Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/01/12
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1014 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 03Z...
* TIMING OF PRECIP ARRIVAL SAT AS TROPICAL REMNANTS STEADILY
APPROACH FROM THE SOUTH...WITH PSBL LOW END VFR CIGS SAT NGT.
BEACHLER
//DISCUSSION...UPDATED 00Z...
EXPANSIVE AREA OF CLOUDS COVER ALL OF THE AREA...AS TROPICAL
REMNANTS CONTINUE TO FEED NORTH. THE SFC LOW PRESSURE REMAINS
CENTERED WELL SW OF THE AREA IN SOUTHWEST MO. THE BEST MOISTURE
REMAINS ACROSS MO AND PORTIONS OF SOUTHWEST IL...SLOWLY LIFTING
NORTH. CIGS THRU THIS EVE WILL STEADILY LOWER...HOWEVER REMAIN
VFR CONDS. GUIDANCE HAS CONTINUED TO SUGGEST THAT VCSH MAY
OVERSPREAD AIRFIELDS AFT DAYBREAK...THEN AS ADDTL MOISTURE LIFTS
NORTH ACROSS THE AREA SHOWER COVERAGE WILL GROW. WHILE IT IS
POSSIBLE A FEW RUMBLES OF THUNDER MAY OCCUR...HAVE OPTED TO LEAVE
MENTION OF THUNDER OUT OF THE CURRENT TAF DUE TO THE UNCERTAINTY.
AS MENTIONED EARLIER ABOUT CIGS LOWERING...FEEL THAT OVERALL CIGS
WILL REMAIN VFR. A FEW POINTS COULD LOWER TOWARDS THE LATE SAT
AFTN TIMEFRAME INTO HIGH END MVFR CIGS...ALTHOUGH THIS TO IS A LOW
CONFIDENCE. THEN EXPECT STEADY TO AT TIMES MODERATE RAINFALL SAT
NGT THRU EARLY SUN AS THE TROPICAL REMNANTS WILL BE MAINLY
OVERHEAD OF CENTRAL IL. WITH ALL OF THIS BEING SAID...HIGH
PRESSURE WELL NORTH OF THE REGION COULD PLAY A LARGER ROLE IN
ERODING LLVL MOISTURE. THIS TOO COULD LIMIT LLVL CLOUDS AS WELL AS
PRECIP COVERAGE WITH A STEADY DRY NORTHEAST/EAST FLOW.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* HIGH CONFIDENCE IN CIGS FORECAST THRU 15Z SAT.
* MEDIUM CONFIDENCE IN CIGS SAT AFTN.
* HIGH CONFIDENCE IN PRECIP DEVELOPING SAT MIDDAY/AFTN AND
CONTINUES THRU SAT NGT.
* LOW CONFIDENCE ON TIMING OF PRECIP.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...OCCASIONAL RA. MVFR PSBL IFR CIGS.
MONDAY...CHC RA ISO TSRA. MVFR PSBL.
TUESDAY THROUGH WEDNESDAY...VFR. CHC SHRA/ISO TSRA W/MVFR CIGS.
THURSDAY...VFR.
BEACHLER
&&
.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
658 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 00Z...
* WINDS SHIFTING NE AT 00Z.
* TIMING OF PRECIP ARRIVAL SAT AS TROPICAL REMNANTS STEADILY
APPROACH FROM THE SOUTH...WITH PSBL LOW END VFR CIGS SAT NGT.
BEACHLER
//DISCUSSION...UPDATED 00Z...
EXPANSIVE AREA OF CLOUDS COVER ALL OF THE AREA...AS TROPICAL
REMNANTS CONTINUE TO FEED NORTH. THE SFC LOW PRESSURE REMAINS
CENTERED WELL SW OF THE AREA IN SOUTHWEST MO. THE BEST MOISTURE
REMAINS ACROSS MO AND PORTIONS OF SOUTHWEST IL...SLOWLY LIFTING
NORTH. CIGS THRU THIS EVE WILL STEADILY LOWER...HOWEVER REMAIN
VFR CONDS. GUIDANCE HAS CONTINUED TO SUGGEST THAT VCSH MAY
OVERSPREAD AIRFIELDS AFT DAYBREAK...THEN AS ADDTL MOISTURE LIFTS
NORTH ACROSS THE AREA SHOWER COVERAGE WILL GROW. WHILE IT IS
POSSIBLE A FEW RUMBLES OF THUNDER MAY OCCUR...HAVE OPTED TO LEAVE
MENTION OF THUNDER OUT OF THE CURRENT TAF DUE TO THE UNCERTAINTY.
AS MENTIONED EARLIER ABOUT CIGS LOWERING...FEEL THAT OVERALL CIGS
WILL REMAIN VFR. A FEW POINTS COULD LOWER TOWARDS THE LATE SAT
AFTN TIMEFRAME INTO HIGH END MVFR CIGS...ALTHOUGH THIS TO IS A LOW
CONFIDENCE. THEN EXPECT STEADY TO AT TIMES MODERATE RAINFALL SAT
NGT THRU EARLY SUN AS THE TROPICAL REMNANTS WILL BE MAINLY
OVERHEAD OF CENTRAL IL. WITH ALL OF THIS BEING SAID...HIGH
PRESSURE WELL NORTH OF THE REGION COULD PLAY A LARGER ROLE IN
ERODING LLVL MOISTURE. THIS TOO COULD LIMIT LLVL CLOUDS AS WELL AS
PRECIP COVERAGE WITH A STEADY DRY NORTHEAST/EAST FLOW.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN WIND DIR/SPEED.
* HIGH CONFIDENCE IN CIGS FORECAST THRU 15Z SAT.
* MEDIUM CONFIDENCE IN CIGS SAT AFTN.
* HIGH CONFIDENCE IN PRECIP DEVELOPING SAT MIDDAY/AFTN AND
CONTINUES THRU SAT NGT.
* LOW CONFIDENCE ON TIMING OF PRECIP.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...OCCASIONAL RA. MVFR PSBL IFR CIGS.
MONDAY...CHC RA ISO TSRA. MVFR PSBL.
TUESDAY THROUGH WEDNESDAY...VFR. CHC SHRA/ISO TSRA W/MVFR CIGS.
THURSDAY...VFR.
BEACHLER
&&
.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 MARQUETTE MI
751 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 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 750 PM EDT FRI AUG 31 2012
VFR CONDITIONS ARE EXPECTED AS DRY HIGH PRESSURE REMAINS IN CONTROL THROUGH
MUCH OF THE WEEKEND.
&&
.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...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GLASGOW MT
757 PM MDT FRI AUG 31 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
UPDATE...MINOR UPDATE TO POPS/SKY/TEMPS TONIGHT. INCREASED
MOISTURE IN THE WATER VAPOR IMAGE WILL LEAD TO A SLIGHTLY WARMER
NIGHT FOR NORTHEAST MONTANA. REGIONAL RADAR SHOWS AN INCREASE IN
THUNDER... NOT SO MUCH FOR RAIN ACROSS REGIONS SOUTH AND WEST.
LATEST HRRR RUN DOES BRING CONVECTION INTO THE CWA SOUTH OF THE
RIVER LATE THIS EVENING...THEREFORE BUMPED POPS UP. PROTON
A BROAD UPPER LEVEL RIDGE OVER CENTRAL PLAINS AND A CLOSED UPPER
LOW SPINNING OVER SOUTHERN BRITISH COLUMBIA. THIS WILL KEEP
EASTERN MONTANA UNDER SOUTHWESTERLY FLOW ALOFT TROUGH SUNDAY. A
DEVELOPING LEE SIDE SURFACE TROUGH WILL SET UP A BREEZY
SOUTHEASTERLY FLOW WITH THE STRONGEST WINDS ALONG THE NORTH DAKOTA
BORDER.
THERMAL RIDGING WILL KEEP THE TEMPERATURES 10F TO 15F DEGREES
ABOVE NORMAL TODAY THROUGH SATURDAY. THIS WILL CREATING LEE TO LOW
AND LOW RELATIVE HUMIDITY DURING THE AFTERNOON TODAY AND ON
SATURDAY WITH POOR RELATIVE HUMIDITY RECOVERY OVERNIGHT. EXPECT
SOME WEAK INSTABILITY THIS AFTERNOON THROUGH SATURDAY EVENING
AHEAD OF A COLD FRONT WHICH WILL MOVE THROUGH THE AREA SATURDAY
EVENING. THE RESULT WILL ISOLATED THUNDERSTORMS WHICH WILL PRODUCE
CLOUD TO GROUND LIGHTNING STRIKES. THE SPC CONVECTIVE OUTLOOK
INCLUDES EASTERN MONTANA WITHIN THE AREA FOR GENERAL
THUNDERSTORMS.
MONSOONAL MOISTURE CONTINUES FLOWING NORTHEAST INTO EASTERN
MONTANA IN THE MID AND UPPER LEVEL BUT THE SURFACE SHOULD REMAIN
DRY. THE ISOLATED THUNDERSTORMS THAT DEVELOP FROM THIS AFTERNOON
THROUGH SATURDAY EVENING WILL BE FAIRLY DRY PRODUCING VERY LITTLE
IN THE WAY OF RAINFALL. SO DECIDED TO EXTEND THE RED FLAG WARNING
THOUGH SUNDAY MORNING FOR ALL OF OUR CWA.
TONIGHT AND SATURDAY THE CANADIAN LOW BEGINS ITS TREK EAST ALONG
THE INTERNATIONAL BORDER AND THIS WILL COLLECT THE LEE SIDE TROUGH
AND PUSH IT ACROSS EASTERN MONTANA AS A COLD FRONT. THE LOW
PRESSURE SYSTEM WILL BECOME STACKED OVER EASTERN ALBERTA BY
SATURDAY EVENING. THE SURFACE FRONT WILL CROSS THE REGION ON
SATURDAY AFTERNOON SHIFTING THE WINDS TO THE WEST.
SATURDAY NIGHT AROUND MIDNIGHT THE CAA WILL ARRIVE BEHIND THE 850
MB FRONT WHICH WILL BRING ABOUT A WIND SHIFT TO THE NORTHWEST.
EXPECT WINDS 15 TO 25 MPH WITH OCCASIONAL GUSTS UP TO 40 MPH
BEHIND THIS FRONT. THE WINDS SHOULD START TO DROP OFF SUNDAY
AFTERNOON INTO SUNDAY EVENING. ALTHOUGH COOLER AIR WILL FLOW IN
BEHIND THE FRONT IT WILL CONTINUE TO BE DRY AIR FOR CONTINUED FIRE
WEATHER CONCERNS. DECIDED NOT TO ISSUE A LAKE WIND ADVISORY FOR
SATURDAY EVENING THROUGH SUNDAY AT THIS POINT BUT IT LOOKS LIKE
ONE WILL BE NEEDED FOR FORT PECK LAKE. RSMITH
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
SYNOPTIC SET UP... A LARGE HEAT DOME EXISTS ACROSS THE LOWER HALF
OF THE GREAT BASIN UP TO ABOUT THE UTAH/IDAHO BORDER FOR THE
WESTERN HALF OF THE US. TO THE NORTH A COLD CORE TROUGH HAS
DROPPED DOWN INTO BRITISH COLUMBIA... ALBERTA... AND SASKATCHEWAN.
SANDWICHED IN BETWEEN... THE PACIFIC NORTHWEST THROUGH THE
NORTHERN US PLAINS INCLUDING NEMONT REMAINS IN ZONAL FLOW.
SUNDAY NIGHT THROUGH TUESDAY NIGHT... LAST COUPLE WARM PERIODS CAN
BE ANTICIPATED SUNDAY NIGHT AND MONDAY WITH ZONAL FLOW IN PLACE
ACROSS THE REGION. AFTERWARD THE TROUGH TO THE NORTH BEGINS TO
PRESS DOWN INTO EASTERN MONTANA AND GAIN DOMINANCE OVER THE
FORECAST. TEMPERATURES SHOULD RAPIDLY DROP OFF BEHIND A FRONT
MONDAY NIGHT WITH HIGHS IN THE 60S AND 70S BY TUESDAY. BARING THE
PASSAGE OF THE COLD FRONT MOST OF THESE PERIODS SHOULD REMAIN DRY.
WEDNESDAY ONWARD... WITH THE BULK OF THE COLD CORE TROUGH MOVING
THROUGH THE NORTHERN PLAINS AND INTO THE UPPER MISSISSIPPI
VALLEY... THE HEAT DOME ACROSS THE SOUTHWEST WILL SURGE UP THE
WEST COAST EXTENDING A RIDGE INTO BRITISH COLUMBIA AND PLACING
EASTERN MONTANA IN NORTHWEST FLOW. WHILE INITIALLY COLD STARTING
OFF... BY FRIDAY THIS RIDGE WILL GAIN HEAT INTENSITY AND BEGIN
MIGRATING EASTWARD RAISING HIGHS BACK INTO THE LOWER 80S. CONDITIONS
SHOULD BE DRY UNLESS AN ISOLATED AFTERNOON INSTABILITY SHOWER
BEGINS TO SHOW UP ON THE NORTHWEST FLOW TOWARD THE END. GAH
PREVIOUS LONG TERM DISCUSSION...
GFS HAS COME INTO BETTER ALIGNMENT WITH THE GEM/ECMWF WITH
DEVELOPING A BROAD TROUGH ACROSS CENTRAL CANADA FOR THE UPCOMING
WEEK. WITH RIDGE KEPT OFF THE WEST COAST...COOLER NORTHWEST FLOW
WILL DOMINATE THE WEATHER PATTERN FOR NORTHEAST MONTANA.
FIRST OF THE CLIPPER TYPE SHORTWAVE/UPPER LOW TRACKS ACROSS THE
PRAIRIE PROVINCES SUNDAY NIGHT INTO MONDAY...PULLING COOLER HIGH
PRESSURE ACROSS THE NORTHERN PLAINS. NEXT SHORTWAVE/LOW FOLLOWS
CLOSE BEHIND WITH ANOTHER COLD FRONT PASSAGE EXPECTED ON TUESDAY.
FRONT CURRENTLY EXPECTED TO BE DRY AS MOISTURE LIMITED WITH THE
WAVE COMING OUT OF THE NORTH. ANOTHER 5 TO 10 DEGREE DROP IN
TEMPERATURES IS EXPECTED BEHIND THIS WAVE FOR MIDWEEK.
TEMPERATURES EXPECTED TO REBOUND SLIGHTLY INTO THE END OF THE WEEK
WITH RIDGE BUILDING INTO THE NORTHERN ROCKIES. MODELS BEGINNING TO
HINT AT SOME SORT OF CUT OFF LOW DEVELOPING OVER THE PACIFIC
NORTHWEST...WITH THE ECMWF STRONGEST WITH THIS FEATURE. THIS COULD
LIMIT THE PULL OF WARM AIR NORTHWARD AND KEEP TEMPERATURES MUCH
CLOSER TO NORMAL VALUES. EBERT
&&
.AVIATION...
VFR...WITH SOME MVFR VISIBILITIES POSSIBLE DUE TO HAZE/SMOKE.
HAZE/SMOKE FROM WILDFIRES ACROSS WESTERN MONTANA HAVE MIXED DOWN
TO THE SURFACE AND CAUSED VISIBILITY OBSCURATION EARLY THIS
EVENING AT KGGW AND KOLF. THIS SMOKE/HAZE IS NOT EXPECTED TO EXIT
THE AREA UNTIL A COLD FRONT PASSAGE LATE TONIGHT OR SATURDAY.
HIGH BASED THUNDERSTORMS ARE POSSIBLE ACROSS THE REGION TONIGHT
THROUGH TOMORROW AND COULD PRODUCE STRONG ERRATIC WIND GUSTS.
WINDS WILL BE OUT OF THE SOUTHEAST TONIGHT AROUND 10 TO 20 KTS...
THEN DROPPING TO AROUND 10 KTS DURING THE LATE MORNING AND SWITCHING
TO THE WEST BEHIND A COLD FRONT. GAH/SCT
&&
.FIRE WEATHER...
WE ARE LOOKING AT POSSIBLE CRITICAL FIRE WEATHER CONDITIONS TODAY
THROUGH SUNDAY. EXPECT WARMING TEMPERATURES WITH HIGHS IN THE MID
90S AND RELATIVE HUMIDITIES RANGING BETWEEN 15 TO 20 PERCENT IN
WESTERN ZONES AND 20 TO 25 PERCENT IN THE EASTERN FIRE ZONES 120
AND 122. SOUTHEAST WINDS OF 15 TO 25 MPH WILL HAPPEN ACROSS MOST
OF THE FIRE ZONES WITH THE STRONGER WINDS LOCATED ALONG THE MONTANA
NORTH DAKOTA BORDER.
THIS AFTERNOON THROUGH SATURDAY NIGHT CONDITIONS BECOME UNSTABLE
AND THE DEVELOPMENT OF ISOLATED THUNDERSTORMS IS POSSIBLE. THESE
THUNDERSTORMS WILL BECOME GOOD LIGHTNING PRODUCERS ACROSS EASTERN
MONTANA. A COLD FRONT WILL MOVE ACROSS THE REGION SATURDAY EVENING
WITH THE WINDS SHIFTING TO THE WEST NORTHWEST. EXPECT SUSTAINED
WIND SPEEDS OF 20 MPH BEHIND THE FRONT WITH GUSTS UP TO 30 MPH
POSSIBLE INTO SUNDAY AFTERNOON. ANY FIRES STARTED BY LIGHTNING
WILL BE IMPACTED BY THIS SUDDEN SHIFT AND CHANGE IN WIND SPEED AND
STRENGTH. RSMITH
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT SUNDAY FOR MTZ120-122-134>137.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
847 PM CDT FRI AUG 31 2012
.DISCUSSION...
SOME MINOR TWEAKS TO WINDS AND CLOUD COVER FOR THE EVENING UPDATE
TONIGHT...AND PUT OFF CHANCES FOR MEASURABLE PRECIP TOWARDS THE
EARLY MORNING HOURS. RADAR CONTINUES TO SHOW LIGHT ECHOS MOVING
INTO EASTERN ND AND DISSIPATING...BUT THERE HAVE BEEN NO REPORTS
OF ANYTHING REACHING THE GROUND...AND WITH DEW POINTS STILL IN THE
40S THE ECHOES SEEM MID LEVEL WITH NOT EVEN SPRINKLES REACHING THE
GROUND. THE HRRR AND RAP HAVE SOME PRECIP GETTING INTO THE
NORTHWESTERN COUNTIES AFTER 08Z OR SO...ALTHOUGH THE NAM IS STILL
DRY. WILL CONTINUE TO KEEP 20 POPS FOR THAT AREA TOWARDS MORNING
AS A WEAK SHORTWAVE COME OUT. INCREASED CLOUD COVER SOMEWHAT
OVERNIGHT AS HIGH AND MID CLOUDS CONTINUE TO MOVE IN. KEPT LOWS IN
THE UPPER 50S TO LOW 60S AS TEMPS SEEM ON TRACK.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE AS WINDS WILL BE THE PRIMARY CONCERN.
LIGHT SOUTHEASTERLY WINDS OVERNIGHT WILL INCREASE BY MID MORNING
TOMORROW. SUSTAINED FLOW AT 15 TO 20 KTS WITH GUST UP ABOVE 25 KTS
ARE POSSIBLE.
&&
.PREV DISCUSSION... /ISSUED 229 PM CDT FRI AUG 31 2012/
SHORT TERM.../TONIGHT THROUGH MON/
FORECAST CHALLENGE FOR THE SHORT TERM WILL BE CONVECTIVE POTENTIAL
LATE EVENING TONIGHT...WINDS ON SATURDAY...AND THEN
PLACEMENT/TIMING OF NEXT COLD FRONT PROGGED TO MOVE THROUGH SAT
NIGHT INTO SUNDAY. PREFER BLEND OF NAM AND ECMWF MODEL SOLUTIONS
DUE TO BETTER AGREEMENT BETWEEN THE TWO MODELS AND CONTINUITY. GFS
BRINGING A VORT MAX OUT OF NORTHERN UTAH AND INTO CNTRL ND TO
GENERATE SOME PRECIP IN THE 06Z TO 12Z TIMEFRAME...WHEREAS THE
NAM/ECMWF ARE DRY.
TONIGHT...CURRENT RADAR CONTINUES TO SHOW ELEVATED TCU OVER CNTRL
ND MOVING INTO SHEYENNE BASIN. STILL SEEING LITTLE AS FAR AS
GROUND TRUTH FOR CIGS BLO 100K...SO EXPECT VIRGA. HOWEVER...AM
SEEING SOME HIGHER REFLECTIVITIES OVER THE LAST HOUR SO WILL
INTRODUCE SPRINKLES IN THE FAR EAST. AN ISOLD TSTM WOULD ALSO BE
POSSIBLE BUT CONFIDENCE IS LOW. TIMING OF PRECIP AFT 06Z TONIGHT
WILL BE FIRST CHALLENGE. GFS DOES EXTEND POPS INTO FAR WEST IN THE
06Z TO 12Z TIMEFRAME. DECENT WAA OVERNIGHT TONIGHT WILL PROVIDE
POTENTIAL FOR ELEVATED ACTIVITY BUT UPPER PERTURBATION IS STRONGER
ON GFS THAN ECMWF/NAM...WHICH ARE DRIER AND GENERALLY PLACE
PRECIP IN THIS TIMEFRAME FURTHER TO THE NORTHWEST. AT CURRENT TIME
WILL KEEP INHERITED LOW POPS BUT CONFIDENCE IS LOW.
SATURDAY...AS LOW PRESSURE DEVELOPS OVER MT AND COLD FRONT BEGINS
TO MOVE EAST...TIGHTENING GRADIENT AND AN ADIABATIC LAYER UP TO
H875 LEVEL WILL GENERATE GUSTY WINDS BY LATE MORNING. MIXED LAYER
SHOWING AROUND 35 KTS AVAILABLE TO MIX TO SURFACE...THUS WILL
ISSUE A SPECIAL WEATHER STATEMENT FOR THE DEVILS LAKE AREA FOR
BOATERS PLANNING OUTDOOR ACTIVITIES THIS HOLIDAY WEEKEND. WIND
ADVISORY CONDS MAY BE MET BUT WILL LET LATER SHIFTS VIEW 00Z
MODELS AND MAKE THE CALL. TEMPS EXPECTED TO RISE INTO UPPER 80S OR
PERHAPS TAP INTO THE 90S IN THE FAR WEST.
SATURDAY NIGHT AND SUNDAY...COLD FRONT APPROACHES FROM WESTERN
DAKOTAS. DEWPOINTS AHEAD OF FRONT GENERALLY IN THE MID 60S SUN
AFTN. ALTHOUGH SHOWALTERS ARE NEG ACROSS AREA SAT NIGHT...BOUNDARY
WILL NOT MOVE INTO VALLEY UNTIL LATE SUN AFTN OR EARLY EVENING...AND
WITH PEAK HEATING SHOWALTERS DROP TO AROUND NEG 7 IN SERN ZONES BY
LATE AFTN. THUS THINK THE BEST CHANCE FOR TSTM ACTIVITY WILL BE
ON MN SIDE OF CWA WITH STRONGEST STORMS IN THE SOUTHEAST.
SUN NIGHT INTO MONDAY...COLD FRONT MOVES THROUGH BY EARLY MON
MORNING AND HAVE PULLED POPS AFT 06Z. HIGH PRESSURE THEN SETS IN
FOR MONDAY...WITH DAYTIME HIGHS IN THE MID 80S
LONG TERM...
SEVERAL HARD TO TIME SHORTWAVES WILL MOVE THROUGH THE REGION WITH NW
FLOW ALOFT. TEMPS SHOULD COOL BELOW NORMAL BY MIDWEEK WITH COOL
850MB TEMPS FALLING TO BELOW +10C FOR THE FIRST TIME IN A WHILE.
THERE WILL BE LOW POPS FOR CONVECTION THROUGH THE PERIOD...ALTHOUGH
THE BEST CHANCES APPEAR TO BE TUE NIGHT AND WED WITH THE STRONGEST
WAVE...WITH ANOTHER SHORTWAVE FOR THU/THU NIGHT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1050 PM CDT FRI AUG 31 2012
.DISCUSSION...
THE CENTER OF TROPICAL DEPRESSION ISAAC IS OVER SOUTHWEST MISSOURI
TRACKING TO THE NORTH. THE OUTER SCATTERED CONVECTION TO THE
SOUTHEAST HAS DISSIPATED DUE TO THE LOSS OF DAYTIME HEATING BUT
THE MORE CONCENTRATED RAIN BANDS CONTINUE INTO THE NIGHT CLOSER TO
THE CENTER. ONE PARTICULAR BAND OF SHOWERS AND THUNDERSTORMS EXTENDS
ALONG THE MIDDLE MISSISSIPPI RIVER VALLEY INTO ARKANSAS. EXPECT
THIS BAND OF SHOWERS TO CONTINUE AFFECTING THE NORTHWEST PART OF
THE FORECAST AREA FOR THE NEXT SEVERAL HOURS.
THE RISK FOR SEVERE WEATHER HAS ENDED TONIGHT DUE TO THE LOSS OF
DAYTIME HEATING BUT MORE STRONG STORMS ARE POSSIBLE DURING THE
DAY SATURDAY AND SUNDAY. THE ONLY POTENTIAL RISK TONIGHT MIGHT BE
PROBLEMS FROM HEAVY RAIN IN NORTHEAST ARKANSAS BUT THAT CHANCE
APPEARS TO BE LOW RIGHT NOW. SOUTHERLY WINDS WILL AVERAGE IN THE
10 TO 20 MPH RANGE THROUGH THE NIGHT.
SWC
&&
.PREV DISCUSSION... /ISSUED 353 PM CDT FRI AUG 31 2012/
DISCUSSION...20Z SURFACE ANALYSIS PLACES THE REMNANTS OF TROPICAL
DEPRESSION ISAAC ACROSS SOUTHWEST MISSOURI WITH SHOWER AND
THUNDERSTORM ACTIVITY CONFINED PREDOMINANTLY TO THE MISSISSIPPI
RIVER DELTA AND NORTHEAST MISSISSIPPI. TEMPERATURES AS OF 3 PM CDT
RANGE FROM THE 80S ACROSS EASTERN ARKANSAS WHERE CLOUD COVER HAS
PERSISTED THROUGHOUT THE DAY AND UPPER 80S TO LOWER 80S ACROSS THE
REMAINDER OF THE MID SOUTH WHERE CLOUD COVER HAS MIXED OUT TODAY.
WIND ADVISORY CONCERNS ALONG WITH THE POTENTIAL FOR STRONG TO
PERHAPS SEVERE THUNDERSTORMS INTO THIS EVENING ARE THE MAIN
CONCERNS IN THIS AFTERNOON/S FORECAST ISSUANCE.
SHORT TERM...(TONIGHT THROUGH MONDAY)...THE REMNANTS OF TROPICAL
DEPRESSION ISAAC ACROSS SOUTHWEST MISSOURI ALONG WITH DAYTIME
INSTABILITY PRODUCED BY SOME SUNSHINE TODAY HAVE PRODUCED
FAVORABLE CONDITIONS FOR MINI-SUPERCELL TYPE STORMS TO DEVELOP
MAINLY ACROSS EAST ARKANSAS AND THE MISSOURI BOOTHEEL. MODERATELY
STEEP LOW LEVEL LAPSE RATES AROUND 6.5 C/KM...0-1 STORM RELATIVE
HELICITY VALUES BETWEEN 200-250 M2/S2...SURFACE BASED CAPE VALUES
BETWEEN 500-1000 J/KG...SUPPORT THE CONTINUED DEVELOPMENT OF LOW
TOPPED MINI-SUPERCELLULAR TYPE STORMS CAPABLE OF PRODUCING BRIEF
SHORT-LIVED TORNADOES. THINK THIS THREAT WILL BEGIN TO DIMINISH
AFTER SUNSET AS THE BEST SHEAR LIFTS NORTH OF THE MID SOUTH.
LATEST WATER VAPOR SATELLITE/WSR-88D VAD WIND PROFILERS INDICATE
925 MB WINDS BETWEEN 25-35 KTS ACROSS THE MISSISSIPPI RIVER DELTA.
THUS...DECIDED TO EXTEND THE CURRENT WIND ADVISORY UNTIL 6 PM THIS
EVENING.
SHORT TERM MODELS INDICATE THE REMNANTS OF ISAAC WILL CONTINUE TO
MOVE EAST ACROSS CENTRAL MISSOURI ALONG THE I-70 CORRIDOR THROUGH
SUNDAY AND INTO THE OHIO VALLEY BY MONDAY. THIS WILL RESULT IN THE
CONTINUED POTENTIAL FOR SHOWERS AND THUNDERSTORMS EACH
DAY...ESPECIALLY DURING THE DAY WITH MAXIMUM HEATING AND
INSTABILITY. A FEW STRONG THUNDERSTORMS WILL REMAIN POSSIBLE
DURING THIS PERIOD WITH GUSTY WINDS POSSIBLE.
LONG TERM...(TUESDAY THROUGH FRIDAY)...12Z LONG TERM MODELS
INDICATE A COLD FRONT WILL MOVE THROUGH THE MID SOUTH NEXT
WEDNESDAY NIGHT AND THURSDAY AS AN UPPER LEVEL TROUGH MOVES INTO
THE EASTERN UNITED STATES. THUS...KEPT SLIGHT CHANCE/POPS IN THE
FORECAST UNTIL THE FRONT PASSES THROUGH. HIGH PRESSURE WILL RETURN
FOR THE REMAINDER OF THE LONG TERM FORECAST.
CJC
&&
.AVIATION...
00Z TAFS
PRIMARY FORECAST CONCERN IS CONVECTIVE LINE LIFTING NORTHEAST
THROUGH EASTERN AR. THIS LINE REPRESENTS THE FIRST REAL CHANCE OF
TS AT MEM FOR THE DAY. THIS LINE IS RATHER STRONGLY FORCED... BUT
WILL BE ENCOUNTERING A GRADUALLY STABILIZING LOWER ATMOSPHERE BY THE
TIME IT APPROACHES THE MS RIVER. HRRR MODEL SHOWS THIS LINE WEAKENING
OVER TIME AND HAVE PLACED A PREDOMINATE SHRA WITH VCTS IN FOR MEM.
TIME OF ARRIVAL TOOL PLACES THIS LINE NEAR MEM AT 0215Z.
OTHER THAN A MVFR VSBY IN CONVECTIVE SHOWERS...VFR SHOULD PREVAIL
THROUGH THE EVENING. NAM LOW LEVEL MOISTURE PROGS SUGGEST A SLIGHT
CHANCE OF MVFR CIGS TOWARD SUNRISE...WITH BETTER CHANCES FOR MVFR
CIGS AT TUP.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS MEMPHIS TN
646 PM CDT FRI AUG 31 2012
.UPDATE...
UPDATED FOR AVIATION.
&&
.PREV DISCUSSION... /ISSUED 353 PM CDT FRI AUG 31 2012/
DISCUSSION...20Z SURFACE ANALYSIS PLACES THE REMNANTS OF TROPICAL
DEPRESSION ISAAC ACROSS SOUTHWEST MISSOURI WITH SHOWER AND
THUNDERSTORM ACTIVITY CONFINED PREDOMINANTLY TO THE MISSISSIPPI
RIVER DELTA AND NORTHEAST MISSISSIPPI. TEMPERATURES AS OF 3 PM CDT
RANGE FROM THE 80S ACROSS EASTERN ARKANSAS WHERE CLOUD COVER HAS
PERSISTED THROUGHOUT THE DAY AND UPPER 80S TO LOWER 80S ACROSS THE
REMAINDER OF THE MID SOUTH WHERE CLOUD COVER HAS MIXED OUT TODAY.
WIND ADVISORY CONCERNS ALONG WITH THE POTENTIAL FOR STRONG TO
PERHAPS SEVERE THUNDERSTORMS INTO THIS EVENING ARE THE MAIN
CONCERNS IN THIS AFTERNOON/S FORECAST ISSUANCE.
SHORT TERM...(TONIGHT THROUGH MONDAY)...THE REMNANTS OF TROPICAL
DEPRESSION ISAAC ACROSS SOUTHWEST MISSOURI ALONG WITH DAYTIME
INSTABILITY PRODUCED BY SOME SUNSHINE TODAY HAVE PRODUCED
FAVORABLE CONDITIONS FOR MINI-SUPERCELL TYPE STORMS TO DEVELOP
MAINLY ACROSS EAST ARKANSAS AND THE MISSOURI BOOTHEEL. MODERATELY
STEEP LOW LEVEL LAPSE RATES AROUND 6.5 C/KM...0-1 STORM RELATIVE
HELICITY VALUES BETWEEN 200-250 M2/S2...SURFACE BASED CAPE VALUES
BETWEEN 500-1000 J/KG...SUPPORT THE CONTINUED DEVELOPMENT OF LOW
TOPPED MINI-SUPERCELLULAR TYPE STORMS CAPABLE OF PRODUCING BRIEF
SHORT-LIVED TORNADOES. THINK THIS THREAT WILL BEGIN TO DIMINISH
AFTER SUNSET AS THE BEST SHEAR LIFTS NORTH OF THE MID SOUTH.
LATEST WATER VAPOR SATELLITE/WSR-88D VAD WIND PROFILERS INDICATE
925 MB WINDS BETWEEN 25-35 KTS ACROSS THE MISSISSIPPI RIVER DELTA.
THUS...DECIDED TO EXTEND THE CURRENT WIND ADVISORY UNTIL 6 PM THIS
EVENING.
SHORT TERM MODELS INDICATE THE REMNANTS OF ISAAC WILL CONTINUE TO
MOVE EAST ACROSS CENTRAL MISSOURI ALONG THE I-70 CORRIDOR THROUGH
SUNDAY AND INTO THE OHIO VALLEY BY MONDAY. THIS WILL RESULT IN THE
CONTINUED POTENTIAL FOR SHOWERS AND THUNDERSTORMS EACH
DAY...ESPECIALLY DURING THE DAY WITH MAXIMUM HEATING AND
INSTABILITY. A FEW STRONG THUNDERSTORMS WILL REMAIN POSSIBLE
DURING THIS PERIOD WITH GUSTY WINDS POSSIBLE.
LONG TERM...(TUESDAY THROUGH FRIDAY)...12Z LONG TERM MODELS
INDICATE A COLD FRONT WILL MOVE THROUGH THE MID SOUTH NEXT
WEDNESDAY NIGHT AND THURSDAY AS AN UPPER LEVEL TROUGH MOVES INTO
THE EASTERN UNITED STATES. THUS...KEPT SLIGHT CHANCE/POPS IN THE
FORECAST UNTIL THE FRONT PASSES THROUGH. HIGH PRESSURE WILL RETURN
FOR THE REMAINDER OF THE LONG TERM FORECAST.
CJC
&&
.AVIATION...
00Z TAFS
PRIMARY FORECAST CONCERN IS CONVECTIVE LINE LIFTING NORTHEAST
THROUGH EASTERN AR. THIS LINE REPRESENTS THE FIRST REAL CHANCE OF
TS AT MEM FOR THE DAY. THIS LINE IS RATHER STRONGLY FORCED... BUT
WILL BE ENCOUNTERING A GRADUALLY STABILIZING LOWER ATMOSPHERE BY THE
TIME IT APPROACHES THE MS RIVER. HRRR MODEL SHOWS THIS LINE WEAKENING
OVER TIME AND HAVE PLACED A PREDOMINATE SHRA WITH VCTS IN FOR MEM.
TIME OF ARRIVAL TOOL PLACES THIS LINE NEAR MEM AT 0215Z.
OTHER THAN A MVFR VSBY IN CONVECTIVE SHOWERS...VFR SHOULD PREVAIL
THROUGH THE EVENING. NAM LOW LEVEL MOISTURE PROGS SUGGEST A SLIGHT
CHANCE OF MVFR CIGS TOWARD SUNRISE...WITH BETTER CHANCES FOR MVFR
CIGS AT TUP.
PWB
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 75 89 75 92 / 40 50 30 30
MKL 73 88 74 89 / 40 50 40 50
JBR 74 88 73 91 / 60 50 50 40
TUP 73 90 74 91 / 30 40 30 30
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1058 PM CDT FRI AUG 31 2012
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
340 PM CDT FRI AUG 31 2012
MAIN FORECAST CONCERNS THIS PACKAGE...TEMPERATURES THROUGH THE
WEEKEND THEN RAIN CHANCES WITH A COLD FRONT LATER SUN NIGHT INTO
MON NIGHT.
DATA ANALYSIS AT 18Z HAD THE COLD FRONT IN FAR SOUTHERN WI TO
CENTRAL IA...MOVING VERY SLOWLY TO THE SOUTH. DRIER/COOLER AIR
CONTINUED TO SPREAD SOUTH ACROSS THE AREA BEHIND THE FRONT...WITH
DEW POINTS IN THE 50S ALONG/NORTH OF I-90 AND TEMPS IN THE 70S TO
LOWER 80S...AROUND 10F COOLER THAN THU. STILL RATHER SUMMERY ALONG/
SOUTH OF THE FRONT WITH DEW POINTS IN THE 60S AND TEMPS IN THE MID
80S-LOW 90S. OTHER THAN CIRRUS DEBRIS CLOUDS FROM ISAAC REMNANTS
SPREADING ACROSS PARTS OF IA AND NORTHERN IL...GENERALLY SUNNY
SKIES OVER THE UPPER MIDWEST AGAIN TODAY.
31.12Z MODELS LOOK TO HAVE INITIALIZED WELL...BUT FOR GFS SOME 5F-
10F TO HIGH WITH SFC DEW POINTS NEAR THE COLD FRONT ACROSS NORTHERN
IA INTO SOUTHERN WI. HOWEVER THIS LOOKS TO HAVE MINIMAL IMPACT ON
THE SHORT-TERM FCST THIS CYCLE...WITH SOLUTIONS RATHER SIMILAR FOR
TONIGHT INTO MON NIGHT. DPROG/DT OF 500MB HGTS AT 31.12Z SHOWED
MODEL RUNS OF 29.12Z AND 30.12Z VERIFIED REASONABLY WELL ACROSS NOAM
BUT MOST WERE A BIT WEAK AND SOUTHWEST WITH THE REMNANTS OF ISAAC
OVER OK/AR. STRONGER/SLOWER OF EARLIER RUNS WERE BETTER WITH THE
TROUGH/LOW OVER SOUTHERN BC. OVERALL BETTER RUN-TO-RUN CONSISTENCY
TO ECMWF. SOLUTIONS CONVERGING ON A TIGHTER COMPROMISE CONSENSUS
TONIGHT/SAT WITH BOTH THE LEFTOVERS OF ISAAC AND THE TROUGHING
MOVING ACROSS THE NORTHERN/CAN ROCKIES. TREND IS A LITTLE FASTER
WITH ISAAC TROUGH MOVING EAST INTO THE OH VALLEY SAT NIGHT/SUN.
COMPROMISE STILL FAVORED WITH THE TROUGH MOVING ACROSS INTO SOUTH-
CENTRAL CAN SAT NIGHT INTO MON NIGHT. BY MON NIGHT GEM APPEARS AS A
STRONG OUTLIER WITH THE NEXT TROUGH/ENERGY INTO THE UPPER MIDWEST.
NO MODEL WITH CLEARLY BETTER RUN-TO-RUN CONSISTENCY SAT THRU MON
NIGHT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED GFS REMAINED 5F TO
10F TOO HIGH WITH SFC DEW POINTS AHEAD OF/ALONG THE COLD FRONT AND
WAS TOO WET WITH LIGHT PRECIP NEAR THE COLD FRONT. OTHERWISE MODELS
LOOKED QUITE GOOD AT 18Z. WITH THE TREND TOWARD A COMPROMISE
CONSENSUS...FAVORED THE MODEL CONSENSUS THIS CYCLE. SHORT TERM FCST
CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
FOR THE SHORT TERM...WEATHER CONTINUES QUIET/DRY TONIGHT THRU SUN.
COLD FRONT WILL SLIP SOUTH OF THE AREA TONIGHT WITH THE DRIER/COOLER
AIRMASS CONTINUING TO SPREAD ACROSS THE AREA. RISING HGTS/INCREASING
SOUTHWEST FLOW AHEAD OF THE PAC NORTHWEST TROUGH HELP GIVE THE
REMNANTS OF ISAAC A KICK OFF TO THE EAST THRU THE WEEKEND. DEEPER
MOISTURE AND PRECIP SHIELD WITH THIS FEATURE CONTINUE TO TREND
SOUTH/EAST OF THE AREA WITH ONLY A COUPLE OF THE MORE NORTH/WEST
SOLUTIONS NOW CLIPPING THE SOUTH END OF GRANT COUNTY WITH -SHRA LATE
SAT NIGHT INTO SUN. WITH THE TREND THE LAST COUPLE CYCLES...LEFT
THESE PERIODS DRY. BIGGEST CONCERN WITH ISAAC REMNANTS IS THICKER
CIRRUS SHIELD OVER THE SOUTH END OF THE FCST AREA SAT...AND LOWERED
HIGH TEMPS A BIT THERE. DEPENDING ON HOW FAST THE SYSTEM EJECTS
EAST OF THE AREA SUN...MAY ALSO NEED TO LOWER HIGHS A BIT OVER THE
SOUTHEAST END ON SUN.
NEXT CONCERN IS THE COLD FRONT TO PUSH TOWARD THE AREA SUN NIGHT
THEN INTO/ACROSS THE AREA MON/MON NIGHT. FRONT GENERALLY WEAKENING
AS IT PUSHES ACROSS THE UPPER MIDWEST AS THE MAIN MID/UPPER LEVEL
DYNAMICS WITH THE SHORTWAVE EITHER WORKING TO FLATTEN THE RIDGING
ALOFT OR PASSING WELL NORTH OF THE FCST AREA. MODELS DO INCREASE
THE PW VALUES INTO THE 1.5 INCH RANGE AHEAD OF THE FRONT FOR LATE
SUN NIGHT/MON...WITH NAM ACTUALLY WETTER THAN GFS THIS TIME. LOWER
LEVEL THERMODYNAMIC FORCING ON THE WEAK SIDE BUT MODEL SOUNDINGS
INDICATE 1500-2500 J/KG OF SFC BASED CAPE AND MINIMAL CIN BY MID-DAY
ON MON. WITH THE FASTER MODEL CONSENSUS ADDED A BIT MORE SHRA/TSRA
CHANCE TO THE NORTHWEST END OF THE FCST AREA LATE SUN NIGHT. THEN
GIVEN THE INSTABILITY AND MINIMAL CIN WITH THE WEAKENING FRONT
MOVING IN...RAISED SHRA/TSRA CHANCES MON INTO THE 20-35 PERCENT
RANGE. MAY YET NEED A SMALL RAIN CHANCE MON EVENING BUT LEFT THIS
DRY FOR NOW. LATEST MODEL CONSENSUS BRINGS ANOTHER WEAK FEATURE
INTO THE AREA LATE MON NIGHT. WITH THE FIRST FRONT BARELY MAKING IT
THRU THE AREA MON...MOISTURE AHEAD OF IT REMAINS NEARBY AND WOULD
QUICKLY RETURN AHEAD OF THE NEXT FEATURE MON NIGHT. ADDED A SMALL
SHRA/TSRA CHANCE TO THE SOUTHWEST PORTIONS OF THE FCST AREA FOR
LATER MON NIGHT. IF LATEST TRENDS CONTINUE THIS WOULD NEED TO BE
EXPENDED TO MOST OR ALL OF THE FCST AREA.
FAVORING THE MODEL/ENSEMBLE CONSENSUS...GENERALLY USED A BLEND OF
THE NUMERICAL TEMP GUIDANCE FOR LOWS/HIGHS FOR TONIGHT THRU MON
NIGHT.
.LONG TERM...TUESDAY THROUGH THURSDAY
340 PM CDT FRI AUG 31 2012
31.00Z AND 31.12Z MEDIUM RANGE MODELS IN REASONABLY GOOD AGREEMENT
ON TUE WITH THE BROAD TROUGHING BECOMING ESTABLISHED OVER CAN.
THOUGH AS USUAL THERE ARE DETAIL DIFFERENCES WITH THE TIMING OF
TRACKABLE SHORTWAVE THRU THE NEARLY ZONAL FLOW NEAR THE US/CAN
BORDER. OVERALL TREND IS A BIT STRONGER WITH MORE TROUGHING OVER
ALB/SASKAT/MT/ DAKOTAS. CONSISTENCY IMPROVING FOR STRONGER SHORTWAVE
TROUGHING TO MOVE ACROSS THE DAKOTAS INTO THE UPPER MIDWEST
WED/THU...THEN BROAD...COOL LONGWAVE TROUGHING OVER MUCH OF THE
EASTERN CONUS BY FRI. BETWEEN MODEL CONSISTENCY IS IMPROVED IN THE
LONG-TERM BUT RUN-TO-RUN CONSISTENCY BEYOND TUE LESS THAN DESIRABLE
WHICH IS NOT UNEXPECTED GIVEN THE FAST QUASI-ZONAL FLOW PROGGED
ACROSS THE NORTHERN CONUS NEXT WEEK. LONG-TERM FCST CONFIDENCE GOOD
FOR THE PATTERN CHANGE AND COOLING NEXT WEEK BUT BELOW AVERAGE FOR
THE DAY-TO-DAY TROUGH/FRONTAL PASSAGES AND RAIN CHANCES. WITH THE
PATTERN TRANSITION...NEXT WEEK CONTINUES TO LOOK MORE ACTIVE. THE
NEXT STRONGER MID LEVEL TROUGH MOVES INTO THE NORTHERN PLAINS TUE...
WITH AT LEAST MDT DIVERGENCE ALOFT AHEAD OF IT SPREADING INTO THE
UPPER MIDWEST. WITH THE BETTER MODEL CONSISTENCY...SHRA/TSRA CHANCES
LOOK TO GO UP TUE. RAIN CHANCES CONTINUE TUE NIGHT/WED AS THE TROUGH
AXIS/ SFC FRONT AND STRONGER FORCING/LIFT MOVE ACROSS THE REGION. A
DRIER/ COOLER POST FRONTAL/POST TROUGH AIRMASS ALONG WITH WEAK HIGH
PRESSURE BUILD THU FOR A DRY DAY. PLENTY OF DETAIL DIFFERENCES BY
FRI BUT A SHRA/TSRA CHANCE SEEMS REASONABLE WITH THE APPROACH
OF ANOTHER STRONGER MID LEVEL TROUGH. MODEL CONSENSUS TEMPS ABOVE
NORMAL TUE TRENDING TO BELOW NORMAL BY THU/FRI LOOK GOOD.
&&
.AVIATION...THROUGH 06Z SUNDAY
1058 PM CDT FRI AUG 31 2012
WINDS HAVE GONE CALM AT KLSE WITH 01.01Z RAP BUFKIT SOUNDINGS
STILL SHOWING 30 KNOTS AT 015K FEET OVERNIGHT. THUS CONTINUED THE
MENTION OF LLWS AT KLSE. CIRRUS FROM THE REMNANTS OF ISAAC WILL
CONTINUE OVER THE TAF SITES THROUGH THE TAF PERIOD WITH VFR
CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
340 PM CDT FRI AUG 31 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...JLR
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
642 PM CDT FRI AUG 31 2012
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
340 PM CDT FRI AUG 31 2012
MAIN FORECAST CONCERNS THIS PACKAGE...TEMPERATURES THROUGH THE
WEEKEND THEN RAIN CHANCES WITH A COLD FRONT LATER SUN NIGHT INTO
MON NIGHT.
DATA ANALYSIS AT 18Z HAD THE COLD FRONT IN FAR SOUTHERN WI TO
CENTRAL IA...MOVING VERY SLOWLY TO THE SOUTH. DRIER/COOLER AIR
CONTINUED TO SPREAD SOUTH ACROSS THE AREA BEHIND THE FRONT...WITH
DEW POINTS IN THE 50S ALONG/NORTH OF I-90 AND TEMPS IN THE 70S TO
LOWER 80S...AROUND 10F COOLER THAN THU. STILL RATHER SUMMERY ALONG/
SOUTH OF THE FRONT WITH DEW POINTS IN THE 60S AND TEMPS IN THE MID
80S-LOW 90S. OTHER THAN CIRRUS DEBRIS CLOUDS FROM ISAAC REMNANTS
SPREADING ACROSS PARTS OF IA AND NORTHERN IL...GENERALLY SUNNY
SKIES OVER THE UPPER MIDWEST AGAIN TODAY.
31.12Z MODELS LOOK TO HAVE INITIALIZED WELL...BUT FOR GFS SOME 5F-
10F TO HIGH WITH SFC DEW POINTS NEAR THE COLD FRONT ACROSS NORTHERN
IA INTO SOUTHERN WI. HOWEVER THIS LOOKS TO HAVE MINIMAL IMPACT ON
THE SHORT-TERM FCST THIS CYCLE...WITH SOLUTIONS RATHER SIMILAR FOR
TONIGHT INTO MON NIGHT. DPROG/DT OF 500MB HGTS AT 31.12Z SHOWED
MODEL RUNS OF 29.12Z AND 30.12Z VERIFIED REASONABLY WELL ACROSS NOAM
BUT MOST WERE A BIT WEAK AND SOUTHWEST WITH THE REMNANTS OF ISAAC
OVER OK/AR. STRONGER/SLOWER OF EARLIER RUNS WERE BETTER WITH THE
TROUGH/LOW OVER SOUTHERN BC. OVERALL BETTER RUN-TO-RUN CONSISTENCY
TO ECMWF. SOLUTIONS CONVERGING ON A TIGHTER COMPROMISE CONSENSUS
TONIGHT/SAT WITH BOTH THE LEFTOVERS OF ISAAC AND THE TROUGHING
MOVING ACROSS THE NORTHERN/CAN ROCKIES. TREND IS A LITTLE FASTER
WITH ISAAC TROUGH MOVING EAST INTO THE OH VALLEY SAT NIGHT/SUN.
COMPROMISE STILL FAVORED WITH THE TROUGH MOVING ACROSS INTO SOUTH-
CENTRAL CAN SAT NIGHT INTO MON NIGHT. BY MON NIGHT GEM APPEARS AS A
STRONG OUTLIER WITH THE NEXT TROUGH/ENERGY INTO THE UPPER MIDWEST.
NO MODEL WITH CLEARLY BETTER RUN-TO-RUN CONSISTENCY SAT THRU MON
NIGHT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED GFS REMAINED 5F TO
10F TOO HIGH WITH SFC DEW POINTS AHEAD OF/ALONG THE COLD FRONT AND
WAS TOO WET WITH LIGHT PRECIP NEAR THE COLD FRONT. OTHERWISE MODELS
LOOKED QUITE GOOD AT 18Z. WITH THE TREND TOWARD A COMPROMISE
CONSENSUS...FAVORED THE MODEL CONSENSUS THIS CYCLE. SHORT TERM FCST
CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
FOR THE SHORT TERM...WEATHER CONTINUES QUIET/DRY TONIGHT THRU SUN.
COLD FRONT WILL SLIP SOUTH OF THE AREA TONIGHT WITH THE DRIER/COOLER
AIRMASS CONTINUING TO SPREAD ACROSS THE AREA. RISING HGTS/INCREASING
SOUTHWEST FLOW AHEAD OF THE PAC NORTHWEST TROUGH HELP GIVE THE
REMNANTS OF ISAAC A KICK OFF TO THE EAST THRU THE WEEKEND. DEEPER
MOISTURE AND PRECIP SHIELD WITH THIS FEATURE CONTINUE TO TREND
SOUTH/EAST OF THE AREA WITH ONLY A COUPLE OF THE MORE NORTH/WEST
SOLUTIONS NOW CLIPPING THE SOUTH END OF GRANT COUNTY WITH -SHRA LATE
SAT NIGHT INTO SUN. WITH THE TREND THE LAST COUPLE CYCLES...LEFT
THESE PERIODS DRY. BIGGEST CONCERN WITH ISAAC REMNANTS IS THICKER
CIRRUS SHIELD OVER THE SOUTH END OF THE FCST AREA SAT...AND LOWERED
HIGH TEMPS A BIT THERE. DEPENDING ON HOW FAST THE SYSTEM EJECTS
EAST OF THE AREA SUN...MAY ALSO NEED TO LOWER HIGHS A BIT OVER THE
SOUTHEAST END ON SUN.
NEXT CONCERN IS THE COLD FRONT TO PUSH TOWARD THE AREA SUN NIGHT
THEN INTO/ACROSS THE AREA MON/MON NIGHT. FRONT GENERALLY WEAKENING
AS IT PUSHES ACROSS THE UPPER MIDWEST AS THE MAIN MID/UPPER LEVEL
DYNAMICS WITH THE SHORTWAVE EITHER WORKING TO FLATTEN THE RIDGING
ALOFT OR PASSING WELL NORTH OF THE FCST AREA. MODELS DO INCREASE
THE PW VALUES INTO THE 1.5 INCH RANGE AHEAD OF THE FRONT FOR LATE
SUN NIGHT/MON...WITH NAM ACTUALLY WETTER THAN GFS THIS TIME. LOWER
LEVEL THERMODYNAMIC FORCING ON THE WEAK SIDE BUT MODEL SOUNDINGS
INDICATE 1500-2500 J/KG OF SFC BASED CAPE AND MINIMAL CIN BY MID-DAY
ON MON. WITH THE FASTER MODEL CONSENSUS ADDED A BIT MORE SHRA/TSRA
CHANCE TO THE NORTHWEST END OF THE FCST AREA LATE SUN NIGHT. THEN
GIVEN THE INSTABILITY AND MINIMAL CIN WITH THE WEAKENING FRONT
MOVING IN...RAISED SHRA/TSRA CHANCES MON INTO THE 20-35 PERCENT
RANGE. MAY YET NEED A SMALL RAIN CHANCE MON EVENING BUT LEFT THIS
DRY FOR NOW. LATEST MODEL CONSENSUS BRINGS ANOTHER WEAK FEATURE
INTO THE AREA LATE MON NIGHT. WITH THE FIRST FRONT BARELY MAKING IT
THRU THE AREA MON...MOISTURE AHEAD OF IT REMAINS NEARBY AND WOULD
QUICKLY RETURN AHEAD OF THE NEXT FEATURE MON NIGHT. ADDED A SMALL
SHRA/TSRA CHANCE TO THE SOUTHWEST PORTIONS OF THE FCST AREA FOR
LATER MON NIGHT. IF LATEST TRENDS CONTINUE THIS WOULD NEED TO BE
EXPENDED TO MOST OR ALL OF THE FCST AREA.
FAVORING THE MODEL/ENSEMBLE CONSENSUS...GENERALLY USED A BLEND OF
THE NUMERICAL TEMP GUIDANCE FOR LOWS/HIGHS FOR TONIGHT THRU MON
NIGHT.
.LONG TERM...TUESDAY THROUGH THURSDAY
340 PM CDT FRI AUG 31 2012
31.00Z AND 31.12Z MEDIUM RANGE MODELS IN REASONABLY GOOD AGREEMENT
ON TUE WITH THE BROAD TROUGHING BECOMING ESTABLISHED OVER CAN.
THOUGH AS USUAL THERE ARE DETAIL DIFFERENCES WITH THE TIMING OF
TRACKABLE SHORTWAVE THRU THE NEARLY ZONAL FLOW NEAR THE US/CAN
BORDER. OVERALL TREND IS A BIT STRONGER WITH MORE TROUGHING OVER
ALB/SASKAT/MT/ DAKOTAS. CONSISTENCY IMPROVING FOR STRONGER SHORTWAVE
TROUGHING TO MOVE ACROSS THE DAKOTAS INTO THE UPPER MIDWEST
WED/THU...THEN BROAD...COOL LONGWAVE TROUGHING OVER MUCH OF THE
EASTERN CONUS BY FRI. BETWEEN MODEL CONSISTENCY IS IMPROVED IN THE
LONG-TERM BUT RUN-TO-RUN CONSISTENCY BEYOND TUE LESS THAN DESIRABLE
WHICH IS NOT UNEXPECTED GIVEN THE FAST QUASI-ZONAL FLOW PROGGED
ACROSS THE NORTHERN CONUS NEXT WEEK. LONG-TERM FCST CONFIDENCE GOOD
FOR THE PATTERN CHANGE AND COOLING NEXT WEEK BUT BELOW AVERAGE FOR
THE DAY-TO-DAY TROUGH/FRONTAL PASSAGES AND RAIN CHANCES. WITH THE
PATTERN TRANSITION...NEXT WEEK CONTINUES TO LOOK MORE ACTIVE. THE
NEXT STRONGER MID LEVEL TROUGH MOVES INTO THE NORTHERN PLAINS TUE...
WITH AT LEAST MDT DIVERGENCE ALOFT AHEAD OF IT SPREADING INTO THE
UPPER MIDWEST. WITH THE BETTER MODEL CONSISTENCY...SHRA/TSRA CHANCES
LOOK TO GO UP TUE. RAIN CHANCES CONTINUE TUE NIGHT/WED AS THE TROUGH
AXIS/ SFC FRONT AND STRONGER FORCING/LIFT MOVE ACROSS THE REGION. A
DRIER/ COOLER POST FRONTAL/POST TROUGH AIRMASS ALONG WITH WEAK HIGH
PRESSURE BUILD THU FOR A DRY DAY. PLENTY OF DETAIL DIFFERENCES BY
FRI BUT A SHRA/TSRA CHANCE SEEMS REASONABLE WITH THE APPROACH
OF ANOTHER STRONGER MID LEVEL TROUGH. MODEL CONSENSUS TEMPS ABOVE
NORMAL TUE TRENDING TO BELOW NORMAL BY THU/FRI LOOK GOOD.
&&
.AVIATION...TONIGHT AND SATURDAY
641 PM CDT FRI AUG 31 2012
HIGH CLOUDS FROM THE REMNANTS OF ISAAC HAS PUSHED AS FAR NORTH AS
BOTH TAF SITES. THESE HIGH CLOUDS WILL LIKELY CONTINUE THROUGH THE
TAF PERIOD. WINDS WILL DECOUPLE THIS EVENING AS THE PRESSURE
GRADIENT REMAINS WEAK. 31.21Z RAP AND 31.18Z NAM BUFKIT SOUNDINGS
SHOWING LOW LEVEL WINDS AROUND 1K FEET TO INCREASE TO 30 KNOTS
OVERNIGHT AND THUS PRODUCING MARGINAL LOW LEVEL WIND SHEAR AT
KLSE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
340 PM CDT FRI AUG 31 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS DENVER CO
311 AM MDT SAT SEP 1 2012
.SHORT TERM...SAME OLD STORY AS THE UPPER LEVEL RIDGE CONTINUES
OVER THE AREA WITH SSW FLOW ALOFT. SUBTROPICAL MOISTURE WILL
CONTINUE TO AFFECT THE MTNS WITH SCT AFTN TSTMS WHILE THE HIGHER
VALLEYS AND FOOTHILLS SEE WDLY SCT STORMS. OVER NERN CO IT WILL
REMAIN HOT AND DRY ALTHOUGH OUTFLOW BOUNDARIES FROM HIGHER TERRAIN
CONVECTION MAY TRIGGER A FEW STORMS MAINLY WEST OF I-25. AFTN
HIGHS WILL BE IN THE 90S ACROSS NERN CO WITH HIGH FIRE DANGER.
GUSTY SOUTH WINDS WILL BE HIGH ENOUGH FOR RED FLAG CONDITIONS OVER
THE PLAINS. FOR TONIGHT SOME LINGERING SHOWERS/TSTMS WILL CONTINUE
OVER THE HIGHER TERRAIN THRU THE EARLY EVENING HOURS WITH MOST
ACTIVITY ENDING BY MIDNIGHT.
.LONG TERM...FAIRLY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED
OVER THE CWA SUNDAY THROUGH MONDAY NIGHT. THE SYNOPTIC SCALE ENERGY
IS WEAK SUNDAY THROUGH MONDAY NIGHT. THE LOW LEVEL PRESSURE AND
WIND FIELDS SHOW A WEAK COLD FRONT TO MOVE INTO THE PLAINS ON
SUNDAY. WEAK UPSLOPE IS PROGGED FOR THE PLAINS INTO SUNDAY
EVENING. ON MONDAY...THE GRADIENT IS WEAK SO NORMAL DIURNAL WIND
PATTERNS SHOULD PREVAIL. FOR MOISTURE...THEN IS SOME PROGGED
...MAINLY IN THE UPPER AND MID LEVELS ON SUNDAY INTO MONDAY
EVENING. DEW POINT PROGGS ARE MAINLY IN THE 40S F OVER THE PLAINS
...WITH 30S F IN THE MOUNTAINS ON SUNDAY...AND A TAD LOWER ON
MONDAY. THE GFS IS A BIT HIGHER THAN THE NAM. PRECIPITABLE WATER
VALUES ARE IN HE 0.90-1.00 INCH RANGE ON SUNDAY...THEN THE 0.75-0.85
INCH RANGE ON MONDAY. THERE IS A TAD OF CAPE PROGGED OVER THE
MOUNTAINS LATE DAY SUNDAY...NOTHING FOR THE PLAINS. BY LATE DAY
MONDAY...THE NAM ONLY HAS LIMITED CAPE OVER THE MOUNTAINS...WHILE
THE GFS HAS A TAD OVER THE FAR EAST. THE QPF FIELDS HAVE A TAD OF
MEASURABLE RAINFALL PROGGED OVER THE MOUNTAINS LATE DAY SUNDAY.
THERE IS EVEN LESS INDICATED FOR MONDAY. FOR POPS...WILL GO WITH
"CHANCE"S IN THE MOUNTAINS SUNDAY AFTERNOON AND EVENING...NOTHING
FOR THE PLAINS. FOR LATE DAY MONDAY...WILL GO WITH 20% IN THE
MOUNTAINS...10%S ELSEWHERE. CONCERNING FIRE WEATHER...WILL GO WITH
NO HIGHLIGHTS SUNDAY FOR THE PLAINS BECAUSE THE WINDS DON`T SEEM TO
BE AN ISSUE...AND RELATIVE HUMIDITIES WILL BE MARGINAL. IT WILL BE A
BIT COOLER SUNDAY EVEN THOUGH MOISTURE IS NOT GREAT. FOR
TEMPERATURES...SUNDAY`S HIGHS SHOULD BE 1.0-2.5 C COOLER THAN
SATURDAY`S HIGHS. MONDAY`S HIGHS MAY BE A TAD WARMER THAN
SUNDAY`S. FOR THE LATER DAYS...TUESDAY THROUGH FRIDAY...MODELS HAVE
A PRETTY FLAT UPPER RIDGE CENTERED TO THE SOUTH OF COLORADO WITH
MAINLY ZONAL FLOW ALOFT TUESDAY INTO THURSDAY NIGHT. ON FRIDAY...
BOTH THE GFS AND ECMWF SHOW A VIGOROUS UPPER TROUGH MOVING
SOUTHEASTWARD TO OUR NORTH AND NORTHEAST. THE FLOW ALOFT BECOMES
NORTHWESTERLY ON FRIDAY...AND BOTH MODELS SHOW A SIGNIFICANT COLD
FRONT TO MOVE IN THE CWA. THE GFS AND ECMWF ALSO SHOW A WEAKER COLD
FRONT TO MOVE IN ON WEDNESDAY. MOISTURE IS SPARSE FOR ALL THE
DAYS.
&&
.AVIATION...WINDS HAVE REMAINED SOUTH EARLY THIS MORNING AND
SHOULD BE SSW THRU LATE MORNING. BY 18Z LATEST HRRR SHOWS A WK
DENVER CYCLONE NR THE AIRPORT WITH LIGHT NLY WINDS DEVELOPING THRU
21Z. AFTER 21Z THE HRRR SHOWS AN OUTFLOW BNDRY MOVING ACROSS THE
AIRPORT FM CONVECTION OVER THE FOOTHILLS WITH WINDS BECOMING WNW.
COULD BRIEFLY SEE SOME WIND GUSTS TO 25 MPH OR SO WITH THIS BNDRY.
FOR NOW WILL NOT MENTION ANY TSTM ACTIVITY AT DIA. BY EARLY EVENING
WILL SHIFT WINDS BACK TO THE SW AND KEEP THEM THAT WAY OVERNIGHT.
A WK CDFNT WILL MOVE INTO THE AREA AFTER 12Z SUN WITH WINDS
BECOMING NLY BY 15Z.
&&
.HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE IN
THE BURN AREAS THIS AFTERNOON WITH RAINFALL AMOUNTS AROUND A
QUARTER INCH OR LESS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 11 AM THIS MORNING TO 7 PM MDT THIS
EVENING FOR COZ242-244>246-248>251.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
330 AM EDT SAT SEP 01 2012
.SYNOPSIS...
07Z WATER VAPOR AND H4 RAP ANALYSIS SHOW MUCH OF THE SOUTHEASTERN
CONUS UNDERNEATH A STRONG 592-595DM UPPER RIDGE. AN NWP ADVERTISED
INTRUSION OF VERY DRY MID/UPPER LEVEL AIR IS NOW SEEN QUITE WELL ON
WV IMAGERY ROTATING DOWN THE EASTERN CIRCULATION OF THE UPPER RIDGE
AND BEGINNING TO ARRIVE OVER THE FL PENINSULA. THIS INTRUSION OF
UNSEASONABLY DRY AIR ABOVE THE SURFACE WILL BE THE MAIN PLAYER IN
OUR FORECAST THROUGH THE WEEKEND. THE 00Z KTBW SOUNDING PROFILE
STILL SHOWED A PW OF AROUND 1.8" (WHICH IS RIGHT ABOUT WHERE WE
SHOULD BE FOR THIS TIME OF YEAR)...HOWEVER THE INFLUENCE OF THE
UPPER RIDGE CAN BE SEEN IN WARM 500MB TEMPS OF -4C TO -5C. THESE
TEMPS HELPED TO PARTIALLY CAP THE COLUMN AND KEPT CONVECTIVE
COVERAGE ON FRIDAY TO A MINIMUM.
AT THE SURFACE...THE SUBTROPICAL RIDGE AXIS IS ALIGNED JUST TO OUR
NORTH NEAR THE I-10 CORRIDOR RESULTING IN A LIGHT NORTHEAST TO
EASTERLY LOW LEVEL FLOW.
CONDITIONS ARE DRY OUT THERE WITH LITTLE TO NO ACTIVITY SEEN ON
REGIONAL RADARS...AND SKIES ARE TRENDING TOWARDS CLEAR FROM NE TO SW
AS THE DRIER AIR ARRIVES ALOFT.
&&
.SHORT TERM (TODAY THROUGH MONDAY)...
TODAY...THE MID/UPPER RIDGE WILL CONTINUE OVERHEAD BUT SLOWLY WEAKEN
THROUGH THE DAY ALLOWING HEIGHTS TO COME DOWN A FEW DM. OVERALL WILL
SEE A DROP IN THE SYNOPTIC SUPPRESSION ON THE COLUMN...HOWEVER THE
ARRIVAL OF INCREASINGLY DRY AIR ABOVE 700MB WILL ACT TO
SIGNIFICANTLY LIMIT CONVECTION. CROSS-SECTIONS ALONG THE FL WEST
COAST SHOW THIS TONGUE OF DRIER AIR DESCENDING DOWN THROUGH THE
COLUMN AS WE HEAD INTO THE AFTERNOON MAKING ANY CONVECTION THAT DOES
FIRE ALONG THE SEA-BREEZE RATHER SHALLOW. DID GO WITH A 20% SLIGHT
CHANCE POP FOR THESE ISOLATED CELLS...HOWEVER THE COVERAGE OF
RAINFALL TODAY WILL LIKELY BE EVEN LOWER THAN THIS. WITH EASTERLY
LOW LEVEL FLOW...THE SEA-BREEZE WILL ONCE AGAIN BE PINNED TO THE
COAST. THE LACK OF DEVELOPING ONSHORE FLOW AND THE STACKED RIDGING
SHOULD ALLOW TEMPERATURES TO EASILY CLIMB INTO THE LOWER/MIDDLE 90S.
TONIGHT...ANY ISOLATED CONVECTIVE CELLS WILL PUSH OFFSHORE DURING
THE EVENING HOURS LEAVING A DRY FORECAST FOR OUR LAND ZONES.
TEMPERATURES WILL ACTUALLY BECOME RATHER COMFORTABLE FOR THIS TIME
OF YEAR...WITH SOME OF THE NORMALLY COOLER MOS STATIONS SHOWING
POTENTIAL FOR LOWS AROUND 70.
SUNDAY...UPPER RIDGE OVERHEAD WILL CONTINUE TO WEAKEN IN RESPONSE TO
A STRONG SHORTWAVE TROUGH DROPPING SOUTHEASTWARD OUT OF THE TN
VALLEY...AND A CLOSED UPPER LOW APPROACHING THE PENINSULA FROM THE
EAST. MUCH OF SUNDAY LOOKS LIKE YET ANOTHER DAY WITH AN UNSEASONABLY
DRY COLUMN OVER OUR HEADS. IN FACT...THE DEPTH OF THE DRY AIR IS
SHOWN BY MANY OF THE GUIDANCE MEMBERS TO BE MAXIMIZED DURING THE
DAYLIGHT HOURS OF SUNDAY. THIS EXCESSIVELY DRY COLUMN ABOVE 850MB
WILL BE OF GREATEST INFLUENCE OVER THE CENTRAL AND NORTHERN PORTIONS
OF THE FORECAST AREA. DOWN TOWARD FORT MYERS...SOME RECOVERY IN THE
MOISTURE FIELDS IS LIKELY BY LATE AFTERNOON IN CLOSER PROXIMITY TO
THE APPROACHING UPPER LOW. IF AN ISOLATED SHOWER OR 2 IS TO FORM
SUNDAY AFTERNOON...IT WOULD BE DOWN TOWARD THIS MOISTURE RETURN. THE
REMAINDER OF THE FORECAST AREA WILL BE UNDER A VERY HOSTILE
ENVIRONMENT FOR DEEP CONVECTION...AND WILL LEAVE POPS AT 10% OR
LESS.
MONDAY...UPPER LOW FEATURE IS PROGGED BY THE GLOBAL GUIDANCE TO
BECOME CENTERED OVER THE SOUTHERN FL PENINSULA BY MONDAY EVENING.
HIGHEST RAIN CHANCES (30-40%) WILL EXIST SOUTH OF THE TAMPA BAY AREA
WHERE THE SYNOPTIC SUPPORT FOR LIFT AHEAD OF THE LOW CENTER AND
COOLEST ARRIVING MID-LEVEL TEMPERATURES WILL EXIST. FROM TAMPA BAY
NORTHWARD...THESE INFLUENCES WILL BE LESS...AND AT LEAST SOME
RESIDUAL DRY AIR ALOFT WILL STILL BE IN PLACE. WILL INTRODUCE SLIGHT
CHANCE POPS BACK TO THE FORECAST...BUT REALLY ANTICIPATE ANOTHER DRY
DAY. THE UPPER LOW AND ASSOCIATED BETTER RAIN CHANCES WILL MIGRATE
NORTHWARD BY TUESDAY. A MID-LEVEL COLD POOL UNDERNEATH THE UPPER LOW
(-8 TO -10C) WILL BE SPREADING OVER THE SOUTHERN THIRD OF THE
PENINSULA BY LATE MONDAY. THIS ENHANCED INSTABILITY WILL BRING THE
POTENTIAL FOR A FEW STRONGER STORMS OVER THE SOUTHERN THIRD OF THE
FORECAST AREA.
&&
.LONG TERM (MONDAY NIGHT - FRIDAY)...WE WILL TRANSITION BACK INTO A
WETTER WEATHER PATTERN DURING THE EXTENDED TIME FRAME AS THE RIDGE
OF HIGH PRESSURE WEAKENS AND A TROPICAL UPPER-TROPOSPHERIC TROUGH
/TUTT/ AND ITS ASSOCIATED LOW PRESSURE AREA MOVE WESTWARD TOWARD THE
PENINSULA. BOTH THE GFS AND ECMWF SHOW THIS LOW APPROACHING SOUTH
FLORIDA MONDAY NIGHT AND TUESDAY. THE GFS THEN HOLDS THIS FEATURE
TOGETHER BETTER THAN THE ECMWF...LIFTING IT SLOWLY NORTHWARD OVER
FLORIDA THROUGH WEDNESDAY OR WEDNESDAY NIGHT. THE TUTT LOW THEN GETS
PICKED UP BY A BROAD TROUGH DIGGING EASTWARD TOWARD THE ATLANTIC
COAST. DURING THIS TIME...A FRONTAL BOUNDARY IS FORECAST TO DROP
INTO THE SOUTHEASTERN STATES...PUSHING THE SUB-TROPICAL RIDGE TO OUR
SOUTH AND TURNING OUR WINDS MORE WESTERLY FOR THURSDAY AND
ESPECIALLY FRIDAY. IN SHORT...MOISTURE WILL BE INCREASING AS THE
TUTT LOW APPROACHES. COOLER MID-LEVEL TEMPS AND LOWER 500MB HEIGHTS
WILL BE MOVING IN FROM THE EAST. OUR EASTERLY WINDS RELAX ENOUGH TO
ALLOW SEA BREEZES TO PUSH INLAND A WAYS TUESDAY AND WEDNESDAY...
FOLLOWED BY STRONGER WESTERLY FLOW DEVELOPING THURSDAY AND FRIDAY.
ALL OF THESE FACTORS SUGGEST RAIN CHANCES WILL INCREASE TO AT LEAST
NORMAL LEVELS...WHICH WOULD BE AROUND 40 TO 50 PERCENT FOR THE FIRST
PART OF SEPTEMBER.
FOR THE FORECAST...LOOK FOR THE BEST RAIN CHANCES TO BE ALONG AND
EAST OF I-75 ON TUESDAY AS SEA BREEZES MOVE ONLY SLOWLY INLAND. BY
WEDNESDAY...THE RIDGE IS BREAKING DOWN SO BEST RAIN CHANCES BEGIN TO
SHIFT INLAND DURING THE AFTERNOON. FOR THURSDAY AND
FRIDAY...WESTERLY FLOW WILL PUSH OUR SEA BREEZE RAPIDLY INLAND AND
TOWARD THE EAST COAST DURING THE AFTERNOON. OTHER THAN SOME SHOWERS
NEAR THE COAST EACH MORNING...THE BEST RAIN CHANCES WILL BE WELL
INLAND DURING THE AFTERNOON. TEMPERATURES WILL RUN WITHIN A COUPLE
DEGREES OF NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION...
VFR NEXT 24 HOURS. VERY ISOLATED AFTERNOON SHOWERS OR STORMS ARE
POSSIBLE...BUT OVERALL COVERAGE TOO LOW TO MENTION IN TAFS AT THIS
TIME.
&&
.MARINE...
THE SUBTROPICAL RIDGE AXIS WILL HOLD IN POSITION OF THE NORTHEAST
GULF OF MEXICO THROUGH THE WEEKEND AND THEN SETTLE SLOWLY SOUTHWARD
INTO THE MIDDLE PORTION OF NEXT WEEK. THE CLOSE PROXIMITY OF THE
RIDGE AXIS WILL KEEP WINDS AND SEAS BELOW HEADLINE CRITERIA THROUGH
THE FORECAST PERIOD.
&&
.FIRE WEATHER...
HIGH PRESSURE TO OUR NORTH TODAY WILL SETTLE SOUTHWARD INTO THE
REGION DURING THE SECOND HALF OF THE WEEKEND...AND THEN REMAIN IN
PLACE THROUGH AT LEAST TUESDAY. RAIN CHANCES AND LOW LEVEL MOISTURE
WILL BE LOWER THAN NORMAL FOR EARLY SEPTEMBER DURING THE NEXT COUPLE
OF DAYS...HOWEVER NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 92 75 91 75 / 20 10 10 10
FMY 92 73 92 75 / 20 10 10 10
GIF 93 71 93 71 / 10 10 10 0
SRQ 91 73 89 73 / 20 10 10 10
BKV 92 70 91 68 / 20 10 10 10
SPG 93 79 91 78 / 20 10 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
326 AM EDT SAT SEP 1 2012
.DISCUSSION...
...RIP CURRENT RISK INCREASING THIS WEEKEND...
CURRENT...
N/NE PENINSULA FLOW REGIME DUE TO A DEEP ANTICYCLONE CENTERED OVER
THE DEEP SOUTH AND EXTENDING INTO THE CENTRAL GOMEX. EVENING
SOUNDINGS SHOWED A SIMILAR PROFILE STATEWIDE: MODERATE TO HIGH PWAT
VALUES BTWN 1.7"-2.0" BUT DISTRIBUTED THRU THE COLUMN MORE OR LESS
EVENLY...FAIRLY DRY MID LYRS WITH DEWPOINT DEPRESSIONS GENERALLY ABV
5C AND IN MANY LYRS WELL OVER 10C...VERY WEAK MID LVL LAPSE RATES
BTWN 5.0-5.5C/KM...H70 TEMPS ARND 10C...H50 TEMPS ARND -6C.
LATEST RAP ANALYSIS SHOWS LITTLE IN THE WAY OF MOISTURE OR DYNAMIC
LIFT: H100-H70 MEAN RH AOB 70PCT...H85-H50 MEAN RH BTWN 70-80PCT BUT
WITH VALUES BLO 50PCT ADVECTING ONSHORE...WEAK PVA DUE TO A THIN
BAND OF MID LVL VORTICITY OFFSHORE EMBEDDED WITHIN DEEP NE
FLOW...UPR LVL WIND PATTERN NEUTRAL OR WEAKLY CONVERGENT. RADAR
DETECTING ISOLD SHRAS NOTED OVER THE GULF STREAM ADVECTING ONSHORE S
OF FT. PIERCE INLET.
TODAY/TONIGHT...
DRY/STABLE NE FLOW PATTERN WILL CONTINUE THRU DAWN SUNDAY AS THE
ANTICYCLONE TO THE N RETROGRADES INTO THE GOMEX. FCST WILL BE
LARGELY DRY ONCE AGAIN AS THE AIRMASS IS TOO STABLE ALOFT TO SUPPORT
ANY MEANINGFUL VERTICAL MOTION. ONLY MESOSCALE BNDRY COLLISIONS OR
CONVECTIVE TEMPS COULD DO THIS. HOWEVER...THE NE FLOW WILL ENSURE
MOST BNDRY COLLISIONS WOULD OCCUR OVER W FL...WHILE MID/UPR LVL
DRY AIR ADVECTION WOULD EVAPORATE ANY CU TOWERS LONG BEFORE THEY
COULD BUILD ENOUGH TO SUPPORT PRECIP.
ONE PSBL EXCEPTION WOULD BE THE TREASURE COAST S OF KVRB WHERE A LOW
LVL POCKET OF MOISTURE N OF THE BAHAMAS COULD ALLOW A FEW BRIEF
SHRAS TO PUSH ONSHORE. HOWEVER...THESE SHOULD DISSIPATE ARND
SUNRISE AS LAND/SEA SFC/LOW LVL WND SPEEDS BECOME DIVERGENT WITH
THE FORMATION OF THE EAST COAST SEA BREEZE. FURTHERMORE...GIVEN
THE OVERALL WEAK DYNAMIC SUPPORT...ANY SHRAS THAT MIGHT MAKE IT
ONSHORE WOULD DISSIPATE RAPIDLY AND WOULD HAVE NEGLIGIBLE IMPACT.
DEEP ONSHORE FLOW WILL KEEP MAX TEMPS WITHIN A DEG OR TWO OF CLIMO
AVG (U80S/L90S)...MIN TEMPS A FEW DEG ABV AVG (M70S).
SUN-MON...
AXIS OF SURFACE HIGH PRESSURE RIDGE WILL EXTEND NORTH OF THE AREA
WHICH WILL RESULT IN A LIGHT ONSHORE FLOW BOTH DAYS. UPPER LEVEL
RIDGE AXIS WILL EXTEND NORTH OF THE AREA ON SUNDAY...WHILE UPPER
LEVEL LOW DRIFTS WEST ACROSS THE NORTHERN BAHAMAS. ZONE OF UPPER
LEVEL CONVERGENCE BETWEEN THESE FEATURES WILL PROVIDE
SUBSIDENCE/DRYING AND IT LOOKS TOO DRY FOR ANY RAIN OVER LAND.
THE GFS HAS TRENDED FARTHER WEST WITH THE UPPER LEVEL LOW ON MON
AND NOW MOVES IT TO NEAR THE SOUTHEAST FLORIDA COAST. WITH COLDER
TEMPS ALOFT AND SLIGHTLY INCREASED MOISTURE IN OUR FAR SOUTHERN
COUNTIES...HAVE ADDED A 20 PERCENT POP. THE NORTHERN HALF SHOULD
REMAIN DRY THOUGH WITH PRECIPITABLE WATER A LITTLE BIT EITHER
SIDE OF AN INCH.
MAX TEMPS WILL CONTINUE IN THE LOWER 90S INLAND AND UPPER 80S
ALONG THE COAST. THE DRIER AIR ACROSS THE NORTH WILL KEEP
AFTERNOON RH VALUES LOWER THAN RECENT DAYS.
A SMALL LONG PERIOD SWELL FROM DISTANT TROPICAL CYCLONE KIRK
SHOULD AFFECT THE COASTAL WATERS SUNDAY. THE LATEST WAVE WATCH
MODEL RUN SHOWS A SMALL SWELL FROM DISTANT TROPICAL CYCLONE LESLIE
REACHING THE WATERS LATE MON. THIS WILL LIKELY RESULT IN A
MODERATE TO HIGH RISK OF DANGEROUS RIP CURRENTS.
TUE-SAT...
AT THE SURFACE...A HIGH PRESSURE RIDGE AXIS WILL SETTLE SLOWLY
SOUTH AS FRONTAL TROUGH MOVES INTO THE SOUTHEAST STATES DURING MID
WEEK. THE RIDGE AXIS SHOULD PUSH INTO THE SOUTHERN PENINSULA BY
WED.
THE UPPER LEVEL LOW IS ONLY FORECAST TO DRIFT SLOWLY NORTH THROUGH
LATE WEEK. DEEP LAYER MOISTURE DOES NOT LOOK VERY HIGH...BUT WITH
COOLER TEMPS ALOFT...EXPECT SCATTERED AFTERNOON STORMS ACROSS ALL
AREAS BY WED. STEERING LEVEL FLOW WILL ATTAIN A WESTERLY COMPONENT
AND CONTINUE THE 30-40 PERCENT POPS THROUGH LATE WEEK.
SWELLS FROM SLOW MOVING TROPICAL CYCLONE LESLIE WILL LIKELY
CONTINUE THROUGH THE END OF THE WEEK AND PRODUCE A HIGH RISK OF
DANGEROUS RIP CURRENTS.
&&
.AVIATION...
ALL SITES VFR UNLESS OTHERWISE NOTED: THRU 01/12Z...KFPR-KSUA BRIEF
MVFR CIGS/VSBYS IN ISOLD PASSING SHRAS...N OF KISM-KDAB LCL MVFR
VSBYS IN BR.
&&
.MARINE...
TODAY-TONIGHT...RIDGE AXIS CENTERED OVER THE DEEP SOUTH WILL
GENERATE A GENTLE TO MODERATE NE BREEZE. SEAS GENERALLY AOB 2FT.
THE LEADING EDGE OF A LARGE SWELL TRAIN GENERATED BY DISTANT T.C.
KIRK MAY REACH THE OFFSHORE LEG IN THE PREDAWN HRS OF SUNDAY
MRNG...PUSHING SEAS UP TO 2-3FT. BRIEF ISOLD NOCTURNAL SHRAS OVER
THE GULF STREAM S OF SEBASTIAN INLET.
SUN-MON...HIGH PRESSURE RIDGE AXIS JUST NORTH OF THE WATERS WILL
PROVIDE A LIGHT ONSHORE WIND FLOW. THERE IS A SMALL CHANCE FOR
SHOWERS OR STORMS ACROSS THE SOUTHERN WATERS...MAINLY ON MON.
TRAVERSING INLETS DURING THE OUTGOING TIDE MAY BECOME HAZARDOUS FOR
SMALL CRAFT DUE TO A SMALL LONG PERIOD SWELL FROM DISTANT TROPICAL
CYCLONES KIRK AND LESLIE.
TUE-WED...HIGH PRESSURE RIDGE AXIS WILL SETTLE OVER THE WATERS
TUE AND THEN INTO SOUTH FLORIDA WED...LEADING TO A MORE SOUTHERLY
FLOW BECOMING SOUTHWEST ON WED. WIND SPEEDS SHOULD BE 10 KNOTS OR
LESS. SCATTERED AFTERNOON STORMS ARE EXPECTED TO START PUSHING
BACK ACROSS THE COAST ON WED.
TRAVERSING INLETS DURING THE OUTGOING TIDE WILL BE HAZARDOUS FOR
SMALL CRAFT DUE TO BUILDING LONG PERIOD SWELL FROM DISTANT
TROPICAL CYCLONE LESLIE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 89 74 89 70 / 10 10 10 10
MCO 92 74 92 70 / 10 10 10 10
MLB 89 74 87 72 / 10 10 10 10
VRB 88 75 87 71 / 10 10 10 10
LEE 93 74 93 71 / 10 10 10 10
SFB 92 74 91 71 / 10 10 10 10
ORL 92 74 91 72 / 10 10 10 10
FPR 88 75 87 72 / 10 10 10 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM....LASCODY
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
323 AM CDT SAT SEP 1 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 06Z...
* NORTHEAST WINDS WITH GUSTS ABOVE 15 KTS TODAY BECOMING MORE
EASTERLY TONIGHT.
* TIMING OF RAIN AFFECTING TODAY/TONIGHT.
* POTENTIAL FOR MVFR CIG/VIS IF RAIN PERSISTS.
RATZER
//DISCUSSION...UPDATED 06Z...
TROPICAL DEPRESSION ISAAC WAS LOCATED OVER WEST CENTRAL MISSOURI
AT 05Z...WITH AN AREA OF MODERATE RAIN EXTENDING FROM FAR EASTERN
KANSAS ACROSS NORTHERN MISSOURI INTO MUCH OF CENTRAL/SOUTHERN IL.
ISAAC IS EXPECTED TO DRIFT VERY SLOWLY EAST INTO SOUTHERN IL
THROUGH SUNDAY MORNING. MAIN FORECAST QUESTION FOR THE TAFS IS
WHERE THE NORTHERN PERIPHERY OF THE RAIN ASSOCIATED WITH THIS
SYSTEM LAYS OUT IN RELATION TO THE TERMINAL LOCATIONS...AND THE
POTENTIAL FOR MVFR OR EVEN IFR CIG/VIS CONDITIONS IN THE AREAS
WHICH SEE PERSISTENT RAINFALL. 00Z HIGH RESOLUTION MODEL GUIDANCE
SUGGESTS THAT THE NORTHERN EDGE OF THE RAIN AREA WILL BE
APPROXIMATELY THROUGH THE INTERSTATE 88 CORRIDOR ACROSS NORTHERN
IL WITH AREAS TO THE NORTH LESS LIKELY TO SEE PERSISTENT RAIN AND
ASSOCIATED CIG/VIS REDUCTIONS. THIS MAKES FOR A TRICKY FORECAST
WITH TERMINALS IN/NEAR THE EXPECTED SHARP GRADIENT OF LITTLE/NO
RAIN TO THE NORTH AND CONSIDERABLE RAIN FARTHER TO THE SOUTH.
RFD WILL HAVE THE LOWEST LIKELIHOOD OF SEEING ANY PROLONGED PERIOD
OF RAIN AND LOWER CIG/VIS...WITH AN EXPECTATION THAT ORD/DPA WILL
PERHAPS SEE A FEW PERIODS OF LIGHTER RAIN AND GYY FARTHEST TO THE
SOUTH WOULD HAVE THE GREATEST THREAT OF LONGER DURATION RA/SHRA
AND ALSO LOWER CIG/VIS CONDITIONS. FOR NORTHERN TERMINALS...THE
GREATEST POTENTIAL FOR SOME RAIN TO AFFECT RFD/DPA/ORD/MDW WOULD
BE DURING THE AFTERNOON HOURS AS LOW/MID LEVEL MOISTURE CONVERGENCE
EXPANDS NORTHEASTWARD PER MODELS. HIGH-RES GUIDANCE INDICATES SOME
SHOWERS MAY AFFECT GYY AS EARLY AS THIS MORNING...WITH SOME WEAK
RADAR ECHOES ALREADY DEVELOPING SOUTH OF THE KANKAKEE RIVER VALLY
INTO INDIANA.
WINDS ARE EXPECTED TO REMAIN EAST-NORTHEAST THROUGH THE PERIOD AS
THE SURFACE LOW PRESSURE CIRCULATION MOVES SLOWLY ACROSS MISSOURI
AND DOWNSTATE IL. SOME GUSTS INTO THE 15-20 KT RANGE APPEAR
POSSIBLE MAINLY DURING THE DAY TODAY...THOUGH WEAK LOW LEVEL LAPSE
RATES SUGGEST GUSTS MAY BE SOMEWHAT SPORADIC.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS. MEDIUM CONFIDENCE GUST SPEEDS.
* MEDIUM CONFIDENCE IN RAIN POTENTIAL AND CIG/VIS TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...OCCASIONAL RA. MVFR PSBL IFR CIGS.
MONDAY...CHC RA ISO TSRA. MVFR PSBL.
TUESDAY THROUGH WEDNESDAY...VFR. CHC SHRA/ISO TSRA W/MVFR CIGS.
THURSDAY...VFR.
BEACHLER
&&
.MARINE...
320 AM CDT
THE MAIN MARINE FORECAST CONCERNS CONTINUE TO FOCUS ON WINDS
ASSOCIATED WITH THE REMNANTS OF TROPICAL DEPRESSION ISAAC...AS THE
LOW PRESSURE CENTER DRIFTS VERY SLOWLY FROM CENTRAL MISSOURI INTO
SOUTHERN ILLINOIS THROUGH EARLY SUNDAY...THEN SLOWLY WEAKENS OVER
THE OHIO VALLEY INTO MONDAY. EAST-NORTHEAST WINDS ACROSS THE
SOUTHERN PORTIONS OF LAKE MICHIGAN IN THE 15-20 KT RANGE...AND A
FEW GUSTS TO 25 KTS ESPECIALLY EARLY SUNDAY...WILL MAKE FOR
MARGINAL SMALL CRAFT ADVISORY CONDITIONS ALONG THE WESTERN SHORE
OF THE LAKE SUNDAY MORNING PARTICULARLY BETWEEN DOWNTOWN CHICAGO
AND THE WISCONSIN BORDER. HAVE DECIDED TO GO AHEAD AND HOIST A
SMALL CRAFT ADVISORY HEADLINE FOR THAT PORTION OF THE NEARSHORE
WATERS THROUGH SUNDAY.
OTHERWISE...AS THE LOW DRIFTS ACROSS SOUTHERN ILLINOIS AND THE
LOWER OHIO VALLEY AND WEAKENS SUNDAY NIGHT AND MONDAY...WEAK HIGH
PRESSURE RIDGING WILL LINGER ACROSS THE WESTERN GREAT LAKES AREA.
AN AREA OF LOW PRESSURE MOVING ACROSS CENTRAL SASKATCHEWAN AND
NORTHERN ONTARIO WILL TRAIL A COLD FRONT ACROSS LAKE MICHIGAN
TOWARD MID-WEEK.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH RIP CURRENT RISK...ILZ006-ILZ014...10 AM SATURDAY TO 7 PM
SUNDAY.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO NORTHERLY IS UNTIL 7 PM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
111 AM CDT SAT SEP 1 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 06Z...
* NORTHEAST WINDS WITH GUSTS ABOVE 15 KTS TODAY BECOMING MORE
EASTERLY TONIGHT.
* TIMING OF RAIN AFFECTING TODAY/TONIGHT.
* POTENTIAL FOR MVFR CIG/VIS IF RAIN PERSISTS.
RATZER
//DISCUSSION...UPDATED 06Z...
TROPICAL DEPRESSION ISAAC WAS LOCATED OVER WEST CENTRAL MISSOURI
AT 05Z...WITH AN AREA OF MODERATE RAIN EXTENDING FROM FAR EASTERN
KANSAS ACROSS NORTHERN MISSOURI INTO MUCH OF CENTRAL/SOUTHERN IL.
ISAAC IS EXPECTED TO DRIFT VERY SLOWLY EAST INTO SOUTHERN IL
THROUGH SUNDAY MORNING. MAIN FORECAST QUESTION FOR THE TAFS IS
WHERE THE NORTHERN PERIPHERY OF THE RAIN ASSOCIATED WITH THIS
SYSTEM LAYS OUT IN RELATION TO THE TERMINAL LOCATIONS...AND THE
POTENTIAL FOR MVFR OR EVEN IFR CIG/VIS CONDITIONS IN THE AREAS
WHICH SEE PERSISTENT RAINFALL. 00Z HIGH RESOLUTION MODEL GUIDANCE
SUGGESTS THAT THE NORTHERN EDGE OF THE RAIN AREA WILL BE
APPROXIMATELY THROUGH THE INTERSTATE 88 CORRIDOR ACROSS NORTHERN
IL WITH AREAS TO THE NORTH LESS LIKELY TO SEE PERSISTENT RAIN AND
ASSOCIATED CIG/VIS REDUCTIONS. THIS MAKES FOR A TRICKY FORECAST
WITH TERMINALS IN/NEAR THE EXPECTED SHARP GRADIENT OF LITTLE/NO
RAIN TO THE NORTH AND CONSIDERABLE RAIN FARTHER TO THE SOUTH.
RFD WILL HAVE THE LOWEST LIKELIHOOD OF SEEING ANY PROLONGED PERIOD
OF RAIN AND LOWER CIG/VIS...WITH AN EXPECTATION THAT ORD/DPA WILL
PERHAPS SEE A FEW PERIODS OF LIGHTER RAIN AND GYY FARTHEST TO THE
SOUTH WOULD HAVE THE GREATEST THREAT OF LONGER DURATION RA/SHRA
AND ALSO LOWER CIG/VIS CONDITIONS. FOR NORTHERN TERMINALS...THE
GREATEST POTENTIAL FOR SOME RAIN TO AFFECT RFD/DPA/ORD/MDW WOULD
BE DURING THE AFTERNOON HOURS AS LOW/MID LEVEL MOISTURE CONVERGENCE
EXPANDS NORTHEASTWARD PER MODELS. HIGH-RES GUIDANCE INDICATES SOME
SHOWERS MAY AFFECT GYY AS EARLY AS THIS MORNING...WITH SOME WEAK
RADAR ECHOES ALREADY DEVELOPING SOUTH OF THE KANKAKEE RIVER VALLY
INTO INDIANA.
WINDS ARE EXPECTED TO REMAIN EAST-NORTHEAST THROUGH THE PERIOD AS
THE SURFACE LOW PRESSURE CIRCULATION MOVES SLOWLY ACROSS MISSOURI
AND DOWNSTATE IL. SOME GUSTS INTO THE 15-20 KT RANGE APPEAR
POSSIBLE MAINLY DURING THE DAY TODAY...THOUGH WEAK LOW LEVEL LAPSE
RATES SUGGEST GUSTS MAY BE SOMEWHAT SPORADIC.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WIND TRENDS. MEDIUM CONFIDENCE GUST SPEEDS.
* MEDIUM CONFIDENCE IN RAIN POTENTIAL AND CIG/VIS TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...OCCASIONAL RA. MVFR PSBL IFR CIGS.
MONDAY...CHC RA ISO TSRA. MVFR PSBL.
TUESDAY THROUGH WEDNESDAY...VFR. CHC SHRA/ISO TSRA W/MVFR CIGS.
THURSDAY...VFR.
BEACHLER
&&
.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 MARQUETTE MI
123 AM EDT SAT SEP 1 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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 122 AM EDT SAT SEP 1 2012
VFR CONDITIONS ARE EXPECTED AS DRY HIGH PRESSURE REMAINS IN CONTROL
THROUGH MUCH OF THE WEEKEND.
&&
.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...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
404 AM CDT Sat Sep 1 2012
.DISCUSSION...
Main Concern continues to be the remnants of TD Isaac and potential
for flooding. The GFS has been the best performer for the short term
as NAM and RAP were late in picking up the higher rainfall amounts in
the northwest quadrant of the circulation. This area...a deformation
zone of sorts...has seen upwards of 3.5 inches of rain over the last 12
hours or so. The Johnson County Kansas StormWatch observations show
this along with both the legacy and dual pol storm total
precipitation algorithms. The legacy precip algorithm has actually
underestimated by around a half an inch or so even though the Z-R
relationship was changed to tropical yesterday.
As the circulation continues to mainly wobble around Clinton MO we
should see continued rainfall over the above mentioned area...while
the extreme southern zones will have lesser amounts and probably not
much until the low begins to finally move east this afternoon.
Instability remains too weak to support convection so keeping that
out of the forecast for the short term.
The rain should taper off later this afternoon over the western zones
and by evening over the east. Another concern will be fog chances
overnight but thinking that enough stratus will linger such that will
keep fog out for now but day shift should review.
Sunday will see warming temperatures and drying conditions as 850MB
temperatures rebound and moisture from Isaac makes its way into the
Ohio Valley. Expect upper ridging over the area for Labor Day and Tuesday
so we will see continued highs in the 90s.
A front approaches from the north as the upper ridge is
flattened...courtesy of deepening upper trough over south central
Canada. Therefore we will see some chance of thunderstorms return
about mid week and cooler temperatures later in the week.
Adolphson
&&
.AVIATION...
For the 06Z TAFs...TD Isaac centered near Clinton Missouri continues to bring
IFR ceilings and MVFR visibilities in light to moderate rain over the
area. The current satellite...radar...and newest model guidance all
indicate that the northwest quadrant will be more active than previous
guidance suggested. Therefore...will continue prevailing conditions
until late in the morning when Isaac will finally begin to move
eastward. Expect a little lower ceilings for the afternoon through the
end of the period as saturated conditions continue near the surface.
Adolphson
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
350 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE COLD FRONT APPEARS TO BE HAVING A TOUGH TIME MAKING IT SOUTH
OF LAKE ERIE. DEWPOINTS HAVE SURGED INTO THE UPPER 60S AND LOWER
70S EVEN AS FAR EAST AS KERI. REGIONAL RADAR IS STARTING TO SHOW
SOME WEAK RETURNS JUST SOUTH OF THE AREA. THE LATEST GUIDANCE
INCLUDING THE HRRR SHOWS PRECIP DEVELOPING OVER THE SW 1/3 OF THE
AREA THIS MORNING AND CONTINUING INTO THE AFTERNOON. AM A LITTLE
CONCERNED THAT THE FRONT WILL NOT MAKE IT AS FAR SOUTH AS FORECAST
AND PRECIP WILL SPREAD FURTHER NORTH THAN EXPECTED. HAVE BUMPED
PRECIP CHANCES UP TO LIKELY IN THE FAR SOUTH AND ALL BUT THE FAR
NE CORNER OF OH AND NW PA WILL GET A PRECIP MENTION TODAY. PWAT
VALUES ARE EXPECTED TO CLIMB ABOVE TWO INCHES BY 00Z. CURRENTLY
NOT MUCH THUNDER BUT CANNOT RULE A FEW RUMBLES LATER TODAY. CLOUDS
SHOULD BE PRETTY THICK TODAY WHICH WILL HOLD TEMPS DOWN ABOUT 10
DEGREES FROM FRIDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
ONLY MINOR CHANCES TO THE SHORT TERM PERIOD PERIOD THIS MORNING.
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO GUIDANCE
TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
A COLD FRONT WILL PUSH SOUTH ACROSS LAKE ERIE THROUGH 09Z WITH WINDS
SHIFTING TO THE NORTH FOR AIRPORTS NEAR THE LAKE. MEANWHILE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC CONTINUE TO SPREAD NORTH INTO
OHIO. SOME BR IS POSSIBLE ALONG THE FRONT AS IT STALLS OVER NORTHERN
OHIO BETWEEN 09-13Z WITH VISIBILITIES ONLY DROPPING TO AROUND 4
MILES. OTHERWISE CHANCES OF SHOWERS AND THUNDERSTORMS WILL INCREASE
ACROSS WESTERN OHIO THROUGH THE AFTERNOON AND WILL CONTINUE TO CARRY
VCTS AS ENERGY SPIRALS AWAY FROM THE REMNANTS OF THE TROPICAL
SYSTEM. UNCERTAINTY REMAINS WITH RESPECT TO TIMING THUNDERSTORMS BUT
THINK CHANCES OF BRIEF HEAVY RAINFALL ARE PRETTY GOOD LATE THIS
AFTERNOON INTO THIS EVENING. DRIER AIR BEHIND THE FRONT SHOULD LIMIT
CHANCES OF PRECIPITATION ACROSS NE OHIO/NW PA WITH THE OVERALL
COVERAGE OF SHOWERS DECREASING WITH THE LOSS OF DIURNAL HEATING
AFTER 00Z. MVFR VISIBILITIES WILL BE POSSIBLE AGAIN AFTER 06Z WITH
HIGH LOW LEVEL MOISTURE ACROSS THE AREA.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
257 AM CDT SAT SEP 1 2012
.SHORT TERM...TODAY THROUGH TUESDAY
257 AM CDT SAT SEP 1 2012
THE MAIN FOCUS IN THE SHORT TERM IS WITH THE TEMPERATURES THIS
WEEKEND FOLLOWED BY THE PRECIPITATION CHANCES MONDAY INTO TUESDAY.
CURRENTLY...A BROAD RIDGE OF SURFACE HIGH PRESSURE SITS ACROSS
ONTARIO AND THE UPPER MISSISSIPPI RIVER VALLEY TO GREAT LAKES
REGION WHILE THE REMNANTS OF ISAAC TRACK NORTHEAST ACROSS
MISSOURI. CIRRUS HAS SPILLED NORTHWARD FROM ISAAC AND HAS HELPED
TO KEEP TEMPERATURES UP A BIT DESPITE THE CIRRUS BEING FAIRLY
THIN. WITH THE RIDGE FIRMLY IN PLACE ACROSS THE REGION...THE
REMNANTS OF ISAAC WILL HAVE A HARD TIME MAKING IT NORTH AND SHOULD
TAKE MORE OF AN EASTERLY TRACK OVER THE NEXT FEW DAYS. WITH THIS
INFLUENCE FROM THE RIDGE...ANY OF THE OUTER BANDS OF PRECIPITATION
SHOULD REMAIN TO THE SOUTHEAST OF THE FORECAST AREA INTO EASTERN
IOWA AND NORTHERN ILLINOIS. THE MAIN INFLUENCE FROM ISAAC MAY BE
ON THE TEMPERATURES ACROSS SOUTHERN WISCONSIN AND NORTHEAST IOWA
IF SOME DENSER MID TO UPPER LEVEL CLOUDS MOVE IN AND HELP TO
SUPPRESS TEMPERATURES A FEW DEGREES TODAY.
AS THE LOW LEVEL FLOW BECOMES MORE SOUTHERLY ON SUNDAY AHEAD OF
THE NEXT TROUGH/COLD FRONT...TEMPERATURES WILL CLIMB A TAD INTO
THE MID TO UPPER 80S. THIS FRONT WILL MOVE ACROSS MINNESOTA LATE
SUNDAY NIGHT INTO MONDAY MORNING AND SHOULD CROSS THE FORECAST
AREA DURING THE DAY MONDAY WITH THE 01.00Z NAM/GFS/ECMWF/GEM ALL
IN REASONABLE AGREEMENT WITH THIS TIMING. THIS FROPA TIMING WOULD
BE IDEAL FOR CONVECTIVE INITIATION DURING THE PEAK DIURNAL HEATING
HOURS OF THE DAY. HOWEVER...GUIDANCE ALSO SHOWS THE BETTER
500-300MB PV ADVECTION BEING UP TO THE NORTH ACROSS CENTRAL
MINNESOTA INTO NORTHERN WISCONSIN WITH NOT MUCH IN THE WAY OF LOW
LEVEL FRONTOGENESIS. 0-3KM MUCAPE DOES INCREASE TO BETWEEN
1000-2000 J/KG AHEAD OF THE FRONT AND IS UNCAPPED...SO ANY KIND OF
TRIGGER SHOULD AT LEAST PRODUCE SOME SCATTERED CONVECTION ALONG
THE FRONT. 0-3KM BULK WIND SHEAR DOES INCREASE TO AROUND 15-25KTS
JUST AHEAD OF THE FRONT IN WESTERN TO CENTRAL WISCONSIN AND BUFKIT
SOUNDINGS SHOW A DRY LAYER AROUND 650MB...SO SOME STRONGER WIND
GUSTS MAY OCCUR IF CONVECTION CAN DEVELOP. THUS...HAVE BUMPED UP
THE CHANCES FOR SHOWERS/STORMS MONDAY AFTERNOON.
AS THIS FRONT MOVES EAST AND CONTINUES TO WEAKEN...A BRIEF BREAK
IN THE FORM OF A SURFACE RIDGE WILL MOVE THROUGH MONDAY EVENING
BEFORE LOW LEVEL MOISTURE TRANSPORT INCREASES AHEAD OF THE NEXT
TROUGH. CONVECTION WILL LIKELY INITIATE IN EASTERN SOUTH DAKOTA
DURING THE AFTERNOON MONDAY AND REDEVELOP EAST ALONG THE NOSE OF
MOISTURE TRANSPORT INTO THE REGION OVERNIGHT INTO TUESDAY. THIS
FRONTAL PASSAGE...WHICH MAY NOT OCCUR UNTIL MID WEEK...WILL
PROVIDE THE BEST CHANCES FOR PRECIPITATION
.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
257 AM CDT SAT SEP 1 2012
THE BEST CHANCES FOR PRECIPITATION ACROSS THE REGION WILL COME
THROUGH MID WEEK AS A COLD FRONT PASSES. THIS TRAILING COLD FRONT
WILL BE THE MAIN FOCUS FOR RAIN CHANCES THOUGH THE INCREASING LOW
LEVEL MOISTURE TRANSPORT WILL BE NOSING UP INTO THE REGION AHEAD
OF TIME TUESDAY NIGHT INTO WEDNESDAY. 01.00Z GFS/ECMWF/GEM ARE ALL
IN FAIRLY GOOD AGREEMENT WITH BRINGING THIS COLD FRONT THROUGH
THE REGION THROUGH THE DAY WEDNESDAY WITH IT TO LAKE MICHIGAN BY
00Z THURSDAY. THIS FRONT WILL MARK THE START OF A PATTERN SHIFT
TO HAVING A MORE NORTHWESTERLY FLOW ALOFT THAT WILL USHER IN
COOLER AIR FROM CANADA. WHILE HIGH PRESSURE WILL MAINLY BE IN
PLACE ACROSS THE REGION...THERE HAVE BEEN SOME INDICATIONS OF
A SYSTEM DROPPING DOWN FROM SOUTH CENTRAL CANADA THURSDAY NIGHT
INTO FRIDAY...THOUGH THE TREND APPEARS TO BE TAKING THIS SYSTEM
MORE TO THE WEST AND MISSING THE REGION. CONFIDENCE IS NOT VERY
HIGH AT THIS POINT IN REGARD TO THESE PRECIPITATION CHANCES LATER
IN THE WEEK DUE TO THE AMOUNT OF CHANGES THAT SEEM TO COME WITH
EACH NEW RUN AND THIS SYSTEM.
&&
.AVIATION...THROUGH 06Z SUNDAY
1058 PM CDT FRI AUG 31 2012
WINDS HAVE GONE CALM AT KLSE WITH 01.01Z RAP BUFKIT SOUNDINGS
STILL SHOWING 30 KNOTS AT 015K FEET OVERNIGHT. THUS CONTINUED THE
MENTION OF LLWS AT KLSE. CIRRUS FROM THE REMNANTS OF ISAAC WILL
CONTINUE OVER THE TAF SITES THROUGH THE TAF PERIOD WITH VFR
CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
257 AM CDT SAT SEP 1 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1059 AM CDT SAT SEP 1 2012
.UPDATE...
Recent satellite observations indicate that Isaac is now
post-tropical, with the center of circulation now over Osceola, MO
and drifting southeast. Cloud tops within a broad deformation zone
have warmed considerably since 12Z as the system is merging with an
increasingly diffuse frontal zone, while the connection to the Gulf
is also being lost due to dry air entrainment over the Mid
Mississippi Valley.
All in all, the rain that has been anchored from southwest of Kansas
City northeastward toward Kirksville will gradually weaken in
intensity and shift slowly eastward this afternoon. Still an
effective washout for areas east of an Atchison KS to Grant City, MO
line, but additional amounts should average less than a third of an
inch, with the exception of areas along the Highway 69 and 71
corridors south of Kansas City where slightly stronger forcing will
persist for several more hours (perhaps another 0.50 to 0.75" here).
This rain could not have been more timely or beneficial, with most
portions of the forecast area seeing anywhere from 2 to 6" over the
past 24 hours. Of more importance is that hourly rainfall amounts
generally averaged 0.10 to 0.30" per hour through that duration. The
poor river/creek response thus far would indicate that a much much
higher than typical percentage of the rainfall has infiltrated the
soil as opposed to runoff, which should yield extensive benefits in
the short term.
While substantial moisture deficits still persist, the remnants of
Isaac have acted not only to deliver much needed rainfall, but
wholly alter the upper flow pattern across the US. In short, the
relocation of the upper ridge along the eastern seaboard and
suppression of its western counter part will allow an extensive
period of fast zonal flow to develop across the local region for the
next week. Within this cooler regime, baroclinity will strengthen
beneath the upper jet, supporting several potential rain chances
over the coming week as Pacific troughs now have a legitimate shot
of reaching the area.
Bookbinder
&&
.PREV DISCUSSION...
/ISSUED 404 AM CDT Sat Sep 1 2012/
Main Concern continues to be the remnants of TD Isaac and potential
for flooding. The GFS has been the best performer for the short term
as NAM and RAP were late in picking up the higher rainfall amounts in
the northwest quadrant of the circulation. This area...a deformation
zone of sorts...has seen upwards of 3.5 inches of rain over the last
12 hours or so. The Johnson County Kansas StormWatch observations
show this along with both the legacy and dual pol storm total
precipitation algorithms. The legacy precip algorithm has actually
underestimated by around a half an inch or so even though the Z-R
relationship was changed to tropical yesterday.
As the circulation continues to mainly wobble around Clinton MO we
should see continued rainfall over the above mentioned area...while
the extreme southern zones will have lesser amounts and probably not
much until the low begins to finally move east this afternoon.
Instability remains too weak to support convection so keeping that
out of the forecast for the short term.
The rain should taper off later this afternoon over the western zones
and by evening over the east. Another concern will be fog chances
overnight but thinking that enough stratus will linger such that will
keep fog out for now but day shift should review.
Sunday will see warming temperatures and drying conditions as 850MB
temperatures rebound and moisture from Isaac makes its way into the
Ohio Valley. Expect upper ridging over the area for Labor Day and
Tuesday so we will see continued highs in the 90s.
A front approaches from the north as the upper ridge is
flattened...courtesy of deepening upper trough over south central
Canada. Therefore we will see some chance of thunderstorms return
about mid week and cooler temperatures later in the week.
Adolphson
&&
.AVIATION...
For the 12Z TAFs...the remnants of Isaac are rotating across west
central Missouri this morning continuing to bring rain, occasionally
moderate, into the terminals. NAM bufr soundings and MOS guidance as
well as GFS LAMP and MOS guidance support IFR cigs this morning
lifting to MVFR this afternoon as rain comes to an end. MKC will
experience MVFR cigs/vis this morning as well. Rain will come to an
end at MKC this afternoon however MVFR cigs will prevail. STJ will
experience light rain through mid morning with occasional MVFR cigs
however rain will come to an end by mid morning with cigs becoming
VFR by early afternoon. Winds will be gusty around 20-25 knots out
of the north this morning diminishing to around 12kts this afternoon
as Isaac begins to pull off to the east.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
859 AM MDT SAT SEP 1 2012
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
UPDATE...ADJUSTED WEATHER ELEMENT AND POPS THIS MORNING BASED ON
CURRENT TRENDS. HRRR DOES BRING A FEW ISOLATED SHOWERS AND THUNDER
INTO THE REGION AGAIN THIS AFTERNOON. PROTON
SOUTHWEST FLOW ALOFT WILL PREVAIL OVER MONTANA TODAY AS UPPER LOW
OVER BRITISH COLUMBIA MOVES TO THE EAST. SURFACE LOW NEAR HAVRE AT
09Z WILL MOVE EAST ALONG THE MT/SASK BORDER TODAY. LEE SIDE TROUGH
EXTENDING SOUTHEAST FROM THE LOW WILL SLIDE THROUGH EASTERN
MONTANA THIS MORNING TURNING WINDS FROM EASTERLY TO SOUTH OR
SOUTHWEST. COLD FRONT CURRENTLY IN ALBERTA WILL FOLLOW THIS
EVENING TURNING WINDS TO THE WEST OR NORTHWEST. AIRMASS WILL
BECOME UNSTABLE ENOUGH FOR THUNDERSTORMS TODAY BUT LIMITED
MOISTURE WILL GENERALLY BE LIMITED TO MID AND HIGH LEVEL MONSOONAL
MOISTURE. EXPECT THUNDERSTORM COVERAGE TO BE ISOLATED. VERY DRY
LOW LEVEL AIR MAY ALLOW FOR SOME DOWNBURST WINDS IN ANY STORMS
THAT DEVELOP. LIGHTNING WITH LIMITED RAINFALL WILL MAKE WILDFIRES
A THREAT WITH ANY STORMS THAT OCCUR. WILL MAINTAIN RED FLAG
WARNING TODAY. THERMAL RIDGE WILL KEEP TEMPERATURES WARM BUT
CLOUD COVER MAY LIMIT TEMPERATURES SOMEWHAT TODAY.
THE COLD FRONT MOVES THROUGH EASTERN MONTANA THIS EVENING AND THE
SURFACE LOW BECOMES STACKED WITH THE UPPER LOW OVER ALBERTA AND
SASKATCHEWAN TONIGHT. AFTER THE FRONT MOVES THROUGH...A DRY SLOT
MOVES INTO MONTANA SHUTTING OFF ANY CHANCE FOR RAIN.
GUSTY WEST TO NORTHWEST WINDS WILL DEVELOP BEHIND THE FRONT SUNDAY
MORNING AS THE LOW REMAINS OVER SASKATCHEWAN. WHILE TEMPERATURES
WILL BE ABOUT 10 DEGREES COOLER THAN TODAY...RH WILL BE JUST AS
LOW POSSIBLY LOWER THAN TODAY WITH VERY DRY AIR EXPECTED OVER THE
AREA. EXPECT WINDS 15 TO 30 MPH WITH OCCASIONAL GUSTS UP TO 40
MPH BEHIND THIS FRONT. THE WINDS WILL DIMINISH SUNDAY EVENING WITH
THE LOSS OF DAYTIME HEATING. WILL CONTINUE RED FLAG WARNING
THROUGH SUNDAY. A LAKE WIND ADVISORY WILL LIKELY BE NEEDED FOR
FORT PECK LAKE ON SUNDAY. WILL WAIT UNTIL THE TIMING OF THE WINDS
COME INTO BETTER FOCUS BEFORE ISSUING THE ADVISORY.
THE LOW REMAINS OVER SASKATCHEWAN AND MANITOBA SUNDAY NIGHT AND
MONDAY BUT THE SURFACE GRADIENT RELAXES ALLOWING THE WINDS TO
DIMINISH. LABOR DAY WILL BE A MOSTLY SUNNY DAY WITH LIGHT WINDS
AND SLIGHTLY ABOVE NORMAL TEMPERATURES AFTER A COOL START. FORRESTER
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
TEMPERATURES BEGIN TO TREND COOLER DURING THE EXTENDED PERIOD
WHICH BEGINS MONDAY NIGHT. THE SLOW-MOVING CLOSED UPPER LOW THAT
HAS BEEN SPINNING OVER SOUTHERN BRITISH COLUMBIA WILL HAVE WORKED
ITS WAY INTO CENTRAL SASKATCHEWAN/MANITOBA BY 00Z TUESDAY. ITS
MAIN EFFECT MONDAY NIGHT WILL BE TO NUDGE THE STATIONARY BOUNDARY
SOUTH INTO NORTHEAST MONTANA.
THEN THE LOW SENDS A BACKDOOR COLD FRONT SOUTH TUESDAY. THE END
RESULT WILL BE MOST HIGH TEMPERATURES IN THE 70S OR 5F TO 10F
LOWER THAN NORMAL. TEMPERATURES WILL BE WARMER AROUND THE
YELLOWSTONE RIVER VALLEY WITH HIGHS IN THE LOWER 80S. MODELS
CONTINUE DRY BUT THE BACKDOOR FRONT COULD KNOCK OUT SOME LIGHT
RAIN SHOWERS. ANOTHER AFFECT OF THE FRONT WILL BE 20KT NW WINDS.
MIXING DOWN OF 700MB WINDS OF 30KTS WILL ADD WIND GUSTS. TUESDAY
NIGHT 700MB TEMPERATURES WITH CAA WILL RUN AROUND 0C ALONG THE
INTERNATIONAL BORDER FOR A COOLER NIGHT.
WEDNESDAY NIGHT AND BEYOND...THE GFS AND THE EC PICK UP ANOTHER
COOL SHORTWAVE DROPPING SOUTH FROM CANADA. MODELS SUGGEST A GOOD
SLUG OF MOISTURE WITH THIS WAVE...SOMETIME AROUND THURSDAY NIGHT
AFFECTING THE AREA. TEMPERATURES WILL REMAIN SLIGHTLY COOLER THAN
NORMAL INTO THE WEEKEND. A BUILDING RIDGE IN THE WEST WILL LIKELY
WARM TEMPERATURES AGAIN FOR THE FOLLOWING WEEK. SCT
&&
.AVIATION...
EXPECT MOSTLY VFR CONDITIONS FOR THIS TAF PERIOD...WITH SOME
INTERMITTENT MVFR VISIBILITIES POSSIBLE DUE TO HAZE/SMOKE FROM
WILDFIRES AROUND THE AREA. THIS SMOKE/HAZE IS NOT EXPECTED TO EXIT
THE AREA UNTIL A COLD FRONT PASSAGE LATER TODAY SHIFTS WIND AROUND
TO THE NORTHWEST. HIGH BASED THUNDERSTORMS ARE POSSIBLE ACROSS THE
REGION TODAY WHICH COULD PRODUCE STRONG ERRATIC WIND GUSTS.
BMICKELSON
&&
.FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED TODAY AND SUNDAY.
FOLLOWING POOR RH RECOVERY OVERNIGHT IN MANY AREAS (25 TO 50
PERCENT AS OF 3 AM MDT)...HUMIDITIES WILL FALL INTO THE TEENS
AGAIN THIS AFTERNOON ACROSS NORTHEAST MONTANA. WINDS WILL BE
MAINLY EAST TO SOUTHEAST AROUND 10 MPH THIS MORNING BECOMING
VARIABLE THIS AFTERNOON. A COLD FRONT IS EXPECTED THIS EVENING
WITH NORTHWEST WINDS 10 TO 20 MPH. CONDITIONS WILL BECOME UNSTABLE
BY AFTERNOON AND ISOLATED THUNDERSTORMS SHOULD DEVELOP. THESE
THUNDERSTORMS WILL BECOME GOOD LIGHTNING PRODUCERS ACROSS EASTERN
MONTANA. ANY FIRES STARTED BY LIGHTNING WILL BE IMPACTED BY THIS
SUDDEN SHIFT AND CHANGE IN WIND SPEED AND STRENGTH. WEST TO
NORTHWEST WINDS WILL INCREASE TO 15 TO 30 MPH SUNDAY MORNING WITH
HUMIDITIES ONCE AGAIN FALLING INTO THE TEENS SUNDAY AFTERNOON.
FORRESTER
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT SUNDAY FOR MTZ120-122-134>137.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1006 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR ADJUSTMENTS MADE TO THE FORECAST. AREAS SOUTH OF US 30 HAVE
THE BEST SHOT AT SCATTERED/ ON AND OFF SHOWERS/TS TODAY. FRONT HAS
SLIPPED SOUTH OF THE LAKESHORE AND HAVE USED ITS CURRENT POSITION
TO DELINEATE THE BETTER PRECIP CHANCES TO THE SOUTH. HRRR SHOWING
WIDESPREAD PRECIP SOUTH OF A LINE FROM KTOL TO KYNG BY LATE THIS
AFTERNOON. FRONT IS AS FAR SOUTH AS IT IS GOING TO GET. WILL KEEP
AN EYE ON INSTABILITY FOR THIS AFTERNOON WITH THIS WIDESPREAD BKN
TO OVC SKY WANTING TO LIMIT IT. TEMPS WILL ALSO BE IN THE 80 TO
85 RANGE...BUT IT WILL BE HUMID ESPECIALLY ACROSS THE CENTRAL AND
SOUTHWEST COUNTIES. ACROSS NW PA...MAY GET SOME DRIER AIR PUSH
DOWN WITH THE HIGH NORTH OF THE LAKES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO
GUIDANCE TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF ISAAC WILL CONTINUE TO
INCREASE FROM THE SOUTHWEST TODAY. A LEADING BAND OF SHOWERS WILL
CONTINUE TO IMPACT FDY OVER THE NEXT HOUR OR SO BEFORE WEAKENING
AS IT APPROACHES MFD. ADDITIONAL BANDS OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO APPROACH FDY/TOL/MFD THIS AFTERNOON
WITH A MOIST AND UNSTABLE AIRMASS IN PLACE WITH THE MOST LIKELY
TIMING BETWEEN 18-22. ANY THUNDERSTORMS THAT IMPACT THE AIRPORTS
THIS AFTERNOON WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. THERE
IS A LESSER CHANCE OF CONVECTION DEVELOPING FURTHER EAST AS DRIER
AIR TRIES TO PUSH SOUTH BEHIND A WEAK FRONT. SOME DECREASE IN THE
COVERAGE OF SHOWERS AND THUNDERSTORMS IS EXPECTED OVERNIGHT BEFORE
THE DEEPER MOISTURE APPROACHES ON SUNDAY. HIGH LOW LEVEL MOISTURE
MAY RESULT IN MVFR VISIBILITIES AFTER 06Z TONIGHT.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA/OUDEMAN
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION...CORRECTED
NWS WILMINGTON OH
935 AM EDT SAT SEP 1 2012
.SYNOPSIS...
THE REMNANTS OF ISAAC WILL SLOWLY MEANDER EAST TOWARDS THE AREA
THROUGH THE HOLIDAY WEEKEND RESULTING IN UNSETTLED CONDITIONS. THE
LOW WILL FINALLY MOVE EAST OF THE REGION ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REMNANT TROPICAL DEPRESSION ISAAC /BECOMING EXTRATROPICAL AS WE
SPEAK/ CONTINUES TO SPIN NWRD ACRS WRN MO. PRIMARY BAND OF RAIN
EAST OF CYCLONE IS EJECTING EWRD ACRS WRN IND. NW TO SE ORIENTED
BAND OF SHRA/TSRA OVER CNTL OH IS PUTTING DOWN LOCALLY HEAVY
RAINFALL AMOUNTS EAST OF CMH AND IS BEING WATCHED CLOSELY FOR
SHORT TERM RUNOFF ISSUES /FLASH FLOOD WARNINGS/.
01.12Z KILN RAOB SAMPLED A VERY JUICY TROPOSPHERE WITH PW AT 2.02
INCHES WHICH IS A LITTLE OVER 2 STD ABOVE CLIMO. MOIST ADIABATIC
LAPSE RATES IN THE MID LEVELS...TALL SKINNY CAPES /1500 J/KG/ FOR
PARCELS LIFTED JUST ABOVE THE SFC. WARM CLOUD DEPTHS AROUND 3.6KM
AREN/T AS HIGH AS ANTICIPATED...BUT STILL A VERY EFFICIENT RAINFALL
ENVIRONMENT.
MORNING/RECENT RAP RUNS HAVE A DEFINED 850MB CONVERGENCE ZONE
SUPPORTING THE CNTL OH CONVECTION AND PERSISTS THIS CONVERGENCE
INTO THE NOON HOUR. THIS IS NEAR THE TOP OF THE MID/UPPER LEVEL
S/W RIDGE DOWNSTREAM OF ISAAC...THE IDEAL BREEDING GROUND FOR
REGENERATIVE CONVECTION. THUS...GIVEN AMBIENT AIRMASS AND HIGH
REFLECTIVITIES REMAINING BELOW THE FREEZING LEVEL /WARM RAIN
PROCESSES/ WILL NEED TO WATCH CLOSELY FOR FLASH FLOOD POTENTIAL
EAST/SOUTHEAST OF CMH IN NEXT COUPLE OF HOURS. RAP/NAM INDICATE AS TD
ISAAC PLODS SLOWLY EAST TODAY...THAT DEEPER SLY FLOW SHOULD PUSH THIS
CONVERGENCE MAX NWRD AS IT BREAKS DOWN...SO HOPING THAT IS THE
CASE.
OTHERWISE...WITH DEEP MOISTURE AND LOW CONVECTIVE TEMPS EXPECT DIM
SUN THROUGH THICK CIRRUS SHOULD ALLOW WEAKLY FORCED/DIURNALLY
DRIVEN DOWNPOURS OVER MUCH OF THE AREA THROUGH THE DAY. ALREADY
SEEING THIS OVER NRN KY/SRN IND...SO MAINTAINED THE HIGH AFTN RAIN
CHANCES. NOT TO MENTION THE BAND OF RAIN ENCROACHING INTO WRN/CNTL
IND...WHICH TIME LAGGED RAP/NAM ENSEMBLE SHOWING HAS A HIGH
PROBABILITY OF ENTERING WRN OH AFTER 1 OR 2 PM. A VERY MUGGY DAY
THAT WILL NOT BE A COMPLETE WASHOUT...BUT WILL HAVE A FAIR SHARE
OF RADAR ACTIVITY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
REMNANTS OF ISAAC CENTERED TO THE WEST WILL EVER SO SLOWLY MAKES
ITS WAY TOWARDS THE FORECAST AREA THROUGH THE PERIOD. THERE IS
ABUNDANT MOISTURE IN PLACE AHEAD OF THIS SYSTEM. SO ONLY WEAK
FORCING WILL BE NEEDED TO GENERATE PRECIPITATION.
IT APPEARS THAT AN OLD EAST-WEST BOUNDARY NEAR THE NORTHERN ZONES
MAY SERVE AS A PRIMARY FOCUS TONIGHT. THEN THE FOCUS WILL SHIFT TO
IMPULSES ROTATING AROUND THE MAIN SYSTEM. AS THE STACKED LOW GETS
CLOSER THE SHOWERS SHOULD PROGRESS FROM OFF AND ON TO MORE
PERSISTENT LATE SUNDAY INTO SUNDAY NIGHT. THE UPPER SYSTEM WILL
TRANSITION TO AN OPEN WAVE ON MONDAY AND THAT ADDS UNCERTAINTY TO
THE SYSTEM EVOLUTION. SO BACKED OFF ON POPS SLIGHTLY AT THAT TIME.
BUT IT IS CERTAINLY QUITE POSSIBLE THAT SHOWERS WILL STILL BE
RATHER WIDESPREAD MONDAY WITH GUIDANCE SUGGESTING THAT SOUTHERN
COUNTIES WOULD GET MORE ON THE HOLIDAY.
STILL THINKING THAT RAINFALL AMOUNTS FOR THE ENTIRE EVENT WILL
MAINLY RANGE FROM 1 TO 3 INCHES. THIS SHOULD BE A BENEFICIAL RAIN
FOR THE MOST PART. BUT CANNOT RULE OUT LOCALIZED FLASH FLOODING
FROM ANY STRONGER CONVECTION THAT MAY DEVELOP AS THESE WOULD BE
VERY EFFICIENT RAIN PRODUCING STORMS.
SHOULD NOT BE A LOT OF VARIATION IN TEMPERATURES WITH A DIURNAL
RANGE OF 10 DEGREES OR LESS. WENT ABOVE MOS FOR LOWS AND AT OR
SLIGHTLY BELOW COOLER NAM MOS FOR HIGHS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
COULD STILL SEE SOME SHOWERS AND THUNDERSTORMS MONDAY NIGHT INTO
TUESDAY AS THE LOW CONTINUES TO TRANSITION AND MOVE OFF TO THE
EAST OF THE REGION. FLOW WILL BE FAIRLY ZONAL THROUGH THE REST OF
THE WEEK. A SHORT WAVE WILL PUSH A COLD FRONT ACROSS THE AREA
WEDNESDAY OR WEDNESDAY NIGHT. THEN HIGH PRESSURE WILL BUILD IN
WITH DRIER AND COOLER CONDITIONS FOR THE LATTER PART OF THE WEEK.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
BANDS OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP TODAY IN
OUTER BANDS AHEAD OF ISAAC AND DIURNALLY ESPECIALLY IN THE
SOUTHWEST FCST AREA AS THE OUTGOING RIDGE CONTINUES TO PUSH OUT
AND BREAK DOWN. THE DAY CERTAINLY WONT BE A WASH OUT...BUT MORE
LIKE AREAS OF SHOWERS. NOT EXPECTING HEAVY PRECIP RESULTING IN
MVFR CIGS NOR VSBYS...THOUGH POSSIBLE IN THE ISOLATED BRIEF
THUNDERSTORMS TODAY. AFTER SOME DIMINISHING NEAR 00Z...THE HEAVIER
PRECIPITATION FROM ISAAC APPROACHES AFTER 00Z...SO BETTER CHANCE
FOR MVFR CIGS/VSBYS IN MODERATE RAINFALL.
.OUTLOOK...MVFR CEILINGS AND VISIBILITIES...WITH LOCAL IFR
VISIBILITIES...WILL BE POSSIBLE WITHIN SHOWERS AND EMBEDDED
THUNDERSTORMS THROUGH TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BINAU
SHORT TERM...
LONG TERM...
AVIATION...JDR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
751 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS EXPECTED SOME SHOWERS AND STORMS HAVE BEGUN TO DEVELOP WEST OF
KFDY. THIS ACTIVITY SHOULD MOVE INTO THE WEST END OF THE AREA
SHORTLY. OTHER STORMS ARE EXPECTED TO DEVELOP AND MOVE ACROSS THE
SW 1/3 OF THE AREA THIS MORNING. HAVE DECIDED TO USE SCATTERED
WORDING FOR THAT AREA. LATEST HRRR SHOWING WIDESPREAD PRECIP SOUTH
OF A LINE FROM KTOL TO KYNG BY LATE THIS AFTERNOON.
PREVIOUS...THE COLD FRONT APPEARS TO BE HAVING A TOUGH TIME MAKING IT SOUTH
OF LAKE ERIE. DEWPOINTS HAVE SURGED INTO THE UPPER 60S AND LOWER
70S EVEN AS FAR EAST AS KERI. REGIONAL RADAR IS STARTING TO SHOW
SOME WEAK RETURNS JUST SOUTH OF THE AREA. THE LATEST GUIDANCE
INCLUDING THE HRRR SHOWS PRECIP DEVELOPING OVER THE SW 1/3 OF THE
AREA THIS MORNING AND CONTINUING INTO THE AFTERNOON. AM A LITTLE
CONCERNED THAT THE FRONT WILL NOT MAKE IT AS FAR SOUTH AS FORECAST
AND PRECIP WILL SPREAD FURTHER NORTH THAN EXPECTED. HAVE BUMPED
PRECIP CHANCES UP TO LIKELY IN THE FAR SOUTH AND ALL BUT THE FAR
NE CORNER OF OH AND NW PA WILL GET A PRECIP MENTION TODAY. PWAT
VALUES ARE EXPECTED TO CLIMB ABOVE TWO INCHES BY 00Z. CURRENTLY
NOT MUCH THUNDER BUT CANNOT RULE A FEW RUMBLES LATER TODAY. CLOUDS
SHOULD BE PRETTY THICK TODAY WHICH WILL HOLD TEMPS DOWN ABOUT 10
DEGREES FROM FRIDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
ONLY MINOR CHANCES TO THE SHORT TERM PERIOD PERIOD THIS MORNING.
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO GUIDANCE
TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
MOISTURE ASSOCIATED WITH THE REMNANTS OF ISAAC WILL CONTINUE TO
INCREASE FROM THE SOUTHWEST TODAY. A LEADING BAND OF SHOWERS WILL
CONTINUE TO IMPACT FDY OVER THE NEXT HOUR OR SO BEFORE WEAKENING
AS IT APPROACHES MFD. ADDITIONAL BANDS OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO APPROACH FDY/TOL/MFD THIS AFTERNOON
WITH A MOIST AND UNSTABLE AIRMASS IN PLACE WITH THE MOST LIKELY
TIMING BETWEEN 18-22. ANY THUNDERSTORMS THAT IMPACT THE AIRPORTS
THIS AFTERNOON WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. THERE
IS A LESSER CHANCE OF CONVECTION DEVELOPING FURTHER EAST AS DRIER
AIR TRIES TO PUSH SOUTH BEHIND A WEAK FRONT. SOME DECREASE IN THE
COVERAGE OF SHOWERS AND THUNDERSTORMS IS EXPECTED OVERNIGHT BEFORE
THE DEEPER MOISTURE APPROACHES ON SUNDAY. HIGH LOW LEVEL MOISTURE
MAY RESULT IN MVFR VISIBILITIES AFTER 06Z TONIGHT.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
628 AM EDT SAT SEP 1 2012
.SYNOPSIS...
A WEAK COLD FRONT ALONG THE SOUTH SHORE OF LAKE ERIE IS EXPECTED
TO MOVE SOUTH TO CENTRAL OHIO LATER TODAY AND THEN STALL. THE
REMNANTS OF ISAAC OVER MISSOURI THIS MORNING WILL MOVE SLOWLY EAST
ALONG THE FRONT AND ACROSS THE UPPER OHIO VALLEY ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS EXPECTED SOME SHOWERS AND STORMS HAVE BEGUN TO DEVELOP WEST OF
KFDY. THIS ACTIVITY SHOULD MOVE INTO THE WEST END OF THE AREA
SHORTLY. OTHER STORMS ARE EXPECTED TO DEVELOP AND MOVE ACROSS THE
SW 1/3 OF THE AREA THIS MORNING. HAVE DECIDED TO USE SCATTERED
WORDING FOR THAT AREA. LATEST HRRR SHOWING WIDESPREAD PRECIP SOUTH
OF A LINE FROM KTOL TO KYNG BY LATE THIS AFTERNOON.
PREVIOUS...THE COLD FRONT APPEARS TO BE HAVING A TOUGH TIME MAKING IT SOUTH
OF LAKE ERIE. DEWPOINTS HAVE SURGED INTO THE UPPER 60S AND LOWER
70S EVEN AS FAR EAST AS KERI. REGIONAL RADAR IS STARTING TO SHOW
SOME WEAK RETURNS JUST SOUTH OF THE AREA. THE LATEST GUIDANCE
INCLUDING THE HRRR SHOWS PRECIP DEVELOPING OVER THE SW 1/3 OF THE
AREA THIS MORNING AND CONTINUING INTO THE AFTERNOON. AM A LITTLE
CONCERNED THAT THE FRONT WILL NOT MAKE IT AS FAR SOUTH AS FORECAST
AND PRECIP WILL SPREAD FURTHER NORTH THAN EXPECTED. HAVE BUMPED
PRECIP CHANCES UP TO LIKELY IN THE FAR SOUTH AND ALL BUT THE FAR
NE CORNER OF OH AND NW PA WILL GET A PRECIP MENTION TODAY. PWAT
VALUES ARE EXPECTED TO CLIMB ABOVE TWO INCHES BY 00Z. CURRENTLY
NOT MUCH THUNDER BUT CANNOT RULE A FEW RUMBLES LATER TODAY. CLOUDS
SHOULD BE PRETTY THICK TODAY WHICH WILL HOLD TEMPS DOWN ABOUT 10
DEGREES FROM FRIDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
ONLY MINOR CHANCES TO THE SHORT TERM PERIOD PERIOD THIS MORNING.
MODELS SIMILAR IN TRACKING WHAT`S LEFT OF ISAAC ACROSS THE REGION
ON MONDAY. EXPECT MOISTURE TO SURGE NORTH INTO THE AREA AHEAD OF
THE LOW. PWAT VALUES WILL BE AT OR ABOVE 2 INCHES THE NEXT SEVERAL
DAYS SO THE POTENTIAL EXISTS FOR LOCALLY HEAVY RAINFALL. ABOUT THE
SW 1/2 OF THE AREA CAN EXPECT BETWEEN 1 AND 2 INCHES OF RAINFALL
WITH LOCALLY HEAVIER AMOUNTS POSSIBLE WHERE THE STRONGER BANDS
PERSIST. PRECIP TOTALS WILL DROP OFF QUICKLY TO THE NE. GIVEN
RECENT DRY SPELL AND LOW WATER LEVELS SEE NO NEED FOR ANY FLOOD
HEADLINES. THE PRECIP MAY DROP OFF SOME SUNDAY NIGHT BUT BY
DAYBREAK MONDAY WILL AGAIN NEED LIKELY WORDING ALL AREAS. WILL
CONTINUE TO MENTION THUNDER AS WELL GIVEN UNSTABLE AIRMASS. THE
SURFACE LOW WILL BE NE OF THE AREA BY DAYBREAK TUESDAY AND EXPECT
PRECIP TO QUICKLY DIMINISH FROM WEST TO THE EAST DURING THE DAY.
WEAK COLD AIR ADVECTION BEHIND THE LOW MAY BE ENOUGH TO KICK OFF A
FEW LIGHT SHOWERS INTO TUESDAY NIGHT. HAVE STAYED CLOSE TO GUIDANCE
TEMPS AGAIN TODAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL PUSH EAST ACROSS THE
GREAT LAKES REGION FROM WEDNESDAY INTO THURSDAY. SOUTHERLY FLOW
AHEAD OF THIS FEATURE ON WEDNESDAY WILL HELP TEMPERATURES WARM INTO
THE MID AND UPPER 80S. WILL HOLD ONTO A LOW CHANCE OF
SHOWERS/THUNDERSTORMS AHEAD OF THE TROUGH ACROSS NW OHIO ON
WEDNESDAY...EXPANDING EAST ACROSS THE FORECAST AREA ON THURSDAY. A
COLD FRONT PUSHES SOUTH ACROSS THE AREA ON THURSDAY NIGHT WITH DRY
NORTHWESTERLY FLOW AND BUILDING HIGH PRESSURE FOR THE END OF THE
WEEK. TEMPERATURES WILL DROP BACK TO NEAR OR BELOW NORMAL VALUES.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
A COLD FRONT WILL PUSH SOUTH ACROSS LAKE ERIE THROUGH 09Z WITH WINDS
SHIFTING TO THE NORTH FOR AIRPORTS NEAR THE LAKE. MEANWHILE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC CONTINUE TO SPREAD NORTH INTO
OHIO. SOME BR IS POSSIBLE ALONG THE FRONT AS IT STALLS OVER NORTHERN
OHIO BETWEEN 09-13Z WITH VISIBILITIES ONLY DROPPING TO AROUND 4
MILES. OTHERWISE CHANCES OF SHOWERS AND THUNDERSTORMS WILL INCREASE
ACROSS WESTERN OHIO THROUGH THE AFTERNOON AND WILL CONTINUE TO CARRY
VCTS AS ENERGY SPIRALS AWAY FROM THE REMNANTS OF THE TROPICAL
SYSTEM. UNCERTAINTY REMAINS WITH RESPECT TO TIMING THUNDERSTORMS BUT
THINK CHANCES OF BRIEF HEAVY RAINFALL ARE PRETTY GOOD LATE THIS
AFTERNOON INTO THIS EVENING. DRIER AIR BEHIND THE FRONT SHOULD LIMIT
CHANCES OF PRECIPITATION ACROSS NE OHIO/NW PA WITH THE OVERALL
COVERAGE OF SHOWERS DECREASING WITH THE LOSS OF DIURNAL HEATING
AFTER 00Z. MVFR VISIBILITIES WILL BE POSSIBLE AGAIN AFTER 06Z WITH
HIGH LOW LEVEL MOISTURE ACROSS THE AREA.
.OUTLOOK...NON VFR POSSIBLE SUNDAY THROUGH TUESDAY FROM THE MOISTURE
ASSOCIATED WITH THE REMNANTS OF ISAAC AND AN APPROACHING COLD
FRONT.
&&
.MARINE...
EASTERLY WINDS WILL CONTINUE ON LAKE ERIE THROUGH THE LABOR DAY
WEEKEND AS LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF ISAAC SLOWLY
MOVES EAST ACROSS THE OHIO VALLY. WINDS AND WAVES WILL BE RELATIVELY
LIGHT THROUGH THE PERIOD WITH CHANCES OF RAIN INCREASING THROUGH
MONDAY. SCATTERED SHOWERS OR THUNDERSTORMS WILL BE CONFINED TO AREAS
FROM CLEVELAND WESTWARD TODAY...EXPANDING EAST ACROSS THE LAKE ON
SUNDAY AND BECOMING MORE WIDESPREAD ON MONDAY. ANY SHOWERS OR
THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
RAINFALL.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...KUBINA
SHORT TERM...KUBINA
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
831 AM CDT SAT SEP 1 2012
.UPDATE...
MOIST CONDITIONS IN PLACE. LATEST OHX SOUNDING SHOWED CONVECTIVE
TEMPS OF 80 DEGREES F WITH A SFC DEW POINT OF 72F. CURRENT TEMPS
ARE IN THE MID TO UPPER 70S. CAP TO AGAIN BE DISMISSED BY 18Z
TODAY AS TEMPS WARM INTO THE 80S. OMEGA FIELDS SEEM TO BE SOMEWHAT
NEUTRAL SO THAT CONVECTION DEVELOPMENT SHOULD STAY ON THE SCT
SIDE BUT SUNSHINE SHOULD REMAIN RATHER LIMITED.
FOR THE FCST...ONLY PARAMETER THAT WILL NEED A TWEAK APPEARS TO BE
THE MAX TEMPS FOR TODAY. HRRR IS IN LINE WITH THE CONVECTIVE
DEVELOPMENT BY AFTERNOON AND THE 18Z PROG TEMPS ARE IN THE LOWER
TO MID 80S. WILL THEREFORE MAKE A SLIGHT DOWNWARD TWEAK TO THE
HIGH TEMPS. THIS MAY OR MAY NOT CHANGE THE ZONE WORDING BUT I WILL
STILL REISSUE. UPDATE OUT SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 651 AM CDT SAT SEP 1 2012/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...REMNANTS OF FORMER HURRICANE ISAAC CONTINUE TO MOVE
EVER-SO-SLOWLY EASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY TODAY
AND TONIGHT, WITH SOUTHERLY FLOW ON THE EAST SIDE KEEPING
OUR ATMOSPHERE CHOCKED FULL OF MOISTURE.
EXPECT A PERIOD OF MVFR CIGS THROUGH 16Z, THEN VFR FOR THE
REMAINDER OF THE DAYLIGHT HOURS. EXPECT SCATTERED THUNDERSTORMS TO
DEVELOP DURING THE AFTERNOON, WITH A CHANCE FOR THUNDERSTORMS TO
IMPACT AREA TERMINALS, ALONG WITH BRIEF PERIODS OF MVFR AND
POSSIBLY IFR CONDITIONS, ESPECIALLY AT CKV AND BNA.
EXPECT SHOWERS AND THUNDERSTORMS TO DIMINISH AT BNA AND CSV AFTER
SUNSET. HOWEVER, SCATTERED TO NUMEROUS SHOWERS ARE FORECAST TO
RE-DEVELOP IN THE CKV AREA AFTER 06Z, AS DEEPEST MOISTURE FROM
ISAAC STARTS TO NOSE INTO NORTHWESTERN MIDDLE TENNESSEE.
SURFACE WINDS WILL BE SOUTHERLY, WITH AFTERNOON GUSTS AT BNA AND
CKV TO 20 KTS.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1100 AM MDT SAT SEP 1 2012
.UPDATED...FIRST AND SECOND PERIODS
&&
.SHORT TERM...NECESSARY ADJUSTMENTS TO CURRRENT FCST...ALBEIT
MINOR...WILL INVOLVE FIRST AND SECOND PERIOD SKY COVER...PRECIP
PROBABILITIES...MAXIMUM TEMPERATURES AND WINDS MAINLY FOR THE
PLAINS. MAIN FOCUS TODAY WILL BE THE DEVELOPING CRITICAL WILDLAND
FIRE DANGER CONDITIONS ON THE PLAINS. A RED FLAG WARNING IS SLATED
TO START AT 1700Z/1100 MDT TODAY. HOWEVER LATEST 15 AND 30 MINUTE
SFC OBSERVATIONS WERE ALREADY INDICATING SOUTHERLY WIND GUSTS IN
THE 20-28KT RANGE AT A FEW LOCATIONS IN NORTHERN LINCOLN AND
WASHINGTON COUNTIES. WHILE RELATIVE HUMIDITY VALUES WERE STILL
GENERALLY ABOVE 20 PCT..BUT FALLING. THE 1700Z START TIME FOR THE
RED FLAG WARNING STILL LOOKS GOOD.
OTHER ATTENTION IS THE BAND OF CONVECTION DEVELOPING OVER WESTERN
COLORADO AT THE MOMENT. NOT SEEING ANY LIGHTNING STRIKES WITH IT
YET...BUT ONLY A MATTER OF TIME. DEVELOPMENT ATTRIBUTED IN PART TO
WEAK MID-LEVEL QUASI-GEOSTROPHIC ASCENT/LIFT AHEAD OF A WEAK
SHORTWAVE TROUGH MOVED ALONG BY PREVAILING SOUTHWEST FLOW ALOFT.
RUC INDICATES TO THE TROUGH AXIS JUST THE EAST OF THE
UTAH/COLORADO BORDER AT THIS HOUR. AT ITS CURRENT SPEED SHOULD
SEE THIS DISTURBANCE AND THE CONVECTION IT GENERATES MOVING OVER
OUR NORTH CENTRAL MTNS/NRN FRONT RANGE FOOTHILLS IN THE NEXT HOUR
OR SO. MOST IF NOT ALL OF THIS CONVECTION IS EXPECTED TO REMAIN
OVER THE HIGHER TERRAIN...HOWEVER HIGH BASED MOSTLY DRY STORMS
MOVING JUST OFF THE FOOTHILLS COULD GENERATE SOME PRETTY GUSTY
OUTFLOW WINDS BASED ON MODEL INVERTED-V SOUNDINGS ON THE PLAINS.
MAY SEE GUSTY OUTFLOW WINDS SPREADING OUT ACROSS PORTIONS OF THE
I-25 URBAN CORRIDOR AFTER 21Z TODAY WITH GUSTS POTENTIALLY TO
AROUND 30KT. COULD SEE THESE GUST BOUNDARIES CONTINUING TO MOVE
EAST CRISS-CROSSING THE PLAINS THROUGH THE EVENING...WHICH WOULD
PRETTY MUCH CUT DOWN THE GUSTY SOUTHERLY SFC WINDS OUT THERE THIS
AFTERNOON. AS FOR TEMPERATURES...I-25 URBAN CORRIDOR TEMPS MAY
STRUGGLE TO REACH THE MID 90S TODAY...BUT IN AREAS FARTHER EAST
COVERED BY THE RED FLAG WARNING READINGS ARE ALREADY IN THE
MID/UPPER 80S. SO NUDGED HIGH TEMPERATURES UP 1-3F OUT THERE.
.AVIATION...VFR CONDITIONS ARE ANTICIPATED AT DENVER AREA
AIRPORTS NOW THROUGH 12Z/SUNDAY. HOWEVER GUSTY OUTFLOW WINDS FROM
MOSTLY DRY HIGH BASED FORMING STORMS OVER THE FOOTHILLS AFTER 21Z
THIS AFTERNOON COULD PRODUCE GUSTS ON THE ORDER OF 25-35KT IN THE
DENVER AREA. THE CHANCE FOR THESE WIND SPEEDS OCCURRING AT APA
AND DIA IS NOT AS GREAT AS THAT FOR BJC CLOSER TO THE FOOTHILLS.
&&
.FIRE WEATHER...RED FLAG WARNING WILL GO INTO EFFECT AT 17Z/11 AM
MDT THIS MORNING AND WILL REMAIN IN EFFECT UNTIL 19Z/7 PM MDT
THIS EVENING FOR A LARGE PORTION OF NORTHEAST COLORADO. GUSTY
SOUTHERLY WINDS HAVE ALREADY DEVELOPED AT A NUMBER OF LOCATIONS
IN WASHINGTON AND NORTHERN LINCOLN COUNTIES AND BASED ON THE
LATEST MODEL DATA SHOULD BECOME MORE WIDESPREAD WITHIN THE NEXT
1-2 HOURS. AT THIS HOUR RELATIVE HUMIDITY VALUES STILL GENERALLY
ABOVE 20 PERCENT...BUT THEY SHOULD FALL WITHIN WARNING CRITERIA
IN THE NEXT HOUR OR TWO AT MOST LOCATIONS WITHIN THE WARNING
ACCORDING TO THE HRRR...RUC AND NAM.
&&
.HYDROLOGY...PROBABLY THE ONLY REAL CONCERN TODAY WILL BE BRIEF
LIGHT TO MODERATE RAINFALL PRODUCED BY WIDELY SCATTERED STORMS
MOVING OFF THE CONTINENTAL DIVIDE AFTER 1 PM MDT TODAY. ONE OR
TWO OF THESE STORMS MAY DRIFT OVER A FRONT RANGE BURN SCAR
POSSIBLY DEPOSITING UP TO A QUARTER INCH OF RAIN IN UNDER 25
MINUTES. HOWEVER ODDS OF THIS OCCURRING TODAY APPEAR LOW AS WE
MAY SEE MORE IN THE WAY OF GUSTY OUTFLOW WINDS AND CG LIGHTNING
WITH THESE HIGH BASED STORMS.
&&
.PREV DISCUSSION... /ISSUED 311 AM MDT SAT SEP 1 2012/
SHORT TERM...SAME OLD STORY AS THE UPPER LEVEL RIDGE CONTINUES
OVER THE AREA WITH SSW FLOW ALOFT. SUBTROPICAL MOISTURE WILL
CONTINUE TO AFFECT THE MTNS WITH SCT AFTN TSTMS WHILE THE HIGHER
VALLEYS AND FOOTHILLS SEE WDLY SCT STORMS. OVER NERN CO IT WILL
REMAIN HOT AND DRY ALTHOUGH OUTFLOW BOUNDARIES FROM HIGHER TERRAIN
CONVECTION MAY TRIGGER A FEW STORMS MAINLY WEST OF I-25. AFTN
HIGHS WILL BE IN THE 90S ACROSS NERN CO WITH HIGH FIRE DANGER.
GUSTY SOUTH WINDS WILL BE HIGH ENOUGH FOR RED FLAG CONDITIONS OVER
THE PLAINS. FOR TONIGHT SOME LINGERING SHOWERS/TSTMS WILL CONTINUE
OVER THE HIGHER TERRAIN THRU THE EARLY EVENING HOURS WITH MOST
ACTIVITY ENDING BY MIDNIGHT.
LONG TERM...FAIRLY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED
OVER THE CWA SUNDAY THROUGH MONDAY NIGHT. THE SYNOPTIC SCALE ENERGY
IS WEAK SUNDAY THROUGH MONDAY NIGHT. THE LOW LEVEL PRESSURE AND
WIND FIELDS SHOW A WEAK COLD FRONT TO MOVE INTO THE PLAINS ON
SUNDAY. WEAK UPSLOPE IS PROGGED FOR THE PLAINS INTO SUNDAY
EVENING. ON MONDAY...THE GRADIENT IS WEAK SO NORMAL DIURNAL WIND
PATTERNS SHOULD PREVAIL. FOR MOISTURE...THEN IS SOME PROGGED
..MAINLY IN THE UPPER AND MID LEVELS ON SUNDAY INTO MONDAY
EVENING. DEW POINT PROGGS ARE MAINLY IN THE 40S F OVER THE PLAINS
..WITH 30S F IN THE MOUNTAINS ON SUNDAY...AND A TAD LOWER ON
MONDAY. THE GFS IS A BIT HIGHER THAN THE NAM. PRECIPITABLE WATER
VALUES ARE IN HE 0.90-1.00 INCH RANGE ON SUNDAY...THEN THE 0.75-0.85
INCH RANGE ON MONDAY. THERE IS A TAD OF CAPE PROGGED OVER THE
MOUNTAINS LATE DAY SUNDAY...NOTHING FOR THE PLAINS. BY LATE DAY
MONDAY...THE NAM ONLY HAS LIMITED CAPE OVER THE MOUNTAINS...WHILE
THE GFS HAS A TAD OVER THE FAR EAST. THE QPF FIELDS HAVE A TAD OF
MEASURABLE RAINFALL PROGGED OVER THE MOUNTAINS LATE DAY SUNDAY.
THERE IS EVEN LESS INDICATED FOR MONDAY. FOR POPS...WILL GO WITH
"CHANCE"S IN THE MOUNTAINS SUNDAY AFTERNOON AND EVENING...NOTHING
FOR THE PLAINS. FOR LATE DAY MONDAY...WILL GO WITH 20% IN THE
MOUNTAINS...10%S ELSEWHERE. CONCERNING FIRE WEATHER...WILL GO WITH
NO HIGHLIGHTS SUNDAY FOR THE PLAINS BECAUSE THE WINDS DON`T SEEM TO
BE AN ISSUE...AND RELATIVE HUMIDITIES WILL BE MARGINAL. IT WILL BE A
BIT COOLER SUNDAY EVEN THOUGH MOISTURE IS NOT GREAT. FOR
TEMPERATURES...SUNDAY`S HIGHS SHOULD BE 1.0-2.5 C COOLER THAN
SATURDAY`S HIGHS. MONDAY`S HIGHS MAY BE A TAD WARMER THAN
SUNDAY`S. FOR THE LATER DAYS...TUESDAY THROUGH FRIDAY...MODELS HAVE
A PRETTY FLAT UPPER RIDGE CENTERED TO THE SOUTH OF COLORADO WITH
MAINLY ZONAL FLOW ALOFT TUESDAY INTO THURSDAY NIGHT. ON FRIDAY...
BOTH THE GFS AND ECMWF SHOW A VIGOROUS UPPER TROUGH MOVING
SOUTHEASTWARD TO OUR NORTH AND NORTHEAST. THE FLOW ALOFT BECOMES
NORTHWESTERLY ON FRIDAY...AND BOTH MODELS SHOW A SIGNIFICANT COLD
FRONT TO MOVE IN THE CWA. THE GFS AND ECMWF ALSO SHOW A WEAKER COLD
FRONT TO MOVE IN ON WEDNESDAY. MOISTURE IS SPARSE FOR ALL THE
DAYS.
AVIATION...WINDS HAVE REMAINED SOUTH EARLY THIS MORNING AND
SHOULD BE SSW THRU LATE MORNING. BY 18Z LATEST HRRR SHOWS A WK
DENVER CYCLONE NR THE AIRPORT WITH LIGHT NLY WINDS DEVELOPING THRU
21Z. AFTER 21Z THE HRRR SHOWS AN OUTFLOW BNDRY MOVING ACROSS THE
AIRPORT FM CONVECTION OVER THE FOOTHILLS WITH WINDS BECOMING WNW.
COULD BRIEFLY SEE SOME WIND GUSTS TO 25 MPH OR SO WITH THIS BNDRY.
FOR NOW WILL NOT MENTION ANY TSTM ACTIVITY AT DIA. BY EARLY EVENING
WILL SHIFT WINDS BACK TO THE SW AND KEEP THEM THAT WAY OVERNIGHT.
A WK CDFNT WILL MOVE INTO THE AREA AFTER 12Z SUN WITH WINDS
BECOMING NLY BY 15Z.
HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE IN
THE BURN AREAS THIS AFTERNOON WITH RAINFALL AMOUNTS AROUND A
QUARTER INCH OR LESS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BAKER/RPK
LONG TERM....RJK
AVIATION...BAKER/RPK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
130 PM EDT SAT SEP 1 2012
.SYNOPSIS...
SEASONABLE TEMPERATURES ARE ON TAP FOR THE HOLIDAY WEEKEND WITH HIGH
PRESSURE GENERALLY IN CONTROL. DRY WEATHER SHOULD DOMINATE THROUGH
LABOR DAY...OTHER THAN A SPOT SHOWER OR TWO. RAIN IS LIKELY TUESDAY
INTO WEDNESDAY AS A COLD FRONT WITH MOISTURE FROM ISAAC/S REMNANTS
MOVES INTO THE REGION. A SECOND COLD FRONT MOVES THROUGH ON
THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1 PM UPDATE...
A FEW SHOWERS HAVE POPPED UP OVER SRN NH AND NW MA IN A WEAK
CONVERGENCE REGION BETWEEN THE NW FLOW IN VT AND NY AND THE E TO
NE FLOW MOVING OVER SRN NEW ENGLAND. RUC DATA DOES SUGGEST THAT
THERE IS SOME VERY WEAK AND VERY LOW LVL INSTABILITY AROUND THE BL
THAT THESE SHOWERS MAY FEED ON THANKS TO THE LIFT PROVIDED BY THE
CONVERGENCE. HAVE KEPT MOSTLY SLIGHT CHANCE POPS W OF WORCESTER
INTO SRN NH AS THE COVERAGE SHOULD GENERALLY REMAIN ISOLATED
THROUGH THE DAY AS DRIER AIR BEGINS TO BUILD OVER FROM THE NW WITH
HIGH PRES. BUT THE UPPER LVL TROF WILL BE MOVING OVER INTO THE
EVENING...WHICH MAY PROLONG THIS CHANCE FOR PRECIP...SO HAVE KEPT
THE SLIGHT CHANCE POPS INTO THE EARLY HOURS OF THE OVERNIGHT.
PREVIOUS DISCUSSION...
THE MAIN STORY WILL BE THE COOLER WEATHER TO START THE WEEKEND
BEHIND THE FRONT...UNDER PARTLY TO MOSTLY SUNNY SKIES. ONSHORE
FLOW SHOULD HOLD HIGH TEMPERATURES IN THE MIDDLE TO UPPER 70S
ALONG THE IMMEDIATE COAST/HIGH TERRAIN...WITH MAINLY LOWER 80S
ELSEWHERE.
A MOISTURE STARVED SHORTWAVE WILL BE DROPPING DOWN IN NORTHWEST FLOW
ALOFT. THERE MAY BE ENOUGH MARGINAL INSTABILITY FOR A BRIEF SPOT
SHOWER OR TWO ACROSS THE INTERIOR THIS AFTERNOON. CONFIDENCE ON
WHETHER ANYTHING CAN DEVELOP IS LOW AND IF IT DOES AREAL
COVERAGE/DURATION WOULD BE QUITE LIMITED. THEREFORE...JUST INCLUDED
A SLIGHT CHANCE POP IN THIS REGION.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
LIGHT SOUTHEAST FLOW AT THE SURFACE AND A SHORTWAVE ALOFT MAY BE
ENOUGH TO SPAWN A FEW ISOLATED SHOWERS ACROSS THE INTERIOR.
AGAIN...AREAL COVERAGE/DURATION SHOULD BE LIMITED GIVEN DRY MID
LEVEL AIR...SO WILL JUST INCLUDE A SLIGHT CHANCE POP IN THIS
REGION. LOW TEMPERATURES WILL MAINLY BE IN THE 50S TO NEAR 60. MAY
SEE A BIT OF PATCHY GROUND FOG IN THE TYPICALLY PRONE
LOCATIONS...BUT NOTHING WIDESPREAD IS EXPECTED.
SUNDAY...
ANOTHER MOISTURE STARVED SHORTWAVE WILL BE DROPPING DOWN IN
NORTHWEST FLOW ALOFT. WHILE MUCH OF THE DAY WILL BE DRY AT A GIVE
LOCATION...THERE PROBABLY WILL BE AT LEAST A FEW HIT AND MISS
SHOWERS AROUND THE REGION. WILL RUN WITH SOME 20 TO 30 POPS TO
COVER THIS POTENTIAL...BUT ANY RAINFALL AMOUNTS WILL BE QUITE
LIGHT. HIGH TEMPERATURES WILL BE IN THE 70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
* RAIN CHANCES INCREASE TUESDAY INTO WEDNESDAY
* ANOTHER COLD FRONT MOVES THROUGH THURSDAY
OVERVIEW...
THE MODELS ARE IN DECENT AGREEMENT THROUGH MUCH OF THE LONG TERM.
THERE ARE SOME SUBTLE DIFFERENCES THROUGHOUT BUT NOTHING THAT
CREATES A LARGE SHIFT IN SENSIBLE WEATHER. FAIRLY QUIET WEATHER
EXPECTED SUNDAY NIGHT AND MONDAY. THE NEXT CHANCE FOR PRECIP WILL
BE TUESDAY AND WEDNESDAY WITH A FRONTAL SYSTEM...AND MOISTURE FROM
ISAACS REMNANTS. THEN ANOTHER COLD FRONT MOVES THROUGH THURSDAY.
HIGH PRESSURE RETURNS FRIDAY.
SUNDAY NIGHT THROUGH MONDAY...HIGH PRESSURE BUILDS INTO SOUTHERN NEW
ENGLAND. TEMPS WILL BE NEAR NORMAL.
MONDAY NIGHT THROUGH WEDNESDAY...CONFIDENCE IS INCREASING IN THIS
PORTION OF THE EXTENDED FORECAST. ALL MODELS HAVE BEEN CONSISTENTLY
INDICATING THE ARRIVAL OF A LOW PRESSURE SYSTEM FROM THE MIDWEST
ALONG WITH MOISTURE FROM THE REMNANTS OF ISAAC. SOUTHERLY FLOW
AHEAD OF THIS COLD FRONT MONDAY NIGHT WILL INCREASE WARM AIR
ADVECTION AND MOISTURE ACROSS THE AREA...BRINGING SHOWERS INTO
WESTERN NEW ENGLAND MONDAY NIGHT. INSTABILITY IS LIMITED SO DO NOT
EXPECT ANY THUNDER MONDAY NIGHT. FOR TUESDAY THROUGH WEDNESDAY...
COPIOUS AMOUNTS OF MOISTURE FROM ISAACS REMNANTS WILL BE MOVING INTO
THE REGION. MODELS HAVE BETWEEN 1 INCH AND 2 AND A HALF INCHES OF
QPF ACROSS MUCH OF SOUTHERN NEW ENGLAND. WHILE IT IS TOO EARLY TO
KNOW EXACTLY HOW THIS WILL EVOLVE...WITH TROPICAL REMNANTS
INVOLVED...IT IS VERY LIKELY THAT THERE WILL BE LOCALLY HEAVY
RAINFALL ACROSS SOUTHERN NEW ENGLAND. HAVE KEPT LOW END LIKELY POPS
IN FOR THE TIME BEING...THESE WILL LIKELY BE RAISED OVER THE NEXT
FEW DAYS.
THURSDAY...ANOTHER COLD FRONT WILL MOVE THROUGH SOUTHERN NEW
ENGLAND. MODELS DIFFER ON WHETHER THIS WILL BE A DRY COLD FRONT OR
IF THERE WILL BE SHOWERS POSSIBLE. WITH THAT UNCERTAINTY IN MIND
WILL KEEP SLIGHT CHANCE TO LOW END CHANCE POPS IN FOR THE TIME
BEING.
FRIDAY...HIGH PRESSURE BUILDS IN BEHIND THE FRONT WITH DRY...
PLEASANT WEATHER EXPECTED.
&&
.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...HIGH CONFIDENCE.
MAINLY VFR THROUGH SUN NIGHT. MAY HAVE SOME VERY BRIEF MVFR
CONDITIONS IN ISOLATED SHOWERS IN THE W AND SRN NH INTO THE
OVERNIGHT HOURS TONIGHT. MAY BE SOME MVFR/IFR GROUND FOG AT
TYPICALLY PRONE TERMINALS TONIGHT. NE WINDS GRADUALLY DIMINISH
TODAY...BECOME LIGHT AND VRB TONIGHT INTO THE DAY SUN.
KBOS TERMINAL...HIGH CONFIDENCE IN VFR TODAY INTO SUN.
KBDL TERMINAL...HIGH CONFIDENCE IN VFR TODAY INTO SUN.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT THROUGH MONDAY...MODERATE TO HIGH CONFIDENCE IN
MOSTLY VFR CONDITIONS. PATCHY MVFR/IFR FOG POSSIBLE SOME NIGHTS AT
THE TYPICALLY PRONE AIRPORTS.
MONDAY NIGHT THROUGH WEDNESDAY...MODERATE TO HIGH CONFIDENCE.
MVFR/IFR CONDITIONS EXPECTED IN SHOWERS/RAIN.
&&
.MARINE...
FORECAST CONFIDENCE MODERATE TO HIGH THROUGH SUNDAY AFTERNOON.
COOL ADVECTION BEHIND THE COLD FRONT WILL YIELD NORTHEAST WIND GUSTS
OF 20 TO 25 KNOTS TODAY. THIS SHOULD RESULT IN SEAS BUILDING TO
AROUND 5 FEET ACROSS THE OUTER-WATERS. THEREFORE...WILL HAVE SCA
HEADLINES FOR SOME OF OUR WATERS TODAY FOR THESE MARGINAL CONDITIONS.
WINDS WILL DIMINISH THIS EVENING...BUT 5 FOOT SEAS WILL LINGER
ACROSS THE SOUTHERN OUTER-WATERS INTO TONIGHT AND POSSIBLY EVEN INTO
EARLY SUNDAY. OTHERWISE...WEAKER PRESSURE GRADIENT SHOULD GENERALLY
KEEP WINDS AND SEAS BELOW SCA THRESHOLDS MOST OF SUNDAY.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE BUILDS OVER THE WATERS
SUNDAY NIGHT AND MONDAY...KEEPING WINDS AND SEAS BELOW SCA
CRITERIA. WINDS AND SEAS INCREASE AGAIN MONDAY NIGHT THROUGH
WEDNESDAY AS A COLD FRONT APPROACHES THE WATERS. RAIN AND FOG ARE
ALSO POSSIBLE DURING THIS TIME FRAME.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
ANZ231>234-250.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...FRANK/RLG
NEAR TERM...FRANK/DOODY
SHORT TERM...FRANK
LONG TERM...RLG
AVIATION...DOODY/RLG
MARINE...FRANK/RLG
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
409 PM EDT SAT SEP 1 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 407 PM EDT SAT SEP 1 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE PACIFIC NW
WITH DOWNSTREAM RIDGE EXTENDING N INTO SCNTRL CANADA. REMNANT OF
ISAAC IS OVER THE MID MISSISSIPPI VALLEY. DOWNSTREAM OF THE RIDGE
AXIS AND WELL N OF ISAAC REMNANT...TRANQUIL WEATHER DOMINATES UPPER
MI THIS AFTN UNDER ABUNDANT SUNSHINE. THE TRANQUIL WEATHER WILL
PERSIST THRU THE SHORT TERM AS THE UPSTREAM RIDGE SHIFTS E...
REACHING THE GREAT LAKES SUN.
AS SFC HIGH OVER LAKE SUPERIOR DRIFTS E TONIGHT...LIGHT RETURN FLOW
WILL GET UNDERWAY...ESPECIALLY W. SHOULD STILL BE A GOOD RADIATIONAL
COOLING NIGHT UNDER MAINLY CLEAR SKIES...THOUGH NOT AS GOOD AS LAST
NIGHT DUE TO DEVELOPING LIGHT RETURN FLOW AND INCREASING COLUMN
MOISTURE. FAVORED THE LOW SIDE OF AVBL GUIDANCE WHICH HAS
TRADITIONAL COLD SPOTS DROPPING TO THE LWR 40S. THERE IS SOME
CONCERN THAT DEVELOPING LOW-LEVEL E TO SE FLOW ACROSS NRN LAKE MI
COULD LEAD TO STRATUS/FOG DEVELOPMENT OVER THE SCNTRL FCST AREA AS
MARINE MODIFIED HIGHER DWPTS ADVECT INLAND/UPSLOPE INTO THE
RADIATIONALLY COOLED BOUNDARY LAYER INLAND. AT THIS TIME...IT
APPEARS SFC WINDS WILL BE BACKED ENOUGH OVER SCNTRL UPPER MI TO
PREVENT MUCH INLAND ADVECTION OF MOISTURE. WILL BE SOMETHING TO
MONITOR OVERNIGHT.
DRY AIR MASS WILL LINGER THRU SUN AFTN...PROVIDING ONE MORE DRY/WARM
EARLY SEPT DAY. PER FCST SOUNDINGS...STRENGTHENING CAP SUN WILL
LIMIT MIXING DEPTH COMPARED TO RECENT DAYS. MIXING TO 850MB YIELDS
MAX TEMPS MOSTLY IN THE LWR 80S AWAY FROM LAKE MODERATION. ALTHOUGH
VERY DRY AIR LINGERS ALOFT (CENTERED AROUND 800MB)...SFC DWPTS
SHOULDN`T FALL AS MUCH AS IN RECENT AFTNS SINCE MIXING WON`T TAP AS
SIGNIFICANTLY INTO THE DRIER ALOFT. STILL...WITH DWPTS FALLING
TOWARD 50F IN THE AFTN...RH WILL BOTTOM OUT AS LOW AS 30-35PCT.
ALTHOUGH PRES GRADIENT WILL BEGIN TO TIGHTEN BTWN DEPARTING SFC HIGH
AND APPROACHING COLD FRONT OVER THE PLAINS...SFC RIDGING EXTENDING
BACK TO UPPER MI WILL HELP TO SLOW THE INCREASE IN WINDS...AND THIS
WILL HELP TO EASE FIRE WX CONCERNS SUN.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 407 PM EDT SAT SEP 1 2012
MUCH OF OUR WEATHER FOR THIS LONG TERM PERIOD WILL BE HEAVILY
INFLUENCED BY THE 500MB LOW CURRENTLY SPINNING ALONG THE BRITISH
COLUMBIA/ALBERTA BORDER...WHICH WILL SET UP HOUSE OVER
ONTARIO/HUDSON BAY/QUEBEC FROM WEDNESDAY THROUGH AT LEAST NEXT
SATURDAY.
SUNDAY NIGHT...
WILL BEGIN SUNDAY NIGHT WITH THE WRAPPED UP SFC LOW SET UP ACROSS N
SASKATCHEWAN...WITH THE COLD FRONT/OCCLUDED FRONT PUSHING SSE
THROUGH C MANITOBA AND DOWN THROUGH THE RED RIVER VALLEY OF THE N.
LIGHT S WINDS WILL BE COMMON...KEEPING TEMPS FROM FALLING INTO THE
LOW 50S...WITH THE WARMEST TEMPS IN THE 60S NEAR THE GREAT LAKES.
MONDAY...
TIMING OF THE COLD FRONT HAS SLOWED DOWN A BIT...NO LONGER OVER W
LAKE SUPERIOR BY 12Z MONDAY...BUT JUST W. THE LOW ITSELF WILL ONLY
BE ABLE TO PUSH TO W CENTRAL MANITOBA WHERE IT WILL BECOME NEARLY
STATIONARY...SLOWLY EDGING TO NE MANITOBA BY 00Z WEDNESDAY.
MEANWHILE ACROSS UPPER MICHIGAN...UNIDIRECTIONAL WINDS AND AFTERNOON
HEATING COMBINED WITH THE WEAKENING COLD FRONT WILL ALLOW FOR SHOWER
AND THUNDERSTORM DEVELOPMENT. THE MAIN THREAT WILL BE STRONG GUSTY
WINDS DURING THE AFTERNOON...AND EARLY EVENING HOURS FAR E. MUCH OF
THE AREA IS IN A SPC SLIGHT RISK AREA FOR DAY 3/MONDAY. ADDED THE
POTENTIAL TO THE HWO...BUT IT LOOKS MODERATE AT THIS TIME...GIVEN
0-6KM BULK SHEAR VALUES AOB 35KTS...WITH HIGHER VALUES REMAINING W
AND S OF THE CWA. WHILE THE OUTPUT FROM THE 12Z GFS IS NOT AS
EXCITED ABOUT THE POTENTIAL...THE NAM DOES HAVE 0-3KM SHR VALUES OF
150-200M2/S2 OVER FAR W UPPER MI BY 18Z...AND OVER MUCH OF W UPPER
MI BY 21Z. THE BRUNT OF THE STORMS/PRECIP SHOULD BE TRACKING E
15-20KTS.
TUESDAY THROUGH WEDNESDAY...
WARMED UP HIGH TEMPS FOR TUESDAY ROUGHLY 5 DEGREES...WITH THE
HIGHEST VALUES S CENTRAL AND E. THIS AREA SHOULD HAVE THE LEAST
CHANCE OF SEEING PRECIP AND LIGHT SSW WINDS. ANOTHER SURGE OF COOLER
AIR WILL BE TO OUR W...WITH THE SECONDARY COLD FRONT SET UP OVER MN
TUESDAY AFTERNOON. IT SHOULD MOVE ACROSS W UPPER MI TUESDAY EVENING.
SPED UP THE EXIT OF TS IN THE GRIDS FOR WEDNESDAY.
THURSDAY THROUGH SATURDAY...
COOL NW FLOW WITH 850MB TEMPS FALLING TO 6-9C...ASSISTED ADDITIONAL
WEAK SHORTWAVES ALOFT...WILL LIKELY RESULT IN SPRINKLES/DRIZZLE
ACROSS THE FAVORED UPSLOPE LOCATIONS NEAR LAKE SUPERIOR AND E. THESE
LOW POP/LOW QFP SHOWERS WILL CONTINUE OFF AND OFF THROUGH FRIDAY AS
850MB TEMPS COOL A COUPLE MORE DEGREES...AND THE MAIN 500MB TROUGH
SINKS ACROSS THE CWA. MODEL GUIDANCE IS IN FAIRLY GOOD SHAPE...WRT
THE 12Z ISSUANCES...THROUGH FRIDAY MORNING. AFTER THAT TIME THE 12Z
GFS EJECTS THE MAIN 500MB LOW THAT HAD BEEN SITTING NEAR JAMES BAY
AT 12Z FRIDAY QUICKLY NORTHEASTWARD. THE ECMWF ON THE OTHER HAND
JUST HAS THE LOW SLOWLY SINK SE TO QUEBEC. EVEN SO...HIGH PRESSURE
SHOULD STILL BE ABLE TO PUSH ACROSS THE UPPER GREAT LAKES
SATURDAY...THE GFS IS JUST A BIT QUICKER. LAKE BREEZES DOMINATING AT
LEAST LAKE MI BY THE EARLY AFTERNOON HOURS. W FLOW MAY BE MORE
STEADY N ACROSS LAKE SUPERIOR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 134 PM EDT SAT SEP 1 2012
VFR CONDITIONS WILL CONTINUE AT KIWD/KCMX/KSAW THRU SUNDAY AS DRY
HIGH PRESSURE REMAINS OVER/NEAR THE UPPER GREAT LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EDT SAT SEP 1 2012
UNDER SFC HIGH PRES...WINDS ACROSS LAKE SUPERIOR WILL REMAIN LIGHT
TONIGHT...MOSTLY UNDER 15KT. AS THE HIGH SHIFTS TO THE E SUN...E TO
SE WINDS WILL BEGIN TO INCREASE...REACHING UP TO 20KT OVER FAR WRN
LAKE SUPERIOR AND PORTIONS OF CNTRL LAKE SUPERIOR IN THE AFTN. AS A
COLD FRONT APPROACHES SUN NIGHT...SOUTHERLY WINDS MAY GUST AS HIGH
AS 25KT AT HIGHER OBS PLATFORMS...ESPECIALLY OVER THE E HALF OF THE
LAKE. PRES GRADIENT THEN SLACKENS WITH PASSING COLD FRONT MON...
RESULTING IN WINDS DIMINISHING BACK TO UNDER 15KT MON INTO TUE. NEXT
COLD FRONT PASSING WED WILL BRING AN INCREASE IN W TO NW WINDS TO
AROUND 20KT...MAYBE HIGHER...LATER WED INTO THU.
&&
.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 ST LOUIS MO
351 PM CDT SAT SEP 1 2012
.SHORT TERM...
ISSUED AT 347 PM CDT SAT SEP 1 2012
(TONIGHT AND SUNDAY)
MAIN CONCERN CONTINUES TO BE SEVERE POTENTIAL AND LOCALLY HEAVY
RAINFALL. THIN LINE OF STORMS EXTENDING FROM CENTRAL ILLINOIS
SOUTHWESTWARD INTO SOUTHEAST MISSOURI WILL CONTINUE TO MOVE NORTH
NORTHEAST THE NEXT FEW HOURS. THE RAP IS SHOWING PERSISTENT LOW
LEVEL MOISTURE CONVERGENCE AS A VORT MAX MOVES AROUND THE SOUTH SIDE
OF THE UPPER LOW NOW MEANDERING OVER MISSOURI. OBJECTIVE ANALYSIS
OVER THIS SAME AREA DEPICTS SBCAPES 1000-1500 J/KG WHICH SHOULD
DIMINISH THROUGH THE EVENING. LIKE YESTERDAY...THERE IS LITTLE DEEP
LAYER SHEAR WITH THIS SYSTEM...SO ANY SEVERE WEATHER WILL BE SHORT
LIVED. MAIN CONCERN IS WHERE THE TORNADO WATCH IS IN EFFECT FOR
SHORT LIVED TORNADOES WHERE 0-1KM SRH VALUES ARE CURRENTLY IN THE
200-250 J/KG RANGE.
SEVERE THREAT WILL WANE THROUGH THE EVENING AS THE INSTABILITY
WEAKENS. WILL CONTINUE TO SEE AREAS OF RAIN THIS EVENING INTO THE
OVERNIGHT. WILL BEGIN TO SLOWLY LOWER POPS FROM WEST TO EAST
TONIGHT AS THE UPPER LOW MOVES EAST. THERE MAY BE SOME LOCALLY
HEAVY RAINFALL WITH THE THUNDERSTORMS INTO EARLY EVENING THAT
COULD CAUSE SOME LOCALIZED FLOODING ALONG AREA CREEKS AND LOW
LYING AREAS. ADDITIONAL RAINFALL TOTALS WILL RANGE FROM A COUPLE
OF TENTHS OVER CENTRAL MISSOURI TO OVER AN INCH OVER SOUTH CENTRAL
ILLINOIS.
BRITT
&&
.LONG TERM...
ISSUED AT 347 PM CDT SAT SEP 1 2012
(SUNDAY NIGHT THROUGH NEXT SATURDAY)
FOLLOWED THE GFS WHICH HAS THE UPPER LOW CONTINUING TO MOVE EAST ON
SUNDAY AND SUNDAY NIGHT. STILL HAVE CHANCE OR LIKELY POPS GOING
SUNDAY WITH CHANCE POPS OVER THE SOUTHEAST HALF THE CWA ON SUNDAY
EVENING. THEREAFTER...STILL LOOKS FAIRLY ACTIVE FOR EARLY
SEPTEMBER. GLOBAL MODELS ARE SHOWING ZONAL FLOW OVER THE NORTHERN
HALF OF THE NATION WHICH WILL BRING A SHORTWAVE ACROSS THE AREA
TUESDAY INTO WEDNESDAY. THERE IS SOME DIFFERENCES BETWEEN THE
GFS/ECMWF LATER IN THE WEEK WITH HOW QUICKLY A TROUGH WILL DIG INTO
THE CENTRAL U.S.. FOR NOW WILL HAVE A CHANCE OF SHOWERS/
THUNDERSTORMS GOING LATE WEEK INTO EARLY NEXT WEEKEND.
BRITT
&&
.AVIATION...
ISSUED AT 1238 PM CDT SAT SEP 1 2012
LOW PRESSURE SYSTEM IS LOCATED JUST SW OF KCOU AT 1700Z WITH MVFR
CONDITIONS NEARLY DOMINATING MOST OF THE REGION. A SMALLER AREA OF
IFR IS LOCATED MORE CONCENTRATED AROUND THE LOW PRESSURE CENTER.
EXPECTING THE LOW TO MOVE EASTWARD THROUGH THE PERIOD AND BE
LOCATED NEARLY OVER ST. LOUIS AT 06Z AND IN SE IL BY 18Z SUNDAY.
SCATTERED SHOWERY LIGHT PRECIPITATION IS EXPECTED THROUGH TONIGHT
WITH THE MAIN THREAT OF THUNDERSTORMS FROM ST LOUIS EASTWARD FROM
THE AFTERNOON INTO THE EVENING. LOWER CIGS WILL SPREAD FROM WEST
TO EAST IN ASSOCIATION WITH THE LOW...AND EXPECTING WIDESPREAD IFR
CONDITIONS TO EVENTUALLY BLANKET THE AREA TONIGHT. CIGS HEIGHTS
WILL GRADUALLY IMPROVE ON SUNDAY FROM WEST TO EAST FROM MID-
MORNING INTO THE AFTERNOON.
SPECIFICS FOR KSTL...
MVFR CONDITIONS EXPECTED THROUGH THE EARLY EVENING WITH BANDS OF
LIGHT SHOWERS. AFTER 20Z WE ARE EXPECTING ADDITIONAL THUNDERSTORMS
AND AM NOT SURE IF THEY WILL FORM OVER ST. LOUIS OR FURTHER EAST.
AT THIS TIME KEPT WITH A VCTS MENTION. IFR CIGS SHOULD SETTLE INTO
THE AREA TONIGHT AS THE LOW PRESSURE SYSTEM APPROACHES AND MOVES
OVER KSTL. CIGS HEIGHTS WILL IMPROVE ON SUNDAY AFTERNOON INTO THE
MVFR FLIGHT CAT AS THE LOW MOVES EAST AND TOWARDS THE OHIO VALLEY.
GLASS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1246 PM CDT SAT SEP 1 2012
...UPDATED AVIATION DISCUSSION...
.UPDATE...
Recent satellite observations indicate that Isaac is now
post-tropical, with the center of circulation now over Osceola, MO
and drifting southeast. Cloud tops within a broad deformation zone
have warmed considerably since 12Z as the system is merging with an
increasingly diffuse frontal zone, while the connection to the Gulf
is also being lost due to dry air entrainment over the Mid
Mississippi Valley.
All in all, the rain that has been anchored from southwest of Kansas
City northeastward toward Kirksville will gradually weaken in
intensity and shift slowly eastward this afternoon. Still an
effective washout for areas east of an Atchison KS to Grant City, MO
line, but additional amounts should average less than a third of an
inch, with the exception of areas along the Highway 69 and 71
corridors south of Kansas City where slightly stronger forcing will
persist for several more hours (perhaps another 0.50 to 0.75" here).
This rain could not have been more timely or beneficial, with most
portions of the forecast area seeing anywhere from 2 to 6" over the
past 24 hours. Of more importance is that hourly rainfall amounts
generally averaged 0.10 to 0.30" per hour through that duration. The
poor river/creek response thus far would indicate that a much much
higher than typical percentage of the rainfall has infiltrated the
soil as opposed to runoff, which should yield extensive benefits in
the short term.
While substantial moisture deficits still persist, the remnants of
Isaac have acted not only to deliver much needed rainfall, but
wholly alter the upper flow pattern across the US. In short, the
relocation of the upper ridge along the eastern seaboard and
suppression of its western counter part will allow an extensive
period of fast zonal flow to develop across the local region for the
next week. Within this cooler regime, baroclinity will strengthen
beneath the upper jet, supporting several potential rain chances
over the coming week as Pacific troughs now have a legitimate shot
of reaching the area.
Bookbinder
&&
.PREV DISCUSSION...
/ISSUED 404 AM CDT Sat Sep 1 2012/
Main Concern continues to be the remnants of TD Isaac and potential
for flooding. The GFS has been the best performer for the short term
as NAM and RAP were late in picking up the higher rainfall amounts in
the northwest quadrant of the circulation. This area...a deformation
zone of sorts...has seen upwards of 3.5 inches of rain over the last
12 hours or so. The Johnson County Kansas StormWatch observations
show this along with both the legacy and dual pol storm total
precipitation algorithms. The legacy precip algorithm has actually
underestimated by around a half an inch or so even though the Z-R
relationship was changed to tropical yesterday.
As the circulation continues to mainly wobble around Clinton MO we
should see continued rainfall over the above mentioned area...while
the extreme southern zones will have lesser amounts and probably not
much until the low begins to finally move east this afternoon.
Instability remains too weak to support convection so keeping that
out of the forecast for the short term.
The rain should taper off later this afternoon over the western zones
and by evening over the east. Another concern will be fog chances
overnight but thinking that enough stratus will linger such that will
keep fog out for now but day shift should review.
Sunday will see warming temperatures and drying conditions as 850MB
temperatures rebound and moisture from Isaac makes its way into the
Ohio Valley. Expect upper ridging over the area for Labor Day and
Tuesday so we will see continued highs in the 90s.
A front approaches from the north as the upper ridge is
flattened...courtesy of deepening upper trough over south central
Canada. Therefore we will see some chance of thunderstorms return
about mid week and cooler temperatures later in the week.
Adolphson
&&
.AVIATION...
For the 18Z TAFs, last vestiges of post-tropical Isaac lingering
across the Kansas City terminals early this afternoon.
Showers/sprinkles should end at MCI/MKC by 20Z, with associated MVFR
stratus gradually giving way to a broken mid level cloud deck around
11-12Kft. The latter conditions already exist at STJ and will
continue this afternoon. Winds will remain gusty at times from the
NNW (MKC/MCI) to N (STJ) at 15 to 20 knots, subsiding quickly with
sunset.
Skies should firmly clear overnight with winds diminishing to light
and variable. With no significant boundary layer drying expected, am
thinking that fog (potentially dense) is a good bet early Sunday
morning, and have introduced this into the outlook portion of the
TAFs.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
331 PM CDT SAT SEP 1 2012
.DISCUSSION...19Z SURFACE ANALYSIS CENTERS THE REMNANTS OF ISAAC
JUST NORTH OF COLUMBIA MISSOURI. THERE HAS BEEN A BREAK IN THE
SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE MID SOUTH FROM LATE
THIS MORNING THROUGH MID AFTERNOON AS A DRY SLOT /INDICATED BY
WATER VAPOR SATELLITE TRENDS/ HAS BUILT IN TO ARKANSAS AND MUCH OF
THE MID SOUTH. THUNDERSTORMS ARE ONLY BEGINNING TO DEVELOP ONCE
AGAIN UP ACROSS EXTREME NORTHWEST ARKANSAS IN ASSOCIATION WITH AN
APPROACHING SHORTWAVE ASSOCIATED WITH THE REMNANTS OF ISAAC.
TEMPERATURES AS OF 3 PM CDT ARE IN THE MIDDLE 80S TO LOWER 90S
ACROSS THE FORECAST AREA. STRONG TO SEVERE THUNDERSTORM POTENTIAL
TONIGHT AND CONVECTIVE CHANCES INTO NEXT WEEK ARE THE MAIN
FORECAST CHALLENGES FOR THIS AFTERNOON/S FORECAST ISSUANCE.
.SHORT TERM...(TONIGHT THROUGH TUESDAY)...LATEST SHORT TERM
MODELS...ESPECIALLY THE HRRR AND THE 12Z WRF SUGGEST THE
RELATIVELY RAIN FREE CONDITIONS CURRENTLY OCCURRING ACROSS THE MID
SOUTH WILL COME TO AN END THIS EVENING AS ANOTHER SHORTWAVE
ROTATING AROUND THE REMNANTS OF ISAAC MOVES ACROSS THE LOWER
MISSISSIPPI VALLEY TONIGHT. DAYTIME INSTABILITY /SURFACE BASED
CAPE VALUES AVERAGING BETWEEN 2000-3500 J/KG...LI/S BETWEEN -5 TO
-6/ AND STEEP LOW LEVEL LAPSE RATES HAVE RESULTED IN THE
DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS
ARKANSAS...FROM NEAR WALNUT RIDGE BACK THROUGH CENTRAL AND WEST
CENTRAL ARKANSAS. AT THIS TIME BELIEVE THIS ACTIVITY WILL
GRADUALLY INCREASE IN COVERAGE AS IT MOVES ACROSS THE MID SOUTH
TONIGHT...ESPECIALLY ALONG AND NORTH OF I-40. THUS...INCREASED
POPS ACROSS THE ABOVE MENTIONED AREAS. A FEW STRONG TO PERHAPS
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE TONIGHT AS THIS
SHORTWAVE MOVES THROUGH THE MID SOUTH. DAMAGING WINDS WILL BE THE
MAIN THREAT FOR ANY THUNDERSTORM THAT REACHES SEVERE LIMITS. A
TROPICAL AIR MASS COMBINED WITH PRECIPITABLE WATER VALUES ABOVE 2
INCHES SUGGESTS THE POTENTIAL FOR LOCALIZED FLASH FLOODING FROM
HEAVY RAINFALL WITHIN THUNDERSTORMS.
SHORT TERM MODELS INDICATE THE REMNANTS OF ISAAC WILL GRADUALLY
MOVE EAST SOUTHEAST TO THE OHIO AND TENNESSEE VALLEYS FOR SUNDAY
THROUGH TUESDAY. AS A RESULT...A CONTINUED CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL PERSIST BUT GRADUALLY DECREASE THROUGH THE
REMAINDER OF THE PERIOD. A STRONG THUNDERSTORM OR TWO CONTAINING
HEAVY RAINFALL AND GUSTY WINDS WILL ALSO BE POSSIBLE ON SUNDAY
AFTERNOON.
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)...12Z GFS/ECMWF LONG
RANGE MODELS INDICATE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
PERSIST ACROSS THE AREA THROUGHOUT THE PERIOD AS ANOTHER COLD
FRONT DROPS INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY NIGHT AND
THEN STALLS OUT ACROSS THE AREA INTO NEXT WEEKEND. KEPT
PRECIPITATION CHANCES ON THE LOW END FOR THE TIME BEING AS THERE
ARE SOME TIMING/COVERAGE DIFFERENCES BETWEEN THE LONG TERM MODEL
SOLUTIONS.
CJC
&&
.AVIATION...
18Z TAFS
STARTING TO SEE ANOTHER ROUND OF SHOWERS/STORMS BEGIN TO DEVELOP
ACROSS THE MIDSOUTH AS TEMPERATURES CLIMB INTO THE UPPER 80S.
SHOWERS WILL BE HIT AND MISS THROUGH MOST OF THE AFTERNOON...MUCH
LIKE YESTERDAY. AROUND 00-04Z A BAND OF POSSIBLY STRONGER SHOWERS
AND THUNDERSTORMS IS EXPECTED TO DEVELOP NEAR JBR TO LITTLE ROCK
AND MOVE TO THE EAST. TRIED TO TIME THIS UN-DEVELOPED LINE BY
ADDING VCTS TO JBR...THEN MEM AND MKL. HOWEVER TIMING OF THIS
FEATURE WILL BECOME MUCH MORE CERTAIN AFTER...OR EVEN IF IT
DEVELOPS. WILL AMEND WHEN THERE IS SOMETHING MORE CONCRETE TO
TRACK. STRONG WIND AND BRIEF IFR VISIBILITY DUE TO HEAVY RAIN CAN
BE EXPECTED. OTHERWISE...EXPECT PRECIPITATION INTENSITY AND
COVERAGE TO DIMINISH BY 06Z...WITH MVFR TO IFR LOW CLOUDS DURING
TH EARLY MORNING HOURS.
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 76 93 76 94 / 60 40 40 20
MKL 75 89 72 89 / 70 60 50 30
JBR 75 90 72 93 / 70 50 30 20
TUP 74 90 73 92 / 40 40 50 30
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$