFTS OUT OF THE
AREA IN THE NEXT SEVERAL HOURS. WILL BE WATCHING TRENDS TO SEE IF
THE STRATUS FILLS BACK IN. ..LE..
SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 331 AM CST WED MAR 6 2013
THE MAIN CONCERN BOTH PERIODS IS FOR HOW THE STRATUS EVOLVES OVER
THE NEXT 24 HOURS...AND ITS RELATED EFFECT ON TEMPERATURES.
TODAY...MODEL GUIDANCE IS PERSISTENT IN BREAKING UP THE LOW STRATUS
DURING LATE MORNING OR AFTERNOON HOURS. NONE OF THE MODEL GUIDANCE
IS DOING ESPECIALLY WELL WITH THESE LOW CLOUDS...MOST NOT DEPICTING
ENOUGH AREAL EXTENT AT INITIALIZATION. HOWEVER...A MORE DETAILED
LOOK AT 925MB RH GRIDS AND SOUNDINGS IMPLIES A MORE PESSIMISTIC
PICTURE. THIS LOW LEVEL RH IS TRAPPED BENEATH A LOW LEVEL
INVERSION...WHICH LIFTS DURING THE DAYTIME...BUT DOES NOT BREAK.
EXPECT THAT THE CEILINGS MAY LIFT INTO A MORE MVFR LAYER...BUT WILL
STILL BE THERE. ALSO...WE DO NOT HAVE ANY PARTICULARLY DRY AIR OR
PARTICULARLY STRONG SUBSIDENCE WORKING INTO THE AREA TODAY.
HOWEVER...THIS IS EARLY MARCH AND WE ARE WORKING WITH FAIRLY STRONG
SUNSHINE...AND CLOUDS MAY BREAK UP AS DEPICTED. SO...WHILE AM NOT
TERRIBLY OPTIMISTIC...HAVE ALLOWED CLOUD COVER TO DECREASE THIS
AFTERNOON. THE EFFECT ON TODAYS HIGH TEMPS WILL NOT BE VERY
NOTICEABLE...AND WITH THE WEAK COLD AIR ADVECTION STILL
ONGOING...EXPECT HIGHS IN THE UPPER 20S TO LOW 30S.
TONIGHT THE REAL TROUBLE WITH THE STRATUS KICKS IN...AS IT COULD
HAVE A FAIRLY MAJOR EFFECT ON THE MIN TEMPS TONIGHT. AGAIN...NEARLY
ALL GUIDANCE IMPLIES THAT WE WILL CLEAR OUT DURING THE AFTERNOON AND
BE CLEAR OR NEARLY CLEAR OVERNIGHT. MODEL GUIDANCE FOLLOWS THIS
WITH MIN TEMPS IN THE SINGLE DIGITS NORTH AND LOWER TEENS SOUTH.
ONCE AGAIN THOUGH...925MB RH VALUES IMPLY A PERSISTENT LAYER OF
RH...WITH NO STRONG FEATURES TO DRIVE THE LOW LEVEL RH OUT OF THE
AREA. SOUNDINGS ALSO SUPPORT THIS TRAPPED LOW LEVEL MOISTURE.
RIGHT NOW THE STRATUS EXTENDS BACK TO THE SURFACE RIDGE AXIS IN
NEBRASKA AND THE DAKOTAS...AND SEE NO FEATURES IN THE FORECAST OTHER
THAN SUNSHINE THAT COULD POSSIBLY MIX THE STUFF OUT DURING THE
DAYTIME OR EARLY EVENING. SO...IF WE CANNOT CLEAR THE STRATUS
DURING THE AFTERNOON...WE MAY HAVE CLOUD COVER FOR THE OVERNIGHT TO
PUT A BLANKET ON THE RADIATIONAL COOLING. WITH CLOUD COVER...EXPECT
ANOTHER NIGHT IN THE UPPER TEENS TO LOW 20S. THUS...WE HAVE A
FAIRLY LARGE BUST POTENTIAL FOR TONIGHT WITH THIS SKY COVER
DILEMMA. FOR NOW HAVE THE MOSTLY CLEAR SKIES GOING IN THE
FORECAST...WITH THE COLDER SCENARIO FOR MIN TEMPERATURES...BUT THE
NEXT SHIFT IS GOING TO HAVE TO REEVALUATE THOSE LOW CLOUDS AND
WHETHER THEY ARE GOING TO PERSIST INTO THE NIGHTTIME HOURS OR NOT.
.LE..
LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 331 AM CST WED MAR 6 2013
PRIMARY FOCUS IS ON A WARMING TREND AND RAIN CHANCES THIS WEEKEND.
THIS WILL OCCUR AS THE UPPER LOW CURRENTLY OFF THE PACIFIC NW COAST
IS PROGGED TO DIG INTO THE 4 CORNERS REGION FRIDAY NIGHT...THEN LIFT
NORTHEAST INTO THE CENTRAL U.S. BY SUNDAY AND MONDAY. AHEAD OF
THIS...A SW FLOW WILL FEED GULF MOISTURE INTO THE PLAINS BY
FRIDAY...REACHING INTO THE LOCAL FORECAST AREA SATURDAY. AT THE
SURFACE...LOW PRESSURE EMERGES TO LEE OF THE CENTRAL ROCKIES INTO
THE PLAINS FRIDAY NIGHT...THEN LIFTS NORTHEAST ALONG A SW TO NE
ORIENTED FRONTAL AXIS...THROUGH THE MID OR UPPER MS VALLEY OVER THE
WEEKEND. WHILE THE LATEST MODELS HAVE COME INTO BETTER AGREEMENT
WITH THIS OVERALL SCENARIO THAN LAST NIGHT/S RUNS...THERE REMAIN
CONSIDERABLE DIFFERENCES WITH THE TRACK AND TIMING OF THE SURFACE
LOW AND THE ASSOCIATED AMOUNT OF PHASING OF UPPER LEVEL WAVES. THE
ECMWF REMAINS SLOWER AND DOES NOT DEPICT THE GFS/S PHASING OF THE
500 MB LOW MOVING OUT OF THE SW WITH A NORTHERN STREAM TROUGH MOVING
ACROSS SOUTHERN CANADA. THIS RESULTS IN THE GFS BECOMING A MUCH MORE
PROGRESSIVE SOLUTION AND TAKING THE SURFACE LOW ON A MORE NORTHERLY
TRACK...ESPECIALLY SUNDAY AND BEYOND. FOR NOW...WILL PREFER THE
SLOWER ECMWF...BASED ON EXPERIENCE WITH SIMILAR COOL SEASON SYSTEMS
LIFTING OUT OF THE SW.
THURSDAY AND FRIDAY WILL BE PROGRESSIVELY WARMER AS THE SURFACE
RIDGE SHIFTS EAST OVER THE GREAT LAKES AND WARM ADVECTION INCREASES
ALOFT. DESPITE THE SNOW COVER...STRONG MARCH SUNSHINE SHOULD WARM
MOST AREAS ABOVE FREEZING TO REACH HIGHS IN THE 30S THURSDAY...THEN
INTO THE UPPER 30S NORTH TO NEAR 50 SOUTH ON FRIDAY WHEN SOUTHEAST
WINDS WILL BE STRONGER. THU NIGHT...LOWS RANGE FROM THE UPPER TEENS
NORTHEAST TO MID 20S SOUTHWEST...COUNTING ON AT LEAST SCATTERED MID
CLOUDS AND LIGHT WINDS TO PREVENT POSSIBLE COLDER READINGS OVER THE
LINGERING SNOW COVER.
FRIDAY NIGHT...STRONG WARM ADVECTION ON 850 MB WINDS OF 25 TO 35 KTS
WILL REACH INTO THE AREA BY MORNING. MOISTURE RETURN...HOWEVER...IS
MAINLY CONFINED TO THE SW OR WESTERN REACHES OF THE FORECAST AREA
TOWARD MORNING DEPENDING ON THE MODEL. THIS MAY TRIGGER SOME SHOWERS
AND HAVE SLIGHT CHANCES IN PLACE IN THE WEST AFTER MIDNIGHT. THERE
IS A POSSIBILITY THAT SURFACE TEMPERATURES COULD BE NEAR OR BELOW
FREEZING AT ONSET ESPECIALLY ACROSS THE NORTH FOR A THREAT OF BRIEF
FREEZING RAIN...BUT CONFIDENCE IS TOO LOW TO INCLUDE MENTION IN THE
FORECAST.
SATURDAY AND SATURDAY NIGHT...THE MAIN FEED OF GULF MOISTURE
OVERSPREADS THE AREA UNDER AN INCREASINGLY DIFFLUENT FLOW ALOFT AND
LIKELY POPS ARE IN PLACE FOR RAIN IN THE WEST DURING THE DAY AND
OVER THE ENTIRE AREA SATURDAY NIGHT FOR WHAT COULD BE WIDESPREAD
MODERATE AMOUNTS. SUNDAY...THE COLD FRONT PUSHES THROUGH THE AREA
IN SOME FASHION...LIKELY CHANGING THE RAIN TO SNOW FROM NW TO SE BY
EVENING AND CANNOT RULE OUT SOME SNOW ACCUMULATIONS AS PRECIPITATION
CONTINUES SUNDAY NIGHT. HIGHS SATURDAY AND SUNDAY SHOULD BE WELL
INTO THE 40S AND POSSIBLY LOWER 50S...FOLLOWED BY 30S AND POSSIBLY
LOWER 40S EARLY NEXT WEEK AS THE UPPER FLOW BECOMES NW AND HIGH
PRESSURE BUILDS INTO THE UPPER MS VALLEY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1242 PM EST WED MAR 6 2013
.UPDATE...
ISSUED AT 1151 AM EST WED MAR 6 2013
ONLY MINOR ADJUSTMENTS TO THE GOING FORECAST...MOST OF WHICH WERE
DONE EARLIER TO EXPAND THE SOUTHERN EXTENT OF THE SNOWFALL TO SHOW
A PERIOD OF SNOW MOVING EAST THROUGH THE AREA. THIS SNOW IS
ASSOCIATED WITH THE SHORTWAVE SEEN ON WV IMAGERY MOVING ACROSS
WESTERN LAKE SUPERIOR AND INTO WESTERN UPPER MICHIGAN AND AN
AREA OF MID LEVEL FGEN AND Q-VECTOR CONVERGENCE. OVER THE
LAST HOUR OR TWO...THE SNOW HAS INCREASED IN INTENSITY ON RADAR AND
WE HAVE SEEN 1.1 INCHES THUS FAR AT THE OFFICE. THUS...TWEAKED UP
SNOWFALL AMOUNTS OVER THE NORTH HALF OF THE EASTERN CWA TO AN
ADDITIONAL INCH THROUGH THE AFTERNOON.
DRY AIR SURGING IN BEHIND THE SHORTWAVE HAS BROUGHT AN END TO THE
SYNOPTIC SNOW OUT WEST AND VISIBLE SATELLITE SHOWS THAT LAKE EFFECT
SNOW BANDS HAVE DEVELOPED OVER THE WESTERN LAKE. WILL HOLD ONTO
SCATTERED SNOW SHOWERS OVER THE WEST THROUGH THE AFTERNOON AND HAVE
MADE AN ADJUSTMENT UP TO POPS /TO HIGH END SCATTERED/ OVER THE
KEWEENAW THIS EVENING...AS COLDER AIR ROTATES SOUTHEAST BEHIND THE
SHORTWAVE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST WED MAR 6 2013
INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE
NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP
TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS
BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR
OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS
MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION
THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY
SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH.
TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF
THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR
WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH
OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING
ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH.
FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS
AROUND 600MB.
STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING
NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH.
THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING.
MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON
WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS
MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING
THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER
MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE
WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS
SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM
GUIDANCE.
MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK
MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES
WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE
CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF
A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT
GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF
LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI
BORDER.
OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS
ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN.
ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA.
TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL
AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD
LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW
STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING
CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN
SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS
THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE
ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS
A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS
DROP BELOW ZERO IN A FEW SPOTS WELL INLAND.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 534 AM EST WED MAR 6 2013
HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS
EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE
STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL
BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS.
UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN
DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE
AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS
ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET
OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID
TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX
MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN
INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY
FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST
HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG
LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH
HIGHS GENERALLY IN THE LOWER TO MID 30S.
BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE
PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE
MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO
INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN
THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE
SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE
MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL
HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST
FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF
SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST
AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON
SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY
SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE
DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB
TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF
RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST
...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST
HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT
NIGHT.
HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO
SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT
FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE
UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM
SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING
OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR
IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW.
MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE
THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE
ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA
FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL
CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1241 PM EST WED MAR 6 2013
SHORTWAVE THAT BROUGHT THE SNOW TO ALL THREE TAF SITES THIS MORNING
SHOULD CONTINUE EAST THIS AFTERNOON AND BRING AN END TO THE
MODERATE SNOW AT KSAW WITHIN THE NEXT HOUR OR TWO. FOCUS THEN TURNS
TO LAKE EFFECT SNOW WITH THE NORTHWEST WINDS...ESPECIALLY FOR KCMX.
WITH COLDER AIR MOVING SOUTHEAST THROUGH THIS EVENING...EXPECT
LIGHT LAKE EFFECT TO AFFECT KCMX/KIWD THROUGH THE AFTERNOON WITH
MVFR CEILINGS. AS A POCKET OF COLDER AIR MOVES OVER THE KEWEENAW
THIS EVENING...HAVE TRIED TO SHOW A PERIOD OF STRONGER SNOW SHOWERS
BEFORE DRIER AIR FROM AN APPROACHING HIGH PRESSURE MOVES IN
OVERNIGHT. THIS SHOULD BRING AN END TO THE SNOW TONIGHT AND THEN
EVENTUALLY DIMINISH THE CLOUDS TOMORROW MORNING/AFTERNOON.
AT KSAW...HELD ONTO THE MVFR CEILINGS THROUGH MUCH OF THE
NIGHT...BUT THERE IS THE POTENTIAL THEY COULD SCATTER OUT OR GO TO
VFR WITH THE LIGHT DOWNSLOPING NORTHWEST FLOW. DEFINITELY FOLLOWED
THAT TREND FOR TOMORROW MORNING...ALTHOUGH THERE COULD BE DIURNAL CU
REDEVELOPING TOWARDS THE END OF THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST WED MAR 6 2013
A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW
WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE
THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE
ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS.
EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON
FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL
AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR
AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY
AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...TK
LONG TERM...VOSS
AVIATION...SRF
MARINE...TK
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1152 AM EST WED MAR 6 2013
.UPDATE...
ISSUED AT 1151 AM EST WED MAR 6 2013
ONLY MINOR ADJUSTMENTS TO THE GOING FORECAST...MOST OF WHICH WERE
DONE EARLIER TO EXPAND THE SOUTHERN EXTENT OF THE SNOWFALL TO SHOW
A PERIOD OF SNOW MOVING EAST THROUGH THE AREA. THIS SNOW IS
ASSOCIATED WITH THE SHORTWAVE SEEN ON WV IMAGERY MOVING ACROSS
WESTERN LAKE SUPERIOR AND INTO WESTERN UPPER MICHIGAN AND AN
AREA OF MID LEVEL FGEN AND Q-VECTOR CONVERGENCE. OVER THE
LAST HOUR OR TWO...THE SNOW HAS INCREASED IN INTENSITY ON RADAR AND
WE HAVE SEEN 1.1 INCHES THUS FAR AT THE OFFICE. THUS...TWEAKED UP
SNOWFALL AMOUNTS OVER THE NORTH HALF OF THE EASTERN CWA TO AN
ADDITIONAL INCH THROUGH THE AFTERNOON.
DRY AIR SURGING IN BEHIND THE SHORTWAVE HAS BROUGHT AN END TO THE
SYNOPTIC SNOW OUT WEST AND VISIBLE SATELLITE SHOWS THAT LAKE EFFECT
SNOW BANDS HAVE DEVELOPED OVER THE WESTERN LAKE. WILL HOLD ONTO
SCATTERED SNOW SHOWERS OVER THE WEST THROUGH THE AFTERNOON AND HAVE
MADE AN ADJUSTMENT UP TO POPS /TO HIGH END SCATTERED/ OVER THE
KEWEENAW THIS EVENING...AS COLDER AIR ROTATES SOUTHEAST BEHIND THE
SHORTWAVE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST WED MAR 6 2013
INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE
NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP
TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS
BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR
OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS
MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION
THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY
SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH.
TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF
THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR
WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH
OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING
ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH.
FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS
AROUND 600MB.
STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING
NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH.
THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING.
MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON
WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS
MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING
THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER
MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE
WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS
SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM
GUIDANCE.
MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK
MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES
WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE
CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF
A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT
GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF
LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI
BORDER.
OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS
ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN.
ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA.
TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL
AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD
LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW
STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING
CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN
SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS
THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE
ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS
A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS
DROP BELOW ZERO IN A FEW SPOTS WELL INLAND.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 534 AM EST WED MAR 6 2013
HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS
EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE
STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL
BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS
THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST
PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY
SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS.
UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN
DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE
AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS
ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET
OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID
TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX
MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN
INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY
FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST
HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG
LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH
HIGHS GENERALLY IN THE LOWER TO MID 30S.
BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE
PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE
MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO
INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN
THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE
SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE
MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL
HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST
FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF
SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST
AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON
SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY
SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE
DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB
TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF
RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST
...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST
HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT
NIGHT.
HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO
SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT
FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE
UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM
SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING
OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR
IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW.
MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE
THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE
ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA
FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL
CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 648 AM EST WED MAR 6 2013
A WEAK TROUGH MOVING THROUGH THE AREA WILL BRING LIGHT SNOW TO ALL
TAF SITES TODAY...AFFECTING IWD AND CMX THIS MORNING...AND SAW
THROUGH THE AFTERNOON. VIS SHOULD REMAIN GENERALLY IN THE IFR
RANGE...WITH CIGS IN THE MVFR RANGE. UPSLOPE WINDS AT ALL SITES WILL
HELP KEEP CIGS LOWER FOR MUCH OF THE DAY. THE TROUGH WILL MOVE EAST
DURING THE DAY...BUT EXPECT LAKE ENHANCED SNOW SHOWERS TO CONTINUE
INTO THE EVENING NEAR LAKE SUPERIOR. VIS SHOULD IMPROVE AT ALL SITES
BY LATE THIS AFTERNOON WHILE CIGS REMAIN IN THE MVFR RANGE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST WED MAR 6 2013
A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW
WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE
THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE
ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS.
EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON
FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL
AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR
AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY
AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...TK
LONG TERM...VOSS
AVIATION...TK
MARINE...TK
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
406 PM CST WED MAR 6 2013
.DISCUSSION...
TONIGHT...CLOUDS HAVE BEEN THINNING OUT ALL AFTERNOON...AND ITS
CURRENTLY PRETTY CLEAR OVER WRN WI. THE STRATUS DECK IS MORE
EXTENSIVE FURTHER WEST...AND WITH HIGH PRESSURE MOVING OVERHEAD
TONIGHT...THE CLOUDS MAY BECOME TRAPPED UNDER THE INVERSION. THE
FCST HAS TRENDED WARMER FOR OVERNIGHT LOWS /ESPECIALLY ACROSS WC
MN/ WHERE CLOUDS ARE ANTICIPATED TO HANG ON THE LONGEST. TEMPS ARE
EXPECTED TO RANGE FROM THE LOWER TEENS ALONG AND WEST OF THE MN
RIVER...TO NEAR ZERO IN W WI. WHERE CLEARING DOES
OCCUR...RADIATIONAL FOG MAY BECOME AN ISSUE. E CENTRAL MN AND W WI
HAVE THE BEST SHOT OF SEEING PATCHY FOG WHERE SKIES SHOULD BE
CLEAR THE LONGEST. NOT EXPECTING EXTENSIVE DENSE FOG...BUT WOULD
NOT BE SURPRISED IF A FEW SITES DIP AS LOW AS 1/2SM FOR A TIME
EARLY THU AM.
THURSDAY AND FRIDAY...SURFACE HIGH PRES WILL SLIDE E ACRS THE
AREA...RESIDING E OF THE AREA BY THU MRNG. IN CONJUNCTION WILL BE
A LONGWAVE UPPER LEVEL RIDGE THAT WILL GLIDE ACRS THE REGION.
WHILE THE SFC HIGH E OF THE REGION WILL ALLOW FOR A SOUTHERLY
WARMER RETURN SFC FLOW...THE UPPER RIDGING WILL BRING HIGHER H7
AND H5 HEIGHTS THAT WILL ALSO PROMOTE WAA FOR THE REGION FOR BOTH
THU-FRI. THIS COMBINATION WILL ALSO KEEP ANY SIGNIFICANT WX
SYSTEMS FROM IMPACTING THE REGION SO TEMPERATURES WILL RISE TO
NEAR NORMAL LEVELS...WHICH WILL ACTUALLY SEEM LIKE A SIGNIFICANT
WARMUP FOR THE REGION. HIGHS WILL REACH THE FREEZING MARK ON THU
THEN JUMP TO THE MID AND EVEN UPPER 30S ON FRI. THIS WILL ALLOW
FOR DECENT MELTING OF THE SNOWPACK AND SHOULD CAUSE AN APPRECIABLE
DECREASE IN SNOW DEPTH. CLOUDS WILL BE ON THE INCREASE FRI WHICH
MAY HINDER SOME EVAPORATION BUT THE MELTING SHOULD NOT BE IMPACTED
AS MUCH SIMPLY WITH TEMPERATURES WELL ABOVE THE FREEZING MARK. OF
COURSE...THE MELTING FOLLOWED BY REFREEZING AT NIGHT MAY CAUSE
SOME SLIPPERY ROADS BUT IT IS A LITTLE EARLY TO DETERMINE THE
EXTENT OF SUCH CONCERNS.
FRIDAY NIGHT THROUGH TUESDAY...SEVERAL LOW PRESSURE SYSTEMS LOOK
TO IMPACT THE AREA LATE THIS WEEK INTO EARLY NEXT WEEK WITHIN A
PROGRESSIVE SW FLOW ON THE BACKSIDE OF THE DEPARTING UPPER LEVEL
RIDGE. A LARGE LONGWAVE TROUGH DIGGING INTO THE 4-CORNERS REGION
WILL EJECT A LOW PRESSURE SYSTEM FROM THE COLORADO REGION EWD INTO
THE MID-MISSISSIPPI RIVER VALLEY. HIGH PRES NUDGING DOWN FROM
CENTRAL CANADA WILL KEEP THE BULK OF THIS SYSTEM FROM SHIFTING
N...BUT ENOUGH UPPER LEVEL TROFFING COMBINED WITH AN ATTENDANT SFC
TROUGH WILL ALLOW PRECIPITATION TO DEVELOP FROM S TO N STARTING
FRI NIGHT AND CONTINUING THRU MOST OF THE WEEKEND. THE CONCERN IS
THAT THERE IS LITTLE TO NO COLD AIR ADVECTION ACCOMPANYING THIS
SYSTEM SO TEMPERATURES WILL STILL RANGE THROUGH THE 30S DURING THE
DAYTIME HOURS FRI-SUN AND IN THE 20S TO NEAR 30 FRI NIGHT AND SAT
NIGHT. IN ADDITION...MODEL SOUNDINGS CONTINUE TO ADVERTISE VARYING
AREAS THAT WILL DEAL WITH A SHALLOW WARM AIR LAYER OF VARYING
DEPTHS...MAKING P-TYPE ISSUES HIGHLY COMPLEX. HAVE CONTINUED TO
ADVERTISE A VARIETY OF WINTRY PRECIPITATION FOR THE WEEKEND AND
LATER FORECASTS WILL NEED TO BE ADVERTISED. IN ADDITION...QPF
LOOKS TO BE HIGHLY ELEVATED WITH SOME MODELS SHOWING AT LEAST AN
INCH THROUGH THE WEEKEND...WHICH MAY MAKE FOR HYDROLOGIC
CONCERNS...ESPECIALLY ANY SIGNIFICANT RAINFALL ON TOP OF A DECENT
SNOWPACK. ONCE THIS COMPLEX SYSTEM SHIFTS OFF TO THE SE SUN NIGHT
INTO MON...COLDER HIGH PRES WILL DROP DOWN FROM CANADA MAKING FOR
A DRYING OUT PERIOD MON-TUE ALONG WITH TEMPERATURES BACK DOWN
BELOW NORMAL.
&&
.AVIATION.../18Z TAF ISSUANCE/
MAIN ISSUE THIS TAF PERIOD IS WHAT WILL HAPPEN WITH EXPANSIVE
STRATUS DECK IN PLACE. SFC RIDGE AXIS IS CURRENTLY FROM NEAR SIOUX
FALLS TO BISMARK...WITH CONDS MAINLY VFR WEST OF THIS AXIS. THE
RIDGE WILL SLIDE ACROSS THE MPX AREA TONIGHT...WHICH WOULD IMPLY
SKIES SHOULD CLEAR OUT FROM WEST TO EAST...BUT THIS IS LOOKING
LIKE A SCENARIO WHERE LOW LEVEL MOISTURE GETS TRAPPED BENEATH THE
INVERSION AND IT TAKES A NEW ROUND OF SOLAR MIXING THURSDAY
MORNING TO FINALLY BLAST THE LOW CLOUDS OUT. THIS IS THE SCENARIO
THE HRRR PLAYS OUT AND IN GENERAL WHAT WAS FOLLOWED FOR THESE TAFS.
ONE THING TO WATCH CLOSELY THOUGH THIS AFTERNOON IS WHAT HAPPENS
TO THE HOLE IN STRATUS OVER WRN WI...IF THIS CAN EXPAND SOME THIS
AFTERNOON...THEN THERE IS A GOOD CHANCE THAT SKIES WILL STAY CLEAR
ACROSS ERN TERMINALS. IF THIS HAPPENS...THEN RNH/EAU WILL LIKELY
HAVE TO WORRY ABOUT FOG IN THE MORNING.
KMSP...CONFIDENCE IN OPTIMISTIC SKY FORECAST THIS EVENING IS LOW.
GOING VFR AT 4Z WILL WORK OUT...SO LONG AS THE CLEARING TO THE
EAST CAN EXPAND AND SUSTAIN ITSELF. HOWEVER...COULD VERY WELL SEE
THIS NOT HAPPENING...WITH CIGS REMAINING BETWEEN 020 AND 025 UNTIL
AFTER 12Z THU...WITH THE POTENTIAL FOR GOING BELOW 017 LATE
TONIGHT. FOR WIND DIRECTION...THE SWITCH TOWARD THE SE WILL
HAPPEN OVERNIGHT. WITH SPEEDS UNDER 7 KTS...SHOULD GIVE SOME LEE
WAY IN RUNWAY CONFIG. BY THU MORNING THOUGH...BOTH NAM/GFS SHOW SE
WINDS INCREASING IN INTENSITY...SO WILL MOST LIKELY HAVE TO START
TOMORROW ON THE 12S.
/OUTLOOK FOR KMSP/
FRI...VFR. MVFR CIGS WITH CHANCE OF FZRA/RA LATE FRI NIGHT. SE
WIND 5-10 KTS.
SAT...IFR OR LOWER WITH CHANCE OF FZRA/RA. WINDS E 5 KTS.
SUN...MVFR WITH CHANCE OF -SN EARLY. WINDS N 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JPC/JCA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1235 PM CST WED MAR 6 2013
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.PREV DISCUSSION...
/ISSUED 515 AM CST WED MAR 6 2013/
MAIN FORECAST CONCERN IS THE PRECIPITATION TYPE FOR THE UPCOMING
WEEKEND...AND WHETHER THERE WILL BE ICE PROBLEMS.
THE STORM SYSTEM THAT HAS PLAGUED THE UPPER MIDWEST FOR THE PAST
TWO DAYS HAS MOVED SOUTHEAST AND AFFECTING THE MID-ATLANTIC
REGION. RESIDUAL CLOUD COVER AND COOL NORTHERLY FLOW WILL KEEP
TEMPS FROM RISING ABV FREEZING FOR THE MOST PART TODAY.
HOWEVER...THE MARCH SUN ANGLE IS HIGH ENOUGH TO START THE MELTING
PROCESS ACROSS THE REGION...BUT IT SHOULD BE LIMITED WITH THE AMT
OF CLOUD COVER EXPECTED. AS THE SFC RIDGE MOVES OVERHEAD
TONIGHT...SOME FOG WILL DEVELOP...ESPECIALLY ACROSS EASTERN
MN...AND WESTERN WI WHERE WINDS WILL BE LIGHTEST.
AFTER WEDNESDAY...A LARGE RIDGE WILL DEVELOP ACROSS THE UPPER
MIDWEST IN RESPONSE TO A SHARP TROUGH DIGGING INTO THE SW U.S.
THIS WILL ALLOW FOR MUCH WARMER AIR TO SURGE NORTHWARD ACROSS THE
PLAINS...AND THE UPPER MIDWEST BY THE END OF THE WEEK.
BASED ON THE AMT OF MOISTURE EXPECTED AHEAD OF THIS SYSTEM...WHICH
TRANSLATES TO PRECIPITABLE WATER VALUES NEAR 0.80 INCHES /THIS IS
ALMOST TWO STANDARD DEVIATIONS ABV NORMAL FOR MSP/ PRECIPITATION
IS ALMOST CERTAIN BY LATE FRIDAY/SATURDAY. DEPENDING UPON SFC
TEMPS INITIALLY...FREEZING RAIN/SLEET/SNOW WILL OCCUR AT THE
BEGINNING LATE FRIDAY NIGHT/EARLY SATURDAY...BEFORE CHANGING OVER
TO A MIXTURE OF SNOW/RAIN...OR JUST RAIN. DUE TO THE AMT OF WARM
AIR ADVECTING NORTHWARD AND HOW 85H DEW PTS RISE ABV 0C...AM
THINKING THAT MOST OF THE PRECIPITATION WILL BE IN THE FORM OF
LIQUID. ONLY THE FAR NORTH/NW FA MAY SEE A MIXTURE BASED ON THE
MAX WET BULB TEMPS IN THE MIX LAYER UP TO 1KM.
THERE REMAINS A LOT OF CONCERN WITH THE DEEP SNOW PACK ACROSS OUR
REGION...WHICH MAY HOLD DOWN TEMPS INITIALLY...SO A PERIOD OF
SLEET/FREEZING RAIN IS BECOMING LIKELY. WILL UPDATE THE MORNING
HWO BASED ON THIS SCENARIO. QPF AMTS ARE ALSO VERY HIGH...AND MAY
CAUSE SOME FLOODING IF WE GET SOME TYPE OF CONVECTIVE ELEMENT
SATURDAY AFTN. THIS IS MAINLY DUE TO THE FROZEN GROUND AND
ABUNDANT SNOW COVER. AS DEW PTS ARE EXPECTED TO RISE ABV FREEZING
AND THE COMBINATION OF RAIN ON SNOW FALLING...AND POSSIBLY HIGHER
PRECIPITATION RATES...SOME MINOR FLOODING IS POSSIBLE.
A COLD FRONT IS EXPECTED TO MOVE ACROSS THE REGION LATE SATURDAY
AFTN/EVENING...CAUSING THE PRECIPITATION TO SWITCH OVER TO SNOW.
HOWEVER...BUT THAT TIME...MOST OF THE DEEP MOISTURE WOULD BE
GONE...LEAVING ONLY LIGHT SNOW AT BEST.
ALTHOUGH LONG RANGE CLIMATE MODELS ARE HINTING ON A COOLER PATTERN
THE MIDDLE OF MARCH...THE LATEST EC/GFS IS CONSIDERING A MORE
ZONAL FLOW BY LATE NEXT WEEK. THIS WOULD LEAN TOWARD A MORE
MODERATING TREND...AND NOT SO COLD. ..JLT..
&&
.AVIATION.../18Z TAF ISSUANCE/
MAIN ISSUE THIS TAF PERIOD IS WHAT WILL HAPPEN WITH EXPANSIVE
STRATUS DECK IN PLACE. SFC RIDGE AXIS IS CURRENTLY FROM NEAR SIOUX
FALLS TO BISMARK...WITH CONDS MAINLY VFR WEST OF THIS AXIS. THE
RIDGE WILL SLIDE ACROSS THE MPX AREA TONIGHT...WHICH WOULD IMPLY
SKIES SHOULD CLEAR OUT FROM WEST TO EAST...BUT THIS IS LOOKING
LIKE A SCENARIO WHERE LOW LEVEL MOISTURE GETS TRAPPED BENEATH THE
INVERSION AND IT TAKES A NEW ROUND OF SOLAR MIXING THURSDAY
MORNING TO FINALLY BLAST THE LOW CLOUDS OUT. THIS IS THE SCENARIO
THE HRRR PLAYS OUT AND IN GENERAL WHAT WAS FOLLOWED FOR THESE TAFS.
ONE THING TO WATCH CLOSELY THOUGH THIS AFTERNOON IS WHAT HAPPENS
TO THE HOLE IN STRATUS OVER WRN WI...IF THIS CAN EXPAND SOME THIS
AFTERNOON...THEN THERE IS A GOOD CHANCE THAT SKIES WILL STAY CLEAR
ACROSS ERN TERMINALS. IF THIS HAPPENS...THEN RNH/EAU WILL LIKELY
HAVE TO WORRY ABOUT FOG IN THE MORNING.
KMSP...CONFIDENCE IN OPTIMISTIC SKY FORECAST THIS EVENING IS LOW.
GOING VFR AT 4Z WILL WORK OUT...SO LONG AS THE CLEARING TO THE
EAST CAN EXPAND AND SUSTAIN ITSELF. HOWEVER...COULD VERY WELL SEE
THIS NOT HAPPENING...WITH CIGS REMAINING BETWEEN 020 AND 025 UNTIL
AFTER 12Z THU...WITH THE POTENTIAL FOR GOING BELOW 017 LATE
TONIGHT. FOR WIND DIRECTION...THE SWITCH TOWARD THE SE WILL
HAPPEN OVERNIGHT. WITH SPEEDS UNDER 7 KTS...SHOULD GIVE SOME LEE
WAY IN RUNWAY CONFIG. BY THU MORNING THOUGH...BOTH NAM/GFS SHOW SE
WINDS INCREASING IN INTENSITY...SO WILL MOST LIKELY HAVE TO START
TOMORROW ON THE 12S.
/OUTLOOK FOR KMSP/
FRI...VFR. MVFR CIGS WITH CHANCE OF FZRA/RA LATE FRI NIGHT. SE
WIND 5-10 KTS.
SAT...IFR OR LOWER WITH CHANCE OF FZRA/RA. WINDS E 5 KTS.
SUN...MVFR WITH CHANCE OF -SN EARLY. WINDS N 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JLT/MPG
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1054 AM CST WED MAR 6 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 332 AM CST WED MAR 6 2013
STILL SEEING SOME WEAK BANDING ON RADAR THIS MORNING THAT IS
CORRESPONDING WITH THE FLURRIES BEING REPORTED IN THE SURFACE
OBSERVATIONS. THIS BANDING LOOKS TO BE SET UP UNDER THE CHANNELED
VORT MAX ON THE WESTERN SIDE OF THE VORT. RAP DEPICTS THAT THIS
VORT WILL MOVE EAST OF THE AREA BY LATE MORNING...SO WILL MAINTAIN
SCT FLURRIES OVER THE EASTERN HALF OF THE CWA THROUGH MID MORNING.
SATELLITE STILL SHOWS EXTENSIVE CLOUDINESS OVER MO/IL EARLY THIS
MORNING...WITH THE BACK EDGE OF THE CLOUDINESS MOVING A BIT TO THE
WEST OVER WESTERN MO/EASTERN KS THE PAST FEW HOURS. THERE HAS BEEN
SOME BREAKS SEEN OVER EASTERN IA WHICH IS COMPLICATING THE CLOUD
FORECAST...THOUGH THESE BREAKS MAY FILL BACK IN DURING THE DAY AS
MOIST LOW LEVEL CYCLONIC FLOW REMAINS OVER THE AREA. IT WILL TAKE
MOST OF THE DAY BEFORE THE LOW LEVEL RIDGE CAN MOVE EAST INTO THE
AREA...SO INCREASED CLOUD COVER FOR THE DAY. CONSEQUENTLY...DO NOT
EXPECT MUCH OF A TEMPERATURE RECOVERY GIVEN THE CLOUDS AND
NORTHWESTERLY FLOW OFF THE LINGERING SNOW PACK.
BRITT
&&
.LONG TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 332 AM CST WED MAR 6 2013
UNSEASONABLY COLD WEATHER IS EXPECTED TGT WITH GOOD RADIATIONAL
COOLING AS THE SKY SHOULD CLEAR OUT AND THE SFC WIND SHOULD BECOME
LIGHT AS THE SFC RIDGE AXIS WILL BE RIGHT OVER THE FORECAST AREA
BY 12Z THU. SFC DEW POINTS WILL ALSO BE QUITE LOW IN THE UPPER
TEENS TO LOWER 20S...PLUS PARTS OF NERN AND CNTRL MO AND W CNTRL
IL WILL STILL HAVE SNOW COVER. A WARMING TREND WILL BEGIN ON THU
AS AN UPPER LEVEL RIDGE OVER THE PLAINS MOVES EWD TO OVER MO BY
00Z FRI...AND THE SFC WINDS BECOME SELY OVER A PORTION OF THE
AREA AS THE SFC RIDGE MOVES EAST OF THE REGION. TEMPERATURES ON
FRI SHOULD BE AT OR ABOVE NORMAL WITH A RELATIVELY STRONG UPPER
LEVEL RIDGE OVER MO AND IL...AND SLY LOW LEVEL WINDS BRINGING
WARMER 850 MB TEMPERATURES NWD INTO OUR AREA. SHOWERS MAY MOVE
INTO PORTIONS OF NERN AND CNTRL MO AS EARLY AS SAT AS A SLY LOW
LEVEL JET BRINGS INCREASING LOW LEVEL WAA AND MOISTURE INTO THIS
AREA WELL AHEAD OF THE UPPER LEVEL LOW AND ASSOCIATED SFC LOW
MOVING EWD FROM THE SRN ROCKIES INTO THE SRN PLAINS. THE GFS MODEL
IS A LITTLE QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL.
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD MOVE INTO MUCH OF
THE FORECAST AREA ON SAT NGT. WILL LEAN TOWARD THE SLOWER
SOLUTION OF THE ECMWF MODEL WHICH HAS ABOVE NORMAL TEMPERATURES
CONTINUING ON SUN WITH THE COLD FRONT MOVING ONLY SLOWLY SEWD
THROUGH OUR AREA AS THE UPPER LEVEL LOW REMAINS CLOSED OFF AND W OF
OUR AREA. COLDER AIR SHOULD ADVECT SEWD INTO THE REGION SUN NGT
BEHIND THE SFC LOW AND TRAILING COLD FRONT WITH THE RAIN POSSIBLY
CHANGING TO SNOW ACROSS PORTIONS OF NERN AND CNTRL MO AS WELL AS W
CNTRL IL. COLDER...BELOW NORMAL TEMPERATURES SHOULD OCCUR ON
MONDAY WITH LINGERING SNOW POSSIBLE AS THE UPPER LEVEL LOW/TROUGH
AND ASSOCIATED SFC LOW SHIFT E OF OUR AREA WITH STRONG CAA LIKELY
ON THE BACKSIDE.
GKS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1049 AM CST WED MAR 6 2013
THE MVFR STRATUS WILL CONTINUE TO LIFT AND THIN THIS AFTERNOON AS
HIGH PRESSURE EDGES EAST INTO MISSOURI. CLEARING TREND SHOULD
CONTINUE INTO THE EVENING WITH MOSTLY CLEAR CONDITIONS OVERNIGHT
AND THURSDAY. PRESSURE GRADIENT BEGINNING TO RELAX ACROSS THE
REGION WITH NORTHWEST WIND DECREASING AND BECOMING LIGHT TONIGHT.
SPECIFICS FOR KSTL...
MVFR STRATUS WILL LIFT TO VFR THIS AFTERNOON AND THEN SCT BY
EVENING. CLEAR CONDITIONS WITH LIGHT AND VARIABLE WIND OVERNIGHT.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
356 PM CST WED MAR 6 2013
.SHORT TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 353 PM CST WED MAR 6 2013
TONIGHT THROUGH MONDAY.
BIGGEST CHALLENGE WILL BE DETERMINING SKY COVER AND VISIBILITY FOR
TONIGHT INTO EARLY THURSDAY MORNING.
THE STRATUS THAT STUCK AROUND AND RETROGRADED WESTWARD INTO THE
EASTERN HALF OF THE CWA HAS LONG MIXED OUT...WITH ONLY SOME CIRRUS
MAKING ITS WAY INTO OUR CWA FROM THE SOUTH/SOUTHWEST.
SATELLITE AND WATER VAPOR REVEAL SPLIT FLOW IN UPPER
LEVELS...PLACING OUR CWA BETWEEN. THE SURFACE RIDGE CONTINUES TO
TREK EAST...WHICH WILL EVENTUALLY TURN WIND TO A MORE SE TO S/SE
WIND DIRECTION. MODELS ARE STILL KEYING IN ON SOME POSSIBLE
STRATUS/FOG IN THE WESTERN CWA OVERNIGHT AND INTO THURSDAY
MORNING...AND WITH THIS CONSISTENT SIGNAL...HAVE LEFT IN THE FOG
FROM THE PREVIOUS FORECAST AND EXPANDED THIS A LITTLE FARTHER TO THE
WEST. THE RAP IS PICKING UP SOME INCREASED STRATUS IN THE WEST AND
EVENTUALLY NORTH AS A LOW-LEVEL JET INCREASED DURING THE OVERNIGHT.
THE NMM ALSO INDICATES SOME INCREASE STRATUS OVERNIGHT...BUT OVER A
LARGER PORTION OF THE CWA. CONFIDENCE REMAINS LOW FOR SKY COVER
TONIGHT AS MODELS DO NOT HAVE A GREAT HANDLE ON LOW-LEVEL SKY COVER
AND FRANKLY...HAVE NOT DONE THAT GREAT FOR AWHILE. THE NAM
ADVERTISES SOME LIGHT QPF IN THE NORTHERN CWA...SOMEWHAT NEAR THE
NOSE OF THE MODEST LOW-LEVEL JET DEVELOPING TONIGHT. WITH SUCH A DRY
PROFILE...I DOUBT IF THERE IS MUCH CHANCE AT ALL OF MEASURABLE
PRECIPITATION...ALTHOUGH THIS COULD BE AN INDICATOR OF SOME
DEVELOPING STRATUS...WHICH SEEMS TO BE SUPPORTED BY THE
USING RECENT VERIFICATION STATISTICS...I MADE SOME MINOR CHANGES
TO TEMPERATURES FOR TONIGHT AND THURSDAY...WITH THE REMAINING
SNOWPACK IN THE WESTERN CWA STILL HAVING SOME INFLUENCE WITH HIGH
TEMPERATURES THURSDAY. THIS SNOWPACK MAY HAVE LIMITED EFFECT ON THE
VISIBILITY FOR OVERNIGHT TONIGHT INTO THURSDAY MORNING AS WELL.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 353 PM CST WED MAR 6 2013
THURSDAY NIGHT THROUGH WEDNESDAY. MAIN FORECAST
CONCERNS ARE PRECIPITATION FRIDAY NIGHT THROUGH SUNDAY NIGHT AND
TEMPERATURES THROUGH THE PERIOD.
AN UPPER LEVEL RIDGE WILL MOVE THROUGH THE AREA THURSDAY NIGHT INTO
FRIDAY. THERE IS WARM ADVECTION ACROSS THE AREA AND TEMPERATURES
SHOULD BE WARMER. IN ADDITION...THE SOUTH WINDS INCREASE THE
MOISTURE ACROSS THE AREA AND CLOUDS WILL INCREASE. A COUPLE OF THE
MODELS HAVE STARTED SHOWING SOME LIGHT QPF ASSOCIATED WITH THE WARM
ADVECTION. HAVE KEPT THE FORECAST DRY FOR NOW AND WILL WAIT FOR
FURTHER RUNS.
BY FRIDAY NIGHT AN UPPER LEVEL LOW PRESSURE SYSTEM MOVING OUT OF THE
ROCKIES WILL START TO AFFECT THE AREA. PRECIPITATION SPREADS ACROSS
THE AREA. WARM TEMPERATURES WILL KEEP PRECIPITATION IN THE FORM OF
RAIN. THERE IS SOME WEAK INSTABILITY WITH MUCAPE UP TO 500 J/KG
ACROSS THE AREA. THERE COULD BE SOME ISOLATED THUNDERSTORMS FRIDAY
NIGHT INTO SATURDAY. SATURDAY WILL CONTINUE TO BE WARM AHEAD OF THE
SURFACE LOW WITH SOUTHERLY WINDS.
THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE TRACK OF THE
UPPER LOW AS IT MOVES THROUGH THE PLAINS. AS THE UPPER LOW MOVES
THROUGH THE PLAINS THE COLDER AIR MOVES INTO THE AREA FROM THE WEST.
SATURDAY NIGHT THE PRECIPITATION CHANGES FROM RAIN TO SNOW IN THE
WEST DURING THE EVENING THEN THE SNOW SPREADS ACROSS THE AREA DURING
NIGHT. BY MORNING EXPECT SNOW IN THE NORTHWEST WITH RAIN AND SNOW
FURTHER SOUTHEAST. ON SUNDAY SNOW WILL BE FOUND ACROSS MUCH OF THE
AREA WITH SOME RAIN OR SNOW POSSIBLE IN THE SOUTHEAST. THE UPPER LOW
WILL SLIDE TO THE EAST SUNDAY NIGHT AND PRECIPITATION WILL COME TO
AN END. PRECIPITATION AMOUNTS ARE NOT VERY HIGH AND EXPECT SOME SNOW
ACCUMULATIONS. SUNDAY WILL BE COLDER WITH HIGHS ONLY IN THE 30S
BEHIND THE COLD FRONT.
THE UPPER LOW WILL BE TO THE EAST AND THERE WILL BE NORTHWEST FLOW
ACROSS THE AREA MONDAY THROUGH WEDNESDAY. THERE COULD BE SOME CLOUDS
AS A FEW WEAK UPPER LEVEL WAVES MOVE THROUGH THE AREA...BUT THERE IS
WARM ADVECTION AND TEMPERATURES SHOULD START TO WARM UP. DEPENDING
ON HOW MUCH SNOW THERE IS SATURDAY NIGHT INTO SUNDAY THE
TEMPERATURES MAY REMAIN A LITTLE COOLER FOR MONDAY...BUT WARM FOR
TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAF THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1159 AM CST WED MAR 6 2013
STRATUS TO THE WEST HAS HALTED THE EASTWARD PROGRESSION AND HAS
BEGUN TO ERODE. IT APPEARS THAT CEILINGS SHOULD BE VFR AND THAT
ANY ADDITIONAL CEILINGS SHOULD BE LIMITED TO LOCATIONS TO THE WEST
FOR THE OVERNIGHT. AS FOR LLWS...IT APPEARS LESS LIKELY THAT THIS
WILL BE AN ISSUE. SURFACE WIND SPEEDS SHOULD STAY UP A BIT TONIGHT
AS THE LOW-LEVEL JET DEVELOPS...AND WINDS ALOFT DO NOT APPEAR TO
BE QUITE AS STRONG AS ONCE SUSPECTED.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...JCB
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1210 PM CST WED MAR 6 2013
.AVIATION...
18Z TAFS FOR KOFK...KOMA AND KLNK.
AREA OF LOW CLOUDS ACROSS EASTERN NEBRASKA HAD DECREASED
RAPIDLY DURING THE LATE MORNING AND THIS TREND IS EXPECTED TO
CONTINUE EARLY IN THE PERIOD THIS AFTERNOON. BIG QUESTION WILL BE
WHETHER CLOUDS ROLL BACK IN AGAIN THIS EVENING SIMILAR TO LAST
NIGHT. MAY BE SOME POTENTIAL IN EASTERN AREAS ALONG THE MISSOURI
RIVER WHERE MORE EXTENSIVE CLOUDS IN PLACE ACROSS WESTERN IOWA BUT
WILL KEEP VFR CONDITIONS AT ALL THREE SITES FOR NOW AND SEE HOW
THINGS DEVELOP DURING THE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 354 AM CST WED MAR 6 2013/
DISCUSSION...
MAIN FORECAST CONCERN TODAY WILL BE THE EXTENT OF LOW CLOUDS AND
THE RESULTING AFFECT ON TEMPERATURES. THEN FOCUS TURNS TO SYSTEM
MOVING INTO THE PLAINS FOR THE WEEKEND.
AN EXPANSIVE AREA OF STRATUS CONTINUES TO MOVES SOUTH FROM THE
EASTERN DAKOTAS AND CURRENTLY COVERS MOST OF THE CWA EXCEPT THE
EXTREME WESTERN COUNTIES. THE RAP SEEMS TO HAVE THE BEST HANDLE
ON THESE CLOUDS AND WILL JUMP ON BOARD WITH THIS
GUIDANCE...KEEPING CLOUD COVER THROUGH AT LEAST 18Z OVER A
MAJORITY OF THE CWA. A SFC HIGH PRESSURE RIDGE CURRENTLY OVER
CENTRAL NEBRASKA WILL CONTINUE TO BUILD EAST AND INHIBIT MIXING
TO SCOUR OUT CLOUDS. THEREFORE THE RAP IDEA OF HANGING ONTO THE
CLOUDS SEEMS FAIR THROUGH MUCH OF THE MORNING HOURS AND POSSIBLY
INTO THE AFTERNOON IN OUR EAST. AS SOUTHERLY LOW LEVEL FLOW
INCREASES LATE THIS AFTERNOON...EXPECT CLOUDS TO MOVE OUT FROM
WEST TO EAST. HAVE REDUCED HIGHS TO A FEW DEGREES BELOW MOS DUE TO
CLOUD COVER.
QUIET CONDITIONS AND A GRADUAL WARMING TREND ARE EXPECTED TODAY
THROUGH FRIDAY AS AN UPPER RIDGE PASSES OVER THE CENTRAL CONUS
THROUGH THIS TIME PERIOD. HIGH TEMPS SHOULD BE IN THE UPPER 40S
AND LOWER 50S BY FRIDAY.
FOCUS TURNS TO LARGE SYSTEM CURRENTLY OFF THE PACIFIC NORTHWEST
COAST. THIS IS FORECAST TO ROUND THE FOUR CORNERS REGION BY
SATURDAY 12Z. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON
PLACEMENT AND TIMING LEADING TO INCREASING FORECASTER CONFIDENCE.
A LEAD SHORTWAVE WILL EJECT INTO THE CENTRAL PLAINS BY FRIDAY
NIGHT WITH A SFC WARM FRONT EXTENDING NORTHEAST AND BISECTING OUR
CWA. THIS BOUNDARY SHOULD BE THE FOCUS FOR PRECIPITATION FRIDAY
NIGHT INTO SATURDAY. BETTER UPPER LEVEL DYNAMICS WILL ADVANCE
INTO THE AREA SATURDAY NIGHT INTO SUNDAY AS THE UPPER LOW KICKS
OUT OF EASTERN COLORADO AND INTO KANSAS. WILL CONTINUE LIKELY POPS
FOR THIS TIME PERIOD. TIGHT BAROCLINIC ZONE WILL REMAIN EXTENDED
ACROSS THE FORECAST AREA WITH SNOW MOST LIKELY TO THE NORTH OF THE
BOUNDARY AND RAIN IN THE SOUTH...WITH A TRANSITION ZONE SOMEWHERE
IN THE MIDDLE. MODELS HAVE BEEN CONSISTENT WITH DROPPING COLDER
AIR SOUTH OVER THE FORECAST AREA SO SNOW COULD BE PRIMARY PCPN
TYPE SAT NIGHT THROUGH SUNDAY NIGHT WHEN DEFORMATION ZONE MOVES
OVERHEAD. HAVE INCREASED THE SFC WINDS ON THE BACKSIDE OF THIS
SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH UNIDIRECTIONAL
NORTHERLY FLOW CREATING QUITE BLUSTERY CONDITIONS. 850MB WIND
SPEEDS ARE FORECAST AROUND 50 KTS OFF BOTH THE 00Z GFS AND 00Z
ECMWF. THIS SAID...IF ANY SNOW IS FALLING...IT WILL BE BLOWING
AROUND.
THIS SYSTEM QUICKLY MOVES EAST SUNDAY NIGHT ENDING PCPN FROM WEST
TO EAST LEAVING NORTHWESTERLY FLOW ALOFT. FORECAST SUB ZERO C 850
MB TEMPS IN ADDITION TO POTENTIAL SNOW COVER WOULD SUGGEST BELOW
NORMAL TEMPS EARLY NEXT WEEK.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
FOBERT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 PM EST WED MAR 6 2013
.SYNOPSIS...
A POWERFUL LOW PRESSURE SYSTEM OVER COASTAL VIRGINIA WILL MOVE
OFFSHORE THROUGH TONIGHT. DRY HIGH PRESSURE WILL BUILD OVER THE
EASTERN SEABOARD THURSDAY THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
AS OF 235 PM WEDNESDAY...
THROUGH TONIGHT: IMPROVING WEATHER EXPECTED TONIGHT. LATEST SURFACE
MAP SHOWS THE STRONG SURFACE LOW NEAR THE MOUTH OF CHESAPEAKE BAY.
BANDS OF RAIN AND SNOW SHOWERS CONTINUE TO PIVOT AROUND THE LOW INTO
NORTHEAST NC... ALTHOUGH THUS FAR THIS AFTERNOON -- IN CONTRAST TO
THIS MORNING`S HRRR GUIDANCE -- THE SIGNIFICANT REFLECTIVITIES HAVE
HELD LARGELY NORTH AND EAST OF OUR FORECAST AREA. EXTRAPOLATION OF
EXISTING UPSTREAM PRECIP AND LOCAL WRF OUTPUT STILL SUPPORT PRECIP
WORKING ACROSS THE NORTHEAST CWA... ALONG AND NE OF A LINE FROM
OXFORD TO WILSON... FOR THE NEXT FEW HOURS. SURFACE WET BULBS ARE
GENERALLY ABOVE FREEZING IN THIS AREA... SO EXPECT A PTYPE OF MOSTLY
RAIN... ALTHOUGH HEAVIER BANDS MAY STILL MIX WITH A LITTLE
INCONSEQUENTIAL WET SNOW IN THE FAR NORTHEAST. THE LOW SWINGS
FARTHER OUT TO SEA THIS EVENING... LEAVING LITTLE MORE THAN PATCHY
SPRINKLES BEFORE THE PRECIP THREAT ENDS ENTIRELY BY MIDNIGHT.
REGARDING THE WINDS... WE`VE HAD NUMEROUS SITES ATTAIN PEAK GUSTS OF
40-46 MPH SO FAR TODAY WITH NEARLY ALL LOCATIONS SEEING 30 MPH GUSTS
OR GREATER. THE DEPARTURE OF THE COASTAL LOW AND SUBSEQUENT SLOW
SLACKENING OF THE MSLP GRADIENT AND GRADUAL DECREASE IN NEAR-SURFACE
MIXING WILL RESULT IN SLOWLY DECREASING WINDS AS WE GO THROUGH THE
EVENING. WILL LEAVE THE WIND ADVISORY IN PLACE UNTIL MIDNIGHT...
ALTHOUGH IT MAY NEED TO BE CANCELED A FEW HOURS EARLY. EXPECT
GRADUAL CLEARING SKIES FROM SW TO NORTHEAST AS WE DRY OUT IN THE
LOWEST FEW THOUSAND FEET. DESPITE DEW POINTS IN THE 20S THROUGH
TONIGHT... THE AIR SHOULD STAY JUST STIRRED ENOUGH NEAR THE GROUND
TO KEEP LOWS UP A BIT... 29-34.
FOR THURSDAY/THURSDAY NIGHT: WITH THE COLUMN DRYING OUT AND SINKING/
STABILIZING ALOFT... EXPECT QUITE A BIT OF SUNSHINE WITH PERHAPS
SOME FLAT AFTERNOON CUMULUS. SURFACE HIGH PRESSURE CENTERED OVER
ONTARIO AND THE UPPER MIDWEST/UPPER GREAT LAKES WILL EXTEND
SOUTHWARD WITH RIDGING BUILDING SLOWLY INTO NC FROM THE NW. WINDS
FROM THE NNW WILL NOT BE NEARLY AS STRONG AS THEY HAVE BEEN TODAY
BUT THE MSLP GRADIENT REMAINS TIGHT ENOUGH TO TRANSLATE INTO SURFACE
WINDS OF 10-15 KTS AND PERIODIC GUSTS TO 15-20 KTS BASED ON
PROJECTED WINDS IN THE UPPER PORTIONS OF THE MIXED LAYER. LOW LEVEL
THICKNESSES WILL BE AROUND 20-25 METERS BELOW NORMAL... SUGGESTING
HIGHS OF 51-58... OR ROUGHLY TWO CATEGORIES BELOW NORMAL. THE MID
LEVEL LOW NEAR LAKE SUPERIOR THIS MORNING WILL DROP TOWARD THE
SOUTHEAST OVER PA/DEL LATE THURSDAY NIGHT... HOWEVER THE LACK OF
MOISTURE AT ANY LEVEL AND NO OPPORTUNITY FOR AN MOISTURE TRANSPORT
INTO NC WITH LOW LEVEL FLOW FROM THE NNW WILL ALLOW SKIES TO STAY
GENERALLY CLEAR. LOWS 28-33 WITH 4-8 KTS OF WIND FROM THE NORTH.
-GIH
&&
.SHORT TERM /FRIDAY AND SUNDAY NIGHT/...
AS OF 250 PM WEDNESDAY...
AN OMEGA BLOCK WILL DEVELOP BY FRIDAY AS THE UPPER LOW OFF THE MID
ATLANTIC COAST CONTINUES TO WOBBLE SLOWLY TOWARD THE NORTH
ATLANTIC AND A CUTOFF LOW DEVELOPS OVER THE SOUTHWESTERN US.
MEANWHILE...A DISTURBANCE CURRENTLY MOVING INTO THE UPPER GREAT
LAKES AREA WILL BE DRAWN SOUTH ACROSS THE MID-ATLANTIC STATES AND
CLIP NORTHEASTERN NC EARLY FRIDAY. DEEP MOISTURE IS FORECAST TO BE
RATHER LIMITED...BUT ENHANCE CLOUD COVER OVER AT LEAST THE NORTHERN
COASTAL PLAIN SEEMS FAIRLY LIKELY WITH THE GLANCING BLOW OF THE VORT
MAX. FORECAST SOUNDINGS ALSO SHOW PERSISTENT BACKING OF THE LOW
LEVEL FLOW...WITH 10-15KT SURFACE WIND...SUGGESTING ANOTHER SURGE OF
COLD ADVECTION BEFORE HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES
FRIDAY NIGHT. THUS...WILL KEEP HIGHS A GOOD 4-6 DEGREES BELOW MOST
GUIDANCE ON FRIDAY...49-55 NORTHEAST TO SOUTHWEST. LOWS FRIDAY
NIGHT IN THE UPPER 20S TO LOWER 30S.
RIDGING ALOFT WILL BUILD OVER HEAD SATURDAY THROUGH SUNDAY...WHILE
SURFACE HIGH PRESSURE SETTLES ALONG THE EAST COAST. THIS WILL LEAD
TO A MODERATING TREND IN TEMPS AS 850MB TEMPS APPROACH 10C AND LOW
LEVEL THICKNESSES RISE ABOVE 1350M BY SUNDAY.
HOWEVER...NORTHEASTERLY LOW LEVEL FLOW IS FORECAST
TO CONTINUE SATURDAY...SO THE WARMING ALOFT MAY NOT BE COMPLETELY
REALIZED FOR YET ANOTHER DAY. THE MORE NOTICEABLE WARMUP WILL BE
FELT IN THE NORTHEAST CWA ON SATURDAY...WITH HIGHS RANGING FROM THE
MID 50S NORTHEAST TO AROUND 60 SOUTHWEST. THE SURFACE HIGH IS
FORECAST TO SHIFT OFFSHORE BY SUNDAY...AND IF THIS OCCURS...THEN
WEAK RETURN FLOW WOULD DEVELOP AND HELP PUSH HIGHS INTO THE MID
60S. DRY CONDITIONS WILL PERSIST BENEATH THE RIDGE.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 250 PM WEDNESDAY...
THE OMEGA BLOCK OVER THE CONUS IS FORECAST TO WEAKEN BY
MONDAY..ALLOWING AN UPPER LOW OVER THE SOUTHWESTERN US TO EJECT
EASTWARD ACROSS THE SOUTHERN PLAINS AND DEAMPLIFY AS IT LIFTS TOWARD
THE MIDWEST STATES . SOUTHERLY RETURN FLOW AHEAD OF THE SYSTEM
SHOULD PUSH TEMPS WELL ABOVE NORMAL MONDAY WITH LOW LEVEL THICKNESSES
PROGGED TO APPROACH 1360M. BASED ON THIS...UPPER 60S SEEM LIKELY
AND LOWER 70S POSSIBLE UNLESS CLOUD COVER IS MORE ROBUST THAN
FORECAST. AS THE UPPER TROUGH AND PRIMARY SURFACE LOW LIFT ACROSS
THE MIDWEST AND OH VALLEY...THE ATTENDANT COLD FRONT IS EXPECTED TO
MOVE CROSS THE MOUNTAINS MONDAY NIGHT/TUESDAY. THE GFS AND ECMWF
HAVE WAVERED BACK AND FORTH A BIT REGARDING THE EXACT TIMING OF THE
FRONTAL PASSAGE AND SENSIBLE WEATHER...BUT THEIR SOLUTIONS ARE
GENERALLY WITHIN 12 HOURS OF EACH OTHER. HOWEVER...THERE ARE STILL
ENOUGH DIFFERENCES IN THE MASS FIELDS TO KEEP POPS BELOW 50 PERCENT
AT THIS TIME. SHOULD ALSO NOTE THAT AS WE MOVE FURTHER INTO
MARCH...THIS TYPE OF PATTERN WILL BRING A BETTER CHANCE OF
THUNDERSTORMS ACCOMPANYING THE COLD FRONT...BUT WE WILL HOLD OFF ON
INCLUDING THUNDER IN THE FORECAST UNTIL TIMING OF THE SYSTEM AND
MOISTURE RETURN ARE MORE CERTAIN.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 1230 PM WEDNESDAY...
VFR CONDITIONS ARE EXPECTED TO PERSIST AT INT/GSO/FAY WELL INTO
WEDNESDAY. RDU/RWI WILL REMAIN CLOSER TO THE LOW CLOUD SHIELD (MVFR
TO HIGH-END IFR CIGS) ASSOCIATED WITH THE STRONG STORM CENTERED OVER
THE SE COAST OF VA... SO A PERIOD OF MVFR CIGS AND BRIEF MVFR VSBYS
WITHIN LIGHT RAIN SHOWERS (POSSIBLY MIXED WITH WET SNOW) ARE
POSSIBLE THIS AFTERNOON UNTIL 23Z-01Z. AS THIS STORM SYSTEM HEADS
OFF THE COAST THIS EVENING... SKIES WILL CLEAR OUT SW TO NE. STRONG
WINDS COMING FROM THE WEST AND NW WILL REMAIN AN AVIATION HAZARD
THROUGH EARLY TO MID EVENING... PRESENTING A SIGNIFICANT CROSSWIND
PRIMARILY AT GSO/RDU/RWI/FAY. SUSTAINED WINDS OF 15-25 KTS AND GUSTS
TO 30-38 KTS ARE EXPECTED THROUGH 22Z... THEN NW WINDS WILL BE
DIMINISHING THROUGH THE EVENING AS THEY BECOME NORTHERLY. UNLIMITED
SKIES AND NORTH WINDS 7-12 KTS ARE EXPECTED AFTER SUNRISE THURSDAY.
LOOKING BEYOND 18Z THURSDAY... VFR CONDITIONS WILL DOMINATE THROUGH
EARLY FRIDAY. BRIEF MVFR CIGS ARE POSSIBLE FRIDAY AFTERNOON INTO
FRIDAY NIGHT AS LOW PRESSURE MOVES BY TO OUR NORTHEAST. THEN AS A
STORM SYSTEM APPROACHES FROM THE WEST... IFR CIGS ARE POSSIBLE EARLY
MONDAY MORNING... LIFTING TO VFR BY MONDAY AFTERNOON.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...SMITH
LONG TERM...SMITH
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
235 PM EST WED MAR 6 2013
.SYNOPSIS...
A POWERFUL LOW PRESSURE SYSTEM OVER COASTAL VIRGINIA WILL MOVE
OFFSHORE THROUGH TONIGHT. DRY HIGH PRESSURE WILL BUILD OVER THE
EASTERN SEABOARD THURSDAY THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
AS OF 235 PM WEDNESDAY...
THROUGH TONIGHT: IMPROVING WEATHER EXPECTED TONIGHT. LATEST SURFACE
MAP SHOWS THE STRONG SURFACE LOW NEAR THE MOUTH OF CHESAPEAKE BAY.
BANDS OF RAIN AND SNOW SHOWERS CONTINUE TO PIVOT AROUND THE LOW INTO
NORTHEAST NC... ALTHOUGH THUS FAR THIS AFTERNOON -- IN CONTRAST TO
THIS MORNING`S HRRR GUIDANCE -- THE SIGNIFICANT REFLECTIVITIES HAVE
HELD LARGELY NORTH AND EAST OF OUR FORECAST AREA. EXTRAPOLATION OF
EXISTING UPSTREAM PRECIP AND LOCAL WRF OUTPUT STILL SUPPORT PRECIP
WORKING ACROSS THE NORTHEAST CWA... ALONG AND NE OF A LINE FROM
OXFORD TO WILSON... FOR THE NEXT FEW HOURS. SURFACE WET BULBS ARE
GENERALLY ABOVE FREEZING IN THIS AREA... SO EXPECT A PTYPE OF MOSTLY
RAIN... ALTHOUGH HEAVIER BANDS MAY STILL MIX WITH A LITTLE
INCONSEQUENTIAL WET SNOW IN THE FAR NORTHEAST. THE LOW SWINGS
FARTHER OUT TO SEA THIS EVENING... LEAVING LITTLE MORE THAN PATCHY
SPRINKLES BEFORE THE PRECIP THREAT ENDS ENTIRELY BY MIDNIGHT.
REGARDING THE WINDS... WE`VE HAD NUMEROUS SITES ATTAIN PEAK GUSTS OF
40-46 MPH SO FAR TODAY WITH NEARLY ALL LOCATIONS SEEING 30 MPH GUSTS
OR GREATER. THE DEPARTURE OF THE COASTAL LOW AND SUBSEQUENT SLOW
SLACKENING OF THE MSLP GRADIENT AND GRADUAL DECREASE IN NEAR-SURFACE
MIXING WILL RESULT IN SLOWLY DECREASING WINDS AS WE GO THROUGH THE
EVENING. WILL LEAVE THE WIND ADVISORY IN PLACE UNTIL MIDNIGHT...
ALTHOUGH IT MAY NEED TO BE CANCELED A FEW HOURS EARLY. EXPECT
GRADUAL CLEARING SKIES FROM SW TO NORTHEAST AS WE DRY OUT IN THE
LOWEST FEW THOUSAND FEET. DESPITE DEW POINTS IN THE 20S THROUGH
TONIGHT... THE AIR SHOULD STAY JUST STIRRED ENOUGH NEAR THE GROUND
TO KEEP LOWS UP A BIT... 29-34.
FOR THURSDAY/THURSDAY NIGHT: WITH THE COLUMN DRYING OUT AND SINKING/
STABILIZING ALOFT... EXPECT QUITE A BIT OF SUNSHINE WITH PERHAPS
SOME FLAT AFTERNOON CUMULUS. SURFACE HIGH PRESSURE CENTERED OVER
ONTARIO AND THE UPPER MIDWEST/UPPER GREAT LAKES WILL EXTEND
SOUTHWARD WITH RIDGING BUILDING SLOWLY INTO NC FROM THE NW. WINDS
FROM THE NNW WILL NOT BE NEARLY AS STRONG AS THEY HAVE BEEN TODAY
BUT THE MSLP GRADIENT REMAINS TIGHT ENOUGH TO TRANSLATE INTO SURFACE
WINDS OF 10-15 KTS AND PERIODIC GUSTS TO 15-20 KTS BASED ON
PROJECTED WINDS IN THE UPPER PORTIONS OF THE MIXED LAYER. LOW LEVEL
THICKNESSES WILL BE AROUND 20-25 METERS BELOW NORMAL... SUGGESTING
HIGHS OF 51-58... OR ROUGHLY TWO CATEGORIES BELOW NORMAL. THE MID
LEVEL LOW NEAR LAKE SUPERIOR THIS MORNING WILL DROP TOWARD THE
SOUTHEAST OVER PA/DEL LATE THURSDAY NIGHT... HOWEVER THE LACK OF
MOISTURE AT ANY LEVEL AND NO OPPORTUNITY FOR AN MOISTURE TRANSPORT
INTO NC WITH LOW LEVEL FLOW FROM THE NNW WILL ALLOW SKIES TO STAY
GENERALLY CLEAR. LOWS 28-33 WITH 4-8 KTS OF WIND FROM THE NORTH.
-GIH
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 AM WEDNESDAY...
FRIDAY AND FRIDAY NIGHT:
VERTICALLY STACKED LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO
HANG AROUND SEVERAL HUNDRED MILES OFF THE MID ATLANTIC COAST ON
FRIDAY... BEFORE PICKING UP SOME EAST/EAST-SOUTHEASTWARD MOMENTUM ON
FRIDAY NIGHT AS ADDITIONAL S/W ENERGY IN THE FORM OF A BIT WEAKER
CLOSED LOW DIVES SOUTHEASTWARD FROM THE GREAT LAKES REGION THURSDAY
NIGHT INTO FRIDAY (BEFORE BEING ABSORBED BY THE DEEP CYCLONIC VORTEX
OFF THE MID ATLANTIC COAST LATE FRIDAY INTO FRIDAY NIGHT). THIS
ADDITIONAL ENERGY HAS TRENDED A BIT FURTHER WESTWARD WITH ITS
TRACK... YET STILL EXPECTED TO ONLY SIDE SWIPE OUR COASTAL PLAIN AND
NORTHEASTERN PIEDMONT COUNTIES FRIDAY INTO FRIDAY EVENING. GIVEN THE
OVERALL LACK OF MOISTURE EXPECTED ACROSS OUR AREA AND THE CURRENT
TRACK OF THE DISTURBANCE EXPECT WE SHOULD REMAIN DRY... WITH ONLY A
POSSIBLE INCREASE IN SOME CLOUD COVER ON FRIDAY AFTERNOON INTO THE
EVENING ACROSS EASTERN PORTIONS OF CENTRAL NC. HOWEVER... THE CLOUD
COVER COULD HAVE AN IMPACT ON HIGH TEMPERATURES FOR FRIDAY ACROSS
EASTERN/NORTHEASTERN PORTIONS OF THE RAH CWA. PLAN TO GO ON THE
COOLER SIDE OF GUIDANCE FOR MOST OF THE AREA AGAIN GIVEN THIS ALONG
WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO RUN SOME 20 TO
30 METERS BELOW NORMAL FOR THIS TIME OF YEAR... PLUS A POSSIBLE SNOW
PACK TO THE NORTH OF THE CWA WITH CONTINUED NORTH-NORTHWESTERLY LOW
LEVEL FLOW. THIS YIELDS HIGH TEMPS FROM AROUND 50 NE TO THE UPPER
50S SW. IN ADDITION TO THE CHILLY TEMPS... EXPECT WE SHOULD CONTINUE
TO HAVE WINDS IN THE 10 TO 15 MPH RANGE... WITH GUSTS AS HIGH AS 25
MPH.
ANY CLOUD COVER ASSOCIATED WITH THE AFOREMENTIONED DISTURBANCE
SHOULD BEGIN TO SHIFT TO THE EAST OF THE AREA... WITH SUBSIDENCE IN
THE WAKE OF THE DISTURBANCE (NAM WOULD SUGGEST A BIT SLOWER TIMING
BUT APPEARS TO BE A SLOW OUTLIER WRT THE TIMING OF THE DISTURBANCE).
WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA AND CLEARING SKIES
EXPECT WE WILL SEE TEMPS FALL INTO THE UPPER 20S TO LOWER 30S FOR
LOWS SATURDAY MORNING... WITH A LIGHT NORTH-NORTHWESTERLY BREEZE
OVERNIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...
S/W RIDGING IS EXPECTED TO BUILD ACROSS THE REGION FOR THE
WEEKEND... WHILE SURFACE HIGH PRESSURE MOVES ACROSS THE AREA AND
OFFSHORE. THIS WILL RESULT IN QUITE WEATHER ACROSS CENTRAL NC THIS
WEEKEND... WITH A WARMING TREND. EXPECT HIGH TEMPS ON SATURDAY WILL
BE IN THE MID TO UPPER 50S... WITH MAYBE A FEW LOCATIONS TOUCHING 60
ACROSS THE FAR SOUTH OR SOUTHWEST WITH MOSTLY SUNNY SKIES. HIGH
SUNDAY ARE EXPECTED TO BE EVEN WARMER... AS AFTERNOON LOW LEVEL
THICKNESS VALUES ARE EXPECTED TO FINALLY BE SLIGHTLY ABOVE NORMAL.
THUS... EXPECT HIGH TEMPS WILL WARM INTO THE LOWER TO MID 60S BY
SUNDAY AFTERNOON WITH INCREASING HIGH LEVEL CLOUD COVER. LOWS SUNDAY
MORNING ARE EXPECTED TO BE IN THE LOWER TO MID 30S... WITH EXCELLENT
RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT AND
VARIABLE TO CALM WINDS AS HIGH PRESSURE ALOFT AND THE SURFACE WILL
SETTLE OVER THE AREA.
THE NEXT SYSTEM IS EXPECTED TO MOVE INTO THE AREA EARLY NEXT WEEK AS
A DEEP TROUGH AND ASSOCIATED COLD FRONT SHIFT EASTWARD AND
EVENTUALLY ACROSS THE REGION. THE OPERATIONAL GFS AND ECMWF HAVE
COME INTO MUCH BETTER AGREEMENT ON THE TIMING OF THE SYSTEM... AND
NOW BOTH SHOW AT LEAST SOME PHASING/INTERACTION OF THIS SYSTEM
(WHICH ORIGINATES FROM A CLOSED LOW IN THE SOUTHWESTERN U.S. LATE
THIS WEEK) WITH A NORTHERN STREAM TROUGH. BOTH THE 00Z ECMWF AND 00Z
GFS SHOW AN AREA OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS MOVING
ACROSS THE AREA LATE MONDAY AFTERNOON INTO TUESDAY MORNING... ALONG
WITH THE PASSAGE OF A STRONG COLD FRONT BY TUESDAY MORNING. WPC
(FORMERLY KNOW AS HPC... NOW THE WEATHER PREDICTION CENTER) PREFERS
A BIT SLOWER TIMING... LAGGING THE TIMING OF THE FRONT AND CONTINUED
CHANCES FOR SHOWERS AND POSSIBLY STORMS INTO THE DAY TUESDAY... AS
THEY PREFER THE EUROPEAN CENTRE ENSEMBLE MEAN AS THEY NOTED IT
OUTSTANDING PERFORMANCE WITH THE SYNOPTIC FLOW OF LATE. THUS... WILL
TREND THE TIMING A BIT SLOWER THAN THE CURRENT OPERATIONAL MODELS
ADVERTISE... WITH A GOOD CHANCE OF RAIN STILL LATE MONDAY INTO
TUESDAY MORNING. EXPECT HIGHS TO BE IN THE 60S TO POSSIBLY 70S EAST
MONDAY... WITH UPPER 50S TO 60S TUESDAY (HIGHLY DEPENDENT ON THE
TIMING OF THE FRONT). LOWS EARLY NEXT WEEK ARE EXPECTED TO BE IN THE
40S TO EVEN AROUND 50 ON TUESDAY MORNING (AGAIN TIED TO THE EVENTUAL
TIMING OF THE FRONT).
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 1230 PM WEDNESDAY...
VFR CONDITIONS ARE EXPECTED TO PERSIST AT INT/GSO/FAY WELL INTO
WEDNESDAY. RDU/RWI WILL REMAIN CLOSER TO THE LOW CLOUD SHIELD (MVFR
TO HIGH-END IFR CIGS) ASSOCIATED WITH THE STRONG STORM CENTERED OVER
THE SE COAST OF VA... SO A PERIOD OF MVFR CIGS AND BRIEF MVFR VSBYS
WITHIN LIGHT RAIN SHOWERS (POSSIBLY MIXED WITH WET SNOW) ARE
POSSIBLE THIS AFTERNOON UNTIL 23Z-01Z. AS THIS STORM SYSTEM HEADS
OFF THE COAST THIS EVENING... SKIES WILL CLEAR OUT SW TO NE. STRONG
WINDS COMING FROM THE WEST AND NW WILL REMAIN AN AVIATION HAZARD
THROUGH EARLY TO MID EVENING... PRESENTING A SIGNIFICANT CROSSWIND
PRIMARILY AT GSO/RDU/RWI/FAY. SUSTAINED WINDS OF 15-25 KTS AND GUSTS
TO 30-38 KTS ARE EXPECTED THROUGH 22Z... THEN NW WINDS WILL BE
DIMINISHING THROUGH THE EVENING AS THEY BECOME NORTHERLY. UNLIMITED
SKIES AND NORTH WINDS 7-12 KTS ARE EXPECTED AFTER SUNRISE THURSDAY.
LOOKING BEYOND 18Z THURSDAY... VFR CONDITIONS WILL DOMINATE THROUGH
EARLY FRIDAY. BRIEF MVFR CIGS ARE POSSIBLE FRIDAY AFTERNOON INTO
FRIDAY NIGHT AS LOW PRESSURE MOVES BY TO OUR NORTHEAST. THEN AS A
STORM SYSTEM APPROACHES FROM THE WEST... IFR CIGS ARE POSSIBLE EARLY
MONDAY MORNING... LIFTING TO VFR BY MONDAY AFTERNOON.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...BSD
LONG TERM...BSD
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1230 PM EST WED MAR 6 2013
.SYNOPSIS...
A POWERFUL LOW PRESSURE SYSTEM OVER SOUTHEAST VIRGINIA WILL MOVE
SLOWLY EAST OUT OVER THE ATLANTIC LATER TODAY THROUGH TONIGHT. DRY
HIGH PRESSURE WILL SLOWLY BUILD OVER THE EASTERN SEABOARD THURSDAY
THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
AS OF 955 AM WEDNESDAY...
REST OF TODAY: STRONG GRADIENT WINDS AND THE CHANCE OF SNOW SHOWERS
OVER NORTH CENTRAL SECTIONS REMAIN SIGNIFICANT FORECAST CONCERNS.
LATEST SURFACE MAP SHOWS THE SURFACE LOW CENTER JUST NORTH OF
WILLIAMSBURG VA. MOSTLY LIGHT SNOW SHOWERS... OCCASIONALLY CHANGING
BACK TO RAIN WHEN RATES DECREASE... CONTINUE TO PIVOT OVER THE FAR
NORTH CENTRAL AND NORTHEAST CWA. WE`VE RECEIVED A FEW REPORTS OF
LIGHT ACCUMULATION ON GRASSY AREAS FROM A FEW SPOTS THIS MORNING...
AND THIS SEEMS TO HAVE BEEN THE CASE BENEATH THE AREAS OF HEAVIER
REFLECTIVITIES... ONE BAND OF WHICH IS PROGRESSING THROUGH FRANKLIN
TOWARD NASH COUNTY. WE ARE STILL CANVASSING THE COUNTIES AND TOWNS
THERE TO DETERMINE THE DEGREE OF IMPACT OF THE SNOW THAT HAS FALLEN
SO FAR... BUT BASED ON THE RADAR TRENDS AND RECENT HRRR RUNS WHICH
SUGGEST THAT SOME OF THE HEAVIER SNOW SHOWERS OVER SOUTH CENTRAL VA
MAY TRACK SOUTH OF THE BORDER... A SHORT-TERM ADVISORY MAY BE NEEDED
HERE. IN ANY CASE... BASED ON THE OBSERVED AND EXPECTED WET BULB
TEMPS THAT SHOULD HOLD VERY CLOSE TO FREEZING OR JUST ABOVE... AND
WITH FAIRLY MILD ROAD TEMPS... ROADS SHOULD BE JUST WET WITH ANY
ACCUMULATION ON THE GRASSY AREAS ONLY. WILL CONTINUE TO MONITOR. THE
WIND ADVISORY WILL REMAIN AS IS. SEVERAL GUSTS OVER 30 KTS HAVE
ALREADY BEEN REPORTED... PRIMARILY IN LOCATIONS THAT HAVE SEEN SOME
SUNSHINE THIS MORNING... IN THE FAR WEST AND ACROSS THE SOUTHERN
CWA. OBSERVED 925 MB TEMPS FROM UPPER AIR SOUNDINGS ARE AROUND 30
KTS... AND AROUND 35-40 KT AT 850 MB... SO WITH GOOD MIXING EXPECT
FREQUENT GUSTS TO AROUND 35-45 MPH. HIGHS FROM 36-40 NORTH TO AROUND
50 IN THE SOUTH. -GIH
TONIGHT...SHOULD SEE PRECIP CHANCES END EARLY IN THE FAR NE AS THE
LOW PRESSURE SYSTEM PULLS FARTHER AWAY. CLEARING SKIES WILL TREND
EWD DURING THE NIGHT. DUE TOT HE LARGE WIND FIELD ASSOCIATED WITH
THE SYSTEM...EXPECT WINDY/BREEZY CONDITIONS TO PERSIST THROUGH MOST
OF THE NIGHT. THIS MIXING WILL PREVENT TEMPS FROM REACHING THEIR
FULL COOLING POTENTIAL. MIN TEMPS INT HE 30-35 DEGREE RANGE.
THURSDAY...WE WILL REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW
THOUGH THE ASSOCIATED SUBSIDENCE ON THE BACK SIDE SHOULD MAINTAIN
CLEAR SKIES OVER MOST OF THE REGION. NLY WINDS WILL GUSTS TO AROUND
25 KTS...ESPECIALLY IN THE MORNING...AND MAINLY EAST OF HIGHWAY 1.
850MB THERMAL TROUGH AND ASSOCIATED LOW LEVEL CAA WILL PERSIST
THROUGH THU. THIS YIELDS LOW LEVEL THICKNESSES ABOUT 25M BELOW
NORMAL. THIS WOULD SUGGEST MAX TEMPS ABOUT 6-9 DEGREES BELOW NORMAL.
FAVOR MAX TEMPS ABOUT 4 DEGREES BELOW GUIDANCE...RANGING FROM NEAR
50 FAR NE TO THE MID 50S SOUTH.
THURSDAY NIGHT...SURFACE HIGH PRESSURE WILL BEGIN TO INFLUENCE OUR
SENSIBLE WEATHER. PRESSURE GRADIENT ANALYSIS SUGGEST SOME POTENTIAL
FOR A LIGHT WIND THROUGH THE NIGHT. IF SFC WIND ABLE TO
DECOUPLE...COULD SEE TEMPS FALL ABOUT 3-4 DEGREES COOLER THAN
CURRENTLY FORECAST. FOR NOW...WILL MAINTAIN MIN TEMPS NEAR 30 TO
LOWER 30S. -WSS
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 AM WEDNESDAY...
FRIDAY AND FRIDAY NIGHT:
VERTICALLY STACKED LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO
HANG AROUND SEVERAL HUNDRED MILES OFF THE MID ATLANTIC COAST ON
FRIDAY... BEFORE PICKING UP SOME EAST/EAST-SOUTHEASTWARD MOMENTUM ON
FRIDAY NIGHT AS ADDITIONAL S/W ENERGY IN THE FORM OF A BIT WEAKER
CLOSED LOW DIVES SOUTHEASTWARD FROM THE GREAT LAKES REGION THURSDAY
NIGHT INTO FRIDAY (BEFORE BEING ABSORBED BY THE DEEP CYCLONIC VORTEX
OFF THE MID ATLANTIC COAST LATE FRIDAY INTO FRIDAY NIGHT). THIS
ADDITIONAL ENERGY HAS TRENDED A BIT FURTHER WESTWARD WITH ITS
TRACK... YET STILL EXPECTED TO ONLY SIDE SWIPE OUR COASTAL PLAIN AND
NORTHEASTERN PIEDMONT COUNTIES FRIDAY INTO FRIDAY EVENING. GIVEN THE
OVERALL LACK OF MOISTURE EXPECTED ACROSS OUR AREA AND THE CURRENT
TRACK OF THE DISTURBANCE EXPECT WE SHOULD REMAIN DRY... WITH ONLY A
POSSIBLE INCREASE IN SOME CLOUD COVER ON FRIDAY AFTERNOON INTO THE
EVENING ACROSS EASTERN PORTIONS OF CENTRAL NC. HOWEVER... THE CLOUD
COVER COULD HAVE AN IMPACT ON HIGH TEMPERATURES FOR FRIDAY ACROSS
EASTERN/NORTHEASTERN PORTIONS OF THE RAH CWA. PLAN TO GO ON THE
COOLER SIDE OF GUIDANCE FOR MOST OF THE AREA AGAIN GIVEN THIS ALONG
WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO RUN SOME 20 TO
30 METERS BELOW NORMAL FOR THIS TIME OF YEAR... PLUS A POSSIBLE SNOW
PACK TO THE NORTH OF THE CWA WITH CONTINUED NORTH-NORTHWESTERLY LOW
LEVEL FLOW. THIS YIELDS HIGH TEMPS FROM AROUND 50 NE TO THE UPPER
50S SW. IN ADDITION TO THE CHILLY TEMPS... EXPECT WE SHOULD CONTINUE
TO HAVE WINDS IN THE 10 TO 15 MPH RANGE... WITH GUSTS AS HIGH AS 25
MPH.
ANY CLOUD COVER ASSOCIATED WITH THE AFOREMENTIONED DISTURBANCE
SHOULD BEGIN TO SHIFT TO THE EAST OF THE AREA... WITH SUBSIDENCE IN
THE WAKE OF THE DISTURBANCE (NAM WOULD SUGGEST A BIT SLOWER TIMING
BUT APPEARS TO BE A SLOW OUTLIER WRT THE TIMING OF THE DISTURBANCE).
WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA AND CLEARING SKIES
EXPECT WE WILL SEE TEMPS FALL INTO THE UPPER 20S TO LOWER 30S FOR
LOWS SATURDAY MORNING... WITH A LIGHT NORTH-NORTHWESTERLY BREEZE
OVERNIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...
S/W RIDGING IS EXPECTED TO BUILD ACROSS THE REGION FOR THE
WEEKEND... WHILE SURFACE HIGH PRESSURE MOVES ACROSS THE AREA AND
OFFSHORE. THIS WILL RESULT IN QUITE WEATHER ACROSS CENTRAL NC THIS
WEEKEND... WITH A WARMING TREND. EXPECT HIGH TEMPS ON SATURDAY WILL
BE IN THE MID TO UPPER 50S... WITH MAYBE A FEW LOCATIONS TOUCHING 60
ACROSS THE FAR SOUTH OR SOUTHWEST WITH MOSTLY SUNNY SKIES. HIGH
SUNDAY ARE EXPECTED TO BE EVEN WARMER... AS AFTERNOON LOW LEVEL
THICKNESS VALUES ARE EXPECTED TO FINALLY BE SLIGHTLY ABOVE NORMAL.
THUS... EXPECT HIGH TEMPS WILL WARM INTO THE LOWER TO MID 60S BY
SUNDAY AFTERNOON WITH INCREASING HIGH LEVEL CLOUD COVER. LOWS SUNDAY
MORNING ARE EXPECTED TO BE IN THE LOWER TO MID 30S... WITH EXCELLENT
RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT AND
VARIABLE TO CALM WINDS AS HIGH PRESSURE ALOFT AND THE SURFACE WILL
SETTLE OVER THE AREA.
THE NEXT SYSTEM IS EXPECTED TO MOVE INTO THE AREA EARLY NEXT WEEK AS
A DEEP TROUGH AND ASSOCIATED COLD FRONT SHIFT EASTWARD AND
EVENTUALLY ACROSS THE REGION. THE OPERATIONAL GFS AND ECMWF HAVE
COME INTO MUCH BETTER AGREEMENT ON THE TIMING OF THE SYSTEM... AND
NOW BOTH SHOW AT LEAST SOME PHASING/INTERACTION OF THIS SYSTEM
(WHICH ORIGINATES FROM A CLOSED LOW IN THE SOUTHWESTERN U.S. LATE
THIS WEEK) WITH A NORTHERN STREAM TROUGH. BOTH THE 00Z ECMWF AND 00Z
GFS SHOW AN AREA OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS MOVING
ACROSS THE AREA LATE MONDAY AFTERNOON INTO TUESDAY MORNING... ALONG
WITH THE PASSAGE OF A STRONG COLD FRONT BY TUESDAY MORNING. WPC
(FORMERLY KNOW AS HPC... NOW THE WEATHER PREDICTION CENTER) PREFERS
A BIT SLOWER TIMING... LAGGING THE TIMING OF THE FRONT AND CONTINUED
CHANCES FOR SHOWERS AND POSSIBLY STORMS INTO THE DAY TUESDAY... AS
THEY PREFER THE EUROPEAN CENTRE ENSEMBLE MEAN AS THEY NOTED IT
OUTSTANDING PERFORMANCE WITH THE SYNOPTIC FLOW OF LATE. THUS... WILL
TREND THE TIMING A BIT SLOWER THAN THE CURRENT OPERATIONAL MODELS
ADVERTISE... WITH A GOOD CHANCE OF RAIN STILL LATE MONDAY INTO
TUESDAY MORNING. EXPECT HIGHS TO BE IN THE 60S TO POSSIBLY 70S EAST
MONDAY... WITH UPPER 50S TO 60S TUESDAY (HIGHLY DEPENDENT ON THE
TIMING OF THE FRONT). LOWS EARLY NEXT WEEK ARE EXPECTED TO BE IN THE
40S TO EVEN AROUND 50 ON TUESDAY MORNING (AGAIN TIED TO THE EVENTUAL
TIMING OF THE FRONT).
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 1230 PM WEDNESDAY...
VFR CONDITIONS ARE EXPECTED TO PERSIST AT INT/GSO/FAY WELL INTO
WEDNESDAY. RDU/RWI WILL REMAIN CLOSER TO THE LOW CLOUD SHIELD (MVFR
TO HIGH-END IFR CIGS) ASSOCIATED WITH THE STRONG STORM CENTERED OVER
THE SE COAST OF VA... SO A PERIOD OF MVFR CIGS AND BRIEF MVFR VSBYS
WITHIN LIGHT RAIN SHOWERS (POSSIBLY MIXED WITH WET SNOW) ARE
POSSIBLE THIS AFTERNOON UNTIL 23Z-01Z. AS THIS STORM SYSTEM HEADS
OFF THE COAST THIS EVENING... SKIES WILL CLEAR OUT SW TO NE. STRONG
WINDS COMING FROM THE WEST AND NW WILL REMAIN AN AVIATION HAZARD
THROUGH EARLY TO MID EVENING... PRESENTING A SIGNIFICANT CROSSWIND
PRIMARILY AT GSO/RDU/RWI/FAY. SUSTAINED WINDS OF 15-25 KTS AND GUSTS
TO 30-38 KTS ARE EXPECTED THROUGH 22Z... THEN NW WINDS WILL BE
DIMINISHING THROUGH THE EVENING AS THEY BECOME NORTHERLY. UNLIMITED
SKIES AND NORTH WINDS 7-12 KTS ARE EXPECTED AFTER SUNRISE THURSDAY.
LOOKING BEYOND 18Z THURSDAY... VFR CONDITIONS WILL DOMINATE THROUGH
EARLY FRIDAY. BRIEF MVFR CIGS ARE POSSIBLE FRIDAY AFTERNOON INTO
FRIDAY NIGHT AS LOW PRESSURE MOVES BY TO OUR NORTHEAST. THEN AS A
STORM SYSTEM APPROACHES FROM THE WEST... IFR CIGS ARE POSSIBLE EARLY
MONDAY MORNING... LIFTING TO VFR BY MONDAY AFTERNOON.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD/WSS
SHORT TERM...BSD
LONG TERM...BSD
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
350 PM CST WED MAR 6 2013
.DISCUSSION.../ISSUED AT 350 PM CST/
CHALLENGES TONIGHT AND TOMORROW FOCUS ON STRATUS...OR POSSIBLY A
LACK THERE OF. THIS IS NOT AN EASY ONE TO ANSWER TONIGHT AS THE
STRATUS IS QUICKLY ERODING FROM THE SOUTHWEST TODAY AND WITH AN
INCREASED SOUTHERLY GRADIENT OVERNIGHT INDICATIONS ARE THAT IT MAY
REMAIN AT BAY IN LOCATIONS WHERE IT ERODES. HOWEVER...IF SOME OF
THESE BETTER WINDS ALOFT DO NOT MIX DOWN AN ALREADY STRONG INVERSION
MAY GET A LITTLE STRONGER THROUGH THE NIGHT ALLOWING STRATUS TO
REDEVELOP FROM THE EAST AND SOUTHEAST. SO REALLY COULD SEE EITHER
SOLUTION OCCURRING. SO...BECAUSE OF A LACK OF CONFIDENCE WILL NOT
CHANGE LOWS MUCH BUT IF THE FAR EASTERN CWA REMAINS CLOUDY ALL NIGHT
THE LOWS WILL PROBABLY BE A LITTLE WARMER THAN FORECAST.
A BIT BREEZY ON THURSDAY AS THE WINDS PICK UP FROM THE SOUTHEAST.
WILL KEEP TEMPERATURES IN THE LOWER TO MIDDLE 30S OVER EXISTING SNOW
COVER WHILE AREAS WITH NO SNOW IN SOUTH CENTRAL SOUTH DAKOTA SHOULD
EASILY REACH THE MID 40S. /08
THURSDAY NIGHT AND FRIDAY SHOULD BE RELATIVELY MILD WITH MOST OF THE
CLOUD INCREASE AHEAD OF APPROACHING SYSTEM COMING VERY LATE
THURSDAY NIGHT AND FRIDAY. AT THIS TIME DO NOT SEE PRECIPITATION
DEVELOPING UNTIL EARLY FRIDAY EVENING...BUT IT COULD DEVELOP RAPIDLY
AT THAT TIME. THE PRESENCE OF A STRENGTHENING FRONTAL BOUNDARY...
MOISTURE ADVECTION...AND DESTABILIZATION IS EXPECTED TO BRING
SHOWERY RAINS AND MAYBE EVEN THUNDERSTORMS SOUTHEAST...WITH LESS
CONVECTIVE BUT STILL VARIABLY INTENSITY PRECIPITATION NORTHWEST.
WARMING AHEAD OF THIS SYSTEM SHOULD PRECLUDE SNOW EVEN
NORTHWEST...BUT LOW LEVEL COOLING SEEMS LIKELY NORTH AND NORTHWEST
OF THE FRONT AS IT QUICKLY STRENGTHENS...AND THIS ADDS UP TO A
SIGNIFICANT FREEZING RAIN THREAT NORTH AND WEST. THIS THREAT SHOULD
CONTINUE SATURDAY AND BEGIN SHIFTING SOUTHEAST...WHILE SNOW DEVELOPS
GRADUALLY FROM THE NORTHWEST AS DYNAMIC AND EVAPORATIONAL COOLING
GAIN SWAY WITH THE APPROACH OF UPPER LOW FROM THE SOUTHWEST AND
NORTHERN STREAM UPPER TROUGH. SOME PRECIPITATION...MAINLY
SNOW...SHOULD CONTINUE INTO SUNDAY. AT THIS TIME THE FREEZING RAIN
SEEMS LIKE THE MAIN WINTER WEATHER THREAT AS THE UPPER LOW WILL
START TO BE DRIVEN MORE EAST NORTHEAST WITH TIME. THIS MEANS MOST OF
THE PRECIPITATION WILL OCCUR EARLY IN THE EVENT FROM THE GREATLY
SHARPENING THERMAL GRADIENT AND INSTABILITY. THE MORE DYNAMICALLY
RELATED PRECIPITATION LATER ON...AFTER UPPER COOLING...MAY NOT BE
TOO GREAT WITH THIS DIVERTING OF THE UPPER LOW. DESPITE DIFFERENCES
FROM YESTERDAYS RUNS...YESTERDAYS ACTION OF CUTTING OFF THE
PRECIPITATION FROM EARLY NEXT WEEK LOOKS TO BE TURNING OUT VERY
WELL. MONDAY THROUGH WEDNESDAY SHOULD BE DRY AND WITHIN SHOUTING
DISTANCE OF SEASONABLE...A BIT BELOW IT AT THE START...AS THE UPPER
RIDGING MOVES IN FROM THE WEST. THE KIND OF COLD OUTLOOK FOR THE
LONG RANGE AFTER OUR FORECAST PERIOD FROM EARLIER IN THE WEEK SEEMS
TO BE TURNING MILDER.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
QUICKLY LOOPING THROUGH THE VISIBLE SATELLITE SHOWS THAT THE
EXISTING STRATUS IS PRETTY THIN AND AT THIS TIME FAIRLY QUICKLY
ERODING FROM THE SOUTHWEST. THE RAP HAS US MIRED IN THE GUNK THROUGH
LATE TONIGHT WHILE THE OTHER MODELS TEMPORARILY BREAK US OUT OF THE
LOW END MVFR CEILINGS...THEN SUGGEST REDEVELOPMENT LATER TONIGHT. NO
EASY ANSWER HERE AS SOME QUESTION THAT IF STRATUS IS ABLE TO
DISSIPATE THIS AFTERNOON AN INCREASING SOUTHERLY GRADIENT MAY MAKE
IT DIFFICULT TO REDEVELOP. HOWEVER...WILL LEAN TOWARDS THE MORE
PESSIMISTIC SOLUTION AND PLAN ON THE STRATUS REDEVELOPING UNDER A
FAIRLY STRONG INVERSION AND THINKING MVFR TO IFR CEILINGS OVERNIGHT
MOST LOCATIONS. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
130 PM CST WED MAR 6 2013
.DISCUSSION.../ISSUED AT 445 AM CST/
LOOKS LIKE A QUIET COUPLE OF DAYS ACROSS THE REGION...BUT THAT DOES
NOT MEAN THE FORECAST IS WITHOUT ITS CHALLENGES. OF PRIMARY CONCERN
TODAY IS WIDESPREAD STRATUS WHICH IS NOW STUCK UNDER SURFACE RIDGE
ADVANCING SLOWLY EASTWARD TODAY. OTHER THAN HIGH-RESOLUTION SHORT
RANGE MODELS...WHICH SEEM TO HAVE BETTER GRASP ON CURRENT REALITY...
HAVE LITTLE USEFUL GUIDANCE TO FOLLOW REGARDING PERSISTENCE OF THE
LOW LEVEL MOISTURE. THUS FOLLOWED MORE PESSIMISTIC RAP/HRRR VIEW...
HOLDING ONTO EXTENSIVE CLOUD COVER MUCH OF THE DAY WITH POSSIBILITY
OF SOME HOLES DEVELOPING IN THE LATE AFTERNOON AS MARCH SUN HAS A
CHANCE TO ERODE AROUND ANY BREAKS WHICH MAY DEVELOP. GREATER CLOUD
COVER WILL LEAD TO COOLER TEMPS...THOUGH PREVIOUS FORECAST ALREADY
ON THE COOL SIDE WITH LIGHT FLOW ACROSS THE EAST SO DID NOT LOWER
HIGHS TOO MUCH AT THIS POINT.
FOR TONIGHT...NAM LOW LEVEL MOISTURE HINTS AT POTENTIAL FOR STRATUS
TO REDEVELOP ACROSS CENTRAL SD AS RETURN SOUTHERLY FLOW DRAWS DEEPER
MOISTURE NORTHWARD BEHIND THE DEPARTING RIDGE. IF THIS DOES DEVELOP
IT COULD LINGER INTO AT LEAST MIDDAY THURSDAY...AGAIN IMPACTING HIGH
TEMPERATURES AND COOLED HIGHS IN THE WEST BY A FEW DEGREES...THOUGH
WITH 925MB TEMPERATURES ANYWHERE FROM 4-6C...COULD STILL MIX INTO
THE MID TO UPPER 40S WEST OF THE JAMES RIVER.
ATTENTION THEN TURNS TO WEEKEND SYSTEM...WHICH MODELS HAVE COME INTO
SLIGHTLY BETTER AGREEMENT ON WHEN COMPARED TO PAST COUPLE OF NIGHTS.
FAVORED SOLUTION DEPICTS STRONGER BUT PROGRESSIVE NORTHERN STREAM
TROUGH MOVING EAST ACROSS NORTH DAKOTA/MINNESOTA SATURDAY/SATURDAY
NIGHT...WHICH DOES NOT ALLOW SOUTHERN STREAM CUTOFF LOW TO SWING
NORTH AND STRENGTHEN AS HAS BEEN SEEN IN PREVIOUS ECMWF RUNS. THIS
SOLUTION DOES GIVE THIS AREA A GOOD CHANCE OF SOME DECENT PRECIP...
WITH GOOD CONSENSUS POINTING TO LATE FRIDAY NIGHT THROUGH SATURDAY
NIGHT AS PERIODS WITH GREATEST POTENTIAL.
COULD SEE SOME LIGHT PRECIP BREAK OUT ACROSS THE WEST ALREADY BY
FRIDAY AFTERNOON...AS BROAD WARM ADVECTION BEGINS TO KICK IN. THIS
BROAD LIFT ACROSS INVERTED TROUGH REMAINS PERSISTENT INTO FRIDAY
NIGHT...WITH GROWING CONFIDENCE FOR BUMPING POPS INTO LIKELY RANGE
ACROSS MUCH OF THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL CARRY
LIKELY POPS INTO SATURDAY NIGHT OVER THE SOUTHEAST HALF OF THE CWA
AS BOUNDARY IS PULLED EAST OF THE AREA BY DEPARTING NORTHERN STREAM
WAVE.
WHILE CONFIDENCE IN PRECIPITATION CHANCE IS GROWING...PRECIPITATION
TYPE BECOMES A HUGE QUESTION MARK. GFS/ECMWF BOTH PUMP WARM AIR WELL
NORTH ACROSS THE REGION...WITH FREEZING LINE NEAR ND/SD BORDER AT
850MB...AND NEAR THE NORTHERN EDGE OF OUR FORECAST AREA AT 925MB BY
FRIDAY EVENING. CONTINUED SOUTHERLY FLOW ACROSS THE AREA FRIDAY
NIGHT KEEPS THE WARM LAYER LOCKED IN PLACE AT LEAST INTO SATURDAY
MORNING...WITH COOLING ONLY TAKING PLACE IN THE WEST BY SATURDAY
AFTERNOON/EVENING AS INVERTED TROUGH BEGINS TO ADVANCE EASTWARD.
SURFACE TEMPERATURES THEN BECOME FOCUS AND FOR NOW HAVE SUB-FREEZING
TEMPERATURES ACROSS FAR WESTERN AND NORTHERN CWA FRIDAY NIGHT INTO
SATURDAY...WITH COLD AIR COLLAPSING SOUTHWARD SATURDAY NIGHT BEHIND
DEPARTING TROUGH. FORECAST SOUNDINGS SUGGEST POTENTIAL FOR FREEZING
RAIN IN THE FAR NORTHERN/WESTERN SECTIONS GIVEN THE COLDER SURFACE
TEMPERATURES TOPPED BY WARM LAYER ABOVE 925MB. HOWEVER...STILL HAVE
ENOUGH UNCERTAINTY IN LOW LEVEL TEMPS AT THIS RANGE THAT DECIDED TO
HOLD OFF MENTIONING FREEZING RAIN FOR NOW...INSTEAD GOING WITH RAIN
OR SNOW WORDING ACROSS OUR NORTH AND WEST...GENERALLY IN THOSE AREAS
NORTHWEST OF INVERTED TROUGH. WILL ADD MENTION OF FREEZING RAIN TO
THE HWO THIS MORNING THOUGH...TO HEIGHTEN AWARENESS OF POTENTIAL FOR
ICING GIVEN TIMING OF THIS EVENT COINCIDING WITH SOUTH DAKOTA GIRLS
BASKETBALL TOURNAMENT TAKING PLACE IN VARIOUS LOCATIONS INCLUDING
HURON THIS WEEKEND.
BY SATURDAY NIGHT/SUNDAY...COOLING BEHIND THE SYSTEM SHOULD CHANGE
PRECIP OVER TO SNOW...THOUGH PRECIP SHOULD ALSO BE WANING THROUGH
THAT PERIOD SO NOT EXPECTING LARGE AMOUNTS OF SNOWFALL AT THIS TIME.
GENERALLY QUIET WEATHER RETURNS FOR EARLY NEXT WEEK. COULD SEE SOME
LIGHT PRECIP IN NORTHWEST FLOW PATTERN...BUT GIVEN SOME UNCERTAINTY
IN PATTERN AND AVAILABLE MOISTURE...WILL KEEP DRY FOR NOW WITH
TEMPERATURES REMAINING ON THE COOL SIDE OF SEASONAL NORMALS.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
QUICKLY LOOPING THROUGH THE VISIBLE SATELLITE SHOWS THAT THE
EXISTING STRATUS IS PRETTY THIN AND AT THIS TIME FAIRLY QUICKLY
ERODING FROM THE SOUTHWEST. THE RAP HAS US MIRED IN THE GUNK THROUGH
LATE TONIGHT WHILE THE OTHER MODELS TEMPORARILY BREAK US OUT OF THE
LOW END MVFR CEILINGS...THEN SUGGEST REDEVELOPMENT LATER TONIGHT. NO
EASY ANSWER HERE AS SOME QUESTION THAT IF STRATUS IS ABLE TO
DISSIPATE THIS AFTERNOON AN INCREASING SOUTHERLY GRADIENT MAY MAKE
IT DIFFICULT TO REDEVELOP. HOWEVER...WILL LEAN TOWARDS THE MORE
PESSIMISTIC SOLUTION AND PLAN ON THE STRATUS REDEVELOPING UNDER A
FAIRLY STRONG INVERSION AND THINKING MVFR TO IFR CEILINGS OVERNIGHT
MOST LOCATIONS. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
REFER TO THE MAIN FORECAST DISCUSSION SECTION FOR MORE ABOUT SKY
COVER TONIGHT.
EXPECT MVFR CLOUDS TO VERY GRADUALLY ERODE AWAY FROM WEST TO EAST
OVERNIGHT...ALTHOUGH THERE IS A LOT OF UNCERTAINTY ABOUT THE SPEED
OF THE CLEARING...IF IT OCCURS AT ALL. IF SKIES CLEAR...PATCHY FOG
WILL BE POSSIBLE. MAINLY CLEAR SKIES/VFR CONDITIONS EXPECTED
THURSDAY.
&&
.MARINE...
NORTHWEST WINDS IN THE NSH WATERS HAVE DIMINISHED BELOW
SMALL CRAFT ADVISORY CRITERIA. WILL ALLOW THE ADVY TO EXPIRE FOR THE
NORTHERN NEARSHORE MARINE ZONES...AND KEEP THE SOUTHERN ONE THROUGH
6 PM DUE TO LINGERING LARGE WAVES TOWARD THE OPEN WATERS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ645-646.
SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR LMZ643-
644.
&&
$$
TONIGHT/THURSDAY AND AVIATION/MARINE...MRC
THURSDAY NIGHT THROUGH WEDNESDAY...MEB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1213 PM CST WED MAR 6 2013
.SHORT TERM...TODAY THROUGH FRIDAY
328 AM CST WED MAR 6 2013
FORECAST CONCERNS ARE ON FOG/FREEZING FOG POTENTIAL TONIGHT INTO
THURSDAY MORNING AND TEMPERATURES THROUGH FRIDAY. FOCUS THEN QUICKLY
TURNS TO PRECIPITATION TYPE CONCERNS THIS WEEKEND AND THE POTENTIAL
FOR MODERATE TO HEAVY RAINFALL ACROSS PARTS OF THE AREA.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED LOW
PRESSURE OVER THE CENTRAL APPALACHIANS. A TROUGH WAS NOTED ALONG
THE MINNESOTA/ONTARIO BORDER. AN UPPER RIDGE WAS BUILDING ACROSS
THE WESTERN CONUS WITH A TROUGH MOVING ONTO THE WEST COAST. SURFACE
OBSERVATIONS INDICATED A RIDGE OF HIGH PRESSURE EXTENDING FROM THE
THE DAKOTAS SOUTH THROUGH THE SOUTHERN PLAINS. A SURFACE LOW WAS
NOTED OVER VIRGINIA WITH AN INVERTED TROUGH EXTENDING NORTHWEST
INTO FAR SOUTHEAST WISCONSIN.
THE TROUGH ALONG THE MINNESOTA/ONTARIO BORDER WILL PROGRESS EAST
TODAY ACROSS LAKE SUPERIOR AS THE SURFACE RIDGE EDGES EAST INTO
THE UPPER MISSISSIPPI RIVER VALLEY. THE MAIN FORECAST CHALLENGE
TODAY WILL BE CLOUD COVER. THERE ARE CURRENTLY PLENTY OF HOLES IN
THE STRATUS LAYER OVER EASTERN MINNESOTA INTO SOUTHWEST WISCONSIN.
FORECAST SOUNDINGS SHOW LOW LEVEL CLOUDS LINGERING THROUGH THE
MORNING HOURS BEFORE FINALLY CLEARING LATE THIS AFTERNOON. THE
FORECAST MODELS HAVE BEEN STRUGGLING WITH DEWPOINTS LATELY SO NOT
SOLD ON THE CLOUDS HOLDING ON AS LONG AS THE MODELS SUGGEST.
DECIDED TO GO WITH HIGHER CLOUD COVER THIS MORNING OVER THE
PREVIOUS FORECAST...WITH CLEARING OCCURRING FROM WEST TO EAST
DURING THE MID TO LATE AFTERNOON HOURS. THE NEXT CONCERN IS THE
POTENTIAL FOR FOG/FREEZING FOG TONIGHT. FOG WOULD BE MORE
FAVORABLE IF THE CLOUDS HOLD ON TODAY. SREF GUIDANCE AND FORECAST
SOUNDINGS CONTINUE TO SUGGEST FOG DEVELOPMENT TONIGHT. LOOKING
BACK TO THE WEST...UNDER THE SURFACE RIDGE...FOG HAS DEVELOPED.
THE SREF PROBABILITIES ARE CAPTURING THIS SO FEEL THEY ARE DOING A
DECENT JOB ON CAPTURING THE FOG. WILL MAINTAIN AREAS OF FOG IN THE
FORECAST OVERNIGHT INTO THURSDAY MORNING. VISIBILITIES COULD BE
REDUCED TO LESS THAN 1/2 MILE. ALSO...THE FOG COULD FREEZE TO
OBJECTS CREATING HOAR FROST. SOME LIGHT ICING MAY OCCUR ON AREA
ROADS...BUT THE RECENTLY APPLIED TREATMENT ON THE ROADS COULD
REALLY LIMIT ICING POTENTIAL. PLAN ON LOWS FALLING INTO THE SINGLE
DIGITS TONIGHT. FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH
CENTRAL WISCONSIN WILL SEE TEMPERATURES FALL INTO THE SINGLE DIGITS
BELOW ZERO.
HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY
PROVIDING QUIET WEATHER. LOOK FOR MOSTLY SUNNY SKIES ON THURSDAY
WITH HIGHS IN THE UPPER 20S TO LOWER 30S. SURFACE HIGH PRESSURE IS
EXPECTED TO SLIDE EAST OF THE AREA ON FRIDAY AS A POTENT TROUGH
DIVES INTO THE SOUTHWEST CONUS. MEANWHILE LOW PRESSURE DEVELOPS
OVER EASTERN COLORADO AS A WARM FRONT LIFTS NORTH OUT OF THE
CENTRAL PLAINS. TWO MAIN FEATURES TO WATCH CLOSELY ON FRIDAY...A
NORTHERN STREAM TROUGH DIVING SOUTH OUT OF CENTRAL SASKATCHEWAN
AND THE SOUTHWEST LOW LIFTING NORTHEAST TOWARD THE REGION. THE
WARM FRONT LOOKS TO LIFT NORTH INTO SOUTHERN MINNESOTA/SOUTHERN
WISCONSIN FRIDAY NIGHT INTO SATURDAY MORNING THEN LIFTING NORTH
THROUGH THE DAY ON SATURDAY. THE NORTHERN STREAM WAVE AND ENERGY
EJECTING OUT OF THE SOUTHWEST WILL INTERACT WITH THE FRONT
BRINGING PRECIPITATION TO THE AREA. WARM AIR ALOFT WILL SURGE INTO
THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT LEADING TO A MIX
OF PRECIPITATION TYPES. A MIX OF FREEZING RAIN...SLEET AND SNOW IS
EXPECTED FRIDAY EVENING INTO EARLY SATURDAY MORNING SWITCHING OVER
TO MAINLY RAIN DURING THE DAY ON SATURDAY. SOME ICE ACCUMULATION
IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A MOISTURE RICH
AIRMASS MOVES INTO THE AREA DURING THE DAY ON SATURDAY WITH
PRECIPITABLE WATER VALUES APPROACHING 270 PERCENT OF NORMAL.
ALSO...TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO
LOWER 40S. 925/850 MB MOISTURE TRANSPORT FOCUSES INTO SOUTHERN
WISCONSIN AND FAR NORTHEAST IOWA SATURDAY INTO SATURDAY NIGHT.
PERIODS OF MODERATE TO HEAVY RAINFALL LOOK POSSIBLE SATURDAY INTO
SATURDAY NIGHT LEADING TO LOCALIZED FLOODING AND ICE JAMS ON AREA
RIVERS. FORECAST MODELS ARE JUST STARTING TO COME INTO AGREEMENT
ON THIS WARMER AND WET SOLUTION SO WILL HAVE TO KEEP A CLOSE WATCH
ON THE NEXT FEW RUNS.
.LONG TERM...SATURDAY THROUGH TUESDAY
328 AM CST WED MAR 6 2013
06.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY INTO
SATURDAY NIGHT BUT THEN START TO DIVERGE SUNDAY INTO EARLY MONDAY.
THE ECMWF SHIFTS THE BOUNDARY SOUTHEAST AND EAST OF THE AREA AS AN
UPPER LOW WRAPS UP OVER THE OHIO RIVER VALLEY. THE GFS LEANS TOWARD
THIS SOLUTION BUT IT IS FASTER THAN THE ECMWF...TAKING THE LOW
NORTH INTO THE EASTERN GREAT LAKES EARLY ON MONDAY. THE GEM OFFERS
A DIFFERENT SOLUTION WITH THE LOW TAKING SHAPE OVER NORTHERN
ILLINOIS WHICH WOULD BRING SIGNIFICANT SNOWFALL TO NORTHERN
WISCONSIN THROUGH SOUTHERN/CENTRAL MINNESOTA. HAVE LEANED TOWARD A
MODEL CONSENSUS BLEND APPROACH MONDAY INTO TUESDAY WITH CHANCES
FOR SNOW MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE AREA. SNOW
CHANCES WILL CONTINUE ACROSS NORTH CENTRAL WISCONSIN ON TUESDAY AS
SHORTWAVE MOVES ACROSS NORTHERN WISCONSIN. PLAN ON TEMPERATURES
COOLING SLIGHTLY EARLY NEXT WEEK WITH HIGHS FALLING INTO THE 30S
AND LOWS IN THE TEENS TO LOWER 20S.
&&
.AVIATION...THROUGH 18Z THURSDAY
1212 PM CST WED MAR 6 2013
FORECAST IS OF LOWER CONFIDENCE...ESPECIALLY FURTHER WEST AT KRST.
SATELLITE IMAGERY INDICATING A VERY EXPANSIVE MVFR CLOUD DECK
ACROSS THE REGION WITH SOME OLES OPENING UP INTO MVFR SCT/BKN
CONDITIONS /THUS THE TEMPO IN THE TAFS/. THE CLOUD LAYER IS VERY THIN
PER SATELLITE IMAGERY AS RIVERS ARE VISIBLE THROUGH IT. ANOTHER
SOMEWHAT DRYING PUSH OF AIR IS COMING IN FROM THE NORTH ASSOCIATED
WITH A WEATHER SYSTEM TRAVELING ACROSS CANADA. THIS LOOKS TO
POSSIBLY PROVIDE AN INFLUENCE OF CLOUD DIMINISHMENT BY EVENING AND
AFTER FROM THE NORTH.
HOWEVER...THE LOW LEVEL MOISTURE IS SITUATED WITHIN THE SURFACE
RIDGE WITH LIGHT WIND FLOW OVER MN/DAKOTAS. THIS SURFACE RIDGING
WILL SHIFT EAST AND BE LOCATED OVER THE MISS RIVER /KLSE/ BY
MORNING. THIS MORNING...WEST OF THE RIDGE AXIS...LIFR CONDITIONS
OCCURRED AND FG/CIGS IN THE LIFR RANGE. EXTRAPOLATING THIS TO THU
MORNING...THIS LIFR SYNOPTIC AREA WOULD BE OVER MN WITH KRST ON THE
EASTERN EDGE. SHORT RANGE MODEL ENSEMBLES /SREF/ INDICATE A HIGHER
PROBABILITY OF IFR ALONG AND WEST OF I-35...BUT VERY CLOSE TO
KRST.
THIS AFTERNOON...MARCH SUN ANGLES WILL WORK ON THINNING THE CLOUDS
AND EXPANDING THE PATCHES OF SCT/BKN OPENING UP. PREVIOUS FORECAST
HAD SCT CLOUDS BY LATE AFTERNOON...AND THEN MVFR BR FORMING.
ALTHOUGH CLOUDS ARE STILL WIDESPREAD AT 18Z...HAVE STAYED THE COURSE
ON CLEARING BY LATE AFTERNOON. BUT CONFIDENCE IS VERY LOW AND MVFR
CIGS COULD VERY WELL BE IN PLACE OVERNIGHT. IF THIS OCCURS...WOULD
THINK KRST COULD LOWER TO IFR CIGS BY MORNING. KLSE SHOULD REMAIN
MVFR. OVERALL...THIS FORECAST IS THE MOST OPTIMISTIC VERSION AT
THIS TIME AND FORECAST CHANGES WOULD PROBABLY BE TOWARD WORSENING
THE CIG/VSBYS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
328 AM CST WED MAR 6 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...BAUMGARDT