Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/13/13
AREA FORECAST DISCUSSION
NWS TAUNTON MA
422 PM EDT SAT MAY 11 2013
.SYNOPSIS...
SHOWERS AND OCCASIONAL THUNDERSTORMS CONTINUE THIS EVENING AND
OVERNIGHT AS A COLD FRONT SLOWLY CROSSES THE REGION. THE FRONT
WILL THEN STALL SUNDAY BEFORE MOVING TO THE EAST SUNDAY NIGHT.
COOLER AND DRIER WEATHER WILL FOLLOW FOR EARLY NEXT WEEK. EXPECT A
RETURN TO A MORE UNSETTLED PATTERN FOR THE LATTER PART OF NEXT
WEEK AS A FRONT STALLS OVER OR JUST SOUTH OF THE AREA.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
* SOME THUNDER THIS EVENING AND OVERNIGHT.
* PRIMARY THREATS...GUSTY WINDS AND OCCASIONAL URBAN/POOR DRAINAGE
FLOODING
INITIAL CONVECTIVE BAND CONTINUES TO WEAKEN ALONG THE S COASTAL
WATERS AND WILL CLIP SE MA AND SRN RI THROUGH THE EARLY EVENING.
MOST OF THE THUNDER ASSOCIATED WITH THIS BAND SHOULD REMAIN WELL S
OF LAND PRIMARILY DUE TO MOSTLY CLEAR SKIES WHICH HAVE STAYED
FURTHER S ALL DAY. CONDITIONS ARE GENERALLY MORE STABLE TO THE N.
HOWEVER...WILL NEED TO CONTINUE TO MONITOR DEVELOPING CONVECTION
MORE CLOSELY ASSOCIATED WITH A COLD FRONTAL BOUNDARY CURRENTLY
LOCATED THROUGH CENTRAL NY AND INTO PA. COMBINATION OF SLIGHTLY
HIGHER DWPTS AND SOME CLEARING OF THE MID AND HIGH LVL CLOUDS HAS
ALLOWED CONVECTION TO FIRE AND BECOME A BIT MORE ORGANIZED IN SRN
NY AND NJ. WILL NEED TO MONITOR THIS AS THE FRONT MAKES ITS E
PROGRESSION. MESOSCALE MODELS CONTINUE TO INDICATE SOME
DESTABILIZATION OVER SRN NEW ENGLAND...BUT NOT NEARLY AS MUCH AS
WHERE CLEARING HAS OCCURRED. THEREFORE...WILL HAVE TO WATCH THE
CLEARING THROUGH THE EVENING WHILE THE SUN IS STILL UP. SB CAPE
VALUES HAVE SHOT UP TO ABOUT 1000 J/KG IN THE AREAS WHERE CLEARING
HAS OCCURRED. SHEAR STILL DECENT...WITH 30-40 KT 0-6KM OUT OF THE
W...HOWEVER IT WOULD NEED THE BETTER DESTABILIZATION FOR ANY
STORMS TO BECOME ORGANIZED.
OVERNIGHT HOWEVER...THE TREND WILL BE TOWARD SOME UPPER LVL
INSTABILITY AS NOSE OF 40 KT LLJ MOVES OVER ESPECIALLY S AND SE
AREAS. STILL NOTING 1.0+ INCH PWAT AIRMASS AND DECENT THETA-E
RIDGING TO WORK WITH PARTICULARLY RI AND E MASS AFTER THE BAND OF
INTERIOR CONVECTION WEAKENS WITH TIME OVER THE AREA.
THEREFORE...THE TRANSITION...AND PRIMARY THREAT WILL BE TOWARD THE
POTENTIAL FOR ISOLATED HEAVY DOWNPOURS WITH A FOCUS ON THE E AS
THE FRONT BEGINS TO CROSS THE AREA AND STALL. THUNDER STILL NOT
OUR OF THE QUESTION...BUT ITS LIKELY TO BE MORE ISOLATED IN NATURE
THAN THIS AFTERNOON AND EARLY EVENING. TYPICAL POOR DRAINAGE
FLOODING IS POSSIBLE IN SOME SPOTS...PARTICULARLY WITH ANY
CONVECTIVE ELEMENTS THAT FORM THIS EVENING OR OVERNIGHT. HRRR POPS
HAVE BEEN QUITE GOOD TODAY...SO ADJUSTED THE EVENING AND OVERNIGHT
POPS TOWARD ITS SOLUTION.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SUNDAY...
SFC COLD FRONT PROGGED TO STALL IN ERN MA DURING THE EARLY MORNING
HOURS UNTIL SECONDARY KICKER WAVE ROTATES W TO E AROUND THE CUTOFF
LOW PRES IN QUEBEC. AT THE SAME TIME...MODELS CONTINUE TO INDICATE
A SECONDARY SURGE OF HIGHER THETA-E ARE AND A SECONDARY LLJ TO
MOVE UP AND E OF THE THIS FRONT DURING THE MORNING HOURS. GIVEN
THIS...EVEN AS BULK OF PRECIP SLOWLY SHIFTS OFFSHORE OF ERN MA AND
THE CAPE/ISLANDS...MAY SEE ANOTHER HEAVIER BAND OF PRECIPITATION
FORM DURING THE DAYLIGHT HOURS AND CROSS FROM S TO N PARTICULARLY
OVER E AND SE PORTIONS OF THE FORECAST AREA. ALSO...WITH SOME
BREAKS POSSIBLE...AND THE CONVERGENCE PROVIDED BY THE FRONT...MAY
SEE -SHRA AND EVEN AN ISOLATED RUMBLE OF THUNDER AS FAR WEST AS A
IJD-ORH-MHT LINE. HOWEVER...WITH THE COMBINATION OF THIS KICKER
WAVE ALLOWING THE FRONT TO PROGRESS...AND A DRIER MORE STABLE
AIRMASS FILTERING IN BEHIND THE FRONT...NOT EXPECTING RAINFALL TO
BE AS WIDESPREAD OR AS POTENTIALLY HEAVY EVERYWHERE AS IT WAS ON
SATURDAY. MOST LOCATIONS W OF THE LINE ABOVE REMAIN DRY AND
PROGRESSIVELY GIVE WAY TO SUNNY SKIES. THIS TOO WILL BE THE TREND
FOR THE EAST BY LATE AFTERNOON AND EVENING MODELS INDICATE. WILL
NEED TO WATCH SE MASS...CAPE/ISLANDS ESPECIALLY FOR ANY HEAVY
RAINFALL. MAY NEED TO MONITOR THE CAPE/ISLANDS FOR A SECONDARY
DENSE FOG THREAT SHOULD THE PRECIP MOVE A LITTLE BIT FURTHER
OFFSHORE...BUT WITH RAIN MIXING IN THE BL...IT APPEARS TO BE A
SLIGHTLY LOWER THREAT THAN PREVIOUS NIGHTS.
SUN NIGHT...
CLEARING TREND EXPECTED DURING THE OVERNIGHT HOURS. HOWEVER...SFC
PRES GRADIENT IS EXPECTED TO REMAIN AT LEAST SOMEWHAT TIGHT...SO
NOT EXPECTING FULL DECOUPLING. EVEN STILL TEMPERATURES ARE
EXPECTED TO DIP TO NEAR FREEZING IN NW MA AND PORTIONS OF SW NH
WITH MID TO UPPER 30S TOWARD THE S AND E. WINDS AROUND 10 MPH
WOULD PRECLUDE FROST POTENTIAL...BUT THIS WILL NEED TO BE
MONITORED GIVEN NEWLY ACTIVATED GROWING SEASON IN SOME SPOTS AND
TEMPERATURES DIPPING CLOSE TO THE FREEZING MARK.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
HIGHLIGHTS...
* COOL AND DRY MONDAY AND TUESDAY
* UNSETTLED WEATHER THE LATTER HALF OF THE WEEK
THERE IS REASONABLY GOOD AGREEMENT ON THE LARGE SCALE PATTERN BY
THE MEDIUM RANGE MODELS THROUGH THE COMING WEEK. RELATIVELY HIGH
AMPLITUDE TROF BRINGS UNSEASONABLY CHILLY AIR MASS TO THE REGION
MON THRU TUE NIGHT. RIDGE ACROSS THE S CENTRAL US BUILDS EAST ON
WED BUT STRONG TROF ACROSS CANADA SHOULD KEEP RELATIVELY FAST WEST
TO EAST FLOW ACROSS SOUTHERN NEW ENGLAND WITH A HIGH LIKELIHOOD OF
A FRONT STALLING OVER OR JUST SOUTH OF THE FORECAST AREA. BY THE
WEEKEND...LOOKS LIKE A DRY NW FLOW BECOMES ESTABLISHED OVER THE
AREA WITH DRY AND PROBABLY SEASONABLE TEMPERATURES.
MON THRU TUE NIGHT...SHOULD BE DRY AND COOL WITH -1 TO -3C 850MB
TEMP AIR. THE AVERAGE START OF THE GROWING SEASON EXPANDED INTO A
LARGE PART...BUT NOT ALL...OF INTERIOR SOUTHERN NEW ENGLAND ON MAY
10. THERE MAY BE A NEED FOR FROST ADVISORIES OR FREEZE WARNINGS
FOR A PORTION OF THE AREA MON NIGHT UNDER CLEAR SKIES AND PROBABLY
DECOUPLING WINDS OVER THE INTERIOR TO ASSIST WITH RADIATIONAL
COOLING...ALBEIT FOR A RELATIVELY SHORT NIGHT AT THIS TIME OF
YEAR.
WED INTO WED NIGHT...SPELL A CHANGE IN THE WEATHER PATTERN.
ALTHOUGH THERE ARE SOME TIMING DIFFERENCES...MEDIUM RANGE MODELS
SUGGEST WARM ADVECTION BECOMING ESTABLISHED ON WED...AND BY WED
EVENING THE WARM ADVECTION MAY TRIGGER ENOUGH OF AN INSTABILITY
BURST AS SEEN IN K INDEX PROJECTIONS FOR AT LEAST SCT SHOWERS AND
TSTMS.
THU THRU FRI...WILL PROBABLY BE UNSETTLED AS FRONTAL BOUNDARY
STALLS OVER OR A LITTLE SOUTH OF SOUTHERN NEW ENGLAND AND REGION
IS VULNERABLE SHORT WAVE ENERGY PASSING BETWEEN A SOUTHERN UPPER
RIDGE AND E CENTRAL CANADA TROF. IT IS TOO FAR OUT IN TIME TO HAVE
MUCH CONFIDENCE IN DETAILS BUT FOR NOW INDICATED CONSIDERABLE
CLOUDINESS AND CHANCE SHOWERS/TSTMS.
SAT...BOTH 12Z ECMWF AND GFS SUGGEST A DRIER NW FLOW BECOMING
ESTABLISHED ALTHOUGH CONFIDENCE THAT FAR OUT IS NOT TOO HIGH. BY
THE WEEKEND...DIFFERENCES IN THE SYNOPTIC FLOW BECOME MORE
APPARENT WITH THE ECMWF DEPICTING A STRONGER NORTHERN STREAM AND
THE GFS SHOWING A WEAKER NORTHERN STREAM.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...LOW CONFIDENCE...PARTICULARLY ON TIMING OF ANY LOW
CIGS/VSBYS INTO SUN MORNING.
THROUGH MID MORNING SUN...
AS A SLOW MOVING COLD FRONT CROSSES THE AREA...EXPECTING A COMPLEX
MIX OF VFR/MVFR/IFR THIS AFTERNOON IN OCCASIONAL -SHRA AND LOW
CIGS. A THUNDERSTORM OR TWO CAN/T BE RULED OUT LATE THIS AFTERNOON
OR EVENING AS WELL. OTHERWISE...THE TREND WILL BE TOWARD ALL IFR
AS FOG AND LOW CIGS DEVELOP THIS EVENING AND LINGER MUCH OF THE
NIGHT. SHOWERS CONTINUE ACROSS THE REGION DURING THIS TIME AS
WELL. EXPECT IMPROVEMENT FROM W TO E DURING THE EARLY TO MID
MORNING HOURS...BUT WILL LIKELY SEE MOSTLY IFR IN THE EAST.
EARLY AFTERNOON SUN THROUGH SUN NIGHT...
IMPROVING CONDITIONS WITH LIKELY VFR EVERYWHERE BY AFTERNOON SUN.
THE VFR CONDITIONS CONTINUE INTO SUN NIGHT. WINDS MAY GUST TO 20
KT DURING THE DAY SUN OUT OF THE W.
KBOS TERMINAL...OVERALL LOW CONFIDENCE ON CIG FORECAST. WE HAVE
MAINLY VFR CIGS TODAY...LOWERING TO IFR TONIGHT. BUT LOWER CIGS
COULD DEVELOP EARLIER.
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.
OUTLOOK...MONDAY THROUGH THURSDAY...
HIGH CONFIDENCE OF VFR CONDITIONS MON THROUGH MUCH OF WED.
MODERATE CONFIDENCE OF DEVELOPING MVFR CONDITIONS IN SHOWERS AND
PATCHY FOG WED EVE AND OCCASIONAL MVFR CONDITIONS IN SCT
SHOWERS/TSTMS AND PATCHY FOG WED NIGHT THRU THU.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
FORECAST CONFIDENCE HIGH THROUGH SUNDAY NIGHT.
OVERNIGHT...WINDS OF 25-30 KT GRADUALLY SUBSIDE THIS
EVENING...EXCEPT FOR THE POTENTIAL FOR HIGHER GUSTS IN ANY
THUNDERSTORMS WHICH MAY CROSS THE WATERS /PARTICULARLY SRN
WATERS/ OVERNIGHT. HOWEVER...SEAS WITH BUILDING SWELL ARE LIKELY
TO STAY ELEVATED 5-7 FT OVER SRN WATERS AND E OUTER WATERS. SMALL
CRAFT ADVISORIES CONTINUE.
SUNDAY...
SMALL CRAFT ADVISORIES CONTINUE FOR SEAS ON THE OUTER WATERS SRN
WATERS IMMEDIATELY S OF RHODE ISLAND. HOWEVER...MAY SEE A SECOND
SURGE OF WIND GUSTS...PARTICULARLY NEAR SHORE...TO 25 KT. SO MAY
NEED TO RE-ISSUE SMALL CRAFT ADVISORY FOR THE DAYLIGHT HOURS ON
SOME NEAR SHORE ZONES.
SUN NIGHT...
ASIDE FROM CONTINUING SWELL ON OUTER WATERS /WHERE SCA CONTINUES/
SEAS AND WINDS SUBSIDE.
OUTLOOK...MONDAY THROUGH THURSDAY...
ENOUGH NW TO N GRADIENT MAY RESULT IN SCA GUSTS OVER THE COASTAL
WATERS MON INTO MON EVE. LIGHT WINDS AND SUBSIDING SEAS EXPECTED
TUE. ALTHOUGH WINDS WILL BE INCREASING ALOFT...SURFACE WINDS ARE
PRESENTLY EXPECTED TO REMAIN LIGHT WED INTO THU...EXCEPT IN
VICINITY OF ANY ISOLD TSTMS WED NIGHT AND THU.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ230>234-236-251.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT SUNDAY FOR ANZ235-237-250.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DOODY/THOMPSON
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...THOMPSON
AVIATION...DOODY/THOMPSON
MARINE...DOODY/THOMPSON
AREA FORECAST DISCUSSION
NWS TAUNTON MA
401 PM EDT SAT MAY 11 2013
.SYNOPSIS...
SHOWERS AND OCCASIONAL THUNDERSTORMS CONTINUE THIS EVENING AND
OVERNIGHT AS A COLD FRONT SLOWLY CROSSES THE REGION. THE FRONT
WILL THEN STALL SUNDAY BEFORE MOVING TO THE EAST SUNDAY NIGHT.
COOLER AND DRIER WEATHER WILL FOLLOW FOR EARLY NEXT WEEK. EXPECT A
RETURN TO A MORE UNSETTLED PATTERN FOR THE LATTER PART OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
* SOME THUNDER THIS EVENING AND OVERNIGHT.
* PRIMARY THREATS...GUSTY WINDS AND OCCASIONAL URBAN/POOR DRAINAGE
FLOODING
INITIAL CONVECTIVE BAND CONTINUES TO WEAKEN ALONG THE S COASTAL
WATERS AND WILL CLIP SE MA AND SRN RI THROUGH THE EARLY EVENING.
MOST OF THE THUNDER ASSOCIATED WITH THIS BAND SHOULD REMAIN WELL S
OF LAND PRIMARILY DUE TO MOSTLY CLEAR SKIES WHICH HAVE STAYED
FURTHER S ALL DAY. CONDITIONS ARE GENERALLY MORE STABLE TO THE N.
HOWEVER...WILL NEED TO CONTINUE TO MONITOR DEVELOPING CONVECTION
MORE CLOSELY ASSOCIATED WITH A COLD FRONTAL BOUNDARY CURRENTLY
LOCATED THROUGH CENTRAL NY AND INTO PA. COMBINATION OF SLIGHTLY
HIGHER DWPTS AND SOME CLEARING OF THE MID AND HIGH LVL CLOUDS HAS
ALLOWED CONVECTION TO FIRE AND BECOME A BIT MORE ORGANIZED IN SRN
NY AND NJ. WILL NEED TO MONITOR THIS AS THE FRONT MAKES ITS E
PROGRESSION. MESOSCALE MODELS CONTINUE TO INDICATE SOME
DESTABILIZATION OVER SRN NEW ENGLAND...BUT NOT NEARLY AS MUCH AS
WHERE CLEARING HAS OCCURRED. THEREFORE...WILL HAVE TO WATCH THE
CLEARING THROUGH THE EVENING WHILE THE SUN IS STILL UP. SB CAPE
VALUES HAVE SHOT UP TO ABOUT 1000 J/KG IN THE AREAS WHERE CLEARING
HAS OCCURRED. SHEAR STILL DECENT...WITH 30-40 KT 0-6KM OUT OF THE
W...HOWEVER IT WOULD NEED THE BETTER DESTABILIZATION FOR ANY
STORMS TO BECOME ORGANIZED.
OVERNIGHT HOWEVER...THE TREND WILL BE TOWARD SOME UPPER LVL
INSTABILITY AS NOSE OF 40 KT LLJ MOVES OVER ESPECIALLY S AND SE
AREAS. STILL NOTING 1.0+ INCH PWAT AIRMASS AND DECENT THETA-E
RIDGING TO WORK WITH PARTICULARLY RI AND E MASS AFTER THE BAND OF
INTERIOR CONVECTION WEAKENS WITH TIME OVER THE AREA.
THEREFORE...THE TRANSITION...AND PRIMARY THREAT WILL BE TOWARD THE
POTENTIAL FOR ISOLATED HEAVY DOWNPOURS WITH A FOCUS ON THE E AS
THE FRONT BEGINS TO CROSS THE AREA AND STALL. THUNDER STILL NOT
OUR OF THE QUESTION...BUT ITS LIKELY TO BE MORE ISOLATED IN NATURE
THAN THIS AFTERNOON AND EARLY EVENING. TYPICAL POOR DRAINAGE
FLOODING IS POSSIBLE IN SOME SPOTS...PARTICULARLY WITH ANY
CONVECTIVE ELEMENTS THAT FORM THIS EVENING OR OVERNIGHT. HRRR POPS
HAVE BEEN QUITE GOOD TODAY...SO ADJUSTED THE EVENING AND OVERNIGHT
POPS TOWARD ITS SOLUTION.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SUNDAY...
SFC COLD FRONT PROGGED TO STALL IN ERN MA DURING THE EARLY MORNING
HOURS UNTIL SECONDARY KICKER WAVE ROTATES W TO E AROUND THE CUTOFF
LOW PRES IN QUEBEC. AT THE SAME TIME...MODELS CONTINUE TO INDICATE
A SECONDARY SURGE OF HIGHER THETA-E ARE AND A SECONDARY LLJ TO
MOVE UP AND E OF THE THIS FRONT DURING THE MORNING HOURS. GIVEN
THIS...EVEN AS BULK OF PRECIP SLOWLY SHIFTS OFFSHORE OF ERN MA AND
THE CAPE/ISLANDS...MAY SEE ANOTHER HEAVIER BAND OF PRECIPITATION
FORM DURING THE DAYLIGHT HOURS AND CROSS FROM S TO N PARTICULARLY
OVER E AND SE PORTIONS OF THE FORECAST AREA. ALSO...WITH SOME
BREAKS POSSIBLE...AND THE CONVERGENCE PROVIDED BY THE FRONT...MAY
SEE -SHRA AND EVEN AN ISOLATED RUMBLE OF THUNDER AS FAR WEST AS A
IJD-ORH-MHT LINE. HOWEVER...WITH THE COMBINATION OF THIS KICKER
WAVE ALLOWING THE FRONT TO PROGRESS...AND A DRIER MORE STABLE
AIRMASS FILTERING IN BEHIND THE FRONT...NOT EXPECTING RAINFALL TO
BE AS WIDESPREAD OR AS POTENTIALLY HEAVY EVERYWHERE AS IT WAS ON
SATURDAY. MOST LOCATIONS W OF THE LINE ABOVE REMAIN DRY AND
PROGRESSIVELY GIVE WAY TO SUNNY SKIES. THIS TOO WILL BE THE TREND
FOR THE EAST BY LATE AFTERNOON AND EVENING MODELS INDICATE. WILL
NEED TO WATCH SE MASS...CAPE/ISLANDS ESPECIALLY FOR ANY HEAVY
RAINFALL. MAY NEED TO MONITOR THE CAPE/ISLANDS FOR A SECONDARY
DENSE FOG THREAT SHOULD THE PRECIP MOVE A LITTLE BIT FURTHER
OFFSHORE...BUT WITH RAIN MIXING IN THE BL...IT APPEARS TO BE A
SLIGHTLY LOWER THREAT THAN PREVIOUS NIGHTS.
SUN NIGHT...
CLEARING TREND EXPECTED DURING THE OVERNIGHT HOURS. HOWEVER...SFC
PRES GRADIENT IS EXPECTED TO REMAIN AT LEAST SOMEWHAT TIGHT...SO
NOT EXPECTING FULL DECOUPLING. EVEN STILL TEMPERATURES ARE
EXPECTED TO DIP TO NEAR FREEZING IN NW MA AND PORTIONS OF SW NH
WITH MID TO UPPER 30S TOWARD THE S AND E. WINDS AROUND 10 MPH
WOULD PRECLUDE FROST POTENTIAL...BUT THIS WILL NEED TO BE
MONITORED GIVEN NEWLY ACTIVATED GROWING SEASON IN SOME SPOTS AND
TEMPERATURES DIPPING CLOSE TO THE FREEZING MARK.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
HIGHLIGHTS...
* COOLER AND DRIER WEATHER MONDAY AND TUESDAY
* MORE UNSETTLED WEATHER RETURNS MIDDLE OF NEXT WEEK
THE MODELS EXHIBIT GOOD AGREEMENT ON SYNOPTIC SCALE FEATURES
THROUGHOUT MUCH OF THE FORECAST PERIOD. HIGH PRESSURE BUILDS INTO
SOUTHERN NEW ENGLAND MONDAY AND TUESDAY AS LOW PRESSURE MOVES UP
THE COAST...PASSING EAST OF SOUTHERN NEW ENGLAND TUESDAY. SHOWERS
ARE POSSIBLE WEDNESDAY AHEAD OF A COLD FRONT THAT WILL MOVE
THROUGH THE AREA THURSDAY. THERE ARE SOME DIFFERENCES BETWEEN THE
GFS AND ECMWF TOWARDS THE END OF NEXT WEEK. THE EURO IS SLOWER
MOVING AN EAST COAST RIDGE OUT TO SEA WHILE THE GFS MOVES IT OUT
FAIRLY QUICKLY ALLOWING ANOTHER LOW PRESSURE SYSTEM TO AFFECT THE
AREA FRIDAY. GENERALLY WENT WITH A BLEND OF GUIDANCE FOR THE
FORECAST.
SUNDAY NIGHT THROUGH WEDNESDAY...HIGH PRESSURE STARTS TO BUILD
INTO THE EAST MONDAY AND TUESDAY AS LOW PRESSURE MOVES UP THE
COAST WELL EAST OF THE AREA INTO THE MARITIMES. THE HIGH PRESSURE
WILL MOVE OFFSHORE WEDNESDAY. MUCH OF THIS PERIOD IS EXPECTED TO
BE DRY... THOUGH A COLD CORE ALOFT WILL STEEPEN LAPSE RATES ENOUGH
THAT TOGETHER WITH DAYTIME HEATING COULD PRODUCE SOME DIURNAL
SHOWERS. BELOW AVERAGE TEMPERATURES ARE EXPECTED WITH MOSTLY SUNNY
SKIES. THE BIG IMPACT HERE WILL BE OVERNIGHT...WITH TEMPERATURES
EXPECTED TO DROP INTO THE 30S. WILL KEEP THE FROST WORDING IN THE
WEATHER GRIDS. MONDAY NIGHT LOOKS TO BE THE CHILLIEST NIGHT WITH
TEMPERATURES POSSIBLY DOWN TO FREEZING ACROSS PORTIONS OF THE
NORTHWESTERN ZONES.
THURSDAY AND FRIDAY...PLENTY OF UNCERTAINTY HERE WITH DIFFERENT
SYNOPTIC PATTERNS IN THE MODELS. THE ECMWF KEEPS THE UPPER LEVEL
RIDGE OVER THE EAST COAST A BIT LONGER THAN THE GFS. REGARDLESS...
THIS PERIOD LOOKS TO BE A BIT MORE UNSETTLED THAN EARLIER IN THE
WEEK. IT DOES LOOK AS THOUGH TEMPERATURES WILL RETURN TO NORMAL
OR POSSIBLY ABOVE NORMAL LEVELS THROUGH THE END OF THE WEEK.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...LOW CONFIDENCE...PARTICULARLY ON TIMING OF ANY LOW
CIGS/VSBYS INTO SUN MORNING.
THROUGH MID MORNING SUN...
AS A SLOW MOVING COLD FRONT CROSSES THE AREA...EXPECTING A COMPLEX
MIX OF VFR/MVFR/IFR THIS AFTERNOON IN OCCASIONAL -SHRA AND LOW
CIGS. A THUNDERSTORM OR TWO CAN/T BE RULED OUT LATE THIS AFTERNOON
OR EVENING AS WELL. OTHERWISE...THE TREND WILL BE TOWARD ALL IFR
AS FOG AND LOW CIGS DEVELOP THIS EVENING AND LINGER MUCH OF THE
NIGHT. SHOWERS CONTINUE ACROSS THE REGION DURING THIS TIME AS
WELL. EXPECT IMPROVEMENT FROM W TO E DURING THE EARLY TO MID
MORNING HOURS...BUT WILL LIKELY SEE MOSTLY IFR IN THE EAST.
EARLY AFTERNOON SUN THROUGH SUN NIGHT...
IMPROVING CONDITIONS WITH LIKELY VFR EVERYWHERE BY AFTERNOON SUN.
THE VFR CONDITIONS CONTINUE INTO SUN NIGHT. WINDS MAY GUST TO 20
KT DURING THE DAY SUN OUT OF THE W.
KBOS TERMINAL...OVERALL LOW CONFIDENCE ON CIG FORECAST. WE HAVE
MAINLY VFR CIGS TODAY...LOWERING TO IFR TONIGHT. BUT LOWER CIGS
COULD DEVELOP EARLIER.
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR.
COULD SEE MVFR/IFR CONDITIONS IN DIURNAL SHOWERS EACH DAY.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
FORECAST CONFIDENCE HIGH THROUGH SUNDAY NIGHT.
OVERNIGHT...WINDS OF 25-30 KT GRADUALLY SUBSIDE THIS
EVENING...EXCEPT FOR THE POTENTIAL FOR HIGHER GUSTS IN ANY
THUNDERSTORMS WHICH MAY CROSS THE WATERS /PARTICULARLY SRN
WATERS/ OVERNIGHT. HOWEVER...SEAS WITH BUILDING SWELL ARE LIKELY
TO STAY ELEVATED 5-7 FT OVER SRN WATERS AND E OUTER WATERS. SMALL
CRAFT ADVISORIES CONTINUE.
SUNDAY...
SMALL CRAFT ADVISORIES CONTINUE FOR SEAS ON THE OUTER WATERS SRN
WATERS IMMEDIATELY S OF RHODE ISLAND. HOWEVER...MAY SEE A SECOND
SURGE OF WIND GUSTS...PARTICULARLY NEAR SHORE...TO 25 KT. SO MAY
NEED TO RE-ISSUE SMALL CRAFT ADVISORY FOR THE DAYLIGHT HOURS ON
SOME NEAR SHORE ZONES.
SUN NIGHT...
ASIDE FROM CONTINUING SWELL ON OUTER WATERS /WHERE SCA CONTINUES/
SEAS AND WINDS SUBSIDE.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
EXPECT SEAS OF 5 TO 7 FEET ON THE OUTER WATERS SUNDAY NIGHT. SEAS
WILL DIMINISH MONDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS
OVER THE WATERS. SCA SEAS WILL CONTINUE ON THE OUTER WATERS
THROUGH MONDAY AFTERNOON. WESTERLY WINDS WILL FLIRT WITH SCA
CRITERIA SUNDAY NIGHT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ230>234-236-251.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT SUNDAY FOR ANZ235-237-250.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DOODY/THOMPSON
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...THOMPSON
AVIATION...DOODY/THOMPSON
MARINE...DOODY/THOMPSON
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1011 AM EDT SAT MAY 11 2013
.SYNOPSIS...
SHOWERS AND SCATTERED THUNDERSTORMS AHEAD OF A COLD FRONT ARE
EXPECTED INTO TONIGHT. THE COLD FRONT WILL MOVE ACROSS THE REGION
LATE TONIGHT AND STALL SUNDAY BEFORE MOVING TO THE EAST SUNDAY
NIGHT. COOLER AND DRIER WEATHER WILL FOLLOW FOR EARLY NEXT WEEK.
EXPECT A RETURN TO A MORE UNSETTLED PATTERN FOR THE LATTER PART
OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10 AM UPDATE...
A LITTLE BIT OF LOW TO MID LVL RIDGING EVIDENT AHEAD CONVECTIVE
COMPLEX OVER NJ/DE AND ERN PA. THIS HAS LEAD TO A LITTLE BIT OF A
BREAK IN THE -SHRA ACTIVITY ACROSS THE REGION THIS MORNING.
HOWEVER...AM NOTING SOME BREAKS IN THE SKIES IN VIS SATELLITE
IMAGES AND LOCAL WEB CAMS CONFIRM SUNSHINE BEGINNING TO SHOW
THROUGH. MESOSCALE MODELS STILL SUPPORT MOST OF THE INSTABILITY
IS WELL S OF THE REGION...AND DUE E OF THE CONVECTIVE COMPLEX.
HOWEVER...WILL NEED TO WATCH THESE BREAKS...ESPECIALLY THOSE OVER
S CENTRAL NY AND NE PA...WHICH MAY MOVE OVER DURING PEAK HEATING.
EVEN IF STORMS FAIL TO ORGANIZE...AND THIS REMAINS AN IF...DECENT
LLJ STILL APPARENT WITH 40-50 KT OFF THE DECK COULD SUPPORT GUSTY
WINDS WITH ANY -SHRA. NOT SEEING THE INVERTED V SOUNDING...BUT
DEWPOINT DEPRESSIONS CONTINUE TO INCREASE SO MAY SEE SOME OF THIS
ENERGY REACH THE SFC WITH AFTERNOON HEAVIER -SHRA. THIS WILL HAVE
TO BE WATCHED. ADJUSTED POPS/WX/SKIES TOWARD LATEST HRRR AND
RAP...WHICH SUPPORT THE THINKING FOR FURTHER DEVELOPMENT THIS
AFTERNOON.
PREVIOUS DISCUSSION...
AS THE LOW LEVEL JET MOVES EWD...DEEP LAYER MOISTURE AND LIFT
WILL RESULT IN NUMEROUS SHOWERS MOVING ACROSS THE REGION
TODAY...ALTHOUGH IT APPEARS THE SHOWERS WILL BE CONCENTRATED IN
THE WEST AND BECOME MORE FOCUSED IN SE NEW ENG LATE TODAY. THERE
IS ENOUGH ELEVATED INSTABILITY TO SUPPORT ISOLD TO SCT
THUNDERSTORMS TODAY. OF MORE CONCERN IS THE POTENTIAL FOR SFC
BASED INSTABILITY THIS AFTERNOON AHEAD OF THE COLD FRONT AS DEEP
LAYER SHEAR IS RATHER STRONG. MODELS SUGGEST MARGINAL SBCAPES LESS
THAN 1000 J/KG DEVELOPING ACROSS W NEW ENG. IT APPEARS THAT THE
SHOWERS AND CLOUD COVER WILL LIMIT INSTABILITY AND MID LEVEL LAPSE
RATES ARE ALSO UNFAVORABLE. SO WHILE WE CANT RULE OUT A
THUNDERSTORM WITH GUSTY WINDS IN THE WEST...THE MAIN THREAT WILL
BE LOCALLY HEAVY RAINFALL IN HIGH PWAT AIRMASS.
USED A BLEND OF MOS GUIDANCE FOR MAX TEMPS TODAY...GENERALLY
UPPER 60S TO LOWER 70S. IT WILL ALSO BE SOMEWHAT HUMID WITH
DEWPOINTS CLIMBING TO 60+. BREEZY SW WINDS DEVELOPING IN THE
COASTAL PLAIN THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
POSITION OF THE LOW LEVEL JET SUGGESTS SHOWERS AND ISOLD TSTMS
WILL BE WIDESPREAD ACROSS SE NEW ENG THIS EVENING WITH LESS
COVERAGE FURTHER WEST...THEN SHOWERS MOVE TO THE EAST OVERNIGHT
AS THE JET MOVES OFFSHORE. COLD FRONT MOVES INTO SNE OVERNIGHT
WITH DRIER MOVING IN BEHIND IT...MAINLY FOR WESTERN NEW ENG.
SUNDAY...
SFC FRONT STALLS ACROSS SNE DURING THE DAY. WITH MID LEVEL TROF
HANGING BACK TO THE WEST AND SHORTWAVE ENERGY ROTATING INTO NEW
ENG...THERE IS A POTENTIAL FOR RENEWED SHOWERS AND ISOLD
TSTMS...ESPECIALLY IN EASTERN NEW ENG WHERE BEST LOW LEVEL
CONVERGENCE WILL BE LOCATED. GUIDANCE INDICATES INSTABILITY WILL
BE LIMITED SO COVERAGE OF ANY TSTMS SHOULD BE ISOLATED. MAX TEMPS
SHOULD REACH UPPER 60S TO LOWER 70S...WARMEST IN RI AND SE MA.
COOLER AIRMASS NW ZONES IN POST FRONTAL AIRMASS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...
* COOLER AND DRIER WEATHER MONDAY AND TUESDAY
* MORE UNSETTLED WEATHER RETURNS MIDDLE OF NEXT WEEK
THE MODELS EXHIBIT GOOD AGREEMENT ON SYNOPTIC SCALE FEATURES
THROUGHOUT MUCH OF THE FORECAST PERIOD. HIGH PRESSURE BUILDS INTO
SOUTHERN NEW ENGLAND MONDAY AND TUESDAY AS LOW PRESSURE MOVES UP
THE COAST...PASSING EAST OF SOUTHERN NEW ENGLAND TUESDAY. SHOWERS
ARE POSSIBLE WEDNESDAY AHEAD OF A COLD FRONT THAT WILL MOVE
THROUGH THE AREA THURSDAY. THERE ARE SOME DIFFERENCES BETWEEN THE
GFS AND ECMWF TOWARDS THE END OF NEXT WEEK. THE EURO IS SLOWER
MOVING AN EAST COAST RIDGE OUT TO SEA WHILE THE GFS MOVES IT OUT
FAIRLY QUICKLY ALLOWING ANOTHER LOW PRESSURE SYSTEM TO AFFECT THE
AREA FRIDAY. GENERALLY WENT WITH A BLEND OF GUIDANCE FOR THE
FORECAST.
SUNDAY NIGHT THROUGH WEDNESDAY...HIGH PRESSURE STARTS TO BUILD
INTO THE EAST MONDAY AND TUESDAY AS LOW PRESSURE MOVES UP THE
COAST WELL EAST OF THE AREA INTO THE MARITIMES. THE HIGH PRESSURE
WILL MOVE OFFSHORE WEDNESDAY. MUCH OF THIS PERIOD IS EXPECTED TO
BE DRY... THOUGH A COLD CORE ALOFT WILL STEEPEN LAPSE RATES ENOUGH
THAT TOGETHER WITH DAYTIME HEATING COULD PRODUCE SOME DIURNAL
SHOWERS. BELOW AVERAGE TEMPERATURES ARE EXPECTED WITH MOSTLY SUNNY
SKIES. THE BIG IMPACT HERE WILL BE OVERNIGHT...WITH TEMPERATURES
EXPECTED TO DROP INTO THE 30S. WILL KEEP THE FROST WORDING IN THE
WEATHER GRIDS. MONDAY NIGHT LOOKS TO BE THE CHILLIEST NIGHT WITH
TEMPERATURES POSSIBLY DOWN TO FREEZING ACROSS PORTIONS OF THE
NORTHWESTERN ZONES.
THURSDAY AND FRIDAY...PLENTY OF UNCERTAINTY HERE WITH DIFFERENT
SYNOPTIC PATTERNS IN THE MODELS. THE ECMWF KEEPS THE UPPER LEVEL
RIDGE OVER THE EAST COAST A BIT LONGER THAN THE GFS. REGARDLESS...
THIS PERIOD LOOKS TO BE A BIT MORE UNSETTLED THAN EARLIER IN THE
WEEK. IT DOES LOOK AS THOUGH TEMPERATURES WILL RETURN TO NORMAL
OR POSSIBLY ABOVE NORMAL LEVELS THROUGH THE END OF THE WEEK.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...LOW CONFIDENCE ON CIG/VSBYS THROUGH TONIGHT.
TODAY...LINGERING IFR THIS MORNING...OTHERWISE MVFR CONDITIONS
EXPECTED AS SHOWERS MOVE ACROSS THE REGION FROM WEST TO EAST
TODAY. ISOLD TO SCT TSTMS POSSIBLE...ESPECIALLY WEST WITH LOCALLY
HEAVY RAIN AND GUSTY WINDS. SW WIND GUSTS TO 25 KT DEVELOPING THIS
AFTERNOON IN THE COASTAL PLAIN.
TONIGHT...SHOWERS AND ISOLD TSTMS WILL BECOME FOCUSED ACROSS SE
NEW ENG THIS EVENING. OTHERWISE...EXPECT IFR CONDITIONS TO
DEVELOP ACROSS MUCH OF THE REGION AS STRATUS AND PATCHY FOG
DEVELOPS.
SUN...CONDITIONS SHOULD IMPROVE TO VFR. BUT A FEW SHOWERS OR A
THUNDERSTORM POSSIBLE WHICH MAY BRING BRIEF MVFR ESPECIALLY E NEW
ENG.
KBOS TERMINAL...OVERALL LOW CONFIDENCE ON CIG FORECAST. WE HAVE
MAINLY VFR CIGS TODAY...LOWERING TO IFR TONIGHT. BUT LOWER CIGS
COULD DEVELOP EARLIER.
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR.
COULD SEE MVFR/IFR CONDITIONS IN DIURNAL SHOWERS EACH DAY.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
FORECAST CONFIDENCE HIGH THROUGH SUNDAY.
TODAY...INCREASING SW WINDS EXPECTED WITH GUSTS TO 25 KT
DEVELOPING AS THE LOW LEVEL JET MOVES INTO THE REGION. STRONG LOW
LEVEL INVERSION WILL LIMIT GUSTS AND EXPECT STRONGEST WINDS OVER
NEARSHORE WATERS. SEAS BUILDING OVER SOUTHERN WATERS. VSBY
REDUCED IN SHOWERS ESPECIALLY DURING THE AFTERNOON. ISOLATED
TSTMS LATE SAT.
TONIGHT...SW GUSTS TO 25 KT EARLY ACROSS EASTERN WATERS.
WIDESPREAD SHOWERS AND ISOLATED TSTMS. ROUGH SEAS SOUTH OCEAN
WATERS.
SUNDAY...ANOTHER PULSE OF SW WIND GUSTS TO 25 KT EXPECTED IN THE
AFTERNOON.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
EXPECT SEAS OF 5 TO 7 FEET ON THE OUTER WATERS SUNDAY NIGHT. SEAS
WILL DIMINISH MONDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS
OVER THE WATERS. SCA SEAS WILL CONTINUE ON THE OUTER WATERS
THROUGH MONDAY AFTERNOON. WESTERLY WINDS WILL FLIRT WITH SCA
CRITERIA SUNDAY NIGHT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ230>237-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...KJC/RLG
NEAR TERM...KJC/DOODY
SHORT TERM...KJC
LONG TERM...RLG
AVIATION...KJC/RLG
MARINE...KJC/RLG
AREA FORECAST DISCUSSION...CORRECTED
NWS MIAMI FL
210 PM EDT SAT MAY 11 2013
...CORRECTED LONG RANGE TIME FRAME...
.SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
SOUTH FLORIDA IS CURRENTLY UNDER NEAR ZONAL FLOW WITH A MID LEVEL
RIDGE TO THE EAST AND A LARGE CUT-OFF LOW OVER NORTHERN MEXICO. A
FAST MOVING WAVE IS EMBEDDED IN THE ZONAL FLOW PATTERN CURRENTLY
MOVING INTO THE FLORIDA PANHANDLE WITH A LARGE CLUSTER OF CONVECTION
ASSOCIATED WITH IT. THE PROXIMITY OF THIS WAVE ALONG WITH PLENTY OF
SUNSHINE EARLY TODAY AND INSTABILITY WILL CAUSE ANOTHER ROUND OF
LATE AFTERNOON AND EARLY EVENING THUNDERSTORMS DEVELOPING OVER THE
INTERIOR AND THEN WILL DRIFT BACK TOWARDS THE EAST COAST. AT THE
SURFACE, A RIDGE IS LOCATED ACROSS SOUTH FLORIDA PRODUCING A LOW
LEVEL SOUTHERLY FLOW WHICH WILL TEND TO KEEP THE INITIATION OF
CONVECTION WELL INLAND FROM THE COASTS OF MIAMI-DADE AND COLLIER
COUNTIES.
LOOKING UPSTREAM, A MAJOR MID LEVEL TROUGH WILL DEEPEN ACROSS
EASTERN NORTH AMERICA THROUGH MONDAY WITH ITS ASSOCIATED WEAKENING
COLD FRONT MOVING INTO NORTH FLORIDA ON SUNDAY AND INTO SOUTH
FLORIDA BY LATE MONDAY. THIS WILL PROVIDE A CONTINUED THREAT FOR
MAINLY AFTERNOON AND EVENING CONVECTION FAVORING THE INTERIOR AND
EAST COAST. FORECAST SOUNDINGS SHOW SLOW STORM MOTION AGAIN ON
SUNDAY BUT A STRONGER WESTERLY STEERING FLOW ON MONDAY AS THE TROUGH
DEEPENS FURTHER. THE PWAT IS ALSO FORECAST TO REMAIN IN THE RANGE OF
1.5-1.7 INCHES WHICH IS ABOVE THE AVERAGE FOR MID MAY. IN ADDITION,
500 MB TEMPERATURES ARE FORECAST TO HOVER AROUND -10 TO -11 CELSIUS
THROUGH MONDAY AND THIS IS ONE TO TWO DEGREES BELOW THE AVERAGE SO
ALSO ADDING FUEL TO THE MIX. THE COLD FRONT WILL PUSH OFF THE
SOUTHEAST COAST MONDAY EVENING AND BRING A REFRESHING FEELING TO
THE AIR WITH TEMPERATURES FALLING TO ABOUT 8-10 DEGREES BELOW
NORMAL MONDAY NIGHT.
.LONG TERM (TUESDAY THROUGH SATURDAY)... THE TROUGH WILL BEGIN TO
SHIFT EAST ON TUESDAY WITH A RIDGE BUILDING ACROSS THE GULF OF
MEXICO WHICH WILL FILTER A MUCH DRIER AIR MASS INTO SOUTH FLORIDA
CONTINUING THROUGH MUCH OF THE WEEK. THERE IS HOWEVER ONE
DISCREPANCY IN THE LONG RANGE MODELS BY THE END OF THE FORECAST.
BOTH THE ECMWF AND GFS SHOW THE CUT-OFF LOW CURRENTLY OVER
NORTHERN MEXICO TO BEGIN LIFTING EASTWARD BY THE MIDDLE OF THE
WEEK. HOWEVER, THE 00Z RUN OF THE ECMWF SHOWS THIS LOW SHIFTING
NEARLY DUE EAST AND ACROSS NORTH FLORIDA BY FRIDAY AND SATURDAY
WHICH WOULD TEND TO DESTABILIZE SOUTH FLORIDA ONCE AGAIN WHILE THE
LAST FEW RUNS OF THE GFS HAVE SHOWN THE LOW LIFTING MORE TO THE
NORTHEAST WELL NORTH OF THE PENINSULA. THE 12Z RUN HAS SHIFTED A
TAD FARTHER TO THE SOUTH BUT WILL WAIT FOR MORE CONSISTENT RUNS
BEFORE ADJUSTING THE FORECAST KEEPING IT DRY FOR NOW INTO NEXT
WEEKEND.
&&
.AVIATION...
SHRAS/TSRAS ALREADY BEGINNING TO DEVELOP ACROSS INTERIOR SECTIONS OF
PALM BEACH...BROWARD...AND MIAMI-DADE COUNTIES EARLY THIS AFTERNOON.
THIS ACTIVITY WILL CONTINUE THROUGH THE LATE AFTERNOON AND EARLY
EVENING HOURS MUCH LIKE YESTERDAY. LATEST HRRR DEPICTS FURTHER
ACTIVITY DEVELOPING ACROSS THE INTERIOR OVER THE NEXT FEW HOURS AND
PUSHING EAST AS A RESULT OF THE GULF BREEZE THAT IS ALREADY WELL
ESTABLISHED. PLACED VCTS AT ALL EAST COAST TERMINAL SITES EXCEPT FOR
KTMB THROUGH THE EARLY EVENING HOURS. ACTIVITY SHOULD QUICKLY
DIMINISH WITH LOSS OF HEATING. FLOW SHOULD THEN GENERALLY BE
SOUTHERLY AND LIGHT OVERNIGHT.
&&
.MARINE...
TRANQUIL WIND AND SEAS WILL CONTINUE THROUGH THE WEEKEND OUTSIDE
OF ISOLATED STRONG CONVECTION. A COLD FRONT WILL MOVE ACROSS THE
SOUTH FLORIDA WATERS LATE MONDAY WITH STRONG HIGH PRESSURE
BUILDING BEHIND THE FRONT WITH INCREASING WIND AND SEAS MONDAY
NIGHT INTO MID WEEK.
&&
.FIRE WEATHER...
NO PROBLEMS OR CONCERNS WITH AMPLE TROPICAL MOISTURE THROUGH MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 86 73 85 / 30 50 30 30
FORT LAUDERDALE 77 86 74 85 / 30 50 20 50
MIAMI 76 87 75 87 / 30 40 20 50
NAPLES 73 87 73 85 / 20 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...30/KOB
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS MIAMI FL
207 PM EDT SAT MAY 11 2013
.SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
SOUTH FLORIDA IS CURRENTLY UNDER NEAR ZONAL FLOW WITH A MID LEVEL
RIDGE TO THE EAST AND A LARGE CUT-OFF LOW OVER NORTHERN MEXICO. A
FAST MOVING WAVE IS EMBEDDED IN THE ZONAL FLOW PATTERN CURRENTLY
MOVING INTO THE FLORIDA PANHANDLE WITH A LARGE CLUSTER OF CONVECTION
ASSOCIATED WITH IT. THE PROXIMITY OF THIS WAVE ALONG WITH PLENTY OF
SUNSHINE EARLY TODAY AND INSTABILITY WILL CAUSE ANOTHER ROUND OF
LATE AFTERNOON AND EARLY EVENING THUNDERSTORMS DEVELOPING OVER THE
INTERIOR AND THEN WILL DRIFT BACK TOWARDS THE EAST COAST. AT THE
SURFACE, A RIDGE IS LOCATED ACROSS SOUTH FLORIDA PRODUCING A LOW
LEVEL SOUTHERLY FLOW WHICH WILL TEND TO KEEP THE INITIATION OF
CONVECTION WELL INLAND FROM THE COASTS OF MIAMI-DADE AND COLLIER
COUNTIES.
LOOKING UPSTREAM, A MAJOR MID LEVEL TROUGH WILL DEEPEN ACROSS
EASTERN NORTH AMERICA THROUGH MONDAY WITH ITS ASSOCIATED WEAKENING
COLD FRONT MOVING INTO NORTH FLORIDA ON SUNDAY AND INTO SOUTH
FLORIDA BY LATE MONDAY. THIS WILL PROVIDE A CONTINUED THREAT FOR
MAINLY AFTERNOON AND EVENING CONVECTION FAVORING THE INTERIOR AND
EAST COAST. FORECAST SOUNDINGS SHOW SLOW STORM MOTION AGAIN ON
SUNDAY BUT A STRONGER WESTERLY STEERING FLOW ON MONDAY AS THE TROUGH
DEEPENS FURTHER. THE PWAT IS ALSO FORECAST TO REMAIN IN THE RANGE OF
1.5-1.7 INCHES WHICH IS ABOVE THE AVERAGE FOR MID MAY. IN ADDITION,
500 MB TEMPERATURES ARE FORECAST TO HOVER AROUND -10 TO -11 CELSIUS
THROUGH MONDAY AND THIS IS ONE TO TWO DEGREES BELOW THE AVERAGE SO
ALSO ADDING FUEL TO THE MIX. THE COLD FRONT WILL PUSH OFF THE
SOUTHEAST COAST MONDAY EVENING AND BRING A REFRESHING FEELING TO
THE AIR WITH TEMPERATURES FALLING TO ABOUT 8-10 DEGREES BELOW
NORMAL MONDAY NIGHT.
.LONG TERM (TUESDAY THROUGH SUNDAY)...
THE TROUGH WILL BEGIN TO SHIFT EAST ON TUESDAY WITH A RIDGE BUILDING
ACROSS THE GULF OF MEXICO WHICH WILL FILTER A MUCH DRIER AIR MASS
INTO SOUTH FLORIDA CONTINUING THROUGH MUCH OF THE WEEK. THERE IS
HOWEVER ONE DISCREPANCY IN THE LONG RANGE MODELS BY THE END OF THE
FORECAST. BOTH THE ECMWF AND GFS SHOW THE CUT-OFF LOW CURRENTLY
OVER NORTHERN MEXICO TO BEGIN LIFTING EASTWARD BY THE MIDDLE OF
THE WEEK. HOWEVER, THE 00Z RUN OF THE ECMWF SHOWS THIS LOW
SHIFTING NEARLY DUE EAST AND ACROSS NORTH FLORIDA BY FRIDAY AND
SATURDAY WHICH WOULD TEND TO DESTABILIZE SOUTH FLORIDA ONCE AGAIN
WHILE THE LAST FEW RUNS OF THE GFS HAVE SHOWN THE LOW LIFTING MORE
TO THE NORTHEAST WELL NORTH OF THE PENINSULA. THE 12Z RUN HAS
SHIFTED A TAD FARTHER TO THE SOUTH BUT WILL WAIT FOR MORE
CONSISTENT RUNS BEFORE ADJUSTING THE FORECAST KEEPING IT DRY FOR
NOW INTO NEXT WEEKEND.
&&
.AVIATION...
SHRAS/TSRAS ALREADY BEGINNING TO DEVELOP ACROSS INTERIOR SECTIONS OF
PALM BEACH...BROWARD...AND MIAMI-DADE COUNTIES EARLY THIS AFTERNOON.
THIS ACTIVITY WILL CONTINUE THROUGH THE LATE AFTERNOON AND EARLY
EVENING HOURS MUCH LIKE YESTERDAY. LATEST HRRR DEPICTS FURTHER
ACTIVITY DEVELOPING ACROSS THE INTERIOR OVER THE NEXT FEW HOURS AND
PUSHING EAST AS A RESULT OF THE GULF BREEZE THAT IS ALREADY WELL
ESTABLISHED. PLACED VCTS AT ALL EAST COAST TERMINAL SITES EXCEPT FOR
KTMB THROUGH THE EARLY EVENING HOURS. ACTIVITY SHOULD QUICKLY
DIMINISH WITH LOSS OF HEATING. FLOW SHOULD THEN GENERALLY BE
SOUTHERLY AND LIGHT OVERNIGHT.
&&
.MARINE...
TRANQUIL WIND AND SEAS WILL CONTINUE THROUGH THE WEEKEND OUTSIDE
OF ISOLATED STRONG CONVECTION. A COLD FRONT WILL MOVE ACROSS THE
SOUTH FLORIDA WATERS LATE MONDAY WITH STRONG HIGH PRESSURE
BUILDING BEHIND THE FRONT WITH INCREASING WIND AND SEAS MONDAY
NIGHT INTO MID WEEK.
&&
.FIRE WEATHER...
NO PROBLEMS OR CONCERNS WITH AMPLE TROPICAL MOISTURE THROUGH MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 86 73 85 / 30 50 30 30
FORT LAUDERDALE 77 86 74 85 / 30 50 20 50
MIAMI 76 87 75 87 / 30 40 20 50
NAPLES 73 87 73 85 / 20 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...30/KOB
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS MIAMI FL
957 AM EDT SAT MAY 11 2013
.UPDATE...
CHANGES ARE NOT BEING PLANNED FOR THE MORNING UPDATES AT THIS
TIME. CONVECTIVE PARAMETERS LOOK SIMILAR TO YESTERDAY WITH SOME
MINOR FLUCTUATIONS. A MID LAYER INVERSION REMAINS ALTHOUGH IT IS
AT A LOWER LEVEL AROUND 700 MB VERSUS 500 MB FROM YESTERDAY
MORNING. STILL, THE LOW LEVELS REMAIN QUITE UNSTABLE SO THIS WOULD
SUGGEST THAT DEEP CONVECTION WILL ONCE AGAIN BE DELAYED. THIS ALSO
IS WHAT THE HRRR IS DEPICTING WITH STRONG CONVECTIVE ACTIVITY
DEVELOPING AROUND THE 20-21Z TIME FRAME. STORM MOTION WILL AGAIN
BE VERY SLOW WITH A DRIFT TOWARDS THE EAST. THE MAX CAPE TODAY IS
A LITTLE LOWER AT LESS THAN 2000 J/KG BUT THE 500 MB TEMPERATURE
COOLED BY 1 DEGREE CELSIUS WHICH OFFSETS THE INSTABILITY. SO ALL
THINGS CONSIDERED, FORECAST WILL REMAIN UNCHANGED.
KOB
&&
.PREV DISCUSSION... /ISSUED 818 AM EDT SAT MAY 11 2013/
AVIATION...
GENERALLY...VFR CONDITIONS WILL PREVAIL THROUGH THE WEEKEND. MOSTLY
CLEAR SKIES AND CALM WINDS EARLY THIS MORNING WILL GIVE WAY TO
INCREASING CUMULUS AND SOUTHEAST WINDS AT 10-15 KTS. SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND
PERSIST THROUGH EARLY EVENING. CURRENT CONFIDENCE IN TIMING/LOCATION
OF CONVECTION IS NOT HIGH...SO HAVE ONLY PLACED VCSH IN TAFS FOR 12Z
ISSUANCE. BEST CHANCE OF THUNDERSTORMS IS KPBI AND RISK OF SHOWERS
ARE LOWEST IN KAPF...WHERE POP BELOW 20 PERCENT DIDNT WARRANT
MENTION IN TAF. ANY THUNDERSTORMS COULD HAVE GUSTY WINDS AND
SIGNIFICANT BUT BRIEF FLIGHT RESTRICTIONS. THIS EVENING...ACTIVITY
SHOULD DIMINISH AND A RETURN TO MOSTLY CLEAR SKIES AND LIGHT WINDS.
PREV DISCUSSION... /ISSUED 411 AM EDT SAT MAY 11 2013/
DISCUSSION...
WATER VAPOR AND NAM ANALYSIS FROM THIS MORNING SHOWED AN UPPER
RIDGE STRETCHING FROM THE SOUTHERN GULF AND WESTERN CARIBBEAN
NORTHEASTWARD OVER SOUTH FLORIDA INTO THE WESTERN ATLANTIC. AN
UPPER LEVEL TROUGH WAS DIGGING INTO THE PLAINS...AND A CUT OFF
UPPER LOW REMAINED OVER BAJA CALIFORNIA AND WESTERN MEXICO. AT THE
SURFACE...THE RIDGE REMAINED OVER THE WESTERN ATLANTIC...WITH THE
RIDGE AXIS OVER NORTH CENTRAL FLORIDA.
THE UPPER LEVEL RIDGE WILL SHIFT EAST AND FLATTEN OUT OVER SOUTH
FLORIDA TODAY AS THE UPPER LEVEL TROUGH DIGS INTO THE SOUTHEAST.
TEMPERATURES AT 500MB AND ABOVE WILL WARM TODAY...SO THE HAIL
THREAT WILL BE SLIGHTLY LOWER THAN ON FRIDAY. HOWEVER...0-6KM
SHEAR WILL INCREASE TO AROUND 30 KNOTS...WITH SOMEWHAT DRIER AIR
IN THE MID LEVELS. SO THE WIND THREAT MAY ACTUALLY BE
HIGHER...WITH STRONG TO ISOLATED SEVERE STORMS POSSIBLE. SPC HAS
ALSO ADDED THE EAST COAST IN 5 PERCENT WIND AND HAIL THREAT FOR
TODAY. THE FLOW AT 850MB AND ABOVE WILL BE LIGHT OUT OF THE WEST
TO NORTHWEST. SO STORMS WILL FORM CLOSER TO THE EAST COAST...AND
MOVE BACK TOWARDS THE EAST COAST THIS AFTERNOON. STORM MOTION WILL
BE SLOW...SO LOCALLY HEAVY RAINFALL IS POSSIBLE WHERE STORMS
DEVELOP. MODELS INDICATE DECENT AMOUNTS OF QPF...BUT POP GUIDANCE
IS 20-30 PERCENT. THE POP GUIDANCE HAS BEEN WAY TOO LOW THE PAST
SEVERAL DAYS...SO WENT ABOVE GUIDANCE THE NEXT SEVERAL DAYS...IN
THE 30-50 PERCENT RANGE ACROSS THE INTERIOR AND EAST.
AN MCS IS SUPPOSED TO DEVELOP ACROSS THE NORTH CENTRAL GULF THIS
AFTERNOON AND TRACK EAST INTO NORTHERN AND CENTRAL FLORIDA LATE
THIS AFTERNOON. MODELS DO NOT HANDLE THESE FEATURES ALL THAT
WELL...SO IT IS POSSIBLE THE TAIL END OF THE SHOWERS AND STORMS
COULD MOVE INTO THE OFFSHORE GULF WATERS LATE THIS AFTERNOON INTO
THE EVENING...SO HAVE SLIGHT CHANCE POPS FOR THIS POSSIBILITY.
SHOWERS AND THUNDERSTORMS ACROSS THE EASTERN HALF OF THE AREA WILL
WIND DOWN THIS EVENING WITH THE LOSS OF DAYTIME HEATING. TEMPS
WILL BE WARM TODAY AND TONIGHT...WITH HIGHS IN THE MID 80S TO
LOWER 90S AND LOWS IN THE MID 60S TO MID 70S.
A COLD FRONT WILL MOVE INTO NORTHERN FLORIDA ON SUNDAY. FLOW ALOFT
WILL BE LIGHT OUT OF THE WEST...SO STORMS WILL CONCENTRATE ACROSS
THE INTERIOR AND TOWARDS THE EAST COAST. TEMPS ALOFT WILL WARM
SLIGHTLY...AND SHEAR WILL BE LESS...BUT THERE COULD BE SOME STRONG
STORMS. TEMPS WILL REMAIN SIMILAR TO SATURDAY.
THE UPPER LEVEL TROUGH WILL DIG DOWN INTO THE FLORIDA PENINSULA ON
MONDAY...AND THE FRONT WILL ALSO MOVE INTO SOUTH FLORIDA. THE
REGION WILL ALSO BE IN THE RIGHT ENTRANCE REGION OF 90-100KT JET
STREAK. THE GFS IS INDICATING 30 KT 0-6KM BULK SHEAR IN THE
AFTERNOON. HOWEVER...CAPE IS EXPECTED TO BE MUCH LOWER THAN THE
OVER THE WEEKEND. SO THE BEST CHANCE OF STORMS WILL BE ACROSS THE
NORTH AND NORTHEAST IN THE MORNING TO EARLY AFTERNOON...AND THEN
ACROSS THE SOUTHEAST AND ESPECIALLY MIAMI-DADE COUNTY IN THE
AFTERNOON.
COOLER AND MUCH DRIER AIR WILL THEN MOVE INTO THE REGION MONDAY
NIGHT AND TUESDAY...AND CONDITIONS WILL REMAIN MOSTLY DRY THROUGH
THE END OF THE WEEK. HIGH PRESSURE WILL BUILD INTO THE SOUTHEAST
AND WESTERN ATLANTIC TUESDAY...WITH INCREASING NORTHEASTERLY FLOW
OVER THE LOCAL WATERS. HIGH TEMPERATURES ARE EXPECTED TO ONLY BE
IN THE LOW TO MID 80S THROUGH THE END OF WEEK. LOW TEMPERATURES
WILL DROP OFF INTO THE 50S ACROSS THE INTERIOR EACH NIGHT...WITH
60S TO AROUND 70 DEGREES FOR THE METRO AREAS.
MARINE...
MOSTLY SOUTHEAST TO SOUTH WIND THROUGH THE WEEKEND AT LESS THAN 15
KNOTS WITH SEAS LESS THAN 3 FEET. HIGH PRESSURE BEGINS TO BUILD
NORTH OF THE REGION EARLY NEXT WEEK WITH WINDS AND SEAS BUILDING
BUT REMAINING BELOW ADVISORY CRITERIA.
FIRE WEATHER...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH AFTERNOON
THIS WEEKEND ACROSS THE INTERIOR AND TOWARDS THE EAST COAST.
MINIMUM RELATIVE HUMIDITY VALUES WILL REMAIN WELL ABOVE CRITICAL
VALUES EACH DAY THIS WEEKEND. DRIER AIR WILL BEGIN TO FILTER INTO
THE REGION MONDAY AFTERNOON...AND MINIMUM RELATIVE HUMIDITY VALUES
ARE EXPECTED TO BE NEAR 35 PERCENT ACROSS THE NORTHWEST INTERIOR
TUESDAY AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 87 73 87 71 / 40 30 50 30
FORT LAUDERDALE 87 72 87 74 / 40 30 50 20
MIAMI 89 74 88 73 / 40 30 40 20
NAPLES 87 72 85 71 / 10 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
652 AM EDT Sat May 11 2013
.NEAR TERM [through This Afternoon]...
Updated at: 650 AM EDT
The overall progression of the weather elements in the near term
appears to be on track. The HRRR and RAP continue to perform best
with the position and timing of upstream convective activity. We
still expect rain and some thunderstorms to gradually spread into
the western part of our area around 16 UTC, and then affect the rest
of the area through the remainder of the afternoon. The best chances
for rain still appear to be in the Florida Panhandle and Big Bend,
and the immediate adjacent row of counties in south Georgia. Thus,
no major changes were made - although the thinking with respect to
severe weather potential has changed slightly.
Objective analysis continues to show a pseudo-warm front or surface
pressure trough from just off the Louisiana coast to near our
offshore buoy (42039). This is supported by a noticeable thetae
gradient and wind shift offshore. Not surprisingly, this is also the
zone where the strongest convection has been developing upstream.
Given the current position of the mesoscale boundary offshore, we
may see the most intense storms today focused over the coastal
waters. This is a theory that is supported by recent high-resolution
model runs, with strongest average updraft strengths over the Gulf.
Therefore, most of our land areas could just see some general rain
showers with some embedded thunderstorms.
However, we still have to be wary of several scenarios that could
bring stronger thunderstorms to our land areas. First, the boundary
could surge north into the Florida Big Bend, which would support an
isolated severe weather threat in our Florida zones east of the
Apalachicola River. Second, the eastern part of our area could
receive greater insolation and heating ahead of the advancing cirrus
shield from the upstream convection. This could support a ribbon of
greater instability east of a line from AAF-ABY, and scattered
storms could develop in the weakly capped environment as large scale
forcing increases ahead of the advancing mid-level MCV associated
with the current convection near coastal Louisiana. Either way, the
situation still seems to indicate a threat for isolated strong or
severe storms - but mainly in southern and eastern areas.
&&
.SHORT TERM [Tonight through Monday]...
The 00 UTC NWP guidance continues to forecast an unusually deep
longwave trough over the eastern CONUS Sunday and Monday. The PoP
will decrease from northwest to southeast Sunday as dry air
advection develops. The highest PoP, 30-40%, will be from
Tallahassee southward and eastward tonight and Sunday, with the PoP
decreasing below 10% Sunday evening. The core of the cooler and
drier airmass won`t reach our forecast area until Monday. Highs on
Sunday will be in the lower 80s, but only in the 70s (below average)
Monday. Lows on Monday morning will be in the 50s (also below
average). The low humidity and relatively breezy conditions on
Monday will make it feel quite pleasant for mid May, when it usually
begins to get warm and humid.
&&
.LONG TERM [Monday Night through Friday]...
Deep layer ridging will build into the region for the middle of the
week followed by a low amplitude trough late Thursday into
Friday. There will be a slight to low end chance of rain on
Friday, otherwise the extended period will be dry. The week will
begin with below normal temperatures and gradually moderate to
seasonal levels by Thursday. The coldest temperatures will be
Tuesday morning when upper 40s to around 50 degrees are forecast.
&&
.AVIATION [Through 12 UTC Sunday]...
Updated at: 650 AM EDT
Mid-high level cloud cover has cleared out, leading to some patchy
fog and low stratus across the area around sunrise. This is most
established at DHN and ECP where CIGS are near or below airport
minimums. Elsewhere, flight categories should remain in the MVFR or
IFR range. Fog and low stratus should generally lift by mid morning.
Rain will spread into the area from west to east, first affecting
DHN and ECP around 16 UTC. There may be a few thunderstorms, but
confidence was not high enough to include in a prevailing group.
Scattered storms would be most likely between 18-00 UTC at TLH and
VLD. Low CIGS may develop again tonight. For now kept things MVFR.
&&
.MARINE...
Aside from the increased rain chances, weekend boaters will be
treated to low winds and seas (outside of scattered thunderstorms).
This will change Sunday night as the rather strong area of high
pressure builds across the Southeast behind a cold front, causing
winds to increase to 15 to 20 KT. These offshore winds may remain at
exercise caution levels through Tuesday morning.
&&
.FIRE WEATHER...
Wetting rains are expected over a good portion of the area today.
Drier air will arrive behind a cold front on Sunday Night with very
low RH for May expected on Monday. Despite the minimum RH around
25%, other fuel-dependent red flag criteria may not be met. Thus,
while red flag conditions seem somewhat uncertain, there is high
confidence that Monday will be a breezy, dry day with high
dispersion values.
&&
.HYDROLOGY...
The 00 UTC WPC 5-day rainfall accumulation forecast continues to
show our between one half and one inch over our forecast area,
mainly this weekend, and with the highest totals west of
Tallahassee. None of the experimental hydrologic ensembles forecast
minor flooding for our river forecast points over the next several
days. The maximum of maximum 6-hour QPF amounts from the various
Convection Allowing Models (CAM), a worst case scenario, show
isolated narrow bands of 3-4 inches. Neither the area coverage or
magnitude of these values would indicate enough of a threat for a
flash flood watch for today`s rain.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 83 66 82 53 80 / 70 40 30 10 0
Panama City 77 67 81 57 78 / 70 40 20 10 0
Dothan 81 63 79 50 78 / 70 40 10 0 0
Albany 85 64 81 50 76 / 60 40 10 0 0
Valdosta 86 64 81 52 77 / 70 40 30 10 0
Cross City 84 66 82 57 80 / 40 30 40 10 0
Apalachicola 79 67 79 59 76 / 60 30 30 10 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Lamers
SHORT TERM...Fournier
LONG TERM...Barry
AVIATION...Lamers
MARINE...Fournier
FIRE WEATHER...Lamers
HYDROLOGY...Fournier
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
352 AM EDT Sat May 11 2013
.NEAR TERM [Today]...
The forecast today remains somewhat uncertain as much will depend on
the mesoscale evolution over the next 6-12 hours. The surface
pattern is quite muddled due to upstream MCS activity from Texas to
coastal Louisiana in the past day or two. Objective analysis places
a surface trough and convergence zone along the Louisiana coast,
extending east into the coastal waters adjacent to the FL Panhandle
coastline. Thunderstorms have developed early this morning just
north of the richer surface thetae (likely elevated slightly), and
ahead of an advancing mid-level MCV over coastal SW Louisiana. The
vast majority of both global and convection-allowing models (CAM)
had indicated a focused area of QPF near coastal Louisiana in the
12-18 UTC time frame, which means that things appear to be "ahead of
schedule" by a few hours. The model that seems to most closely
resemble reality right now (at 07 UTC) is the HRRR. Therefore, the
progression of PoPs and temperature trends closely follow the HRRR
and RAP models. For the forecast, this means we began increasing
rain chances in the western part of our area around 16-18 UTC
(around the noon hour), with an eastward progression from there
during the afternoon hours. High temperatures were kept highest in
the east, where cloud cover and rain will be last to arrive.
With respect to the intensity of thunderstorms, there is also a bit
of uncertainty. The initial SPC SWODY1 places us in 5% probabilities
of severe hail and wind. This seems reasonable given a lack of
clarity in the mesoscale details. The best chances of seeing a
strong or severe storm look to be where any sort of heating is able
to occur before cloud cover increases. In most of the available
models, areas that are able to get heating in the morning see about
1000-1500 j/kg of CAPE in the afternoon, with around 25-30 knots of
0-6km shear. It is in these favorable intersections of instability
and shear where a severe storm or two would be most likely. Impacts
would probably be rather isolated though. Assuming dewpoints in at
least the mid-60s, surface based (and the strongest) storms would be
most likely in areas that can get into the 80s temperature-wise.
&&
.SHORT TERM [Tonight through Monday]...
The 00 UTC NWP guidance continues to forecast an unusually deep
longwave trough over the eastern CONUS Sunday and Monday. The PoP
will decrease from northwest to southeast Sunday as dry air
advection develops. The highest PoP, 30-40%, will be from
Tallahassee southward and eastward tonight and Sunday, with the PoP
decreasing below 10% Sunday evening. The core of the cooler and
drier airmass won`t reach our forecast area until Monday. Highs on
Sunday will be in the lower 80s, but only in the 70s (below average)
Monday. Lows on Monday morning will be in the 50s (also below
average). The low humidity and relatively breezy conditions on
Monday will make it feel quite pleasant for mid May, when it usually
begins to get warm and humid.
&&
.LONG TERM [Monday Night through Friday]...
Deep layer ridging will build into the region for the middle of the
week followed by a low amplitude trough late Thursday into
Friday. There will be a slight to low end chance of rain on
Friday, otherwise the extended period will be dry. The week will
begin with below normal temperatures and gradually moderate to
seasonal levels by Thursday. The coldest temperatures will be
Tuesday morning when upper 40s to around 50 degrees are forecast.
&&
.AVIATION [Through 06 UTC Sunday]...
As some mid-high level cloud cover clears out of our area for the
last half of the overnight period (06-12 UTC), we are expecting some
patchy fog or low stratus to develop, with periodic reductions to
MVFR or IFR. Conditions should improve around 13-14 UTC. After that,
the outlook is VFR, although there may be some thunderstorms today
moving into the area from the west. Timing looks to be beginning
around 16-19 UTC at ECP and DHN, to as late as 21-00 UTC at VLD. In
any of the thunderstorms, brief reductions in the flight categories
would be expected, as well as the possibility of some gusty winds.
However, confidence in timing and location of storms is not high
enough to include in prevailing or TEMPO groups at this time.
&&
.MARINE...
Aside from the increased rain chances, weekend boaters will be
treated to low winds and seas (outside of scattered thunderstorms).
This will change Sunday night as the rather strong area of high
pressure builds across the Southeast behind a cold front, causing
winds to increase to 15 to 20 KT. These offshore winds may remain at
exercise caution levels through Tuesday morning.
&&
.FIRE WEATHER...
Wetting rains are expected over a good portion of the area today.
Drier air will arrive behind a cold front on Sunday Night with very
low RH for May expected on Monday. Despite the minimum RH around
25%, other fuel-dependent red flag criteria may not be met. Thus,
while red flag conditions seem somewhat uncertain, there is high
confidence that Monday will be a breezy, dry day with high
dispersion values.
&&
.HYDROLOGY...
The 00 UTC WPC 5-day rainfall accumulation forecast continues to
show our between one half and one inch over our forecast area,
mainly this weekend, and with the highest totals west of
Tallahassee. None of the experimental hydrologic ensembles forecast
minor flooding for our river forecast points over the next several
days. The maximum of maximum 6-hour QPF amounts from the various
Convection Allowing Models (CAM), a worst case scenario, show
isolated narrow bands of 3-4 inches. Neither the area coverage or
magnitude of these values would indicate enough of a threat for a
flash flood watch for today`s rain.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 83 66 82 53 80 / 70 40 30 10 0
Panama City 77 67 81 57 78 / 70 40 20 10 0
Dothan 81 63 79 50 78 / 70 40 10 0 0
Albany 85 64 81 50 76 / 60 40 10 0 0
Valdosta 86 64 81 52 77 / 70 40 30 10 0
Cross City 84 66 82 57 80 / 40 30 40 10 0
Apalachicola 79 67 79 59 76 / 60 30 30 10 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Lamers
SHORT TERM...Fournier
LONG TERM...Barry
AVIATION...Lamers
MARINE...Fournier
FIRE WEATHER...Lamers
HYDROLOGY...Fournier
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
139 PM EDT SAT MAY 11 2013
.PREV DISCUSSION... /ISSUED 1045 AM EDT SAT MAY 11 2013/
UPDATE...
COLD FRONT IS CURRENTLY SITUATED FROM THE EASTERN GREAT LAKES
THROUGH THE MIDDLE ATLANTIC TO THE CENTRAL GULF COAST. THE FRONT
WILL CONTINUE TO MOVE EASTWARD THROUGH THE DAY AND THROUGH THE
REMAINDER OF THE CWFA THIS EVENING/OVERNIGHT.
EARLIER ADJUSTMENTS TO THE GRIDS INCLUDED SOME FINE TUNING OF THE
CLOUD COVER...POPS...AND HOURLY TEMPS/DEWPOINTS. MAX TEMPS LOOK
GOOD FOR NOW. MAIN FORECAST PROBLEM OF THE DAY WILL BE POPS.
SIGNIFICANT CLOUD COVER WILL HELP KEEP SURFACE INSTABILITY
MARGINAL UNDERCUTTING SURFACE HEATING. IN ADDITION...CONVECTION
ALONG THE GULF COAST MAY DISRUPT THE MOISTURE FLOW NORTHWARD.
NAM...GFS...ETC DONT HAVE A REALLY GOOD HANDLE OF THE GULF
CONVECTION. HOWEVER...THE LATEST RUN OF THE HRRR SEEMS TO HANDLE
THE CONVECTION REASONABLY. DO THINK SCT STORMS WILL DEVELOP ALONG
THE FRONT LATER IN THE AFTERNOON...MOSTLY SHOWERS WITH A FEW
THUNDERSTORMS. MAY END UP HAVING TO REDUCE POPS IN THE SOUTH TO
CHANCE...IF THEY GULF CONVECTION CONTINUES TO HOLD TOGETHER.
PREV DISCUSSION... /ISSUED 747 AM EDT SAT MAY 11 2013/
PREV DISCUSSION... /ISSUED 447 AM EDT SAT MAY 11 2013/
SHORT TERM /TODAY THROUGH SUNDAY/...
CURRENT SATELLITE LOOP SHOWS A LARGE MOISTURE PLUME EXTENDING FROM
THE NEW ENGLAND STATES...DOWN THE EASTERN SEABOARD...AND OVER TO THE
TX GULF COAST. THERE IS A NICE AREA OF ENHANCED SHOWERS AND ISOLATED
THUNDERSTORMS ACROSS TN AND AL BUT THIS PRECIPITATION IS NOT
EXPECTED TO MAKE IT INTO GA UNTIL LATER THIS MORNING INTO THIS
AFTERNOON. THE ACTUAL FRONT ASSOCIATED WITH THIS MOISTURE PLUME IS
BACK ACROSS TN NEAR MEMPHIS AND IT IS MOVING SLOWLY EAST. THIS FRONT
IS EXPECTED TO PUSH INTO NW GA BY 18Z TODAY AND MOVE SOUTH AND EAST
THROUGH THE SHORT TERM. IT SHOULD FINALLY PUSH OFF THE GA COAST BY
18Z SUN. AS THIS FRONT MOVES INTO THE AREA IT WILL BRING INCREASED
MOISTURE AND ACT AS A CATALYST FOR SHRA/TSRA DEVELOPMENT TODAY AND
TONIGHT. INSTABILITIES INCREASE TODAY WITH CAPES GETTING INTO THE
1000-1500 J/KG RANGE AND LIS GETTING DOWN INTO THE -1 TO -3 RANGE BY
18Z-00Z. SHEAR IS EXPECTED TO BE VERY WEAK AND LAPSE RATES ARE NOT
THAT IMPRESSIVE EITHER SO NOT EXPECTING ANY SEVERE STORMS TODAY.
ONCE THIS FRONT MOVES EAST OF THE AREA...A MUCH DRIER AIRMASS MOVES
IN WITH DEWPOINTS IN THE UPPER 30S TO LOWER 40S EXPECTED BY 18Z SUN.
01
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
GFS/ECMWF MODEL GUIDANCE ARE IN GOOD AGREEMENT WITH A BROAD UPPER
UPPER LEVEL TROUGH MOVING THROUGH THE EASTERN U.S. THROUGH MON.
SURFACE HIGH PRESSURE WILL BUILD INTO GA WITH GENERALLY CLEAR
SKIES AND VERY DRY AND COOL AIR ALLOWING TEMPERATURES TO PLUNGE
ONCE AGAIN. AT THIS TIME SUN NIGHT MINS SHOULD BE FROM 10-15
DEGREES BELOW NORMAL WHILE MON MAXES WILL BE AROUND 10 DEGREES
BELOW NORMAL. A RAPID WARM-UP IS EXPECTED TUE THROUGH THU AS AN
UPPER LEVEL RIDGE DEVELOPS AND MOVES INTO THE SOUTHEAST U.S. MIN
AND MAX TEMPERATURES DURING THIS PERIOD WILL RETURN TO NEAR OR A
FEW DEGREES ABOVE NORMAL. THE GFS AND ECMWF MODELS BEGIN TO DIFFER
IN THEIR SOLUTIONS FOR THE END OF THE WEEK. THE GFS DEPICTS A MORE
ORGANIZED COLD FRONT MOVING THROUGH THE TN VALLEY THU NIGHT AND
FRI WHILE THE ECMWF HAS A WEAK PRESSURE PATTERN ALOFT. WILL GO
WITH THE GFS FOR NOW INDICATING ISOLATED TO SCATTERED TSTMS WITH
THE DIURNAL HEATING ON THU BECOMING MORE INFLUENCED BY THE
APPROACHING FRONT ON FRIDAY.
16
&&
.AVIATION...
18Z UPDATE...
COLD FRONT CURRENTLY ACROSS CENTRAL AL WILL MOVE ACROSS THE METRO
AREA LATER THIS EVENING. A WIND SHIFT TO THE NW SHOULD OCCUR JUST
BEFORE 06Z. WINDS MAY GUST TO AROUND 20 KT TOMORROW AFTERNOON AT
KATL. SCT SHRA EXPECTED FOR THE REMAINDER OF THE AFTERNOON TO
SKIRT THE AIRPORT. BEST CHANCE FOR THUNDER SEEMS TO BE FROM 22Z TO
00Z. VFR CONDITIONS EXPECTED ON MONDAY.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON TSRA TIMING AND CIGS THIS AFT/EVE. HIGH
CONFIDENCE REMAINING ELEMENTS/TIMES.
NLISTEMAA
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 79 56 77 43 / 50 30 5 0
ATLANTA 76 55 73 46 / 50 30 5 0
BLAIRSVILLE 72 49 67 38 / 40 20 10 0
CARTERSVILLE 75 53 72 41 / 40 20 5 0
COLUMBUS 79 59 78 47 / 60 40 10 0
GAINESVILLE 74 54 72 44 / 40 20 5 0
MACON 81 58 80 44 / 60 50 10 0
ROME 75 53 73 40 / 40 20 5 0
PEACHTREE CITY 75 54 74 38 / 50 30 5 0
VIDALIA 85 65 83 50 / 50 50 20 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1045 AM EDT SAT MAY 11 2013
.UPDATE...
COLD FRONT IS CURRENTLY SITUATED FROM THE EASTERN GREAT LAKES
THROUGH THE MIDDLE ATLANTIC TO THE CENTRAL GULF COAST. THE FRONT
WILL CONTINUE TO MOVE EASTWARD THROUGH THE DAY AND THROUGH THE
REMAINDER OF THE CWFA THIS EVENING/OVERNIGHT.
EARLIER ADJUSTMENTS TO THE GRIDS INCLUDED SOME FINE TUNING OF THE
CLOUD COVER...POPS...AND HOURLY TEMPS/DEWPOINTS. MAX TEMPS LOOK
GOOD FOR NOW. MAIN FORECAST PROBLEM OF THE DAY WILL BE POPS.
SIGNIFICANT CLOUD COVER WILL HELP KEEP SURFACE INSTABILITY
MARGINAL UNDERCUTTING SURFACE HEATING. IN ADDITION...CONVECTION
ALONG THE GULF COAST MAY DISRUPT THE MOISTURE FLOW NORTHWARD.
NAM...GFS...ETC DONT HAVE A REALLY GOOD HANDLE OF THE GULF
CONVECTION. HOWEVER...THE LATEST RUN OF THE HRRR SEEMS TO HANDLE
THE CONVECTION REASONABLY. DO THINK SCT STORMS WILL DEVELOP ALONG
THE FRONT LATER IN THE AFTERNOON...MOSTLY SHOWERS WITH A FEW
THUNDERSTORMS. MAY END UP HAVING TO REDUCE POPS IN THE SOUTH TO
CHANCE...IF THEY GULF CONVECTION CONTINUES TO HOLD TOGETHER.
&&
.PREV DISCUSSION... /ISSUED 747 AM EDT SAT MAY 11 2013/
PREV DISCUSSION... /ISSUED 447 AM EDT SAT MAY 11 2013/
SHORT TERM /TODAY THROUGH SUNDAY/...
CURRENT SATELLITE LOOP SHOWS A LARGE MOISTURE PLUME EXTENDING FROM
THE NEW ENGLAND STATES...DOWN THE EASTERN SEABOARD...AND OVER TO THE
TX GULF COAST. THERE IS A NICE AREA OF ENHANCED SHOWERS AND ISOLATED
THUNDERSTORMS ACROSS TN AND AL BUT THIS PRECIPITATION IS NOT
EXPECTED TO MAKE IT INTO GA UNTIL LATER THIS MORNING INTO THIS
AFTERNOON. THE ACTUAL FRONT ASSOCIATED WITH THIS MOISTURE PLUME IS
BACK ACROSS TN NEAR MEMPHIS AND IT IS MOVING SLOWLY EAST. THIS FRONT
IS EXPECTED TO PUSH INTO NW GA BY 18Z TODAY AND MOVE SOUTH AND EAST
THROUGH THE SHORT TERM. IT SHOULD FINALLY PUSH OFF THE GA COAST BY
18Z SUN. AS THIS FRONT MOVES INTO THE AREA IT WILL BRING INCREASED
MOISTURE AND ACT AS A CATALYST FOR SHRA/TSRA DEVELOPMENT TODAY AND
TONIGHT. INSTABILITIES INCREASE TODAY WITH CAPES GETTING INTO THE
1000-1500 J/KG RANGE AND LIS GETTING DOWN INTO THE -1 TO -3 RANGE BY
18Z-00Z. SHEAR IS EXPECTED TO BE VERY WEAK AND LAPSE RATES ARE NOT
THAT IMPRESSIVE EITHER SO NOT EXPECTING ANY SEVERE STORMS TODAY.
ONCE THIS FRONT MOVES EAST OF THE AREA...A MUCH DRIER AIRMASS MOVES
IN WITH DEWPOINTS IN THE UPPER 30S TO LOWER 40S EXPECTED BY 18Z SUN.
01
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
GFS/ECMWF MODEL GUIDANCE ARE IN GOOD AGREEMENT WITH A BROAD UPPER
UPPER LEVEL TROUGH MOVING THROUGH THE EASTERN U.S. THROUGH MON.
SURFACE HIGH PRESSURE WILL BUILD INTO GA WITH GENERALLY CLEAR
SKIES AND VERY DRY AND COOL AIR ALLOWING TEMPERATURES TO PLUNGE
ONCE AGAIN. AT THIS TIME SUN NIGHT MINS SHOULD BE FROM 10-15
DEGREES BELOW NORMAL WHILE MON MAXES WILL BE AROUND 10 DEGREES
BELOW NORMAL. A RAPID WARM-UP IS EXPECTED TUE THROUGH THU AS AN
UPPER LEVEL RIDGE DEVELOPS AND MOVES INTO THE SOUTHEAST U.S. MIN
AND MAX TEMPERATURES DURING THIS PERIOD WILL RETURN TO NEAR OR A
FEW DEGREES ABOVE NORMAL. THE GFS AND ECMWF MODELS BEGIN TO DIFFER
IN THEIR SOLUTIONS FOR THE END OF THE WEEK. THE GFS DEPICTS A MORE
ORGANIZED COLD FRONT MOVING THROUGH THE TN VALLEY THU NIGHT AND
FRI WHILE THE ECMWF HAS A WEAK PRESSURE PATTERN ALOFT. WILL GO
WITH THE GFS FOR NOW INDICATING ISOLATED TO SCATTERED TSTMS WITH
THE DIURNAL HEATING ON THU BECOMING MORE INFLUENCED BY THE
APPROACHING FRONT ON FRIDAY.
16
AVIATION...
12Z UPDATE...
VFR CONDITIONS TO START BUT THINGS WILL CHANGE WITH FRONTAL
SYSTEM MOVING IN THIS AFTERNOON/EVENING. THERE ARE A FEW PLACES
WITH SOME LOW STRATUS BUT THAT SHOULD BURN OFF SHORTLY AFTER
SUNRISE. INCREASED CLOUD COVER EXPECTED TODAY WITH CEILINGS
COMING DOWN THROUGH 18Z. THERE AREA SOME SCT SHOWERS ACROSS NW GA
THIS MORNING BUT KEEPING IT OUT OF THE TAF SITES UNTIL AFTER 18Z.
A DRIER AIRMASS MOVES INTO NW GA BY 00Z SUN SO SHOULD SEE ANY
PRECIP THAT IS STILL LINGERING AROUND THE AREA DISSIPATE BY 06Z.
ONLY KEEPING SHRA/TSRA IN THE TAFS THROUGH 00Z SUN. WINDS WILL
STAY OUT OF THE W TO SW IN THE 5-10KT RANGE. WILL SEE SOME HIGHER
GUST IN AND AROUND TSRA DEVELOPMENT.
//ATL CONFIDENCE...12Z UPDATE...
CONFIDENCE MEDIUM TO HIGH ON ALL ELEMENTS.
01
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 79 56 77 43 / 50 30 5 0
ATLANTA 76 55 73 46 / 60 30 5 0
BLAIRSVILLE 72 49 67 38 / 30 20 10 0
CARTERSVILLE 75 53 72 41 / 40 20 5 0
COLUMBUS 79 59 78 47 / 60 40 10 0
GAINESVILLE 74 54 72 44 / 50 20 5 0
MACON 81 58 80 44 / 60 50 10 0
ROME 75 53 73 40 / 40 20 5 0
PEACHTREE CITY 75 54 74 38 / 60 30 5 0
VIDALIA 85 65 83 50 / 50 50 20 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NLISTEMAA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1240 PM CDT SAT MAY 11 2013
.UPDATE...
ISSUED AT 957 AM CDT SAT MAY 11 2013
UPDATING ZONES TO REFLECT CHANCE OF SPRINKLES ACROSS THE NORTHEAST
TODAY. THOUGH MOISTURE REMAINS LIMITED...SECOND COLD FRONT WITH
COLD AIR ALOFT WILL INCREASE CU FIELD NORTHEAST AND POSSIBLY
PRODUCE A FEW LIGHT SHOWERS ALONG WITH GUSTY WINDS THIS AFTERNOON.
&&
.SHORT TERM.../TODAY/
ISSUED AT 325 AM CDT SAT MAY 11 2013
MAIN CONCERNS TODAY WILL BE SUBTLE PRECIP TRENDS AND WIND. UPPER
LEVEL TROUGH...INCLUDING POTENT ND/MN PV ANOMALY...CONTINUES TO
ADVANCE TOWARD THE GREAT LAKES EARLY THIS MORNING. WIDELY SCATTERED
LIGHT SHOWERS HAVE DEVELOPED AHEAD OF THIS FEATURE INTO IA AND ARE
PRIMARILY THERMODYNAMICALLY FORCED. LATEST RAP ANALYSIS SHOWS NICE
COLD FRONT ALOFT WITH RELATIVELY HIGHER BASED THETA-E ADVECTION AND
FRONTOGENETICAL FORCING. RESULTANT PRECIP IS HIGH BASED...TYPICALLY
7K FT OR HIGHER...AND STRUGGLING TO REACH THE GROUND MUCH.
EXTRAPOLATION SUGGESTS WHAT PRECIP THERE IS WILL ADVANCE SOUTH AND
EAST EXITING SE TOWARD 12Z. PRECIP OVER NRN MN IS NOT EXPECTED TO
AFFECT OUR FORECAST AREA BY AFTERNOON DUE TO TRAJECTORIES AND
INCREASING SUBSIDENCE. SOUNDINGS SHOW SOME POTENTIAL FOR SURFACE
BASED REDEVELOPMENT BUT ADEQUATE MOISTURE IS CERTAINLY QUESTIONABLE.
08Z SURFACE ANALYSIS SHOWS INITIAL WIND SHIFT/TROUGH ALONG
CARROLL-WEBSTER CITY-MASON CITY LINE WITH TRUE COLD FRONT SEEMING TO
LACK BEHIND JUST REACHING IA/MN BORDER. MOS GUIDANCE AND SOUNDINGS
SUGGEST WIND WILL INCREASE WITH MIXING TODAY...APPROACHING SUSTAINED
ADVISORY CRITERIA /26 KTS/ NORTHEAST. SOUNDINGS DEPICT MIXING TO
2KM OR MORE BY AFTERNOON WITH MIXED LAYER WINDS SUGGESTING GUSTS
INTO THE LOW 30S /KTS/ NE THIRD.
MAX TEMPS ARE GENERALLY AT OR BELOW MOS GUIDANCE EVEN WITH THIS DEEP
MIXING. THESE SOUNDINGS STRUGGLE TO REACH MOS...LIKELY DUE TO
INFLUENCE OF CLIMO. DEWPOINTS WILL ALSO BE QUITE LOW...DROPPING INTO
THE 20S DUE TO UPSTREAM AIRMASS AND MIXING. MODEL SKIN DEWPOINTS
SEEM TOO HIGH...LIKELY OVERDONE DUE TO EVAPOTRANSPIRATION BEING
BEHIND SCHEDULE.
.LONG TERM.../TONIGHT THROUGH FRIDAY/
ISSUED AT 325 AM CDT SAT MAY 11 2013
A SOMEWHAT HIGH AMPLITUDE UPPER AIR PATTERN INITIALLY GIVES WAY TO
A MORE ZONAL...OR AT LEAST A LOWER AMPLITUDE UPPER PATTERN BY
THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE OVER THE PACIFIC NORTHWEST
BUILDS INTO THE NORTHERN PLAINS BY TUESDAY. AS IT RIDGE MOVES
EAST...IT IS FLATTENED BY A SHORTWAVE MOVING OVER THE RIDGE ACROSS
SOUTHERN CANADA. MEANWHILE...AN OLD UPPER LOW INITIALLY OVER
NORTHWEST MEXICO EJECTS INTO THE CENTRAL PLAINS AND GETS ABSORBED
INTO THE WESTERLIES. THE SHORT RANGE MODELS ARE IN FAIR AGREEMENT
WITH THE EVALUATION OF THE PATTERN THROUGH TUESDAY. AFTER
TUESDAY...THE 00Z GFS/ECMWF START TO DIVERGE WITH THE DETAILS OF
THE UPPER PATTERN AND ASSOCIATED SURFACE REFLECTION. THE 00Z GFS
HAS MORE AMPLITUDE ALLOWING THE SURFACE FRONT TO MOVE SOUTH OF
IOWA BY MIDWEEK. THE ECMWF HAVING A FLATTER LOOKING PATTERN NEVER
PUSHES THE BOUNDARY THROUGH THE STATE BEFORE LIFTING IT BACK NORTH
LATE IN THE WEEK.
THE SHORT RANGE MODELS ARE IN GOOD AGREEMENT CONCERNING THE
POSITION OF THE POLAR SURFACE HIGH OVER THE MISSOURI VALLEY BY 12Z
SUNDAY. IT WOULD APPEAR THAT A GOOD RADIATION COOLING SCENARIO
SHOULD OCCUR OVER WESTERN IOWA SUNDAY MORNING. WITH LIGHT WINDS
AND LOWS APPROACHING FREEZING...WILL ISSUE A FROST ADVISORY FOR
PART OF WESTERN AND NORTHERN SECTIONS OF THE FORECAST AREA. SOME
CONCERN ABOUT LOW DEWPOINTS...BUT WHERE THE WIND IS VERY
LIGHT...THERE SHOULD BE ENOUGH FROST FORMATION TO WARRANT
ADVISORY.
NEXT UP WILL BE THE RAPID WARM UP EARLY NEXT WEEK AS BEFORE MENTION
UPPER RIDGE MOVES ACROSS THE NORTHERN CONUS. MODELS ARE IN GOOD
AGREEMENT WITH VERY WARM 850 MB TEMPERATURES ON TUESDAY IN THE
WARM SECTOR AHEAD OF THE APPROACHING COLD FRONT. BASICALLY USED THE
PREVIOUS FORECAST FOR HIGHS WHICH LOOK ON TARGET.
THE PATTERN LOOKS MORE ACTIVE CONCERNING THUNDERSTORMS FROM THE
MIDDLE OF NEXT WEEK THROUGH THE END OF THE FORECAST PERIOD. THERE
SHOULD BE AN WEST TO EAST BOUNDARY IN THE AREA WHICH CLIMATOLOGICALLY
SUPPORTS THUNDERSTORM CHANCES.
&&
.AVIATION...11/18Z
ISSUED AT 1236 PM CDT SAT MAY 11 2013
WINDS CONTINUE TO BE THE MAIN CONCERN THIS AFTERNOON WTIH GUSTS
EXCEEDING 35 KTS ACROSS THE AREA FOR THE NEXT SEVERAL HOURS. CIGS
WILL REMAIN VFR BUT EXPECT HIGHER GUSTS AT TIMES NEAR CU FIELD. AS
HIGH BUILDS INTO THE REGION TONIGHT WINDS WILL RELAX AND DROP OFF
SIGNIFICANTLY AFT 01Z MOST AREAS. SOME INCREASE AGAIN IN WINDS AFT
15-16Z SUNDAY WITH MIXING AND A FEW CUMULUS OVER THE NORTHEAST AT
THAT TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR AUDUBON-CALHOUN-
CARROLL-CASS-CERRO GORDO-CRAWFORD-EMMET-GREENE-GUTHRIE-HANCOCK-
HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT.
&&
$$
UPDATE...REV
SHORT TERM...SMALL
LONG TERM...JOHNSON
AVIATION...REV
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1006 AM CDT SAT MAY 11 2013
.UPDATE...
ISSUED AT 957 AM CDT SAT MAY 11 2013
UPDATING ZONES TO REFLECT CHANCE OF SPRINKLES ACROSS THE NORTHEAST
TODAY. THOUGH MOISTURE REMAINS LIMITED...SECOND COLD FRONT WITH
COLD AIR ALOFT WILL INCREASE CU FIELD NORTHEAST AND POSSIBLY
PRODUCE A FEW LIGHT SHOWERS ALONG WITH GUSTY WINDS THIS AFTERNOON.
&&
.SHORT TERM.../TODAY/
ISSUED AT 325 AM CDT SAT MAY 11 2013
MAIN CONCERNS TODAY WILL BE SUBTLE PRECIP TRENDS AND WIND. UPPER
LEVEL TROUGH...INCLUDING POTENT ND/MN PV ANOMALY...CONTINUES TO
ADVANCE TOWARD THE GREAT LAKES EARLY THIS MORNING. WIDELY SCATTERED
LIGHT SHOWERS HAVE DEVELOPED AHEAD OF THIS FEATURE INTO IA AND ARE
PRIMARILY THERMODYNAMICALLY FORCED. LATEST RAP ANALYSIS SHOWS NICE
COLD FRONT ALOFT WITH RELATIVELY HIGHER BASED THETA-E ADVECTION AND
FRONTOGENETICAL FORCING. RESULTANT PRECIP IS HIGH BASED...TYPICALLY
7K FT OR HIGHER...AND STRUGGLING TO REACH THE GROUND MUCH.
EXTRAPOLATION SUGGESTS WHAT PRECIP THERE IS WILL ADVANCE SOUTH AND
EAST EXITING SE TOWARD 12Z. PRECIP OVER NRN MN IS NOT EXPECTED TO
AFFECT OUR FORECAST AREA BY AFTERNOON DUE TO TRAJECTORIES AND
INCREASING SUBSIDENCE. SOUNDINGS SHOW SOME POTENTIAL FOR SURFACE
BASED REDEVELOPMENT BUT ADEQUATE MOISTURE IS CERTAINLY QUESTIONABLE.
08Z SURFACE ANALYSIS SHOWS INITIAL WIND SHIFT/TROUGH ALONG
CARROLL-WEBSTER CITY-MASON CITY LINE WITH TRUE COLD FRONT SEEMING TO
LACK BEHIND JUST REACHING IA/MN BORDER. MOS GUIDANCE AND SOUNDINGS
SUGGEST WIND WILL INCREASE WITH MIXING TODAY...APPROACHING SUSTAINED
ADVISORY CRITERIA /26 KTS/ NORTHEAST. SOUNDINGS DEPICT MIXING TO
2KM OR MORE BY AFTERNOON WITH MIXED LAYER WINDS SUGGESTING GUSTS
INTO THE LOW 30S /KTS/ NE THIRD.
MAX TEMPS ARE GENERALLY AT OR BELOW MOS GUIDANCE EVEN WITH THIS DEEP
MIXING. THESE SOUNDINGS STRUGGLE TO REACH MOS...LIKELY DUE TO
INFLUENCE OF CLIMO. DEWPOINTS WILL ALSO BE QUITE LOW...DROPPING INTO
THE 20S DUE TO UPSTREAM AIRMASS AND MIXING. MODEL SKIN DEWPOINTS
SEEM TOO HIGH...LIKELY OVERDONE DUE TO EVAPOTRANSPIRATION BEING
BEHIND SCHEDULE.
.LONG TERM.../TONIGHT THROUGH FRIDAY/
ISSUED AT 325 AM CDT SAT MAY 11 2013
A SOMEWHAT HIGH AMPLITUDE UPPER AIR PATTERN INITIALLY GIVES WAY TO
A MORE ZONAL...OR AT LEAST A LOWER AMPLITUDE UPPER PATTERN BY
THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE OVER THE PACIFIC NORTHWEST
BUILDS INTO THE NORTHERN PLAINS BY TUESDAY. AS IT RIDGE MOVES
EAST...IT IS FLATTENED BY A SHORTWAVE MOVING OVER THE RIDGE ACROSS
SOUTHERN CANADA. MEANWHILE...AN OLD UPPER LOW INITIALLY OVER
NORTHWEST MEXICO EJECTS INTO THE CENTRAL PLAINS AND GETS ABSORBED
INTO THE WESTERLIES. THE SHORT RANGE MODELS ARE IN FAIR AGREEMENT
WITH THE EVALUATION OF THE PATTERN THROUGH TUESDAY. AFTER
TUESDAY...THE 00Z GFS/ECMWF START TO DIVERGE WITH THE DETAILS OF
THE UPPER PATTERN AND ASSOCIATED SURFACE REFLECTION. THE 00Z GFS
HAS MORE AMPLITUDE ALLOWING THE SURFACE FRONT TO MOVE SOUTH OF
IOWA BY MIDWEEK. THE ECMWF HAVING A FLATTER LOOKING PATTERN NEVER
PUSHES THE BOUNDARY THROUGH THE STATE BEFORE LIFTING IT BACK NORTH
LATE IN THE WEEK.
THE SHORT RANGE MODELS ARE IN GOOD AGREEMENT CONCERNING THE
POSITION OF THE POLAR SURFACE HIGH OVER THE MISSOURI VALLEY BY 12Z
SUNDAY. IT WOULD APPEAR THAT A GOOD RADIATION COOLING SCENARIO
SHOULD OCCUR OVER WESTERN IOWA SUNDAY MORNING. WITH LIGHT WINDS
AND LOWS APPROACHING FREEZING...WILL ISSUE A FROST ADVISORY FOR
PART OF WESTERN AND NORTHERN SECTIONS OF THE FORECAST AREA. SOME
CONCERN ABOUT LOW DEWPOINTS...BUT WHERE THE WIND IS VERY
LIGHT...THERE SHOULD BE ENOUGH FROST FORMATION TO WARRANT
ADVISORY.
NEXT UP WILL BE THE RAPID WARM UP EARLY NEXT WEEK AS BEFORE MENTION
UPPER RIDGE MOVES ACROSS THE NORTHERN CONUS. MODELS ARE IN GOOD
AGREEMENT WITH VERY WARM 850 MB TEMPERATURES ON TUESDAY IN THE
WARM SECTOR AHEAD OF THE APPROACHING COLD FRONT. BASICALLY USED THE
PREVIOUS FORECAST FOR HIGHS WHICH LOOK ON TARGET.
THE PATTERN LOOKS MORE ACTIVE CONCERNING THUNDERSTORMS FROM THE
MIDDLE OF NEXT WEEK THROUGH THE END OF THE FORECAST PERIOD. THERE
SHOULD BE AN WEST TO EAST BOUNDARY IN THE AREA WHICH CLIMATOLOGICALLY
SUPPORTS THUNDERSTORM CHANCES.
&&
.AVIATION...11/12Z
ISSUED AT 654 AM CDT SAT MAY 11 2013
VFR CONDITIONS ARE ANTICIPATED THROUGHOUT THE PERIOD. 12Z SURFACE
ANALYSIS SHOWS WIND SHIFT/PRESSURE TROUGH JUST EXITING SERN IA
WITH ACTUAL COLD FRONT FOLLOWING CLOSE BEHIND. GUSTY NW WINDS ARE
ANTICIPATED BEHIND THE FRONT TODAY WITH GUSTS OVER 30 KTS AT
TIMES. MID CLOUDS WILL EXIT SRN IA THIS MORNING FOLLOWED BY SCT-
BKN VFR CLOUDS DURING PEAK HEATING. OTHERWISE CLEAR SKIES ARE EXPECTED.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR AUDUBON-CALHOUN-
CARROLL-CASS-CERRO GORDO-CRAWFORD-EMMET-GREENE-GUTHRIE-HANCOCK-
HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT.
&&
$$
UPDATE...REV
SHORT TERM...SMALL
LONG TERM...JOHNSON
AVIATION...SMALL
AREA FORECAST DISCUSSION
NWS DES MOINES IA
655 AM CDT SAT MAY 11 2013
.SHORT TERM.../TODAY/
ISSUED AT 325 AM CDT SAT MAY 11 2013
MAIN CONCERNS TODAY WILL BE SUBTLE PRECIP TRENDS AND WIND. UPPER
LEVEL TROUGH...INCLUDING POTENT ND/MN PV ANOMALY...CONTINUES TO
ADVANCE TOWARD THE GREAT LAKES EARLY THIS MORNING. WIDELY SCATTERED
LIGHT SHOWERS HAVE DEVELOPED AHEAD OF THIS FEATURE INTO IA AND ARE
PRIMARILY THERMODYNAMICALLY FORCED. LATEST RAP ANALYSIS SHOWS NICE
COLD FRONT ALOFT WITH RELATIVELY HIGHER BASED THETA-E ADVECTION AND
FRONTOGENETICAL FORCING. RESULTANT PRECIP IS HIGH BASED...TYPICALLY
7K FT OR HIGHER...AND STRUGGLING TO REACH THE GROUND MUCH.
EXTRAPOLATION SUGGESTS WHAT PRECIP THERE IS WILL ADVANCE SOUTH AND
EAST EXITING SE TOWARD 12Z. PRECIP OVER NRN MN IS NOT EXPECTED TO
AFFECT OUR FORECAST AREA BY AFTERNOON DUE TO TRAJECTORIES AND
INCREASING SUBSIDENCE. SOUNDINGS SHOW SOME POTENTIAL FOR SURFACE
BASED REDEVELOPMENT BUT ADEQUATE MOISTURE IS CERTAINLY QUESTIONABLE.
08Z SURFACE ANALYSIS SHOWS INITIAL WIND SHIFT/TROUGH ALONG
CARROLL-WEBSTER CITY-MASON CITY LINE WITH TRUE COLD FRONT SEEMING TO
LACK BEHIND JUST REACHING IA/MN BORDER. MOS GUIDANCE AND SOUNDINGS
SUGGEST WIND WILL INCREASE WITH MIXING TODAY...APPROACHING SUSTAINED
ADVISORY CRITERIA /26 KTS/ NORTHEAST. SOUNDINGS DEPICT MIXING TO
2KM OR MORE BY AFTERNOON WITH MIXED LAYER WINDS SUGGESTING GUSTS
INTO THE LOW 30S /KTS/ NE THIRD.
MAX TEMPS ARE GENERALLY AT OR BELOW MOS GUIDANCE EVEN WITH THIS DEEP
MIXING. THESE SOUNDINGS STRUGGLE TO REACH MOS...LIKELY DUE TO
INFLUENCE OF CLIMO. DEWPOINTS WILL ALSO BE QUITE LOW...DROPPING INTO
THE 20S DUE TO UPSTREAM AIRMASS AND MIXING. MODEL SKIN DEWPOINTS
SEEM TOO HIGH...LIKELY OVERDONE DUE TO EVAPOTRANSPIRATION BEING
BEHIND SCHEDULE.
.LONG TERM.../TONIGHT THROUGH FRIDAY/
ISSUED AT 325 AM CDT SAT MAY 11 2013
A SOMEWHAT HIGH AMPLITUDE UPPER AIR PATTERN INITIALLY GIVES WAY TO
A MORE ZONAL...OR AT LEAST A LOWER AMPLITUDE UPPER PATTERN BY
THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE OVER THE PACIFIC NORTHWEST
BUILDS INTO THE NORTHERN PLAINS BY TUESDAY. AS IT RIDGE MOVES
EAST...IT IS FLATTENED BY A SHORTWAVE MOVING OVER THE RIDGE ACROSS
SOUTHERN CANADA. MEANWHILE...AN OLD UPPER LOW INITIALLY OVER
NORTHWEST MEXICO EJECTS INTO THE CENTRAL PLAINS AND GETS ABSORBED
INTO THE WESTERLIES. THE SHORT RANGE MODELS ARE IN FAIR AGREEMENT
WITH THE EVALUATION OF THE PATTERN THROUGH TUESDAY. AFTER
TUESDAY...THE 00Z GFS/ECMWF START TO DIVERGE WITH THE DETAILS OF
THE UPPER PATTERN AND ASSOCIATED SURFACE REFLECTION. THE 00Z GFS
HAS MORE AMPLITUDE ALLOWING THE SURFACE FRONT TO MOVE SOUTH OF
IOWA BY MIDWEEK. THE ECMWF HAVING A FLATTER LOOKING PATTERN NEVER
PUSHES THE BOUNDARY THROUGH THE STATE BEFORE LIFTING IT BACK NORTH
LATE IN THE WEEK.
THE SHORT RANGE MODELS ARE IN GOOD AGREEMENT CONCERNING THE
POSITION OF THE POLAR SURFACE HIGH OVER THE MISSOURI VALLEY BY 12Z
SUNDAY. IT WOULD APPEAR THAT A GOOD RADIATION COOLING SCENARIO
SHOULD OCCUR OVER WESTERN IOWA SUNDAY MORNING. WITH LIGHT WINDS
AND LOWS APPROACHING FREEZING...WILL ISSUE A FROST ADVISORY FOR
PART OF WESTERN AND NORTHERN SECTIONS OF THE FORECAST AREA. SOME
CONCERN ABOUT LOW DEWPOINTS...BUT WHERE THE WIND IS VERY
LIGHT...THERE SHOULD BE ENOUGH FROST FORMATION TO WARRANT
ADVISORY.
NEXT UP WILL BE THE RAPID WARM UP EARLY NEXT WEEK AS BEFORE MENTION
UPPER RIDGE MOVES ACROSS THE NORTHERN CONUS. MODELS ARE IN GOOD
AGREEMENT WITH VERY WARM 850 MB TEMPERATURES ON TUESDAY IN THE
WARM SECTOR AHEAD OF THE APPROACHING COLD FRONT. BASICALLY USED THE
PREVIOUS FORECAST FOR HIGHS WHICH LOOK ON TARGET.
THE PATTERN LOOKS MORE ACTIVE CONCERNING THUNDERSTORMS FROM THE
MIDDLE OF NEXT WEEK THROUGH THE END OF THE FORECAST PERIOD. THERE
SHOULD BE AN WEST TO EAST BOUNDARY IN THE AREA WHICH IS
COSMOLOGICALLY SUPPORTS THUNDERSTORM CHANCES.
&&
.AVIATION...11/12Z
ISSUED AT 654 AM CDT SAT MAY 11 2013
VFR CONDITIONS ARE ANTICIPATED THROUGHOUT THE PERIOD. 12Z SURFACE
ANALYSIS SHOWS WIND SHIFT/PRESSURE TROUGH JUST EXITING SERN IA
WITH ACTUAL COLD FRONT FOLLOWING CLOSE BEHIND. GUSTY NW WINDS ARE
ANTICIPATED BEHIND THE FRONT TODAY WITH GUSTS OVER 30 KTS AT
TIMES. MID CLOUDS WILL EXIT SRN IA THIS MORNING FOLLOWED BY SCT-
BKN VFR CLOUDS DURING PEAK HEATING. OTHERWISE CLEAR SKIES ARE EXPECTED.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY 3 AM TO 9 AM CDT SUNDAY
AUDUBON-CALHOUN-CARROLL-CASS-CERRO GORDO-CRAWFORD-EMMET-GREENE-GUTHRIE-
HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT
&&
$$
SHORT TERM/AVIATION...SMALL
LONG TERM...JOHNSON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
354 AM CDT SAT MAY 11 2013
.SHORT TERM.../TODAY /...
ISSUED AT 325 AM CDT SAT MAY 11 2013
MAIN CONCERNS TODAY WILL BE SUBTLE PRECIP TRENDS AND WIND. UPPER
LEVEL TROUGH...INCLUDING POTENT ND/MN PV ANOMALY...CONTINUES TO
ADVANCE TOWARD THE GREAT LAKES EARLY THIS MORNING. WIDELY SCATTERED
LIGHT SHOWERS HAVE DEVELOPED AHEAD OF THIS FEATURE INTO IA AND ARE
PRIMARILY THERMODYNAMICALLY FORCED. LATEST RAP ANALYSIS SHOWS NICE
COLD FRONT ALOFT WITH RELATIVELY HIGHER BASED THETA-E ADVECTION AND
FRONTOGENETICAL FORCING. RESULTANT PRECIP IS HIGH BASED...TYPICALLY
7K FT OR HIGHER...AND STRUGGLING TO REACH THE GROUND MUCH.
EXTRAPOLATION SUGGESTS WHAT PRECIP THERE IS WILL ADVANCE SOUTH AND
EAST EXITING SE TOWARD 12Z. PRECIP OVER NRN MN IS NOT EXPECTED TO
AFFECT OUR FORECAST AREA BY AFTERNOON DUE TO TRAJECTORIES AND
INCREASING SUBSIDENCE. SOUNDINGS SHOW SOME POTENTIAL FOR SURFACE
BASED REDEVELOPMENT BUT ADEQUATE MOISTURE IS CERTAINLY QUESTIONABLE.
08Z SURFACE ANALYSIS SHOWS INITIAL WIND SHIFT/TROUGH ALONG
CARROLL-WEBSTER CITY-MASON CITY LINE WITH TRUE COLD FRONT SEEMING TO
LACK BEHIND JUST REACHING IA/MN BORDER. MOS GUIDANCE AND SOUNDINGS
SUGGEST WIND WILL INCREASE WITH MIXING TODAY...APPROACHING SUSTAINED
ADVISORY CRITERIA /26 KTS/ NORTHEAST. SOUNDINGS DEPICT MIXING TO
2KM OR MORE BY AFTERNOON WITH MIXED LAYER WINDS SUGGESTING GUSTS
INTO THE LOW 30S /KTS/ NE THIRD.
MAX TEMPS ARE GENERALLY AT OR BELOW MOS GUIDANCE EVEN WITH THIS DEEP
MIXING. THESE SOUNDINGS STRUGGLE TO REACH MOS...LIKELY DUE TO
INFLUENCE OF CLIMO. DEWPOINTS WILL ALSO BE QUITE LOW...DROPPING INTO
THE 20S DUE TO UPSTREAM AIRMASS AND MIXING. MODEL SKIN DEWPOINTS
SEEM TOO HIGH...LIKELY OVERDONE DUE TO EVAPOTRANSPIRATION BEING
BEHIND SCHEDULE.
.LONG TERM.../TONIGHT THROUGH FRIDAY/...
ISSUED AT 325 AM CDT SAT MAY 11 2013
A SOMEWHAT HIGH AMPLITUDE UPPER AIR PATTERN INITIALLY GIVES WAY TO
A MORE ZONAL...OR AT LEAST A LOWER AMPLITUDE UPPER PATTERN BY
THE MIDDLE OF NEXT WEEK. AN UPPER RIDGE OVER THE PACIFIC NORTHWEST
BUILDS INTO THE NORTHERN PLAINS BY TUESDAY. AS IT RIDGE MOVES
EAST...IT IS FLATTENED BY A SHORTWAVE MOVING OVER THE RIDGE ACROSS
SOUTHERN CANADA. MEANWHILE...AN OLD UPPER LOW INITIALLY OVER
NORTHWEST MEXICO EJECTS INTO THE CENTRAL PLAINS AND GETS ABSORBED
INTO THE WESTERLIES. THE SHORT RANGE MODELS ARE IN FAIR AGREEMENT
WITH THE EVALUATION OF THE PATTERN THROUGH TUESDAY. AFTER
TUESDAY...THE 00Z GFS/ECMWF START TO DIVERGE WITH THE DETAILS OF
THE UPPER PATTERN AND ASSOCIATED SURFACE REFLECTION. THE 00Z GFS
HAS MORE AMPLITUDE ALLOWING THE SURFACE FRONT TO MOVE SOUTH OF
IOWA BY MIDWEEK. THE ECMWF HAVING A FLATTER LOOKING PATTERN NEVER
PUSHES THE BOUNDARY THROUGH THE STATE BEFORE LIFTING IT BACK NORTH
LATE IN THE WEEK.
THE SHORT RANGE MODELS ARE IN GOOD AGREEMENT CONCERNING THE
POSITION OF THE POLAR SURFACE HIGH OVER THE MISSOURI VALLEY BY 12Z
SUNDAY. IT WOULD APPEAR THAT A GOOD RADIATION COOLING SCENARIO
SHOULD OCCUR OVER WESTERN IOWA SUNDAY MORNING. WITH LIGHT WINDS
AND LOWS APPROACHING FREEZING...WILL ISSUE A FROST ADVISORY FOR
PART OF WESTERN AND NORTHERN SECTIONS OF THE FORECAST AREA. SOME
CONCERN ABOUT LOW DEWPOINTS...BUT WHERE THE WIND IS VERY
LIGHT...THERE SHOULD BE ENOUGH FROST FORMATION TO WARRANT
ADVISORY.
NEXT UP WILL BE THE RAPID WARM UP EARLY NEXT WEEK AS BEFORE MENTION
UPPER RIDGE MOVES ACROSS THE NORTHERN CONUS. MODELS ARE IN GOOD
AGREEMENT WITH VERY WARM 850 MB TEMPERATURES ON TUESDAY IN THE
WARM SECTOR AHEAD OF THE APPROACHING COLD FRONT. BASICALLY USED THE
PREVIOUS FORECAST FOR HIGHS WHICH LOOK ON TARGET.
THE PATTERN LOOKS MORE ACTIVE CONCERNING THUNDERSTORMS FROM THE
MIDDLE OF NEXT WEEK THROUGH THE END OF THE FORECAST PERIOD. THERE
SHOULD BE AN WEST TO EAST BOUNDARY IN THE AREA WHICH IS
COSMOLOGICALLY SUPPORTS THUNDERSTORM CHANCES.
&&
.AVIATION...11/06Z
ISSUED AT 1155 PM CDT FRI MAY 10 2013
CDFNT NEAR A KMSP-KGRI LINE WILL PUSH SOUTHEAST NEAR 40 KTS ACROSS
THE STATE TONIGHT. ISOLATED SHOWERS WILL ACCOMPANY THE FRONT WITH
GUSTY NWLY WINDS BEHIND THE FRONT. CONDITIONS WILL REMAIN VFR
THROUGH THE TAF PERIOD. HIGH PRESSURE BUILDING INTO THE STATE SAT
NIGHT WILL CAUSE WINDS TO DROP OFF QUICKLY AT SUNSET.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR AUDUBON-CALHOUN-
CARROLL-CASS-CERRO GORDO-CRAWFORD-EMMET-GREENE-GUTHRIE-HANCOCK-
HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT.
&&
$$
SHORT TERM...SMALL
LONG TERM...JOHNSON
AVIATION...MS MAY 13
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1132 AM MDT SAT MAY 11 2013
.UPDATE...
ISSUED AT 947 AM MDT SAT MAY 11 2013
JUST COMPLETED A MINOR UPDATE...MAINLY FOR TEMPERATURES. CURRENT
TEMPERATURE TRENDS SUPPORT NEAR TO SLIGHTLY WARMER THAN CURRENT
FORECAST. HRRR AND RUC MATCHING UP WELL WITH REALITY AND SUPPORT
DOING THIS AS WELL. ADJUSTED ACCORDINGLY WITH MOST ADJUSTMENT IN
THE FAR SOUTHERN AND SOUTHWEST LOCATIONS.
ALSO PER CURRENT TRENDS AND NEWEST MODEL DATA THAT IS ROLLING
IN...ADJUSTED SKY COVER AND WINDS NOT ONLY FOR TODAY BUT ALSO INTO
TOMORROW. NEWEST MODEL DATA IS ALSO SUPPORTING CURRENT
PRECIPITATION FORECAST THROUGH TOMORROW AND INITIAL IMPRESSIONS
ARE THAT LITTLE IF ANY CHANGES WILL BE MADE TO THE CURRENT POP/WX
FORECAST.
&&
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 200 AM MDT SAT MAY 11 2013
TODAY-TONIGHT...COLD FRONT CURRENTLY MOVING SOUTH ACROSS THE AREA.
SHOULD SEE SOME GUSTY NORTH TO NORTHEAST WINDS UP TO 25 MPH THIS
MORNING BEFORE SFC HIGH MOVES IN DECREASING WINDS RATHER QUICKLY
THIS AFTERNOON. WINDS BECOME SOUTH/SOUTHWESTERLY TONIGHT. A
WEATHER DISTURBANCE MOVES INTO FAR EASTERN COLORADO LATE THIS
AFTERNOON CONTINUING SOUTH/SOUTHEAST EARLY TONIGHT ACROSS THE FAR
SOUTHWEST AND WESTERN PARTS OF THE AREA. HAVE THUNDERSTORMS
MENTIONED IN THESE AREAS. AFTER MIDNIGHT THERE ARE DISCREPANCIES
IN WHETHER OR NOT ANOTHER WEAK DISTURBANCE MOVES ACROSS THE FAR
EASTERN ZONES...THE GFS HAS IT FURTHER EAST OUT OF THE AREA WHILE
THE NAM HAS IT GRAZING PARTS OF OUR AREA. CONSISTENCY THE PAST FEW
DAYS WOULD FAVOR THE NAM SOLUTION AND AS A RESULT HAVE KEPT SOME
SMALL POPS FOR THE EASTERN 1/3-1/4 OF THE AREA. HIGHS TODAY MID
60S TO AROUND 70. LOWS TONIGHT UPPER 30S NEAR FLAGLER WITH 40S
ELSEWHERE.
SUNDAY-SUNDAY NIGHT...MODELS CONTINUE TO HAVE DISCREPANCIES AS TO
WHETHER OR NOT WEATHER DISTURBANCES MOVE THROUGH THE NORTHWEST
FLOW ALOFT. GFS HAS ONE MOVE THROUGH DURING THE AFTERNOON WHILE
THE NAM DOES NOT. FOR NOW NO CHANGES PLANNED. UPPER RIDGE STARTS
TO MOVE IN DURING THE NIGHT SHUNTING ANY APPRECIABLE MOISTURE AND
CONVECTIVE THREAT EAST OF THE AREA. 850 TEMPERATURES WARM 12-14F
SUPPORTING HIGHS IN THE UPPER 70S TO LOW 80S WHICH IS ALSO
SUPPORTED BY BETTER PERFORMING BIAS CORRECTED GRIDS AND MAV/MET
GUIDANCE. NOT MUCH CHANGE NEEDED FROM PREVIOUS FORECAST. LOWS MID
40S TO LOW 50S.
MONDAY-MONDAY NIGHT...UPPER RIDGE CONTINUES TO SLOWLY MOVE EAST
TOWARD THE AREA. 850 TEMPERATURES WARM ANOTHER 8-13F FROM SUNDAYS
VALUES SUPPORTING HIGHS IN THE UPPER 80S WEST TO MID 90S EAST.
BIAS CORRECTED GRIDS AND MAV/MET GUIDANCE AVG A FEW DEGREES
COOLER. BLENDING THEM TOGETHER PRODUCES HIGHS IN THE MID TO UPPER
80S WEST...LOW TO MID 90S EAST. HAVENT GONE QUITE AS WARM AS 850
TEMPS SUPPORT ACROSS THE EASTERN 1/3 OF THE AREA FOR NOW BUT 96-97
DEGREES VERY POSSIBLE. THIS WOULD BREAK RECORD HIGHS FOR THE DATE
(SEE CLIMO SECTION BELOW). LOWS IN THE 50S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 325 AM MDT SAT MAY 11 2013
MERIDIONAL FLOW BREAKS DOWN AS THE PERSISTENT RIDGE OVER THE WESTERN
UNITED STATES FLATTENS WITH A LOW CENTER MOVING EASTWARD ACROSS
SOUTHERN CANADA. THE COLD FRONT TRAILING BEHIND THAT LOW APPROACHES
THE CENTRAL HIGH PLAINS REGION ON TUESDAY AS A CUTOFF LOW THAT HAS
BEEN OVER NORTHERN MEXICO BEGINS TO LIFT OUT ACROSS THE SOUTHERN
PLAINS ON TUESDAY AND TUESDAY NIGHT. THE FRONT MOVES THROUGH THE
REGION EARLY WEDNESDAY WITH SHOWERS AND THUNDERSTORMS FORMING IN THE
VICINITY OF THE FRONT. THIS WILL BRING SOMEWHAT COOLER TEMPERATURES
TO THE REGION ON WEDNESDAY AND THURSDAY.
ZONAL FLOW BEGINS TO REAMPLIFY INTO A RIDGE OVER THE ROCKIES
THURSDAY AND FRIDAY AS THE NEXT UPPER TROUGH MOVES INTO THE WEST
COAST. TEMPERATURE ARE EXPECTED TO RISE THROUGH THE END OF THE WEEK
AND INTO THE WEEKEND WITH THE POSSIBILITY OF ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS EACH DAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1128 AM MDT SAT MAY 11 2013
VFR CONDITIONS THROUGH THE PERIOD. WINDS WILL BE VARIABLE AND
SHIFTING THROUGH THE PERIOD. AFTER 06Z SHOWERS WILL GET NEAR KMCK.
AT THIS TIME CHOSE TO HANDLE THAT WITH VCSH.
&&
.CLIMATE...
ISSUED AT 200 AM MDT SAT MAY 11 2013
RECORD HIGH TEMPERATURES MONDAY:
HILL CITY....96 (1915)
MCCOOK.......95 (1962)
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...99
LONG TERM...LOCKHART
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
953 AM MDT SAT MAY 11 2013
.UPDATE...
ISSUED AT 947 AM MDT SAT MAY 11 2013
JUST COMPLETED A MINOR UPDATE...MAINLY FOR TEMPERATURES. CURRENT
TEMPERATURE TRENDS SUPPORT NEAR TO SLIGHTLY WARMER THAN CURRENT
FORECAST. HRRR AND RUC MATCHING UP WELL WITH REALITY AND SUPPORT
DOING THIS AS WELL. ADJUSTED ACCORDINGLY WITH MOST ADJUSTMENT IN
THE FAR SOUTHERN AND SOUTHWEST LOCATIONS.
ALSO PER CURRENT TRENDS AND NEWEST MODEL DATA THAT IS ROLLING
IN...ADJUSTED SKY COVER AND WINDS NOT ONLY FOR TODAY BUT ALSO INTO
TOMORROW. NEWEST MODEL DATA IS ALSO SUPPORTING CURRENT
PRECIPITATION FORECAST THROUGH TOMORROW AND INITIAL IMPRESSIONS
ARE THAT LITTLE IF ANY CHANGES WILL BE MADE TO THE CURRENT POP/WX
FORECAST.
&&
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 200 AM MDT SAT MAY 11 2013
TODAY-TONIGHT...COLD FRONT CURRENTLY MOVING SOUTH ACROSS THE AREA.
SHOULD SEE SOME GUSTY NORTH TO NORTHEAST WINDS UP TO 25 MPH THIS
MORNING BEFORE SFC HIGH MOVES IN DECREASING WINDS RATHER QUICKLY
THIS AFTERNOON. WINDS BECOME SOUTH/SOUTHWESTERLY TONIGHT. A
WEATHER DISTURBANCE MOVES INTO FAR EASTERN COLORADO LATE THIS
AFTERNOON CONTINUING SOUTH/SOUTHEAST EARLY TONIGHT ACROSS THE FAR
SOUTHWEST AND WESTERN PARTS OF THE AREA. HAVE THUNDERSTORMS
MENTIONED IN THESE AREAS. AFTER MIDNIGHT THERE ARE DISCREPANCIES
IN WHETHER OR NOT ANOTHER WEAK DISTURBANCE MOVES ACROSS THE FAR
EASTERN ZONES...THE GFS HAS IT FURTHER EAST OUT OF THE AREA WHILE
THE NAM HAS IT GRAZING PARTS OF OUR AREA. CONSISTENCY THE PAST FEW
DAYS WOULD FAVOR THE NAM SOLUTION AND AS A RESULT HAVE KEPT SOME
SMALL POPS FOR THE EASTERN 1/3-1/4 OF THE AREA. HIGHS TODAY MID
60S TO AROUND 70. LOWS TONIGHT UPPER 30S NEAR FLAGLER WITH 40S
ELSEWHERE.
SUNDAY-SUNDAY NIGHT...MODELS CONTINUE TO HAVE DISCREPANCIES AS TO
WHETHER OR NOT WEATHER DISTURBANCES MOVE THROUGH THE NORTHWEST
FLOW ALOFT. GFS HAS ONE MOVE THROUGH DURING THE AFTERNOON WHILE
THE NAM DOES NOT. FOR NOW NO CHANGES PLANNED. UPPER RIDGE STARTS
TO MOVE IN DURING THE NIGHT SHUNTING ANY APPRECIABLE MOISTURE AND
CONVECTIVE THREAT EAST OF THE AREA. 850 TEMPERATURES WARM 12-14F
SUPPORTING HIGHS IN THE UPPER 70S TO LOW 80S WHICH IS ALSO
SUPPORTED BY BETTER PERFORMING BIAS CORRECTED GRIDS AND MAV/MET
GUIDANCE. NOT MUCH CHANGE NEEDED FROM PREVIOUS FORECAST. LOWS MID
40S TO LOW 50S.
MONDAY-MONDAY NIGHT...UPPER RIDGE CONTINUES TO SLOWLY MOVE EAST
TOWARD THE AREA. 850 TEMPERATURES WARM ANOTHER 8-13F FROM SUNDAYS
VALUES SUPPORTING HIGHS IN THE UPPER 80S WEST TO MID 90S EAST.
BIAS CORRECTED GRIDS AND MAV/MET GUIDANCE AVG A FEW DEGREES
COOLER. BLENDING THEM TOGETHER PRODUCES HIGHS IN THE MID TO UPPER
80S WEST...LOW TO MID 90S EAST. HAVENT GONE QUITE AS WARM AS 850
TEMPS SUPPORT ACROSS THE EASTERN 1/3 OF THE AREA FOR NOW BUT 96-97
DEGREES VERY POSSIBLE. THIS WOULD BREAK RECORD HIGHS FOR THE DATE
(SEE CLIMO SECTION BELOW). LOWS IN THE 50S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 325 AM MDT SAT MAY 11 2013
MERIDIONAL FLOW BREAKS DOWN AS THE PERSISTENT RIDGE OVER THE WESTERN
UNITED STATES FLATTENS WITH A LOW CENTER MOVING EASTWARD ACROSS
SOUTHERN CANADA. THE COLD FRONT TRAILING BEHIND THAT LOW APPROACHES
THE CENTRAL HIGH PLAINS REGION ON TUESDAY AS A CUTOFF LOW THAT HAS
BEEN OVER NORTHERN MEXICO BEGINS TO LIFT OUT ACROSS THE SOUTHERN
PLAINS ON TUESDAY AND TUESDAY NIGHT. THE FRONT MOVES THROUGH THE
REGION EARLY WEDNESDAY WITH SHOWERS AND THUNDERSTORMS FORMING IN THE
VICINITY OF THE FRONT. THIS WILL BRING SOMEWHAT COOLER TEMPERATURES
TO THE REGION ON WEDNESDAY AND THURSDAY.
ZONAL FLOW BEGINS TO REAMPLIFY INTO A RIDGE OVER THE ROCKIES
THURSDAY AND FRIDAY AS THE NEXT UPPER TROUGH MOVES INTO THE WEST
COAST. TEMPERATURE ARE EXPECTED TO RISE THROUGH THE END OF THE WEEK
AND INTO THE WEEKEND WITH THE POSSIBILITY OF ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS EACH DAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 200 AM MDT SAT MAY 11 2013
FOR KGLD...VFR EXPECTED THROUGH THE PERIOD. NORTH TO NORTHEAST
WINDS 10-15KTS AND GUSTY AT TAF ISSUANCE WILL BECOME LGT/VAR BY
00Z THEN VEER TO THE SOUTH THEN SOUTHWEST AT SPEEDS AROUND 10KTS
TONIGHT. NO PRECIPITATION EXPECTED AT THE TERMINAL BUT MAY SEE
SOME TCU/CB TO THE WEST/SOUTHWEST LATE THIS AFTERNOON THROUGH
EARLY TONIGHT.
FOR KMCK...VFR EXPECTED THROUGH THE PERIOD. NORTH WINDS AROUND
10KTS AT TAF ISSUANCE WILL DECREASE UNDER 5KTS BY VERY LATE IN THE
AFTERNOON THEN SHIFT TO THE SOUTHEAST AROUND 5KTS TONIGHT. THERE
IS A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS TO BE AROUND THE
TERMINAL AFTER 09Z.
&&
.CLIMATE...
ISSUED AT 200 AM MDT SAT MAY 11 2013
RECORD HIGH TEMPERATURES MONDAY:
HILL CITY....96 (1915)
MCCOOK.......95 (1962)
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...99
LONG TERM...LOCKHART
AVIATION...99
AREA FORECAST DISCUSSION...UPDATED
NWS PADUCAH KY
1144 PM CDT FRI MAY 10 2013
.UPDATE...
ISSUED AT 1139 PM CDT FRI MAY 10 2013
UPDATED THE AVIATION SECTION FOR THE 06Z TAF ISSUANCE.
&&
UPDATE ISSUED AT 809 CDT FRI MAY 10 2013
MAIN ADJUSTMENT EARLY THIS EVENING IS THE TIMING/LOCATION OF THE
CURRENT CONVECTIVE ACTIVITY /SHOWERS AND THUNDERSTORMS/...AS WELL
AS THE ATTENDENT WIND AND TEMPERATURE FIELDS BEHIND THE COLD
FRONT. THE 3KM HRRR GUIDANCE...SPATIALLY ADJUSTED...APPEARS TO BE
HANDLING THE STORM SCALE DEVELOPMENT FAIRLY WELL THROUGH MIDNIGHT.
GIVEN THE POST-FRONTAL CLOUD COVER AND LIMITED EROSION OF THIS
CLOUD COVER DUE TO LOW AMPLITUDE COLD AIR ADVECTION...FOG
POTENTIAL SHOULD REMAIN MINIMAL OVER THE WFO PAH FORECAST AREA.
UPDATE ISSUED AT 637 PM CDT FRI MAY 10 2013
UPDATED THE AVIATION SECTION FOR THE 00Z TAF ISSUANCE.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 258 PM CDT FRI MAY 10 2013
THE COLD FRONT HAS YET TO REALLY PUSH INTO THE FORECAST AREA AS OF
1930Z. A PRE-FRONTAL WIND SHIFT HAS FOCUSED SOME SCATTERED
CONVECTION ON A LINE FROM NEAR KPOF TO KMWA...BUT IT HAS ONLY
GENERATED SPORADIC LIGHTNING. LAPS INDICATES THAT THE MOST
UNSTABLE SURFACE AIRMASS IS OVER FAR SOUTHEAST MISSOURI AND
SOUTHWEST KENTUCKY...SO WOULD EXPECT THAT CONVECTION TO PROGRESS
SOUTHEAST THROUGH 00Z. ANOTHER BAND OF SHOWERS WILL PUSH THROUGH
THE KOWB AREA IN THE NEXT HOUR OR SO.
WILL TAKE THE EASY WAY OUT AND JUST MOVE AN AREA OF LIKELY POPS
SOUTHEAST THROUGH WEST KENTUCKY THROUGH SUNSET...ALTHOUGH WITH THE
VERY SLOW SPEED OF MOVEMENT OF BOUNDARIES AND CONVECTIVE
ELEMENTS...COULD SEE IT FALLING APART BEFORE REACHING THE FAR
SOUTHEAST PORTIONS OF THE FORECAST AREA.
WILL QUICKLY DIMINISH POPS FROM NORTHWEST TO SOUTHEAST THROUGH THE
FIRST PART OF THE EVENING...BUT THE FRONT WILL LAG BEHIND THIS
EVENING...NOT CLEARING THE ENTIRE AREA UNTIL AROUND 06Z.
FOR SATURDAY...THE MODELS HAVE CONTINUED THEIR AGGRESSIVE TREND IN
BRING A BAND OF SHOWERS AND POSSIBLY THUNDERSTORMS THROUGH THE
AREA ALONG A SECONDARY FRONT. THIS FRONT WILL BE QUITE STRONG AND
SHALLOW...SO WOULD EXPECT IT TO MAKE QUICKER PROGRESS THROUGH THE
AREA. HAVE A BAND OF 20-40 POPS MOVING SOUTHWARD THROUGH THE
FORECAST AREA THROUGH THE AFTERNOON. WILL EVEN LINGER A SLIGHT
CHANCE OF SHOWERS OVER WEST KENTUCKY INTO THE EVENING.
GOOD COLD...DRY ADVECTION IS EXPECTED SATURDAY NIGHT AND
SUNDAY. THE SURFACE HIGH WILL SETTLE OVER THE SUNDAY NIGHT...WHICH
WILL RESULT IN EXCELLENT RADIATIONAL COOLING CONDITIONS. THE
MODELS ARE TRENDING COLDER SUNDAY NIGHT...AND THE CONSENSUS TAKES
DEWPOINTS INTO THE LOWER AND MIDDLE 30S. SO.......LOWS IN THE 30S
AND AT LEAST SOME PATCHY FROST SEEM TO BE LIKELY FOR MUCH OF THE
AREA. HAVE LOOKED AT IT FOR 5 DAYS NOW AND THIS IS BY FAR THE
COOLEST THE MODELS HAVE GONE. HAVE LITTLE REASON TO NOT BELIEVE
IT AT THIS POINT.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 258 PM CDT FRI MAY 10 2013
HIGH PRESSURE WILL USHER IN A MUCH COOLER AND DRIER AIR MASS SUNDAY.
WE EXPECT LOWS AROUND 40 BOTH SUNDAY AND MONDAY MORNINGS WITH MONDAY
THE COOLEST...SECOND DAY AFTER FRONTAL PASSAGE IS USUALLY THE
COOLEST AS A RULE OF THUMB. PATCHY FROST CAN NOT BE RULED OUT AT
THIS TIME BUT WITH CURRENT PROJECTIONS WOULD BE VERY LIMITED AND NOT
WIDESPREAD. HOWEVER WILL MONITOR CLOSELY FOR ANY REVISIONS.
SOUTHERLY FLOW RETURNS ON THE BACKSIDE OF THE HIGH NEXT WEEK WHICH
WILL BEGIN A WARMING TREND. MODELS ARE IN GOOD AGREEMENT THE NEXT
STORM SYSTEM WILL DEVELOP OVER SW US AND DRIVE NE ACROSS THE
PLAINS...REACHING THE HEARTLAND LATE IN THE WEEK. THE LAST COUPLE
GFS RUNS TRY TO PHASE THIS A COLD FRONT APPROACHING FROM THE
NORTH...HOWEVER THE ECMWF STALLS THE FRONT TO THE NORTH AND BRINGS
THE LOW IN A LITTLE SLOWER BUT PAINTS QPF OVER THE AREA AS WELL JUST
A LITTLE LATER. FOR NOW PLAN TO LEAN TOWARD THE SLOWER ECMWF AND
HOLD PRECIP OFF UNTIL POSSIBLY THURSDAY AND MAY END UP HOLDING UNTIL
THURSDAY NIGHT AS THAT SYSTEM BECOMES CLOSER WITH TIME. HOWEVER WILL
WAIT AND SEE WHAT THE EXTENDED INIT PRODUCES AND COLLABORATE WITH
SURROUNDING OFFICES FOR THE BEST FIT OR TIME FRAME FOR NEXT WEEKS
STORM SYSTEM.
&&
.AVIATION...
ISSUED AT 1139 PM CDT FRI MAY 10 2013
MVFR CIGS WILL PREVAIL AT ALL SITES THROUGH 15-16Z...THEN VFR
CONDITIONS THROUGH THE END OF THE PERIOD. NORTHERLY WINDS AOB 10
KTS WILL INCREASE TO 12-14 KTS WITH GUSTS UP TO 24 KTS AFT 00Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
AVIATION...JP
PUBLIC...SMITH
AREA FORECAST DISCUSSION
NWS NEW ORLEANS LA
946 AM CDT SAT MAY 11 2013
.UPDATE...
GIVEN RECENT RADAR TRENDS...AND THE LATEST HRRR MODEL GUIDANCE
HAVE DECIDED TO LOWER RAIN CHANCES FOR MOST OF THE AREA TODAY.
EXPECT ONLY SCATTERED LIGHT RAIN SHOWERS AND AN ISOLATED
THUNDERSTORM TO IMPACT AREAS FROM THE INTERSTATE 10 CORRIDOR
NORTHWARD. ALONG THE LOUISIANA COAST...RAIN CHANCES WILL REMAIN
ELEVATED TODAY...WITH MORE NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS ANTICIPATED. GIVEN THE ANTECDENT CONDITIONS IN PLACE
ACROSS THE SOUTHERN HALF OF THE FORECAST AREA...HAVE KEPT THE
FLASH FLOOD WATCH IN PLACE THROUGH TODAY FOR THESE AREAS.
HOWEVER...AREAS IN SOUTHWEST MISSISSIPPI AND NORTH OF INTERSTATE
12 HAVE BEEN REMOVED FROM THE WATCH GIVEN THE REDUCED THREAT FOR
HEAVY RAINFALL TODAY. HAVE ALSO MOVED UP THE EXPIRATION TIMES FOR
THE FLOOD WATCH IN THE REMAINING AREAS TO THIS EVENING AS THE
CONVECTION SHOULD BE WELL REMOVED FROM THE AREA BY THAT TIME. HAVE
ALSO COOLED DAYTIME HIGHS BACK INTO THE MIDDLE 70S DUE TO THE
ANTICIPATED CLOUD COVER AND RAINFALL ACTIVITY. 32
&&
.PREV DISCUSSION... /ISSUED 326 AM CDT SAT MAY 11 2013/
SHORT TERM...SEVERAL MORE ROUNDS OF SHOWERS AND THUNDERSTORMS
REMAIN BEFORE A SLOW MOVING COLD FRONT PUSHES OFFSHORE TONIGHT. AN
UPPER LEVEL TROUGH AXIS HAS A HOLD ON THE REGION. SEVERAL FAST MOVING
PERTURBATIONS MOVE ALONG THE AXIS PROVIDING THE INSTABILITY TO
KICK HEAVY RAIN. IR SATELLITE SHOWS 2 SUCH IMPULSES POISED TO MOVE
THROUGH. THE FIRST IS ASSOCIATED WITH THE RAIN INDICATED ON RADAR
IN SW LA AND THE OTHER FURTHER WEST IN S TX. EXPECT THE FIRST
IMPULSE TO BRING HEAVY RAIN THIS MORNING AND THE 2ND TO BRING
ANOTHER ROUND OF HEAVY RAIN LATER THIS MORNING ON INTO THE
AFTERNOON HOURS.
PREVIOUS SOUNDING MEASURED A PW OF 1.58 WITH VERY LITTLE TEMP DEW
POINT SPREADS THROUGH 35K FEET. GFS AND ECMWF HAVING SOME
DIFFICULTY HANDLING THE SITUATION...SEEMS MESO MODELS INITIALIZING
BETTER PER WSR88D. GFS HAS THE BULK OF THE RAIN FURTHER SOUTH THAN OTHER
MODEL SOLUTIONS. THE RUC SEEMS TO HAVE THE BEST HANDLE ON THIS
EVENT WITH A 850 THETA E RIDGE MOVING FROM NORTH FROM THE COAST.
EXPECT THE CONVECTION AND HEAVY RAIN TO FOLLOW THE THETA E AXIS.
MESO MODELS ALSO SHOW INCREASING UPPER LEVEL DIVERGENT FLOW WITH
SOME DEGREE OF SFC CONVERGENCE. THE THETA E AXIS... IMPULSE
INDUCED LIFT...UPPER LEVEL DIVERGENCE AND LOW LEVEL CONVERGENCE
ALL ADD UP TO THE POTENTIAL OF HEAVY RAIN. FFG VALUES AVERAGE OUT
TO BE AROUND 1.6 TO 2.1 INCHES AN HOUR FOR MOST LOCATIONS. HOWEVER...
SEVERAL LOCATIONS ARE AT PARTICULAR RISK WITH .5 INCHES FOR AN
HOUR AND EVEN .6 INCHES IN A 6 HOUR PERIOD. RAIN ALONG THE COASTAL
LA PARISHES SUCH AS TERREBONNE AND LAFOURCHE WILL CAUSE FLASH
FLOOD ISSUES EXPANDING TO OTHER AREAS TODAY. ROUND ONE WILL BEGIN
AROUND 10Z WITH ROUND TWO NEAR 17Z.
THE COLD FRONT WILL PUSH THROUGH TONIGHT AND WILL BRING COOLER AND
DRIER AIR INTO THE ENTIRE AREA.
LONG TERM...
WE HAVE A CHANCE TO DRY OUT SUNDAY THROUGH MID WEEK. AN UPPER
TROUGH DIGS INTO THE AREA WED NIGHT AND INTO THURSDAY BRINGING
RAIN CHANCES BACK INTO THE FORECAST. SO FAR... THIS SYSTEM DOES
NOT APPEAR TO BE AS MOIST AND PROLONGED AS THE PREVIOUS. LOOKS LIKE
DIURNAL CONVECTION IS POSSIBLE LATE IN THE WEEK.
MARINE...THE PRESSURE GRADIENT HAS WEAKENED SOME AS THE COLD FRONT
DRIFTS EVER CLOSER TO THE REGION. WEAK TO MODERATE ONSHORE FLOW WILL
GENERALLY CONTINUE THROUGH THE DAY BUT THE FRONT WILL FINALLY PUSH
INTO THE GULF OVERNIGHT AND WINDS WILL BECOME NRLY BEHIND IT.
MODERATE OFFSHORE WINDS ARE EXPECTED TOMORROW BUT AS HIGH PRESSURE
PUSHES INTO THE LOWER MS VALLEY THE PRESSURE GRADIENT WILL TIGHTEN
ACROSS THE NCNTRL AND NERN GULF AND THIS COULD LEAD TO STRONG
OFFSHORE WINDS OVERNIGHT SUN BEFORE FINALLY RELAXING MON AS HIGH
PRESSURE FINALLY SITS IN RIGHT OVER THE AREA. LGT WINDS ARE THEN
EXPECTED THROUGH THE MIDDLE OF THE WEEK AS HIGH PRESSURE DOMINATES
THE REGION. /CAB/
AVIATION...ALL SORTS OF AVIATION ISSUES THIS MORNING. MOST
TERMINALS ARE DEALING WITH CIG OR VSBY REDUCTIONS OR BOTH.
TERMINALS ARE RANGING FROM MVFR TO IFR WITH VSBYS GENERALLY B/T 2
AND 5SM AND CIGS FROM AS LOW AS 600 TO 5K FT. UNTIL CONVECTION MOVES
BACK IN NOT EXPECTING CONDITIONS TO CHANGE MUCH BESIDES BOUNCE
BETWEEN IFR AND MVFR...EVEN TEMPORARILY DROPPING TO LIFR AT TIMES.
CONVECTION SHOULD BEGIN TO IMPACT BTR B/T 915 & 945Z WITH EACH
TERMINAL TO THE EAST SEEING CONVECTION IN UNDER AND HOUR OR 2
AFTERWARD. CURRENT TIMING HAS MSY SEEING CONVECTION NEAR
1030-1045Z. OF COURSE CIGS AND VSBYS WILL BE REDUCED SIGNIFICANTLY
WITH THE CONVECTION AND FREQUENT LIGHTNING WILL BE AN ISSUE AGAIN.
WIND GUSTS WILL BE A PROBLEM BUT DO NOT APPEAR TO BE AS MUCH OF AN
ISSUE AS THEY WERE YESTERDAY. CONVECTION SHOULD FINALLY CLR OUT
AFTER 20Z. /CAB/
DECISION SUPPORT...
DSS CODE...YELLOW.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
MONITORING RIVERS
MONITORING CONVECTION FOR SEVERE AND FLASH FLOODING
DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
SIGNIFICANCE
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 74 55 78 49 / 20 20 10 10
BTR 75 57 79 51 / 40 20 10 10
ASD 75 58 78 51 / 40 30 10 10
MSY 75 63 78 57 / 50 30 10 10
GPT 74 59 78 52 / 40 40 10 10
PQL 75 58 78 50 / 40 40 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH UNTIL 7 PM SATURDAY FOR THE FOLLOWING ZONES:
ASCENSION...ASSUMPTION...EAST BATON
ROUGE...IBERVILLE...LIVINGSTON...ORLEANS...SOUTHERN
TANGIPAHOA...ST. CHARLES...ST. JAMES...ST. JOHN THE
BAPTIST...ST. TAMMANY...UPPER JEFFERSON...UPPER
LAFOURCHE...UPPER PLAQUEMINES...UPPER ST. BERNARD...UPPER
TERREBONNE...AND WEST BATON ROUGE.
GM...NONE.
MS...FLASH FLOOD WATCH UNTIL 7 PM SATURDAY FOR THE FOLLOWING ZONES:
HANCOCK...HARRISON...AND JACKSON.
GM...NONE.
&&
$$
32
AREA FORECAST DISCUSSION
NWS NEW ORLEANS LA
326 AM CDT SAT MAY 11 2013
.SHORT TERM...SEVERAL MORE ROUNDS OF SHOWERS AND THUNDERSTORMS
REMAIN BEFORE A SLOW MOVING COLD FRONT PUSHES OFFSHORE TONIGHT. AN
UPPER LEVEL TROUGH AXIS HAS A HOLD ON THE REGION. SEVERAL FAST MOVING
PERTURBATIONS MOVE ALONG THE AXIS PROVIDING THE INSTABILITY TO
KICK HEAVY RAIN. IR SATELLITE SHOWS 2 SUCH IMPULSES POISED TO MOVE
THROUGH. THE FIRST IS ASSOCIATED WITH THE RAIN INDICATED ON RADAR
IN SW LA AND THE OTHER FURTHER WEST IN S TX. EXPECT THE FIRST
IMPULSE TO BRING HEAVY RAIN THIS MORNING AND THE 2ND TO BRING
ANOTHER ROUND OF HEAVY RAIN LATER THIS MORNING ON INTO THE
AFTERNOON HOURS.
PREVIOUS SOUNDING MEASURED A PW OF 1.58 WITH VERY LITTLE TEMP DEW
POINT SPREADS THROUGH 35K FEET. GFS AND ECMWF HAVING SOME
DIFFICULTY HANDLING THE SITUATION...SEEMS MESO MODELS INITIALIZING
BETTER PER WSR88D. GFS HAS THE BULK OF THE RAIN FURTHER SOUTH THAN OTHER
MODEL SOLUTIONS. THE RUC SEEMS TO HAVE THE BEST HANDLE ON THIS
EVENT WITH A 850 THETA E RIDGE MOVING FROM NORTH FROM THE COAST.
EXPECT THE CONVECTION AND HEAVY RAIN TO FOLLOW THE THETA E AXIS.
MESO MODELS ALSO SHOW INCREASING UPPER LEVEL DIVERGENT FLOW WITH
SOME DEGREE OF SFC CONVERGENCE. THE THETA E AXIS... IMPULSE
INDUCED LIFT...UPPER LEVEL DIVERGENCE AND LOW LEVEL CONVERGENCE
ALL ADD UP TO THE POTENTIAL OF HEAVY RAIN. FFG VALUES AVERAGE OUT
TO BE AROUND 1.6 TO 2.1 INCHES AN HOUR FOR MOST LOCATIONS. HOWEVER...
SEVERAL LOCATIONS ARE AT PARTICULAR RISK WITH .5 INCHES FOR AN
HOUR AND EVEN .6 INCHES IN A 6 HOUR PERIOD. RAIN ALONG THE COASTAL
LA PARISHES SUCH AS TERREBONNE AND LAFOURCHE WILL CAUSE FLASH
FLOOD ISSUES EXPANDING TO OTHER AREAS TODAY. ROUND ONE WILL BEGIN
AROUND 10Z WITH ROUND TWO NEAR 17Z.
THE COLD FRONT WILL PUSH THROUGH TONIGHT AND WILL BRING COOLER AND
DRIER AIR INTO THE ENTIRE AREA.
.LONG TERM...
WE HAVE A CHANCE TO DRY OUT SUNDAY THROUGH MID WEEK. AN UPPER
TROUGH DIGS INTO THE AREA WED NIGHT AND INTO THURSDAY BRINGING
RAIN CHANCES BACK INTO THE FORECAST. SO FAR... THIS SYSTEM DOES
NOT APPEAR TO BE AS MOIST AND PROLONGED AS THE PREVIOUS. LOOKS LIKE
DIURNAL CONVECTION IS POSSIBLE LATE IN THE WEEK.
&&
.MARINE...THE PRESSURE GRADIENT HAS WEAKENED SOME AS THE COLD FRONT
DRIFTS EVER CLOSER TO THE REGION. WEAK TO MODERATE ONSHORE FLOW WILL
GENERALLY CONTINUE THROUGH THE DAY BUT THE FRONT WILL FINALLY PUSH
INTO THE GULF OVERNIGHT AND WINDS WILL BECOME NRLY BEHIND IT.
MODERATE OFFSHORE WINDS ARE EXPECTED TOMORROW BUT AS HIGH PRESSURE
PUSHES INTO THE LOWER MS VALLEY THE PRESSURE GRADIENT WILL TIGHTEN
ACROSS THE NCNTRL AND NERN GULF AND THIS COULD LEAD TO STRONG
OFFSHORE WINDS OVERNIGHT SUN BEFORE FINALLY RELAXING MON AS HIGH
PRESSURE FINALLY SITS IN RIGHT OVER THE AREA. LGT WINDS ARE THEN
EXPECTED THROUGH THE MIDDLE OF THE WEEK AS HIGH PRESSURE DOMINATES
THE REGION. /CAB/
&&
.AVIATION...ALL SORTS OF AVIATION ISSUES THIS MORNING. MOST
TERMINALS ARE DEALING WITH CIG OR VSBY REDUCTIONS OR BOTH.
TERMINALS ARE RANGING FROM MVFR TO IFR WITH VSBYS GENERALLY B/T 2
AND 5SM AND CIGS FROM AS LOW AS 600 TO 5K FT. UNTIL CONVECTION MOVES
BACK IN NOT EXPECTING CONDITIONS TO CHANGE MUCH BESIDES BOUNCE
BETWEEN IFR AND MVFR...EVEN TEMPORARILY DROPPING TO LIFR AT TIMES.
CONVECTION SHOULD BEGIN TO IMPACT BTR B/T 915 & 945Z WITH EACH
TERMINAL TO THE EAST SEEING CONVECTION IN UNDER AND HOUR OR 2
AFTERWARD. CURRENT TIMING HAS MSY SEEING CONVECTION NEAR
1030-1045Z. OF COURSE CIGS AND VSBYS WILL BE REDUCED SIGNIFICANTLY
WITH THE CONVECTION AND FREQUENT LIGHTNING WILL BE AN ISSUE AGAIN.
WIND GUSTS WILL BE A PROBLEM BUT DO NOT APPEAR TO BE AS MUCH OF AN
ISSUE AS THEY WERE YESTERDAY. CONVECTION SHOULD FINALLY CLR OUT
AFTER 20Z. /CAB/
&&
.DECISION SUPPORT...
DSS CODE...YELLOW.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
MONITORING RIVERS
MONITORING CONVECTION FOR SEVERE AND FLASH FLOODING
DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
SIGNIFICANCE
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 77 55 78 49 / 80 20 10 10
BTR 79 57 79 51 / 80 20 10 10
ASD 78 58 78 51 / 80 30 10 10
MSY 77 63 78 57 / 80 30 10 10
GPT 77 59 78 52 / 80 40 10 10
PQL 79 58 78 50 / 80 40 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH UNTIL 1 AM SUNDAY FOR THE FOLLOWING ZONES:
ASCENSION...ASSUMPTION...EAST BATON ROUGE...EAST
FELICIANA...IBERVILLE...LIVINGSTON...NORTHERN
TANGIPAHOA...ORLEANS...POINTE COUPEE...SOUTHERN
TANGIPAHOA...ST. CHARLES...ST. HELENA...ST. JAMES...ST.
JOHN THE BAPTIST...ST. TAMMANY...UPPER JEFFERSON...UPPER
LAFOURCHE...UPPER PLAQUEMINES...UPPER ST. BERNARD...UPPER
TERREBONNE...WASHINGTON...WEST BATON ROUGE...AND WEST
FELICIANA.
GM...NONE.
MS...FLASH FLOOD WATCH UNTIL 1 AM SUNDAY FOR THE FOLLOWING ZONES:
AMITE...HANCOCK...HARRISON...JACKSON...PEARL
RIVER...PIKE...WALTHALL...AND WILKINSON.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
639 PM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH LATER TONIGHT AND CROSS THE REGION ON
SUNDAY WITH ADDITIONAL AFTERNOON SHOWERS. COLDER AND DRIER AIR WILL
FOLLOW FOR EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
0630 PM UPDATE: BEEFED UP POPS TO CATEGORICAL REGION WIDE FOR
EARLY THIS EVENING AS ADDITIONAL SHOWERS ARE MOVING IN AT THIS
HOUR. ALSO MADE SOME ADJUSTMENTS TO QPF FOR THIS
EVENING..GENERALLY UPPING AMOUNTS SLIGHTLY ACROSS MOST OF THE
AREA. FINALLY, SOME MINOR CHANGES TO WINDS AND TEMPERATURES FOR
THE EARLY TO MID EVENING PERIOD. NUDGED BOTH TEMPERATURES AND WINDS DOWN
SLIGHTLY BASED ON CURRENT OBSERVATIONS.
PREVIOUS DISCUSSION: MAIN CHALLENGES WILL BE TIMING OF RAIN
TONIGHT INTO SUNDAY AND TEMPERATURES.
FIRST AREA OF RAIN MOVING TO THE E INTO NEW BRUNSWICK WHILE SEND
AREA OF RAIN AND POSSIBLE TSTMS MOVING INTO SWRN AREAS ATTM PER
THE LATEST RADAR. THIS SECOND AREA OF RAIN WILL OVERSPREAD THE CWA
LATER THIS AFTERNOON INTO EARLY TONIGHT. 12Z UA INDICATED A STRONG
40KT JETLET AT 700MBS ACROSS ONTARIO AND WRN NYS. THIS AREA OF
FORCING WAS PICKED UP BY THE GFS AND CANADIAN GEM. THEREFORE, A
BLEND OF THESE 2 MODELS WERE USED INTO EARLY TONIGHT AS THEY SHOW
A SIGNIFICANT AREA OF RAIN MOVING ACROSS THE REGION. ATMOSPHERE
LOOKS LIKE IT STABILIZES AFTER 22Z AND THEREFORE CUT BACK ON THE
MENTION OF TSTMS FOR OUR CWA. THE LATEST RAP FROM THE SPC MESO-
ANALYSIS PAGE INDICATED SOME POSSIBLE TSTMS EDGING INTO GYX/S WRN
ZONES THIS AFTERNOON AND THEN WEAKENING BY 22Z OR SO. A BLEND OF
THE NERFC/GFS AND SREF WAS USED FOR THE QPF WHICH SHOWED AN
ADDITIONAL 0.15-0.30 THROUGH 06Z AND THEN RAIN END AS THE BEST
FORCING EXITS INTO NEW BRUNSWICK. ADDED FOG FOR ALL THE CWA
OVERNIGHT W/THE MOST DENSE FOG FROM MLT REGION ON SOUTH.
TEMPERATURES WILL BE HELD UP TONIGHT AND FOLLOWED A BLEND OF THE
NAM12 AND REGIONAL GEM FOR TONIGHT`S LOWS SHOWING UPPER 40S OUT
WEST TO LOW TO MID 50S EASTERN AND CENTRAL AREAS.
FOR SUNDAY, DRY W/SOME FOG TO START AND THEN ANOTHER BATCH OF
SHOWERS EXPECTED BY MIDDAY DUE TO THE COLD FRONT APCHG FROM THE W.
STAYED W/A GEM/GFS BLEND FOR TIMING OF THE SHOWERS USING THE MID
LEVEL FORCING FOR THE QPF WHICH SHOWED ANOTHER .10-.20, MAINLY
NORTHERN AND CENTRAL AREAS. HELD BACK THE TEMPERATURES FROM PREVIOUS
THINKING AND LEANED W/LOWER 60S NORTH AND MID 60S CENTRAL AND
DOWNEAST AS CAA LOOKS TO TAKE HOLD IN THE AFTERNOON. TSTM
POTENTIAL LOOKS TO BE LESS LIKELY ESPECIALLY ACROSS THE DOWNEAST
AND COAST DUE TO THE ONSHORE FLOW. BEST CHANCES IF ANY WILL BE
ACROSS THE NORTHERN AND WESTERN AREAS DUE TO SOME ELEVATED
INSTABILITY. ATTM, KEPT ISOLATED THUNDER IN THERE FOR CONTINUITY.
MIDNIGHT CREW CAN ASSESS THIS FURTHER TONIGHT.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
THE FIRST PART OF THE PERIOD WILL BEGIN WITH SHOWERS ACROSS THE
NORTHERN AND CENTRAL PARTS OF THE REGION SUNDAY NIGHT. THESE
SHOWERS ARE DUE TO A BOUNDARY THAT WILL MOVE FROM WEST TO EAST.
THE BEST LIFT LOOKS TO BE ACROSS THE NORTH. ONCE THIS FRONTAL
BOUNDARY PUSHES THROUGH THE REGION TEMPERATURES WILL COOL OFF FOR
MONDAY WITH HIGHS IN THE 50S NORTH AND THE UPPER 50S TO LOWER 60S
SOUTH. AS THE UPPER LEVEL TROUGH MOVES EAST THE 12Z GFS IS TRYING
TO CLOSE THE TROUGH TO THE NORTH WHILE THE 12Z NAM/00Z ECMWF
CONTINUE TO DEVELOP THE CLOSED LOW AROUND THE BASE OF THE TROUGH.
RIGHT NOW WILL LEAN WITH THE SURFACE LOW DEVELOPS TRACKING MAINLY
EAST OF THE AREA LATE TUESDAY INTO TUESDAY NIGHT. MAIN AFFECT TO
THE FORECAST FOR THIS PERIOD WILL BE THE INCREASE IN CLOUDS
COVERAGE WITH HIGHEST COVERAGE SEEN ACROSS THE EASTERN AND
SOUTHEASTERN PARTS OF THE REGION.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
BOTH MEDIUM RANGE MODELS ARE IN GENERAL AGREEMENT IN THE TUESDAY
NIGHT THROUGH THROUGH SUNDAY TIME FRAME. THE FORECAST FOR
WEDNESDAY CONTINUES TO BE DRY. MOISTURE INCREASES WEDNESDAY
NIGHT...AHEAD OF THE NEXT SYSTEM EXPECTED TO MOVE THROUGH THE
AREA...BRINGING A CHANCE OF RAIN MAINLY ON THURSDAY. AT THIS POINT
IT APPEARS WE MAY HAVE A BREAK BETWEEN SYSTEMS ON FRIDAY HOWEVER
LATE FRIDAY INTO SATURDAY SHOULD SEE RAIN CHANCES INCREASE ACROSS
THE REGION ONCE AGAIN. SEASONAL TEMPERATURES ARE EXPECTED THROUGH
THE PERIOD WITH SOME DAYS A LITTLE ABOVE NORMAL AND OTHERS WITH
READINGS A LITTLE BELOW.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: IFR INTO SUNDAY MORNING AND THEN CONDITIONS GO TO MVFR
ESPECIALLY NORTHERN TERMINALS.
SHORT TERM: MOST TAF SITES WILL STAY VFR THROUGH THE PERIOD
EXCEPT FOR SUNDAY NIGHT WITH HEAVIER SHOWERS THERE COULD BE
PERIODS OF MVFR OR IFR.
&&
.MARINE...
NEAR TERM: DECIDED TO TRANSITION THE SCA TO HAZARDOUS SEAS INTO
SUNDAY. WAVES ARE CLIMBING TO 6 ATTM W/A SWELL GENERATED. WILL
CARRY THE MENTION OF THE SWELL INTO SUNDAY. WINDS ARE BELOW SCA
AND EXPECTING THEM TO STAY BELOW INTO SUNDAY. FOLLOWED THE
NAM12/GFS40 BLEND FOR THE WINDS AND FOLLOWED CLOSELY W/THE
MIDNIGHT CREW`S WAVE HEIGHTS OF 4-7 FT.
SHORT TERM: SCA CONDITIONS SUBSIDE BY THE SHORT TERM PERIOD.
KEPT CONSISTENCY WITH LAST NIGHTS SHIFT FOR WAVE AND WIND GRIDS.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM EDT SUNDAY
FOR ANZ050>052.
&&
$$
NEAR TERM...FITZSIMMONS/HEWITT
SHORT TERM...JORDAN
LONG TERM...RUNYAN
AVIATION...FITZSIMMONS/HEWITT/JORDAN
MARINE...FITZSIMMONS/HEWITT/JORDAN
AREA FORECAST DISCUSSION
NWS CARIBOU ME
357 PM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH LATER TONIGHT AND CROSS THE REGION ON
SUNDAY WITH ADDITIONAL AFTERNOON. COLDER AND DRIER AIR WILL
FOLLOW FOR EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
MAIN CHALLENGES WILL BE TIMING OF RAIN TONIGHT INTO SUNDAY AND
TEMPERATURES.
FIRST AREA OF RAIN MOVING TO THE E INTO NEW BRUNWICK WHILE SEND
AREA OF RAIN AND POSSIBLE TSTMS MOVING INTO SWRN AREAS ATTM PER
THE LATEST RADAR. THIS SECOND AREA OF RAIN WILL OVERSPREAD THE CWA
LATER THIS AFTERNOON INTO EARLY TONIGHT. 12Z UA INDICATED A STRONG
40KT JETLET AT 700MBS ACROSS ONTARIO AND WRN NYS. THIS AREA OF
FORCING WAS PICKED UP BY THE GFS AND CANADIAN GEM. THEREFORE, A
BLEND OF THESE 2 MODELS WERE USED INTO EARLY TONIGHT AS THEY SHOW
A SIGNIFICANT AREA OF RAIN MOVING ACROSS THE REGION. ATMOSPHERE
LOOKS LIKE IT STABILIZES AFTER 22Z AND THEREFORE CUT BACK ON THE
MENTION OF TSTMS FOR OUR CWA. THE LATEST RAP FROM THE SPC MESO-
ANALYSIS PAGE INDICATED SOME POSSIBLE TSTMS EDGING INTO GYX/S WRN
ZONES THIS AFTERNOON AND THEN WEAKENING BY 22Z OR SO. A BLEND OF
THE NERFC/GFS AND SREF WAS USED FOR THE QPF WHICH SHOWED AN
ADDITIONAL 0.15-0.30 THROUGH 06Z AND THEN RAIN END AS THE BEST
FORCING EXITS INTO NEW BRUNSWICK. ADDED FOG FOR ALL THE CWA
OVERNIGHT W/THE MOST DENSE FOG FROM MLT REGION ON SOUTH.
TEMPERATURES WILL BE HELD UP TONIGHT AND FOLLOWED A BLEND OF THE
NAM12 AND REGIONAL GEM FOR TONIGHT`S LOWS SHOWING UPPER 40S OUT
WEST TO LOW TO MID 50S EASTERN AND CENTRAL AREAS.
FOR SUNDAY, DRY W/SOME FOG TO START AND THEN ANOTHER BATCH OF
SHOWERS EXPECTED BY MIDDAY DUE TO THE COLD FRONT APCHG FROM THE W.
STAYED W/A GEM/GFS BLEND FOR TIMING OF THE SHOWERS USING THE MID
LEVEL FORCING FOR THE QPF WHICH SHOWED ANOTHER .10-.20, MAINLY
NORTHERN AND CENTRAL AREAS. HELD BACK THE TEMPERATURES FROM PREVIOUS
THINKING AND LEANED W/LOWER 60S NORTH AND MID 60S CENTRAL AND
DOWNEAST AS CAA LOOKS TO TAKE HOLD IN THE AFTERNOON. TSTM
POTENTIAL LOOKS TO BE LESS LIKELY ESPECIALLY ACROSS THE DOWNEAST
AND COAST DUE TO THE ONSHORE FLOW. BEST CHANCES IF ANY WILL BE
ACROSS THE NORTHERN AND WESTERN AREAS DUE TO SOME ELEVATED
INSTABILITY. ATTM, KEPT ISOLATED THUNDER IN THERE FOR CONTINUITY.
MIDNIGHT CREW CAN ASSESS THIS FURTHER TONIGHT.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
THE FIRST PART OF THE PERIOD WILL BEGIN WITH SHOWERS ACROSS THE
NORTHERN AND CENTRAL PARTS OF THE REGION SUNDAY NIGHT. THESE
SHOWERS ARE DUE TO A BOUNDARY THAT WILL MOVE FROM WEST TO EAST.
THE BEST LIFT LOOKS TO BE ACROSS THE NORTH. ONCE THIS FRONTAL
BOUNDARY PUSHES THROUGH THE REGION TEMPERATURES WILL COOL OFF FOR
MONDAY WITH HIGHS IN THE 50S NORTH AND THE UPPER 50S TO LOWER 60S
SOUTH. AS THE UPPER LEVEL TROUGH MOVES EAST THE 12Z GFS IS TRYING
TO CLOSE THE TROUGH TO THE NORTH WHILE THE 12Z NAM/00Z ECMWF
CONTINUE TO DEVELOP THE CLOSED LOW AROUND THE BASE OF THE TROUGH.
RIGHT NOW WILL LEAN WITH THE SURFACE LOW DEVELOPS TRACKING MAINLY
EAST OF THE AREA LATE TUESDAY INTO TUESDAY NIGHT. MAIN AFFECT TO
THE FORECAST FOR THIS PERIOD WILL BE THE INCREASE IN CLOUDS
COVERAGE WITH HIGHEST COVERAGE SEEN ACROSS THE EASTERN AND
SOUTHEASTERN PARTS OF THE REGION.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
BOTH MEDIUM RANGE MODELS ARE IN GENERAL AGREEMENT IN THE TUESDAY
NIGHT THROUGH THROUGH SUNDAY TIME FRAME. THE FORECAST FOR
WEDNESDAY CONTINUES TO BE DRY. MOISTURE INCREASES WEDNESDAY
NIGHT...AHEAD OF THE NEXT SYSTEM EXPECTED TO MOVE THROUGH THE
AREA...BRINGING A CHANCE OF RAIN MAINLY ON THURSDAY. AT THIS POINT
IT APPEARS WE MAY HAVE A BREAK BETWEEN SYSTEMS ON FRIDAY HOWEVER
LATE FRIDAY INTO SATURDAY SHOULD SEE RAIN CHANCES INCREASE ACROSS
THE REGION ONCE AGAIN. SEASONAL TEMPERATURES ARE EXPECTED THROUGH
THE PERIOD WITH SOME DAYS A LITTLE ABOVE NORMAL AND OTHERS WITH
READINGS A LITTLE BELOW.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
NEAR TERM: IFR INTO SUNDAY MORNING AND THEN CONDITIONS GO TO MVFR
ESPECIALLY NORTHERN TERMINALS.
SHORT TERM: MOST TAF SITES WILL STAY VFR THROUGH THE PERIOD
EXCEPT FOR SUNDAY NIGHT WITH HEAVIER SHOWERS THERE COULD BE
PERIODS OF MVFR OR IFR.
&&
.MARINE...
NEAR TERM: DECIDED TO TRANSITION THE SCA TO HAZARDOUS SEAS INTO
SUNDAY. WAVES ARE CLIMBING TO 6 ATTM W/A SWELL GENERATED. WILL
CARRY THE MENTION OF THE SWELL INTO SUNDAY. WINDS ARE BELOW SCA
AND EXPECTING THEM TO STAY BELOW INTO SUNDAY. FOLLOWED THE
NAM12/GFS40 BLEND FOR THE WINDS AND FOLLOWED CLOSELY W/THE
MIDNIGHT CREW`S WAVE HEIGHTS OF 4-7 FT.
SHORT TERM: SCA CONDITIONS SUBSIDE BY THE SHORT TERM PERIOD.
KEPT CONSISTENCY WITH LAST NIGHTS SHIFT FOR WAVE AND WIND GRIDS.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM EDT
SUNDAY FOR ANZ050>052.
&&
$$
NEAR TERM...HEWITT
SHORT TERM...JORDAN
LONG TERM...RUNYAN
AVIATION...HEWITT/JORDAN
MARINE...HEWITT/JORDAN
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
500 PM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT CROSSES THE MID ATLANTIC TONIGHT FOLLOWED BY A
SECONDARY COLD FRONT SUNDAY EVENING. CANADIAN HIGH PRESSURE BUILDS
INTO THE REGION MONDAY AND MONDAY NIGHT BRINGING A VERY COOL
AIR FOR THE MIDDLE OF MAY...BEFORE SLIDING OFF THE COAST TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE LATEST REGIONAL RADAR MOSAIC SHOWS ISOLATED TO SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE REGION MARGINALLY UNSTABLE AIRMASS
(~1000 J/KG OF MLCAPE) ALONG WITH MODEST DEEP LAYER SHEAR (30-40KT
0-6KM). CURRENT GOES WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH
LIFTING NE ACROSS PA ALONG WITH STRONGER SYNOPTIC SCALE
DYNAMICS...HENCE ANY STORMS ACROSS THE LOCAL AREA HAVE STRUGGLED TO
ORGANIZE AND PERSIST. THIS TREND IS EXPECTED TO CONTINUE OVER THE
NEXT FEW HOURS BEFORE A JET STREAK OVER THE TENNESSEE VALLEY EJECTS
NE ACROSS THE REGION AHEAD OF A FRONTAL ZONE APPROACHING FROM THE
WEST.
THE LATEST RUC BRINGS THE JET ACROSS THE AREA DURING THE MID-EVENING
THROUGH EARLY OVERNIGHT HOURS. GIVEN THIS...A BAND OF LIKELY POPS
WILL BE FORECAST TO MOVE W-E OVER THE CWA. HOWEVER...QPF AMOUNTS
SHOULD BE RATHER MINIMAL. THUNDER WILL BE MAINTAINED THROUGH
MIDNIGHT TO ACCOUNT FOR ANY LINGERING INSTABILITY BEFORE
TRANSITIONING TO ONLY SHOWERS AFTER MIDNIGHT. LOW TEMPERATURES SHOULD
RANGE FROM THE LOW 50S NW...TO LOW 60S SE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
STEADY CAA COMMENCES SUNDAY AS THE COLD FRONT MOVES OFF THE COAST
SUNDAY MORNING AND HIGH PRESSURE BUILDS OVER THE MISSISSIPPI VALLEY.
THIS SHOULD PRODUCE A RATHER PLEASANT DAY WITH LOW-LEVEL THICKNESS
VALUES SUPPORTING HIGHS IN THE UPPER 60S N/NW...TO THE LOW/MID 70S
SE UNDER AN INCREASINGLY SUNNY SKY.
A SECONDARY COLD FRONT SWINGS THROUGH THE REGION SUNDAY NIGHT. THE
CONTINUATION OF STEADY CAA OVERNIGHT WILL DRIVE LOW TEMPERATURES
DOWN INTO THE UPPER 30S N/NW TO THE MID/UPPER 40S FAR SE UNDER A
CLEAR SKY. THERE SHOULD BE ENOUGH MIXING ALONG WITH DRY AIR/LOW
DEWPOINTS TO INHIBIT ANY FROST DEVELOPMENT IN THE COLDER SPOTS.
VERY COLD AIR ALOFT FOR MID-MAY ARRIVES MONDAY DRIVING 1000-500MB
THICKNESS VALUES DOWN TO AROUND 532-540DAM. A STRONG VORT MAX/PV MIN
DIVES AROUND THE BACK-SIDE OF THE PARENT TROUGH DURING THE
AFTERNOON. THIS ENERGY DROPPING INTO THE TROUGH WILL DROP 500MB
HEIGHTS TO -2 TO -3 ST DEV PER 11/12Z GEFS MEAN AT 00Z TUESDAY.
GIVEN THIS...A BKN SC DECK IS EXPECTED TO DEVELOP DURING THE
AFTERNOON. LOW AND MID LEVEL LAPSE RATES WILL BE RATHER STEEP...SO
THERE WILL BE A MINIMAL POTENTIAL OF SHOWERS WHEN COMBINED WITH THE
COLD AIR ALOFT AND MID/UPPER LEVEL ENERGY. HOWEVER...POPS WILL BE
LIMITED BELOW 15 PERCENT AT THIS TIME GIVEN THAT THE AIRMASS WILL BE
VERY DRY (SFC DEWPOINTS IN THE MID/UPPER 20S INLAND).
850MB TEMPERATURES DROP TO AROUND 0C MONDAY...WHICH IS AROUND -2 ST
DEV BELOW NORMAL PER 11/12Z GEFS MEAN. FULLY MIXED...AS EXPECTED
WILL RESULT IN HIGH TEMPERATURES RANGING FROM THE UPPER 50S N...TO
NEAR 65 FAR S...WHICH WOULD ALSO BE AROUND -2 ST DEV BELOW SEASONAL
MEANS. DAYTIME HIGHS MAY BE REACHED AROUND MIDDAY BEFORE DROPPING A
FEW DEGREES IN THE AFTERNOON AS CLOUD COVER INCREASES.
CANADIAN HIGH PRESSURE SETTLES OVER THE PIEDMONT MONDAY NIGHT INTO
TUESDAY MORNING. THE SKY SHOULD CLEAR MONDAY EVENING...WHICH WILL
EVENTUALLY RESULT IN A COOL START TO THE DAY TUESDAY. FORECAST LOWS
RANGE FROM THE MID 30S OVER THE PIEDMONT AND E/S-CENTRAL VA COASTAL
PLAIN TO THE LOW/MID 40S FOR SE COASTAL LOCATIONS. IF ANY FROST
POTENTIAL EXISTS...IT WOULD LIKELY BE OVER THE PIEDMONT WHERE FULL
DECOUPLING COULD OCCUR.
THE HIGH DRIFTS OFFSHORE TUESDAY. LIGHT ONSHORE FLOW WILL MAINTAIN
RATHER COOL HIGHS IN THE LOW 60S (STILL NEAR -1.5 ST DEV) NEAR THE
COAST...AND LIGHT RETURN FLOW SHOULD ALLOW HIGHS TO RISE INTO THE
UPPER 60S TO NEAR 70 OVER THE PIEDMONT UNDER A MOSTLY SUNNY SKY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
HI PRES WILL SLIDE INTO THE ATLC FOR TUE NGT THRU THU. A WARM
FRONT WILL SLOWLY LIFT THRU THE REGION AND OFFSHR LATE TUE NGT
THRU THU MORNG. AT THIS TIME...WILL MAINTAIN A DRY FCST DURING
THIS PERIOD...BUT ANY ISLTD PCPN WILL LIKELY OCCUR ACRS THE NRN
THIRD OF THE AREA. SLGT CHC FOR SHOWERS OR TSTMS...MAINLY ACRS THE
NRN HALF OF THE REGION THU AFTN INTO FRI MORNG...AS A WEAK TROF
MOVES THRU THE AREA. GOING WITH SLGT CHC FOR SHOWERS AND TSTMS
(OCCURRING MAINLY AFTN/EVENG HRS) FRI THRU SAT...IN RELATIVELY
WARM AND MARGINALLY UNSTABLE AIRMASS IN ADVANCE OF MAIN COLD FRONT
N OF THE REGION. MIN TEMPS WILL RANGE FM THE MID 40S TO LWR 50S
WED MORNG...AND MAINLY IN THE MID 50S TO LWR 60S THU...FRI...AND
SAT MORNGS. MAX TEMPS WILL RANGE THRU THE 70S WED...AND GENERALLY
IN THE UPR 70S TO MID 80S THU...FRI AND SAT.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
COLD FRNT CURRENTLY OVER WV WILL SLOWLY APPROACH THE MID ATLANTIC
THIS AFTERNOON. S/SW WINDS WILL OCCASIONALY GUST TO 20-25 MPH
THROUGH THE AFTN. SCATTER SHOWERS AND POSIBLE TSTMS ARE DEVELOPING
ACROSS THE AREA AHEAD OF THE COLD FRONT. TIMING OF THE
THUNDERSTORMS AT ANY GIVEN AIRPORT IS DIFFICULT AS THEY MOST
LIKELY WILL FORM IN VARIOUS GROUPS ON SMALL SCALE BOUNDARIES.
BELIEVE THE STRONGEST STORMS ARE LIKELY LATE THIS AFTERNOON AND
EVENING AND COULD SEE AN ISOLATED SEVERE STORM WITH BEST CHANCES
FOR IT TOWARD THE COAST. AFTER SUNSET WILL STILL SEE A NUMBER OF
SHOWERS AROUND BUT BELIEVE MOST OF THE THUNDER WILL END. COULD SEE
BRIED IFR CONDITIONS IN SOME OF THE EHAVIER THUNDERSTORMS THIS
AFTERNOON AND EVENING. OTHERWISE MAINLY VFR CONDTIONS. THESE SHOWERS WILL
END FROM WEST TO EAST AS THE COLD FRONT SLOWLY MOVES ACROSS THE
AREA. THE COLD FRONT MOVES OFF THE COAST DURING SUNDAY MORNING AND
SKIES WILL CLEAR WITH WINDS BECOMING NORTHWEST. VFR EXPECTED SUN
THRU THE MIDDLE OF NEXT WEEK WITH HI PRES IN PLACE.
&&
.MARINE...
NO HEADLINES IN THE SHRT TERM TNGT THRU MON. SSW WINDS 10 TO 20 KT
THIS EVENG...WILL BECOME W OR NW 10 TO 15 KT BY SUN MORNG AS THE
COLD FRONT MOVES TO JUST OFFSHR. NW OR N WINDS ARND 15 KT OR LESS
SUN MORNG INTO SUN AFTN...DUE TO MINOR SURGE BEHIND EXITING COLD
FRONT. ANOTHER NNW SURGE (SUB-SCA) EXPECTED SUN NGT INTO MON
MORNG...AS HI PRES BLDS TWD THE AREA FM THE W. THE HI WILL BLD
RIGHT OVR THE REGION LATE MON NGT THRU TUE...THEN SLIDES INTO THE
ATLC FOR TUE NGT INTO THU.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...TMG
AVIATION...JAB
MARINE...TMG
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
416 PM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT CROSSES THE MID ATLANTIC TONIGHT FOLLOWED BY A
SECONDARY COLD FRONT SUNDAY EVENING. CANADIAN HIGH PRESSURE BUILDS
INTO THE REGION MONDAY AND MONDAY NIGHT BRINGING A VERY COOL
AIR FOR THE MIDDLE OF MAY...BEFORE SLIDING OFF THE COAST TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE LATEST REGIONAL RADAR MOSAIC SHOWS ISOLATED TO SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE REGION MARGINALLY UNSTABLE AIRMASS
(~1000 J/KG OF MLCAPE) ALONG WITH MODEST DEEP LAYER SHEAR (30-40KT
0-6KM). CURRENT GOES WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH
LIFTING NE ACROSS PA ALONG WITH STRONGER SYNOPTIC SCALE
DYNAMICS...HENCE ANY STORMS ACROSS THE LOCAL AREA HAVE STRUGGLED TO
ORGANIZE AND PERSIST. THIS TREND IS EXPECTED TO CONTINUE OVER THE
NEXT FEW HOURS BEFORE A JET STREAK OVER THE TENNESSEE VALLEY EJECTS
NE ACROSS THE REGION AHEAD OF A FRONTAL ZONE APPROACHING FROM THE
WEST.
THE LATEST RUC BRINGS THE JET ACROSS THE AREA DURING THE MID-EVENING
THROUGH EARLY OVERNIGHT HOURS. GIVEN THIS...A BAND OF LIKELY POPS
WILL BE FORECAST TO MOVE W-E OVER THE CWA. HOWEVER...QPF AMOUNTS
SHOULD BE RATHER MINIMAL. THUNDER WILL BE MAINTAINED THROUGH
MIDNIGHT TO ACCOUNT FOR ANY LINGERING INSTABILITY BEFORE
TRANSITIONING TO ONLY SHOWERS AFTER MIDNIGHT. LOW TEMPERATURES SHOULD
RANGE FROM THE LOW 50S NW...TO LOW 60S SE.
SHORT TERM...
STEADY CAA COMMENCES SUNDAY AS THE COLD FRONT MOVES OFF THE COAST
SUNDAY MORNING AND HIGH PRESSURE BUILDS OVER THE MISSISSIPPI VALLEY.
THIS SHOULD PRODUCE A RATHER PLEASANT DAY WITH LOW-LEVEL THICKNESS
VALUES SUPPORTING HIGHS IN THE UPPER 60S N/NW...TO THE LOW/MID 70S
SE UNDER AN INCREASINGLY SUNNY SKY.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
STEADY CAA COMMENCES SUNDAY AS THE COLD FRONT MOVES OFF THE COAST
SUNDAY MORNING AND HIGH PRESSURE BUILDS OVER THE MISSISSIPPI VALLEY.
THIS SHOULD PRODUCE A RATHER PLEASANT DAY WITH LOW-LEVEL THICKNESS
VALUES SUPPORTING HIGHS IN THE UPPER 60S N/NW...TO THE LOW/MID 70S
SE UNDER AN INCREASINGLY SUNNY SKY.
A SECONDARY COLD FRONT SWINGS THROUGH THE REGION SUNDAY NIGHT. THE
CONTINUATION OF STEADY CAA OVERNIGHT WILL DRIVE LOW TEMPERATURES
DOWN INTO THE UPPER 30S N/NW TO THE MID/UPPER 40S FAR SE UNDER A
CLEAR SKY. THERE SHOULD BE ENOUGH MIXING ALONG WITH DRY AIR/LOW
DEWPOINTS TO INHIBIT ANY FROST DEVELOPMENT IN THE COLDER SPOTS.
VERY COLD AIR ALOFT FOR MID-MAY ARRIVES MONDAY DRIVING 1000-500MB
THICKNESS VALUES DOWN TO AROUND 532-540DAM. A STRONG VORT MAX/PV MIN
DIVES AROUND THE BACK-SIDE OF THE PARENT TROUGH DURING THE
AFTERNOON. THIS ENERGY DROPPING INTO THE TROUGH WILL DROP 500MB
HEIGHTS TO -2 TO -3 ST DEV PER 11/12Z GEFS MEAN AT 00Z TUESDAY.
GIVEN THIS...A BKN SC DECK IS EXPECTED TO DEVELOP DURING THE
AFTERNOON. LOW AND MID LEVEL LAPSE RATES WILL BE RATHER STEEP...SO
THERE WILL BE A MINIMAL POTENTIAL OF SHOWERS WHEN COMBINED WITH THE
COLD AIR ALOFT AND MID/UPPER LEVEL ENERGY. HOWEVER...POPS WILL BE
LIMITED BELOW 15 PERCENT AT THIS TIME GIVEN THAT THE AIRMASS WILL BE
VERY DRY (SFC DEWPOINTS IN THE MID/UPPER 20S INLAND).
850MB TEMPERATURES DROP TO AROUND 0C MONDAY...WHICH IS AROUND -2 ST
DEV BELOW NORMAL PER 11/12Z GEFS MEAN. FULLY MIXED...AS EXPECTED
WILL RESULT IN HIGH TEMPERATURES RANGING FROM THE UPPER 50S N...TO
NEAR 65 FAR S...WHICH WOULD ALSO BE AROUND -2 ST DEV BELOW SEASONAL
MEANS. DAYTIME HIGHS MAY BE REACHED AROUND MIDDAY BEFORE DROPPING A
FEW DEGREES IN THE AFTERNOON AS CLOUD COVER INCREASES.
CANADIAN HIGH PRESSURE SETTLES OVER THE PIEDMONT MONDAY NIGHT INTO
TUESDAY MORNING. THE SKY SHOULD CLEAR MONDAY EVENING...WHICH WILL
EVENTUALLY RESULT IN A COOL START TO THE DAY TUESDAY. FORECAST LOWS
RANGE FROM THE MID 30S OVER THE PIEDMONT AND E/S-CENTRAL VA COASTAL
PLAIN TO THE LOW/MID 40S FOR SE COASTAL LOCATIONS. IF ANY FROST
POTENTIAL EXISTS...IT WOULD LIKELY BE OVER THE PIEDMONT WHERE FULL
DECOUPLING COULD OCCUR.
THE HIGH DRIFTS OFFSHORE TUESDAY. LIGHT ONSHORE FLOW WILL MAINTAIN
RATHER COOL HIGHS IN THE LOW 60S (STILL NEAR -1.5 ST DEV) NEAR THE
COAST...AND LIGHT RETURN FLOW SHOULD ALLOW HIGHS TO RISE INTO THE
UPPER 60S TO NEAR 70 OVER THE PIEDMONT UNDER A MOSTLY SUNNY SKY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
CANADIAN HIGH PRS SETTLES OVR THE AREA TUE RESULTING IN A COOL BUT
DRY BEGINNING TO THE PRD. COMBO OF DECOUPLING WNDS...CLR SKIES AND
RTHR LOW DP TMPS ALLOWS FOR GOOD RADITIONAL COOLING MON NITE. LOWS
FM THE U30S NW PIEDMONT TO M-U40S AT THE BEACHES. M SUNNY & COOL
TUE. HIGHS 65-70...XCPT U50S-L60S NRN BEACHES. LOWS TUE NITE 45-50.
LEANED TOWARD THE ECMWF FOR THE REST OF THE PRD. HIGH PRS MOVES S
OF RGN WED WITH A WRM FRNT APPRCHG FROM THE WEST. KEPT IT DRY FOR
NOW AS IT APPEARS ANY PCPN ASSCTD WITH THIS BNDRY STAYS N&W OF FA.
RETURN FLOW AND WRMG H85 TMPS RESULTS IN READINGS RISING INTO THE
M-U70S W OF CHES BAY...M60S-L70S AT THE BEACHES.
WILL CONT TO WATCH FOR ANY CONVECTIVE COMPLEXES THAT DVLP IN NW FLOW
ARND THE HIGH TO THE SOUTH. MODELS HINTING AT THIS OCCURRING WED
NITE INTO THU. GIVEN LOW CONFIDENCE THIS FAR OUT...ELECTED TO ONLY
GO WITH SLGHT CHC POPS ACROSS NRN HALF OF FA THU WHERE BEST SPRT WUD
BE. LOWS WED NITE IN THE M-U50S MUCH WRMR THU WITH HIGHS L-M80S WEST
OF CHES BAY...70S AT THE COAST.
LEE TROF DVLPMNT AHEAD OF NEXT FRNT SEEN FOR FRI...THUS WENT WITH A
SLGHT CHC POPS. HIGHS 80-85...XCPT 70S AT THE COAST.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
COLD FRNT CURRENTLY OVER WV WILL SLOWLY APPROACH THE MID ATLANTIC
THIS AFTERNOON. S/SW WINDS WILL OCCASIONALY GUST TO 20-25 MPH
THROUGH THE AFTN. SCATTER SHOWERS AND POSIBLE TSTMS ARE DEVELOPING
ACROSS THE AREA AHEAD OF THE COLD FRONT. TIMING OF THE
THUNDERSTORMS AT ANY GIVEN AIRPORT IS DIFFICULT AS THEY MOST
LIKELY WILL FORM IN VARIOUS GROUPS ON SMALL SCALE BOUNDARIES.
BELIEVE THE STRONGEST STORMS ARE LIKELY LATE THIS AFTERNOON AND
EVENING AND COULD SEE AN ISOLATED SEVERE STORM WITH BEST CHANCES
FOR IT TOWARD THE COAST. AFTER SUNSET WILL STILL SEE A NUMBER OF
SHOWERS AROUND BUT BELIEVE MOST OF THE THUNDER WILL END. COULD SEE
BRIED IFR CONDITIONS IN SOME OF THE EHAVIER THUNDERSTORMS THIS
AFTERNOON AND EVENING. OTHERWISE MAINLY VFR CONDTIONS. THESE SHOWERS WILL
END FROM WEST TO EAST AS THE COLD FRONT SLOWLY MOVES ACROSS THE
AREA. THE COLD FRONT MOVES OFF THE COAST DURING SUNDAY MORNING AND
SKIES WILL CLEAR WITH WINDS BECOMING NORTHWEST. VFR EXPECTED SUN
THRU THE MIDDLE OF NEXT WEEK WITH HI PRES IN PLACE.
&&
.MARINE...
SOUTHERLY FLOW CONTINUES TDY WITH HI PRES WELL OFFSHORE AND A COLD
FRNT APPROACHING FROM THE WEST. WILL MAINTAIN INHERITED SCA OVER THE
BAY WITH WINDS CURRENTLY GUSTING TO NEAR SCA CRITERIA...CONTINUING
AT TIMES THRU THE DAY AHEAD OF THE FRNT. SEAS HAVE BEEN SLOW TO BLD
HOWEVER 44009 HAS NOW MADE IT TO 4 FT AND EXPECT NORTHERN COASTAL
WATERS TO GET TO 5 FT LATER THIS MRNG THRU LATE AFTN. WILL HOLD OFF
ON ANY HEADLINES SOUTH OF PARRAMORE ISLAND WHERE 3-4 FT SEAS ARE
EXPECTED. WINDS WILL STAY SUB-SCA OVER THE RIVERS AND SOUND...WITH
THE LWR JAMES BEING CLOSE TO CRITERIA. THE COLD FRNT CROSSES THE
WATERS TNGT BUT WITH WEAKENING WINDS BEHIND THE FRNT WILL END THE
SCA AT 7 PM. SECONDARY SURGE MAY PRODUCE NW WINDS UP TO 15 KT SUN
AFTN. OTHERWISE...SUB-SCA CONDS FOR SUN THRU THE MIDDLE OF NEXT
WEEK AS SFC HI PRES BLDS INTO THE AREA.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...MPR
AVIATION...MAS/JAB
MARINE...MAS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
719 PM EDT SUN MAY 12 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 404 PM EDT SUN MAY 12 2013
WV IMAGERY AND RUC ANALYSIS INDICATED AN AMPLIFIED PATTERN WITH A
RIDGE OVER WRN NOAM AND A TROUGH OVER THE EAST. THE MID LEVEL LOW
CENTER WAS SLOWLY MOVING OFF TO THE EAST OF CYSB INTO QUEBEC. AT THE
SFC...THE PRES GRADIENT ACROSS LAKE SUPERIOR WAS GRADUALLY WEAKENING
AS THE 998 MB LOW ALSO MOVES INTO QUEBEC AND A RIDGE RIDGE FROM NW
ONTARIO THROUGH WRN MN BUILDS INTO THE UPPER MS VALLEY. RADAR
INDICATED THAT THE LINGERING FLURRIES BTWN MQT-ESC-ISQ WERE
DIMINISHING AS DRIER AIR MOVES IN .
TONIGHT...EXPECT THAT THE REST OF THE LOWER CLOUDS WILL DISSIPATE
DURING THE LATE AFTERNOON AND EARLY EVENING...PER SATELLITE
TRENDS...BUT MAY LINGER A BIT LONGER THAN WHAT SHORT TERM MODEL LOW
LEVEL RH GUIDANCE SUGGESTS. WITH GOOD RADIATIONAL COOLING CONDITIONS
BY LATE THIS EVENING WEST AND OVER NIGHT EAST AND PWAT VALUES BELOW
0.25 INCH...MIN TEMPS SHOULD FALL TOWARD THE LOWER END OF GUIDANCE
AND NEAR RECORD VALUES. THE RECORD FOR THE NWS OFFICE ON 5/12 IS 24
AND ON 5/13 IS 25. READINGS INTO THE UPPER TEENS INTERIOR WEST TO THE
MID 20S EAST ARE EXPECTED WHILE TEMPS AROUND 30 PREVAIL NEAR THE
GREAT LAKES.
MONDAY...AS THE MID/UPPER LEVEL RIDGE OVER THE PLAINS BUILDS TO THE
EAST...A BROAD WAA PATTERN WILL DEVELOP OVER THE UPPER MS VALLEY AND
WRN GREAT LAKES. 295-305K ISENTRPOPIC ASCENT AHEAD OF A TROUGH
MOVING TOWARD MN WILL BRING INCREASING HIGH CLOUDS ACROSS UPPER MI
DURING THE AFTERNOON. THE INITIAL DRY LOW LEVELS AHEAD OF THE BAND
OF MOISTURE/ASCENT WILL LIMIT EASTWARD PROGRESSION OF THE LIGHT PCPN
BAND TO THE FAR WEST DURING THE LATE AFTERNOON WHERE ONLY SLIGHT
CHANCE POPS WERE INCLUDED.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 157 PM EDT SUN MAY 12 2013
SLY FLOW WILL DOMINATE BETWEEN A SFC RIDGE OVER THE ERN CWA AND A
TROUGH OVER THE MN/ND/SD BORDERS AT 00Z TUE. WAA AND ASSOCIATED THIN
BAND OF LIGHT SHOWERS WILL BE OVER THE WRN CWA. COVERAGE OF THESE
RAIN SHOWERS WILL BE LIMITED BY LIMITED MOISTURE...SO WILL KEEP POPS
ON THE LOWER SIDE SIMILAR TO LAST FORECAST. THE PRECIP MOVES TO THE
FAR ERN CWA BY 12Z TUE.
BY 00Z WED...A SHORTWAVE TROUGH AND SFC LOW WILL MOVE TO SRN
MANITOBA...BRINGING A WARM FRONT INTO THE CWA AND A COLD FRONT TO
CENTRAL MN. BY THIS TIME...850MB TEMPS WILL HAVE INCREASED TO AROUND
16C OVER THE WRN CWA AND 9C OVER THE ERN CWA /14C AND 11C WARMER
THAN 24 HOURS BEFORE...RESPECTIVELY/. THE WARM FRONT WILL MOVE
THROUGH THE CWA FOLLOWED SHORTLY AFTER BY THE COLD FRONT WED NIGHT
INTO EARLY WED. WHILE THUNDERSTORMS APPEAR LIKELY GIVEN INSTABILITY
AND STEEP LAPSE RATES...THERE IS SOME UNCERTAINTY WITH CONVECTIVE
STRENGTH. MODEL FORECAST SOUNDINGS INDICATE POTENTIAL FOR OVER
1000J/KG OF ELEVATED CAPE...BUT MODELS SHORT THE DRY SLOT ROTATING
THROUGH AROUND THE SAME TIME AS THE SHORTWAVE...BRINGING AN ELEVATED
MIXED LAYER THAT LEADS TO 100-200J/KG OF CIN. WHETHER THE COLD FRONT
CAN LIFT PARCELS THROUGH THE DRY LAYER AND THE EXACT TIMING OF THE
DRYER AIR REALLY LOWERS CONFIDENCE IN STRONGER THUNDERSTORMS.
ALSO...MODELS NOW AGREE FAIRLY WELL ON TIMING OF THE SYSTEM...BUT
VARY MORE SIGNIFICANTLY ON HOW FAR N OR S TO BRING THE
SYSTEM...WHICH IMPACTS POTENTIAL FORCING FOR ASCENT AND THE STRENGTH
OF THE LOW LEVEL JET. PRECIP DOES APPEAR LIKELY ENOUGH WED NIGHT TO
GO WITH LIKELY POPS /AT LEAST OVER THE NRN AND ERN CWA/...AND
THUNDER ALSO SEEMS LIKE A GOOD BET IN MOST LOCATIONS THAT RECEIVE
RAIN. DEFINITELY NOT SURE ON SEVERE POTENTIAL YET...BUT THERE IS
SOME INDICATION THAT ISOLATED SEVERE WX MAY BE POSSIBLE.
EVEN THOUGH 850MB TEMPS ARE COOLER DURING THE DAY WED THAN
TUE...GOOD MIXING AND SUNSHINE BEHIND THE COLD FRONT WILL LEAD TO
WARMER HIGH TEMPS AND LOWER RH VALUES...COMBINED WITH BREEZY WLY
WINDS. EXPECT HIGHS IN THE 70S INLAND...WITH AROUND 60 EXPECTED
CLOSER TO LAKE SUPERIOR. WILL CONTINUE TREND FROM PREVIOUS SHIFT OF
LOWERING DEW PTS LOWER GIVEN GOOD MIXING AND DRY AIRMASS BEHIND THE
FRONT...LEADING TO MIN RH VALUES IN THE 25-30 PERCENT /OR LOWER/
RANGE OVER INTERIOR CENTRAL AND WEST UPPER MI. INCREASED WINDS ON WED
TO GUSTS TO 30KTS OVER THE WRN CWA /COULD BE HIGHER IF NAM
VERIFIES...BUT IT IS ON THE STRONGER SIDE/. IT IS WORTH NOTING THAT
THE WARMEST TEMPS...LOWEST RH AND HIGHEST WINDS ARE EXPECTED OVER
THE INTERIOR WRN CWA...WHERE THE CHANCES FOR SIGNIFICANT PRECIP TUE
NIGHT ARE THE LOWEST. WILL NEED TO CONTINUE TO MONITOR CONDITIONS
FOR WED...BUT MAY SEE CRITICAL FIRE WEATHER CONDITIONS OVER AT LEAST
PORTIONS OF UPPER MI.
HIGH TEMPS WILL BE A A DEGREE OR TWO COOLER THU...BUT STILL EXPECT
70S INLAND AND AROUND 60 NEAR LAKE SUPERIOR. MIN RH VALUES LOOK TO
BE SIMILAR TO WED ON THE LOW END OF THE COMFORT SCALE FOR FIRE
WX...BUT WINDS WILL BE MUCH LIGHTER AS BROAD HIGH PRESSURE SETTLES
OVER THE REGION.
FOR FRI THROUGH SUN...JUST LOADED A CONSENSUS OF MODEL GUIDANCE DUE
TO INCREASED UNCERTAINTY AND GREATER FOCUS ON FORECAST TUE-THU.
OVERALL...EXPECT TEMPS AROUND SEASONAL NORMALS /A REGULAR SEASONAL
NORMAL...NOT THIS SEASONS NORMAL/ WITH HIGHS IN THE 60S TO LOW 70S.
PRECIP WILL BE POSSIBLE AS FRONTAL ZONES WILL BE NEARBY...BUT
GETTING TOO SPECIFIC AT THIS POINT WOULD BE FUTILE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 718 PM EDT SUN MAY 12 2013
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH THE PERIOD.
APPROACH OF NEXT WEATHER DISTURBANCE LATE MON AFTERNOON WILL BRING A
LOW TO MID DECK OF CLOUDS...BUT SHOULD STILL STAY VFR.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 404 PM EDT SUN MAY 12 2013
GALES WILL SUBSIDE BY EARLY EVENING AND WINDS OVER THE EAST WILL
DROP BELOW 20 KNOTS OVERNIGHT AS A RIDGE BUILDS INTO THE REGION
WINDS WILL INCREASE OUT OF THE S/SE TO 25 KTS MON NIGHT THROUGH TUE
NIGHT AHEAD OF A LOW PRESSURE SYSTEM MOVING NORTH OF LAKE SUPERIOR
ON WED. A WARM FRONT SLIDING ACROSS LAKE SUPERIOR TUESDAY NIGHT AHEAD
OF THE LOW MAY RESULT IN A FEW STRONGER THUNDERSTORMS. LIGHTNING AND
HEAVY DOWNPOURS WOULD BE THE PRIMARY HAZARDS. EXPECT WINDS TO SHIFT
WESTERLY ON WEDNESDAY BEHIND THE COLD FRONT. POSSIBLE THAT GUSTS
COULD REACH 30 KTS. LIGHTER WINDS ARE EXPECTED AGAIN LATE IN THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
449 PM EDT SAT MAY 11 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 447 PM EDT SAT MAY 11 2013
WV IMAGERY AND RUC ANALYSIS INDICATED AN AMPLIFIED MID/UPPER LEVEL
PATTERN WITH A TROUGH FROM HUDSON BAY INTO THE WESTERN GREAT LAKES.
THE MID LEVEL LOW CENTER HAD DROPPED TO NEAR CYQT AS THE SHORTWAVE
TROUGH THAT SUPPORTED THE MORNING PCPN BAND SHIFTED INTO ERN UPPER
MI AND LAKE SUPERIOR. RADARS INDICATED THAT SCT -SHSN SUPPORTED BY
DIURNAL HEATING AND INFLUX OF COLDER AIR AND WRAP-AROUND MOISTURE
WERE SPREADING FROM NE MN AND WRN LAKE SUPERIOR INTO WRN UPPER MI.
UPSTREAM...THE 12Z CYPL SOUNDING INDICATED PLENTIFUL MOISTURE TO
INVERSION AROUND 12K FT(650)MB.
TONIGHT...MAINLY LIGHT SNOW SHOWERS ARE EXPECTED LATE THIS AFTERNOON
AND EVENING ACROSS THE WEST. HIGHER RES MODELS SUGGEST SHSN WILL
EXPAND IN COVERAGE AND INTENSITY ACROSS THE WEST FROM 00Z-03Z AND
INTO THE ERN CWA MAINLY AFT 03Z. WITH VERY FAVORABLE CONDITIONS FOR
LAKE ENHANCED SNOW DEVELOPING...SEVERAL INCHES OF SNOW WILL BE
POSSIBLE OVERNIGHT.
WITH CAA INCREASING AND WINDS VEERING AS A SECONDARY SHRTWV MOVES
THROUGH...TEMPS AT 850 MB FALL TO AROUND -8C WITH INVERSION TOP
TEMPS TO NEAR -18C...PER NAM. ALTHOUGH LAKE INDUCED CAPES ARE
RELATIVELY MODEST...MOISTURE THROUGH 650 MB AND SHARP CYCLONIC
LOW-LEVEL FLOW WILL BOOST CONVERGENCE AND ALLOW FOR AT A PERIOD OF
HEAVIER LAKE ENHANCED SNOW DOWNWIND OF LONGER FETCH OVER CNTRL AND
ERN LAKE SUPERIOR. SNOW ACCUMULATIONS IN THE 1 TO 4 INCH RANGE ARE
POSSIBLE WITH THE GREATEST AMOUNTS IN THE HIGHER TERRAIN FROM THE
HURON MOUNTAINS TO NEGAUNEE AND FROM ALGER COUNTY THROUGH NRN
SCHOOLCRAFT AND NRN LUCE COUNTY.
IN ADDITION TO THE SNOW...VERY STRONG WINDS ARE EXPECTED AFT 03Z AS
A PRES RISE MOVES THROUGH AND THE GRADIENT TIGHTENS WITH THE SFC LOW
DEEPENING E OF LAKE SUPERIOR. MIXED LAYER WINDS TO 40-45 KNOTS SUGGEST
POTENTIAL FOR WIND GUSTS TO AROUND 45 MPH IN EXPOSED LOCATIONS NEAR
THE LAKE SUPERIOR SHORELINE FROM MARQUETTE EASTWARD. A WINTER WEATHER
ADVISORY WAS ISSUED FOR THE COMBINATION OF WINDS AND SNOW.
SUN...WITH LINGERING DEEP CYCLONIC NNW FLOW AND AROUND -10C 8H
TEMPS MOVING ACROSS LAKE SUPERIOR IN THERMAL TROUGH...EXPECT SOME
LINGERING RAIN/SNOW SHOWERS EARLY IN THE MORNING OVER THE EAST WHERE
LONGER FETCH WILL BE MORE FAVORABLE FOR LAKE EFFECT EFFECT PCPN.
OTHERWISE...SHARP SUBSIDENCE/DRYING WITH A TRANSITION TO MORE NEUTRAL
OR ANTICYCLONIC FLOW FROM THE WEST BY AFTERNOON SHOULD BRING AND END
TO ANY LINGERING BY MID AFTERNOON. FAIRLY TIGHT NW PRES GRAD ON THE
BACKSIDE OF EXITING LOW WILL KEEP WINDS GUSTING TO NEAR 35 MPH OVER
THE ERN HALF COUNTIES ESPECIALLY NEAR LAKE SUPERIOR.
OTHERWISE...UNSEASONABLY COLD CONDITIONS WILL CONTINUE WITH HIGHS
RANGING FROM AROUND 40 NORTH AND EAST TO MID 40S SOUTH CENTRAL.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 447 PM EDT SAT MAY 11 2013
RELATIVELY COLD HIGH TEMPS ARE EXPECTED FOR SUN...SO GOING INTO SUN
NIGHT WITH SFC RIDGING AND ASSOCIATED CLEARING BUILDING IN FROM THE
W...SHOULD SEE SFC TEMPS FALL SHARPLY /ESPECIALLY OVER THE WRN
CWA/...EVEN THOUGH TEMPS ALOFT WARM SUN NIGHT. EXPECT LOWS SUN NIGHT
AROUND 20F /EVEN IN THE MID-UPPER TEENS IN COLDER SPOTS/ OVER
PORTIONS OF INTERIOR W UPPER MI...WITH LOWS AROUND OF BELOW FREEZING
IN MOST LOCATIONS. LOWERED TEMPS A FEW DEGREES IN COLDER SPOTS GIVEN
GUIDANCE COMING IN WITH COLDER TEMPS...BUT DID NOT GO AS LOW AS
COLDEST GUIDANCE.
SHOULD SEE 850MB TEMPS BETWEEN 18Z SUN AND 00Z TUE INCREASE BY 5C
OVER THE ERN CWA AND 12C OVER THE WRN CWA. THEREFORE...WILL SEE
WARMER TEMPS FOR MON THAN SUN...ESPECIALLY OVER THE WRN CWA. HIGH
TEMPS FOR MON ARE EXPECTED TO BE AROUND 60 OVER THE INTERIOR WRN CWA
AND AROUND 50 OVER THE FAR ERN CWA. COULD SEE SOME WAA PRECIP MOVING
ACROSS THE CWA LATE MON INTO MON NIGHT...BUT MOISTURE AND FORCING DO
NOT LOOK THAT IMPRESSIVE SO WILL KEEP POPS ON THE LOW END MON INTO
MON NIGHT.
MODELS HINT AT PRECIP FOR TUE ALONG A WARM FRONT AHEAD OF A
SHORTWAVE AND SFC LOW THAT MOVE INTO SRN MANITOBA BY 00Z WED.
AGAIN...MOISTURE AND FORCING WILL BE LIMITED SO WILL KEEP POPS LOW.
THUNDERSTORMS WILL BE POSSIBLE WITH THE PRECIP GIVEN ELEVATED
INSTABILITY AND DECENT LAPSE RATES. 850MB TEMPS INCREASE ANOTHER 13C
OVER THE WRN CWA TO 16C BETWEEN 00Z TUE AND 00Z WED...AND INCREASE
ANOTHER 10C TO 9C OVER THE FAR ERN CWA. SHOULD BE ABLE TO GET HIGHS
AROUND 70 OVER THE INTERIOR WRN CWA AND AROUND 60 OVER THE ERN CWA.
THE SFC LOW AND SHORTWAVE MOVE N OF THE CWA TUE NIGHT INTO
WED...WITH MODEL DISCREPANCIES ON TIMING OF THE SYSTEM. THIS BRINGS
A COLD FRONT ACROSS THE CWA BY AT LEAST 18Z WED /SLOWER GFS
TIMING/...WHICH WILL TURN WINDS OUT OF THE WNW AND COOL TEMPS A BIT.
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE POSSIBLE. MOISTURE
WILL BE MORE LIMITED ALONG THE SRN CWA...SO WILL KEEP POPS LOWER
THERE. WILL GO WITH LIKELY POPS OVER THE NRN/ERN CWA WHERE MOISTURE
AND FORCING WILL BE BETTER. EVEN WITH COOLER OVERHEAD
AIRMASS...AFTER THE FRONT PASSES WED MORNING...SKIES WILL CLEAR
OUT...ALLOWING SFC TEMPS TO WARM UP HIGHER THAN THE CLOUDIER TUE
AWAY FROM LAKE SUPERIOR. HIGHS LOOK TO BE IN THE MID 70S OVER THE
SCENTRAL CWA WED...AND AROUND 70S ELSEWHERE OVER THE INTERIOR CWA.
THU THROUGH NEXT SAT...CONFIDENCE IS LOWERED BY LACK OF MODEL
AGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST RUN WITH WHATEVER
CONSENSUS OF MODELS COMES UP WITH FOR THIS TIME PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 447 PM EDT SAT MAY 11 2013
A PERIOD WITH CIGS JUST ABOVE MVFR THIS AFTERNOON IS EXPECTED TO
GIVE WAY TO MVFR CONDITIONS LATE THIS AFTERNOON AND EARLY EVENING AS
COLDER AIR MOVES INTO THE REGION ON NW WINDS. A PERIOD OF LAKE
ENHANCED SNOW AT CMX AND SAW LATE THIS EVENING AND OVERNIGHT SHOULD
DROP VSBY INTO THE IFR RANGE. GRADUAL IMPROVING CONDITIONS EXPECTED
AT ALL TAF SITES ON SUNDAY AS HIGH PRESSURE AND DRIER AIR ARRIVES.
INCREASING NORTHWEST WINDS WILL OCCUR AT ALL TAF SITES. STRONGEST
WINDS OVER 30 KTS ARE EXPECTED AT CMX LATE THIS AFTN THROUGH THE
EVENING...THEN AT SAW FROM LATE EVENING THROUGH THE REST OF THE
NIGHT.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 447 PM EDT SAT MAY 11 2013
EXPECT A STRONG GALE TO DEVELOP OVER MOST OF THE LAKE BY LATE THIS
EVENING AND LASTING INTO AT LEAST SUN MORNING BEFORE DIMINISHING. A
GALE WARNING REMAINS IN EFFECT FOR MUCH OF LK SUPERIOR FOR WINDS
40-45 KTS. RIDGING MOVES OVER LAKE SUPERIOR SUN NIGHT AND
MON...LEADING TO RELATIVELY CALM WINDS. WINDS WILL INCREASE OUT OF
THE S MON NIGHT THROUGH TUE NIGHT AHEAD OF A LOW PRESSURE SYSTEM
THAT WILL MOVE N OF LAKE SUPERIOR WED...BRINGING A SOUTHWEST SHIFT
TO THE WINDS WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 8 AM EDT
SUNDAY FOR MIZ006-007-085.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 8 AM EDT
SUNDAY FOR MIZ005.
LAKE SUPERIOR...
GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EDT SUNDAY FOR LSZ251-
267.
GALE WARNING FROM 10 PM THIS EVENING TO 6 PM EDT SUNDAY FOR
LSZ249-250-266.
GALE WARNING FROM 8 PM THIS EVENING TO 2 PM EDT SUNDAY FOR
LSZ243>245-264-265.
GALE WARNING FROM 10 PM THIS EVENING TO 8 AM EDT SUNDAY FOR
LSZ248.
GALE WARNING FROM 8 PM THIS EVENING TO 8 AM EDT SUNDAY FOR
LSZ263.
LAKE MICHIGAN...
GALE WARNING FROM MIDNIGHT TONIGHT TO 8 AM EDT SUNDAY FOR LMZ250.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1230 PM EDT SAT MAY 11 2013
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 334 AM EDT SAT MAY 11 2013
A COLD FRONT WILL MOVE THROUGH LOWER MICHIGAN TODAY BRINGING SHOWERS
WITH IT. COOLER WEATHER WILL FOLLOW FOR SUNDAY WITH WIDESPREAD FROST
EXPECTED SUNDAY NIGHT. A DRAMATIC WARM UP WILL DEVELOP EARLY NEXT
WEEK WITH HIGHS REACHING THE 80S MIDWEEK.
&&
.UPDATE...
ISSUED AT 1106 AM EDT SAT MAY 11 2013
NOTICED SOME LIGHTNING WITH THE CELL WEST OF LITTLE SABLE POINT.
BASED ON THIS I ADDED THUNDER TO THE FORECAST FOR SOUTHWEST MI
THIS AFTERNOON. THIS FRONT WILL MOVE QUICKLY THROUGH THE REGION
THIS AFTERNOON. BY 22Z IT SHOULD BE EAST OF LANSING. POPS WERE
ADJUSTED SLIGHTLY BECAUSE OF THE FASTER FRONTAL MOVEMENT.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 334 AM EDT SAT MAY 11 2013
FORECAST CONCERNS DEAL WITH PCPN TRENDS TODAY AND FROST/FREEZE
CHANCES TONIGHT AND SUNDAY NIGHT.
LOW PRESSURE OVER WISCONSIN WILL DRAG A COLD FRONT ACROSS THE CWA
THIS AFTERNOON. REGIONAL RADAR SHOWS A BROKEN LINE OF SHOWERS MOVING
ACROSS THE UPPER MIDWEST. LOOK FOR THIS TO FILL IN A BIT BETTER THIS
AFTERNOON. WE DON/T EXPECTED TO MUCH RAIN WITH THIS AS MOISTURE IS
SOMEWHAT LIMITED. CAN/T RULE OUT THUNDER AS MUCAPES ARE IN THE
150-200 J/KG RANGE BUT OVERALL INSTABILITY IS ON THE LOW SIDE.
COLDER AIR WILL FLOW INTO THE CWA TONIGHT AND FROST IS POSSIBLE OVER
THE NRN 2 TIERS OF COUNTIES. COLD ADVECTION WILL CONTINUE SUNDAY AS
H8 TEMPS FALL TO -8C WHICH WILL YIELD LAKE DELTA T/S AROUND 13C.
SHOULD SEE SOME LAKE CLOUDS WITH THIS SETUP ALONG WITH A CHANCE OF
SHOWERS...SOME OF WHICH MAY BE MIXED WITH SNOW OVER THE NRN CWA.
AS THE UPPER TROUGH MOVES AWAY SUNDAY NIGHT SKIES SHOULD CLEAR AND
TEMPS WILL FALL INTO THE 20S/LWR 30S. WIDESPREAD FROST IS EXPECTED
WITH FREEZING TEMPS OVER MUCH OF THE CWA. A FREEZE WARNING MAY BE
NEEDED SUNDAY NIGHT.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 334 AM EDT SAT MAY 11 2013
TYPICAL OF SPRING IN MICHIGAN OUR WARM THEN COLD THEN WARM AGAIN
WEATHER PATTERN WILL CONTINUE. MY ISSUE TODAY IS MOSTLY FOCUSED ON
WHAT HAPPENS TO THE FRONT THAT MOVES INTO THE AREA WEDNESDAY... DOES
IT STALL NEAR SOUTHWEST MICHIGAN PUTTING US BACK INTO A RAINY
PATTERN OR DOES IT SLIP FAR ENOUGH SOUTH TO DRY US OUT LATE THIS
COMING WEEK?
THE LARGE SCALE PATTERN CONTINUES TO FEATURE A HIGH AMPLITUDE UPPER
AIR PATTERN WITH CONSIDERABLE MERIDIONAL FLOW (WHY IT IS GETTING SO
COLD THIS WEEKEND). ALL OF THE OPERATIONAL MEDIUM RANGE MODELS
CONTINUE TO SUGGEST THIS PATTERN WILL FLATTEN OUT EARLY THIS COMING
WEEK. WE END UP WITH ONE OF THOSE EXTENDED EAST ASIAN JET FEATURES
BY MIDWEEK. TYPICALLY FOR SOUTHWEST MICHIGAN THAT MEANS WARMER THAN
NORMAL TEMPERATURES AND FREQUENT SHORTWAVES PRODUCING FREQUENT
PERIODS OF PRECIPITATION. ALL OF THIS HAS BEEN AND CONTINUES TO BE
THE MAIN ASPECT OF THE CHANGING UPPER AIR PATTERN. SO THE QUESTION
BECOMES... DOES THE FLATTER FLOW FORECAST BY THE ECMWF FROM
WEDNESDAY ON BECOME THE TRUE PATTERN OR WILL THE MORE AMPLIFIED
PATTERN OF THE GFS PREVAIL (THAT WOULD BE DRIER AND COOLER FOR
SOUTHWEST MICHIGAN)?
THERE ARE TWO CONCERNS OF MINE AS TOO WHY I QUESTION THE ECMWF THIS
TIME. FIRST IS THE SYSTEM MOVING ONTO THE WEST COAST CURRENTLY IS A
VERY DEEP TROUGH WITH A STRONG PACIFIC SYSTEM MOVING THROUGH THE
BASE OF THE TROUGH (JUST OFF THE OR/WA COAST). THE ECMWF FLATTENS
THIS WAVE AMAZINGLY FAST GIVEN ITS CURRENT AMPLITUDE. ALSO BOTH THE
ECMWF AND GFS SHOW A CLOSE UPPER HIGH DEVELOPING BY TUESDAY JUST
SOUTH OF GREENLAND. THAT THEN PERSISTS ON BOTH MODELS THROUGH THE
REST OF THE WEEK. OUR UPPER AIR FLOW WILL BE BLOCKED TO OUR EAST.
GIVEN THE BLOCKING TO THE EAST AND STRENGTH OF THE PACIFIC SYSTEM
MOVING ON SHORE (OUR WEDNESDAY SYSTEM) I WOULD HAVE TO FAVOR THE GFS
AT THIS POINT(MORE AMPLIFIED UPPER AIR PATTERN).
THE MORE AMPLIFIED PATTERN WOULD SUPPORT A STRONG COLD FRONT
WEDNESDAY EVENING WITH STRONGER THUNDERSTORMS BUT IT WOULD ALSO MEAN
A WARMER WEDNESDAY... THICKNESS VALUES AND 850 AND 925 MB TEMPS ARE
FORECAST TO BE AS WARM ENOUGH FOR LOWER TO MID 80S WEDNESDAY. SO I
HAVE TO IMAGINE EVEN WITH SOME FRONTAL CLOUDS AROUND MOST INLAND
AREAS SHOULD SEE HIGHS INTO THE LOWER 80S WEDNESDAY. WITH THAT MORE
AMPLIFIED PATTERN THE FRONT WOULD GO SOUTH OF MICHIGAN THURSDAY AND
IT WOULD COOL OFF SOME FOR THE REST OF THE WEEK.
IF THE ECMWF IS CORRECT... THE UPPER LOW OVER THE SW CONUS GETS
BOOTED EAST NORTHEAST TOWARD THE GREAT LAKES AND THAT BRING US A
STALLED FRONT WITH PERIODS OF SHOWERS AND THUNDERSTORMS WEDNESDAY
THROUGH FRIDAY (AND BEYOND).
FOR NOW I WILL SLIGHTLY FAVOR THE GFS AND KEEP POPS LOW WED THROUGH
FRIDAY. WE SHALL SEE HOW THIS PLAYS OUT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1230 PM EDT SAT MAY 11 2013
A COLD FRONT WILL BRING SCATTERED SHOWERS THROUGH MID AFTERNOON.
WINDS FROM MID TO LATE AFTERNOON WILL GUST TO 25 TO 30 KTS OUT OF
THE WNW BEFORE DECREASING TONIGHT. PRIMARILY IFR/MVFR CONDITIONS
THIS AFTERNOON WILL IMPROVE TO VFR LATE THIS AFTERNOON AND TONIGHT.
VFR CONDITIONS SHOULD THEN CONTINUE THRU 18Z SUN AND WNW WINDS WILL
INCREASE TO 15 TO 20 KTS WITH GUSTS TO AROUND 25 KTS BEGINNING MID
MORNING SUNDAY.
&&
.MARINE...
ISSUED AT 1106 AM EDT SAT MAY 11 2013
STRONGER GUSTS TO GALE FORCE ASSOCIATED WITH THE COLD FRONT ARE
SHOWN ON THE HRRR RUC. FSL RUC HAD GUSTS OVER 30 KNOTS. STABILITY
OF THE LAKE MAY BE AN ISSUE...LIMITING THIS RISK. SO FAR THE HRRR
IS VERIFIY WELL WITH THE UPSTREAM GUSTS. WENT AHEAD AND ISSUED A
GALE WARNING. THE WINDS WILL BE SHIFTING SHARPLY...ADDING TO THE
HAZARD. BY 00Z A LULL IN THE WINDS IS FORECASTED...SO THE GALE
WARNING IS OF A SHORTER DURATION. MAY NEED TO EXTEND IT AS THE
WINDS WILL PICK BACK UP BY DAYBREAK SUNDAY.
&&
.FIRE WEATHER...
ISSUED AT 334 AM EDT SAT MAY 11 2013
SHOWERS ARE EXPECTED MAINLY THIS AFTERNOON. COOLER TEMPERATURES WILL
FOLLOW SUNDAY WITH HIGHS IN THE 40S.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT SAT MAY 11 2013
RAINFALL LESS THAN A QUARTER INCH TODAY WILL HAVE A NEGLIGIBLE
EFFECT ON RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...93
SHORT TERM...93
LONG TERM...WDM
AVIATION...LAURENS
FIRE WEATHER...93
HYDROLOGY...93
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1112 AM EDT SAT MAY 11 2013
LATEST UPDATE...
UPDATE/MARINE
.SYNOPSIS...
ISSUED AT 334 AM EDT SAT MAY 11 2013
A COLD FRONT WILL MOVE THROUGH LOWER MICHIGAN TODAY BRINGING SHOWERS
WITH IT. COOLER WEATHER WILL FOLLOW FOR SUNDAY WITH WIDESPREAD FROST
EXPECTED SUNDAY NIGHT. A DRAMATIC WARM UP WILL DEVELOP EARLY NEXT
WEEK WITH HIGHS REACHING THE 80S MIDWEEK.
&&
.UPDATE...
ISSUED AT 1106 AM EDT SAT MAY 11 2013
NOTICED SOME LIGHTNING WITH THE CELL WEST OF LITTLE SABLE POINT.
BASED ON THIS I ADDED THUNDER TO THE FORECAST FOR SOUTHWEST MI
THIS AFTERNOON. THIS FRONT WILL MOVE QUICKLY THROUGH THE REGION
THIS AFTERNOON. BY 22Z IT SHOULD BE EAST OF LANSING. POPS WERE
ADJUSTED SLIGHTLY BECAUSE OF THE FASTER FRONTAL MOVEMENT.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 334 AM EDT SAT MAY 11 2013
FORECAST CONCERNS DEAL WITH PCPN TRENDS TODAY AND FROST/FREEZE
CHANCES TONIGHT AND SUNDAY NIGHT.
LOW PRESSURE OVER WISCONSIN WILL DRAG A COLD FRONT ACROSS THE CWA
THIS AFTERNOON. REGIONAL RADAR SHOWS A BROKEN LINE OF SHOWERS MOVING
ACROSS THE UPPER MIDWEST. LOOK FOR THIS TO FILL IN A BIT BETTER THIS
AFTERNOON. WE DON/T EXPECTED TO MUCH RAIN WITH THIS AS MOISTURE IS
SOMEWHAT LIMITED. CAN/T RULE OUT THUNDER AS MUCAPES ARE IN THE
150-200 J/KG RANGE BUT OVERALL INSTABILITY IS ON THE LOW SIDE.
COLDER AIR WILL FLOW INTO THE CWA TONIGHT AND FROST IS POSSIBLE OVER
THE NRN 2 TIERS OF COUNTIES. COLD ADVECTION WILL CONTINUE SUNDAY AS
H8 TEMPS FALL TO -8C WHICH WILL YIELD LAKE DELTA T/S AROUND 13C.
SHOULD SEE SOME LAKE CLOUDS WITH THIS SETUP ALONG WITH A CHANCE OF
SHOWERS...SOME OF WHICH MAY BE MIXED WITH SNOW OVER THE NRN CWA.
AS THE UPPER TROUGH MOVES AWAY SUNDAY NIGHT SKIES SHOULD CLEAR AND
TEMPS WILL FALL INTO THE 20S/LWR 30S. WIDESPREAD FROST IS EXPECTED
WITH FREEZING TEMPS OVER MUCH OF THE CWA. A FREEZE WARNING MAY BE
NEEDED SUNDAY NIGHT.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 334 AM EDT SAT MAY 11 2013
TYPICAL OF SPRING IN MICHIGAN OUR WARM THEN COLD THEN WARM AGAIN
WEATHER PATTERN WILL CONTINUE. MY ISSUE TODAY IS MOSTLY FOCUSED ON
WHAT HAPPENS TO THE FRONT THAT MOVES INTO THE AREA WEDNESDAY... DOES
IT STALL NEAR SOUTHWEST MICHIGAN PUTTING US BACK INTO A RAINY
PATTERN OR DOES IT SLIP FAR ENOUGH SOUTH TO DRY US OUT LATE THIS
COMING WEEK?
THE LARGE SCALE PATTERN CONTINUES TO FEATURE A HIGH AMPLITUDE UPPER
AIR PATTERN WITH CONSIDERABLE MERIDIONAL FLOW (WHY IT IS GETTING SO
COLD THIS WEEKEND). ALL OF THE OPERATIONAL MEDIUM RANGE MODELS
CONTINUE TO SUGGEST THIS PATTERN WILL FLATTEN OUT EARLY THIS COMING
WEEK. WE END UP WITH ONE OF THOSE EXTENDED EAST ASIAN JET FEATURES
BY MIDWEEK. TYPICALLY FOR SOUTHWEST MICHIGAN THAT MEANS WARMER THAN
NORMAL TEMPERATURES AND FREQUENT SHORTWAVES PRODUCING FREQUENT
PERIODS OF PRECIPITATION. ALL OF THIS HAS BEEN AND CONTINUES TO BE
THE MAIN ASPECT OF THE CHANGING UPPER AIR PATTERN. SO THE QUESTION
BECOMES... DOES THE FLATTER FLOW FORECAST BY THE ECMWF FROM
WEDNESDAY ON BECOME THE TRUE PATTERN OR WILL THE MORE AMPLIFIED
PATTERN OF THE GFS PREVAIL (THAT WOULD BE DRIER AND COOLER FOR
SOUTHWEST MICHIGAN)?
THERE ARE TWO CONCERNS OF MINE AS TOO WHY I QUESTION THE ECMWF THIS
TIME. FIRST IS THE SYSTEM MOVING ONTO THE WEST COAST CURRENTLY IS A
VERY DEEP TROUGH WITH A STRONG PACIFIC SYSTEM MOVING THROUGH THE
BASE OF THE TROUGH (JUST OFF THE OR/WA COAST). THE ECMWF FLATTENS
THIS WAVE AMAZINGLY FAST GIVEN ITS CURRENT AMPLITUDE. ALSO BOTH THE
ECMWF AND GFS SHOW A CLOSE UPPER HIGH DEVELOPING BY TUESDAY JUST
SOUTH OF GREENLAND. THAT THEN PERSISTS ON BOTH MODELS THROUGH THE
REST OF THE WEEK. OUR UPPER AIR FLOW WILL BE BLOCKED TO OUR EAST.
GIVEN THE BLOCKING TO THE EAST AND STRENGTH OF THE PACIFIC SYSTEM
MOVING ON SHORE (OUR WEDNESDAY SYSTEM) I WOULD HAVE TO FAVOR THE GFS
AT THIS POINT(MORE AMPLIFIED UPPER AIR PATTERN).
THE MORE AMPLIFIED PATTERN WOULD SUPPORT A STRONG COLD FRONT
WEDNESDAY EVENING WITH STRONGER THUNDERSTORMS BUT IT WOULD ALSO MEAN
A WARMER WEDNESDAY... THICKNESS VALUES AND 850 AND 925 MB TEMPS ARE
FORECAST TO BE AS WARM ENOUGH FOR LOWER TO MID 80S WEDNESDAY. SO I
HAVE TO IMAGINE EVEN WITH SOME FRONTAL CLOUDS AROUND MOST INLAND
AREAS SHOULD SEE HIGHS INTO THE LOWER 80S WEDNESDAY. WITH THAT MORE
AMPLIFIED PATTERN THE FRONT WOULD GO SOUTH OF MICHIGAN THURSDAY AND
IT WOULD COOL OFF SOME FOR THE REST OF THE WEEK.
IF THE ECMWF IS CORRECT... THE UPPER LOW OVER THE SW CONUS GETS
BOOTED EAST NORTHEAST TOWARD THE GREAT LAKES AND THAT BRING US A
STALLED FRONT WITH PERIODS OF SHOWERS AND THUNDERSTORMS WEDNESDAY
THROUGH FRIDAY (AND BEYOND).
FOR NOW I WILL SLIGHTLY FAVOR THE GFS AND KEEP POPS LOW WED THROUGH
FRIDAY. WE SHALL SEE HOW THIS PLAYS OUT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 748 AM EDT SAT MAY 11 2013
IFR CIGS WILL LIFT TO MVFR WITH SHOWER BY MIDDAY THEN IMPROVE TO
SOLID VFR AND IT MAY EVEN CLEAR FOR A FEW HOURS LATE THIS
AFTERNOON. HOWEVER IT WILL BE WINDY FROM MID AFTERNOON INTO THE
EVENING BEHIND THE COLD FRONT.
AS THE PREVIOUS SHIFT EXPECTED THE LOW CLOUDS PERSISTED THROUGH
THE NIGHT INTO THE MID MORNING HOURS. CEILING DID COME DOWN FROM
MVFR TO IFR ACROSS THE TAF SITES. WITHIN THE LAST HOUR MKG WENT
DOWN TO LIFR WITH FOG.
I WOULD EXPECT THE MIXING AHEAD OF THE COLD FRONT IN CONJUNCTION
WITH DAY TIME HEATING... THE CEILING WILL AT LEAST IMPROVE TO MVFR
BY LATE MORNING. AT 1140Z THERE REMAINS A SOLID BAND OF SHOWERS
JUST AHEAD OF THE COLD FRONT OVER WISCONSIN. THEY WILL CROSS THE
GRR AREA BTW 16Z AND 19Z AND THE LAN AREA BETWEEN 19Z AND 22Z.
THERE IS MARGINALLY ENOUGH INSTABILITY FOR A FEW THUNDERSTORMS BUT
THEY SHOULD BE TO WIDELY SCATTERED TO PUT IN THE TAF FORECAST.
STRONG SUBSIDENCE BEHIND THE COLD FRONT WILL CLEAR SKIES LATE THIS
AFTERNOON AND INCREASE THE WIND SPEED TO 15 TO 25 MPH WITH HIGHER
GUSTS. WRAP AROUND MOISTURE WILL BRING LOW CLOUDS BACK AFTER
MIDNIGHT BUT I DID NOT PUT THEM IN THE CURRENT TAF EXCEPT FOR MKG
TO KEEP THE TAFS AS SIMPLE AS POSSIBLE.
&&
.MARINE...
ISSUED AT 1106 AM EDT SAT MAY 11 2013
STRONGER GUSTS TO GALE FORCE ASSOCIATED WITH THE COLD FRONT ARE
SHOWN ON THE HRRR RUC. FSL RUC HAD GUSTS OVER 30 KNOTS. STABILITY
OF THE LAKE MAY BE AN ISSUE...LIMITING THIS RISK. SO FAR THE HRRR
IS VERIFIY WELL WITH THE UPSTREAM GUSTS. WENT AHEAD AND ISSUED A
GALE WARNING. THE WINDS WILL BE SHIFTING SHARPLY...ADDING TO THE
HAZARD. BY 00Z A LULL IN THE WINDS IS FORECASTED...SO THE GALE
WARNING IS OF A SHORTER DURATION. MAY NEED TO EXTEND IT AS THE
WINDS WILL PICK BACK UP BY DAYBREAK SUNDAY.
&&
.FIRE WEATHER...
ISSUED AT 334 AM EDT SAT MAY 11 2013
SHOWERS ARE EXPECTED MAINLY THIS AFTERNOON. COOLER TEMPERATURES WILL
FOLLOW SUNDAY WITH HIGHS IN THE 40S.
&&
.HYDROLOGY...
ISSUED AT 334 AM EDT SAT MAY 11 2013
RAINFALL LESS THAN A QUARTER INCH TODAY WILL HAVE A NEGLIGIBLE
EFFECT ON RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...93
SHORT TERM...93
LONG TERM...WDM
AVIATION...WDM
FIRE WEATHER...93
HYDROLOGY...93
MARINE...MJS
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1131 PM CDT FRI MAY 10 2013
.UPDATE...
ISSUED AT 905 PM CDT FRI MAY 10 2013
BACK EDGE OF LOW CLOUD DECK IS CURRENTLY NEAR A VERSAILLES...
BOONEVILLE...MOUNT PLEASANT IOWA LINE. EXTRAPOLATION SUGGESTS A
SE MOVEMENT OF 15-20KTS...A BIT FASTER THAN EARLIER EXPECTED.
SO...THIS UPDATE CLEAR SKIES A BIT MORE RAPIDLY...WITH A
CORRESPONDING DIP IN MIN TEMPS ESPECIALLY OVER THE NW HALF OF THE
CWA. WILL CARRY DRIZZLE FOR A FEW MORE HOURS IN OUR S
COUNTIES...PRIMARILY S AND SE OF STL.
TRUETT
&&
.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 328 PM CDT FRI MAY 10 2013
THE FIRST SHOT OF COOLER AIR HAS OVERSPREAD THE AREA WITH THE
ASSOCIATED COLD FRONT NOW ACROSS EXTREME SOUTHEAST MISSOURI AND
SOUTHERN ILLINOIS. EXTENSIVE STRATUS BLANKETS MUCH OF THE AREA AND
EXTENDS WELL NORTH INTO EASTERN IOWA AT MID AFTERNOON. THE MODELS
VARY ON HOW QUICKLY TO CLEAR THE LOW CLOUDS...AND I HAVE SIDED
WITH THE SLOWER RUC AND LOCAL WRF WITH SLOW CLEARING FROM NORTH TO
SOUTH TONIGHT...AND THE SOUTHEAST CWA NOT CLEARING UNTIL AFTER
DAYBREAK ON SATURDAY. A SERIES OF POWERFUL SHORT WAVES NOW ACROSS
MANITOBA AND SASKATCHEWAN WILL DIG SOUTHEASTWARD TONIGHT WITH A
CLOSED LOW EVOLVING. THIS UPPER LOW/TROF WILL CONTINUE TO DEEPEN
WITH A BROAD DEEP LONGWAVE TROF EVOLVING ACROSS THE EASTERN CONUS
BY SATURDAY NIGHT. INTIALLY IN THE PROCESS...THE DIGGING TROF
WILL DRIVE A COLD FRONT ACROSS THE AREA ON SATURDAY. THIS FRONT
WILL USHER A MORE POTENT BLAST OF CHILLY AIR INTO THE REGION ON
THE ORDER OF 2-3 STANDARD DEVIATIONS BELOW NORMAL. IT STILL LOOKS
LIKE THERE WILL BE A CHANCE OF SHOWERS AND EVEN SOME THUNDERSTORMS
FORMING ALONG THE FRONT AS IT MOVES QUICKLY SOUTHEASTWARD. THE
FORCING APPEARS TO BE LARGELY FRONTAL AND THIS SUGGESTS SCATTERED
COVERAGE. INSTABILITY WILL BE WEAK...PROBABLY OVERDONE ON THE NAM
OWING TO TOO HIGH SURFACE DEW POINTS...BUT STILL GREAT ENOUGH TO
SUPPORT A THUNDER THREAT. IT WILL BE A NARROW 1-2 HOUR WINDOW FOR
PRECIPITATION OCCURING WITH THE FRONT AND THEN GUSTY NW WINDS IT
ITS WAKE.
GLASS
.LONG TERM...(SATURDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 328 PM CDT FRI MAY 10 2013
THE DEEP LONGWAVE TROF WILL DOMINATE THE PATTERN AND CONTROL THE
SENSIBLE WEATHER SATURDAY NIGHT INTO EARLY MONDAY WITH A COOL
SURFACE HIGH PREVAILING. BELOW AVERAGE TEMPERATURES WILL BE THE
RULE AND SOME RECORDS COULD BE APPROACHED ON SUNDAY MORNING. THERE
COULD ALSO BE SOME PATCHY FROST WHERE LOWS DIP INTO THE MID 30S.
THE SURFACE HIGH MOVE ACROSS THE AREA ON SUNDAY AND GRADUALLY
RETREAT SOUTHEAST SUNDAY NIGHT INTO THE WESTERN TN VALLEY. THIS
SUGGESTS THAT THE COOLEST TEMPERATURES ON SUNDAY NIGHT AND MONDAY
MORNING WILL BE ACROSS THE EASTERN OZARKS AND SW ILLINOIS WHERE
LOWS IN THE MID-UPPER 30S AND PATCHY FROST WILL ONCE AGAIN BE
POSSIBLE. LOW LEVEL WAA WILL THEN COMMENCE ON MONDAY AND THIS
SHOULD LEAD TO A NICE REBOUND IN TEMPERATURES AS THE LOWER
TROPOSPHERIC FLOW BECOMES MORE SOUTHERLY.
SAY GOODBYE TO THE COOL...I THINK FOR GOOD...BY TUESDAY. THE LONGWAVE
TROF DEPARTS OFF THE EAST COAST AND HEIGHTS RISE ALOFT AS A SHORT
WAVE RIDGE BUILDS INTO THE MS VALLEY. STRONG WAA WILL PROGRESS AND
H85 TEMPS ARE FORECAST TO RISE ABOVE +18 DEGC ON ALL THE GUIDANCE...
SUPPORTING HIGHS WELL INTO THE 80S. MOISTURE AND CLOUDS WILL BEGIN
TO INCREASE LATE WEDNESDAY AS A NEW UPSTREAM TROF MOVES ACROSS THE
PLAINS AND EVENTUALLY INTO THE MS VALLEY BY THURSDAY. THE MODELS
DISAGREE ON WHETHER AN EAST-WEST FRONT WILL ALSO DROP INTO THE
AREA DURING THIS TIME...BUT THE PRESENCE OF THE UPPER TROF ALONE
SUPPORTS A CHANCE OF SHOWERS AND THUNDERSTORMS DURING THE LATER
PART OF THE WEEK.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1130 PM CDT FRI MAY 10 2013
CLOUDS SCATTERING OUT A BIT FASTER THAN ORIGINALLY THOUGHT...SO
ADJUSTED ACCORDINGLY. OTHERWISE...WINDS TO BECOME LIGHT AND VARIABLE.
SECONDARY FRONTAL BOUNDARY TO SLIDE THROUGH FORECAST AREA BY
MIDDAY TODAY...MOVING THROUGH KUIN BY 13Z...KCOU BY 14Z AND METRO
AREA BY 16Z. SOME WEAK INSTABILITY WITH BOUNDARY...BUT CHANCES OF
SHOWERS AND A FEW THUNDERSTORMS HARD TO PIN DOWN. SO JUST KEPT
VCNTY SHOWER MENTION/VFR CIGS FOR A FEW HOURS AFTER FRONTAL PASSAGE.
OTHERWISE...WINDS TO PICKUP BEHIND THE FRONT FROM THE NORTHWEST
WITH GUSTS NEAR 25KTS AT TIMES. THEN WINDS DIMINISH AFTER SUNSET
AND SKIES CLEAR OUT.
SPECIFICS FOR KSTL...CLOUDS SCATTERING FROM WEST TO EAST...SO
SHOULD STILL SCATTER OUT IN METRO AREA BY 09Z. OTHERWISE...WINDS TO
BECOME LIGHT AND VARIABLE. SECONDARY FRONTAL BOUNDARY TO SLIDE
THROUGH METRO AREA BY 16Z. SOME WEAK INSTABILITY WITH
BOUNDARY...BUT CHANCES OF SHOWERS AND A FEW THUNDERSTORMS HARD TO
PIN DOWN. SO JUST KEPT VCNTY SHOWER MENTION/VFR CIGS THROUGH 19Z.
OTHERWISE...WINDS TO PICKUP BEHIND THE FRONT FROM THE NORTHWEST
WITH GUSTS NEAR 25KTS AT TIMES. THEN WINDS DIMINISH AFTER 03Z
SUNDAY AND SKIES CLEAR OUT.
BYRD
&&
.CLIMATE...
ISSUED AT 328 PM CDT FRI MAY 10 2013
RECORD LOWS
5/125/13
ST LOUIS39 (1960)40 (1971)
COLUMBIA35 (1892)34 (1901)
QUINCY35 (1960)35 (1971)
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
150 PM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT MOVES SLOWLY THROUGH THE REGION OVERNIGHT. COOL HIGH
PRESSURE THEN BUILDS INTO THE REGION ON SUNDAY AND PERSISTS THROUGH
TUESDAY. BY WEDNESDAY...AS THE HIGH MOVES EAST...A WARMER SOUTHERLY
FLOW RETURNS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1025 AM SATURDAY...
MORNING PROXIMITY SOUNDINGS...MSAS...AND SPC MESOANALYSIS SHOWING
CURRENTLY THE GREATEST INSTABILITY FROM THE COASTAL PLAIN EASTWARD
WHERE THE DEEPEST MOISTURE RESIDES IN AND NEAR CENTRAL NORTH
CAROLINA. THERE ARE A FEW POSITIVE FACTORS FOR DEEP CONVECTIVE
DEVELOPMENT DURING THE AFTERNOON...INCLUDING WEAK SHORTWAVES MOVING
INTO THE AREA ON THE SOUTHWEST FLOW ALOFT...VERY MODEST COOLING
ALOFT ABOUT A DEGREE OR MAYBE TWO CELSIUS AS NOTED ON THE 12Z
UPPER-AIR ANALYSES...THE APPROACH OF A SURFACE TROUGH...AND THE
DIGGING UPPER TROUGH ON WATER VAPOR TO OUR NORTHWEST. 0-6KM SHEAR
INCREASES AS WELL...THOUGH MODEL SOUNDINGS NOTE THE INSTABILITY
SHOULD BE SOMEWHAT LIMITED WITH MIXED-LAYER CAPE FROM ABOUT 500 TO
1000J/KG. THE MID- AND UPPER-LEVEL JETS SHOULD BE LOCATED TO OUR
NORTHWEST THIS AFTERNOON AND LIKELY NOT COINCIDE WITH THE PERIOD OF
GREATEST HEATING...AND THE STRONGEST LOW-LEVEL WINDS SHOULD BE ALONG
AND OFF THE COAST. THE RUC AND THE NAM DIFFER ON THE LOCATION OF THE
GREATER MOISTURE AND INSTABILITY LATER THIS AFTERNOON...AS THE NAM
SHARPENS THE SURFACE TROUGH FARTHER EAST AND HAS A MORE PROGRESSIVE
PATTERN TO ADVANCING SHOWERS AND THUNDERSTORMS...WHILE THE RUC IS
SLOWER AND FARTHER WEST. HODOGRAPHS ARE FAIRLY STRAIGHT-LINE LATE
THIS AFTERNOON. OVERALL...THINK THE POTENTIAL FOR DEEP CONVECTION IS
GOOD AND HAVE MAINTAINED THE ORIENTATION OF CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASING TO LIKELY THIS AFTERNOON TOWARD THE TRIAD
AND ELSEWHERE ACROSS THE NORTHWEST PIEDMONT...SPREADING EAST AND
SOUTHEAST LATE THIS AFTERNOON INTO THE EVENING WITH AN ADVANCING
TROUGH AND COOL POOL PROCESSES FROM SMALL BANDS OF STORMS.
GIVEN THE HEATING OF THE DAY...INSTABILITY COULD BE A LITTLE GREATER
THAN FORECAST...ALTHOUGH LIMITED COOLING ALOFT SHOULD PRECLUDE
REALLY HIGH INSTABILITY. INCREASING SHEAR SHOULD HELP OVERCOME SOME
GENERALLY SLENDER CAPE ON THE LATEST BUFR SOUNDINGS AND MODEST WIND
FIELDS. SHOULD STORMS BECOME SEVERE...THE MAIN THREAT SHOULD BE
DOWNBURST WINDS...WITH A LESSER POTENTIAL FOR LARGE HAIL. NOT
ANTICIPATING A WIDESPREAD SEVERE WEATHER EVENT CURRENTLY...MORE
ISOLATED. THE BEST TIMING STILL APPEARS TO BE 2 OR 3 PM TO 9 PM.
INCREASED TEMPERATURES IN MOST AREAS A DEGREE OR TWO BASED ON THE
AMOUNT OF SUN AVAILABLE OVER CENTRAL NORTH CAROLINA AS OF THIS
WRITING...MORE IN LINE WITH MAV MOS AND BIAS-CORRECTED MOS GUIDANCE
GRIDDED DATA...AS WELL AS 1000-850MB THICKNESSES FORECAST BY THE
GFS. WITH THE INCREASE IN HEATING SHOULD BE REALIZED A FEW MORE WIND
GUSTS IN THE 20 TO 25 MPH RANGE AT TIMES. DRY COOL AIR ADVECTION
WILL REACH WESTERN PORTIONS OF THE FORECAST AREA BY DAYBREAK
SUNDAY...DROPPING TEMPERATURES INTO THE MID 50S WEST WHILE HOLDING
IN THE LOWER 60S EAST.
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 300 AM SATURDAY...
SHOWERS WILL BE IN THE PROCESS OF EXITING OFF THE COAST BY DAYBREAK
SUNDAY WITH INITIAL SURGE OF DRY AND COOLER AIR RESULTING IN NW TO
SE CLEARING SUNDAY MORNING. MEANWHILE...SLOW EASTWARD PROGRESSION OF
AMPLIFYING MID/UPPER LEVEL TROUGH WILL DELIVER A SECONDARY SURGE OF
DRY COOL AIR LATE IN THE DAY AS A MODIFIED CP AIRMASS BUILDS
SOUTHWARD REACHING THE GULF COAST AND SOUTHEAST US
SUNDAY NIGHT/MONDAY MORNING. HIGHS SUNDAY IN THE L-70S WEST TO
MID/UPPER 70S SOUTHEAST. CHILLY OVERNIGHT LOWS IN THE LOWER 40S TO
AROUND 50.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 245 AM SATURDAY...
SURFACE HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH EARLY NEXT
WEEK. THE MID/UPPER LEVEL TROUGH WILL STILL BE OVER THE AREA ON
MONDAY...BEFORE FINALLY MOVING EAST OF THE AREA MONDAY NIGHT.
THEREFORE...TEMPS ON MONDAY WILL BE WELL BELOW NORMAL...WITH HIGH
GENERALLY ONLY REACHING INTO THE MID/UPPER 60S TO POSSIBLY NEAR 70
DEGREES ACROSS THE FAR SOUTH. WITH THE SURFACE HIGH OVERHEAD MONDAY
NIGHT...GOOD RADIATIONAL COOLING CONDITIONS WILL SET UP...ALLOWING
OVERNIGHT LOWS TO FALL INTO THE LOW/MID 40S...WITH EVEN SOME UPPER
30S POSSIBLE IN THE USUALLY COOLER LOCALES.
THE SURFACE HIGH WILL SHIFT OFFSHORE LATE TUESDAY INTO WEDNESDAY AND
HEIGHTS WILL BEGIN TO RISE AS SHORTWAVE RIDGING BUILDS EAST OVER THE
AREA. THIS WILL ALLOW TEMPS TO MODERATE...ALTHOUGH ANOTHER DAY OF
BELOW NORMAL TEMPS IS EXPECTED ON TUESDAY (BUT SLIGHTLY WARMER THAN
MONDAY). BY WEDNESDAY...TEMPS SHOULD RETURN TO NEAR NORMAL...WITH
ABOVE NORMAL TEMPS EXPECTED BY THE END OF THE WEEK. THERE
CONTINUES TO BE DISAGREEMENT WITH RESPECT TO THE TIMING OF OUR NEXT
SYSTEM/BREAKDOWN OF THE MID LEVEL RIDGE. NEVERTHELESS...WILL SHOW
SLIGHT CHANCE DIURNAL POPS FOR FRIDAY AS SOUTHWESTERLY FLOW
INCREASES AND MODELS ARE HINTING AT A LEE TROUGH SETTING UP (HOWEVER
THE GFS BRINGS OUR NEXT FRONT IN ON FRIDAY...WHICH WOULD MEAN HIGHER
POP CHANCES...BUT THIS HAS BEEN CHANGING DAILY SO CONFIDENCE IS
LOW).
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 150 PM SATURDAY...
OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS...VFR CONDITIONS WILL
PREVAIL OVER CENTRAL NORTH CAROLINA. CONDITIONS COULD BECOME MVFR
FOR A TIME OVER THE NORTHWEST PIEDMONT VERY LATE THIS AFTERNOON AND
INTO THIS EVENING IN ANY AREA OF MORE STRATOFORM SHOWERS...BEHIND
ANY BANDS OF STRONGER SHOWERS OR STORMS. SKIES WILL GRADUALLY CLEAR
LATE TONIGHT AND INTO EARLY SUNDAY AS WINDS VEER WITH THE PASSAGE OF
A COLD FRONT. THE FRONT SHOULD BE A SLOW MOVER...AND ONLY EXIT
CENTRAL NORTH CAROLINA EAST OF THE INTERSTATE 95 CORRIDOR JUST
BEFORE SUNRISE. UNTIL THE ACTUAL FRONT PASSES...THERE APPEARS TO BE
ENOUGH MOISTURE AND LIFT FOR AVIATION INTERESTS TO BE AWARE OF THE
POTENTIAL FOR ISOLATED-TO-SCATTERED...LINGERING SHOWERS. DURING
SUNDAY MORNING...WITH MIXING...ANTICIPATE A FEW GUSTS DEVELOPING
INTO THE TEENS KNOTS FROM THE NORTHWEST.
BEYOND THE 18Z VALID TAF PERIOD...THERE IS A HIGH PROBABILITY OF VFR
CONDITIONS SUNDAY THROUGH TUESDAY. AS HIGH PRESSURE MOVES OFF TO THE
EAST AND A SOUTHERLY FLOW DEVELOPS OVER CENTRAL NORTH CAROLINA...THE
POTENTIAL FOR EARLY MORNING LOW CLOUDS INCREASES A LITTLE...
PARTICULARLY TOWARD KGSO WEDNESDAY. BASED ON CURRENT MODEL SOUNDINGS
FROM THE GFS...THERE IS A HIGHER POTENTIAL FOR SUB-VFR CONDITIONS
MAINLY IN LOW CLOUDS LATE WEDNESDAY NIGHT INTO THURSDAY MORNING.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DJF
NEAR TERM...CBL/DJF
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...DJF
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
125 PM EDT SAT MAY 11 2013
.SYNOPSIS...
CONVECTION WILL AFFECT THE AREA LATER TODAY AS A COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL MOVE ACROSS THE FORECAST
AREA AND OFFSHORE DURING SUNDAY. COOLER AND DRIER CONDITIONS WILL
AFFECT THE FORECAST AREA MONDAY THROUGH WEDNESDAY AS COOL
CANADIAN HIGH PRESSURE TRACKS ACROSS THE REGION RESULTING WITH
TEMPERATURES RUNNING 5 TO 10 DEGREES BELOW NORMAL. A WARMING TREND
IS EXPECTED AT THE END OF THE WEEK ONCE THE HIGH MOVES OFFSHORE
FROM THE CAROLINA COASTS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 120 PM SATURDAY...CAPE FEAR SEABREEZE CONVECTION ALREADY COME
AND GONE. THE REST OF THE FORECAST REMAINS RATHER PROBLEMATIC. SAT
IMAGERY CLEARLY SHOWS SUBSIDENCE ACRS MUCH OF THE REGION WITH EVEN
CU FIELDS FAILING TO DEVELOP DESPITE SURFACE TEMPS THAT WOULD
OTHERWISE BE SUPPORTIVE OF SUCH. THE CONVECTIVE DEBRIS STREAMING
ACROSS THE REGION MAKES IT DIFFICULT TO DISCERN THE LOCATION OF ANY
MEANINGFUL MID LEVEL POCKETS OF ENERGY. THAT SAID THE WRF NOW SHOWS
A PRONOUNCED VORT MIN (SUBSIDENCE) MOVING OVER THE REGION FROM THE
SOUTHWEST AT THIS TIME. ASSUMING THIS MODEL IS BETTER INITIALIZED
THEN THE NEXT FEW HOURS MAY BE RATHER QUIET. THE EXIT OF THE VORT
MIN FUNCTIONALLY THE SAME AS THE APPROACH OF A MAX SO ASCENT IN THE
MID LEVELS MAY BE REALIZED LATE AFTERNOON AND AN ATYPICALLY LATE
START TO STORM INITIATION STILL SEEMS POSSIBLE. FORECAST HAS NOT
CHANGED MUCH THE SENSE OF TIMING HAS JUST BEEN DELAYED A LITTLE.
AS OF 1030 AM SATURDAY...NOT THE MOST STRAIGHTFORWARD FORECAST IN
THE WORLD AT THIS POINT. SAT IMAGERY THIS MORNING SHOWS AMPLE BREAKS
IN THE CLOUDS AND MODERATE TO STRONG HEATING SHOULD GET UNDERWAY
TODAY. INSTABILITY NOT SO MUCH IN QUESTION WITH RESPECT TO
THUNDERSTORMS AS MUCH AS FORCING MECHANISM. CU FIELDS ALREADY
DEVELOPED OVER CAPE FEAR REGION AND HRRR SUGGESTS THAT ISO
CONVECTION MAY POP UP IN THIS VC BTW NOW AND 18Z...WHICH SEEMS
PLAUSIBLE ENOUGH. THERE SHOULD THEN BE A BREAK FOR A FEW HOURS AT
WHICH TIME ATTENTION TURNS TO OUR WEST. LATE AFTERNOON/EARLY EVENING
CONVECTION TO DEVELOP AND MOVE INTO THE REGION. LATEST SWODY1 FROM
SPC REDUCED SLIGHT RISK AREA CONSIDERABLY TAKING THE ENTIRE AREA
OUT. GIVEN THAT INSTABILITY LIKELY CAPPED AT 1000J PER KG AND SHEAR
MINIMAL THIS SEEMS FINE. WILL LEAVE FCST WORDING AS-IS WITH THE POSS
OF STRONG (SM HAIL AND GUSTY WINDS) BUT NOT SEVERE WORDING. LINE OF
STORMS MOVING IN FROM THE WEST LARGELY MISS SC COUNTIES ESP FURTHER
EAST INC GRAND STRAND AND MAY JUST MISS CAPE FEAR REGION TO THE N
AND W ALSO.
AS OF 630 AM SATURDAY...THE EVOLVING AND AMPLIFYING FULL LATITUDE
UPPER TROF OCCUPYING THE CENTRAL U.S. TODAY...AND THE EASTERN
THIRD OF THE U.S. BY DAYBREAK SUNDAY...WILL BE THE MAIN PLAYER
UPSTAIRS DURING THIS NEAR TERM PERIOD. FORTUNATELY THE SOUTHERN
STREAM CUT-OFF LOW OVER THE SW U.S. DOES NOT GET ABSORBED WITHIN
THE FLOW DURING THE EVOLUTION OF THIS UPPER TROF. WILL HAVE TO
CONTEND WITH ROTATING MID LEVEL VORTICIES/IMPULSES TRACKING ALONG
THE EAST SIDE OF THIS UPPER TROF AXIS. MODELS INDICATE THE
POSSIBILITY OF 1 TRACKING ACROSS THE CENTRAL CAROLINAS THIS
AFTERNOON AND EVENING...AIDING UPWARD FORCING IE. UVVS. DURING
THIS TIME PERIOD...A LEE SIDE...PRE-FRONTAL TROF...WILL HAVE
DEVELOPED ACROSS THE CENTRAL CAROLINAS AND SLOWLY TRACK TOWARDS
THE COAST THIS AFTERNOON AND EVENING. THE TIMING OF THIS UPPER
FEATURE AND ITS INTERACTION WITH THE SFC TROF COULD BE THE
DIFFERENCE FOR STRONG TO POSSIBLY SEVERE THUNDERSTORM ACTIVITY.
MODEL TIMING DIFFERENCES CONTINUE WITH THIS POSSIBLE INCREASED
POTENTIAL...IF IT OCCURS AT ALL. AT THIS POINT...WILL HIGHLIGHT
THE ISOLATED SEVERE IN THE HWO BUT MAINLY FOR THE INLAND COUNTIES.
SPC INDICATES LARGE HAIL AND DAMAGING WIND GUSTS THE PRIMARY
SEVERE THREATS. THE SFC BASED STABLE MARINE LAYER WILL BE CONFINED
BASICALLY TO THE COAST DUE TO THE STRONG SW-W WINDS JUST OFF THE
DECK PREVENTING ANY INLAND PROGRESSION OF THE SEA BREEZE.
SREF PROBS OF MEASURED PCPN CONTINUES THE GENERAL TREND FROM
YESTERDAY HIGHLIGHTING SPLIT PCPN MAXIMAS ASSOCIATED WITH THIS
CONVECTION. MEANING...THE ILM CWA REMAINS IN THE MIDDLE OR WITHIN
THE LOWEST PROBABILITY FOR MEASURED PCPN...IE. DRIER. WITH ALL THIS
SAID...HAVE SLIGHTLY LOWERED POPS TO 40 TO 60 PERCENT DURING THE
PEAK OF THIS AFTERNOON/EARLY EVENING CONVECTION. NAM AND GFS MOS
GUIDANCE REMAIN SIMILAR TO MAXES TODAY WITH MID 80S INLAND...UPPER
70S ALONG THE IMMEDIATE COAST PRIOR TO THE PINNED SEA BREEZE
DEVELOPMENT. HAVE STAYED CLOSER TO THE HIER SIDE OF MODEL MOS
GUIDANCE FOR TONIGHTS LOWS...DUE TO A SLOWER PROGRESSION OF THE
CFP ACROSS THE FA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...THE COLD FRONT WILL BE JUST INLAND AT THE
BEGINNING OF THE PERIOD AND WILL QUICKLY MOVE OFFSHORE DURING THE
MORNING HOURS. MAINTAINED THE INHERITED POPS WHICH SHOW GOOD
CHANCE ALONG THE COAST WITH MINIMUM VALUES INLAND. BY SUNDAY
AFTERNOON THE FRONT IS WELL OFFSHORE AND HAVE REMOVED POPS FROM
THE 0000-0600 UTC TIME FRAME. A TEMPERATURE FORECAST FROM THIS
POINT ON AS A SECONDARY SHORTWAVE THAT MOVES ACROSS MONDAY
AFTERNOON BRINGS ALONG THE BEST COLD AIR ADVECTION. THE MID
AFTERNOON ARRIVAL OF THE COLD AIR WILL ALLOW TEMPERATURES TO RISE
AT OR JUST ABOVE 70 MONDAY. TUESDAY MORNING LOWS REMAIN IN THE 40S
MODERATED BY A FEW KNOTS OF WIND REMAINING IN THE BOUNDARY LAYER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...THE MID LEVEL PATTERN WILL QUICKLY CHANGE
FROM EAST COAST TROUGHING TO A QUASI ZONAL FLOW AS WEAK
SHORTWAVES WILL MOVE QUICKLY ACROSS THE CONUS. WPC GRAPHICS ARE
DOMINATED BY A PREFERENCE FOR THE ECMWF ENSEMBLE MEAN. ALL IS
QUIET UNTIL FRIDAY REGARDING POPS WHEN A WEAK SHORTWAVE WILL ALLOW
A PIEDMONT TROUGH TO DEVELOP AND MAINTAINED THE SLIGHT CHANCE
POPS. FORCING IS NEGLIGIBLE AS WOULD BE EXPECTED WITH THE LACK OF
MID LEVEL AMPLITUDE AND THIS SEEMS REASONABLE. TEMPERATURE TRENDS
REMAIN IN PLACE WITH A QUICK RECOVERY FROM BELOW NORMAL VALUES
EARLY TO SLIGHTLY ABOVE NUMBERS LATE.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 18Z...LOOKS LIKE SOME SEA BREEZE ACTIVITY WILL OCCUR FOR THE
FIRST COUPLE OF HOURS OF TAF TIME...MAINLY OVER NORTH CAROLINA.
THEIR LOCATION AND MOTION WILL KEEP THEM AWAY FROM ILM. THUNDER WILL
ISOLATED. THIS EVENING...A COLD FRONT APPROACHES FROM THE
WEST...WITH SCATTERED TO POSSIBLY NUMEROUS CONVECTION OUT AHEAD.
WENT WITH INTERMITTENT THUNDER AT THE INLAND TERMINALS...BUT THIS
MAY BE OVERDONE. CONVECTION REACHES THE COAST 2-3 HOURS LATER. THE
CONVECTION WILL LIKELY BE WANING FOR DIURNAL REASONS. LOOK FOR A
WIND SHIFT TO THE WEST...THEN NORTHWEST AS THE COLD FRONT PUSHES
THROUGH. CONDITIONS WILL IMPROVE TO VFR FIRST AT THE INLAND
TERMINALS...WITH MVFR/IFR CEILINGS HOLDING ON NEAR THE COAST THROUGH
DAYBREAK...BECOMING VFR WITH A NORTHWEST WIND BY MID MORNING.
EXTENDED OUTLOOK...VFR CONDITIONS SUNDAY AFTERNOON THRU WEDNESDAY
DUE TO COOL CANADIAN HIGH PRESSURE. MORNING FOG POSSIBLE THURSDAY.
&&
.MARINE...
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM SATURDAY...LITTLE TO NO CHANGES IN FORECAST THINKING
AT THIS TIME. SW GRADIENT WINDS TO INC SLIGHTLY POSSIBLY BOOSTING
SEAS HIGH ENOUGH TO WARRANT SCEC OVER NRN ZONE OR TWO.
AS OF 630 AM SATURDAY...A PRE-FRONTAL TROF WILL DEVELOP ACROSS THE
EAST CENTRAL CAROLINAS TODAY...AND MESH WITH THE APPROACHING COLD
FRONT TONIGHT. THIS FRONT WILL JUST REACH THE CAROLINA COASTS
AROUND DAYBREAK SUNDAY. THE SFC PRESSURE PATTERN AND TIGHTENING
GRADIENT AHEAD OF THE INLAND TROF WILL PRODUCE A SOLID SSW-SW WIND
AT 15 TO 20 KT...WITH A FEW GUSTS UP TO 25 KT POSSIBLE ACROSS THE
ILM NC WATERS. SIGNIFICANT SEAS WILL PRIMARILY BE A FUNCTION OF
THE 4 TO 6 SECOND PERIOD LOCALLY PRODUCED WIND DRIVEN WAVES.
THEREFORE...EXPECT A QUICK BUILDING OF THE SEAS BY THIS AFTERNOON
WITH 3 TO 5 FT ILM NC WATERS AND 3 TO 4 FT FOR THE ILM SC WATERS.
THE PROGGED AFTERNOON AND EVENING WIND AND SEAS COMBO FORECAST
WILL EXCEED SMALL CRAFT EXERCISE CAUTION THRESHOLDS FOR THE ILM NC
WATERS. WILL ISSUE THE SCEC FOR THE HOURS BETWEEN NOON TODAY
THROUGH 6 AM SUNDAY. A PINNED SEA BREEZE COULD PRODUCE A SLIGHT
BACKING OF THE WINDS NEAR SHORE TO S-SSW THIS AFTERNOON AND EARLY
EVENING. THE RELATIVELY COOLER NEAR SHORE WATERS...60S SSTS...WILL
HAVE A TREND TO WEAKEN THUNDERSTORMS THAT MOVE OFF THE MAINLAND
LATER TODAY. WILL HIGHLIGHT IN THE HWO FOR THE THREAT FOR 25 TO 35
KT WIND GUSTS FROM CONVECTION MOVING OFF THE MAINLAND.
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...A COLD FRONT WILL CROSS THE WATERS EARLY
SUNDAY WITH WINDS SHIFTING FROM SOUTHWEST TO NORTH. WIND SPEEDS WILL
REMAIN TEPID WITH THE WIND SHIFT...ON THE LOWE SIDE OF 10-15 KNOTS
UNTIL MONDAY WHEN A SECONDARY SHORTWAVE WITH DECENT COLD AIR
ADVECTION ARRIVES. SPEEDS AT THIS TIME WILL INCREASE BRIEFLY TO
15-20 KNOTS. BY TUESDAY MORNING...SPEEDS WILL LIKELY DROP A COUPLE
OF KNOTS. SIGNIFICANT SEAS WILL HOVER IN A 2-4 FOOT RANGE WITH THE
HIGHER VALUES MAINLY CONFINED TO THE OUTER WATERS.
.LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...HIGH PRESSURE WILL MOVE QUICKLY FROM THE
APPALACHIANS TO OFF THE SOUTHEAST COAST BY THE END OF THE PERIOD.
NORTHERLY WINDS WILL QUICKLY BACK TO A WEAK...LESS THAN TEN KNOTS...
SOUTHWESTERLY DIRECTION BY MIDDAY WEDNESDAY. THE DEVELOPMENT OF A
PIEDMONT TROUGH EARLY THURSDAY WHICH IS MORE INDICATIVE OF A MID
SUMMER PATTERN WILL INCREASE THE GRADIENT BACK TO THE HIGHER END OF
A 10-15 KNOT RANGE. SEAS WILL BE THE HIGHEST EARLY WITH SOME FOUR
FOOTERS ACROSS THE OUTER WATERS. HEIGHTS REALLY DIMINISH WEDNESDAY
BEFORE INCREASING ONCE AGAIN EARLY THURSDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...MBB/DCH
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...MBB/DL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1025 AM EDT SAT MAY 11 2013
.SYNOPSIS...
CONVECTION WILL AFFECT THE AREA LATER TODAY AS A COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL MOVE ACROSS THE FORECAST
AREA AND OFFSHORE DURING SUNDAY. COOLER AND DRIER CONDITIONS WILL
AFFECT THE FORECAST AREA MONDAY THROUGH WEDNESDAY AS COOL
CANADIAN HIGH PRESSURE TRACKS ACROSS THE REGION RESULTING WITH
TEMPERATURES RUNNING 5 TO 10 DEGREES BELOW NORMAL. A WARMING TREND
IS EXPECTED AT THE END OF THE WEEK ONCE THE HIGH MOVES OFFSHORE
FROM THE CAROLINA COASTS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM SATURDAY...NOT THE MOST STRAIGHTFORWARD FORECAST IN
THE WORLD AT THIS POINT. SAT IMAGERY THIS MORNING SHOWS AMPLE BREAKS
IN THE CLOUDS AND MODERATE TO STRONG HEATING SHOULD GET UNDERWAY
TODAY. INSTABILITY NOT SO MUCH IN QUESTION WITH RESPECT TO
THUNDERSTORMS AS MUCH AS FORCING MECHANISM. CU FIELDS ALREADY
DEVELOPED OVER CAPE FEAR REGION AND HRRR SUGGESTS THAT ISO
CONVECTION MAY POP UP IN THIS VC BTW NOW AND 18Z...WHICH SEEMS
PLAUSIBLE ENOUGH. THERE SHOULD THEN BE A BREAK FOR A FEW HOURS AT
WHICH TIME ATTENTION TURNS TO OUR WEST. LATE AFTERNOON/EARLY EVENING
CONVECTION TO DEVELOP AND MOVE INTO THE REGION. LATEST SWODY1 FROM
SPC REDUCED SLIGHT RISK AREA CONSIDERABLY TAKING THE ENTIRE AREA
OUT. GIVEN THAT INSTABILITY LIKELY CAPPED AT 1000J PER KG AND SHEAR
MINIMAL THIS SEEMS FINE. WILL LEAVE FCST WORDING AS-IS WITH THE POSS
OF STRONG (SM HAIL AND GUSTY WINDS) BUT NOT SEVERE WORDING. LINE OF
STORMS MOVING IN FROM THE WEST LARGELY MISS SC COUNTIES ESP FURTHER
EAST INC GRAND STRAND AND MAY JUST MISS CAPE FEAR REGION TO THE N
AND W ALSO.
AS OF 630 AM SATURDAY...THE EVOLVING AND AMPLIFYING FULL LATITUDE
UPPER TROF OCCUPYING THE CENTRAL U.S. TODAY...AND THE EASTERN
THIRD OF THE U.S. BY DAYBREAK SUNDAY...WILL BE THE MAIN PLAYER
UPSTAIRS DURING THIS NEAR TERM PERIOD. FORTUNATELY THE SOUTHERN
STREAM CUT-OFF LOW OVER THE SW U.S. DOES NOT GET ABSORBED WITHIN
THE FLOW DURING THE EVOLUTION OF THIS UPPER TROF. WILL HAVE TO
CONTEND WITH ROTATING MID LEVEL VORTICIES/IMPULSES TRACKING ALONG
THE EAST SIDE OF THIS UPPER TROF AXIS. MODELS INDICATE THE
POSSIBILITY OF 1 TRACKING ACROSS THE CENTRAL CAROLINAS THIS
AFTERNOON AND EVENING...AIDING UPWARD FORCING IE. UVVS. DURING
THIS TIME PERIOD...A LEE SIDE...PRE-FRONTAL TROF...WILL HAVE
DEVELOPED ACROSS THE CENTRAL CAROLINAS AND SLOWLY TRACK TOWARDS
THE COAST THIS AFTERNOON AND EVENING. THE TIMING OF THIS UPPER
FEATURE AND ITS INTERACTION WITH THE SFC TROF COULD BE THE
DIFFERENCE FOR STRONG TO POSSIBLY SEVERE THUNDERSTORM ACTIVITY.
MODEL TIMING DIFFERENCES CONTINUE WITH THIS POSSIBLE INCREASED
POTENTIAL...IF IT OCCURS AT ALL. AT THIS POINT...WILL HIGHLIGHT
THE ISOLATED SEVERE IN THE HWO BUT MAINLY FOR THE INLAND COUNTIES.
SPC INDICATES LARGE HAIL AND DAMAGING WIND GUSTS THE PRIMARY
SEVERE THREATS. THE SFC BASED STABLE MARINE LAYER WILL BE CONFINED
BASICALLY TO THE COAST DUE TO THE STRONG SW-W WINDS JUST OFF THE
DECK PREVENTING ANY INLAND PROGRESSION OF THE SEA BREEZE.
SREF PROBS OF MEASURED PCPN CONTINUES THE GENERAL TREND FROM
YESTERDAY HIGHLIGHTING SPLIT PCPN MAXIMAS ASSOCIATED WITH THIS
CONVECTION. MEANING...THE ILM CWA REMAINS IN THE MIDDLE OR WITHIN
THE LOWEST PROBABILITY FOR MEASURED PCPN...IE. DRIER. WITH ALL THIS
SAID...HAVE SLIGHTLY LOWERED POPS TO 40 TO 60 PERCENT DURING THE
PEAK OF THIS AFTERNOON/EARLY EVENING CONVECTION. NAM AND GFS MOS
GUIDANCE REMAIN SIMILAR TO MAXES TODAY WITH MID 80S INLAND...UPPER
70S ALONG THE IMMEDIATE COAST PRIOR TO THE PINNED SEA BREEZE
DEVELOPMENT. HAVE STAYED CLOSER TO THE HIER SIDE OF MODEL MOS
GUIDANCE FOR TONIGHTS LOWS...DUE TO A SLOWER PROGRESSION OF THE
CFP ACROSS THE FA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...THE COLD FRONT WILL BE JUST INLAND AT THE
BEGINNING OF THE PERIOD AND WILL QUICKLY MOVE OFFSHORE DURING THE
MORNING HOURS. MAINTAINED THE INHERITED POPS WHICH SHOW GOOD
CHANCE ALONG THE COAST WITH MINIMUM VALUES INLAND. BY SUNDAY
AFTERNOON THE FRONT IS WELL OFFSHORE AND HAVE REMOVED POPS FROM
THE 0000-0600 UTC TIME FRAME. A TEMPERATURE FORECAST FROM THIS
POINT ON AS A SECONDARY SHORTWAVE THAT MOVES ACROSS MONDAY
AFTERNOON BRINGS ALONG THE BEST COLD AIR ADVECTION. THE MID
AFTERNOON ARRIVAL OF THE COLD AIR WILL ALLOW TEMPERATURES TO RISE
AT OR JUST ABOVE 70 MONDAY. TUESDAY MORNING LOWS REMAIN IN THE 40S
MODERATED BY A FEW KNOTS OF WIND REMAINING IN THE BOUNDARY LAYER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...THE MID LEVEL PATTERN WILL QUICKLY CHANGE
FROM EAST COAST TROUGHING TO A QUASI ZONAL FLOW AS WEAK
SHORTWAVES WILL MOVE QUICKLY ACROSS THE CONUS. WPC GRAPHICS ARE
DOMINATED BY A PREFERENCE FOR THE ECMWF ENSEMBLE MEAN. ALL IS
QUIET UNTIL FRIDAY REGARDING POPS WHEN A WEAK SHORTWAVE WILL ALLOW
A PIEDMONT TROUGH TO DEVELOP AND MAINTAINED THE SLIGHT CHANCE
POPS. FORCING IS NEGLIGIBLE AS WOULD BE EXPECTED WITH THE LACK OF
MID LEVEL AMPLITUDE AND THIS SEEMS REASONABLE. TEMPERATURE TRENDS
REMAIN IN PLACE WITH A QUICK RECOVERY FROM BELOW NORMAL VALUES
EARLY TO SLIGHTLY ABOVE NUMBERS LATE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CONFIDENCE ONLY MODERATE THIS MORNING AS MODELS ARE NOT
IN AGREEMENT. WILL LEAN HEAVILY ON THE HRRR MODEL IN THE NEAR
TERM...WITH SCATTERED TO BROKEN CONVECTION DEVELOPING ALONG THE
COAST AND MOVING INTO THE MYRTLES ABOUT AN HOUR AFTER TAF TIME. ILM
STANDS THE BEST CHANCE FOR CONVECTION...WITH A RUMBLE OF THUNDER
POSSIBLE AFTER 16Z. VISIBILITIES WILL BE MVFR IN THE
SHOWERS...HOWEVER BRIEF PERIODS OF IFR ARE EXPECTED...LIKELY LASTING
15 MINUTES OR LESS AT A TIME. LOOK FOR A LULL IN THE ACTION...WITH
MORE CONVECTION FIRING MID TO LATE AFTERNOON OVER THE WESTERN
PORTION OF THE CWA IN ADVANCE OF A COLD FRONT. THIS CONVECTION IS
EXPECTED TO CONTINUE INTO THE EVENING HOURS...REACHING THE COAST BY
02-03Z.
EXTENDED OUTLOOK...LOW TO MODERATE CHANCE FOR CONVECTION DURING THE
PRE-DAWN SUNDAY HRS THROUGH MIDDAY SUNDAY DUE TO THE PASSAGE OF THE
COLD FRONT. MAY OBSERVE BRIEF IFR CONDITIONS. VFR CONDITIONS SUNDAY
AFTERNOON THRU WEDNESDAY DUE TO COOL CANADIAN HIGH PRESSURE.
&&
.MARINE...
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM SATURDAY...LITTLE TO NO CHANGES IN FORECAST THINKING
AT THIS TIME. SW GRADIENT WINDS TO INC SLIGHTLY POSSIBLY BOOSTING
SEAS HIGH ENOUGH TO WARRANT SCEC OVER NRN ZONE OR TWO.
AS OF 630 AM SATURDAY...A PRE-FRONTAL TROF WILL DEVELOP ACROSS THE
EAST CENTRAL CAROLINAS TODAY...AND MESH WITH THE APPROACHING COLD
FRONT TONIGHT. THIS FRONT WILL JUST REACH THE CAROLINA COASTS
AROUND DAYBREAK SUNDAY. THE SFC PRESSURE PATTERN AND TIGHTENING
GRADIENT AHEAD OF THE INLAND TROF WILL PRODUCE A SOLID SSW-SW WIND
AT 15 TO 20 KT...WITH A FEW GUSTS UP TO 25 KT POSSIBLE ACROSS THE
ILM NC WATERS. SIGNIFICANT SEAS WILL PRIMARILY BE A FUNCTION OF
THE 4 TO 6 SECOND PERIOD LOCALLY PRODUCED WIND DRIVEN WAVES.
THEREFORE...EXPECT A QUICK BUILDING OF THE SEAS BY THIS AFTERNOON
WITH 3 TO 5 FT ILM NC WATERS AND 3 TO 4 FT FOR THE ILM SC WATERS.
THE PROGGED AFTERNOON AND EVENING WIND AND SEAS COMBO FORECAST
WILL EXCEED SMALL CRAFT EXERCISE CAUTION THRESHOLDS FOR THE ILM NC
WATERS. WILL ISSUE THE SCEC FOR THE HOURS BETWEEN NOON TODAY
THROUGH 6 AM SUNDAY. A PINNED SEA BREEZE COULD PRODUCE A SLIGHT
BACKING OF THE WINDS NEAR SHORE TO S-SSW THIS AFTERNOON AND EARLY
EVENING. THE RELATIVELY COOLER NEAR SHORE WATERS...60S SSTS...WILL
HAVE A TREND TO WEAKEN THUNDERSTORMS THAT MOVE OFF THE MAINLAND
LATER TODAY. WILL HIGHLIGHT IN THE HWO FOR THE THREAT FOR 25 TO 35
KT WIND GUSTS FROM CONVECTION MOVING OFF THE MAINLAND.
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...A COLD FRONT WILL CROSS THE WATERS EARLY
SUNDAY WITH WINDS SHIFTING FROM SOUTHWEST TO NORTH. WIND SPEEDS WILL
REMAIN TEPID WITH THE WIND SHIFT...ON THE LOWE SIDE OF 10-15 KNOTS
UNTIL MONDAY WHEN A SECONDARY SHORTWAVE WITH DECENT COLD AIR
ADVECTION ARRIVES. SPEEDS AT THIS TIME WILL INCREASE BRIEFLY TO
15-20 KNOTS. BY TUESDAY MORNING...SPEEDS WILL LIKELY DROP A COUPLE
OF KNOTS. SIGNIFICANT SEAS WILL HOVER IN A 2-4 FOOT RANGE WITH THE
HIGHER VALUES MAINLY CONFINED TO THE OUTER WATERS.
.LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...HIGH PRESSURE WILL MOVE QUICKLY FROM THE
APPALACHIANS TO OFF THE SOUTHEAST COAST BY THE END OF THE PERIOD.
NORTHERLY WINDS WILL QUICKLY BACK TO A WEAK...LESS THAN TEN KNOTS...
SOUTHWESTERLY DIRECTION BY MIDDAY WEDNESDAY. THE DEVELOPMENT OF A
PIEDMONT TROUGH EARLY THURSDAY WHICH IS MORE INDICATIVE OF A MID
SUMMER PATTERN WILL INCREASE THE GRADIENT BACK TO THE HIGHER END OF
A 10-15 KNOT RANGE. SEAS WILL BE THE HIGHEST EARLY WITH SOME FOUR
FOOTERS ACROSS THE OUTER WATERS. HEIGHTS REALLY DIMINISH WEDNESDAY
BEFORE INCREASING ONCE AGAIN EARLY THURSDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...MBB/DCH
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DL
MARINE...
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
645 AM EDT SAT MAY 11 2013
.SYNOPSIS...
CONVECTION WILL AFFECT THE AREA LATER TODAY AS A COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL MOVE ACROSS THE FORECAST
AREA AND OFFSHORE DURING SUNDAY. COOLER AND DRIER CONDITIONS WILL
AFFECT THE FORECAST AREA MONDAY THROUGH WEDNESDAY AS COOL
CANADIAN HIGH PRESSURE TRACKS ACROSS THE REGION RESULTING WITH
TEMPERATURES RUNNING 5 TO 10 DEGREES BELOW NORMAL. A WARMING TREND
IS EXPECTED AT THE END OF THE WEEK ONCE THE HIGH MOVES OFFSHORE
FROM THE CAROLINA COASTS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...THE EVOLVING AND AMPLIFYING FULL LATITUDE
UPPER TROF OCCUPYING THE CENTRAL U.S. TODAY...AND THE EASTERN
THIRD OF THE U.S. BY DAYBREAK SUNDAY...WILL BE THE MAIN PLAYER
UPSTAIRS DURING THIS NEAR TERM PERIOD. FORTUNATELY THE SOUTHERN
STREAM CUT-OFF LOW OVER THE SW U.S. DOES NOT GET ABSORBED WITHIN
THE FLOW DURING THE EVOLUTION OF THIS UPPER TROF. WILL HAVE TO
CONTEND WITH ROTATING MID LEVEL VORTICIES/IMPULSES TRACKING ALONG
THE EAST SIDE OF THIS UPPER TROF AXIS. MODELS INDICATE THE
POSSIBILITY OF 1 TRACKING ACROSS THE CENTRAL CAROLINAS THIS
AFTERNOON AND EVENING...AIDING UPWARD FORCING IE. UVVS. DURING
THIS TIME PERIOD...A LEE SIDE...PRE-FRONTAL TROF...WILL HAVE
DEVELOPED ACROSS THE CENTRAL CAROLINAS AND SLOWLY TRACK TOWARDS
THE COAST THIS AFTERNOON AND EVENING. THE TIMING OF THIS UPPER
FEATURE AND ITS INTERACTION WITH THE SFC TROF COULD BE THE
DIFFERENCE FOR STRONG TO POSSIBLY SEVERE THUNDERSTORM ACTIVITY.
MODEL TIMING DIFFERENCES CONTINUE WITH THIS POSSIBLE INCREASED
POTENTIAL...IF IT OCCURS AT ALL. AT THIS POINT...WILL HIGHLIGHT
THE ISOLATED SEVERE IN THE HWO BUT MAINLY FOR THE INLAND COUNTIES.
SPC INDICATES LARGE HAIL AND DAMAGING WIND GUSTS THE PRIMARY
SEVERE THREATS. THE SFC BASED STABLE MARINE LAYER WILL BE CONFINED
BASICALLY TO THE COAST DUE TO THE STRONG SW-W WINDS JUST OFF THE
DECK PREVENTING ANY INLAND PROGRESSION OF THE SEA BREEZE.
SREF PROBS OF MEASURED PCPN CONTINUES THE GENERAL TREND FROM
YESTERDAY HIGHLIGHTING SPLIT PCPN MAXIMAS ASSOCIATED WITH THIS
CONVECTION. MEANING...THE ILM CWA REMAINS IN THE MIDDLE OR WITHIN
THE LOWEST PROBABILITY FOR MEASURED PCPN...IE. DRIER. WITH ALL THIS
SAID...HAVE SLIGHTLY LOWERED POPS TO 40 TO 60 PERCENT DURING THE
PEAK OF THIS AFTERNOON/EARLY EVENING CONVECTION. NAM AND GFS MOS
GUIDANCE REMAIN SIMILAR TO MAXES TODAY WITH MID 80S INLAND...UPPER
70S ALONG THE IMMEDIATE COAST PRIOR TO THE PINNED SEA BREEZE
DEVELOPMENT. HAVE STAYED CLOSER TO THE HIER SIDE OF MODEL MOS
GUIDANCE FOR TONIGHTS LOWS...DUE TO A SLOWER PROGRESSION OF THE
CFP ACROSS THE FA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...THE COLD FRONT WILL BE JUST INLAND AT THE
BEGINNING OF THE PERIOD AND WILL QUICKLY MOVE OFFSHORE DURING THE
MORNING HOURS. MAINTAINED THE INHERITED POPS WHICH SHOW GOOD
CHANCE ALONG THE COAST WITH MINIMUM VALUES INLAND. BY SUNDAY
AFTERNOON THE FRONT IS WELL OFFSHORE AND HAVE REMOVED POPS FROM
THE 0000-0600 UTC TIME FRAME. A TEMPERATURE FORECAST FROM THIS
POINT ON AS A SECONDARY SHORTWAVE THAT MOVES ACROSS MONDAY
AFTERNOON BRINGS ALONG THE BEST COLD AIR ADVECTION. THE MID
AFTERNOON ARRIVAL OF THE COLD AIR WILL ALLOW TEMPERATURES TO RISE
AT OR JUST ABOVE 70 MONDAY. TUESDAY MORNING LOWS REMAIN IN THE 40S
MODERATED BY A FEW KNOTS OF WIND REMAINING IN THE BOUNDARY LAYER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...THE MID LEVEL PATTERN WILL QUICKLY CHANGE
FROM EAST COAST TROUGHING TO A QUASI ZONAL FLOW AS WEAK
SHORTWAVES WILL MOVE QUICKLY ACROSS THE CONUS. WPC GRAPHICS ARE
DOMINATED BY A PREFERENCE FOR THE ECMWF ENSEMBLE MEAN. ALL IS
QUIET UNTIL FRIDAY REGARDING POPS WHEN A WEAK SHORTWAVE WILL ALLOW
A PIEDMONT TROUGH TO DEVELOP AND MAINTAINED THE SLIGHT CHANCE
POPS. FORCING IS NEGLIGIBLE AS WOULD BE EXPECTED WITH THE LACK OF
MID LEVEL AMPLITUDE AND THIS SEEMS REASONABLE. TEMPERATURE TRENDS
REMAIN IN PLACE WITH A QUICK RECOVERY FROM BELOW NORMAL VALUES
EARLY TO SLIGHTLY ABOVE NUMBERS LATE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...CONFIDENCE ONLY MODERATE THIS MORNING AS MODELS ARE NOT
IN AGREEMENT. WILL LEAN HEAVILY ON THE HRRR MODEL IN THE NEAR
TERM...WITH SCATTERED TO BROKEN CONVECTION DEVELOPING ALONG THE
COAST AND MOVING INTO THE MYRTLES ABOUT AN HOUR AFTER TAF TIME. ILM
STANDS THE BEST CHANCE FOR CONVECTION...WITH A RUMBLE OF THUNDER
POSSIBLE AFTER 16Z. VISIBILITIES WILL BE MVFR IN THE
SHOWERS...HOWEVER BRIEF PERIODS OF IFR ARE EXPECTED...LIKELY LASTING
15 MINUTES OR LESS AT A TIME. LOOK FOR A LULL IN THE ACTION...WITH
MORE CONVECTION FIRING MID TO LATE AFTERNOON OVER THE WESTERN
PORTION OF THE CWA IN ADVANCE OF A COLD FRONT. THIS CONVECTION IS
EXPECTED TO CONTINUE INTO THE EVENING HOURS...REACHING THE COAST BY
02-03Z.
EXTENDED OUTLOOK...LOW TO MODERATE CHANCE FOR CONVECTION DURING THE
PRE-DAWN SUNDAY HRS THROUGH MIDDAY SUNDAY DUE TO THE PASSAGE OF THE
COLD FRONT. MAY OBSERVE BRIEF IFR CONDITIONS. VFR CONDITIONS SUNDAY
AFTERNOON THRU WEDNESDAY DUE TO COOL CANADIAN HIGH PRESSURE.
&&
.MARINE...
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...A PRE-FRONTAL TROF WILL DEVELOP ACROSS THE
EAST CENTRAL CAROLINAS TODAY...AND MESH WITH THE APPROACHING COLD
FRONT TONIGHT. THIS FRONT WILL JUST REACH THE CAROLINA COASTS
AROUND DAYBREAK SUNDAY. THE SFC PRESSURE PATTERN AND TIGHTENING
GRADIENT AHEAD OF THE INLAND TROF WILL PRODUCE A SOLID SSW-SW WIND
AT 15 TO 20 KT...WITH A FEW GUSTS UP TO 25 KT POSSIBLE ACROSS THE
ILM NC WATERS. SIGNIFICANT SEAS WILL PRIMARILY BE A FUNCTION OF
THE 4 TO 6 SECOND PERIOD LOCALLY PRODUCED WIND DRIVEN WAVES.
THEREFORE...EXPECT A QUICK BUILDING OF THE SEAS BY THIS AFTERNOON
WITH 3 TO 5 FT ILM NC WATERS AND 3 TO 4 FT FOR THE ILM SC WATERS.
THE PROGGED AFTERNOON AND EVENING WIND AND SEAS COMBO FORECAST
WILL EXCEED SMALL CRAFT EXERCISE CAUTION THRESHOLDS FOR THE ILM NC
WATERS. WILL ISSUE THE SCEC FOR THE HOURS BETWEEN NOON TODAY
THROUGH 6 AM SUNDAY. A PINNED SEA BREEZE COULD PRODUCE A SLIGHT
BACKING OF THE WINDS NEAR SHORE TO S-SSW THIS AFTERNOON AND EARLY
EVENING. THE RELATIVELY COOLER NEAR SHORE WATERS...60S SSTS...WILL
HAVE A TREND TO WEAKEN THUNDERSTORMS THAT MOVE OFF THE MAINLAND
LATER TODAY. WILL HIGHLIGHT IN THE HWO FOR THE THREAT FOR 25 TO 35
KT WIND GUSTS FROM CONVECTION MOVING OFF THE MAINLAND.
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...A COLD FRONT WILL CROSS THE WATERS EARLY SUNDAY
WITH WINDS SHIFTING FROM SOUTHWEST TO NORTH. WIND SPEEDS WILL
REMAIN TEPID WITH THE WIND SHIFT...ON THE LOWE SIDE OF 10-15 KNOTS
UNTIL MONDAY WHEN A SECONDARY SHORTWAVE WITH DECENT COLD AIR
ADVECTION ARRIVES. SPEEDS AT THIS TIME WILL INCREASE BRIEFLY TO
15-20 KNOTS. BY TUESDAY MORNING...SPEEDS WILL LIKELY DROP A COUPLE
OF KNOTS. SIGNIFICANT SEAS WILL HOVER IN A 2-4 FOOT RANGE WITH THE
HIGHER VALUES MAINLY CONFINED TO THE OUTER WATERS.
.LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...HIGH PRESSURE WILL MOVE QUICKLY FROM THE
APPALACHIANS TO OFF THE SOUTHEAST COAST BY THE END OF THE PERIOD.
NORTHERLY WINDS WILL QUICKLY BACK TO A WEAK...LESS THAN TEN KNOTS...
SOUTHWESTERLY DIRECTION BY MIDDAY WEDNESDAY. THE DEVELOPMENT OF A
PIEDMONT TROUGH EARLY THURSDAY WHICH IS MORE INDICATIVE OF A MID
SUMMER PATTERN WILL INCREASE THE GRADIENT BACK TO THE HIGHER END OF
A 10-15 KNOT RANGE. SEAS WILL BE THE HIGHEST EARLY WITH SOME FOUR
FOOTERS ACROSS THE OUTER WATERS. HEIGHTS REALLY DIMINISH WEDNESDAY
BEFORE INCREASING ONCE AGAIN EARLY THURSDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DL
MARINE...
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
640 PM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT CROSSING NORTHWEST OHIO WILL MOVE EAST OF THE AREA
TONIGHT. CHILLY HIGH PRESSURE FROM CENTRAL CANADA WILL BUILD OVER
THE REGION BY MONDAY. A WARM FRONT WILL DEVELOP OVER THE MIDWEST
ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
NO MAJOR CHANGES FOR THE EARLY EVENING UPDATE. MADE "SHOWERS
LIKELY" FOR MOST OF THE NORTHWEST OHIO ZONES SINCE THE FRONT IS
NOT FAR AWAY. THE ACTUAL TIME LENGTH OF THE SHOWERS WILL BE
SHORT...LESS THAN AN HOUR. ALSO ISSUED A"NOWCAST" MENTIONING THE
GUSTY NATURE OF THE SHOWERS. GUSTS OF 35 TO 40 MPH POSSIBLE.
THE COLD FRONT WILL WORK ITS WAY ACROSS THE AREA THIS EVENING. THE
TROUGH ALOFT IS SHARP AND THERE IS A LOT OF MOMENTUM TO THE FRONT.
SP DESPITE COMING INTO AN AREA OF STABLE AIR...THINK THERE IS A
DECENT CHANCE OF A SHOWER IN MOST AREAS ESPECIALLY FARTHER NORTH UP
TOWARD LAKE ERIE AND IN THE HIGHER TERRAIN OF NE OH/NW PA. DID NOT
MENTION THUNDER ALTHOUGH AN ISOLATED FLASH OF LIGHTNING NOT OUT OF
THE QUESTION. SOME OF THE SHOWERS WILL BE GUSTY...WITH A 35 KNOT
LOW LEVEL NORTHWEST JET AND STRONG COLD ADVECTION FOLLOWING THE
FRONT. DRIER AIR AND SUBSIDENCE WILL ALSO FOLLOW THE FRONTAL PASSAGE
AND EXPECT CLEARING FROM WEST TO EAST. LOWS WILL DROP INTO THE UPPER
30S MOST AREAS...LOWER/MID 40S NEAR LAKE ERIE. TAKE THE COAT IF YOU
ARE GOING TO BE OUT LATER TONIGHT OR EARLY SUNDAY MORNING.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
WITH COLD AIR ALOFT...STEEP LAPSE RATES WILL DEVELOP SUNDAY...
ESPECIALLY WITH A LITTLE MORNING SUNSHINE HEATING UP THE BOUNDARY
LAYER. CUMULUS WILL BUILD AND A FEW SHOWERS WILL DEVELOP... MAINLY
IN AND NEAR THE SNOWBELT OF NE OH/NW PA.
USED THE RAW GFS DATA FOR THE HIGHS SUNDAY...THE MOS GUIDANCE IS
STRONGLY BIASED BY CLIMATOLOGY THIS TIME OF YEAR. IT GAVE UPPER 40S
AND LOWER 50S...A FEW DEGREES BELOW GUIDANCE WHICH SEEMS REASONABLE.
A BRISK NORTHWEST WIND WILL COMPOUND THE CHILL. 850MB TEMPERATURES
WILL DROP TO -4 TO -6C.
THE CENTER OF THE SURFACE HIGH WILL STAY TO THE WEST SUNDAY NIGHT
AND IT WILL TAKE A WHILE FOR THE CUMULUS/STRATOCUMULUS TO DISSIPATE.
THE WIND WILL TAKE A WHILE TO SETTLE. NOT THE BEST CONDITIONS FOR
FROST OR RADIATIONAL COOLING. THAT BEING SAID...THE ACTUAL AIR
TEMPERATURES WILL DROP PRETTY CLOSE TO FREEZING EXCEPT NEAR THE LAKE
ERIE LAKE SHORE. WE PROBABLY WILL NOT SEE AN EXTENDED PERIOD OF
HOURS AT OR BELOW FREEZING AND WILL NOT ISSUE A FREEZE WATCH BUT WE
COULD JUST TOUCH FREEZING IN MANY SPOTS FOR LOWS. THINK THE BEST
APPROACH IS JUST TO KEEP FORECASTING FROST AND THEN ISSUE A FROST
ADVISORY WITH THE SUNDAY FORECAST FOR SUNDAY NIGHT. THE SNOWBELT AND
LAKESHORE WILL PROBABLY NOT SEE MUCH IN THE WAY OF FROST SUNDAY
NIGHT BUT IT COULD BE COLD ENOUGH FOR A FEW WET SNOW FLAKES TO MIX
WITH THE REMAINING SHOWERS.
THE RIDGE WILL BUILD IN ON MONDAY. FAIR WEATHER CUMULUS AND
STRATOCUMULUS AGAIN ARE LIKELY. HIGHS AGAIN BELOW NORMALS...IN THE
50S WITH SOME UPPER 40S EXTREME NE OH/NW PA. THE COLDEST LOWS ON
MONDAY NIGHT WILL SWITCH FROM NW OHIO TO EXTREME NE OH/NW PA. WILL
CONTINUE TO MENTION FROST FOR MONDAY NIGHT NE OH/NW PA.
SOME WARM ADVECTION CLOUDS ARE PROGGED TO SPREAD IN LATE MONDAY
NIGHT AND TUESDAY. A SPRINKLE OR BRIEF SHOWER CAN SOMETIMES OCCUR
WITH THESE DIFFERENTIAL ADVECTION SYSTEMS AND WILL HAVE A SLIGHT
CHANCE OF A SHOWER IN THE FORECAST TUESDAY. WILL AGAIN KEEP TEMPS A
LITTLE BELOW GUIDANCE TUESDAY...MOSTLY UPPER 50S AND LOWER 60S...
BASED ON THE INCREASING CLOUDS AND BIAS TO THE GUIDANCE THIS
TIME OF YEAR.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
MODELS ARE NOT QUITE IDENTICAL IN THEIR SOLUTIONS BUT THEY ARE BOTH
HINTING AT A WARM UP AS WE APPROACH THE MIDDLE OF NEXT WEEK. BROAD
UPPER LEVEL RIDGE IS PROGGED TO BUILD INTO THE FORECAST AREA BY MID
WEEK AND THEN FLATTEN TO BECOME ZONAL ACROSS THE ENTIRE UNITED
STATES BY THURSDAY. THIS SHOULD HELP BRING A BOOST OF WARMER AIR
INTO THE FORECAST AREA THAT WILL LAST RIGHT ON INTO THE END OF THE
WEEK AND WEEKEND. THERE IS NO INDICATION THAT ANY STRONG SURGES OF
COLD AIR WILL SLIDE SOUTH INTO THE FORECAST AREA DURING THIS PERIOD
AND LETS HOPE THIS IS THE LAST ONE.
ONE ISSUE WE WILL HAVE TO CONTEND WITH IS THE FACT THAT WITH THE
WARMER AIR AND HIGHER DEW POINTS...THE THREAT FOR PRECIPITATION WILL
INCREASE. THE OTHER FACTOR IS THE POTENTIAL FOR SOME KIND OF
BOUNDARY...WHETHER IT BE A STATIONARY FRONT OR WARM FRONT...WILL
LINGER AROUND THE REGION. THIS COULD VERY WELL BE THE FOCUSING
MECHANISM THAT COULD PRODUCE A CHANCE FOR SHOWERS AND THUNDERSTORMS
FOR EACH DAY DURING THE PERIOD.
DUE TO THE FACT THAT WE ARE IN MID MAY NOW AND THE SUN ANGLE IS
HIGH...THERE EXISTS THE POTENTIAL FOR TEMPERATURE BUSTS ON THE LOW
END THROUGH THIS PERIOD. WE COULD POSSIBLY SEE TEMPERATURES IN THE
80S EACH DAY RATHER THAN THE 70S FOR HIGHS. BUT...TO REMAIN
CONSISTENT AND COLLABORATED...WILL ERR ON THE SIDE OF LOWER END
UNTIL GET GET A BETTER FIX ON THE MODELS EXPECTED SOLUTION AFTER MID
WEEK.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
COLD FRONT NOW ENTERING NWRN OHIO AND BY 00Z SHOULD BE EAST OF
KTOL SO WILL START OUT KTOL AND KFDY IN POST FRONT NWLY FLOW AND
MVFR CIGS FOR A COUPLE HOURS AND THEN ALLOW CONDITIONS TO GO VFR.
BASED ON HRRR TIMING WILL BRING FRONT THROUGH KMFD AT 01Z AND KCLE
AT 0130Z. FRONT SHOULD REACH KYNG AROUND 03Z. EXPECT AN HOUR OR
TWO OF GUSTY WNW FLOW THEN DIURNAL DECREASE TO ABOUT 10KTS OR SO.
EXPECT VFR CIGS TO DEVELOP MOST LOCATIONS ON SUNDAY WITH POSSIBLY
SOME MVFR IN SCATTERED SHOWERS OFF THE LAKE EXTREME NERN OHIO AND
NWRN PA. SUNDAY SHOULD BE FAIRLY WINDY WITH WNW FLOW GUSTING 25 TO
30KTS.
.OUTLOOK...NON VFR POSSIBLE SUNDAY NIGHT AND MONDAY IN NE OH/NW
PA. ALSO POSSIBLE TUESDAY NIGHT.
&&
.MARINE...
COLD FRONT IS EXPECTED TO SWEEP EAST ACROSS THE LAKE THIS EVENING.
THIS FRONT WILL HAVE A BIT OF A PRESSURE WAVE WITH IT AND EXPECT
WINDS TO JUMP UP ALONG THE BOUNDARY. THE WINDS SHOULD DIMINISH A BIT
OVERNIGHT AND THEN PICK UP AGAIN AS MIXING TAKES PLACE DURING THE
DAY TOMORROW. WINDS COULD VERY WELL REACH 30 KNOTS ON THE LAKE AND
POTENTIALLY POKE INTO GALE FORCE TERRITORY FOR A SHORT PERIOD.
SO...FOR NOW WILL LEAVE GALE FORCE WINDS OUT OF THE FORECAST SINCE
THE DURATION SHOULD BE VERY SHORT. HOWEVER...WILL GO WITH A SMALL
CRAFT ADVISORY FOR LATER THIS AFTERNOON AND CONTINUE IT THROUGH
ABOUT MID DAY ON MONDAY. MAY NEED TO EXTEND IT FURTHER ON MONDAY FOR
THE EASTERN PORTIONS OF THE LAKE.
AS HIGH PRESSURE BUILDS EAST TOWARD THE AREA...A GRADUAL DECREASE IN
THE WINDS CAN BE EXPECTED FOR MONDAY INTO TUESDAY. HOWEVER...AS HIGH
PRESSURE MOVES EAST OF THE LAKE...WINDS WILL BEGIN TO PICK BACK UP
AGAIN OUT OF THE SOUTH TO SOUTHWEST WEDNESDAY AND THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT MONDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...KOSARIK
NEAR TERM...KOSARIK
SHORT TERM...KOSARIK
LONG TERM...LOMBARDY
AVIATION...TK
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
759 AM EDT SAT MAY 11 2013
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO MOVE EAST AND OUT OF THE OHIO VALLEY
THIS MORNING. AN UPPER LEVEL LOW AND A WEAK SECONDARY COLD FRONT
WILL CROSS THE REGION THIS AFTERNOON AND EARLY EVENING...SPARKING
SOME SHOWER ACTIVITY. AFTER THIS...HIGH PRESSURE WILL BUILD IN THE
MID SECTION OF THE COUNTRY WITH DRIER AND COOLER AIR CONTINUING TO
FILTER INTO THE OHIO VALLEY ON NORTHERLY WINDS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
QUICK EARLY MORNING UPDATE JUST SENT. NEEDED TO ACCOUNT FOR RATHER
DECENT COVERAGE OF -DZ THIS MORNING - NOT SHOWING UP SO MUCH IN
ASOS/AWOS DATA - BUT CLEARLY SEEN BY LONG PULSE/SENSITIVE VCP 31
KILN RADAR SWEEPS AND TDWR DATA ACROSS THE AREA. THIS SHOULD
CONTINUE THROUGH THE MORNING BUT AS CEILINGS LIFT JUST A BIT
SHOULD BECOME MORE AND MORE LIMITED TOWARD AFTERNOON. MADE A
RATHER SIGNIFICANT ADJUSTMENT TO TEMPS. LATEST 09Z HRRR AND 10Z
RAP...AS WELL AS 11.06Z RUNS OF NAM WRF AND GFS ALL SHOWING WEAK
CAA TO CONTINUE COINCIDENT WITH EXPANSIVE STRATUS. ALL THESE DATA
SHOW MINIMUM POOL OF SFC-900MB TEMPS ACROSS I-71 CORRIDOR INTO
AFTN AND THUS THIS SHOULD AFFECT TEMPS - SO PULLED BACK QUITE A
BIT - MUCH TOWARD 11.00Z MET MOS VALUES WHICH SEEM A LOW OUTLIER
BUT PROBABLY CLOSER TO REALITY. FEAST OR FAMINE THIS TIME OF
YEAR...AN EXTRA HOUR OR TWO OF SUN WILL BOOST TEMPS...SO WATCHING
SKY COVER CLOSELY TODAY. COLD FRONT/SHRA RIGHT NOW JUST PUSHING
THRU MADISON/QUAD CITIES AND WILL BE HERE LATER THIS AFTN/EVE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
ANY RAIN WITH THE SECONDARY FRONT WILL BE FINISHED EARLY IN THE
EVENING AND CONTINUED WEST-NORTHWEST FLOW WILL HELP USHER IN
OVERNIGHT LOW TEMPERATURES IN THE MID TO UPPER 30S. DO NOT BELIEVE
THAT THERE IS A THREAT FOR FROST AS WIND SPEEDS WILL BE 10 MPH OR
SO AND TEMPERATURES WILL NOT BE COLD ENOUGH FOR A FREEZE.
THE COLD AIR WILL CONTINUE TO BE PULLED INTO THE REGION ON SUNDAY
AND HIGHS SHOULD BE 5 DEG COOLER ON AVERAGE THAN WHAT OCCURS
TODAY. AM SLIGHTLY CONCERNED ABOUT SOME INCREASE IN CLOUDS ALONG
THE OHIO RIVER SUNDAY NIGHT. WHILE THE SETTLING HIGH PRESSURE
SYSTEM AND COOL AIR WILL RESULT IN A NICE RADIATIONAL COOLING
SETUP OVER THE REGION...OPERATIONAL MODELS ARE ALL HINTING AT A
LITTLE MAXIMA OF MOISTURE CUTTING FROM EAST CENTRAL INDIANA INTO
SOUTHWEST OHIO AND NORTHEAST KENTUCKY. THIS COULD LIMIT ANY FROST
POTENTIAL TOMORROW NIGHT/MONDAY MORNING IN THIS AREA. FROST
REMAINS A STRONG POSSIBILITY OVER CENTRAL OHIO DURING THIS TIME
HOWEVER.
TEMPERATURES WILL BEGIN TO REBOUND ON MONDAY AS THE HIGH SETTLES
EAST OF THE REGION AND RETURN FLOW CAN SET UP UNDER A RELATIVELY
CLEAR SKY COVER DURING THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
FCST PERIOD BEGINS WITH HIGH PRESSURE BUILDING IN WITH CAA PROVIDING
BELOW NORMAL TEMPERATURES THROUGH MONDAY. STILL EXPECTING NEAR
RECORD LOWS FOR SUNDAY NIGHT WITH FROST POTENTIAL. MODELS HINTING AT
A LITTLE MOISTURE OFF THE LAKE ENOUGH TO PRODUCE SOME CLOUDS LATE
SUNDAY NIGHT WHICH MAY KEEP TEMPS FROM REACHING RECORD VALUES. WAA
SETS UP FOR MONDAY NIGHT/TUESDAY. MODELS ARE INDICATING INCREASING
MOISTURE AND HAVE PUT IN A SMALL POP FOR NOW. THIS MAY HAVE TO BE
INCREASED IF TRENDS CONTINUE. TEMPS WILL BE SLOWER TO REBOUND
BECAUSE OF CLOUDS AND POSSIBLE SHOWERS. WILL TREND DOWNWARD BUT NOT
AS LOW AS GUIDANCE FOR NOW. SHOULD SEE DRY DAY FOR WEDNESDAY WITH
STRONG HEATING. HAVE BUMPED UP TEMPS CLOSE TO GUIDANCE. MODELS NOT
COMPLETELY IN AGREEMENT FOR SYSTEM FOR WEDNESDAY NIGHT AND THURSDAY.
ECMWF KEEPS FRONT TO THE NORTH WHILE OTHER MODELS BRING FRONT INTO
OHIO VALLEY REGION WITH SHOWERS AND STORMS FOR WEDNESDAY NIGHT AND
THURSDAY. HAVE KEPT POPS IN FOR THIS SCENARIO BUT REMAINING LOW WITH
UNCERTAINTY. COOLER TEMPS FOR THURSDAY BUT MAY NOT BE AS COOL IF
ECMWF MODEL IS CORRECT. SYSTEM LINGERS IN THE AREA THROUGH FRIDAY
AND HAVE CONTINUED LOW POPS IN UNTIL MORE CERTAIN OF MODEL
CONSISTENCY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
MVFR TO IFR CEILINGS WILL CONTINUE ACROSS THE AREA THIS MORNING.
WEAK HIGH PRESSURE BRIEFLY NOSING INTO THE REGION TODAY SHOULD
RESULT IN SOME GRADUAL IMPROVEMENT IN THE CEILINGS BY MIDDAY...BUT
EXPECT MVFR CEILINGS FOR MOST OF THE DAY. WINDS WILL SHIFT BACK TO
THE WEST EARLY THIS AFTERNOON AHEAD OF ANOTHER COLD FRONT APPROACHING
FROM THE NW. THAT FRONT WILL BRING ANOTHER CHANCE OF SHOWERS AS IT
CROSSES THE REGION LATE THIS AFTERNOON AND EVENING. EXPECT THE
SHOWERS TO QUICKLY MOVE OUT OF THE AREA BY AROUND 04Z SUNDAY.
CONTINUING WITH VCSH MENTION IN THE TAFS FOR NOW. EXPECT BREEZY
CONDITIONS FOR A TIME THIS EVENING AS THE FRONT MOVES THROUGH...
OTHERWISE VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE TAF
PERIOD.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...BINAU
SHORT TERM...FRANKS
LONG TERM...PADGETT
AVIATION...KURZ
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
522 PM MDT SUN MAY 12 2013
.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 255 PM MDT SUN MAY 12 2013
MASSIVE WESTERN CONUS UPPER RIDGE CONTINUES TO PUSH
EAST WITH DEEP LAYER THETA-E RIDGING ONGOING. LEE SIDE TROUGH
WILL ADVECT EAST AWAY FROM THE ROCKIES ON THE LEADING EDGE OF
UPPER LEVEL HEIGHT RISES...WITH A STRONG UPPER LEVEL TROUGH
EXPECTED TO ADVANCE INTO THE NORTHERN PLAINS MONDAY
NIGHT...SUPPORTING ANOTHER MORE PRONOUNCED LL TROUGH INTO THE
REGION. OVERALL...MAINLY DRY WEATHER EXPECTED...SAVE FOR PORTIONS
OF THE BLACK HILLS WHERE LL THETA-E ADV COUPLED WITH STEEPENING
MID LEVEL LAPSE RATES AND LOCAL OROGRAPHIC CONVERGENCE MAY SUPPORT
ISOLD SHRA/TS LATE THIS AFTERNOON/EARLY EVENING AND AGAIN MONDAY
AFTERNOON/EVENING. OTHERWISE...A SIG WARM NOSE ASSOCIATED WITH THE
ADVANCING RIDGE IS EXPECTED TO KEEP CONVECTION AT BAY ELSEWHERE.
LATE THIS AFTERNOON/TONIGHT...REMOVED LOW POPS OVER THE
CENTRAL/SOUTHERN BH. NEARLY ALL HIRES MODELS DO NOT GENERATE ANY
CONVECTION...WITH THE NAM BEING THE ONLY MODEL/OUTLIER THAT DOES.
LATEST RAP BUFR PROGS INDICATE MID LEVEL WARMING IS STRONGER/FASTER
THAN PREVIOUS INDICATIONS...WITH A DOWNTREND IN CU NOTED IN SAT
TRENDS. OTHERWISE...A WARM NIGHT EXPECTED WITH LOWS IN THE 50S AT
MANY PLACES. THERE IS A SMALL POTENTIAL FOR AN ELEVATED SHOWER
ACROSS THE FAR NORTH GIVEN THETA-E ADV AT THE BASE OVER THE GROWING
WARM NOSE WITH NEGATIVE SW INDICES. HOWEVER...GIVEN THE LOW
POTENTIAL HAVE LEFT OUT AND WILL LET THE NEXT SHIFT ASSESS.
MONDAY...LEAD LL TROUGH WILL ADVECT EAST ACROSS THE AREA IN THE
MORNING...WITH ONGOING DEEP LAYER WAA. INCREASED LL MOISTURE MAY BE
SUFFICIENT ENOUGH TO GENERATE ISOLD CONVECTION OVER THE BH...ESP
WITH A WEAK MESO LOW AS INDICATED IN THE NAM. RETAINED SLIGHT CHANCE
POPS THERE. OTHERWISE...VERY WARM CONDITIONS EXPECTED WITH LOW TO
MID 90S OVER THE SD PLAINS...COOLER WEST. CURRENT FORECAST TEMPS
SURPASSES THE RECORD OF 92 AT THE RAPID CITY AIRPORT...NEARING THE
DOWNTOWN RECORD OF 94. A VERY WARM NIGHT IS IN STORE FOR MONDAY
NIGHT...WITH LOWS IN THE 60S AT MANY PLACES GIVEN ONGOING SFC
PRESSURE FALLS PER THE ADVANCING DEEP NORTHERN STREAM UPPER IMPULSE.
THIS WILL SUPPORT A MIXED BL WITH GUSTY WINDS POTENTIALLY AT MANY
LOCATIONS...ESP OVER THE NORTHERN BH FOOTHILLS...GIVEN A NEAR 5 MB
SFC PRESSURE DIFFERENTIAL FROM THE BH TO THE PLAINS. RECORD HIGH
MIN/S MAY BE SET AT RAPID CITY.
&&
.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 255 PM MDT SUN MAY 12 2013
UPPER LEVEL RIDGE BREAKS DOWN BY TUESDAY MORNING AS A SURFACE LOW
PASSES TO THE NORTH AND A STRONG COLD FRONT SLIDES QUICKLY ACROSS
THE FORECAST AREA DURING THE MORNING. STRONG NORTHWEST WINDS CAN BE
EXPECTED ACROSS THE NORTHWEST AND WEST CENTRAL SOUTH DAKOTA PLAINS
BEHIND THE FRONT. THE STRONGEST WINDS LOOK TO BE NEAR THE ND BORDER.
HAVE DECIDED TO ISSUE A HIGH WIND WATCH FOR HARDING AND PERKINS
COUNTIES...WHERE SUSTAINED WINDS OF 40 MPH OR MORE LOOK POSSIBLE...
ESPECIALLY DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. HIGH
TEMPERATURES WILL RANGE FROM THE LOWER 70S OVER FAR NORTHWESTERN SD
AND PORTIONS OF NORTHEASTERN WY TO THE UPPER 80S ACROSS SOUTH
CENTRAL SD. DEPENDING ON THE EXACT TIMING OF THE FRONT AND HOW
QUICKLY THE DRIER AIR PUSHES IN BEHIND THE FRONT...THERE IS SOME
POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP ACROSS
PORTIONS OF THE SD PLAINS TUESDAY AFTERNOON. WILL LET LATER SHIFTS
HAVE A LOOK AT UPDATED MODEL DATA FOR THIS POTENTIAL AND WHETHER A
FIRE WX WATCH MAY BE NEEDED.
MORE SEASONABLE TEMPS ARE EXPECTED FOR THE REMAINDER OF THE
WEEK...THOUGH STILL ABOVE AVERAGE...AS AREA REMAINS UNDER ZONAL
FLOW. WEAK DISTURBANCES WITHIN THIS FLOW WILL BRING SOME CHANCES FOR
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS LATE IN THE
WEEK...WITH CHANCES LIKELY INCREASING BY THE WEEKEND. LATEST GFS AND
ECMWF BOTH CONTINUE TO SHOW A STRONGER UPPER TROF IMPACTING THE
REGION FROM LATE FRIDAY THROUGH THE WEEKEND...BRINGING THE POTENTIAL
FOR MORE WIDESPREAD PCPN AND OUR FIRST SEVERE WX OF THE SEASON.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 520 PM MDT SUN MAY 12 2013
VFR CONDITIONS ARE EXPECTED THROUGH MONDAY AFTERNOON.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON
FOR SDZ001-002.
WY...NONE.
&&
$$
SHORT TERM...JC
LONG TERM...26
AVIATION...BUNKERS
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1140 PM CDT FRI MAY 10 2013
.DISCUSSION...
SEE THE 06Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
MID LEVEL CLOUDS CONTINUE TO STREAM ACROSS THE REGION AND WILL DO
SO FOR MUCH OF THE PERIOD AS THE UPPER CYCLONE SPINS OVER NORTHERN
MEXICO. A FEW HIGH BASED ECHOES REPRESENT VERY LIGHT SHOWERS THAT
MAY CAUSE A FEW SPRINKLES OVERNIGHT BUT THIS SHOULD HAVE MINIMAL
IMPACT. HOWEVER...THE HI RES CONVECTION MODELS INDICATE THAT
ISOLATED ELEVATED CONVECTION MAY DEVELOP LATE TONIGHT OVER THE
SOUTHERN HALF OF THE CWA. I HAVE LEFT THE TAFS DRY GIVEN THE HIGH
UNCERTAINTY BUT DID INCLUDE A FEW CLOUDS AROUND 4000 FT BY 12Z AT
KSJT. OTHERWISE...WE WILL SEE THE BEST RAIN CHANCES TOMORROW ALONG
THE I-10 CORRIDOR FROM KSOA TO KJCT...MAINLY DURING THE DAYTIME
HOURS. VFR CONDITIONS WILL PREVAIL WITH THE EXCEPTION BEING
TEMPORARY REDUCTIONS IN VIS/CEILINGS IN AND AROUND ANY STORMS
THAT MAY DEVELOP. EXPECT LIGHT NORTH WINDS OVERNIGHT BECOMING
NORTHEAST AT 10-12 KTS FOR SATURDAY.
JOHNSON
&&
.PREV DISCUSSION... /ISSUED 847 PM CDT FRI MAY 10 2013/
UPDATE...
SEE UPDATE DISCUSSION BELOW.
DISCUSSION...
UPDATED ZONES AND GRIDS TO REDUCE POPS TO SLGT CHC AND REMOVE
THUNDER FOR TONIGHT.
21
PREV DISCUSSION... /ISSUED 718 PM CDT FRI MAY 10 2013/
UPDATE...
SEE UPDATE DISCUSSION BELOW.
DISCUSSION...
UPDATED ZONES AND HAZARD GRID TO CANCEL SEVERE THUNDERSTORM WATCH
#156. ALSO...UPDATED HOURLY TEMPS DUE TO CURRENT READINGS IN THE
60S ACROSS MUCH OF THE AREA.
21
PREV DISCUSSION... /ISSUED 617 PM CDT FRI MAY 10 2013/
DISCUSSION...
SEE 00Z AVIATION DISCUSSION BELOW.
AVIATION...
SCATTERED TSTMS CURRENTLY OVER THE HEARTLAND AND NORTHWEST HILL
COUNTRY WILL EXIT THE AREA BY 01Z. ISOLD TSTMS WILL STILL BE
POSSIBLE THIS EVENING MAINLY SOUTH OF THE I-20 CORRIDOR. HAVE A
VCTS GOING AT THE KJCT AND KBBD TERMINALS THROUGH 02Z. OTHERWISE
MAINLY VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS...WITH
ABUNDANT HIGH CLOUDS OVER WEST CENTRAL TEXAS. WINDS WILL BE NORTH
WITH GUSTS TO NEAR 30 KNOTS THROUGH 02Z AT THE KSOA AND KBBD
TERMINALS.
21
PREV DISCUSSION... /ISSUED 322 PM CDT FRI MAY 10 2013/
SHORT TERM...
BAND OF STRONG TO SEVERE THUNDERSTORMS IN THE CONCHO VALLEY
SOUTHWEST INTO CROCKETT COUNTY...ASSOCIATED WITH A COLD
FRONT...WAS STEADILY MOVING SOUTHEAST THIS AFTERNOON. A SEVERE
THUNDERSTORMS WATCH IS IN EFFECT FOR MUCH OF WEST CENTRAL
TEXAS...SOUTH OF THE BIG COUNTRY UNTIL 10 PM CDT TONIGHT.
ATMOSPHERE WAS UNSTABLE THIS AFTERNOON AS COLDER AIR
ALOFT...ASSOCIATED WITH AN UPPER LEVEL TROUGH OVER NEW MEXICO
MOVED EAST. SPC RAP SB CAPES WERE 1500-2500 J/KG. THIS IS LOWER
THAN YESTERDAY...BUT STILL ENOUGH TO GET GOLF BALL SIZE HAIL IN
COKE COUNTY FROM A SUPERCELL THIS AFTERNOON.
SEVERE STORM ACTIVITY SHOULD NOT BE QUITE AS EXTENSIVE AS
YESTERDAY...AND SHOULD WEAKEN BY SUNSET WITH LOSS OF DAYTIME
HEATING AND PASSAGE OF THE COLD FRONT.
STILL KEEPING A CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AS
THE UPPER TROUGH MOVES ACROSS THE REGION. DRIER AIR WILL ALSO MOVE
IN FROM NORTH TO SOUTH...SO SEVERE THUNDERSTORMS ARE NOT EXPECTED.
MOST STORMS SHOULD BE ALONG THE I-10 CORRIDOR AND END BY LATE
AFTERNOON.
04
LONG TERM...
SHOWER AND THUNDERSTORM CHANCES RETURN TUESDAY AS A CUT OFF UPPER
LOW OVER BAJA CALIFORNIA MOVES NORTHEAST AND WEAKENS OVER NEW
MEXICO AND THE TEXAS PANHANDLE. MOVEMENT AND PLACEMENT OF CUT OFF
UPPER LOWS HAS ALWAYS BEEN DIFFICULT...ESPECIALLY WHEN THEY KICK
OUT. WILL KEEP POPS FAIRLY LOW AT THIS TIME...IN THE 20 TO 30
PERCENT RANGE...WITH THE HIGHER POPS ALONG THE I-10 CORRIDOR.
THUS IT POSSIBLE THAT THE SYSTEM BEGIN TO MOVE SLOWER THAN
FORECAST...DESPITE FAIRLY GOOD AGREEMENT IN RUN CONTINUITY AND
BETWEEN THE GFS AND EC MODELS. REMOVED POPS BY THURSDAY AS THE
UPPER DISTURBANCE MOVES NE AND AN UPPER RIDGE BUILDS IN.
04
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 56 80 54 79 58 / 20 10 10 5 5
SAN ANGELO 58 79 54 81 55 / 20 20 10 10 5
JUNCTION 58 77 53 81 53 / 20 20 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION
NWS SPOKANE WA
642 PM PDT Sun May 12 2013
.SYNOPSIS...
On Monday a vigorous upper level disturbance will bring the first
period of widespread precipitation to the region in over three
weeks with locally heavy downpours and thunderstorms. The arrival
of cooler, more seasonal temperatures Tuesday through the upcoming
weekend will allow many rivers to recede.
&&
.DISCUSSION...
Radar imagery shows that thunderstorms will clip the Camas Prairie
area this evening. Areas north of the Camas Prairie are quite a
bit more stable due to a persistent mid and high level cloud deck
that hung in all day. The forecast has been updated to dry things
out for this evening on the Palouse, Lewiston, and Central
Panhandle Mountains. Meanwhile a stalled mid level front from
Moses Lake to Spokane to Sandpoint is producing mainly virga (rain
that evaporates before reaching the ground). Models show this
front gradually falling apart tonight...with mainly sprinkles or
light showers expected out of it. The forecast has been updated
based on these latest trends. JW
&&
.AVIATION...
00Z TAFS: A stalled mid level front will result in abundant mid and
high level cloud cover tonight. Isolated rain showers may also fall
out of this. Radar trends and HRRR data suggest isolated
thunderstorms over NE Oregon this evening should remain south of
KLWS. On Monday a fast moving strong cold front will cross into
Central and far NE Washington 12-18z...spreading through the
remainder of Eastern Washington and North Idaho between 18z Mon-00z
Tue. Most areas will see a 3-6 hour period of rain with the front
before rain changes to showers. CIGS should stay primarily VFR
although MVFR can`t be ruled out.
Instability ahead of the front around KLWS could trigger
thunderstorms but the best chances will be south and east of KLWS.
Then behind the front mid level cooling over North Central
Washington will result in towering cumulus developing KEAT/KMWH
around 21z with the chance for isolated thunderstorms mainly in the
Cascades...with the chance for thunder spreading east in the late
afternoon and evening. Stronger winds aloft may result in very
gusty winds with storms that develop. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 55 67 41 62 43 66 / 10 80 50 0 10 10
Coeur d`Alene 52 68 43 62 41 67 / 10 80 50 10 10 10
Pullman 51 69 40 61 40 65 / 10 80 50 0 10 10
Lewiston 58 79 44 71 45 74 / 10 70 40 0 10 10
Colville 50 67 43 67 39 72 / 30 80 60 10 10 20
Sandpoint 49 65 42 62 39 67 / 30 80 80 20 10 10
Kellogg 53 68 42 59 40 64 / 10 80 70 10 10 10
Moses Lake 55 72 46 70 44 74 / 20 40 10 0 0 0
Wenatchee 55 70 47 69 45 72 / 10 60 10 0 10 10
Omak 49 71 42 69 39 73 / 10 60 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
504 PM PDT Sun May 12 2013
.SYNOPSIS...
A cold front will arrive this evening, and bring breezy
conditions to much of the Inland Northwest. On Monday a vigorous
upper level disturbance will bring the first period of widespread
precipitation to the region in over three weeks with locally heavy
downpours and thunderstorms. The arrival of cooler, more seasonal
temperatures Tuesday through the upcoming weekend will allow many
rivers to recede.
&&
.DISCUSSION...
Tonight: There will be two features of note where showers will
focus through this evening into tonight. This first is a mid level
front that has stalled across northwest Oregon into north-central
Washington. We have seen some very light shower activity along the
eastern edge of this front and much of this precip is likely
evaporating before reaching the surface. Radar imagery showed some
enhancement over southwest Washington around 1:30 in the
afternoon indicating a bit more lift across this area possibly due
to a little ripple moving in. The HRRR model takes this
enhancement moves it northeast ward over Wenatchee to Colville
through this evening. As a result, I kept some minor mention of
showers along this area; however, I am not that confident that we
will generate much in the way of measurable rainfall along the front.
The second area of note is a ridge axis in the equivalent
potential temperature field between 850-700 mbs from northeast
Oregon, across the Central Panhandle and into western Montana.
Visible satellite imagery is showing signs of some surface based
convection beginning to fire along this axis and should continue
to develop through at least the early evening hours. There isn`t
much of a trigger coming through to keep convection going through
the night, but the mid level front looks to nudge a bit more
eastward this evening. This may be enough to keep showers going
through the evening from the Northeast Blue Mountains into the
Central Panhandle Mountains. I kept a mention of isolated
thunderstorms in these areas as sounding profiles would suggest
that it is possible. The HRRR model does show the possibility of
40+ dbz echoes as well, but I am not too excited for thunderstorms
this evening. /SVH
Monday and Monday night...This period promises to be a very active
weather period for much of the forecast area as a transition into
a much cooler and spring-like weather pattern arrives. Satellite
indicates a deep and long fetch of moisture impacting the
Northwest Pacific Coast this afternoon...ahead of a deep Gulf of
Alaska trough with the outriding showers creeping into the
forecast area this evening. This situation will be aggravated on
Monday as a vigorous upper level short wave now faintly visible as
a digging wave near 150W tears into the region providing copious
dynamic support with jet divergence...cyclonic diffluence and
differential PVA as well as a healthy surface cold front.
Precipitable water values available for exploitation by this lift
will be on the order of an inch or more...almost 200 percent of
normal. The confluence of all these elements will bring a number
of meteorological inconveniences to the region Monday afternoon
and evening.
Rain showers...
For the first time in weeks a very moist air mass will be
exploited by synoptic forcing into a dense area of hefty and
widespread shower activity...mainly focused over the eastern and
northern zones...but with hit-and-miss showers possible just about
anywhere in the region. On average most locations in the western
basin will experience only a few hundredths of an inch...but
amounts may exceed 1/4 to 1/2 inch east of a line from Republic
to Pomeroy and near the Cascade Crest...with some locations being
run over by multiple showers through the afternoon.
Thunderstorms...While the thunder potential will be fairly small
at any given location...the best chance for appreciable surface
based instability on the order of a few hundred Joules/Kg will be
over the southeastern zones during the afternoon and evening
hours. The magnitude of the forcing and wind shear in the lower
atmosphere suggests that any storms that get going south of a line
from about La Crosse to Mullan Pass have the potential to become
organized and strong producers of hail and gusty winds. north of
this line there will likely be too much cloud cover early in the
day to generate significant SB CAPE any any storms will be hit-
and-miss isolated embedded cells in the predominant shower
activity. These storm cores may also produce brief torrential
downpours but will likely also be fast movers for only a remote
threat of flash flooding.
Synoptic wind...The surface cold front will cross the region from
west to east during the afternoon period. Windy and gusty conditions
will develop over the deep basin during the afternoon and over the
eastern basin in the late afternoon and early evening hours as the
precipitation band exits to the east. The gradient magnitude and
gust potential from mixing does not appear to support Wind
Advisory criteria at this time...but solid 15 to 25 mph sustained
winds with gusts possibly as high as 40 mph will be possible into
the evening over exposed locations of the basin during the
evening hours.
Monday night...After the evening activity dies down...windy
conditions will gradually abate to merely breezy and should keep
overnight lows elevated even with partial clearing.
Tuesday through Wednesday...A general zonal flow regime off the
Pacific will settle over the region during this period. This flow
should keep shower activity to a minimum over the basin...with a
chance of mountain showers (of the snow variety on the higher
peaks) each afternoon and evening north and east of the basin. No
further organized storms or frontal complexes are forecast through
Wednesday. The main story will be cooler and more seasonably
normal temperatures with occasionally breezy conditions. /Fugazzi
Wednesday night to Sunday: A progressive pattern with mean
continued shower chances, especially in the mountains, and near
seasonal temperatures. Models point to at least 2 organized
disturbances entering the West: one around Thursday and Friday and
another toward the weekend. There remains disagreement over
precise timing and track. Regardless embedded smaller-scale
vorticity maxima slip by. With Moisture and instability deepens
later Thursday and especially Friday, with PWATs rising to
120-170% of normal and CAPE values between 100-400 J/kg roughly
across north-central and east WA and north ID. Combined with any
forcing that comes through this will lead to an above average
threat of shower, with a chance of thunderstorms mixed in. Subtle
ridging develops going into Saturday before the next wave rides in
Sunday. This suggests a brief shift in the precipitation threat to
the mountains going into Saturday and early Sunday, before being
chances are renewed by later Sunday. Yet given limited agreement
over precise timing I kept PoPs closer to climatological values
between Saturday and early Sunday. This means while precipitation
chances decline from Friday, they do not end. The main exception
looks to be in the lee of the Cascades and deer Columbia Basin
where the westerly flow and its shadowing effects will hold PoPs
lower. /J. Cote`
&&
.AVIATION...
00Z TAFS: A stalled mid level front will result in abundant mid and
high level cloud cover tonight. Isolated rain showers may also fall
out of this. Radar trends and HRRR data suggest isolated
thunderstorms over NE Oregon this evening should remain south of
KLWS. On Monday a fast moving strong cold front will cross into
Central and far NE Washington 12-18z...spreading through the
remainder of Eastern Washington and North Idaho between 18z Mon-00z
Tue. Most areas will see a 3-6 hour period of rain with the front
before rain changes to showers. CIGS should stay primarily VFR
although MVFR can`t be ruled out.
Instability ahead of the front around KLWS could trigger
thunderstorms but the best chances will be south and east of KLWS.
Then behind the front mid level cooling over North Central
Washington will result in towering cumulus developing KEAT/KMWH
around 21z with the chance for isolated thunderstorms mainly in the
Cascades...with the chance for thunder spreading east in the late
afternoon and evening. Stronger winds aloft may result in very
gusty winds with storms that develop. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 55 67 41 62 43 66 / 10 80 50 0 10 10
Coeur d`Alene 52 68 43 62 41 67 / 20 80 50 10 10 10
Pullman 51 69 40 61 40 65 / 10 80 50 0 10 10
Lewiston 58 79 44 71 45 74 / 20 70 40 0 10 10
Colville 50 67 43 67 39 72 / 30 80 60 10 10 20
Sandpoint 49 65 42 62 39 67 / 30 80 80 20 10 10
Kellogg 53 68 42 59 40 64 / 20 80 70 10 10 10
Moses Lake 55 72 46 70 44 74 / 20 40 10 0 0 0
Wenatchee 55 70 47 69 45 72 / 10 60 10 0 10 10
Omak 49 71 42 69 39 73 / 10 60 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1045 PM CDT SUN MAY 12 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 232 PM CDT SUN MAY 12 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH
PRESSURE STRETCHING FROM SOUTH-CENTRAL CANADA TO THE WESTERN GULF
COAST EARLY THIS AFTERNOON WHILE LOW PRESSURE PEELS AWAY OVER
QUEBEC. AS CYCLONIC FLOW ABATES AND DRIER AIR BUILDS IN FROM THE
WEST...WIDESPREAD MORNING STRATO-CU HAS BEEN RETREATING TO THE
NORTHEAST...TURNING SKIES MOSTLY CLEAR TO PARTLY CLOUDY OVER MUCH OF
CENTRAL AND NORTHEAST WISCONSIN. PLENTY OF CLEAR SKIES BENEATH THE
SURFACE HIGH OFF TO THE WEST...WHICH WILL MOVE INTO THE AREA
TONIGHT. EVEN FARTHER WEST...A WARM FRONT OVER THE LEE OF THE
ROCKIES WILL ENTER THE REGION TOMORROW AFTERNOON. FIRST CONCERN
IS TEMPS TONIGHT...FOLLOWED BY SMALL PRECIP CHANCES TOMORROW
AFTERNOON.
TONIGHT...HIGH PRESSURE OVER THE GREAT PLAINS WILL SHIFT ACROSS THE
WESTERN HALF OF WISCONSIN TONIGHT. AS CLOUDS CONTINUE TO MIX OUT
THIS AFTERNOON...SKIES WILL BECOME CLEAR AND WINDS WILL BECOME LIGHT
AND VARIABLE BY EARLY TO MID-EVENING. GOOD RADIATIONAL CONDITIONS
WILL THEN EXIST FOR THE REST OF THE NIGHT. LOW TEMPS UPSTREAM OVER
WESTERN WISCONSIN AND MINNESOTA WERE MOSTLY AT OR BELOW 32 DEGREES
AND EXPECT SIMILAR READINGS LATE TONIGHT. TEMPS WERE ALSO IN THE 34
TO 36 DEGREE RANGE OVER THE FOX VALLEY AND LAKESHORE LAST
NIGHT...WHEN THERE WAS CONSIDERABLY MORE WIND AND CLOUDS. WILL NOT
HAVE THIS LUXURY TONIGHT...SO FIGURE TEMPS WILL FALL BELOW FREEZING
ACROSS MOST OF THE CWA. WILL EXPAND THE FREEZE WARNING.
MONDAY...HIGH PRESSURE WILL SLIDE TO THE EAST ACROSS THE CENTRAL
GREAT LAKES. WARM ADVECTION WILL RAMP UP ON THE BACKSIDE OF THE
HIGH AT THE SAME TIME AS MID AND HIGH CLOUDS SPILL OVER THE
MID-LEVEL RIDGE AXIS. AS A RESULT...WILL SEE A SLOW INCREASE OF
CLOUDS OVER THE COURSE OF THE DAY. AFTER 21Z...ENOUGH MOISTURE
ADVECTION LOOKS TO TAKE PLACE TO NEARLY SATURATE THE COLUMN OVER
CENTRAL AND NORTH-CENTRAL WISCONSIN. MID-LEVEL LAPSE RATES ARE VERY
POOR...BUT MID-LEVEL FGEN APPEARS SUFFICIENT FOR THE POSSIBILITY OF
SCATTERED LIGHT SHOWERS DEVELOPING. WILL INCREASE POPS INTO THE
40-50 PERCENT RANGE. THERE IS A FAIRLY LARGE RANGE IN GUIDANCE FOR
TEMPS TOMORROW AFTERNOON...BETWEEN THE COLD ECMWF AND WARM NAM.
SPLITTING THE DIFFERENCE SHOULD GET TEMPS CLOSE AND WILL GO WITH
HIGHS IN THE UPPER 50S TO LOW 60S BUT COOLER LAKE SIDE.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 232 PM CDT SUN MAY 12 2013
PCPN TRENDS MONDAY NIGHT INTO TUESDAY NIGHT...THE POTENTIAL FOR
SVR TSTMS TUESDAY NIGHT...GUSTY WINDS ON WEDNESDAY...PCPN TRENDS
NEXT WEEKEND...AND TEMPERATURES THROUGHOUT THE PERIOD ARE THE
MAIN FCST CONCERNS.
STRONG H8 WAA/MOISTURE CONVERGENCE WILL BRING A BAND OF SHOWERS THROUGH
THE AREA ON MONDAY NIGHT. ALTHOUGH THE RAIN WILL NOT LAST LONG AND QPF
AMOUNTS ARE EXPECTED TO BE LIGHT...FELT THAT POPS NEEDED TO BE RAISED
A LITTLE BIT. WAA/ISENT LIFT WILL CONTINUE ON TUESDAY AS A WARM FRONT
LIFTS INTO WISCONSIN. THIS FRONT IS EXPECTED TO MOVE INTO CENTRAL WI
LATE IN THE AFTERNOON. DESPITE SOME PERSISTENT FORCING...AN
INCREASINGLY CAPPED ATMOSPHERE AND LATE ARRIVAL OF THE INSTABILITY
AXIS PRECLUDES ADDING ANYTHING MORE THAN SLGT CHC/CHC POPS...MAINLY
OVER NORTHERN WI. TEMPERATURES WILL VARY GREATLY...WITH READINGS IN
THE MID 50S TO LOWER 60S NEAR THE LAKE...AND INLAND TEMPS RANGING
FROM THE UPPER 60S FAR NE WI TO THE LOWER TO MIDDLE 80S IN C WI.
THE WARM FRONT WILL LIFT NORTH TUESDAY...QUICKLY FOLLOWED BY THE COLD
FRONTAL PASSAGE DURING THE LATE EVENING AND OVERNIGHT HOURS. ELEVATED
CAPE OF 1500-2000 J/KG...VERY STEEP LAPSE RATES OF 7-8 C/KM...DEEP
LAYER SHEAR OF 40-50+ KTS AND 0-3 KM HELICITIES OF 400-500 WILL
PROVIDE PLENTY OF SUPPORT FOR SEVERE TSTMS...BUT CAPPING MAY BE
PROHIBITIVE FOR CONVECTIVE INITIATION. BEST CASE SCENARIO FROM THE
NAM AND A FEW OF THE SREF ENSEMBLE MEMBERS SHOW CINH OF 40-70
J/KG FOR A PARCEL LIFTED FROM THE 850-800 MB LEVEL OVER FAR
NORTHERN WI...BUT OTHER FCST SOUNDINGS SHOWED MUCH HIGHER CINH...
EVEN FROM ELEVATED PARCELS. WILL CONTINUE WITH CHC POPS TUESDAY
EVENING...AND A MENTION OF THE SVR TSTM POTENTIAL IN THE HAZARDOUS
WEATHER OUTLOOK...BUT HAVE TO ACKNOWLEDGE THE POTENTIAL FOR A MAINLY
DRY FCST. ANY PCPN THAT DOES DEVELOP WILL COME TO AN END OVERNIGHT
AS THE COLD FRONT SHIFTS EAST.
CAA...AN INCREASING NW PRESSURE GRADIENT AND DEEP MIXING WILL LEAD
TO A BREEZY/WINDY DAY ON WEDNESDAY. MIXING THROUGH 825-775 MB SUPPORTS
HIGH TEMPS IN THE LOWER TO MIDDLE 70S IN MOST LOCATIONS.
THE COLD FRONT WILL SETTLE SOUTH OF WISCONSIN FROM WEDNESDAY THROUGH
FRIDAY...AS ANOTHER COLD FRONT SAGS SOUTH OUT OF CANADA. WITH THE
REGION IN BETWEEN SYSTEMS...EXPECT A GENERALLY DRY PERIOD OVER THE
LATTER HALF OF THE WORK WEEK...WITH TEMPERATURES AT OR A LITTLE
ABOVE NORMAL.
LOW PRESSURE IS EXPECTED TO APPROACH FROM THE CENTRAL PLAINS THIS
WEEKEND...AND REACH THE IOWA VCNTY BY SUNDAY. AS THIS HAPPENS...
THE FRONT THAT STALLED TO OUR SOUTH WILL LIFT BACK INTO SOUTHERN
WISCONSIN...ALONG WITH ITS ASSOCIATED MOISTURE/ELEVATED INSTABILITY.
THIS SHOULD LEAD TO SHOWERS AND SCT TSTMS OVER THE REGION...ALONG
WITH COOLER TEMPERATURES DUE TO EAST WINDS AND ABUNDANT CLOUD COVER.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1043 PM CDT SUN MAY 12 2013
VFR CONDITIONS TO PREVAIL TONIGHT INTO MONDAY AS A
RIDGE OF HIGH PRESSURE DRIFTS OVER THE GREAT LAKES REGION. MID TO
HIGH LEVEL CLOUDS WILL BE ON THE INCREASE LATER MONDAY AS A WEAK
WARM FRONT APPROACHES FROM THE NORTHERN PLAINS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING UNTIL 7 AM CDT MONDAY FOR WIZ020-022-030-031-
035>040-045-048>050-073-074.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TDH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
636 PM CDT SUN MAY 12 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 232 PM CDT SUN MAY 12 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH
PRESSURE STRETCHING FROM SOUTH-CENTRAL CANADA TO THE WESTERN GULF
COAST EARLY THIS AFTERNOON WHILE LOW PRESSURE PEELS AWAY OVER
QUEBEC. AS CYCLONIC FLOW ABATES AND DRIER AIR BUILDS IN FROM THE
WEST...WIDESPREAD MORNING STRATO-CU HAS BEEN RETREATING TO THE
NORTHEAST...TURNING SKIES MOSTLY CLEAR TO PARTLY CLOUDY OVER MUCH OF
CENTRAL AND NORTHEAST WISCONSIN. PLENTY OF CLEAR SKIES BENEATH THE
SURFACE HIGH OFF TO THE WEST...WHICH WILL MOVE INTO THE AREA
TONIGHT. EVEN FARTHER WEST...A WARM FRONT OVER THE LEE OF THE
ROCKIES WILL ENTER THE REGION TOMORROW AFTERNOON. FIRST CONCERN
IS TEMPS TONIGHT...FOLLOWED BY SMALL PRECIP CHANCES TOMORROW
AFTERNOON.
TONIGHT...HIGH PRESSURE OVER THE GREAT PLAINS WILL SHIFT ACROSS THE
WESTERN HALF OF WISCONSIN TONIGHT. AS CLOUDS CONTINUE TO MIX OUT
THIS AFTERNOON...SKIES WILL BECOME CLEAR AND WINDS WILL BECOME LIGHT
AND VARIABLE BY EARLY TO MID-EVENING. GOOD RADIATIONAL CONDITIONS
WILL THEN EXIST FOR THE REST OF THE NIGHT. LOW TEMPS UPSTREAM OVER
WESTERN WISCONSIN AND MINNESOTA WERE MOSTLY AT OR BELOW 32 DEGREES
AND EXPECT SIMILAR READINGS LATE TONIGHT. TEMPS WERE ALSO IN THE 34
TO 36 DEGREE RANGE OVER THE FOX VALLEY AND LAKESHORE LAST
NIGHT...WHEN THERE WAS CONSIDERABLY MORE WIND AND CLOUDS. WILL NOT
HAVE THIS LUXURY TONIGHT...SO FIGURE TEMPS WILL FALL BELOW FREEZING
ACROSS MOST OF THE CWA. WILL EXPAND THE FREEZE WARNING.
MONDAY...HIGH PRESSURE WILL SLIDE TO THE EAST ACROSS THE CENTRAL
GREAT LAKES. WARM ADVECTION WILL RAMP UP ON THE BACKSIDE OF THE
HIGH AT THE SAME TIME AS MID AND HIGH CLOUDS SPILL OVER THE
MID-LEVEL RIDGE AXIS. AS A RESULT...WILL SEE A SLOW INCREASE OF
CLOUDS OVER THE COURSE OF THE DAY. AFTER 21Z...ENOUGH MOISTURE
ADVECTION LOOKS TO TAKE PLACE TO NEARLY SATURATE THE COLUMN OVER
CENTRAL AND NORTH-CENTRAL WISCONSIN. MID-LEVEL LAPSE RATES ARE VERY
POOR...BUT MID-LEVEL FGEN APPEARS SUFFICIENT FOR THE POSSIBILITY OF
SCATTERED LIGHT SHOWERS DEVELOPING. WILL INCREASE POPS INTO THE
40-50 PERCENT RANGE. THERE IS A FAIRLY LARGE RANGE IN GUIDANCE FOR
TEMPS TOMORROW AFTERNOON...BETWEEN THE COLD ECMWF AND WARM NAM.
SPLITTING THE DIFFERENCE SHOULD GET TEMPS CLOSE AND WILL GO WITH
HIGHS IN THE UPPER 50S TO LOW 60S BUT COOLER LAKE SIDE.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 232 PM CDT SUN MAY 12 2013
PCPN TRENDS MONDAY NIGHT INTO TUESDAY NIGHT...THE POTENTIAL FOR
SVR TSTMS TUESDAY NIGHT...GUSTY WINDS ON WEDNESDAY...PCPN TRENDS
NEXT WEEKEND...AND TEMPERATURES THROUGHOUT THE PERIOD ARE THE
MAIN FCST CONCERNS.
STRONG H8 WAA/MOISTURE CONVERGENCE WILL BRING A BAND OF SHOWERS THROUGH
THE AREA ON MONDAY NIGHT. ALTHOUGH THE RAIN WILL NOT LAST LONG AND QPF
AMOUNTS ARE EXPECTED TO BE LIGHT...FELT THAT POPS NEEDED TO BE RAISED
A LITTLE BIT. WAA/ISENT LIFT WILL CONTINUE ON TUESDAY AS A WARM FRONT
LIFTS INTO WISCONSIN. THIS FRONT IS EXPECTED TO MOVE INTO CENTRAL WI
LATE IN THE AFTERNOON. DESPITE SOME PERSISTENT FORCING...AN
INCREASINGLY CAPPED ATMOSPHERE AND LATE ARRIVAL OF THE INSTABILITY
AXIS PRECLUDES ADDING ANYTHING MORE THAN SLGT CHC/CHC POPS...MAINLY
OVER NORTHERN WI. TEMPERATURES WILL VARY GREATLY...WITH READINGS IN
THE MID 50S TO LOWER 60S NEAR THE LAKE...AND INLAND TEMPS RANGING
FROM THE UPPER 60S FAR NE WI TO THE LOWER TO MIDDLE 80S IN C WI.
THE WARM FRONT WILL LIFT NORTH TUESDAY...QUICKLY FOLLOWED BY THE COLD
FRONTAL PASSAGE DURING THE LATE EVENING AND OVERNIGHT HOURS. ELEVATED
CAPE OF 1500-2000 J/KG...VERY STEEP LAPSE RATES OF 7-8 C/KM...DEEP
LAYER SHEAR OF 40-50+ KTS AND 0-3 KM HELICITIES OF 400-500 WILL
PROVIDE PLENTY OF SUPPORT FOR SEVERE TSTMS...BUT CAPPING MAY BE
PROHIBITIVE FOR CONVECTIVE INITIATION. BEST CASE SCENARIO FROM THE
NAM AND A FEW OF THE SREF ENSEMBLE MEMBERS SHOW CINH OF 40-70
J/KG FOR A PARCEL LIFTED FROM THE 850-800 MB LEVEL OVER FAR
NORTHERN WI...BUT OTHER FCST SOUNDINGS SHOWED MUCH HIGHER CINH...
EVEN FROM ELEVATED PARCELS. WILL CONTINUE WITH CHC POPS TUESDAY
EVENING...AND A MENTION OF THE SVR TSTM POTENTIAL IN THE HAZARDOUS
WEATHER OUTLOOK...BUT HAVE TO ACKNOWLEDGE THE POTENTIAL FOR A MAINLY
DRY FCST. ANY PCPN THAT DOES DEVELOP WILL COME TO AN END OVERNIGHT
AS THE COLD FRONT SHIFTS EAST.
CAA...AN INCREASING NW PRESSURE GRADIENT AND DEEP MIXING WILL LEAD
TO A BREEZY/WINDY DAY ON WEDNESDAY. MIXING THROUGH 825-775 MB SUPPORTS
HIGH TEMPS IN THE LOWER TO MIDDLE 70S IN MOST LOCATIONS.
THE COLD FRONT WILL SETTLE SOUTH OF WISCONSIN FROM WEDNESDAY THROUGH
FRIDAY...AS ANOTHER COLD FRONT SAGS SOUTH OUT OF CANADA. WITH THE
REGION IN BETWEEN SYSTEMS...EXPECT A GENERALLY DRY PERIOD OVER THE
LATTER HALF OF THE WORK WEEK...WITH TEMPERATURES AT OR A LITTLE
ABOVE NORMAL.
LOW PRESSURE IS EXPECTED TO APPROACH FROM THE CENTRAL PLAINS THIS
WEEKEND...AND REACH THE IOWA VCNTY BY SUNDAY. AS THIS HAPPENS...
THE FRONT THAT STALLED TO OUR SOUTH WILL LIFT BACK INTO SOUTHERN
WISCONSIN...ALONG WITH ITS ASSOCIATED MOISTURE/ELEVATED INSTABILITY.
THIS SHOULD LEAD TO SHOWERS AND SCT TSTMS OVER THE REGION...ALONG
WITH COOLER TEMPERATURES DUE TO EAST WINDS AND ABUNDANT CLOUD COVER.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 636 PM CDT SUN MAY 12 2013
WHILE SURFACE WINDS DIMINISH EARLY THIS EVENING...NORTHWEST
WINDS TO 20 KTS AT 2000 FEET WILL LINGER FOR THE REST OF THE EVENING
FOR A PERIOD OF NEAR LLWS CONDITIONS. OTHERWISE VFR CONDITIONS
EXPECTED TONIGHT INTO MONDAY. THERE IS A CHANCE FOR SHOWERS LATE
IN THE DAY MONDAY OVER CENTRAL AND NORTH CENTRAL WISCONSIN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ020-022-030-
031-035>040-045-048>050-073-074.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TDH
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 228 PM CDT SAT MAY 11 2013
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE LOW
PRESSURE AND COLD FRONT ACROSS LOWER MICHIGAN THIS AFTERNOON.
BEHIND THE FRONT...A DEEP SHORTWAVE TROUGH COMBINED WITH STEEPENING
LOW LEVEL LAPSE RATES AND AMPLE LOW LEVEL MOISTURE ARE GENERATING
SCATTERED RAIN/SNOW/SLEET SHOWERS OVER EASTERN MINNESOTA TO CENTRAL
WISCONSIN...WHICH SHOULD ADVECT INTO EASTERN WISCONSIN LATER THIS
AFTERNOON. SOLID STRATUS DECK HAS HAD A DIFFICULT TIME ADVECTING
SOUTHWARD...BUT NOW EXTENDS FROM NORTHERN WISCONSIN TO HUDSON BAY.
STILL EXPECT THIS STRATUS DECK TO SAG SOUTH FOR THE REST OF THE
AFTERNOON...DRIVEN BY GUSTY NNW WINDS. FORECAST CONCERNS ARE
PRECIP TRENDS AND TEMPS...INCLUDING FROST/FREEZE HEADLINES.
TONIGHT...THE STRONG SHORTWAVE TROUGH WILL MOVE EAST OVER THE
CENTRAL GREAT LAKES THIS EVENING AND INTO FAR EASTERN ONTARIO
OVERNIGHT. BEHIND THE SHORTWAVE...A WIDESPREAD STRATUS DECK OVER
NORTHERN WISCONSIN AND ONTARIO SHOULD ADVECT SOUTH WITH THE HELP OF
MODERATELY STRONG NORTHERLY FLOW AND INCREASING INSTABILITY OF LAKE
SUPERIOR. WITH CYCLONIC FLOW AND COLD ADVECTION...TRENDED
CONSIDERABLY MORE CLOUDY WITH THE SKY COVER TONIGHT. STILL THINK
WILL SEE CLEARING SKIES AFTER MIDNIGHT OVER CENTRAL AND NORTHEAST
WISCONSIN AS MOISTURE IN THE COLUMN DRIES OUT. TEMPS THIS MORNING
OVER NORTHERN MINNESOTA WERE IN THE 32-34 DEGREE RANGE...WHICH WILL
BE THE AIRMASS ADVECTING INTO THE AREA TONIGHT. WITH NO CHANCE OF
DECOUPLING AND CLOUDS POTENTIALLY STICKING AROUND LONGER...HAVE
RAISED LOW TEMPS TOWARDS THE ECMWFBC GUIDANCE...WHICH IS USUALLY ONE
OF THE BETTER PERFORMING TEMP GUIDANCES. SINCE FROST IS A MINIMAL
CONCERN DUE TO WINDS REMAINING UP...HEADLINES ARE REALLY A FREEZE OR
NO FREEZE SCENARIO. WITH TEMPS ONLY BRIEFLY REACHING 32 DEGREES
LATE TONIGHT IN CENTRAL WISCONSIN...COORDINATION RESULTED IN A
DECISION TO GO WITH NO HEADLINES TONIGHT...BUT WILL STILL ADVISE
PEOPLE TO TAKE PRECAUTIONS WITH THEIR SENSITIVE PLANTS OVER CENTRAL
WISCONSIN IN THE HWO...IN CASE TEMPS DO FALL MORE THAN EXPECTED.
WILL GO WITH LOWS IN THE UPPER 20S NORTH...TO 32 DEGREES OVER
CENTRAL WISCONSIN...TO THE MID 30S NEAR LAKE MICHIGAN.
SUNDAY...LOW PRESSURE WILL MOVE FURTHER EAST INTO QUEBEC WHILE HIGH
PRESSURE BUILDS INTO THE REGION. THINK BROKEN CLOUD COVER WILL
CONTINUE TO RESIDE OVER NORTH-CENTRAL WISCONSIN TO START THE MORNING
WHICH SHOULD RETREAT TO THE NORTH. WITH DIURNAL HEATING
THOUGH...RATHER FLAT DIURNAL CU SHOULD DEVELOP BY LATE MORNING AND
THEN MIX OUT IN THE AFTERNOON. HIGHS TO TOP OUT IN THE MIDDLE 40S TO
LOWER 50S.
.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 228 PM CDT SAT MAY 11 2013
MAIN FCST CONCERNS INCLUDE FREEZE HEADLINES FOR SUNDAY NIGHT...THE
POTENTIAL FOR SEVERE TSTMS LATE TUESDAY INTO TUESDAY NIGHT...AND
TEMPERATURES THROUGH THE PERIOD.
SFC HIGH PRESSURE WILL RESIDE OVER THE FORECAST AREA ON SUNDAY NIGHT.
CLEAR SKIES AND LIGHT/CALM WINDS WILL ALLOW TEMPS TO DROP BLO FREEZING
ACROSS ALL BUT THE LAKESHORE AREAS. WE HAVE NOT STARTED UP FROST/FREEZE
HEADLINES OVER NORTHERN WI YET...SO NO HEADLINES THERE DESPITE MIN TEMPS
IN THE LOW TO MID 20S. WILL KEEP THE FREEZE WATCH GOING ACROSS THE
SOUTHERN HALF OF THE CWA...AND WOULD ANTICIPATE THAT THIS WILL BE
UPGRADED A FREEZE WARNING WITH THE 4 AM SUNDAY FCST PACKAGE.
AN UPPER LEVEL RIDGE WILL BUILD OVER THE REGION MONDAY INTO TUESDAY...
WITH LOW-LEVEL WAA KICKING IN MONDAY INTO MONDAY NIGHT. THE WAA SURGE
WILL BRING INCREASING CLOUDS...WITH A CHANCE OF SHOWERS OVER OUR WSTRN
COUNTIES ON MONDAY...AND OVER THE ENTIRE CWA MONDAY NIGHT.
ON TUESDAY...A WARM FRONT IS EXPECTED TO LIFT NORTHWARD INTO CENTRAL
WI DURING THE AFTERNOON. TEMPERATURES WILL BE A TOUGH CALL...AS CLOUDS
AND EAST WINDS NORTH OF THE FRONT COULD HOLD READINGS IN THE 50S/60S
OVER THE LAKESHORE AND FAR NE WI...WHILE MIXING THROUGH 850 MB OVER
CENTRAL WI WOULD BE SUPPORTIVE OF HIGHS IN THE UPPER 80S/LOWER 90S
IN THE FAR SW PART OF THE CWA. NOT CONFIDENT ENOUGH TO GO WITH THAT
LARGE OF A GRADIENT OVER THE FORECAST AREA...BUT WILL HAVE UPPER 50S/
LOWER 60S NEAR THE LAKE...WITH INLAND LOCATIONS RANGING FROM THE UPPER
60S OVER FAR NE WI TO THE LOWER 80S IN CENTRAL WI.
WILL CARRY A SLGT CHC/CHANCE OF TSTMS NORTH OF THE WARM FRONT ON
TUESDAY...AS THE MODELS SHOW A SURGE OF INSTABILITY ARRIVING DURING
THE AFTERNOON...BUT ALSO SOME POTENTIAL CAPPING. AM CONCERNED ABOUT
THE POTENTIAL FOR SVR TSTMS TUESDAY NIGHT...AS THE WARM FRONT LIFTS
NORTH...FOLLOWED BY THE COLD FRONTAL PASSAGE OVERNIGHT. MODELS ARE
IN DECENT AGREEMENT ON MUCAPE INCREASING TO 1500-2000 J/KG...
ALONG WITH DEEP LAYER SHEAR OF 45-55 KNOTS...0-3 KM HELICITIES OF
300-500...AND MID-LEVEL LAPSE RATES INCREASING TO 7-7.5 C/KM. THE
GFS MODEL SEEMS TO DEPICT THIS BEST...WITH A BULLSEYE OF QPF OVER
THE NE HALF OF THE FORECAST AREA. WILL ADD A MENTION OF POSSIBLE
SVR TSTMS LATE TUESDAY INTO TUESDAY NIGHT TO THE HAZARDOUS WEATHER
OUTLOOK.
THE COLD FRONT IS EXPECTED TO SHIFT SOUTH OF THE AREA WEDNESDAY INTO
THURSDAY NIGHT...RESULTING IN A GENERAL LULL IN THE PCPN. THE FRONT
WILL LIFT BACK TO THE NORTH LATE IN THE WEEK...BRINGING THE CHANCE
OF TSTMS BACK INTO THE REGION ON FRI/SAT.
ALTHOUGH TEMPERATURES WILL START OFF ON THE COOL SIDE...THEY SHOULD
AVERAGE ABOVE NORMAL FROM TUESDAY THROUGH SATURDAY.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1237 PM CDT SAT MAY 11 2013
A STRONG UPPER LEVEL DISTURBANCE WILL PASS ACROSS THE
AREA THROUGH THIS EVENING. WIDESPREAD LOW END VFR CIGS UPSTREAM
COMBINED WITH AFTERNOON INSTABILITY WILL LEAD TO ISOLATED TO
SCATTERED RAIN SHOWERS FROM EARLY THIS AFTERNOON THROUGH ABOUT
MID-EVENING. SNOW WILL LIKELY MIX IN WITH THE RAIN OVER N-C
WISCONSIN...WHICH COULD DROP VSBYS TO MVFR LEVELS.
OTHERWISE...GUSTY NW WINDS WILL PREVAIL UNTIL SUNSET. CLOUDS TO
STICK AROUND OVER N-C WISCONSIN FOR MUCH OF THE NIGHT AS FLOW WILL
REMAIN OFF LAKE SUPERIOR. NOT AS CLEAR CUT OVER CENTRAL AND
NORTHEAST WISCONSIN. SHARP CYCLONIC FLOW AND COLD LOW LEVEL
TEMPERATURES ARGUES FOR CLOUDS TO STICK AROUND LONGER THAN WHAT THE
MODELS SUGGEST. WILL TREND THAT DIRECTION...THOUGH CIGS SHOULD
REMAIN VFR. A STEADY WIND OF AROUND 10 KTS SHOULD PREVENT FROST
FROM FORMING THOUGH TEMPS WILL BE AROUND FREEZING. SCT-BKN CLOUD
COVER TOMORROW BUT NW WINDS WILL REMAIN GUSTY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR
WIZ020-030-031-035>040-045-048>050-073-074.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1234 PM CDT SAT MAY 11 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT SAT MAY 11 2013
MAIN FORECAST CONCERNS ARE ON WINDS TODAY...AND IF FROST OR FREEZE
CONDITIONS CAN OCCUR TONIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED STRONG RIDGING ALONG THE WEST COAST OF NORTH AMERICA AND A
SHARP/POTENT UPPER TROUGH DROPPING INTO NORTHERN MINNESOTA AND
NORTHWEST ONTARIO. A NARROW BAND OF SHOWERS CONTINUE ON RADAR
IMMEDIATELY AHEAD OF THE UPPER TROUGH...RESULTING FROM STRONG DPVA
AS WELL AS LOW LEVEL FRONTOGENETIC FORCING BEHIND A COLD FRONT. THIS
COLD FRONT EXTENDED FROM CENTRAL LAKE SUPERIOR TO WINONA MN AND DES
MOINES IA. PLENTY OF DRY AIR EXISTS BOTH AHEAD AND BEHIND THE COLD
FRONT...NOTED BY 00Z SOUNDINGS FROM MPX AND BIS. THE 00Z INL
SOUNDING WAS MOST REPRESENTATIVE OF THE ENVIRONMENT WITH THE NARROW
BAND OF SHOWERS...REFLECTING HIGH CLOUD BASES AND SATURATION MAINLY
FROM 750-550MB. THE HIGH CLOUD BASES COMBINED WITH THE LACK OF
MOISTURE KEEPING RAINFALL AMOUNTS VERY LOW WITH THE BAND OF SHOWERS.
AS EXPECTED WITH A HIGHLY AMPLIFIED UPPER TROUGH...A STRONG PRESSURE
RISE OF ALMOST 2 MB /1 HR WAS PRESENT BEHIND THE FRONT. THIS
PRESSURE RISE HAS RESULTED IN GUSTS OF 25-35 KT IMMEDIATELY AFTER
THE FRONTAL PASSAGE. A TIGHT PRESSURE GRADIENT EXISTS TOO BEHIND THE
FRONT...AHEAD OF CANADIAN HIGH PRESSURE IN SASKATCHEWAN. THE
BLUSTERY NORTHWEST WINDS ARE BRINGING UNSEASONABLY COOL AIR
SOUTHEAST...WITH 850MB TEMPS AT 00Z OF -5C AT THE PAS MANITOBA.
THE POTENT UPPER TROUGH APPROACHING THE FORECAST AREA IS PROGGED TO
ENCOMPASS MUCH OF THE WESTERN GREAT LAKES REGION BY THIS
EVENING...THEN BEGIN A SLOW MARCH EAST. THIS UPPER TROUGH WILL LEAD
TO A VARIETY OF CONCERNS FOR THE SHORT TERM PERIOD.
1. WINDS. AFTER THE COLD FRONT PASSES THROUGH THE REST OF THE
FORECAST AREA EARLY THIS MORNING...A TIGHT PRESSURE GRADIENT IS
PROGGED TO REMAIN IN PLACE PRETTY MUCH THROUGH TONIGHT. THE SURFACE
HIGH SEEN IN SASKATCHEWAN STAYS OFF WELL TO THE WEST...DROPPING DOWN
INTO SOUTHWEST MN BY 12Z SUNDAY. DEEP MIXING COMBINED WITH COLD
ADVECTION...A UNIDIRECTIONAL NORTHWEST FLOW AND STRONG SUBSIDENCE
FROM THE UPPER TROUGH CROSSING WILL RESULT IN A WINDY DAY TODAY.
WINDS AT THE TOP OF THE MIXED LAYER...AROUND 775MB...ONLY TOP OUT
AROUND 40 KT. MIXING THIS DOWN RESULTS IN MAX GUSTS IN THE 30-35 KT
RANGE...BELOW ADVISORY CRITERIA. WINDS ARE LIKELY TO DIMINISH THIS
EVENING WITH LOSS OF DAYTIME HEATING...BUT THERE IS NO CHANCE TO
DECOUPLE TONIGHT.
2. TEMPERATURES. 850MB TEMPS ARE PROGGED TO COOL TO AROUND -2C BY
18Z...OR 1.5-2 STANDARD DEVIATIONS BELOW NORMAL. AS MENTIONED IN THE
WINDS...THE STRONG MAY SUN WILL EASILY ALLOW MIXING UP TO 850MB AND
BEYOND...WHICH YIELDS HIGHS MAINLY IN THE LOW TO MID 50S. COLD
ADVECTION CONTINUES INTO TONIGHT AS 850MB TEMPS PLUNGE TO -4 TO -6C.
THE QUESTION IS IF THE WINDS MAY KEEP THE BOUNDARY LAYER MIXED
ENOUGH TO PREVENT TEMPERATURES FROM FALLING MUCH BELOW FREEZING. THE
11.00Z REGIONAL CANADIAN...ECMWF AND HIRES ARW KEEPS TEMPERATURES AT
OR ABOVE FREEZING ACROSS THE FORECAST AREA...WHEREAS THE 11.00Z NAM
HAS READINGS MORE IN THE 25 TO 30 RANGE. MOS GUIDANCE AND THE 11.00Z
GFS SPLIT THE DIFFERENCE AND KEEPS THE COLDEST TEMPERATURES OVER
CENTRAL WISCONSIN. TYPICALLY THE REGIONAL CANADIAN IS COLD FOR
LOWS...SO IT IS SURPRISING TO SEE IT BEING ONE OF THE WARMER MODELS.
GIVEN THE WIND...HAVE LEANED MORE TOWARDS THE 11.00Z GFS/HIRES ARW
AND REGIONAL CANADIAN IDEA. UPSTREAM OVER NORTH DAKOTA...
TEMPERATURES ARE STILL MOSTLY ABOVE FREEZING AS WELL AS OF 08Z.
3. FROST/FREEZE TONIGHT. VERY TRICKY AS NOTED BY THE TEMPERATURE
DISCUSSION ABOVE. WITH THE WIND AND DRY AIR ADVECTION TAKING PLACE
THROUGH TONIGHT...SEEMS HARD TO GET MUCH FROST DEVELOPMENT UNLESS
YOU ARE IN A REALLY SHELTERED LOCATION FROM THE NORTHWEST WIND.
RELATIVE HUMIDITIES LOOK TO STRUGGLE TO RISE TO 75 PERCENT. IN
ADDITION...WITH THE CONCERN ABOUT TEMPERATURES NOT FALLING BELOW
FREEZING...MAY NOT SEE FREEZE CONDITIONS EXCEPT PERHAPS IN TAYLOR
COUNTY. EVEN IF WE SEE FREEZE CONDITIONS...THEY MAY ONLY LAST AN
HOUR. THUS...HAVE NOT ISSUED ANY FROST/FREEZE HEADLINES FOR TONIGHT.
4. PRECIPITATION. ONGOING SHOWERS SHOULD PUSH SOUTHEAST OF THE AREA
BY 12Z THIS MORNING. UPSTREAM...THERE IS A CLUSTER OF CLOUDS ALONG
WITH A FEW SHOWERS AROUND THE GRAND FORKS AND FARGO AREAS OF NORTH
DAKOTA. THESE ARE ASSOCIATED WITH A SHORTWAVE WITHIN THE TROUGH.
GOOD MODEL AGREEMENT EXISTS OF THE SHORTWAVE AND CLOUDS DROPPING
THROUGH SOUTHERN MN AND NORTHERN IA TODAY. HAVE INCLUDED A FEW
SPRINKLES AS WELL AS THERE IS CONCERN THE SHOWERS MAY DRY UP SOME AS
HRRR RUNS SUGGEST. A FEW OTHER DIURNALLY DRIVEN SHOWERS/SPRINKLES
ASSOCIATED WITH THE COLD POOL MAY FORM TOO ACROSS TAYLOR/CLARK
COUNTIES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CDT SAT MAY 11 2013
SUNDAY THROUGH MONDAY NIGHT...THE UPPER RIDGE THAT HAS BEEN BUILDING
UP ALONG THE WEST COAT OF THE U.S. IS PROGGED BY ALL MODELS TO GET
PUSHED EAST DURING THIS PERIOD...IN RESPONSE TO A STRONG SHORTWAVE
COMING INTO THE PACIFIC NORTHWEST LATE MONDAY. THIS UPPER RIDGE WILL
HELP TO KEEP THIS PERIOD OF UNSEASONABLY COOL AIR BRIEF. BY LATE
SUNDAY NIGHT...WESTERN PORTIONS OF THE FORECAST AREA SHOULD START
GETTING INTO THE WARM ADVECTION SETUP. UNTIL THEN...MAIN CONCERN IS
FROST/FREEZE SUNDAY NIGHT. MODELS PROG THE SURFACE CANADIAN HIGH
PRESSURE RIDGE TO BE CENTERED OVER THE ENTIRE FORECAST AREA AT 06Z
MONDAY...LEADING TO CLEAR SKIES AND LIGHT WINDS. GIVEN A COOL SUNDAY
TO BEGIN WITH...SITUATION SHOULD BE VERY FAVORABLE FOR FROST/FREEZE
CONDITIONS ACROSS MUCH OF THE FORECAST AREA...ESPECIALLY OVER
WISCONSIN. LEANED TOWARDS THE COOLER SIDE OF GUIDANCE FOR LOWS...
RESULTING IN THE NEED FOR A FREEZE WATCH FOR COUNTIES ALONG AND
NORTHEAST OF I-94. THE WARM ADVECTION MONDAY INTO MONDAY NIGHT IS
INTERESTING AS 850MB TEMPS CLIMB ABOUT 12C FROM 12Z MONDAY TO 12Z
TUESDAY. GOOD MODEL AGREEMENT EXISTS THAT AN AREA OF MID AND HIGH
CLOUDS WILL DEVELOP IN RESPONSE TO THIS WARM ADVECTION. ISENTROPIC
LIFT FIELDS ON THE 295 AND 300K SURFACE SHOW AN AREA OF LIFT
OCCURRING WITHIN THESE CLOUDS...MARCHING EAST WITH TIME. THE 11.00Z
GFS/ECMWF AND 11.03Z SREF ALL DEVELOP PRECIPITATION...WHILE THE
11.00Z NAM IS DRY. THE NAM DOES NOT DEVELOP PRECIPITATION BECAUSE OF
DRY LOW LEVELS ABSORBING THE RAIN...WHICH THE NAM TENDS TO OVERDO.
THUS...HAVE KEPT AND RAISED SLIGHTLY THE PRECIPITATION CHANCES FOR
MONDAY AFTERNOON AND EVENING. DID TAKE OUT THE THUNDER...THOUGH...AS
NO INSTABILITY EXISTS.
FOR THE REST OF THE WEEK...
FOCUS REMAINS ON HIGH TEMPERATURES ON TUESDAY. 11.00Z CANADIAN AND
ECMWF HAVE WENT BACK AND NOW SHOW A SURFACE WARM FRONT PROGRESSING
THROUGH THE AREA QUICKER...WHICH ALLOWS WARMER AIR TO PUSH INTO THE
AREA DURING THE DAY. THE 11.00Z GFS HAS STAYED PERSISTENT. ALL
MODELS NOW SHOW 850MB TEMPS CLIMBING TO 18C OVER CENTRAL WISCONSIN
TO 24C NEAR I-35 BY 00Z...WHICH ARE 2.5 STANDARD DEVIATIONS ABOVE
NORMAL. ONCE YOU GET TO 2.5...CONCERN INCREASES OF REACHING RECORDS.
PROBLEM IS MOST MODEL GUIDANCE HAS TOO MUCH MOISTURE IN THE BOUNDARY
LAYER. THE SCENARIO IS THE GULF OF MEXICO IS CUT OFF BY THE CURRENT
CANADIAN HIGH DROPPING DOWN TO THE GULF COAST...AND CROPS THAT ARE
BEHIND SCHEDULE DUE TO THE COOL SPRING. MODELS ARE TRYING TO GET THE
MOISTURE FROM EVAPOTRANSPORATION. WITH TOO MUCH MOISTURE IN THE
BOUNDARY LAYER...TEMPERATURES CANNOT RISE ENOUGH FROM MIXING.
THUS...HAVE STAYED PRETTY CLOSE TO THE PREVIOUS FORECAST AND BOOSTED
READINGS A FEW DEGREES WEST OF THE MISSISSIPPI RIVER TO ACCOUNT FOR
THE GROWING CONSENSUS ON THE WARM AIR TIMING. TEMPERATURES MAY STILL
NEED TO BE RAISED FURTHER.
A COLD FRONT ACCOMPANYING THAT TROUGH COMING INTO THE PACIFIC
NORTHWEST MONDAY IS SLATED TO COME THROUGH THE FORECAST AREA TUESDAY
NIGHT AND WEDNESDAY. FOLLOWED A CONSENSUS BLEND AND HAVE JUST LOW
CHANCES FOR SHOWERS/STORMS AS THE FRONT MOVES THROUGH. BEYOND
WEDNESDAY...THE FORECAST GETS MUDDLED WITH THE 11.00Z ECMWF/CANADIAN
SUGGESTING MORE OF A ZONAL TO SLIGHT UPPER RIDGING PATTERN IN PLACE
AS TROUGHING REFORMS IN THE PACIFIC NORTHWEST. MEANWHILE...THE
11.00Z GFS/GFS ENSEMBLES DEPICT TROUGHING TO FORM AND LINGER AROUND
THE FORECAST AREA. BOTH SITUATIONS SUGGEST A TREND TOWARDS
DRIER...AND THEREFORE THE CHANCES OF PRECIPITATION HAVE BEEN LOWERED
SOME. COULD SEE FINE TUNING TAKING PLACE TO DRY OUT PORTIONS OF THE
WEDNESDAY NIGHT THROUGH FRIDAY PERIOD. OTHERWISE...TEMPERATURES LOOK
COOLER BUT SHOULD STILL STAY NEAR OR ABOVE NORMAL WITH A MOSTLY
PACIFIC FLOW OF AIR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1234 PM CDT SAT MAY 11 2013
COLDER TEMPERATURES ALOFT COMBINED WITH SOME RESIDUAL LOW LEVEL
MOISTURE WILL RESULT IN ISOLATED TO WDLY SCT SHRA/SHPL THRU THE
EARLY AFTERNOON HOURS TODAY. GIVEN SPOTTY NATURE AND FAST MOVEMENT
OF THESE SHOWERS...ONLY INCLUDED VCSH IN TAFS. THIS MOISTURE WILL
EXIT LATER THIS AFTERNOON...WITH FURTHER DRYING/SUBSIDENCE AND HIGH
PRESSURE BUILDING PRODUCING SKC FOR TONIGHT/SUNDAY. PRESSURE
GRADIENT AND MIXING WILL RESULT IN CONTINUED STRONG/GUSTY NORTHWEST
WINDS INTO EARLY THIS EVENING. WITH LOSS OF DAYTIME HEATING AND
RELAXING OF THE GRADIENT...WINDS TONIGHT/SUN WILL MOSTLY BE IN THE
10-15KT RANGE.
&&
.FIRE WEATHER...
ISSUED AT 343 AM CDT SAT MAY 11 2013
BREEZY NORTHWEST WINDS ARE EXPECTED THIS WEEKEND AHEAD OF A
STRONG AREA OF CANADIAN HIGH PRESSURE OVER SASKATCHEWAN DROPPING
SOUTHEASTWARD. THESE NORTHWEST WINDS ARE GOING TO USHER IN AN
UNSEASONABLY COOL AND DRY AIRMASS INTO THE FORECAST AREA. DEEP
MIXING RESULTING FROM THE STRONG MAY SUN SHOULD ALLOW DEWPOINTS TO
DROP INTO THE MID TEENS TO MID 20S DURING THE AFTERNOON...WHICH
WITH HIGH TEMPERATURES IN THE LOW TO MID 50S...RELATIVE HUMIDITIES
WILL DROP TO 20 TO 30 PERCENT. PRECLUDING A RED FLAG WARNING AT
THIS TIME IS A COMBINATION OF THE COOL TEMPERATURES...THE RECENT
SOAKING RAIN ON THURSDAY RESULTING IN WETTER FUELS...AND GREEN
UP THAT REALLY TOOK OFF THIS WEEK.
HEADING INTO EARLY NEXT WEEK...FOCUS REMAINS ON TUESDAY AS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA BECOME POSITIONED IN A VERY
WARM ENVIRONMENT. TEMPERATURES LOOK TO CLIMB INTO THE MID TO UPPER
80S...AND PERHAPS COULD EVEN CLIMB INTO THE LOW 90S. DEWPOINT
FORECASTS ARE A LITTLE DIFFICULT AT THIS TIME WITH MOST MODELS
APPEARING TO OVERDO THEM...BUT RELATIVE HUMIDITIES SHOULD DROP AT
LEAST TO 35 TO 40 PERCENT. IT IS POSSIBLE THESE COULD END UP LOWER
AS CERTAINTY ON DEWPOINTS INCREASES. WINDS LOOK MARGINAL RIGHT
NOW FOR RED FLAG CONDITIONS. NEEDLESS TO SAY...SOMETHING TO KEEP
AN EYE ON OVER THE NEXT FEW DAYS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR
WIZ017-029-034-042>044.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM.....AJ
LONG TERM......AJ
AVIATION.......RRS
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
557 AM CDT SAT MAY 11 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT SAT MAY 11 2013
MAIN FORECAST CONCERNS ARE ON WINDS TODAY...AND IF FROST OR FREEZE
CONDITIONS CAN OCCUR TONIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED STRONG RIDGING ALONG THE WEST COAST OF NORTH AMERICA AND A
SHARP/POTENT UPPER TROUGH DROPPING INTO NORTHERN MINNESOTA AND
NORTHWEST ONTARIO. A NARROW BAND OF SHOWERS CONTINUE ON RADAR
IMMEDIATELY AHEAD OF THE UPPER TROUGH...RESULTING FROM STRONG DPVA
AS WELL AS LOW LEVEL FRONTOGENETIC FORCING BEHIND A COLD FRONT. THIS
COLD FRONT EXTENDED FROM CENTRAL LAKE SUPERIOR TO WINONA MN AND DES
MOINES IA. PLENTY OF DRY AIR EXISTS BOTH AHEAD AND BEHIND THE COLD
FRONT...NOTED BY 00Z SOUNDINGS FROM MPX AND BIS. THE 00Z INL
SOUNDING WAS MOST REPRESENTATIVE OF THE ENVIRONMENT WITH THE NARROW
BAND OF SHOWERS...REFLECTING HIGH CLOUD BASES AND SATURATION MAINLY
FROM 750-550MB. THE HIGH CLOUD BASES COMBINED WITH THE LACK OF
MOISTURE KEEPING RAINFALL AMOUNTS VERY LOW WITH THE BAND OF SHOWERS.
AS EXPECTED WITH A HIGHLY AMPLIFIED UPPER TROUGH...A STRONG PRESSURE
RISE OF ALMOST 2 MB /1 HR WAS PRESENT BEHIND THE FRONT. THIS
PRESSURE RISE HAS RESULTED IN GUSTS OF 25-35 KT IMMEDIATELY AFTER
THE FRONTAL PASSAGE. A TIGHT PRESSURE GRADIENT EXISTS TOO BEHIND THE
FRONT...AHEAD OF CANADIAN HIGH PRESSURE IN SASKATCHEWAN. THE
BLUSTERY NORTHWEST WINDS ARE BRINGING UNSEASONABLY COOL AIR
SOUTHEAST...WITH 850MB TEMPS AT 00Z OF -5C AT THE PAS MANITOBA.
THE POTENT UPPER TROUGH APPROACHING THE FORECAST AREA IS PROGGED TO
ENCOMPASS MUCH OF THE WESTERN GREAT LAKES REGION BY THIS
EVENING...THEN BEGIN A SLOW MARCH EAST. THIS UPPER TROUGH WILL LEAD
TO A VARIETY OF CONCERNS FOR THE SHORT TERM PERIOD.
1. WINDS. AFTER THE COLD FRONT PASSES THROUGH THE REST OF THE
FORECAST AREA EARLY THIS MORNING...A TIGHT PRESSURE GRADIENT IS
PROGGED TO REMAIN IN PLACE PRETTY MUCH THROUGH TONIGHT. THE SURFACE
HIGH SEEN IN SASKATCHEWAN STAYS OFF WELL TO THE WEST...DROPPING DOWN
INTO SOUTHWEST MN BY 12Z SUNDAY. DEEP MIXING COMBINED WITH COLD
ADVECTION...A UNIDIRECTIONAL NORTHWEST FLOW AND STRONG SUBSIDENCE
FROM THE UPPER TROUGH CROSSING WILL RESULT IN A WINDY DAY TODAY.
WINDS AT THE TOP OF THE MIXED LAYER...AROUND 775MB...ONLY TOP OUT
AROUND 40 KT. MIXING THIS DOWN RESULTS IN MAX GUSTS IN THE 30-35 KT
RANGE...BELOW ADVISORY CRITERIA. WINDS ARE LIKELY TO DIMINISH THIS
EVENING WITH LOSS OF DAYTIME HEATING...BUT THERE IS NO CHANCE TO
DECOUPLE TONIGHT.
2. TEMPERATURES. 850MB TEMPS ARE PROGGED TO COOL TO AROUND -2C BY
18Z...OR 1.5-2 STANDARD DEVIATIONS BELOW NORMAL. AS MENTIONED IN THE
WINDS...THE STRONG MAY SUN WILL EASILY ALLOW MIXING UP TO 850MB AND
BEYOND...WHICH YIELDS HIGHS MAINLY IN THE LOW TO MID 50S. COLD
ADVECTION CONTINUES INTO TONIGHT AS 850MB TEMPS PLUNGE TO -4 TO -6C.
THE QUESTION IS IF THE WINDS MAY KEEP THE BOUNDARY LAYER MIXED
ENOUGH TO PREVENT TEMPERATURES FROM FALLING MUCH BELOW FREEZING. THE
11.00Z REGIONAL CANADIAN...ECMWF AND HIRES ARW KEEPS TEMPERATURES AT
OR ABOVE FREEZING ACROSS THE FORECAST AREA...WHEREAS THE 11.00Z NAM
HAS READINGS MORE IN THE 25 TO 30 RANGE. MOS GUIDANCE AND THE 11.00Z
GFS SPLIT THE DIFFERENCE AND KEEPS THE COLDEST TEMPERATURES OVER
CENTRAL WISCONSIN. TYPICALLY THE REGIONAL CANADIAN IS COLD FOR
LOWS...SO IT IS SURPRISING TO SEE IT BEING ONE OF THE WARMER MODELS.
GIVEN THE WIND...HAVE LEANED MORE TOWARDS THE 11.00Z GFS/HIRES ARW
AND REGIONAL CANADIAN IDEA. UPSTREAM OVER NORTH DAKOTA...
TEMPERATURES ARE STILL MOSTLY ABOVE FREEZING AS WELL AS OF 08Z.
3. FROST/FREEZE TONIGHT. VERY TRICKY AS NOTED BY THE TEMPERATURE
DISCUSSION ABOVE. WITH THE WIND AND DRY AIR ADVECTION TAKING PLACE
THROUGH TONIGHT...SEEMS HARD TO GET MUCH FROST DEVELOPMENT UNLESS
YOU ARE IN A REALLY SHELTERED LOCATION FROM THE NORTHWEST WIND.
RELATIVE HUMIDITIES LOOK TO STRUGGLE TO RISE TO 75 PERCENT. IN
ADDITION...WITH THE CONCERN ABOUT TEMPERATURES NOT FALLING BELOW
FREEZING...MAY NOT SEE FREEZE CONDITIONS EXCEPT PERHAPS IN TAYLOR
COUNTY. EVEN IF WE SEE FREEZE CONDITIONS...THEY MAY ONLY LAST AN
HOUR. THUS...HAVE NOT ISSUED ANY FROST/FREEZE HEADLINES FOR TONIGHT.
4. PRECIPITATION. ONGOING SHOWERS SHOULD PUSH SOUTHEAST OF THE AREA
BY 12Z THIS MORNING. UPSTREAM...THERE IS A CLUSTER OF CLOUDS ALONG
WITH A FEW SHOWERS AROUND THE GRAND FORKS AND FARGO AREAS OF NORTH
DAKOTA. THESE ARE ASSOCIATED WITH A SHORTWAVE WITHIN THE TROUGH.
GOOD MODEL AGREEMENT EXISTS OF THE SHORTWAVE AND CLOUDS DROPPING
THROUGH SOUTHERN MN AND NORTHERN IA TODAY. HAVE INCLUDED A FEW
SPRINKLES AS WELL AS THERE IS CONCERN THE SHOWERS MAY DRY UP SOME AS
HRRR RUNS SUGGEST. A FEW OTHER DIURNALLY DRIVEN SHOWERS/SPRINKLES
ASSOCIATED WITH THE COLD POOL MAY FORM TOO ACROSS TAYLOR/CLARK
COUNTIES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CDT SAT MAY 11 2013
SUNDAY THROUGH MONDAY NIGHT...THE UPPER RIDGE THAT HAS BEEN BUILDING
UP ALONG THE WEST COAT OF THE U.S. IS PROGGED BY ALL MODELS TO GET
PUSHED EAST DURING THIS PERIOD...IN RESPONSE TO A STRONG SHORTWAVE
COMING INTO THE PACIFIC NORTHWEST LATE MONDAY. THIS UPPER RIDGE WILL
HELP TO KEEP THIS PERIOD OF UNSEASONABLY COOL AIR BRIEF. BY LATE
SUNDAY NIGHT...WESTERN PORTIONS OF THE FORECAST AREA SHOULD START
GETTING INTO THE WARM ADVECTION SETUP. UNTIL THEN...MAIN CONCERN IS
FROST/FREEZE SUNDAY NIGHT. MODELS PROG THE SURFACE CANADIAN HIGH
PRESSURE RIDGE TO BE CENTERED OVER THE ENTIRE FORECAST AREA AT 06Z
MONDAY...LEADING TO CLEAR SKIES AND LIGHT WINDS. GIVEN A COOL SUNDAY
TO BEGIN WITH...SITUATION SHOULD BE VERY FAVORABLE FOR FROST/FREEZE
CONDITIONS ACROSS MUCH OF THE FORECAST AREA...ESPECIALLY OVER
WISCONSIN. LEANED TOWARDS THE COOLER SIDE OF GUIDANCE FOR LOWS...
RESULTING IN THE NEED FOR A FREEZE WATCH FOR COUNTIES ALONG AND
NORTHEAST OF I-94. THE WARM ADVECTION MONDAY INTO MONDAY NIGHT IS
INTERESTING AS 850MB TEMPS CLIMB ABOUT 12C FROM 12Z MONDAY TO 12Z
TUESDAY. GOOD MODEL AGREEMENT EXISTS THAT AN AREA OF MID AND HIGH
CLOUDS WILL DEVELOP IN RESPONSE TO THIS WARM ADVECTION. ISENTROPIC
LIFT FIELDS ON THE 295 AND 300K SURFACE SHOW AN AREA OF LIFT
OCCURRING WITHIN THESE CLOUDS...MARCHING EAST WITH TIME. THE 11.00Z
GFS/ECMWF AND 11.03Z SREF ALL DEVELOP PRECIPITATION...WHILE THE
11.00Z NAM IS DRY. THE NAM DOES NOT DEVELOP PRECIPITATION BECAUSE OF
DRY LOW LEVELS ABSORBING THE RAIN...WHICH THE NAM TENDS TO OVERDO.
THUS...HAVE KEPT AND RAISED SLIGHTLY THE PRECIPITATION CHANCES FOR
MONDAY AFTERNOON AND EVENING. DID TAKE OUT THE THUNDER...THOUGH...AS
NO INSTABILITY EXISTS.
FOR THE REST OF THE WEEK...
FOCUS REMAINS ON HIGH TEMPERATURES ON TUESDAY. 11.00Z CANADIAN AND
ECMWF HAVE WENT BACK AND NOW SHOW A SURFACE WARM FRONT PROGRESSING
THROUGH THE AREA QUICKER...WHICH ALLOWS WARMER AIR TO PUSH INTO THE
AREA DURING THE DAY. THE 11.00Z GFS HAS STAYED PERSISTENT. ALL
MODELS NOW SHOW 850MB TEMPS CLIMBING TO 18C OVER CENTRAL WISCONSIN
TO 24C NEAR I-35 BY 00Z...WHICH ARE 2.5 STANDARD DEVIATIONS ABOVE
NORMAL. ONCE YOU GET TO 2.5...CONCERN INCREASES OF REACHING RECORDS.
PROBLEM IS MOST MODEL GUIDANCE HAS TOO MUCH MOISTURE IN THE BOUNDARY
LAYER. THE SCENARIO IS THE GULF OF MEXICO IS CUT OFF BY THE CURRENT
CANADIAN HIGH DROPPING DOWN TO THE GULF COAST...AND CROPS THAT ARE
BEHIND SCHEDULE DUE TO THE COOL SPRING. MODELS ARE TRYING TO GET THE
MOISTURE FROM EVAPOTRANSPORATION. WITH TOO MUCH MOISTURE IN THE
BOUNDARY LAYER...TEMPERATURES CANNOT RISE ENOUGH FROM MIXING.
THUS...HAVE STAYED PRETTY CLOSE TO THE PREVIOUS FORECAST AND BOOSTED
READINGS A FEW DEGREES WEST OF THE MISSISSIPPI RIVER TO ACCOUNT FOR
THE GROWING CONSENSUS ON THE WARM AIR TIMING. TEMPERATURES MAY STILL
NEED TO BE RAISED FURTHER.
A COLD FRONT ACCOMPANYING THAT TROUGH COMING INTO THE PACIFIC
NORTHWEST MONDAY IS SLATED TO COME THROUGH THE FORECAST AREA TUESDAY
NIGHT AND WEDNESDAY. FOLLOWED A CONSENSUS BLEND AND HAVE JUST LOW
CHANCES FOR SHOWERS/STORMS AS THE FRONT MOVES THROUGH. BEYOND
WEDNESDAY...THE FORECAST GETS MUDDLED WITH THE 11.00Z ECMWF/CANADIAN
SUGGESTING MORE OF A ZONAL TO SLIGHT UPPER RIDGING PATTERN IN PLACE
AS TROUGHING REFORMS IN THE PACIFIC NORTHWEST. MEANWHILE...THE
11.00Z GFS/GFS ENSEMBLES DEPICT TROUGHING TO FORM AND LINGER AROUND
THE FORECAST AREA. BOTH SITUATIONS SUGGEST A TREND TOWARDS
DRIER...AND THEREFORE THE CHANCES OF PRECIPITATION HAVE BEEN LOWERED
SOME. COULD SEE FINE TUNING TAKING PLACE TO DRY OUT PORTIONS OF THE
WEDNESDAY NIGHT THROUGH FRIDAY PERIOD. OTHERWISE...TEMPERATURES LOOK
COOLER BUT SHOULD STILL STAY NEAR OR ABOVE NORMAL WITH A MOSTLY
PACIFIC FLOW OF AIR.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 556 AM CDT SAT MAY 11 2013
MAIN CONCERN WILL BE GUSTY POST-COLD FRONTAL NORTHWEST WINDS TODAY
INTO EARLY THIS EVENING. PLAN ON SUSTAINED WINDS IN THE 20-25KT
RANGE WITH GUSTS AROUND 35KT. LOOK FOR THESE WINDS TO SUBSIDE TO
10KT OR LESS AFTER 03Z THIS EVENING. OTHERWISE...SCT-BKN CUMULUS
EXPECTED TODAY WITH BASES AOA 4KFT. LOOK FOR THESE CLOUDS TO
DISSIPATE ALSO WITH SUNSET...WITH SKIES BECOMING CLEAR THROUGH THE
OVERNIGHT HOURS.
&&
.FIRE WEATHER...
ISSUED AT 343 AM CDT SAT MAY 11 2013
BREEZY NORTHWEST WINDS ARE EXPECTED THIS WEEKEND AHEAD OF A
STRONG AREA OF CANADIAN HIGH PRESSURE OVER SASKATCHEWAN DROPPING
SOUTHEASTWARD. THESE NORTHWEST WINDS ARE GOING TO USHER IN AN
UNSEASONABLY COOL AND DRY AIRMASS INTO THE FORECAST AREA. DEEP
MIXING RESULTING FROM THE STRONG MAY SUN SHOULD ALLOW DEWPOINTS TO
DROP INTO THE MID TEENS TO MID 20S DURING THE AFTERNOON...WHICH
WITH HIGH TEMPERATURES IN THE LOW TO MID 50S...RELATIVE HUMIDITIES
WILL DROP TO 20 TO 30 PERCENT. PRECLUDING A RED FLAG WARNING AT
THIS TIME IS A COMBINATION OF THE COOL TEMPERATURES...THE RECENT
SOAKING RAIN ON THURSDAY RESULTING IN WETTER FUELS...AND GREEN
UP THAT REALLY TOOK OFF THIS WEEK.
HEADING INTO EARLY NEXT WEEK...FOCUS REMAINS ON TUESDAY AS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA BECOME POSITIONED IN A VERY
WARM ENVIRONMENT. TEMPERATURES LOOK TO CLIMB INTO THE MID TO UPPER
80S...AND PERHAPS COULD EVEN CLIMB INTO THE LOW 90S. DEWPOINT
FORECASTS ARE A LITTLE DIFFICULT AT THIS TIME WITH MOST MODELS
APPEARING TO OVERDO THEM...BUT RELATIVE HUMIDITIES SHOULD DROP AT
LEAST TO 35 TO 40 PERCENT. IT IS POSSIBLE THESE COULD END UP LOWER
AS CERTAINTY ON DEWPOINTS INCREASES. WINDS LOOK MARGINAL RIGHT
NOW FOR RED FLAG CONDITIONS. NEEDLESS TO SAY...SOMETHING TO KEEP
AN EYE ON OVER THE NEXT FEW DAYS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR
WIZ017-029-034-042>044.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
344 AM CDT SAT MAY 11 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT SAT MAY 11 2013
MAIN FORECAST CONCERNS ARE ON WINDS TODAY...AND IF FROST OR FREEZE
CONDITIONS CAN OCCUR TONIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED STRONG RIDGING ALONG THE WEST COAST OF NORTH AMERICA AND A
SHARP/POTENT UPPER TROUGH DROPPING INTO NORTHERN MINNESOTA AND
NORTHWEST ONTARIO. A NARROW BAND OF SHOWERS CONTINUE ON RADAR
IMMEDIATELY AHEAD OF THE UPPER TROUGH...RESULTING FROM STRONG DPVA
AS WELL AS LOW LEVEL FRONTOGENETIC FORCING BEHIND A COLD FRONT. THIS
COLD FRONT EXTENDED FROM CENTRAL LAKE SUPERIOR TO WINONA MN AND DES
MOINES IA. PLENTY OF DRY AIR EXISTS BOTH AHEAD AND BEHIND THE COLD
FRONT...NOTED BY 00Z SOUNDINGS FROM MPX AND BIS. THE 00Z INL
SOUNDING WAS MOST REPRESENTATIVE OF THE ENVIRONMENT WITH THE NARROW
BAND OF SHOWERS...REFLECTING HIGH CLOUD BASES AND SATURATION MAINLY
FROM 750-550MB. THE HIGH CLOUD BASES COMBINED WITH THE LACK OF
MOISTURE KEEPING RAINFALL AMOUNTS VERY LOW WITH THE BAND OF SHOWERS.
AS EXPECTED WITH A HIGHLY AMPLIFIED UPPER TROUGH...A STRONG PRESSURE
RISE OF ALMOST 2 MB /1 HR WAS PRESENT BEHIND THE FRONT. THIS
PRESSURE RISE HAS RESULTED IN GUSTS OF 25-35 KT IMMEDIATELY AFTER
THE FRONTAL PASSAGE. A TIGHT PRESSURE GRADIENT EXISTS TOO BEHIND THE
FRONT...AHEAD OF CANADIAN HIGH PRESSURE IN SASKATCHEWAN. THE
BLUSTERY NORTHWEST WINDS ARE BRINGING UNSEASONABLY COOL AIR
SOUTHEAST...WITH 850MB TEMPS AT 00Z OF -5C AT THE PAS MANITOBA.
THE POTENT UPPER TROUGH APPROACHING THE FORECAST AREA IS PROGGED TO
ENCOMPASS MUCH OF THE WESTERN GREAT LAKES REGION BY THIS
EVENING...THEN BEGIN A SLOW MARCH EAST. THIS UPPER TROUGH WILL LEAD
TO A VARIETY OF CONCERNS FOR THE SHORT TERM PERIOD.
1. WINDS. AFTER THE COLD FRONT PASSES THROUGH THE REST OF THE
FORECAST AREA EARLY THIS MORNING...A TIGHT PRESSURE GRADIENT IS
PROGGED TO REMAIN IN PLACE PRETTY MUCH THROUGH TONIGHT. THE SURFACE
HIGH SEEN IN SASKATCHEWAN STAYS OFF WELL TO THE WEST...DROPPING DOWN
INTO SOUTHWEST MN BY 12Z SUNDAY. DEEP MIXING COMBINED WITH COLD
ADVECTION...A UNIDIRECTIONAL NORTHWEST FLOW AND STRONG SUBSIDENCE
FROM THE UPPER TROUGH CROSSING WILL RESULT IN A WINDY DAY TODAY.
WINDS AT THE TOP OF THE MIXED LAYER...AROUND 775MB...ONLY TOP OUT
AROUND 40 KT. MIXING THIS DOWN RESULTS IN MAX GUSTS IN THE 30-35 KT
RANGE...BELOW ADVISORY CRITERIA. WINDS ARE LIKELY TO DIMINISH THIS
EVENING WITH LOSS OF DAYTIME HEATING...BUT THERE IS NO CHANCE TO
DECOUPLE TONIGHT.
2. TEMPERATURES. 850MB TEMPS ARE PROGGED TO COOL TO AROUND -2C BY
18Z...OR 1.5-2 STANDARD DEVIATIONS BELOW NORMAL. AS MENTIONED IN THE
WINDS...THE STRONG MAY SUN WILL EASILY ALLOW MIXING UP TO 850MB AND
BEYOND...WHICH YIELDS HIGHS MAINLY IN THE LOW TO MID 50S. COLD
ADVECTION CONTINUES INTO TONIGHT AS 850MB TEMPS PLUNGE TO -4 TO -6C.
THE QUESTION IS IF THE WINDS MAY KEEP THE BOUNDARY LAYER MIXED
ENOUGH TO PREVENT TEMPERATURES FROM FALLING MUCH BELOW FREEZING. THE
11.00Z REGIONAL CANADIAN...ECMWF AND HIRES ARW KEEPS TEMPERATURES AT
OR ABOVE FREEZING ACROSS THE FORECAST AREA...WHEREAS THE 11.00Z NAM
HAS READINGS MORE IN THE 25 TO 30 RANGE. MOS GUIDANCE AND THE 11.00Z
GFS SPLIT THE DIFFERENCE AND KEEPS THE COLDEST TEMPERATURES OVER
CENTRAL WISCONSIN. TYPICALLY THE REGIONAL CANADIAN IS COLD FOR
LOWS...SO IT IS SURPRISING TO SEE IT BEING ONE OF THE WARMER MODELS.
GIVEN THE WIND...HAVE LEANED MORE TOWARDS THE 11.00Z GFS/HIRES ARW
AND REGIONAL CANADIAN IDEA. UPSTREAM OVER NORTH DAKOTA...
TEMPERATURES ARE STILL MOSTLY ABOVE FREEZING AS WELL AS OF 08Z.
3. FROST/FREEZE TONIGHT. VERY TRICKY AS NOTED BY THE TEMPERATURE
DISCUSSION ABOVE. WITH THE WIND AND DRY AIR ADVECTION TAKING PLACE
THROUGH TONIGHT...SEEMS HARD TO GET MUCH FROST DEVELOPMENT UNLESS
YOU ARE IN A REALLY SHELTERED LOCATION FROM THE NORTHWEST WIND.
RELATIVE HUMIDITIES LOOK TO STRUGGLE TO RISE TO 75 PERCENT. IN
ADDITION...WITH THE CONCERN ABOUT TEMPERATURES NOT FALLING BELOW
FREEZING...MAY NOT SEE FREEZE CONDITIONS EXCEPT PERHAPS IN TAYLOR
COUNTY. EVEN IF WE SEE FREEZE CONDITIONS...THEY MAY ONLY LAST AN
HOUR. THUS...HAVE NOT ISSUED ANY FROST/FREEZE HEADLINES FOR TONIGHT.
4. PRECIPITATION. ONGOING SHOWERS SHOULD PUSH SOUTHEAST OF THE AREA
BY 12Z THIS MORNING. UPSTREAM...THERE IS A CLUSTER OF CLOUDS ALONG
WITH A FEW SHOWERS AROUND THE GRAND FORKS AND FARGO AREAS OF NORTH
DAKOTA. THESE ARE ASSOCIATED WITH A SHORTWAVE WITHIN THE TROUGH.
GOOD MODEL AGREEMENT EXISTS OF THE SHORTWAVE AND CLOUDS DROPPING
THROUGH SOUTHERN MN AND NORTHERN IA TODAY. HAVE INCLUDED A FEW
SPRINKLES AS WELL AS THERE IS CONCERN THE SHOWERS MAY DRY UP SOME AS
HRRR RUNS SUGGEST. A FEW OTHER DIURNALLY DRIVEN SHOWERS/SPRINKLES
ASSOCIATED WITH THE COLD POOL MAY FORM TOO ACROSS TAYLOR/CLARK
COUNTIES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CDT SAT MAY 11 2013
SUNDAY THROUGH MONDAY NIGHT...THE UPPER RIDGE THAT HAS BEEN BUILDING
UP ALONG THE WEST COAT OF THE U.S. IS PROGGED BY ALL MODELS TO GET
PUSHED EAST DURING THIS PERIOD...IN RESPONSE TO A STRONG SHORTWAVE
COMING INTO THE PACIFIC NORTHWEST LATE MONDAY. THIS UPPER RIDGE WILL
HELP TO KEEP THIS PERIOD OF UNSEASONABLY COOL AIR BRIEF. BY LATE
SUNDAY NIGHT...WESTERN PORTIONS OF THE FORECAST AREA SHOULD START
GETTING INTO THE WARM ADVECTION SETUP. UNTIL THEN...MAIN CONCERN IS
FROST/FREEZE SUNDAY NIGHT. MODELS PROG THE SURFACE CANADIAN HIGH
PRESSURE RIDGE TO BE CENTERED OVER THE ENTIRE FORECAST AREA AT 06Z
MONDAY...LEADING TO CLEAR SKIES AND LIGHT WINDS. GIVEN A COOL SUNDAY
TO BEGIN WITH...SITUATION SHOULD BE VERY FAVORABLE FOR FROST/FREEZE
CONDITIONS ACROSS MUCH OF THE FORECAST AREA...ESPECIALLY OVER
WISCONSIN. LEANED TOWARDS THE COOLER SIDE OF GUIDANCE FOR LOWS...
RESULTING IN THE NEED FOR A FREEZE WATCH FOR COUNTIES ALONG AND
NORTHEAST OF I-94. THE WARM ADVECTION MONDAY INTO MONDAY NIGHT IS
INTERESTING AS 850MB TEMPS CLIMB ABOUT 12C FROM 12Z MONDAY TO 12Z
TUESDAY. GOOD MODEL AGREEMENT EXISTS THAT AN AREA OF MID AND HIGH
CLOUDS WILL DEVELOP IN RESPONSE TO THIS WARM ADVECTION. ISENTROPIC
LIFT FIELDS ON THE 295 AND 300K SURFACE SHOW AN AREA OF LIFT
OCCURRING WITHIN THESE CLOUDS...MARCHING EAST WITH TIME. THE 11.00Z
GFS/ECMWF AND 11.03Z SREF ALL DEVELOP PRECIPITATION...WHILE THE
11.00Z NAM IS DRY. THE NAM DOES NOT DEVELOP PRECIPITATION BECAUSE OF
DRY LOW LEVELS ABSORBING THE RAIN...WHICH THE NAM TENDS TO OVERDO.
THUS...HAVE KEPT AND RAISED SLIGHTLY THE PRECIPITATION CHANCES FOR
MONDAY AFTERNOON AND EVENING. DID TAKE OUT THE THUNDER...THOUGH...AS
NO INSTABILITY EXISTS.
FOR THE REST OF THE WEEK...
FOCUS REMAINS ON HIGH TEMPERATURES ON TUESDAY. 11.00Z CANADIAN AND
ECMWF HAVE WENT BACK AND NOW SHOW A SURFACE WARM FRONT PROGRESSING
THROUGH THE AREA QUICKER...WHICH ALLOWS WARMER AIR TO PUSH INTO THE
AREA DURING THE DAY. THE 11.00Z GFS HAS STAYED PERSISTENT. ALL
MODELS NOW SHOW 850MB TEMPS CLIMBING TO 18C OVER CENTRAL WISCONSIN
TO 24C NEAR I-35 BY 00Z...WHICH ARE 2.5 STANDARD DEVIATIONS ABOVE
NORMAL. ONCE YOU GET TO 2.5...CONCERN INCREASES OF REACHING RECORDS.
PROBLEM IS MOST MODEL GUIDANCE HAS TOO MUCH MOISTURE IN THE BOUNDARY
LAYER. THE SCENARIO IS THE GULF OF MEXICO IS CUT OFF BY THE CURRENT
CANADIAN HIGH DROPPING DOWN TO THE GULF COAST...AND CROPS THAT ARE
BEHIND SCHEDULE DUE TO THE COOL SPRING. MODELS ARE TRYING TO GET THE
MOISTURE FROM EVAPOTRANSPORATION. WITH TOO MUCH MOISTURE IN THE
BOUNDARY LAYER...TEMPERATURES CANNOT RISE ENOUGH FROM MIXING.
THUS...HAVE STAYED PRETTY CLOSE TO THE PREVIOUS FORECAST AND BOOSTED
READINGS A FEW DEGREES WEST OF THE MISSISSIPPI RIVER TO ACCOUNT FOR
THE GROWING CONSENSUS ON THE WARM AIR TIMING. TEMPERATURES MAY STILL
NEED TO BE RAISED FURTHER.
A COLD FRONT ACCOMPANYING THAT TROUGH COMING INTO THE PACIFIC
NORTHWEST MONDAY IS SLATED TO COME THROUGH THE FORECAST AREA TUESDAY
NIGHT AND WEDNESDAY. FOLLOWED A CONSENSUS BLEND AND HAVE JUST LOW
CHANCES FOR SHOWERS/STORMS AS THE FRONT MOVES THROUGH. BEYOND
WEDNESDAY...THE FORECAST GETS MUDDLED WITH THE 11.00Z ECMWF/CANADIAN
SUGGESTING MORE OF A ZONAL TO SLIGHT UPPER RIDGING PATTERN IN PLACE
AS TROUGHING REFORMS IN THE PACIFIC NORTHWEST. MEANWHILE...THE
11.00Z GFS/GFS ENSEMBLES DEPICT TROUGHING TO FORM AND LINGER AROUND
THE FORECAST AREA. BOTH SITUATIONS SUGGEST A TREND TOWARDS
DRIER...AND THEREFORE THE CHANCES OF PRECIPITATION HAVE BEEN LOWERED
SOME. COULD SEE FINE TUNING TAKING PLACE TO DRY OUT PORTIONS OF THE
WEDNESDAY NIGHT THROUGH FRIDAY PERIOD. OTHERWISE...TEMPERATURES LOOK
COOLER BUT SHOULD STILL STAY NEAR OR ABOVE NORMAL WITH A MOSTLY
PACIFIC FLOW OF AIR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1100 PM CDT FRI MAY 10 2013
A COLD FRONT WILL SWEEP NORTHWEST TO SOUTHEAST ACROSS THE REGION
EARLY THIS MORNING...LIKELY THROUGH KRST AROUND 08Z AND KLSE
AROUND 10Z. A THIN BAND OF CLOUDS IS CURRENTLY ASSOCIATED WITH THE
FRONT...PER LATEST SATELLITE IMAGERY...WITH SFC OBS PLACING THESE
AROUND 10 KFT. SOME SCT/ISOLD PCPN POST THE FRONT PER 88-D RADAR
IMAGERY...AND MESO MODELS FAVOR BRINGING A SCT-BKN BAND OF -SHRA
ACROSS THE AREA WITH THE PASSAGE OF THE FRONT. THE PCPN THREAT LOOKS
CONFINED TO ABOUT 2 TO 3 HOURS. SFC OBS NOT INDICATING ANY CIGS
LOWER THAN THE MID LEVEL AC...AND MESO MODELS AND BUFKIT SOUNDINGS
ARE NOT TOO EXCITED ABOUT LOW CIGS NOW EITHER. HAVE REMOVED THESE
FROM TAFS AS A RESULT. THE GFS/NAM INDICATE A SWATH OF LOW RH THAT
COULD MANIFEST INTO A FEW HOUR PERIOD OF VFR CIGS LATE MORNING.
ALSO...BUFKIT SOUNDINGS SUGGEST SOME SCT AFTERNOON CU WHICH WOULD
RESULT IN A SHORT PERIOD OF BKN. AGAIN THOUGH...LOOKS TO BE VFR AT
THIS TIME.
WINDS WILL BE ON THE INCREASE POST THE FRONT AS THE SFC PRESSURE
GRADIENT TIGHTENS AND THE WINDS START TO MIX UPWARDS OF 9 KFT. IT
WILL LIKELY BE GUSTY BEFORE 12Z SAT...WITH WINDY/GUSTY CONDITIONS
PERSISTING THROUGH THE DAYLIGHT HOURS. GUSTS AROUND 30 KTS LOOK
REASONABLE FOR KRST...A BIT LESS AT KLSE.
&&
.FIRE WEATHER...
ISSUED AT 343 AM CDT SAT MAY 11 2013
BREEZY NORTHWEST WINDS ARE EXPECTED THIS WEEKEND AHEAD OF A
STRONG AREA OF CANADIAN HIGH PRESSURE OVER SASKATCHEWAN DROPPING
SOUTHEASTWARD. THESE NORTHWEST WINDS ARE GOING TO USHER IN AN
UNSEASONABLY COOL AND DRY AIRMASS INTO THE FORECAST AREA. DEEP
MIXING RESULTING FROM THE STRONG MAY SUN SHOULD ALLOW DEWPOINTS TO
DROP INTO THE MID TEENS TO MID 20S DURING THE AFTERNOON...WHICH
WITH HIGH TEMPERATURES IN THE LOW TO MID 50S...RELATIVE HUMIDITIES
WILL DROP TO 20 TO 30 PERCENT. PRECLUDING A RED FLAG WARNING AT
THIS TIME IS A COMBINATIN OF THE COOL TEMPERATURES...THE RECENT
SOAKING RAIN ON THURSDAY RESULTING IN WETTER FUELS...AND GREEN
UP THAT REALLY TOOK OFF THIS WEEK.
HEADING INTO EARLY NEXT WEEK...FOCUS REMAINS ON TUESDAY AS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA BECOME POSITIONED IN A VERY
WARM ENVIRONMENT. TEMPERATURES LOOK TO CLIMB INTO THE MID TO UPPER
80S...AND PERHAPS COULD EVEN CLIMB INTO THE LOW 90S. DEWPOINT
FORECASTS ARE A LITTLE DIFFICULT AT THIS TIME WITH MOST MODELS
APPEARING TO OVERDO THEM...BUT RELATIVE HUMIDITIES SHOULD DROP AT
LEAST TO 35 TO 40 PERCENT. IT IS POSSIBLE THESE COULD END UP LOWER
AS CERTAINTY ON DEWPOINTS INCREASES. WINDS LOOK MARGINAL RIGHT
NOW FOR RED FLAG CONDITIONS. NEEDLESS TO SAY...SOMETHING TO KEEP
AN EYE ON OVER THE NEXT FEW DAYS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR
WIZ017-029-034-042>044.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....04
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
253 AM MDT SAT MAY 11 2013
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 116 AM MDT SAT MAY 11 2013
FORECAST CHALLENGES DEAL WITH PRECIP CHANCES TODAY...FOLLOWED BY
TEMPERATURES FOR SUNDAY.
CURRENTLY...COLD FRONT HAS MADE IT THROUGH MUCH OF SOUTHEAST
WYOMING EARLY THIS MORNING. WE HAVE NORTH TO NORTHEAST WINDS FOR
JUST ABOUT EVERYWHERE...INCLUDING RAWLINS. 1034MB SURFACE HIGH
OVER ALBERTA CANADA. SEEING A FEW SHOWERS ON RADAR...BUT THEY ARE
QUICKLY MOVING SOUTH INTO NORTHERN COLORADO BEHIND THE FRONT.
FRONT WILL BEGIN TO MOVE BACK TO THE NORTHEAST LATER THIS MORNING
AND SHOULD BE LAYING ALONG THE LARAMIE RANGE DURING PEAK HEATING
THIS AFTERNOON. NAM CAPE VALUES AROUND 400J/KG AND LIFTED INDICES
DOWN TO -2C. ALL THREE MODELS...NAM...GFS AND ECMWF TARGETING THE
SOUTHERN LARAMIE RANGE AS THE BEST CHANCES FOR PRECIP THIS
AFTERNOON AND I RAISED POPS A LITTLE MORE FOR THIS
AREA...INCLUDING CHEYENNE. NORTHERN PANHANDLE...CONVERSE AND
NIOBRARA COUNTIES COULD STAY DRY THROUGH THE DAY.
HEAT UP BEGINS TONIGHT INTO SUNDAY AS 700MB TEMPERATURES RISE IN
RESPONSE TO A BUILDING RIDGE ALOFT. 700MB TEMPERATURES THIS
AFTERNOON OF 0C OVER THE PANHANDLE AND +6C OVER CARBON COUNTY RISE
TO +6C AND +10C RESPECTIVELY BY SUNDAY AFTERNOON. SHOULD SEE
WIDESPREAD 70S ACROSS SOUTHEAST WYOMING AND LOW 80S IN THE
PANHANDLE SUNDAY AFTERNOON.
.LONG TERM...(MONDAY THROUGH FRIDAY NIGHT)
ISSUED AT 226 AM MDT SAT MAY 11 2013
MODELS IN GENERALLY GOOD AGREEMENT THROUGH NEXT WEEK...SHOWING
WARM TEMPERATURES AND DRY CONDITIONS MOST OF THE TIME ACROSS
SOUTHEAST WYOMING AND WESTERN NEBRASKA. UPPER LEVEL RIDGE AXIS
WILL SHIFT FROM UTAH ON SUNDAY INTO THE GREAT PLAINS BY MONDAY
NIGHT. 700MB TEMPERATURES INCREASE BETWEEN 10C TO 13C BY MONDAY
AND TUESDAY...WHICH TRANSLATES TO HIGH TEMPERATURES AT THE SURFACE
IN THE 70S AND 80S...WITH POSSIBLY A FEW LOW 90S ACROSS THE LOWEST
ELEVATIONS OF WESTERN NEBRASKA. A PACIFIC STORM SYSTEM WILL PUSH
EASTWARD ACROSS MONTANA ON TUESDAY...WELL NORTH OF WYOMING. A COLD
FRONT WILL SLOWLY PUSH SOUTH ACROSS THE FORECAST AREA TUESDAY
NIGHT RESULTING IN COOLER TEMPERATURES ON WEDNESDAY...BUT TEMPS
WILL REMAIN NEAR NORMAL FOR THIS TIME OF THE YEAR. BREEZY OR WINDY
CONDITIONS ARE LIKELY ON TUESDAY WITH SOME OF THE WARMEST
TEMPERATURES SO FAR THIS SPRING. TEMPERATURES WILL INCREASE BACK
INTO THE 70S AND LOW 80S BY THE END OF THE WEEK. THE MAIN FORECAST
CHALLENGE IN THE LONG TERM IS PRECIPITATION CHANCES...AS MODELS
INDICATE A SLIGHT CHANCE OF SHOWERS AND TSTORMS EACH DAY FROM
WEDNESDAY THROUGH FRIDAY. THIS WILL DEPEND ON THE POSITION OF A
WEAK COOL FRONT AND MOISTURE GRADIENT WHICH MODELS SHOW ALIGNING
ITSELF ALONG THE LARAMIE RANGE DURING THE DAY...AND RETREATING
EASTWARD ACROSS THE PLAINS AT NIGHT. KEPT A 15 TO 20 PERCENT
CHANCE OF SHOWERS AND TSTORMS ALONG AND EAST OF THE LARAMIE RANGE
EACH DAY. MODEL SOUNDINGS INDICATE ENOUGH CAPE...MOISTURE...AND
INSTABILITY TO SUPPORT ISOLATED COVERAGE OF SHOWERS/TSTORMS
WEDNESDAY AND FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1057 PM MDT FRI MAY 10 2013
COLD FRONT LOOKS TO HAVE MOVED THROUGH THE CHEYENNE AREA WITH
NORTHEASTERLY WINDS IN PLACE NOW. SOME INDICATIONS THAT WE WILL
SEE FOG AT KCYS AND KLAR. HRRR NOT REALLY HITTING THESE TWO
AIRPORTS VERY HARD...SO CONFIDENCE NOT TOO HIGH ON THIS HAPPENING.
IF IT DOES FORM...IT WILL BE RIGHT AROUND SUNRISE AND LAST FOR A
COUPLE HOURS. WILL CONTINUE TO MONITOR.
&&
.FIRE WEATHER...
ISSUED AT 116 AM MDT SAT MAY 11 2013
ONE LAST DAY OF SHOWERS AND THUNDERSTORMS TODAY AS A COLD FRONT
LAYS UP AGAINST THE LARAMIE RANGE. BEST CHANCES FOR WETTING RAINS
WILL BE RIGHT ALONG THE LARAMIE RANGE. CONDITIONS THEN BEGIN TO
WARM AND DRY OUT AS THE FRONT MOVES EAST. MONDAY AND TUESDAY LOOK
TO BE QUITE WARM AND BREEZY...WITH AFTERNOON HUMIDITIES FALLING
INTO THE LOW TO MID TEENS. MOST AREAS ARE IN GREEN UP...BUT FOR
THOSE THAT HAVE NOT...WE COULD BE LOOKING AT RED FLAG CONDITIONS
AS WINDS WILL BE QUITE STRONG. THIS WILL BE ESPECIALLY TRUE FOR
LATE MONDAY AFTERNOON THROUGH TUESDAY. AFTERNOON HUMIDITIES MONDAY
WILL FALL INTO THE LOW TEENS WITH POOR OVERNIGHT RECOVERIES MONDAY
NIGHT.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...CLAYCOMB
LONG TERM...TJT
AVIATION...CLAYCOMB
FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1100 PM MDT FRI MAY 10 2013
.UPDATE...
ISSUED AT 849 PM MDT FRI MAY 10 2013
FORECAST MOSTLY ON TRACK THIS EVENING. A FEW ISOLATED SHOWERS
ACROSS THE AREA AT THIS TIME. A FEW STRONGER GUSTS HAVE BEEN
REPORTED WITH THIS SHOWER ACTIVITY. TORRINGTON AIRPORT REPORTED A
GUST OF 48 MPH AT 805 PM. COULD SEE LOCALIZED GUSTS 40 TO 50 MPH
WITH A FEW SHOWERS YET THIS EVENING BUT WITH THE WITH THE LOSS OF
DAYTIME HEATING...SHOULD SEE GUSTS DECREASING IN STRENGTH. MAY
NEED TO TWEAK TEMPERATURES A BIT FOR THIS EVENING AS TEMPERATURES
ARE DROPPING OFF RATHER QUICKLY UNDER A DRY AIR-MASS. ALSO MAY KNOCK
A FEW DEGREES OFF THE LOWS FOR TONIGHT BUT OTHERWISE EVERYTHING
LOOKING GOOD.
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY AFTERNOON)
ISSUED AT 619 PM MDT FRI MAY 11 2013
COLD FRONT IS MOVING SOUTH THROUGH THE NORTHERN TIER OF COUNTIES AT
TAF ISSUANCE...WITH SCATTERED RAIN SHOWERS MOVING WITH THE
FRONT. THIS ACTIVITY WILL MOVE SOUTH THIS EVENING ACROSS THE
REMAINING AREAS WITH WINDS OUT OF THE NORTH TO NORTHEAST BEHIND
THE FRONT. LOWERING CIGS AND VSBYS ARE EXPECTED AT KLAR AND KCYS
IN MOIST UPSLOPE FLOW LATE TONIGHT. WINDS WILL SHIFT TO THE SOUTH
ACROSS THE EASTERN PLAINS...AND NORTHWEST WEST OF THE LARAMIE
RANGE SATURDAY MORNING. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
INCREASE IN THE AFTERNOON ALONG AND WEST OF THE LARAMIE RANGE WITH
THE FOCUS ALONG THE HIGHER TERRAIN.
&&
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 345 PM MDT FRI MAY 10 2013
A CANADIAN COLD FRONT CONTINUES TO MOVE SOUTH INTO EAST CENTRAL WY
THIS AFTN. AFTN SFC OBS SHOWED THIS FRONT DRAPED FROM WEST TO EAST
FROM NORTHEAST WY INTO WEST CENTRAL SOUTH DAKOTA. LLVL CONVERGENCE
ALONG THIS BOUNDARY...COMBINED WITH DIURNAL INSTABILITY AND MODEST
MIDLVL MOISTURE HAS CONTRIBUTED TO THE DEVELOPMENT OF ISOLATED TO
WIDELY SCATTERED SHOWERS AND TSTMS ACROSS MUCH OF THE AREA. RADAR
HAS NOT INDICATED ANYTHING PARTICULARLY STRONG...AND THIS SHOULD
BE THE CASE THROUGH EARLY EVE WITH SBCAPES GENERALLY LESS THAN
250 J/KG PER SPC MESOSCALE ANALYSIS. MAIN CONVECTIVE HAZARD SHOULD
BE GUSTY DOWNBURST WINDS WITH AN INVERTED-V LOOK TO FCST SOUNDINGS.
THE PREVIOUS FCST LOOKS ON TRACK WITH THE IDEA THAT BETTER PCPN
CHANCES WILL COME DURING THE LATE AFTN AND EARLY EVE. DRY AIR ALOFT
HAS BEEN OVERHEAD FOR MOST OF THE DAY...BUT INCREASING MIDLVL
MOISTURE IN THE POST-FRONTAL AIR MASS SHOULD SUPPORT BETTER PCPN
COVERAGE BY LATE AFTN. STILL LOOKS LIKE ACTIVITY WILL DECREASE AFTER
DARK WITH THE LOSS OF AFTERNOON HEATING AND AS THE FRONT CONTINUES
TO SAG SOUTHWARD INTO NORTHERN CO.
BEST CHANCE FOR CONVECTION THIS PERIOD WILL BE SAT AFTN AND EVE AS
THE SFC BOUNDARY HANGS UP ALONG THE FRONT RANGE. MODELS SHOW STEEP
MIDLVL LAPSE RATES BETWEEN 7 AND 8 DEG C/KM CONTRIBUTING TO A FEW
HUNDRED J/KG OF SBCAPE BY MID AFTN. ENVIRONMENT SHOULD BE PRIME
FOR SHOWER AND THUNDERSTORM ACTIVITY ONCE AGAIN AS LLVL CONVERGENCE
BECOMES ENHANCED ALONG THE LARAMIE RANGE. A DRY BOUNDARY LAYER
WOULD SUGGEST HIGH BASED STORMS WITH GUSTY...SUB-SEVERE WINDS THE
MAIN HAZARD. THERMAL FIELDS REBOUND QUICKLY FOLLOWING THE COLD
FRONTAL PASSAGE AS UPPER-LEVEL RIDGING BUILDS INTO THE AREA. GFS
SHOWS 700 MILLIBAR TEMPS INCREASING TO BETWEEN 3C AND 6C AND 1000-
500 MILLIBAR THICKNESS VALUES AROUND 564 DM. AS SUCH...AFTN HIGHS
SHOULD BE SIMILAR TO FRIDAY WITH MID 60S LIKELY.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 345 PM MDT FRI MAY 10 2013
WARM...DRY...AND INCREASINGLY BREEZY CONDITIONS WILL BE THE
WEATHER STORY FROM SUNDAY INTO EARLY NEXT WEEK. UPPER LEVEL RIDGE
AXIS WILL SHIFT FROM UTAH ON SUNDAY INTO THE PLAINS BY MONDAY
NIGHT. 700MB TEMPS INCREASE TO AROUND 8C BY SUNDAY AND THEN BECOME
11-13C BY MONDAY AND TUESDAY. AS FLOW ALOFT BECOMES MORE
SOUTHWESTERLY AND PRESSURE FALLS OCCUR OVER THE PLAINS ON
MONDAY...THE REGION WILL SEE BREEZY CONDITIONS DEVELOP ESPECIALLY
OVER SOUTHEAST WY. CURRENTLY HAVE WIDESPREAD 80S AND EVEN A FEW 90
DEGREE READINGS IN THE NORTH PLATTE VALLEY EARLY NEXT WEEK.
SHORTWAVE PUSHES ACROSS MONTANA AND THEN INTO THE DAKOTAS ON
TUESDAY NIGHT. THIS WILL PUSH A WEAK COLD FRONT THROUGH THE CWA
DURING THE NIGHT WITH TEMPS ON WEDNESDAY AROUND 10-15 DEGREES
COOLER. LLVL THICKNESSES BEGIN TO RISE AGAIN ON THURSDAY FOR A
RETURN TO ABOVE NORMAL TEMPS. PRECIP CHANCES LOOK QUITE SLIM
THROUGH THE EXTENDED PERIOD WITH A DRY BOUNDARY LAYER AND WARM
MIDLEVEL TEMPS INHIBITING CONVECTION. CAN NOT RULE OUT A FEW HIGH
BASED STORMS EACH AFTN THAT MOSTLY PRODUCE VIRGA AND GUSTY WINDS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 1057 PM MDT FRI MAY 10 2013
COLD FRONT LOOKS TO HAVE MOVED THROUGH THE CHEYENNE AREA WITH
NORTHEASTERLY WINDS IN PLACE NOW. SOME INDICATIONS THAT WE WILL
SEE FOG AT KCYS AND KLAR. HRRR NOT REALLY HITTING THESE TWO
AIRPORTS VERY HARD...SO CONFIDENCE NOT TOO HIGH ON THIS HAPPENING.
IF IT DOES FORM...IT WILL BE RIGHT AROUND SUNRISE AND LAST FOR A
COUPLE HOURS. WILL CONTINUE TO MONITOR.
&&
.FIRE WEATHER...
ISSUED AT 345 PM MDT FRI MAY 10 2013
MOST OF THE AREA IS CURRENTLY GREENING UP DUE TO THE RECENT RAIN
AND SNOW IN THE PAST FEW WEEKS. THE TEMPERATURES WILL BEGIN TO
WARM BY SUNDAY INTO EARLY NEXT WEEK...WITH AN ASSOCIATED DECREASE
IN MINIMUM AFTERNOON HUMIDITIES. MOST OF THE LOWER ELEVATIONS WILL
SEE AFTERNOON HUMIDITIES IN THE 15-20 PERCENT RANGE BY MONDAY AND
TUESDAY. SOUTHWEST-TO-WEST WINDS WILL ALSO INCREASE BY EARLY NEXT
WEEK ESPECIALLY OVER SOUTHEAST WY. WILL HAVE TO MONITOR THE RED
FLAG POTENTIAL EARLY NEXT WEEK OVER THE PANHANDLE SINCE FUELS ARE
CURRENTLY LISTED AS CRITICAL OUT THERE.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...LIEBL
SHORT TERM...HAMMER
LONG TERM...FINCH
AVIATION...CLAYCOMB
FIRE WEATHER...FINCH
AREA FORECAST DISCUSSION
NWS DES MOINES IA
422 AM CDT MON MAY 13 2013
.SHORT TERM.../TODAY /...
ISSUED AT 416 AM CDT MON MAY 13 2013
TEMPS AND SUBTLE PRECIP TRENDS WILL BE THE MAIN CONCERN THIS
MORNING. KINEMATIC FORCING ASSOCIATED WITH CANADIAN SHORT WAVE
STILL WELL REMOVED FROM U.S. BORDER WILL REMAIN TO OUR NORTH AND
EAST TODAY. HOWEVER STRONG THERMODYNAMIC FORCING AHEAD OF THIS
FEATURE AND ADVANCING UPPER LEVEL RIDGE IS CURRENTLY PRODUCING
SCATTERED HIGH BASED SHOWERS ACROSS THE DAKOTAS. MODELS SUGGEST
THIS STRONG THETA-E ADVECTION WILL BRUSH NERN IA AROUND MIDDAY.
THERE IS A DECENT AMOUNT OF DRY AIR BELOW 3KM ON THE MASON CITY
SOUNDING...HOWEVER IT IS SATURATED ABOVE AND UVM ASSOCIATED WITH
STRONG WARM ADVECTION OFTEN IS SUFFICIENT TO GET AT LEAST
SOMETHING TO THE SURFACE. FEEL MODEL QPF AND AREAL COVERAGE OF
MEASURABLE POTENTIAL IS OVERDONE...BUT CONFIDENCE IS THERE TO
INTRODUCE A SHORT PERIOD OF SPRINKLES NE CENTERED AROUND 18Z.
FORECAST SOUNDINGS ADJUSTED FOR RECENT MIXING SUGGEST SOMETHING
CLOSE TO A MOS BLEND FOR HIGHS TODAY...WHICH PERFORMED WELL
YESTERDAY.
.LONG TERM.../TONIGHT THROUGH SUNDAY/...
ISSUED AT 416 AM CDT MON MAY 13 2013
.MAIN FORECAST CONCERN IS WITH HOT TEMPERATURES AND FIRE WEATHER
ON TUESDAY...AND THUNDERSTORM CHANCES LATE IN THE WEEK. LEANED
TOWARD SREF TONIGHT INTO WEDNESDAY AS GFS/NAM/ECMWF ARE TOO COLD
FOR TEMPS TOMORROW.
.TONIGHT THROUGH WEDNESDAY...WAA CONTINUES TONIGHT INTO
TOMORROW AHEAD A COLD FRONT AND AREA OF LOW PRESSURE SET TO MOVE
ACROSS THE FORECAST AREA TUESDAY NIGHT. GOOD MIXING TO 900MB
TOMORROW AND POSSIBLY EVEN HIGHER. THIS MAY TAP INTO THE VERY WARM
850MB TEMPS RANGING FROM 22C TO 25C ACROSS IOWA. WINDS LOOK TO
GUST TO AROUND 25-30 KNOTS ACROSS THE NORTH AND SLIGHTLY LESS
FURTHER SOUTH. VERY DRY AIR MASS MOVING INTO THE STATE FROM THE
PLAINS AND MODELS NOT CAPTURING THE CURRENT DEW POINTS TRENDS OVER
THIS AREA. FELT CURRENT FORECAST AND MODELS WERE TOO HIGH FOR
SURFACE DEW POINTS TONIGHT INTO TOMORROW. PLUS WITH THE GOOD
MIXING...LEANED TOWARD LOWERING DEW POINTS 4 TO 6 DEGREES TONIGHT
INTO TOMORROW WHICH WAS FAIRLY CLOSE TO THE 900MB FROM THE NAM12.
WITH THE DRIER AIR NOW FORECAST...LEANED TOWARD INCREASING MAX
TEMPS FOR TUESDAY ROUGHLY 1-3 DEGREES ACROSS THE FORECAST AREA. IN
SOME PLACES FORECASTING A RECORD HIGH FOR TOMORROW.
COLD FRONT SHOULD ENTER THE NORTHWEST PORTIONS OF THE FORECAST AREA
BY AROUND 00Z WEDNESDAY AND CONTINUE TO TRACK SOUTH OVERNIGHT INTO
WEDNESDAY MORNING. LIMITED MOISTURE WITH FRONT BUT ENOUGH
INSTABILITY AND FORCING TO KEEP MENTION OF SLIGHT CHANCES GOING
TUESDAY INTO WEDNESDAY. FRONT WASHES OUT ACROSS NORTHERN MISSOURI
DURING THE DAY WEDNESDAY AND MAY SEE A STRAY THUNDERSTORM ALONG
THE BORDER.
.THURSDAY THROUGH MONDAY...SURFACE HIGH PRESSURE MOVES BACK IN
OVER THE STATE FOR THURSDAY AND LOOKS TO BE STRONG ENOUGH TO
KEEP CONDITIONS DRY FOR AT LEAST NORTHERN IOWA. ECMWF TRIES TO
BRING MOISTURE NORTHWARD DURING THE DAY AND MAY SEE THUNDERSTORM
ACTIVITY ACROSS THE SOUTH. EXTENDED MODELS IN DECENT AGREEMENT
WITH A SLOW MOVING SURFACE LOW AND UPPER LEVEL TROUGH TO AFFECT
THE PLAINS AND INTO THE CORN BELT FRIDAY INTO THE WEEKEND. BEST
THUNDERSTORM CHANCES IS SATURDAY NIGHT INTO SUNDAY WITH LLJ
DEVELOPING AHEAD OF THE TROUGH.
&&
.AVIATION...13/06Z
ISSUED AT 1113 PM CDT SUN MAY 12 2013
VFR CONDITIONS TO CONTINUE MONDAY INTO TUESDAY MORNING. CLEAR
SKIES WILL CONTINUE UNTIL AROUND 13Z...WHEN WIDESPREAD HIGH AND MID
LEVEL CLOUDS MOVE OVER IOWA FROM THE NORTHWEST. WINDS WILL BE
LIGHT AND VARIABLE THROUGH SUNRISE...AND THEN OUT OF THE SOUTH AT
AROUND 10 TO 15 KNOTS...WITH SOME GUSTS UPWARDS OF 20 TO 25 KNOTS
BY MONDAY AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 416 AM CDT MON MAY 13 2013
FIRE WEATHER CONCERNS ARE INCREASING SOMEWHAT TODAY WITH STRONGER
WIND AND LOW RH DUE TO MIXING. LOCAL AND UPSTREAM SOUNDINGS
INITIALIZED TOO MOIST IN THE LOWEST 1.5KM AT 00Z IN MOST MODELS SO
HAVE DEWPOINTS BELOW MOS AND CONSENSUS. RAP WAS THE DRIEST AND
CLOSEST TO REALITY. DID NOT GO THAT LOW YET BUT LEANED IN THAT
DIRECTION. THIS RESULTED IN MIN RH AROUND 25 PERCENT IN 5-6
COUNTIES W CENTRAL AND NW...BUT SUSTAINED WINDS WILL STAY JUST BELOW
RED FLAG WARNING CRITERIA /25 MPH/. THUS NO HEADLINES TODAY...BUT
WILL MENTION IN HWO AND HIGHLIGHT IN FIRE WEATHER FORECAST. DRYNESS
OF FUELS ALSO SOMEWHAT IN QUESTION OVER NRN IA. USED AS A PROXY FOR
FARTHER WEST WHERE CLIMATE DATA IS MORE QUESTIONABLE...MASON CITY
HAS HAD WETTEST METEOROLOGICAL SPRING TO DATE.
TUESDAY LOOKS TO BE HOTTER AND MUCH DRIER THAN PREVIOUSLY
ANTICIPATED AS MODELS OVERDOING THE SURFACE DEW POINTS ACROSS
CENTRAL IOWA. MIXING UP TO 3000 TO 3500 FEET BY TUESDAY AFTERNOON
WILL RESULT IN DEW POINTS IN THE UPPER 40S TO THE LOWER 50S.
HENCE...RH VALUES ARE FORECAST TO DROP TO 25 PERCENT OR LESS
GENERALLY ALONG AND WEST OF INTERSTATE 35. TEMPS WILL RAPIDLY
INCREASE IN THE MORNING AND THE 25 PERCENT RH VALUES LOOK TO BE
REALIZED BY AROUND NOON. SOUTHWEST WINDS GUSTING TO 30 TO 35 MPH
BY THE AFTERNOON. SO WITH THE LOW RH...GUSTY WINDS...AND HOT
TEMPS...BORDERLINE POTENTIAL FOR A RED FLAG WARNING ACROSS WESTERN
PORTIONS OF THE FORECAST AREA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...SMALL
LONG TERM...PODRAZIK
AVIATION...KOTENBERG
FIRE WEATHER...SMALL/PODRAZIK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
136 AM EDT MON MAY 13 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 404 PM EDT SUN MAY 12 2013
WV IMAGERY AND RUC ANALYSIS INDICATED AN AMPLIFIED PATTERN WITH A
RIDGE OVER WRN NOAM AND A TROUGH OVER THE EAST. THE MID LEVEL LOW
CENTER WAS SLOWLY MOVING OFF TO THE EAST OF CYSB INTO QUEBEC. AT THE
SFC...THE PRES GRADIENT ACROSS LAKE SUPERIOR WAS GRADUALLY WEAKENING
AS THE 998 MB LOW ALSO MOVES INTO QUEBEC AND A RIDGE RIDGE FROM NW
ONTARIO THROUGH WRN MN BUILDS INTO THE UPPER MS VALLEY. RADAR
INDICATED THAT THE LINGERING FLURRIES BTWN MQT-ESC-ISQ WERE
DIMINISHING AS DRIER AIR MOVES IN .
TONIGHT...EXPECT THAT THE REST OF THE LOWER CLOUDS WILL DISSIPATE
DURING THE LATE AFTERNOON AND EARLY EVENING...PER SATELLITE
TRENDS...BUT MAY LINGER A BIT LONGER THAN WHAT SHORT TERM MODEL LOW
LEVEL RH GUIDANCE SUGGESTS. WITH GOOD RADIATIONAL COOLING CONDITIONS
BY LATE THIS EVENING WEST AND OVER NIGHT EAST AND PWAT VALUES BELOW
0.25 INCH...MIN TEMPS SHOULD FALL TOWARD THE LOWER END OF GUIDANCE
AND NEAR RECORD VALUES. THE RECORD FOR THE NWS OFFICE ON 5/12 IS 24
AND ON 5/13 IS 25. READINGS INTO THE UPPER TEENS INTERIOR WEST TO THE
MID 20S EAST ARE EXPECTED WHILE TEMPS AROUND 30 PREVAIL NEAR THE
GREAT LAKES.
MONDAY...AS THE MID/UPPER LEVEL RIDGE OVER THE PLAINS BUILDS TO THE
EAST...A BROAD WAA PATTERN WILL DEVELOP OVER THE UPPER MS VALLEY AND
WRN GREAT LAKES. 295-305K ISENTRPOPIC ASCENT AHEAD OF A TROUGH
MOVING TOWARD MN WILL BRING INCREASING HIGH CLOUDS ACROSS UPPER MI
DURING THE AFTERNOON. THE INITIAL DRY LOW LEVELS AHEAD OF THE BAND
OF MOISTURE/ASCENT WILL LIMIT EASTWARD PROGRESSION OF THE LIGHT PCPN
BAND TO THE FAR WEST DURING THE LATE AFTERNOON WHERE ONLY SLIGHT
CHANCE POPS WERE INCLUDED.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 157 PM EDT SUN MAY 12 2013
SLY FLOW WILL DOMINATE BETWEEN A SFC RIDGE OVER THE ERN CWA AND A
TROUGH OVER THE MN/ND/SD BORDERS AT 00Z TUE. WAA AND ASSOCIATED THIN
BAND OF LIGHT SHOWERS WILL BE OVER THE WRN CWA. COVERAGE OF THESE
RAIN SHOWERS WILL BE LIMITED BY LIMITED MOISTURE...SO WILL KEEP POPS
ON THE LOWER SIDE SIMILAR TO LAST FORECAST. THE PRECIP MOVES TO THE
FAR ERN CWA BY 12Z TUE.
BY 00Z WED...A SHORTWAVE TROUGH AND SFC LOW WILL MOVE TO SRN
MANITOBA...BRINGING A WARM FRONT INTO THE CWA AND A COLD FRONT TO
CENTRAL MN. BY THIS TIME...850MB TEMPS WILL HAVE INCREASED TO AROUND
16C OVER THE WRN CWA AND 9C OVER THE ERN CWA /14C AND 11C WARMER
THAN 24 HOURS BEFORE...RESPECTIVELY/. THE WARM FRONT WILL MOVE
THROUGH THE CWA FOLLOWED SHORTLY AFTER BY THE COLD FRONT WED NIGHT
INTO EARLY WED. WHILE THUNDERSTORMS APPEAR LIKELY GIVEN INSTABILITY
AND STEEP LAPSE RATES...THERE IS SOME UNCERTAINTY WITH CONVECTIVE
STRENGTH. MODEL FORECAST SOUNDINGS INDICATE POTENTIAL FOR OVER
1000J/KG OF ELEVATED CAPE...BUT MODELS SHORT THE DRY SLOT ROTATING
THROUGH AROUND THE SAME TIME AS THE SHORTWAVE...BRINGING AN ELEVATED
MIXED LAYER THAT LEADS TO 100-200J/KG OF CIN. WHETHER THE COLD FRONT
CAN LIFT PARCELS THROUGH THE DRY LAYER AND THE EXACT TIMING OF THE
DRYER AIR REALLY LOWERS CONFIDENCE IN STRONGER THUNDERSTORMS.
ALSO...MODELS NOW AGREE FAIRLY WELL ON TIMING OF THE SYSTEM...BUT
VARY MORE SIGNIFICANTLY ON HOW FAR N OR S TO BRING THE
SYSTEM...WHICH IMPACTS POTENTIAL FORCING FOR ASCENT AND THE STRENGTH
OF THE LOW LEVEL JET. PRECIP DOES APPEAR LIKELY ENOUGH WED NIGHT TO
GO WITH LIKELY POPS /AT LEAST OVER THE NRN AND ERN CWA/...AND
THUNDER ALSO SEEMS LIKE A GOOD BET IN MOST LOCATIONS THAT RECEIVE
RAIN. DEFINITELY NOT SURE ON SEVERE POTENTIAL YET...BUT THERE IS
SOME INDICATION THAT ISOLATED SEVERE WX MAY BE POSSIBLE.
EVEN THOUGH 850MB TEMPS ARE COOLER DURING THE DAY WED THAN
TUE...GOOD MIXING AND SUNSHINE BEHIND THE COLD FRONT WILL LEAD TO
WARMER HIGH TEMPS AND LOWER RH VALUES...COMBINED WITH BREEZY WLY
WINDS. EXPECT HIGHS IN THE 70S INLAND...WITH AROUND 60 EXPECTED
CLOSER TO LAKE SUPERIOR. WILL CONTINUE TREND FROM PREVIOUS SHIFT OF
LOWERING DEW PTS LOWER GIVEN GOOD MIXING AND DRY AIRMASS BEHIND THE
FRONT...LEADING TO MIN RH VALUES IN THE 25-30 PERCENT /OR LOWER/
RANGE OVER INTERIOR CENTRAL AND WEST UPPER MI. INCREASED WINDS ON WED
TO GUSTS TO 30KTS OVER THE WRN CWA /COULD BE HIGHER IF NAM
VERIFIES...BUT IT IS ON THE STRONGER SIDE/. IT IS WORTH NOTING THAT
THE WARMEST TEMPS...LOWEST RH AND HIGHEST WINDS ARE EXPECTED OVER
THE INTERIOR WRN CWA...WHERE THE CHANCES FOR SIGNIFICANT PRECIP TUE
NIGHT ARE THE LOWEST. WILL NEED TO CONTINUE TO MONITOR CONDITIONS
FOR WED...BUT MAY SEE CRITICAL FIRE WEATHER CONDITIONS OVER AT LEAST
PORTIONS OF UPPER MI.
HIGH TEMPS WILL BE A A DEGREE OR TWO COOLER THU...BUT STILL EXPECT
70S INLAND AND AROUND 60 NEAR LAKE SUPERIOR. MIN RH VALUES LOOK TO
BE SIMILAR TO WED ON THE LOW END OF THE COMFORT SCALE FOR FIRE
WX...BUT WINDS WILL BE MUCH LIGHTER AS BROAD HIGH PRESSURE SETTLES
OVER THE REGION.
FOR FRI THROUGH SUN...JUST LOADED A CONSENSUS OF MODEL GUIDANCE DUE
TO INCREASED UNCERTAINTY AND GREATER FOCUS ON FORECAST TUE-THU.
OVERALL...EXPECT TEMPS AROUND SEASONAL NORMALS /A REGULAR SEASONAL
NORMAL...NOT THIS SEASONS NORMAL/ WITH HIGHS IN THE 60S TO LOW 70S.
PRECIP WILL BE POSSIBLE AS FRONTAL ZONES WILL BE NEARBY...BUT
GETTING TOO SPECIFIC AT THIS POINT WOULD BE FUTILE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 135 AM EDT MON MAY 13 2013
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH THE PERIOD.
APPROACH OF NEXT WEATHER DISTURBANCE BY LATE THIS AFTERNOON WILL
BRING A LOW TO MID DECK OF CLOUDS...BUT SHOULD STILL STAY VFR.
THERE WILL BE CHANCES FOR RAIN IN THE EVENING...BUT CHANCE IS STILL
LOW ENOUGH NOT TO PUT INTO TAFS QUITE YET. &&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 404 PM EDT SUN MAY 12 2013
GALES WILL SUBSIDE BY EARLY EVENING AND WINDS OVER THE EAST WILL
DROP BELOW 20 KNOTS OVERNIGHT AS A RIDGE BUILDS INTO THE REGION
WINDS WILL INCREASE OUT OF THE S/SE TO 25 KTS MON NIGHT THROUGH TUE
NIGHT AHEAD OF A LOW PRESSURE SYSTEM MOVING NORTH OF LAKE SUPERIOR
ON WED. A WARM FRONT SLIDING ACROSS LAKE SUPERIOR TUESDAY NIGHT AHEAD
OF THE LOW MAY RESULT IN A FEW STRONGER THUNDERSTORMS. LIGHTNING AND
HEAVY DOWNPOURS WOULD BE THE PRIMARY HAZARDS. EXPECT WINDS TO SHIFT
WESTERLY ON WEDNESDAY BEHIND THE COLD FRONT. POSSIBLE THAT GUSTS
COULD REACH 30 KTS. LIGHTER WINDS ARE EXPECTED AGAIN LATE IN THE WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...TITUS
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
350 AM CDT MON MAY 13 2013
.SYNOPSIS...
ISSUED AT 334 AM CDT MON MAY 13 2013
AT H5 RIDGE OVER THE WESTERN CONUS CLOSED LOW OVER THE GREAT LAKES
WITH TROUGH INTO THE SOUTHEAST CONUS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT MON MAY 13 2013
MODELS IN FAIR AGREEMENT. MAIN CONCERNS WILL BE RECORD HIGHS FOR
WESTERN NEBRASKA TODAY. RECORD AT LBF 91 FOR TODAY. LOT OF CIRRUS
PUSHING OVER THE RIDGE THIS MORNING. MODELS ALWAYS TEND TO UNDER
ESTIMATE THIS. 850MB TEMPERATURES AROUND 25C WHICH WOULD TRANSLATE
TO LOW 90S. RUC COMING UP WITH 95 FOR NORTH PLATTE WHERE MORE
INSOLATION EXPECTED AND WARM FRONT MAKING BIG PUSH. SOME CONVECTION
EXPECTED ON THE EASTERN PLAINS OF WYOMING AND COLORADO LATE THIS
AFTERNOON INTO EARLY EVENING...BUT WILL STRUGGLE TO MOVE INTO THE
NEBRASKA PANHANDLE AND HAVE LEFT THE FORECAST DRY FOR NOW.
TEMPERATURES TO STAY WARM WITH WAA AND SOUTHERLY FLOW TONIGHT
AHEAD OF THE TUESDAY SYSTEM DROPPING ACROSS THE NORTHERN PLAINS.
LOWS EXPECTED IN THE 50S AND 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 334 AM CDT MON MAY 13 2013
A HOT DAY STILL ON TAP FOR TUESDAY...ESPECIALLY ACROSS CENTRAL INTO
SOUTHWEST NEBRASKA. SOME TIMING DIFFERENCES REMAIN WITH THE FRONTAL
PASSAGE. THE 13/00Z NAM CONTINUES TO OFFER THE FASTEST
SOLUTION...AND HAS THE FRONT MOVING INTO CENTRAL AND SOUTHWEST
NEBRASKA BY EARLY AFTERNOON. THE ECMWF AND GFS ARE SLOWER AND BRING
THE FRONT IN TOWARD EVENING. THE NAM COULD BE ONTO SOMETHING...AS IT
MAY BE FASTER AS A RESULT OF A CONVECTIVE COMPLEX ROLLING ACROSS ND
EARLY TUESDAY MORNING. THIS COULD GIVE THE FRONT AN EXTRA PUSH WITH
ANY OUTFLOW FROM THE COMPLEX. A QUICK GLANCE AT THE NEW 13/06Z NAM
SUGGESTS THE FRONT NOW A TAD SLOWER. AT THIS TIME WILL STICK CLOSE
TO THE PREVIOUS FORECAST...WHICH SIDED TOWARD A SLOWER FRONTAL
PASSAGE. WILL CONTINUE THE HOT HIGH TEMPERATURES IN THE MID AND
UPPER 90S ACROSS SOUTHWEST INTO CENTRAL NEBRASKA AHEAD OF THE FRONT.
VERY FAVORABLE CONDITIONS DEVELOP JUST AHEAD OF THE FRONT FOR THE
HOT WEATHER...WITH WEST TO SOUTHWEST SFC WINDS AND DEEP MIXING UP
THROUGH 600 MB. A FIRE WEATHER CONCERN WILL DEVELOP AHEAD OF THE
FRONT AS WELL DUE TO THE DRY CONDITIONS AND DEEP MIXING. MODELS
INDICATE WIND SPEEDS NOT QUITE TO RED FLAG CRITERIA...BUT WINDS MAY
END UP BEING STRONGER THAN THE MODELS INDICATE DUE TO SUCH DEEP
MIXING AHEAD OF THE FRONT. ALSO A CONCERN WOULD BE ANY DRY LIGHTNING
ASSOCIATED WITH THE ISOLATED HIGH BASED STORMS THAT DEVELOP ALONG
THE FRONT AS THE CAP WEAKENS DURING THE MID TO LATE AFTERNOON.
SLIGHT CHANCES FOR STORMS CONTINUE TUESDAY NIGHT AS AN AREA OF
ELEVATED INSTABILITY DEVELOPS TO THE NORTH OF THE COLD FRONT WHICH
WILL BE MOVING SOUTH INTO KS. A WEAK UPPER LEVEL DISTURBANCE WILL
MOVE EAST ACROSS THE AREA AFTER MIDNIGHT AND INTERACT WITH THE
INSTABILITY...SO THE SLIGHT CHANCES FOR PRECIP WILL BE
MAINTAINED.
SOMEWHAT COOLER AND DRIER AIR FILTERS ACROSS THE AREA WEDNESDAY AS
THE COLD FRONT STALLS ACROSS KS.
THUNDERSTORM CHANCES BEGIN TO INCREASE THURSDAY AND THURSDAY NIGHT
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. THE FRONT WHICH STALLED
WEDNESDAY ACROSS KS...WILL BEGIN TO LIFT NORTH AS A WARM FRONT INTO
WESTERN AND NORTH CENTRAL NEBRASKA THURSDAY. AS THIS OCCURS...GULF
MOISTURE WILL SURGE NORTH INTO THE AREA. THE 13/00Z GFS INDICATES
H85 DEW PTS RISING INTO THE 10 TO 12C RANGE DURING THE DAY
THURSDAY...AND INCREASING FURTHER TO 13 TO 15C THURSDAY NIGHT AS THE
LOW LEVEL JET STRENGTHENS. AT THE SAME TIME...SEVERAL SUBTLE UPPER
LEVEL WAVES EJECT NORTHEAST ACROSS THE AREA FROM DEVELOPING WESTERN
CONUS UPPER TROUGH. THIS SET UP WOULD APPEAR FAVORABLE FOR
THUNDERSTORM DEVELOPMENT ACROSS WESTERN NEBRASKA DURING THE LATE
AFTERNOON...BECOMING MORE WIDESPREAD DURING THE EVENING AS THE
SOUTHERLY LOW LEVEL JET INTENSIFIES. THE GFS OFFERS JUST THIS
SCENARIO...WITH THE ECMWF SIMILAR BUT A LITTLE FARTHER EAST WITH THE
BETTER MOISTURE ACROSS CENTRAL NEBRASKA. NAM MODEL NOT QUITE OUT FAR
ENOUGH TO HELP WITH THIS FORECAST PERIOD YET. FOR NOW WILL NOT GET
CARRIED AWAY WITH POPS...WITH THE GFS PROBABLY A TAD ON THE MOIST
SIDE BOTH WITH THE AMOUNT OF MOISTURE AND QPF.
WITH THE UPPER TROUGH REMAINING TO OUR WEST THROUGH SATURDAY
NIGHT...ACTIVE WEATHER WILL CONTINUE. STILL TOO EARLY TO PIN DOWN
EXACTLY WHERE THE BEST FOCUS FOR THUNDERSTORMS WILL BE...BUT
DEVELOPMENT IN OR JUST EAST OF OUR FORECAST AREA SEEMS LIKELY BOTH
FRIDAY AND SATURDAY.
BY SUNDAY BOTH THE 13/00Z RUNS OF THE ECMWF AND GFS DRIVE A COLD
FRONT SOUTHEAST THROUGH THE AREA. THIS WOULD PLACE THE BEST FOCUS
FOR RAIN TO OUR EAST...BUT FOR NOW WILL MAINTAIN THE CHANCES GOING
IN CASE THE FRONT SLOWS SOMEWHAT.
TEMPERATURE WISE...WITH THE INCREASED CLOUD COVER AND MOISTURE...80S
SEEM REASONABLE THURSDAY THROUGH SATURDAY...WITH COOLER UPPER 60S
AND 70S BEHIND THE FRONT SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1124 PM CDT SUN MAY 12 2013
VFR IS EXPECTED OVERNIGHT THROUGH 00Z MONDAY EVENING. THEREAFTER A
COLD FRONT MAY BE SUFFICIENT TO SPARK ISOLATED THUNDERSTORMS ALONG
AND SOUTH OF INTERSTATE 80. ELSEWHERE...VFR SHOULD PREVAIL THROUGH
06Z MONDAY EVENING.
&&
.FIRE WEATHER...
ISSUED AT 334 AM CDT MON MAY 13 2013
WITH TEMPERATURES SOARING TODAY OVER WESTERN NEBRASKA AND DEWPOINTS
IN THE 30S AND 40S MINIMUM RELATIVE HUMIDITIES WILL FALL INTO THE
TEENS ACROSS WESTERN NEBRASKA...BASICALLY WHERE THEY HAVE BEEN THE
LAST SEVERAL DAYS. TUESDAY WILL BE SIMILAR AHEAD OF THE FRONT.
WINDS OVER NORTHERN NEBRASKA WILL BE 10 TO 15 MPH WITH SOME GUSTS
TO THE LOW 20S MAKING IT MARGINAL FOR HIGHLIGHTS. WILL HOLD OFF
FOR NOW. TUESDAY AHEAD OF THE FRONT ACROSS SOUTHWEST INTO CENTRAL
NEBRASKA...HIGHLIGHTS LOOK POSSIBLE...AS WINDS FROM THE SOUTHWEST
INCREASE DUE TO DEEP MIXING...AND DRY LIGHTNING IS POSSIBLE AS
WELL DUE TO THE HIGH BASED NATURE OF ANY STORM THAT WOULD HAPPEN
TO DEVELOP ALONG THE FRONT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...POWER
SHORT TERM...TAYLOR
LONG TERM...POWER
AVIATION...CDC
FIRE WEATHER...POWER
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
352 AM CDT MON MAY 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT MON MAY 13 2013
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
WINDS WILL TAPER DOWN THIS EVENING AND TURN SOUTHERLY OVERNIGHT.
WITH THERMAL PROFILES CONTINUING TO WARM...IT WILL BE A MILD NIGHT
WITH LOWS IN THE MID 50S TO LOWER 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 347 AM CDT MON MAY 13 2013
A STRONG SOUTHERLY FLOW SETS UP ON TUESDAY OUT AHEAD OF A SURFACE
TROUGH/FRONTAL BOUNDARY WHICH WILL PUSH ACROSS THE AREA IN THE
AFTERNOON. MOISTURE LOOKS TO BE MINIMAL WITH THIS SYSTEM...SO
EXPECTING IT TO BE A DRY FRONTAL PASSAGE. IT WILL BE A VERY MIXY DAY
WITH STRONG SOUTHWESTERLY WINDS OUT AHEAD OF THE FRONT...AND STRONG
NORTHWESTERLY WINDS BEHIND THE FRONT. MODELS AGAIN SEEM TO BE
OVERDOING DEWPOINTS ON TUESDAY...MOST LIKELY OVER DOING
EVAPOTRANSPIRATION...AND PROGGING DEWPOINTS WELL INTO THE 50S.
INSTEAD USED THE MIXDOWN TOOL WHICH YIELDED A BETTER ESTIMATION OF
DEWPOINTS...GENERALLY IN THE 40S...WITH SOME MOISTURE POOLING ALONG
THE FRONTAL BOUNDARY...THOUGH STILL MAY BE SLIGHTLY TOO HIGH ON
VALUES. IN ANY EVENT...WITH THE STRONG WINDS AND AFTERNOON RELATIVE
HUMIDITY VALUES FLOATING AROUND 20 TO 25 PERCENT...ISSUED A FIRE
WEATHER WATCH FOR THE ENTIRE CWA. AS HAS BEEN ADVERTISED OF
LATE...TUESDAY WILL GENERALLY BE THE WARMEST DAY OF THE WEEK WITH
ALL MODELS PROGGING 850 MB TEMPERATURES IN THE LOWER TO MID 20S C
OVER OUR EAST IN THE AFTERNOON...SO KEPT WITH LOWER TO MID 90S
THERE. WITH COLD AIR ADVECTION BEHIND THE FRONT...IT WILL BE LITTLE
COOLER TO THE WEST...WITH HIGHS IN THE MID AND UPPER 80S.
COOLER AIR WILL FILTER INTO THE REGION ON TUESDAY NIGHT WITH WINDS
DYING OFF OVERNIGHT. LOWS LOOKING TO BE IN THE UPPER 40S TO MID 50S.
WEDNESDAY AND WEDNESDAY NIGHT APPEAR TO BE PLEASANT WITH WEAK HIGH
PRESSURE BUILDING INTO THE REGION...WITH HIGHS IN THE 70S AND LOWS
IN THE 50S.
FARTHER INTO THE EXTENDED...THURSDAY THROUGH SUNDAY...LOOKS TO BE A
FAIRLY ACTIVE PERIOD WITH A NEARLY ZONAL UPPER LEVEL FLOW AT THE
START OF THE PERIOD...TRANSITIONING TO RIDGING ON FRIDAY AS A TROUGH
BEGINS TO LIFT OUT OF THE WESTERN U.S. AND INTO THE AREA BY LATE IN
THE WEEKEND. THINK MOST OF THURSDAY WILL BE DRY AND LITTLE WARMER AS
A SOUTHERLY FLOW BEGINS TO RETURN TO THE REGION WITH HIGHS IN THE
MID AND UPPER 70S. CANNOT RULE OUT SCATTERED THUNDERSTORMS FOR
THURSDAY NIGHT AND FRIDAY WITH INCREASING THETA E ADVECTION INTO THE
REGION...THOUGH WOULD BE HARD TO PIN POINT EXACT TIMING ON ANY
CONVECTIVE DEVELOPMENT THIS FAR OUT. A BETTER CHANCE OF CONVECTION
WOULD APPEAR TO BE LIKELY ON FRIDAY NIGHT AS LOW PRESSURE BEGINS TO
LIFT OUT OF THE ROCKIES. WITH CONVECTIVE PARAMETERS INCREASING
DURING THAT TIME FRAME...SEVERE STORMS WOULD SEEM MORE
LIKELY...THOUGH MODELS ARE DIFFERING A BIT ON THE PLACEMENT OF A
BOUNDARY LAYING SOMEWHERE CLOSE TO OUR AREA ON FRIDAY NIGHT AND
SATURDAY. THE UPPER LEVEL TROUGH SWINGS THROUGH THE REGION ON
SUNDAY...KEEPING A CHANCE OF CONVECTION...WITH COOLER AIR BEGINNING
TO PULL IN BEHIND THE SYSTEM.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1035 PM CDT SUN MAY 12 2013
VFR CONDITIONS THROUGH THE TAF PERIOD. WINDS WILL BE LIGHT AND
VARIABLE OVERNIGHT THEN INCREASE FROM THE SOUTH LATE TONIGHT THROUGH
MONDAY. AFTER 15Z...WINDS WILL INCREASE AROUND 15 KT WITH GUSTS TO 25
KT AND TURN MORE WESTERLY IN THE AFTERNOON.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR SDZ255>258.
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR MNZ900.
IA...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR IAZ300-301.
NE...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR NEZ249.
&&
$$
SHORT TERM...MJF/JM
LONG TERM...JM
AVIATION...
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1106 PM MDT SUN MAY 12 2013
.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 255 PM MDT SUN MAY 12 2013
MASSIVE WESTERN CONUS UPPER RIDGE CONTINUES TO PUSH
EAST WITH DEEP LAYER THETA-E RIDGING ONGOING. LEE SIDE TROUGH
WILL ADVECT EAST AWAY FROM THE ROCKIES ON THE LEADING EDGE OF
UPPER LEVEL HEIGHT RISES...WITH A STRONG UPPER LEVEL TROUGH
EXPECTED TO ADVANCE INTO THE NORTHERN PLAINS MONDAY
NIGHT...SUPPORTING ANOTHER MORE PRONOUNCED LL TROUGH INTO THE
REGION. OVERALL...MAINLY DRY WEATHER EXPECTED...SAVE FOR PORTIONS
OF THE BLACK HILLS WHERE LL THETA-E ADV COUPLED WITH STEEPENING
MID LEVEL LAPSE RATES AND LOCAL OROGRAPHIC CONVERGENCE MAY SUPPORT
ISOLD SHRA/TS LATE THIS AFTERNOON/EARLY EVENING AND AGAIN MONDAY
AFTERNOON/EVENING. OTHERWISE...A SIG WARM NOSE ASSOCIATED WITH THE
ADVANCING RIDGE IS EXPECTED TO KEEP CONVECTION AT BAY ELSEWHERE.
LATE THIS AFTERNOON/TONIGHT...REMOVED LOW POPS OVER THE
CENTRAL/SOUTHERN BH. NEARLY ALL HIRES MODELS DO NOT GENERATE ANY
CONVECTION...WITH THE NAM BEING THE ONLY MODEL/OUTLIER THAT DOES.
LATEST RAP BUFR PROGS INDICATE MID LEVEL WARMING IS STRONGER/FASTER
THAN PREVIOUS INDICATIONS...WITH A DOWNTREND IN CU NOTED IN SAT
TRENDS. OTHERWISE...A WARM NIGHT EXPECTED WITH LOWS IN THE 50S AT
MANY PLACES. THERE IS A SMALL POTENTIAL FOR AN ELEVATED SHOWER
ACROSS THE FAR NORTH GIVEN THETA-E ADV AT THE BASE OVER THE GROWING
WARM NOSE WITH NEGATIVE SW INDICES. HOWEVER...GIVEN THE LOW
POTENTIAL HAVE LEFT OUT AND WILL LET THE NEXT SHIFT ASSESS.
MONDAY...LEAD LL TROUGH WILL ADVECT EAST ACROSS THE AREA IN THE
MORNING...WITH ONGOING DEEP LAYER WAA. INCREASED LL MOISTURE MAY BE
SUFFICIENT ENOUGH TO GENERATE ISOLD CONVECTION OVER THE BH...ESP
WITH A WEAK MESO LOW AS INDICATED IN THE NAM. RETAINED SLIGHT CHANCE
POPS THERE. OTHERWISE...VERY WARM CONDITIONS EXPECTED WITH LOW TO
MID 90S OVER THE SD PLAINS...COOLER WEST. CURRENT FORECAST TEMPS
SURPASSES THE RECORD OF 92 AT THE RAPID CITY AIRPORT...NEARING THE
DOWNTOWN RECORD OF 94. A VERY WARM NIGHT IS IN STORE FOR MONDAY
NIGHT...WITH LOWS IN THE 60S AT MANY PLACES GIVEN ONGOING SFC
PRESSURE FALLS PER THE ADVANCING DEEP NORTHERN STREAM UPPER IMPULSE.
THIS WILL SUPPORT A MIXED BL WITH GUSTY WINDS POTENTIALLY AT MANY
LOCATIONS...ESP OVER THE NORTHERN BH FOOTHILLS...GIVEN A NEAR 5 MB
SFC PRESSURE DIFFERENTIAL FROM THE BH TO THE PLAINS. RECORD HIGH
MIN/S MAY BE SET AT RAPID CITY.
&&
.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 255 PM MDT SUN MAY 12 2013
UPPER LEVEL RIDGE BREAKS DOWN BY TUESDAY MORNING AS A SURFACE LOW
PASSES TO THE NORTH AND A STRONG COLD FRONT SLIDES QUICKLY ACROSS
THE FORECAST AREA DURING THE MORNING. STRONG NORTHWEST WINDS CAN BE
EXPECTED ACROSS THE NORTHWEST AND WEST CENTRAL SOUTH DAKOTA PLAINS
BEHIND THE FRONT. THE STRONGEST WINDS LOOK TO BE NEAR THE ND BORDER.
HAVE DECIDED TO ISSUE A HIGH WIND WATCH FOR HARDING AND PERKINS
COUNTIES...WHERE SUSTAINED WINDS OF 40 MPH OR MORE LOOK POSSIBLE...
ESPECIALLY DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. HIGH
TEMPERATURES WILL RANGE FROM THE LOWER 70S OVER FAR NORTHWESTERN SD
AND PORTIONS OF NORTHEASTERN WY TO THE UPPER 80S ACROSS SOUTH
CENTRAL SD. DEPENDING ON THE EXACT TIMING OF THE FRONT AND HOW
QUICKLY THE DRIER AIR PUSHES IN BEHIND THE FRONT...THERE IS SOME
POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP ACROSS
PORTIONS OF THE SD PLAINS TUESDAY AFTERNOON. WILL LET LATER SHIFTS
HAVE A LOOK AT UPDATED MODEL DATA FOR THIS POTENTIAL AND WHETHER A
FIRE WX WATCH MAY BE NEEDED.
MORE SEASONABLE TEMPS ARE EXPECTED FOR THE REMAINDER OF THE
WEEK...THOUGH STILL ABOVE AVERAGE...AS AREA REMAINS UNDER ZONAL
FLOW. WEAK DISTURBANCES WITHIN THIS FLOW WILL BRING SOME CHANCES FOR
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS LATE IN THE
WEEK...WITH CHANCES LIKELY INCREASING BY THE WEEKEND. LATEST GFS AND
ECMWF BOTH CONTINUE TO SHOW A STRONGER UPPER TROF IMPACTING THE
REGION FROM LATE FRIDAY THROUGH THE WEEKEND...BRINGING THE POTENTIAL
FOR MORE WIDESPREAD PCPN AND OUR FIRST SEVERE WX OF THE SEASON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1105 PM MDT SUN MAY 12 2013
VFR CONDITIONS ARE EXPECTED THROUGH MONDAY EVENING. OTHERWISE...A
FEW STORMS MAY FORM OVER THE BLKHLS MONDAY AFTN.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON
FOR SDZ001-002.
WY...NONE.
&&
$$
SHORT TERM...JC
LONG TERM...26
AVIATION...BUNKERS
AREA FORECAST DISCUSSION
NWS MIAMI FL
950 AM EDT MON MAY 13 2013
.UPDATE...
NO CHANGES ARE PLANNED FOR THE MORNING UPDATES. THE 12Z MFL
SOUNDING SHOWS THE MID LAYER CAPS ARE MOSTLY GONE BUT THE LAPSE
RATES REMAIN WEAK WITH ONLY MARGINAL INSTABILITY WITH WNW STEERING
FLOW OF AROUND 8-10 KNOTS. THE HRRR DOES NOT GET TOO OVERLY EXCITED AND
AGAIN SHOWS LATE DAY CONVECTION OVER THE INTERIOR AND MOVING
TOWARDS THE EAST COAST METRO REGION AFTER 19Z. THIS SEEMS
REASONABLE GIVEN THE ABOVE DISCUSSION. THE COLD FRONT IS CURRENTLY
JUST NORTH OF LAKE OKEECHOBEE AND QUITE EVIDENT ON VISIBLE
SATELLITE AND HEREIN LIES THE FLY IN THE OINTMENT. THERE IS QUITE
DENSE CLOUD FIELD BEHIND THE FRONT SO IT WILL DEPEND ON HOW QUICK
THIS CLOUD SHIELD MOVES SOUTH AND IF IT HOLDS TOGETHER. IT COULD
CUT OFF SOME OF THE DIURNAL HEATING. BUT FOR NOW WILL LEAVE
FORECAST AS IS BECAUSE THE ATMOSPHERE IS CAPABLE OF PRODUCING SOME
LATE DAY STRONG ACTIVITY IN THE WARM AND HUMID SECTOR SOUTH OF THE
FRONT.
KOB
&&
.PREV DISCUSSION... /ISSUED 720 AM EDT MON MAY 13 2013/
AVIATION...
LIGHT WINDS EARLY THIS MORNING WILL BECOME SOUTHERLY AT 5-10 KNOTS
BY MID-MORNING...THEN INCREASE FURTHER AND VEER SOUTHWESTERLY BY
AFTERNOON IN ADVANCE OF A COLD FRONT. SCATTERED SHOWERS AND
THUNDERSTORMS MAY DEVELOP AHEAD OF THE FRONT...THUS LOCALLY STRONG
WINDS AND BRIEF FLIGHT RESTRICTIONS ARE POSSIBLE. OVERALL...VFR
CONDITIONS WILL PREVAIL TODAY THROUGH MUCH OF THE WEEK. DRIER AIR
FILTERS IN TONIGHT...ENDING SHOWER CHANCES AND CLOUD-COVER. WINDS
OVERNIGHT WILL BE LIGHT AND NORTHWESTERLY.
PREV DISCUSSION... /ISSUED 300 AM EDT MON MAY 13 2013/
.ONE MORE WET DAY BEFORE DRY WEATHER RETURNS TO SOUTH FLORIDA
FOR REST OF THE WEEK...
SHORT TERM...
A COLD FRONT OVER CENTRAL FLORIDA WILL MOVE SOUTH AND THROUGH
SOUTH FLORIDA THIS AFTERNOON INTO EARLY THIS EVENING. THE WINDS
WILL SWING FROM A SOUTHWEST DIRECTION THIS MORNING TO A WESTERLY
DIRECTION THIS AFTERNOON FOCUSING THE SCATTERED SHOWERS AND
THUNDERSTORMS MAINLY OVER THE EASTERN INTERIOR AND EAST COAST
METRO AREAS. SO WILL CONTINUE THE 20 TO 30 PERCENT POPS OVER THE
INTERIOR AREAS AND THE 30 TO 40 PERCENT POPS OVER THE EAST COAST
METRO AREAS FOR THIS AFTERNOON.
A FEW OF THE STORMS COULD EVEN BECOME STRONG LATE THIS AFTERNOON
MAINLY OVER THE EAST COAST METRO AREAS...WHERE THE SEA BREEZES
COLLIDE. THE PRIMARY IMPACTS FROM THE STORMS WILL BE LIGHTNING
STRIKES...GUSTY WINDS...AND LOCALLY HEAVY RAINFALL.
THE COLD FRONT WILL CONTINUE TO MOVE SOUTH INTO THE FLORIDA KEYS
TONIGHT BEFORE STALLING OVER THE CUBA AREA ON TUESDAY. AT THE SAME
TIME...HIGH PRESSURE WILL BUILD INTO THE SOUTHEAST UNITED STATES
FROM THE NORTHWEST. THIS WILL ALLOW FOR A PRESSURE GRADIENT TO
BUILD OVER SOUTH FLORIDA LATE TONIGHT INTO TUESDAY LEADING TO
BREEZY NORTHERLY WINDS OVER SOUTH FLORIDA. THE WEATHER WILL ALSO
BECOME DRY LATE TONIGHT INTO TUESDAY OVER SOUTH FLORIDA...AS DRY
AIR WORKS INTO THE AREA FROM THE NORTH.
THE HIGH WILL THEN SLOWLY MOVE EAST INTO THE WESTERN ATLANTIC
WATERS WEDNESDAY INTO END OF THIS WEEK. THIS WILL ALLOW FOR THE
WINDS TO SWING SLOWLY TO A EASTERLY DIRECTION WHILE SLOWLY
DECREASING TO LESS THEN 10 KNOTS BY END OF THE WEEK. THE DRY
WEATHER WILL REMAIN IN PLACE OVER SOUTH FLORIDA THROUGH END OF
THE WEEK.
LONG TERM...
THE HIGH WILL CONTINUE TO MOVE FURTHER EAST INTO THE ATLANTIC
WATERS THIS WEEKEND INTO EARLY NEXT WEEK. THIS WILL ALLOW FOR THE
WINDS TO BECOME MORE SOUTHEAST BY LATE THIS WEEKEND INTO EARLY NEXT
WEEK...AND ALLOW FOR SOME LOW LEVEL MOISTURE TO RETURN TO THE
AREA. SO HAVE ADDED A SLIGHT CHANCE OF SHOWERS TO THE WESTERN
AREAS OF SOUTH FLORIDA EARLY THIS WEEKEND...BEFORE INCLUDING ALL OF
SOUTH FLORIDA FOR LATE THIS WEEKEND INTO EARLY NEXT WEEK.
MARINE...
THE WESTERLY WINDS TODAY WILL SWING TO A NORTHERLY DIRECTION
TONIGHT INTO TUESDAY...AS SPEEDS INCREASE FROM AROUND 10 KNOTS
TODAY TO 15 TO 20 KNOTS TONIGHT INTO TUESDAY. THE WINDS WILL THEN
SLOWLY SWING TO A EASTERLY DIRECTION WEDNESDAY INTO THURSDAY...AS
SPEEDS SLOWLY DECREASE TO 10 TO 15 KNOTS. THIS WILL ALLOW FOR THE
SEAS IN THE ATLANTIC WATERS TO REMAIN BELOW 6 FEET THROUGH
THURSDAY...EXCEPT 6 FEET IN THE GULF STREAM WATERS TUESDAY
MORNING. ON THE GULF SIDE...THE SEAS WILL BE LESS THAN 6 FEET THIS
THROUGH THURSDAY.
FIRE WEATHER...
THE RELATIVE HUMIDITIES TODAY WILL REMAIN ABOVE THE 35 PERCENT
CRITICAL VALUE OVER SOUTH FLORIDA...DUE TO THE MOISTURE IN PLACE
AHEAD OF THE COLD FRONT. ON TUESDAY...THE RELATIVE HUMIDITIES
SHOULD REMAIN ABOVE THE 35 PERCENT CRITICAL VALUE EXCEPT FOR THE
THE AREA WEST OF LAKE OKEECHOBEE WHERE THEY COULD FALL DOWN TO
AROUND 35 PERCENT FOR COUPLE OF HOURS. THE ERC (ENERGY RELEASE
COMPONENT) ACROSS SOUTH FLORIDA FOR TODAY INTO TUESDAY WILL BE IN
THE 20S. SO NO RED FLAG WATCHES OR WARNING WILL BE NEEDED FOR
SOUTH FLORIDA TODAY INTO TUESDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 87 66 80 67 / 30 10 - -
FORT LAUDERDALE 88 69 81 71 / 40 20 - -
MIAMI 89 70 82 70 / 40 20 - 0
NAPLES 84 66 87 64 / 10 - - 0
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
642 AM CDT MON MAY 13 2013
.SHORT TERM.../TODAY/
ISSUED AT 416 AM CDT MON MAY 13 2013
TEMPS AND SUBTLE PRECIP TRENDS WILL BE THE MAIN CONCERN THIS
MORNING. KINEMATIC FORCING ASSOCIATED WITH CANADIAN SHORT WAVE
STILL WELL REMOVED FROM U.S. BORDER WILL REMAIN TO OUR NORTH AND
EAST TODAY. HOWEVER STRONG THERMODYNAMIC FORCING AHEAD OF THIS
FEATURE AND ADVANCING UPPER LEVEL RIDGE IS CURRENTLY PRODUCING
SCATTERED HIGH BASED SHOWERS ACROSS THE DAKOTAS. MODELS SUGGEST
THIS STRONG THETA-E ADVECTION WILL BRUSH NERN IA AROUND MIDDAY.
THERE IS A DECENT AMOUNT OF DRY AIR BELOW 3KM ON THE MASON CITY
SOUNDING...HOWEVER IT IS SATURATED ABOVE AND UVM ASSOCIATED WITH
STRONG WARM ADVECTION OFTEN IS SUFFICIENT TO GET AT LEAST
SOMETHING TO THE SURFACE. FEEL MODEL QPF AND AREAL COVERAGE OF
MEASURABLE POTENTIAL IS OVERDONE...BUT CONFIDENCE IS THERE TO
INTRODUCE A SHORT PERIOD OF SPRINKLES NE CENTERED AROUND 18Z.
FORECAST SOUNDINGS ADJUSTED FOR RECENT MIXING SUGGEST SOMETHING
CLOSE TO A MOS BLEND FOR HIGHS TODAY...WHICH PERFORMED WELL
YESTERDAY.
.LONG TERM.../TONIGHT THROUGH SUNDAY/
ISSUED AT 416 AM CDT MON MAY 13 2013
MAIN FORECAST CONCERN IS WITH HOT TEMPERATURES AND FIRE WEATHER
ON TUESDAY...AND THUNDERSTORM CHANCES LATE IN THE WEEK. LEANED
TOWARD SREF TONIGHT INTO WEDNESDAY AS GFS/NAM/ECMWF ARE TOO COLD
FOR TEMPS TOMORROW.
TONIGHT THROUGH WEDNESDAY...WAA CONTINUES TONIGHT INTO TOMORROW
AHEAD A COLD FRONT AND AREA OF LOW PRESSURE SET TO MOVE ACROSS THE
FORECAST AREA TUESDAY NIGHT. GOOD MIXING TO 900MB TOMORROW AND
POSSIBLY EVEN HIGHER. THIS MAY TAP INTO THE VERY WARM 850MB TEMPS
RANGING FROM 22C TO 25C ACROSS IOWA. WINDS LOOK TO GUST TO AROUND
25-30 KNOTS ACROSS THE NORTH AND SLIGHTLY LESS FURTHER SOUTH. VERY
DRY AIR MASS MOVING INTO THE STATE FROM THE PLAINS AND MODELS NOT
CAPTURING THE CURRENT DEW POINTS TRENDS OVER THIS AREA. FELT
CURRENT FORECAST AND MODELS WERE TOO HIGH FOR SURFACE DEW POINTS
TONIGHT INTO TOMORROW. PLUS WITH THE GOOD MIXING...LEANED TOWARD
LOWERING DEW POINTS 4 TO 6 DEGREES TONIGHT INTO TOMORROW WHICH WAS
FAIRLY CLOSE TO THE 900MB FROM THE NAM12. WITH THE DRIER AIR NOW
FORECAST...LEANED TOWARD INCREASING MAX TEMPS FOR TUESDAY ROUGHLY
1-3 DEGREES ACROSS THE FORECAST AREA. IN SOME PLACES FORECASTING A
RECORD HIGH FOR TOMORROW.
COLD FRONT SHOULD ENTER THE NORTHWEST PORTIONS OF THE FORECAST AREA
BY AROUND 00Z WEDNESDAY AND CONTINUE TO TRACK SOUTH OVERNIGHT INTO
WEDNESDAY MORNING. LIMITED MOISTURE WITH FRONT BUT ENOUGH
INSTABILITY AND FORCING TO KEEP MENTION OF SLIGHT CHANCES GOING
TUESDAY INTO WEDNESDAY. FRONT WASHES OUT ACROSS NORTHERN MISSOURI
DURING THE DAY WEDNESDAY AND MAY SEE A STRAY THUNDERSTORM ALONG
THE BORDER.
THURSDAY THROUGH MONDAY...SURFACE HIGH PRESSURE MOVES BACK IN
OVER THE STATE FOR THURSDAY AND LOOKS TO BE STRONG ENOUGH TO KEEP
CONDITIONS DRY FOR AT LEAST NORTHERN IOWA. ECMWF TRIES TO BRING
MOISTURE NORTHWARD DURING THE DAY AND MAY SEE THUNDERSTORM
ACTIVITY ACROSS THE SOUTH. EXTENDED MODELS IN DECENT AGREEMENT
WITH A SLOW MOVING SURFACE LOW AND UPPER LEVEL TROUGH TO AFFECT
THE PLAINS AND INTO THE CORN BELT FRIDAY INTO THE WEEKEND. BEST
THUNDERSTORM CHANCES IS SATURDAY NIGHT INTO SUNDAY WITH LLJ
DEVELOPING AHEAD OF THE TROUGH.
&&
.AVIATION...13/12Z
ISSUED AT 641 AM CDT MON MAY 13 2013
VFR CONDITIONS ARE ANTICIPATED THROUGHOUT THE PERIOD. BKN-OVC MID
CLOUDS MAY CROSS IA INTO MIDDAY WITH HIGH BASED SHOWERS
NORTHEAST STRUGGLING TO REACH THE GROUND WITH MUCH AREAL COVERAGE.
TONIGHT SHOULD SEE SOME CLEARING WITH LIGHT SOUTH WINDS...BECOMING
SOUTHWESTERLY.
&&
.FIRE WEATHER...
ISSUED AT 416 AM CDT MON MAY 13 2013
FIRE WEATHER CONCERNS ARE INCREASING SOMEWHAT TODAY WITH STRONGER
WIND AND LOW RH DUE TO MIXING. LOCAL AND UPSTREAM SOUNDINGS
INITIALIZED TOO MOIST IN THE LOWEST 1.5KM AT 00Z IN MOST MODELS SO
HAVE DEWPOINTS BELOW MOS AND CONSENSUS. RAP WAS THE DRIEST AND
CLOSEST TO REALITY. DID NOT GO THAT LOW YET BUT LEANED IN THAT
DIRECTION. THIS RESULTED IN MIN RH AROUND 25 PERCENT IN 5-6
COUNTIES W CENTRAL AND NW...BUT SUSTAINED WINDS WILL STAY JUST BELOW
RED FLAG WARNING CRITERIA /25 MPH/. THUS NO HEADLINES TODAY...BUT
WILL MENTION IN HWO AND HIGHLIGHT IN FIRE WEATHER FORECAST. DRYNESS
OF FUELS ALSO SOMEWHAT IN QUESTION OVER NRN IA. USED AS A PROXY FOR
FARTHER WEST WHERE CLIMATE DATA IS MORE QUESTIONABLE...MASON CITY
HAS HAD WETTEST METEOROLOGICAL SPRING TO DATE.
TUESDAY LOOKS TO BE HOTTER AND MUCH DRIER THAN PREVIOUSLY
ANTICIPATED AS MODELS OVERDOING THE SURFACE DEW POINTS ACROSS
CENTRAL IOWA. MIXING UP TO 3000 TO 3500 FEET BY TUESDAY AFTERNOON
WILL RESULT IN DEW POINTS IN THE UPPER 40S TO THE LOWER 50S.
HENCE...RH VALUES ARE FORECAST TO DROP TO 25 PERCENT OR LESS
GENERALLY ALONG AND WEST OF INTERSTATE 35. TEMPS WILL RAPIDLY
INCREASE IN THE MORNING AND THE 25 PERCENT RH VALUES LOOK TO BE
REALIZED BY AROUND NOON. SOUTHWEST WINDS GUSTING TO 30 TO 35 MPH
BY THE AFTERNOON. SO WITH THE LOW RH...GUSTY WINDS...AND HOT
TEMPS...BORDERLINE POTENTIAL FOR A RED FLAG WARNING ACROSS WESTERN
PORTIONS OF THE FORECAST AREA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...SMALL
LONG TERM...PODRAZIK
AVIATION...SMALL
FIRE WEATHER...SMALL/PODRAZIK
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1041 AM EDT MON MAY 13 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL REMAIN CENTERED OVER THE LOWER
MISSISSIPPI VALLEY TODAY...AS A TROUGH OF LOW PRESSURE PUSHES
THROUGH THE NORTHEAST STATES. THIS PATTERN WILL BRING WELL BELOW
NORMAL TEMPERATURES FOR THE MIDDLE OF MAY. THE HIGH WILL BUILD
INTO THE REGION TONIGHT INTO TUESDAY...AND WILL SLIDE OFF THE
COAST BY TUESDAY NIGHT. MUCH WARMER TEMPERATURES WILL RETURN
WEDNESDAY AND PERSIST INTO THE UPCOMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST SURFACE ANALYSIS SHOWS AN ELONGATED ~1026 MB SURFACE
HIGH SITUATED OVER THE LOWER MS VLY THIS MORNING...WITH A TROUGH
OF LOW PRESSURE DEEPENING OFF THE SC COAST IN RESPONSE TO A STRONG
UPPER TROUGH FROM THE GREAT LAKES SOUTH INTO THE SE CONUS.
MID/HIGH CLOUDS CONTINUE TO OVERSPREAD SE VA/NE NC IN RESPONSE TO
THE LOW OFF THE COAST WHILE MOSTLY SUNNY CONDITIONS PREVAIL
ELSEWHERE...ALTHOUGH THE LATEST VISIBLE IMAGERY INDICATES THE
EARLY STAGES OF CU DEVELOPMENT.
FOR TODAY...A POTENT MID LEVEL SHORTWAVE...CURRENTLY DIVING SOUTH
THROUGH EASTERN OH/WESTERN PA (AND PRODUCING LIGHT SN IN NW PA) WILL
PUSH SSE INTO SOUTH CENTRAL VA AND NE NC BY 00Z THIS EVENING.
WHILE THIS WILL CONTINUE TO DEEPEN THE COASTAL LOW...BULK OF
MOISTURE ASSOCIATED WITH THIS SHOULD STAY OFF THE COAST (PERHAPS
BRINGING A LIGHT SHRA TO THE OUTER BANKS). HOWEVER...DESPITE A
VERY DRY AIRMASS BELOW 800 MB...THE STRONG VORT MAX/PV ANOMALY
DIVES AROUND THE BACK-SIDE OF THE PARENT TROUGH DURING AFTER 18Z
THIS AFTN. THIS IS FORECAST TO DROP 500MB HEIGHTS TO -2 TO -3 ST
DEV BELOW THE MEAN PER 13/00Z GEFS. ADDITIONALLY...LOW AND MID
LEVEL LAPSE RATES WILL BE STEEP WITH COLD AIR ALOFT. GIVEN
THIS...A BKN-OVC SC DECK AROUND 6 K FT IS EXPECTED TO DEVELOP BY
MID AFTERNOON. RADAR WILL PROBABLY SHOW SOME ECHOES ACRS MUCH OF
THE CWA BETWEEN ABOUT 19Z AND 00Z. THE DRY LOW LEVELS (DEW PTS IN
UPPER 20S TO MID 30S) WILL GENLY INHIBIT MUCH OF A CHC FOR
MEASURABLE PRECIP TODAY...BUT GIVEN THE STRONG FORCING AND THE
INCOMING 13/12Z NAM AND HRRR HAVE DECIDED TO CHANGE WEATHER
WORDING FROM PROBABILITY (SLIGHT CHANCE) TO AREAL COVERAGE
(ISOLATED) BUT WILL MAINTAIN A 20 POP. ADDITIONALLY...ISOLATED
POPS HAVE BEEN EXTENDED INTO SE VA/NE NC FOR THE LATE
AFTERNOON/EARLY EVENING BASED ON THE AFOREMENTIONED DATA.
850MB TEMPERATURES DROP TO AROUND -1 C NORTH TO +1 C SOUTH THIS
AFTN...AROUND -2 ST DEV BELOW NORMAL. FULLY MIXED...EXPECT MAX
TEMPS TO RANGE MAINLY FROM THE LOWER TO MID 60S (ABOUT 1.5 TO 2 STD
DEV BELOW SEASONAL MEANS). DAYTIME HIGHS MAY BE REACHED AROUND
MIDDAY BEFORE DROPPING A FEW DEGREES IN THE MID-LATE AFTERNOON AS
CLOUD COVER INCREASES.
NEXT ISSUE WILL BE POTENTIAL RECORD LOWS EARLY TUE MORNING (SEE
CLIMATE SECTION). HAVE ADDED PATCHY FROST TO MUCH OF THE CWA WEST
OF I-95...ALTHOUGH EVEN EAST OF I-95 INTO THE INTERIOR OF SE/E VA
SOME AREAS WILL LIKELY DROP INTO THE UPPER 30S. AT THIS TIME...DE-
COUPLING NOT LIKELY TO OCCUR UNTIL AFTER 06Z...SO DO NOT ANTICIPATE
FROST TO BE WIDESPREAD ENOUGH TO WARRANT A FROST ADSY...ALTHOUGH
IF CLEARING/DE-COUPLING LOOKS TO OCCUR EARLIER...DA SHIFT MAY
CONSIDER ONE FOR PORTIONS OF THE CWA. LOWS IN THE MID TO UPPER 30S
ALONG/WEST OF I-95 AND IN MD...MID 40S IMMEDIATE COAST OF SE VA/NE
NC.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
THE HIGH SLOWLY DRIFTS OVER THE AREA TUESDAY AND THEN OFFSHORE
TUESDAY NIGHT. 850MB TEMPS REMAIN AROUND -2 TO -3 ST DEV BELOW
NORMAL SO HIGHS WILL REMAIN COOL...BUT SHOULD BE SLIGHTLY MILDER
(~ -1.5 ST DEV) DUE TO MORE SOLAR INSOLATION (MAINLY 65-70). HIGH
CLOUDS SHOULD BEGIN TO INCREASE LATER TUESDAY AND ESPECIALLY
TUESDAY NIGHT AS TEMPERATURES ALOFT BEGIN TO INCREASE RAPIDLY AS
RIDGING BUILDS IN FROM THE WEST. MUCH MILDER TUE NIGHT W/ LOWS
PRIMARILY IN THE UPPER 40S TO LWR 50S.
ON WED...SKIES BEGIN PARTLY TO MOSTLY CLOUDY WITH GRADUAL CLEARING
FROM SW TO NE THROUGH THE LATE MORNING AND AFTN. A RATHER DRAMATIC
SHIFT FROM COOL CONDITIONS TUE TO WARMER THAN AVG WX BY WED AFTN AS
850 MB TEMPS WARM BY NEARLY 15 C IN A 24 HR PERIOD. ONLY CAVEAT TO
WARMING TREND COULD BE IF CLOUD COVER DOES NOT BREAK (POSSIBLE
IF A BOUNDARY WERE TO DEVELOP). HIGHS SHOULD RANGE FROM THE UPPER
60S/LWR 70S ALONG THE IMMEDIATE COAST...TO 75-80 IMMEDIATELY
INLAND...TO THE MID 80S ALONG/W OF I-95. WILL NEED TO WATCH
POTENTIAL FOR ISO TSTMS (ESP NORTH) BY LATE AFTN IN WNW FLOW ALOFT
WITH AMPLE CAPE DEVELOPING ACRS THE INTERIOR OF THE CWA (FOR NOW
KEPT FCST MAINLY DRY THRU 00Z/THU).
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A BOUNDARY WILL LIFT THRU THE REGION AND OFFSHR WED NGT THRU THU
MORNG. AT THIS TIME...WILL HAVE CHC TSRA/SHRA MAINLY OVER NE
SECTIONS OF THE CWA DURING THIS PERIOD. WARM AND SOMEWHAT HUMID
CONDITIONS THEN EXPECTED FOR THU THRU SUN...WITH SLGT OR SML CHCS
FOR MAINLY AFTN/EVENG SHOWERS OR TSTMS...AS WEAK BOUNDARIES OR
TROFS DEVELOP AND MOVE ACRS THE AREA IN WNW FLO ALOFT. MIN TEMPS
WILL MAINLY RANGE FM THE UPR 50S TO LWR 60S THRU THE PERIOD. MAX
TEMPS WILL GENERALLY RANGE FM THE UPR 70S TO MID 80S.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR THRU THE TAF PERIOD. MSTLY CLR THIS MRNG AT RIC/SBY WITH
STRATOCU AT ORF/PHF/ECG. THE CLDS SHUD PERSIST THRU THE DAY...AT
6-8K FT. OTW...NORTH WINDS ~10 KT TDY AS SFC HI PRES SLOWLY BLDS
IN FROM THE WEST.
OUTLOOK...VFR AND MAINLY DRY CONDS CONTINUE THIS WEEK WITH LO
DEWPTS MAKING FOG UNLIKELY. THERE WILL BE A CHANCE FOR AFTN
SHWRS/TSTMS THURSDAY AND FRIDAY.
&&
.MARINE...
SCA OVER THE BAY WILL BE ALLOWED TO EXPIRE AT 4 AM AS WINDS
ASSOCIATED WITH A WEAK SURGE ARE NOW STARTING TO FALL TO 10-15 KT.
THESE WINDS WILL CONTINUE THRU THE DAY TDY AS SFC HI PRES SLOWLY
BLDS TOWARDS THE REGION. NWRLY FLOW PERSISTS TNGT WITH THE HI
CENTERED JUST WEST OF THE AREA...AND EXPECT ANOTHER ROUND OF 15-20
KT WINDS OVER THE BAY WITH YET ANOTHER SURGE. SCA TIMING WILL BE
FROM 7 PM TO 7 AM TUE MRNG. EXPECT 15-20 KT OVER COASTAL WATERS AS
WELL WITH 3-4 FT SEAS. HI PRES MOVES DIRECTLY OVER THE AREA TUE AFTN
WITH WINDS AOB 10 KT. SOUTHERLY FLOW RETURNS TUE NGT AND WED AS THE
HI SLIDES OFFSHORE. SEAS WILL APPROACH 5 FT OVER NORTHERN COASTAL
WATERS. ANOTHER FRNT DROPS INTO THE AREA DURING THE SECOND HALF OF
THIS WEEK WITH GENRLY SUB-SCA CONDS EXPECTED.
&&
.CLIMATE...
RECORD LOW TEMPERATURES WILL BE POSSIBLE TUESDAY MORNING (MAY 14TH):
RECORD LOWS FOR MAY 14TH:
RICHMOND....40 (1941)
NORFOLK.....43 (2007)
SALISBURY...32 (2007)
ELIZ CITY...41 (2007)
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 AM EDT
TUESDAY FOR ANZ630>632-634.
&&
$$
SYNOPSIS...LKB
NEAR TERM...LKB/AJZ
SHORT TERM...AJZ/LKB
LONG TERM...TMG
AVIATION...MAS
MARINE...MAS
CLIMATE...AKQ
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
704 AM CDT MON MAY 13 2013
.SYNOPSIS...
ISSUED AT 334 AM CDT MON MAY 13 2013
AT H5 RIDGE OVER THE WESTERN CONUS CLOSED LOW OVER THE GREAT LAKES
WITH TROUGH INTO THE SOUTHEAST CONUS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT MON MAY 13 2013
MODELS IN FAIR AGREEMENT. MAIN CONCERNS WILL BE RECORD HIGHS FOR
WESTERN NEBRASKA TODAY. RECORD AT LBF 91 FOR TODAY. LOT OF CIRRUS
PUSHING OVER THE RIDGE THIS MORNING. MODELS ALWAYS TEND TO UNDER
ESTIMATE THIS. 850MB TEMPERATURES AROUND 25C WHICH WOULD TRANSLATE
TO LOW 90S. RUC COMING UP WITH 95 FOR NORTH PLATTE WHERE MORE
INSOLATION EXPECTED AND WARM FRONT MAKING BIG PUSH. SOME CONVECTION
EXPECTED ON THE EASTERN PLAINS OF WYOMING AND COLORADO LATE THIS
AFTERNOON INTO EARLY EVENING...BUT WILL STRUGGLE TO MOVE INTO THE
NEBRASKA PANHANDLE AND HAVE LEFT THE FORECAST DRY FOR NOW.
TEMPERATURES TO STAY WARM WITH WAA AND SOUTHERLY FLOW TONIGHT
AHEAD OF THE TUESDAY SYSTEM DROPPING ACROSS THE NORTHERN PLAINS.
LOWS EXPECTED IN THE 50S AND 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 334 AM CDT MON MAY 13 2013
A HOT DAY STILL ON TAP FOR TUESDAY...ESPECIALLY ACROSS CENTRAL INTO
SOUTHWEST NEBRASKA. SOME TIMING DIFFERENCES REMAIN WITH THE FRONTAL
PASSAGE. THE 13/00Z NAM CONTINUES TO OFFER THE FASTEST
SOLUTION...AND HAS THE FRONT MOVING INTO CENTRAL AND SOUTHWEST
NEBRASKA BY EARLY AFTERNOON. THE ECMWF AND GFS ARE SLOWER AND BRING
THE FRONT IN TOWARD EVENING. THE NAM COULD BE ONTO SOMETHING...AS IT
MAY BE FASTER AS A RESULT OF A CONVECTIVE COMPLEX ROLLING ACROSS ND
EARLY TUESDAY MORNING. THIS COULD GIVE THE FRONT AN EXTRA PUSH WITH
ANY OUTFLOW FROM THE COMPLEX. A QUICK GLANCE AT THE NEW 13/06Z NAM
SUGGESTS THE FRONT NOW A TAD SLOWER. AT THIS TIME WILL STICK CLOSE
TO THE PREVIOUS FORECAST...WHICH SIDED TOWARD A SLOWER FRONTAL
PASSAGE. WILL CONTINUE THE HOT HIGH TEMPERATURES IN THE MID AND
UPPER 90S ACROSS SOUTHWEST INTO CENTRAL NEBRASKA AHEAD OF THE FRONT.
VERY FAVORABLE CONDITIONS DEVELOP JUST AHEAD OF THE FRONT FOR THE
HOT WEATHER...WITH WEST TO SOUTHWEST SFC WINDS AND DEEP MIXING UP
THROUGH 600 MB. A FIRE WEATHER CONCERN WILL DEVELOP AHEAD OF THE
FRONT AS WELL DUE TO THE DRY CONDITIONS AND DEEP MIXING. MODELS
INDICATE WIND SPEEDS NOT QUITE TO RED FLAG CRITERIA...BUT WINDS MAY
END UP BEING STRONGER THAN THE MODELS INDICATE DUE TO SUCH DEEP
MIXING AHEAD OF THE FRONT. ALSO A CONCERN WOULD BE ANY DRY LIGHTNING
ASSOCIATED WITH THE ISOLATED HIGH BASED STORMS THAT DEVELOP ALONG
THE FRONT AS THE CAP WEAKENS DURING THE MID TO LATE AFTERNOON.
SLIGHT CHANCES FOR STORMS CONTINUE TUESDAY NIGHT AS AN AREA OF
ELEVATED INSTABILITY DEVELOPS TO THE NORTH OF THE COLD FRONT WHICH
WILL BE MOVING SOUTH INTO KS. A WEAK UPPER LEVEL DISTURBANCE WILL
MOVE EAST ACROSS THE AREA AFTER MIDNIGHT AND INTERACT WITH THE
INSTABILITY...SO THE SLIGHT CHANCES FOR PRECIP WILL BE
MAINTAINED.
SOMEWHAT COOLER AND DRIER AIR FILTERS ACROSS THE AREA WEDNESDAY AS
THE COLD FRONT STALLS ACROSS KS.
THUNDERSTORM CHANCES BEGIN TO INCREASE THURSDAY AND THURSDAY NIGHT
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. THE FRONT WHICH STALLED
WEDNESDAY ACROSS KS...WILL BEGIN TO LIFT NORTH AS A WARM FRONT INTO
WESTERN AND NORTH CENTRAL NEBRASKA THURSDAY. AS THIS OCCURS...GULF
MOISTURE WILL SURGE NORTH INTO THE AREA. THE 13/00Z GFS INDICATES
H85 DEW PTS RISING INTO THE 10 TO 12C RANGE DURING THE DAY
THURSDAY...AND INCREASING FURTHER TO 13 TO 15C THURSDAY NIGHT AS THE
LOW LEVEL JET STRENGTHENS. AT THE SAME TIME...SEVERAL SUBTLE UPPER
LEVEL WAVES EJECT NORTHEAST ACROSS THE AREA FROM DEVELOPING WESTERN
CONUS UPPER TROUGH. THIS SET UP WOULD APPEAR FAVORABLE FOR
THUNDERSTORM DEVELOPMENT ACROSS WESTERN NEBRASKA DURING THE LATE
AFTERNOON...BECOMING MORE WIDESPREAD DURING THE EVENING AS THE
SOUTHERLY LOW LEVEL JET INTENSIFIES. THE GFS OFFERS JUST THIS
SCENARIO...WITH THE ECMWF SIMILAR BUT A LITTLE FARTHER EAST WITH THE
BETTER MOISTURE ACROSS CENTRAL NEBRASKA. NAM MODEL NOT QUITE OUT FAR
ENOUGH TO HELP WITH THIS FORECAST PERIOD YET. FOR NOW WILL NOT GET
CARRIED AWAY WITH POPS...WITH THE GFS PROBABLY A TAD ON THE MOIST
SIDE BOTH WITH THE AMOUNT OF MOISTURE AND QPF.
WITH THE UPPER TROUGH REMAINING TO OUR WEST THROUGH SATURDAY
NIGHT...ACTIVE WEATHER WILL CONTINUE. STILL TOO EARLY TO PIN DOWN
EXACTLY WHERE THE BEST FOCUS FOR THUNDERSTORMS WILL BE...BUT
DEVELOPMENT IN OR JUST EAST OF OUR FORECAST AREA SEEMS LIKELY BOTH
FRIDAY AND SATURDAY.
BY SUNDAY BOTH THE 13/00Z RUNS OF THE ECMWF AND GFS DRIVE A COLD
FRONT SOUTHEAST THROUGH THE AREA. THIS WOULD PLACE THE BEST FOCUS
FOR RAIN TO OUR EAST...BUT FOR NOW WILL MAINTAIN THE CHANCES GOING
IN CASE THE FRONT SLOWS SOMEWHAT.
TEMPERATURE WISE...WITH THE INCREASED CLOUD COVER AND MOISTURE...80S
SEEM REASONABLE THURSDAY THROUGH SATURDAY...WITH COOLER UPPER 60S
AND 70S BEHIND THE FRONT SUNDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 700 AM CDT MON MAY 13 2013
VISUAL FLIGHT RULES EXPECTED OVER WESTERN NEBRASKA THROUGH TUESDAY
MORNING. WINDS TODAY WILL BECOME SOUTHWEST AND INCREASE TO 10 TO
15 MPH. HIGH DENSE CIRRUS WILL CONTINUE TO MOVE OVER WESTERN
NEBRASKA THROUGH THE DAY.
&&
.FIRE WEATHER...
ISSUED AT 334 AM CDT MON MAY 13 2013
WITH TEMPERATURES SOARING TODAY OVER WESTERN NEBRASKA AND DEWPOINTS
IN THE 30S AND 40S MINIMUM RELATIVE HUMIDITIES WILL FALL INTO THE
TEENS ACROSS WESTERN NEBRASKA...BASICALLY WHERE THEY HAVE BEEN THE
LAST SEVERAL DAYS. TUESDAY WILL BE SIMILAR AHEAD OF THE FRONT.
WINDS OVER NORTHERN NEBRASKA WILL BE 10 TO 15 MPH WITH SOME GUSTS
TO THE LOW 20S MAKING IT MARGINAL FOR HIGHLIGHTS. WILL HOLD OFF
FOR NOW. TUESDAY AHEAD OF THE FRONT ACROSS SOUTHWEST INTO CENTRAL
NEBRASKA...HIGHLIGHTS LOOK POSSIBLE...AS WINDS FROM THE SOUTHWEST
INCREASE DUE TO DEEP MIXING...AND DRY LIGHTNING IS POSSIBLE AS
WELL DUE TO THE HIGH BASED NATURE OF ANY STORM THAT WOULD HAPPEN
TO DEVELOP ALONG THE FRONT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...POWER
SHORT TERM...TAYLOR
LONG TERM...POWER
AVIATION...POWER
FIRE WEATHER...POWER
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1030 AM CDT MON MAY 13 2013
.UPDATE...
ISSUED AT 1023 AM CDT MON MAY 13 2013
IN GENERAL EARLIER FORECAST IS BEHAVING FAIRLY WELL WITH A LITTLE
SLOWER DECREASE IN THE HIGH CLOUD COVER. STILL EXPECT WITH THE
CLOUDS THINNING OUT BY AFTERNOON THAT THE HEATING AND WARMING WILL
PUT TEMPERATURES CLOSE TO FORECAST HIGHS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT MON MAY 13 2013
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
WINDS WILL TAPER DOWN THIS EVENING AND TURN SOUTHERLY OVERNIGHT.
WITH THERMAL PROFILES CONTINUING TO WARM...IT WILL BE A MILD NIGHT
WITH LOWS IN THE MID 50S TO LOWER 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 347 AM CDT MON MAY 13 2013
A STRONG SOUTHERLY FLOW SETS UP ON TUESDAY OUT AHEAD OF A SURFACE
TROUGH/FRONTAL BOUNDARY WHICH WILL PUSH ACROSS THE AREA IN THE
AFTERNOON. MOISTURE LOOKS TO BE MINIMAL WITH THIS SYSTEM...SO
EXPECTING IT TO BE A DRY FRONTAL PASSAGE. IT WILL BE A VERY MIXY DAY
WITH STRONG SOUTHWESTERLY WINDS OUT AHEAD OF THE FRONT...AND STRONG
NORTHWESTERLY WINDS BEHIND THE FRONT. MODELS AGAIN SEEM TO BE
OVERDOING DEWPOINTS ON TUESDAY...MOST LIKELY OVER DOING
EVAPOTRANSPIRATION...AND PROGGING DEWPOINTS WELL INTO THE 50S.
INSTEAD USED THE MIXDOWN TOOL WHICH YIELDED A BETTER ESTIMATION OF
DEWPOINTS...GENERALLY IN THE 40S...WITH SOME MOISTURE POOLING ALONG
THE FRONTAL BOUNDARY...THOUGH STILL MAY BE SLIGHTLY TOO HIGH ON
VALUES. IN ANY EVENT...WITH THE STRONG WINDS AND AFTERNOON RELATIVE
HUMIDITY VALUES FLOATING AROUND 20 TO 25 PERCENT...ISSUED A FIRE
WEATHER WATCH FOR THE ENTIRE CWA. AS HAS BEEN ADVERTISED OF
LATE...TUESDAY WILL GENERALLY BE THE WARMEST DAY OF THE WEEK WITH
ALL MODELS PROGGING 850 MB TEMPERATURES IN THE LOWER TO MID 20S C
OVER OUR EAST IN THE AFTERNOON...SO KEPT WITH LOWER TO MID 90S
THERE. WITH COLD AIR ADVECTION BEHIND THE FRONT...IT WILL BE LITTLE
COOLER TO THE WEST...WITH HIGHS IN THE MID AND UPPER 80S.
COOLER AIR WILL FILTER INTO THE REGION ON TUESDAY NIGHT WITH WINDS
DYING OFF OVERNIGHT. LOWS LOOKING TO BE IN THE UPPER 40S TO MID 50S.
WEDNESDAY AND WEDNESDAY NIGHT APPEAR TO BE PLEASANT WITH WEAK HIGH
PRESSURE BUILDING INTO THE REGION...WITH HIGHS IN THE 70S AND LOWS
IN THE 50S.
FARTHER INTO THE EXTENDED...THURSDAY THROUGH SUNDAY...LOOKS TO BE A
FAIRLY ACTIVE PERIOD WITH A NEARLY ZONAL UPPER LEVEL FLOW AT THE
START OF THE PERIOD...TRANSITIONING TO RIDGING ON FRIDAY AS A TROUGH
BEGINS TO LIFT OUT OF THE WESTERN U.S. AND INTO THE AREA BY LATE IN
THE WEEKEND. THINK MOST OF THURSDAY WILL BE DRY AND LITTLE WARMER AS
A SOUTHERLY FLOW BEGINS TO RETURN TO THE REGION WITH HIGHS IN THE
MID AND UPPER 70S. CANNOT RULE OUT SCATTERED THUNDERSTORMS FOR
THURSDAY NIGHT AND FRIDAY WITH INCREASING THETA E ADVECTION INTO THE
REGION...THOUGH WOULD BE HARD TO PIN POINT EXACT TIMING ON ANY
CONVECTIVE DEVELOPMENT THIS FAR OUT. A BETTER CHANCE OF CONVECTION
WOULD APPEAR TO BE LIKELY ON FRIDAY NIGHT AS LOW PRESSURE BEGINS TO
LIFT OUT OF THE ROCKIES. WITH CONVECTIVE PARAMETERS INCREASING
DURING THAT TIME FRAME...SEVERE STORMS WOULD SEEM MORE
LIKELY...THOUGH MODELS ARE DIFFERING A BIT ON THE PLACEMENT OF A
BOUNDARY LAYING SOMEWHERE CLOSE TO OUR AREA ON FRIDAY NIGHT AND
SATURDAY. THE UPPER LEVEL TROUGH SWINGS THROUGH THE REGION ON
SUNDAY...KEEPING A CHANCE OF CONVECTION...WITH COOLER AIR BEGINNING
TO PULL IN BEHIND THE SYSTEM.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 649 AM CDT MON MAY 13 2013
CONDITIONS WILL BE VFR TODAY AND TONIGHT. THERE COULD BE SOME
OCCASIONAL GUSTS TO AROUND 30 KNOTS IN NORTHWEST IOWA AND THE
SOUTHERN SECTION OF SOUTHWEST MN FROM ABOUT MIDDAY TO MID
AFTERNOON...WITH DIRECTIONS FROM THE SOUTHWEST. THEN THE WINDS
WILL SUBSIDE. LATE IN THE TAF PERIOD...KHON WAS CLOSE TO NON
CONVECTIVE LOW LEVEL WIND SHEAR. HOWEVER WINDS OFF THE SURFACE ARE
FORECAST TO BE ABOUT 25 TO 30 KNOTS NEAR THE TOP OF THE INVERSION.
SO LEFT OUT FOR NOW.
&&
.FIRE WEATHER...
ISSUED AT 1023 AM CDT MON MAY 13 2013
FIRE WEATHER WAS DISCUSSED EXTENSIVELY IN BOTH SHORT AND LONG TERM
SECTIONS EARLIER. MAIN PROBLEM WITH WINDS COMING UP A LITTLE
FASTER THAN EXPECTED IN OUR EAST IS A POSSIBLE NEED FOR A RED FLAG
WARNING FOR THIS AFTERNOON IN OUR EAST...EVEN THOUGH DEW POINTS
ARE COMING UP ABOUT AS WE HAD. WILL TRY TO ISSUE BY THE START OF
THE AFTERNOON IF WE DECIDE ONE IS NEEDED. OF COURSE WILL ALSO BE
CHECKING ON A POSSIBLE UPGRADE OF TUESDAY WATCH TO A WARNING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR SDZ255>258.
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR MNZ900.
IA...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR IAZ300-301.
NE...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR NEZ249.
&&
$$
UPDATE...
SHORT TERM...MJF/JM
LONG TERM...JM
AVIATION...MJF
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
700 AM CDT MON MAY 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT MON MAY 13 2013
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
WINDS WILL TAPER DOWN THIS EVENING AND TURN SOUTHERLY OVERNIGHT.
WITH THERMAL PROFILES CONTINUING TO WARM...IT WILL BE A MILD NIGHT
WITH LOWS IN THE MID 50S TO LOWER 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 347 AM CDT MON MAY 13 2013
A STRONG SOUTHERLY FLOW SETS UP ON TUESDAY OUT AHEAD OF A SURFACE
TROUGH/FRONTAL BOUNDARY WHICH WILL PUSH ACROSS THE AREA IN THE
AFTERNOON. MOISTURE LOOKS TO BE MINIMAL WITH THIS SYSTEM...SO
EXPECTING IT TO BE A DRY FRONTAL PASSAGE. IT WILL BE A VERY MIXY DAY
WITH STRONG SOUTHWESTERLY WINDS OUT AHEAD OF THE FRONT...AND STRONG
NORTHWESTERLY WINDS BEHIND THE FRONT. MODELS AGAIN SEEM TO BE
OVERDOING DEWPOINTS ON TUESDAY...MOST LIKELY OVER DOING
EVAPOTRANSPIRATION...AND PROGGING DEWPOINTS WELL INTO THE 50S.
INSTEAD USED THE MIXDOWN TOOL WHICH YIELDED A BETTER ESTIMATION OF
DEWPOINTS...GENERALLY IN THE 40S...WITH SOME MOISTURE POOLING ALONG
THE FRONTAL BOUNDARY...THOUGH STILL MAY BE SLIGHTLY TOO HIGH ON
VALUES. IN ANY EVENT...WITH THE STRONG WINDS AND AFTERNOON RELATIVE
HUMIDITY VALUES FLOATING AROUND 20 TO 25 PERCENT...ISSUED A FIRE
WEATHER WATCH FOR THE ENTIRE CWA. AS HAS BEEN ADVERTISED OF
LATE...TUESDAY WILL GENERALLY BE THE WARMEST DAY OF THE WEEK WITH
ALL MODELS PROGGING 850 MB TEMPERATURES IN THE LOWER TO MID 20S C
OVER OUR EAST IN THE AFTERNOON...SO KEPT WITH LOWER TO MID 90S
THERE. WITH COLD AIR ADVECTION BEHIND THE FRONT...IT WILL BE LITTLE
COOLER TO THE WEST...WITH HIGHS IN THE MID AND UPPER 80S.
COOLER AIR WILL FILTER INTO THE REGION ON TUESDAY NIGHT WITH WINDS
DYING OFF OVERNIGHT. LOWS LOOKING TO BE IN THE UPPER 40S TO MID 50S.
WEDNESDAY AND WEDNESDAY NIGHT APPEAR TO BE PLEASANT WITH WEAK HIGH
PRESSURE BUILDING INTO THE REGION...WITH HIGHS IN THE 70S AND LOWS
IN THE 50S.
FARTHER INTO THE EXTENDED...THURSDAY THROUGH SUNDAY...LOOKS TO BE A
FAIRLY ACTIVE PERIOD WITH A NEARLY ZONAL UPPER LEVEL FLOW AT THE
START OF THE PERIOD...TRANSITIONING TO RIDGING ON FRIDAY AS A TROUGH
BEGINS TO LIFT OUT OF THE WESTERN U.S. AND INTO THE AREA BY LATE IN
THE WEEKEND. THINK MOST OF THURSDAY WILL BE DRY AND LITTLE WARMER AS
A SOUTHERLY FLOW BEGINS TO RETURN TO THE REGION WITH HIGHS IN THE
MID AND UPPER 70S. CANNOT RULE OUT SCATTERED THUNDERSTORMS FOR
THURSDAY NIGHT AND FRIDAY WITH INCREASING THETA E ADVECTION INTO THE
REGION...THOUGH WOULD BE HARD TO PIN POINT EXACT TIMING ON ANY
CONVECTIVE DEVELOPMENT THIS FAR OUT. A BETTER CHANCE OF CONVECTION
WOULD APPEAR TO BE LIKELY ON FRIDAY NIGHT AS LOW PRESSURE BEGINS TO
LIFT OUT OF THE ROCKIES. WITH CONVECTIVE PARAMETERS INCREASING
DURING THAT TIME FRAME...SEVERE STORMS WOULD SEEM MORE
LIKELY...THOUGH MODELS ARE DIFFERING A BIT ON THE PLACEMENT OF A
BOUNDARY LAYING SOMEWHERE CLOSE TO OUR AREA ON FRIDAY NIGHT AND
SATURDAY. THE UPPER LEVEL TROUGH SWINGS THROUGH THE REGION ON
SUNDAY...KEEPING A CHANCE OF CONVECTION...WITH COOLER AIR BEGINNING
TO PULL IN BEHIND THE SYSTEM.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 649 AM CDT MON MAY 13 2013
CONDITIONS WILL BE VFR TODAY AND TONIGHT. THERE COULD BE SOME
OCCASIONAL GUSTS TO AROUND 30 KNOTS IN NORTHWEST IOWA AND THE
SOUTHERN SECTION OF SOUTHWEST MN FROM ABOUT MIDDAY TO MID
AFTERNOON...WITH DIRECTIONS FROM THE SOUTHWEST. THEN THE WINDS
WILL SUBSIDE. LATE IN THE TAF PERIOD...KHON WAS CLOSE TO NON
CONVECTIVE LOW LEVEL WIND SHEAR. HOWEVER WINDS OFF THE SURFACE ARE
FORECAST TO BE ABOUT 25 TO 30 KNOTS NEAR THE TOP OF THE INVERSION.
SO LEFT OUT FOR NOW.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR SDZ255>258.
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR MNZ900.
IA...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR IAZ300-301.
NE...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR NEZ249.
&&
$$
SHORT TERM...MJF/JM
LONG TERM...JM
AVIATION...MJF
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1227 PM CDT MON MAY 13 2013
.UPDATE...
ISSUED AT 1201 PM CDT MON MAY 13 2013
WARM AIR ADVECTION LIGHT SHOWERS CONTINUE TO DEVELOP ACROSS
NORTHERN IOWA AND SOUTHERN MN HEADING SOUTHEAST WITH H700 FLOW.
HAVE UPDATED ZONES TO INCLUDE A FEW SPRINKLES OVER THE NORTHERN
SECTIONS FOR THE NEXT HOUR OR TWO.
&&
.SHORT TERM.../TODAY/
ISSUED AT 416 AM CDT MON MAY 13 2013
TEMPS AND SUBTLE PRECIP TRENDS WILL BE THE MAIN CONCERN THIS
MORNING. KINEMATIC FORCING ASSOCIATED WITH CANADIAN SHORT WAVE
STILL WELL REMOVED FROM U.S. BORDER WILL REMAIN TO OUR NORTH AND
EAST TODAY. HOWEVER STRONG THERMODYNAMIC FORCING AHEAD OF THIS
FEATURE AND ADVANCING UPPER LEVEL RIDGE IS CURRENTLY PRODUCING
SCATTERED HIGH BASED SHOWERS ACROSS THE DAKOTAS. MODELS SUGGEST
THIS STRONG THETA-E ADVECTION WILL BRUSH NERN IA AROUND MIDDAY.
THERE IS A DECENT AMOUNT OF DRY AIR BELOW 3KM ON THE MASON CITY
SOUNDING...HOWEVER IT IS SATURATED ABOVE AND UVM ASSOCIATED WITH
STRONG WARM ADVECTION OFTEN IS SUFFICIENT TO GET AT LEAST
SOMETHING TO THE SURFACE. FEEL MODEL QPF AND AREAL COVERAGE OF
MEASURABLE POTENTIAL IS OVERDONE...BUT CONFIDENCE IS THERE TO
INTRODUCE A SHORT PERIOD OF SPRINKLES NE CENTERED AROUND 18Z.
FORECAST SOUNDINGS ADJUSTED FOR RECENT MIXING SUGGEST SOMETHING
CLOSE TO A MOS BLEND FOR HIGHS TODAY...WHICH PERFORMED WELL
YESTERDAY.
.LONG TERM.../TONIGHT THROUGH SUNDAY/
ISSUED AT 416 AM CDT MON MAY 13 2013
MAIN FORECAST CONCERN IS WITH HOT TEMPERATURES AND FIRE WEATHER
ON TUESDAY...AND THUNDERSTORM CHANCES LATE IN THE WEEK. LEANED
TOWARD SREF TONIGHT INTO WEDNESDAY AS GFS/NAM/ECMWF ARE TOO COLD
FOR TEMPS TOMORROW.
TONIGHT THROUGH WEDNESDAY...WAA CONTINUES TONIGHT INTO TOMORROW
AHEAD A COLD FRONT AND AREA OF LOW PRESSURE SET TO MOVE ACROSS THE
FORECAST AREA TUESDAY NIGHT. GOOD MIXING TO 900MB TOMORROW AND
POSSIBLY EVEN HIGHER. THIS MAY TAP INTO THE VERY WARM 850MB TEMPS
RANGING FROM 22C TO 25C ACROSS IOWA. WINDS LOOK TO GUST TO AROUND
25-30 KNOTS ACROSS THE NORTH AND SLIGHTLY LESS FURTHER SOUTH. VERY
DRY AIR MASS MOVING INTO THE STATE FROM THE PLAINS AND MODELS NOT
CAPTURING THE CURRENT DEW POINTS TRENDS OVER THIS AREA. FELT
CURRENT FORECAST AND MODELS WERE TOO HIGH FOR SURFACE DEW POINTS
TONIGHT INTO TOMORROW. PLUS WITH THE GOOD MIXING...LEANED TOWARD
LOWERING DEW POINTS 4 TO 6 DEGREES TONIGHT INTO TOMORROW WHICH WAS
FAIRLY CLOSE TO THE 900MB FROM THE NAM12. WITH THE DRIER AIR NOW
FORECAST...LEANED TOWARD INCREASING MAX TEMPS FOR TUESDAY ROUGHLY
1-3 DEGREES ACROSS THE FORECAST AREA. IN SOME PLACES FORECASTING A
RECORD HIGH FOR TOMORROW.
COLD FRONT SHOULD ENTER THE NORTHWEST PORTIONS OF THE FORECAST AREA
BY AROUND 00Z WEDNESDAY AND CONTINUE TO TRACK SOUTH OVERNIGHT INTO
WEDNESDAY MORNING. LIMITED MOISTURE WITH FRONT BUT ENOUGH
INSTABILITY AND FORCING TO KEEP MENTION OF SLIGHT CHANCES GOING
TUESDAY INTO WEDNESDAY. FRONT WASHES OUT ACROSS NORTHERN MISSOURI
DURING THE DAY WEDNESDAY AND MAY SEE A STRAY THUNDERSTORM ALONG
THE BORDER.
THURSDAY THROUGH MONDAY...SURFACE HIGH PRESSURE MOVES BACK IN
OVER THE STATE FOR THURSDAY AND LOOKS TO BE STRONG ENOUGH TO KEEP
CONDITIONS DRY FOR AT LEAST NORTHERN IOWA. ECMWF TRIES TO BRING
MOISTURE NORTHWARD DURING THE DAY AND MAY SEE THUNDERSTORM
ACTIVITY ACROSS THE SOUTH. EXTENDED MODELS IN DECENT AGREEMENT
WITH A SLOW MOVING SURFACE LOW AND UPPER LEVEL TROUGH TO AFFECT
THE PLAINS AND INTO THE CORN BELT FRIDAY INTO THE WEEKEND. BEST
THUNDERSTORM CHANCES IS SATURDAY NIGHT INTO SUNDAY WITH LLJ
DEVELOPING AHEAD OF THE TROUGH.
&&
.AVIATION...13/18Z
ISSUED AT 1226 PM CDT MON MAY 13 2013
MAIN CONCERNS THIS PERIOD AND JUST BEYOND WILL BE WINDS. SOME MID
TO HIGH LEVEL BKN CLOUDS ACROSS THE FORECAST AREA WILL MOVE ESE
THIS AFTERNOON. OTHER THAN A FEW SPRINKLES...NO ORGANIZED
CONVECTION EXPECTED WITH THIS PUSH OF WARM AIR. HOWEVER...WINDS
HAVE BEEN GUSTING NORTHWEST SITES AS MIXED LAYER INCREASES IN
DEPTH. EXPECT MOST SITES TO SEE GUSTS TO 20 TO 25 KTS THROUGH 01Z
WHEN DECOUPLING OCCURS. PUSH OF WARMER AIR TO ARRIVE TUESDAY AND
DEPTH OF MIXED LAYER INCREASES AGAIN AFT 18Z. MAY SEE SUSTAINED SFC
WINDS 20 TO 25 KTS WITH GUSTS 35 TO 40KTS...MAINLY NORTH SITES...AFT 19Z
TUESDAY AS MIXING MAXIMIZED DURING THE AFTERNOON HOURS.
&&
.FIRE WEATHER...
ISSUED AT 416 AM CDT MON MAY 13 2013
FIRE WEATHER CONCERNS ARE INCREASING SOMEWHAT TODAY WITH STRONGER
WIND AND LOW RH DUE TO MIXING. LOCAL AND UPSTREAM SOUNDINGS
INITIALIZED TOO MOIST IN THE LOWEST 1.5KM AT 00Z IN MOST MODELS SO
HAVE DEWPOINTS BELOW MOS AND CONSENSUS. RAP WAS THE DRIEST AND
CLOSEST TO REALITY. DID NOT GO THAT LOW YET BUT LEANED IN THAT
DIRECTION. THIS RESULTED IN MIN RH AROUND 25 PERCENT IN 5-6
COUNTIES W CENTRAL AND NW...BUT SUSTAINED WINDS WILL STAY JUST BELOW
RED FLAG WARNING CRITERIA /25 MPH/. THUS NO HEADLINES TODAY...BUT
WILL MENTION IN HWO AND HIGHLIGHT IN FIRE WEATHER FORECAST. DRYNESS
OF FUELS ALSO SOMEWHAT IN QUESTION OVER NRN IA. USED AS A PROXY FOR
FARTHER WEST WHERE CLIMATE DATA IS MORE QUESTIONABLE...MASON CITY
HAS HAD WETTEST METEOROLOGICAL SPRING TO DATE.
TUESDAY LOOKS TO BE HOTTER AND MUCH DRIER THAN PREVIOUSLY
ANTICIPATED AS MODELS OVERDOING THE SURFACE DEW POINTS ACROSS
CENTRAL IOWA. MIXING UP TO 3000 TO 3500 FEET BY TUESDAY AFTERNOON
WILL RESULT IN DEW POINTS IN THE UPPER 40S TO THE LOWER 50S.
HENCE...RH VALUES ARE FORECAST TO DROP TO 25 PERCENT OR LESS
GENERALLY ALONG AND WEST OF INTERSTATE 35. TEMPS WILL RAPIDLY
INCREASE IN THE MORNING AND THE 25 PERCENT RH VALUES LOOK TO BE
REALIZED BY AROUND NOON. SOUTHWEST WINDS GUSTING TO 30 TO 35 MPH
BY THE AFTERNOON. SO WITH THE LOW RH...GUSTY WINDS...AND HOT
TEMPS...BORDERLINE POTENTIAL FOR A RED FLAG WARNING ACROSS WESTERN
PORTIONS OF THE FORECAST AREA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...REV
SHORT TERM...SMALL
LONG TERM...PODRAZIK
AVIATION...REV
FIRE WEATHER...SMALL/PODRAZIK
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
1203 PM CDT MON MAY 13 2013
.UPDATE...
ISSUED AT 1201 PM CDT MON MAY 13 2013
WARM AIR ADVECTION LIGHT SHOWERS CONTINUE TO DEVELOP ACROSS
NORTHERN IOWA AND SOUTHERN MN HEADING SOUTHEAST WITH H700 FLOW.
HAVE UPDATED ZONES TO INCLUDE A FEW SPRINKLES OVER THE NORTHERN
SECTIONS FOR THE NEXT HOUR OR TWO.
&&
.SHORT TERM.../TODAY/
ISSUED AT 416 AM CDT MON MAY 13 2013
TEMPS AND SUBTLE PRECIP TRENDS WILL BE THE MAIN CONCERN THIS
MORNING. KINEMATIC FORCING ASSOCIATED WITH CANADIAN SHORT WAVE
STILL WELL REMOVED FROM U.S. BORDER WILL REMAIN TO OUR NORTH AND
EAST TODAY. HOWEVER STRONG THERMODYNAMIC FORCING AHEAD OF THIS
FEATURE AND ADVANCING UPPER LEVEL RIDGE IS CURRENTLY PRODUCING
SCATTERED HIGH BASED SHOWERS ACROSS THE DAKOTAS. MODELS SUGGEST
THIS STRONG THETA-E ADVECTION WILL BRUSH NERN IA AROUND MIDDAY.
THERE IS A DECENT AMOUNT OF DRY AIR BELOW 3KM ON THE MASON CITY
SOUNDING...HOWEVER IT IS SATURATED ABOVE AND UVM ASSOCIATED WITH
STRONG WARM ADVECTION OFTEN IS SUFFICIENT TO GET AT LEAST
SOMETHING TO THE SURFACE. FEEL MODEL QPF AND AREAL COVERAGE OF
MEASURABLE POTENTIAL IS OVERDONE...BUT CONFIDENCE IS THERE TO
INTRODUCE A SHORT PERIOD OF SPRINKLES NE CENTERED AROUND 18Z.
FORECAST SOUNDINGS ADJUSTED FOR RECENT MIXING SUGGEST SOMETHING
CLOSE TO A MOS BLEND FOR HIGHS TODAY...WHICH PERFORMED WELL
YESTERDAY.
.LONG TERM.../TONIGHT THROUGH SUNDAY/
ISSUED AT 416 AM CDT MON MAY 13 2013
MAIN FORECAST CONCERN IS WITH HOT TEMPERATURES AND FIRE WEATHER
ON TUESDAY...AND THUNDERSTORM CHANCES LATE IN THE WEEK. LEANED
TOWARD SREF TONIGHT INTO WEDNESDAY AS GFS/NAM/ECMWF ARE TOO COLD
FOR TEMPS TOMORROW.
TONIGHT THROUGH WEDNESDAY...WAA CONTINUES TONIGHT INTO TOMORROW
AHEAD A COLD FRONT AND AREA OF LOW PRESSURE SET TO MOVE ACROSS THE
FORECAST AREA TUESDAY NIGHT. GOOD MIXING TO 900MB TOMORROW AND
POSSIBLY EVEN HIGHER. THIS MAY TAP INTO THE VERY WARM 850MB TEMPS
RANGING FROM 22C TO 25C ACROSS IOWA. WINDS LOOK TO GUST TO AROUND
25-30 KNOTS ACROSS THE NORTH AND SLIGHTLY LESS FURTHER SOUTH. VERY
DRY AIR MASS MOVING INTO THE STATE FROM THE PLAINS AND MODELS NOT
CAPTURING THE CURRENT DEW POINTS TRENDS OVER THIS AREA. FELT
CURRENT FORECAST AND MODELS WERE TOO HIGH FOR SURFACE DEW POINTS
TONIGHT INTO TOMORROW. PLUS WITH THE GOOD MIXING...LEANED TOWARD
LOWERING DEW POINTS 4 TO 6 DEGREES TONIGHT INTO TOMORROW WHICH WAS
FAIRLY CLOSE TO THE 900MB FROM THE NAM12. WITH THE DRIER AIR NOW
FORECAST...LEANED TOWARD INCREASING MAX TEMPS FOR TUESDAY ROUGHLY
1-3 DEGREES ACROSS THE FORECAST AREA. IN SOME PLACES FORECASTING A
RECORD HIGH FOR TOMORROW.
COLD FRONT SHOULD ENTER THE NORTHWEST PORTIONS OF THE FORECAST AREA
BY AROUND 00Z WEDNESDAY AND CONTINUE TO TRACK SOUTH OVERNIGHT INTO
WEDNESDAY MORNING. LIMITED MOISTURE WITH FRONT BUT ENOUGH
INSTABILITY AND FORCING TO KEEP MENTION OF SLIGHT CHANCES GOING
TUESDAY INTO WEDNESDAY. FRONT WASHES OUT ACROSS NORTHERN MISSOURI
DURING THE DAY WEDNESDAY AND MAY SEE A STRAY THUNDERSTORM ALONG
THE BORDER.
THURSDAY THROUGH MONDAY...SURFACE HIGH PRESSURE MOVES BACK IN
OVER THE STATE FOR THURSDAY AND LOOKS TO BE STRONG ENOUGH TO KEEP
CONDITIONS DRY FOR AT LEAST NORTHERN IOWA. ECMWF TRIES TO BRING
MOISTURE NORTHWARD DURING THE DAY AND MAY SEE THUNDERSTORM
ACTIVITY ACROSS THE SOUTH. EXTENDED MODELS IN DECENT AGREEMENT
WITH A SLOW MOVING SURFACE LOW AND UPPER LEVEL TROUGH TO AFFECT
THE PLAINS AND INTO THE CORN BELT FRIDAY INTO THE WEEKEND. BEST
THUNDERSTORM CHANCES IS SATURDAY NIGHT INTO SUNDAY WITH LLJ
DEVELOPING AHEAD OF THE TROUGH.
&&
.AVIATION...13/12Z
ISSUED AT 641 AM CDT MON MAY 13 2013
VFR CONDITIONS ARE ANTICIPATED THROUGHOUT THE PERIOD. BKN-OVC MID
CLOUDS MAY CROSS IA INTO MIDDAY WITH HIGH BASED SHOWERS
NORTHEAST STRUGGLING TO REACH THE GROUND WITH MUCH AREAL COVERAGE.
TONIGHT SHOULD SEE SOME CLEARING WITH LIGHT SOUTH WINDS...BECOMING
SOUTHWESTERLY.
&&
.FIRE WEATHER...
ISSUED AT 416 AM CDT MON MAY 13 2013
FIRE WEATHER CONCERNS ARE INCREASING SOMEWHAT TODAY WITH STRONGER
WIND AND LOW RH DUE TO MIXING. LOCAL AND UPSTREAM SOUNDINGS
INITIALIZED TOO MOIST IN THE LOWEST 1.5KM AT 00Z IN MOST MODELS SO
HAVE DEWPOINTS BELOW MOS AND CONSENSUS. RAP WAS THE DRIEST AND
CLOSEST TO REALITY. DID NOT GO THAT LOW YET BUT LEANED IN THAT
DIRECTION. THIS RESULTED IN MIN RH AROUND 25 PERCENT IN 5-6
COUNTIES W CENTRAL AND NW...BUT SUSTAINED WINDS WILL STAY JUST BELOW
RED FLAG WARNING CRITERIA /25 MPH/. THUS NO HEADLINES TODAY...BUT
WILL MENTION IN HWO AND HIGHLIGHT IN FIRE WEATHER FORECAST. DRYNESS
OF FUELS ALSO SOMEWHAT IN QUESTION OVER NRN IA. USED AS A PROXY FOR
FARTHER WEST WHERE CLIMATE DATA IS MORE QUESTIONABLE...MASON CITY
HAS HAD WETTEST METEOROLOGICAL SPRING TO DATE.
TUESDAY LOOKS TO BE HOTTER AND MUCH DRIER THAN PREVIOUSLY
ANTICIPATED AS MODELS OVERDOING THE SURFACE DEW POINTS ACROSS
CENTRAL IOWA. MIXING UP TO 3000 TO 3500 FEET BY TUESDAY AFTERNOON
WILL RESULT IN DEW POINTS IN THE UPPER 40S TO THE LOWER 50S.
HENCE...RH VALUES ARE FORECAST TO DROP TO 25 PERCENT OR LESS
GENERALLY ALONG AND WEST OF INTERSTATE 35. TEMPS WILL RAPIDLY
INCREASE IN THE MORNING AND THE 25 PERCENT RH VALUES LOOK TO BE
REALIZED BY AROUND NOON. SOUTHWEST WINDS GUSTING TO 30 TO 35 MPH
BY THE AFTERNOON. SO WITH THE LOW RH...GUSTY WINDS...AND HOT
TEMPS...BORDERLINE POTENTIAL FOR A RED FLAG WARNING ACROSS WESTERN
PORTIONS OF THE FORECAST AREA.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...REV
SHORT TERM...SMALL
LONG TERM...PODRAZIK
AVIATION...SMALL
FIRE WEATHER...SMALL/PODRAZIK
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
154 PM EDT MON MAY 13 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL REMAIN CENTERED OVER THE LOWER
MISSISSIPPI VALLEY TODAY...AS A TROUGH OF LOW PRESSURE PUSHES
THROUGH THE NORTHEAST STATES. THIS PATTERN WILL BRING WELL BELOW
NORMAL TEMPERATURES FOR THE MIDDLE OF MAY. THE HIGH WILL BUILD
INTO THE REGION TONIGHT INTO TUESDAY...AND WILL SLIDE OFF THE
COAST BY TUESDAY NIGHT. MUCH WARMER TEMPERATURES WILL RETURN
WEDNESDAY AND PERSIST INTO THE UPCOMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST SURFACE ANALYSIS SHOWS AN ELONGATED ~1026 MB SURFACE
HIGH SITUATED OVER THE LOWER MS VLY THIS MORNING...WITH A TROUGH
OF LOW PRESSURE DEEPENING OFF THE SC COAST IN RESPONSE TO A STRONG
UPPER TROUGH FROM THE GREAT LAKES SOUTH INTO THE SE CONUS.
MID/HIGH CLOUDS CONTINUE TO OVERSPREAD SE VA/NE NC IN RESPONSE TO
THE LOW OFF THE COAST WHILE MOSTLY SUNNY CONDITIONS PREVAIL
ELSEWHERE...ALTHOUGH THE LATEST VISIBLE IMAGERY INDICATES THE
EARLY STAGES OF CU DEVELOPMENT.
FOR TODAY...A POTENT MID LEVEL SHORTWAVE...CURRENTLY DIVING SOUTH
THROUGH EASTERN OH/WESTERN PA (AND PRODUCING LIGHT SN IN NW PA) WILL
PUSH SSE INTO SOUTH CENTRAL VA AND NE NC BY 00Z THIS EVENING.
WHILE THIS WILL CONTINUE TO DEEPEN THE COASTAL LOW...BULK OF
MOISTURE ASSOCIATED WITH THIS SHOULD STAY OFF THE COAST (PERHAPS
BRINGING A LIGHT SHRA TO THE OUTER BANKS). HOWEVER...DESPITE A
VERY DRY AIRMASS BELOW 800 MB...THE STRONG VORT MAX/PV ANOMALY
DIVES AROUND THE BACK-SIDE OF THE PARENT TROUGH DURING AFTER 18Z
THIS AFTN. THIS IS FORECAST TO DROP 500MB HEIGHTS TO -2 TO -3 ST
DEV BELOW THE MEAN PER 13/00Z GEFS. ADDITIONALLY...LOW AND MID
LEVEL LAPSE RATES WILL BE STEEP WITH COLD AIR ALOFT. GIVEN
THIS...A BKN-OVC SC DECK AROUND 6 K FT IS EXPECTED TO DEVELOP BY
MID AFTERNOON. RADAR WILL PROBABLY SHOW SOME ECHOES ACRS MUCH OF
THE CWA BETWEEN ABOUT 19Z AND 00Z. THE DRY LOW LEVELS (DEW PTS IN
UPPER 20S TO MID 30S) WILL GENLY INHIBIT MUCH OF A CHC FOR
MEASURABLE PRECIP TODAY...BUT GIVEN THE STRONG FORCING AND THE
INCOMING 13/12Z NAM AND HRRR HAVE DECIDED TO CHANGE WEATHER
WORDING FROM PROBABILITY (SLIGHT CHANCE) TO AREAL COVERAGE
(ISOLATED) BUT WILL MAINTAIN A 20 POP. ADDITIONALLY...ISOLATED
POPS HAVE BEEN EXTENDED INTO SE VA/NE NC FOR THE LATE
AFTERNOON/EARLY EVENING BASED ON THE AFOREMENTIONED DATA.
850MB TEMPERATURES DROP TO AROUND -1 C NORTH TO +1 C SOUTH THIS
AFTN...AROUND -2 ST DEV BELOW NORMAL. FULLY MIXED...EXPECT MAX
TEMPS TO RANGE MAINLY FROM THE LOWER TO MID 60S (ABOUT 1.5 TO 2 STD
DEV BELOW SEASONAL MEANS). DAYTIME HIGHS MAY BE REACHED AROUND
MIDDAY BEFORE DROPPING A FEW DEGREES IN THE MID-LATE AFTERNOON AS
CLOUD COVER INCREASES.
NEXT ISSUE WILL BE POTENTIAL RECORD LOWS EARLY TUE MORNING (SEE
CLIMATE SECTION). HAVE ADDED PATCHY FROST TO MUCH OF THE CWA WEST
OF I-95...ALTHOUGH EVEN EAST OF I-95 INTO THE INTERIOR OF SE/E VA
SOME AREAS WILL LIKELY DROP INTO THE UPPER 30S. AT THIS TIME...DE-
COUPLING NOT LIKELY TO OCCUR UNTIL AFTER 06Z...SO DO NOT ANTICIPATE
FROST TO BE WIDESPREAD ENOUGH TO WARRANT A FROST ADSY...ALTHOUGH
IF CLEARING/DE-COUPLING LOOKS TO OCCUR EARLIER...DA SHIFT MAY
CONSIDER ONE FOR PORTIONS OF THE CWA. LOWS IN THE MID TO UPPER 30S
ALONG/WEST OF I-95 AND IN MD...MID 40S IMMEDIATE COAST OF SE VA/NE
NC.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
THE HIGH SLOWLY DRIFTS OVER THE AREA TUESDAY AND THEN OFFSHORE
TUESDAY NIGHT. 850MB TEMPS REMAIN AROUND -2 TO -3 ST DEV BELOW
NORMAL SO HIGHS WILL REMAIN COOL...BUT SHOULD BE SLIGHTLY MILDER
(~ -1.5 ST DEV) DUE TO MORE SOLAR INSOLATION (MAINLY 65-70). HIGH
CLOUDS SHOULD BEGIN TO INCREASE LATER TUESDAY AND ESPECIALLY
TUESDAY NIGHT AS TEMPERATURES ALOFT BEGIN TO INCREASE RAPIDLY AS
RIDGING BUILDS IN FROM THE WEST. MUCH MILDER TUE NIGHT W/ LOWS
PRIMARILY IN THE UPPER 40S TO LWR 50S.
ON WED...SKIES BEGIN PARTLY TO MOSTLY CLOUDY WITH GRADUAL CLEARING
FROM SW TO NE THROUGH THE LATE MORNING AND AFTN. A RATHER DRAMATIC
SHIFT FROM COOL CONDITIONS TUE TO WARMER THAN AVG WX BY WED AFTN AS
850 MB TEMPS WARM BY NEARLY 15 C IN A 24 HR PERIOD. ONLY CAVEAT TO
WARMING TREND COULD BE IF CLOUD COVER DOES NOT BREAK (POSSIBLE
IF A BOUNDARY WERE TO DEVELOP). HIGHS SHOULD RANGE FROM THE UPPER
60S/LWR 70S ALONG THE IMMEDIATE COAST...TO 75-80 IMMEDIATELY
INLAND...TO THE MID 80S ALONG/W OF I-95. WILL NEED TO WATCH
POTENTIAL FOR ISO TSTMS (ESP NORTH) BY LATE AFTN IN WNW FLOW ALOFT
WITH AMPLE CAPE DEVELOPING ACRS THE INTERIOR OF THE CWA (FOR NOW
KEPT FCST MAINLY DRY THRU 00Z/THU).
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A BOUNDARY WILL LIFT THRU THE REGION AND OFFSHR WED NGT THRU THU
MORNG. AT THIS TIME...WILL HAVE CHC TSRA/SHRA MAINLY OVER NE
SECTIONS OF THE CWA DURING THIS PERIOD. WARM AND SOMEWHAT HUMID
CONDITIONS THEN EXPECTED FOR THU THRU SUN...WITH SLGT OR SML CHCS
FOR MAINLY AFTN/EVENG SHOWERS OR TSTMS...AS WEAK BOUNDARIES OR
TROFS DEVELOP AND MOVE ACRS THE AREA IN WNW FLO ALOFT. MIN TEMPS
WILL MAINLY RANGE FM THE UPR 50S TO LWR 60S THRU THE PERIOD. MAX
TEMPS WILL GENERALLY RANGE FM THE UPR 70S TO MID 80S.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AN UPPER LEVEL TROUGH AXIS WILL SWING A SHORTWAVE ACROSS THE MID
ATLANTIC REGION FROM NW TO SE THROUGH THE REMAINDER OF TODAY INTO
EARLY THIS EVENING. TAF SITES WILL MAINLY EXPERIENCE BKN CIGS AT TO
ABOVE 7000 FT AGL ALTHOUGH VERY LIGHT RAIN SHOWERS CANNOT BE
COMPLETELY RULED OUT DURING THIS TIMEFRAME. IF SHOWERS OCCUR...THEY
WILL HAVE VERY MINIMAL IMPACTS AND WILL KEEP ANY MENTION OUT OF
AREA TAFS. NW-N SFC WINDS WILL BE AROUND 10 KT WITH OCCASIONAL
GUSTS UP TO 20 KT THROUGH AT LEAST 13/2300Z...BUT WINDS ALOFT WILL
BE 20+ KT AND INCREASING WITH HEIGHT OVER THE NEXT 24 HOURS.
UNSETTLED NW FLOW BEHIND THE EXITING TROUGH WILL ALLOW SCT CU TO
DEVELOP LATE TUE MORNING THROUGH TUE AFTN (ONCE AGAIN AROUND
7000 FT AGL). AN UPSTREAM HIGH/THIN CIRRUS SHIELD FROM A LOW IN
THE UPPER GREAT LAKES REGION SHOULD ALSO BE ABLE TO STREAM ACROSS
THE REGION ON TUE. AS THIS SYSTEM MOVES INTO SE CANADA ON WED...A
BOUNDARY WILL BE DRAGGED ACROSS THE REGION AND MAY PROVIDE JUST
ENOUGH INSTABILITY FOR AFTN SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SCA OVER THE BAY WILL BE ALLOWED TO EXPIRE AT 4 AM AS WINDS
ASSOCIATED WITH A WEAK SURGE ARE NOW STARTING TO FALL TO 10-15 KT.
THESE WINDS WILL CONTINUE THRU THE DAY TDY AS SFC HI PRES SLOWLY
BLDS TOWARDS THE REGION. NWRLY FLOW PERSISTS TNGT WITH THE HI
CENTERED JUST WEST OF THE AREA...AND EXPECT ANOTHER ROUND OF 15-20
KT WINDS OVER THE BAY WITH YET ANOTHER SURGE. SCA TIMING WILL BE
FROM 7 PM TO 7 AM TUE MRNG. EXPECT 15-20 KT OVER COASTAL WATERS AS
WELL WITH 3-4 FT SEAS. HI PRES MOVES DIRECTLY OVER THE AREA TUE AFTN
WITH WINDS AOB 10 KT. SOUTHERLY FLOW RETURNS TUE NGT AND WED AS THE
HI SLIDES OFFSHORE. SEAS WILL APPROACH 5 FT OVER NORTHERN COASTAL
WATERS. ANOTHER FRNT DROPS INTO THE AREA DURING THE SECOND HALF OF
THIS WEEK WITH GENRLY SUB-SCA CONDS EXPECTED.
&&
.CLIMATE...
RECORD LOW TEMPERATURES WILL BE POSSIBLE TUESDAY MORNING (MAY 14TH):
RECORD LOWS FOR MAY 14TH:
RICHMOND....40 (1941)
NORFOLK.....43 (2007)
SALISBURY...32 (2007)
ELIZ CITY...41 (2007)
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 AM EDT
TUESDAY FOR ANZ630>632-634.
&&
$$
SYNOPSIS...LKB
NEAR TERM...AJZ/LKB
SHORT TERM...AJZ/LKB
LONG TERM...TMG
AVIATION...BMD
MARINE...MAS
CLIMATE...AKQ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
352 PM EDT MON MAY 13 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 351 PM EDT MON MAY 13 2013
TWO WAVES/DISTURBANCES WILL BE THE FOCUS FOR THE FORECAST...WITH
THE FIRST ONE AFFECTING THE AREA TONIGHT AND THE OTHER TOMORROW
AFTERNOON/EVENING.
LATEST WV IMAGERY AND RUC ANALYSIS SHOWS THE AREA UNDER RIDGING
ALOFT AS THE UPPER TROUGH THAT HAD BEEN AFFECTING THE AREA THIS
WEEKEND SHIFTING EAST ACROSS QUEBEC AND AN UPPER RIDGE OVER THE
WESTERN CONUS. THERE IS A DECENT AMOUNT OF MOISTURE ROUNDING THE
RIDGE WITH A 996MB LOW JUST TO THE WEST OF LAKE WINNIPEG. CLOSER TO
HOME...SKIES WERE CLEAR OVER MUCH OF UPPER MICHIGAN THIS
MORNING...BUT INCREASING MID-HIGH CLOUDS ARE SPREADING ACROSS THE
AREA THIS AFTERNOON. BAND OF RAIN IS STARTING TO MOVE INTO WESTERN
LAKE SUPERIOR AT THIS TIME AND IS ASSOCIATED WITH A THIN AREA OF
800-500MB MOISTURE AND 700MB F-GEN.
EXPECT THE BAND TO CONTINUE EAST-SOUTHEAST THIS EVENING AS THE
700MB F-GEN AND BROAD 850-700MB WARM AIR ADVECTION CONTINUE.
BUT...WITH THE 500MB SHORTWAVE AND ASSOCIATED HEIGHT FALLS SHIFTING
EAST THROUGH ONTARIO AND WELL NORTH OF THE AREA ALONG WITH BEING
UNDER THE WRONG AREA OF THE UPPER JET /RIGHT EXIT/ THE BETTER
FORCING ISN/T OVER THE AREA. PLUS...WITH THE DRY AIR IT WILL BE
RUNNING INTO...WONDERING IF THAT WILL LIMIT THE INTENSITY SOME.
WITH AS PERSISTENT AS IT HAS BEEN TODAY...DID BUMP UP POPS A
TOUCH TO GET MORE CHANCE/SCATTERED WORDING IN FOR THIS
EVENING...BUT BASED OFF THE LIMITED RAIN AMOUNTS SEEN UPSTREAM
/TRACE TO A COUPLE HUNDREDTHS/ DIDN/T WANT TO GO MUCH ABOVE THAT. AS
ADDITIONAL 850-700MB MOISTURE SLIDES SOUTHEAST ACROSS THE EASTERN
CWA TONIGHT...WOULD THINK THE PRECIPITATION CHANCES SHOULD INCREASE
SOME OVERNIGHT. THERE IS LITTLE OR NO INSTABILITY WITH THIS PASSING
WAA...AS MID LEVEL LAPSE RATES ARE ONLY AROUND 3-5 C/KM...SO WILL
KEEP THUNDER OUT OF THE FORECAST. WITH THE BETTER CONSISTENCY IN
THIS MOISTURE ARRIVING OVER THE EAST...DID BUMP UP VALUES TO HIGH
CHANCE POPS THERE.
EXPECT TO SEE A BRIEF REPRIEVE ON TUESDAY MORNING BEHIND THE INITIAL
AREA OF WAA TONIGHT. THIS WILL LIKELY PRODUCE SOME BREAKS OR
CLEARING OVER AT LEAST THE WEST HALF OF THE CWA DURING THE MORNING
HOURS BEFORE MID-HIGH CLOUDS STREAM BACK INTO THE AREA. THEN...THE
SHORTWAVE THAT IS CURRENTLY ENTERING THE PACIFIC NORTHWEST WILL BE
MOVING EAST-NORTHEAST ALONG THE US/CANADIAN BORDER AND BE NEAR LAKE
WINNIPEG BY 18Z TUESDAY. WARM AIR ADVECTION WILL AGAIN BE ON THE
INCREASE FROM WEST TO EAST DURING THE AFTERNOON. MOISTURE WILL ALSO
BE LIMITED AS IT MOVES THROUGH THE AREA DURING THE AFTERNOON. BEST
MOISTURE AND CLOSEST PROXIMITY TO THE SHORTWAVE WILL BE OVER THE
NORTHWEST HALF OF THE CWA...SO WILL HAVE HIGHEST POPS THEIR DURING
THE LATTER PART OF THE AFTERNOON. QPF/REFLECTIVITY FROM HIGH
RESOLUTION MODEL RUNS SEEM TO MATCH THIS IDEA AND LEADS TO GREATER
CONFIDENCE.
ELEVATED INSTABILITY IS MARGINAL ALONG/NORTH THE WARM FRONT...WITH
THE BEST INSTABILITY FARTHER SOUTHWEST AND AHEAD OF THE COLD
FRONT. THIS IS LARGELY DUE TO THE MID-LEVEL LAPSE RATES STRUGGLING
TO GET ABOVE 6C/KM. THUS...THUNDER POTENTIAL WILL BE SLIM THROUGH
THE AFTERNOON HOURS. IF ANY ELEVATED THUNDERSTORMS
DEVELOP...WOULDN/T EXPECT THEM TO BE TOO STRONG...AS EFFECTIVE SHEAR
VALUES WILL LIKELY BE BELOW 30KTS THROUGH 00Z ACROSS ALL BUT THE FAR
SOUTHWEST CWA.
AFTER A COOL WEEKEND...TEMPERATURES HAVE STARTED TO REBOUND TODAY
AND EXPECT IT TO CONTINUE ON TUESDAY. THE WARM AIR ADVECTING INTO
THE AREA ON TUESDAY ALONG WITH INCREASING SOUTHERLY FLOW SHOULD LEAD
TO HIGHS IN THE LOWER 70S OVER THE FAR WEST AND A GRADIENT TO THE
50S OVER THE EAST HALF.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 351 PM EDT MON MAY 13 2013
MUCH OF THIS PERIOD WILL BE MARKED BY THE PRESENCE OF A 70KT OR
GREATER 250MB JET OVER UPPER MICHIGAN AND/OR LAKE SUPERIOR...AT
LEAST FROM TUESDAY NIGHT THROUGH SATURDAY MORNING. THIS WILL KEEP
THE AREA IN A RELATIVELY BUSY WEATHER PATTERN...IN BETWEEN THE DOME
OF HOT AIR OVER MUCH OF THE WESTERN HALF OF THE NATION...AND COLDER
AIR RESIDING OVER CANADA.
WE WILL START OUT TUESDAY NIGHT WITH A STACKED 500MB TROUGH-SFC LOW
SET UP JUST NORTH OF CYRL IN WESTERN MANITOBA. A COLD FRONT WILL
EXTEND S FROM THE SFC LOW...THROUGH THE EASTERN THIRD OF MN TO A
SECONDARY SFC LOW/TRIPLE POINT THAT MAY BE DEVELOPING NEAR KDLH.
THE LOCATION OF THE WARM FRONT IS KEY...LIKELY SET UP FROM THE
ARROWHEAD OF MN DOWN AND NEAR THE WI BORDER OF UPPER MI AT 00Z
WEDNESDAY. AS IS TYPICAL...THESE SPLITTING SYSTEMS CAN DEVELOP AND
ROB US OF MOISTURE...AS CONVECTION POPS UP OVER WI. EXPECT
WAA...LIMITED FORCING WILL LIKELY PERSIST...WITH MUCH OF THE BEST
FORCING CLOSER TO THE MAIN SFC/500MB TROUGH ACROSS ONTARIO /WHERE AN
AVERAGE QUARTER OF AN INCH OR MORE OF RAIN IS EXPECTED/. WE LOOK TO
BE IN A PRETTY CAPPED ENVIRONMENT...WITH THE BEST CHANCE FOR ANY
STRONGER SHOWERS OR THUNDERSTORMS OVER SOUTH CENTRAL AND EASTERN
UPPER MI DURING THE LATE EVENING HOURS...AND EVEN THEN LIKELY
ELEVATED ABOVE THE DRY AIR. THE SOUTHERN LOW/COLD FRONT WILL BE OVER
EASTERN UPPER MI/LAKE SUPERIOR BY 09Z WEDNESDAY...AND EAST OF UPPER
MI BY 12Z.
COOLER/DRIER AIR WILL SWEEP IN FOR WEDNESDAY...WITH 850MB TEMPS
FALLING FROM A MAX 14-18C OVERNIGHT TO AN AVERAGE 7-8C DURING THE
DAY WEDNESDAY. PW VALUES FALL TO 0.37 TO 0.44IN...OR 60-70 PERCENT
OF NORMAL...WITH THE LOWEST VALUES AWAY FROM THE KEWEENAW PENINSULA
AND EXTREME S CENTRAL UPPER MI. EXPECT A MORE MODERATED AIRMASS FROM
MUNISING EASTWARD AS MORE MOIST AIR SLIDES IN NEAR THE SHORELINE. A
WORST CASE SCENARIO...WITH THE NAM MIXING UP TO 650-700MB DURING THE
AFTERNOON HOURS...DEW POINTS MIXING DOWN INTO THE UPPER 20S
/F/ WOULD RESULT IN AFTERNOON MIN RH VALUES OF 19-25 PERCENT FROM
JUST E OF IWD TO NORTHERN DELTA COUNTY...WITH GUSTS 25-30KTS. ON A
POSITIVE NOTE...THE LATEST MODEL RUNS ARE NOT QUITE AS STRONG WITH
THE WINDS. WILL NEED TO WAIT AND SEE IF THIS TREND HOLDS. IF
LIMITED...OR NO...PRECIPITATION FALLS TUESDAY NIGHT...FIRE CONCERNS
WILL BE ELEVATED.
BEHIND THE ELONGATED LOW SHIFTING EAST INTO QUEBEC WEDNESDAY
NIGHT...DRY WEATHER WILL REMAIN THROUGH FRIDAY MORNING...WITH COOL
WEST TO NORTHWEST FLOW LINGERING. EXPECT THE RIDGE OF HIGH PRESSURE
TO BE DIRECTLY OVERHEAD ON THURSDAY...WITH LIGHT WINDS AND LAKE
BREEZES EXPECTED.
OUR NEXT WEATHER MAKER WILL BE ORGANIZING ACROSS THE CENTRAL PLAINS
FRIDAY NIGHT THROUGH SATURDAY...BEFORE SHIFTING TOWARD MN AND IA
SATURDAY NIGHT. THE SFC LOW WILL SIT AND SPIN BEFORE FINALLY EXITING
NORTHEASTWARD ACROSS W LAKE SUPERIOR AROUND 06Z MONDAY AND SOUTHERN
ONTARIO DURING THE DAY MONDAY...AS THE 500MB TROUGH/LOW DIVES ACROSS
THE NORTHERN PLAINS SUNDAY INTO SUNDAY NIGHT. ADDED TS CHANCES
SATURDAY THROUGH MONDAY MORNING...BEFORE THE END TO THE BULK OF
MOISTURE. AT THIS POINT IT LOOKS LIKE THERE WILL BE A GOOD CHANCE OF
SOAKING RAIN OVER THE FAR W PORTIONS OF UPPER MI FRIDAY NIGHT
THROUGH SATURDAY...WITH ANOTHER ROUND POSSIBLE LATER SUNDAY INTO
MONDAY AS THE COLD FRONT SWINGS THROUGH.
OTHER THAN SUNDAY TIMING DIFFERENCES BETWEEN THE 12Z RUNS OF THE GFS
AND ECMWF...THE FCST MODELS ARE IN NORMAL TO SLIGHTLY ABOVE NORMAL
AGREEMENT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 137 PM EDT MON MAY 13 2013
EXPECT VFR CONDITIONS AT ALL THREE SITES THROUGH THE PERIOD. CLOUDS
WILL BE ON THE INCREASE WITH LOWERING CEILINGS THROUGH THIS
AFTERNOON AND EVENING...AS AN UPPER LEVEL DISTURBANCE PASSES
THROUGH. AS THIS DISTURBANCE MOVES THROUGH...THERE IS THE POTENTIAL
FOR SOME SHOWERS BUT THEY SHOULDN/T AFFECT VISIBILITIES DUE TO THE
5KFT PLUS BASES AND GENERALLY LIGHT RAIN. HAVE THE GREATEST
CONFIDENCE OF THEM OCCURRING NEAR KSAW...BUT MENTIONED THEM FOR ALL
THREE SITES. THIS DISTURBANCE WILL SHIFT EAST OVERNIGHT AND THERE
ARE SOME HINTS AT PATCHY FOG OR LOW CLOUDS OVER THE WEST. BUT WITH
LIMITED RAINFALL EXPECTED...EXISTING DRY LOW LEVELS AND
STRONG WINDS ALOFT...WILL LEAVE OUT MENTION. TOMORROW MORNING SHOULD
BE QUIET...WITH ANOTHER INCREASE IN MID-HIGH CLOUDS AHEAD OF THE
NEXT DISTURBANCE. FINALLY...WILL KEEP MENTION OF LLWS IN FOR
KIWD/KSAW THIS EVENING AND EARLY OVERNIGHT AS THE DISTURBANCE MOVES
THROUGH.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 351 PM EDT MON MAY 13 2013
HIGH PRESSURE WILL DEPART THE AREA THIS EVENING. THIS WILL LEAD TO
INCREASING SOUTHERLY FLOW TONIGHT INTO TUESDAY AHEAD OF A LOW
PRESSURE SYSTEM MOVING EAST THROUGH SOUTHERN CANADA. AT THIS
POINT...THE INCREASING WARM AIR ABOVE THE SURFACE SHOULD LIMIT GUST
TO 20KTS IN MOST LOCATIONS FOR OVERNIGHT TONIGHT AND TUESDAY.
DISPITE A COUPLE OF SIGNIFICANT SYSTEMS PUSHING THROUGH THE AREA
TUESDAY-TUESDAY NIGHT...AND AGAIN THIS WEEKEND...WINDS ARE CURRENTLY
ANTICIPATED TO REMAIN BELOW 30KTS. IT IS THAT TIME OF YEAR
AGAIN...THERE WILL BE A ROUND OF THUNDERSTORMS POSSIBLE TUESDAY
AFTERNOON OVER WESTERN LAKE SUPERIOR...PUSHING EASTWARD OVERNIGHT
AND ENDING EARLY WEDNESDAY. ANOTHER ROUND OF THUNDERSTORMS WILL BE
POSSIBLE WEST ON SATURDAY/SATURDAY NIGHT...AND ACROSS ALL OF LAKE
SUPERIOR SUNDAY THROUGH MONDAY MORNING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...KF
AVIATION...SRF
MARINE...SRF/KF
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1257 PM CDT MON MAY 13 2013
.SYNOPSIS...
ISSUED AT 334 AM CDT MON MAY 13 2013
AT H5 RIDGE OVER THE WESTERN CONUS CLOSED LOW OVER THE GREAT LAKES
WITH TROUGH INTO THE SOUTHEAST CONUS.
&&
.UPDATE...
ISSUED AT 1256 PM CDT MON MAY 13 2013
HAVE DONE AN UPDATE ON THE FORECAST TO ADJUST TEMPERATURES
SLIGHTLY TODAY. AT 17Z...OBSERVATIONS INDICATING A SURFACE TROUGH
ROUGHLY FROM KMCK TO K9V9 IN SD. LOCATIONS TO THE EAST ARE A BIT
COOLER WITH WINDS FROM THE SOUTH...WHILE WEST-NORTHWEST WINDS ON
THE WEST SIDE OF WERE HELPING TO ENHANCE WARMING. DESPITE CIRRUS
VEIL ACROSS THE FORECAST AREA TEMPERATURES HAVE MANAGED TO RISE
INTO THE MID AND UPPER 80S BY EARLY THIS AFTERNOON. STILL WILL SEE
TEMPERATURES IN THE 90S FOR THE FORECAST AREA THIS AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT MON MAY 13 2013
MODELS IN FAIR AGREEMENT. MAIN CONCERNS WILL BE RECORD HIGHS FOR
WESTERN NEBRASKA TODAY. RECORD AT LBF 91 FOR TODAY. LOT OF CIRRUS
PUSHING OVER THE RIDGE THIS MORNING. MODELS ALWAYS TEND TO UNDER
ESTIMATE THIS. 850MB TEMPERATURES AROUND 25C WHICH WOULD TRANSLATE
TO LOW 90S. RUC COMING UP WITH 95 FOR NORTH PLATTE WHERE MORE
INSOLATION EXPECTED AND WARM FRONT MAKING BIG PUSH. SOME CONVECTION
EXPECTED ON THE EASTERN PLAINS OF WYOMING AND COLORADO LATE THIS
AFTERNOON INTO EARLY EVENING...BUT WILL STRUGGLE TO MOVE INTO THE
NEBRASKA PANHANDLE AND HAVE LEFT THE FORECAST DRY FOR NOW.
TEMPERATURES TO STAY WARM WITH WAA AND SOUTHERLY FLOW TONIGHT
AHEAD OF THE TUESDAY SYSTEM DROPPING ACROSS THE NORTHERN PLAINS.
LOWS EXPECTED IN THE 50S AND 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 334 AM CDT MON MAY 13 2013
A HOT DAY STILL ON TAP FOR TUESDAY...ESPECIALLY ACROSS CENTRAL INTO
SOUTHWEST NEBRASKA. SOME TIMING DIFFERENCES REMAIN WITH THE FRONTAL
PASSAGE. THE 13/00Z NAM CONTINUES TO OFFER THE FASTEST
SOLUTION...AND HAS THE FRONT MOVING INTO CENTRAL AND SOUTHWEST
NEBRASKA BY EARLY AFTERNOON. THE ECMWF AND GFS ARE SLOWER AND BRING
THE FRONT IN TOWARD EVENING. THE NAM COULD BE ONTO SOMETHING...AS IT
MAY BE FASTER AS A RESULT OF A CONVECTIVE COMPLEX ROLLING ACROSS ND
EARLY TUESDAY MORNING. THIS COULD GIVE THE FRONT AN EXTRA PUSH WITH
ANY OUTFLOW FROM THE COMPLEX. A QUICK GLANCE AT THE NEW 13/06Z NAM
SUGGESTS THE FRONT NOW A TAD SLOWER. AT THIS TIME WILL STICK CLOSE
TO THE PREVIOUS FORECAST...WHICH SIDED TOWARD A SLOWER FRONTAL
PASSAGE. WILL CONTINUE THE HOT HIGH TEMPERATURES IN THE MID AND
UPPER 90S ACROSS SOUTHWEST INTO CENTRAL NEBRASKA AHEAD OF THE FRONT.
VERY FAVORABLE CONDITIONS DEVELOP JUST AHEAD OF THE FRONT FOR THE
HOT WEATHER...WITH WEST TO SOUTHWEST SFC WINDS AND DEEP MIXING UP
THROUGH 600 MB. A FIRE WEATHER CONCERN WILL DEVELOP AHEAD OF THE
FRONT AS WELL DUE TO THE DRY CONDITIONS AND DEEP MIXING. MODELS
INDICATE WIND SPEEDS NOT QUITE TO RED FLAG CRITERIA...BUT WINDS MAY
END UP BEING STRONGER THAN THE MODELS INDICATE DUE TO SUCH DEEP
MIXING AHEAD OF THE FRONT. ALSO A CONCERN WOULD BE ANY DRY LIGHTNING
ASSOCIATED WITH THE ISOLATED HIGH BASED STORMS THAT DEVELOP ALONG
THE FRONT AS THE CAP WEAKENS DURING THE MID TO LATE AFTERNOON.
SLIGHT CHANCES FOR STORMS CONTINUE TUESDAY NIGHT AS AN AREA OF
ELEVATED INSTABILITY DEVELOPS TO THE NORTH OF THE COLD FRONT WHICH
WILL BE MOVING SOUTH INTO KS. A WEAK UPPER LEVEL DISTURBANCE WILL
MOVE EAST ACROSS THE AREA AFTER MIDNIGHT AND INTERACT WITH THE
INSTABILITY...SO THE SLIGHT CHANCES FOR PRECIP WILL BE
MAINTAINED.
SOMEWHAT COOLER AND DRIER AIR FILTERS ACROSS THE AREA WEDNESDAY AS
THE COLD FRONT STALLS ACROSS KS.
THUNDERSTORM CHANCES BEGIN TO INCREASE THURSDAY AND THURSDAY NIGHT
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. THE FRONT WHICH STALLED
WEDNESDAY ACROSS KS...WILL BEGIN TO LIFT NORTH AS A WARM FRONT INTO
WESTERN AND NORTH CENTRAL NEBRASKA THURSDAY. AS THIS OCCURS...GULF
MOISTURE WILL SURGE NORTH INTO THE AREA. THE 13/00Z GFS INDICATES
H85 DEW PTS RISING INTO THE 10 TO 12C RANGE DURING THE DAY
THURSDAY...AND INCREASING FURTHER TO 13 TO 15C THURSDAY NIGHT AS THE
LOW LEVEL JET STRENGTHENS. AT THE SAME TIME...SEVERAL SUBTLE UPPER
LEVEL WAVES EJECT NORTHEAST ACROSS THE AREA FROM DEVELOPING WESTERN
CONUS UPPER TROUGH. THIS SET UP WOULD APPEAR FAVORABLE FOR
THUNDERSTORM DEVELOPMENT ACROSS WESTERN NEBRASKA DURING THE LATE
AFTERNOON...BECOMING MORE WIDESPREAD DURING THE EVENING AS THE
SOUTHERLY LOW LEVEL JET INTENSIFIES. THE GFS OFFERS JUST THIS
SCENARIO...WITH THE ECMWF SIMILAR BUT A LITTLE FARTHER EAST WITH THE
BETTER MOISTURE ACROSS CENTRAL NEBRASKA. NAM MODEL NOT QUITE OUT FAR
ENOUGH TO HELP WITH THIS FORECAST PERIOD YET. FOR NOW WILL NOT GET
CARRIED AWAY WITH POPS...WITH THE GFS PROBABLY A TAD ON THE MOIST
SIDE BOTH WITH THE AMOUNT OF MOISTURE AND QPF.
WITH THE UPPER TROUGH REMAINING TO OUR WEST THROUGH SATURDAY
NIGHT...ACTIVE WEATHER WILL CONTINUE. STILL TOO EARLY TO PIN DOWN
EXACTLY WHERE THE BEST FOCUS FOR THUNDERSTORMS WILL BE...BUT
DEVELOPMENT IN OR JUST EAST OF OUR FORECAST AREA SEEMS LIKELY BOTH
FRIDAY AND SATURDAY.
BY SUNDAY BOTH THE 13/00Z RUNS OF THE ECMWF AND GFS DRIVE A COLD
FRONT SOUTHEAST THROUGH THE AREA. THIS WOULD PLACE THE BEST FOCUS
FOR RAIN TO OUR EAST...BUT FOR NOW WILL MAINTAIN THE CHANCES GOING
IN CASE THE FRONT SLOWS SOMEWHAT.
TEMPERATURE WISE...WITH THE INCREASED CLOUD COVER AND MOISTURE...80S
SEEM REASONABLE THURSDAY THROUGH SATURDAY...WITH COOLER UPPER 60S
AND 70S BEHIND THE FRONT SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1222 AM CDT MON MAY 13 2013
VFR CONDITIONS WILL BE OBSERVED ACROSS NEBRASKA THROUGH TUESDAY
AFTERNOON. MAIN CONCERNS WILL BE WIND SHIFTS...AS WELL AS SOME
INCREASING WINDS BEHIND A COLD FRONT SET TO MOVE INTO NORTHERN
NEBRASKA TUESDAY MORNING. LOOKING FOR WINDS TO SHIFT TO THE
NORTHWEST BEHIND THE FRONT AND INCREASING WITH GUSTS TO 25 MPH.
THIS WILL IMPACT THE KVTN FORECAST IN THE MORNING...WHILE LOCATIONS
TO THE SOUTH SHOULD EXPECT TO SEE THIS SAME TREND LATER IN THE
AFTERNOON AND EVENING.
&&
.FIRE WEATHER...
ISSUED AT 334 AM CDT MON MAY 13 2013
WITH TEMPERATURES SOARING TODAY OVER WESTERN NEBRASKA AND DEWPOINTS
IN THE 30S AND 40S MINIMUM RELATIVE HUMIDITIES WILL FALL INTO THE
TEENS ACROSS WESTERN NEBRASKA...BASICALLY WHERE THEY HAVE BEEN THE
LAST SEVERAL DAYS. TUESDAY WILL BE SIMILAR AHEAD OF THE FRONT.
WINDS OVER NORTHERN NEBRASKA WILL BE 10 TO 15 MPH WITH SOME GUSTS
TO THE LOW 20S MAKING IT MARGINAL FOR HIGHLIGHTS. WILL HOLD OFF
FOR NOW. TUESDAY AHEAD OF THE FRONT ACROSS SOUTHWEST INTO CENTRAL
NEBRASKA...HIGHLIGHTS LOOK POSSIBLE...AS WINDS FROM THE SOUTHWEST
INCREASE DUE TO DEEP MIXING...AND DRY LIGHTNING IS POSSIBLE AS
WELL DUE TO THE HIGH BASED NATURE OF ANY STORM THAT WOULD HAPPEN
TO DEVELOP ALONG THE FRONT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BROOKS
SYNOPSIS...POWER
SHORT TERM...TAYLOR
LONG TERM...POWER
AVIATION...BROOKS
FIRE WEATHER...POWER
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1223 PM CDT MON MAY 13 2013
.SYNOPSIS...
ISSUED AT 334 AM CDT MON MAY 13 2013
AT H5 RIDGE OVER THE WESTERN CONUS CLOSED LOW OVER THE GREAT LAKES
WITH TROUGH INTO THE SOUTHEAST CONUS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CDT MON MAY 13 2013
MODELS IN FAIR AGREEMENT. MAIN CONCERNS WILL BE RECORD HIGHS FOR
WESTERN NEBRASKA TODAY. RECORD AT LBF 91 FOR TODAY. LOT OF CIRRUS
PUSHING OVER THE RIDGE THIS MORNING. MODELS ALWAYS TEND TO UNDER
ESTIMATE THIS. 850MB TEMPERATURES AROUND 25C WHICH WOULD TRANSLATE
TO LOW 90S. RUC COMING UP WITH 95 FOR NORTH PLATTE WHERE MORE
INSOLATION EXPECTED AND WARM FRONT MAKING BIG PUSH. SOME CONVECTION
EXPECTED ON THE EASTERN PLAINS OF WYOMING AND COLORADO LATE THIS
AFTERNOON INTO EARLY EVENING...BUT WILL STRUGGLE TO MOVE INTO THE
NEBRASKA PANHANDLE AND HAVE LEFT THE FORECAST DRY FOR NOW.
TEMPERATURES TO STAY WARM WITH WAA AND SOUTHERLY FLOW TONIGHT
AHEAD OF THE TUESDAY SYSTEM DROPPING ACROSS THE NORTHERN PLAINS.
LOWS EXPECTED IN THE 50S AND 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 334 AM CDT MON MAY 13 2013
A HOT DAY STILL ON TAP FOR TUESDAY...ESPECIALLY ACROSS CENTRAL INTO
SOUTHWEST NEBRASKA. SOME TIMING DIFFERENCES REMAIN WITH THE FRONTAL
PASSAGE. THE 13/00Z NAM CONTINUES TO OFFER THE FASTEST
SOLUTION...AND HAS THE FRONT MOVING INTO CENTRAL AND SOUTHWEST
NEBRASKA BY EARLY AFTERNOON. THE ECMWF AND GFS ARE SLOWER AND BRING
THE FRONT IN TOWARD EVENING. THE NAM COULD BE ONTO SOMETHING...AS IT
MAY BE FASTER AS A RESULT OF A CONVECTIVE COMPLEX ROLLING ACROSS ND
EARLY TUESDAY MORNING. THIS COULD GIVE THE FRONT AN EXTRA PUSH WITH
ANY OUTFLOW FROM THE COMPLEX. A QUICK GLANCE AT THE NEW 13/06Z NAM
SUGGESTS THE FRONT NOW A TAD SLOWER. AT THIS TIME WILL STICK CLOSE
TO THE PREVIOUS FORECAST...WHICH SIDED TOWARD A SLOWER FRONTAL
PASSAGE. WILL CONTINUE THE HOT HIGH TEMPERATURES IN THE MID AND
UPPER 90S ACROSS SOUTHWEST INTO CENTRAL NEBRASKA AHEAD OF THE FRONT.
VERY FAVORABLE CONDITIONS DEVELOP JUST AHEAD OF THE FRONT FOR THE
HOT WEATHER...WITH WEST TO SOUTHWEST SFC WINDS AND DEEP MIXING UP
THROUGH 600 MB. A FIRE WEATHER CONCERN WILL DEVELOP AHEAD OF THE
FRONT AS WELL DUE TO THE DRY CONDITIONS AND DEEP MIXING. MODELS
INDICATE WIND SPEEDS NOT QUITE TO RED FLAG CRITERIA...BUT WINDS MAY
END UP BEING STRONGER THAN THE MODELS INDICATE DUE TO SUCH DEEP
MIXING AHEAD OF THE FRONT. ALSO A CONCERN WOULD BE ANY DRY LIGHTNING
ASSOCIATED WITH THE ISOLATED HIGH BASED STORMS THAT DEVELOP ALONG
THE FRONT AS THE CAP WEAKENS DURING THE MID TO LATE AFTERNOON.
SLIGHT CHANCES FOR STORMS CONTINUE TUESDAY NIGHT AS AN AREA OF
ELEVATED INSTABILITY DEVELOPS TO THE NORTH OF THE COLD FRONT WHICH
WILL BE MOVING SOUTH INTO KS. A WEAK UPPER LEVEL DISTURBANCE WILL
MOVE EAST ACROSS THE AREA AFTER MIDNIGHT AND INTERACT WITH THE
INSTABILITY...SO THE SLIGHT CHANCES FOR PRECIP WILL BE
MAINTAINED.
SOMEWHAT COOLER AND DRIER AIR FILTERS ACROSS THE AREA WEDNESDAY AS
THE COLD FRONT STALLS ACROSS KS.
THUNDERSTORM CHANCES BEGIN TO INCREASE THURSDAY AND THURSDAY NIGHT
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. THE FRONT WHICH STALLED
WEDNESDAY ACROSS KS...WILL BEGIN TO LIFT NORTH AS A WARM FRONT INTO
WESTERN AND NORTH CENTRAL NEBRASKA THURSDAY. AS THIS OCCURS...GULF
MOISTURE WILL SURGE NORTH INTO THE AREA. THE 13/00Z GFS INDICATES
H85 DEW PTS RISING INTO THE 10 TO 12C RANGE DURING THE DAY
THURSDAY...AND INCREASING FURTHER TO 13 TO 15C THURSDAY NIGHT AS THE
LOW LEVEL JET STRENGTHENS. AT THE SAME TIME...SEVERAL SUBTLE UPPER
LEVEL WAVES EJECT NORTHEAST ACROSS THE AREA FROM DEVELOPING WESTERN
CONUS UPPER TROUGH. THIS SET UP WOULD APPEAR FAVORABLE FOR
THUNDERSTORM DEVELOPMENT ACROSS WESTERN NEBRASKA DURING THE LATE
AFTERNOON...BECOMING MORE WIDESPREAD DURING THE EVENING AS THE
SOUTHERLY LOW LEVEL JET INTENSIFIES. THE GFS OFFERS JUST THIS
SCENARIO...WITH THE ECMWF SIMILAR BUT A LITTLE FARTHER EAST WITH THE
BETTER MOISTURE ACROSS CENTRAL NEBRASKA. NAM MODEL NOT QUITE OUT FAR
ENOUGH TO HELP WITH THIS FORECAST PERIOD YET. FOR NOW WILL NOT GET
CARRIED AWAY WITH POPS...WITH THE GFS PROBABLY A TAD ON THE MOIST
SIDE BOTH WITH THE AMOUNT OF MOISTURE AND QPF.
WITH THE UPPER TROUGH REMAINING TO OUR WEST THROUGH SATURDAY
NIGHT...ACTIVE WEATHER WILL CONTINUE. STILL TOO EARLY TO PIN DOWN
EXACTLY WHERE THE BEST FOCUS FOR THUNDERSTORMS WILL BE...BUT
DEVELOPMENT IN OR JUST EAST OF OUR FORECAST AREA SEEMS LIKELY BOTH
FRIDAY AND SATURDAY.
BY SUNDAY BOTH THE 13/00Z RUNS OF THE ECMWF AND GFS DRIVE A COLD
FRONT SOUTHEAST THROUGH THE AREA. THIS WOULD PLACE THE BEST FOCUS
FOR RAIN TO OUR EAST...BUT FOR NOW WILL MAINTAIN THE CHANCES GOING
IN CASE THE FRONT SLOWS SOMEWHAT.
TEMPERATURE WISE...WITH THE INCREASED CLOUD COVER AND MOISTURE...80S
SEEM REASONABLE THURSDAY THROUGH SATURDAY...WITH COOLER UPPER 60S
AND 70S BEHIND THE FRONT SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1222 AM CDT MON MAY 13 2013
VFR CONDITIONS WILL BE OBSERVED ACROSS NEBRASKA THROUGH TUESDAY
AFTERNOON. MAIN CONCERNS WILL BE WIND SHIFTS...AS WELL AS SOME
INCREASING WINDS BEHIND A COLD FRONT SET TO MOVE INTO NORTHERN
NEBRASKA TUESDAY MORNING. LOOKING FOR WINDS TO SHIFT TO THE
NORTHWEST BEHIND THE FRONT AND INCREASING WITH GUSTS TO 25 MPH.
THIS WILL IMPACT THE KVTN FORECAST IN THE MORNING...WHILE LOCATIONS
TO THE SOUTH SHOULD EXPECT TO SEE THIS SAME TREND LATER IN THE
AFTERNOON AND EVENING.
&&
.FIRE WEATHER...
ISSUED AT 334 AM CDT MON MAY 13 2013
WITH TEMPERATURES SOARING TODAY OVER WESTERN NEBRASKA AND DEWPOINTS
IN THE 30S AND 40S MINIMUM RELATIVE HUMIDITIES WILL FALL INTO THE
TEENS ACROSS WESTERN NEBRASKA...BASICALLY WHERE THEY HAVE BEEN THE
LAST SEVERAL DAYS. TUESDAY WILL BE SIMILAR AHEAD OF THE FRONT.
WINDS OVER NORTHERN NEBRASKA WILL BE 10 TO 15 MPH WITH SOME GUSTS
TO THE LOW 20S MAKING IT MARGINAL FOR HIGHLIGHTS. WILL HOLD OFF
FOR NOW. TUESDAY AHEAD OF THE FRONT ACROSS SOUTHWEST INTO CENTRAL
NEBRASKA...HIGHLIGHTS LOOK POSSIBLE...AS WINDS FROM THE SOUTHWEST
INCREASE DUE TO DEEP MIXING...AND DRY LIGHTNING IS POSSIBLE AS
WELL DUE TO THE HIGH BASED NATURE OF ANY STORM THAT WOULD HAPPEN
TO DEVELOP ALONG THE FRONT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...POWER
SHORT TERM...TAYLOR
LONG TERM...POWER
AVIATION...BROOKS
FIRE WEATHER...POWER
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
138 PM CDT MON MAY 13 2013
.UPDATE...
ISSUED AT 1023 AM CDT MON MAY 13 2013
IN GENERAL EARLIER FORECAST IS BEHAVING FAIRLY WELL WITH A LITTLE
SLOWER DECREASE IN THE HIGH CLOUD COVER. STILL EXPECT WITH THE
CLOUDS THINNING OUT BY AFTERNOON THAT THE HEATING AND WARMING WILL
PUT TEMPERATURES CLOSE TO FORECAST HIGHS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT MON MAY 13 2013
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
WINDS WILL TAPER DOWN THIS EVENING AND TURN SOUTHERLY OVERNIGHT.
WITH THERMAL PROFILES CONTINUING TO WARM...IT WILL BE A MILD NIGHT
WITH LOWS IN THE MID 50S TO LOWER 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 347 AM CDT MON MAY 13 2013
A STRONG SOUTHERLY FLOW SETS UP ON TUESDAY OUT AHEAD OF A SURFACE
TROUGH/FRONTAL BOUNDARY WHICH WILL PUSH ACROSS THE AREA IN THE
AFTERNOON. MOISTURE LOOKS TO BE MINIMAL WITH THIS SYSTEM...SO
EXPECTING IT TO BE A DRY FRONTAL PASSAGE. IT WILL BE A VERY MIXY DAY
WITH STRONG SOUTHWESTERLY WINDS OUT AHEAD OF THE FRONT...AND STRONG
NORTHWESTERLY WINDS BEHIND THE FRONT. MODELS AGAIN SEEM TO BE
OVERDOING DEWPOINTS ON TUESDAY...MOST LIKELY OVER DOING
EVAPOTRANSPIRATION...AND PROGGING DEWPOINTS WELL INTO THE 50S.
INSTEAD USED THE MIXDOWN TOOL WHICH YIELDED A BETTER ESTIMATION OF
DEWPOINTS...GENERALLY IN THE 40S...WITH SOME MOISTURE POOLING ALONG
THE FRONTAL BOUNDARY...THOUGH STILL MAY BE SLIGHTLY TOO HIGH ON
VALUES. IN ANY EVENT...WITH THE STRONG WINDS AND AFTERNOON RELATIVE
HUMIDITY VALUES FLOATING AROUND 20 TO 25 PERCENT...ISSUED A FIRE
WEATHER WATCH FOR THE ENTIRE CWA. AS HAS BEEN ADVERTISED OF
LATE...TUESDAY WILL GENERALLY BE THE WARMEST DAY OF THE WEEK WITH
ALL MODELS PROGGING 850 MB TEMPERATURES IN THE LOWER TO MID 20S C
OVER OUR EAST IN THE AFTERNOON...SO KEPT WITH LOWER TO MID 90S
THERE. WITH COLD AIR ADVECTION BEHIND THE FRONT...IT WILL BE LITTLE
COOLER TO THE WEST...WITH HIGHS IN THE MID AND UPPER 80S.
COOLER AIR WILL FILTER INTO THE REGION ON TUESDAY NIGHT WITH WINDS
DYING OFF OVERNIGHT. LOWS LOOKING TO BE IN THE UPPER 40S TO MID 50S.
WEDNESDAY AND WEDNESDAY NIGHT APPEAR TO BE PLEASANT WITH WEAK HIGH
PRESSURE BUILDING INTO THE REGION...WITH HIGHS IN THE 70S AND LOWS
IN THE 50S.
FARTHER INTO THE EXTENDED...THURSDAY THROUGH SUNDAY...LOOKS TO BE A
FAIRLY ACTIVE PERIOD WITH A NEARLY ZONAL UPPER LEVEL FLOW AT THE
START OF THE PERIOD...TRANSITIONING TO RIDGING ON FRIDAY AS A TROUGH
BEGINS TO LIFT OUT OF THE WESTERN U.S. AND INTO THE AREA BY LATE IN
THE WEEKEND. THINK MOST OF THURSDAY WILL BE DRY AND LITTLE WARMER AS
A SOUTHERLY FLOW BEGINS TO RETURN TO THE REGION WITH HIGHS IN THE
MID AND UPPER 70S. CANNOT RULE OUT SCATTERED THUNDERSTORMS FOR
THURSDAY NIGHT AND FRIDAY WITH INCREASING THETA E ADVECTION INTO THE
REGION...THOUGH WOULD BE HARD TO PIN POINT EXACT TIMING ON ANY
CONVECTIVE DEVELOPMENT THIS FAR OUT. A BETTER CHANCE OF CONVECTION
WOULD APPEAR TO BE LIKELY ON FRIDAY NIGHT AS LOW PRESSURE BEGINS TO
LIFT OUT OF THE ROCKIES. WITH CONVECTIVE PARAMETERS INCREASING
DURING THAT TIME FRAME...SEVERE STORMS WOULD SEEM MORE
LIKELY...THOUGH MODELS ARE DIFFERING A BIT ON THE PLACEMENT OF A
BOUNDARY LAYING SOMEWHERE CLOSE TO OUR AREA ON FRIDAY NIGHT AND
SATURDAY. THE UPPER LEVEL TROUGH SWINGS THROUGH THE REGION ON
SUNDAY...KEEPING A CHANCE OF CONVECTION...WITH COOLER AIR BEGINNING
TO PULL IN BEHIND THE SYSTEM.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 108 PM CDT MON MAY 13 2013
VFR EXPECTED TO CONTINUE THROUGH 14/18Z EVEN AS COLD FRONT ENTERS
THE NORTHWEST CORNER OF THE AREA INCLUDING HON BY 14/18Z. SURFACE
GUSTS TO 25 TO 30 KNOTS FROM THE WEST TO SOUTHWEST IN SOUTHWEST MN
AND NORTHWEST IA WILL DECREASE BY 23Z BUT MAY REDEVELOP AFTER
14/15Z OVER THE AREA. WINDS WILL SHIFT TO THE NORTHWEST OVER THE
NORTHWEST CORNER OF THE AREA INCLUDING HON NEAR END OF PERIOD BY
14/18Z.
&&
.FIRE WEATHER...
ISSUED AT 138 PM CDT MON MAY 13 2013
RED FLAG WARNING HAS BEEN ISSUED FOR SOUTHWEST MN PART OF AND
NORTHWEST IA FOR THIS AFTERNOON AND CONTINUES UNTIL 6 PM CDT. THE
STRONG WINDS AND LOW RELATIVE HUMIDITIES WILL BE A PROBLEM AGAIN
TUESDAY...ONLY OVER ALL OF THE AREA. THE HIGHER DEW POINTS TUESDAY
WILL BE MORE THAN COMPENSATED FOR BY THE VERY WARM TO HOT
TEMPERATURES. THERE COULD BE SOMEWHAT OF A SLIGHT LULL NEAR THE
FRONT IN THE SHIFTING ZONE BUT FEEL THE WINDS WILL BE HIGH ENOUGH
CONTINUOUSLY ENOUGH TO UPGRADE THE FIRE WEATHER WATCH TO A RED FLAG
WARNING. THIS WILL BE FOR THE SAME TIME PERIOD THE WATCH WAS FOR. WE
HAVE ALREADY HAD FIRE ACTIVITY IN SOUTHWEST MN THIS AFTERNOON AND
THE SAME COULD HAPPEN ANYWHERE TUESDAY. RECENT GREENING OF GRASSES
HAS BEEN AT LOW LEVELS AND FIRES MAY NOT BE REAL QUICK TO
START...BUT MAY SPREAD VERY QUICKLY IN THE LINGERING DORMANT TALL
GRASSES.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR SDZ255>258.
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR MNZ900.
RED FLAG WARNING UNTIL 6 PM CDT THIS EVENING FOR MNZ900.
IA...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR IAZ300-301.
RED FLAG WARNING UNTIL 6 PM CDT THIS EVENING FOR IAZ301.
NE...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR NEZ249.
&&
$$
UPDATE...
SHORT TERM...MJF/JM
LONG TERM...JM
AVIATION...
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
111 PM CDT MON MAY 13 2013
.UPDATE...
ISSUED AT 1023 AM CDT MON MAY 13 2013
IN GENERAL EARLIER FORECAST IS BEHAVING FAIRLY WELL WITH A LITTLE
SLOWER DECREASE IN THE HIGH CLOUD COVER. STILL EXPECT WITH THE
CLOUDS THINNING OUT BY AFTERNOON THAT THE HEATING AND WARMING WILL
PUT TEMPERATURES CLOSE TO FORECAST HIGHS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT MON MAY 13 2013
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
OBVIOUSLY THE MAIN CONCERN TODAY IS FIRE WEATHER. TEMPERATURES WILL
BE WELL ABOVE SEASONAL NORMALS AS A SURFACE TROUGH OF LOW PRESSURE
MOVES EASTWARD ACROSS OUR FORECAST AREA. THIS SURFACE TROUGH WILL
CAUSE A WIND SHIFT FROM THE SOUTHWEST TO NORTHWEST BEFORE IT STALLS
OUT LATE IN THE DAY IN NORTHWEST IOWA. GIVEN THE WINDS OFF THE
SURFACE AND MIXING POTENTIAL...OUR ZONES IN IOWA AROUND THE IOWA
GREAT LAKES AND STORM LAKE AREAS...AS WELL AS SOME OF THE SOUTHERN
SECTIONS IN SOUTHWEST MINNESOTA...WILL PUSH RED FLAG CRITERIA BUT
PROBABLY ONLY FOR A COUPLE OF HOURS. THIS IS BECAUSE BETWEEN 21Z AND
00Z...THE WINDS SHOULD DECREASE A FAIR AMOUNT IN THE AXIS OF THE
SURFACE TROUGH WHICH IS RIGHT IN THOSE AREAS. THEREFORE IT WILL BE A
BREEZY TO MODERATELY WINDY DAY IN THOSE AREAS...GOOD FOR A VERY HIGH
FIRE DANGER...BUT POSSIBLY JUST NOT QUITE THERE FOR A BONAFIDE RED
FLAG WARNING. THE SAME HOLDS TRUE FOR BEHIND THE SURFACE TROUGH...
WHICH IS ALONG AND WEST OF THE JAMES RIVER VALLEY. MINIMUM HUMIDITY
VALUES WILL LIKELY REALLY TANK IN THOSE ZONES TO LESS THAN 20
PERCENT. HOWEVER IN OUR WESTERN ZONES THIS AFTERNOON...SUSTAINED
NORTHWEST SURFACE WINDS WILL LIKELY STAY LESS THEN 20 MPH MUCH OF
THE TIME...WITH GUSTS FREQUENTLY AROUND 25 TO 27 MPH. SO AGAIN...
JUST A BIT BELOW RED FLAG CRITERIA...BUT CERTAINLY ELEVATED FIRE
DANGER. THE ONE THING THAT COULD REALLY ALTER THIS SCENARIO
SIGNIFICANTLY IS IF THE MIXED LAYER WINDS WHICH ARE FORECAST TO BE
AROUND 25 KNOTS IN OUR FORECAST AREA...BECOME STRONGER THEN
ANTICIPATED. IF THAT HAPPENS...WE COULD GO RED FLAG OVER MANY AREAS.
CONCERNING HUMIDITY...MUCH OF THE MODEL DEW POINT GUIDANCE IS WAY
TOO HIGH. PRIMARILY BLENDED THE REALLY DRY RAP MODEL DEW POINTS INTO
CONSENSUS SHORT. THIS SEEMED TO GIVE REASONABLE VALUES...AS IT SEEMS
THAT EACH DAY WE CANNOT GO LOW ENOUGH ON THE DEW POINTS...AND THUS
THE HUMIDITY VALUES. RIGHT NOW...DEW POINTS ARE IN THE 30S WEST
RIVER...AND LOWER TO MID 40S IN SOUTH CENTRAL NEBRASKA. THEREFORE
LOOKING AT TRAJECTORIES EITHER FOR A SOUTHWEST WIND OR NORTHWEST
WIND...MADE SURE NOT TO GO ABOVE THOSE VALUES UPSTREAM.
WINDS WILL TAPER DOWN THIS EVENING AND TURN SOUTHERLY OVERNIGHT.
WITH THERMAL PROFILES CONTINUING TO WARM...IT WILL BE A MILD NIGHT
WITH LOWS IN THE MID 50S TO LOWER 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 347 AM CDT MON MAY 13 2013
A STRONG SOUTHERLY FLOW SETS UP ON TUESDAY OUT AHEAD OF A SURFACE
TROUGH/FRONTAL BOUNDARY WHICH WILL PUSH ACROSS THE AREA IN THE
AFTERNOON. MOISTURE LOOKS TO BE MINIMAL WITH THIS SYSTEM...SO
EXPECTING IT TO BE A DRY FRONTAL PASSAGE. IT WILL BE A VERY MIXY DAY
WITH STRONG SOUTHWESTERLY WINDS OUT AHEAD OF THE FRONT...AND STRONG
NORTHWESTERLY WINDS BEHIND THE FRONT. MODELS AGAIN SEEM TO BE
OVERDOING DEWPOINTS ON TUESDAY...MOST LIKELY OVER DOING
EVAPOTRANSPIRATION...AND PROGGING DEWPOINTS WELL INTO THE 50S.
INSTEAD USED THE MIXDOWN TOOL WHICH YIELDED A BETTER ESTIMATION OF
DEWPOINTS...GENERALLY IN THE 40S...WITH SOME MOISTURE POOLING ALONG
THE FRONTAL BOUNDARY...THOUGH STILL MAY BE SLIGHTLY TOO HIGH ON
VALUES. IN ANY EVENT...WITH THE STRONG WINDS AND AFTERNOON RELATIVE
HUMIDITY VALUES FLOATING AROUND 20 TO 25 PERCENT...ISSUED A FIRE
WEATHER WATCH FOR THE ENTIRE CWA. AS HAS BEEN ADVERTISED OF
LATE...TUESDAY WILL GENERALLY BE THE WARMEST DAY OF THE WEEK WITH
ALL MODELS PROGGING 850 MB TEMPERATURES IN THE LOWER TO MID 20S C
OVER OUR EAST IN THE AFTERNOON...SO KEPT WITH LOWER TO MID 90S
THERE. WITH COLD AIR ADVECTION BEHIND THE FRONT...IT WILL BE LITTLE
COOLER TO THE WEST...WITH HIGHS IN THE MID AND UPPER 80S.
COOLER AIR WILL FILTER INTO THE REGION ON TUESDAY NIGHT WITH WINDS
DYING OFF OVERNIGHT. LOWS LOOKING TO BE IN THE UPPER 40S TO MID 50S.
WEDNESDAY AND WEDNESDAY NIGHT APPEAR TO BE PLEASANT WITH WEAK HIGH
PRESSURE BUILDING INTO THE REGION...WITH HIGHS IN THE 70S AND LOWS
IN THE 50S.
FARTHER INTO THE EXTENDED...THURSDAY THROUGH SUNDAY...LOOKS TO BE A
FAIRLY ACTIVE PERIOD WITH A NEARLY ZONAL UPPER LEVEL FLOW AT THE
START OF THE PERIOD...TRANSITIONING TO RIDGING ON FRIDAY AS A TROUGH
BEGINS TO LIFT OUT OF THE WESTERN U.S. AND INTO THE AREA BY LATE IN
THE WEEKEND. THINK MOST OF THURSDAY WILL BE DRY AND LITTLE WARMER AS
A SOUTHERLY FLOW BEGINS TO RETURN TO THE REGION WITH HIGHS IN THE
MID AND UPPER 70S. CANNOT RULE OUT SCATTERED THUNDERSTORMS FOR
THURSDAY NIGHT AND FRIDAY WITH INCREASING THETA E ADVECTION INTO THE
REGION...THOUGH WOULD BE HARD TO PIN POINT EXACT TIMING ON ANY
CONVECTIVE DEVELOPMENT THIS FAR OUT. A BETTER CHANCE OF CONVECTION
WOULD APPEAR TO BE LIKELY ON FRIDAY NIGHT AS LOW PRESSURE BEGINS TO
LIFT OUT OF THE ROCKIES. WITH CONVECTIVE PARAMETERS INCREASING
DURING THAT TIME FRAME...SEVERE STORMS WOULD SEEM MORE
LIKELY...THOUGH MODELS ARE DIFFERING A BIT ON THE PLACEMENT OF A
BOUNDARY LAYING SOMEWHERE CLOSE TO OUR AREA ON FRIDAY NIGHT AND
SATURDAY. THE UPPER LEVEL TROUGH SWINGS THROUGH THE REGION ON
SUNDAY...KEEPING A CHANCE OF CONVECTION...WITH COOLER AIR BEGINNING
TO PULL IN BEHIND THE SYSTEM.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 108 PM CDT MON MAY 13 2013
VFR EXPECTED TO CONTINUE THROUGH 14/18Z EVEN AS COLD FRONT ENTERS
THE NORTHWEST CORNER OF THE AREA INCLUDING HON BY 14/18Z. SURFACE
GUSTS TO 25 TO 30 KNOTS FROM THE WEST TO SOUTHWEST IN SOUTHWEST MN
AND NORTHWEST IA WILL DECREASE BY 23Z BUT MAY REDEVELOP AFTER
14/15Z OVER THE AREA. WINDS WILL SHIFT TO THE NORTHWEST OVER THE
NORTHWEST CORNER OF THE AREA INCLUDING HON NEAR END OF PERIOD BY
14/18Z.
&&
.FIRE WEATHER...
ISSUED AT 1023 AM CDT MON MAY 13 2013
FIRE WEATHER WAS DISCUSSED EXTENSIVELY IN BOTH SHORT AND LONG TERM
SECTIONS EARLIER. MAIN PROBLEM WITH WINDS COMING UP A LITTLE
FASTER THAN EXPECTED IN OUR EAST IS A POSSIBLE NEED FOR A RED FLAG
WARNING FOR THIS AFTERNOON IN OUR EAST...EVEN THOUGH DEW POINTS
ARE COMING UP ABOUT AS WE HAD. WILL TRY TO ISSUE BY THE START OF
THE AFTERNOON IF WE DECIDE ONE IS NEEDED. OF COURSE WILL ALSO BE
CHECKING ON A POSSIBLE UPGRADE OF TUESDAY WATCH TO A WARNING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR SDZ255>258.
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR MNZ900.
RED FLAG WARNING UNTIL 6 PM CDT THIS EVENING FOR MNZ900.
IA...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR IAZ300-301.
RED FLAG WARNING UNTIL 6 PM CDT THIS EVENING FOR IAZ301.
NE...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR NEZ249.
&&
$$
UPDATE...
SHORT TERM...MJF/JM
LONG TERM...JM
AVIATION...
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
515 PM CDT MON MAY 13 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 233 PM CDT MON MAY 13 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED OVER THE CENTRAL GREAT LAKES AND A WARM FRONT EXTENDING
SOUTH ACROSS THE GREAT PLAINS. LEADING EDGE OF THE WARM/MOIST AIR
ALOFT IS PRODUCING A NARROW BAND OF LIGHT RAIN ALONG THE WI/MN
BORDER THIS AFTERNOON...WHICH IS MEASURING A HUNDREDTH OR TWO
ACCORDING TO THE OBS. BAND OF LIGHT RAIN ALONG THIS 295-300K
MOISTURE ADVECTION WILL PUSH INTO CENTRAL WISCONSIN AROUND
5PM...DESPITE VERY DRY AIR PRESENTLY AT THE SURFACE. WEST OF THE
WARM FRONT...TEMPERATURES ARE MAINLY IN THE 80S AND A COUPLE 90
DEGREE READINGS ARE OUT THERE AS WELL. THE MAIN FORECAST CONCERNS
ARE TIMING OF THE PRECIP LATER THIS AFTERNOON INTO THIS
EVENING...FOLLOWED BY TEMPS AND SMALL THUNDER CHANCES TOMORROW.
TONIGHT...295-300K MOISTURE ADVECTION WILL PUSH A BAND OF LIGHT RAIN
ACROSS THE AREA LATER THIS AFTERNOON AND THROUGH THE EVENING.
MID-LEVEL LAPSE RATES ARE POOR AND SURFACE HUMIDITIES ARE IN THE
20S...SO SHOWERS SHOULD NOT AMOUNT TO MUCH. BUT OBS UPSTREAM
INDICATE A HUNDREDTH OR TWO OF ACCUM...SO WILL SHOW THIS IN THE
FORECAST AND RAISE POPS INTO THE LIKELY RANGE. THIS BAND WILL EXIT
LATE THIS EVENING...BUT A SECONDARY SURGE OF MOISTURE MAY CAUSE
ADDITIONAL REDEVELOPMENT OF SHOWERS OVER THE EASTERN HALF OR THIRD
OF THE FORECAST AREA AFTER MIDNIGHT. THINK PRECIP CHANCES WILL
LIKELY BE OVER BY THE START OF THE MORNING COMMUTE WHILE SKIES WILL
BE CLEARING FROM WEST TO EAST AT THE SAME TIME. PLENTY OF CLOUDS
AND A LIGHT SE WIND WILL KEEP TEMPS CONSIDERABLY WARMER THAN LAST
NIGHT AND WILL GO WITH LOWS IN THE LOW TO MID 40S.
TUESDAY...ELEVATED WARM FRONT WILL BE SHIFTING ACROSS LAKE MICHIGAN
EARLY TUESDAY MORNING...WHICH WILL RESULT IN CLEARING SKIES ACROSS
EASTERN WISCONSIN EARLY ON. EVEN THOUGH WILL LIKELY SEE CIRRUS
OVERHEAD...MODELS FORECAST VERY DRY AIR ARRIVING IN THE LOW TO MID
LEVELS SO DO NOT SEE A THREAT OF PRECIP THROUGH MID-AFTERNOON. BY
MID TO LATE AFTERNOON...LOW PRESSURE WILL BE ACROSS CENTRAL
MINNESOTA...AND A 850MB LLJ WILL PUSH A WARM FRONT INTO SW
WISCONSIN. ORDINARILY...MASS CONVERGENCE ON THE NOSE OF THE LLJ
WOULD BE CONDUCIVE FOR THUNDERSTORMS...ESPECIALLY WITH MID-LEVEL
LAPSE RATES AROUND 8 C/KM....BUT THE INCOMING AIRMASS IS SO DRY
BELOW 600MB...AND EXPECT SURFACE DEWPOINTS TO FALL THROUGH THE
AFTERNOON. THIS RESULTS IN PROGGED CONVECTIVE INHIBITION OF 200-300
J/KG LATE IN THE AFTERNOON WHEN THE FORCING ARRIVES...WHICH LOOKS
AWFULLY TOUGH TO OVERCOME. WILL LEAVE AN ISOLATED MENTION IN THE
FORECAST OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. STRONG WARM
ADVECTION WILL PUSH TEMPS INTO THE LOWER 80S OVER CENTRAL
WISCONSIN...BUT A NE WIND WILL KEEP TEMPS IN THE 50S AND 60S OVER
FAR NE WISCONSIN.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 233 PM CDT MON MAY 13 2013
MAIN FCST CONCERNS INCLUDE SVR TSTM POTENTIAL TUESDAY EVENING...
A DRY PERIOD FOR THE MIDDLE TO LATE PART OF THE WORK WEEK...THEN
A RETURN TO SHOWERY BUT SEASONABLE PERIOD FOR THE WEEKEND AND
EARLY NEXT WEEK.
NOTHING HAS CHANGED FOR TUESDAY NIGHT...WITH ENOUGH ELEVATED INSTABILITY
(MUCAPES 750-1500 J/KG) AND SHEAR (STG DEEP LAYER SHEAR AND 0-3 KM
HELICITIES OF 500-700) TO SUPPORT ELEVATED SUPERCELL TSTMS...BUT A
DRY AND CAPPED ATMOSPHERE LIKELY SUPPRESSING CONVECTIVE INITIATION.
HAD TO LIFT PARCELS FROM THE 850-750 MB LAYER TO GET CONVECTIVE
INHIBITION UNDER 50 J/KG...AND LOWER LEVEL PARCELS ARE MUCH MORE
STRONGLY CAPPED. BEST BEST FOR CONVECTIVE INITIATION WILL LIKELY BE
ON THE NOSE OF A 40 KT LLJ AS IT MOVES INTO NE WI DURING THE EVENING.
HAVE LOWERED POPS SLIGHTLY FROM THE PREVIOUS FEW FCSTS...BUT CAN`T
RISK A DRY FCST...GIVEN THE SVR WX PARAMETERS THAT ARE IN PLACE. SPC
HAS OUR AREA IN THE DAY 2 SEE TEXT...WHICH SEEMS REASONABLE. ANY
THREAT OF CONVECTION SHOULD END BY 06Z/WED AS THE H8 MOISTURE
CONVERGENCE SHIFTS EAST...AND THE COLD/OCCLUDED FRONT REACHES LAKE
MICHIGAN.
LOOKS LIKE A DRY PERIOD FROM LATE TUESDAY NIGHT THROUGH THURSDAY
NIGHT OR FRIDAY MORNING...AS THE COLD FRONT SAGS WELL SOUTH OF THE
REGION AND WEAK HIGH PRESSURE ARRIVES. DEEP MIXING ON WEDNESDAY AND
THURSDAY SHOULD ALLOW TEMPERATURES TO WARM INTO THE LOWER TO MIDDLE
70S IN MOST PLACES...AND ALSO CAUSE DEW POINTS/RELATIVE HUMIDITIES
TO CRASH DURING THE AFTERNOONS. GIVEN THE DRYNESS OF THE AIR MASS...
HAVE LOWERED MIN TEMPS CONSIDERABLY ON WEDNESDAY NIGHT...ESPECIALLY
IN THE TYPICAL COLD SPOTS IN NC WI.
THE PATTERN WILL UNDERGO A SIGNIFICANT CHANGE FOR THE WEEKEND AND
EARLY NEXT WEEK. AN UPPER LEVEL TROF IS EXPECTED TO DEVELOP OVER
THE ROCKIES ON FRIDAY...THEN TRACK EAST TO THE WESTERN GREAT LAKES
BY SUNDAY/MONDAY. AS THIS OCCURS...LOW PRESSURE WILL DEVELOP OVER
THE HIGH PLAINS...THEN LIFT EAST-NORTHEAST TOWARD THE REGION. THIS
WILL CAUSE THE OLD COLD FRONT TO LIFT BACK TO THE NORTH AS A WARM
FRONT...THEN BECOME STATIONARY ACROSS WI LATE IN THE PERIOD. THIS
WILL SET THE STAGE FOR AN EXTENDED PERIOD OF SHOWERS AND SCT TSTMS...
WITH THE POTENTIAL FOR SIGNIFICANT RAINFALL AMOUNTS. TEMPERATURES
SHOULD REMAIN NEAR SEASONAL NORMALS...WITH HIGHS IN THE 60S TO
AROUND 70.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 451 PM CDT MON MAY 13 2013
A NORTH TO SOUTH BAND OF LIGHT SHOWERS EXTENDING THE ENTIRE
LENGTH OF THE STATE WILL PASS QUICKLY OVER CENTRAL AND NORTHEAST
WISCONSIN THIS EVENING. AN ISOLATED MVFR CIG WILL BE POSSIBLE WITH
A FEW OF THE SHOWERS ALONG THIS BAND...OTHERWISE VFR CONDITIONS TO
DOMINATE THROUGH TUESDAY. INCREASING SOUTHWEST WINDS AT 1000 FEET AGL
AND ABOVE LATER THIS EVENING WILL INCREASE LLWS CONDITIONS BEFORE
SUBSINDING AFTER 15Z TUESDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TDH
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 233 PM CDT MON MAY 13 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED OVER THE CENTRAL GREAT LAKES AND A WARM FRONT EXTENDING
SOUTH ACROSS THE GREAT PLAINS. LEADING EDGE OF THE WARM/MOIST AIR
ALOFT IS PRODUCING A NARROW BAND OF LIGHT RAIN ALONG THE WI/MN
BORDER THIS AFTERNOON...WHICH IS MEASURING A HUNDREDTH OR TWO
ACCORDING TO THE OBS. BAND OF LIGHT RAIN ALONG THIS 295-300K
MOISTURE ADVECTION WILL PUSH INTO CENTRAL WISCONSIN AROUND
5PM...DESPITE VERY DRY AIR PRESENTLY AT THE SURFACE. WEST OF THE
WARM FRONT...TEMPERATURES ARE MAINLY IN THE 80S AND A COUPLE 90
DEGREE READINGS ARE OUT THERE AS WELL. THE MAIN FORECAST CONCERNS
ARE TIMING OF THE PRECIP LATER THIS AFTERNOON INTO THIS
EVENING...FOLLOWED BY TEMPS AND SMALL THUNDER CHANCES TOMORROW.
TONIGHT...295-300K MOISTURE ADVECTION WILL PUSH A BAND OF LIGHT RAIN
ACROSS THE AREA LATER THIS AFTERNOON AND THROUGH THE EVENING.
MID-LEVEL LAPSE RATES ARE POOR AND SURFACE HUMIDITIES ARE IN THE
20S...SO SHOWERS SHOULD NOT AMOUNT TO MUCH. BUT OBS UPSTREAM
INDICATE A HUNDREDTH OR TWO OF ACCUM...SO WILL SHOW THIS IN THE
FORECAST AND RAISE POPS INTO THE LIKELY RANGE. THIS BAND WILL EXIT
LATE THIS EVENING...BUT A SECONDARY SURGE OF MOISTURE MAY CAUSE
ADDITIONAL REDEVELOPMENT OF SHOWERS OVER THE EASTERN HALF OR THIRD
OF THE FORECAST AREA AFTER MIDNIGHT. THINK PRECIP CHANCES WILL
LIKELY BE OVER BY THE START OF THE MORNING COMMUTE WHILE SKIES WILL
BE CLEARING FROM WEST TO EAST AT THE SAME TIME. PLENTY OF CLOUDS
AND A LIGHT SE WIND WILL KEEP TEMPS CONSIDERABLY WARMER THAN LAST
NIGHT AND WILL GO WITH LOWS IN THE LOW TO MID 40S.
TUESDAY...ELEVATED WARM FRONT WILL BE SHIFTING ACROSS LAKE MICHIGAN
EARLY TUESDAY MORNING...WHICH WILL RESULT IN CLEARING SKIES ACROSS
EASTERN WISCONSIN EARLY ON. EVEN THOUGH WILL LIKELY SEE CIRRUS
OVERHEAD...MODELS FORECAST VERY DRY AIR ARRIVING IN THE LOW TO MID
LEVELS SO DO NOT SEE A THREAT OF PRECIP THROUGH MID-AFTERNOON. BY
MID TO LATE AFTERNOON...LOW PRESSURE WILL BE ACROSS CENTRAL
MINNESOTA...AND A 850MB LLJ WILL PUSH A WARM FRONT INTO SW
WISCONSIN. ORDINARILY...MASS CONVERGENCE ON THE NOSE OF THE LLJ
WOULD BE CONDUCIVE FOR THUNDERSTORMS...ESPECIALLY WITH MID-LEVEL
LAPSE RATES AROUND 8 C/KM....BUT THE INCOMING AIRMASS IS SO DRY
BELOW 600MB...AND EXPECT SURFACE DEWPOINTS TO FALL THROUGH THE
AFTERNOON. THIS RESULTS IN PROGGED CONVECTIVE INHIBITION OF 200-300
J/KG LATE IN THE AFTERNOON WHEN THE FORCING ARRIVES...WHICH LOOKS
AWFULLY TOUGH TO OVERCOME. WILL LEAVE AN ISOLATED MENTION IN THE
FORECAST OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. STRONG WARM
ADVECTION WILL PUSH TEMPS INTO THE LOWER 80S OVER CENTRAL
WISCONSIN...BUT A NE WIND WILL KEEP TEMPS IN THE 50S AND 60S OVER
FAR NE WISCONSIN.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 233 PM CDT MON MAY 13 2013
MAIN FCST CONCERNS INCLUDE SVR TSTM POTENTIAL TUESDAY EVENING...
A DRY PERIOD FOR THE MIDDLE TO LATE PART OF THE WORK WEEK...THEN
A RETURN TO SHOWERY BUT SEASONABLE PERIOD FOR THE WEEKEND AND
EARLY NEXT WEEK.
NOTHING HAS CHANGED FOR TUESDAY NIGHT...WITH ENOUGH ELEVATED INSTABILITY
(MUCAPES 750-1500 J/KG) AND SHEAR (STG DEEP LAYER SHEAR AND 0-3 KM
HELICITIES OF 500-700) TO SUPPORT ELEVATED SUPERCELL TSTMS...BUT A
DRY AND CAPPED ATMOSPHERE LIKELY SUPPRESSING CONVECTIVE INITIATION.
HAD TO LIFT PARCELS FROM THE 850-750 MB LAYER TO GET CONVECTIVE
INHIBITION UNDER 50 J/KG...AND LOWER LEVEL PARCELS ARE MUCH MORE
STRONGLY CAPPED. BEST BEST FOR CONVECTIVE INITIATION WILL LIKELY BE
ON THE NOSE OF A 40 KT LLJ AS IT MOVES INTO NE WI DURING THE EVENING.
HAVE LOWERED POPS SLIGHTLY FROM THE PREVIOUS FEW FCSTS...BUT CAN`T
RISK A DRY FCST...GIVEN THE SVR WX PARAMETERS THAT ARE IN PLACE. SPC
HAS OUR AREA IN THE DAY 2 SEE TEXT...WHICH SEEMS REASONABLE. ANY
THREAT OF CONVECTION SHOULD END BY 06Z/WED AS THE H8 MOISTURE
CONVERGENCE SHIFTS EAST...AND THE COLD/OCCLUDED FRONT REACHES LAKE
MICHIGAN.
LOOKS LIKE A DRY PERIOD FROM LATE TUESDAY NIGHT THROUGH THURSDAY
NIGHT OR FRIDAY MORNING...AS THE COLD FRONT SAGS WELL SOUTH OF THE
REGION AND WEAK HIGH PRESSURE ARRIVES. DEEP MIXING ON WEDNESDAY AND
THURSDAY SHOULD ALLOW TEMPERATURES TO WARM INTO THE LOWER TO MIDDLE
70S IN MOST PLACES...AND ALSO CAUSE DEW POINTS/RELATIVE HUMIDITIES
TO CRASH DURING THE AFTERNOONS. GIVEN THE DRYNESS OF THE AIR MASS...
HAVE LOWERED MIN TEMPS CONSIDERABLY ON WEDNESDAY NIGHT...ESPECIALLY
IN THE TYPICAL COLD SPOTS IN NC WI.
THE PATTERN WILL UNDERGO A SIGNIFICANT CHANGE FOR THE WEEKEND AND
EARLY NEXT WEEK. AN UPPER LEVEL TROF IS EXPECTED TO DEVELOP OVER
THE ROCKIES ON FRIDAY...THEN TRACK EAST TO THE WESTERN GREAT LAKES
BY SUNDAY/MONDAY. AS THIS OCCURS...LOW PRESSURE WILL DEVELOP OVER
THE HIGH PLAINS...THEN LIFT EAST-NORTHEAST TOWARD THE REGION. THIS
WILL CAUSE THE OLD COLD FRONT TO LIFT BACK TO THE NORTH AS A WARM
FRONT...THEN BECOME STATIONARY ACROSS WI LATE IN THE PERIOD. THIS
WILL SET THE STAGE FOR AN EXTENDED PERIOD OF SHOWERS AND SCT TSTMS...
WITH THE POTENTIAL FOR SIGNIFICANT RAINFALL AMOUNTS. TEMPERATURES
SHOULD REMAIN NEAR SEASONAL NORMALS...WITH HIGHS IN THE 60S TO
AROUND 70.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1227 PM CDT MON MAY 13 2013
A WARM FRONT OVER THE NORTHERN MISSISSIPPI VALLEY WILL
SHIFT EAST ACROSS WISCONSIN LATE THIS AFTERNOON THROUGH THE
EVENING. IT WILL BRING A COUPLE HOUR PERIOD OF LIGHT RAIN
SHOWERS...BUT CIGS TO REMAIN VFR DUE TO VERY DRY AIR IN THE LOW
LEVELS. CIGS WILL LOWER A BIT AFTER THE RAIN DEPARTS LATE THIS
EVENING BUT LOW LEVEL WIND SHEAR WILL THEN DEVELOP FOR A PERIOD.
CLOUDS TO CLEAR LATE TONIGHT AND INTO THE MORNING WHICH WILL SET UP
VFR CONDITIONS FOR MUCH OF THE DAY TOMORROW.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......MPC