Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/29/13
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
205 PM MST TUE AUG 27 2013
&&
.SYNOPSIS...
THUNDERSTORMS CHANCES WILL BE REDUCING BY SOMEWHAT DRIER AIR WORKING
ITS WAY IN FROM THE EAST THROUGH THE DAY ON WEDNESDAY...WITH JUST
ISOLATED STORMS FORECAST OVER THE LOWER DESERTS OF SOUTH CENTRAL
ARIZONA. AN INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED
BEGINNING WEDNESDAY EVENING...WITH EVEN A BIGGER INCREASE ON
THURSDAY AND FRIDAY AS A WEATHER DISTURBANCE APPROACHES FROM THE
SOUTH. NEAR NORMAL TEMPERATURES ON WEDNESDAY ARE EXPECTED TO FALL TO
BELOW NORMAL VALUES ON THURSDAY AND FRIDAY.
&&
.DISCUSSION...
LATEST VISUAL SATELLITE AND RADAR IMAGERY IS NOW SHOWING ISOLATED
SHOWERS AND THUNDERSTORMS DEVELOPING OVER SOUTHEAST...AND THE HIGHER
ELEVATIONS OF SOUTH-CENTRAL AND NORTHERN ARIZONA. HOWEVER...LATEST
IR IMAGERY CONTINUES TO SHOW DRIER AIR CONTINUING TO TRY TO PITCH
OFF/MIX OUT THE PLUME OF DEEP TROPICAL MOISTURE THAT IS STILL
STRETCHED FROM NORTH TO SOUTH OVER CENTRAL ARIZONA. ALSO...SURFACE
OBS ARE SHOWING SOMEWHAT DRIER AIR IS MOVING INTO SOUTHEAST AND
EAST-CENTRAL ARIZONA...WITH THE DEWPOINT AT TUCSON NOW DOWN TO 52F
FROM THE MID TO UPPER 60S EARLY THIS MORNING. LATEST HRRR MODEL RUN
CONTINUES TO DISSIPATE VIRTUALLY ANY CONVECTIVE ACTIVITY THAT TRIES
TO FORM BEFORE IT CAN MAKE ITS WAY INTO SOUTH-CENTRAL ARIZONA.
THUS...EVEN THOUGH THERE IS CERTAINLY STILL A CHANCE FOR AN ISOLATED
THUNDERSTORM ANYWHERE IN OUR CWA THIS AFTERNOON OR
EVENING...CURRENTLY BELIEVE THAT ANY ACTIVITY THAT DOES DEVELOP WILL
NOT LAST LONG...AND WE WILL CERTAINLY NOT SEE ANYTHING CLOSE TO THE
AMOUNT OF ACTIVITY THAT WE SAW LAST NIGHT
AFTER WHAT WILL BE LIKELY A QUIET MORNING TOMORROW...AN UPRAMPING IN
MONSOON ACTIVITY CONTINUES TO BE IN THE CARDS STARTING TOMORROW
EVENING...AND ESPECIALLY ON THURSDAY AND FRIDAY. LATEST MODEL OUTPUT
CONTINUES TO BRING ANOTHER PLUME OF TROPICAL MOISTURE NORTHWARD INTO
THE REGION AS A STRONG EASTERLY WAVE...THAT IS LIKELY THE REMAINS OF
TROPICAL STORM FERNAND...MOVES NORTHWESTWARD JUST OFF THE WEST COAST
OF MEXICO...EVENTUALLY ENDING OFF THE COAST OF SOUTHERN CA BY EARLY
SATURDAY. THE BIGGEST DIFFERENCES BETWEEN THE MODELS IS THE TIMING
OF THE ARRIVAL OF THE DEEP MOISTURE...WITH THE NAM BEGINNING TO MOVE
IT INTO SOUTHERN ARIZONA BY LATE WEDNESDAY NIGHT...AND THE GFS AND
ECMWF NOT MOVING IT IN UNTIL THURSDAY MORNING. THERE ARE ALSO
DIFFERENCES IN THE AMOUNT OF MOISTURE THAT IS IMPORTED INTO THE
REGION...WITH THE GFS AND NAM PUSHING PWAT VALUES INTO THE 2.00-2.40
INCH RANGE...AND THE ECMWF ONLY PUSHING VALUES INTO THE 1.75-2.00
RANGE. EITHER WAY...IT LOOKS LIKE THAT ANOTHER ROUND OF WIDESPREAD
WETTING RAINS IS LIKELY OVER THE REGION...WITH THE MOISTURE-RICH
ENVIRONMENT LIKELY LEADING TO LOCALLY HEAVY DOWNPOURS AND POSSIBLE
LOCAL FLOODING ISSUES. TEMPERATURES ON THURSDAY AND FRIDAY QUITE
LIKELY WILL BE KEPT IN THE 90S ACROSS THE LOWER DESERTS BY ALL THE
CLOUDS AND RAIN THAT IS EXPECTED OVER THE REGION...WITH PERHAPS SOME
ISOLATED AREAS NOT GETTING OUT OF THE 80S ON AT LEAST ONE OF THE
DAYS.
FORECAST UNCERTAINTY CONTINUES TO BE AN ISSUE OVER THE WEEKEND...AS
ECMWF FORECASTS BEGINNING TO SCOUR OUT SOME MOISTURE WHILE
RETROGRADING RIDGING AND SUBSIDENCE INTO THE REGION...WHILE GFS
FORECASTS MAINTAIN WEAK PERTURBATIONS AND FAVORABLE MOIST VERTICAL
MOTION PROFILES. EITHER SCENARIO APPEARS EQUALLY LIKELY AT THIS
TIME...AND COULD NOT JUSTIFY ADVERTISING A FORECAST TERRIBLY FAR
ABOVE CLIMATOLOGY GIVEN THE OVERALL UNCERTAINTY AND LOWER FORECAST
CONFIDENCE.
&&
.AVIATION...
ALTHOUGH THE ATMOSPHERE OVER THE SOUTHCENTRAL DESERTS WAS WORKED
OVER FAIRLY HEAVILY LAST NIGHT...WITH WIDESPREAD THUNDERSTORM RAINS
COOLING THE BOUNDARY LAYER...MESOANALYSIS GRAPHICS SHOW HIGH CAPE
VALUES DEVELOPING FROM WESTERN MARICOPA COUNTY SOUTH AND EAST INTO
PIMA COUNTY. SUFFICIENT SUNSHINE OVER SERN AZ HAS ALLOWED CONVECTION
TO BEGIN DEVELOPING AGAIN AND STEERING FLOW IS AGAIN FROM THE
SOUTHEAST.
CENTRAL DESERT TAFS DO NOT REFLECT A THUNDERSTORM THREAT AT THIS
TIME...HOWEVER POTENTIAL IS GROWING THAT ISOLATED STORMS MAY DEVELOP
AND MOVE INTO THE AIRFIELDS LATER THIS AFTERNOON...PROBABLY AFTER 4
PM...AND BRING GUSTY WINDS AND HEAVY RAIN ONCE AGAIN. USUALLY IT IS
VERY HARD TO GET TWO CONSECUTIVE ACTIVE WEATHER DAYS IN THE SAME
AREA BUT WE ARE STILL QUITE MOIST AND INSTABILITY IS GROWING. WE
WILL CONTINUE TO MONITOR THE GROWING THREAT...AND WILL UPDATE THE
TAFS TO INCLUDE VCTS OR TEMPO TSRA SHOULD THE CHANCE FOR STORMS
CONTINUE TO INCREASE.
THERE WILL BE INCREASING CHANCES FOR AFTN/EVE THUNDERSTORMS IN THE
CENTRAL DESERTS TOMORROW...AND THEN INTO THE DAY ON THURSDAY AS
TROPICAL MOISTURE FROM FERNAND MOVES INTO THE AREA.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
FEW TO SCATTERED MID AND HIGH LEVEL CLOUDS ARE EXPECTED THROUGH THE
TAF PERIOD WITH WINDS LESS THAN 10 KNOTS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
TROPICAL MOISTURE FROM FORMER TROPICAL STORM FERNAND WILL SWEEP INTO
THE REGION FROM THE SOUTHEAST ON FRIDAY...LEADING TO A GOOD CHANCE
OF SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN. MOISTURE WILL
LINGER THROUGH THE WEEKEND...LEADING TO AN ELEVATED THREAT OF
THUNDERSTORMS...AND THEN THIN SOMEWHAT EARLY NEXT WEEK AS NORMAL
MONSOONAL CONDITIONS WILL PREVAIL. MINIMUM RELATIVE HUMIDITIES WILL
BE VERY HIGH THROUGH THE WEEKEND...MOSTLY GREATER THAN 30 PERCENT
OVER THE DESERTS...AND THEN WILL FALL INTO THE 20S BY MONDAY.
TEMPERATURES WILL REMAIN BELOW SEASONAL NORMALS THROUGH THE FIVE DAY
PERIOD. WINDS WILL BE GENERALLY ON THE LIGHT SIDE EACH DAY FOLLOWING
NORMAL DIURNAL TENDENCIES WITH TYPICAL AFTERNOON GUSTINESS...
ESPECIALLY OVER FAVORED HIGHER TERRAIN LOCATIONS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...PERCHA/MO
AVIATION....CB
FIRE WEATHER...CB
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
1205 PM MST TUE AUG 27 2013
.UPDATE...UPDATED AVIATION DISCUSSION.
&&
.SYNOPSIS...
OVERALL PRECIPITATION CHANCES WILL DECREASE SLIGHTLY TODAY AND
WEDNESDAY AS DRIER AIR ATTEMPTS TO SETTLE OVER THE REGION FROM THE
EAST....HOWEVER RESIDUAL MOISTURE WILL STILL SUPPORT A FEW STORMS.
A LARGER DISTURBANCE WILL MOVE INTO THE REGION AND REESTABLISH MORE
EXTENSIVE THUNDERSTORM ACTIVITY THURSDAY AND FRIDAY. WITH THE
EXCEPTION OF SOME WARMING TO NEAR AVERAGE LEVELS THE NEXT COUPLE
DAYS...TEMPERATURES WILL GENERALLY REMAIN BELOW THE SEASONAL NORMAL.
&&
.DISCUSSION...
A MUCH QUIETER MORNING ACROSS OUR CWA WHEN COMPARED TO ALL OF
YESTERDAY/S ACTIVITY OVER SOUTH-CENTRAL ARIZONA. THE DISTURBANCE
THAT TRIGGERED THE STORMS YESTERDAY EVENING HAS NOW MOVING RAPIDLY
NORTHWARD INTO UTAH...WITH JUST SOME LEFT-OVER SHOWERS AND A FEW TS
BEING DETECTED ON RADAR OVER THE WESTERN 1/2 OF THE FLAGSTAFF CWA.
BASED ON CURRENT OBSERVATIONS AND RADAR TRENDS...HAVE REDUCED POPS
TO JUST SLIGHT CHANCE ONES OVER LA PAZ AND EXTREME NORTHWEST
MARICOPA COUNTIES FOR THE REMAINDER OF THE MORNING AND EARLY
AFTERNOON HOURS.
GIVEN THE LAST FEW RUNS OF THE HIGH-RES HRRR MODEL...WHICH DID VERY
WELL FORECASTING YESTERDAY/S CONVECTIVE ACTIVITY...AND NOW IS
FORECASTING VERY LITTLE...OR NO CONVECTIVE DEVELOPMENT FOR TODAY AND
TONIGHT...THERE IS NOW EVEN GREATER CONFIDENCE THAT THIS
AFTERNOON/EVENING SHOULD BE A PRETTY QUIET ONE. THUS...HAVE LEFT THE
SHORT-TERM GRIDS FOR THE AFTERNOON/EVENING ALONE...WHICH ARE
FORECASTING JUST A SLIGHT CHANCE FOR STORMS OVER MOST AREAS OF OUR
CWA.
&&
.PREVIOUS DISCUSSION...
EARLY THIS MORNING...AN EASTERLY WAVE WAS PROPAGATING NORTH INTO
SWRN NEW MEXICO WITH THE RIGHT REAR JET DIVERGENCE FIELD LIFTING
INTO NRN ARIZONA. THE PLUME OF DEEP TROPICAL MOISTURE OVER CNTRL/WRN
ARIZONA WAS BECOMING PINCHED BY ADVECTION OF DRIER MID LEVEL AIR
FROM BOTH THE EAST AND WEST PER WV IMAGERY. THIS SCENARIO WAS
ALREADY BEING SEEN IN 00Z/03Z REGIONAL SOUNDING DATA WITH MIXING
RATIOS IN THE H7-H8 LAYER FALLING BELOW 10 G/KG. DESPITE THIS...THE
COMBINATION OF SFC HEATING...MOISTURE ALOFT...AND FAVORABLE ASCENT
SUPPORTED THUNDERSTORM FORMATION ALONG OUTFLOWS AT LOWER ELEVATIONS
THROUGH THE EVENING HOURS.
OPERATIONAL AND HI RES MODELS ONCE AGAIN INDICATE LESSER ACTIVITY
THIS AFTERNOON AND EVENING IN THE WAKE OF THE WAVE PASSAGE AND
GENERAL DRYING TREND THROUGH THE ATMOSPHERIC COLUMN. OF COURSE...THE
SAME 00Z MODELS YESTERDAY FAILED TO CAPTURE THE EXTENT OF ACTIVITY
LAST EVENING...AND IT WASNT UNTIL 12Z INITIALIZATIONS THAT A
SOMEWHAT BETTER OUTCOME WAS ADVERTISED. WITH RESIDUAL MOISTURE LEFT
IN BOTH THE LOWER BOUNDARY LAYER AND MID LEVELS...STILL CANNOT
DISCOUNT ANY PULSING STORM ACTIVITY TODAY...THOUGH MORE ORGANIZED OR
PERSISTENT ACTIVITY SHOULD BE LACKING. OTHERWISE...TEMPERATURES
SHOULD REBOUND TO NEAR AVERAGE LEVELS THIS AFTERNOON...WITH THE
FORECAST TAILORED TOWARDS RAW MODEL CONSENSUS.
OVERALL MOISTURE PROFILES WILL ONLY CHANGE SLIGHTLY WEDNESDAY...WITH
SFC-H7 MIXING RATIOS IN THAT MARGINALLY SUPPORTIVE 10-12 G/KG RANGE.
HOWEVER...BETTER DYNAMICAL ASCENT ON THE LEADING EDGE OF AN EASTERLY
WAVE AND A CORRESPONDING RENEWED PUSH OF DEEPER MOISTURE WILL BEGIN
TO ENTER SERN ARIZONA...HELPING ORGANIZE MORE ROBUST THUNDERSTORM
DEVELOPMENT. BIGGEST QUESTION REMAINS WHETHER THE ATMOSPHERE AT
LOWER ELEVATIONS OF CNTRL ARIZONA WILL ALLOW FOR MORE THAN DECAYING
OUTFLOWS. KEPT RELATIVELY MODEST POPS AWAITING THE MAIN BRUNT OF THE
WAVE AND MOISTURE FLUX BEYOND WEDNESDAY EVENING.
OPERATIONAL MODELS CONTINUE TO SUGGEST A VERY WELL DEFINED
EASTERLY WAVE...PRONOUNCED UPPER DIFLUENCE...AND THICK TROPICAL
MOISTURE PROGRESSING INTO THE FORECAST AREA THURSDAY AND FRIDAY.
PARTIALLY THE REMNANT CIRCULATION OF OLD ATLANTIC TROPICAL CYCLONE
FERNAND COMBINED WITH A SOUTHEAST PACIFIC MOISTURE
TAP...PRECIPITATION MAY COME IN WAVES WITH AN INITIAL BAND OF
ELEVATED LIFT PRECEDING THE WAVE...THEN DIURNAL CONVECTIVELY
GENERATED STORMS. TIMING AND LOCATION UNCERTAINTIES STILL PRECLUDE A
MUCH STRONGER POP MENTION FOR ANY SPECIFIC TIME FRAME...HOWEVER
MODEL SOUNDING FORECASTS OF PROLONGED PERIODS OF PWATS GREATER THAN
2.0 INCHES AND BOUNDARY LAYER MIXING RATIOS AOA 15 G/KG SUGGEST SOME
AMOUNT OF PRECIPITATION WILL BE INEVITABLE SOMETIME DURING THE
THURSDAY/FRIDAY TIME FRAME ACROSS MUCH OF THE CWA.
FORECAST UNCERTAINTY BEGINS TO GROW OVER THE WEEKEND...AS ECMWF
FORECASTS BEGIN TO SCOUR OUT SOME MOISTURE WHILE RETROGRADING
RIDGING AND SUBSIDENCE INTO THE REGION...WHILE GFS FORECASTS
MAINTAIN WEAK PERTURBATIONS AND FAVORABLE MOIST VERTICAL MOTION
PROFILES. EITHER SCENARIO APPEARS EQUALLY LIKELY AT THIS TIME...AND
COULD NOT JUSTIFY ADVERTISING A FORECAST TERRIBLY FAR FROM
CLIMATOLOGY GIVEN THE OVERALL UNCERTAINTY AND LOWER FORECAST
CONFIDENCE.
&&
.AVIATION...
ALTHOUGH THE ATMOSPHERE OVER THE SOUTHCENTRAL DESERTS WAS WORKED
OVER FAIRLY HEAVILY LAST NIGHT...WITH WIDESPREAD THUNDERSTORM RAINS
COOLING THE BOUNDARY LAYER...MESOANALYSIS GRAPHICS SHOW HIGH CAPE
VALUES DEVELOPING FROM WESTERN MARICOPA COUNTY SOUTH AND EAST INTO
PIMA COUNTY. SUFFICIENT SUNSHINE OVER SERN AZ HAS ALLOWED CONVECTION
TO BEGIN DEVELOPING AGAIN AND STEERING FLOW IS AGAIN FROM THE
SOUTHEAST.
CENTRAL DESERT TAFS DO NOT REFLECT A THUNDERSTORM THREAT AT THIS
TIME...HOWEVER POTENTIAL IS GROWING THAT ISOLATED STORMS MAY DEVELOP
AND MOVE INTO THE AIRFIELDS LATER THIS AFTERNOON...PROBABLY AFTER 4
PM...AND BRING GUSTY WINDS AND HEAVY RAIN ONCE AGAIN. USUALLY IT IS
VERY HARD TO GET TWO CONSECUTIVE ACTIVE WEATHER DAYS IN THE SAME
AREA BUT WE ARE STILL QUITE MOIST AND INSTABILITY IS GROWING. WE
WILL CONTINUE TO MONITOR THE GROWING THREAT...AND WILL UPDATE THE
TAFS TO INCLUDE VCTS OR TEMPO TSRA SHOULD THE CHANCE FOR STORMS
CONTINUE TO INCREASE.
THERE WILL BE INCREASING CHANCES FOR AFTN/EVE THUNDERSTORMS IN THE
CENTRAL DESERTS TOMORROW...AND THEN INTO THE DAY ON THURSDAY AS
TROPICAL MOISTURE FROM FERNAND MOVES INTO THE AREA.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
FEW TO SCATTERED MID AND HIGH LEVEL CLOUDS ARE EXPECTED THROUGH THE
TAF PERIOD WITH WINDS LESS THAN 10 KNOTS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
ANOTHER ACTIVE MONSOON PERIOD IS EXPECTED FROM THURSDAY ONWARD INTO
THE WEEKEND AS DEEP SOUTHERLY FLOW IMPORTS COPIOUS MOISTURE INTO THE
REGION...WITH EMBEDDED WEATHER DISTURBANCES HELPING TO ENHANCE
CONVECTIVE ACTIVITY...WITH A GOOD CHANCE OF WIDESPREAD WETTING RAINS
ACROSS THE ENTIRE DESERT SOUTHWEST. MINIMUM HUMIDITY VALUES ARE
EXPECTED TO ONLY FALL INTO THE 30 TO 40 PERCENT RANGE ACROSS THE
LOWER DESERTS...AND INTO THE 40 TO 55 PERCENT RANGE ACROSS THE
HIGHER ELEVATIONS EACH DAY...WITH EXCELLENT OVERNIGHT RECOVERIES.
THUNDERSTORM ACTIVITY WILL DECREASE SOMEWHAT ON MONDAY AS STRONG
RIDGING BEGINS TO BUILD IN FROM THE EAST. WINDS ARE EXPECTED TO
REMAIN ON THE LIGHT SIDE THROUGH THE PERIOD...EXCEPT NEAR
THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...PERCHA/MO
AVIATION....CB
FIRE WEATHER...PERCHA
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
850 AM MST TUE AUG 27 2013
&&
.SYNOPSIS...
OVERALL PRECIPITATION CHANCES WILL DECREASE SLIGHTLY TODAY AND
WEDNESDAY AS DRIER AIR ATTEMPTS TO SETTLE OVER THE REGION FROM THE
EAST....HOWEVER RESIDUAL MOISTURE WILL STILL SUPPORT A FEW STORMS.
A LARGER DISTURBANCE WILL MOVE INTO THE REGION AND REESTABLISH MORE
EXTENSIVE THUNDERSTORM ACTIVITY THURSDAY AND FRIDAY. WITH THE
EXCEPTION OF SOME WARMING TO NEAR AVERAGE LEVELS THE NEXT COUPLE
DAYS...TEMPERATURES WILL GENERALLY REMAIN BELOW THE SEASONAL NORMAL.
&&
.DISCUSSION...
A MUCH QUIETER MORNING ACROSS OUR CWA WHEN COMPARED TO ALL OF
YESTERDAY/S ACTIVITY OVER SOUTH-CENTRAL ARIZONA. THE DISTURBANCE
THAT TRIGGERED THE STORMS YESTERDAY EVENING HAS NOW MOVING RAPIDLY
NORTHWARD INTO UTAH...WITH JUST SOME LEFT-OVER SHOWERS AND A FEW TS
BEING DETECTED ON RADAR OVER THE WESTERN 1/2 OF THE FLAGSTAFF CWA.
BASED ON CURRENT OBSERVATIONS AND RADAR TRENDS...HAVE REDUCED POPS
TO JUST SLIGHT CHANCE ONES OVER LA PAZ AND EXTREME NORTHWEST
MARICOPA COUNTIES FOR THE REMAINDER OF THE MORNING AND EARLY
AFTERNOON HOURS.
GIVEN THE LAST FEW RUNS OF THE HIGH-RES HRRR MODEL...WHICH DID VERY
WELL FORECASTING YESTERDAY/S CONVECTIVE ACTIVITY...AND NOW IS
FORECASTING VERY LITTLE...OR NO CONVECTIVE DEVELOPMENT FOR TODAY AND
TONIGHT...THERE IS NOW EVEN GREATER CONFIDENCE THAT THIS
AFTERNOON/EVENING SHOULD BE A PRETTY QUIET ONE. THUS...HAVE LEFT THE
SHORT-TERM GRIDS FOR THE AFTERNOON/EVENING ALONE...WHICH ARE
FORECASTING JUST A SLIGHT CHANCE FOR STORMS OVER MOST AREAS OF OUR
CWA.
&&
.PREVIOUS DISCUSSION...
EARLY THIS MORNING...AN EASTERLY WAVE WAS PROPAGATING NORTH INTO
SWRN NEW MEXICO WITH THE RIGHT REAR JET DIVERGENCE FIELD LIFTING
INTO NRN ARIZONA. THE PLUME OF DEEP TROPICAL MOISTURE OVER CNTRL/WRN
ARIZONA WAS BECOMING PINCHED BY ADVECTION OF DRIER MID LEVEL AIR
FROM BOTH THE EAST AND WEST PER WV IMAGERY. THIS SCENARIO WAS
ALREADY BEING SEEN IN 00Z/03Z REGIONAL SOUNDING DATA WITH MIXING
RATIOS IN THE H7-H8 LAYER FALLING BELOW 10 G/KG. DESPITE THIS...THE
COMBINATION OF SFC HEATING...MOISTURE ALOFT...AND FAVORABLE ASCENT
SUPPORTED THUNDERSTORM FORMATION ALONG OUTFLOWS AT LOWER ELEVATIONS
THROUGH THE EVENING HOURS.
OPERATIONAL AND HI RES MODELS ONCE AGAIN INDICATE LESSER ACTIVITY
THIS AFTERNOON AND EVENING IN THE WAKE OF THE WAVE PASSAGE AND
GENERAL DRYING TREND THROUGH THE ATMOSPHERIC COLUMN. OF COURSE...THE
SAME 00Z MODELS YESTERDAY FAILED TO CAPTURE THE EXTENT OF ACTIVITY
LAST EVENING...AND IT WASNT UNTIL 12Z INITIALIZATIONS THAT A
SOMEWHAT BETTER OUTCOME WAS ADVERTISED. WITH RESIDUAL MOISTURE LEFT
IN BOTH THE LOWER BOUNDARY LAYER AND MID LEVELS...STILL CANNOT
DISCOUNT ANY PULSING STORM ACTIVITY TODAY...THOUGH MORE ORGANIZED OR
PERSISTENT ACTIVITY SHOULD BE LACKING. OTHERWISE...TEMPERATURES
SHOULD REBOUND TO NEAR AVERAGE LEVELS THIS AFTERNOON...WITH THE
FORECAST TAILORED TOWARDS RAW MODEL CONSENSUS.
OVERALL MOISTURE PROFILES WILL ONLY CHANGE SLIGHTLY WEDNESDAY...WITH
SFC-H7 MIXING RATIOS IN THAT MARGINALLY SUPPORTIVE 10-12 G/KG RANGE.
HOWEVER...BETTER DYNAMICAL ASCENT ON THE LEADING EDGE OF AN EASTERLY
WAVE AND A CORRESPONDING RENEWED PUSH OF DEEPER MOISTURE WILL BEGIN
TO ENTER SERN ARIZONA...HELPING ORGANIZE MORE ROBUST THUNDERSTORM
DEVELOPMENT. BIGGEST QUESTION REMAINS WHETHER THE ATMOSPHERE AT
LOWER ELEVATIONS OF CNTRL ARIZONA WILL ALLOW FOR MORE THAN DECAYING
OUTFLOWS. KEPT RELATIVELY MODEST POPS AWAITING THE MAIN BRUNT OF THE
WAVE AND MOISTURE FLUX BEYOND WEDNESDAY EVENING.
OPERATIONAL MODELS CONTINUE TO SUGGEST A VERY WELL DEFINED
EASTERLY WAVE...PRONOUNCED UPPER DIFLUENCE...AND THICK TROPICAL
MOISTURE PROGRESSING INTO THE FORECAST AREA THURSDAY AND FRIDAY.
PARTIALLY THE REMNANT CIRCULATION OF OLD ATLANTIC TROPICAL CYCLONE
FERNAND COMBINED WITH A SOUTHEAST PACIFIC MOISTURE
TAP...PRECIPITATION MAY COME IN WAVES WITH AN INITIAL BAND OF
ELEVATED LIFT PRECEDING THE WAVE...THEN DIURNAL CONVECTIVELY
GENERATED STORMS. TIMING AND LOCATION UNCERTAINTIES STILL PRECLUDE A
MUCH STRONGER POP MENTION FOR ANY SPECIFIC TIME FRAME...HOWEVER
MODEL SOUNDING FORECASTS OF PROLONGED PERIODS OF PWATS GREATER THAN
2.0 INCHES AND BOUNDARY LAYER MIXING RATIOS AOA 15 G/KG SUGGEST SOME
AMOUNT OF PRECIPITATION WILL BE INEVITABLE SOMETIME DURING THE
THURSDAY/FRIDAY TIME FRAME ACROSS MUCH OF THE CWA.
FORECAST UNCERTAINTY BEGINS TO GROW OVER THE WEEKEND...AS ECMWF
FORECASTS BEGIN TO SCOUR OUT SOME MOISTURE WHILE RETROGRADING
RIDGING AND SUBSIDENCE INTO THE REGION...WHILE GFS FORECASTS
MAINTAIN WEAK PERTURBATIONS AND FAVORABLE MOIST VERTICAL MOTION
PROFILES. EITHER SCENARIO APPEARS EQUALLY LIKELY AT THIS TIME...AND
COULD NOT JUSTIFY ADVERTISING A FORECAST TERRIBLY FAR FROM
CLIMATOLOGY GIVEN THE OVERALL UNCERTAINTY AND LOWER FORECAST
CONFIDENCE.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
BROKEN MID AND HIGH CLOUDS WILL GRADUALLY THIN AND BECOME MORE
SCATTERED THROUGHOUT THE MORNING HOURS. WINDS ARE EXPECTED TO
INCREASE OUT OF THE SOUTHEAST BY MID TO LATE MORNING AND BECOME
GUSTY AT TIMES BEFORE DIMINISHING LATE THIS AFTERNOON. THERE WILL
STILL BE A POSSIBILITY OF ISOLATED SHOWERS AND THUNDERSTORMS LATE
THIS AFTERNOON AND EVENING...BUT DEFINITELY LESSER CHANCES THAN
YESTERDAY.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
FEW TO SCATTERED MID AND HIGH LEVEL CLOUDS ARE EXPECTED THROUGH THE
TAF PERIOD WITH WINDS LESS THAN 10 KNOTS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
ANOTHER ACTIVE MONSOON PERIOD IS EXPECTED FROM THURSDAY ONWARD INTO
THE WEEKEND AS DEEP SOUTHERLY FLOW IMPORTS COPIOUS MOISTURE INTO THE
REGION...WITH EMBEDDED WEATHER DISTURBANCES HELPING TO ENHANCE
CONVECTIVE ACTIVITY...WITH A GOOD CHANCE OF WIDESPREAD WETTING RAINS
ACROSS THE ENTIRE DESERT SOUTHWEST. MINIMUM HUMIDITY VALUES ARE
EXPECTED TO ONLY FALL INTO THE 30 TO 40 PERCENT RANGE ACROSS THE
LOWER DESERTS...AND INTO THE 40 TO 55 PERCENT RANGE ACROSS THE
HIGHER ELEVATIONS EACH DAY...WITH EXCELLENT OVERNIGHT RECOVERIES.
THUNDERSTORM ACTIVITY WILL DECREASE SOMEWHAT ON MONDAY AS STRONG
RIDGING BEGINS TO BUILD IN FROM THE EAST. WINDS ARE EXPECTED TO
REMAIN ON THE LIGHT SIDE THROUGH THE PERIOD...EXCEPT NEAR
THUNDERSTORMS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...PERCHA/MO
AVIATION....KUHLMAN
FIRE WEATHER...PERCHA
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
912 AM MDT TUE AUG 27 2013
.UPDATE...FORECAST LOOKS ON TRACK WITH SOMEWHAT LOWER
PRECIPITABLE WATER BUT HIGHER CAPES OFF 500-1000 J/KG. THE 12Z
DENVER SOUNDING DOES SHOW A RATHER STRONG SUBSIDENCE INVERSION
NEAR 520 MB...BUT WITH SUFFICIENT HEATING AND LOW LEVEL MOISTURE
WE SHOULD BE ABLE TO POP THROUGH THE CAP. HIGHEST COVERAGE OF
STORMS WILL UNDOUBTEDLY BEING ALONG THE FRONT RANGE
MOUNTAINS/FOOTHILLS... WITH CHANCES DECREASING RATHER QUICKLY TO
THE EAST. BEST CHANCE OF ANY STORMS MOVING OFF THE FOOTHILLS WOULD
BE FROM THE WESTERN SUBURBS OF DENVER TOWARD FORT COLLINS AND
NORTHERN WELD COUNTY GIVEN STRONGER SUBSIDENCE INVERSION TOWARD
THE SOUTHEAST. LATEST RAP AND HRRR RUNS ALSO SUPPORT THIS.
&&
.AVIATION...CURRENT FORECAST LOOKS GOOD. MOST THUNDERSTORMS WILL
REMAIN CONFINED TO LOCATIONS IN/NEAR THE FOOTHILLS WITH NORTHWEST
APPROACH GATE HAVING THUNDERSTORMS 18Z-03Z...AND SCATTERED STORMS
AT SOUTHWEST APPROACH GATE. AT THE AIRPORTS...KBJC WOULD SEE A
LITTLE BETTER CHANCE OF -TSRA AND GUSTY OUTFLOW WINDS TO AROUND
30-35 KTS...WHILE LOWER CHANCE FARTHER AWAY FROM THE FOOTHILLS AT
KDEN AND KAPA.
&&
.HYDROLOGY...LOCALLY HEAVY RAIN STILL POSSIBLE FROM STRONGER
STORMS THIS AFTERNOON AND EVENING DUE TO A LITTLE HIGHER CAPE.
STRONGEST STORMS WOULD BE CAPABLE OF PRODUCING 0.50 TO 1.0 INCH
IN 20-30 MINUTES...AND THUS SOME MINOR FLOODING THREAT IN
FOOTHILL BURN SCARS.
&&
.PREV DISCUSSION... /ISSUED 328 AM MDT TUE AUG 27 2013/
SHORT TERM...ANOTHER REPEAT OF THE PAST FEW DAYS IS EXPECTED AS
AN UPPER LEVEL HIGH CONTINUES TO RESIDE OVER THE MIDDLE OF THE
COUNTRY. AIRMASS DRIES A LITTLE WITH PRECIPITABLE WATER VALUES
TOPPING OUT AROUND AN INCH. INSTABILITY WILL INCREASE TO WITH
VALUES UP TO 1000 J/KG OVER THE HIGHER TERRAIN AND FRONT RANGE.
EVEN THOUGH THE AIRMASS DRIES A LITTLE...STORMS MAY BE ABLE TO
PRODUCE MORE HEAVY AND PERHAPS SMALL HAIL BECAUSE OF THE BETTER
INSTABILITY LEADING TO STRONGER UPDRAFTS.
SCATTERED STORMS WILL DEVELOP OVER THE HIGHER TERRAIN ONCE AGAIN
THIS AFTERNOON. SCATTERED TO ISOLATED STORMS ARE EXPECTED ALONG THE
FRONT RANGE LATE THIS AFTERNOON AND EARLY EVENING. WARM AIR ALOFT
WILL CAP CONVECTION OVER THE EASTERN PLAINS AGAIN.
DRIER MOVING INTO THE AREA WILL LEAD TO MOSTLY CLEAR SKIES AFTER
MIDNIGHT. LOWS WILL REMAIN ABOVE NORMAL DUE TO THE WARM AIRMASS WITH
LOWS IN THE UPPER 50S TO MID 60S.
LONG TERM...AT 12Z WEDNESDAY...MODELS SHOW THE CENTER OF AN UPPER
RIDGE OVER WEST CENTRAL MISSOURI. IT MOVES LITTLE THROUGH
THURSDAY...THEN THE CENTER REDEVELOPS OVER COLORADO THURSDAY
NIGHT. THE MODELS CONTINUE TO SHOW A WEAK UPPER LOW CIRCULATION
WITHIN THE RIDGE...WEDNESDAY THROUGH THURSDAY. IT IS MAINLY
LOCATED OVER WESTERN KANSAS. THE FLOW ALOFT FOR THE CWA IS WEAK
AND NORTH OR NORTHEASTERLY MUCH OF THE FOUR PERIODS DUE THE WEAK
UPPER LOW. THERE IS NO SYNOPTIC SCALE ENERGY TO SPEAK OF ALL FOUR
PERIODS. FOR MOISTURE...IT DEFINITELY DRIES OUT SOMEWHAT WEDNESDAY
AND THURSDAY. PRECIPITABLE WATER VALUES ARE IN THE 0.60 TO 0.80
INCH RANGE OVER THE PLAINS WEDNESDAY THROUGH THURSDAY NIGHT. THE
BOUNDARY LAYER DEW POINTS ARE PROGGED TO STAY IN THE 40S F OVER
MUCH OF THE CWA ALL FOUR PERIODS. THERE IS SOME CAPE AROUND LATE
DAY WEDNESDAY...MOSTLY IN THE MOUNTAINS AND FOOTHILLS...WITH
NEARLY NONE OVER THE PLAINS. THURSDAY IS SIMILAR. THE LAPSE RATE
FIELDS SHOW A FAIRLY DECENT MID LEVEL CAP IN PLACE OVER THE PLAINS
FOR SURE LATE DAY WEDNESDAY AND LATE DAY THURSDAY. IT IS MORE
PRONOUNCED ON THE GFS. THE QPF FIELDS HAVE SOME MEASURABLE
RAINFALL OVER THE MOUNTAINS AND FOOTHILLS LATE DAY WEDNESDAY. JUST
A TAD LESS FOR LATE DAY THURSDAY. THERE IS NOTHING OVER THE PLAINS
BOTH DAYS. FOR POPS WILL STICK WITH 20-30%S IN THE MOUNTAINS AND
FOOTHILLS LATE DAY WEDNESDAY AND LATE DAY THURSDAY. FOR
TEMPERATURES...WEDNESDAY`S HIGHS LOOK PRETTY CLOSE TO TODAY`S
EXPECTED READINGS. THURSDAY HIGHS COME UP 0-1.5 C FROM
WEDNESDAY`S. FOR THE LATER DAYS...FRIDAY THROUGH MONDAY...THE
UPPER RIDGE IS CENTERED OVER COLORADO ALL FOUR DAYS. MOISTURE
INCREASES SOMEWHAT...ESPECIALLY ON SUNDAY AND MONDAY. TEMPERATURES
DO STAY ABOVE NORMAL.
AVIATION...SIMILAR CONDITIONS AS THE PAST FEW DAYS WILL PREVAIL
TODAY WITH ISOLATED THUNDERSTORMS POSSIBLE BETWEEN 22Z AND 03Z. THE
STORMS WILL BE SHORT LIVED WITH BRIEF HEAVY RAIN...SMALL HAIL AND
WIND GUSTS TO 40 KNOTS POSSIBLE WITH THE STORMS. OUTSIDE OF
THUNDERSTORMS...LIGHT WINDS WILL PREVAIL TODAY.
HYDROLOGY...MOISTURE DECREASES A LITTLE TODAY...BUT THE INSTABILITY
WILL INCREASE. THE STORMS THAT DO FORM MAY HAVE A BETTER CHANCE OF
PRODUCING HEAVY. STORMS ARE EXPECT TO BE SHORT LIVED WITH UP TO ONE
INCH OF RAIN POSSIBLE WITH THE STRONGEST STORMS IN 20 MINUTES.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....RJK
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS TAUNTON MA
152 AM EDT TUE AUG 27 2013
.SYNOPSIS...
SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED THROUGH WEDNESDAY
AS A SERIES OF DISTURBANCES MOVE ACROSS NEW ENGLAND. DRY WEATHER
WILL FOLLOW LATER THIS WEEK WITH ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS POSSIBLE EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
2 AM UPDATE...
NOT MUCH CHANGE FROM PREVIOUS FORECAST. IMPRESSIVE SHORT WAVE OVER
NY STATE CONTINUES TO GENERATE WIDESPREAD SHOWERS WITH LOCALLY
HEAVY RAIN ACROSS MUCH OF NY INTO NEW ENGLAND. BULK OF RAIN MISSES
SOUTHEAST NH AND NORTHEAST MA OVERNIGHT. EARLIER DISCUSSION BELOW.
------------------------------------------------------------------
PWATS NEAR 2.0 INCHES WILL YIELD A LOW RISK OF MINOR POOR
DRAINAGE FLOODING OVERNIGHT IN THE URBAN AREAS. LATEST HRRR AND
12Z ECMWF SUGGEST STRONGEST FORCING FOR ASCENT ACROSS PA/NY AND
POSSIBLY INTO WESTERN MA AND CT GIVEN PROXIMITY OF LFQ OF UPPER
LEVEL JET STREAK...ENHANCING QG FORCING. THEREFORE HEAVIEST
RAINFALL LIKELY ACROSS WESTERN MA/CT AND POSSIBLY INTO RI.
RISK OF STRONG STORMS VERY LOW WITH INSTAB AND SHEAR OUT OF PHASE
WITH EACH OTHER...BEST INSTABILITY ALOFT ACROSS NORTHERN NEW
ENGLAND...WHILE STRONGEST WIND FIELD ALOFT ACROSS PA/NY/NJ NEAR
LFQ OF UPPER JET.
WARM AND MUGGY OVERNIGHT WITH DEW PTS IN THE M60S TO L70S
PRECLUDING TEMPS FROM FALLING MUCH.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
TUESDAY...
ANY LEFTOVER SHOWERS/SCT TSTMS WILL EXIT ACROSS THE S COAST DURING
THE MORNING. HAVE LEFT IN LOW LIKELY POPS THERE EARLY...THEN WILL
STEADILY IMPROVE TOWARD MIDDAY. HOWEVER...WILL STILL BE UNDER
CYCLONIC FLOW ALOFT...SO STILL COULD SEE WIDELY SCT SHOWERS OR AN
ISOLD TSTM MAINLY ACROSS INLAND AREAS WITH FAIRLY GOOD INSTABILITY
IN PLACE. ONLY PROBLEM FOR ANY STRONGER STORMS TO DEVELOP WILL BE
LACK OF SHEAR AND WINDS AT THE SURFACE AND ALOFT REMAIN LIGHT. MAY
SEE BRIEF HEAVY DOWNPOURS WITH ANY SHOWER OR STORM. HIGHS WILL
REACH THE LOWER-MID 80S...EXCEPT THE MID-UPPER 70S ALONG THE
IMMEDIATE COAST.
TUESDAY NIGHT...
LONG WAVE TROUGHING REMAINS JUST E OF THE REGION...KEEPING JUST
ENOUGH CYCLONIC FLOW IN PLACE TO TRY TO ROTATE SOME WIDELY SCT
SHOWERS OR EVEN AN ISOLD TSTM TOWARD THE E COAST. OTHERWISE...ANY
SHOWERS/TSTMS INLAND SHOULD END WITHIN AN HOUR OR SO OF SUNSET.
WITH MUGGY AIRMASS REMAINING IN PLACE...EXPECT LOWS ONLY IN THE
60S ALONG WITH PATCHY FOG DEVELOPING MAINLY AFTER MIDNIGHT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
HIGHLIGHTS...
* UNSETTLED WEATHER EXPECTED WED AND THU
* DRY AND INCREASINGLY WARM WEATHER END OF THE WEEK
* UNSETTLED WEATHER RETURNS EARLY NEXT WEEK
MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE BROAD SCALE THOUGH THERE
ARE DEFINITELY DISCREPANCIES IN THE DETAILS...PARTICULARLY DURING
THE UNSETTLED PERIODS OF WEATHER. THE WPC IS OPTING FOR A BLEND OF
THE GEFS AND THE ECMWF ENSEMBLE MEANS WHICH ARE IN THE MIDDLE OF THE
SOLUTION ENVELOPE WHILE THE RESPECTIVE OPERATIONAL MODELS ARE
TRENDING TO THE OUTSIDE. THAT BEING SAID...WILL TRY TO USE AS MUCH
OF THE WPC FORECAST AS POSSIBLE TO INCORPORATE THE ENSEMBLE MEANS.
A SERIES OF LOW PRESSURE CENTERS WILL TRAVEL ALONG OR JUST SOUTH OF
40 N LATITUDE WEDNESDAY AND INTO THE MARITIMES THURSDAY AS HIGH
PRESSURE BUILDS INTO SOUTHERN NEW ENGLAND. HIGH PRESSURE WILL BE
THE DOMINANT WEATHER FEATURE FRIDAY AND SATURDAY THEN MOVES
OFFSHORE...ALLOWING LOW PRESSURE TO MOVE INTO QUEBEC AND BRINGING A
COLD FRONT THROUGH SOUTHERN NEW ENGLAND MONDAY.
WEDNESDAY AND THURSDAY...ONE OR MORE LOW PRESSURE CENTERS WILL MOVE
SOUTH OF SOUTHERN NEW ENGLAND...CONTINUING THE UNSETTLED WEATHER
OVER THE AREA TODAY AND TUESDAY. TRICKY FORECAST FOR SEVERE STORM
POTENTIAL. WHILE THERE IS MORE LIFT ON WEDNESDAY WITH LOW PRESSURE
NEARER TO SOUTHERN NEW ENGLAND...THE BETTER SHEAR AND COOLER
TEMPERATURES ALOFT COME ON THURSDAY WITH PLENTY OF INSTABILITY
AROUND BOTH DAYS. WILL HAVE TO CONTINUE TO MONITOR THE FORECAST FOR
THIS TIME PERIOD. TEMPERATURES SHOULD BE RIGHT AROUND TO JUST BELOW
NORMAL FOR LATE AUGUST.
FRIDAY AND SATURDAY...HIGH PRESSURE BUILDS INTO THE REGION AND WITH
IT COMES WARMER TEMPERATURES AS WELL. SOUTHWESTERLY TO WESTERLY
DOWNSLOPING FLOW WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL
BRINGING ONE MORE SHOT OF SUMMER LIKE WEATHER TO THE AREA.
SUNDAY AND MONDAY...STRONG LOW PRESSURE MOVES THROUGH QUEBEC TO THE
MARITIMES BRINGING A COLD FRONT ACROSS SOUTHERN NEW ENGLAND MONDAY.
SHOWERS AND THUNDERSTORMS ARE POSSIBLE AHEAD OF THIS FRONT WITH THE
HEAT AND HUMIDITY STILL IN PLACE. MUCH OF THIS WILL DEPEND ON THE
SPEED OF THE FRONT...AMONG OTHER THINGS.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH TUESDAY NIGHT/...MODERATE CONFIDENCE.
IFR/LIFR IN RAIN SHOWERS ACROSS CT/RI AND SOUTH OF I-90 IN MA.
CONVERSELY VFR OVER NORTHEAST MA AND SOUTHEAST MA. RAIN SHIELD AND
LOW CIGS/VSBYS SLIDE SOUTHEAST TODAY WITH IMPROVING TO VFR FROM NW
TO SE AS THE DAY PROGRESSES. NEW SHOWERS/TSTMS WITH ISOLATED/WIDELY
SCATTERED IN AREAL COVERAGE ARE POSSIBLE ACROSS WESTERN CT/MA AND
SOUTHWEST NH THIS AFTERNOON. IFR IN LOW CLOUDS/VSBYS MAY LINGER MUCH
OF THE DAY OVER NANTUCKET/CAPE COD AND ISLANDS.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. HEAVIEST RAIN STAYS
SOUTHWEST OF TERMINAL.
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. IMPROVING WEATHER THIS
AFTERNOON.
OUTLOOK...WEDNESDAY THROUGH SATURDAY...
WEDNESDAY AND THURSDAY...MODERATE CONFIDENCE. MAINLY VFR.
MVFR/IFR CONDITIONS LIKELY IN ANY SHOWERS AND THUNDERSTORMS THAT
DEVELOP ALONG WITH POSSIBLE FOG WEDNESDAY NIGHT.
FRIDAY AND SATURDAY...HIGH CONFIDENCE. VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH MONDAY NIGHT/...HIGH CONFIDENCE.
HAVE KEPT SMALL CRAFTS THROUGH TUESDAY. SW WIND GUSTS UP TO 25
KT ACROSS THE SOUTHERN WATERS THROUGH AROUND MIDNIGHT WILL
DIMINISH. ALREADY NOTING SEAS UP TO 6 FT AT SEVERAL OF THE
SOUTHERN BUOYS WHICH WILL SLOWLY SUBSIDE TUESDAY.
WILL SEE INCREASING CHANCE FOR SHOWERS/TSTMS TONIGHT AS WEAK LOW
PRES MOVES TOWARD THE WATERS. WILL SEE REDUCED VSBYS IN ANY
PRECIP ALONG WITH PATCHY FOG DEVELOPING. VSBYS WILL IMPROVE BY
AROUND MIDDAY TUESDAY AS THE FOG DISSIPATES AND PRECIP MOVES
OFFSHORE. WILL LIKELY SEE FOG REDEVELOP TUE NIGHT.
OUTLOOK...WEDNESDAY THROUGH SATURDAY...
WHILE WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT CRITERIA FROM
MID WEEK THROUGH THE END OF THE WEEK...THERE IS POTENTIAL FOR
SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY. ALSO
VISIBILITIES MAY BE LIMITED WEDNESDAY NIGHT IN PATCHY FOG.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR
ANZ254>256.
SMALL CRAFT ADVISORY UNTIL 7 AM EDT THIS MORNING FOR ANZ235-
237.
&&
$$
SYNOPSIS...RLG/EVT
NEAR TERM...NOCERA/RLG/EVT
SHORT TERM...EVT
LONG TERM...RLG
AVIATION...NOCERA/RLG
MARINE...RLG/EVT
AREA FORECAST DISCUSSION
NWS MIAMI FL
847 PM EDT WED AUG 28 2013
.UPDATE...
ONLY CHANGES TO PREVIOUS FORECAST WERE DONE IN THE SHORT TERM...TO
ACCOUNT FOR THE PERSISTENT ACTIVITY ACROSS THE LAKE OKEECHOBEE
AREA AND SURROUNDING COMMUNITIES. LATEST HRRR RUN KEEPS THIS AREA WET
OVERNIGHT...WITH A DECREASE IN COVERAGE AFTER MIDNIGHT. 00Z
SOUNDING SHOWING A SLIGHTLY DRIER AIRMASS AT MID-LEVELS COMPARED
TO YESTERDAYS AND THIS MORNINGS OBSERVATIONS. THIS IS DUE TO THE COMBINATION
OF THE LOW PRESSURE WEAKENING WHILE MOVING NORTHEAST...ALLOWING
FOR A SOUTHWEST FLOW AT MID LEVELS TO BRING DRIER AIR TO THE AREA.
THIS IS CONSISTENT WITH CURRENT MODEL GUIDANCE AND FORECAST TREND.
&&
.PREV DISCUSSION... /ISSUED 804 PM EDT WED AUG 28 2013/
AVIATION...
COVERAGE OF SHRAS/TSRAS ASSOCIATED WITH A PERSISTENT H5 LOW HAS
SLOWLY DIMINISHED ACROSS THE AREA EARLY THIS EVENING AND IS NOW
RELEGATED TO THE INTERIOR AND LAKE OKEECHOBEE AREAS. ACTIVITY
SHOULD CONTINUE TO DECREASE IN COVERAGE THROUGH THE EVENING AND
IS NOT EXPECTED TO AFFECT THE TAF SITES. WINDS SHOULD BECOME LIGHT
AND VARIABLE OVERNIGHT BEFORE LIGHT EASTERLY FLOW RETURNS TOMORROW
FOR THE EAST COAST SITES. KAPF SHOULD SEE A GULF BREEZE DEVELOP
DURING THE EARLY AFTERNOON HOURS TOMORROW AND PENETRATE INLAND DUE
TO THE WEAKER EASTERLY FLOW.
PREV DISCUSSION... /ISSUED 224 PM EDT WED AUG 28 2013/
SHORT TERM (TONIGHT-FRIDAY NIGHT)...
THE LATEST MODEL GUIDANCE REMAINS IN DECENT AGREEMENT THROUGH THE
SHORT-TERM PERIOD AND INDICATES THE MID/UPPER LOW CURRENTLY OVERHEAD
THAT HAS LED TO THE ADDITIONAL CLOUD/RAINFALL COVERAGE WILL CONTINUE
TO INFLUENCE THE LOCAL WEATHER THROUGH THE BULK OF THE PERIOD AS IT
GRADUALLY LIFTS NNE OVER THE STATE WITHIN THE WEAKNESS IN THE RIDGE.
MODEL SOUNDINGS ACROSS THE LOCAL AREA SHOW THE DEEP LAYER FLOW
GRADUALLY SHIFTING TOWARD THE WEST TONIGHT THROUGH FRIDAY WITH THE
PRECIPITABLE WATER REMAINING AROUND AND JUST UNDER THE 2" MARK.
DECENT MID-LEVEL LAPSE RATES ACROSS THE AREA THURSDAY COULD RESULT
IN A FEW STRONG STORMS DEVELOPING PROVIDED ANY BREAKS IN THE CLOUD
COVERAGE ALLOWING FOR DESTABILIZATION. THIS COMBINED WITH THE DEEP
LAYER FLOW SHIFTING TO THE SW SHOULD FAVOR MUCH OF THE
AFTERNOON/EVENING DEVELOPMENT OVER THE EASTERN HALF OF THE PENINSULA
AND TOWARD THE EAST COAST EACH DAY. THE MAIN IMPACTS OR CONCERNS
WOULD BE MINOR FLOODING AND GUSTY WINDS IF THIS VERIFIES.
HOWEVER...UNCERTAINTY REMAINS HIGH AS THE LATEST HI-RES MODEL
REFLECTIVITIES FROM THE WRF SHOW MAINLY ISOLATED COVERAGE THROUGH
THIS TIME.
LONG TERM (SATURDAY-WEDNESDAY)...
CONDITIONS ARE EXPECTED TO TREND BACK TOWARD NORMAL THROUGH THE
WEEKEND AS UPPER HEIGHTS BEGIN TO RISE AND THE AFOREMENTIONED
MID/UPPER LOW LIFTS NORTH OF OUR LOCAL AREA. ANOTHER WEAK FRONTAL
BOUNDARY ASSOCIATED WITH AN UPPER TROUGH DEEPENING OVER THE EAST
COAST EARLY NEXT WEEK IS PROGGED TO ENTER THE STATE FROM THE NORTH
TUESDAY THROUGH THE MID-WEEK PERIOD. THESE FEATURES MAY BEGIN TO
SUPPORT ADDITIONAL RAIN CHANCES ACROSS THE STATE BY THE END OF THE
PERIOD IF THE EXTENDED GUIDANCE REMAINS PERSISTENT WITH THIS
SOLUTION.
MARINE...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH
THURSDAY AS AN UPPER LOW CONTINUES TO INFLUENCE THE LOCAL WEATHER.
MARINERS CAN EXPECT PERIODS WITH REDUCED VISIBILITIES...GUSTY
WINDS AND LOCALLY CHOPPIER CONDITIONS IN AND AROUND THIS ACTIVITY.
HIGH PRESSURE WILL BUILD BACK OVERHEAD THROUGH THE WEEKEND WITH
LIGHT WINDS CONTINUING.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 75 89 76 90 / 40 40 40 20
FORT LAUDERDALE 75 88 79 91 / 30 30 30 20
MIAMI 75 90 78 91 / 20 30 30 20
NAPLES 72 89 75 90 / 30 30 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...17/ERA
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
244 PM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* NO CONCERNS IN THE NEAR TERM.
* SHOWERS/TS POSSIBLE LATE THIS EVENING.
* FROPA LATE TONIGHT WITH WINDS TURNING THE NORTHWEST...AND
EVENTUALLY NORTHEAST EARLY WEDNESDAY MORNING.
* MVFR/IFR CEILINGS POSSIBLE EARLY WEDNESDAY MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 18Z...
HIGH LEVEL CIRRUS IS THE DOMINANT CLOUD COVER EARLY THIS AFTERNOON
WHILE SOUTHWEST WINDS GUST IN THE UPPER TEENS. THESE CURRENT
PREVAILING CONDITIONS WILL REMAIN THIS AFTERNOON AND FOR A
PORTION OF THE EARLY EVENING AS A TROUGH OF LOW PRESSURE AND
ASSOCIATED FRONTAL BOUNDARY APPROACH FROM THE NORTHWEST. AS THIS
SYSTEM APPROACHES...SHOWERS AND THUNDERSTORMS SHOULD DEVELOP ALONG
AND OUT AHEAD OF IT THIS EVENING. ALTHOUGH...WITH COVERAGE OF
THESE STORMS APPEARING TO BE SPOTTY...HAVE ONLY MADE MENTION OF VC
AT THIS TIME. THIS WILL LIKELY NEED TO BE REFINED AS THE TIME
DRAWS NEAR LATER THIS EVENING. WITH FROPA OVERNIGHT...EXPECT
SOUTHWEST WINDS TO FLOP OVER TO THE NORTHWEST AND THEN NORTH
NORTHEAST WEDNESDAY MORNING...WITH THESE WINDS TO THEN PREVAIL FOR
THE REMAINDER OF THE FORECAST PERIOD. CONTINUE TO MONITOR THE
POTENTIAL FOR LOW CEILINGS EARLY WEDNESDAY MORNING...POSSIBLY MVFR
AND EVEN IFR. THESE LOWER CEILINGS CURRENTLY RESIDE WELL TO THE
NORTH...BUT WILL HAVE THE POTENTIAL TO MOVE SOUTH DOWN THE LAKE
OVERNIGHT. IF THEY DO MAKE IT DOWN TO THE TERMINALS...EXPECT THEM
TO BE MORE TRANSIENT WITH ANY LOWER CEILINGS NOT EXPECTED TO BE
TOO LONG LASTING.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE WITH SHOWERS/TS TRENDS LATER THIS EVENING.
* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.
* LOW MEDIUM CONFIDENCE WITH POSSIBLE MVFR/IFR CEILINGS EARLY
WEDNESDAY MORNING.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...MVFR PSBL.
THURSDAY...SCHC SHRA/TSRA OVERNIGHT
FRIDAY AND SATURDAY...CHC SHRA/TSRA.
SUNDAY AND MONDAY...VFR.
JEE
&&
.MARINE...
242 PM CDT
A BROAD TROUGH STRETCHES ACROSS LAKE MICHIGAN THIS AFTERNOON WITH
GENERALLY SOUTHERLY WINDS ACROSS THE LAKE. AS THE TROUGH SAGS
SOUTHEAST OVER THE NEXT 24 HOURS...WINDS WILL TURN NORTHERLY AS HIGH
PRESSURE BUILDS OVER MINNESOTA AND WISCONSIN WITH WINDS PICKING BACK
UP INTO THE 15 TO 20 KT RANGE. WINDS THEN DIMINISH WEDNESDAY NIGHT
AND THURSDAY AS THE HIGH MOVES OVER LAKE MICHIGAN. ANOTHER FRONT
WILL PASS OVER LAKE MICHIGAN ON SUNDAY...WITH THE GRADIENT
TIGHTENING SUNDAY NIGHT AND MONDAY AS HIGH PRESSURE BUILDS OVER
ONTARIO. WINDS MAY INCREASE FOR A PERIOD INTO THE 30 KT RANGE
MONDAY...THEN DIMINISH MONDAY NIGHT INTO TUESDAY AS THE HIGH
BUILDS SOUTH OVER THE GREAT LAKES.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011 UNTIL 8 PM
TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
113 PM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* NO CONCERNS IN THE NEAR TERM.
* SHOWERS/TS POSSIBLE LATE THIS EVENING.
* FROPA LATE TONIGHT WITH WINDS TURNING THE NORTHWEST...AND
EVENTUALLY NORTHEAST EARLY WEDNESDAY MORNING.
* MVFR/IFR CEILINGS POSSIBLE EARLY WEDNESDAY MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 18Z...
HIGH LEVEL CIRRUS IS THE DOMINANT CLOUD COVER EARLY THIS AFTERNOON
WHILE SOUTHWEST WINDS GUST IN THE UPPER TEENS. THESE CURRENT
PREVAILING CONDITIONS WILL REMAIN THIS AFTERNOON AND FOR A
PORTION OF THE EARLY EVENING AS A TROUGH OF LOW PRESSURE AND
ASSOCIATED FRONTAL BOUNDARY APPROACH FROM THE NORTHWEST. AS THIS
SYSTEM APPROACHES...SHOWERS AND THUNDERSTORMS SHOULD DEVELOP ALONG
AND OUT AHEAD OF IT THIS EVENING. ALTHOUGH...WITH COVERAGE OF
THESE STORMS APPEARING TO BE SPOTTY...HAVE ONLY MADE MENTION OF VC
AT THIS TIME. THIS WILL LIKELY NEED TO BE REFINED AS THE TIME
DRAWS NEAR LATER THIS EVENING. WITH FROPA OVERNIGHT...EXPECT
SOUTHWEST WINDS TO FLOP OVER TO THE NORTHWEST AND THEN NORTH
NORTHEAST WEDNESDAY MORNING...WITH THESE WINDS TO THEN PREVAIL FOR
THE REMAINDER OF THE FORECAST PERIOD. CONTINUE TO MONITOR THE
POTENTIAL FOR LOW CEILINGS EARLY WEDNESDAY MORNING...POSSIBLY MVFR
AND EVEN IFR. THESE LOWER CEILINGS CURRENTLY RESIDE WELL TO THE
NORTH...BUT WILL HAVE THE POTENTIAL TO MOVE SOUTH DOWN THE LAKE
OVERNIGHT. IF THEY DO MAKE IT DOWN TO THE TERMINALS...EXPECT THEM
TO BE MORE TRANSIENT WITH ANY LOWER CEILINGS NOT EXPECTED TO BE
TOO LONG LASTING.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE WITH SHOWERS/TS TRENDS LATER THIS EVENING.
* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.
* LOW MEDIUM CONFIDENCE WITH POSSIBLE MVFR/IFR CEILINGS EARLY
WEDNESDAY MORNING.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...MVFR PSBL.
THURSDAY...SCHC SHRA/TSRA OVERNIGHT
FRIDAY AND SATURDAY...CHC SHRA/TSRA.
SUNDAY AND MONDAY...VFR.
JEE
&&
.MARINE...
225 AM CDT
LOW PRESSURE OVER SOUTH DAKOTA THIS MORNING WILL PASS OVER THE LAKE
TODAY WITH ITS COLD FRONT SLIDING DOWN THE LAKE TONIGHT. AS SUCH
GUSTY SW WINDS ARE ONCE AGAIN EXPECTED OVER THE SOUTHERN HALF OF THE
LAKE TODAY WITH LIGHTER EAST WINDS OVER THE NORTHERN HALF. WINDS
TURN NW TO N BEHIND THE FRONT TONIGHT THEN AS THE HIGH SETTLES IN
OVER THE REGION...WINDS BECOME LIGHT AND VARIABLE. THE HIGH SHIFTS
EAST THURSDAY NIGHT WITH WINDS BECOMING SOUTH ON FRIDAY. LIGHT
WINDS ARE EXPECTED THROUGH THE END OF THIS WEEK...BUT A STRONG LOW
FORMS OVER SASKATCHEWAN FRIDAY NIGHT. GUIDANCE SUGGESTS THE LOW
WILL PASS NORTH OF LAKE MICHIGAN BUT STRONG NW WINDS ARND 30 KT ARE
EXPECTED BEHIND THE LOWS COLD FRONT SUNDAY NIGHT INTO MONDAY
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011 UNTIL 8 PM
TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1110 AM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* NO CONCERNS IN THE NEAR TERM.
RODRIGUEZ
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE IS OVER THE SOUTHEAST US WHILE LOW PRESSURE IS OVER
EASTERN SD/SOUTHERN MN. THE LOW PRESSURE WILL TRACK ACROSS MN AND
WI TODAY BEFORE DRIFTING OVER LAKE MICHIGAN AND MI THIS EVENING/TONIGHT.
HIGH LEVEL CLOUD COVER FROM A DYING COMPLEX OVER MI HAS SPREAD
ACROSS THE REGION AND WE MAY GET ANOTHER ROUND OF HIGH LEVEL
CLOUDS FROM A SECOND CONVECTIVE SYSTEM OVER NORTHERN WI.
SW WIND GUSTS WILL ONCE AGAIN INCREASE BY MID MORNING WITH
SLIGHTLY STRONGER SUSTAINED SPEEDS THAN YESTERDAY...ARND 12KT.
GUSTS WILL BE ARND 18KT WITH OCNL GUSTS ARND 20KT ESPECIALLY LATE
THIS AFTN. GUSTS DIMINISH THIS EVENING AS THE LOWS COLD FRONT
APPROACHES FROM THE NORTH. THINKING WINDS WILL BEGIN TO VEER TO
THE NW LATE TONIGHT BECOMING N TO NNE TOMORROW MORNING.
FOR PRECIP...GUIDANCE CONTINUES TO INDICATE ISOL-SCT SHRA/TSRA
WILL DEVELOP TO THE NORTH AND EAST OF THE TERMINALS THIS EVENING
AND OVERNIGHT. THEREFORE KEPT THE TAFS DRY. IF STORMS WERE TO
REACH ANY OF THE TERMINALS...IT NOW LOOKS LIKE GYY WOULD BE THE
BEST BET.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN SHRA/TSRA TRENDS AROUND THE TERMINALS
TONIGHT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...MVFR PSBL.
THURSDAY...SCHC SHRA/TSRA OVERNIGHT
FRIDAY AND SATURDAY...CHC SHRA/TSRA.
SUNDAY AND MONDAY...VFR.
JEE
&&
.MARINE...
225 AM CDT
LOW PRESSURE OVER SOUTH DAKOTA THIS MORNING WILL PASS OVER THE LAKE
TODAY WITH ITS COLD FRONT SLIDING DOWN THE LAKE TONIGHT. AS SUCH
GUSTY SW WINDS ARE ONCE AGAIN EXPECTED OVER THE SOUTHERN HALF OF THE
LAKE TODAY WITH LIGHTER EAST WINDS OVER THE NORTHERN HALF. WINDS
TURN NW TO N BEHIND THE FRONT TONIGHT THEN AS THE HIGH SETTLES IN
OVER THE REGION...WINDS BECOME LIGHT AND VARIABLE. THE HIGH SHIFTS
EAST THURSDAY NIGHT WITH WINDS BECOMING SOUTH ON FRIDAY. LIGHT
WINDS ARE EXPECTED THROUGH THE END OF THIS WEEK...BUT A STRONG LOW
FORMS OVER SASKATCHEWAN FRIDAY NIGHT. GUIDANCE SUGGESTS THE LOW
WILL PASS NORTH OF LAKE MICHIGAN BUT STRONG NW WINDS ARND 30 KT ARE
EXPECTED BEHIND THE LOWS COLD FRONT SUNDAY NIGHT INTO MONDAY
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011 UNTIL 8 PM
TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
909 AM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* NO CONCERNS IN THE NEAR TERM.
RODRIGUEZ
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE IS OVER THE SOUTHEAST US WHILE LOW PRESSURE IS OVER
EASTERN SD/SOUTHERN MN. THE LOW PRESSURE WILL TRACK ACROSS MN AND
WI TODAY BEFORE DRIFTING OVER LAKE MICHIGAN AND MI THIS EVENING/TONIGHT.
HIGH LEVEL CLOUD COVER FROM A DYING COMPLEX OVER MI HAS SPREAD
ACROSS THE REGION AND WE MAY GET ANOTHER ROUND OF HIGH LEVEL
CLOUDS FROM A SECOND CONVECTIVE SYSTEM OVER NORTHERN WI.
SW WIND GUSTS WILL ONCE AGAIN INCREASE BY MID MORNING WITH
SLIGHTLY STRONGER SUSTAINED SPEEDS THAN YESTERDAY...ARND 12KT.
GUSTS WILL BE ARND 18KT WITH OCNL GUSTS ARND 20KT ESPECIALLY LATE
THIS AFTN. GUSTS DIMINISH THIS EVENING AS THE LOWS COLD FRONT
APPROACHES FROM THE NORTH. THINKING WINDS WILL BEGIN TO VEER TO
THE NW LATE TONIGHT BECOMING N TO NNE TOMORROW MORNING.
FOR PRECIP...GUIDANCE CONTINUES TO INDICATE ISOL-SCT SHRA/TSRA
WILL DEVELOP TO THE NORTH AND EAST OF THE TERMINALS THIS EVENING
AND OVERNIGHT. THEREFORE KEPT THE TAFS DRY. IF STORMS WERE TO
REACH ANY OF THE TERMINALS...IT NOW LOOKS LIKE GYY WOULD BE THE
BEST BET.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN SHRA/TSRA TRENDS AROUND THE TERMINALS
TONIGHT.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...MVFR PSBL.
THURSDAY...SCHC SHRA/TSRA OVERNIGHT
FRIDAY AND SATURDAY...CHC SHRA/TSRA.
SUNDAY AND MONDAY...VFR.
JEE
&&
.MARINE...
225 AM CDT
LOW PRESSURE OVER SOUTH DAKOTA THIS MORNING WILL PASS OVER THE LAKE
TODAY WITH ITS COLD FRONT SLIDING DOWN THE LAKE TONIGHT. AS SUCH
GUSTY SW WINDS ARE ONCE AGAIN EXPECTED OVER THE SOUTHERN HALF OF THE
LAKE TODAY WITH LIGHTER EAST WINDS OVER THE NORTHERN HALF. WINDS
TURN NW TO N BEHIND THE FRONT TONIGHT THEN AS THE HIGH SETTLES IN
OVER THE REGION...WINDS BECOME LIGHT AND VARIABLE. THE HIGH SHIFTS
EAST THURSDAY NIGHT WITH WINDS BECOMING SOUTH ON FRIDAY. LIGHT
WINDS ARE EXPECTED THROUGH THE END OF THIS WEEK...BUT A STRONG LOW
FORMS OVER SASKATCHEWAN FRIDAY NIGHT. GUIDANCE SUGGESTS THE LOW
WILL PASS NORTH OF LAKE MICHIGAN BUT STRONG NW WINDS ARND 30 KT ARE
EXPECTED BEHIND THE LOWS COLD FRONT SUNDAY NIGHT INTO MONDAY
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011 UNTIL 8 PM
TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
703 AM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* WINDS BECOMING N TO NNE ARND 8KT WEDNESDAY MORNING.
JEE
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE IS OVER THE SOUTHEAST US WHILE LOW PRESSURE IS OVER
EASTERN SD/SOUTHERN MN. THE LOW PRESSURE WILL TRACK ACROSS MN AND
WI TODAY BEFORE DRIFTING OVER LAKE MICHIGAN AND MI THIS EVENING/TONIGHT.
HIGH LEVEL CLOUD COVER FROM A DYING COMPLEX OVER MI HAS SPREAD
ACROSS THE REGION AND WE MAY GET ANOTHER ROUND OF HIGH LEVEL
CLOUDS FROM A SECOND CONVECTIVE SYSTEM OVER NORTHERN WI.
SW WIND GUSTS WILL ONCE AGAIN INCREASE BY MID MORNING WITH
SLIGHTLY STRONGER SUSTAINED SPEEDS THAN YESTERDAY...ARND 12KT.
GUSTS WILL BE ARND 18KT WITH OCNL GUSTS ARND 20KT ESPECIALLY LATE
THIS AFTN. GUSTS DIMINISH THIS EVENING AS THE LOWS COLD FRONT
APPROACHES FROM THE NORTH. THINKING WINDS WILL BEGIN TO VEER TO
THE NW LATE TONIGHT BECOMING N TO NNE TOMORROW MORNING.
FOR PRECIP...GUIDANCE CONTINUES TO INDICATE ISOL-SCT SHRA/TSRA
WILL DEVELOP TO THE NORTH AND EAST OF THE TERMINALS THIS EVENING
AND OVERNIGHT. THEREFORE KEPT THE TAFS DRY. IF STORMS WERE TO
REACH ANY OF THE TERMINALS...IT NOW LOOKS LIKE GYY WOULD BE THE
BEST BET.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN SCT SHRA/TSRA THIS EVENING BTWN 00 AND
06Z...BUT MEDIUM-HIGH CONFIDENCE IN SHRA/TSRA REMAINING OUTSIDE
OF TERMINALS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...MVFR PSBL.
THURSDAY...SCHC SHRA/TSRA OVERNIGHT
FRIDAY AND SATURDAY...CHC SHRA/TSRA.
SUNDAY AND MONDAY...VFR.
JEE
&&
.MARINE...
225 AM CDT
LOW PRESSURE OVER SOUTH DAKOTA THIS MORNING WILL PASS OVER THE LAKE
TODAY WITH ITS COLD FRONT SLIDING DOWN THE LAKE TONIGHT. AS SUCH
GUSTY SW WINDS ARE ONCE AGAIN EXPECTED OVER THE SOUTHERN HALF OF THE
LAKE TODAY WITH LIGHTER EAST WINDS OVER THE NORTHERN HALF. WINDS
TURN NW TO N BEHIND THE FRONT TONIGHT THEN AS THE HIGH SETTLES IN
OVER THE REGION...WINDS BECOME LIGHT AND VARIABLE. THE HIGH SHIFTS
EAST THURSDAY NIGHT WITH WINDS BECOMING SOUTH ON FRIDAY. LIGHT
WINDS ARE EXPECTED THROUGH THE END OF THIS WEEK...BUT A STRONG LOW
FORMS OVER SASKATCHEWAN FRIDAY NIGHT. GUIDANCE SUGGESTS THE LOW
WILL PASS NORTH OF LAKE MICHIGAN BUT STRONG NW WINDS ARND 30 KT ARE
EXPECTED BEHIND THE LOWS COLD FRONT SUNDAY NIGHT INTO MONDAY
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011...NOON
TUESDAY TO 8 PM TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
400 AM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* SLIGHT CHANCE FOR SCT SHRA/TSRA THIS EVENING.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS OVER THE SOUTHEAST US WHILE LOW PRESSURE IS OVER
SOUTH DAKOTA. THE LOW PRESSURE WILL TRACK ACROSS MN AND WI TODAY
BEFORE DRIFTING SOUTHEAST OVER NORTHERN IL AND IN THIS EVENING AND
TONIGHT. CURRENTLY HIGH LEVEL CLOUD COVER IS SINKING SOUTH FROM A
CONVECTIVE COMPLEX OVER NORTHERN WI...BUT THE CONVECTION WILL
REMAIN WELL NORTH OF THE TERMINALS.
SW WIND GUSTS WILL ONCE AGAIN INCREASE BY MID MORNING WITH
SLIGHTLY STRONGER SUSTAINED SPEEDS THAN YESTERDAY...ARND 12KT.
GUSTS WILL BE ARND 18KT WITH OCNL GUSTS ARND 20KT ESPECIALLY LATE
THIS AFTN. GUSTS DIMINISH THIS EVENING AS THE LOWS COLD FRONT
APPROACHES FROM THE NORTH. FOR WINDS...THINKING WINDS WILL BEGIN
TO VEER TO THE NW LATE TONIGHT ARND 10Z.
FOR PRECIP...GUIDANCE SUGGESTS ISOL-SCT SHRA/TSRA WILL DEVELOP
AROUND THE EASTERN TERMINALS BTWN 00 AND 06Z BUT STILL THINKING
THE MAJORITY OF SHRA/TSRA WILL REMAIN NORTH AND EAST OF THE
TERMINALS CLOSER TO THE FORCING ALOFT. AS SUCH KEPT THE TAFS DRY
FOR NOW...BUT THAT MAY CHANGE IF SHRA/TSRA ARE MORE PLENTIFUL THAN
EXPECTED.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN SCT SHRA/TSRA THIS EVENING BTWN 00 AND
06Z...BUT MEDIUM CONFIDENCE IN SHRA/TSRA REMAINING OUTSIDE OF
TERMINALS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR.
THURSDAY...SLIGHT CHANCE TSRA OVERNIGHT.
FRIDAY...SLIGHT CHANCE TSRA.
SATURDAY AND SUNDAY...VFR.
MDB
&&
.MARINE...
225 AM CDT
LOW PRESSURE OVER SOUTH DAKOTA THIS MORNING WILL PASS OVER THE LAKE
TODAY WITH ITS COLD FRONT SLIDING DOWN THE LAKE TONIGHT. AS SUCH
GUSTY SW WINDS ARE ONCE AGAIN EXPECTED OVER THE SOUTHERN HALF OF THE
LAKE TODAY WITH LIGHTER EAST WINDS OVER THE NORTHERN HALF. WINDS
TURN NW TO N BEHIND THE FRONT TONIGHT THEN AS THE HIGH SETTLES IN
OVER THE REGION...WINDS BECOME LIGHT AND VARIABLE. THE HIGH SHIFTS
EAST THURSDAY NIGHT WITH WINDS BECOMING SOUTH ON FRIDAY. LIGHT
WINDS ARE EXPECTED THROUGH THE END OF THIS WEEK...BUT A STRONG LOW
FORMS OVER SASKATCHEWAN FRIDAY NIGHT. GUIDANCE SUGGESTS THE LOW
WILL PASS NORTH OF LAKE MICHIGAN BUT STRONG NW WINDS ARND 30 KT ARE
EXPECTED BEHIND THE LOWS COLD FRONT SUNDAY NIGHT INTO MONDAY
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011...NOON
TUESDAY TO 8 PM TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
324 AM CDT TUE AUG 27 2013
.DISCUSSION...
324 AM CDT
FORECAST CHALLENGES THIS MORNING INCLUDE TODAY`S HEAT...THEN
TEMPS/POPS AS WE TEETER ON THE PERIPHERY OF UNSEASONABLY STRONG LATE
SUMMER UPPER HOT DOME INTO THE WEEKEND.
THE CARCASS OF SUNDAY NIGHT`S MCS PROVIDED A SHROUD OF FAIRLY DENSE
CIRRUS OVER THE AREA MONDAY AFTERNOON HOLDING TEMPS ABOUT 2-4F
COOLER THAN EXPECTED. ONCE AGAIN EARLY THIS MORNING MCS ACTIVITY IS
FESTERING ABOUT TO OUR NORTH ON THE PERIPHERY OF THE UPPER RIDGE.
CONVECTIVELY ENHANCED VORT DRIVING THIS MCS APPEARS TO BE PUSHING
INTO NORTHERN PORTIONS OF LAKE MICHIGAN ALREADY WITH BACK EDGE OF
CIRRUS SHIELD MOVING INTO NW WISCONSIN. HRRR SEEMS TO HAVE A GOOD
HANDLE ON ONGOING CONVECTIVE TRENDS AND IT...ALONG WITH THE MAJORITY
OF THE OTHER GUIDANCE...SUGGESTS THAT TODAY`S CIRRUS DEBRIS WILL
CLEAR OUT BY EARLY AFTERNOON AND ALLOW FOR STRONG HEATING TO TAKE
PLACE...ESPECIALLY NORTHWESTERN CWA. LOW LEVEL THERMAL RIDGE
MOVING INTO THE AREA WITH 925MB TEMPS PROGGED TO RISE TO 26-28C
NORTHWESTERN CWA WHICH WOULD EASILY SUPPORT MIDDLE IF NOT UPPER
90S. IN THE PAST HOUR CONVECTION HAS FLARED OVER NORTHEAST MINNESOTA
WHICH IS CONCERNING AS 850-300MB THICKNESS SUGGESTS THAT COULD SINK
SOUTHWARD AND SPREAD MORE CIRRUS ACROSS THE AREA TODAY.
GIVEN POTENTIAL FOR DEBRIS CLOUDINESS TO LINGER AGAIN TODAY SPLIT
THE DIFFERENCE FOR HIGHS BETWEEN WHAT PROGGED 925MB TEMPS WOULD
SUPPORT AND WHAT CLIMO INFLUENCED MOS NUMBERS FORECAST. ASSUMING
DEWPOINTS DON`T MIX OUT AND ASSUMING CIRRUS CLEARS OUT THEN WE WOULD
GET CLOSE TO THE 105F HEAT INDEX ADVISORY CRITERIA THIS AFTERNOON
NORTH/NORTHWEST AREAS. GIVEN A FORECAST OF CONDITIONS NOT MEETING
CRITERIA AND LOW CONFIDENCE IN THEM EVEN GETTING AS BAD AS I HAVE IN
THE GRIDS...WOULD NOT NORMALLY ISSUE AN ADVISORY...BUT WITH
HEADLINES OUT FOR AREAS NORTH/WEST OF OUR CWA AND POTENTIAL FOR NEAR
RECORD HIGHS DECIDED TO MAKE THE W/W/A MAP PRETTY AND HOIST AN
ADVISORY FOR NORTH CENTRAL ILLINOIS. IF TRENDS THIS MORNING SUGGEST
THAT CIRRUS WONT BE A BIG DEAL THEN DAY SHIFT COULD CONSIDER
EXTENDING THE ADVISORY FARTHER EAST INTO THE CHICAGO AREA.
ANOTHER SHORTWAVE OVER THE EASTERN DAKOTAS THIS MORNING IS PROGGED
TO RIDE THE RIM OF THE RIDGE EAST INTO WISCONSIN THIS AFTERNOON AND
WILL PROBABLY RE-IGNITE THUNDERSTORMS TO OUR NORTH THIS AFTERNOON
WITH THESE STORMS POTENTIALLY CLIPPING OUR NORTHERN AND NORTHEASTERN
CWA THIS EVENING AS THE MOVE SOUTHEASTWARD. MODERATELY STRONG MID
LEVEL FLOW AND FAIRLY STRONG INSTABILITY (ASSUMING TDS DONT MIX OUT)
COULD SUPPORT A LOW END SEVERE THREAT WITH ANY STORMS THAT DO
MEANDER INTO OUR CWA TONIGHT.
LAKE ENHANCED COLD FRONT WILL MOVE INTO THE CWA EARLY WEDNESDAY
MORNING PROGRESSING SOUTHWARD INTO OUR SOUTHERN CWA BY AFTERNOON.
BETTER FORCING ALOFT SHOULD REMAIN TO OUR EAST BUT AM CONCERNED THAT
MOISTURE/INSTABILITY POOLING AND LOW LEVEL CONVERGENCE ALONG THE
FRONT COULD BE ENOUGH TO KICK OFF A THUNDERSTORM WEDNESDAY
AFTERNOON. SLIGHTLY COOLER AIR MASS WILL FILTER IN BEHIND THE
FRONT...WITH COOLING MOST NOTICEABLE NEAR LAKE MICHIGAN. AHEAD OF THE
FRONT WILL BE ANOTHER STEAMY DAY AND WITH BETTER DEWPOINT POOLING
COULD ACTUALLY END UP BEING HOTTER/MORE HUMID IN OUR SOUTHERN CWA
TOMORROW THAN TODAY...BUT THAT WILL HINGE ON THE AMOUNT OF
CLOUDINESS SOMETHING WHICH WILL BE MORE EASILY DIAGNOSED TONIGHT.
LOW LEVEL BAROCLINIC ZONE HANGS UP IN THE NEIGHBORHOOD THROUGH THE
END OF THE WEEK WITH WEAK NORTHWEST FLOW IMPULSES LIKELY TO RIPPLE
AROUND THE PERIPHERY OF THE HEAT DOME MEANS AT LEAST SOME POTENTIAL
FOR THUNDERSTORMS TONIGHT UNTIL STRONG COLD FRONT MOVES THROUGH THIS
WEEKEND. HAVE KEPT FORECAST DRY FOR NOW WEDNESDAY NIGHT THROUGH
THURSDAY BUT NW FLOW`S LIKE THIS ARE NOTORIOUS FOR PRODUCING
"SURPRISES" SO STAY TUNED!
HEADING INTO THE SECOND HALF OF THE LABOR DAY WEEKEND THE DIFFERENCE
BETWEEN THE 27/00Z RUN OF THE ECMWF WHEN COMPARED TO THE 25/12Z RUN
IS ABOUT AS DRAMATIC I`VE EVER SEEN IN THE WARM SEASON. FOR DAYS
MEDIUM RANGE MODELS HAD BEEN ADVERTISING RECORD BREAKING HEAT AND
NOW AFTER STARTING TO TREND SHARPLY COLDER WITH THE 26/12Z RUN THE
LATEST ECMWF NOW FORECASTS NEAR RECORD COLD TEMPERATURES BY MONDAY
WITH H8 TEMPS NEARING 0C! THE REMAINDER OF THE MEDIUM RANGE MODELS
HAVE BEEN TRENDING TOWARD THIS EARLIER FROPA/STRONG COLD PUSH
SOLUTION BUT STILL LAG WELL BEHIND THE UNSEASONABLY COLD ECMWF. IF
ECMWF WERE TO VERIFY WITH THIS INTENSE COOL SNAP THEN OUR FORECAST
WILL LIKELY TAKE A COUPLE MORE CYCLES TO CATCH UP WITH SUCH AN
ABRUPT CHANGE BUT HAVE TRENDED TEMPS DOWN SIGNIFICANTLY FROM THE
INITIALIZED ALLBLEND GUIDANCE...THOUGH IF LATEST EC VERIFIES HIGHS
MONDAY WOULD LIKELY BE IN THE 60S! NEEDLESS TO SAY FORECAST
CONFIDENCE IN THIS TIME PERIOD WILL REMAIN LOW UNTIL WE BEGIN TO SEE
MODELS CONVERGE ON A SOLUTION AND REMAIN MORE STABLE FROM RUN TO RUN.
IZZI
&&
.CLIMATE...
HERE ARE THE RECORD HIGHS FOR TUESDAY...
CHICAGO ROCKFORD
TUESDAY 97 (1973) 97 (1953)
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SLIGHT CHANCE FOR SCT SHRA/TSRA THIS EVENING.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS OVER THE SOUTHEAST US WHILE LOW PRESSURE IS OVER
SOUTH DAKOTA. THE LOW PRESSURE WILL TRACK ACROSS MN AND WI TODAY
BEFORE DRIFTING SOUTHEAST OVER NORTHERN IL AND IN THIS EVENING AND
TONIGHT. CURRENTLY HIGH LEVEL CLOUD COVER IS SINKING SOUTH FROM A
CONVECTIVE COMPLEX OVER NORTHERN WI...BUT THE CONVECTION WILL
REMAIN WELL NORTH OF THE TERMINALS.
SW WIND GUSTS WILL ONCE AGAIN INCREASE BY MID MORNING WITH
SLIGHTLY STRONGER SUSTAINED SPEEDS THAN YESTERDAY...ARND 12KT.
GUSTS WILL BE ARND 18KT WITH OCNL GUSTS ARND 20KT ESPECIALLY LATE
THIS AFTN. GUSTS DIMINISH THIS EVENING AS THE LOWS COLD FRONT
APPROACHES FROM THE NORTH. FOR WINDS...THINKING WINDS WILL BEGIN
TO VEER TO THE NW LATE TONIGHT ARND 10Z.
FOR PRECIP...GUIDANCE SUGGESTS ISOL-SCT SHRA/TSRA WILL DEVELOP
AROUND THE EASTERN TERMINALS BTWN 00 AND 06Z BUT STILL THINKING
THE MAJORITY OF SHRA/TSRA WILL REMAIN NORTH AND EAST OF THE
TERMINALS CLOSER TO THE FORCING ALOFT. AS SUCH KEPT THE TAFS DRY
FOR NOW...BUT THAT MAY CHANGE IF SHRA/TSRA ARE MORE PLENTIFUL THAN
EXPECTED.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN SCT SHRA/TSRA THIS EVENING BTWN 00 AND
06Z...BUT MEDIUM CONFIDENCE IN SHRA/TSRA REMAINING OUTSIDE OF
TERMINALS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR.
THURSDAY...SLIGHT CHANCE TSRA OVERNIGHT.
FRIDAY...SLIGHT CHANCE TSRA.
SATURDAY AND SUNDAY...VFR.
MDB
&&
.MARINE...
225 AM CDT
LOW PRESSURE OVER SOUTH DAKOTA THIS MORNING WILL PASS OVER THE LAKE
TODAY WITH ITS COLD FRONT SLIDING DOWN THE LAKE TONIGHT. AS SUCH
GUSTY SW WINDS ARE ONCE AGAIN EXPECTED OVER THE SOUTHERN HALF OF THE
LAKE TODAY WITH LIGHTER EAST WINDS OVER THE NORTHERN HALF. WINDS
TURN NW TO N BEHIND THE FRONT TONIGHT THEN AS THE HIGH SETTLES IN
OVER THE REGION...WINDS BECOME LIGHT AND VARIABLE. THE HIGH SHIFTS
EAST THURSDAY NIGHT WITH WINDS BECOMING SOUTH ON FRIDAY. LIGHT
WINDS ARE EXPECTED THROUGH THE END OF THIS WEEK...BUT A STRONG LOW
FORMS OVER SASKATCHEWAN FRIDAY NIGHT. GUIDANCE SUGGESTS THE LOW
WILL PASS NORTH OF LAKE MICHIGAN BUT STRONG NW WINDS ARND 30 KT ARE
EXPECTED BEHIND THE LOWS COLD FRONT SUNDAY NIGHT INTO MONDAY
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HEAT ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011...NOON
TUESDAY TO 8 PM TUESDAY.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1140 AM EDT TUE AUG 27 2013
.SYNOPSIS...
ISSUED AT 1140 AM EDT TUE AUG 27 2013
A FRONTAL BOUNDARY WILL IMPACT THE REGION OVER THE NEXT 24 TO 36
HOURS. ALONG AND NORTH OF IT...CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL EXIST INTO TONIGHT...ESPECIALLY ACROSS MUCH OF
LOWER MICHIGAN INTO PARTS OF NORTHERN INDIANA AND NORTHWESTERN
OHIO. SOUTH OF THE FRONT...HOT AND HUMID CONDITIONS WILL PREVAIL
WITH LITTLE CHANCE OF RAIN.
&&
.UPDATE...
ISSUED AT 1140 AM EDT TUE AUG 27 2013
NO SIG CHANGES TO FORECAST PLANNED AT THIS TIME.
FOCUS OF FORECAST INTO THIS AFTERNOON WILL BE ON 2ND COMPLEX OF
SHOWERS/STORMS MOVING INTO LWR MI AND SEVERAL OUTFLOW BOUNDARIES
ACROSS THE REGION.
AREA OF SHOWERS AND A FEW STORMS MOVING INTO NW LWR MICHIGAN WAS
SHOWING SIGNS OF WEAKENING PER LATEST RADAR TRENDS AND WARMING
CLOUD TOPS. THIS SHOULD CONTINUE TO TRACK SE AND REMAIN GENERALLY
NE OF THE AREA FOLLWOWING THE EDGE OF THE THETA E RIDGE FROM
MUSKEGON TOWARDS ANN ARBOR. HRRR HAS BEEN SPORADICALLY INDICATING
SOME ADDITIONAL DEVELOPMENT ON THE SW FLANK OF THIS AREA THAT
WOULD CLIP NE AREAS BUT LATEST RUNS HAVE BACKED OFF. MAIN FOCUS
MAY END UP BEING ASSOCIATED OUTFLOW DROPPING SE ACROSS
CENTRAL/SOUTHERN WISCONSIN. THIS WILL ARRIVE IN THE AREA THIS
AFTERNOON AS PEAK HEATING IS UNDERWAY. AT THIS POINT..CAN`T
JUSTIFY ANY POPS CHANGES IN EITHER DIRECTION AS MUCH LIKE
YESTERDAY THERE APPEAR TO BE NO OVERALL EFFECT ON SFC FLOW OR LIFT
PER OBSERVATIONS INDICATING NO CONVERGENCE OR EVEN CLOUD COVER
ASSOCIATED WITH IT.
IN TERMS OF TEMPS...SLIGHT LOWERING OF TEMPS MAY BE NEEDED NE BUT
WITH SKIES TRYING TO CLEAR OUT AND MAIN PUSH OF NEXT ROUND OF
CONVECTION LIKELY STAYING FURTHER NORTH...MAY BE ABLE TO SQUEEZE
UP MID/UPR 80S YET.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 441 AM EDT TUE AUG 27 2013
CHALLENGES TODAY AND TONIGHT CENTER AROUND DEVELOPMENT...TIMING...
LOCATION AND SEVERITY OF THUNDERSTORMS. THUNDERSTORMS HAVE BEEN
FORMING AND TRACKING OVERNIGHT ALONG A LOW LEVEL THETA E RIDGE WHERE
THETA E CONVERGENCE HAS BEEN OCCURRING. AN EMBEDDED SHORT WAVE WILL
TOP THE RIDGE EARLY TODAY AND WILL DESCENT SOUTHEAST ACROSS THE
WESTERN GREAT LAKES REGION. A NUMBER OF FACTOR SHOULD COME TOGETHER
FOR THUNDERSTORMS AS LOW LEVEL THETA E INCREASES AHEAD OF A WEAK
FRONT. ALTHOUGH MID LEVEL LAPSE RATES GENERALLY UNFAVORABLE FOR
CONVECTION...SOME SUPPORT FROM AN EXIT REGION OF AN UPPER LEVEL
JET...LOW LEVEL CONVERGENCE...AND FAVORABLE LOW LEVEL INSTABILITY
SHOULD AID IN STORM DEVELOPMENT. STRONG TO POSSIBLY SEVERE STORMS
SHOULD OCCUR ESPECIALLY OVER FAR NORTH AND NORTHEAST AREAS INCLUDE
COLDWATER AND HILLSDALE. OTHERWISE...KEPT TEMPERATURES HOT
TODAY...BACKED OFF A LITTLE WITH HIGHS OVER FAR NORTHEAST AREAS
WHERE CLOUDS AND STORMS MAY KEEP TEMPERATURES FROM REACHING 90
DEGREES.
&&
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 441 AM EDT TUE AUG 27 2013
A SHEARED VORTICITY MAXIMUM WILL CONTINUE TO TOP PERSISTENT LONGWAVE
UPPER RIDGE ACROSS CENTRAL CONUS INTO WEDNESDAY MORNING...ALLOWING
FOR SLIGHT DAMPENING OF MID LEVEL HEIGHTS ACROSS THE SOUTHERN GREAT
LAKES. MAINTENANCE OF UPPER LEVEL RIDGE AXIS POSITION...AND EVEN
SLIGHT RETROGRESSION INTO WEDNESDAY MORNING WILL ALLOW FOR A MORE
FAVORABLE MCS TRACK INTO ESPECIALLY NORTHEAST PORTIONS OF THE AREA.
AXIS OF MORE ENHANCED LOW LEVEL MOISTURE POOLING (PWATS AROUND 2
INCHES) WILL ALSO BE DRAWN SOUTHWARD WITH THE COOL FRONT EARLY
WEDNESDAY ENHANCING EARLY MORNING PRECIP CHANCES.
DRYING TREND EXPECTED BY MID MORNING WEDNESDAY WITH LOW CONFIDENCE
ON MESOSCALE DETAILS FOR REMAINDER OF THE DAY GIVEN IMPACTS FROM
MORNING CLOUDS AND POTENTIAL PRECIP. STRONGER MID LEVEL SHORT WAVE
WILL LIKELY DROP SOUTHEAST INTO THE LOWER OHIO VALLEY DURING THE
AFTERNOON WITH ANY ADDITIONAL UPSTREAM MID LEVEL FORCING HARD TO
LATCH ONTO AT THIS FORECAST DISTANCE AND LIKELY WEAK IN NATURE.
PERSISTENCE OF MID/UPPER RIDGE WILL ALSO KEEP SOME RATHER WEAK MID
LEVEL LAPSE RATES IN PLACE ACROSS THE REGION. PRESENCE OF POOLED
FRONTAL MOISTURE SHOULD ALLOW FOR WEAK TO NO SBCIN IN THE
AFTERNOON...BUT RESIDUAL CONVECTIVE DEBRIS AND LOW LEVEL TEMPERATURE
TRENDS WILL BE IMPORTANT IN RESOLVING EXACT MAGNITUDE OF
INSTABILITY/CIN. A POCKET OF AT LEAST MODERATE AFTERNOON SURFACE
BASED INSTABILITY MAY DEVELOP ACROSS SOUTHERN HALF OF THE AREA IN
THE AFTERNOON...AND GIVEN ALL ABOVE FACTORS SLIGHT CHANCE TO LOW
CHANCE TSRA POPS STILL SEEM TO BE IN ORDER. SEVERE THREAT WILL BE
LIMITED BY WEAK MID LEVEL LAPSE RATES AND MARGINAL SHEAR
PROFILES...WITH MODELS GENERALLY INDICATING BELT OF SLIGHTLY
STRONGER MID/UPPER FLOW SHIFTING SOUTHEAST OF THE AREA IN THE
AFTERNOON. THE OTHER CONCERN FOR WEDNESDAY WILL BE ON TEMPERATURES
PARTICULARLY ACROSS THE SOUTH IN ADVANCE OF THE FRONT. POOLED LOWER
70S DEW POINTS APPEAR TO BE A GOOD POSSIBILITY...AND WITH FORECASTED
HIGHS IN THE LOWER 90S...PEAK AFTERNOON HEAT INDICES COULD REACH
INTO THE MID 90S...AND INTO THE UPPER 90S FAR SOUTH IF SOME
INSOLATION CAN BE REALIZED.
COOLER AND LESS HUMID CONDITIONS FOR THURSDAY...ALTHOUGH
TEMPERATURES STILL EXPECTED ABOVE NORMAL GIVEN SHALLOW AND WEAK
NATURE OF COOL FRONT. MODELS CONTINUE TO SUGGEST UPPER RIDGE AXIS TO
RETROGRADE SLIGHTLY WESTWARD WITH RENEWED WARM ADVECTION/THETA
ADVECTION FORCING WORKING IN FROM THE WEST FOR THE FRIDAY/SATURDAY
PERIOD. MUCH TOO EARLY TO RESOLVE TIMING OF FAST MOVING SHORT WAVES
RIDING DOWN THE RIDGE...BUT 20-30 POPS MAINTAINED THROUGH THIS
PERIOD GIVEN LARGE SCALE PATTERN SUPPORT.
FORECAST CONFIDENCE QUITE LOW FOR SUNDAY AND BEYOND WITH MEDIUM
RANGE MODELS SHOWING SOME RUN TO RUN VOLATILITY AS OF LATE.
INTERESTINGLY...00Z GFS HAS MADE A SHARP TURN TOWARD THE IDEA OF
PAST FEW RUNS OF THE ECMWF IN MORE AGGRESSIVELY DIGGING LARGE SCALE
UPPER TROUGH ACROSS SOUTHEAST CANADA/NORTHEAST CONUS FOR THE LATE
SUNDAY/MONDAY PERIOD...WITH A VERY COOL AIR MASS DROPPING INTO THE
GREAT LAKES REGION. EC REMAINS IN OUTLIER IN COMPARISON TO GFS/GEFS
WITH DEPTH OF THIS TROUGH BUT GIVEN AT LEAST A TREND TO CONVERGING
SOLUTIONS HAVE STEERED FORECAST TOWARD THIS COOLER IDEA MENTIONED IN
PREVIOUS DISCUSSION. SOME CHANCE OF PRECIP WOULD LIKELY ACCOMPANY
ASSOCIATED COLD FRONT...BUT WITH LARGE RUN TO RUN DIFFERENCES WILL
KEEP DAYS 6/7 DRY FOR THIS PACKAGE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 650 AM EDT TUE AUG 27 2013
ACTIVE PATTERN OF CONVECTION TO CONTINUE THIS PERIOD AROUND
NORTHERN PERIPHERY OF PERSISTENT CENTRAL CONUS UPPER RIDGE. ONE
MCS CONTINUES TO DECAY ACROSS LOWER MICHIGAN...AND ANY
PRECIPITATION THROUGH THE MORNING SHOULD REMAIN NORTH AND EAST OF
THE TERMINALS. THE NEXT UPPER LEVEL SHORT WAVE ROUNDING THE RIDGE
HAS AIDED IN THE INITIATION OF NEW CONVECTION ACROSS NORTHERN
WISCONSIN. CONVECTION WILL LIKELY EXPAND SOUTHEAST FROM NORTHERN
WISCONSIN THROUGH THE DAY...AND INTO NORTHERN INDIANA THIS
EVENING. BEST CHANCES OF THUNDERSTORMS APPEAR TO BE JUST EAST OF
TERMINALS...BUT SCATTERED COVERAGE IS A POSSIBILITY AT BOTH
TERMINALS FROM MID EVENING INTO THE OVERNIGHT AND HAVE INCLUDED
VCTS MENTION AT THIS FORECAST DISTANCE.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
UPDATE...FISHER
SYNOPSIS...FISHER
SHORT TERM...SKIPPER
LONG TERM...MARSILI
AVIATION...MARSILI
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1250 PM CDT TUE AUG 27 2013
.SYNOPSIS...
ISSUED AT 357 AM CDT TUE AUG 27 2013
LARGE...NEARLY STATIONARY UPPER LEVEL HIGH CENTERED OVER EASTERN KS
AND MO AND DOME OF UNSEASONABLY WARM AIR ALOFT CONTINUES TO DOMINATE
THE SYNOPTIC WEATHER PICTURE. TONIGHT/S PRIMARY MCS...ROUNDING THE
TOP OF THE RIDGE WAS EVIDENT ON SATELLITE AND RADAR IMAGERY MOVING
INTO WESTERN LOWER MI...WHILE ADDITIONAL THUNDERSTORMS WERE
DEVELOPING FURTHER UPSTREAM NEAR DLH. AN ASSOCIATED SHIELD OF THIN
CI WAS COVERING MUCH OF EASTERN IA AND NORTHERN IL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED OVER EASTERN SD WITH A SURFACE
COLD FRONT/TROUGH REACHING EAST-NORTHEAST ACROSS CENTRAL MN AND
WI. SURFACE TEMPERATURES WERE IN THE LOWER TO MID 70S WITH
DEWPOINTS IN THE MID 60S TO AROUND 70 OVER THE FORECAST AREA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE AUG 27 2013
FOCUS IS ON POTENTIALLY RECORD BREAKING HEAT TODAY AS THERMAL RIDGE
ALOFT OVERHEAD WILL SUPPORT THE HOTTEST TEMPERATURES SO FAR OF
THE ON-GOING HEAT WAVE. DEEP MIXING AHEAD OF THE APPROACHING
FRONT IN THE NORTHERN PLAINS AND UPPER MS VALLEY WILL TAP INTO THE
THERMAL RIDGE OF 850 TEMPERATURES IN THE RANGE OF 22 TO 23 DEGREES
C. THIS SUPPORTS HIGHS IN THE MID TO UPPER 90S...AND CONTINUES A
TREND OF 1 TO 3 DEGREES DAY TO DAY WARMING TREND SINCE THE
WEEKEND. BASED ON VERIFICATION...WILL CONTINUE TO BUFFER MAXES
ALONG THE MORE MOIST HIGHWAY 20 CORRIDOR DOWN A DEGREE OR TWO. THE
KEY TO HOW HIGH THE HEAT INDEX GETS WILL BE HOW SURFACE DEWPOINTS
RESPOND TO STRONGER WINDS AND DEEP MIXING TODAY. FORECAST MODELS
ARE IN A COUPLE DIFFERENT CAMPS...WITH THE RAP SUGGESTING DRYING
OUT TO THE UPPER 50S TO LOWER 60 BY AFTERNOON...WHILE THE BULK OF
OTHER SHORT TERM MODELS ARE MUCH MORE MOIST WITH SOME SUGGESTING
POOLING OF LOWER TO MID 70S ACROSS THE NORTH. BASED ON
VERIFICATION FROM YESTERDAY HERE AND UPSTREAM IN THE
PLAINS...DEWPOINTS WILL MORE LIKELY RISE A FEW DEGREES EARLY THIS
MORNING...THEN SETTLE IN THE INTO THE MID TO UPPER 60S IN THE
AFTERNOON AS SW WINDS INCREASE TO 10 TO 15 MPH. UNLIKE
YESTERDAY...THE CLOUD SHIELD FROM THE NOCTURNAL CONVECTION SHOULD
BE OUT OF THE REGION BY MID MORNING...YIELDING NEAR FULL SUNSHINE
FOR THE AFTERNOON. HOWEVER...WILL NEED TO WATCH THE NW WI COMPLEX TRENDS
CLOSELY...AS THIS COULD POSSIBLY LEAD TO ANOTHER CI SHIELD IF IT
REMAINS STRONG...FOR LATER THIS MORNING.
HEAT INDEX READINGS THUS ARE EXPECTED TO REACH 100 TO 104 BY EARLY
AFTERNOON OVER MUCH OF THE FORECAST AREA...WITH A GENERAL GRADIENT
FROM LOWER VALUES EAST TO HIGHER WEST AND NW. THE ON-GOING HEAT
ADVISORY WILL THUS REMAIN INTACT...AND IS EXTENDED INTO WED AS
COVERED IN THE LONG TERM AFD SEGMENT.
RECORD TEMPERATURES...AS MENTIONED IN THE CLIMATE SEGMENT
BELOW...APPEAR TO BE MOST AT RISK AT CID AND BRL.
VERY WARM AND HUMID CONDITIONS WILL THEN PREVAIL TONIGHT AS THE
SURFACE COOL FRONT SETTLES SOUTH TO ROUGHLY ALONG THE I-80 CORRIDOR
BY DAWN. ASSOCIATED MOISTURE POOLING AND LIGHT WINDS WILL MAKE FOR
UNCOMFORTABLE CONDITIONS. TEMPERATURES WILL BE IN THE UPPER 70S
TO LOWER 80 FOR MUCH OF THE NIGHT...COOLING TO LOWS AROUND SUNRISE
IN THE LOWER TO MID 70S. THERE IS A LOW POTENTIAL FOR CONVECTION
ALONG THIS BOUNDARY...BUT ANYTHING THAT DEVELOPS WILL LIKELY STAY
WELL EAST OF THE FORECAST AREA...WHERE THE CAP WILL BE WEAKER AND
HAVE KEPT MENTIONABLE POPS OUT OF THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE AUG 27 2013
FORECAST FOCUS ON HOT AND HUMID WEATHER INTO THE WEEKEND BUT THEN
MUCH COOLER BY LABOR DAY.
WEDNESDAY THROUGH SATURDAY...HAVE EXTENDED THE HEAT ADVISORY FOR
MOST OF THE CWA INTO EARLY WEDNESDAY EVENING. A WEAK BACK DOOR COLD
FRONT WILL PUSH ACROSS THE CWA BUT THE MAIN IMPACT WILL BE TO POOL
HIGHER DEWPOINTS ALONG THE BOUNDARY. MOST OF THE CWA WILL HAVE
AFTERNOON TEMPERATURES IN THE LOWER TO MID 90S WITH DEWPOINTS IN THE
LOWER 70S CREATING HEAT INDEX VALUES OF 100 TO 104. THE EXCEPTION
WILL BE OUR FAR NORTH AND NORTHEAST COUNTIES WHERE TEMPERATURES AND
DEWPOINTS WILL BE SOMEWHAT LOWER BEHIND THE FRONT.
THERE WILL BE A BRIEF BREAK ON THURSDAY WITH NORTHEAST WINDS BEHIND
THE FRONT KEEPING HEAT INDEX VALUES BELOW ADVISORY CRITERIA. HOWEVER
BY FRIDAY THE WEAK FRONT RETURNS AS A WARM FRONT AND LIFTS TO OUR
NORTHEAST BRINGING DEWPOINTS BACK INTO THE LOWER 70S AND HIGHS IN
THE LOWER TO MID 90S. HEAT INDEX VALUES WILL ONCE AGAIN PUSH INTO
THE 100 TO 104 RANGE AND THIS COULD POSSIBLY CONTINUE INTO SATURDAY.
THERE ARE SMALL CHANCES OF THUNDERSTORMS FOR BOTH THURSDAY NIGHT AND
FRIDAY NIGHT...BUT CONFIDENCE IS LOW. THIS IS BASED ON THE
OPERATIONAL MODELS INDICATING RIDGE RIDERS MOVING ACROSS THE UPPER
MIDWEST BUT THE BULK OF THE STORMS SHOULD REMAIN ACROSS MN AND WI.
SUNDAY AND LABOR DAY...THE ECMWF FOR 3 STRAIGHT RUNS HAS SHOWN THE
PLUNGE OF MUCH COOLER TEMPERATURES INTO THE MIDWEST AND GREAT LAKES.
IN FACT...THIS MODEL BRINGS THE 2C 850 MB TEMPERATURE LINE TO NEAR
CHICAGO ON LABOR DAY. CONFIDENCE GROWING THAT THIS IS FOR REAL AS
THE GFS/GEM ARE ALSO ON BOARD WITH THIS DEEPENING TROUGH IN THE
EAST...BUT NOT NEARLY AS COLD AS THE ECMWF. THE STRONG COLD FRONT
SHOULD PUSH INTO THE DVN CWA SOMETIME ON SUNDAY AND THE OPERATIONAL
MODELS SUGGEST THE POTENTIAL FOR AT LEAST ISOLATED TO SCATTERED
THUNDERSTORMS ACCOMPANYING THE FRONT...SUNDAY AFTERNOON OR EVENING.
FOR NOW THE GRIDS ARE DRY BUT LATER SHIFTS WILL NEED TO RE-EVALUATE
THE CHANCES OF THUNDERSTORMS. SURROUNDING OFFICES CONSENSUS WAS TO
LOWER TEMPERATURES ON SUNDAY AND LABOR DAY WITH THE FRONT STRONGER
AND ARRIVING SOONER THAN EARLIER DEPICTED.
AT THIS POINT IN THE GAME LABOR DAY LOOKS VERY PLEASANT WITH
COMFORTABLE HUMIDITY AND MAXIMUM TEMPERATURES IN THE 80S...ACTUALLY
AROUND 80 IN OUR FAR NORTHEAST CWA.
THIS COOLER AIR IS SHORT LIVED AS IT APPEARS THE HEAT AND HUMIDITY
QUICKLY RETURN BY THE MIDDLE OF NEXT WEEK.
HAASE
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1246 PM CDT TUE AUG 27 2013
VFR CONDITIONS TO CONTINUE WITH FAIR SKIES...VERY WARM AND HUMID
CONDITIONS. SOUTHWEST WINDS OF 10 TO 20 MPH WILL BECOME LIGHT
WESTERLY TONIGHT. A WEAK BACK DOOR COOL FRONT WILL PASS ACROSS THE
TERMINALS BETWEEN 28/12-18Z...SHIFTING THE WINDS TO THE NORTHEAST
AT 5 TO 10 MPH. SKIES WILL REMAIN FAIR AFTER THE FRONT PASSES.
&&
.CLIMATE...
ISSUED AT 357 AM CDT TUE AUG 27 2013
RECORD HIGHS FOR AUGUST 27...
MOLINE.........97 IN 1976
CEDAR RAPIDS...97 IN 1955
DUBUQUE........94 IN 1895
BURLINGTON.....97 IN 1955
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR BUCHANAN-DELAWARE-
DUBUQUE-JACKSON.
HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR BENTON-CEDAR-CLINTON-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR CARROLL-JO
DAVIESS-STEPHENSON.
HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR BUREAU-HANCOCK-
HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-
WARREN-WHITESIDE.
MO...HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR CLARK-SCOTLAND.
&&
$$
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...NICHOLS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
622 AM CDT TUE AUG 27 2013
.SYNOPSIS...
ISSUED AT 357 AM CDT TUE AUG 27 2013
LARGE...NEARLY STATIONARY UPPER LEVEL HIGH CENTERED OVER EASTERN KS
AND MO AND DOME OF UNSEASONABLY WARM AIR ALOFT CONTINUES TO DOMINATE
THE SYNOPTIC WEATHER PICTURE. TONIGHT/S PRIMARY MCS...ROUNDING THE
TOP OF THE RIDGE WAS EVIDENT ON SATELLITE AND RADAR IMAGERY MOVING
INTO WESTERN LOWER MI...WHILE ADDITIONAL THUNDERSTORMS WERE
DEVELOPING FURTHER UPSTREAM NEAR DLH. AN ASSOCIATED SHIELD OF THIN
CI WAS COVERING MUCH OF EASTERN IA AND NORTHERN IL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED OVER EASTERN SD WITH A SURFACE
COLD FRONT/TROUGH REACHING EAST-NORTHEAST ACROSS CENTRAL MN AND
WI. SURFACE TEMPERATURES WERE IN THE LOWER TO MID 70S WITH
DEWPOINTS IN THE MID 60S TO AROUND 70 OVER THE FORECAST AREA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE AUG 27 2013
FOCUS IS ON POTENTIALLY RECORD BREAKING HEAT TODAY AS THERMAL RIDGE
ALOFT OVERHEAD WILL SUPPORT THE HOTTEST TEMPERATURES SO FAR OF
THE ON-GOING HEAT WAVE. DEEP MIXING AHEAD OF THE APPROACHING
FRONT IN THE NORTHERN PLAINS AND UPPER MS VALLEY WILL TAP INTO THE
THERMAL RIDGE OF 850 TEMPERATURES IN THE RANGE OF 22 TO 23 DEGREES
C. THIS SUPPORTS HIGHS IN THE MID TO UPPER 90S...AND CONTINUES A
TREND OF 1 TO 3 DEGREES DAY TO DAY WARMING TREND SINCE THE
WEEKEND. BASED ON VERIFICATION...WILL CONTINUE TO BUFFER MAXES
ALONG THE MORE MOIST HIGHWAY 20 CORRIDOR DOWN A DEGREE OR TWO. THE
KEY TO HOW HIGH THE HEAT INDEX GETS WILL BE HOW SURFACE DEWPOINTS
RESPOND TO STRONGER WINDS AND DEEP MIXING TODAY. FORECAST MODELS
ARE IN A COUPLE DIFFERENT CAMPS...WITH THE RAP SUGGESTING DRYING
OUT TO THE UPPER 50S TO LOWER 60 BY AFTERNOON...WHILE THE BULK OF
OTHER SHORT TERM MODELS ARE MUCH MORE MOIST WITH SOME SUGGESTING
POOLING OF LOWER TO MID 70S ACROSS THE NORTH. BASED ON
VERIFICATION FROM YESTERDAY HERE AND UPSTREAM IN THE
PLAINS...DEWPOINTS WILL MORE LIKELY RISE A FEW DEGREES EARLY THIS
MORNING...THEN SETTLE IN THE INTO THE MID TO UPPER 60S IN THE
AFTERNOON AS SW WINDS INCREASE TO 10 TO 15 MPH. UNLIKE
YESTERDAY...THE CLOUD SHIELD FROM THE NOCTURNAL CONVECTION SHOULD
BE OUT OF THE REGION BY MID MORNING...YIELDING NEAR FULL SUNSHINE
FOR THE AFTERNOON. HOWEVER...WILL NEED TO WATCH THE NW WI COMPLEX TRENDS
CLOSELY...AS THIS COULD POSSIBLY LEAD TO ANOTHER CI SHIELD IF IT
REMAINS STRONG...FOR LATER THIS MORNING.
HEAT INDEX READINGS THUS ARE EXPECTED TO REACH 100 TO 104 BY EARLY
AFTERNOON OVER MUCH OF THE FORECAST AREA...WITH A GENERAL GRADIENT
FROM LOWER VALUES EAST TO HIGHER WEST AND NW. THE ON-GOING HEAT
ADVISORY WILL THUS REMAIN INTACT...AND IS EXTENDED INTO WED AS
COVERED IN THE LONG TERM AFD SEGMENT.
RECORD TEMPERATURES...AS MENTIONED IN THE CLIMATE SEGMENT
BELOW...APPEAR TO BE MOST AT RISK AT CID AND BRL.
VERY WARM AND HUMID CONDITIONS WILL THEN PREVAIL TONIGHT AS THE
SURFACE COOL FRONT SETTLES SOUTH TO ROUGHLY ALONG THE I-80 CORRIDOR
BY DAWN. ASSOCIATED MOISTURE POOLING AND LIGHT WINDS WILL MAKE FOR
UNCOMFORTABLE CONDITIONS. TEMPERATURES WILL BE IN THE UPPER 70S
TO LOWER 80 FOR MUCH OF THE NIGHT...COOLING TO LOWS AROUND SUNRISE
IN THE LOWER TO MID 70S. THERE IS A LOW POTENTIAL FOR CONVECTION
ALONG THIS BOUNDARY...BUT ANYTHING THAT DEVELOPS WILL LIKELY STAY
WELL EAST OF THE FORECAST AREA...WHERE THE CAP WILL BE WEAKER AND
HAVE KEPT MENTIONABLE POPS OUT OF THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE AUG 27 2013
FORECAST FOCUS ON HOT AND HUMID WEATHER INTO THE WEEKEND BUT THEN
MUCH COOLER BY LABOR DAY.
WEDNESDAY THROUGH SATURDAY...HAVE EXTENDED THE HEAT ADVISORY FOR
MOST OF THE CWA INTO EARLY WEDNESDAY EVENING. A WEAK BACK DOOR COLD
FRONT WILL PUSH ACROSS THE CWA BUT THE MAIN IMPACT WILL BE TO POOL
HIGHER DEWPOINTS ALONG THE BOUNDARY. MOST OF THE CWA WILL HAVE
AFTERNOON TEMPERATURES IN THE LOWER TO MID 90S WITH DEWPOINTS IN THE
LOWER 70S CREATING HEAT INDEX VALUES OF 100 TO 104. THE EXCEPTION
WILL BE OUR FAR NORTH AND NORTHEAST COUNTIES WHERE TEMPERATURES AND
DEWPOINTS WILL BE SOMEWHAT LOWER BEHIND THE FRONT.
THERE WILL BE A BRIEF BREAK ON THURSDAY WITH NORTHEAST WINDS BEHIND
THE FRONT KEEPING HEAT INDEX VALUES BELOW ADVISORY CRITERIA. HOWEVER
BY FRIDAY THE WEAK FRONT RETURNS AS A WARM FRONT AND LIFTS TO OUR
NORTHEAST BRINGING DEWPOINTS BACK INTO THE LOWER 70S AND HIGHS IN
THE LOWER TO MID 90S. HEAT INDEX VALUES WILL ONCE AGAIN PUSH INTO
THE 100 TO 104 RANGE AND THIS COULD POSSIBLY CONTINUE INTO SATURDAY.
THERE ARE SMALL CHANCES OF THUNDERSTORMS FOR BOTH THURSDAY NIGHT AND
FRIDAY NIGHT...BUT CONFIDENCE IS LOW. THIS IS BASED ON THE
OPERATIONAL MODELS INDICATING RIDGE RIDERS MOVING ACROSS THE UPPER
MIDWEST BUT THE BULK OF THE STORMS SHOULD REMAIN ACROSS MN AND WI.
SUNDAY AND LABOR DAY...THE ECMWF FOR 3 STRAIGHT RUNS HAS SHOWN THE
PLUNGE OF MUCH COOLER TEMPERATURES INTO THE MIDWEST AND GREAT LAKES.
IN FACT...THIS MODEL BRINGS THE 2C 850 MB TEMPERATURE LINE TO NEAR
CHICAGO ON LABOR DAY. CONFIDENCE GROWING THAT THIS IS FOR REAL AS
THE GFS/GEM ARE ALSO ON BOARD WITH THIS DEEPENING TROUGH IN THE
EAST...BUT NOT NEARLY AS COLD AS THE ECMWF. THE STRONG COLD FRONT
SHOULD PUSH INTO THE DVN CWA SOMETIME ON SUNDAY AND THE OPERATIONAL
MODELS SUGGEST THE POTENTIAL FOR AT LEAST ISOLATED TO SCATTERED
THUNDERSTORMS ACCOMPANYING THE FRONT...SUNDAY AFTERNOON OR EVENING.
FOR NOW THE GRIDS ARE DRY BUT LATER SHIFTS WILL NEED TO RE-EVALUATE
THE CHANCES OF THUNDERSTORMS. SURROUNDING OFFICES CONSENSUS WAS TO
LOWER TEMPERATURES ON SUNDAY AND LABOR DAY WITH THE FRONT STRONGER
AND ARRIVING SOONER THAN EARLIER DEPICTED.
AT THIS POINT IN THE GAME LABOR DAY LOOKS VERY PLEASANT WITH
COMFORTABLE HUMIDITY AND MAXIMUM TEMPERATURES IN THE 80S...ACTUALLY
AROUND 80 IN OUR FAR NORTHEAST CWA.
THIS COOLER AIR IS SHORT LIVED AS IT APPEARS THE HEAT AND HUMIDITY
QUICKLY RETURN BY THE MIDDLE OF NEXT WEEK.
HAASE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 622 AM CDT TUE AUG 27 2013
CONDITIONS WILL REMAIN VFR TODAY WITH SOUTHWEST WINDS BECOMING
GUSTY DURING THE AFTERNOON FROM 13 TO 20 KTS. A WEAK FRONT WILL
DROP SOUTH INTO THE REGION TONIGHT. MOISTURE POOLING ALONG THIS
BOUNDARY WILL LIKELY LEAD TO SOME MORNING FOG...ESPECIALLY AT CID
AND DBQ. FOR NOW...HAVE GONE WITH PREVAILING MVFR VISIBILITIES
AROUND 8Z TO 9Z TUESDAY MORNING. THERE IS A POTENTIAL FOR PERIODS
LOWER VISIBILITIES INTO IFR RANGE...WHICH MAY BE INCLUDED IN
LATER FORECASTS IF CONFIDENCE INCREASES.
&&
.CLIMATE...
ISSUED AT 357 AM CDT TUE AUG 27 2013
RECORD HIGHS FOR AUGUST 27...
MOLINE.........97 IN 1976
CEDAR RAPIDS...97 IN 1955
DUBUQUE........94 IN 1895
BURLINGTON.....97 IN 1955
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR BUCHANAN-DELAWARE-
DUBUQUE-JACKSON.
HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR BENTON-CEDAR-CLINTON-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR HANCOCK-HENDERSON-
MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
HEAT ADVISORY FROM NOON TODAY TO 10 PM CDT THIS EVENING FOR
CARROLL-JO DAVIESS-STEPHENSON.
HEAT ADVISORY FROM NOON TODAY TO 7 PM CDT WEDNESDAY FOR BUREAU-
HENRY IL-PUTNAM-WHITESIDE.
MO...HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR CLARK-SCOTLAND.
&&
$$
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...SHEETS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
357 AM CDT TUE AUG 27 2013
.SYNOPSIS...
ISSUED AT 349 AM CDT TUE AUG 27 2013
LARGE...NEARLY STATIONARY UPPER LEVEL HIGH CENTERED OVER EASTERN KS
AND MO AND DOME OF UNSEASONABLY WARM AIR ALOFT CONTINUES TO DOMINATE
THE SYNOPTIC WEATHER PICTURE. TONIGHT/S PRIMARY MCS...ROUNDING THE
TOP OF THE RIDGE WAS EVIDENT ON SATELLITE AND RADAR IMAGERY MOVING
INTO WESTERN LOWER MI...WHILE ADDITIONAL THUNDERSTORMS WERE
DEVELOPING FURTHER UPSTREAM NEAR DLH. AN ASSOCIATED SHIELD OF THIN
CI WAS COVERING MUCH OF EASTERN IA AND NORTHERN IL. AT THE
SURFACE...LOW PRESSURE WAS CENTERED OVER EASTERN SD WITH A SURFACE
COLD FRONT/TROUGH REACHING EAST-NORTHEAST ACROSS CENTRAL MN AND
WI. SURFACE TEMPERATURES WERE IN THE LOWER TO MID 70S WITH
DEWPOINTS IN THE MID 60S TO AROUND 70 OVER THE FORECAST AREA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT TUE AUG 27 2013
FOCUS IS ON POTENTIALLY RECORD BREAKING HEAT TODAY AS THERMAL RIDGE
ALOFT OVERHEAD WILL SUPPORT THE HOTTEST TEMPERATURES SO FAR OF
THE ON-GOING HEAT WAVE. DEEP MIXING AHEAD OF THE APPROACHING
FRONT IN THE NORTHERN PLAINS AND UPPER MS VALLEY WILL TAP INTO THE
THERMAL RIDGE OF 850 TEMPERATURES IN THE RANGE OF 22 TO 23 DEGREES
C. THIS SUPPORTS HIGHS IN THE MID TO UPPER 90S...AND CONTINUES A
TREND OF 1 TO 3 DEGREES DAY TO DAY WARMING TREND SINCE THE
WEEKEND. BASED ON VERIFICATION...WILL CONTINUE TO BUFFER MAXES
ALONG THE MORE MOIST HIGHWAY 20 CORRIDOR DOWN A DEGREE OR TWO. THE
KEY TO HOW HIGH THE HEAT INDEX GETS WILL BE HOW SURFACE DEWPOINTS
RESPOND TO STRONGER WINDS AND DEEP MIXING TODAY. FORECAST MODELS
ARE IN A COUPLE DIFFERENT CAMPS...WITH THE RAP SUGGESTING DRYING
OUT TO THE UPPER 50S TO LOWER 60 BY AFTERNOON...WHILE THE BULK OF
OTHER SHORT TERM MODELS ARE MUCH MORE MOIST WITH SOME SUGGESTING
POOLING OF LOWER TO MID 70S ACROSS THE NORTH. BASED ON
VERIFICATION FROM YESTERDAY HERE AND UPSTREAM IN THE
PLAINS...DEWPOINTS WILL MORE LIKELY RISE A FEW DEGREES EARLY THIS
MORNING...THEN SETTLE IN THE INTO THE MID TO UPPER 60S IN THE
AFTERNOON AS SW WINDS INCREASE TO 10 TO 15 MPH. UNLIKE
YESTERDAY...THE CLOUD SHIELD FROM THE NOCTURNAL CONVECTION SHOULD
BE OUT OF THE REGION BY MID MORNING...YIELDING NEAR FULL SUNSHINE
FOR THE AFTERNOON. HOWEVER...WILL NEED TO WATCH THE NW WI COMPLEX TRENDS
CLOSELY...AS THIS COULD POSSIBLY LEAD TO ANOTHER CI SHIELD IF IT
REMAINS STRONG...FOR LATER THIS MORNING.
HEAT INDEX READINGS THUS ARE EXPECTED TO REACH 100 TO 104 BY EARLY
AFTERNOON OVER MUCH OF THE FORECAST AREA...WITH A GENERAL GRADIENT
FROM LOWER VALUES EAST TO HIGHER WEST AND NW. THE ON-GOING HEAT
ADVISORY WILL THUS REMAIN INTACT...AND IS EXTENDED INTO WED AS
COVERED IN THE LONG TERM AFD SEGMENT.
RECORD TEMPERATURES...AS MENTIONED IN THE CLIMATE SEGMENT
BELOW...APPEAR TO BE MOST AT RISK AT CID AND BRL.
VERY WARM AND HUMID CONDITIONS WILL THEN PREVAIL TONIGHT AS THE
SURFACE COOL FRONT SETTLES SOUTH TO ROUGHLY ALONG THE I-80 CORRIDOR
BY DAWN. ASSOCIATED MOISTURE POOLING AND LIGHT WINDS WILL MAKE FOR
UNCOMFORTABLE CONDITIONS. TEMPERATURES WILL BE IN THE UPPER 70S
TO LOWER 80 FOR MUCH OF THE NIGHT...COOLING TO LOWS AROUND SUNRISE
IN THE LOWER TO MID 70S. THERE IS A LOW POTENTIAL FOR CONVECTION
ALONG THIS BOUNDARY...BUT ANYTHING THAT DEVELOPS WILL LIKELY STAY
WELL EAST OF THE FORECAST AREA...WHERE THE CAP WILL BE WEAKER AND
HAVE KEPT MENTIONABLE POPS OUT OF THE FORECAST.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 349 AM CDT TUE AUG 27 2013
FORECAST FOCUS ON HOT AND HUMID WEATHER INTO THE WEEKEND BUT THEN
MUCH COOLER BY LABOR DAY.
WEDNESDAY THROUGH SATURDAY...HAVE EXTENDED THE HEAT ADVISORY FOR
MOST OF THE CWA INTO EARLY WEDNESDAY EVENING. A WEAK BACK DOOR COLD
FRONT WILL PUSH ACROSS THE CWA BUT THE MAIN IMPACT WILL BE TO POOL
HIGHER DEWPOINTS ALONG THE BOUNDARY. MOST OF THE CWA WILL HAVE
AFTERNOON TEMPERATURES IN THE LOWER TO MID 90S WITH DEWPOINTS IN THE
LOWER 70S CREATING HEAT INDEX VALUES OF 100 TO 104. THE EXCEPTION
WILL BE OUR FAR NORTH AND NORTHEAST COUNTIES WHERE TEMPERATURES AND
DEWPOINTS WILL BE SOMEWHAT LOWER BEHIND THE FRONT.
THERE WILL BE A BRIEF BREAK ON THURSDAY WITH NORTHEAST WINDS BEHIND
THE FRONT KEEPING HEAT INDEX VALUES BELOW ADVISORY CRITERIA. HOWEVER
BY FRIDAY THE WEAK FRONT RETURNS AS A WARM FRONT AND LIFTS TO OUR
NORTHEAST BRINGING DEWPOINTS BACK INTO THE LOWER 70S AND HIGHS IN
THE LOWER TO MID 90S. HEAT INDEX VALUES WILL ONCE AGAIN PUSH INTO
THE 100 TO 104 RANGE AND THIS COULD POSSIBLY CONTINUE INTO SATURDAY.
THERE ARE SMALL CHANCES OF THUNDERSTORMS FOR BOTH THURSDAY NIGHT AND
FRIDAY NIGHT...BUT CONFIDENCE IS LOW. THIS IS BASED ON THE
OPERATIONAL MODELS INDICATING RIDGE RIDERS MOVING ACROSS THE UPPER
MIDWEST BUT THE BULK OF THE STORMS SHOULD REMAIN ACROSS MN AND WI.
SUNDAY AND LABOR DAY...THE ECMWF FOR 3 STRAIGHT RUNS HAS SHOWN THE
PLUNGE OF MUCH COOLER TEMPERATURES INTO THE MIDWEST AND GREAT LAKES.
IN FACT...THIS MODEL BRINGS THE 2C 850 MB TEMPERATURE LINE TO NEAR
CHICAGO ON LABOR DAY. CONFIDENCE GROWING THAT THIS IS FOR REAL AS
THE GFS/GEM ARE ALSO ON BOARD WITH THIS DEEPENING TROUGH IN THE
EAST...BUT NOT NEARLY AS COLD AS THE ECMWF. THE STRONG COLD FRONT
SHOULD PUSH INTO THE DVN CWA SOMETIME ON SUNDAY AND THE OPERATIONAL
MODELS SUGGEST THE POTENTIAL FOR AT LEAST ISOLATED TO SCATTERED
THUNDERSTORMS ACCOMPANYING THE FRONT...SUNDAY AFTERNOON OR EVENING.
FOR NOW THE GRIDS ARE DRY BUT LATER SHIFTS WILL NEED TO RE-EVALUATE
THE CHANCES OF THUNDERSTORMS. SURROUNDING OFFICES CONSENSUS WAS TO
LOWER TEMPERATURES ON SUNDAY AND LABOR DAY WITH THE FRONT STRONGER
AND ARRIVING SOONER THAN EARLIER DEPICTED.
AT THIS POINT IN THE GAME LABOR DAY LOOKS VERY PLEASANT WITH
COMFORTABLE HUMIDITY AND MAXIMUM TEMPERATURES IN THE 80S...ACTUALLY
AROUND 80 IN OUR FAR NORTHEAST CWA.
THIS COOLER AIR IS SHORT LIVED AS IT APPEARS THE HEAT AND HUMIDITY
QUICKLY RETURN BY THE MIDDLE OF NEXT WEEK.
HAASE
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1132 PM CDT MON AUG 26 2013
VFR CONDITIONS AND SOUTH TO SOUTHWESTERLY WINDS WILL PERSIST
THROUGH TUESDAY EVENING. THERE IS STILL A LOW THREAT OF 3-5SM
VSBYS IF FOG AROUND SUNRISE ESPECIALLY WEST OF THE MISSISSIPPI
RIVER WHERE THE HIGH CLOUDS WILL BE THIN. A WEAK COLD FRONT WILL
SAG SOUTH INTO NORTHEAST IOWA AND SOUTHERN WISCONSIN BY LATE
TUESDAY EVENING.
&&
.CLIMATE...
ISSUED AT 349 AM CDT TUE AUG 27 2013
RECORD HIGHS FOR AUGUST 27...
MOLINE.........97 IN 1976
CEDAR RAPIDS...97 IN 1955
DUBUQUE........94 IN 1895
BURLINGTON.....97 IN 1955
RECORD HIGHS FOR AUGUST 28...
MOLINE.........96 IN 1953
CEDAR RAPIDS...96 IN 1955
DUBUQUE........97 IN 1984
BURLINGTON.....96 IN 1945
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR BUCHANAN-DELAWARE-
DUBUQUE-JACKSON.
HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR BENTON-CEDAR-CLINTON-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR HANCOCK-HENDERSON-
MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
HEAT ADVISORY FROM NOON TODAY TO 10 PM CDT THIS EVENING FOR
CARROLL-JO DAVIESS-STEPHENSON.
HEAT ADVISORY FROM NOON TODAY TO 7 PM CDT WEDNESDAY FOR BUREAU-
HENRY IL-PUTNAM-WHITESIDE.
MO...HEAT ADVISORY UNTIL 7 PM CDT WEDNESDAY FOR CLARK-SCOTLAND.
&&
$$
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...DLF
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1055 AM MDT TUE AUG 27 2013
.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 222 AM MDT TUE AUG 27 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW LARGE SCALE RIDGE STILL
IN PLACE ACROSS THE CENTRAL CONUS. THERE HAS BEEN A GENERAL
WEAKENING OF THE RIDGE CENTER...WITH CURRENT MAX HEIGHT AROUND
595/596DM. A SHORTWAVE TROUGH OVER EASTERN TEXAS SHOWS GOOD
REFLECTION IN BOTH WV AND HEIGHT FIELD AND COULD BE A MINOR FACTOR
IN TEMPS ON WED.
WITH RIDGE WELL ENTRENCHED OVER OUR CWA...THERE WILL BE VERY LITTLE
CHANGE IN THE HOT/DRY CONDITIONS. MODELS SHOW THE SHORTWAVE TROUGH
OVER EASTERN TEXAS ROUNDING SOUTH AND THEN WESTERN EDGE OF THE RIDGE
CENTER THROUGH WED NIGHT. AS HAS BEEN THE CASE THE LAST FEW
DAYS...THERE SHOULD BE GOOD FORCING AND AT LEAST SOME ELEVATED
INSTABILITY WITH THIS FEATURE. MODEL SOUNDINGS STILL SHOW DEEP DRY
AIR MASS IN PLACE...SO OTHER THAN A BRIEF INCREASE IN CLOUDS AND
SLIGHTLY COOLER TEMPS ALOFT I AM NOT ANTICIPATING PRECIP WITH THIS
FEATURE OVER OUR CWA. GENERAL TREND WILL BE A WEAKENING OF THE LEE
TROUGH WITH GRADIENT SHIFTING EASTWARD. THIS SHOULD SUPPORT LESS
WINDY CONDITIONS THROUGH THE REST OF THE FORECAST PERIOD...THOUGH A
FEW GUSTS IN THE 20-30MPH CANT BE RULED OUT THIS AFTERNOON WITH PEAK
MIXING.
REGARDING TEMPS THROUGH THURSDAY...IT LOOKS LIKE A CONTINUATION OF
THE LAST FEW DAYS WITH HIGHS GENERALLY IN THE UPPER 90S/LOW 100S. THE
ONE EXCEPTION WILL BE WED WHEN HIGHS MAY BE ABOUT 5-7F
COOLER...WHICH STILL PUTS HIGHS ACROSS THE CWA IN THE MID-UPPER 90S
FOR MANY LOCATIONS.
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 222 AM MDT TUE AUG 27 2013
MEDIUM RANGE MODEL CONSENSUS IS FOR GRADUAL SLIGHT WEAKENING OF THE
UPPER RIDGE EARLY IN EXTENDED PERIOD. A RELATIVELY SIGNIFICANT
SHORTWAVE TROUGH WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES
REGION OVER THE WEEKEND ALONG THE NORTHERN EDGE OF THE RIDGE. AN
ASSOCIATED COLD FRONT WILL MOVE SOUTH/SOUTHWESTWARD TOWARD THE AREA.
THE NEW 00Z ECMWF IS STRONGER WITH THIS SHORTWAVE AND PROGRESSES THE
COLD FRONT FURTHER SOUTHWEST INTO OUR AREA LATE SUNDAY INTO MONDAY.
THE GFS IS LESS AGGRESSIVE WITH SOUTH/SOUTHWEST PROGRESSION OF THE
COLD FRONT BUT DOES SHOW AN INCREASE IN DEEP MOISTURE ACROSS THE
AREA SUNDAY AND MONDAY WITH PWAT VALUES SLIGHTLY EXCEEDING
CLIMATOLOGY. THIS IS ENOUGH TO JUSTIFY KEEPING AT LEAST A VERY LOW
POP IN THE NORTHERN PORTION OF THE FORECAST AREA SUNDAY AND MONDAY.
BY LATE MONDAY A MORE HIGHLY AMPLIFIED PATTERN EVOLVES WITH UPPER
RIDGE STRENGTHENING ONCE AGAIN OVER THE PLAINS BETWEEN PACIFIC
NORTHWEST TROUGH AND DEEPENING TROUGH OVER THE EASTERN CONUS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1052 AM MDT TUE AUG 27 2013
VFR CONDITIONS WILL CONTINUE FOR KGLD AND KMCK FOR THE NEXT 24
HOURS AS A RIDGE CONTINUES OVER THE PLAINS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BRB
AVIATION...FS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
528 AM MDT TUE AUG 27 2013
.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 222 AM MDT TUE AUG 27 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW LARGE SCALE RIDGE STILL
IN PLACE ACROSS THE CENTRAL CONUS. THERE HAS BEEN A GENERAL
WEAKENING OF THE RIDGE CENTER...WITH CURRENT MAX HEIGHT AROUND
595/596DM. A SHORTWAVE TROUGH OVER EASTERN TEXAS SHOWS GOOD
REFLECTION IN BOTH WV AND HEIGHT FIELD AND COULD BE A MINOR FACTOR
IN TEMPS ON WED.
WITH RIDGE WELL ENTRENCHED OVER OUR CWA...THERE WILL BE VERY LITTLE
CHANGE IN THE HOT/DRY CONDITIONS. MODELS SHOW THE SHORTWAVE TROUGH
OVER EASTERN TEXAS ROUNDING SOUTH AND THEN WESTERN EDGE OF THE RIDGE
CENTER THROUGH WED NIGHT. AS HAS BEEN THE CASE THE LAST FEW
DAYS...THERE SHOULD BE GOOD FORCING AND AT LEAST SOME ELEVATED
INSTABILITY WITH THIS FEATURE. MODEL SOUNDINGS STILL SHOW DEEP DRY
AIR MASS IN PLACE...SO OTHER THAN A BRIEF INCREASE IN CLOUDS AND
SLIGHTLY COOLER TEMPS ALOFT I AM NOT ANTICIPATING PRECIP WITH THIS
FEATURE OVER OUR CWA. GENERAL TREND WILL BE A WEAKENING OF THE LEE
TROUGH WITH GRADIENT SHIFTING EASTWARD. THIS SHOULD SUPPORT LESS
WINDY CONDITIONS THROUGH THE REST OF THE FORECAST PERIOD...THOUGH A
FEW GUSTS IN THE 20-30MPH CANT BE RULED OUT THIS AFTERNOON WITH PEAK
MIXING.
REGARDING TEMPS THROUGH THURSDAY...IT LOOKS LIKE A CONTINUATION OF
THE LAST FEW DAYS WITH HIGHS GENERALLY IN THE UPPER 90S/LOW 100S. THE
ONE EXCEPTION WILL BE WED WHEN HIGHS MAY BE ABOUT 5-7F
COOLER...WHICH STILL PUTS HIGHS ACROSS THE CWA IN THE MID-UPPER 90S
FOR MANY LOCATIONS.
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 222 AM MDT TUE AUG 27 2013
MEDIUM RANGE MODEL CONSENSUS IS FOR GRADUAL SLIGHT WEAKENING OF THE
UPPER RIDGE EARLY IN EXTENDED PERIOD. A RELATIVELY SIGNIFICANT
SHORTWAVE TROUGH WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES
REGION OVER THE WEEKEND ALONG THE NORTHERN EDGE OF THE RIDGE. AN
ASSOCIATED COLD FRONT WILL MOVE SOUTH/SOUTHWESTWARD TOWARD THE AREA.
THE NEW 00Z ECMWF IS STRONGER WITH THIS SHORTWAVE AND PROGRESSES THE
COLD FRONT FURTHER SOUTHWEST INTO OUR AREA LATE SUNDAY INTO MONDAY.
THE GFS IS LESS AGGRESSIVE WITH SOUTH/SOUTHWEST PROGRESSION OF THE
COLD FRONT BUT DOES SHOW AN INCREASE IN DEEP MOISTURE ACROSS THE
AREA SUNDAY AND MONDAY WITH PWAT VALUES SLIGHTLY EXCEEDING
CLIMATOLOGY. THIS IS ENOUGH TO JUSTIFY KEEPING AT LEAST A VERY LOW
POP IN THE NORTHERN PORTION OF THE FORECAST AREA SUNDAY AND MONDAY.
BY LATE MONDAY A MORE HIGHLY AMPLIFIED PATTERN EVOLVES WITH UPPER
RIDGE STRENGTHENING ONCE AGAIN OVER THE PLAINS BETWEEN PACIFIC
NORTHWEST TROUGH AND DEEPENING TROUGH OVER THE EASTERN CONUS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 528 AM MDT TUE AUG 27 2013
VFR CONDITIONS WILL OCCUR THROUGH THE TAF PERIOD. A SURFACE
TROUGH WILL BE LOCATED NEAR BOTH SITES TODAY AND THIS WILL ALLOW
FOR A WEAKER PRESSURE GRADIENT AND LIGHTER WINDS AS COMPARED TO
THE PREVIOUS TWO DAYS. SOME OCCASIONAL GUSTS BETWEEN 15 AND 20 ARE
POSSIBLE THIS AFTERNOON THROUGH EARLY EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BRB
AVIATION...BRB
AREA FORECAST DISCUSSION
NWS GOODLAND KS
225 AM MDT TUE AUG 27 2013
.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 222 AM MDT TUE AUG 27 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW LARGE SCALE RIDGE STILL
IN PLACE ACROSS THE CENTRAL CONUS. THERE HAS BEEN A GENERAL
WEAKENING OF THE RIDGE CENTER...WITH CURRENT MAX HEIGHT AROUND
595/596DM. A SHORTWAVE TROUGH OVER EASTERN TEXAS SHOWS GOOD
REFLECTION IN BOTH WV AND HEIGHT FIELD AND COULD BE A MINOR FACTOR
IN TEMPS ON WED.
WITH RIDGE WELL ENTRENCHED OVER OUR CWA...THERE WILL BE VERY LITTLE
CHANGE IN THE HOT/DRY CONDITIONS. MODELS SHOW THE SHORTWAVE TROUGH
OVER EASTERN TEXAS ROUNDING SOUTH AND THEN WESTERN EDGE OF THE RIDGE
CENTER THROUGH WED NIGHT. AS HAS BEEN THE CASE THE LAST FEW
DAYS...THERE SHOULD BE GOOD FORCING AND AT LEAST SOME ELEVATED
INSTABILITY WITH THIS FEATURE. MODEL SOUNDINGS STILL SHOW DEEP DRY
AIR MASS IN PLACE...SO OTHER THAN A BRIEF INCREASE IN CLOUDS AND
SLIGHTLY COOLER TEMPS ALOFT I AM NOT ANTICIPATING PRECIP WITH THIS
FEATURE OVER OUR CWA. GENERAL TREND WILL BE A WEAKENING OF THE LEE
TROUGH WITH GRADIENT SHIFTING EASTWARD. THIS SHOULD SUPPORT LESS
WINDY CONDITIONS THROUGH THE REST OF THE FORECAST PERIOD...THOUGH A
FEW GUSTS IN THE 20-30MPH CANT BE RULED OUT THIS AFTERNOON WITH PEAK
MIXING.
REGARDING TEMPS THROUGH THURSDAY...IT LOOKS LIKE A CONTINUATION OF
THE LAST FEW DAYS WITH HIGHS GENERALLY IN THE UPPER 90S/LOW 100S. THE
ONE EXCEPTION WILL BE WED WHEN HIGHS MAY BE ABOUT 5-7F
COOLER...WHICH STILL PUTS HIGHS ACROSS THE CWA IN THE MID-UPPER 90S
FOR MANY LOCATIONS.
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 222 AM MDT TUE AUG 27 2013
MEDIUM RANGE MODEL CONSENSUS IS FOR GRADUAL SLIGHT WEAKENING OF THE
UPPER RIDGE EARLY IN EXTENDED PERIOD. A RELATIVELY SIGNIFICANT
SHORTWAVE TROUGH WILL MOVE ACROSS THE NORTHERN PLAINS AND GREAT LAKES
REGION OVER THE WEEKEND ALONG THE NORTHERN EDGE OF THE RIDGE. AN
ASSOCIATED COLD FRONT WILL MOVE SOUTH/SOUTHWESTWARD TOWARD THE AREA.
THE NEW 00Z ECMWF IS STRONGER WITH THIS SHORTWAVE AND PROGRESSES THE
COLD FRONT FURTHER SOUTHWEST INTO OUR AREA LATE SUNDAY INTO MONDAY.
THE GFS IS LESS AGGRESSIVE WITH SOUTH/SOUTHWEST PROGRESSION OF THE
COLD FRONT BUT DOES SHOW AN INCREASE IN DEEP MOISTURE ACROSS THE
AREA SUNDAY AND MONDAY WITH PWAT VALUES SLIGHTLY EXCEEDING
CLIMATOLOGY. THIS IS ENOUGH TO JUSTIFY KEEPING AT LEAST A VERY LOW
POP IN THE NORTHERN PORTION OF THE FORECAST AREA SUNDAY AND MONDAY.
BY LATE MONDAY A MORE HIGHLY AMPLIFIED PATTERN EVOLVES WITH UPPER
RIDGE STRENGTHENING ONCE AGAIN OVER THE PLAINS BETWEEN PACIFIC
NORTHWEST TROUGH AND DEEPENING TROUGH OVER THE EASTERN CONUS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1106 PM MDT MON AUG 26 2013
VFR CONDITIONS ARE EXPECTED AT BOTH KGLD AND KMCK THROUGH THE TAF
PERIOD. WINDS AT KMCK WILL GRADUALLY DIMINISH OVERNIGHT.
OTHERWISE...WINDS ON TUESDAY WILL NOT BE AS STRONG AS THE PAST FEW
DAYS WITH THE SURFACE TROUGH MOVING INTO THE AREA AND REDUCING THE
PRESSURE GRADIENT.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BRB
AVIATION...024
AREA FORECAST DISCUSSION
NWS JACKSON KY
140 PM EDT TUE AUG 27 2013
.UPDATE...
ISSUED AT 130 PM EDT TUE AUG 27 2013
UPDATED THE FORECAST TO ADD SOME ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS TO THE FORECAST FOR TODAY AND TONIGHT. THE NAM BUFR
SOUNDING FOR JKL FOR TODAY WAS SHOWING CAPE ABOVE 2K JOULES AND LOTS
OF INSTABILITY. THE AIRMASS IS PRIMED AND WAITING FOR A TRIGGER. ALSO
MADE SOME CHANGES FOR WEDNESDAY AND WEDNESDAY NIGHT TO BETTER MATCH
UP WITH NEIGHBORING OFFICES. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 652 AM EDT TUE AUG 27 2013
FORECAST IS ON TRACK THIS MORNING...SO NO CHANGES WARRANTED. IT IS
INTERESTING TO NOTE THAT THE LATEST HRRR RUN DOES HINT AT SOME SHOWER
ACTIVITY DRIFTING INTO FAR NORTHEASTERN KENTUCKY THIS EVENING (AFTER
20Z). CONFIDENCE IS STILL WEAK TO INTRODUCE POPS AT THIS TIME...BUT
MAY NEED TO TAKE A CLOSER LOOK AT THE NEED FOR RAIN CHANCES LATER
THIS MORNING IF THE MODELS REMAIN INSISTENT ON BRINGING SOME RAIN
INTO THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 257 AM EDT TUE AUG 27 2013
SURFACE/MID/UPPER LEVEL RIDGING WILL CONTINUE TO PROVIDE ANOTHER
QUIET WEATHER DAY ACROSS EASTERN KENTUCKY TODAY. THERE IS A MCS
DROPPING SOUTHEAST ACROSS NORTHERN LAKE MICHIGAN THIS MORNING. THIS
SYSTEM WILL LIKELY WEAKEN AND DISSIPATE AFTER SUNRISE...BUT
SHOWERS/STORMS COULD REDEVELOP ASSOCIATED WITH THE MCV THIS AFTERNOON
INTO THIS EVENING. FORTUNATELY...THE TRAJECTORY SHOULD KEEP THIS
COMPLEX TO OUR NORTHEAST...ALLOWING US TO ENJOY ANOTHER PRECIPITATION
FREE DAY AS OUR AREA REMAINS CAPPED. THE QUIET CONDITIONS WILL
PERSIST INTO TONIGHT WITH MORE VALLEY FOG ANTICIPATED AS DEW POINTS
CONTINUE TO CREEP UPWARDS. A SHORTWAVE TROUGH WILL DROP SOUTHEAST AS
THE RIDGE BREAKS DOWN ON WEDNESDAY. THE TIMING REMAINS IN QUESTION
WITH THIS SYSTEM...BUT OPTING TO GO WITH A COMPROMISE WHICH WOULD
BRING THE SYSTEM INTO EASTERN KENTUCKY LATE IN THE DAY. THIS SHOULD
ALLOW FOR MAINLY A DRY DAY FOR WEDNESDAY WITH THE THREAT OF RAIN
ARRIVING LATE. THERE IS SOME WIND SHEAR PRESENT WEDNESDAY EVENING AND
WITH MODEST INSTABILITY...WE COULD SEE A MARGINAL THREAT FOR
STRONG/DAMAGING WINDS AS SHOWERS AND STORMS PUSH SOUTH/SOUTHEAST.
WILL CONTINUE TO CUT 5 TO 6 DEGREES OFF OF MOS GUIDANCE AS IT HAS
REMAINED MUCH TOO WARM OVER THE PAST SEVERAL DAYS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 455 AM EDT TUE AUG 27 2013
A COLD FRONT WITH A WEAK LOW PRESSURE WAVE ALONG IT WILL DROP SOUTH
THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY MORNING UNDER NW FLOW
ALOFT. THE OCCURRENCE OF PRECIP REMAINS PROBLEMATIC...WITH CONVECTION
NEEDING TO OVERCOME FAIRLY WARM MID LEVEL TEMPS. IT IS MOST LIKELY
FURTHER TO OUR EAST WITH LIFT BEING AIDED ALONG A WARM FRONT. WILL
CARRY 20-40 PERCENT POPS LOCALLY. PRECIP COULD LINGER INTO THURSDAY
MORNING AS THE FRONTS EXITS TO THE SOUTH. THE EXTENT OF DRYING BEHIND
THE FRONT NOW LOOKS TO BE MUCH MORE IN QUESTION...WITH MODEL RUNS
FROM MONDAY NIGHT ONLY INDICATING MODEST DRYING. IT SHOULD BE ENOUGH
TO RESULT IN DRY WEATHER FROM LATE THURSDAY THROUGH FRIDAY NIGHT.
HOWEVER...THE THREAT OF SHOWERS AND STORMS RETURNS ALREADY ON
SATURDAY AS A STRONG UPPER RIDGE CENTERED TO OUR WEST WEAKENS AND
MID LEVELS COOL SLIGHTLY...AND OUR LOW LEVEL FLOW BEGINS TO PICK UP
FROM THE S AND SW AND BRINGS SLIGHTLY MORE MOIST LOW LEVEL AIR BACK
INTO THE AREA. HAVE USED SLIGHT CHANCE POPS ON SATURDAY AND AGAIN
SUNDAY INTO SUNDAY NIGHT. THE WARM/MOIST ADVECTION PERSISTS INTO
MONDAY...WHEN ANOTHER COLD FRONT APPROACHES FROM THE NW. HAVE USED A
LOW CHANCE POP WITH THE APPROACH OF THE FRONT ON MONDAY. TEMPS WILL
BE VERY WARM THROUGH THE PERIOD...BUT BASED ON A MODEL BLEND...HAVE
UNDERCUT GFS MEXMOS A BIT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 130 PM EDT TUE AUG 27 2013
VFR CONDITIONS SHOULD PERSIST THROUGH THE REMAINDER OF THE DAY AND
INTO TONIGHT. THERE MAY BE SOME TEMPO MVFR VICINITY OF THE STRONGER
SHOWERS AND THUNDERSTORMS. SOME SHOWERS ARE ALREADY POPPING UP IN
FLOYD AND PIKE COUNTIES THIS AFTERNOON. THEY SHOULD BE ISOLATED TO
SCATTERED. THERE IS LOTS OF POTENTIAL ENERGY IN THESE STORMS...SO
THERE COULD BE SOME STRONGER THAN NORMAL LLWS WITH THESE
THUNDERSTORMS. GOING WITH PERSISTENCE FOR THE FOG TONIGHT. THERE
SHOULD ONLY BE MVFR FOR A SHORT TIME IN THE MORNING.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
652 AM EDT TUE AUG 27 2013
.UPDATE...
ISSUED AT 652 AM EDT TUE AUG 27 2013
FORECAST IS ON TRACK THIS MORNING...SO NO CHANGES WARRANTED. IT IS
INTERESTING TO NOTE THAT THE LATEST HRRR RUN DOES HINT AT SOME SHOWER
ACTIVITY DRIFTING INTO FAR NORTHEASTERN KENTUCKY THIS EVENING (AFTER
20Z). CONFIDENCE IS STILL WEAK TO INTRODUCE POPS AT THIS TIME...BUT
MAY NEED TO TAKE A CLOSER LOOK AT THE NEED FOR RAIN CHANCES LATER
THIS MORNING IF THE MODELS REMAIN INSISTENT ON BRINGING SOME RAIN
INTO THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 257 AM EDT TUE AUG 27 2013
SURFACE/MID/UPPER LEVEL RIDGING WILL CONTINUE TO PROVIDE ANOTHER
QUIET WEATHER DAY ACROSS EASTERN KENTUCKY TODAY. THERE IS A MCS
DROPPING SOUTHEAST ACROSS NORTHERN LAKE MICHIGAN THIS MORNING. THIS
SYSTEM WILL LIKELY WEAKEN AND DISSIPATE AFTER SUNRISE...BUT
SHOWERS/STORMS COULD REDEVELOP ASSOCIATED WITH THE MCV THIS AFTERNOON
INTO THIS EVENING. FORTUNATELY...THE TRAJECTORY SHOULD KEEP THIS
COMPLEX TO OUR NORTHEAST...ALLOWING US TO ENJOY ANOTHER PRECIPITATION
FREE DAY AS OUR AREA REMAINS CAPPED. THE QUIET CONDITIONS WILL
PERSIST INTO TONIGHT WITH MORE VALLEY FOG ANTICIPATED AS DEW POINTS
CONTINUE TO CREEP UPWARDS. A SHORTWAVE TROUGH WILL DROP SOUTHEAST AS
THE RIDGE BREAKS DOWN ON WEDNESDAY. THE TIMING REMAINS IN QUESTION
WITH THIS SYSTEM...BUT OPTING TO GO WITH A COMPROMISE WHICH WOULD
BRING THE SYSTEM INTO EASTERN KENTUCKY LATE IN THE DAY. THIS SHOULD
ALLOW FOR MAINLY A DRY DAY FOR WEDNESDAY WITH THE THREAT OF RAIN
ARRIVING LATE. THERE IS SOME WIND SHEAR PRESENT WEDNESDAY EVENING AND
WITH MODEST INSTABILITY...WE COULD SEE A MARGINAL THREAT FOR
STRONG/DAMAGING WINDS AS SHOWERS AND STORMS PUSH SOUTH/SOUTHEAST.
WILL CONTINUE TO CUT 5 TO 6 DEGREES OFF OF MOS GUIDANCE AS IT HAS
REMAINED MUCH TOO WARM OVER THE PAST SEVERAL DAYS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 455 AM EDT TUE AUG 27 2013
A COLD FRONT WITH A WEAK LOW PRESSURE WAVE ALONG IT WILL DROP SOUTH
THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY MORNING UNDER NW FLOW
ALOFT. THE OCCURRENCE OF PRECIP REMAINS PROBLEMATIC...WITH CONVECTION
NEEDING TO OVERCOME FAIRLY WARM MID LEVEL TEMPS. IT IS MOST LIKELY
FURTHER TO OUR EAST WITH LIFT BEING AIDED ALONG A WARM FRONT. WILL
CARRY 20-40 PERCENT POPS LOCALLY. PRECIP COULD LINGER INTO THURSDAY
MORNING AS THE FRONTS EXITS TO THE SOUTH. THE EXTENT OF DRYING BEHIND
THE FRONT NOW LOOKS TO BE MUCH MORE IN QUESTION...WITH MODEL RUNS
FROM MONDAY NIGHT ONLY INDICATING MODEST DRYING. IT SHOULD BE ENOUGH
TO RESULT IN DRY WEATHER FROM LATE THURSDAY THROUGH FRIDAY NIGHT.
HOWEVER...THE THREAT OF SHOWERS AND STORMS RETURNS ALREADY ON
SATURDAY AS A STRONG UPPER RIDGE CENTERED TO OUR WEST WEAKENS AND
MID LEVELS COOL SLIGHTLY...AND OUR LOW LEVEL FLOW BEGINS TO PICK UP
FROM THE S AND SW AND BRINGS SLIGHTLY MORE MOIST LOW LEVEL AIR BACK
INTO THE AREA. HAVE USED SLIGHT CHANCE POPS ON SATURDAY AND AGAIN
SUNDAY INTO SUNDAY NIGHT. THE WARM/MOIST ADVECTION PERSISTS INTO
MONDAY...WHEN ANOTHER COLD FRONT APPROACHES FROM THE NW. HAVE USED A
LOW CHANCE POP WITH THE APPROACH OF THE FRONT ON MONDAY. TEMPS WILL
BE VERY WARM THROUGH THE PERIOD...BUT BASED ON A MODEL BLEND...HAVE
UNDERCUT GFS MEXMOS A BIT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 652 AM EDT TUE AUG 27 2013
AFTER SOME MORNING VALLEY FOG...VFR CONDITIONS WILL RETURN BY MID
MORNING AND PERSIST THROUGH THE REMAINDER OF THE DAY AND INTO
TONIGHT. MORE VALLEY FOG IS ANTICIPATED TONIGHT...WITH SOME MVFR
VISIBILITIES DEVELOPING AT KSME AND KLOZ AGAIN.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
740 PM EDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM EDT WED AUG 28 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER
THE CNTRL CONUS RESULTING IN ACYC FLOW FROM THE NRN PLAINS THROUGH
THE UPPER MS VALLEY AND GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM
NEAR CYPL-CYHD INTO NW MN SUPPORTED SOME SCT SHRA/TSRA. A MORE
SIGNIFICANT UPSTREAM SHRTWV WAS MOVING FROM IDAHO INTO WRN MONTANA.
MID CLOUDS OVER MN INTO NW WI LEFTOVER FROM EARLIER CONVECTION AND A
WAA PATTERN UPSTREAM...WERE SPREADING INTO WRN UPPER MI. AT THE
SFC...A WEAK RIDGE FROM NRN ONTARIO INTO UPPER MI HAS BROUGHT MOSTLY
CLEAR SKIES AND LIGHT WINDS ACROSS UPPER MI AND PROMINENT LAKE
BREEZES. INLAND...MIXING IN THE SLIGHTLY DRIER AIRMASS PWAT AROUND
1.0 INCH (NEAR NORMAL) HAS DROPPED DEWPOINTS TO AROUND 60F.
WITH MAINLY CLEAR SKIES AND LIGHT WINDS...SOME FOG WILL DEVELOP
OVERNIGHT. HOWEVER...THERE HAS BEEN ENOUGH LOW LEVEL DRYING SO THAT
THE FOG IS NOT EXPECTED TO BECOME AS DENSE OR WIDESPREAD AS LAST
NIGHT. IN ADDITION...SOME MID CLOUDS MOVING INTO THE WEST MAY ALSO
LIMIT THE RADIATIONAL COOLING. OTHERWISE...MIN TEMPS SHOULD AGAIN
DROP TO AROUND 60 INLAND WITH LOWER TO MID 60S ALONG THE GREAT
LAKES.
AS THE NRN ROCKIES SHORTWAVE MOVES THROUGH SRN SASK AND MANITOBA TO
NRN MN WAA AHEAD OF THE SYSTEM WILL BRING INCREASING CLOUDS ACROSS
THE CWA. SOME SHRA/TSRA SUPPORTED BY 310K-315K ISENTROPIC ASCENT
NORTH OF A WARM FRONT INTO SRN MN MAY BRING SOME SHRA/TSRA FROM WRN
LAKE SUPERIOR AND NW WI INTO THE FAR WEST LATE. HOWEVER...ONLY LOW
END POPS WERE INCLUDED AS THE BULK OF ANY PCPN IS EXPECTED TO HOLD
OFF UNTIL AFT 00Z.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 431 PM EDT WED AUG 28 2013
ONE OF THE CONCERNS INHIBITING WIDESPREAD CONVECTION THURSDAY NIGHT
WILL BE THE FACT THAT THE SFC LOW/MAIN TROUGH WILL REMAIN TO OUR S.
SO WHILE THE SHORTWAVE CROSSES UPPER MI...STORMS MAY BE A BIT MORE
ELEVATED. THE LATEST NON-EURO RUNS DO INDICATE THE POTENTIAL FOR
MODERATE TO HEAVY RAIN...PRIMARILY ACROSS LAKE SUPERIOR...WITH 2-3IN
FALLING SOMEWHERE ACROSS THE CWA. EXACT TIMING AND PLACEMENT OF THE
HEAVIER RAIN WILL NEED TO BE PINNED DOWN A BIT LATER. THERE WAS
ENOUGH CERTAINTY TO KEEP LIKELY POPS GOING OVER THE FAR W LATE
THURSDAY EVENING...AND ACROSS MUCH OF THE W HALF OVERNIGHT...BEFORE
CONTINUING THE TRACK AROUND THE 500MB RIDGE AND SHIFTING TO OUR SE
FRIDAY MORNING. THE MOST UNSTABLE AIR WILL LIKELY BE ACROSS THE
INTERIOR W AND TO OUR SW...CLOSER TO THE SFC LOW.
A TEMPORARY RIDGE WILL EXPAND ACROSS THE UPPER GREAT LAKES FRIDAY
EVENING AS THE SFC LOW STRETCHING FROM N LAKE MI TO E IA EXITS
ACROSS LOWER MI. DIMINISHED THE CHANCE OF SHOWERS/TS FOR FRIDAY
NIGHT AND SATURDAY...AHEAD OF THE DEEPENING CANADIAN LOW. THE SFC
LOW IS STILL FIGURED TO BE OVER LAKE WINNIPEG AROUND 12Z
SATURDAY...AND SHIFT ACROSS S ONTARIO/LAKE SUPERIOR SUNDAY
MORNING-AFTERNOON. THE ECMWF IS REMAINS THE DEEPEST AT THE SFC AND
ALOFT WITH THIS FEATURE...BUT THE 12Z GFS IS CATCHING UP. WILL
CONTINUE TO LEAN THE FCST A BIT CLOSER TO THE ECMWF SOLUTION FOR
MUCH OF THIS PERIOD. QUICKER THAN ITS RUN FROM YESTERDAY...THE 12Z
ECMWF DEVELOPS THE 500MB LOW OVER ONTARIO SUNDAY MORNING /ABOUT
18HRS FASTER THAN THE GFS/. THIS WILL BE THE START OF OUR NEAR TO
BELOW NORMAL TEMPERATURES...AS ANOTHER LOW DIVES INTO EASTERN CANADA
ON WEDNESDAY. THE RESULT WILL BE A SIGNIFICANT TROUGH SUPPRESSING
THE STRONG HIGH TO OUR SW...AND 60S AND LOW 70S RETURNING TO THE
FCST FOR MONDAY...BEFORE MODERATING BACK TO NORMAL /70S/ BY
WEDNESDAY. STRONGER NW WINDS OF 10-20KTS ACROSS LAKE SUPERIOR AND
850MB TEMPS OF 4-6C SHOULD KEEP TEMPS IN THE 60S MONDAY...ALONG WITH
THE POTENTIAL FOR SHOWERS/DRIZZLE NEAR LAKE SUPERIOR. WAY OUT IN THE
FUTURE...THE ECMWF DOES HAVE 0 TO -2C TEMPS ACROSS LAKE SUPERIOR ON
THURSDAY. WILL WILL NEED TO WAIT AND SEE ON THAT ONE. EITHER
WAY...THE WARM AIR LOOKS TO BE DONE FOR A WHILE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 740 PM EDT WED AUG 28 2013
VFR CONDITIONS SHOULD PREVAIL THRU THE EVENING HRS...AND THEN IT
APPEARS FOG WILL DEVELOP UNDER MOSTLY CLEAR SKIES...LIGHT/CALM WIND
AND RELATIVELY MOIST LOW-LEVELS. MAINLY MVFR CONDITIONS ARE EXPECTED
AT KCMX WITH KIWD/KSAW POSSIBLY DOWN TO IFR. MAY SEE SOME BRIEF
PERIODS WITH VIS DOWN TO LIFR/VLIFR. FOG WILL BURN OFF A COUPLE OF
HRS AFTER SUNRISE WITH VFR CONDITIONS TO FOLLOW. THERE MIGHT BE
ISOLD/SCT SHRA/TSRA LATE THU AFTN...BUT CONFIDENCE IN DEVELOPMENT IS
VERY LOW...SO NO MENTION WAS INCLUDED IN FCST.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 PM EDT WED AUG 28 2013
PATCHY FOG WILL PERSIST THROUGH THROUGH THURSDAY AS RELATIVELY HIGH
DEWPOINTS REMAIN THROUGH THE WEEK. DRIER AIR BEGINS MOVING IN FOR
THE WEEKEND... LIMITING FOG POTENTIAL FOR THE WEEKEND. LIGHT WINDS
WILL PREVAIL THROUGH MUCH OF THE FORECAST PERIOD AS THE PRESSURE
GRADIENT REMAINS LIGHT UNDER THE INFLUENCE OF RIDGING ALOFT. THE
PRESSURE GRADIENT WILL TIGHTEN SUNDAY WITH THE PASSAGE OF A LOW
PRESSURE SYSTEM TO THE NORTH OF LAKE SUPERIOR. BEHIND THE COLD
FRONT...NORTHWEST WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 25
KNOT RANGE. WAVES WILL MAY ALSO BUILD INTO THE 3 TO 7 FOOT RANGE
WITH COLDER AIR MOVING IN.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
431 PM EDT TUE AUG 27 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 428 PM EDT TUE AUG 27 2013
WV IMAGERY AND RUC ANALYSIS INDICATED WNW FLOW THROUGH THE NRN GREAT
LAKES ATOP A MID/UPPER LEVEL RIDGE CENTERED OVER MO/KS/AR. NO
SHORTWAVE TROUGHS WERE NOTED UPSTREAM THAT ARE LIKELY TO HAVE A
SIGNIFICANT AFFECT ON UPPER MICHIGAN. AT THE SFC...A WEAK
TROUGH/FRONT EXTENDED FROM NEAR MNM TO MSP WITH WEAK HIGH PRES TO
THE NW OF LAKE SUPERIOR BRINGING LIGHT NE LOW LEVEL FLOW ACROSS LAKE
SUPERIOR. PERSISTENT LOW CLOUDS OVER THE SRN HLF OF THE CWA...HAVE LIMITED
TEMPS AND RESULTANT INSTABILITY DESPITE DEWPOINTS REMAINING AROUND
70. THE LAKE BREEZE FRONT INTO NRN UPPER MI HAS PRODUCED MAINLY JUST
TCU WITH ONLY A FEW SPRINKLES. WHILE THE TSRA ALONG THE 900-700 MB
FGEN ZONE THROUGH S CNTRL UPPER MI HAD MOVED INTO NRN LAKE
MI...ADDITIONAL TSRA WERE DEVELOPING IN NE WI JUST TO THE NORTH OF
THE FRONT WHERE MLCAPE VALUES HAD CLIMBED INTO THE 2K-3K J/KG RANGE.
EXPECT MAINLY JUST ISOLD SHRA AND POSSIBLY A TSRA OVER CNTRL UPPER
MI ALONG THE LAKE BREEZE BOUNDARY LATE THIS AFTERNOON AND EVENING
WHERE INSTABILITY WAS MORE MODEST...ONLY TO NEAR 500-1000 J/KG. THE
STRONGER TSRA ALONG THE FRONT MAY JUST BRUSH THE FAR SRN CWA NEAR
MNM EARLY BUT SHOULD SAG SOUTH OF THE AREA BY 21Z-22Z. ADDITIONAL
ELEVATED SHRA/TSRA NEAR ESC LATE THIS AFTERNOON IN THE AREA OF
WAA/ISENTROPIC LIFT SHOULD ALSO MOVE OFF TO THE SE BY THIS EVENING.
LARGER SCALE SUBSIDENCE WILL THEN TAKE OVER TONIGHT AS WEAK TO
MODERATE 700-300 MB QVECTOR DIV AND SFC HIGH PRES BUILDS OVER THE
AREA. WITH THE LIGHT WINDS AND ABUNDANT LOW LEVEL MOISTURE...AREAS
OF FOG/STRATUS ARE EXPECTED TO DEVELOP. WITH ONLY WEAK DRY ADVECTION
AND DEWPOINTS ONLY DROPPING INTO THE LOWER TO MID 60S...MIN TEMPS
WILL REMAIN WELL ABOVE NORMAL. THE NNE LOW LEVEL FLOW TONIGHT INTO
EARLY WED COULD ALSO BRING FOG/STRATUS INTO LOCATIONS ALONG LAKE
SUPERIOR. AFTER DAYTIME HEATING BURNS OFF ANY LINGERING LOW
CLOUDS...SUNSHINE SHOULD PUSH INLAND TEMPS INTO THE LOWER TO MID 80S
WITH LOWER READINGS IN THE MID TO UPPER 70S ALONG LAKE SUPERIOR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 428 PM EDT TUE AUG 27 2013
SFC HIGH OVERHEAD WEDNESDAY NIGHT SLOWLY SINKING SE THROUGH
FRIDAY...AS A WEAK FRONTAL TROUGH LINGERS ACROSS CENTRAL AND S
ONTARIO. WEDNESDAY NIGHT INTO THURSDAY MORNING STILL LOOK DRY...OUT
AHEAD OF THE NEXT SHORTWAVE OVER S ONTARIO ROUNDING THE SIGNIFICANT
RIDGE DOMINATING MUCH OF THE CENTRAL U.S. IT STILL LOOKS LIKE THE
BEST CHANCE FOR CONVECTION AND MODERATE RAIN WILL BE ALONG AND S OF
THE WI BORDER THURSDAY NIGHT.
LARGE HIGH PRESSURE OVER CENTRAL CANADA WILL SHIFT ACROSS N
ONTARIO ON FRIDAY...LEAVING UPPER MI IN BETWEEN -2 TO -6C AIR OVER S
HUDSON BAY HOTTER 22-25C TEMPERATURES OVER THE CENTRAL PLAINS. WITH
A SERIES OF WEAKER DISTURBANCES SWINGING IN FROM THE NW IT WILL BE
DIFFICULT TO KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS OUT OF
THE FCST FOR FRIDAY AND FRIDAY NIGHT...ALTHOUGH THE LATEST MODEL
GUIDANCE DOES SUGGEST THAT IT COULD BE TRIMMED BACK A BIT MORE THAN
MY LAST MINUTE 20Z UPDATE.
THE SFC LOW CENTERED OVER THE PLAINS WILL SINK TO OUR S ON SATURDAY.
THIS WILL RESTRICT MUCH OF THE HOTTER AIR FROM PUSH ACROSS THE UPPER
GREAT LAKES. THE MAIN STORY WILL BE THE DEEPENING SFC LOW OVER LAKE
WINNIPEG FRIDAY NIGHT/SATURDAY MORNING MOVING ACROSS CENTRAL AND S
ONTARIO SATURDAY NIGHT /BOTTOMING OUT PRESSURE WISE AROUND 997MB/.
THE COLD FRONT IS EXPECTED TO DRAG ACROSS W AND CENTRAL UPPER MI
OVERNIGHT...AND EXIT E UPPER MI SUNDAY MORNING.
THE 27/00Z ECMWF LOOKS TO BE QUICKER AND DEEPER STILL WITH THE
TIMING OF THE 500MB TROUGH SWINGING ACROSS S CENTRAL CANADA AND
SUPPRESSING THE DOMINANT RIDGE TO THE 4-CORNERS REGION...AND IS A
SIGNIFICANT OUTLIER COMPARED TO THE GFS ENSEMBLE MEMBERS. WITH THE
TROUGH FORMING A FULL-FLEDGED LOW OVER SE CANADA MONDAY/MONDAY
NIGHT...UPPER MI WILL BE ABLE TO GET SOME RELIEF FROM THE HEAT.
SINGLE DIGIT 850MB TEMPS WILL SLIDE IN SUNDAY NIGHT...WITH BOTH 12Z
RUNS OF THE ECMWF AND GFS SHOWING 4C MONDAY MORNING.
THE COOLER TEMPERATURES WILL BE SHORT LIVED AS THE HIGH AMPLITUDE
500MB RIDGE OVER THE SOUTHERN STATES EXTENDS ACROSS THE ROCKIES ON
MONDAY...AND PUSHES ACROSS THE N PLAINS/S CENTRAL CANADA AND EDGES
ACROSS THE UPPER GREAT LAKES ON TUESDAY. LOOK FOR 70S AND POSSIBLY
80S TO RETURN AGAIN BY THE MIDDLE OF NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 137 PM EDT TUE AUG 27 2013
DAYTIME HEATING HAS HELPED LIFT CIGS INTO THE MVFR RANGE.
ONCE WINDS BECOME MORE NORTHERLY LATER TODAY...EXPECT LOWER MVFR
CLOUDS TO LOWER TO IFR WITH ADDITIONAL MOISTURE OFF LK SUPERIOR
UPSLOPING INTO KIWD. CONDITIONS MAY LOWER FURTHER THERE TONIGHT.
AS WINDS TURN OFF LK SUPERIOR AT KSAW TONIGHT...CONDITIONS ARE ALSO
EXPECTED TO LOWER TO IFR AT SAW WITH MOIST UPSLOPE FLOW. ENOUGH LOW
LEVEL MOISTURE IS EXPECTED TO LINGER AT CMX WITH LIGHT WINDS AND SOME
RADIATIONAL COOLING FOR CONDITIONS TO DROP BACK INTO THE VLIFR RANGE
TONIGHT.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 428 PM EDT TUE AUG 27 2013
LIMITED PRESSURE GRADIENTS ACROSS LAKE SUPERIOR SHOULD KEEP WINDS
BELOW 20KTS THROUGH THE FORECAST PERIOD. AREAS OF FOG WILL PERSIST
ACROSS MUCH OF LAKE SUPERIOR WITH HIGH DEWPOINTS OVER THE REGION.
AS WINDS TURN TO THE NORTH TONIGHT...EXPECT THE FOG TO PUSH SOUTH
THROUGH WEDNESDAY MORNING AND THEN DIMINISH SOME AS SLIGHTLY DRIER
CANADIAN AIR MOVES SOUTH OVER THE LAKE THROUGH WEDNESDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
358 PM EDT TUE AUG 27 2013
LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE
.SYNOPSIS...
ISSUED AT 358 PM EDT TUE AUG 27 2013
AN AREA OF THUNDERSTORMS WILL PRECEDE THE COLD FRONT EARLY
TONIGHT. SOME STORMS MAY HAVE DAMAGING WINDS AND LARGE HAIL FROM
THESE STORMS. ALSO VERY HEAVY RAINFALL IS POSSIBLE AS THE LINE OF
STORMS MOVES THROUGH THE AREA.
A LARGE CANADIAN HIGH MOVES ACROSS THE AREA WEDNESDAY INTO
THURSDAY BEFORE ANOTHER FRONTAL WAVE MOVES THROUGH THE AREA FRIDAY
WITH A CHANCE OF SCATTERED THUNDERSTORMS. TEMPERATURES WILL
CONTINUE TO BE WARMER THAN NORMAL THROUGH SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 358 PM EDT TUE AUG 27 2013
THE MAIN ISSUE WITH THIS FORECAST IS THE RISK OF STRONG TO SEVERE
STORMS EARLY THIS EVENING AND ALSO THE POTENTIAL FOR FLOODING AS
THE ATMOSPHERE IS VERY MOIST AHEAD OF THE COLD FRONT.
THE COMBINATION OF SHORTWAVE... AN 80 KNOT SPEED MAX ON THE POLAR
JET DIVING SOUTHEAST ACROSS LAKE HURON...AN ASSOCIATED 30 KNOT
LOW LEVEL JET NEAR AND SOUTH OF INTERSTATE 96 FEEDING INTO THE
ASSOCIATED FRONTAL WAVE DIVING SOUTHEAST FROM EASTERN MINNESOTA
WILL FEED ON THE 250O J/KG OF MIXED LAYER CAPE OVER SOUTHERN AND
CENTRAL LOWER MICHIGAN THIS EVENING TO BRING THE POTENTIAL FOR
STRONG TO SEVERE STORMS THIS EVENING OVER MOST OF SOUTHWEST LOWER
MICHIGAN. THERE IS A DIFFERENTIAL HEATING BOUNDARY NEAR ROUTE
10...SOUTH OF WHICH ANY STORMS WOULD BE SURFACE BASED THIS
EVENING. AS THE LINE OF STORMS OVER NORTHWEST LOWER MICHIGAN MOVES
SOUTH OF ROUTE 10 I WOULD EXPECT THE STORMS TO INTENSIFY. WHILE
THE SURFACE WINDS ARE NOT ALL THAT STRONG INTO THE FRONT... THERE
IS A DRY LAYER OF AIR BELOW 800 MB...SEEN ON BOTH THE RAP AND NAM
SOUNDINGS THAT WOULD SUPPORT VERY STRONG WINDS FROM THESE STORMS.
ALSO THERE IS THE THREAT FOR LOCALIZED FLOODING AS PRECIPITABLE
WATER VALUES ARE OVER 2 INCHES WHICH IS MORE THAN 2 STANDARD
DEVIATIONS FROM NORMAL. SO EVEN THROUGH THE STORMS WILL BE MOVING
AROUND 35 TO 40 KNOTS...THE RAIN MAY BE HEAVY ENOUGH TO CAUSE
FLOODING IN URBAN AREA OR AREAS WITH POOR DRAINAGE. ALSO MOST OF
OUR NORTHERN CWA HAD OVER A HALF INCH OF RAIN LAST NIGHT...SOME
AREAS HAD OVER 1 1/2 INCHES SO THE SOIL IS RATHER WET THERE
ALREADY.
ONCE THE STORMS MOVE THROUGH LATER THIS EVENING DRIER AIR MOVES IN
BEHIND THE FRONT BUT THERE IS SOME LOW LEVEL MOISTURE THAT WRAPS
AROUND THE SYSTEM SO EVEN THROUGH THE STORMS SHOULD END... THE
REAL CLEARING OF THE SKY MY TAKE UNTIL MID DAY WEDNESDAY.
HIGH PRESSURE WILL BRING MOSTLY CLEAR SKIES AND LOWER DEW POINTS
WEDNESDAY NIGHT INTO THURSDAY. ANOTHER FRONTAL WAVE MAY BRING MORE
THUNDERSTORMS TO THE AREA LATER THURSDAY NIGHT.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 358 PM EDT TUE AUG 27 2013
UNSEASONABLY WARM AND HUMID CONDITIONS ARE ANTICIPATED FRIDAY AND
SATURDAY. THERE IS A SMALL CHC OF A SHOWER OR STORM FRIDAY AS A WEAK
SHORTWAVE MAY MOVE IN FROM THE WNW AND COMBINE WITH WEAK INSTABILITY
TO CAUSE DEVELOPMENT OF A SHOWER OR TWO.
A BETTER CHANCE FOR SHOWERS AND STORMS SHOULD COME SATURDAY THROUGH
SATURDAY NIGHT ALONG AND OUT AHEAD OF THE APPROACHING COLD FRONT. NW
FLOW CAA WILL COMMENCE BEHIND THE FRONT ON SUNDAY BUT MAX TEMPS
SUNDAY SHOULD STILL REACH THE UPPER 70S TO LOWER 80S. HOWEVER BY
LABOR DAY AND FOR TUESDAY IT WILL BE MUCH COOLER WITH MAX TEMPS
LIKELY STRUGGLING TO REACH THE LOWER 70S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 1255 PM EDT TUE AUG 27 2013
VFR CONDITIONS ARE ANTICIPATED AT ALL THE TERMINALS THIS AFTERNOON.
THUNDERSTORMS ARE EXPECTED TO DEVELOP FROM NORTH TO SOUTH DURING THE
EARLY TO MID EVENING HOURS TONIGHT... MOST LIKELY IMPACTING KMKG TOWARD
22Z... KGRR AND KLAN BY AROUND 00Z AND THE TERMINALS ALONG THE I-94
CORRIDOR BY 01Z-02Z. THESE STORMS MAY CONTAIN GUSTY WINDS...
FREQUENT LIGHTNING AND VERY HEAVY DOWNPOURS.
THE STORMS WILL MOVE OUT LATE THIS EVENING BUT SHOWERS WILL LINGER
OVERNIGHT ALONG WITH DEVELOPMENT OF SOME LOW CLOUDS AND FOG THAT
WILL CAUSE CONDITIONS TO DETERIORATE TO MVFR THEN IFR. CONDITIONS
WILL IMPROVE SLOWLY FROM IFR TO MVFR DURING THE MID TO LATE MORNING
HOURS WEDNESDAY.
&&
.MARINE...
ISSUED AT 358 PM EDT TUE AUG 27 2013
WINDS SHOULD BECOME NORTH AND BE ON THE LIGHT SIDE BEHIND THE
COLD FRONT WEDNESDAY INTO THURSDAY SO I DO NOT SEE MUCH OF AN
ISSUE WITH HAVING TO HAVE A SMALL CRAFT ADVISORY AT THIS POINT.
&&
.HYDROLOGY...
ISSUED AT 358 PM EDT TUE AUG 27 2013
GIVEN THE HIGH PRECIPITABLE WATER VALUES IN THE ATMOSPHERE AHEAD
OF THE COLD FRONT THERE IS THE POTENTIAL FOR FLOODING OF AREAS
WITH POOR DRAINAGE. SOME LOCALIZED AREAS COULD SEE OVER AN INCH OF
RAIN IN LESS THAN AN HOUR WITH THE STRONGER STORMS... THAT SORT OF
RAINFALL RATE WOULD BE A PROBLEM IN URBAN AREA.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
129 PM EDT TUE AUG 27 2013
.AVIATION...
//DISCUSSION...
CONVECTION STILL ONGOING OVER NORTHERN LOWER MICHIGAN AND CONTINUES
TO SLOWLY MOVE TO THE SOUTHEAST AS IT DIMINISHES. MBS STANDS THE
BEST CHANCE AT SEEING PRECIPITATION THIS AFTERNOON AND HAVE INCLUDED
THAT IN THE TAF. EXPECTING STORMS TO RE-FIRE AFTER 00Z AS AREAS OF
VORTICITY CONTINUE TO SLIDE DOWN OVER THE UPPER LEVEL RIDGE AND THE
LOW LEVEL JET GETS GOING THIS EVENING...AS WHAT HAS BEEN SEEN THE
PAST FEW DAYS. TIMING OF STORMS STILL LOOKING TO BE IN THE 03Z TO
06Z TIMEFRAME FOR DTW/YIP/DET...WITH SCATTERED SHOWERS OVERNIGHT.
MAIN THREATS WITH STORMS WILL BE WINDS AND HEAVY RAIN. MAIN
CHALLENGE WITH RESPECT TO SEVERE WEATHER REMAINS ON WHETHER THE
CLOUDS CAN THIN ENOUGH TO ALLOW FOR INCREASED INSTABILITY ACROSS THE
AREA.
FOR DTW...SHOWERS AND STORMS FROM UPSTREAM MCS EXPECTED TO CONTINUE
TO DIMINISH AS IT MOVES TO THE SOUTHEAST. THERE IS SLIGHT POTENTIAL
FOR SOME OF THE SHOWERS TO HOLD TOGETHER...HOWEVER CONFIDENCE IS TOO
LOW AT THIS POINT TO MENTION IN THE TAFS FOR THE AFTERNOON AND WILL
CONTINUE TO MONITOR TRENDS. CLOUDS WILL REMAIN WITH CONVECTION
EXPECTED TO REDEVELOP AROUND 03Z.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORM POTENTIAL AFTER 00Z.
* MEDIUM CONFIDENCE IN CEILINGS FALLING BELOW 5000 FT WEDNESDAY
MORNING.
&&
.PREV DISCUSSION...ISSUED 1124 AM EDT TUE AUG 27 2013
UPDATE...
MORNING CONVECTION HAS SINCE MOVED OFF TO THE SOUTHEAST...LEAVING
SE MI INBETWEEN TWO AREAS OF CONVECTION. THE AREA OF CONCERN FOR
THIS AFTERNOON IS THE ONGOING CONVECTION CURRENTLY MOVING OVER
NORTHERN LOWER MICHIGAN. PRECIP FROM THE UPSTREAM MCS HAS BEEN
DIMINISHING AS IT MOVES INTO DRIER AIR AS SEEN ON THE 12Z APX
SOUNDING. LATEST HRRR RUN CONTINUES TO ADVERTISE THE PROGRESSION
OF CONVECTION ACROSS SE MI...WITH REDEVELOPMENT OF STORMS AFTER
00Z. LATEST MESOANALYSIS AND SATELLITE DOES SHOW MORE MODEST CAPE
VALUES OVER WESTERN PORTIONS OF MICHIGAN WHERE CLOUDS HAVE BEEN
ABLE TO BREAK. THE BETTER CHANCE FOR SEVERE WEATHER IS STILL
EXPECTED TO BE AFTER 00Z...HOWEVER THIS WILL BE DEPENDENT ON HOW
CURRENT SHOWERS HOLD TOGETHER THROUGH THE EARLY AFTERNOON AND
AMOUNT OF INSTABILITY THAT BUILDS ACROSS THE AREA THIS EVENING. STILL
LOOKING AT MAIN THREATS WITH ANY STORMS BEING WINDS AND HEAVY
RAIN.
PREV DISCUSSION...ISSUED 347 AM EDT TUE AUG 27 2013
SHORT TERM... TODAY AND TONIGHT
LARGER SCALE ENVIRONMENT REMAINS VIRTUALLY A CARBON COPY OF THAT
NOTED 24 HOURS AGO...SE MICHIGAN RESIDING ALONG THE NORTHEAST FLANK
OF STRONG UPPER RIDGING ANCHORED OVER THE CENTRAL PLAINS.
WELL-DEFINED THETA-E/MOISTURE AXIS EMANATING SOUTHEAST OF THE MAIN
MOISTURE PLUME SITUATED OVER THE UPPER MS VALLEY NOW DRAPED ACROSS
FAR SOUTHEAST MICHIGAN. EARLY DAY FOCUS TARGETS THE INBOUND
CONVECTIVE COMPLEX CURRENTLY WORKING ACROSS NORTHERN LAKE MICHIGAN.
RECENT RADAR/SATELLITE TRENDS AND HI RES MODEL GUIDANCE SUGGEST SOME
FORM OF THIS COMPLEX WILL WORK ACROSS SE MICHIGAN THIS MORNING
/MAINLY M-59 NORTHWARD/. WHILE THE ARRAY OF MODEL GUIDANCE PROVIDE
A MIXED SIGNAL ON THE RESPONSE...THERE IS A MORE CONCERTED EXPANSION
NOTED AS THE ASSOCIATED MID LEVEL WAVE WORKS ACROSS THE EXISTING
HIGHER THETA-E PLUME. THE MORNING TIMING IS CERTAINLY NOT
IDEAL...BUT RECENT SPC MESOANALYSIS DOES REVEAL ROUGHLY 1000 J/KG OF
EXISTING MUCAPE ALONG AND SOUTHWEST OF A TRI-CITIES TO MOUNT CLEMENS
LINE. THIS WILL SUPPORT A HIGHER END POP /ESPECIALLY NORTH/...WITH
A SMALL WINDOW FOR A FEW STRONGER CELLS TO EMERGE BEFORE THE ENTIRE
COMPLEX EXITS TO THE SOUTHEAST BY LATE MORNING.
BRIEF PERIOD OF SUBSIDENCE AND SOME LAGGING RESIDENCE TIME TO THE
ASSOCIATED CIRRUS CANOPY WILL CONTAIN THE DEGREE OF DESTABILIZATION
FOR A PERIOD OF TIME INTO MIDDAY. HOWEVER...RENEWED THETA-E/WARM
AIR ADVECTION WILL COMMENCE IN THE WAKE OF THIS WAVE AS SOUTHWEST
LOW LEVEL FLOW STRENGTHENS THROUGH THE AFTERNOON AND EVENING. THIS
WILL BE SUFFICIENT FOR A SOLID LATE DAY DIURNAL RESPONSE...HIGHS
SETTLING INTO THE MIDDLE AND UPPER 80S. MUCH LIKE THIS PAST
EVENING...THIS PROCESS ALONE MAY PROVE ADEQUATE TOWARD GENERATING
WIDELY SCATTERED CONVECTION AS INSTABILITY BUILDS. A FIRM CAP WILL
REMAIN PROBLEMATIC...SO BETTER COVERAGE WOULD BE A STRUGGLE UNDER
THIS ENVIRONMENT. THERE IS SUPPORT FOR ANOTHER RIDGE CRESTING
SHORTWAVE TO ANCHOR ANOTHER ROUND OF CONVECTION ACROSS THE UPPER MS
VALLEY AT THE SAME TIME. SLIGHTLY BETTER DIURNAL DYNAMIC RESPONSE
ATTENDANT WITH THIS WAVE...WITH MAINTENANCE AND POSSIBLE UPSCALE
GROWTH EXPECTED ALONG THE MAIN INSTABILITY GRADIENT BACKED BY A
30-35 KNOT VEERING LOW LEVEL JET. 850-300 MB MEAN FLOW AND
PROJECTED CORFIDI VECTORS AGAIN PRESENT LOWER MICHIGAN IN A
FAVORABLE DOWNSTREAM POSITION...MOST FAVORED TIME TONIGHT WITHIN THE
00Z-07Z WINDOW. ORGANIZED CONVECTION BEHIND BULK SHEAR VALUES IN
EXCESS 30 KNOTS WILL BRING THE RISK OF STRONGER WIND GUSTS. A HIGH
PWAT AIRMASS WILL ALSO CONTRIBUTE TO POSSIBLE LOCALLY HEAVY
RAINFALL.
LONG TERM...WEDNESDAY THROUGH MONDAY
WEATHER OVER MICHIGAN WILL CONTINUE TO BE DOMINATED BY FLOW OVER THE
TOP OF THE LARGE UPPER RIDGE OVER THE CENTRAL PLAINS...BEFORE WE
START TO SEE SOME NORTHERN STREAM CONTRIBUTIONS OVER THE HOLIDAY
WEEKEND.
AREA OF LOW PRESSURE AND WEAK FRONT WILL CONTINUE TO DROP THROUGH
SOUTHERN LOWER MICHIGAN WEDNESDAY MORNING. GFS FORECAST SOUNDINGS
FOR DTW START TO SHOW SIGNIFICANT DRYING AND A CAP FORMING AS HIGH
PRESSURE BUILDS IN AFTER 18Z...AND WILL KEEP LOW CHANCES FOR
SHOWERS/TSTORMS ALONG/SOUTH OF M-59 ONLY THROUGH MID-DAY. MODELS
THEN REMAIN IN STRONG AGREEMENT WITH SURFACE HIGH PRESSURE BUILDING
INTO THE CENTRAL GREAT LAKES WEDNESDAY NIGHT THROUGH
THURSDAY...KEEPING THE WEATHER DRY. AIRMASS WILL REMAIN WARM EVEN
BEHIND THE FRONT WITH H850 TEMPERATURES ONLY COOLING TO 16-18 C FOR
WEDNESDAY AND THURSDAY. WITH GOOD INSOLATION THIS SHOULD KEEP
TEMPERATURES IN THE LOW AND MID 80S BOTH DAYS...SLIGHTLY COOLER
OVER THE THUMB WHERE FLOW WILL BE OFF LAKE HURON.
MODELS HAVE THEN KEYED IN ON A SHORTWAVE WITH ORIGINS OVER THE
DESERT SOUTHWEST THEN RIDING ATOP THE RIDGE AND ACROSS NORTHERN
MICHIGAN LATE THURSDAY NIGHT AND FRIDAY. THIS SETUP INITIALLY LOOKS
SLIGHTLY SIMILAR TO TODAY...A FRONT SETTLING IN OVER MICHIGAN AS
UPPER ENERGY OVER CANADA PUSHES SURFACE LOW PRESSURE TOWARDS THE
AREA. THERE ARE STILL QUITE A FEW DIFFERENCES BETWEEN THE MODELS
HOWEVER...BUT THE GENERAL IDEA IS FOR THIS INITIAL WAVE AND
POTENTIALLY A FEW OTHERS TO RIDE OVER THE FRONTAL BOUNDARY THAT WILL
BE DRAPED OVER THE REGION. THIS WILL PROVIDE A CHANCE FOR SHOWERS
AND THUNDERSTORMS FRIDAY AND SATURDAY. THE BIG DIFFERENCE BETWEEN
TODAY`S PATTERN AND THE SET-UP FOR LATER IN THE WEEK WILL BE A
FAIRLY STRONG UPPER TROUGH PUSHING THROUGH CENTRAL CANADA AND
ARRIVING INTO THE GREAT LAKES ON EITHER SATURDAY OR SUNDAY. WHILE
GFS AND EURO DIFFER WITH THE OVERALL SET-UP AND TIMING...THEY DO
AGREE WITH PUSHING A STRONG COLD FRONT DOWN ACROSS THE AREA ON
SUNDAY...PROVIDING A CONTINUATION OF CHANCES FOR SHOWERS/TSTORMS.
DRIER AIRMASS SHOULD WORK INTO THE AREA BEHIND THE FRONT...GFS
ACTUALLY HAS A SECONDARY FRONT DROPPING THROUGH ON MONDAY NOW AS
HIGH PRESSURE SETTLES DOWN INTO THE AREA. TEMPERATURES LOOK TO
REMAIN WARM WITH ABOVE NORMAL TEMPERATURES INTO THE
WEEKEND...ALTHOUGH CONVECTION COULD LIMIT HEATING AT TIMES.
TEMPERATURES SHOULD THEN COOL BEHIND THE FRONT FOR LABOR DAY...WITH
CURRENT FORECAST CARRYING MAX TEMPS ONLY IN THE 70S.
MARINE...
MOIST AND UNSTABLE ENVIRONMENT WILL SUPPORT THUNDERSTORM DEVELOPMENT
THROUGH TONIGHT. OUTSIDE OF THIS THUNDERSTORM RISK...MARINE
CONDITIONS WILL REMAIN QUITE FAVORABLE THROUGH WEDNESDAY.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SS
UPDATE.......SS
SHORT TERM...MR
LONG TERM....HLO
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1124 AM EDT TUE AUG 27 2013
.UPDATE...
MORNING CONVECTION HAS SINCE MOVED OFF TO THE SOUTHEAST...LEAVING
SE MI INBETWEEN TWO AREAS OF CONVECTION. THE AREA OF CONCERN FOR
THIS AFTERNOON IS THE ONGOING CONVECTION CURRENTLY MOVING OVER
NORTHERN LOWER MICHIGAN. PRECIP FROM THE UPSTREAM MCS HAS BEEN
DIMINISHING AS IT MOVES INTO DRIER AIR AS SEEN ON THE 12Z APX
SOUNDING. LATEST HRRR RUN CONTINUES TO ADVERTISE THE PROGRESSION
OF CONVECTION ACROSS SE MI...WITH REDEVELOPMENT OF STORMS AFTER
00Z. LATEST MESOANALYSIS AND SATELLITE DOES SHOW MORE MODEST CAPE
VALUES OVER WESTERN PORTIONS OF MICHIGAN WHERE CLOUDS HAVE BEEN
ABLE TO BREAK. THE BETTER CHANCE FOR SEVERE WEATHER IS STILL
EXPECTED TO BE AFTER 00Z...HOWEVER THIS WILL BE DEPENDENT ON HOW
CURRENT SHOWERS HOLD TOGETHER THROUGH THE EARLY AFTERNOON AND
AMOUNT OF INSTABILITY THAT BUILDS ACROSS THE AREA THIS EVENING. STILL
LOOKING AT MAIN THREATS WITH ANY STORMS BEING WINDS AND HEAVY
RAIN.
&&
.AVIATION...ISSUED 710 AM EDT TUE AUG 27 2013
//DISCUSSION...
THUNDERSTORM COMPLEX WILL CONTINUE ACROSS SOUTHEAST MICHIGAN THIS
MORNING. MAIN THREAT FOR THUNDERSTORMS CURRENTLY ANCHORED ALONG THE
LEAD EDGE OF THIS COMPLEX WILL PULL EAST OF ALL TERMINALS OVER THE
NEXT HOUR. A PERIOD OF RAINFALL WITH SOME EMBEDDED THUNDER WILL
LINGER THROUGH LATE MORNING...PROVIDING A WINDOW FOR SOME
INTERMITTENT MVFR VISIBILITY RESTRICTIONS. THE EXISTENCE OF A MOIST
AND WEAKLY UNSTABLE ENVIRONMENT WILL MAINTAIN THE CHANCE FOR
THUNDERSTORM DEVELOPMENT BOTH UPSTREAM AND OVERHEAD FROM MID
AFTERNOON INTO TONIGHT. ANOTHER THUNDERSTORM COMPLEX CURRENTLY
DROPPING SOUTHEAST ACROSS NORTHERN WISCONSIN WILL BE WORTH
MONITORING. OTHERWISE THE HIGHER PROBABILITY FOR GREATER
THUNDERSTORM COVERAGE APPEARS TO BE FOCUSED THIS EVENING AND EARLY
TONIGHT...AND WILL TARGET THIS PERIOD WITH A PROB MENTION.
FOR DTW...ONGOING THUNDERSTORM ACTIVITY WILL REMAIN IN THE VICINITY
OF THE TERMINAL THROUGH THE LATTER HALF OF THE MORNING. POTENTIAL
FOR ADDITIONAL ACTIVITY FROM LATE AFTERNOON INTO THE EARLY PART OF
TONIGHT. AT THIS STAGE...WILL GO AHEAD AN HIGHLIGHT THE MOST
FAVORED TIMEFRAME /AFTER 02Z/.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN THUNDERSTORMS THIS MORNING.
* LOW CONFIDENCE IN THUNDERSTORM POTENTIAL THIS AFTERNOON THROUGH
TONIGHT.
* MEDIUM CONFIDENCE IN CEILINGS FALLING BELOW 5000 FT WEDNESDAY
MORNING.
&&
.PREV DISCUSSION...ISSUED 347 AM EDT TUE AUG 27 2013
SHORT TERM... TODAY AND TONIGHT
LARGER SCALE ENVIRONMENT REMAINS VIRTUALLY A CARBON COPY OF THAT
NOTED 24 HOURS AGO...SE MICHIGAN RESIDING ALONG THE NORTHEAST FLANK
OF STRONG UPPER RIDGING ANCHORED OVER THE CENTRAL PLAINS.
WELL-DEFINED THETA-E/MOISTURE AXIS EMANATING SOUTHEAST OF THE MAIN
MOISTURE PLUME SITUATED OVER THE UPPER MS VALLEY NOW DRAPED ACROSS
FAR SOUTHEAST MICHIGAN. EARLY DAY FOCUS TARGETS THE INBOUND
CONVECTIVE COMPLEX CURRENTLY WORKING ACROSS NORTHERN LAKE MICHIGAN.
RECENT RADAR/SATELLITE TRENDS AND HI RES MODEL GUIDANCE SUGGEST SOME
FORM OF THIS COMPLEX WILL WORK ACROSS SE MICHIGAN THIS MORNING
/MAINLY M-59 NORTHWARD/. WHILE THE ARRAY OF MODEL GUIDANCE PROVIDE
A MIXED SIGNAL ON THE RESPONSE...THERE IS A MORE CONCERTED EXPANSION
NOTED AS THE ASSOCIATED MID LEVEL WAVE WORKS ACROSS THE EXISTING
HIGHER THETA-E PLUME. THE MORNING TIMING IS CERTAINLY NOT
IDEAL...BUT RECENT SPC MESOANALYSIS DOES REVEAL ROUGHLY 1000 J/KG OF
EXISTING MUCAPE ALONG AND SOUTHWEST OF A TRI-CITIES TO MOUNT CLEMENS
LINE. THIS WILL SUPPORT A HIGHER END POP /ESPECIALLY NORTH/...WITH
A SMALL WINDOW FOR A FEW STRONGER CELLS TO EMERGE BEFORE THE ENTIRE
COMPLEX EXITS TO THE SOUTHEAST BY LATE MORNING.
BRIEF PERIOD OF SUBSIDENCE AND SOME LAGGING RESIDENCE TIME TO THE
ASSOCIATED CIRRUS CANOPY WILL CONTAIN THE DEGREE OF DESTABILIZATION
FOR A PERIOD OF TIME INTO MIDDAY. HOWEVER...RENEWED THETA-E/WARM
AIR ADVECTION WILL COMMENCE IN THE WAKE OF THIS WAVE AS SOUTHWEST
LOW LEVEL FLOW STRENGTHENS THROUGH THE AFTERNOON AND EVENING. THIS
WILL BE SUFFICIENT FOR A SOLID LATE DAY DIURNAL RESPONSE...HIGHS
SETTLING INTO THE MIDDLE AND UPPER 80S. MUCH LIKE THIS PAST
EVENING...THIS PROCESS ALONE MAY PROVE ADEQUATE TOWARD GENERATING
WIDELY SCATTERED CONVECTION AS INSTABILITY BUILDS. A FIRM CAP WILL
REMAIN PROBLEMATIC...SO BETTER COVERAGE WOULD BE A STRUGGLE UNDER
THIS ENVIRONMENT. THERE IS SUPPORT FOR ANOTHER RIDGE CRESTING
SHORTWAVE TO ANCHOR ANOTHER ROUND OF CONVECTION ACROSS THE UPPER MS
VALLEY AT THE SAME TIME. SLIGHTLY BETTER DIURNAL DYNAMIC RESPONSE
ATTENDANT WITH THIS WAVE...WITH MAINTENANCE AND POSSIBLE UPSCALE
GROWTH EXPECTED ALONG THE MAIN INSTABILITY GRADIENT BACKED BY A
30-35 KNOT VEERING LOW LEVEL JET. 850-300 MB MEAN FLOW AND
PROJECTED CORFIDI VECTORS AGAIN PRESENT LOWER MICHIGAN IN A
FAVORABLE DOWNSTREAM POSITION...MOST FAVORED TIME TONIGHT WITHIN THE
00Z-07Z WINDOW. ORGANIZED CONVECTION BEHIND BULK SHEAR VALUES IN
EXCESS 30 KNOTS WILL BRING THE RISK OF STRONGER WIND GUSTS. A HIGH
PWAT AIRMASS WILL ALSO CONTRIBUTE TO POSSIBLE LOCALLY HEAVY
RAINFALL.
LONG TERM...WEDNESDAY THROUGH MONDAY
WEATHER OVER MICHIGAN WILL CONTINUE TO BE DOMINATED BY FLOW OVER THE
TOP OF THE LARGE UPPER RIDGE OVER THE CENTRAL PLAINS...BEFORE WE
START TO SEE SOME NORTHERN STREAM CONTRIBUTIONS OVER THE HOLIDAY
WEEKEND.
AREA OF LOW PRESSURE AND WEAK FRONT WILL CONTINUE TO DROP THROUGH
SOUTHERN LOWER MICHIGAN WEDNESDAY MORNING. GFS FORECAST SOUNDINGS
FOR DTW START TO SHOW SIGNIFICANT DRYING AND A CAP FORMING AS HIGH
PRESSURE BUILDS IN AFTER 18Z...AND WILL KEEP LOW CHANCES FOR
SHOWERS/TSTORMS ALONG/SOUTH OF M-59 ONLY THROUGH MID-DAY. MODELS
THEN REMAIN IN STRONG AGREEMENT WITH SURFACE HIGH PRESSURE BUILDING
INTO THE CENTRAL GREAT LAKES WEDNESDAY NIGHT THROUGH
THURSDAY...KEEPING THE WEATHER DRY. AIRMASS WILL REMAIN WARM EVEN
BEHIND THE FRONT WITH H850 TEMPERATURES ONLY COOLING TO 16-18 C FOR
WEDNESDAY AND THURSDAY. WITH GOOD INSOLATION THIS SHOULD KEEP
TEMPERATURES IN THE LOW AND MID 80S BOTH DAYS...SLIGHTLY COOLER
OVER THE THUMB WHERE FLOW WILL BE OFF LAKE HURON.
MODELS HAVE THEN KEYED IN ON A SHORTWAVE WITH ORIGINS OVER THE
DESERT SOUTHWEST THEN RIDING ATOP THE RIDGE AND ACROSS NORTHERN
MICHIGAN LATE THURSDAY NIGHT AND FRIDAY. THIS SETUP INITIALLY LOOKS
SLIGHTLY SIMILAR TO TODAY...A FRONT SETTLING IN OVER MICHIGAN AS
UPPER ENERGY OVER CANADA PUSHES SURFACE LOW PRESSURE TOWARDS THE
AREA. THERE ARE STILL QUITE A FEW DIFFERENCES BETWEEN THE MODELS
HOWEVER...BUT THE GENERAL IDEA IS FOR THIS INITIAL WAVE AND
POTENTIALLY A FEW OTHERS TO RIDE OVER THE FRONTAL BOUNDARY THAT WILL
BE DRAPED OVER THE REGION. THIS WILL PROVIDE A CHANCE FOR SHOWERS
AND THUNDERSTORMS FRIDAY AND SATURDAY. THE BIG DIFFERENCE BETWEEN
TODAY`S PATTERN AND THE SET-UP FOR LATER IN THE WEEK WILL BE A
FAIRLY STRONG UPPER TROUGH PUSHING THROUGH CENTRAL CANADA AND
ARRIVING INTO THE GREAT LAKES ON EITHER SATURDAY OR SUNDAY. WHILE
GFS AND EURO DIFFER WITH THE OVERALL SET-UP AND TIMING...THEY DO
AGREE WITH PUSHING A STRONG COLD FRONT DOWN ACROSS THE AREA ON
SUNDAY...PROVIDING A CONTINUATION OF CHANCES FOR SHOWERS/TSTORMS.
DRIER AIRMASS SHOULD WORK INTO THE AREA BEHIND THE FRONT...GFS
ACTUALLY HAS A SECONDARY FRONT DROPPING THROUGH ON MONDAY NOW AS
HIGH PRESSURE SETTLES DOWN INTO THE AREA. TEMPERATURES LOOK TO
REMAIN WARM WITH ABOVE NORMAL TEMPERATURES INTO THE
WEEKEND...ALTHOUGH CONVECTION COULD LIMIT HEATING AT TIMES.
TEMPERATURES SHOULD THEN COOL BEHIND THE FRONT FOR LABOR DAY...WITH
CURRENT FORECAST CARRYING MAX TEMPS ONLY IN THE 70S.
MARINE...
MOIST AND UNSTABLE ENVIRONMENT WILL SUPPORT THUNDERSTORM DEVELOPMENT
THROUGH TONIGHT. OUTSIDE OF THIS THUNDERSTORM RISK...MARINE
CONDITIONS WILL REMAIN QUITE FAVORABLE THROUGH WEDNESDAY.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......SS
AVIATION.....MR
SHORT TERM...MR
LONG TERM....HLO
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
354 AM EDT TUE AUG 27 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 418 PM EDT MON AUG 26 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE
CENTERED OVER MO/KS RESULTING IN ACYC FLOW FROM THE NRN PLAINS
THROUGH THE UPPER MS VALLEY INTO THE GREAT LAKES. WAA IN ADVANCE OF
AN UPSTREAM SHORTWAVE TROUGH MOVING INTO SW NORTH DAKOTA SUPPORTED
AN AREA OF LIGHT TO MODERATE RAIN WITH ONLY ISOLD TSRA. AT THE
SFC...THE CONVECTION THIS MORNING HELPED PUSH THE WEAK FRONTAL
BOUNDARY INTO NRN WI AND EXTENDED FROM NEAR HYR TO GRB. TEMPS TO THE
SOUTH OF THE FRONT HAVE AGAIN CLIMBED TO AROUND 90 WHILE MORE
MODERATE READINGS IN THE LOW TO MID 80S PREVAILED TO THE NORTH.
DEWPOINTS THROUGH THE REGION WERE NEAR 70F WITH 12Z OBSERVED AND
FCST SOUNDINGS SHOWING PWAT VALUES AROUND 2.0 INCHES(200 PCT OF
NORMAL).
EXPECT THAT AS THE ND SHRTWV MOVES TO THE EAST AND WAA INCREASES
THIS EVENING...EXPECT SHRA/TSRA TO DEVELOP AND QUICKLY IN INCREASE
IN COVERAGE BY LATE EVENING IN THE VCNTY OF THE SFC-800 MB FRONT
FROM CNTRL MN INTO NW WI. EVEN THOUGH THE MODELS HAVE TRENDED
FARTHER SOUTH WITH THE PCPN AND SHOW THE MOST FAVORABLE 310K
ISENTROPIC LIFT REMAINING SOUTH OF THE CWA...THERE IS STILL
CONSIDERABLE UNCERTAINTY ON THE LOCATION OF THE STRONGEST CONVECTION.
MOST OF THE HIGHER RES MODELS KEEP NEARLY ALL THE PCPN SOUTH OF
THE CWA WHILE THE GFS/ECMWF AND HIGH RES RAPID REFRESH BRING PCPN
THROUGH MAINLY THE SW HALF OF THE CWA. SO...THE HIGHER POPS/QPF WERE
SHIFTED TO THE SOUTH WITH LOCATIONS ALONG THE WI BORDER SEEING THE
GREATEST POTENTIAL FOR STRONG TSRA.
WITH MUCAPE VALUES INTO THE 1000-1500 J/KG RANGE AND EFFECTIVE SHEAR
TO AROUND 30 KT...THERE IS THE POTENTIAL FOR MULTICELL CLUSTERS THAT
COULD PRODUCE VERY HEAVY RAIN AND LCL WIND DAMAGE...SIMILAR TO LAST
NIGHT. FCST CORFIDI VECTORS SUGGEST THAT STORM ELEMENTS SHOULD KEEP
ENOUGH FORWARD MOTION TO LIMIT POTENTIAL FOR EXCESSIVE RAINFALL.
HOWEVER...ONE TO TWO INCHES AMOUNTS MAY AGAIN BE COMMON ALONG THE
PATH OF HEAVIER CLUSTERS. ANY LEFTOVER SHRA/TSRA TUE MORNING OVER
MAINLY THE S CNTRL CWA IS EXPECTED TO DIMINISH AND SAG OFF TO THE SE
BY EARLY TO MID AFTERNOON.
WITH 850 MB TEMPS REMAINING AROUND 18C...MAX TEMPS SHOULD ALSO BE
SIMILAR TO TODAY WITH HIGHS INTO THE LOW TO MID 80S WITH SLIGHTLY
COOLER READINGS ALONG THE GREAT LAKES.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 354 AM EDT TUE AUG 27 2013
WEDNESDAY CONTINUES TO LOOK LIKE A BREAK FROM THE PERIOD OF ACTIVE
WEATHER THAT HAS BEEN AFFECTING THE UPPER GREAT LAKES REGION. THIS
IS DUE TO THE MAIN SHORTWAVE ROUNDING THE UPPER RIDGE MOVING THROUGH
EASTERN ONTARIO AND A HIGH PRESSURE RIDGE NOSING SOUTH OVER THE AREA
FROM A HIGH OVER HUDSON BAY. THIS HIGH WILL INFLUENCE OUR WEATHER
INTO WEDNESDAY NIGHT.
SINCE THE HIGH IS PROVIDING PLENTY OF DRY AIR ALOFT...THE FORECAST
COMES DOWN TO THE NEAR SURFACE FEATURES. IN THIS CASE...THE LOW
LEVEL WINDS HAVE A LARGE AFFECT ON THE WEATHER FOR WEDNESDAY
MORNING...AS THE LIGHT NORTHERLY FLOW WILL LIKELY PUSH FOG OVER THE
AREA FROM LAKE SUPERIOR. THERE WAS A DECENT AMOUNT OF FOG OVER
EASTERN LAKE SUPERIOR THIS PAST EVENING...SO AS LONG AS THAT
CONTINUES TODAY...WOULD EXPECT IT TO BE AFFECTING THE AREA TONIGHT
INTO WEDNESDAY MORNING. THE WINDS ARE FAIRLY LIGHT DURING THAT
PERIOD...SO THAT MAY LIMIT THE INLAND EXTENT ALTHOUGH CLEARING
SKIES TONIGHT WILL AID IN DEVELOPMENT FOR INLAND LOCATIONS. WILL
CONTINUE THE IDEA STARTED SEVERAL DAYS AGO FOR THE FOG ON WEDNESDAY
MORNING...WITH THE THICKEST FOG NEAR LAKE SUPERIOR...THE HIGHER
TERRAIN OF THE NORTH CENTRAL AND KEWEENAW...ALONG WITH THE EAST
WHERE THE FOG IS CURRENTLY THE THICKEST. ONCE DIURNAL HEATING TAKES
HOLD...WOULD EXPECT THE FOG TO DIMINISH AND MIX OUT THROUGH THE
MORNING WITH ONLY A FEW LOW BASED STRATOCU REMAINING TOWARDS EARLY
AFTERNOON. WILL CONTINUE THAT IDEA FOR THE SKY GRIDS ON WEDNESDAY.
OTHERWISE...WITH THE INCREASING SUNSHINE...SHOULD BE ANOTHER ABOVE
NORMAL DAY ACROSS THE AREA. HIGHS WILL RANGE FROM MID 70S NEAR LAKE
SUPERIOR TO MID 80S TOWARDS THE WISCONSIN BORDER WHERE THERE WILL BE
GREATER SUNSHINE.
WEDNESDAY NIGHT SHOULD BE DRY BUT THE NEXT SHORTWAVE WILL
APPROACHING THE AREA FROM NORTH DAKOTA ON THURSDAY. DID LINGER THE
FOG OVER LAKE SUPERIOR INTO WEDNESDAY NIGHT SINCE THE NORTHERLY FLOW
IS FAIRLY LIGHT AND THE EXPECTED DEWPOINTS UPSTREAM ARE IN THE LOW
60S. THIS WON/T BE THAT MUCH DRIER AND THE LIMITED MIXING MAY KEEP
FOG AROUND. IF THAT OCCURS...IT MAY HOLD ON INTO THURSDAY OR BEYOND
DUE TO THE LIGHT WINDS.
DEFINITELY SEEMS LIKE BETTER AGREEMENT IN GFS/ECMWF ON THE TRACK OF
THE SHORTWAVE ACROSS UPPER MICHIGAN AND NORTHERN WISCONSIN THURSDAY
AFTERNOON INTO THURSDAY NIGHT. LIKE TONIGHT...BEST 850-700MB
WAA/MOISTURE TRANSPORT IS FOCUSED JUST TO THE SOUTHWEST OF OUR
CWA. THAT LINES UP WELL WITH THE LOCATION OF THE BEST INSTABILITY
(1000-1500 J/KG OF MUCAPE IN NORTHERN WISCONSIN) AND LOW LEVEL JET.
THUS...WOULD THINK WE WILL BE ON THE NORTHERN SIDE OF THE BEST
PRECIPITATION AND WILL RUN CHANCE POPS OVER THE SOUTHWEST HALF OF
THE CWA THURSDAY NIGHT INTO FRIDAY MORNING.
THIS SHORTWAVE WILL DEPART AND PUT THE AREA UNDER ANOTHER WEAK
CANADIAN HIGH PRESSURE RIDGE FOR FRIDAY AFTERNOON INTO FRIDAY
NIGHT. MODELS DIFFER GREATLY FOR THE LABOR DAY WEEKEND ON HOW TO
HANDLE THE NEXT COUPLE OF WAVES EXITING THE TROUGH OFF THE PACIFIC
NORTHWEST AND THE BROAD LOW PRESSURE SYSTEM MOVING ACROSS THE AREA.
THERE HAS BEEN A TREND OVER THE LAST DAY OF HEADING TOWARDS MORE
NORMAL TEMPERATURES WITH THE BREAK DOWN OF THE NORTHERN SIDE OF THE
UPPER RIDGE. WILL START TRENDING TEMPERATURES DOWN...BUT NOT AS LOW
AS THE 26-12Z ECMWF WHICH HAD HIGHS IN THE 60S FOR SUNDAY AND
MONDAY. LATE ARRIVING 00Z ECMWF IS EVEN COLDER WITH 0C 850MB TEMPS
OVER THE KEWEENAW AT 00Z MONDAY AND MUCH OF THE CWA AT 12Z. THIS
WOULD END UP GIVING HIGHS IN THE 50S AND THE POTENTIAL FOR LAKE
ENHANCED CLOUDS ON MONDAY WITH A STRONG UPPER TROUGH MOVING THROUGH.
DEFINITELY SOMETHING TO WATCH OVER THE COMING DAYS. WITH THE WIDE
SPREAD ON TIMING/LOCATION OF PRECIPITATION FOR THE WEEKEND...WILL
JUST CONTINUE A CONSENSUS OF THE MODELS WITH SLIGHT AND LOW CHANCE
POPS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 354 AM EDT TUE AUG 27 2013
SHRA/TSRA WILL IMPACT THE REGION OVERNIGHT AT IWD AND AT SAW WITH
POSSIBLE MVFR CONDITIONS. CMX SHOULD REMAIN DRY OVERNIGHT. VFR
CONDITIONS EXPECTED FOR ALL TAF SITES ON TUE AND TUE NIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 354 AM EDT TUE AUG 27 2013
LIMITED PRESSURE GRADIENTS ACROSS LAKE SUPERIOR SHOULD KEEP WINDS
BELOW 20KTS THROUGH THE FORECAST PERIOD. FOG EXPANDED ACROSS EASTERN
LAKE SUPERIOR YESTERDAY AND WOULD EXPECT IT TO SPREAD WEST ACROSS
THE REST OF THE LAKE TODAY WITH HIGH DEWPOINTS AND THE SHOWERS THAT
ARE MOVING THROUGH. AS WINDS TURN TO THE NORTH TONIGHT...EXPECT THE
FOG TO PUSH SOUTH THROUGH WEDNESDAY MORNING AND THEN DIMINISH SOME
AS SLIGHTLY DRIER CANADIAN AIR MOVES SOUTH OVER THE LAKE THROUGH
WEDNESDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1245 PM CDT TUE AUG 27 2013
.AVIATION...18Z TAF ISSUANCE...
LOW CLOUDS CONTINUE TO ERODE ACROSS THE SRN TERMINALS...FROM BRD
TO HYR THIS MORNING...AND SHOULD BECOME VFR BY 19/20Z. WILL SEE
SCATTERED CONVECTIVE CU FIELD THIS AFTERNOON...EVENTUALLY
DISSIPATE BY THE EVENING AND FOG/LOW CLOUDS DEVELOP AROUND OR JUST
AFTER MIDNIGHT. WITH LIGHT WINDS AND MOSTLY CLEAR SKIES ALL
AROUND...FOG EXPECTED AT ALL FCST TERMINALS...WITH LIFR VSBYS AND
CIGS THROUGH 12/14Z.
&&
.PREV DISCUSSION... /ISSUED 1054 AM CDT TUE AUG 27 2013/
UPDATE...
AT 1045AM/1545Z...THERE WAS A FRONT STRETCHING FROM WEST TO EAST
JUST SOUTH OF THE FORECAST AREA. THE SOUTHERN FORECAST AREA HAD
CLOUDY SKIES...WHILE THE NORTHERN HALF WAS SUNNY. THERE WAS LITTLE
IF ANY WIND ACROSS THE NORTHLAND. TEMPERATURES WERE IN THE 70S.
I UPDATED THE FORECAST THROUGH THIS EVENING...FOCUSING ON CLOUD
COVER AND THE CHANCES OF SHOWERS AND STORMS. BASED ON THE LATEST
MODELS...ESPECIALLY THE HRRR AND RAP13 MODELS...I BELIEVE THERE
ARE EVEN LOWER CHANCES OF SHOWERS AND STORMS ACROSS THE SOUTHERN
AND SOUTHEASTERN FORECAST AREA THAN PREVIOUSLY FORECASTED. I
LOWERED THE CHANCES OF PCPN...AND MOSTLY CONFINED THE CHANCES
THROUGH THE AFTERNOON TO NW WISCONSIN. IF ANY STORMS DO
DEVELOP...THERE COULD BE A FEW STRONG STORMS WITH SMALL HAIL.
THE CLOUD COVER ACROSS THE SOUTHERN FORECAST AREA IS MOSTLY
REMNANTS FROM MORNING FOG. IT SHOULD CONTINUE TO LIFT AND BREAK
APART THROUGH EARLY THIS AFTERNOON. OTHERWISE...THE NORTHLAND CAN
EXPECT MOSTLY TO PARTLY SUNNY SKIES BY MID AFTERNOON.
TEMPERATURES SHOULD STILL BE QUITE HOT TODAY WITH HIGHS MOSTLY IN
THE UPPER 80S AND LOW 90S EXCEPT CLOSER TO LAKE SUPERIOR. HEAT
INDICES WILL BE AROUND 95 DEGREES ACROSS THE FAR SOUTHERN FORECAST
AREA FOR A BRIEF TIME DURING THE MID TO LATE AFTERNOON.
PREV DISCUSSION... /ISSUED 644 AM CDT TUE AUG 27 2013/
AVIATION...12Z TAF ISSUANCE...
WIDESPREAD LOW STRATUS WITH BR/FG THIS MORNING AS UNUSUALLY MOIST
AIR REACHES SATURATION AT SFC. EXPECT IMPROVEMENT AT MOST SITES BY
14Z TO 15Z AS SUNSHINE WORKS ON EVAPORATION OF LOW STRATUS LAYER.
OTHERWISE VFR THROUGH THE DAY ALTHOUGH SPOTTY CONVECTION MAY
REDEVELOP NEAR KDLH/KHYR/KBRD TERMINALS. EXPECT FOG/BR TO
REDEVELOP THIS EVENING AND MAY NEED TO LOWER VIS/CIGS IN NEXT TAF
FCST.
PREV DISCUSSION... /ISSUED 335 AM CDT TUE AUG 27 2013/
SHORT TERM...THROUGH EARLY WEDNESDAY AFTERNOON.
A FRONTAL BOUNDARY WAS DRAPED ACROSS THE REGION THIS
MORNING...FROM SOUTH DAKOTA ACROSS CENTRAL MINNESOTA INTO NORTHERN
WISCONSIN. THIS FEATURE HAS BEEN THE FOCUS FOR CONTINUED
THUNDERSTORMS OVERNIGHT...ALTHOUGH THERE FINALLY DOES SEEM TO BE A
BACK EDGE. LITTLE WAS OCCURRING ACROSS AITKIN/ITASCA
COUNTIES...WITH MOST OF THE STORMS OVER FAR NORTHERN WISCONSIN
BACK INTO THE TWIN PORTS/MOOSE LAKE AREAS. A LARGE AREA OF PWAT
VALUES AROUND 2 INCHES WAS OVER THE AREA WITH FGEN AIDING IN
FORCING. WE EXPECT ADDITIONAL SHOWERS AND STORMS TO FORM OVERNIGHT
INTO THIS MORNING. THE AREA OF STORMS WAS SINKING SOUTHWARD
SOME...SO WE WILL CONTINUE THE FLASH FLOOD WATCH FOR A COUPLE MORE
HOURS AT LEAST. AREAS OVER FAR NORTHERN WISCONSIN CONTINUE TO GET
RAIN...HEAVY IN SPOTS. THE HEAVIEST RAIN TONIGHT SO FAR APPEARS TO
BE OVER THE SANDIER SOILS OF BAYFIELD/DOUGLAS COUNTIES. WE`LL HAVE
TO MONITOR THOUGH...AND MAY NEED TO ISSUE A FLOOD ADVISORY. THERE
IS STILL A SMALL SEVERE THREAT THIS MORNING...MAINLY OVER
NORTHWEST WISCONSIN...WITH DAMAGING WINDS BEING THE MAIN THREAT. A
SMALL SEVERE THREAT WILL LINGER OVER OUR EASTERN WISCONSIN ZONES
INTO THE AFTERNOON AS WELL.
THIS AFTERNOON...THE LOW WILL MOVE EAST AND SOUTH OF THE CWA. IT
WILL REMAIN VERY WARM AND HUMID THOUGH WITH TEMPERATURES IN THE
UPPER EIGHTIES TO LOWER NINETIES. AN ONSHORE WIND OR RAIN WILL
KEEP AREAS AROUND LAKE SUPERIOR INCLUDING THE SOUTH SHORE COOLER.
WE DID NOT ISSUE ANY HEAT ADVISORIES TODAY...AS HEAT INDICES WILL
MAINLY BE IN THE LOWER TO MIDDLE NINETIES.
WE EXPECT IT TO BE DRY TONIGHT WITH SOME FOG POSSIBLE.
WE ALSO KEPT IT DRY ON WEDNESDAY WITH WEAK HIGH PRESSURE IN
CONTROL. IT WILL BE WARM...WITH HIGHS IN THE UPPER EIGHTIES TO
LOWER NINETIES. IT WILL AGAIN BE COOLER AROUND LAKE SUPERIOR.
EXTENDED FORECAST...WEDNESDAY NIGHT THROUGH TUESDAY...
CWA WILL REMAIN UNDERNEATH THE SRN EDGE OF THE WESTERLIES THROUGH
THE WEEK BEFORE CHANGES ARE ADVERTISED BY MED RANGE NWP. ECMWF WAS
OUTLIER YESTERDAY IN ITS AMPLIFICATION OF THE UPPER TROF OVER AND
EAST OF THE REGION THIS WEEKEND. THE GFS/GEM ARE NOW TRENDING IN
THAT DIRECTION AS WELL. CONFIDENCE IS INCREASING THAT AFTER THE
HEAT/HUMIDITY THIS WEEK A RETURN TO CLIMO AND PERHAPS BLO CLIMO
CONDITIONS WILL OCCUR LATE THIS WEEKEND AND EARLY NEXT WEEK.
UNTIL THEN ANOTHER ROUND OF CONVECTIVE ACTIVITY SHOULD OCCUR
THUR/FRIDAY AS A SHORTWAVE TROF TRAVERSES THE NRN FRINGE OF THE
UPPER RIDGE. AS USUAL THE TIMING OF THE SPECIFICS RELATED TO AN
MCC/MCS DEVELOPMENT ARE NOT A HIGH CONFIDENCE ENDEAVOR AT THIS
POINT. THE INITIAL ESTIMATE IS THAT A WARM ADVECTION REGIME WILL
INCREASE INSTABILITY THURSDAY. GEM/GFS/EC POSITION GREATEST PERIOD
OF 85H MSTR TRANSPORT OVER CWA BETWEEN 18Z THUR-06Z FRIDAY.
CONVECTION SHOULD MOVE EAST OF THE CWA FRIDAY WITH DECREASING POPS
WEST TO EAST. AT THIS POINT THE UPPER FLOW BEGINS TO SHIFT TO UPPER
RIDING OVER THE WRN CONUS AND TROUGHING OVER THE ERN GTLKS. TO
ASSIST THIS TRANSFORMATION...A MIGRATORY SHORTWAVE WILL DESCEND
ACROSS THE REGION AMIDST DEEPENING UPPER TROUGH AND SWING A FAIRLY
STRONG COLD FRONT ACROSS THE CWA SATURDAY NIGHT. FCST MAX TEMPS
SATURDAY MAY NEED SIGNIFICANT ADJUSTMENT DUE TO POTENTIAL OF
PREFRONTAL COMPRESSION AND ADVECTION OF SIGNIFICANT LOW LVL THERMAL
RIDGE AHEAD OF STRONG FRONT. EC FCST 85H TEMPS DROP FROM 18C TO 2C
OVER NRN MN ZONES FROM 0Z SUN TO 0Z MON. GEM/GFS ARE MUCH LESS
AGGRESSIVE IN MAGNITUDE BUT DO LOWER TEMPS SUBSTANTIALLY. SHOULD SEE
A POTENTIAL FOR CONVECTION AHEAD OF FRONT SATURDAY EVENING. MAY BE
BLUSTERY BEHIND FRONT SUNDAY BASED ON FCST KINEMATICS AND MECHANICAL
MIXING IN BDRY LYR SUNDAY AFTERNOON. PLEASANT WX APPEARS MORE
PROBABLE WE HEAD INTO THE NEW WEEK.
&&
.POINT TEMPS/POPS...
DLH 63 86 65 80 / 10 0 10 40
INL 58 87 64 79 / 0 0 20 50
BRD 65 91 68 86 / 0 0 30 50
HYR 62 90 65 82 / 10 0 10 30
ASX 62 83 62 79 / 10 0 10 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS DULUTH MN
1054 AM CDT TUE AUG 27 2013
.UPDATE...
AT 1045AM/1545Z...THERE WAS A FRONT STRETCHING FROM WEST TO EAST
JUST SOUTH OF THE FORECAST AREA. THE SOUTHERN FORECAST AREA HAD
CLOUDY SKIES...WHILE THE NORTHERN HALF WAS SUNNY. THERE WAS LITTLE
IF ANY WIND ACROSS THE NORTHLAND. TEMPERATURES WERE IN THE 70S.
I UPDATED THE FORECAST THROUGH THIS EVENING...FOCUSING ON CLOUD
COVER AND THE CHANCES OF SHOWERS AND STORMS. BASED ON THE LATEST
MODELS...ESPECIALLY THE HRRR AND RAP13 MODELS...I BELIEVE THERE
ARE EVEN LOWER CHANCES OF SHOWERS AND STORMS ACROSS THE SOUTHERN
AND SOUTHEASTERN FORECAST AREA THAN PREVIOUSLY FORECASTED. I
LOWERED THE CHANCES OF PCPN...AND MOSTLY CONFINED THE CHANCES
THROUGH THE AFTERNOON TO NW WISCONSIN. IF ANY STORMS DO
DEVELOP...THERE COULD BE A FEW STRONG STORMS WITH SMALL HAIL.
THE CLOUD COVER ACROSS THE SOUTHERN FORECAST AREA IS MOSTLY
REMNANTS FROM MORNING FOG. IT SHOULD CONTINUE TO LIFT AND BREAK
APART THROUGH EARLY THIS AFTERNOON. OTHERWISE...THE NORTHLAND CAN
EXPECT MOSTLY TO PARTLY SUNNY SKIES BY MID AFTERNOON.
TEMPERATURES SHOULD STILL BE QUITE HOT TODAY WITH HIGHS MOSTLY IN
THE UPPER 80S AND LOW 90S EXCEPT CLOSER TO LAKE SUPERIOR. HEAT
INDICES WILL BE AROUND 95 DEGREES ACROSS THE FAR SOUTHERN FORECAST
AREA FOR A BRIEF TIME DURING THE MID TO LATE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 644 AM CDT TUE AUG 27 2013/
AVIATION...12Z TAF ISSUANCE...
WIDESPREAD LOW STRATUS WITH BR/FG THIS MORNING AS UNUSUALLY MOIST
AIR REACHES SATURATION AT SFC. EXPECT IMPROVEMENT AT MOST SITES BY
14Z TO 15Z AS SUNSHINE WORKS ON EVAPORATION OF LOW STRATUS LAYER.
OTHERWISE VFR THROUGH THE DAY ALTHOUGH SPOTTY CONVECTION MAY
REDEVELOP NEAR KDLH/KHYR/KBRD TERMINALS. EXPECT FOG/BR TO
REDEVELOP THIS EVENING AND MAY NEED TO LOWER VIS/CIGS IN NEXT TAF
FCST.
PREV DISCUSSION... /ISSUED 335 AM CDT TUE AUG 27 2013/
SHORT TERM...THROUGH EARLY WEDNESDAY AFTERNOON.
A FRONTAL BOUNDARY WAS DRAPED ACROSS THE REGION THIS
MORNING...FROM SOUTH DAKOTA ACROSS CENTRAL MINNESOTA INTO NORTHERN
WISCONSIN. THIS FEATURE HAS BEEN THE FOCUS FOR CONTINUED
THUNDERSTORMS OVERNIGHT...ALTHOUGH THERE FINALLY DOES SEEM TO BE A
BACK EDGE. LITTLE WAS OCCURRING ACROSS AITKIN/ITASCA
COUNTIES...WITH MOST OF THE STORMS OVER FAR NORTHERN WISCONSIN
BACK INTO THE TWIN PORTS/MOOSE LAKE AREAS. A LARGE AREA OF PWAT
VALUES AROUND 2 INCHES WAS OVER THE AREA WITH FGEN AIDING IN
FORCING. WE EXPECT ADDITIONAL SHOWERS AND STORMS TO FORM OVERNIGHT
INTO THIS MORNING. THE AREA OF STORMS WAS SINKING SOUTHWARD
SOME...SO WE WILL CONTINUE THE FLASH FLOOD WATCH FOR A COUPLE MORE
HOURS AT LEAST. AREAS OVER FAR NORTHERN WISCONSIN CONTINUE TO GET
RAIN...HEAVY IN SPOTS. THE HEAVIEST RAIN TONIGHT SO FAR APPEARS TO
BE OVER THE SANDIER SOILS OF BAYFIELD/DOUGLAS COUNTIES. WE`LL HAVE
TO MONITOR THOUGH...AND MAY NEED TO ISSUE A FLOOD ADVISORY. THERE
IS STILL A SMALL SEVERE THREAT THIS MORNING...MAINLY OVER
NORTHWEST WISCONSIN...WITH DAMAGING WINDS BEING THE MAIN THREAT. A
SMALL SEVERE THREAT WILL LINGER OVER OUR EASTERN WISCONSIN ZONES
INTO THE AFTERNOON AS WELL.
THIS AFTERNOON...THE LOW WILL MOVE EAST AND SOUTH OF THE CWA. IT
WILL REMAIN VERY WARM AND HUMID THOUGH WITH TEMPERATURES IN THE
UPPER EIGHTIES TO LOWER NINETIES. AN ONSHORE WIND OR RAIN WILL
KEEP AREAS AROUND LAKE SUPERIOR INCLUDING THE SOUTH SHORE COOLER.
WE DID NOT ISSUE ANY HEAT ADVISORIES TODAY...AS HEAT INDICES WILL
MAINLY BE IN THE LOWER TO MIDDLE NINETIES.
WE EXPECT IT TO BE DRY TONIGHT WITH SOME FOG POSSIBLE.
WE ALSO KEPT IT DRY ON WEDNESDAY WITH WEAK HIGH PRESSURE IN
CONTROL. IT WILL BE WARM...WITH HIGHS IN THE UPPER EIGHTIES TO
LOWER NINETIES. IT WILL AGAIN BE COOLER AROUND LAKE SUPERIOR.
EXTENDED FORECAST...WEDNESDAY NIGHT THROUGH TUESDAY...
CWA WILL REMAIN UNDERNEATH THE SRN EDGE OF THE WESTERLIES THROUGH
THE WEEK BEFORE CHANGES ARE ADVERTISED BY MED RANGE NWP. ECMWF WAS
OUTLIER YESTERDAY IN ITS AMPLIFICATION OF THE UPPER TROF OVER AND
EAST OF THE REGION THIS WEEKEND. THE GFS/GEM ARE NOW TRENDING IN
THAT DIRECTION AS WELL. CONFIDENCE IS INCREASING THAT AFTER THE
HEAT/HUMIDITY THIS WEEK A RETURN TO CLIMO AND PERHAPS BLO CLIMO
CONDITIONS WILL OCCUR LATE THIS WEEKEND AND EARLY NEXT WEEK.
UNTIL THEN ANOTHER ROUND OF CONVECTIVE ACTIVITY SHOULD OCCUR
THUR/FRIDAY AS A SHORTWAVE TROF TRAVERSES THE NRN FRINGE OF THE
UPPER RIDGE. AS USUAL THE TIMING OF THE SPECIFICS RELATED TO AN
MCC/MCS DEVELOPMENT ARE NOT A HIGH CONFIDENCE ENDEAVOR AT THIS
POINT. THE INITIAL ESTIMATE IS THAT A WARM ADVECTION REGIME WILL
INCREASE INSTABILITY THURSDAY. GEM/GFS/EC POSITION GREATEST PERIOD
OF 85H MSTR TRANSPORT OVER CWA BETWEEN 18Z THUR-06Z FRIDAY.
CONVECTION SHOULD MOVE EAST OF THE CWA FRIDAY WITH DECREASING POPS
WEST TO EAST. AT THIS POINT THE UPPER FLOW BEGINS TO SHIFT TO UPPER
RIDING OVER THE WRN CONUS AND TROUGHING OVER THE ERN GTLKS. TO
ASSIST THIS TRANSFORMATION...A MIGRATORY SHORTWAVE WILL DESCEND
ACROSS THE REGION AMIDST DEEPENING UPPER TROUGH AND SWING A FAIRLY
STRONG COLD FRONT ACROSS THE CWA SATURDAY NIGHT. FCST MAX TEMPS
SATURDAY MAY NEED SIGNIFICANT ADJUSTMENT DUE TO POTENTIAL OF
PREFRONTAL COMPRESSION AND ADVECTION OF SIGNIFICANT LOW LVL THERMAL
RIDGE AHEAD OF STRONG FRONT. EC FCST 85H TEMPS DROP FROM 18C TO 2C
OVER NRN MN ZONES FROM 0Z SUN TO 0Z MON. GEM/GFS ARE MUCH LESS
AGGRESSIVE IN MAGNITUDE BUT DO LOWER TEMPS SUBSTANTIALLY. SHOULD SEE
A POTENTIAL FOR CONVECTION AHEAD OF FRONT SATURDAY EVENING. MAY BE
BLUSTERY BEHIND FRONT SUNDAY BASED ON FCST KINEMATICS AND MECHANICAL
MIXING IN BDRY LYR SUNDAY AFTERNOON. PLEASANT WX APPEARS MORE
PROBABLE WE HEAD INTO THE NEW WEEK.
&&
.POINT TEMPS/POPS...
DLH 82 63 86 65 / 10 10 0 10
INL 86 58 87 64 / 0 0 0 20
BRD 92 65 91 68 / 10 0 0 30
HYR 87 62 90 65 / 30 10 0 10
ASX 79 62 83 62 / 20 10 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...GROCHOCINSKI
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
805 PM MDT WED AUG 28 2013
.UPDATE...
WILL CANCEL FLASH FLOOD WATCH EARLY BASED ON LATEST RADAR RETURNS.
ADJUSTED POPS DOWN SOME OVER W AND CNTRL AREAS ACCORDINGLY. FFA
AND ZFP OUT SHORTLY. CHJ
&&
.PREV DISCUSSION...545 PM MDT WED AUG 28 2013...
.AVIATION...
00Z TAF CYCLE
AREA OF STRATIFORM PRECIPITATION CONTINUES TO MOVE NNW ACROSS SRN
NM THIS AFTN. LATEST HI-RES MODEL SHOWS SOME OF THIS PRECIP MOVING
UP THE RIO GRANDE VALLEY INTO ABQ LATE TONIGHT AND HAVE INSERTED A
VCSH INTO ABQ BY 12Z...THOUGH IT MAY BE SOONER. CONFIDENCE IN THIS
OCCURRING IS MODERATE ATTM. MT TOPS MAY BE OBSCURED ACROSS THE SW
AND SC MTNS AT TIMES OVERNIGHT. OTHERWISE...ISOLD TS ACROSS THE
NORTHERN MTNS WILL LIKELY DIMINISH BY 03-04Z AGAIN THIS EVE.
INSTABILITY AND THEREFORE TS POTENTIAL IS UNCERTAIN FOR THURS. IF
MID AND HIGH LEVEL CLOUDS LINGER FROM OVERNIGHT SHOWERS...IT MAY
BE TOO STABLE FOR MUCH TS. REGARDLESS...AREAS SW OF A LINE FROM
KGUP TO KSRR WILL HAVE THE BEST CHANCE FOR PRECIP AFT 15Z. 34
.PREV DISCUSSION...255 PM MDT WED AUG 28 2013...
A DEEP SUBTROPICAL MOISTURE SURGE HAS ARRIVED OVER SOUTHERN NM AS A
WELL DEFINED INVERTED TROUGH SHIFTS SLOWLY NORTHWEST OF THE AREA.
CIRA BLENDED TOTAL PWAT VALUES ARE 150-175PCT OF NORMAL OVER THE
EL PASO AREA...AND THIS MOISTURE WILL ADVECT NORTH THRU TONIGHT ON
INCREASING 700-500MB SSE FLOW. ABUNDANT CLOUD COVER HAS LIMITED
CONVECTION ACROSS MUCH OF THE SOUTH THUS FAR HOWEVER A SLUG OF
NMRS SHRA/TSRA DEVELOPING AROUND I-10 AND IS SLIDING NORTH. LATEST
RUC AND HRRR SHOW THIS MASS OF PRECIP MOVING NORTH UP THE RGV AND
SOUTHERN HIGH TERRAIN INTO THIS EVENING BEFORE TAPERING OFF AFTER
MIDNIGHT. HAVE TIGHTENED UP POPS FURTHER WITH FOCUS OVER CATRON...
SOCORRO...AND LINCOLN COUNTIES.
CLOUD COVER ASSCD WITH THIS AREA OF PRECIP WILL LINGER INTO EARLY
THURSDAY AND LIKELY LIMIT CONVECTION AGAIN UNTIL LATE DAY WITHIN
ITS PERIPHERY. MODELS DO SHOW A SIMILAR FEATURE TMRW BUT FARTHER
NORTH WITH A MASS OF SHRA/TSRA SLIDING ACROSS THE SW HIGH TERRAIN
AND SOUTHERN PORTIONS OF THE NM CONT DVD THRU MID DAY. CONVECTION
SHOULD BE MORE WIDESPREAD FOR THE REMAINDER OF THE HIGH TERRAIN
AFT 3 OR 4 PM AS THETA-E RIDGE VALUES ARE HIGHER AND LIFTED INDICES
MORE UNSTABLE.
THE REAL JUICE AND FORCING MOVES INTO THE REGION FRIDAY THRU MONDAY
WITH PWAT VALUES AVERAGING AROUND 1.2 INCHES. FOCUS FOR CONVECTION
WILL BE OVER NORTHERN AND WESTERN NM FRIDAY...THEN OVER CENTRAL
AND NORTHERN NM FOR SATURDAY THROUGH MONDAY AS A BACK DOOR FRONTAL
BNDRY MOVES SW OVER THE AREA. LCL HEAVY RAIN THREAT WILL INCREASE
AND FLASH FLOOD WATCHES ARE POSSIBLE FOR AT LEAST BURN SCAR AREAS
THRU THE LABOR DAY HOLIDAY. FOLKS PLANNING OUTDOOR ACTIVITIES OVER
THE HOLIDAY WEEKEND SHOULD PREPARE FOR WET WEATHER. TEMPS IN THIS
PATTERN WILL BE CLOSER TO SEASONAL NORMALS. GUYER
.FIRE WEATHER...
BASED ON SATELLITE IMAGERY...ABUNDANT MOISTURE IS TRYING TO FLOW UP
FROM MEXICO. SOUTHERN PORTIONS OF THE AREA...ESPECIALLY SOCORRO
COUNTY WESTWARD WILL EXPERIENCE WETTING RAIN TODAY AND TONIGHT.
ISOLATED WETTING RAIN WILL BE FOUND FURTHER NORTH OVER THE NORTHWEST
AND NORTH CENTRAL MOUNTAINS. THE MID LEVEL DRY INTRUSION WHICH WAS
SQUARELY OVER THE FORECAST AREA YESTERDAY HAS SHIFTED
NORTH/NORTHEAST...THUS THE LOWEST HUMIDITY VALUES ARE FOUND THERE.
OVERALL...HUMIDITY VALUES HAVE TRENDED UP TODAY.
MOISTURE WILL CONTINUE TO MOVE NORTH AND WESTWARD ON THURSDAY. THIS
WILL SET THE STAGE FOR INCREASE WETTING RAIN COVERAGE CENTRAL
MOUNTAINS WESTWARD DURING THE AFTERNOON AND EVENING. A PRETTY DECENT
WETTING RAIN SIGNAL SHOWS UP ACROSS THE NORTHWEST AND WEST CENTRAL
HIGHLANDS. DRIER AND MORE STABLE AIR WILL BE FOUND OVER THE EASTERN
PLAINS. HUMIDITY VALUES FOR THE MOST PART WILL TREND UP EVEN MORE
ALTHOUGH LOWER SLIGHTLY ACROSS THE FAR EAST. HIGH TEMPERATURES WILL
BE ABOVE NORMAL NORTH AND EAST AS THE HIGH CENTER SHIFTS MORE OVER
PORTIONS OF THE SOUTHERN ROCKIES AND PLAINS INCLUDING OVER PARTS OF
NEW MEXICO. DUE TO THE PROXIMITY OF THE HIGH PRESSURE
ALOFT...VENTILATION RATES WILL LOWER ACROSS MOST OF THE AREA.
THE WEATHER MODELS DEPICT A BROAD HIGH PRESSURE AREA OVER THE DESERT
SOUTHWEST AND SOUTHERN ROCKIES FRIDAY INTO SATURDAY. SMALLER
ATMOSPHERIC WAVES WILL ROTATE AROUND THIS HIGH PRESSURE AREA AND
KICK OFF SCATTERED TO NUMEROUS WETTING THUNDERSTORMS. WESTERN AND
NORTHERN PORTIONS OF NM WILL MOST LIKELY EXPERIENCE THESE WAVES.
DRIER AND MORE STABLE AIR ALOFT WILL REMAINED CENTERED OVER EASTERN
NM. THE FLOW ALOFT WILL BE RATHER WEAK DURING THIS PERIOD SO SOME
POOR VENTILATION RATES SHOW UP IN AREAS. HIGH TEMPERATURES WILL
GENERALLY BE NEAR NORMAL WEST AND SEVERAL DEGREES ABOVE NORMAL EAST.
MINIMUM HUMIDITY VALUES WILL ALSO BE IN THE 20S EAST AND CANT RULE
OUT SOME UPPER TEENS. THUS CURING OF THE FINE OR GRASS FUELS WOULD MOST
LIKELY CONTINUE THERE.
BOTH THE GFS AND ECMWF MODELS SHOW AN UPTICK IN WETTING
THUNDERSTORMS OVER THE ENTIRE FORECAST AREA SUNDAY INTO EARLY NEXT
WEEK. THE UPPER HIGH WEAKENS SOME AND ALLOWS THE ATMOSPHERE TO
BECOME MORE UNSTABLE. ABUNDANT LOW LEVEL MOISTURE WOULD ALSO BEGIN
TO FILL IN ACROSS THE FORECAST AREA AND ALLOW FOR SCATTERED TO
NUMEROUS WETTING STORMS. THIS PERIOD COULD BECOME SOME SORT OF PSEUDO
MONSOON BURST EVENT. WILL CONTINUE TO MONITOR THE MODELS AND GET A
BETTER GAUGE FOR CONFIDENCE AS TIME GOES ON. CONDITIONS WOULD THEN
GRADUALLY IMPROVE SOME ACROSS THE EASTERN PLAINS. 50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
40
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
545 PM MDT WED AUG 28 2013
.AVIATION...
00Z TAF CYCLE
AREA OF STRATIFORM PRECIPITATION CONTINUES TO MOVE NNW ACROSS SRN
NM THIS AFTN. LATEST HI-RES MODEL SHOWS SOME OF THIS PRECIP MOVING
UP THE RIO GRANDE VALLEY INTO ABQ LATE TONIGHT AND HAVE INSERTED A
VCSH INTO ABQ BY 12Z...THOUGH IT MAY BE SOONER. CONFIDENCE IN THIS
OCCURRING IS MODERATE ATTM. MT TOPS MAY BE OBSCURED ACROSS THE SW
AND SC MTNS AT TIMES OVERNIGHT. OTHERWISE...ISOLD TS ACROSS THE
NORTHERN MTNS WILL LIKELY DIMINISH BY 03-04Z AGAIN THIS EVE.
INSTABILITY AND THEREFORE TS POTENTIAL IS UNCERTAIN FOR THURS. IF
MID AND HIGH LEVEL CLOUDS LINGER FROM OVERNIGHT SHOWERS...IT MAY
BE TOO STABLE FOR MUCH TS. REGARDLESS...AREAS SW OF A LINE FROM
KGUP TO KSRR WILL HAVE THE BEST CHANCE FOR PRECIP AFT 15Z.
34
&&
.PREV DISCUSSION...255 PM MDT WED AUG 28 2013...
A DEEP SUBTROPICAL MOISTURE SURGE HAS ARRIVED OVER SOUTHERN NM AS A
WELL DEFINED INVERTED TROUGH SHIFTS SLOWLY NORTHWEST OF THE AREA.
CIRA BLENDED TOTAL PWAT VALUES ARE 150-175PCT OF NORMAL OVER THE
EL PASO AREA...AND THIS MOISTURE WILL ADVECT NORTH THRU TONIGHT ON
INCREASING 700-500MB SSE FLOW. ABUNDANT CLOUD COVER HAS LIMITED
CONVECTION ACROSS MUCH OF THE SOUTH THUS FAR HOWEVER A SLUG OF
NMRS SHRA/TSRA DEVELOPING AROUND I-10 AND IS SLIDING NORTH. LATEST
RUC AND HRRR SHOW THIS MASS OF PRECIP MOVING NORTH UP THE RGV AND
SOUTHERN HIGH TERRAIN INTO THIS EVENING BEFORE TAPERING OFF AFTER
MIDNIGHT. HAVE TIGHTENED UP POPS FURTHER WITH FOCUS OVER CATRON...
SOCORRO...AND LINCOLN COUNTIES.
CLOUD COVER ASSCD WITH THIS AREA OF PRECIP WILL LINGER INTO EARLY
THURSDAY AND LIKELY LIMIT CONVECTION AGAIN UNTIL LATE DAY WITHIN
ITS PERIPHERY. MODELS DO SHOW A SIMILAR FEATURE TMRW BUT FARTHER
NORTH WITH A MASS OF SHRA/TSRA SLIDING ACROSS THE SW HIGH TERRAIN
AND SOUTHERN PORTIONS OF THE NM CONT DVD THRU MID DAY. CONVECTION
SHOULD BE MORE WIDESPREAD FOR THE REMAINDER OF THE HIGH TERRAIN
AFT 3 OR 4 PM AS THETA-E RIDGE VALUES ARE HIGHER AND LIFTED INDICES
MORE UNSTABLE.
THE REAL JUICE AND FORCING MOVES INTO THE REGION FRIDAY THRU MONDAY
WITH PWAT VALUES AVERAGING AROUND 1.2 INCHES. FOCUS FOR CONVECTION
WILL BE OVER NORTHERN AND WESTERN NM FRIDAY...THEN OVER CENTRAL
AND NORTHERN NM FOR SATURDAY THROUGH MONDAY AS A BACK DOOR FRONTAL
BNDRY MOVES SW OVER THE AREA. LCL HEAVY RAIN THREAT WILL INCREASE
AND FLASH FLOOD WATCHES ARE POSSIBLE FOR AT LEAST BURN SCAR AREAS
THRU THE LABOR DAY HOLIDAY. FOLKS PLANNING OUTDOOR ACTIVITIES OVER
THE HOLIDAY WEEKEND SHOULD PREPARE FOR WET WEATHER. TEMPS IN THIS
PATTERN WILL BE CLOSER TO SEASONAL NORMALS.
GUYER
.FIRE WEATHER...
BASED ON SATELLITE IMAGERY...ABUNDANT MOISTURE IS TRYING TO FLOW UP
FROM MEXICO. SOUTHERN PORTIONS OF THE AREA...ESPECIALLY SOCORRO
COUNTY WESTWARD WILL EXPERIENCE WETTING RAIN TODAY AND TONIGHT.
ISOLATED WETTING RAIN WILL BE FOUND FURTHER NORTH OVER THE NORTHWEST
AND NORTH CENTRAL MOUNTAINS. THE MID LEVEL DRY INTRUSION WHICH WAS
SQUARELY OVER THE FORECAST AREA YESTERDAY HAS SHIFTED
NORTH/NORTHEAST...THUS THE LOWEST HUMIDITY VALUES ARE FOUND THERE.
OVERALL...HUMIDITY VALUES HAVE TRENDED UP TODAY.
MOISTURE WILL CONTINUE TO MOVE NORTH AND WESTWARD ON THURSDAY. THIS
WILL SET THE STAGE FOR INCREASE WETTING RAIN COVERAGE CENTRAL
MOUNTAINS WESTWARD DURING THE AFTERNOON AND EVENING. A PRETTY DECENT
WETTING RAIN SIGNAL SHOWS UP ACROSS THE NORTHWEST AND WEST CENTRAL
HIGHLANDS. DRIER AND MORE STABLE AIR WILL BE FOUND OVER THE EASTERN
PLAINS. HUMIDITY VALUES FOR THE MOST PART WILL TREND UP EVEN MORE
ALTHOUGH LOWER SLIGHTLY ACROSS THE FAR EAST. HIGH TEMPERATURES WILL
BE ABOVE NORMAL NORTH AND EAST AS THE HIGH CENTER SHIFTS MORE OVER
PORTIONS OF THE SOUTHERN ROCKIES AND PLAINS INCLUDING OVER PARTS OF
NEW MEXICO. DUE TO THE PROXIMITY OF THE HIGH PRESSURE
ALOFT...VENTILATION RATES WILL LOWER ACROSS MOST OF THE AREA.
THE WEATHER MODELS DEPICT A BROAD HIGH PRESSURE AREA OVER THE DESERT
SOUTHWEST AND SOUTHERN ROCKIES FRIDAY INTO SATURDAY. SMALLER
ATMOSPHERIC WAVES WILL ROTATE AROUND THIS HIGH PRESSURE AREA AND
KICK OFF SCATTERED TO NUMEROUS WETTING THUNDERSTORMS. WESTERN AND
NORTHERN PORTIONS OF NM WILL MOST LIKELY EXPERIENCE THESE WAVES.
DRIER AND MORE STABLE AIR ALOFT WILL REMAINED CENTERED OVER EASTERN
NM. THE FLOW ALOFT WILL BE RATHER WEAK DURING THIS PERIOD SO SOME
POOR VENTILATION RATES SHOW UP IN AREAS. HIGH TEMPERATURES WILL
GENERALLY BE NEAR NORMAL WEST AND SEVERAL DEGREES ABOVE NORMAL EAST.
MINIMUM HUMIDITY VALUES WILL ALSO BE IN THE 20S EAST AND CANT RULE
OUT SOME UPPER TEENS. THUS CURING OF THE FINE OR GRASS FUELS WOULD MOST
LIKELY CONTINUE THERE.
BOTH THE GFS AND ECMWF MODELS SHOW AN UPTICK IN WETTING
THUNDERSTORMS OVER THE ENTIRE FORECAST AREA SUNDAY INTO EARLY NEXT
WEEK. THE UPPER HIGH WEAKENS SOME AND ALLOWS THE ATMOSPHERE TO
BECOME MORE UNSTABLE. ABUNDANT LOW LEVEL MOISTURE WOULD ALSO BEGIN
TO FILL IN ACROSS THE FORECAST AREA AND ALLOW FOR SCATTERED TO
NUMEROUS WETTING STORMS. THIS PERIOD COULD BECOME SOME SORT OF PSEUDO
MONSOON BURST EVENT. WILL CONTINUE TO MONITOR THE MODELS AND GET A
BETTER GAUGE FOR CONFIDENCE AS TIME GOES ON. CONDITIONS WOULD THEN
GRADUALLY IMPROVE SOME ACROSS THE EASTERN PLAINS.
50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 2 AM MDT THURSDAY FOR THE FOLLOWING ZONES...
NMZ508-526.
&&
$$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
853 PM EDT WED AUG 28 2013
.SYNOPSIS...
SMALL AMPLITUDE DISTURBANCES IN NW FLOW ALOFT WILL TRACK SOUTHEAST
THROUGH THE CAROLINAS OVERNIGHT. A WEAK COLD FRONT WILL TRACK SLOWLY
SOUTH THROUGH THE AREA ON THURSDAY. HIGH PRESSURE WILL BUILD INTO
THE MID-ATLANTIC AND CAROLINAS ON FRIDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 845 PM WEDNESDAY...
OVERVIEW:
NW FLOW ALOFT WILL PREVAIL OVER THE MID-ATLANTIC AND CAROLINAS
OVERNIGHT...BETWEEN AN EXPANSIVE H5 RIDGE CENTERED OVER THE CENTRAL
PLAINS/CENTRAL MS RIVER VALLEY AND H5 TROUGHING ALONG AND JUST
OFFSHORE THE EASTERN SEABOARD. SMALL AMPLITUDE DISTURBANCES IN NW
FLOW ALOFT OVER CENTRAL WV/VA AT 00Z (PER WV IMAGERY AND RAP DATA)
WILL TRACK SOUTHEAST ACROSS CENTRAL NC BETWEEN 03-12Z. IN THE LOWER
LEVELS...A BROAD SFC-H85 LOW CENTERED INVOF THE MASON-DIXON LINE AT
00Z WILL TRACK SOUTHEAST OFFSHORE THE DELMARVA COAST BY 12Z THU...
WITH AN ATTENDANT LOW-LEVEL TROUGH SINKING SLOWLY SOUTHWARD THROUGH
THE VIRGINIAS INTO CENTRAL NC.
PRECIP CHANCES:
REGIONAL RADAR INDICATED WIDESPREAD SHOWERS AND ISOLD THUNDERSTORMS
ACROSS WV/VA AT 00Z...IN ASSOC/W SMALL AMPLITUDE DISTURBANCES /DPVA/
IN NW FLOW ALOFT IN THE PRESENCE OF A VERY MOIST (PWAT 1.75-2.00")
AND MARGINALLY TO PERHAPS MODERATELY UNSTABLE AIRMASS. GIVEN DPVA
COINCIDENT (OR PERHAPS SLIGHTLY IN ADVANCE OF) AN APPROACHING
LOW-LEVEL TROUGH FROM THE NORTH IN THE PRESENCE OF A VERY MOIST AND
AT LEAST MARGINALLY UNSTABLE AIRMASS...IT SEEMS VERY REASONABLE THAT
CONVECTION ACROSS THE VIRGINIAS AT 00Z WILL EVENTUALLY PROGRESS S/SE
INTO CENTRAL NC BETWEEN MIDNIGHT AND SUNRISE. COVERAGE IS DIFFICULT
TO ASCERTAIN GIVEN BAD DIURNAL TIMING AND INCREASING NOCTURNAL
STABILIZATION. THOUGH DEEPER CONVECTION (I.E. THUNDER) WILL LIKELY
BECOME MORE SPORADIC IN NATURE AS THE NIGHT PROGRESSES...GIVEN
PLENTIFUL DEEP-LAYER MOISTURE AND AT LEAST MARGINAL INSTABILITY
(SFC-BASED OR ELEVATED)...A 50-60% CHANCE OF SHOWERS APPEARS
WARRANTED...WITH CHANCES INCREASING AROUND MIDNIGHT NEAR THE VA
BORDER AND TOWARD SUNRISE IN SOUTH/SE PORTIONS OF THE AREA. ALTHOUGH
A FEW THUNDERSTORMS CANNOT BE RULED OUT...WILL OPT TO LEAVE OUT
MENTION OF THUNDER PER THE ABOVE DISCUSSION. GIVEN DEEP-LAYER SHEAR
ON THE ORDER OF 35-40 KT...IT SHOULD BE NOTED THAT TRANSIENT
MID-LEVEL ROTATION AND DEVIANT MOTION WOULD BE EXPECTED WITH ISOLD
ROBUST UPDRAFTS (IF PRESENT)...THOUGH DECREASING INSTABILITY...WEAK
MID-LEVEL LAPSE RATES...INCREASING CIN...AND WEAK DCAPE WOULD
PRECLUDE STRONG CONVECTION.
TEMPERATURES:
EXPECT LOWS DICTATED PRIMARILY BY SHOWER ACTIVITY GIVEN WIDESPREAD
CLOUD COVER...IN THE LOWER TO MID 70S...WARMEST S/SW. -VINCENT
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 130 PM WEDNESDAY...
WITH STRONG CONTINENTAL HIGH PRESSURE OVER THE SOUTHERN CONUS...NC
WILL BE ON THE FRONT SIDE OF THE UPPER LEVEL RIDGE WITH SURFACE LOW
PRESSURE TRACKING ALONG THAT RIDGE JUST OFF THE CAROLINA COAST. A
COLD FRONT WILL CONTINUE TO MOVE THROUGH THE STATE THROUGHOUT THE
DAY. NORTHEASTERLY FLOW WILL PREVAIL BEHIND THE FRONT AS A WEAK
SURFACE HIGH BUILDS IN FROM THE NORTH. WRAP AROUND MOISTURE FROM THE
LOW OFFSHORE COULD HELP TO FUEL SOME SHOWERS AND THUNDERSTORMS AHEAD
OF THE FRONT AND TO THE SOUTH AND EAST. AT THIS TIME IT LOOKS LIKE
FRONTAL PASSAGE MAY OCCUR AT MOST AREAS PRIOR TO THE BEST DIURNAL
HEATING. MOST FORECAST SOUNDINGS DRY OUT CONSIDERABLY BY 15Z AND
THUS MOISTURE MAY BE LIMITED FOR AFTERNOON CONVECTION. THAT BEING
SAID...UP TO 1500 J/KG OF INSTABILITY AND 10-20 KNOTS OF SHEAR WILL
BE AVAILABLE TO WORK WITH AND IF THE FRONT MOVES THROUGH QUICK
ENOUGH OR WASHES OUT...THE SEA BREEZE COULD BECOME A FACTOR IN
DEVELOPING SOME SHOWERS LATE AFTERNOON/EARLY EVENING IN THE FAR
EAST. OVERNIGHT ON THURSDAY INTO FRIDAY...PRECIP CHANCES WILL TRAIL
OFF FROM NORTH TO SOUTH AS HIGH PRESSURE BUILDS IN.
DESPITE THE FRONTAL PASSAGE...HIGHS ARE STILL PROGGED TO BE IN THE
UPPER 80S NORTH TO LOW 90S SOUTH. LOW TEMPERATURES HOWEVER SHOULD
MAKE IT BACK DOWN INTO THE UPPER 60S.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 252 PM WEDNESDAY...
WESTWARD RETROGRESSION OF THE EXPANSIVE MID/UPPER LEVEL HIGH FROM
THE CENTRAL/SOUTHERN PLAINS INTO THE WESTERN US WILL RESULT IN
LOWERING HEIGHTS ALOFT WITH BROAD TROUGHINESS DEVELOPING OVER THE
EASTERN US BY THE WEEKEND. AFTER MOSTLY DRY CONDITIONS ON
FRIDAY...CENTRAL NC WILL BECOME MORE PRONE TO DIURNAL CONVECTION
BOTH SATURDAY AND SUNDAY...WITH BEST POPS OVER THE WESTERN PART OF
THE STATE IN AREAS OF DIFFERENTIAL HEATING NEAR THE
MOUNTAINS/FOOTHILLS. ADDITIONALLY...WILL HAVE TO BE ON THE LOOKOUT
FOR ANY SHORTWAVE DISTURBANCE EMBEDDED IN THE DEEP W-NWLY FLOW ALOFT
THAT COULD SERVE TO ENHANCE CONVECTIVE POTENTIAL/COVERAGE AT ANY
TIME.
BY MONDAY...BROAD TROUGH OVER THE EASTERN US TROUGH WILL BEGIN TO
DEEPEN IN RESPONSE TO AN AMPLIFYING NORTHERN STREAM ENERGY ADVANCING
EASTWARD THROUGH THE NORTHERN GREAT LAKES AND SOUTHERN CANADA. WHILE
THE AMPLITUDE OF THE EASTERN US TROUGH STILL REMAINS IN
QUESTION...RAIN CHANCES ARE EXPECTED TO INCREASE MONDAY AFTERNOON
INITIALLY WITH A WELL-DEFINED PRE-FRONTAL FRONTAL DEVELOPING ACROSS
CENTRAL NC AND THEN LATER MONDAY NIGHT AND INTO TUESDAY AS THE
ATTENDANT COLD FRONT PUSHES EAST INTO THE AREA...WITH THE POTENTIAL
FOR RAIN CHANCES TO LINGER INTO WEDNESDAY IF THE MORE
AMPLIFIED/SLOWER EC SOLUTION VERIFIES. UNTIL TIMING DISCREPANCIES
CAN BE BETTER RESOLVED WILL KEEP POPS CAPPED AT HIGH CHANCE (50 TO
54 PERCENT).
SEASONABLE TEMPERATURES THROUGH TUESDAY...AND THEN COOLER AND LESS
HUMID ON WEDNESDAY BEHIND THE FRONT.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 745 PM WEDNESDAY...
FIRST ROUND OF LIGHT RAIN HAS GENERALLY SHIFTED SOUTH AND EAST OF
THE FORECAST AREA...ALTHOUGH ANOTHER AREA OF PRECIP WAS MOVING
TOWARDS THE REGION FROM THE NORTHWEST. THIS NEXT AREA OF RAIN SHOULD
IMPACT THE AREA BETWEEN 03-09Z. HAVE LEFT ANY MENTION OF PRECIP OUT
OF THE TAFS FOR NOW...AS COVERAGE MAY BE SPOTTY AND CONFIDENCE OF
TIMING AND LOCATION IS LOW. HOWEVER...IT IS POSSIBLE THAT ANY
TERMINAL WILL SEE A SHOWER AND/OR LIGHT RAIN WHICH COULD BRIEFLY
RESULT IN SUB-VFR CONDITIONS. OTHERWISE...WITH A VERY MOIST LOW
LEVEL AIR MASS...MVFR VSBYS ARE EXPECTED ONCE AGAIN TONIGHT. A WEAK
COLD FRONT IS EXPECTED TO APPROACH THE AREA AROUND DAYBREAK ON
THURSDAY AND THEN MOVE ACROSS CENTRAL NC THROUGH THE MORNING HOURS.
THIS WILL ALLOW VSBYS TO IMPROVE AND THE WINDS TO BECOME
NORTHEASTERLY...LIKELY BY 14-17Z...WITH VFR CONDITIONS PREVAILING
FOR THE REMAINDER OF THE AFTERNOON.
OUTLOOK...EARLY MORNING FOG/STRATUS AND DIURNAL TYPE SHOWERS AND
THUNDERSTORMS ARE EXPECTED FOR THE REMAINDER OF THE PERIOD...
ALTHOUGH THE END OF THE WORK WEEK AND EARLY PART OF THE WEEKEND MAY
BE MOSTLY DRY. PRECIP COVERAGE WILL THEN INCREASE LATE IN THE
WEEKEND AND ESPECIALLY EARLY NEXT WEEK AS AN UPPER LEVEL TROUGH
STARTS TO DIG INTO THE EASTERN US.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...ELLIS
LONG TERM...CBL
AVIATION...KRR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1203 AM CDT TUE AUG 27 2013
.UPDATE...
ISSUED AT 1203 AM CDT TUE AUG 27 2013
LATEST LOCAL/REGIONAL RADAR SHOWS A DECAYING AREA OF SHOWERS AND
ISOLATED THUNDERSTORMS OVER THE TURTLE MOUNTAINS WITH ISOLATED
SHOWERS NEAR RICE LAKE AND MAX IN WARD AND MCLEAN COUNTIES. WATER
VAPOR IMAGERY SHOWS NORTH DAKOTA ON THE PERIMETER OF AN UPPER
RIDGE CENTERED OVER SOUTHEAST NEBRASKA. SEVERAL SHORTWAVES WILL
CONTINUE TO ROTATE AROUND THE HIGH AND SCOOT THROUGH NORTH DAKOTA.
THE HRRR MODEL IS CAPTURING A BROKEN AREA OF SHOWERS IN SOUTH
CENTRAL MONTANA ASSOCIATED WITH ANOTHER SHORTWAVE. THIS IS
FORECAST TO SHIFT INTO WESTERN NORTH DAKOTA BY AROUND 12Z. HAVE
ADJUSTED POPS TO ACCOUNT FOR THIS. OTHERWISE WILL MAINTAIN THE
MOSTLY CLEAR TO PARTLY CLOUDY SKIES OVERNIGHT WITH PATCHY FOG.
UPDATE ISSUED AT 946 PM CDT MON AUG 26 2013
AS OF 245 UTC...ONE LAST STORM REMAINS ACROSS NORTH CENTRAL NORTH
DAKOTA NEAR MOHALL. OTHERWISE...THUNDERSTORM ACTIVITY HAS QUICKLY
DIMINISHED WITH SUNSET AND THE LACK OF A LOW LEVEL JET. DID ADD
FOG TO MOST OF NORTHWEST AND CENTRAL NORTH DAKOTA GIVEN LIGHT
WINDS AND THE VERY HIGH HUMIDITY LEVELS IN PLACE.
UPDATE ISSUED AT 600 PM CDT MON AUG 26 2013
AS OF 2245 UTC...STRONG TO SEVERE THUNDERSTORMS CONTINUE TO
INTENSIFY ACROSS FAR NORTHEAST MONTANA THROUGH DUNN COUNTY IN
NORTH DAKOTA ALONG A WEAK CONVERGENCE LINE. ML CAPE VALUES NEAR
2500 J/KG ARE ANALYZED ALONG THIS LINE ON THE SPC RAPV2
MESOANALYSIS...WHICH APPEARS TO BE HANDLING THE CURRENT
ENVIRONMENT BETTER THAN THE RAPV1. GIVEN DEEP LAYER SHEAR OF 40
KTS...SUPERCELLS ARE LIKELY. THE PRIMARY THREATS ARE DAMAGING
WINDS WITH DOWNDRAFT CAPE VALUES NEAR 1200 J/KG. GIVEN THE HIGH
FREEZING LEVELS AND PWATS...HAIL SURVIVABILITY IS LIMITED. ALSO
MONITORING LOCATIONS NEAR THE SOUTH DAKOTA BORDER ALONG ANOTHER
CONVERGENCE LINE IN A SIMILIAR ENVIRONMENT...WITH THE LATEST 21
UTC HRRR CONTINUING TO SUGGEST CONTINUED GROWTH OF CONVECTION THAT
HAS BEEN INITIATING OVER THE PAST HOUR FOR THESE AREAS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 324 PM CDT MON AUG 26 2013
MAIN CONCERNS THIS SHORT TERM WILL BE THUNDERSTORMS. BROAD FEATURES
INCLUDE A LARGE AND PERSISTENT RIDGE IN THE UPPER ATMOSPHERE. ON THE
WESTERN SIDE OF THE RIDGE A TROPICAL PLUME IS IDENTIFIED ON THE
WATER VAPOR IMAGE. A WEAK SHORTWAVE NOW MOVING THROUGH NORTHEAST
WYOMING WILL SUPPORT CONVECTION THIS EVENING AND OVERNIGHT. AS THE
SHORT WAVE TROUGH TRANSITS ACROSS THE RIDGE EXPECT AN INCREASE IN
THUNDERSTORMS ...WHICH SO FAR TODAY APPEAR TO BY LIMITED BY THE WARM
MID LEVEL TEMPERATURES. WITH THE ADDED LIFT FROM THE SHORTWAVE
EXPECT THUNDERSTORMS TO BECOME MORE ACTIVE LATE THIS AFTERNOON AND
EVENING...MAINLY SOUTH CENTRAL AND SOUTHEAST. MULTIPLE WEAK OUTFLOW
BOUNDARIES EXIST ACROSS THE SOUTH CENTRAL...AND CLOUDS ACROSS NORTH
DAKOTA SUPPORTING DIFFERENTIAL HEATING AND ENHANCING THE THERMAL
BOUNDARY.
TONIGHT...THUNDERSTORM THREAT WILL MOVE EAST. ENDED THE CHANCE OF
THUNDERSTORMS AFTER 1 AM. SOUTHEAST UPSLOPE FLOW AND WEAK SHORTWAVE
ENERGY IN FLOW ALOFT WILL SUPPORT A SLIGHT CHANCE OF THUNDERSTORMS
SOUTHWEST TUESDAY AFTERNOON.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 324 PM CDT MON AUG 26 2013
MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH
TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES.
THE OVERALL UPPER LEVEL PATTERN REMAINS NEARLY UNCHANGED WITH A
CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND DETERMINISTIC
MODELS. FINER DETAILS CONTINUE TO COME TO A CONSENSUS AMONG THE
MODELS EARLY IN THE PERIOD...BUT SIGNIFICANT DIFFERENCES STILL EXIST
OVER THE WEEKEND AND EARLY NEXT WEEK. EXCEPT FOR A FEW ADJUSTMENTS
TO BUMP UP POPS WHERE MODELS ARE MORE IN LINE...STILL UTILIZED A
MODEL BLEND SOLUTION FOR POPS DURING MOST OF THE LONG TERM PERIOD.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...BETTER THUNDERSTORM CHANCES
APPEAR IN STORE TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WHEN A FEW
UPPER LEVEL WAVES MOVE INTO THE NORTHERN PLAINS AND TEMPORARILY
BREAKS DOWN THE UPPER LEVEL RIDGE. DETERMINISTIC MODELS INDICATE
INCREASED WARM ADVECTION WEDNESDAY AFTERNOON AND EVENING AHEAD OF
SURFACE LOW PRESSURE THAT DEVELOPS OVER THE WESTERN DAKOTAS. POPS
ARE GREATEST WEDNESDAY IN THE WEST HALF DURING THE DAY...WITH HIGHER
CHANCE POPS SPREADING EAST WEDNESDAY NIGHT AS THE INCREASED WARM
ADVECTION AND COOLING UPPER LEVEL TEMPERATURES WITH THE SHORTWAVES
SHOULD SUSTAIN CONVECTION AS IT TRANSLATES EAST.
THURSDAY AND THURSDAY NIGHT...THE LAST OF THIS ROUND OF UPPER LEVEL
SHORTWAVE ENERGY IMPULSES IS PROGGED TO MOVE EAST ACROSS THE STATE
THURSDAY BEFORE EXITING THE REGION THURSDAY AFTERNOON/NIGHT. UPPER
LEVEL RIDGING QUICKLY REBOUNDS ON THURSDAY NIGHT.
FRIDAY THROUGH MONDAY...THE MODELS IN GENERAL KEEP THE UPPER LEVEL
RIDGE ESTABLISHED OVER THE CENTRAL US THROUGH THE WEEKEND. THE
MODELS DIFFER AFTER THIS...WITH THE ECMWF KEEPING THE RIDGE IN PLACE
WHILE THE GFS SOLUTION DEPICTS THE RIDGE BROADENING AND MOVING EAST.
THUS WILL CONTINUE WITH A MODEL BLEND HERE WHICH GIVES MAINLY SLIGHT
CHANCE POPS EACH DAY.
TEMPERATURES SHOULD REMAIN ABOVE AVERAGE THROUGH SATURDAY WITH HIGHS
MAINLY 85-90 NORTH TO LOW TO MID 90S SOUTH. THE MODEL BLEND HINTS OF
TEMPERATURES MOVING BACK TOWARDS SEASONABLE SUNDAY/MONDAY WITH HIGHS
75-85 NORTH AND IN THE 80S SOUTH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1203 AM CDT TUE AUG 27 2013
PATCHY FOG WITH BRIEF IFR/MVFR VSBYS CAN BE EXPECTED AT
KMOT/KBIS/KJMS THROUGH 13Z TUESDAY. OTHERWISE SCT/BKN VFR CIGS
NEXT 24HR. ISOLATED SHOWERS AND THUNDERSTORMS REMAIN A POSSIBILITY
AS WELL.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...WAA
LONG TERM...JV
AVIATION...KS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
215 PM EDT TUE AUG 27 2013
.SYNOPSIS...
WEAK SHORTWAVES CROSSES TODAY...UNDER NORTHWEST FLOW ALOFT. COLD
FRONT CROSSES WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE VISITS
BRIEFLY FRIDAY BEFORE PATTERN REPEATS.
&&
.NEAR TERM /THROUGH TONIGHT/...
1115 AM UPDATE. ADJUSTED LIKELY POPS TO POTENTIAL NEW MCS
DEVELOPMENT UPSTREAM FAIRLY EARLY THIS AFTERNOON...THEN DROPPING
SOUTH SOUTHEAST.
PREVIOUS DISCUSSION...
HIGH LEVEL CLOUDS ASSOCIATED WITH A DYING MCS ACROSS LAKE MICHIGAN
WILL COVER THE AREA THIS MORNING. NORTHWEST FLOW ALOFT...AND
EMBEDDED SHORTWAVES ARE EVIDENT IN VORT MAX FIELD ON H5 CHARTS.
ALTHOUGH IT LOOKS LIKE CONVECTIVE FEEDBACK...PIECES OF ENERGY
LOOKS REAL ACTING AS FORCING MECHANISMS.
THE HRRR MODEL BRINGS REMNANTS OF GREAT LAKES MCS OVER CKB...EKN
AND NORTHEAST MOUNTAINS THIS AFTERNOON. ANOTHER SHORTWAVE IS
EVIDENT IN H5 CHARTS APPROACHING THE AREA FROM THE NORTHWEST
WEDNESDAY.
NAM AND RUC MODELS SUGGEST AFTERNOON AND EVENING CONVECTION IN QPF
AND SFC CAPE FIELDS ALTHOUGH THE LATER LOOKS OVERDONE BY THE NAM
WITH DEWPOINTS IN THE LOW TO MID 70S. AN AREA OF DEEP LAYERED
SHEAR MOVES INTO SOUTHEAST OH AND PORTIONS OF WV THIS AFTERNOON.
EXPECT CONVECTIVE INITIATION WITH FEW STORMS BUT DO NOT EXPECT
THEM TO BECOME SEVERE.
CODED SKY AND POP GRIDS PER LATEST SATELLITE AND RADAR IMAGES. MID
LEVEL CLOUDS ADVECTING FROM THE NORTHWEST ACROSS SOUTHEAST OHIO
SITES SUCH AS PKB AND HTS EARLY THIS MORNING.
USED THE CONS MOS FOR TEMPERATURE THROUGH THE PERIOD.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ACTIVE WEATHER MAINLY THE FIRST HALF OF THE SHORT TERM PERIOD...WITH
PRECIP CHANCES AND POSSIBLE SUBSEQUENT HYDRO ISSUES PRIMARILY WED
AND WED NIGHT.
WEDNESDAY...AREA REMAINS UNDER NORTHWEST FLOW ALOFT WHILE AT THE SFC
SOUTHWEST WINDS IN PLACE. THOUGH DIFFS EXIST WITH STRENGTH AND
PLACEMENT...CONSENSUS OF NWP OUTPUT IS IN FAIRLY DECENT AGREEMENT
DRAGGING A COUPLE OF VORT MAXES ACROSS THE NORTHEASTERN ZONES FROM
NW TO SE ON WED. FIRST RIPPLE PUSHES INTO THE AREA RIGHT AROUND 12Z
WED AND OVER THE CENTRAL PART OF THE AREA BY 18Z WED. APPEARS THE
BEST OVERALL MOISTURE DEPTH NOT REALLY CO-LOCATED WITH BEST OVERALL
FORCING INITIALLY...WITH THE BEST MOISTURE OVER THE NE ZONES AND
BETTER DYNAMIC FORCING STILL TO THE WEST AND NORTHWEST AT 12Z WED.
HOWEVER OMEGA FIELDS INDICATE AMPLE LIFT THROUGH A DEEP LAYER ACROSS
THE NE ZONES AND WITH PLENTY OF MOISTURE IN PLACE WILL CONTINUE
CATEGORICAL POPS NE ZONES AT THE OUTSET. EXPECT SHOWERS AND
THUNDERSTORMS TO QUICKLY RAMP UP ACROSS THE NORTH AND NW ZONES AS
WELL DURING THE MORNING HOURS WITH THE APPROACH OF THE
AFOREMENTIONED VORT MAX AND ITS ASSOC LIFT...AS WELL AS LARGE SCALE
FORCING FOR ASCENT. BY THE AFTERNOON HOURS THE NEXT VORT MAX ON
NORTHWEST FLOW ALOFT PUSHES INTO THE NW ZONES BY 00Z THU. MODELS
STILL DIFFER ON THE PLACEMENT OF THE ASSOC SFC LOW...ALTHOUGH THEY
ARE TRYING TO COME CLOSER TOGETHER. STILL...LATEST NAM DEPICTS SFC
LOW STILL WELL WEST NEAR CINCINNATI AT 00Z THU WHILE OP GUIDANCE HAS
IT FURTHER EAST/NORTHEAST IN THE AREA OF OUR SE OHIO ZONES. GEFS
MEAN AND ITS MEMBERS SUPPORT THE FURTHER EAST SOLN AS DOES THE SREF
MEAN AND THUS WILL LEAN THE FORECAST IN THIS DIRECTION...WITH THE
LOW AND FRONT ENTERING INTO NW ZONES BY 00Z THU. ALL IN ALL WILL
CONTINUE TO TREND HIGHEST POPS FROM THE NE ZONES TOWARDS THE CENTRAL
AND SOUTHERN ZONES BY 00Z THU. EXPANDED THE COVERAGE OF CATEGORICAL
POPS TO INCLUDE GENERALLY LOCATIONS ALONG AND NORTHEAST OF A
BKW-CRW-PERRY COUNTY OH LINE AS IN THE END MOST IF NOT ALL OF THOSE
LOCATIONS SHOULD SEE SOME MEASURABLE RAINFALL BY DAY/S END ON
WEDNESDAY...THOUGH PINPOINTING THE TIMING ISN/T QUITE SO
STRAIGHTFORWARD. QPF AMOUNTS STILL RUNNING AROUND 0.75IN TO
1.00IN...AND WITH 3-HR FFG GUIDANCE AROUND 2 INCHES THERE IS CONCERN
FOR THE POSSIBILITY OF FLASH FLOODING. STILL NOT QUITE ENOUGH
CONFIDENCE TO ISSUE A WATCH AT THIS POINT AND WILL LET THE DAYSHIFT
TAKE ONE MORE LOOK AT IT. WILL CONTINUE HYDRO CONCERN MENTION
HOWEVER IN HWO AND DID GO AHEAD AND INCLUDE HEAVY RAIN WORDING IN
THE WX GRIDS WED.
PRECIP EXPECTED TO COME TO AN END FROM NW TO SE OVERNIGHT WED NIGHT
AS THE FRONT SWEEPS ACROSS THE AREA. MOST LOCATIONS WILL BE DRY ON
THURSDAY WITH THE FRONT WELL EAST OF THE AREA UNDER A PARTLY CLOUDY
SKY AND HIGHS GENERALLY IN THE MID 80S FOR LOWLAND LOCATIONS. WILL
KEEP INHERITED SLIGHT CHANCE AND LOW CHANCE POPS FOR THE
EAST/SOUTHEAST HIGH TERRAIN WITH A DECENT SLUG OF LLVL MOISTURE
REMAINING ALONG WITH SFC CONVERGENCE ON THE RIDGETOPS PROGGED.
THURSDAY NIGHT ALL LOCATIONS SHOULD DRY OUT WITH THE LOSS OF DAYTIME
HEATING. SFC HIGH PRESSURE CONTINUES TO MOVE EASTWARD AWAY FROM THE
AREA WITH RETURN SOUTHEAST FLOW SETTING UP. THIS...ALONG WITH
ANOTHER S/W TROUGH AND ASSOC VORT MAX MOVING INTO THE NORTHERN ZONES
BY AND AFTER 06Z FRI LENDS SOME POTENTIAL FOR LIGHT SHOWER
REDEVELOPMENT ON THE EAST SLOPES TOWARDS THE DAWN HOURS FRIDAY
MORNING. WILL LEAVE FORECAST DRY FOR NOW.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
GENERALLY FOLLOWED HPC IN EXTENDED WHICH WILL FEATURE QUIETER AND
DRIER WX DESPITE CONTINUING NW FLOW ALOFT. TEMPS RUNNING IN MID
80S AND LOWS GENERALLY IN 60S. GUIDANCE CONT TO RUN ON WARM
SIDE...AS HAS BEEN THE CASE MUCH OF THIS SUMMER. THINK WITH WET
GROUNDS THIS SEASON...FELT HEDGING A LITTLE BELOW GUIDANCE WAS
WARRANTED.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
18Z TUESDAY THRU 18Z WEDNESDAY...
GENERALLY VFR CEILINGS OUTSIDE OF ANTICIPATED MCS REDEVELOPMENT JUST
NORTH OF OUR AREA BY 19Z...DROPPING SOUTHEAST REMAINDER OF
AFTERNOON...REACHING EAST PORTIONS OF AREA BY 00Z. MAIN EFFECT OF
THE COMPLEX WILL BE IN THE PKB...CKB...EKN...TERMINALS. SO WILL
CARRY PREVAILING SHRA.TSRA THESE TERMINAL AND VCTS ELSEWHERE.
EXPECT RAPID WEAKENING SHORTLY AFTER 00Z...OF WHICH AN MVFR CEILING
MAY FORM BEHIND THE DYING COMPLEX.
DIFFICULT TO PROJECT THE NEXT IF ANY MCS LATER TONIGHT...BUT WILL
REDO THE SAME AREA AFTER 06Z FOR ORGANIZED CONVECTION. WILL KEEP
MOSTLY VFR OVERNIGHT THOSE AREAS THAT DO NOT RECEIVE RAIN...DUE TO
EXPECTED CLOUDS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY...
FORECAST CONFIDENCE: LOW TO MEDIUM.
ALTERNATE SCENARIOS: TIMING AND COVERAGE OF CONVECTION COULD VARY
THRU THE PERIOD...ALONG WITH DEVELOPMENT OF OVERNIGHT STRATUS/FOG.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY H H H M M M M M H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H M M M M H H H H H H H
CKB CONSISTENCY H H H H H H H H H M H H
AFTER 18Z WEDNESDAY...
IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS WEDNESDAY
AFTERNOON...MAINLY SOUTH.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KMC/JMV/30
NEAR TERM...ARJ/JMV
SHORT TERM...30
LONG TERM...30
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
141 PM EDT TUE AUG 27 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE OVER THE GULF STATES AND UPPER LEVEL HIGH
PRESSURE IN THE CENTRAL PLAINS WILL DOMINATE THE WEATHER MAP FOR
THE NEXT FEW DAYS. A COLD FRONT WILL TRACK FROM THE WESTERN GREAT
LAKES THROUGH THE OHIO VALLEY ON WEDNESDAY. BEHIND THIS...HIGH
PRESSURE AT THE SURFACE WILL SETTLE OVER NORTHERN OHIO FOR A DRIER
YET STILL WARM PERIOD AT THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MID LEVEL RIDGE CENTERED OVER THE CENTRAL UNITED STATES WILL KEEP
OUR REGION IN NORTHWEST FLOW ALOFT. REMNANT MCS CURRENTLY DROPPING
DOWN ACROSS NORTHERN OHIO SHOULD CONTINUE TO WEAKEN THROUGH THE
REST OF THIS MORNING BUT SOME ISOLATED SHOWER/THUNDERSTORM
ACTIVITY WILL LIKELY AFFECT OUR FAR NORTHEAST. DEBRIS CLOUDS
ASSOCIATED WITH THIS WILL LINGER ACROSS AT LEAST THE NORTHEAST HALF
OF OUR FA INTO EARLY AFTERNOON. THIS WILL RESULT IN SOME
UNCERTAINTY AS TO HOW MUCH DESTABILIZATION WE WILL SEE LATER THIS
AFTERNOON. WOULD EXPECT CLOUDS TO THIN/DISSIPATE ENOUGH TO ALLOW
FOR SOME RECOVERY THOUGH...RANGING FROM THE UPPER 80S NORTHEAST TO
NEAR 90 POSSIBLY LOWER 90S ACROSS OUR FAR SOUTHWEST. THIS WILL
RESULT IN ML CAPES IN THE 1500 TO POSSIBLY AS HIGH 2500 J/KG
RANGE LATE THIS AFTERNOON...WITH A SOUTHWEST TO NORTHEAST GRADIENT
ACROSS OUR AREA. BIG QUESTION IS TRACK/TIMING/INTENSITY OF
SECONDARY REMNANT MCS NOW PUSHING DOWN INTO NORTHERN MI. LATEST
NAM/RAP SUGGESTING THE BEST ACTIVITY ASSOCIATED WITH THIS WILL
REMAIN MORE OFF TO OUR NORTHEAST WHILE THE LATEST HRRR IS
INDICATING IT MAY TRACK A LITTLE FARTHER WEST LATE THIS AFTERNOON.
THINK BEST GUESS WOULD BE THAT IT WILL TRACK DOWN ALONG THE
NORTHEAST EDGE OF THE BETTER INSTABILITY GRADIENT...WHICH WOULD
ALLOW FOR IT TO AFFECT AT LEAST OUR NORTHEASTERN AREAS. AS A
RESULT...WILL BUMP UP POPS ACROSS ABOUT THE NORTHEAST THIRD OF
OUR FA...BUT STILL KEEP THEM IN THE HIGH CHANCE CATEGORY DUE TO
THE UNCERTAINTY. BEST DEEP AND MID LAYER SHEAR WILL ALSO REMAIN
ALONG AND NORTHEAST OF OUR FA LATER TODAY SO EXPECT BEST CHANCE
FOR ANY SEVERE STORMS THROUGH THIS AFTERNOON TO BE ACROSS OUR
NORTHEASTERN. THE PRIMARY SEVERE THREAT WOULD BE DAMAGING WINDS
AND POSSIBLY LARGE HAIL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
IF IT WAS NOT STATED IN THE NEAR TERM...MODELS ARE NOT HANDLING
THE ONGOING WEATHER WELL AND DIFFER VASTLY IN THEIR INTERPRETATION
OF THE STATE OF THE WEATHER IN THE SHORT TERM. THE HIGH
TEMPERATURES REACHING INTO THE 90S AND INCREASED MOISTURE THROUGH
THE PERIOD WILL LEAD TO INCREASED THREAT FOR STORMS...ESPECIALLY
ON WEDNESDAY AS A FAIRLY PREDICTABLE COLD FRONT WORKS THROUGH THE
OHIO VALLEY AND SPARKS CONVECTIVE ACTIVITY.
THE LIKELY CHANCES OF STORMS IN THE LATE AFTERNOON AND EVENING
WERE NOT AS CUT AND DRY AS I WOULD PREFER TO CARRY SO POPS WERE
LOWERED FOR THIS TIME TO JUST CHANCE. THE BETTER CHANCE FOR
SHOWERS ON WEDNESDAY WILL OCCUR IN THE NORTHEAST BUT COULD BE
COMPROMISED BY CLOUD COVER LIMITING THE SURFACE BASED INSTABILITY
THAT WILL BE NECESSARY FOR STORMS TO PROGRESS. THIS CLOUD COVER
WILL ALSO PUT THE DAYS HIGH TEMPERATURES IN QUESTION WHERE THE
FORECAST UPPER 80S COULD BE 5 DEGREES TOO HIGH OR SO.
DRIER AIR IN THE WAKE OF THE COLD FRONT WILL BE THE DIFFERENCE IN
THE AIRMASS...NOT NECESSARILY COLDER TEMPERATURES.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
NUMERICAL MODEL SOLNS SHOWING WEAK PERTURBATIONS DROPPING SE
AROUND THE PERIPHERY OF THE MID LEVEL RIDGE. THEREFORE...CAN NOT
RULE OUT VERY LOW POP/ISOLD SHOWERS/THUNDERSTORMS TOWARD THE END
OF THE WEEK INTO NEXT WEEKEND. THESE FEATURES ARE WEAK AND
DIFFICULT TO TIME...AND WITH PROB BEING SO LOW WILL MAINTAIN DRY
FCST THRU FRIDAY NIGHT AND THEN ONLY ALLOW A SLIGHT CHANCE MAINLY
ACROSS THE WEST SATURDAY AFTN. ON SUNDAY A LITTLE MORE SIGNIFICANT
S/W MAY LEAD TO PRECIPITATION. WILL CONTINUE TO LIMIT POPS TO
CHANCE CATEGORY WITH THIS FEATURE. TEMPERATURES REMAIN CLOSE TO 10
DEGREES ABOVE NORMAL WITH HIGHS SAT/SUN UPPER 80S NE TO LOWER 90S
SW.
DETERMINISTIC NUMERICAL MODEL SOLNS HAVE BEEN DIFFERING ON HOW MUCH
THE MID/UPR LEVEL RIDGE PUSHES BACK EAST INTO THE OHIO VALLEY. 00Z
GFS BEING MORE AGGRESSIVE WITH THE RIDGE THAN THE ECMWF AND WAS
HOLDING THE SFC FRONT TO OUR NORTH...WHILE ECMWF WAS PUSHING THE
FRONT THRU ON MONDAY. 12Z DETERMINISTIC GFS RUN HAS TRENDED MORE
TOWARD THE ECMWF...SO WILL ALLOW FOR AN INCREASE IN POPS DURG THE
DAY MONDAY TO ACCOUNT FOR THIS FRONT. TEMPERATURES SLIGHTLY COOLER
MONDAY WITH HIGHS RANGING FROM MID 80S NORTH TO UPPER 80S SOUTH.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
REMNANTS OF EARLIER MCS OVER NORTHEAST OHIO HAVE PRETTY MUCH
DISSIPATED BUT A FAIR AMOUNT OF DEBRIS CLOUDINESS IS LINGERING
ACROSS OUR AREA THIS AFTERNOON. AS A RESULT...TEMPERATURES AND
INSTABILITY ARE STRUGGLING SOMEWHAT TO RECOVER. MODELS ARE HAVING A
DIFFICULT TIME RESOLVING HOW TO HANDLE POSSIBLE REDEVELOPMENT
LATER TODAY INTO TONIGHT WITH THE REMNANTS OF THE SECONDARY MCS PUSHING
DOWN ACROSS LOWER MICHIGAN. THE 12Z GFS/NAM/CMC ARE GENERALLY
KEEPING THE BEST ACTIVITY WITH THIS OFF TO OUR NORTHEAST..BUT
SOME OF THE HIGHER RES MODELS ARE SUGGESTING SOME DEVELOPMENT
FARTHER WEST INTO THE BETTER INSTABILITY. WILL GO AHEAD AND ALLOW
FOR A VCTS FOR KCMH/KLCK HEADING INTO THIS EVENING TO COVER THE
THREAT. TOUGH TO RULE OUT AN ISOLATED CHANCE AT THE OTHER TAF
SITES BUT WILL LEAVE THEM DRY DUE TO THE LOW PROBABILITY/UNCERTAINTY.
A COLD FRONT WILL SAG SOUTHEAST TOWARD THE AREA LATER TONIGHT INTO
WEDNESDAY MORNING. AHEAD OF THIS A DEVELOPING WESTERLY LOW JET
WILL NOSE INTO NORTHERN OHIO LATE TONIGHT. THIS COULD LEAD TO SOME
ADDITIONAL REDEVELOPMENT ACROSS OUR NORTH BUT THE BETTER FORCING
APPEARS TO REMAIN TO OUR NORTHEAST. WILL THEREFORE TREND TOWARD A
DRIER SOLUTION AND JUST ALLOW FOR A VCSH AT KCMH/KLCK LATE IN THE
TAF PERIOD.
OUTLOOK...THUNDERSTORMS POSSIBLE WEDNESDAY INTO WEDNESDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...JGL
SHORT TERM...FRANKS
LONG TERM...AR
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1129 AM EDT TUE AUG 27 2013
.SYNOPSIS...
WEAK SHORTWAVES CROSSES TODAY...UNDER NORTHWEST FLOW ALOFT. COLD
FRONT CROSSES WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE VISITS
BRIEFLY FRIDAY BEFORE PATTERN REPEATS.
&&
.NEAR TERM /THROUGH TONIGHT/...
1115 AM UPDATE. ADJUSTED LIKELY POPS TO POTENTIAL NEW MCS
DEVELOPMENT UPSTREAM FAIRLY EARLY THIS AFTERNOON...THEN DROPPING
SOUTH SOUTHEAST.
PREVIOUS DISCUSSION...
HIGH LEVEL CLOUDS ASSOCIATED WITH A DYING MCS ACROSS LAKE MICHIGAN
WILL COVER THE AREA THIS MORNING. NORTHWEST FLOW ALOFT...AND
EMBEDDED SHORTWAVES ARE EVIDENT IN VORT MAX FIELD ON H5 CHARTS.
ALTHOUGH IT LOOKS LIKE CONVECTIVE FEEDBACK...PIECES OF ENERGY
LOOKS REAL ACTING AS FORCING MECHANISMS.
THE HRRR MODEL BRINGS REMNANTS OF GREAT LAKES MCS OVER CKB...EKN
AND NORTHEAST MOUNTAINS THIS AFTERNOON. ANOTHER SHORTWAVE IS
EVIDENT IN H5 CHARTS APPROACHING THE AREA FROM THE NORTHWEST
WEDNESDAY.
NAM AND RUC MODELS SUGGEST AFTERNOON AND EVENING CONVECTION IN QPF
AND SFC CAPE FIELDS ALTHOUGH THE LATER LOOKS OVERDONE BY THE NAM
WITH DEWPOINTS IN THE LOW TO MID 70S. AN AREA OF DEEP LAYERED
SHEAR MOVES INTO SOUTHEAST OH AND PORTIONS OF WV THIS AFTERNOON.
EXPECT CONVECTIVE INITIATION WITH FEW STORMS BUT DO NOT EXPECT
THEM TO BECOME SEVERE.
CODED SKY AND POP GRIDS PER LATEST SATELLITE AND RADAR IMAGES. MID
LEVEL CLOUDS ADVECTING FROM THE NORTHWEST ACROSS SOUTHEAST OHIO
SITES SUCH AS PKB AND HTS EARLY THIS MORNING.
USED THE CONS MOS FOR TEMPERATURE THROUGH THE PERIOD.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ACTIVE WEATHER MAINLY THE FIRST HALF OF THE SHORT TERM PERIOD...WITH
PRECIP CHANCES AND POSSIBLE SUBSEQUENT HYDRO ISSUES PRIMARILY WED
AND WED NIGHT.
WEDNESDAY...AREA REMAINS UNDER NORTHWEST FLOW ALOFT WHILE AT THE SFC
SOUTHWEST WINDS IN PLACE. THOUGH DIFFS EXIST WITH STRENGTH AND
PLACEMENT...CONSENSUS OF NWP OUTPUT IS IN FAIRLY DECENT AGREEMENT
DRAGGING A COUPLE OF VORT MAXES ACROSS THE NORTHEASTERN ZONES FROM
NW TO SE ON WED. FIRST RIPPLE PUSHES INTO THE AREA RIGHT AROUND 12Z
WED AND OVER THE CENTRAL PART OF THE AREA BY 18Z WED. APPEARS THE
BEST OVERALL MOISTURE DEPTH NOT REALLY CO-LOCATED WITH BEST OVERALL
FORCING INITIALLY...WITH THE BEST MOISTURE OVER THE NE ZONES AND
BETTER DYNAMIC FORCING STILL TO THE WEST AND NORTHWEST AT 12Z WED.
HOWEVER OMEGA FIELDS INDICATE AMPLE LIFT THROUGH A DEEP LAYER ACROSS
THE NE ZONES AND WITH PLENTY OF MOISTURE IN PLACE WILL CONTINUE
CATEGORICAL POPS NE ZONES AT THE OUTSET. EXPECT SHOWERS AND
THUNDERSTORMS TO QUICKLY RAMP UP ACROSS THE NORTH AND NW ZONES AS
WELL DURING THE MORNING HOURS WITH THE APPROACH OF THE
AFOREMENTIONED VORT MAX AND ITS ASSOC LIFT...AS WELL AS LARGE SCALE
FORCING FOR ASCENT. BY THE AFTERNOON HOURS THE NEXT VORT MAX ON
NORTHWEST FLOW ALOFT PUSHES INTO THE NW ZONES BY 00Z THU. MODELS
STILL DIFFER ON THE PLACEMENT OF THE ASSOC SFC LOW...ALTHOUGH THEY
ARE TRYING TO COME CLOSER TOGETHER. STILL...LATEST NAM DEPICTS SFC
LOW STILL WELL WEST NEAR CINCINNATI AT 00Z THU WHILE OP GUIDANCE HAS
IT FURTHER EAST/NORTHEAST IN THE AREA OF OUR SE OHIO ZONES. GEFS
MEAN AND ITS MEMBERS SUPPORT THE FURTHER EAST SOLN AS DOES THE SREF
MEAN AND THUS WILL LEAN THE FORECAST IN THIS DIRECTION...WITH THE
LOW AND FRONT ENTERING INTO NW ZONES BY 00Z THU. ALL IN ALL WILL
CONTINUE TO TREND HIGHEST POPS FROM THE NE ZONES TOWARDS THE CENTRAL
AND SOUTHERN ZONES BY 00Z THU. EXPANDED THE COVERAGE OF CATEGORICAL
POPS TO INCLUDE GENERALLY LOCATIONS ALONG AND NORTHEAST OF A
BKW-CRW-PERRY COUNTY OH LINE AS IN THE END MOST IF NOT ALL OF THOSE
LOCATIONS SHOULD SEE SOME MEASURABLE RAINFALL BY DAY/S END ON
WEDNESDAY...THOUGH PINPOINTING THE TIMING ISN/T QUITE SO
STRAIGHTFORWARD. QPF AMOUNTS STILL RUNNING AROUND 0.75IN TO
1.00IN...AND WITH 3-HR FFG GUIDANCE AROUND 2 INCHES THERE IS CONCERN
FOR THE POSSIBILITY OF FLASH FLOODING. STILL NOT QUITE ENOUGH
CONFIDENCE TO ISSUE A WATCH AT THIS POINT AND WILL LET THE DAYSHIFT
TAKE ONE MORE LOOK AT IT. WILL CONTINUE HYDRO CONCERN MENTION
HOWEVER IN HWO AND DID GO AHEAD AND INCLUDE HEAVY RAIN WORDING IN
THE WX GRIDS WED.
PRECIP EXPECTED TO COME TO AN END FROM NW TO SE OVERNIGHT WED NIGHT
AS THE FRONT SWEEPS ACROSS THE AREA. MOST LOCATIONS WILL BE DRY ON
THURSDAY WITH THE FRONT WELL EAST OF THE AREA UNDER A PARTLY CLOUDY
SKY AND HIGHS GENERALLY IN THE MID 80S FOR LOWLAND LOCATIONS. WILL
KEEP INHERITED SLIGHT CHANCE AND LOW CHANCE POPS FOR THE
EAST/SOUTHEAST HIGH TERRAIN WITH A DECENT SLUG OF LLVL MOISTURE
REMAINING ALONG WITH SFC CONVERGENCE ON THE RIDGETOPS PROGGED.
THURSDAY NIGHT ALL LOCATIONS SHOULD DRY OUT WITH THE LOSS OF DAYTIME
HEATING. SFC HIGH PRESSURE CONTINUES TO MOVE EASTWARD AWAY FROM THE
AREA WITH RETURN SOUTHEAST FLOW SETTING UP. THIS...ALONG WITH
ANOTHER S/W TROUGH AND ASSOC VORT MAX MOVING INTO THE NORTHERN ZONES
BY AND AFTER 06Z FRI LENDS SOME POTENTIAL FOR LIGHT SHOWER
REDEVELOPMENT ON THE EAST SLOPES TOWARDS THE DAWN HOURS FRIDAY
MORNING. WILL LEAVE FORECAST DRY FOR NOW.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
GENERALLY FOLLOWED HPC IN EXTENDED WHICH WILL FEATURE QUIETER AND
DRIER WX DESPITE CONTINUING NW FLOW ALOFT. TEMPS RUNNING IN MID
80S AND LOWS GENERALLY IN 60S. GUIDANCE CONT TO RUN ON WARM
SIDE...AS HAS BEEN THE CASE MUCH OF THIS SUMMER. THINK WITH WET
GROUNDS THIS SEASON...FELT HEDGING A LITTLE BELOW GUIDANCE WAS
WARRANTED.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
16Z TUESDAY THRU 12Z WEDNESDAY...
MVFR CEILINGS/HAZE TIL AROUND 18Z...THEN VFR CEILINGS OUTSIDE OF
ANTICIPATED MCS REDEVELOPMENT JUST NORTH OF OUR AREA BY
19Z...DROPPING SOUTH SOUTHEAST REMAINDER OF AFTERNOON...REACHING
SOUTHEAST PORTIONS OF AREA BY 00Z. EXPECT SOUTHWEST PORTIONS OF AREA
INCLUDING HTS TO ESCAPE THIS. OTHERWISE...WILL CARRY PREVAILING
SHRA/TSRA FROM NORTHWEST TO SOUTHEAST FOR ABOUT A 3 HOUR PERIOD AT
OTHER TAF SITES. EXPECT RAPID WEAKENING SHORTLY AFTER 00Z...OF WHICH
AN MVFR CEILING MAY FORM BEHIND THE DYING COMPLEX.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: TIMING AND COVERAGE OF CONVECTION COULD VARY
THIS AFTERNOON AND EVENING...ALONG WITH DEVELOPMENT OF OVERNIGHT
STRATUS/FOG.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EDT 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21
CRW CONSISTENCY M M H H H H M M M H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H M H H H H H M M H H H
EKN CONSISTENCY M H H H H H H H H H H H
PKB CONSISTENCY H H H H M H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z WEDNESDAY...
IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KMC/JMV/30
NEAR TERM...ARJ/JMV
SHORT TERM...30
LONG TERM...30
AVIATION...ARJ/JMV
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
959 AM EDT TUE AUG 27 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE OVER THE GULF STATES AND UPPER LEVEL HIGH
PRESSURE IN THE CENTRAL PLAINS WILL DOMINATE THE WEATHER MAP FOR
THE NEXT FEW DAYS. A COLD FRONT WILL TRACK FROM THE WESTERN GREAT
LAKES THROUGH THE OHIO VALLEY ON WEDNESDAY. BEHIND THIS...HIGH
PRESSURE AT THE SURFACE WILL SETTLE OVER NORTHERN OHIO FOR A DRIER
YET STILL WARM PERIOD AT THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MID LEVEL RIDGE CENTERED OVER THE CENTRAL UNITED STATES WILL KEEP
OUR REGION IN NORTHWEST FLOW ALOFT. REMNANT MCS CURRENTLY DROPPING
DOWN ACROSS NORTHERN OHIO SHOULD CONTINUE TO WEAKEN THROUGH THE
REST OF THIS MORNING BUT SOME ISOLATED SHOWER/THUNDERSTORM
ACTIVITY WILL LIKELY AFFECT OUR FAR NORTHEAST. DEBRIS CLOUDS
ASSOCIATED WITH THIS WILL LINGER ACROSS AT LEAST THE NORTHEAST HALF
OF OUR FA INTO EARLY AFTERNOON. THIS WILL RESULT IN SOME
UNCERTAINTY AS TO HOW MUCH DESTABILIZATION WE WILL SEE LATER THIS
AFTERNOON. WOULD EXPECT CLOUDS TO THIN/DISSIPATE ENOUGH TO ALLOW
FOR SOME RECOVERY THOUGH...RANGING FROM THE UPPER 80S NORTHEAST TO
NEAR 90 POSSIBLY LOWER 90S ACROSS OUR FAR SOUTHWEST. THIS WILL
RESULT IN ML CAPES IN THE 1500 TO POSSIBLY AS HIGH 2500 J/KG
RANGE LATE THIS AFTERNOON...WITH A SOUTHWEST TO NORTHEAST GRADIENT
ACROSS OUR AREA. BIG QUESTION IS TRACK/TIMING/INTENSITY OF
SECONDARY REMNANT MCS NOW PUSHING DOWN INTO NORTHERN MI. LATEST
NAM/RAP SUGGESTING THE BEST ACTIVITY ASSOCIATED WITH THIS WILL
REMAIN MORE OFF TO OUR NORTHEAST WHILE THE LATEST HRRR IS
INDICATING IT MAY TRACK A LITTLE FARTHER WEST LATE THIS AFTERNOON.
THINK BEST GUESS WOULD BE THAT IT WILL TRACK DOWN ALONG THE
NORTHEAST EDGE OF THE BETTER INSTABILITY GRADIENT...WHICH WOULD
ALLOW FOR IT TO AFFECT AT LEAST OUR NORTHEASTERN AREAS. AS A
RESULT...WILL BUMP UP POPS ACROSS ABOUT THE NORTHEAST THIRD OF
OUR FA...BUT STILL KEEP THEM IN THE HIGH CHANCE CATEGORY DUE TO
THE UNCERTAINTY. BEST DEEP AND MID LAYER SHEAR WILL ALSO REMAIN
ALONG AND NORTHEAST OF OUR FA LATER TODAY SO EXPECT BEST CHANCE
FOR ANY SEVERE STORMS THROUGH THIS AFTERNOON TO BE ACROSS OUR
NORTHEASTERN. THE PRIMARY SEVERE THREAT WOULD BE DAMAGING WINDS
AND POSSIBLY LARGE HAIL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
IF IT WAS NOT STATED IN THE NEAR TERM...MODELS ARE NOT HANDLING
THE ONGOING WEATHER WELL AND DIFFER VASTLY IN THEIR INTERPRETATION
OF THE STATE OF THE WEATHER IN THE SHORT TERM. THE HIGH
TEMPERATURES REACHING INTO THE 90S AND INCREASED MOISTURE THROUGH
THE PERIOD WILL LEAD TO INCREASED THREAT FOR STORMS...ESPECIALLY
ON WEDNESDAY AS A FAIRLY PREDICTABLE COLD FRONT WORKS THROUGH THE
OHIO VALLEY AND SPARKS CONVECTIVE ACTIVITY.
THE LIKELY CHANCES OF STORMS IN THE LATE AFTERNOON AND EVENING
WERE NOT AS CUT AND DRY AS I WOULD PREFER TO CARRY SO POPS WERE
LOWERED FOR THIS TIME TO JUST CHANCE. THE BETTER CHANCE FOR
SHOWERS ON WEDNESDAY WILL OCCUR IN THE NORTHEAST BUT COULD BE
COMPROMISED BY CLOUD COVER LIMITING THE SURFACE BASED INSTABILITY
THAT WILL BE NECESSARY FOR STORMS TO PROGRESS. THIS CLOUD COVER
WILL ALSO PUT THE DAYS HIGH TEMPERATURES IN QUESTION WHERE THE
FORECAST UPPER 80S COULD BE 5 DEGREES TOO HIGH OR SO.
DRIER AIR IN THE WAKE OF THE COLD FRONT WILL BE THE DIFFERENCE IN
THE AIRMASS...NOT NECESSARILY COLDER TEMPERATURES.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
NUMERICAL MODEL SOLNS SHOWING WEAK PERTURBATIONS DROPPING SE
AROUND THE PERIPHERY OF THE MID LEVEL RIDGE. THEREFORE...CAN NOT
RULE OUT VERY LOW POP/ISOLD SHOWERS/THUNDERSTORMS TOWARD THE END
OF THE WEEK INTO NEXT WEEKEND. THESE FEATURES ARE WEAK AND
DIFFICULT TO TIME...AND WITH PROB BEING SO LOW WILL MAINTAIN DRY
FCST THRU FRIDAY NIGHT AND THEN ONLY ALLOW A SLIGHT CHANCE MAINLY
ACROSS THE WEST SATURDAY AFTN. ON SUNDAY A LITTLE MORE SIGNIFICANT
S/W MAY LEAD TO PRECIPITATION. WILL CONTINUE TO LIMIT POPS TO
CHANCE CATEGORY WITH THIS FEATURE. TEMPERATURES REMAIN CLOSE TO 10
DEGREES ABOVE NORMAL WITH HIGHS SAT/SUN UPPER 80S NE TO LOWER 90S
SW.
DETERMINISTIC NUMERICAL MODEL SOLNS HAVE BEEN DIFFERING ON HOW MUCH
THE MID/UPR LEVEL RIDGE PUSHES BACK EAST INTO THE OHIO VALLEY. 00Z
GFS BEING MORE AGGRESSIVE WITH THE RIDGE THAN THE ECMWF AND WAS
HOLDING THE SFC FRONT TO OUR NORTH...WHILE ECMWF WAS PUSHING THE
FRONT THRU ON MONDAY. 12Z DETERMINISTIC GFS RUN HAS TRENDED MORE
TOWARD THE ECMWF...SO WILL ALLOW FOR AN INCREASE IN POPS DURG THE
DAY MONDAY TO ACCOUNT FOR THIS FRONT. TEMPERATURES SLIGHTLY COOLER
MONDAY WITH HIGHS RANGING FROM MID 80S NORTH TO UPPER 80S SOUTH.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
SHRA THAT HAD BEEN DROPPING S TOWARDS KCMH/KLCK EARLY THIS MORNING HAS
SLIPPED TO THE EAST WHILE IT WEAKENED. ADDITIONAL CONVECTION
CONTINUES TO DEVELOP OVER MI AND NW OH. EXPECT THIS CONVECTION TO
DROP SE TODAY AS THE ERN EDGE OF THE H5 RIDGE BREAKS DOWN.
LATEST RUNS OF ALL MODELS TRY AND KEEP THE MAJORITY OF THE PCPN E
OF THE TAFS. THE 00Z NAM IS AN OUTLIER AS IT IS AGGRESSIVE IN
REDEVELOPING CONVECTION ACROSS THE REGION TODAY. BASED ON THE
LATEST RADAR LOOP...IT LOOKS LIKE THE MODELS MAY BE TOO FAR E THIS
AFTN. SO WENT WITH A VCTS AT KCMH/KLCK BEGINNING AT 16Z AND BUILT
THE SCT CONVECTION WWD INTO KILN BY 18Z. KEPT THE WRN TAFS DRY
ATTM.
OVERNIGHT TONIGHT NW FLOW CONTINUES...AS A BACKDOOR CDFNT DROPS
TOWARDS THE REGION. COULD SEE SOME SCT CONVECTION OVERNIGHT. THE
CHC LOOKS LOW ENUF TO KEEP KCVG/KLUK DRY OVERNIGHT.
OUTLOOK...THUNDERSTORMS POSSIBLE WEDNESDAY INTO WEDNESDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...JGL
SHORT TERM...FRANKS
LONG TERM...AR
AVIATION...SITES
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
801 AM EDT TUE AUG 27 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHEASTERN STATES WILL REMAIN IN PLACE
THROUGH MIDWEEK. LOW PRESSURE WILL MOVE EAST ACROSS THE LOWER
GREAT LAKES TONIGHT AND DRAG A WEAK COLD FRONT SOUTH THROUGH THE
AREA ON WEDNESDAY. HIGH PRESSURE WILL RETURN TO THE AREA TOWARD
THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...BASED ON RADAR TRENDS WAS ABLE TO MAKE SIGNIFICANT
CHANGES TO POPS. HAVE A HIGH DEGREE OF CONFIDENCE THAT THE
REMNANTS FROM THE MCS WILL DROP ACROSS MUCH OF THE AREA THROUGH
THE MORNING HOURS. ALSO SHOWERS/THUNDERSTORMS HAVE DEVELOPED
AHEAD OF THE MAIN CONVECTION IN THE KCLE AREA AND OVER THE LAKE AS
WELL AS FAR NWRN OHIO. BOOSTED POPS TO NEAR 100 PERCENT MUCH OF
THE AREA FOR AT LEAST THE MORNING. STILL THINKING WE GET A
RELATIVE BREAK THIS AFTERNOON...BUT STILL A CHANCE...AHEAD OF
ANOTHER ROUND TONIGHT.
ORIGINAL...WIDELY SCATTERED SHOWERS ACROSS THE AREA EARLY THIS
MORNING BUT MOSTLY WEST FROM FDY AREA TO MNN MOVING SOUTH. MAIN
ISSUE FOR TODAY WILL BE THE MCS MOVING SOUTHEAST THROUGH WI.
CIRRUS WILL MOVE INTO NWRN OHIO BY 4 TO 5AM WILL HRRR BRINGING
DYING COMPLEX INTO THE AREA 12-15Z. BROUGHT LIKELY POPS TO THE
AREA FROM KCLE TO KTOL BY 15Z WITH CHANCE POPS ELSEWHERE.
INCREASED POPS TO LIKELY SOUTHEAST AS SYSTEM DROPS SOUTHEAST
THROUGH THE AREA. THROUGH THE AFTERNOON DROPPED POPS BACK TO
CHANCE.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
TONIGHT FOLLOWED SREF/NAM BLEND WHICH SHOWS A DEVELOPING OR
POSSIBLY ONGOING CONVECTIVE SYSTEM TO OUR NORTHWEST THAT WILL DROP
ACROSS THE AREA THROUGH THE EVENING AND EARLY OVERNIGHT HOURS.
WENT A BIT AGGRESSIVE ON POPS WITH CATEGORICAL POPS ACROSS A LARGE
PORTION OF THE AREA. WILL CONTINUE THIS INTO EARLY WEDNESDAY AS A
WEAK COLD FRONT DROPS THROUGH THE AREA BEFORE DROPPING BACK TO
LIKELY/CHANCE DURING THE AFTERNOON. WEDNESDAY NIGHT AND THURSDAY
DRIER MORE STABLE AIR MOVES IN FROM THE NORTH BEHIND THE COLD
FRONT. CONTINUE DRY THURSDAY NIGHT. FRIDAY PUT IN A SLIGHT CHANCE
WHICH WILL OF COURSE NOT SHOW UP IN THE TEXT. A BIT CONCERNED
ABOUT INCREASING MOISTURE FROM THE NORTHWEST WITH A SHORT WAVE
SHOWING UP IN THE NWLY FLOW ALOFT. INCREASED POPS TO CHANCE NRN
FRINGE FRIDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE AT THE SURFACE WILL BUILD TO THE EAST COAST BY
SATURDAY ALLOWING MOISTURE TO START TO CREEP BACK NORTH INTO THE
REGION WITH A LIGHT SOUTHERLY RETURN FLOW DEVELOPING. THE WESTERN
HALF OF THE FORECAST AREA WILL SEE AT LEAST A CHANCE OF
THUNDERSTORMS WITH SOME INSTABILITY AND SHORTWAVE ENERGY CONTINUING
TO ROUND THE UPPER LEVEL RIDGE. MODELS ARE IN FAIR AGREEMENT WITH
THE 00Z CYCLE IN SHOWING A STRONGER TROUGH ATTEMPTING TO DAMPEN THE
RIDGE OVER THE GREAT LAKES ON SUNDAY WHICH SHOULD YIELD BETTER
CHANCES OF SHOWERS AND THUNDERSTORMS. CONFIDENCE IS LOW IN TIMING
AND PATTERN EVOLUTION THAT FAR OUT SO WILL JUST CARRY A 30 POP FOR
NOW. TEMPERATURES WILL BE ABOVE NORMAL OVER THE WEEKEND WITH A
COOLING TREND FOR EARLY NEXT WEEK AS A COLD FRONT PUSHES SOUTH
ACROSS THE AREA.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
SCATTERED SHOWERS AND THUNDERSTORMS ARE DEVELOPING IN THE CLEVELAND
VICINITY AHEAD OF A LARGER COMPLEX OF SHOWERS AND THUNDERSTORMS
MOVING SOUTHEAST OUT OF MICHIGAN. THIS COMPLEX WILL MOVE SOUTHEAST
ACROSS THE AREA THROUGH ABOUT 15Z WITH AN AREA OF RAIN LINGERING FOR
A COUPLE MORE HOURS BEHIND IT. SOME SITES WILL GUST TO 25-30 KNOTS
WITH THE THUNDERSTORMS.
THIS WILL HELP TO STABILIZE THE AREA FOR A PERIOD OF TIME THIS
AFTERNOON. IT IS SOMEWHAT UNCERTAIN IF THUNDERSTORMS WILL RE-DEVELOP
THIS AFTERNOON AND WILL DEPEND ON THE DEGREE OF CLEARING AND
LINGERING OUTFLOW BOUNDARIES. BEST CHANCES WILL BE IN NW OHIO AFTER
21Z. LOW PRESSURE WILL MOVE THROUGH THE SOUTHERN GREAT LAKES
REGION TONIGHT BRINGING ANOTHER COMPLEX OF SHOWERS AND
THUNDERSTORMS AFTER 04Z. SOME THUNDERSTORMS MAY BE STRONG WITH
HEAVY RAIN OVERNIGHT.
OUTLOOK...MVFR POSSIBLE IN SHOWERS WEDNESDAY MORNING.
&&
.MARINE...
WINDS ON LAKE ERIE WILL MAINTAIN A WESTERLY COMPONENT AT 15 KNOTS OR
LESS TODAY. MULTIPLE ROUNDS OF THUNDERSTORMS ARE POSSIBLE ON THE
LAKE OVER THE NEXT 24 HOURS...ESPECIALLY TONIGHT AS A WAVE OF LOW
PRESSURE MOVES THROUGH THE SOUTHERN GREAT LAKES. THE AREA IS IN A
SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH TONIGHT. THIS SYSTEM
WILL PULL A COLD FRONT SOUTH ACROSS THE LAKE BEHIND IT ON WEDNESDAY
WITH WINDS SHIFTING TO THE NORTH AT 10-15 KNOTS INTO THURSDAY.
THE NORTHERLY FLOW WILL RESULT IN SOME INCREASE IN WAVE CONDITIONS
IN THE NEARSHORE WATERS AS WAVES BUILD TO 1 TO 3 FEET ON THURSDAY.
HIGH PRESSURE WILL LIGHT WINDS AND WAVES WILL RETURN ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
625 AM EDT TUE AUG 27 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHEASTERN STATES WILL REMAIN IN PLACE
THROUGH MIDWEEK. LOW PRESSURE WILL MOVE EAST ACROSS THE LOWER
GREAT LAKES TONIGHT AND DRAG A WEAK COLD FRONT SOUTH THROUGH THE
AREA ON WEDNESDAY. HIGH PRESSURE WILL RETURN TO THE AREA TOWARD
THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...BASED ON RADAR TRENDS WAS ABLE TO MAKE SIGNIFICANT
CHANGES TO POPS. HAVE A HIGH DEGREE OF CONFIDENCE THAT THE
REMNANTS FROM THE MCS WILL DROP ACROSS MUCH OF THE AREA THROUGH
THE MORNING HOURS. ALSO SHOWERS/THUNDERSTORMS HAVE DEVELOPED
AHEAD OF THE MAIN CONVECTION IN THE KCLE AREA AND OVER THE LAKE AS
WELL AS FAR NWRN OHIO. BOOSTED POPS TO NEAR 100 PERCENT MUCH OF
THE AREA FOR AT LEAST THE MORNING. STILL THINKING WE GET A
RELATIVE BREAK THIS AFTERNOON...BUT STILL A CHANCE...AHEAD OF
ANOTHER ROUND TONIGHT.
ORIGINAL...WIDELY SCATTERED SHOWERS ACROSS THE AREA EARLY THIS
MORNING BUT MOSTLY WEST FROM FDY AREA TO MNN MOVING SOUTH. MAIN
ISSUE FOR TODAY WILL BE THE MCS MOVING SOUTHEAST THROUGH WI.
CIRRUS WILL MOVE INTO NWRN OHIO BY 4 TO 5AM WILL HRRR BRINGING
DYING COMPLEX INTO THE AREA 12-15Z. BROUGHT LIKELY POPS TO THE
AREA FROM KCLE TO KTOL BY 15Z WITH CHANCE POPS ELSEWHERE.
INCREASED POPS TO LIKELY SOUTHEAST AS SYSTEM DROPS SOUTHEAST
THROUGH THE AREA. THROUGH THE AFTERNOON DROPPED POPS BACK TO
CHANCE.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
TONIGHT FOLLOWED SREF/NAM BLEND WHICH SHOWS A DEVELOPING OR
POSSIBLY ONGOING CONVECTIVE SYSTEM TO OUR NORTHWEST THAT WILL DROP
ACROSS THE AREA THROUGH THE EVENING AND EARLY OVERNIGHT HOURS.
WENT A BIT AGGRESSIVE ON POPS WITH CATEGORICAL POPS ACROSS A LARGE
PORTION OF THE AREA. WILL CONTINUE THIS INTO EARLY WEDNESDAY AS A
WEAK COLD FRONT DROPS THROUGH THE AREA BEFORE DROPPING BACK TO
LIKELY/CHANCE DURING THE AFTERNOON. WEDNESDAY NIGHT AND THURSDAY
DRIER MORE STABLE AIR MOVES IN FROM THE NORTH BEHIND THE COLD
FRONT. CONTINUE DRY THURSDAY NIGHT. FRIDAY PUT IN A SLIGHT CHANCE
WHICH WILL OF COURSE NOT SHOW UP IN THE TEXT. A BIT CONCERNED
ABOUT INCREASING MOISTURE FROM THE NORTHWEST WITH A SHORT WAVE
SHOWING UP IN THE NWLY FLOW ALOFT. INCREASED POPS TO CHANCE NRN
FRINGE FRIDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE AT THE SURFACE WILL BUILD TO THE EAST COAST BY
SATURDAY ALLOWING MOISTURE TO START TO CREEP BACK NORTH INTO THE
REGION WITH A LIGHT SOUTHERLY RETURN FLOW DEVELOPING. THE WESTERN
HALF OF THE FORECAST AREA WILL SEE AT LEAST A CHANCE OF
THUNDERSTORMS WITH SOME INSTABILITY AND SHORTWAVE ENERGY CONTINUING
TO ROUND THE UPPER LEVEL RIDGE. MODELS ARE IN FAIR AGREEMENT WITH
THE 00Z CYCLE IN SHOWING A STRONGER TROUGH ATTEMPTING TO DAMPEN THE
RIDGE OVER THE GREAT LAKES ON SUNDAY WHICH SHOULD YIELD BETTER
CHANCES OF SHOWERS AND THUNDERSTORMS. CONFIDENCE IS LOW IN TIMING
AND PATTERN EVOLUTION THAT FAR OUT SO WILL JUST CARRY A 30 POP FOR
NOW. TEMPERATURES WILL BE ABOVE NORMAL OVER THE WEEKEND WITH A
COOLING TREND FOR EARLY NEXT WEEK AS A COLD FRONT PUSHES SOUTH
ACROSS THE AREA.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY
AS THE ATMOSPHERE CONTINUES TO MOISTEN. EARLY MORNING HZ/BR ALSO
POSSIBLE 09-13Z WITH INCREASING DEWPOINTS. EARLY THIS MORNING WE
ARE WATCHING A COMPLEX OF THUNDERSTORMS OVER NE WISCONSIN WHICH
WILL TAKE AIM AT NRN OHIO AFTER 12Z. EXPECTING THIS COMPLEX TO
UNDERGO SOME WEAKENING AS IT APPROACHES. REMNANTS OF THIS FEATURE
WILL RESULT IN ADDITIONAL STORM DEVELOPMENT EARLY THIS AFTERNOON
AND HAVE INCLUDED A VCTS IN ALL SITES. TIMING REMAINS IN QUESTION
BUT EXPECT PRETTY GOOD CHANCES FOR A THUNDERSTORM AT SOME POINT
THIS AFTERNOON...ESPECIALLY AT CLE/MFD/CAK/YNG WITH THE POTENTIAL
FOR SOME THUNDERSTORMS TO BE STRONG TO SEVERE.
MODELS ARE IN PRETTY GOOD AGREEMENT THAT WE ARE LOOKING FOR ANOTHER
ROUND OF THUNDERSTORMS TOWARDS THE END OF THE TAF CYCLE (04-12Z) AS
LOW PRESSURE TRACKS THROUGH THE SOUTHERN GREAT LAKES. THESE
THUNDERSTORMS COULD ONCE AGAIN BE STRONG WITH HEAVY RAINFALL
POSSIBLE.
OUTLOOK...MVFR PROBABLE WITH SHRA/TSRA BR TUESDAY AFTERNOON THROUGH
WEDNESDAY.
&&
.MARINE...
WINDS ON LAKE ERIE WILL MAINTAIN A WESTERLY COMPONENT AT 15 KNOTS OR
LESS TODAY. MULTIPLE ROUNDS OF THUNDERSTORMS ARE POSSIBLE ON THE
LAKE OVER THE NEXT 24 HOURS...ESPECIALLY TONIGHT AS A WAVE OF LOW
PRESSURE MOVES THROUGH THE SOUTHERN GREAT LAKES. THE AREA IS IN A
SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH TONIGHT. THIS SYSTEM
WILL PULL A COLD FRONT SOUTH ACROSS THE LAKE BEHIND IT ON WEDNESDAY
WITH WINDS SHIFTING TO THE NORTH AT 10-15 KNOTS INTO THURSDAY.
THE NORTHERLY FLOW WILL RESULT IN SOME INCREASE IN WAVE CONDITIONS
IN THE NEARSHORE WATERS AS WAVES BUILD TO 1 TO 3 FEET ON THURSDAY.
HIGH PRESSURE WILL LIGHT WINDS AND WAVES WILL RETURN ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
552 AM EDT TUE AUG 27 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHEASTERN STATES WILL REMAIN IN PLACE
THROUGH MIDWEEK. LOW PRESSURE WILL MOVE EAST ACROSS THE LOWER
GREAT LAKES TONIGHT AND DRAG A WEAK COLD FRONT SOUTH THROUGH THE
AREA ON WEDNESDAY. HIGH PRESSURE WILL RETURN TO THE AREA TOWARD
THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
WIDELY SCATTERED SHOWERS ACROSS THE AREA EARLY THIS MORNING BUT
MOSTLY WEST FROM FDY AREA TO MNN MOVING SOUTH. MAIN ISSUE FOR
TODAY WILL BE THE MCS MOVING SOUTHEAST THROUGH WI. CIRRUS WILL
MOVE INTO NWRN OHIO BY 4 TO 5AM WILL HRRR BRINGING DYING COMPLEX
INTO THE AREA 12-15Z. BROUGHT LIKELY POPS TO THE AREA FROM KCLE TO
KTOL BY 15Z WITH CHANCE POPS ELSEWHERE. INCREASED POPS TO LIKELY
SOUTHEAST AS SYSTEM DROPS SOUTHEAST THROUGH THE AREA. THROUGH THE
AFTERNOON DROPPED POPS BACK TO CHANCE.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
TONIGHT FOLLOWED SREF/NAM BLEND WHICH SHOWS A DEVELOPING OR
POSSIBLY ONGOING CONVECTIVE SYSTEM TO OUR NORTHWEST THAT WILL DROP
ACROSS THE AREA THROUGH THE EVENING AND EARLY OVERNIGHT HOURS.
WENT A BIT AGGRESSIVE ON POPS WITH CATEGORICAL POPS ACROSS A LARGE
PORTION OF THE AREA. WILL CONTINUE THIS INTO EARLY WEDNESDAY AS A
WEAK COLD FRONT DROPS THROUGH THE AREA BEFORE DROPPING BACK TO
LIKELY/CHANCE DURING THE AFTERNOON. WEDNESDAY NIGHT AND THURSDAY
DRIER MORE STABLE AIR MOVES IN FROM THE NORTH BEHIND THE COLD
FRONT. CONTINUE DRY THURSDAY NIGHT. FRIDAY PUT IN A SLIGHT CHANCE
WHICH WILL OF COURSE NOT SHOW UP IN THE TEXT. A BIT CONCERNED
ABOUT INCREASING MOISTURE FROM THE NORTHWEST WITH A SHORT WAVE
SHOWING UP IN THE NWLY FLOW ALOFT. INCREASED POPS TO CHANCE NRN
FRINGE FRIDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE AT THE SURFACE WILL BUILD TO THE EAST COAST BY
SATURDAY ALLOWING MOISTURE TO START TO CREEP BACK NORTH INTO THE
REGION WITH A LIGHT SOUTHERLY RETURN FLOW DEVELOPING. THE WESTERN
HALF OF THE FORECAST AREA WILL SEE AT LEAST A CHANCE OF
THUNDERSTORMS WITH SOME INSTABILITY AND SHORTWAVE ENERGY CONTINUING
TO ROUND THE UPPER LEVEL RIDGE. MODELS ARE IN FAIR AGREEMENT WITH
THE 00Z CYCLE IN SHOWING A STRONGER TROUGH ATTEMPTING TO DAMPEN THE
RIDGE OVER THE GREAT LAKES ON SUNDAY WHICH SHOULD YIELD BETTER
CHANCES OF SHOWERS AND THUNDERSTORMS. CONFIDENCE IS LOW IN TIMING
AND PATTERN EVOLUTION THAT FAR OUT SO WILL JUST CARRY A 30 POP FOR
NOW. TEMPERATURES WILL BE ABOVE NORMAL OVER THE WEEKEND WITH A
COOLING TREND FOR EARLY NEXT WEEK AS A COLD FRONT PUSHES SOUTH
ACROSS THE AREA.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY
AS THE ATMOSPHERE CONTINUES TO MOISTEN. EARLY MORNING HZ/BR ALSO
POSSIBLE 09-13Z WITH INCREASING DEWPOINTS. EARLY THIS MORNING WE
ARE WATCHING A COMPLEX OF THUNDERSTORMS OVER NE WISCONSIN WHICH
WILL TAKE AIM AT NRN OHIO AFTER 12Z. EXPECTING THIS COMPLEX TO
UNDERGO SOME WEAKENING AS IT APPROACHES. REMNANTS OF THIS FEATURE
WILL RESULT IN ADDITIONAL STORM DEVELOPMENT EARLY THIS AFTERNOON
AND HAVE INCLUDED A VCTS IN ALL SITES. TIMING REMAINS IN QUESTION
BUT EXPECT PRETTY GOOD CHANCES FOR A THUNDERSTORM AT SOME POINT
THIS AFTERNOON...ESPECIALLY AT CLE/MFD/CAK/YNG WITH THE POTENTIAL
FOR SOME THUNDERSTORMS TO BE STRONG TO SEVERE.
MODELS ARE IN PRETTY GOOD AGREEMENT THAT WE ARE LOOKING FOR ANOTHER
ROUND OF THUNDERSTORMS TOWARDS THE END OF THE TAF CYCLE (04-12Z) AS
LOW PRESSURE TRACKS THROUGH THE SOUTHERN GREAT LAKES. THESE
THUNDERSTORMS COULD ONCE AGAIN BE STRONG WITH HEAVY RAINFALL
POSSIBLE.
OUTLOOK...MVFR PROBABLE WITH SHRA/TSRA BR TUESDAY AFTERNOON THROUGH
WEDNESDAY.
&&
.MARINE...
WINDS ON LAKE ERIE WILL MAINTAIN A WESTERLY COMPONENT AT 15 KNOTS OR
LESS TODAY. MULTIPLE ROUNDS OF THUNDERSTORMS ARE POSSIBLE ON THE
LAKE OVER THE NEXT 24 HOURS...ESPECIALLY TONIGHT AS A WAVE OF LOW
PRESSURE MOVES THROUGH THE SOUTHERN GREAT LAKES. THE AREA IS IN A
SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH TONIGHT. THIS SYSTEM
WILL PULL A COLD FRONT SOUTH ACROSS THE LAKE BEHIND IT ON WEDNESDAY
WITH WINDS SHIFTING TO THE NORTH AT 10-15 KNOTS INTO THURSDAY.
THE NORTHERLY FLOW WILL RESULT IN SOME INCREASE IN WAVE CONDITIONS
IN THE NEARSHORE WATERS AS WAVES BUILD TO 1 TO 3 FEET ON THURSDAY.
HIGH PRESSURE WILL LIGHT WINDS AND WAVES WILL RETURN ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
401 AM EDT TUE AUG 27 2013
.SYNOPSIS...
WEAK SHORTWAVES CROSSES TODAY...UNDER NORTHWEST FLOW ALOFT. COLD
FRONT CROSSES WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE VISITS
BRIEFLY FRIDAY BEFORE PATTERN REPEATS.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH LEVEL CLOUDS ASSOCIATED WITH A DYING MCS ACROSS LAKE MICHIGAN
WILL COVER THE AREA THIS MORNING. NORTHWEST FLOW ALOFT...AND
EMBEDDED SHORTWAVES ARE EVIDENT IN VORT MAX FIELD ON H5 CHARTS.
ALTHOUGH IT LOOKS LIKE CONVECTIVE FEEDBACK...PIECES OF ENERGY
LOOKS REAL ACTING AS FORCING MECHANISMS.
THE HRRR MODEL BRINGS REMNANTS OF GREAT LAKES MCS OVER CKB...EKN
AND NORTHEAST MOUNTAINS THIS AFTERNOON. ANOTHER SHORTWAVE IS
EVIDENT IN H5 CHARTS APPROACHING THE AREA FROM THE NORTHWEST
WEDNESDAY.
NAM AND RUC MODELS SUGGEST AFTERNOON AND EVENING CONVECTION IN QPF
AND SFC CAPE FIELDS ALTHOUGH THE LATER LOOKS OVERDONE BY THE NAM
WITH DEWPOINTS IN THE LOW TO MID 70S. AN AREA OF DEEP LAYERED
SHEAR MOVES INTO SOUTHEAST OH AND PORTIONS OF WV THIS AFTERNOON.
EXPECT CONVECTIVE INITIATION WITH FEW STORMS BUT DO NOT EXPECT
THEM TO BECOME SEVERE.
CODED SKY AND POP GRIDS PER LATEST SATELLITE AND RADAR IMAGES. MID
LEVEL CLOUDS ADVECTING FROM THE NORTHWEST ACROSS SOUTHEAST OHIO
SITES SUCH AS PKB AND HTS EARLY THIS MORNING.
USED THE CONS MOS FOR TEMPERATURE THROUGH THE PERIOD.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
ACTIVE WEATHER MAINLY THE FIRST HALF OF THE SHORT TERM PERIOD...WITH
PRECIP CHANCES AND POSSIBLE SUBSEQUENT HYDRO ISSUES PRIMARILY WED
AND WED NIGHT.
WEDNESDAY...AREA REMAINS UNDER NORTHWEST FLOW ALOFT WHILE AT THE SFC
SOUTHWEST WINDS IN PLACE. THOUGH DIFFS EXIST WITH STRENGTH AND
PLACEMENT...CONSENSUS OF NWP OUTPUT IS IN FAIRLY DECENT AGREEMENT
DRAGGING A COUPLE OF VORT MAXES ACROSS THE NORTHEASTERN ZONES FROM
NW TO SE ON WED. FIRST RIPPLE PUSHES INTO THE AREA RIGHT AROUND 12Z
WED AND OVER THE CENTRAL PART OF THE AREA BY 18Z WED. APPEARS THE
BEST OVERALL MOISTURE DEPTH NOT REALLY CO-LOCATED WITH BEST OVERALL
FORCING INITIALLY...WITH THE BEST MOISTURE OVER THE NE ZONES AND
BETTER DYNAMIC FORCING STILL TO THE WEST AND NORTHWEST AT 12Z WED.
HOWEVER OMEGA FIELDS INDICATE AMPLE LIFT THROUGH A DEEP LAYER ACROSS
THE NE ZONES AND WITH PLENTY OF MOISTURE IN PLACE WILL CONTINUE
CATEGORICAL POPS NE ZONES AT THE OUTSET. EXPECT SHOWERS AND
THUNDERSTORMS TO QUICKLY RAMP UP ACROSS THE NORTH AND NW ZONES AS
WELL DURING THE MORNING HOURS WITH THE APPROACH OF THE
AFOREMENTIONED VORT MAX AND ITS ASSOC LIFT...AS WELL AS LARGE SCALE
FORCING FOR ASCENT. BY THE AFTERNOON HOURS THE NEXT VORT MAX ON
NORTHWEST FLOW ALOFT PUSHES INTO THE NW ZONES BY 00Z THU. MODELS
STILL DIFFER ON THE PLACEMENT OF THE ASSOC SFC LOW...ALTHOUGH THEY
ARE TRYING TO COME CLOSER TOGETHER. STILL...LATEST NAM DEPICTS SFC
LOW STILL WELL WEST NEAR CINCINNATI AT 00Z THU WHILE OP GUIDANCE HAS
IT FURTHER EAST/NORTHEAST IN THE AREA OF OUR SE OHIO ZONES. GEFS
MEAN AND ITS MEMBERS SUPPORT THE FURTHER EAST SOLN AS DOES THE SREF
MEAN AND THUS WILL LEAN THE FORECAST IN THIS DIRECTION...WITH THE
LOW AND FRONT ENTERING INTO NW ZONES BY 00Z THU. ALL IN ALL WILL
CONTINUE TO TREND HIGHEST POPS FROM THE NE ZONES TOWARDS THE CENTRAL
AND SOUTHERN ZONES BY 00Z THU. EXPANDED THE COVERAGE OF CATEGORICAL
POPS TO INCLUDE GENERALLY LOCATIONS ALONG AND NORTHEAST OF A
BKW-CRW-PERRY COUNTY OH LINE AS IN THE END MOST IF NOT ALL OF THOSE
LOCATIONS SHOULD SEE SOME MEASURABLE RAINFALL BY DAY/S END ON
WEDNESDAY...THOUGH PINPOINTING THE TIMING ISN/T QUITE SO
STRAIGHTFORWARD. QPF AMOUNTS STILL RUNNING AROUND 0.75IN TO
1.00IN...AND WITH 3-HR FFG GUIDANCE AROUND 2 INCHES THERE IS CONCERN
FOR THE POSSIBILITY OF FLASH FLOODING. STILL NOT QUITE ENOUGH
CONFIDENCE TO ISSUE A WATCH AT THIS POINT AND WILL LET THE DAYSHIFT
TAKE ONE MORE LOOK AT IT. WILL CONTINUE HYDRO CONCERN MENTION
HOWEVER IN HWO AND DID GO AHEAD AND INCLUDE HEAVY RAIN WORDING IN
THE WX GRIDS WED.
PRECIP EXPECTED TO COME TO AN END FROM NW TO SE OVERNIGHT WED NIGHT
AS THE FRONT SWEEPS ACROSS THE AREA. MOST LOCATIONS WILL BE DRY ON
THURSDAY WITH THE FRONT WELL EAST OF THE AREA UNDER A PARTLY CLOUDY
SKY AND HIGHS GENERALLY IN THE MID 80S FOR LOWLAND LOCATIONS. WILL
KEEP INHERITED SLIGHT CHANCE AND LOW CHANCE POPS FOR THE
EAST/SOUTHEAST HIGH TERRAIN WITH A DECENT SLUG OF LLVL MOISTURE
REMAINING ALONG WITH SFC CONVERGENCE ON THE RIDGETOPS PROGGED.
THURSDAY NIGHT ALL LOCATIONS SHOULD DRY OUT WITH THE LOSS OF DAYTIME
HEATING. SFC HIGH PRESSURE CONTINUES TO MOVE EASTWARD AWAY FROM THE
AREA WITH RETURN SOUTHEAST FLOW SETTING UP. THIS...ALONG WITH
ANOTHER S/W TROUGH AND ASSOC VORT MAX MOVING INTO THE NORTHERN ZONES
BY AND AFTER 06Z FRI LENDS SOME POTENTIAL FOR LIGHT SHOWER
REDEVELOPMENT ON THE EAST SLOPES TOWARDS THE DAWN HOURS FRIDAY
MORNING. WILL LEAVE FORECAST DRY FOR NOW.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
GENERALLY FOLLOWED HPC IN EXTENDED WHICH WILL FEATURE QUIETER AND
DRIER WX DESPITE CONTINUING NW FLOW ALOFT. TEMPS RUNNING IN MID
80S AND LOWS GENERALLY IN 60S. GUIDANCE CONT TO RUN ON WARM
SIDE...AS HAS BEEN THE CASE MUCH OF THIS SUMMER. THINK WITH WET
GROUNDS THIS SEASON...FELT HEDGING A LITTLE BELOW GUIDANCE WAS
WARRANTED.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS BECOMING MVFR AT MOST PLACES PER BOUNDARY LAYER
FLOW FROM 10-15 KNOTS PREVENTING FOG FORMATION. THE EXCEPTION WILL
BE EKN...AND OTHER PROTECTED VALLEYS WHICH COULD EXPERIENCE DENSE FOG
FOR IFR CONDITIONS FROM 09-12Z.
RADAR IMAGES SHOW A WEAK LINE OF LIGHT SHOWERS MOVING SOUTH ACROSS
SOUTHEAST OH. THESE RAIN ACTIVITY SEEMS TO BE DIMINISHING AND
DYING WHILE WEAKLY REDEVELOP ALONG A DEFORMATION ZONE. DO NOT
EXPECT MUCH IMPACT WITH THIS FEATURE. AN ASSOCIATED LOW TO MID
STRATUS DECK WITH LIGHT RAIN SHOWERS COULD PROVIDE BRIEF PERIODS
OF MVFR/IFR ALONG THROUGH 09-12Z MAINLY HTS AND PKB.
RECOGNIZE NORTHWEST FLOW AND EMBEDDED SHORTWAVES AT H5 PATTERN
TODAY. EXPECT SERIES OF THUNDERSTORM COMPLEXES DEVELOPING AND
SPREADING SOUTHEAST DURING THE AFTERNOON AND EVENING PERIODS.
INCLUDED VCTS AT THE END OF TAF.
BKW REMAINS AMD NOT SKED ON ACCOUNT OF COMMUNICATION ISSUES.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: TIMING AND COVERAGE OF CONVECTION COULD VARY
THIS AFTERNOON AND EVENING.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 08/27/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY L L L L L H M M H H H H
HTS CONSISTENCY L L L L L M H H H H H H
BKW CONSISTENCY M M M M M H H M M M M M
EKN CONSISTENCY L L L L L H H M M H H H
PKB CONSISTENCY L L L L L H H H H H M H
CKB CONSISTENCY L L L L L M H H H H M H
AFTER 06Z WEDNESDAY...
IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS TUESDAY AND WEDNESDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...KMC/30
NEAR TERM...ARJ
SHORT TERM...30
LONG TERM...30
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
333 AM EDT TUE AUG 27 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE SOUTHEASTERN STATES THE FIRST
HALF OF THE WEEK. MEANWHILE A WEAK FRONT WILL SAG SOUTH ACROSS
THE EASTERN GREAT LAKES THIS EVENING. AN AREA OF LOW PRESSURE
WILL MOVE EAST ACROSS THE LAKES ON TUESDAY NIGHT AND DRAG A COLD
FRONT SOUTH ACROSS THE AREA ON WEDNESDAY. HIGH PRESSURE WILL
RETURN TO THE AREA FOR THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
WIDELY SCATTERED SHOWERS ACROSS THE AREA EARLY THIS MORNING BUT
MOSTLY WEST FROM FDY AREA TO MNN MOVING SOUTH. MAIN ISSUE FOR
TODAY WILL BE THE MCS MOVING SOUTHEAST THROUGH WI. CIRRUS WILL
MOVE INTO NWRN OHIO BY 4 TO 5AM WILL HRRR BRINGING DYING COMPLEX
INTO THE AREA 12-15Z. BROUGHT LIKELY POPS TO THE AREA FROM KCLE TO
KTOL BY 15Z WITH CHANCE POPS ELSEWHERE. INCREASED POPS TO LIKELY
SOUTHEAST AS SYSTEM DROPS SOUTHEAST THROUGH THE AREA. THROUGH THE
AFTERNOON DROPPED POPS BACK TO CHANCE.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
TONIGHT FOLLOWED SREF/NAM BLEND WHICH SHOWS A DEVELOPING OR
POSSIBLY ONGOING CONVECTIVE SYSTEM TO OUR NORTHWEST THAT WILL DROP
ACROSS THE AREA THROUGH THE EVENING AND EARLY OVERNIGHT HOURS.
WENT A BIT AGGRESSIVE ON POPS WITH CATEGORICAL POPS ACROSS A LARGE
PORTION OF THE AREA. WILL CONTINUE THIS INTO EARLY WEDNESDAY AS A
WEAK COLD FRONT DROPS THROUGH THE AREA BEFORE DROPPING BACK TO
LIKELY/CHANCE DURING THE AFTERNOON. WEDNESDAY NIGHT AND THURSDAY
DRIER MORE STABLE AIR MOVES IN FROM THE NORTH BEHIND THE COLD
FRONT. CONTINUE DRY THURSDAY NIGHT. FRIDAY PUT IN A SLIGHT CHANCE
WHICH WILL OF COURSE NOT SHOW UP IN THE TEXT. A BIT CONCERNED
ABOUT INCREASING MOISTURE FROM THE NORTHWEST WITH A SHORT WAVE
SHOWING UP IN THE NWLY FLOW ALOFT. INCREASED POPS TO CHANCE NRN
FRINGE FRIDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HIGH PRESSURE AT THE SURFACE WILL BUILD TO THE EAST COAST BY
SATURDAY ALLOWING MOISTURE TO START TO CREEP BACK NORTH INTO THE
REGION WITH A LIGHT SOUTHERLY RETURN FLOW DEVELOPING. THE WESTERN
HALF OF THE FORECAST AREA WILL SEE AT LEAST A CHANCE OF
THUNDERSTORMS WITH SOME INSTABILITY AND SHORTWAVE ENERGY CONTINUING
TO ROUND THE UPPER LEVEL RIDGE. MODELS ARE IN FAIR AGREEMENT WITH
THE 00Z CYCLE IN SHOWING A STRONGER TROUGH ATTEMPTING TO DAMPEN THE
RIDGE OVER THE GREAT LAKES ON SUNDAY WHICH SHOULD YIELD BETTER
CHANCES OF SHOWERS AND THUNDERSTORMS. CONFIDENCE IS LOW IN TIMING
AND PATTERN EVOLUTION THAT FAR OUT SO WILL JUST CARRY A 30 POP FOR
NOW. TEMPERATURES WILL BE ABOVE NORMAL OVER THE WEEKEND WITH A
COOLING TREND FOR EARLY NEXT WEEK AS A COLD FRONT PUSHES SOUTH
ACROSS THE AREA.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY
AS THE ATMOSPHERE CONTINUES TO MOISTEN. EARLY MORNING HZ/BR ALSO
POSSIBLE 09-13Z WITH INCREASING DEWPOINTS. EARLY THIS MORNING WE
ARE WATCHING A COMPLEX OF THUNDERSTORMS OVER NE WISCONSIN WHICH
WILL TAKE AIM AT NRN OHIO AFTER 12Z. EXPECTING THIS COMPLEX TO
UNDERGO SOME WEAKENING AS IT APPROACHES. REMNANTS OF THIS FEATURE
WILL RESULT IN ADDITIONAL STORM DEVELOPMENT EARLY THIS AFTERNOON
AND HAVE INCLUDED A VCTS IN ALL SITES. TIMING REMAINS IN QUESTION
BUT EXPECT PRETTY GOOD CHANCES FOR A THUNDERSTORM AT SOME POINT
THIS AFTERNOON...ESPECIALLY AT CLE/MFD/CAK/YNG WITH THE POTENTIAL
FOR SOME THUNDERSTORMS TO BE STRONG TO SEVERE.
MODELS ARE IN PRETTY GOOD AGREEMENT THAT WE ARE LOOKING FOR ANOTHER
ROUND OF THUNDERSTORMS TOWARDS THE END OF THE TAF CYCLE (04-12Z) AS
LOW PRESSURE TRACKS THROUGH THE SOUTHERN GREAT LAKES. THESE
THUNDERSTORMS COULD ONCE AGAIN BE STRONG WITH HEAVY RAINFALL
POSSIBLE.
OUTLOOK...MVFR PROBABLE WITH SHRA/TSRA BR TUESDAY AFTERNOON THROUGH
WEDNESDAY.
&&
.MARINE...
WINDS ON LAKE ERIE WILL MAINTAIN A WESTERLY COMPONENT AT 15 KNOTS OR
LESS TODAY. MULTIPLE ROUNDS OF THUNDERSTORMS ARE POSSIBLE ON THE
LAKE OVER THE NEXT 24 HOURS...ESPECIALLY TONIGHT AS A WAVE OF LOW
PRESSURE MOVES THROUGH THE SOUTHERN GREAT LAKES. THE AREA IS IN A
SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH TONIGHT. THIS SYSTEM
WILL PULL A COLD FRONT SOUTH ACROSS THE LAKE BEHIND IT ON WEDNESDAY
WITH WINDS SHIFTING TO THE NORTH AT 10-15 KNOTS INTO THURSDAY.
THE NORTHERLY FLOW WILL RESULT IN SOME INCREASE IN WAVE CONDITIONS
IN THE NEARSHORE WATERS AS WAVES BUILD TO 1 TO 3 FEET ON THURSDAY.
HIGH PRESSURE WILL LIGHT WINDS AND WAVES WILL RETURN ON FRIDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1242 PM CDT WED AUG 28 2013
.UPDATE...
18Z AVIATION DISCUSSION UPDATED BELOW.
UPDATED THE FORECAST THIS MORNING TO INCREASE PRECIPITATION
CHANCES FOR THE EASTERN AND SOUTHERN PORTIONS OF THE CWA. A LINE
OF SHOWERS AND THUNDERSTORMS CONTINUE TO PROGRESS EAST OF THE
REGION WITH THE LATEST HRRR INDICATING THE PCPN ENDING BETWEEN 1
AND 2 PM. HIGH TEMPERATURES TODAY COULD BE IMPACTED BASED ON HOW
LONG CLOUDS REMAIN ACROSS THE REGION. HAVE MADE SOME MINOR
ADJUSTMENTS FOR NOW AND WILL FINE TUNE AS NEEDED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH FRIDAY
A TROPICAL PLUME OF MOISTURE AND A SLIGHT WEAKENING OF THE UPPER
RIDGE...COMBINED WITH A WEAK...THOUGH NOT WELL RESOLVED...LOW
LEVEL JET...HELPING TO SUPPORT SOME VERY TALL STORMS THIS AM. AS
STORM PUSH EAST INTO SOMEWHAT WARMER MID LEVEL TEMPERATURES THEY
HAVE DISSIPATE RATHER RAPIDLY...HOWEVER REDEVELOPMENT ALONG THE
AXIS OF COOLEST MID LEVEL TEMPERATURES AND SOME DOWNWIND
PROPAGATION IS ENOUGH TO WARRANT POPS ACROSS MUCH OF THE CENTRAL
AND EASTERN CWA THROUGH THE REST OF THE DAY. H7 TEMPERATURES WILL
GENERALLY RANGE BETWEEN +12C AND +14C...SO EXPECTING ANY
REDEVELOPMENT WILL REMAIN ABOVE THE BOUNDARY LAYER. WITH A
EAST/SOUTHEAST LOW LEVEL FLOW...WILL SEE TEMPERATURES A LITTLE
WARMER THEN YESTERDAY...THOUGH NORTH OF HIGHWAY 212...CLOUD COVER
AND SHOWER ACTIVITY WILL HELP SUPPRESS HEATING SO WONT GO QUITE AS
WARM. THUS...WILL GO WITH HEAT ADVISORY FOR SOUTHERN COUNTIES.
THE PLUME OF TROPICAL MOISTURE PUSHES EAST TONIGHT...SO THURSDAY
WILL SEE WARMEST MID LEVEL TEMPERATURES ALONG WITH FULL SUN AND
SOUTHERLY FLOW. MODELS DO SHOW A LITTLE BETTER MIXING
POTENTIAL...SO WITH HIGHER TEMPERATURES COME SOMEWHAT LOWER
DEWPOINTS. FRIDAY WILL SEE SLIGHTLY LOWER MID LEVEL TEMPERATURES
AND GOOD MIXING CONDITIONS.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
THE UPPER LEVEL RIDGE WILL BEGIN TO DAMPEN FRIDAY NIGHT AS
SHORTWAVE ENERGY TRACKS ACROSS SOUTHERN CANADA AND NORTH DAKOTA.
THE RIDGE BEGINS TO REBUILD OVER THE ROCKIES ON SUNDAY...THEN
PUSHES OVER THE WESTERN HIGH PLAINS MONDAY AND TUESDAY.
A SURFACE BOUNDARY WILL TRACK ACROSS THE AREA EARLY IN THE
PERIOD...AND MAY BRING PRECIPITATION CHANCES FRIDAY NIGHT THROUGH
SATURDAY NIGHT. HIGH PRESSURE THEN DROPS OVER THE NORTHERN PLAINS
AND REMAINS DOMINANT THROUGH EARLY TUESDAY BEFORE GETTING PUSHED
EAST BY AN APPROACHING LOW PRESSURE TROUGH. WILL THEREFORE KEEP
THE PERIOD FROM SUNDAY THROUGH TUESDAY DRY.
THE WARM TEMPERATURES WILL CONTINUE INTO THE EARLY PART OF THE
WEEKEND...WITH HIGHS IN THE 90S SATURDAY. COOLER AIR THEN BEGINS
TO MOVE IN...WITH HIGHS BACK DOWN IN THE 80S SUNDAY AND MONDAY.
WITH THE UPPER RIDGE REBUILDING TUESDAY...WILL SEE TEMPS BACK UP
INTO THE UPPER 80S TO LOWER 90S.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED AT ALL TAF LOCATIONS THROUGH TONIGHT
AND THURSDAY MORNING. A SHORT WAVE TROUGH COMING UP THE BACKSIDE
OF THE UPPER RIDGE THIS AFTERNOON AND TONIGHT WILL BRING BACK SOME
SHOWERS AND STORMS TO THE REGION MAINLY WEST AND NORTH. THESE MAY
AFFECT MBG AND ABR.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR BUFFALO-
CLARK-CODINGTON-DEUEL-DEWEY-FAULK-HAMLIN-HAND-HUGHES-HYDE-
JONES-LYMAN-POTTER-SPINK-STANLEY-SULLY.
MN...NONE.
&&
$$
UPDATE...SD
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1112 AM CDT WED AUG 28 2013
.UPDATE...
UPDATED THE FORECAST THIS MORNING TO INCREASE PRECIPITATION
CHANCES FOR THE EASTERN AND SOUTHERN PORTIONS OF THE CWA. A LINE
OF SHOWERS AND THUNDERSTORMS CONTINUE TO PROGRESS EAST OF THE
REGION WITH THE LATEST HRRR INDICATING THE PCPN ENDING BETWEEN 1
AND 2 PM. HIGH TEMPERATURES TODAY COULD BE IMPACTED BASED ON HOW
LONG CLOUDS REMAIN ACROSS THE REGION. HAVE MADE SOME MINOR
ADJUSTMENTS FOR NOW AND WILL FINE TUNE AS NEEDED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH FRIDAY
A TROPICAL PLUME OF MOISTURE AND A SLIGHT WEAKENING OF THE UPPER
RIDGE...COMBINED WITH A WEAK...THOUGH NOT WELL RESOLVED...LOW
LEVEL JET...HELPING TO SUPPORT SOME VERY TALL STORMS THIS AM. AS
STORM PUSH EAST INTO SOMEWHAT WARMER MID LEVEL TEMPERATURES THEY
HAVE DISSIPATE RATHER RAPIDLY...HOWEVER REDEVELOPMENT ALONG THE
AXIS OF COOLEST MID LEVEL TEMPERATURES AND SOME DOWNWIND
PROPAGATION IS ENOUGH TO WARRANT POPS ACROSS MUCH OF THE CENTRAL
AND EASTERN CWA THROUGH THE REST OF THE DAY. H7 TEMPERATURES WILL
GENERALLY RANGE BETWEEN +12C AND +14C...SO EXPECTING ANY
REDEVELOPMENT WILL REMAIN ABOVE THE BOUNDARY LAYER. WITH A
EAST/SOUTHEAST LOW LEVEL FLOW...WILL SEE TEMPERATURES A LITTLE
WARMER THEN YESTERDAY...THOUGH NORTH OF HIGHWAY 212...CLOUD COVER
AND SHOWER ACTIVITY WILL HELP SUPPRESS HEATING SO WONT GO QUITE AS
WARM. THUS...WILL GO WITH HEAT ADVISORY FOR SOUTHERN COUNTIES.
THE PLUME OF TROPICAL MOISTURE PUSHES EAST TONIGHT...SO THURSDAY
WILL SEE WARMEST MID LEVEL TEMPERATURES ALONG WITH FULL SUN AND
SOUTHERLY FLOW. MODELS DO SHOW A LITTLE BETTER MIXING
POTENTIAL...SO WITH HIGHER TEMPERATURES COME SOMEWHAT LOWER
DEWPOINTS. FRIDAY WILL SEE SLIGHTLY LOWER MID LEVEL TEMPERATURES
AND GOOD MIXING CONDITIONS.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
THE UPPER LEVEL RIDGE WILL BEGIN TO DAMPEN FRIDAY NIGHT AS
SHORTWAVE ENERGY TRACKS ACROSS SOUTHERN CANADA AND NORTH DAKOTA.
THE RIDGE BEGINS TO REBUILD OVER THE ROCKIES ON SUNDAY...THEN
PUSHES OVER THE WESTERN HIGH PLAINS MONDAY AND TUESDAY.
A SURFACE BOUNDARY WILL TRACK ACROSS THE AREA EARLY IN THE
PERIOD...AND MAY BRING PRECIPITATION CHANCES FRIDAY NIGHT THROUGH
SATURDAY NIGHT. HIGH PRESSURE THEN DROPS OVER THE NORTHERN PLAINS
AND REMAINS DOMINANT THROUGH EARLY TUESDAY BEFORE GETTING PUSHED
EAST BY AN APPROACHING LOW PRESSURE TROUGH. WILL THEREFORE KEEP
THE PERIOD FROM SUNDAY THROUGH TUESDAY DRY.
THE WARM TEMPERATURES WILL CONTINUE INTO THE EARLY PART OF THE
WEEKEND...WITH HIGHS IN THE 90S SATURDAY. COOLER AIR THEN BEGINS
TO MOVE IN...WITH HIGHS BACK DOWN IN THE 80S SUNDAY AND MONDAY.
WITH THE UPPER RIDGE REBUILDING TUESDAY...WILL SEE TEMPS BACK UP
INTO THE UPPER 80S TO LOWER 90S.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
SHOWERS AND THUNDERSTORMS WILL TRACK ACROSS A GOOD PORTION OF THE
CWA DURING THE MORNING HOURS. BRIEF MVFR CONDITIONS ARE POSSIBLE
WITH THE STRONGER STORMS. OTHERWISE...VFR CONDITIONS WILL PREVAIL
ACROSS THE AREA TODAY AND TONIGHT.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR BUFFALO-
CLARK-CODINGTON-DEUEL-DEWEY-FAULK-HAMLIN-HAND-HUGHES-HYDE-
JONES-LYMAN-POTTER-SPINK-STANLEY-SULLY.
MN...NONE.
&&
$$
UPDATE...SD
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1229 AM CDT TUE AUG 27 2013
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH THURSDAY MORNING
CURRENT SURFACE ANALYSIS SHOWS A WEAK SURFACE LOW CENTERED OVER
THE KPIR AREA...WITH A WARM FRONT EXTENDING THROUGH KABR AND
K8D3 AND INTO WEST CENTRAL MINNESOTA. MODELS ARE SHOWING AN
ELONGATED AREA OF SHEARED OUT VORTICITY WORKING ITS WAY UP AND
OVER THE RIDGE. AREAS SOUTH OF THE WARM FRONT WILL LIKELY BE TOO
CAPPED FOR ANY CONVECTION TO DEVELOP /THE 700 MB TEMPERATURE OFF
THE MORNING KABR SOUNDING WAS 14 C/...HOWEVER CHANCES ARE DECENT
NORTH OF THE FRONT. THIS LOOKS LIKE IT WILL BE MAINLY OUR FAR
NORTHERN CWA TONIGHT. WITH OVER 2000 J/KG OF ML CAPE AND 40 TO 50
KTS OF 0-6 KM SHEAR PRESENT THIS EVENING...THERE IS CERTAINLY THE
CHANCE FOR ISOLATED SEVERE STORMS ALONG OUR NORTH. THE MOST RECENT
RUNS OF THE HRRR MODEL SEEM TO BE HANDLING THE SCENARIO
WELL...DEVELOPING STORMS ACROSS THE FAR NORTHWEST LATER THIS
AFTERNOON...AND THEN TRACKING ADDITIONAL ISOLATED SUPERCELLS ALONG
THE ND/SD BORDER BEFORE DROPPING THE CONVECTION INTO OUR FAR
NORTHEAST CWA LATER TONIGHT.
HOT TEMPERATURES CONTINUE TO AFFECT THE REGION THROUGH THE
REMAINDER OF THE SHORT TERM. MODEL 850 MB TEMPERATURES DO COOL
SLIGHTLY TUESDAY...WITH PERHAPS SOME DRIER AIR TRYING TO WORK INTO
THE REGION TUESDAY AND WEDNESDAY. HOWEVER...WITH MORE OF A NORTH
TO NORTHEAST SURFACE FLOW ON TUESDAY AND THEN WINDS SWITCHING BACK
TO THE SOUTHEAST ON WEDNESDAY...VERY SKEPTICAL ON DEWPOINTS DROPPING
MUCH LOWER THAN THE LOW TO MID 60S. HEAT INDICES DO APPEAR TO
REMAIN BELOW THE 100 DEGREE MARK HOWEVER. AS THE UPPER HIGH
WOBBLES AROUND THE CENTRAL PLAINS ADDITIONAL SHORTWAVE ENERGY IS
PROGGED TO MOVE ACROSS THE NORTHERN PLAINS. MODELS HAVE BEEN
FAIRLY CONSISTENT WITH THUNDERSTORM CHANCES ACROSS OUR WEST
TUESDAY NIGHT...AND THEN ACROSS OUR NORTH AND EAST ON WEDNESDAY
NIGHT AND THURSDAY MORNING. A 20 TO 30 KT LLJ IS ALSO PROGGED TO
SET UP ON WEDNESDAY NIGHT AND THURSDAY MORNING...ALTHOUGH AT THIS
POINT THE NOSE OF THE LLJ LOOKS TO BE PUSHING MORE INTO NORTH
DAKOTA...SO BETTER CHANCES STILL SEEM TO BE NORTH OF OUR CWA. WITH
ANY STORMS THAT CAN DEVELOP OVER THE NEXT COUPLE OF DAYS...ISOLATED
SEVERE STORMS ARE CERTAINLY POSSIBLE.
.LONG TERM...THURSDAY THROUGH MONDAY
THE UPPER RIDGE CONTINUES TO DOMINATE THE PATTERN AT THE START OF
THE EXTENDED. SAT/SUN THERE IS A SLIGHT FLATTENING OF THE RIDGE
SHOWN ON BOTH THE ECMWF AND THE GFS. HOWEVER BY MONDAY THE MODELS
DIVERGE WITH PLACEMENT OF THE RIDGE LEAVING FORECASTER CONFIDENCE
LOW OVER THE LABOR DAY WEEKEND.
MAIN CHALLENGE WILL BE DETERMINING TIMING AND PLACEMENT OF ANY WAVES
THAT RIDE OVER THE RIDGE. STUCK CLOSE TO ALLBLEND DUE TO
UNCERTAINTY AND CURRENTLY HAVE SOME POPS MENTIONED FOR THURSDAY
AND THEN AGAIN SAT/SUN. TEMPERATURES WILL BE VERY WARM WITH HIGHS
IN THE 90S AS LONG AS THE RIDGE HOLDS. WHEN IT FLATTENS OR MOVES
EAST...TEMPS SHOULD FALL ACCORDINGLY BACK CLOSER TO NORMAL.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
OTHER THAN POSSIBLE LATE NIGHT MVFR FOG AT KABR/KATY...VFR
CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH TUESDAY.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...SERR
LONG TERM...WISE
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
340 PM CDT TUE AUG 27 2013
.SHORT TERM...(Tonight and Wednesday)
Isolated shower activity will be ending this evening, as an easterly
wave moves northwest. HRRR model seems to have been the better
model, indicating rapid weakening showers this afternoon. The NAM
and GFS models had more extensive coverage this afternoon over the
Big Country and Concho Valley. In any case...all models show
precipitation ending by early evening with loss of the suns heating.
Some patchy stratus possible late tonight and early Wednesday
morning...due to moist vegetation and light winds. Temperatures
rebound into the lower and mid 90s Wednesday with dry conditions and
and mostly sunny skies.
.LONG TERM...(Thursday through Tuesday)
Dry and hot weather to prevail through the weekend.
The ECMWF and the GFS are still in good agreement, indicating that
once the wave moves out of the area tomorrow, the upper level high
pressure will settle back into the area. With the high dominating
the weather across the southern plains, looks like dry conditions
will prevail. The center of the high pressure will shift from the
mid Mississippi Valley on Wednesday, to Texas on Thursday, and into
the southern Rockies for the weekend. Since we dont see the center
of the high sit directly over West Central Texas, temperatures are
more likely to be in the mid and upper 90s to near 100 rather than
something much warmer. But in any case, dry and warmer than normal
conditions will be the rule.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 71 95 71 97 72 / 10 5 5 5 5
San Angelo 70 93 70 96 71 / 10 5 5 5 5
Junction 70 93 70 95 70 / 10 5 5 5 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
04/07
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
911 PM EDT WED AUG 28 2013
.SYNOPSIS...
A COLD FRONT WILL SLIDE SOUTH TO THE NORTH CAROLINA/VIRGINIA
BORDER BY THURSDAY MORNING. WEAK HIGH PRESSURE SHOULD BUILD INTO
THE AREA FROM THE NORTH THURSDAY INTO THURSDAY NIGHT BEFORE
SLIDING OFFSHORE ON FRIDAY INTO SATURDAY. THIS WILL BRING A
RETURN FLOW OF MOISTURE ALONG WITH AN ASSOCIATED WARM FRONT
LATER IN THE WEEKEND.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 840 PM EDT WEDNESDAY...
CLUSTERS OF SHRA/TSRA CONTINUE TO DEVELOP AND SPILL SE AHEAD OF
THE COLD FRONT NOW ALONG THE OHIO RIVER. THIS SUPPORTED BY
LINGERING INSTABILITY PER DECENT ML CAPES IN SPOTS OVER THE WEST
AND MORESO OUT EAST WHERE JUST RECOVERING FROM EARLIER
CLOUDS/SHRA. LATEST HRRR KEEPS COVERAGE GOING THROUGH AT LEAST
MIDNIGHT AND DROPS SHRA IN AN EAST-WEST ORIENTED BAND TOWARD
SOUTHERN VA/NW NC IN THE NEXT FEW HOURS WHERE SEEING SOME INCREASE
IN LOW LEVEL THETA-E ATTM. THIS MAY BE OVERDONE GIVEN LOW LEVEL
NW FLOW ALTHOUGH MOIST EVENING SOUNDINGS SHOW A GOOD VEERING JET
ALOFT SO WILL NEED TO KEEP SOME DECENT POPS IN ESPCLY NORTHERN
ZONES A FEW MORE HOURS DESPITE LOSS OF HEATING. WEAK WAVE ALONG
THE FRONT SHOULD FINALLY PUSH EAST OF THE REGION AFTER MIDNIGHT
ALLOWING THE FRONT TO OOZE SOUTH TO ALONG THE VA/NC BORDER BY
MORNING. THIS COULD AGAIN SPARK A FEW MORE SHRA OVERNIGHT SO
KEEPING IN THE EARLIER 20/30 POPS FOR MOST OF THE AREA THROUGH
DAYBREAK. THINK WIDESPREAD FOG SHOULD BE LIMITED SOMEWHAT BY
CLOUDS SO APPEARS MORE PATCHY COVERAGE IN SPOTS ESPCLY WHERE
EARLIER RAIN OCCURRED. TEMPS SLOW TO FALL THIS EVENING GIVEN MUGGY
CONDITIONS AND ONLY EXPECT A GRADUAL DECLINE INTO THE UPPER
60S/LOW 70S BY MORNING.
ON THURSDAY...THE WEAK BOUNDARY WILL BE LOCATED JUST TO OUR SOUTH.
THE COMBINATION OF LOW LEVEL MOISTURE AND SURFACE WIND CONVERGENCE
ALONG THE SOUTHERN BLUE RIDGE COULD PRODUCE SCATTERED SHOWERS AND
THUNDERSTORMS THURSDAY AFTERNOON. WENT WITH HIGH TEMPERATURES
THURSDAY FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE
SOUTHEAST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 245 PM EDT MONDAY
BY THURSDAY NIGHT OUR FORECAST AREA WILL BE WELL NORTH A SFC FRONT
WITH A WEAK LOW LEVEL EAST/NORTHEAST FLOW WHICH VEERS TO THE
EAST/SOUTHEAST ON FRIDAY. TIME CROSS SECTIONS SHOW MOISTURE
LINGERING BELOW 700 MB WITH SFC DEW POINTS REMAINING IN THE MID 60S.
THIS LOW LEVEL MOISTURE COMBINED WITH A WEAK UPSLOPE FLOW WILL
RESULT IN SCATTERED SHOWERS IN NW NC AND THE EAST FACING SLOPES OF
THE SOUTHERN BLUE RIDGE WHICH WILL BE CLOSEST TO THE 850MB THETA-E
AXIS.
RAIN CHANCES DIMINISH FRIDAY NIGHT AS WINDS BEGIN TO BACK IN
RESPONSE TO AN APPROACHING UPPER LEVEL SHORTWAVE FROM THE NORTHWEST.
BEST CHANCES FOR PRECIPITATION IN THE SHORT TERM PERIOD WILL BE
SATURDAY AS UPPER LEVEL SUPPORT ARRIVES AND DEEPER MOISTURE RETURNS.
HIGHEST CHANCES FOR SHOWERS AND STORMS SATURDAY WILL BE IN THE
MOUNTAINS...WHERE BETTER DYNAMICS ARE EXPECTED TO BE LOCATED.
FOR TEMPS...LEANED TOWARD THE COOLER GFS MOS...WHICH IS CLOSER TO
OUR LOCALLY DERIVED MOS GUIDANCE...DUE TO CLOUD COVER AND PRECIP
POTENTIAL.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 245 PM EDT WEDNESDAY
THE GFS/ECMWF/CANADIAN/GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT THAT
THE UPPER TROF...WHICH HAS BEEN PERSISTENT ACROSS THE EASTERN U.S.
FOR MOST OF THE SUMMER...AMPLIFIES BY EARLY NEXT WEEK.
THERE ARE SOME MINOR DIFFERENCE WITH REGARD TO AMPLIFICATION WITH
THE ECMWF FORECASTING A SLIGHTLY DEEPER/SLOWER EASTERN U.S. TROF
COMPARED TO THE GFS AND CANADIAN MODELS. WITH THE BLOCKY
PATTERN...LEANED TOWARD THE STRONGER ECWMF SOLUTION.
AS THE UPPER TROF DEEPENS...A STRONG COLD FRONT WILL PUSH THROUGH
MONDAY NIGHT/EARLY TUESDAY BRINGING COOLER TEMPS...DRIER
WEATHER...AND LOWER DEW POINTS FOR TUESDAY AND WEDNESDAY.
BEFORE THE FRONTAL PASSAGE...DIURNALLY DRIVEN SHOWERS AND STORMS
WILL BE FOUND SUNDAY AND MONDAY. LOCALLY HEAVY RAIN WILL BE POSSIBLE
AS PWATS WILL BE 1-2 STANDARD DEVIATIONS ABOVE NORMAL PER THE GEFS.
FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WENT BELOW GFS MOS
GUIDANCE FOR TEMPS WITH THE GEFS SHOWING 850MB TEMPS 1-2 STANDARD
DEVIATIONS BELOW NORMAL.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
AS OF 703 PM EDT WEDNESDAY...
BANDS OF DEEPER CONVECTION CONTINUE TO SPILL SE UNDER NW FLOW
ALOFT AND SUPPORTED BY A WESTERLY LOW LEVEL JET AHEAD OF A COLD
FRONT TO THE NW. THIS IN ADDITION TO WEAK SHORTWAVE ENERGY MAY
KEEP SHRA/TSRA ONGOING WHILE SPILLING FARTHER SOUTH ACROSS THE
REGION THIS EVENING. THUS INCLUDING SOME MVFR CIGS/VSBY MENTION AT
MOST SITES BEFORE MIDNIGHT WITH LOCATIONS SUCH AS KLWB/KBLF
POSSIBLY SEEING A PERIOD OF IFR WITH A STRONGER TSRA. EXPECTING
LIGHTER SHOWERS FARTHER EAST ALTHOUGH SPOTS ALONG THE KBCB-KROA-
KLYH COULD SEE A PASSING TSRA BEFORE COVERAGE FADES OR SHIFTS
FARTHER TO THE SE.
MODELS TRACK THE PRECIPITATION EAST AND OFFSHORE OVERNIGHT BUT
SHOW LOTS OF LEFTOVER LOW LEVEL MOISTURE IN THE NORTH AND WEST
LATE. THIS COULD ALLOW CLOUDS TO LINGER WITH CIGS LOWERING BACK
TO MVFR/IFR ALONG WITH AREAS OF FOG ESPECAILLY AT KLWB/KBLF/KBCB
AND ANY LOCATION THAT SEES HEAVIER RAINFALL FROM THIS EVENING.
FLOW TURNS NE EARLY THURSDAY WITH POTENTIAL FOR LOWER CIGS TO
REMAIN IN PLACE INTO THE AFTERNOON ALTHOUGH CONFIDENCE LOW ON JUST
HOW LONG MVFR/IFR CONDITIONS MAY LINGER. IN ADDITION...SPOTTY
SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE AS WEAK
DISTURBANCES RIDE ACROSS THE AREA FROM THE GREAT LAKES OVERTOP
THE WEAK FLOW IN PLACE NEAR THE SURFACE AS HIGH PRESSURE BUILDS
IN. FOR NOW WILL KEEP POOR FLYING CONDITIONS IN THROUGH MID OR
LATE MORNING THURSDAY FOR MOST LOCATIONS...AND THEN SHOW SLOW
IMPROVEMENT TOWARD VFR WHICH MAY NOT OCCUR UNTIL AFTERNOON IN
SPOTS ALONG THE BLUE RIDGE.
EXPECT A RETURN TO OVERALL VFR CONDITIONS FOR FRIDAY UNDER HIGH
PRESSURE...WITH ONLY ISOLATED SHOWERS AT BEST FRIDAY AFTERNOON AND
SATURDAY. DEEPER MOISTURE WILL MAKE A RETURN LATER IN THE WEEKEND
WITH MORE IN THE WAY OF CONVECTIVE DRIVEN SUB-VFR CONDITIONS
POSSIBLE WITH A PASSING WARM FRONT SUNDAY...AND ANOTHER COLD FRONT
LATER MONDAY. OTHERWISE SOME PATCHY FOG LIKELY DURING THE
OVERNIGHTS INTO SATURDAY...WITH LATE NIGHT/EARLY MORNING MVFR/IFR
CONDITIONS POSSIBLE ESPECAILLY AT THE VALLEY LOCATIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/KK/WP
NEAR TERM...JH/KK/WP
SHORT TERM...PH
LONG TERM...PH
AVIATION...JH/KK/WP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
621 PM CDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE MAIN FOCUS TONIGHT INTO TOMORROW IS WITH THE CHANCES OF
PRECIPITATION AND WHETHER ANY FOG WILL DEVELOP OVERNIGHT AGAIN.
THE UPPER LEVEL FLOW CONTINUES TO BE SHAPED BY BROAD RIDGING THAT
IS CENTERED OVER THE PLAINS AND EXTENDS FROM THE SOUTHEASTERN US
TO THE SOUTHWESTERN US. ANY PRECIPITATION HAS COME ALONG THE NORTHERN
PERIPHERY OF THIS RIDGE AS MID LEVEL SHORT WAVE TROUGHS TRACK
ALONG THE RIM. THERE CURRENTLY ARE A PAIR OF SHORT WAVE TROUGHS
THAT WILL NEED MONITORING INTO TOMORROW...ONE WEAK ONE IN THE
DAKOTAS/WESTERN MINNESOTA AND ANOTHER RUNNING INTO MONTANA. AT THE
SURFACE...A COLD FRONT HAS STALLED OUT ACROSS CENTRAL IOWA WITH
RIDGING ACROSS THE NORTHERN GREAT LAKES. DEW POINTS HAVE REALLY
POOLED ALONG THE NORTHERN SIDE OF THIS FRONT WITH MID/UPPER 70S
ANALYZED FROM CENTRAL ILLINOIS THROUGH EASTERN/NORTHERN IOWA.
EARLIER STRATUS HAS ALSO BECOME MORE MIXED AS THE DAY HAS GONE ON
TODAY...WHICH HAS LEAD TO SOME QUICK WARM UPS AS WELL.
GOING INTO TONIGHT...THE FIRST SHORTWAVE IN THE DAKOTAS/MINNESOTA
WILL PROPAGATE TO THE EAST AND WILL HELP TO LIFT THE FRONT BACK TO
THE NORTH AS A WARM FRONT ACROSS SOUTHERN MINNESOTA. THE 18.12Z
NAM/GFS AND 18.18Z RAP SHOWS THE POOL OF HIGHEST 0-3KM MUCAPE
LIFTING NORTH AS WELL IN MINNESOTA AND BECOMING ORIENTED MORE
NORTH TO SOUTH FROM CENTRAL MINNESOTA TO EASTERN IOWA OVERNIGHT.
THE BEST LOW LEVEL MOISTURE TRANSPORT APPEARS TO BE IN CENTRAL
MINNESOTA AS WELL WHERE THE STRONGER PUSH/CONVERGENCE IS FROM THE
SOUTH. HAVE KEPT SOME LOW CHANCES OF SHOWERS/STORMS OVERNIGHT IN
PORTIONS OF SOUTHEAST MINNESOTA/NORTHEAST IOWA TO ACCOUNT FOR
THIS...BUT CONFIDENCE IS NOT OVERLY HIGH THAT THE FORCING WILL BE
ENOUGH TO PRODUCE SOME CONVECTION.
THE HIGHER CHANCES FOR PRECIPITATION WILL COME ON THURSDAY AS THE
SECOND MID LEVEL SHORT WAVE TROUGH PROPAGATES EAST FROM MONTANA
THROUGH THE DAKOTAS ON TOWARD THE UPPER GREAT LAKES. IT APPEARS
THAT AN MCS WILL DEVELOP OVER THE DAKOTAS FROM THIS FEATURE AND
TRACK TO THE EAST INTO MINNESOTA TOMORROW MORNING. AS THE
SHORTWAVE ENTERS MINNESOTA/NORTHERN WISCONSIN LATE TOMORROW
MORNING/AFTERNOON...CONVECTION MAY DEVELOP ALONG THE WARM FRONT
WHICH WILL BE LIFTING TO THE NORTH AS A LOW MOVES INTO CENTRAL
MINNESOTA. WITH THE HIGH INSTABILITY ON THE ORDER OF 2000-4000
J/KG AND DECENT SHEAR...CAN NOT RULE OUT SOME SEVERE WEATHER
ACROSS NORTHERN WISCONSIN THE AFTERNOON HOURS WITH LARGE
HAIL/DAMAGING WINDS THE MAIN THREATS. NORTHERN WISCONSIN IS ALSO
THE LOCATION OF THE HIGHEST PRECIPITATION CHANCES AS THIS TROUGH
MOVES THROUGH GOING INTO THURSDAY NIGHT.
WITH LIGHT WINDS AND HIGH AMOUNTS OF LOW LEVEL MOISTURE STILL IN
THE REGION...CAN NOT RULE OUT SOME FOG TONIGHT...PARTICULARLY IN
WESTERN WISCONSIN WHICH WILL BE CLOSER TO THE HIGH AND FURTHER
FROM ANY CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE COMPLEX WILL MOVE THROUGH ON THURSDAY NIGHT WITH A COLD FRONT
DROPPING DOWN ACROSS THE REGION ON FRIDAY. THE 28.12Z NAM/GFS
FORECAST SOUNDINGS DIFFER ON THE AMOUNT OF CAPPING THAT WILL BE IN
PLACE AHEAD OF THIS FRONT WITH THE NAM SHOWING MORE OF IT AND THE
GFS LESS. THUS...THE NAM IS MAINLY DRY WITH THE FROPA WHILE THE
GFS PRODUCES SOME QPF. KEPT SOME PRECIPITATION CHANCES IN THERE
FOR NOW...MAINLY IN WESTERN WISCONSIN.
TEMPERATURES WARM UP AHEAD OF THIS FRONT WITH HIGHS GOING BACK
INTO THE 90S ACROSS MUCH OF NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN. WITH HEAT INDICES AROUND 100F IN THE AFTERNOON...MAY
HAVE TO DO A HEAT ADVISORY FOR THIS REGION.
BEYOND THIS...A BIG PATTERN CHANGE IS ON THE WAY FOR SUNDAY AS A
MID LEVEL TROUGH DIGS DOWN FROM CANADA AND BRINGS A MUCH COOLER
AIR MASS DOWN INTO THE REGION. 850MB TEMPERATURES...WHICH
GENERALLY HAVE BEEN IN THE +15C TO +25C RANGE THE PAST WEEK...WILL
DROP TO ABOUT +7C SUNDAY NIGHT AFTER THE COLD FRONT SWINGS
THROUGH. WHILE STORMS LOOK POSSIBLE WITH THE COLD FRONT COMING
THROUGH...THE TIME OF THE DAY DOES NOT LOOK FAVORABLE FOR SEEING
SEVERE WEATHER AS THE FRONT WILL LIKELY COME THROUGH IN THE
MORNING BEFORE ANY HIGH INSTABILITY CAN BUILD. HIGH PRESSURE THEN
SETTLES IN FOR THE EARLY PART OF NEXT WEEK WITH MUCH COOLER AND
SEASONABLE TEMPERATURES ON TAP.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 620 PM CDT WED AUG 28 2013
UPPER LEVEL RIDGING REMAINS ENTRENCHED OVER THE REGION THIS
EVENING LEADING TO A VERY WEAK SURFACE PATTERN. THIS MAKES IT VERY
TOUGH TO DETERMINE WHERE THE REMAINS OF THE WEAK FRONT ARE. BEST
GUESS IS THAT WHAT REMAINS OF IT IS FORMING A WARM FRONT ACROSS
SOUTHERN SOUTH DAKOTA AND MINNESOTA. THIS BOUNDARY IS EXPECTED TO
CONTINUE LIFTING NORTH OVERNIGHT AS A SURFACE LOW FORMS OVER NORTH
DAKOTA IN RESPONSE TO A SHORT WAVE TROUGH COMING ACROSS MONTANA
WITH A COMPLEX OF STORMS FORMING WELL NORTH OF THE AREA. BUFKIT
SOUNDINGS FROM THE 28.18Z NAM AND 28.21Z RAP SUGGEST THE MID LEVEL
CAP WILL REMAIN IN PLACE TONIGHT AS THE FRONT LIFTS BACKS THROUGH
SO HAVE OPTED TO KEEP THE FORECAST DRY. THESE SOUNDINGS ALSO SHOW
THE BAND OF MID LEVEL MOISTURE CURRENTLY OVER MINNESOTA INTO
WESTERN WISCONSIN WILL REMAIN IN PLACE WITH SCATTERED TO BROKEN
CLOUDS ASSOCIATED WITH IT. FEEL THIS BAND OF CLOUDS WILL LIMIT THE
FOG POTENTIAL FOR TONIGHT WITH ONLY A SHORT PERIOD OF MVFR
CONDITIONS POSSIBLE LATE TONIGHT INTO EARLY THURSDAY MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
326 PM CDT TUE AUG 27 2013
.SHORT TERM...
TONIGHT AND WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM.
HEAT ADVISORY REMAINS IN EFFECT UNTIL 01Z WEDNESDAY. SEVERAL
AUTOMATED SITES HAVE ALREADY REACHED THE 100 DEGREE HEAT INDEX
VALUE...AND MORE SHOULD REACH OVER THE NEXT FEW HOURS. GOOD MIXING
WITH SOUTHWEST WINDS HAVE HELPED TEMPERATURES RISE INTO THE LOWER TO
MID 90S. MADISON MAY GET CLOSE TO RECORD HIGH OF 95.
COLD FRONT IS EXPECTED TO SHIFT SOUTHWARD THROUGH THE AREA MAINLY
THIS EVENING. HRRR AND WRF 4KM MODELS NOW BRING THE FRONT THROUGH
THE AREA BETWEEN 00Z AND 06Z WEDNESDAY. THE HRRR IS SHOWING LITTLE
IN THE WAY OF ANY SHOWER/STORM ACTIVITY...WITH THE WRF 4KM MODEL
SHOWING A BROKEN LINE OF WEAK TO MODERATE SHOWERS/A FEW STORMS WITH
THE FRONT. UPWARD VERTICAL MOTION WITH THE FRONT IS EXPECTED TO BE
SOMEWHAT WEAK...WITH THE NAM TOO AGGRESSIVE WITH LOW LEVEL
FRONTOGENESIS RESPONSE.
500MB VORTICITY MAXIMUM OVER NORTHERN WISCONSIN IS EXPECTED TO SLIDE
SOUTHEAST AND CLIP THE NORTHEAST PORTIONS OF THE FORECAST AREA LATE
THIS AFTERNOON AND EARLY THIS EVENING. ADJUSTED AREA FORECAST
SOUNDINGS SHOWING CAP NEARLY MIXING OUT BY 22Z TUESDAY...WITH AT
LEAST 2000 J/KG MEAN LAYER CAPE AND DEEP LAYER SHEAR OF 30 TO 40
PLUS KNOTS...BEST SHEAR TOWARD SHEBOYGAN. SOME INDICATION FOR
ROTATING STORMS PER SPC SSEO PAGE AS WELL. IF CONVECTION DOES
DEVELOP...SEVERE STORMS ARE POSSIBLE GIVEN THESE PARAMETERS...WITH
STRONG WINDS AND LARGE HAIL THE MAIN HAZARDS. SEE LATEST SPC DAY 1
OUTLOOK AND RECENT MESOSCALE DISCUSSION FOR MORE INFORMATION.
GIVEN SOME UNCERTAINTY WITH HOW MUCH CONVECTION WILL
FORM...CONTINUED CHANCE POPS IN THE NORTHERN AND EASTERN PORTIONS OF
THE AREA...CLOSEST TO THE PASSING 500MB VORTICITY MAXIMUM AND BETTER
SHEAR.
WARM TEMPERATURES REMAIN ACROSS THE AREA AFTER FRONTAL PASSAGE LATER
TONIGHT INTO WEDNESDAY...AS WELL AS DEW POINTS IN THE UPPER 60S TO
LOWER 70S. SOME CONCERN WITH CLOUDS OVER NORTHERN WISCONSIN WILL
PUSH SOUTHWARD LATER TONIGHT AND LINGER INTO WEDNESDAY. BROUGHT IN
THESE CLOUDS LATER TONIGHT...BUT MIXED THEM OUT WEDNESDAY. WINDS
WILL SHIFT TO THE NORTH NORTHEAST DURING LATER TONIGHT INTO
WEDNESDAY. ANY FOG THAT DEVELOPS SHOULD REMAIN PATCHY...THOUGH GIVEN
HIGH DEW POINTS MAY BECOME MORE WIDESPREAD. LATER SHIFTS WILL HAVE
TO MONITOR.
QUIET WEATHER IS EXPECTED WEDNESDAY...WITH SOME DIURNAL CUMULUS
POSSIBLE IN THE AFTERNOON. HIGHS WILL STILL REACH WELL INTO THE 80S
AWAY FROM THE LAKE...WITH AROUND 80 NEAR IT.
WEDNESDAY NIGHT THROUGH SATURDAY...FORECAST CONFIDENCE MEDIUM
THE BROAD UPPER RIDGE WILL BE CENTERED OVER THE SOUTH CENTRAL USA THROUGH
THE PERIOD WITH NW FLOW ALOFT OVER WI. AT THE SFC...HIGH PRESSURE
WILL PREVAIL OVER SRN WI WED NT AND THU...BUT HIGH CLOUDS WILL
INCREASE ON THU AS A SLOW MOVING WAVE OF LOW PRESSURE APPROACHES
FROM THE NW. THE HIGH CLOUDS MAY KEEP TEMPS DOWN JUST A LITTLE FOR
THU...BUT STILL A WARM AND HUMID DAY.
A SLOW MOVING WAVE OF LOW PRESSURE WILL THEN TRACK ACROSS THE
REGION FROM THU NT INTO FRI...BUT ON SOME MODELS COULD LINGER INTO
SAT. A COUPLE WEAK VORTICITY MAXIMUMS WILL HELP GUIDE THE LOW SEWD
DURING THIS PERIOD. BEST TIME PERIOD FOR PCPN CHANCES IS THU NT
AND FRI WHEN LOW TO MID LEVEL WARM ADVECTION AND FRONTOGENESIS
AFFECTS THE REGION. SHOWALTER INDICES INCREASE TO -4C FOR LATE THU
NT WHILE LIS FOR FRI COULD REACH -8C. EXPECT THIS LIFT AND
INSTABILITY TO OVERCOME WEAK CAPPING SO POPS MAX OUT AROUND 50-60
PERCENT EITHER THU NT OR FRI. LOW POPS THEN LINGER INTO SATURDAY
SINCE LOW COLD BE SLOW TO DEPART. MAX HEAT INDICES DURING THIS
TIME WILL RANGE FROM THE MID 80S TO MID 90S WITH GREATEST HEAT
OVER SOUTH CENTRAL WI. SOME COOLING IS EXPECTED EACH DAY IN FAR
ERN WI VIA THE LAKE MI LAKE BREEZE.
.LONG TERM...
SUNDAY THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM
EXTENDED MODELS CONTINUE TO PRODUCE STRONG CYCLOGENESIS OVER SRN
CANADA FOR THE WEEKEND. THE LOW WILL MOVE EAST ACROSS SRN CANADA
WITH THE TRAILING COLD FRONT EXPECTED TO ARRIVE OVER SRN WI EITHER
SUN OR SUN NT. MODELS ARE STILL HAVING A DIFFICULT TIME ON THE
STRENGTH OF COOLING WITH THE FROPA BUT OVERALL MUCH COOLER TEMPS
ARE EXPECTED FOR EARLY NEXT WEEK COMPARED TO A COUPLE DAYS AGO.
HIGH TEMPS IN THE 70S ARE FORECAST FOR LABOR DAY AND TUE. POPS
CHANCES REMAIN LOW WITH THE MOSTLY DRY FROPA AND THEN DRY AFTER
FROPA.
&&
.AVIATION/00Z TAFS/...
PREVAILING VFR CONDITIONS EXPECTED THROUGH
THIS EVENING...WITH MVFR/IFR VISIBILITIES POSSIBLE IN ANY STORMS
WITH PASSING COLD FRONT. FOG WITH MVFR/IFR VISIBILITIES POSSIBLE
BETWEEN 06Z AND 14Z WEDNESDAY. VFR CONDITIONS RETURN FOR THE REST OF
WEDNESDAY...AS HIGH PRESSURE MOVES INTO THE REGION.
SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE BETWEEN 00Z AND 06Z
WEDNESDAY AT TAF SITES...BEST CHANCES AT THE EASTERN SITES. SOME
UNCERTAINTY IF STORMS WILL FORM AND HOW WIDESPREAD THEY WILL BE...SO
WILL LEAVE VICINITY WORDING IN TAFS FOR NOW. MVFR/IFR VISIBILITIES
POSSIBLE WITH ANY STORMS...ALONG WITH GUSTY WINDS AND HAIL.
GUSTY SOUTHWEST WINDS ARE EXPECTED INTO EARLY THIS EVENING...BEFORE
COLD FRONT PUSHES SOUTH THROUGH THE AREA BETWEEN 00Z AND 06Z
WEDNESDAY. LIGHT WINDS SHIFT TO THE NORTH NORTHEAST BEHIND THE
FRONT...THEN REMAIN NORTH NORTHEAST THROUGH WEDNESDAY. MODERATE
NORTH NORTHEAST WINDS ARE EXPECTED AT THE EASTERN TAF SITES BY
WEDNESDAY AFTERNOON.
&&
.MARINE...PATCHY FOG SEEMS TO HAVE MIXED OUT ON WEB CAMERAS AT
SHEBOYGAN AND PORT WASHINGTON...WITH MODERATE SOUTH WINDS MIXING
THIS FOG OUT. GUSTY WINDS AT MARINE OBSERVATION SITES ARE AT SMALL
CRAFT CRITERIA...BUT THESE SHOULD BEGIN TO WEAKEN SHORTLY...SO WILL
NOT ISSUE AN ADVISORY.
SHOULD SEE AT LEAST PATCHY FOG DEVELOP LATER TONIGHT INTO EARLY
WEDNESDAY WITH MOIST AIRMASS OVER THE COOL LAKE WATERS. SOME
POTENTIAL FOR MORE WIDESPREAD FOG DURING THIS TIME.
KEPT CHANCE WORDING FOR SHOWERS AND THUNDERSTORMS THROUGH THIS
EVENING. SOME UNCERTAINTY WITH IF AND HOW WIDESPREAD STORMS WILL
BE...GIVEN WEAK COLD FRONT MOVING THROUGH. SEVERE STORMS WITH STRONG
WINDS AND LARGE HAIL ARE POSSIBLE IF ANY STORMS DO DEVELOP. QUICK
WIND SHIFT TO THE NORTH NORTHEAST IS EXPECTED WITH THE FRONTAL
PASSAGE LATER THIS EVENING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR WIZ046-047-051-052-
056>060-062>072.
LM...NONE.
&&
$$
TONIGHT/WEDNESDAY AND AVIATION/MARINE...WOOD
WEDNESDAY NIGHT THROUGH TUESDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1239 PM CDT TUE AUG 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM CDT TUE AUG 27 2013
..CURRENTLY AS OF 08Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED AN UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUE TO ROTATE AROUND THE RIDGE...TRACKING FROM ARIZONA INTO THE
DAKOTAS AND THE FORECAST AREA. PRECIPITABLE WATER VALUES MAX OUT IN
THE 2-2.25 INCH RANGE FROM CENTRAL MN INTO NORTHERN WI PER RAP
ANALYSIS. CLUSTERS OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
MONSOONAL SHORTWAVES AS WELL AS 850MB-700MB MOISTURE TRANSPORT HAVE
BEEN TRACKING THROUGH THIS PRECIPITABLE WATER MAX. BLOWOFF FROM THIS
CONVECTION ENCOMPASSES MUCH OF THE FORECAST AREA. AIRMASS IS VERY
WARM ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. THE 00Z MPX RAOB
REPORTED A 25C 850MB TEMP AND 27C 925MB TEMP...WHICH TRANSLATED TO A
HIGH YESTERDAY OF 97F AT MSP. BETWEEN THE HOT TEMPERATURES
YESTERDAY...THE BLOWOFF...A LIGHT SOUTHERLY BREEZE AND DEWPOINTS
HOLDING IN THE LOW 70S...TEMPERATURES HAVE STRUGGLED TO DROP THIS
MORNING. READINGS ARE STILL MAINLY BETWEEN 75 AND 80. SURFACE
PRESSURE ANALYSIS SHOWED LOW PRESSURE NEAR MONTEVIDEO MN...WITH A
WARM FRONT STRETCHING INTO TAYLOR COUNTY AND A COLD FRONT BACK INTO
CHAMBERLAIN SOUTH DAKOTA.
..HAZARDS..
1. HEAT. HAVE KEPT ALL GOING HAZARDS INTACT. CONSIDERED UPGRADING
FLOYD...CHICKASAW AND FAYETTE COUNTIES TO EXCESSIVE HEAT
WARNING...BUT HEAT INDICES APPEAR MARGINAL TO DO SO.
2. STORMS. SEVERE POTENTIAL...PARTICULARLY THIS AFTERNOON NORTH AND
EAST OF I-94.
3. FOG LATE TONIGHT...WHICH COULD END UP BEING DENSE...ESPECIALLY
WHERE IT RAINS.
..SYNOPTIC OVERVIEW..
THE SUBTROPICAL RIDGE OVER KANSAS AND MISSOURI IS PROGGED TO STAY
PUT THROUGH TONIGHT. HOWEVER...A CHANGE IN THE UPPER AIR PATTERN IS
TO HAVE SOME RIDGE BUILD NORTH TONIGHT INTO THE DAKOTAS. THIS...IN
TURN...HELPS TO TURN THE FLOW MORE NORTHWESTERLY OVER THE FORECAST
AREA. A SERIES OF MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE ARE
FORECAST TO COME THROUGH NORTHEASTERN PORTIONS OF THE FORECAST AREA
THROUGH TONIGHT...HELPING TO PUSH THE SURFACE LOW AND COLD FRONT
SOUTHEAST THROUGH THE ENTIRE AREA BY 12Z WEDNESDAY.
..DETAILS..
PRECIPITATION...WITH 850MB AND 700MB MOISTURE TRANSPORT FOCUSED INTO
THE AREA NORTHEAST OF I-94 THIS MORNING...THERE REMAINS POTENTIAL
FOR CONVECTION JUST FROM THIS THERMODYNAMIC FORCING. HOWEVER...THINK
THE GREATER POTENTIAL FOR CONVECTION WILL COME THIS AFTERNOON AS A
SHORTWAVE PRESENTLY WEST OF FARGO COMES THROUGH CENTRAL WISCONSIN AT
PEAK HEATING. VERY GOOD MODEL CONSENSUS FOR CONVECTION TO OCCUR
NORTHEAST OF I-94 IN THE AFTERNOON...WITH EVEN A POSSIBILITY OF IT
EXTENDING BACK TOWARDS LA CROSSE. THIS CONVECTION WILL SLIDE
SOUTHEAST OF THE AREA DURING THE EVENING...WITH ALL OF IT LIKELY OUT
BY 03Z. DRY CONDITIONS ARE EXPECTED ELSEWHERE DUE TO CAPPING AND
LIMITED CONVERGENCE ON THE COLD FRONT...AND DRY CONDITIONS ARE
ANTICIPATED ONCE THE FRONT PASSES AS SUBSIDENCE AND DRYING WORK IN.
SEVERE POTENTIAL...0-6KM SHEAR IS DECENT IN THE MORNING...35-45 KT
NORTHEAST OF I-94. HOWEVER...NOT ANTICIPATING MUCH OF THE MORNING
CONVECTION TO BE ABLE TO UTILIZE THIS SHEAR. DURING THE AFTERNOON
WHEN CAPE IS AT ITS HIGHEST...THE 0-6KM SHEAR IS WEAKENING TO 30-35
KT. NONETHELESS...WITH MLCAPES OF 2000-2500 FT COMBINING WITH THIS
SHEAR SHOULD ALLOW FOR SOME STORM ORGANIZATION...LIKELY IN THE FORM
OF MULTICELLS WITH A SUPERCELL POSSIBLE. FREEZING LEVELS UP NEAR
16000 FT SHOULD LIMIT HAIL...BUT CERTAINLY DAMAGING WINDS AND VERY
HEAVY RAIN ARE POSSIBLE GIVEN THE UNSEASONABLY WARM...MOIST
ENVIRONMENT.
HEAT...925MB TEMPERATURES TODAY ARE PROGGED VERY SIMILAR TO
YESTERDAY AHEAD OF THE COLD FRONTAL PASSAGE...RUNNING BETWEEN
27-29C. SO WE SHOULD SEE READINGS THAT ARE SIMILAR AS WELL. AROUND
CHARLES CITY THE READINGS APPROACH 30C...SO IT IS POSSIBLE THEY WILL
END UP A LITTLE WARMER.
LASTLY...A POTENTIAL ISSUE TO DEAL WITH LATE IN THE NIGHT IS FOG.
THE FRONT THAT COMES THROUGH TONIGHT IS QUITE SHALLOW AND STRUGGLES
TO GET THESE HIGHER DEWPOINTS OUT OF HERE. WITH COOLER AIR COMING IN
BEHIND THE FRONT AND LIGHT SURFACE WINDS...WE MAY END UP WITH SOME
SHALLOW FOG...PARTICULARLY SOUTHWEST OF I-94. SREF VISIBILITY PROGS
SHOW THIS NICELY. HAVE RAISED THE FOG COVERAGE AND WILL HAVE TO
WATCH FOR POSSIBLE DENSE FOG.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 316 AM CDT TUE AUG 27 2013
..HAZARDS..
1. HEAT. DEWPOINTS LOOK A LITTLE BIT HIGHER FOR WEDNESDAY...THOUGH
TEMPERATURES WILL NOT BE NEARLY AS WARM THE PAST FEW DAYS.
THEREFORE...HEAT INDICES ONLY TOP OUT IN THE 90S...JUST BELOW
ADVISORY CRITERIA. FARTHER AHEAD...AN ADVISORY IS LOOKING MORE
LIKELY FOR FRIDAY...PARTICULARLY NORTHEAST IOWA AND FAR SOUTHWEST
WI. NO ADVISORIES NEEDED NOW FOR THE WEEKEND.
..SYNOPTIC OVERVIEW..
27.00Z MODEL GUIDANCE IN GOOD AGREEMENT SHOWING THAT THE SUBTROPICAL
RIDGE OVER KANSAS AND MISSOURI WILL RETROGRADE WESTWARD INTO THE
FOUR CORNERS REGION BY SATURDAY. THE LAST COUPLE OF DAYS MODELS HAD
SUGGESTED THAT THE RIDGE WOULD HEAD BACK EAST. HOWEVER...THIS IS NOW
DELAYED BECAUSE OF A SHORTWAVE TROUGH COMING OUT OF SOUTHWEST CANADA
ON FRIDAY THAT ENDS UP DIGGING INTO THE GREAT LAKES REGION ON
SUNDAY. THE 26.00Z ECMWF WAS FIRST TO SHOW THIS AND NOW ALL MODELS
HAVE CAPTURED ONTO THE IDEA. THE ONLY QUESTION NOW IS TIMING AND
AMPLIFICATION OF THIS TROUGH...WHICH THERE IS A DECENT SPREAD ON
COME SUNDAY.
..DETAILS..
WITH THE FRONTAL BOUNDARY SOUTH OF THE AREA ON WEDNESDAY AND HIGH
PRESSURE IN PLACE...HAVE CONTINUED THE DRY FORECAST. AS MENTIONED IN
THE HAZARDS SECTION...HIGHER DEWPOINTS DOES RAISE CONCERN FOR
EXTENSION IN THE HEAT ADVISORY. HOWEVER...925MB TEMPS OF 25-27C WILL
RESULT IN COOLER HIGHS...KEEPING HEAT INDICES BELOW ADVISORY LEVEL.
A SERIES OF SHORTWAVES ARE PROGGED TO COME ACROSS THE NORTHERN
PLAINS AND INTO THE NORTHERN GREAT LAKES REGION WEDNESDAY NIGHT
THROUGH FRIDAY. THE SHORTWAVES WEDNESDAY NIGHT AND THURSDAY ARE
PROGGED TO HELP BRING THE COLD FRONT BACK TOWARDS US...AND
ISENTROPIC LIFT/MOISTURE TRANSPORT OVER THE FRONT RESULTS IN CONCERN
FOR CONVECTION. THE GREATEST CHANCES FOR CONVECTION WEDNESDAY NIGHT
AND THURSDAY WILL TRACK JUST NORTH OF THE AREA...CLOSER TO THE
SHORTWAVES...BUT THE ISENTROPIC LIFT COULD SPREAD SOME SHOWERS AND
THUNDERSTORMS DOWN INTO THE FORECAST AREA...ESPECIALLY WEST OF THE
MS RIVER AND OVER NORTH CENTRAL WISCONSIN. HAVE CONTINUED 20-30
PERCENT CHANCES. THESE CHANCES GRADUALLY ENCOMPASS MORE OF THE AREA
HEADING INTO THURSDAY NIGHT AND ESPECIALLY FRIDAY. ON FRIDAY...
MODELS ARE IN GOOD AGREEMENT SHOWING A SHORTWAVE COMING THROUGH
CENTRAL MN AND SOUTHEAST INTO THE FORECAST AREA AT THE TIME OF PEAK
HEATING. 0-6KM SHEAR ONLY PROGGED 20-25 KT...SO NOT THINKING SEVERE
AT THIS TIME. TEMPERATURES WILL COOL DOWN BRIEFLY ON THURSDAY
BETWEEN CLOUDS/POTENTIAL CONVECTION AND 925MB TEMPS OF 22-26C.
HOWEVER...TEMPERATURES LOOK TO SHOOT BACK UP ON FRIDAY AHEAD OF THAT
SHORTWAVE COMING THROUGH. COOLING WILL OCCUR FRIDAY NIGHT WITH
PASSAGE OF THE SHORTWAVE TROUGH.
HEADING INTO LABOR DAY WEEKEND...WARM AIR COULD TRY TO SURGE BACK
INTO THE AREA ON SATURDAY...AHEAD OF THE MORE POTENT SHORTWAVE
TROUGH CROSSING SOUTH CENTRAL CANADA. ONLY HAVE SOME VERY LOW
CHANCES OF PRECIPITATION IN...MAINLY TOWARDS CENTRAL WISCONSIN WHERE
ISENTROPIC LIFT LOOKS GREATEST. BIGGEST CONCERN COMES SUNDAY AND
MONDAY WITH HOW MUCH COLD AIR COMES IN BEHIND THE COLD FRONT
ASSOCIATED WITH THE SHORTWAVE TROUGH...ALONG WITH TIMING TOO. 27.00Z
ECMWF IS VERY AGGRESSIVE DIVING 925MB TEMPS DOWN TO 6C BY 12Z
MONDAY. COMPARE THIS TO THE 27.00Z GFS WHICH ARE 16-20C...DRAMATIC
DIFFERENCE. THUS...TEMPERATURE FORECASTS ARE LOW CONFIDENCE. GIVEN
THE COOLER SIGNAL IN THE ECMWF...FELT IT WAS APPROPRIATE TO LOWER
HIGHS...LOWS AND DEWPOINTS FOR SUNDAY THROUGH MONDAY NIGHT ABOUT 5
OR SO DEGREES FROM THE PREVIOUS FORECAST. RAIN CHANCES LOOK MINIMAL
FOR SUNDAY THROUGH MONDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1239 PM CDT TUE AUG 27 2013
THE MAIN FOCUS AT THE TAF SITES IS WITH WHETHER ANY STORMS WILL
DEVELOP THIS AFTERNOON AHEAD OF A COLD FRONT...FOLLOWED BY THE
POTENTIAL FOR FOG TONIGHT. AN UNSTABLE ATMOSPHERE HAS DEVELOPED
AHEAD OF A COLD FRONT RUNNING EAST TO WEST FROM NORTHEAST
WISCONSIN TO CENTRAL MINNESOTA. THERE IS A CHANCE FOR CONVECTION
TO DEVELOP ALONG THE FRONT THIS AFTERNOON...MAINLY IN CENTRAL TO
EASTERN WISCONSIN AND AWAY FROM THE TAF SITES. HIGHER CONFIDENCE
EXISTS IN THE DEVELOPMENT OF FOG TONIGHT BEHIND THE COLD FRONT.
HUMIDITY LOOKS LIKE IT STAYS UP EVEN BEHIND THE FRONT WHILE
TEMPERATURES ARE DROPPING. WITH CLEAR SKIES AND LIGHT
WINDS...EXPECT THAT THIS COMBINATION WILL LEAD TO SOME FOG
DEVELOPMENT OVERNIGHT WITH CONDITIONS DROPPING TO IFR OR LOWER
BETWEEN 8-14Z.
&&
.CLIMATE...
ISSUED AT 334 PM CDT MON AUG 26 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR WIZ017-029-034-
042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR WIZ032-033-
041.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR MNZ086-087-094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR MNZ079-088-
096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR IAZ008>011-018-019-
029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...HALBACH
CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1222 PM CDT TUE AUG 27 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 336 AM CDT TUE AUG 27 2013
AREA RADARS CONTINUE TO SHOW STORMS FORM OVER MN AND MOVE INTO/
THROUGH NORTHERN WI. SO FAR STORMS HAVE NOT TRAINED OVER SAME
LOCATION WITH HEAVY RAIN FALLING IN NARROW BANDS. STORMS NOW OVER
NW WI...TO MOVE INTO CWA AFT 10Z. WILL NEED TO BE WATCHED AS SHEAR
INCREASING OVER NORTHERN WI ATTM. STORMS NOT EXPECTED INTO FFA AREA
UNTIL 12Z OR AFTER...SO HAVE DECIDED TO DROP HEADLINE. MAIN ISSUE
OF THIS FORECAST IS PCPN TRENDS.
FORCING FOR STORMS OVERNIGHT FGEN/WAA SHIFTING EAST WITH 850 WINDS
BECOMING WESTERLY BY MORNING. TODAYS FORCING TO BE MORE TIED INTO
RIDGE RIDING DISTURBANCES AND LOCATION OF BOUNDARY. MODELS SUGGEST
BOUNDARY TO SHIFT SLOWLY SOUTH THROUGH CWA TODAY. HRRR NOT DOING
TO BAD ATTM...WITH CURRENT PCPN NORTH. HRRR TRENDS TO DIMINISH
PCPN DURING MORNING HOURS...THEN REDEVELOP OVER REGION FROM
MARINETTE TO TOMAHAWK BY MID AFTERNOON. AGAIN AREA IN SLIGHT RISK
FOR SEVERE WITH SIG INSTABILITY.
HIGH PRESSURE TO BUILD INTO STATE LATER TONIGHT AND WED...BRINGING A
BRIEF DRYING TREND.
TEMPS TODAY AGAIN HIGHLY DEPENDENT ON CLOUDS. WINDS BECOME A BIT
MORE ONSHORE TOO AS BOUNDARY SHIFTS SOUTH. HAVE TRENDED A BIT
COOLER NORTH AND FAR EAST...STAYING CLOSE TO YESTERDAYS READINGS.
AGAIN HEAT INDEX READINGS HIT 100 FOR COUPLE HOURS FAR SOUTHWEST
CWA. WILL STAY WITH SPS TO HIGHLIGHT AND NOT ISSUE ANY HEADLINE.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 336 AM CDT TUE AUG 27 2013
MDLS ARE IN GENERAL AGREEMENT ON THE LONG-RANGE MEAN FLOW ACROSS
THE CONUS WITH UPR TROFS JUST OFF THE WEST COAST AND WRN ATLANTIC
WITH AN UPR RDG SITUATED OVER THE CNTRL/SRN PLAINS. QUESTIONS
ARISE BY LATE IN THE WEEKEND WHETHER THE UPR RDG WL REMAIN
SOMEWHAT FLAT OR BUILD NWD THRU THE ROCKIES AS AN UPR TROF DIGS
TOWARD THE NE CONUS. AFTER A BRIEF RESPITE FROM THE HEAT/HUMIDITY
WED NGT/THU...RETURN FLOW MAKES A COMEBACK BRINGING PCPN CHCS BACK
TO THE REGION THU NGT/FRI WITH SEVERAL OTHER CHCS FOR PCPN THRU
THE UPCOMING WEEKEND.
NE WI TO REMAIN ON THE WRN FRINGE OF THE SFC HI THRU WED NGT...
THEREBY KEEPING WINDS LIGHT AND LEADING TO THE POTENTIAL OF MORE
FOG. THE EXACT EXTENT OF THE FOG IS A BIT UNCERTAIN AS MID AND UPR
LEVEL CLOUDS COULD BE MOVING INTO CNTRL WI AFTER MIDNGT AS WAA
BEGINS TO SPREAD NE FROM THE MIDWEST. HAVE KEPT FOG PATCHY FOR NOW
WITH MIN TEMPS RANGING FROM THE UPR 50S TO LWR 60S NORTH...60 TO
65 DEGS ELSEWHERE.
AS THE SFC HI DRIFTS TOWARD THE ERN GREAT LAKES ON THU...RETURN
FLOW SETS UP ACROSS WI WITH DEW POINTS STARTING TO CREEP UP ONCE
AGAIN. IN ADDITION...MDLS ARE SHOWING A SHORTWAVE TROF TOPPING THE
UPR RDG AND SLIDING E-SE TOWARD THE WRN GREAT LAKES BY LATE IN THE
DAY. BETWEEN THE LIFT FROM THE WAA AND THE START OF MID-LEVEL
FORCING FROM THE SHORTWAVE TROF...CANNOT RULE OUT A FEW SHWRS OR
TSTMS OVER CNTRL WI DURING THE AFTERNOON. AWAY FROM THE IMMEDIATE
LAKESHORE...EXPECT MAX TEMPS TO GENERALLY REACH THE LWR TO MID 80S.
THE SHORTWAVE TROF IS FCST TO MOVE SE INTO THE GREAT LAKES REGION
THU NGT AND HELP TO DRAG A WEAK FRONTAL BOUNDARY INTO NRN WI DURING
THE OVRNGT HOURS. WHILE INSTABILITY IS MARGINAL...SHEAR IS FAIRLY
STRONG TO SUSTAIN UPDRAFTS AND THERE IS A DIFFLUENT FLOW ALOFT
ADDING TO THE LIFT. PREFER TO GO WITH A MORE UNIFORM HI CHC POP
FOR NE WI...BUT BELIEVE THAT NRN PARTS OF THE STATE WOULD SEE
HIGHER QPF AMOUNTS AS FORCING A BIT STRONGER DUE TO THE PROXIMITY
OF THE SHORTWAVE TROF. THIS FRONTAL BOUNDARY WL SLOWLY SAG THRU WI
ON FRI...BUT BEGIN TO SLOW DOWN AS IT ENCOUNTERS THE EDGE OF THE
BROAD CNTRL/SRN PLAINS UPR RDG. A CONTINUED CHC OF SHWRS/TSTMS
ACROSS THE FCST AREA IS NECESSARY...ALTHO THE NORTH MAY SEE THE
PCPN COME TO AN END DURING THE AFTERNOON IF THE BOUNDARY CAN SLIP
FAR ENUF TO THE SOUTH. ANTICIPATED CLOUDS SHOULD HELP TO HOLD
TEMPS IN CHECK...BUT WITH 8H TEMPS STILL NEAR +20C...ANOTHER DAY
IN THE LWR TO MID 80S CAN BE EXPECTED.
THE MAIN QUESTION FOR THE FRI NGT/SAT TIME FRAME IS WHETHER THIS
BOUNDARY WL PUSH FAR ENUF SOUTH BEFORE STALLING TO AVOID THE
MENTIONING OF MORE PCPN. MDLS HAVE VARIOUS SOLUTIONS HERE...BUT
THE LATEST TRENDS DO SHOW THIS BOUNDARY SAGGING FAR ENUF TO AT
LEAST MINIMIZE THE PCPN CHCS OVER THE NORTH. NOT ENUF CONFIDENCE
TO COMPLETELY PULL THE POPS...BUT AT LEAST WL ATTEMPT TO TIER POPS
MORE FROM SOUTH TO NORTH.
A LOT OF UNCERTAINTY REMAINS FOR THE SUNDAY PERIOD AS THE ECMWF
BUILDS THE UPR RDG NWD THRU THE ROCKIES FASTER THAN THE OTHER
MDLS. THE ECMWF`S SOLUTION WOULD SEND A CDFNT THRU WI ABOUT 12
HOURS FASTER...THUS CLEARING THINGS OUT FOR SUNDAY AS OPPOSED TO A
SUNDAY FROPA ADVERTISED BY THE GFS/GEM. SINCE THIS IS MAJOR
PATTERN CHANGE...FULLY EXPECT THE MDLS TO WAFFLE ON TIMING OF THIS
FROPA...THUS HAVE FOLLOWED THE CONSENSUS MDL SOLUTION WHICH KEEPS
A LOW POP IN THE FCST THRU SUNDAY. A LARGE AREA OF HI PRES IS THEN
FCST TO BUILD INTO THE REGION FOR MON AND BRING COOLER/MUCH DRIER
AIR TO NE WI.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1213 PM CDT TUE AUG 27 2013
COLD FRONT ACROSS NORTHERN WISCONSIN WILL SAG SOUTHWARD ACROSS THE
AREA THIS AFTERNOON INTO EARLY THIS EVENING. CONVECTION ALREADY HAS
BROKEN OUT ACROSS FAR NORTHEAST WISCONSIN...THE CENTRAL AND NORTHERN
BAY OF GREEN BAY AND UPPER MICHIGAN. STORMS WILL CONTINUE TO FIRE
ALONG COLD FRONT AS IT DROPS SOUTHWARD THIS AFTERNOON AND EVENING.
SOME OF THE STORMS COULD CONTAIN LARGE AND WIND GUSTS OVER 50 KNOTS.
FOR THE 18Z TAFS...TRIED TO TIME THE BEST CHANCES FOR STORMS FROM
18Z-22Z AT KRHI TO 23Z-02Z AT KATW AS THE CLUSTER OF STORMS IS EXPECTED
TO DROP SOUTHWARD. OVERNIGHT...LOOK FOR AT LEAST IFR CONDITIONS ACROSS
MUCH OF THE AREA. CONDITIONS COULD REACH AIRPORT MINIMUMS DUE TO LOW
CLOUDS AND FOG. ANY LOW CLOUDS AND FOG SHOULD GRADUALLY IMPROVE
WEDNESDAY MORNING AS HIGH PRESSURE BUILDS INTO THE STATE.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......KALLAS
AVIATION.......ECKBERG
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1209 PM CDT TUE AUG 27 2013
.UPDATE...ADDED THE REST OF THE FORECAST AREA TO THE HEAT
ADVISORY...IN EFFECT FROM NOON UNTIL 8 PM THIS EVENING. HRRR AND
WRF 4KM MODELS SHOWING SOUTHWEST WINDS PICKING UP DURING THE
AFTERNOON...WITH AN INCREASING PRESSURE GRADIENT. SOME GUSTS UP
TO 20 KNOTS OR SO ARE EXPECTED. THIS SHOULD HELP TEMPERATURES RISE
QUICKLY INTO THE LOWER TO MID 90S IN MOST OF THE AREA THIS
AFTERNOON. DEW POINTS POOLING IN THE LOWER 70S NEAR THE ADVANCING
COLD FRONT LATER THIS AFTERNOON SHOULD PREVENT MIX OUT OF THE DEW
POINTS.
THUS...HEAT INDEX VALUES OF AROUND 100 TO 105 ARE EXPECTED. SOME
AREAS RIGHT ALONG THE LAKESHORE MAY EXPERIENCE COOLER TEMPERATURES
WITH SOUTH SOUTHEAST WINDS AT TIMES...BUT SOUTHWEST WINDS AND THE
HOT HUMID CONDITIONS SHOULD LINGER ACROSS MOST OF THE AREA.
REMOVED THUNDER CHANCES FROM FORECAST IN THE FAR NORTH AND
NORTHEAST UNTIL LATER THIS AFTERNOON...AS THE COLD FRONT SHIFTS
SOUTHWARD TOWARD THE AREA. HRRR AND WRF 4KM MODELS BRING THE FRONT
THROUGH THE AREA BETWEEN 22Z TUESDAY AND 03Z WEDNESDAY. THESE
MODELS ARE SHOWING A MAINLY DRY FRONTAL PASSAGE. UPWARD VERTICAL
MOTION WITH THE FRONT IS SOMEWHAT WEAK...WITH THE NAM TOO
AGGRESSIVE WITH LOW LEVEL FRONTOGENESIS RESPONSE.
500MB VORTICITY MAXIMUM OVER EAST CENTRAL MINNESOTA IS EXPECTED TO
SLIDE SOUTHEAST THROUGH CENTRAL TO SOUTHEAST WISCONSIN DURING THE
AFTERNOON AND EARLY EVENING. ADJUSTED AREA FORECAST SOUNDINGS
SHOWING CAP MIXING OUT BY 21Z TO 22Z TUESDAY...WITH 1000 TO 1500
J/KG MEAN LAYER CAPE AND DEEP LAYER SHEAR OF 30 TO 35 KNOTS. SOME
INDICATION FOR ROTATING STORMS PER SPC SSEO PAGE AS WELL. IF
CONVECTION DOES DEVELOP...SEVERE STORMS ARE POSSIBLE GIVEN THESE
PARAMETERS...WITH STRONG WINDS AND LARGE HAIL THE MAIN HAZARDS.
FOR NOW...GIVEN SOME UNCERTAINTY WITH HOW MUCH CONVECTION WILL
FORM...CONTINUED CHANCE POPS IN THE NORTH AND EAST...CLOSEST TO
THE PASSING 500MB VORTICITY MAXIMUM.
&&
.AVIATION/18Z TAFS/...PREVAILING VFR CONDITIONS EXPECTED THIS
AFTERNOON AND THIS EVENING...WITH MVFR/IFR VISIBILITIES POSSIBLE
IN ANY STORMS WITH PASSING COLD FRONT. FOG WITH MVFR/IFR
VISIBILITIES POSSIBLE BETWEEN 06Z AND 14Z WEDNESDAY. VFR
CONDITIONS RETURN FOR THE REST OF WEDNESDAY...AS HIGH PRESSURE
MOVES INTO THE REGION.
SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE BETWEEN 22Z
TUESDAY AND 03Z WEDNESDAY AT TAF SITES...BEST CHANCES AT THE
EASTERN SITES. SOME UNCERTAINTY IF STORMS WILL FORM AND HOW
WIDESPREAD THEY WILL BE...SO WILL LEAVE VICINITY WORDING IN
EASTERN SITES FOR NOW. MVFR/IFR VISIBILITIES POSSIBLE WITH ANY
STORMS...ALONG WITH GUSTY WINDS AND HAIL.
GUSTY SOUTHWEST WINDS ARE EXPECTED THIS AFTERNOON INTO EARLY THIS
EVENING...BEFORE COLD FRONT PUSHES SOUTH THROUGH THE AREA BETWEEN
00Z AND 03Z WEDNESDAY. MODERATE WINDS SHIFT TO THE NORTH
NORTHEAST BEHIND THE FRONT...THEN BECOME LIGHT AND REMAIN NORTH
NORTHEAST THROUGH WEDNESDAY.
&&
.MARINE...PATCHY FOG SEEN ON WEB CAMERAS AT SHEBOYGAN AND MAINLY
AT PORT WASHINGTON...WITH MOIST AIRMASS OVER COOL SHORELINE
WATERS. INCREASING SOUTH WINDS SHOULD HELP MIX OUT THIS FOG BY
EARLY THIS AFTERNOON.
KEPT CHANCE WORDING FOR SHOWERS AND THUNDERSTORMS LATE THIS
AFTERNOON AND EARLY THIS EVENING. SOME UNCERTAINTY WITH IF AND HOW
WIDESPREAD STORMS WILL BE...GIVEN WEAK COLD FRONT MOVING THROUGH.
SEVERE STORMS WITH STRONG WINDS AND LARGE HAIL ARE POSSIBLE IF
ANY STORMS DO DEVELOP.
&&
.PREV DISCUSSION... /ISSUED 310 AM CDT TUE AUG 27 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM.
THE TWO MAIN ISSUES FOR TODAY INTO TONIGHT WILL BE THE HEAT AND THE
POTENTIAL FOR THUNDERSTORMS...WITH SOME POSSIBLY SEVERE.
CONVECTION TO OUR NORTH/NORTHEAST EARLY THIS MORNING WILL TRACK OFF
TO THE SOUTHEAST BY SUNRISE WITH THINGS LOOKING DRY INTO THE EARLY
AFTERNOON. THIS SHOULD GIVE THE CONVECTIVE DEBRIS PLENTY OF TIME TO
CLEAR OUT AND TEMPS TO RECOVER. AN IMPRESSIVE 925MB THERMAL RIDGE
IS PROGD TO PEAK OUT AROUND 28-29C ACROSS THE SOUTH BY LATE
AFTERNOON. THIS IS A FEW DEGREES HIGHER THAN YESTERDAY. DEW POINTS
SHOULD BE IN THE LOWER 70S AND THE COMBO STILL GIVES US HEAT INDICES
OF AROUND 100 ACROSS THE CURRENT HEAT ADVISORY AREA. THE NORTHEAST
FORECAST AREA SHOULD BE A FEW DEGREES COOLER DUE TO THE PROXIMITY TO
THE EARLY CONVECTION AND THE SUPPRESSED BAROCLINIC ZONE IN THAT AREA.
A COLD FRONT CURRENTLY STRETCHING FROM CENTRAL MN INTO NORTHERN
WISCONSIN WILL SAG TO ABOUT A TWIN CITIES TO GRB LINE BY 18Z...THEN
REACHING OUR NORTHERN CWA BY 00Z...AND SOUTH OF THE AREA BY AROUND
06Z. A MID LEVEL SHORT WAVE WILL BE ROUNDING THE TOP OF THE
RIDGE...MOVING THROUGH THE AREA DURING THE LATE AFTERNOON AND
EVENING. CAPES ARE EXPECTED TO CLIMB TO ABOUT 2500J/KG THIS
AFTERNOON WITH DEEP LAYER 0-6KM SHEAR ON THE ORDER OF 40KTS. THINGS
SHOULD BE CAPPED OFF ACROSS THE SOUTHWEST CWA...BUT THE NORTHEAST
HALF...NOT SO MUCH. SOME OF THE HI RES MODELS SHOW POTENTIAL FOR
STRONG STORM DEVELOPMENT FROM ABOUT MID AFTERNOON INTO THE EVENING
AND SPC HAS OUTLOOKED THE NE HALF IN A SLIGHT RISK. WILL KEEP THE
CHCY POPS FOR NOW AS THERE IS PLENTY OF UNCERTAINTY. IN FACT...THE
GFS KEEPS MOST ACTIVITY NORTH AND EAST OF THE FORECAST AREA.
WILL DRY IT OUT AFTER 06Z TONIGHT WITH COOLER TEMPS COMING IN BEHIND
THE DEPARTING FRONT FOR WEDNESDAY.
WEDNESDAY - CONFIDENCE...MEDIUM
SURFACE/850 RIDGING TAKES HOLD AS FRONTAL BOUNDARY SAGS SOUTH. NNE
FLOW BRINGS ONLY SUBTLE RELIEF FROM THE HEAT AND HUMIDITY. 925 TEMPS
STILL PROGGD INTO THE LOW-MID 20S CELSIUS AND DEW POINTS PROGGED
INTO THE UPPER 60S TO LOW 70S. APPEARS THE MORE DRAMATIC RELIEF WILL
BE NEAR LAKE MICHIGAN WITH THE COOLER TEMPS MORE LIKELY THERE GIVEN
THE WIND TRAJECTORY OFF THE LAKE.
THURSDAY - CONFIDENCE...MEDIUM
LINGERING HIGH PRESSURE IN CONTROL WITH BETTER RETURN FLOW AND
RENEWED BAROCLINICITY ACROSS ERN IA/ERN MN AND PORTIONS OF WRN AND
NRN WI. HOTTEST AIRMASS ACROSS IA/MN.
THURSDAY NIGHT AND FRIDAY - CONFIDENCE...MEDIUM
BROADLY ANTICYCLONIC 500 MILLIBAR FLOW TRANSITIONS TO MORE OF AN
ACTIVE NW FLOW REGIME WITH SHORTWAVE ENERGY KNOCKING DOWN THE RIDGE.
IN ADDITION...WARM AIR ADVECTION KICKS IN. 850/925 THERMAL GRADIENT
TIGHT IN THE MORNING THEN THERMAL RIDGE BECOMES PREDOMINANT IN THE
AFTERNOON. TOASTY READINGS ONCE AGAIN WITH 925 TEMPS INTO THE 26-29C
RANGE DURING PEAK HEATING ONCE REMNANT CLOUD DEBRIS ERODES.
CONSENSUS AMONGST OFFICES WAS TO BOOST HIGHS. WILL MAINTAIN SOME
POPS INTO THE AFTERNOON WITH WEAK SHORTWAVE ACTIVITY IN THE FLOW AND
UNSTABLE AIRMASS WITH CAPES OVER 1K J/KG. SOME CONCERN THAT CAP IN
THE SW MAY HAVE A SAY WITH 700 TEMPS PUSHING 12C. GFS PRECIP FIELDS
MAY BE OVERDONE HOWEVER EVEN THE ECMWF IS HINTING AT AFTERNOON
DEVELOPMENT. CAP PRETTY WEAK ON BUFKIT SOUNDINGS. WITH SURFACE/850
FRONT PUSHING IN FROM THE NORTH LATER IN THE DAY AND INTO THE
EVENING HOURS ANY CAP WILL LIKELY ERODE WITH ENOUGH LOW LEVEL
FORCING COMING INTO PLAY.
SATURDAY - CONFIDENCE...MEDIUM
LINGERING BAROCLINICITY NECESSITATES A CONTINUATION OF POPS. STILL A
SWIFT UPPER FLOW WITH POTENTIAL FOR A SHORTWAVE TO AID IN VERTICAL
MOTION AS WELL.
SUNDAY AND LABOR DAY - CONFIDENCE...MEDIUM
MAIN FOCUS IS ON ARRIVAL OF COOLER AIRMASS. MAY NEED TO EXTEND
SMALL POPS INTO SUNDAY MORNING WITH FRONTAL TIMING UNCERTAIN BUT
FOR NOW WILL GO WITH DRY FORECAST BUT PREFERRED ECMWF KEEPS MAIN
FOCUS TO OUR SOUTH AND EAST AS THE MORNING WEARS ON. 00Z ECMWF
HAS MAINTAINED THE 12Z SOLUTION OF SHOWING A MORE AMPLIFIED UPPER
AIR PATTERN WITH COOL SURGE ARRIVING SUNDAY NIGHT. LABOR DAY HAS
THE POTENTIAL TO BE QUITE COOL ESPECIALLY LAKESIDE. AFTERNOON 925
TEMPS ARE RUNNING 11C IN THE EAST TO 15C IN THE WEST WITH A NORTH
OR NORTHEAST WIND. CONSENSUS WITH SURROUNDING OFFICES WAS TO GO
WITH THE COOLER HPC TEMPS VERSUS THE WARMER ALLBLEND SOLUTION.
AVIATION/12Z TAFS/...GENERALLY LOOKING AT VFR CONDITIONS THROUGH THIS
EVENING. A COLD FRONT WILL BE APPROACHING FROM THE NORTH LATER
THIS AFTERNOON AND EVENING. THIS FRONT COULD BE THE FOCUS FOR
STRONG TO SEVERE STORMS...MAINLY FOR THE KMKE/KENW/KUES TAF SITES.
OUT TOWARD KMSN...THINGS MAY BE CAPPED OFF WITH LITTLE RISK OF
THUNDERSTORMS WITH THE FRONTAL PASSAGE. CONSISTENT WITH
THUNDERSTORMS...WE COULD SEE A BRIEF PERIOD OF MVFR CONDITIONS AS
STORMS MOVE THROUGH. FROPA AT MADISON IS EXPECTED AROUND 05Z AND
MILWAUKEE ABOUT 07Z.
IT APPEARS WE COULD SEE SOME MVFR CIGS/VSBYS ARRIVE BEHIND THE FRONT
LATE TONIGHT DUE TO WEAK COLD ADVECTION AND THE POSSIBILITY OF WINDS
TURNING ONSHORE ALONG LAKE MICHIGAN.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR WIZ046-047-051-052-
056>060-062>072.
LM...NONE.
&&
$$
UPDATE...WOOD
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
WEDNESDAY THROUGH MONDAY...COLLAR
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
644 AM CDT TUE AUG 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM CDT TUE AUG 27 2013
..CURRENTLY AS OF 08Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED AN UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUE TO ROTATE AROUND THE RIDGE...TRACKING FROM ARIZONA INTO THE
DAKOTAS AND THE FORECAST AREA. PRECIPITABLE WATER VALUES MAX OUT IN
THE 2-2.25 INCH RANGE FROM CENTRAL MN INTO NORTHERN WI PER RAP
ANALYSIS. CLUSTERS OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
MONSOONAL SHORTWAVES AS WELL AS 850MB-700MB MOISTURE TRANSPORT HAVE
BEEN TRACKING THROUGH THIS PRECIPITABLE WATER MAX. BLOWOFF FROM THIS
CONVECTION ENCOMPASSES MUCH OF THE FORECAST AREA. AIRMASS IS VERY
WARM ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. THE 00Z MPX RAOB
REPORTED A 25C 850MB TEMP AND 27C 925MB TEMP...WHICH TRANSLATED TO A
HIGH YESTERDAY OF 97F AT MSP. BETWEEN THE HOT TEMPERATURES
YESTERDAY...THE BLOWOFF...A LIGHT SOUTHERLY BREEZE AND DEWPOINTS
HOLDING IN THE LOW 70S...TEMPERATURES HAVE STRUGGLED TO DROP THIS
MORNING. READINGS ARE STILL MAINLY BETWEEN 75 AND 80. SURFACE
PRESSURE ANALYSIS SHOWED LOW PRESSURE NEAR MONTEVIDEO MN...WITH A
WARM FRONT STRETCHING INTO TAYLOR COUNTY AND A COLD FRONT BACK INTO
CHAMBERLAIN SOUTH DAKOTA.
..HAZARDS..
1. HEAT. HAVE KEPT ALL GOING HAZARDS INTACT. CONSIDERED UPGRADING
FLOYD...CHICKASAW AND FAYETTE COUNTIES TO EXCESSIVE HEAT
WARNING...BUT HEAT INDICES APPEAR MARGINAL TO DO SO.
2. STORMS. SEVERE POTENTIAL...PARTICULARLY THIS AFTERNOON NORTH AND
EAST OF I-94.
3. FOG LATE TONIGHT...WHICH COULD END UP BEING DENSE...ESPECIALLY
WHERE IT RAINS.
..SYNOPTIC OVERVIEW..
THE SUBTROPICAL RIDGE OVER KANSAS AND MISSOURI IS PROGGED TO STAY
PUT THROUGH TONIGHT. HOWEVER...A CHANGE IN THE UPPER AIR PATTERN IS
TO HAVE SOME RIDGE BUILD NORTH TONIGHT INTO THE DAKOTAS. THIS...IN
TURN...HELPS TO TURN THE FLOW MORE NORTHWESTERLY OVER THE FORECAST
AREA. A SERIES OF MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE ARE
FORECAST TO COME THROUGH NORTHEASTERN PORTIONS OF THE FORECAST AREA
THROUGH TONIGHT...HELPING TO PUSH THE SURFACE LOW AND COLD FRONT
SOUTHEAST THROUGH THE ENTIRE AREA BY 12Z WEDNESDAY.
..DETAILS..
PRECIPITATION...WITH 850MB AND 700MB MOISTURE TRANSPORT FOCUSED INTO
THE AREA NORTHEAST OF I-94 THIS MORNING...THERE REMAINS POTENTIAL
FOR CONVECTION JUST FROM THIS THERMODYNAMIC FORCING. HOWEVER...THINK
THE GREATER POTENTIAL FOR CONVECTION WILL COME THIS AFTERNOON AS A
SHORTWAVE PRESENTLY WEST OF FARGO COMES THROUGH CENTRAL WISCONSIN AT
PEAK HEATING. VERY GOOD MODEL CONSENSUS FOR CONVECTION TO OCCUR
NORTHEAST OF I-94 IN THE AFTERNOON...WITH EVEN A POSSIBILITY OF IT
EXTENDING BACK TOWARDS LA CROSSE. THIS CONVECTION WILL SLIDE
SOUTHEAST OF THE AREA DURING THE EVENING...WITH ALL OF IT LIKELY OUT
BY 03Z. DRY CONDITIONS ARE EXPECTED ELSEWHERE DUE TO CAPPING AND
LIMITED CONVERGENCE ON THE COLD FRONT...AND DRY CONDITIONS ARE
ANTICIPATED ONCE THE FRONT PASSES AS SUBSIDENCE AND DRYING WORK IN.
SEVERE POTENTIAL...0-6KM SHEAR IS DECENT IN THE MORNING...35-45 KT
NORTHEAST OF I-94. HOWEVER...NOT ANTICIPATING MUCH OF THE MORNING
CONVECTION TO BE ABLE TO UTILIZE THIS SHEAR. DURING THE AFTERNOON
WHEN CAPE IS AT ITS HIGHEST...THE 0-6KM SHEAR IS WEAKENING TO 30-35
KT. NONETHELESS...WITH MLCAPES OF 2000-2500 FT COMBINING WITH THIS
SHEAR SHOULD ALLOW FOR SOME STORM ORGANIZATION...LIKELY IN THE FORM
OF MULTICELLS WITH A SUPERCELL POSSIBLE. FREEZING LEVELS UP NEAR
16000 FT SHOULD LIMIT HAIL...BUT CERTAINLY DAMAGING WINDS AND VERY
HEAVY RAIN ARE POSSIBLE GIVEN THE UNSEASONABLY WARM...MOIST
ENVIRONMENT.
HEAT...925MB TEMPERATURES TODAY ARE PROGGED VERY SIMILAR TO
YESTERDAY AHEAD OF THE COLD FRONTAL PASSAGE...RUNNING BETWEEN
27-29C. SO WE SHOULD SEE READINGS THAT ARE SIMILAR AS WELL. AROUND
CHARLES CITY THE READINGS APPROACH 30C...SO IT IS POSSIBLE THEY WILL
END UP A LITTLE WARMER.
LASTLY...A POTENTIAL ISSUE TO DEAL WITH LATE IN THE NIGHT IS FOG.
THE FRONT THAT COMES THROUGH TONIGHT IS QUITE SHALLOW AND STRUGGLES
TO GET THESE HIGHER DEWPOINTS OUT OF HERE. WITH COOLER AIR COMING IN
BEHIND THE FRONT AND LIGHT SURFACE WINDS...WE MAY END UP WITH SOME
SHALLOW FOG...PARTICULARLY SOUTHWEST OF I-94. SREF VISIBILITY PROGS
SHOW THIS NICELY. HAVE RAISED THE FOG COVERAGE AND WILL HAVE TO
WATCH FOR POSSIBLE DENSE FOG.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 316 AM CDT TUE AUG 27 2013
..HAZARDS..
1. HEAT. DEWPOINTS LOOK A LITTLE BIT HIGHER FOR WEDNESDAY...THOUGH
TEMPERATURES WILL NOT BE NEARLY AS WARM THE PAST FEW DAYS.
THEREFORE...HEAT INDICES ONLY TOP OUT IN THE 90S...JUST BELOW
ADVISORY CRITERIA. FARTHER AHEAD...AN ADVISORY IS LOOKING MORE
LIKELY FOR FRIDAY...PARTICULARLY NORTHEAST IOWA AND FAR SOUTHWEST
WI. NO ADVISORIES NEEDED NOW FOR THE WEEKEND.
..SYNOPTIC OVERVIEW..
27.00Z MODEL GUIDANCE IN GOOD AGREEMENT SHOWING THAT THE SUBTROPICAL
RIDGE OVER KANSAS AND MISSOURI WILL RETROGRADE WESTWARD INTO THE
FOUR CORNERS REGION BY SATURDAY. THE LAST COUPLE OF DAYS MODELS HAD
SUGGESTED THAT THE RIDGE WOULD HEAD BACK EAST. HOWEVER...THIS IS NOW
DELAYED BECAUSE OF A SHORTWAVE TROUGH COMING OUT OF SOUTHWEST CANADA
ON FRIDAY THAT ENDS UP DIGGING INTO THE GREAT LAKES REGION ON
SUNDAY. THE 26.00Z ECMWF WAS FIRST TO SHOW THIS AND NOW ALL MODELS
HAVE CAPTURED ONTO THE IDEA. THE ONLY QUESTION NOW IS TIMING AND
AMPLIFICATION OF THIS TROUGH...WHICH THERE IS A DECENT SPREAD ON
COME SUNDAY.
..DETAILS..
WITH THE FRONTAL BOUNDARY SOUTH OF THE AREA ON WEDNESDAY AND HIGH
PRESSURE IN PLACE...HAVE CONTINUED THE DRY FORECAST. AS MENTIONED IN
THE HAZARDS SECTION...HIGHER DEWPOINTS DOES RAISE CONCERN FOR
EXTENSION IN THE HEAT ADVISORY. HOWEVER...925MB TEMPS OF 25-27C WILL
RESULT IN COOLER HIGHS...KEEPING HEAT INDICES BELOW ADVISORY LEVEL.
A SERIES OF SHORTWAVES ARE PROGGED TO COME ACROSS THE NORTHERN
PLAINS AND INTO THE NORTHERN GREAT LAKES REGION WEDNESDAY NIGHT
THROUGH FRIDAY. THE SHORTWAVES WEDNESDAY NIGHT AND THURSDAY ARE
PROGGED TO HELP BRING THE COLD FRONT BACK TOWARDS US...AND
ISENTROPIC LIFT/MOISTURE TRANSPORT OVER THE FRONT RESULTS IN CONCERN
FOR CONVECTION. THE GREATEST CHANCES FOR CONVECTION WEDNESDAY NIGHT
AND THURSDAY WILL TRACK JUST NORTH OF THE AREA...CLOSER TO THE
SHORTWAVES...BUT THE ISENTROPIC LIFT COULD SPREAD SOME SHOWERS AND
THUNDERSTORMS DOWN INTO THE FORECAST AREA...ESPECIALLY WEST OF THE
MS RIVER AND OVER NORTH CENTRAL WISCONSIN. HAVE CONTINUED 20-30
PERCENT CHANCES. THESE CHANCES GRADUALLY ENCOMPASS MORE OF THE AREA
HEADING INTO THURSDAY NIGHT AND ESPECIALLY FRIDAY. ON FRIDAY...
MODELS ARE IN GOOD AGREEMENT SHOWING A SHORTWAVE COMING THROUGH
CENTRAL MN AND SOUTHEAST INTO THE FORECAST AREA AT THE TIME OF PEAK
HEATING. 0-6KM SHEAR ONLY PROGGED 20-25 KT...SO NOT THINKING SEVERE
AT THIS TIME. TEMPERATURES WILL COOL DOWN BRIEFLY ON THURSDAY
BETWEEN CLOUDS/POTENTIAL CONVECTION AND 925MB TEMPS OF 22-26C.
HOWEVER...TEMPERATURES LOOK TO SHOOT BACK UP ON FRIDAY AHEAD OF THAT
SHORTWAVE COMING THROUGH. COOLING WILL OCCUR FRIDAY NIGHT WITH
PASSAGE OF THE SHORTWAVE TROUGH.
HEADING INTO LABOR DAY WEEKEND...WARM AIR COULD TRY TO SURGE BACK
INTO THE AREA ON SATURDAY...AHEAD OF THE MORE POTENT SHORTWAVE
TROUGH CROSSING SOUTH CENTRAL CANADA. ONLY HAVE SOME VERY LOW
CHANCES OF PRECIPITATION IN...MAINLY TOWARDS CENTRAL WISCONSIN WHERE
ISENTROPIC LIFT LOOKS GREATEST. BIGGEST CONCERN COMES SUNDAY AND
MONDAY WITH HOW MUCH COLD AIR COMES IN BEHIND THE COLD FRONT
ASSOCIATED WITH THE SHORTWAVE TROUGH...ALONG WITH TIMING TOO. 27.00Z
ECMWF IS VERY AGGRESSIVE DIVING 925MB TEMPS DOWN TO 6C BY 12Z
MONDAY. COMPARE THIS TO THE 27.00Z GFS WHICH ARE 16-20C...DRAMATIC
DIFFERENCE. THUS...TEMPERATURE FORECASTS ARE LOW CONFIDENCE. GIVEN
THE COOLER SIGNAL IN THE ECMWF...FELT IT WAS APPROPRIATE TO LOWER
HIGHS...LOWS AND DEWPOINTS FOR SUNDAY THROUGH MONDAY NIGHT ABOUT 5
OR SO DEGREES FROM THE PREVIOUS FORECAST. RAIN CHANCES LOOK MINIMAL
FOR SUNDAY THROUGH MONDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 642 AM CDT TUE AUG 27 2013
A COLD FRONT WILL PROVIDE A CHANCE OF SHOWERS AND THUNDERSTORMS
GENERALLY NORTH AND EAST OF INTERSTATE 94. AS A RESULT...DID NOT
INCLUDE THESE IN EITHER TAF SITE. SOUTHWEST WINDS OF AROUND
10 KNOTS WILL SHIFT TO WEST AROUND 27.23Z...AND THEN BECOME
NORTHWEST AND DECREASE TO AROUND 5 KNOTS AFTER 28.03Z.
FOR THE PAST 3 DAYS...THE SREF HAS INDICATED THAT WIDESPREAD FOG
WILL DEVELOP ACROSS THE AREA. SOME OF MOS VALUES INDICATE THAT
THIS FOG MAY BECOME DENSE. HOWEVER LIGHT NORTHEAST AND EAST WINDS
ALOFT ARE NORMALLY NOT THAT FAVORABLE FOR DENSE FOG. AS A RESULT...
JUST LOWERED IT DOWN TO 1 MILE AT THIS TIME.
&&
.CLIMATE...
ISSUED AT 334 PM CDT MON AUG 26 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR WIZ017-029-034-
042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR WIZ032-033-
041.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR MNZ086-087-094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR MNZ079-088-
096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR IAZ008>011-018-019-
029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
634 AM CDT TUE AUG 27 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 336 AM CDT TUE AUG 27 2013
AREA RADARS CONTINUE TO SHOW STORMS FORM OVER MN AND MOVE INTO/
THROUGH NORTHERN WI. SO FAR STORMS HAVE NOT TRAINED OVER SAME
LOCATION WITH HEAVY RAIN FALLING IN NARROW BANDS. STORMS NOW OVER
NW WI...TO MOVE INTO CWA AFT 10Z. WILL NEED TO BE WATCHED AS SHEAR
INCREASING OVER NORTHERN WI ATTM. STORMS NOT EXPECTED INTO FFA AREA
UNTIL 12Z OR AFTER...SO HAVE DECIDED TO DROP HEADLINE. MAIN ISSUE
OF THIS FORECAST IS PCPN TRENDS.
FORCING FOR STORMS OVERNIGHT FGEN/WAA SHIFTING EAST WITH 850 WINDS
BECOMING WESTERLY BY MORNING. TODAYS FORCING TO BE MORE TIED INTO
RIDGE RIDING DISTURBANCES AND LOCATION OF BOUNDARY. MODELS SUGGEST
BOUNDARY TO SHIFT SLOWLY SOUTH THROUGH CWA TODAY. HRRR NOT DOING
TO BAD ATTM...WITH CURRENT PCPN NORTH. HRRR TRENDS TO DIMINISH
PCPN DURING MORNING HOURS...THEN REDEVELOP OVER REGION FROM
MARINETTE TO TOMAHAWK BY MID AFTERNOON. AGAIN AREA IN SLIGHT RISK
FOR SEVERE WITH SIG INSTABILITY.
HIGH PRESSURE TO BUILD INTO STATE LATER TONIGHT AND WED...BRINGING A
BRIEF DRYING TREND.
TEMPS TODAY AGAIN HIGHLY DEPENDENT ON CLOUDS. WINDS BECOME A BIT
MORE ONSHORE TOO AS BOUNDARY SHIFTS SOUTH. HAVE TRENDED A BIT
COOLER NORTH AND FAR EAST...STAYING CLOSE TO YESTERDAYS READINGS.
AGAIN HEAT INDEX READINGS HIT 100 FOR COUPLE HOURS FAR SOUTHWEST
CWA. WILL STAY WITH SPS TO HIGHLIGHT AND NOT ISSUE ANY HEADLINE.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 336 AM CDT TUE AUG 27 2013
MDLS ARE IN GENERAL AGREEMENT ON THE LONG-RANGE MEAN FLOW ACROSS
THE CONUS WITH UPR TROFS JUST OFF THE WEST COAST AND WRN ATLANTIC
WITH AN UPR RDG SITUATED OVER THE CNTRL/SRN PLAINS. QUESTIONS
ARISE BY LATE IN THE WEEKEND WHETHER THE UPR RDG WL REMAIN
SOMEWHAT FLAT OR BUILD NWD THRU THE ROCKIES AS AN UPR TROF DIGS
TOWARD THE NE CONUS. AFTER A BRIEF RESPITE FROM THE HEAT/HUMIDITY
WED NGT/THU...RETURN FLOW MAKES A COMEBACK BRINGING PCPN CHCS BACK
TO THE REGION THU NGT/FRI WITH SEVERAL OTHER CHCS FOR PCPN THRU
THE UPCOMING WEEKEND.
NE WI TO REMAIN ON THE WRN FRINGE OF THE SFC HI THRU WED NGT...
THEREBY KEEPING WINDS LIGHT AND LEADING TO THE POTENTIAL OF MORE
FOG. THE EXACT EXTENT OF THE FOG IS A BIT UNCERTAIN AS MID AND UPR
LEVEL CLOUDS COULD BE MOVING INTO CNTRL WI AFTER MIDNGT AS WAA
BEGINS TO SPREAD NE FROM THE MIDWEST. HAVE KEPT FOG PATCHY FOR NOW
WITH MIN TEMPS RANGING FROM THE UPR 50S TO LWR 60S NORTH...60 TO
65 DEGS ELSEWHERE.
AS THE SFC HI DRIFTS TOWARD THE ERN GREAT LAKES ON THU...RETURN
FLOW SETS UP ACROSS WI WITH DEW POINTS STARTING TO CREEP UP ONCE
AGAIN. IN ADDITION...MDLS ARE SHOWING A SHORTWAVE TROF TOPPING THE
UPR RDG AND SLIDING E-SE TOWARD THE WRN GREAT LAKES BY LATE IN THE
DAY. BETWEEN THE LIFT FROM THE WAA AND THE START OF MID-LEVEL
FORCING FROM THE SHORTWAVE TROF...CANNOT RULE OUT A FEW SHWRS OR
TSTMS OVER CNTRL WI DURING THE AFTERNOON. AWAY FROM THE IMMEDIATE
LAKESHORE...EXPECT MAX TEMPS TO GENERALLY REACH THE LWR TO MID 80S.
THE SHORTWAVE TROF IS FCST TO MOVE SE INTO THE GREAT LAKES REGION
THU NGT AND HELP TO DRAG A WEAK FRONTAL BOUNDARY INTO NRN WI DURING
THE OVRNGT HOURS. WHILE INSTABILITY IS MARGINAL...SHEAR IS FAIRLY
STRONG TO SUSTAIN UPDRAFTS AND THERE IS A DIFFLUENT FLOW ALOFT
ADDING TO THE LIFT. PREFER TO GO WITH A MORE UNIFORM HI CHC POP
FOR NE WI...BUT BELIEVE THAT NRN PARTS OF THE STATE WOULD SEE
HIGHER QPF AMOUNTS AS FORCING A BIT STRONGER DUE TO THE PROXIMITY
OF THE SHORTWAVE TROF. THIS FRONTAL BOUNDARY WL SLOWLY SAG THRU WI
ON FRI...BUT BEGIN TO SLOW DOWN AS IT ENCOUNTERS THE EDGE OF THE
BROAD CNTRL/SRN PLAINS UPR RDG. A CONTINUED CHC OF SHWRS/TSTMS
ACROSS THE FCST AREA IS NECESSARY...ALTHO THE NORTH MAY SEE THE
PCPN COME TO AN END DURING THE AFTERNOON IF THE BOUNDARY CAN SLIP
FAR ENUF TO THE SOUTH. ANTICIPATED CLOUDS SHOULD HELP TO HOLD
TEMPS IN CHECK...BUT WITH 8H TEMPS STILL NEAR +20C...ANOTHER DAY
IN THE LWR TO MID 80S CAN BE EXPECTED.
THE MAIN QUESTION FOR THE FRI NGT/SAT TIME FRAME IS WHETHER THIS
BOUNDARY WL PUSH FAR ENUF SOUTH BEFORE STALLING TO AVOID THE
MENTIONING OF MORE PCPN. MDLS HAVE VARIOUS SOLUTIONS HERE...BUT
THE LATEST TRENDS DO SHOW THIS BOUNDARY SAGGING FAR ENUF TO AT
LEAST MINIMIZE THE PCPN CHCS OVER THE NORTH. NOT ENUF CONFIDENCE
TO COMPLETELY PULL THE POPS...BUT AT LEAST WL ATTEMPT TO TIER POPS
MORE FROM SOUTH TO NORTH.
A LOT OF UNCERTAINTY REMAINS FOR THE SUNDAY PERIOD AS THE ECMWF
BUILDS THE UPR RDG NWD THRU THE ROCKIES FASTER THAN THE OTHER
MDLS. THE ECMWF`S SOLUTION WOULD SEND A CDFNT THRU WI ABOUT 12
HOURS FASTER...THUS CLEARING THINGS OUT FOR SUNDAY AS OPPOSED TO A
SUNDAY FROPA ADVERTISED BY THE GFS/GEM. SINCE THIS IS MAJOR
PATTERN CHANGE...FULLY EXPECT THE MDLS TO WAFFLE ON TIMING OF THIS
FROPA...THUS HAVE FOLLOWED THE CONSENSUS MDL SOLUTION WHICH KEEPS
A LOW POP IN THE FCST THRU SUNDAY. A LARGE AREA OF HI PRES IS THEN
FCST TO BUILD INTO THE REGION FOR MON AND BRING COOLER/MUCH DRIER
AIR TO NE WI.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 627 AM CDT TUE AUG 27 2013
MAIN ISSUE IS TIMING AND LOCATION OF THUNDERSTORMS. AFTER MORNING
STORMS EXIT...EXPECT LULL WITH NEW STORMS DEVELOPING FOR THIS
AFTERNOON IN VCNTY OF SFC BOUNDARY EXPECTED TO BE IN AREA BETWEEN
TOMAHAWK AND MARINETTE. BOUNDARY AND STORMS EXPECTED TO MOVE SOUTH
THROUGH REGION BY LATE EVENING. LINGERING MOISTURE AND LIGHT WINDS
TO LEAD TO FOG FORMATION LATE TONIGHT.&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......KALLAS
AVIATION.......TE
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 336 AM CDT TUE AUG 27 2013
AREA RADARS CONTINUE TO SHOW STORMS FORM OVER MN AND MOVE INTO/
THROUGH NORTHERN WI. SO FAR STORMS HAVE NOT TRAINED OVER SAME
LOCATION WITH HEAVY RAIN FALLING IN NARROW BANDS. STORMS NOW OVER
NW WI...TO MOVE INTO CWA AFT 10Z. WILL NEED TO BE WATCHED AS SHEAR
INCREASING OVER NORTHERN WI ATTM. STORMS NOT EXPECTED INTO FFA AREA
UNTIL 12Z OR AFTER...SO HAVE DECIDED TO DROP HEADLINE. MAIN ISSUE
OF THIS FORECAST IS PCPN TRENDS.
FORCING FOR STORMS OVERNIGHT FGEN/WAA SHIFTING EAST WITH 850 WINDS
BECOMING WESTERLY BY MORNING. TODAYS FORCING TO BE MORE TIED INTO
RIDGE RIDING DISTURBANCES AND LOCATION OF BOUNDARY. MODELS SUGGEST
BOUNDARY TO SHIFT SLOWLY SOUTH THROUGH CWA TODAY. HRRR NOT DOING
TO BAD ATTM...WITH CURRENT PCPN NORTH. HRRR TRENDS TO DIMINISH
PCPN DURING MORNING HOURS...THEN REDEVELOP OVER REGION FROM
MARINETTE TO TOMAHAWK BY MID AFTERNOON. AGAIN AREA IN SLIGHT RISK
FOR SEVERE WITH SIG INSTABILITY.
HIGH PRESSURE TO BUILD INTO STATE LATER TONIGHT AND WED...BRINGING A
BRIEF DRYING TREND.
TEMPS TODAY AGAIN HIGHLY DEPENDENT ON CLOUDS. WINDS BECOME A BIT
MORE ONSHORE TOO AS BOUNDARY SHIFTS SOUTH. HAVE TRENDED A BIT
COOLER NORTH AND FAR EAST...STAYING CLOSE TO YESTERDAYS READINGS.
AGAIN HEAT INDEX READINGS HIT 100 FOR COUPLE HOURS FAR SOUTHWEST
CWA. WILL STAY WITH SPS TO HIGHLIGHT AND NOT ISSUE ANY HEADLINE.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 336 AM CDT TUE AUG 27 2013
MDLS ARE IN GENERAL AGREEMENT ON THE LONG-RANGE MEAN FLOW ACROSS
THE CONUS WITH UPR TROFS JUST OFF THE WEST COAST AND WRN ATLANTIC
WITH AN UPR RDG SITUATED OVER THE CNTRL/SRN PLAINS. QUESTIONS
ARISE BY LATE IN THE WEEKEND WHETHER THE UPR RDG WL REMAIN
SOMEWHAT FLAT OR BUILD NWD THRU THE ROCKIES AS AN UPR TROF DIGS
TOWARD THE NE CONUS. AFTER A BRIEF RESPITE FROM THE HEAT/HUMIDITY
WED NGT/THU...RETURN FLOW MAKES A COMEBACK BRINGING PCPN CHCS BACK
TO THE REGION THU NGT/FRI WITH SEVERAL OTHER CHCS FOR PCPN THRU
THE UPCOMING WEEKEND.
NE WI TO REMAIN ON THE WRN FRINGE OF THE SFC HI THRU WED NGT...
THEREBY KEEPING WINDS LIGHT AND LEADING TO THE POTENTIAL OF MORE
FOG. THE EXACT EXTENT OF THE FOG IS A BIT UNCERTAIN AS MID AND UPR
LEVEL CLOUDS COULD BE MOVING INTO CNTRL WI AFTER MIDNGT AS WAA
BEGINS TO SPREAD NE FROM THE MIDWEST. HAVE KEPT FOG PATCHY FOR NOW
WITH MIN TEMPS RANGING FROM THE UPR 50S TO LWR 60S NORTH...60 TO
65 DEGS ELSEWHERE.
AS THE SFC HI DRIFTS TOWARD THE ERN GREAT LAKES ON THU...RETURN
FLOW SETS UP ACROSS WI WITH DEW POINTS STARTING TO CREEP UP ONCE
AGAIN. IN ADDITION...MDLS ARE SHOWING A SHORTWAVE TROF TOPPING THE
UPR RDG AND SLIDING E-SE TOWARD THE WRN GREAT LAKES BY LATE IN THE
DAY. BETWEEN THE LIFT FROM THE WAA AND THE START OF MID-LEVEL
FORCING FROM THE SHORTWAVE TROF...CANNOT RULE OUT A FEW SHWRS OR
TSTMS OVER CNTRL WI DURING THE AFTERNOON. AWAY FROM THE IMMEDIATE
LAKESHORE...EXPECT MAX TEMPS TO GENERALLY REACH THE LWR TO MID 80S.
THE SHORTWAVE TROF IS FCST TO MOVE SE INTO THE GREAT LAKES REGION
THU NGT AND HELP TO DRAG A WEAK FRONTAL BOUNDARY INTO NRN WI DURING
THE OVRNGT HOURS. WHILE INSTABILITY IS MARGINAL...SHEAR IS FAIRLY
STRONG TO SUSTAIN UPDRAFTS AND THERE IS A DIFFLUENT FLOW ALOFT
ADDING TO THE LIFT. PREFER TO GO WITH A MORE UNIFORM HI CHC POP
FOR NE WI...BUT BELIEVE THAT NRN PARTS OF THE STATE WOULD SEE
HIGHER QPF AMOUNTS AS FORCING A BIT STRONGER DUE TO THE PROXIMITY
OF THE SHORTWAVE TROF. THIS FRONTAL BOUNDARY WL SLOWLY SAG THRU WI
ON FRI...BUT BEGIN TO SLOW DOWN AS IT ENCOUNTERS THE EDGE OF THE
BROAD CNTRL/SRN PLAINS UPR RDG. A CONTINUED CHC OF SHWRS/TSTMS
ACROSS THE FCST AREA IS NECESSARY...ALTHO THE NORTH MAY SEE THE
PCPN COME TO AN END DURING THE AFTERNOON IF THE BOUNDARY CAN SLIP
FAR ENUF TO THE SOUTH. ANTICIPATED CLOUDS SHOULD HELP TO HOLD
TEMPS IN CHECK...BUT WITH 8H TEMPS STILL NEAR +20C...ANOTHER DAY
IN THE LWR TO MID 80S CAN BE EXPECTED.
THE MAIN QUESTION FOR THE FRI NGT/SAT TIME FRAME IS WHETHER THIS
BOUNDARY WL PUSH FAR ENUF SOUTH BEFORE STALLING TO AVOID THE
MENTIONING OF MORE PCPN. MDLS HAVE VARIOUS SOLUTIONS HERE...BUT
THE LATEST TRENDS DO SHOW THIS BOUNDARY SAGGING FAR ENUF TO AT
LEAST MINIMIZE THE PCPN CHCS OVER THE NORTH. NOT ENUF CONFIDENCE
TO COMPLETELY PULL THE POPS...BUT AT LEAST WL ATTEMPT TO TIER POPS
MORE FROM SOUTH TO NORTH.
A LOT OF UNCERTAINTY REMAINS FOR THE SUNDAY PERIOD AS THE ECMWF
BUILDS THE UPR RDG NWD THRU THE ROCKIES FASTER THAN THE OTHER
MDLS. THE ECMWF`S SOLUTION WOULD SEND A CDFNT THRU WI ABOUT 12
HOURS FASTER...THUS CLEARING THINGS OUT FOR SUNDAY AS OPPOSED TO A
SUNDAY FROPA ADVERTISED BY THE GFS/GEM. SINCE THIS IS MAJOR
PATTERN CHANGE...FULLY EXPECT THE MDLS TO WAFFLE ON TIMING OF THIS
FROPA...THUS HAVE FOLLOWED THE CONSENSUS MDL SOLUTION WHICH KEEPS
A LOW POP IN THE FCST THRU SUNDAY. A LARGE AREA OF HI PRES IS THEN
FCST TO BUILD INTO THE REGION FOR MON AND BRING COOLER/MUCH DRIER
AIR TO NE WI.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1049 PM CDT MON AUG 26 2013
MAINLY STRATIFORM TYPE PRECIPITATION WITH EMBEDDED
STORMS OVER NORTH CENTRAL WISCONSIN CONTINUES TO SPREAD SOUTHEAST
OVERNIGHT. SCATTERED MVFR CIGS AND VSBYS WITH SHOWERS AND STORMS
OVERNIGHT WITH PERHAPS POCKETS OF IFR CIGS LATE TONIGHT OVER NORTH
CENTRAL WISCONSIN. WITH THE FRONT STILL GRADUALLY DROPPING SOUTH
ON TUESDAY...SCATTERED MVFR CIGS AND VSBYS DUE TO CONVECTION WILL
CONTINUE.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......KALLAS
AVIATION.......TDH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
316 AM CDT TUE AUG 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM CDT TUE AUG 27 2013
..CURRENTLY AS OF 08Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED AN UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST AND STRONG SUBTROPICAL
RIDGING OVER KANSAS AND MISSOURI. MONSOONAL MOISTURE AND SHORTWAVES
CONTINUE TO ROTATE AROUND THE RIDGE...TRACKING FROM ARIZONA INTO THE
DAKOTAS AND THE FORECAST AREA. PRECIPITABLE WATER VALUES MAX OUT IN
THE 2-2.25 INCH RANGE FROM CENTRAL MN INTO NORTHERN WI PER RAP
ANALYSIS. CLUSTERS OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
MONSOONAL SHORTWAVES AS WELL AS 850MB-700MB MOISTURE TRANSPORT HAVE
BEEN TRACKING THROUGH THIS PRECIPITABLE WATER MAX. BLOWOFF FROM THIS
CONVECTION ENCOMPASSES MUCH OF THE FORECAST AREA. AIRMASS IS VERY
WARM ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. THE 00Z MPX RAOB
REPORTED A 25C 850MB TEMP AND 27C 925MB TEMP...WHICH TRANSLATED TO A
HIGH YESTERDAY OF 97F AT MSP. BETWEEN THE HOT TEMPERATURES
YESTERDAY...THE BLOWOFF...A LIGHT SOUTHERLY BREEZE AND DEWPOINTS
HOLDING IN THE LOW 70S...TEMPERATURES HAVE STRUGGLED TO DROP THIS
MORNING. READINGS ARE STILL MAINLY BETWEEN 75 AND 80. SURFACE
PRESSURE ANALYSIS SHOWED LOW PRESSURE NEAR MONTEVIDEO MN...WITH A
WARM FRONT STRETCHING INTO TAYLOR COUNTY AND A COLD FRONT BACK INTO
CHAMBERLAIN SOUTH DAKOTA.
..HAZARDS..
1. HEAT. HAVE KEPT ALL GOING HAZARDS INTACT. CONSIDERED UPGRADING
FLOYD...CHICKASAW AND FAYETTE COUNTIES TO EXCESSIVE HEAT
WARNING...BUT HEAT INDICES APPEAR MARGINAL TO DO SO.
2. STORMS. SEVERE POTENTIAL...PARTICULARLY THIS AFTERNOON NORTH AND
EAST OF I-94.
3. FOG LATE TONIGHT...WHICH COULD END UP BEING DENSE...ESPECIALLY
WHERE IT RAINS.
..SYNOPTIC OVERVIEW..
THE SUBTROPICAL RIDGE OVER KANSAS AND MISSOURI IS PROGGED TO STAY
PUT THROUGH TONIGHT. HOWEVER...A CHANGE IN THE UPPER AIR PATTERN IS
TO HAVE SOME RIDGE BUILD NORTH TONIGHT INTO THE DAKOTAS. THIS...IN
TURN...HELPS TO TURN THE FLOW MORE NORTHWESTERLY OVER THE FORECAST
AREA. A SERIES OF MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE ARE
FORECAST TO COME THROUGH NORTHEASTERN PORTIONS OF THE FORECAST AREA
THROUGH TONIGHT...HELPING TO PUSH THE SURFACE LOW AND COLD FRONT
SOUTHEAST THROUGH THE ENTIRE AREA BY 12Z WEDNESDAY.
..DETAILS..
PRECIPITATION...WITH 850MB AND 700MB MOISTURE TRANSPORT FOCUSED INTO
THE AREA NORTHEAST OF I-94 THIS MORNING...THERE REMAINS POTENTIAL
FOR CONVECTION JUST FROM THIS THERMODYNAMIC FORCING. HOWEVER...THINK
THE GREATER POTENTIAL FOR CONVECTION WILL COME THIS AFTERNOON AS A
SHORTWAVE PRESENTLY WEST OF FARGO COMES THROUGH CENTRAL WISCONSIN AT
PEAK HEATING. VERY GOOD MODEL CONSENSUS FOR CONVECTION TO OCCUR
NORTHEAST OF I-94 IN THE AFTERNOON...WITH EVEN A POSSIBILITY OF IT
EXTENDING BACK TOWARDS LA CROSSE. THIS CONVECTION WILL SLIDE
SOUTHEAST OF THE AREA DURING THE EVENING...WITH ALL OF IT LIKELY OUT
BY 03Z. DRY CONDITIONS ARE EXPECTED ELSEWHERE DUE TO CAPPING AND
LIMITED CONVERGENCE ON THE COLD FRONT...AND DRY CONDITIONS ARE
ANTICIPATED ONCE THE FRONT PASSES AS SUBSIDENCE AND DRYING WORK IN.
SEVERE POTENTIAL...0-6KM SHEAR IS DECENT IN THE MORNING...35-45 KT
NORTHEAST OF I-94. HOWEVER...NOT ANTICIPATING MUCH OF THE MORNING
CONVECTION TO BE ABLE TO UTILIZE THIS SHEAR. DURING THE AFTERNOON
WHEN CAPE IS AT ITS HIGHEST...THE 0-6KM SHEAR IS WEAKENING TO 30-35
KT. NONETHELESS...WITH MLCAPES OF 2000-2500 FT COMBINING WITH THIS
SHEAR SHOULD ALLOW FOR SOME STORM ORGANIZATION...LIKELY IN THE FORM
OF MULTICELLS WITH A SUPERCELL POSSIBLE. FREEZING LEVELS UP NEAR
16000 FT SHOULD LIMIT HAIL...BUT CERTAINLY DAMAGING WINDS AND VERY
HEAVY RAIN ARE POSSIBLE GIVEN THE UNSEASONABLY WARM...MOIST
ENVIRONMENT.
HEAT...925MB TEMPERATURES TODAY ARE PROGGED VERY SIMILAR TO
YESTERDAY AHEAD OF THE COLD FRONTAL PASSAGE...RUNNING BETWEEN
27-29C. SO WE SHOULD SEE READINGS THAT ARE SIMILAR AS WELL. AROUND
CHARLES CITY THE READINGS APPROACH 30C...SO IT IS POSSIBLE THEY WILL
END UP A LITTLE WARMER.
LASTLY...A POTENTIAL ISSUE TO DEAL WITH LATE IN THE NIGHT IS FOG.
THE FRONT THAT COMES THROUGH TONIGHT IS QUITE SHALLOW AND STRUGGLES
TO GET THESE HIGHER DEWPOINTS OUT OF HERE. WITH COOLER AIR COMING IN
BEHIND THE FRONT AND LIGHT SURFACE WINDS...WE MAY END UP WITH SOME
SHALLOW FOG...PARTICULARLY SOUTHWEST OF I-94. SREF VISIBILITY PROGS
SHOW THIS NICELY. HAVE RAISED THE FOG COVERAGE AND WILL HAVE TO
WATCH FOR POSSIBLE DENSE FOG.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 316 AM CDT TUE AUG 27 2013
..HAZARDS..
1. HEAT. DEWPOINTS LOOK A LITTLE BIT HIGHER FOR WEDNESDAY...THOUGH
TEMPERATURES WILL NOT BE NEARLY AS WARM THE PAST FEW DAYS.
THEREFORE...HEAT INDICES ONLY TOP OUT IN THE 90S...JUST BELOW
ADVISORY CRITERIA. FARTHER AHEAD...AN ADVISORY IS LOOKING MORE
LIKELY FOR FRIDAY...PARTICULARLY NORTHEAST IOWA AND FAR SOUTHWEST
WI. NO ADVISORIES NEEDED NOW FOR THE WEEKEND.
..SYNOPTIC OVERVIEW..
27.00Z MODEL GUIDANCE IN GOOD AGREEMENT SHOWING THAT THE SUBTROPICAL
RIDGE OVER KANSAS AND MISSOURI WILL RETROGRADE WESTWARD INTO THE
FOUR CORNERS REGION BY SATURDAY. THE LAST COUPLE OF DAYS MODELS HAD
SUGGESTED THAT THE RIDGE WOULD HEAD BACK EAST. HOWEVER...THIS IS NOW
DELAYED BECAUSE OF A SHORTWAVE TROUGH COMING OUT OF SOUTHWEST CANADA
ON FRIDAY THAT ENDS UP DIGGING INTO THE GREAT LAKES REGION ON
SUNDAY. THE 26.00Z ECMWF WAS FIRST TO SHOW THIS AND NOW ALL MODELS
HAVE CAPTURED ONTO THE IDEA. THE ONLY QUESTION NOW IS TIMING AND
AMPLIFICATION OF THIS TROUGH...WHICH THERE IS A DECENT SPREAD ON
COME SUNDAY.
..DETAILS..
WITH THE FRONTAL BOUNDARY SOUTH OF THE AREA ON WEDNESDAY AND HIGH
PRESSURE IN PLACE...HAVE CONTINUED THE DRY FORECAST. AS MENTIONED IN
THE HAZARDS SECTION...HIGHER DEWPOINTS DOES RAISE CONCERN FOR
EXTENSION IN THE HEAT ADVISORY. HOWEVER...925MB TEMPS OF 25-27C WILL
RESULT IN COOLER HIGHS...KEEPING HEAT INDICES BELOW ADVISORY LEVEL.
A SERIES OF SHORTWAVES ARE PROGGED TO COME ACROSS THE NORTHERN
PLAINS AND INTO THE NORTHERN GREAT LAKES REGION WEDNESDAY NIGHT
THROUGH FRIDAY. THE SHORTWAVES WEDNESDAY NIGHT AND THURSDAY ARE
PROGGED TO HELP BRING THE COLD FRONT BACK TOWARDS US...AND
ISENTROPIC LIFT/MOISTURE TRANSPORT OVER THE FRONT RESULTS IN CONCERN
FOR CONVECTION. THE GREATEST CHANCES FOR CONVECTION WEDNESDAY NIGHT
AND THURSDAY WILL TRACK JUST NORTH OF THE AREA...CLOSER TO THE
SHORTWAVES...BUT THE ISENTROPIC LIFT COULD SPREAD SOME SHOWERS AND
THUNDERSTORMS DOWN INTO THE FORECAST AREA...ESPECIALLY WEST OF THE
MS RIVER AND OVER NORTH CENTRAL WISCONSIN. HAVE CONTINUED 20-30
PERCENT CHANCES. THESE CHANCES GRADUALLY ENCOMPASS MORE OF THE AREA
HEADING INTO THURSDAY NIGHT AND ESPECIALLY FRIDAY. ON FRIDAY...
MODELS ARE IN GOOD AGREEMENT SHOWING A SHORTWAVE COMING THROUGH
CENTRAL MN AND SOUTHEAST INTO THE FORECAST AREA AT THE TIME OF PEAK
HEATING. 0-6KM SHEAR ONLY PROGGED 20-25 KT...SO NOT THINKING SEVERE
AT THIS TIME. TEMPERATURES WILL COOL DOWN BRIEFLY ON THURSDAY
BETWEEN CLOUDS/POTENTIAL CONVECTION AND 925MB TEMPS OF 22-26C.
HOWEVER...TEMPERATURES LOOK TO SHOOT BACK UP ON FRIDAY AHEAD OF THAT
SHORTWAVE COMING THROUGH. COOLING WILL OCCUR FRIDAY NIGHT WITH
PASSAGE OF THE SHORTWAVE TROUGH.
HEADING INTO LABOR DAY WEEKEND...WARM AIR COULD TRY TO SURGE BACK
INTO THE AREA ON SATURDAY...AHEAD OF THE MORE POTENT SHORTWAVE
TROUGH CROSSING SOUTH CENTRAL CANADA. ONLY HAVE SOME VERY LOW
CHANCES OF PRECIPITATION IN...MAINLY TOWARDS CENTRAL WISCONSIN WHERE
ISENTROPIC LIFT LOOKS GREATEST. BIGGEST CONCERN COMES SUNDAY AND
MONDAY WITH HOW MUCH COLD AIR COMES IN BEHIND THE COLD FRONT
ASSOCIATED WITH THE SHORTWAVE TROUGH...ALONG WITH TIMING TOO. 27.00Z
ECMWF IS VERY AGGRESSIVE DIVING 925MB TEMPS DOWN TO 6C BY 12Z
MONDAY. COMPARE THIS TO THE 27.00Z GFS WHICH ARE 16-20C...DRAMATIC
DIFFERENCE. THUS...TEMPERATURE FORECASTS ARE LOW CONFIDENCE. GIVEN
THE COOLER SIGNAL IN THE ECMWF...FELT IT WAS APPROPRIATE TO LOWER
HIGHS...LOWS AND DEWPOINTS FOR SUNDAY THROUGH MONDAY NIGHT ABOUT 5
OR SO DEGREES FROM THE PREVIOUS FORECAST. RAIN CHANCES LOOK MINIMAL
FOR SUNDAY THROUGH MONDAY NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1123 PM CDT MON AUG 26 2013
A WARM FRONT JUST NORTH OF THE I-94 CORRIDOR WILL KEEP KRST/KLSE
IN MORE OF A CAPPED ENVIRONMENT THROUGH TUESDAY...MEANING THAT
WARM AIR ALOFT SHOULD INHIBIT CONVECTION. VFR CONDITIONS EXPECTED AS A
RESULT WITH JUST SOME MID-LEVEL CLOUD COVER FROM CONVECTIVE
DEBRIS TO THE NORTH. OTHERWISE...SURFACE WINDS EXPECTED TO REMAIN
OUT OF THE SOUTH- SOUTHWEST AT 10-15KT WITH SOME LATE MORNING
THROUGH AFTERNOON GUSTINESS UP AROUND 20KT OR SO. A WEAK COLD
FRONT IS THEN EXPECTED TO SLIP INTO THE AREA TUESDAY EVENING. ANY
CONVECTION ASSOCIATED WITH THIS FRONTAL PASSAGE IS EXPECTED TO
REMAIN EAST OF THE MISSISSIPPI RIVER AND MAINLY ALONG AND NORTH OF
I-94. KLSE COULD GET BRUSHED BY SOME OF THIS SHRA/TS
ACTIVITY...BUT CONFIDENCE IS VERY LOW AT THIS POINT SO WILL LEAVE
OUT FOR NOW. OTHERWISE...LOOK FOR A WINDSHIFT FROM THE SOUTHWEST
TO THE NORTHWEST IN THE 23-01Z TIME FRAME AT KRST/KLSE. VFR
CONDITIONS ARE EXPECTED TO PREVAIL THROUGH TUESDAY EVENING.
&&
.CLIMATE...
ISSUED AT 334 PM CDT MON AUG 26 2013
THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER
THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE
CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON
THE HEAT.
LA CROSSE ROCHESTER
--------- ---------
TUE 8/27 95/1973 93/1984
WED 8/28 97/1955 96/1955
THU 8/29 95/1966 92/2012
FRI 8/30 97/2012 96/1941
SAT 8/31 95/1953 93/1960
SUN 9/1 98/1913 94/1937
MON 9/2 98/1937 94/1929
NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE
AND 76-78 AT ROCHESTER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR WIZ017-029-034-
042>044-053>055-061.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR WIZ032-033-
041.
MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR MNZ086-087-094-095.
EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR MNZ079-088-
096.
IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR IAZ008>011-018-019-
029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
334 PM MDT TUE AUG 27 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 330 PM MDT TUE AUG 27 2013
CURRENT KCYS RADAR LOOP SHOWS SOME SHALLOW CONVECTION DEVELOPING
OVER THE LARAMIE RANGE AND MOVING NORTHEAST INTO THE HIGH PLAINS
OF WYOMING THIS AFTERNOON. BELIEVE CONVECTION WILL BE MAINLY RAIN
SHOWERS WITH A FEW ISOLATED STRIKES OF LIGHTNING. THIS IS DUE TO
DRY AIR ALOFT MOVING THROUGH MOST OF THE FORECAST AREA
TODAY...WHICH IS DEPICTED WELL ON THE WATERVAPOR LOOP THIS
AFTERNOON. THIS DRY AIR ON THE WESTERN SIDE OF THE MAIN UPPER
LEVEL HIGH OVER KANSAS/MISSOURI WILL REMAIN OVER THE FORECAST AREA
THROUGH THURSDAY.
THE RIDGE AXIS EXTENDING NORTHEASTWARD FROM THE MAIN UPPER LEVEL
HIGH WILL PUSH ACROSS THE AREA ON WEDNESDAY. ALTHOUGH THE GFS IS
STILL MORE AGGRESSIVE WITH DEVELOPING AFTERNOON TSTORMS NEAR AND WEST
OF THE LARAMIE...BELIEVE THE DRY AIR AND SUBSIDENCE ALOFT WILL
GREATLY SUPPRESS COVERAGE OF THESE TSTORMS. KEPT POP BETWEEN 15 TO 25
PERCENT FOR THE LOWER ELEVATIONS AND UP TO 40 PERCENT FOR THE
MOUNTAINS. LOWERED POP BELOW 10 PERCENT EAST OF A LINE FROM
CHEYENNE TO ALLIANCE. HOT TEMPERATURES WILL CONTINUE AND SPREAD
WESTWARD INTO SOUTHEAST WYOMING ON WEDNESDAY WITH HIGHS IN THE LOW
TO MID 90S POSSIBLE. NEAR RECORD HIGHS AROUND 100 ARE EXPECTED
ACROSS WESTERN NEBRASKA...ALTHOUGH THE CURRENT RECORDS ARE ON THE
HIGH SIDE AT SIDNEY AND CHADRON...SO DO NOT EXPECT ANY RECORD
HIGHS WEDNESDAY. THURSDAY WILL LIKELY BE THE HOTTEST DAY OF THE
WEEK AS THE UPPER LEVEL HIGH SHIFTS WESTWARD INTO THE CENTRAL
ROCKIES. DUE TO EVEN MORE MIDLEVEL SUBSIDENCE...ANY SHOWERS AND
TSTORMS WILL BE BRIEF AND CONFINED TO THE MOUNTAINS. MODELS SHOW
LI/S ABOVE ZERO ACROSS MOST OF THE AREA...SO EXPECT MAINLY DRY
CONDITIONS ACROSS THE HIGH PLAINS WITH HIGHS BETWEEN 90 TO 100.
KEPT POP BELOW 10 PERCENT OUTSIDE OF THE MOUNTAINS AND HIGHEST
VALLEYS WEST OF THE LARAMIE RANGE.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 330 PM MDT TUE AUG 27 2013
LONG TERM LOOKS UNSEASONABLY WARM AS BOTH THE GFS AND ECMWF SHOW
THE MID-CONUS RIDGE MOVING WEST INTO COLORADO AND STICKING AROUND
FOR THE NEXT WEEK OR SO.
700MB TEMPERATURES REMAIN AT +16 TO +18C THROUGH SUNDAY MORNING.
LOOKING AT UPPER 90S AND NEAR 100 HIGHS FOR THE PANHANDLE AND
AREAS IN SOUTHEAST WYOMING EAST OF THE LARAMIE RANGE/MID TO UPPER
80S WEST. MAINLY DRY ACROSS THE CWFA...BUT CAN NOT RULE OUT
AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS FORMING OVER
THE MOUNTAINS AND THEN MOVING OFF ONTO THE PLAINS. DID
HOWEVER...REDUCE POPS FROM PREVIOUS FORECASTS.
LOOKS LIKE MONSOONAL MOISTURE RETURNS TUESDAY AS A PACIFIC STORM
SYSTEM MOVES INTO WASHINGTON STATE. THE LOW THEN MOVES NORTHEAST
INTO ALBERTA...BUT IT DOES HELP THE UPPER RIDGE AXIS TO MOVE OFF
TO THE EAST INTO THE WESTERN DAKOTAS. WE SHOULD SEE A SLIGHT COOL
DOWN IN TEMPERATURES AS THIS OCCURS WITH INCREASED CLOUD
COVER...POP CHANCES AND COOLING 700MB TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1051 AM MDT TUE AUG 27 2013
VFR CONDITIONS FOR OUR NEBRASKA PANHANDLE AIRPORTS AND RAWLINS
THROUGH THE NEXT 24 HOURS. LATEST HRRR FORECAST...WHICH HANDLED
CONVECTION YESTERDAY PRETTY WELL...HAS GREATEST CONCENTRATION OF
SHOWERS AND THUNDERSTORMS OVER ALBANY COUNTY AND KLAR. DOES BRING
SHOWERS AND THUNDERSTORMS INTO THE CHEYENNE AREA LATER THIS
AFTERNOON...AFTER ABOUT 23Z OR SO. SO TIMED CONVECTION BASED ON
THIS GUIDANCE. CONVECTION SHOULD COME TO AN END QUICKLY AFTER
SUNSET.
&&
.FIRE WEATHER...
ISSUED AT 147 PM MDT TUE AUG 27 2013
FIRE WEATHER CONCERNS WILL BE MINIMAL THROUGH THE WEEK WITH
DAYTIME HUMIDITIES GENERALLY REMAINING ABOVE 20 PERCENT...WITH
GREAT OVERNIGHT RECOVERIES. THE ONLY CONCERN WILL BE OVER THE NEXT
FEW DAYS WITH NEAR RECORD HIGH TEMPERATURES EXPECTED OVER THE HIGH
PLAINS. IF THE BOUNDARY LAYER MIXES A BIT HIGHER THAN MODEL
SOUNDINGS SUGGEST...LOCALLY LOWER HUMIDITIES AROUND 15 PERCENT ARE
POSSIBLE WITH HOT TEMPERATURES DUE TO THE DRIER AIR ALOFT. WINDS
WILL BE OCCASIONALLY GUSTY WEDNESDAY AFTERNOON...BUT DO NOT EXPECT
GUSTS TO APPROACH 30 MPH. NOT MUCH OF A PATTERN CHANGE
ANTICIPATED OVER THE NEXT 7 DAYS AS A STUBBORN UPPER LEVEL HIGH
WILL REMAIN NEARLY STATIONARY BETWEEN THE CENTRAL ROCKIES AND
CENTRAL GREAT PLAINS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...CLAYCOMB
FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
355 AM EDT THU AUG 29 2013
.SYNOPSIS...
LOW PRESSURE JUST OFF THE VIRGINIA COAST WILL MOVE FURTHER OUT TO SEA
TODAY AND TONIGHT. HIGH PRESSURE FROM THE GREAT LAKES REGION WILL
THEN BUILD TOWARD THE AREA AND MOVE OFF THE COAST LATE FRIDAY. A
COLD FRONT IS EXPECTED FROM THE WEST LATE MONDAY BEFORE SLOWLY
MOVING OFF THE COAST LATE TUESDAY NIGHT. HIGH PRESSURE WILL THEN
BUILD INTO THE AREA PROVIDING SEASONABLY COOLER AND LESS HUMID
WEATHER BEGINNING THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...ESTF UPDATE AT 1230 AM CONTINUED WITH THE 1115
PM TUESDAY UPDATE WITH A LITTLE FOG INTO NNJ WITH LESS
SKYCOVER...LIGHT WIND RADIATION COOLING CONDITION IN NJ.
ISOLATED SHOWERS NOW DEVELOPING AND ENTERING BERKS COUNTY TO THE NW
OF KRDG AT 305 AM.
TODAY...LOOKING LIKE A HEAVY RAIN EVENT FOR PTNS SE PA THRU THE
DELMARVA OR SNJ VCNTY KRDG-KPHL-KACY SWWD WITH 21Z/27 SREF PROBS FOR
1 INCH OF RAIN...PWAT BUILDING TO 2.1 INCHES OVER DELMARVA...SLOW -
10 KT - NW-W STEERING CURRENTS AND A SHORT WAVE LIFTING MOISTURE
OVER A SHALLOW CONVERGENCE ZONE NEAR SFC LOW PRES SOMEWHERE OVER E
MD DE. WHILE SVR TSTMS ARE UNLIKELY DUE TO WEAK SHEAR AND TT UNDER
48C...GULLY WASHERS ARE LIKELY WITH KI IN THE MID 30S THIS AFTN
THERE...SWI NEAR -2 AND A NEAR 90F AIRMASS IN THE WARM SECTOR. ML
CAPE WILL BE NEAR 1400J WHERE AND WHEN ITS NOT INITIALLY NOT RAINING
DURING MIDDAY. LIGHT WIND.
THE 00Z/28 RGEM/GGEM LOOK TOO FAR NORTH WITH THEIR FCST QPF
BULLSEYES.
THIS FCST IS A 50 50 BLEND OF THE GFS/NAM ELEMENTS WITH SOME RGEM IN
THE SKYCOVER PTN OF THE FCST. NO SREF INPUT INTO THE POP BUT THE
NEAR TERM PTN OF THIS FCST HAS A RELIANCE ON THE RAP MODEL GUIDANCE
AS SEEN IN THE CONSTANTLY MODEL UPDATED COSPA PRODUCT.
HPCQPF 06Z GRIDS WERE USED...WHICH FORCED THE BOX WX TOOL WORDING OF
HEAVY RAIN POSSIBLE FROM JUST SW OF KPHL S AND WEST TODAY.
FOR THUNDER...USED THE KI 36 (BLENDED 00Z/28 NAM/GFS KI) FOR
THUNDER. THAT KEEPS THUNDER LIMITED INLAND.
WE DID REVIEW THE 00Z/28 SPCWRF FOR TIMING CONVECTION AND ALSO THE
NSSL WRF QPF FCST (TTN-CMAY AXIS WHICH LOOKS TOO FAR NE BUT ISOLATED
3 INCH AMTS).
NO FLASH FLOOD WATCH. HOURLY FFG OVER 2.5 INCHES AND 6 HRLY IS
GENERALLY OVER 4.5 INCHES. MY CONCERN WITH RESPECT TO FFG...CHESTER
COUNTY PA AND NEW CASTLE DE. HOWEVER THAT DOESNT RULE OUT OTHER
COUNTIES. ITS WHERE ANY TSTMS REPEAT OR ARE QSTNRY THIS AFTN.
CONFIDENCE: AVERAGE
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL.
THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN
PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL
EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER
06Z.
CONFIDENCE: ABOVE AVERAGE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE H5 RIDGE IS FORECAST TO REMAIN CENTERED NEAR THE FOUR CORNERS
REGION THROUGH MOST OF THE EXTENDED PERIOD AS IT AMPLIFIES BY THE
MIDDLE OF NEXT WEEK. AT THE SAME TIME, THE H5 TROUGH DIGS FURTHER
SOUTH INTO THE EASTERN U.S., THUS PREVENTING ANY PROLONGED PERIOD OF
ABOVE NORMAL TEMPERATURES FOR THE CWA.
AT THE SURFACE, HIGH PRESSURE OVER THE APPALACHIANS EARLY FRIDAY
WILL SLIP OFF THE COAST BY FRIDAY NIGHT, ESTABLISHING A SOUTHERLY
FLOW OVER THE REGION INTO THE EARLY PART OF NEXT WEEK. WARMER THAN
NORMAL TEMPERATURES WILL RESULT FOR SATURDAY THROUGH MONDAY. IN
TERMS OF PRECIPITATION...A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON SATURDAY WILL GRADUALLY BECOME MORE LIKELY UNTIL
MONDAY EVENING. THEN A COLD FRONT IS EXPECTED TO SLOWLY MOVE THROUGH
THE REGION MONDAY NIGHT INTO TUESDAY NIGHT, USHERING IN SEASONABLY COOLER
TEMPERATURES FOR THE MID-WEEK PERIOD. RIGHT NOW THE TIMING OF THIS
FRONT, AND THE TIME OF YEAR, WOULD SUGGEST A LOW CHANCE OF SEVERE
WEATHER WITH THIS FRONTAL PASSAGE, BUT THE SITUATION WILL CONTINUE
TO BE MONITORED.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING PRIOR TO 12Z...VFR WITH SCT-BKN CLOUDS AOA 5000
FT DEVELOPING. PATCHY MVFR OR IFR FOG POSSIBLE NEW JERSEY WHERE BEST
RADIATIONAL COOLING. SHOWERS DEVELOPING VCNTY KRDG AROUND 0715Z.
LIGHT WIND. CONFIDENCE: AVERAGE
TODAY AFTER 12Z...VFR CIGS OVERSPREADING THE AREA. ANY MORNING
FOG WILL BURN OFF BY 14Z. LIGHT WIND. SHOWERS AND SCT TSTMS
EXPECTED MOST TAF SITES FOR 1-4 HOURS. MOST LIKELY AREA FOR TSTMS
IS VCNTY KRDG-KPHL-KILG-KMIV. THE 06Z TAFS HAVE 3SM MDT SHOWERS
WHERE MY CONFIDENCE IS GREATEST FOR CONVECTION BUT NO MENTION OF
TSTM ATTM DESPITE MY EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A
TSTM TODAY. CONFIDENCE ON DETAILS: AVERAGE.
TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS
DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE
FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE
ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY
EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS
LATE .. AFTER 06Z...IS ABOVE AVERAGE.
OUTLOOK...
THURSDAY...MAINLY VFR. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS
ON THURSDAY AFTERNOON AROUND KABE AND KRDG.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT
AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY
MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
NO HEADLINES THROUGH TONIGHT.
ATLC SEAS WILL CONTINUE TO RUN AROUND 2-3 FEET.
LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING
THE DAY THEN EVENTUALLY NE TONIGHT.
NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK
THURSDAY.
OUTLOOK...
WEAK LOW PRESSURE IS FORECAST TO PASS OFF THE VIRGINIA COAST ON
WEDNESDAY NIGHT. HIGH PRESSURE SHOULD FOLLOW FOR THURSDAY THROUGH
SATURDAY. A WARM FRONT MAY APPROACH FROM THE SOUTHWEST ON SUNDAY.
WIND SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE
SMALL CRAFT ADVISORY CRITERIA THROUGH THE PERIOD.
&&
.RIP CURRENTS...
TODAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20 KT
ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH A
HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR
THURSDAY.
FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 11 PM EDT THIS EVENING
FOR ANZ454-455.
&&
$$
SYNOPSIS...MIKETTA
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...MIKETTA
AVIATION...DRAG/MIKETTA
MARINE...DRAG/MIKETTA
RIP CURRENTS...DRAG
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
343 AM EDT THU AUG 29 2013
.SYNOPSIS...
LOW PRESSURE JUST OFF THE VIRGINIA COAST WILL MOVE FURTHER OUT TO SEA
TODAY AND TONIGHT. HIGH PRESSURE FROM THE GREAT LAKES REGION WILL
THEN BUILD TOWARD THE AREA AND MOVE OFF THE COAST LATE FRIDAY. A
COLD FRONT IS EXPECTED FROM THE WEST LATE MONDAY BEFORE SLOWLY
MOVING OFF THE COAST LATE TUESDAY NIGHT. HIGH PRESSURE WILL THEN
BUILD INTO THE AREA PROVIDING SEASONABLY COOLER AND LESS HUMID
WEATHER BEGINNING THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...ESTF UPDATE AT 1230 AM CONTINUED WITH THE 1115
PM TUESDAY UPDATE WITH A LITTLE FOG INTO NNJ WITH LESS
SKYCOVER...LIGHT WIND RADIATION COOLING CONDITION IN NJ.
ISOLATED SHOWERS NOW DEVELOPING AND ENTERING BERKS COUNTY TO THE NW
OF KRDG AT 305 AM.
TODAY...LOOKING LIKE A HEAVY RAIN EVENT FOR PTNS SE PA THRU THE
DELMARVA OR SNJ VCNTY KRDG-KPHL-KACY SWWD WITH 21Z/27 SREF PROBS FOR
1 INCH OF RAIN...PWAT BUILDING TO 2.1 INCHES OVER DELMARVA...SLOW -
10 KT - NW-W STEERING CURRENTS AND A SHORT WAVE LIFTING MOISTURE
OVER A SHALLOW CONVERGENCE ZONE NEAR SFC LOW PRES SOMEWHERE OVER E
MD DE. WHILE SVR TSTMS ARE UNLIKELY DUE TO WEAK SHEAR AND TT UNDER
48C...GULLY WASHERS ARE LIKELY WITH KI IN THE MID 30S THIS AFTN
THERE...SWI NEAR -2 AND A NEAR 90F AIRMASS IN THE WARM SECTOR. ML
CAPE WILL BE NEAR 1400J WHERE AND WHEN ITS NOT INITIALLY NOT RAINING
DURING MIDDAY. LIGHT WIND.
THE 00Z/28 RGEM/GGEM LOOK TOO FAR NORTH WITH THEIR FCST QPF
BULLSEYES.
THIS FCST IS A 50 50 BLEND OF THE GFS/NAM ELEMENTS WITH SOME RGEM IN
THE SKYCOVER PTN OF THE FCST. NO SREF INPUT INTO THE POP BUT THE
NEAR TERM PTN OF THIS FCST HAS A RELIANCE ON THE RAP MODEL GUIDANCE
AS SEEN IN THE CONSTANTLY MODEL UPDATED COSPA PRODUCT.
HPCQPF 06Z GRIDS WERE USED...WHICH FORCED THE BOX WX TOOL WORDING OF
HEAVY RAIN POSSIBLE FROM JUST SW OF KPHL S AND WEST TODAY.
FOR THUNDER...USED THE KI 36 (BLENDED 00Z/28 NAM/GFS KI) FOR
THUNDER. THAT KEEPS THUNDER LIMITED INLAND.
WE DID REVIEW THE 00Z/28 SPCWRF FOR TIMING CONVECTION AND ALSO THE
NSSL WRF QPF FCST (TTN-CMAY AXIS WHICH LOOKS TOO FAR NE BUT ISOLATED
3 INCH AMTS).
NO FLASH FLOOD WATCH. HOURLY FFG OVER 2.5 INCHES AND 6 HRLY IS
GENERALLY OVER 4.5 INCHES. MY CONCERN WITH RESPECT TO FFG...CHESTER
COUNTY PA AND NEW CASTLE DE. HOWEVER THAT DOESNT RULE OUT OTHER
COUNTIES. ITS WHERE ANY TSTMS REPEAT OR ARE QSTNRY THIS AFTN.
CONFIDENCE: AVERAGE
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL.
THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN
PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL
EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER
06Z.
CONFIDENCE: ABOVE AVERAGE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE H5 RIDGE IS FORECAST TO REMAIN CENTERED NEAR THE FOUR CORNERS
REGION THROUGH MOST OF THE EXTENDED PERIOD AS IT AMPLIFIES BY THE
MIDDLE OF NEXT WEEK. AT THE SAME TIME, THE H5 TROUGH DIGS FURTHER
SOUTH INTO THE EASTERN U.S., THUS PREVENTING ANY PROLONGED PERIOD OF
ABOVE NORMAL TEMPERATURES FOR THE CWA.
AT THE SURFACE, HIGH PRESSURE OVER THE APPALACHIANS EARLY FRIDAY
WILL SLIP OFF THE COAST BY FRIDAY NIGHT, ESTABLISHING A SOUTHERLY
FLOW OVER THE REGION INTO THE EARLY PART OF NEXT WEEK. WARMER THAN
NORMAL TEMPERATURES WILL RESULT FOR SATURDAY THROUGH MONDAY. IN
TERMS OF PRECIPITATION...A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON SATURDAY WILL GRADUALLY BECOME MORE LIKELY UNTIL
MONDAY EVENING. THEN A COLD FRONT IS EXPECTED TO SLOWLY MOVE THROUGH
THE REGION MONDAY NIGHT INTO TUESDAY NIGHT, USHERING IN SEASONABLY COOLER
TEMPERATURES FOR THE MID-WEEK PERIOD. RIGHT NOW THE TIMING OF THIS
FRONT, AND THE TIME OF YEAR, WOULD SUGGEST A LOW CHANCE OF SEVERE
WEATHER WITH THIS FRONTAL PASSAGE, BUT THE SITUATION WILL CONTINUE
TO BE MONITORED.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING PRIOR TO 12Z...VFR WITH SCT-BKN CLOUDS AOA 5000
FT DEVELOPING. PATCHY MVFR OR IFR FOG POSSIBLE NEW JERSEY WHERE BEST
RADIATIONAL COOLING. SHOWERS DEVELOPING VCNTY KRDG AROUND 0715Z.
LIGHT WIND. CONFIDENCE: AVERAGE
TODAY AFTER 12Z...VFR CIGS OVERSPREADING THE AREA. ANY MORNING
FOG WILL BURN OFF BY 14Z. LIGHT WIND. SHOWERS AND SCT TSTMS
EXPECTED MOST TAF SITES FOR 1-4 HOURS. MOST LIKELY AREA FOR TSTMS
IS VCNTY KRDG-KPHL-KILG-KMIV. THE 06Z TAFS HAVE 3SM MDT SHOWERS
WHERE MY CONFIDENCE IS GREATEST FOR CONVECTION BUT NO MENTION OF
TSTM ATTM DESPITE MY EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A
TSTM TODAY. CONFIDENCE ON DETAILS: AVERAGE.
TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS
DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE
FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE
ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY
EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS
LATE .. AFTER 06Z...IS ABOVE AVERAGE.
OUTLOOK...
THURSDAY...MAINLY VFR. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS
ON THURSDAY AFTERNOON AROUND KABE AND KRDG.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT
AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY
MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
NO HEADLINES THROUGH TONIGHT.
ATLC SEAS WILL CONTINUE TO RUN AROUND 2-3 FEET.
LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING
THE DAY THEN EVENTUALLY NE TONIGHT.
NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK
THURSDAY.
OUTLOOK...
WEAK LOW PRESSURE IS FORECAST TO PASS OFF THE VIRGINIA COAST ON
WEDNESDAY NIGHT. HIGH PRESSURE SHOULD FOLLOW FOR THURSDAY THROUGH
SATURDAY. A WARM FRONT MAY APPROACH FROM THE SOUTHWEST ON SUNDAY.
WIND SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE
SMALL CRAFT ADVISORY CRITERIA THROUGH THE PERIOD.
&&
.RIP CURRENTS...
TODAY...LOW RISK DOES NOT MEAN NO RISK BUT ITS BEEN A LOW RISK
SUMMER IN OUR FCST AREA SINCE THE ATLANTIC TROPICAL BASIN HAS BEEN
NOTABLY QUIET...DESPITE A FEW NAMED STORMS THAT JUST HAVENT SENT
MUCH SWELL UP OUR WAY.
THURSDAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20
KT ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH
A HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR THURSDAY.
FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 11 PM EDT THIS EVENING
FOR ANZ454-455.
&&
$$
SYNOPSIS...MIKETTA
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...MIKETTA
AVIATION...DRAG
MARINE...DRAG
RIP CURRENTS...DRAG
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
133 AM EDT THU AUG 29 2013
.AVIATION...
THE WEATHER SHOULD REMAIN DRY THROUGH THE MORNING HOURS OVER THE
TAF SITES ALONG WITH LIGHT AND VARIABLE WINDS. THE WINDS WILL THEN
BECOME EASTERLY AT 5 TO 10 KNOTS THIS AFTERNOON ALONG THE EAST
COAST TAF SITES...AND WESTERLY AT KAPF TAF SITE AFTER 14Z
TODAY. SCATTERED SHOWERS SHOULD ALSO DEVELOP AROUND THE TAF SITES
LATE THURSDAY MORNING INTO THIS AFTERNOON. SO HAVE PUT IN VCSH FOR
ALL OF THE TAF SITES FOR THIS AFTERNOON. THERE COULD ALSO BE A FEW
STORMS AROUND THURSDAY AFTERNOON...BUT THE COVERAGE WILL BE FEW
AND FAR. SO WILL KEEP THE THUNDER OUT OF THE TAF SITES AT THIS
TIME.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS OVER
ALL OF THE TAF SITES OF SOUTH FLORIDA...DUE TO THE UNKNOWN TIMING
OF THE SHOWERS AND THUNDERSTORMS FOR LATER TODAY.
&&
.AVIATION...54/BNB
.PREV DISCUSSION... /ISSUED 847 PM EDT WED AUG 28 2013/
UPDATE...
ONLY CHANGES TO PREVIOUS FORECAST WERE DONE IN THE SHORT TERM...TO
ACCOUNT FOR THE PERSISTENT ACTIVITY ACROSS THE LAKE OKEECHOBEE
AREA AND SURROUNDING COMMUNITIES. LATEST HRRR RUN KEEPS THIS AREA WET
OVERNIGHT...WITH A DECREASE IN COVERAGE AFTER MIDNIGHT. 00Z
SOUNDING SHOWING A SLIGHTLY DRIER AIRMASS AT MID-LEVELS COMPARED
TO YESTERDAYS AND THIS MORNINGS OBSERVATIONS. THIS IS DUE TO THE COMBINATION
OF THE LOW PRESSURE WEAKENING WHILE MOVING NORTHEAST...ALLOWING
FOR A SOUTHWEST FLOW AT MID LEVELS TO BRING DRIER AIR TO THE AREA.
THIS IS CONSISTENT WITH CURRENT MODEL GUIDANCE AND FORECAST TREND.
&&
PREV DISCUSSION... /ISSUED 804 PM EDT WED AUG 28 2013/
AVIATION...
COVERAGE OF SHRAS/TSRAS ASSOCIATED WITH A PERSISTENT H5 LOW HAS
SLOWLY DIMINISHED ACROSS THE AREA EARLY THIS EVENING AND IS NOW
RELEGATED TO THE INTERIOR AND LAKE OKEECHOBEE AREAS. ACTIVITY
SHOULD CONTINUE TO DECREASE IN COVERAGE THROUGH THE EVENING AND
IS NOT EXPECTED TO AFFECT THE TAF SITES. WINDS SHOULD BECOME LIGHT
AND VARIABLE OVERNIGHT BEFORE LIGHT EASTERLY FLOW RETURNS TOMORROW
FOR THE EAST COAST SITES. KAPF SHOULD SEE A GULF BREEZE DEVELOP
DURING THE EARLY AFTERNOON HOURS TOMORROW AND PENETRATE INLAND DUE
TO THE WEAKER EASTERLY FLOW.
&&
PREV DISCUSSION... /ISSUED 224 PM EDT WED AUG 28 2013/
SHORT TERM (TONIGHT-FRIDAY NIGHT)...
THE LATEST MODEL GUIDANCE REMAINS IN DECENT AGREEMENT THROUGH THE
SHORT-TERM PERIOD AND INDICATES THE MID/UPPER LOW CURRENTLY OVERHEAD
THAT HAS LED TO THE ADDITIONAL CLOUD/RAINFALL COVERAGE WILL CONTINUE
TO INFLUENCE THE LOCAL WEATHER THROUGH THE BULK OF THE PERIOD AS IT
GRADUALLY LIFTS NNE OVER THE STATE WITHIN THE WEAKNESS IN THE RIDGE.
MODEL SOUNDINGS ACROSS THE LOCAL AREA SHOW THE DEEP LAYER FLOW
GRADUALLY SHIFTING TOWARD THE WEST TONIGHT THROUGH FRIDAY WITH THE
PRECIPITABLE WATER REMAINING AROUND AND JUST UNDER THE 2" MARK.
DECENT MID-LEVEL LAPSE RATES ACROSS THE AREA THURSDAY COULD RESULT
IN A FEW STRONG STORMS DEVELOPING PROVIDED ANY BREAKS IN THE CLOUD
COVERAGE ALLOWING FOR DESTABILIZATION. THIS COMBINED WITH THE DEEP
LAYER FLOW SHIFTING TO THE SW SHOULD FAVOR MUCH OF THE
AFTERNOON/EVENING DEVELOPMENT OVER THE EASTERN HALF OF THE PENINSULA
AND TOWARD THE EAST COAST EACH DAY. THE MAIN IMPACTS OR CONCERNS
WOULD BE MINOR FLOODING AND GUSTY WINDS IF THIS VERIFIES.
HOWEVER...UNCERTAINTY REMAINS HIGH AS THE LATEST HI-RES MODEL
REFLECTIVITIES FROM THE WRF SHOW MAINLY ISOLATED COVERAGE THROUGH
THIS TIME.
LONG TERM (SATURDAY-WEDNESDAY)...
CONDITIONS ARE EXPECTED TO TREND BACK TOWARD NORMAL THROUGH THE
WEEKEND AS UPPER HEIGHTS BEGIN TO RISE AND THE AFOREMENTIONED
MID/UPPER LOW LIFTS NORTH OF OUR LOCAL AREA. ANOTHER WEAK FRONTAL
BOUNDARY ASSOCIATED WITH AN UPPER TROUGH DEEPENING OVER THE EAST
COAST EARLY NEXT WEEK IS PROGGED TO ENTER THE STATE FROM THE NORTH
TUESDAY THROUGH THE MID-WEEK PERIOD. THESE FEATURES MAY BEGIN TO
SUPPORT ADDITIONAL RAIN CHANCES ACROSS THE STATE BY THE END OF THE
PERIOD IF THE EXTENDED GUIDANCE REMAINS PERSISTENT WITH THIS
SOLUTION.
MARINE...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH
THURSDAY AS AN UPPER LOW CONTINUES TO INFLUENCE THE LOCAL WEATHER.
MARINERS CAN EXPECT PERIODS WITH REDUCED VISIBILITIES...GUSTY
WINDS AND LOCALLY CHOPPIER CONDITIONS IN AND AROUND THIS ACTIVITY.
HIGH PRESSURE WILL BUILD BACK OVERHEAD THROUGH THE WEEKEND WITH
LIGHT WINDS CONTINUING.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 77 91 / 40 20 20 20
FORT LAUDERDALE 79 91 79 90 / 30 20 30 20
MIAMI 78 91 78 93 / 30 20 30 20
NAPLES 75 90 75 91 / 20 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...59/RM
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CDT THU AUG 29 2013
.DISCUSSION...
324 AM CDT
THE FORECAST CHALLENGES INCLUDE FOG IN THE NEAR TERM...THEN
INCREASING TEMPS AND THUNDERSTORM CHANCES FRIDAY...FOLLOWED BY A
COOL DOWN AND RETURN TO MORE SEASONABLE CONDITIONS TOWARD END OF THE
HOLIDAY WEEKEND.
GOES IMAGERY THIS MORNING SHOWS EXPANDING AREA OF STRATUS ACROSS
MUCH OF THE FORECAST AREA WITH SURFACE OBS AND WEBCAMS SHOWING A
SMATTERING OF DENSE FOG HERE AND THERE. ALL INDICATIONS ARE THAT THE
STRATUS IS THIN AND SHOULD BURN OFF QUICKLY THIS MORNING EXPECT NEAR
THE LAKE FRONT WHERE MARINE STRATUS AND POSSIBLY EVEN SOME FOG COULD
HOLD ON INTO THE AFTERNOON. ANOTHER COMPARATIVELY COOL DAY NEAR THE
LAKE WITH 70S RANGING QUICKLY UPWARD TO 80S INLAND JUST A FEW MILES
WITH UPPER 80S TO NEAR 90 EXPECTED SOUTHERN AND WESTERN PORTIONS OF
THE CWA.
SURFACE BOUNDARY STALLED OUT FROM SOUTHERN MINNESOTA TO CENTRAL
ILLINOIS WILL DISSIPATE THIS AFTERNOON INTO TONIGHT AS BROAD
SOUTHERLY FLOW DEVELOPS WITH SFC LOW TRACKING EAST INTO THE UPPER
GREAT LAKES FRIDAY MORNING. TRAILING COLD FRONT ALONG WITH GLANCING
BLOW FROM THE ASSOCIATED SHORTWAVE PASSING TO OUR NORTHEAST COULD
RESULT IN CONVECTION DEVELOPING FRIDAY AFTERNOON OVER SOUTHERN WI OR
POSSIBLY FAR NORTHERN ILLINOIS. HOT AND HUMID CONDITIONS WILL RESULT
IN MODERATE TO STRONG INSTABILITY ACROSS THE AREA THOUGH CONFIDENCE
IS LOW IN THE MAGNITUDE OF THE DEEP LAYER SHEAR. DEPENDING ON THE
TIMING AND TRACK OF THE VORT AND ASSOCIATED STRONGER MID LEVEL FLOW
SHEAR COULD BE WEAK TO POSSIBLY ON THE HIGHER END OF MODERATE. GIVEN
THE UNCERTAINTIES ABOUT POSSIBLE CONVECTIVE INITIATION AND MAGNITUDE
OF SHEAR IF STORMS DO FORM...CONFIDENCE IN SEVERE THREAT ISN`T HIGH
BUT WORTH KEEPING AN EYE ON SINCE NORTHWEST FLOWS CAN BE FULL OF
SURPRISES. MODELS ALL AGREE IN A RESURGENCE OF THE MORE INTENSE HEAT
AND HUMIDITY WITH HIGHS IN THE LOW TO MID 90S AND HEAT INDICES
POTENTIALLY GETTING UP CLOSE TO OR PERHAPS A BIT OVER 100 FRIDAY
AFTERNOON.
WEAK COLD FRONT LOOKS TO PASS THROUGH THE AREA FRIDAY NIGHT
RESULTING IN A WIND SHIFT TO THE NORTH AND SLIGHTLY COOLER AIR
ARRIVING SATURDAY...EXCEPT NEAR THE LAKE WHERE THE COOL DOWN WILL BE
MORE PRONOUNCED WITH THE FLOW OFF THE LAKE.
MUCH STRONGER SHORTWAVE WILL CREST THE TOP OF THE SLOWLY
RETROGRADING CENTRAL CONUS RIDGE SATURDAY BEFORE DIGGING SOUTHEAST
INTO THE GREAT LAKES REGION SUNDAY. STRONGER COLD FRONT WITH A MORE
ROBUST PUSH OF COOLER AND LESS HUMID AIR WILL MOVE THROUGH LATER
SUNDAY. ITS QUESTIONABLE HOW MUCH MOISTURE/INSTABILITY WILL BE
AROUND FOR CONVECTION WITH THIS SECOND FRONT IN THE WAKE OF THE
FIRST FROPA. HAVE MAINTAINED JUST CHANCE POPS FOR NOW WITH SOME
GUIDANCE STILL SUGGESTING A DRY SECONDARY FROPA AND GIVEN THE TRENDS
THIS SUMMER...DRIER IS USUALLY THE WAY TO GO.
DRY NORTHWEST FLOW THEN FORECAST TO SET UP OVER THE AREA THROUGH
MUCH OF NEXT WEEK. INITIAL PUSH OF COOLER AIR MONDAY INTO TUESDAY
WILL BE REPLACED WITH QUICK WARM UP MIDWEEK FOLLOWED BY ANOTHER
NORTHWEST FLOW COLD FRONT AND PUSH OF COOLER AIR. ALL IN ALL LOOKS
LIKE PRETTY TYPICAL EARLY METEOROLOGICAL FALL TYPE WEATHER.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CHANCE THAT IFR CIGS COULD MOVE BACK IN EARLY THIS
MORNING...ESPECIALLY AT MDW.
* EAST WINDS ARND 10 KT BCMG SE THIS EVENING ARND 05 KT.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS SETTLING OVER THE REGION RESULTING IN LIGHT TO
CALM WINDS. AN AREA OF LIFR TO IFR CIGS IS STILL PUSHING WEST OFF
OF THE LAKE AND EXPECTING IT TO REACH RFD BY 07Z. CIGS UNDER THE
STRATUS WILL RANGE FROM 002 TO 006 FT BASED ON CURRENT OBS WITH
VSBY BEING EVEN MORE VARIABLE. GUIDANCE INDICATES VSBY WILL DROP
AT ALL OF THE TERMINALS ARND 8Z AND TOOK THE MORE FOG PRONE AREAS
SUCH AS GYY...DPA...AND RFD DOWN TO 1 TO 1 1/2 SM. WITH FLOW OFF
THE LAKE AND BEING A BIT WARMER...KEPT MDW AND ORD AT 2SM.
ONCE MIXING GETS GOING THIS MORNING...ARND 14Z...THINKING THE FOG
AND STRATUS WILL QUICKLY ERODE LEADING TO A VFR DAY. WINDS WILL
BE EAST ARND 10 KT AND SLOWLY VEER TO SE ARND 5KT IN THE EVENING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN IFR CIGS STAYING OUT OF ORD AND MDW THIS
MORNING.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. CHANCE TS AFTERNOON AND NIGHT...LOCAL IFR POSSIBLE
WITH TSRA.
SATURDAY AND SUNDAY...VFR. CHANCE TS DAYTIME...SLIGHT CHANCE
NIGHTTIME...LOCAL IFR POSSIBLE WITH TSRA.
MONDAY AND TUESDAY...VFR. WX NIL.
TRS
&&
.MARINE...
310 AM CDT
HIGH PRESSURE IS OVER THE GREAT LAKES WITH LIGHT WINDS EXPECTED
TODAY. OVER THE SOUTHERN HALF OF THE LAKE WINDS WILL TURN ONSHORE
RESULTING IN VARIABLE WINDS. LOW PRESSURE CURRENTLY OVER THE
DAKOTAS SHIFTS EAST AND WINDS BECOME SOUTH AHEAD OF IT TONIGHT. THE
LOW PASSES OVER THE LAKE FRIDAY WITH NORTH WINDS EXPECTED BEHIND THE
LOW FRIDAY NIGHT. A BRIEF RIDGE OF HIGH PRESSURE MOVES OVER THE
LAKE SATURDAY BEFORE A MUCH MORE SUBSTANTIAL LOW PASSES NORTH OF THE
LAKE SUNDAY. GUIDANCE STILL DIFFERS ON THE TRACK OF THE LOW BUT
WENT WITH THE MORE CONSISTENT ECMWF MODEL THAT CONTINUES TO INDICATE
THE LOW WILL PASS NORTH OF THE LAKE. WINDS TURN NORTH BEHIND THE
LOWS COLD FRONT SUNDAY NIGHT WITH WINDS AT LEAST 15 TO 25 KT
EXPECTED SUNDAY NIGHT AND MONDAY. WILL MONITOR WINDS AND WAVES OVER
INDIANA NEXT MONDAY BECAUSE A SMALL CRAFT ADVISORY AND RIP CURRENT
STATEMENT MAY BOTH BE NEEDED FOR THE INDIANA NEARSHORE WATERS
MONDAY AND MONDAY NIGHT. HIGH PRESSURE MOVES IN MONDAY NIGHT
ALLOWING WINDS TO DIMINISH IN SPEED.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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[top]
Area Forecast Discussion
National Weather Service Lincoln IL
353 AM CDT Thu Aug 29 2013
.DISCUSSION...
ISSUED 317 AM CDT Thu Aug 29 2013
Weak cold front dropping through the CWA this morning breaking up
the persistence of the sfc ridge for the Midwest. Upper level
ridge remains firmly in place though it is weakening somewhat with
a series of short waves rotating over the ridge and dampening the
more amplified flow until the end of the weekend...when the
northwesterly flow is restored. Series of waves essentially bring
pops through the holiday weekend until Monday. In the short term,
some fog this morning in the vicinity of the front as it moves
into Central Illinois. Models in fair agreement about the
continuing heat...until the cooler air moves in for Monday
afternoon.
SHORT TERM...Today and tomorrow...
Heat continues. With only small differences in some of the
temperatures...and a slightly lower dewpoint on the back side of
the frontal boundary...todays heat indices will still climb into
the 90s. Tomorrow will climb again into the low 100s as a wave
passes to the north across the Great Lakes. For this forecast
run...keeping the pops to Friday night instead of the earlier QPF
in both the NAM and GFS that moves in Friday afternoon. Concern
for the trend requiring moving the precip up into the afternoon
tomorrow... particularly with watching the cold front actually
spawn activity after quite a cap was in place yesterday afternoon.
LONG TERM...Saturday through Wednesday...
Heat continues through the weekend...with low pops for sct precip
likely making the heat maxes patchy with respect to timing...and
clearing behind convection. Potential for high heat index values
continues...but will be tempered in some locations by rainfall.
Sunday night showers should move through with a cold front that
brings significantly cooler air in and highs on Monday will only
reach into the lower 80s. Even cooler on Tuesday into the upper
70s. Behind the front for Sun night/Mon morning...the forecast
dries out again. ECMWF was a bit slower with the passage of the
boundary...but the 00z has come around to a solution more in line
with the GFS. Anticipate that even the slight chance pops in the
extended will fall out of the AllBlend should the trend continue.
HJS
&&
.AVIATION...
ISSUED 1155 PM CDT Wed Aug 28 2013
A STRATUS DECK OF CLOUDS BELOW 1K FT ALONG WITH SOME FOG WITH IFR
TO MVFR VSBYS OFF LAKE MI HAS BEEN DRIFTING STEADILY SSW TOWARD
RANTOUL AND DANVILLE. HRRR MODEL SEEMS TO BE HANDLING THIS STRATUS
CLOUD DECK THE BEST AND USED THIS MODEL FOR THE AVIATION FORECAST
OVERNIGHT INTO THU MORNING. HAVE IFR TO MVFR CONDITIONS MOVING
INTO CMI BETWEEN 06Z-07Z...BMI FROM 07Z-08Z AND PIA AND DEC 10Z-12Z.
CONFIDENCE OF THESE LOW CLOUDS OF 500-1K FT AND VSBYS AS LOW AS
1-3 MILES LOWERS AS YOU GO FURTHER SW ACROSS CENTRAL IL. HRRR
KEEPS LOW CLOUDS NE OF SPI THOUGH FOG COULD DEVELOP THERE TOO WITH
VSBYS 2-4 MILES DEVELOPING OVERNIGHT. FOG AND LOW CLOUDS TO
DISSIPATE/SCATTER OUT BETWEEN 14Z-15Z THU WITH VFR CONDITIONS
EXPECTED BY THU AFTERNOON. ENE WINDS STAY FAIRLY LIGHTER UNDER 10
KTS NEXT 24 HOURS AS FRONTAL BOUNDARY NEAR SPI PUSHES SLOWLY SW
AND WEAKENS DURING OVERNIGHT INTO THU.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1247 AM CDT THU AUG 29 2013
.DISCUSSION...
955 PM CDT
A CHALLENGING OVERNIGHT INTO EARLY MORNING FORECAST WEIGHING HOW
WIDESPREAD AND THICK FOG WILL BE. OVERALL HAVE NOT MADE TOO MANY
CHANGES TO GOING FORECAST...WITH AREAS OF FOG SOME LOCALLY DENSE
BEING THE PRIMARY WORDING USED.
THE COOL FRONT CONTINUES TO SLOWLY MOVE SOUTHWARD AND IS LOCATED
JUST SOUTH OF THE CWA THIS EVE. LINGERING DEW POINTS IN THE UPPER
60S TO LOW 70S REMAIN TO THE NORTH...ALONG WITH JUST A FAIRLY MOIST
COLUMN WITH THE 00Z DVN RAOB RECORDING A PWAT OF SLIGHTLY OVER TWO
INCHES. OCCASIONAL SCATTERED 2000-5000 FT CLOUDS HAVE BEEN SEEN
IN THIS MOIST POST FRONTAL AIR MASS. OF GREATER CONCERN IS AN AREA
OF STRATUS THAT IS THE REMNANTS OF A MUCH LARGER AREA OVER LAKE
MI TODAY. THIS AREA NOW ENCOMPASSES DOWNTOWN CHICAGO AND INTO
NORTHWEST INDIANA. PER WEB CAMS OF DOWNTOWN CHICAGO AND
OBSERVATIONS THIS HAS LOWERED TO 400-800 FT. COULD FORESEE THIS
SLOW SETTLING TREND TO CONTINUE WITH ONLY SUBTLE DRY AIR ADVECTION
IN THE LOW-LEVELS. AM MOST CONCERNED NEAR THE PERIPHERY OF THE
CURRENT STRATUS WHERE SATURATION IS LIKELY TO OCCUR EVEN LOWER IN
THE VERTICAL. WITH AREA OF STRATUS STILL ADVECTING...AND
SCATTERED OTHER CLOUDS...INCLUDING EVEN HIGH CLOUDS FROM SHORT
WAVE IN WESTERN WI...JUST DID NOT FEEL CONFIDENT ENOUGH TO ISSUE
AN ADVISORY. DO BELIEVE THERE WILL BE SOME DENSE FOG IN PLACES IN
THE MORNING...MAYBE EVEN WIDESPREAD IN A FEW COUNTIES. JUST COULD
NOT DEFINE AN AREA AT THIS TIME. ALSO CURRENT OBSERVATIONS FROM
LAW ENFORCEMENT IN A FEW COUNTIES AND FROM THE SHORE OF LAKE
MICHIGAN INDICATE THAT VISIBILITY IS MAINLY PRETTY GOOD WITH ONLY
SOME LIGHT HAZE/FOG.
HAVE ADJUSTED HOURLY FORECAST TEMPERATURES/DEW POINTS TO MATCH
GOING TRENDS. CLOUDS WILL DICTATE A GREAT DEAL ON HOW LOW OR NOT
SO LOW MINS WILL FALL OUT. AREAS THAT REMAIN UNDER STRATUS FOR
MUCH OF THE NIGHT...LIKE ALONG THE IL/IN STATE LINE...SHOULD FALL
OUT WARMER THAN INITIALLY THOUGHT. HAVE BUMPED UP MINS SOME THERE
TOWARD BIAS-CORRECTED MOS. OTHERWISE DID NOT HAVE CONFIDENCE
ENOUGH TO ADJUST ANY OTHER LOCATIONS.
MTF
//PREV DISCUSSION...
306 PM CDT
FORECAST CONCERNS INCLUDE FOG POTENTIAL TONIGHT...TEMPERATURES AND
SHOWER/T-STORM CHANCES LATE IN THE WEEK INTO THE WEEKEND.
SHORT TERM...TONIGHT THROUGH SATURDAY...
TONIGHT...THE WEAK FRONT DROPPING SOUTH THROUGH THE AREA TODAY WILL
STALL JUST OUTSIDE THE CWA TONIGHT INTO THURSDAY AND A WEAK SURFACE
RIDGE WILL SPREAD SOUTHEAST OVER THE WESTERN LAKES REGION. FORECAST
SOUNDINGS SHOW A MOIST LOW LEVEL AIR MASS BUT PLENTY OF DRY AIR
ALOFT...WHICH IS A GOOD SET-UP FOR FOG VERSUS STRATUS. WILL NEED TO
WATCH FOR REEMERGENCE OF LAKE FOG BUT IT APPEARS TONIGHT WILL BE
MORE OF A RADIATIONAL FOG SET-UP WHERE RURAL AND SUBURBAN AREAS SEE
THE GREATER IMPACTS...ESPECIALLY NORTH OF INTERSTATE 80. RAW MODEL
OUTPUT AND MOS GUIDANCE SUGGESTS DENSE FOG IS POSSIBLE...BUT WILL
HOLD OFF ON AN ADVISORY AND ALLOW THE EVENING SHIFT TO ASSESS.
TEMPERATURES WILL LIKELY FOLLOW DEW POINTS DOWN TO THE MID-UPPER 60S
FOR MOST OF THE AREA OUTSIDE CHICAGO...WITH A FEW LOW 60S POSSIBLE
WEST OF THE FOX VALLEY.
CONFIDENCE IN AT LEAST PATCHY FOG...MEDIUM-HIGH.
CONFIDENCE IN DENSE FOG...MEDIUM.
THURSDAY THROUGH SATURDAY...THURSDAY WILL BE ANOTHER VERY WARM AND
HUMID DAY AWAY FROM THE LAKEFRONT WITH H85 TEMPS AROUND +20 TO +21
AND H9 TEMPS IN THE LOW-MID +20S. A SHORTWAVE OVER THE NORTHERN
ROCKIES THIS AFTERNOON WILL ROUND THE LARGE CENTRAL RIDGE TO THE
NORTHERN PLAINS AND UPPER MIDWEST BY THE EVENING. THE NORTHERN TRACK
OF THIS WAVE SHOULD KEEP THE FORCING FOR SHRA/TSRA NORTHWEST OF US
DURING THE DAY THURSDAY AND PRIMARILY TO THE NORTH THURSDAY NIGHT.
LIMITED SLIGHT POPS TO ONLY THE WISCONSIN BORDER.
UNCERTAINTY INCREASES GREATLY ON FRIDAY INTO SATURDAY AS SOLUTIONS
BEGIN TO DIVERGE AMONGST THE MODEL GUIDANCE IN THEIR HANDLING OF THE
STRENGTH OF THE LEAD WAVE. THE 12Z NAM AND CANADIAN ARE MUCH
STRONGER...DEVELOP AND TRACKING A CONSOLIDATED FAIRLY VIGOROUS
SURFACE LOW ACROSS LAKE MICHIGAN...WITH THE TRAILING COLD FRONT
SWEEPING ACROSS THE AREA LATE FRIDAY AND BRINGING A DRY AND COOLER
DAY ON SATURDAY.
FOR NOW WILL SIDE CONSERVATIVELY WITH THE GFS AND ECMWF
ROUTE...WHICH DO HAVE A COLD FRONT APPROACHING...BUT ALSO KEEP A
WEAK SURFACE LOW JUST TO OUR WEST INTO SATURDAY THAT THEN LARGELY
WASHES OUT ALONG WITH THE FRONT. WILL KEEP LOW CHANCE POPS MAINLY
FRIDAY AFTERNOON NORTH OF I-80 THEN NOT MAKE MAJOR CHANGES WITH
CHANCE POPS INTO SATURDAY DUE TO THE UNCERTAINTY. AS ALLUDED TO
EARLIER...TEMPERATURES HAVE BUST POTENTIAL ON FRIDAY...BUT IT
APPEARS THAT GUIDANCE IS ALLOWING FOR A WINDOW WHERE THE VERY WARM
THERMAL PROFILES/850 MB 20-22C 925 MB MID-UPPER 20S C WILL BE
TAPPED INTO. THUS WILL CONTINUE WITH PREVIOUS FORECAST IDEA OF LOW
90S AND A FEW MID 90S IN THE FAR WEST AND SOUTHWEST CWA. ITS
POSSIBLE THAT WINDS COULD TURN SOUTHEAST FRIDAY
AFTERNOON...RESULTING IN MINOR COOLING ALONG THE IL LAKEFRONT.
MAXIMUM HEAT INDEX VALUES ARE EXPECTED TO APPROACH 100 DEGREES AND
A FEW LOCATIONS COULD TOP 100 DEGREES...BUT AM NOT ANTICIPATING
NEEDING ANY HEADLINES. WITH THIS FORECAST SIDING MORE TOWARD THE
GFS/ECMWF SOLUTION THROUGH SATURDAY...SATURDAY WILL BE ANOTHER HOT
DAY IN THE LOW TO PERHAPS MID 90S FOR MOST OF THE AREA. WEAK FLOW
ALOFT WILL ENABLE A LAKE BREEZE TO WORK INLAND AND COOL OFF
LAKESHORE AREAS.
CONFIDENCE IN SHOWER/T-STORM TRENDS...LOW.
CONFIDENCE IN TEMPERATURES...MEDIUM.
LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...
THE UPPER LEVEL PATTERN WILL REALIGN IN THIS PERIOD...WITH A SHARP
AMPLIFICATION OF THE EASTERN NOAM TROUGH AND BETTER AGREEMENT AMONGST
THE GUIDANCE IN A STRONG SURFACE LOW TRACKING NORTH OF THE GREAT
LAKES AND INTO QUEBEC MONDAY. TRAILING FROM THIS LOW WILL BE A
STRONG COLD FRONT THAT WILL SWEEP ACROSS THE AREA ON
SUNDAY...BRINGING AT LEAST A CHANCE FOR SCATTERED STORMS. IT WILL BE
ANOTHER WARM TO HOT DAY AHEAD OF THE FRONT...WITH HIGHS DICTATED BY
FRONTAL TIMING. LOW 90S FOR PARTS OF THE AREA SEEM REASONABLE
AGAIN...ESPECIALLY SOUTH OF I-80. ON LABOR DAY...THE GFS AND ECMWF
HAVE COME INTO LINE WITH SUB 10C AIR AT 850...WHICH WILL RESULT IN
MOST AREAS IN THE MID 70S NORTH OF I-80 AND UPPER 70S SOUTH OF I-80.
THE LAKEFRONT WILL BE EVEN COOLER AND STRONG NORTH WINDS WILL LIKELY
RESULT IN DANGEROUS SWIMMING CONDITIONS DUE TO LARGE WAVES AND
STRONG CURRENTS. AFTER A COOL START TO TUESDAY...THE EASTERN TROUGH
WILL DEPART AND WARMING THERMAL PROFILES WILL SUPPORT SIMILAR IF NOT
SLIGHTLY WARMER AFTERNOON TEMPERATURES. WEDNESDAY WILL RETURN TO
SEASONABLE TEMPERATURES BUT THEN A PEEK BEYOND THE EXTENDED SHOWS
THE POSSIBILITY OF ANOTHER COOL DOWN...POSSIBLY SHARPER THAN EARLIER
IN THE WEEK.
CONFIDENCE IN SHOWERS/T-STORMS SUNDAY...MEDIUM.
CONFIDENCE IN TEMPERATURES...MEDIUM.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LIFR/IFR CIGS AND IFR VSBY THIS MORNING.
* EAST WINDS ARND 10KT BECOMING SE ARND 5KT IN THE EVENING.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS SETTLING OVER THE REGION RESULTING IN LIGHT TO
CALM WINDS. AN AREA OF LIFR TO IFR CIGS IS STILL PUSHING WEST OFF
OF THE LAKE AND EXPECTING IT TO REACH RFD BY 07Z. CIGS UNDER THE
STRATUS WILL RANGE FROM 002 TO 006 FT BASED ON CURRENT OBS WITH
VSBY BEING EVEN MORE VARIABLE. GUIDANCE INDICATES VSBY WILL DROP
AT ALL OF THE TERMINALS ARND 8Z AND TOOK THE MORE FOG PRONE AREAS
SUCH AS GYY...DPA...AND RFD DOWN TO 1 TO 1 1/2 SM. WITH FLOW OFF
THE LAKE AND BEING A BIT WARMER...KEPT MDW AND ORD AT 2SM.
ONCE MIXING GETS GOING THIS MORNING...ARND 14Z...THINKING THE FOG
AND STRATUS WILL QUICKLY ERODE LEADING TO A VFR DAY. WINDS WILL
BE EAST ARND 10 KT AND SLOWLY VEER TO SE ARND 5KT IN THE EVENING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE ON TIMING OF
IMPROVEMENT.
* HIGH CONFIDENCE IN VSBY TRENDS...MEDIUM-LOW CONFIDENCE ON HOW
LOW VSBY WILL GO AND MEDIUM-HIGH CONFIDENCE IN TIMING OF
IMPROVEMENT TO VFR.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. CHANCE TS AFTERNOON AND NIGHT...LOCAL IFR POSSIBLE
WITH TSRA.
SATURDAY AND SUNDAY...VFR. CHANCE TS DAYTIME...SLIGHT CHANCE
NIGHTTIME...LOCAL IFR POSSIBLE WITH TSRA.
MONDAY AND TUESDAY...VFR. WX NIL.
TRS
&&
.MARINE...
156 PM CDT
MAIN MARINE FORECAST CONCERNS INCLUDE THE POTENTIAL FOR PERSISTENCE
OR REDEVELOPMENT OF PATCHY/LOCALLY DENSE FOG TONIGHT...A BRIEF
PERIOD OF MODEST SOUTH WINDS FRIDAY AND TIMING THE PASSAGE OF
ANOTHER WEAK COLD FRONT LATE FRIDAY/FRIDAY NIGHT. A STRONGER COLD
FRONT SHOULD PUSH ACROSS THE LAKE LATE IN THE WEEKEND...WITH A
PERIOD OF RELATIVELY STRONG NORTH WINDS LATE SUNDAY NIGHT INTO
MONDAY.
EARLY AFTERNOON SURFACE ANALYSIS DEPICTS LOW PRESSURE CENTERED OVER
WESTERN PENNSYLVANIA...TRAILING A COLD FRONT ACROSS IN/IL WHICH
CONTINUED TO SINK VERY SLOWLY TO THE SOUTH. A WEAK AREA OF HIGH
PRESSURE WAS OVER THE UPPER MISSISSIPPI VALLEY AND NORTHERN LAKES.
THIS HIGH WILL CONTINUE TO DRIFT TO THE SOUTHEAST ACROSS LAKE
MICHIGAN TONIGHT...DRIFTING ACROSS THE CENTRAL LAKES THURSDAY AND
THURSDAY NIGHT. THE COMBINATION OF COOLER BUT STILL MOIST AIR OVER
THE LAKE HAS LED TO AREAS OF FOG/LOW STRATUS CLOUDS WHICH MAY TEND
TO REDEVELOP TONIGHT. HOWEVER...MODEL FORECAST SOUNDINGS SUGGEST
THAT THE MOIST LAYER OVER THE OPEN WATERS MAY BE SIGNIFICANTLY
SHALLOWER TONIGHT THAN IT WAS THIS MORNING WHICH LEADS TO SOMEWHAT
LOW CONFIDENCE IN HOW EXTENSIVE FOG MAY BE ACROSS THE LAKE TONIGHT.
THE COLD FRONT STRETCHED ACROSS THE MIDWEST WILL BEGIN TO LIFT BACK
NORTH AS A WARM FRONT ACROSS THE UPPER MIDWEST LATER THURSDAY AND
THURSDAY NIGHT...WITH LIGHT SOUTHEAST FLOW DEVELOPING ACROSS THE
LAKE AS THE SURFACE RIDGE CONTINUES TO DRIFT OFF TO THE EAST. THE
FIRST OF TWO UPPER DISTURBANCES WILL TRAVERSE ONTARIO AND THE
NORTHERN LAKES FRIDAY/FRIDAY NIGHT...WHICH WILL TRAIL A WEAK COLD
FRONT ACROSS THE LAKE ONCE AGAIN. MODELS ARE NOT IN GREAT AGREEMENT
IN HANDLING OF THE SURFACE PRESSURE FIELD LATE FRIDAY SATURDAY WITH
RESPECT TO THE SURFACE TROUGH WITH THIS FRONT...THOUGH THE OVERALL
TREND SEEMS TO BE TOWARD WEAK GRADIENT/WIND FIELD. A STRONGER UPPER
DISTURBANCE AND ASSOCIATED LOW PRESSURE CENTER WILL TRACK ACROSS
ONTARIO SATURDAY NIGHT INTO SUNDAY...WHICH WILL DRAG A STRONGER
FRONT SOUTH ACROSS THE LAKE SUNDAY. NORTH WINDS SHOULD STRENGTHEN
BEHIND THIS FRONT SUNDAY NIGHT...AS THE LOW DEEPENS OVER EASTERN
ONTARIO AND QUEBEC...AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
UPPER MIDWEST. NORTH WINDS 20-25 KT APPEAR LIKELY LATE SUNDAY NIGHT
INTO MONDAY BEFORE THE GRADIENT EVENTUALLY WEAKENS AS THE RIDGE AXIS
APPROACHES MONDAY NIGHT.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1200 AM CDT Thu Aug 29 2013
.DISCUSSION...
ISSUED 855 PM CDT Wed Aug 28 2013
Will be updating the forecast around 9 pm to remove the mention of
isolated showers and thunderstorms over the ne CWA this evening. A
few showers and thunderstorms occurred along a frontal boundary near
I-74 since 22Z/5 pm and just two remain at 845 pm near the Knox, Fulton
and Peoria county border and near Heyworth near the McLean and DeWitt
county border. Isolated convection has been weakening past hour
and should be gone during next half hour.
Frontal boundary just sw of I-74 will continue pushing slowly sw
through rest of central IL rest of tonight and have wsw winds turn
ne behind the front and generally less than 10 mph. Patchy fog to
develop during overnight after 1 am in moist airmass across ne
half where temps cools quicker toward dewpoints. Muggy dewpoints
have pooled from 73-78F over central and ne areas near the frontal
boundary. Lows in the upper 60s and lower 70s look on track with
coolest readings over ne areas where front has already passed by
and a bit stronger ne winds to advect in cooler air more.
07
&&
.AVIATION...
ISSUED 1155 PM CDT Wed Aug 28 2013
A STRATUS DECK OF CLOUDS BELOW 1K FT ALONG WITH SOME FOG WITH IFR
TO MVFR VSBYS OFF LAKE MI HAS BEEN DRIFTING STEADILY SSW TOWARD
RANTOUL AND DANVILLE. HRRR MODEL SEEMS TO BE HANDLING THIS STRATUS
CLOUD DECK THE BEST AND USED THIS MODEL FOR THE AVIATION FORECAST
OVERNIGHT INTO THU MORNING. HAVE IFR TO MVFR CONDITIONS MOVING
INTO CMI BETWEEN 06Z-07Z...BMI FROM 07Z-08Z AND PIA AND DEC 10Z-12Z.
CONFIDENCE OF THESE LOW CLOUDS OF 500-1K FT AND VSBYS AS LOW AS
1-3 MILES LOWERS AS YOU GO FURTHER SW ACROSS CENTRAL IL. HRRR
KEEPS LOW CLOUDS NE OF SPI THOUGH FOG COULD DEVELOP THERE TOO WITH
VSBYS 2-4 MILES DEVELOPING OVERNIGHT. FOG AND LOW CLOUDS TO
DISSIPATE/SCATTER OUT BETWEEN 14Z-15Z THU WITH VFR CONDITIONS
EXPECTED BY THU AFTERNOON. ENE WINDS STAY FAIRLY LIGHTER UNDER 10
KTS NEXT 24 HOURS AS FRONTAL BOUNDARY NEAR SPI PUSHES SLOWLY SW
AND WEAKENS DURING OVERNIGHT INTO THU.
07
&&
.PREV DISCUSSION...
ISSUED 215 PM CDT Wed Aug 28 2013
Upper level ridge continues to hold firmly over the central U.S.
early this afternoon. Several impulses were noted on the water
vapor loop rotating around the northwest periphery of the heat
dome with one such feature seen over the Dakotas, responsible for
a complex of storms over central and eastern South Dakota. An
upper level wave was depicted over parts of western KS rotating
north-northeast.
The lastest surface map indicates a weak cold front located just
north of Moline ese towards Pontiac. Temperatures to the south of
the front were into the upper 80s to middle 90s, while to the
north of the front, early afternoon readings were in the middle
80s.
SHORT TERM...Tonight through Saturday
The main challenge this period will be convection chances along
the front this evening...and then rain chances late Friday into
Saturday as a weak upper level disturbance tracks southeast into
the region. Mixed layer capes in the 2500-3000 J/KG range right
along the boundary with some weak convergence noted over the
past hour across north central IL. However, current 700 mb temps
were +12 to +13C with forecast soundings continuing to indicate
a rather deep warm layer extending from 950-700 mb which would
tend to suppress any organized updrafts later this afternoon.
Short term models indicate a rather narrow window of opportunity
late this afternoon into early this evening where the cap weakens
slightly with a bit better low level moisture convergence along
the front. Will keep an eye on satellite and radar trends this
afternoon and make a last minute decision whether to include some
isolated convection along the front.
The frontal boundary will slip to the south and west of the area
for Thursday but as far as any important changes in temperature
or dew points, not seeing it in model data. A light easterly wind
may be able to keep temperatures down a few degrees, however, dew
points are still expected to be at least in the upper 60s. The
weak surface high across the Great Lakes will begin to edge off to
our east late tomorrow with return flow setting up to our west.
Models indicate another shortwave pushing across the Dakotas into
Minnesota late Thursday night will kick off some scattered storms
to our north, but based on the orientation of the 850 thermal axis
and low level jet, most if not all the activity will remain out to
our northwest. The better low level warm advection and moisture
transport will begin to shift further east and south on Friday with
convection occurring over the northern Great Lakes shifting sse into
the better instability axis Friday afternoon, and especially Friday
night. However, with the better forcing remaining to our north, POPs
will remain in the slight chance category Friday night with
mentionable POPs continuing on Saturday, especially over the east.
Temperatures will inch back into the mid 90s over the far west on
Friday as our flow becomes more southerly, and depending on the
amount of cloud cover and any precip on Saturday, we should see
similar afternoon highs, especially across the west.
LONG TERM...Sunday through Wednesday
The pattern is then forecast to amplify across the Great Lakes
region early next week as the heat dome shifts west into the
Rockies while a trof deepens in over the upper lakes. This should
allow much cooler and less humid air into the midwest starting
on Labor Day and continuing into most of next week. It looks as
if a secondary upper wave will dig southeast into the Great Lakes
region by Wednesday helping to carve out a rather deep trof over
the eastern U.S. by the end of the week. So even though we may
temporarily cool off early next week, it looks as it there will
be one more surge of heat ahead of the second shortwave on Wed
with 850 temps around +22C by Wednesday afternoon, with a
significant cool down seen on the latest ECMWF on Thu and beyond
with forecast 850 mb temps of +6 to +8. Will play it a bit more
conservative with the temperatures that far out as the ECMWF was
quite a bit more aggressive/cooler with the initial trof digging into
the Lakes for early next week than what we are seeing now. Right now
we are looking at afternoon highs warming at least into the middle
80s by Wednesday afternoon.
With the initial trof digging southeast into the northern Great Lakes
early next week, combined with a very warm and moist atmosphere ahead
of the approaching cold front late Sunday, you would think it would
be an ideal setup for rainfall across the area. But that hasn`t
been the case for most of our area this Summer. Despite the more
favorable dynamics approaching late Sunday, we are still seeing
some rather warm temperatures in the 850-700 mb layer for Sunday
before the combination of 500 mb height falls and cooling break
down the warm layer by Sunday evening. Will carry mentionable POPs
ahead of the front west of the IL river during the day Sunday,
and over most of the area Sunday night, before the cold front and
precip chances shift off to our east and south by Monday.
Smith
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
356 AM EDT THU AUG 29 2013
.SYNOPSIS...
HIGH PRESSURE NORTH OF THE STATE WILL WILL KEEP IT DRY TODAY
ACROSS FAR NORTHERN MAINE. SHOWERS ACROSS CENTRAL AND INTERIOR
DOWNEAST MAINE WILL DIMINISH LATER TODAY. A FRONTAL BOUNDARY WILL
ADVANCE TOWARDS THE REGION FROM THE WEST LATE FRIDAY INTO THE
WEEKEND WITH MORE SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
CHALLENGING FCST THROUGH TODAY AT LEAST W/RAINFALL PLACEMENT.
LATEST RADAR IMAGERY SHOWED A SWATH OF RAIN OCCURRING ACROSS THE
CENTRAL HIGHLANDS(MT. KATAHDIN AND MILLINOCKET) SE INTO
WASHINGTON COUNTY. LATEST MESO ANALYSIS SHOWED THIS RAINFALL
LINING UP WELL A STRONG THETA E GRADIENT IN THE LLVLS COUPLED TO
LLVL CONVERGENCE. 1000-700 LAYER SHOWED SOME DEFORMATION BANDING
TO ADD TO THIS PER THE LATEST RUC W/UPPER LOW MOVING ACROSS THE
CWA. RAIN SHIELD HAS BEEN EXPANDING SOME INTO NORTHERN PISCATAQUIS
AND SE AROOSTOOK COUNTY. THE 12/00Z RUNS OF THE ECMWF DEPICTED
THIS QUITE WELL AND DECIDED TO BLEND THE ECMWF AND RUC FOR THE
POPS AND PLACEMENT OF RAIN THIS MORNING SHOWING 70-90% PRECIP
CHANCES FOR THE AFOREMENTIONED AREAS. ADDITIONAL RAINFALL OF UP TO
.75 INCHES IS POSSIBLE W/SOME LOCATIONS RECEIVING CLOSE TO AN
INCH. A FLOOD ADVISORY WAS ISSUED FOR THE MILLINOCKET AND BAXTER
STATE PARK REGION TO COVER THIS POTENTIAL. THE MILLINOCKET REGION
HAS ALREADY RECEIVED UP TO 1.5 INCHES OF RAIN SINCE WEDNESDAY
AFTERNOON. FURTHER NORTH, DRIER AIR WAS WEDGING DOWN FROM SE
CANADA W/HIGH PRES NOSING IN. THEREFORE, THERE WILL BE SHARP
CUTOFF OF PRECIP BOTH NORTH AND WELL TOWARD THE BANGOR AND BAR HARBOR
REGIONS. TEMPERATURES WILL BE A TOUGH CALL TODAY DEPENDING ON
WHERE THE SUN WILL BREAK OUT AND THIS LOOKS TO MOST LIKELY ACROSS
THE DOWNEAST AND SWRN AREAS. OTHERWISE, NE FLOW WILL KEEP CLOUDS
AROUND MUCH OF THE DAY LIMITING HEATING AS SEEN FROM THE LATEST IR
SATL SHOWING CLOUDS FILLING BACK IN EVEN ACROSS THE CROWN OF MAINE.
THEREFORE, AFTERNOON MAXES WILL STRUGGLE TO GET THROUGH THE UPPER
60S TODAY ACROSS MUCH OF THE REGION W/THE EXCEPTION OF THE
INTERIOR DOWNEAST(BANGOR AREA) AS TEMPERATURES ARE EXPECTED TO
CLIMB INTO THE LOWER 70S. STILL BELOW NORMAL FOR LATE AUGUST.
THINGS ARE EXPECTED TO DRY OUT AS LOW PRES PULLS AWAY AND HIGH
PRES RIDGES IN FROM THE WEST. DECIDED TO STAY CLOSE TO THE
DAYCREW`S OVERNIGHT LOWS W/READINGS DROPPING INTO THE UPPER 40S
NORTH AND LOW TO MID 50S CENTRAL AND DOWNEAST AREAS. ADDED PATCHY
FOG FOR LATE TONIGHT W/THE CLEARING AND WET GROUND FROM THE
RAINFALL. CENTRAL AND INTERIOR DOWNEAST WILL BE MOST PRONE TO THE
FOG DEVELOPMENT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
LOW PRESSURE ACROSS THE GREAT LAKES FRIDAY WILL BE MOVING SLOWLY
EAST AND A WEAK FRONTAL BOUNDARY WILL ALSO BE MOVING EAST. CLOUDS
WILL ONCE AGAIN BE ON THE INCREASE WITH THE CHANCE OF AN ISOLATED
SHOWER ACROSS WESTERN AND NORTHERN AREAS. THE FRONTAL BOUNDARY IS
THEN EXPECTED TO SET UP SOMEWHERE ACROSS CENTRAL OR NORTHERN MAINE
FRI NIGHT INTO SAT INCREASING THE CHANCE OF SHOWERS...ESPECIALLY
DURING THE AFTERNOON SATURDAY. OTHERWISE...IT IS EXPECTED TO MUGGY
WITH PATCHY FOG FRI NIGHT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE WEATHER PATTERN CAN BE SUMMED UP AS HIGHLY UNSETTLED. AN UPPER
TROUGH NEAR LAKE WINNEPEG SATURDAY EVENING IS EXPECTED TO AMPLIFY AS
IT MOVES EAST AND RE-ESTABLISH AN EAST COAST TROUGH...A PATTERN SEEN
OFTEN THIS SUMMER. THIS PATTERN WILL PRODUCE A MOIST SOUTHWEST FLOW
ALOFT AHEAD OF THE UPPER TROUGH WITH A SERIES OF SHORTWAVES TO
TRAVERSE THE AREA SUN THROUGH TUE. MUCH OF THE TIME IS LIKELY TO BE
CLOUDY AND MUGGY WITH OCCASIONAL BOUTS OF SHOWERS. IT IS IMPOSSIBLE
AT THIS TIME FRAME TO TIME OUT INDIVIDUAL SHORTWAVES SO WILL HAVE TO
HAVE A BROAD BRUSH OF HIGH CHANCE POPS THOUGH MUCH OF THE PERIOD
WITH THE UNDERSTANDING THAT LIKELY OR EVEN CATEGORICAL POPS WILL
BE NEEDED FOR SOME FORECAST PERIODS DOWN THE ROAD. THE AIR MASS
WILL FEATURE DAYTIME HIGHS WILL BE CLOSE TO NORMAL WITH LOWS WELL
ABOVE NORMAL IN THE MUGGY AIR MASS. IT MAY NOT BE UNTIL SOMETIME
LATE NEXT WEEK THAT THE TROUGH AXIS IS ABLE TO FINALLY PUSH EAST
OF THE AREA WITH SOME DRIER AIR.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
NEAR TERM: IFR/MVFR THIS MORNING ACROSS ALL TERMINALS IMPROVING TO
VFR LATER TODAY INTO THE EVENING. THERE IS POTENTIAL FOR MVFR
CONDITIONS DUE TO SOME FOG DEVELOPMENT LATER TONIGHT.
SHORT TERM: MAINLY VFR FRI OUTSIDE OF ANY PATCHY EARLY MORNING FOG.
CONDITIONS ARE EXPECTED TO LOWER FRI NIGHT TO IFR/MVFR IN STRATUS
AND PATCHY FOG...WITH MVFR MUCH OF THE TIME SAT THROUGH MON WITH
OCCASIONAL IFR.
&&
.MARINE...
NEAR TERM: NO HEADLINES ATTM. SOME CONCERN ABOUT WINDS THIS
MORNING AS THE GRADIENT HAS TIGHTENED A BIT MORE THAN WHAT THE
PREVIOUS GUIDANCE WAS SHOWING. 44027 WAS SUSTAINED AT 20 KTS
W/GUSTS TO 25 KT. CLOSER INTO THE INTRA-COASTAL ZONE, WINDS AROUND
15KT. USING A BLEND OF THE NAM12 AND GFS40 WINDS, DECIDED TO ADD
GUSTS TO 25 KT FOR THE OUTER ZONES TO ACCOUNT FOR THE STRONGER
PRES GRADIENT THIS MORNING AS LOW PRES PULLS NNE ACROSS THE NW
ALTC. THIS WILL NEED TO BE MONITORED FOR A POSSIBLE SCA IF WINDS
STAY UP LONGER. SEAS ARE HOLDING AT 2-4 FT AND KEPT SEAS IN THIS
RANGE THROUGH TONIGHT.
SHORT TERM: THE WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SCA LEVELS
THROUGH THE WEEKEND. A LONGER SLY FETCH IS EXPECTED TO DEVELOP
EARLY NEXT WEEK AS AN AREA OF LOW PRESSURE TO THE WEST OF THE WATERS
MOVES NORTH OF THE REGION TUESDAY. THERE IS THE POTENTIAL THAT SEAS
MAY APPROACH SCA LEVELS MON-TUE.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT
SHORT TERM...CB
LONG TERM...CB
AVIATION...HEWITT/CB
MARINE...HEWITT/CB
AREA FORECAST DISCUSSION
NWS CARIBOU ME
102 AM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL PRESS SOUTH OF THE AREA THIS EVENING. HIGH
PRESSURE WILL BUILD DOWN FROM THE NORTH LATE TONIGHT INTO
THURSDAY. ANOTHER FRONT WILL APPROACH ON FRIDAY.&&
.NEAR TERM /THROUGH THURSDAY/...
100 AM UPDATE...
LATEST RADAR IMAGERY SHOWING A BAND OF SHOWERS MOVING WSW ACROSS
THE CENTRAL HIGHLANDS AND PORTIONS OF INTERIOR DOWNEAST. THE
LATEST RUC HAD A GOOD HANDLE ON THE PLACEMENT OF THE SHOWERS AND
EXPANDED THE 60-70% POPS FURTHER WSW ACROSS THE CENTRAL HIGHLANDS
INTO SWRN PISCATAQUIS AND PENOBSCOT COUNTIES. ENHANCED THE
WORDING FOR HEAVY RAINFALL IN THIS BAND AS RADAR ESTIMATES WERE
SHOWING UP TO .50-.75 INCHES PER HOUR. THE LATEST GEM HANDLED THE
SKY FCST WELL PER THE LATEST IR SATL WHICH SHOWED SOME CLEARING
ACROSS NORTHERN MAINE. THIS IN TURN HAS ALLOWED TEMPERATURES TO
DROP OFF INTO THE UPPER 50S. TWEAKED THE OVERNIGHT LOWS TO ACCOUNT
FOR THIS AS WELL.
PREVIOUS DISCUSSION...
FOR SOME SUNSHINE FOR NRN PTNS OF THE FA BY MIDDAY THU AND THE
REST OF THE FA BY MID AFTN AS INTRUSION OF SOMEWHAT DRIER AIR
MOVES INTO THE REGION.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE RIDGING DOWN FROM THE NORTHEAST WILL BRING A CLEAR
TO PARTLY CLOUDY NIGHT WITH LIGHT WINDS THURSDAY NIGHT. SOME
PATCHY FOG IS LIKELY IN THE RIVER VALLEYS AND ALONG THE COAST. A
WEAK SHORTWAVE OF LOW PRESSURE SLIDING EAST SOUTHEASTWARD BENEATH
A TROUGH IN EASTERN CANADA WILL APPROACH ON FRIDAY. CLOUDS WILL
INCREASE AHEAD OF THIS SHORTWAVE AND SOME ISOLATED SHOWERS ARE
POSSIBLE IN CENTRAL OR WESTERN AREAS LATE IN THE DAY. A STATIONARY
FRONT FORMING ACROSS NORTHERN AREAS FRIDAY NIGHT MAY PROVIDE THE
FOCUS FOR SOME SHOWERS LATE FRIDAY NIGHT INTO SATURDAY. OTHERWISE
SATURDAY WILL TURN OUT MOSTLY CLOUDY WITH A SOUTHERLY BREEZE
BRINGING INCREASING HUMIDITY AND A CHANCE FOR SHOWERS OVER CENTRAL
AND NORTHERN AREAS ESPECIALLY DURING THE AFTERNOON.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
FRONTAL BOUNDARY IS FORECAST TO BEGIN MOVING NORTH SATURDAY NIGHT
WITH FAIRLY GOOD GUIDANCE AGREEMENT. ALSO THERE WILL BE A UPPER
LEVEL SHORTWAVE MOVING EAST. THESE FACTORS WILL INCREASE CHANCES
OF SHOWERS FOR SUNDAY ACROSS THE REGION. THIS BOUNDARY WILL MOVE
NORTH IN ADVANCE OF A SURFACE LOW/COLD FRONT AND UPPER LEVEL
TROUGH MOVING EAST OUT OF ONTARIO. THERE ARE SOME MODEL
DISAGREEMENTS IN TERMS OF INTENSITY AND LOCATION OF SURFACE LOW.
EITHER SOLUTION WILL BRING A UNSETTLED PATTERN FOR MONDAY AND
TUESDAY. SOME WRAP AROUND SHOWERS WILL BE POSSIBLE ON WEDNESDAY AS
LOW CONTINUES TO TRACK NORTH AND EAST OF THE REGION. HIGHS AND
LOWS WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE
PERIOD.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
NEAR TERM: CURRENT VFR CONDITIONS ARE XPCTD TO LOWER TO MVFR AND
IFR BEGINNING LATE THIS AFTN WITH THE ARRIVAL OF STEADIER SHWRS
AND CONTG INTO THIS EVE...WITH CONDITIONS SLOWLY IMPROVING FROM
THE FAR N LATE TNGT TO DOWNEAST THU MORN...RESULTING IN VFR
CONDITIONS MSLY ALL TAF SITES THU AFTN.
SHORT TERM: NEAR TERM: VFR CONDITIONS THURSDAY NIGHT MAY LOWER TO IFR IN
VALLEY FOG AT SOME SITES LATE. VFR CONDITIONS ARE EXPECTED FRIDAY.
CONDITIONS MAY LOWER TO MVFR FRIDAY NIGHT AND REMAIN MVFR WITH
LOCAL IFR CONDITIONS IN LOW CLOUDS ON SATURDAY. MVFR/IFR WILL BE
POSSIBLE IN HEAVIER SHOWERS SUNDAY AND MONDAY.
&&
.MARINE...
NEAR TERM: NO HDLNS XPCTD THRU THU. PATCHY FOG IS XPCTD OVR THE
WATERS OVRNGT...BUT WITH WINDS BECOMING SLIGHTLY OFFSHORE BY THU
MORN...ANY FOG SHOULD LIFT AT OR SHORTLY AFT SUNRISE THU. KEPT
CLOSE TO WW3 WV HTS...LOWERED TO 1 TO 2 FT ALG THE IMMEDIATE
COASTLINE.
SHORT TERM: WINDS AND SEAS ARE EXPECTED TO BE BELOW SCA THURSDAY
NIGHT THROUGH SATURDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
125 AM EDT THU AUG 29 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM EDT WED AUG 28 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER
THE CNTRL CONUS RESULTING IN ACYC FLOW FROM THE NRN PLAINS THROUGH
THE UPPER MS VALLEY AND GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM
NEAR CYPL-CYHD INTO NW MN SUPPORTED SOME SCT SHRA/TSRA. A MORE
SIGNIFICANT UPSTREAM SHRTWV WAS MOVING FROM IDAHO INTO WRN MONTANA.
MID CLOUDS OVER MN INTO NW WI LEFTOVER FROM EARLIER CONVECTION AND A
WAA PATTERN UPSTREAM...WERE SPREADING INTO WRN UPPER MI. AT THE
SFC...A WEAK RIDGE FROM NRN ONTARIO INTO UPPER MI HAS BROUGHT MOSTLY
CLEAR SKIES AND LIGHT WINDS ACROSS UPPER MI AND PROMINENT LAKE
BREEZES. INLAND...MIXING IN THE SLIGHTLY DRIER AIRMASS PWAT AROUND
1.0 INCH (NEAR NORMAL) HAS DROPPED DEWPOINTS TO AROUND 60F.
WITH MAINLY CLEAR SKIES AND LIGHT WINDS...SOME FOG WILL DEVELOP
OVERNIGHT. HOWEVER...THERE HAS BEEN ENOUGH LOW LEVEL DRYING SO THAT
THE FOG IS NOT EXPECTED TO BECOME AS DENSE OR WIDESPREAD AS LAST
NIGHT. IN ADDITION...SOME MID CLOUDS MOVING INTO THE WEST MAY ALSO
LIMIT THE RADIATIONAL COOLING. OTHERWISE...MIN TEMPS SHOULD AGAIN
DROP TO AROUND 60 INLAND WITH LOWER TO MID 60S ALONG THE GREAT
LAKES.
AS THE NRN ROCKIES SHORTWAVE MOVES THROUGH SRN SASK AND MANITOBA TO
NRN MN WAA AHEAD OF THE SYSTEM WILL BRING INCREASING CLOUDS ACROSS
THE CWA. SOME SHRA/TSRA SUPPORTED BY 310K-315K ISENTROPIC ASCENT
NORTH OF A WARM FRONT INTO SRN MN MAY BRING SOME SHRA/TSRA FROM WRN
LAKE SUPERIOR AND NW WI INTO THE FAR WEST LATE. HOWEVER...ONLY LOW
END POPS WERE INCLUDED AS THE BULK OF ANY PCPN IS EXPECTED TO HOLD
OFF UNTIL AFT 00Z.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 431 PM EDT WED AUG 28 2013
ONE OF THE CONCERNS INHIBITING WIDESPREAD CONVECTION THURSDAY NIGHT
WILL BE THE FACT THAT THE SFC LOW/MAIN TROUGH WILL REMAIN TO OUR S.
SO WHILE THE SHORTWAVE CROSSES UPPER MI...STORMS MAY BE A BIT MORE
ELEVATED. THE LATEST NON-EURO RUNS DO INDICATE THE POTENTIAL FOR
MODERATE TO HEAVY RAIN...PRIMARILY ACROSS LAKE SUPERIOR...WITH 2-3IN
FALLING SOMEWHERE ACROSS THE CWA. EXACT TIMING AND PLACEMENT OF THE
HEAVIER RAIN WILL NEED TO BE PINNED DOWN A BIT LATER. THERE WAS
ENOUGH CERTAINTY TO KEEP LIKELY POPS GOING OVER THE FAR W LATE
THURSDAY EVENING...AND ACROSS MUCH OF THE W HALF OVERNIGHT...BEFORE
CONTINUING THE TRACK AROUND THE 500MB RIDGE AND SHIFTING TO OUR SE
FRIDAY MORNING. THE MOST UNSTABLE AIR WILL LIKELY BE ACROSS THE
INTERIOR W AND TO OUR SW...CLOSER TO THE SFC LOW.
A TEMPORARY RIDGE WILL EXPAND ACROSS THE UPPER GREAT LAKES FRIDAY
EVENING AS THE SFC LOW STRETCHING FROM N LAKE MI TO E IA EXITS
ACROSS LOWER MI. DIMINISHED THE CHANCE OF SHOWERS/TS FOR FRIDAY
NIGHT AND SATURDAY...AHEAD OF THE DEEPENING CANADIAN LOW. THE SFC
LOW IS STILL FIGURED TO BE OVER LAKE WINNIPEG AROUND 12Z
SATURDAY...AND SHIFT ACROSS S ONTARIO/LAKE SUPERIOR SUNDAY
MORNING-AFTERNOON. THE ECMWF IS REMAINS THE DEEPEST AT THE SFC AND
ALOFT WITH THIS FEATURE...BUT THE 12Z GFS IS CATCHING UP. WILL
CONTINUE TO LEAN THE FCST A BIT CLOSER TO THE ECMWF SOLUTION FOR
MUCH OF THIS PERIOD. QUICKER THAN ITS RUN FROM YESTERDAY...THE 12Z
ECMWF DEVELOPS THE 500MB LOW OVER ONTARIO SUNDAY MORNING /ABOUT
18HRS FASTER THAN THE GFS/. THIS WILL BE THE START OF OUR NEAR TO
BELOW NORMAL TEMPERATURES...AS ANOTHER LOW DIVES INTO EASTERN CANADA
ON WEDNESDAY. THE RESULT WILL BE A SIGNIFICANT TROUGH SUPPRESSING
THE STRONG HIGH TO OUR SW...AND 60S AND LOW 70S RETURNING TO THE
FCST FOR MONDAY...BEFORE MODERATING BACK TO NORMAL /70S/ BY
WEDNESDAY. STRONGER NW WINDS OF 10-20KTS ACROSS LAKE SUPERIOR AND
850MB TEMPS OF 4-6C SHOULD KEEP TEMPS IN THE 60S MONDAY...ALONG WITH
THE POTENTIAL FOR SHOWERS/DRIZZLE NEAR LAKE SUPERIOR. WAY OUT IN THE
FUTURE...THE ECMWF DOES HAVE 0 TO -2C TEMPS ACROSS LAKE SUPERIOR ON
THURSDAY. WILL WILL NEED TO WAIT AND SEE ON THAT ONE. EITHER
WAY...THE WARM AIR LOOKS TO BE DONE FOR A WHILE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 124 AM EDT THU AUG 29 2013
SOME MID AND HIGH CLOUDINESS STREAMING ACROSS UPPER MI HAS MADE FOG
FCST OVERNIGHT MORE CHALLENGING. INITIALLY...CLOUDS WILL WORK TO
DELAY FOG DEVELOPMENT...BUT IT STILL LOOKS LIKE CLOUDS SHOULD THIN
OUT SUFFICIENTLY FOR SOME RADIATIONAL FOG TO DEVELOP. WHILE KCMX
SHOULD ONLY FALL TO MVFR...IT MAY NOT TAKE LONG FOR IFR CONDITIONS
TO SET IN AT KIWD/KSAW ONCE CLOUDS THIN OUT. MAY SEE SOME BRIEF
PERIODS WITH VIS DOWN TO LIFR/VLIFR. IF ENOUGH CLOUDINESS HAPPENS TO
LINGER THRU THE NIGHT...FOG WILL NOT DEVELOP. FOG WILL BURN OFF A
COUPLE OF HRS AFTER SUNRISE WITH VFR CONDITIONS TO FOLLOW. THERE
MIGHT BE ISOLD/SCT SHRA/TSRA LATE THIS AFTN...BUT CONFIDENCE IN
DEVELOPMENT IS VERY LOW...SO NO MENTION WAS INCLUDED IN FCST. BETTER
POTENTIAL FOR SHRA/TSRA WILL DEVELOP TONIGHT...ESPECIALLY JUST
BEYOND THIS FCST PERIOD...AS A RATHER STRONG DISTURBANCE APPROACHES
THE UPPER LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 PM EDT WED AUG 28 2013
PATCHY FOG WILL PERSIST THROUGH THROUGH THURSDAY AS RELATIVELY HIGH
DEWPOINTS REMAIN THROUGH THE WEEK. DRIER AIR BEGINS MOVING IN FOR
THE WEEKEND... LIMITING FOG POTENTIAL FOR THE WEEKEND. LIGHT WINDS
WILL PREVAIL THROUGH MUCH OF THE FORECAST PERIOD AS THE PRESSURE
GRADIENT REMAINS LIGHT UNDER THE INFLUENCE OF RIDGING ALOFT. THE
PRESSURE GRADIENT WILL TIGHTEN SUNDAY WITH THE PASSAGE OF A LOW
PRESSURE SYSTEM TO THE NORTH OF LAKE SUPERIOR. BEHIND THE COLD
FRONT...NORTHWEST WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 25
KNOT RANGE. WAVES WILL MAY ALSO BUILD INTO THE 3 TO 7 FOOT RANGE
WITH COLDER AIR MOVING IN.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1131 PM MDT WED AUG 28 2013
.AVIATION...
06Z TAF CYCLE
LIGHT SHRA CONTINUES ACROSS THE SW MTNS AND LOWER RIO GRANDE
VALLEY. DOES NOT LOOK PROMISING FOR SHRA TO MAKE IT TO KABQ SO
HAVE REMOVED VCSH FOR NOW. OTHERWISE...LIGHT SHRA WILL CONTINUE
OVERNIGHT WITH MT TOPS OCCASIONALLY OBSCURED ACROSS THE SW MTNS.
PRECIP LOOKS TO FAVOR SIMILAR AREAS ON THURS. ISO-SCT -TSRA IS
EXPECTED ACROSS THE NRN MTS WHILE TS POTENTIAL WILL REMAIN
UNCERTAIN FOR AREAS SW OF A LINE FROM KGUP TO KSRR DUE TO REMNANT
CLOUD COVER AND INSTABILITY CONCERNS. IF TS CAN DEVELOP...MAIN
THREATS WILL BE HVY RAIN/LOW VSBY AS PRECIPITABLE WATER VALUES
REMAIN WELL ABOVE NORMAL FOR THE AREA.
34
&&
.PREV DISCUSSION...805 PM MDT WED AUG 28 2013...
WILL CANCEL FLASH FLOOD WATCH EARLY BASED ON LATEST RADAR RETURNS.
ADJUSTED POPS DOWN SOME OVER W AND CNTRL AREAS ACCORDINGLY. FFA
AND ZFP OUT SHORTLY. CHJ
.PREV DISCUSSION...255 PM MDT WED AUG 28 2013...
A DEEP SUBTROPICAL MOISTURE SURGE HAS ARRIVED OVER SOUTHERN NM AS A
WELL DEFINED INVERTED TROUGH SHIFTS SLOWLY NORTHWEST OF THE AREA.
CIRA BLENDED TOTAL PWAT VALUES ARE 150-175PCT OF NORMAL OVER THE
EL PASO AREA...AND THIS MOISTURE WILL ADVECT NORTH THRU TONIGHT ON
INCREASING 700-500MB SSE FLOW. ABUNDANT CLOUD COVER HAS LIMITED
CONVECTION ACROSS MUCH OF THE SOUTH THUS FAR HOWEVER A SLUG OF
NMRS SHRA/TSRA DEVELOPING AROUND I-10 AND IS SLIDING NORTH. LATEST
RUC AND HRRR SHOW THIS MASS OF PRECIP MOVING NORTH UP THE RGV AND
SOUTHERN HIGH TERRAIN INTO THIS EVENING BEFORE TAPERING OFF AFTER
MIDNIGHT. HAVE TIGHTENED UP POPS FURTHER WITH FOCUS OVER CATRON...
SOCORRO...AND LINCOLN COUNTIES.
CLOUD COVER ASSCD WITH THIS AREA OF PRECIP WILL LINGER INTO EARLY
THURSDAY AND LIKELY LIMIT CONVECTION AGAIN UNTIL LATE DAY WITHIN
ITS PERIPHERY. MODELS DO SHOW A SIMILAR FEATURE TMRW BUT FARTHER
NORTH WITH A MASS OF SHRA/TSRA SLIDING ACROSS THE SW HIGH TERRAIN
AND SOUTHERN PORTIONS OF THE NM CONT DVD THRU MID DAY. CONVECTION
SHOULD BE MORE WIDESPREAD FOR THE REMAINDER OF THE HIGH TERRAIN
AFT 3 OR 4 PM AS THETA-E RIDGE VALUES ARE HIGHER AND LIFTED INDICES
MORE UNSTABLE.
THE REAL JUICE AND FORCING MOVES INTO THE REGION FRIDAY THRU MONDAY
WITH PWAT VALUES AVERAGING AROUND 1.2 INCHES. FOCUS FOR CONVECTION
WILL BE OVER NORTHERN AND WESTERN NM FRIDAY...THEN OVER CENTRAL
AND NORTHERN NM FOR SATURDAY THROUGH MONDAY AS A BACK DOOR FRONTAL
BNDRY MOVES SW OVER THE AREA. LCL HEAVY RAIN THREAT WILL INCREASE
AND FLASH FLOOD WATCHES ARE POSSIBLE FOR AT LEAST BURN SCAR AREAS
THRU THE LABOR DAY HOLIDAY. FOLKS PLANNING OUTDOOR ACTIVITIES OVER
THE HOLIDAY WEEKEND SHOULD PREPARE FOR WET WEATHER. TEMPS IN THIS
PATTERN WILL BE CLOSER TO SEASONAL NORMALS. GUYER
.FIRE WEATHER...
BASED ON SATELLITE IMAGERY...ABUNDANT MOISTURE IS TRYING TO FLOW UP
FROM MEXICO. SOUTHERN PORTIONS OF THE AREA...ESPECIALLY SOCORRO
COUNTY WESTWARD WILL EXPERIENCE WETTING RAIN TODAY AND TONIGHT.
ISOLATED WETTING RAIN WILL BE FOUND FURTHER NORTH OVER THE NORTHWEST
AND NORTH CENTRAL MOUNTAINS. THE MID LEVEL DRY INTRUSION WHICH WAS
SQUARELY OVER THE FORECAST AREA YESTERDAY HAS SHIFTED
NORTH/NORTHEAST...THUS THE LOWEST HUMIDITY VALUES ARE FOUND THERE.
OVERALL...HUMIDITY VALUES HAVE TRENDED UP TODAY.
MOISTURE WILL CONTINUE TO MOVE NORTH AND WESTWARD ON THURSDAY. THIS
WILL SET THE STAGE FOR INCREASE WETTING RAIN COVERAGE CENTRAL
MOUNTAINS WESTWARD DURING THE AFTERNOON AND EVENING. A PRETTY DECENT
WETTING RAIN SIGNAL SHOWS UP ACROSS THE NORTHWEST AND WEST CENTRAL
HIGHLANDS. DRIER AND MORE STABLE AIR WILL BE FOUND OVER THE EASTERN
PLAINS. HUMIDITY VALUES FOR THE MOST PART WILL TREND UP EVEN MORE
ALTHOUGH LOWER SLIGHTLY ACROSS THE FAR EAST. HIGH TEMPERATURES WILL
BE ABOVE NORMAL NORTH AND EAST AS THE HIGH CENTER SHIFTS MORE OVER
PORTIONS OF THE SOUTHERN ROCKIES AND PLAINS INCLUDING OVER PARTS OF
NEW MEXICO. DUE TO THE PROXIMITY OF THE HIGH PRESSURE
ALOFT...VENTILATION RATES WILL LOWER ACROSS MOST OF THE AREA.
THE WEATHER MODELS DEPICT A BROAD HIGH PRESSURE AREA OVER THE DESERT
SOUTHWEST AND SOUTHERN ROCKIES FRIDAY INTO SATURDAY. SMALLER
ATMOSPHERIC WAVES WILL ROTATE AROUND THIS HIGH PRESSURE AREA AND
KICK OFF SCATTERED TO NUMEROUS WETTING THUNDERSTORMS. WESTERN AND
NORTHERN PORTIONS OF NM WILL MOST LIKELY EXPERIENCE THESE WAVES.
DRIER AND MORE STABLE AIR ALOFT WILL REMAINED CENTERED OVER EASTERN
NM. THE FLOW ALOFT WILL BE RATHER WEAK DURING THIS PERIOD SO SOME
POOR VENTILATION RATES SHOW UP IN AREAS. HIGH TEMPERATURES WILL
GENERALLY BE NEAR NORMAL WEST AND SEVERAL DEGREES ABOVE NORMAL EAST.
MINIMUM HUMIDITY VALUES WILL ALSO BE IN THE 20S EAST AND CANT RULE
OUT SOME UPPER TEENS. THUS CURING OF THE FINE OR GRASS FUELS WOULD MOST
LIKELY CONTINUE THERE.
BOTH THE GFS AND ECMWF MODELS SHOW AN UPTICK IN WETTING
THUNDERSTORMS OVER THE ENTIRE FORECAST AREA SUNDAY INTO EARLY NEXT
WEEK. THE UPPER HIGH WEAKENS SOME AND ALLOWS THE ATMOSPHERE TO
BECOME MORE UNSTABLE. ABUNDANT LOW LEVEL MOISTURE WOULD ALSO BEGIN
TO FILL IN ACROSS THE FORECAST AREA AND ALLOW FOR SCATTERED TO
NUMEROUS WETTING STORMS. THIS PERIOD COULD BECOME SOME SORT OF PSEUDO
MONSOON BURST EVENT. WILL CONTINUE TO MONITOR THE MODELS AND GET A
BETTER GAUGE FOR CONFIDENCE AS TIME GOES ON. CONDITIONS WOULD THEN
GRADUALLY IMPROVE SOME ACROSS THE EASTERN PLAINS. 50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1122 PM CDT WED AUG 28 2013
.UPDATE...
ISSUED AT 1120 PM CDT WED AUG 28 2013
NO MAJOR CHANGES PLANNED TO THIS UPDATE. A BAND OF CONVECTION
WILL MOVE INTO WESTERN/CENTRAL ND OVERNIGHT AHEAD OF A STRONGER
SHORTWAVE. ADDITIONAL SHOWERS/STORMS MAY DEVELOP OVER EASTERN ND
LATER TONIGHT WITH INCREASING MID LEVEL WAA AND INSTABILITY. THIS
IS ALL HANDLED WELL IN THE CURRENT GRIDS. THERE COULD BE SOME VERY
PATCHY FOG BEFORE CLOUDS INCREASE...BUT WITH NO EVIDENCE OF FOG
YET AND THE HRRR NOT INDICATING ANY...FOR NOW WILL LEAVE OUT...BUT
SOMETHING TO MONITOR. THERE COULD BE SEVERE STORMS LATER TONIGHT
AND A BETTER CHANCE ON THU...WITH AMPLE INSTABILITY/SHEAR. PWATS
ALSO RISE OVER 2 INCHES IN SOME AREAS...SO LOCALLY HEAVY RAIN WILL
ALSO BE A THREAT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 323 PM CDT WED AUG 28 2013
WEAK SURFACE BOUNDARY HAS DROPPED OUT OF MANITOBA AND EXTENDS FROM
FLAG ISLAND TO JUST SOUTH OF ROSEAU TO ST THOMAS TO CANDO. THIS
BOUNDARY IS PROGGED TO DROP JUST A BIT SOUTH AND WITH DEW PTS NR
70 ALONG BOUNDARY AND HEATING OF TEMPS INTO THE LOWER 90S ALONG
BOUNDARY ALL CAUSING A FEW STORMS TO FIRE. WILL NEED TO INCLUDE
ISOLD POP FOR THIS THRU SUNSET.
OTHERWISE MAIN ACTION LATE TONIGHT. WATER VAPOR SHOWS NEXT SHORT
WAVE MOVING INTO SOUTHWEST MONTANA AT 19Z. THIS SHORT WAVE WILL
MOVE EAST ON TOP OF THE 500 MB RIDGE AND INTO ERN ND TOWARD 12Z
AND THEN INTO MINNESOTA THURSDAY THROUGH 18Z. ALL MODELS INDICATE
A 30-35 KT LOW LEVEL JET ALONG 850 MB BOUNDARY WHICH WILL LIE IN
THE CENTRAL PART OF THE STATE LIKELY JUST NORTH OF I-94.
SOUTHEASTERLY UPSLOPE FLOW INTO EASTERN MONTANA AIDING IN STORM
DEVELOPMENT THERE AND EXPECT AS SHORT WAVE MOVES INTO CNTRL
MONTANA STORM TO GROW IN COVERAGE AND SEEMS AS IF AN MCS IS LIKELY
TO FORM AND MOVE EAST INTO WRN ND LATER THIS EVE AND THEN CNTRL ND
OVERNIGHT REACHING THE RED RIVER VALLEY LIKELY AFTER 08Z. TRIED TO
TIME POPS A BIT MORE TOWARD THAT IDEA...WITH LIKELY POPS 09Z-12Z
IN MUCH OF ERN ND. SEVERE WX BY THEN QUESTIONABLE....BUT WITH
PWATS OF 2.10 INCHES ALONG 850 MB BOUNDARY HEAVY RAIN SEEMS
REASONABLE. COULD BE LOCALIZED FLASH FLOODING ISSUES BUT WHERE AND
WHEN CANNOT SAY AND CONDITIONS PRIOR TO RAIN HAVE BEEN VERY VERY
DRY.
SYSTEM WILL MOVE EAST WITH PRECIP ENDING IN THE MORNING IN ERN ND
AND IN THE AFTN IN NW MN.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT WED AUG 28 2013
DRY THURSDAY NIGHT AND FRIDAY WITH HIGH PRESSURE MOVING. A TAD
COOLER BUT NOT MUCH.
FOR SATURDAY THROUGH WEDNESDAY...LONG WAVE PATTERN IS ZONAL AND
SPLIT ACROSS NORTH AMERICA AT THE BEGINNING OF THE PERIOD AND
AMPLIFIES BY THE END OF THE PERIOD. LONG WAVE UPPER RIDGE REMAINS
FROM THE DESERT SOUTHWEST INTO MT. THE ECMWF AND GFS WERE IN
AGREEMENT AT 84 HOURS. THE ECMWF IS A FASTER SOLUTION THAN THE GFS
BY THE END OF THE PERIOD. BOTH GFS AND ECMWF HAVE SHIFTED WEST IN
THE LAST MODEL RUN. WILL BLEND THE ECMWF AND GFS.
WILL KEEP YESTERDAYS PRECIP FOR SAT NIGHT. BUMPED UP POPS FOR SUN.
TOOK OUT PRECIP FOR TUE.
TEMPERATURES WERE LOWERED A DEGREE OR TWO FOR SUN AND MON AND RAISED
ONE OR TWO DEGREES FOR TUE AND WED COMPARED TO YESTERDAYS RUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1120 PM CDT WED AUG 28 2013
THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE FROM WEST TO EAST
BY LATE TONIGHT INTO THU. EXPECT MAINLY VFR CONDITIONS...ALTHOUGH
MVFR AND EVEN IFR CONDITIONS ARE POSSIBLE NEAR STRONGER STORMS
CONTAINING VERY HEAVY RAIN AND STRONGER WINDS. THE BEST CHANCE FOR
PROLONGED RAIN TOMORROW SHOULD OCCUR ACROSS THE NORTH.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...DK
SHORT TERM...RIDDLE
LONG TERM...HOPPES/RIDDLE
AVIATION...DK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
300 AM CDT THU AUG 29 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT THU AUG 29 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST...STRONG SUBTROPICAL
RIDGING OVER THE CENTRAL PLAINS AND TROUGHING ALONG THE EAST COAST
OF THE U.S.. ROUNDING THE SUBTROPICAL RIDGE WAS A CLUSTER OF
SHORTWAVES OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA.
SHOWERS AND THUNDERSTORMS HAVE BEEN ACCOMPANYING THESE SHORTWAVES...
WHICH ALSO ARE BEING AIDED BY MOISTURE TRANSPORT FROM SOUTHERLY
20-30 KT 850MB WINDS PER RADAR VWP DATA ACROSS THE WESTERN DAKOTAS.
EASTERN EXTENT OF THIS MOISTURE TRANSPORT HAS PRODUCED SOME STORMS
NEAR FARGO. FARTHER EAST OVER THE FORECAST AREA...CONDITIONS HAVE
REMAINED DRY THUS FAR DUE TO LITTLE IF ANY FORCING AS WELL AS STILL
SOME DRY AIR ABOVE THE SURFACE LINGERING AROUND AS SEEN IN THE 00Z
MPX SOUNDING. SURFACE MOISTURE REMAINS HIGH...ESPECIALLY OVER
NORTHERN IOWA AND SOUTHERN MN WHERE DEWPOINTS ARE IN THE LOW 70S.
THIS HIGHER MOISTURE IS POOLED ALONG A WARM FRONTAL BOUNDARY
BISECTING IOWA NORTHWEST TO SOUTHEAST. AIRMASS REMAINS WARM ACROSS
THE UPPER MIDWEST...WITH 925MB TEMPS AT 00Z RANGING FROM 22C AT
GRB...TO 25C AT MPX AND DVN...AND 27-29C AT ABR...BIS AND OAX.
..HAZARDS..
1. HEAT. HEAT INDICES ARE AGAIN EXPECTED TO CLIMB INTO THE 90 TO 100
RANGE...HIGHEST IN NORTHEAST IOWA...BUT STILL NOT HIGH ENOUGH TO
WARRANT A HEAT ADVISORY MENTION.
2. STORMS. BULK OF THE STORM ACTION IS EXPECTED NORTH OF THE
FORECAST AREA THROUGH TONIGHT. HOWEVER...THERE IS A SMALL CHANCE
SOME OF THE STORMS COULD ROLL THROUGH LOCATIONS NORTHEAST OF I-94
TONIGHT AND PRODUCE LARGE HAIL AND DAMAGING WINDS.
..SYNOPTIC OVERVIEW..
29.00Z MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A RETROGRESSION
WESTWARD OF THE SUBTROPICAL RIDGE INTO COLORADO BY 12Z FRIDAY.
MEANWHILE...THE CLUSTER OF SHORTWAVES PRESENTLY TOPPING THE GENERAL
RIDGING ARE PROGGED TO CONTINUE MARCHING EAST...REACHING LAKE
SUPERIOR AND UPPER MICHIGAN BY 12Z FRIDAY. AS THESE SHORTWAVES PRESS
EAST...THE WARM FRONTAL BOUNDARY IN IOWA GETS LIFTED NORTHEAST...
PERHAPS ALL THE WAY INTO UPPER MI BY 12Z FRIDAY. ADDITIONALLY...ALL
INDICATIONS ARE THAT A LOW PRESSURE AREA WILL ACCOMPANY THE
SHORTWAVES...WHICH IS ALREADY EVIDENT OVER FAR SOUTHWEST NORTH
DAKOTA.
..DETAILS..
29.00Z MODEL GUIDANCE HAS DEFINITELY TRENDED DRIER FOR THE FORECAST
AREA FOR BOTH TODAY AND TONIGHT...A TREND THAT STARTED WITH THE
28.12Z MODEL GUIDANCE AND PREVIOUS FORECAST. IN FACT...THE 29.00Z
REGIONAL CANADIAN IS COMPLETELY DRY. CERTAINLY GIVEN THE TRACK OF
THE SHORTWAVES AND SURFACE LOW...CONFIDENCE IS VERY HIGH THAT
LOCATIONS NORTH OF HERE FROM NORTHERN MN THROUGH NORTHWEST WI AND
UPPER MI WILL SEE SHOWERS AND STORMS. THE ONLY QUESTION MARK IS IF
THE WARM FRONT LIFTING THROUGH THE AREA CAN SPARK ANY CONVECTION...
EITHER DRIVEN BY 310-315K ISENTROPIC LIFT / 850MB MOISTURE
TRANSPORT...OR THROUGH SURFACE BASED CONVECTION. THERE IS A THIRD
SCENARIO PRESENTED BY THE 29.00Z NAM...WHERE SOME OF THE CONVECTION
COMING OUT OF NORTH DAKOTA THIS MORNING ROLLS DOWN ALONG THE
FRONT...IMPACTING LOCATIONS ALONG/WEST OF THE MS RIVER. HOWEVER...
HRRR TRENDS SUGGEST THIS WILL NOT HAPPEN...WHICH MAKES SENSE TOO AS
THE STRONGEST LOW LEVEL MOISTURE TRANSPORT REMAINS AIMED NORTHWEST
AND NORTH OF THE AREA. CHECKING OUT SURFACE BASED CONVECTION
POTENTIAL...MODIFYING A VARIETY OF SOUNDINGS FROM THE RAP AS WELL AS
THE 29.00Z GFS ALL SHOW A CAP HOLDING IN PLACE...LOCATED AROUND
775MB. THIS CAP ORIGINATES FROM WARM AIR BEING ADVECTED IN SOUTH OF
THE SHORTWAVE TRACK. IMPRESSIVE TO SEE THAT ALL OF TODAY THE 29.00Z
GFS DOES NOT PRODUCE ANY PRECIPITATION...WHICH THAT SIGNAL ALONE
LENDS MORE CONFIDENCE TO A DRY FORECAST. TO HELP BLEND WITH
NEIGHBORING OFFICES TO THE NORTH...HAVE MAINTAINED 20 PERCENT
CHANCES ACROSS FAR NORTHERN PORTIONS OF THE FORECAST AREA.
AS WE HEAD INTO TONIGHT...THE 29.00Z GFS/NAM/ECMWF INDICATE
POTENTIAL FOR SOME CONVECTION NORTHEAST OF I-94 AS THE LOW LEVEL JET
STRENGTHENS. FEEL IT IS PRUDENT TO HAVE A 20-40 PERCENT CHANCE IN THIS
AREA. OTHERWISE CAPPING AND DRY CONDITIONS SHOULD DOMINATE THE REST
OF THE FORECAST AREA.
MUCH OF THE WARM ADVECTION TODAY OCCURRING SOUTH OF THE TRACK OF THE
SHORTWAVES IS PROGGED TO OCCUR UP IN THAT 700-800MB LAYER. 925MB
TEMPERATURES REALLY DO NOT RESPOND IN OUR FORECAST AREA UNTIL AFTER
00Z. 925MB READINGS ARE PROGGED VERY SIMILAR TO YESTERDAY...
THEREFORE...ANTICIPATING SIMILAR HIGHS. WITH DEWPOINTS RUNNING IN
THE UPPER 60S TO MID 70S...WE SHOULD SEE YET AGAIN ANOTHER DAY OF
HEAT INDICES IN THE 90-100 RANGE...HIGHEST OVER NORTHEAST IA WHERE
HIGHEST TEMPERATURES AND DEWPOINTS ARE EXPECTED. ANOTHER WARM NIGHT
ON TAP TONIGHT AS WARMER 925MB SURGES IN AND DEWPOINTS REMAIN UP.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM CDT THU AUG 29 2013
..HAZARDS..
1. HEAT. HEAT INDICES HAVE COME DOWN SLIGHTLY ACROSS NORTHEAST IOWA
FOR FRIDAY...NOW IN THE 95-100 RANGE. SATURDAY HAS ALSO COME
DOWN...NOW MOSTLY AT OR BELOW 90. SO IT IS POSSIBLE NOW THAT WE CAN
GET THROUGH LABOR DAY WEEKEND WITHOUT ANY HEAT ADVISORIES...A BIG
CHANGE FROM WHAT THINGS LOOKED LIKE 4-7 DAYS AGO.
..SYNOPTIC OVERVIEW..
FOCUS FOR MUCH OF THE LONG TERM PERIOD IS THE IMPACT THE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST WILL HAVE ON THE FORECAST
AREA. THIS TROUGH IS PROGGED TO BEGIN EJECTING OUT ON FRIDAY...
CAUSING RIDGING TO BUILD OVER THE NORTHERN PLAINS...AND IN RESPONSE
TURNING THE UPPER FLOW MORE NORTHWESTERLY OVER THE FORECAST AREA.
THIS NORTHWEST FLOW WILL HELP DRIVE A COLD FRONT THROUGH THE AREA ON
FRIDAY. HEADING INTO THE WEEKEND...THE TROUGH IS EXPECTED TO MARCH
ACROSS SOUTHERN CANADA...WITH GOOD MODEL AGREEMENT FOR IT TO DIG
INTO THE WESTERN GREAT LAKES REGION ON SUNDAY. A WARM FRONTAL
PASSAGE IS LIKELY AHEAD OF THE TROUGH LATE SATURDAY...FOLLOWED BY A
FAIRLY STRONG COLD FRONTAL PASSAGE SUNDAY MORNING. ALL INDICATIONS
ARE THAT THIS TROUGH WILL EVENTUALLY ENCOMPASS MUCH OF THE EASTERN
THIRD OF THE U.S. BY TUESDAY...ALLOWING HIGH PRESSURE TO COME INTO
THE FORECAST AREA AT THE SURFACE. THE FORECAST BEYOND TUESDAY IS
MORE UNCERTAIN...PARTICULARLY DRIVEN BY THE ECMWF WHICH SHOWS A VERY
POTENT NORTHERN STREAM SHORTWAVE TROUGH DROPPING DOWN INTO THE
WESTERN GREAT LAKES REGION ON WEDNESDAY. THE 29.00Z GFS/CANADIAN
SHOW THIS SAME FEATURE TOO...BUT KEEP IT MORE PROGRESSIVE AND
IMPACTING SOUTHEAST CANADA INSTEAD. THE TWO SCENARIOS ARE
DRAMATICALLY DIFFERENT WHEN IT COMES TO BOTH PRECIPITATION AND
TEMPERATURE FORECASTS.
..DETAILS..
WITH A COLD FRONT COMING THROUGH ON FRIDAY...THERE ARE QUESTIONS ON
CAN IT PRODUCE ANY PRECIPITATION...AS WELL AS ITS TIMING FOR IMPACT
ON TEMPERATURES. MODELS HAVE DEFINITELY SPED UP ON THE COLD FRONTAL
TIMING...ESPECIALLY THE 29.00Z ECMWF/CANADIAN...HAVING IT NOW REACH
DVN BY 00Z SATURDAY. IF THIS TREND CONTINUES...WE MAY NOT HAVE ANY
CONVECTION ON FRIDAY. HOWEVER...THE 29.00Z GFS/REGIONAL CANADIAN/NAM
DEPICT A SLOWER TIMING...SO HAVE KEPT SOME 20-30 PERCENT CHANCES
GOING FOR NOW. THE SPEEDING UP OF THE FRONT ALSO HELPS TO PUSH THE
SURGE OF WARM AIR COMING IN HERE TONIGHT SOUTHEAST QUICKER. AS A
RESULT...HIGHS HAVE BEEN LOWERED SLIGHTLY...WHICH ALSO LOWERS HEAT
INDICES.
MAINLY DRY CONDITIONS LOOK TO PREVAIL FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BECOMES FIRMLY IN CONTROL. LOWERED TEMPERATURES A
BIT DURING THIS PERIOD AS THE AIR COMING IN IS A LITTLE COOLER THAN
PREVIOUSLY FORECAST.
THE WARM AIR SURGE AS WELL AS MOISTURE TRANSPORT AHEAD OF THE POTENT
SHORTWAVE CROSSING SOUTHERN CANADA COMES ACROSS THE AREA SATURDAY
NIGHT. 29.00Z GFS/ECMWF/NAM/CANADIAN ARE ALL IN GOOD AGREEMENT
SHOWING SOME SHOWERS AND THUNDERSTORMS IN THIS WARM ADVECTION SURGE
COMING INTO THE FORECAST AREA...ESPECIALLY AFTER MIDNIGHT. RAISED
CHANCES TO 40-50...HIGHEST OVER WESTERN PORTIONS OF THE FORECAST
AREA. SOME OF THESE CHANCES PERSIST INTO SUNDAY WITH THE COLD FRONT
COMING THROUGH. AS IT STANDS RIGHT NOW...THE BULK OF THE COLD
ADVECTION BEHIND THE FRONT APPEARS TO WAIT UNTIL AFTER SUNSET SUNDAY.
BEYOND SUNDAY...HIGH PRESSURE DOMINATES FOR THE MOST PART EXCEPT FOR
POSSIBLY A COLD FRONTAL PASSAGE ON WEDNESDAY PER 28.12Z/29.00Z
ECMWF. BOTH ECMWF MODELS SUGGEST THE FRONT WILL HAVE LITTLE MOISTURE
TO WORK WITH SO IT COMES THROUGH DRY. THEREFORE...DRY CONDITIONS ARE
FORECAST BEYOND SUNDAY. THE BIGGER THING WILL BE TEMPERATURES. 925MB
TEMPS PLUMMET FROM 22-25C ON SATURDAY...TO 18-22C ON SUNDAY...AND
14-17C ON MONDAY. GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
POSSIBLY WEDNESDAY AS WELL...DEPENDING ON IF THAT COLD FRONT COMES
THROUGH OR NOT. LAST NOTE WOULD BE POTENTIAL FOR VALLEY FOG TUESDAY
MORNING...BUT TOO EARLY TO PUT THAT IN THE FORECAST AT THIS TIME
GIVEN HOW SENSITIVE VALLEY FOG CAN BE TO OTHER VARIABLES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1138 PM CDT WED AUG 28 2013
BAND OF MID LEVEL CLOUDS IS MOVING OFF TO THE EAST OF THE TAF
SITES...BUT SOME SCATTERED CLOUDS STILL REMAIN BACK ACROSS
SOUTHERN MINNESOTA INTO SOUTH DAKOTA. BOTH THE 29.00Z NAM AND
29.02Z RAP SOUNDINGS SHOW THIS MOISTURE LEVEL REMAINING THROUGH
THE NIGHT WHICH SHOULD HELP TO KEEP SOME CLOUDS FLOATING OVER.
THIS WILL HINDER THE FOG DEVELOPMENT SOME AS WILL THE LIGHT
SOUTHEAST WINDS THAT WILL PERSIST THROUGH THE NIGHT AS THE WEAK
SURFACE HIGH HAS BECOME CENTERED OVER EASTERN WISCONSIN AND LAKE
MICHIGAN. STILL EXPECT TO SEE SOME FOG FORM...BUT WITH THE IN AND
OUT CLOUDS AND LIGHT WINDS...WILL HOLD THE VISIBILITY RESTRICTION
TO MVFR. THIS FOG SHOULD BURN OFF RAPIDLY THURSDAY MORNING WITH
SOME DIURNAL CUMULUS FORMING IN THE LATE MORNING AND THEN
DISSIPATING IN THE EVENING. AS A SHORT WAVE TROUGH PASSES BY TO
THE NORTH...THE MID LEVEL CAP WILL REMAIN IN PLACE AND KEEP ANY
CONVECTION WELL TO THE NORTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE MAIN FOCUS TONIGHT INTO TOMORROW IS WITH THE CHANCES OF
PRECIPITATION AND WHETHER ANY FOG WILL DEVELOP OVERNIGHT AGAIN.
THE UPPER LEVEL FLOW CONTINUES TO BE SHAPED BY BROAD RIDGING THAT
IS CENTERED OVER THE PLAINS AND EXTENDS FROM THE SOUTHEASTERN US
TO THE SOUTHWESTERN US. ANY PRECIPITATION HAS COME ALONG THE NORTHERN
PERIPHERY OF THIS RIDGE AS MID LEVEL SHORT WAVE TROUGHS TRACK
ALONG THE RIM. THERE CURRENTLY ARE A PAIR OF SHORT WAVE TROUGHS
THAT WILL NEED MONITORING INTO TOMORROW...ONE WEAK ONE IN THE
DAKOTAS/WESTERN MINNESOTA AND ANOTHER RUNNING INTO MONTANA. AT THE
SURFACE...A COLD FRONT HAS STALLED OUT ACROSS CENTRAL IOWA WITH
RIDGING ACROSS THE NORTHERN GREAT LAKES. DEW POINTS HAVE REALLY
POOLED ALONG THE NORTHERN SIDE OF THIS FRONT WITH MID/UPPER 70S
ANALYZED FROM CENTRAL ILLINOIS THROUGH EASTERN/NORTHERN IOWA.
EARLIER STRATUS HAS ALSO BECOME MORE MIXED AS THE DAY HAS GONE ON
TODAY...WHICH HAS LEAD TO SOME QUICK WARM UPS AS WELL.
GOING INTO TONIGHT...THE FIRST SHORTWAVE IN THE DAKOTAS/MINNESOTA
WILL PROPAGATE TO THE EAST AND WILL HELP TO LIFT THE FRONT BACK TO
THE NORTH AS A WARM FRONT ACROSS SOUTHERN MINNESOTA. THE 18.12Z
NAM/GFS AND 18.18Z RAP SHOWS THE POOL OF HIGHEST 0-3KM MUCAPE
LIFTING NORTH AS WELL IN MINNESOTA AND BECOMING ORIENTED MORE
NORTH TO SOUTH FROM CENTRAL MINNESOTA TO EASTERN IOWA OVERNIGHT.
THE BEST LOW LEVEL MOISTURE TRANSPORT APPEARS TO BE IN CENTRAL
MINNESOTA AS WELL WHERE THE STRONGER PUSH/CONVERGENCE IS FROM THE
SOUTH. HAVE KEPT SOME LOW CHANCES OF SHOWERS/STORMS OVERNIGHT IN
PORTIONS OF SOUTHEAST MINNESOTA/NORTHEAST IOWA TO ACCOUNT FOR
THIS...BUT CONFIDENCE IS NOT OVERLY HIGH THAT THE FORCING WILL BE
ENOUGH TO PRODUCE SOME CONVECTION.
THE HIGHER CHANCES FOR PRECIPITATION WILL COME ON THURSDAY AS THE
SECOND MID LEVEL SHORT WAVE TROUGH PROPAGATES EAST FROM MONTANA
THROUGH THE DAKOTAS ON TOWARD THE UPPER GREAT LAKES. IT APPEARS
THAT AN MCS WILL DEVELOP OVER THE DAKOTAS FROM THIS FEATURE AND
TRACK TO THE EAST INTO MINNESOTA TOMORROW MORNING. AS THE
SHORTWAVE ENTERS MINNESOTA/NORTHERN WISCONSIN LATE TOMORROW
MORNING/AFTERNOON...CONVECTION MAY DEVELOP ALONG THE WARM FRONT
WHICH WILL BE LIFTING TO THE NORTH AS A LOW MOVES INTO CENTRAL
MINNESOTA. WITH THE HIGH INSTABILITY ON THE ORDER OF 2000-4000
J/KG AND DECENT SHEAR...CAN NOT RULE OUT SOME SEVERE WEATHER
ACROSS NORTHERN WISCONSIN THE AFTERNOON HOURS WITH LARGE
HAIL/DAMAGING WINDS THE MAIN THREATS. NORTHERN WISCONSIN IS ALSO
THE LOCATION OF THE HIGHEST PRECIPITATION CHANCES AS THIS TROUGH
MOVES THROUGH GOING INTO THURSDAY NIGHT.
WITH LIGHT WINDS AND HIGH AMOUNTS OF LOW LEVEL MOISTURE STILL IN
THE REGION...CAN NOT RULE OUT SOME FOG TONIGHT...PARTICULARLY IN
WESTERN WISCONSIN WHICH WILL BE CLOSER TO THE HIGH AND FURTHER
FROM ANY CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE COMPLEX WILL MOVE THROUGH ON THURSDAY NIGHT WITH A COLD FRONT
DROPPING DOWN ACROSS THE REGION ON FRIDAY. THE 28.12Z NAM/GFS
FORECAST SOUNDINGS DIFFER ON THE AMOUNT OF CAPPING THAT WILL BE IN
PLACE AHEAD OF THIS FRONT WITH THE NAM SHOWING MORE OF IT AND THE
GFS LESS. THUS...THE NAM IS MAINLY DRY WITH THE FROPA WHILE THE
GFS PRODUCES SOME QPF. KEPT SOME PRECIPITATION CHANCES IN THERE
FOR NOW...MAINLY IN WESTERN WISCONSIN.
TEMPERATURES WARM UP AHEAD OF THIS FRONT WITH HIGHS GOING BACK
INTO THE 90S ACROSS MUCH OF NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN. WITH HEAT INDICES AROUND 100F IN THE AFTERNOON...MAY
HAVE TO DO A HEAT ADVISORY FOR THIS REGION.
BEYOND THIS...A BIG PATTERN CHANGE IS ON THE WAY FOR SUNDAY AS A
MID LEVEL TROUGH DIGS DOWN FROM CANADA AND BRINGS A MUCH COOLER
AIR MASS DOWN INTO THE REGION. 850MB TEMPERATURES...WHICH
GENERALLY HAVE BEEN IN THE +15C TO +25C RANGE THE PAST WEEK...WILL
DROP TO ABOUT +7C SUNDAY NIGHT AFTER THE COLD FRONT SWINGS
THROUGH. WHILE STORMS LOOK POSSIBLE WITH THE COLD FRONT COMING
THROUGH...THE TIME OF THE DAY DOES NOT LOOK FAVORABLE FOR SEEING
SEVERE WEATHER AS THE FRONT WILL LIKELY COME THROUGH IN THE
MORNING BEFORE ANY HIGH INSTABILITY CAN BUILD. HIGH PRESSURE THEN
SETTLES IN FOR THE EARLY PART OF NEXT WEEK WITH MUCH COOLER AND
SEASONABLE TEMPERATURES ON TAP.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1138 PM CDT WED AUG 28 2013
BAND OF MID LEVEL CLOUDS IS MOVING OFF TO THE EAST OF THE TAF
SITES...BUT SOME SCATTERED CLOUDS STILL REMAIN BACK ACROSS
SOUTHERN MINNESOTA INTO SOUTH DAKOTA. BOTH THE 29.00Z NAM AND
29.02Z RAP SOUNDINGS SHOW THIS MOISTURE LEVEL REMAINING THROUGH
THE NIGHT WHICH SHOULD HELP TO KEEP SOME CLOUDS FLOATING OVER.
THIS WILL HINDER THE FOG DEVELOPMENT SOME AS WILL THE LIGHT
SOUTHEAST WINDS THAT WILL PERSIST THROUGH THE NIGHT AS THE WEAK
SURFACE HIGH HAS BECOME CENTERED OVER EASTERN WISCONSIN AND LAKE
MICHIGAN. STILL EXPECT TO SEE SOME FOG FORM...BUT WITH THE IN AND
OUT CLOUDS AND LIGHT WINDS...WILL HOLD THE VISIBILITY RESTRICTION
TO MVFR. THIS FOG SHOULD BURN OFF RAPIDLY THURSDAY MORNING WITH
SOME DIURNAL CUMULUS FORMING IN THE LATE MORNING AND THEN
DISSIPATING IN THE EVENING. AS A SHORT WAVE TROUGH PASSES BY TO
THE NORTH...THE MID LEVEL CAP WILL REMAIN IN PLACE AND KEEP ANY
CONVECTION WELL TO THE NORTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...04
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1016 AM EDT Thu Aug 29 2013
.NEAR TERM [Through Tonight]...
Looking at our sounding from Tallahassee this morning, there is a
strong capping inversion just above 750mb. Even if the cap can be
broken, there is still a bit of CIN present above the inversion.
Our morning sounding indicates quite a bit of dry air with below
normal PWATs for this time of year, and it appears the dry air
will continue to be advected into our CWA for at least the next
day. Therefore I think we are going to be hard pressed to get any
showers or thunderstorms today. If they are going to occur, the
best chance is along a weak surface trough extending through
central Georgia. Hi-Res model guidance such as the HRRR and WRF
are indicating some shower and thunderstorm activity late this
afternoon around the surface trough. Therefore bumped up PoPs just
a bit for our far eastern and northern GA counties.
This afternoon expect mostly clear skies with high temperatures
reaching the middle 90s with heat indices near 100.
&&
.SHORT TERM [Friday Through Wednesday]...
With the ridge off to the west expected to weaken further and a
weak surface trough moving into the region by Friday, a return to
more wet conditions can be expected by the weekend. Model guidance
continues to be in good agreement about increasing rain chances,
especially across the eastern third of the forecast area by Friday
afternoon. While a washout isn`t expected, rain chances will be
higher than recent days with pops nearing 50 percent along I-75 in
Southern Georgia.
By Saturday, rain chances become more uniform as our region is
located in between the ridge to the west and an upper trough to
the east of the Florida Peninsula. Expect an earlier start to
convection on Saturday morning and lasting into the evening hours
with rain chances around 50 percent, though these could increase
in future forecasts.
Afternoon temperatures will trend lower through the period due to
increased afternoon cloud cover and convective activity.
&&
.LONG TERM [Wednesday Night through Wednesday]...
At the start of the extended period, the forecast area will be
situated in a weakness between a strong upper ridge over the
western states and a weaker ridge over the Bahamas. A weakening
upper low is forecast to be in place across northern Florida. This
pattern should keep PoPs relatively high into early next week with
temperatures near seasonal norms. By late Tuesday into Wednesday,
a deep trough is forecast to develop over the eastern CONUS,
pushing a cold front into the southeastern states. The GFS is
faster and stronger with the front, pushing it off the panhandle
coast by Tuesday afternoon and bringing much drier air into the
region. The ECMWF is slower and weaker with the front, stalling it
across south Georgia or north Florida on Wednesday. The GFS is
often overzealous with fronts this time of year, so prefer the
Euro timing and strength. With this in mind, will keep some PoPs
in for the entire extended.
&&
.AVIATION [Beginning 14Z Thursday]...
[Through 12Z Friday] VFR conditions will continue throughout the
entire period. There is a small chance of thunderstorms for eastern
most terminals this aftn but PoPs remain low enough that this was
left out of the TAF package. After 07z, expect MVFR VSBYS to develop
all sites and MVFR CIGS likely especially at VLD.
&&
.MARINE...
Winds across the marine area are expected to increase to around 15
knots late this evening and continue into Friday in response to an
approaching surface trough. This trough will dissipate on Saturday
leaving our region in light to occasionally moderate southwesterly
flow into next week. No headlines are anticipated.
&&
.FIRE WEATHER...
High pressure and a dry airmass will dominate local weather one
more day but relative humidities will remain above critical levels.
With an approaching cold front, the airmass will begin to moisten up
on Friday with unsettled weather through the weekend. Hazardous fire
weather conditions are not anticipated in the foreseeable future.
&&
.HYDROLOGY...
Flows remain in recession across all basins with the exception of
the Suwannee. Modest rises will continue through this week across
the Middle and Lower Suwannee as routed flows from the
Withlacoochee and Alapaha Rivers progress downstream. From Branford
on through Fowler`s Bluff, the Suwannee will continue moving
toward action stage through the weekend and could near minor flood
stage at Wilcox (US-19) by the middle of next week. For more
information, check out the rivers and lakes tab on our homepage.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 95 73 93 73 92 / 10 10 40 30 50
Panama City 92 76 92 77 89 / 0 10 30 20 40
Dothan 94 73 94 73 92 / 10 10 30 20 50
Albany 95 75 93 73 91 / 20 20 40 30 50
Valdosta 95 72 93 71 90 / 20 20 50 30 50
Cross City 93 72 92 71 89 / 10 10 50 30 50
Apalachicola 90 76 90 77 87 / 0 10 30 20 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Navarro/Harrigan
SHORT TERM...Godsey
LONG TERM...Camp
AVIATION...Block
MARINE...Godsey/Navarro
FIRE WEATHER...Block
HYDROLOGY...Godsey
AREA FORECAST DISCUSSION
NWS MIAMI FL
918 AM EDT THU AUG 29 2013
.UPDATE...
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. ASSOCIATED WITH THE UPPER LEVEL LOW MID LEVEL
TEMPS ACROSS THE AREA ARE COOL (AROUND -8C). WHILE H6-H5 LAPSE
RATES ARE DECENT THAT IS NOT THE CASE ABOVE H5 AND BETWEEN H9 AND
H7. PWAT VALUES ARE RUNNING AROUND 10-20% BELOW NORMAL AS DRIER
AIR MASS HAS WORKED ITS WAY INTO THE REGION ASSOCIATED WITH
AFOREMENTIONED UPPER LEVEL RIDGE TO THE NORTH WHICH IS AN
IMPRESSIVE 597 DM HIGH. EVEN SOME SAHARAN DUST HAS WORKED ITS WAY INTO
THE REGION. ALL OF THIS EXPELS A LESS ACTIVE DIURNAL CONVECTIVE
CYCLE IN TERMS OF COVERAGE BUT STILL A POTENTIAL FOR ISOLATED STRONG
STORMS AS DRY LAYER AT LOW LEVELS COULD INDUCE STRONGER DOWNDRAFTS.
SO MAIN CONCERNS FOR TODAY ARE GUSTY WINDS AND LIGHTNING WITH A
FEW OF THE STORMS. THIS IS CONSISTENT WITH HRRR AND LOCAL HIGH RES
ENS MODELS. SHORT TERM GRIDS HAVE BEEN UPDATED ACCORDINGLY.
&&
.PREV DISCUSSION... /ISSUED 710 AM EDT THU AUG 29 2013/
AVIATION...
THE WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH THE EARLY MORNING
HOURS THEN BECOMING EASTERLY AT 5 TO 10 MPH FOR LATE MORNING AND
AFTERNOON HOURS. THE ONLY EXCEPTION TO THIS IS KAPF TAF SITE WILL
SWING TO A WESTERLY DIRECTION AND INCREASE UP TO 5 TO 10 MPH AFTER
14Z. THE WINDS WILL THEN DECREASE TO LIGHT AND VARIABLE AFTER 23Z
TONIGHT.
THERE COULD BE SOME SHOWERS AROUND THE TAF SITES FROM 14Z UNTIL 23Z
TODAY WITH ANY A FEW THUNDERSTORMS. HOWEVER...THE BEST COVERAGE
SHOULD BE OVER THE INTERIOR AREAS. SO HAVE KEPT THE VCSH IN THE
FORECAST FOR ALL OF THE TAF SITES ACROSS SOUTH FLORIDA. THE CEILING
AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS...DUE TO THE UNKNOWN
TIMING OF THE SHOWERS AND THUNDERSTORMS.
PREV DISCUSSION... /ISSUED 445 AM EDT THU AUG 29 2013/
DISCUSSION...
A PESKY UPPER LEVEL LOW CONTINUES TO MEANDER OVER SOUTH FLORIDA
TODAY. LOOKING AT WATER VAPOR, THERE IS ONLY MODERATE MOISTURE IN
THE MID AND UPPER LEVELS. PWATS WILL STILL APPROACH 2 INCHES
HOWEVER. LOOKING AT VARIOUS CONVECTIVE PARAMETERS, THERE IS STILL
NOT MUCH TO MENTION. 700MB VORTICITY ADVECTION IS BEST OVER PALM
BEACH COUNTY THIS AFTERNOON, ALTHOUGH, THERE IS ENOUGH TO POSSIBLY
GENERATE SHOWERS ACROSS MUCH OF SOUTH FLORIDA, ESPECIALLY NORTH OF
I75. LAPSE RATES ARE STILL VERY QUESTIONABLE ACROSS THE ENTIRE
AREA, WITH GENERALLY LESS THAN 6.8 FROM 1000MB TO 700MB. MODELS
SOUNDING ARE SHOWING A LITTLE MORE CAPE, BUT ONLY BETWEEN 1300 AND
1600 JOULES. STORM MOTION WILL BE AROUND 15KTS. SO NOT THINKING
ANY HEAVY RAINS FOR A PROLONGED PERIOD TODAY, ALTHOUGH STILL CAN
NOT RULE OUT LOCALIZED URBAN FLOODING WHERE THUNDERSTORMS ARE ABLE
TO FORM, GENERALLY IN THE LAKE REGION. ALSO, LOOKS AS THOUGH THERE
WILL BE CONVERGENCE ALOFT OVER THE MAINLAND, WITH DIVERGENCE
STAYING OVER THE ATLANTIC WATERS OFF SHORE FROM JUPITER. OVERALL,
NOT IMPRESSED WITH CONVECTIVE PARAMETERS TODAY. THINK MAYBE EVEN LESS
THEN YESTERDAY FOR THE SOUTHERN AREAS AND PERHAPS ABOUT THE SAME
FOR THE LAKE REGION.
AS THE LOW DRIFTS TO THE NORTH, CONDITIONS ARE PROGGED TO IMPROVE
THROUGH THE WEEKEND. MODELS ARE INDICATING THE LOW MAY FALL APART
BY THE WEEKEND AND HIGH PRESSURE TRYING TO BUILD IN. PWATS WILL
BEGIN TO DROP, BEING LESS THAN 1.5 INCHES AT TIMES. FOR THE
WEEKEND, THERE IS ALMOST NO 500MB VORT ADVECTION, AND ONLY WEAK
700MB ADVECTION. SO ONLY A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS FOR THE HOLIDAY WEEKEND ALONG THE COAST, AND LOW
CHANCE FOR THE INTERIOR LOCATIONS.
FOR THE BEGINNING OF NEXT WEEK, MODELS ARE DIFFERING ON AN UPPER
LEVEL TROUGH MOVING INTO THE EASTERN UNITED STATES. THE GFS DIGS
THE TROUGH FURTHER SOUTH, AFFECTING THE SOUTH FLORIDA WEATHER. THE
ECMWF IS A LITTLE LESS AGGRESSIVE, KEEPING THE TROUGH WELL NORTH OF
FLORIDA. BUT, GIVEN A LIKELY RETURN TO A MORE NORMAL DIURNAL
PATTERN, HAVE GONE WITH CHANCE POPS FOR MONDAY ACROSS THE ENTIRE
CWA EACH AFTERNOON THROUGH THE END OF THE FORECAST PERIOD.
AVIATION...
THE WEATHER SHOULD REMAIN DRY THROUGH THE MORNING HOURS OVER THE
TAF SITES ALONG WITH LIGHT AND VARIABLE WINDS. THE WINDS WILL THEN
BECOME EASTERLY AT 5 TO 10 KNOTS THIS AFTERNOON ALONG THE EAST
COAST TAF SITES...AND WESTERLY AT KAPF TAF SITE AFTER 14Z
TODAY. SCATTERED SHOWERS SHOULD ALSO DEVELOP AROUND THE TAF SITES
LATE THURSDAY MORNING INTO THIS AFTERNOON. SO HAVE PUT IN VCSH FOR
ALL OF THE TAF SITES FOR THIS AFTERNOON. THERE COULD ALSO BE A FEW
STORMS AROUND THURSDAY AFTERNOON...BUT THE COVERAGE WILL BE FEW
AND FAR. SO WILL KEEP THE THUNDER OUT OF THE TAF SITES AT THIS
TIME.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS OVER
ALL OF THE TAF SITES OF SOUTH FLORIDA...DUE TO THE UNKNOWN TIMING
OF THE SHOWERS AND THUNDERSTORMS FOR LATER TODAY.
MARINE...
AN UPPER LEVEL LOW WILL KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS
IN THE FORECAST TODAY, ESPECIALLY IN THE WATERS OFF PALM BEACH
COUNTY. CONDITIONS WILL IMPROVE THROUGH THE WEEKEND AS THE LOW
WEAKENS. GIVEN THAT WINDS ARE FORECAST TO REMAIN LESS THAN 10 KTS
AND NOT REMAIN IN ANY GIVEN DIRECTION FOR ANY SIGNIFICANT LENGTH
OF TIME, WAVE HEIGHTS WILL ONLY BE 1 TO 2 FEET FOR THE ATLANTIC
WATERS AND CALM TO 1 FOOT FOR THE GULF THROUGH THE WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 89 75 90 77 / 30 30 20 10
FORT LAUDERDALE 88 79 90 79 / 20 20 20 10
MIAMI 90 77 91 78 / 20 20 20 10
NAPLES 88 74 89 75 / 30 20 20 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
638 AM CDT THU AUG 29 2013
.UPDATE...
ISSUED AT 628 AM CDT THU AUG 29 2013
SURFACE OBSERVATIONS INDICATED LOCALLY DENSE FOG HAS FORMED JUST
ALONG THE BOUNDARY IN SE IA. FOG AND LOW STRATUS IS ALSO SHOWING UP
ALONG WHAT NOW LOOKS TO BE A REINFORCING BACKDOOR COOL FRONT THAT
CONTINUES TO ADVANCE WESTWARD ACROSS IL...REACHING FROM ABOUT
STOCKTON TO KEWANEE. HAVE UPDATED THE FORECAST TO HIT FOG WORDING
A LITTLE HEAVIER AND FOR MORE CLOUD COVER EARLY THIS MORNING. MOST
RECENT RAP MODEL 925 MB RH FIELDS INDICATE THE ADVANCING STRATUS
AND SEPARATE AREA OF STRATUS DEVELOPING OVER EAST CENTRAL IA MAY
MERGE INTO A DECK IN THE LOW LEVEL CONVERGENCE AXIS THAT COULD
HOLD FOR MUCH OF THE MORNING. WILL CONTINUE TO WATCH THESE TRENDS
CLOSELY AS ANY DELAYED CLEARING COULD IMPACT TEMPERATURES.
&&
.SYNOPSIS...
ISSUED AT 343 AM CDT THU AUG 29 2013
AT 07Z THE SURFACE BOUNDARY WAS NEARLY STATIONARY FROM N CENTRAL
IA...SOUTHEAST TO SOUTH CENTRAL IL...JUST SOUTH OF A LINE FROM OTM
TO SOUTHEAST IA TO MQB IN W CENTRAL IL. LIGHT EASTERLY WINDS AND
LOW LEVEL MOISTURE POOLING NORTHEAST OF THIS BOUNDARY WAS KEEPING
BOTH TEMPERATURES AND DEWPOINTS IN THE 70S OVER ALL BUT THE FAR
SOUTHWEST AND NORTHEASTERN PORTIONS OF THE FORECAST AREA. THIS
MOISTURE CONVERGENCE WAS RESULTING IN AREAS OF DEVELOPING LOW
CLOUDS AND FOG. SO FAR THIS HAS BEEN CONFINED TO CLOSEST TO THE
BOUNDARY IN SE IA AND W CENTRAL IL. SATELLITE FOG CHANNEL IMAGERY
SHOWED AN AREA OF LOW CLOUDS EXPANDING EAST OUT OF NE IL...IN THE
LIGHT EASTERLY FLOW AROUND HIGH PRESSURE OVER WI AND LOWER MI. 00Z
UPPER AIR ANALYSIS SHOWED THE UPPER RIDGE HOLDING STRONG FROM AR
AND MO N-NE INTO THE NORTHERN PLAINS. THE HEAT DOME REMAINED IN
PLACE OVER THE PLAINS AND ROCKIES WITH A THERMAL RIDGE OF 850 MB
TEMPERATURES IN THE LOWER 20S REACHING FROM NEB AND SD E-SE ACROSS
IA INTO THE OHIO VALLEY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT THU AUG 29 2013
CHALLENGES INCLUDE FOG TRENDS EARLY THIS MORNING...THEN THE
MAGNITUDE OF HEAT AND HUMIDITY TODAY AND TONIGHT AS THE ON-GOING
LATE AUGUST HEAT WAVE CONTINUES.
EARLY THIS MORNING...STRATUS DECK OVER NE IL WILL LIKELY CONTINUE
WESTWARD...BUT AT THE CURRENT RATE...DO NOT EXPECT IT TO REACH THE
MS RIVER UNTIL AFTER SUNRISE...AND CONFIDENCE NOT HIGH THAT IT WILL
HOLD TOGETHER OR CONTINUE AT THE SAME PACE. HAVE ALREADY UPDATED TO
ADD AREAS OF EARLY MORNING FOG FOR MUCH OF THE FORECAST AREA. BASED
ON TRENDS THE PAST FEW DAYS WITH THIS BOUNDARY...WILL EXPECT ANY FOG
TO BURN OFF BY MID MORNING.
THE STATIONARY FRONT IS STILL PROGGED TO SLOWLY DISSIPATE AS HIGH
PRESSURE BUILDS SOUTHEAST INTO THE GREAT LAKES AND WINDS BECOME
LIGHT SE TO SOUTH. SOUTHWEST OF THIS CONVERGENCE ZONE...IT WILL BE
ANOTHER DAY OF DEEP MIXING AND NEAR RECORD HEAT WITH THE AIRMASS
SUPPORTING HIGHS WELL INTO THE MID AND POSSIBLY UPPER 90S AND HEAT
INDEX READINGS BACK ABOVE 100. ALONG AND JUST NORTHEAST OF THE
BOUNDARY...DEWPOINTS LINGERING IN THE 70S WILL RESULT IN HEAT
INDEX READINGS ABOVE 100 AS WELL...DESPITE SLIGHTLY COOLER HIGHS
AROUND 90 TO THE LOWER 90S. FAR EAST CENTRAL IA AND NW IL...IN THE
MODIFIED DRIER GREAT LAKES AIRMASS AND LIGHT EASTERLY WINDS...
HIGHS SHOULD BE LIMITED TO THE MID TO UPPER 80S WITH HEAT INDEX
VALUES FROM THE UPPER 80S TO LOWER 90S. THIS SUPPORTS THE CURRENT
HEAT ADVISORY AREA AND WILL BE KEEPING IT INTACT TODAY AND HAVE
EXPANDED INTO FRIDAY. CANNOT RULE OUT AN ISOLATED BRIEF SHOWER TO
BREAK THROUGH THE CAP ALONG THE BOUNDARY AS OCCURRED LATE
YESTERDAY...BUT DOES NOT LOOK WORTHY OF MENTION BEYOND A 10
PERCENT POP.
TONIGHT...DEWPOINTS WILL RECOVER BACK INTO THE UPPER 60S TO LOWER
70S OVER MOST OF THE AREA...SUPPORTING LOWS IN A RANGE FROM THE
UPPER 60S NORTHEAST TO MID 70S IN THE FAR SOUTH. ANY NOCTURNAL
CONVECTION IN THE NORTHERN PLAINS OR UPPER MS VALLEY SHOULD REMAIN
NORTH OF THE AREA AND HAVE A DRY FORECAST.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 343 AM CDT THU AUG 29 2013
FORECAST FOCUS ON A SCORCHER ON FRIDAY THEN STRONG COLD FRONT
ARRIVES ON SUNDAY ENDING THE HEAT WAVE.
FRIDAY THROUGH SATURDAY...COMPRESSIONAL HEATING AHEAD OF A WEAK COLD
FRONT WILL PUSH TEMPERATURES TO NEAR RECORD LEVELS AT SOME LOCATIONS
ON FRIDAY. 850 MB TEMPERATURES ARE PROGGED TO +22 TO 24C AND WITH A
CAPPED ATMOSPHERE SURFACE TEMPERATURES SHOULD SOAR INTO THE MID TO
UPPER 90S AT MANY LOCATIONS. COMBINED WITH DEWPOINTS AT LEAST IN THE
LOWER 70S THIS WILL CREATE HEAT INDEX VALUES OF 100 TO 107. THIS IS
THE REASON FOR EXTENDING THE HEAT ADVISORY TO 7 PM ON FRIDAY. HAVE
LEFT OUT OUR NORTHEAST COUNTIES FOR NOW AS SOME DEBATE ON THE
POTENTIAL FOR DEBRIS CLOUDS FROM A POSSIBLE MCS PUSHING ACROSS THE
GREAT LAKES. IF A FULLY SUNNY DAY IS EVIDENT THEN THE ADVISORY WILL
NEED TO BE ISSUED FOR OUR NORTHEAST CWA.
A SIGNIFICANT SHORT WAVE WILL BE MOVING ACROSS THE MIDWEST WHICH
WILL SEND A WEAK COLD FRONT INTO THE DVN CWA BY FRIDAY EVENING. THE
CAP SHOULD WEAKEN AS CONVECTIVE TEMPERATURES ARE REACHED BUT MODELS
DIFFER ON COVERAGE OF ANY CONVECTION. THE GFS IS MUCH MORE
AGGRESSIVE WITH INDICATING WIDESPREAD THUNDERSTORMS FRIDAY NIGHT BUT
THE ECMWF HINTS AT ONLY ISOLATED OR WIDELY SCATTERED COVERAGE. ANY
STORMS THAT DO FORM IN THE VERY UNSTABLE ATMOSPHERE MAY BE CAPABLE
OF ISOLATED DAMAGING WIND. FOR NOW WILL GO WITH A 30 PERCENT POP.
SPC HAS THE ENTIRE CWA IN A SEE TEXT WITH A 5% PROBABILITY OF SEVERE.
THE FRONT WILL STALL IN THE AREA ON SATURDAY KEEPING TEMPERATURES A
BIT LOWER WITH HIGHS RANGING FROM THE UPPER 80S NORTH TO MID 90S
SOUTH. THE HEAT ADVISORY MAY NEED TO BE EXTENDED IN OUR SOUTH ON
SATURDAY.
SUNDAY THROUGH NEXT WEEK...A STRONG COLD FRONT WILL SWEEP ACROSS THE
CWA ON SUNDAY BRINGING WITH IT A 30-40% CHANCE FOR THUNDERSTORMS.
THIS OCCURRING AS A DEEPENING TROUGH DIGS SOUTHEAST INTO THE MIDWEST
AND GREAT LAKES. THE TIMING WILL BE CRUCIAL TO COVERAGE AND
INTENSITY OF THE STORMS. IF THE FRONT CAN ARRIVE DURING THE
AFTERNOON THEN THE SEVERE WEATHER POTENTIAL WILL INCREASE. WITH THE
PASSAGE OF THE FRONT MUCH COOLER AND LESS HUMID AIR WILL MAKE FOR A
VERY PLEASANT LABOR DAY AND ALSO ON TUESDAY. HIGHS WILL BE IN THE
70S TO LOWER 80S AND LOWS IN THE 50S EARLY IN THE WEEK.
TEMPERATURES SHOULD WARM BACK INTO THE 80S NEXT WEDNESDAY AHEAD OF
ANOTHER STRONG COLD FRONT WHICH WILL THEN USHER ANOTHER FALL-LIKE
AIRMASS INTO THE MIDWEST FOR LATE IN THE WEEK. HOWEVER...MUCH OF NEXT
WEEK LOOKS DRY.
HAASE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 621 AM CDT THU AUG 29 2013
MOISTURE ASSOCIATED WITH A SURFACE BOUNDARY STALLED FROM NW TO SE
ACROSS IA AND IL WAS PRODUCING AREAS OF FOG AND STRATUS THIS
MORNING. THE NEW FORECASTS HAVE IFR CONDITIONS POSSIBLE AT ALL
SITES UNTIL ABOUT 15Z...THEN RETURNING TO VFR . THERE IS A LOW
POTENTIAL THAT LOW CLOUDS AND AT LIGHT FOG COULD HANG ON
LONGER...RESULTING IN MVFR AND POSSIBLE IFR CONDITIONS THROUGH
LATE MORNING. HOWEVER...BY AFTERNOON...CONFIDENCE IS HIGH THAT
CONDITIONS WILL BE VFR AT ALL SITES WITH LIGHT SOUTHEAST TO SOUTH
SURFACE WINDS. MVFR FOG WILL LIKELY REDEVELOP AFTER SUNSET.
&&
.CLIMATE...
ISSUED AT 343 AM CDT THU AUG 29 2013
RECORD HIGHS FOR AUGUST 29...
MOLINE.........97 IN 1984
CEDAR RAPIDS...97 IN 1925
DUBUQUE........99 IN 1984
BURLINGTON.....96 IN 1953
RECORD HIGHS FOR AUGUST 30...
MOLINE.........98 IN 1953 AND PREVIOUS YEARS
CEDAR RAPIDS...100 IN 1953
DUBUQUE........94 IN 1941 AND PREVIOUS YEARS
BURLINGTON.....102 IN 1947
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR BENTON-BUCHANAN-CEDAR-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR HANCOCK-HENDERSON-HENRY
IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR CLARK-SCOTLAND.
&&
$$
UPDATE...SHEETS
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...SHEETS
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS CARIBOU ME
635 AM EDT THU AUG 29 2013
.SYNOPSIS...
HIGH PRESSURE NORTH OF THE STATE WILL WILL KEEP IT DRY TODAY
ACROSS FAR NORTHERN MAINE. SHOWERS ACROSS CENTRAL AND INTERIOR
DOWNEAST MAINE WILL DIMINISH LATER TODAY. A FRONTAL BOUNDARY WILL
ADVANCE TOWARDS THE REGION FROM THE WEST LATE FRIDAY INTO THE
WEEKEND WITH MORE SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
CHALLENGING FCST THROUGH TODAY AT LEAST W/RAINFALL PLACEMENT.
630 AM UPDATE...
ADJUSTED THE PRECIP CHANCES BASED ON THE LATEST RADAR AND RUC
PLACEMENT OF THE RAINFALL. AREA OF RAIN HAS SHIFTED MORE ON A LINE
FROM NORTHERN SOMERSET COUNTY SE TOWARD LINCOLN AND DOVER-FOXCROFT
INTO THE BANGOR REGION. INCREASE PERCENTAGES TO 90% IN THESE AREAS
AND CARRIED THE MENTION OF PERIODS OF HEAVY RAINFALL ESPECIALLY
ACROSS LINCOLN AND DOVER-FOXCROFT. FURTHER NORTH ACROSS AROOSTOOK
COUNTY, IT IS PRETTY MUCH RAIN-FREE AS DRIER CONTINUES TO WORKS
ITS WAY S.
PREVIOUS DISCUSSION...
LATEST RADAR IMAGERY SHOWED A SWATH OF RAIN OCCURRING ACROSS THE
CENTRAL HIGHLANDS(MT. KATAHDIN AND MILLINOCKET) SE INTO WASHINGTON
COUNTY. LATEST MESO ANALYSIS SHOWED THIS RAINFALL LINING UP WELL A
STRONG THETA E GRADIENT IN THE LLVLS COUPLED TO LLVL CONVERGENCE.
1000-700 LAYER SHOWED SOME DEFORMATION BANDING TO ADD TO THIS PER
THE LATEST RUC W/UPPER LOW MOVING ACROSS THE CWA. RAIN SHIELD HAS
BEEN EXPANDING SOME INTO NORTHERN PISCATAQUIS AND SE AROOSTOOK
COUNTY. THE 12/00Z RUNS OF THE ECMWF DEPICTED THIS QUITE WELL AND
DECIDED TO BLEND THE ECMWF AND RUC FOR THE POPS AND PLACEMENT OF
RAIN THIS MORNING SHOWING 70-90% PRECIP CHANCES FOR THE
AFOREMENTIONED AREAS. ADDITIONAL RAINFALL OF UP TO .75 INCHES IS
POSSIBLE W/SOME LOCATIONS RECEIVING CLOSE TO AN INCH. A FLOOD
ADVISORY WAS ISSUED FOR THE MILLINOCKET AND BAXTER STATE PARK
REGION TO COVER THIS POTENTIAL. THE MILLINOCKET REGION HAS ALREADY
RECEIVED UP TO 1.5 INCHES OF RAIN SINCE WEDNESDAY AFTERNOON.
FURTHER NORTH, DRIER AIR WAS WEDGING DOWN FROM SE CANADA W/HIGH
PRES NOSING IN. THEREFORE, THERE WILL BE SHARP CUTOFF OF PRECIP
BOTH NORTH AND WELL TOWARD THE BANGOR AND BAR HARBOR REGIONS.
TEMPERATURES WILL BE A TOUGH CALL TODAY DEPENDING ON WHERE THE SUN
WILL BREAK OUT AND THIS LOOKS TO MOST LIKELY ACROSS THE DOWNEAST
AND SWRN AREAS. OTHERWISE, NE FLOW WILL KEEP CLOUDS AROUND MUCH OF
THE DAY LIMITING HEATING AS SEEN FROM THE LATEST IR SATL SHOWING
CLOUDS FILLING BACK IN EVEN ACROSS THE CROWN OF MAINE. THEREFORE,
AFTERNOON MAXES WILL STRUGGLE TO GET THROUGH THE UPPER 60S TODAY
ACROSS MUCH OF THE REGION W/THE EXCEPTION OF THE INTERIOR
DOWNEAST(BANGOR AREA) AS TEMPERATURES ARE EXPECTED TO CLIMB INTO
THE LOWER 70S. STILL BELOW NORMAL FOR LATE AUGUST.
THINGS ARE EXPECTED TO DRY OUT AS LOW PRES PULLS AWAY AND HIGH
PRES RIDGES IN FROM THE WEST. DECIDED TO STAY CLOSE TO THE
DAYCREW`S OVERNIGHT LOWS W/READINGS DROPPING INTO THE UPPER 40S
NORTH AND LOW TO MID 50S CENTRAL AND DOWNEAST AREAS. ADDED PATCHY
FOG FOR LATE TONIGHT W/THE CLEARING AND WET GROUND FROM THE
RAINFALL. CENTRAL AND INTERIOR DOWNEAST WILL BE MOST PRONE TO THE
FOG DEVELOPMENT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
LOW PRESSURE ACROSS THE GREAT LAKES FRIDAY WILL BE MOVING SLOWLY
EAST AND A WEAK FRONTAL BOUNDARY WILL ALSO BE MOVING EAST. CLOUDS
WILL ONCE AGAIN BE ON THE INCREASE WITH THE CHANCE OF AN ISOLATED
SHOWER ACROSS WESTERN AND NORTHERN AREAS. THE FRONTAL BOUNDARY IS
THEN EXPECTED TO SET UP SOMEWHERE ACROSS CENTRAL OR NORTHERN MAINE
FRI NIGHT INTO SAT INCREASING THE CHANCE OF SHOWERS...ESPECIALLY
DURING THE AFTERNOON SATURDAY. OTHERWISE...IT IS EXPECTED TO MUGGY
WITH PATCHY FOG FRI NIGHT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE WEATHER PATTERN CAN BE SUMMED UP AS HIGHLY UNSETTLED. AN UPPER
TROUGH NEAR LAKE WINNEPEG SATURDAY EVENING IS EXPECTED TO AMPLIFY AS
IT MOVES EAST AND RE-ESTABLISH AN EAST COAST TROUGH...A PATTERN SEEN
OFTEN THIS SUMMER. THIS PATTERN WILL PRODUCE A MOIST SOUTHWEST FLOW
ALOFT AHEAD OF THE UPPER TROUGH WITH A SERIES OF SHORTWAVES TO
TRAVERSE THE AREA SUN THROUGH TUE. MUCH OF THE TIME IS LIKELY TO BE
CLOUDY AND MUGGY WITH OCCASIONAL BOUTS OF SHOWERS. IT IS IMPOSSIBLE
AT THIS TIME FRAME TO TIME OUT INDIVIDUAL SHORTWAVES SO WILL HAVE TO
HAVE A BROAD BRUSH OF HIGH CHANCE POPS THOUGH MUCH OF THE PERIOD
WITH THE UNDERSTANDING THAT LIKELY OR EVEN CATEGORICAL POPS WILL
BE NEEDED FOR SOME FORECAST PERIODS DOWN THE ROAD. THE AIR MASS
WILL FEATURE DAYTIME HIGHS WILL BE CLOSE TO NORMAL WITH LOWS WELL
ABOVE NORMAL IN THE MUGGY AIR MASS. IT MAY NOT BE UNTIL SOMETIME
LATE NEXT WEEK THAT THE TROUGH AXIS IS ABLE TO FINALLY PUSH EAST
OF THE AREA WITH SOME DRIER AIR.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
NEAR TERM: IFR/MVFR THIS MORNING ACROSS ALL TERMINALS IMPROVING TO
VFR LATER TODAY INTO THE EVENING. THERE IS POTENTIAL FOR MVFR
CONDITIONS DUE TO SOME FOG DEVELOPMENT LATER TONIGHT.
SHORT TERM: MAINLY VFR FRI OUTSIDE OF ANY PATCHY EARLY MORNING FOG.
CONDITIONS ARE EXPECTED TO LOWER FRI NIGHT TO IFR/MVFR IN STRATUS
AND PATCHY FOG...WITH MVFR MUCH OF THE TIME SAT THROUGH MON WITH
OCCASIONAL IFR.
&&
.MARINE...
NEAR TERM: NO HEADLINES ATTM. SOME CONCERN ABOUT WINDS THIS
MORNING AS THE GRADIENT HAS TIGHTENED A BIT MORE THAN WHAT THE
PREVIOUS GUIDANCE WAS SHOWING. 44027 WAS SUSTAINED AT 20 KTS
W/GUSTS TO 25 KT. CLOSER INTO THE INTRA-COASTAL ZONE, WINDS AROUND
15KT. USING A BLEND OF THE NAM12 AND GFS40 WINDS, DECIDED TO ADD
GUSTS TO 25 KT FOR THE OUTER ZONES TO ACCOUNT FOR THE STRONGER
PRES GRADIENT THIS MORNING AS LOW PRES PULLS NNE ACROSS THE NW
ALTC. THIS WILL NEED TO BE MONITORED FOR A POSSIBLE SCA IF WINDS
STAY UP LONGER. SEAS ARE HOLDING AT 2-4 FT AND KEPT SEAS IN THIS
RANGE THROUGH TONIGHT.
SHORT TERM: THE WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SCA LEVELS
THROUGH THE WEEKEND. A LONGER SLY FETCH IS EXPECTED TO DEVELOP
EARLY NEXT WEEK AS AN AREA OF LOW PRESSURE TO THE WEST OF THE WATERS
MOVES NORTH OF THE REGION TUESDAY. THERE IS THE POTENTIAL THAT SEAS
MAY APPROACH SCA LEVELS MON-TUE.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT
SHORT TERM...CB
LONG TERM...CB
AVIATION...HEWITT/CB
MARINE...HEWITT/CB
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
943 AM EDT THU AUG 29 2013
.SYNOPSIS...
A FRONTAL BOUNDARY SHIFTS SOUTH INTO NORTH CAROLINA BY LATE THIS
MORNING. WEAK HIGH PRESSURE SHOULD BUILD INTO THE AREA BEHIND IT
FOR THURSDAY AFTERNOON INTO FRIDAY BEFORE SLIDING OFFSHORE BY SATURDAY.
THIS WILL BRING A RETURN FLOW OF MOISTURE ALONG WITH AN ASSOCIATED
WARM FRONT LATER IN THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 940 AM EDT THURSDAY...
THIS MORNING 8AM/12Z RNK SOUNDING SHOWED PLENTY OF MOISTURE
UP TO 640 MB WITH A NORTHERLY FLOW. KFCX 88D INDICATED WIDELY
SCATTERED SHOWERS TRAVELING SOUTH THIS MORNING. COLD FRONT ACROSS
SOUTHERN PORTIONS OF CWA THIS MORNING WILL SLOWLY DRIFT SOUTH
TODAY. MADE SOME ADJUSTMENTS IN THE POPS TO SHAPE TOWARDS RADAR
TRENDS AND HRRR FOR NEXT COUPLE OF HOURS...THEN KEPT THE SCATTERED
STORMS IN FOR THE AFTERNOON INTO TONIGHT. THE BEST CHANCE REMAIN
ALONG THE SOUTHERN BLUE RIDGE THIS AFTERNOON WITH MOISTURE
CONVERGENCE. HIGH PRESSURE BUILDS SOUTH ACROSS THE REGION
TONIGHT. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE
UPPER 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONT.
AS OF 315 AM EDT THURSDAY...
SOUPY AIRMASS IN PLACE THIS MORNING WITH TEMPS STILL RUNNING IN THE
70S OVER MUCH OF THE AREA. FRONTAL BOUNDARY SITUATED FROM LOW
PRESSURE OVER VA TIDEWATER NORTHWEST INTO NRN WV THEN INTO SRN
OHIO. HIGHER THETA-E ACROSS ERN KY/SRN WV SHIFTING SE INTO THE NC
MTNS WILL KEEP SHOWERS AROUND THRU AT LEAST MID MORNING...BUT
MAINLY ISOLATED.
AT THE MOMENT SKIES HAVE CLEARED OVER THE FOOTHILLS AND PIEDMONT
THANKS TO A CONSISTENT NNW FLOW DOWNSLOPING WIND. THIS WILL CHANGE
THRU DAYBREAK AS THE FLOW COMES AROUND TO THE NORTH THEN NORTHEAST.
STILL HINGING ON CLOUDS INCREASING ALONG THE BLUE RIDGE AND POINTS
EAST BUT THEN SLOWLY MIXING OUT TOWARD MIDDAY. THE 00Z CMC HAS A
PRETTY GOOD HANDLE EARLY...BUT DOES NOT REALLY ENHANCE LOW CLOUDS
DEVELOPING OVER THE BLUE RIDGE LIKE THE NAM DOES...SO LEANED TOWARD
A BLEND OF THE TWO.
THROUGH THE DAY...WILL BE DEALING WITH SOME DRYING ALOFT...BUT
KEEPING THE LOW LVLS MOIST...AS NOT MUCH CHANGE IN AIRMASS EXPECTED.
THERE WILL BE ENOUGH LOW LEVEL CONVERGENCE AROUND NEAR THE FRONT
THAT AT LEAST ISOLATED SHOWERS OR STORMS OCCUR THIS AFTERNOON. STILL
LOOKS LIKE THE SRN BLUE RIDGE HAS THE BEST CHANCE OF SEEING
SCATTERED COVERAGE GIVEN THE FORECAST CONVERGENCE PATTERN IN THE
WINDS.
GIVEN A LACK OF UPSTREAM CONVECTION AND CLOUDS...THINK THE SUN WILL
BREAK THROUGH TOWARD EARLY AFTERNOON IN THE NORTH...THEN MID
AFTERNOON ELSEWHERE. THESE LOWER CLOUDS MAY BE HARD TO MIX OUT UNTIL
LATE MORNING. FOR THE AFTERNOON ENOUGH SUN WILL AVAILABLE TO REALIZE
WARMER HIGHS...BUT SOUPY AIRMASS WILL STILL CUT INTO REALLY WARM
TEMPS...SO WENT CLOSE TO OR JUST BELOW MAV MOS WITH UPPER 70S/LOWER
80S WEST TO MID TO UPPER 80S ACROSS THE SOUTHERN SHENANDOAH
SOUTHEAST INTO SOUTHSIDE VA AND THE NC PIEDMONT/FOOTHILLS.
LOW LVLS WINDS CONTINUE TO SHIFT TOWARD THE EAST THEN SOUTHEAST LATE
TONIGHT AS HIGH PRESSURE NOSES SOUTH OVER THE ALLEGHANY HIGHLANDS.
STILL ENOUGH CONVERGENCE AND LOW LVL MOISTURE TO HANG ONTO POPS OF
THE 20/30 VARIETY OVER THE SOUTHERN BLUE RIDGE AND ADJACENT AREAS
THIS EVENING...GRADUALLY SHRINKING TO SLIGHT CHANCE OVER THE NC MTNS
AFTER MIDNIGHT. ENOUGH DRY AIR MAY ALLOW TEMPS TO FALL IN THE NRN
CWA TO THE LOWER 60S TONIGHT...WITH MID TO UPPER 60S PREVALENT
ELSEWHERE.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 400 AM EDT THURSDAY...
THE STRONG UPPER HIGH OVER THE MIDWEST WILL WEAKEN AS IT MOVES TO
THE FOUR CORNERS REGION LATE THIS WEEKEND. AS HEIGHTS LOWER OVER THE
SOUTHEASTERN/GULF COAST STATES...AND AN UPPER TROUGH STRENGTHENS
OVER THE GREAT LAKES...SOUPY HIGH PWAT AIR WILL BE FORCED NORTH FROM
THE GULF OF MEXICO AS WINDS BECOME S AND SW EVENTUALLY. BEFORE
THIS...JUST GARDEN VARIETY STORMS ACROSS EXTREME SW VA AND NW NC FOR
FRIDAY. GOOD UPSLOPE COMPONENT MOST OF THE DAY MAY KEEP SPOTS ALONG
THE SOUTHERN HALF OF THE BLUE RIDGE BELOW 80F. ALTHOUGH BOTH
SATURDAY AND SUNDAY HAVE THE POTENTIAL FOR SLOW MOVING STORMS AND
WATER PROBLEMS...ESPECIALLY ACROSS NW NC...AN UPPER WAVE WILL BE
INVOLVED SUNDAY WHICH SHOULD INCREASE COVERAGE. DESPITE A LOT OF
CLOUDS AND STORMS AROUND...H85 TEMPS IN THE UPPER TEENS WILL STILL
GET SOME SPOTS INTO THE MID 80S. STORMS WILL PROBABLY MORE SCATTERED
ACROSS THE SOUTHSIDE AND NC PIEDMONT THIS WEEKEND...SUCH THAT UPPER
80S MAY BE POSSIBLE THERE. ELSEWHERE...GUIDANCE TEMPS WILL PROBABLY
CONTINUE THEIR CURRENT WARM BIAS SO WENT A FEW DEGREES BELOW ON MAX
T EVERYWHERE ELSE.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 245 PM EDT WEDNESDAY
THE GFS/ECMWF/CANADIAN/GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT THAT
THE UPPER TROF...WHICH HAS BEEN PERSISTENT ACROSS THE EASTERN U.S.
FOR MOST OF THE SUMMER...AMPLIFIES BY EARLY NEXT WEEK.
THERE ARE SOME MINOR DIFFERENCE WITH REGARD TO AMPLIFICATION WITH
THE ECMWF FORECASTING A SLIGHTLY DEEPER/SLOWER EASTERN U.S. TROF
COMPARED TO THE GFS AND CANADIAN MODELS. WITH THE BLOCKY
PATTERN...LEANED TOWARD THE STRONGER ECWMF SOLUTION.
AS THE UPPER TROF DEEPENS...A STRONG COLD FRONT WILL PUSH THROUGH
MONDAY NIGHT/EARLY TUESDAY BRINGING COOLER TEMPS...DRIER
WEATHER...AND LOWER DEW POINTS FOR TUESDAY AND WEDNESDAY.
BEFORE THE FRONTAL PASSAGE...DIURNALLY DRIVEN SHOWERS AND STORMS
WILL BE FOUND SUNDAY AND MONDAY. LOCALLY HEAVY RAIN WILL BE POSSIBLE
AS PWATS WILL BE 1-2 STANDARD DEVIATIONS ABOVE NORMAL PER THE GEFS.
FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WENT BELOW GFS MOS
GUIDANCE FOR TEMPS WITH THE GEFS SHOWING 850MB TEMPS 1-2 STANDARD
DEVIATIONS BELOW NORMAL.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
AS OF 730 AM EDT THURSDAY...
IFR/MVFR CIGS/VSBYS WILL BE SLOW TO ERODE THIS MORNING AS THE FLOW
TURNS SLOWLY NORTH THEN NORTHEAST. A FEW SHOWERS FROM LYH TO NORTH
OF ROA SO KEEPING SOME VCSH IN AT THESE SITES AS WELL AS DAN BUT
NOT EXPECTING ANYTHING TOO HEAVY.
NOT MUCH CHANGE FROM PREVIOUS FORECAST AS EXPECT GRADUAL TREND TO
VFR BY EARLY AFTERNOON BUT SKIES STAYING BKN V SCT.
MOST OF THE SHOWER/STORMS THIS AFTERNOON WILL BE CONFINED TO THE
SOUTHERN BLUE RIDGE SOUTH OF ROA/BCB AND SOUTH OF BLF. THEREFORE
LEAVING ANY MENTION OUT OF THE TAFS GIVEN THREAT IS 20 PERCENT OR
LESS.
THIS EVENING...THE HIGH PRESSURE BEHIND THE FRONT MOVES IN AND
SKIES SHOULD CLEAR ENOUGH FOR FOG TO FORM AT MOST STATIONS. DENSE
FOG WILL OCCUR AT LWB/BCB WITH IFR VSBYS AT LYH. MAYBE SOME LOWER
CLOUDS MVFR AT ROA/DAN AND IFR AT BLF.
FOG/LOW CLOUDS ERODE FRIDAY MORNING...WITH A RETURN TO OVERALL
VFR CONDITIONS UNDER HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS
AT BEST FRIDAY AFTERNOON AND SATURDAY. DEEPER MOISTURE WILL MAKE A
RETURN LATER IN THE WEEKEND WITH MORE IN THE WAY OF CONVECTIVE
DRIVEN SUB-VFR CONDITIONS POSSIBLE WITH A PASSING WARM FRONT
SUNDAY...AND ANOTHER COLD FRONT LATER MONDAY. OTHERWISE SOME
PATCHY FOG LIKELY DURING THE OVERNIGHTS INTO SATURDAY...WITH LATE
NIGHT/EARLY MORNING MVFR/IFR CONDITIONS POSSIBLE ESPECIALLY AT THE
VALLEY LOCATIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP
NEAR TERM...KK/WP
SHORT TERM...KM
LONG TERM...PH
AVIATION...JH/KK/WP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
643 AM CDT THU AUG 29 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT THU AUG 29 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST...STRONG SUBTROPICAL
RIDGING OVER THE CENTRAL PLAINS AND TROUGHING ALONG THE EAST COAST
OF THE U.S.. ROUNDING THE SUBTROPICAL RIDGE WAS A CLUSTER OF
SHORTWAVES OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA.
SHOWERS AND THUNDERSTORMS HAVE BEEN ACCOMPANYING THESE SHORTWAVES...
WHICH ALSO ARE BEING AIDED BY MOISTURE TRANSPORT FROM SOUTHERLY
20-30 KT 850MB WINDS PER RADAR VWP DATA ACROSS THE WESTERN DAKOTAS.
EASTERN EXTENT OF THIS MOISTURE TRANSPORT HAS PRODUCED SOME STORMS
NEAR FARGO. FARTHER EAST OVER THE FORECAST AREA...CONDITIONS HAVE
REMAINED DRY THUS FAR DUE TO LITTLE IF ANY FORCING AS WELL AS STILL
SOME DRY AIR ABOVE THE SURFACE LINGERING AROUND AS SEEN IN THE 00Z
MPX SOUNDING. SURFACE MOISTURE REMAINS HIGH...ESPECIALLY OVER
NORTHERN IOWA AND SOUTHERN MN WHERE DEWPOINTS ARE IN THE LOW 70S.
THIS HIGHER MOISTURE IS POOLED ALONG A WARM FRONTAL BOUNDARY
BISECTING IOWA NORTHWEST TO SOUTHEAST. AIRMASS REMAINS WARM ACROSS
THE UPPER MIDWEST...WITH 925MB TEMPS AT 00Z RANGING FROM 22C AT
GRB...TO 25C AT MPX AND DVN...AND 27-29C AT ABR...BIS AND OAX.
..HAZARDS..
1. HEAT. HEAT INDICES ARE AGAIN EXPECTED TO CLIMB INTO THE 90 TO 100
RANGE...HIGHEST IN NORTHEAST IOWA...BUT STILL NOT HIGH ENOUGH TO
WARRANT A HEAT ADVISORY MENTION.
2. STORMS. BULK OF THE STORM ACTION IS EXPECTED NORTH OF THE
FORECAST AREA THROUGH TONIGHT. HOWEVER...THERE IS A SMALL CHANCE
SOME OF THE STORMS COULD ROLL THROUGH LOCATIONS NORTHEAST OF I-94
TONIGHT AND PRODUCE LARGE HAIL AND DAMAGING WINDS.
..SYNOPTIC OVERVIEW..
29.00Z MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A RETROGRESSION
WESTWARD OF THE SUBTROPICAL RIDGE INTO COLORADO BY 12Z FRIDAY.
MEANWHILE...THE CLUSTER OF SHORTWAVES PRESENTLY TOPPING THE GENERAL
RIDGING ARE PROGGED TO CONTINUE MARCHING EAST...REACHING LAKE
SUPERIOR AND UPPER MICHIGAN BY 12Z FRIDAY. AS THESE SHORTWAVES PRESS
EAST...THE WARM FRONTAL BOUNDARY IN IOWA GETS LIFTED NORTHEAST...
PERHAPS ALL THE WAY INTO UPPER MI BY 12Z FRIDAY. ADDITIONALLY...ALL
INDICATIONS ARE THAT A LOW PRESSURE AREA WILL ACCOMPANY THE
SHORTWAVES...WHICH IS ALREADY EVIDENT OVER FAR SOUTHWEST NORTH
DAKOTA.
..DETAILS..
29.00Z MODEL GUIDANCE HAS DEFINITELY TRENDED DRIER FOR THE FORECAST
AREA FOR BOTH TODAY AND TONIGHT...A TREND THAT STARTED WITH THE
28.12Z MODEL GUIDANCE AND PREVIOUS FORECAST. IN FACT...THE 29.00Z
REGIONAL CANADIAN IS COMPLETELY DRY. CERTAINLY GIVEN THE TRACK OF
THE SHORTWAVES AND SURFACE LOW...CONFIDENCE IS VERY HIGH THAT
LOCATIONS NORTH OF HERE FROM NORTHERN MN THROUGH NORTHWEST WI AND
UPPER MI WILL SEE SHOWERS AND STORMS. THE ONLY QUESTION MARK IS IF
THE WARM FRONT LIFTING THROUGH THE AREA CAN SPARK ANY CONVECTION...
EITHER DRIVEN BY 310-315K ISENTROPIC LIFT / 850MB MOISTURE
TRANSPORT...OR THROUGH SURFACE BASED CONVECTION. THERE IS A THIRD
SCENARIO PRESENTED BY THE 29.00Z NAM...WHERE SOME OF THE CONVECTION
COMING OUT OF NORTH DAKOTA THIS MORNING ROLLS DOWN ALONG THE
FRONT...IMPACTING LOCATIONS ALONG/WEST OF THE MS RIVER. HOWEVER...
HRRR TRENDS SUGGEST THIS WILL NOT HAPPEN...WHICH MAKES SENSE TOO AS
THE STRONGEST LOW LEVEL MOISTURE TRANSPORT REMAINS AIMED NORTHWEST
AND NORTH OF THE AREA. CHECKING OUT SURFACE BASED CONVECTION
POTENTIAL...MODIFYING A VARIETY OF SOUNDINGS FROM THE RAP AS WELL AS
THE 29.00Z GFS ALL SHOW A CAP HOLDING IN PLACE...LOCATED AROUND
775MB. THIS CAP ORIGINATES FROM WARM AIR BEING ADVECTED IN SOUTH OF
THE SHORTWAVE TRACK. IMPRESSIVE TO SEE THAT ALL OF TODAY THE 29.00Z
GFS DOES NOT PRODUCE ANY PRECIPITATION...WHICH THAT SIGNAL ALONE
LENDS MORE CONFIDENCE TO A DRY FORECAST. TO HELP BLEND WITH
NEIGHBORING OFFICES TO THE NORTH...HAVE MAINTAINED 20 PERCENT
CHANCES ACROSS FAR NORTHERN PORTIONS OF THE FORECAST AREA.
AS WE HEAD INTO TONIGHT...THE 29.00Z GFS/NAM/ECMWF INDICATE
POTENTIAL FOR SOME CONVECTION NORTHEAST OF I-94 AS THE LOW LEVEL JET
STRENGTHENS. FEEL IT IS PRUDENT TO HAVE A 20-40 PERCENT CHANCE IN THIS
AREA. OTHERWISE CAPPING AND DRY CONDITIONS SHOULD DOMINATE THE REST
OF THE FORECAST AREA.
MUCH OF THE WARM ADVECTION TODAY OCCURRING SOUTH OF THE TRACK OF THE
SHORTWAVES IS PROGGED TO OCCUR UP IN THAT 700-800MB LAYER. 925MB
TEMPERATURES REALLY DO NOT RESPOND IN OUR FORECAST AREA UNTIL AFTER
00Z. 925MB READINGS ARE PROGGED VERY SIMILAR TO YESTERDAY...
THEREFORE...ANTICIPATING SIMILAR HIGHS. WITH DEWPOINTS RUNNING IN
THE UPPER 60S TO MID 70S...WE SHOULD SEE YET AGAIN ANOTHER DAY OF
HEAT INDICES IN THE 90-100 RANGE...HIGHEST OVER NORTHEAST IA WHERE
HIGHEST TEMPERATURES AND DEWPOINTS ARE EXPECTED. ANOTHER WARM NIGHT
ON TAP TONIGHT AS WARMER 925MB SURGES IN AND DEWPOINTS REMAIN UP.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM CDT THU AUG 29 2013
..HAZARDS..
1. HEAT. HEAT INDICES HAVE COME DOWN SLIGHTLY ACROSS NORTHEAST IOWA
FOR FRIDAY...NOW IN THE 95-100 RANGE. SATURDAY HAS ALSO COME
DOWN...NOW MOSTLY AT OR BELOW 90. SO IT IS POSSIBLE NOW THAT WE CAN
GET THROUGH LABOR DAY WEEKEND WITHOUT ANY HEAT ADVISORIES...A BIG
CHANGE FROM WHAT THINGS LOOKED LIKE 4-7 DAYS AGO.
..SYNOPTIC OVERVIEW..
FOCUS FOR MUCH OF THE LONG TERM PERIOD IS THE IMPACT THE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST WILL HAVE ON THE FORECAST
AREA. THIS TROUGH IS PROGGED TO BEGIN EJECTING OUT ON FRIDAY...
CAUSING RIDGING TO BUILD OVER THE NORTHERN PLAINS...AND IN RESPONSE
TURNING THE UPPER FLOW MORE NORTHWESTERLY OVER THE FORECAST AREA.
THIS NORTHWEST FLOW WILL HELP DRIVE A COLD FRONT THROUGH THE AREA ON
FRIDAY. HEADING INTO THE WEEKEND...THE TROUGH IS EXPECTED TO MARCH
ACROSS SOUTHERN CANADA...WITH GOOD MODEL AGREEMENT FOR IT TO DIG
INTO THE WESTERN GREAT LAKES REGION ON SUNDAY. A WARM FRONTAL
PASSAGE IS LIKELY AHEAD OF THE TROUGH LATE SATURDAY...FOLLOWED BY A
FAIRLY STRONG COLD FRONTAL PASSAGE SUNDAY MORNING. ALL INDICATIONS
ARE THAT THIS TROUGH WILL EVENTUALLY ENCOMPASS MUCH OF THE EASTERN
THIRD OF THE U.S. BY TUESDAY...ALLOWING HIGH PRESSURE TO COME INTO
THE FORECAST AREA AT THE SURFACE. THE FORECAST BEYOND TUESDAY IS
MORE UNCERTAIN...PARTICULARLY DRIVEN BY THE ECMWF WHICH SHOWS A VERY
POTENT NORTHERN STREAM SHORTWAVE TROUGH DROPPING DOWN INTO THE
WESTERN GREAT LAKES REGION ON WEDNESDAY. THE 29.00Z GFS/CANADIAN
SHOW THIS SAME FEATURE TOO...BUT KEEP IT MORE PROGRESSIVE AND
IMPACTING SOUTHEAST CANADA INSTEAD. THE TWO SCENARIOS ARE
DRAMATICALLY DIFFERENT WHEN IT COMES TO BOTH PRECIPITATION AND
TEMPERATURE FORECASTS.
..DETAILS..
WITH A COLD FRONT COMING THROUGH ON FRIDAY...THERE ARE QUESTIONS ON
CAN IT PRODUCE ANY PRECIPITATION...AS WELL AS ITS TIMING FOR IMPACT
ON TEMPERATURES. MODELS HAVE DEFINITELY SPED UP ON THE COLD FRONTAL
TIMING...ESPECIALLY THE 29.00Z ECMWF/CANADIAN...HAVING IT NOW REACH
DVN BY 00Z SATURDAY. IF THIS TREND CONTINUES...WE MAY NOT HAVE ANY
CONVECTION ON FRIDAY. HOWEVER...THE 29.00Z GFS/REGIONAL CANADIAN/NAM
DEPICT A SLOWER TIMING...SO HAVE KEPT SOME 20-30 PERCENT CHANCES
GOING FOR NOW. THE SPEEDING UP OF THE FRONT ALSO HELPS TO PUSH THE
SURGE OF WARM AIR COMING IN HERE TONIGHT SOUTHEAST QUICKER. AS A
RESULT...HIGHS HAVE BEEN LOWERED SLIGHTLY...WHICH ALSO LOWERS HEAT
INDICES.
MAINLY DRY CONDITIONS LOOK TO PREVAIL FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BECOMES FIRMLY IN CONTROL. LOWERED TEMPERATURES A
BIT DURING THIS PERIOD AS THE AIR COMING IN IS A LITTLE COOLER THAN
PREVIOUSLY FORECAST.
THE WARM AIR SURGE AS WELL AS MOISTURE TRANSPORT AHEAD OF THE POTENT
SHORTWAVE CROSSING SOUTHERN CANADA COMES ACROSS THE AREA SATURDAY
NIGHT. 29.00Z GFS/ECMWF/NAM/CANADIAN ARE ALL IN GOOD AGREEMENT
SHOWING SOME SHOWERS AND THUNDERSTORMS IN THIS WARM ADVECTION SURGE
COMING INTO THE FORECAST AREA...ESPECIALLY AFTER MIDNIGHT. RAISED
CHANCES TO 40-50...HIGHEST OVER WESTERN PORTIONS OF THE FORECAST
AREA. SOME OF THESE CHANCES PERSIST INTO SUNDAY WITH THE COLD FRONT
COMING THROUGH. AS IT STANDS RIGHT NOW...THE BULK OF THE COLD
ADVECTION BEHIND THE FRONT APPEARS TO WAIT UNTIL AFTER SUNSET SUNDAY.
BEYOND SUNDAY...HIGH PRESSURE DOMINATES FOR THE MOST PART EXCEPT FOR
POSSIBLY A COLD FRONTAL PASSAGE ON WEDNESDAY PER 28.12Z/29.00Z
ECMWF. BOTH ECMWF MODELS SUGGEST THE FRONT WILL HAVE LITTLE MOISTURE
TO WORK WITH SO IT COMES THROUGH DRY. THEREFORE...DRY CONDITIONS ARE
FORECAST BEYOND SUNDAY. THE BIGGER THING WILL BE TEMPERATURES. 925MB
TEMPS PLUMMET FROM 22-25C ON SATURDAY...TO 18-22C ON SUNDAY...AND
14-17C ON MONDAY. GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
POSSIBLY WEDNESDAY AS WELL...DEPENDING ON IF THAT COLD FRONT COMES
THROUGH OR NOT. LAST NOTE WOULD BE POTENTIAL FOR VALLEY FOG TUESDAY
MORNING...BUT TOO EARLY TO PUT THAT IN THE FORECAST AT THIS TIME
GIVEN HOW SENSITIVE VALLEY FOG CAN BE TO OTHER VARIABLES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 642 AM CDT THU AUG 29 2013
MVFR CLOUDS DEVELOPED ALONG THE INTERSTATE 90 CORRIDOR OVERNIGHT.
THESE CLOUDS ARE AFFECTING KLSE AND VERY NEAR KRST. HRRR AND RAP
SUGGEST THAT THESE CLOUDS WILL DISSIPATE BETWEEN 29.15Z AND
29.17Z. A WARM FRONT WILL PRODUCE A BROKEN DECK OF 5K FOOT CLOUD
BETWEEN 29.21Z AND 30.03Z AT BOTH TAF SITES. THERE MAY BE SOME
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THIS FRONT...BUT IT
LOOKS LIKE THE CAP WILL BE STRONG TO PROHIBIT THEM FROM OCCURRING
AT THE TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
326 PM MDT THU AUG 29 2013
.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 242 PM MDT THU AUG 29 2013
SHOWERS AND STORMS DEVELOPED AS EXPECTED AROUND 18Z OVER THE FAVORED
HIGHER TERRAIN AREAS PARTICULARLY THE ABAJOS...SAN JUANS...AND
FLATTOPS. THE 12Z GJT SOUNDING SHOWED PW VALUES OF 0.95 INCHES
WHICH IS MATCHING UP QUITE WELL WITH THE RAP AND THE NAM MODELS.
THE GFS PWATS WERE MUCH LOWER SO THINKING THE GFS IS UNDERPLAYING
THE AMT OF MOISTURE. WITH HIGH PRESSURE OVERHEAD...LIGHT STEERING
FLOW WILL LEAD TO STORMS STAYING RELATIVELY ANCHORED TO THE
TERRAIN WITH LITTLE MOVEMENT. SIMILAR PATTERN TO YESTERDAY...SO
EXPECT MUCH OF THE SAME WITH CONVECTION ENDING SHORTLY AFTER
SUNSET AND SOME STORMS LINGERING TILL MIDNIGHT. BIGGEST CONCERN
FOR THE REST OF THIS AFTERNOON INTO THE EVENING IS ANY STORMS THAT
FORM OVER ALREADY SATURATED AREAS...ESPECIALLY THE SAN JUANS WHERE
FLOODING OCCURRED YESTERDAY IN OURAY AND OVER RED MOUNTAIN PASS.
THE 12Z NAM SEEMS TO BE HANDLING THE MOISTURE BETTER THAN THE GFS SO
LEANING TOWARDS IT FOR FRIDAY. PW VALUES STAY RELATIVELY THE SAME
AT 0.9 INCHES ACROSS MUCH OF WESTERN COLORADO. HOWEVER PWATS
INCREASE SOME OVER SE UTAH...WITH SOME OF THE DEEPER MOISTURE
ASSOCIATED WITH THE INVERTED TROUGH OVER AZ AND SOCAL CREEPING INTO
SE UTAH WHERE PWATS INCREASE TO A LITTLE OVER AN INCH. AN ACTIVE
NORTHERN STREAM CAUSES THE RIDGE TO FLATTEN A LITTLE WHICH LAYS A
55KT JET MAX OVER THE CO-WY BORDER. IN ADDITION TO THIS...850-700MB
STREAMLINES SHOW A LOW LEVEL CONVERGENCE SIGNATURE THAT MOVES
THROUGH SE UTAH AND SW COLORADO FRIDAY AFTERNOON...WITH UPPER LEVEL
DIVERGENCE AS INDICATED IN DIVQ FIELDS. THINKING THAT FRIDAY MAY BE
A LITTLE MORE ACTIVE AND WIDESPREAD IN TERMS OF CONVECTION AS THERE
IS SOME LOW LEVEL AND UPPER LEVEL SUPPORT AND SEVERAL STRONG VORT
MAXES THAT MOVE THROUGH THE FLOW THAT CAN ACT AS A TRIGGER ON THE
MOISTURE. THINK THERE WILL BE ENOUGH SFC HEATING TO GET THINGS
GOING AGAIN AS SKIES BEGIN RELATIVELY CLEAR FRIDAY MORNING.
CONVECTION WILL BEGIN FRIDAY AFTERNOON OVER THE HIGHER TERRAIN WITH
SOME STORMS FORMING OVER THE VALLEYS LATER IN THE DAY AS
DISTURBANCES AND BOUNDARIES INTERACT GIVEN THE ADDITIONAL FORCING.
THINGS SHOULD WIND DOWN AFTER SUNSET AGAIN WITH SOME STORMS
LINGERING UNTIL MIDNIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 242 PM MDT THU AUG 29 2013
THE UPPER RIDGE STAYS CENTERED OVER THE FOUR CORNERS ON SATURDAY FOR
ANOTHER DAY OF MAINLY AFTERNOON THUNDERSTORMS OVER ELEVATED
LOCATIONS AS SUFFICIENT 0.60 TO 1.00 PWATS REMAIN TRAPPED UNDER
THE RIDGE...WITH THE DRIEST IN NORTHERN AREAS. THINKING THAT THE
NORTHERN UT/CO BORDER WILL SEE SOME BETTER ORGANIZED/LONGER LIVING
STORMS DESPITE THE LOWER BUT STILL GOOD ENOUGH AVAILABLE MOISTURE
SATURDAY AS THE MODELS INDICATE A MODERATE 40-50 KT SPEED MAX AT
250 MB. SE UTAH AND THE SAN JUANS OF COLORADO WILL REMAIN THE MOST
LIKELY LOCATION FOR STORM DEVELOPMENT WITH HEAVY RAIN AS THE
BIGGEST THREAT. IN SOUTHERN AREAS WITH LOW SHEER...CELLS WILL LIKELY BE
SHORT-LIVED BUT COULD CAUSE INTENSE HEAVY RAINFALL IN LOCALIZED
AREAS WITHIN A SHORT PERIOD OF TIME. A FEW OF THESE STORMS MAY
SURVIVE PAST SUNSET BUT OTHERWISE ARE EXPECTED TO DIMINISH AFTER
DARK. A VORT MAX AXIS WILL LIE NW TO SE ACROSS OUR AREA AND HELP
WITH STORM DEVELOPMENT AS WELL.
DISCREPANCY OVER THE WEEKEND ON THE AMOUNT OF MOISTURE WHICH WILL
REMAIN AVAILABLE BUT OVERALL TRENDS ARE SHOWING A SIMILAR
PATTERN.
SUNDAY IS EXPECTED TO BE SLIGHTLY DRIER UP ALONG THE WYOMING
BORDER WITH OUR CWA DUE TO DRY AIR ADVECTION KICKING INTO THE
REGION FROM THE NORTHWEST AND MINIMAL FORCING ALOFT...THEREFORE POPS
ARE AMPLIFIED TO THE SOUTHERN HALF OF OUR AREA. THIS IS NOT
EXPECTED TO LAST LONG AND WILL LIKELY KEEP A SECTION OF THE
NORTHERN REGION RAIN-FREE ON SUNDAY. ELSEWHERE...ESPECIALLY DOWN
IN THE SAN JUANS...ABAJOS...AND LA SALS...THE ATMOSPHERE WILL
REMAIN JUICY AND ALLOW FOR STRONG DIURNAL TSTORMS IN THE AFTERNOON.
MONDAY THROUGH WEDNESDAY...UPPER LEVEL HIGH PRESSURE STAYS POSITIONED
OVER COLORADO THROUGHOUT THE PERIOD. MONSOONAL MOISTURE CONTINUES
TO STREAM AROUND THE WRN PERIPHERY OF THE HIGH ALLOWING FOR DAILY
STORM INITIATION. SHORTWAVE ON TUESDAY SLICING THROUGH THE CENTER
OF THE HIGH PRESSURE WILL ALLOW FOR ENHANCED ACTIVITY ASSUMING
SKIES REMAIN FAIRLY CLEAR DURING THE FIRST HALF OF THE DAY.
THURSDAY COULD GET INTERESTING...BUT THIS FAR OUT THERE IS VERY
LOW CONFIDENCE IN THE LONG TERM MODELS...ESPECIALLY WITH TWO VERY
DIFFERENT SOLUTIONS. THE GFS IS PROGGING A STRONG PACIFIC LOW TO
DROP DOWN INTO THE INTERMOUNTAIN WEST THURSDAY SWIPING WITHIN NEAR
REACH OF THE REGION...FILTERING UNSEASONALLY COOL AIR INTO NORTHERN
BREACHES OF THE CWA. THE EURO KEEPS THIS FEATURE ALONG THE
NORTHERN ROCKIES WITHOUT MUCH INTERACTION WITH COLORADO AND UTAH.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 242 PM MDT THU AUG 29 2013
EXPECT THUNDERSTORMS IN VICINITY OF MOUNTAIN AIRPORTS WITH SOME
LOCALIZED AREAS OF HEAVY RAIN REDUCING VISIBILITY AND CEILINGS TO
IFR/MVFR AT TIMES. GUSTY ERRATIC WINDS CAN BE EXPECTED IN VICINITY
OF ANY STORMS. ACTIVITY IS EXPECTED TO WIND DOWN BY SUNSET OR
SHORTLY THEREAFTER WITH CLEARING SKIES OVERNIGHT. STORMS WILL
DEVELOP OVER THE HIGHER TERRAIN BY 18Z FRIDAY WITH SOME INCREASE
IN COVERAGE AS COMPARED TO TODAY. SOME STORMS MAY IMPACT VALLEY
AIRPORTS FRIDAY AFTERNOON INTO THE EVENING AS STORMS DRIFT OFF
HIGHER TERRAIN. VFR CONDITIONS WILL BE SEEN AT MOST TAF SITES
EXCEPT ASE...MTJ...EGE...AND ANY MOUNTAIN SITES THAT MAY SEE BRIEF
IFR/MVFR IN LOCALLY HEAVY RAIN.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...MDA
LONG TERM...JAM
AVIATION...MDA
AREA FORECAST DISCUSSION
NWS MIAMI FL
308 PM EDT THU AUG 29 2013
.SYNOPSIS...
A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST
THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA
WEAKENS THROUGH THE PERIOD.
&&
.SHORT TERM...TRHOUGH SATURDAY NIGHT.
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS
FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY
OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE
COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR
LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES
HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE.
NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE
WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION.
FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF
SHOWERS AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS
STILL AN OFF CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING
GUSTY WINDS AND LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND
LOCAL HIGH RES MODELS.
FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS
WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY
RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST
SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT
LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE
THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE
DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED
SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE
ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST
FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES
REMAIN DOMINANT.
.LONG TERM...SUNDAY THROUGH NEXT THURSDAY
WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH
RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE
AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF
DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE
PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND
NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...
THE EAST COAST SEA BREEZE HAS ALREADY PENETRATED WELL INLAND OF THE
EAST COAST TAF SITES THIS AFTERNOON...WHICH HAS PROVIDED MOSTLY
SUNNY CONDITIONS WITH LIGHT ONSHORE FLOW. THE COMBINATION OF THE
UPPER LOW CENTERED OVERHEAD AND LOW-LEVEL CONVERGENCE SETTING UP
INLAND HAS ALREADY BEGUN TO INITIATE A FEW SHOWERS AND
STORMS...MAINLY OVER THE LAKE AND GLADES COUNTY AREAS. THE LATEST
HRRR RUN CONTINUES TO INDICATE MOSTLY ISOLATED ACTIVITY ACROSS THE
INTERIOR THROUGH THE REMAINDER OF THE AFTERNOON/EVENING PERIODS.
HOWEVER...THE WRF SOLUTIONS STILL HINT AS SOME EAST COAST ACTIVITY
SETTING UP TOWARD PBI THROUGH THE EARLY EVENING PERIOD. DUE TO THIS
UNCERTAINTY...WILL INCLUDE VCTS IN THE PBI TAF THROUGH THE LATE
AFTERNOON/EARLY EVENING PERIODS AND UPDATE AS CONDITIONS EVOLVE.
OTHERWISE...VFR CONDITIONS ARE TO PREVAIL THROUGH THE REMAINDER OF
THE PERIOD. WINDS OVERNIGHT ARE FORECAST TO BECOME CALM OR LIGHT
OFFSHORE ASSOCIATED WITH A LAND BREEZE...THEN ONSHORE THROUGH THE
LATE MORNING/EARLY AFTERNOON HOURS FRIDAY. SLIGHT CHANCE FOR A FEW
MORNING SHOWERS SPREADING ASHORE ALONG THE EAST COAST
...HOWEVER...CONFIDENCE REMAINS TOO LOW TO INSERT IN THIS PACKAGE.
&&
.MARINE...
WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE
AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN
BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT
FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND
GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 75 90 / 20 30 20 30
FORT LAUDERDALE 78 91 78 90 / 20 30 20 30
MIAMI 78 92 77 90 / 20 30 20 30
NAPLES 75 91 74 90 / 20 30 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
530 PM CDT THU AUG 29 2013
.DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* HIGHER END MVFR VSBY POSSIBLE LATER EVENING AND OVERNIGHT INTO
EARLY FRI MORNING.
* CHANCE OF SHRA/TSRA LATER FRI AFTERNOON INTO EARLY EVENING.
* COLD FRONT DROPPING SE TO ACROSS N CENTRAL AND FAR NE IL BY
31.00Z.
TRS
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN ALL OPERATIONALLY SIGNIFICANT ELEMENTS
THROUGH THE NIGHT AND INTO FRI AFTERNOON.
* MEDIUM CONFIDENCE IN SCT TSRA MOVING INTO CHI AREA LATER
AFTERNOON AND EARLY EVENING.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
310 PM CDT THU AUG 29 2013
.DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICIES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICROBURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIRMASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* EAST WINDS JUST UNDER 10 KT THROUGH EARLY EVENING.
* MVFR VSBY POSSIBLE TONIGHT INTO EARLY FRIDAY.
* SOUTH-SOUTHWEST WINDS OF 200-230 DEG DEVELOP MID-LATE FRIDAY
MORNING WITH GUSTS TO AROUND 20 KT POSSIBLE.
* SHRA/TSRA POSSIBLE LATE AFTERNOON THROUGH EARLY EVE FRIDAY.
RC
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN EAST WINDS REMAINING PRIMARILY BELOW 10 KT
THROUGH EARLY THIS EVENING.
* MEDIUM CONFIDENCE THAT VSBY WILL REMAIN VFR OVERNIGHT THROUGH
EARLY FRIDAY.
* MEDIUM-HIGH CONFIDENCE IN WIND SPEED AND DIRECTION MID-LATE
FRIDAY MORNING THROUGH FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE THAT BEST POTENTIAL FOR SHRA/TSRA IS AT OR A
BIT AFTER 00Z FRIDAY EVENING.
RC
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
306 PM CDT THU AUG 29 2013
.DISCUSSION...
324 AM CDT
THE FORECAST CHALLENGES INCLUDE FOG IN THE NEAR TERM...THEN
INCREASING TEMPS AND THUNDERSTORM CHANCES FRIDAY...FOLLOWED BY A
COOL DOWN AND RETURN TO MORE SEASONABLE CONDITIONS TOWARD END OF THE
HOLIDAY WEEKEND.
GOES IMAGERY THIS MORNING SHOWS EXPANDING AREA OF STRATUS ACROSS
MUCH OF THE FORECAST AREA WITH SURFACE OBS AND WEBCAMS SHOWING A
SMATTERING OF DENSE FOG HERE AND THERE. ALL INDICATIONS ARE THAT THE
STRATUS IS THIN AND SHOULD BURN OFF QUICKLY THIS MORNING EXPECT NEAR
THE LAKE FRONT WHERE MARINE STRATUS AND POSSIBLY EVEN SOME FOG COULD
HOLD ON INTO THE AFTERNOON. ANOTHER COMPARATIVELY COOL DAY NEAR THE
LAKE WITH 70S RANGING QUICKLY UPWARD TO 80S INLAND JUST A FEW MILES
WITH UPPER 80S TO NEAR 90 EXPECTED SOUTHERN AND WESTERN PORTIONS OF
THE CWA.
SURFACE BOUNDARY STALLED OUT FROM SOUTHERN MINNESOTA TO CENTRAL
ILLINOIS WILL DISSIPATE THIS AFTERNOON INTO TONIGHT AS BROAD
SOUTHERLY FLOW DEVELOPS WITH SFC LOW TRACKING EAST INTO THE UPPER
GREAT LAKES FRIDAY MORNING. TRAILING COLD FRONT ALONG WITH GLANCING
BLOW FROM THE ASSOCIATED SHORTWAVE PASSING TO OUR NORTHEAST COULD
RESULT IN CONVECTION DEVELOPING FRIDAY AFTERNOON OVER SOUTHERN WI OR
POSSIBLY FAR NORTHERN ILLINOIS. HOT AND HUMID CONDITIONS WILL RESULT
IN MODERATE TO STRONG INSTABILITY ACROSS THE AREA THOUGH CONFIDENCE
IS LOW IN THE MAGNITUDE OF THE DEEP LAYER SHEAR. DEPENDING ON THE
TIMING AND TRACK OF THE VORT AND ASSOCIATED STRONGER MID LEVEL FLOW
SHEAR COULD BE WEAK TO POSSIBLY ON THE HIGHER END OF MODERATE. GIVEN
THE UNCERTAINTIES ABOUT POSSIBLE CONVECTIVE INITIATION AND MAGNITUDE
OF SHEAR IF STORMS DO FORM...CONFIDENCE IN SEVERE THREAT ISN`T HIGH
BUT WORTH KEEPING AN EYE ON SINCE NORTHWEST FLOWS CAN BE FULL OF
SURPRISES. MODELS ALL AGREE IN A RESURGENCE OF THE MORE INTENSE HEAT
AND HUMIDITY WITH HIGHS IN THE LOW TO MID 90S AND HEAT INDICES
POTENTIALLY GETTING UP CLOSE TO OR PERHAPS A BIT OVER 100 FRIDAY
AFTERNOON.
WEAK COLD FRONT LOOKS TO PASS THROUGH THE AREA FRIDAY NIGHT
RESULTING IN A WIND SHIFT TO THE NORTH AND SLIGHTLY COOLER AIR
ARRIVING SATURDAY...EXCEPT NEAR THE LAKE WHERE THE COOL DOWN WILL BE
MORE PRONOUNCED WITH THE FLOW OFF THE LAKE.
MUCH STRONGER SHORTWAVE WILL CREST THE TOP OF THE SLOWLY
RETROGRADING CENTRAL CONUS RIDGE SATURDAY BEFORE DIGGING SOUTHEAST
INTO THE GREAT LAKES REGION SUNDAY. STRONGER COLD FRONT WITH A MORE
ROBUST PUSH OF COOLER AND LESS HUMID AIR WILL MOVE THROUGH LATER
SUNDAY. ITS QUESTIONABLE HOW MUCH MOISTURE/INSTABILITY WILL BE
AROUND FOR CONVECTION WITH THIS SECOND FRONT IN THE WAKE OF THE
FIRST FROPA. HAVE MAINTAINED JUST CHANCE POPS FOR NOW WITH SOME
GUIDANCE STILL SUGGESTING A DRY SECONDARY FROPA AND GIVEN THE TRENDS
THIS SUMMER...DRIER IS USUALLY THE WAY TO GO.
DRY NORTHWEST FLOW THEN FORECAST TO SET UP OVER THE AREA THROUGH
MUCH OF NEXT WEEK. INITIAL PUSH OF COOLER AIR MONDAY INTO TUESDAY
WILL BE REPLACED WITH QUICK WARM UP MIDWEEK FOLLOWED BY ANOTHER
NORTHWEST FLOW COLD FRONT AND PUSH OF COOLER AIR. ALL IN ALL LOOKS
LIKE PRETTY TYPICAL EARLY METEOROLOGICAL FALL TYPE WEATHER.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* EAST WINDS JUST UNDER 10 KT THROUGH EARLY EVENING.
* MVFR VSBY POSSIBLE TONIGHT INTO EARLY FRIDAY.
* SOUTH-SOUTHWEST WINDS OF 200-230 DEG DEVELOP MID-LATE FRIDAY
MORNING WITH GUSTS TO AROUND 20 KT POSSIBLE.
* SHRA/TSRA POSSIBLE LATE AFTERNOON THROUGH EARLY EVE FRIDAY.
RC
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN EAST WINDS REMAINING PRIMARILY BELOW 10 KT
THROUGH EARLY THIS EVENING.
* MEDIUM CONFIDENCE THAT VSBY WILL REMAIN VFR OVERNIGHT THROUGH
EARLY FRIDAY.
* MEDIUM-HIGH CONFIDENCE IN WIND SPEED AND DIRECTION MID-LATE
FRIDAY MORNING THROUGH FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE THAT BEST POTENTIAL FOR SHRA/TSRA IS AT OR A
BIT AFTER 00Z FRIDAY EVENING.
RC
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
107 PM CDT THU AUG 29 2013
.DISCUSSION...
324 AM CDT
THE FORECAST CHALLENGES INCLUDE FOG IN THE NEAR TERM...THEN
INCREASING TEMPS AND THUNDERSTORM CHANCES FRIDAY...FOLLOWED BY A
COOL DOWN AND RETURN TO MORE SEASONABLE CONDITIONS TOWARD END OF THE
HOLIDAY WEEKEND.
GOES IMAGERY THIS MORNING SHOWS EXPANDING AREA OF STRATUS ACROSS
MUCH OF THE FORECAST AREA WITH SURFACE OBS AND WEBCAMS SHOWING A
SMATTERING OF DENSE FOG HERE AND THERE. ALL INDICATIONS ARE THAT THE
STRATUS IS THIN AND SHOULD BURN OFF QUICKLY THIS MORNING EXPECT NEAR
THE LAKE FRONT WHERE MARINE STRATUS AND POSSIBLY EVEN SOME FOG COULD
HOLD ON INTO THE AFTERNOON. ANOTHER COMPARATIVELY COOL DAY NEAR THE
LAKE WITH 70S RANGING QUICKLY UPWARD TO 80S INLAND JUST A FEW MILES
WITH UPPER 80S TO NEAR 90 EXPECTED SOUTHERN AND WESTERN PORTIONS OF
THE CWA.
SURFACE BOUNDARY STALLED OUT FROM SOUTHERN MINNESOTA TO CENTRAL
ILLINOIS WILL DISSIPATE THIS AFTERNOON INTO TONIGHT AS BROAD
SOUTHERLY FLOW DEVELOPS WITH SFC LOW TRACKING EAST INTO THE UPPER
GREAT LAKES FRIDAY MORNING. TRAILING COLD FRONT ALONG WITH GLANCING
BLOW FROM THE ASSOCIATED SHORTWAVE PASSING TO OUR NORTHEAST COULD
RESULT IN CONVECTION DEVELOPING FRIDAY AFTERNOON OVER SOUTHERN WI OR
POSSIBLY FAR NORTHERN ILLINOIS. HOT AND HUMID CONDITIONS WILL RESULT
IN MODERATE TO STRONG INSTABILITY ACROSS THE AREA THOUGH CONFIDENCE
IS LOW IN THE MAGNITUDE OF THE DEEP LAYER SHEAR. DEPENDING ON THE
TIMING AND TRACK OF THE VORT AND ASSOCIATED STRONGER MID LEVEL FLOW
SHEAR COULD BE WEAK TO POSSIBLY ON THE HIGHER END OF MODERATE. GIVEN
THE UNCERTAINTIES ABOUT POSSIBLE CONVECTIVE INITIATION AND MAGNITUDE
OF SHEAR IF STORMS DO FORM...CONFIDENCE IN SEVERE THREAT ISN`T HIGH
BUT WORTH KEEPING AN EYE ON SINCE NORTHWEST FLOWS CAN BE FULL OF
SURPRISES. MODELS ALL AGREE IN A RESURGENCE OF THE MORE INTENSE HEAT
AND HUMIDITY WITH HIGHS IN THE LOW TO MID 90S AND HEAT INDICES
POTENTIALLY GETTING UP CLOSE TO OR PERHAPS A BIT OVER 100 FRIDAY
AFTERNOON.
WEAK COLD FRONT LOOKS TO PASS THROUGH THE AREA FRIDAY NIGHT
RESULTING IN A WIND SHIFT TO THE NORTH AND SLIGHTLY COOLER AIR
ARRIVING SATURDAY...EXCEPT NEAR THE LAKE WHERE THE COOL DOWN WILL BE
MORE PRONOUNCED WITH THE FLOW OFF THE LAKE.
MUCH STRONGER SHORTWAVE WILL CREST THE TOP OF THE SLOWLY
RETROGRADING CENTRAL CONUS RIDGE SATURDAY BEFORE DIGGING SOUTHEAST
INTO THE GREAT LAKES REGION SUNDAY. STRONGER COLD FRONT WITH A MORE
ROBUST PUSH OF COOLER AND LESS HUMID AIR WILL MOVE THROUGH LATER
SUNDAY. ITS QUESTIONABLE HOW MUCH MOISTURE/INSTABILITY WILL BE
AROUND FOR CONVECTION WITH THIS SECOND FRONT IN THE WAKE OF THE
FIRST FROPA. HAVE MAINTAINED JUST CHANCE POPS FOR NOW WITH SOME
GUIDANCE STILL SUGGESTING A DRY SECONDARY FROPA AND GIVEN THE TRENDS
THIS SUMMER...DRIER IS USUALLY THE WAY TO GO.
DRY NORTHWEST FLOW THEN FORECAST TO SET UP OVER THE AREA THROUGH
MUCH OF NEXT WEEK. INITIAL PUSH OF COOLER AIR MONDAY INTO TUESDAY
WILL BE REPLACED WITH QUICK WARM UP MIDWEEK FOLLOWED BY ANOTHER
NORTHWEST FLOW COLD FRONT AND PUSH OF COOLER AIR. ALL IN ALL LOOKS
LIKE PRETTY TYPICAL EARLY METEOROLOGICAL FALL TYPE WEATHER.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* EAST WINDS JUST UNDER 10 KT THROUGH EARLY EVENING.
* MVFR VSBY POSSIBLE TONIGHT INTO EARLY FRIDAY.
* SOUTH-SOUTHWEST WINDS OF 200-230 DEG DEVELOP MID-LATE FRIDAY
MORNING WITH GUSTS TO AROUND 20 KT POSSIBLE.
* SHRA/TSRA POSSIBLE LATE AFTERNOON THROUGH EARLY EVE FRIDAY.
RC
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN EAST WINDS REMAINING PRIMARILY BELOW 10 KT
THROUGH EARLY THIS EVENING.
* MEDIUM CONFIDENCE THAT VSBY WILL REMAIN VFR OVERNIGHT THROUGH
EARLY FRIDAY.
* MEDIUM-HIGH CONFIDENCE IN WIND SPEED AND DIRECTION MID-LATE
FRIDAY MORNING THROUGH FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE THAT BEST POTENTIAL FOR SHRA/TSRA IS AT OR A
BIT AFTER 00Z FRIDAY EVENING.
RC
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
310 AM CDT
HIGH PRESSURE IS OVER THE GREAT LAKES WITH LIGHT WINDS EXPECTED
TODAY. OVER THE SOUTHERN HALF OF THE LAKE WINDS WILL TURN ONSHORE
RESULTING IN VARIABLE WINDS. LOW PRESSURE CURRENTLY OVER THE
DAKOTAS SHIFTS EAST AND WINDS BECOME SOUTH AHEAD OF IT TONIGHT. THE
LOW PASSES OVER THE LAKE FRIDAY WITH NORTH WINDS EXPECTED BEHIND THE
LOW FRIDAY NIGHT. A BRIEF RIDGE OF HIGH PRESSURE MOVES OVER THE
LAKE SATURDAY BEFORE A MUCH MORE SUBSTANTIAL LOW PASSES NORTH OF THE
LAKE SUNDAY. GUIDANCE STILL DIFFERS ON THE TRACK OF THE LOW BUT
WENT WITH THE MORE CONSISTENT ECMWF MODEL THAT CONTINUES TO INDICATE
THE LOW WILL PASS NORTH OF THE LAKE. WINDS TURN NORTH BEHIND THE
LOWS COLD FRONT SUNDAY NIGHT WITH WINDS AT LEAST 15 TO 25 KT
EXPECTED SUNDAY NIGHT AND MONDAY. WILL MONITOR WINDS AND WAVES OVER
INDIANA NEXT MONDAY BECAUSE A SMALL CRAFT ADVISORY AND RIP CURRENT
STATEMENT MAY BOTH BE NEEDED FOR THE INDIANA NEARSHORE WATERS
MONDAY AND MONDAY NIGHT. HIGH PRESSURE MOVES IN MONDAY NIGHT
ALLOWING WINDS TO DIMINISH IN SPEED.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1250 PM CDT THU AUG 29 2013
.UPDATE...
ISSUED AT 628 AM CDT THU AUG 29 2013
SURFACE OBSERVATIONS INDICATED LOCALLY DENSE FOG HAS FORMED JUST
ALONG THE BOUNDARY IN SE IA. FOG AND LOW STRATUS IS ALSO SHOWING UP
ALONG WHAT NOW LOOKS TO BE A REINFORCING BACKDOOR COOL FRONT THAT
CONTINUES TO ADVANCE WESTWARD ACROSS IL...REACHING FROM ABOUT
STOCKTON TO KEWANEE. HAVE UPDATED THE FORECAST TO HIT FOG WORDING
A LITTLE HEAVIER AND FOR MORE CLOUD COVER EARLY THIS MORNING. MOST
RECENT RAP MODEL 925 MB RH FIELDS INDICATE THE ADVANCING STRATUS
AND SEPARATE AREA OF STRATUS DEVELOPING OVER EAST CENTRAL IA MAY
MERGE INTO A DECK IN THE LOW LEVEL CONVERGENCE AXIS THAT COULD
HOLD FOR MUCH OF THE MORNING. WILL CONTINUE TO WATCH THESE TRENDS
CLOSELY AS ANY DELAYED CLEARING COULD IMPACT TEMPERATURES.
&&
.SYNOPSIS...
ISSUED AT 343 AM CDT THU AUG 29 2013
AT 07Z THE SURFACE BOUNDARY WAS NEARLY STATIONARY FROM N CENTRAL
IA...SOUTHEAST TO SOUTH CENTRAL IL...JUST SOUTH OF A LINE FROM OTM
TO SOUTHEAST IA TO MQB IN W CENTRAL IL. LIGHT EASTERLY WINDS AND
LOW LEVEL MOISTURE POOLING NORTHEAST OF THIS BOUNDARY WAS KEEPING
BOTH TEMPERATURES AND DEWPOINTS IN THE 70S OVER ALL BUT THE FAR
SOUTHWEST AND NORTHEASTERN PORTIONS OF THE FORECAST AREA. THIS
MOISTURE CONVERGENCE WAS RESULTING IN AREAS OF DEVELOPING LOW
CLOUDS AND FOG. SO FAR THIS HAS BEEN CONFINED TO CLOSEST TO THE
BOUNDARY IN SE IA AND W CENTRAL IL. SATELLITE FOG CHANNEL IMAGERY
SHOWED AN AREA OF LOW CLOUDS EXPANDING EAST OUT OF NE IL...IN THE
LIGHT EASTERLY FLOW AROUND HIGH PRESSURE OVER WI AND LOWER MI. 00Z
UPPER AIR ANALYSIS SHOWED THE UPPER RIDGE HOLDING STRONG FROM AR
AND MO N-NE INTO THE NORTHERN PLAINS. THE HEAT DOME REMAINED IN
PLACE OVER THE PLAINS AND ROCKIES WITH A THERMAL RIDGE OF 850 MB
TEMPERATURES IN THE LOWER 20S REACHING FROM NEB AND SD E-SE ACROSS
IA INTO THE OHIO VALLEY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT THU AUG 29 2013
CHALLENGES INCLUDE FOG TRENDS EARLY THIS MORNING...THEN THE
MAGNITUDE OF HEAT AND HUMIDITY TODAY AND TONIGHT AS THE ON-GOING
LATE AUGUST HEAT WAVE CONTINUES.
EARLY THIS MORNING...STRATUS DECK OVER NE IL WILL LIKELY CONTINUE
WESTWARD...BUT AT THE CURRENT RATE...DO NOT EXPECT IT TO REACH THE
MS RIVER UNTIL AFTER SUNRISE...AND CONFIDENCE NOT HIGH THAT IT WILL
HOLD TOGETHER OR CONTINUE AT THE SAME PACE. HAVE ALREADY UPDATED TO
ADD AREAS OF EARLY MORNING FOG FOR MUCH OF THE FORECAST AREA. BASED
ON TRENDS THE PAST FEW DAYS WITH THIS BOUNDARY...WILL EXPECT ANY FOG
TO BURN OFF BY MID MORNING.
THE STATIONARY FRONT IS STILL PROGGED TO SLOWLY DISSIPATE AS HIGH
PRESSURE BUILDS SOUTHEAST INTO THE GREAT LAKES AND WINDS BECOME
LIGHT SE TO SOUTH. SOUTHWEST OF THIS CONVERGENCE ZONE...IT WILL BE
ANOTHER DAY OF DEEP MIXING AND NEAR RECORD HEAT WITH THE AIRMASS
SUPPORTING HIGHS WELL INTO THE MID AND POSSIBLY UPPER 90S AND HEAT
INDEX READINGS BACK ABOVE 100. ALONG AND JUST NORTHEAST OF THE
BOUNDARY...DEWPOINTS LINGERING IN THE 70S WILL RESULT IN HEAT
INDEX READINGS ABOVE 100 AS WELL...DESPITE SLIGHTLY COOLER HIGHS
AROUND 90 TO THE LOWER 90S. FAR EAST CENTRAL IA AND NW IL...IN THE
MODIFIED DRIER GREAT LAKES AIRMASS AND LIGHT EASTERLY WINDS...
HIGHS SHOULD BE LIMITED TO THE MID TO UPPER 80S WITH HEAT INDEX
VALUES FROM THE UPPER 80S TO LOWER 90S. THIS SUPPORTS THE CURRENT
HEAT ADVISORY AREA AND WILL BE KEEPING IT INTACT TODAY AND HAVE
EXPANDED INTO FRIDAY. CANNOT RULE OUT AN ISOLATED BRIEF SHOWER TO
BREAK THROUGH THE CAP ALONG THE BOUNDARY AS OCCURRED LATE
YESTERDAY...BUT DOES NOT LOOK WORTHY OF MENTION BEYOND A 10
PERCENT POP.
TONIGHT...DEWPOINTS WILL RECOVER BACK INTO THE UPPER 60S TO LOWER
70S OVER MOST OF THE AREA...SUPPORTING LOWS IN A RANGE FROM THE
UPPER 60S NORTHEAST TO MID 70S IN THE FAR SOUTH. ANY NOCTURNAL
CONVECTION IN THE NORTHERN PLAINS OR UPPER MS VALLEY SHOULD REMAIN
NORTH OF THE AREA AND HAVE A DRY FORECAST.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 343 AM CDT THU AUG 29 2013
FORECAST FOCUS ON A SCORCHER ON FRIDAY THEN STRONG COLD FRONT
ARRIVES ON SUNDAY ENDING THE HEAT WAVE.
FRIDAY THROUGH SATURDAY...COMPRESSIONAL HEATING AHEAD OF A WEAK COLD
FRONT WILL PUSH TEMPERATURES TO NEAR RECORD LEVELS AT SOME LOCATIONS
ON FRIDAY. 850 MB TEMPERATURES ARE PROGGED TO +22 TO 24C AND WITH A
CAPPED ATMOSPHERE SURFACE TEMPERATURES SHOULD SOAR INTO THE MID TO
UPPER 90S AT MANY LOCATIONS. COMBINED WITH DEWPOINTS AT LEAST IN THE
LOWER 70S THIS WILL CREATE HEAT INDEX VALUES OF 100 TO 107. THIS IS
THE REASON FOR EXTENDING THE HEAT ADVISORY TO 7 PM ON FRIDAY. HAVE
LEFT OUT OUR NORTHEAST COUNTIES FOR NOW AS SOME DEBATE ON THE
POTENTIAL FOR DEBRIS CLOUDS FROM A POSSIBLE MCS PUSHING ACROSS THE
GREAT LAKES. IF A FULLY SUNNY DAY IS EVIDENT THEN THE ADVISORY WILL
NEED TO BE ISSUED FOR OUR NORTHEAST CWA.
A SIGNIFICANT SHORT WAVE WILL BE MOVING ACROSS THE MIDWEST WHICH
WILL SEND A WEAK COLD FRONT INTO THE DVN CWA BY FRIDAY EVENING. THE
CAP SHOULD WEAKEN AS CONVECTIVE TEMPERATURES ARE REACHED BUT MODELS
DIFFER ON COVERAGE OF ANY CONVECTION. THE GFS IS MUCH MORE
AGGRESSIVE WITH INDICATING WIDESPREAD THUNDERSTORMS FRIDAY NIGHT BUT
THE ECMWF HINTS AT ONLY ISOLATED OR WIDELY SCATTERED COVERAGE. ANY
STORMS THAT DO FORM IN THE VERY UNSTABLE ATMOSPHERE MAY BE CAPABLE
OF ISOLATED DAMAGING WIND. FOR NOW WILL GO WITH A 30 PERCENT POP.
SPC HAS THE ENTIRE CWA IN A SEE TEXT WITH A 5% PROBABILITY OF SEVERE.
THE FRONT WILL STALL IN THE AREA ON SATURDAY KEEPING TEMPERATURES A
BIT LOWER WITH HIGHS RANGING FROM THE UPPER 80S NORTH TO MID 90S
SOUTH. THE HEAT ADVISORY MAY NEED TO BE EXTENDED IN OUR SOUTH ON
SATURDAY.
SUNDAY THROUGH NEXT WEEK...A STRONG COLD FRONT WILL SWEEP ACROSS THE
CWA ON SUNDAY BRINGING WITH IT A 30-40% CHANCE FOR THUNDERSTORMS.
THIS OCCURRING AS A DEEPENING TROUGH DIGS SOUTHEAST INTO THE MIDWEST
AND GREAT LAKES. THE TIMING WILL BE CRUCIAL TO COVERAGE AND
INTENSITY OF THE STORMS. IF THE FRONT CAN ARRIVE DURING THE
AFTERNOON THEN THE SEVERE WEATHER POTENTIAL WILL INCREASE. WITH THE
PASSAGE OF THE FRONT MUCH COOLER AND LESS HUMID AIR WILL MAKE FOR A
VERY PLEASANT LABOR DAY AND ALSO ON TUESDAY. HIGHS WILL BE IN THE
70S TO LOWER 80S AND LOWS IN THE 50S EARLY IN THE WEEK.
TEMPERATURES SHOULD WARM BACK INTO THE 80S NEXT WEDNESDAY AHEAD OF
ANOTHER STRONG COLD FRONT WHICH WILL THEN USHER ANOTHER FALL-LIKE
AIRMASS INTO THE MIDWEST FOR LATE IN THE WEEK. HOWEVER...MUCH OF NEXT
WEEK LOOKS DRY.
HAASE
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1243 PM CDT THU AUG 29 2013
ASIDE FROM THE LAST OF A LINGERING STRATUS DECK AT 2400 FT AT/NEAR MLI
AND DBQ FOR THE FIRST HOUR/TWO OF PERIOD...VFR CONDITIONS WILL
PREVAIL THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING. AFTER
MIDNIGHT...EXPECT SOME MVFR VISIBILITIES /4-5SM/ IN FOG TO DEVELOP
AND LAST THROUGH 14Z. LIGHT SOUTH SOUTHWEST WINDS WILL BE COMMON
THROUGH THE PERIOD WITH SPEEDS UNDER 10 KTS.
&&
.CLIMATE...
ISSUED AT 343 AM CDT THU AUG 29 2013
RECORD HIGHS FOR AUGUST 29...
MOLINE.........97 IN 1984
CEDAR RAPIDS...97 IN 1925
DUBUQUE........99 IN 1984
BURLINGTON.....96 IN 1953
RECORD HIGHS FOR AUGUST 30...
MOLINE.........98 IN 1953 AND PREVIOUS YEARS
CEDAR RAPIDS...100 IN 1953
DUBUQUE........94 IN 1941 AND PREVIOUS YEARS
BURLINGTON.....102 IN 1947
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR BENTON-BUCHANAN-CEDAR-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR HANCOCK-HENDERSON-HENRY
IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR CLARK-SCOTLAND.
&&
$$
UPDATE...SHEETS
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...14
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS DULUTH MN
350 PM CDT THU AUG 29 2013
.SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
&&
.AVIATION...18Z TAF ISSUANCE...
LINE OF THUNDERSTORMS CURRENTLY MOVING TO THE EAST JUST NORTH OF
DLH WITH GUSTY WINDS...HEAVY LINE AND FREQUENT LIGHTNING. A BRIEF
BREAK IN THE CONVECTION IS EXPECTED EARLY THIS AFTERNOON BEFORE
ANOTHER ROUND DEVELOPS IN THE LATE AFTERNOON ACROSS N-CENTRAL MN
AND MOVES ACROSS THE NORTHLAND EARLY THIS EVENING. SOME OF THE
STORMS COULD BECOME STRONG TO SEVERE WITH VERY GUSTY WINDS AND
HAIL. A FEW OF THE STORMS COULD LINGER AROUND HYR UNTIL
06-08Z...OTHERWISE CONDITIONS CLEAR OUT FROM WEST TO EAST INTO
EARLY FRIDAY MORNING. WINDS WILL INCREASE FROM THE NNW DURING THE
MORNING FRIDAY...WITH MVFR CIGS.
&&
.POINT TEMPS/POPS...
DLH 64 80 58 79 / 80 30 0 20
INL 61 84 62 82 / 80 10 20 50
BRD 68 86 62 86 / 50 10 0 40
HYR 71 83 58 84 / 70 30 0 10
ASX 68 78 59 78 / 80 30 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...DAP
LONG TERM....TENTINGER
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
539 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTH THROUGH THE AREA
TONIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH
FRIDAY AND SATURDAY. THE HIGH WILL GRADUALLY SHIFT OFFSHORE WITH
ANOTHER COLD FRONT APPROACHING TUESDAY BEFORE MOVING OFFSHORE ON
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 535 PM THURSDAY...THE FRONT ON SATELLITE AND RADAR IMAGERY
IS MOVING SOUTHWEST ACROSS EASTERN NC EARLY THIS EVENING AND @ 530
PM WAS LOCATED ROUGHLY ALONG A GREENVILLE TO TO NEWPORT LINE.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WERE OCCURRING ALONG AND
IN VICINITY OF THE BOUNDARY. THE HRRR MODEL WAS IN SYNC WITH
CURRENT RADAR TRENDS AND INDICATES THAT SHOWER THREAT WILL ENDING
SHORTLY AFTER 00Z AIDED BY LOSS OF SURFACE HEATING AND THE FRONT
MOVING OUT OF THE AREA. MODERATE NORTHEAST SURGE FOLLOWS THE FRONT
BUT IS FORECAST TO SUBSIDE AFTER MIDNIGHT WITH THE POTENTIAL FOR
PATCHY FOG IN AREAS THAT DECOUPLE. A MORE LIKELY SCENARIO IS THE
DEVELOPMENT OF WIDESPREAD LOW STRATUS CLOUDS AFTER 06Z AS THE
BOUNDARY LAYER FLOW REMAINS WELL MIXED ABOVE A SHALLOW
NOCTURNAL/FRONTAL INVERSION. FORECAST LOW TEMPERATURES WILL RANGE
FROM THE MIDDLE 60S INLAND TO THE LOWER 70S BEACHES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
AS OF 245 PM THURSDAY...FRIDAY WILL BE CHARACTERIZED BY A SLIGHTLY
DRIER AIRMASS WITH WARM TEMPERATURES IN THE MIDDLE TO UPPER 80S
AWAY FROM THE IMMEDIATE COAST. DEWPOINTS WILL DROP INTO THE UPPER
60S WITH A LIGHT NORTHEAST WIND AS HIGH PRESSURE BUILDS SOUTH
ACROSS THE MID-ATLANTIC. MAY START THE DAY WITH SOME LOW STRATUS
BUT IT SHOULD DISSIPATE AS THE DRIER AIR STARTS TO MIX TO THE
SURFACE BY MID MORNING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE
ACROSS THE AREA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE
WILL TRANSITION OFF THE COAST SAT WHILE A BOUNDARY PUSHES BACK
NORTH OVER THE REGION BY LATE AFTERNOON AS A WEAK WARM FRONT.
LITTLE IF ANY PRECIP IS EXPECTED TO OCCUR AS BOUNDARY LAYER WILL
REMAIN DRY...THOUGH AN ISO SHOWER/STORM POSSIBLE INLAND WITH SEA
BREEZE PROPAGATION AND WILL MAINTAIN ISOLATED POPS SAT
AFTERNOON...WITH BEST CHANCES ACROSS SOUTHERN CWA. SW RETURN FLOW
INCREASES SUN BRINGING WARM/MOIST CONDITIONS BACK TO THE AREA WITH
FORECAST SOUNDINGS INDICATING PWATS NEAR 2 INCHES. WILL CONTINUE
LOW END CHANCE POPS INLAND AND SLIGHT E OF HWY 17.
BY MON AN UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA WILL DIG
SOUTH AND EAST INTO THE GREAT LAKES REGION. SHORT WAVE ENERGY IN
BROAD SW FLOW WILL MOVE ACROSS THE REGION BRINGING A BETTER CHANCE
FOR ORGANIZED CONVECTION IN TANDEM WITH PIEDMONT TROUGH AND SEA
BREEZE...AND HAVE MAINTAINED CHANCE POPS ACROSS THE REGION. FOR
TUES...THE UPPER TROUGH WILL MOVE EAST FROM THE GREAT LAKES INTO
THE NORTHEASTERN STATES...DRAGGING A COLD FRONT THROUGH EASTERN NC
LATE TUE INTO TUE NIGHT. WILL CONTINUE GOOD CHANCE POPS TUE
TAPERING OFF BEHIND THE FRONT TUE NIGHT INTO WED. TEMPS THROUGH
THE PERIOD WILL BE NEAR CLIMO...WITH HIGHS GENERALLY IN THE MID
80S TO AROUND 90 DEGREES. THE WARMEST DAYS OF THE PERIOD LOOK LIKE
SUN AND MON. SLIGHTLY COOLER AND DRIER AIRMASS EXPECTED BEHIND THE
FRONT FOR WED/THU...THOUGH NO SIG TEMP SWINGS EXPECTED.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 535 PM THURSDAY...SHOWER THREAT WILL ENDING AT THE TAF SITES
AROUND 00Z. MAIN CONCERN TONIGHT IS THE POTENTIAL FOR WIDESPREAD
IFR CONDITIONS. A MODERATE NORTHEAST SURGE IS OCCURRING BEHIND A
SOUTHWEST MOVING COLD FRONTAL BOUNDARY WHICH IS MOVING THROUGH THE
TAF SITES EARLY THIS EVENING. THIS SURGE IS EXPECTED TO SUBSIDE
AFTER 06Z AND ALONG WITH CLEARING BEHIND THE FRONT COULD LEAD TO
PATCHY FOG ESPECIALLY IN AREAS THAT RECEIVED RAINFALL AND WHERE
WINDS DECOUPLE. WHAT IS MORE LIKELY TO OCCUR IS THAT WIDESPREAD
STRATUS WILL DEVELOP AS THE BOUNDARY LAYER ABOVE THE SURFACE
REMAINS WELL MIXED OVERNIGHT. ALL OF THE AVIATION GUIDANCE FROM
BUFKIT TO THE UPS FOG TOOL TO THE MOS IS INDICATING IFR CEILINGS
AND/OR VISIBILITIES AFTER 06Z SO WILL CONTINUE TREND ESTABLISHED
IN PREVIOUS TAFS AND FORECAST IFR AROUND 08Z THROUGH 14Z FRIDAY.
VFR CONDITIONS THEN A FORECAST TO PREVAIL AFTER THE FOG/STRATUS
DISSIPATE AS HIGH PRESSURE AND DRIER AIR BUILD OVER THE REGION.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...PRED VFR CONDITIONS EXPECTED THROUGH THE
PERIOD. A COLD FRONT WILL APPROACH FROM THE WEST MONDAY
NIGHT...MOVING THROUGH EASTERN NC LATE TUE AND TUE NIGHT. SCT
MAINLY DIURNAL SHOWERS/TSTMS POSSIBLE SUN THROUGH TUE WITH PERIODS
OF SUB-VFR POSSIBLE. WITH CALM TO LIGHT WINDS OVERNIGHT AND MOIST
BL...COULD SEE PATCHY FOG/STRATUS EACH NIGHT AND EARLY MORNING.
&&
.MARINE...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 535 PM THURSDAY...COLD FRONT CONTINUES TO MOVE SOUTHWEST
THROUGH THE WATERS FOLLOWED BY A MODERATE NORTHEAST SURGE WITH
SUSTAINED WINDS TO 20 KT AND A FEW GUSTS TO 25 KT. THESE WINDS
WILL CONTINUE THROUGH THE EVENING THEN BEGIN TO SUBSIDE AFTER 06Z
AS THE GRADIENT RELAXES LATE. ON FRIDAY NORTHEAST WINDS AROUND 15
KT IN THE MORNING WILL SUBSIDE TO 10 KT LATE IN THE AFTERNOON. SEAS
WILL RANGE FROM 3 TO 5 FEET NORTH TO 2 TO 4 FEET SOUTH.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE OVER
THE WATERS THIS WEEKEND INTO EARLY NEXT WEEK. OVERALL EXPECT
PLEASANT BOATING CONDITIONS THIS WEEKEND WITH VEERING WINDS 5-15KT
AND SEAS 2-4FT. A COLD FRONT WILL APPROACH THE WATERS FROM THE
WEST MON NIGHT INTO TUE...MOVING THROUGH TUE NIGHT INTO EARLY WED
MORNING. A BRIEF PERIOD OF SCA CONDITIONS WILL BE POSSIBLE MONDAY
EVENING...MAINLY FOR THE CENTRAL WATERS...AS GRADIENT TIGHTENS
AHEAD OF APPROACHING FRONT. SWLY WINDS EXPECTED TO INCREASE TO
15-20KT WITH SEAS BUILDING TO 6FT ACROSS THE OUTER CENTRAL WATERS.
SW FLOW 10-20KT WILL CONTINUE INTO TUE WITH SEAS 5FT OR LESS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC/JME
NEAR TERM...CTC/JME
SHORT TERM...CTC
LONG TERM...CQD
AVIATION...JME/CQD/LEP
MARINE...CTC/JME/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
330 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE EASTERN CAROLINAS THIS EVENING
AS HIGH PRESSURE OVER THE MID-ATLANTIC STATES BUILDS IN. THE HIGH
WILL MOVE OFFSHORE SATURDAY ALLOWING A WARM FRONT TO RETURN
NORTHWARD SATURDAY AFTERNOON. HOT AND HUMID CONDITIONS ARE
EXPECTED NEXT WEEK...UNTIL A STRONGER COLD FRONT ARRIVES FROM THE
NORTH TUESDAY NIGHT OR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...COLD FRONT CONTINUES TO MAKE PROGRESS
SOUTHWARD AS IT EXTENDS WESTWARD FROM LOW PRESSURE CENTER
NORTHEAST OF CAPE HATTERAS. THE BEST CONVECTION AND LIGHTNING WITH
THIS SYSTEM REMAINS OUT OVER THE COASTAL WATERS EAST OF HATTERAS
CLOSE TO THE LOW AND WHERE BEST UPPER LEVEL SUPPORT EXISTS. AS
BOUNDARY SINKS SOUTH REACHING JUST NORTH OF LOCAL CWA...THE WINDS
WERE SHIFTING TO THE NORTH BEHIND IT AND A FEW SHOWERS WERE
STARTING TO POP UP JUST NORTH OF CWA AND STREAMING SOUTH. ALTHOUGH
THE WINDS WERE SHIFTING TO THE NORTH...THE DEWPOINT TEMPS WERE NOT
SHOWING MUCH OF A DROP WITH PLENTY OF MOISTURE AND CLOUDS WRAPPING
AROUND THE LOW WELL UP INTO THE MID ATLANTIC STATES THIS
AFTERNOON. EXPECT CLOUDS TO SPREAD SOUTH WITH INCREASING SHOWER
ACTIVITY AS FRONT DROPS THROUGH AREA THIS AFTERNOON INTO EARLY
THIS EVENING.
TEMPS IN THE MID TO UPPER 80S MOST PLACES BUT TAPERING OFF AS
CLOUDS SPREAD SOUTH. AREAS OF GREATER HEATING WILL AID IN
DESTABILIZING THE ATMOSPHERE MORE. LOOKING AT SOUNDING DATA AND
CONVECTIVE PARAMETERS...THE ML CAPE DOES INCREASE CLOSE TO 2000
J/KG WHILE DCAPES UP TO 1600 J/KG THIS AFTERNOON. THE OVERALL
PROFILE SHOWS FAIRLY DECENT DRY LAYER FROM THE SURFACE UP CLOSE TO
10 K FT. PCP WATER VALUES ACTUALLY DECREASE THROUGH THIS AFTERNOON
AS LAYER OF MOIST AIR BETWEEN 10 AND 20K FT GETS ERODED SOMEWHAT.
MID TO UPPER LEVELS REMAIN WARM WITH -5C TEMPS THIS AFTERNOON WITH
THE MID LEVEL LAPSE RATES REMAINING UNIMPRESSIVE AND MOISTURE
THROUGH THE COLUMN ACTUALLY DIMINISHES THROUGH THIS AFTERNOON.
ANOTHER FACTOR WILL BE THE ACTUAL FORCING MECHANISM TO INITIATE
ANY CONVECTION AS THE BEST MID TO UPPER LEVEL SUPPORT REMAINS
EAST OF MID TO UPPER TROUGH OVER THE ATLANTIC. A FEW MINOR
PERTURBATIONS IN THE MID TO UPPER LEVEL FLOW MAY ACT TO ENHANCE
SOME CONVECTIVE DEVELOPMENT...BUT OVERALL EXPECT BEST FORCING TO
COME FROM FRONT MOVING SOUTH AIDED BY CONVERGENCE ALONG SEA
BREEZE. THE SEA BREEZE SHOULD REMAINED PINNED CLOSER TO THE COAST
WITH A STRONGER W-SW FLOW. THE WESTERLY DOWNSLOPE COMPONENT TO THE
FLOW AHEAD OF THE FRONT WILL ALSO WORK AGAINST CONVECTIVE
DEVELOPMENT...BUT EXPECT MORE ISOLATED SHOWERS INLAND WITH BETTER
CONVECTIVE DEVELOPMENT AS FRONT INTERACTS WITH SEA BREEZE CLOSER
TO THE COAST...ESPECIALLY FROM CAPE FEAR SOUTH INTO NORTHEAST
SOUTH CAROLINA. MAIN ACTIVITY STILL FORECAST TO OCCUR AS FRONT
DROPS SOUTH AND INTERACTS WITH SEA BREEZE BETWEEN 2 PM TO 5 PM
OVER CAPE FEAR AND CONTINUING SOUTH MOVING OVER SOUTH CAROLINA
THROUGH THE LATE AFTERNOON INTO EARLY THIS EVENING. ALTHOUGH NOT
EXPECTING VERY WIDESPREAD OR DEEP CONVECTION...A FEW STORMS COULD
POTENTIALLY PRODUCE SOME VERY GUSTY WINDS INDICATIVE OF INVERTED-V
SOUNDING PROFILE AND DCAPES OF 1600 J/KG.
AS THE FRONT MOVES TO THE SOUTH OF THE SOUTH SANTEE RIVER DURING
THE LATE EVENING HOURS AND WINDS SHIFT AROUND TO THE NORTH TO
NORTHEAST...MORE STABLE AIR WILL ARRIVE FROM THE NORTH. THE RELATIVELY
COOLER AIR MAKING ITS WAY IN BEHIND THE FRONT COMBINING WITH
LINGERING MOISTURE AND EASTERLY COMPONENT TO THE FLOW COULD
PRODUCE SOME STRATUS AND FOG OVERNIGHT. LOWS TONIGHT WILL BE A
LITTLE TRICKY AS DEWPOINT TEMPS DROP TO THE MID 60S BUT CLOUDS AND
MOISTURE MAY LINGER IN LOW LEVELS. WILL HOLD MOST LOW TEMPS CLOSER
TO 70 WITH SOME 60S OVER NORTHERN TIER COUNTIES AS COOLER AND
DRIER AIR ADVECTS IN FROM THE NORTH.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...THE UPPER RIDGE ACROSS THE PLAINS STATES
WILL WEAKEN AND RETROGRADE INTO THE DESERT SOUTHWEST LATE THIS
WEEK AS A SERIES OF SHORTWAVE TROUGHS ERODE HEIGHTS ACROSS THE
NORTHERN PLAINS...GREAT LAKES AND NORTHEASTERN STATES. AT THE
SURFACE THE COLD FRONT SHOULD MAKE IT DOWN TO ALMOST THE FLORIDA-
GEORGIA STATE LINE FRIDAY AFTERNOON. SURFACE HIGH PRESSURE OFF
THE MD/DE COAST WILL MAINTAIN A NE LOW-LEVEL FLOW ACROSS THE
EASTERN CAROLINAS. ALTHOUGH THIS IS NOT A COOL DRY AIRMASS...
THETA-E VALUES SHOULD FALL JUST ENOUGH TO MAKE DAYTIME CONVECTION
ONLY ISOLATED AT BEST ACROSS EASTERN SOUTH CAROLINA FRIDAY.
AS THE HIGH MOVES FARTHER OFF THE MID-ATLANTIC COAST SATURDAY THE
FRONT WILL BE DRAWN NORTHWARD...LIKELY MOVING BACK ACROSS THE AREA
SATURDAY AFTERNOON. ISOLATED SHOWERS ARE AGAIN POSSIBLE BUT
COVERAGE SHOULD BE LIMITED BY VERY DRY AIR ALOFT WITH MID-LEVEL
RIDGING PERSISTING. THE APPROACH OF THE TAIL END OF AN UPPER
DISTURBANCE SATURDAY NIGHT COULD LEAD TO AN INCREASE IN SHOWER
CHANCES...ESPECIALLY OFFSHORE AND PERHAPS NEAR THE COAST.
GFS AND NAM MOS ARE IN GOOD AGREEMENT WITH HIGH AND LOW
TEMPERATURES THROUGH THE NEXT SEVERAL PERIODS...AND BOTH AGREE
WITH FORECAST SOUNDING-DERIVED TECHNIQUES. UNLIKE YESTERDAY EVEN
THE EXPERIMENTAL ECMWF MOS IS IN THE BALLPARK FRIDAY THROUGH
SATURDAY NIGHT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 PM THURSDAY...WITH AN EASTWARD PROPAGATING UPPER LEVEL
TROUGH APPROACHING THE AREA JUST AHEAD OF THE UPCOMING COLD FRONTAL
PASSAGE...PRECIPITABLE WATER VALUES WILL STEADILY INCREASE TO UP
NEAR 2 INCHES BEGINNING SUNDAY AFTERNOON/EVENING AS SOUTHWEST FLOW
CONTINUES. THIS WILL ALLOW FOR MOIST AND WARM CONDITIONS FROM THE
GULF OF MEXICO TO INFILTRATE INTO THE AREA...AND AS A RESULT...WILL
INCREASE SHOWER AND THUNDERSTORM CHANCES SUNDAY THROUGH TUESDAY.
LATEST GUIDANCES HAS THE COLD FRONT PUSHING THROUGH THE FORECAST
AREA TUESDAY AFTERNOON AND INTO THE EVENING HOURS WITH SFC HIGH
PRESSURE QUICKLY BUILDING IN BEHIND. WITH DRIER AIR SUBSTANTIALLY
DECREASING PRECIPITABLE WATER VALUES...HAVE KEPT WITH THE DRYING
TREND AND THUS HAVE MUCH LOWER POPS WEDNESDAY AND THURSDAY.
AS FOR TEMPERATURES...UPPER 80S TO LOWER 90S ARE EXPECTED SUNDAY
THROUGH TUESDAY...KEEPING THE VALUES JUST ABOVE CLIMATOLOGY. WITH
THE PASSAGE OF THE FRONT...THEY WILL DROP TO NEAR-CLIMATOLOGY...WITH
MAINLY MID TO UPPER 80S ACROSS THE BOARD. OVERNIGHT LOWS WILL REMAIN
IN THE LOWER 70S...DROPPING UPPER 60S/NEAR 70 BEHIND THE
FRONT...JUST ON THE CUSP OF CLIMATOLOGY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...A COLD FRONT DROPPING SOUTHWARD ALONG WITH SEA BREEZE
INTERACTIONS WILL PROVIDE THE FOCUS FOR ISO/SCT CONVECTION ALONG
THE COAST THIS AFTN. HAVE INCLUDED PREVAILING VCTS FOR KILM...KCRE
AND KMYR WITH TEMPO TSRA BASED ON THE LATEST HRRR TRENDS. BRIEF
PERIODS OF MVFR/IFR VSBYS AND GUSTY WINDS ARE POSSIBLE WITH
SHOWERS/T-STORMS THAT MOVE DIRECTLY OVER A TAF SITE. DRIER MID-
LEVEL AIR INLAND SHOULD LIMIT THE THREAT OF DEEP CONVECTION FOR
KLBT/KFLO...SO HAVE CHOSEN NOT TO MENTION PCPN ATTM. WEST WINDS
AROUND 10 KTS WILL VEER TO THE NORTHWEST LATER TODAY AND THEN THE
NORTHEAST FOLLOWING FROPA. THE FRONT SHOULD CLEAR OUR SOUTHERN
TERMS AROUND OR JUST AFTER 00Z. GFS FCST SOUNDINGS DEPICT POST-
FRONTAL MVFR/IFR CIGS DEVELOPING EARLY FRIDAY...SO HAVE INCLUDED
PREVAILING MVFR CIGS BEFORE 12Z. BEST CHANCES FOR IFR WOULD BE AT
KLBT/KILM...BUT CONFIDENCE IS LOW ATTM. VFR SHOULD PREVAIL DURING
THE DAY ON FRIDAY WITH E-NE WINDS AROUND 10 KTS.
EXTENDED OUTLOOK...EARLY MORNING IFR/MVFR CIGS/VSBYS POSSIBLE ON
SATURDAY...ESPECIALLY INLAND AT KLBT/KFLO. SCATTERED SHRA/TSRA
POSSIBLE MONDAY AND TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...AN EAST-WEST ORIENTED FRONT WILL SINK SOUTH
THROUGH THE WATERS THIS AFTERNOON INTO THIS EVENING. SOUTHWEST
WINDS WILL REMAIN IN PLACE AHEAD OF THE FRONT BUT WILL DECREASE
THROUGH THIS AFTERNOON AS THEY VEER AROUND TO MORE WESTERLY JUST AHEAD
OF THE COLD FRONT. OVERALL EXPECT SW TO W WINDS 10 TO 15 KTS WITH
HIGHER GUSTS AHEAD OF FRONT MAKING A SHARP TRANSITION TO THE NORTH
BEHIND THE FRONT.
THE COLD FRONT WILL REACH THE NORTHERN WATERS BY MID AND LATE
AFTERNOON AND SHOULD DROP SOUTH OF SOUTHERNMOST WATERS BY LATE
THIS EVE. WINDS WILL SHIFT TO THE N AND THEN NE LATER TONIGHT AS A
NE SURGE MOVES DOWN THE COAST AND ACROSS THE WATERS. SUSTAINED
WINDS WILL INCREASE TO AROUND 15 KT WITH HIGHER GUSTS OVERNIGHT
AND THIS WILL ALLOW SEAS TO BUILD. AT THIS TIME...WILL CAP SEAS AT
4 FT...BUT SOME 5 FOOTERS MAY DEVELOP BY FRI MORNING ACROSS
PORTIONS OF THE OUTERMOST WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...ALL MODELS SHOW THE SURFACE COLD FRONT
SHOULD BE SOUTH OF GEORGETOWN SC BY FRIDAY MORNING...WITH
NORTHEAST WINDS BEING PRODUCED BY HIGH PRESSURE ACROSS THE MID-
ATLANTIC WATERS. THESE WINDS SHOULD REACH A SOLID 15 KNOTS DURING
THE DAY FRIDAY...VEERING MORE EASTERLY AND DIMINISHING TO AROUND
10 KNOTS FRIDAY NIGHT. UNFORTUNATELY A SHORT-PERIOD CHOP AS HIGH
AS 3-4 FEET SHOULD ACCOMPANY THE WINDS FRIDAY...DIMINISHING DOWN
TOWARD 2 FEET SATURDAY. THE FRONT WILL BEGIN TO RETURN NORTH
SATURDAY WITH LIGHT WINDS TURNING SOUTHERLY BY SATURDAY NIGHT AS
THE FRONT MOVES THROUGH.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 3 PM THURSDAY...SOUTHWEST FLOW WILL CONTINUE ACROSS THE
WATERS INTO EARLY TUESDAY AHEAD OF AN APPROACHING COLD FRONT...WITH
SUSTAINED WINDS AROUND 10 TO 15 KTS...INCREASING UP TO 20 KTS INTO
MONDAY AND TUESDAY. OVERALL SEAS WILL RANGE FROM 2 TO 4 FEET SUNDAY
AND MONDAY...THOUGH LATEST MODELS ILLUSTRATE 5 FT SEAS POSSIBLE JUST
ON THE CUSP OF THE FORECAST AREA OUT 20 NM. AS THE FRONT PUSHES
CLOSER...CONDITIONS COULD WARRANT A SCEC...BUT HAVE NOT INTRODUCED
ONE ATTM.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TRA
NEAR TERM...RGZ
SHORT TERM...TRA
LONG TERM...SGL
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
254 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTH TONIGHT. HIGH PRESSURE
WILL BUILD INTO THE REGION FROM THE NORTH FRIDAY AND SATURDAY. THE
HIGH WILL GRADUALLY SHIFT OFFSHORE WITH ANOTHER COLD FRONT APPROACHING
TUESDAY BEFORE MOVING OFFSHORE ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 PM THURSDAY...AS ADVERTISED BY THE 3KM HRRR MODEL AND
OTHER HIGH RESOLUTION MODELS...PATCHY SHOWERS HAVE DEVELOPED NEAR
THE ALBEMARLE SOUND REGION AND ARE MOVING/SPREADING SOUTH AND
SOUTHWEST. WHILE THERE IS SOME MODERATE INSTABILITY...NO THUNDER
HAS BEEN OBSERVED AS MORNING CLOUD COVER LIKELY CUT DOWN ON ANY
WIDESPREAD CONVECTIVE POTENTIAL THIS EVENING. WITH PRECIPITABLE
WATER VALUES STILL AROUND 2 INCHES...THERE WILL BE SOME BRIEF
DOWNPOURS WITH THESE SHOWERS. GOOD AGREEMENT AMONGST THE VARIOUS
SHORT TERM MODELS THAT PRECIPITATION WILL WANE QUICKLY BEFORE
MIDNIGHT. WITH A LOW-LEVEL NORTHEAST FLOW...EXPECT STRATUS TO
BE LIKELY OVERNIGHT. LOW TEMPERATURES WILL GENERALLY BY IN THE 68
TO 72 DEGREE RANGE.
&&
.SHORT TERM /FRIDAY/...
AS OF 245 PM THURSDAY...FRIDAY WILL BE CHARACTERIZED BY A SLIGHTLY
DRIER AIRMASS WITH WARM TEMPERATURES IN THE MIDDLE TO UPPER 80S
AWAY FROM THE IMMEDIATE COAST. DEWPOINTS WILL DROP INTO THE UPPER
60S WITH A LIGHT NORTHEAST WIND AS HIGH PRESSURE BUILDS SOUTH
ACROSS THE MID-ATLANTIC. MAY START THE DAY WITH SOME LOW STRATUS
BUT IT SHOULD DISSIPATE AS THE DRIER AIR STARTS TO MIX TO THE
SURFACE BY MID MORNING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE
ACROSS THE AREA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE
WILL TRANSITION OFF THE COAST SAT WHILE A BOUNDARY PUSHES BACK
NORTH OVER THE REGION BY LATE AFTERNOON AS A WEAK WARM FRONT.
LITTLE IF ANY PRECIP IS EXPECTED TO OCCUR AS BOUNDARY LAYER WILL
REMAIN DRY...THOUGH AN ISO SHOWER/STORM POSSIBLE INLAND WITH SEA
BREEZE PROPAGATION AND WILL MAINTAIN ISOLATED POPS SAT
AFTERNOON...WITH BEST CHANCES ACROSS SOUTHERN CWA. SW RETURN FLOW
INCREASES SUN BRINGING WARM/MOIST CONDITIONS BACK TO THE AREA WITH
FORECAST SOUNDINGS INDICATING PWATS NEAR 2 INCHES. WILL CONTINUE
LOW END CHANCE POPS INLAND AND SLIGHT E OF HWY 17.
BY MON AN UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA WILL DIG
SOUTH AND EAST INTO THE GREAT LAKES REGION. SHORT WAVE ENERGY IN
BROAD SW FLOW WILL MOVE ACROSS THE REGION BRINGING A BETTER CHANCE
FOR ORGANIZED CONVECTION IN TANDEM WITH PIEDMONT TROUGH AND SEA
BREEZE...AND HAVE MAINTAINED CHANCE POPS ACROSS THE REGION. FOR
TUES...THE UPPER TROUGH WILL MOVE EAST FROM THE GREAT LAKES INTO
THE NORTHEASTERN STATES...DRAGGING A COLD FRONT THROUGH EASTERN NC
LATE TUE INTO TUE NIGHT. WILL CONTINUE GOOD CHANCE POPS TUE
TAPERING OFF BEHIND THE FRONT TUE NIGHT INTO WED. TEMPS THROUGH
THE PERIOD WILL BE NEAR CLIMO...WITH HIGHS GENERALLY IN THE MID
80S TO AROUND 90 DEGREES. THE WARMEST DAYS OF THE PERIOD LOOK LIKE
SUN AND MON. SLIGHTLY COOLER AND DRIER AIRMASS EXPECTED BEHIND THE
FRONT FOR WED/THU...THOUGH NO SIG TEMP SWINGS EXPECTED.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
SHORT TERM /TONIGHT AND FRIDAY/...
VFR/MVFR CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF
THE AFTERNOON AS A WEAK COLD FRONT SINKS FURTHER SOUTH.
SUFFICIENT LOW/MID LEVEL MOISTURE IS STILL IN PLACE WITH BKN
CEILINGS ACROSS MUCH OF THE AREA. LIGHT NORTHERLY FLOW WILL DIMINISH
OVERNIGHT WITH ATMOSPHERIC DRYING TAKING SHAPE. HOWEVER...GIVEN
CALM CONDITIONS AT THE SFC AND TEMPERATURES DROPPING A FEW DEGREES
BELOW THE CROSS OVER TEMP...FEEL FOG AND ESPECIALLY STRATUS WILL BE
AN ISSUE OVERNIGHT. ANTICIPATE MOST LOCATIONS TO DROP TO IFR
CIGS/MVFR CIGS...WITH THE POSSIBILITY OF DROPPING TO LIFR IN SOME
LOCATIONS...LIKELY BETWEEN 9-12Z. GIVEN SLOW MIXING IN THE
MORNING...MIGHT TAKE SOME TIME TO SCATTER OUT ANY LOW LEVEL MOISTURE
ACROSS THE REGION. VFR CONDITIONS ARE EXPECTED THROUGH TOMORROW
WITH DIURNAL CU FORMATION UNDER NELY FLOW.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...PRED VFR CONDITIONS EXPECTED THROUGH THE
PERIOD. A COLD FRONT WILL APPROACH FROM THE WEST MONDAY
NIGHT...MOVING THROUGH EASTERN NC LATE TUE AND TUE NIGHT. SCT
MAINLY DIURNAL SHOWERS/TSTMS POSSIBLE SUN THROUGH TUE WITH PERIODS
OF SUB-VFR POSSIBLE. WITH CALM TO LIGHT WINDS OVERNIGHT AND MOIST
BL...COULD SEE PATCHY FOG/STRATUS EACH NIGHT AND EARLY MORNING.
&&
.MARINE...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 255 PM THURSDAY...AS COLD FRONT SINKS SOUTH OF THE REGION
OVER THE NEXT FEW HOURS...AM SEEING A BIT OF A CAA SURGE. NE WINDS
AROUND GUSTING TO AROUND 20 KNOTS OVER THE SOUNDS AND NORTHERN
WATERS. THIS SURGE WILL MOVE SOUTH OVER THE NEXT FEW HOURS BEFORE
SUBSIDING LATE TONIGHT. LATEST LOCAL NWPS MODEL KEEPS SEAS AT 5
FEET OR BELOW. WINDS SHOULD GENERALLY BE NE AT 10 TO 15 KNOTS
AREA-WIDE ON FRIDAY...SEAS WILL RANGE FROM 3 TO 5 FEET NORTH TO 2
TO 4 FEET SOUTH.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE OVER
THE WATERS THIS WEEKEND INTO EARLY NEXT WEEK. OVERALL EXPECT
PLEASANT BOATING CONDITIONS THIS WEEKEND WITH VEERING WINDS 5-15KT
AND SEAS 2-4FT. A COLD FRONT WILL APPROACH THE WATERS FROM THE
WEST MON NIGHT INTO TUE...MOVING THROUGH TUE NIGHT INTO EARLY WED
MORNING. A BRIEF PERIOD OF SCA CONDITIONS WILL BE POSSIBLE MONDAY
EVENING...MAINLY FOR THE CENTRAL WATERS...AS GRADIENT TIGHTENS
AHEAD OF APPROACHING FRONT. SWLY WINDS EXPECTED TO INCREASE TO
15-20KT WITH SEAS BUILDING TO 6FT ACROSS THE OUTER CENTRAL WATERS.
SW FLOW 10-20KT WILL CONTINUE INTO TUE WITH SEAS 5FT OR LESS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC
SHORT TERM...CTC
LONG TERM...CQD
AVIATION...CQD/LEP
MARINE...CTC/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
213 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA...FROM NORTH TO
SOUTH...THROUGH THIS EVENING. HIGH PRESSURE WILL BUILD IN BEHIND
THE FRONT FOR THE WEEKEND. THE FRONT WILL RETURN NORTH DURING THE
WEEKEND WITH HOT AND HUMID CONDITIONS DEVELOPING EARLY NEXT WEEK.
A STRONGER COLD FRONT WILL ARRIVE FROM THE NORTH TUESDAY OR
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...COLD FRONT CONTINUES TO MAKE PROGRESS
SOUTHWARD AS IT EXTENDS WESTWARD FROM LOW PRESSURE CENTER
NORTHEAST OF CAPE HATTERAS. THE BEST CONVECTION AND LIGHTNING WITH
THIS SYSTEM REMAINS OUT OVER THE COASTAL WATERS EAST OF HATTERAS
CLOSE TO THE LOW AND WHERE BEST UPPER LEVEL SUPPORT EXISTS. AS
BOUNDARY SINKS SOUTH REACHING JUST NORTH OF LOCAL CWA...THE WINDS
WERE SHIFTING TO THE NORTH BEHIND IT AND A FEW SHOWERS WERE
STARTING TO POP UP JUST NORTH OF CWA AND STREAMING SOUTH. ALTHOUGH
THE WINDS WERE SHIFTING TO THE NORTH...THE DEWPOINT TEMPS WERE NOT
SHOWING MUCH OF A DROP WITH PLENTY OF MOISTURE AND CLOUDS WRAPPING
AROUND THE LOW WELL UP INTO THE MID ATLANTIC STATES THIS
AFTERNOON. EXPECT CLOUDS TO SPREAD SOUTH WITH INCREASING SHOWER
ACTIVITY AS FRONT DROPS THROUGH AREA THIS AFTERNOON INTO EARLY
THIS EVENING.
TEMPS IN THE MID TO UPPER 80S MOST PLACES BUT TAPERING OFF AS
CLOUDS SPREAD SOUTH. AREAS OF GREATER HEATING WILL AID IN
DESTABILIZING THE ATMOSPHERE MORE. LOOKING AT SOUNDING DATA AND
CONVECTIVE PARAMETERS...THE ML CAPE DOES INCREASE CLOSE TO 2000
J/KG WHILE DCAPES UP TO 1600 J/KG THIS AFTERNOON. THE OVERALL
PROFILE SHOWS FAIRLY DECENT DRY LAYER FROM THE SURFACE UP CLOSE TO
10 K FT. PCP WATER VALUES ACTUALLY DECREASE THROUGH THIS AFTERNOON
AS LAYER OF MOIST AIR BETWEEN 10 AND 20K FT GETS ERODED SOMEWHAT.
MID TO UPPER LEVELS REMAIN WARM WITH -5C TEMPS THIS AFTERNOON WITH
THE MID LEVEL LAPSE RATES REMAINING UNIMPRESSIVE AND MOISTURE
THROUGH THE COLUMN ACTUALLY DIMINISHES THROUGH THIS AFTERNOON.
ANOTHER FACTOR WILL BE THE ACTUAL FORCING MECHANISM TO INITIATE
ANY CONVECTION AS THE BEST MID TO UPPER LEVEL SUPPORT REMAINS
EAST OF MID TO UPPER TROUGH OVER THE ATLANTIC. A FEW MINOR
PERTURBATIONS IN THE MID TO UPPER LEVEL FLOW MAY ACT TO ENHANCE
SOME CONVECTIVE DEVELOPMENT...BUT OVERALL EXPECT BEST FORCING TO
COME FROM FRONT MOVING SOUTH AIDED BY CONVERGENCE ALONG SEA
BREEZE. THE SEA BREEZE SHOULD REMAINED PINNED CLOSER TO THE COAST
WITH A STRONGER W-SW FLOW. THE WESTERLY DOWNSLOPE COMPONENT TO THE
FLOW AHEAD OF THE FRONT WILL ALSO WORK AGAINST CONVECTIVE
DEVELOPMENT....BUT EXPECT MORE ISOLATED SHOWERS INLAND WITH BETTER
CONVECTIVE DEVELOPMENT AS FRONT INTERACTS WITH SEA BREEZE CLOSER
TO THE COAST....ESPECIALLY FROM CAPE FEAR SOUTH INTO NORTHEAST
SOUTH CAROLINA. MAIN ACTIVITY STILL FORECAST TO OCCUR AS FRONT
DROPS SOUTH AND INTERACTS WITH SEA BREEZE BETWEEN 2 PM TO 5 PM
OVER CAPE FEAR AND CONTINUING SOUTH MOVING OVER SOUTH CAROLINA
THROUGH THE LATE AFTERNOON INTO EARLY THIS EVENING. ALTHOUGH NOT
EXPECTING VERY WIDESPREAD OR DEEP CONVECTION...A FEW STORMS COULD
POTENTIALLY PRODUCE SOME VERY GUSTY WINDS INDICATIVE OF INVERTED-V
SOUNDING PROFILE AND DCAPES OF 1600 J/KG.
AS THE FRONT MOVES TO THE SOUTH OF THE SOUTH SANTEE RIVER DURING
THE LATE EVENING HOURS AND WINDS SHIFT AROUND TO THE NORTH TO
NORTHEAST...MORE STABLE AIR WILL ARRIVE FROM THE NORTH. THE RELATIVELY
COOLER AIR MAKING ITS WAY IN BEHIND THE FRONT COMBINING WITH
LINGERING MOISTURE AND EASTERLY COMPONENT TO THE FLOW COULD
PRODUCE SOME STRATUS AND FOG OVERNIGHT. LOWS TONIGHT WILL BE A
LITTLE TRICKY AS DEWPOINT TEMPS DROP TO THE MID 60S BUT CLOUDS AND
MOISTURE MAY LINGER IN LOW LEVELS. WILL HOLD MOST LOW TEMPS CLOSER
TO 70 WITH SOME 60S OVER NORTHERN TIER COUNTIES AS COOLER AND
DRIER AIR ADVECTS IN FROM THE NORTH.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...DISSIPATING FRONT WILL REMAIN STALLED SOUTH OF
THE AREA FRI AS DRIER HIGH PRESSURE TO THE NORTH WEAKLY BUILDS
SOUTH. LARGE AREA OF DEEP DRY AIR...PWATS UNDER 1.5 INCH...AND WEAK
MID LEVEL CAP WILL KEEP MOST OF THE AREA DRY. THE EXCEPTION ON FRI
COULD BE SOUTHERN SC COUNTIES. THE FRONT WILL BE IN CLOSE PROXIMITY
TO DEEPER MOISTURE AND COULD HELP GENERATE SOME ISOLATED AFTERNOON
CONVECTION.
WHAT IS LEFT OF THE STALLED FRONT SAT MORNING WILL LIFT NORTH AS
BERMUDA HIGH BUILDS BACK IN FROM THE EAST. THE RESULTING SOUTHERLY
FLOW WILL HELP WARM/MOISTEN THE LOW LEVELS BUT DRY AIR AND
WEST-NORTHWEST FLOW ALOFT WILL AGAIN CONTRIBUTE TO LIMITED COVERAGE
OF AFTERNOON CONVECTION. ILL DEFINED MID LEVEL PATTERN AND LACK OF
SIGNIFICANT FORCING WILL ALSO PLAY A ROLE IN LIMITING PRECIP
COVERAGE. DEEPEST MOISTURE REMAINS OVER SC COUNTIES SO WILL CONTINUE
WITH HIGHEST POP TO THE SOUTH.
HIGH TEMPERATURES NEAR CLIMO FRI WILL WARM SLIGHTLY ON SAT AS RETURN
FLOW STARTS TO DEVELOP. LOWS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO
EACH NIGHT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...SUMMER PATTERN IN PLACE AT THE START OF THE
WEEK WITH BERMUDA HIGH AND PIEDMONT TROUGH UNDER WEAKLY ZONAL FLOW
ALOFT. DEEP TROPICAL MOISTURE SPREADING NORTH FROM FL/GOMEX
ASSOCIATED WITH A WEAK TROPICAL WAVE WILL INCREASE SHOWER AND
THUNDERSTORM POTENTIAL SUN. STRENGTHENING MID LEVEL TROUGH MON
AHEAD OF COLD FRONT AND SHORTWAVE TROUGH MOVING INTO THE SOUTHEAST
LATER MON INTO TUE WILL FURTHER INCREASE SHOWER AND THUNDERSTORM
CHANCES. HIGHEST POP WILL BE ON MON...HIGH CHC...BUT ACTIVITY WILL
SPILL OVER INTO TUE AS FRONT IS NOT EXPECTED TO PUSH OFF THE COAST
UNTIL SOMETIME TUE AFTERNOON. WILL MAINTAIN INHERITED LOW CHC POP
FOR TUE THEN DRY THINGS OUT TUE NIGHT AND BEYOND AS HIGH PRESSURE
AND MUCH DRIER AIR BUILDS IN FROM THE NORTHWEST. PRECIPITABLE WATER
VALUES ARE BASICALLY CUT IN HALF...DROPPING FROM OVER 2 INCHES
SUN/MON TO UNDER AN INCH BY THE END OF THE PERIOD.
TEMPERATURES START OUT ABOVE CLIMO...BOTH LOWS AND HIGHS THROUGH MON
NIGHT BEFORE COLD FRONT PASSAGE ON TUE BRINGS A COOLER AND DRIER AIR
MASS FOR THE END OF THE PERIOD. HIGHS WILL BE SOLIDLY IN THE 90S SUN
AND MON...POTENTIALLY TUE IF FRONT IS SLOWER...THEN DROP BACK CLOSER
TO CLIMO...MID TO UPPER 80S WED. LOWS WELL ABOVE CLIMO FOR MUCH
OF THE PERIOD DROP A LITTLE BY MID WEEK...THOUGH STILL SEVERAL
DEGREES ABOVE CLIMO.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...A COLD FRONT DROPPING SOUTHWARD ALONG WITH SEA BREEZE
INTERACTIONS WILL PROVIDE THE FOCUS FOR ISO/SCT CONVECTION ALONG
THE COAST THIS AFTN. HAVE INCLUDED PREVAILING VCTS FOR KILM...KCRE
AND KMYR WITH TEMPO TSRA BASED ON THE LATEST HRRR TRENDS. BRIEF
PERIODS OF MVFR/IFR VSBYS AND GUSTY WINDS ARE POSSIBLE WITH
SHOWERS/T-STORMS THAT MOVE DIRECTLY OVER A TAF SITE. DRIER MID-
LEVEL AIR INLAND SHOULD LIMIT THE THREAT OF DEEP CONVECTION FOR
KLBT/KFLO...SO HAVE CHOSEN NOT TO MENTION PCPN ATTM. WEST WINDS
AROUND 10 KTS WILL VEER TO THE NORTHWEST LATER TODAY AND THEN THE
NORTHEAST FOLLOWING FROPA. THE FRONT SHOULD CLEAR OUR SOUTHERN
TERMS AROUND OR JUST AFTER 00Z. GFS FCST SOUNDINGS DEPICT POST-
FRONTAL MVFR/IFR CIGS DEVELOPING EARLY FRIDAY...SO HAVE INCLUDED
PREVAILING MVFR CIGS BEFORE 12Z. BEST CHANCES FOR IFR WOULD BE AT
KLBT/KILM...BUT CONFIDENCE IS LOW ATTM. VFR SHOULD PREVAIL DURING
THE DAY ON FRIDAY WITH E-NE WINDS AROUND 10 KTS.
EXTENDED OUTLOOK...EARLY MORNING IFR/MVFR CIGS/VSBYS POSSIBLE ON
SATURDAY...ESPECIALLY INLAND AT KLBT/KFLO. SCATTERED SHRA/TSRA
POSSIBLE MONDAY AND TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...AN EAST-WEST ORIENTED FRONT WILL SINK SOUTH
THROUGH THE WATERS THIS AFTERNOON INTO THIS EVENING. SOUTHWEST
WINDS WILL REMAIN IN PLACE AHEAD OF THE FRONT BUT WILL DECREASE
THROUGH THIS AFTERNOON AS THEY VEER AROUND TO MORE WESTERLY JUST AHEAD
OF THE COLD FRONT. OVERALL EXPECT SW TO W WINDS 10 TO 15 KTS WITH
HIGHER GUSTS AHEAD OF FRONT MAKING A SHARP TRANSITION TO THE NORTH
BEHIND THE FRONT.
THE COLD FRONT WILL REACH THE NORTHERN WATERS BY MID AND LATE
AFTERNOON AND SHOULD DROP SOUTH OF SOUTHERNMOST WATERS BY LATE
THIS EVE. WINDS WILL SHIFT TO THE N AND THEN NE LATER TONIGHT AS A
NE SURGE MOVES DOWN THE COAST AND ACROSS THE WATERS. SUSTAINED
WINDS WILL INCREASE TO AROUND 15 KT WITH HIGHER GUSTS OVERNIGHT
AND THIS WILL ALLOW SEAS TO BUILD. AT THIS TIME...WILL CAP SEAS AT
4 FT...BUT SOME 5 FOOTERS MAY DEVELOP BY FRI MORNING ACROSS
PORTIONS OF THE OUTERMOST WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...NORTHEAST FLOW OF 10 TO 15 KT AT THE START OF
THE PERIOD WILL WEAKEN AS GRADIENT RELAXES FRI INTO FRI NIGHT. WINDS
WILL BECOME SOUTHERLY SAT AS RETURN FLOW AROUND BERMUDA HIGH
DEVELOPS. GRADIENT SAT AND SAT NIGHT REMAINS WEAK WITH SPEEDS 10
KT OR LESS FOR THE SECOND HALF OF THE PERIOD. SEAS 2 TO 4 FT AT
THE START OF THE PERIOD WILL SUBSIDE TO 2 TO 3 FT FRI NIGHT AND 2
FT SAT/SAT NIGHT.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...SOUTH TO SOUTHWEST FLOW WILL CONTINUE WITH
WATERS BETWEEN BERMUDA HIGH AND PIEDMONT TROUGH. COLD FRONT WELL
NORTHWEST OF THE AREA WILL SLOWLY APPROACH THE WATERS. AS THE
FRONT MOVES CLOSER THE GRADIENT WILL SLOWLY TIGHTEN...PUSHING
SPEEDS TO 10 TO 15 KT SUN AND 15 TO 20 KT FOR MON. LATEST
FORECASTS KEEP SEAS UNDER 6 FT THROUGH THE END OF THE PERIOD BUT
SOME 5 FT DO GET INTO PORTIONS OF THE WATERS NEAR 20 NM. COULD SEE
HEADLINES BEING REQUIRED LATE MON AND MON NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
134 PM EDT THU AUG 29 2013
.SYNOPSIS...
A FRONTAL BOUNDARY SHIFTS SOUTH INTO NORTH CAROLINA THIS AFTERNOON.
WEAK HIGH PRESSURE SHOULD BUILD INTO THE AREA BEHIND IT FOR
THIS AFTERNOON INTO FRIDAY BEFORE SLIDING OFFSHORE BY SATURDAY.
THIS WILL BRING A RETURN FLOW OF MOISTURE ALONG WITH AN ASSOCIATED
WARM FRONT LATER IN THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 125 PM EDT THURSDAY...
MADE SOME MINOR ADJUSTMENTS IN POPS AND TEMPERATURES FOR THIS
AFTERNOON INTO THIS EVENING.
AS OF 940 AM EDT THURSDAY...
THIS MORNING 8AM/12Z RNK SOUNDING SHOWED PLENTY OF MOISTURE
UP TO 640 MB WITH A NORTHERLY FLOW. KFCX 88D INDICATED WIDELY
SCATTERED SHOWERS TRAVELING SOUTH THIS MORNING. COLD FRONT ACROSS
SOUTHERN PORTIONS OF CWA THIS MORNING WILL SLOWLY DRIFT SOUTH
TODAY. MADE SOME ADJUSTMENTS IN THE POPS TO SHAPE TOWARDS RADAR
TRENDS AND HRRR FOR NEXT COUPLE OF HOURS...THEN KEPT THE SCATTERED
STORMS IN FOR THE AFTERNOON INTO TONIGHT. THE BEST CHANCE REMAIN
ALONG THE SOUTHERN BLUE RIDGE THIS AFTERNOON WITH MOISTURE
CONVERGENCE. HIGH PRESSURE BUILDS SOUTH ACROSS THE REGION
TONIGHT. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE
UPPER 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONT.
AS OF 315 AM EDT THURSDAY...
SOUPY AIRMASS IN PLACE THIS MORNING WITH TEMPS STILL RUNNING IN THE
70S OVER MUCH OF THE AREA. FRONTAL BOUNDARY SITUATED FROM LOW
PRESSURE OVER VA TIDEWATER NORTHWEST INTO NRN WV THEN INTO SRN
OHIO. HIGHER THETA-E ACROSS ERN KY/SRN WV SHIFTING SE INTO THE NC
MTNS WILL KEEP SHOWERS AROUND THRU AT LEAST MID MORNING...BUT
MAINLY ISOLATED.
AT THE MOMENT SKIES HAVE CLEARED OVER THE FOOTHILLS AND PIEDMONT
THANKS TO A CONSISTENT NNW FLOW DOWNSLOPING WIND. THIS WILL CHANGE
THRU DAYBREAK AS THE FLOW COMES AROUND TO THE NORTH THEN NORTHEAST.
STILL HINGING ON CLOUDS INCREASING ALONG THE BLUE RIDGE AND POINTS
EAST BUT THEN SLOWLY MIXING OUT TOWARD MIDDAY. THE 00Z CMC HAS A
PRETTY GOOD HANDLE EARLY...BUT DOES NOT REALLY ENHANCE LOW CLOUDS
DEVELOPING OVER THE BLUE RIDGE LIKE THE NAM DOES...SO LEANED TOWARD
A BLEND OF THE TWO.
THROUGH THE DAY...WILL BE DEALING WITH SOME DRYING ALOFT...BUT
KEEPING THE LOW LVLS MOIST...AS NOT MUCH CHANGE IN AIRMASS EXPECTED.
THERE WILL BE ENOUGH LOW LEVEL CONVERGENCE AROUND NEAR THE FRONT
THAT AT LEAST ISOLATED SHOWERS OR STORMS OCCUR THIS AFTERNOON. STILL
LOOKS LIKE THE SRN BLUE RIDGE HAS THE BEST CHANCE OF SEEING
SCATTERED COVERAGE GIVEN THE FORECAST CONVERGENCE PATTERN IN THE
WINDS.
GIVEN A LACK OF UPSTREAM CONVECTION AND CLOUDS...THINK THE SUN WILL
BREAK THROUGH TOWARD EARLY AFTERNOON IN THE NORTH...THEN MID
AFTERNOON ELSEWHERE. THESE LOWER CLOUDS MAY BE HARD TO MIX OUT UNTIL
LATE MORNING. FOR THE AFTERNOON ENOUGH SUN WILL AVAILABLE TO REALIZE
WARMER HIGHS...BUT SOUPY AIRMASS WILL STILL CUT INTO REALLY WARM
TEMPS...SO WENT CLOSE TO OR JUST BELOW MAV MOS WITH UPPER 70S/LOWER
80S WEST TO MID TO UPPER 80S ACROSS THE SOUTHERN SHENANDOAH
SOUTHEAST INTO SOUTHSIDE VA AND THE NC PIEDMONT/FOOTHILLS.
LOW LVLS WINDS CONTINUE TO SHIFT TOWARD THE EAST THEN SOUTHEAST LATE
TONIGHT AS HIGH PRESSURE NOSES SOUTH OVER THE ALLEGHANY HIGHLANDS.
STILL ENOUGH CONVERGENCE AND LOW LVL MOISTURE TO HANG ONTO POPS OF
THE 20/30 VARIETY OVER THE SOUTHERN BLUE RIDGE AND ADJACENT AREAS
THIS EVENING...GRADUALLY SHRINKING TO SLIGHT CHANCE OVER THE NC MTNS
AFTER MIDNIGHT. ENOUGH DRY AIR MAY ALLOW TEMPS TO FALL IN THE NRN
CWA TO THE LOWER 60S TONIGHT...WITH MID TO UPPER 60S PREVALENT
ELSEWHERE.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 400 AM EDT THURSDAY...
THE STRONG UPPER HIGH OVER THE MIDWEST WILL WEAKEN AS IT MOVES TO
THE FOUR CORNERS REGION LATE THIS WEEKEND. AS HEIGHTS LOWER OVER THE
SOUTHEASTERN/GULF COAST STATES...AND AN UPPER TROUGH STRENGTHENS
OVER THE GREAT LAKES...SOUPY HIGH PWAT AIR WILL BE FORCED NORTH FROM
THE GULF OF MEXICO AS WINDS BECOME S AND SW EVENTUALLY. BEFORE
THIS...JUST GARDEN VARIETY STORMS ACROSS EXTREME SW VA AND NW NC FOR
FRIDAY. GOOD UPSLOPE COMPONENT MOST OF THE DAY MAY KEEP SPOTS ALONG
THE SOUTHERN HALF OF THE BLUE RIDGE BELOW 80F. ALTHOUGH BOTH
SATURDAY AND SUNDAY HAVE THE POTENTIAL FOR SLOW MOVING STORMS AND
WATER PROBLEMS...ESPECIALLY ACROSS NW NC...AN UPPER WAVE WILL BE
INVOLVED SUNDAY WHICH SHOULD INCREASE COVERAGE. DESPITE A LOT OF
CLOUDS AND STORMS AROUND...H85 TEMPS IN THE UPPER TEENS WILL STILL
GET SOME SPOTS INTO THE MID 80S. STORMS WILL PROBABLY MORE SCATTERED
ACROSS THE SOUTHSIDE AND NC PIEDMONT THIS WEEKEND...SUCH THAT UPPER
80S MAY BE POSSIBLE THERE. ELSEWHERE...GUIDANCE TEMPS WILL PROBABLY
CONTINUE THEIR CURRENT WARM BIAS SO WENT A FEW DEGREES BELOW ON MAX
T EVERYWHERE ELSE.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 245 PM EDT WEDNESDAY
THE GFS/ECMWF/CANADIAN/GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT THAT
THE UPPER TROF...WHICH HAS BEEN PERSISTENT ACROSS THE EASTERN U.S.
FOR MOST OF THE SUMMER...AMPLIFIES BY EARLY NEXT WEEK.
THERE ARE SOME MINOR DIFFERENCE WITH REGARD TO AMPLIFICATION WITH
THE ECMWF FORECASTING A SLIGHTLY DEEPER/SLOWER EASTERN U.S. TROF
COMPARED TO THE GFS AND CANADIAN MODELS. WITH THE BLOCKY
PATTERN...LEANED TOWARD THE STRONGER ECWMF SOLUTION.
AS THE UPPER TROF DEEPENS...A STRONG COLD FRONT WILL PUSH THROUGH
MONDAY NIGHT/EARLY TUESDAY BRINGING COOLER TEMPS...DRIER
WEATHER...AND LOWER DEW POINTS FOR TUESDAY AND WEDNESDAY.
BEFORE THE FRONTAL PASSAGE...DIURNALLY DRIVEN SHOWERS AND STORMS
WILL BE FOUND SUNDAY AND MONDAY. LOCALLY HEAVY RAIN WILL BE POSSIBLE
AS PWATS WILL BE 1-2 STANDARD DEVIATIONS ABOVE NORMAL PER THE GEFS.
FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WENT BELOW GFS MOS
GUIDANCE FOR TEMPS WITH THE GEFS SHOWING 850MB TEMPS 1-2 STANDARD
DEVIATIONS BELOW NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 130 PM EDT THURSDAY...
WEAK COLD FRONT WILL CONTINUE TO SINK SOUTH INTO THE
CAROLINAS...AS HIGH PRESSURE BUILD INTO OUR REGION FROM THE NORTH.
SCT TO BKN MVFR CLOUDS EXPECTED THIS AFTERNOON INTO TONIGHT.
MOST OF THE SHOWER/STORMS THIS AFTERNOON INTO TONIGHT WILL BE
CONFINED TO THE SOUTHERN BLUE RIDGE SOUTH OF ROA/BCB AND SOUTH OF
BLF. THEREFORE LEAVING ANY MENTION OUT OF THE TAFS GIVEN THREAT IS
20 PERCENT OR LESS.
THIS EVENING INTO TONIGHT...THE HIGH PRESSURE BEHIND THE FRONT
MOVES IN AND SKIES SHOULD CLEAR ENOUGH FOR FOG TO FORM AT MOST
STATIONS. DENSE FOG WILL OCCUR AT LWB/BCB WITH IFR VSBYS AT LYH.
MAYBE SOME LOWER CLOUDS MVFR AT ROA/DAN AND IFR AT BLF.
FOG/LOW CLOUDS ERODE FRIDAY MORNING...WITH A RETURN TO OVERALL
VFR CONDITIONS UNDER HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS
AT BEST FRIDAY AFTERNOON AND SATURDAY. DEEPER MOISTURE WILL MAKE A
RETURN LATER IN THE WEEKEND WITH MORE IN THE WAY OF CONVECTIVE
DRIVEN SUB-VFR CONDITIONS POSSIBLE WITH A PASSING WARM FRONT
SUNDAY...AND ANOTHER COLD FRONT LATER MONDAY. OTHERWISE SOME
PATCHY FOG LIKELY DURING THE OVERNIGHTS INTO SATURDAY...WITH LATE
NIGHT/EARLY MORNING MVFR/IFR CONDITIONS POSSIBLE ESPECIALLY AT THE
VALLEY LOCATIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP/KK
NEAR TERM...KK/WP
SHORT TERM...KM
LONG TERM...PH
AVIATION...KK/WP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1215 PM CDT THU AUG 29 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT THU AUG 29 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST...STRONG SUBTROPICAL
RIDGING OVER THE CENTRAL PLAINS AND TROUGHING ALONG THE EAST COAST
OF THE U.S.. ROUNDING THE SUBTROPICAL RIDGE WAS A CLUSTER OF
SHORTWAVES OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA.
SHOWERS AND THUNDERSTORMS HAVE BEEN ACCOMPANYING THESE SHORTWAVES...
WHICH ALSO ARE BEING AIDED BY MOISTURE TRANSPORT FROM SOUTHERLY
20-30 KT 850MB WINDS PER RADAR VWP DATA ACROSS THE WESTERN DAKOTAS.
EASTERN EXTENT OF THIS MOISTURE TRANSPORT HAS PRODUCED SOME STORMS
NEAR FARGO. FARTHER EAST OVER THE FORECAST AREA...CONDITIONS HAVE
REMAINED DRY THUS FAR DUE TO LITTLE IF ANY FORCING AS WELL AS STILL
SOME DRY AIR ABOVE THE SURFACE LINGERING AROUND AS SEEN IN THE 00Z
MPX SOUNDING. SURFACE MOISTURE REMAINS HIGH...ESPECIALLY OVER
NORTHERN IOWA AND SOUTHERN MN WHERE DEWPOINTS ARE IN THE LOW 70S.
THIS HIGHER MOISTURE IS POOLED ALONG A WARM FRONTAL BOUNDARY
BISECTING IOWA NORTHWEST TO SOUTHEAST. AIRMASS REMAINS WARM ACROSS
THE UPPER MIDWEST...WITH 925MB TEMPS AT 00Z RANGING FROM 22C AT
GRB...TO 25C AT MPX AND DVN...AND 27-29C AT ABR...BIS AND OAX.
..HAZARDS..
1. HEAT. HEAT INDICES ARE AGAIN EXPECTED TO CLIMB INTO THE 90 TO 100
RANGE...HIGHEST IN NORTHEAST IOWA...BUT STILL NOT HIGH ENOUGH TO
WARRANT A HEAT ADVISORY MENTION.
2. STORMS. BULK OF THE STORM ACTION IS EXPECTED NORTH OF THE
FORECAST AREA THROUGH TONIGHT. HOWEVER...THERE IS A SMALL CHANCE
SOME OF THE STORMS COULD ROLL THROUGH LOCATIONS NORTHEAST OF I-94
TONIGHT AND PRODUCE LARGE HAIL AND DAMAGING WINDS.
..SYNOPTIC OVERVIEW..
29.00Z MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A RETROGRESSION
WESTWARD OF THE SUBTROPICAL RIDGE INTO COLORADO BY 12Z FRIDAY.
MEANWHILE...THE CLUSTER OF SHORTWAVES PRESENTLY TOPPING THE GENERAL
RIDGING ARE PROGGED TO CONTINUE MARCHING EAST...REACHING LAKE
SUPERIOR AND UPPER MICHIGAN BY 12Z FRIDAY. AS THESE SHORTWAVES PRESS
EAST...THE WARM FRONTAL BOUNDARY IN IOWA GETS LIFTED NORTHEAST...
PERHAPS ALL THE WAY INTO UPPER MI BY 12Z FRIDAY. ADDITIONALLY...ALL
INDICATIONS ARE THAT A LOW PRESSURE AREA WILL ACCOMPANY THE
SHORTWAVES...WHICH IS ALREADY EVIDENT OVER FAR SOUTHWEST NORTH
DAKOTA.
..DETAILS..
29.00Z MODEL GUIDANCE HAS DEFINITELY TRENDED DRIER FOR THE FORECAST
AREA FOR BOTH TODAY AND TONIGHT...A TREND THAT STARTED WITH THE
28.12Z MODEL GUIDANCE AND PREVIOUS FORECAST. IN FACT...THE 29.00Z
REGIONAL CANADIAN IS COMPLETELY DRY. CERTAINLY GIVEN THE TRACK OF
THE SHORTWAVES AND SURFACE LOW...CONFIDENCE IS VERY HIGH THAT
LOCATIONS NORTH OF HERE FROM NORTHERN MN THROUGH NORTHWEST WI AND
UPPER MI WILL SEE SHOWERS AND STORMS. THE ONLY QUESTION MARK IS IF
THE WARM FRONT LIFTING THROUGH THE AREA CAN SPARK ANY CONVECTION...
EITHER DRIVEN BY 310-315K ISENTROPIC LIFT / 850MB MOISTURE
TRANSPORT...OR THROUGH SURFACE BASED CONVECTION. THERE IS A THIRD
SCENARIO PRESENTED BY THE 29.00Z NAM...WHERE SOME OF THE CONVECTION
COMING OUT OF NORTH DAKOTA THIS MORNING ROLLS DOWN ALONG THE
FRONT...IMPACTING LOCATIONS ALONG/WEST OF THE MS RIVER. HOWEVER...
HRRR TRENDS SUGGEST THIS WILL NOT HAPPEN...WHICH MAKES SENSE TOO AS
THE STRONGEST LOW LEVEL MOISTURE TRANSPORT REMAINS AIMED NORTHWEST
AND NORTH OF THE AREA. CHECKING OUT SURFACE BASED CONVECTION
POTENTIAL...MODIFYING A VARIETY OF SOUNDINGS FROM THE RAP AS WELL AS
THE 29.00Z GFS ALL SHOW A CAP HOLDING IN PLACE...LOCATED AROUND
775MB. THIS CAP ORIGINATES FROM WARM AIR BEING ADVECTED IN SOUTH OF
THE SHORTWAVE TRACK. IMPRESSIVE TO SEE THAT ALL OF TODAY THE 29.00Z
GFS DOES NOT PRODUCE ANY PRECIPITATION...WHICH THAT SIGNAL ALONE
LENDS MORE CONFIDENCE TO A DRY FORECAST. TO HELP BLEND WITH
NEIGHBORING OFFICES TO THE NORTH...HAVE MAINTAINED 20 PERCENT
CHANCES ACROSS FAR NORTHERN PORTIONS OF THE FORECAST AREA.
AS WE HEAD INTO TONIGHT...THE 29.00Z GFS/NAM/ECMWF INDICATE
POTENTIAL FOR SOME CONVECTION NORTHEAST OF I-94 AS THE LOW LEVEL JET
STRENGTHENS. FEEL IT IS PRUDENT TO HAVE A 20-40 PERCENT CHANCE IN THIS
AREA. OTHERWISE CAPPING AND DRY CONDITIONS SHOULD DOMINATE THE REST
OF THE FORECAST AREA.
MUCH OF THE WARM ADVECTION TODAY OCCURRING SOUTH OF THE TRACK OF THE
SHORTWAVES IS PROGGED TO OCCUR UP IN THAT 700-800MB LAYER. 925MB
TEMPERATURES REALLY DO NOT RESPOND IN OUR FORECAST AREA UNTIL AFTER
00Z. 925MB READINGS ARE PROGGED VERY SIMILAR TO YESTERDAY...
THEREFORE...ANTICIPATING SIMILAR HIGHS. WITH DEWPOINTS RUNNING IN
THE UPPER 60S TO MID 70S...WE SHOULD SEE YET AGAIN ANOTHER DAY OF
HEAT INDICES IN THE 90-100 RANGE...HIGHEST OVER NORTHEAST IA WHERE
HIGHEST TEMPERATURES AND DEWPOINTS ARE EXPECTED. ANOTHER WARM NIGHT
ON TAP TONIGHT AS WARMER 925MB SURGES IN AND DEWPOINTS REMAIN UP.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM CDT THU AUG 29 2013
..HAZARDS..
1. HEAT. HEAT INDICES HAVE COME DOWN SLIGHTLY ACROSS NORTHEAST IOWA
FOR FRIDAY...NOW IN THE 95-100 RANGE. SATURDAY HAS ALSO COME
DOWN...NOW MOSTLY AT OR BELOW 90. SO IT IS POSSIBLE NOW THAT WE CAN
GET THROUGH LABOR DAY WEEKEND WITHOUT ANY HEAT ADVISORIES...A BIG
CHANGE FROM WHAT THINGS LOOKED LIKE 4-7 DAYS AGO.
..SYNOPTIC OVERVIEW..
FOCUS FOR MUCH OF THE LONG TERM PERIOD IS THE IMPACT THE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST WILL HAVE ON THE FORECAST
AREA. THIS TROUGH IS PROGGED TO BEGIN EJECTING OUT ON FRIDAY...
CAUSING RIDGING TO BUILD OVER THE NORTHERN PLAINS...AND IN RESPONSE
TURNING THE UPPER FLOW MORE NORTHWESTERLY OVER THE FORECAST AREA.
THIS NORTHWEST FLOW WILL HELP DRIVE A COLD FRONT THROUGH THE AREA ON
FRIDAY. HEADING INTO THE WEEKEND...THE TROUGH IS EXPECTED TO MARCH
ACROSS SOUTHERN CANADA...WITH GOOD MODEL AGREEMENT FOR IT TO DIG
INTO THE WESTERN GREAT LAKES REGION ON SUNDAY. A WARM FRONTAL
PASSAGE IS LIKELY AHEAD OF THE TROUGH LATE SATURDAY...FOLLOWED BY A
FAIRLY STRONG COLD FRONTAL PASSAGE SUNDAY MORNING. ALL INDICATIONS
ARE THAT THIS TROUGH WILL EVENTUALLY ENCOMPASS MUCH OF THE EASTERN
THIRD OF THE U.S. BY TUESDAY...ALLOWING HIGH PRESSURE TO COME INTO
THE FORECAST AREA AT THE SURFACE. THE FORECAST BEYOND TUESDAY IS
MORE UNCERTAIN...PARTICULARLY DRIVEN BY THE ECMWF WHICH SHOWS A VERY
POTENT NORTHERN STREAM SHORTWAVE TROUGH DROPPING DOWN INTO THE
WESTERN GREAT LAKES REGION ON WEDNESDAY. THE 29.00Z GFS/CANADIAN
SHOW THIS SAME FEATURE TOO...BUT KEEP IT MORE PROGRESSIVE AND
IMPACTING SOUTHEAST CANADA INSTEAD. THE TWO SCENARIOS ARE
DRAMATICALLY DIFFERENT WHEN IT COMES TO BOTH PRECIPITATION AND
TEMPERATURE FORECASTS.
..DETAILS..
WITH A COLD FRONT COMING THROUGH ON FRIDAY...THERE ARE QUESTIONS ON
CAN IT PRODUCE ANY PRECIPITATION...AS WELL AS ITS TIMING FOR IMPACT
ON TEMPERATURES. MODELS HAVE DEFINITELY SPED UP ON THE COLD FRONTAL
TIMING...ESPECIALLY THE 29.00Z ECMWF/CANADIAN...HAVING IT NOW REACH
DVN BY 00Z SATURDAY. IF THIS TREND CONTINUES...WE MAY NOT HAVE ANY
CONVECTION ON FRIDAY. HOWEVER...THE 29.00Z GFS/REGIONAL CANADIAN/NAM
DEPICT A SLOWER TIMING...SO HAVE KEPT SOME 20-30 PERCENT CHANCES
GOING FOR NOW. THE SPEEDING UP OF THE FRONT ALSO HELPS TO PUSH THE
SURGE OF WARM AIR COMING IN HERE TONIGHT SOUTHEAST QUICKER. AS A
RESULT...HIGHS HAVE BEEN LOWERED SLIGHTLY...WHICH ALSO LOWERS HEAT
INDICES.
MAINLY DRY CONDITIONS LOOK TO PREVAIL FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BECOMES FIRMLY IN CONTROL. LOWERED TEMPERATURES A
BIT DURING THIS PERIOD AS THE AIR COMING IN IS A LITTLE COOLER THAN
PREVIOUSLY FORECAST.
THE WARM AIR SURGE AS WELL AS MOISTURE TRANSPORT AHEAD OF THE POTENT
SHORTWAVE CROSSING SOUTHERN CANADA COMES ACROSS THE AREA SATURDAY
NIGHT. 29.00Z GFS/ECMWF/NAM/CANADIAN ARE ALL IN GOOD AGREEMENT
SHOWING SOME SHOWERS AND THUNDERSTORMS IN THIS WARM ADVECTION SURGE
COMING INTO THE FORECAST AREA...ESPECIALLY AFTER MIDNIGHT. RAISED
CHANCES TO 40-50...HIGHEST OVER WESTERN PORTIONS OF THE FORECAST
AREA. SOME OF THESE CHANCES PERSIST INTO SUNDAY WITH THE COLD FRONT
COMING THROUGH. AS IT STANDS RIGHT NOW...THE BULK OF THE COLD
ADVECTION BEHIND THE FRONT APPEARS TO WAIT UNTIL AFTER SUNSET SUNDAY.
BEYOND SUNDAY...HIGH PRESSURE DOMINATES FOR THE MOST PART EXCEPT FOR
POSSIBLY A COLD FRONTAL PASSAGE ON WEDNESDAY PER 28.12Z/29.00Z
ECMWF. BOTH ECMWF MODELS SUGGEST THE FRONT WILL HAVE LITTLE MOISTURE
TO WORK WITH SO IT COMES THROUGH DRY. THEREFORE...DRY CONDITIONS ARE
FORECAST BEYOND SUNDAY. THE BIGGER THING WILL BE TEMPERATURES. 925MB
TEMPS PLUMMET FROM 22-25C ON SATURDAY...TO 18-22C ON SUNDAY...AND
14-17C ON MONDAY. GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
POSSIBLY WEDNESDAY AS WELL...DEPENDING ON IF THAT COLD FRONT COMES
THROUGH OR NOT. LAST NOTE WOULD BE POTENTIAL FOR VALLEY FOG TUESDAY
MORNING...BUT TOO EARLY TO PUT THAT IN THE FORECAST AT THIS TIME
GIVEN HOW SENSITIVE VALLEY FOG CAN BE TO OTHER VARIABLES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1215 PM CDT THU AUG 29 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A WEAK
FRONTAL BOUNDARY WILL APPROACH THE TAF SITES FROM WESTERN
MINNESOTA TONIGHT BRINGING AN INCREASE IN MID LEVEL CLOUDS.
ALSO...A WEAK LOW LEVEL JET DEVELOPS TONIGHT WITH WINDS
INCREASING TO AROUND 30 KTS AT 1200FT. WILL HAVE TO KEEP A VERY
CLOSE EYE ON THE POTENTIAL FOR LOW LEVEL WIND SHEAR LATE TONIGHT
INTO EARLY FRIDAY MORNING. OTHERWISE...THE FRONT WILL MAKE ITS WAY
ACROSS THE TAF SITES LATE TONIGHT INTO EARLY MONDAY MORNING WITH
WINDS SWITCHING TO THE NORTH AT 9 TO 12 KTS IN ITS WAKE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP