Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/31/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1023 AM MDT THU AUG 30 2012
.UPDATE...RED FLAG WARNING FOR THE EASTERN PLAINS STILL ON
TRACK...ESPECIALLY WITH THE POOR OVERNIGHT HUMIDITY RECOVERIES.
SOME SPOTS IN EASTERN ADAMS AND ARAPAHOE COUNTIES AS WELL AS INTO
WASHINGTON AND LOGAN COUNTIES SAW HUMIDITIES RECOVER ONLY INTO THE
LOW 20 PERCENT RANGE. SOUTHERLY WINDS ARE BEGINNING TO INCREASE
AND MAY CAUSE CRITERIA TO BE REACH A LITTLE BEFORE NOON WHEN THE
WARNING BEGINS.
CONVECTION OVER THE HIGH TERRAIN ALREADY GETTING STARTED. CAPE
VALUES CURRENTLY SHOWN TO BE AROUND 150 TO 200 J/KG BY THE RUC13
MODEL. PRECIPITABLE WATER VALUES ABOUT 0.5-0.1 INCHES LESS THAN
THIS TIME YESTERDAY. STILL EXPECT SOME LIGHT RAIN WITH GUSTY WINDS
FROM THESE STORMS...AND THESE SHOULD MAINLY STAY OVER THE
MOUNTAINS WITH JUST A SLIGHT CHANCE OF THEM MOVING OFF LATER THIS
AFTERNOON OVER THE NORTHERN I25 CORRIDOR.
&&
.AVIATION...NO BIG CHANGES EXPECTED FOR THE 18Z TAF PACKAGE. STILL
EXPECT TSTM ACTIVITY TO STAY OVER THE HIGHER TERRAIN TO THE WEST
OF THE AIRPORTS TODAY...SO WILL KEEP OUT ANY MENTION OF VCTS IN
THE 18Z TAF PACKAGE. SOUTHERLY WINDS BEGINNING TO SHOW IN RADAR
VELOCITY TO THE EAST OF KDEN...EXPECT THESE TO REACH THE AIRPORTS
WITHIN A COUPLE HOURS. SOUTHEASTERLY WINDS THIS AFTERNOON WILL
RETURN TO DRAINAGE THIS EVENING THEN ANOTHER DAY OF SOUTHERLY
WINDS TOMORROW. VFR CONDITIONS FOR THE NEXT 24-36 HOURS UNDER A
MAINLY DRY AIRMASS.
&&
.PREV DISCUSSION... /ISSUED 333 AM MDT THU AUG 30 2012/
SHORT TERM...THE UPPER LEVEL RIDGE WILL WEAKEN SOME TODAY HOWEVER
THAT WILL NOT CHANGE THE OVERALL PTRN MUCH. SOME SUBTROPICAL
MOISTURE WILL CONTINUE TO AFFECT THE MTNS WITH SCT AFTN AND EARLY
EVENING TSTMS WHILE THE FOOTHILLS AND HIGHER VALLEYS SEE WDLY SCT
TSTMS. OVER NERN CO IT WILL REMAIN DRY EXCEPT NR THE FOOTHILLS AND
ALONG THE WY-CO BORDER WHERE A FEW STORMS WILL BE POSSIBLE. HIGHS THIS
AFTN WILL BE SIMILAR TO WED WITH RECORD HIGHS POSSIBLE ONCE AGAIN.
MEANWHILE GUSTY SOUTH WINDS COMBINED WITH LOW HUMIDITY WILL CREATE
HIGH FIRE DANGER OVER MOST OF THE PLAINS.
LONG TERM...NO BIG CHANGES IN FORECAST REASONING THIS TIME
AROUND. THE MAIN IDEA REMAINS THAT THE UPPER RIDGE OVER THE STATE
TODAY WILL FLATTEN AND EXPAND ACROSS THE SOUTHERN HALF OF THE
COUNTRY OVER THE WEEKEND AS TROPICAL STORM ISAAC MOVES UP THE
MISSISSIPPI VALLEY THEN EASTWARD OVER THE OHIO VALLEY. WEAK FLOW
ALOFT OVER COLORADO WILL BECOME MORE WESTERLY OVER TIME. MID-LEVEL
MOISTURE WILL LINGER OVER THE STATE TO FUEL AFTERNOON SHOWERS OVER
THE MOUNTAINS EACH AFTERNOON. AT LOWER LEVELS TEMPERATURES WILL BE
GRADUALLY COOLING THROUGH THE WEEKEND AS THICKNESS VALUES
DECREASE. TEMPERATURES WILL STILL BE WELL ABOVE NORMAL FOR EARLY
SEPTEMBER THOUGH. AS TEMPERATURES SLOWLY MODERATE AND WINDS
DECREASE...THE THREAT OF DANGEROUS FIRE WEATHER CONDITIONS WILL
ALSO DECREASE. NO ADDITIONAL FIRE WEATHER HIGHLIGHTS ARE EXPECTED
AT THIS TIME.
AFTER ABOUT SUNDAY THE GFS AND ECMWF BEGIN SHOWING DIFFERENCES IN
HOW MUCH MOISTURE AND PRECIPITATION WILL OCCUR OVER THE FORECAST
AREA. THE GFS IS THE MOISTER MODEL...DRAWING MOISTURE OVER THE
STATE FROM THE REMAINS OF PACIFIC HURRICANE ILEANA WHICH IS
CURRENTLY SOUTH OF BAJA CALIFORNIA. THE ECMWF HANDLES ILEANA
DIFFERENTLY FROM THE GFS BY TAKING THE HURRICANE ON A MORE
WESTERLY TRACK. THEREFORE THE ECMWF HAS LESS MOISTURE ACROSS THE
SOUTHWESTERN U.S. FROM SUNDAY ONWARDS. A COMPROMISE SOLUTION
BETWEEN THESE TWO MODELS WOULD THEREFORE HAVE A SLIGHT CHANCE OF
SHOWERS CONTINUING OVER OUR MOUNTAINS THROUGH THE FIRST HALF OF
NEXT WEEK. THE IDEA OF AFTERNOON SHOWERS PRIMARILY OVER THE
MOUNTAINS HAS BEEN WORKING WELL FOR US FOR THE MOST OF THE PAST
COUPLE WEEKS. WHY SHOULD WE DEVIATE FROM THAT NOW?
AVIATION...ANY TSTM ACTIVITY SHOULD STAY TO THE WEST OF THE
AIRPORT THIS AFTN INTO THE EARLY EVENING HOURS. MEANWHILE SO FAR
THE RAP AND HRRR KEEP WINDS SLY THIS MORNING AND THEN SSE BY EARLY
AFTN. SOME WIND GUSTS TO 20-25 MPH MAY DEVELOP AFTER 21Z AND LAST
THRU 01Z OR SO. OVERNIGHT WINDS SHOULD REMAIN SLY.
HYDROLOGY...SOME WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE
IN THE BURN AREAS HOWEVER RAINFALL AMOUNTS SHOULD BE BELOW ONE QUARTER
INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 8 PM MDT THIS EVENING FOR
COZ242-244>251.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS DENVER CO
333 AM MDT THU AUG 30 2012
.SHORT TERM...THE UPPER LEVEL RIDGE WILL WEAKEN SOME TODAY HOWEVER
THAT WILL NOT CHANGE THE OVERALL PTRN MUCH. SOME SUPTROPICAL
MOISTURE WILL CONTINUE TO AFFECT THE MTNS WITH SCT AFTN AND EARLY
EVENING TSTMS WHILE THE FOOTHILLS AND HIGHER VALLEYS SEE WDLY SCT
TSTMS. OVER NERN CO IT WILL REMAIN DRY EXCEPT NR THE FOOTHILLS AND
ALONG THE WY-CO BORDER WHERE A FEW STORMS WILL BE POSSIBLE. HIGHS THIS
AFTN WILL BE SIMILAR TO WED WITH RECORD HIGHS POSSIBLE ONCE AGAIN.
MEANWHILE GUSTY SOUTH WINDS COMBINED WITH LOW HUMIDITY WILL CREATE
HIGH FIRE DANGER OVER MOST OF THE PLAINS.
.LONG TERM...NO BIG CHANGES IN FORECAST REASONING THIS TIME
AROUND. THE MAIN IDEA REMAINS THAT THE UPPER RIDGE OVER THE STATE
TODAY WILL FLATTEN AND EXPAND ACROSS THE SOUTHERN HALF OF THE
COUNTRY OVER THE WEEKEND AS TROPICAL STORM ISAAC MOVES UP THE
MISSISSIPPI VALLEY THEN EASTWARD OVER THE OHIO VALLEY. WEAK FLOW
ALOFT OVER COLORADO WILL BECOME MORE WESTERLY OVER TIME. MID-LEVEL
MOISTURE WILL LINGER OVER THE STATE TO FUEL AFTERNOON SHOWERS OVER
THE MOUNTAINS EACH AFTERNOON. AT LOWER LEVELS TEMPERATURES WILL BE
GRADUALLY COOLING THROUGH THE WEEKEND AS THICKNESS VALUES
DECREASE. TEMPERATURES WILL STILL BE WELL ABOVE NORMAL FOR EARLY
SEPTEMBER THOUGH. AS TEMPERATURES SLOWLY MODERATE AND WINDS
DECREASE...THE THREAT OF DANGEROUS FIRE WEATHER CONDITIONS WILL
ALSO DECREASE. NO ADDITIONAL FIRE WEATHER HIGHLIGHTS ARE EXPECTED
AT THIS TIME.
AFTER ABOUT SUNDAY THE GFS AND ECMWF BEGIN SHOWING DIFFERENCES IN
HOW MUCH MOISTURE AND PRECIPITATION WILL OCCUR OVER THE FORECAST
AREA. THE GFS IS THE MOISTER MODEL...DRAWING MOISTURE OVER THE
STATE FROM THE REMAINS OF PACIFIC HURRICANE ILEANA WHICH IS
CURRENTLY SOUTH OF BAJA CALIFORNIA. THE ECMWF HANDLES ILEANA
DIFFERENTLY FROM THE GFS BY TAKING THE HURRICANE ON A MORE
WESTERLY TRACK. THEREFORE THE ECMWF HAS LESS MOISTURE ACROSS THE
SOUTHWESTERN U.S. FROM SUNDAY ONWARDS. A COMPROMISE SOLUTION
BETWEEN THESE TWO MODELS WOULD THEREFORE HAVE A SLIGHT CHANCE OF
SHOWERS CONTINUING OVER OUR MOUNTAINS THROUGH THE FIRST HALF OF
NEXT WEEK. THE IDEA OF AFTERNOON SHOWERS PRIMARILY OVER THE
MOUNTAINS HAS BEEN WORKING WELL FOR US FOR THE MOST OF THE PAST
COUPLE WEEKS. WHY SHOULD WE DEVIATE FROM THAT NOW?
&&
.AVIATION...ANY TSTM ACTIVITY SHOULD STAY TO THE WEST OF THE
AIRPORT THIS AFTN INTO THE EARLY EVENING HOURS. MEANWHILE SO FAR
THE RAP AND HRRR KEEP WINDS SLY THIS MORNING AND THEN SSE BY EARLY
AFTN. SOME WIND GUSTS TO 20-25 MPH MAY DEVELOP AFTER 21Z AND LAST
THRU 01Z OR SO. OVERNIGHT WINDS SHOULD REMAIN SLY.
&&
.HYDROLOGY...SOME WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE
IN THE BURN AREAS HOWEVER RAINFALL AMOUNTS SHOULD BE BELOW ONE QUARTER
INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 8 PM MDT THIS EVENING FOR
COZ242-244>251.
&&
$$
SHORT TERM...RPK
LONG TERM....DANKERS
AVIATION...RJK
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
337 AM EDT FRI AUG 31 2012
.DISCUSSION...
...RIP CURRENT THREAT INCREASING OVER THE HOLIDAY WEEKEND...
TODAY/TONIGHT...
TWO DISTINCT H100-H70 ANTICYCLONIC GYRES...ONE OVER THE CAROLINAS
AND ONE JUST E OF THE NRN BAHAMAS...WILL MERGE OVER THE SERN
SEABOARD TODAY AND GENERATE A DEEP N/NERLY FLOW ACRS THE FL
PENINSULA. NE FLOW REGIMES TYPICALLY ARE QUITE STABLE FOR CENTRAL FL
AS THEY TEND TO PUSH DRY/STABLE CONTINENTAL AIR INTO THE REGION.
THE 00Z SOUNDINGS CONTINUE TO SHOW PLENTIFUL MOISTURE ACRS THE STATE
WITH PWAT VALUES BTWN 1.8"-2.0". HOWEVER...THE KTBW/KMFL/KEYW
SOUNDINGS ALL SHOW THE MOISTURE IS MORE OR LESS EVENLY DISTRIBUTED
THRU THE COLUMN...NOT CONCENTRATED IN THE LOW/MID LVLS IN A MANNER
THAT WOULD SUPPORT PRECIP. LATEST RAP ANALYSIS ALSO SHOWS UPSTREAM
MEAN RH VALUES THRU THE H100-H70 LYR ARE LARGELY AOB 70PCT.
FURTHERMORE...RAP ANALYSIS SHOWS H70 TEMPS ARND 10C...H50 TEMPS
AROUND -5.5C...RESULTING IN MID LVL LAPSE RATES AOB 5.5C/KM.
ALOFT...A THIN BAND OF WEAK H85-H50 VORTICITY IS NOTED OVER THE NECK
OF THE PENINSULA BUT IS EMBEDDED IN VERY WEAK FLOW...WHILE THE
H30-H20 WIND PATTERN IS WEAKLY CONVERGENT. SAT PICS SHOW UPR LVL
CLOUD DECK IS NOT AS ROBUST AS A FEW HRS AGO...BUT ANY UPR LVL
DEBRIS CLOUDS THAT PUSH INTO CENTRAL FL WOULD ONLY FURTHER "DAMPEN"
PRECIP CHANCES.
THE AIRMASS IS CONDITIONALLY UNSTABLE...BUT JUST BARELY. WITH
H100-H70 DRY AIR ADVECTION TAKING PLACE...MID LVL THERMAL RIDGING...
AND WEAK DYNAMIC SUPPORT...STORM COVERAGE TODAY WILL BE PRIMARILY
DEPENDENT ON MESOSCALE BOUNDARY COLLISIONS TO FORCE VERTICAL MOTION.
HOWEVER...WITH A NE FLOW REGIME IN PLACE...MOST OF THESE WILL OCCUR
OVER THE W PENINSULA. WILL MENTION A SLGT CHC OF TSRAS OVER THE
INTERIOR COUNTIES AS THINNING UPR LVL CLOUDS MAY ALLOW A FEW SPOTS
TO REACH THEIR CONVECTIVE TEMPS...BUT EVEN THIS IS GENEROUS GIVEN
THE TORPID NATURE OF THIS AIRMASS. THE DEEPENING ONSHORE FLOW WILL
KEEP MAX TEMPS NEAR AVG (U80S/L90S)...MIN TEMPS ABV AVG (M70S).
HOLIDAY WEEKEND...
RIDGING ALOFT AND NORTHEAST UPPER LEVEL WINDS ARE INDICATED ALONG WITH
DEEP LAYER DRYING SO HAVE GONE WITH A DRY FORECAST...ESPECIALLY
SINCE MOS POPS ARE 10 PERCENT OR LESS. AT THE SURFACE...HIGH
PRESSURE RIDGE TO OUR NORTH WILL PROVIDE AN ONSHORE FLOW. THIS
WILL KEEP COASTAL HIGH TEMPS IN THE UPPER 80S WITH MAINLY LOWER
90S ACROSS THE INTERIOR.
WILL HAVE TO WATCH FOR A SMALL LONG PERIOD SWELL FROM DISTANT
TROPICAL CYCLONE KIRK AFFECTING THE BEACHES AND LEADING TO
DANGEROUS RIP CURRENTS BY SUNDAY. SWELLS FROM LESLIE MAY ARRIVE AS
EARLY AS MON.
TUE-FRI...MID-UPPER LEVEL LOW IS FORECAST TO PUSH SLOWLY WEST
ACROSS THE NORTHERN BAHAMAS THEN LIFT OUT TO THE NORTH AS NORTHERN
STREAM TROUGH DIGS OVER THE EASTERN HALF OF THE COUNTRY. THIS RUN
HAS THE LOW MOVING CLOSER TO THE AREA AND THE SUBSIDENCE OUT AHEAD
OF IT PERSISTING LONGER. MOS POPS ONLY REACH 20 PERCENT ON
TUE...30 PERCENT WED-THU...40 PERCENT FRI AND WILL LARGELY FOLLOW
THESE NUMBERS. AT THE SURFACE...THE FLOW REGIME WILL GRADUALLY
TRANSITION FROM LIGHT ONSHORE TO LIGHT OFFSHORE BY LATE WEEK. VERY
LITTLE CHANCE IN HIGH TEMPS INDICATE.
LONG PERIOD SWELLS FROM DISTANT TROPICAL CYCLONE LESLIE WILL CONTINUE
THE THREAT FROM DANGEROUS RIP CURRENTS THROUGH AT LEAST MID WEEK.
&&
.AVIATION...
THRU 31/12Z...LCL MVFR CIGS/VSBYS IN BR N OF KGIF-KDAB...OTHERWISE
VFR ALL SITES THRU 01/00Z...CIGS AOA FL120.
&&
.MARINE...
TODAY/TONIGHT...BROAD SFC/LOW LVL RIDGE CENTERED OVER THE SE COAST
WILL GENERATE A LIGHT TO GENTLE ERLY BREEZE ACRS THE LCL ATLC. SEAS
AOB 2FT. NO TSTM ACTIVITY ANTICIPATED AS NERLY FLOW ALOFT WILL FOCUS
WHAT FEW STORMS FORM THAT DO FORM OVER W FL.
WEEKEND...HIGH PRESSURE RIDGE TO OUR NORTH WILL PROVIDE A
NORTHEAST TO EAST WIND FLOW. THE GFS SHOWS A WEAK INVERTED TROUGH
TRANSITING THE COASTAL WATERS SAT NIGHT INTO SUN WITH POSSIBLE
10-15 KNOTS FLOW...BUT OTHERWISE SPEEDS SHOULD BE AROUND 10 KNOTS.
THE INVERTED TROUGH MAY BRING A FEW SHOWERS...BUT HAVE NOT
INCLUDED IN THE FORECAST YET. SWELLS FROM DISTANT TROPICAL CYCLONE
KIRK MAY IMPACT THE WATERS BY SUNDAY.
MON-TUE...THE HIGH PRESSURE RIDGE WILL SLOWLY PUSH OFFSHORE WITH
MAINLY EAST WINDS 10 KNOTS OR LESS. SMALL FORERUNNER SWELLS FROM
DISTANT TROPICAL CYCLONE LESLIE WILL ARRIVE LATE MON AND CONTINUE
THROUGH MID WEEK WITH GRADUALLY INCREASING HEIGHTS. NAVIGATION
THROUGH INLETS DURING THE OUTGOING TIDE WILL BECOME HAZARDOUS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 88 74 89 71 / 10 0 10 10
MCO 92 75 92 72 / 20 0 10 10
MLB 89 77 87 75 / 10 0 10 10
VRB 88 76 88 73 / 10 0 10 10
LEE 92 74 93 72 / 20 0 10 10
SFB 93 75 91 72 / 20 0 10 10
ORL 92 75 92 73 / 20 0 10 10
FPR 88 76 88 73 / 10 10 10 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM....LASCODY
AREA FORECAST DISCUSSION...UPDATE FOR AVIATION
NWS PEACHTREE CITY GA
141 AM EDT THU AUG 30 2012
.UPDATE...
/ISSUED AT 1102 AM EDT THU AUG 30 2012/
MORNING SOUNDING SHOWS DEEP TROPICAL MOISTURE IN-PLACE WITH 2.17
PW`S AND A MODERATELY STABLE MOIST ADIABATIC PROFILE. THE HRRR AND
NAM MODELS SHOW WIDESPREAD CONVECTION DEVELOPING ACROSS MUCH OF THE
FORECAST AREA TODAY. AS A RESULT... EXPECTING SCATTERED TO
OCCASIONALLY NUMEROUS SHOWERS TO SPREAD UP FROM THE SW DURING
DAYTIME HEATING... WITH THE HIGHER POPS WARRANTED FROM CARROLLTON TO
ATLANTA DOWN TO MACON AND COLUMBUS AREAS. CLOUDS AND MAINLY SHOWERS
WILL HOLD TEMPS AND INSTABILITIES DOWN TO MODEST LEVELS... SO WILL
SHOW MAINLY SHOWERS TODAY... WITH ONLY AN ISOLATED THUNDER THREAT
THROUGH THE AFTERNOON WHERE THE HIGHER POPS ARE SHOWN. WILL UPDATE
ZONES TO REFLECT THESE NEW EXPECTATIONS. OTHERWISE... THE REST OF
FORECAST LOOKS ON TRACK AT THIS TIME.
&&
.PREV DISCUSSION... /ISSUED 431 AM EDT THU AUG 30 2012/
SHORT TERM /TODAY THROUGH FRIDAY/...
CONCERN THIS FCST IS TIMING OF SHRA THIS MORNING AND LIKELIHOOD OF
TSRA THIS AFTERNOON. MODELS IN PRETTY GOOD AGREEMENT THAT WARM/MOIST
ADVECTION ASSOCIATED WITH H8 SOUTHERLY FLOW EAST OF ISAAC AND
LOW/MID LEVEL DEFORMATION ZONE OVER NORTH GA WILL COMMENCE THIS
MORNING. RECENT HRRR RUNS DO A NICE JOB PORTRAYING STRATIFORM PRECIP
DEVELOPING OVER MIDDLE GA EARLY THIS MORNING AND IS SIMILAR TO
LARGER SCALE MODELS SUCH AS THE NAM...GFS AND SREF. HAVE UPDATED
GRIDS TO SHOW A LITTLE HIGHER POP IN THE MORNING. IN THE AFTERNOON
..SHOULD SEE A BRIEF LULL FOLLOWED BY ADDITIONAL SHRA/TSRA AFTER
2PM. AMOUNT AND INTENSITY OF TSRA DEPENDS ON HOW MUCH INSOLATION WE
CAN GET. GOT A LITTLE MORE TSRA THAN EXPECTED YESTERDAY AND A FEW
CELLS APPROACHED SVR...HOWEVER EXPECT COOLER TEMPS AND MORE CLOUDS
THIS AFTERNOON THAN YESTERDAY RESULTING IN CAPE ONLY AT MOST 1000
J/KG.
PRECIP SHOULD END QUICKLY THIS EVENING AS WAA PATTERN DISSIPATES AND
SOLAR INSOLATION ENDS. NOT AS FAVORABLE A PATTERN FOR PRECIP FRIDAY
BUT STILL HAVE SLT CHC BECOMING CHC SHRA/TSRA IN THE AFTERNOON.
MOISTURE FROM ISAAC WILL BE DIFFICULT TO FULLY CLEAR OUT ANYTIME
SOON. AS UPPER RIDGE BUILDS AROUND THE SOUTHEAST CONUS...TEMPS
SHOULD WARM CONSIDERABLY INTO THE UPPER 80S AND LOWER 90S BUT
ABUNDANT MOISTURE WILL HELP KEEP CLOUDS AND AFTERNOON CONVECTION
GOING.
SNELSON
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS IN GOOD AGREEMENT ON TAKING ISAAC NORTHWEST AND LOOPING IT
BACK ACROSS THE OHIO AND TENNESSEE VALLEYS BY SUNDAY. BEYOND THAT
TIME...NOT SO CLEAR WHERE THE REMNANTS OF ISAAC WIND UP. ECMWF
WANTS TO HOLD THE TROUGH ACROSS TENNESSEE AND ALABAMA AREA...WHILE
THE GFS PUSHES THE REMNANT TROUGH EASTWARD. IN GENERAL THERE SEEMS
TO BE NO CHANGE IN AIR MASS FOR THE CWA THROUGH THE PERIOD. HAVE
CONTINUED WITH MOSTLY CHANCE POPS...REDUCING TO SLIGHT CHANCE BY
THE END OF THE FORECAST WHERE THE GFS HINTED AT SOME POSSIBLE
DRYING. TEMPERATURES DEPEND ON AMOUNT OF CLOUDS AND RAIN...SO HAVE
TWEAKED THEM DOWN A BIT TO MID 80S TO LOW 90S.
41
&&
.AVIATION...
18Z UPDATE...
MVFR CIGS ARE EXPECTED TO PERSIST THROUGH AT LEAST 20-21Z TODAY AS
PATCHY -RA/SPOTTY -SHRA`S CONTINUE TO DEVELOP AND MOVE ACROSS THE
TAF SITES THIS AFTN-EVNG. EXPECT THE GREATER TSRA THREAT TO REMAIN
OVER AL... SO WILL ONLY SHOW -RA/-SHRA THRU 02Z... THEN VCSH THRU
06-07Z TNGT. IFR CIGS SHOULD SETTLE BACK IN OVER THE TAF SITES BY
07-09Z TNGT WITH A SLOW IMPROVEMENT TO MVFR BY 15-16Z...THEN VFR BY
19-20Z FRI. THINKING ONLY LOW SCATTERED CONVECTIVE CONVERGE ON
FRI... SO WILL ONLY SHOW VCSH BEGINNING AT 16Z FRI FOR NOW. WINDS
WILL FROM THE SSE AROUND 10KTS THIS AFTN... DIMINISHING TO AROUND
4-6KTS AND BECOMING MORE ESE THIS EVENING...THEN SE AROUND 8-10KTS
ON FRI.
//ATL CONFIDENCE...18Z UPDATE...
MODERATE CONFIDENCE ON TIMING/LOCATION OF SHRA THIS AFTN-EVNG.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 70 88 70 / 50 20 30 20
ATLANTA 83 71 85 73 / 60 40 30 20
BLAIRSVILLE 81 66 82 67 / 40 20 40 20
CARTERSVILLE 85 71 85 70 / 50 30 30 20
COLUMBUS 87 73 89 73 / 60 30 30 20
GAINESVILLE 84 71 86 71 / 50 20 30 20
MACON 86 72 89 72 / 60 40 30 20
ROME 87 71 88 70 / 50 30 40 20
PEACHTREE CITY 84 71 86 70 / 60 40 40 20
VIDALIA 88 73 89 73 / 40 40 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....41
AVIATION...SNELSON
AREA FORECAST DISCUSSION...UPDATE
NWS PEACHTREE CITY GA
1102 AM EDT THU AUG 30 2012
.UPDATE...
MORNING SOUNDING SHOWS DEEP TROPICAL MOISTURE IN-PLACE WITH 2.17
PW`S AND A MODERATELY STABLE MOIST ADIABATIC PROFILE. THE HRRR AND
NAM MODELS SHOW WIDESPREAD CONVECTION DEVELOPING ACROSS MUCH OF THE
FORECAST AREA TODAY. AS A RESULT... EXPECTING SCATTERED TO
OCCASIONALLY NUMEROUS SHOWERS TO SPREAD UP FROM THE SW DURING
DAYTIME HEATING... WITH THE HIGHER POPS WARRANTED FROM CARROLLTON TO
ATLANTA DOWN TO MACON AND COLUMBUS AREAS. CLOUDS AND MAINLY SHOWERS
WILL HOLD TEMPS AND INSTABILITIES DOWN TO MODEST LEVELS... SO WILL
SHOW MAINLY SHOWERS TODAY... WITH ONLY AN ISOLATED THUNDER THREAT
THROUGH THE AFTERNOON WHERE THE HIGHER POPS ARE SHOWN. WILL UPDATE
ZONES TO REFLECT THESE NEW EXPECTATIONS. OTHERWISE... THE REST OF
FORECAST LOOKS ON TRACK AT THIS TIME.
&&
.PREV DISCUSSION... /ISSUED 431 AM EDT THU AUG 30 2012/
SHORT TERM /TODAY THROUGH FRIDAY/...
CONCERN THIS FCST IS TIMING OF SHRA THIS MORNING AND LIKELIHOOD OF
TSRA THIS AFTERNOON. MODELS IN PRETTY GOOD AGREEMENT THAT WARM/MOIST
ADVECTION ASSOCIATED WITH H8 SOUTHERLY FLOW EAST OF ISAAC AND
LOW/MID LEVEL DEFORMATION ZONE OVER NORTH GA WILL COMMENCE THIS
MORNING. RECENT HRRR RUNS DO A NICE JOB PORTRAYING STRATIFORM PRECIP
DEVELOPING OVER MIDDLE GA EARLY THIS MORNING AND IS SIMILAR TO
LARGER SCALE MODELS SUCH AS THE NAM...GFS AND SREF. HAVE UPDATED
GRIDS TO SHOW A LITTLE HIGHER POP IN THE MORNING. IN THE AFTERNOON
..SHOULD SEE A BRIEF LULL FOLLOWED BY ADDITIONAL SHRA/TSRA AFTER
2PM. AMOUNT AND INTENSITY OF TSRA DEPENDS ON HOW MUCH INSOLATION WE
CAN GET. GOT A LITTLE MORE TSRA THAN EXPECTED YESTERDAY AND A FEW
CELLS APPROACHED SVR...HOWEVER EXPECT COOLER TEMPS AND MORE CLOUDS
THIS AFTERNOON THAN YESTERDAY RESULTING IN CAPE ONLY AT MOST 1000
J/KG.
PRECIP SHOULD END QUICKLY THIS EVENING AS WAA PATTERN DISSIPATES AND
SOLAR INSOLATION ENDS. NOT AS FAVORABLE A PATTERN FOR PRECIP FRIDAY
BUT STILL HAVE SLT CHC BECOMING CHC SHRA/TSRA IN THE AFTERNOON.
MOISTURE FROM ISAAC WILL BE DIFFICULT TO FULLY CLEAR OUT ANYTIME
SOON. AS UPPER RIDGE BUILDS AROUND THE SOUTHEAST CONUS...TEMPS
SHOULD WARM CONSIDERABLY INTO THE UPPER 80S AND LOWER 90S BUT
ABUNDANT MOISTURE WILL HELP KEEP CLOUDS AND AFTERNOON CONVECTION
GOING.
SNELSON
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS IN GOOD AGREEMENT ON TAKING ISAAC NORTHWEST AND LOOPING IT
BACK ACROSS THE OHIO AND TENNESSEE VALLEYS BY SUNDAY. BEYOND THAT
TIME...NOT SO CLEAR WHERE THE REMNANTS OF ISAAC WIND UP. ECMWF
WANTS TO HOLD THE TROUGH ACROSS TENNESSEE AND ALABAMA AREA...WHILE
THE GFS PUSHES THE REMNANT TROUGH EASTWARD. IN GENERAL THERE SEEMS
TO BE NO CHANGE IN AIR MASS FOR THE CWA THROUGH THE PERIOD. HAVE
CONTINUED WITH MOSTLY CHANCE POPS...REDUCING TO SLIGHT CHANCE BY
THE END OF THE FORECAST WHERE THE GFS HINTED AT SOME POSSIBLE
DRYING. TEMPERATURES DEPEND ON AMOUNT OF CLOUDS AND RAIN...SO HAVE
TWEAKED THEM DOWN A BIT TO MID 80S TO LOW 90S.
41
&&
.AVIATION...
12Z UPDATE...
IFR CIGS AT MOST LOCATIONS WILL LIFT TO MVFR AROUND 14Z. HAVE
REMOVED RA THIS MORNING IN FAVOR OF VCSH AFTER 16Z AND PREVAILING
SHRA 19Z-00Z. ALSO DROPPED TSRA IN FCST DUE TO INSUFFICIENT
PROBABILITY THIS AFTERNOON. IF WE SEE MORE BREAKS IN THE CLOUDS
TODAY THAN EXPECTED...WILL HAVE TO UPDATE THIS. EAST SFC WINDS
THROUGH AT LEAST 12Z FRI.
//ATL CONFIDENCE...12Z UPDATE...
MODERATE CONFIDENCE ON TSRA LIKELIHOOD AND TIMING/LIKELIHOOD OF
SHRA TODAY.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 70 88 70 / 50 20 30 20
ATLANTA 83 71 85 73 / 60 40 30 20
BLAIRSVILLE 81 66 82 67 / 40 20 40 20
CARTERSVILLE 85 71 85 70 / 50 30 30 20
COLUMBUS 87 73 89 73 / 60 30 30 20
GAINESVILLE 84 71 86 71 / 50 20 30 20
MACON 86 72 89 72 / 60 40 30 20
ROME 87 71 88 70 / 50 30 40 20
PEACHTREE CITY 84 71 86 70 / 60 40 40 20
VIDALIA 88 73 89 73 / 40 40 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....41
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
742 AM EDT THU AUG 30 2012
.UPDATE...
QUICK UPDATE TO DECREASE POPS FOR THE MORNING HOURS. 06Z MODEL
RUNS HINTING AT LACK OF LIFT UNTIL AFTER 15Z WHEN NEARLY ALL
MODELS INDICATING DECENT QPF /0.10-0.25 INCH/ BY 18Z IN NORTH GA.
ALSO DROPPED TSRA PROBS TO CHC WITH 50-70 POPS FOR SHRA THIS
AFTERNOON. REST OF FCST LOOKS GOOD.
SNELSON
&&
.PREV DISCUSSION... /ISSUED 431 AM EDT THU AUG 30 2012/
SHORT TERM /TODAY THROUGH FRIDAY/...
CONCERN THIS FCST IS TIMING OF SHRA THIS MORNING AND LIKELIHOOD OF
TSRA THIS AFTERNOON. MODELS IN PRETTY GOOD AGREEMENT THAT WARM/MOIST
ADVECTION ASSOCIATED WITH H8 SOUTHERLY FLOW EAST OF ISAAC AND
LOW/MID LEVEL DEFORMATION ZONE OVER NORTH GA WILL COMMENCE THIS
MORNING. RECENT HRRR RUNS DO A NICE JOB PORTRAYING STRATIFORM PRECIP
DEVELOPING OVER MIDDLE GA EARLY THIS MORNING AND IS SIMILAR TO
LARGER SCALE MODELS SUCH AS THE NAM...GFS AND SREF. HAVE UPDATED
GRIDS TO SHOW A LITTLE HIGHER POP IN THE MORNING. IN THE AFTERNOON
..SHOULD SEE A BRIEF LULL FOLLOWED BY ADDITIONAL SHRA/TSRA AFTER
2PM. AMOUNT AND INTENSITY OF TSRA DEPENDS ON HOW MUCH INSOLATION WE
CAN GET. GOT A LITTLE MORE TSRA THAN EXPECTED YESTERDAY AND A FEW
CELLS APPROACHED SVR...HOWEVER EXPECT COOLER TEMPS AND MORE CLOUDS
THIS AFTERNOON THAN YESTERDAY RESULTING IN CAPE ONLY AT MOST 1000
J/KG.
PRECIP SHOULD END QUICKLY THIS EVENING AS WAA PATTERN DISSIPATES AND
SOLAR INSOLATION ENDS. NOT AS FAVORABLE A PATTERN FOR PRECIP FRIDAY
BUT STILL HAVE SLT CHC BECOMING CHC SHRA/TSRA IN THE AFTERNOON.
MOISTURE FROM ISAAC WILL BE DIFFICULT TO FULLY CLEAR OUT ANYTIME
SOON. AS UPPER RIDGE BUILDS AROUND THE SOUTHEAST CONUS...TEMPS
SHOULD WARM CONSIDERABLY INTO THE UPPER 80S AND LOWER 90S BUT
ABUNDANT MOISTURE WILL HELP KEEP CLOUDS AND AFTERNOON CONVECTION
GOING.
SNELSON
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS IN GOOD AGREEMENT ON TAKING ISAAC NORTHWEST AND LOOPING IT
BACK ACROSS THE OHIO AND TENNESSEE VALLEYS BY SUNDAY. BEYOND THAT
TIME...NOT SO CLEAR WHERE THE REMNANTS OF ISAAC WIND UP. ECMWF
WANTS TO HOLD THE TROUGH ACROSS TENNESSEE AND ALABAMA AREA...WHILE
THE GFS PUSHES THE REMNANT TROUGH EASTWARD. IN GENERAL THERE SEEMS
TO BE NO CHANGE IN AIR MASS FOR THE CWA THROUGH THE PERIOD. HAVE
CONTINUED WITH MOSTLY CHANCE POPS...REDUCING TO SLIGHT CHANCE BY
THE END OF THE FORECAST WHERE THE GFS HINTED AT SOME POSSIBLE
DRYING. TEMPERATURES DEPEND ON AMOUNT OF CLOUDS AND RAIN...SO HAVE
TWEAKED THEM DOWN A BIT TO MID 80S TO LOW 90S.
41
&&
.AVIATION...
12Z UPDATE...
IFR CIGS AT MOST LOCATIONS WILL LIFT TO MVFR AROUND 14Z. HAVE
REMOVED RA THIS MORNING IN FAVOR OF VCSH AFTER 16Z AND PREVAILING
SHRA 19Z-00Z. ALSO DROPPED TSRA IN FCST DUE TO INSUFFICIENT
PROBABILITY THIS AFTERNOON. IF WE SEE MORE BREAKS IN THE CLOUDS
TODAY THAN EXPECTED...WILL HAVE TO UPDATE THIS. EAST SFC WINDS
THROUGH AT LEAST 12Z FRI.
//ATL CONFIDENCE...12Z UPDATE...
MODERATE CONFIDENCE ON TSRA LIKELIHOOD AND TIMING/LIKELIHOOD OF
SHRA TODAY.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 70 88 70 / 50 20 30 20
ATLANTA 83 71 85 73 / 60 40 30 20
BLAIRSVILLE 81 66 82 67 / 40 20 40 20
CARTERSVILLE 85 71 85 70 / 50 30 30 20
COLUMBUS 87 73 89 73 / 60 30 30 20
GAINESVILLE 84 71 86 71 / 50 20 30 20
MACON 86 72 89 72 / 60 40 30 20
ROME 87 71 88 70 / 50 30 40 20
PEACHTREE CITY 84 71 86 70 / 60 40 40 20
VIDALIA 88 73 89 73 / 40 40 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....41
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
431 AM EDT THU AUG 30 2012
.SHORT TERM /TODAY THROUGH FRIDAY/...
CONCERN THIS FCST IS TIMING OF SHRA THIS MORNING AND LIKELIHOOD OF
TSRA THIS AFTERNOON. MODELS IN PRETTY GOOD AGREEMENT THAT WARM/MOIST
ADVECTION ASSOCIATED WITH H8 SOUTHERLY FLOW EAST OF ISAAC AND
LOW/MID LEVEL DEFORMATION ZONE OVER NORTH GA WILL COMMENCE THIS
MORNING. RECENT HRRR RUNS DO A NICE JOB PORTRAYING STRATIFORM PRECIP
DEVELOPING OVER MIDDLE GA EARLY THIS MORNING AND IS SIMILAR TO
LARGER SCALE MODELS SUCH AS THE NAM...GFS AND SREF. HAVE UPDATED
GRIDS TO SHOW A LITTLE HIGHER POP IN THE MORNING. IN THE AFTERNOON
...SHOULD SEE A BRIEF LULL FOLLOWED BY ADDITIONAL SHRA/TSRA AFTER
2PM. AMOUNT AND INTENSITY OF TSRA DEPENDS ON HOW MUCH INSOLATION WE
CAN GET. GOT A LITTLE MORE TSRA THAN EXPECTED YESTERDAY AND A FEW
CELLS APPROACHED SVR...HOWEVER EXPECT COOLER TEMPS AND MORE CLOUDS
THIS AFTERNOON THAN YESTERDAY RESULTING IN CAPE ONLY AT MOST 1000
J/KG.
PRECIP SHOULD END QUICKLY THIS EVENING AS WAA PATTERN DISSIPATES AND
SOLAR INSOLATION ENDS. NOT AS FAVORABLE A PATTERN FOR PRECIP FRIDAY
BUT STILL HAVE SLT CHC BECOMING CHC SHRA/TSRA IN THE AFTERNOON.
MOISTURE FROM ISAAC WILL BE DIFFICULT TO FULLY CLEAR OUT ANYTIME
SOON. AS UPPER RIDGE BUILDS AROUND THE SOUTHEAST CONUS...TEMPS
SHOULD WARM CONSIDERABLY INTO THE UPPER 80S AND LOWER 90S BUT
ABUNDANT MOISTURE WILL HELP KEEP CLOUDS AND AFTERNOON CONVECTION
GOING.
SNELSON
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS IN GOOD AGREEMENT ON TAKING ISAAC NORTHWEST AND LOOPING IT
BACK ACROSS THE OHIO AND TENNESSEE VALLEYS BY SUNDAY. BEYOND THAT
TIME...NOT SO CLEAR WHERE THE REMNANTS OF ISAAC WIND UP. ECMWF
WANTS TO HOLD THE TROUGH ACROSS TENNESSEE AND ALABAMA AREA...WHILE
THE GFS PUSHES THE REMNANT TROUGH EASTWARD. IN GENERAL THERE SEEMS
TO BE NO CHANGE IN AIR MASS FOR THE CWA THROUGH THE PERIOD. HAVE
CONTINUED WITH MOSTLY CHANCE POPS...REDUCING TO SLIGHT CHANCE BY
THE END OF THE FORECAST WHERE THE GFS HINTED AT SOME POSSIBLE
DRYING. TEMPERATURES DEPEND ON AMOUNT OF CLOUDS AND RAIN...SO HAVE
TWEAKED THEM DOWN A BIT TO MID 80S TO LOW 90S.
41
&&
AVIATION...
06Z UPDATE...
PRIMARY CONCERN IS IFR CIGS THIS MORNING AND SHRA/TSRA THIS
AFTERNOON. DEWPOINT DEPRESSIONS PRETTY LOW IFR CIGS HAVE FORMED
ALREADY IN SEVERAL LOCATIONS INCLUDING KATL. HAVE CONTINUED THIS
IN FCST THRU 14Z. SHRA LIKELY THIS AFTERNOON DUE TO RICH MOISTURE
AND UPWARD MOTION. TSRA NOT AS LIKELY AS YESTERDAY DUE TO LESS
INSTABILITY. HAVE CONTINUED PROB30 FOR TSRA 19Z-00Z BUT MAY REMOVE
THIS IN LATER UPDATES IF DATA CONTINUES TO SHOW LIMITED POTENTIAL
FOR TSRA. EAST SFC WINDS THROUGH THE FORECAST TO CONTINUE.
//ATL CONFIDENCE...06Z UPDATE...
MODERATE CONFIDENCE ON TSRA LIKELIHOOD.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 70 88 70 / 60 20 30 20
ATLANTA 83 71 85 73 / 60 40 30 20
BLAIRSVILLE 81 66 82 67 / 40 20 40 20
CARTERSVILLE 85 71 85 70 / 60 40 30 20
COLUMBUS 87 73 89 73 / 60 30 30 20
GAINESVILLE 84 71 86 71 / 60 20 30 20
MACON 86 72 89 72 / 60 40 30 20
ROME 87 71 88 70 / 60 30 40 20
PEACHTREE CITY 84 71 86 70 / 60 40 40 20
VIDALIA 88 73 89 73 / 40 50 30 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....41
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
513 PM CDT FRI AUG 31 2012
.DISCUSSION...
349 PM CDT
MAIN FORECAST CONCERNS THIS FORECAST PERIOD REVOLVE AROUND PRECIP
CHANCES AND TRENDS...POSSIBLE HEAVY AT TIMES...THIS WEEKEND INTO
THE START OF NEXT WEEK AS REMNANTS OF TROPICAL STORM ISAAC WORK
ITS WAY NORTH ACROSS THE REGION.
IN THE NEAR TERM...LATEST SATELLITE IMAGERY DEPICTING EXPANSIVE
AREA OF MID AND HIGH LEVEL CLOUD COVER CONTINUING TO SPREAD
NORTHWARD ACROSS MUCH OF THE REGION AS THIS SYSTEM SLOWLY MOVES
NORTH. DESPITE AN INCREASE IN CLOUD COVER TODAY...MOSTLY SUNNY TO
PARTLY CLOUDY SKIES HAVE BEEN OBSERVED WITH TEMPERATURES RISING TO
THE LOWER 90S ACROSS NORTHERN ILLINOIS AND MID TO UPPER 80S ACROSS
AREAS SOUTH OF INTERSTATE 80. DESPITE LATEST RADAR IMAGERY SHOWING
SOME WEAK RETURNS FROM THE OUTER BANDS OF THIS SYSTEM ACROSS AREAS
FROM PONTIAC IN ILLINOIS EAST TO FOWLER IN INDIANA...MOST OF THIS
IS NOT REACHING THE GROUND. SOME DRIER AIR IS HELPING WITH THIS
BUT WITH A VERY MOIST AIRMASS ON ITS WAY...IT SHOULDNT TAKE MUCH
LONGER THIS EVENING BEFORE IT STARTS REACHING THE GROUND. OUTSIDE
OF THIS SYSTEM TO THE SOUTH...A COLD FRONT HAS BEEN DROPPING SOUTH
THROUGH PORTIONS OF WISCONSIN TODAY. ALTHOUGH...EXPECT THIS FRONT
TO LOSE ITS SOUTHWARD MOMENTUM THIS EVENING AND THEN BECOME MORE
DIFFUSE AS THE SYSTEM TO THE SOUTH MOVES INTO THE AREA. DESPITE
THIS FRONT ACROSS THE REGION...ANY VERTICAL DEVELOPMENT HAS BEEN
LIMITED AND IS EXPECTED TO REMAIN THIS WAY AS A MORE SUBSIDENT
LARGE SCALE ENVIRONMENT REMAINS OVER THIS BOUNDARY.
SHIFTING TOWARD MAIN FOCUS OF THIS FORECAST PERIOD...REMNANTS OF
TROPICAL STORM ISAAC CONTINUE TO SLOWLY SHIFT NORTH THROUGH
MISSOURI THIS AFTERNOON. THIS SYSTEM IS MARKED WITH A VERY MOIST
ENVIRONMENT...OR A TROPICAL ENVIRONMENT. COPIOUS AMOUNTS OF
MOISTURE WITH 12Z SOUNDINGS ACROSS MISSOURI INDICATING PWATS
AROUND 2.4 INCHES THIS MORNING...AND LATEST RUC ANALYSIS SHOWING
THIS AXIS OF HIGHER PWATS EXTENDING FROM THE ST. LOUIS AREA BACK
SOUTH THROUGH MISSOURI INTO ARKANSAS. WITH A SLOW MOVEMENT OF THIS
SYSTEM TONIGHT...THIS AXIS OF HIGHEST MOISTURE WILL ALSO SHIFT
SLOWLY. NONETHELESS...THESE OUTWARD BANDS OF THIS SYSTEM AND
HIGHER MOISTURE CONTENT AIR WILL LIFT NORTH OVERNIGHT. THIS SHOULD
HELP BRING SHOWERS ACROSS THE SOUTHERN CWA PRIMARILY FOR AREAS
ALONG AND SOUTH OF A LINE FROM PONTIAC IN ILLINOIS TO RENSSELAER
IN INDIANA. HEAVIER DOWNPOURS ARE NOT EXPECTED TONIGHT AS WELL AS
ANY THUNDER. DESPITE SOME INSTABILITY IN PLACE...THESE INITIAL
SHOWERS WILL BE WEAKLY FORCED. ITS NOT UNTIL SATURDAY THROUGH THE
REMAINDER OF THE WEEKEND THAT THE MAIN AXIS OF HIGHEST MOISTURE
AND RAINFALL WILL REACH THE CWA. WITH BETTER FORCING WITH THIS
SYSTEM SHIFTING NORTH AND SREF GUIDANCE INDICATING THAT THE AXIS
OF HIGHER PWATS/MUCH HIGHER DEWPOINT AIR WILL REACH THE SOUTHERN
CWA...THE POTENTIAL FOR HEAVIER RAIN WILL INCREASE. DESPITE SOME
MODEL VARIABILITY WITH THE OVERALL EVOLUTION OF THIS
SYSTEM...CONFIDENCE IS HIGH FOR AREAS ALONG AND SOUTH OF
INTERSTATE 80 TO RECEIVE THE HIGHEST AMOUNTS OF RAIN THIS WEEKEND.
WHERE CONFIDENCE IS LOWER AT THIS TIME IS IN REGARDS TO HOW FAR
NORTH THIS RAIN WILL WORK ITS WAY NORTH. AS A FAIRLY TIGHT
GRADIENT IS EXPECTED WITH THIS PRECIP SHIELD THIS WEEKEND...HAVE
TRIED TO CONVEY THIS AS BEST AS POSSIBLE IN THE GRIDS. IF THIS
SYSTEM WERE TO SHIFT NORTHWARD THAN PREVIOUSLY THOUGHT...THEN THIS
AXIS OF RAINFALL WOULD OF COURSE SHIFT NORTH ACROSS THE CWA. AT
THIS POINT IT APPEARS THAT A DRASTIC CUTOFF IN PRECIP SHOULD OCCUR
AROUND THE I88 CORRIDOR. IN ALL AREAS ACROSS OUR CWA ARE EXPECTED
TO RECEIVE A LARGE AMOUNT OF RAINFALL THROUGH SUNDAY NIGHT...WITH
THE POTENTIAL FOR AMOUNTS OF 4 TO 5 INCHES OR GREATER ALONG AND
SOUTH OF A LINE FROM THE PONTIAC AREA TO THE RENSSELAER AREA.
MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED TO TAPER
FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF THE
INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE 88
CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP TO
ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH. NO
HEADLINES AT THIS TIME BUT WILL CONTINUE THE ESF TODAY.
RODRIGUEZ
&&
.HYDROLOGY...
427 PM CDT
EXPECTED RAINFALL AND POTENTIAL FOR HEAVY RAINFALL...POTENTIALLY
FOR PERIODS OF TIME...ACROSS PORTIONS OF THE CWA STILL ON TRACK
LATE TONIGHT THROUGH THE END OF THE WEEKEND. LATEST OBSERVATIONAL
DATA STILL INDICATING A GOOD SWATH OF MOISTURE JUST SOUTH OF THE
CWA THIS AFTERNOON...WITH LATEST GUIDANCE INDICATING THIS HIGHER
MOISTURE CONTENT AIR TO CONTINUE SPREADING NORTHWARD TONIGHT INTO
SATURDAY. AS THIS SLUG OF MOISTURE MOVES ACROSS THE CWA EARLY
SATURDAY...IT WILL THEN LINGERING THROUGH THE REMAINDER OF THE
WEEKEND. ALTHOUGH...LATEST GUIDANCE CONTINUES TO INDICATE THAT THE
HIGHEST RAIN RATES/RAINFALL SHOULD STAY ACROSS THE SOUTHERN CWA
WHICH SEEMS TO BE ON TRACK. THE POTENTIAL FOR RAINFALL AMOUNTS OF
4 TO 5 INCHES OR GREATER ALONG AND SOUTH OF A LINE FROM THE
PONTIAC AREA TO THE RENSSELAER AREA SEEM TO BE ON TRACK FOR THIS
WEEKEND. MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED
TO TAPER FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF
THE INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE
88 CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP
TO ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH.
DESPITE THE EXPECTED HIGHER RAINFALL THIS WEEKEND...ONLY MINOR
RISES IN AREAS RIVERS ARE EXPECTED WITH NO MAJOR PROBLEMS EXPECTED
AT THIS TIME. A WORST CASE SCENARIO AT THIS TIME BASED ON CURRENT
FORECASTS WOULD BE FOR RIVERS THAT RECEIVE THESE HIGHER AMOUNTS TO
RISE TO MINOR OR JUST ABOVE MODERATE STAGES. ALTHOUGH WOULD LIKE
TO REITERATE SOME UNCERTAINTY WITH THIS SYSTEMS OVERALL
EVOLUTION...THAT EXTENDS INTO THE POTENTIAL RISES. WITH THIS IN
MIND...THIS SITUATION NEEDS TO CONTINUE TO BE CLOSELY MONITORED
THIS WEEKEND AS IT WOULD NOT BE OUT OF THE QUESTION FOR LOCALIZED
AREAS OF HIGHER AMOUNTS AND THUS POSSIBLE HIGHER RISES. SOMETHING
ELSE TO KEEP IN MIND THIS WEEKEND IS THE OVERALL SOIL CONDITIONS
ACROSS THE AREA. WITH A DRY/HARD SOIL IN PLACE...IT WOULD NOT TAKE
MUCH TIME FOR HIGH RAINFALL RATES TO QUICKLY TURN INTO RUNOFF.
ONCE AGAIN...HAVE NOT ISSUED ANY FLOOD HEADLINES AT THIS TIME.
ALTHOUGH...CONTINUE TO MONITOR LATEST UPDATES THIS WEEKEND AS THIS
COMPLEX SYSTEM UNFOLDS ACROSS THE REGION.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* TIMING WIND SHIFT FROM SW TO NE AS FRONTAL BOUNDARY SAGS SOUTH
ACROSS THE TERMINALS.
* TIMING ONSET OF RAINFALL SAT.
BEACHLER
//DISCUSSION...UPDATED 18Z...
MODERATE SW-WSW LOW LEVEL FLOW HAS BEEN MIXING DOWN TO THE
SURFACE WITH THE SKC CONDITIONS ALLOWING MAXIMUM HEATING THROUGH
MIDDAY RESULTING IN SOME GUSTS IN THE 15-20KT RANGE THIS MORNING.
OUTER EDGE OF CLOUD SHIELD OF THE T.D. CENTERED OVER SW MO HAVE
SPREAD TO THE WI BORDER BY EARLY AFTERNOON WITH THICKER CIRRUS
STRATUS TO SPREAD ACROSS THE LOCAL AREA DURING THE MID TO LATE
AFTERNOON.
WITH THICKENING HIGH CLOUDS ADDITIONAL INSOLATION WILL BE
DECREASING THIS AFTERNOON...AND AS THE COLD FRONT ACROSS SOUTHERN
WI CONTINUES TO CREEP SOUTHWARD THE SURFACE PRESSURE GRADIENT
SLACKENS DURING THE AFTERNOON. WITH DECREASE IN BOTH SURFACE
HEATING AND IN SURFACE PRESSURE GRADIENT SW-WSW WINDS WILL LOSE
ANY MARGINAL GUSTS AND SETTLE TO SUSTAINED 10-12KT TIL DUSK. THE
COLD FRONT IS SHOWN BY MODELS TO CROSS INTO FAR NORTHERN IL LATE
THIS AFTERNOON AND EARLY THIS EVENING RESULTING IN A WIND SHIFT
TO OUT OF THE NE-E AT 6-10KT.
MODELS OFFERING SIMILAR SOLUTIONS ON LARGE SCALE BUT DIFFERENCES
IN TIMING AND TRACK OF THE LOW OUT OF CENTRAL MO TO TO W CENTRAL
IL SAT AND SAT NIGHT STILL LEAVES QUESTIONS ABOUT HOW FAR N THE
RAIN WILL SPREAD AND HOW SOON IT WILL ARRIVE IN THE LOCAL AREA.
TREND OF MODELS HAS BEEN SLOWER AND A BIT FURTHER S OF PREVIOUS
FORECAST TRACKS. THIS DELAYS ARRIVAL OF ONSET OF RA AND KEEPS
HEAVIER RAIN S OF ORD AND MDW.
LOWER DEW POINT AIR BEHIND THE SLUGGISH COLD FRONT WILL BE
ADVECTED OVER THE LOCAL TERMINALS ON NE-E LOW LEVEL WINDS
BECOMING MODERATE TONIGHT BETWEEN HIGH PRESSURE BUILDING INTO THE
UPPER GREAT LAKES AND THE LOW RIDGE BETWEEN THE MO LOW. SLIGHTLY
MORE SOUTHWARD TRACK OF THE LOW AS IT MOVES INTO CENTRAL IL SUN
AND INFLUX OF LOWER LOW LEVEL POINTS IS EXPECTED TO DELAY AND
SIGNIFICANT THREAT OF SHRA/RA TIL LATER MORNING-EARLY AFTERNOON
ON SAT...THEN PERSISTING THROUGH THE DAY. WITH HEAVER RAIN
OCCURRING TO THE S OF THE TERMINALS AND THE FEED LOW DRIER LOW
LEVEL AIR EXPECT VFR CONDITIONS TO PREVAIL LOCALLY THOUGH MAY BE
AREAS MVFR BY MID-LATE SAT AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN WIND SPEED.
* MEDIUM/HIGH CONFIDENCE IN WIND SHIFT FROM SW TO NE.
* MODERATE CONFIDENCE IN TIMING OF THE COLD FRONT PASSAGE THIS
EVENING AND THE ACCOMPANYING WIND SHIFT.
* HIGH CONFIDENCE IN VFR AND DRY CONDITIONS THROUGH THE NIGHT AND
EARLY SAT MORNING.
* MODERATE CONFIDENCE IN PREVAILING VFR CONTINUING FROM MID SAT
MORNING ON WITH ONLY AREAS/OCCASIONAL MVFR.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...
SUNDAY...CHC OF RA/SHRA. MVFR/IFR POSSIBLE.
MONDAY...SLGT CHC SHRA/TSRA. MVFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC SHRA/TSRA. OTHERWISE VFR.
RATZER
&&
.MARINE...
351 PM CDT
A COLD FRONT IS SLOWLY SINKING SOUTH ALONG LAKE MICHIGAN AND IS
CURRENTLY LOCATED FROM THE WI/IL STATE LINE THROUGH MUSKEGON. THE
FRONT WILL REACH SOUTHERN LAKE MICHIGAN THIS EVENING WITH WINDS
TURNING NORTH TO NORTHEAST AND GUSTING TO AROUND 20 KT. WINDS WILL
DIMINISH TO 10 TO 15 KT BEHIND THE FRONT AND VEER TO THE EAST BY
SATURDAY MORNING OVER THE SOUTHERN HALF OF THE LAKE. WINDS WILL BE
EAST ALONG THE ENTIRE LAKE BY SATURDAY NIGHT. THE PERSISTENT
EASTERLY FLOW WILL RESULT IN LOCALLY HIGHER WAVES ALONG THE SOUTHERN
WI AND IL COAST LINE OF 5 TO 8 FT BY SUNDAY AFTERNOON. WAVES IN THE
IL NEARSHORE ZONES LOOK LIKE THEY WILL STAY JUST BELOW SMALL CRAFT
ADVISORY CRITERIA...THEREFORE WILL REFRAIN FROM ISSUING A SCY NOW.
HOWEVER...THE HIGHER WAVES AND ONSHORE FLOW ALONG THE IL NEARSHORE
ZONES DO POSE AN INCREASED RIP CURRENT RISK. THE RISK ALSO IS
INCREASED BY THE FACT THERE WILL PROBABLY BE AN ABOVE AVERAGE NUMBER
OF SWIMMERS AT THE BEACH THIS HOLIDAY WEEKEND. ISSUED A RIP CURRENT
STATEMENT FOR THE IL SIDE OF THE LAKE SATURDAY MORNING THROUGH
SUNDAY EVENING.
HIGH PRESSURE SPREADS ACROSS THE WESTERN GREAT LAKES TONIGHT.
MEANWHILE LOW PRESSURE THAT WAS FORMALLY HURRICANE ISAAC IS MOVING
NORTHWARD. THE PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL
TIGHTEN OVER SOUTHERN LAKE MICHIGAN. THEREFORE EAST WINDS WILL BE
STRONGER OVER THE SOUTHERN HALF OF THE LAKE. THE LOW WILL ENTER
SOUTH CENTRAL IL LATE SATURDAY AFTERNOON AND THEN TURN EASTWARD
PASSING SOUTH OF LAKE MICHIGAN. HIGH PRESSURE MOVES OVER THE LAKE
MONDAY NIGHT WITH WINDS WEAKENING ACROSS THE LAKE. ANOTHER TROUGH OF
LOW PRESSURE APPROACHES FROM THE WEST MID NEXT WEEK BUT CONFIDENCE
IS LOW ON THE EXACT TIMING OF THIS SYSTEM DUE TO GUIDANCE
INCONSISTENCIES.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
429 PM CDT FRI AUG 31 2012
.DISCUSSION...
349 PM CDT
MAIN FORECAST CONCERNS THIS FORECAST PERIOD REVOLVE AROUND PRECIP
CHANCES AND TRENDS...POSSIBLE HEAVY AT TIMES...THIS WEEKEND INTO
THE START OF NEXT WEEK AS REMNANTS OF TROPICAL STORM ISAAC WORK
ITS WAY NORTH ACROSS THE REGION.
IN THE NEAR TERM...LATEST SATELLITE IMAGERY DEPICTING EXPANSIVE
AREA OF MID AND HIGH LEVEL CLOUD COVER CONTINUING TO SPREAD
NORTHWARD ACROSS MUCH OF THE REGION AS THIS SYSTEM SLOWLY MOVES
NORTH. DESPITE AN INCREASE IN CLOUD COVER TODAY...MOSTLY SUNNY TO
PARTLY CLOUDY SKIES HAVE BEEN OBSERVED WITH TEMPERATURES RISING TO
THE LOWER 90S ACROSS NORTHERN ILLINOIS AND MID TO UPPER 80S ACROSS
AREAS SOUTH OF INTERSTATE 80. DESPITE LATEST RADAR IMAGERY SHOWING
SOME WEAK RETURNS FROM THE OUTER BANDS OF THIS SYSTEM ACROSS AREAS
FROM PONTIAC IN ILLINOIS EAST TO FOWLER IN INDIANA...MOST OF THIS
IS NOT REACHING THE GROUND. SOME DRIER AIR IS HELPING WITH THIS
BUT WITH A VERY MOIST AIRMASS ON ITS WAY...IT SHOULDNT TAKE MUCH
LONGER THIS EVENING BEFORE IT STARTS REACHING THE GROUND. OUTSIDE
OF THIS SYSTEM TO THE SOUTH...A COLD FRONT HAS BEEN DROPPING SOUTH
THROUGH PORTIONS OF WISCONSIN TODAY. ALTHOUGH...EXPECT THIS FRONT
TO LOSE ITS SOUTHWARD MOMENTUM THIS EVENING AND THEN BECOME MORE
DIFFUSE AS THE SYSTEM TO THE SOUTH MOVES INTO THE AREA. DESPITE
THIS FRONT ACROSS THE REGION...ANY VERTICAL DEVELOPMENT HAS BEEN
LIMITED AND IS EXPECTED TO REMAIN THIS WAY AS A MORE SUBSIDENT
LARGE SCALE ENVIRONMENT REMAINS OVER THIS BOUNDARY.
SHIFTING TOWARD MAIN FOCUS OF THIS FORECAST PERIOD...REMNANTS OF
TROPICAL STORM ISAAC CONTINUE TO SLOWLY SHIFT NORTH THROUGH
MISSOURI THIS AFTERNOON. THIS SYSTEM IS MARKED WITH A VERY MOIST
ENVIRONMENT...OR A TROPICAL ENVIRONMENT. COPIOUS AMOUNTS OF
MOISTURE WITH 12Z SOUNDINGS ACROSS MISSOURI INDICATING PWATS
AROUND 2.4 INCHES THIS MORNING...AND LATEST RUC ANALYSIS SHOWING
THIS AXIS OF HIGHER PWATS EXTENDING FROM THE ST. LOUIS AREA BACK
SOUTH THROUGH MISSOURI INTO ARKANSAS. WITH A SLOW MOVEMENT OF THIS
SYSTEM TONIGHT...THIS AXIS OF HIGHEST MOISTURE WILL ALSO SHIFT
SLOWLY. NONETHELESS...THESE OUTWARD BANDS OF THIS SYSTEM AND
HIGHER MOISTURE CONTENT AIR WILL LIFT NORTH OVERNIGHT. THIS SHOULD
HELP BRING SHOWERS ACROSS THE SOUTHERN CWA PRIMARILY FOR AREAS
ALONG AND SOUTH OF A LINE FROM PONTIAC IN ILLINOIS TO RENSSELAER
IN INDIANA. HEAVIER DOWNPOURS ARE NOT EXPECTED TONIGHT AS WELL AS
ANY THUNDER. DESPITE SOME INSTABILITY IN PLACE...THESE INITIAL
SHOWERS WILL BE WEAKLY FORCED. ITS NOT UNTIL SATURDAY THROUGH THE
REMAINDER OF THE WEEKEND THAT THE MAIN AXIS OF HIGHEST MOISTURE
AND RAINFALL WILL REACH THE CWA. WITH BETTER FORCING WITH THIS
SYSTEM SHIFTING NORTH AND SREF GUIDANCE INDICATING THAT THE AXIS
OF HIGHER PWATS/MUCH HIGHER DEWPOINT AIR WILL REACH THE SOUTHERN
CWA...THE POTENTIAL FOR HEAVIER RAIN WILL INCREASE. DESPITE SOME
MODEL VARIABILITY WITH THE OVERALL EVOLUTION OF THIS
SYSTEM...CONFIDENCE IS HIGH FOR AREAS ALONG AND SOUTH OF
INTERSTATE 80 TO RECEIVE THE HIGHEST AMOUNTS OF RAIN THIS WEEKEND.
WHERE CONFIDENCE IS LOWER AT THIS TIME IS IN REGARDS TO HOW FAR
NORTH THIS RAIN WILL WORK ITS WAY NORTH. AS A FAIRLY TIGHT
GRADIENT IS EXPECTED WITH THIS PRECIP SHIELD THIS WEEKEND...HAVE
TRIED TO CONVEY THIS AS BEST AS POSSIBLE IN THE GRIDS. IF THIS
SYSTEM WERE TO SHIFT NORTHWARD THAN PREVIOUSLY THOUGHT...THEN THIS
AXIS OF RAINFALL WOULD OF COURSE SHIFT NORTH ACROSS THE CWA. AT
THIS POINT IT APPEARS THAT A DRASTIC CUTOFF IN PRECIP SHOULD OCCUR
AROUND THE I88 CORRIDOR. IN ALL AREAS ACROSS OUR CWA ARE EXPECTED
TO RECEIVE A LARGE AMOUNT OF RAINFALL THROUGH SUNDAY NIGHT...WITH
THE POTENTIAL FOR AMOUNTS OF 4 TO 5 INCHES OR GREATER ALONG AND
SOUTH OF A LINE FROM THE PONTIAC AREA TO THE RENSSELAER AREA.
MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED TO TAPER
FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF THE
INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE 88
CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP TO
ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH. NO
HEADLINES AT THIS TIME BUT WILL CONTINUE THE ESF TODAY.
RODRIGUEZ
&&
.HYDROLOGY...
427 PM CDT
EXPECTED RAINFALL AND POTENTIAL FOR HEAVY RAINFALL...POTENTIALLY
FOR PERIODS OF TIME...ACROSS PORTIONS OF THE CWA STILL ON TRACK
LATE TONIGHT THROUGH THE END OF THE WEEKEND. LATEST OBSERVATIONAL
DATA STILL INDICATING A GOOD SWATH OF MOISTURE JUST SOUTH OF THE
CWA THIS AFTERNOON...WITH LATEST GUIDANCE INDICATING THIS HIGHER
MOISTURE CONTENT AIR TO CONTINUE SPREADING NORTHWARD TONIGHT INTO
SATURDAY. AS THIS SLUG OF MOISTURE MOVES ACROSS THE CWA EARLY
SATURDAY...IT WILL THEN LINGERING THROUGH THE REMAINDER OF THE
WEEKEND. ALTHOUGH...LATEST GUIDANCE CONTINUES TO INDICATE THAT THE
HIGHEST RAIN RATES/RAINFALL SHOULD STAY ACROSS THE SOUTHERN CWA
WHICH SEEMS TO BE ON TRACK. THE POTENTIAL FOR RAINFALL AMOUNTS OF
4 TO 5 INCHES OR GREATER ALONG AND SOUTH OF A LINE FROM THE
PONTIAC AREA TO THE RENSSELAER AREA SEEM TO BE ON TRACK FOR THIS
WEEKEND. MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED
TO TAPER FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF
THE INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE
88 CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP
TO ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH.
DESPITE THE EXPECTED HIGHER RAINFALL THIS WEEKEND...ONLY MINOR
RISES IN AREAS RIVERS ARE EXPECTED WITH NO MAJOR PROBLEMS EXPECTED
AT THIS TIME. A WORST CASE SCENARIO AT THIS TIME BASED ON CURRENT
FORECASTS WOULD BE FOR RIVERS THAT RECEIVE THESE HIGHER AMOUNTS TO
RISE TO MINOR OR JUST ABOVE MODERATE STAGES. ALTHOUGH WOULD LIKE
TO REITERATE SOME UNCERTAINTY WITH THIS SYSTEMS OVERALL
EVOLUTION...THAT EXTENDS INTO THE POTENTIAL RISES. WITH THIS IN
MIND...THIS SITUATION NEEDS TO CONTINUE TO BE CLOSELY MONITORED
THIS WEEKEND AS IT WOULD NOT BE OUT OF THE QUESTION FOR LOCALIZED
AREAS OF HIGHER AMOUNTS AND THUS POSSIBLE HIGHER RISES. SOMETHING
ELSE TO KEEP IN MIND THIS WEEKEND IS THE OVERALL SOIL CONDITIONS
ACROSS THE AREA. WITH A DRY/HARD SOIL IN PLACE...IT WOULD NOT TAKE
MUCH TIME FOR HIGH RAINFALL RATES TO QUICKLY TURN INTO RUNOFF.
ONCE AGAIN...HAVE NOT ISSUED ANY FLOOD HEADLINES AT THIS TIME.
ALTHOUGH...CONTINUE TO MONITOR LATEST UPDATES THIS WEEKEND AS THIS
COMPLEX SYSTEM UNFOLDS ACROSS THE REGION.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* TIMING WIND SHIFT FROM WSW TO NE WITH COLD FRONT SINKING FROM
SE AND FAR SW WI DOWN ACROSS THE LOCAL AREA TOWARD EVENING.
* TIMING ONSET AND NORTHWARD EXTEND OF SHOWERS/RAIN ASSOCIATED
WITH T.D. ISAAC ON SAT.
TRS
//DISCUSSION...UPDATED 18Z...
MODERATE SW-WSW LOW LEVEL FLOW HAS BEEN MIXING DOWN TO THE
SURFACE WITH THE SKC CONDITIONS ALLOWING MAXIMUM HEATING THROUGH
MIDDAY RESULTING IN SOME GUSTS IN THE 15-20KT RANGE THIS MORNING.
OUTER EDGE OF CLOUD SHIELD OF THE T.D. CENTERED OVER SW MO HAVE
SPREAD TO THE WI BORDER BY EARLY AFTERNOON WITH THICKER CIRRUS
STRATUS TO SPREAD ACROSS THE LOCAL AREA DURING THE MID TO LATE
AFTERNOON.
WITH THICKENING HIGH CLOUDS ADDITIONAL INSOLATION WILL BE
DECREASING THIS AFTERNOON...AND AS THE COLD FRONT ACROSS SOUTHERN
WI CONTINUES TO CREEP SOUTHWARD THE SURFACE PRESSURE GRADIENT
SLACKENS DURING THE AFTERNOON. WITH DECREASE IN BOTH SURFACE
HEATING AND IN SURFACE PRESSURE GRADIENT SW-WSW WINDS WILL LOSE
ANY MARGINAL GUSTS AND SETTLE TO SUSTAINED 10-12KT TIL DUSK. THE
COLD FRONT IS SHOWN BY MODELS TO CROSS INTO FAR NORTHERN IL LATE
THIS AFTERNOON AND EARLY THIS EVENING RESULTING IN A WIND SHIFT
TO OUT OF THE NE-E AT 6-10KT.
MODELS OFFERING SIMILAR SOLUTIONS ON LARGE SCALE BUT DIFFERENCES
IN TIMING AND TRACK OF THE LOW OUT OF CENTRAL MO TO TO W CENTRAL
IL SAT AND SAT NIGHT STILL LEAVES QUESTIONS ABOUT HOW FAR N THE
RAIN WILL SPREAD AND HOW SOON IT WILL ARRIVE IN THE LOCAL AREA.
TREND OF MODELS HAS BEEN SLOWER AND A BIT FURTHER S OF PREVIOUS
FORECAST TRACKS. THIS DELAYS ARRIVAL OF ONSET OF RA AND KEEPS
HEAVIER RAIN S OF ORD AND MDW.
LOWER DEW POINT AIR BEHIND THE SLUGGISH COLD FRONT WILL BE
ADVECTED OVER THE LOCAL TERMINALS ON NE-E LOW LEVEL WINDS
BECOMING MODERATE TONIGHT BETWEEN HIGH PRESSURE BUILDING INTO THE
UPPER GREAT LAKES AND THE LOW RIDGE BETWEEN THE MO LOW. SLIGHTLY
MORE SOUTHWARD TRACK OF THE LOW AS IT MOVES INTO CENTRAL IL SUN
AND INFLUX OF LOWER LOW LEVEL POINTS IS EXPECTED TO DELAY AND
SIGNIFICANT THREAT OF SHRA/RA TIL LATER MORNING-EARLY AFTERNOON
ON SAT...THEN PERSISTING THROUGH THE DAY. WITH HEAVER RAIN
OCCURRING TO THE S OF THE TERMINALS AND THE FEED LOW DRIER LOW
LEVEL AIR EXPECT VFR CONDITIONS TO PREVAIL LOCALLY THOUGH MAY BE
AREAS MVFR BY MID-LATE SAT AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* MODERATE CONFIDENCE IN TIMING OF THE COLD FRONT PASSAGE THIS
EVENING AND THE ACCOMPANYING WIND SHIFT.
* HIGH CONFIDENCE IN VFR AND DRY CONDITIONS THROUGH THE NIGHT AND
EARLY SAT MORNING.
* MODERATE CONFIDENCE IN PREVAILING VFR CONTINUING FROM MID SAT
MORNING ON WITH ONLY AREAS/OCCASIONAL MVFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...
SUNDAY...CHC OF RA/SHRA. MVFR/IFR POSSIBLE.
MONDAY...SLGT CHC SHRA/TSRA. MVFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC SHRA/TSRA. OTHERWISE VFR.
RATZER
&&
.MARINE...
351 PM CDT
A COLD FRONT IS SLOWLY SINKING SOUTH ALONG LAKE MICHIGAN AND IS
CURRENTLY LOCATED FROM THE WI/IL STATE LINE THROUGH MUSKEGON. THE
FRONT WILL REACH SOUTHERN LAKE MICHIGAN THIS EVENING WITH WINDS
TURNING NORTH TO NORTHEAST AND GUSTING TO AROUND 20 KT. WINDS WILL
DIMINISH TO 10 TO 15 KT BEHIND THE FRONT AND VEER TO THE EAST BY
SATURDAY MORNING OVER THE SOUTHERN HALF OF THE LAKE. WINDS WILL BE
EAST ALONG THE ENTIRE LAKE BY SATURDAY NIGHT. THE PERSISTENT
EASTERLY FLOW WILL RESULT IN LOCALLY HIGHER WAVES ALONG THE SOUTHERN
WI AND IL COAST LINE OF 5 TO 8 FT BY SUNDAY AFTERNOON. WAVES IN THE
IL NEARSHORE ZONES LOOK LIKE THEY WILL STAY JUST BELOW SMALL CRAFT
ADVISORY CRITERIA...THEREFORE WILL REFRAIN FROM ISSUING A SCY NOW.
HOWEVER...THE HIGHER WAVES AND ONSHORE FLOW ALONG THE IL NEARSHORE
ZONES DO POSE AN INCREASED RIP CURRENT RISK. THE RISK ALSO IS
INCREASED BY THE FACT THERE WILL PROBABLY BE AN ABOVE AVERAGE NUMBER
OF SWIMMERS AT THE BEACH THIS HOLIDAY WEEKEND. ISSUED A RIP CURRENT
STATEMENT FOR THE IL SIDE OF THE LAKE SATURDAY MORNING THROUGH
SUNDAY EVENING.
HIGH PRESSURE SPREADS ACROSS THE WESTERN GREAT LAKES TONIGHT.
MEANWHILE LOW PRESSURE THAT WAS FORMALLY HURRICANE ISAAC IS MOVING
NORTHWARD. THE PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL
TIGHTEN OVER SOUTHERN LAKE MICHIGAN. THEREFORE EAST WINDS WILL BE
STRONGER OVER THE SOUTHERN HALF OF THE LAKE. THE LOW WILL ENTER
SOUTH CENTRAL IL LATE SATURDAY AFTERNOON AND THEN TURN EASTWARD
PASSING SOUTH OF LAKE MICHIGAN. HIGH PRESSURE MOVES OVER THE LAKE
MONDAY NIGHT WITH WINDS WEAKENING ACROSS THE LAKE. ANOTHER TROUGH OF
LOW PRESSURE APPROACHES FROM THE WEST MID NEXT WEEK BUT CONFIDENCE
IS LOW ON THE EXACT TIMING OF THIS SYSTEM DUE TO GUIDANCE
INCONSISTENCIES.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
353 PM CDT FRI AUG 31 2012
.DISCUSSION...
349 PM CDT
MAIN FORECAST CONCERNS THIS FORECAST PERIOD REVOLVE AROUND PRECIP
CHANCES AND TRENDS...POSSIBLE HEAVY AT TIMES...THIS WEEKEND INTO
THE START OF NEXT WEEK AS REMNANTS OF TROPICAL STORM ISAAC WORK
ITS WAY NORTH ACROSS THE REGION.
IN THE NEAR TERM...LATEST SATELLITE IMAGERY DEPICTING EXPANSIVE
AREA OF MID AND HIGH LEVEL CLOUD COVER CONTINUING TO SPREAD
NORTHWARD ACROSS MUCH OF THE REGION AS THIS SYSTEM SLOWLY MOVES
NORTH. DESPITE AN INCREASE IN CLOUD COVER TODAY...MOSTLY SUNNY TO
PARTLY CLOUDY SKIES HAVE BEEN OBSERVED WITH TEMPERATURES RISING TO
THE LOWER 90S ACROSS NORTHERN ILLINOIS AND MID TO UPPER 80S ACROSS
AREAS SOUTH OF INTERSTATE 80. DESPITE LATEST RADAR IMAGERY SHOWING
SOME WEAK RETURNS FROM THE OUTER BANDS OF THIS SYSTEM ACROSS AREAS
FROM PONTIAC IN ILLINOIS EAST TO FOWLER IN INDIANA...MOST OF THIS
IS NOT REACHING THE GROUND. SOME DRIER AIR IS HELPING WITH THIS
BUT WITH A VERY MOIST AIRMASS ON ITS WAY...IT SHOULDNT TAKE MUCH
LONGER THIS EVENING BEFORE IT STARTS REACHING THE GROUND. OUTSIDE
OF THIS SYSTEM TO THE SOUTH...A COLD FRONT HAS BEEN DROPPING SOUTH
THROUGH PORTIONS OF WISCONSIN TODAY. ALTHOUGH...EXPECT THIS FRONT
TO LOSE ITS SOUTHWARD MOMENTUM THIS EVENING AND THEN BECOME MORE
DIFFUSE AS THE SYSTEM TO THE SOUTH MOVES INTO THE AREA. DESPITE
THIS FRONT ACROSS THE REGION...ANY VERTICAL DEVELOPMENT HAS BEEN
LIMITED AND IS EXPECTED TO REMAIN THIS WAY AS A MORE SUBSIDENT
LARGE SCALE ENVIRONMENT REMAINS OVER THIS BOUNDARY.
SHIFTING TOWARD MAIN FOCUS OF THIS FORECAST PERIOD...REMNANTS OF
TROPICAL STORM ISAAC CONTINUE TO SLOWLY SHIFT NORTH THROUGH
MISSOURI THIS AFTERNOON. THIS SYSTEM IS MARKED WITH A VERY MOIST
ENVIRONMENT...OR A TROPICAL ENVIRONMENT. COPIOUS AMOUNTS OF
MOISTURE WITH 12Z SOUNDINGS ACROSS MISSOURI INDICATING PWATS
AROUND 2.4 INCHES THIS MORNING...AND LATEST RUC ANALYSIS SHOWING
THIS AXIS OF HIGHER PWATS EXTENDING FROM THE ST. LOUIS AREA BACK
SOUTH THROUGH MISSOURI INTO ARKANSAS. WITH A SLOW MOVEMENT OF THIS
SYSTEM TONIGHT...THIS AXIS OF HIGHEST MOISTURE WILL ALSO SHIFT
SLOWLY. NONETHELESS...THESE OUTWARD BANDS OF THIS SYSTEM AND
HIGHER MOISTURE CONTENT AIR WILL LIFT NORTH OVERNIGHT. THIS SHOULD
HELP BRING SHOWERS ACROSS THE SOUTHERN CWA PRIMARILY FOR AREAS
ALONG AND SOUTH OF A LINE FROM PONTIAC IN ILLINOIS TO RENSSELAER
IN INDIANA. HEAVIER DOWNPOURS ARE NOT EXPECTED TONIGHT AS WELL AS
ANY THUNDER. DESPITE SOME INSTABILITY IN PLACE...THESE INITIAL
SHOWERS WILL BE WEAKLY FORCED. ITS NOT UNTIL SATURDAY THROUGH THE
REMAINDER OF THE WEEKEND THAT THE MAIN AXIS OF HIGHEST MOISTURE
AND RAINFALL WILL REACH THE CWA. WITH BETTER FORCING WITH THIS
SYSTEM SHIFTING NORTH AND SREF GUIDANCE INDICATING THAT THE AXIS
OF HIGHER PWATS/MUCH HIGHER DEWPOINT AIR WILL REACH THE SOUTHERN
CWA...THE POTENTIAL FOR HEAVIER RAIN WILL INCREASE. DESPITE SOME
MODEL VARIABILITY WITH THE OVERALL EVOLUTION OF THIS
SYSTEM...CONFIDENCE IS HIGH FOR AREAS ALONG AND SOUTH OF
INTERSTATE 80 TO RECEIVE THE HIGHEST AMOUNTS OF RAIN THIS WEEKEND.
WHERE CONFIDENCE IS LOWER AT THIS TIME IS IN REGARDS TO HOW FAR
NORTH THIS RAIN WILL WORK ITS WAY NORTH. AS A FAIRLY TIGHT
GRADIENT IS EXPECTED WITH THIS PRECIP SHIELD THIS WEEKEND...HAVE
TRIED TO CONVEY THIS AS BEST AS POSSIBLE IN THE GRIDS. IF THIS
SYSTEM WERE TO SHIFT NORTHWARD THAN PREVIOUSLY THOUGHT...THEN THIS
AXIS OF RAINFALL WOULD OF COURSE SHIFT NORTH ACROSS THE CWA. AT
THIS POINT IT APPEARS THAT A DRASTIC CUTOFF IN PRECIP SHOULD OCCUR
AROUND THE I88 CORRIDOR. IN ALL AREAS ACROSS OUR CWA ARE EXPECTED
TO RECEIVE A LARGE AMOUNT OF RAINFALL THROUGH SUNDAY NIGHT...WITH
THE POTENTIAL FOR AMOUNTS OF 4 TO 5 INCHES OR GREATER ALONG AND
SOUTH OF A LINE FROM THE PONTIAC AREA TO THE RENSSELAER AREA.
MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED TO TAPER
FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF THE
INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE 88
CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP TO
ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH. NO
HEADLINES AT THIS TIME BUT WILL CONTINUE THE ESF TODAY.
RODRIGUEZ
&&
.HYDROLOGY...
441 AM CDT
NOT MUCH HAS CHANGED WITH THE TRACK OF THE REMNANTS OF TROPICAL
CYCLONE ISAAC. THE SYSTEM IS EXPECTED TO TRACK FROM ITS CURRENT
POSITION ACROSS WEST CENTRAL ARKANSAS...NORTHWARD TO CENTRAL
MISSOURI BY EARLY SATURDAY...AND THEN TRANSITION TO THE EAST ALONG
THE INTERSTATE 70 CORRIDOR THIS WEEKEND. DUE TO THE TROPICAL
NATURE OF THE STORM SYSTEM...A VERY HIGH AMOUNT OF ATMOSPHERIC
MOISTURE WILL ACCOMPANY THE SYSTEM. BECAUSE OF THIS...IT APPEARS
LIKELY THAT PERIODS OF HEAVY RAINFALL WILL OCCUR ACROSS CENTRAL
ILLINOIS AND PORTIONS OF NORTHWESTERN INDIANA ON SATURDAY THROUGH
SUNDAY. THE LATEST FORECAST TOTAL RAINFALL AMOUNTS CALLS FOR
BETWEEN THREE TO SIX INCHES ACROSS THE FAR SOUTHERN COUNTIES OF THE
CWA...LIVINGSTON/FORD/IROQUOIS/BENTON...WITH AMOUNTS DROPPING OFF
RAPIDLY TO THE NORTH. IT IS POSSIBLE THAT LOCATIONS NEAR THE
WISCONSIN BORDER MAY SEE VERY LITTLE RAINFALL.
THE RIVER BASINS MOSTLY LIKELY TO SEE THE GREATEST IMPACT WILL BE
THE KANKAKEE...IROQUOIS AND VERMILION RIVERS AND SMALLER RIVERS
AND CREEKS DRAINING INTO THEM. GIVEN THE SLOW MOVEMENT TO THE
SYSTEM AND THE COPIOUS AMOUNTS OF DEEP LAYER MOISTURE LIKELY TO BE
PRESENT...WIDESPREAD RAINFALL AMOUNTS OF 2 INCHES PER SIX HOUR
PERIOD IS POSSIBLE...AND LOCALLY HIGHER AMOUNTS ARE CERTAINLY NOT
OUT OF THE QUESTION. THIS AREA WILL NEED TO BE UNDER CONSIDERATION
FOR AN AREAL FLOOD WARNING
FOR LOCATIONS NORTH OF THE HEAVY RAINFALL AXIS...NORTHWARD TO THE
I-88 CORRIDOR...1 TO 2 INCHES OF TOTAL RAINFALL IS POSSIBLE AND
THE MORE FLASHY BASINS OF THE SOUTHERN PORTIONS OF THE CHICAGO
METRO AREA COULD SEE FLOODING PROBLEMS AS WELL.
KREIN/KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* TIMING WIND SHIFT FROM WSW TO NE WITH COLD FRONT SINKING FROM
SE AND FAR SW WI DOWN ACROSS THE LOCAL AREA TOWARD EVENING.
* TIMING ONSET AND NORTHWARD EXTEND OF SHOWERS/RAIN ASSOCIATED
WITH T.D. ISAAC ON SAT.
TRS
//DISCUSSION...UPDATED 18Z...
MODERATE SW-WSW LOW LEVEL FLOW HAS BEEN MIXING DOWN TO THE
SURFACE WITH THE SKC CONDITIONS ALLOWING MAXIMUM HEATING THROUGH
MIDDAY RESULTING IN SOME GUSTS IN THE 15-20KT RANGE THIS MORNING.
OUTER EDGE OF CLOUD SHIELD OF THE T.D. CENTERED OVER SW MO HAVE
SPREAD TO THE WI BORDER BY EARLY AFTERNOON WITH THICKER CIRRUS
STRATUS TO SPREAD ACROSS THE LOCAL AREA DURING THE MID TO LATE
AFTERNOON.
WITH THICKENING HIGH CLOUDS ADDITIONAL INSOLATION WILL BE
DECREASING THIS AFTERNOON...AND AS THE COLD FRONT ACROSS SOUTHERN
WI CONTINUES TO CREEP SOUTHWARD THE SURFACE PRESSURE GRADIENT
SLACKENS DURING THE AFTERNOON. WITH DECREASE IN BOTH SURFACE
HEATING AND IN SURFACE PRESSURE GRADIENT SW-WSW WINDS WILL LOSE
ANY MARGINAL GUSTS AND SETTLE TO SUSTAINED 10-12KT TIL DUSK. THE
COLD FRONT IS SHOWN BY MODELS TO CROSS INTO FAR NORTHERN IL LATE
THIS AFTERNOON AND EARLY THIS EVENING RESULTING IN A WIND SHIFT
TO OUT OF THE NE-E AT 6-10KT.
MODELS OFFERING SIMILAR SOLUTIONS ON LARGE SCALE BUT DIFFERENCES
IN TIMING AND TRACK OF THE LOW OUT OF CENTRAL MO TO TO W CENTRAL
IL SAT AND SAT NIGHT STILL LEAVES QUESTIONS ABOUT HOW FAR N THE
RAIN WILL SPREAD AND HOW SOON IT WILL ARRIVE IN THE LOCAL AREA.
TREND OF MODELS HAS BEEN SLOWER AND A BIT FURTHER S OF PREVIOUS
FORECAST TRACKS. THIS DELAYS ARRIVAL OF ONSET OF RA AND KEEPS
HEAVIER RAIN S OF ORD AND MDW.
LOWER DEW POINT AIR BEHIND THE SLUGGISH COLD FRONT WILL BE
ADVECTED OVER THE LOCAL TERMINALS ON NE-E LOW LEVEL WINDS
BECOMING MODERATE TONIGHT BETWEEN HIGH PRESSURE BUILDING INTO THE
UPPER GREAT LAKES AND THE LOW RIDGE BETWEEN THE MO LOW. SLIGHTLY
MORE SOUTHWARD TRACK OF THE LOW AS IT MOVES INTO CENTRAL IL SUN
AND INFLUX OF LOWER LOW LEVEL POINTS IS EXPECTED TO DELAY AND
SIGNIFICANT THREAT OF SHRA/RA TIL LATER MORNING-EARLY AFTERNOON
ON SAT...THEN PERSISTING THROUGH THE DAY. WITH HEAVER RAIN
OCCURRING TO THE S OF THE TERMINALS AND THE FEED LOW DRIER LOW
LEVEL AIR EXPECT VFR CONDITIONS TO PREVAIL LOCALLY THOUGH MAY BE
AREAS MVFR BY MID-LATE SAT AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* MODERATE CONFIDENCE IN TIMING OF THE COLD FRONT PASSAGE THIS
EVENING AND THE ACCOMPANYING WIND SHIFT.
* HIGH CONFIDENCE IN VFR AND DRY CONDITIONS THROUGH THE NIGHT AND
EARLY SAT MORNING.
* MODERATE CONFIDENCE IN PREVAILING VFR CONTINUING FROM MID SAT
MORNING ON WITH ONLY AREAS/OCCASIONAL MVFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...
SUNDAY...CHC OF RA/SHRA. MVFR/IFR POSSIBLE.
MONDAY...SLGT CHC SHRA/TSRA. MVFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC SHRA/TSRA. OTHERWISE VFR.
RATZER
&&
.MARINE...
351 PM CDT
A COLD FRONT IS SLOWLY SINKING SOUTH ALONG LAKE MICHIGAN AND IS
CURRENTLY LOCATED FROM THE WI/IL STATE LINE THROUGH MUSKEGON. THE
FRONT WILL REACH SOUTHERN LAKE MICHIGAN THIS EVENING WITH WINDS
TURNING NORTH TO NORTHEAST AND GUSTING TO AROUND 20 KT. WINDS WILL
DIMINISH TO 10 TO 15 KT BEHIND THE FRONT AND VEER TO THE EAST BY
SATURDAY MORNING OVER THE SOUTHERN HALF OF THE LAKE. WINDS WILL BE
EAST ALONG THE ENTIRE LAKE BY SATURDAY NIGHT. THE PERSISTENT
EASTERLY FLOW WILL RESULT IN LOCALLY HIGHER WAVES ALONG THE SOUTHERN
WI AND IL COAST LINE OF 5 TO 8 FT BY SUNDAY AFTERNOON. WAVES IN THE
IL NEARSHORE ZONES LOOK LIKE THEY WILL STAY JUST BELOW SMALL CRAFT
ADVISORY CRITERIA...THEREFORE WILL REFRAIN FROM ISSUING A SCY NOW.
HOWEVER...THE HIGHER WAVES AND ONSHORE FLOW ALONG THE IL NEARSHORE
ZONES DO POSE AN INCREASED RIP CURRENT RISK. THE RISK ALSO IS
INCREASED BY THE FACT THERE WILL PROBABLY BE AN ABOVE AVERAGE NUMBER
OF SWIMMERS AT THE BEACH THIS HOLIDAY WEEKEND. ISSUED A RIP CURRENT
STATEMENT FOR THE IL SIDE OF THE LAKE SATURDAY MORNING THROUGH
SUNDAY EVENING.
HIGH PRESSURE SPREADS ACROSS THE WESTERN GREAT LAKES TONIGHT.
MEANWHILE LOW PRESSURE THAT WAS FORMALLY HURRICANE ISAAC IS MOVING
NORTHWARD. THE PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS WILL
TIGHTEN OVER SOUTHERN LAKE MICHIGAN. THEREFORE EAST WINDS WILL BE
STRONGER OVER THE SOUTHERN HALF OF THE LAKE. THE LOW WILL ENTER
SOUTH CENTRAL IL LATE SATURDAY AFTERNOON AND THEN TURN EASTWARD
PASSING SOUTH OF LAKE MICHIGAN. HIGH PRESSURE MOVES OVER THE LAKE
MONDAY NIGHT WITH WINDS WEAKENING ACROSS THE LAKE. ANOTHER TROUGH OF
LOW PRESSURE APPROACHES FROM THE WEST MID NEXT WEEK BUT CONFIDENCE
IS LOW ON THE EXACT TIMING OF THIS SYSTEM DUE TO GUIDANCE
INCONSISTENCIES.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
351 PM CDT FRI AUG 31 2012
.DISCUSSION...
349 PM CDT
MAIN FORECAST CONCERNS THIS FORECAST PERIOD REVOLVE AROUND PRECIP
CHANCES AND TRENDS...POSSIBLE HEAVY AT TIMES...THIS WEEKEND INTO
THE START OF NEXT WEEK AS REMNANTS OF TROPICAL STORM ISAAC WORK
ITS WAY NORTH ACROSS THE REGION.
IN THE NEAR TERM...LATEST SATELLITE IMAGERY DEPICTING EXPANSIVE
AREA OF MID AND HIGH LEVEL CLOUD COVER CONTINUING TO SPREAD
NORTHWARD ACROSS MUCH OF THE REGION AS THIS SYSTEM SLOWLY MOVES
NORTH. DESPITE AN INCREASE IN CLOUD COVER TODAY...MOSTLY SUNNY TO
PARTLY CLOUDY SKIES HAVE BEEN OBSERVED WITH TEMPERATURES RISING TO
THE LOWER 90S ACROSS NORTHERN ILLINOIS AND MID TO UPPER 80S ACROSS
AREAS SOUTH OF INTERSTATE 80. DESPITE LATEST RADAR IMAGERY SHOWING
SOME WEAK RETURNS FROM THE OUTER BANDS OF THIS SYSTEM ACROSS AREAS
FROM PONTIAC IN ILLINOIS EAST TO FOWLER IN INDIANA...MOST OF THIS
IS NOT REACHING THE GROUND. SOME DRIER AIR IS HELPING WITH THIS
BUT WITH A VERY MOIST AIRMASS ON ITS WAY...IT SHOULDNT TAKE MUCH
LONGER THIS EVENING BEFORE IT STARTS REACHING THE GROUND. OUTSIDE
OF THIS SYSTEM TO THE SOUTH...A COLD FRONT HAS BEEN DROPPING SOUTH
THROUGH PORTIONS OF WISCONSIN TODAY. ALTHOUGH...EXPECT THIS FRONT
TO LOSE ITS SOUTHWARD MOMENTUM THIS EVENING AND THEN BECOME MORE
DIFFUSE AS THE SYSTEM TO THE SOUTH MOVES INTO THE AREA. DESPITE
THIS FRONT ACROSS THE REGION...ANY VERTICAL DEVELOPMENT HAS BEEN
LIMITED AND IS EXPECTED TO REMAIN THIS WAY AS A MORE SUBSIDENT
LARGE SCALE ENVIRONMENT REMAINS OVER THIS BOUNDARY.
SHIFTING TOWARD MAIN FOCUS OF THIS FORECAST PERIOD...REMNANTS OF
TROPICAL STORM ISAAC CONTINUE TO SLOWLY SHIFT NORTH THROUGH
MISSOURI THIS AFTERNOON. THIS SYSTEM IS MARKED WITH A VERY MOIST
ENVIRONMENT...OR A TROPICAL ENVIRONMENT. COPIOUS AMOUNTS OF
MOISTURE WITH 12Z SOUNDINGS ACROSS MISSOURI INDICATING PWATS
AROUND 2.4 INCHES THIS MORNING...AND LATEST RUC ANALYSIS SHOWING
THIS AXIS OF HIGHER PWATS EXTENDING FROM THE ST. LOUIS AREA BACK
SOUTH THROUGH MISSOURI INTO ARKANSAS. WITH A SLOW MOVEMENT OF THIS
SYSTEM TONIGHT...THIS AXIS OF HIGHEST MOISTURE WILL ALSO SHIFT
SLOWLY. NONETHELESS...THESE OUTWARD BANDS OF THIS SYSTEM AND
HIGHER MOISTURE CONTENT AIR WILL LIFT NORTH OVERNIGHT. THIS SHOULD
HELP BRING SHOWERS ACROSS THE SOUTHERN CWA PRIMARILY FOR AREAS
ALONG AND SOUTH OF A LINE FROM PONTIAC IN ILLINOIS TO RENSSELAER
IN INDIANA. HEAVIER DOWNPOURS ARE NOT EXPECTED TONIGHT AS WELL AS
ANY THUNDER. DESPITE SOME INSTABILITY IN PLACE...THESE INITIAL
SHOWERS WILL BE WEAKLY FORCED. ITS NOT UNTIL SATURDAY THROUGH THE
REMAINDER OF THE WEEKEND THAT THE MAIN AXIS OF HIGHEST MOISTURE
AND RAINFALL WILL REACH THE CWA. WITH BETTER FORCING WITH THIS
SYSTEM SHIFTING NORTH AND SREF GUIDANCE INDICATING THAT THE AXIS
OF HIGHER PWATS/MUCH HIGHER DEWPOINT AIR WILL REACH THE SOUTHERN
CWA...THE POTENTIAL FOR HEAVIER RAIN WILL INCREASE. DESPITE SOME
MODEL VARIABILITY WITH THE OVERALL EVOLUTION OF THIS
SYSTEM...CONFIDENCE IS HIGH FOR AREAS ALONG AND SOUTH OF
INTERSTATE 80 TO RECEIVE THE HIGHEST AMOUNTS OF RAIN THIS WEEKEND.
WHERE CONFIDENCE IS LOWER AT THIS TIME IS IN REGARDS TO HOW FAR
NORTH THIS RAIN WILL WORK ITS WAY NORTH. AS A FAIRLY TIGHT
GRADIENT IS EXPECTED WITH THIS PRECIP SHIELD THIS WEEKEND...HAVE
TRIED TO CONVEY THIS AS BEST AS POSSIBLE IN THE GRIDS. IF THIS
SYSTEM WERE TO SHIFT NORTHWARD THAN PREVIOUSLY THOUGHT...THEN THIS
AXIS OF RAINFALL WOULD OF COURSE SHIFT NORTH ACROSS THE CWA. AT
THIS POINT IT APPEARS THAT A DRASTIC CUTOFF IN PRECIP SHOULD OCCUR
AROUND THE I88 CORRIDOR. IN ALL AREAS ACROSS OUR CWA ARE EXPECTED
TO RECEIVE A LARGE AMOUNT OF RAINFALL THROUGH SUNDAY NIGHT...WITH
THE POTENTIAL FOR AMOUNTS OF 4 TO 5 INCHES OR GREATER ALONG AND
SOUTH OF A LINE FROM THE PONTIAC AREA TO THE RENSSELAER AREA.
MOVING NORTH OF THIS LINE...RAINFALL AMOUNTS ARE EXPECTED TO TAPER
FROM AROUND 3 TO 4 INCHES TO AROUND 1 INCH JUST NORTH OF THE
INTERSTATE 80 CORRIDOR. EXPECTED AMOUNTS ALONG THE INTERSTATE 88
CORRIDOR WILL ROUGHLY RANGE FROM THREE QUARTERS OF AN INCH UP TO
ONE INCH...WITH THE POTENTIAL FOR LITTLE OR NO RAIN IN THE
COUNTIES BORDERING WISCONSIN...GENERALLY UNDER A QUARTER INCH. NO
HEADLINES AT THIS TIME BUT WILL CONTINUE THE ESF TODAY.
RODRIGUEZ
&&
.HYDROLOGY...
441 AM CDT
NOT MUCH HAS CHANGED WITH THE TRACK OF THE REMNANTS OF TROPICAL
CYCLONE ISAAC. THE SYSTEM IS EXPECTED TO TRACK FROM ITS CURRENT
POSITION ACROSS WEST CENTRAL ARKANSAS...NORTHWARD TO CENTRAL
MISSOURI BY EARLY SATURDAY...AND THEN TRANSITION TO THE EAST ALONG
THE INTERSTATE 70 CORRIDOR THIS WEEKEND. DUE TO THE TROPICAL
NATURE OF THE STORM SYSTEM...A VERY HIGH AMOUNT OF ATMOSPHERIC
MOISTURE WILL ACCOMPANY THE SYSTEM. BECAUSE OF THIS...IT APPEARS
LIKELY THAT PERIODS OF HEAVY RAINFALL WILL OCCUR ACROSS CENTRAL
ILLINOIS AND PORTIONS OF NORTHWESTERN INDIANA ON SATURDAY THROUGH
SUNDAY. THE LATEST FORECAST TOTAL RAINFALL AMOUNTS CALLS FOR
BETWEEN THREE TO SIX INCHES ACROSS THE FAR SOUTHERN COUNTIES OF THE
CWA...LIVINGSTON/FORD/IROQUOIS/BENTON...WITH AMOUNTS DROPPING OFF
RAPIDLY TO THE NORTH. IT IS POSSIBLE THAT LOCATIONS NEAR THE
WISCONSIN BORDER MAY SEE VERY LITTLE RAINFALL.
THE RIVER BASINS MOSTLY LIKELY TO SEE THE GREATEST IMPACT WILL BE
THE KANKAKEE...IROQUOIS AND VERMILION RIVERS AND SMALLER RIVERS
AND CREEKS DRAINING INTO THEM. GIVEN THE SLOW MOVEMENT TO THE
SYSTEM AND THE COPIOUS AMOUNTS OF DEEP LAYER MOISTURE LIKELY TO BE
PRESENT...WIDESPREAD RAINFALL AMOUNTS OF 2 INCHES PER SIX HOUR
PERIOD IS POSSIBLE...AND LOCALLY HIGHER AMOUNTS ARE CERTAINLY NOT
OUT OF THE QUESTION. THIS AREA WILL NEED TO BE UNDER CONSIDERATION
FOR AN AREAL FLOOD WARNING
FOR LOCATIONS NORTH OF THE HEAVY RAINFALL AXIS...NORTHWARD TO THE
I-88 CORRIDOR...1 TO 2 INCHES OF TOTAL RAINFALL IS POSSIBLE AND
THE MORE FLASHY BASINS OF THE SOUTHERN PORTIONS OF THE CHICAGO
METRO AREA COULD SEE FLOODING PROBLEMS AS WELL.
KREIN/KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* TIMING WIND SHIFT FROM WSW TO NE WITH COLD FRONT SINKING FROM
SE AND FAR SW WI DOWN ACROSS THE LOCAL AREA TOWARD EVENING.
* TIMING ONSET AND NORTHWARD EXTEND OF SHOWERS/RAIN ASSOCIATED
WITH T.D. ISAAC ON SAT.
TRS
//DISCUSSION...UPDATED 18Z...
MODERATE SW-WSW LOW LEVEL FLOW HAS BEEN MIXING DOWN TO THE
SURFACE WITH THE SKC CONDITIONS ALLOWING MAXIMUM HEATING THROUGH
MIDDAY RESULTING IN SOME GUSTS IN THE 15-20KT RANGE THIS MORNING.
OUTER EDGE OF CLOUD SHIELD OF THE T.D. CENTERED OVER SW MO HAVE
SPREAD TO THE WI BORDER BY EARLY AFTERNOON WITH THICKER CIRRUS
STRATUS TO SPREAD ACROSS THE LOCAL AREA DURING THE MID TO LATE
AFTERNOON.
WITH THICKENING HIGH CLOUDS ADDITIONAL INSOLATION WILL BE
DECREASING THIS AFTERNOON...AND AS THE COLD FRONT ACROSS SOUTHERN
WI CONTINUES TO CREEP SOUTHWARD THE SURFACE PRESSURE GRADIENT
SLACKENS DURING THE AFTERNOON. WITH DECREASE IN BOTH SURFACE
HEATING AND IN SURFACE PRESSURE GRADIENT SW-WSW WINDS WILL LOSE
ANY MARGINAL GUSTS AND SETTLE TO SUSTAINED 10-12KT TIL DUSK. THE
COLD FRONT IS SHOWN BY MODELS TO CROSS INTO FAR NORTHERN IL LATE
THIS AFTERNOON AND EARLY THIS EVENING RESULTING IN A WIND SHIFT
TO OUT OF THE NE-E AT 6-10KT.
MODELS OFFERING SIMILAR SOLUTIONS ON LARGE SCALE BUT DIFFERENCES
IN TIMING AND TRACK OF THE LOW OUT OF CENTRAL MO TO TO W CENTRAL
IL SAT AND SAT NIGHT STILL LEAVES QUESTIONS ABOUT HOW FAR N THE
RAIN WILL SPREAD AND HOW SOON IT WILL ARRIVE IN THE LOCAL AREA.
TREND OF MODELS HAS BEEN SLOWER AND A BIT FURTHER S OF PREVIOUS
FORECAST TRACKS. THIS DELAYS ARRIVAL OF ONSET OF RA AND KEEPS
HEAVIER RAIN S OF ORD AND MDW.
LOWER DEW POINT AIR BEHIND THE SLUGGISH COLD FRONT WILL BE
ADVECTED OVER THE LOCAL TERMINALS ON NE-E LOW LEVEL WINDS
BECOMING MODERATE TONIGHT BETWEEN HIGH PRESSURE BUILDING INTO THE
UPPER GREAT LAKES AND THE LOW RIDGE BETWEEN THE MO LOW. SLIGHTLY
MORE SOUTHWARD TRACK OF THE LOW AS IT MOVES INTO CENTRAL IL SUN
AND INFLUX OF LOWER LOW LEVEL POINTS IS EXPECTED TO DELAY AND
SIGNIFICANT THREAT OF SHRA/RA TIL LATER MORNING-EARLY AFTERNOON
ON SAT...THEN PERSISTING THROUGH THE DAY. WITH HEAVER RAIN
OCCURRING TO THE S OF THE TERMINALS AND THE FEED LOW DRIER LOW
LEVEL AIR EXPECT VFR CONDITIONS TO PREVAIL LOCALLY THOUGH MAY BE
AREAS MVFR BY MID-LATE SAT AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN WIND TRENDS.
* MODERATE CONFIDENCE IN TIMING OF THE COLD FRONT PASSAGE THIS
EVENING AND THE ACCOMPANYING WIND SHIFT.
* HIGH CONFIDENCE IN VFR AND DRY CONDITIONS THROUGH THE NIGHT AND
EARLY SAT MORNING.
* MODERATE CONFIDENCE IN PREVAILING VFR CONTINUING FROM MID SAT
MORNING ON WITH ONLY AREAS/OCCASIONAL MVFR.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...
SUNDAY...CHC OF RA/SHRA. MVFR/IFR POSSIBLE.
MONDAY...SLGT CHC SHRA/TSRA. MVFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC SHRA/TSRA. OTHERWISE VFR.
RATZER
&&
.MARINE...
246 AM CDT
MARINE FORECAST CONCERNS INCLUDE A PERIOD OF GUSTY SOUTHWEST WINDS
THIS MORNING AHEAD OF A COLD FRONT WHICH WILL SAG SOUTH ACROSS LAKE
MICHIGAN TODAY...AND A PERIOD OF MODEST EAST-NORTHEAST WINDS THIS
THE WEEKEND AS THE SURFACE LOW PRESSURE CIRCULATION ASSOCIATED WITH
TROPICAL DEPRESSION ISAAC MOVES SLOWLY SOUTH OF THE GREAT LAKES.
LOW PRESSURE WAS LOCATED OVER EASTERN QUEBEC EARLY THIS
MORNING...WITH A COLD FRONT TRAILING SOUTHWESTWARD ACROSS THE
NORTHERN LAKES AND INTO CENTRAL WISCONSIN. THIS COLD FRONT WILL
CONTINUE TO SAG SOUTH ACROSS LAKE MICHIGAN TODAY AS THE EASTERN
CANADIAN LOW CONTINUES TO MOVE AWAY. SOUTHWEST WINDS AHEAD OF THE
FRONT HAVE BEEN FAIRLY GUST PARTICULARLY OVER THE NORTHERN END OF
LAKE MICHIGAN...WITH SOME GUSTS AROUND 30 KTS NOTED ALONG THE
EASTERN SHORE NORTH OF MANISTEE AND AROUND CHARLEVOIX. THESE
STRONGER WINDS SHOULD DIMINISH THIS MORNING...AS THE LOW LEVEL JET
ASSOCIATED WITH A PASSING UPPER DISTURBANCE PULLS OF TO THE EAST.
WINDS WILL VEER TO THE NORTH BEHIND THE FRONT TODAY AND TO
NORTH-NORTHEAST TONIGHT...AS THE FRONT CONTINUES TO DRIFT TO THE
SOUTH AND HIGH PRESSURE SPREADS ACROSS THE NORTHERN LAKES. THE HIGH
WILL DRIFT SOUTHEAST ACROSS THE NORTHERN/EASTERN LAKES SATURDAY AND
SUNDAY...WHILE THE AREA OF SURFACE LOW PRESSURE FROM TROPICAL
DEPRESSION ISAAC SLOWLY LIFTS ACROSS THE LOWER MISSOURI VALLEY
THROUGH TONIGHT...THEN TURNS EAST AND DRIFTS ACROSS SOUTH CENTRAL
IL/IND AS IT FILLS DURING THE REMAINDER OF THE WEEKEND. FORECAST
MODEL GUIDANCE CONTINUES TO EXHIBIT DIFFERENCES IN THE EXACT AND
STRENGTH OF ISAAC DURING THIS PERIOD...THOUGH THE PASSAGE OF THIS
LOW SOUTH OF THE LAKES SHOULD RESULT IN A PERIOD OF ENHANCED
EASTERLY FLOW PARTICULARLY ON THE SOUTHERN HALF OF LAKE MICHIGAN
ESPECIALLY LATE TONIGHT INTO SUNDAY. EAST WINDS TOPPING OUT IN THE
20-25 KT RANGE DURING THIS PERIOD MAY NECESSITATE SMALL CRAFT
ADVISORIES ALONG THE WESTERN SHORE OF SOUTHERN LAKE MICHIGAN OVER
THE WEEKEND...BEFORE THE LOW WEAKENS AND LOOSENS THE GRADIENT ACROSS
THE LAKE BY MONDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1112 AM CDT FRI AUG 31 2012
.DISCUSSION...
340 AM CDT
THE MAIN FORECAST CONCERNS CONTINUE TO CENTER ON THE HEAVY RAINFALL
POTENTIAL ACROSS PORTIONS OF THE AREA THIS WEEKEND AS THE REMNANTS
OF HURRICANE ISSAC MOVE ACROSS THE CENTRAL MISSISSIPPI
VALLEY. I HAVE FOLLOWED CLOSER TO THE 00 UTC ECMWF...GFS AND UKMET
FOR THIS FORECAST PERIOD AS THEY HAVE A DECENT HANDLE ON TRACKING
THE REMNANTS UP ACROSS EAST CENTRAL MISSOURI EASTWARD ACROSS
CENTRAL ILLINOIS. THE NAM SOLUTION WAS REJECTED AS IT IS DOING A
POOR JOB WITH THE SYSTEM.
NO BIG CHANGES TO THE PREVIOUS THINKING. THE CENTER OF THE STORM IS
NOW LOCATED ACROSS WEST CENTRAL ARKANSAS. IT WILL SLOWLY LIFT
NORTHWARD ACROSS SOUTHWESTERN MISSOURI LATER THIS AFTERNOON AND THEN
THE SYSTEM IS EXPECTED TO BEGIN TO MOVE MORE EASTERLY LATER TONIGHT
AS IT BECOMES INFLUENCED BY THE WESTERLIES. IT STILL APPEARS THE
CENTER OF THE SYSTEM WILL PASS SOMEWHERE AROUND OR JUST NORTH OF THE
ST LOUIS AREA AND TRANSVERSE THE CENTRAL SECTIONS OF ILLINOIS.
ULTIMATELY THIS WILL RESULT IN THE HEAVIEST RAINFALL ACROSS MY
SOUTHERN COUNTIES...SOUTH OF INTERSTATE 80. IT APPEARS THERE WILL BE
A VERY SHARPE GRADIENT ACROSS NORTHERN ILLINOIS SOMEWHERE AROUND THE
I 88 CORRIDOR. THE NORTHERN SUBURBS OF CHICAGO MAY ONLY GET MINOR
AMOUNTS UP TO A QUARTER INCH...WHILE THE SOUTHERN BURBS GET MORE
THAN AN INCH. BY FAR THE HEAVIEST AMOUNTS LOOK TO BE ACROSS MY
SOUTHERN COUNTIES FROM SOUTHERN LA SALLE EASTWARD THROUGH KANKAKEE
AND POINTS SOUTH. IN THESE AREAS 3 TO 6 INCHES ARE POSSIBLE...WITH
LOCALLY HIGH AMOUNTS POSSIBLE. DUE TO THE EXPECTED RAINFALL...I
LOWER TEMPERATURES INTO THE 70S FOR HIGHS...MANY SOUTH FOR SATURDAY
AND SUNDAY. THE HEAVY RAIN THREAT WILL END FROM WEST TO EAST ON
LATER ON SUNDAY AS THE SYSTEM MOVE EAST AND RAPIDLY WEAKENS.
IN THE EXTENDED PERIOD OVERALL CONFIDENCE IS LOW AS IT APPEARS THE
WESTERLIES WILL BECOME ACTIVE ACROSS NORTH AMERICA. THIS WILL LIKELY
DRIVE A COUPLE OF POTENT MID/UPPER TROUGHS ACROSS SOUTHERN CANADA.
THE GUIDANCE SUGGESTS THAT A TROUGH WILL TRY TO DIG ACROSS THE NORTH
CENTRAL CONUS BY MID TO LATE WEEK. HOWEVER...THERE IS A SIGNIFICANT
AMOUNT OF SPREAD AMONGST THE MODEL ENSEMBLES...INDICATING LARGE
TIMING UNCERTAINTIES. IT DOES APPEAR THERE WILL BE A CHANCE OF
THUNDERSTORMS SOMETIME EITHER WEDNESDAY NIGHT OR THURSDAY AS A COLD
FRONT DROPS ACROSS THE AREA. TEMPERATURES DURING THE PERIOD WILL
LIKELY BE NEAR AVERAGE EARLY ON IN THE WEEK...THEN TRENDING TO BELOW
AVERAGE AS A COOL AIR MASS LOOKS TO SET UP ACROSS THE REGION BEHIND
THIS COLD FRONT.
KJB
&&
.HYDROLOGY...
441 AM CDT
NOT MUCH HAS CHANGED WITH THE TRACK OF THE REMNANTS OF TROPICAL
CYCLONE ISAAC. THE SYSTEM IS EXPECTED TO TRACK FROM ITS CURRENT
POSITION ACROSS WEST CENTRAL ARKANSAS...NORTHWARD TO CENTRAL
MISSOURI BY EARLY SATURDAY...AND THEN TRANSITION TO THE EAST ALONG
THE INTERSTATE 70 CORRIDOR THIS WEEKEND. DUE TO THE TROPICAL
NATURE OF THE STORM SYSTEM...A VERY HIGH AMOUNT OF ATMOSPHERIC
MOISTURE WILL ACCOMPANY THE SYSTEM. BECAUSE OF THIS...IT APPEARS
LIKELY THAT PERIODS OF HEAVY RAINFALL WILL OCCUR ACROSS CENTRAL
ILLINOIS AND PORTIONS OF NORTHWESTERN INDIANA ON SATURDAY THROUGH
SUNDAY. THE LATEST FORECAST TOTAL RAINFALL AMOUNTS CALLS FOR
BETWEEN THREE TO SIX INCHES ACROSS THE FAR SOUTHERN COUNTIES OF THE
CWA...LIVINGSTON/FORD/IROQUOIS/BENTON...WITH AMOUNTS DROPPING OFF
RAPIDLY TO THE NORTH. IT IS POSSIBLE THAT LOCATIONS NEAR THE
WISCONSIN BORDER MAY SEE VERY LITTLE RAINFALL.
THE RIVER BASINS MOSTLY LIKELY TO SEE THE GREATEST IMPACT WILL BE
THE KANKAKEE...IROQUOIS AND VERMILLION RIVERS AND SMALLER RIVERS
AND CREEKS DRAINING INTO THEM. GIVEN THE SLOW MOVEMENT TO THE
SYSTEM AND THE COPIOUS AMOUNTS OF DEEP LAYER MOISTURE LIKELY TO BE
PRESENT...WIDESPREAD RAINFALL AMOUNTS OF 2 INCHES PER SIX HOUR
PERIOD IS POSSIBLE...AND LOCALLY HIGHER AMOUNTS ARE CERTAINLY NOT
OUT OF THE QUESTION. THIS AREA WILL NEED TO BE UNDER CONSIDERATION
FOR AN AREAL FLOOD WARNING
FOR LOCATIONS NORTH OF THE HEAVY RAINFALL AXIS...NORTHWARD TO THE
I-88 CORRIDOR...1 TO 2 INCHES OF TOTAL RAINFALL IS POSSIBLE AND
THE MORE FLASHY BASINS OF THE SOUTHERN PORTIONS OF THE CHICAGO
METRO AREA COULD SEE FLOODING PROBLEMS AS WELL.
KREIN/KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* MARGINAL GUSTINESS OF 15-20 KT TIL THICK CIRRUS STRATUS
OVERSPREADS AROUND NOON.
* TIMING WIND SHIFT FROM WSW TO NE WITH COLD FRONT SINKING FROM
SE AND FAR SW WI DOWN ACROSS AREA TOWARD EVENING.
* SMALL POTENTIAL FOR SHRA/ISOLD TS FAR SOUTHERN WI INTO NE AND
FAR N CENTRAL IL BORDER MID-LATE AFTERNOON.
* POTENTIAL FOR SHOWERS ASSOCIATED WITH TD ISAAC MAINLY BEYOND
12Z SATURDAY.
TRS
//DISCUSSION...UPDATED 14Z...
ONLY VERY MINOR TWEAKS MADE TO 14Z TAFOR. SSW-SW LOW LEVEL WINDS
ADVECTING MID-UPPER 60S SURFACE DEW POINTS OVER THE AREA AT MID
MORNING WITH UPPER 60-LOWER 70S ACROSS CENTRAL IL. WITH CONTINUED
HEATING DURING THE LATE MORNING THE LOW LEVEL MOISTURE ADVECTION
WILL BE OFFSET BY DEEPENING OF MIXING IN THE BOUNDARY LAYER.
EXPECT DEW POINTS TO BE IN THE MID-UPPER 60S DURING THE
AFTERNOON. THIS GIVES CONVECTIVE TEMPERATURES IN THE UPPER 80S
WHICH IS FORECAST TO REACH AROUND NOON. THOUGH NOT OPERATIONALLY
SIGNIFICANT DID INCLUDE A FORECAST STARTING AT 17Z INCLUDING
HIGHER BASED CU DEVELOPING.
MODELS SHOW LOW LEVEL CONVERGENCE ALONG THE WI COLD FRONT
DROPPING TOWARD THE IL BORDER THIS AFTERNOON...AS WELL AS IN NE
ALONG A LAKE BREEZE BOUNDARY PUSHING INLAND. FORECAST SOUNDINGS
FROM THE 12Z RUC13 SHOW MINIMAL CIN OVER CHI AREA DURING THE
LATER AFTERNOON ALONG WITH DECENT CAPE VALUES. LOW LEVEL WARMING
AND CONVERGENCE WOULD FAVOR ISOLD TO SCT TS DEVELOPMENT ALONG THE
COLD FRONT AND LAKE BREEZE MID-LATE AFTERNOON...WHILE SUBSIDENCE
INN THE MID AND UPPER LEVELS ON THE PERIPHERY OF ISSAC REMNANTS
SPREAD OVER THE LOCAL AREA. THIS WITH INCREASING CLOUDS CUTTING
SURFACE HEATING DURING THE LATER AFTERNOON WOULD DISCOURAGE AN TS
DEVELOPMENT. THREAT TOO LOW AT THIS TIME TO INCLUDE ANY MENTION
IN TAFOR THOUGH LOW COVERAGE NOT TS LATE AFTERNOON NOT TOTALLY
OUT OF THE QUESTION.
TRS
PREVIOUS DISCUSSION...UPDATED 12Z...
LITTLE CHANGE IN AVIATION FORECAST THINKING FROM 06Z ISSUANCE.
MAIN FOCUS REMAINS ON TIMING OF WEAK COLD FRONT AND WIND SHIFT
FROM WEST-SOUTHWEST TO NORTHEAST TOWARD EVENING...THEN INCREASING
HIGH CLOUDS THIS AFTERNOON AND EVENTUAL PRECIP POTENTIAL SATURDAY
AS THE REMAINS OF TROPICAL DEPRESSION ISAAC MOVE SLOWLY INTO
IL/IND.
THE COLD FRONT...WHICH WAS FROM EAST CENTRAL WI TO NORTH CENTRAL
IA AT 11Z...WILL CONTINUE TO MOVE SLOWLY SOUTH TOWARD THE
TERMINALS TODAY. VAD WIND PROFILES INDICATE THE PRESENCE OF A 35
KT SPEED MAX ABOVE THE BOUNDARY LAYER AT AROUND 1000 FT AGL THIS
MORNING WHICH WILL RESULT IN A PERIOD OF MARGINAL LLWS FOR THE
NEXT HOUR OR TWO UNTIL THE BOUNDARY LAYER BECOMES MORE DEEPLY
MIXED. WITH MIXING...SOUTHWEST WINDS WILL BECOME A BIT BREEZY BY
MID-MORNING WITH GUSTS APPROACHING 20 KTS. THE GRADIENT SHOULD
WEAKEN THIS AFTERNOON AS THE COLD FRONTAL TROUGH APPROACHES
HOWEVER...ALLOWING WINDS TO DECREASE A BIT. TIMING OF THE FRONTAL
PASSAGE AND A WIND SHIFT FROM WEST-SOUTHWEST TO NORTHEAST STILL
APPEARS TO BE ON TRACK FOR THE 23-01Z PERIOD ACROSS THE
TERMINALS...WITH WINDS REMAINING NORTHEAST AROUND 10 KTS
OVERNIGHT.
ATTENTION THEN TURNS TO THE REMAINS OF ISAAC...WHICH LIFT SLOWLY
ACROSS THE MISSOURI VALLEY TODAY...THEN DRIFT EAST ACROSS CENTRAL
IL/IND SAT. THIS SYSTEM SHOULD PRODUCE JUST INCREASING HIGH/MID
CLOUDS ACROSS THE AREA LATER TODAY AND TONIGHT...WITH GUIDANCE
INDICATING RAIN SHOWERS MOVING INTO THE TERMINALS GENERALLY AFTER
12Z SATURDAY MORNING. ALL MODELS INDICATE A SHARP NORTHERN CUTOFF
TO THE PRECIP...WITH THAT CUTOFF LIKELY SOMEWHERE OVER NORTHERN
IL. AT THIS DISTANCE HAVE INDICATED A VICINITY SHOWER MENTION FOR
ORD IN THE FINAL HOURS OF THE 30 HR FORECAST...WITH ROOM FOR
FURTHER DEFINITION IN SUBSEQUENT FORECASTS. WITH THE LOW PRESSURE
CENTER MOVING INTO IL...THE PRESSURE GRADIENT LOOKS TO TIGHTEN
ENOUGH FOR WINDS TO COME UP INTO THE 10-15 KT RANGE SATURDAY
MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN WIND TRENDS PRIOR TO WIND SHIFT TOWARD
EVENING.
* MEDIUM CONFIDENCE IN WIND SHIFT TIMING WITH COLD FRONT.
* MEDIUM CONFIDENCE IN SHOWERS REMAINING S OF ORD/MDW THROUGH 12Z
SAT.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...
SUNDAY...CHC OF RA/SHRA. MVFR/IFR POSSIBLE.
MONDAY...SLGT CHC SHRA/TSRA. MVFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC SHRA/TSRA. OTHERWISE VFR.
RATZER
&&
.MARINE...
246 AM CDT
MARINE FORECAST CONCERNS INCLUDE A PERIOD OF GUSTY SOUTHWEST WINDS
THIS MORNING AHEAD OF A COLD FRONT WHICH WILL SAG SOUTH ACROSS LAKE
MICHIGAN TODAY...AND A PERIOD OF MODEST EAST-NORTHEAST WINDS THIS
THE WEEKEND AS THE SURFACE LOW PRESSURE CIRCULATION ASSOCIATED WITH
TROPICAL DEPRESSION ISAAC MOVES SLOWLY SOUTH OF THE GREAT LAKES.
LOW PRESSURE WAS LOCATED OVER EASTERN QUEBEC EARLY THIS
MORNING...WITH A COLD FRONT TRAILING SOUTHWESTWARD ACROSS THE
NORTHERN LAKES AND INTO CENTRAL WISCONSIN. THIS COLD FRONT WILL
CONTINUE TO SAG SOUTH ACROSS LAKE MICHIGAN TODAY AS THE EASTERN
CANADIAN LOW CONTINUES TO MOVE AWAY. SOUTHWEST WINDS AHEAD OF THE
FRONT HAVE BEEN FAIRLY GUST PARTICULARLY OVER THE NORTHERN END OF
LAKE MICHIGAN...WITH SOME GUSTS AROUND 30 KTS NOTED ALONG THE
EASTERN SHORE NORTH OF MANISTEE AND AROUND CHARLEVOIX. THESE
STRONGER WINDS SHOULD DIMINISH THIS MORNING...AS THE LOW LEVEL JET
ASSOCIATED WITH A PASSING UPPER DISTURBANCE PULLS OF TO THE EAST.
WINDS WILL VEER TO THE NORTH BEHIND THE FRONT TODAY AND TO
NORTH-NORTHEAST TONIGHT...AS THE FRONT CONTINUES TO DRIFT TO THE
SOUTH AND HIGH PRESSURE SPREADS ACROSS THE NORTHERN LAKES. THE HIGH
WILL DRIFT SOUTHEAST ACROSS THE NORTHERN/EASTERN LAKES SATURDAY AND
SUNDAY...WHILE THE AREA OF SURFACE LOW PRESSURE FROM TROPICAL
DEPRESSION ISAAC SLOWLY LIFTS ACROSS THE LOWER MISSOURI VALLEY
THROUGH TONIGHT...THEN TURNS EAST AND DRIFTS ACROSS SOUTH CENTRAL
IL/IND AS IT FILLS DURING THE REMAINDER OF THE WEEKEND. FORECAST
MODEL GUIDANCE CONTINUES TO EXHIBIT DIFFERENCES IN THE EXACT AND
STRENGTH OF ISAAC DURING THIS PERIOD...THOUGH THE PASSAGE OF THIS
LOW SOUTH OF THE LAKES SHOULD RESULT IN A PERIOD OF ENHANCED
EASTERLY FLOW PARTICULARLY ON THE SOUTHERN HALF OF LAKE MICHIGAN
ESPECIALLY LATE TONIGHT INTO SUNDAY. EAST WINDS TOPPING OUT IN THE
20-25 KT RANGE DURING THIS PERIOD MAY NECESSITATE SMALL CRAFT
ADVISORIES ALONG THE WESTERN SHORE OF SOUTHERN LAKE MICHIGAN OVER
THE WEEKEND...BEFORE THE LOW WEAKENS AND LOOSENS THE GRADIENT ACROSS
THE LAKE BY MONDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 AM CDT FRI AUG 31 2012
.DISCUSSION...
340 AM CDT
THE MAIN FORECAST CONCERNS CONTINUE TO CENTER ON THE HEAVY RAINFALL
POTENTIAL ACROSS PORTIONS OF THE AREA THIS WEEKEND AS THE REMNANTS
OF HURRICANE ISSAC MOVE ACROSS THE CENTRAL MISSISSIPPI
VALLEY. I HAVE FOLLOWED CLOSER TO THE 00 UTC ECMWF...GFS AND UKMET
FOR THIS FORECAST PERIOD AS THEY HAVE A DECENT HANDLE ON TRACKING
THE REMNANTS UP ACROSS EAST CENTRAL MISSOURI EASTWARD ACROSS
CENTRAL ILLINOIS. THE NAM SOLUTION WAS REJECTED AS IT IS DOING A
POOR JOB WITH THE SYSTEM.
NO BIG CHANGES TO THE PREVIOUS THINKING. THE CENTER OF THE STORM IS
NOW LOCATED ACROSS WEST CENTRAL ARKANSAS. IT WILL SLOWLY LIFT
NORTHWARD ACROSS SOUTHWESTERN MISSOURI LATER THIS AFTERNOON AND THEN
THE SYSTEM IS EXPECTED TO BEGIN TO MOVE MORE EASTERLY LATER TONIGHT
AS IT BECOMES INFLUENCED BY THE WESTERLIES. IT STILL APPEARS THE
CENTER OF THE SYSTEM WILL PASS SOMEWHERE AROUND OR JUST NORTH OF THE
ST LOUIS AREA AND TRANSVERSE THE CENTRAL SECTIONS OF ILLINOIS.
ULTIMATELY THIS WILL RESULT IN THE HEAVIEST RAINFALL ACROSS MY
SOUTHERN COUNTIES...SOUTH OF INTERSTATE 80. IT APPEARS THERE WILL BE
A VERY SHARPE GRADIENT ACROSS NORTHERN ILLINOIS SOMEWHERE AROUND THE
I 88 CORRIDOR. THE NORTHERN SUBURBS OF CHICAGO MAY ONLY GET MINOR
AMOUNTS UP TO A QUARTER INCH...WHILE THE SOUTHERN BURBS GET MORE
THAN AN INCH. BY FAR THE HEAVIEST AMOUNTS LOOK TO BE ACROSS MY
SOUTHERN COUNTIES FROM SOUTHERN LA SALLE EASTWARD THROUGH KANKAKEE
AND POINTS SOUTH. IN THESE AREAS 3 TO 6 INCHES ARE POSSIBLE...WITH
LOCALLY HIGH AMOUNTS POSSIBLE. DUE TO THE EXPECTED RAINFALL...I
LOWER TEMPERATURES INTO THE 70S FOR HIGHS...MANY SOUTH FOR SATURDAY
AND SUNDAY. THE HEAVY RAIN THREAT WILL END FROM WEST TO EAST ON
LATER ON SUNDAY AS THE SYSTEM MOVE EAST AND RAPIDLY WEAKENS.
IN THE EXTENDED PERIOD OVERALL CONFIDENCE IS LOW AS IT APPEARS THE
WESTERLIES WILL BECOME ACTIVE ACROSS NORTH AMERICA. THIS WILL LIKELY
DRIVE A COUPLE OF POTENT MID/UPPER TROUGHS ACROSS SOUTHERN CANADA.
THE GUIDANCE SUGGESTS THAT A TROUGH WILL TRY TO DIG ACROSS THE NORTH
CENTRAL CONUS BY MID TO LATE WEEK. HOWEVER...THERE IS A SIGNIFICANT
AMOUNT OF SPREAD AMONGST THE MODEL ENSEMBLES...INDICATING LARGE
TIMING UNCERTAINTIES. IT DOES APPEAR THERE WILL BE A CHANCE OF
THUNDERSTORMS SOMETIME EITHER WEDNESDAY NIGHT OR THURSDAY AS A COLD
FRONT DROPS ACROSS THE AREA. TEMPERATURES DURING THE PERIOD WILL
LIKELY BE NEAR AVERAGE EARLY ON IN THE WEEK...THEN TRENDING TO BELOW
AVERAGE AS A COOL AIR MASS LOOKS TO SET UP ACROSS THE REGION BEHIND
THIS COLD FRONT.
KJB
&&
.HYDROLOGY...
441 AM CDT
NOT MUCH HAS CHANGED WITH THE TRACK OF THE REMNANTS OF TROPICAL
CYCLONE ISAAC. THE SYSTEM IS EXPECTED TO TRACK FROM ITS CURRENT
POSITION ACROSS WEST CENTRAL ARKANSAS...NORTHWARD TO CENTRAL
MISSOURI BY EARLY SATURDAY...AND THEN TRANSITION TO THE EAST ALONG
THE INTERSTATE 70 CORRIDOR THIS WEEKEND. DUE TO THE TROPICAL
NATURE OF THE STORM SYSTEM...A VERY HIGH AMOUNT OF ATMOSPHERIC
MOISTURE WILL ACCOMPANY THE SYSTEM. BECAUSE OF THIS...IT APPEARS
LIKELY THAT PERIODS OF HEAVY RAINFALL WILL OCCUR ACROSS CENTRAL
ILLINOIS AND PORTIONS OF NORTHWESTERN INDIANA ON SATURDAY THROUGH
SUNDAY. THE LATEST FORECASTED TOTAL RAINFALL AMOUNTS CALLS FOR
BETWEEN THREE TO SIX INCHES ACROSS THE FAR SOUTHERN COUNTIES OF THE
CWA...LIVINGSTON/FORD/IROQUOIS/BENTON...WITH AMOUNTS DROPPING OFF
RAPIDLY TO THE NORTH. IT IS POSSIBLE THAT LOCATIONS NEAR THE
WISCONSIN BORDER MAY SEE VERY LITTLE RAINFALL.
THE RIVER BASINS MOSTLY LIKELY TO SEE THE GREATEST IMPACT WILL BE
THE KANKAKEE...IROQUOIS AND VERMILLION RIVERS AND SMALLER RIVERS
AND CREEKS DRAINING INTO THEM. GIVEN THE SLOW MOVEMENT TO THE
SYSTEM AND THE COPIOUS AMOUNTS OF DEEP LAYER MOISTURE LIKELY TO BE
PRESENT...WIDESPREAD RAINFALL AMOUNTS OF 2 INCHES PER SIX HOUR
PERIOD IS POSSIBLE...AND LOCALLY HIGHER AMOUNTS ARE CERTAINLY NOT
OUT OF THE QUESTION. THIS AREA WILL NEED TO BE UNDER CONSIDERATION
FOR AN AREAL FLOOD WARNING
FOR LOCATIONS NORTH OF THE HEAVY RAINFALL AXIS...NORTHWARD TO THE
I-88 CORRIDOR...1 TO 2 INCHES OF TOTAL RAINFALL IS POSSIBLE AND
THE MORE FLASHY BASINS OF THE SOUTHERN PORTIONS OF THE CHICAGO
METRO AREA COULD SEE FLOODING PROBLEMS AS WELL.
KREIN/KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
*MARGINAL GUSTINESS AS BOUNDARY LAYER DEEPENS WITH HEATING...
MIXING DOWN 15-20 KT TO THE SURFACE.
* TIMING WIND SHIFT FROM WSW TO NE WITH COLD FRONT SINKING FROM N
CENTRAL AND SW WI DOWN ACROSS AREA TOWARD EVENING.
* SMALL POTENTIAL FOR SHRA/ISOLD TS FAR SOUTHERN WI INTO NE AND
FAR N CENTRAL IL BORDER MID-LATE AFTERNOON.
* POTENTIAL FOR SHOWERS ASSOCIATED WITH TD ISAAC MAINLY BEYOND
12Z SATURDAY.
RATZER
//DISCUSSION...UPDATED 14Z...
ONLY VERY MINOR TWEAKS MADE TO 14Z TAFOR. SSW-SW LOW LEVEL WINDS
ADVECTING MID-UPPER 60S SURFACE DEW POINTS OVER THE AREA AT MID
MORNING WITH UPPER 60-LOWER 70S ACROSS CENTRAL IL. WITH CONTINUED
HEATING DURING THE LATE MORNING THE LOW LEVEL MOISTURE ADVECTION
WILL BE OFFSET BY DEEPENING OF MIXING IN THE BOUNDARY LAYER.
EXPECT DEW POINTS TO BE IN THE MID-UPPER 60S DURING THE
AFTERNOON. THIS GIVES CONVECTIVE TEMPERATURES IN THE UPPER 80S
WHICH IS FORECAST TO REACH AROUND NOON. THOUGH NOT OPERATIONALLY
SIGNIFICANT DID INCLUDE A FORECAST STARTING AT 17Z INCLUDING
HIGHER BASED CU DEVELOPING.
MODELS SHOW LOW LEVEL CONVERGENCE ALONG THE WI COLD FRONT
DROPPING TOWARD THE IL BORDER THIS AFTERNOON...AS WELL AS IN NE
ALONG A LAKE BREEZE BOUNDARY PUSHING INLAND. FORECAST SOUNDINGS
FROM THE 12Z RUC13 SHOW MINIMAL CIN OVER CHI AREA DURING THE
LATER AFTERNOON ALONG WITH DECENT CAPE VALUES. LOW LEVEL WARMING
AND CONVERGENCE WOULD FAVOR ISOLD TO SCT TS DEVELOPMENT ALONG THE
COLD FRONT AND LAKE BREEZE MID-LATE AFTERNOON...WHILE SUBSIDENCE
INN THE MID AND UPPER LEVELS ON THE PERIPHERY OF ISSAC REMNANTS
SPREAD OVER THE LOCAL AREA. THIS WITH INCREASING CLOUDS CUTTING
SURFACE HEATING DURING THE LATER AFTERNOON WOULD DISCOURAGE AN TS
DEVELOPMENT. THREAT TOO LOW AT THIS TIME TO INCLUDE ANY MENTION
IN TAFOR THOUGH LOW COVERAGE NOT TS LATE AFTERNOON NOT TOTALLY
OUT OF THE QUESTION.
TRS
PREVIOUS DISCUSSION...UPDATED 12Z...
LITTLE CHANGE IN AVIATION FORECAST THINKING FROM 06Z ISSUANCE.
MAIN FOCUS REMAINS ON TIMING OF WEAK COLD FRONT AND WIND SHIFT
FROM WEST-SOUTHWEST TO NORTHEAST TOWARD EVENING...THEN INCREASING
HIGH CLOUDS THIS AFTERNOON AND EVENTUAL PRECIP POTENTIAL SATURDAY
AS THE REMAINS OF TROPICAL DEPRESSION ISAAC MOVE SLOWLY INTO
IL/IND.
THE COLD FRONT...WHICH WAS FROM EAST CENTRAL WI TO NORTH CENTRAL
IA AT 11Z...WILL CONTINUE TO MOVE SLOWLY SOUTH TOWARD THE
TERMINALS TODAY. VAD WIND PROFILES INDICATE THE PRESENCE OF A 35
KT SPEED MAX ABOVE THE BOUNDARY LAYER AT AROUND 1000 FT AGL THIS
MORNING WHICH WILL RESULT IN A PERIOD OF MARGINAL LLWS FOR THE
NEXT HOUR OR TWO UNTIL THE BOUNDARY LAYER BECOMES MORE DEEPLY
MIXED. WITH MIXING...SOUTHWEST WINDS WILL BECOME A BIT BREEZY BY
MID-MORNING WITH GUSTS APPROACHING 20 KTS. THE GRADIENT SHOULD
WEAKEN THIS AFTERNOON AS THE COLD FRONTAL TROUGH APPROACHES
HOWEVER...ALLOWING WINDS TO DECREASE A BIT. TIMING OF THE FRONTAL
PASSAGE AND A WIND SHIFT FROM WEST-SOUTHWEST TO NORTHEAST STILL
APPEARS TO BE ON TRACK FOR THE 23-01Z PERIOD ACROSS THE
TERMINALS...WITH WINDS REMAINING NORTHEAST AROUND 10 KTS
OVERNIGHT.
ATTENTION THEN TURNS TO THE REMAINS OF ISAAC...WHICH LIFT SLOWLY
ACROSS THE MISSOURI VALLEY TODAY...THEN DRIFT EAST ACROSS CENTRAL
IL/IND SAT. THIS SYSTEM SHOULD PRODUCE JUST INCREASING HIGH/MID
CLOUDS ACROSS THE AREA LATER TODAY AND TONIGHT...WITH GUIDANCE
INDICATING RAIN SHOWERS MOVING INTO THE TERMINALS GENERALLY AFTER
12Z SATURDAY MORNING. ALL MODELS INDICATE A SHARP NORTHERN CUTOFF
TO THE PRECIP...WITH THAT CUTOFF LIKELY SOMEWHERE OVER NORTHERN
IL. AT THIS DISTANCE HAVE INDICATED A VICINITY SHOWER MENTION FOR
ORD IN THE FINAL HOURS OF THE 30 HR FORECAST...WITH ROOM FOR
FURTHER DEFINITION IN SUBSEQUENT FORECASTS. WITH THE LOW PRESSURE
CENTER MOVING INTO IL...THE PRESSURE GRADIENT LOOKS TO TIGHTEN
ENOUGH FOR WINDS TO COME UP INTO THE 10-15 KT RANGE SATURDAY
MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN WIND TRENDS PRIOR TO WIND SHIFT TOWARD
EVENING.
* MEDIUM CONFIDENCE IN WIND SHIFT TIMING WITH COLD FRONT.
* MEDIUM CONFIDENCE IN SHOWERS REMAINING S OF ORD/MDW THROUGH 12Z
SAT.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...
SUNDAY...CHC OF RA/SHRA. MVFR/IFR POSSIBLE.
MONDAY...SLGT CHC SHRA/TSRA. MVFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC SHRA/TSRA. OTHERWISE VFR.
RATZER
&&
.MARINE...
246 AM CDT
MARINE FORECAST CONCERNS INCLUDE A PERIOD OF GUSTY SOUTHWEST WINDS
THIS MORNING AHEAD OF A COLD FRONT WHICH WILL SAG SOUTH ACROSS LAKE
MICHIGAN TODAY...AND A PERIOD OF MODEST EAST-NORTHEAST WINDS THIS
THE WEEKEND AS THE SURFACE LOW PRESSURE CIRCULATION ASSOCIATED WITH
TROPICAL DEPRESSION ISAAC MOVES SLOWLY SOUTH OF THE GREAT LAKES.
LOW PRESSURE WAS LOCATED OVER EASTERN QUEBEC EARLY THIS
MORNING...WITH A COLD FRONT TRAILING SOUTHWESTWARD ACROSS THE
NORTHERN LAKES AND INTO CENTRAL WISCONSIN. THIS COLD FRONT WILL
CONTINUE TO SAG SOUTH ACROSS LAKE MICHIGAN TODAY AS THE EASTERN
CANADIAN LOW CONTINUES TO MOVE AWAY. SOUTHWEST WINDS AHEAD OF THE
FRONT HAVE BEEN FAIRLY GUST PARTICULARLY OVER THE NORTHERN END OF
LAKE MICHIGAN...WITH SOME GUSTS AROUND 30 KTS NOTED ALONG THE
EASTERN SHORE NORTH OF MANISTEE AND AROUND CHARLEVOIX. THESE
STRONGER WINDS SHOULD DIMINISH THIS MORNING...AS THE LOW LEVEL JET
ASSOCIATED WITH A PASSING UPPER DISTURBANCE PULLS OF TO THE EAST.
WINDS WILL VEER TO THE NORTH BEHIND THE FRONT TODAY AND TO
NORTH-NORTHEAST TONIGHT...AS THE FRONT CONTINUES TO DRIFT TO THE
SOUTH AND HIGH PRESSURE SPREADS ACROSS THE NORTHERN LAKES. THE HIGH
WILL DRIFT SOUTHEAST ACROSS THE NORTHERN/EASTERN LAKES SATURDAY AND
SUNDAY...WHILE THE AREA OF SURFACE LOW PRESSURE FROM TROPICAL
DEPRESSION ISAAC SLOWLY LIFTS ACROSS THE LOWER MISSOURI VALLEY
THROUGH TONIGHT...THEN TURNS EAST AND DRIFTS ACROSS SOUTH CENTRAL
IL/IND AS IT FILLS DURING THE REMAINDER OF THE WEEKEND. FORECAST
MODEL GUIDANCE CONTINUES TO EXHIBIT DIFFERENCES IN THE EXACT AND
STRENGTH OF ISAAC DURING THIS PERIOD...THOUGH THE PASSAGE OF THIS
LOW SOUTH OF THE LAKES SHOULD RESULT IN A PERIOD OF ENHANCED
EASTERLY FLOW PARTICULARLY ON THE SOUTHERN HALF OF LAKE MICHIGAN
ESPECIALLY LATE TONIGHT INTO SUNDAY. EAST WINDS TOPPING OUT IN THE
20-25 KT RANGE DURING THIS PERIOD MAY NECESSITATE SMALL CRAFT
ADVISORIES ALONG THE WESTERN SHORE OF SOUTHERN LAKE MICHIGAN OVER
THE WEEKEND...BEFORE THE LOW WEAKENS AND LOOSENS THE GRADIENT ACROSS
THE LAKE BY MONDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1245 PM EDT FRI AUG 31 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 234 AM EDT FRI AUG 31 2012
THE REMNANTS OF HURRICANE ISAAC WILL BE THE MAIN WEATHER FEATURE
OVER THE NEXT SEVERAL DAYS. HIGH CLOUDS ARE EXPECTED TO ARRIVE
TODAY AS THE REMNANTS MOVE FROM ARKANSAS INTO SOUTHERN MISSOURI.
RAIN SHOWERS...ALONG WITH SOME HEAVY RAIN IS EXPECTED TO ARRIVE ON
SATURDAY AFTERNOON AND SUNDAY AS THE REMNANTS BEGIN TO PUSH
NORTHEAST INTO ILLINOIS.
SCATTERED RAIN SHOWERS ARE EXPECTED TO LINGER ACROSS CENTRAL
INDIANA ON MONDAY AS THE REMNANTS SLOWLY WEAKEN AND SLOWLY
MEANDER EASTWARD INTO THE OHIO VALLEY.
AS THE REMNANTS DEPART AS LOW PRESSURE ON TUESDAY NIGHT...HIGH
PRESSURE WILL BUILD ACROSS INDIANA BRINGING DRY WEATHER FOR THE
MIDDLE OF THE NEXT WORK WEEK. ANOTHER COLD FRONT WILL APPROACH OUR
REGION THURSDAY AS A STRONG UPPER TROUGH DIGS INTO THE UPPER
MIDWEST.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1020 AM AM EDT FRI AUG 31 2012
VISIBLE SATELLITE SHOWS AN EXTENSIVE AREA OF MID CLOUDS WERE
SPREADING NORTHEAST ACROSS OUR REGION. SOME OF THIS MAY THIN OUT
THIS AFTERNOON...SO WILL GO PARTLY CLOUDY MOST SECTIONS TODAY.
THE BIGGEST QUESTION WILL BE WHAT TO DO WITH TEMPERATURES. BOTH THE
NAM AND 12Z RUC STILL INDICATE TEMPERATURES IN THE LOWER 90S THIS
AFTERNOON. THIS SEEMS A BIT WARM GIVEN THAT THEY WERE SEVERAL
DEGREES TOO WARM YESTERDAY WITH FULL SUNSHINE. WILL RAISE
TEMPERATURES JUST A TAD TODAY GIVEN THAT CLOUDS MAY THIN OUT AND
MODELS ARE RUNNING SO WARM.
IN REGARDS TO PRECIP RADAR SHOWS A BAND OF MOSTLY VIRGA SPREADING
NORTH ACROSS OUR STATE. RAPID REFRESH SHOWS A 2ND BAND OF SHOWERS
AND THUNDERSTORMS WILL BE ALONG OUR WESTERN BORDER BY LATE
AFTERNOON. WILL RAISE POPS A LITTLE ALONG OUR WEST AND ADD SLIGHT
CHANCE POPS OVER MOST OF OUR FAR SOUTH THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 234 AM EDT FRI AUG 31 2012
MODELS ARE PRETTY CLOSE WITH THE HANDLING OF THE REMNANTS...BUT AS
WE APPROACH SUNDAY AFTERNOON THE NAM SOLUTION OF KEEPING THE LOW
CENTERED OVER MISSOURI DOESN/T MAKE MUCH SENSE...AS WELL AS THE
LACK OF EASTERN PROPAGATION. THUS WILL USE A BLEND INITIALLY BUT
TREND TOWARD THE GFS BY SUNDAY AND SUNDAY NIGHT.
TWO FEATURES ARE GOING TO COME TOGETHER TO HELP PRODUCE RAIN
ACROSS CENTRAL INDIANA THIS PERIOD. THE APPROACHING REMNANTS OF
ISAAC COMBINING WITH A FRONTAL BOUNDARY OVER THE UPPER MIDWEST
WHICH IS EXPECTED TO SAG SOUTHWARD AND HELP PROVIDE AN EXTRA LIFT
MECHANISM ON SATURDAY AND SUNDAY.
CLOUDS WILL BE EXPECTED TO INCREASE BY TONIGHT AND A FEW SHOWERS
COULD REACH THE AREA AS BANDS OF PRECIP CONTINUE TO SWIRL AROUND
THE LOW WHICH IS EXPECTED TO DRIFT INTO MISSOURI. GIVEN THE
CURRENT STRUCTURE OF THE SYSTEM...AND AS DRY AIR CONTINUES TO
INFILTRATE THE SYSTEM AS IT APPROACHES...A FEW SHOWERS CANNOT BE
RULED OUT REACHING CENTRAL INDIANA OVERNIGHT...PARTICULARLY
ACROSS THE WEST WHERE PROXIMITY IS BEST. WILL KEEP SOME PRECIP
CHANCES FOR TONIGHT IN TO FORECAST PARTICULAR ACROSS THE WEST.
WITH THE ARRIVAL OF A VERY MOIST AIR MASS WILL TREND LOWS HIGHER
THAN MAVMOS.
AS THE FRONTAL BOUNDARY SAGS SOUTHWARD AND BEGINS TO INTERACT WITH
THE REMNANTS OF ISAAC ON SATURDAY AFTERNOON...MORE WIDESPREAD RAIN
SHOWERS ARE EXPECTED TO DEVELOP. LOW LEVEL Q VECTORS DISPLAY
STRONG CONVERGENCE ACROSS THE AREA BY SATURDAY AFTERNOON AND
EVENING AS FORECAST SOUNDINGS REVEAL DEEP MOISTURE PRESENT. WILL
STICK WITH NEAR CATEGORICAL POPS FOR SATURDAY...WITH BEST CHANCES
STARTING THIS AFTERNOON...ALTHOUGH CONFIDENCE REGARDING PRECISE
TIMING ON THE START OF RAINFALL REMAINS LOW DUE TO THE SLOW
ARRIVAL OF THE APPROACHING SYSTEM. WILL ALSO TREND HIGH TEMPS
COOLER THAN MAVMOS.
GFS AND NAM Q VECTORS CONTINUE TO SUGGEST STRONG LOWER LEVEL
CONVERGENCE ON SATURDAY NIGHT AND ON SUNDAY AND THE FRONTAL
BOUNDARY FROM THE NORTH STALLS OVER THE REGION. FORECAST SOUNDINGS
CONTINUE TO SHOW DEEP MOISTURE AVAILABLE WITH THE LINGERING
TROPICAL REMNANTS. WILL CONTINUE TO KEEP HIGH POPS ONGOING ON
SATURDAY AND SUNDAY...WITH LOW TEMPS WARMER THAN GUIDANCE AND HIGH
TEMPS COOLER DUE TO EXPECTED CLOUDS AND RAIN. LOWER LEVEL PRESSURE
GRADIENT APPEARS TO GET WEAKER AS THE SYSTEM ARRIVES...AND
ALTHOUGH SOME GUSTY WINDS CANNOT BE RULED OUT...ANY GUSTS SHOULD
BE LESS THAN PREVIOUSLY EXPECTED.
WITH THE SLOW PROGRESSION OF THE SYSTEM...AS THE GFS DEPICTS THE
LOW PRESSURE CENTER ONLY REACHING WESTERN INDIANA BY SUNDAY NIGHT
WILL NEED TO CONTINUE WITH SOME POPS ON SUNDAY NIGHT. ALTHOUGH
BEST FORCING WILL REMAIN WELL SOUTHEAST OF THE LOW...OVER
SOUTHEAST INDIANA AND KENTUCKY AS THE FRONTAL BOUNDARY IS EXPECTED
TO SAG SOUTHWARD TOWARD THE OHIO RIVER THEN. FORECAST SOUNDINGS
CONTINUE TO INDICATE DEEP MOISTURE AVAILABLE...BUT WITH MORE
LIMITED FORCING. WILL TREND LOWS WARMER THAN GUIDANCE GIVEN THE
CLOUDS AND MOIST...TROPICAL AIR MASS THAT WILL BE PLACE.
SUMMING UP...BEST CHANCES FOR HEAVY RAINS CONTINUE TO APPEAR TO BE
SATURDAY THROUGH SUNDAY...AND THIS PERIOD WILL ALSO BE THE PERIOD
THAT HAS THE BEST CHANCES FOR FLOODING.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 234 AM EDT FRI AUG 31 2012
ENSEMBLE DATA INDICATE REMNANTS OF TROPICAL CYCLONE ISAAC MAY STILL
BE IN THE PROCESS OF PASSING ACROSS THE AREA ON MONDAY.
OTHERWISE...THE DATA INDICATE THE JET STREAM WILL BE GRADUALLY
SINKING SOUTH WITH TIME AS A SERIES OF DISTURBANCES MOVE EAST
SOUTHEAST ACROSS THE UPPER GREAT LAKES.
LOOKS LIKE A RATHER UNSETTLED EXTENDED PERIOD...WITH THE POTENTIAL
FOR A COUPLE OF FRONTAL PASSAGES IN ADDITION TO WHAT IS LEFT OF
ISAAC. AT THIS POINT...THE ENSEMBLES SUGGEST A PRECIPITATION THREAT
PRETTY MUCH EVERY DAY EXCEPT FOR THE TUESDAY NIGHT AND WEDNESDAY
TIME FRAME. WILL GO WITH POPS ON MONDAY...TUESDAY...AND
THURSDAY...AND KEEP WEDNESDAY DRY.
&&
.AVIATION /DISCUSSION FOR THE 311800Z TAFS/...
ISSUED AT 1245 PM EDT FRI AUG 31 2012
CONDITIONS WILL DETERIORATE TO MVFR TONIGHT AND REMAIN SO FOR MUCH
OF SATURDAY.
CONFIDENCE IS BELOW AVERAGE WITH FORECAST DUE TO CONTINUING
UNCERTAINTY IN TIMING AND PATH OF ISAAC REMNANTS AND UNCERTAINTIES
IN WHERE HEAVIER RAIN WILL DEVELOP.
THROUGH 00Z OR SO ONLY EXPECT SCATTERED LOW CLOUDS AND BROKEN MID
CLOUDS. THERE WILL BE SOME LIGHT SHOWER ACTIVITY...BUT MOST OF THE
SHOWERS WILL BE CONFINED TO AREAS NEAR KHUF AND KLAF. VISIBILITIES
WILL BE MAINLY VFR IN THE SHOWERS...BUT BRIEF MVFR IS NOT OUT OF THE
QUESTION.
OTHERWISE EXPECT MVFR CLOUDS TO MOVE IN OVERNIGHT AS MOISTURE
CONTINUES TO INCREASE AHEAD OF REMNANTS OF ISAAC. RAIN WILL
GRADUALLY BECOME MORE WIDESPREAD...ESPECIALLY ACROSS THE WESTERN
SITES. HEAVIER RAIN SHOULDN/T ARRIVE UNTIL AFTER THE TAF PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...JH
SHORT TERM...PUMA
LONG TERM....JAS
AVIATION...50
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1030 AM EDT FRI AUG 31 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 234 AM EDT FRI AUG 31 2012
THE REMNANTS OF HURRICANE ISAAC WILL BE THE MAIN WEATHER FEATURE
OVER THE NEXT SEVERAL DAYS. HIGH CLOUDS ARE EXPECTED TO ARRIVE
TODAY AS THE REMNANTS MOVE FROM ARKANSAS INTO SOUTHERN MISSOURI.
RAIN SHOWERS...ALONG WITH SOME HEAVY RAIN IS EXPECTED TO ARRIVE ON
SATURDAY AFTERNOON AND SUNDAY AS THE REMNANTS BEGIN TO PUSH
NORTHEAST INTO ILLINOIS.
SCATTERED RAIN SHOWERS ARE EXPECTED TO LINGER ACROSS CENTRAL
INDIANA ON MONDAY AS THE REMNANTS SLOWLY WEAKEN AND SLOWLY
MEANDER EASTWARD INTO THE OHIO VALLEY.
AS THE REMNANTS DEPART AS LOW PRESSURE ON TUESDAY NIGHT...HIGH
PRESSURE WILL BUILD ACROSS INDIANA BRINGING DRY WEATHER FOR THE
MIDDLE OF THE NEXT WORK WEEK. ANOTHER COLD FRONT WILL APPROACH OUR
REGION THURSDAY AS A STRONG UPPER TROUGH DIGS INTO THE UPPER
MIDWEST.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1020 AM AM EDT FRI AUG 31 2012
VISIBLE SATELLITE SHOWS AN EXTENSIVE AREA OF MID CLOUDS WERE
SPREADING NORTHEAST ACROSS OUR REGION. SOME OF THIS MAY THIN OUT
THIS AFTERNOON...SO WILL GO PARTLY CLOUDY MOST SECTIONS TODAY.
THE BIGGEST QUESTION WILL BE WHAT TO DO WITH TEMPERATURES. BOTH THE
NAM AND 12Z RUC STILL INDICATE TEMPERATURES IN THE LOWER 90S THIS
AFTERNOON. THIS SEEMS A BIT WARM GIVEN THAT THEY WERE SEVERAL
DEGREES TOO WARM YESTERDAY WITH FULL SUNSHINE. WILL RAISE
TEMPERATURES JUST A TAD TODAY GIVEN THAT CLOUDS MAY THIN OUT AND
MODELS ARE RUNNING SO WARM.
IN REGARDS TO PRECIP RADAR SHOWS A BAND OF MOSTLY VIRGA SPREADING
NORTH ACROSS OUR STATE. RAPID REFRESH SHOWS A 2ND BAND OF SHOWERS
AND THUNDERSTORMS WILL BE ALONG OUR WESTERN BORDER BY LATE
AFTERNOON. WILL RAISE POPS A LITTLE ALONG OUR WEST AND ADD SLIGHT
CHANCE POPS OVER MOST OF OUR FAR SOUTH THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 234 AM EDT FRI AUG 31 2012
MODELS ARE PRETTY CLOSE WITH THE HANDLING OF THE REMNANTS...BUT AS
WE APPROACH SUNDAY AFTERNOON THE NAM SOLUTION OF KEEPING THE LOW
CENTERED OVER MISSOURI DOESN/T MAKE MUCH SENSE...AS WELL AS THE
LACK OF EASTERN PROPAGATION. THUS WILL USE A BLEND INITIALLY BUT
TREND TOWARD THE GFS BY SUNDAY AND SUNDAY NIGHT.
TWO FEATURES ARE GOING TO COME TOGETHER TO HELP PRODUCE RAIN
ACROSS CENTRAL INDIANA THIS PERIOD. THE APPROACHING REMNANTS OF
ISAAC COMBINING WITH A FRONTAL BOUNDARY OVER THE UPPER MIDWEST
WHICH IS EXPECTED TO SAG SOUTHWARD AND HELP PROVIDE AN EXTRA LIFT
MECHANISM ON SATURDAY AND SUNDAY.
CLOUDS WILL BE EXPECTED TO INCREASE BY TONIGHT AND A FEW SHOWERS
COULD REACH THE AREA AS BANDS OF PRECIP CONTINUE TO SWIRL AROUND
THE LOW WHICH IS EXPECTED TO DRIFT INTO MISSOURI. GIVEN THE
CURRENT STRUCTURE OF THE SYSTEM...AND AS DRY AIR CONTINUES TO
INFILTRATE THE SYSTEM AS IT APPROACHES...A FEW SHOWERS CANNOT BE
RULED OUT REACHING CENTRAL INDIANA OVERNIGHT...PARTICULARLY
ACROSS THE WEST WHERE PROXIMITY IS BEST. WILL KEEP SOME PRECIP
CHANCES FOR TONIGHT IN TO FORECAST PARTICULAR ACROSS THE WEST.
WITH THE ARRIVAL OF A VERY MOIST AIR MASS WILL TREND LOWS HIGHER
THAN MAVMOS.
AS THE FRONTAL BOUNDARY SAGS SOUTHWARD AND BEGINS TO INTERACT WITH
THE REMNANTS OF ISAAC ON SATURDAY AFTERNOON...MORE WIDESPREAD RAIN
SHOWERS ARE EXPECTED TO DEVELOP. LOW LEVEL Q VECTORS DISPLAY
STRONG CONVERGENCE ACROSS THE AREA BY SATURDAY AFTERNOON AND
EVENING AS FORECAST SOUNDINGS REVEAL DEEP MOISTURE PRESENT. WILL
STICK WITH NEAR CATEGORICAL POPS FOR SATURDAY...WITH BEST CHANCES
STARTING THIS AFTERNOON...ALTHOUGH CONFIDENCE REGARDING PRECISE
TIMING ON THE START OF RAINFALL REMAINS LOW DUE TO THE SLOW
ARRIVAL OF THE APPROACHING SYSTEM. WILL ALSO TREND HIGH TEMPS
COOLER THAN MAVMOS.
GFS AND NAM Q VECTORS CONTINUE TO SUGGEST STRONG LOWER LEVEL
CONVERGENCE ON SATURDAY NIGHT AND ON SUNDAY AND THE FRONTAL
BOUNDARY FROM THE NORTH STALLS OVER THE REGION. FORECAST SOUNDINGS
CONTINUE TO SHOW DEEP MOISTURE AVAILABLE WITH THE LINGERING
TROPICAL REMNANTS. WILL CONTINUE TO KEEP HIGH POPS ONGOING ON
SATURDAY AND SUNDAY...WITH LOW TEMPS WARMER THAN GUIDANCE AND HIGH
TEMPS COOLER DUE TO EXPECTED CLOUDS AND RAIN. LOWER LEVEL PRESSURE
GRADIENT APPEARS TO GET WEAKER AS THE SYSTEM ARRIVES...AND
ALTHOUGH SOME GUSTY WINDS CANNOT BE RULED OUT...ANY GUSTS SHOULD
BE LESS THAN PREVIOUSLY EXPECTED.
WITH THE SLOW PROGRESSION OF THE SYSTEM...AS THE GFS DEPICTS THE
LOW PRESSURE CENTER ONLY REACHING WESTERN INDIANA BY SUNDAY NIGHT
WILL NEED TO CONTINUE WITH SOME POPS ON SUNDAY NIGHT. ALTHOUGH
BEST FORCING WILL REMAIN WELL SOUTHEAST OF THE LOW...OVER
SOUTHEAST INDIANA AND KENTUCKY AS THE FRONTAL BOUNDARY IS EXPECTED
TO SAG SOUTHWARD TOWARD THE OHIO RIVER THEN. FORECAST SOUNDINGS
CONTINUE TO INDICATE DEEP MOISTURE AVAILABLE...BUT WITH MORE
LIMITED FORCING. WILL TREND LOWS WARMER THAN GUIDANCE GIVEN THE
CLOUDS AND MOIST...TROPICAL AIR MASS THAT WILL BE PLACE.
SUMMING UP...BEST CHANCES FOR HEAVY RAINS CONTINUE TO APPEAR TO BE
SATURDAY THROUGH SUNDAY...AND THIS PERIOD WILL ALSO BE THE PERIOD
THAT HAS THE BEST CHANCES FOR FLOODING.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 234 AM EDT FRI AUG 31 2012
ENSEMBLE DATA INDICATE REMNANTS OF TROPICAL CYCLONE ISAAC MAY STILL
BE IN THE PROCESS OF PASSING ACROSS THE AREA ON MONDAY.
OTHERWISE...THE DATA INDICATE THE JET STREAM WILL BE GRADUALLY
SINKING SOUTH WITH TIME AS A SERIES OF DISTURBANCES MOVE EAST
SOUTHEAST ACROSS THE UPPER GREAT LAKES.
LOOKS LIKE A RATHER UNSETTLED EXTENDED PERIOD...WITH THE POTENTIAL
FOR A COUPLE OF FRONTAL PASSAGES IN ADDITION TO WHAT IS LEFT OF
ISAAC. AT THIS POINT...THE ENSEMBLES SUGGEST A PRECIPITATION THREAT
PRETTY MUCH EVERY DAY EXCEPT FOR THE TUESDAY NIGHT AND WEDNESDAY
TIME FRAME. WILL GO WITH POPS ON MONDAY...TUESDAY...AND
THURSDAY...AND KEEP WEDNESDAY DRY.
&&
.AVIATION /DISCUSSION FOR THE 311430Z TAF UPDATE/...
ISSUED AT 1030 AM EDT FRI AUG 31 2012
KIND TAF LOOKS GOOD. ONLY MINOR CHANGE TO WIND DIRECTION MADE. THERE
COULD BE SOME SPRINKLES/LIGHT SHOWERS BY AFTERNOON...BUT THESE WILL
NOT LOWER VISIBILITY BELOW VFR.
PREVIOUS DISCUSSION FOLLOWS...
CLOUD COVER WILL BE INCREASING TODAY...BUT CEILINGS SHOULD REMAIN
WELL ABOVE 050 THROUGH 010000Z. SOME DIURNAL CLOUD COVER BASED
AROUND 030 POSSIBLE AFTER 311500Z.
SOME LOW POTENTIAL FOR WIDELY SCATTERED CONVECTION BY THE MID
AFTERNOON HOURS...ESPECIALLY OVER THE MORE SOUTHERN TAF SITES...AS A
VORTICITY LOBE SWINGS INTO THE AREA FROM THE SOUTH AND CONVECTIVE
TEMPERATURES ARE WITHIN REACH. HOWEVER...CHANCES FOR A DIRECT IMPACT
AT A PARTICULAR TAF SITE TOO LOW TO MENTION AT THIS POINT.
NO PROLONGED VISIBILITY RESTRICTIONS...SURFACE WINDS GENERALLY UNDER
12 KTS THROUGH 010000Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...JH
SHORT TERM...PUMA
LONG TERM....JAS
AVIATION...JAS/50
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1020 AM EDT FRI AUG 31 2012
.UPDATE...
NEAR TERM SECTION FOR THE REST OF TODAY HAS BEEN UDPATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 234 AM EDT FRI AUG 31 2012
THE REMNANTS OF HURRICANE ISAAC WILL BE THE MAIN WEATHER FEATURE
OVER THE NEXT SEVERAL DAYS. HIGH CLOUDS ARE EXPECTED TO ARRIVE
TODAY AS THE REMNANTS MOVE FROM ARKANSAS INTO SOUTHERN MISSOURI.
RAIN SHOWERS...ALONG WITH SOME HEAVY RAIN IS EXPECTED TO ARRIVE ON
SATURDAY AFTERNOON AND SUNDAY AS THE REMNANTS BEGIN TO PUSH
NORTHEAST INTO ILLINOIS.
SCATTERED RAIN SHOWERS ARE EXPECTED TO LINGER ACROSS CENTRAL
INDIANA ON MONDAY AS THE REMNANTS SLOWLY WEAKEN AND SLOWLY
MEANDER EASTWARD INTO THE OHIO VALLEY.
AS THE REMNANTS DEPART AS LOW PRESSURE ON TUESDAY NIGHT...HIGH
PRESSURE WILL BUILD ACROSS INDIANA BRINGING DRY WEATHER FOR THE
MIDDLE OF THE NEXT WORK WEEK. ANOTHER COLD FRONT WILL APPROACH OUR
REGION THURSDAY AS A STRONG UPPER TROUGH DIGS INTO THE UPPER
MIDWEST.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1020 AM AM EDT FRI AUG 31 2012
VISIBLE SATELLITE SHOWS AN EXTENSIVE AREA OF MID CLOUDS WERE
SPREADING NORTHEAST ACROSS OUR REGION. SOME OF THIS MAY THIN OUT
THIS AFTERNOON...SO WILL GO PARTLY CLOUDY MOST SECTIONS TODAY.
THE BIGGEST QUESTION WILL BE WHAT TO DO WITH TEMPERATURES. BOTH THE
NAM AND 12Z RUC STILL INDICATE TEMPERATURES IN THE LOWER 90S THIS
AFTERNOON. THIS SEEMS A BIT WARM GIVEN THAT THEY WERE SEVERAL
DEGREES TOO WARM YESTERDAY WITH FULL SUNSHINE. WILL RAISE
TEMPERATURES JUST A TAD TODAY GIVEN THAT CLOUDS MAY THIN OUT AND
MODELS ARE RUNNING SO WARM.
IN REGARDS TO PRECIP RADAR SHOWS A BAND OF MOSTLY VIRGA SPREADING
NORTH ACROSS OUR STATE. RAPID REFRESH SHOWS A 2ND BAND OF SHOWERS
AND THUNDERSTORMS WILL BE ALONG OUR WESTERN BORDER BY LATE
AFTERNOON. WILL RAISE POPS A LITTLE ALONG OUR WEST AND ADD SLIGHT
CHANCE POPS OVER MOST OF OUR FAR SOUTH THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 234 AM EDT FRI AUG 31 2012
MODELS ARE PRETTY CLOSE WITH THE HANDLING OF THE REMNANTS...BUT AS
WE APPROACH SUNDAY AFTERNOON THE NAM SOLUTION OF KEEPING THE LOW
CENTERED OVER MISSOURI DOESN/T MAKE MUCH SENSE...AS WELL AS THE
LACK OF EASTERN PROPAGATION. THUS WILL USE A BLEND INITIALLY BUT
TREND TOWARD THE GFS BY SUNDAY AND SUNDAY NIGHT.
TWO FEATURES ARE GOING TO COME TOGETHER TO HELP PRODUCE RAIN
ACROSS CENTRAL INDIANA THIS PERIOD. THE APPROACHING REMNANTS OF
ISAAC COMBINING WITH A FRONTAL BOUNDARY OVER THE UPPER MIDWEST
WHICH IS EXPECTED TO SAG SOUTHWARD AND HELP PROVIDE AN EXTRA LIFT
MECHANISM ON SATURDAY AND SUNDAY.
CLOUDS WILL BE EXPECTED TO INCREASE BY TONIGHT AND A FEW SHOWERS
COULD REACH THE AREA AS BANDS OF PRECIP CONTINUE TO SWIRL AROUND
THE LOW WHICH IS EXPECTED TO DRIFT INTO MISSOURI. GIVEN THE
CURRENT STRUCTURE OF THE SYSTEM...AND AS DRY AIR CONTINUES TO
INFILTRATE THE SYSTEM AS IT APPROACHES...A FEW SHOWERS CANNOT BE
RULED OUT REACHING CENTRAL INDIANA OVERNIGHT...PARTICULARLY
ACROSS THE WEST WHERE PROXIMITY IS BEST. WILL KEEP SOME PRECIP
CHANCES FOR TONIGHT IN TO FORECAST PARTICULAR ACROSS THE WEST.
WITH THE ARRIVAL OF A VERY MOIST AIR MASS WILL TREND LOWS HIGHER
THAN MAVMOS.
AS THE FRONTAL BOUNDARY SAGS SOUTHWARD AND BEGINS TO INTERACT WITH
THE REMNANTS OF ISAAC ON SATURDAY AFTERNOON...MORE WIDESPREAD RAIN
SHOWERS ARE EXPECTED TO DEVELOP. LOW LEVEL Q VECTORS DISPLAY
STRONG CONVERGENCE ACROSS THE AREA BY SATURDAY AFTERNOON AND
EVENING AS FORECAST SOUNDINGS REVEAL DEEP MOISTURE PRESENT. WILL
STICK WITH NEAR CATEGORICAL POPS FOR SATURDAY...WITH BEST CHANCES
STARTING THIS AFTERNOON...ALTHOUGH CONFIDENCE REGARDING PRECISE
TIMING ON THE START OF RAINFALL REMAINS LOW DUE TO THE SLOW
ARRIVAL OF THE APPROACHING SYSTEM. WILL ALSO TREND HIGH TEMPS
COOLER THAN MAVMOS.
GFS AND NAM Q VECTORS CONTINUE TO SUGGEST STRONG LOWER LEVEL
CONVERGENCE ON SATURDAY NIGHT AND ON SUNDAY AND THE FRONTAL
BOUNDARY FROM THE NORTH STALLS OVER THE REGION. FORECAST SOUNDINGS
CONTINUE TO SHOW DEEP MOISTURE AVAILABLE WITH THE LINGERING
TROPICAL REMNANTS. WILL CONTINUE TO KEEP HIGH POPS ONGOING ON
SATURDAY AND SUNDAY...WITH LOW TEMPS WARMER THAN GUIDANCE AND HIGH
TEMPS COOLER DUE TO EXPECTED CLOUDS AND RAIN. LOWER LEVEL PRESSURE
GRADIENT APPEARS TO GET WEAKER AS THE SYSTEM ARRIVES...AND
ALTHOUGH SOME GUSTY WINDS CANNOT BE RULED OUT...ANY GUSTS SHOULD
BE LESS THAN PREVIOUSLY EXPECTED.
WITH THE SLOW PROGRESSION OF THE SYSTEM...AS THE GFS DEPICTS THE
LOW PRESSURE CENTER ONLY REACHING WESTERN INDIANA BY SUNDAY NIGHT
WILL NEED TO CONTINUE WITH SOME POPS ON SUNDAY NIGHT. ALTHOUGH
BEST FORCING WILL REMAIN WELL SOUTHEAST OF THE LOW...OVER
SOUTHEAST INDIANA AND KENTUCKY AS THE FRONTAL BOUNDARY IS EXPECTED
TO SAG SOUTHWARD TOWARD THE OHIO RIVER THEN. FORECAST SOUNDINGS
CONTINUE TO INDICATE DEEP MOISTURE AVAILABLE...BUT WITH MORE
LIMITED FORCING. WILL TREND LOWS WARMER THAN GUIDANCE GIVEN THE
CLOUDS AND MOIST...TROPICAL AIR MASS THAT WILL BE PLACE.
SUMMING UP...BEST CHANCES FOR HEAVY RAINS CONTINUE TO APPEAR TO BE
SATURDAY THROUGH SUNDAY...AND THIS PERIOD WILL ALSO BE THE PERIOD
THAT HAS THE BEST CHANCES FOR FLOODING.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 234 AM EDT FRI AUG 31 2012
ENSEMBLE DATA INDICATE REMNANTS OF TROPICAL CYCLONE ISAAC MAY STILL
BE IN THE PROCESS OF PASSING ACROSS THE AREA ON MONDAY.
OTHERWISE...THE DATA INDICATE THE JET STREAM WILL BE GRADUALLY
SINKING SOUTH WITH TIME AS A SERIES OF DISTURBANCES MOVE EAST
SOUTHEAST ACROSS THE UPPER GREAT LAKES.
LOOKS LIKE A RATHER UNSETTLED EXTENDED PERIOD...WITH THE POTENTIAL
FOR A COUPLE OF FRONTAL PASSAGES IN ADDITION TO WHAT IS LEFT OF
ISAAC. AT THIS POINT...THE ENSEMBLES SUGGEST A PRECIPITATION THREAT
PRETTY MUCH EVERY DAY EXCEPT FOR THE TUESDAY NIGHT AND WEDNESDAY
TIME FRAME. WILL GO WITH POPS ON MONDAY...TUESDAY...AND
THURSDAY...AND KEEP WEDNESDAY DRY.
&&
.AVIATION /DISCUSSION FOR THE 311200Z TAFS/...
ISSUED AT 632 AM EDT FRI AUG 31 2012
CLOUD COVER WILL BE INCREASING TODAY...BUT CEILINGS SHOULD REMAIN
WELL ABOVE 050 THROUGH 010000Z. SOME DIURNAL CLOUD COVER BASED
AROUND 030 POSSIBLE AFTER 311500Z.
SOME LOW POTENTIAL FOR WIDELY SCATTERED CONVECTION BY THE MID
AFTERNOON HOURS...ESPECIALLY OVER THE MORE SOUTHERN TAF SITES...AS A
VORTICITY LOBE SWINGS INTO THE AREA FROM THE SOUTH AND CONVECTIVE
TEMPERATURES ARE WITHIN REACH. HOWEVER...CHANCES FOR A DIRECT IMPACT
AT A PARTICULAR TAF SITE TOO LOW TO MENTION AT THIS POINT.
NO PROLONGED VISIBILITY RESTRICTIONS...SURFACE WINDS GENERALLY UNDER
12 KTS THROUGH 010000Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...JH
SHORT TERM...PUMA
LONG TERM....JAS
AVIATION...JAS
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
225 PM EDT THU AUG 30 2012
.UPDATE...
ISSUED AT 225 PM EDT THU AUG 30 2012
DID AN UPDATE TO THE GRIDS TO INCREASE THE DEWPOINTS...SKY COVER AND
POPS IN THE SOUTH AS THE TROPICAL MOISTURE IS STARTING TO SEEP IN AND
PROMOTE THE START OF CONVECTION. THE LATEST HRRR SUPPORTS THIS IDEA
AS WELL. ACCORDINGLY...AN UPDATE TO THE GRIDS...WEB PAGES...AND
ZONES IS FORTHCOMING.
UPDATE ISSUED AT 955 AM EDT THU AUG 30 2012
13Z SFC ANALYSIS SHOWS HIGH PRESSURE OFF TO THE NORTHEAST OF
KENTUCKY...BUT STILL EXERTING ENOUGH INFLUENCE TO KEEP THE CLOUDS AND
WEATHER AT BAY FOR ONE MORE DAY. THIS IS BEING STARKLY DEMONSTRATED
ON SATELLITE CURRENTLY AS THE LEADING HIGH CLOUDS FROM ISAAC HAVE
SEEMINGLY HIT A WALL RIGHT ALONG OUR BORDER WITH TENNESSEE. THE
EARLIER PATCHY VALLEY FOG HAS LIFTED AND DISSIPATED THROUGH THE AREA
SO NOTHING STANDS IN THE WAY OF A SUNNY AND PLEASANT DAY FOR ALL BUT
PARTS OF OUR TENNESSEE BORDER COUNTIES. HAVE UPDATED THE GRIDS TO
REFLECT THE LATEST THOUGHTS ON SKY COVER THROUGH THE DAY AND FOR
ADJUSTMENTS TO THE T AND TD ONES BASED ON THE LATEST OBS AND TRENDS.
UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. HAVE ALSO UPDATED
THE ZONES...MAINLY TO REMOVE THE MENTION OF MORNING FOG.
UPDATE ISSUED AT 712 AM EDT THU AUG 30 2012
ISSUED A MORNING UPDATE TO FRESHEN UP THE GRIDS AND SEND THEM OFF TO
NDFD. SOME 5 TO 7 KFT CLOUD LAYERS HAVE EDGED INTO THE AREA SOUTH OF
THE HAL ROGERS PARKWAY SO UPDATED CLOUD COVER. OTHERWISE...FORECAST
IS ON TRACK AND A NEW ZFP WILL NOT BE NEEDED.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 345 AM EDT THU AUG 30 2012
MAIN CONCERNS DURING THE SHORT TERM WILL REVOLVE AROUND THE INITIAL
IMPACTS OF ISAAC INTO THE OHIO VALLEY. AS OF 07Z CLEAR SKIES RESIDE
OVER EASTERN KENTUCKY WITH CIRRUS ASSOCIATED WITH ISAAC SKIRTING THE
TN BORDER. OTHERWISE CLEAR SKIES HAS ALLOWED A DECENT RIDGE VALLEY
SPLIT ACROSS THE AREA AS WELL AS SOME VALLEY FOG...BUT CONFINED TO
THE DEEPER RIVER VALLEYS SO WILL MENTION THAT THIS MORNING.
AN INCREASE OF CLOUD COVER INTO THE AREA WILL KEEP MORNING LOWS IN
THE UPPER 60S AND LOW 70S ACROSS THE SOUTHERN CWA FOR TONIGHT AS
WELL AS LIMITING ANY FOG CHANCES.
FOR FRIDAY...WITH SHORT TERM MODEL TRENDS IN THE NAM AND GFS SHOWING
PRECIP MOVING INTO EASTERN KENTUCKY A BIT EARLIER...WILL ACCOUNT FOR
THE INCREASED CLOUD COVER AND LOWER HIGHS ON FRIDAY A FEW DEGREES
FROM TODAY AND BRING IN CLOUD COVER AND POPS A BIT FASTER. WILL
STICK TO SLIGHT AND LOW CHANCE AS CURRENT TRENDS OF ISAAC MIGHT NOT
GIVE THE FASTER APPROACH THAT THE MODELS PORTRAY.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 345 AM EDT THU AUG 30 2012
THE MODELS START OUT IN GOOD AGREEMENT THROUGH SUNDAY MORNING AS
THEY TRY TO PREDICT WHERE THE REMNANTS OF ISAAC WILL BE GOING. THE
PROBLEM IS THAT THE STORM WILL BE MOVING UP AGAINST A FAIRLY STRONG
AREA OF HIGH PRESSURE AND THE STEERING CURRENTS WILL BE FAIRLY WEAK.
THIS TYPE OF SITUATION TENDS TO CHALLENGING FOR THE MODELS TO HANDLE
AND EXPLAINS WHY THERE HAS BEEN SO MUCH RUN TO RUN INCONSISTENCIES
WITH THE MODELS. THE MODELS DO SEEM TO BE GETTING A BIT MORE
CONSISTENT...SO CONFIDENCE IS BEGINNING TO INCREASE. BY SUNDAY
MORNING THE UPPER LOW WILL BE OVER SOUTHERN ILLINOIS. THE ECMWF THEN
HAS THE LOW SLOW UP AND START TO DRIFT SLOW TO THE SOUTHWEST INTO
KENTUCKY. THE ECMWF THEN HAS THE LOW AND UPPER TROUGH LINGER OVER
KENTUCKY WHICH WILL HELP TO KEEP THE WEATHER UNSETTLED INTO
TUESDAY. THIS SHOULD HELP TO SPREAD SOME RAIN ACROSS THE BLUEGRASS.
THROUGH TUESDAY MOST LOCATIONS SHOULD BE SEEING BETWEEN 0.5 - 2
INCHES OF RAIN. SINCE IT IS CONVECTIVE IN NATURE...THE AMOUNTS CAN
BE QUITE VARIABLE. THE BLENDED MODEL TEMPERATURES LOOKED REALLY GOOD
AND ONLY HAD TO MAKE MINOR ADJUSTMENTS TO THE FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 225 PM EDT THU AUG 30 2012
EXPECT MAINLY VFR CONDITIONS TO CONTINUE THROUGH THE TAF PERIOD WITH
THE EXCEPTION OF SOME LOWER...MVFR...CLOUDS THIS AFTERNOON AND AGAIN
DURING THE DAY FRIDAY. THE INCREASE IN MOISTURE OVER THE SOUTHERN
PARTS OF THE FORECAST AREA SHOULD BE ENOUGH TO TRIGGER ISOLATED TO
SCATTERED CONVECTION BY LATE MORNING FRIDAY. TO ACCOUNT FOR THIS IN
THE TAFS HAVE ADDED A VCTS AND BKN040CB STARTING AT BETWEEN 12 AND
14Z. LIGHT AND VARIABLE WINDS THROUGH THE NIGHT WILL START TO PICK UP
FROM THE SOUTHWEST AT BETWEEN 5 AND 10 KTS DURING THE MORNING FRIDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...SHALLENBERGER
LONG TERM....JJ
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS GRAY ME
1152 AM EDT FRI AUG 31 2012
.SYNOPSIS...
A COLD FRONT WILL DROP SOUTH FROM CANADA TODAY AND WILL PUSH
OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE
NORTHWEST TONIGHT AND SATURDAY AND WILL SHIFT OFFSHORE ON SUNDAY.
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE COAST MONDAY. A COLD
FRONT WILL APPROACH FROM THE WEST MONDAY NIGHT AND WILL PUSH EAST
THROUGH NEW ENGLAND ON TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL
BUILD IN FROM THE WEST ON WEDNESDAY AND WILL HOLD OVER THE AREA ON
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
---1600Z UPDATE---
CLOUD COVER CONTINUES TO CAUSE ISSUES WITH FORECAST PACKAGE.
SHOWERS AND THUNDERSTORMS MOVING ACROSS NORTHERN VERMONT WILL
LIKELY HOLD TOGETHER LONG ENOUGH TO CROSS NEW HAMPSHIRE AND
SOUTHERN MAINE. WITH LITTLE IN THE WAY OF POSSIBLE SUNSHINE...WILL
CUT MAX TEMPERATURES SIGNIFICANTLY FOR TODAY. THIS IS ESPECIALLY
TRUE OVER THE NORTHERN HALF OF THE CWA WHERE TEMPERATURES HAVE YET
TO MAKE IT OUT OF THE 60S. WITH LACK OF SURFACE HEATING...WILL
ALSO REDUCE THE THREAT OF SEVERE THUNDERSTORMS OVER THE MOUNTAINS.
WILL TAKE OUT ENHANCED WORDING FOR THIS AFTERNOON.
---1400Z UPDATE---
SIGNIFICANT CLOUD COVER OVER THE COASTAL PLAIN THIS MORNING NOT
BEING CAPTURED WELL BY THE FORECAST. MODELS ALSO NOT DOING A VERY
GOOD JOB OF HANDLING THIS. THE RUC13 IS PROBABLY DOING THE BEST
JOB OF HANDLING THE CLOUD COVER. NOT SURE IT WILL HAVE MUCH IMPACT
ON HIGH TEMPERATURES FOR TODAY. UPDATED THE FORECAST TO ACCOUNT
FOR THE ADDITIONAL CLOUD COVER.
---1230Z UPDATE---
INTERESTING DAY SHAPING UP FOR NORTHERN NEW ENGLAND. MOST OF THE
MODELS ARE INDICATING A LATE AFTERNOON SEVERE WEATHER EVENT.
HOWEVER...THE LATEST RUN OF THE HRRR IS TRYING TO BRING SOME
CONVECTION INTO THE MOUNTAINS DURING THE LATE MORNING HOURS. WHEN
COMPARED WITH CURRENT RADAR TRENDS...THIS SCENARIO LOOKS PROBABLE.
THIS WILL THEN RAISE THE QUESTION ABOUT HOW WORKED OVER THE
AIRMASS WILL BE AS THE FRONTAL BOUNDARY APPROACHES LATER TODAY. AS
IT LOOKS NOW...WE MAY SEE SOME WEAK CONVECTION OVER THE MOUNTAINS
TODAY BUT THE CELLS WILL BE TOO FAR AWAY FROM THE UPPER LEVEL
SUPPORT TO REACH SEVERE LIMITS. HOWEVER...THERE SHOULD STILL BE
PLENTY OF TIME THIS AFTERNOON FOR THE AIRMASS TO RECOVER ITS
INSTABILITY AS TEMPERATURES RAPIDLY CLIMB. STILL LOOKS LIKE A
CHANCE FOR SOME ISOLATED SEVERE THUNDERSTORMS THIS
AFTERNOON...ESPECIALLY OVER THE MOUNTAINS. WILL UPDATE THE
FORECAST TO ADJUST POPS THIS MORNING AND TWEAK TEMPERATURES A BIT.
COLD FRONT DROPPING SOUTH FROM CANADA TODAY WILL BRING INCREASING
CLOUDS AND A CHANCE OF SHOWERS AND THUNDERSTORMS TO THE
REGION...MAINLY DURING THE AFTERNOON. FAIR AMOUNT OF SHEAR SETTING
UP ACROSS THE REGION EARLY THIS MORNING AND THIS WILL INCREASE
THROUGH EARLY AFTERNOON. ALTHOUGH CAPES WON`T BE TOO IMPRESSIVE
STRONG DYNAMICS MAY SUPPORT A FEW SUPER CELLS ACROSS NORTHERN
SECTIONS DURING THE MID TO LATE AFTERNOON. MAIN THREAT WITH THESE
STORMS WOULD BE DAMAGING WINDS AND LARGE HAIL. WILL INCLUDED
ENHANCED WORDING IN THE ZONES HIGHLIGHTING THESE CONCERNS.
FARTHER SOUTH WILL SEE INCREASING HIGH CLOUDS AND A CHANCE OF
AFTERNOON AND EVENING SHOWERS OR THUNDERSTORMS. TEMPERATURES
SHOULD TAKE A PRETTY GOOD JUMP THIS MORNING AS MIXING GETS GOING.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT ALREADY PUSHING TEMPS
INTO THE LOWER TO MID 70S IN MONTREAL AT 2 AM. 850 TEMPS GOOD
ENOUGH FOR LOWER 90S IN SOUTHERN NEW HAMPSHIRE INTO SOUTHWEST
MAINE.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
COLD FRONT WILL PUSH OFFSHORE BY LATE THIS EVENING AND EXPECT
CLEARING SKIES AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.
LOOKING FOR LOWS NEAR 50 IN THE NORTH AND MID 50S TO LOWER 60S IN
THE SOUTH.
BEAUTIFUL WEATHER FOR SATURDAY AS HIGH PRESSURE BUILDS IN FROM THE
WEST. LOOKING FOR ABUNDANT SUN AND SEASONABLE TEMPERATURES
THROUGHOUT THE FORECAST AREA.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
SFC HIGH PRES BUILDS IN SATURDAY NGT THEN MOVES E ON SUNDAY
PROVIDING FAIR WX...THOUGH THE MODELS DRIVE A SHORT WAVE TROF SE
THRU THE UPR LVL RIDGE OVER NEW ENGLAND ON SUNDAY. THIS WILL BRING
SOME CLOUDINESS AND MAYBE ISOLD SHRA THOUGH NOT MUCH MOISTURE OR
SFC SYSTEM TO SUPPORT MUCH, IF ANY, PRCP ON SUNDAY. THE UPR LVL
AND SFC RIDGE BECOME RE-ESTABLISHED OVER THE NE SUNDAY NGT AND
MONDAY WITH MORE FAIR WX. AN UPR LVL SHORT WAVE TROF MOVES E
MONDAY NGT AND TUESDAY AS MOISTURE INCREASES...GIVING US A CHC OF
PRCP. ANOTHER WEAK UPR LVL IMPULSE AND A SFC FNT CONT THE CHC OF
PRCP TUESDAY NGT INTO WEDNESDAY. HIGH PRES AND FAIR WX RETURNS
LATE WEDNESDAY INTO THURSDAY THOUGH ANOTHER UPR LVL TROF AND SFC
SYSTEM MOVING IN FROM THE W COULD PRODUCE A CHC OF PRCP LATE
THURSDAY.
GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SATURDAY
NGT AND SUNDAY. FOR REST OF THE LONG TERM FCST USED GMOS...EXCEPT
USED A BLEND OF GFS40, HPC GUIDANCE AND MEX MOS GUIDANCE FOR MAX AND
MIN TEMPS.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...VFR TODAY THROUGH SATURDAY. SOME ISOLATED MVFR/IFR
CEILINGS/VSBY THIS AFTERNOON IN SCATTERED THUNDERSTORMS.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...MOSTLY VFR WX THOUGH
SLGT CHC MVFR WITH -SHRA SUNDAY AND CHC OF MVFR WITH SHRA MONDAY
NGT AND TUESDAY.
&&
.MARINE...
SHORT TERM...INCREASING SOUTHWEST TO WEST FLOW WILL BRING GUSTS OF
25 TO 30 KT ON THE WATERS THIS MORNING THROUGH THIS EVENING WITH
SEAS BUILDING 4 TO 6 FT. HAVE ISSUED SCA FROM MID MORNING THROUGH
THIS EVENING.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...WEAK FLOW SATURDAY
NGT THRU SUNDAY NGT. SOUTHERLY ONSHORE FLOW INCREASE MONDAY AND
TUESDAY BUT LIKELY TO STAY BELOW SCA LEVELS. SEAS BELOW SCA LEVELS
SATURDAY NGT THRU SUNDAY NGT THEN THEY BUILD WITH THE INCREASING
ONSHORE FLOW MONDAY THRU TUESDAY...POSSIBLY REACHING SCA LEVELS ON
TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ150-152-
154.
&&
$$
POHL
AREA FORECAST DISCUSSION
NWS GRAY ME
1009 AM EDT FRI AUG 31 2012
.SYNOPSIS...
A COLD FRONT WILL DROP SOUTH FROM CANADA TODAY AND WILL PUSH
OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE
NORTHWEST TONIGHT AND SATURDAY AND WILL SHIFT OFFSHORE ON SUNDAY.
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE COAST MONDAY. A COLD
FRONT WILL APPROACH FROM THE WEST MONDAY NIGHT AND WILL PUSH EAST
THROUGH NEW ENGLAND ON TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL
BUILD IN FROM THE WEST ON WEDNESDAY AND WILL HOLD OVER THE AREA ON
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
---1400Z UPDATE---
SIGNIFICANT CLOUD COVER OVER THE COASTAL PLAIN THIS MORNING NOT
BEING CAPTURED WELL BY THE FORECAST. MODELS ALSO NOT DOING A VERY
GOOD JOB OF HANDLING THIS. THE RUC13 IS PROBABLY DOING THE BEST
JOB OF HANDLING THE CLOUD COVER. NOT SURE IT WILL HAVE MUCH IMPACT
ON HIGH TEMPERATURES FOR TODAY. UPDATED THE FORECAST TO ACCOUNT
FOR THE ADDITIONAL CLOUD COVER.
---1230Z UPDATE---
INTERESTING DAY SHAPING UP FOR NORTHERN NEW ENGLAND. MOST OF THE
MODELS ARE INDICATING A LATE AFTERNOON SEVERE WEATHER EVENT.
HOWEVER...THE LATEST RUN OF THE HRRR IS TRYING TO BRING SOME
CONVECTION INTO THE MOUNTAINS DURING THE LATE MORNING HOURS. WHEN
COMPARED WITH CURRENT RADAR TRENDS...THIS SCENARIO LOOKS PROBABLE.
THIS WILL THEN RAISE THE QUESTION ABOUT HOW WORKED OVER THE
AIRMASS WILL BE AS THE FRONTAL BOUNDARY APPROACHES LATER TODAY. AS
IT LOOKS NOW...WE MAY SEE SOME WEAK CONVECTION OVER THE MOUNTAINS
TODAY BUT THE CELLS WILL BE TOO FAR AWAY FROM THE UPPER LEVEL
SUPPORT TO REACH SEVERE LIMITS. HOWEVER...THERE SHOULD STILL BE
PLENTY OF TIME THIS AFTERNOON FOR THE AIRMASS TO RECOVER ITS
INSTABILITY AS TEMPERATURES RAPIDLY CLIMB. STILL LOOKS LIKE A
CHANCE FOR SOME ISOLATED SEVERE THUNDERSTORMS THIS
AFTERNOON...ESPECIALLY OVER THE MOUNTAINS. WILL UPDATE THE
FORECAST TO ADJUST POPS THIS MORNING AND TWEAK TEMPERATURES A BIT.
COLD FRONT DROPPING SOUTH FROM CANADA TODAY WILL BRING INCREASING
CLOUDS AND A CHANCE OF SHOWERS AND THUNDERSTORMS TO THE
REGION...MAINLY DURING THE AFTERNOON. FAIR AMOUNT OF SHEAR SETTING
UP ACROSS THE REGION EARLY THIS MORNING AND THIS WILL INCREASE
THROUGH EARLY AFTERNOON. ALTHOUGH CAPES WON`T BE TOO IMPRESSIVE
STRONG DYNAMICS MAY SUPPORT A FEW SUPER CELLS ACROSS NORTHERN
SECTIONS DURING THE MID TO LATE AFTERNOON. MAIN THREAT WITH THESE
STORMS WOULD BE DAMAGING WINDS AND LARGE HAIL. WILL INCLUDED
ENHANCED WORDING IN THE ZONES HIGHLIGHTING THESE CONCERNS.
FARTHER SOUTH WILL SEE INCREASING HIGH CLOUDS AND A CHANCE OF
AFTERNOON AND EVENING SHOWERS OR THUNDERSTORMS. TEMPERATURES
SHOULD TAKE A PRETTY GOOD JUMP THIS MORNING AS MIXING GETS GOING.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT ALREADY PUSHING TEMPS
INTO THE LOWER TO MID 70S IN MONTREAL AT 2 AM. 850 TEMPS GOOD
ENOUGH FOR LOWER 90S IN SOUTHERN NEW HAMPSHIRE INTO SOUTHWEST
MAINE.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
COLD FRONT WILL PUSH OFFSHORE BY LATE THIS EVENING AND EXPECT
CLEARING SKIES AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.
LOOKING FOR LOWS NEAR 50 IN THE NORTH AND MID 50S TO LOWER 60S IN
THE SOUTH.
BEAUTIFUL WEATHER FOR SATURDAY AS HIGH PRESSURE BUILDS IN FROM THE
WEST. LOOKING FOR ABUNDANT SUN AND SEASONABLE TEMPERATURES
THROUGHOUT THE FORECAST AREA.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
SFC HIGH PRES BUILDS IN SATURDAY NGT THEN MOVES E ON SUNDAY
PROVIDING FAIR WX...THOUGH THE MODELS DRIVE A SHORT WAVE TROF SE
THRU THE UPR LVL RIDGE OVER NEW ENGLAND ON SUNDAY. THIS WILL BRING
SOME CLOUDINESS AND MAYBE ISOLD SHRA THOUGH NOT MUCH MOISTURE OR
SFC SYSTEM TO SUPPORT MUCH, IF ANY, PRCP ON SUNDAY. THE UPR LVL
AND SFC RIDGE BECOME RE-ESTABLISHED OVER THE NE SUNDAY NGT AND
MONDAY WITH MORE FAIR WX. AN UPR LVL SHORT WAVE TROF MOVES E
MONDAY NGT AND TUESDAY AS MOISTURE INCREASES...GIVING US A CHC OF
PRCP. ANOTHER WEAK UPR LVL IMPULSE AND A SFC FNT CONT THE CHC OF
PRCP TUESDAY NGT INTO WEDNESDAY. HIGH PRES AND FAIR WX RETURNS
LATE WEDNESDAY INTO THURSDAY THOUGH ANOTHER UPR LVL TROF AND SFC
SYSTEM MOVING IN FROM THE W COULD PRODUCE A CHC OF PRCP LATE
THURSDAY.
GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SATURDAY
NGT AND SUNDAY. FOR REST OF THE LONG TERM FCST USED GMOS...EXCEPT
USED A BLEND OF GFS40, HPC GUIDANCE AND MEX MOS GUIDANCE FOR MAX AND
MIN TEMPS.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...VFR TODAY THROUGH SATURDAY. SOME ISOLATED MVFR/IFR
CEILINGS/VSBY THIS AFTERNOON IN SCATTERED THUNDERSTORMS.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...MOSTLY VFR WX THOUGH
SLGT CHC MVFR WITH -SHRA SUNDAY AND CHC OF MVFR WITH SHRA MONDAY
NGT AND TUESDAY.
&&
.MARINE...
SHORT TERM...INCREASING SOUTHWEST TO WEST FLOW WILL BRING GUSTS OF
25 TO 30 KT ON THE WATERS THIS MORNING THROUGH THIS EVENING WITH
SEAS BUILDING 4 TO 6 FT. HAVE ISSUED SCA FROM MID MORNING THROUGH
THIS EVENING.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...WEAK FLOW SATURDAY
NGT THRU SUNDAY NGT. SOUTHERLY ONSHORE FLOW INCREASE MONDAY AND
TUESDAY BUT LIKELY TO STAY BELOW SCA LEVELS. SEAS BELOW SCA LEVELS
SATURDAY NGT THRU SUNDAY NGT THEN THEY BUILD WITH THE INCREASING
ONSHORE FLOW MONDAY THRU TUESDAY...POSSIBLY REACHING SCA LEVELS ON
TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ150-152-
154.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
AREA FORECAST DISCUSSION
NWS GRAY ME
819 AM EDT FRI AUG 31 2012
.SYNOPSIS...
A COLD FRONT WILL DROP SOUTH FROM CANADA TODAY AND WILL PUSH
OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE
NORTHWEST TONIGHT AND SATURDAY AND WILL SHIFT OFFSHORE ON SUNDAY.
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE COAST MONDAY. A COLD
FRONT WILL APPROACH FROM THE WEST MONDAY NIGHT AND WILL PUSH EAST
THROUGH NEW ENGLAND ON TUESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL
BUILD IN FROM THE WEST ON WEDNESDAY AND WILL HOLD OVER THE AREA ON
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
---1230Z UPDATE---
INTERESTING DAY SHAPING UP FOR NORTHERN NEW ENGLAND. MOST OF THE
MODELS ARE INDICATING A LATE AFTERNOON SEVERE WEATHER EVENT.
HOWEVER...THE LATEST RUN OF THE HRRR IS TRYING TO BRING SOME
CONVECTION INTO THE MOUNTAINS DURING THE LATE MORNING HOURS. WHEN
COMPARED WITH CURRENT RADAR TRENDS...THIS SCENARIO LOOKS PROBABLE.
THIS WILL THEN RAISE THE QUESTION ABOUT HOW WORKED OVER THE
AIRMASS WILL BE AS THE FRONTAL BOUNDARY APPROACHES LATER TODAY. AS
IT LOOKS NOW...WE MAY SEE SOME WEAK CONVECTION OVER THE MOUNTAINS
TODAY BUT THE CELLS WILL BE TOO FAR AWAY FROM THE UPPER LEVEL
SUPPORT TO REACH SEVERE LIMITS. HOWEVER...THERE SHOULD STILL BE
PLENTY OF TIME THIS AFTERNOON FOR THE AIRMASS TO RECOVER ITS
INSTABILITY AS TEMPERATURES RAPIDLY CLIMB. STILL LOOKS LIKE A
CHANCE FOR SOME ISOLATED SEVERE THUNDERSTORMS THIS
AFTERNOON...ESPECIALLY OVER THE MOUNTAINS. WILL UPDATE THE
FORECAST TO ADJUST POPS THIS MORNING AND TWEAK TEMPERATURES A BIT.
COLD FRONT DROPPING SOUTH FROM CANADA TODAY WILL BRING INCREASING
CLOUDS AND A CHANCE OF SHOWERS AND THUNDERSTORMS TO THE
REGION...MAINLY DURING THE AFTERNOON. FAIR AMOUNT OF SHEAR SETTING
UP ACROSS THE REGION EARLY THIS MORNING AND THIS WILL INCREASE
THROUGH EARLY AFTERNOON. ALTHOUGH CAPES WON`T BE TOO IMPRESSIVE
STRONG DYNAMICS MAY SUPPORT A FEW SUPER CELLS ACROSS NORTHERN
SECTIONS DURING THE MID TO LATE AFTERNOON. MAIN THREAT WITH THESE
STORMS WOULD BE DAMAGING WINDS AND LARGE HAIL. WILL INCLUDED
ENHANCED WORDING IN THE ZONES HIGHLIGHTING THESE CONCERNS.
FARTHER SOUTH WILL SEE INCREASING HIGH CLOUDS AND A CHANCE OF
AFTERNOON AND EVENING SHOWERS OR THUNDERSTORMS. TEMPERATURES
SHOULD TAKE A PRETTY GOOD JUMP THIS MORNING AS MIXING GETS GOING.
STRONG SOUTHWEST FLOW AHEAD OF THE FRONT ALREADY PUSHING TEMPS
INTO THE LOWER TO MID 70S IN MONTREAL AT 2 AM. 850 TEMPS GOOD
ENOUGH FOR LOWER 90S IN SOUTHERN NEW HAMPSHIRE INTO SOUTHWEST
MAINE.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
COLD FRONT WILL PUSH OFFSHORE BY LATE THIS EVENING AND EXPECT
CLEARING SKIES AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.
LOOKING FOR LOWS NEAR 50 IN THE NORTH AND MID 50S TO LOWER 60S IN
THE SOUTH.
BEAUTIFUL WEATHER FOR SATURDAY AS HIGH PRESSURE BUILDS IN FROM THE
WEST. LOOKING FOR ABUNDANT SUN AND SEASONABLE TEMPERATURES
THROUGHOUT THE FORECAST AREA.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
SFC HIGH PRES BUILDS IN SATURDAY NGT THEN MOVES E ON SUNDAY
PROVIDING FAIR WX...THOUGH THE MODELS DRIVE A SHORT WAVE TROF SE
THRU THE UPR LVL RIDGE OVER NEW ENGLAND ON SUNDAY. THIS WILL BRING
SOME CLOUDINESS AND MAYBE ISOLD SHRA THOUGH NOT MUCH MOISTURE OR
SFC SYSTEM TO SUPPORT MUCH, IF ANY, PRCP ON SUNDAY. THE UPR LVL
AND SFC RIDGE BECOME RE-ESTABLISHED OVER THE NE SUNDAY NGT AND
MONDAY WITH MORE FAIR WX. AN UPR LVL SHORT WAVE TROF MOVES E
MONDAY NGT AND TUESDAY AS MOISTURE INCREASES...GIVING US A CHC OF
PRCP. ANOTHER WEAK UPR LVL IMPULSE AND A SFC FNT CONT THE CHC OF
PRCP TUESDAY NGT INTO WEDNESDAY. HIGH PRES AND FAIR WX RETURNS
LATE WEDNESDAY INTO THURSDAY THOUGH ANOTHER UPR LVL TROF AND SFC
SYSTEM MOVING IN FROM THE W COULD PRODUCE A CHC OF PRCP LATE
THURSDAY.
GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SATURDAY
NGT AND SUNDAY. FOR REST OF THE LONG TERM FCST USED GMOS...EXCEPT
USED A BLEND OF GFS40, HPC GUIDANCE AND MEX MOS GUIDANCE FOR MAX AND
MIN TEMPS.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...VFR TODAY THROUGH SATURDAY. SOME ISOLATED MVFR/IFR
CEILINGS/VSBY THIS AFTERNOON IN SCATTERED THUNDERSTORMS.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...MOSTLY VFR WX THOUGH
SLGT CHC MVFR WITH -SHRA SUNDAY AND CHC OF MVFR WITH SHRA MONDAY
NGT AND TUESDAY.
&&
.MARINE...
SHORT TERM...INCREASING SOUTHWEST TO WEST FLOW WILL BRING GUSTS OF
25 TO 30 KT ON THE WATERS THIS MORNING THROUGH THIS EVENING WITH
SEAS BUILDING 4 TO 6 FT. HAVE ISSUED SCA FROM MID MORNING THROUGH
THIS EVENING.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...WEAK FLOW SATURDAY
NGT THRU SUNDAY NGT. SOUTHERLY ONSHORE FLOW INCREASE MONDAY AND
TUESDAY BUT LIKELY TO STAY BELOW SCA LEVELS. SEAS BELOW SCA LEVELS
SATURDAY NGT THRU SUNDAY NGT THEN THEY BUILD WITH THE INCREASING
ONSHORE FLOW MONDAY THRU TUESDAY...POSSIBLY REACHING SCA LEVELS ON
TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ150-152-
154.
&&
$$
POHL
AREA FORECAST DISCUSSION
NWS CARIBOU ME
101 AM EDT FRI AUG 31 2012
.SYNOPSIS...
LOW PRESSURE WILL TRACK NORTH OF MAINE OVERNIGHT THROUGH
FRIDAY...DRAWING A COLD FRONT ACROSS THE REGION FRIDAY. HIGH
PRESSURE WILL BUILD ACROSS THE REGION THROUGH THE WEEKEND.&&
.NEAR TERM /THROUGH TODAY/...
1230 AM UPDATE: UPDATED POPS AND WX GRIDS TO MENTION SCT SHWRS
ACROSS ALL OF NRN AROOSTOOK COUNTY (ZONES 1 AND 2) FOR THE
REMAINDER OF THE NGT. ALTHOUGH HRRR RAPID UPDATE MODEL DATA
DOES NOT INDICATE TSTMS CURRENTLY IN THE ST LAWRENCE VLY AREA
OF QB NEAR ALMA AND BAGOTTSVILLE MAKING IT INTO OUR FA BEFORE
DISSIPATING...WE DO MENTION ISOLD TSTMS CAPABLE OF PRODUCING
GUSTY WINDS TIL ABOUT DAYBREAK. MOST OF THIS ACTIVITY SHOULD
MOVE OUT OF NRN AREAS BY 12Z.
WE ALSO WENT AHEAD AND DERIVED THE POP DISTRIBUTION FOR SHWRS/TSTMS
FOR FRI DAY AND EVE...INCLUDING ENHANCED WORDING FOR HAIL AND
CNVCTV WINDS AND QPF WITH TSTMS FRI AFTN INTO ERLY EVE ASSOCIATED
WITH AN ADVANCING COLD FRONT...BUT MORE DETAILS ON THIS WITH THE
NEXT FCST UPDATE.
PREV UPDATE: LOW PRESSURE WILL BEGIN TO TRACK NORTH OF MAINE
OVERNIGHT...WITH HIGH PRESSURE TO THE SOUTH. THE LOW WILL DRAW A
COLD FRONT TOWARD THE REGION LATE TONIGHT. PARTLY/MOSTLY CLOUDY
SKIES WILL EXIST ACROSS NORTHERN AREAS OVERNIGHT ALONG WITH A
CHANCE OF SHOWERS. MOSTLY CLEAR SKIES ARE EXPECTED DOWNEAST
OVERNIGHT. OVERNIGHT LOW TEMPERATURES WILL GENERALLY RANGE FROM
THE UPPER 50S TO THE LOWER 60S ACROSS THE FORECAST AREA. HAVE
UPDATED THE FORECAST TO ADJUST FOR CURRENT CONDITIONS ALONG WITH
EXPECTED OVERNIGHT CLOUD COVER/SHOWER CHANCES/TEMPERATURES. HAVE
SLIGHTLY INCREASED SHOWER CHANCES ACROSS NORTHERN AREAS OVERNIGHT.
ORGNL DISC: THE LOW MOVING NORTH OF MAINE FRIDAY WILL PULL A COLD FRONT
ACROSS THE AREA. FORECAST CAPES AHEAD OF THE FRONT RANGE FROM
AROUND 1500 J/KG ON THE NAM TO 500 J/KG ON THE GFS. THE SHEARING
ENVIRONMENT IS VERY STRONG WITH WINDS INCREASING FROM AROUND 15KT
ON THE SURFACE TO ALMOST 40 KT AT 5000 FT. THE SHEAR COULD MAKE IT
DIFFICULT FOR CONVECTION TO DEVELOP. HOWEVER...CONVECTION THAT
DOES DEVELOP COULD RESULT IN STRONG GUSTY AND POSSIBLY DAMAGING
WINDS DUE TO THE STRONG WINDS ALOFT THAT COULD CARRY MOMENTUM TO
THE SURFACE IN ANY DOWNDRAFTS. THE FRONT WILL REACH THE DOWNEAST
REGION LATE FRIDAY AS COOLER AIR BEGINS TO FILTER INTO THE NORTH.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
COOLER, DRIER AIR TO MOVE IN FRIDAY NIGHT AS A COLD FRONT PASSES
THROUGH THE AREA FROM NORTHWEST TO SOUTHEAST. WEAK UPPER LEVEL
RIDGE AND A SURFACE HIGH PRESSURE OVERHEAD ON SATURDAY WILL LEAD
TO A VERY PLEASANT DAY. HIGH PRESSURE OVERHEAD SATURDAY NIGHT WILL
ALLOW FOR TEMPERATURES TO DROP EASILY INTO THE 40S FOR MOST AREAS,
WITH SOME 30S IN PROTECTED VALLEYS OF NORTHERN MAINE. A WEAK UPPER
LEVEL TROUGH WILL PASS THROUGH DURING THE DAY SUNDAY, IGNITING
ISOLATED TO SCATTERED SHOWERS MAINLY DURING THE AFTERNOON.
MODELS ARE IN GOOD AGREEMENT FRIDAY NIGHT THROUGH SUNDAY. PRIMARY
CHANGE TO PREVIOUS FORECAST WAS TO INTRODUCE 20 TO 40 PERCENT POPS
FOR SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE BUILDS IN FOR MONDAY BUT IS QUICKLY REPLACED BY
UPPER LEVEL SOUTHWEST FLOW AND MOIST LOW LEVEL SOUTHERLY FLOW
TUESDAY AND WEDNESDAY. SOME OF THE MOISTURE MOVING INTO THE AREA
WILL BE FROM THE REMNANTS OF ISAAC. A GOOD CHANCE OF SOME RAIN
DURING THIS PERIOD. MODEL AGREEMENT FALLS APART FROM LATE
WEDNESDAY ONWARD ON WHETHER WE DRY OUT OR REMAIN WET. WENT WITH A
MIDDLE OF THE ROAD APPROACH FOR NOW.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: GENERALLY VFR CONDITIONS ARE EXPECTED ACROSS THE REGION
OVERNIGHT...THOUGH OCCASIONAL MVFR CONDITIONS COULD OCCUR ACROSS
NORTHERN AREAS LATE. OCCASIONAL MVFR/IFR CONDITIONS COULD OCCUR
WITH ANY SHOWERS AND THUNDERSTORMS FRIDAY. GUSTY WINDS WILL ALSO
OCCUR ACROSS THE REGION FRIDAY...WITH STRONGER WINDS POSSIBLE WITH
ANY THUNDERSTORMS.
SHORT TERM: GENERALLY VFR CONDITIONS EXPECTED FRIDAY NIGHT
THROUGH MONDAY. MVFR CONDITIONS ARE POSSIBLE TUESDAY.
&&
.MARINE...
NEAR TERM: WINDS/SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT
ADVISORY LEVELS OVERNIGHT. SMALL CRAFT ADVISORY LEVEL WINDS/SEAS
ARE THEN POSSIBLE FRIDAY.
SHORT TERM: WINDS WILL SHIFT FROM SOUTHWEST TO NORTH FRIDAY NIGHT
AS A COLD FRONT PASSES THROUGH. WINDS AND SEAS WILL BE AT OR JUST
BELOW SMALL CRAFT LEVELS FRIDAY NIGHT, BUT CONDITIONS CALM DOWN
FOR SATURDAY AND SUNDAY WITH HIGH PRESSURE OVERHEAD.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...VJN
SHORT TERM...FOISY
LONG TERM...FOISY
AVIATION...VJN
MARINE...VJN/FOISY
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
406 PM EDT FRI AUG 31 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 401 PM EDT FRI AUG 31 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE PACIFIC
NW...RIDGING DOWNSTREAM OVER THE NRN PLAINS/SCNTRL CANADA AND A TROF
OVER SE CANADA/NEW ENGLAND. THE UPSTREAM RIDGE IS CURRENTLY GAINING
AMPLITUDE. WITH THE RIDGE CONTINUING TO BUILD THRU SAT AS IT SHIFTS
E TOWARD THE UPPER LAKES...THE SHORT TERM PORTION OF THE FCST WILL
BE TRANQUIL. THERE IS AN AREA OF MID/HIGH CLOUDS OVER THE DAKOTAS...
AND THE CLOUDS HAVE SOME SUPPORT FROM THE RIGHT ENTRANCE OF UPPER
JET ALONG THE U.S./CANADA BORDER THRU THE UPPER LAKES. SINCE THE
UPPER JET SUPPORT BREAKS DOWN TONIGHT...CLOUDS SHOULD TEND TO
DISSIPATE AND PROBABLY WON`T BE MUCH OF A FACTOR HERE. UNDER MAINLY
CLR SKIES...WINDS WILL DROP OFF TO CALM/NEAR CALM AS SFC HIGH PRES
OVER NW MN SETTLES OVER THE UPPER GREAT LAKES TONIGHT. COMBINED
WITH A DRY COLUMN (PRECIPITABLE WATER 50-60PCT OF NORMAL)...TONIGHT
WILL BE A STRONG RADIATIONAL COOLING NIGHT. OPTED TO GO AT OR BLO
THE LOWEST GUIDANCE OVER THE INTERIOR...ESPECIALLY THE W SINCE
WINDS THERE WILL FALL TO CALM AROUND SUNSET. EXPECT MINS AS LOW AS
THE UPPER 30S IN THE TRADITIONAL COLD SPOTS. DIMINISHING SOIL
MOISTURE DUE TO RECENT DRY SPELL WILL ALSO AID COOLING POTENTIAL
TONIGHT. TYPICAL FOR THIS TIME OF YEAR...LENGTHENING NIGHTS AND WARM
WATER IN SWAMPS/STREAMS/RIVERS/LAKES MAY LEAD TO SOME GROUND FOG.
UNDER MOSTLY SUNNY SKIES...THE FIRST DAY OF METEOROLOGICAL AUTUMN
WILL BE A NICE ONE. ALTHOUGH TEMPS WILL BE ABOVE NORMAL...LOW DWPTS
WILL MAKE FOR A COMFORTABLE DAY. MIXING TOWARD 800MB ON FCST
SOUNDINGS YIELDS MAX TEMPS AROUND 80F INTO THE LWR 80S IN THE
INTERIOR. WITH SFC HIGH SETTING UP OVER LAKE SUPERIOR...LAKESIDE
LOCATIONS WILL HOLD TO THE LOW/MID 70S. WEAKER LAKE BREEZE OFF LAKE
MI WILL PROVIDE LIMITED COOLING. AFTN DWPTS WILL LIKELY FALL TOWARD
THE LWR 40S IN THE INTERIOR BASED ON MIXING DEPTH. ALTHOUGH RH WILL
BOTTOM OUT AS LOW AS THE 25-30PCT RANGE...LIGHT WINDS WILL HELP TO
EASE FIRE WX CONCERNS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 401 PM EDT FRI AUG 31 2012
SATURDAY NIGHT...
THE APEX OF THE SFC TO 500MB RIDGE WILL BE NEAR THE CWA AT 00Z
SUNDAY...WITH THE REMNANTS OF ISAAC ACROSS MO. LOOK FOR THE SFC HIGH
TO SHIFT E TO THE ONTARIO/QUEBEC BORDER AND LOWER GREAT LAKES
OVERNIGHT...WITH A WEAK RETURN OF SSE FLOW WITH SOME MOISTENING OF
THE ATMOSPHERE THANKS TO WINDS PUSHING N AROUND WHAT IS LEFT OF
ISAAC. PW VALUES STARTING OFF AROUND 0.5IN EAST /55 PERCENT OF
NORMAL/ JUMPING TO VALUES RIGHT AROUND NORMAL FOR THIS TIME OF YEAR
BY 12Z SUNDAY...OR 0.75 TO 1IN.
SUNDAY THROUGH SUNDAY NIGHT...
SLIGHT SW FLOW BEGINS ALOFT BEGINS SUNDAY...AND BECOMES MORE ZONAL
MONDAY AS THE 500MB LOW TRANSITIONING ACROSS CENTRAL/S CANADA PUSHES
ACROSS SASKATCHEWAN AND MANITOBA. THERE ARE SIGNIFICANT
DISCREPANCIES WRT THE 31/06Z GFS AND 31/00Z ECMWF...WITH THE 31/00Z
CANADIAN LOOKING TO BE A CLOSE BLEND OF THE 2. THE 12Z RUNS OF THE
GFS AND ECMWF ARE MOVING CLOSER TO A SIMILAR SOLUTION WITH THE
CANADIAN TRACKING LOW. THE RESULT WILL BE AN INCREASE IN
MOISTURE...WITH THE SFC LOW OVER N SASKATCHEWAN AT 18Z SUNDAY...AND
THE COLD FRONT EXTENDING THROUGH THE DAKOTAS AND CENTRAL PLAINS.
EXPECT INCREASED S WINDS SUNDAY NIGHT IN ADVANCE OF THE COLD
FRONT...WITH A CHANCE OF TSRA WEST BY DAYBREAK MONDAY.
MONDAY THROUGH TUESDAY...
THE SFC COLD FRONT SET UP OVER FAR W LAKE SUPERIOR AT 12Z MONDAY /OR
EVEN ACROSS THE KEWEENAW PENINUSLA ACCORDING TO THE 31/00Z
ECMWF/...WILL PUSH JUST E OR RIGHT ACROSS THE FAR E END OF THE CWA
BY 00Z TUESDAY. SO FOR MEMORIAL DAY...A CHANCE OF TSRA WILL CONTINUE
TO TRACK E...WITH IMPROVING CONDITIONS W BY EARLY AFTERNOON. I
ATTEMPTED TO KEEP THE BEST CHANCE OF THUNDER RIGHT ALONG AND JUST
AHEAD OF THE FRONT. MONDAY NIGHT STILL LOOKS TO BE MAINLY DRY AS
HIGH PRESSURE PUSHES IN FROM THE SSW...AS TEMPS FALL INTO THE MID
50S INTERIOR W.
TUESDAY NIGHT THROUGH FRIDAY...
UNSETTLED WEATHER AND A RETURN TO NEAR NORMAL TEMPS WILL LIKELY BE
THE NORM FROM TUESDAY NIGHT THROUGH FRIDAY AS A SERIES OF
DISTURBANCES PUSH OVER OR JUST NORTH OF THE CWA. GIVEN THE FCST
DISCREPANCIES FROM THE VARIOUS MODELS...WILL NOT BE TERRIBLY
SPECIFIC WITH TIMING AS LOW PRESSURE SYSTEMS PUSH NEAR OR JUST N OF
LAKE SUPERIOR.
WINDS WEDNESDAY WILL LIKELY BE HIGHER THAN FORECAST. THE MAIN
DILEMMA HERE STEMS FROM AN AVERAGING OF MODEL GUIDANCE
DIRECTIONS...NW OFF THE GFS AND S OFF THE ECMWF. THE 12Z RUNS GIVE
GETTER CONFIDENCE IN A MORE NW FLOW SOLUTION...SIMILAR TO THE 06Z
RUN OF THE GFS. THIS WILL NEED TO BE LOOKED AT A BIT CLOSER OVER THE
NEXT COUPLE OF RUNS...TO MAKE SURE THIS TREND CONTINUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 125 PM EDT FRI AUG 31 2012
VFR CONDITIONS WILL BE THE RULE AT KIWD/KCMX/KSAW AS DRY HIGH
PRESSURE BUILDS OVER THE REGION THRU SAT.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 401 PM EDT FRI AUG 31 2012
AS SFC HIGH PRES SETTLES OVER LAKE SUPERIOR TONIGHT AND SAT...WINDS
WILL MOSTLY BE UNDER 15KT. AS THE HIGH SHIFTS TO THE E SAT NIGHT/SUN
AND A COLD FRONT APPROACHES FROM THE W...SOUTHEASTERLY WINDS WILL
GRADUALLY INCREASE...REACHING 10-20KT. SOUTHERLY WINDS MAY GUST UP
TO AROUND 25KT SUN NIGHT/EARLY MON JUST AHEAD OF THE FRONT. THE
STRONGER WINDS WILL BE OBSERVED ON THE HIGHER OBS PLATFORMS. PRES
GRADIENT THEN SLACKENS WITH PASSING COLD FRONT MON...RESULTING IN
WINDS DIMINISHING BACK TO UNDER 15KT MON INTO TUE. THE LIGHTER WINDS
WILL THEN PERSIST INTO WED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
717 AM EDT FRI AUG 31 2012
.SYNOPSIS...
ISSUED AT 352 AM EDT FRI AUG 31 2012
A WEAK COLD FRONT WILL DROP SOUTH THROUGH THE AREA TODAY.
TEMPERATURES AHEAD OF THE FRONT WILL CLIMB WELL INTO THE 80S AND
APPROACH 90 IN SOME LOCATIONS. TEMPERATURES FOR THE WEEKEND INTO
NEXT WEEK WILL REMAIN ABOVE NORMAL. CHANCES FOR RAIN WILL
GENERALLY BE LIMITED TO THE SOUTHERN PORTION OF THE STATE AS THE
TROPICAL SYSTEM MOVES TO THE OHIO VALLEY.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 352 AM EDT FRI AUG 31 2012
FORECAST CONCERNS ARE SOMEWHAT LIMITED THIS MORNING AND MAINLY
DEAL WITH THE COLD FRONT PASSING THROUGH TODAY AND CHANCES FOR
RAIN AS THE TROPICAL LOW MOVES NORTH.
THE FORECAST HASN/T CHANGED MUCH AND CONFIDENCE IS REASONABLY HIGH
THAT WE/RE NOT GOING TO SEE MUCH PCPN FOR THE NEXT FEW DAYS.
LATEST IR LOOP SHOWS A BAND OF CLOUDS FROM SOUTH DAKOTA NEWD INTO
SRN ONTARIO. THIS MARKS THE WEAK COLD FRONT THAT WILL MOVE SOUTH
TODAY. TEMPS AHEAD OF THE FRONT WILL CLIMB TO NEAR 90 DEGREES
SOUTH OF I-94 THIS AFTERNOON. MODERATE INSTABILITY WILL BE PRESENT
TOO. HOWEVER...DUE TO THE LACK OF APPRECIABLE MOISTURE CONFIDENCE
IS LOW THAT WE/LL SEE ANY RAIN ALONG THE FRONT. CAN/T RULE IT OUT
COMPLETELY BUT CHANCES ARE LOW ENOUGH THAT WE HAVE DRY GRIDS
TODAY...WHICH IS A CONTINUATION OF THE CURRENT FORECAST. HIGH
PRESSURE WILL BUILD INTO THE REGION AND FUNNEL DRY AIR INTO THE
REGION. THIS HIGH WILL KEEP THE TROPICAL SYSTEM FROM MOVING NORTH
INTO THE GREAT LAKES. AS IT FUNNELS DRY AIR SWWD FROM
ONTARIO...WE/LL LIKELY SEE A SHARP PCPN GRADIENT FROM SRN LWR MI
INTO NRN INDIANA. WE/RE NOT GOING TO SEE MUCH IF ANY RAIN FROM
THIS SYSTEM. WE RAIN FALLS IN THE CWA WILL LIKELY BE SOUTH OF I-94
SATURDAY NIGHT INTO SUNDAY.
.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 352 AM EDT FRI AUG 31 2012
THE PRIMARY WEATHER ISSUES FOR THIS COMING WEEK ARE RELATED TO THE
POTENTIAL FOR CONVECTION WITH THE COLD FRONT MONDAY AND THEN AGAIN
THURSDAY.
IT WOULD NOW SEEMS A STRONG STORM COMING OFF THE KAMCHATKA PENINSULA
MONDAY BECOMES THE DOMINATE UPPER LEVEL WAVE FEATURE IN THE NORTHERN
HEMISPHERE. IT DEVELOPS A DEEP BUT NONE THE LESS PROGRESSIVE UPPER
TROUGH WITH A 160 KNOT JET CORE WHICH IS STILL DIGGING INTO THE WEST
SIDE OF THAT TROUGH TUESDAY MORNING. THAT SYSTEM PICKS UP REMNANT
LOW FROM A FORMER WEST PACIFIC TYPHOON. THIS COMBINED SYSTEM REACHES
THE DATELINE BY WEDNESDAY. THIS OF COURSE BUILDS A LARGE UPPER RIDGE
IN FRONT OF IT. THAT IS OVER THE WEST COAST OF NORTH AMERICA FROM
CALIFORNIA TO CENTRAL ALASKA IN THE WEDNESDAY TIME FRAME. THIS THEN
SETS THE STAGE FOR SOME SIGNIFICANT DOWN STREAM WEATHER CHANGES THAT
IMPACT SOUTHWEST MICHIGAN (THINK FALL LIKE WEATHER). THIS ACTUALLY
HAS BEEN A RATHER STABLE FEATURE OF THE MODELS OVER THE PAST FEW
DAYS. BY THE WAY THIS ALSO GOES ALONG WITH THE MJO PHASE PROGRESSION
(WHICH SUGGESTS WARM INTO MID WEEK HERE THEN COOLER).
MY DISCUSSION FROM YESTERDAY TALKED ABOUT A SYSTEM OFF BRITISH
COLUMBIA COAST POSSIBLY PHASING WITH A SYSTEM NOW OVER WESTERN
ALASKA. ALL OF THAT IS FORCED BY THE SYSTEM FROM NORTHERN RUSSIA
DIGGING THE DEEP TROUGH WEST OF THE DATELINE.
SO WHAT DOES THIS MEAN FOR SOUTHWEST MICHIGAN WEATHER? IT MEANS WE
GET TWO COLD FRONTS THIS WEEK. BOTH OF WHICH MAY HAVE CONVECTION
WITH THEM. THE LEAD SYSTEM TRIES TO COME THROUGH MONDAY BUT THE
TRAILING SYSTEM IS STRONGER AND DEEPER SO IT BOOTS THE LEAD SYSTEM
OUT OF THE WAY. THAT MEANS THE COLD FRONT WILL WEAKEN AS IT COMES
THROUGH AND IN SO DOING WILL NOT BE PULLING DOWN MUCH COOL AIR
BEHIND IT FOR TUESDAY AND WEDNESDAY. EVEN SO WE COULD GET INTO THE
JET ENTRANCE REGION LIFT AREA MONDAY AFTERNOON OR EVENING. THAT
WOULD HELP THE CAUSE FOR A FEW THUNDERSTORMS BUT MOISTURE IS LIMITED
SO I KEPT THE POP LOW FOR THIS EVENT.
THE BETTER EVENT WILL BE LATER IN THE WEEK AS THE SYSTEM FROM
WESTERN ALASKA COMES INTO THE PICTURE. BY THEN THE WESTERN RIDGE
WILL HAVE HAD A CHANCE TO REALLY BUILD WHICH IN TURN DEEPS THE DOWN
STREAM TROUGH OVER THE GREAT LAKES. IT IS AT THIS TIME OUR CHANCE OF
A SIGNIFICANT CONVECTIVE EVENT WOULD BE. GIVEN THE STRENGTH OF THE
UP STREAM SYSTEM DRIVING THIS... I COULD SEE THIS SLOWING DOWN BY 12
TO 24 HOURS THROUGH. SO I HAVE LOW POPS FOR THURSDAY YET BUT I FEEL
STRONGLY THIS SYSTEM LATE IN THE WEEK OVERALL WILL GIVE SOUTHWEST
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 718 AM EDT FRI AUG 31 2012
BREEZY WITH VFR CONDITIONS INTO THIS AFTERNOON. VFR CONDITIONS
EXPECTED TONIGHT.
THE STRONG WINDS... WEST 40 KNOTS ARE SHOWING UP ON OUR VAD WIND
PROFILE THIS MORNING BETWEEN 2000 AND 3000 FT AGL. WINDS ARE
SOUTHWEST 5 TO 15 KNOTS BELOW 10000 FT AGL. SO THE LOW LEVEL WIND
SHEAR WILL CONTINUE UNTIL THE BOUNDARY LAYER MIXES OUT BETWEEN 13Z
AND 15Z. ONCE IT DOES THROUGH SURFACE WINDS WILL BE GUSTY FROM THE
WEST... LIKE 15 KNOTS GUSTING TO 25 KNOTS. WINDS WILL BE STRONGER
OVER FOR THE MORE EASTERN TAF SITES LIKE LANSING.
SKIES SHOULD BE NEARLY CLEAR THROUGH EARLY AFTERNOON EVEN WITH
THE FRONT DROPPING SOUTH INTO THE AREA BY MID AFTERNOON. THE AIR IS
SO DRY ON THE RAP SOUNDINGS THAT THE LCL IS NEAR 12000 FT INTO
LATE MORNING. I WOULD EXPECT SOME HIGH BASED MID CLOUDS BEHIND THE
FRONT TONIGHT SO I BROUGHT IN A MID CLOUD DECK FOR THAT. WINDS
WILL BECOME LIGHT FROM THE NORTH NORTHEAST AT THE SURFACE BEHIND
THE COLD FRONT.
&&
.MARINE...
ISSUED AT 352 AM EDT FRI AUG 31 2012
SCA CONTINUES INTO THE AFTERNOON. WINDS WILL SLOWLY DIMINISH AND
SCA CONDITIONS WILL SUBSIDE LATE IN THE DAY.
&&
.HYDROLOGY...
ISSUED AT 352AM EDT FRI AUG 31 2012
VERY LITTLE RAINFALL EXPECTED OVER THE WEEKEND. A QUARTER INCH OR
LESS POSSIBLE SOUTH OF I-94 THROUGH SUNDAY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 3 PM EDT THIS AFTERNOON FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR
LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1208 AM CDT FRI AUG 31 2012
.AVIATION...
VFR IS EXPECTED ALL AREAS OVERNIGHT THROUGH FRIDAY EVENING.
NO TSTMS ARE FORECAST. SOUTH WINDS DEVELOP FRIDAY IN RESPONSE TO LOW
PRESSURE DEVELOPING ACROSS THE NRN HIGH PLAINS.
&&
.PREV DISCUSSION... /ISSUED 908 PM CDT THU AUG 30 2012/
UPDATE...
DISCUSSION...
WINDS HAVE DECREASED WELL BELOW 25 MPH AND RELATIVE HUMIDITY HAS
RECOVERED TO OVER 20 PERCENT IN MOST AREAS. THE RED FLAG WARNING
HAS BEEN CANCELLED. A FIRE WEATHER WATCH CONTINUES FOR FRIDAY.
PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 30 2012/
SYNOPSIS...
SURFACE ANALYSIS THIS AFTERNOON...AS A COLD FRONT EXTENDING FROM
AROUND LEWELLEN...TO ARTHUR...TO DUNNING...TO EWING. NORTH OF THIS
FEATURE...TEMPS RANGE FROM 80 AT VALENTINE...TO 94 AT O`NEILL. SOUTH
OF THE FRONT...TEMPS WERE AROUND 100 DEGREES WITH RELATIVE
HUMIDITIES RANGING FROM 5 TO 15 PERCENT. A MAJOR FIRE WAS BURNING
ACROSS NORTHWESTERN SHERIDAN COUNTY THIS AFTERNOON AT THE METCALF
STATE WILDLIFE MANAGEMENT AREA. EVACUATION ORDERS HAVE BEEN GIVEN
FOR THIS AREA OF SHERIDAN COUNTY. ADDITIONAL DETAILS ARE IN
OMAEVILBF.
ALOFT AT H5...RIDGING HAS BEGUN TO TRANSITION EAST THIS MORNING...AS
A TROUGH OF LOW PRESSURE BUILDS ALONG THE PACIFIC NW COAST. AT 12Z
THIS MORNING...ISSAC WAS LOCATED NORTHWEST OF BATON ROUGE LA.
DISCUSSION...
SHORT RANGE...TONIGHT THROUGH SUNDAY...MAIN FORECAST CHALLENGE IS
TEMPERATURES AND FIRE WEATHER CONCERNS OVER THE NEXT 24 TO 36 HRS.
FOR TONIGHT...THE LATEST NAM SOLN STALLS THE COLD FRONT ALONG
HIGHWAYS 92 AND 91 THIS EVENING...WHILE THE HIGH RES RUC PUSHES THIS
FEATURE THROUGH NORTH PLATTE TO JUST SOUTH OF INTERSTATE 80. EVEN
WITH A MORE AGGRESSIVE FRONTAL PUSH DEPICTED BY THE HI RES
RUC...LOCATIONS AHEAD OF THE FRONT HAVE ALREADY TORCHED OUT THIS
AFTERNOON WITH WIDESPREAD HIGHS WELL ABOVE THE CENTURY MARK AND
RELATIVE HUMIDITIES AS LOW AS 5 PERCENT. AS SURFACE HIGH PRESSURE
BUILDS EAST OF THE DAKOTAS OVERNIGHT...SRLY WINDS WILL BEGIN TO LIFT
THE FRONT NORTH ON FRIDAY CONTINUES TO BE PROBLEMATIC AS THE LATEST
NEAR TERM MODEL SOLUTIONS ARE MUCH FARTHER SOUTH WITH THIS FEATURE
COMPARED TO YESTERDAY`S RUNS. THE LATEST MODEL RUNS PUSH THE FRONT
NORTH TO THE BLACK HILLS AND NERN NEBRASKA FRIDAY MORNING...WHICH
WILL LEAD TO ANOTHER TORCH OUT ACROSS A LARGE PORTION OF THE
FORECAST AREA ON FRIDAY. WENT AHEAD AND TRENDED TEMPS UPWARD FOR
FRIDAY...WHICH YIELDED HIGHS RANGING FROM THE MID 90S TO LOWER 100S.
VERY DRY BOUNDARY LAYER AIR WILL REMAIN IN PLACE...WHICH WILL LEAD
TO CRITICAL OR NEAR CRITICAL MINIMUM RH VALS FOR TOMORROW AFTERNOON.
THE ONE QUESTION NOW IS THE WINDS AND HOW HARD THEY WILL BLOW
FRIDAY. ATTM...THE BEST THREAT FOR GUSTS TO 25 MPH...IS ALONG AND
WEST OF HIGHWAY 83 FROM VALENTINE TO NORTH PLATTE. FURTHER
EAST...SLIGHTLY LIGHTER WINDS...WITH AN EASTERLY COMPONENT ARE
EXPECTED WHICH WILL ALSO BEGIN TO LIFT SOME BL MOISTURE FROM THE
REMNANTS OF ISAAC. WITH SOME DOUBT AS TO WHERE THE FRONT WILL STALL
TOMORROW...WILL HOIST A FIRE WEATHER WATCH FOR TOMORROW AFTERNOON
FOR ALL ZONES WITH THE EXCEPTION OF ZONE 209 WHERE WINDS WILL BE
LIGHTER.
FOR SATURDAY AND SUNDAY...FIRE THREAT IS EXPECTED TO DIMINISH
SOMEWHAT FOR SATURDAY IN THE CENTRAL AND THE EAST. IT WILL BE WARM ONCE
AGAIN WITH HIGHS IN THE LOWER TO MIDDLE 90S. HOWEVER...LOW LEVEL
MOISTURE WILL INCREASE FRIDAY NIGHT AS ISAAC LIFTS INTO MISSOURI.
FCSTED DEW POINTS SATURDAY AFTERNOON WILL RANGE FROM THE MID 40S IN
THE WEST TO AROUND 60 IN THE EAST. WITH THE EXCEPTION OF THE
WEST...SRLY WINDS WILL GENERALLY BE UNDER 15 MPH. EXTREME OR NEAR
CRITICAL FIRE DANGER LOOKS POSSIBLE IN THE WEST AND WILL CONTINUE TO
MONITOR. BY SUNDAY...A SURFACE TROUGH OF LOW PRESSURE WILL APPROACH
WESTERN AND NORTH CENTRAL NEBRASKA. EAST OF THIS FEATURE...HOT
TEMPERATURES IN THE 90S ARE LIKELY. ATTM ENOUGH RESIDUAL MOISTURE
WILL BE IN PLACE...WHICH SHOULD KEEP CRITICAL FIRE CONDS IN CHECK.
SOME WESTERN AREAS MAY BE UNDER THE GUN FOR FIRE DANGER
SUNDAY...WITH HIGHS IN THE 90S AND MINIMUM DEW POINTS IN THE LOWER
TO MID 40S.
LONG RANGE...SUNDAY NIGHT THROUGH THURSDAY...SUNDAY NIGHT THROUGH
THURSDAY. UPPER LEVEL RIDGE IS FORECASTED TO TRANSITION BACK TO THE
DESERT SOUTHWEST DURING THE PERIOD...WITH THE UPPER FLOW OVER OUR
AREA BECOMING WEST TO NORTHWEST ALOFT. SOME INCREASE IN MOISTURE IS
EXPECTED BOTH AT THE SFC AND ALOFT...AND AT LEAST A SLIGHT CHANCE
FOR SHOWERS AND THUNDERSTORMS ARE ANTICIPATED MONDAY THROUGH
WEDNESDAY AS A SERIES OF DISTURBANCES EMBEDDED WITHIN THE FLOW CROSS
THE AREA. TEMPERATURE WISE...AN OVERALL COOLING TREND BACK TO NEAR
NORMAL IS EXPECTED. HIGHS WILL RANGE FROM THE UPPER 80S MONDAY AND
TUESDAY...COOLING TO THE UPPER 70S TO MID 80S WEDNESDAY AND
THURSDAY.
FIRE WEATHER...
A LARGE FIRE IS ONGOING ACROSS NORTHWESTERN SHERIDAN COUNTY AND AN
EVACUATION ORDER HAS BEEN GIVEN FOR METCALF STATE WILDLIFE
MANAGEMENT AREA. SEE OMAEVILBF FOR DETAILS. RH WILL BEGIN TO RECOVER
TO 20 TO 30 PERCENT IN SOUTHERN AREAS AROUND 03Z THIS EVENING...SO
THE ONGOING RED FLAG WARNING WILL CONTINUE FOR ALL ZONES EXCEPT
NEZ208. ALL LOCATIONS IN THIS ZONE ARE NOW NORTH OF THE COLD
FRONT...WITH RH`S CURRENTLY RUNNING FROM 30 TO 40 PERCENT.
OVERNIGHT TONIGHT...THE COLD FRONT WILL LIFT NORTH AS A WARM
FRONT...AS HIGH PRESSURE LIFTS INTO MINNESOTA. FOR FRIDAY...A WARM
FRONT WILL BE ANCHORED FROM THE BLACK HILLS INTO NERN
NEBRASKA...WHICH WILL ALLOW THE HEAT TO BUILD NORTH INTO WESTERN AND
NORTH CENTRAL NEBRASKA FRIDAY AFTERNOON. GUSTY SRLY WINDS WILL
DEVELOP ACROSS THE CENTRAL AND WESTERN SAND HILLS...AS WELL AS THE
EASTERN NEBRASKA PANHANDLE AND SOUTHWESTERN NEBRASKA FRIDAY
AFTERNOON AND MAY GUST AS HIGH AS 25 MPH. WITH FCST DEW POINTS IN
THE 30S AND LOWER 40S FRIDAY AFTERNOON...MINIMUM RH`S OF AROUND 15
PERCENT ARE POSSIBLE. WILL BE HOISTING A FIRE WEATHER WATCH FOR
FRIDAY AFTERNOON AND EVENING FOR ALL ZONES EXCEPT 209 FOR THE
POSSIBILITY OF CRITICAL FIRE DANGER FRIDAY AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...FIRE WEATHER WATCH FROM 10 AM CDT /9 AM MDT/ THIS MORNING
THROUGH THIS EVENING FOR NEZ204-206-208-210-219.
&&
$$
SHORT TERM/EXTENDED...BUTTLER/TAYLOR
AVIATION...ROBERG
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
908 PM CDT THU AUG 30 2012
.UPDATE...
.DISCUSSION...
WINDS HAVE DECREASED WELL BELOW 25 MPH AND RELATIVE HUMIDITY HAS
RECOVERED TO OVER 20 PERCENT IN MOST AREAS. THE RED FLAG WARNING
HAS BEEN CANCELLED. A FIRE WEATHER WATCH CONTINUES FOR FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 622 PM CDT THU AUG 30 2012/
UPDATE...
AVIATION...
VFR IS EXPECTED ALL AREAS OVERNIGHT AND FRIDAY.
NO TSTMS ARE FORECAST. A COLD FRONT ACROSS NCNTL NEB THIS AFTN WILL
DRIFT SOUTH INTO THE PLATTE VALLEY THIS EVENING AND THEN RETREAT
NORTH FRIDAY AS A WARM FRONT.
PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 30 2012/
SYNOPSIS...
SURFACE ANALYSIS THIS AFTERNOON...AS A COLD FRONT EXTENDING FROM
AROUND LEWELLEN...TO ARTHUR...TO DUNNING...TO EWING. NORTH OF THIS
FEATURE...TEMPS RANGE FROM 80 AT VALENTINE...TO 94 AT O`NEILL. SOUTH
OF THE FRONT...TEMPS WERE AROUND 100 DEGREES WITH RELATIVE
HUMIDITIES RANGING FROM 5 TO 15 PERCENT. A MAJOR FIRE WAS BURNING
ACROSS NORTHWESTERN SHERIDAN COUNTY THIS AFTERNOON AT THE METCALF
STATE WILDLIFE MANAGEMENT AREA. EVACUATION ORDERS HAVE BEEN GIVEN
FOR THIS AREA OF SHERIDAN COUNTY. ADDITIONAL DETAILS ARE IN
OMAEVILBF.
ALOFT AT H5...RIDGING HAS BEGUN TO TRANSITION EAST THIS MORNING...AS
A TROUGH OF LOW PRESSURE BUILDS ALONG THE PACIFIC NW COAST. AT 12Z
THIS MORNING...ISSAC WAS LOCATED NORTHWEST OF BATON ROUGE LA.
DISCUSSION...
SHORT RANGE...TONIGHT THROUGH SUNDAY...MAIN FORECAST CHALLENGE IS
TEMPERATURES AND FIRE WEATHER CONCERNS OVER THE NEXT 24 TO 36 HRS.
FOR TONIGHT...THE LATEST NAM SOLN STALLS THE COLD FRONT ALONG
HIGHWAYS 92 AND 91 THIS EVENING...WHILE THE HIGH RES RUC PUSHES THIS
FEATURE THROUGH NORTH PLATTE TO JUST SOUTH OF INTERSTATE 80. EVEN
WITH A MORE AGGRESSIVE FRONTAL PUSH DEPICTED BY THE HI RES
RUC...LOCATIONS AHEAD OF THE FRONT HAVE ALREADY TORCHED OUT THIS
AFTERNOON WITH WIDESPREAD HIGHS WELL ABOVE THE CENTURY MARK AND
RELATIVE HUMIDITIES AS LOW AS 5 PERCENT. AS SURFACE HIGH PRESSURE
BUILDS EAST OF THE DAKOTAS OVERNIGHT...SRLY WINDS WILL BEGIN TO LIFT
THE FRONT NORTH ON FRIDAY CONTINUES TO BE PROBLEMATIC AS THE LATEST
NEAR TERM MODEL SOLUTIONS ARE MUCH FARTHER SOUTH WITH THIS FEATURE
COMPARED TO YESTERDAY`S RUNS. THE LATEST MODEL RUNS PUSH THE FRONT
NORTH TO THE BLACK HILLS AND NERN NEBRASKA FRIDAY MORNING...WHICH
WILL LEAD TO ANOTHER TORCH OUT ACROSS A LARGE PORTION OF THE
FORECAST AREA ON FRIDAY. WENT AHEAD AND TRENDED TEMPS UPWARD FOR
FRIDAY...WHICH YIELDED HIGHS RANGING FROM THE MID 90S TO LOWER 100S.
VERY DRY BOUNDARY LAYER AIR WILL REMAIN IN PLACE...WHICH WILL LEAD
TO CRITICAL OR NEAR CRITICAL MINIMUM RH VALS FOR TOMORROW AFTERNOON.
THE ONE QUESTION NOW IS THE WINDS AND HOW HARD THEY WILL BLOW
FRIDAY. ATTM...THE BEST THREAT FOR GUSTS TO 25 MPH...IS ALONG AND
WEST OF HIGHWAY 83 FROM VALENTINE TO NORTH PLATTE. FURTHER
EAST...SLIGHTLY LIGHTER WINDS...WITH AN EASTERLY COMPONENT ARE
EXPECTED WHICH WILL ALSO BEGIN TO LIFT SOME BL MOISTURE FROM THE
REMNANTS OF ISAAC. WITH SOME DOUBT AS TO WHERE THE FRONT WILL STALL
TOMORROW...WILL HOIST A FIRE WEATHER WATCH FOR TOMORROW AFTERNOON
FOR ALL ZONES WITH THE EXCEPTION OF ZONE 209 WHERE WINDS WILL BE
LIGHTER.
FOR SATURDAY AND SUNDAY...FIRE THREAT IS EXPECTED TO DIMINISH
SOMEWHAT FOR SATURDAY IN THE CENTRAL AND THE EAST. IT WILL BE WARM ONCE
AGAIN WITH HIGHS IN THE LOWER TO MIDDLE 90S. HOWEVER...LOW LEVEL
MOISTURE WILL INCREASE FRIDAY NIGHT AS ISAAC LIFTS INTO MISSOURI.
FCSTED DEW POINTS SATURDAY AFTERNOON WILL RANGE FROM THE MID 40S IN
THE WEST TO AROUND 60 IN THE EAST. WITH THE EXCEPTION OF THE
WEST...SRLY WINDS WILL GENERALLY BE UNDER 15 MPH. EXTREME OR NEAR
CRITICAL FIRE DANGER LOOKS POSSIBLE IN THE WEST AND WILL CONTINUE TO
MONITOR. BY SUNDAY...A SURFACE TROUGH OF LOW PRESSURE WILL APPROACH
WESTERN AND NORTH CENTRAL NEBRASKA. EAST OF THIS FEATURE...HOT
TEMPERATURES IN THE 90S ARE LIKELY. ATTM ENOUGH RESIDUAL MOISTURE
WILL BE IN PLACE...WHICH SHOULD KEEP CRITICAL FIRE CONDS IN CHECK.
SOME WESTERN AREAS MAY BE UNDER THE GUN FOR FIRE DANGER
SUNDAY...WITH HIGHS IN THE 90S AND MINIMUM DEW POINTS IN THE LOWER
TO MID 40S.
LONG RANGE...SUNDAY NIGHT THROUGH THURSDAY...SUNDAY NIGHT THROUGH
THURSDAY. UPPER LEVEL RIDGE IS FORECASTED TO TRANSITION BACK TO THE
DESERT SOUTHWEST DURING THE PERIOD...WITH THE UPPER FLOW OVER OUR
AREA BECOMING WEST TO NORTHWEST ALOFT. SOME INCREASE IN MOISTURE IS
EXPECTED BOTH AT THE SFC AND ALOFT...AND AT LEAST A SLIGHT CHANCE
FOR SHOWERS AND THUNDERSTORMS ARE ANTICIPATED MONDAY THROUGH
WEDNESDAY AS A SERIES OF DISTURBANCES EMBEDDED WITHIN THE FLOW CROSS
THE AREA. TEMPERATURE WISE...AN OVERALL COOLING TREND BACK TO NEAR
NORMAL IS EXPECTED. HIGHS WILL RANGE FROM THE UPPER 80S MONDAY AND
TUESDAY...COOLING TO THE UPPER 70S TO MID 80S WEDNESDAY AND
THURSDAY.
AVIATION...A COLD FRONT WILL STALL FROM NEAR KBUB TO KSNY THIS
AFTERNOON. TO THE NORTH OF THE FRONT...SFC WINDS WILL NE NORTH TO
NORTHEAST AT 5 TO 15 KTS...WHILE SOUTHWEST WINDS WILL CONTINUE AT 10
TO 20 KTS TO THE SOUTH OF THE FRONT. BROKEN MID LEVEL CEILINGS AND
FEW LIGHT RAIN SHOWERS ARE POSSIBLE TO THE NORTH OF THE FRONT
THROUGH LATE THIS AFTERNOON.
FIRE WEATHER...
A LARGE FIRE IS ONGOING ACROSS NORTHWESTERN SHERIDAN COUNTY AND AN
EVACUATION ORDER HAS BEEN GIVEN FOR METCALF STATE WILDLIFE
MANAGEMENT AREA. SEE OMAEVILBF FOR DETAILS. RH WILL BEGIN TO RECOVER
TO 20 TO 30 PERCENT IN SOUTHERN AREAS AROUND 03Z THIS EVENING...SO
THE ONGOING RED FLAG WARNING WILL CONTINUE FOR ALL ZONES EXCEPT
NEZ208. ALL LOCATIONS IN THIS ZONE ARE NOW NORTH OF THE COLD
FRONT...WITH RH`S CURRENTLY RUNNING FROM 30 TO 40 PERCENT.
OVERNIGHT TONIGHT...THE COLD FRONT WILL LIFT NORTH AS A WARM
FRONT...AS HIGH PRESSURE LIFTS INTO MINNESOTA. FOR FRIDAY...A WARM
FRONT WILL BE ANCHORED FROM THE BLACK HILLS INTO NERN
NEBRASKA...WHICH WILL ALLOW THE HEAT TO BUILD NORTH INTO WESTERN AND
NORTH CENTRAL NEBRASKA FRIDAY AFTERNOON. GUSTY SRLY WINDS WILL
DEVELOP ACROSS THE CENTRAL AND WESTERN SAND HILLS...AS WELL AS THE
EASTERN NEBRASKA PANHANDLE AND SOUTHWESTERN NEBRASKA FRIDAY
AFTERNOON AND MAY GUST AS HIGH AS 25 MPH. WITH FCST DEW POINTS IN
THE 30S AND LOWER 40S FRIDAY AFTERNOON...MINIMUM RH`S OF AROUND 15
PERCENT ARE POSSIBLE. WILL BE HOISTING A FIRE WEATHER WATCH FOR
FRIDAY AFTERNOON AND EVENING FOR ALL ZONES EXCEPT 209 FOR THE
POSSIBILITY OF CRITICAL FIRE DANGER FRIDAY AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...FIRE WEATHER WATCH FROM FRIDAY MORNING
THROUGH FRIDAY EVENING FOR NEZ204-206-208-210-219.
&&
$$
SHORT TERM/EXTENDED...JACOBS
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
622 PM CDT THU AUG 30 2012
.UPDATE...
.AVIATION...
VFR IS EXPECTED ALL AREAS OVERNIGHT AND FRIDAY.
NO TSTMS ARE FORECAST. A COLD FRONT ACROSS NCNTL NEB THIS AFTN WILL
DRIFT SOUTH INTO THE PLATTE VALLEY THIS EVENING AND THEN RETREAT
NORTH FRIDAY AS A WARM FRONT.
&&
.PREV DISCUSSION... /ISSUED 350 PM CDT THU AUG 30 2012/
SYNOPSIS...
SURFACE ANALYSIS THIS AFTERNOON...AS A COLD FRONT EXTENDING FROM
AROUND LEWELLEN...TO ARTHUR...TO DUNNING...TO EWING. NORTH OF THIS
FEATURE...TEMPS RANGE FROM 80 AT VALENTINE...TO 94 AT O`NEILL. SOUTH
OF THE FRONT...TEMPS WERE AROUND 100 DEGREES WITH RELATIVE
HUMIDITIES RANGING FROM 5 TO 15 PERCENT. A MAJOR FIRE WAS BURNING
ACROSS NORTHWESTERN SHERIDAN COUNTY THIS AFTERNOON AT THE METCALF
STATE WILDLIFE MANAGEMENT AREA. EVACUATION ORDERS HAVE BEEN GIVEN
FOR THIS AREA OF SHERIDAN COUNTY. ADDITIONAL DETAILS ARE IN
OMAEVILBF.
ALOFT AT H5...RIDGING HAS BEGUN TO TRANSITION EAST THIS MORNING...AS
A TROUGH OF LOW PRESSURE BUILDS ALONG THE PACIFIC NW COAST. AT 12Z
THIS MORNING...ISSAC WAS LOCATED NORTHWEST OF BATON ROUGE LA.
DISCUSSION...
SHORT RANGE...TONIGHT THROUGH SUNDAY...MAIN FORECAST CHALLENGE IS
TEMPERATURES AND FIRE WEATHER CONCERNS OVER THE NEXT 24 TO 36 HRS.
FOR TONIGHT...THE LATEST NAM SOLN STALLS THE COLD FRONT ALONG
HIGHWAYS 92 AND 91 THIS EVENING...WHILE THE HIGH RES RUC PUSHES THIS
FEATURE THROUGH NORTH PLATTE TO JUST SOUTH OF INTERSTATE 80. EVEN
WITH A MORE AGGRESSIVE FRONTAL PUSH DEPICTED BY THE HI RES
RUC...LOCATIONS AHEAD OF THE FRONT HAVE ALREADY TORCHED OUT THIS
AFTERNOON WITH WIDESPREAD HIGHS WELL ABOVE THE CENTURY MARK AND
RELATIVE HUMIDITIES AS LOW AS 5 PERCENT. AS SURFACE HIGH PRESSURE
BUILDS EAST OF THE DAKOTAS OVERNIGHT...SRLY WINDS WILL BEGIN TO LIFT
THE FRONT NORTH ON FRIDAY CONTINUES TO BE PROBLEMATIC AS THE LATEST
NEAR TERM MODEL SOLUTIONS ARE MUCH FARTHER SOUTH WITH THIS FEATURE
COMPARED TO YESTERDAY`S RUNS. THE LATEST MODEL RUNS PUSH THE FRONT
NORTH TO THE BLACK HILLS AND NERN NEBRASKA FRIDAY MORNING...WHICH
WILL LEAD TO ANOTHER TORCH OUT ACROSS A LARGE PORTION OF THE
FORECAST AREA ON FRIDAY. WENT AHEAD AND TRENDED TEMPS UPWARD FOR
FRIDAY...WHICH YIELDED HIGHS RANGING FROM THE MID 90S TO LOWER 100S.
VERY DRY BOUNDARY LAYER AIR WILL REMAIN IN PLACE...WHICH WILL LEAD
TO CRITICAL OR NEAR CRITICAL MINIMUM RH VALS FOR TOMORROW AFTERNOON.
THE ONE QUESTION NOW IS THE WINDS AND HOW HARD THEY WILL BLOW
FRIDAY. ATTM...THE BEST THREAT FOR GUSTS TO 25 MPH...IS ALONG AND
WEST OF HIGHWAY 83 FROM VALENTINE TO NORTH PLATTE. FURTHER
EAST...SLIGHTLY LIGHTER WINDS...WITH AN EASTERLY COMPONENT ARE
EXPECTED WHICH WILL ALSO BEGIN TO LIFT SOME BL MOISTURE FROM THE
REMNANTS OF ISAAC. WITH SOME DOUBT AS TO WHERE THE FRONT WILL STALL
TOMORROW...WILL HOIST A FIRE WEATHER WATCH FOR TOMORROW AFTERNOON
FOR ALL ZONES WITH THE EXCEPTION OF ZONE 209 WHERE WINDS WILL BE
LIGHTER.
FOR SATURDAY AND SUNDAY...FIRE THREAT IS EXPECTED TO DIMINISH
SOMEWHAT FOR SATURDAY IN THE CENTRAL AND THE EAST. IT WILL BE WARM ONCE
AGAIN WITH HIGHS IN THE LOWER TO MIDDLE 90S. HOWEVER...LOW LEVEL
MOISTURE WILL INCREASE FRIDAY NIGHT AS ISAAC LIFTS INTO MISSOURI.
FCSTED DEW POINTS SATURDAY AFTERNOON WILL RANGE FROM THE MID 40S IN
THE WEST TO AROUND 60 IN THE EAST. WITH THE EXCEPTION OF THE
WEST...SRLY WINDS WILL GENERALLY BE UNDER 15 MPH. EXTREME OR NEAR
CRITICAL FIRE DANGER LOOKS POSSIBLE IN THE WEST AND WILL CONTINUE TO
MONITOR. BY SUNDAY...A SURFACE TROUGH OF LOW PRESSURE WILL APPROACH
WESTERN AND NORTH CENTRAL NEBRASKA. EAST OF THIS FEATURE...HOT
TEMPERATURES IN THE 90S ARE LIKELY. ATTM ENOUGH RESIDUAL MOISTURE
WILL BE IN PLACE...WHICH SHOULD KEEP CRITICAL FIRE CONDS IN CHECK.
SOME WESTERN AREAS MAY BE UNDER THE GUN FOR FIRE DANGER
SUNDAY...WITH HIGHS IN THE 90S AND MINIMUM DEW POINTS IN THE LOWER
TO MID 40S.
LONG RANGE...SUNDAY NIGHT THROUGH THURSDAY...SUNDAY NIGHT THROUGH
THURSDAY. UPPER LEVEL RIDGE IS FORECASTED TO TRANSITION BACK TO THE
DESERT SOUTHWEST DURING THE PERIOD...WITH THE UPPER FLOW OVER OUR
AREA BECOMING WEST TO NORTHWEST ALOFT. SOME INCREASE IN MOISTURE IS
EXPECTED BOTH AT THE SFC AND ALOFT...AND AT LEAST A SLIGHT CHANCE
FOR SHOWERS AND THUNDERSTORMS ARE ANTICIPATED MONDAY THROUGH
WEDNESDAY AS A SERIES OF DISTURBANCES EMBEDDED WITHIN THE FLOW CROSS
THE AREA. TEMPERATURE WISE...AN OVERALL COOLING TREND BACK TO NEAR
NORMAL IS EXPECTED. HIGHS WILL RANGE FROM THE UPPER 80S MONDAY AND
TUESDAY...COOLING TO THE UPPER 70S TO MID 80S WEDNESDAY AND
THURSDAY.
AVIATION...A COLD FRONT WILL STALL FROM NEAR KBUB TO KSNY THIS
AFTERNOON. TO THE NORTH OF THE FRONT...SFC WINDS WILL NE NORTH TO
NORTHEAST AT 5 TO 15 KTS...WHILE SOUTHWEST WINDS WILL CONTINUE AT 10
TO 20 KTS TO THE SOUTH OF THE FRONT. BROKEN MID LEVEL CEILINGS AND
FEW LIGHT RAIN SHOWERS ARE POSSIBLE TO THE NORTH OF THE FRONT
THROUGH LATE THIS AFTERNOON.
FIRE WEATHER...
A LARGE FIRE IS ONGOING ACROSS NORTHWESTERN SHERIDAN COUNTY AND AN
EVACUATION ORDER HAS BEEN GIVEN FOR METCALF STATE WILDLIFE
MANAGEMENT AREA. SEE OMAEVILBF FOR DETAILS. RH WILL BEGIN TO RECOVER
TO 20 TO 30 PERCENT IN SOUTHERN AREAS AROUND 03Z THIS EVENING...SO
THE ONGOING RED FLAG WARNING WILL CONTINUE FOR ALL ZONES EXCEPT
NEZ208. ALL LOCATIONS IN THIS ZONE ARE NOW NORTH OF THE COLD
FRONT...WITH RH`S CURRENTLY RUNNING FROM 30 TO 40 PERCENT.
OVERNIGHT TONIGHT...THE COLD FRONT WILL LIFT NORTH AS A WARM
FRONT...AS HIGH PRESSURE LIFTS INTO MINNESOTA. FOR FRIDAY...A WARM
FRONT WILL BE ANCHORED FROM THE BLACK HILLS INTO NERN
NEBRASKA...WHICH WILL ALLOW THE HEAT TO BUILD NORTH INTO WESTERN AND
NORTH CENTRAL NEBRASKA FRIDAY AFTERNOON. GUSTY SRLY WINDS WILL
DEVELOP ACROSS THE CENTRAL AND WESTERN SAND HILLS...AS WELL AS THE
EASTERN NEBRASKA PANHANDLE AND SOUTHWESTERN NEBRASKA FRIDAY
AFTERNOON AND MAY GUST AS HIGH AS 25 MPH. WITH FCST DEW POINTS IN
THE 30S AND LOWER 40S FRIDAY AFTERNOON...MINIMUM RH`S OF AROUND 15
PERCENT ARE POSSIBLE. WILL BE HOISTING A FIRE WEATHER WATCH FOR
FRIDAY AFTERNOON AND EVENING FOR ALL ZONES EXCEPT 209 FOR THE
POSSIBILITY OF CRITICAL FIRE DANGER FRIDAY AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 11 PM CDT /10 PM MDT/ THIS EVENING FOR
NEZ204-206-209-210-219.
FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR NEZ204-206-208-210-219.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CLB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
350 PM CDT THU AUG 30 2012
.SYNOPSIS...
SURFACE ANALYSIS THIS AFTERNOON...AS A COLD FRONT EXTENDING FROM
AROUND LEWELLEN...TO ARTHUR...TO DUNNING...TO EWING. NORTH OF THIS
FEATURE...TEMPS RANGE FROM 80 AT VALENTINE...TO 94 AT O`NEILL. SOUTH
OF THE FRONT...TEMPS WERE AROUND 100 DEGREES WITH RELATIVE
HUMIDITIES RANGING FROM 5 TO 15 PERCENT. A MAJOR FIRE WAS BURNING
ACROSS NORTHWESTERN SHERIDAN COUNTY THIS AFTERNOON AT THE METCALF
STATE WILDLIFE MANAGEMENT AREA. EVACUATION ORDERS HAVE BEEN GIVEN
FOR THIS AREA OF SHERIDAN COUNTY. ADDITIONAL DETAILS ARE IN
OMAEVILBF.
ALOFT AT H5...RIDGING HAS BEGUN TO TRANSITION EAST THIS MORNING...AS
A TROUGH OF LOW PRESSURE BUILDS ALONG THE PACIFIC NW COAST. AT 12Z
THIS MORNING...ISSAC WAS LOCATED NORTHWEST OF BATON ROUGE LA.
&&
.DISCUSSION...
SHORT RANGE...TONIGHT THROUGH SUNDAY...MAIN FORECAST CHALLENGE IS
TEMPERATURES AND FIRE WEATHER CONCERNS OVER THE NEXT 24 TO 36 HRS.
FOR TONIGHT...THE LATEST NAM SOLN STALLS THE COLD FRONT ALONG
HIGHWAYS 92 AND 91 THIS EVENING...WHILE THE HIGH RES RUC PUSHES THIS
FEATURE THROUGH NORTH PLATTE TO JUST SOUTH OF INTERSTATE 80. EVEN
WITH A MORE AGGRESSIVE FRONTAL PUSH DEPICTED BY THE HI RES
RUC...LOCATIONS AHEAD OF THE FRONT HAVE ALREADY TORCHED OUT THIS
AFTERNOON WITH WIDESPREAD HIGHS WELL ABOVE THE CENTURY MARK AND
RELATIVE HUMIDITIES AS LOW AS 5 PERCENT. AS SURFACE HIGH PRESSURE
BUILDS EAST OF THE DAKOTAS OVERNIGHT...SRLY WINDS WILL BEGIN TO LIFT
THE FRONT NORTH ON FRIDAY CONTINUES TO BE PROBLEMATIC AS THE LATEST
NEAR TERM MODEL SOLUTIONS ARE MUCH FARTHER SOUTH WITH THIS FEATURE
COMPARED TO YESTERDAY`S RUNS. THE LATEST MODEL RUNS PUSH THE FRONT
NORTH TO THE BLACK HILLS AND NERN NEBRASKA FRIDAY MORNING...WHICH
WILL LEAD TO ANOTHER TORCH OUT ACROSS A LARGE PORTION OF THE
FORECAST AREA ON FRIDAY. WENT AHEAD AND TRENDED TEMPS UPWARD FOR
FRIDAY...WHICH YIELDED HIGHS RANGING FROM THE MID 90S TO LOWER 100S.
VERY DRY BOUNDARY LAYER AIR WILL REMAIN IN PLACE...WHICH WILL LEAD
TO CRITICAL OR NEAR CRITICAL MINIMUM RH VALS FOR TOMORROW AFTERNOON.
THE ONE QUESTION NOW IS THE WINDS AND HOW HARD THEY WILL BLOW
FRIDAY. ATTM...THE BEST THREAT FOR GUSTS TO 25 MPH...IS ALONG AND
WEST OF HIGHWAY 83 FROM VALENTINE TO NORTH PLATTE. FURTHER
EAST...SLIGHTLY LIGHTER WINDS...WITH AN EASTERLY COMPONENT ARE
EXPECTED WHICH WILL ALSO BEGIN TO LIFT SOME BL MOISTURE FROM THE
REMNANTS OF ISAAC. WITH SOME DOUBT AS TO WHERE THE FRONT WILL STALL
TOMORROW...WILL HOIST A FIRE WEATHER WATCH FOR TOMORROW AFTERNOON
FOR ALL ZONES WITH THE EXCEPTION OF ZONE 209 WHERE WINDS WILL BE
LIGHTER.
FOR SATURDAY AND SUNDAY...FIRE THREAT IS EXPECTED TO DIMINISH
SOMEWHAT FOR SATURDAY IN THE CENTRAL AND THE EAST. IT WILL BE WARM ONCE
AGAIN WITH HIGHS IN THE LOWER TO MIDDLE 90S. HOWEVER...LOW LEVEL
MOISTURE WILL INCREASE FRIDAY NIGHT AS ISAAC LIFTS INTO MISSOURI.
FCSTED DEW POINTS SATURDAY AFTERNOON WILL RANGE FROM THE MID 40S IN
THE WEST TO AROUND 60 IN THE EAST. WITH THE EXCEPTION OF THE
WEST...SRLY WINDS WILL GENERALLY BE UNDER 15 MPH. EXTREME OR NEAR
CRITICAL FIRE DANGER LOOKS POSSIBLE IN THE WEST AND WILL CONTINUE TO
MONITOR. BY SUNDAY...A SURFACE TROUGH OF LOW PRESSURE WILL APPROACH
WESTERN AND NORTH CENTRAL NEBRASKA. EAST OF THIS FEATURE...HOT
TEMPERATURES IN THE 90S ARE LIKELY. ATTM ENOUGH RESIDUAL MOISTURE
WILL BE IN PLACE...WHICH SHOULD KEEP CRITICAL FIRE CONDS IN CHECK.
SOME WESTERN AREAS MAY BE UNDER THE GUN FOR FIRE DANGER
SUNDAY...WITH HIGHS IN THE 90S AND MINIMUM DEW POINTS IN THE LOWER
TO MID 40S.
LONG RANGE...SUNDAY NIGHT THROUGH THURSDAY...SUNDAY NIGHT THROUGH
THURSDAY. UPPER LEVEL RIDGE IS FORECASTED TO TRANSITION BACK TO THE
DESERT SOUTHWEST DURING THE PERIOD...WITH THE UPPER FLOW OVER OUR
AREA BECOMING WEST TO NORTHWEST ALOFT. SOME INCREASE IN MOISTURE IS
EXPECTED BOTH AT THE SFC AND ALOFT...AND AT LEAST A SLIGHT CHANCE
FOR SHOWERS AND THUNDERSTORMS ARE ANTICIPATED MONDAY THROUGH
WEDNESDAY AS A SERIES OF DISTURBANCES EMBEDDED WITHIN THE FLOW CROSS
THE AREA. TEMPERATURE WISE...AN OVERALL COOLING TREND BACK TO NEAR
NORMAL IS EXPECTED. HIGHS WILL RANGE FROM THE UPPER 80S MONDAY AND
TUESDAY...COOLING TO THE UPPER 70S TO MID 80S WEDNESDAY AND
THURSDAY.
&&
.AVIATION...A COLD FRONT WILL STALL FROM NEAR KBUB TO KSNY THIS
AFTERNOON. TO THE NORTH OF THE FRONT...SFC WINDS WILL NE NORTH TO
NORTHEAST AT 5 TO 15 KTS...WHILE SOUTHWEST WINDS WILL CONTINUE AT 10
TO 20 KTS TO THE SOUTH OF THE FRONT. BROKEN MID LEVEL CEILINGS AND
FEW LIGHT RAIN SHOWERS ARE POSSIBLE TO THE NORTH OF THE FRONT
THROUGH LATE THIS AFTERNOON.
&&
.FIRE WEATHER...
A LARGE FIRE IS ONGOING ACROSS NORTHWESTERN SHERIDAN COUNTY AND AN
EVACUATION ORDER HAS BEEN GIVEN FOR METCALF STATE WILDLIFE
MANAGEMENT AREA. SEE OMAEVILBF FOR DETAILS. RH WILL BEGIN TO RECOVER
TO 20 TO 30 PERCENT IN SOUTHERN AREAS AROUND 03Z THIS EVENING...SO
THE ONGOING RED FLAG WARNING WILL CONTINUE FOR ALL ZONES EXCEPT
NEZ208. ALL LOCATIONS IN THIS ZONE ARE NOW NORTH OF THE COLD
FRONT...WITH RH`S CURRENTLY RUNNING FROM 30 TO 40 PERCENT.
OVERNIGHT TONIGHT...THE COLD FRONT WILL LIFT NORTH AS A WARM
FRONT...AS HIGH PRESSURE LIFTS INTO MINNESOTA. FOR FRIDAY...A WARM
FRONT WILL BE ANCHORED FROM THE BLACK HILLS INTO NERN
NEBRASKA...WHICH WILL ALLOW THE HEAT TO BUILD NORTH INTO WESTERN AND
NORTH CENTRAL NEBRASKA FRIDAY AFTERNOON. GUSTY SRLY WINDS WILL
DEVELOP ACROSS THE CENTRAL AND WESTERN SAND HILLS...AS WELL AS THE
EASTERN NEBRASKA PANHANDLE AND SOUTHWESTERN NEBRASKA FRIDAY
AFTERNOON AND MAY GUST AS HIGH AS 25 MPH. WITH FCST DEW POINTS IN
THE 30S AND LOWER 40S FRIDAY AFTERNOON...MINIMUM RH`S OF AROUND 15
PERCENT ARE POSSIBLE. WILL BE HOISTING A FIRE WEATHER WATCH FOR
FRIDAY AFTERNOON AND EVENING FOR ALL ZONES EXCEPT 209 FOR THE
POSSIBILITY OF CRITICAL FIRE DANGER FRIDAY AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING THROUGH 11 PM
CDT (10 PM MDT) TONIGHT FOR ZONES NEZ204-206-209-210-219.
FIRE WEATHER WATCH FROM 10 AM CDT (9 AM MDT) THROUGH 11 PM CDT (10
PM MDT) FRIDAY FOR ZONES NEZ204-206-208-210-219.
$$
SYNOPSIS...SHORT AND FIRE WEATHER...BUTTLER
AVIATION AND LONG RANGE...TAYLOR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
355 PM EDT FRI AUG 31 2012
.SYNOPSIS...
A COLD FRONT WILL DROP SOUTH ACROSS THE AREA OVERNIGHT WITH NO MORE
THAN ISOLATED SHOWERS AND THUNDERSTORMS ACROSS NORTHERN NEW YORK.
HIGH PRESSURE WILL RETURN BEHIND THE FRONT WITH MORE SEASONABLE
TEMPERATURES FOR THE WEEKEND. THE NEXT CHANCE FOR RAIN WILL BE EARLY
NEXT WEEK WHEN THE REMNANTS OF ISSAC WILL POTENTIALLY IMPACT THE
REGION.
&&
.NEAR TERM /THROUGH SATURDAY/...
SURFACE ANALYSIS ALONG WITH RADAR AND SATELLITE IMAGERY REVEAL A
COLD FRONT ORIENTED EAST TO WEST ACROSS SOUTHERN QUEBEC AND ONTARIO
PROVINCES JUST NORTH OF OTTAWA AT 19Z. KTYX NWS DOPPLER AND THE
CANADIAN RADAR NEAR MONTREAL SHOW A BAND OF THUNDERSTORMS ORIENTED
ALONG THE FRONT WITH ANOTHER AREA OF THUNDERSTORMS BETWEEN MONTREAL
QUEBEC AND MASSENA NEW YORK. A TIGHT PRESSURE GRADIENT EXISTS ACROSS
NEW YORK SOUTH OF THE FRONT AS IT SLOWLY SQUEEZES SOUTH TOWARD A
SURFACE HIGH OVER THE MID ATLANTIC. THIS IS CREATING GUSTY SOUTHWEST
WINDS ACROSS THE FORECAST AREA AVERAGING 20 TO 30 MPH.
HIGH RESOLUTION MODEL DATA INCLUDING THE 17Z HRRR AND LATEST NMM/ARW
WRF RUNS INDICATE INCREASING CONVECTION FORMING AHEAD OF AND ALONG
THE FRONT INTO THE EARLY EVENING AS IT PRESSES FURTHER SOUTHWARD
TOWARD NORTHERN NY. THE BIG QUESTION IS WHETHER ENOUGH LOW LEVEL
MOISTURE WILL BE AVAILABLE ACROSS NORTHERN NY AND IF SURFACE
INSTABILITY CAN OVERCOME THE MID LEVEL HEAT RIDGE BUILDING NORTH
ACROSS CENTRAL NEW YORK. WHILE SURFACE MOISTURE IS LIMITED WITH
DEWPOINT DEPRESSIONS OF AROUND 15F...SOME MID LEVEL MOISTURE IS
AVAILABLE...SPC MESOANALYSIS DATA SHOWING 1.5 TO 1.8 INCHES OF
PRECIPITABLE WATER EAST OF LAKE ONTARIO. MESOANALYSIS ALSO REVEALS A
CAP IN PLACE ACROSS THE FORECAST AREA WITH THE ONLY UNCAPPED AREA
WITH SOME CAPE BEING NEAR OTTAWA. WIND SHEAR HOWEVER IS HIGH WITH
MESOANALYSIS INDICATING 0-6 KM SHEAR RUNNING GREATER THAN 50 KTS. IF
SIGNIFICANT STORM UPDRAFTS CAN DEVELOP SOUTH INTO THE EASTERN LAKE
ONTARIO REGION IT APPEARS THAT DAMAGING WINDS WOULD BE THE MAIN
SEVERE WEATHER THREAT WITH THE STRONGEST CELLS. SPC HAS INCLUDED
PARTS OF THE EASTERN LAKE ONTARIO REGION IN A SLIGHT RISK FOR SEVERE
STORMS.
TONIGHT...WIND GUSTS ARE FORECAST TO FALL OFF NEAR SUNSET WITH
SUSTAINED WINDS OF AROUND 10 MPH FINALLY LOWERING WHEN THE SURFACE
FRONT SHIFTS SOUTH OF THE AREA. COOLER TEMPERATURES WILL ADVECT INTO
THE REGION WITH MAINLY CLEAR SKIES. OVERNIGHT LOWS FORECASTED A BIT
WARMER BASED ON 12Z MODEL GUIDANCE AND HIGH TEMPS REACHED TODAY
FALLING INTO THE 60S. NORTHERLY FLOW SETTING UP BEHIND THE FRONT MAY
HOLD THE LAKE PLAIN AREAS A LITTLE WARMER. MOS GUIDANCE AND BUFKIT
PROFILES INDICATE PATCHY FOG ALSO POSSIBLE TONIGHT MOST LIKELY IN
SHELTERED AREAS AFTER THE WINDS FALL OFF. CLEAR SKIES SHOULD PROVIDE
GREAT RADIATIONAL COOLING BUT WINDS WILL BE THE QUESTION.
ON SATURDAY HIGH PRESSURE OVER MINNESOTA THIS EVENING WILL SHIFT
EASTWARD AND BUILD IN BEHIND THE FRONT. EXPECT MAINLY CLEAR SKIES
WITH LIGHT NORTHERLY WINDS AND SEASONABLE TEMPERATURES RUNNING IN
THE UPPER 70S TO LOW 80S...A FINE LATE SUMMER DAY!
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
HIGH PRESSURE ACROSS THE UPPER LAKES SATURDAY EVENING WILL SHIFT
TO NORTHERN NEW ENGLAND THROUGH SUNDAY NIGHT. IT STILL APPEARS THIS
HIGH WILL KEEP MOISTURE ASSOCIATED WITH THE REMNANTS OF ISAAC TO OUR
SOUTH AND WEST.
EXPECT SUNDAY TO BE A QUITE PLEASANT DAY ACROSS WESTERN NEW
YORK...WITH SEASONABLE TEMPERATURES IN THE UPPER 70S AND LOWER 80S.
THERE WILL BE QUITE A BIT OF SUNSHINE ACROSS MOST OF THE
REGION...WITH CLOUDS A BIT MORE PREVALENT IN THE SOUTHERN TIER. THERE
MAY BE SCATTERED SHOWERS TO OUR SOUTH...BUT A PRETTY STRONG MODEL
CONSENSUS KEEPS THIS OUT OF OUR REGION ON THE STRENGTH OF THE HIGH
POSITIONED TO OUR NORTH.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
12Z MODEL CONSENSUS HAS SLOWED A BIT WITH THE APPROACH OF MOISTURE
FROM THE TROPICAL REMNANTS OF ISAAC. PART OF THIS IS THAT MODEL
GUIDANCE HAS BEEN TRENDING TOWARD A WEAKER SHORTWAVE EARLY NEXT
WEEK...WHICH ALSO SLOWS AND WEAKENS THE APPROACH OF AN ASSOCIATED
FRONTAL BOUNDARY. WHILE THE MAJORITY OF MODELS (GFS/EUROPEAN) BRING
SHOWERS AND THUNDERSTORMS INTO WESTERN NEW YORK ON MONDAY...THE GGEM
IS A LARGELY DRY FORECAST.
WITH THIS TREND IN MIND...EXPECT THE STEADIEST RAINS TO COME DURING
THE LATTER HALF OF MONDAY NIGHT THROUGH TUESDAY MORNING...WITH THIS
AXIS LIKELY TO SHIFT INTO EASTERN PORTIONS OF THE CWA TUESDAY
AFTERNOON. OUTSIDE OF THE SLIGHTLY SLOWER TIMING...OUR EXPECTATION
OF RAINFALL AVERAGING AROUND AN INCH REMAINS THE SAME. MODEL
GUIDANCE HAS BEEN INCONSISTENT ON QPF...WITH THE 12Z GFS IN
PARTICULAR LIKELY OVERDONE IN A CONVECTIVE BULLSEYE IN WESTERN
PORTIONS OF THE SOUTHERN TIER. THE GGEM/EUROPEAN ARE BOTH MUCH MORE
IN LINE WITH PREVIOUS CONSENSUS...THOUGH IT SHOULD BE NOTED THAT
LOCALLY HIGHER...AND LOWER...AMOUNTS ARE EXPECTED. IT IS SIMPLY TOO
FAR OFF TO PIN SPECIFICS DOWN. WHILE RAINFALL AMOUNTS WILL VARY...AN
INCH OF RAIN WOULD BE BENEFICIAL FOR AREAS IMPACTED BY THE DROUGHT.
THE POTENTIAL FOR FLOODING REMAIN LOW FOR WESTERN NEW YORK...WITH
THE ONLY REAL THREAT COMING FROM LOCALIZED OR SLOW MOVING CONVECTIVE
CELLS.
THE SHORTWAVE AND ASSOCIATED FRONTAL BOUNDARY WILL EXIT TO THE EAST
TUESDAY NIGHT...WITH THE REGION LIKELY TO END UP BETWEEN SYSTEMS
WEDNESDAY. THEN A DEEPER SHORTWAVE WILL APPROACH...WITH A BLEND OF
THE GFS/EUROPEAN BRINGING THIS ACROSS WEDNESDAY NIGHT OR THURSDAY.
THIS FRONT SUPPORTS CHANCE POPS FOR NOW.
BOTH THE 12Z GFS/EUROPEAN EXIT THIS FRONT TO THE EAST...WITH DRY
WEATHER LIKELY FOR FRIDAY. THE GFS IS QUITE A BIT COOLER THAN THE
EUROPEAN...WITH OUR FORECAST A BLEND BETWEEN THE TWO.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
MAINLY VFR CONDITIONS EXPECTED THROUGH THE 18Z TAF CYCLE EXCEPT FOR
SOME FOG DEVELOPING ACROSS THE SOUTHERN TIER WHICH MAY IMPACT KJHW.
THIS EVENING A COLD FRONT LOCATED JUST NORTH OF THE NY/CANADIAN
BORDER WILL DRIFT SOUTH ACROSS THE STATE. ONLY ISOLATED SHOWERS OR
THUNDERSTORMS COULD DEVELOP ACROSS NORTHERN NEW YORK EARLY THIS
AHEAD OF THE FRONT.
WINDS WILL BE THE MAIN ISSUE EARLY THIS EVENING WITH GUSTS STILL
RUNNING 25 TO 35 KTS AT 19Z. HIGHEST WIND ISSUES WILL BE ACROSS THE
NIAGARA FRONTIER AS THE SOUTHWEST WINDS FUNNEL ALONG LAKE ERIE. WIND
GUSTS WILL FALL OFF NEAR SUNSET WITH THE END OF MIXING. SUSTAINED
WINDS WILL THEN FALL OFF INTO THE LATE EVENING AFTER THE COLD FRONT
DROPS SOUTH.
LATE TONIGHT MOS AND LAMP GUIDANCE INDICATE POTENTIAL FOR FOG AT
KJHW. WHILE GUIDANCE IS GOING AS LOW AS LIFR OPTED TO KEEP VIS DOWN
TO ONLY 2SM FOR NOW. THE ISSUE WHICH MAY PREVENT THIS WOULD BE WINDS
REMAINING TOO HIGH LATE TONIGHT. VFR SATURDAY UNDER HIGH PRESSURE.
OUTLOOK...
SATURDAY THROUGH SUNDAY...VFR.
MONDAY...LIKELY RAIN SHOWERS DETERIORATING TO MVFR.
MONDAY NIGHT AND TUESDAY...MVFR/IFR IN RAIN SHOWERS LIKELY MONDAY
NIGHT...AND POSSIBLY ON TUESDAY.
&&
.MARINE...
A COLD FRONT DROPPING SOUTHWARD FROM CANADA HAS TIGHTEN THE PRESSURE
GRADIENT OVER THE LOWER GREAT LAKES REGION THIS AFTERNOON AND
EVENING AS IT RUNS INTO A HIGH PRESSURE SYSTEM OVER THE
MID-ATLANTIC. SOUTHWEST WINDS AND WAVES HAVE REACHED SMALL CRAFT
ADVISORY CRITERIA TODAY AHEAD OF THE FRONT. SMALL CRAFTS REMAIN IN
EFFECT FOR ALL MARINE ZONES EXCEPT THE LOWER NIAGARA AND ST.
LAWRENCE RIVER. BEHIND THE FRONT...WINDS WILL SHIFT TO LIGHT
NORTHERLY AND WAVE HEIGHTS WILL EVENTUALLY SUBSIDE OVER THE LAKES.
HIGH PRESSURE WILL THEN BUILD ACROSS THE REGION SATURDAY...RESULTING
IN FINE BOATING WEATHER FOR THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ020.
SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LOZ042-043.
SMALL CRAFT ADVISORY UNTIL 1 AM EDT SATURDAY FOR LOZ045.
SMALL CRAFT ADVISORY UNTIL 3 AM EDT SATURDAY FOR LOZ044.
&&
$$
SYNOPSIS...SMITH
NEAR TERM...SMITH
SHORT TERM...APFFEL
LONG TERM...APFFEL
AVIATION...SMITH
MARINE...APFFEL/SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
144 AM EDT FRI AUG 31 2012
.SYNOPSIS...
AN UPPER LEVEL RIDGE WILL STRENGTHEN OVER THE AREA THROUGH
SATURDAY... RESULTING IN ABOVE NORMAL TEMPERATURES. THE REMNANTS OF
TROPICAL CYCLONE ISAAC WILL APPROACH THE AREA FROM THE WEST EARLY
NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 1010 PM THURSDAY...
TONIGHT: SURFACE HIGH OFF THE NC COAST WILL YIELD A MOIST SSW RETURN
FLOW OVER CENTRAL NC OVERNIGHT. SKIES HAVE CLEARED ACROSS MOST OF NC
AS OF 02Z. LATEST RUC ANALYSIS SHOWS SURFACE RH OF 95 TO 100 PERCENT
BETWEEN 06 AND 12Z AND SURFACE DEWPOINT DEPRESSIONS OF ONE OR LESS
ACROSS MUCH OF THE AREA BY 09Z...INCREASING SIGNIFICANTLY AFTER 12Z.
THE RUC FORECASTED SURFACE WINDS ARE AROUND 5 KTS AS A SURFACE
TROUGH MOVES ACROSS NORTHERN VA...INCREASING THE PRESSURE GRADIENT
ACROSS THE NORTH EARLY FRIDAY MORNING. IT IS LIKELY THAT FOG WILL
DEVELOP ACROSS MUCH OF THE AREA BETWEEN 09Z AND 12Z...HOWEVER THERE
IS STILL A BIT OF UNCERTAINTY...PARTICULARLY ACROSS THE NORTH WHERE
THE WINDS MAY BE STRONG ENOUGH TO INHIBIT FOG DEVELOPING. HAVE KEPT
AREAS OF FOG IN FOR THE PRE-DAWN HOURS GIVEN THE PERSISTENCE FROM
THURSDAY MORNING...AND THE CLEAR SKIES...LIGHT WINDS AND ABUNDANT
LOW LEVEL MOISTURE. THESE CONDITIONS SHOULD ALSO RESULT IN GOOD
RADIATIONAL COOLING...YIELDING OVERNIGHT LOW TEMPS IN THE MID TO
UPPER 60S. -KC
THERE ARE A COUPLE OF POSSIBLE INHIBITING FACTORS FOR THE
DEVELOPMENT OF DENSE FOG...HOWEVER. ONE IS THE TIGHTENING OF THE
SURFACE PRESSURE GRADIENT AND LEE TROUGH DEVELOPMENT ACROSS NORTHERN
NC...WHICH MAY PRODUCE SOME STIRRING OF SOUTHWESTERLY SURFACE WINDS
OVER THE NORTHERN PIEDMONT AND RESULT IN VERY LOW STRATUS LAYER
AND LIGHTER FOG...VERSUS A HIGHER LIKELIHOOD OF CALM AND DENSE
FOG DEVELOPMENT DIRECTLY WITHIN THE RIDGE AXIS ACROSS SOUTHERN NC.
THE OTHER POSSIBLE INHIBITING FACTOR IS THE POTENTIAL FOR A SCT-BKN
STRATOCUMULUS CLOUD FIELD FROM A RIBBON OF H85 MOISTURE TO ADVECT IN
AN ARC CYCLONICALLY FROM WESTERN TO NORTH CENTRAL TO EASTERN
NC...AFFECTING MAINLY LOCALES NEAR THE VA BORDER IN THE RAH CWFA.
FRI-FRI NIGHT: WARMER AND MAINLY DRY. A LOW LEVEL THERMAL RIDGE ON
THE NORTHERN AND NORTHEASTERN PERIPHERY OF THE AFOREMENTIONED MID
LEVEL RIDGE AND CHARACTERIZED BY TEMPERATURES ALREADY IN THE UPPER
90S TO LOWER 100S OVER NE AND IA AT 18Z...WILL ADVECT EASTWARD TO
THE MIDDLE ATLANTIC STATES AND YIELD PROJECTED LOW LEVEL THICKNESSES
NEAR 1430 METERS AT GSO BY 00Z/1ST. SUCH THICKNESSES SHOULD SUPPORT
TEMPERATURES MAINLY IN THE 89 TO 94 DEGREE RANGE UNDER A MOSTLY
SUNNY SKY. CONVECTIVE POTENTIAL WILL REMAIN QUITE LOW...AND HAS BEEN
LEFT OUT OF THE FORECAST GIVEN THE SUBSIDENT AND CAPPING INFLUENCE
OF THE RIDGE ALOFT...DESPITE SHALLOW LOW LEVEL CONVERGENCE AND BL
MOISTURE GRADIENT INVOF THE PIEDMONT SURFACE TROUGH AXIS. CONTINUED
MAINLY CLEAR...BUT MILDER WITH A SOUTHWESTERLY STIRRING WIND AS THE
SURFACE TROUGH FURTHER STRENGTHENS...WITH LOWS WITHIN A COUPLE OF
DEGREES OF 70.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 235 PM THURSDAY...
FOR SATURDAY/SATURDAY NIGHT: BASED ON THE LATEST MODEL OUTPUT...
THERE IS A RISING RISK FOR LATE AFTERNOON/EVENING STORMS SATURDAY. A
MID LEVEL TROUGH AXIS SWINGING (WITH A SLIGHT POSITIVE TILT) THROUGH
THE NORTHEAST STATES WILL HELP PUSH A BACKDOOR FRONT SOUTHWARD
TOWARD (BUT NOT INTO) NC... WITH LEESIDE TROUGH DEVELOPMENT LIKELY
OVER CENTRAL NC. AS FRIDAY`S MID LEVEL ANTICYCLONE CENTER GETS
SUPPRESSED TO OUR SOUTH... MID LEVEL FLOW WILL STRENGTHEN FROM THE
NORTHWEST. THE RESULTING INCREASE IN DEEP LAYER SHEAR (YET STILL
MODEST AT JUST 15-20 KTS) ACCOMPANIED BY IMPROVING THERMODYNAMICS
(1200-2000 J/KG OF MLCAPE) AND RISING PW TO 1.8-2.0 INCHES WILL
SUPPORT A FEW AFTERNOON SHOWERS AND STORMS... INCLUDING THOSE
EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN AND DROP SOUTHEASTWARD
INTO THE FORECAST AREA LATE IN THE DAY. LOW LEVEL THICKNESSES WILL
BE ABOUT 15-25 METERS ABOVE NORMAL... WHILE 700 MB TEMPS RISE TO
11-12C... COMPARABLE TO UPSTREAM VALUES WHERE SURFACE TEMPS EARLY
THIS AFTERNOON HAD ALREADY EXCEEDED 90. EXPECT HIGHS OF 90-94. WARM
LOWS OF 69-73 WITH MOSTLY CLOUDY SKIES AS CONVECTIVE DEBRIS AND
MID-HIGH CLOUDS STREAMING FROM ISAAC OVERSPREAD THE REGION.
FOR SUNDAY/SUNDAY NIGHT: THIS IS ABOUT THE TIME WE SHOULD BEGIN TO
FEEL THE DIRECT EFFECTS OF THE REMNANTS OF ISAAC. THE CENTER OF THE
REMNANT SURFACE CYCLONE IS EXPECTED TO BE OVER SRN IL SUNDAY
MORNING... DRIFTING INTO INDIANA BEFORE IT BEGINS TO GET ABSORBED
INTO THE SURFACE FRONTAL SYSTEM APPROACHING FROM THE NW. MODELS
SUPPORT HOLDING A WEAK FRONTAL ZONE ORIENTED ROUGHLY FROM KY ACROSS
SW NC AND ALONG THE NC/SC BORDER... AND THIS MAY REMAIN A FOCUS FOR
SCATTERED STORMS DEVELOPING WITH DAYTIME HEATING AND DESTABILIZATION
(MLCAPE OF 1500-2400 J/KG)... AND WITH DEEP LAYER SHEAR INCHING UP A
BIT TO 20-25 KTS. PW VALUES WILL STAY QUITE HIGH... CLOSE TO 2.0
INCHES... SO IT SHOULD NOT TAKE MUCH TO INDUCE CONVECTION. HAVE
BUMPED UP POPS TO A 40-50 PERCENT CHANCE... MAINLY AFTERNOON THROUGH
EVENING. HIGHS 85-89 WITH GENERALLY MOSTLY CLOUDY SKIES. LOWS 68-72
WITH LOWER RAIN CHANCES OVERNIGHT. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 115 PM THURSDAY...
FOR MONDAY/MONDAY NIGHT: MODELS AGREE ON ISAAC`S CORRESPONDING MID
LEVEL SHORTWAVE TROUGH SLOWLY PASSING OVER KY/TN AS IT APPROACHES NC
FROM THE WEST... ALTHOUGH MODEL SOLUTIONS VARY WITH RESPECT TO ITS
SPEED AND AMPLITUDE. WITH A STRONG MID LEVEL RIDGE COVERING THE
DESERT SOUTHWEST AND A FAST FLOW OVER THE NORTHERN PORTION OF THE
CONUS... THIS WAVE SHOULD SLOWLY DEAMPLIFY AS POLAR SHORTWAVE ENERGY
DROPS ESE THROUGH ONTARIO... BUT IT SHOULD REMAIN A DISTINCT AND
TRACKABLE WAVE AS IT MOVES INTO THE SRN APPALACHIANS. THE GFS/ECMWF
BOTH DEPICT WEAK NW-SE WARM FRONTOGENESIS OVER THE CAROLINAS AS THE
WAVE APPROACHES... AND BOTH ALSO DEVELOP WIDESPREAD CONVECTION
MONDAY AFTERNOON ACCOMPANYING THE MID LEVEL HEIGHT FALLS WITH
CONFLUENT GULF- AND ATLANTIC-SOURCE SOUTHEAST AND SOUTHERLY LOW
LEVEL FLOW. GIVEN THE IMPROVING DYNAMICS AND INSTABILITY... WILL
HAVE GOOD CHANCES OF SHOWERS AND A FEW STORMS MONDAY AFTERNOON AND
EVENING... DECREASING WITH LOSS OF HEATING OVERNIGHT. THICKNESSES
POINT TO HIGHS IN THE MID 80S. IT`S WORTH NOTING THAT IF THE LOW
LEVEL WARM FRONT SETS UP TO OUR SOUTH WITH NUMEROUS SHOWERS OVER
CENTRAL NC WITHIN THE BIT MORE STABLE AIR... WE COULD SEE COOLER
TEMPS THAN ARE CURRENTLY ANTICIPATED.
FOR TUESDAY THROUGH THURSDAY: A MARKED DIVERGENCE IN MODEL SOLUTIONS
BECOMES PROBLEMATIC FOR OUR DAY-TO-DAY FORECAST STARTING TUESDAY.
ACCORDING TO THE 00Z/06Z GFS... THE WEAKENING MID LEVEL TROUGH IS
EXPECTED TO HAVE SHIFTED SE OF THE CWA BY WEDNESDAY MORNING AS THE
MEAN LONGWAVE TROUGH DIGS FROM JAMES BAY THROUGH THE ERN GREAT LAKES
TO THE MIDATLANTIC COAST... AND AS A SURFACE COLD FRONT PUSHES SE
THROUGH CENTRAL NC. BUT THERE ARE INDICATIONS THAT THE 00Z/06Z GFS
MAY BE TOO AGGRESSIVE WITH ITS NORTHEAST-NOAM HEIGHT FALLS... AS THE
00Z ECMWF FAVORS DIGGING A TROUGH MUCH MORE WESTWARD INTO MT/ID BY
LATE TUESDAY NIGHT. THE ECMWF (WHICH IS THE STRONGEST WITH ISAAC`S
REMNANT MID LEVEL SHORTWAVE TROUGH) ALSO DEVELOPS A CLOSED LOW WELL
OFF THE BAHAMAS ON SUNDAY AND THEN BRINGS THIS LOW WESTWARD AND
NORTHWESTWARD TOWARD THE SOUTHEAST COAST BY LATE TUESDAY. IN TERMS
OF SENSIBLE WEATHER... THIS RESULTS IN STORMY-EARLY-BUT-CLEARING
WEATHER DURING THIS PERIOD ON THE GFS... AND MILD AND QUITE
WET/STORMY (ALMOST TROPICAL-LIKE) ON THE ECMWF. THE ECMWF ENSEMBLE
MEAN PROVIDES A MIDDLE-OF-THE-ROAD SOLUTION... GRADUALLY DEEPENING
THE LONGWAVE TROUGH OVER THE UPPER MIDWEST AND WRN GREAT LAKES... A
LITTLE WEST OF THE 00Z/06Z GFS BUT CLOSER IN LINE WITH THE NEW 12Z
GFS. FAVORING THIS... EXPECT A GOOD CHANCE OF SHOWERS/STORMS THROUGH
TUESDAY... DECREASING WEST BUT REMAINING FAIRLY HIGH IN THE EASTERN
FORECAST AREA ON WEDNESDAY... AND A LOWER CHANCE ON THURSDAY AS THE
SURFACE FRONT SHOULD BE EAST OF THE AREA WITH DRIER AIR FILTERING IN
FROM THE NW. BUT CONFIDENCE IN THE DETAILS HERE IS RATHER LOW... AND
THIS SCENARIO COULD CHANGE IN THE COMING DAYS AS THE FORECAST IS
REFINED. LOW LEVEL THICKNESSES ARE UNLIKELY TO REACH HIGHLY
ANOMALOUS VALUES... AS THEY SHOULD HOLD WITHIN 5-15 METERS ABOVE
NORMAL. EXPECT HIGHS MOSTLY IN THE MID 80S WITH LOWS IN THE MID 60S
TO NEAR 70. -GIH
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 140 AM FRIDAY...
24-HR TAF PERIOD:
A CONTINUED MOIST BOUNDARY LAYER COUPLED WITH LIGHT AND VARIABLE TO
CALM WINDS AND CURRENT CLEAR SKIES WILL LEAD TO ANOTHER MORNING OF
LOW STRATUS AND FOG ACROSS CENTRAL NC. EXPECT THE WORST CONDITIONS
TO BE ACROSS SOUTHERN AND POSSIBLY EASTERN PORTIONS OF THE AREA...
WHERE IFR/LIFR CONDITIONS WILL BE POSSIBLE (KRWI/KFAY). FURTHER
NORTH AND WEST... A DEVELOPING SURFACE TROUGH MAY PREVENT WINDS FROM
GOING CALM. THIS WOULD LOWER THE PROBABILITY OF DENSE FOG... AND
POSSIBLE FAVOR MORE STRATUS (ESPECIALLY AT KGSO/KINT). THUS... WILL
CONTINUE TO GO WITH A COMBINATION OF STRATUS AN FOG AT THESE SITES
(KGSO/KINT/KRDU)... WITH GENERALLY MVFR/IFR CONDITIONS DEVELOPING
THIS MORNING IN THE PRE-DAWN HOURS. EXPECT AND LOW STRATUS AND OR
FOG TO LIFT/DISSIPATE BY 15/16Z AT THE LATEST. VFR CONDITIONS ARE
EXPECTED AFTER THE FOG AND STRATUS LIFT ALONG WITH CONTINUED DRY
WEATHER... AS STRONG HIGH PRESSURE ALOFT BUILDS OVER THE AREA.
LOOKING AHEAD:
VFR CONDITIONS ARE EXPECTED TO RULE THROUGH SAT NIGHT IN ASSOCIATION
WITH THE AFOREMENTIONED UPPER LEVEL RIDGE...THOUGH A SMALL CHANCE
FOR SHOWERS/STORMS CANNOT BE RULED OUT SAT AFTERNOON/EVENING... BEST
CHANCE AT KGSO/KINT. THE NEXT CHANCE FOR ADVERSE AVIATION CONDITIONS
WILL BE LATE SUNDAY INTO MON/TUE AS THE REMNANTS OF TROPICAL CYCLONE
ISAAC PROGRESS EAST TOWARD THE REGION.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BSD/JB
NEAR TERM...KC/MWS/SEC
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...BSD/VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1013 PM EDT THU AUG 30 2012
.SYNOPSIS...
AN UPPER LEVEL RIDGE WILL STRENGTHEN OVER THE CAROLINAS THROUGH
SATURDAY...RESULTING IN ABOVE NORMAL TEMPERATURES. THE REMNANTS OF
TROPICAL CYCLONE ISAAC WILL APPROACH THE AREA FROM THE WEST EARLY
NEXT WEEK.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 1010 PM THURSDAY...
TONIGHT: SURFACE HIGH OFF THE NC COAST WILL YIELD A MOIST SSW RETURN
FLOW OVER CENTRAL NC OVERNIGHT. SKIES HAVE CLEARED ACROSS MOST OF NC
AS OF 02Z. LATEST RUC ANALYSIS SHOWS SURFACE RH OF 95 TO 100 PERCENT
BETWEEN 06 AND 12Z AND SURFACE DEWPOINT DEPRESSIONS OF ONE OR LESS
ACROSS MUCH OF THE AREA BY 09Z...INCREASING SIGNIFICANTLY AFTER 12Z.
THE RUC FORECASTED SURFACE WINDS ARE AROUND 5 KTS AS A SURFACE
TROUGH MOVES ACROSS NORTHERN VA...INCREASING THE PRESSURE GRADIENT
ACROSS THE NORTH EARLY FRIDAY MORNING. IT IS LIKELY THAT FOG WILL
DEVELOP ACROSS MUCH OF THE AREA BETWEEN 09Z AND 12Z...HOWEVER THERE
IS STILL A BIT OF UNCERTAINTY...PARTICULARLY ACROSS THE NORTH WHERE
THE WINDS MAY BE STRONG ENOUGH TO INHIBIT FOG DEVELOPING. HAVE KEPT
AREAS OF FOG IN FOR THE PRE-DAWN HOURS GIVEN THE PERSISTENCE FROM
THURSDAY MORNING...AND THE CLEAR SKIES...LIGHT WINDS AND ABUNDANT
LOW LEVEL MOISTURE. THESE CONDITIONS SHOULD ALSO RESULT IN GOOD
RADIATIONAL COOLING...YIELDING OVERNIGHT LOW TEMPS IN THE MID TO
UPPER 60S. -KC
THERE ARE A COUPLE OF POSSIBLE INHIBITING FACTORS FOR THE
DEVELOPMENT OF DENSE FOG...HOWEVER. ONE IS THE TIGHTENING OF THE
SURFACE PRESSURE GRADIENT AND LEE TROUGH DEVELOPMENT ACROSS NORTHERN
NC...WHICH MAY PRODUCE SOME STIRRING OF SOUTHWESTERLY SURFACE WINDS
OVER THE NORTHERN PIEDMONT AND RESULT IN VERY LOW STRATUS LAYER
AND LIGHTER FOG...VERSUS A HIGHER LIKELIHOOD OF CALM AND DENSE
FOG DEVELOPMENT DIRECTLY WITHIN THE RIDGE AXIS ACROSS SOUTHERN NC.
THE OTHER POSSIBLE INHIBITING FACTOR IS THE POTENTIAL FOR A SCT-BKN
STRATOCUMULUS CLOUD FIELD FROM A RIBBON OF H85 MOISTURE TO ADVECT IN
AN ARC CYCLONICALLY FROM WESTERN TO NORTH CENTRAL TO EASTERN
NC...AFFECTING MAINLY LOCALES NEAR THE VA BORDER IN THE RAH CWFA.
FRI-FRI NIGHT: WARMER AND MAINLY DRY. A LOW LEVEL THERMAL RIDGE ON
THE NORTHERN AND NORTHEASTERN PERIPHERY OF THE AFOREMENTIONED MID
LEVEL RIDGE AND CHARACTERIZED BY TEMPERATURES ALREADY IN THE UPPER
90S TO LOWER 100S OVER NE AND IA AT 18Z...WILL ADVECT EASTWARD TO
THE MIDDLE ATLANTIC STATES AND YIELD PROJECTED LOW LEVEL THICKNESSES
NEAR 1430 METERS AT GSO BY 00Z/1ST. SUCH THICKNESSES SHOULD SUPPORT
TEMPERATURES MAINLY IN THE 89 TO 94 DEGREE RANGE UNDER A MOSTLY
SUNNY SKY. CONVECTIVE POTENTIAL WILL REMAIN QUITE LOW...AND HAS BEEN
LEFT OUT OF THE FORECAST GIVEN THE SUBSIDENT AND CAPPING INFLUENCE
OF THE RIDGE ALOFT...DESPITE SHALLOW LOW LEVEL CONVERGENCE AND BL
MOISTURE GRADIENT INVOF THE PIEDMONT SURFACE TROUGH AXIS. CONTINUED
MAINLY CLEAR...BUT MILDER WITH A SOUTHWESTERLY STIRRING WIND AS THE
SURFACE TROUGH FURTHER STRENGTHENS...WITH LOWS WITHIN A COUPLE OF
DEGREES OF 70.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 235 PM THURSDAY...
FOR SATURDAY/SATURDAY NIGHT: BASED ON THE LATEST MODEL OUTPUT...
THERE IS A RISING RISK FOR LATE AFTERNOON/EVENING STORMS SATURDAY. A
MID LEVEL TROUGH AXIS SWINGING (WITH A SLIGHT POSITIVE TILT) THROUGH
THE NORTHEAST STATES WILL HELP PUSH A BACKDOOR FRONT SOUTHWARD
TOWARD (BUT NOT INTO) NC... WITH LEESIDE TROUGH DEVELOPMENT LIKELY
OVER CENTRAL NC. AS FRIDAY`S MID LEVEL ANTICYCLONE CENTER GETS
SUPPRESSED TO OUR SOUTH... MID LEVEL FLOW WILL STRENGTHEN FROM THE
NORTHWEST. THE RESULTING INCREASE IN DEEP LAYER SHEAR (YET STILL
MODEST AT JUST 15-20 KTS) ACCOMPANIED BY IMPROVING THERMODYNAMICS
(1200-2000 J/KG OF MLCAPE) AND RISING PW TO 1.8-2.0 INCHES WILL
SUPPORT A FEW AFTERNOON SHOWERS AND STORMS... INCLUDING THOSE
EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN AND DROP SOUTHEASTWARD
INTO THE FORECAST AREA LATE IN THE DAY. LOW LEVEL THICKNESSES WILL
BE ABOUT 15-25 METERS ABOVE NORMAL... WHILE 700 MB TEMPS RISE TO
11-12C... COMPARABLE TO UPSTREAM VALUES WHERE SURFACE TEMPS EARLY
THIS AFTERNOON HAD ALREADY EXCEEDED 90. EXPECT HIGHS OF 90-94. WARM
LOWS OF 69-73 WITH MOSTLY CLOUDY SKIES AS CONVECTIVE DEBRIS AND
MID-HIGH CLOUDS STREAMING FROM ISAAC OVERSPREAD THE REGION.
FOR SUNDAY/SUNDAY NIGHT: THIS IS ABOUT THE TIME WE SHOULD BEGIN TO
FEEL THE DIRECT EFFECTS OF THE REMNANTS OF ISAAC. THE CENTER OF THE
REMNANT SURFACE CYCLONE IS EXPECTED TO BE OVER SRN IL SUNDAY
MORNING... DRIFTING INTO INDIANA BEFORE IT BEGINS TO GET ABSORBED
INTO THE SURFACE FRONTAL SYSTEM APPROACHING FROM THE NW. MODELS
SUPPORT HOLDING A WEAK FRONTAL ZONE ORIENTED ROUGHLY FROM KY ACROSS
SW NC AND ALONG THE NC/SC BORDER... AND THIS MAY REMAIN A FOCUS FOR
SCATTERED STORMS DEVELOPING WITH DAYTIME HEATING AND DESTABILIZATION
(MLCAPE OF 1500-2400 J/KG)... AND WITH DEEP LAYER SHEAR INCHING UP A
BIT TO 20-25 KTS. PW VALUES WILL STAY QUITE HIGH... CLOSE TO 2.0
INCHES... SO IT SHOULD NOT TAKE MUCH TO INDUCE CONVECTION. HAVE
BUMPED UP POPS TO A 40-50 PERCENT CHANCE... MAINLY AFTERNOON THROUGH
EVENING. HIGHS 85-89 WITH GENERALLY MOSTLY CLOUDY SKIES. LOWS 68-72
WITH LOWER RAIN CHANCES OVERNIGHT. -GIH
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 115 PM THURSDAY...
FOR MONDAY/MONDAY NIGHT: MODELS AGREE ON ISAAC`S CORRESPONDING MID
LEVEL SHORTWAVE TROUGH SLOWLY PASSING OVER KY/TN AS IT APPROACHES NC
FROM THE WEST... ALTHOUGH MODEL SOLUTIONS VARY WITH RESPECT TO ITS
SPEED AND AMPLITUDE. WITH A STRONG MID LEVEL RIDGE COVERING THE
DESERT SOUTHWEST AND A FAST FLOW OVER THE NORTHERN PORTION OF THE
CONUS... THIS WAVE SHOULD SLOWLY DEAMPLIFY AS POLAR SHORTWAVE ENERGY
DROPS ESE THROUGH ONTARIO... BUT IT SHOULD REMAIN A DISTINCT AND
TRACKABLE WAVE AS IT MOVES INTO THE SRN APPALACHIANS. THE GFS/ECMWF
BOTH DEPICT WEAK NW-SE WARM FRONTOGENESIS OVER THE CAROLINAS AS THE
WAVE APPROACHES... AND BOTH ALSO DEVELOP WIDESPREAD CONVECTION
MONDAY AFTERNOON ACCOMPANYING THE MID LEVEL HEIGHT FALLS WITH
CONFLUENT GULF- AND ATLANTIC-SOURCE SOUTHEAST AND SOUTHERLY LOW
LEVEL FLOW. GIVEN THE IMPROVING DYNAMICS AND INSTABILITY... WILL
HAVE GOOD CHANCES OF SHOWERS AND A FEW STORMS MONDAY AFTERNOON AND
EVENING... DECREASING WITH LOSS OF HEATING OVERNIGHT. THICKNESSES
POINT TO HIGHS IN THE MID 80S. IT`S WORTH NOTING THAT IF THE LOW
LEVEL WARM FRONT SETS UP TO OUR SOUTH WITH NUMEROUS SHOWERS OVER
CENTRAL NC WITHIN THE BIT MORE STABLE AIR... WE COULD SEE COOLER
TEMPS THAN ARE CURRENTLY ANTICIPATED.
FOR TUESDAY THROUGH THURSDAY: A MARKED DIVERGENCE IN MODEL SOLUTIONS
BECOMES PROBLEMATIC FOR OUR DAY-TO-DAY FORECAST STARTING TUESDAY.
ACCORDING TO THE 00Z/06Z GFS... THE WEAKENING MID LEVEL TROUGH IS
EXPECTED TO HAVE SHIFTED SE OF THE CWA BY WEDNESDAY MORNING AS THE
MEAN LONGWAVE TROUGH DIGS FROM JAMES BAY THROUGH THE ERN GREAT LAKES
TO THE MIDATLANTIC COAST... AND AS A SURFACE COLD FRONT PUSHES SE
THROUGH CENTRAL NC. BUT THERE ARE INDICATIONS THAT THE 00Z/06Z GFS
MAY BE TOO AGGRESSIVE WITH ITS NORTHEAST-NOAM HEIGHT FALLS... AS THE
00Z ECMWF FAVORS DIGGING A TROUGH MUCH MORE WESTWARD INTO MT/ID BY
LATE TUESDAY NIGHT. THE ECMWF (WHICH IS THE STRONGEST WITH ISAAC`S
REMNANT MID LEVEL SHORTWAVE TROUGH) ALSO DEVELOPS A CLOSED LOW WELL
OFF THE BAHAMAS ON SUNDAY AND THEN BRINGS THIS LOW WESTWARD AND
NORTHWESTWARD TOWARD THE SOUTHEAST COAST BY LATE TUESDAY. IN TERMS
OF SENSIBLE WEATHER... THIS RESULTS IN STORMY-EARLY-BUT-CLEARING
WEATHER DURING THIS PERIOD ON THE GFS... AND MILD AND QUITE
WET/STORMY (ALMOST TROPICAL-LIKE) ON THE ECMWF. THE ECMWF ENSEMBLE
MEAN PROVIDES A MIDDLE-OF-THE-ROAD SOLUTION... GRADUALLY DEEPENING
THE LONGWAVE TROUGH OVER THE UPPER MIDWEST AND WRN GREAT LAKES... A
LITTLE WEST OF THE 00Z/06Z GFS BUT CLOSER IN LINE WITH THE NEW 12Z
GFS. FAVORING THIS... EXPECT A GOOD CHANCE OF SHOWERS/STORMS THROUGH
TUESDAY... DECREASING WEST BUT REMAINING FAIRLY HIGH IN THE EASTERN
FORECAST AREA ON WEDNESDAY... AND A LOWER CHANCE ON THURSDAY AS THE
SURFACE FRONT SHOULD BE EAST OF THE AREA WITH DRIER AIR FILTERING IN
FROM THE NW. BUT CONFIDENCE IN THE DETAILS HERE IS RATHER LOW... AND
THIS SCENARIO COULD CHANGE IN THE COMING DAYS AS THE FORECAST IS
REFINED. LOW LEVEL THICKNESSES ARE UNLIKELY TO REACH HIGHLY
ANOMALOUS VALUES... AS THEY SHOULD HOLD WITHIN 5-15 METERS ABOVE
NORMAL. EXPECT HIGHS MOSTLY IN THE MID 80S WITH LOWS IN THE MID 60S
TO NEAR 70. -GIH
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 900 PM THURSDAY...
24-HR TAF PERIOD:
VFR CONDITIONS THIS EVENING ARE EXPECTED TO DETERIORATE OVERNIGHT IN
ASSOCIATION WITH WIDESPREAD FOG GIVEN CLEAR SKIES...CALM OR LIGHT
WINDS...AND A MOIST BOUNDARY LAYER. THE PRESSURE GRADIENT IS
EXPECTED TO TIGHTEN BETWEEN 06-12Z IN ASSOC/W A DEVELOPING LEE
TROUGH...AND THIS MAY HELP TO MITIGATE THE POTENTIAL FOR DENSE FOG
AT THE NORTHERN (INT/GSO/RDU) TAF SITES...THOUGH UNCERTAINTY
PERSISTS...AND IT IS POSSIBLE THAT IFR/LIFR STRATUS MAY DEVELOP AT
THE INT/GSO TERMINALS WHERE DEEPER MOISTURE IS PRESENT. FURTHER
SOUTH...THE FAY/RWI TAF SITES ARE MOST LIKELY TO SEE DENSE FOG AND
LIFR CONDITIONS...SIMILAR TO THIS MORNING...BETWEEN 07-12Z. FOG WILL
LIFT/SCATTER OUT TO VFR BETWEEN 12-14Z GIVEN SUNNY SKIES AND STRONG
INSOLATION AS AN UPPER LEVEL RIDGE STRENGTHENS OVER THE REGION.
DRY/VFR CONDITIONS WILL RULE THE REMAINDER OF THE TAF PERIOD.
LOOKING AHEAD:
VFR CONDITIONS ARE EXPECTED TO RULE THROUGH SAT NIGHT IN ASSOCIATION
WITH THE AFOREMENTIONED UPPER LEVEL RIDGE...THOUGH A SMALL CHANCE
FOR SHOWERS/STORMS CANNOT BE RULED OUT SAT EVENING. THE NEXT CHANCE
FOR ADVERSE AVIATION CONDITIONS WILL BE LATE SUNDAY INTO MON/TUE AS
THE REMNANTS OF TROPICAL CYCLONE ISAAC PROGRESS EAST TOWARD THE
REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JB
NEAR TERM...KC/MWS/SEC
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
929 AM EDT THU AUG 30 2012
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE NORTH TODAY AND EXTEND OVER THE
AREA THROUGH SATURDAY. A COLD FRONT WILL APPROACH FROM THE NORTH
SATURDAY NIGHT AND STALL OVER NORTHERN SECTIONS SUNDAY AND MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 930 AM THURSDAY...MUCH DIFFERENT AIRMASS THIS MORNING AS
OPPOSED TO RECENT DAYS AS PRECIPITABLE WATER HAS DROPPED FROM 2.4
INCHES YESTERDAY TO 1.4 INCHES TODAY. LATEST RAP MODEL KEEPS
PRECIPITATION TO THE SOUTH OF OUR CWA WHICH IS IN AGREEMENT WITH
CURRENT FORECAST AND NO CHANGES MADE TO POPS. NAM DOES INDICATE
SOME WEAK 500 MB VORTICITY SWINGING ACROSS THE REGION AND CANNOT
RULE OUT AN ISOLATED SHOWER OR TWO...BUT COVERAGE WILL BE LIMITED
AND POPS CAN BE LEFT OUT OF THE FORECAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
AS OF 330 AM THURSDAY...RIDGING SFC AND ALOFT WILL PRODUCE FAIR
CONDITIONS TONIGHT. MIN TEMPS RANGING FROM MID-UPR 60S INLAND TO
LOW-MID 70S COAST.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 250 AM THU...WILL CONTINUE DRY WEATHER FORECAST FRIDAY AND
SATURDAY AS STRONG RIDGE BRIEFLY BUILDS OVER THE EASTERN US. SOME
OF THE MODELS CONTINUE TO INDICATE ISOLATED CONVECTION SATURDAY
BUT WITH LACK OF UPPER SUPPORT WILL MAINTAIN DRY FORECAST. A WEAK
COLD FRONT WILL ATTEMPT TO DRIFT SOUTH INTO NORTHERN CWA LATE
SATURDAY AND SATURDAY NIGHT THEN SHOULD DRIFT BACK NORTH INTO VA
SUNDAY. SUNDAY INTO MONDAY THE REMNANTS OF ISSAC ALOFT WILL MOVE
INTO THE LOWER LAKES AND BECOME ABSORBED INTO A UPPER TROUGH
MOVING ACROSS SOUTHERN CANADA. RESULTING NW FLOW ALOFT OVER THE
EASTERN US WILL ALLOW ANOTHER COLD FRONT TO SLOWLY SLIDE SOUTHEAST
ACROSS THE REGION. THE MODELS DIFFER ON TIMING OF THIS FEATURE BUT
THEY ALL TEND TO AGREE THAT MOISTURE AND LIFT WILL BE INCREASING
ACROSS EASTERN NC SO WILL CONTINUE CHANCE POPS MONDAY THROUGH
WEDNESDAY. EXPECT TEMPS NEAR OR SLIGHTLY ABOVE CLIMO THROUGH THE
PERIOD...WITH HIGHS 85-90 DEG AND LOWS IN THE 70S.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
SHORT TERM /THROUGH 12Z FRIDAY/...
AS OF 700 AM THURSDAY...CURRENT VSBYS AROUND 2SM AT KPGV..KOAJ AND
KISO WILL IMPROVE TO FR BY 13Z. VFR PREVAILING ALL SITES REST OF DAY
INTO EVENING WITH NO CONVECTIVE ACTIVITY EXPECTED. MOS GDNC
INDICATING PERIOD OF IFR VSBYS AGAIN 09Z-12Z LATE TONIGHT...AND
CONDITIONS MAY BE MORE CONDUCIVE WITH MOSTLY CLEAR SKIES.
HOWEVER...GDNC HAS BEEN OVERDONE WITH DURATION OF IFR VSBYS PAST FEW
DAYS AND WILL GO WITH PREVAILING MVFR 3SM FOR NOW.
LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 250 AM THU...PREDOMINATE VFR CONDITIONS EXPECTED THROUGH THE
WEEKEND...OUTSIDE OF ANY BRIEF MORNING FOG. MOISTURE WILL BEGIN TO
INCREASE ACROSS THE AREA SUNDAY INTO MONDAY WITH PRECIP CHANCES
INCREASING. SUB-VFR CONDITIONS WILL BE POSSIBLE SUN INTO MON AHEAD
OF A SLOW MOVING COLD FRONT.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 700 AM THURSDAY...GENERALLY E/SE WINDS AT 10 KNOTS OR LESS
ACROSS THE COASTAL WATERS EXCEPT WINDS GUSTING CLOSE TO 15 KNOTS
FROM CAPE LOOKOUT SOUTHWARD. SEAS ARE 2 TO 4 FEET WITH A 9 TO 11
SECOND SWELL COMPONENT. WINDS SHOULD BECOME MORE SOUTHERLY TODAY
AND THEN BECOME S-SW OVERNIGHT WITH SPEEDS INCREASING TO 10-15 KT
NORTHERN WATERS WITH TIGHTENING PRES GRAD. WW3 AND SWAN IN
AGREEMENT ON SEAS REMAINING 2-3 FT DURING PERIOD.
LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 250 AM THU...TYPICAL SUMMERTIME PATTERN RETURNS FRI WITH HIGH
PRESSURE OVER THE AREA RESULTING IN SW WINDS AOB 15KT AND SEAS
2-3FT. MODELS IN GOOD AGREEMENT SHOWING SW SURGE FRIDAY
EVENING...GENERALLY 10-20KT...AS PGRADIENT TIGHTENS BTWN HIGH
PRESSURE OVER THE AREA AND LOW PRESSURE NEAR CANADA/NEWFOUNDLAND.
A WEAK FRONTAL BOUNDARY WILL APPROACH THE NORTHERN WATERS AND
ALBEMARLE SOUND LATE SATURDAY INTO SUNDAY...WITH FLOW LIKELY
BECOMING MORE ELY SUN NORTH OF HATTERAS...STILL EXPECT SPEEDS
BELOW 15KT. SUN INTO MON EXPECT S/SE FLOW. OVERALL SEAS WILL
REMAIN 2-4FT THROUGH THE PERIOD.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC
NEAR TERM...JBM/CTC
SHORT TERM...CTC
LONG TERM...JME/CQD
AVIATION...JBM/CQD
MARINE...JBM/CTC/CQD/LEP
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1037 PM EDT WED AUG 29 2012
.SYNOPSIS...
A COLD FRONT WILL DROP INTO THE AREA TONIGHT. A GRADUAL DRYING AND
WARMING TREND WILL BEGIN THURSDAY AND CONTINUE INTO THE WEEKEND AS
HIGH PRESSURE BUILDS INTO THE AREA. A COLD FRONT WILL APPROACH FROM
THE NORTH AND WEST EARLY NEXT WEEK BUT WILL REMAIN NORTH OF THE AREA
THROUGH MID WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM WEDNESDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO
ANY OF MY EARLIER THINKING. THE LATEST SEVERAL HRRR MODEL RUNS
REMAIN INSISTENT THE CONVECTION ACROSS SOUTHEASTERN SOUTH CAROLINA
WILL SPREAD INTO MUCH OF OUR EASTERN SOUTH CAROLINA COUNTIES AFTER
MIDNIGHT...ALBEIT IN A WEAKENED STATE. THE 12Z MHX SOUNDING SHOWS
300 MB WIND SPEEDS HAVE INCREASED TO 55 KNOTS WHICH IS IN GOOD
AGREEMENT WITH 18Z MODEL PROGS...AND CONFIRMS THE IDEA THAT UPPER
LEVEL DYNAMICS WILL HELP SUSTAIN LATE NIGHT SHOWERS. PREVIOUS
DISCUSSION FROM 730 PM FOLLOWS...
A SURFACE COLD FRONT EXTENDS EAST TO WEST ACROSS SOUTH-CENTRAL NORTH
CAROLINA APPROXIMATELY FROM NEW BERN THROUGH FAYETTEVILLE TO JUST
NORTH OF CHARLOTTE. THIS BOUNDARY SEPARATES TROPICAL AIR TO THE
SOUTH (MID 70S DEWPOINTS) FROM SOMEWHAT DRIER CONTINENTAL AIR (60S
DEWPOINTS) TO THE NORTH. SURFACE TO 850 MB WINDS ARE VERY WEAK ON
EITHER SIDE OF THE FRONT SO THERE IS NO LOW-LEVEL CONVERGENCE TO
SPEAK OF. THE FRONT SHOULD DROP SOUTH OVERNIGHT AND WILL END UP IN
THE MYRTLE BEACH/GEORGETOWN AREA LATE. THERE IS LITTLE PUSH OF WIND
ON EITHER SIDE OF THE FRONT AND WE ARE ACTUALLY ANTICIPATING NEARLY
CALM CONDITIONS OVERNIGHT.
SEVERAL CLUSTERS OF SHOWERS AND THUNDERSTORMS HAVE PRODUCED HEAVY
RAIN AND FLOODING LATE THIS AFTERNOON MAINLY ACROSS EASTERN SOUTH
CAROLINA. THESE STORMS WERE DRIVEN BY PURE INSTABILITY WITH CAPE
VALUES EARLIER NEAR 2000 J/KG BUT WITH NO MENTIONABLE SHEAR OR UPPER
DISTURBANCES. MUCH OF THE EARLIER INSTABILITY HAS ALREADY BEEN
DISSIPATED BY THE STORMS AND THE BOUNDARY LAYER IS BECOMING CAPPED
TO SURFACE-BASED CONVECTION. ONCE THE CURRENT CONVECTIVE ACTIVITY
MOVES OFF THE SOUTH CAROLINA COAST WE SHOULD HAVE A FEW HOURS OF
GENERALLY DRY CONDITIONS LATE THIS EVENING.
MODELS SHOW A RESURGENCE OF SHOWER ACTIVITY ACROSS EASTERN SOUTH
CAROLINA AFTER MIDNIGHT AS SYNOPTIC LIFT INCREASES WITH A 300 MB JET
STREAK DEVELOPING ACROSS EASTERN NORTH CAROLINA. THE RIGHT-ENTRANCE
REGION OF THIS JET SHOULD PRODUCE ENOUGH LIFT FOR ELEVATED
CONVECTION...MAINLY FROM MIDNIGHT THROUGH ABOUT 5-6 AM THURSDAY.
SHOWER CHANCES ARE LESS ACROSS SOUTHEASTERN NORTH CAROLINA WITH A
LESS FAVORABLE POSITIONING OF THE JET...BUT WE`RE STILL PAINTING
20-40 PERCENT CHANCES OF SHOWERS AFTER MIDNIGHT HERE.
LOWS SHOULD FALL INTO THE LOWER 70S INLAND WITH MID 70S AT THE
COAST...VERY SIMILAR TO LAST NIGHT.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...THURSDAY WILL BE A DAY OF TRANSITION AS A
SLOWLY MOVING COLD FRONT CONTINUES TO DRIFT SOUTH ACROSS THE CWA.
ALTHOUGH TEMPS WILL NOT CHANGE MUCH WITH THIS BOUNDARY...DRIER AIR
BUILDS IN BEHIND IT AND PRECIP CHANCES WILL FALL SLOWLY THROUGH THE
DAY. BY THE END OF THE DAY...CONVECTIVE CHANCES SHOULD DECREASE
SIGNIFICANTLY.
FOR THE REMAINDER OF THE PERIOD...DRY WEATHER IS EXPECTED UNDER
CLEAR TO PARTLY CLOUDY SKIES. DAYTIME HIGHS WILL GENERALLY REACH
THE MIDDLE 80S THURSDAY AND MID 80S TO AROUND 90 FRIDAY. LOWS EACH
NIGHT SHOULD FALL TO THE UPPER 60S TO LOWER 70S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 PM WEDNESDAY...RIDGE SFC-ALOFT OVERHEAD ON SATURDAY WILL BE
SHUNTED SOUTH AS THE REMNANTS OF ISAAC MAKE THEIR WAY FROM THE MID
MISSISSIPPI RIVER VALLEY INTO THE MID-ATLANTIC REGION. SOUTHERLY
LOW-LEVEL FLOW WILL DEVELOP BY LATE SATURDAY AND PERSIST THROUGH THE
PERIOD. THIS WILL RESULT IN A WARM...MOIST AND UNSTABLE AIRMASS
ACROSS THE AREA...FAVORABLE FOR SCATTERED CONVECTION. PRECIPITABLE
WATERS WILL SURGE TO 2.25 INCHES BY SUNDAY AND REMAIN IN EXCESS OF
TWO INCHES THROUGH TUESDAY. THEREFORE LOCALLY HEAVY DOWNPOURS WOULD
BE EXPECTED IN ASSOCIATION WITH THE SHOWERS/TSTMS. MID-LEVEL TROUGH
AXIS WILL MOVE OFFSHORE WEDNESDAY AND DRYING IN THE H7-H3 LAYER
SHOULD RESULT IN LESSER COVERAGE OF CONVECTION.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 00Z...VFR THROUGH THE VALID PERIOD...WITH EXCEPTION OF
MVFR/IFR OVERNIGHT INTO THE MORNING HOURS.
CURRENT RADAR DEPICTS SCATTERED HEAVY SHOWERS ALONG THE
COAST...CREATING BRIEF MVFR TO KCRE/KMYR. AFTER THIS ACTIVITY MOVES
OFFSHORE...THINGS WILL BE QUIET FOR A FEW HOURS BEFORE ANOTHER ROUND
OF ISOLATED/SCATTERED SHRA IS POSSIBLE OVERNIGHT. WITH NEARLY CALM
WINDS AND ABUNDANT MOISTURE ACROSS THE AREA...ANTICIPATE
FOG DEVELOPMENT LATE OVERNIGHT INTO THE EARLY MORNING HOURS TO
CREATE MVFR/IFR RESTRICTIONS DUE TO VISIBILITIES...AND POSSIBLY
CIGS...ESPECIALLY INLAND. HOWEVER...OVERALL AFFECT OF FOG
DEVELOPMENT WILL DEPEND ON OPACITY OF LINGERING CLOUD DEBRIS. AFTER
DAYBREAK...FOG WILL DISSIPATE GIVING WAY TO VFR CONDITIONS ACROSS
THE AREA. EAST WINDS WILL PREVAIL...SUSTAINED AOB 10 KTS...GRADUALLY
SHIFTING TO THE SE AT THE COAST.
EXTENDED OUTLOOK...VFR THROUGH SATURDAY. A CHANCE FOR SCATTERED
CONVECTION SUNDAY AFTERNOON THROUGH MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM WEDNESDAY...LIGHT WINDS AND 2-3 FT SEAS SHOULD
CONTINUE OVERNIGHT. SHOWERS SHOULD INCREASE IN COVERAGE ACROSS THE
WATERS MAINLY SOUTH OF CAPE FEAR AFTER MIDNIGHT. PREVIOUS DISCUSSION
FROM 730 PM FOLLOWS...
A SLOW-MOVING COLD FRONT NEAR CAPE LOOKOUT AND SHOULD DROP SOUTH
INTO THE CAPE FEAR/MYRTLE BEACH AREA OVERNIGHT...BUT WITH VERY
LITTLE FANFARE. LIGHT GENERALLY SOUTH TO SOUTHWEST WINDS NOW WILL
VEER TO THE WEST...THEN TO THE NORTH TO NORTHEAST LATE. WIND SPEEDS
SHOULD REMAIN BELOW 10 KNOTS REGARDLESS.
ONE WAVE OF SHOWERS AND EMBEDDED THUNDERSTORMS IS WORKING ITS WAY
OFFSHORE CURRENTLY. THERE SHOULD BE A 3-4 HOUR LULL BEHIND THESE
SHOWERS BEFORE A SECOND WAVE OF SHOWERS DEVELOPS ACROSS EASTERN
SOUTH CAROLINA AND MOVES OFFSHORE AFTER MIDNIGHT.
SEAS RANGE FROM 2-3 FT...AND THE BIGGEST CHANGE IN OUR FORECAST WAS
TO REMOVE ANY 1-FOOT SEAS FROM THE NEARSHORE WATERS BASED ON
OBSERVATIONS FROM THE OCEAN CREST PIER WAVE GAUGE AND AREA SURFCAMS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...EXPECT TO SEE E TO NE WINDS AROUND 10 KT
THURSDAY MORNING GRADUALLY VEER TO THE SOUTH BY FRIDAY EVENING AND
REMAIN AROUND 10 KT OR LESS WITH A WEAK GRADIENT IN PLACE. SEAS
SHOULD REMAIN 3 FT OR LESS THROUGH THE PERIOD.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...A SURFACE RIDGE CENTERED SOUTHEAST OF CAPE
FEAR SATURDAY WILL COMBINE WITH A TROUGH ACROSS THE SANDHILLS AND
PEE DEE REGION TO PRODUCE SOUTHWESTERLY FLOW OVER THE WATERS. THE
INLAND TROUGH WILL WEAKEN ON SUNDAY...AND AS A RESULT...FLOW WILL
BACK MORE TOWARDS THE SOUTH. THE GRADIENT MAY TIGHTEN SLIGHTLY
MONDAY AS THE FRONT GETS CLOSERS TO THE AREA. SPEEDS ARE EXPECTED TO
REMAIN 15 KT OR LESS THROUGH THE PERIOD AS A RESULT OF A RELATIVELY
BENIGN PRESSURE GRADIENT.
&&
.TIDES/COASTAL FLOODING...
INCREASING ASTRONOMICAL TIDES WILL BRING STANDING WATER TO
PORTIONS OF DOWNTOWN WILMINGTON ALONG THE CAPE FEAR RIVER AT HIGH
TIDE THIS EVENING...MAINLY BETWEEN 600 PM AND 900 PM. AS A RESULT
A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR INLAND NEW HANOVER
COUNTY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 6 PM TO 11 PM EDT THIS EVENING FOR
NCZ107.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...31
LONG TERM...CRM
AVIATION...MRR
TIDES/COASTAL FLOODING...HAWKINS
AREA FORECAST DISCUSSION
NWS TULSA OK
621 AM CDT FRI AUG 31 2012
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
FOR THE 12Z TAFS... REMNANTS OF TROPICAL SYSTEM ISAAC WILL
CONTINUE MOVING NORTHWARD THROUGH WESTERN ARKANSAS TODAY. OUR ARKANSAS
TAF SITES WILL LIKELY EXPERIENCE IFR CEILINGS WITH RAINFALL AND
WINDS INTERMITTENTLY THROUGHOUT MUCH OF THE DAY. IT IS UNCERTAIN
HOW FAR WEST THE EFFECTS OD ISAAC WILL BE FELT. OKLAHOMA TAF SITES
MAY EXPERIENCE MVFR CEILINGS ALONG WITH RAIN AND SOME WINDS.
&&
.PREV DISCUSSION... /ISSUED 348 AM CDT FRI AUG 31 2012/
DISCUSSION...
REMAINS OF ISAAC ARE CURRENTLY ALONG THE MONTGOMERY/SCOTT COUNTY LINE
IN SWRN AR...AND HAS SHOWN A NNW MOVEMENT OVER THE PAST SEVERAL
HOURS. THE BULK OF THE RAINFALL HAS REMAINED E AND N OF THE
CIRCULATION CENTER...ALTHOUGH HAVE RECENTLY SEEN A NARROW BAND
FAR NERN OK. 06Z NAM SEEMS TO HAVE A REASONABLE HANDLE ON THE TRACK
OF ISAAC...TAKING IT TO JUST E OF FORT SMITH EARLY THIS
MORNING...THEN EVENTUALLY INTO SWRN MO EARLY THIS AFTERNOON.
PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS ARE A GIVEN ACROSS NWRN
AR...ALTHOUGH POP FORECAST IS QUITE A BIT TRICKIER FARTHER W INTO
ERN OK. NAM AND HRRR BOTH SUGGEST THAT A FEW BANDS OF HEAVIER
SHOWERS COULD EVENTUALLY WRAP BACK DEEPER INTO NERN OK...AND GIVEN
THE RECENT TRENDS...HAVE OPTED TO MAINTAIN THE HIGH POPS FROM THE
PREVIOUS FORECAST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE
POSSIBLE ACROSS NWRN AR...ALTHOUGH RECENT DROUGHT CONDITIONS SHOULD
KEEP THE FLOODING POTENTIAL ON THE LOW END. SEVERE WEATHER THREAT
APPEARS MINIMAL AS WELL...WITH THE BEST CHANCES TODAY JUST E OF OUR
FORECAST AREA.
WIND GUSTS HAVE GENERALLY REMAINED BELOW 30-35 MPH OVERNIGHT. WHILE
AN ISOLATED 40 MPH GUST ISNT OUT OF THE QUESTION THIS MORNING...PLAN
ON DROPPING THE WIND ADVISORY WITH THE 4 AM FORECAST PACKAGE.
CIRCULATION CENTER WILL EVENTUALLY PULL NE OF THE REGION TONIGHT
INTO SATURDAY...WITH POPS GENERALLY TAPERING OFF BY LATE IN THE DAY.
MID-LEVEL RIDGING WILL BUILD BACK ACROSS THE SRN PLAINS THIS WEEKEND
AND INTO EARLY NEXT WEEK. EXPECT AFTERNOON TEMPS TO WARM BACK ABOVE
NORMALS...WITH READINGS PUSHING 100F IN SEVERAL SPOTS SUNDAY AND
MONDAY.
THE UPPER RIDGE FLATTENS A BIT BY MID-TO-LATE WEEK...PUTTING
OUR AREA ALONG THE SRN EDGE OF THE WESTERLIES. WILL KEEP
SHOWER/THUNDERSTORM CHANCES AROUND 20/30 PERCENT FOR NOW...ALTHOUGH
THESE NUMBERS MAY GO UP IF GFS REMAINS CONSISTENT WITH POTENTIAL MCS
SETUP WEDNESDAY NIGHT INTO THURSDAY.
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
AVIATION...06
AREA FORECAST DISCUSSION
NWS TULSA OK
348 AM CDT FRI AUG 31 2012
.DISCUSSION...
REMAINS OF ISAAC ARE CURRENTLY ALONG THE MONTGOMERY/SCOTT COUNTY LINE
IN SWRN AR...AND HAS SHOWN A NNW MOVEMENT OVER THE PAST SEVERAL
HOURS. THE BULK OF THE RAINFALL HAS REMAINED E AND N OF THE
CIRCULATION CENTER...ALTHOUGH HAVE RECENTLY SEEN A NARROW BAND
FAR NERN OK. 06Z NAM SEEMS TO HAVE A REASONABLE HANDLE ON THE TRACK
OF ISAAC...TAKING IT TO JUST E OF FORT SMITH EARLY THIS
MORNING...THEN EVENTUALLY INTO SWRN MO EARLY THIS AFTERNOON.
PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS ARE A GIVEN ACROSS NWRN
AR...ALTHOUGH POP FORECAST IS QUITE A BIT TRICKIER FARTHER W INTO
ERN OK. NAM AND HRRR BOTH SUGGEST THAT A FEW BANDS OF HEAVIER
SHOWERS COULD EVENTUALLY WRAP BACK DEEPER INTO NERN OK...AND GIVEN
THE RECENT TRENDS...HAVE OPTED TO MAINTAIN THE HIGH POPS FROM THE
PREVIOUS FORECAST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE
POSSIBLE ACROSS NWRN AR...ALTHOUGH RECENT DROUGHT CONDITIONS SHOULD
KEEP THE FLOODING POTENTIAL ON THE LOW END. SEVERE WEATHER THREAT
APPEARS MINIMAL AS WELL...WITH THE BEST CHANCES TODAY JUST E OF OUR
FORECAST AREA.
WIND GUSTS HAVE GENERALLY REMAINED BELOW 30-35 MPH OVERNIGHT. WHILE
AN ISOLATED 40 MPH GUST ISNT OUT OF THE QUESTION THIS MORNING...PLAN
ON DROPPING THE WIND ADVISORY WITH THE 4 AM FORECAST PACKAGE.
CIRCULATION CENTER WILL EVENTUALLY PULL NE OF THE REGION TONIGHT
INTO SATURDAY...WITH POPS GENERALLY TAPERING OFF BY LATE IN THE DAY.
MID-LEVEL RIDGING WILL BUILD BACK ACROSS THE SRN PLAINS THIS WEEKEND
AND INTO EARLY NEXT WEEK. EXPECT AFTERNOON TEMPS TO WARM BACK ABOVE
NORMALS...WITH READINGS PUSHING 100F IN SEVERAL SPOTS SUNDAY AND
MONDAY.
THE UPPER RIDGE FLATTENS A BIT BY MID-TO-LATE WEEK...PUTTING
OUR AREA ALONG THE SRN EDGE OF THE WESTERLIES. WILL KEEP
SHOWER/THUNDERSTORM CHANCES AROUND 20/30 PERCENT FOR NOW...ALTHOUGH
THESE NUMBERS MAY GO UP IF GFS REMAINS CONSISTENT WITH POTENTIAL MCS
SETUP WEDNESDAY NIGHT INTO THURSDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 84 73 93 72 / 80 30 20 10
FSM 85 73 94 73 / 90 50 30 10
MLC 90 74 97 73 / 40 20 10 10
BVO 85 70 92 68 / 80 30 20 10
FYV 81 73 90 68 / 100 70 40 20
BYV 80 71 88 69 / 100 70 50 20
MKO 85 71 94 71 / 80 40 20 10
MIO 81 73 89 71 / 90 60 40 20
F10 88 73 95 74 / 40 20 10 10
HHW 93 74 95 74 / 20 20 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...06
LONG TERM....18
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1223 AM CDT FRI AUG 31 2012
.UPDATE...
THE AVIATION DISCUSSION HAS BEEN UPDATED FOR THE 06Z TAF ISSUANCE.
00Z 300/500MB ANALYSIS INDICATED A LARGE UPPER RIDGE OVER THE
CENTRAL CONUS WITH A TROUGH OF LOW PRESSURE OVER THE PAC NW. THE
REMNANTS OF ISAAC WERE LIFTING NEWD THRU THE LOWER/MID MISSISSIPPI
VALLEY. AT THE SFC...HIGH PRESSURE CENTERED OVER ND IS EXPECTED
TO BUILD S/SEWD OVERNIGHT. SFC DEWPOINTS THIS EVENING ARE RANGING
FROM THE LOWER 50S OVER NERN SD...DOWN TO THE MIDDLE 30S OVER
CENTRAL AND WRN SD.
TEMPERATURES EARLY THIS EVENING ARE DROPPING OFF PRETTY QUICKLY
DUE TO THE DRY AIRMASS...AND MOSTLY CLEAR SKIES. HOWEVER...LATEST
IR SATELLITE IMAGERY INDICATES A FAIRLY WIDESPREAD AREA OF MID
LEVEL CLOUDINESS ADVECTING INTO THE AREA FROM THE SW IN THE RIGHT
ENTRANCE REGION OF THE UPPER JET. IN FACT KVTN ACTUALLY REPORTED
LIGHT RAIN/SPRINKLES...WHICH IS PRETTY AMAZING CONSIDERING THE
VERY DRY AMS EVIDENT IN THE KLBF 00Z RAOB. ALSO INTERESTING TO
NOTE THAT THE 22Z HRRR INDICATES A FEW SPRINKLES MOVING INTO THE FAR
SW LATER TONIGHT. WILL LEAVE FORECAST DRY FOR NOW DUE TO VERY DRY
AIR AT LOW LEVELS...BUT A FEW SPRINKLES/LIGHT SHOWERS ARE
POSSIBLE. TOUGH CALL ON HOW LOW TO GO WITH LOW TEMPERATURES AS
WELL. DECIDED TO DROP LOW TEMPERATURES A FEW DEGREES IN THE
EAST...BEFORE THICKER CLOUD COVER MOVES IN AFTER 06Z. UPDATES
OUT...
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
SPRINKLES AND DRY LIGHTNING CONTINUE FROM WEST CENTRAL MN
SOUTHWEST INTO SOUTH CENTRAL SD THIS AFTERNOON BEHIND A TRAILING
COLD FRONT. THIS ACTIVITY IS EXPECTED TO EXIT THE REGION OVER THE
NEXT 2 TO 3 HRS. HIGH PRESSURE WILL BUILD IN OVERNIGHT BRINGING
DRY CONDITIONS AND ABOVE AVERAGE TEMPERATURES THROUGH SATURDAY.
A LLJ WILL DEVELOP OVER THE WESTERN CWA EARLY ON SATURDAY MORNING.
DECIDED NOT TO MENTION POSSIBILITY OF PRECIP AT THIS POINT BECAUSE
LOWER LEVELS WILL BE VERY DRY...AND BEST FORCING WILL BE IN ND.
WINDS WILL INCREASE AHEAD OF THE LEE SIDE TROF FRIDAY AND
SATURDAY. MAY NEED TO ISSUE FIRE WEATHER HEADLINES...ESPECIALLY ON
SATURDAY.
AS THE COLD FRONT MOVES OFF THE ROCKIES SAT EVENING...MODELS ARE
BEGINNING TO DIVERGE FROM PREVIOUS SOLUTIONS. CURRENT RUNS TRACK
THE BULK OF PRECIP OVER ND NOW ON SAT NIGHT. LEFT SOME ISOLATED
POPS ACROSS WESTERN CORSON COUNTY SAT NIGHT BUT MAY NEED TO REMOVE
THESE AS WELL IF MODELS CONTINUE THIS TREND.
HIGHS WILL CLIMB BACK INTO THE 90S OVER THE WEEKEND...ABOUT 10
DEGREES ABOVE AVERAGE IN MOST LOCATIONS.
.LONG TERM...SUNDAY THROUGH THURSDAY
SUNDAY INTO SUNDAY EVENING MODELS ARE CONSISTENT IN SHOWING A WEAK
SFC TROUGH PASSING THROUGH THE AREA...ALTHOUGH MOISTURE AVAILABLE
FOR THIS FEATURE IS RATHER LIMITED. WILL CONTINUE WITH LOW POPS
FOR THE EASTERN CWA SUNDAY INTO SUNDAY NIGHT. BY THE MIDDLE OF THE
WEEK A MORE SIGNIFICANT SHORTWAVE MOVES ACROSS THE AREA AND THE
INHERITED GUIDANCE POPS LOOKED OK FOR THIS POTENTIAL EVENT FOR THE
TIME BEING. THERE ARE STILL TIMING AND PLACEMENT ISSUES WITH THE
MIDDLE OF THE WEEK SYSTEM SO DID NOT STRAY TOO FAR FROM GUIDANCE
AT THIS POINT. TEMPS LOOK TO STAY RATHER WARM THROUGH THE PERIOD
WITH A SLIGHT COOL DOWN TOWARDS THE END OF NEXT WEEK PERHAPS.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS WILL PREVAIL THE NEXT 24 HOURS. SATELLITE IMAGERY
INDICATING INCREASING MID-LEVEL CLOUDS FROM THE SOUTHWEST...AND
THIS BROKEN DECK OF CLOUDINESS IS EXPECTED TO PERSIST THROUGH MUCH
OF FRIDAY. A FEW SPRINKLES ARE POSSIBLE OVERNIGHT BUT IMPACTS WILL BE
MINIMAL. LIGHT NORTHEAST WINDS OVERNIGHT WILL BECOME E/SELY ON
FRIDAY AS HIGH PRESSURE SLIDES EAST OF THE AREA. A TIGHTER SFC
GRADIENT WILL RESULT IN BREEZY CONDITIONS AFTER 17Z AT
KPIR/KMBG...WITH A FEW GUSTS AROUND 25 KTS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...FOWLE
SHORT TERM...WISE
LONG TERM...TMT
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
845 PM CDT THU AUG 30 2012
.UPDATE...
00Z 300/500MB ANALYSIS INDICATED A LARGE UPPER RIDGE OVER THE
CENTRAL CONUS WITH A TROUGH OF LOW PRESSURE OVER THE PAC NW. THE
REMNANTS OF ISAAC WERE LIFTING NWD THRU THE LOWER/MID MISSISSIPPI
VALLEY. AT THE SFC...HIGH PRESSURE CENTERED OVER ND IS EXPECTED
TO BUILD S/SEWD OVERNIGHT. SFC DEWPOINTS THIS EVENING ARE RANGING
FROM THE LOWER 50S OVER NERN SD...DOWN TO THE MIDDLE 30S OVER
CENTRAL AND WRN SD.
TEMPERATURES EARLY THIS EVENING ARE DROPPING OFF PRETTY QUICKLY
DUE TO THE DRY AIRMASS...AND MOSTLY CLEAR SKIES. HOWEVER...LATEST
IR SATELLITE IMAGERY INDICATES A FAIRLY WIDESPREAD AREA OF MID
LEVEL CLOUDINESS ADVECTING INTO THE AREA FROM THE SW IN THE RIGHT
ENTRANCE REGION OF THE UPPER JET. IN FACT KVTN ACTUALLY REPORTED
LIGHT RAIN/SPRINKLES...WHICH IS PRETTY AMAZING CONSIDERING THE
VERY DRY AMS EVIDENT IN THE KLBF 00Z RAOB. ALSO INTERESTING TO
NOTE THAT THE 22Z HRRR INDICATES A FEW SPRINKLES MOVING INTO THE FAR
SW LATER TONIGHT. WILL LEAVE FORECAST DRY FOR NOW DUE TO VERY DRY
AIR AT LOW LEVELS...BUT A FEW SPRINKLES/LIGHT SHOWERS ARE
POSSIBLE. TOUGH CALL ON HOW LOW TO GO WITH LOW TEMPERATURES AS
WELL. DECIDED TO DROP LOW TEMPERATURES A FEW DEGREES IN THE
EAST...BEFORE THICKER CLOUD COVER MOVES IN AFTER 06Z. UPDATES
OUT...
FOWLE
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
SPRINKLES AND DRY LIGHTNING CONTINUE FROM WEST CENTRAL MN
SOUTHWEST INTO SOUTH CENTRAL SD THIS AFTERNOON BEHIND A TRAILING
COLD FRONT. THIS ACTIVITY IS EXPECTED TO EXIT THE REGION OVER THE
NEXT 2 TO 3 HRS. HIGH PRESSURE WILL BUILD IN OVERNIGHT BRINGING
DRY CONDITIONS AND ABOVE AVERAGE TEMPERATURES THROUGH SATURDAY.
A LLJ WILL DEVELOP OVER THE WESTERN CWA EARLY ON SATURDAY MORNING.
DECIDED NOT TO MENTION POSSIBILITY OF PRECIP AT THIS POINT BECAUSE
LOWER LEVELS WILL BE VERY DRY...AND BEST FORCING WILL BE IN ND.
WINDS WILL INCREASE AHEAD OF THE LEE SIDE TROF FRIDAY AND
SATURDAY. MAY NEED TO ISSUE FIRE WEATHER HEADLINES...ESPECIALLY ON
SATURDAY.
AS THE COLD FRONT MOVES OFF THE ROCKIES SAT EVENING...MODELS ARE
BEGINNING TO DIVERGE FROM PREVIOUS SOLUTIONS. CURRENT RUNS TRACK
THE BULK OF PRECIP OVER ND NOW ON SAT NIGHT. LEFT SOME ISOLATED
POPS ACROSS WESTERN CORSON COUNTY SAT NIGHT BUT MAY NEED TO REMOVE
THESE AS WELL IF MODELS CONTINUE THIS TREND.
HIGHS WILL CLIMB BACK INTO THE 90S OVER THE WEEKEND...ABOUT 10
DEGREES ABOVE AVERAGE IN MOST LOCATIONS.
.LONG TERM...SUNDAY THROUGH THURSDAY
SUNDAY INTO SUNDAY EVENING MODELS ARE CONSISTENT IN SHOWING A WEAK
SFC TROUGH PASSING THROUGH THE AREA...ALTHOUGH MOISTURE AVAILABLE
FOR THIS FEATURE IS RATHER LIMITED. WILL CONTINUE WITH LOW POPS
FOR THE EASTERN CWA SUNDAY INTO SUNDAY NIGHT. BY THE MIDDLE OF THE
WEEK A MORE SIGNIFICANT SHORTWAVE MOVES ACROSS THE AREA AND THE
INHERITED GUIDANCE POPS LOOKED OK FOR THIS POTENTIAL EVENT FOR THE
TIME BEING. THERE ARE STILL TIMING AND PLACEMENT ISSUES WITH THE
MIDDLE OF THE WEEK SYSTEM SO DID NOT STRAY TOO FAR FROM GUIDANCE
AT THIS POINT. TEMPS LOOK TO STAY RATHER WARM THROUGH THE PERIOD
WITH A SLIGHT COOL DOWN TOWARDS THE END OF NEXT WEEK PERHAPS.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS WILL PREVAIL THROUGH THE NEXT 24 HOURS. EXPECTING
AN INCREASE IN MAINLY MID LEVEL CLOUDINESS OVERNIGHT...ALTHOUGH
CIGS WILL BE AOA 12K FEET AGL. LIGHT NORTHEAST WINDS OVERNIGHT
WILL BECOME E/SELY ON FRIDAY AS HIGH PRESSURE SLIDES EAST OF THE
AREA.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...FOWLE
SHORT TERM...WISE
LONG TERM...TMT
AVIATION...FOWLE
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1233 PM CDT THU AUG 30 2012
.DISCUSSION.../ISSUED AT 1048 AM CDT/
FORECAST FOR TODAY GENERALLY LOOKS IN GOOD SHAPE. LATEST HI RES NAM
AND HRRR IN GOOD AGREEMENT ON FRONTAL TIMING...ADDING CONFIDENCE TO
THIS AFTERNOONS FORECAST. FRONT IS CURRENTLY THROUGH HURON AND
CHAMBERLAIN. THINKING IT PUSHES THROUGH MITCHELL SHORTLY...SIOUX
FALLS AROUND 20Z...YANKTON AROUND 22Z AND NOT REACHING SIOUX CITY OR
SPENCER UNTIL 0Z OR LATER. MID LEVEL CLOUDS AHEAD OF THE FRONT ARE
DISSIPATING...SO NOT THINKING THEY WILL HAVE TOO BIG OF AN IMPACT ON
HIGH TEMPERATURES. MADE SOME MINOR ADJUSTMENTS TO HIGHS...MAINLY
DROPPED THEM A FEW DEGREES IN THE NORTHWEST BEHIND THE FRONT...AND
WARMED THEM A BIT NEAR YANKTON. OUTFLOW FROM CONVECTION IN NORTHEAST
SOUTH DAKOTA HAS PUSHED SOUTH INTO SOUTHWEST MINNESOTA. DESPITE THIS
BEING A LOW LEVEL BOUNDARY...THE ATMOSPHERE IS UNSTABLE ENOUGH THAT
IT HAS TRIGGERED CLOUDS TO FORM UP AT 15000 FEET. THESE CLOUDS
WILL LIKELY HOLD TEMPERATURES DOWN SOME THERE...BUT THEY SHOULD ALSO
TEND TO DISSIPATE INTO EARLY AFTERNOON.
WINDS LIKELY TO BE GUSTING TO 30 MPH AHEAD OF THE FRONT THIS
AFTERNOON OUT OF THE SOUTH...WITH GUSTS UP TO 20 MPH OUT OF THE
NORTH BEHIND IT. FIRE WEATHER HEADLINES LOOK GOOD. RH VALUES
EXPECTED TO DROP BELOW 20 PERCENT AHEAD OF THE FRONT. IN SOUTHWEST
MINNESOTA...LOOKING LIKE ONLY THE SOUTHERN TIER OF COUNTIES ARE
GOING TO REACH CRITERIA BEFORE THE FRONT PUSHES THROUGH. /CHENARD
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. A FEW LIGHT SHOWERS
WILL BE POSSIBLE INTO EARLY THIS AFTERNOON FROM 9V9 THROUGH ATY.
SOUTHWEST WINDS WILL GUST AROUND 30 FROM ABOUT SIOUX FALLS SOUTH AND
EAST AHEAD OF AN INCOMING DRY COOL FRONT. WINDS WILL SHIFT TO THE
NORTH BEHIND THE BOUNDARY...WITH GUSTS AROUND 20 MPH POSSIBLE. WINDS
WILL CALM DOWN TONIGHT...AND WILL BE A BIT BREEZY TOMORROW OUT OF
THE EAST NORTH OF THE BOUNDARY. FRONTAL TIMING LOOKS LIKE AROUND 20Z
IN SIOUX FALLS. FRONT WILL WASH OUT BY THE TIME IT APPROACHES SIOUX
CITY...THUS MAINLY LIGHT AND VARIABLE WINDS EXPECTED THERE FOR
TONIGHT INTO TOMORROW MORNING. /CHENARD
&&
.PREVIOUS DISCUSSION.../ISSUED AT 455 AM CDT/
FIRE WEATHER CONCERNS ONCE AGAIN AT FOREFRONT THIS MORNING...AFTER
YESTERDAY WHICH FEATURED EXTREME CONDITIONS THROUGH THE MISSOURI
RIVER VALLEY AND LOESS HILLS REGION. GENERAL DISCUSSION FOLLOWS...
WITH DETAILS BELOW IN FIRE WEATHER SECTION.
TAIL END OF WEAK WAVE BRUSHING THROUGH NORTHERN SOUTH DAKOTA AND
DRIVING A FRONTAL BOUNDARY SOUTHWARD...AT 09Z ON A LINE FROM
SOUTHEAST NORTH DAKOTA TO SOUTHWEST SOUTH DAKOTA. STRONG LOW LEVEL
JET ESTABLISHED OVERNIGHT ACROSS THE AREA AHEAD OF THIS BOUNDARY...
AS WARM FRONT ROCKETED NORTHWARD. HIGHER ELEVATIONS SITES IN SOUTH
CENTRAL SOUTH DAKOTA HAVE STRUGGLED TO DROP BELOW THE MID 80S THUS
FAR...AND WINDS ON AND DOWNSTREAM OF THE BUFFALO RIDGE NOW GUSTING
TO 25 TO 35 KNOTS. LOW LEVEL DRY AIR ALREADY ESTABLISHED IN MIXY
ENVIRONMENT...WITH 30S TO LOWER 40S DEWPOINTS IN THE WEST...AND
A PARTIALLY DECOUPLED AIRSTREAM IN THE EAST STRUGGLING TO MAINTAIN
NEAR 60 VALUES. NAM AGAIN IS THE FAST OUTLIER WITH BOUNDARY...
SOMEWHAT SLOWER THAN YESTERDAY...AND PREFER A ECMWF/GFS BLEND FOR
TIMING. THIS WOULD PUT FRONT THROUGH THE SIOUX FALLS AREA EARLY
AFTERNOON...RATHER THAN MID MORNING. RESULT WILL BE ANOTHER
SCORCHER ACROSS THE AREA WITH ADDITIONAL RECORD TEMPERATURES.
WARMEST READINGS FOR TODAY SEEM TO BE FOCUSING ONTO THE LOWER
MISSOURI VALLEY AROUND KSUX...EXTENDING TOWARD KCKP/KSPW
AREAS...WHERE EXPECT 100 TO 105 DEGREE READINGS. MORE EXTENSIVE MID
TO HIGH CLOUDS ACROSS THE WEST AND NORTH WILL PUT SOME CONTROL ON
TEMPS...BUT WITH WAVE PUSHING PAST...SHOULD THIN OUT SOMEWHAT FOR
THE AFTERNOON. EVEN THEN...WILL LIKELY STRUGGLE TO 90 DEGREES IN THE
NORTHWEST...AND ACTUALLY FIND SOME TEMPS DROPPING BACK A BIT DURING
THE AFTERNOON BASED ON MIXING POTENTIAL.
FRONT WILL SLOW BUT CONTINUE TO PUSH THROUGH THE CWA THIS EVENING...
WITH AN EASTERLY FLOW REGIME BECOMING ESTABLISHED ON FRIDAY. RIDGE
WILL AGAIN STRENGTHEN A BIT BETWEEN WESTERLIES TO NORTH AND TROPICAL
REMNANTS OF ISAAC TO THE SOUTH. SHOULD HAVE MORE SUNSHINE...BUT
THE EXTREME WARMTH OF LAST COUPLE DAYS AND TODAY WILL BE REPLACED BY
JUST YOUR TYPICAL ABOVE NORMAL READINGS.
SATURDAY...REMNANTS OF ISAAC WILL TAKE A WIDE RIGHT PASS...BUT SOME
LOW LEVEL TRAJECTORIES SUGGEST MAY BE ABLE TO BLEED OFF A SOMEWHAT
ENHANCED DEWPOINT THROUGH THE EASTERN CWA...LIKELY RESULTS IN SOME
FLAT CUMULUS DEVELOPMENT...AND SLIGHTLY COOLER TEMPERATURES.
IN THE EXTENDED RANGE /SUNDAY THROUGH WEDNESDAY/
ECMWF HAS FLIPPED TO A MUCH WEAKER MONDAY WAVE...AND INSTEAD PUT ITS
EGGS IN THE SECONDARY BASKET WITH IMPRESSIVELY SHARP TROUGH ON
WEDNESDAY. GFS...WHILE AT ODDS WITH A FAIR POPULATION OF ITS OWN
ENSEMBLES...SUGGESTS A STRONGER INITIAL TROUGH ON MONDAY AND DRIVES
BOUNDARY WELL SOUTH THROUGH THE UPCOMING WEEK...SOMEWHAT COOLER...
AND CERTAINLY DRY. WITH AS MUCH CONSTERNATION AS THE MODELS HAVE HAD
WITH UPCOMING LARGER SCALE PATTERN...DID NOT ALTER EXTENDED AS MUCH
AS MIGHT HAVE...OTHER THAN THE USUAL STRETCHING OF DIURNAL RANGES A
BIT...AND HACKING OUT SOME OF THE SLIGHT CHANCE POPS RESULTING FROM
THE BLENDING OF WIDELY VARYING SOLUTIONS. THROUGH SUNDAY...ENOUGH
AGREEMENT TO SUGGEST NUDGING HIGHS UP A BIT THROUGH THE WEST/MID
PORTIONS OF CWA AHEAD OF NEXT FRONTAL BOUNDARY. NOT A GREAT DEAL
OF DEEPER FORCING DOWN TOWARD OUR END OF THE FRONT...SO KEPT POPS
LIMITED TO LOWER CHANCE AND THROUGH THE NORTH/EAST AREAS FROM LATE
AFTERNOON THROUGH EVENING HOURS. POTENTIALLY ENOUGH SHEAR AND WITH
SOME INCREASED MOISTURE LINGERING...MAY GET 1000-1500 J/KG MLCAPE
AND ENOUGH SHEAR TO HAVE A LIMITED SEVERE THREAT. /CHAPMAN
&&
.FIRE WEATHER...
WITH LITTLE QUESTION TO THE EXTENT OF DRY AIRMASS SITTING ACROSS THE
AREA ALREADY THIS MORNING WITH MID 30S TO LOWER 40S DEWPOINTS ACROSS
CENTRAL NEBRASKA AND A VASTLY DRY KLBF RAOB FROM LAST EVENING...
SIGNIFICANT ISSUE FOR THE ISSUANCE OF RED FLAG WARNING IS PROGRESSION
OF THE FRONTAL BOUNDARY AND MIXING OF WINDS AHEAD OF THIS BOUNDARY.
PROFILER WINDS AT NLG SUPPORT STRONG PREFRONTAL LOW LEVEL JET...
AND HAVE SEEN HIGHER ELEVATION SITES CONTINUE TO REPORT 20 TO 30
KNOTS GUSTS OVERNIGHT. THEREFORE...LITTLE DOUBT IN WINDS AS WEAK
WAVE PASSING NORTH CONTINUES TO SUPPORT LOW LEVEL JET WITH A SLOW
WEAKENING TREND THROUGH MIDDAY. THIS SHOULD BE BALANCED SOMEWHAT BY
THE QUICK AND DEEPER MIXING. LOWEST HUMIDITY AREA OF LESS THAN 20
PERCENT IS GENERAL OUTLINE USED FOR ISSUANCE OF RED FLAG WARNING...
WITH SUSTAINED WINDS PROBABLY OVERALL TECHNICALLY JUST A BIT UNDER
FOR MOST...BUT ENOUGH FOR FREQUENT GUSTS AT OF ABOVE 25 KNOTS.
FOR THE TWO ADDITIONS IN SOUTHEAST SOUTH DAKOTA AND SOUTHWEST
MINNESOTA...IT IS REALLY ONLY THE SOUTHEAST PORTIONS OF THOSE AREAS
OF GREATEST CONCERN. IT ALSO IS POSSIBLE THAT A COUPLE HOURS WILL
APPROACH OR EXCEED CRITERIA RIGHT AROUND KFSD...BUT WITH MUCH LESS
AREA IN THIS ZONE THAT MAY BE IMPACTED BEFORE WINDS DROP OFF
ENOUGH...WILL KEEP CLEAR OF A RED FLAG WARNING FOR NOW. DID END THE
NORTHERNMOST GROUPS A COUPLE HOURS EARLIER TO ACCOUNT FOR THE
BOUNDARY AND EARLIER LOSS OF GRADIENT. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...RED FLAG WARNING FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
IAZ300-301.
MN...RED FLAG WARNING FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
MNZ900.
NE...RED FLAG WARNING FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
NEZ249.
SD...RED FLAG WARNING FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
SDZ258.
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1048 AM CDT THU AUG 30 2012
.DISCUSSION.../ISSUED AT 1048 AM CDT/
FORECAST FOR TODAY GENERALLY LOOKS IN GOOD SHAPE. LATEST HI RES NAM
AND HRRR IN GOOD AGREEMENT ON FRONTAL TIMING...ADDING CONFIDENCE TO
THIS AFTERNOONS FORECAST. FRONT IS CURRENTLY THROUGH HURON AND
CHAMBERLAIN. THINKING IT PUSHES THROUGH MITCHELL SHORTLY...SIOUX
FALLS AROUND 20Z...YANKTON AROUND 22Z AND NOT REACHING SIOUX CITY OR
SPENCER UNTIL 0Z OR LATER. MID LEVEL CLOUDS AHEAD OF THE FRONT ARE
DISSIPATING...SO NOT THINKING THEY WILL HAVE TOO BIG OF AN IMPACT ON
HIGH TEMPERATURES. MADE SOME MINOR ADJUSTMENTS TO HIGHS...MAINLY
DROPPED THEM A FEW DEGREES IN THE NORTHWEST BEHIND THE FRONT...AND
WARMED THEM A BIT NEAR YANKTON. OUTFLOW FROM CONVECTION IN NORTHEAST
SOUTH DAKOTA HAS PUSHED SOUTH INTO SOUTHWEST MINNESOTA. DESPITE THIS
BEING A LOW LEVEL BOUNDARY...THE ATMOSPHERE IS UNSTABLE ENOUGH THAT
IT HAS TRIGGERED CLOUDS TO FORM UP AT 15000 FEET. THESE CLOUDS
WILL LIKELY HOLD TEMPERATURES DOWN SOME THERE...BUT THEY SHOULD ALSO
TEND TO DISSIPATE INTO EARLY AFTERNOON.
WINDS LIKELY TO BE GUSTING TO 30 MPH AHEAD OF THE FRONT THIS
AFTERNOON OUT OF THE SOUTH...WITH GUSTS UP TO 20 MPH OUT OF THE
NORTH BEHIND IT. FIRE WEATHER HEADLINES LOOK GOOD. RH VALUES
EXPECTED TO DROP BELOW 20 PERCENT AHEAD OF THE FRONT. IN SOUTHWEST
MINNESOTA...LOOKING LIKE ONLY THE SOUTHERN TIER OF COUNTIES ARE
GOING TO REACH CRITERIA BEFORE THE FRONT PUSHES THROUGH. /CHENARD
.PREVIOUS DISCUSSION.../ISSUED AT 455 AM CDT/
FIRE WEATHER CONCERNS ONCE AGAIN AT FOREFRONT THIS MORNING...AFTER
YESTERDAY WHICH FEATURED EXTREME CONDITIONS THROUGH THE MISSOURI
RIVER VALLEY AND LOESS HILLS REGION. GENERAL DISCUSSION FOLLOWS...
WITH DETAILS BELOW IN FIRE WEATHER SECTION.
TAIL END OF WEAK WAVE BRUSHING THROUGH NORTHERN SOUTH DAKOTA AND
DRIVING A FRONTAL BOUNDARY SOUTHWARD...AT 09Z ON A LINE FROM
SOUTHEAST NORTH DAKOTA TO SOUTHWEST SOUTH DAKOTA. STRONG LOW LEVEL
JET ESTABLISHED OVERNIGHT ACROSS THE AREA AHEAD OF THIS BOUNDARY...
AS WARM FRONT ROCKETED NORTHWARD. HIGHER ELEVATIONS SITES IN SOUTH
CENTRAL SOUTH DAKOTA HAVE STRUGGLED TO DROP BELOW THE MID 80S THUS
FAR...AND WINDS ON AND DOWNSTREAM OF THE BUFFALO RIDGE NOW GUSTING
TO 25 TO 35 KNOTS. LOW LEVEL DRY AIR ALREADY ESTABLISHED IN MIXY
ENVIRONMENT...WITH 30S TO LOWER 40S DEWPOINTS IN THE WEST...AND
A PARTIALLY DECOUPLED AIRSTREAM IN THE EAST STRUGGLING TO MAINTAIN
NEAR 60 VALUES. NAM AGAIN IS THE FAST OUTLIER WITH BOUNDARY...
SOMEWHAT SLOWER THAN YESTERDAY...AND PREFER A ECMWF/GFS BLEND FOR
TIMING. THIS WOULD PUT FRONT THROUGH THE SIOUX FALLS AREA EARLY
AFTERNOON...RATHER THAN MID MORNING. RESULT WILL BE ANOTHER
SCORCHER ACROSS THE AREA WITH ADDITIONAL RECORD TEMPERATURES.
WARMEST READINGS FOR TODAY SEEM TO BE FOCUSING ONTO THE LOWER
MISSOURI VALLEY AROUND KSUX...EXTENDING TOWARD KCKP/KSPW
AREAS...WHERE EXPECT 100 TO 105 DEGREE READINGS. MORE EXTENSIVE MID
TO HIGH CLOUDS ACROSS THE WEST AND NORTH WILL PUT SOME CONTROL ON
TEMPS...BUT WITH WAVE PUSHING PAST...SHOULD THIN OUT SOMEWHAT FOR
THE AFTERNOON. EVEN THEN...WILL LIKELY STRUGGLE TO 90 DEGREES IN THE
NORTHWEST...AND ACTUALLY FIND SOME TEMPS DROPPING BACK A BIT DURING
THE AFTERNOON BASED ON MIXING POTENTIAL.
FRONT WILL SLOW BUT CONTINUE TO PUSH THROUGH THE CWA THIS EVENING...
WITH AN EASTERLY FLOW REGIME BECOMING ESTABLISHED ON FRIDAY. RIDGE
WILL AGAIN STRENGTHEN A BIT BETWEEN WESTERLIES TO NORTH AND TROPICAL
REMNANTS OF ISAAC TO THE SOUTH. SHOULD HAVE MORE SUNSHINE...BUT
THE EXTREME WARMTH OF LAST COUPLE DAYS AND TODAY WILL BE REPLACED BY
JUST YOUR TYPICAL ABOVE NORMAL READINGS.
SATURDAY...REMNANTS OF ISAAC WILL TAKE A WIDE RIGHT PASS...BUT SOME
LOW LEVEL TRAJECTORIES SUGGEST MAY BE ABLE TO BLEED OFF A SOMEWHAT
ENHANCED DEWPOINT THROUGH THE EASTERN CWA...LIKELY RESULTS IN SOME
FLAT CUMULUS DEVELOPMENT...AND SLIGHTLY COOLER TEMPERATURES.
IN THE EXTENDED RANGE /SUNDAY THROUGH WEDNESDAY/
ECMWF HAS FLIPPED TO A MUCH WEAKER MONDAY WAVE...AND INSTEAD PUT ITS
EGGS IN THE SECONDARY BASKET WITH IMPRESSIVELY SHARP TROUGH ON
WEDNESDAY. GFS...WHILE AT ODDS WITH A FAIR POPULATION OF ITS OWN
ENSEMBLES...SUGGESTS A STRONGER INITIAL TROUGH ON MONDAY AND DRIVES
BOUNDARY WELL SOUTH THROUGH THE UPCOMING WEEK...SOMEWHAT COOLER...
AND CERTAINLY DRY. WITH AS MUCH CONSTERNATION AS THE MODELS HAVE HAD
WITH UPCOMING LARGER SCALE PATTERN...DID NOT ALTER EXTENDED AS MUCH
AS MIGHT HAVE...OTHER THAN THE USUAL STRETCHING OF DIURNAL RANGES A
BIT...AND HACKING OUT SOME OF THE SLIGHT CHANCE POPS RESULTING FROM
THE BLENDING OF WIDELY VARYING SOLUTIONS. THROUGH SUNDAY...ENOUGH
AGREEMENT TO SUGGEST NUDGING HIGHS UP A BIT THROUGH THE WEST/MID
PORTIONS OF CWA AHEAD OF NEXT FRONTAL BOUNDARY. NOT A GREAT DEAL
OF DEEPER FORCING DOWN TOWARD OUR END OF THE FRONT...SO KEPT POPS
LIMITED TO LOWER CHANCE AND THROUGH THE NORTH/EAST AREAS FROM LATE
AFTERNOON THROUGH EVENING HOURS. POTENTIALLY ENOUGH SHEAR AND WITH
SOME INCREASED MOISTURE LINGERING...MAY GET 1000-1500 J/KG MLCAPE
AND ENOUGH SHEAR TO HAVE A LIMITED SEVERE THREAT. /CHAPMAN
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. A FEW SHOWERS AND
VERY ISOLATED THUNDERSTORMS WILL BE POSSIBLE THROUGH MID MORNING
FROM ABOUT 9V9 THROUGH ATY. SOUTHWEST WINDS COULD GUST AS HIGH AS 30
KNOTS FROM ABOUT SIOUX FALLS SOUTH AND EAST AHEAD OF AN INCOMING DRY
COOL FRONT. /08
&&
.FIRE WEATHER...
WITH LITTLE QUESTION TO THE EXTENT OF DRY AIRMASS SITTING ACROSS THE
AREA ALREADY THIS MORNING WITH MID 30S TO LOWER 40S DEWPOINTS ACROSS
CENTRAL NEBRASKA AND A VASTLY DRY KLBF RAOB FROM LAST EVENING...
SIGNIFICANT ISSUE FOR THE ISSUANCE OF RED FLAG WARNING IS PROGRESSION
OF THE FRONTAL BOUNDARY AND MIXING OF WINDS AHEAD OF THIS BOUNDARY.
PROFILER WINDS AT NLG SUPPORT STRONG PREFRONTAL LOW LEVEL JET...
AND HAVE SEEN HIGHER ELEVATION SITES CONTINUE TO REPORT 20 TO 30
KNOTS GUSTS OVERNIGHT. THEREFORE...LITTLE DOUBT IN WINDS AS WEAK
WAVE PASSING NORTH CONTINUES TO SUPPORT LOW LEVEL JET WITH A SLOW
WEAKENING TREND THROUGH MIDDAY. THIS SHOULD BE BALANCED SOMEWHAT BY
THE QUICK AND DEEPER MIXING. LOWEST HUMIDITY AREA OF LESS THAN 20
PERCENT IS GENERAL OUTLINE USED FOR ISSUANCE OF RED FLAG WARNING...
WITH SUSTAINED WINDS PROBABLY OVERALL TECHNICALLY JUST A BIT UNDER
FOR MOST...BUT ENOUGH FOR FREQUENT GUSTS AT OF ABOVE 25 KNOTS.
FOR THE TWO ADDITIONS IN SOUTHEAST SOUTH DAKOTA AND SOUTHWEST
MINNESOTA...IT IS REALLY ONLY THE SOUTHEAST PORTIONS OF THOSE AREAS
OF GREATEST CONCERN. IT ALSO IS POSSIBLE THAT A COUPLE HOURS WILL
APPROACH OR EXCEED CRITERIA RIGHT AROUND KFSD...BUT WITH MUCH LESS
AREA IN THIS ZONE THAT MAY BE IMPACTED BEFORE WINDS DROP OFF
ENOUGH...WILL KEEP CLEAR OF A RED FLAG WARNING FOR NOW. DID END THE
NORTHERNMOST GROUPS A COUPLE HOURS EARLIER TO ACCOUNT FOR THE
BOUNDARY AND EARLIER LOSS OF GRADIENT. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...RED FLAG WARNING FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
IAZ300-301.
MN...RED FLAG WARNING FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
MNZ900.
NE...RED FLAG WARNING FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
NEZ249.
SD...RED FLAG WARNING FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
SDZ258.
$$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1020 AM CDT THU AUG 30 2012
.DISCUSSION...
ISAAC WAS LOCATED IN NORTH-CENTRAL LOUISIANA AT MID MORNING WITH
SOME OF THE OUTER BANDS OF THE STORM MOVING ACROSS EAST TEXAS...
JUST TO THE EAST OF THE HGX FORECAST AREA. THE NAM AND RAP MODELS
BOTH BRING THE MORE MOIST AIRMASS INTO THE EASTERN COUNTIES OF THE
FORECAST AREA THIS AFTERNOON. THIS IMPLIES THAT THE OUTER BANDS
SHOULD MOVE ACROSS THESE AREAS. OTHERWISE...MOST OF SE TX WILL
EXPERIENCE HOT AND MOSTLY SUNNY CONDITIONS. THE CONTINUED OFFSHORE
WIND FLOW WILL KEEP THE WATER LEVELS LOW IN GALVESTON BAY WITH THE
LOWEST LEVELS LIKELY IN THE NORTHERN PORTIONS OF THE BAY AND IN
THE SHIP CHANNEL. IN PARTICULAR...MORGANS POINT HAS HAD WATER
LEVELS DOWN ALMOST 2 FEET BELOW THE EXPECTED MEAN LOWER LOW WATER.
FOR THE MOST PART...THE CURRENT FORECAST IS ON TRACK. ADJUSTED THE
WINDS DOWNWARD A BIT AND DROPPED THE MARINE HAZARDS WITH THE
EXCEPTION OF THE LOW WATER HAZARD IN GALVESTON BAY.
40
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 100 76 98 77 96 / 20 10 10 10 10
HOUSTON (IAH) 98 78 96 78 93 / 20 20 20 10 20
GALVESTON (GLS) 95 82 92 81 91 / 20 20 20 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...40
AVIATION/MARINE...47
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
632 PM CDT WED AUG 29 2012
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
309 PM CDT WED AUG 29 2012
MAIN FORECAST CONCERNS THIS PACKAGE...HEAT AND FIRE WEATHER CONCERNS
THU...ANY RAIN CHANCES FROM ISAAC SAT/SAT NIGHT.
18Z DATA ANALYSIS HAD A BROAD AREA OF LOW PRESSURE OVER THE NORTHERN
PLAINS. GRADIENT OVER MN/IA/WI WAS TIGHTENING AHEAD OF THIS FEATURE
WITH INCREASING SOUTHEAST TO SOUTHWEST WINDS OVER THE REGION.
SOUTHWEST FLOW OVER NEB/WESTERN IA ALONG WITH DEEP MIXING WAS
SPREADING DRIER AIR NORTHEAST INTO THE REGION...AND DEW POINTS WEST
OF I-35 AND SOUTH OF I-90 WERE FALLING INTO THE LOWER 50S.
OTHERWISE BROAD LOW LEVEL WARM ADVECTION AND PLENTY OF SUNSHINE WERE
HELPING EARLY AFTERNOON TEMPS CLIMB INTO THE UPPER 70S AND 80S MOST
OF THE UPPER MIDWEST.
29.12Z MODELS LOOK TO HAVE INITIALIZED WELL...BUT FOR GFS SOME 5F OR
SO TOO HIGH WITH SFC DEW POINT OVER MUCH OF THE MID/UPPER MS VALLEY
AND NORTHERN PLAINS. SOLUTIONS REASONABLY SIMILAR FOR THE UPPER
MIDWEST TONIGHT INTO FRI NIGHT AS A COLD FRONT SINKS SOUTH INTO/
ACROSS THE AREA...AT LEAST WITH SFC AND 500MB FEATURES. PLENTY OF
DIFFERENCES WITH SFC-925MB TEMPS/DEW POINTS ON THU. SOLUTIONS
DIVERGE ON HOW FAR WEST/NORTH THE REMNANTS OF ISAAC END UP BY FRI
AND BEYOND. DPROG/DT OF 500MB HGTS AT 29.12Z SHOWED MODEL RUNS OF
27.12Z AND 28.12Z VERIFIED REASONABLY WELL ACROSS NOAM. 27.12Z RUNS
WERE SLOW WITH THE SHORTWAVE MOVING THRU THE PAC NORTHWEST WHILE A
COMPROMISE/ CONSENSUS OF THE EARLIER RUNS WAS BEST WITH THE LOCATION
OF ISAAC. MODEL CONSENSUS TIGHTENING/IMPROVING TONIGHT THRU FRI WITH
REMNANTS OF ISAAC INTO THE MID MS VALLEY AND NEXT TROUGH ONTO THE
WEST COAST. CONSENSUS BETTER FRI NIGHT INTO SAT NIGHT...BUT
TIMING/PLACEMENT DIFFERENCES WITH WHATS LEFT OF ISAAC STILL ENOUGH
TO HAVE SENSIBLE WEATHER IMPACTS HEADING INTO THE WEEKEND. CHECK OF
OBS VS. MODEL DATA AT 18Z SHOWED ALL REASONABLE WITH THE LOCATION OF
ISAAC AND LOW/TROUGHING IN THE NORTHERN PLAINS INTO UPPER MIDWEST.
GFS REMAINED AS MUCH AS 10F TOO HIGH WITH SFC DEW POINTS OVER PARTS
OF MN/IA/WI AND DAKOTAS. PER WV IMAGERY...NAM APPEARED TOO FAR WEST
WITH THE MID LEVEL ISAAC CIRCULATION WHILE THE OTHER MODELS LOOKED
QUITE GOOD. REASONS TO FAVOR EACH MODEL BUT NO ONE CLEAR FAVORITE.
WITH THE TREND TOWARD A COMMON CONSENSUS...PREFERRED A MODEL/
ENSEMBLE BLEND. SHORT TERM FCST CONFIDENCE AVERAGE TO GOOD THIS
CYCLE.
IN THE SHORT TERM...QUIET TONIGHT WITH THE PRESSURE GRADIENT
CONTINUING TO TIGHTEN. SOUTH/SOUTHWEST WINDS REMAIN IN THE 10-20
MPH RANGE TONIGHT...KEEPING THE BOUNDARY LAYER MIXED AND LOWS WELL
ABOVE LATE AUG NORMALS. TIGHT GRADIENT REMAINS OVER THE AREA THU...
WITH 925MB WINDS IN THE 30KT RANGE AND SOUNDINGS SHOWING MIXING TO
AT LEAST 900MB. PLENTY OF DRY AIR IN THE SFC-850MB LAYER TO MIX/
ADVECT INTO THE AREA ON THE BRISK/STRONG SOUTHWEST LOW LEVEL FLOW.
THU DEW POINTS EXPECTED TO FALL INTO THE UPPER 40S TO MID 50S. THIS
ALONG WITH THE BRISK WINDS SETTING UP THE FIRE WEATHER CONCERNS.
SEE FIRE WEATHER SECTION BELOW FOR MORE DETAILS. MODELS QUITE
VARIABLE ON THE 925MB TEMPS/MOISTURE OVER THE AREA THU. WITH GFS
TOO COOL/WET WITH SFC-925MB TEMPS/DEW POINTS TODAY AND ITS KNOW WET
BIAS ON SFC DEW POINTS...ITS COOLER SOLUTION FOR THU DISCOUNTED.
PREVIOUS FCST FOR THU HAD HIGH TEMPS IN THE 95 TO 100F RANGE WELL
TRENDED BUT LOWERED DEW POINTS A BIT TO BETTER BLEND WITH NEIGHBORS
AND REFLECT TRENDS IN WESTERN IA TODAY. WITH THE LOWER DEW POINTS...
HEAT INDICES COME UP JUST SHORT OF ADVISORY CRITERIA. 15-25MPH AND
GUSTY WINDS ON THU WILL AID THE COMFORT LEVEL OF THE THU AIRMASS AS
WELL.
THE 925-850MB THERMAL RIDGE IS QUICKLY PUSHED SOUTH OF THE AREA THU
NIGHT/FRI AS A COLD FRONT DROPS SOUTH INTO AND ACROSS THE AREA. WITH
A DEEP...DRY AIRMASS AND LITTLE IN THE WAY OF SFC THRU MID LEVEL
FORCING FOR LIFT...LEFT THU NIGHT/FRI DRY. 925-850MB TEMPS DO
REMAIN WELL ABOVE NORMAL BEHIND THE FRONT...AND SOME QUESTION AS TO
HOW FAR SOUTH THE FRONT GETS ON FRI. FRI TO BE ANOTHER WARM DAY
WITH HIGH TEMPS STILL AROUND 90 OR LOWER 90S OVER THE CENTRAL/SOUTH
PARTS OF THE FCST AREA.
IMPROVING MODEL CONSENSUS KEEPS THE DEEPER 850-700MB MOISTURE AND
CIRCULATION FROM ISAAC SOUTH OF THE FCST AREA FRI NIGHT AND LEFT
THIS PERIOD DRY ACROSS THE FAR SOUTH END OF THE FCST AREA. 29.12Z
ECMWF/GFS/GEM MODEL CONSENSUS CLIPS THE SOUTHEAST END OF THE FCST
AREA WITH THE REMNANT CIRCULATION OF ISAAC AND THE 850-700MB
MOISTURE SAT/SAT NIGHT. STILL NOT A LOT OF CONFIDENCE WITH THIS
GIVEN MODELS ARE DEALING WITH A RATHER TIGHT/SMALL 850-500MB
CIRCULATION LIFTING NORTH THRU A MID LEVEL RIDGE AXIS. PLENTY OF
ROOM FOR ERROR HERE AND CHANGES IN LATER MODEL RUNS. THUS LEFT ANY
RAIN CHANCES ACROSS THE SOUTH END SAT/SAT NIGHT IN THE 20-30
PERCENT RANGE. WITH ANY PRECIP THESE PERIODS ON THE NORTH FRIDGE OF
THE REMNANT CIRCULATION AND MUCAPE TRENDING TO BE MINIMAL...REMOVED
TSRA MENTION FROM SAT/SAT NIGHT.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
309 PM CDT WED AUG 29 2012
29.00Z AND 29.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT SUN.
HOWEVER OVERALL TREND APPEARS BIT SLOWER/STRONGER THAN PREVIOUS RUNS
WITH REMNANTS OF ISAAC IN THE MID MS VALLEY AND STRONGER WITH
TROUGHING INTO SOUTH-CENTRAL CAN. REASONABLE CONSENSUS MON THRU WED
WITH BROAD LONGWAVE TROUGHING OVER CAN AND NORTHERN CONUS. HOWEVER
PLENTY OF DETAIL DIFFERENCES WITH THE STRONGER...TRACKABLE FEATURES
IN THIS FLOW. ECMWF DOES OFFER RATHER GOOD RUN-TO-RUN CONSISTENCY
WITH ITS 28.00Z RUN IN THE MON-WED PERIOD. LONG-TERM FCST CONFIDENCE
FOR RAIN CHANCES AVERAGE THIS CYCLE. CONFIDENCE FOR TEMPERATURES
CLOSER TO BUT STILL ABOVE SEASONAL NORMALS IN THE DAY 4-7 PERIOD
GOOD THIS CYCLE. LATEST MODEL CONSENSUS KEEPS REMNANTS OF ISAAC OVER
CENTRAL IL SUN MORNING...CLOSE ENOUGH FOR A SMALL -SHRA CHANCE OVER
THE SOUTHEAST END OF THE FCST AREA. CONSENSUS SHIFT OF THE MID LEVEL
FLOW PATTERN TO THE BROAD TROUGH OVER CAN/NORTH-CENTRAL CONUS FOR
MON-WED SENDS A SERIES OF FRONTS/TROUGHS ACROSS THE UPPER MIDWEST
FOR THE FIRST HALF OF NEXT WEEK. SOMEWHAT BETTER MODEL AGREEMENT FOR
ONE OF THESE TO PASS ON LABOR DAY /MON/...THEN WEAK HIGH PRESSURE
TUE AND ANOTHER STRONGER TROUGH/FRONT TO MOVE IN WED. BUT AGAIN
TIMING IS QUESTIONABLE MUCH BEYOND MON. RAIN CHANCES IN THE 20-40
PERCENT RANGE PER MODEL/ENSEMBLE CONSENSUS LOOK REASONABLE FOR MON
AND WED. GIVEN POTENTIAL FRONT/TROUGH TIMING ISSUES...MODEL/ENSEMBLE
CONSENSUS HIGHS/LOWS ABOUT 5F ABOVE NORMAL FOR MUCH OF DAYS 4-7
LOOKS GOOD.
&&
.AVIATION...TONIGHT AND THURSDAY
632 PM CDT WED AUG 29 2012
MAIN CONCERN IS ON LOW LEVEL WIND SHEAR POTENTIAL TONIGHT AT BOTH
TAF SITES. VFR CONDITIONS EXPECTED WITH MAINLY CLEAR SKIES THROUGH
THE TAF PERIOD. 925MB JET STRENGTHENS OVERNIGHT WITH BOTH THE NAM
AND RAP SHOWING 45 TO 50 KNOT WINDS ACROSS THE AREA. MAIN QUESTION
WILL BE HOW MUCH DECOUPLING WILL OCCUR AT THE SURFACE. FEEL BETTER
CHANCES ARE AT KLSE IN THE VALLEY AND THUS HAVE INCLUDED LLWS IN
THE 00Z TAF. AT KRST...SOME CONCERN WITH SURFACE WINDS STAYING UP
OR INCREASING THROUGH THE OVERNIGHT HOURS AS GRADIENT REMAINS
TIGHT. KRST LOOKS TO BE BORDERLINE TO HIT LLWS CRITERIA AND THUS
HAVE LEFT IT OUT FOR NOW AND WILL RE-EVAULATE FOR THE 06Z
ISSUANCE.
&&
.CLIMATE...THURSDAY
309 PM CDT WED AUG 29 2012
THURSDAY REMAINS ON TRACK TO BE THE HOTTEST DAY OF THE WEEK...AS THE
CORE OF THE HOT AIRMASS SPREADS ACROSS SOUTHEAST MINNESOTA AND
WESTERN WISCONSIN. WITH CURRENT RECORDS IN THE MIDDLE 90S AND
FORECAST HIGHS IN THE UPPER 90S TO NEAR 100...MANY AREAS SHOULD
COMFORTABLY ESTABLISH NEW RECORD HIGHS. BELOW ARE THE RECORD HIGH
INFORMATION FOR ROCHESTER AND LA CROSSE.
ROCHESTER MN
AUGUST 30...96/1941
AUGUST 31...93/1960
LA CROSSE WI
AUGUST 30...94/1969
AUGUST 31...95/1953
ALSO OF NOTE IS THE HISTORICAL RANKINGS FOR THE FREQUENCY OF 90
DEGREES AT LSE. THROUGH YESTERDAY AUG 28TH...LA CROSSE HAS SEEN 32
90 DEGREE DAYS AND THIS STANDS AT 10TH MOST OVERALL. IF THE CURRENT
FORECAST FOR AT LEAST 90 OR HIGHER TODAY THROUGH FRIDAY
VERIFIES...THIS WOULD PROPEL THE RANKING TO TIED FOR 3RD.
&&
.FIRE WEATHER...THURSDAY
309 PM CDT WED AUG 29 2012
AHEAD OF AN APPROACHING COLD FRONT...THE COMBINATION OF A HOT/DRY
AIRMASS AND STRONG SOUTHWESTERLY WINDS ARE LIKELY TO CREATE CRITICAL
FIRE WEATHER CONDITIONS THURSDAY ACROSS PARTS OF THE AREA. HIGH
TEMPERATURES ARE EXPECTED TO TOP OUT IN THE 95 TO 100 DEGREE RANGE
AND AFTERNOON RELATIVE HUMIDITIES WILL FALL TO BETWEEN 20 AND 30
PERCENT. A TIGHT PRESSURE GRADIENT WILL RESULT IN SUSTAINED
SOUTHWEST WINDS 15 TO 25 MPH WITH GUSTS UP TO 30 MPH POSSIBLE.
AS SUCH...THE FIRE WEATHER WATCH HAS BEEN UPGRADED TO A RED FLAG
WARNING FOR AREAS ACROSS SOUTHEAST MINNESOTA AND PARTS OF NORTHEAST
IOWA WHERE WINDS WILL BE A BIT STRONGER AND CONCERN IS FOR DRYING
CROPS AND FINE/GRASSY FUELS. ACROSS WESTERN INTO CENTRAL
WISCONSIN...PER COORDINATION WITH WISCONSIN DNR...CURRENT FUEL
MOISTURE LEVELS SUGGEST RED FLAG WARNING IS NOT WARRANTED BUT
CONDITIONS REMAINS CRITICAL.
THE COLD FRONT WILL SAG ACROSS MINNESOTA AND WISCONSIN LATE
THURSDAY...AND WINDS WILL SLACKEN ALONG WITH RECOVERING RELATIVE
HUMIDITIES. ON FRIDAY...WITH THE FRONTAL BOUNDARY LINGERING
AROUND...IMPROVING CONDITIONS WILL BE SEEN HOWEVER HIGHS ARE
EXPECTED TO STILL BE ABOVE NORMAL IN THE UPPER 80S TO LOWER 90S.
PLEASE SEE MKERWFARX AND MKEFWFARX FOR DETAILS CONCERNING THE FIRE
WEATHER FORECAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
309 PM CDT WED AUG 29 2012
WI...NONE.
MN...RED FLAG WARNING FROM NOON TO 8 PM CDT THURSDAY FOR MNZ079-
086>088-094>096.
IA...RED FLAG WARNING FROM NOON TO 8 PM CDT THURSDAY FOR IAZ008-
009-018.
&&
$$
SHORT TERM.....RRS
LONG TERM......RRS
AVIATION...RABERDING
CLIMATE........ZT
FIRE WEATHER...ZT