Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/01/14
AREA FORECAST DISCUSSION
NWS TAUNTON MA
739 PM EDT SUN AUG 31 2014
.SYNOPSIS...
A WARM HUMID FLOW WILL CONTINUE ACROSS NEW ENGLAND THROUGH
TUESDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS FROM TIME TO
TIME. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT THEN WARM BUT
LESS HUMID WEATHER WILL FOLLOW FOR WEDNESDAY THROUGH FRIDAY.
ANOTHER COLD FRONT MAY BRING A CHANCE OF SHOWERS AND THUNDERSTORMS
NEXT SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
730 PM UPDATE...
MOST UNSTABLE CAPE VALUES CONTINUE TO PLUMMET THIS EVENING...
HAVING DIMINISHED 400-600 J/KG WITHIN THE PAST 3 HOURS. WITH
VALUES OF 500-1000 J/KG STILL...CANNOT RULE OUT THE POSSIBILITY OF
ISOLATED THUNDERSTORMS FOR THE NEXT FEW HOURS. DESPITE THE
RELATIVELY LOW INSTABILITY...THERE IS DECENT EFFECTIVE BULK SHEAR
OF 30-40 KT TO MAXIMIZE IT. WE ARE NOT EXPECTING WIDESPREAD
SEVERE WEATHER THIS EVENING. RATHER THE MAIN THREATS WILL BE
FREQUENT LIGHTNING AND LOCALLY HEAVY RAINFALL. THOSE WITH PLANS
OUTDOORS THIS EVENING SHOULD GO INSIDE IMMEDIATELY IF
THUNDERSTORMS APPROACH YOUR PARTICULAR REGION. REMEMBER...IF YOU
CAN HEAR THUNDER...YOU ARE IN THE POTENTIAL LIGHTNING STRIKE ZONE.
OTHERWISE...ONLY MINOR TWEAKS NEEDED TO THE FORECAST THIS
EVENING. 31/20Z HRRR APPEARED TO HAVE A GOOD HANDLE ON THE TIMING
FOR CONVECTION...SO LEANED HEAVILY UPON IT FOR NEAR TERM RAINFALL
CHANCES.
PREVIOUS DISCUSSION...
CONVECTION FIRING ACROSS EASTERN PA AND NJ AND SE NY IN AXIS OF
SBCAPES 1500-2000 J/KG. CLOSER TO HOME...SBCAPES 500-1000 J/KG BUT
THERE ARE BREAKS DEVELOPING IN THE CLOUDS ACROSS SNE SO FURTHER
DESTABILIZATION IS LIKELY. HI-RES GUIDANCE CONTINUES TO POINT TO A
LATE SHOW WITH CONVECTION 21-00Z AS MID LEVEL SHORTWAVE MOVES IN
FROM THE WEST. PWATS ALREADY NEAR 2" AND EXPECTED TO PEAK AROUND
2.25" TOWARD 00Z SO HEAVY RAINFALL AND LOCALIZED FLASH FLOODING OF
URBAN AND POOR DRAINAGE AREAS IS THE PRIMARY THREAT. 0-6KM SHEAR
APPROACHING 40 KT IN THE WEST SO POTENTIAL EXISTS FOR A FEW STRONG
TO PERHAPS SEVERE TSTMS WITH DAMAGING WIND GUSTS ALSO A CONCERN IF
FURTHER DESTABILIZATION OCCURS.
MAIN FOCUS FOR CONVECTION WILL INITIALLY BE IN THE INTERIOR...BUT
EXPECT AT LEAST A FEW SHOWERS/TSTMS IN A WEAKENED STATE TO MAKE
IT TO THE COASTAL PLAIN LATER THIS EVENING AS SHORTWAVE MOVES
THROUGH. WHILE INSTABILITY WANES TONIGHT...THERE IS STILL
SOME SBCAPE AND HIGH KI VALUES TO SUPPORT CONVECTION. THE COLUMN
WILL WILL BEGIN TO DRY FROM THE N LATE TONIGHT ACROSS N ZONES.
AREAS OF STRATUS AND PATCHY FOG EXPECTED TO DEVELOP OVERNIGHT. IT
WILL BE A WARM AND HUMID NIGHT WITH MINS 65 TO AROUND 70 DEGREES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
MONDAY...
WARM AND HUMID AIRMASS CONTINUES ACROSS THE REGION WITH WEAK SFC
BOUNDARY/FRONT DRAPED ACROSS FAR N NEW ENG. PWATS DECREASE BELOW
1.5" ACROSS THE N BUT TROPICAL PLUME WITH PWATS NEAR 2" WILL
PERSIST IN THE SOUTH. AIRMASS DESTABILIZES AGAIN WITH SBCAPES
1000-1500 J/KG. SCT SHOWERS/TSTMS EXPECTED TO
REDEVELOP...ESPECIALLY ALONG AND SOUTH OF THE MASS PIKE WHERE
DEEPER MOISTURE IS PRESENT IN THE RIGHT ENTRANCE REGION OF THE
UPPER JET. 0-6KM SHEAR IS CONSIDERABLY WEAKER SO SEVERE WX NOT
ANTICIPATED. HEAVY RAINFALL IS THE MAIN THREAT IN HIGH PWAT
AIRMASS. TEMPS WILL REACH LOW TO MID 80S AGAIN...COOLER S COAST.
DEWPOINTS 70+ SO VERY HUMID.
MONDAY NIGHT...
COLUMN MOISTURE GRADUALLY DECREASES THROUGH THE NIGHT. SOME
LINGERING CONVECTION POSSIBLE IN THE EVENING ALONG THE S
COAST...OTHERWISE MAINLY DRY WEATHER. AREAS OF STRATUS AND FOG
WILL LIKELY REDEVELOP OVERNIGHT. ANOTHER HUMID NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
OVERVIEW AND MODEL PREFERENCES...
BROAD RIDGING REMAINS THE DOMINATE FEATURE ACROSS THE EASTERN USA
THROUGH MOST OF THIS FORECAST PERIOD. THIS IS MORE TYPICAL FOR THE
MIDDLE OF SUMMER RATHER THAN EARLY SEPTEMBER. EARLY IN THIS
PERIOD...THERE WILL BE A COUPLE OF FAST MOVING SYSTEMS IN THE BROAD
NORTHERN STREAM THAT WILL AFFECT OUR REGION. THIS STRONG RIDGE
FINALLY BECOMES ESTABLISHED AROUND MID WEEK ACROSS THE SOUTHERN
USA...WITH WARM BUT DRY CONDITIONS THROUGH THE END OF THIS WEEK.
SOME QUESTIONS AS TO WHEN THE RIDGING MAY BREAK DOWN...AS MODEL
SOLUTIONS LATE IN THE RUN TRY TO BREAK DOWN THE RIDGE WHILE BRINGING
A MID-LEVEL CUTOFF LOW ACROSS NORTH CENTRAL CANADA INTO NORTHERN
QUEBEC.
OVERALL...HAVE FAIRLY GOOD CONFIDENCE WITH MOST OF THIS FORECAST...
THOUGH SOME QUESTIONS WITH POSSIBLE CHANGES IN THE STEERING PATTERN
OVER THE NORTHERN TIER LATE THIS WEEK. HAVE LEANED TOWARD A BLEND OF
AVAILABLE GUIDANCE INTO FRIDAY...THEN PUSHED TOWARD A BLEND OF THE
ECENS AND GEFS MEANS WHICH SHOWED A SLOWER BREAKDOWN OF THE RIDGING
ACROSS THE REGION...WITH LOWER CONFIDENCE IN THE DETAILS OF
THIS FORECAST FOR THIS WEEKEND.
DAILIES...
TUESDAY...
ANOTHER FRONTAL SYSTEM STEADILY WORKS ITS WAY ACROSS OUT OF NY
STATE...THOUGH SOME TIMING ISSUES IN PLACE AMONGST THE OPERATIONAL
MODEL SUITE. KEPT CHANCE POPS ACROSS SOUTHWEST NH/WESTERN MA AROUND
MIDDAY. THEN PUSHED THIS FRONT....AND THE CORRESPONDING INCREASED
RAINFALL CHANCES...EAST THROUGH THE EVENING AND OVERNIGHT HOURS.
THIS TIMING MAY STILL BE TOO FAST.
WEDNESDAY...EXPECTING DRIER AIR TO SLOWLY ARRIVE DURING THE DAY ON
LIGHT WEST WINDS. HIGH PRESSURE WILL BUILD OUT OF THE APPALACHIANS.
TEMPERATURES WILL REMAIN WARM FOR THIS TIME OF YEAR...WITH A GENERAL
WEST WIND FLOW THROUGHOUT THE LAYER. COULD SEE SOME SHOWERS LINGER
ACROSS CAPE COD AND THE ISLANDS DURING THE EARLY MORNING HOURS.
THURSDAY AND FRIDAY...EXPECTING DRY AND MILD CONDITIONS CONTINUING
WITH DEWPOINTS FALLING INTO THE 50S...THOUGH AROUND 60 ALONG THE
IMMEDIATE COAST. CENTER OF HIGH PRESSURE SHIFTS OFFSHORE...RESULTING
AND LIGHT SOUTHWEST WINDS. THIS SHOULD MEAN SLIGHT ABOVE NORMAL
TEMPERATURES AWAY FROM THE IMMEDIATE COASTS.
SATURDAY AND SUNDAY...LOTS OF QUESTIONS DURING THIS TIMEFRAME...
MAINLY DUE TO TIMING ISSUES OF A COLD FRONT. KEPT MENTION OF CHANCE
POPS AS A COLD FRONT TRIES TO CROSS SOUTHERN NEW ENGLAND THIS
WEEKEND. LOW CONFIDENCE WITH THIS FEATURE. HIGH PRESSURE SHOULD
EVENTUALLY RETURN LATER SUNDAY.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH MONDAY NIGHT/...HIGH CONFIDENCE IN TRENDS BUT
LOWER CONFIDENCE IN PRECISE DETAILS AND TIMING.
TONIGHT...CONVECTION MAY LINGER TONIGHT AND MOVE ACROSS THE
COASTAL PLAIN BEFORE DIMINISHING. AREAS OF STRATUS AND PATCHY FOG
EXPECTED TO DEVELOP AND EXPAND ACROSS THIS REGION...BUT HIGHEST
PROBABILITY NEAR THE S COAST. EXACT TIMING UNCERTAIN FARTHER
INLAND...BUT SEVERAL SITES ALONG THE IMMEDIATE SOUTH COAST ALREADY
SOCKED IN.
MONDAY...MVFR/IFR CIGS/VSBYS MAY LINGER MOST OF THE DAY ALONG THE
SOUTH COAST...BUT IMPROVING TO VFR IN THE INTERIOR AND ESPECIALLY
FAR N AREAS AS DRIER AIR MOVES IN FROM THE N. SCT SHOWERS/TSTMS
EXPECTED TO DEVELOP WITH BRIEF MVFR/IFR POSSIBLE IN ANY TSTMS.
MONDAY NIGHT...AREAS OF IFR STRATUS AND FOG EXPECTED TO REDEVELOP
BUT UNCERTAINTY ON AREAL EXTENT. A FEW SHOWERS/TSTM MAY LINGER
INTO THE EVENING ALONG THE SOUTH COAST.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF REGARDING TRENDS BUT LOWER
CONFIDENCE ON PRECISE DETAILS AND TIMING.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF REGARDING TRENDS BUT LOWER
CONFIDENCE ON PRECISE DETAILS AND TIMING.
OUTLOOK...TUESDAY THROUGH FRIDAY...
TUESDAY...MODERATE CONFIDENCE.
MVFR-IFR VSBYS THROUGH AROUND 14Z IN PATCHY FOG...THEN BRIEF
PERIOD OF VFR. MAY SEE PERIODS OF MVFR IN SCT SHOWERS/TSTMS
ESPECIALLY INLAND DURING THE AFTERNOON/EVENING. PRECIP SHOULD
TAPER OFF AFTER MIDNIGHT. PATCHY FOG RETURNS AFTER 05Z-06Z WITH
MVFR-IFR VSBYS IN NORMALLY PRONE INLAND LOCATIONS.
WEDNESDAY THROUGH FRIDAY...MODERATE CONFIDENCE. EXPECTING MAINLY VFR
CONDITIONS AS HIGH PRESSURE BUILDS IN. LOCAL MVFR-IFR VSBYS AND CIGS
IN LATE NIGHT PATCHY FOG AND STRATUS. MAIN AREAS OF CONCERN WILL BE
THE TYPICALLY PRONE LOCATIONS ACROSS THE FAR INTERIOR /SOUTHWEST NH
AND NORTH CENTRAL AND WESTERN MA/.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
MODERATE CONFIDENCE THROUGH MONDAY NIGHT.
MODEST LOW LEVEL JET WILL HELP TO SUPPORT SOME SW GUSTS TO 25 KT
INTO THE EVENING ALONG THE SOUTH COASTAL NEARSHORE WATERS SO SCA
WILL CONTINUE. OVER THE OUTER WATERS...EXPECT WINDS TO REMAIN
BELOW SCA BUT BUILDING SEAS TO NEAR 5 FT SO SCA HERE AS WELL.
THE LOW LEVEL JET MOVES OFF THE COAST OVERNIGHT WITH DECREASING
WINDS. WINDS AND SEAS WILL BE BELOW SCA THRESHOLDS MONDAY INTO
MONDAY NIGHT.
A FEW SHOWERS/TSTMS POSSIBLE TONIGHT AND AGAIN MONDAY INTO MONDAY
EVENING. OTHERWISE...AREAS OF FOG WILL LIKELY REDUCE VSBYS LATER
TONIGHT INTO MONDAY...AND AGAIN MONDAY NIGHT.
OUTLOOK...TUESDAY THROUGH FRIDAY...
MODERATE CONFIDENCE. EXPECTING WINDS AND SEAS TO REMAIN BELOW SMALL
CRAFT CRITERIA THROUGH THIS PERIOD. MAY SEE SOME SOUTHWEST WIND
GUSTS UP TO 20 KT TUE NIGHT...BEFORE SHIFTING TO W-NW AND
DIMINISHING BY WED MORNING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
ANZ231>235-237.
SMALL CRAFT ADVISORY UNTIL 11 AM EDT MONDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...KJC
NEAR TERM...BELK/KJC
SHORT TERM...KJC
LONG TERM...BELK
AVIATION...BELK/KJC
MARINE...BELK/KJC
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
948 AM EDT SAT AUG 30 2014
.UPDATE...
12Z TBW SOUNDING DEPICTS A UNIFORMLY MOIST ATMOSPHERE WITH
PRECIPITABLE WATER CLOSE TO 2 INCHES. MORE IMPORTANTLY...THERE HAS
BEEN SOME COOLING IN THE 700 TO 500 MB LAYER SINCE THIS TIME
YESTERDAY WHICH WILL GIVE US STEEPER LAPSE RATES AND MORE ROBUST
UPDRAFTS IN THUNDERSTORMS. IT MAY TAKE A BIT LONGER THAN USUAL TO
GET THROUGH A WEAK WARM LAYER NEAR 800 MBS...BUT ONCE IT DOES
THERE IS NOTHING LEFT TO LIMIT RAIN POTENTIAL TODAY. MOST OF THE
CONVECTION ALLOWING MODELS...LOCAL AND NATIONALLY RUN...ARE
SHOWING A LATE AFTERNOON SEA BREEZE COLLISION ALONG THE COAST NEAR
THE I-75 CORRIDOR SOUTH OF THE NATURE COAST. A QUICK GLANCE AT THE
11Z HRRR IS IN EXCELLENT AGREEMENT WITH THE ABOVE SCENARIO...WHICH
LENDS CONFIDENCE TO MUCH HIGHER RAIN CHANCES ALONG THE COAST. THE
ONLY QUESTION IS IN TIMING. RIGHT NOW IT LOOKS LIKE MOST OF THE
RAIN WILL BE AFTER 5 PM...AND IT COULD EVEN BE CLOSER TO 7 OR 8
PM. THIS WILL DEPEND ON THE TIMING AND STRENGTH OF THE SEA BREEZES
ALONG BOTH THE EAST AND WEST COAST. WINDS THROUGH 15KFT ARE ALL
EASTERLY SO ANY EAST COAST SEA BREEZE ACTIVITY WILL DEFINITELY
MOVE TOWARD OUR SIDE OF THE STATE. THE QUESTION IS SPEED. OVERALL
STORM MOTION OUTSIDE OF SEA BREEZE AND OUTFLOW BOUNDARIES WILL BE
SLOW...LIKELY ONLY AROUND 5 MPH TOWARD THE NORTHWEST. MAIN THREAT
WILL BE LOCALLY HEAVY RAIN AND OF COURSE PLENTY OF LIGHTNING. IF
YOU HAVE OUTDOOR PLANS NEAR AND WEST OF THE I-75 CORRIDOR THIS
AFTERNOON AND EVENING...IT WOULD BE A GOOD IDEA TO KEEP AN EYE ON
THE WEATHER.
&&
.AVIATION...
BEST CHANCE FOR IFR/LIFR CONDITIONS WILL BE AT THE COASTAL
TERMINALS WHERE HIGHEST COVERAGE OF SEA BREEZE INDUCED STORMS IS
EXPECTED. TIMING MAY BE LATER THAN USUAL...POSSIBLY EVEN CLOSER TO
00Z. WILL CONTINUE TO HANDLE WITH VCTS UNTIL CONFIDENCE IN TIMING
INCREASES.
&&
.MARINE...
HIGH PRESSURE OVER THE ATLANTIC CONTINUES TO RIDGE WEST OVER THE
FLORIDA PENINSULA PRODUCING EAST SOUTHEAST WINDS LESS THAN 15 KNOTS
AND SEAS 2 TO 3 FEET FOR THE WEEKEND AND INTO NEXT WEEK. THE SEA
BREEZE WILL SET UP ALONG THE COASTLINE EACH DAY TURNING THE WINDS
TO AN ONSHORE FLOW OUT OF THE SOUTHWEST THROUGH NORTHWEST DIRECTION.
SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE EACH DAY OVER THE
COASTAL WATERS...PRODUCING GUSTY WINDS AND HIGHER SEAS IN THE
VICINITY OF THESE STORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 93 77 93 78 / 80 40 40 30
FMY 93 75 94 76 / 60 20 40 30
GIF 93 75 94 75 / 60 20 40 20
SRQ 92 76 94 75 / 80 30 40 30
BKV 94 74 94 73 / 70 30 40 20
SPG 93 80 93 79 / 70 40 40 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/AVIATION...JILLSON
MARINE...WYNN
DECISION SUPPORT...MROCZKA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
513 PM CDT SAT AUG 30 2014
.DISCUSSION...
221 PM CDT
SYNOPSIS...SCATTERED THUNDERSTORMS ARE POSSIBLE NW OF I-55 WHILE A
LINE OF STORMS WILL IMPACT AREAS ALONG AND EAST OF I-55 THROUGH THIS
EVENING. TOMORROW WILL BE DRY BUT UNSETTLED WEATHER RETURNS MONDAY
WITH MULTIPLE CHANCES FOR THUNDERSTORMS. SEVERE STORMS ARE POSSIBLE
MONDAY. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD WITH A
COUPLE DAYS GETTING INTO THE MID 80S.
THROUGH TONIGHT...
AN UPPER LEVEL TROUGH IS OVER THE UPPER MISSISSIPPI RIVER VALLEY AND
IT WILL PASS OVER THE REGION THROUGH THIS EVENING. A SURFACE LOW IS
OVER THE NORTHERN END OF LAKE MI WITH ITS COLD FRONT EXTENDING
THROUGH WI AND EASTERN IA. THE LOW WILL CONTINUE NE THROUGH THE
NIGHT.
HAVE MUCH HIGHER CONFIDENCE IN THE CONVECTIVE FORECAST TODAY
COMPARED TO YESTERDAY DUE TO CLEAR FORCING MECHANISMS. EXPECTING TO
HAVE TWO AREAS TO MONITOR. THE FIRST IS NORTHWEST OF I-55 WHERE
ISOLATED TO SCATTERED STORMS WILL CONTINUE TO FESTER THROUGH THIS
AFTERNOON AHEAD OF UPPER LEVEL WAVE AND COLD FRONT.
THE BIGGER CONCERN WILL BE ALONG AND SE OF I-55 WHERE A LINE OF
SHOWERS AND STORMS HAS ALREADY DEVELOPED. THE LATEST RAP ANALYSIS
SHOWS A NICE CORRIDOR OF MOISTURE CONVERGENCE WHERE THE CONVECTION
HAS FIRED. THE LATEST AMDAR SOUNDINGS ARE CAPLESS WITH 1000-1500
J/KG OF CAPE. HOWEVER...LAPSE RATES ARE POOR AND WIND SHEAR IS
MINIMAL AT BEST. THE AMDAR SOUNDINGS DO HAVE LOW LEVEL INVERTED
V/S AND THE RAP ANALYSIS HAS AROUND 1000 J/KG OF DOWNDRAFT CAPE.
THEREFORE NOT EXPECTING WIDESPREAD SEVERE WEATHER...BUT A STORM OR
TWO MAY PULSE UP AND PRODUCE SEVERE WINDS.
HEAVY DOWNPOURS ARE ALSO EXPECTED WITH PWAT VALUES OF 1.6-1.8
INCHES. BASED ON SHORT TERM GUIDANCE...THE AREA MOST CONCERNING IS
SOUTH OF A VALPARAISO IN TO GIBSON CITY IL LINE. STORMS WILL
CONTINUE TO DEVELOP AND MOVE OVER THIS REGION WITH AMPLE FORCING.
THEREFORE IF STORMS TRAIN OVER THE SAME AREA FOR AN EXTENDED PERIOD
OF TIME...FLASH FLOODING MAY OCCUR.
STORMS DIMINISH AND PUSH EAST OVERNIGHT WHILE HIGH PRESSURE SPREADS
OVER THE REGION. WINDS WILL DIMINISH AND FOG IS POSSIBLE.
SUNDAY...
SUNDAY LOOKS DRY WITH HIGH PRESSURE OVER THE REGION. WE WILL BE IN
THE NEXT LOW/S WARM SECTOR WITH 850MB TEMPS AROUND 18C. THEREFORE
RAISED HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. THE WEAK
PRESSURE GRADIENT WILL ALLOW A LAKE BREEZE TO FORM AND KEEP THE IL
LAKEFRONT AROUND 80. GUIDANCE HAS SLOWED THE NEXT LOW SO PUSHED
BACK POPS SUNDAY NIGHT.
JEE
MONDAY...
UPPER WAVE DIGGING TOWARDS THE INTERMOUNTAIN WEST THIS AFTERNOON
WILL LIFT ACROSS THE PLAINS INTO THE UPPER MIDWEST ON MONDAY WITH
ATTENDANT SURFACE LOW DEEPENING AS IT LIFTS ACROSS ONTARIO TO NEAR
JAMES BAY BY LATE MONDAY. A SURFACE FRONT WILL SLOWLY PUSH ACROSS
THE REGION MONDAY AND GUIDANCE HAS TRENDED TOWARDS A SLOWER SOLUTION
OVER THE LAST 24 HOURS. MODERATE TO STRONG INSTABILITY IS PROGGED TO
DEVELOP ALONG AND AHEAD OF THE FRONT WHERE THE GFS ADVERTISES A
CORRIDOR OF JUST OVER 2000 J/KG MLCAPE JUST TO THE WEST OF THE CWA
MONDAY AFTERNOON. THE BETTER CONVERGENCE ASSOCIATED WITH THE COLD
FRONT MAY ARRIVE JUST PAST THE MOST FAVORABLE DIURNAL TIMING IF
TIMING TRENDS HOLD TRUE...BUT THE RIGHT ENTRANCE REGION TO THE UPPER
JET IS PROGGED TO MOVE OVER THE AREA BY MID TO LATE IN THE EVENING
WITH DEEP LAYER SHEAR VALUES INCREASING TO AROUND 40 KT OR SO WHICH
WOULD BE SUFFICIENT FOR AN ORGANIZED SEVERE WEATHER THREAT...THOUGH
THIS THREAT SHOULD DIMINISH WEST TO EAST AS WE GET LATER INTO THE
OVERNIGHT HOURS AND THE BOUNDARY LAYER STABILIZES.
TUESDAY THROUGH THURSDAY...
A SECONDARY SHORTWAVE TROUGH IS PROGGED TO PUSH ACROSS THE REGION ON
TUESDAY BRINGING ADDITIONAL CHANCES FOR SHOWER AND THUNDERSTORMS
MAINLY ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE CWA WHERE THE
FRONTAL BOUNDARY MAY STILL SLOWLY BE MAKING A PUSH. MODERATE TO
STRONG HEIGHTS RISES QUICKLY BUILD IN BEHIND THIS FEATURE THOUGH AND
SHOULD RESULT IN A DRY WEATHER FOR MOST OF THE FORECAST AREA
TUESDAY. THE GFS IS PARTICULAR IS HOLDING ONTO SOME POPS NORTH OF
THE BOUNDARY WEDNESDAY INTO THURSDAY WHERE PERSISTENT WARM ADVECTION
WILL RESULT IN MID LEVEL ASCENT...THOUGH THE ECMWF REMAINS DRY THIS
PERIOD. WILL MAINTAIN SLIGHT CHANCE POPS IN THE MEANTIME.
FRIDAY THROUGH SATURDAY...
THERMAL RIDGE IS EXPECTED TO MOVE BACK OVERHEAD LATE IN THE WEEK
WITH H85 TEMPS PUSHING INTO THE LOW 20C RANGE WHICH WILL LEAD TO
ANOTHER WARMUP WITH TEMPS INTO THE UPPER 80S. ANOTHER SLOW MOVING
COLD FRONT WILL THEN SAG SOUTH ACROSS THE REGION BRINGING RENEWED
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* GUSTY WEST-SOUTHWEST WINDS DIMINISHING EARLY THIS EVENING.
* IFR CIGS AND VSBYS POSSIBLE OVERNIGHT INTO EARLY SUNDAY.
LENNING/IZZI
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* LOW-MEDIUM CONFIDENCE OF IFR CIGS AND VSBYS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
221 PM CDT
MODERATE SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS LAKE MICHIGAN
WHERE SOUTHWEST WINDS ARE GUSTING 20 TO 25 KTS WITH OCCASIONAL 30 KT
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NEARSHORE
WATERS THROUGH LATE THIS EVENING. THIS IS AHEAD OF LOW PRESSURE
CURRENTLY CENTERED NEAR GREEN BAY. THE LOW WILL DRAG A COLD FRONT
SOUTH ACROSS LAKE MICHIGAN TONIGHT TURNING WINDS TO THE NORTHWEST.
WINDS WILL ABATE BRIEFLY AS TRANSIENT HIGH PRESSURE PUSHES ACROSS
THE NORTHERN LAKES REGION...BUT BY MIDDAY SUNDAY WINDS ARE EXPECTED
TO BEGIN TO TURN SOUTHEAST AND START TO RAMP UP AGAIN AHEAD OF
ANOTHER AREA OF LOW PRESSURE. THIS NEXT WILL LOW LIFT FROM THE
NORTHERN PLAINS...DEEPENING AS IT HEADS TO HUDSON BAY MONDAY NIGHT
INTO TUESDAY. SOUTH WINDS ARE EXPECTED TO PEAK MONDAY OVER THE LAKE
WITH GUSTS SOLIDLY INTO THE 20 KT RANGE...APPROACHING 30 KT OVER THE
NORTH END OF THE LAKE. ANOTHER COLD FRONT WILL SAG SOUTH ACROSS LAKE
MICHIGAN MONDAY NIGHT.
DEUBELBEISS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 11 PM SATURDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
252 PM CDT SAT AUG 30 2014
.DISCUSSION...
221 PM CDT
SYNOPSIS...SCATTERED THUNDERSTORMS ARE POSSIBLE NW OF I-55 WHILE A
LINE OF STORMS WILL IMPACT AREAS ALONG AND EAST OF I-55 THROUGH THIS
EVENING. TOMORROW WILL BE DRY BUT UNSETTLED WEATHER RETURNS MONDAY
WITH MULTIPLE CHANCES FOR THUNDERSTORMS. SEVERE STORMS ARE POSSIBLE
MONDAY. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD WITH A
COUPLE DAYS GETTING INTO THE MID 80S.
THROUGH TONIGHT...
AN UPPER LEVEL TROUGH IS OVER THE UPPER MISSISSIPPI RIVER VALLEY AND
IT WILL PASS OVER THE REGION THROUGH THIS EVENING. A SURFACE LOW IS
OVER THE NORTHERN END OF LAKE MI WITH ITS COLD FRONT EXTENDING
THROUGH WI AND EASTERN IA. THE LOW WILL CONTINUE NE THROUGH THE
NIGHT.
HAVE MUCH HIGHER CONFIDENCE IN THE CONVECTIVE FORECAST TODAY
COMPARED TO YESTERDAY DUE TO CLEAR FORCING MECHANISMS. EXPECTING TO
HAVE TWO AREAS TO MONITOR. THE FIRST IS NORTHWEST OF I-55 WHERE
ISOLATED TO SCATTERED STORMS WILL CONTINUE TO FESTER THROUGH THIS
AFTERNOON AHEAD OF UPPER LEVEL WAVE AND COLD FRONT.
THE BIGGER CONCERN WILL BE ALONG AND SE OF I-55 WHERE A LINE OF
SHOWERS AND STORMS HAS ALREADY DEVELOPED. THE LATEST RAP ANALYSIS
SHOWS A NICE CORRIDOR OF MOISTURE CONVERGENCE WHERE THE CONVECTION
HAS FIRED. THE LATEST AMDAR SOUNDINGS ARE CAPLESS WITH 1000-1500
J/KG OF CAPE. HOWEVER...LAPSE RATES ARE POOR AND WIND SHEAR IS
MINIMAL AT BEST. THE AMDAR SOUNDINGS DO HAVE LOW LEVEL INVERTED
V/S AND THE RAP ANALYSIS HAS AROUND 1000 J/KG OF DOWNDRAFT CAPE.
THEREFORE NOT EXPECTING WIDESPREAD SEVERE WEATHER...BUT A STORM OR
TWO MAY PULSE UP AND PRODUCE SEVERE WINDS.
HEAVY DOWNPOURS ARE ALSO EXPECTED WITH PWAT VALUES OF 1.6-1.8
INCHES. BASED ON SHORT TERM GUIDANCE...THE AREA MOST CONCERNING IS
SOUTH OF A VALPARAISO IN TO GIBSON CITY IL LINE. STORMS WILL
CONTINUE TO DEVELOP AND MOVE OVER THIS REGION WITH AMPLE FORCING.
THEREFORE IF STORMS TRAIN OVER THE SAME AREA FOR AN EXTENDED PERIOD
OF TIME...FLASH FLOODING MAY OCCUR.
STORMS DIMINISH AND PUSH EAST OVERNIGHT WHILE HIGH PRESSURE SPREADS
OVER THE REGION. WINDS WILL DIMINISH AND FOG IS POSSIBLE.
SUNDAY...
SUNDAY LOOKS DRY WITH HIGH PRESSURE OVER THE REGION. WE WILL BE IN
THE NEXT LOW/S WARM SECTOR WITH 850MB TEMPS AROUND 18C. THEREFORE
RAISED HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. THE WEAK
PRESSURE GRADIENT WILL ALLOW A LAKE BREEZE TO FORM AND KEEP THE IL
LAKEFRONT AROUND 80. GUIDANCE HAS SLOWED THE NEXT LOW SO PUSHED
BACK POPS SUNDAY NIGHT.
JEE
MONDAY...
UPPER WAVE DIGGING TOWARDS THE INTERMOUNTAIN WEST THIS AFTERNOON
WILL LIFT ACROSS THE PLAINS INTO THE UPPER MIDWEST ON MONDAY WITH
ATTENDANT SURFACE LOW DEEPENING AS IT LIFTS ACROSS ONTARIO TO NEAR
JAMES BAY BY LATE MONDAY. A SURFACE FRONT WILL SLOWLY PUSH ACROSS
THE REGION MONDAY AND GUIDANCE HAS TRENDED TOWARDS A SLOWER SOLUTION
OVER THE LAST 24 HOURS. MODERATE TO STRONG INSTABILITY IS PROGGED TO
DEVELOP ALONG AND AHEAD OF THE FRONT WHERE THE GFS ADVERTISES A
CORRIDOR OF JUST OVER 2000 J/KG MLCAPE JUST TO THE WEST OF THE CWA
MONDAY AFTERNOON. THE BETTER CONVERGENCE ASSOCIATED WITH THE COLD
FRONT MAY ARRIVE JUST PAST THE MOST FAVORABLE DIURNAL TIMING IF
TIMING TRENDS HOLD TRUE...BUT THE RIGHT ENTRANCE REGION TO THE UPPER
JET IS PROGGED TO MOVE OVER THE AREA BY MID TO LATE IN THE EVENING
WITH DEEP LAYER SHEAR VALUES INCREASING TO AROUND 40 KT OR SO WHICH
WOULD BE SUFFICIENT FOR AN ORGANIZED SEVERE WEATHER THREAT...THOUGH
THIS THREAT SHOULD DIMINISH WEST TO EAST AS WE GET LATER INTO THE
OVERNIGHT HOURS AND THE BOUNDARY LAYER STABILIZES.
TUESDAY THROUGH THURSDAY...
A SECONDARY SHORTWAVE TROUGH IS PROGGED TO PUSH ACROSS THE REGION ON
TUESDAY BRINGING ADDITIONAL CHANCES FOR SHOWER AND THUNDERSTORMS
MAINLY ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE CWA WHERE THE
FRONTAL BOUNDARY MAY STILL SLOWLY BE MAKING A PUSH. MODERATE TO
STRONG HEIGHTS RISES QUICKLY BUILD IN BEHIND THIS FEATURE THOUGH AND
SHOULD RESULT IN A DRY WEATHER FOR MOST OF THE FORECAST AREA
TUESDAY. THE GFS IS PARTICULAR IS HOLDING ONTO SOME POPS NORTH OF
THE BOUNDARY WEDNESDAY INTO THURSDAY WHERE PERSISTENT WARM ADVECTION
WILL RESULT IN MID LEVEL ASCENT...THOUGH THE ECMWF REMAINS DRY THIS
PERIOD. WILL MAINTAIN SLIGHT CHANCE POPS IN THE MEANTIME.
FRIDAY THROUGH SATURDAY...
THERMAL RIDGE IS EXPECTED TO MOVE BACK OVERHEAD LATE IN THE WEEK
WITH H85 TEMPS PUSHING INTO THE LOW 20C RANGE WHICH WILL LEAD TO
ANOTHER WARMUP WITH TEMPS INTO THE UPPER 80S. ANOTHER SLOW MOVING
COLD FRONT WILL THEN SAG SOUTH ACROSS THE REGION BRINGING RENEWED
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* NORTHWEST EXTENT OF CONVECTION WORKING INTO MDW AREA...AND WITH
LESS LIKELIHOOD...POSSIBLY ORD AS WELL.
* GUSTY SOUTHWEST WINDS DIMINISHING THIS EVENING.
* MVFR CIGS/VSBYS AND STRONGER GUSTS NEAR STORMS.
* IFR CIGS AND VSBYS POSSIBLE OVERNIGHT INTO EARLY SUNDAY.
LENNING
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM TO LOW CONFIDENCE THAT ALL TSRA STAYS SOUTHEAST OF
ORD/MDW TERMINALS THIS AFTERNOON...BUT GREATER CONFIDENCE THAT
MORE WIDESPREAD ACTIVITY DOES STAY SOUTHEAST.
* MEDIUM CONFIDENCE OF IFR CIGS AND VSBYS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
221 PM CDT
MODERATE SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS LAKE MICHIGAN
WHERE SOUTHWEST WINDS ARE GUSTING 20 TO 25 KTS WITH OCCASIONAL 30 KT
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NEARSHORE
WATERS THROUGH LATE THIS EVENING. THIS IS AHEAD OF LOW PRESSURE
CURRENTLY CENTERED NEAR GREEN BAY. THE LOW WILL DRAG A COLD FRONT
SOUTH ACROSS LAKE MICHIGAN TONIGHT TURNING WINDS TO THE NORTHWEST.
WINDS WILL ABATE BRIEFLY AS TRANSIENT HIGH PRESSURE PUSHES ACROSS
THE NORTHERN LAKES REGION...BUT BY MIDDAY SUNDAY WINDS ARE EXPECTED
TO BEGIN TO TURN SOUTHEAST AND START TO RAMP UP AGAIN AHEAD OF
ANOTHER AREA OF LOW PRESSURE. THIS NEXT WILL LOW LIFT FROM THE
NORTHERN PLAINS...DEEPENING AS IT HEADS TO HUDSON BAY MONDAY NIGHT
INTO TUESDAY. SOUTH WINDS ARE EXPECTED TO PEAK MONDAY OVER THE LAKE
WITH GUSTS SOLIDLY INTO THE 20 KT RANGE...APPROACHING 30 KT OVER THE
NORTH END OF THE LAKE. ANOTHER COLD FRONT WILL SAG SOUTH ACROSS LAKE
MICHIGAN MONDAY NIGHT.
DEUBELBEISS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 11 PM SATURDAY.
&&
$$
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
223 PM CDT SAT AUG 30 2014
.DISCUSSION...
221 PM CDT
SYNOPSIS...SCATTERED THUNDERSTORMS ARE POSSIBLE NW OF I-55 WHILE A
LINE OF STORMS WILL IMPACT AREAS ALONG AND EAST OF I-55 THROUGH THIS
EVENING. TOMORROW WILL BE DRY BUT UNSETTLED WEATHER RETURNS MONDAY
WITH MULTIPLE CHANCES FOR THUNDERSTORMS. SEVERE STORMS ARE POSSIBLE
MONDAY. TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD WITH A
COUPLE DAYS GETTING INTO THE MID 80S.
THROUGH TONIGHT...
AN UPPER LEVEL TROUGH IS OVER THE UPPER MISSISSIPPI RIVER VALLEY AND
IT WILL PASS OVER THE REGION THROUGH THIS EVENING. A SURFACE LOW IS
OVER THE NORTHERN END OF LAKE MI WITH ITS COLD FRONT EXTENDING
THROUGH WI AND EASTERN IA. THE LOW WILL CONTINUE NE THROUGH THE
NIGHT.
HAVE MUCH HIGHER CONFIDENCE IN THE CONVECTIVE FORECAST TODAY
COMPARED TO YESTERDAY DUE TO CLEAR FORCING MECHANISMS. EXPECTING TO
HAVE TWO AREAS TO MONITOR. THE FIRST IS NORTHWEST OF I-55 WHERE
ISOLATED TO SCATTERED STORMS WILL CONTINUE TO FESTER THROUGH THIS
AFTERNOON AHEAD OF UPPER LEVEL WAVE AND COLD FRONT.
THE BIGGER CONCERN WILL BE ALONG AND SE OF I-55 WHERE A LINE OF
SHOWERS AND STORMS HAS ALREADY DEVELOPED. THE LATEST RAP ANALYSIS
SHOWS A NICE CORRIDOR OF MOISTURE CONVERGENCE WHERE THE CONVECTION
HAS FIRED. THE LATEST AMDAR SOUNDINGS ARE CAPLESS WITH 1000-1500
J/KG OF CAPE. HOWEVER...LAPSE RATES ARE POOR AND WIND SHEAR IS
MINIMAL AT BEST. THE AMDAR SOUNDINGS DO HAVE LOW LEVEL INVERTED
V/S AND THE RAP ANALYSIS HAS AROUND 1000 J/KG OF DOWNDRAFT CAPE.
THEREFORE NOT EXPECTING WIDESPREAD SEVERE WEATHER...BUT A STORM OR
TWO MAY PULSE UP AND PRODUCE SEVERE WINDS.
HEAVY DOWNPOURS ARE ALSO EXPECTED WITH PWAT VALUES OF 1.6-1.8
INCHES. BASED ON SHORT TERM GUIDANCE...THE AREA MOST CONCERNING IS
SOUTH OF A VALPARAISO IN TO GIBSON CITY IL LINE. STORMS WILL
CONTINUE TO DEVELOP AND MOVE OVER THIS REGION WITH AMPLE FORCING.
THEREFORE IF STORMS TRAIN OVER THE SAME AREA FOR AN EXTENDED PERIOD
OF TIME...FLASH FLOODING MAY OCCUR.
STORMS DIMINISH AND PUSH EAST OVERNIGHT WHILE HIGH PRESSURE SPREADS
OVER THE REGION. WINDS WILL DIMINISH AND FOG IS POSSIBLE.
SUNDAY...
SUNDAY LOOKS DRY WITH HIGH PRESSURE OVER THE REGION. WE WILL BE IN
THE NEXT LOW/S WARM SECTOR WITH 850MB TEMPS AROUND 18C. THEREFORE
RAISED HIGH TEMPS INTO THE MID 80S AWAY FROM THE LAKE. THE WEAK
PRESSURE GRADIENT WILL ALLOW A LAKE BREEZE TO FORM AND KEEP THE IL
LAKEFRONT AROUND 80. GUIDANCE HAS SLOWED THE NEXT LOW SO PUSHED
BACK POPS SUNDAY NIGHT.
JEE
MONDAY...
UPPER WAVE DIGGING TOWARDS THE INTERMOUNTAIN WEST THIS AFTERNOON
WILL LIFT ACROSS THE PLAINS INTO THE UPPER MIDWEST ON MONDAY WITH
ATTENDANT SURFACE LOW DEEPENING AS IT LIFTS ACROSS ONTARIO TO NEAR
JAMES BAY BY LATE MONDAY. A SURFACE FRONT WILL SLOWLY PUSH ACROSS
THE REGION MONDAY AND GUIDANCE HAS TRENDED TOWARDS A SLOWER SOLUTION
OVER THE LAST 24 HOURS. MODERATE TO STRONG INSTABILITY IS PROGGED TO
DEVELOP ALONG AND AHEAD OF THE FRONT WHERE THE GFS ADVERTISES A
CORRIDOR OF JUST OVER 2000 J/KG MLCAPE JUST TO THE WEST OF THE CWA
MONDAY AFTERNOON. THE BETTER CONVERGENCE ASSOCIATED WITH THE COLD
FRONT MAY ARRIVE JUST PAST THE MOST FAVORABLE DIURNAL TIMING IF
TIMING TRENDS HOLD TRUE...BUT THE RIGHT ENTRANCE REGION TO THE UPPER
JET IS PROGGED TO MOVE OVER THE AREA BY MID TO LATE IN THE EVENING
WITH DEEP LAYER SHEAR VALUES INCREASING TO AROUND 40 KT OR SO WHICH
WOULD BE SUFFICIENT FOR AN ORGANIZED SEVERE WEATHER THREAT...THOUGH
THIS THREAT SHOULD DIMINISH WEST TO EAST AS WE GET LATER INTO THE
OVERNIGHT HOURS AND THE BOUNDARY LAYER STABILIZES.
TUESDAY THROUGH THURSDAY...
A SECONDARY SHORTWAVE TROUGH IS PROGGED TO PUSH ACROSS THE REGION ON
TUESDAY BRINGING ADDITIONAL CHANCES FOR SHOWER AND THUNDERSTORMS
MAINLY ACROSS SOUTH/SOUTHEASTERN PORTIONS OF THE CWA WHERE THE
FRONTAL BOUNDARY MAY STILL SLOWLY BE MAKING A PUSH. MODERATE TO
STRONG HEIGHTS RISES QUICKLY BUILD IN BEHIND THIS FEATURE THOUGH AND
SHOULD RESULT IN A DRY WEATHER FOR MOST OF THE FORECAST AREA
TUESDAY. THE GFS IS PARTICULAR IS HOLDING ONTO SOME POPS NORTH OF
THE BOUNDARY WEDNESDAY INTO THURSDAY WHERE PERSISTENT WARM ADVECTION
WILL RESULT IN MID LEVEL ASCENT...THOUGH THE ECMWF REMAINS DRY THIS
PERIOD. WILL MAINTAIN SLIGHT CHANCE POPS IN THE MEANTIME.
FRIDAY THROUGH SATURDAY...
THERMAL RIDGE IS EXPECTED TO MOVE BACK OVERHEAD LATE IN THE WEEK
WITH H85 TEMPS PUSHING INTO THE LOW 20C RANGE WHICH WILL LEAD TO
ANOTHER WARMUP WITH TEMPS INTO THE UPPER 80S. ANOTHER SLOW MOVING
COLD FRONT WILL THEN SAG SOUTH ACROSS THE REGION BRINGING RENEWED
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DEUBELBEISS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* PRIMARY CONCERN IS TIMING...EXTENT...AND DURATION OF TSRA THIS
AFTERNOON.
LENNING
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE THAT WIDESPREAD TSRA REMAINS SOUTHEAST OF
TERMINALS...BUT LOW CONFIDENCE OF NO TSRA AT ALL.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM CONFIDENCE ON CEILING TRENDS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
221 PM CDT
MODERATE SOUTHWEST FLOW IS CURRENTLY IN PLACE ACROSS LAKE MICHIGAN
WHERE SOUTHWEST WINDS ARE GUSTING 20 TO 25 KTS WITH OCCASIONAL 30 KT
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE NEARSHORE
WATERS THROUGH LATE THIS EVENING. THIS IS AHEAD OF LOW PRESSURE
CURRENTLY CENTERED NEAR GREEN BAY. THE LOW WILL DRAG A COLD FRONT
SOUTH ACROSS LAKE MICHIGAN TONIGHT TURNING WINDS TO THE NORTHWEST.
WINDS WILL ABATE BRIEFLY AS TRANSIENT HIGH PRESSURE PUSHES ACROSS
THE NORTHERN LAKES REGION...BUT BY MIDDAY SUNDAY WINDS ARE EXPECTED
TO BEGIN TO TURN SOUTHEAST AND START TO RAMP UP AGAIN AHEAD OF
ANOTHER AREA OF LOW PRESSURE. THIS NEXT WILL LOW LIFT FROM THE
NORTHERN PLAINS...DEEPENING AS IT HEADS TO HUDSON BAY MONDAY NIGHT
INTO TUESDAY. SOUTH WINDS ARE EXPECTED TO PEAK MONDAY OVER THE LAKE
WITH GUSTS SOLIDLY INTO THE 20 KT RANGE...APPROACHING 30 KT OVER THE
NORTH END OF THE LAKE. ANOTHER COLD FRONT WILL SAG SOUTH ACROSS LAKE
MICHIGAN MONDAY NIGHT.
DEUBELBEISS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 11 PM SATURDAY.
&&
$$
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
1247 PM CDT SAT AUG 30 2014
.DISCUSSION...
1235 PM CDT
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE I-55 CORRIDOR. SO FAR THIS MORNING INTO
EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW CELLS
THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA.
LENNING
&&
.PREV DISCUSSION...
344 AM CDT
THE MAIN FORECAST CONCERNS WILL CENTER AROUND CONVECTIVE CHANCES AND
TIMING THROUGH THE PERIOD...ALONG WITH THE THREAT FOR STRONG TO
SEVERE CONVECTION...ESPECIALLY MONDAY.
WATER VAPOR IMAGERY EARLY THIS MORNING INDICATES TWO MID/UPPER LEVEL
DISTURBANCES OF INTEREST FOR TODAY AND TONIGHTS WEATHER. THE FIRST IS
LOCATED OVER IOWA AND INTO EXTREME NORTHERN MISSOURI...AND THIS IS
DRIVING AN AREA OF SHOWERS AND SOME EMBEDDED STORMS INTO WESTERN
ILLINOIS AT THIS HOUR. THIS WAVE IS EXPECTED TO LIFT NORTHEASTWARD
ACROSS WISCONSIN LATER THIS MORNING...AND AS IT DOES SO...A FEW
SCATTERED SHOWERS AND A THUNDERSTORM OR TWO CAN BE EXPECTED ACROSS
NORTHERN ILLINOIS. A SECOND DISTURBANCE IS CURRENTLY LOCATED ACROSS
THE EASTERN DAKOTAS SOUTHWARD INTO EASTERN NEBRASKA. THIS WAVE IS
EXPECTED TO SHIFT EASTWARD ACROSS WISCONSIN AND NORTHERN ILLINOIS
DURING THE AFTERNOON TODAY. THESE TWO DISTURBANCES WILL HELP INDUCE
A UPPER LEVEL 60+ KT SPEED MAX ACROSS THE LOWER GREAT LAKES
REGION...ESSENTIALLY SETTING UP PORTIONS OF MY AREA TO LINE UP WITHIN
THE FAVORABLE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MAX THIS
AFTERNOON AND INTO TONIGHT. THIS SHOULD HELP TO DRIVE AN AREA OF
SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF THE AREA ALONG AND
AHEAD OF AN APPROACHING SURFACE COLD FRONT.
IT APPEARS THE BEST CHANCES FOR MORE ROBUST CONVECTIVE DEVELOPMENT
WILL BEGIN BY EARLY TO MID AFTERNOON OVER OR JUST TO THE SOUTH AND
EAST OF THE CHICAGO AREA. HIRES CONVECTIVE ALLOWING MODELS CONTINUE
TO INDICATE THE FAVORABLE LOCATIONS FOR AFTERNOON CONVECTIVE
ACTIVITY WILL PRIMARILY BE ALONG AND SOUTH OF A CHICAGO TO OTTAWA
LINE. ALTHOUGH MORNING SHOWERS AND CLOUD COVER COULD HAMPER
INSOLATION SOME ACROSS THE AREA...IT APPEARS THAT WITH DEW POINTS IN
THE LOWER 70S...MLCAPES SHOULD END UP AROUND 1500 J/KG...ESPECIALLY
ACROSS THE SOUTHEASTERN HALF OF MY AREA. THE INCREASING MID AND AN
UPPER LEVEL WIND FIELD ALSO LOOKS TO INCREASE THE DEEP LAYER SHEAR
UP TO 25 TO 30 KT...WHICH COULD SUPPORT A FEW STRONGER STORMS
CAPABLE OF STRONG WIND GUSTS. THESE STORMS WILL ALSO LIKELY PRODUCE
SOME TORRENTIAL DOWNPOURS GIVEN THE HIGH PWAT AIRMASS IN PLACE.
STORM MOTIONS OF 30 TO 40 KT SHOULD LIMIT THE RESIDENCE TIME OF
THESE STORMS OVER A GIVEN AREA...MAKING EXTREME RAINFALL AMOUNTS IN
A GIVEN AREA UNLIKELY. THESE STORMS LOOK TO LINGER INTO THE
EVENING HOURS TONIGHT...ESPECIALLY ACROSS MY FAR SOUTHEASTERN
COUNTIES IN NORTHWESTERN INDIANA AND EAST CENTRAL ILLINOIS.
SUNDAY STILL APPEARS TO BE THE PICK DAY OF THE WEEKEND...WITH A
TEMPORARY BREAK FROM THE SHOWER AND THUNDERSTORM ACTIVITY...WHICH
WILL RETURN BY LABOR DAY. THE WEATHER PATTERN WILL BECOME ACTIVE
AGAIN EARLY NEXT WEEK AS A SIGNIFICANT UPPER LEVEL DISTURBANCE AND
ASSOCIATED SPEED MAX...EMANATING FROM THE NORTHEASTERN
PACIFIC...DIGS ACROSS THE NORTHERN CONUS. THIS LOOKS TO SUPPORT A
SURFACE LOW...WHICH SHOULD SHIFT NORTHEASTWARD ACROSS THE UPPER
MIDWEST AND INTO ONTARIO BY MONDAY. CONVECTIVE ACTIVITY...POSSIBLY
STRONG TO SEVERE WILL BE FAVORED LATE SUNDAY FROM KANSAS
NORTHEASTWARD ACROSS ACROSS IOWA AND MINNESOTA AHEAD OF AN
APPROACHING COLD FRONT. THIS COLD FRONT IS EXPECTED TO MOVE INTO
NORTHERN ILLINOIS DURING THE DAY MONDAY...AND IT APPEARS THE DIURNAL
TIMING OF THIS FRONT...AND UPPER LEVEL SYSTEM...COULD BE FAVORABLE
FOR STRONG TO SEVERE CONVECTION ACROSS THE AREA MONDAY AFTERNOON AND
EVENING...ESPECIALLY CONSIDERING THE DEEP LAYER SHEAR IS EXPECTED TO
BE MORE THAN ADEQUATE FOR ORGANIZED STRONG CONVECTION.
UNCERTAINTY INCREASES A BIT LATER MONDAY NIGHT INTO TUESDAY...AS THE
VARIOUS MODEL GUIDANCE ARE IN DISAGREEMENT IN HOW FAST THE SURFACE
COLD FRONT WILL PUSH ACROSS MY ENTIRE AREA. THE ECMWF IS SUGGESTING
A SLOWER MOVEMENT OF THE FRONTAL BOUNDARY INTO TUESDAY AS IT
SUGGESTS THAT ANOTHER MID LEVEL IMPULSE WILL SHIFT OVER THE AREA
LEADING TO THE DEVELOPMENT OF A SECONDARY SURFACE LOW OVER THE AREA.
IF THIS SOLUTION WERE TO PAN OUT...IT COULD SET THE STAGE FOR SOME
VERY HEAVY RAINFALL AMOUNTS ACROSS PORTIONS OF THE AREA INTO TUESDAY
MORNING.
DURING THE MID TO LATER PORTION OF THE WEEK IT APPEARS THINGS WILL
BE ON A WARMING TREND...ESPECIALLY BY THURSDAY AS MID LEVEL HEIGHTS
BUILD SUBSTANTIALLY ACROSS THE AREA. THIS COULD LEAD TO A RUN AT
UPPER 80 TO LOWER 90 TEMPERATURES FOR THURSDAY. I CONTINUED WITH
SLIGHT CHANCE POPS DURING THE LATER PERIOD...MAINLY DUE TO
UNCERTAINTIES ON WHETHER OR NOT ANY SMALL SCALE DISTURBANCES WILL TRY
TO SPARK OFF CONVECTION OVER THE AREA. HOWEVER...WITH THE BUILDING
HEIGHTS AND WARMING TEMPERATURES ALOFT...THE AREA COULD END UP
CAPPED TO CONVECTIVE DEVELOPMENT ON WEDNESDAY AND THURSDAY.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* PRIMARY CONCERN IS TIMING...EXTENT...AND DURATION OF TSRA THIS
AFTERNOON.
LENNING
//DISCUSSION...UPDATED 18Z...
MODEL FORECAST DATA...SATELLITE IMAGERY...ACARS AIRCRAFT
SOUNDINGS...AND RECENT RADAR TRENDS ALL SUPPORT THE IDEA OF
INCREASED CONVECTIVE DEVELOPMENT THIS AFTERNOON...PRIMARILY
FOCUSED SOUTHEAST OF THE ORD/MDW TERMINALS. SO FAR THIS MORNING
INTO EARLY AFTERNOON THERE HAS BEEN LITTLE LIGHTNING WITH THE FEW
CELLS THAT HAVE DEVELOPED...BUT WOULD NOT BE SURPRISED TO SEE MORE
ACTIVE CONVECTION AS WE APPROACH PEAK DIURNAL HEATING. LESS
PRONOUNCED MOISTURE TRANSPORT NORTHWEST OF THIS CORRIDOR ALONG
WITH RELATIVELY WARM AIR ALOFT ARE THE FACTORS CONTRIBUTING TO
LESS CONFIDENCE OF WIDESPREAD AFTERNOON CONVECTION ACROSS THE
NORTHWEST HALF OF THE AREA...INCLUDING ORD/MDW AS WELL AS DPA AND
RFD. THE GYY TERMINAL WOULD BE ALONG THE NORTHWEST EDGE OF THE
AREA EXPECTED TO HAVE THE MORE EXTENSIVE COVERAGE.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE THAT WIDESPREAD TSRA REMAINS SOUTHEAST OF
TERMINALS...BUT LOW CONFIDENCE OF NO TSRA AT ALL.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* MEDIUM CONFIDENCE ON CEILING TRENDS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
300 AM CDT
A PERIOD OF ACTIVE WEATHER IS SETTING UP FOR LAKE MICHIGAN FOR
THE NEXT SEVERAL DAYS. A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL
TRACK ACROSS THE UPPER GREAT LAKES REGION INTO CANADA DRAGGING
WEAK COLD FRONTS ACROSS THE LAKE. MODERATE SOUTH TO SOUTHWESTERLY
WINDS WILL PERSIST ACROSS THE LAKE THROUGH MUCH OF SATURDAY UNTIL
THE FIRST OF THE COLD FRONTS SWEEPS ACROSS THE LAKE LATE THIS
AFTERNOON AND THIS EVENING...TURNING WINDS TO NORTHWESTERLY
TONIGHT. A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD IN
BEHIND THE FRONT...ALLOWING WINDS TO DROP OFF AND BECOME MORE
VARIABLE IN DIRECTION EARLY SUNDAY. BY SUNDAY AFTERNOON...ANOTHER
DEVELOPING LOW OVER THE NORTHERN PLAINS WILL LEAD TO STRENGTHENING
SOUTHERLY WINDS FOR MONDAY AND MONDAY EVENING...UP TO 25 KT...BUT
THE NEXT FRONT WILL CROSS THE LAKE MONDAY NIGHT. THIS FRONTAL
PASSAGE WILL NOT BE AS ABRUPT AS THE FIRST WITH WINDS ONLY VEERING
SOUTHWESTERLY. WINDS SHOULD INCREASE AGAIN TO UP TO 25KT
IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE MONDAY NIGHT...BUT SHOULD
THEN WEAKEN SLIGHTLY INTO MIDWEEK WHILE REMAINING GENERALLY
SOUTHWESTERLY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1236 PM CDT Sat Aug 30 2014
.UPDATE...
ISSUED AT 1052 AM CDT SAT AUG 30 2014
Much of central Illinois remains convection-free this morning,
except for the far SE KILX CWA south of I-70 where showers and
thunderstorms are ongoing. 15z/10am visible satellite imagery is
beginning to show an enhanced band of Cu along the Illinois River
that will eventually become a broken line of thunderstorms this
afternoon. HRRR shows storms developing along the I-55 corridor
after 20z, so have adjusted PoPs accordingly. Have focused likely
PoPs along/east of I-55 by mid-afternoon into the early evening
hours. Further west, will only carry low chances along/west of the
Illinois River this afternoon, then dry by evening.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lift associated with an upper level shortwave trough over eastern
Iowa moving east-northeastward this morning is providing a focus for
a line of convection moving into western Illinois while a weaker
line of showers roughly along I-57 continues in eastern Illinois.
Cold front associated with the trough to our west is expected to
move to around to IA/IL border and stall out as the upper level
shortwave lifts northeastward bringing a continued focus for
precipitation for much of the next 24 hours. Rich moisture of close
to 2 inches will continue to stream into southeast Illinois to bring
the best chances for precipitation in that region. Tonight, as the
main trough shifts eastward, drier air continues to push eastward
allowing drier conditions to spread eastward into Illinois. As a
result, have pops trending downward overnight. Temperatures will be
down slightly today and tonight.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lingered a chance of showers and thunderstorms over southeast IL
Sunday where more clouds will be over eastern/se IL. Best chances of
convection will be southeast of Ohio river across KY where short
wave energy will be. Highs in the low to mid 80s Sunday (warmest
over western areas) and humid with dewpoints mostly in the lower
70s. Dry conditions across area Sunday evening then have chance of
showers and thunderstorms returning to areas nw of I-55 overnight
Sunday night. This due to approaching strong upper level trof over
Pacific Northwest that brings a cold front se through IL Monday
night. Quite warm and humid again on Monday with highs in the 80s
and dewpoints in the lower to middle 70s. Chances of showers and
thunderstorms increase from nw to se during the day Monday with
highest chances Monday afternoon/evening, gradually shifting chances
se overnight Monday night. SPC has much of central IL in a slight
chance of severe storms Monday afternoon/evening for damaging winds
and large hail. Surface to 6km bulk shear around 40 kts and CAPES
2-3K J/Kg supports this risk of severe storms from I-70 nw.
Upper level flow to become zonal by middle of next week and frontal
boundary likely not to get too far south of IL. Thus will continue
chances of showers and thunderstorms Tue with best chances (40-50%)
in southeast IL closer to frontal boundary while slight chances nw
of IL river. Just slight chances by Wed-Thu night and quite warm and
humid with highs in the mid to upper 80s and even approaching
lower 90s over southern areas Thu and Friday. This is due to
upper level ridge of 593 dm 500 mb high building over KY/TN. Next
frontal boundary to press se toward IL later Friday into Saturday
of next week increasing chances of showers and thunderstorms followed
by cooler weather next weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1236 PM CDT SAT AUG 30 2014
Robust Cu-field continues to develop between the Illinois River
and I-55 early this afternoon: however, 1728z radar imagery
remains clear. As instability slowly increases, am expecting
scattered thunderstorms to develop along this corridor after
19/20z. Given timing and areal coverage uncertainties, have
included VCTS at all terminals beginning at 18z. As the afternoon
progresses, think main area of concern will shift east of the
Illinois River Valley, so have dropped VCTS at KPIA after 22z.
Further east, will maintain thunder mention through 05z, allowing
plenty of time for any diurnally driven storms to dissipate after
sunset. Once convection ends, skies will partially clear and winds
will become quite light overnight. Forecast soundings and numeric
guidance both suggest patchy fog, particularly across the western
KILX CWA where winds will be lightest. As a result, have included
reduced visbys down to 2-3sm between 09z and 13z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1118 AM CDT SAT AUG 30 2014
.DISCUSSION...
344 AM CDT
THE MAIN FORECAST CONCERNS WILL CENTER AROUND CONVECTIVE CHANCES AND
TIMING THROUGH THE PERIOD...ALONG WITH THE THREAT FOR STRONG TO
SEVERE CONVECTION...ESPECIALLY MONDAY.
WATER VAPOR IMAGERY EARLY THIS MORNING INDICATES TWO MID/UPPER LEVEL
DISTURBANCES OF INTEREST FOR TODAY AND TONIGHTS WEATHER. THE FIRST IS
LOCATED OVER IOWA AND INTO EXTREME NORTHERN MISSOURI...AND THIS IS
DRIVING AN AREA OF SHOWERS AND SOME EMBEDDED STORMS INTO WESTERN
ILLINOIS AT THIS HOUR. THIS WAVE IS EXPECTED TO LIFT NORTHEASTWARD
ACROSS WISCONSIN LATER THIS MORNING...AND AS IT DOES SO...A FEW
SCATTERED SHOWERS AND A THUNDERSTORM OR TWO CAN BE EXPECTED ACROSS
NORTHERN ILLINOIS. A SECOND DISTURBANCE IS CURRENTLY LOCATED ACROSS
THE EASTERN DAKOTAS SOUTHWARD INTO EASTERN NEBRASKA. THIS WAVE IS
EXPECTED TO SHIFT EASTWARD ACROSS WISCONSIN AND NORTHERN ILLINOIS
DURING THE AFTERNOON TODAY. THESE TWO DISTURBANCES WILL HELP INDUCE
A UPPER LEVEL 60+ KT SPEED MAX ACROSS THE LOWER GREAT LAKES
REGION...ESSENTIALLY SETTING UP PORTIONS OF MY AREA TO LINE UP WITHIN
THE FAVORABLE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MAX THIS
AFTERNOON AND INTO TONIGHT. THIS SHOULD HELP TO DRIVE AN AREA OF
SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF THE AREA ALONG AND
AHEAD OF AN APPROACHING SURFACE COLD FRONT.
IT APPEARS THE BEST CHANCES FOR MORE ROBUST CONVECTIVE DEVELOPMENT
WILL BEGIN BY EARLY TO MID AFTERNOON OVER OR JUST TO THE SOUTH AND
EAST OF THE CHICAGO AREA. HIRES CONVECTIVE ALLOWING MODELS CONTINUE
TO INDICATE THE FAVORABLE LOCATIONS FOR AFTERNOON CONVECTIVE
ACTIVITY WILL PRIMARILY BE ALONG AND SOUTH OF A CHICAGO TO OTTAWA
LINE. ALTHOUGH MORNING SHOWERS AND CLOUD COVER COULD HAMPER
INSOLATION SOME ACROSS THE AREA...IT APPEARS THAT WITH DEW POINTS IN
THE LOWER 70S...MLCAPES SHOULD END UP AROUND 1500 J/KG...ESPECIALLY
ACROSS THE SOUTHEASTERN HALF OF MY AREA. THE INCREASING MID AND AN
UPPER LEVEL WIND FIELD ALSO LOOKS TO INCREASE THE DEEP LAYER SHEAR
UP TO 25 TO 30 KT...WHICH COULD SUPPORT A FEW STRONGER STORMS
CAPABLE OF STRONG WIND GUSTS. THESE STORMS WILL ALSO LIKELY PRODUCE
SOME TORRENTIAL DOWNPOURS GIVEN THE HIGH PWAT AIRMASS IN PLACE.
STORM MOTIONS OF 30 TO 40 KT SHOULD LIMIT THE RESIDENCE TIME OF
THESE STORMS OVER A GIVEN AREA...MAKING EXTREME RAINFALL AMOUNTS IN
A GIVEN AREA UNLIKELY. THESE STORMS LOOK TO LINGER INTO THE
EVENING HOURS TONIGHT...ESPECIALLY ACROSS MY FAR SOUTHEASTERN
COUNTIES IN NORTHWESTERN INDIANA AND EAST CENTRAL ILLINOIS.
SUNDAY STILL APPEARS TO BE THE PICK DAY OF THE WEEKEND...WITH A
TEMPORARY BREAK FROM THE SHOWER AND THUNDERSTORM ACTIVITY...WHICH
WILL RETURN BY LABOR DAY. THE WEATHER PATTERN WILL BECOME ACTIVE
AGAIN EARLY NEXT WEEK AS A SIGNIFICANT UPPER LEVEL DISTURBANCE AND
ASSOCIATED SPEED MAX...EMANATING FROM THE NORTHEASTERN
PACIFIC...DIGS ACROSS THE NORTHERN CONUS. THIS LOOKS TO SUPPORT A
SURFACE LOW...WHICH SHOULD SHIFT NORTHEASTWARD ACROSS THE UPPER
MIDWEST AND INTO ONTARIO BY MONDAY. CONVECTIVE ACTIVITY...POSSIBLY
STRONG TO SEVERE WILL BE FAVORED LATE SUNDAY FROM KANSAS
NORTHEASTWARD ACROSS ACROSS IOWA AND MINNESOTA AHEAD OF AN
APPROACHING COLD FRONT. THIS COLD FRONT IS EXPECTED TO MOVE INTO
NORTHERN ILLINOIS DURING THE DAY MONDAY...AND IT APPEARS THE DIURNAL
TIMING OF THIS FRONT...AND UPPER LEVEL SYSTEM...COULD BE FAVORABLE
FOR STRONG TO SEVERE CONVECTION ACROSS THE AREA MONDAY AFTERNOON AND
EVENING...ESPECIALLY CONSIDERING THE DEEP LAYER SHEAR IS EXPECTED TO
BE MORE THAN ADEQUATE FOR ORGANIZED STRONG CONVECTION.
UNCERTAINTY INCREASES A BIT LATER MONDAY NIGHT INTO TUESDAY...AS THE
VARIOUS MODEL GUIDANCE ARE IN DISAGREEMENT IN HOW FAST THE SURFACE
COLD FRONT WILL PUSH ACROSS MY ENTIRE AREA. THE ECMWF IS SUGGESTING
A SLOWER MOVEMENT OF THE FRONTAL BOUNDARY INTO TUESDAY AS IT
SUGGESTS THAT ANOTHER MID LEVEL IMPULSE WILL SHIFT OVER THE AREA
LEADING TO THE DEVELOPMENT OF A SECONDARY SURFACE LOW OVER THE AREA.
IF THIS SOLUTION WERE TO PAN OUT...IT COULD SET THE STAGE FOR SOME
VERY HEAVY RAINFALL AMOUNTS ACROSS PORTIONS OF THE AREA INTO TUESDAY
MORNING.
DURING THE MID TO LATER PORTION OF THE WEEK IT APPEARS THINGS WILL
BE ON A WARMING TREND...ESPECIALLY BY THURSDAY AS MID LEVEL HEIGHTS
BUILD SUBSTANTIALLY ACROSS THE AREA. THIS COULD LEAD TO A RUN AT
UPPER 80 TO LOWER 90 TEMPERATURES FOR THURSDAY. I CONTINUED WITH
SLIGHT CHANCE POPS DURING THE LATER PERIOD...MAINLY DUE TO
UNCERTAINTIES ON WHETHER OR NOT ANY SMALL SCALE DISTURBANCES WILL TRY
TO SPARK OFF CONVECTION OVER THE AREA. HOWEVER...WITH THE BUILDING
HEIGHTS AND WARMING TEMPERATURES ALOFT...THE AREA COULD END UP
CAPPED TO CONVECTIVE DEVELOPMENT ON WEDNESDAY AND THURSDAY.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* STILL CONCERNED ABOUT LOCAL TSRA TRENDS BUT ALSO NOT CONFIDENT
ENOUGH IN TIMING OR LOCATION OR DURATION TO INCLUDE IN TAF.
SHOWERS FORMING OVER WI ARE LIFTING NORTHEAST AND SO FAR ARE NOT
PRODUCING LIGHTNING.
LENNING
//DISCUSSION...UPDATED 12Z...
SCT SHRA AND ISOLD TSRA CONTINUE THROUGH THE DAY TODAY AS THE AREA
REMAINS ENTRENCHED IN A WARM/MOIST AIRMASS. A WEAK COLD FRONT IS
EXPECTED TO MOVE ACROSS THE AREA TODAY IN ASSOCIATION WITH A
STRONGER UPPER LEVEL TROUGH. THE UPPER TROUGH AND SFC FRONT SHOULD
PROVIDE SOME FOCUS FOR MORE THUNDERSTORM ACTIVITY. HOWEVER...THE
TIMING OF THE FRONT WILL PLAY A SIGNIFICANT ROLE IN THE TS
COVERAGE AS IT SHOULD MOVE NRN IL BY LATE MORNING...AT A TIME
BEFORE MAX DIURNAL WARMING. THE HIGH RESOLUTION MODEL GUIDANCE
SUGGESTS THAT TS COVERAGE SHOULD INCREASE AS THE FRONT MOVES
THROUGH ECNTRL IL AND NWRN IN DURG THE EARLY AFTERNOON HOURS.
HAVE OPTED TO GO WITH THE TEMPO GROUP FOR TS FOR THE MOST
FAVORABLE TIME FOR CONVECTIVE ACTIVITY OVER THE AREA...BUT THIS IS
STILL A LOW CONFIDENCE FORECAST.
WINDS SHOULD BECOME MORE SWLY WITH GUSTS TO 15-20KT FOR THE LATE
MORNING INTO EARLY EVENING AS SOME BREAKS IN THE OVERCAST ALLOWS
FOR SOME MIXING DOWN OF STRONGER WINDS ALOFT. WINDS SHOULD DROP
OFF AND BECOME LGT/VRBL OVERNIGHT AS HIGH PRESSURE SPREADS ACROSS
THE AREA. WITH CLEARING SKIES...LIGHT WINDS AND AMPLE RESIDUAL LOW
LEVEL MOISTURE IN PLACE...THERE IS AN INCREASING CHANCE FOR FOG
AND STATUS TO DEVELOP DURG THE LATE NIGHT HOURS TONIGHT.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* LOW TO MEDIUM CONFIDENCE OF TSRA STAYING OUT OF TERMINALS.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS EXCEPT NEAR STORMS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR.
MONDAY...PERIODS OF TSRA LIKELY.
TUESDAY...SLIGHT CHANCE TSRA EARLY.
WEDNESDAY...SLIGHT CHANCE TSRA OVERNIGHT.
THURSDAY AND FRIDAY...CHANCE TSRA.
KREIN
&&
.MARINE...
300 AM CDT
A PERIOD OF ACTIVE WEATHER IS SETTING UP FOR LAKE MICHIGAN FOR
THE NEXT SEVERAL DAYS. A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL
TRACK ACROSS THE UPPER GREAT LAKES REGION INTO CANADA DRAGGING
WEAK COLD FRONTS ACROSS THE LAKE. MODERATE SOUTH TO SOUTHWESTERLY
WINDS WILL PERSIST ACROSS THE LAKE THROUGH MUCH OF SATURDAY UNTIL
THE FIRST OF THE COLD FRONTS SWEEPS ACROSS THE LAKE LATE THIS
AFTERNOON AND THIS EVENING...TURNING WINDS TO NORTHWESTERLY
TONIGHT. A WEAK RIDGE OF HIGH PRESSURE WILL BRIEFLY BUILD IN
BEHIND THE FRONT...ALLOWING WINDS TO DROP OFF AND BECOME MORE
VARIABLE IN DIRECTION EARLY SUNDAY. BY SUNDAY AFTERNOON...ANOTHER
DEVELOPING LOW OVER THE NORTHERN PLAINS WILL LEAD TO STRENGTHENING
SOUTHERLY WINDS FOR MONDAY AND MONDAY EVENING...UP TO 25 KT...BUT
THE NEXT FRONT WILL CROSS THE LAKE MONDAY NIGHT. THIS FRONTAL
PASSAGE WILL NOT BE AS ABRUPT AS THE FIRST WITH WINDS ONLY VEERING
SOUTHWESTERLY. WINDS SHOULD INCREASE AGAIN TO UP TO 25KT
IMMEDIATELY FOLLOWING THE FRONTAL PASSAGE MONDAY NIGHT...BUT SHOULD
THEN WEAKEN SLIGHTLY INTO MIDWEEK WHILE REMAINING GENERALLY
SOUTHWESTERLY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1052 AM CDT Sat Aug 30 2014
.UPDATE...
ISSUED AT 1052 AM CDT SAT AUG 30 2014
Much of central Illinois remains convection-free this morning,
except for the far SE KILX CWA south of I-70 where showers and
thunderstorms are ongoing. 15z/10am visible satellite imagery is
beginning to show an enhanced band of Cu along the Illinois River
that will eventually become a broken line of thunderstorms this
afternoon. HRRR shows storms developing along the I-55 corridor
after 20z, so have adjusted PoPs accordingly. Have focused likely
PoPs along/east of I-55 by mid-afternoon into the early evening
hours. Further west, will only carry low chances along/west of the
Illinois River this afternoon, then dry by evening.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lift associated with an upper level shortwave trough over eastern
Iowa moving east-northeastward this morning is providing a focus for
a line of convection moving into western Illinois while a weaker
line of showers roughly along I-57 continues in eastern Illinois.
Cold front associated with the trough to our west is expected to
move to around to IA/IL border and stall out as the upper level
shortwave lifts northeastward bringing a continued focus for
precipitation for much of the next 24 hours. Rich moisture of close
to 2 inches will continue to stream into southeast Illinois to bring
the best chances for precipitation in that region. Tonight, as the
main trough shifts eastward, drier air continues to push eastward
allowing drier conditions to spread eastward into Illinois. As a
result, have pops trending downward overnight. Temperatures will be
down slightly today and tonight.
&&
.LONG TERM...(Sunday through Friday)
ISSUED AT 401 AM CDT SAT AUG 30 2014
Lingered a chance of showers and thunderstorms over southeast IL
Sunday where more clouds will be over eastern/se IL. Best chances of
convection will be southeast of Ohio river across KY where short
wave energy will be. Highs in the low to mid 80s Sunday (warmest
over western areas) and humid with dewpoints mostly in the lower
70s. Dry conditions across area Sunday evening then have chance of
showers and thunderstorms returning to areas nw of I-55 overnight
Sunday night. This due to approaching strong upper level trof over
Pacific Northwest that brings a cold front se through IL Monday
night. Quite warm and humid again on Monday with highs in the 80s
and dewpoints in the lower to middle 70s. Chances of showers and
thunderstorms increase from nw to se during the day Monday with
highest chances Monday afternoon/evening, gradually shifting chances
se overnight Monday night. SPC has much of central IL in a slight
chance of severe storms Monday afternoon/evening for damaging winds
and large hail. Surface to 6km bulk shear around 40 kts and CAPES
2-3K J/Kg supports this risk of severe storms from I-70 nw.
Upper level flow to become zonal by middle of next week and frontal
boundary likely not to get too far south of IL. Thus will continue
chances of showers and thunderstorms Tue with best chances (40-50%)
in southeast IL closer to frontal boundary while slight chances nw
of IL river. Just slight chances by Wed-Thu night and quite warm and
humid with highs in the mid to upper 80s and even approaching
lower 90s over southern areas Thu and Friday. This is due to
upper level ridge of 593 dm 500 mb high building over KY/TN. Next
frontal boundary to press se toward IL later Friday into Saturday
of next week increasing chances of showers and thunderstorms followed
by cooler weather next weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 658 AM CDT SAT AUG 30 2014
Scattered showers continue this morning mainly east of KDEC and
could produce isolated MVFR cig/vsby. As daytime heating
begins...expecting intensification of thunderstorm activity.
Location/timing of thunderstorms still uncertain at this time so
have limited mention to VCTS after 16Z-18Z. After 00Z...drying
conditions expected to begin spreading eastward across Illinois.
Western TAF sites KPIA-KSPI likely to see fog formation overnight
while eastern TAF sites KDEC-KCMI could see continued showers
overnight until around 12Z and have left VCSH in forecast.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
340 PM EDT SAT AUG 30 2014
.SYNOPSIS...
ISSUED AT 335 PM EDT SAT AUG 30 2014
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS
THE AREA THIS EVENING AS LOW PRESSURE TRACKS INTO THE NORTHERN GREAT
LAKES. SOME STORMS WILL PRODUCE BRIEF HEAVY RAIN AND STRONG GUSTY
WINDS. DRIER AIR WILL BRIEFLY WORK INTO THE AREA ON SUNDAY BEFORE
A COLD FRONT BRINGS RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS
ON MONDAY. LOWS WILL BE NEAR 70 WITH HIGHS ON SUNDAY AND MONDAY IN
THE LOW TO MID 80S.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 335 PM EDT SAT AUG 30 2014
CONVECTIVE DEVELOPMENT HAS TRIGGERED WHERE THE CLOUDS CLEARED
EARLIER TODAY...MAINLY OVER CENTRAL ILLINOIS TO LOWER LAKE
MICHIGAN AND INTO NORTHERN MICHIGAN. BEST SYNOPTIC SCALE FORCING
ASSOCIATED WITH THE LOW/TROF IN WISCONSIN. FLOW REGIME IS SUCH
THAT THE CONVECTION HAS DEVELOPED IN A STRETCHING DEFORMATION
AXIS. HRRR AND LOCAL WRF SHOW THE SFC BASED FRONTOGENESIS IN THIS
AXIS...
LAPSE RATES AND WIND PROFILES SUPPORT THE POTENTIAL FOR CONVECTIVE
LINES AND INDIVIDUAL LINE SEGMENTS. ISOLATED THREAT FOR SEVERE WIND
GUSTS. DO NOT EXPECT TO SEE SUSTAINED CONVECTIVE DEVELOPMENT AS THE
BOUNDARY LAYER FORCING DOES NOT PERSIST MUCH PAST 04Z.
LOW LEVEL JET KICKS IN OVERNIGHT AND THIS SHOULD BE ENOUGH TO
SUSTAIN MORE ORGANIZED SHRA/TSRA ACROSS THE SOUTHEASTERN HALF OF THE
FORECAST AREA. WHILE THERE IS DISCREPANCY IN TIMING AND INTENSITY
BETWEEN THE MODELS...THE BOUNDARY LAYER CAPE AND WIND PROFILES ARE
VERY SIMILAR AND DO SUPPORT PERSISTENT/LINGERING SHOWERS THROUGH
SUNDAY MORNING. WITH ABUNDANT MOISTURE TAP AND A LONG FETCH OF
ISENTROPIC ASSENT...SOME OF THE SHOWERS COULD PRODUCE MODERATE TO
LOCALLY HEAVY RAINFALL.
AS THE LOW LEVEL JET DECREASES AND THE TROF/DEFORMATION AXIS SHIFTS
EASTWARD...EXPECT IMPROVING CONDITIONS DURING THE DAY SUNDAY AHEAD
OF ANOTHER MORE ROBUST SYNOPTIC SYSTEM APPROACHING THE AREA FOR
MONDAY.
&&
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 335 PM EDT SAT AUG 30 2014
MAIN FOCUS OF LONG TERM IS ON PRECIP/SEVERE WEATHER CHANCES MONDAY
INTO MONDAY NIGHT. WELL DEFINED MID/UPPER LEVEL TROUGH CURRENTLY
DIGGING INTO THE PACIFIC NORTHWEST WILL SWING THROUGH THE GREAT
LAKES LATE MONDAY. TROUGH WILL BE LIFTING AS IT MOVES THROUGH THE
REGION BUT STRONG PUSH OF HEIGHT FALLS AND CVA WILL SUPPORT A DECENT
SURFACE CYCLONE AND ATTENDANT COLD FRONT. PRECIP CHANCES WILL BE
FURTHER AIDED BY GOOD RIGHT ENTRANCE JET DYNAMICS OVER THE SOUTHERN
GREAT LAKES. DEEP AND STRONG SOUTHWEST FLOW AHEAD OF THE TROUGH WILL
EASILY ADVECT HIGH THETA-E AIRMASS BACK INTO OUR AREA ON MONDAY.
AFTERNOON SBCAPE VALUES EXPECTED TO REACH THE 2-3 KJ/KG RANGE AS
HIGH TEMPS CLIMB INTO THE MID...OR PERHAPS UPPER...80S WITH SURFACE
DEWPOINTS IN THE LOW 70S. VERY DYNAMIC WAVE WILL LIKELY SUPPORT
NUMEROUS SHOWERS AND THUNDERSTORMS BUT TIMING WILL BE CRITICAL TO
SEVERE WEATHER CHANCES. LATEST 12Z NWP SUITE KEEPS SURFACE BOUNDARY
WEST OF OUR CWA UNTIL TUESDAY MORNING. ISO/SCT CONVECTION MAY
DEVELOP IN THE WARM SECTOR MONDAY AFTERNOON ALONG WEAK PREFRONTAL
TROUGH AS SUGGESTED BY THE LATEST NAM12 BUT EXPECT BULK OF THE
ACTIVITY WILL BE TIED TO THE ACTUAL COLD FRONT LATE MONDAY NIGHT.
BETTER WIND PROFILES...WITH 0-6KM SHEAR OF 30+ KNOTS...WILL ALSO BE
TIED CLOSER TO THE FRONT. DESPITE MORE THAN ADEQUATE
SHEAR...MIDLEVEL LAPSE RATES OF 6-7 C/KM ARE ONLY WEAKLY SUPPORTIVE
OF A NOCTURNAL SEVERE WEATHER THREAT. FORECAST SOUNDINGS INDICATE
ONLY AROUND 1000 J/KG OF ELEVATED INSTABILITY MONDAY NIGHT....PLENTY
FOR WIDESPREAD THUNDERSTORMS BUT SEVERE POTENTIAL IS LESS CLEAR.
THERE WILL BE A THREAT FOR SEVERE WINDS...AND POTENTIAL
ROTATION...WITH ANY SUBSTANTIVE UPDRAFTS THAT MANAGE TO DEVELOP BUT
LATE ARRIVAL OF FRONT MAY LIMIT CHANCES FOR A WIDESPREAD SEVERE
WEATHER EVENT. PUSHED BACK TIMING OF POPS BUT ALSO INCREASED THEM A
BIT BASED ON LATEST MODEL SOLUTIONS. COULD ALSO BE A THREAT FOR
STRONGER STORMS IN OUR FAR SOUTHEAST COUNTIES LATE TUESDAY MORNING
IF SURFACE BOUNDARY IS SLOW ENOUGH TO EXIT THE CWA.
QUIET WEATHER EXPECTED MIDWEEK BEFORE ANOTHER TROUGH APPROACHES NEXT
WEEKEND. SCT CONVECTION MAY BE POSSIBLE THURSDAY INTO FRIDAY AS WARM
FRONT LIFTS NORTH ONCE AGAIN BUT BEST CHANCES LOOK TO HOLD OFF UNTIL
THE WEEKEND. AFTER A BRIEF BREAK TUES AND WED...HEAT AND HUMIDITY
WILL RETURN FOR THE END OF THE WEEK AS ACTIVE WEATHER PATTERN
CONTINUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 335 PM EDT SAT AUG 30 2014
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 142 PM EDT SAT AUG 30 2014
ABUMNDANT MOISTURE WILL CONTINUE TO SPREAD MVFR CONDITIONS
THROUGHOUT THE FORECAST PERIOD. WEAK COLD FRONT/SFC TROF HAS
CROSSED THE IL/IN BORDER AND CONVECTIVE DEVELOPMENT IS TRIGGERING
ALONG THE CLEARING / DIFFERENTIAL HEATING BOUNDARY IN ILLINOIS.
GIVEN SURFACE BASED CAPES AND CLEARING THIS WILL LIKELY BE THE
MOST FAVORED AREA FOR CONTINUED DEVELOPMENT LATE THIS AFTERNOON
THROUGH EARLY EVENING.
LAMINAR FLOW WILL KEEP CONVECTION MOVING QUICKLY NORTHEASTWARD
THROUGH THE LATE EVENING. LOW LEVEL JET KICKS UP AFTER SUNSET AND
COULD BE THE FOCUS FOR CONVECTIVE RE-DEVELOPMENT...ESPECIALLY KSBN
AND NORTH.
LATE TONIGHT/EARLY SUNDAY MORNING EXPECT TO SEE FOG FORM...
ESPECIALLY ACROSS THE WESTERN HALF OF THE FORECAST AREA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LMZ043-046.
&&
$$
SYNOPSIS...STEINWEDEL
SHORT TERM...LEWIS
LONG TERM...AGD
AVIATION...LEWIS
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSNORTHERNINDIANA
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
838 PM CDT SUN AUG 31 2014
.UPDATE...
ISSUED AT 820 PM CDT SUN AUG 31 2014
EVENING UPDATE FOR TIMING/INTENSITY OF THUNDERSTORMS INTO THE
FORECAST AREA LATE TONIGHT INTO MONDAY MORNING.
LATEST RADAR TRENDS...MODELED WELL BY THE HRRR/RAP...INDICATE
STORMS PUSHING INTO THE WESTERN FRINGE OF THE FORECAST AREA NEAR
AND AFTER 11 PM CDT. HAVE UPDATED FORECAST GRIDS TO ADJUST TIMING
AND BRING HIGHER POPS IN EARLIER. DESPITE THE COOLING BOUNDARY
LAYER...THE COMPLEX MOVING INTO CENTRAL IOWA MAY BE ABLE TO
SUSTAIN A DAMAGING WIND THREAT UNTIL 2 OR 3 AM CDT. CONVECTION
STILL EXPECTED TO WEAKEN OVERNIGHT AND DECREASE IN COVERAGE NEAR
AND EAST OF THE MISSISSIPPI RIVER. HAVE UPDATED THE HAZARDOUS
WEATHER OUTLOOK TO REFLECT FORECAST CHANGES.
&&
.SYNOPSIS...
ISSUED AT 313 PM CDT SUN AUG 31 2014
A WARM...MID SUMMER-LIKE DAY IS FOUND OVER OUR CWA TODAY AS WE
REMAIN WELL EAST OF THE COLD FRONT APPROACHING IOWA THIS AFTERNOON.
THE COLD FRONT IS SLOWLY MOVING EAST...AND HAS ALREADY SPAWNED A FEW
HIGH BASED THUNDERSTORMS FROM SOUTHERN MN TO FAR EASTERN NE.
TEMPERATURES WITH FULL SUN TODAY HAVE REACHED THE MID 80S AS OF 2
PM...AND APPEAR SET FOR HIGHS IN THE MID TO UPPER 80S BEFORE CLOUDS
INTERRUPT THE HEATING LATER THIS AFTERNOON. SURFACE BASED STORMS
REMAIN CAPPED FOR NOW...THOUGH CAPE VALUES ARE SHOWN ON RAP DATA TO BE
2000 TO 4000 J/KG.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 313 PM CDT SUN AUG 31 2014
THERE IS LITTLE DOUBT THERE WILL BE AN IMPRESSIVE CONVECTIVE EVENT
TONIGHT. THERE IS PLENTY OF DOUBT THAT IT WILL STRONGLY AFFECT MORE
THAN JUST THE WESTERN MOST PORTION OF OUR CWA. THE SLOW MOVING
FRONT SHOULD BE ENOUGH TO FOCUS STORMS WITH PLENTY OF CAPE AND
MOISTURE AVAILABLE TO THE WEST...LIKELY NEAR THE MISSOURI RIVER.
THEY SHOULD MOVE EAST...SLOWLY. THIS PLACES THE WEAKENING PHASE OF
THE COMPLEX INTO EASTERN IOWA BETWEEN MIDNIGHT AND 9 AM MONDAY. THIS
POOR DIURNAL TIMING COMBINED WITH LESS THAN IDEAL MOISTURE TRANSPORT
DURING THAT TIME FRAME SUGGESTS BOTH INTENSITY AND COVERAGE OF
STORMS WILL BE ON THE WANE IN THAT PERIOD. I HAVE CONFINED HIGH POPS
TO ONLY THE WESTERN CWA LATE TONIGHT...AND LOWERED TO CHANCE FOR
MONDAY MORNING SINCE MOST MODELS SUGGEST A FRAGMENTED LINE...AND
THAT SEEMS MOST LIKELY TO ME AS WELL. QPF SHOULD BE IMPRESSIVE TO
THE WEST...BUT MAY BE INSIGNIFICANT IN OUR CWA...GENERALLY 0.25 OR
LESS IN ALL BE THE FAR WEST...WHERE 0.5 TO 1.0 IS POSSIBLE.
MONDAY WILL SEE FAR BETTER DYNAMICS...THUS THE SPC OUTLOOK FOR
SEVERE WEATHER. HOWEVER...THE CONVERGENT OUTFLOW BOUNDARY WILL
LIKELY BE WELL IN ADVANCE OF THE COLD FRONT...WHICH SHOULD ALSO
DEFLECT THE STRONGEST HEATING WELL EAST OF THE CWA AS WELL.
THUS...THE WEAKENING CONVECTIVE DEBRIS SHOULD INHIBIT OUR MONDAY
SEVERE POTENTIAL...AS WELL AS WIDESPREAD RAIN POTENTIAL AGAIN. SURE
SEEMS THIS EVENT SHOULD PRODUCE THE MAJORITY OF ITS RAIN WEST AND
SOUTHEAST OF OUR CWA.
ERVIN
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 313 PM CDT SUN AUG 31 2014
THE FRONT WILL CLEAR THE SOUTHEAST HALF OF THE AREA LATE MONDAY
EVENING. THE SOUTHEAST HALF OF THE AREA SHOULD SEE PRECIPITATION
ONGOING AT SUNSET THAT ENDS FROM NORTHWEST TO SOUTHEAST AFTER
MIDNIGHT. DRIER AIR MOVING INTO THE AREA SHOULD RESULT IN LOWS NEAR
OR SLIGHTLY BELOW NORMAL BY SUNRISE TUESDAY.
TUESDAY/TUESDAY NIGHT DRY CONDITIONS ARE EXPECTED AS HIGH PRESSURE
MOVES THROUGH THE MIDWEST. TEMPERATURES SHOULD BE CLOSE TO NORMAL.
WEDNESDAY MORNING LOOKS TO BE DRY ACROSS THE AREA AS THE HIGH MOVES
TOWARD THE EAST COAST. A WEAK DISTURBANCE WILL MOVE THROUGH THE AREA
WEDNESDAY AFTERNOON. THE OVERALL FORCING IS NOT STRONG AND MOISTURE
AVAILABILITY IS IN QUESTION. IF PRECIPITATION DOES OCCUR IT WOULD BE
ISOLATED IN NATURE WITH THE SOUTH HALF BEING FAVORED.
WEDNESDAY NIGHT ON...
THE MODEL CONSENSUS HAS SLIGHT CHANCE TO CHANCE POPS IN EACH 12 HR
PERIOD FROM WEDNESDAY NIGHT THROUGH SATURDAY.
THERE IS A WEAK DISTURBANCE MOVING THROUGH THE AREA WEDNESDAY
NIGHT/THURSDAY. MOISTURE AVAILABILITY WILL BE ON THE INCREASE BUT
THE OVERALL FORCING IS NOT STRONG. THE POSSIBILITY DOES EXIST THERE
WILL BE PERIODS OF DRY WEATHER WEDNESDAY NIGHT/THURSDAY.
THE MODELS DIFFER SOMEWHAT ON THE TIMING BUT AGREE THAT ANOTHER COLD
FRONT WILL MOVE THROUGH THE AREA IN THE THURSDAY NIGHT THROUGH
FRIDAY NIGHT TIME FRAME.
SEVERAL MODELS ARE PUSHING A SIGNIFICANT HIGH INTO THE WESTERN GREAT
LAKES ON SATURDAY. THE CURRENT MODEL CONSENSUS HAS SLIGHT CHANCE
POPS ACROSS THE SOUTH QUARTER OF THE AREA BUT THE OVERALL TREND IS
SUGGESTING DECREASING PRECIPITATION CHANCES.
SATURDAY NIGHT THROUGH SUNDAY THE MODEL CONSENSUS HAS DRY CONDITIONS
WITH HIGH PRESSURE OVER THE GREAT LAKES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 633 PM CDT SUN AUG 31 2014
FOR THE 00Z TAF ISSUANCE...MADE SOME MINOR CHANGES TO TIMING OF
THUNDERSTORMS EXPECTED TO MOVE FROM WEST TO EAST ACROSS THE AREA
OVERNIGHT. VCTS GROUPS NOW BEGIN AT 06Z AT KCID AND 07Z AT
KDBQ/KBRL...WITH TEMPO GROUPS TO COVER HIGHER INTENSITY STORMS
WITH MVFR/IFR CIGS AND/OR VSBYS. QUESTIONS LINGER ABOUT THE
COVERAGE/INTENSITY OF THE STORMS INVOF KMLI AND POINTS EAST LATE
TONIGHT. ANY AFTERNOON REDEVELOPMENT ALONG THE COLD FRONT WOULD BE
FAVORED AT KMLI/KBRL...BUT NOT ENOUGH CONFIDENCE TO INTRODUCE IN
LATER PERIOD OF TAF AT THIS TIME.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...RP KINNEY
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...08
AVIATION...RP KINNEY
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
653 PM CDT SUN AUG 31 2014
.SYNOPSIS...
ISSUED AT 313 PM CDT SUN AUG 31 2014
A WARM...MID SUMMER-LIKE DAY IS FOUND OVER OUR CWA TODAY AS WE
REMAIN WELL EAST OF THE COLD FRONT APPROACHING IOWA THIS AFTERNOON.
THE COLD FRONT IS SLOWLY MOVING EAST...AND HAS ALREADY SPAWNED A FEW
HIGH BASED THUNDERSTORMS FROM SOUTHERN MN TO FAR EASTERN NE.
TEMPERATURES WITH FULL SUN TODAY HAVE REACHED THE MID 80S AS OF 2
PM...AND APPEAR SET FOR HIGHS IN THE MID TO UPPER 80S BEFORE CLOUDS
INTERRUPT THE HEATING LATER THIS AFTERNOON. SURFACE BASED STORMS
REMAIN CAPPED FOR NOW...THOUGH CAPE VALUES ARE SHOWN ON RAP DATA TO BE
2000 TO 4000 J/KG.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 313 PM CDT SUN AUG 31 2014
THERE IS LITTLE DOUBT THERE WILL BE AN IMPRESSIVE CONVECTIVE EVENT
TONIGHT. THERE IS PLENTY OF DOUBT THAT IT WILL STRONGLY AFFECT MORE
THAN JUST THE WESTERN MOST PORTION OF OUR CWA. THE SLOW MOVING
FRONT SHOULD BE ENOUGH TO FOCUS STORMS WITH PLENTY OF CAPE AND
MOISTURE AVAILABLE TO THE WEST...LIKELY NEAR THE MISSOURI RIVER.
THEY SHOULD MOVE EAST...SLOWLY. THIS PLACES THE WEAKENING PHASE OF
THE COMPLEX INTO EASTERN IOWA BETWEEN MIDNIGHT AND 9 AM MONDAY. THIS
POOR DIURNAL TIMING COMBINED WITH LESS THAN IDEAL MOISTURE TRANSPORT
DURING THAT TIME FRAME SUGGESTS BOTH INTENSITY AND COVERAGE OF
STORMS WILL BE ON THE WANE IN THAT PERIOD. I HAVE CONFINED HIGH POPS
TO ONLY THE WESTERN CWA LATE TONIGHT...AND LOWERED TO CHANCE FOR
MONDAY MORNING SINCE MOST MODELS SUGGEST A FRAGMENTED LINE...AND
THAT SEEMS MOST LIKELY TO ME AS WELL. QPF SHOULD BE IMPRESSIVE TO
THE WEST...BUT MAY BE INSIGNIFICANT IN OUR CWA...GENERALLY 0.25 OR
LESS IN ALL BE THE FAR WEST...WHERE 0.5 TO 1.0 IS POSSIBLE.
MONDAY WILL SEE FAR BETTER DYNAMICS...THUS THE SPC OUTLOOK FOR
SEVERE WEATHER. HOWEVER...THE CONVERGENT OUTFLOW BOUNDARY WILL
LIKELY BE WELL IN ADVANCE OF THE COLD FRONT...WHICH SHOULD ALSO
DEFLECT THE STRONGEST HEATING WELL EAST OF THE CWA AS WELL.
THUS...THE WEAKENING CONVECTIVE DEBRIS SHOULD INHIBIT OUR MONDAY
SEVERE POTENTIAL...AS WELL AS WIDESPREAD RAIN POTENTIAL AGAIN. SURE
SEEMS THIS EVENT SHOULD PRODUCE THE MAJORITY OF ITS RAIN WEST AND
SOUTHEAST OF OUR CWA.
ERVIN
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 313 PM CDT SUN AUG 31 2014
THE FRONT WILL CLEAR THE SOUTHEAST HALF OF THE AREA LATE MONDAY
EVENING. THE SOUTHEAST HALF OF THE AREA SHOULD SEE PRECIPITATION
ONGOING AT SUNSET THAT ENDS FROM NORTHWEST TO SOUTHEAST AFTER
MIDNIGHT. DRIER AIR MOVING INTO THE AREA SHOULD RESULT IN LOWS NEAR
OR SLIGHTLY BELOW NORMAL BY SUNRISE TUESDAY.
TUESDAY/TUESDAY NIGHT DRY CONDITIONS ARE EXPECTED AS HIGH PRESSURE
MOVES THROUGH THE MIDWEST. TEMPERATURES SHOULD BE CLOSE TO NORMAL.
WEDNESDAY MORNING LOOKS TO BE DRY ACROSS THE AREA AS THE HIGH MOVES
TOWARD THE EAST COAST. A WEAK DISTURBANCE WILL MOVE THROUGH THE AREA
WEDNESDAY AFTERNOON. THE OVERALL FORCING IS NOT STRONG AND MOISTURE
AVAILABILITY IS IN QUESTION. IF PRECIPITATION DOES OCCUR IT WOULD BE
ISOLATED IN NATURE WITH THE SOUTH HALF BEING FAVORED.
WEDNESDAY NIGHT ON...
THE MODEL CONSENSUS HAS SLIGHT CHANCE TO CHANCE POPS IN EACH 12 HR
PERIOD FROM WEDNESDAY NIGHT THROUGH SATURDAY.
THERE IS A WEAK DISTURBANCE MOVING THROUGH THE AREA WEDNESDAY
NIGHT/THURSDAY. MOISTURE AVAILABILITY WILL BE ON THE INCREASE BUT
THE OVERALL FORCING IS NOT STRONG. THE POSSIBILITY DOES EXIST THERE
WILL BE PERIODS OF DRY WEATHER WEDNESDAY NIGHT/THURSDAY.
THE MODELS DIFFER SOMEWHAT ON THE TIMING BUT AGREE THAT ANOTHER COLD
FRONT WILL MOVE THROUGH THE AREA IN THE THURSDAY NIGHT THROUGH
FRIDAY NIGHT TIME FRAME.
SEVERAL MODELS ARE PUSHING A SIGNIFICANT HIGH INTO THE WESTERN GREAT
LAKES ON SATURDAY. THE CURRENT MODEL CONSENSUS HAS SLIGHT CHANCE
POPS ACROSS THE SOUTH QUARTER OF THE AREA BUT THE OVERALL TREND IS
SUGGESTING DECREASING PRECIPITATION CHANCES.
SATURDAY NIGHT THROUGH SUNDAY THE MODEL CONSENSUS HAS DRY CONDITIONS
WITH HIGH PRESSURE OVER THE GREAT LAKES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 633 PM CDT SUN AUG 31 2014
FOR THE 00Z TAF ISSUANCE...MADE SOME MINOR CHANGES TO TIMING OF
THUNDERSTORMS EXPECTED TO MOVE FROM WEST TO EAST ACROSS THE AREA
OVERNIGHT. VCTS GROUPS NOW BEGIN AT 06Z AT KCID AND 07Z AT
KDBQ/KBRL...WITH TEMPO GROUPS TO COVER HIGHER INTENSITY STORMS
WITH MVFR/IFR CIGS AND/OR VSBYS. QUESTIONS LINGER ABOUT THE
COVERAGE/INTENSITY OF THE STORMS INVOF KMLI AND POINTS EAST LATE
TONIGHT. ANY AFTERNOON REDEVELOPMENT ALONG THE COLD FRONT WOULD BE
FAVORED AT KMLI/KBRL...BUT NOT ENOUGH CONFIDENCE TO INTRODUCE IN
LATER PERIOD OF TAF AT THIS TIME.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...08
AVIATION...RP KINNEY
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1146 PM CDT FRI AUG 29 2014
.SYNOPSIS...
ISSUED AT 1244 PM CDT FRI AUG 29 2014
A DEEP RICH MOISTURE PLUME CONTINUES TO FEED INTO EASTERN IOWA AND
MUCH OF THE UPPER MIDWEST. OUR CWA FELL WEST OF A FEW HEAVY RAIN
PRODUCING STORMS IN ILLINOIS EARLIER TODAY...AND UNDER A WEAK AREA
OF SUBSIDENCE THROUGH EARLY AFTERNOON. THIS HAS ALLOWED LOW LEVELS
TO HEAT UP UNINHIBITED. AS OF 1 PM...WIDESPREAD LOWER TO MID 80S ARE
FOUND OVER EASTERN IOWA AND WESTERN ILLINOIS...WITH DEWPOINTS IN THE
70 TO 73 RANGE. HIGHS TODAY SHOULD REACH THE MID TO UPPER 80S. CAPE
VALUES ESTIMATED BY SPC RAP AS OF 1 PM ARE 2000 TO 3000 OVER ALL OF
THE CWA. A VORTICITY MAXIMA IS LOCATED IN EASTERN KS...WITH A PVA
WING OF LIFT FOUND INTO CENTRAL MISSOURI. THIS IS ALREADY DEVELOPING
A LINE OF DEEP CONVECTION FROM NORTH CENTRAL TO SOUTH
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014
THE VORT MAX TO THE SOUTHWEST WILL LIFT THROUGH IOWA THIS
EVENING...HELPING ORGANIZE STORMS AS THEY MOVE THROUGH THE CWA. FROM
LATE AFTERNOON THROUGH MID EVENING...THESE SHOULD IMPACT MUCH OF THE
CWA. A LACK OF SHEAR SHOULD DECREASE ANY WIDESPREAD SEVERE WEATHER
THREAT...BUT SOME ISOLATED WIND DAMAGE IS POSSIBLE THROUGH WET
MICROBURST ACTIVITY IN THE STRONGEST CELLS. OTHERWISE....THIS SHOULD
BE HEAVY RAIN PRODUCING LINE OF STORMS...WITH SOME BRIEF TRAINING
POSSIBLE. A WIDESPREAD RAIN OF 0.25 TO 0.75 IS EXPECTED...WITH
SWATHS OF 1 TO 2 INCHES. WE ARE LIKELY TO HANDLE THIS MINOR
FLOOD/URBAN RUNOFF THREAT WITH SPS PRODUCTS.
TONIGHT...STORMS SHOULD BECOME LESS NUMEROUS...AND POSSIBLY END
FULLY. HOWEVER...WITH THE PARENT VORT MOVING BY WITH AMPLE
MOISTURE...WE WILL LEAVE POPS GOING THROUGH THE NIGHT.
SATURDAY...MODELS BRING ANOTHER QUICK SHOT OF ENERGY THROUGH WHILE
MOISTURE IS DEPARTING. THIS MAY BRING SOME SHOWERS AND STORMS TO
ROUGHLY THE EAST HALF...BUT SHOULD SUBSIDENCE BECOME MORE CONFIDENT
BEHIND TONIGHTS STORMS...WE MAY BE DRY ALL DAY SATURDAY.
TEMPERATURES LOOK MILD TONIGHT...IN THE UPPER 60S...WHILE SATURDAY
SHOULD SEE A DRY AFTERNOON REBOUND TO THE UPPER 70S TO LOWER 80S.
CLOUDS WHILE THICK IN THE MORNING SHOULD BECOME SCATTERED BY MID
DAY.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014
THE MAIN FORECAST CONCERN IN THE LONG TERM PERIOD IS STORM
COVERAGE/RAINFALL AMOUNTS/SEVERE POTENTIAL WITH THE ARRIVAL OF THE
NEXT SYSTEM SUNDAY NIGHT INTO MONDAY.
EARLY IN THE PERIOD...HAVE MAINTAINED DRY FORECAST FOR SATURDAY
NIGHT THROUGH SUNDAY AFTERNOON. MEDIUM RANGE MODELS HAVE CONTINUED
A GENERAL TREND OF SLOWING THE ARRIVAL OF THE NEXT FRONTAL
BOUNDARY AND UPPER LEVEL TROUGH. HAVE REDUCED AND TRIMMED POPS
BACK TO THE NORTHWEST FOR SUNDAY EVENING...AND ADDITIONAL
ADJUSTMENTS MAY BE NEEDED OVER THE NEXT COUPLE OF DAYS. THE MAIN
WINDOW OF SHOWERS/STORMS IS NOW EXPECTED LATE SUNDAY NIGHT INTO
MONDAY MORNING. THE LATER TIMING MEANS FAVORABLE SEVERE WEATHER
PARAMETERS WILL LIKELY STAY WEST OF THE FORECAST AREA...WITH THE
MOST LIKELY SCENARIO BEING A DECAYING MCS AND POSSIBLY SOME
LOCALLY HEAVY RAIN. STORMS MAY CONTINUE INTO THE AFTERNOON...AND
POSSIBLY MONDAY NIGHT DEPENDING ON HOW FAR SOUTH THE FRONT PUSHES.
LOOKING AHEAD...CONFIDENCE IN FORECAST DETAILS IS LOWER AS THE
OPERATIONAL GFS AND EURO VACILLATE BETWEEN WEAK TROUGHING AND
ZONAL FLOW ACROSS THE REGION. TIMING AND LOCATION OF THE VARIOUS
WEAK IMPULSES IS CHALLENGING AND RIGHT NOW THERE IS NO REASON TO
VARY FROM THE CONSENSUS BLEND POPS...ESSENTIALLY SLIGHT TO LOW
CHANCE IN EVERY PERIOD THROUGH FRIDAY. TEMPERATURES ARE EXPECTED
TO BE NEAR TO SLIGHT ABOVE NORMAL THROUGH THE PERIOD...WITH
AFTERNOON HIGHS GENERALLY IN THE 8OS AND LOWS IN THE 60S TO LOWER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1141 PM CDT FRI AUG 29 2014
UPPER LOW TO PASS ACROSS THE REGION THE NEXT 8-12 HOURS WITH LOTS OF
CLOUDS AND AREAS OF SHOWERS AND STORMS. MOSTLY VFR CONDITIONS ALL
TERMINALS WITH BRIEF MVFR CONDITIONS NEXT 4-6 HOURS POSSIBLE IN
ANY STORMS THAT ARE HANDLED AS A TEMPO GROUP AND VICINITY WORDING
UNTIL LATE OVERNIGHT HOURS. SKIES TO BECOME FAIR BY MID TO LATE
MORNING WITH CUMULUS CLOUD BASES ABOVE 3K AGL WITH VFR CONDITIONS
THROUGH AT LEAST 31/06Z AND CLEAR SKIES BY SUNSET. LIGHT SOUTH WINDS TO
BECOME WESTERLY AT 5 TO 10 KTS SATURDAY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...ERVIN
AVIATION...NICHOLS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1059 PM CDT Sun Aug 31 2014
.UPDATE...
Issued at 1055 PM CDT SUN AUG 31 2014
For aviation section only.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 238 PM CDT SUN AUG 31 2014
Wvapor and RAP data shows subtle mid level wave moving slowly
east across the area. Convection near SEMO making little eastward
progress. Tiny showers over west KY moving east as well. Will keep
PoPs limited through the early evening before ending them from
west to east overnight. Frontal boundary will approach the area
Monday night. Best chance of activity will be over far north and
west sections of the area. Cannot rule out isolated anywhere, but
chances too low down into west KY to include for now. Moisture is
increasingly limited south of the Ohio. PoPs will rise from NW to
SE Monday night as the front settles south toward the area. Again
best chances north, lowering south. Tuesday the front will stall
somewhere across the area, with upper level support moving across
the region. Thus the chance of convection continues. We could see
some strong storms Tuesday given degree of forecast instability,
and an uptick in the mean flow 850-500mb. Tuesday night we will
drop off PoPs in the wake of the upper system. However more
activity could move into or toward SEMO toward daybreak Wednesday.
Temps will be a blend of existing numbers and the latest blend of
raw model output.
.LONG TERM...(Wednesday through Sunday)
Issued at 238 PM CDT SUN AUG 31 2014
By Wednesday morning, whatever is left of the frontal boundary that
went through the area the night before, will be situated somewhere
over our southern counties. The front will be lifting back north as
a warm front and this is seen most evidently in the theta e fields.
This rebounding front along with minor perturbations in the zonal
flow aloft will likely lead to some convection, especially given the
decent mid level lapse rates, sfc instability parameters and deep
moisture. The upper wave will move off to the east Wednesday night
and things should be fairly quiet except for some possible lingering
afternoon convection.
On Thursday, the upper ridge really begins building over the region
and become centered over us by the end of the day. This should help
boost temperatures up a degree or two into the lower 90s. We should
not see widespread chances for storms though on Thursday, but it
appears as though a small chance will remain, with the best chances
in the east where the better moisture will be confined. Meanwhile, a
frontal boundary will be progressing eastward across the upper
Midwest down into the Central Plains. This front will be slow to
move and models have not been handling its speed very well. Toddy`s
runs of the GFS and ECMWF show a faster progression and have the
front into the area by Friday or Friday night. The best moisture and
QPF is behind the actual front so precipitation chances ramp up by
Friday night into Saturday.
Beyond Saturday, models were having a rough time resolving how
quickly the moisture gets shoved out of the area and this is due to
the differences in the strength and progression of the sfc high
originating from the north central plains states. But the 12Z model
runs of the GFS and ECMWF have finally aligned well and believe that
Sunday (and even Saturday night) should be dry now. In fact, much
drier and cooler air settling in with highs probably in the 70s on
Sunday.
&&
.AVIATION...
Issued at 1055 PM CDT SUN AUG 31 2014
VFR conditions can be expected throughout the TAF period. SW winds
on Monday will pick up into the 10-15 kt range as a pressure
gradient tightens ahead of a cold front in the Plains. Some gusts
could reach 20 kts during the day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...GM
AVIATION...GM
AREA FORECAST DISCUSSION
NWS PADUCAH KY
714 PM CDT Sun Aug 31 2014
.UPDATE...
Issued at 709 PM CDT SUN AUG 31 2014
For aviation section only.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 238 PM CDT SUN AUG 31 2014
Wvapor and RAP data shows subtle mid level wave moving slowly
east across the area. Convection near SEMO making little eastward
progress. Tiny showers over west KY moving east as well. Will keep
PoPs limited through the early evening before ending them from
west to east overnight. Frontal boundary will approach the area
Monday night. Best chance of activity will be over far north and
west sections of the area. Cannot rule out isolated anywhere, but
chances too low down into west KY to include for now. Moisture is
increasingly limited south of the Ohio. PoPs will rise from NW to
SE Monday night as the front settles south toward the area. Again
best chances north, lowering south. Tuesday the front will stall
somewhere across the area, with upper level support moving across
the region. Thus the chance of convection continues. We could see
some strong storms Tuesday given degree of forecast instability,
and an uptick in the mean flow 850-500mb. Tuesday night we will
drop off PoPs in the wake of the upper system. However more
activity could move into or toward SEMO toward daybreak Wednesday.
Temps will be a blend of existing numbers and the latest blend of
raw model output.
.LONG TERM...(Wednesday through Sunday)
Issued at 238 PM CDT SUN AUG 31 2014
By Wednesday morning, whatever is left of the frontal boundary that
went through the area the night before, will be situated somewhere
over our southern counties. The front will be lifting back north as
a warm front and this is seen most evidently in the theta e fields.
This rebounding front along with minor perturbations in the zonal
flow aloft will likely lead to some convection, especially given the
decent mid level lapse rates, sfc instability parameters and deep
moisture. The upper wave will move off to the east Wednesday night
and things should be fairly quiet except for some possible lingering
afternoon convection.
On Thursday, the upper ridge really begins building over the region
and become centered over us by the end of the day. This should help
boost temperatures up a degree or two into the lower 90s. We should
not see widespread chances for storms though on Thursday, but it
appears as though a small chance will remain, with the best chances
in the east where the better moisture will be confined. Meanwhile, a
frontal boundary will be progressing eastward across the upper
Midwest down into the Central Plains. This front will be slow to
move and models have not been handling its speed very well. Todays
runs of the GFS and ECMWF show a faster progression and have the
front into the area by Friday or Friday night. The best moisture and
QPF is behind the actual front so precipitation chances ramp up by
Friday night into Saturday.
Beyond Saturday, models were having a rough time resolving how
quickly the moisture gets shoved out of the area and this is due to
the differences in the strength and progression of the sfc high
originating from the north central plains states. But the 12Z model
runs of the GFS and ECMWF have finally aligned well and believe that
Sunday (and even Saturday night) should be dry now. In fact, much
drier and cooler air settling in with highs probably in the 70s on
Sunday.
&&
.AVIATION...
Issued at 710 PM CDT SUN AUG 31 2014
VFR conditions can be expected throughout the TAF period. SW winds
on Monday will pick up into the 10-15 kt range as a pressure
gradient tightens ahead of a cold front in the Plains. Some gusts
could reach 20 kts during the day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...GM
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1127 PM CDT FRI AUG 29 2014
.AVIATION UPDATE...REGARDING 06Z TAF ISSUANCE. RADAR DEPICTING A
A BAND OF LIGHT STRATOFORM RAINS FROM THE COASTAL WATERS...THROUGH
ACADIANA AND INTO CENTRAL LOUISIANA. A FEW SHOWERS AND
THUNDERSTORMS ARE NOTED OVER THE NORTHWEST GULF SOUTH OF SABINE
PASS WHERE A LOW/MID LEVEL CIRCULATION IS IN PLACE...WITH FEATURE
PROGGED TO ADVANCE SLOWLY NORTHWARD ABOUT THE PERIPHERY OF
SUBTROPICAL RIDGE.
EXPECTED INCREASING AREA COVERAGE OF CONVECTION INLAND OVER THE
NEXT FEW HOURS AS LOW LEVEL CONVERGENCE RAPIDLY BECOMES
ESTABLISHED IN CONCERT WITH A DEVELOPING LOW LEVEL JET ASSOCIATED
WITH AFOREMENTIONED FEATURE. HAVE OPTED FOR INITIAL TEMPO GROUPS
FOR CONVECTION TRANSITIONING INTO PREVAILING LATER TONIGHT.
&&
MARCOTTE
&&
.PREV DISCUSSION... /ISSUED 926 PM CDT FRI AUG 29 2014/
DISCUSSION...
MAIN SHRA/ISO TSRA AREA OVER THE GULF THIS EVENING...WITH
LIGHT/MOD SHRA SPREADING INLAND ACROSS SE TX/S LA. NOTABLE MID
LEVEL SPIN JUST OFF THE SE TX COAST...ASSOCIATED WITH THE REMNANT
MID LEVEL VORT MAX FROM THE EARLIER TSRA CLUSTER OVER THE NW GULF.
THE NAM & HRRR CONTINUES TO SIGNAL ADDITIONAL DEVELOPMENT OF
SHRA/TSRA OVER EXTREME SE TX/S LA BETWEEN 06-12Z...WITH POSSIBLE
TRAINING OF ECHOS SETTING UP TOWARDS DAYBREAK INTO THE REMAINDER
OF THE MORNING ONCE THIS REMNANT VORT MAX MOVES INLAND AND
INCREASED LIFT SETS UP FROM THE APPROACHING UPPER LEVEL TROF. WITH
THE HIGH PRECIP H20 VALUES ALREADY IN PLACE (00Z LCH SOUNDING @
2.27") WILL NOT TAKE MUCH TO GET 2-3" OF RAINFALL...WITH LOCALLY
HIGHER AMOUNTS OF 3-5" POSSIBLE BEFORE ALL SAID AND DONE BY SAT
EVENING/EARLY SUN. THIS WARRANTED THE ISSUANCE OF A FLASH FLOOD
WATCH FOR SE TX/C AND S LA. BELIEVE THE MAIN THREAT AREA FOR THE
OVERNIGHT HOURS WILL BE ALONG AND SOUTH OF I-10...WITH THIS AREA
SHIFTING NORTHWARD AFTER DAYBREAK FOR THE REMAINDER OF THE WATCH AREA.
DML
PREV DISCUSSION... /ISSUED 633 PM CDT FRI AUG 29 2014/
UPDATE...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS NOW PRIMARILY
OVER THE NEAR COASTAL WATERS ARE EXPECTED TO MOVE INLAND AS THE
NIGHT PROGRESSES. THIS ACTIVITY IS ASSOCIATED WITH LOW
PRESSURE OVER THE NORTHWEST GULF ADVANCING NORTHWARD. INITIAL VFR
CEILINGS ARE EXPECTED TO SLIP DOWN WITHIN MVFR.
MARCOTTE
PREV DISCUSSION... /ISSUED 411 PM CDT FRI AUG 29 2014/
DISCUSSION...
SHOWERS HAVE DROPPED RAINS ACROSS A LARGE PORTION OF SE TX AND
SRN LA TODAY...GENERALLY LESS THAN 1/2 INCH MOST LOCATIONS. THIS
HAS HELP TO KEEP TEMPERATURES IN THE 80S. RAINS ARE FROM A LOW
OFF OF BRO THAT HAS BEEN DRAGGING MOISTURE NORTHWARD. THIS
PATTERN WILL CONTINUE INTO THE OVERNIGHT HOURS WITH ADDITIONAL
SHOWERS AND THUNDERSTORMS ON TAP. TEMPS WILL FALL INTO THE MID 70S
MOST LOCATIONS BUT A FEW LOCATIONS MAY SEE LOWER 70S WITH RAIN
COOLED AIR.
TOMORROW WILL SEE ANOTHER SURGE OF MOISTURE INTO THE REGION FROM
THE GULF AND RAIN CHANCES WILL INCREASE AND TEMPS ARE EXPECTED
BACK INTO THE 80S ONCE AGAIN. RAINFALL TOTALS EXPECTED AROUND ONE
TO TWO INCHES WITH ISOLATED LOCATIONS GETTING THREE TO FOUR
INCHES. THE MOISTURE AXIS WILL CONTINUE INTO SUNDAY BUT RAIN
CHANCES WILL TAPER OFF A BIT... BUT BY MONDAY HIGH PRESSURE WILL
BUILD IN FROM THE EAST AND THIS WILL BEGIN TO SHUT OFF OUR PRECIP.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 74 85 75 89 76 / 90 90 50 40 10
KBPT 74 87 76 90 76 / 80 80 50 40 10
KAEX 73 84 72 89 73 / 70 90 50 40 10
KLFT 75 84 75 90 76 / 90 90 50 40 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING
ZONES: ACADIA...ALLEN...AVOYELLES...BEAUREGARD...
CALCASIEU...EAST CAMERON...EVANGELINE...IBERIA...JEFFERSON
DAVIS...LAFAYETTE...LOWER ST. MARTIN...RAPIDES...ST.
LANDRY...ST. MARY...UPPER ST. MARTIN...VERMILION...VERNON...
WEST CAMERON.
TX...FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING
ZONES: JEFFERSON...ORANGE.
GM...SMALL CRAFT EXERCISE CAUTION UNTIL 7 AM CDT SATURDAY FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH
ISLAND TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY
TO CAMERON LA OUT 20 NM...COASTAL WATERS FROM LOWER
ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA OUT 20 NM...
WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM 20 TO 60
NM...WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM 20 TO 60
NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL
CITY LA FROM 20 TO 60 NM.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
1012 PM EDT SUN AUG 31 2014
.SYNOPSIS...
A COLD FRONT WILL DROP SOUTHEAST THROUGH THE REGION O0VERNIGHT
AND WILL STALL OFF THE COAST ON MONDAY. A SECOND COLD FRONT WILL
APPROACH FROM THE WEST ON TUESDAY AND WILL CROSS THE REGION
TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST ON
WEDNESDAY AND WILL CREST OVER THE REGION THURSDAY BEFORE SHIFTING
OFFSHORE. HIGH PRESSURE WILL HOLD OFF THE NEW ENGLAND COAST ON
FRIDAY. A COLD FRONT WILL CROSS THE AREA ON SATURDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
UPDATE...SHOWERS AND EMBEDDED TSTMS CONTINUE TO SLOWLY MOVE EWD
ACROSS THE SRN PART OF THE FORECAST AREA. IN A LINE FROM JUST E OF
KCON TO KPWM RAIN IS HEAVY AT TIMES...WITH OCNL RATES IN EXCESS OF
3 INCHES/HR. BACK EDGE IS QUICKLY APPROACHING THE COAST...THOUGH
HEAVIEST RATES WILL LINGER WITHIN THIS LINE. TO EITHER SIDE OF
THAT LINE...A LIGHTER RAIN WILL CONTINUE TO FALL FOR THE NEXT
COUPLE OF HOURS. HAVE ADJUSTED POP BASED ON RADAR TREND AND LATEST
HI-RES MODEL GUIDANCE. SHOULD BE A MOSTLY DRY NIGHT ONCE THIS RNFL
CLEARS THE COAST...EXCEPT FOR THE FAR NRN ZONES WHERE LINGERING
CONVECTION ASSOCIATED WITH LEADING EDGE OF S/WV TROF MAY HOLD
TOGETHER.
PREVIOUS DISCUSSION...A SHORT WAVE TROUGH APPROACHING FROM THE
WEST WILL WEAKEN THIS EVENING AS IT MOVES EASTWARD TOWARD NORTHERN
NEW ENGLAND. THE ATTENDANT SFC COLD FRONT WILL APPROACH AS
WELL...AND ALSO WEAKEN. A SHIELD OF LIGHT RAIN CONTINUES TO
TRAVERSE ACROSS NORTHERN AND CENTRAL ZONES AS OF 19Z THIS SUNDAY
AFTERNOON. THIS WILL STABILIZE THE AIRMASS ACROSS THIS AREA.
HOWEVER...ALONG THE COASTAL PLAIN SWWD OVER TO SOUTHERNMOST NH
SHOULD REMAIN MOSTLY DRY FOR THE NEXT SEVERAL HOURS.
THEREFORE...THESE AREAS SHOULD RETAIN THE INSTABILITY /1000-1500
J/KG SBCAPE/ THROUGH EARLY EVENING. THE QUESTION IS DO
THUNDERSTORMS DEVELOP IN THIS AREA.
SEVERAL OF THE LATEST RUNS OF THE HRRR CONTINUE TO SHOW
THUNDERSTORMS WILL HEAVY RAINFALL MOVING ACROSS SOUTHERNMOST NH
AND SOUTHERNMOST ME BETWEEN 22Z AND 03Z. THIS SEEMS REASONABLE
GIVEN THE CURRENT MESOSCALE SETUP. AS A RESULT WILL CONTINUE WITH
HIGH POPS...ESPECIALLY IN THIS AREA. MODERATE DEEP LAYER SHEAR MAY
AID IN A FEW OF THESE STORMS BECOMING STRONG...WITH GUSTY WINDS
BEING THE MAIN THREAT. WITH PWATS INCREASING TO AROUND 2 INCHES BY
EARLY EVENING...TORRENTIAL DOWNPOURS WILL BE LIKELY IN ANY
THUNDERSTORM. THERE IS A LOW PROB FOR TRAINING STORMS ACROSS
SOUTHERN NH AND SOUTHERNMOST ME...SO LOCALIZED FLASH FLOODING WILL
BE POSSIBLE THIS EVENING. THE BULK OF THE ACTIVITY SHOULD MOVE
OFFSHORE AROUND MIDNIGHT LEADING TO A MAINLY DRY OVERNIGHT.
&&
.SHORT TERM /MONDAY NIGHT/...
ON MONDAY...THE SHORT WAVE TROUGH WILL DEPART IN THE MORNING.
STILL...WITH MODERATE AMOUNTS OF LOW LEVEL THETA-E IN TANDEM WITH
SLIGHTLY COOLER TEMPS ALOFT AND A WEAK SFC FRONT IN THE VCNTY...WE
COULD SEE A FEW SHOWERS DURING THE DAY...PERHAPS A THUNDERSTORM.
HOWEVER...ACTIVITY SHOULD BE FEW AND FAR BETWEEN...WITH HIGHEST
POPS ACROSS CENTRAL AND NORTHERN ZONES. HUMID CONDITIONS WILL
CONTINUE.
MUGGY AND QUIET MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
COLD FRONT APPROACHES FROM THE WEST ON TUESDAY AND WILL
SET THE STAGE FOR POSSIBLE SEVERE WEATHER. PRE-FRONTAL
TROUGH FORECAST TO PUSH IN FROM THE WEST DURING PRIME TIME
HEATING. MODERATE CAPES AND INCREASING SHEAR DURING THE
AFTERNOON AND EVENING HOURS WILL LIKELY RESULT IN MORE
ORGANIZED CONVECTION DURING THE LATE AFTERNOON AND EVENING WITH
DAMAGING WINDS THE MAIN THREAT. STRONGER CELLS MAY ALSO PRODUCE
SOME HAIL BUT FREEZING LEVELS WILL BE QUITE HIGH SO NOT LOOKING
FOR MUCH IN THE WAY OF SEVERE HAIL. WILL SEE A HOT AND MUGGY DAY
WITH HIGHS RANGING THROUGH THE 80S.
COLD FRONT WILL PUSH OFFSHORE TUESDAY NIGHT WITH CONVECTION ENDING
ACROSS THE REGION BY MIDNIGHT. HIGH PRESSURE BUILDING IN FROM THE
WEST WILL BRING CLEARING DOWNWIND OF THE MOUNTAINS. LOW TEMPS
OVERNIGHT WILL RANGE THROUGH THE 60S.
COOLER AND MUCH DRIER AIR PUSHES IN FOR WEDNESDAY AS HIGH PRESSURE
CONTINUES TO BUILD INTO THE NORTHEAST. SHOULD SEE A MOSTLY SUNNY
DAY WITH HIGHS FROM THE MID 70S TO LOWER 80S.
FAIR WEATHER WILL CONTINUE THURSDAY AND FRIDAY AS HIGH PRESSURE
CONTINUES TO BUILD SOUTH OF THE REGION FINALLY PUSHING OFFSHORE
ON FRIDAY. AFTER A STELLAR LATE SUMMER DAY ON THURSDAY...RETURN
FLOW WILL BEGIN TO PUMP WARMER AND MORE HUMID AIR BACK INTO THE
REGION ON FRIDAY. MAY SEE ENOUGH INSTABILITY CREEP INTO THE
CONNECTICUT VALLEY LATE FRIDAY TO KICK OFF AN ISOLATED SHOWER OR
THUNDERSTORM BUT THE MAJORITY OF THE FORECAST AREA WILL SEE A DRY
DAY.
RATHER STRONG LOOKING COLD FRONT FORECAST TO PUSH IN FROM THE WEST
ON SATURDAY WHICH COULD PRODUCE ANOTHER ROUND OF SEVERE
THUNDERSTORMS.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHORT TERM...LOCAL IFR IN SHOWERS AND THUNDERSTORMS THIS EVENING.
AFTER MIDNIGHT...FOG AND SOME LOW STRATUS MAY DEVELOP AND RESULT
IN LOW CONDITIONS AS WELL. MAINLY VFR EXPECTED ON MONDAY OUTSIDE
OF WDLY SCT SHOWERS.
LONG TERM...MAINLY VFR EXPECTED OUTSIDE OF ANY SHOWERS AND
THUNDERSTORMS TUE EVE/NIGHT. SOME VALLEY FOG AND COASTAL STRATUS
POSSIBLE DURING THE PERIOD LATE AT NIGHT.
&&
.MARINE...
SHORT TERM...SCA FOR THE OUTER WATERS FOR TONIGHT.
OTHERWISE...SUB-SCA CONDITIONS LIKELY THROUGH MONDAY NIGHT.
LONG TERM...SUB-SCA EXPECTED TUE THROUGH FRI.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ150-152.
&&
$$
NEAR TERM...LEGRO
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
146 PM EDT SAT AUG 30 2014
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 327 AM EDT SAT AUG 30 2014
A LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES
WILL DRAG A COLD FRONT THROUGH THE SOUTHWEST LOWER MICHIGAN
TONIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
INTO THIS EVENING AHEAD OF THE COLD FRONT. IT WILL BE WARM AND
HUMID TODAY TOO. SUNDAY WILL FOR THE MOST PART BE PARTLY CLOUDY
WITH A SLIGHT CHANCE OF AN AFTERNOON THUNDERSTORM. IT WILL
CONTINUE TO BE WARM AND HUMID. A COLD FRONT PUSHING INTO THE AREA
ON LABOR DAY WILL BRING THE RISK FOR SEVERE STORMS IN THE
AFTERNOON. WARM AND HUMID CONDITIONS WILL CONTINUE.
&&
.UPDATE...
ISSUED AT 136 PM EDT SAT AUG 30 2014
INSTABILITY WAS BUILDING SLOWLY AS THE CLOUD COVER WAS ERODING
THIS AFTERNOON. MLCAPE VALUES NEAR 500 J/KG WITH MUCAPE VALUES UP
OVER 1500 J/KG AND EFFECTIVE SHEAR VALUES ARE AROUND 35 KNOTS.
STORMS BEGINNING TO DEVELOP AND A FEW COULD CONTAIN DAMAGING WIND
GUSTS AS INSTABILITY TRIES TO INCREASE. MID LEVEL WAVE MOVING IN
FROM WI WILL HELP TO TRIGGER ADDITIONAL STORMS. CONVECTION WILL
DECREASE THIS EVENING AS THE INSTABILITY WEAKENS.
UPDATE ISSUED AT 1032 AM EDT SAT AUG 30 2014
SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS ACROSS LAKE MI. BASED
ON THE MOVEMENT...WE SHOULD SEE A PERIOD OF SUN THIS AFTERNOON.
AS A RESULT THE UPDATE FEATURES MORE SUNSHINE IN THE GRIDS. THIS
HEATING SUPPORTS THUNDERSTORMS DEVELOPING. WITH A LOW LEVEL JET
MOVING IN...THE STORMS COULD BECOME NUMEROUS. WILL KEEP THE HIGHER
POPS GOING FOR THE AFTERNOON. WILL NEED TO MONITOR THE SEVERE
POTENTIAL AS DEEP LAYER SHEAR CLIMBS ABOVE 30 KNOTS. HRRR RUC
SHOWS VERY LITTLE CONVECTION AFTER 19Z DESPITE THE ARRIVAL OF A
MID LEVEL WAVE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
WE HAVE TWO PERIODS OF CONVECTION TO WATCH IN THE SHORT TERM
FORECAST. THE THUNDERSTORMS AHEAD OF THE WEAK COLD FRONT THAT
COMES THROUGH THE AREA TONIGHT... THEN THE POSSIBLY SEVERE STORMS
ON LABOR DAY AS A STRONG JET STREAM INTERACTS WITH THE COLD FRONT
DURING MAX HEATING.
A QUICK OVERVIEW OF WHAT IS HAPPENING ON THE LARGER SCALE IS THE
SHEARING OUT SOUTHERN STREAM WAVE WE HAVE BEEN WATCHING FOR OVER
A WEEK NOW COMES THROUGH THE AREA TODAY. THE MODELS ALL SHOW THE
327 MB WAVE DEVELOPING A CLOSED UPPER LOW BY MID AFTERNOON. THE
ASSOCIATED DYNAMICS OF THE UPPER JET STREAM AND CORRESPONDING LOW
LEVEL JET WILL BRING THUNDERSTORMS TO THE AREA TODAY. THAT SYSTEM
MOVES OUT OF THE AREA LEAVING A SHORTWAVE RIDGE IN THE AREA
SUNDAY. THIS WILL RESULT IN QUIET WEATHER INTO SUNDAY NIGHT.
FINALLY A STRONG PACIFIC STORM BRINGS A NORTHERN STREAM WAVE INTO
THE AREA ON LABOR DAY. THIS WILL BRING STRONG JET DYNAMICS WITH IT
AND WILL RESULT IN A STRONG LOW LEVEL RESPONSE TO THE ASSOCIATED
COUPLED JET CORE MOVING THROUGH ON LABOR DAY.
AS FOR TODAY...THERE WILL BE TWO PERIODS OF CONVECTION. THE FIRST
WAVE IS ASSOCIATED WITH A INCREASE IN DEEP MOISTURE AND IS
LARGELY THE SYSTEM WARM FRONT COMING THROUGH. THIS HAS A LOW LEVEL
JET ASSOCIATED WITH IT AND THE AXIS OF THAT JET WILL BE FROM BTL
TO MBS BY MID MORNING. THIS WILL HELP DEVELOP STORMS OVER WESTERN
LOWER MICHIGAN THAT WILL MOVE EAST ACROSS THE STATE DURING THE
DAY. THEN THERE IS A SECOND LOW LEVEL JET ASSOCIATE WITH THE MAIN
UPPER WAVE. IT COMES ONTO SOUTHWEST MICHIGAN THIS AFTERNOON AND
INCREASE TO 35 TO 40 KNOTS NEAR LANSING BY 2 PM. THAT WILL DEVELOP
A SECOND AREA OF CONVECTION OVER WESTERN LOWER MICHIGAN THAT WILL
ALSO MOVE EAST BY LATE AFTERNOON. BY THEN MIX LAYER CAPES COULD BE
1500 J/KG SO AND THERE COULD BE AS MUCH AS 30 KNOTS OF EFFECT DEEP
LAYER SHEAR SO SOME STORMS MAY BE STRONG.
ALL OF THAT MOVES OUT LATE THIS EVENING AND SHORTWAVE RIDING
FOLLOWS SUNDAY. HOWEVER THERE IS STILL SOME INSTABILITY EVEN THOUGH
THE MID LEVELS (ABOVE 850 MB) IS RATHER DRY. I ADDED A SMALL
CHANCE OF AFTERNOON THUNDERSTORMS MOSTLY SOUTH OF I-96 IN THE
AFTERNOON FOR THAT.
THE MAIN STORY IS MONDAY WHEN THE UPPER LEVEL WAVE MOVES INTO VERY
UNSTABLE AIR. THE LOW LEVEL JET ON THE GFS IS FOCUSED ON SOUTHWEST
LOWER MICHIGAN IN THE AFTERNOON AND SHOWS OVER 3270 J/KG OF CAPE.
SO THERE IS REAL POTENTIAL FOR SEVERE STORMS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
THE MAIN FOCUS OF THE LONG TERM REMAINS ON THE SYSTEM THAT WILL BE
AFFECTING THE AREA DURING THE FIRST PART OF NEXT WEEK. THE FRONT
LOOKS TO START OUT MON EVENING TO OUR WEST YET. THIS WILL KEEP THE
THREAT OF STORMS IN THE FCST...ALTHOUGH THE THREAT OF SEVERE WEATHER
WILL BE DIMINISHING AS DIURNAL INSTABILITY WILL BE ON THE WANE A
BIT.
A RESIDUAL CHC OF SHOWERS AND STORMS WILL BE LEFT IN FOR THE DAY ON
TUE. THE FRONT LOOKS TO SINK JUST SOUTH OF THE AREA AND STALL OUT.
HOW FAR SOUTH IT STALLS IS UNCERTAIN WITH THE GFS A BIT FURTHER
SOUTH...AND THE EURO KEEPING IT CLOSER TO THE AREA. THIS FRONTAL
POSITION WILL BE IMPORTANT AS ANOTHER WAVE LOOKS TO MOVE THROUGH THE
REGION AND COULD BRING ANOTHER ROUND OF RAIN TO THE AREA ON TUE.
THE AREA SHOULD DRY OUT FOR WED WITH A RIDGE OF HIGH PRESSURE
BUILDING INTO THE AREA. THIS RIDGE WILL BE FAIRLY FLAT IN NATURE AND
WILL BE SHORT LIVED. A TROUGH EXPECTED TO COME ONSHORE OVER THE
PACIFIC NW DURING THE TUE TIME FRAME WILL PUSH A FRONTAL SYSTEM SE
INTO THE AREA LATE IN THE WEEK. PCPN CHCS WILL START ON THU AS A
WARM FRONT MOVES THROUGH THE AREA. THE COLD FRONT THEN FOLLOWS FOR
THE DAY ON FRI.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 145 PM EDT SAT AUG 30 2014
SCATTERED THUNDERSTORMS ARE EXPECTED...ESPECIALLY LATE THIS
AFTERNOON AND EARLY EVENING. THEN THE THREAT OF STORMS WILL BE
EXITING AROUND MIDNIGHT LOCAL TIME.
CONFIDENCE IN WIDESPREAD IFR LATE TONIGHT IN FOG WAS DIMINISHING
DUE TO THE ABUNDANT LOW CLOUDS THAT ARE EXPECTED TO REMAIN OVER
THE AREA. KEPT SOME IFR AROUND...BUT DID NOT HIT IT AS HARD. ANY
IFR SHOULD BE LIFTING OUT OF THE AREA BY LATE SUNDAY MORNING.
&&
.MARINE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
WAVES RUNNING 3 TO 5 FEET ALONG THE LAKESHORE. GIVEN THE VEERING
FLOW WITH GUSTS UP AROUND 25 KNOTS...HAZARDOUS CONDITIONS WILL
PERSIST INTO THE AFTERNOON. WINDS AND WAVES WILL GRADUALLY
DIMINISH LATER THIS AFTERNOON AND INTO THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 307 PM EDT FRI AUG 29 2014
HEAVY RAIN IS A RISK THROUGH SATURDAY. VERY MOIST AIRMASS WILL ADVECT
INTO MI AS PWAT VALUES GENERALLY CLIMB ABOVE 1.5 INCHES. GIVEN THE
LACK OF DIRECTIONAL SHEAR...WE COULD SEE SOME TRAINING WHICH MAY
LEAD TO THE STORMS PERSISTING. IF THIS ENDS UP OCCURRING...SOME
LOCATIONS COULD EASILY SEE OVER 2 INCHES OF RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...JK
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
136 PM EDT SAT AUG 30 2014
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 327 AM EDT SAT AUG 30 2014
A LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES
WILL DRAG A COLD FRONT THROUGH THE SOUTHWEST LOWER MICHIGAN
TONIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
INTO THIS EVENING AHEAD OF THE COLD FRONT. IT WILL BE WARM AND
HUMID TODAY TOO. SUNDAY WILL FOR THE MOST PART BE PARTLY CLOUDY
WITH A SLIGHT CHANCE OF AN AFTERNOON THUNDERSTORM. IT WILL
CONTINUE TO BE WARM AND HUMID. A COLD FRONT PUSHING INTO THE AREA
ON LABOR DAY WILL BRING THE RISK FOR SEVERE STORMS IN THE
AFTERNOON. WARM AND HUMID CONDITIONS WILL CONTINUE.
&&
.UPDATE...
ISSUED AT 136 PM EDT SAT AUG 30 2014
INSTABILITY WAS BUILDING SLOWLY AS THE CLOUD COVER WAS ERODING
THIS AFTERNOON. MLCAPE VALUES NEAR 500 JKG WITH MUCAPE VALUES UP
OVER 1500 J/KG AND EFFECTIVE SHEAR VALUES ARE AROUND 35 KNOTS.
STORMS BEGINNING TO DEVELOP AND A FEW COULD CONTAIN DAMAGING WIND
GUSTS AS INSTABILITY TRIES TO INCREASE. MID LEVEL WAVE MOVING IN
FROM WI WILL HELP TO TRIGGER ADDITIONAL STORMS. CONVECTION WILL
DECREASE THIS EVENING AS THE INSTABILITY WEAKENS.
UPDATE ISSUED AT 1032 AM EDT SAT AUG 30 2014
SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS ACROSS LAKE MI. BASED
ON THE MOVEMENT...WE SHOULD SEE A PERIOD OF SUN THIS AFTERNOON.
AS A RESULT THE UPDATE FEATURES MORE SUNSHINE IN THE GRIDS. THIS
HEATING SUPPORTS THUNDERSTORMS DEVELOPING. WITH A LOW LEVEL JET
MOVING IN...THE STORMS COULD BECOME NUMEROUS. WILL KEEP THE HIGHER
POPS GOING FOR THE AFTERNOON. WILL NEED TO MONITOR THE SEVERE
POTENTIAL AS DEEP LAYER SHEAR CLIMBS ABOVE 30 KNOTS. HRRR RUC
SHOWS VERY LITTLE CONVECTION AFTER 19Z DESPITE THE ARRIVAL OF A
MID LEVEL WAVE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
WE HAVE TWO PERIODS OF CONVECTION TO WATCH IN THE SHORT TERM
FORECAST. THE THUNDERSTORMS AHEAD OF THE WEAK COLD FRONT THAT
COMES THROUGH THE AREA TONIGHT... THEN THE POSSIBLY SEVERE STORMS
ON LABOR DAY AS A STRONG JET STREAM INTERACTS WITH THE COLD FRONT
DURING MAX HEATING.
A QUICK OVERVIEW OF WHAT IS HAPPENING ON THE LARGER SCALE IS THE
SHEARING OUT SOUTHERN STREAM WAVE WE HAVE BEEN WATCHING FOR OVER
A WEEK NOW COMES THROUGH THE AREA TODAY. THE MODELS ALL SHOW THE
327 MB WAVE DEVELOPING A CLOSED UPPER LOW BY MID AFTERNOON. THE
ASSOCIATED DYNAMICS OF THE UPPER JET STREAM AND CORRESPONDING LOW
LEVEL JET WILL BRING THUNDERSTORMS TO THE AREA TODAY. THAT SYSTEM
MOVES OUT OF THE AREA LEAVING A SHORTWAVE RIDGE IN THE AREA
SUNDAY. THIS WILL RESULT IN QUIET WEATHER INTO SUNDAY NIGHT.
FINALLY A STRONG PACIFIC STORM BRINGS A NORTHERN STREAM WAVE INTO
THE AREA ON LABOR DAY. THIS WILL BRING STRONG JET DYNAMICS WITH IT
AND WILL RESULT IN A STRONG LOW LEVEL RESPONSE TO THE ASSOCIATED
COUPLED JET CORE MOVING THROUGH ON LABOR DAY.
AS FOR TODAY...THERE WILL BE TWO PERIODS OF CONVECTION. THE FIRST
WAVE IS ASSOCIATED WITH A INCREASE IN DEEP MOISTURE AND IS
LARGELY THE SYSTEM WARM FRONT COMING THROUGH. THIS HAS A LOW LEVEL
JET ASSOCIATED WITH IT AND THE AXIS OF THAT JET WILL BE FROM BTL
TO MBS BY MID MORNING. THIS WILL HELP DEVELOP STORMS OVER WESTERN
LOWER MICHIGAN THAT WILL MOVE EAST ACROSS THE STATE DURING THE
DAY. THEN THERE IS A SECOND LOW LEVEL JET ASSOCIATE WITH THE MAIN
UPPER WAVE. IT COMES ONTO SOUTHWEST MICHIGAN THIS AFTERNOON AND
INCREASE TO 35 TO 40 KNOTS NEAR LANSING BY 2 PM. THAT WILL DEVELOP
A SECOND AREA OF CONVECTION OVER WESTERN LOWER MICHIGAN THAT WILL
ALSO MOVE EAST BY LATE AFTERNOON. BY THEN MIX LAYER CAPES COULD BE
1500 J/KG SO AND THERE COULD BE AS MUCH AS 30 KNOTS OF EFFECT DEEP
LAYER SHEAR SO SOME STORMS MAY BE STRONG.
ALL OF THAT MOVES OUT LATE THIS EVENING AND SHORTWAVE RIDING
FOLLOWS SUNDAY. HOWEVER THERE IS STILL SOME INSTABILITY EVEN THOUGH
THE MID LEVELS (ABOVE 850 MB) IS RATHER DRY. I ADDED A SMALL
CHANCE OF AFTERNOON THUNDERSTORMS MOSTLY SOUTH OF I-96 IN THE
AFTERNOON FOR THAT.
THE MAIN STORY IS MONDAY WHEN THE UPPER LEVEL WAVE MOVES INTO VERY
UNSTABLE AIR. THE LOW LEVEL JET ON THE GFS IS FOCUSED ON SOUTHWEST
LOWER MICHIGAN IN THE AFTERNOON AND SHOWS OVER 3270 J/KG OF CAPE.
SO THERE IS REAL POTENTIAL FOR SEVERE STORMS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
THE MAIN FOCUS OF THE LONG TERM REMAINS ON THE SYSTEM THAT WILL BE
AFFECTING THE AREA DURING THE FIRST PART OF NEXT WEEK. THE FRONT
LOOKS TO START OUT MON EVENING TO OUR WEST YET. THIS WILL KEEP THE
THREAT OF STORMS IN THE FCST...ALTHOUGH THE THREAT OF SEVERE WEATHER
WILL BE DIMINISHING AS DIURNAL INSTABILITY WILL BE ON THE WANE A
BIT.
A RESIDUAL CHC OF SHOWERS AND STORMS WILL BE LEFT IN FOR THE DAY ON
TUE. THE FRONT LOOKS TO SINK JUST SOUTH OF THE AREA AND STALL OUT.
HOW FAR SOUTH IT STALLS IS UNCERTAIN WITH THE GFS A BIT FURTHER
SOUTH...AND THE EURO KEEPING IT CLOSER TO THE AREA. THIS FRONTAL
POSITION WILL BE IMPORTANT AS ANOTHER WAVE LOOKS TO MOVE THROUGH THE
REGION AND COULD BRING ANOTHER ROUND OF RAIN TO THE AREA ON TUE.
THE AREA SHOULD DRY OUT FOR WED WITH A RIDGE OF HIGH PRESSURE
BUILDING INTO THE AREA. THIS RIDGE WILL BE FAIRLY FLAT IN NATURE AND
WILL BE SHORT LIVED. A TROUGH EXPECTED TO COME ONSHORE OVER THE
PACIFIC NW DURING THE TUE TIME FRAME WILL PUSH A FRONTAL SYSTEM SE
INTO THE AREA LATE IN THE WEEK. PCPN CHCS WILL START ON THU AS A
WARM FRONT MOVES THROUGH THE AREA. THE COLD FRONT THEN FOLLOWS FOR
THE DAY ON FRI.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 732 AM EDT SAT AUG 30 2014
WHILE IT SHOWERS AND ISOLATED THUNDERSTORMS WILL BE AROUND TODAY
IT WOULD SEEM THE LOW LEVELS ARE DRY ENOUGH THAT CIGS/VSBY WILL
LARGELY BE VFR. I PUT VCTS THIS AFTERNOON AS IT IS EXPECTED SOME
CONVECTION WILL BE AROUND AHEAD OF THE WEAK COLD FRONT BUT THE
ACTIVITY WILL NOT BE CONCENTRATED ENOUGH TO NAIL DOWN THE TIMING
AT THIS POINT. TONIGHT ONCE THE FRONT COMES THROUGH IT WILL STALL
AND WINDS WILL BECOME LIGHT. I WOULD EXPECT LOW CIGS AND SOME IFR
FOG TO DEVELOP TOWARD SUNRISE SUNDAY.
&&
.MARINE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
WAVES RUNNING 3 TO 5 FEET ALONG THE LAKESHORE. GIVEN THE VEERING
FLOW WITH GUSTS UP AROUND 25 KNOTS...HAZARDOUS CONDITIONS WILL
PERSIST INTO THE AFTERNOON. WINDS AND WAVES WILL GRADUALLY
DIMINISH LATER THIS AFTERNOON AND INTO THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 307 PM EDT FRI AUG 29 2014
HEAVY RAIN IS A RISK THROUGH SATURDAY. VERY MOIST AIRMASS WILL ADVECT
INTO MI AS PWAT VALUES GENERALLY CLIMB ABOVE 1.5 INCHES. GIVEN THE
LACK OF DIRECTIONAL SHEAR...WE COULD SEE SOME TRAINING WHICH MAY
LEAD TO THE STORMS PERSISTING. IF THIS ENDS UP OCCURRING...SOME
LOCATIONS COULD EASILY SEE OVER 2 INCHES OF RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 11 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1041 AM EDT SAT AUG 30 2014
LATEST UPDATE...
UPDATE/MARINE
.SYNOPSIS...
ISSUED AT 327 AM EDT SAT AUG 30 2014
A LOW PRESSURE SYSTEM TRACKING THROUGH THE NORTHERN GREAT LAKES
WILL DRAG A COLD FRONT THROUGH THE SOUTHWEST LOWER MICHIGAN
TONIGHT. PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
INTO THIS EVENING AHEAD OF THE COLD FRONT. IT WILL BE WARM AND
HUMID TODAY TOO. SUNDAY WILL FOR THE MOST PART BE PARTLY CLOUDY
WITH A SLIGHT CHANCE OF AN AFTERNOON THUNDERSTORM. IT WILL
CONTINUE TO BE WARM AND HUMID. A COLD FRONT PUSHING INTO THE AREA
ON LABOR DAY WILL BRING THE RISK FOR SEVERE STORMS IN THE
AFTERNOON. WARM AND HUMID CONDITIONS WILL CONTINUE.
&&
.UPDATE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
SATELLITE IMAGERY SHOWS DIMINISHING CLOUDS ACROSS LAKE MI. BASED
ON THE MOVEMENT...WE SHOULD SEE A PERIOD OF SUN THIS AFTERNOON.
AS A RESULT THE UPDATE FEATURES MORE SUNSHINE IN THE GRIDS. THIS
HEATING SUPPORTS THUNDERSTORMS DEVELOPING. WITH A LOW LEVEL JET
MOVING IN...THE STORMS COULD BECOME NUMEROUS. WILL KEEP THE HIGHER
POPS GOING FOR THE AFTERNOON. WILL NEED TO MONITOR THE SEVERE
POTENTIAL AS DEEP LAYER SHEAR CLIMBS ABOVE 30 KNOTS. HRRR RUC
SHOWS VERY LITTLE CONVECTION AFTER 19Z DESPITE THE ARRIVAL OF A
MID LEVEL WAVE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
WE HAVE TWO PERIODS OF CONVECTION TO WATCH IN THE SHORT TERM
FORECAST. THE THUNDERSTORMS AHEAD OF THE WEAK COLD FRONT THAT
COMES THROUGH THE AREA TONIGHT... THEN THE POSSIBLY SEVERE STORMS
ON LABOR DAY AS A STRONG JET STREAM INTERACTS WITH THE COLD FRONT
DURING MAX HEATING.
A QUICK OVERVIEW OF WHAT IS HAPPENING ON THE LARGER SCALE IS THE
SHEARING OUT SOUTHERN STREAM WAVE WE HAVE BEEN WATCHING FOR OVER
A WEEK NOW COMES THROUGH THE AREA TODAY. THE MODELS ALL SHOW THE
327 MB WAVE DEVELOPING A CLOSED UPPER LOW BY MID AFTERNOON. THE
ASSOCIATED DYNAMICS OF THE UPPER JET STREAM AND CORRESPONDING LOW
LEVEL JET WILL BRING THUNDERSTORMS TO THE AREA TODAY. THAT SYSTEM
MOVES OUT OF THE AREA LEAVING A SHORTWAVE RIDGE IN THE AREA
SUNDAY. THIS WILL RESULT IN QUIET WEATHER INTO SUNDAY NIGHT.
FINALLY A STRONG PACIFIC STORM BRINGS A NORTHERN STREAM WAVE INTO
THE AREA ON LABOR DAY. THIS WILL BRING STRONG JET DYNAMICS WITH IT
AND WILL RESULT IN A STRONG LOW LEVEL RESPONSE TO THE ASSOCIATED
COUPLED JET CORE MOVING THROUGH ON LABOR DAY.
AS FOR TODAY...THERE WILL BE TWO PERIODS OF CONVECTION. THE FIRST
WAVE IS ASSOCIATED WITH A INCREASE IN DEEP MOISTURE AND IS
LARGELY THE SYSTEM WARM FRONT COMING THROUGH. THIS HAS A LOW LEVEL
JET ASSOCIATED WITH IT AND THE AXIS OF THAT JET WILL BE FROM BTL
TO MBS BY MID MORNING. THIS WILL HELP DEVELOP STORMS OVER WESTERN
LOWER MICHIGAN THAT WILL MOVE EAST ACROSS THE STATE DURING THE
DAY. THEN THERE IS A SECOND LOW LEVEL JET ASSOCIATE WITH THE MAIN
UPPER WAVE. IT COMES ONTO SOUTHWEST MICHIGAN THIS AFTERNOON AND
INCREASE TO 35 TO 40 KNOTS NEAR LANSING BY 2 PM. THAT WILL DEVELOP
A SECOND AREA OF CONVECTION OVER WESTERN LOWER MICHIGAN THAT WILL
ALSO MOVE EAST BY LATE AFTERNOON. BY THEN MIX LAYER CAPES COULD BE
1500 J/KG SO AND THERE COULD BE AS MUCH AS 30 KNOTS OF EFFECT DEEP
LAYER SHEAR SO SOME STORMS MAY BE STRONG.
ALL OF THAT MOVES OUT LATE THIS EVENING AND SHORTWAVE RIDING
FOLLOWS SUNDAY. HOWEVER THERE IS STILL SOME INSTABILITY EVEN THOUGH
THE MID LEVELS (ABOVE 850 MB) IS RATHER DRY. I ADDED A SMALL
CHANCE OF AFTERNOON THUNDERSTORMS MOSTLY SOUTH OF I-96 IN THE
AFTERNOON FOR THAT.
THE MAIN STORY IS MONDAY WHEN THE UPPER LEVEL WAVE MOVES INTO VERY
UNSTABLE AIR. THE LOW LEVEL JET ON THE GFS IS FOCUSED ON SOUTHWEST
LOWER MICHIGAN IN THE AFTERNOON AND SHOWS OVER 3270 J/KG OF CAPE.
SO THERE IS REAL POTENTIAL FOR SEVERE STORMS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 30 2014
THE MAIN FOCUS OF THE LONG TERM REMAINS ON THE SYSTEM THAT WILL BE
AFFECTING THE AREA DURING THE FIRST PART OF NEXT WEEK. THE FRONT
LOOKS TO START OUT MON EVENING TO OUR WEST YET. THIS WILL KEEP THE
THREAT OF STORMS IN THE FCST...ALTHOUGH THE THREAT OF SEVERE WEATHER
WILL BE DIMINISHING AS DIURNAL INSTABILITY WILL BE ON THE WANE A
BIT.
A RESIDUAL CHC OF SHOWERS AND STORMS WILL BE LEFT IN FOR THE DAY ON
TUE. THE FRONT LOOKS TO SINK JUST SOUTH OF THE AREA AND STALL OUT.
HOW FAR SOUTH IT STALLS IS UNCERTAIN WITH THE GFS A BIT FURTHER
SOUTH...AND THE EURO KEEPING IT CLOSER TO THE AREA. THIS FRONTAL
POSITION WILL BE IMPORTANT AS ANOTHER WAVE LOOKS TO MOVE THROUGH THE
REGION AND COULD BRING ANOTHER ROUND OF RAIN TO THE AREA ON TUE.
THE AREA SHOULD DRY OUT FOR WED WITH A RIDGE OF HIGH PRESSURE
BUILDING INTO THE AREA. THIS RIDGE WILL BE FAIRLY FLAT IN NATURE AND
WILL BE SHORT LIVED. A TROUGH EXPECTED TO COME ONSHORE OVER THE
PACIFIC NW DURING THE TUE TIME FRAME WILL PUSH A FRONTAL SYSTEM SE
INTO THE AREA LATE IN THE WEEK. PCPN CHCS WILL START ON THU AS A
WARM FRONT MOVES THROUGH THE AREA. THE COLD FRONT THEN FOLLOWS FOR
THE DAY ON FRI.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 732 AM EDT SAT AUG 30 2014
WHILE IT SHOWERS AND ISOLATED THUNDERSTORMS WILL BE AROUND TODAY
IT WOULD SEEM THE LOW LEVELS ARE DRY ENOUGH THAT CIGS/VSBY WILL
LARGELY BE VFR. I PUT VCTS THIS AFTERNOON AS IT IS EXPECTED SOME
CONVECTION WILL BE AROUND AHEAD OF THE WEAK COLD FRONT BUT THE
ACTIVITY WILL NOT BE CONCENTRATED ENOUGH TO NAIL DOWN THE TIMING
AT THIS POINT. TONIGHT ONCE THE FRONT COMES THROUGH IT WILL STALL
AND WINDS WILL BECOME LIGHT. I WOULD EXPECT LOW CIGS AND SOME IFR
FOG TO DEVELOP TOWARD SUNRISE SUNDAY.
&&
.MARINE...
ISSUED AT 1032 AM EDT SAT AUG 30 2014
WAVES RUNNING 3 TO 5 FEET ALONG THE LAKESHORE. GIVEN THE VEERING
FLOW WITH GUSTS UP AROUND 25 KNOTS...HAZARDOUS CONDITIONS WILL
PERSIST INTO THE AFTERNOON. WINDS AND WAVES WILL GRADUALLY
DIMINISH LATER THIS AFTERNOON AND INTO THE EVENING.
&&
.HYDROLOGY...
ISSUED AT 307 PM EDT FRI AUG 29 2014
HEAVY RAIN IS A RISK THROUGH SATURDAY. VERY MOIST AIRMASS WILL ADVECT
INTO MI AS PWAT VALUES GENERALLY CLIMB ABOVE 1.5 INCHES. GIVEN THE
LACK OF DIRECTIONAL SHEAR...WE COULD SEE SOME TRAINING WHICH MAY
LEAD TO THE STORMS PERSISTING. IF THIS ENDS UP OCCURRING...SOME
LOCATIONS COULD EASILY SEE OVER 2 INCHES OF RAIN.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MIZ037-043-050-
056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...MJS
MARINE...MJS
UPDATED FOR NEW AVIATION FORECAST DISCUSSION BELOW.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 322 PM CDT FRI AUG 29 2014
AT 315PM...THERE WAS AN UPPER LEVEL TROUGH AND POTENT SHORTWAVE
OVER THE CENTRAL PLAINS. THERE WAS AN ASSOCIATED SURFACE TROUGH
OVER NORTHERN MINNESOTA AND NW MANITOBA. A WARM FRONT STRETCHED
ACROSS WEST CENTRAL AND CENTRAL WISCONSIN. MUCH OF THE NORTHLAND
HAD CLOUDY SKIES...BUT THERE WAS SOME CLEARING MOVING INTO THE FAR
SE FORECAST AREA DUE TO CLEARER SKIES FARTHER SOUTH IN THE WARM
SECTOR. SHOWERS AND STORMS WERE MOVING THROUGH THE
NORTHLAND...MAINLY THE EASTERN AND SOUTHERN FORECAST AREA.
THROUGH THIS EVENING...THE UPPER LEVEL TROUGH IN THE CENTRAL
PLAINS WILL LIFT TOWARDS WISCONSIN. THE SURFACE TROUGH WILL
CONTINUE MOVING EAST THROUGH THE FORECAST AREA...AND THE WARM
FRONT IN WISCONSIN WILL CONTINUE MOVING NORTH. THE WARM SOUTHERLY
FLOW AND MOISTURE TRANSPORT AHEAD OF THE SURFACE TROUGH WILL
CONTINUE TO BRING SHOWERS AND STORMS INTO NW WISCONSIN. THE
PRECIPITABLE WATER VALUES ARE AROUND 1.8 INCHES...SO HEAVY RAIN IS
POSSIBLE WITH ANY THUNDERSTORMS...ESPECIALLY IF THE STORMS TRAIN.
THERE IS A VERY LOW RISK OF GUSTY WINDS WITH THUNDERSTORMS IN OUR
FAR SE FORECAST AREA THROUGH THIS EVENING. THE APPROACHING WARM
FRONT AND CLEARING COULD CAUSE ENOUGH HEATING TO CAUSE ENOUGH
INSTABILITY TO RESULT IN SOME STRONG STORMS.
TONIGHT...THE PCPN CHANCES WILL GENERALLY DECREASE OVERNIGHT AS
THE MOISTURE TRANSPORT SHIFTS FARTHER EAST. A SHORTWAVE IN WESTERN
NORTH DAKOTA THIS AFTERNOON COULD BRING ISOLATED SHOWERS TO THE SW
FORECAST AREA LATE TONIGHT. THE COMBINATION OF LIGHT WIND AND HIGH
MOISTURE COULD RESULT IN PATCHY FOG FOR PARTS OF THE FORECAST
AREA.
SATURDAY...HIGH PRESSURE WILL GENERALLY KEEP THE FORECAST AREA
DRY...BUT THERE COULD BE LINGERING SHOWERS IN THE FAR SE FORECAST
AREA...AS WELL AS ISOLATED SHOWERS AND STORMS DURING THE AFTERNOON
SOUTH OF HIGHWAY 2 DUE TO WEAK CONVERGENCE NEAR A TRAILING TROUGH.
THE MORNING LOOKS CLOUDY...BUT THERE WILL LIKELY BE SCATTERING
DURING THE AFTERNOON. HIGH TEMPERATURES SHOULD BE IN THE UPPER 60S
AND LOW 70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 322 PM CDT FRI AUG 29 2014
OVERALL PATTERN REMAINS SIMILAR IN FEATURING A PROGRESSIVE FLOW
ALOFT ACROSS THE NRN CONUS THIS PERIOD. AFTER SOME INITIAL
COLLAPSE OF MID LVL HEIGHTS EARLY IN THE PERIOD A TREND TOWARDS A
LARGE BUILDING RIDGE OCCURS FROM THE SRN ROCKIES INTO THE MID
ATLANTIC. WHILE TOO EARLY TO TELL THIS MAY PLACE PARTS OF THE
REGION WITHIN A FAVORABLE CORRIDOR OF HIGH PWS AND POTENTIAL
MCS/MCC DEVELOPMENT. THE FIRST ROUND OF PRECIPITATION WILL MOVE
ACROSS THE NORTHLAND SUNDAY INTO MONDAY. A FEW DAYS OF GENERALLY
BENIGN WX SHOULD DEVELOP FROM LATE MONDAY INTO THURSDAY. THE AREA
WILL BE INFLUENCED BY A PASSING SFC HIGH THAT MOVES FROM THE CNTRL
PLAINS INTO THE OHIO VALLEY. ALTHOUGH SOME POPS ARE CURRENTLY IN
THE FCST TUESDAY THE MOISTURE/LIFT IS LIMITED AND LATER SHIFTS MAY
BE ABLE TO REDUCE/ELIMINATE WHAT IS CURRENTLY FCST. THE NEXT
CREDIBLE CHANCE FOR ORGANIZED LIFT AND MSTR TRANSPORT WILL BE LATE
IN THE WEEK AS A FRONTAL BDRY ARRIVES FROM THE NRN PLAINS. BY THAT
TIME THE AREA OF FORCING SHOULD HAVE SIGNIFICANT PWATS TO ACT
UPON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1230 AM CDT SAT AUG 30 2014
A SLOW MOVING LOW PRESSURE SYSTEM WILL CONTINUE TO IMPACT THE
NORTHLAND THROUGH THE NIGHT AND EVEN INTO SATURDAY. THE LOW WILL
GRADUALLY MOVE OFF AND THE EFFECTS WILL LESSEN ON SATURDAY. RAIN WILL
CONTINUE ACROSS NORTHERN WISCONSIN ALONG WITH A FEW THUNDERSTORMS.
IFR/LIFR AND MVFR WILL GIVE WAY TO VFR ON SATURDAY. FOG WILL
CONTINUE TO DEVELOP OVERNIGHT BUT WILL GRADUALLY LIFT SATURDAY
MORNING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 54 74 61 72 / 10 40 80 40
INL 52 73 57 71 / 10 70 70 30
BRD 58 78 60 74 / 10 70 80 20
HYR 55 79 64 75 / 10 20 80 50
ASX 53 78 63 73 / 10 10 80 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...DAP
SHORT TERM...GROCHOCINSKI
LONG TERM...CANNON
AVIATION...CLC
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
559 PM CDT SAT AUG 30 2014
.UPDATE...SENDING OUT A QUICK UPDATE TO CLEAN UP ZFP WORDING AND TO
ACCOUNT FOR CURRENT PRECIP TRENDS. WITH MUCH OF THE AREA CURRENTLY
IN A BREAK...INDICATIONS ARE THERE WILL BE NEW DEVELOPMENT LATER IN
THE EVENING. MOST RECENT HRRR RUNS HAVE SUGGESTED ACTIVITY WILL BE
FARTHER EAST THAN EARLIER ANTICIPATED...CLOSER TO THE I-55 CORRIDOR.
POPS WERE ADJUSTED ACCORDINGLY. UPDATES ARE BEING SENT AT THIS TIME.
/DL/
&&
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...LARGE CONVECTIVE BLOB
MOVING ACROSS THE CWA AT THE MOMENT LOOKS TO RAPIDLY PULL AWAY TO
THE NE DURING THE EVENING. AT PRESENT...THIS SYSTEM HAS A FEW
TROPICAL CHARACTERISTICS THAT HAVE PROVIDED SOME INTERESTING WEATHER
ACROSS THE AREA TODAY. WET BULB ZERO HEIGHTS AROUND 15KFT ALONG WITH
PW/S NEAR 2.5 INCHES SUGGESTS THAT WARM RAIN PROCESSES HAVE BEEN
DOMINANT FOR MUCH OF LA/W MS THROUGH MOST OF THE DAY. THIS STRONG
RELEASE IN LATENT HEATING HAS RESULTED IN TROFFINESS AT THE SURFACE
AND 35-45 KNOTS OF H7 FLOW TO DEVELOP WITH SOME OF THESE WIND SPEEDS
TRANSLATING TO THE GROUND IN SOME OF THE HEAVIER CONVECTION. WHERE
THE SUN WAS ABLE TO GET ON THE GROUND...IN THE EAST...BETTER
INSTABILITY AND DEEPER CONVECTION HAS DEVELOPED WITH MORE ROBUST
UPDRAFTS AND LIGHTNING.
ALTHOUGH CONVECTION LOOKS TO REMAIN OVER THE AREA FOR A PORTION OF
TONIGHT...DECIDED NOT TO INCLUDE A LIMITED THREAT OF FLOODING OR
SEVERE AS THAT THREAT WILL QUICKLY WANE AS THE SYSTEM PULLS AWAY.
WHILE MID LEVEL RIDGING WILL TAKE HOLD ACROSS THE LOWER CONUS
THROUGH THE FIRST PART OF THE WEEK...WEAK CYCLONIC SHEAR AXIS LOOKS
TO REMAIN OVER THE ARKLAMISS AT LEAST THROUGH MONDAY. THIS COMBINED
WITH PW/S NEAR 2 INCHES WILL CONTINUE TO ALLOW ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP ALONG WITH THE BUILDING HEAT. LOWER 90S
PREVALENT SUNDAY WILL BE REPLACED BY MID 90S MONDAY./26/
.LONG TERM...TUESDAY THROUGH NEXT SATURDAY...NEAR TO SLIGHTLY ABOVE
NORMAL TEMPERATURES IN THE LOW TO MID 90S AND TYPICAL 20-30%
AFTERNOON CHANCES OF SHOWERS/STORMS THROUGH MOST OF THE WEEK AS A
HIGH PRESSURE RIDGE BUILDS OVER THE SE/CENTRAL CONUS.
DESPITE LOW-LVL HIGH PRESSURE AXIS AND SLOWLY BUILDING HEIGHT
INFLUENCE OVER REGION MOST OF THE WEEK, PWATS WILL REMAIN ELEVATED
/NEAR 2"/ AND COMBINED WITH DAILY AFTERNOON INSTABILITY /2000 J/KG+/,
ISOLATED/SCATTERED SHOWERS/STORMS WILL BE LIKELY. OVERALL COVERAGE
WONT BE GREAT BUT FEEL BEST COVERAGE WILL BE IN S/SE/E WHERE SEA-
BREEZE CONVERGENCE AND HIGHEST PWATS WILL EXIST. HEAT INDICES MONDAY
AND TUESDAY SHOULD REACH INTO THE LOW 100S FOR A FEW HOURS WITH LOWS
ONLY FALLING INTO THE LOW TO MID 70S THROUGH MUCH OF THE WEEK.
ON TUESDAY...A SLIGHTLY STRONGER S/WV TROUGH ACROSS THE CORN BELT
WILL ATTEMPT TO BRING A BOUNDARY SOUTH TOWARDS THE REGION BUT FEEL
IT STAY NORTH AND THUS KEPT POPS/SHOWERS OUT OF FORECAST FOR
NORTHERN AREAS. FOR WEDNESDAY THROUGH FRIDAY...RIDGING WILL REMAIN
OVER AREA AND STRENGTHEN SLIGHTLY BUT SEA-BREEZE INITIATED AND
DIURNAL ACTIVITY SHOULD CONTINUE TO BE A GOOD POSSIBILITY EACH DAY.
BY SATURDAY, THE RIDGING SLIPS FARTHER WEST AND PLACES REGION IN
SLIGHTLY GREATER N/NE FLOW THAT COULD ENHANCE SHOWER COVERAGE
POSSIBILITIES. /ALLEN/
&&
.AVIATION...RAIN COVERS MOST OF THE AREA WITH SOME EMBEDDED
THUNDERSTORMS. RAIN WAS TAPERING OFF FROM THE SOUTHWEST AND SHOULD
BE ENDING FOR GLH SHORTLY. WILL HAVE TO ADJUST THE OTHER SITES TO
END RAIN A LITTLE SOONER. WILL ALSO KEEP FOG BEFORE MIDNIGHT
EVERYWHERE. GUIDANCE SHOWS WINDS CONTINUING AROUND 10 KTS...BUT MUCH
OF THE AREA WAS LIGHT AND VARIABLE. WILL GO WITH THE LIGHTER WINDS
FOR THE EVENING./7/
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
DL/26/7/ALLEN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
1004 AM CDT SAT AUG 30 2014
.UPDATE...OTHER THAN MOVING UP THE ONSET OF WIDESPREAD RAIN...MADE NO
OTHER CHANGES TO CURRENT FORECAST. CURRENT SURFACE ANALYSIS SHOWING
WIDESPREAD WARM TROPICAL RAINS SPREADING NORTH ACROSS NE LA/SW MS.
VERY LITTLE LIGHTNING WITH THIS AREA...PW/S NEAR 2.4 INCHES AND WET
BULB ZERO HEIGHTS AROUND 15KFT SUGGEST THAT THESE PROCESSES WILL
CONTINUE WITH HIGH PRECIPITATION EFFICIENCY AND UNDERESTIMATED RADAR
AMOUNTS.
KJAN 12 UA DATA SHOWING LAYER OF 30-40KNOT WIND FLOW BETWEEN
5 AND 20KFT. LATEST HRRR DATA IS IN AGREEMENT WITH OVERNIGHT
FORECASTERS ASSESSMENT OF A WIND THREAT TODAY IN ITS ILLUSTRATION OF
SHORT BOWING SEGMENTS IN THE FORECAST REFLECTIVITY...AS WELL
AS...FORECAST WIND GUSTS OF 30-50 KNOTS WITH THE MORE ROBUST
CONVECTION THIS AFTERNOON./26/
&&
.AVIATION...RAIN WILL BE A MORE HIT OR MISS FOR THE EASTERN AREAS
THROUGH TONIGHT. CLOUDS WERE DISSIPATING FOR HBG...GTR AND MEI. AT
THIS TIME...EXPECTING SCT-BKN CLOUDS WITH CEILINGS ABOUT 3000FT.
THUNDERSTORMS MAY DEVELOP AFTER 18Z...SO INTERMITTENT LOW CLOUDS AND
HEAVY RAIN WILL BE POSSIBLE. MAY ADD SOME TEMPO GROUPS FOR RAIN
THROUGH 3Z. GLH WILL LIKELY HAVE RAIN THROUGH THE EVENING...WITH
SOME SHORT BREAKS. EXPECTING RAIN AND/OR FOG TO MAINTAIN MVFR
CONDITIONS THROUGH MUCH OF THE FORECAST PERIOD. THROUGH THE
AFTERNOON AND EVENING LOW CLOUDS AND HEAVY RAIN MAY BRIEFLY LEAD TO
LIFR...MAYBE IFR CONDITIONS. GWO...HKS...JAN WILL SEE MORE
WIDESPREAD RAIN AFTER 18Z. WILL CONTINUE WITH VCTS...ESPECIALLY FOR
JAN/HKS BY LATE AFTERNOON. MVFR/LIFR CONDITIONS WILL BE LIKELY WITH
PERIODS OF HEAVY RAIN AND LOW CLOUDS. WILL ADD PATCHY FOG AND
STRATUS TO ALL SITES FROM 9-12Z. /7/
&&
.PREV DISCUSSION... /ISSUED 336 AM CDT SAT AUG 30 2014/
SHORT TERM...ACTIVE WEATHER DAY ON TAP AS HIGHLY MOIST AIRMASS WILL
FUEL SHRA/TSRA TODAY AS A DISTURBANCE LIFTS NORTHWARD OUT OF THE
NORTHER GULF AND S-CENTRAL SECTIONS OF LA. RECENT DAYS WE HAVE BEEN
ADVERTISING THE POTENTIAL FOR LOCALLY HEAVY RAINFALL AND SOME
POTENTIAL FOR FLASH FLOODING. THIS RISK STILL EXISTS AS EFFICIENT
RAINS WILL BE POSSIBLE AS FORCING FOR ASCENT WILL MAKE THE MOST OF
THE 2.2-2.4 IN PW AIRMASS. HOWEVER...AN ADDITIONAL THREAT FOR GUSTY
AND POSSIBLY DAMAGING WINDS EXISTS AS WELL. THE REASON FOR THIS NEW
THREAT RESIDES IN THE INCREASED FLOW BETWEEN THE 2-12 KFT LAYER.
NEARLY ALL GUIDANCE INDICATES THIS LAYER WILL CONTAIN 30-40 KTS OF
FLOW. WHILE HEATING TODAY WILL BE LIMITED AND THE THERMODYNAMIC
PROFILE WILL BE QUITE TAME...MID/UPPER 80S DEGREE TEMPS WILL SUPPORT
SBCAPE NEAR 2000 J/KG AND THIS WILL BE MORE THAN ENOUGH ENERGY TO
SUPPORT DEEP CONVECTION (ESP WITH THE DISTURBANCE PROVIDING STRONG
FORCING). FURTHERMORE...ORGANIZING CONVECTION WILL BE ABLE TO
UTILIZE THE INCREASED FLOW TO ORGANIZE COLD POOLS. IF ANY COLD POOL
ORGANIZES IN A FASHION WHERE IT MOVES IN TANDEM WITH THE FLOW BELOW
12KFT (WHICH LOOKS TO BE IN A NNE DIRECTION) BOWING SEGMENTS WILL BE
POSSIBLE AND LIKELY EFFICIENTLY BRING DOWN THE STRONGER WINDS ALOFT. IN
TURN...THIS WILL INCREASE THE WIND DAMAGE POTENTIAL. IT IS ALSO WORTH
NOTING THAT THE INCREASED FLOW WILL ALSO INCREASE THE LOW LEVEL
HELICITY TO VALUES THAT COULD SUPPORT A BRIEF TORNADO. WHILE THIS IS
NOT A PRIMARY THREAT...IT CAN`T BE RULED OUT. DUE TO ADDED
RISKS...WILL INTRODUCE A LIMITED SVR RISK FOR DAMAGING WINDS. AS FOR
A LOCATION...MOST OF THE AREA WILL HAVE A RISK...THE EXCEPTIONS LOOK
TO THE BE THE FAR SW AND THE I-59 CORRIDOR. BEST TIMING WOULD BE FROM
11AM TO 5PM. THE HWO/GRAPHICS WILL HIGHLIGHT THE TIMING AND THREAT
AREA.
AS FOR OTHER FORECAST ELEMENTS (POPS AND WEATHER)...GUIDANCE POPS
WERE HIGHER FROM THE PREV RUNS AND I FOLLOWED THOSE HIGH VALUES AND
INCREASED SOME LOCATIONS TO STAY IN LINE WITH PREV FORECASTS. THE
MAIN TIMING FOR THIS ACTIVITY WAS ADJUSTED...THE SW LOOKS TO BE THE
AREA THAT GETS IT FIRST AND EARLIEST WITH THE REMAINDER OF THE AREA
SOMETIME BETWEEN LATE MORNING AND LATE AFTERNOON. FOR THIS
EVE/OVERNIGHT...MUCH MORE OF TRICKY FORECAST EXISTS FOR TONIGHT. IT
SEEMS LIKE THERE WILL BE A LULL PERIOD FROM LATE AFTERNOON INTO MOST
OF THE EVE...THEN ACTIVITY COULD PICK UP AFTER MIDNIGHT OVER THE NW/N
AREAS. THE S HALF LOOKS TO SEE LESS ACTIVITY THAN PREV EXPECTED AS
DRIER AIR MOVES NORTHWARD IN THE WAKE OF THE MAIN S/WV.
SUNDAY LOOKS TO BE LESS ACTIVE AS WELL THANKS TO THE DRIER AIR
MOVING UP FROM THE S/SE AROUND THE EVOLVING RIDGE. STILL...ENOUGH
MOISTURE WILL EXIST FOR SOME ISO/SCT ACTIVITY. THE GFS WAS REALLY LOW
WITH POPS AND I USED A BLEND OF THE GFS/EURO FOR THE POP FORECAST.
WITH LESS PRECIP AROUND...LOOK FOR WARMER TEMPS (90-95). /CME/
LONG TERM...MONDAY THROUGH NEXT SATURDAY
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES IN THE LOW TO MID 90S AND
TYPICAL 20-30% AFTERNOON CHANCES OF SHOWERS/STORMS THROUGH MOST OF
THE WEEK AS A HIGH PRESSURE RIDGE BUILDS OVER THE SE/CENTRAL CONUS.
THE CURRENT SYSTEM RESPONSIBLE FOR ELEVATED RAIN CHANCES THIS
WEEKEND WILL PULL OFF TO THE NE BY LABOR DAY AND A SUBTROPICAL H7-H5
RIDGE LOOKS TO BUILD IN FROM THE ATLANTIC WHILE THE NRN STREAM FLOW
BECOMES MOSTLY ZONAL. DESPITE LOW-LVL HIGH PRESSURE AXIS AND SLOWLY
BUILDING HEIGHT INFLUENCE OVER REGION MOST OF THE WEEK, PWATS WILL
REMAIN ELEVATED /NEAR 2"/ AND COMBINED WITH DAILY AFTERNOON
INSTABILITY /2000 J/KG+/, ISOLATED/SCATTERED SHOWERS/STORMS WILL BE
LIKELY. OVERALL COVERAGE WONT BE GREAT BUT FEEL BEST COVERAGE WILL
BE IN S/SE/E WHERE SEA-BREEZE CONVERGENCE AND HIGHEST PWATS WILL
EXIST. HEAT INDICES MONDAY AND TUESDAY SHOULD REACH INTO THE LOW
100S FOR A FEW HOURS WITH LOWS ONLY FALLING INTO THE LOW TO MID 70S
THROUGH MUCH OF THE WEEK.
ON TUESDAY, A SLIGHTLY STRONGER S/WV TROUGH ACROSS THE CORN BELT
WILL ATTEMPT TO BRING A BOUNDARY SOUTH TOWARDS THE REGION BUT FEEL
IT STAY NORTH AND THUS KEPT POPS/SHOWERS OUT OF FORECAST FOR
NORTHERN AREAS. FOR WEDNESDAY THROUGH FRIDAY, RIDGING WILL REMAIN
OVER AREA AND STRENGTHEN SLIGHTLY BUT SEA-BREEZE INITIATED AND
DIURNAL ACTIVITY SHOULD CONTINUE TO BE A GOOD POSSIBILITY EACH DAY.
BY SATURDAY, THE RIDGING SLIPS FARTHER WEST AND PLACES REGION IN
SLIGHTLY GREATER N/NE FLOW THAT COULD ENHANCE SHOWER COVERAGE
POSSIBILITIES. /ALLEN/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 88 73 93 74 / 87 37 22 7
MERIDIAN 90 72 93 72 / 71 27 19 7
VICKSBURG 85 73 92 72 / 96 40 25 7
HATTIESBURG 91 75 96 74 / 74 19 12 13
NATCHEZ 85 73 92 74 / 92 30 18 12
GREENVILLE 84 73 91 73 / 98 60 39 6
GREENWOOD 86 74 92 73 / 96 58 39 6
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1048 PM CDT Sun Aug 31 2014
.MESOSCALE DISCUSSION...
Issued at 1034 PM CDT SUN AUG 31 2014
Line of thunderstorms generally steady state or weakening as they
move through eastern Kansas and western Missouri. Wind reports along
the edge of the line have ranged between 40 and 50 mph, although its
possible that there could continue to be an isolated 60 mph wind gust
or two along the leading edge of the line and/or any associated
outflow. MLCAPE values have dwindled down to around 1000 to 1500 J/kg
with MLCIN values climbing to around 150 J/kg, perhaps indicating
that existing activity is becoming more elevated as the boundary
layer cools. Surface winds in front of the line continue to be backed
to the south and gusty to around 20 mph, resulting in decent SRH
values (0-1 km of 250 m2/s2). Bottom line, with CIN values increasing
the severe threat is generally winding down, but other convective
parameters are concerning enough to warrant a continued threat for
isolated severe winds through the next several hours.
Precipitable water values of near 1.5 - 2.0 inches will keep the
heavy rain and flooding threat a concern through the overnight hours,
especially as the thunderstorm complex moves through the KC metro.
The ongoing storm activity will continue to be fed by a strong low
level jet, which will continue the storm activity. Will continue to
watch the potential for flooding through the night.
&&
.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 357 PM CDT SUN AUG 31 2014
Afternoon water vapor imagery showing long advertised Pacific trough
digging into the central Plains this afternoon...with strong
shortwave energy now seen entering western Nebraska. Strengthening
wind fields along the southern edge of this feature have advected
Mexican Plateau air /i.e. elevated mixed layer/ east across the
central/southern Plains as seen on the latest 7.4 micron water vapor
GOES sounder channel. Latest RUC analysis shows 7-500 mb lapse rates
approaching 9C/km across western Kansas and Nebraska...and fcst
models suggest this mid-level airmass will continue tracking east
into our region overnight. Along the surface...latest analysis shows
a developing leeside low across southeastern Colorado...with a
northward extending frontal boundary draped across the Plains which
then joins the main area of low pressure now found along the
Minnesota/Manitoba border. With time this evening...aforementioned
boundary will progress eastward as upstream troughing continues to
settle into the central and southern Plains. Airmass ahead of both
the cold front and upper wave continues to destabilize with latest
SPC meso graphics yielding as much as 3500 joules of MLCAPE between
KC and Topeka. Most importantly however...deep layered shear will
continue increasing as well as mid- level wind max moves into the
area overnight. All said...ingredients appear to be coming together
for a fairly active evening and overnight period.
Latest radar trends now showing developing cells across north-central
Kansas along the previously mentioned frontal boundary. Storms
should continue to fire this afternoon before gradually spreading east
through the early evening and overnight. As has been advertised in
recent days quite well by numerical models...isolated convection to
our west and north will likely congeal into a forward propagating MCS
this evening just before it enters northwestern Missouri. As this
occurs...deep layered shear will continue to strengthen as a low-
level jet increases to nearly 50 kts directly overhead. This poses
two potential issues for our region:
1) Maintenance of ongoing severe weather as cold pool continues to
track southeast with time into northwest Missouri/northeast Kansas
2) Increasing likelihood for developing heavy rain/possible flooding as
low-level jet ascends any convectively generated cold pools
The above said...main concerns severe-wise for our area will remain
strong damaging winds as cold pool for developing MCS tracks south
and east with time. Current thinking is damaging wind potential will
gradually decrease as storms approach the greater KC area...however
cannot rule out strong gusts in and around the metro during the late
evening hrs. Additionally...a low-end tornado threat does exist across
far northwest Missouri as strong updrafts continue to tilt horizontal
vorticity into the vertical along the leading edge of the cold pool
as it tracks south and east with time. For now...agree completely with
where SPC has the highest tornado threat /NW MO/ as further progress
to the south and east will likely result in a less favorable
environment due to nocturnal cooling/low-level stabilization effects.
In terms of hydro concerns...have elected to go with a flash flood
watch for much of northwest MO/northeast Kansas as potential exists
for training convection if an outflow boundary lays out across
central Missouri. As alluded to above...strength of developing low-
level jet is a little concerning especially when PWAT values are
expected to increase to anywhere between 2-3 standard deviations
above normal as main front approaches. HPC QPF shows a 2+ inch
bullseye directly west of KC which appears to be in favor of
developing training after midnight. Would rather play it safe hence
the current flash flood watch which runs from 2z this evening through
15z Monday morning.
Front to slowly settle south of the region during the early morning
hrs. Another round of strong to severe storms is possible on
Monday...primarly south of the the greater KC area as daytime
heating combines with still impressive wind fields aloft. For
tomorrow...more optimal timing may support isolated supercell
structures as opposed to tonight/s linear activity. Regardless...have
maintained likely pops for most areas south of I-70 during the
afternoon hrs.
Front to clear the area tomorrow night which should support a mostly
dry Tuesday. Front slowly expected to lift north as a warm front
through the day on Wednesday but minimal impacts expected as no
significant features are at play to enhance upward vertical motion.
Temps by then should begin to rise with low to mid 90s possible
Wednesday afternoon as southerly flow reinvades the area.
.LONG TERM...(Wednesday Evening through Sunday)
Issued at 357 PM CDT SUN AUG 31 2014
A little bit of everything during the extended portion of the
forecast. Storms early Wednesday, followed by a return of hot and
humid air until a cold front and more storms on Friday, then finally
some fall-like weather over the weekend.
Medium range models all on the same page with the overall pattern.
Mid-week zonal flow backs to the southwest in response to an upper
trough tracking east from the Northern Rockies through the Upper MS
Valley by Friday.
Elevated convection associated with a northward returning warm front
will affect the CWA early Wednesday followed by hot and humid air
spreading back into the region. This will likely last into Friday
when the southern extension of the Northern Plains upper trough
forces a cold front south and through the Mid MO River Valley by
Saturday morning. Moderately strong and broad area of high pressure
expanding southward will bring some much needed relief from the high
humidities.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 654 PM CDT SUN AUG 31 2014
Forecast is still on track for a line of thunderstorms to move
through each terminal over the next several hours. The line will be
approaching from the west/northwest, so KSTJ will be affected
earliest in the forecast period, with KMCI and KMKC shortly
following. The probability for severe weather is marginal at this
point, but these storms could bring gusty winds and heavy rain to the
terminals through the late evening and overnight period. The best
window for heavy rain and strong winds will only be a couple hours,
but light rain with occasional/frequent lightning will follow the
main punch and last through the night time hours before clearing out
by early Monday morning. Thereafter models hinting at some MVFR CIGs
through most of the day on Monday before becoming VFR by late
morning/early afternoon.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...FLASH FLOOD WATCH until 10 AM CDT Monday FOR KSZ025-102>105.
MO...FLASH FLOOD WATCH until 10 AM CDT Monday FOR MOZ001>005-011>014-
020>022-028>030-037.
&&
$$
MESOSCALE...Leighton
SHORT TERM...32
LONG TERM...MJ
AVIATION...Leighton
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
909 PM CDT Sun Aug 31 2014
.UPDATE:
Issued at 905 PM CDT Sun Aug 31 2014
Progressive UA trof and associated cold front, as well as outflow
boundaries produced by intense convection so far this evening,
should cause convection stretching from western Iowa to central KS to
push across the NW half of our FA overnight. Rough timing based
on extrapolation of upstream radar data suggests leading edge of
precip moving into the Edina area by 05z/midnight. While we are
missing much of today`s explicit guidance, from the data that is
available believe that the latest HRRR output has a best handle on
overnight trends in two aspects...being faster with the eastward
progression and suggesting that some precip may be knocking on the
western door of the STL metro by daybreak, and secondly more of a
focus on late night/predawn convection over eastern KS/W MO where
there should be good cold pool/low level jet interaction which
should focus the most robust convection in this area.
Forecast inherited from dayshift already trended specifics towards
the trends mentioned above, so going forecast looks quite good and
only minor adjustments needed to speed up onset of higher PoPs by
1-2 hours. If HRRR scenario does pan out I`m not too certain
about how much of a severe weather threat will reach our area, but
as mentioned by day shift there will likely be at least some
impact from upstream outflows that propagate east and produce
gusty winds.
Specific trends for Labor Day and Monday night...including the
potential for severe weather and heavy rain...will largely hinge on
how convection evolves across the region during the predawn hours
and into Monday morning; specifically how long the early morning
convection lingers and where the associated outflow boundary will be
located during the afternoon. While there is still quite a bit of
uncertainty on how the convection will evolve, it certainly appears
that outdoor plans may be altered in many areas due to the
weather.
Update will be issued as soon as 02x surface data can be ingested
and assimilated into database.
Truett
&&
.SHORT TERM: (Through Late Tonight)
Issued at 350 PM CDT Sun Aug 31 2014
Isolated to widely scattered thunderstorms over southeast portions
of the CWFA should dissipate fairly quickly this evening. Until
then, locally heavy downpours will continue over parts of the
eastern Ozarks. Attention turns to tonight as a strong shortwave
will move from eastern Wyoming into the eastern Nebraska/northwest
Missouri. An MCS is expected to develop ahead of it on the nose of
a 40kt low level jet over the eastern Plains. The model consensus
keeps the vast majority of the precipitation over western/north
central Missouri tonight. However, it does look like the leading
edge will nose into central and northeast Missouri between 08Z and
12Z. Not sure how much of the strength of the storms by that
point. Current thinking is that the cold pool may outrun the best
forcing causing the MCS to weaken as it moves east. This scenario
would have the rain moving into western portions of the CWFA between
08Z and 10Z. There may be some gusty winds as the outflow moves
through, but the most significant impact would likely be locally
heavy rain; and that looks more likely over western Missouri than in
central Missouri.
Carney
.LONG TERM: (Monday through Next Sunday)
Issued at 350 PM CDT Sun Aug 31 2014
We will see a break in what has been a hot pattern for us this past
week, as the upper level ridge breaks down, thanks to a pair of
decently strong shortwave TROFs. Much of the energy from these
shortwaves will pass us to the north, but nevertheless, we are
expecting high probabilities of rain from both of these systems
because of either a favorable position of the low level jet or
synoptic front and a very moist, deep warm-cloud atmosphere.
The first system is expected to be ongoing early Monday morning for
areas north and west of STL metro while in a slowly weakening
state. This rain is expected to reach the STL metro area before
dissipating or scattering out, with an anticipated boundary setup
near or just south of the I-70 corridor for new development in the
afternoon. There is also some potential for scattered development
Monday afternoon further north and west near the synoptic front in
northern MO and central IL.
The second system on Monday night should make more of a pass to the
south and interact with the synoptic front now deeper into our
region and favorable axis of the low level jet. In addition, there
is potential for localized heavy rainfall with PWs of around 2
inches and warm-cloud depths in excess of 4km and training storms.
The front is then expected to stall over southern MO Tuesday before
pushing north as a warm front on Wednesday with persistent, but
lesser, chances for storms.
While the humidity air never really goes away thru late week, it
should be just cool enough to prevent any dangerous heat and
humidity conditions until perhaps when the warm front pushes thru
Wednesday and into Friday.
A period of dry weather is anticipated Thursday through early Friday
with a warm-sector setup, with the next, and what looks to be much
stronger, cold front pushing thru late Friday thru early Saturday.
Increased chances for rain will return with the front with all early
indications showing a cool and dry period next weekend for most
areas.
TES
&&
.AVIATION: (For the 00z TAFs through 00z Monday Evening)
Issued at 533 PM CDT Sun Aug 31 2014
Could not rule out an isolated shower/storm in the St Louis metro
area until 02Z this evening, but it appears that the probability
is too low to include in the tafs. Convection developing across
eastern Nebraska and north central and northeastern KS along and just
ahead of a cold front will drop southeastward into the UIN and COU
areas late tonight, and then eventually into the St Louis metro
area Monday morning as it weakens. New convectve development is
expected late Monday afternoon mainly in COU and the St Louis
metro area between the approaching cold front and an outflow
boundary left from the late night/morning storm complex. Sely
surface winds this evening will gradually veer around to a sly
direction late tonight and a swly direction on Monday.
Specifics for KSTL: Will leave the STL taf dry this evening as
at most only isolated showers are expected until sunset. Weakening
showers and storms are expected to drop southeastward into STL
area Monday morning. There will be a break in the convection with
new development of storms expected late Monday afternoon and
evening. S-sely surface winds this evening will become sly late
tonight, then increase to around 15 kts by late Monday morning
from a swly direction.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
658 PM CDT Sun Aug 31 2014
.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 357 PM CDT SUN AUG 31 2014
Afternoon water vapor imagery showing long advertised Pacific trough
digging into the central Plains this afternoon...with strong
shortwave energy now seen entering western Nebraska. Strengthening
wind fields along the southern edge of this feature have advected
Mexican Plateau air /i.e. elevated mixed layer/ east across the
central/southern Plains as seen on the latest 7.4 micron water vapor
GOES sounder channel. Latest RUC analysis shows 7-500 mb lapse rates
approaching 9C/km across western Kansas and Nebraska...and fcst
models suggest this mid-level airmass will continue tracking east
into our region overnight. Along the surface...latest analysis shows
a developing leeside low across southeastern Colorado...with a
northward extending frontal boundary draped across the Plains which
then joins the main area of low pressure now found along the
Minnesota/Manitoba border. With time this evening...aforementioned
boundary will progress eastward as upstream troughing continues to
settle into the central and southern Plains. Airmass ahead of both
the cold front and upper wave continues to destabilize with latest
SPC meso graphics yielding as much as 3500 joules of MLCAPE between
KC and Topeka. Most importantly however...deep layered shear will
continue increasing as well as mid- level wind max moves into the
area overnight. All said...ingredients appear to be coming together
for a fairly active evening and overnight period.
Latest radar trends now showing developing cells across north-central
Kansas along the previously mentioned frontal boundary. Storms
should continue to fire this afternoon before gradually spreading east
through the early evening and overnight. As has been advertised in
recent days quite well by numerical models...isolated convection to
our west and north will likely congeal into a forward propagating MCS
this evening just before it enters northwestern Missouri. As this
occurs...deep layered shear will continue to strengthen as a low-
level jet increases to nearly 50 kts directly overhead. This poses
two potential issues for our region:
1) Maintenance of ongoing severe weather as cold pool continues to
track southeast with time into northwest Missouri/northeast Kansas
2) Increasing likelihood for developing heavy rain/possible flooding as
low-level jet ascends any convectively generated cold pools
The above said...main concerns severe-wise for our area will remain
strong damaging winds as cold pool for developing MCS tracks south
and east with time. Current thinking is damaging wind potential will
gradually decrease as storms approach the greater KC area...however
cannot rule out strong gusts in and around the metro during the late
evening hrs. Additionally...a low-end tornado threat does exist across
far northwest Missouri as strong updrafts continue to tilt horizontal
vorticity into the vertical along the leading edge of the cold pool
as it tracks south and east with time. For now...agree completely with
where SPC has the highest tornado threat /NW MO/ as further progress
to the south and east will likely result in a less favorable
environment due to nocturnal cooling/low-level stabilization effects.
In terms of hydro concerns...have elected to go with a flash flood
watch for much of northwest MO/northeast Kansas as potential exists
for training convection if an outflow boundary lays out across
central Missouri. As alluded to above...strength of developing low-
level jet is a little concerning especially when PWAT values are
expected to increase to anywhere between 2-3 standard deviations
above normal as main front approaches. HPC QPF shows a 2+ inch
bullseye directly west of KC which appears to be in favor of
developing training after midnight. Would rather play it safe hence
the current flash flood watch which runs from 2z this evening through
15z Monday morning.
Front to slowly settle south of the region during the early morning
hrs. Another round of strong to severe storms is possible on
Monday...primarly south of the the greater KC area as daytime
heating combines with still impressive wind fields aloft. For
tomorrow...more optimal timing may support isolated supercell
structures as opposed to tonight/s linear activity. Regardless...have
maintained likely pops for most areas south of I-70 during the
afternoon hrs.
Front to clear the area tomorrow night which should support a mostly
dry Tuesday. Front slowly expected to lift north as a warm front
through the day on Wednesday but minimal impacts expected as no
significant features are at play to enhance upward vertical motion.
Temps by then should begin to rise with low to mid 90s possible
Wednesday afternoon as southerly flow reinvades the area.
.LONG TERM...(Wednesday Evening through Sunday)
Issued at 357 PM CDT SUN AUG 31 2014
A little bit of everything during the extended portion of the
forecast. Storms early Wednesday, followed by a return of hot and
humid air until a cold front and more storms on Friday, then finally
some fall-like weather over the weekend.
Medium range models all on the same page with the overall pattern.
Mid-week zonal flow backs to the southwest in response to an upper
trough tracking east from the Northern Rockies through the Upper MS
Valley by Friday.
Elevated convection associated with a northward returning warm front
will affect the CWA early Wednesday followed by hot and humid air
spreading back into the region. This will likely last into Friday
when the southern extension of the Northern Plains upper trough
forces a cold front south and through the Mid MO River Valley by
Saturday morning. Moderately strong and broad area of high pressure
expanding southward will bring some much needed relief from the high
humidities.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 654 PM CDT SUN AUG 31 2014
Forecast is still on track for a line of thunderstorms to move
through each terminal over the next several hours. The line will be
approaching from the west/northwest, so KSTJ will be affected
earliest in the forecast period, with KMCI and KMKC shortly
following. The probability for severe weather is marginal at this
point, but these storms could bring gusty winds and heavy rain to the
terminals through the late evening and overnight period. The best
window for heavy rain and strong winds will only be a couple hours,
but light rain with occasional/frequent lightning will follow the
main punch and last through the night time hours before clearing out
by early Monday morning. Thereafter models hinting at some MVFR CIGs
through most of the day on Monday before becoming VFR by late
morning/early afternoon.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...FLASH FLOOD WATCH through Monday morning FOR KSZ025-102>105.
MO...FLASH FLOOD WATCH through Monday morning FOR MOZ001>005-011>014-
020>022-028>030-037.
&&
$$
SHORT TERM...32
LONG TERM...MJ
AVIATION...Leighton
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1206 AM CDT Sat Aug 30 2014
.DISCUSSION...
Issued at 401 PM CDT FRI AUG 29 2014
Out of the gate this afternoon...first round of convection continuing
to track east-northeast as initial shot of vorticity and pressure
advection associated with inbound upper wave slides east across the
region. Upstream behind this afternoon/s activity...skies have
cleared and weak destabilization has occurred with latest SPC
mesoanalysis suggesting anywhere between 1000-1500 J/Kg of MLCAPE
exists across eastern KS and western MO. Heading into the late
afternoon...main concern is for redeveloping convection as next piece
of shortwave energy and associated vorticity slides over the area. As
this occurs...long-lived frontal boundary which has been in place
across the central Plains in recent days should slowly slide across
the region which should also help with possible redevelopment. Fcst
models have been playing this card quite well with latest HRRR high-
res data supporting renewed convection across eastern KS this afternoon.
For now...have advertised chc pops pretty much across the western
2/3rds of the fcst area...before gradually spreading them east during
the early overnight period. In terms of severe threats...latest
mesoanalysis shows fairly weak shear aloft. This along with a DCAPE
min/trough across our region should largely prevent widespread
severe. That said though...a few strong downbursts cannot be ruled
out if convection actually does develop.
Main front to slide through the forecast area tonight as discussed
above. This should result in a gradual decrease in storm coverage
from west to east during the early morning hrs if storms do in fact
develop. Overnight lows tonight will largely reside in the middle to
upper 60s.
By all accounts...upcoming holiday weekend shaping up to be
beautiful...at least early on that is as region will reside in a post
frontal airmass both Saturday and Sunday. Despite the fropa
tonight...limited to no cooling seeing in the 850-mb temp field thus
expect high temps in the mid to upper 80s on Saturday...and
potentially into the lower to middle 90s on Sunday as warm air
advection increases ahead of next incoming wave/front.
Much more interesting weather by Sunday night/early Monday as well
advertised longwave trough continues to dig along the Front Range. As
this occurs...cyclogenesis expected across the northern Plains with
strengthening future then expected to quickly exit into the upper
Miss Vly/western Great Lakes region by early Monday. The end result
for our area will be a slowly progressing cold front which will begin
sliding south during this period...with increasing chances for rain
from Sunday night through the Tuesday time frame. Main issue seen
from this vantage point is that this feature will likely stall
somewhere across central Missouri as it begins to interact with stout
sfc ridging in place across the lwr Miss Vly and southern Plains. A
severe wx concern initially Sunday night may quickly morph into a
hydro concern as continued moisture advection resulting from a
strengthening low-level jet of 2-3 standard deviations above normal
ascends the stalled feature and cloud layer winds remain parallel to
the front. Will have to maintain vigilance with this feature as many
locations across our northwestern zones have received heavy rainfall
in recent days. If severe wx were to develop Sunday night...bulk
shear vectors orientation parallel to the incoming front will likely
support multicell type storm morphologies...with high winds winds
posing the biggest threat before concerns change over to possible
heavy rain. That said...better frontal convergence for forced ascent
will likely remain north of our fcst area which could ultimately
limit the severe threat for our region. In any event...both flooding
and possible severe pose a risk as seen this afternoon and will
maintain mention in the HWO product for now.
Beyond this...returning southerly flow will finally lift the front
north across the region with dry weather returning in its wake by
midweek. With zonal flow expected to dominate across the lower
48...temps through the conclusion of the period should remain near or
slightly above normal.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1206 AM CDT SAT AUG 30 2014
Thunderstorms continue to percolate around the Kansas City terminals
late tonight, but this activity is not expected to last much longer.
By the time the TAF is valid expectations are that the thunderstorms
activity will have moved to the east or dissipated. Therefore, only
issue in the TAF is the potential for MVFR to IFR fog as skies clear
in the wake of the storms. Winds this morning will be light and
variable which will likely result in at least some haze. Have kept IFR
conditions in for the KSTJ terminal. Otherwise, Light winds will
remain rather variable through the day Saturday, with speeds under `10
knots expected through the day.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
DISCUSSION...32
AVIATION...Cutter
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
912 PM MDT SUN AUG 31 2014
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
A WEAK SHORT WAVE TROUGH MOVING THROUGH SASKATCHEWAN WILL CREATE
ISOLATED SHOWERS AND POSSIBLE THUNDER TONIGHT THROUGH MONDAY
MORNING. BOTH THE GFS AND THE NAM HAVE SOME DIFFICULTY IN PICKING
UP THESE SHOWERS...BUT THEY ARE EVIDENT IN THE HRRR MODEL WHICH
HAS BEEN MORE SUCCESSFUL. OTHER THAN THE ISOLATED NATURE OF THE
SHOWERS THERE WILL BE MORE CLEAR SKY THAN LAST NIGHT. WITH EVENING
WIND RAPIDLY DIMINISHING AND A CONTINUED WET GROUND...PATCHY FOG
IS POSSIBLE AGAIN TONIGHT...MAINLY NEAR THE RIVER BOTTOMS. SO
EXPANDED SLIGHTLY POPS AND WX GRIDS. SCT
PREVIOUS DISCUSSION...
SYNOPTIC SET UP...HOT HIGH PRESSURE WILL REMAIN BOTTLED UP OVER
THE DESERT SOUTHWEST. ACROSS THE NORTHWESTERN QUARTER OF THE
CONUS A LARGE TROUGH WILL MOVE THROUGH THE REGION AND SLOWLY
BROADEN.
THIS AFTERNOON THROUGH MONDAY...COOLING TROUGH INFLUENCE ON THE
UPPER ATMOSPHERE WILL KEEP THE AREA DESTABILIZED THROUGH THE
AFTERNOON HOURS TODAY AND TUESDAY ALLOWING FOR LIMITED CHANCES
FROM RAIN ACROSS THE CWA. MAIN AREAS OF FOCUS ARE ALONG THE
NORTHEASTERN CORNER OF THE CWA WHERE A PAIR OF SHORTWAVE PULSES
WILL MOVE BY AND LATCH ONTO PEAK HEATING. OVERNIGHT...A CHANCE
EXISTS FOR PATCHY FOG NEAR RIVER BOTTOMS. SLIGHT INVERSION IS
ANTICIPATED TO SET IN NEAR THE SURFACE WITH VERY LIGHT WINDS
DURING THE MID MORNING HOURS.
MONDAY NIGHT THROUGH TUESDAY...HIGH PRESSURE OVER THE DESERT
SOUTHWEST WILL EXPEND NORTH DURING THIS PERIOD AND GENERATE A
WEAK...BROAD RIDGE. AS THE RIDGE MOVES IN IS SHOULD PUSH THE
THREAT FOR SHOWERS NORTHS AND GRADUALLY WARM THE CWA UP. GAH
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
MODELS HAVE FOCUSED MORE QPF/POP ON THE CWA FOR WED AND NOT SO
MUCH FOR FRI. SURROUNDING OFFICES ALSO SAW THIS TREND...SO GRIDS
WERE ADJUSTED TOWARD THIS TREND. LOWERED HUMIDITY FOR LATE IN THE
WEEK AS WELL. TFJ
PREVIOUS DISCUSSION...
THE EXTENDED PERIOD BEGINS TUESDAY NIGHT WITH SHALLOW RIDGE IN
PLACE OVER MONTANA. THIS RIDGE WILL THEN BE AMPLIFIED SLIGHTLY
OVER EASTERN MONTANA AS AN UPPER TROUGH BEGINS TO DIG INTO THE
PAC-NW. THE TROUGH...CURRENTLY STRETCHING ACROSS THE ALEUTIAN
ISLANDS...WILL MOVE INTO WASHINGTON/ OREGON TUESDAY EVENING. THIS
QUICK MOVING WAVE SENDS A COLD FRONT ACROSS MONTANA SOMETIME
WEDNESDAY. THE EC AND GFS HAVE NOT SETTLED ON THE EXACT TIMING
YET. BUT THE FRONT SHOULD INITIATE SOME SHOWER ACTIVITY. ALTHOUGH
MODELS CARRY MOST PRECIPITATION ACROSS THE SOUTHERN CANADIAN
PRAIRIE...THE STRENGTH OF THE COLD FRONT JUSTIFIES AT LEAST SLIGHT
CHANCE POPS. 850MB TEMPERATURES OF AROUND 14C TO 16C WILL DROP TO
6C TO 8C WEDNESDAY NIGHT. THIS GENERAL COOLING WILL LAST AT LEAST
THROUGH THURSDAY NIGHT.
AS THE TROUGH MOVES EAST ACROSS THE REGION ANOTHER TROUGH SPLITS
OFF ALONG THE WEST COAST. BY FRIDAY THIS WILL PLACE THE LOCAL
REGION BETWEEN TROUGH WITH GENERALLY ZONAL FLOW ALOFT. THEN BY
FRIDAY NIGHT/SATURDAY ANOTHER STRONG WORKS ITS WAY ACROSS THE
CANADIAN PRAIRIE WHICH NUDGES ANOTHER COLD FRONT TO THE SOUTH.
THIS COULD KEEP THE LID IN TEMPERATURES FOR ANOTHER DAY. SCT
&&
.AVIATION...
VFR.
ISOLATED SHOWERS/TSTORMS ARE EXPECTED TO DISSIPATE THIS EVENING.
ANOTHER ROUND OF SHOWERS/TSTORMS WILL DEVELOP NORTH AND EAST OF A
KGGW-KGDV AGAIN MONDAY AFTERNOON.
LIGHT WINDS WILL INCREASE FROM THE WEST MONDAY AFTERNOON. TFJ/PROTON
&&
.HYDROLOGY...
FLOOD WARNINGS REMAIN IN EFFECT FOR THE LOWER MILK RIVER IN VALLEY
COUNTY AND BEAVER CREEK IN EASTERN PHILLIPS.
ON BEAVER CREEK...THE WATER LEVEL AT THE GAUGE NEAR SACO REMAINS
ABOVE THE 11 FT FLOOD STAGE...BUT CONTINUES TO SLOWLY FALL.
ON THE MILK RIVER...THE LEVELS AT TAMPICO AND GLASGOW CONTINUE TO
SHOW A SLOW FALL. WATER LEVELS AT TAMPICO SHOULD DROP BELOW FLOOD
STAGE ABOUT MONDAY AFTERNOON BUT NOT FALL BELOW FLOOD STAGE AT
GLASGOW UNTIL LATE IN THE WEEK. THE RIVER HAS FALLEN BELOW FLOOD
STAGE AT NASHUA.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BILLINGS MT
234 PM MDT SAT AUG 30 2014
.SHORT TERM...VALID FOR SUN AND MON...
SERIES OF SHORTWAVES IN THE CYCLONIC FLOW ALOFT ARE PROGRESSING
ACROSS THE FORECAST AREA THIS AFTERNOON. INITIAL SHORTWAVE IS
PUSHING ACROSS FAR EASTERN MONTANA AND WILL EXIT INTO THE DAKOTAS
LATER THIS AFTERNOON. A SECONDARY WAVE IS PUSHING INTO SOUTH
CENTRAL MONTANA OUT OF YELLOWSTONE PARK. LIGHTNING ACTIVITY HAS
BEEN MORE VIGOROUS WITH THIS WAVE ALL MORNING...EVEN BACK OVER
IDAHO EARLIER...INDICATING ENHANCED MID-LEVEL INSTABILITY. WOULD
STILL NOT RULE OUT A LINE OF THUNDERSTORMS DEVELOPING ACROSS
FALLON AND CARTER COUNTIES WITH THE INITIAL WAVE. IN
FACT...A THUNDERSTORM HAS STARTED TO DEVELOP NORTHEAST OF
GILLETTE WITH THIS LINE...AND IT REMAINS TO BE SEEN WHETHER A LINE
CAN UNZIP NORTHWARD DESPITE THE CIN THAT REMAINS IN PLACE. IF A
LINE CAN DEVELOP THERE...IT WILL PROVIDE THE BEST CHANCE AT AN
ISOLATED SEVERE REPORT BEFORE THE LINE EXITS INTO THE DAKOTAS.
THE SECONDARY WAVE IS STARTING TO DEVELOP A LINE FROM JUST SOUTH
OF RED LODGE DOWN TOWARD JACKSON WYOMING. TREND IN THE HRRR HAS
BEEN TO EVOLVE THIS LINE ACROSS BIG HORN COUNTY AND SOUTHEAST
MONTANA THROUGH THIS EVENING...WITH SOME STRONGER CELLS EMBEDDED.
MAIN THREATS WITH THIS LINE OF STORMS WILL LIKELY BE HEAVY
RAIN...FREQUENT LIGHTNING AND SMALL HAIL. WHILE WOULDNT RULE OUT
A SEVERE REPORT...ELEVATED NATURE OF THE CONVECTION BEHIND THE
SURFACE FRONT SHOULD HELP TO PRECLUDE ANY SEVERE ACTIVITY.
CYCLONIC FLOW WITH WEAK EMBEDDED SHORTWAVES WILL REMAIN IN PLACE
OVER THE FORECAST AREA THROUGH SUNDAY MORNING...THUS KEEPING AN
OVERALL WET FORECAST GOING THROUGH MID DAY SUNDAY. COULD SEE A
BREAK IN THE ACTIVITY BY SUNDAY AFTERNOON AND EVENING...BEFORE
MORE ISOLATED/SCATTERED SHOWERS DEVELOP ACROSS THE AREA MONDAY
AFTERNOON AS THE CYCLONIC FLOW REMAINS IN PLACE ALOFT.
TEMPERATURES THROUGH THIS PERIOD WILL REMAIN COOLER...WITH DAY
TIME HIGHS ONLY EXPECTED IN THE LOW 70S ON SUNDAY AND MONDAY.
CHURCH
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
EXTENDED FORECAST STARTS OFF QUIET FOR TUESDAY INTO WEDNESDAY AS MODELS
CONSISTENT WITH ZONAL DOWNSLOPE FLOW ACROSS THE AREA. CONDITIONS
BEGIN TO CHANGE LATE WEDNESDAY AS SYSTEM OVER WESTERN CANADA DROPS
SOUTH AND DEFLECTS THE FLOW OVER MONTANA TO THE SOUTHWEST
INCREASING THE CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS.
THE LATEST ECMWF AND CANADIAN SOLUTIONS DRAG THE BULK OF THE
PACIFIC SYSTEM THROUGH THE AREA ON THURSDAY WHILE THE GFS IS
SLOWER AND A BIT FURTHER NORTH WITH THIS FORCING AND THE BETTER
PRECIPITATION CHANCES. WEAK ENERGY AND GENERAL TROFINESS RESIDES
OVER THE AREA BEHIND THE SYSTEM INTO NEXT WEEKEND. SPLIT THE
DIFFERENCE BETWEEN THE MODELS ON THE TIMING OF STRONGEST FORCING
OVER THE AREA RESULTING IN THE HIGHEST PRECIPITATION CHANCES LATE
THURSDAY INTO FRIDAY...BUT IF ECMWF IS CORRECT THIS COULD BE A BIT
LATE. CONTINUED 20 TO 30 PERCENT PRECIPITATION CHANCES INTO THE
WEEKEND. TRENDED TEMPERATURES DOWN FROM WEDNESDAY INTO THE WEEKEND
WITH MID 70S WEDNESDAY DROPPING INTO THE UPPER 60S FOR THURSDAY
AND FRIDAY. CHAMBERS
&&
.AVIATION...
WIDESPREAD SHOWERS AND THUNDESTORMS WILL CONTINUE ACROSS THE
FORECAST AREA INTO THIS EVENING. THUNDERSTORM COVERAGE WILL
DECREASE OVERNIGHT TONIGHT BUT SCATTERED SHOWER ACTIVITY WILL
CONTINUE INTO TOMORROW MORNING. LOCAL MVFR CONDITIONS IN MODERATE
TO HEAVY RAIN CAN BE EXPECTED WITH THIS ACTIVITY. MOUNTAIN
OBSCURATION WILL BECOME MORE PERSISTENT THROUGH THE EVENING.
CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 054/068 051/069 050/078 054/077 050/069 049/069 050/070
64/T 22/T 10/U 11/U 22/T 33/T 33/T
LVM 046/066 043/068 043/079 046/077 043/068 044/069 045/072
63/T 22/T 10/U 12/T 23/T 33/T 33/T
HDN 054/069 051/071 051/080 053/081 051/072 051/073 050/073
55/T 22/T 10/U 11/U 12/T 33/T 33/T
MLS 056/072 052/073 052/079 054/080 053/071 053/072 052/071
44/T 12/T 10/U 01/U 12/T 22/T 22/T
4BQ 055/066 051/070 051/080 053/083 052/072 051/073 051/072
65/T 23/T 10/U 01/U 22/T 33/T 22/T
BHK 054/071 049/070 049/077 051/080 050/073 049/070 049/069
63/T 13/T 10/U 12/T 22/T 22/T 22/T
SHR 052/065 047/070 046/080 050/083 049/073 048/075 048/074
55/T 22/T 10/U 11/U 12/T 33/T 33/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1020 PM MDT Fri Aug 29 2014
.DISCUSSION...
Update forthcoming. Have made some minor adjustments to the PoP
grids for the remainder of tonight. Water vapor and IR satellite
imagery clearly show upper trof position as it approaches western
Montana. Showers and isolated thunderstorms have developed out ahead
of the trof and these continue to move across southwest Montana.
This precipitation should increase in areal coverage after midnight
and begin spreading north and east as noted by the latest RUC and
HRRR analysis. Wet and unsettled morning continues to look on track.
Temperatures look reasonable.
&&
.AVIATION...
UPDATED 0420Z.
A weather disturbance and cold front will move through the area
Saturday morning. Showers will develop ahead of the cold front over
southwest and central Montana late tonight then continue into
Saturday morning as the disturbance and cold front move through.
During the afternoon expect more showers and a few thunderstorms
near and south of a KLWT to KHLN line with scattered showers north
to near U.S. route 2. As mentioned in the previous discussion expect
generally VFR conditions with the showers/thunderstorms although can
not rule out local MVFR conditions. Showers and thunderstorms are
expected to diminish Saturday evening. Blank
&&
.PREV DISCUSSION...Issued 250 PM MDT Fri Aug 29 2014
Tonight through Sunday...Isolated showers and thunderstorm will
develop in far Southwest Montana this evening then increase in
coverage overnight. Showers and storms spread into Central Montana
by Saturday morning then continue on into Eastern Montana as an
associated upper wave moves east. A reinforcing trough swings into
the state during the afternoon with additional showers and
thunderstorms developing in Southwest and Central Montana through
the afternoon; however, only isolated showers are expected over my
northwestern zones. Conditions will improve overnight as the
trough axis moves eastward leaving a cool and slightly unsettled
airmass in place over the forecast area for Sunday. mpj
Sunday Night through Friday...Relatively quiet weather conditions
expected for first half of next week. A weak, quick-moving
shortwave trof will sweep across the state on Mon. GFS and GEM
forecast models indicate little, if any, precipitation with the trof
while the ECMWF continues to indicate broad coverage of showers
mainly over the southwest counties on Mon aftn/eve. Since a
northwest flow pattern aloft (like we`ll have on Mon) usually will
generate isolated showers with even minimal moisture and
instability, have kept in a slight chance of rain showers over the
astern third of the forecast area on Mon. Weak, transient high
pressure ridging will make for dry conditions from Tues through Wed,
with slightly warmer high temperatures (low to mid 70s) as winds
aloft transition to westerly. Stronger shortwave trof is forecast
to arrive on Thurs, though model solutions still showing some marked
run-to-run differences on the shortwave`s timing and precipitation
coverage for Thurs and Fri. General model consensus is that most of
the precipitation will occur Thur eve through midday Fri, behind a
surface cold front that tracks across the region on Thurs morning.
Some locations, especially along/south of a Helena-Lewistown line
may see rainfall totals of 0.25-0.50 inch, with lighter amounts
further north. The front will also usher in a cooler Canadian
airmass and bring snow levels down to the 6500-7500 ft range over
the central mountains and the Rocky Mtn Front.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 73 48 69 / 20 50 10 10
CTB 53 71 46 67 / 0 20 10 10
HLN 56 73 47 70 / 40 60 20 10
BZN 49 70 44 66 / 40 70 40 10
WEY 43 61 35 57 / 40 80 50 10
DLN 51 69 45 65 / 50 70 40 10
HVR 55 76 49 73 / 0 50 10 0
LWT 53 72 48 67 / 20 60 20 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
116 PM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
LOW CLOUDS TODAY AND TSTM CHANCES FOR SUNDAY/SUNDAY NIGHT (WITH
SOME SEVERE WEATHER POTENTIAL) ARE THE PRIMARY FORECAST CONCERNS.
TROUGH AXIS HAD FINALLY SHIFTED EAST OF THE AREA WITH MAIN AREA OF
PCPN EARLY THIS MORNING FROM SERN MN ACROSS ERN IA AND DOWN INTO MO.
A 70 KNOT JET MAX AT 300 MB WAS NEAR THE OR/CA BORDER AT 00Z...WHICH
WAS ASSOCIATED WITH THE NEXT UPSTREAM SHORTWAVE TROUGH. 12 HOUR
HEIGHT FALLS OF UP TO 50 METERS WERE NOTED OVER SRN BC CANADA AND
WEAKER HEIGHT FALLS EXTENDED DOWN INTO NRN CA/WRN NV. OUR AREA WILL
BE MUCH DRIER TODAY WITH SHORTWAVE RIDGING BETWEEN THE DEPARTING
SYSTEM TO OUR EAST AND THE APPROACHING SYSTEM TO OUR WEST. LOW
CLOUDS WERE OVER ERN SD AND WRN IA EARLY THIS MORNING. SOME OF THE
HIGH RESOLUTION MODELS...INCLUDING THE HRRR AND RAP SHOWED THESE
OVER THE NRN AND ERN PARTS OF THE FCST AREA THIS MORNING. WILL
GENERALLY FOLLOW THIS TREND...THEN LET THE CLOUDS BREAK UP A BIT
THIS AFTN. PREVIOUS FORECAST LOOKED GOOD AND WAS IN LINE WITH A
BLEND OF MOS...SO LOOK FOR HIGHS MAINLY AROUND 80 TO 85.
TONIGHT...CLEAR TO PARTLY CLOUDY SKIES SHOULD BE THE RULE MUCH OF
THE NIGHT WITH AN INCREASE EXPECTED OVER THE WRN PARTS OF NERN
NE LATE. MODELS ARE IN GENERAL AGREEMENT THAT THIS AREA COULD ALSO
SEE SOME TSTMS BY DAYBREAK WITH MID LEVEL MOISTURE AND LIFT. THESE
WOULD THEN LIKELY DEVELOP EWD WITH TIME THE REST OF THE DAY.
THE MAIN SHOW WILL PROBABLY WAIT UNTIL LATE AFTERNOON OR EARLY
EVENING AND BE MORE TIED TO LOW LEVEL CONVERGENCE ALONG THE
APPROACHING COLD FRONT. AGREE WITH SPC DAY 2 OTLK WHICH HAS ALL
OF OUR AREA IN A SLGT RISK. ML CAPE VALUES ARE EXPECTED TO REACH
3000 TO 4000 J/KG IN THE AFTN AND LINGER INTO THE EVENING. 0 TO
6 KM BULK SHEAR VECTORS IN COMBINATION WITH EXPECTED CAPE SHOULD
BE SUFFICIENT FOR STORM ORGANIZATION. INITIALLY DISCRETE STORMS
WILL LIKELY MERGE INTO ONE OR MORE CLUSTERS AND/OR A LINE. 21Z
SUNDAY TO 06Z MONDAY SEEMS TO BE THE MOST FAVORED TIME BASED ON
FORECAST SOUNDINGS AND OTHER CURRENT MODEL DATA. IN ADDITION TO
THE SEVERE THREAT...LOCALLY HEAVY RAIN IS PROBABLY GOING TO BE AN
ISSUE DUE TO THE RECENT ISSUES WITH SOME STREAMS/RIVERS.
STORMS COULD LINGER TOWARD 12Z MONDAY NEAR THE MO BORDER BUT THE
REST OF THE DAY SHOULD BE MAINLY DRY WITH HIGHS IN THE UPPER 70S
NORTH TO LOWER 80S SOUTH.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
MODELS AGREE ON GENERAL PATTERN BUT HAVE SOME DIFFERENCES WITH
DETAILS. NORTHWEST FLOW AT 500 MB TUESDAY SHOULD BECOME MORE ZONAL
WEDNESDAY AND THEN BECOME SOUTHWEST AS A TROUGH DIGS ACROSS THE
PACIFIC NORTHWEST LATER IN THE WEEK. DID NOT FAVOR ANY ONE MODEL
IN THIS PERIOD. THE 00Z ECMWF WAS WETTER MONDAY NIGHT FOR MOST OF
THE AREA...WHILE THE GFS WAS WETTER TUESDAY NIGHT/WEDNESDAY IN
SERN NE/SWRN IA.
HIGHS SHOULD BE MOSTLY IN THE 80S WITH SOME LOWER 90S POSSIBLE
SRN ZONES THURSDAY. A SLIGHT COOL DOWN SEEMS POSSIBLE FRIDAY INTO
SATURDAY WITH A DECENT CHANCE FOR SHOWERS/THUNDERSTORMS AS ANOTHER
FRONTAL SYSTEM MOVES THROUGH THE REGION.
&&
.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 113 PM CDT SAT AUG 30 2014
STRATUS LAYER FINALLY BREAKING UP AT KOMA AT START OF FORECAST
PERIOD. VFR CONDITIONS EXPECTED AT ALL THREE SITES THROUGH THE
REMAINDER OF THE FORECAST IN ADVANCE OF APPROACHING COLD FRONT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...FOBERT
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1236 PM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT AUG 30 2014
REMNANT CONVECTIVE DEBRIS WILL CONTINUE TO SLIDE SOUTHEASTWARD
ACROSS SW NEB THROUGH SUNRISE WHILE STRATUS CONTINUES TO DROP
SOUTHWARD ACROSS ERN SD. RAP LOW LEVEL RH PROGS WOULD SUGGEST THE
STRATUS WILL SAG TO NEAR THE NIOBRARA VALLEY BY 12-15Z OR SO AND THE
HRRR HAS LOW CLOUDS EVEN FURTHER SOUTH. HAVE ADJUSTED SKY COVER FOR
THAT. PREVIOUS FCST HAD MENTION OF FOG ALSO IN THE NERN ZONES AS A
RESULT OF PREVIOUS 24 HR RAINFALL AND BELIEVE THAT THIS WOULD ALSO
BE ALONG THE FRINGE OF LOWER CLOUDS WHICH IS A TYPICAL EVOLUTION
ANYWAY. SO HAVE LEFT THE MENTION OF FOG AS IT WAS...MORE PATCHY TWD
THE SWRN PORTION OF THE AREA...ALL OF WHICH SHOULD BURN OFF BY MID
MORNING. ON THE LARGER SCALE...A TRANSITORY UPPER RIDGE WILL
PROGRESS ACROSS THE AREA TODAY AS THE NRN STREAM REMAINS
ACTIVE...WITH LARGE SCALE SUBSIDENCE IN CONTROL THROUGH THE DAY.
NEXT LONG WAVE TROUGH IS DEVELOPING ACROSS THE PAC NW WITH A LEAD PV
ANOMALY MOVING QUICKLY ACROSS THE NRN ROCKIES TODAY. A LEE SIDE SFC
TROUGH WILL DEVELOP FROM WRN SD INTO THE TX PANHANDLE BY LATE
AFTERNOON AND THE RESPONSE WILL BE AN INCREASE OF SRLY WINDS AND
DEVELOPING THERMAL RIDGE ACROSS THE HIGH PLAINS. ON THE ERN EDGE OF
THE THERMAL RIDGE /WHICH WILL BE RETREATING NWD THROUGH THE DAY/
HIGHER DEW POINTS WILL EXIST. THERE IS WEAK CONVERGENCE ASSOCIATED
WITH THIS FEATURE AS IT RETREATS DURING THE DAY...BUT DEEP LAYER
LIFT DOES NOT LOOK EVIDENT. MAX TEMPS SHOULD CREEP A FEW DEGREES
HIGHER TODAY AS A RESULT OF THE DEVELOPING THERMAL RIDGE...MOST
NOTABLY IN THE SOUTHWEST AND EASTERN PANHANDLE.
ATTENTION THEN TURNS TO LOWERING HEIGHTS ACROSS THE NRN PLAINS SAT
NIGHT AND SUNDAY. LEAD PV ANOMALY /WHICH IS BEST DEFINED INITIALLY
BY 30.00Z GFS/ WILL APPROACH THE PANHANDLE BY LATE SAT
AFTERNOON...THOUGH WEAKENING AS IT MOVES INTO THE RIDGE POSITION.
CONVERGENCE ALONG THE LEE TROUGH IS WEAK INITIALLY BUT WILL LIKELY
PROVIDE ENOUGH LIFT ALONG WITH THE HIGHER TERRAIN FURTHER WEST TO
DEVELOP AT LEAST ISOLATED TSRA WHICH WILL MOVE EWD SAT EVE...THOUGH
LOW LEVELS WILL BE FAIRLY DRY AS SUGGESTED BY WRN FCST SOUNDINGS.
HIGH PLAINS NOCTURNAL LLJ DEVELOPS THROUGH SAT EVE WHICH WILL ADVECT
MID LEVEL INSTABILITY INTO THE CENTRAL PORTION OF THE STATE AND
SHOULD MAINTAIN ENOUGH DEEP LAYER LIFT TO SUPPORT ISOLATED TSRA INTO
THE WRN PORTION OF THE FCST AREA LATE EVE AND EARLY MORNING. NAM/GEM
AND GFS SUPPORT THIS THOUGH HIRES CAMS ARE NOT SO EAGER TO DEVELOP
PRECIP. GRIDS WILL INCLUDE ISOLATED TSRA MENTION...PROGRESSING
ACROSS THE AREA THROUGH SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT AUG 30 2014
12Z SUNDAY AND BEYOND. ZONAL UPPER LEVEL FLOW TO PREVAIL ACROSS
MUCH OF THE CONTIGUOUS 48 TO START OFF THE EXTENDED FORECAST
PERIOD...BUT THE PATTERN DOES SHIFT SLIGHTLY SOUTHWESTERLY ACROSS
THE HIGH PLAINS ON SUNDAY WITH THE APPROACH OF AN UPPER
TROPOSPHERIC NORTHERN ROCKIES SHORTWAVE. THE APPROACH OF THE
SHORTWAVE WILL ALLOW AN AREA OF SFC LOW PRESSURE AND ATTENDANT
BAROCLINIC ZONE TO MOVE EAST ACROSS THE REGION THROUGH THE DAY ON
SUNDAY...POTENTIALLY SETTING THE STAGE FOR AN ACTIVE SEVERE
WEATHER PATTERN ACROSS OUR EAST BY LATE AFTERNOON. GUIDANCE
CONTINUES TO FAVOR EAST OF A KLBF TO KANW LINE WHERE THERMAL
ADVECTION IS SHOWN AND CONVERGENCE ALONG THE BAROCLINIC ZONE WILL
BE MAXIMIZED. THE GFS...NAM...AND EC ALL SHOW CONVECTION FIRING IN
THIS AREA...SO GIVEN THE GOOD AGREEMENT OF NOT ONLY THE FINER
DETAILS BUT ALSO THE LARGER SCALE PATTERN...FELT THAT CONFIDENCE
WAS ENOUGH TO INTRODUCE LIKELY/S INTO THE FORECAST ACROSS OUR FAR
EAST /EAST OF A MAYWOOD TO NAPER LINE/...WITH SOLID CHANCE POPS
/40-50%/ FOR LOCATIONS EAST OF THE KANW TO KLBF LINE SUNDAY
AFTERNOON. THE UPPER TROPOSPHERIC FLOW REMAINS FAIRLY
PROGRESSIVE...SO STORMS SHOULD BE LARGELY REMOVED OF THE FORECAST
AREA BY 06Z MONDAY. SFC TD/S ARE PROJECTED TO REBOUND BACK INTO
THE LOWER TO MID 60S ACROSS OUR EAST AND WHEN COMBINED WITH STEEP
LOWER TO MID LEVEL LAPSE RATES WHICH PROMOTE SB POTENTIAL ENERGY
IN EXCESS OF 2500 J/KG...ROBUST UPDRAFTS ARE ANTICIPATED. DEEP
LAYER SHEAR IS SHOWN TO BE QUITE FAVORABLE FOR SEVERE
WEATHER...WITH THE MODELS PEGGING UPWARDS OF 40-50KTS 0-6KM BULK
SHEAR...LARGE HAIL WILL BE POSSIBLE. THE UPDRAFTS SHOULD QUICKLY
CONGEAL ALONG THE BAROCLINIC ZONE INTO A QUASI-LINEAR CONVECTIVE
BAND WHICH WOULD PROMOTE DAMAGING THUNDERSTORM WIND INTO THE
EVENING.
INTO EARLY NEXT WEEK...THERE REMAINS SOME DISCREPANCIES ON THE
TIMING OF THE EXITING TROUGH...MOST NOTABLY...THE EC RETAINS A PIECE
OF ENERGY WEST OF THE FORECAST AREA...BUT BRINGS IT THROUGH MONDAY
NIGHT. THE EC GENERATES LIGHT QPF ACROSS MUCH OF THE FORECAST AREA
DURING THIS TIME PERIOD. THE GFS IN COMPARISON IS DRY AND LACKS
MUCH OF THE EVIDENCE SUPPORTING THIS ADDITIONAL TROPOSPHERIC
PERTURBATION. GIVEN THE UNCERTAINTY...WENT AHEAD AND SCALED BACK
POPS MONDAY EVENING INTO EARLY TUESDAY...BUT WILL KEEP A SLIGHT
MENTION GOING.
BEYOND EARLY TUESDAY...THE CR ALLBLEND PROCEDURE PROJECTED A DRY
FORECAST THROUGH THURSDAY OF NEXT WEEK...AND THERE ARE NO ARGUMENTS
HERE AS AN OVERALL LACK OF OMEGA WOULD BE ANTICIPATED AS THE STORM
TRACK SHIFTS NORTH AND LOW AMPLITUDE RIDGING ENCOMPASSES MUCH OF THE
CONUS. LATE IN THE EXTENDED THERE MAY BE ANOTHER SHORTWAVE
IMPACTING THE CENTRAL PLAINS...HOWEVER THE MODELS SEEM TO BE BACKING
OFF THIS SOLUTION A BIT...FOCUSING THE BEST POTENTIAL WELL NORTH OF
THE CWA. WILL KEEP THE PROCEDURE UNCHANGED FOR NOW.
NOT ANTICIPATING ANY VIOLENT TEMPERATURE CHANGES THROUGH THE
EXTENDED PERIODS...BUT WITH EACH FRONTAL PASSAGE...TEMPERATURES WILL
MODERATE SOME. THE WARMEST DAY APPEARS TO COME MID-WEEK...AS HIGHS
ON WEDNESDAY ARE FORECAST TO APPROACH THE UPPER 80S TO LOWER 90S FOR
MOST LOCATIONS. OTHERWISE HIGHS IN THE 70S TO LOW TO MID 80S SHOULD
PREVAIL FOR MOST DAYS. LOWS IN THE 50S AND 60S SEEM TO BE THE NORM
OVER THE NEXT 7 DAYS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1234 PM CDT SAT AUG 30 2014
VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA THROUGH THE NEXT 24 HOURS. ISOLATED SHOWERS AND STORMS
MAY MOVE EAST OUT OF THE PANHANDLE AFTER 3Z TONIGHT...HOWEVER
LIMITED SPATIAL COVERAGE AND LOW FORECASTER CONFIDENCE DO NOT
WARRANT ANY MENTION OF -TSRA IN THE TAFS AT THIS TIME. A COLD
FRONT WILL MOVE THROUGH THE AREA TOMORROW MORNING...SWITCHING THE
WIND DIRECTION TO THE NORTHWEST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JWS
LONG TERM...JACOBS
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
637 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT AUG 30 2014
REMNANT CONVECTIVE DEBRIS WILL CONTINUE TO SLIDE SOUTHEASTWARD
ACROSS SW NEB THROUGH SUNRISE WHILE STRATUS CONTINUES TO DROP
SOUTHWARD ACROSS ERN SD. RAP LOW LEVEL RH PROGS WOULD SUGGEST THE
STRATUS WILL SAG TO NEAR THE NIOBRARA VALLEY BY 12-15Z OR SO AND THE
HRRR HAS LOW CLOUDS EVEN FURTHER SOUTH. HAVE ADJUSTED SKY COVER FOR
THAT. PREVIOUS FCST HAD MENTION OF FOG ALSO IN THE NERN ZONES AS A
RESULT OF PREVIOUS 24 HR RAINFALL AND BELIEVE THAT THIS WOULD ALSO
BE ALONG THE FRINGE OF LOWER CLOUDS WHICH IS A TYPICAL EVOLUTION
ANYWAY. SO HAVE LEFT THE MENTION OF FOG AS IT WAS...MORE PATCHY TWD
THE SWRN PORTION OF THE AREA...ALL OF WHICH SHOULD BURN OFF BY MID
MORNING. ON THE LARGER SCALE...A TRANSITORY UPPER RIDGE WILL
PROGRESS ACROSS THE AREA TODAY AS THE NRN STREAM REMAINS
ACTIVE...WITH LARGE SCALE SUBSIDENCE IN CONTROL THROUGH THE DAY.
NEXT LONG WAVE TROUGH IS DEVELOPING ACROSS THE PAC NW WITH A LEAD PV
ANOMALY MOVING QUICKLY ACROSS THE NRN ROCKIES TODAY. A LEE SIDE SFC
TROUGH WILL DEVELOP FROM WRN SD INTO THE TX PANHANDLE BY LATE
AFTERNOON AND THE RESPONSE WILL BE AN INCREASE OF SRLY WINDS AND
DEVELOPING THERMAL RIDGE ACROSS THE HIGH PLAINS. ON THE ERN EDGE OF
THE THERMAL RIDGE /WHICH WILL BE RETREATING NWD THROUGH THE DAY/
HIGHER DEW POINTS WILL EXIST. THERE IS WEAK CONVERGENCE ASSOCIATED
WITH THIS FEATURE AS IT RETREATS DURING THE DAY...BUT DEEP LAYER
LIFT DOES NOT LOOK EVIDENT. MAX TEMPS SHOULD CREEP A FEW DEGREES
HIGHER TODAY AS A RESULT OF THE DEVELOPING THERMAL RIDGE...MOST
NOTABLY IN THE SOUTHWEST AND EASTERN PANHANDLE.
ATTENTION THEN TURNS TO LOWERING HEIGHTS ACROSS THE NRN PLAINS SAT
NIGHT AND SUNDAY. LEAD PV ANOMALY /WHICH IS BEST DEFINED INITIALLY
BY 30.00Z GFS/ WILL APPROACH THE PANHANDLE BY LATE SAT
AFTERNOON...THOUGH WEAKENING AS IT MOVES INTO THE RIDGE POSITION.
CONVERGENCE ALONG THE LEE TROUGH IS WEAK INITIALLY BUT WILL LIKELY
PROVIDE ENOUGH LIFT ALONG WITH THE HIGHER TERRAIN FURTHER WEST TO
DEVELOP AT LEAST ISOLATED TSRA WHICH WILL MOVE EWD SAT EVE...THOUGH
LOW LEVELS WILL BE FAIRLY DRY AS SUGGESTED BY WRN FCST SOUNDINGS.
HIGH PLAINS NOCTURNAL LLJ DEVELOPS THROUGH SAT EVE WHICH WILL ADVECT
MID LEVEL INSTABILITY INTO THE CENTRAL PORTION OF THE STATE AND
SHOULD MAINTAIN ENOUGH DEEP LAYER LIFT TO SUPPORT ISOLATED TSRA INTO
THE WRN PORTION OF THE FCST AREA LATE EVE AND EARLY MORNING. NAM/GEM
AND GFS SUPPORT THIS THOUGH HIRES CAMS ARE NOT SO EAGER TO DEVELOP
PRECIP. GRIDS WILL INCLUDE ISOLATED TSRA MENTION...PROGRESSING
ACROSS THE AREA THROUGH SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT AUG 30 2014
12Z SUNDAY AND BEYOND. ZONAL UPPER LEVEL FLOW TO PREVAIL ACROSS
MUCH OF THE CONTIGUOUS 48 TO START OFF THE EXTENDED FORECAST
PERIOD...BUT THE PATTERN DOES SHIFT SLIGHTLY SOUTHWESTERLY ACROSS
THE HIGH PLAINS ON SUNDAY WITH THE APPROACH OF AN UPPER
TROPOSPHERIC NORTHERN ROCKIES SHORTWAVE. THE APPROACH OF THE
SHORTWAVE WILL ALLOW AN AREA OF SFC LOW PRESSURE AND ATTENDANT
BAROCLINIC ZONE TO MOVE EAST ACROSS THE REGION THROUGH THE DAY ON
SUNDAY...POTENTIALLY SETTING THE STAGE FOR AN ACTIVE SEVERE
WEATHER PATTERN ACROSS OUR EAST BY LATE AFTERNOON. GUIDANCE
CONTINUES TO FAVOR EAST OF A KLBF TO KANW LINE WHERE THERMAL
ADVECTION IS SHOWN AND CONVERGENCE ALONG THE BAROCLINIC ZONE WILL
BE MAXIMIZED. THE GFS...NAM...AND EC ALL SHOW CONVECTION FIRING IN
THIS AREA...SO GIVEN THE GOOD AGREEMENT OF NOT ONLY THE FINER
DETAILS BUT ALSO THE LARGER SCALE PATTERN...FELT THAT CONFIDENCE
WAS ENOUGH TO INTRODUCE LIKELY/S INTO THE FORECAST ACROSS OUR FAR
EAST /EAST OF A MAYWOOD TO NAPER LINE/...WITH SOLID CHANCE POPS
/40-50%/ FOR LOCATIONS EAST OF THE KANW TO KLBF LINE SUNDAY
AFTERNOON. THE UPPER TROPOSPHERIC FLOW REMAINS FAIRLY
PROGRESSIVE...SO STORMS SHOULD BE LARGELY REMOVED OF THE FORECAST
AREA BY 06Z MONDAY. SFC TD/S ARE PROJECTED TO REBOUND BACK INTO
THE LOWER TO MID 60S ACROSS OUR EAST AND WHEN COMBINED WITH STEEP
LOWER TO MID LEVEL LAPSE RATES WHICH PROMOTE SB POTENTIAL ENERGY
IN EXCESS OF 2500 J/KG...ROBUST UPDRAFTS ARE ANTICIPATED. DEEP
LAYER SHEAR IS SHOWN TO BE QUITE FAVORABLE FOR SEVERE
WEATHER...WITH THE MODELS PEGGING UPWARDS OF 40-50KTS 0-6KM BULK
SHEAR...LARGE HAIL WILL BE POSSIBLE. THE UPDRAFTS SHOULD QUICKLY
CONGEAL ALONG THE BAROCLINIC ZONE INTO A QUASI-LINEAR CONVECTIVE
BAND WHICH WOULD PROMOTE DAMAGING THUNDERSTORM WIND INTO THE
EVENING.
INTO EARLY NEXT WEEK...THERE REMAINS SOME DISCREPANCIES ON THE
TIMING OF THE EXITING TROUGH...MOST NOTABLY...THE EC RETAINS A PIECE
OF ENERGY WEST OF THE FORECAST AREA...BUT BRINGS IT THROUGH MONDAY
NIGHT. THE EC GENERATES LIGHT QPF ACROSS MUCH OF THE FORECAST AREA
DURING THIS TIME PERIOD. THE GFS IN COMPARISON IS DRY AND LACKS
MUCH OF THE EVIDENCE SUPPORTING THIS ADDITIONAL TROPOSPHERIC
PERTURBATION. GIVEN THE UNCERTAINTY...WENT AHEAD AND SCALED BACK
POPS MONDAY EVENING INTO EARLY TUESDAY...BUT WILL KEEP A SLIGHT
MENTION GOING.
BEYOND EARLY TUESDAY...THE CR ALLBLEND PROCEDURE PROJECTED A DRY
FORECAST THROUGH THURSDAY OF NEXT WEEK...AND THERE ARE NO ARGUMENTS
HERE AS AN OVERALL LACK OF OMEGA WOULD BE ANTICIPATED AS THE STORM
TRACK SHIFTS NORTH AND LOW AMPLITUDE RIDGING ENCOMPASSES MUCH OF THE
CONUS. LATE IN THE EXTENDED THERE MAY BE ANOTHER SHORTWAVE
IMPACTING THE CENTRAL PLAINS...HOWEVER THE MODELS SEEM TO BE BACKING
OFF THIS SOLUTION A BIT...FOCUSING THE BEST POTENTIAL WELL NORTH OF
THE CWA. WILL KEEP THE PROCEDURE UNCHANGED FOR NOW.
NOT ANTICIPATING ANY VIOLENT TEMPERATURE CHANGES THROUGH THE
EXTENDED PERIODS...BUT WITH EACH FRONTAL PASSAGE...TEMPERATURES WILL
MODERATE SOME. THE WARMEST DAY APPEARS TO COME MID-WEEK...AS HIGHS
ON WEDNESDAY ARE FORECAST TO APPROACH THE UPPER 80S TO LOWER 90S FOR
MOST LOCATIONS. OTHERWISE HIGHS IN THE 70S TO LOW TO MID 80S SHOULD
PREVAIL FOR MOST DAYS. LOWS IN THE 50S AND 60S SEEM TO BE THE NORM
OVER THE NEXT 7 DAYS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 638 AM CDT SAT AUG 30 2014
BIGGEST CONCERN WITH THE TERMINAL FCST INVOLVES PATCHY SHALLOW FOG
IN THE KLBF AREA THIS MORNING. VSBY AROUND THE KLBF TAF SITE IS HIGHLY
VARIABLE WITH SHALLOW AND PATCHY FOG SEEN IN OUTLYING AREA CURRENTLY...BUT
AS OF YET NOT AT THE SENSOR LOCATION. THREAT OF FOG SHOULD
DECREASE SUBSTANTIALLY THOUGH AFTER 15Z AS FULL SUNSHINE TAKES
OVER. IN ADDITION...SCT CLOUDS NEAR THE KVTN SITE THIS MORNING ARE
BELOW LOCAL ALTERNATE MINIMUMS...AND PATCHY FOG IS ALSO AN ISSUE
FURTHER NORTH NEAR THE SD BORDER. SHORT RANGE MODELS EVENTUALLY
MOVE THE CLOUDS EWD DURING THE MORNING HOURS SO AGAIN BY NOON
THESE CONCERNS SHOULD BE OVER.
WEAK AND ISOLATED CONVECTION IS POSSIBLE TONIGHT...MAINLY NEAR THE
KLBF SITE. HOWEVER CONFIDENCE IS LOW ON ANY PARTICULAR SOLUTION
WITHIN 24 HRS...AS NAM/GEM DEVELOP WEAK CONVECTION BUT HIRES
MODELS ARE GENERALLY DRY TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JWS
LONG TERM...JACOBS
AVIATION...JWS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
616 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
LOW CLOUDS TODAY AND TSTM CHANCES FOR SUNDAY/SUNDAY NIGHT (WITH
SOME SEVERE WEATHER POTENTIAL) ARE THE PRIMARY FORECAST CONCERNS.
TROUGH AXIS HAD FINALLY SHIFTED EAST OF THE AREA WITH MAIN AREA OF
PCPN EARLY THIS MORNING FROM SERN MN ACROSS ERN IA AND DOWN INTO MO.
A 70 KNOT JET MAX AT 300 MB WAS NEAR THE OR/CA BORDER AT 00Z...WHICH
WAS ASSOCIATED WITH THE NEXT UPSTREAM SHORTWAVE TROUGH. 12 HOUR
HEIGHT FALLS OF UP TO 50 METERS WERE NOTED OVER SRN BC CANADA AND
WEAKER HEIGHT FALLS EXTENDED DOWN INTO NRN CA/WRN NV. OUR AREA WILL
BE MUCH DRIER TODAY WITH SHORTWAVE RIDGING BETWEEN THE DEPARTING
SYSTEM TO OUR EAST AND THE APPROACHING SYSTEM TO OUR WEST. LOW
CLOUDS WERE OVER ERN SD AND WRN IA EARLY THIS MORNING. SOME OF THE
HIGH RESOLUTION MODELS...INCLUDING THE HRRR AND RAP SHOWED THESE
OVER THE NRN AND ERN PARTS OF THE FCST AREA THIS MORNING. WILL
GENERALLY FOLLOW THIS TREND...THEN LET THE CLOUDS BREAK UP A BIT
THIS AFTN. PREVIOUS FORECAST LOOKED GOOD AND WAS IN LINE WITH A
BLEND OF MOS...SO LOOK FOR HIGHS MAINLY AROUND 80 TO 85.
TONIGHT...CLEAR TO PARTLY CLOUDY SKIES SHOULD BE THE RULE MUCH OF
THE NIGHT WITH AN INCREASE EXPECTED OVER THE WRN PARTS OF NERN
NE LATE. MODELS ARE IN GENERAL AGREEMENT THAT THIS AREA COULD ALSO
SEE SOME TSTMS BY DAYBREAK WITH MID LEVEL MOISTURE AND LIFT. THESE
WOULD THEN LIKELY DEVELOP EWD WITH TIME THE REST OF THE DAY.
THE MAIN SHOW WILL PROBABLY WAIT UNTIL LATE AFTERNOON OR EARLY
EVENING AND BE MORE TIED TO LOW LEVEL CONVERGENCE ALONG THE
APPROACHING COLD FRONT. AGREE WITH SPC DAY 2 OTLK WHICH HAS ALL
OF OUR AREA IN A SLGT RISK. ML CAPE VALUES ARE EXPECTED TO REACH
3000 TO 4000 J/KG IN THE AFTN AND LINGER INTO THE EVENING. 0 TO
6 KM BULK SHEAR VECTORS IN COMBINATION WITH EXPECTED CAPE SHOULD
BE SUFFICIENT FOR STORM ORGANIZATION. INITIALLY DISCRETE STORMS
WILL LIKELY MERGE INTO ONE OR MORE CLUSTERS AND/OR A LINE. 21Z
SUNDAY TO 06Z MONDAY SEEMS TO BE THE MOST FAVORED TIME BASED ON
FORECAST SOUNDINGS AND OTHER CURRENT MODEL DATA. IN ADDITION TO
THE SEVERE THREAT...LOCALLY HEAVY RAIN IS PROBABLY GOING TO BE AN
ISSUE DUE TO THE RECENT ISSUES WITH SOME STREAMS/RIVERS.
STORMS COULD LINGER TOWARD 12Z MONDAY NEAR THE MO BORDER BUT THE
REST OF THE DAY SHOULD BE MAINLY DRY WITH HIGHS IN THE UPPER 70S
NORTH TO LOWER 80S SOUTH.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
MODELS AGREE ON GENERAL PATTERN BUT HAVE SOME DIFFERENCES WITH
DETAILS. NORTHWEST FLOW AT 500 MB TUESDAY SHOULD BECOME MORE ZONAL
WEDNESDAY AND THEN BECOME SOUTHWEST AS A TROUGH DIGS ACROSS THE
PACIFIC NORTHWEST LATER IN THE WEEK. DID NOT FAVOR ANY ONE MODEL
IN THIS PERIOD. THE 00Z ECMWF WAS WETTER MONDAY NIGHT FOR MOST OF
THE AREA...WHILE THE GFS WAS WETTER TUESDAY NIGHT/WEDNESDAY IN
SERN NE/SWRN IA.
HIGHS SHOULD BE MOSTLY IN THE 80S WITH SOME LOWER 90S POSSIBLE
SRN ZONES THURSDAY. A SLIGHT COOL DOWN SEEMS POSSIBLE FRIDAY INTO
SATURDAY WITH A DECENT CHANCE FOR SHOWERS/THUNDERSTORMS AS ANOTHER
FRONTAL SYSTEM MOVES THROUGH THE REGION.
&&
.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 607 AM CDT SAT AUG 30 2014
REGIONAL OBS/IR SATL INDICATING BATCH OF LLVL CIGS SITUATED OVER
ERN SD WAS GRADUALLY DRIFTING SWD INTO ERN NEB THIS MORNING. GIVEN
MOVEMENT TRENDS THE LAST SEVERAL HOURS...APPEARS THAT BRIEF PD OF
IFR CONDITIONS LIKELY THIS MORNING AT KOFK/KOMA WITH VFR
CONDITIONS THEREAFTER. FOR KLNK...EXPECT VFR CONDITIONS TO
PREVAIL THERE.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...DEE
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
335 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
LOW CLOUDS TODAY AND TSTM CHANCES FOR SUNDAY/SUNDAY NIGHT (WITH
SOME SEVERE WEATHER POTENTIAL) ARE THE PRIMARY FORECAST CONCERNS.
TROUGH AXIS HAD FINALLY SHIFTED EAST OF THE AREA WITH MAIN AREA OF
PCPN EARLY THIS MORNING FROM SERN MN ACROSS ERN IA AND DOWN INTO MO.
A 70 KNOT JET MAX AT 300 MB WAS NEAR THE OR/CA BORDER AT 00Z...WHICH
WAS ASSOCIATED WITH THE NEXT UPSTREAM SHORTWAVE TROUGH. 12 HOUR
HEIGHT FALLS OF UP TO 50 METERS WERE NOTED OVER SRN BC CANADA AND
WEAKER HEIGHT FALLS EXTENDED DOWN INTO NRN CA/WRN NV. OUR AREA WILL
BE MUCH DRIER TODAY WITH SHORTWAVE RIDGING BETWEEN THE DEPARTING
SYSTEM TO OUR EAST AND THE APPROACHING SYSTEM TO OUR WEST. LOW
CLOUDS WERE OVER ERN SD AND WRN IA EARLY THIS MORNING. SOME OF THE
HIGH RESOLUTION MODELS...INCLUDING THE HRRR AND RAP SHOWED THESE
OVER THE NRN AND ERN PARTS OF THE FCST AREA THIS MORNING. WILL
GENERALLY FOLLOW THIS TREND...THEN LET THE CLOUDS BREAK UP A BIT
THIS AFTN. PREVIOUS FORECAST LOOKED GOOD AND WAS IN LINE WITH A
BLEND OF MOS...SO LOOK FOR HIGHS MAINLY AROUND 80 TO 85.
TONIGHT...CLEAR TO PARTLY CLOUDY SKIES SHOULD BE THE RULE MUCH OF
THE NIGHT WITH AN INCREASE EXPECTED OVER THE WRN PARTS OF NERN
NE LATE. MODELS ARE IN GENERAL AGREEMENT THAT THIS AREA COULD ALSO
SEE SOME TSTMS BY DAYBREAK WITH MID LEVEL MOISTURE AND LIFT. THESE
WOULD THEN LIKELY DEVELOP EWD WITH TIME THE REST OF THE DAY.
THE MAIN SHOW WILL PROBABLY WAIT UNTIL LATE AFTERNOON OR EARLY
EVENING AND BE MORE TIED TO LOW LEVEL CONVERGENCE ALONG THE
APPROACHING COLD FRONT. AGREE WITH SPC DAY 2 OTLK WHICH HAS ALL
OF OUR AREA IN A SLGT RISK. ML CAPE VALUES ARE EXPECTED TO REACH
3000 TO 4000 J/KG IN THE AFTN AND LINGER INTO THE EVENING. 0 TO
6 KM BULK SHEAR VECTORS IN COMBINATION WITH EXPECTED CAPE SHOULD
BE SUFFICIENT FOR STORM ORGANIZATION. INITIALLY DISCRETE STORMS
WILL LIKELY MERGE INTO ONE OR MORE CLUSTERS AND/OR A LINE. 21Z
SUNDAY TO 06Z MONDAY SEEMS TO BE THE MOST FAVORED TIME BASED ON
FORECAST SOUNDINGS AND OTHER CURRENT MODEL DATA. IN ADDITION TO
THE SEVERE THREAT...LOCALLY HEAVY RAIN IS PROBABLY GOING TO BE AN
ISSUE DUE TO THE RECENT ISSUES WITH SOME STREAMS/RIVERS.
STORMS COULD LINGER TOWARD 12Z MONDAY NEAR THE MO BORDER BUT THE
REST OF THE DAY SHOULD BE MAINLY DRY WITH HIGHS IN THE UPPER 70S
NORTH TO LOWER 80S SOUTH.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 30 2014
MODELS AGREE ON GENERAL PATTERN BUT HAVE SOME DIFFERENCES WITH
DETAILS. NORTHWEST FLOW AT 500 MB TUESDAY SHOULD BECOME MORE ZONAL
WEDNESDAY AND THEN BECOME SOUTHWEST AS A TROUGH DIGS ACROSS THE
PACIFIC NORTHWEST LATER IN THE WEEK. DID NOT FAVOR ANY ONE MODEL
IN THIS PERIOD. THE 00Z ECMWF WAS WETTER MONDAY NIGHT FOR MOST OF
THE AREA...WHILE THE GFS WAS WETTER TUESDAY NIGHT/WEDNESDAY IN
SERN NE/SWRN IA.
HIGHS SHOULD BE MOSTLY IN THE 80S WITH SOME LOWER 90S POSSIBLE
SRN ZONES THURSDAY. A SLIGHT COOL DOWN SEEMS POSSIBLE FRIDAY INTO
SATURDAY WITH A DECENT CHANCE FOR SHOWERS/THUNDERSTORMS AS ANOTHER
FRONTAL SYSTEM MOVES THROUGH THE REGION.
&&
.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1153 PM CDT FRI AUG 29 2014
WITH SHOWERS DISSIPATING OVER EASTERN NEBRASKA...ONLY SCATTERED
MID AND HIGH CLOUDS ARE EXPECTED OVERNIGHT. HOWEVER AREAS OF FOG
AND STRATUS ARE EXPECTED TO FORM AFTER 08Z AT ALL TAF SITES. CIGS
BETWEEN FL005 AND FL012 WITH VSBYS 1-2SM ARE LIKELY 08Z TO 15Z.
THEN SCATTERED CLOUDS AND LIGHT NORTHWEST WINDS ARE FORECAST FOR
THE MAJORITY OF THE PERIOD AFTER 15Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM...MILLER
AVIATION...DERGAN
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
328 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT AUG 30 2014
REMNANT CONVECTIVE DEBRIS WILL CONTINUE TO SLIDE SOUTHEASTWARD
ACROSS SW NEB THROUGH SUNRISE WHILE STRATUS CONTINUES TO DROP
SOUTHWARD ACROSS ERN SD. RAP LOW LEVEL RH PROGS WOULD SUGGEST THE
STRATUS WILL SAG TO NEAR THE NIOBRARA VALLEY BY 12-15Z OR SO AND THE
HRRR HAS LOW CLOUDS EVEN FURTHER SOUTH. HAVE ADJUSTED SKY COVER FOR
THAT. PREVIOUS FCST HAD MENTION OF FOG ALSO IN THE NERN ZONES AS A
RESULT OF PREVIOUS 24 HR RAINFALL AND BELIEVE THAT THIS WOULD ALSO
BE ALONG THE FRINGE OF LOWER CLOUDS WHICH IS A TYPICAL EVOLUTION
ANYWAY. SO HAVE LEFT THE MENTION OF FOG AS IT WAS...MORE PATCHY TWD
THE SWRN PORTION OF THE AREA...ALL OF WHICH SHOULD BURN OFF BY MID
MORNING. ON THE LARGER SCALE...A TRANSITORY UPPER RIDGE WILL
PROGRESS ACROSS THE AREA TODAY AS THE NRN STREAM REMAINS
ACTIVE...WITH LARGE SCALE SUBSIDENCE IN CONTROL THROUGH THE DAY.
NEXT LONG WAVE TROUGH IS DEVELOPING ACROSS THE PAC NW WITH A LEAD PV
ANOMALY MOVING QUICKLY ACROSS THE NRN ROCKIES TODAY. A LEE SIDE SFC
TROUGH WILL DEVELOP FROM WRN SD INTO THE TX PANHANDLE BY LATE
AFTERNOON AND THE RESPONSE WILL BE AN INCREASE OF SRLY WINDS AND
DEVELOPING THERMAL RIDGE ACROSS THE HIGH PLAINS. ON THE ERN EDGE OF
THE THERMAL RIDGE /WHICH WILL BE RETREATING NWD THROUGH THE DAY/
HIGHER DEW POINTS WILL EXIST. THERE IS WEAK CONVERGENCE ASSOCIATED
WITH THIS FEATURE AS IT RETREATS DURING THE DAY...BUT DEEP LAYER
LIFT DOES NOT LOOK EVIDENT. MAX TEMPS SHOULD CREEP A FEW DEGREES
HIGHER TODAY AS A RESULT OF THE DEVELOPING THERMAL RIDGE...MOST
NOTABLY IN THE SOUTHWEST AND EASTERN PANHANDLE.
ATTENTION THEN TURNS TO LOWERING HEIGHTS ACROSS THE NRN PLAINS SAT
NIGHT AND SUNDAY. LEAD PV ANOMALY /WHICH IS BEST DEFINED INITIALLY
BY 30.00Z GFS/ WILL APPROACH THE PANHANDLE BY LATE SAT
AFTERNOON...THOUGH WEAKENING AS IT MOVES INTO THE RIDGE POSITION.
CONVERGENCE ALONG THE LEE TROUGH IS WEAK INITIALLY BUT WILL LIKELY
PROVIDE ENOUGH LIFT ALONG WITH THE HIGHER TERRAIN FURTHER WEST TO
DEVELOP AT LEAST ISOLATED TSRA WHICH WILL MOVE EWD SAT EVE...THOUGH
LOW LEVELS WILL BE FAIRLY DRY AS SUGGESTED BY WRN FCST SOUNDINGS.
HIGH PLAINS NOCTURNAL LLJ DEVELOPS THROUGH SAT EVE WHICH WILL ADVECT
MID LEVEL INSTABILITY INTO THE CENTRAL PORTION OF THE STATE AND
SHOULD MAINTAIN ENOUGH DEEP LAYER LIFT TO SUPPORT ISOLATED TSRA INTO
THE WRN PORTION OF THE FCST AREA LATE EVE AND EARLY MORNING. NAM/GEM
AND GFS SUPPORT THIS THOUGH HIRES CAMS ARE NOT SO EAGER TO DEVELOP
PRECIP. GRIDS WILL INCLUDE ISOLATED TSRA MENTION...PROGRESSING
ACROSS THE AREA THROUGH SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT AUG 30 2014
12Z SUNDAY AND BEYOND. ZONAL UPPER LEVEL FLOW TO PREVAIL ACROSS
MUCH OF THE CONTIGUOUS 48 TO START OFF THE EXTENDED FORECAST
PERIOD...BUT THE PATTERN DOES SHIFT SLIGHTLY SOUTHWESTERLY ACROSS
THE HIGH PLAINS ON SUNDAY WITH THE APPROACH OF AN UPPER
TROPOSPHERIC NORTHERN ROCKIES SHORTWAVE. THE APPROACH OF THE
SHORTWAVE WILL ALLOW AN AREA OF SFC LOW PRESSURE AND ATTENDANT
BAROCLINIC ZONE TO MOVE EAST ACROSS THE REGION THROUGH THE DAY ON
SUNDAY...POTENTIALLY SETTING THE STAGE FOR AN ACTIVE SEVERE
WEATHER PATTERN ACROSS OUR EAST BY LATE AFTERNOON. GUIDANCE
CONTINUES TO FAVOR EAST OF A KLBF TO KANW LINE WHERE THERMAL
ADVECTION IS SHOWN AND CONVERGENCE ALONG THE BAROCLINIC ZONE WILL
BE MAXIMIZED. THE GFS...NAM...AND EC ALL SHOW CONVECTION FIRING IN
THIS AREA...SO GIVEN THE GOOD AGREEMENT OF NOT ONLY THE FINER
DETAILS BUT ALSO THE LARGER SCALE PATTERN...FELT THAT CONFIDENCE
WAS ENOUGH TO INTRODUCE LIKELY/S INTO THE FORECAST ACROSS OUR FAR
EAST /EAST OF A MAYWOOD TO NAPER LINE/...WITH SOLID CHANCE POPS
/40-50%/ FOR LOCATIONS EAST OF THE KANW TO KLBF LINE SUNDAY
AFTERNOON. THE UPPER TROPOSPHERIC FLOW REMAINS FAIRLY
PROGRESSIVE...SO STORMS SHOULD BE LARGELY REMOVED OF THE FORECAST
AREA BY 06Z MONDAY. SFC TD/S ARE PROJECTED TO REBOUND BACK INTO
THE LOWER TO MID 60S ACROSS OUR EAST AND WHEN COMBINED WITH STEEP
LOWER TO MID LEVEL LAPSE RATES WHICH PROMOTE SB POTENTIAL ENERGY
IN EXCESS OF 2500 J/KG...ROBUST UPDRAFTS ARE ANTICIPATED. DEEP
LAYER SHEAR IS SHOWN TO BE QUITE FAVORABLE FOR SEVERE
WEATHER...WITH THE MODELS PEGGING UPWARDS OF 40-50KTS 0-6KM BULK
SHEAR...LARGE HAIL WILL BE POSSIBLE. THE UPDRAFTS SHOULD QUICKLY
CONGEAL ALONG THE BAROCLINIC ZONE INTO A QUASI-LINEAR CONVECTIVE
BAND WHICH WOULD PROMOTE DAMAGING THUNDERSTORM WIND INTO THE
EVENING.
INTO EARLY NEXT WEEK...THERE REMAINS SOME DISCREPANCIES ON THE
TIMING OF THE EXITING TROUGH...MOST NOTABLY...THE EC RETAINS A PIECE
OF ENERGY WEST OF THE FORECAST AREA...BUT BRINGS IT THROUGH MONDAY
NIGHT. THE EC GENERATES LIGHT QPF ACROSS MUCH OF THE FORECAST AREA
DURING THIS TIME PERIOD. THE GFS IN COMPARISON IS DRY AND LACKS
MUCH OF THE EVIDENCE SUPPORTING THIS ADDITIONAL TROPOSPHERIC
PERTURBATION. GIVEN THE UNCERTAINTY...WENT AHEAD AND SCALED BACK
POPS MONDAY EVENING INTO EARLY TUESDAY...BUT WILL KEEP A SLIGHT
MENTION GOING.
BEYOND EARLY TUESDAY...THE CR ALLBLEND PROCEDURE PROJECTED A DRY
FORECAST THROUGH THURSDAY OF NEXT WEEK...AND THERE ARE NO ARGUMENTS
HERE AS AN OVERALL LACK OF OMEGA WOULD BE ANTICIPATED AS THE STORM
TRACK SHIFTS NORTH AND LOW AMPLITUDE RIDGING ENCOMPASSES MUCH OF THE
CONUS. LATE IN THE EXTENDED THERE MAY BE ANOTHER SHORTWAVE
IMPACTING THE CENTRAL PLAINS...HOWEVER THE MODELS SEEM TO BE BACKING
OFF THIS SOLUTION A BIT...FOCUSING THE BEST POTENTIAL WELL NORTH OF
THE CWA. WILL KEEP THE PROCEDURE UNCHANGED FOR NOW.
NOT ANTICIPATING ANY VIOLENT TEMPERATURE CHANGES THROUGH THE
EXTENDED PERIODS...BUT WITH EACH FRONTAL PASSAGE...TEMPERATURES WILL
MODERATE SOME. THE WARMEST DAY APPEARS TO COME MID-WEEK...AS HIGHS
ON WEDNESDAY ARE FORECAST TO APPROACH THE UPPER 80S TO LOWER 90S FOR
MOST LOCATIONS. OTHERWISE HIGHS IN THE 70S TO LOW TO MID 80S SHOULD
PREVAIL FOR MOST DAYS. LOWS IN THE 50S AND 60S SEEM TO BE THE NORM
OVER THE NEXT 7 DAYS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1225 AM CDT SAT AUG 30 2014
THE STORMS THAT OCCURRED FROM VTN-LBF AND EAST LEFT A MOIST COOL
NEAR SURFACE LAYER. THE COOL MOIST AIR...CLEAR SKY AND LIGHT WIND
WILL PROBABLY RESULT IN AT LEAST A FEW PATCHES OF FG/BR. THE AREA
MOST LIKELY TO HAVE MORE WIDESPREAD FOG WOULD BE ONL-BBW WHERE
SHOWERS AND THUNDERSTORMS LEFT SIGNIFICANT RAIN AMOUNTS THIS PAST
EVENING. THE RAPID REFRESH SHORT RANGE MODELS POINT TO VISIBILITY
LESS THAN 3SM ALONG AND EAST OF A VTN-ANW-BUB LINE WITH LESS THAN
1SM POSSIBLE. HOWEVER...THE SIGNIFICANT RAIN WAS ACTUALLY EAST OF
THAT LINE AND THE SHORT RANGE MODELS MAY HAVE A SLIGHT DISLOCATION
OF THAT AS INPUT AND THAT WOULD SKEW THE OUTPUT. THE TIMING OF THE
FG/BR WILL BE 10-14Z. SINCE VTN DID NOT HAVE ANY RAIN THIS PAST
EVENING...WE WILL NOT INCLUDE BR (OR FG) IN ITS TERMINAL FORECAST
AT THIS TIME. THE INFLUENCE OF WETLANDS IN THE VICINITY OF LBF
WILL ENHANCE THE PROBABILITY OF PATCHY FOG DEVELOPING AND WE WILL
INCLUDE 2SM WITH BCFG AT LBF.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JWS
LONG TERM...JACOBS
AVIATION...SPRINGER/JWS
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
652 PM EDT SAT AUG 30 2014
.SYNOPSIS...
EXPECT AN INCREASING CHANCE OF SHOWERS AND A FEW THUNDERSTORMS
TONIGHT AND ESPECIALLY ON SUNDAY AS WEAK LOW PRESSURE CROSSES THE
REGION. AFTER A MAINLY DRY DAY ON MONDAY...SHOWERS AND
THUNDERSTORMS RETURN IN EARNEST BY TUESDAY AS A MORE DEFINITIVE
SURFACE FRONT MAKES ITS WAY INTO THE REGION. TEMPERATURES WILL
REMAIN WARM THROUGH TUESDAY...THEN COOL BACK TO LATE SUMMER
SEASONAL NORMALS BEHIND THE FRONT BY MID TO LATE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 643 PM EDT SATURDAY...EARLY UPDATE TO FCST THIS EVENING TO
INCREASE POPS ACRS THE SLV. CRNT RADAR SHOWS A CLUSTER OF SHOWERS
WITH EMBEDDED THUNDERSTORMS DEVELOPING OVER CENTRAL LAKE ONTARIO.
USING THE TIME OF ARRIVAL TOOL...PLACES THIS ACTIVITY ACRS EXTREME
SOUTHWEST ST LAWRENCE COUNTY AROUND 00Z AND INTO THE CENTRAL
PORTION OF THE COUNTY BY 01Z. LATEST 21Z HRRR MODELS SEEMS TO BE
HANDLING PRECIP THE BEST AND SHOWS THIS AREA QUICKLY TRACKING
NORTHEAST INTO THE SLV...BUT WEAKENING AS BEST INSTABILITY IS
LOCATED ACRS WESTERN NY. WL MENTION CHC POPS WITH THIS SECONDARY
WARM FRNT AND ASSOCIATED LLVL JET. THESE SHOWERS WL RESULT IN A
JUMP IN SFC DWPTS...ESPECIALLY ACRS THE SLV/NORTHERN NY
TONIGHT...WITH THIS BOUNDARY LIFTING INTO THE CPV AFT 06Z.
THINKING ADDITIONAL SHOWERS COULD DEVELOP AFT MIDNIGHT ACRS
NORTHERN NY AND MOVE INTO THE CPV TWD 09Z. THIS IS ALL COVERED IN
CRNT FCST WITH CHC POPS...INCREASING TO LIKELY TOWARD DAY BREAK.
INSTABILITY IS MARGINAL AND ELEVATED ASSOCIATED WITH LLVL JET...SO
ONLY SCHC FOR THUNDER OVERNIGHT INTO EARLY SUNDAY MORNING. TEMPS
WL HOLD IN THE U50S NEK TO U60S SLV/CPV...ASSOCIATED WITH
INCREASED DWPTS AND GUSTY SOUTHERLY WINDS. THE HUMIDITY WL CONT TO
INCREASE OVERNIGHT INTO SUNDAY...ESPECIALLY IN THE CPV. EXPECT IT
TO FEEL PRETTY HUMID BY MIDDAY SUNDAY...ACRS MOST OF THE REGION.
PREVIOUS DISCUSSION FOLLOWS...
SOUTHERLY FLOW WILL CONTINUE THIS EVENING/TONIGHT AS HIGH PRESSURE
DEPARTS OFFSHORE AND A DAMPENING SFC TO MID LEVEL TROUGH PUSHES
EAST FROM THE GREAT LAKES/OHIO VALLEY. SCATTERED SHOWERS AND/OR
ISOLATED STORMS WILL BE POSSIBLE LATER THIS EVENING AND
TONIGHT...ESPECIALLY ACROSS OUR NRN NY COUNTIES WHERE SLIGHT H5
HEIGHT FALLS...INCREASING MOISTURE RETURN AND SOME MID LEVEL
INSTABILITY WILL BE PRESENT. TEMPERATURES TO HOLD ON THE MILD SIDE
(60S) AS CLOUDS SLOWLY INCREASE THROUGH TIME...ESPECIALLY IN THE
ST LAWRENCE AND CHAMPLAIN VALLEYS WHERE NOCTURNAL SOUTHERLY LLJ
DEVELOPMENT IS EXPECTED NEAR THE 925 MB LEVEL.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 330 PM EDT SATURDAY...MOST INCLEMENT WEATHER IN THE SHORT
TERM THEN OCCURS ON SUNDAY INTO SUNDAY EVENING AS AFOREMENTIONED
TROUGH SWINGS THROUGH THE AREA ALONG WITH NUMEROUS SHOWERS/STORMS.
NEGLIGIBLE BAROCLINICITY ACROSS THE BOUNDARY COMBINED WITH PLENTY
OF CLOUDS AND LIMITED INSTABILITY SHOULD KEEP ANY ENHANCED SVR
THREAT AT A MINIMUM...BUT WE COULD SEE A FEW STRONGER CELLS ACROSS
OUR FAR SRN VT COUNTIES WHERE SOME MORNING SUN WILL BE POSSIBLE.
GUSTY WINDS WOULD BE THE PRIMARY THREAT IF ANYTHING WOULD DEVELOP.
OTHERWISE EXPECT A GENERALLY CLOUDY AND OCCASIONALLY WET DAY AS
SHOWERS/SCT GARDEN-VARIETY STORMS TRAVERSE THE REGION. NARROW PWAT
AXIS OF 1.7-1.9 INCHES WILL EXIST ALONG AND JUST AHEAD OF THE
BOUNDARY SO SOME BRIEF HEAVIER DOWNPOURS ARE CERTAINLY POSSIBLE.
HOWEVER MEAN STORM MOVEMENT OF 15 TO 20 MPH SHOULD LIMIT ANY
HYDROLOGICAL CONCERNS. HIGHS MAINLY IN THE 70S GIVEN THE AMPLE
CLOUDS.
EVENING SHOWERS/STORMS THEN EXIT EAST THROUGH THE EVENING HOURS ON
SUNDAY AS TROUGH CLEARS THE AREA LEAVING VARIABLY CLOUDY SKIES
OVERNIGHT. COULD SEE SOME PATCHY FOG HERE AND THERE BUT LOW LEVEL
WIND FIELDS HIGH ENOUGH THAT IT SHOULD BE MORE CONFINED TO MOST
FAVORED CLIMATOLOGICAL AREAS. AS MENTIONED ABOVE...LITTLE AIRMASS
CHANGE BEHIND THE BOUNDARY...SO LOWS GENERALLY IN THE 60S
EXPECTED...PERHAPS A FEW UPPER 50S IN COOLER NRN MTN LOCALES.
BY MONDAY WEAK SHORTWAVE RIDGING DEVELOPS BETWEEN DEPARTING TROUGH
AND A MORE SUBSTANTIAL UPPER TROUGH DIGGING ACROSS THE GREAT LAKES
STATES TO OUR WEST. CAN`T COMPLETELY RULE OUT AN ISOLATED
SHOWER/STORM JUST ABOUT ANYWHERE WITH SOME LINGERING MOISTURE AND
PBL INSTABILITY OF 200-600 J/KG...BUT MOST LOCALES SHOULD REMAIN
LARGELY DRY WITH LACK OF LARGE-SCALE FORCING. BLENDED 18Z 925MB
THERMAL PROFILES SUGGEST HIGHS FROM 77 TO 83 OR SO UNDER PARTIAL
SUNSHINE...WARMEST IN THE BROADER VALLEYS.
THEN PARTLY CLOUDY AND CONTINUED MAINLY DRY MONDAY NIGHT AS
SOUTHERLY FLOW SLOWLY INCREASES ONCE AGAIN AHEAD OF APPROACHING
UPPER TROUGH AND ATTENDANT SFC BOUNDARY TO OUR WEST. WILL CONTINUE
PRIOR IDEA OF LOWER CHANCES FOR SHOWERS/STORMS ACROSS OUR
WESTERNMOST NY COUNTIES OVERNIGHT IN CLOSER PROXIMITY TO THE
BOUNDARY AND BETTER DYNAMICAL FORCING. MAINLY DRY FURTHER EAST INTO
VERMONT HOWEVER. TEMPERATURES REMAIN ON THE MILD SIDE...GENERALLY IN
THE 60S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 341 PM EDT SATURDAY...THIS LONG TERM PERIOD LOOKS VERY CONSISTENT
TO PREVIOUS FCST.
THE MAIN WEATHER CONCERN DURING THIS LONG TERM PERIOD WILL BE TUESDAY
AND TUESDAY NIGHT. UPPER LEVEL TROUGH AND ITS ASSOCIATED COLD
FRONT WILL BE MOVING INTO THE AREA DURING THE AFTERNOON AND
EVENING HOURS. AHEAD OF THE FRONT...ABOVE NORMAL TEMPERATURES ARE
EXPECTED WITH HIGHS IN THE 80S AND COMBINED WITH INCREASING DEW
POINTS...SUFFICIENT INSTABILITY WILL DEVELOP OVER THE AREA AHEAD
OF THE FRONT. DEEP LAYER SHEAR WILL ALSO BE INCREASING OVER THIS
AREA OF DEVELOPING INSTABILITY. ALL OF THIS SUGGESTS THE POTENTIAL
FOR THUNDERSTORMS...SOME OF WHICH COULD BE STRONG OR SEVERE. THUS
WILL HAVE TO KEEP AN EYE ON THIS SYSTEM.
THEREAFTER...FRONT EXITS THE AREA BY EARLY WED MRNG AND UPPER LEVEL
FLOW FOR THE REMAINDER OF THE WEEK QUICKLY RETURNS TO ZONAL FLOW ON
NORTHERN PERIPERHY OF SOUTHEAST CONUS RIDGE. THEREFORE...PRETTY MUCH
DRIER AIR BUT AOA SEASONABLE TEMPS CONTINUE BEFORE ANOTHER NRN
STREAM SHORTWAVE...THIS ONE FURTHER NORTH...MOVES ACROSS QUEBEC
WITH A SURFACE FRONT IN THE FRI NGT-SAT TIMEFRAME. HIGH TEMPS IN THE
M-U70S TO L80S.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
THROUGH 18Z SUNDAY...OVERALL LOOKING AT VFR CONDITIONS THROUGH
MOST OFTHE PERIOD. MAINLY MID AND HIGH LEVEL CLOUDS THROUGH THE
EVENING...THEN CEILINGS BEGIN TO LOWER TONIGHT WITH BROKEN TO
OVERCAST CEILINGS AROUND 5000 FEET ARD/AFT 06Z SUNDAY SPREADING EAST.
THERE WILL ALSO BE SOME LIGHT SHOWERS MOVING FROM WEST TO EAST
BETWEEN 06Z AND 12Z...BUT VISIBILITIES WILL REMAIN UNRESTRICTED.
SHOWERS BECOME MORE NUMEROUS AND LOCALLY HEAVY DUE TO HIGH
PRECIPITABLE WATERS THUS ANY SHOWERS MAY HAVE BRIEF MVFR-IFR IN
VSBY DUE TO RAINFALL INTENSITY WITH MVFR CIGS LIKELY FOR MOST ON SUNDAY.
WINDS WILL BE LIGHTER THAN TODAY...SSW 10 KTS OR SO.
OUTLOOK 18Z SUNDAY THROUGH WEDNESDAY...
18Z SUNDAY ONWARD...MAINLY VFR, THOUGH MVFR/BRIEF IFR IN
SCATTERED SHOWERS AND THUNDERSTORMS THAT WILL BE MOST NUMEROUS
SUNDAY AND PERHAPS AGAIN LATE TUESDAY.
&&
.MARINE...
AS OF 300 PM EDT SATURDAY...SOUTH WINDS OF 15 TO 25 KNOTS WILL
CONTINUE THROUGH THE REMAINDER OF TODAY...TONIGHT...AND INTO
SUNDAY MORNING. GUSTS WILL REACH 30 KNOTS AT TIMES. THUS A LAKE
WIND ADVISORY REMAINS IN EFFECT. THESE WINDS WILL CREATE WAVES OF
2 TO 4 FEET...WITH THE HIGHEST WAVES IN THE OPEN WATERS OF THE
CENTRAL AND NORTHERN PORTIONS OF THE LAKE. BY SUNDAY
AFTERNOON...SOUTH WINDS WILL TAPER OFF TO 10 TO 20 KNOTS AND WAVES
WILL SUBSIDE TO 1 TO 3 FEET. WIDESPREAD SHOWERS AND THUNDERSTORMS
WILL ALSO DEVELOP ON SUNDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG/TABER
SHORT TERM...JMG
LONG TERM...EVENSON/SLW
AVIATION...EVENSON/SLW
MARINE...WFO BTV
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1025 PM EDT SUN AUG 31 2014
.SYNOPSIS...
STRENGTHENING BERMUDA HIGH PRESSURE WILL BRING SUMMERTIME HEAT AND
HUMIDITY WITH A RISK FOR SHOWERS AND THUNDERSTORMS EACH DAY. THE
MOST UNCOMFORTABLE CONDITIONS ARE EXPECTED EARLY IN THE WEEK. A
DECAYING FRONT MAY SNEAK INTO THE AREA THURSDAY AND FRIDAY...PERHAPS
INCREASING THE COVERAGE OF SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 1000 PM SUNDAY...THE WEAKENING CONVECTION MOVED INTO PORTIONS
OF DARLINGTON AND FLORENCE COUNTIES AND THEN DISSIPATED. ANOTHER
SMALL AREA OF WARMING CLOUD TOPS WAS PRODUCING SHOWERS TO THE WEST
OF FLORENCE AND WILLIAMSBURG COUNTIES LATE THIS EVE. THIS ACTIVITY
IS NO LONGER PUSHING EASTWARD AND IS EXPECTED TO DISSIPATE UPSTREAM
OF OUR FORECAST AREA. OUTFLOW BOUNDARIES FROM THIS CONVECTION SHOULD
BECOME ACTIVE ON MONDAY.
THE THICKER CLOUD CANOPY ACROSS MAINLY THE I-95 CORRIDOR IN SOUTH
CAROLINA CONTINUES TO WARM AND THIN LATE THIS EVE. MAINLY THIN
HIGHER CLOUDS ARE EXPECTED THROUGH MUCH OF THE NIGHT. AS WE PROGRESS
THROUGH THE OVERNIGHT...SHOULD START TO SEE SOME STRATOCUMULUS IN
ASSOCIATION WITH OFFSHORE CONVECTION AT LEAST SKIRT THE COAST. MORE
INLAND AREAS MAY SEE SCT TO PERHAPS BKN STRATUS LATE.
SHOWERS DEVELOPING ACROSS THE BAROCLINIC FAVORED WARM WATERS OF THE
ATLANTIC MAY SKIRT THE COAST TOWARD MORNING. THE FLOW HAS BACKED A
LITTLE TO THE SW AS THE BERMUDA RIDGE FURTHER STRENGTHENS ACROSS THE
AREA. THIS WILL HAVE A TENDENCY TO KEEP THE SHOWERS OFFSHORE THROUGH
SUNRISE...PERHAPS CLIPPING THE SOUTHPORT TO CAROLINA BEACH AREA
AROUND DAYBREAK.
A SLIGHTLY STRONGER NOCTURNAL JET SHOULD LARGELY PRECLUDE ANY
SIGNIFICANT FOG DEVELOPMENT AND WILL NOT INCLUDE MENTION AT THIS
TIME. THIS SAME JETTING SHOULD BE ENOUGH TO KEEP THE BOUNDARY LAYER
FROM REMAINING FULLY DECOUPLED THROUGH THE NIGHT. THUS...WITH AT
LEAST A SLIGHT SOUTHERLY BREEZE FROM TIME TO TIME...WOULD EXPECT
MINIMUMS MAINLY IN THE LOWER TO MID 70S. AT THE BEACHES...WHERE THE
BREEZE MAY PERSIST MUCH OF THE NIGHT...WILL FORECAST LOWS AROUND 80.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...THE NORTHERN 2/3RDS OF THE CONTERMINOUS U.S.
WILL HAVE FAST WESTERLY FLOW...WHEREAS THE SOUTHERN 1/3RD WILL
HAVE A FLATTENED RIDGE ALOFT. THIS FLOW WILL KEEP DYNAMICS
ASSOCIATED WITH ANY S/W TROFS WITHIN THIS WESTERLY FLOW
ALOFT...NORTH OF THE FA. AT THE SFC...RIDGING FROM THE WESTERN
ATLANTIC HIGH WILL BE THE PRIMARY WEATHER FEATURE TO AFFECT THE
FA. THE DIURNALLY DRIVEN SEA BREEZE AND THE PIEDMONT TROF...WILL
PROVIDE THE PRIMARY SOURCES FOR LIFT EACH DAY FOR CONVECTION TO
OCCUR. AT THIS POINT HAVE STAYED WITH CLIMO CHANCES FOR CONVECTION
WHICH IS BASICALLY AROUND 30 PERCENT. ANY WEAK VORTS OR S/W TROFS
ALOFT ABLE TO WORK THEIR WAY SOUTHWARD THAN WHAT MODELS INDICATE
COULD RESULT WITH AN INCREASE IN POPS ABOVE CLIMO...30 PERCENT
CHANCE. AVAILABLE MOISTURE WILL NO LONGER BE IN QUESTION AS
MOISTURE IS PROGGED TO INCREASE THRU THE ATM COLUMN FROM MONDAY
NIGHT THROUGH THE REMAINDER OF THE SHORT TERM VIA LATEST MODEL
TIME HEIGHT DISPLAYS AND MODEL SOUNDING DATA. OF THE 2
DAYS...TUE WILL BE ILLUSTRATED WITH THE HIER POPS CHANCE AND CLOUD
OVERALL COVERAGE. FOR TEMPS...PREVIOUS FORECAST WAS USED WITH ONLY
MINOR TWEAKING NEEDED BASED ON 12Z MODEL MOS DATA.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL DOMINATE AT THE SURFACE
WITH A WEAKENED GRADIENT FLOW. OVERALL A WARM AND HUMID AIRMASS WILL
REMAIN IN PLACE WITH LOCALIZED SHOWER ACTIVITY EACH DAY MAINLY
ASSOCIATED WITH SEA BREEZE BOUNDARY AND PIEDMONT TROUGH INLAND. PCP
WATER VALUES REMAIN UP AROUND 2 INCHES BUT MOISTURE PROFILES SHOW
MOST OF THE MOISTURE LOCKED IN ABOVE H5 WITH MORE IN THE WAY OF
UPPER LEVEL CLOUDS. THE PREVAILING FLOW WILL REMAIN LIGHT WITH SEA
BREEZE KICKING UP EACH AFTERNOON.
FLAT MID TO UPPER RIDGE AMPLIFIES SLIGHTLY UP THROUGH THE SOUTHEAST
WEDNESDAY THROUGH FRIDAY BEFORE A DEEPER SHORTWAVE RIDES ACROSS THE
GREAT LAKES AND DIGS SOUTHWARD PUSHING A COLD FRONT INTO THE
CAROLINAS BY THE LATTER HALF OF NEXT WEEKEND. THIS WILL PROVIDE
LIMITED UPPER LEVEL SUPPORT FOR CONVECTION THROUGH THE WEEK INTO THE
FIRST HALF OF THE WEEKEND.
NOT EXPECTING ANY CHANGE IN AIR MASS THROUGH THE PERIOD WITH MAX
TEMPS UP AROUND 90 OR SO AND OVERNIGHT LOWS HOLDING UP AROUND 70 OR
SO. BUILDING H5 HEIGHTS THROUGH FRI SHOULD HELP KEEP TEMPS ABOVE
NORMAL AND WILL BEGIN A SLIGHT DOWNWARD TREND AS TROUGH MAKES ITS
WAY EAST INTO NEXT WEEKEND.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...CURRENT RADAR IMAGERY SHOWS A LINE OF SCT CONVECTION TO
OUR WEST ASSOCIATED WITH THE PIEDMONT TROUGH. THE HRRR SUGGESTS THIS
ACTIVITY WILL CONTINUE TO WEAKEN THIS EVENING. DO NOT ANTICIPATE ANY
IMPACTS TO KFLO/KLBT ATTM...OTHER THAN PERHAPS SOME INCREASED MID
LEVEL DEBRIS CLOUDS TONIGHT.
VERY SIMILAR PATTERN AS THE PAST COUPLE NIGHTS WITH BERMUDA HIGH
PRESSURE STILL STATIONED WELL OFFSHORE. EXPECT WINDS TO BECOME LIGHT
S-SW AOB 5 KT OVERNIGHT. SOME SCT 1-3KFT CLOUDS MAY SKIRT THE
COASTAL TERMS AGAIN EARLY MON WITH NOCTURNAL SHOWERS OFFSHORE...BUT
DO NOT EXPECT PERSISTENT MVFR CIGS TO DEVELOP. BEST CHANCE FOR IFR
OR LOWER CIGS/VSBYS WILL BE INLAND AT KFLO/KLBT...MOST LIKELY
BETWEEN 09-12Z. WILL INCLUDE TEMPO IFR VSBYS/LIFR CIGS FOR THESE
SITES AROUND DAYBREAK. VFR WILL PREVAIL DURING THE DAY MON WITH
SOUTHWEST WINDS AROUND 5 KT...BECOMING SOUTH AROUND 10 KT AT THE
COASTAL SITES FOLLOWING MIDDAY SEA BREEZE PASSAGE. SLIGHT CHANCE OF
AFTN SHOWERS/TSTMS DOES NOT WARRANT A TAF MENTION ATTM.
EXTENDED OUTLOOK...CHANCE OF ISOLATED TO SCATTERED AFTN SHOWERS AND
TSTMS THROUGH FRIDAY. PATCHES OF MVFR/IFR FOG OR STRATUS MAY ALSO
DEVELOP EACH MORNING. BUT OVERALL VFR CONDITIONS SHOULD PREVAIL.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 PM SUNDAY...A SLIGHTLY STRONGER NOCTURNAL JET AND A
STRENGTHENING BERMUDA RIDGE WILL KEEP SOUTHWEST WINDS ACROSS THE
WATERS TONIGHT. WIND SPEEDS WILL BE ON THE ORDER OF 10 TO 15 KT WITH
GUSTS AROUND 20 KT. SEAS WILL BE 2 TO 3 FT WITH SOME 4 FT SEAS
EXPECTED ACROSS THE OUTERMOST WATERS. DEVELOPING OFFSHORE CONVECTION
MAY MOVE WITHIN 20 NM LATE...ESPECIALLY OFF THE CAPE FEAR COAST.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...THE PRESSURE PATTERN ACROSS THE AREA WATERS
WILL BE THE RESULT OF THE INTERACTION BETWEEN RIDGING FROM THE
WESTERN ATLANTIC HIGH AND PIEDMONT TROUGH. LOOKING AT SYNOPTIC WINDS
IN THE SSW THRU WSW WIND DIRECTION...WITH AN OVERALL SLIGHT BACKING
EACH AFTN AND EVENING FROM THE DIURNALLY DRIVEN SEA BREEZE. THE SFC
PG WILL BECOME MODEST AT BEST RESULTING WITH 10-15 KT OR A SOLID 15
KT WIND SPEED. SIGNIFICANT SEAS WILL RUN 2 TO OCCASIONALLY 3
FT...WITH MAJORITY OF THE SIG. SEAS A RESULT OF THE 2 FOOT SE GROUND
SWELL RUNNING ROUGHLY AT 9-10 SECOND PERIODS. WIND DRIVEN WAVES
ESPECIALLY FROM THE SEA BREEZE WILL RUN SIG. SEAS UP TO 3 TO
POSSIBLY 4 FT.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL CONTINUE TO DOMINATE
WITH A RELAXED GRADIENT FLOW. OVERALL EXPECT WEAK SOUTHERLY FLOW
10 KTS OR LESS DOMINATED BY SEA/LAND BREEZE. WINDS WILL SPIKE UP
EACH AFTERNOON NEAR SHORE AS SEA BREEZE STRENGTHENS. SEAS WILL
REMAIN FAIRLY BENIGN WITH HEIGHTS LESS THAN 3 FT AND SLIGHT CHOP
IN THE AFTN SEA BREEZE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
750 PM EDT SUN AUG 31 2014
.SYNOPSIS...
STRENGTHENING BERMUDA HIGH PRESSURE WILL BRING SUMMERTIME HEAT AND
HUMIDITY WITH A RISK FOR SHOWERS AND THUNDERSTORMS EACH DAY. THE
MOST UNCOMFORTABLE CONDITIONS ARE EXPECTED EARLY IN THE WEEK. A
DECAYING FRONT MAY SNEAK INTO THE AREA THURSDAY AND FRIDAY...PERHAPS
INCREASING THE COVERAGE OF SHOWERS AND THUNDERSTORMS.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 700 PM SUNDAY...SHOWERS AND THUNDERSTORMS ALONG THE PIEDMONT
TROUGH WILL SLOWLY DISSIPATE AS THEY REACH THE WESTERNMOST
COMMUNITIES IN OUR FORECAST AREA. A SHOWER OR THUNDERSTORM MAY OCCUR
IN THE HARTSVILLE TO TIMMONSVILLE AREA PRIOR TO 9 PM. THE LEADING
EDGE OF THE THICK CANOPY OF CLOUDS WILL REACH AS FAR EAST AS
LUMBERTON TO MARION TO CADES BEFORE BEGINNING TO SLOWLY ERODE AFTER
10 PM.
A FEW LATE NIGHT SHOWERS DEVELOPING ACROSS THE BAROCLINIC FAVORED
WARM WATERS OF THE ATLANTIC MAY SKIRT THE COAST TOWARD MORNING. THE
FLOW HAS BACKED A LITTLE TO THE SW AS THE BERMUDA RIDGE FURTHER
STRENGTHENS ACROSS THE AREA. THIS WILL HAVE A TENDENCY TO KEEP THE
SHOWERS OFFSHORE THROUGH SUNRISE...PERHAPS CLIPPING THE SOUTHPORT TO
CAROLINA BEACH AREA AROUND DAYBREAK.
A SLIGHTLY STRONGER NOCTURNAL JET SHOULD LARGELY PRECLUDE ANY
SIGNIFICANT FOG DEVELOPMENT AND WILL NOT INCLUDE MENTION AT THIS
TIME. THIS SAME JETTING SHOULD BE ENOUGH TO KEEP THE BOUNDARY LAYER
FROM REMAINING FULLY DECOUPLED THROUGH THE NIGHT. THUS...WITH AT
LEAST A SLIGHT SOUTHERLY BREEZE FROM TIME TO TIME...WOULD EXPECT
MINIMUMS MAINLY IN THE LOWER TO MID 70S. AT THE BEACHES...WHERE THE
BREEZE MAY PERSIST MUCH OF THE NIGHT...WILL FORECAST LOWS AROUND 80.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...THE NORTHERN 2/3RDS OF THE CONTERMINOUS U.S.
WILL HAVE FAST WESTERLY FLOW...WHEREAS THE SOUTHERN 1/3RD WILL
HAVE A FLATTENED RIDGE ALOFT. THIS FLOW WILL KEEP DYNAMICS
ASSOCIATED WITH ANY S/W TROFS WITHIN THIS WESTERLY FLOW
ALOFT...NORTH OF THE FA. AT THE SFC...RIDGING FROM THE WESTERN
ATLANTIC HIGH WILL BE THE PRIMARY WEATHER FEATURE TO AFFECT THE
FA. THE DIURNALLY DRIVEN SEA BREEZE AND THE PIEDMONT TROF...WILL
PROVIDE THE PRIMARY SOURCES FOR LIFT EACH DAY FOR CONVECTION TO
OCCUR. AT THIS POINT HAVE STAYED WITH CLIMO CHANCES FOR CONVECTION
WHICH IS BASICALLY AROUND 30 PERCENT. ANY WEAK VORTS OR S/W TROFS
ALOFT ABLE TO WORK THEIR WAY SOUTHWARD THAN WHAT MODELS INDICATE
COULD RESULT WITH AN INCREASE IN POPS ABOVE CLIMO...30 PERCENT
CHANCE. AVAILABLE MOISTURE WILL NO LONGER BE IN QUESTION AS
MOISTURE IS PROGGED TO INCREASE THRU THE ATM COLUMN FROM MONDAY
NIGHT THROUGH THE REMAINDER OF THE SHORT TERM VIA LATEST MODEL
TIME HEIGHT DISPLAYS AND MODEL SOUNDING DATA. OF THE 2
DAYS...TUE WILL BE ILLUSTRATED WITH THE HIER POPS CHANCE AND CLOUD
OVERALL COVERAGE. FOR TEMPS...PREVIOUS FORECAST WAS USED WITH ONLY
MINOR TWEAKING NEEDED BASED ON 12Z MODEL MOS DATA.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL DOMINATE AT THE SURFACE
WITH A WEAKENED GRADIENT FLOW. OVERALL A WARM AND HUMID AIRMASS WILL
REMAIN IN PLACE WITH LOCALIZED SHOWER ACTIVITY EACH DAY MAINLY
ASSOCIATED WITH SEA BREEZE BOUNDARY AND PIEDMONT TROUGH INLAND. PCP
WATER VALUES REMAIN UP AROUND 2 INCHES BUT MOISTURE PROFILES SHOW
MOST OF THE MOISTURE LOCKED IN ABOVE H5 WITH MORE IN THE WAY OF
UPPER LEVEL CLOUDS. THE PREVAILING FLOW WILL REMAIN LIGHT WITH SEA
BREEZE KICKING UP EACH AFTERNOON.
FLAT MID TO UPPER RIDGE AMPLIFIES SLIGHTLY UP THROUGH THE SOUTHEAST
WEDNESDAY THROUGH FRIDAY BEFORE A DEEPER SHORTWAVE RIDES ACROSS THE
GREAT LAKES AND DIGS SOUTHWARD PUSHING A COLD FRONT INTO THE
CAROLINAS BY THE LATTER HALF OF NEXT WEEKEND. THIS WILL PROVIDE
LIMITED UPPER LEVEL SUPPORT FOR CONVECTION THROUGH THE WEEK INTO THE
FIRST HALF OF THE WEEKEND.
NOT EXPECTING ANY CHANGE IN AIR MASS THROUGH THE PERIOD WITH MAX
TEMPS UP AROUND 90 OR SO AND OVERNIGHT LOWS HOLDING UP AROUND 70 OR
SO. BUILDING H5 HEIGHTS THROUGH FRI SHOULD HELP KEEP TEMPS ABOVE
NORMAL AND WILL BEGIN A SLIGHT DOWNWARD TREND AS TROUGH MAKES ITS
WAY EAST INTO NEXT WEEKEND.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...CURRENT RADAR IMAGERY SHOWS A LINE OF SCT CONVECTION TO
OUR WEST ASSOCIATED WITH THE PIEDMONT TROUGH. THE HRRR SUGGESTS THIS
ACTIVITY WILL CONTINUE TO WEAKEN THIS EVENING. DO NOT ANTICIPATE ANY
IMPACTS TO KFLO/KLBT ATTM...OTHER THAN PERHAPS SOME INCREASED MID
LEVEL DEBRIS CLOUDS TONIGHT.
VERY SIMILAR PATTERN AS THE PAST COUPLE NIGHTS WITH BERMUDA HIGH
PRESSURE STILL STATIONED WELL OFFSHORE. EXPECT WINDS TO BECOME LIGHT
S-SW AOB 5 KT OVERNIGHT. SOME SCT 1-3KFT CLOUDS MAY SKIRT THE
COASTAL TERMS AGAIN EARLY MON WITH NOCTURNAL SHOWERS OFFSHORE...BUT
DO NOT EXPECT PERSISTENT MVFR CIGS TO DEVELOP. BEST CHANCE FOR IFR
OR LOWER CIGS/VSBYS WILL BE INLAND AT KFLO/KLBT...MOST LIKELY
BETWEEN 09-12Z. WILL INCLUDE TEMPO IFR VSBYS/LIFR CIGS FOR THESE
SITES AROUND DAYBREAK. VFR WILL PREVAIL DURING THE DAY MON WITH
SOUTHWEST WINDS AROUND 5 KT...BECOMING SOUTH AROUND 10 KT AT THE
COASTAL SITES FOLLOWING MIDDAY SEA BREEZE PASSAGE. SLIGHT CHANCE OF
AFTN SHOWERS/TSTMS DOES NOT WARRANT A TAF MENTION ATTM.
EXTENDED OUTLOOK...CHANCE OF ISOLATED TO SCATTERED AFTN SHOWERS AND
TSTMS THROUGH FRIDAY. PATCHES OF MVFR/IFR FOG OR STRATUS MAY ALSO
DEVELOP EACH MORNING. BUT OVERALL VFR CONDITIONS SHOULD PREVAIL.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 700 PM SUNDAY...A SLIGHTLY STRONGER NOCTURNAL JET AND A
STRENGTHENING BERMUDA RIDGE WILL KEEP SOUTHWEST WINDS ACROSS THE
WATERS TONIGHT. WIND SPEEDS WILL BE ON THE ORDER OF 10 TO 15 KT WITH
GUSTS AROUND 20 KT. SEAS WILL BE 2 TO 3 FT WITH SOME 4 FT SEAS
EXPECTED ACROSS THE OUTERMOST WATERS.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...THE PRESSURE PATTERN ACROSS THE AREA WATERS
WILL BE THE RESULT OF THE INTERACTION BETWEEN RIDGING FROM THE
WESTERN ATLANTIC HIGH AND PIEDMONT TROUGH. LOOKING AT SYNOPTIC WINDS
IN THE SSW THRU WSW WIND DIRECTION...WITH AN OVERALL SLIGHT BACKING
EACH AFTN AND EVENING FROM THE DIURNALLY DRIVEN SEA BREEZE. THE SFC
PG WILL BECOME MODEST AT BEST RESULTING WITH 10-15 KT OR A SOLID 15
KT WIND SPEED. SIGNIFICANT SEAS WILL RUN 2 TO OCCASIONALLY 3
FT...WITH MAJORITY OF THE SIG. SEAS A RESULT OF THE 2 FOOT SE GROUND
SWELL RUNNING ROUGHLY AT 9-10 SECOND PERIODS. WIND DRIVEN WAVES
ESPECIALLY FROM THE SEA BREEZE WILL RUN SIG. SEAS UP TO 3 TO
POSSIBLY 4 FT.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL CONTINUE TO DOMINATE
WITH A RELAXED GRADIENT FLOW. OVERALL EXPECT WEAK SOUTHERLY FLOW
10 KTS OR LESS DOMINATED BY SEA/LAND BREEZE. WINDS WILL SPIKE UP
EACH AFTERNOON NEAR SHORE AS SEA BREEZE STRENGTHENS. SEAS WILL
REMAIN FAIRLY BENIGN WITH HEIGHTS LESS THAN 3 FT AND SLIGHT CHOP
IN THE AFTN SEA BREEZE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
723 PM EDT SUN AUG 31 2014
.SYNOPSIS...
STRENGTHENING BERMUDA HIGH PRESSURE OFFSHORE WILL BRING
SUMMERTIME HEAT AND HUMIDITY THROUGH THE LABOR DAY WEEKEND WITH A
FEW SHOWERS AND THUNDERSTORMS POSSIBLE. A WEAK COLD FRONT WILL
APPROACH FROM THE NORTH LATE THIS WEEK...BUT WILL LIKELY STALL BEFORE
REACHING THE AREA. BERMUDA HIGH PRESSURE AND A PIEDMONT TROUGH
WILL REMAIN THE DOMINANT FEATURES INTO NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 300 PM SUNDAY...TYPICAL SUMMERTIME WEATHER PATTERN
CONTINUES WITH HIGH PRESSURE OVER THE WESTERN ATLANTIC KEEPING UP
A STEADY WARM AND MOIST SOUTHERLY FLOW THROUGH THE NEAR TERM. MID
AND UPPER LEVELS REMAIN QUITE DRY AND MODEL SOUNDINGS SUGGEST THAT
THEY WILL CONTINUE TO BE SO THROUGH THE OVERNIGHT HOURS. DUE TO
THIS...ISOLATED SHOWER ACTIVITY FROM EARLIER TODAY HAS FADED AS
THE DRYER AIR ALOFT MIXED DOWN TO THE SURFACE. LATEST VISIBLE
SATELLITE LOOPS SHOW THE EXTENSIVE CU FIELD THAT DEVELOPED OVER
THE FORECAST AREA THIS MORNING HAS ALSO BEGUN TO ERODE AS THE
MIXING PROGRESSES. EXPECT THE REMAINDER OF THE AFTERNOON HOURS AND
OVERNIGHT TO BE DRY.
CONTINUED WARM SOUTHERLY FLOW WILL KEEP OVERNIGHT TEMPERATURES A TAD
ABOVE NORMAL...WITH LOWS IN THE LOWER TO MID 70S MOST PLACES.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...THE NORTHERN 2/3RDS OF THE CONTERMINOUS U.S.
WILL HAVE FAST WESTERLY FLOW...WHEREAS THE SOUTHERN 1/3RD WILL
HAVE A FLATTENED RIDGE ALOFT. THIS FLOW WILL KEEP DYNAMICS
ASSOCIATED WITH ANY S/W TROFS WITHIN THIS WESTERLY FLOW
ALOFT...NORTH OF THE FA. AT THE SFC...RIDGING FROM THE WESTERN
ATLANTIC HIGH WILL BE THE PRIMARY WEATHER FEATURE TO AFFECT THE
FA. THE DIURNALLY DRIVEN SEA BREEZE AND THE PIEDMONT TROF...WILL
PROVIDE THE PRIMARY SOURCES FOR LIFT EACH DAY FOR CONVECTION TO
OCCUR. AT THIS POINT HAVE STAYED WITH CLIMO CHANCES FOR CONVECTION
WHICH IS BASICALLY AROUND 30 PERCENT. ANY WEAK VORTS OR S/W TROFS
ALOFT ABLE TO WORK THEIR WAY SOUTHWARD THAN WHAT MODELS INDICATE
COULD RESULT WITH AN INCREASE IN POPS ABOVE CLIMO...30 PERCENT
CHANCE. AVAILABLE MOISTURE WILL NO LONGER BE IN QUESTION AS
MOISTURE IS PROGGED TO INCREASE THRU THE ATM COLUMN FROM MONDAY
NIGHT THROUGH THE REMAINDER OF THE SHORT TERM VIA LATEST MODEL
TIME HEIGHT DISPLAYS AND MODEL SOUNDING DATA. OF THE 2
DAYS...TUE WILL BE ILLUSTRATED WITH THE HIER POPS CHANCE AND CLOUD
OVERALL COVERAGE. FOR TEMPS...PREVIOUS FORECAST WAS USED WITH ONLY
MINOR TWEAKING NEEDED BASED ON 12Z MODEL MOS DATA.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL DOMINATE AT THE SURFACE
WITH A WEAKENED GRADIENT FLOW. OVERALL A WARM AND HUMID AIRMASS WILL
REMAIN IN PLACE WITH LOCALIZED SHOWER ACTIVITY EACH DAY MAINLY
ASSOCIATED WITH SEA BREEZE BOUNDARY AND PIEDMONT TROUGH INLAND. PCP
WATER VALUES REMAIN UP AROUND 2 INCHES BUT MOISTURE PROFILES SHOW
MOST OF THE MOISTURE LOCKED IN ABOVE H5 WITH MORE IN THE WAY OF
UPPER LEVEL CLOUDS. THE PREVAILING FLOW WILL REMAIN LIGHT WITH SEA
BREEZE KICKING UP EACH AFTERNOON.
FLAT MID TO UPPER RIDGE AMPLIFIES SLIGHTLY UP THROUGH THE SOUTHEAST
WEDNESDAY THROUGH FRIDAY BEFORE A DEEPER SHORTWAVE RIDES ACROSS THE
GREAT LAKES AND DIGS SOUTHWARD PUSHING A COLD FRONT INTO THE
CAROLINAS BY THE LATTER HALF OF NEXT WEEKEND. THIS WILL PROVIDE
LIMITED UPPER LEVEL SUPPORT FOR CONVECTION THROUGH THE WEEK INTO THE
FIRST HALF OF THE WEEKEND.
NOT EXPECTING ANY CHANGE IN AIR MASS THROUGH THE PERIOD WITH MAX
TEMPS UP AROUND 90 OR SO AND OVERNIGHT LOWS HOLDING UP AROUND 70 OR
SO. BUILDING H5 HEIGHTS THROUGH FRI SHOULD HELP KEEP TEMPS ABOVE
NORMAL AND WILL BEGIN A SLIGHT DOWNWARD TREND AS TROUGH MAKES ITS
WAY EAST INTO NEXT WEEKEND.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...CURRENT RADAR IMAGERY SHOWS A LINE OF SCT CONVECTION TO
OUR WEST ASSOCIATED WITH THE PIEDMONT TROUGH. THE HRRR SUGGESTS THIS
ACTIVITY WILL CONTINUE TO WEAKEN THIS EVENING. DO NOT ANTICIPATE ANY
IMPACTS TO KFLO/KLBT ATTM...OTHER THAN PERHAPS SOME INCREASED MID
LEVEL DEBRIS CLOUDS TONIGHT.
VERY SIMILAR PATTERN AS THE PAST COUPLE NIGHTS WITH BERMUDA HIGH
PRESSURE STILL STATIONED WELL OFFSHORE. EXPECT WINDS TO BECOME LIGHT
S-SW AOB 5 KT OVERNIGHT. SOME SCT 1-3KFT CLOUDS MAY SKIRT THE
COASTAL TERMS AGAIN EARLY MON WITH NOCTURNAL SHOWERS OFFSHORE...BUT
DO NOT EXPECT PERSISTENT MVFR CIGS TO DEVELOP. BEST CHANCE FOR IFR
OR LOWER CIGS/VSBYS WILL BE INLAND AT KFLO/KLBT...MOST LIKELY
BETWEEN 09-12Z. WILL INCLUDE TEMPO IFR VSBYS/LIFR CIGS FOR THESE
SITES AROUND DAYBREAK. VFR WILL PREVAIL DURING THE DAY MON WITH
SOUTHWEST WINDS AROUND 5 KT...BECOMING SOUTH AROUND 10 KT AT THE
COASTAL SITES FOLLOWING MIDDAY SEA BREEZE PASSAGE. SLIGHT CHANCE OF
AFTN SHOWERS/TSTMS DOES NOT WARRANT A TAF MENTION ATTM.
EXTENDED OUTLOOK...CHANCE OF ISOLATED TO SCATTERED AFTN SHOWERS AND
TSTMS THROUGH FRIDAY. PATCHES OF MVFR/IFR FOG OR STRATUS MAY ALSO
DEVELOP EACH MORNING. BUT OVERALL VFR CONDITIONS SHOULD PREVAIL.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM SUNDAY...HIGH PRESSURE OVER THE WESTERN ATLANTIC
WILL KEEP UP A STEADY SOUTHERLY FLOW OF AROUND 10 KTS THROUGH THE
NEAR TERM...WITH SEAS NOT STRAYING FAR FROM THEIR PRESENT 2 TO 3
FT RANGE.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...THE PRESSURE PATTERN ACROSS THE AREA WATERS
WILL BE THE RESULT OF THE INTERACTION BETWEEN RIDGING FROM THE
WESTERN ATLANTIC HIGH AND HE SFC PIEDMONT TROUGH. LOOKING AT
SYNOPTIC WINDS IN THE SSW THRU WSW WIND DIRECTION...WITH AN
OVERALL SLIGHT BACKING EACH AFTN AND EVENING FROM THE DIURNALLY
DRIVEN SEA BREEZE. THE SFC PG WILL BECOME MODEST AT BEST RESULTING
WITH 10-15 KT OR A SOLID 15 KT WIND SPEED. SIGNIFICANT SEAS WILL
RUN 2 TO OCCASIONALLY 3 FT...WITH MAJORITY OF THE SIG. SEAS A
RESULT OF THE 2 FOOT SE GROUND SWELL RUNNING ROUGHLY AT 9-10
SECOND PERIODS. WIND DRIVEN WAVES ESPECIALLY FROM THE SEA BREEZE
WILL RUN SIG. SEAS UP TO 3 TO POSSIBLY 4 FT.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 PM SUNDAY...HIGH PRESSURE WILL CONTINUE TO DOMINATE
WITH A RELAXED GRADIENT FLOW. OVERALL EXPECT WEAK SOUTHERLY FLOW
10 KTS OR LESS DOMINATED BY SEA/LAND BREEZE. WINDS WILL SPIKE UP
EACH AFTERNOON NEAR SHORE AS SEA BREEZE STRENGTHENS. SEAS WILL
REMAIN FAIRLY BENIGN WITH HEIGHTS LESS THAN 3 FT AND SLIGHT CHOP
IN THE AFTN SEA BREEZE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...REK
NEAR TERM...REK
SHORT TERM...DCH
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
257 AM EDT SAT AUG 30 2014
.SYNOPSIS...A WARM FRONT WILL RETREAT NORTHEASTWARD ACROSS CENTRAL
AND EASTERN NC AND VA TODAY. HIGH PRESSURE WILL BUILD ALOFT OVER
OUR REGION INTO MID-WEEK.
&&
.NEAR TERM /TONIGHT/...
AS OF 1030 PM FRIDAY...
TWO PRIMARY FORECAST CONCERNS FOR TONIGHT INVOLVE THE DEVELOPMENT OF
LOW STRATUS AND FOG...AND SHOWERS.
THE FORMER HAS A HIGHER PROBABILITY OF OCCURRENCE OWING TO A REGIME
OF ABUNDANT LOW LEVEL MOISTURE - CHARACTERIZED BY SFC DEWPOINTS IN
THE UPPER 60S TO MIDDLE 70S - THAT HAS POOLED INVOF THE FRONT
STALLED OVER SE NC...AND WHICH HAS SINCE BECOME TRAPPED IN THE
VERTICAL BY A SHALLOW INVERSION. LIGHT TO CALM SFC WIND AND
ASSOCIATED COOLING OF THE BOUNDARY LAYER...IN BETWEEN PERCOLATING
PATCHES OF 2-6 THOUSAND FT CLOUDINESS...SHOULD THEN SUPPORT THE
DEVELOPMENT AND EXPANSION OF LOW CLOUDS AND FOG. THE HRRR SUGGESTS
SOME FOG MAY BECOME DENSE IN PATCHES OVER THE SOUTHERN AND WESTERN
PIEDMONT...WHERE SFC WINDS HAVE BEEN...AND WILL CONTINUE TO
BE...RELATIVELY LIGHTER.
THE PROBABILITY OF SHOWERS IS LESS CERTAIN. THERE IS A QPF SIGNAL
FOR SHOWER DEVELOPMENT OVER THE NORTHERN PIEDMONT PER NEAR TERM
GUIDANCE FROM BOTH THE HRRR AND RUC...BUT FORCING FOR ASCENT AND
INSTABILITY TO DRIVE SUCH DEVELOPMENT...ARE EXPECTED TO BE VERY
WEAK. THE FORCING FOR ASCENT WILL COME COURTESY OF WEAK AND SHALLOW
ISENTROPIC UPGLIDE ATOP THE AFOREMENTIONED STALLED SFC FRONT
TONIGHT...AND RECENT REGIONAL VWP WINDS CORROBORATE THIS IDEA WITH
THEIR DEPICTION OF WEAK BUT VEERING WINDS IN THE LOWEST SEVERAL
THOUSAND FT. WILL INTRODUCE JUST A SLIGHT CHANCE OF A SHOWER
GENERALLY NORTH OF HIGHWAY 64 TO ACCOUNT FOR THIS POSSIBILITY.
LOWS GENERALLY 69 TO 75.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 250 PM FRIDAY...
CENTRAL NC WILL REMAIN UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE
ON SATURDAY. THE LINGERING BACKDOOR FRONT IS EXPECTED TO WASH OUT
DURING THE DAY AS THE SURFACE HIGH SHIFTS OFFSHORE AND A LIGHT
SOUTHERLY RETURN FLOW DEVELOPS ACROSS THE REGION. ALL OF THIS WILL
RESULT IN A TYPICAL SUMMERTIME PATTERN...WITH HIGHS RISING INTO THE
LOWER 90S. WITH MARGINAL INSTABILITY EXPECTED TO DEVELOP (HIGHEST
ACROSS THE SOUTHEAST)...ISOLATED DIURNAL CONVECTION WILL BE
POSSIBLE...ALTHOUGH MANY AREA LIKELY REMAINING DRY. OVERNIGHT LOWS
ARE EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
AS OF 257 AM SATURDAY...
UPPER RIDGING WILL PREVAIL FOR WHAT APPEARS TO BE THE FIRST REAL
"EXTENDED" TIME THIS SUMMER OVER NC. THEREFORE... ANY SURFACE FRONTS
APPROACHING FROM THE NORTH WILL HAVE A DIFFICULT TIME PUSHING THIS
FAR SOUTH... LIKELY STALLING OVER VA OR NEAR THE VA/NC BORDER. WE
WILL MAINTAIN A FORECAST THAT DEPICTS SLIGHTLY ABOVE CLIMATOLOGY FOR
HIGHS/LOWS... AND VERY NEAR CLIMATOLOGY FOR PM THUNDERSTORM CHANCES
(THE ONLY CHANCE OF RAINFALL IN THIS PATTERN) DURING SUMMER. EXPECT
DAILY HIGHS GENERALLY 88-94 NW TO SANDHILLS WITH LOWS 68-73. THESE
NUMBERS WILL BE 2-4 DEGREES ABOVE NORMAL. A DAILY CHANCE OF
CONVECTION IN THE AFTERNOON AND EARLY EVENING SHOULD BE LOWEST TUE
(15-20 PERCENT)... THEN PICK UP SLIGHTLY WED-FRI (30-40) PERCENT.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 819 PM FRIDAY...
CONDITIONS HAVE IMPROVED TO VFR AT ALL TERMINALS THIS EVENING. IFR
CONDITIONS WILL RETURN TO THE AREA OVERNIGHT... AS A FRONTAL
BOUNDARY REMAINS ACROSS THE AREA... WITH HIGH LOW LEVEL MOISTURE AND
LIGHT WIND. CONDITIONS WILL IMPROVE AFTER SUNRISE... AND RETURN TO
VFR DURING THE DAY SATURDAY AS THE BOUNDARY DISSIPATES.
OUTLOOK...A SUMMERTIME PATTERN WILL PERSIST THROUGH EARLY/MID NEXT
WEEK...WITH ISOLATED TO SCATTERED AFTERNOON/EVENING CONVECTION AND A
POTENTIAL FOR EARLY MORNING FOG/STRATUS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS/PWB
NEAR TERM...MWS
SHORT TERM...KRD
LONG TERM...PWB
AVIATION...SEC/KRD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1144 PM CDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 1140 PM CDT FRI AUG 29 2014
NO ADDITIONAL CHANGES NEEDED FROM PREVIOUS UPDATE.
UPDATE ISSUED AT 1008 PM CDT FRI AUG 29 2014
NOT UNEXPECTED...BUT CLEARING HAS SLOWED A BIT JUST A TAD SLOWER
THAN EARLIER RAP MODEL INDICATED. THUS BACKED OFF A LITTLE IN THE
GRIDS WITH TIMING. AVIATION TAFS APPEAR OK. DID ADD PATCHY FOG TO
DVL REGION AS GOOD RADIATIONAL COOLING WILL OCCUR THERE.
SURROUNDING OFFICES HAVE FOG MENTIONED AND DONT SEE ENOUGH OF AN
IN ISSUE AS CLEARING WILL ONLY SLOWLY PROGRESS SOUTH OVERNIGHT.
TEMPS OK. RADAR SHOWS A FEW SPRINKLES LEFTOVER AROUND BEMIDJI-
FOSSTON SO KEPT ISOLD -RW TIL 05Z IN THAT AREA.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 255 PM CDT FRI AUG 29 2014
CURRENT METARS SHOW THE SFC BNDRY MOVING ACROSS ND TODAY IS
LOCATED ROUGHLY OVER THE RED RIVER VALLY FROM HCO (MN) TO FAR.
SAT CONTINUING TO SHOW SKIES OVER THE UPPER SHEYENNE BASIN AND
JAMES VALLEY REGION BREAK UP. CURRENT RADAR SHOWS A SMALL CLUSTER
OF RAIN SHOWERS/VIRGA OVER CENTRAL ND. IMMEDIATE SHORT TERM MODELS
APPEAR TO BE OVERDOING PRECIP...SO WILL GO MOSTLY WITH
CONTINUITY/WX TRENDS VS ANY MODEL CHOICE. LATER IN THE PERIOD A
FRONT MOVES INTO WRN ND...WITH GFS FASTER THAN THE ECMWF ON
TIMING. WILL USE A FCST BLEND FOR THIS PD.
THIS AFTN AND TONIGHT....SFC BNDRY NOW EAST OF AREA OF CLEARING
AND MOVING INTO MN...WHERE SKIES HAVE BEEN CLOUDY ALL DAY AND
REGION HAS NOT HEATED OUT. OVERALL NOT AN IMPRESSIVE SITUATION AND
WILL KEEP IN THE LOW CHANCE POPS WITH RAIN SHOWERS AND ISOLD TSTMS
THE MAIN THREAT. COOLEST AREAS TONIGHT WILL BE ACROSS EASTERN ND
AND INTO FAR NWRN MN WHERE SKIES WILL LIKELY CLEAR AND TEMPS COULD
DROP INTO UPPER 40S ACROSS THIS REGION.
TOMORROW AND TOMORROW NIGHT...SHORT WAVE RIDGE ALOFT WILL BRING DRY
WEATHER TO THE REGION...HOWEVER A STRONG UPPER WAVE OVER PAC NW
WILL MOVE INTO MT WHILE LOW PRESSURE DEVELOPS OVER THE PLAINS. AN
OPEN GULF WILL ALLOW STRONG H850 MOISTURE FLUX INTO THE REGION BY
SATURDAY NIGHT. EXPECT SOME ELEVATED CONVECTION TO PICK UP BY LATE
SAT EVENING AND INCREASE AFT MIDNIGHT. HAVE LIKELY POPS INTO THE
WRN ZONES AFT 06Z...HOWEVER MAIN SHOW WILL BE DRG THE DAY SUNDAY
(SEE LONG RANGE DISCUSSION) AS SFC FRONT MOVES ACROSS DAKOTAS AND
INTO MN.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 255 PM CDT FRI AUG 29 2014
SUN AND SUN NIGHT...MODELS INDICATING EXTENDED AREA OF SFC
TROUGHING/FRONT FROM EASTERN DAKOTAS DOWN THROUGH SD/NE AND INTO
NW KS. SHORT WAVE PROGGED TO BE ENTERING WRN DAKOTAS FROM EASTERN
MT AT 12Z SUNDAY. GFS IS FASTER WITH THE UPPER WAVE ENTERING THE
DAKOTAS THAN IS THE ECMWF...AND ITS TIMING WILL BE CRITICAL ON SVR
POTENTIAL FOR SUN AFTN. GULF MOISTURE SHOULD BE READILY AVAILABLE
WITH BOTH MODELS SHOWING STRONG H850 MOISTURE FLUX INTO THE
CENTRAL AND EASTERN DAKOTAS SAT NIGHT COUPLED WITH 35 TO 45 KTS OF
0-6 KM BULK SHEAR. ASSOCIATED SFC FRONT PROGGED TO ENTER THE
EASTERN DAKOTAS (WESTERN CWA) LATE SUN MORNING AND MOVE ACROSS THE
VALLEY IN THE EARLY AFTN HOURS...EXTENDING ACROSS NW AND W CNTRL
MN BY MID AFTN. BULK SHEAR BY SUN AFTN EXPECTED TO INCREASE TO 40
KTS TO 50 KTS. WITH THESE INGREDIENTS IN PLACE...THERE IS
CERTAINLY A POTENTIAL FOR SVR ACROSS MINNESOTA ON SUN AFTN. SPC
HAS ISSUED A SLIGHT RISK FOR DAY 3. CONVECTION SHOULD BEGIN
TAPERING OFF BY MIDNIGHT SUN NIGHT AND MONDAY WILL BE DRY ACROSS
MAJORITY OF THE AREA.
FOR MON NIGHT THROUGH FRIDAY...THE PERIOD SHOULD START OUT MAINLY
DRY. THE CHANCES FOR SHOWERS AND SOME STORMS COULD INCREASE BY THE
MIDDLE TO END OF NEXT WEEK...WITH MORE CYCLONIC FLOW ALOFT
TRANSITIONING TO POTENTIAL SW FLOW ALOFT. THE EXACT TIMING OF
SHORTWAVES IS TOUGH...BUT WILL LEAVE IN MENTION OF MAINLY CHANCE
TYPE POPS FOR THE END OF NEXT WEEK...WITH THE DEEPER MOISTURE AND
SOME INSTABILITY CONFINED MAINLY TO THE SOUTHERN 2/3 OF THE FORECAST
AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1140 PM CDT FRI AUG 29 2014
INITIAL ISSUE WILL BE TIMING OF CLEARING OF THE IFR/MVFR CLOUDS AT
FARGO AND BEMIDJI TAF SITES. CLEARING MAKING ITS WAY INTO TVF/GFK
SITES ATTM AND WILL BE SCT-BKN AT TIMES 06Z-10Z PERIOD. WENT A BIT
MORE PESSIMISTIC AT FARGO-BEMIDJI AND KEPT IN MVFR CIGS AT FARGO
TIL JUST PAST DAYBREAK AND KEPT IFR AT BEMIDJI TIL PAST DAYBREAK
AS WELL AS COOL NORTH WINDS MOVE INTO THE MOIST AIRMASS AND MAIN
DRYING STAYS FURTHER NORTH AND WEST OF THIS REGION. OTHERWISE
LIGHT NORTH WINDS BECOMING SOUTHEAST SATURDAY AFTN-EVE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...SPEICHER
LONG TERM...DK/SPEICHER
AVIATION...RIDDLE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
641 AM EDT SAT AUG 30 2014
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS THE NORTHERN GREAT LAKES THIS
WEEKEND AND A COLD FRONT WILL MOVE TOWARD LAKE ERIE BUT THEN
BECOME STATIONARY ON SUNDAY. ANOTHER LOW WILL MOVE ACROSS THE LAKES
REGION MONDAY NIGHT AND A COLD FRONT WILL MOVE ACROSS THE AREA ON
TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS WILL BE IN THE INCREASE ESPECIALLY THIS AFTERNOON AS
SHOWERS AND THUNDERSTORMS START TO DEVELOP. CHANGED THE WORDING
OVER NW OH TO SCATTERED SHOWERS AND THUNDERSTORMS BASED ON THE
HRRR AND CURRENT RADAR TRENDS. STILL WATCHING FOR SOME SHOWERS TO
DEVELOP THIS AFTERNOON OVER NW PA BEFORE THEY DEVELOP OVER NE OH
BECAUSE OF SOME EXTRA MOISTURE MOVING UP THROUGH WESTERN PA. USED
A BLEND OF THE GUIDANCE FOR THE TEMPERATURE FORECAST AND USING THE
REASONING THAT NE OH WILL HAVE MORE SUNSHINE THEN NW OH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE WEEKEND WILL NOT BE A WASHOUT AND THE BEST CHANCE FOR RAIN
WILL BE SATURDAY NIGHT INTO SUNDAY.
THE POPS FOR TONIGHT ARE TOUGH. THE MODELS BRING IN MORE MOISTURE
OVERNIGHT AHEAD OF THE COLD FRONT THAT WILL NOT MAKE IT IN. BASED
ON THAT WENT WITH LIKELY POPS FOR THE NORTHERN PORTION OF THE
FORECAST AREA TONIGHT OR LATE TONIGHT AND THEN LIKELY OVER THE
SOUTHERN PORTION OF THE FORECAST AREA ON SUNDAY. CONDITIONS WILL
BE DRYING OUT FROM THE NORTH.
ON MONDAY THE REGION WILL BE IN A SOUTHWEST FLOW AND A WEAK
IMPULSE ALOFT IS EXPECTED TO MOVE THROUGH...THUS CONTINUED A 30 POP.
A COLD FRONT WILL BE APPROACHING THE AREA FOR MONDAY NIGHT INTO
TUESDAY. INCREASED THE POPS SOME BECAUSE OF THIS FEATURE.
AT THIS TIME SOME OF THE THUNDERSTORMS COULD BE STRONG TONIGHT
ESPECIALLY OVER EXTREME NW OH. THE PRECIPITABLE WATER VALUES GET
A LITTLE HIGH TONIGHT...SOME LOCALLY HEAVY RAIN IS POSSIBLE. MANY
AREAS HAVE DRIED OUT. HOWEVER...SOME LOCAL FLOOD ISSUES ARE
POSSIBLE. AT THIS TIME NO MENTION IN THE HAZARDOUS WEATHER OUTLOOK
BUT THAT MAY CHANGE.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
UPPER LEVEL RIDGE WILL MOVE EAST ACROSS THE AREA THROUGH THE PERIOD.
A MEDIOCRE SHORTWAVE TROUGH IS EXPECTED TO MOVE EAST ACROSS NORTHERN
AND CENTRAL CANADA BY FRIDAY BUT SHOULD REMAIN NORTH OF THE AREA.
THIS SHOULD KEEP A ZONAL FLOW PATTERN GOING THROUGH THE DURATION.
SURFACE HIGH PRESSURE OVER THE FORECAST AREA WILL MOVE EAST OF THE
REGION AND BE OFF THE ATLANTIC COAST BY FRIDAY. THIS TRANSITION WILL
BRING A RETURN SOUTHERLY FLOW INTO THE FORECAST AREA ALONG WITH MORE
STRONG WARM AIR ADVECTION. MID LEVEL AND SURFACE AIR WILL TRACK
RIGHT UP OUT OF THE PANHANDLE OF OKLAHOMA TOWARD THE END OF THE
WEEK. A COLD FRONT IS PROGGED TO MOVE EAST INTO THE AREA BY FRIDAY
EVENING AND BECOME NEARLY STATIONARY. SOME LIMITED MOISTURE
ASSOCIATED WITH THE FRONT WILL BRING WITH IT THE BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS FRIDAY. SCATTERED AFTERNOON CONVECTION IS
POSSIBLE THE REST OF THE DAYS ON THE WEST SIDE OF THE HIGH PRESSURE
CENTER.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
UPPER LEVEL RIDGE STILL IN PLACE OVER THE FORECAST AREA AT THIS
TIME. A LONE SHOWER MOVED NORTH BUT REMAINED JUST EAST OF THE
TOLEDO AND FINDLAY TAF SITES. EXPECTING A POSSIBILITY FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN PORTIONS OF THE
REGION. LATEST HRRR MODEL IS SHOWING A THREAT FOR AN ISOLATED
SHOWER TO MOVE NORTHEAST ALONG THE LAKE SHORE FROM CLEVELAND TO
ERIE EARLY THIS AFTERNOON. BUT WILL LEAVE THINGS DRY AT ERIE AT
THIS POINT SINCE IT WILL BE SO WIDELY SCATTERED IF IT OCCURS.
OTHERWISE DRY FOR THE REST OF THE TAF SITES. WINDS WILL BE ON THE
INCREASE LATER TONIGHT FROM THE SOUTH AS WELL. EARLIER FORECAST
MENTIONED SOME WIND SHEAR. LATEST GUIDANCE NOW SUGGESTS WINDS WILL
GRADUALLY INCREASE FROM 10 KNOTS AT THE SURFACE TO 40 KNOTS AT
2000 FEET SO NOT EXPECTING WIND SHEAR AT THIS TIME.
OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS SATURDAY
THROUGH TUESDAY AT TIMES.
&&
.MARINE...
FAIRLY DESCENT FLOW WILL DEVELOP LATER TONIGHT OUT OF THE SOUTHWEST
AND COULD POSSIBLY BE STRONG ENOUGH TO SUPPORT SMALL CRAFT ADVISORY
CRITERIA FOR A PERIOD OF TIME. EXPECTING WINDS TO DIMINISH ON SUNDAY
TO LIGHT SOUTH TO SOUTHWEST AND THEN INCREASE AGAIN BY MONDAY NIGHT
AHEAD OF THE NEXT COLD FRONT. OTHERWISE...WINDS LOOK FAIRLY LIGHT
GOING INTO WEDNESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
403 AM EDT SAT AUG 30 2014
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS THE NORTHERN GREAT LAKES THIS
WEEKEND AND A COLD FRONT WILL MOVE TOWARD LAKE ERIE BUT THEN
BECOME STATIONARY ON SUNDAY. ANOTHER LOW WILL MOVE ACROSS THE LAKES
REGION MONDAY NIGHT AND A COLD FRONT WILL MOVE ACROSS THE AREA ON
TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SHOWER THAT MOVED ACROSS THE WESTERN PORTION OF THE FORECAST
AREA DURING THE EARLY MORNING WAS OVER THE LAKE AND CONTINUING TO
MOVE NORTHEAST. THE MORNING SHOULD BE DRY AS WE WAIT FOR A THREAT
OF SHOWERS AND THUNDERSTORMS TO DEVELOP AHEAD OF THE COLD FRONT
OVER NW OH AND POSSIBLY OVER NW PA AS SOME MOISTURE MOVES UP
THROUGH WESTERN PA. THE HIGH TEMPERATURE FORECAST IS TOUGH
DEPENDING ON THE CLOUD COVER AND HOW QUICKLY ANY SHOWERS OR
THUNDERSTORMS DEVELOP. USED A BLEND OF THE GUIDANCE FOR THE
TEMPERATURE FORECAST AND USING THE REASONING THAT NE OH WILL HAVE
MORE SUNSHINE THEN NW OH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE WEEKEND WILL NOT BE A WASHOUT AND THE BEST CHANCE FOR RAIN
WILL BE SATURDAY NIGHT INTO SUNDAY.
THE POPS FOR TONIGHT ARE TOUGH. THE MODELS BRING IN MORE MOISTURE
OVERNIGHT AHEAD OF THE COLD FRONT THAT WILL NOT MAKE IT IN. BASED
ON THAT WENT WITH LIKELY POPS FOR THE NORTHERN PORTION OF THE
FORECAST AREA TONIGHT OR LATE TONIGHT AND THEN LIKELY OVER THE
SOUTHERN PORTION OF THE FORECAST AREA ON SUNDAY. CONDITIONS WILL
BE DRYING OUT FROM THE NORTH.
ON MONDAY THE REGION WILL BE IN A SOUTHWEST FLOW AND A WEAK
IMPULSE ALOFT IS EXPECTED TO MOVE THROUGH...THUS CONTINUED A 30 POP.
A COLD FRONT WILL BE APPROACHING THE AREA FOR MONDAY NIGHT INTO
TUESDAY. INCREASED THE POPS SOME BECAUSE OF THIS FEATURE.
AT THIS TIME SOME OF THE THUNDERSTORMS COULD BE STRONG TONIGHT
ESPECIALLY OVER EXTREME NW OH. THE PRECIPITABLE WATER VALUES GET
A LITTLE HIGH TONIGHT...SOME LOCALLY HEAVY RAIN IS POSSIBLE. MANY
AREAS HAVE DRIED OUT. HOWEVER...SOME LOCAL FLOOD ISSUES ARE
POSSIBLE. AT THIS TIME NO MENTION IN THE HAZARDOUS WEATHER OUTLOOK
BUT THAT MAY CHANGE.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
UPPER LEVEL RIDGE WILL MOVE EAST ACROSS THE AREA THROUGH THE PERIOD.
A MEDIOCRE SHORTWAVE TROUGH IS EXPECTED TO MOVE EAST ACROSS NORTHERN
AND CENTRAL CANADA BY FRIDAY BUT SHOULD REMAIN NORTH OF THE AREA.
THIS SHOULD KEEP A ZONAL FLOW PATTERN GOING THROUGH THE DURATION.
SURFACE HIGH PRESSURE OVER THE FORECAST AREA WILL MOVE EAST OF THE
REGION AND BE OFF THE ATLANTIC COAST BY FRIDAY. THIS TRANSITION WILL
BRING A RETURN SOUTHERLY FLOW INTO THE FORECAST AREA ALONG WITH MORE
STRONG WARM AIR ADVECTION. MID LEVEL AND SURFACE AIR WILL TRACK
RIGHT UP OUT OF THE PANHANDLE OF OKLAHOMA TOWARD THE END OF THE
WEEK. A COLD FRONT IS PROGGED TO MOVE EAST INTO THE AREA BY FRIDAY
EVENING AND BECOME NEARLY STATIONARY. SOME LIMITED MOISTURE
ASSOCIATED WITH THE FRONT WILL BRING WITH IT THE BEST CHANCE FOR
SHOWERS AND THUNDERSTORMS FRIDAY. SCATTERED AFTERNOON CONVECTION IS
POSSIBLE THE REST OF THE DAYS ON THE WEST SIDE OF THE HIGH PRESSURE
CENTER.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
UPPER LEVEL RIDGE STILL IN PLACE OVER THE FORECAST AREA AT THIS
TIME. A LONE SHOWER MOVED NORTH BUT REMAINED JUST EAST OF THE
TOLEDO AND FINDLAY TAF SITES. EXPECTING A POSSIBILITY FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN PORTIONS OF THE
REGION. LATEST HRRR MODEL IS SHOWING A THREAT FOR AN ISOLATED
SHOWER TO MOVE NORTHEAST ALONG THE LAKE SHORE FROM CLEVELAND TO
ERIE EARLY THIS AFTERNOON. BUT WILL LEAVE THINGS DRY AT ERIE AT
THIS POINT SINCE IT WILL BE SO WIDELY SCATTERED IF IT OCCURS.
OTHERWISE DRY FOR THE REST OF THE TAF SITES. WINDS WILL BE ON THE
INCREASE LATER TONIGHT FROM THE SOUTH AS WELL. EARLIER FORECAST
MENTIONED SOME WIND SHEAR. LATEST GUIDANCE NOW SUGGESTS WINDS WILL
GRADUALLY INCREASE FROM 10 KNOTS AT THE SURFACE TO 40 KNOTS AT
2000 FEET SO NOT EXPECTING WIND SHEAR AT THIS TIME.
OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS SATURDAY
THROUGH TUESDAY AT TIMES.
&&
.MARINE...
FAIRLY DESCENT FLOW WILL DEVELOP LATER TONIGHT OUT OF THE SOUTHWEST
AND COULD POSSIBLY BE STRONG ENOUGH TO SUPPORT SMALL CRAFT ADVISORY
CRITERIA FOR A PERIOD OF TIME. EXPECTING WINDS TO DIMINISH ON SUNDAY
TO LIGHT SOUTH TO SOUTHWEST AND THEN INCREASE AGAIN BY MONDAY NIGHT
AHEAD OF THE NEXT COLD FRONT. OTHERWISE...WINDS LOOK FAIRLY LIGHT
GOING INTO WEDNESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...LOMBARDY
AVIATION...LOMBARDY
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
128 AM EDT SAT AUG 30 2014
.SYNOPSIS...
AS THE SURFACE HIGH OVER NEW YORK MOVES EAST IT WILL ALLOW AN AREA
OF LOW PRESSURE OVER THE NORTHERN PLAINS TO MOVE INTO THE GREAT
LAKES. AS IT APPROACHES THE LOCAL AREA WE WILL SEE AN INCREASE IN
CLOUDS AND STORM ACTIVITY STARTING FROM WEST TO EAST LATE
SATURDAY. ANOTHER LOW PRESSURE SYSTEM WILL MOVE OVER THE LAKES
REGION MONDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ADDED A THREAT OF SHOWERS TO THE WESTERN PORTION OF THE FORECAST
AREA AS PER THE RADAR. IT SHOULD DECREASE. ELSEWHERE PARTLY CLOUDY
SHOULD BE OK. MADE MINOR ADJUSTMENTS TO SOME OF THE LOWS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
A DISTURBANCE FROM THE WEST WILL APPROACH THE REGION ON SATURDAY.
THE BEST CHANCE FOR CONVECTION WILL BE IN THE AFTERNOON...BUT
COULD SEE SOME STRAY STORMS IN THE FAR WEST BEFORE NOON. FOCUS
FOR THE GREATEST COVERAGE WILL BE OVER THE WESTERN HALF OF THE
FORECAST AREA WHERE MOISTURE AND INSTABILITY WILL BE GREATER. THE
MODELS ARE SUGGESTING SOME MOISTURE WILL BECOME AVAILABLE IN THE
FAR EASTERN COUNTIES AS IT WRAPS AROUND THE BACKSIDE OF THE SFC
HIGH..BUT NOT CONVINCED THIS WILL BE ENOUGH WHEN COMBINED WITH A
WEAK CAP TO GENERATE STORMS FOR THE FIRST HALF OF THE DAY. THERE
IS SOME SUGGESTION THAT THERE WILL BE A DRY SLOT BETWEEN THE TWO
SYSTEMS KEEPING PLENTY OF SUNSHINE AND DRY CONDITIONS OVER THE
EASTERN 2/3RDS OF THE CWA. TEMPERATURES WILL BE ABLE TO CLIMB INTO
THE MID/UPPER 80S ACROSS THE REGION...WELL ABOVE THE UPPER 70
NORMALS FOR THIS TIME OF YEAR. THIS COMBINED WITH HIGH DEW POINTS
WILL MAKE HEAT INDEX VALUES IN THE UPPER 80S TO NEAR 90. THE JET
DYNAMICS BECOME FAVORABLE LATER IN THE AFTERNOON AND GRADUALLY
IMPROVES EAST INTO THE EVENING HOURS WITH INCREASED FORCING AND
PLENTIFUL MOISTURE. WITH THE UPPER TROUGH PASSING OVER THE AREA
SUNDAY WE WILL SEE A LOWERING OF POPS FROM NW WITH REDUCED
FORCING. THE RAIN CHANCES WILL LINGER FOR THE BETTER PART OF THE
DAY OVER THE SOUTHEAST COUNTIES...WHERE THE MAIN THREAT WILL BE
THE HEAVY RAIN WITH PW VALUES AROUND 1.8". POPS SUNDAY NIGHT WILL
DROP AND THERE WILL BE A PERIOD WITHOUT STORMS THROUGH THE FIRST
HALF OF LABOR DAY. THE SECOND UPPER TROUGH WILL MOVE INTO THE AREA
FROM THE PLAINS MONDAY NIGHT. IN ADVANCE OF THIS SYSTEM WE COULD
SEE SOME SCATTERED STORMS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
JET STREAM CONTINUES TO TRACK ZONALLY ACROSS THE NORTHERN TIER
STATES TAKING A SYSTEM ACROSS THE GREAT LAKES TUESDAY. THIS FRONT
WILL MAKE LITTLE SOUTHERN PROGRESS LIKELY DISSIPATING OVER THE OHIO
VALLEY. SURFACE HIGH PRESSURE WEAKLY IN CONTROL WEDNESDAY AND
THURSDAY. ANOTHER SYSTEM WILL BE ON DECK FOR FRIDAY. OVERALL DECENT
MODEL AGREEMENT...BUT WITH THE ZONAL FLOW TIMING MAY BE OFF THIS FAR
OUT. CENTERED PRECIP CHANCES AROUND FRONTAL ZONES. TEMPERATURES WILL
RUN NEAR NORMAL.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
UPPER LEVEL RIDGE STILL IN PLACE OVER THE FORECAST AREA AT THIS
TIME. A LONE SHOWER MOVED NORTH BUT REMAINED JUST EAST OF THE
TOLEDO AND FINDLAY TAF SITES. EXPECTING A POSSIBILITY FOR SHOWERS
AND THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN PORTIONS OF THE
REGION. LATEST HRRR MODEL IS SHOWING A THREAT FOR AN ISOLATED
SHOWER TO MOVE NORTHEAST ALONG THE LAKE SHORE FROM CLEVELAND TO
ERIE EARLY THIS AFTERNOON. BUT WILL LEAVE THINGS DRY AT ERIE AT
THIS POINT SINCE IT WILL BE SO WIDELY SCATTERED IF IT OCCURS.
OTHERWISE DRY FOR THE REST OF THE TAF SITES. WINDS WILL BE ON THE
INCREASE LATER TONIGHT FROM THE SOUTH AS WELL. EARLIER FORECAST
MENTIONED SOME WIND SHEAR. LATEST GUIDANCE NOW SUGGESTS WINDS WILL
GRADUALLY INCREASE FROM 10 KNOTS AT THE SURFACE TO 40 KNOTS AT
2000 FEET SO NOT EXPECTING WIND SHEAR AT THIS TIME.
OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS SATURDAY
THROUGH TUESDAY AT TIMES.
&&
.MARINE...
THUNDERSTORMS AND A CHOPPY LAKE SATURDAY NIGHT/SUNDAY ARE THE MAIN
CONCERNS FOR THE MARINE FORECAST. AS HIGH PRESSURE SHIFTS EAST
TONIGHT WINDS ON THE LAKE WILL BECOME SOUTHERLY FOR SATURDAY...AND
THEN SOUTH-SOUTHWEST FOR SATURDAY NIGHT. THERE IS A LITTLE BIT OF
WIND FORECAST FOR SATURDAY NIGHT INTO SUNDAY...WITH SPEEDS OF 10 TO
20 KNOTS ON THE LAKE. THIS WILL RESULT IN A CHOPPY LAKE...WITH THE
POSSIBILITY OF NEEDING A SMALL CRAFT ADVISORY. THUNDERSTORM CHANCES
ARE FOCUSED PRIMARILY ON SATURDAY EVENING AND SATURDAY
NIGHT...CLEARING OUT ON SUNDAY. A COLD FRONT NEVER REALLY CROSSES
THE LAKE THIS WEEKEND...BUT INSTEAD WEAKENS OVERHEAD. LIGHTER
SOUTHWEST FLOW CONTINUES SUNDAY AND MONDAY. A COLD FRONT THAT SHOULD
CROSS THE LAKE ARRIVES FOR TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JAMISON
NEAR TERM...KIELTYKA
SHORT TERM...JAMISON
LONG TERM...OUDEMAN
AVIATION...LOMBARDY
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1010 PM EDT SUN AUG 31 2014
.SYNOPSIS...
A WARM AND HUMID SOUTHWEST FLOW WILL KEEP THE CHANCES FOR RAIN IN
THE FORECAST THROUGH THE LABOR DAY HOLIDAY. A COLD FRONT WILL
BRING A BREAK IN THE HUMIDITY FOR MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPPER SHEAR AXIS SLIDING ACROSS CENTRAL PA THIS EVENING...
DEEPEST MOISTURE AND MOST ACTIVE CONVECTION REMAINS SOUTHEAST OF
YORK AND LANCASTER COUNTIES THIS EVENING IN A LINE FROM NORTHERN
VA TO CENTRAL NJ. SOUPY AIR MASS REMAINS...FEATURING PW BETWEEN
1.75" AND 2.00" ACROSS THE SOUTHERN HALF OF THE COMMONWEALTH. DEEP
LAYER MOISTURE DROPS OFF TO 1.6" VALUES ACROSS THE NORTHWEST
MOUNTAINS.
TAIL END OF AFOREMENTIONED UPPER TROUGH/SHEAR AXIS LIFTING FROM
THE CENTRAL APPALACHIANS WILL REACH N CENTRAL MARYLAND BY 12Z
MON...CONTINUING SHOWER AND ISOLD THUNDERSTORM CHANCES
THERE. THE POSSIBILITY OF A STRIPE OF HEAVY RAINFALL FROM
NORTHERN VIRGINIA NEWD TO CENTRAL OR SOUTHERN NJ EXISTS...WHICH
COULD BRUSH MY SOUTHEAST COUNTIES. RUN TO RUN CONSISTENCY OF THE
LOCATION OF SAID HEAVY RAINFALL STRIPE IN THE NAM12 HAS BEEN
ATTROCIOUS...BUT EVEN THE LATEST HRRR IS SUPPORTIVE OF SUCH A
BAND.
OVERALL...MODEL CONSENSUS FAVORS A SOLUTION SOUTH AND EAST OF THE
LOWER SUSQ BUT WILL KEEP HIGHER POPS IN THAT REGION THROUGH LATE
TONIGHT AND EARLY MONDAY GIVEN THE FORCING AND AVAILABILITY OF
2.00" PW FROM THE DEL MARVA REGION TO THE SOUTHEAST PIEDMONT
REGION. AN ISOLATED SOMEBODY IN THOSE AREAS CAN SEE A FEW OR MORE
INCHES OF RAIN OVERNIGHT...BUT CENTRAL PA APPEARS AT THIS TIME TO
BE FAR ENOUGH NORTH TO AVOID IT ACROSS THE LOWER SUSQ.
PLENTY OF LOW LEVEL MOISTURE WILL BRING SOME POTENTIALLY DENSE
FOG AND LOW CIGS TO CENTRAL AND NORTHERN COUNTIES OVERNIGHT INTO
EARLY MON.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
HIGH PWAT AIR REMAINS IN PLACE ON MONDAY. THOUGH ENVIRONMENT NOT
AS FAVORABLE FOR WIDESPREAD RAINS WITH RISING UPPER HEIGHTS AND
WEAK SHORTWAVE RIDGING...SCT SHOWERS AND ISO TSTMS WILL HAVE TO
REMAIN IN THE FORECAST. DOESN/T LOOK LIKE A WASHOUT THOUGH. HIGHS
WILL BE 3-5F ABOVE NORMAL ALONG WITH HIGHER HUMIDITY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
OPERATIONAL MODELS CONTINUE TO SHOW A COLD FRONT SWINGING THROUGH
THE STATE LATE TUESDAY. THIS WILL BRING A HEALTHY DOSE OF RAIN TO
THE REGION...WITH SREF PLUME DIAGRAMS SHOWING UP TO ONE INCH OF
PRECIP. HIGH PRESSURE WILL THEN BUILD IN FOR MIDWEEK...BRINGING A
FEW DAYS OF MILD AND DRY WEATHER. AS THE HIGH MOVES OFF THE COAST
LATE IN THE WEEK...MORE HUMID FLOW AND THE CHANCE OF RAIN WILL
RETURN TO THE REGION. AT THIS POINT...THERE IS RELATIVELY GOOD
CONSENSUS BETWEEN MODELS ON A COLD FRONT MOVING THROUGH PENNSYLVANIA
SATURDAY BEFORE A COOLER AIRMASS MOVES OVER THE REGION FOR THE
SECOND HALF OF THE WEEKEND.
THIS UPCOMING WEEK WILL BE ONE OF THE RARE EXTENDED PERIODS OF
WARMER THAN NORMAL TEMPERATURES WE HAVE SEEN THIS SUMMER. HIGH
TEMPERATURES WILL CLIMB TO ALMOST 90 ACROSS THE SOUTH AND EAST ON
TUESDAY AHEAD OF THE FRONTAL PASSAGE. THEN AN UPPER RIDGE WILL BUILD
OVER THE EASTERN US FOR THE SECOND HALF OF THE WEEK...KEEPING HIGH
TEMPERATURES AT OR SLIGHTLY ABOVE SEASONAL NORMALS FOR EARLY
SEPTEMBER THROUGH SATURDAY.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHOWERS HAVE DISSIPATED AS BEST MOISTURE GETTING SHOVED TO THE
EAST AND FOCUS IS ALONG A SFC TROUGH JUST TO THE SE OF THE
AREA...AND IS FORECAST TO STAY RIGHT THERE. LNS MAY BE DEALING
WITH SHRA FOR THE OVERNIGHT...BUT MOST OTHER LOCATIONS SHOULD NOT.
HOWEVER...WITH THE VERY MOIST AIR - NEAR 70 DEWPOINTS - AND LIGHT
WIND...MANY LOCATIONS SHOULD SEE LOW CLOUDS AND FOG FORM EARLY
TONIGHT AND CONTINUE PAST SUNRISE. HAVE BROUGHT MANY TERMINALS
DOWN TO IFR CIGS AND VSBY. BFD ALREADY THERE...AND WHILE IT MAY
CLEAR THERE...IT WILL ONLY LEAD TO FOG. A LITTLE DRIZZLE IS
POSSIBLE IN THE EARLY MORNING...AND SCT SHRA/TSRA ALSO POSS IN THE
SRN TERMINALS FROM MID-DAY AND ON...BUT MOST ACTIVITY SHOULD STAY
TO THE SOUTH ALONG THAT BOUNDARY. WILL JUST GO WITH IMPROVING
CONDITIONS FOR THE DAY ON MONDAY.
COLD FRONT WITH DRYING EXPECTED TO PASS THROUGH NW-SE ON TUESDAY
WITH TSRA IN THE AFTN/EVENING.
OUTLOOK...
WED-THU...PATCHY AM FOG POSS. OTHERWISE VFR.
FRI...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/RXR
NEAR TERM...DEVOIR/RXR
SHORT TERM...COLBERT
LONG TERM...COLBERT
AVIATION...DANGELO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1009 PM EDT SUN AUG 31 2014
.SYNOPSIS...
A WARM AND HUMID SOUTHWEST FLOW WILL KEEP THE CHANCES FOR RAIN IN
THE FORECAST THROUGH THE LABOR DAY HOLIDAY. A COLD FRONT WILL
BRING A BREAK IN THE HUMIDITY FOR MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPPER SHEAR AXIS SLIDING ACROSS CENTRAL PA THIS EVENING...
DEEPEST MOISTURE AND MOST ACTIVE CONVECTION REMAINS SOUTHEAST OF
YORK AND LANCASTER COUNTIES THIS EVENING IN A LINE FROM NORTHERN
VA TO CENTRAL NJ. SOUPY AIR MASS REMAINS...FEATURING PW BETWEEN
1.75" AND 2.00" ACROSS THE SOUTHERN HALF OF THE COMMONWEALTH. DEEP
LAYER MOISTURE DROPS OFF TO 1.6" VALUES ACROSS THE NORTHWEST
MOUNTAINS.
TAIL END OF AFOREMENTIONED UPPER TROUGH/SHEAR AXIS LIFTING FROM
THE CENTRAL APPALACHIANS WILL REACH N CENTRAL MARYLAND BY 12Z
MON...CONTINUING SHOWER AND ISOLD THUNDERSTORM CHANCES
THERE. THE POSSIBILITY OF A STRIPE OF HEAVY RAINFALL FROM
NORTHERN VIRGINIA NEWD TO CENTRAL OR SOUTHERN NJ EXISTS...WHICH
COULD BRUSH MY SOUTHEAST COUNTIES. RUN TO RUN CONSISTENCY OF THE
LOCATION OF SAID HEAVY RAINFALL STRIPE IN THE NAM12 HAS BEEN
ATTROCIOUS...BUT EVEN THE LATEST HRRR IS SUPPORTIVE OF SUCH A
BAND.
OVERALL...MODEL CONSENSUS FAVORS A SOLUTION SOUTH AND EAST OF THE
LOWER SUSQ BUT WILL KEEP HIGHER POPS IN THAT REGION THROUGH LATE
TONIGHT AND EARLY MONDAY GIVEN THE FORCING AND AVAILABILITY OF
2.00" PW FROM THE DEL MARVA REGION TO THE SOUTHEAST PIEDMONT
REGION. AN ISOLATED SOMEBODY IN THOSE AREAS CAN SEE A FEW OR MORE
INCHES OF RAIN OVERNIGHT...BUT CENTRAL PA APPEARS AT THIS TIME TO
BE FAR ENOUGH NORTH TO AVOID IT ACROSS THE LOWER SUSQ.
PLENTY OF LOW LEVEL MOISTURE WILL BRING SOME POTENTIALLY DENSE
FOG AND LOW CIGS TO CENTRAL AND NORTHERN COUNTIES OVERNIGHT INTO
EARLY MON.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
HIGH PWAT AIR REMAINS IN PLACE ON MONDAY. THOUGH ENVIRONMENT NOT
AS FAVORABLE FOR WIDESPREAD RAINS WITH RISING UPPER HEIGHTS AND
WEAK SHORTWAVE RIDGING...SCT SHOWERS AND ISO TSTMS WILL HAVE TO
REMAIN IN THE FORECAST. DOESN/T LOOK LIKE A WASHOUT THOUGH. HIGHS
WILL BE 3-5F ABOVE NORMAL ALONG WITH HIGHER HUMIDITY.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
OPERATIONAL MODELS CONTINUE TO SHOW A COLD FRONT SWINGING THROUGH
THE STATE LATE TUESDAY. THIS WILL BRING A HEALTHY DOSE OF RAIN TO
THE REGION...WITH SREF PLUME DIAGRAMS SHOWING UP TO ONE INCH OF
PRECIP. HIGH PRESSURE WILL THEN BUILD IN FOR MIDWEEK...BRINGING A
FEW DAYS OF MILD AND DRY WEATHER. AS THE HIGH MOVES OFF THE COAST
LATE IN THE WEEK...MORE HUMID FLOW AND THE CHANCE OF RAIN WILL
RETURN TO THE REGION. AT THIS POINT...THERE IS RELATIVELY GOOD
CONSENSUS BETWEEN MODELS ON A COLD FRONT MOVING THROUGH PENNSYLVANIA
SATURDAY BEFORE A COOLER AIRMASS MOVES OVER THE REGION FOR THE
SECOND HALF OF THE WEEKEND.
THIS UPCOMING WEEK WILL BE ONE OF THE RARE EXTENDED PERIODS OF
WARMER THAN NORMAL TEMPERATURES WE HAVE SEEN THIS SUMMER. HIGH
TEMPERATURES WILL CLIMB TO ALMOST 90 ACROSS THE SOUTH AND EAST ON
TUESDAY AHEAD OF THE FRONTAL PASSAGE. THEN AN UPPER RIDGE WILL BUILD
OVER THE EASTERN US FOR THE SECOND HALF OF THE WEEK...KEEPING HIGH
TEMPERATURES AT OR SLIGHTLY ABOVE SEASONAL NORMALS FOR EARLY
SEPTEMBER THROUGH SATURDAY.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
STEADY PRECIPITATION TRANSITIONING TO A MORE CONVECTIVE
ENVIRONMENT AS WEAK TROUGH LIFTS INTO NEW ENGLAND WHILE CORE OF
JET SLIPS ACROSS EASTERN PA...TAPPING INTO MUGGY AND MOST UNSTABLE
AIR OVER SE PA. THIS REGION HAS SEEN SOME SUNSHINE TODAY...AND
MAIN FOCUS OF STRONG TSTMS LATE THIS AFTERNOON MAY CATCH OUR SE
CORNER /IN VICINITY OF KMDT-KLNS/ AND POINTS S AND E. FORECAST
MID LEVEL LAPSE RATES ARE WEAK BUT SHEAR INCREASING WHICH IS
AIDING IN SOME MORE ORGANIZED STORM DEVELOPMENT.
REMAINDER OF CWA WILL SEE MVFR TO VFR CIGS ALONG WITH SCATTERED
SHOWERS/ISOLATED TSTMS CONTINUE INTO THE EVENING HOURS...WITH A
GRADUAL DIMINISHING OF THE ACTIVITY LATE THIS AFTERNOON AND THIS
EVE.
TONIGHT...MAIN ACTIVITY WILL CONTINUE TO BE IN VICINITY OF MY SE
COUNTIES AS ANOTHER SHORTWAVE SLIDES UP THE APPALACHIANS AND MAY
KEEP SHOWERS/TSTM IMPACTS ONGOING INTO THE OVERNIGHT. PLENTY OF
LOW LEVEL MOISTURE WILL BRING MVFR TO IFR REDUCTIONS OVERNIGHT
INTO EARLY MONDAY WITH LOW CLOUDS AND SOME POTENTIALLY WIDESPREAD
DENSE FOG.
OUTLOOK...
MON...AM FOG POSS...ESP W MTNS. ISOLD PM TSRA IMPACTS
POSS.
TUE...SCT PM TSRA IMPACTS POSS.
WED...PATCHY AM FOG POSS.
THU...PATCHY AM FOG POSS.
FRI...NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/RXR
NEAR TERM...DEVOIR/RXR
SHORT TERM...
LONG TERM...COLBERT
AVIATION...RXR
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
916 PM CDT SUN AUG 31 2014
.UPDATE...
PRECIPITATION HAS BEEN CONFINED TO THE WESTERN PART OF THE CWA
THIS EVENING...WITH MORE ACTIVITY DEVELOPING ACROSS CENTRAL NORTH
DAKOTA. HAVE ADJUSTED POPS TO FIT THE CURRENT SITUATION...AND WILL
LEAVE A SLIGHT CHANCE MENTION ELSEWHERE IN CASE ANYTHING DRIFTS
DOWN FROM THE NORTH DURING THE OVERNIGHT HOURS. NO CHANGES MADE TO
WINDS OR TEMPERATURES AT THIS TIME.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
POTENT SHORTWAVE EVIDENT ON WATER VAPOR OVER WYOMING. AHEAD OF
THIS WAVE...OMEGA AND UPPER JET MAX HELPING TO MAINTAIN BAND OF
RAINFALL THAT HAS TREKKED FROM SOUTH CENTRAL SD TO NORTHEAST SD
OVER THE PAST SEVERAL HOURS. HAVE BEEN ADJUSTING POPS FOR THIS
BAND OF RAIN AS IT APPEARS IT WILL SURVIVE MOST IF NOT ALL THE WAY
ACROSS THE CWA. HRRR PICKING UP ON THIS QUITE NICELY.
OVERNIGHT...EXPECTING SCATTERED SHOWERS AND STORMS TO MOVE EAST
ACROSS THE STATE BUT WITH MINIMAL SEVERE THREAT DUE TO LACK OF
INSTABILITY. ONLY QUESTION IS THE DEGREE OF AREAL COVERAGE OF
PRECIP. SOME MODELS GREATER THAN OTHERS...WITH THE HRRR
PARTICULARLY DRY AND SORT OF THE OUTLIER. MOST OTHER MODELS HAVE
ACTIVITY MOVING ACROSS AT LEAST THE SOUTHERN HALF OF SD TONIGHT.
HAVE ADJUSTED POPS ACCORDINGLY AND LINGERED THEM A BIT LONGER
THROUGH THE NIGHT AS NSSL WRF STILL SHOWS CONVECTIVE CLUSTERS OVER
SOUTHEAST SD AT 09Z TONIGHT.
A WEAKER WAVE MOVES ACROSS THE AREA MONDAY...BUT SHOULD STILL
PROVIDE FOR A FEW SCATTERED SHOWERS OR STORMS. AREAL COVERAGE DOES
NOT APPEAR IT WILL QUITE MATCH UP TO WHATS MOVING INTO WESTERN SD
RIGHT NOW...BUT WORTHY OF 20/30 POPS NONETHELESS. AGAIN A LACK OF
INSTABILITY TOMORROW SO SEVERE THREAT IS VERY LOW.
TUESDAY STILL LOOKS DRY WITH NO NOTABLE SYSTEMS IN THE AREA. 500
MB HEIGHTS RISE SLOWLY THROUGH THE DAY WITH WARM AIR ADVECTION
DEVELOPING. HIGHS WILL BUMP UP INTO THE UPPER 70S TO LOW 80S FOR
MOST AREAS.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
THE EARLY PART OF THE PERIOD STARTS OFF SOMEWHAT ACTIVE AS FAIRLY
STRONG SYSTEM MOVES ACROSS THE NORTHERN PLAINS. LATEST MODELS ARE
IN FAIR AGREEMENT ON AVAILABLE MOISTURE/INSTABILITY BUT DO SUGGEST
CAPPING MIGHT FORCE MOST ACTIVITY TO REMAIN NORTH OF THE CWA
WEDNESDAY NIGHT INTO THURSDAY AS COLD FRONT MOVES EAST. THUS POPS
NO HIGHER THAN CHC NEEDED AT THIS POINT. BEHIND THE FRONT IT LOOKS
FAIRLY DRY FROM THURSDAY THROUGH SUNDAY AS HIGH PRESSURE PROVES
DOMINANT. TEMPERATURES WILL START OFF ABOVE NORMAL AT THE
BEGINNING OF THE PERIOD THEN TREND TOWARD NORMAL OR EVEN BELOW BY
THE END OF THE WEEK.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
SCATTERED RAIN SHOWERS...ALONG WITH A FEW WEAK THUNDERSTORMS...ARE
POSSIBLE ACROSS THE CWA THIS EVENING AND INTO THE OVERNIGHT HOURS.
BETTER CHANCES WILL BE ACROSS THE WEST...SO WILL STICK WITH A VCSH
MENTION AT KPIR AND KMBG. DUE TO A LACK OF INSTABILITY...EXPECT
THE PRECIPITATION TO COME TO AN END BY MORNING...WITH VFR
CONDITIONS THEN PREVAILING THROUGH THE REMAINDER OF THE TAF
PERIOD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...PARKIN
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
629 PM CDT SUN AUG 31 2014
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
POTENT SHORTWAVE EVIDENT ON WATER VAPOR OVER WYOMING. AHEAD OF
THIS WAVE...OMEGA AND UPPER JET MAX HELPING TO MAINTAIN BAND OF
RAINFALL THAT HAS TREKKED FROM SOUTH CENTRAL SD TO NORTHEAST SD
OVER THE PAST SEVERAL HOURS. HAVE BEEN ADJUSTING POPS FOR THIS
BAND OF RAIN AS IT APPEARS IT WILL SURVIVE MOST IF NOT ALL THE WAY
ACROSS THE CWA. HRRR PICKING UP ON THIS QUITE NICELY.
OVERNIGHT...EXPECTING SCATTERED SHOWERS AND STORMS TO MOVE EAST
ACROSS THE STATE BUT WITH MINIMAL SEVERE THREAT DUE TO LACK OF
INSTABILITY. ONLY QUESTION IS THE DEGREE OF AREAL COVERAGE OF
PRECIP. SOME MODELS GREATER THAN OTHERS...WITH THE HRRR
PARTICULARLY DRY AND SORT OF THE OUTLIER. MOST OTHER MODELS HAVE
ACTIVITY MOVING ACROSS AT LEAST THE SOUTHERN HALF OF SD TONIGHT.
HAVE ADJUSTED POPS ACCORDINGLY AND LINGERED THEM A BIT LONGER
THROUGH THE NIGHT AS NSSL WRF STILL SHOWS CONVECTIVE CLUSTERS OVER
SOUTHEAST SD AT 09Z TONIGHT.
A WEAKER WAVE MOVES ACROSS THE AREA MONDAY...BUT SHOULD STILL
PROVIDE FOR A FEW SCATTERED SHOWERS OR STORMS. AREAL COVERAGE DOES
NOT APPEAR IT WILL QUITE MATCH UP TO WHATS MOVING INTO WESTERN SD
RIGHT NOW...BUT WORTHY OF 20/30 POPS NONETHELESS. AGAIN A LACK OF
INSTABILITY TOMORROW SO SEVERE THREAT IS VERY LOW.
TUESDAY STILL LOOKS DRY WITH NO NOTABLE SYSTEMS IN THE AREA. 500
MB HEIGHTS RISE SLOWLY THROUGH THE DAY WITH WARM AIR ADVECTION
DEVELOPING. HIGHS WILL BUMP UP INTO THE UPPER 70S TO LOW 80S FOR
MOST AREAS.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
THE EARLY PART OF THE PERIOD STARTS OFF SOMEWHAT ACTIVE AS FAIRLY
STRONG SYSTEM MOVES ACROSS THE NORTHERN PLAINS. LATEST MODELS ARE
IN FAIR AGREEMENT ON AVAILABLE MOISTURE/INSTABILITY BUT DO SUGGEST
CAPPING MIGHT FORCE MOST ACTIVITY TO REMAIN NORTH OF THE CWA
WEDNESDAY NIGHT INTO THURSDAY AS COLD FRONT MOVES EAST. THUS POPS
NO HIGHER THAN CHC NEEDED AT THIS POINT. BEHIND THE FRONT IT LOOKS
FAIRLY DRY FROM THURSDAY THROUGH SUNDAY AS HIGH PRESSURE PROVES
DOMINANT. TEMPERATURES WILL START OFF ABOVE NORMAL AT THE
BEGINNING OF THE PERIOD THEN TREND TOWARD NORMAL OR EVEN BELOW BY
THE END OF THE WEEK.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
SCATTERED RAIN SHOWERS...ALONG WITH A FEW WEAK THUNDERSTORMS...ARE
POSSIBLE ACROSS THE CWA THIS EVENING AND INTO THE OVERNIGHT HOURS.
BETTER CHANCES WILL BE ACROSS THE WEST...SO WILL STICK WITH A VCSH
MENTION AT KPIR AND KMBG. DUE TO A LACK OF INSTABILITY...EXPECT
THE PRECIPITATION TO COME TO AN END BY MORNING...WITH VFR
CONDITIONS THEN PREVAILING THROUGH THE REMAINDER OF THE TAF
PERIOD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
648 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 437 AM CDT SAT AUG 30 2014
ISOLATED SHOWERS AHEAD OF WEAK NORTHERN STREAM WAVE IN WEST CENTRAL
MN HAVE COME TO AN END ACROSS SW MN EARLY THIS MORNING...AND NOW
WATCHING MASS OF STRATUS SPILLING SOUTHWARD ACROSS THE NORTHERN
PLAINS. THROUGH AT LEAST MIDDAY...THIS STRATUS SHOULD BE QUITE
PERSISTENT OVER MUCH OF THE CWA...ERODING IN THE VICINITY OF THE LOW
LEVEL RIDGE AXIS NEAR THE JAMES VALLEY. CLOUDS MAY BE SOMEWHAT MORE
PERSISTENT EAST...STYMIED BY FAIRLY WEAK FLOW TOWARD I29 AND
SOUTHWEST MINNESOTA...BUT SHOULD SEE A BETTER DECREASING TREND BY
AFTERNOON. THIS WILL IMPACT POTENTIAL HIGHS TODAY...WHICH WILL
LIKELY RANGE FROM MID TO UPPER 70S EAST...TO MID 80S WEST.
HEADING THROUGH THE NIGHT...ENERGY ACROSS THE PACIFIC NORTHWEST WILL
BEGIN TO NUDGE OUT INTO THE NORTHERN PLAINS. FALLING PRESSURES TO
THE WEST WILL INCREASE SOUTHERLY WIND FLOW...ESPECIALLY OFF SURFACE
AS A 40 TO 50 KNOT LOW LEVEL JET DEVELOPS BY LATE EVENING...VEERING
TOWARD THE FSD CWA BY THE FINAL HALF OF THE NIGHT. AIR AT THIS LEVEL
REMAINS FAIRLY DRY...WITH MOISTURE SOURCE COMING MORE ALOFT NEAR OR
ABOVE 700 HPA. ALL PRECIP TONIGHT IS DEPENDENT ON HIGH BASED SHOWERS
AND THUNDERSTORMS DEVELOPING IN WARM AIR ADVECTION ON NOSE OF
STRONGER ELEVATED MIXED LAYER ACTUALLY BEING SIGNIFICANT ENOUGH TO
BREAK THROUGH THE DRIER LAYER BELOW. AS INITIAL PV LOBE LIFTS OUT
ACROSS THE AREA AFTER 06Z...COULD SEE AT LEAST A LOWER COVERAGE OF
PRECIPITATION...BUT CERTAINLY DOES NOT WARRANT MORE THAN A LOW
CHANCE AT THIS POINT WITH THE DEGREE OF DRY AIR AT LOWER
LEVELS...AND WITH BETTER CONVERGENCE OF THE LOW LEVEL JET TO THE
NORTH. SHADED THE HIGHEST CHANCE BY LATER TONIGHT ACROSS THE HIGHWAY
14 CORRIDOR.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 437 AM CDT SAT AUG 30 2014
FOCUS OF THIS FORECAST IS CERTAINLY ON THUNDERSTORM POTENTIAL AND
ASSOCIATED SEVERE WEATHER RISK SUNDAY...DURING THE MIDDLE OF THE
HOLIDAY WEEKEND. NAM SEEMED TO BE AN OUTLIER IN PATTERN TIMING
AND/OR LOCATION, SO HAVE LARGELY FAVORED A GFS/ECMWF BLEND. WITH
THIS...ANTICIPATE ANY EARLY MORNING ELEVATED CONVECTION TO LIFT
NORTH OF THE AREA/DIMINISH THROUGH MID MORNING...WITH PRIMARY
FOCUS THEN SHIFTING TO SOUTHEAST PORTIONS OF THE CWA AS ONE OF
MANY WAVES SLIDES THROUGH THE MID LEVEL TROUGH MOVING INTO THE
NORTHERN PLAINS. LOCATION OF LOW LEVEL BOUNDARIES MAY BE IMPACTED
BY ANY MORNING CONVECTION...BUT ON BROAD SCALE SHOULD SEE COLD
FRONT INTO WESTERN CWA BY MIDDAY...WITH WARM FRONT LOCATION A
LITTLE MORE UNCERTAIN. PREFERRED MODELS POINT TO STRONGEST LOW
LEVEL WARM ADVECTION ALONG 850MB WARM FRONT EXTENDING INTO EASTERN
NEBRASKA AT MIDDAY...THEN LIFTING NORTHWARD INTO NORTHWEST IOWA
WITH THE MID LEVEL WAVE BY LATE AFTERNOON/EVENING. THIS WAVE
ACCOMPANIED BY STRONG DEEP LAYER SHEAR OF 40+KT AND MUCAPE VALUES
IN EXCESS OF 2500J/KG. FORECAST SOUNDINGS SHOW A WEAKENING BUT
STILL EXISTENT CAPPING INVERSION ABOVE 850MB AT KSUX AND OTHER
POINTS IN OUR CWA AT 21Z...BUT THE APPROACHING WAVE SHOULD HELP
OVERCOME THIS...WITH THE CAP ALLOWING FOR MORE DISCRETE INITIAL
CELL DEVELOPMENT IN THE LATE AFTERNOON TO EARLY EVENING. THIS
SHOULD BE TIME OF GREATEST SEVERE POTENTIAL... WITH LARGE
HAIL...DAMAGING WINDS AND ISOLATED TORNADOS ALL POSSIBLE.
THEREAFTER SYSTEM SHOULD CONGEAL INTO PROGRESSIVE CLUSTER OF STORMS
THROUGH THE EVENING...WHICH THEN SHIFTS EAST OF OUR FORECAST AREA BY
EARLY MONDAY MORNING. DUE TO EXPECTED PROGRESSIVENESS OF SYSTEM...DO
NOT ANTICIPATE WIDESPREAD FLOODING THREAT FROM TRAINING STORMS...BUT
ISOLATED MAINLY URBAN FLASH FLOODING POSSIBLE WITH DEEP MOISTURE
PROVIDING POTENTIALLY HEAVY RAINFALL RATES.
LABOR DAY SHOULD BE QUIET AND COOLER WITH HIGHS BACK INTO THE 70S.
ECMWF/GEM BOTH SHOWING ANOTHER WEAK WAVE TRACKING THROUGH THE REGION
AND BRINGING A CHANCE OF STORMS TO THE AREA MONDAY NIGHT.
LONGER RANGE TUESDAY THROUGH FRIDAY LOOKS TO START OFF AS A FAIRLY
QUIET PERIOD...WITH COOLER HIGHS IN THE 70S TUESDAY WARMING BACK
INTO THE 80S WEDNESDAY/THURSDAY. FAIR CONSENSUS BETWEEN THE GFS AND
ECMWF SHOWING AN INCREASED PRECIP POTENTIAL BY THE END OF THE WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 647 AM CDT SAT AUG 30 2014
IFR TO LIFR CEILINGS WITH STRATUS ENCOMPASSING TAF SITES EARLY
THIS MORNING...AS WELL AS AREAS OF IFR TO MVFR VISIBILITY MAINLY
ACROSS SOUTHWEST MINNESOTA AND NORTHWEST IOWA. WEAKENING LOW LEVEL
FLOW WILL MAKE DECREASE IN STRATUS SOMEWHAT A DIFFICULT PROSPECT...
AND HAVE GONE A BIT SLOWER DECREASE THAN SLOWEST MODEL FOR KFSD...AND
CLOSER TO SLOWER RAP FOR KHON AND KSUX NEARER THE EDGE OF THE FIELD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN
LONG TERM...JH
AVIATION...CHAPMAN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
842 PM CDT SUN AUG 31 2014
.UPDATE...
AT 830 PM...RADAR RETURNS WERE MOST DEFINITELY ON A DOWNWARD
TREND. SOME SLOW MOVING CELLS DROPPED HEALTHY AMOUNTS OF RAINFALL
OVER SE WILSON COUNTY ENOUGH TO WARRANT A FLOOD ADVISORY. DID
RECEIVE A CALL MENTIONING LOW LYING AREAS BECOMING INUNDATED IN
THAT AREA. HOWEVER...COVERAGE HAS DIMINISHED AND THE MID AND UPPER
LEVEL DYNAMICS HAVE MOVED OFF EAST OF THE PLATEAU. AS A
RESULT...LOWERED POP CHANCES ACROSS THE AREA UP UNTIL MIDNIGHT AND
REMOVED SLGT CHC POPS AFTER MIDNIGHT.
IR SATELLITE AND RUC FORECAST SOUNDINGS SHOW MID LEVEL DRYING OVER
THE REST OF THE EVENING AND OVERNIGHT...LIKELY RESULTING IN MOSTLY
CLEAR SKIES AT LEAST FOR A BIT BEFORE SOME BOUNDARY LAYER MOISTURE
ADVECTS NORTHWARD OUT OF NORTHERN ALABAMA DURING THE OVERNIGHT
PERIOD. SINCE SFC MOISTURE WILL STAY IN THE UPPER 60S AND LOW 70S
AND LOW LEVEL FLOW WILL STAY SOUTHWESTERLY...LEFT PATCHY FOG
MENTION IN THE GRIDS THROUGH THE FIRST PART OF THE MORNING. BUT
WITH DECENT WIND FIELDS IN THE BOUNDARY LAYER AND AT LEAST SOME
CLOUD COVER EXPECTED TOWARDS DAYBREAK...DID NOT SEE REASON TO
INCREASE THE FOG COVERAGE TO AREAS OR DENSE WORDING.
&&
.PREV DISCUSSION... /ISSUED 622 PM CDT SUN AUG 31 2014/
UPDATE...FOR 00Z AVIATION.
AVIATION...00Z TAF DISCUSSION.
SHOWERS AND A FEW THUNDERSTORMS CONTINUE TO STREAM ACROSS MIDDLE
TN AT ISSUANCE. DON`T EXPECT TS TO AFFECT KCSV...MAYBE JUST SOME
LIGHT SHOWERS AND IT SHOULD REMAIN VFR. CLOUDS ARE STARTING TO
CLEAR OUT IN THE NORTHWEST...WHICH HAS ALREADY BEEN SEEN AT
KCKV...AND KBNA SHOULD SEE SOME CLEARING OVER THE NEXT FEW HOURS.
I WOULDN`T BE SURPRISED FOR THIS CLEARING TO BE SEEN AT KCSV BY
05-06Z...BUT IT MAY BE SHORT LIVED FOR ALL 3 SITES AS MVFR TO IFR
CIGS WILL LIKELY STREAM INTO THE STATE FROM THE SOUTH STARTING
AROUND 08Z. I DON`T SEE ANY REDUCED VISIBILITIES BECAUSE OF
20-25 KT BOUNDARY LAYER WINDS...BUT CIGS WILL BE ENOUGH TO REDUCE
FLIGHT CATEGORIES FOR SEVERAL HOURS IN THE MORNING.
VFR SHOULD RETURN BY 16Z FOR ALL TERMINALS BUT WINDS WILL PICK UP
AND BE BREEZY ON MONDAY. SW GUSTS OF 16-20 KTS ARE LIKELY DURING
THE AFTERNOON BEFORE RELAXING BY SUNSET.
UNGER
PREV DISCUSSION... /ISSUED 155 PM CDT SUN AUG 31 2014/
DISCUSSION...
CLOUDS HAVE HELD SURFACE INSTABILITY DOWN TODAY SO WE ARE SEEING
FEWER THUNDERSTORMS AS A RESULT BUT SHOWERS HAVE CONTINUED SCATTERED
THROUGHOUT THE REGION AS MOISTURE PLUME CONTINUES TO FEED INTO OUR
AREA WHILE UPPER TROUGH TO THE WEST BEGINS TO SHOW SIGNS OF RELAXING.
WILL KEEPS POPS GOING THROUGH THE EVENING WITH FOG DEVELOPING ALL
AREAS AFTER MIDNIGHT WITH RAIN CHANCES CONTINUING ALONG PLATEAU.
HAVE TRIMMED BACK POPS FOR LABOR DAY BUT CANT RULE ISOLATED THUNDERSTORM
DEVELOPMENT TAKING PLACE IN THE HEAT OF THE DAY WITH PLATEAU AND
EASTERN MIDDLE TENNESSEE FAVORED WHERE MOISTURE WILL BE A LITTLE
DEEPER. BROAD UPPER RIDGE BUILDS ACROSS THE AREA TUESDAY THROUGH
THE REMAINDER OF THE WORK WEEK SENDING WESTERLIES INTO THE NORTHERN
U.S. NEAR CANADIAN BORDER LATTER PART OF WEEK. IN SPITE OF UPPER
RIDGING MODELS DRIVE A SERIES OF SURFACE FRONTS INTO THE MID STATE
ONE ON TUESDAY/WEDNESDAY AND ANOTHER ON THURSDAY/FRIDAY AND YET
ANOTHER OVER THE WEEKEND. SO HAVE KEPT POPS RUNNING THROUGH PRETTY
MUCH THE ENTIRE WORK WEEK AND INTO THE UPCOMING WEEKEND.
TEMPS WILL HEAT BACK UP THIS WEEK WELL ABOVE CLIMATOLOGY. BY SUNDAY
TEMPS SHOULD BE CLOSER TO SEASONAL NORMALS AS 1020 MBAR CANADIAN
HIGH SETS TO OUR NORTH OVER GREAT LAKES REGION.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
TB12
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
249 PM EDT SAT AUG 30 2014
.SHORT TERM...(TONIGHT THROUGH MONDAY)...GULF MOISTURE CONTINUES TO
STREAM NORTHWARD FROM THE WESTERN GULF OF MEXICO THIS AFTERNOON.
AIR MASS IS BECOMING SLIGHTLY TO MODERATELY UNSTABLE WITH SPOTTY
CONVECTION POPPING OVER SE TN...AND MORE SO TO OUR SW OVER NE AL.
I ADJUSTED THE SHORT TERM GRIDS FOR LATE AFTERNOON AND THIS EVENING
IN LINE WITH THE SIMILAR HRRR AND RAP MODELS...WHICH SUPPORTS
LIKELY POPS OVER WRN AREAS. THE SHORTWAVE TROUGH MOVES EAST ACROSS
THE WRN GREAT LAKES AND OHIO VALLEY REGION OVERNIGHT...WHICH SHOULD
KEEP HIGHER POPS IN ORDER AFTER MIDNIGHT ACROSS OUR NRN PLATEAU AND
EXTREME WRN SW VA COUNTIES.
FOR SUNDAY...STAYED WITH OUR LOW END OF LIKELY POPS...WHICH ARE
HIGHER THAN 12Z MOS GUIDANCE...SINCE THE SRN END OF THE UPPER
TROUGH WILL BE PASSING EAST ACROSS THE TN VALLEY AND SRN
APPALACHIANS DURING PEAK HEATING. LOWERED POPS FROM THE WEST
SUNDAY NIGHT WITH PASSAGE OF THE TROUGH AXIS. MONDAY ALSO SHAPING
UP DRIER THAN PREVIOUS GRIDS...SO CUT POPS BACK TO 20 TO 30
PERCENT...AND PUSHED MAX TEMPS BACK UP TO THE SIMILAR UPR 80S TO
LWR 90S FROM 12Z MOS. OTHERWISE...12Z NAM AND GFS MOS TEMPS WERE IN
GENERAL AGREEMENT AND CLOSELY FOLLOWED.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)...NOT MUCH FOCUS FOR
CONVECTION THROUGHOUT THE LONG TERM PERIOD OTHER THAN INTENSE SOLAR
HEATING AND OROGRAPHIC LIFT ON THE MAJOR TERRAIN FEATURES.
HOWEVER...THERE WILL BE SOME WEAK SHORT WAVE ENERGY MAKING ITS WAY
ACROSS THE NORTHEASTERN QUARTER OF THE NATION LATER TUESDAY INTO
WEDNESDAY AND THIS CONFIGURATION MAY COAX A WEAK COOL FRONT INTO THE
SOUTHERN APPALACHIAN REGION WEDNESDAY THROUGH FRIDAY. THIS BOUNDARY
MAY ALLOW FOR A SLIGHT INCREASE IN PROBABILITY OF PRECIPITATION
MAINLY ON WEDNESDAY IF IT CAN MAKE IT FAR ENOUGH SOUTH. OTHERWISE
GENERALLY KEPT POPS AROUND 20-25 PERCENT AS UPPER RIDGING HANGS
AROUND THE SOUTHEASTERN U.S. TRENDED MAX TEMPS A LITTLE CLOSER TO
SUGGESTED HIGHS FOR THE UPCOMING WEEK AS THE ANNUAL LATE SUMMER LAG
IN HEATING DUE TO LONG WAVE RE-RADIATION FINALLY CATCHES UP TO US.
STAYED PRETTY CLOSE TO MINS THROUGH THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 71 87 71 93 / 60 60 40 20
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 86 70 91 / 50 60 30 20
OAK RIDGE, TN 70 84 69 91 / 60 60 40 20
TRI CITIES AIRPORT, TN 66 87 65 87 / 50 60 40 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
945 AM EDT SAT AUG 30 2014
.DISCUSSION...PLUME OF MOISTURE STREAMING NORTH FROM THE GULF COAST
REGION THIS MORNING. PRECIPITABLE WATER VALUES CONTINUE TO RISE ON
BOTH OHX AND RNK 12Z SOUNDINGS. EXPECT LIFT TO DEVELOP AHEAD OF THE
APPROACHING UPPER TROUGH THIS AFTERNOON. THE HRRR AND RAP MODELS
SPREAD SHOWERS AND TSRA INTO OUR PLATEAU AND SE TN COUNTIES LATE
THIS AFTERNOON...SO MAY NEED TO GO WITH LIKELY POPS FOR THOSE AREAS.
OTHERWISE...FORECAST GRIDS AND PRODUCTS LOOK ON TRACK.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 89 71 87 71 / 50 50 60 40
KNOXVILLE MCGHEE TYSON AIRPORT, TN 88 71 86 69 / 40 50 60 30
OAK RIDGE, TN 88 71 84 69 / 40 50 60 40
TRI CITIES AIRPORT, TN 89 67 85 65 / 30 50 60 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
435 AM CDT SAT AUG 30 2014
.DISCUSSION...
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH OVER THE
UPPER MIDWEST MOVING TOWARDS THE GREAT LAKES WITH ANOTHER TROUGH
PUSHING ACROSS THE PAC NW. TROUGH AXIS STRETCHES FROM THE MIDWEST
INTO TX WITH A WEAK SHORT WAVE TROUGH OVER S TX. WATER VAPOR
IMAGERY SHOWS DRIER AIR ON THE BACK SIDE OF THIS SHORTWAVE WITH
MOIST AIR AND ASCENT TO THE EAST OVER SE TX. SHOWERS AND
THUNDERSTORMS HAVE CONTINUED TO DEVELOP ALONG THE COAST AND IN THE
OFFSHORE WATERS OF THE NW GULF IN RESPONSE TO THE LIFT. THERE IS
STILL PLENTY OF TROPICAL MOISTURE LINGERING OVER THE AREA TO
SUPPORT HIGH RAIN RATES AND LOCALLY HEAVY RAINFALL. HIGHER RAIN
CHANCES REMAIN IN THE FORECAST ALONG THE COAST BUT NOT QUITE AS
MUCH AS BEFORE. POPS OF 60/70 PERCENT LOOK REASONABLE ESPECIALLY
SINCE THE MAIN MOISTURE AXIS HAS SHIFTED MOVER OVER SW LA AS
GFS/ECMWF HAVE BEEN SUGGESTING. EVEN HI RES WRF AND HRRR FORECASTS
SHOW MOST OF THE CONVECTION ALONG THE COAST AND ACROSS E TX INTO
SW LA. WILL KEEP 60 POPS IN THE FORECAST FOR MUCH OF THE AREA THIS
AFTERNOON AS WIDESPREAD CONVECTION COULD STILL DEVELOP WITHIN
MOIST UNSTABLE AIRMASS DUE TO DAY TIME HEATING. THERE WILL STILL
BE A DECENT GRADIENT BETWEEN HIGH RAIN CHANCES AND LOW RAIN
CHANCES. DEEP MOISTURE WILL STILL SUPPORT RAIN RATES OF EASILY 1
TO 2 INCHES OF RAIN AN HOUR. STORMS SHOULD BE MOVING AT A
REASONABLE SPEED SO ANY FLOOD THREAT WILL BE VERY LOCALIZED.
UPPER LEVEL TROUGH AXIS SHEARS OUT OVER THE AREA WITH UPPER LEVEL
RIDGING BEGINNING TO TAKE SHAPE OVER MUCH OF THE SOUTHERN U.S.
MODELS STILL KEEP DEEP MOISTURE IN PLACE WHICH COULD STILL SUPPORT
SCT THUNDERSTORM ACTIVITY DURING THE DAY SUNDAY WITH DAYTIME
HEATING. FORECAST WILL KEEP 40/50 POPS ALONG THE MAIN MOISTURE
AXIS. AGAIN LOCALLY HEAVY RAINFALL WILL BE POSSIBLE.
MON/TUE THE UPPER LEVEL RIDGE BECOMES MORE ESTABLISHED OVER TX AS
POTENT SHORTWAVE OVER PAC NW MOVES ACROSS THE N PLAINS. TROPICAL
DISTURBANCE IN W CARIBBEAN WILL MOVE TOWARDS THE YUCATAN OVER THE
WEEKEND AND INTO THE GULF MON/TUE. THE RIDGE SHOULD HELP STEER
THIS TROPICAL WAVE TOWARDS THE MEXICAN COAST TUE INTO WED. MAIN
IMPACT FOR THE TX COAST MAY BE ANOTHER INCREASE IN TROPICAL
MOISTURE. FORECAST WILL CONTINUE WITH MAINLY 20/30 POPS FOR THE
MIDDLE OF THE COMING WEEK THROUGH THE END OF THE WEEK. MAX TEMPS
WILL GRADUALLY INCREASE BACK INTO THE MID 90S FOR MOST AREAS AS
THE RIDGE INCREASES.
&&
.MARINE...
LIGHT TO MODERATE ONSHORE WINDS SHOULD WEAKEN SLIGHTLY TODAY
BEFORE PICKING UP AGAIN THIS EVENING. A SCEC MAY BE NEEDED
OVERNIGHT INTO SUNDAY MORNING AS THE PRESSURE GRADIENT TIGHTENS
ACROSS THE REGION. SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE ACROSS THE COASTAL WATERS OVER THE WEEKEND AS AN UPPER
LEVEL DISTURBANCE MOVES ACROSS THE REGION. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 93 74 94 76 95 / 30 20 30 10 20
HOUSTON (IAH) 90 76 92 77 93 / 60 50 50 10 30
GALVESTON (GLS) 87 80 89 81 90 / 60 50 50 10 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
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
752 PM EDT SUN AUG 31 2014
.SYNOPSIS...
THE REGION WILL STAY BETWEEN A LARGE HIGH PRESSURE SYSTEM OVER
THE SOUTHEAST UNITED STATES AND A COMPLEX LOW PRESSURE SYSTEM
CROSSING THE GREAT LAKES. DISTURBANCES PASSING BETWEEN THESE TWO
FEATURES WILL COMBINE WITH HEAT AND HUMIDITY TO RESULT IN
PERIODIC CHANCES OF SHOWERS AND STORMS INTO EARLY WEEK. A COLD
FRONT FINALLY ARRIVES FROM THE NORTH WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 720 PM EDT SUNDAY...
LOOKING AT WEAKENING CONVECTION THIS EVENING OVER THE EAST AND
WEST. ANOTHER DISTURBANCE THAT IS OVER THE CUMBERLAND PLATEAU
THIS EVENING IS EXPECTED TO SHIFT NE INTO THE CENTRAL APPALACHIANS
AND BLUE RIDGE BY MIDNIGHT. STORMS OVER KNOXVILLE HAVE SHOWN A
WEAKENING TREND AS HAD THE SHOWERS IN ERN KY/WRN WV. STILL THINK
THERE MAY BE SOME MEASURABLE RAINFALL IN THE FAR WEST LATE THIS
EVENING SO WILL KEEP HIGHER POPS THERE...BUT LOWER POPS TO SLIGHT
CHANCE EAST OF THE WV/VA BORDER.
PREVIOUS VALID DISCUSSION...
SHORTWAVES WILL BE EXITING BY EARLY MONDAY LEAVING THE REGION IN DECENT
WEST/SW FLOW ALOFT BUT WITHOUT MUCH FORCING WELL IN ADVANCE OF THE NEXT
UPSTREAM 5H TROF/COLD FRONT TO THE NW. FORECAST SOUNDINGS SHOW QUITE A
DEEP WESTERLY FLOW WHICH RESULTS IN DRYING ALOFT/LOWERING PWATS ESPCLY
WEST MONDAY AFTERNOON AND A LEE TROUGH ACROSS THE PIEDMONT. MOST
GUIDANCE SOLUTIONS SHOW A LACK OF MUCH CONVECTION IN THIS REGIME WITH
ANY FOCUS PROVIDED BY OROGRAPHICS DUE TO WESTERLY CONVERGENCE AND
PERHAPS LATE DAY LOW LEVEL BACKING SE. THUS WILL LEAVE IN SOME LOW POPS
MAINLY WEST AS APPEARS A SUBTLE WAVE ALOFT COULD SNEAK THROUGH AROUND
THE TIME OF MAX HEATING. OTRW EXPECT WEAK LAPSES...LACK OF DEEP
INSTABILITY AND EASTERN DOWNSLOPE TO LIMIT OVERALL COVERAGE WITH MUCH
OF THE DAY LIKELY DRY AFTER EARLY MID DECK/FOG ERODE.
COULD BE ONE OF THE WARMEST DAYS SEEN IN A WHILE WITH 85H TEMPS PUSHING
+21C OVER DECENT DOWNSLOPE AND UNDER AMPLE AFTERNOON SUN. THIS WOULD
SUPPORT SOME MID 90S PIEDMONT...WITH UPPER 80S/LOW 90S BLUE RIDGE...
AND LOW/MID 80S WESTERN ELEVATIONS IF CAN GET A TEMP JUMP AFTER A WARM
START IN THE MORNING.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM EDT SUNDAY...
WITH WEAK HIGH PRESSURE BUILDING IN FROM THE SOUTH...EXPECT TO HEAD
INTO LATE MONDAY NIGHT WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. AS
SUCH...WOULD NOT BE SURPRISED TO SEE PATCHY FOG DEVELOP IN SOME OF
THE MOUNTAIN VALLEYS EARLY MORNING...WHICH WILL BURN OFF QUICKLY
SHORTLY AFTER 9 AM.
DURING TUESDAY AFTERNOON...SHOWER AND THUNDERSTORM ACTIVITY WILL
INCREASE AS AN UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT APPROACH
FROM THE WEST. ACTIVITY WILL START OFF ACROSS THE MOUNTAINS...SPOTTY
AT FIRST DUE TO THE WESTERLY DOWNSLOPE FLOW...AND THEN WILL SPREAD
EAST ACROSS THE PIEDMONT DURING THE EVENING AS THE UPPER LEVEL
ENERGY SHIFTS EAST. LIGHT WINDS AND WARM TEMPERATURES ALOFT WILL
LIMIT INSTABILITY...AND BELIEVE STRONG THUNDERSTORMS WILL BE
ISOLATED AND SHORT LIVED. SHOWER AND THUNDERSTORM ACTIVITY WILL THEN
DIMINISH THROUGH THE NIGHT WITH THE LOSS OF HEATING.
BY WEDNESDAY MORNING...WILL HAVE A WEAK BOUNDARY SITUATED ACROSS OUR
AREA...WHICH WILL EXHIBIT LITTLE MORE THAN A SHIFT IN WIND DIRECTION
FROM ONE SIDE TO THE OTHER AS THE TRULY COOLER AND DRIER AIR WILL
REMAIN WELL NORTH OF OUR AREA. REGARDLESS...THE LOW LEVEL
CONVERGENCE ALONG THE BOUNDARY WILL BE ENOUGH TO TRIGGER ANOTHER
ROUND OF SPOTTY SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND
EVENING. BETTER CHANCES FOR RAINFALL WILL BE FOUND SOUTH OF HIGHWAY
460.
TEMPERATURES HEADING INTO THE MIDDLE OF THE WEEK WILL BE WARMER THAN
NORMAL THANKS TO UPPER LEVEL RIDGING ACROSS THE SOUTHEAST STATES.
LOOK FOR HIGHS TO RANGE FROM THE LOW/MID 80S ACROSS THE MOUNTAINS...
TO THE LOW/MID 90S ACROSS THE SOUTHSIDE. OVERNIGHT LOWS WILL RANGE
FROM THE MID 60S WEST TO THE LOW 70S EAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 345 PM SUNDAY...
A WEAK BOUNDARY WILL REMAIN SITUATED ACROSS THE AREA ON
THURSDAY... PROVIDING THE LOW LEVEL FOCUS FOR SHOWERS AND
THUNDERSTORMS... MAINLY SOUTH OF HIGHWAY 460. ACTIVITY IS EXPECTED
TO REMAIN WIDELY SCATTERED DUE TO THE UPPER LEVEL RIDGE ACROSS THE
SOUTHEAST STATES BUILDING NORTH...HELPING TO LIMIT INSTABILITY.
HIGH PRESSURE WILL PASS ACROSS NEW ENGLAND...ALLOWING WINDS TO
SHIFT EASTERLY THROUGH THE DAY...AND THEN SOUTHEASTERLY DURING THE
EVENING.
AN APPROACHING UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT WILL
TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION ON
FRIDAY AND SATURDAY. THE COLD FRONT WILL MOVE ACROSS OUR AREA
SATURDAY NIGHT...USHERING IN COOLER AND DRIER CANADIAN HIGH
PRESSURE.
TROPICAL AIR WILL REMAIN ACROSS THE AREA THROUGH THE END OF THE
WEEK. AS SUCH...EXPECT WARM AND MUGGY CONDITIONS...WITH
TEMPERATURES HOLDING SLIGHTLY ABOVE NORMAL. COOLER TEMPERATURES
WILL ARRIVE WITH THE COLD FRONT AT THE END OF THE WEEK.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 725 PM EDT SUNDAY...
NOT REALLY EXPECTING MUCH IN THE WAY OF SHOWERS AT TAF SITES
EXCEPT LWB. HRRR IS CATCHING ONTO SHOWERS FROM FAR SW VA INTO ERN
KY/WV MOVING NE TO LWB BY 0130Z. SHOULD SEE A SMALL PERIOD OF
SHOWERS HERE...COULD REDUCE VSBY TO 5SM.
OTHERWISE...OVERNIGHT THE OVERALL THREAT OF SHOWERS WILL FADE WITH
A SCT/BKN MID DECK LINGERING. FOG CHANCES ARE GOOD BUT THE MID
DECK SHOULD LIMIT HOW FAR DOWN VSBYS DROP. WILL KEEP MOST TAF
SITES NO WORSE THAN MVFR OVERNIGHT WITH LWB DROPPING OCCASIONALLY
TO IFR AFTER 10Z.
LAST MID LEVEL WAVE WILL PASS TO THE NW BY EARLY MONDAY LEAVING
THE AREA IN BETWEEN THIS FEATURE AND THE NEXT UPSTREAM COLD FRONT.
DEEP WESTERLY FLOW COMBINED WITH LACK OF FOCUS AND DECENT MIXING
SHOULD INHIBIT MUCH CONVECTION DURING MONDAY ESPCLY IF EARLY MID
DECK PERSISTS. THIS SUPPORTS GOOD FLYING CONDITIONS FOR MUCH OF
MONDAY AFTER EARLY LOW CLOUDS/FOG FADE WITH ONLY ISOLATED
CONVECTION LIKELY.
EXTENDED DISCUSSION...
UPPER TROUGH AND ITS ASSOCIATED COLD FRONT WILL APPROACH FROM THE
NORTHWEST TUESDAY WITH SIMILAR ISOLATED SHOWERS/STORMS EXPECTED
DURING THE DAY AHEAD OF THE BOUNDARY. FRONT SETTLES CLOSER TUESDAY
NIGHT INTO WEDNESDAY...WHEN BETTER COVERAGE OF SHRA/TSRA IS
EXPECTED...AND THEN ACROSS THE SOUTH THURSDAY WHERE THE BOUNDARY
STALLS. HOWEVER LOW CONFIDENCE ON THE TIMING AND SOUTHWARD
POSITION OF THE BOUNDARY AT THIS POINT. THUS APPEARS MAINLY VFR
ON TUESDAY...WITH PERIODS OF MVFR WEDNESDAY-THURSDAY IN MORE
ORGANIZED MAINLY AFTERNOON/EVENING CONVECTION...AND MVFR/IFR UNDER
EARLY MORNING FOG IN THE VALLEYS AND WHERE EARLIER HEAVY RAIN
OCCURRED. FRONT WASHES OUT TO THE SOUTH OF THE AREA FRIDAY WITH
MORE DIURNAL NATURE SHOWERS AND STORMS...OTRW VFR.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/JH
NEAR TERM...JH/WP
SHORT TERM...NF
LONG TERM...NF
AVIATION...AMS/JH/WP
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
735 AM EDT SAT AUG 30 2014
.SYNOPSIS...
A STALLED FRONT TRAILED FROM SOUTH CAROLINA TO ILLINOIS THIS
MORNING. THIS FRONT WILL MOVE NORTH AND DISSIPATE OVER THE MID
ATLANTIC REGION BY SUNDAY. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
THE GREAT LAKES TONIGHT AND SUNDAY WITH A COLD FRONT TRAILING FROM
THE UPPER MISSISSIPPI VALLEY TO THE CENTRAL PLAINS BY SUNDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT SATURDAY...
RADAR SHOWED A NARROW BAND OF SHOWERS FROM ASHE COUNTY NC TO HALIFAX
COUNTY VA. HRRR MOVES THIS PRECIPITATION NORTH THEN HAS IT
DISSIPATING BY 12Z/8AM. IN CONTRAST THE 4KM NAM HAS THE
PRECIPITATION MOVING ALL THE WAY INTO CENTRAL VIRGINIA BY NOON. WILL
LEAN TOWARD THE NAM SOLUTION.
FRONT WAS STATIONARY FROM ILLINOIS TO SOUTH CAROLINA. MODELS TAKE
SURFACE HIGH PRESSURE OFF THE NEW ENGLAND COAST TODAY...ALLOWING THE
BOUNDARY TO MOVE NORTH...BUT EXPECT IT WILL TAKE MUCH OF THE DAY TO
MOVE OUT OF THE COUNTY WARNING AREA. WINDS COMING AROUND TO THE
SOUTH AND ANY CLEARING IN THE AFTERNOON WILL INFLUENCE HOW MUCH
TEMPERATURES WILL RISE TODAY. CLOUD COVER WILL ALSO LIMIT
INSTABILITY TODAY...SO EVEN WITH THE FRONT MOVING THROUGH THE
COVERAGE OF SHOWERS AND THUNDERSTORMS WILL REMAIN ISOLATED TO
SCATTERED. 00Z CANADIAN STARTS BREAKING OUT CLOUD COVER AROUND
14Z/10AM BUT DOES NOT HAVE ALL THE LOW CLOUDS ERODING UNTIL NEARLY
19Z/3PM. WILL STAY CLOSE TO THIS TIMING.
UPPER RIDGE AXIS IS JUST OFF THE SOUTHEAST COAST BY TONIGHT. BROAD
SOUTHWEST FLOW FROM THE LOWER MISSISSIPPI VALLEY TO THE EASTERN GREAT
LAKES TONIGHT. THE SHORT WAVE COMING OUT OF THE NORTHERN GULF AND
THE BEST Q-V FORCING ALONG THE APPROACHING COLD FRONT WILL STILL BE
WEST OF THE FORECAST AREA BY SUNDAY MORNING. MID AND HIGH CLOUDS
WILL COVER THE WESTERN COUNTY WARNING AREA OVERNIGHT...THEN
INCREASING PROBABILITY OF PRECIPITATION IN THE FAR WEST. WITH THE
INCREASING CLOUDS AND SINCE THE FORECAST AREA WILL BE WELL WITHIN
THE WARM SECTOR TONIGHT...NOT MUCH DROP IN TEMPERATURES IS EXPECTED.
USED THE WARMER GUIDANCE FOR OVERNIGHT LOWS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 310 AM EDT SATURDAY...
A STUBBORN UPPER LEVEL RIDGE WILL HUG THE SOUTHEASTERN COAST LONGER
THAN PREVIOUSLY EXPECTED. FROM A MODEL STAND POINT...THIS UPPER
RIDGE IS ALSO FARTHER INLAND...WHICH WILL LOWER THE CHANCE OF
SHOWERS AND THUNDERSTORMS AS THE SHORT WAVE TRACK IS PUSHED
WESTWARD. THE LATEST 00Z MODELS TRACKS A TROPICAL SHORT WAVE ON THE
OUTER RINGS OF THE RIDGE ACROSS EASTERN TENNESSEE AND CENTRAL
KENTUCKY SUNDAY MORNING...THEN OVER THE OHIO VALLEY IN THE
AFTERNOON. AS THIS SHORT WAVE MOVES OVER THE OHIO VALLEY IN THE
AFTERNOON...MID LEVEL CAPPING WEAKENS ALLOWING STORMS TO GENERATE
ALONG OUT FLOW BOUNDARIES AND IN MODEST INSTABILITIES. WITH THE
STRONGEST LOW LEVEL JET REMAINING OVER THE TENNESSEE AND OHIO
VALLEYS...DISORGANIZED PULSE-LIKE STORMS ARE EXPECTED OVER THE
MOUNTAINS IN THE AFTERNOON AND MAY DRIFT EAST OF THE BLUE RIDGE IN
THE EVENING...IF THE RIDGE DOES JOG TO THE SOUTHEAST. THERE WILL
ALSO BE A LEE TROUGH OVER THE PIEDMONT THAT MAY HELP FIRE STORMS
EAST OF THE BLUE RIDGE DURING THE LATE AFTERNOON AND EVENING HOURS.
CAN NOT RULE OUT THE CHANCE FOR A FEW STORMS TO BECOME SEVERE WHERE
THE CAP IS THE WEAKEST...MOUNTAIN EMPIRE TO THE BLUEFIELD RICHLANDS
AREA. SINCE THE MODELS HAVE MOVED ORGANIZED CONVECTION TO THE
WEST...LOWERED POPS ESPECIALLY IN THE EAST. SINCE THE CHANCES OF
SHOWERS IS LOWER AND SCATTERED IN NATURE...INCREASE TEMPERATURES
ACROSS THE MOUNTAINS INTO THE MID 80S AND U80S-L90S EAST OF THE BLUE
RIDGE.
ON MONDAY...MODELS ONCE AGAIN DRIFT UPPER LEVEL RIDGE TO THE
SOUTH...PLACING THE OUTER RINGS ACROSS THE FORECAST AREA. A WEAK
SHORT WAVE IS EXPECTED TO TRACK ALONG THE SOUTHERN APPALACHIANS
BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA MONDAY.
ONCE THIS SHORT WAVES TRACKS NORTH OF THE AREA...POSSIBLY BY EARLY
AFTERNOON...SURFACE HIGH PRESSURE WILL BUILD ACROSS THE REGION
MONDAY NIGHT. WITH THE AREA REMAINING IN A MUGGY AIR MASS...PATCHY
DENSE FOG IS LIKELY FOR MOUNTAIN VALLEYS. IF SHOWERS ARE PRIMARILY
DURING THE MORNING...MONDAY AFTERNOON TEMPERATURES WILL WARM INTO
THE MID 80S IN THE WEST TO U80S-L90S EAST OF THE BLUE RIDGE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 730 AM EDT SATURDAY...
BROAD AREA OF STRATUS HAD SPREAD WEST ACROSS THE REGION. THE
WESTERN EDGE WAS CLOSE TO KLWB AND KBLF...WITH A SMALL WHOLE THAT
JUST CLOSED RIGHT OVER THE KROA AIRPORT. KBLF AND KLWB SHUD
WILL MAINTAIN VFR CLOUDS.
FOR KBCB/KROA/KDAN AND KLYH IMPROVEMENT IN CEILINGS WILL BE SLOW
THIS MORNING AS A WEAK FRONT LIFTS NORTH THROUGH THE AREA. ONLY
MEDIUM CONFIDENCE AS TO WHEN CEILINGS WILL FINALLY GET BACK TO
VFR. THE THREAT OF SHOWERS AND THUNDERSTORMS THROUGH THE TAF
PERIOD REMAINS LOW ENOUGH TO KEEP OUT OF THE FORECAST FOR NOW.
EXPECT CLOUD COVER TO BE TOO EXTENSIVE TONIGHT FOR FOG
FORMATION...ESPECIALLY IN THE MOUNTAINS. MODELS SUGGESTED THAT LOW
CLOUDS...WITH IFR CEILINGS...MAY REFORM IN THE PIEDMONT. THIS
WOULD MOST LIKELY IMPACT KLYH AND KDAN VERY LATE IN THE TAF
FORECAST PERIOD. CONFIDENCE TOO LOW AT THIS TIME TO INCLUDE IN
THE FORECAST.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
ALONG AND NORTH OF A KHSP-KFVX LINE THIS EVENING...JUST SOUTH OF
THE AGAIN STALLED FRONTAL BOUNDARY.
LATE TONIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE WILL
HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW ENGLAND.
ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A
GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS
ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY
INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS
PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE
MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...PC
AVIATION...AMS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
417 AM EDT SAT AUG 30 2014
.SYNOPSIS...
A STALLED FRONT TRAILED FROM SOUTH CAROLINA TO ILLINOIS THIS
MORNING. THIS FRONT WILL MOVE NORTH AND DISSIPATE OVER THE MID
ATLANTIC REGION BY SUNDAY. A LOW PRESSURE SYSTEM WILL MOVE ACROSS
THE GREAT LAKES TONIGHT AND SUNDAY WITH A COLD FRONT TRAILING FROM
THE UPPER MISSISSIPPI VALLEY TO THE CENTRAL PLAINS BY SUNDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT SATURDAY...
RADAR SHOWED A NARROW BAND OF SHOWERS FROM ASHE COUNTY NC TO HALIFAX
COUNTY VA. HRRR MOVES THIS PRECIPITATION NORTH THEN HAS IT
DISSIPATING BY 12Z/8AM. IN CONTRAST THE 4KM NAM HAS THE
PRECIPITATION MOVING ALL THE WAY INTO CENTRAL VIRGINIA BY NOON. WILL
LEAN TOWARD THE NAM SOLUTION.
FRONT WAS STATIONARY FROM ILLINOIS TO SOUTH CAROLINA. MODELS TAKE
SURFACE HIGH PRESSURE OFF THE NEW ENGLAND COAST TODAY...ALLOWING THE
BOUNDARY TO MOVE NORTH...BUT EXPECT IT WILL TAKE MUCH OF THE DAY TO
MOVE OUT OF THE COUNTY WARNING AREA. WINDS COMING AROUND TO THE
SOUTH AND ANY CLEARING IN THE AFTERNOON WILL INFLUENCE HOW MUCH
TEMPERATURES WILL RISE TODAY. CLOUD COVER WILL ALSO LIMIT
INSTABILITY TODAY...SO EVEN WITH THE FRONT MOVING THROUGH THE
COVERAGE OF SHOWERS AND THUNDERSTORMS WILL REMAIN ISOLATED TO
SCATTERED. 00Z CANADIAN STARTS BREAKING OUT CLOUD COVER AROUND
14Z/10AM BUT DOES NOT HAVE ALL THE LOW CLOUDS ERODING UNTIL NEARLY
19Z/3PM. WILL STAY CLOSE TO THIS TIMING.
UPPER RIDGE AXIS IS JUST OFF THE SOUTHEAST COAST BY TONIGHT. BROAD
SOUTHWEST FLOW FROM THE LOWER MISSISSIPPI VALLEY TO THE EASTERN GREAT
LAKES TONIGHT. THE SHORT WAVE COMING OUT OF THE NORTHERN GULF AND
THE BEST Q-V FORCING ALONG THE APPROACHING COLD FRONT WILL STILL BE
WEST OF THE FORECAST AREA BY SUNDAY MORNING. MID AND HIGH CLOUDS
WILL COVER THE WESTERN COUNTY WARNING AREA OVERNIGHT...THEN
INCREASING PROBABILITY OF PRECIPITATION IN THE FAR WEST. WITH THE
INCREASING CLOUDS AND SINCE THE FORECAST AREA WILL BE WELL WITHIN
THE WARM SECTOR TONIGHT...NOT MUCH DROP IN TEMPERATURES IS EXPECTED.
USED THE WARMER GUIDANCE FOR OVERNIGHT LOWS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 310 AM EDT SATURDAY...
A STUBBORN UPPER LEVEL RIDGE WILL HUG THE SOUTHEASTERN COAST LONGER
THAN PREVIOUSLY EXPECTED. FROM A MODEL STAND POINT...THIS UPPER
RIDGE IS ALSO FARTHER INLAND...WHICH WILL LOWER THE CHANCE OF
SHOWERS AND THUNDERSTORMS AS THE SHORT WAVE TRACK IS PUSHED
WESTWARD. THE LATEST 00Z MODELS TRACKS A TROPICAL SHORT WAVE ON THE
OUTER RINGS OF THE RIDGE ACROSS EASTERN TENNESSEE AND CENTRAL
KENTUCKY SUNDAY MORNING...THEN OVER THE OHIO VALLEY IN THE
AFTERNOON. AS THIS SHORT WAVE MOVES OVER THE OHIO VALLEY IN THE
AFTERNOON...MID LEVEL CAPPING WEAKENS ALLOWING STORMS TO GENERATE
ALONG OUT FLOW BOUNDARIES AND IN MODEST INSTABILITIES. WITH THE
STRONGEST LOW LEVEL JET REMAINING OVER THE TENNESSEE AND OHIO
VALLEYS...DISORGANIZED PULSE-LIKE STORMS ARE EXPECTED OVER THE
MOUNTAINS IN THE AFTERNOON AND MAY DRIFT EAST OF THE BLUE RIDGE IN
THE EVENING...IF THE RIDGE DOES JOG TO THE SOUTHEAST. THERE WILL
ALSO BE A LEE TROUGH OVER THE PIEDMONT THAT MAY HELP FIRE STORMS
EAST OF THE BLUE RIDGE DURING THE LATE AFTERNOON AND EVENING HOURS.
CAN NOT RULE OUT THE CHANCE FOR A FEW STORMS TO BECOME SEVERE WHERE
THE CAP IS THE WEAKEST...MOUNTAIN EMPIRE TO THE BLUEFIELD RICHLANDS
AREA. SINCE THE MODELS HAVE MOVED ORGANIZED CONVECTION TO THE
WEST...LOWERED POPS ESPECIALLY IN THE EAST. SINCE THE CHANCES OF
SHOWERS IS LOWER AND SCATTERED IN NATURE...INCREASE TEMPERATURES
ACROSS THE MOUNTAINS INTO THE MID 80S AND U80S-L90S EAST OF THE BLUE
RIDGE.
ON MONDAY...MODELS ONCE AGAIN DRIFT UPPER LEVEL RIDGE TO THE
SOUTH...PLACING THE OUTER RINGS ACROSS THE FORECAST AREA. A WEAK
SHORT WAVE IS EXPECTED TO TRACK ALONG THE SOUTHERN APPALACHIANS
BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA MONDAY.
ONCE THIS SHORT WAVES TRACKS NORTH OF THE AREA...POSSIBLY BY EARLY
AFTERNOON...SURFACE HIGH PRESSURE WILL BUILD ACROSS THE REGION
MONDAY NIGHT. WITH THE AREA REMAINING IN A MUGGY AIR MASS...PATCHY
DENSE FOG IS LIKELY FOR MOUNTAIN VALLEYS. IF SHOWERS ARE PRIMARILY
DURING THE MORNING...MONDAY AFTERNOON TEMPERATURES WILL WARM INTO
THE MID 80S IN THE WEST TO U80S-L90S EAST OF THE BLUE RIDGE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS OF 140 AM EDT FRIDAY...
BROAD AREA OF STRATUS HAD SPREAD WEST ACROSS THE REGION. THE
WESTERN EDGE WAS CLOSE TO KLWB AND KBLF. THESE AIRPORTS MAY GO
BACK AND FORTH BETWEEN SCATTERED VFR CLOUDS AND MVFR CEILINGS
THROUGH 14Z/10AM. FOR KBCB/KROA/KDAN AND KLYH HIGHER CONFIDENCE
THAT CEILINGS WILL LOWER TO MVFR OR IFR.
IMPROVEMENT IN CONDITIONS WILL BE SLOW THIS MORNING AS A FRONT
LIFTS NORTH THROUGH THE AREA. ONLY MEDIUM CONFIDENCE AS TO WHEN
CEILINGS WILL LIFT BACK TO VFR. THE THREAT OF SHOWERS AND
THUNDERSTORMS THROUGH THE TAF PERIOD REMAINS LOW ENOUGH TO KEEP
OUT OF THE FORECAST FOR NOW.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
ALONG AND NORTH OF A KHSP-KFVX LINE THIS EVENING...JUST SOUTH OF
THE AGAIN STALLED FRONTAL BOUNDARY.
LATE TONIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE WILL
HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW ENGLAND.
ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A
GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS
ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY
INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS
PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE
MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...PC
AVIATION...AMS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
143 AM EDT SAT AUG 30 2014
.SYNOPSIS...
A STALLED FRONTAL BOUNDARY NEAR THE SOUTH CAROLINA...NORTH
CAROLINA BORDER WILL MOVE GRADUALLY NORTH TONIGHT THROUGH
SATURDAY...AND BE POSITIONED OVER NORTHERN VIRGINIA BY SATURDAY
AFTERNOON. A MORE SUBSTANTIAL COLD FRONT WILL APPROACH THE AREA
SATURDAY NIGHT AND MOVE THROUGH THE AREA SUNDAY AND SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 820 PM EDT FRIDAY...
EVENING SOUNDINGS SHOW MOISTURE TRAPPED BENEATH THE INVERSION AT
85H AIDED BY SHALLOW SE FLOW NORTH OF THE RESIDUAL FRONT TO THE
SOUTH. MOST INSTABILITY THIS EVENING REMAINS OVER THE FAR SW WHERE
STILL HAVE A FEW SHOWERS ONGOING NEAR THE FRONT. THUS LEAVING IN
SOME CHANCE POPS THERE A WHILE LONGER AS THE HRRR SHOWS SOME OF
THIS COVERAGE SLIDING NORTH THROUGH MIDNIGHT. OTRW SATELLITE
DEPICTING LOW CLOUDS SPREADING BACK NORTH FROM SOUTHERN VIRGINIA
ATTM AHEAD OF THE BOUNDARY THAT WILL LIFT SLOWLY BACK NORTH
OVERNIGHT. MOST LATEST MODEL SOLUTIONS SHOW LOW CLOUDS REMAINING
ALONG/EAST OF THE BLUE RIDGE THROUGH MORNING WITH ONLY THE FAR
SOUTH AND WEST STAYING MORE PC ALONG THE PERIMETER OF THE WEAK
WEDGE. SHOWER CHANCES ELSW REMAIN IFFY GIVEN LOSS OF HEATING WITH
THE BOUNDARY ACROSS THE REGION LATE. LATEST NAM AND TO SOME DEGREE
THE HRRR WANT TO DEVELOP A FEW SHRA CLUSTERS ALONG AND JUST EAST
OF THE BLUE RIDGE AFTER MIDNIGHT...WHILE MOST OTHERS DRY OR
FARTHER SOUTH WITH ISOLATED COVERAGE. SINCE ALREADY HAVE SOME
ISOLATED POPS GOING AND SEEING SOME INSTABILITY ABOVE THE
INVERSION...WILL LEAVE IN AND EXTEND INTO SOUTHSIDE VIRGINIA
OVERNIGHT. OTRW FOG/LOW CLOUDS LOOK ON TRACK WITH JUST SOME UPWARD
ADJUSTS TO LOW TEMPS GIVEN THE CLOUD CANOPY AND MOIST DEWPOINTS
OVERNIGHT.
WE EXPECT A BREAK IN THE PRECIPITATION SATURDAY MORNING WITH THE
FORCING ASSOCIATED WITH THE FRONT NORTH OF THE REGION.
HOWEVER...BY THE AFTERNOON...ENOUGH DAYTIME HEATING IS EXPECTED TO
REFIRE SHOWERS AND PERHAPS A FEW THUNDERSTORMS IN THE NORTHERN
PARTS OF THE REGION CLOSEST TO THE NEW LOCATION OF THE STALLED
FRONT. ALSO...INCREASING SOUTHERLY WINDS WILL FOCUS UPSLOPE
ISOLATED SHOWER AND THUNDERSTORM POTENTIAL ALONG THE CREST OF THE
BLUE RIDGE.
LOW TEMPERATURES TONIGHT WILL BE A MIX OF LOW TO MID 60S ACROSS THE
MOUNTAINS WITH MID TO UPPER 60S ACROSS THE PIEDMONT. ON
SATURDAY...HIGH TEMPERATURES IN THE LOW TO MID 80S WILL BE COMMON IN
THE MOUNTAINS WITH UPPER 80S TO NEAR 90 ACROSS THE PIEDMONT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 330 PM EDT FRIDAY...
UPPER LEVEL RIDGE FORECAST OVER THE SOUTHEASTERN CONUS TO REMAIN IN
PLACE IN THE SHORT-TERM WITH THE MAIN WEATHER FEATURE A SERIES OF
SOUTHERN STREAM SHORT-WAVES EXPECTED TO TRACK FROM THE GULF COAST
NORTHEAST INTO THE OHIO VALLEY. 12Z MODEL RUNS OF GFS/NAM/EURO
SHOWING THIS FEATURE OR SERIES OF FEATURES TRACKING SOMEWHAT
FURTHER WEST THAN PREVIOUS RUNS DUE PARTLY TO THE STRONG RIDGE.
AXIS OF HEAVIEST RAINFALL SHOULD STAY WEST OF OUR CWA BUT STILL
HAVE LIKELY POPS IN THE FAR WEST ON SUNDAY TAPERING TO CHANCE
ACROSS THE PIEDMONT ON SUNDAY. RIDGE FLATTENS SOMEWHAT ON MONDAY
AS UPPER TROUGH ENERGY REMAINS WILL NORTH BUT WILL STILL BE
CHANCES FOR MAINLY AFTERNOON SHOWERS AND SCATTERED THUNDERSTORMS
MONDAY AFTERNOON. TEMPS WILL REMAIN WARM THROUGH THE PERIOD WITH
MAINLY 80S FOR HIGHS AND 60S FOR LOWS EVEN WITH CONSIDERABLE
CLOUDS ON SUNDAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...
FLAT UPPER RIDGE IS EXPECTED TO DOMINATE OUR MID-WEEK WEATHER
PATTERN ACROSS THE CENTRAL APPALACHIAN AND MID-ATLANTIC REGION. THIS
SHOULD MAINTAIN SUMMER-LIKE TEMPERATURES THROUGH THE ENTIRE PERIOD
WITH HIGHS NEAR 90F IN THE PIEDMONT AND MID-80S IN THE MOUNTAINS
ALONG WITH NIGHT-TIME LOWS IN THE 60S TO LOW 70S. COULD END UP BEING
ONE OF THE WARMEST WEEKS OF THE SUMMER EVEN AS THE SO-CALLED
METEOROLOGICAL SUMMER ENDS ON AUGUST 31. PRECIPITATION WILL ALSO
GENERALLY BE OF SUMMER-LIKE CHARACTER WITH DIURNALLY DRIVEN
CONVECTION PROVIDING THE BEST CHANCES FOR RAINFALL. WEDNESDAY
AFTERNOON LOOKS LIKE THE MOST PROMISING DAY FOR STORMS AS WEAK
FRONTAL BOUNDARY PUSHES ACROSS THE CWA. THURSDAY AND FRIDAY LIKELY
TO BE DRIER ALTHOUGH WIDELY SCATTERED SHOWERS STILL POSSIBLE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 140 AM EDT FRIDAY...
BROAD AREA OF STRATUS HAD SPREAD WEST ACROSS THE REGION. THE
WESTERN EDGE WAS CLOSE TO KLWB AND KBLF. THESE AIRPORTS MAY GO
BACK AND FORTH BETWEEN SCATTERED VFR CLOUDS AND MVFR CEILINGS
THROUGH 14Z/10AM. FOR KBCB/KROA/KDAN AND KLYH HIGHER CONFIDENCE
THAT CEILINGS WILL LOWER TO MVFR OR IFR.
IMPROVEMENT IN CONDITIONS WILL BE SLOW THIS MORNING AS A FRONT
LIFTS NORTH THROUGH THE AREA. ONLY MEDIUM CONFIDENCE AS TO WHEN
CEILINGS WILL LIFT BACK TO VFR. THE THREAT OF SHOWERS AND
THUNDERSTORMS THROUGH THE TAF PERIOD REMAINS LOW ENOUGH TO KEEP
OUT OF THE FORECAST FOR NOW.
EXTENDED DISCUSSION...
ANY ISOLATED OR SCATTERED SHOWERS AND STORMS WILL BE MAINLY
ALONG AND NORTH OF A KHSP-KFVX LINE THIS EVENING...JUST SOUTH OF
THE AGAIN STALLED FRONTAL BOUNDARY.
LATE TONIGHT THROUGH SUNDAY EVENING AN AREA OF LOW PRESSURE WILL
HEAD EASTWARD THROUGH THE GREAT LAKES REGION TOWARD NEW ENGLAND.
ITS ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE REGION BRINGING A
GENEROUS COVERAGE OF SHOWERS AND SOME STORMS. SUB-VFR CONDITIONS
ARE EXPECTED TO ACCOMPANY THE SYSTEM AND PRECIPITATION.
ANOTHER COLD FRONT IS EXPECTED TO PRODUCE SIMILAR CONDITIONS TUESDAY
INTO WEDNESDAY. HOWEVER...MODEL GUIDANCE FOR THIS ONE OFFERS
PRECIPITATION IN A MORE SCATTERED DISTRIBUTION. AS SUCH...THE
MAGNITUDE OF SUB-VFR CONDITIONS MAY BE LESS.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS/JH
SHORT TERM...PC
LONG TERM...PC
AVIATION...AMS/JH
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS PORTLAND OR
300 PM PDT SAT AUG 30 2014
.SYNOPSIS...COOLER WESTERLY FLOW ALOFT PREVAILS THROUGH THIS
WEEKEND..WITH A SERIES OF WEAK SURFACE FRONTS. THIS WILL BRING
PLENTY OF CLOUDS AND COOLER AIR TO THE REGION...ALONG WITH PERIODIC
RAIN SHOWERS. THE BEST CHANCES OF SHOWERS WILL BE THIS AFTERNOON AND
EVENING. WEAK RIDGING TRIES TO BUILD BACK INTO THE PACIFIC
MONDAY...BEFORE A DEEPER TROUGH MOVES OVER THE AREA TUESDAY THROUGH
THE END OF THE WEEK.
&&
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...
A DISCONNECTED LINE OF MODERATE SHOWERS HAS DEVELOPED ALONG A WEAK
FRONT CURRENTLY MOVING ACROSS THE VALLEY. CURRENT ORIENTATION OF THE
JET STREAM PUTS US IN THE AREA OF FAVORABLE FORCING IN THE LEFT EXIT
REGION WHICH HAS HELPED TO PRODUCE STRONGER SHOWERS THIS AFTERNOON
AND EVEN A LONE LIGHTNING STRIKE IN NORTHERN MARION COUNTY AROUND 145
PM. AS EXPECTED...RAIN HAS MOSTLY CLEARED OUT ON THE COAST BEHIND THE
FRONT WITH THE EXCEPTION OF A BAND OF LIGHT SHOWERS NEAR NEWPORT
WHICH MAY BE A SIDE EFFECT OF COLOCATION WITH THE JET STREAK. CLOUDS
WILL LINGER BEHIND THE FRONT BUT THERE SHOULD BE ENOUGH BREAKS
OVERNIGHT TO COOL DOWN A COUPLE OF DEGREES MORE THAN LAST NIGHT.
ANOTHER WEAK FRONT WILL MOVE ACROSS THE AREA SUNDAY. THE CHANCE FOR
RAIN IS WEAKER WITH THIS SYSTEM AS THE UPPER JET SHIFTS
NORTHWARD...REDUCING ATMOSPHERIC LIFT. THE PRECIPITATION ON
SUNDAY WILL BE VERY LIGHT AND BE RESTRICTED TO THE NORTHERNMOST PART
OF THE FORECAST AREA WITH MODELS CONTINUING TO TREND DOWNWARD WITH
POPS. AN UPPER RIDGE WILL BUILD MONDAY...BUT THE MODELS HAVE BEEN
BACKING OFF ON THE STRENGTH OF THE RIDGE AND EXPECT ANOTHER WEAK
FRONT TO CLIP THE NORTHERN AREAS MONDAY AFTERNOON AND EVENING.
RIDGING TRIES TO ESTABLISH ITSELF ON TUESDAY BUT AN UPPER LEVEL
TROUGH STARTS TO DIG INTO SE BRITISH COLUMBIA. ALTHOUGH WEAK...AN
ARGUMENT COULD BE MADE FOR SOME ENHANCED FORCING DUE TO A WEAK JET
STREAK MOVING INTO NW WASHINGTON SO OVERALL DECREASED POPS TUESDAY
BUT KEPT THEM MENTIONABLE ACROSS THE SW WASHINGTON PART OF THE
FORECAST AREA. BOWEN/TJ
.LONG TERM...THE MODELS CONTINUE TO HINT AT A TROUGH MOVING INTO THE
PACIFIC NORTHWEST ON TUESDAY. THIS TROUGH LOOKS TO STICK AROUND
THROUGH THE END OF NEXT WEEK. STILL KEEPING A SLIGHT CHANCE OF
SHOWERS IN THE FORECAST THROUGH THURSDAY FOR THE NORTHERN PORTIONS
OF THE CWA. TEMPERATURES WILL TREND TOWARDS SEASONAL NORMALS. LATE
NEXT WEEK THE MODELS CONTINUE TO TRY TO DEVELOP A CUTOFF
LOW...HOWEVER...DIFFERENCES BETWEEN THE VARIOUS MODELS AND MODEL
RUNS HAVE CREATED A LOT OF UNCERTAINTY. STILL LEANING TOWARDS IT
BEING DRIER AND SLIGHTLY WARMER FOR NEXT WEEKEND.
&&
.AVIATION...LIGHT SHOWERS WILL CONTINUE THROUGH THIS
EVENING...THEN GRADUALLY DECREASE FROM SOUTH TO NORTH. MOSTLY A
MIX OF MVFR AND VFR CONDITIONS INLAND...WITH IFR CONDITIONS
LIKELY IN SHOWERS. MOIST ONSHORE FLOW PERSISTS OVERNIGHT...LIKELY
BRINGING SOME 2000-2500 FT CIGS NEAR SUNRISE EARLY SUNDAY AM ALONG
THE LOWER COLUMBIA RIVER. OTHERWISE...MOST INLAND SITES WILL
REMAIN VFR WITH CIGS AROUND 5000 FT. COASTAL SITES WILL REMAIN
MVFR AND IFR THROUGH SUNDAY AM.
KPDX AND APPROACHES...MIX OF MVFR AND VFR CONDITIONS WITH CIGS
BETWEEN 2500-3500 FT. EXPECT LOWER CONDITIONS IN SHOWERS THROUGH
04-06Z SUNDAY. A FEW 2000 FT CIGS ARE EXPECTED AGAIN FROM 14-17Z
SUNDAY. /27
&&
.MARINE...AFTER A WEAK FRONTAL PASSAGE EARLIER TODAY...THE NEXT
STRONGER FRONT MOVES ACROSS THE COASTAL WATERS LATE SUNDAY. MODELS
SHOW LIGHT SW WINDS THROUGH SUNDAY...BEFORE BACKING TO THE NW BY
MONDAY. THE SEAS WILL COMPRISE OF A SMALL SW SWELL OF 1 TO 2
FEET AT AROUND 15 SECONDS AND A NORTHWEST FRESH SWELL FROM THE
GULF OF ALASKA AROUND 9 TO 10 SECONDS. LIGHT WIND WAVES THE NEXT
COUPLE OF DAYS. A NW SWELL WILL BUILD TONIGHT AND PEAK AROUND 6
FEET ON SUNDAY. HIGH PRESSURE WILL REBUILD MONDAY NIGHT AND
TUESDAY AND PERSISTENT NORTHERLY WINDS WILL RETURN TO THE WATERS.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&
$$
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
Area Forecast Discussion
National Weather Service Spokane WA
245 PM PDT SAT AUG 30 2014
.SYNOPSIS...
The Labor Day weekend will be cooler than normal, with locally
breezy conditions. Aside from isolated showers, the majority of
the Inland Northwest will remain dry. A continued cool pattern is
expected through the middle of next week, with the best chance for
showers and thunderstorms Wednesday. Relatively warmer, drier
weather is forecast late next week.
&&
.DISCUSSION...
Tonight and Sunday: A weak shortwave disturbance is bringing
isolated to scattered showers across the region. This shower
activity will continue to track east across the southern half of
the forecast area, generally along and south of Highway 2. This
will continue this evening and eventually move into the Idaho
panhandle. Oddly enough, the location of persistent showers is in
the area that models forecast to be in between the split flow of
energy. GFS/EC/NAM/SREF all show split flow with the bulk of the
shortwave energy either along our northern border or across
northern Oregon. The 15Z HRRR had a very good handle on the precip
but later runs showed the same split flow of other models. The
evening forecast is based on the 15Z HRRR which remains on track.
Thunder chances remain rather low but we might see a strike or two
across the extreme southeast corner of the forecast area this
evening. Overnight and into Sunday the Idaho panhandle will see
continued shower activity as westerly flow enhances ascent. Breezy
winds will continue tonight which will keep overnight lows from
bottoming out. If the sheltered northern valleys clear out at all
tonight there could be a few spots approaching the freezing mark.
Expect mainly dry conditions for the low lands Sunday with high
temperatures in the 70s. Isolated mountain showers will linger
over the Idaho panhandle but instability will be marginal for
thunder. /Kelch
Sunday Night through Tuesday: There are no notable changes to the
previous fcst, centering our focus on gusty winds near the
Cascades as well as pcpn chances. Rising hts aloft Sunday night
and Monday in NW steering flow will lead to stabilization aloft as
the jet axis translates slowly NE ahead of the significant upper
trough and mainly dry cold front across Srn BC Tuesday. Given the
lack of sfc-based and nocturnal elevated instability, we don`t
have much of a chance of pcpn in the fcst for any zone...and have
limited these chances to the Cascades and NE Wa and N Idaho
Panhandle mtns Sunday night and late Tuesday. However, pressure
gradients will increase ahead of the aforementioned trough and
help to keep gusty winds in the fcst. bz
Tuesday night through Saturday: A few showers and cool conditions
mark the beginning of this period, followed by a warming and
drying trend. A trough of low pressure migrates east-southeast
across the region Tuesday night to Wednesday night. A weak
deformation axis sagging in from the north, coupled with the lift
and instability associated with the trough, will bring shower
chances to the Cascades and northern counties. Some showers may
develop as far south as the Highway 2/I-90 corridor, from the
Waterville Plateau eastward, Wednesday afternoon/evening. As for
thunder prospects, I wouldn`t rule out some mixed with the
showers overnight into Wednesday morning, particularly toward the
northeast WA and north ID mountains where an area of moderately
unstable high level total totals values are depicted. However the
better thunderstorm threat comes Wednesday afternoon and evening
with increased SBCAPE. Overnight Wednesday the main trough shifts
east, taking the better instability and shower threat with it.
From Thursday to Saturday model agreement falters some. However,
loose agreement suggests a baggy trough over the western U.S. and
the Inland NW in a north to northwesterly flow. Weak mid-level
impulses in that flow and at least a suggestion of afternoon
instability toward the northern Rockies will keep shower chances
alive over the ID Panhandle. Otherwise the latter part of next
week looks dry, with just a few clouds. /J. Cote`
&&
.AVIATION...
18Z TAFS: VFR conditions expected through 18Z Sunday. A couple of
weak weather disturbances today will produce mainly mountain
showers. Breezy conditions will develop by early afternoon in the
post frontal air mass. Models are hinting at some low level
moisture advection across southeastern WA tonight. This is
expected to produce some mid level cloud cover across eastern WA
and showers ongoing over the ID Panhandle. This should not impact TAF
sites although KCOE and KPUW may see some vicinity showers 06Z-12Z
Sunday. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 52 71 51 75 49 76 / 20 10 10 0 0 0
Coeur d`Alene 50 69 47 74 46 75 / 20 10 10 0 0 0
Pullman 48 70 45 74 43 77 / 20 10 10 0 0 0
Lewiston 56 77 55 81 54 84 / 20 10 10 0 0 0
Colville 46 75 43 78 44 78 / 10 10 10 10 10 10
Sandpoint 46 68 43 72 45 73 / 20 20 20 10 10 10
Kellogg 49 65 47 69 47 71 / 30 30 10 10 10 0
Moses Lake 52 78 50 81 51 81 / 20 0 0 0 0 0
Wenatchee 57 77 56 80 56 80 / 20 0 0 0 0 0
Omak 52 78 51 81 52 80 / 10 0 10 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
703 PM CDT SUN AUG 31 2014
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SYNOPSIS...
ISSUED AT 218 PM CDT SUN AUG 31 2014
WARM AND RATHER HUMID WITH SHOWERS AND THUNDERSTORMS AT TIMES FOR
THE REST OF THE HOLIDAY WEEKEND AND THROUGH THE UPCOMING WORK
WEEK.
STG SUBTROPICAL RIDGE ACRS THE SRN CONUS WL EXPAND NWD A BIT AS
SOMEWHAT PROGRESSIVE BAND OF WESTERLIES GRADUALLY RECEDES NWD
DURING THE PERIOD. NOTHING SPECIAL ABOUT THIS PATTERN FOR THIS
TIME OF YEAR...AS THE WESTERLIES ARE TYPICALLY STRONGER THAN
DURING THE MIDDLE SUMMER...BUT ARE STILL USUALLY CENTERED N OF THE
AREA.
THE PRIMARY FRONTAL ZONE SEPARATING WARM AND VERY MOIST TROPICAL
AIR TO THE S FM COOLER AND DRIER CANADIAN AIR TO THE N WL REMAIN
STETCHED OUT W-E ALONG THE SRN EDGE OF THE MAIN WESTERLIES...AND
CLOSE TO THE FCST AREA MUCH OF THE TIME. THIS WL RESULT IN
SEVERAL OPPORTUNITIES FOR PCPN...LIKELY RESULTING IN ABV NORMAL
AMNTS. TEMPS ARE EXPECTED TO REMAIN AOA NORMAL FOR MUCH OF THE
FCST PERIOD BEFORE DROPPING BACK CLOSE TO NORMAL LATE. IT WILL
ALSO BE HUMID AT TIMES.
&&
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 218 PM CDT SUN AUG 31 2014
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW
PRESSURE MOVING NORTHEAST OVER FAR NORTHWEST MINNESOTA AND A COLD
FRONT MOVING EASTWARD FROM THE LOW TO THE CENTRAL GREAT PLAINS.
STORMS HAVE BEGUN TO FIRE ALONG THE FRONT OVER SOUTH CENTRAL
MINNESOTA...BUT THE ATMOSPHERE IS STRUGGLING TO DESTABILIZE DUE IN
PART TO A PRONOUNCED CAP AND DRY AIR ON THE 18Z MINNEAPOLIS
SOUNDING. HOWEVER...AS A SHORTWAVE OVER NEBRASKA MOVES INTO THE
NORTHERN MISSISSIPPI VALLEY...THE CAP IS EXPECTED TO WEAKEN LATE
THIS AFTERNOON THAT WILL RESULT IN A FAVORABLE ENVIRONMENT FOR
SEVERE STORMS. THESE STORMS COULD MOVE INTO NORTH-CENTRAL WISCONSIN
LATER THIS EVENING. THE MAIN SHORTWAVE IS MOVING EAST OVER EASTERN
WYOMING AND ANTICIPATED TO ARRIVE INTO WISCONSIN LATE TONIGHT INTO
MONDAY MORNING...ALONG WITH THE COLD FRONT. THUNDERSTORM TIMING AND
IMPACTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...A COLD FRONT WILL SLOWLY MOVE ACROSS THE NORTHERN
MISSISSIPPI VALLEY AS IT WAITS FOR A SHORTWAVE OVER WYOMING TO GIVE
IT A FORWARD PUSH. ASSUMING STRONG TO SEVERE CONVECTION AHEAD OF
THE FRONT DEVELOPS AS PLANNED LATER THIS AFTERNOON INTO THIS
EVENING...GUIDANCE SUGGESTS THIS CONVECTION WILL MAKE A RUN AT
NORTH-CENTRAL WISCONSIN LATE THIS EVENING...THOUGH WILL BE WEAKENING
AS DIURNAL INSTABILITY IS LOST. MODELS SUGGEST AROUND 1000 J/KG OF
ELEVATED CAPE WILL BE PRESENT AS THIS CONVECTION APPROACHES THE
NORTHWEST FORECAST AREA SO NOT OUT OF THE QUESTION THAT A FEW STRONG
STORMS COULD REACH NORTH-CENTRAL WISCONSIN. AN ISOLATED SEVERE
STORM CANNOT BE RULED OUT...MAINLY FOR DAMAGING WINDS AND LARGE
HAIL. WOULDNT BE SURPRISE TO SEE A FEW HOUR BREAK OVERNIGHT BETWEEN
THIS CONVECTION AS IT WEAKENS/LIFTS TO THE NORTHEAST...AND A MORE
WIDESPREAD AREA OF SHOWERS AND THUNDERSTORMS AHEAD OF THE MAIN
SHORTWAVE WHICH WILL MOVE INTO THE NORTHERN MISSISSIPPI VALLEY BY
12Z. THIS AREA OF PRECIP SHOULD MOVE ACROSS CENTRAL AND
NORTH-CENTRAL WI LATE TONIGHT. ELEVATED CAPES LOOK TO BE APPROX 500
J/KG SO NOT ANTICIPATING SEVERE CONVECTION. LOWS MAINLY IN THE
MIDDLE 60S.
MONDAY...THE SHORTWAVE TROUGH WILL LIFT NORTHEAST ACROSS WISCONSIN
MONDAY MORNING...DRIVING THE AREA OF SHOWERS AND THUNDERSTORMS
ACROSS NORTH-CENTRAL AND NORTHEAST WISCONSIN. THE HEAVIEST RAINFALL
LOOKS TO OCCUR OVER CENTRAL AND NORTH-CENTRAL WISCONSIN WITH THIS
EVENT AND COULD SEE AN INCH TO 1.50 INCHES IF CONVECTION REACHES
INTO THIS AREA THIS EVENING. WITH PRECIPITATION OCCURRING DURING
THE MORNING AND THE SHORTWAVE LIFTING NORTHEAST OF THE AREA IN THE
AFTERNOON...SEEMS LIKE AN AWFULLY SMALL TIME PERIOD FOR
REDEVELOPMENT OF STORMS ALONG THE COLD FRONT OVER NORTHEAST
WISCONSIN. THE BEST BET MAY BE TO HAVE STORMS CONTINUOUSLY REFIRE
ALONG THE TAIL OF THE SHORTWAVE...BUT THIS ADMITTEDLY SEEMS LIKE
A SMALL CHANCE SINCE THE ATMOSPHERE WILL HAVE BEEN WORKED OVER
BY THIS TIME...AND PRECIPITATION WILL HAVE SQUASHED SURFACE BASED
INSTABILITY. AS A RESULT...SPC HAS SHIFTED THE SLIGHT RISK OF
SEVERE WEATHER TO THE SOUTH AND EAST OF THE FORECAST AREA AND THIS
SEEMS REASONABLE. WILL MENTION THE CHANCE OF GUSTY WINDS AND SMALL
HAIL BUT LEAVE THE THREAT OF SEVERE WEATHER OUT OF THE HWO.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 218 PM CDT SUN AUG 31 2014
SOME LINGERING PCPN WL BE POSSIBLE MON EVENING...MAINLY OVER E-C
WI. CARRIED CHC POPS INTO THE EARLY EVENING. WHILE ISOLD SHRA
COULD LINGER WELL INTO THE NGT...THE MAIN POOL OF INSTABILITY WL
BE WELL S BY THEN...SO OPTED TO GO WITH A DRY FCST AFTER MIDNIGHT.
LATER SHIFTS MAY NEED TO TAKE ANOTHER LOOK AT THAT.
THERE ARE PROS AND CONS FOR PCPN CHCS TUE. ON ONE HAND...UPR TROF
WL STILL BE ACRS THE AREA DURING THE MORNING...AND WNWLY UPR FLOW
WL KEEP MODEST MID-LVL LAPSE RATES ACRS THE RGN. ON THE OTHER...
UPR HEIGHTS WL BE RISING AS THE TROF SHIFTS E...AND QG FORCING
WL BE FAVORING SUBSIDENCE. OPTED TO KEEP FAIRLY LOW POPS...BUT
WENT WITH ISOLD SHRA ACRS ALL BUT THE FAR SRN PART OF THE AREA.
PCPN UNLIKELY TO BE A BIG DEAL...BUT CONFIDENCE IN TOTALLY DRY DAY
ISN/T THAT GREAT EITHER.
UPR HEIGHTS SHOULD CONT TO RISE TUE NGT/WED. STAYED DRY TUE NGT...
BUT N-C WI WL BE CLOSE ENOUGH TO THE RETURN FLOW TO JUSTIFY
HAVING A CHC OF TSRA WED.
WENT WITH A BLEND OF TOP PERFORING GUIDANCE PRODUCTS FOR TEMPS...
WHICH WERE DOMINATED BY THE ECMWF AND IT/S MOS AND BIAS-CORRECTED
DERIVATIVES.
NO SIG CHGS NEED TO BROAD-BASED EXTENDED FCST INITIALIZATION
GRIDS.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 647 PM CDT SUN AUG 31 2014
IFR STRATUS HAS MOVED OFF LAKE INTO LAKESHORE COUNTIES AND PARTS
FOX VALLEY. INCREASING WINDS AT LOW LEVELS MID TO LATE EVENING
SHOULD DIMINSH THIS STRATUS. A COLD FRONT WILL MOVE ACROSS THE
REGION LATE TONIGHT INTO MONDAY...SCATTERED MVFR CIGS AND
VSBYS...LOCALLY IFR...WILL DEVELOP DUE TO HEAVY RAIN AND POSSIBLE
THUNDERSTORMS. SOME STORMS MAY CONTAIN STRONG GUSTY WINDS AS THEY
MOVE INTO CENTRAL AND NORTH-CENTRAL WISCONSIN LATE IN THE EVENING
AND OVERNIGHT. HAVE ADDED TS TO TAFS WITH THIS ISSUANCE...THOUGH
CURRENT ACTIVITY OVER WESTERN EXPECTED TO STAY WEST OF TAF SITES
THROUGH MIDNIGHT GIVEN MORE STABLE AIR MASS OVER EASTERN WI. &&
.GRB WATCHES/WARNINGS/ADVISORIES...
BEACH HAZARDS STATEMENT FROM MONDAY MORNING THROUGH MONDAY
EVENING FOR WIZ022-040-050.
&&
$$
SYNOPSIS.......SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......SKOWRONSKI
AVIATION.......TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1248 PM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES TODAY AND FROM
SUNDAY NIGHT INTO MONDAY.
LOCAL AND REGIONAL RADARS SHOWING A LARGE AREA OF RAIN LIFTING
NORTHEAST ACROSS EASTERN MINNESOTA AND MUCH OF WISCONSIN. SOME
TRAILING RAIN STILL BACK ACROSS EASTERN IOWA.
EXPECT THE RAIN TO CONTINUE LIFTING NORTHEAST THIS MORNING AS THE
SURFACE LOW JUST ENTERING WESTERN WISCONSIN ALSO CONTINUES TO MOVE
NORTHEAST IN CONJUNCTION WITH THE UPPER LEVEL TROUGH. THE 30.04Z
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING RAIN AND SHOWS
THE BACK EDGE ALONG THE MISSISSIPPI RIVER BY 12Z WITH MOST OF THE
AREA DRY BY 18Z. THIS IS VERY SIMILAR TO WHAT THE 30.00Z HI-RES
ARW AND NMM SHOW AND WILL PLAN TO TREND THE RAIN CHANCES IN THIS
DIRECTION. THE QUESTION THEN BECOMES IF ADDITIONAL ACTIVITY WILL
DEVELOP THIS AFTERNOON. THE 30.00Z NAM AND GFS BOTH BRING A
TRAILING SHORT WAVE TROUGH ACROSS THE AREA THIS AFTERNOON. IT DOES
APPEAR IN THE WATER VAPOR IMAGERY THAT THIS WAVE DOES EXIST AND IS
OVER EASTERN SOUTH DAKOTA. HOWEVER...THE WATER VAPOR IMAGERY ALSO
SHOWS A LOT OF DRY AIR IN PLACE BEHIND THE DEPARTING SHORT WAVE
TROUGH AND THE CONCERN BECOMES WHETHER THIS SECONDARY SHORT WAVE
TROUGH WILL HAVE ENOUGH FORCING TO CAUSE SOME ADDITIONAL
DEVELOPMENT. THE HRRR IS SUGGESTING THAT SOME COULD START TO FORM
EARLY IN THE AFTERNOON WHICH IS SIMILAR TO THE NAM AND GFS WHILE
THE ARW AND NMM REMAIN DRY THROUGH THE AFTERNOON. WITH ALL THE DRY
AIR...TEND TO FEEL THE ARW AND NMM HAVE THE MORE CORRECT SOLUTION
BUT WILL HOLD ONTO A SMALL RAIN CHANCE JUST IN CASE SOMETHING DOES
POP UP.
AFTER SOME WEAK UPPER LEVEL RIDGING MOVES OVER THE UPPER MIDWEST
TONIGHT AND SUNDAY...THE NEXT SYSTEM WILL TAKE AIM AT THE REGION.
WATER VAPOR IMAGERY ALREADY SHOWS IT APPROACHING THE PACIFIC
NORTHWEST COAST AND IT IS EXPECTED TO MOVE QUICKLY ACROSS THE
NORTHERN ROCKIES AND ACROSS THE UPPER MIDWEST SUNDAY NIGHT AND
MONDAY. THE GFS AND 30.00Z ECMWF BOTH CONTINUE TO SHOW THIS SYSTEM
PRODUCING MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB LAYER
LATE SUNDAY NIGHT INTO MONDAY MORNING. THE GFS SHOWS STRONG
ISENTROPIC UP GLIDE SHOULD SPREAD ACROSS THE AREA SUNDAY NIGHT
AHEAD OF THE SHORT WAVE TROUGH WITH UP TO 10 UBAR/S ON THE 305K
SURFACE. THE NOSE OF THE LOW LEVEL JET IS EXPECTED TO BECOME
ORIENTED INTO THE AREA SUNDAY EVENING WITH LITTLE MOVEMENT SUNDAY
NIGHT BEFORE VEERING OFF TO THE EAST MONDAY MORNING. WITH THE
AMPLE FORCING...WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO MOVE
IN SUNDAY EVENING AND WORK EAST ACROSS THE AREA BEFORE ENDING
MONDAY AFTERNOON. GOOD CAPE WILL BUILD SUNDAY AFTERNOON WEST OF
THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS SYSTEM. THE
GFS SUGGESTS THAT AN AXIS OF 1000-1500 J/KG OF ML CAPE WILL
PERSIST AHEAD OF THE FRONT THROUGH THE NIGHT AS THE SYSTEM WORKS
ACROSS THE AREA. GOOD SHEAR LOOKS TO OVERSPREAD THE REGION WITH 40
TO 50 KNOTS OF 0-6KM SHEAR...BUT MOST OF THIS LOOKS TO BE IN THE
0-3KM LAYER WITH 35 TO 40 KNOTS. EXPECT THAT THIS WILL BE
SUFFICIENT TO SUPPORT SOME STRONG TO SEVERE STORMS WITH HAIL AND
WIND THE MAIN THREATS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
SOME SMALL RAIN CHANCES WILL CONTINUE INTO TUESDAY AS A SECONDARY
SHORT WAVE TROUGH LOOKS TO SWEEP ACROSS THE UPPER MIDWEST.
AGAIN...THERE SHOULD BE GOOD DRYING SO THE QUESTION BECOMES IF THE
FORCING WILL BE ENOUGH TO GENERATE SOME ACTIVITY. AFTER
THAT...RIDGING LOOKS TO BUILD OVER THE REGION FOR A SHORT PERIOD
WEDNESDAY AND WEDNESDAY NIGHT. THE FLOW THEN SHOULD BECOME
SOUTHWEST ALLOWING A POSITIVE TILT LONG WAVE TROUGH TO APPROACH
FROM THE NORTHWEST. DIFFERENCES BETWEEN THE ECMWF AND GFS ON HOW
FAST THIS TROUGH MOVES THROUGH WITH THE ECMWF CONSIDERABLY FASTER.
WILL HAVE SOME RAIN CHANCES WITH THIS SYSTEM BUT WILL UNDERCUT THE
MODEL CONSENSUS GRIDS SOME THINKING THE RIDGE WILL BE THE DOMINANT
FEATURE THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT AUG 30 2014
MAIN STORM CIRCULATION NOW WELL EAST OF THE AREA...BUT LOW CLOUDS
AND SHOWERS STILL WRAPPING AROUND THE CYCLONIC CIRCULATION.
VISIBLE SATELLITE IMAGERY SHOWS SOME BREAKS IN THE CLOUD AND
INDEED MODEL SOUNDINGS SHOW THE MOISTURE LAYER IS SOMEWHAT THIN.
STILL...WHERE CLEARING TAKES PLACE THE SKY QUICKLY SELF-DESTRUCTS
WITH NEW CUMULUS DEVELOPMENT. RADAR IMAGERY WAS SHOWING SOME LIGHT
SHOWERS DEVELOPING IN THESE AREAS AS WELL. SO ANTICIPATE AN
AFTERNOON AND EARLY EVENING OF MVFR TO VFR CEILINGS BETWEEN 25-35
KFT WITH OCCASIONAL LIGHT SHOWERS. TONIGHT...MODELS SUGGEST LOW
CLOUDS WILL DIMINISH AS SUBSIDENCE SETS IN. FEEL IT WILL PROBABLY
HAPPEN...BUT NOT AS QUICKLY AS MODELS INDICATE. STILL...OPTED TO
CLEAR OUT THE MVFR CEILING FOR A TIME TONIGHT. THE PROBLEM WITH
THAT...THERE IS STILL A LOT OF BOUNDARY LAYER MOISTURE
AROUND...AND AS WINDS GO LIGHT...EXPECT FOG TO FORM. PREVIOUS
FORECAST INCLUDED LIGHT FOG BUT OPTED IN ENHANCE THAT
FURTHER...ESPECIALLY AT KLSE. MIXING PICKS UP SUNDAY MORNING AHEAD
OF THE NEXT SYSTEM...SO THE FOG SHOULD QUICKLY ERODE BY 14-15Z.
&&
.HYDROLOGY...
ISSUED AT 321 AM CDT SAT AUG 30 2014
ADDITIONAL RAINFALL TODAY WILL BE A QUARTER INCH OR LESS AND THIS
WILL NOT BE ENOUGH TO CAUSE ANY FLOODING PROBLEMS. WITH THE SYSTEM
THAT WILL AFFECT THE AREA SUNDAY NIGHT AND MONDAY...CURRENT
EXPECTATIONS ARE THAT THE RAIN TOTALS WILL BE AN INCH OR LESS. THE
PRECIPITABLE WATER IS NOT EXPECTED TO BE QUITE AS HIGH WITH THE
GFS SHOWING AROUND 1.75 INCHES BUT WARM CLOUD DEPTHS WILL STILL BE
IN THE 3.5 TO 4 KM RANGE. THE SHOWERS AND STORMS WILL HAVE THE
POTENTIAL TO PRODUCE SOME HIGHER RAIN RATES...BUT WITH THE
CONVECTION EXPECTED TO BE PROGRESSIVE...IT SHOULD NOT POSE ANY
LARGE SCALE FLOODING PROBLEMS AND PLAN TO ISSUE THE LAST ESF THIS
MORNING STATING THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...MW
HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1030 AM CDT SAT AUG 30 2014
.UPDATE...RAP/WATER VAPOR ANIMATION SHOW SHORT WAVE AND ASSOCIATED
SPEED MAX LIFTING NORTHEAST. NMRS SHRA ACRS SRN WI. MES MODELS
SHOW THIS ACTIVITY LINGERING INTO THE AFTN. SECONDARY SHORTWAVE
DROPPING SEWD FROM MN NOT LIKELY TO HAVE MUCH HEATING TO WORK WITH
AS LOW CLOUD COVER WIDESPREAD. NEVERTHELESS STILL EXPECT SOME SHRA
ACTIVITY TO DOMINATE THIS AFTERNOON WITH LOW LEVEL TROUGH AXIS IN
VCNTY AND UPPER CYCLONIC FLOW PERSISTING.
PC
&&
.AVIATION/18Z TAFS/...PLENTY OF MVFR CIGS TO CONTEND WITH INTO THE
AFTN AND LIKELY THE ERLY EVE AS WELL. BROAD CYCLONIC FLOW ALONG
WITH EMBEDDED SHORTWAVES. SURFACE/850 TROUGH AXIS ALSO IN THE
VICINITY WITH ABUNDANT LOW LEVEL MOISTURE. ANY HOLES IN THE OVC
ACRS ERN MN AND NE IA FILLING RIGHT BACK IN. LOW CLOUD COVER
GRADUALLY OVERSPREADING FAR ERN WI THOUGH SLOWER TO INCREASE
THERE. WITH SOME DIURNAL DISSIPATION TO THIS CLOUD COVER...FOG
DEVELOPMENT STILL SEEMS ON TRACK WITH THE LOW LEVEL MOISTURE AND
LIGHT WIND REGIME.
PC
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SAT AUG 30 2014/
TODAY...FORECAST CONFIDENCE IS MEDIUM.
A WELL DEFINED MID LEVEL SHORT WAVE OVER CENTRAL IOWA EARLY THIS
MORNING WILL LIFT NORTHEAST AND TRACK TO NEAR GREEN BAY BY EARLY
THIS AFTERNOON. THE ASSOCIATED SURFACE LOW WILL TAKE A SIMILAR PATH.
THE FIRST ROUND OF SHOWERS AND STORMS IS EXITING TO THE NORTH OF THE
FORECAST AREA EARLY THIS MORNING. THIS STUFF WAS GENERALLY
ASSOCIATED WITH A FAVORABLE COMBINATION OF A LOW LEVEL JET AND SOME
UPPER LEVEL DIVERGENCE FROM THE RIGHT ENTRANCE REGION OF UPPER JET.
A SECOND ROUND SHOULD LIFT UP HERE BETWEEN 09-13Z THIS
MORNING...MORE DIRECTLY TIED TO THE CIRCULATION OF THE MID LEVEL
SHORT WAVE. THE HRRR DOESN/T DO MUCH WITH THIS SECOND ROUND...IN
FACT WEAKENING IT AS IT GETS UP HERE. WILL TRY TO REFINE THE TIMING
OF POPS AND COVERAGE TO MATCH THESE TRENDS. THE AFTERNOON COULD
FEATURE SCATTERED DIURNAL SHOWERS AND A POSSIBLE THUNDERSTORM AS THE
UPPER TROF AXIS MOVES THROUGH. THE SHOWERS/STORMS ARE MOVING
QUICKLY...SO DESPITE THE HIGH MOISTURE CONTENT OF THE
COLUMN...FLOODING CONCERNS ARE NIL. HIGHS WILL BE IN THE 70S WITH
DEWPOINTS REMAINING HIGH...SO IT WILL FEEL MUGGY OUT THERE.
TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
SOME OF THE MODELS ARE DEPICTING SOME SHOWERS INTO THE EVENING WITH
A SECONDARY SHORT WAVE EXITING...BUT THE COLUMN IS DRYING OUT AND
THE BEST FORCING MOVES EAST. SO AT THIS POINT...WILL CONTINUE THE
DRY FORECAST. STILL HUMID WITH ELEVATED DEWPOINTS OVERNIGHT. THE
PATTERN TURNS RATHER BAGGY WITH LIGHT TO CALM WINDS...SO WILL THROW
IN SOME PATCHY FOG AFTER MIDNIGHT.
SUNDAY AND MONDAY...FORECAST CONFIDENCE...MEDIUM
SUNDAY LOOKS LIKE A PLEASANT DAY WITH A FAIR AMOUNT OF SUNSHINE.
MODELS ARE SHOWING A WEAK WAVE PASSING THROUGH...BUT MODELS ARE
SHOWING A GOOD AMOUNT OF DRY AIR IN THE MID AND UPPER LEVELS...SO
KEPT THE FORECAST DRY. HIGH TEMPS SHOULD BE A FEW DEGREES ABOVE
NORMAL.
SHOWERS AND STORMS ARE LIKELY IN THE WEST BY DAYBREAK MONDAY
MORNING AND THEN ACROSS THE FORECAST AREA DURING THE DAY AS A
COLD FRONT MOVES THROUGH. SOME STRONG TO SEVERE STORMS ARE
POSSIBLE...BUT THIS WILL BE DEPENDENT ON THE TIMING OF THE FRONT.
IT LOOKS LIKE A DECENT AMOUNT OF INSTABILITY TO GO ALONG WITH
AROUND 45 KNOTS OF 0-6 KM BULK SHEAR. SPC DAY 3 CONVECTIVE
OUTLOOK HAS THE SOUTHERN FORECAST AREA IN A SLIGHT RISK FOR
SEVERE STORMS.
TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM
IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY AS SURFACE HIGH PRESSURE
SLIDES THROUGH THE AREA. A COUPLE MODELS ARE SHOWING A WEAK WAVE
OR TWO BRINGING SOME SPLOTCHY QPF HERE AND THERE...BUT NOT SEEING
A CONSISTENT SIGNAL AT THIS POINT SO KEPT THE FORECAST DRY.
A RETURN OF MOISTURE UNDER SOUTHERLY LOW LEVEL FLOW IS EXPECTED TO
BRING A CHANCE FOR SHOWERS AND STORMS BACK TO THE AREA THURSDAY
AND FRIDAY.
TEMPERATURES FOR THE TUESDAY THROUGH FRIDAY TIME PERIOD SHOULD
REMAIN NEAR TO A COUPLE DEGREES ABOVE NORMAL.
AVIATION/12Z TAFS/...MVFR TO IFR CIGS SHOULD OVERSPREAD SOUTHERN
WISCONSIN EARLY THIS MORNING...THEN GRADUALLY IMPROVE TO VFR THIS
AFTERNOON AS LOW PRESSURE PASSES BY TO THE NORTH. MOSTLY PLACES
SHOULD BE VFR BY 19-20Z. DRIER AIR SHOULD EVENTUALLY WORK IN ON
INCREASING SOUTHWEST THEN WESTERLY WINDS. WINDS BECOME LIGHT
TONIGHT AND WITH LINGERING HIGH DEWPOINTS...WE MAY SEE SOME PATCHY
FOG AFTER MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
SUNDAY THROUGH FRIDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
646 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES TODAY AND FROM
SUNDAY NIGHT INTO MONDAY.
LOCAL AND REGIONAL RADARS SHOWING A LARGE AREA OF RAIN LIFTING
NORTHEAST ACROSS EASTERN MINNESOTA AND MUCH OF WISCONSIN. SOME
TRAILING RAIN STILL BACK ACROSS EASTERN IOWA.
EXPECT THE RAIN TO CONTINUE LIFTING NORTHEAST THIS MORNING AS THE
SURFACE LOW JUST ENTERING WESTERN WISCONSIN ALSO CONTINUES TO MOVE
NORTHEAST IN CONJUNCTION WITH THE UPPER LEVEL TROUGH. THE 30.04Z
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING RAIN AND SHOWS
THE BACK EDGE ALONG THE MISSISSIPPI RIVER BY 12Z WITH MOST OF THE
AREA DRY BY 18Z. THIS IS VERY SIMILAR TO WHAT THE 30.00Z HI-RES
ARW AND NMM SHOW AND WILL PLAN TO TREND THE RAIN CHANCES IN THIS
DIRECTION. THE QUESTION THEN BECOMES IF ADDITIONAL ACTIVITY WILL
DEVELOP THIS AFTERNOON. THE 30.00Z NAM AND GFS BOTH BRING A
TRAILING SHORT WAVE TROUGH ACROSS THE AREA THIS AFTERNOON. IT DOES
APPEAR IN THE WATER VAPOR IMAGERY THAT THIS WAVE DOES EXIST AND IS
OVER EASTERN SOUTH DAKOTA. HOWEVER...THE WATER VAPOR IMAGERY ALSO
SHOWS A LOT OF DRY AIR IN PLACE BEHIND THE DEPARTING SHORT WAVE
TROUGH AND THE CONCERN BECOMES WHETHER THIS SECONDARY SHORT WAVE
TROUGH WILL HAVE ENOUGH FORCING TO CAUSE SOME ADDITIONAL
DEVELOPMENT. THE HRRR IS SUGGESTING THAT SOME COULD START TO FORM
EARLY IN THE AFTERNOON WHICH IS SIMILAR TO THE NAM AND GFS WHILE
THE ARW AND NMM REMAIN DRY THROUGH THE AFTERNOON. WITH ALL THE DRY
AIR...TEND TO FEEL THE ARW AND NMM HAVE THE MORE CORRECT SOLUTION
BUT WILL HOLD ONTO A SMALL RAIN CHANCE JUST IN CASE SOMETHING DOES
POP UP.
AFTER SOME WEAK UPPER LEVEL RIDGING MOVES OVER THE UPPER MIDWEST
TONIGHT AND SUNDAY...THE NEXT SYSTEM WILL TAKE AIM AT THE REGION.
WATER VAPOR IMAGERY ALREADY SHOWS IT APPROACHING THE PACIFIC
NORTHWEST COAST AND IT IS EXPECTED TO MOVE QUICKLY ACROSS THE
NORTHERN ROCKIES AND ACROSS THE UPPER MIDWEST SUNDAY NIGHT AND
MONDAY. THE GFS AND 30.00Z ECMWF BOTH CONTINUE TO SHOW THIS SYSTEM
PRODUCING MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB LAYER
LATE SUNDAY NIGHT INTO MONDAY MORNING. THE GFS SHOWS STRONG
ISENTROPIC UP GLIDE SHOULD SPREAD ACROSS THE AREA SUNDAY NIGHT
AHEAD OF THE SHORT WAVE TROUGH WITH UP TO 10 UBAR/S ON THE 305K
SURFACE. THE NOSE OF THE LOW LEVEL JET IS EXPECTED TO BECOME
ORIENTED INTO THE AREA SUNDAY EVENING WITH LITTLE MOVEMENT SUNDAY
NIGHT BEFORE VEERING OFF TO THE EAST MONDAY MORNING. WITH THE
AMPLE FORCING...WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO MOVE
IN SUNDAY EVENING AND WORK EAST ACROSS THE AREA BEFORE ENDING
MONDAY AFTERNOON. GOOD CAPE WILL BUILD SUNDAY AFTERNOON WEST OF
THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS SYSTEM. THE
GFS SUGGESTS THAT AN AXIS OF 1000-1500 J/KG OF ML CAPE WILL
PERSIST AHEAD OF THE FRONT THROUGH THE NIGHT AS THE SYSTEM WORKS
ACROSS THE AREA. GOOD SHEAR LOOKS TO OVERSPREAD THE REGION WITH 40
TO 50 KNOTS OF 0-6KM SHEAR...BUT MOST OF THIS LOOKS TO BE IN THE
0-3KM LAYER WITH 35 TO 40 KNOTS. EXPECT THAT THIS WILL BE
SUFFICIENT TO SUPPORT SOME STRONG TO SEVERE STORMS WITH HAIL AND
WIND THE MAIN THREATS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
SOME SMALL RAIN CHANCES WILL CONTINUE INTO TUESDAY AS A SECONDARY
SHORT WAVE TROUGH LOOKS TO SWEEP ACROSS THE UPPER MIDWEST.
AGAIN...THERE SHOULD BE GOOD DRYING SO THE QUESTION BECOMES IF THE
FORCING WILL BE ENOUGH TO GENERATE SOME ACTIVITY. AFTER
THAT...RIDGING LOOKS TO BUILD OVER THE REGION FOR A SHORT PERIOD
WEDNESDAY AND WEDNESDAY NIGHT. THE FLOW THEN SHOULD BECOME
SOUTHWEST ALLOWING A POSITIVE TILT LONG WAVE TROUGH TO APPROACH
FROM THE NORTHWEST. DIFFERENCES BETWEEN THE ECMWF AND GFS ON HOW
FAST THIS TROUGH MOVES THROUGH WITH THE ECMWF CONSIDERABLY FASTER.
WILL HAVE SOME RAIN CHANCES WITH THIS SYSTEM BUT WILL UNDERCUT THE
MODEL CONSENSUS GRIDS SOME THINKING THE RIDGE WILL BE THE DOMINANT
FEATURE THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 646 AM CDT SAT AUG 30 2014
LOW PRESSURE OVER CENTRAL WISCONSIN WILL CONTINUE MOVING NORTHEAST
OUT OF THE AREA TODAY. LOOK FOR SCATTERED -SHRA ACTIVITY TO
CONTINUE AT THE KRST/KLSE TAF SITES EARLY ON THIS MORNING...THEN
MOVING OUT BY 14-15Z. OTHERWISE...THERE WILL BE SOME IFR/MVFR CLOUD
COVER TO DEAL WITH IN THE WAKE OF THE LOW. LOOK FOR THE CEILINGS
TO RISE TO VFR BY LATER THIS AFTERNOON WITH DAYTIME HEATING. HIGH
PRESSURE WILL THEN SLIDE ACROSS THE AREA TONIGHT FOR SOME
CLEARING. DUE TO THE RECENT RAINFALL AND VERY MOIST LOWER BOUNDARY
LAYER...AREAS OF FOG ARE LIKELY. FOR NOW...WENT WITH 3-5SM BR AT
KRST/KLSE ALONG WITH SCATTERED STRATUS. THIS WILL HAVE TO BE
WATCHED CLOSELY FOR POSSIBLE FULL-ON IFR/LIFR CONDITIONS.
&&
.HYDROLOGY...
ISSUED AT 321 AM CDT SAT AUG 30 2014
ADDITIONAL RAINFALL TODAY WILL BE A QUARTER INCH OR LESS AND THIS
WILL NOT BE ENOUGH TO CAUSE ANY FLOODING PROBLEMS. WITH THE SYSTEM
THAT WILL AFFECT THE AREA SUNDAY NIGHT AND MONDAY...CURRENT
EXPECTATIONS ARE THAT THE RAIN TOTALS WILL BE AN INCH OR LESS. THE
PRECIPITABLE WATER IS NOT EXPECTED TO BE QUITE AS HIGH WITH THE
GFS SHOWING AROUND 1.75 INCHES BUT WARM CLOUD DEPTHS WILL STILL BE
IN THE 3.5 TO 4 KM RANGE. THE SHOWERS AND STORMS WILL HAVE THE
POTENTIAL TO PRODUCE SOME HIGHER RAIN RATES...BUT WITH THE
CONVECTION EXPECTED TO BE PROGRESSIVE...IT SHOULD NOT POSE ANY
LARGE SCALE FLOODING PROBLEMS AND PLAN TO ISSUE THE LAST ESF THIS
MORNING STATING THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...DAS
HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 AM CDT SAT AUG 30 2014
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES TODAY AND FROM
SUNDAY NIGHT INTO MONDAY.
LOCAL AND REGIONAL RADARS SHOWING A LARGE AREA OF RAIN LIFTING
NORTHEAST ACROSS EASTERN MINNESOTA AND MUCH OF WISCONSIN. SOME
TRAILING RAIN STILL BACK ACROSS EASTERN IOWA.
EXPECT THE RAIN TO CONTINUE LIFTING NORTHEAST THIS MORNING AS THE
SURFACE LOW JUST ENTERING WESTERN WISCONSIN ALSO CONTINUES TO MOVE
NORTHEAST IN CONJUNCTION WITH THE UPPER LEVEL TROUGH. THE 30.04Z
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING RAIN AND SHOWS
THE BACK EDGE ALONG THE MISSISSIPPI RIVER BY 12Z WITH MOST OF THE
AREA DRY BY 18Z. THIS IS VERY SIMILAR TO WHAT THE 30.00Z HI-RES
ARW AND NMM SHOW AND WILL PLAN TO TREND THE RAIN CHANCES IN THIS
DIRECTION. THE QUESTION THEN BECOMES IF ADDITIONAL ACTIVITY WILL
DEVELOP THIS AFTERNOON. THE 30.00Z NAM AND GFS BOTH BRING A
TRAILING SHORT WAVE TROUGH ACROSS THE AREA THIS AFTERNOON. IT DOES
APPEAR IN THE WATER VAPOR IMAGERY THAT THIS WAVE DOES EXIST AND IS
OVER EASTERN SOUTH DAKOTA. HOWEVER...THE WATER VAPOR IMAGERY ALSO
SHOWS A LOT OF DRY AIR IN PLACE BEHIND THE DEPARTING SHORT WAVE
TROUGH AND THE CONCERN BECOMES WHETHER THIS SECONDARY SHORT WAVE
TROUGH WILL HAVE ENOUGH FORCING TO CAUSE SOME ADDITIONAL
DEVELOPMENT. THE HRRR IS SUGGESTING THAT SOME COULD START TO FORM
EARLY IN THE AFTERNOON WHICH IS SIMILAR TO THE NAM AND GFS WHILE
THE ARW AND NMM REMAIN DRY THROUGH THE AFTERNOON. WITH ALL THE DRY
AIR...TEND TO FEEL THE ARW AND NMM HAVE THE MORE CORRECT SOLUTION
BUT WILL HOLD ONTO A SMALL RAIN CHANCE JUST IN CASE SOMETHING DOES
POP UP.
AFTER SOME WEAK UPPER LEVEL RIDGING MOVES OVER THE UPPER MIDWEST
TONIGHT AND SUNDAY...THE NEXT SYSTEM WILL TAKE AIM AT THE REGION.
WATER VAPOR IMAGERY ALREADY SHOWS IT APPROACHING THE PACIFIC
NORTHWEST COAST AND IT IS EXPECTED TO MOVE QUICKLY ACROSS THE
NORTHERN ROCKIES AND ACROSS THE UPPER MIDWEST SUNDAY NIGHT AND
MONDAY. THE GFS AND 30.00Z ECMWF BOTH CONTINUE TO SHOW THIS SYSTEM
PRODUCING MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB LAYER
LATE SUNDAY NIGHT INTO MONDAY MORNING. THE GFS SHOWS STRONG
ISENTROPIC UP GLIDE SHOULD SPREAD ACROSS THE AREA SUNDAY NIGHT
AHEAD OF THE SHORT WAVE TROUGH WITH UP TO 10 UBAR/S ON THE 305K
SURFACE. THE NOSE OF THE LOW LEVEL JET IS EXPECTED TO BECOME
ORIENTED INTO THE AREA SUNDAY EVENING WITH LITTLE MOVEMENT SUNDAY
NIGHT BEFORE VEERING OFF TO THE EAST MONDAY MORNING. WITH THE
AMPLE FORCING...WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO MOVE
IN SUNDAY EVENING AND WORK EAST ACROSS THE AREA BEFORE ENDING
MONDAY AFTERNOON. GOOD CAPE WILL BUILD SUNDAY AFTERNOON WEST OF
THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THIS SYSTEM. THE
GFS SUGGESTS THAT AN AXIS OF 1000-1500 J/KG OF ML CAPE WILL
PERSIST AHEAD OF THE FRONT THROUGH THE NIGHT AS THE SYSTEM WORKS
ACROSS THE AREA. GOOD SHEAR LOOKS TO OVERSPREAD THE REGION WITH 40
TO 50 KNOTS OF 0-6KM SHEAR...BUT MOST OF THIS LOOKS TO BE IN THE
0-3KM LAYER WITH 35 TO 40 KNOTS. EXPECT THAT THIS WILL BE
SUFFICIENT TO SUPPORT SOME STRONG TO SEVERE STORMS WITH HAIL AND
WIND THE MAIN THREATS.
.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 321 AM CDT SAT AUG 30 2014
SOME SMALL RAIN CHANCES WILL CONTINUE INTO TUESDAY AS A SECONDARY
SHORT WAVE TROUGH LOOKS TO SWEEP ACROSS THE UPPER MIDWEST.
AGAIN...THERE SHOULD BE GOOD DRYING SO THE QUESTION BECOMES IF THE
FORCING WILL BE ENOUGH TO GENERATE SOME ACTIVITY. AFTER
THAT...RIDGING LOOKS TO BUILD OVER THE REGION FOR A SHORT PERIOD
WEDNESDAY AND WEDNESDAY NIGHT. THE FLOW THEN SHOULD BECOME
SOUTHWEST ALLOWING A POSITIVE TILT LONG WAVE TROUGH TO APPROACH
FROM THE NORTHWEST. DIFFERENCES BETWEEN THE ECMWF AND GFS ON HOW
FAST THIS TROUGH MOVES THROUGH WITH THE ECMWF CONSIDERABLY FASTER.
WILL HAVE SOME RAIN CHANCES WITH THIS SYSTEM BUT WILL UNDERCUT THE
MODEL CONSENSUS GRIDS SOME THINKING THE RIDGE WILL BE THE DOMINANT
FEATURE THROUGH THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1134 PM CDT FRI AUG 29 2014
HEAVIEST RAINFALL HAS MOVED NORTH AND EAST OF TAF AIRFIELDS...
ALTHOUGH SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THROUGH
THE NIGHT. VISIBILITY IN THE STRONGEST OF STORMS COULD BE REDUCED
TO 1SM...BUT BIGGER CONCERN IS THE POTENTIAL FOR PATCHY FOG/MIST.
DESPITE ABUNDANT VFR/MVFR CEILINGS OVERNIGHT...RECENT RAIN HAS
RESULTED IN A NEARLY SATURATED NEAR SURFACE LAYER WITH CURRENT DEW
POINT DEPRESSIONS OF 2-3 DEGREES. WOULD EXPECT TO SEE SOME
REDUCTION IN VISIBILITY IN MIST AFTER 30.08Z IN THE 3 TO 5SM
RANGE AND POSSIBLY LOWER. WILL AMEND AS NECESSARY. CONDITIONS
WILL SLOWLY IMPROVE SATURDAY MORNING WITH A RETURN TO VFR
CONDITIONS BY THE AFTERNOON. WINDS THROUGH THE PERIOD WILL BE
LIGHT AND VARIABLE WITH A SLIGHT NORTHWEST DIRECTIONAL PREFERENCE.
&&
.HYDROLOGY...
ISSUED AT 321 AM CDT SAT AUG 30 2014
ADDITIONAL RAINFALL TODAY WILL BE A QUARTER INCH OR LESS AND THIS
WILL NOT BE ENOUGH TO CAUSE ANY FLOODING PROBLEMS. WITH THE SYSTEM
THAT WILL AFFECT THE AREA SUNDAY NIGHT AND MONDAY...CURRENT
EXPECTATIONS ARE THAT THE RAIN TOTALS WILL BE AN INCH OR LESS. THE
PRECIPITABLE WATER IS NOT EXPECTED TO BE QUITE AS HIGH WITH THE
GFS SHOWING AROUND 1.75 INCHES BUT WARM CLOUD DEPTHS WILL STILL BE
IN THE 3.5 TO 4 KM RANGE. THE SHOWERS AND STORMS WILL HAVE THE
POTENTIAL TO PRODUCE SOME HIGHER RAIN RATES...BUT WITH THE
CONVECTION EXPECTED TO BE PROGRESSIVE...IT SHOULD NOT POSE ANY
LARGE SCALE FLOODING PROBLEMS AND PLAN TO ISSUE THE LAST ESF THIS
MORNING STATING THIS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...ROGERS
HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
319 AM CDT SAT AUG 30 2014
.TODAY...FORECAST CONFIDENCE IS MEDIUM.
A WELL DEFINED MID LEVEL SHORT WAVE OVER CENTRAL IOWA EARLY THIS
MORNING WILL LIFT NORTHEAST AND TRACK TO NEAR GREEN BAY BY EARLY
THIS AFTERNOON. THE ASSOCIATED SURFACE LOW WILL TAKE A SIMILAR PATH.
THE FIRST ROUND OF SHOWERS AND STORMS IS EXITING TO THE NORTH OF THE
FORECAST AREA EARLY THIS MORNING. THIS STUFF WAS GENERALLY
ASSOCIATED WITH A FAVORABLE COMBINATION OF A LOW LEVEL JET AND SOME
UPPER LEVEL DIVERGENCE FROM THE RIGHT ENTRANCE REGION OF UPPER JET.
A SECOND ROUND SHOULD LIFT UP HERE BETWEEN 09-13Z THIS
MORNING...MORE DIRECTLY TIED TO THE CIRCULATION OF THE MID LEVEL
SHORT WAVE. THE HRRR DOESN/T DO MUCH WITH THIS SECOND ROUND...IN
FACT WEAKENING IT AS IT GETS UP HERE. WILL TRY TO REFINE THE TIMING
OF POPS AND COVERAGE TO MATCH THESE TRENDS. THE AFTERNOON COULD
FEATURE SCATTERED DIURNAL SHOWERS AND A POSSIBLE THUNDERSTORM AS THE
UPPER TROF AXIS MOVES THROUGH. THE SHOWERS/STORMS ARE MOVING
QUICKLY...SO DESPITE THE HIGH MOISTURE CONTENT OF THE
COLUMN...FLOODING CONCERNS ARE NIL. HIGHS WILL BE IN THE 70S WITH
DEWPOINTS REMAINING HIGH...SO IT WILL FEEL MUGGY OUT THERE.
.TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
SOME OF THE MODELS ARE DEPICTING SOME SHOWERS INTO THE EVENING WITH
A SECONDARY SHORT WAVE EXITING...BUT THE COLUMN IS DRYING OUT AND
THE BEST FORCING MOVES EAST. SO AT THIS POINT...WILL CONTINUE THE
DRY FORECAST. STILL HUMID WITH ELEVATED DEWPOINTS OVERNIGHT. THE
PATTERN TURNS RATHER BAGGY WITH LIGHT TO CALM WINDS...SO WILL THROW
IN SOME PATCHY FOG AFTER MIDNIGHT.
.SUNDAY AND MONDAY...FORECAST CONFIDENCE...MEDIUM
SUNDAY LOOKS LIKE A PLEASANT DAY WITH A FAIR AMOUNT OF SUNSHINE.
MODELS ARE SHOWING A WEAK WAVE PASSING THROUGH...BUT MODELS ARE
SHOWING A GOOD AMOUNT OF DRY AIR IN THE MID AND UPPER LEVELS...SO
KEPT THE FORECAST DRY. HIGH TEMPS SHOULD BE A FEW DEGREES ABOVE
NORMAL.
SHOWERS AND STORMS ARE LIKELY IN THE WEST BY DAYBREAK MONDAY
MORNING AND THEN ACROSS THE FORECAST AREA DURING THE DAY AS A
COLD FRONT MOVES THROUGH. SOME STRONG TO SEVERE STORMS ARE
POSSIBLE...BUT THIS WILL BE DEPENDENT ON THE TIMING OF THE FRONT.
IT LOOKS LIKE A DECENT AMOUNT OF INSTABILITY TO GO ALONG WITH
AROUND 45 KNOTS OF 0-6 KM BULK SHEAR. SPC DAY 3 CONVECTIVE
OUTLOOK HAS THE SOUTHERN FORECAST AREA IN A SLIGHT RISK FOR
SEVERE STORMS.
.TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM
IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY AS SURFACE HIGH PRESSURE
SLIDES THROUGH THE AREA. A COUPLE MODELS ARE SHOWING A WEAK WAVE
OR TWO BRINGING SOME SPLOTCHY QPF HERE AND THERE...BUT NOT SEEING
A CONSISTENT SIGNAL AT THIS POINT SO KEPT THE FORECAST DRY.
A RETURN OF MOISTURE UNDER SOUTHERLY LOW LEVEL FLOW IS EXPECTED TO
BRING A CHANCE FOR SHOWERS AND STORMS BACK TO THE AREA THURSDAY
AND FRIDAY.
TEMPERATURES FOR THE TUESDAY THROUGH FRIDAY TIME PERIOD SHOULD
REMAIN NEAR TO A COUPLE DEGREES ABOVE NORMAL.
&&
.AVIATION/12Z TAFS/...MVFR TO IFR CIGS SHOULD OVERSPREAD SOUTHERN
WISCONSIN EARLY THIS MORNING...THEN GRADUALLY IMPROVE TO VFR THIS
AFTERNOON AS LOW PRESSURE PASSES BY TO THE NORTH. MOSTLY PLACES
SHOULD BE VFR BY 19-20Z. DRIER AIR SHOULD EVENTUALLY WORK IN ON
INCREASING SOUTHWEST THEN WESTERLY WINDS. WINDS BECOME LIGHT
TONIGHT AND WITH LINGERING HIGH DEWPOINTS...WE MAY SEE SOME PATCHY
FOG AFTER MIDNIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION...DAVIS
SUNDAY THROUGH FRIDAY...DDV
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1053 PM MDT FRI AUG 29 2014
.UPDATE...
ISSUED AT 904 PM MDT FRI AUG 29 2014
UPDATED THE GRIDS TO REMOVE ALL MENTION OF SHOWERS AND THUNDERSTORMS
OVERNIGHT BASED ON RADAR TRENDS AND LATEST MODEL GUIDANCE. ALSO
ADJUSTED TEMPERATURES...DEWPOINTS...WINDS AND CLOUD COVER BASED
ON TRENDS.
UPDATE ISSUED AT 600 PM MDT FRI AUG 29 2014
GRIDDED FORECASTS UPDATED TO MODIFY THE EVENING POPS WITH ISOLATED
THUNDERSTORMS FROM SARATOGA TO CHEYENNE...THEN DRY AFTER 9 PM.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 150 PM MDT FRI AUG 29 2014
A WELL-DEFINED SHORTWAVE CONTINUES TO SLIDE EASTWARD ACROSS THE CWA
THIS AFTN ALONG THE NORTHERN FRINGE OF BROAD UPPER-LEVEL RIDGING IN
PLACE OVER THE CENTRAL ROCKIES. WATER VAPOR SATELLITE SHOWED THIS
FEATURE OVER NORTHEAST WY AS OF 19Z MOVING QUICKLY TOWARD SOUTHWEST
SD AND THE NORTHERN PANHANDLE. CONVECTIVE CHANCES ARE THE MAIN ISSUE
IN THE NEAR TERM. ASIDE FROM MOUNTAIN CONVECTION...SHOWER AND TSTM
CHANCES WILL BE ASSOCIATED WITH LARGER SCALE FORCING IN ADVANCE OF
THE AFOREMENTIONED WAVE. THE NAM IS STILL THE MOST BULLISH WITH QPF
OVER OUR NORTHEAST ZONES WHILE THE HRRR COMPOSITE REFLECTIVITY SHOWS
FAIRLY MODEST CONVECTIVE COVERAGE. CONFIDENCE IS FAIRLY LOW IN JUST
HOW WIDESPREAD THINGS WILL BE TODAY GIVEN WEAK SUBSIDENCE BENEATH
THE RIDGE...AND RECENT RADAR ECHOS HAVE NOT BEEN ANYTHING TO WRITE
HOME ABOUT. BELIEVE WE WILL SEE SOME MID AFTN TSTM ACTIVITY THOUGH
OVER THE HIGH PLAINS. CURRENT SPEED OF THE TROUGH AXIS SUGGESTS THE
BEST FORCING FOR ASCENT AND MOISTURE WILL SHIFT EAST OF THE CWA BY
ABOUT 22Z...AFTER WHICH TIME TSTMS SHOULD DIMINISH. DESPITE GOOD SFC
HEATING TODAY...LATEST SPC MESOSCALE ANALYSIS INDICATES LESS THAN
1000 J/KG OF SBCAPE. LLVL FLOW OUT OF THE NORTH OR NORTHWEST IS NOT
CONTRIBUTING TO ANY REASONABLE SHEAR PROFILES EITHER SO ANY STRONGER
STORMS SHOULD NOT BE WIDESPREAD THOUGH THEY ARE POSSIBLE. IT SHOULD
BE A QUIET OVERNIGHT WITH AS SUBSIDENCE INCREASES OVER THE CWA. DO
NOT EXPECT FOG DEVELOPMENT TONIGHT WITH UNFAVORABLE LLVL WINDS...BUT
CANNOT RULE IT OUT IN THE PLATTE RIVER VALLEY IF WINDS ARE MORE
SOUTHEAST THAN CURRENTLY PROGGED.
SAT STILL LOOKS TO BE THE WARMEST DAY OF THE PERIOD WITH A VIGOROUS
UPPER-LEVEL TROUGH LURKING OVER THE PACIFIC NW. THERMAL RIDGE AXIS
BUILDS INTO THE CWA WITH NAM H7 TEMPS INCREASING TO 13-14 C FROM THE
LARAMIE RANGE EASTWARD. MOST MOS GUIDANCE SUGGESTS HIGHS IN THE 83
TO 93 DEGREE RANGE OVER THE PLAINS...AND THIS LOOKS REASONABLE GIVEN
THE SYNOPTIC SETUP. THE PROGRESSION OF THE TROUGH AND ASSOCIATED SFC
COLD FRONT APPEARS A BIT SLOWER THAN EARLIER MODELS SUGGESTED...SO
THIS SHOULD DELAY PCPN CHANCES UNTIL MID TO LATE AFTN ON SAT. MIDLVL
QG FIELDS SHOW GOOD ASCENT SPREADING FROM WEST TO EAST AFTER 21Z ON
SAT. THIS OCCURS ALONG WITH LLVL CONVERGENCE ASSOCIATED WITH A
STRONG SFC COLD FRONT MOVING ACROSS THE CWA...SO AM CONFIDENT IN AT
LEAST SCATTERED COVERAGE OF SHOWERS AND TSTMS. INSTABILITY COULD BE
WANING BY THE TIME CONVECTION MOVES FAR ENOUGH EAST...BUT CAN NOT
RULE OUT A STRONG OR LOCALLY SEVERE STORM WITH NAM CAPES AROUND 1500
J/KG BENEATH STEEP MIDLVL LAPSE RATES AND ABOUT 30 KTS OF H5 FLOW.
IT WILL BE BREEZY ON SAT AFTN AND EARLY EVE...ESPECIALLY ALONG AND
WEST OF THE LARAMIE RANGE AS HEIGHT GRADIENTS INCREASE ALOFT AND A
STRONG SFC LOW MOVES ACROSS NORTHERN WY. WSW H7 WINDS AROUND 35 TO
40 KTS SUGGEST STRONGER WINDS OVER THE WIND PRONE AREAS...SO BUMPED
UP GUSTS TO AROUND 45 MPH AT ARL AND BRX.
SHOWERS WILL INCREASE OVERNIGHT THROUGH SUN AM...AND COULD CONTINUE
THROUGH MUCH OF THE AFTN WITH COLDER AIR ALOFT AS THE TROUGH MOVES
OVERHEAD. THE MODELS SHOW H7 TEMPS PLUNGING INTO THE MID SINGLE
DIGITS C ON SUN IN THE POST-FROPA AIR MASS. LOOKING FOR HIGHS TO BE
SOME 10 TO 15 DEGREES COOLER THAN SAT. FLOW ALOFT BRIEFLY BECOMES
MORE ZONAL BY LATE SUN NIGHT...WITH THE ECMWF FINALLY STARTING TO
BACK OFF ON QPF BY ABOUT 06Z MON.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 150 PM MDT FRI AUG 29 2014
SHORTWAVE TROUGH DRIVEN BY A 100+KT JET STREAK WILL SWEEP ACROSS
THE CWFA ON MONDAY. A QUICK SHOT OF MOISTURE ALONG WITH A WEAK
COLD FRONT WILL PRODUCE PERHAPS SOME AM SHOWER ACTIVITY ACROSS
CARBON AND CONVERSE COUNTIES. BETTER CONVECTIVE CHANCES WILL AWAIT
MONDAY AFTERNOON AS WEAK INSTABILITY IS REALIZED. PROGD SBCAPES
OF AROUND 500 J/KG SUGGEST THAT MOST OF THE CONVECTION WILL BE OF
THE WEAK VARIETY. HOWEVER WITH A STRONG JET OVERHEAD RESULTING IN
AROUND 50 KNOTS OF DEEP LAYER SHEAR...CANT ENTIRELY RULE OUT A FEW
STORMS BECOMING STRONG...ESPECIALLY OVR THE WRN NEBRASKA PANHANDLE
LATE IN THE AFTERNOON. CONVECTIVE CHANCES WILL COME TO AN END
QUICKLY MONDAY EVENING. A DRY ZONAL PATTERN WILL ENSUE ACROSS THE
INTERMOUNTAIN WEST BEHIND MONDAYS DEPARTING SHORTWAVE TROF. THIS
WILL BRING A DRY AND UNSEASONABLY WARM PERIOD INTO THE REGION. H7
TEMPERATURE PROGS INCREASE TO 14-16C...WHICH WILL YIELD DAILY HIGH
TEMPERATURES THAT WILL REACH THE 80S AND LOW 90S EAST OF THE
LARAMIE RANGE...WITH 70S OVR CARBON/ALBANY COUNTIES. THESE ABOVE
AVERAGE TEMPERATURES WILL COMBINE WITH BREEZY CONDITIONS AND AN
ALREADY DRY AIR MASS TO HEIGHTEN FIRE WEATHER CONCERNS WEDNESDAY
AND THURSDAY. LATEST MODEL GUIDANCE CONTINUES TO POINT TO EITHER
DEVELOPING ACROSS ACROSS THE PACNW OR PERHAPS A CUT-OFF JUST OFF
THE CALIFORNIA COAST LATE IN THE WEEK. IN EITHER CASE...SOUTHWEST
FLOW INTO THE ROCKYS WILL PROVIDE A FAVORABLE TRAJECTORY FOR
MOISTURE TO RETURN TO THE CWFA AS EARLY AS THURSDAY NIGHT...BUT
MORE SO FOR FRIDAY. TEMPERATURES WILL ALSO BE A TAD COOLER FRIDAY
AS A THICKER CLOUD CANOPY PREVENTS FULL INSOLATION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 1050 PM MDT FRI AUG 29 2014
ISOLATED THUNDERSTORMS CONTINUE ALONG THE WYOMING/COLORADO STATE
LINE WITH MOVEMENT TOWARDS THE SOUTHEAST. SHOULD NOT IMPACT ANY OF
OUR AIRPORTS THROUGH THE OVERNIGHT HOURS. VFR CONDITIONS EXPECTED
THROUGH THE OVERNIGHT AND MORNING HOURS WITH CONVECTION INCREASING
SATURDAY AFTERNOON. STILL TOO EARLY TO NAIL DOWN SPECIFIC TIMING
OF THUNDERSTORMS...SO JUST WENT WITH VCTS WORDING IN TAFS. LATER
SHIFTS CAN MORE ACCURATELY TIME THUNDERSTORMS...BUT LOOKS LIKE
MAYBE 21Z THROUGH 01Z OR SO FOR BEST COVERAGE.
&&
.FIRE WEATHER...
ISSUED AT 150 PM MDT FRI AUG 29 2014
NO CONCERNS FOR CRITICAL FIRE WEATHER IN THE NEAR FUTURE. A STRONG
WEATHER DISTURBANCE AND ASSOCIATED COLD FRONT WILL SWEEP ACROSS THE
AREA ON SAT AFTN THROUGH SUN MORNING. SHOWERS AND TSTMS WILL DEVELOP
FROM WEST TO EAST ACROSS SOUTHEAST WY AND THE WESTERN NE PANHANDLE
DURING THAT TIME. GUSTY WEST-TO-SOUTHWEST WINDS WILL OCCUR ALONG AND
WEST OF THE LARAMIE RANGE ON SAT WITH GUSTS OF 35 TO 45 MPH...BUT
MINIMUM RH VALUES SHOULD REMAIN ABOVE 20 PERCENT. COOLER ON SUN WITH
CONTINUED BREEZY CONDITIONS AND ISOLATED TO SCATTERED SHOWERS AND
WEAK TSTMS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...RUBIN
SHORT TERM...HAMMER
LONG TERM...HAHN
AVIATION...CLAYCOMB
FIRE WEATHER...HAMMER
AREA FORECAST DISCUSSION
NWS MIAMI FL
329 AM EDT MON SEP 1 2014
.HIGHLIGHTS...
* MODERATE RISK OF RIP CURRENTS ATLANTIC BEACHES
* SLIGHT TSTORM CHANCE EAST COAST, BETTER CHANCE GULF COAST TODAY
* STORMIER PATTERN MID-LATE WEEK; STRONG STORMS POSSIBLE
.DISCUSSION...
THE WEATHER PATTERN ON THIS LABOR DAY WILL REMAIN
MOSTLY UNCHANGED FROM YESTERDAY. RIDGE AXIS WILL REMAIN OVER NORTH
FLORIDA, MAINTAINING AN EASTERLY WIND FLOW LOCALLY WITH CONVECTIVE
FOCUS ALONG THE GULF COAST IN THE AFTERNOON. LOW LEVEL WINDS WILL
BE STRONG ENOUGH TO DISALLOW A FULL GULF SEA BREEZE FROM
DEVELOPING, BUT SOME VEERING OF THE WIND FIELD IS EXPECTEDTHERE
WHICH AGAIN WILL LEAD TO ENOUGH CONVERGENCE TO SPARK SOME TSTORM
DEVELOPMENT. ACROSS THE EAST COAST, HRRR SHOWS A SCENARIO SIMILAR
TO YESTERDAY WITH QUICK PASSING SHOWERS DEVELOPING. CANNOT RULE
OUT TSTORMS EAST COAST BUT CONVERGENCE WILL BE LACKING SO COVERAGE
WOULD BE ISOLATED AT BEST.
LIKE YESTERDAY, A LIMITING FACTOR FOR MORE ACTIVE TSTORMS IS THE
LACK OF A FULL FLEDGED ONSHORE GULF SEA BREEZE. HOWEVER, CANNOT
RULE OUT A STRONG TSTORM OR TWO GIVEN SOME CONVERGENCE ALONG WITH
THE INSTABILITY AND CONTINUED DRY AIR ALOFT. WIND GUSTS OF 40-50
MPH IS THE PRIMARY THREAT.
A DEEP LAYERED TROUGH EAST OF THE BAHAMAS IS SHOWN BY THE GLOBAL
MODELS TO MOVE WEST AND ACROSS SOUTH FLORIDA WED NIGHT-THU. THIS
WILL BE ASSOCIATED WITH COOLING ALOFT ALONG WITH INCREASING
MOISTURE, SPELLING A STORMIER PERIOD MID WEEK AND EVEN INTO LATE
WEEK AS HIGHER INSTABILITY REMAINS. POPS ACCORDINGLY SHOW AN
UPWARD TREND MID-LATE WEEK. COULD SEE SOME STRONG STORMS ANYWHERE
BEGINNING WED THROUGH LATE WEEK DUE TO THE COLD AIR ALOFT AND
TROUGH PASSAGE, THOUGH MORE CLOUDINESS WOULD BE A LIMITING FACTOR.
/GREGORIA
&&
.AVIATION...
HIGH PRESSURE WILL SLOWLY WEAKEN OVER THE SOUTHEASTERN UNITED
STATES TODAY WHICH IN TURN WILL KEEP A EASTERLY WIND FLOW OF
AROUND 5 KNOTS THROUGH EARLY THIS MORNING AT ALL OF THE TAF SITES.
THE WIND DIRECTION WILL REMAIN EASTERLY AFTER 14Z TODAY BUT
INCREASE TO AROUND 10 KNOTS OVER ALL OF THE TAF SITES.
THE WEATHER SHOULD REMAIN DRY THROUGH THE EARLY MORNING HOURS BEFORE
SOME SHOWERS WORKS INTO THE EAST COAST TAF SITES AFTER 14Z.
SO WILL PUT IN VCSH AFTER 14Z FOR THE EAST COAST TAF SITES. FOR
KAPF TAF SITE...THE WEATHER WILL ALSO REMAIN DRY THROUGH MOST OF
THIS LABOR DAY. HOWEVER...A LATE WEST COAST SEA BREEZE COULD
DEVELOP AND PUSH INTO THE KAPF TAF SITE AFTER 21Z TODAY. SO WILL
PUT IN VCTS BETWEEN 21Z AND 00Z TODAY.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS AT ALL
OF THE TAF SITES FOR THIS LABOR DAY.
&&
.MARINE...EAST SOUTHEAST WINDS LESS THAN 15 KT WILL PREVAIL AS
THE ATLANTIC RIDGE REMAINS NORTH OF THE LOCAL WATERS. SEAS WILL BE
CORRESPONDINGLY LOW. A TROUGH WILL MOVE ACROSS THE WATERS LATE
WED- THU, BRINGING AN INCREASING CHANCE OF THUNDERSTORMS
ESPECIALLY ACROSS THE ATLANTIC WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 79 90 77 / 30 20 40 20
FORT LAUDERDALE 91 80 90 80 / 30 20 50 20
MIAMI 90 80 89 78 / 30 20 50 20
NAPLES 91 76 91 76 / 60 30 60 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
SHORT TERM...57/DG
LONG TERM....57/DG
AVIATION...54/BNB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1247 AM CDT MON SEP 1 2014
.UPDATE...
ISSUED AT 820 PM CDT SUN AUG 31 2014
EVENING UPDATE FOR TIMING/INTENSITY OF THUNDERSTORMS INTO THE
FORECAST AREA LATE TONIGHT INTO MONDAY MORNING.
LATEST RADAR TRENDS...MODELED WELL BY THE HRRR/RAP...INDICATE
STORMS PUSHING INTO THE WESTERN FRINGE OF THE FORECAST AREA NEAR
AND AFTER 11 PM CDT. HAVE UPDATED FORECAST GRIDS TO ADJUST TIMING
AND BRING HIGHER POPS IN EARLIER. DESPITE THE COOLING BOUNDARY
LAYER...THE COMPLEX MOVING INTO CENTRAL IOWA MAY BE ABLE TO
SUSTAIN A DAMAGING WIND THREAT UNTIL 2 OR 3 AM CDT. CONVECTION
STILL EXPECTED TO WEAKEN OVERNIGHT AND DECREASE IN COVERAGE NEAR
AND EAST OF THE MISSISSIPPI RIVER. HAVE UPDATED THE HAZARDOUS
WEATHER OUTLOOK TO REFLECT FORECAST CHANGES.
&&
.SYNOPSIS...
ISSUED AT 313 PM CDT SUN AUG 31 2014
A WARM...MID SUMMER-LIKE DAY IS FOUND OVER OUR CWA TODAY AS WE
REMAIN WELL EAST OF THE COLD FRONT APPROACHING IOWA THIS AFTERNOON.
THE COLD FRONT IS SLOWLY MOVING EAST...AND HAS ALREADY SPAWNED A FEW
HIGH BASED THUNDERSTORMS FROM SOUTHERN MN TO FAR EASTERN NE.
TEMPERATURES WITH FULL SUN TODAY HAVE REACHED THE MID 80S AS OF 2
PM...AND APPEAR SET FOR HIGHS IN THE MID TO UPPER 80S BEFORE CLOUDS
INTERRUPT THE HEATING LATER THIS AFTERNOON. SURFACE BASED STORMS
REMAIN CAPPED FOR NOW...THOUGH CAPE VALUES ARE SHOWN ON RAP DATA TO BE
2000 TO 4000 J/KG.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 313 PM CDT SUN AUG 31 2014
THERE IS LITTLE DOUBT THERE WILL BE AN IMPRESSIVE CONVECTIVE EVENT
TONIGHT. THERE IS PLENTY OF DOUBT THAT IT WILL STRONGLY AFFECT MORE
THAN JUST THE WESTERN MOST PORTION OF OUR CWA. THE SLOW MOVING
FRONT SHOULD BE ENOUGH TO FOCUS STORMS WITH PLENTY OF CAPE AND
MOISTURE AVAILABLE TO THE WEST...LIKELY NEAR THE MISSOURI RIVER.
THEY SHOULD MOVE EAST...SLOWLY. THIS PLACES THE WEAKENING PHASE OF
THE COMPLEX INTO EASTERN IOWA BETWEEN MIDNIGHT AND 9 AM MONDAY. THIS
POOR DIURNAL TIMING COMBINED WITH LESS THAN IDEAL MOISTURE TRANSPORT
DURING THAT TIME FRAME SUGGESTS BOTH INTENSITY AND COVERAGE OF
STORMS WILL BE ON THE WANE IN THAT PERIOD. I HAVE CONFINED HIGH POPS
TO ONLY THE WESTERN CWA LATE TONIGHT...AND LOWERED TO CHANCE FOR
MONDAY MORNING SINCE MOST MODELS SUGGEST A FRAGMENTED LINE...AND
THAT SEEMS MOST LIKELY TO ME AS WELL. QPF SHOULD BE IMPRESSIVE TO
THE WEST...BUT MAY BE INSIGNIFICANT IN OUR CWA...GENERALLY 0.25 OR
LESS IN ALL BE THE FAR WEST...WHERE 0.5 TO 1.0 IS POSSIBLE.
MONDAY WILL SEE FAR BETTER DYNAMICS...THUS THE SPC OUTLOOK FOR
SEVERE WEATHER. HOWEVER...THE CONVERGENT OUTFLOW BOUNDARY WILL
LIKELY BE WELL IN ADVANCE OF THE COLD FRONT...WHICH SHOULD ALSO
DEFLECT THE STRONGEST HEATING WELL EAST OF THE CWA AS WELL.
THUS...THE WEAKENING CONVECTIVE DEBRIS SHOULD INHIBIT OUR MONDAY
SEVERE POTENTIAL...AS WELL AS WIDESPREAD RAIN POTENTIAL AGAIN. SURE
SEEMS THIS EVENT SHOULD PRODUCE THE MAJORITY OF ITS RAIN WEST AND
SOUTHEAST OF OUR CWA.
ERVIN
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 313 PM CDT SUN AUG 31 2014
THE FRONT WILL CLEAR THE SOUTHEAST HALF OF THE AREA LATE MONDAY
EVENING. THE SOUTHEAST HALF OF THE AREA SHOULD SEE PRECIPITATION
ONGOING AT SUNSET THAT ENDS FROM NORTHWEST TO SOUTHEAST AFTER
MIDNIGHT. DRIER AIR MOVING INTO THE AREA SHOULD RESULT IN LOWS NEAR
OR SLIGHTLY BELOW NORMAL BY SUNRISE TUESDAY.
TUESDAY/TUESDAY NIGHT DRY CONDITIONS ARE EXPECTED AS HIGH PRESSURE
MOVES THROUGH THE MIDWEST. TEMPERATURES SHOULD BE CLOSE TO NORMAL.
WEDNESDAY MORNING LOOKS TO BE DRY ACROSS THE AREA AS THE HIGH MOVES
TOWARD THE EAST COAST. A WEAK DISTURBANCE WILL MOVE THROUGH THE AREA
WEDNESDAY AFTERNOON. THE OVERALL FORCING IS NOT STRONG AND MOISTURE
AVAILABILITY IS IN QUESTION. IF PRECIPITATION DOES OCCUR IT WOULD BE
ISOLATED IN NATURE WITH THE SOUTH HALF BEING FAVORED.
WEDNESDAY NIGHT ON...
THE MODEL CONSENSUS HAS SLIGHT CHANCE TO CHANCE POPS IN EACH 12 HR
PERIOD FROM WEDNESDAY NIGHT THROUGH SATURDAY.
THERE IS A WEAK DISTURBANCE MOVING THROUGH THE AREA WEDNESDAY
NIGHT/THURSDAY. MOISTURE AVAILABILITY WILL BE ON THE INCREASE BUT
THE OVERALL FORCING IS NOT STRONG. THE POSSIBILITY DOES EXIST THERE
WILL BE PERIODS OF DRY WEATHER WEDNESDAY NIGHT/THURSDAY.
THE MODELS DIFFER SOMEWHAT ON THE TIMING BUT AGREE THAT ANOTHER COLD
FRONT WILL MOVE THROUGH THE AREA IN THE THURSDAY NIGHT THROUGH
FRIDAY NIGHT TIME FRAME.
SEVERAL MODELS ARE PUSHING A SIGNIFICANT HIGH INTO THE WESTERN GREAT
LAKES ON SATURDAY. THE CURRENT MODEL CONSENSUS HAS SLIGHT CHANCE
POPS ACROSS THE SOUTH QUARTER OF THE AREA BUT THE OVERALL TREND IS
SUGGESTING DECREASING PRECIPITATION CHANCES.
SATURDAY NIGHT THROUGH SUNDAY THE MODEL CONSENSUS HAS DRY CONDITIONS
WITH HIGH PRESSURE OVER THE GREAT LAKES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1237 AM CDT MON SEP 1 2014
LINEAR MESOSCALE CONVECTIVE SYSTEM WILL CONTINUE TO MOVE ACROSS THE
REGION OVERNIGHT WHILE SLOWLY WEAKENING. GUSTY WINDS WITH MVFR TO
LOCALLY IFR CONDITIONS EXPECTED IN THE STORMS... WITH AN ISOLATED
SEVERE WIND GUST TO 60 MPH POSSIBLE NEAR TO SOUTHWEST OF QUAD CITIES.
WAKE LOW FOLLOWING MAY RESULT IN GUSTY EAST/SOUTHEAST WINDS DEVELOPING
INTO EASTERN IA ESPECIALLY AT KCID TERMINAL. COLD FRONT ANTICIPATED
TO PASS THROUGH THE TERMINALS THIS AFTERNOON. REDEVELOPMENT OF SOME
SHOWERS AND STORMS IS POSSIBLE AHEAD OF THE FRONT FAVORING KMLI AND
KBRL...BUT NOT CONFIDENT TO INTRODUCE AT THIS TIME DUE TO POSSIBLE
LINGERING DEBRIS CLOUDS FROM AM CONVECTION AND WEAK FRONTAL CONVERGENCE.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...RP KINNEY
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...08
AVIATION...05
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1241 AM CDT Mon Sep 1 2014
.MESOSCALE DISCUSSION...
Issued at 1240 AM CDT MON SEP 1 2014
The midnight through 3 AM period will continue to see at least some
low end potential for marginally severe hail, and perhaps localized
damaging wind gusts in the strongest storms able to downburst and
transport momentum to the surface through the inversion (refer to
recent SPC mesoscale discussion for more details).
Aside from severe potential, the potential for flash flooding is
increasing and could see additional warnings needed during the
overnight hours. The outflow from the complex of storms has pushed
into southern Kansas and stretched west-to-east while the upper
trough and overall storm motion remains east southeast nearly
parallel to the effective boundary. Moisture transport is very
impressive into and over the frontal zone into central and east
central Kansas while precipitable water values are running 2 to 2.2
inches according to RAP analysis. Dual-pol signatures have at times
indicated very heavy rainfall rates to around 2" per hour with the
heaviest activity and spotters have reported 15-20 minute periods
with 1 to 1.5 inches of rain. The orientation of the front and storm
motion suggests training of individual convective updrafts over the
same areas from southern Dickinson through Morris, Lyon, Coffey,
Anderson, southern Osage and southern Franklin counties. Dual-pol
rain estimates as of midnight range from 4" in southern Dickinson
county to 2.5" in Lyon county to 2" in Osage/Franklin counties.
Given current trends and expectations, could end up seeing a broad
swatch of 2 to 5" with locally 6+ inches possible.
There are some indications that the rear edge of the convection is
beginning to forward propagate toward the southeast which may help
put a slightly faster end to the very heavy rain, but should
continue to see development in advance of the upper trough axis and
north of the outflow which could persist even behind any forward
propagating segments. This heavy precip is also falling across the
parts of the area that have been driest as of late, and can handle
more water. However, the torrential rates alone will produce
substantial runoff and may be sufficient for flash flooding even in
the dry conditions.
&&
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Monday)
Issued at 311 PM CDT SUN AUG 31 2014
Elevated activity has weakened and exited with good insolation in
recent hours in weak subsidence allowing for a quick increase in
winds and temps. 19Z surface observations suggest cold front from
south central Nebraska to the SW corner of Kansas with some CU
development on the north end. Recent water vapor imagery shows
main upper wave pushing through southern Wyoming with convection
in NC Colorado well behind the front.
Overall setup continues to support a rather wet next 12-18 hours
with cold front coming into northern and western areas overnight and
upper trough following, with low level jet ramping up to around
60kts. Nearby 12Z observed precipitable water values were at to just
above normal and continued advection of deeper moisture to the south
will pump these values up.
Still having some question on the early hours of the event. With
surface low pressure in far SE Colorado, convergence along the front
is not great, and the main upper trough well behind will not boost
convergence until perhaps the daytime hours of Labor Day. Various
higher resolution models are delayed with the convective initiation
until around 23-0Z and could occur well into the CWA. Dewpoint
depressions should remain in the 25-40F range for somewhat high
cloud bases, but increasing low level wind fields will support
strong low level helicity. Again, with the trough lagging, mid level
winds are somewhat low to support a long-lived supercell, and wind
and hail continue to the be the main severe weather concerns with ML
CAPE of 2000-2500 J/kg and downdraft CAPE around 1200 J/kg currently
analyzed. The high-res models are also similar with a secondary
impulse of convection moving through in the late evening to
overnight hours, perhaps via a sustained MCS from the current NC
Colorado storms. This could track over northern areas again and
bring an increased flooding concern, but with recent rains spotty at
best, am not confident enough for a Watch. Convection should overall
slowly clear from northwest to central areas overnight.
Cold front still appears to sag south into southern areas for the
afternoon hours of Labor Day. This again is not a clear-cut forecast
with convective activity possibly affecting the location of the
effective front. If at least some insolation can occur, cooling mid
levels behind the upper trough should allow for moderate instability
to again develop along and ahead of the effective front with plenty
of shear to support severe storms. This time, upper winds will be
stronger but weaker near the surface.
.LONG TERM...(Monday Night through Sunday)
Issued at 311 PM CDT SUN AUG 31 2014
For Monday night and Tuesday, have continued chances for precip as
the expected outflow boundary from tonight`s convection gets hung
up across southeast and south central KS. In general would anticipate
POPs diminishing and becoming increasingly confined to far
southern portions of the forecast area with time through the day
Tuesday as the upper forcing moves east of the area and the low
level jet veers to the southwest decreasing convergence along the
front.
Tuesday night may be more interesting in terms of strong to
possibly severe thunderstorms. Most model guidance is pointing to
strong theta-e advection overnight with good isentropic upglide.
Additionally model forecast soundings have fairly steep mid level
lapse rates with potentially 1000 to 1500 J/km of elevated
instability. The NAM also shows around 30 KTS of effective bulk
shear, so it is not out of the question that there could be some
elevated storms capable of producing large hail. This activity may
linger into Wednesday morning. After that the forecast is
expecting a dry period through Thursday before models bring a
frontal system into the area Thursday night through Friday night.
Because of this boundary, have continued with some chance POPs for
Thursday night through Friday. By Saturday, both the GFS and ECMWF
build a surface ridge into the central plains with dryer air
advecting in. Because of this, have trended POPs down for Saturday
and kept Sunday dry.
Temps are expected to remain warm through Thursday until the
frontal system enters the region with chances for rain. The
warmest days look to be Wednesday and Thursday as 850 temps warm
to around 25C. Therefore have highs in the mid 90s with lows
around 70 to the lower 70s. Temps should trend cooler by the
weekend due to cold air advection behind the front. May see lows
in the 50s with highs in the upper 70s to around 80 by Sunday.
&&
.AVIATION...(For the 06Z TAFs through 06Z Monday Night)
Issued at 1240 AM CDT MON SEP 1 2014
For the 06z TAFs, widespread showers and embedded thunderstorms will
persist through the overnight hours into Monday morning. Some models
are suggesting that areas of fog may develop before sunrise,
especially near KTOP/KFOE. There is still uncertainty with regards
to whether or not this will occur as winds may stay just high enough
to diminish this threat, but went ahead and added a TEMPO group at
this time and will continue to monitor the trends through the
overnight hours. Expect this precipitation to shift south of the TAF
sites during the morning hours with winds veering to the northwest
and eventually north-northeast with the frontal passage. There is a
chance for additional scattered thunderstorm develop late afternoon
into early evening. However, the TAF sites may be near the northern
edge of this precipitation development, so have only mentioned VCTS
at this time due to the uncertainty in the exact location of these
storms. Any storms that do develop near the TAF sites should shift
southward by mid to late evening.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...Barjenbruch
SHORT TERM...65
LONG TERM...Wolters
AVIATION...Hennecke
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
315 AM EDT Mon Sep 1 2014
.SHORT TERM (Now through Tuesday)...
Issued at 310 AM EDT Mon Sep 1 2014
A slow-moving cool front to our northwest will bring a noticeable
increase in southwesterly winds today, with gusts of 15 to 25 mph
likely this afternoon. First off though we may see some isolated
low-topped showers this morning, with convergence along a weak
low-level jet early this morning already initiating some in central
IN. HRRR indicates better coverage than what I`ll have in my
forecast, as current guidance coverage already is too high.
Cloud cover from the moist low levels and as additional moisture
streams into the region today in a deep southwesterly flow should
keep high temperatures from getting too far above normal, with
readings likely topping out in the mid to upper 80s. The focus for
storms this evening will be to our west and northwest, closer to the
approaching front. These storms may be able to get into our southern
Indiana counties around or after midnight.
There still are some uncertainties about how convective development
will occur from early to late Tuesday, as a lot will depend on the
evolution of these storms moving into our region. Should those
storms get in here more toward daybreak, then convective debris
could be enough to prevent furthern development during the day
Tuesday, despite relatively high precipitable waters. Should those
storms die off overnight and leave boundaries behind, Tuesday could
become more active with heating. Will leave in likely pops for the
day Tuesday, as would lean more towards the latter solution that
we`ll see a few breaks in the clouds to generate more storms.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Sep 01 2014
Tuesday Night and Wednesday...
Surface high pressure will slide over the Ohio Valley behind the
nearly washed out front to our south on Tuesday night. An isolated
shower or storm could linger into the evening hours across the south
or east CWA, otherwise expect a dry and slightly cooler night. Lows
should drop into the upper 60s and around 70. Isolated or widely
scattered diurnally driven showers/storms are expected to be
possible across southern KY on Wednesday. Most areas will stay dry
with mostly sunny skies and highs in the 85 to 88 degree range.
Wednesday Night - Friday...
The southern CONUS upper ridge will build over the area to end the
week, however this will not be enough to suppress diurnally
driven convection each afternoon and early evening. Will continue
mention of isolated to widely scattered coverage on Thursday, with
better coverage on Friday more solidly in the scattered range. Along
with this ridge, the heat and humidity will return with highs in the
upper 80s to around 90 each day. With dew points in the low 70s each
day, conditions will feel quite muggy. The environment should become
pretty unstable each afternoon/evening, however the lack of deep
layer flow will keep any convection pulse in nature. Lows by
Thursday night will be back in the low 70s.
Friday Night - Saturday Night...
The upper ridge will be suppressed southward to start the weekend, as
a wave skirts along the eastern US/Canada border. This will drag a
stronger cold front toward our moist and unstable airmass, keeping
scattered storms in play on Friday night. Saturday should bring the
best chance of storms for the whole forecast period as the front
tries to slide through. Have gone with 40-50% coverage. With
slightly better deep layer flow over the area, the threat for a few
stronger storms seems reasonable. Biggest concern would be gusty
winds, along with cloud to ground lightning and brief heavy
rainfall. A few storms could linger in our south and east Saturday
evening.
Expect more mild lows on Friday night with the mercury only dropping
to the low 70s. Highs on Saturday will be dependent on convection
and where the frontal boundary resides, but it looks like temps will
max out around 80 north, to the mid or upper 80s south. Lows
Saturday night will be cooler on the north side of the boundary.
Look for readings in the 60s.
Sunday...
Surface high pressure takes back over on Sunday, bringing dry and
cooler conditions to start the new work week. Look for highs in the
upper 70s and low 80s, with lows Sunday night expected to be in the
upper 50s and low 60s!
&&
.AVIATION (06Z TAF Update)...
Issued at 120 AM EDT Mon Sep 1 2014
Have some mid-level drying out their now, helping to rid the region
of showers/storms for now, but not necessarily lower-level issues.
Each of the terminals may see some periods of MVFR clouds through
daybreak. Then we will see winds pick up from the southwest, ahead
of a cold front approaching from the northwest. Gusts of 20-25 knots
are possible through the day. An isolated pop-up storm is possible
in the afternoon, but not confident enough to put in the forecast at
this time. The better chance for rain will come Tuesday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Short Term........RJS
Long Term.........BJS
Aviation..........RJS
AREA FORECAST DISCUSSION
NWS GRAY ME
1240 AM EDT MON SEP 1 2014
.SYNOPSIS...
A COLD FRONT WILL DROP SOUTHEAST THROUGH THE REGION O0VERNIGHT
AND WILL STALL OFF THE COAST ON MONDAY. A SECOND COLD FRONT WILL
APPROACH FROM THE WEST ON TUESDAY AND WILL CROSS THE REGION
TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST ON
WEDNESDAY AND WILL CREST OVER THE REGION THURSDAY BEFORE SHIFTING
OFFSHORE. HIGH PRESSURE WILL HOLD OFF THE NEW ENGLAND COAST ON
FRIDAY. A COLD FRONT WILL CROSS THE AREA ON SATURDAY.
&&
.NEAR TERM /THROUGH TODAY/...
UPDATE...
HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS. SOAKING RAINS
IN THE PORTLAND AREA HAVE SHIFTED EAST AND INTO THE GULF OF MAINE
EARLY THIS MORNING. IN ITS WAKE...PLENTY OF FOG WILL DEVELOP WITH
LOW LEVEL MOISTURE IN PLACE AND CLEARING SKIES. MODIFIED CLOUD AND
DEW POINT GRIDS...OTHERWISE...NO SIGNIFICANT CHANGES THIS HOUR.
PREV DISC...
SHOWERS AND EMBEDDED TSTMS CONTINUE TO SLOWLY MOVE EWD ACROSS THE
SRN PART OF THE FORECAST AREA. IN A LINE FROM JUST E OF KCON TO
KPWM RAIN IS HEAVY AT TIMES...WITH OCNL RATES IN EXCESS OF 3
INCHES/HR. BACK EDGE IS QUICKLY APPROACHING THE COAST...THOUGH
HEAVIEST RATES WILL LINGER WITHIN THIS LINE. TO EITHER SIDE OF
THAT LINE...A LIGHTER RAIN WILL CONTINUE TO FALL FOR THE NEXT
COUPLE OF HOURS. HAVE ADJUSTED POP BASED ON RADAR TREND AND LATEST
HI-RES MODEL GUIDANCE. SHOULD BE A MOSTLY DRY NIGHT ONCE THIS RNFL
CLEARS THE COAST...EXCEPT FOR THE FAR NRN ZONES WHERE LINGERING
CONVECTION ASSOCIATED WITH LEADING EDGE OF S/WV TROF MAY HOLD
TOGETHER.
PREVIOUS DISCUSSION...A SHORT WAVE TROUGH APPROACHING FROM THE
WEST WILL WEAKEN THIS EVENING AS IT MOVES EASTWARD TOWARD NORTHERN
NEW ENGLAND. THE ATTENDANT SFC COLD FRONT WILL APPROACH AS
WELL...AND ALSO WEAKEN. A SHIELD OF LIGHT RAIN CONTINUES TO
TRAVERSE ACROSS NORTHERN AND CENTRAL ZONES AS OF 19Z THIS SUNDAY
AFTERNOON. THIS WILL STABILIZE THE AIRMASS ACROSS THIS AREA.
HOWEVER...ALONG THE COASTAL PLAIN SWWD OVER TO SOUTHERNMOST NH
SHOULD REMAIN MOSTLY DRY FOR THE NEXT SEVERAL HOURS.
THEREFORE...THESE AREAS SHOULD RETAIN THE INSTABILITY /1000-1500
J/KG SBCAPE/ THROUGH EARLY EVENING. THE QUESTION IS DO
THUNDERSTORMS DEVELOP IN THIS AREA.
SEVERAL OF THE LATEST RUNS OF THE HRRR CONTINUE TO SHOW
THUNDERSTORMS WILL HEAVY RAINFALL MOVING ACROSS SOUTHERNMOST NH
AND SOUTHERNMOST ME BETWEEN 22Z AND 03Z. THIS SEEMS REASONABLE
GIVEN THE CURRENT MESOSCALE SETUP. AS A RESULT WILL CONTINUE WITH
HIGH POPS...ESPECIALLY IN THIS AREA. MODERATE DEEP LAYER SHEAR MAY
AID IN A FEW OF THESE STORMS BECOMING STRONG...WITH GUSTY WINDS
BEING THE MAIN THREAT. WITH PWATS INCREASING TO AROUND 2 INCHES BY
EARLY EVENING...TORRENTIAL DOWNPOURS WILL BE LIKELY IN ANY
THUNDERSTORM. THERE IS A LOW PROB FOR TRAINING STORMS ACROSS
SOUTHERN NH AND SOUTHERNMOST ME...SO LOCALIZED FLASH FLOODING WILL
BE POSSIBLE THIS EVENING. THE BULK OF THE ACTIVITY SHOULD MOVE
OFFSHORE AROUND MIDNIGHT LEADING TO A MAINLY DRY OVERNIGHT.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
ON MONDAY...THE SHORT WAVE TROUGH WILL DEPART IN THE MORNING.
STILL...WITH MODERATE AMOUNTS OF LOW LEVEL THETA-E IN TANDEM WITH
SLIGHTLY COOLER TEMPS ALOFT AND A WEAK SFC FRONT IN THE VCNTY...WE
COULD SEE A FEW SHOWERS DURING THE DAY...PERHAPS A THUNDERSTORM.
HOWEVER...ACTIVITY SHOULD BE FEW AND FAR BETWEEN...WITH HIGHEST
POPS ACROSS CENTRAL AND NORTHERN ZONES. HUMID CONDITIONS WILL
CONTINUE.
MUGGY AND QUIET MONDAY NIGHT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
COLD FRONT APPROACHES FROM THE WEST ON TUESDAY AND WILL
SET THE STAGE FOR POSSIBLE SEVERE WEATHER. PRE-FRONTAL
TROUGH FORECAST TO PUSH IN FROM THE WEST DURING PRIME TIME
HEATING. MODERATE CAPES AND INCREASING SHEAR DURING THE
AFTERNOON AND EVENING HOURS WILL LIKELY RESULT IN MORE
ORGANIZED CONVECTION DURING THE LATE AFTERNOON AND EVENING WITH
DAMAGING WINDS THE MAIN THREAT. STRONGER CELLS MAY ALSO PRODUCE
SOME HAIL BUT FREEZING LEVELS WILL BE QUITE HIGH SO NOT LOOKING
FOR MUCH IN THE WAY OF SEVERE HAIL. WILL SEE A HOT AND MUGGY DAY
WITH HIGHS RANGING THROUGH THE 80S.
COLD FRONT WILL PUSH OFFSHORE TUESDAY NIGHT WITH CONVECTION ENDING
ACROSS THE REGION BY MIDNIGHT. HIGH PRESSURE BUILDING IN FROM THE
WEST WILL BRING CLEARING DOWNWIND OF THE MOUNTAINS. LOW TEMPS
OVERNIGHT WILL RANGE THROUGH THE 60S.
COOLER AND MUCH DRIER AIR PUSHES IN FOR WEDNESDAY AS HIGH PRESSURE
CONTINUES TO BUILD INTO THE NORTHEAST. SHOULD SEE A MOSTLY SUNNY
DAY WITH HIGHS FROM THE MID 70S TO LOWER 80S.
FAIR WEATHER WILL CONTINUE THURSDAY AND FRIDAY AS HIGH PRESSURE
CONTINUES TO BUILD SOUTH OF THE REGION FINALLY PUSHING OFFSHORE
ON FRIDAY. AFTER A STELLAR LATE SUMMER DAY ON THURSDAY...RETURN
FLOW WILL BEGIN TO PUMP WARMER AND MORE HUMID AIR BACK INTO THE
REGION ON FRIDAY. MAY SEE ENOUGH INSTABILITY CREEP INTO THE
CONNECTICUT VALLEY LATE FRIDAY TO KICK OFF AN ISOLATED SHOWER OR
THUNDERSTORM BUT THE MAJORITY OF THE FORECAST AREA WILL SEE A DRY
DAY.
RATHER STRONG LOOKING COLD FRONT FORECAST TO PUSH IN FROM THE WEST
ON SATURDAY WHICH COULD PRODUCE ANOTHER ROUND OF SEVERE
THUNDERSTORMS.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
.SHORT TERM...LOCAL IFR IN SHOWERS AND THUNDERSTORMS THIS
EVENING. AFTER MIDNIGHT...FOG AND SOME LOW STRATUS MAY DEVELOP AND
RESULT IN LOW CONDITIONS AS WELL. MAINLY VFR EXPECTED ON MONDAY
OUTSIDE OF WDLY SCT SHOWERS.
.LONG TERM...MAINLY VFR EXPECTED OUTSIDE OF ANY SHOWERS AND
THUNDERSTORMS TUE EVE/NIGHT. SOME VALLEY FOG AND COASTAL STRATUS
POSSIBLE DURING THE PERIOD LATE AT NIGHT.
&&
.MARINE...
.SHORT TERM...HAVE DROPPED THE SCAS FOR TONIGHT.
.LONG TERM...SUB-SCA EXPECTED TUE THROUGH FRI.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
515 AM EDT MON SEP 1 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT MON SEP 1 2014
WV IMAGERY AND RUC INDICATED A BROAD MID/UPPER LEVEL TROUGH FROM THE
ROCKIES INTO THE NRN/CNTRL PLAINS. AT THE SFC...A COLD FRONT
EXTENDED FROM NEAR INL THROUGH CNTRL MN INTO NW IA. A WEAK SHRTWV
FROM NE MN INTO NW WI SUPPORTED AN AREA OF SHOWERS AND ISOLD TSRA
OVER ERN MN INTO NW WI AND LAKE SUPERIOR. A STRONGER SHRTWV WAS
LOCATED OVER SW MN INTO NW IA. WITH ONLY MODEST 500-1000 J/KG
MUCAPE...ONLY A FEW TSRA WERE NOTED OVER THE REGION. THE MORE ACTIVE
CONVECTION OVER ERN LAKE SUPERIOR WAS ASSOCIATED WITH AN AREA OF
STRONGER 850 THETA-E ADVECTION AT THE NOSE OF THE LLJ.
TODAY...AS THE NW IA SHRTWV LIFTS TOWARD THE AREA WITH MODERATE
700-300 MB QVECTOR CONV AND THE COLD FRONT APPROACHES THE
AREA...EXPECT SHRA/TSRA COVERAGE TO INCREASE THIS MORNING. EVEN WITH
0-1KM/0-6KM SHEAR AROUND 40 KNOTS...SINCE INSTABILITY WILL REMAIN
LIMITED...MAINLY JUST BRIEF HEAVY RAIN IS EXPECTED. OVERALL RAINFALL
AMOUNTS SHOULD BE LIMITED GIVEN THE QUICK MOVEMENT OF THE CONVECTIVE
CELLS AND LACK OF LARGE SCALE ORGANIZATION. THE PCPN WILL DIMINISH
FROM WEST TO EAST THIS AFTERNOON AS THE COLD FRONT MOVES THROUGH AND
QVECTOR DIV SPREADS INTO UPPER MI IN THE WAKE OF THE SHRTWV. CLOUD
COVER WILL KEEP HIGH TEMPS NEAR OR SLIGHTLY BELOW SEASONAL AVERAGES
IN THE UPPER 60S TO AROUND 70.
TONIGHT...ANY LINGERING PCPN OVER THE ERN CWA IN THE EVENING WILL
END EARLY. OTHERWISE...A DRIER AIRMASS MOVING INTO THE AREA WITH
DEWPOINTS DROPPING TOWARD THE LOWER 50S WILL ALLOW TEMPS TO ALSO
DROP INTO THE LOWER TO MID 50S AS SKIES PARTIALLY CLEAR. AN INCREASE
IN CLOUD COVER IS EXPECTED LATE OVER THE SW CWA AHEAD OF THE NEXT
WEAK SHRTWV.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 321 AM EDT MON SEP 1 2014
IN THE WAKE OF STRONGER SHORTWAVE AND SFC FRONT MOVING THROUGH
TODAY...ANOTHER SHORTWAVE CLIPS ACROSS THE AREA ON TUESDAY IN
INCREASINGLY ZONAL FLOW ALOFT. MOISTURE IS LIMITED WITH THE WAVE AS
SOUNDINGS ONLY SHOW MOISTURE H8-H7. PRETTY HIGH BASED SHRA AND WILL
ALSO MENTION ISOLD TSRA WITH MLCAPE 500-1000 J/KG PER ECMWF AND GFS.
WILL INCLUDE SLIGHT CHANCE POPS. A LULL FOR TUE NIGHT AS SFC RIDGE
MOVES FROM MIDDLE MISSISSIPPI RIVER VALLEY TO THE OHIO VALLEY. LGT
SW WINDS ON PERIFERY OF THE RIDGE WILL LIMIT COOLING. LOWEST PWAT
FAR EAST CWA WHERE MIN TEMPS MAY FALL TO AROUND 50 DEGREES. ON
WEDNESDAY...GFS AND GEM-NH INDICATE SOME SHOWERS COULD OCCUR IN THE
AFTN OVER MAINLY THE WEST HALF CWA. WEAK SHORTWAVE IS THERE BUT ONLY
APPEARS THAT BEST MOISTURE INFLOW IS OVER FAR WEST CWA. WARM AIR
ADVECTION BOOSTS H85 TEMPS TO AROUND +15C SO AS LONG AS SKIES STAY
AT LEAST PARTLY CLOUDY...MAX TEMPS WILL TOP OUT IN THE MID 70S TO
LOWER 80S.
LATER WEDNESDAY NIGHT INTO THURSDAY MORNING LARGER SCALE LIFT
AHEAD OF UPPER TROUGH INCREASES OVER NORTHERN PLAINS AND WESTERN
GREAT LAKES. LIKELY WILL BE SOME SHORTWAVES SLIDING OUT OF NORTHERN
PLAINS AS WELL...THOUGH RIGHT NOW SIGNAL OF ANY STRONGER SHORTWAVE
IS MINIMAL. THERE IS A MID LEVEL JET MAX SLIDING OVER THE AREA AND
H85-H5 Q-VECTOR CONVERGENCE WILL BE ON THE INCREASE. PRIMARY SFC
TROUGH WILL BE OVER MINNESOTA AND BASED ON SFC WINDS AND
DWPNTS...THERE WILL BE A WARM FRONT VCNTY OF SOUTHERN/CENTRAL
MINNESOTA INTO WESTERN WISCONSIN. BULGE OF WARMTH ALOFT RESULTS IN
AN ELEVATED MIXED LAYER WITH H7-H5 LAPSE RATES OVER 8C/KM MAKING IT
OVER UPR LAKES AHEAD OF THE SFC TROUGH. RESERVOIR OF ML MUCAPE OVER
2000J/KG WILL BE JUST SOUTHWEST OF UPR MICHIGAN WITH MID LEVEL FLOW
SW-NE. EDGE OF SFC BASED CAPE AND ORIENTATION OF H85-H3 THICKNESSES
INDICATE THAT STRONGER STORMS MAY BE MORE TO SOUTHWEST OF UPR
MICHIGAN LATER WEDNESDAY NIGHT INTO THURSDAY MORNING. TOUGH TO SAY
AT THIS POINT THOUGH. CONSENSUS CHANCE POPS WORK FOR NOW SINCE THERE
WILL BE LARGE SCALE WARM AIR ADVECTION AND H85-H7 MOISTURE TRANSPORT
AIMED INTO THE AREA. MORE SHRA/TSRA POSSIBLE AS SFC FRONT WORKS
ACROSS UPR MICHIGAN LATER ON THURSDAY. PLENTY OF INSTABILITY AS
TEMPS IN THE SOUTH-SOUTHWEST FLOW AHEAD OF FRONT SHOULD REACH TOWARD
80 DEGREES WITH EVEN A FEW HOURS OF PARTIAL CLEARING SINCE H85 TEMPS
ARE 18-20C. MOISTURE AVAILABILITY/MID LEVEL CAPPING ALONG THE FRONT
REMAINS A CONCERN FOR COVERAGE OF SFC BASED STORMS IN THE AFTN. MODELS
MAY BE PICKING UP ON THIS AS GFS/ECMWF SHOW A MIN IN QPF 18Z-24Z BUT
THEN INCREASE IT BY 06Z ON FRIDAY AS FRONT WILL MAINLY BE SOUTH AND
EAST OF CWA BY THAT TIME. NO NEED TO GET TOO FANCY WITH THE GRIDS
ATTM GIVEN ALL THE UNCERTAINTY. KEPT WITH THE CONSENSUS CHANCE POPS
ON THURSDAY WITH THIS DROPPING OFF TO LOWER CHANCES THURSDAY NIGHT
CLOSER TO THE DEPARTING FRONT.
REST OF THE FORECAST LOOKS DRY AND COOLER AS HIGH PRESSURE BUILDS IN
ON FRIDAY AND WILL HOLD ON THROUGH NEXT WEEKEND. MAX TEMPS IN THE
MID 60S TO LOWER 70S. CHILLY LOWS POSSIBLE INLAND BOTH FRIDAY NIGHT
AND SATURDAY NIGHT DUE TO THE DRY AIRMASS AND LGT WINDS BENEATH THE
HIGH PRESSURE. BIAS CORRECTED GUIDANCES SHOWED MINS IN THE LOWER 40S
BUT WOULD NOT BE SURPRISED TO SEE READINGS DIPPING INTO THE 30S
EITHER OF THOSE NIGHTS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 132 AM EDT MON SEP 1 2014
IWD...LLWS AND NMRS HEAVY SHRA WITH SOME EMBEDDED TS RIDING NNEWD
UNDER A STRONG SSW LLJ IN ADVANCE OF A SLOW MOVING COLD FNT WILL
IMPACT THIS SITE THRU SUNRISE. ALTHOUGH THERE MAY BE SOME BREAKS IN
THE HEAVIER SHRA...MVFR CONDITIONS WL PREDOMINATE. THE CIGS ARE
LIKELY TO FALL INTO THE IFR RANGE BRIEFLY DURING MID MRNG AS THE FNT
PASSES AND THE WIND SHIFTS TO AN UPSLOPE WNW DIRECTION. THE W WIND
BEHIND THE FROPA WL TAP DRIER AIR AND ALLOW FOR CONDITIONS TO
IMPROVE TO VFR DURING THE AFTN.
CMX...VFR CONDITIONS WL DOMINATE EARLY IN THE TAF PERIOD BUT THEN
GIVE WAY TO MVFR WX AS A BAND OF MDT-HVY SHRA AHEAD OF THE SLOWLY
APRCHG COLD FNT EDGES SLOWLY TO THE E. LLWS WL BE THE RULE THRU
SUNRISE UNDER A STRONG SW LLJ. A WSHFT TO AN UPSLOPE W DIRECTION
BEHIND THE FROPA AND WITH SOME CONTINUED -SHRA WL RESULT IN A PERIOD
OF IFR CONDITIONS DURING THE LATE MRNG/EARLY AFTN BEFORE THE W WIND
TAPS DRIER AIR AND RESULTS IN IMPROVEMENT TO VFR BY LATE IN THE DAY.
SAW...EXPECT LO CLDS/IFR CIGS TO LINGER THRU THE NGT WITH A MOIST
SLY FLOW UNDER A STRONG SW LLJ SUFFICIENT TO CAUSE LLWS DRAWING LLVL
MSTR N FM LK MI IN THE PRESENCE OF DIURNAL COOLING. EXPECT SOME SHRA
WITH MVFR CONDITIONS TO DVLP BY LATE MRNG WITH THE CLOSER APRCH OF
SFC COLD FNT. EXPECT IMPROVEMENT LATE IN THE AFTN WITH A WSHFT TO A
DOWNSLOPE W DIRECTION AND ARRIVAL OF DRIER AIR FOLLOWING THE FROPA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT MON SEP 1 2014
WINDS WILL BE 20 KNOTS OR LESS THROUGH THIS FORECAST PERIOD WITH
AREAS OF FOG PERSISTING UNTIL DRIER AIR MOVES INTO THE REGION
TONIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
149 AM EDT MON SEP 1 2014
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 322 PM EDT SUN AUG 31 2014
A WEAK AREA OF HIGH PRESSURE WILL KEEP MUCH OF THE REGION DRY INTO
THE EVENING. A COLD FRONT WILL APPROACH FROM THE WEST ON LABOR DAY
TRIGGERING SHOWERS AND THUNDERSTORMS. HIGH PRESSURE WILL RETURN
FOR TUESDAY DRYING THE REGION OUT.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 322 PM EDT SUN AUG 31 2014
THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE POTENTIAL FOR
SEVERE WEATHER ON MONDAY. OVERALL THE POTENTIAL STILL EXISTS.
ONE POTENTIAL LIMITING FACTOR WILL BE WHAT IMPACTS THE DECAYING
AREA OF THUNDERSTORMS WILL HAVE AS IT MOVES IN FROM THE WEST
MONDAY MORNING. THE HRRR RUC SHOWS THIS SYSTEM WEAKENING WELL
BEFORE IT ARRIVES IN MI...SO I AM THINKING THIS WILL HAVE A
MINIMAL IMPACT ON THE POTENTIAL INSTABILITY MONDAY. THE
COMBINATION OF HEATING AND MOISTURE ADVECTION SUPPORTS CAPE OVER
1500 J/KG ON MONDAY. DEEP LAYER SHEAR INCREASES TOWARD 18Z AS THE
MID LEVEL WAVE CURRENTLY IN WI ARRIVES IN NW LOWER. THE LIFT
ASSOCIATED WITH THIS FEATURE SHOULD TRIGGER STORMS. THE SHEAR WILL
HELP TO INCREASE THE POTENTIAL FOR ORGANIZED CONVECTION AND
RESULTING SEVERE WEATHER. DAMAGING WINDS AND LARGE HAIL A THREAT.
SRH VALUES AROUND 200 M2/S2 DO SUPPORT A RISK FOR TORNADOES.
.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 322 PM EDT SUN AUG 31 2014
MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT INTO NEXT WEEKEND...
HOWEVER THERE ARE TIMING DIFFERENCES WITH A STRONG COLD FRONT THAT
COMES THROUGH FRIDAY/FRIDAY NIGHT.
LARGE HIGH PRESSURE IS EXPECTED TO BE SITTING OVER THE EAST SEABOARD
BY MID WEEK. THIS WILL BRING WARMING SOUTHERLY FLOW TO THE GREAT
LAKES REGION. IT CONTINUES TO LOOK LIKE THURSDAY WILL BE THE
WARMEST DAY OF THE WEEK WITH 80S FOR HIGHS. THE RISK FOR SHOWERS
AND STORMS WILL INCREASE ON THURSDAY WITH A COLD FRONT MOVING INTO
THE WESTERN GREAT LAKES. WARM AND MOIST AIR WITH MOVE IN AHEAD OF
THIS FRONT. IF A LOW LEVEL JET COMES INTO PLAY WE COULD BE LOOKING
AT STRONG TO SEVERE STORMS TOWARD THE END OF THE DAY.
THERE CONTINUES TO BE TIMING DIFFERENCES WITH THE FRONT...BUT THE
GFS SLOWED THE FRONT DOWN...CLOSER TO THE WHAT THE ECMWF HAS SHOWN.
THEREFORE BELIEVE THE FRONT WILL BE COMING THROUGH ON FRIDAY WITH
ADDITIONAL CHANCES FOR SHOWERS AND STORMS. MUCH COOLER AIR FOLLOWS
THIS STRONG FRONT FOR FRIDAY NIGHT AND INTO NEXT WEEKEND. H8 TEMPS
DROP TO +7 TO +10C AS COMPARED TO AROUND +19C AHEAD OF THE COLD
FRONT. THE WEEKEND SHOULD FEATURE HIGHS IN THE UPPER 60S TO MID 70S
WITH MAINLY DRY WEATHER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 149 AM EDT MON SEP 1 2014
THERE ARE A FEW ITEMS THAT COULD IMPACT AVIATION OPERATIONS OVER
THE NEXT 24 HOURS ACROSS SW LOWER MI. THE FIRST ITEM IS FOG
POTENTIAL. A DECENT AMOUNT OF LOW LEVEL MOISTURE REMAINS IN
PLACE THIS MORNING AND TEMPS AND DEW POINTS ARE CLOSE ALREADY. THE
BEST CHC FOR FOG AND SOME POSSIBLE STRATUS WILL BE ALONG AND SE OF
I-69 WHERE A FEW SHOWERS WERE PRESENT EARLIER AND WHERE THE
MOISTURE HAS HUNG IN THE MOST. CAN NOT RULE OUT SOME NEAR KGRR AND
KAZO...BUT THE FURTHER WEST THE WINDS WILL REMAIN UP AND LIMIT FOG POTENTIAL.
THE NEXT THING IS THE POTENTIAL FOR PCPN TODAY. MOST DATA
INDICATES THAT WHATEVER IS LEFT OF THE LINE OF SHOWERS/STORMS NEAR
THE MISSISSIPPI RIVER AS OF 0545Z WILL MOVE INTO THE AREA
TOWARD 15Z OR SO. IT WILL INITIALLY FALL APART WITH LESS CHC OF
IMPACTS FROM IT TOWARD THE LAKESHORE. AS IT ENCOUNTERS SOME
DIURNAL INSTABILITY TOWARD THE EAST...WE EXPECT IT TO REINTENSIFY
INTO A LINE OF STORMS BY THE TIME IT REACHES U.S.-127 BY 19Z OR
SO. BEST CHC FOR LOWER CONDITIONS WILL BE ACROSS THE EAST WHERE
IFR WOULD BE LIKELY IN HEAVY RAINFALL. THIS CAN BE FINE TUNED
CLOSER TO THE EVENT.
ONCE THE LINE OF STORMS MOVES EAST...THERE SHOULD BE SOMEWHAT OF A
BREAK. ANOTHER PERIOD OF SOME SHOWERS WILL BE POSSIBLE WITH THE
WAVE TOWARD 00Z AND AFTER THAT.
&&
.MARINE...
ISSUED AT 322 PM EDT SUN AUG 31 2014
BEACH HAZARDS AND SCA ISSUED FOR MONDAY
&&
.HYDROLOGY...
ISSUED AT 322 PM EDT SUN AUG 31 2014
HIGH PWAT VALUES SUPPORT LOCALLY HEAVY RAIN ON MONDAY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT FROM 10 AM EDT THIS MORNING THROUGH THIS
EVENING FOR MIZ037-043-050-056-064-071.
LM...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EDT THIS
EVENING FOR LMZ844>849.
&&
$$
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...JK
AVIATION...NJJ
HYDROLOGY...MJS
MARINE...MJS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
447 AM CDT MON SEP 1 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT MON SEP 1 2014
A FAIRLY BROAD LONGWAVE TROUGH WAS SETTING UP THIS MORNING FROM THE
GREAT LAKES BACK TO THE PAC NW. THE MAIN PIECE OF ENERGY EMBEDDED
WITHIN THIS TROUGH IS THE TROUGH WORKING INTO WRN IA/SRN MN THIS
MORNING. THERE IS A FAIRLY POTENT SHORTWAVE WITHIN THIS TROUGH NEAR
SIOUX FALLS...AS EVIDENCE BY THE NICE SPIN SEEN WITHIN THE KFSD
REFLECTIVITY. AT THE SFC...A BROAD FRONTAL TROUGH WAS SITUATED
ACROSS MN...THOUGH THE WIND SHIFT AND T/TD DROP YOU COULD ASSOCIATE
WITH THE MAIN FRONT WAS SITUATED FROM ABOUT CANBY UP TO
INTERNATIONAL FALLS. 8Z SPC MESO ANALYSIS STILL SHOWED ABOUT 500
J/KG OF SBCAPE OUT AHEAD OF THIS BOUNDARY. THIS INSTABILITY COMBINED
WITH LIFT FROM THE WAVE NEAR SIOUX FALLS EXPLAINS WHY WE HAVE
CONTINUED TO SEE NEW CONVECTION DEVELOP THROUGH THE NIGHT OUT IN WRN
MN. ALTHOUGH NONE OF THE CAMS HAVE HANDLED THIS TRAILING ACTIVITY
WELL...THE LOCAL WRF HAS HANDLED IT THE BEST THIS MORNING...SO
FOLLOWED IT FOR SLOWLY DRAGGING POPS ACROSS THE AREA THIS MORNING.
LOOKS LIKE IT WILL TAKE UNTIL BETWEEN 15 AND 18Z TO COMPLETELY CLEAR
THIS ACTIVITY OUT OF WRN WI. DUE TO LIMITED INSTABILITY...THE SEVERE
POTENTIAL WITH THIS ACTIVITY WILL ESSENTIALLY BE NIL...BUT WE WILL
CONTINUE TO SEE HEAVY DOWNPOURS...WITH A QUICK HALF TO ONE INCH OF
RAIN LIKELY FOR AREAS THAT GET UNDER HEAVIER RAIN CORES.
BEHIND THIS SYSTEM SKIES WILL CLEAR OUT FOR A BIT...BUT BY THE
AFTERNOON...TROUGH AXIS CURRENTLY SITUATED FROM SASKATCHEWAN DOWN
INTO ERN IDAHO WILL BE SPREADING MID CLOUDS INTO WRN MN AS IT
QUICKLY TRACKS ACROSS THE DAKOTAS WITHIN A MODERATELY FAST ZONAL
FLOW. WILL LIKELY SEE SOME SCATTERED DIURNALLY DRIVEN ACTIVITY
DEVELOP ACROSS THE DAKOTAS AHEAD OF THE WAVE THAT WILL MAKE A RUN
FOR WRN MN EARLY THIS EVENING BEFORE WE LOSE DAYTIME HEATING. AS A
RESULT...REMOVED POPS AFTER 3Z. THALER QG DIAGNOSTICS SHOWS
SUBSIDENCE DOMINATING MN/WI TONIGHT AND WITH THE LOSS OF DIURNAL
HEATING...ALL CAMS SHOW ACTIVITY DISSIPATING. ALTHOUGH THE NAM/GFS
CONTINUE TO SHOW SOME LIGHT QPF ACROSS MN THROUGH THE
NIGHT...DECIDED TO SIDE MORE TOWARD THE FORCING THAN MODEL GENERATED
QPF IN GOING WITH THE DRY FORECAST AFTER 3Z.
FOR HIGHS TODAY...DO EXPECT A DESCENT AMOUNT OF SUNSHINE FOR THE
LATE MORNING THROUGH MUCH OF THE AFTERNOON...WITH H85 TEMPS EXPECTED
TO BE A COUPLE OF DEGREES ON EITHER SIDE OF 16C. BUFKIT SOUNDINGS
SHOW US MIXING UP TO ABOUT 825 AND MIXING THOSE TEMPERATURES DOWN TO
THE SFC ON THE NAM SPIT BACK OUT HIGHS IN THE MID/UPPER 70S...SO DID
NUDGE HIGHS UP A FEW DEGREES...WHICH SIMPLY PUT US TOWARD THE HIGHER
END OF THE GUIDANCE ENVELOP.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 340 AM CDT MON SEP 1 2014
SIGNS OF EARLY FALL ARE IN THE AIR WITH A PERSISTENT WEST COAST
TROUGH AND WESTERLY FLOW ACROSS THE UPPER MISSISSIPPI THROUGH THE
EXTENDED. THERE ARE ALSO A STRONG COLD FRONTS EXPECTED OVER THE NEXT
7-10 DAYS PRECEDED BY BRIEF BOUTS OF WARMTH AND INCREASED
HUMIDITY.
TUESDAY SHOULD FEATURE QUIET AND PLEASANT WEATHER WITH MID-LEVEL
HEIGHT RISES...AND SURFACE RIDGING JUST SOUTH OF THE FORECAST AREA.
WARM AIR ADVECTION SHOULD BEGIN IN EARNEST BY TUESDAY AFTERNOON AS
WARMER AIR FROM THE PLAINS REPLACES THE COOLER AIR MASS TIED TO
MONDAY`S TROUGH. WEDNESDAY LOOKS LIKE THE MOST INTERESTING DAY OF
THE UPCOMING WEEK IN TERMS OF THUNDER POTENTIAL AND EVEN SMALL
PROBABILITIES FOR SEVERE WEATHER IN MN. A FAST MOVING UPPER WAVE
WILL MOVE FROM THE PACIFIC NORTHWEST TO NEARLY HUDSON BAY IN
APPROXIMATELY 48 HOURS. A SURFACE LOW IS EXPECTED TO DEVELOP IN THE
DAKOTAS AND MOVE INTO NW MN BY 12Z THURSDAY. THE LOCATION OF THE
ASSOCIATED WARM FRONT SHOULD FOCUS A MAJORITY OF THE CONVECTION
ACROSS THE NORTHERN HALF OF MN...WITH THE 01.00Z GFS/NAM/ECMWF
KEEPING QPF BULLS EYE NORTH OF I-94. THERE IS THE POTENTIAL FOR
STRONG TO SEVERE STORMS NEAR THE WARM FRONT. BOTH THE GFS/NAM
GENERATE 2000-2500J/KG OF MUCAPE BY 21-00Z WEDNESDAY. THERE IS ALSO
DECENT FLOW ALOFT WITH 30-40KTS OF DEEP LAYER SHEER AND A VEERING
HODOGRAPH. SOUTH OF THE MOST ROBUST CONVECTION...IT SHOULD BE WARM
AND STEAMY. WARMEST PLUME OF 850MB ARRIVES THURSDAY
MORNING...SETTING UP ANOTHER POTENTIALLY WARM AND HUMID DAY IN THE
EASTERN FORECAST AREA ON THURSDAY. BOTH WEDNESDAY AND THURSDAY COULD
FEATURE A LOT OF HEAT INDICES IN THE UPPER 80S AND LOWER 90S. A
STRONG COLD FRONT PASSES THROUGH BY FRIDAY AND WILL RESULT IN A DRY
AND COOLER WEEKEND UNDER HIGH PRESSURE. SO IT LOOKS A FAIRLY QUIET
EXTENDED UNTIL PERHAPS THE MIDDLE OF NEXT WEEK WHEN ANOTHER BRIEF
WARM-UP AND SHARP COLD FRONT ARE SHOWING UP OFF THE GFS AND ECMWF.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1219 AM CDT MON SEP 1 2014
THUNDER THREAT LARGELY DONE ACROSS THE MPX AIRSPACE...BUT STRONG
UPPER WAVE BACK BY SIOUX FALLS STILL HAS TO WORK ACROSS SRN MN/WRN
WI TONIGHT...WHICH WILL KEEP SCT SHOWERS GOING THROUGH MUCH OF THE
NIGHT...AS WE ARE SEEING WITH THE HRRR. BIGGER QUESTION MARK
REVOLVES AROUND STRATUS/FOG POTENTIAL TONIGHT. CERTAINLY THIS
STRATIFORM RAIN WE ARE SEE OUT THERE NOW WILL HELP MOISTEN THE
ATMO AND INCREASE THE THREAT FOR STRATUS...BUT CIGS AT THE START
ARE LARGELY UP AROUND 10K FT...SO WE HAVE A WAYS TO GO. FOLLOWED
THE IDEA OF THE RAP THOUGH WITH STATUS EVENTUALLY FILLING IN
WITHIN AND EAST OF THE WEAKENING SFC TROUGH...WHICH AT 6Z
STRETCHED FROM ABOUT NEW ULM TO MILLE LACS LAKE. THIS MOISTURE
LOOKS TO GET SCOURED OUT PRETTY QUICK BY WNW WINDS IN THE
MORNING...WITH MOST OF LABOR DAY GOING BY WITH VFR CONDS. DURING
THE LATE AFTERNOON...ANOTHER UPPER WAVE WILL BE COMING OUT OF THE
DAKOTAS...BUT IT LOOKS TO DO NOTHING MORE THAN PROVIDE US WITH AN
INCREASE IN MID CLOUDS AND PERHAPS A FEW SPRINKLES AS WE HEAD INTO
MONDAY NIGHT.
KMSP...STRATIFORM RAIN WE ARE SEEING NOW FAVORED ME TOWARD KEEPING
THE DEVELOPMENT OF SUB 018 CIGS WE HAD IN THE TAF...BUT WITH CIGS
STILL ABOVE 5K FT...NOT COMPLETELY SOLD ON THOSE RESTRICTIONS
HAPPENING. OTHER THAN THAT...NO OTHER CONCERNS ARE EXPECTED THIS
PERIOD.
/OUTLOOK FOR KMSP/
TUE...VFR. WINDS WSW 5-10 KTS.
WED...VFR. CHC MVFR/TSRA LATE. WINDS S 5-10 KTS.
THU...VFR. CHC MVFR/TSRA. WINDS S BCMG W 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...CLF
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1233 AM CDT MON SEP 1 2014
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 252 PM CDT SUN AUG 31 2014
SVR WX PARAMETERS REMAIN FAVORABLE FOR LARGE HAIL/DAMAGING WINDS
THIS AFTN/EARLY EVENING. THE MAIN PROBLEM IS AFTN CAP /BASED ON
18Z KMPX SOUNDING/ WHICH HAS SUPPRESSED MOST OF THE CONVECTION
ACROSS SOUTHERN MN EARLY THIS AFTN. IN ADDITION...THE MAIN SHRTWV
AND UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE JET CORE MOVING
ACROSS COLORADO...IS NOT EXPECTED TO MOVE ACROSS NE/IA/MN UNTIL
LATER THIS EVENING. A STRONGER STORM NORTH OF KOMA AS OF 19Z IS A
REFLECTION OF A STRENGTHENING LLJ AHEAD OF THIS JET ENERGY MOVING
OUT OF COLORADO.
SHORT TERM MESOSCALE CONVECTIVE PARAMETERS /HRRR/RUC/ HAVE
DEPICTED THAT THE SHRA/TSRA ACROSS SOUTHERN MN SHOULD BE MOVING
ACROSS EASTERN MN/WESTERN WI BY 00Z...WITH MOST OF THE
STRONGER/SVR ACTIVITY FORMING SOUTH ACROSS IOWA. IN
ADDITION...THESE SAME MESOSCALE CONVECTIVE PARAMETERS HAVE ANOTHER
LINE OF SHRA/TSRA FORMING WEST OF THE TWIN CITIES ARND 2-4Z ALONG
AND AHEAD OF THE APPROACHING SFC FRONT. THIS MAY BE THE MAIN
PLAYER TONIGHT...AS SAID BEFORE...THE AFTN CAP WILL LIKELY HOLD
FOR A FEW MORE HRS...SETTING THE STAGE FOR AN EVENING EVENT.
OTHERWISE...SHRA/TSRA SHOULD CONTINUE TO FORM ALONG AND AHEAD OF
THIS SFC FRONT LATER THIS EVENING AND MOVE EASTWARD DURING THE
OVERNIGHT HRS. BY MORNING...MOST OF THE ACTIVITY SHOULD BE EAST OF
MPX FA...WITH ONLY RESIDUAL SHRA IN WC WI.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 252 PM CDT SUN AUG 31 2014
TUESDAY-WEDNESDAY...THE FIRST COUPLE DAYS OF THE EXTENDED PORTION
WILL BE DOMINATED BY GENERALLY ZONAL FLOW ALOFT WHILE SFC HIGH
PRES OVER THE CENTRAL PLAINS SHIFTS E INTO THE OHIO VALLEY. THIS
WILL SPELL A WEAK PRES PATTERN OVER THE UPR MISS RIVER VALLEY
REGION WITH WEAK SUPPORT ALOFT. HOWEVER...THE RELATIVELY WEAK
INFLUENCE OF HIGH PRESSURE AS IT STAYS S OF THE REGION MEANS THAT
THERE WILL BE FAIRLY INEFFECTIVE CAPPING WITHIN A CONTINUED DEEPLY
MOIST ENVIRONMENT. WEAK BUCKLES IN THE ZONAL FLOW CAN EASILY SPARK
ISOLD SHOWERS AND POSSIBLY EVEN A HANDFUL OF TSTMS ACRS THE REGION
DURING THIS PERIOD SO SPOTTY SLGT CHC POPS ARE MAINTAINED IN THE
FCST. MUCH OF THE FCST AREA WILL REMAIN DRY...BUT ANY LOCATIONS
THAT DO SEE SOME PRECIP WILL NOT RECEIVE MUCH IN THE WAY OF QPF.
OTHERWISE...TEMPS AND DEWPOINTS WILL GO ON A SLIGHT INCREASING
TREND AS WINDS SHIFT FROM WLY TO SLY ON THE BACKSIDE OF THE
DEPARTING HIGH PRES AREA.
WEDNESDAY NIGHT-THURSDAY NIGHT...A LARGE LONGWAVE TROUGH DROPPING
OUT OF THE GULF OF ALASKA MON WILL MOVE ONSHORE THE PAC NW
REGION TUE EVE AND SLOWLY MAKE ITS WAY INTO THE CENTRAL CONUS
DURING THE MIDDLE PORTION OF THE WEEK. THIS TROUGH WILL PICK UP A
DEVELOPING LOW PRES CENTER OVER MT...SHIFTING IT INTO THE DAKOTAS
AND EVENTUALLY NRN MN BY MIDDAY THU. THE COMBINATION OF THE
DIGGING TROUGH AND THIS LOW PRES CENTER DEEPENING OVER THE ERN
DAKOTAS AND MN WILL CREATE ADDITIONAL POTENTIAL FOR SCATTERED
SHOWERS AND THUNDERSTORMS FOR MUCH OF THE AREA LATE WED THRU THU
NIGHT. THE FRONT LOOKS TO STALL OUT OVER CENTRAL MN THU...SO THIS
MAY ALTER THE DURATION OF HAVING POPS IN THE FCST OVER THE NEXT
FEW DAYS WORTH OF MODEL RUNS.
FRIDAY-SUNDAY...THOUGH THE SFC REFLECTION OF THE LOW PRES SYSTEM
LOOKS TO BE E OF THE WFO MPX CWFA BY DAYBREAK FRI MRNG...THE
ASSOCIATED TROUGH AXIS ALOFT WILL BE DRAGGING ITS WAY THROUGH THE
REGION DURG THE DAY ON FRI. THIS MAY LEAD TO SOME SHOWERS WITH THE
RELATIVE CORE OF THE SYSTEM STILL PASSING THRU. BEHIND THESE
DISTURBANCES AT THE SFC AND ALOFT...MORE PRONOUNCED NW FLOW ALOFT
WILL DOMINATE THRU THE WEEKEND WHILE HIGH PRES SLOWLY SHIFTS SE.
THIS COMBINATION WILL ALLOW FOR A DRYING OUT PERIOD FOR NEXT
WEEKEND ALONG WITH COOLER AND LESS HUMID CONDITIONS. HIGHS WILL
DROP BACK TO THE UPR 60S AND LWR 70S BY NEXT WEEKEND WITH LOWS
FALLING INTO THE UPR 40S AND LWR 50S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1219 AM CDT MON SEP 1 2014
THUNDER THREAT LARGELY DONE ACROSS THE MPX AIRSPACE...BUT STRONG
UPPER WAVE BACK BY SIOUX FALLS STILL HAS TO WORK ACROSS SRN MN/WRN
WI TONIGHT...WHICH WILL KEEP SCT SHOWERS GOING THROUGH MUCH OF THE
NIGHT...AS WE ARE SEEING WITH THE HRRR. BIGGER QUESTION MARK
REVOLVES AROUND STRATUS/FOG POTENTIAL TONIGHT. CERTAINLY THIS
STRATIFORM RAIN WE ARE SEE OUT THERE NOW WILL HELP MOISTEN THE
ATMO AND INCREASE THE THREAT FOR STRATUS...BUT CIGS AT THE START
ARE LARGELY UP AROUND 10K FT...SO WE HAVE A WAYS TO GO. FOLLOWED
THE IDEA OF THE RAP THOUGH WITH STATUS EVENTUALLY FILLING IN
WITHIN AND EAST OF THE WEAKENING SFC TROUGH...WHICH AT 6Z
STRETCHED FROM ABOUT NEW ULM TO MILLE LACS LAKE. THIS MOISTURE
LOOKS TO GET SCOURED OUT PRETTY QUICK BY WNW WINDS IN THE
MORNING...WITH MOST OF LABOR DAY GOING BY WITH VFR CONDS. DURING
THE LATE AFTERNOON...ANOTHER UPPER WAVE WILL BE COMING OUT OF THE
DAKOTAS...BUT IT LOOKS TO DO NOTHING MORE THAN PROVIDE US WITH AN
INCREASE IN MID CLOUDS AND PERHAPS A FEW SPRINKLES AS WE HEAD INTO
MONDAY NIGHT.
KMSP...STRATIFORM RAIN WE ARE SEEING NOW FAVORED ME TOWARD KEEPING
THE DEVELOPMENT OF SUB 018 CIGS WE HAD IN THE TAF...BUT WITH CIGS
STILL ABOVE 5K FT...NOT COMPLETELY SOLD ON THOSE RESTRICTIONS
HAPPENING. OTHER THAN THAT...NO OTHER CONCERNS ARE EXPECTED THIS
PERIOD.
/OUTLOOK FOR KMSP/
TUE...VFR. WINDS WSW 5-10 KTS.
WED...VFR. CHC MVFR/TSRA LATE. WINDS S 5-10 KTS.
THU...VFR. CHC MVFR/TSRA. WINDS S BCMG W 10-15 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...JLT
LONG TERM...JPC
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1151 PM CDT Sun Aug 31 2014
.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 357 PM CDT SUN AUG 31 2014
Afternoon water vapor imagery showing long advertised Pacific trough
digging into the central Plains this afternoon...with strong
shortwave energy now seen entering western Nebraska. Strengthening
wind fields along the southern edge of this feature have advected
Mexican Plateau air /i.e. elevated mixed layer/ east across the
central/southern Plains as seen on the latest 7.4 micron water vapor
GOES sounder channel. Latest RUC analysis shows 7-500 mb lapse rates
approaching 9C/km across western Kansas and Nebraska...and fcst
models suggest this mid-level airmass will continue tracking east
into our region overnight. Along the surface...latest analysis shows
a developing leeside low across southeastern Colorado...with a
northward extending frontal boundary draped across the Plains which
then joins the main area of low pressure now found along the
Minnesota/Manitoba border. With time this evening...aforementioned
boundary will progress eastward as upstream troughing continues to
settle into the central and southern Plains. Airmass ahead of both
the cold front and upper wave continues to destabilize with latest
SPC meso graphics yielding as much as 3500 joules of MLCAPE between
KC and Topeka. Most importantly however...deep layered shear will
continue increasing as well as mid- level wind max moves into the
area overnight. All said...ingredients appear to be coming together
for a fairly active evening and overnight period.
Latest radar trends now showing developing cells across north-central
Kansas along the previously mentioned frontal boundary. Storms
should continue to fire this afternoon before gradually spreading east
through the early evening and overnight. As has been advertised in
recent days quite well by numerical models...isolated convection to
our west and north will likely congeal into a forward propagating MCS
this evening just before it enters northwestern Missouri. As this
occurs...deep layered shear will continue to strengthen as a low-
level jet increases to nearly 50 kts directly overhead. This poses
two potential issues for our region:
1) Maintenance of ongoing severe weather as cold pool continues to
track southeast with time into northwest Missouri/northeast Kansas
2) Increasing likelihood for developing heavy rain/possible flooding as
low-level jet ascends any convectively generated cold pools
The above said...main concerns severe-wise for our area will remain
strong damaging winds as cold pool for developing MCS tracks south
and east with time. Current thinking is damaging wind potential will
gradually decrease as storms approach the greater KC area...however
cannot rule out strong gusts in and around the metro during the late
evening hrs. Additionally...a low-end tornado threat does exist across
far northwest Missouri as strong updrafts continue to tilt horizontal
vorticity into the vertical along the leading edge of the cold pool
as it tracks south and east with time. For now...agree completely with
where SPC has the highest tornado threat /NW MO/ as further progress
to the south and east will likely result in a less favorable
environment due to nocturnal cooling/low-level stabilization effects.
In terms of hydro concerns...have elected to go with a flash flood
watch for much of northwest MO/northeast Kansas as potential exists
for training convection if an outflow boundary lays out across
central Missouri. As alluded to above...strength of developing low-
level jet is a little concerning especially when PWAT values are
expected to increase to anywhere between 2-3 standard deviations
above normal as main front approaches. HPC QPF shows a 2+ inch
bullseye directly west of KC which appears to be in favor of
developing training after midnight. Would rather play it safe hence
the current flash flood watch which runs from 2z this evening through
15z Monday morning.
Front to slowly settle south of the region during the early morning
hrs. Another round of strong to severe storms is possible on
Monday...primarly south of the the greater KC area as daytime
heating combines with still impressive wind fields aloft. For
tomorrow...more optimal timing may support isolated supercell
structures as opposed to tonight/s linear activity. Regardless...have
maintained likely pops for most areas south of I-70 during the
afternoon hrs.
Front to clear the area tomorrow night which should support a mostly
dry Tuesday. Front slowly expected to lift north as a warm front
through the day on Wednesday but minimal impacts expected as no
significant features are at play to enhance upward vertical motion.
Temps by then should begin to rise with low to mid 90s possible
Wednesday afternoon as southerly flow reinvades the area.
.LONG TERM...(Wednesday Evening through Sunday)
Issued at 357 PM CDT SUN AUG 31 2014
A little bit of everything during the extended portion of the
forecast. Storms early Wednesday, followed by a return of hot and
humid air until a cold front and more storms on Friday, then finally
some fall-like weather over the weekend.
Medium range models all on the same page with the overall pattern.
Mid-week zonal flow backs to the southwest in response to an upper
trough tracking east from the Northern Rockies through the Upper MS
Valley by Friday.
Elevated convection associated with a northward returning warm front
will affect the CWA early Wednesday followed by hot and humid air
spreading back into the region. This will likely last into Friday
when the southern extension of the Northern Plains upper trough
forces a cold front south and through the Mid MO River Valley by
Saturday morning. Moderately strong and broad area of high pressure
expanding southward will bring some much needed relief from the high
humidities.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1151 PM CDT SUN AUG 31 2014
Line of storms that affected the terminals tonight has moved through as
of this time, leaving strati-form rain and VCTS as the primary weather
at our sites currently. This activity could last through 11Z at the
Kansas City terminals, but should end sooner at KSTJ --09Z--.
Otherwise, expect southerly winds to prevail for much of the day
behind the exiting rain. There will be a returning threat for
thunderstorms generally near and south of Kansas City again Monday
afternoon, so have inserted VCTS in after 21Z.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...FLASH FLOOD WATCH until 10 AM CDT Monday FOR KSZ025-102>105.
MO...FLASH FLOOD WATCH until 10 AM CDT Monday FOR MOZ001>005-011>014-
020>022-028>030-037.
&&
$$
SHORT TERM...32
LONG TERM...MJ
AVIATION...Cutter
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1123 PM CDT Sun Aug 31 2014
.UPDATE:
Issued at 905 PM CDT Sun Aug 31 2014
Progressive UA trof and associated cold front, as well as outflow
boundaries produced by intense convection so far this evening,
should cause convection stretching from western Iowa to central KS to
push across the NW half of our FA overnight. Rough timing based
on extrapolation of upstream radar data suggests leading edge of
precip moving into the Edina area by 05z/midnight. While we are
missing much of today`s explicit guidance, from the data that is
available believe that the latest HRRR output has a best handle on
overnight trends in two aspects...being faster with the eastward
progression and suggesting that some precip may be knocking on the
western door of the STL metro by daybreak, and secondly more of a
focus on late night/predawn convection over eastern KS/W MO where
there should be good cold pool/low level jet interaction which
should focus the most robust convection in this area.
Forecast inherited from dayshift already trended specifics towards
the trends mentioned above, so going forecast looks quite good and
only minor adjustments needed to speed up onset of higher PoPs by
1-2 hours. If HRRR scenario does pan out I`m not too certain
about how much of a severe weather threat will reach our area, but
as mentioned by day shift there will likely be at least some
impact from upstream outflows that propagate east and produce
gusty winds.
Specific trends for Labor Day and Monday night...including the
potential for severe weather and heavy rain...will largely hinge on
how convection evolves across the region during the predawn hours
and into Monday morning; specifically how long the early morning
convection lingers and where the associated outflow boundary will be
located during the afternoon. While there is still quite a bit of
uncertainty on how the convection will evolve, it certainly appears
that outdoor plans may be altered in many areas due to the
weather.
Update will be issued as soon as 02x surface data can be ingested
and assimilated into database.
Truett
&&
.SHORT TERM: (Through Late Tonight)
Issued at 350 PM CDT Sun Aug 31 2014
Isolated to widely scattered thunderstorms over southeast portions
of the CWFA should dissipate fairly quickly this evening. Until
then, locally heavy downpours will continue over parts of the
eastern Ozarks. Attention turns to tonight as a strong shortwave
will move from eastern Wyoming into the eastern Nebraska/northwest
Missouri. An MCS is expected to develop ahead of it on the nose of
a 40kt low level jet over the eastern Plains. The model consensus
keeps the vast majority of the precipitation over western/north
central Missouri tonight. However, it does look like the leading
edge will nose into central and northeast Missouri between 08Z and
12Z. Not sure how much of the strength of the storms by that
point. Current thinking is that the cold pool may outrun the best
forcing causing the MCS to weaken as it moves east. This scenario
would have the rain moving into western portions of the CWFA between
08Z and 10Z. There may be some gusty winds as the outflow moves
through, but the most significant impact would likely be locally
heavy rain; and that looks more likely over western Missouri than in
central Missouri.
Carney
.LONG TERM: (Monday through Next Sunday)
Issued at 350 PM CDT Sun Aug 31 2014
We will see a break in what has been a hot pattern for us this past
week, as the upper level ridge breaks down, thanks to a pair of
decently strong shortwave TROFs. Much of the energy from these
shortwaves will pass us to the north, but nevertheless, we are
expecting high probabilities of rain from both of these systems
because of either a favorable position of the low level jet or
synoptic front and a very moist, deep warm-cloud atmosphere.
The first system is expected to be ongoing early Monday morning for
areas north and west of STL metro while in a slowly weakening
state. This rain is expected to reach the STL metro area before
dissipating or scattering out, with an anticipated boundary setup
near or just south of the I-70 corridor for new development in the
afternoon. There is also some potential for scattered development
Monday afternoon further north and west near the synoptic front in
northern MO and central IL.
The second system on Monday night should make more of a pass to the
south and interact with the synoptic front now deeper into our
region and favorable axis of the low level jet. In addition, there
is potential for localized heavy rainfall with PWs of around 2
inches and warm-cloud depths in excess of 4km and training storms.
The front is then expected to stall over southern MO Tuesday before
pushing north as a warm front on Wednesday with persistent, but
lesser, chances for storms.
While the humidity air never really goes away thru late week, it
should be just cool enough to prevent any dangerous heat and
humidity conditions until perhaps when the warm front pushes thru
Wednesday and into Friday.
A period of dry weather is anticipated Thursday through early Friday
with a warm-sector setup, with the next, and what looks to be much
stronger, cold front pushing thru late Friday thru early Saturday.
Increased chances for rain will return with the front with all early
indications showing a cool and dry period next weekend for most
areas.
TES
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1103 PM CDT Sun Aug 31 2014
Convection extending from IA southwest through northwestern MO and
KS just ahead of a cold front will drop southeastward into the
UIN and COU areas late tonight, and then eventually into the St
Louis metro area towards morning as it weakens. New convective
development is expected late Monday afternoon and early evening
mainly in COU and the St Louis metro area between the approaching
cold front and an outflow boundary left from the late
night/morning storm complex. S-sely surface winds late tonight
will gradually veer around to a swly direction Monday morning.
Specifics for KSTL: Weakening showers and storms are expected to
drop southeastward into STL area by early Monday morning. There
will be a break in the convection with redevelopment of storms
expected late Monday afternoon and evening. S-sely surface winds
late tonight wlll increase to around 14 kts by late Monday
morning from a swly direction.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1129 PM CDT SUN AUG 31 2014
.UPDATE...
ISSUED AT 1115 PM CDT SUN AUG 31 2014
NO MAJOR CHANGES PLANNED...SHOULD BE A DRY NIGHT. THERE COULD BE
SOME PATCHY FOG WHERE SKIES CLEAR...BUT FOR NOW FEEL ITS NOT WORTH
A MENTION WITH THE HRRR NOT INDICATING ANY LOW VSBYS...BUT
SOMETHING FOR THE MID SHIFT TO WATCH.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 305 PM CDT SUN AUG 31 2014
AS OF 20Z...THE REGION IS IN A RELATIVELY QUIET PERIOD BETWEEN
UPPER WAVES (ALTHOUGH AREAS OF DRIZZLE/LIGHT RAIN MAY BE
PERSISTING). THE NEXT WAVE WILL PROPAGATE INTO THE REGION FROM THE
SOUTHWEST...AND SPREAD SHOWERS INTO PORTIONS OF THE SOUTHERN FA.
MOST GUIDANCE SUGGESTS COVERAGE WILL DISSIPATE AS THE STRONGER
ACTIVITY INITIATES ACROSS NEBRASKA/IOWA. LATEST MESOSCALE ANALYSIS
INDICATES MLCAPE AOA 1000 J/KG ALONG AND EAST OF A LINE FROM KBJI
TO KBWP. HOWEVER...MLCIN IS STILL 60-80 J/KG...AND ANTICIPATE THIS
AIRMASS TO BE EAST OF THE FA (AS MORE STABLE/DRIER AIR ADVECTS IN
FROM THE WEST) BY THE TIME MLCIN IS WEAK ENOUGH FOR THUNDER
INITIATION. STILL CANNOT RULE OUT AN ISOLD SHOWER/STORM THIS
EVENING...BUT CHANCES APPEAR VERY LOW (AND HIGH RES MODELS AGREE).
MUCH OF TONIGHT INTO MONDAY WILL BE DRY. HOWEVER...THE REGION DOES
REMAIN IN GENERAL CYCLONIC FLOW ALOFT...AND THERE SHOULD BE WEAK
UPPER WAVES ROTATING THROUGH THE REGION. DID INTRODUCE SLIGHT
THUNDER CHANCES FOR MONDAY AFTERNOON/EVENING WHEN MODELS AGREE ON
A STRONGER UPPER WAVE THAT WOULD INTERACT WITH WEAK INSTABILITY
FROM DAYTIME HEATING.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 305 PM CDT SUN AUG 31 2014
TUESDAY-WEDNESDAY...MUCH LIKE THE SHORT TERM PERIOD...WEAK UPPER
WAVES IN THE UPPER FLOW PATTERN COULD LEAD TO PRECIP...BUT MOST
AREAS SHOULD BE DRY A MAJORITY OF THE PERIOD. THE MAIN CONCERN
WILL BE WEDNESDAY AFTERNOON AS MODELS INDICATE A WARM FRONTAL TYPE
BOUNDARY LIFTING INTO WEST CENTRAL MINNESOTA...WHICH MAY LEAD TO
STRONGER THUNDERSTORM POTENTIAL.
WEDNESDAY NIGHT-SUNDAY...LONG TERM MODELS ARE IN GOOD AGREEMENT
WITH OVERALL UPPER AIR PATTERN AND PLACEMENT OF PRECIP FOR MID
WEEK CHANCES OF CONVECTION. BOTH MODELS SHOWING AN UPPER
LOW/TROUGH OVER SRN SASK AROUND 06Z THU MOVE INTO WRN ONTARIO BY
00Z FRI. SW FLOW OVER THE DAKOTAS WILL BRING A CHANCE OF
CONVECTION TO NORTHERN AND NORTHEASTERN ZONES WED NIGHT THROUGH
THU NIGHT. NW FLOW THEN RETURNS WITH A COOL AND DRY AIRMASS IN
PLACE...BRINGING COOLER THAN NORMAL TEMPS TO THE REGION. THIS DRY
PERIOD SHOULD BE IN PLACE BY FRI AND CONTINUE THROUGH NEXT WKND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1115 PM CDT SUN AUG 31 2014
EXPECT VFR CONDITIONS WITH THE CHANCE OF SOME PATCHY FOG LATER
TONIGHT WHERE IT CLEAR. FOR NOW WILL NOT MENTION ANY FOG...BUT
SOMETHING TO KEEP IN MIND. THERE WILL BE A FEW SHOWERS AND STORMS
MONDAY AFTERNOON MOVING FROM WEST TO EAST. WILL MENTION SOME VCSH
IN THE 19-3Z TIMEFRAME...BUT HOLD OF ON THUNDER MENTION WITH
FAIRLY ISOLATED COVERAGE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...DK
SHORT TERM...TG
LONG TERM...TG/SPEICHER
AVIATION...DK
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
108 AM CDT MON SEP 1 2014
.UPDATE...
06Z AVIATION DISCUSSION UPDATED BELOW.
&&
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
POTENT SHORTWAVE EVIDENT ON WATER VAPOR OVER WYOMING. AHEAD OF
THIS WAVE...OMEGA AND UPPER JET MAX HELPING TO MAINTAIN BAND OF
RAINFALL THAT HAS TREKKED FROM SOUTH CENTRAL SD TO NORTHEAST SD
OVER THE PAST SEVERAL HOURS. HAVE BEEN ADJUSTING POPS FOR THIS
BAND OF RAIN AS IT APPEARS IT WILL SURVIVE MOST IF NOT ALL THE WAY
ACROSS THE CWA. HRRR PICKING UP ON THIS QUITE NICELY.
OVERNIGHT...EXPECTING SCATTERED SHOWERS AND STORMS TO MOVE EAST
ACROSS THE STATE BUT WITH MINIMAL SEVERE THREAT DUE TO LACK OF
INSTABILITY. ONLY QUESTION IS THE DEGREE OF AREAL COVERAGE OF
PRECIP. SOME MODELS GREATER THAN OTHERS...WITH THE HRRR
PARTICULARLY DRY AND SORT OF THE OUTLIER. MOST OTHER MODELS HAVE
ACTIVITY MOVING ACROSS AT LEAST THE SOUTHERN HALF OF SD TONIGHT.
HAVE ADJUSTED POPS ACCORDINGLY AND LINGERED THEM A BIT LONGER
THROUGH THE NIGHT AS NSSL WRF STILL SHOWS CONVECTIVE CLUSTERS OVER
SOUTHEAST SD AT 09Z TONIGHT.
A WEAKER WAVE MOVES ACROSS THE AREA MONDAY...BUT SHOULD STILL
PROVIDE FOR A FEW SCATTERED SHOWERS OR STORMS. AREAL COVERAGE DOES
NOT APPEAR IT WILL QUITE MATCH UP TO WHATS MOVING INTO WESTERN SD
RIGHT NOW...BUT WORTHY OF 20/30 POPS NONETHELESS. AGAIN A LACK OF
INSTABILITY TOMORROW SO SEVERE THREAT IS VERY LOW.
TUESDAY STILL LOOKS DRY WITH NO NOTABLE SYSTEMS IN THE AREA. 500
MB HEIGHTS RISE SLOWLY THROUGH THE DAY WITH WARM AIR ADVECTION
DEVELOPING. HIGHS WILL BUMP UP INTO THE UPPER 70S TO LOW 80S FOR
MOST AREAS.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
THE EARLY PART OF THE PERIOD STARTS OFF SOMEWHAT ACTIVE AS FAIRLY
STRONG SYSTEM MOVES ACROSS THE NORTHERN PLAINS. LATEST MODELS ARE
IN FAIR AGREEMENT ON AVAILABLE MOISTURE/INSTABILITY BUT DO SUGGEST
CAPPING MIGHT FORCE MOST ACTIVITY TO REMAIN NORTH OF THE CWA
WEDNESDAY NIGHT INTO THURSDAY AS COLD FRONT MOVES EAST. THUS POPS
NO HIGHER THAN CHC NEEDED AT THIS POINT. BEHIND THE FRONT IT LOOKS
FAIRLY DRY FROM THURSDAY THROUGH SUNDAY AS HIGH PRESSURE PROVES
DOMINANT. TEMPERATURES WILL START OFF ABOVE NORMAL AT THE
BEGINNING OF THE PERIOD THEN TREND TOWARD NORMAL OR EVEN BELOW BY
THE END OF THE WEEK.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A SHORT WAVE TROUGH MOVING EAST OF THE REGION TONIGHT WILL TAKE
THE VFR MID LEVEL CLOUDS AND SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITH IT. THESE MAY AFFECT ABR AND ATY.
OTHERWISE...ANOTHER SHORT WAVE TROUGH WILL DROP INTO THE REGION
FROM THE NORTHWEST LATE THIS MORNING THROUGH THIS EVENING. WITH
STEEP LAPSE RATES...SOME INSTABILITY AND MID LEVEL MOISTURE
...EXPECT MORE MID LEVEL CLOUDS ALONG WITH SCATTERED SHOWERS/STORMS
TO DEVELOP AGAIN. SOME OF THESE MAY AFFECT THE TERMINALS. INSERTED
SOME VICINITY SHOWERS IN AT ALL LOCATIONS. THESE WILL MOVE ON TO
THE EAST MONDAY EVENING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...MOHR
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1155 PM CDT SUN AUG 31 2014
.UPDATE...FOR 06Z AVIATION.
&&
.AVIATION...06Z TAF DISCUSSION.
SKIES HAVE BEEN CLEARING OVER THE MID-STATE FOR THE LAST COUPLE OF
HOURS. THERE IS STILL A POTENTIAL FOR AN IFR CLOUD DECK TO DEVELOP
OVER THE NEXT SEVERAL HOURS ACROSS SOUTHERN PORTIONS OF THE STATE
AND SLIP NORTHWARD OVER ALL 3 TERMINALS. WHILE THERE ARE NO
INDICATIONS OF THIS WANTING TO HAPPEN IN THE CURRENT SATELLITE
IMAGERY...SOME OF THE SHORT TERM-HI RES GUIDANCE IS SUGGESTING
THIS POSSIBILITY. EVEN IF THIS DOESN`T HAPPEN...WE MAY END UP WITH
IFR TO MVFR FOG BY SUNRISE. EITHER WAY...SOME FLIGHT CATEGORY
REDUCTION IS POSSIBLE OVERNIGHT.
SOUTHERLY WINDS WILL REMAIN LIGHT UNTIL LATE MORNING AND EARLY
AFTERNOON ON LABOR DAY WHEN SOUTHWESTERLY BREEZY CONDITIONS
DEVELOP. SOME GUSTS OF 16-20 KTS WILL BE POSSIBLE UNTIL 00Z
TUESDAY.
UNGER
&&
.PREV DISCUSSION... /ISSUED 842 PM CDT SUN AUG 31 2014/
UPDATE...
AT 830 PM...RADAR RETURNS WERE MOST DEFINITELY ON A DOWNWARD
TREND. SOME SLOW MOVING CELLS DROPPED HEALTHY AMOUNTS OF RAINFALL
OVER SE WILSON COUNTY ENOUGH TO WARRANT A FLOOD ADVISORY. DID
RECEIVE A CALL MENTIONING LOW LYING AREAS BECOMING INUNDATED IN
THAT AREA. HOWEVER...COVERAGE HAS DIMINISHED AND THE MID AND UPPER
LEVEL DYNAMICS HAVE MOVED OFF EAST OF THE PLATEAU. AS A
RESULT...LOWERED POP CHANCES ACROSS THE AREA UP UNTIL MIDNIGHT AND
REMOVED SLGT CHC POPS AFTER MIDNIGHT.
IR SATELLITE AND RUC FORECAST SOUNDINGS SHOW MID LEVEL DRYING OVER
THE REST OF THE EVENING AND OVERNIGHT...LIKELY RESULTING IN MOSTLY
CLEAR SKIES AT LEAST FOR A BIT BEFORE SOME BOUNDARY LAYER MOISTURE
ADVECTS NORTHWARD OUT OF NORTHERN ALABAMA DURING THE OVERNIGHT
PERIOD. SINCE SFC MOISTURE WILL STAY IN THE UPPER 60S AND LOW 70S
AND LOW LEVEL FLOW WILL STAY SOUTHWESTERLY...LEFT PATCHY FOG
MENTION IN THE GRIDS THROUGH THE FIRST PART OF THE MORNING. BUT
WITH DECENT WIND FIELDS IN THE BOUNDARY LAYER AND AT LEAST SOME
CLOUD COVER EXPECTED TOWARDS DAYBREAK...DID NOT SEE REASON TO
INCREASE THE FOG COVERAGE TO AREAS OR DENSE WORDING.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
141 AM EDT MON SEP 1 2014
.SYNOPSIS...
THE REGION WILL STAY BETWEEN A LARGE HIGH PRESSURE SYSTEM OVER
THE SOUTHEAST UNITED STATES AND A COMPLEX LOW PRESSURE SYSTEM
CROSSING THE GREAT LAKES. DISTURBANCES PASSING BETWEEN THESE TWO
FEATURES WILL COMBINE WITH HEAT AND HUMIDITY TO RESULT IN
PERIODIC CHANCES OF SHOWERS AND STORMS INTO EARLY WEEK. A COLD
FRONT FINALLY ARRIVES FROM THE NORTH WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 102 AM EDT MONDAY...
MADE SOME MINOR ADJUSTMENTS IN POPS AND TEMPERATURES FOR THIS
MORNING. SHAPED POPS THIS MORNING TOWARDS A BLEND OF RAP AND HRRR.
MORE CHANGES LATER THIS MORNING.
AS OF 920 PM EDT SUNDAY...
MAIN AXIS OF MOISTURE CONVERGENCE LIES FROM MD-CENTRAL WV. MAIN
UPPER IMPULSE THAT WAS OVER TN EARLIER HAS WEAKENED AS HAVE THE
SHOWERS UPSTREAM. OVERNIGHT NOT REALLY SEEING MUCH AS AIRMASS
STABILIZES. WILL KEEP THE HIGHER POPS OVER THE WV MTNS INTO FAR SW
VA...AS ANOTHER WEAK IMPULSE EDGES CLOSER TO THE MTNS BY DAWN.
OTHERWISE EXPECT MID DECK OF CLOUDS TO REMAIN IN THE WESTERN HALF
OF THE CWA WHILE THE EAST CLEARS SOME TOWARD MORNING. OVERALL FOG
THREAT IS PATCHY BUT COULD GET DENSE OUT EAST IF IT CLEARS OUT
ENOUGH. NO OTHER MAJOR CHANGES TO THE FORECAST THROUGH DAWN.
PREVIOUS VALID DISCUSSION...
SHORTWAVES WILL BE EXITING BY EARLY MONDAY LEAVING THE REGION IN DECENT
WEST/SW FLOW ALOFT BUT WITHOUT MUCH FORCING WELL IN ADVANCE OF THE NEXT
UPSTREAM 5H TROF/COLD FRONT TO THE NW. FORECAST SOUNDINGS SHOW QUITE A
DEEP WESTERLY FLOW WHICH RESULTS IN DRYING ALOFT/LOWERING PWATS ESPCLY
WEST MONDAY AFTERNOON AND A LEE TROUGH ACROSS THE PIEDMONT. MOST
GUIDANCE SOLUTIONS SHOW A LACK OF MUCH CONVECTION IN THIS REGIME WITH
ANY FOCUS PROVIDED BY OROGRAPHICS DUE TO WESTERLY CONVERGENCE AND
PERHAPS LATE DAY LOW LEVEL BACKING SE. THUS WILL LEAVE IN SOME LOW POPS
MAINLY WEST AS APPEARS A SUBTLE WAVE ALOFT COULD SNEAK THROUGH AROUND
THE TIME OF MAX HEATING. OTRW EXPECT WEAK LAPSES...LACK OF DEEP
INSTABILITY AND EASTERN DOWNSLOPE TO LIMIT OVERALL COVERAGE WITH MUCH
OF THE DAY LIKELY DRY AFTER EARLY MID DECK/FOG ERODE.
COULD BE ONE OF THE WARMEST DAYS SEEN IN A WHILE WITH 85H TEMPS PUSHING
+21C OVER DECENT DOWNSLOPE AND UNDER AMPLE AFTERNOON SUN. THIS WOULD
SUPPORT SOME MID 90S PIEDMONT...WITH UPPER 80S/LOW 90S BLUE RIDGE...
AND LOW/MID 80S WESTERN ELEVATIONS IF CAN GET A TEMP JUMP AFTER A WARM
START IN THE MORNING.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM EDT SUNDAY...
WITH WEAK HIGH PRESSURE BUILDING IN FROM THE SOUTH...EXPECT TO HEAD
INTO LATE MONDAY NIGHT WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. AS
SUCH...WOULD NOT BE SURPRISED TO SEE PATCHY FOG DEVELOP IN SOME OF
THE MOUNTAIN VALLEYS EARLY MORNING...WHICH WILL BURN OFF QUICKLY
SHORTLY AFTER 9 AM.
DURING TUESDAY AFTERNOON...SHOWER AND THUNDERSTORM ACTIVITY WILL
INCREASE AS AN UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT APPROACH
FROM THE WEST. ACTIVITY WILL START OFF ACROSS THE MOUNTAINS...SPOTTY
AT FIRST DUE TO THE WESTERLY DOWNSLOPE FLOW...AND THEN WILL SPREAD
EAST ACROSS THE PIEDMONT DURING THE EVENING AS THE UPPER LEVEL
ENERGY SHIFTS EAST. LIGHT WINDS AND WARM TEMPERATURES ALOFT WILL
LIMIT INSTABILITY...AND BELIEVE STRONG THUNDERSTORMS WILL BE
ISOLATED AND SHORT LIVED. SHOWER AND THUNDERSTORM ACTIVITY WILL THEN
DIMINISH THROUGH THE NIGHT WITH THE LOSS OF HEATING.
BY WEDNESDAY MORNING...WILL HAVE A WEAK BOUNDARY SITUATED ACROSS OUR
AREA...WHICH WILL EXHIBIT LITTLE MORE THAN A SHIFT IN WIND DIRECTION
FROM ONE SIDE TO THE OTHER AS THE TRULY COOLER AND DRIER AIR WILL
REMAIN WELL NORTH OF OUR AREA. REGARDLESS...THE LOW LEVEL
CONVERGENCE ALONG THE BOUNDARY WILL BE ENOUGH TO TRIGGER ANOTHER
ROUND OF SPOTTY SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND
EVENING. BETTER CHANCES FOR RAINFALL WILL BE FOUND SOUTH OF HIGHWAY
460.
TEMPERATURES HEADING INTO THE MIDDLE OF THE WEEK WILL BE WARMER THAN
NORMAL THANKS TO UPPER LEVEL RIDGING ACROSS THE SOUTHEAST STATES.
LOOK FOR HIGHS TO RANGE FROM THE LOW/MID 80S ACROSS THE MOUNTAINS...
TO THE LOW/MID 90S ACROSS THE SOUTHSIDE. OVERNIGHT LOWS WILL RANGE
FROM THE MID 60S WEST TO THE LOW 70S EAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 345 PM SUNDAY...
A WEAK BOUNDARY WILL REMAIN SITUATED ACROSS THE AREA ON
THURSDAY... PROVIDING THE LOW LEVEL FOCUS FOR SHOWERS AND
THUNDERSTORMS... MAINLY SOUTH OF HIGHWAY 460. ACTIVITY IS EXPECTED
TO REMAIN WIDELY SCATTERED DUE TO THE UPPER LEVEL RIDGE ACROSS THE
SOUTHEAST STATES BUILDING NORTH...HELPING TO LIMIT INSTABILITY.
HIGH PRESSURE WILL PASS ACROSS NEW ENGLAND...ALLOWING WINDS TO
SHIFT EASTERLY THROUGH THE DAY...AND THEN SOUTHEASTERLY DURING THE
EVENING.
AN APPROACHING UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT WILL
TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION ON
FRIDAY AND SATURDAY. THE COLD FRONT WILL MOVE ACROSS OUR AREA
SATURDAY NIGHT...USHERING IN COOLER AND DRIER CANADIAN HIGH
PRESSURE.
TROPICAL AIR WILL REMAIN ACROSS THE AREA THROUGH THE END OF THE
WEEK. AS SUCH...EXPECT WARM AND MUGGY CONDITIONS...WITH
TEMPERATURES HOLDING SLIGHTLY ABOVE NORMAL. COOLER TEMPERATURES
WILL ARRIVE WITH THE COLD FRONT AT THE END OF THE WEEK.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 127 AM EDT MONDAY...
A SHORTWAVE WILL LIFT NORTHEAST THIS MORNING ACROSS THE REGION.
A FEW SHOWERS WILL MOVE EAST ACROSS THE REGION THIS MORNING.
THE BEST CHANCE OF A SHOWER WILL OCCUR AT BLF AND LWB. IN THE
WAKE OF THE SHORTWAVE...THE OVERALL THREAT OF SHOWERS WILL FADE
WITH A SCT/BKN MID DECK LINGERING.
PATCHY FOG MAY DEVELOP THIS MORNING...BUT THE MID DECK SHOULD
LIMIT HOW FAR DOWN VSBYS DROP. WILL KEEP MOST TAF SITES NO WORSE
THAN MVFR THIS MORNING WITH LWB DROPPING OCCASIONALLY TO IFR
AFTER 10Z.
AHEAD OF THE UPSTREAM COLD FRONT...DEEP WESTERLY FLOW COMBINED
WITH LACK OF FOCUS AND DECENT MIXING SHOULD INHIBIT MUCH
CONVECTION TODAY ESPECIALLY IF EARLY MID DECK PERSISTS. THIS
SUPPORTS GOOD FLYING CONDITIONS FOR MUCH OF LABOR DAY AFTER EARLY
LOW CLOUDS/FOG FADE WITH ONLY ISOLATED CONVECTION LIKELY.
MEDIUM CONFIDENCE ON CEILINGS...VISIBILITIES AND WINDS DURING THE
TAF PERIOD.
EXTENDED DISCUSSION...
UPPER TROUGH AND ITS ASSOCIATED COLD FRONT WILL APPROACH FROM THE
NORTHWEST TUESDAY WITH SIMILAR ISOLATED SHOWERS/STORMS EXPECTED
DURING THE DAY AHEAD OF THE BOUNDARY. FRONT SETTLES CLOSER TUESDAY
NIGHT INTO WEDNESDAY...WHEN BETTER COVERAGE OF SHRA/TSRA IS
EXPECTED...AND THEN ACROSS THE SOUTH THURSDAY WHERE THE BOUNDARY
STALLS. HOWEVER LOW CONFIDENCE ON THE TIMING AND SOUTHWARD
POSITION OF THE BOUNDARY AT THIS POINT. THUS APPEARS MAINLY VFR
ON TUESDAY...WITH PERIODS OF MVFR WEDNESDAY-THURSDAY IN MORE
ORGANIZED MAINLY AFTERNOON/EVENING CONVECTION...AND MVFR/IFR UNDER
EARLY MORNING FOG IN THE VALLEYS AND WHERE EARLIER HEAVY RAIN
OCCURRED. FRONT WASHES OUT TO THE SOUTH OF THE AREA FRIDAY WITH
MORE DIURNAL NATURE SHOWERS AND STORMS...OTRW VFR.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/JH
NEAR TERM...JH/KK/WP
SHORT TERM...NF
LONG TERM...NF
AVIATION...JH/KK/WP
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
102 AM EDT MON SEP 1 2014
.SYNOPSIS...
THE REGION WILL STAY BETWEEN A LARGE HIGH PRESSURE SYSTEM OVER
THE SOUTHEAST UNITED STATES AND A COMPLEX LOW PRESSURE SYSTEM
CROSSING THE GREAT LAKES. DISTURBANCES PASSING BETWEEN THESE TWO
FEATURES WILL COMBINE WITH HEAT AND HUMIDITY TO RESULT IN
PERIODIC CHANCES OF SHOWERS AND STORMS INTO EARLY WEEK. A COLD
FRONT FINALLY ARRIVES FROM THE NORTH WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 102 AM EDT MONDAY...
MADE SOME MINOR ADJUSTMENTS IN POPS AND TEMPERATURES FOR THIS
MORNING. SHAPED POPS THIS MORNING TOWARDS A BLEND OF RAP AND HRRR.
MORE CHANGES LATER THIS MORNING.
AS OF 920 PM EDT SUNDAY...
MAIN AXIS OF MOISTURE CONVERGENCE LIES FROM MD-CENTRAL WV. MAIN
UPPER IMPULSE THAT WAS OVER TN EARLIER HAS WEAKENED AS HAVE THE
SHOWERS UPSTREAM. OVERNIGHT NOT REALLY SEEING MUCH AS AIRMASS
STABILIZES. WILL KEEP THE HIGHER POPS OVER THE WV MTNS INTO FAR SW
VA...AS ANOTHER WEAK IMPULSE EDGES CLOSER TO THE MTNS BY DAWN.
OTHERWISE EXPECT MID DECK OF CLOUDS TO REMAIN IN THE WESTERN HALF
OF THE CWA WHILE THE EAST CLEARS SOME TOWARD MORNING. OVERALL FOG
THREAT IS PATCHY BUT COULD GET DENSE OUT EAST IF IT CLEARS OUT
ENOUGH. NO OTHER MAJOR CHANGES TO THE FORECAST THROUGH DAWN.
PREVIOUS VALID DISCUSSION...
SHORTWAVES WILL BE EXITING BY EARLY MONDAY LEAVING THE REGION IN DECENT
WEST/SW FLOW ALOFT BUT WITHOUT MUCH FORCING WELL IN ADVANCE OF THE NEXT
UPSTREAM 5H TROF/COLD FRONT TO THE NW. FORECAST SOUNDINGS SHOW QUITE A
DEEP WESTERLY FLOW WHICH RESULTS IN DRYING ALOFT/LOWERING PWATS ESPCLY
WEST MONDAY AFTERNOON AND A LEE TROUGH ACROSS THE PIEDMONT. MOST
GUIDANCE SOLUTIONS SHOW A LACK OF MUCH CONVECTION IN THIS REGIME WITH
ANY FOCUS PROVIDED BY OROGRAPHICS DUE TO WESTERLY CONVERGENCE AND
PERHAPS LATE DAY LOW LEVEL BACKING SE. THUS WILL LEAVE IN SOME LOW POPS
MAINLY WEST AS APPEARS A SUBTLE WAVE ALOFT COULD SNEAK THROUGH AROUND
THE TIME OF MAX HEATING. OTRW EXPECT WEAK LAPSES...LACK OF DEEP
INSTABILITY AND EASTERN DOWNSLOPE TO LIMIT OVERALL COVERAGE WITH MUCH
OF THE DAY LIKELY DRY AFTER EARLY MID DECK/FOG ERODE.
COULD BE ONE OF THE WARMEST DAYS SEEN IN A WHILE WITH 85H TEMPS PUSHING
+21C OVER DECENT DOWNSLOPE AND UNDER AMPLE AFTERNOON SUN. THIS WOULD
SUPPORT SOME MID 90S PIEDMONT...WITH UPPER 80S/LOW 90S BLUE RIDGE...
AND LOW/MID 80S WESTERN ELEVATIONS IF CAN GET A TEMP JUMP AFTER A WARM
START IN THE MORNING.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM EDT SUNDAY...
WITH WEAK HIGH PRESSURE BUILDING IN FROM THE SOUTH...EXPECT TO HEAD
INTO LATE MONDAY NIGHT WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. AS
SUCH...WOULD NOT BE SURPRISED TO SEE PATCHY FOG DEVELOP IN SOME OF
THE MOUNTAIN VALLEYS EARLY MORNING...WHICH WILL BURN OFF QUICKLY
SHORTLY AFTER 9 AM.
DURING TUESDAY AFTERNOON...SHOWER AND THUNDERSTORM ACTIVITY WILL
INCREASE AS AN UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT APPROACH
FROM THE WEST. ACTIVITY WILL START OFF ACROSS THE MOUNTAINS...SPOTTY
AT FIRST DUE TO THE WESTERLY DOWNSLOPE FLOW...AND THEN WILL SPREAD
EAST ACROSS THE PIEDMONT DURING THE EVENING AS THE UPPER LEVEL
ENERGY SHIFTS EAST. LIGHT WINDS AND WARM TEMPERATURES ALOFT WILL
LIMIT INSTABILITY...AND BELIEVE STRONG THUNDERSTORMS WILL BE
ISOLATED AND SHORT LIVED. SHOWER AND THUNDERSTORM ACTIVITY WILL THEN
DIMINISH THROUGH THE NIGHT WITH THE LOSS OF HEATING.
BY WEDNESDAY MORNING...WILL HAVE A WEAK BOUNDARY SITUATED ACROSS OUR
AREA...WHICH WILL EXHIBIT LITTLE MORE THAN A SHIFT IN WIND DIRECTION
FROM ONE SIDE TO THE OTHER AS THE TRULY COOLER AND DRIER AIR WILL
REMAIN WELL NORTH OF OUR AREA. REGARDLESS...THE LOW LEVEL
CONVERGENCE ALONG THE BOUNDARY WILL BE ENOUGH TO TRIGGER ANOTHER
ROUND OF SPOTTY SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND
EVENING. BETTER CHANCES FOR RAINFALL WILL BE FOUND SOUTH OF HIGHWAY
460.
TEMPERATURES HEADING INTO THE MIDDLE OF THE WEEK WILL BE WARMER THAN
NORMAL THANKS TO UPPER LEVEL RIDGING ACROSS THE SOUTHEAST STATES.
LOOK FOR HIGHS TO RANGE FROM THE LOW/MID 80S ACROSS THE MOUNTAINS...
TO THE LOW/MID 90S ACROSS THE SOUTHSIDE. OVERNIGHT LOWS WILL RANGE
FROM THE MID 60S WEST TO THE LOW 70S EAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 345 PM SUNDAY...
A WEAK BOUNDARY WILL REMAIN SITUATED ACROSS THE AREA ON
THURSDAY... PROVIDING THE LOW LEVEL FOCUS FOR SHOWERS AND
THUNDERSTORMS... MAINLY SOUTH OF HIGHWAY 460. ACTIVITY IS EXPECTED
TO REMAIN WIDELY SCATTERED DUE TO THE UPPER LEVEL RIDGE ACROSS THE
SOUTHEAST STATES BUILDING NORTH...HELPING TO LIMIT INSTABILITY.
HIGH PRESSURE WILL PASS ACROSS NEW ENGLAND...ALLOWING WINDS TO
SHIFT EASTERLY THROUGH THE DAY...AND THEN SOUTHEASTERLY DURING THE
EVENING.
AN APPROACHING UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT WILL
TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION ON
FRIDAY AND SATURDAY. THE COLD FRONT WILL MOVE ACROSS OUR AREA
SATURDAY NIGHT...USHERING IN COOLER AND DRIER CANADIAN HIGH
PRESSURE.
TROPICAL AIR WILL REMAIN ACROSS THE AREA THROUGH THE END OF THE
WEEK. AS SUCH...EXPECT WARM AND MUGGY CONDITIONS...WITH
TEMPERATURES HOLDING SLIGHTLY ABOVE NORMAL. COOLER TEMPERATURES
WILL ARRIVE WITH THE COLD FRONT AT THE END OF THE WEEK.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 725 PM EDT SUNDAY...
TOOK SHOWERS OUT OF THE LWB TAF THIS EVENING. STILL CANNOT RULE
OUT A SHOWER INVOF BLF/LWB OVERNIGHT BUT THE CHANCES ARE LIMITED.
OTHERWISE...OVERNIGHT THE OVERALL THREAT OF SHOWERS WILL FADE WITH
A SCT/BKN MID DECK LINGERING. FOG CHANCES ARE GOOD BUT THE MID
DECK SHOULD LIMIT HOW FAR DOWN VSBYS DROP. WILL KEEP MOST TAF
SITES NO WORSE THAN MVFR OVERNIGHT WITH LWB DROPPING OCCASIONALLY
TO IFR AFTER 10Z.
LAST MID LEVEL WAVE WILL PASS TO THE NW BY EARLY MONDAY LEAVING
THE AREA IN BETWEEN THIS FEATURE AND THE NEXT UPSTREAM COLD FRONT.
DEEP WESTERLY FLOW COMBINED WITH LACK OF FOCUS AND DECENT MIXING
SHOULD INHIBIT MUCH CONVECTION DURING MONDAY ESPCLY IF EARLY MID
DECK PERSISTS. THIS SUPPORTS GOOD FLYING CONDITIONS FOR MUCH OF
MONDAY AFTER EARLY LOW CLOUDS/FOG FADE WITH ONLY ISOLATED
CONVECTION LIKELY.
EXTENDED DISCUSSION...
UPPER TROUGH AND ITS ASSOCIATED COLD FRONT WILL APPROACH FROM THE
NORTHWEST TUESDAY WITH SIMILAR ISOLATED SHOWERS/STORMS EXPECTED
DURING THE DAY AHEAD OF THE BOUNDARY. FRONT SETTLES CLOSER TUESDAY
NIGHT INTO WEDNESDAY...WHEN BETTER COVERAGE OF SHRA/TSRA IS
EXPECTED...AND THEN ACROSS THE SOUTH THURSDAY WHERE THE BOUNDARY
STALLS. HOWEVER LOW CONFIDENCE ON THE TIMING AND SOUTHWARD
POSITION OF THE BOUNDARY AT THIS POINT. THUS APPEARS MAINLY VFR
ON TUESDAY...WITH PERIODS OF MVFR WEDNESDAY-THURSDAY IN MORE
ORGANIZED MAINLY AFTERNOON/EVENING CONVECTION...AND MVFR/IFR UNDER
EARLY MORNING FOG IN THE VALLEYS AND WHERE EARLIER HEAVY RAIN
OCCURRED. FRONT WASHES OUT TO THE SOUTH OF THE AREA FRIDAY WITH
MORE DIURNAL NATURE SHOWERS AND STORMS...OTRW VFR.
&&
.EQUIPMENT...
AS OF 730 AM EDT FRIDAY ...
THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WILL
BE OUT OF SERVICE UNTIL FURTHER NOTICE. A PART HAS BEEN BACK-ORDERED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/JH
NEAR TERM...JH/KK/WP
SHORT TERM...NF
LONG TERM...NF
AVIATION...AMS/JH/WP
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
355 AM CDT MON SEP 1 2014
.TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
AREA OF RAIN SHOWERS AND A FEW THUNDERSTORMS OVER SOUTHWEST
WISCONSIN...INTO FAR EASTERN IOWA AND FAR NORTHWEST ILLINOIS...HAS
BEEN SLOWLY WEAKENING OVER THE PAST FEW HOURS. THIS WAS BEING DRIVEN
BY 500 MB VORTICITY MAXIMUM MOVING INTO THE AREA...UPPER DIVERGENCE
WITH RIGHT REAR QUADRANT OF 250 MB JET STREAK...ALONG WITH 850 MB
LOW LEVEL JET. SPC MESOANALYSIS PAGE SHOWING A GOOD AMOUNT OF
CONVECTIVE INHIBITION OVER THE AREA...WHICH MAY BE HELPING WEAKEN
CONVECTION.
STILL...THE ABOVE MAIN FEATURES SHOULD CONTINUE TO BRING SOME
SHOWERS ACROSS THE AREA THROUGH THE MIDDLE MORNING HOURS. THIS IS
SUPPORTED BY THE HRRR AND OTHER MESOSCALE MODELS...THOUGH THEY AREA
SOMEWHAT OVERDONE WITH CURRENT PRECIPITATION TRENDS. THUS...WILL
CONTINUE HIGH POPS THROUGH THE MIDDLE MORNING HOURS FOR SHOWERS AND
ISOLATED STORMS.
MAIN ISSUE WILL BE CONVECTIVE TRENDS THIS AFTERNOON AND EVENING WITH
PASSING COLD FRONT AND SEVERE WEATHER POSSIBILITIES. COLD FRONT WILL
PASS EAST THROUGH THE AREA THIS AFTERNOON...EXITING THE SOUTHEAST BY
MIDDLE TO LATE EVENING. SYNOPTIC MODELS VARY A BIT IN THE TIMING OF
THE FRONT. FRONTOGENESIS RESPONSE WITH FRONT IS WEAK AS IT MOVES
THROUGH THE AREA...THOUGH ELONGATED 500 MB VORTICITY MAXIMUM PUSHES
INTO THE AREA FROM THE WEST. WENT WITH CHANCE POPS FOR THIS
AFTERNOON...AND EVENING IN THE SOUTHEAST...AS THERE IS SOME
UNCERTAINTY WITH THE AREAL COVERAGE OF CONVECTION WITH THE FRONT.
IF MORNING PRECIPITATION CAN MOVE OUT AND CLOUDS BREAK UP THIS
AFTERNOON...SHOULD SEE AT LEAST 1000 TO 1500 J/KG OF MEAN LAYER CAPE
AND AROUND 50 KNOTS OR SO OF DEEP LAYER SHEAR. THIS IS CERTAINLY
SUPPORTIVE OF SEVERE CONVECTION...WITH LARGE HAIL AND DAMAGING WINDS
POSSIBLE. SPC HAS MOST OF THE AREA IN A SLIGHT RISK FOR SEVERE
STORMS THIS AFTERNOON AND EARLY THIS EVENING.
DRIER AIR WORKS INTO THE AREA LATER TONIGHT...BRINGING QUIETER
WEATHER. HIGHS TODAY WILL DEPEND ON AMOUNT OF CLOUDS LINGERING FROM
MORNING PRECIPITATION. WENT WITH UPPER 70S TO LOWER 80S FOR NOW.
LOWS TONIGHT SHOULD DROP INTO THE UPPER 50S TO LOWER/MID 60S.
.TUESDAY AND WEDNESDAY...FORECAST CONFIDENCE...HIGH
IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY AS SURFACE HIGH PRESSURE
SLIDES THROUGH THE AREA. DID ADD A SLIGHT CHANCE FOR
SHOWERS/STORMS IN THE NORTH TUESDAY...AS MODELS NOW IN DECENT
AGREEMENT WITH A WEAK SHORTWAVE PASSING THROUGH. WARM TEMPS WILL
CONTINUE BOTH DAYS WITH HIGHS NEAR TO A FEW DEGREES ABOVE NORMAL.
.WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM
BUMPED POPS UP WEDNESDAY NIGHT...AS MODELS ARE IN PRETTY GOOD
AGREEMENT IN BRINGING STRONG WARM AIR ADVECTION INTO SOUTHERN
WISCONSIN ON THE NOSE OF A 40-50 KT LLJ. LOOKS LIKE A SHORTWAVE
WILL ALSO BE MOVING THROUGH...WHICH SHOULD HELP TO FIRE OFF SOME
SHOWERS/STORMS.
THE PRECIP MAY HANG ON INTO THURSDAY MORNING...WITH MOST MODELS
THEN SHOWING A DRIER AND VERY WARM AFTERNOON IF THE SUN CAN COME
OUT. MODEL 925 MB TEMPS GET UP TO AROUND 25-26C...WHICH WOULD
RESULT IN HIGHS AROUND 90 GIVEN ENOUGH SUN. THROW IN DEWPOINTS IN
THE LOW 70S AND IT COULD END UP BEING AN UNCOMFORTABLE EARLY
SEPTEMBER DAY.
THE COLD FRONT IS EXPECTED TO MOVE THROUGH THURSDAY
NIGHT...BRINGING MORE THUNDERSTORM CHANCES. LINGERED SOME POPS
INTO FRIDAY DUE TO A COUPLE MODELS BEING A BIT SLOWER WITH THE
TIMING OF THE FRONT AND SHORTWAVE. SHOULD SEE HIGH TEMPS BACK DOWN
TO AROUND NORMAL FOR FRIDAY.
.SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM
IT LOOKS COOLER AND DRY SATURDAY AND SUNDAY AS HIGH PRESSURE
SETTLES INTO THE GREAT LAKES REGION. TEMPERATURES WILL LIKELY BE
A FEW DEGREES BELOW NORMAL IF CURRENT MODEL FORECASTS VERIFY.
&&
.AVIATION/12Z TAFS/...
AREA OF SHOWERS AND A FEW STORMS WILL SHIFT EAST NORTHEAST THROUGH
THE AREA INTO THE MIDDLE MORNING HOURS. MAY SEE MVFR VISIBILITIES
AND CEILINGS WITH THESE SHOWERS. GUSTY SOUTH SOUTHWEST WINDS ARE
EXPECTED BY THE AFTERNOON HOURS...WITH GUSTS TO 25 KNOTS AT TIMES.
COLD FRONT WILL PUSH EASTWARD THROUGH TAF SITES BETWEEN 21Z TODAY
AND 03Z TUESDAY. SHOWERS AND STORMS ARE POSSIBLE ALONG AND AHEAD OF
THE FRONT. STRONG/SEVERE STORMS ARE POSSIBLE WITH HAIL AND GUSTY
WINDS. UNCERTAINTY EXISTS WITH THE AREAL COVERAGE OF STORMS...SO
WILL JUST USE VICINITY THUNDER WORDING FOR NOW IN TAFS. MVFR/IFR
VISIBILITIES AND CEILINGS ARE POSSIBLE IN ANY STORMS.
QUIET WEATHER WILL RETURN AFTER THE FRONTAL PASSAGE AND LINGER
THROUGH THE REST OF TONIGHT. LIGHT WINDS AND LINGERING MOISTURE MAY
BRING MVFR/IFR FOG AND CEILINGS TO THE AREA AFTER 06Z TUESDAY.
&&
.MARINE...
CANCELLED MARINE DENSE FOG ADVISORY EARLY...AS INCREASING SOUTH
WINDS SHOULD MIX OUT ANY LINGERING FOG NORTH OF NORTH POINT
LIGHTHOUSE.
SMALL CRAFT ADVISORY CONTINUES FOR THE NEARSHORE WATERS FROM 15Z
UNTIL 23Z TODAY. TIGHT PRESSURE GRADIENT WILL ALLOW FOR GUSTY SOUTH
SOUTHWEST WINDS TO 25 KNOTS AT TIMES. THIS WILL BRING WAVES OF 3 TO
5 FEET TOWARD THE OPEN WATERS. WINDS AND WAVES WILL SUBSIDE BY THIS
EVENING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 6 PM CDT THIS
EVENING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...WOOD
TUESDAY THROUGH SUNDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
308 AM CDT MON SEP 1 2014
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 308 AM CDT MON SEP 1 2014
WATER VAPOR SATELLITE LOOP COUPLED WITH RAP ANALYSIS SHOWS VIGOROUS
MID-LEVEL TROUGH ROTATING THROUGH THE PLAINS TOWARD THE UPPER
MISSISSIPPI RIVER VALLEY. AT THE SURFACE 999MB LOWS WAS OVER WESTERN
ONTARIO WITH A COLD FRONT EXTENDING SOUTHWARD THROUGH MN/NW
IA/CENTRAL NEB. RADAR WAS LIT UP WITH SHOWERS/THUNDERSTORMS ACROSS
EASTERN MN INTO THE FORECAST AREA AHEAD OF THE MID-LEVEL WAVE AND
SURFACE COLD FRONT. OTHERWISE...TEMPERATURES ACROSS THE AREA EARLY
THIS MORNING WERE IN THE 60S.
LOOK FOR THE SURFACE COLD FRONT AND ASSOCIATED CONVECTION TO
CONTINUE PUSHING EAST ACROSS THE AREA THIS MORNING WITH THE BULK OF
THE RAIN EXITING EAST BY LATE MORNING. KEPT LINGERING AND
DIMINISHING CHANCES GOING HOWEVER INTO THE AFTERNOON AS THE MID-
LEVEL TROUGH/COLD AIR ALOFT POSSIBLY POPPING A FEW INSTABILITY
SHOWERS AND THUNDERSTORMS. NOT EXPECTING ANY SEVERE THREAT AS BEST
CAPE AND WIND SHEAR SHIFT EAST/SOUTHEAST OF THE AREA.
FOR TONIGHT...WILL SEE ANOTHER WEAK MID-LEVEL WAVE ROTATE TOWARD THE
AREA FROM THE NORTHERN PLAINS. NAM SHOWING A DECENT SHOT OF 700-
300MB PVA MOVING IN MAINLY WEST OF THE MISSISSIPPI RIVER AFTER
MIDNIGHT WITH BUFKIT SHOWING INSTABILITY/MOISTURE MAINLY CONFINED
ABOVE 800MB. KEPT A SMALL-END CHANCE OF SHOWERS/ISOLATED WEST OF THE
MISSISSIPPI AFTER MIDNIGHT BASED ON THIS SIGNAL. OVERNIGHT LOWS ARE
EXPECTED TO FALL INTO THE 50S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 308 AM CDT MON SEP 1 2014
A SMALL CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO
TUESDAY MAINLY NORTH OF I-94 AS THE WEAK MID-LEVEL TROUGH ROTATES
ACROSS THE FORECAST AREA. PLAN ON HIGHS RANGING FROM THE MIDDLE 70S
ACROSS NORTH CENTRAL WI...TO THE UPPER 70S/LOWER 80S ELSEWHERE.
SURFACE CYCLOGENESIS OVER THE NORTHERN PLAINS WILL PUSH A WARM FRONT
TOWARD THE AREA WEDNESDAY/WEDNESDAY NIGHT. ALL MODELS SHOW
INCREASING 850MB MOISTURE TRANSPORT/WARM AIR ADVECTION NOSING INTO
THE AREA WITH THE FRONT FOR INCREASING COVERAGE OF THUNDERSTORMS.
PRECIPITABLE WATER VALUES PUSHING 1.9 INCHES BY THURSDAY MORNING WITH
WARM CLOUD DEPTH LAYERS INCREASING INTO THE 4-4.5KM RANGE. BASED ON
THIS SIGNAL...WILL HAVE TO WATCH FOR A HEAVY RAINFALL POTENTIAL
ALONG WITH OTHER SEVERE THREATS AS WELL AS CAPE AND BULK SHEAR
INCREASE ALONG THE WARM FRONT. AT THIS POINT...MODELS SHOWING HIGHER
SEVERE POTENTIAL STAYING WEST OF THE MISSISSIPPI RIVER IN MORE
FAVORABLE CAPE/SHEAR ENVIRONMENT. WILL HAVE TO KEEP A CLOSE ON THIS
OVER THE NEXT COUPLE DAYS. LOOK FOR HIGHS ON WEDNESDAY TO TOP OFF IN
THE UPPER 70S TO MIDDLE 80S WITH DEW POINTS CREEPING UP INTO THE 65-
70 DEGREE RANGE.
THUNDERSTORM CHANCES CONTINUE THURSDAY INTO THURSDAY NIGHT AS THE
LOW PULLS NORTHEAST INTO ONTARIO CANADA...PUSHING A COLD FRONT
THROUGH THE AREA. THURSDAY WILL HAVE TO BE WATCHED CLOSELY AS WELL
FOR SEVERE POTENTIAL AS THE GFS IS SHOWING 0-6KM BULK SHEAR OF 30-
50KT COUPLED WITH MUCAPE POOL OF 2500-4500J/KG. HIGHS ON THURSDAY
AHEAD OF THE COLD FRONT ARE EXPECTED TO TOP OFF WELL INTO THE 80S
WITH DEW POINTS IN THE 70-75 DEGREE RANGE.
DRIER/COOLER AIR FILTERS INTO THE AREA FRIDAY AND INTO THE WEEKEND
AS CANADIAN HIGH PRESSURE BUILD INTO THE REGION. PLAN ON
TEMPERATURES BY THIS WEEKEND TO FEEL A BIT MORE LIKE FALL WITH HIGHS
IN THE 60S/LOWER 70S AND LOWS IN THE 50S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1144 PM CDT SUN AUG 31 2014
01.0430Z RADAR SHOWS A LARGE SWATH OF MODERATE TO HEAVY RAIN WITH
EMBEDDED THUNDER ALONG AND WEST OF THE MISSISSIPPI RIVER. BACK
EDGE OF THIS PRECIPITATION IS JUST WEST OF KRST SUCH THAT DRY
CONDITIONS ARE EXPECTED NO LATER THAN 01.07Z AT KRST AND 01.09Z AT
KLSE. WITH SATURATED NEAR SURFACE LAYER...EXPECT CEILINGS TO LOWER
OVERNIGHT WITH MVFR VISIBILITY IN MIST. CONDITIONS EXPECTED TO
SLOWLY IMPROVE LABOR DAY MORNING...BUT REMAIN MVFR THROUGH MUCH OF
THE DAY...FINALLY IMPROVING TO VFR BY 02.00Z. WINDS WILL SHIFT TO
THE NORTHWEST AFTER FRONTAL PASSAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...ROGERS
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1154 PM CDT SUN AUG 31 2014
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
AND NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 1148 PM CDT SUN AUG 31 2014
HAVE CONTINUED TO HIT LOWER VISBY AT LAKESHORE WITH SPS AS NOT
WIDESPREAD ENOUGH TO GO WITH ADVISORY. IS STARTING TO IMPROVE IN
MANITOWOC AND WILL CONTIUE TO IMPROVE NEXT HOUR OR SO. WILL BE
WATCHING AREA OF STORMS/SHOWERS MOVING THROUGH SOUTHERN WI. WINDS
AT LEAD EDGE STILL RATHER STRONG.
&&
.SYNOPSIS...
ISSUED AT 218 PM CDT SUN AUG 31 2014
WARM AND RATHER HUMID WITH SHOWERS AND THUNDERSTORMS AT TIMES FOR
THE REST OF THE HOLIDAY WEEKEND AND THROUGH THE UPCOMING WORK
WEEK.
STG SUBTROPICAL RIDGE ACRS THE SRN CONUS WL EXPAND NWD A BIT AS
SOMEWHAT PROGRESSIVE BAND OF WESTERLIES GRADUALLY RECEDES NWD
DURING THE PERIOD. NOTHING SPECIAL ABOUT THIS PATTERN FOR THIS
TIME OF YEAR...AS THE WESTERLIES ARE TYPICALLY STRONGER THAN
DURING THE MIDDLE SUMMER...BUT ARE STILL USUALLY CENTERED N OF THE
AREA.
THE PRIMARY FRONTAL ZONE SEPARATING WARM AND VERY MOIST TROPICAL
AIR TO THE S FM COOLER AND DRIER CANADIAN AIR TO THE N WL REMAIN
STETCHED OUT W-E ALONG THE SRN EDGE OF THE MAIN WESTERLIES...AND
CLOSE TO THE FCST AREA MUCH OF THE TIME. THIS WL RESULT IN
SEVERAL OPPORTUNITIES FOR PCPN...LIKELY RESULTING IN ABV NORMAL
AMNTS. TEMPS ARE EXPECTED TO REMAIN AOA NORMAL FOR MUCH OF THE
FCST PERIOD BEFORE DROPPING BACK CLOSE TO NORMAL LATE. IT WILL
ALSO BE HUMID AT TIMES.
&&
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 218 PM CDT SUN AUG 31 2014
THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW
PRESSURE MOVING NORTHEAST OVER FAR NORTHWEST MINNESOTA AND A COLD
FRONT MOVING EASTWARD FROM THE LOW TO THE CENTRAL GREAT PLAINS.
STORMS HAVE BEGUN TO FIRE ALONG THE FRONT OVER SOUTH CENTRAL
MINNESOTA...BUT THE ATMOSPHERE IS STRUGGLING TO DESTABILIZE DUE IN
PART TO A PRONOUNCED CAP AND DRY AIR ON THE 18Z MINNEAPOLIS
SOUNDING. HOWEVER...AS A SHORTWAVE OVER NEBRASKA MOVES INTO THE
NORTHERN MISSISSIPPI VALLEY...THE CAP IS EXPECTED TO WEAKEN LATE
THIS AFTERNOON THAT WILL RESULT IN A FAVORABLE ENVIRONMENT FOR
SEVERE STORMS. THESE STORMS COULD MOVE INTO NORTH-CENTRAL WISCONSIN
LATER THIS EVENING. THE MAIN SHORTWAVE IS MOVING EAST OVER EASTERN
WYOMING AND ANTICIPATED TO ARRIVE INTO WISCONSIN LATE TONIGHT INTO
MONDAY MORNING...ALONG WITH THE COLD FRONT. THUNDERSTORM TIMING AND
IMPACTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...A COLD FRONT WILL SLOWLY MOVE ACROSS THE NORTHERN
MISSISSIPPI VALLEY AS IT WAITS FOR A SHORTWAVE OVER WYOMING TO GIVE
IT A FORWARD PUSH. ASSUMING STRONG TO SEVERE CONVECTION AHEAD OF
THE FRONT DEVELOPS AS PLANNED LATER THIS AFTERNOON INTO THIS
EVENING...GUIDANCE SUGGESTS THIS CONVECTION WILL MAKE A RUN AT
NORTH-CENTRAL WISCONSIN LATE THIS EVENING...THOUGH WILL BE WEAKENING
AS DIURNAL INSTABILITY IS LOST. MODELS SUGGEST AROUND 1000 J/KG OF
ELEVATED CAPE WILL BE PRESENT AS THIS CONVECTION APPROACHES THE
NORTHWEST FORECAST AREA SO NOT OUT OF THE QUESTION THAT A FEW STRONG
STORMS COULD REACH NORTH-CENTRAL WISCONSIN. AN ISOLATED SEVERE
STORM CANNOT BE RULED OUT...MAINLY FOR DAMAGING WINDS AND LARGE
HAIL. WOULDNT BE SURPRISE TO SEE A FEW HOUR BREAK OVERNIGHT BETWEEN
THIS CONVECTION AS IT WEAKENS/LIFTS TO THE NORTHEAST...AND A MORE
WIDESPREAD AREA OF SHOWERS AND THUNDERSTORMS AHEAD OF THE MAIN
SHORTWAVE WHICH WILL MOVE INTO THE NORTHERN MISSISSIPPI VALLEY BY
12Z. THIS AREA OF PRECIP SHOULD MOVE ACROSS CENTRAL AND
NORTH-CENTRAL WI LATE TONIGHT. ELEVATED CAPES LOOK TO BE APPROX 500
J/KG SO NOT ANTICIPATING SEVERE CONVECTION. LOWS MAINLY IN THE
MIDDLE 60S.
MONDAY...THE SHORTWAVE TROUGH WILL LIFT NORTHEAST ACROSS WISCONSIN
MONDAY MORNING...DRIVING THE AREA OF SHOWERS AND THUNDERSTORMS
ACROSS NORTH-CENTRAL AND NORTHEAST WISCONSIN. THE HEAVIEST RAINFALL
LOOKS TO OCCUR OVER CENTRAL AND NORTH-CENTRAL WISCONSIN WITH THIS
EVENT AND COULD SEE AN INCH TO 1.50 INCHES IF CONVECTION REACHES
INTO THIS AREA THIS EVENING. WITH PRECIPITATION OCCURRING DURING
THE MORNING AND THE SHORTWAVE LIFTING NORTHEAST OF THE AREA IN THE
AFTERNOON...SEEMS LIKE AN AWFULLY SMALL TIME PERIOD FOR
REDEVELOPMENT OF STORMS ALONG THE COLD FRONT OVER NORTHEAST
WISCONSIN. THE BEST BET MAY BE TO HAVE STORMS CONTINUOUSLY REFIRE
ALONG THE TAIL OF THE SHORTWAVE...BUT THIS ADMITTEDLY SEEMS LIKE
A SMALL CHANCE SINCE THE ATMOSPHERE WILL HAVE BEEN WORKED OVER
BY THIS TIME...AND PRECIPITATION WILL HAVE SQUASHED SURFACE BASED
INSTABILITY. AS A RESULT...SPC HAS SHIFTED THE SLIGHT RISK OF
SEVERE WEATHER TO THE SOUTH AND EAST OF THE FORECAST AREA AND THIS
SEEMS REASONABLE. WILL MENTION THE CHANCE OF GUSTY WINDS AND SMALL
HAIL BUT LEAVE THE THREAT OF SEVERE WEATHER OUT OF THE HWO.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 218 PM CDT SUN AUG 31 2014
SOME LINGERING PCPN WL BE POSSIBLE MON EVENING...MAINLY OVER E-C
WI. CARRIED CHC POPS INTO THE EARLY EVENING. WHILE ISOLD SHRA
COULD LINGER WELL INTO THE NGT...THE MAIN POOL OF INSTABILITY WL
BE WELL S BY THEN...SO OPTED TO GO WITH A DRY FCST AFTER MIDNIGHT.
LATER SHIFTS MAY NEED TO TAKE ANOTHER LOOK AT THAT.
THERE ARE PROS AND CONS FOR PCPN CHCS TUE. ON ONE HAND...UPR TROF
WL STILL BE ACRS THE AREA DURING THE MORNING...AND WNWLY UPR FLOW
WL KEEP MODEST MID-LVL LAPSE RATES ACRS THE RGN. ON THE OTHER...
UPR HEIGHTS WL BE RISING AS THE TROF SHIFTS E...AND QG FORCING
WL BE FAVORING SUBSIDENCE. OPTED TO KEEP FAIRLY LOW POPS...BUT
WENT WITH ISOLD SHRA ACRS ALL BUT THE FAR SRN PART OF THE AREA.
PCPN UNLIKELY TO BE A BIG DEAL...BUT CONFIDENCE IN TOTALLY DRY DAY
ISN/T THAT GREAT EITHER.
UPR HEIGHTS SHOULD CONT TO RISE TUE NGT/WED. STAYED DRY TUE NGT...
BUT N-C WI WL BE CLOSE ENOUGH TO THE RETURN FLOW TO JUSTIFY
HAVING A CHC OF TSRA WED.
WENT WITH A BLEND OF TOP PERFORING GUIDANCE PRODUCTS FOR TEMPS...
WHICH WERE DOMINATED BY THE ECMWF AND IT/S MOS AND BIAS-CORRECTED
DERIVATIVES.
NO SIG CHGS NEED TO BROAD-BASED EXTENDED FCST INITIALIZATION
GRIDS.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1148 PM CDT SUN AUG 31 2014
IMPROVING CONDITIONS AT LAKESHORE AS WINDS INCREASE OVERNIGHT.
SHOWERS AND STROMS AHEAD OF A COLD FRONT WILL MOVE ACROSS THE
REGION LATE TONIGHT INTO MONDAY...SCATTERED MVFR CIGS AND
VSBYS...LOCALLY IFR...WILL DEVELOP DUE TO HEAVY RAIN AND POSSIBLE
THUNDERSTORMS. SOME STORMS MAY CONTAIN STRONG GUSTY WINDS AS THEY
MOVE INTO CENTRAL AND NORTH-CENTRAL WISCONSIN OVERNIGHT. HAVE
ADDED SOME LLWS AS LOW LEVEL JET STRENGTHENS OVERNIGHT. IMPROVING
CONDITIONS EXPECTED BY MON AFTN. &&
.GRB WATCHES/WARNINGS/ADVISORIES...
BEACH HAZARDS STATEMENT FROM 8 AM CDT MONDAY THROUGH MONDAY
EVENING FOR WIZ022-040-050.
&&
$$
UPDATE.........TE
SYNOPSIS.......SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......SKOWRONSKI
AVIATION.......TE
AREA FORECAST DISCUSSION
NWS ALBANY NY
1034 AM EDT MON SEP 1 2014
.SYNOPSIS...
HIGH PRESSURE WILL BRING A RETURN TO SOME SUNSHINE AND
VERY WARM TEMPERATURES TODAY. IT WILL REMAIN HUMID...AS
TEMPERATURES COULD TURN EVEN HOTTER ON TUESDAY. A COLD FRONT WILL
APPROACH THE REGION LATE TUESDAY INTO TUESDAY EVENING BRINGING
NUMEROUS SHOWERS AND THUNDERSTORMS...AND SLIGHTLY COOLER AND
NOTICEABLY DRIER AIR WILL FOLLOW ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1034 AM EDT...A WEAK SFC RIDGE WILL BUILD IN OVER NY AND NEW
ENGLAND TODAY...AS THE WATER VAPOR LOOP SHOWS SOME DRYING ALOFT
WITH THE PASSAGE OF A MID-LEVEL SHORT WAVE OVER NRN NEW ENGLAND.
MID LEVEL HEIGHTS ARE BUILDING UPSTREAM OVER SE CANADA...W-CNTRL NY
AND PA THIS MORNING.
THE LATEST 3-KM HRRR SHOWS VERY LITTLE CONVECTIVE ACTIVITY THIS PM
WITH A MID LEVEL CAP SETTING UP...AND A LACK OF A GOOD FOCUSING
MECHANISM. THE BEST CHC FOR AN ISOLD-SCT POP UP SHOWER OR
THUNDERSTORM IS SOUTH OF THE CAPITAL REGION. SBCAPE VALUES WILL BE
IN THE 1000-1500 J/KG RANGE THERE...AND THE DIFFERENTIAL HEATING
BTWN THE MTNS/VALLEYS COULD ALLOW FOR SOME POP-UP ACTIVITY. ISOLD-
SCT SHOWERS WITH AN ISOLD THUNDERSTORM WERE ONLY KEPT IN THE FCST
SOUTH OF THE CAPITAL REGION FOR MAINLY THE MID TO LATE PM.
HIGHS TODAY WILL GENERALLY BE IN THE LOWER TO M80S...WITH A FEW
U80S IN THE MID HUDSON VALLEY/NW CT. EXPECT U70S TO L80S OVER THE
MTNS. IT WILL REMAIN VERY HUMIDITY WITH SFC DEWPTS IN THE M60S TO
L70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
ANY LEFTOVER CONVECTION WILL END SHORTLY AFTER SUNSET...LEAVING US
WITH A RAINFREE BUT MUGGY OVERNIGHT. MORE PATCHES OR EVEN AREAS OF
FOG WILL FORM AFTER MIDNIGHT. LOWS WILL BE IN THE 60S...CLOSE TO 70
IN THE TRI-CITY REGION.
TUESDAY...A SOUTH TO SOUTHWEST WIND WILL INCREASE A LITTLE AHEAD OF
COLD FRONT APPROACHING FROM THE NORTHWEST. H850 TEMPERATURES LOOK TO
RAMP UP TO ABOUT +18C. WITH ANY MORNING AND MIDDAY
SUNSHINE...TEMPERATURES LOOK TO GO EVEN A LITTLE HIGHER THAN
TODAY...80S...TO NEAR 90 JUST SOUTH OF THE CAPITAL REGION. THE ONLY
EXCEPTION WILL BE THE ADIRONDACK PARK WHERE MORE CLOUDS AND
SHOWERS/THUNDERSTORMS...ASSOCIATED WITH AN ADVANCING COLD
FRONT...WILL KEEP TEMPERATURES HELD TO THE UPPER 70S.
APPARENT TEMPERATURES ON TUESDAY AFTERNOON ARE FORECASTED TO REACH
THE UPPER 90S IN PORTIONS OF THE MID HUDSON VALLEY...GENERALLY LOWER
TO MID MOST OTHER VALLEY AREAS...80S OVER THE HIGHER TERRAIN.
THE AFOREMENTIONED COLD FRONT (AND PERHAPS A PRE-FRONTAL TROUGH)
WILL ADVANCE OVER MOST OUR REGION DURING THE AFTERNOON AND EARLY
EVENING HOURS. THIS FRONT PRODUCED QUITE OF BIT OF THUNDERSTORM WIND
DAMAGE AND SOME LARGE HAIL IN THE MID WEST.
SHOWERS AND THUNDERSTORMS WILL LIKELY DEVELOP ALONG OR A LITTLE
AHEAD OF THESE FEATURES. IT DOES APPEAR THE BEST FORCING WILL
ACTUALLY LIFT INTO CANADA AS THE RIGHT ENTRANCE REGION OF THE UPPER
LEVEL JET MOVES THAT WAY.
NEVERTHELESS THERE SHOULD BE PLENTY OF INSTABILITY...LOW LEVEL
CONVERGENCE (ASSOCIATED WITH THE FRONT)...AND MOISTURE...TO GENERATE
SHOWERS AND STORMS. AN ORGANIZED LINE COULD EVEN FORM. FOR
NOW...SINCE WE ARE NOT OFFICIALLY OUTLOOKED BY SPC...WE WILL ONLY
MENTION POSSIBLE HEAVY RAINFALL WITH THE THUNDERSTORMS ON TUESDAY
SINCE PWAT VALUES WILL ONCE AGAIN INCREASE TO 2 INCHES OR
BETTER...EXCEEDING 70% OF NORMAL AMOUNTS FOR EARLY SEPTEMBER.
SHOWERS AND THUNDERSTORMS COULD LINGER INTO TUESDAY EVENING...BUT AT
THIS POINT...THE FRONT LOOKS TO MOVE FAIRLY QUICKLY EAST AND BE
REPLACED BY SOMEWHAT DRIER AND COOLER AIR. THE THUNDERSTORM THREAT
LOOKS TO WANE BY MIDNIGHT. TEMPERATURES OVERNIGHT TUESDAY LOOK TO
FALL BACK INTO THE MID 50S TO THE NORTHWEST OF ALBANY...60-65
FURTHER SOUTH.
AN AIRMASS ORIGINATING FROM SOUTHERN CANADA WILL BRING A GUSTY
NORTHWEST BREEZE WHICH WILL DROP DEWPOINTS BACK INTO THE 50S ON
WEDNESDAY. HIGH TEMPERATURES WILL ACTUALLY STILL BE SLIGHTLY ABOVE
NORMAL...RANGING FROM THE MID 70S TO MID 80S...LOCALLY AROUND 80 IN
ALBANY. HOWEVER...WITH THE BREEZE AND LOWER HUMIDITY...IT WILL BE
MORE PLEASANT OUTDOORS.
A MAINLY CLEAR NIGHT ON WEDNESDAY AND LIGHT WIND WILL ALLOW
TEMPERATURES SETTLE BACK INTO THE 50S ACROSS MUCH OF OUR
AREA...EXCEPT MID OR UPPER 40S OVER PORTIONS OF THE ADIRONDACKS AND
SOUTHERN GREENS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE LONG TERM PERIOD STARTS OUT WITH HIGH PRESSURE IN CONTROL AND
INCREASINGLY WARM TEMPS AS A SOUTHWESTERLY FLOW TAKES HOLD ON THE
WESTERN SIDE OF A LARGE HIGH PRESSURE THAT WILL BE SLIDING OFF THE
COAST. MAINLY DRY WEATHER IS FORECAST WITH ONLY A SLIGHT CHANCE OF
SHOWERS/TSTMS LATER FRIDAY AFTN AS A COLD APPROACHES FROM THE GREAT
LAKES. HIGHS THURSDAY WILL BE IN THE UPPER 70S TO MID 80S...AND A
COUPLE OF DEGREES WARMER ON FRIDAY. LOWS THURSDAY NIGHT IN THE MID
50S TO LOWER 60S.
THE COLD FRONT WILL MOVE INTO THE REGION AT THE START OF THE WEEKEND
ALONG WITH THE THREAT OF SHOWERS/TSTMS. SOME MODEL DISAGREEMENT AS
TO HOW FAST THIS FRONT WILL MOVE THROUGH. THE CANADIAN MODEL IS THE
FASTEST OF ALL AND ACTUALLY HAS THE FRONT SOUTH AND EAST OF THE
REGION BY SATURDAY MORNING WITH PCPN ENDING. ECMWF LINGERS THE FRONT
OVER THE REGION THROUGH THE WEEKEND WITH A CHANCE OF SHOWERS/TSTMS
THROUGH MUCH OF SUNDAY. THE GFS IS IN BETWEEN WITH THE FRONT SOUTH
AND EAST OF THE REGION BY SATURDAY AFTERNOON WITH THE THREAT OF
SHOWERS CONFINED TO FRIDAY NIGHT AND EARLY SATURDAY. CANADIAN SEEMS
TOO FAST...SO TAKEN A COMPROMISE BETWEEN THE GFS AND ECMWF WITH A
CHANCE OF SHOWERS FORECAST FRIDAY NIGHT THROUGH SATURDAY
NIGHT...THEN CLEARING AND COOLER ON SUNDAY AS A LARGE CANADIAN HIGH
PRESSURE SYSTEM BUILDS INTO THE REGION. LOWS FRIDAY NIGHT WILL BE IN
THE UPPER 50S TO MID 60S. HIGHS SATURDAY IN THE 70S TO LOWER 80S.
LOWS SATURDAY NIGHT IN THE UPPER 40S AND 50S. HIGHS SUNDAY IN THE
MID 60S TO MID 70S.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
MVFR TO OCCASIONAL IFR CONDITIONS DUE TO FOG/STRATUS WILL PERSIST AT
THE KGFL/KALB/KPSF TAF SITES TO 12Z-14Z THIS MORNING...WITH VFR TO
OCCASIONALLY MVFR VSBYS AT KPOU THROUGH 14Z. AFTER AROUND
13Z...VFR CONDITIONS WILL RETURN TO ALL THE TAF SITES. LINGERING
LOW LEVEL MOISTURE AND SOME WEAK INSTABILITY COULD RESULT IN
ISOLATED SHOWERS/TSTMS THIS AFTN...SO HAVE INCLUDED VCSH IN THE
TAF FORECASTS FROM AROUND 19Z THRU 00Z TUESDAY. FOR
TONIGHT...EXPECT MAINLY CLEAR SKIES AND LIGHT WINDS...SO FOG
FORMATION IS LIKELY AGAIN. HAVE FORECAST CONDITIONS TO LOWER TO
MVFR/IFR AT ALL THE TAF SITES AROUND AND AFTER MIDNIGHT.
WINDS WILL BE CALM OR LIGHT AND VARIABLE EARLY THIS MORNING...THEN
BECOME SOUTH OR SOUTHWEST AT 8 KTS OR LESS DURING THE REST OF THE
DAY. THE WINDS WILL BECOME LIGHT AND VARIABLE OR CALM AGAIN TONIGHT.
OUTLOOK...
TUESDAY: HIGH OPERATIONAL IMPACT. LIKELY PM SHRA...TSRA.
TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHC SHRA...TSRA.
WEDNESDAY THROUGH FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
TODAY WILL FEATURE PATCHES OF FOG TO START THE DAY. A STRAY SHOWER
OR THUNDERSTORM IS POSSIBLE THIS AFTERNOON...MAINLY SOUTH OF
ALBANY...BUT THAT WILL BE EXCEPTION RATHER THAN THE RULE.
WITH ONLY A LIGHT WIND...MAINLY OUT OF THE SOUTHWEST...RH VALUES
WILL REMAIN ELEVATED TODAY...ONLY DROPPING TO THE 55-65 PERCENT
RANGE. IT WILL BE VERY WARM WITH A GOOD DEAL OF SUNSHINE (ONCE THE
FOG BURNS OFF).
LOOK FOR A FULL RECOVERY TONIGHT WITH MORE FOG AND RH VALUES NEAR
100 PERCENT.
TUESDAY WILL BE VERY WARM ONCE MORE. SOME SUNSHINE SHOULD BURN THE
FOG AWAY PERHAPS A LITTLE QUICKER THAN TODAY. BY AFTERNOON
THOUGH...A COLD FRONT WILL APPROACH...LIKELY TRIGGERING ANOTHER
ROUND OF SHOWERS AND THUNDERSTORMS...SOME OF WHICH COULD CONTAIN
TORRENTIAL RAINFALL.
DRIER AND SLIGHTLY COOLER AIR WILL FILTER IN BEHIND THE COLD FRONT
LATE TUESDAY NIGHT AND HOLD FOR THE REMAINDER OF THE WEEK.
&&
.HYDROLOGY...
THERE WERE POCKETS OF ONE INCH OR MORE OF RAINFALL...MAINLY NORTH
AND SOUTH OF THE CAPITAL REGION ON SUNDAY. MOST AREAS HOWEVER
RECEIVED WELL UNDER AN INCH OF RAINFALL. THERE WAS LITTLE IF ANY
IMPACT ON MAIN STEM RIVERS SINCE WE HAD BEEN DRY BEFORE THIS RAIN
MOVED IN.
ANY SHOWERS OR THUNDERSTORMS TODAY WILL BE WIDELY SCATTERED AND
SHOULD HAVE NO IMPACT ON OUR WATERSHED.
TUESDAY COULD BE A DIFFERENT STORY. WE EXPECT NUMEROUS SHOWERS AND
THUNDERSTORMS AFTERNOON AND EVENING. AVERAGE BASIN RAINFALL LOOKS TO
BE MAINLY UNDER AN INCH SO ONCE AGAIN WE DO NOT EXPECT MANY IF ANY
RISES ON THE RIVERS. HOWEVER...RAINFALL COULD BE LOCALLY HEAVY
PRODUCING THE USUAL PONDING PROBLEMS.
DRIER WEATHER RETURNS BY WEDNESDAY...LASTING THROUGH THE REMAINDER
OF THE WORKWEEK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV/WASULA
NEAR TERM...WASULA
SHORT TERM...HWJIV
LONG TERM...GJM
AVIATION...GJM/WASULA
FIRE WEATHER...HWJIV
HYDROLOGY...HWJIV
AREA FORECAST DISCUSSION
NWS MIAMI FL
1021 AM EDT MON SEP 1 2014
.UPDATE...
THE LATEST WATER VAPOR IMAGERY INDICATES THE MID TO UPPER LEVEL
TROUGH CONTINUES TO RETROGRADE TO THE SOUTHWEST AND IS ENTERING
THE NORTHWEST BAHAMAS. THIS IS BRINGING IN SOME DRIER MID TO UPPER
LEVEL AIR INTO SOUTH FLORIDA AND ADJACENT WATERS THIS MORNING.
RECENT RADAR RETURNS INDICATE ISOLATED SHOWER ACTIVITY MAINLY
ACROSS THE ATLANTIC WATERS. MINOR UPDATES WERE DONE TO THE SHORT
TERM FORECAST TO REFLECT THE CURRENT CONDITIONS. BUT AS THE
AFOREMENTIONED TROUGH CONTINUES TO MOVE TO THE SOUTHWEST AND INTO
THE REGIONAL ATLANTIC WATERS...THAT WILL LIKELY ALLOW FOR SOME
POTENTIAL FOR CONVECTION. THERE IS CURRENTLY ACTIVE CONVECTION IN
THE NORTHWEST BAHAMAS ISLANDS. SO THE FORECAST REFLECTS SCATTERED
SHOWER/THUNDERSTORM ACTIVITY POSSIBLE OVER THE ATLANTIC WATERS
AND EAST COAST METRO AREAS LATER THIS AFTERNOON WITH GREATER
COVERAGE EXPECTED ACROSS THE WESTERN PENINSULA LATE THIS AFTERNOON
WHERE THE SURFACE CONVERGENCE WILL BE MOST DOMINANT. SO OVERALL NO
SIGNIFICANT CHANGES FROM PREVIOUS FORECAST OR SYNOPTIC REASONING
EXCEPT FOR THE VERY SHORT TERM.
60
&&
.PREV DISCUSSION... /ISSUED 728 AM EDT MON SEP 1 2014/
AVIATION...
MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST WITH A
MODERATE EAST WIND FLOW. ANTICIPATED TSRA DEVELOPMENT WILL BE OVER
THE INTERIOR WITH A WESTWARD PROPAGATION. AT THIS TIME, PLACED A
VCTS IN THE KAPF TAF AFT 19Z AND THEY COULD HAVE A BRIEF MVFR OR
EVEN IFR CIG/VSBY THROUGH THE AFTERNOON. EAST FLOW WILL PREVENT A
SEA BREEZE ALONG THE SOUTHWEST COAST BUT WIND IS LIKELY TO VEER TO
THE SSE AS IT TRIES TO FORM.
KOB
PREV DISCUSSION... /ISSUED 329 AM EDT MON SEP 1 2014/
HIGHLIGHTS...
* MODERATE RISK OF RIP CURRENTS ATLANTIC BEACHES
* SLIGHT TSTORM CHANCE EAST COAST, BETTER CHANCE GULF COAST TODAY
* STORMIER PATTERN MID-LATE WEEK; STRONG STORMS POSSIBLE
DISCUSSION...
THE WEATHER PATTERN ON THIS LABOR DAY WILL REMAIN
MOSTLY UNCHANGED FROM YESTERDAY. RIDGE AXIS WILL REMAIN OVER NORTH
FLORIDA, MAINTAINING AN EASTERLY WIND FLOW LOCALLY WITH CONVECTIVE
FOCUS ALONG THE GULF COAST IN THE AFTERNOON. LOW LEVEL WINDS WILL
BE STRONG ENOUGH TO DISALLOW A FULL GULF SEA BREEZE FROM
DEVELOPING, BUT SOME VEERING OF THE WIND FIELD IS EXPECTEDTHERE
WHICH AGAIN WILL LEAD TO ENOUGH CONVERGENCE TO SPARK SOME TSTORM
DEVELOPMENT. ACROSS THE EAST COAST, HRRR SHOWS A SCENARIO SIMILAR
TO YESTERDAY WITH QUICK PASSING SHOWERS DEVELOPING. CANNOT RULE
OUT TSTORMS EAST COAST BUT CONVERGENCE WILL BE LACKING SO COVERAGE
WOULD BE ISOLATED AT BEST.
LIKE YESTERDAY, A LIMITING FACTOR FOR MORE ACTIVE TSTORMS IS THE
LACK OF A FULL FLEDGED ONSHORE GULF SEA BREEZE. HOWEVER, CANNOT
RULE OUT A STRONG TSTORM OR TWO GIVEN SOME CONVERGENCE ALONG WITH
THE INSTABILITY AND CONTINUED DRY AIR ALOFT. WIND GUSTS OF 40-50
MPH IS THE PRIMARY THREAT.
A DEEP LAYERED TROUGH EAST OF THE BAHAMAS IS SHOWN BY THE GLOBAL
MODELS TO MOVE WEST AND ACROSS SOUTH FLORIDA WED NIGHT-THU. THIS
WILL BE ASSOCIATED WITH COOLING ALOFT ALONG WITH INCREASING
MOISTURE, SPELLING A STORMIER PERIOD MID WEEK AND EVEN INTO LATE
WEEK AS HIGHER INSTABILITY REMAINS. POPS ACCORDINGLY SHOW AN
UPWARD TREND MID-LATE WEEK. COULD SEE SOME STRONG STORMS ANYWHERE
BEGINNING WED THROUGH LATE WEEK DUE TO THE COLD AIR ALOFT AND
TROUGH PASSAGE, THOUGH MORE CLOUDINESS WOULD BE A LIMITING FACTOR.
/GREGORIA
AVIATION...
HIGH PRESSURE WILL SLOWLY WEAKEN OVER THE SOUTHEASTERN UNITED
STATES TODAY WHICH IN TURN WILL KEEP A EASTERLY WIND FLOW OF
AROUND 5 KNOTS THROUGH EARLY THIS MORNING AT ALL OF THE TAF SITES.
THE WIND DIRECTION WILL REMAIN EASTERLY AFTER 14Z TODAY BUT
INCREASE TO AROUND 10 KNOTS OVER ALL OF THE TAF SITES.
THE WEATHER SHOULD REMAIN DRY THROUGH THE EARLY MORNING HOURS BEFORE
SOME SHOWERS WORKS INTO THE EAST COAST TAF SITES AFTER 14Z.
SO WILL PUT IN VCSH AFTER 14Z FOR THE EAST COAST TAF SITES. FOR
KAPF TAF SITE...THE WEATHER WILL ALSO REMAIN DRY THROUGH MOST OF
THIS LABOR DAY. HOWEVER...A LATE WEST COAST SEA BREEZE COULD
DEVELOP AND PUSH INTO THE KAPF TAF SITE AFTER 21Z TODAY. SO WILL
PUT IN VCTS BETWEEN 21Z AND 00Z TODAY.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS AT ALL
OF THE TAF SITES FOR THIS LABOR DAY.
MARINE...EAST SOUTHEAST WINDS LESS THAN 15 KT WILL PREVAIL AS
THE ATLANTIC RIDGE REMAINS NORTH OF THE LOCAL WATERS. SEAS WILL BE
CORRESPONDINGLY LOW. A TROUGH WILL MOVE ACROSS THE WATERS LATE
WED- THU, BRINGING AN INCREASING CHANCE OF THUNDERSTORMS
ESPECIALLY ACROSS THE ATLANTIC WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 90 79 90 77 / 30 20 40 20
FORT LAUDERDALE 91 80 90 80 / 30 20 50 20
MIAMI 90 80 89 78 / 30 20 50 20
NAPLES 91 76 91 76 / 60 30 60 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
SHORT TERM...30/KOB
LONG TERM....60/BD
AREA FORECAST DISCUSSION
NWS MIAMI FL
728 AM EDT MON SEP 1 2014
.AVIATION...
MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST WITH A
MODERATE EAST WIND FLOW. ANTICIPATED TSRA DEVELOPMENT WILL BE OVER
THE INTERIOR WITH A WESTWARD PROPAGATION. AT THIS TIME, PLACED A
VCTS IN THE KAPF TAF AFT 19Z AND THEY COULD HAVE A BRIEF MVFR OR
EVEN IFR CIG/VSBY THROUGH THE AFTERNOON. EAST FLOW WILL PREVENT A
SEA BREEZE ALONG THE SOUTHWEST COAST BUT WIND IS LIKELY TO VEER TO
THE SSE AS IT TRIES TO FORM.
KOB
&&
.PREV DISCUSSION... /ISSUED 329 AM EDT MON SEP 1 2014/
HIGHLIGHTS...
* MODERATE RISK OF RIP CURRENTS ATLANTIC BEACHES
* SLIGHT TSTORM CHANCE EAST COAST, BETTER CHANCE GULF COAST TODAY
* STORMIER PATTERN MID-LATE WEEK; STRONG STORMS POSSIBLE
DISCUSSION...
THE WEATHER PATTERN ON THIS LABOR DAY WILL REMAIN
MOSTLY UNCHANGED FROM YESTERDAY. RIDGE AXIS WILL REMAIN OVER NORTH
FLORIDA, MAINTAINING AN EASTERLY WIND FLOW LOCALLY WITH CONVECTIVE
FOCUS ALONG THE GULF COAST IN THE AFTERNOON. LOW LEVEL WINDS WILL
BE STRONG ENOUGH TO DISALLOW A FULL GULF SEA BREEZE FROM
DEVELOPING, BUT SOME VEERING OF THE WIND FIELD IS EXPECTEDTHERE
WHICH AGAIN WILL LEAD TO ENOUGH CONVERGENCE TO SPARK SOME TSTORM
DEVELOPMENT. ACROSS THE EAST COAST, HRRR SHOWS A SCENARIO SIMILAR
TO YESTERDAY WITH QUICK PASSING SHOWERS DEVELOPING. CANNOT RULE
OUT TSTORMS EAST COAST BUT CONVERGENCE WILL BE LACKING SO COVERAGE
WOULD BE ISOLATED AT BEST.
LIKE YESTERDAY, A LIMITING FACTOR FOR MORE ACTIVE TSTORMS IS THE
LACK OF A FULL FLEDGED ONSHORE GULF SEA BREEZE. HOWEVER, CANNOT
RULE OUT A STRONG TSTORM OR TWO GIVEN SOME CONVERGENCE ALONG WITH
THE INSTABILITY AND CONTINUED DRY AIR ALOFT. WIND GUSTS OF 40-50
MPH IS THE PRIMARY THREAT.
A DEEP LAYERED TROUGH EAST OF THE BAHAMAS IS SHOWN BY THE GLOBAL
MODELS TO MOVE WEST AND ACROSS SOUTH FLORIDA WED NIGHT-THU. THIS
WILL BE ASSOCIATED WITH COOLING ALOFT ALONG WITH INCREASING
MOISTURE, SPELLING A STORMIER PERIOD MID WEEK AND EVEN INTO LATE
WEEK AS HIGHER INSTABILITY REMAINS. POPS ACCORDINGLY SHOW AN
UPWARD TREND MID-LATE WEEK. COULD SEE SOME STRONG STORMS ANYWHERE
BEGINNING WED THROUGH LATE WEEK DUE TO THE COLD AIR ALOFT AND
TROUGH PASSAGE, THOUGH MORE CLOUDINESS WOULD BE A LIMITING FACTOR.
/GREGORIA
AVIATION...
HIGH PRESSURE WILL SLOWLY WEAKEN OVER THE SOUTHEASTERN UNITED
STATES TODAY WHICH IN TURN WILL KEEP A EASTERLY WIND FLOW OF
AROUND 5 KNOTS THROUGH EARLY THIS MORNING AT ALL OF THE TAF SITES.
THE WIND DIRECTION WILL REMAIN EASTERLY AFTER 14Z TODAY BUT
INCREASE TO AROUND 10 KNOTS OVER ALL OF THE TAF SITES.
THE WEATHER SHOULD REMAIN DRY THROUGH THE EARLY MORNING HOURS BEFORE
SOME SHOWERS WORKS INTO THE EAST COAST TAF SITES AFTER 14Z.
SO WILL PUT IN VCSH AFTER 14Z FOR THE EAST COAST TAF SITES. FOR
KAPF TAF SITE...THE WEATHER WILL ALSO REMAIN DRY THROUGH MOST OF
THIS LABOR DAY. HOWEVER...A LATE WEST COAST SEA BREEZE COULD
DEVELOP AND PUSH INTO THE KAPF TAF SITE AFTER 21Z TODAY. SO WILL
PUT IN VCTS BETWEEN 21Z AND 00Z TODAY.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS AT ALL
OF THE TAF SITES FOR THIS LABOR DAY.
MARINE...EAST SOUTHEAST WINDS LESS THAN 15 KT WILL PREVAIL AS
THE ATLANTIC RIDGE REMAINS NORTH OF THE LOCAL WATERS. SEAS WILL BE
CORRESPONDINGLY LOW. A TROUGH WILL MOVE ACROSS THE WATERS LATE
WED- THU, BRINGING AN INCREASING CHANCE OF THUNDERSTORMS
ESPECIALLY ACROSS THE ATLANTIC WATERS.
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS COLUMBIA SC
1106 AM EDT MON SEP 1 2014
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL EXTEND INTO THE FORECAST AREA FROM THE
ATLANTIC THROUGH THE MIDDLE OF THE WEEK. A PERSISTENT UPPER RIDGE
WILL HELP MAINTAIN THE HOT TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NOT MUCH HAS CHANGED IN THE ATMOSPHERE OVER THE PAST 24 HOURS
REGARDING THE OVERALL WEATHER PATTERN OVER THE REGION. SURFACE
HIGH PRESSURE CENTERED OVER THE WESTERN ATLANTIC WILL CONTINUE TO
RIDGE INTO THE FORECAST AREA TODAY WITH GENERALLY MOIST SOUTHERLY
FLOW. IN THE UPPER LEVELS...THE RIDGE AXIS HAS SHIFTED SLIGHTLY TO
THE EAST TOWARDS THE COAST IN RESPONSE TO SHORTWAVE ENERGY PUSHING
INTO THE OHIO/TENNESSEE VALLEYS. MORNING MESOANALYSIS SHOWS A
PRECIPITABLE WATER GRADIENT ACROSS THE REGION FROM 1.5 INCHES IN
THE WESTERN MIDLANDS TO 1.8 INCHES IN THE EASTER MIDLANDS WITH A
POCKET OF DRY AIR AROUND 850MB IN THE UPSTATE INTO THE WESTERN
MIDLANDS.
DESPITE THE UPPER RIDGING OVER THE REGION...THE NAM SHOWS A
SHORTWAVE TROUGH MOVING INTO THE RIDGE OVER THE FORECAST AREA
LATE THIS AFTERNOON AND EVENING. THE COMBINATION OF STRONG
HEATING...WEAK CONVERGENCE INTO THE LEE-SIDE TROUGH...AND ABUNDANT
LOW LEVEL MOISTURE IN PLACE SHOULD SUPPORT LATE DAY THUNDERSTORM
DEVELOPMENT...ALTHOUGH UNCERTAINTY REMAINS ABOUT THE OVERALL
COVERAGE. THE SPC WRF SHOWS SCATTERED COVERAGE IN THE AFTERNOON
BECOMING WIDESPREAD DURING THE EVENING...WHILE THE LATEST HRRR AND
LOCAL OFFICE HI-RES WRF ARE VERY LIMITED WITH ANY CONVECTION.
WILL FAVOR HIGHEST POPS...CHANCE 30-40 PERCENT...IN THE
SOUTHEASTERN MIDLANDS AND CSRA WITH SLIGHT CHANCE POPS ELSEWHERE
LATE AFTERNOON INTO THE EVENING. SLOW STORM MOTION AND
RECOVERING PRECIPITABLE WATER VALUES NEAR 2 INCHES WILL SUPPORT
LOCALLY HEAVY RAIN. CANNOT RULE OUT AN ISOLATED SEVERE STORM OR
TWO OR LOCALIZED FLOODING DUE TO MODERATE INSTABILITIES.
TEMPERATURES ARE QUICKLY RISING AGAIN THROUGH THE UPPER 80S AT
THIS TIME AND WILL REACH THE MID TO UPPER 90S AGAIN TODAY. WENT
ABOVE MOS GUIDANCE WHICH HAS SHOWN A COOL BIAS FOR SEVERAL DAYS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
SURFACE RIDGING SHOULD CONTINUE EAST AND SOUTH OF THE FORECAST
AREA. EXPECT WEAK LEE-SIDE TROUGHING IN THE AREA. STRONG HEATING
AND CONVERGENCE INTO THIS FEATURE SHOULD HELP SUPPORT
THUNDERSTORMS...BUT CONTINUED UPPER RIDGING SHOULD LIMIT COVERAGE.
ALSO...THE SURFACE FEATURE SHOULD REMAIN WEAK. THE NAM AND GFS
MOS HAVE LOW POPS WITH THE CONSENSUS AROUND 20 PERCENT. IT WILL
REMAIN HOT. USED THE WARMER TEMPERATURE GUIDANCE BASED ON RECENT
VERIFICATION.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A WEAKENING FRONT STALLING BEFORE REACHING
THE AREA DURING THE MIDDLE OF THE WEEK. THE MODELS SHOW ANOTHER
FRONT MAY REACH THE AREA LATE IN THE MEDIUM-RANGE PERIOD. THE
MODELS INDICATE UPPER-LEVEL RIDGING CONTINUING. THE
GFS...ECMWF...AND EKD MOS SHOW ABOVE NORMAL TEMPERATURES WITH POPS
20 TO 30 PERCENT THROUGH THE PERIOD.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
SOME LINGERING CONVECTIVE DEBRIS CLOUDS AROUND THE AREA BUT VFR
CONDITIONS ARE EXPECTED THROUGH MUCH OF THE FORECAST PERIOD
OUTSIDE OF SCATTERED SHOWERS AND THUNDERSTORMS WHICH MAY IMPOSE
BRIEF MVFR/IFR CONDITIONS. THE CONFIDENCE IN ANY STORMS IMPACTING
ANY TERMINAL IS LOW AND THEREFORE NOT FORECAST AT THIS TIME BUT
SCATTERED CONVECTION IS EXPECTED AFTER 20Z. LIGHT AND VARIABLE
WINDS WILL BECOME MORE SOUTHERLY BY AFTERNOON BEFORE GOING LIGHT
AND VARIABLE TO CALM AGAIN OVERNIGHT.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN LATE NIGHT
AND EARLY MORNING STRATUS AND FOG. SCATTERED MAINLY AFTERNOON
SHOWERS AND THUNDERSTORMS TUESDAY THROUGH FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
NEAR TERM...HC
AVIATION...HC
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1001 AM CDT Mon Sep 1 2014
.UPDATE...
ISSUED AT 1001 AM CDT MON SEP 1 2014
Line of strong to severe thunderstorms tracked across Iowa last
night, then rapidly dissipated as it pushed toward the
Mississippi River early this morning. Outflow boundary from this
dying convection is currently approaching the I-55 corridor
as evidenced by westerly winds across all sites in the Illinois
River Valley. Think this outflow will eventually serve as the
primary focus for additional thunderstorm development later today.
Still some question as to exactly where the boundary will lay out
and when convection will fire, but the latest thinking from SPC
has pushed the best severe weather risk much further southeast,
generally along/south of a Danville to Jacksonville line. HRRR is
performing very poorly this morning and its solution has been
completely disregarded. Meanwhile, the 12z NAM seems to have at
least a reasonable handle on the situation, showing storms
developing by early afternoon near I-55, then shifting further
east and south later in the day. Will continue to monitor
stability parameters to see if projected 1500 to 2500J/kg CAPEs
can be realized. If the airmass destabilizes as predicted,
increasing shear values will help storms organize and potentially
produce large hail and damaging winds this afternoon into this
evening. Am still concerned about the threat for heavy rainfall
across the E/SE CWA tonight as favorable jet dynamics produce
enhanced synoptic lift along/ahead of approaching cold front. As
storms become parallel to upper flow, training appears likely
tonight along/south of a Danville to Jacksonville line. Latest NAM
continues to put down some hefty rainfall totals across this area.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 355 AM CDT MON SEP 1 2014
Shortwave trough axis approaching Illinois from the west this
morning bringing a line of thunderstorms to the region. Trends this
morning are for the line splitting into to intense lines...one
grazing Knox, Peoria, Stark county and likely Marshall and Woodford
as it continues this morning. Have reports of pea-sized hail and
wind gusts 30-40 mph with the more intense storm cells. The intense
activity looks like it will have a break through central IL in the
early morning once this initial activity shifts east-northeastward.
Isolated thunderstorms will likely develop throughout the CWA during
the morning...however daytime heating will likely be necessary to
bring CAPE values up to 1500-2500 J/KG range to bring a better
chance for severe storms when combined with 30-50 kt bulk shear
values also shifting into central Illinois. Large hail and severe
wind gusts will be a threat with the stronger storms this
afternoon...and have continued mention of severe hail and heavy rain
in forecast grids beginning at 3 pm this afternoon...continuing
through around midnight. Heavy rain will continue through the night
as a potent and moist low-level jet continues to push through the
CWA...along with lift associated with the progressive trough and
cold frontal boundary.
&&
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 355 AM CDT MON SEP 1 2014
00Z models have trended slower with frontal boundary pushing into
southeast IL Tue especially the NAM model and have increase pops to
likely se of I-70 Tue morning. NAM model may be overdoing qpf
amounts Tue morning over southeast IL but models have trended higher
with qpf amounts with precipitable water values of 1.5-2 inches
from 12-15Z Tue and have increased qpf amounts to around a quarter
inch in southeast IL. IL river valley should be dry Tue and chances
of showers and thunderstorms will diminish from nw to se during
Tue afternoon. Highs 82-88F Tue and still rather humid especially
in southeast IL with dewpoints 70-75F while dewpoints lower into
mid 60s over IL river valley. Dry conditions return across area
Tue night with frontal boundary dropping south of area. Lows in
the low to mid 60s Tue night.
Models show frontal boundary starting to lift back north especially
over MS river valley and MO on Wed and have kept 20-30% chance of
showers and thunderstorms sw areas by Wed afternoon with ne areas
staying dry Wed. Warm highs in the mid to upper 80s Wed and model
guidance has trended upward in high temps Wed. Dewpoints elevate
during day Wed into upper 60s and lower 70s Wed afternoon.
Convection chances appear highest over northern IL Wed night closer
to short waves tracking into WI/northern IL and eventually eastward
into lower MI and northern IN. Have areas south of I-72 dry Wed
night.
Thu and Fri still appear to be back into the heat and humidity with
highs in the upper 80s and lower 90s and dewpoints peaking in the
low to mid 70s giving afternoon heat indices of upper 90s to lower 100s
especially Thu afternoon and in southeast IL Friday afternoon. A 593
dm 500 mb high pressure ridge over the southeast states builds the
heat into central/southeast IL late this work week. Most of our area
should be dry Thu and Thu night with just slight chance of
convection Thu afternoon mainly over the Wabash river valley and
nw of IL river Thu night. Models have trended faster with cold
front dropping se through central IL Friday and thru southeast IL
Fri evening. Have increased pops Friday and also trending cooler
with temps and dewpoints during the weekend as 1025 mb high
pressure settles into the Great Lakes region.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 708 AM CDT MON SEP 1 2014
A mix of IFR and MVFR ceilings and southerly winds generally 8-12
kts this morning across central Illinois as a cold front
approaches from the west. A line of thunderstorm activity ahead of
the front continues to approach, however activity is generally weak
along portions of the line headed for central IL. As surface
heating takes place, thunderstorm development will intensify
through the early afternoon as daytime heating initiates and the
most intense portions of the storm system move into the region.
Some storms may become severe with hail and severe wind gusts this
afternoon and evening. Thunderstorm activity will shift toward
southeast portions of the state tonight. As no clear features
exist at this point to pinpoint timing of thunderstorms, have
broad-brushed thunderstorm activity with predominant -SHRA and VCTS
in TAFs starting 16Z- 17Z...then diminished VCTS/VCSH mention from
northwest to southeast overnight. Doubtful MVFR ceilings will
dissipate significantly through the day so have kept cigs no
better than bkn020-025 for the next 24 hours.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1153 AM EDT Mon Sep 1 2014
...Forecast Update...
Issued at 1153 AM EDT Mon Sep 1 2014
A small cluster of showers with some embedded thunder is progressing
quickly across central Kentucky and will be capable of producing
some locally gusty winds into the 40-50 mph range as it moves into
the Green River Lake region and an area of maximized DCAPE and
surface instability. Have updated the forecast grids to reflect
this area of precipitation, along with the few other showers that
are scattered around the area.
Issued at 859 AM EDT Mon Sep 1 2014
Widely scattered showers have formed in a corridor of higher surface
dew points and CAPE, and diminished CIN, from Memphis to Detroit.
have upped PoPs for a few hours this morning in the northwest LMK
CWA to account for this.
.SHORT TERM (Now through Tuesday)...
Issued at 310 AM EDT Mon Sep 1 2014
A slow-moving cool front to our northwest will bring a noticeable
increase in southwesterly winds today, with gusts of 15 to 25 mph
likely this afternoon. First off though we may see some isolated
low-topped showers this morning, with convergence along a weak
low-level jet early this morning already initiating some in central
IN. HRRR indicates better coverage than what I`ll have in my
forecast, as current guidance coverage already is too high.
Cloud cover from the moist low levels and as additional moisture
streams into the region today in a deep southwesterly flow should
keep high temperatures from getting too far above normal, with
readings likely topping out in the mid to upper 80s. The focus for
storms this evening will be to our west and northwest, closer to the
approaching front. These storms may be able to get into our southern
Indiana counties around or after midnight.
There still are some uncertainties about how convective development
will occur from early to late Tuesday, as a lot will depend on the
evolution of these storms moving into our region. Should those
storms get in here more toward daybreak, then convective debris
could be enough to prevent furthern development during the day
Tuesday, despite relatively high precipitable waters. Should those
storms die off overnight and leave boundaries behind, Tuesday could
become more active with heating. Will leave in likely pops for the
day Tuesday, as would lean more towards the latter solution that
we`ll see a few breaks in the clouds to generate more storms.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Sep 01 2014
Tuesday Night and Wednesday...
Surface high pressure will slide over the Ohio Valley behind the
nearly washed out front to our south on Tuesday night. An isolated
shower or storm could linger into the evening hours across the south
or east CWA, otherwise expect a dry and slightly cooler night. Lows
should drop into the upper 60s and around 70. Isolated or widely
scattered diurnally driven showers/storms are expected to be
possible across southern KY on Wednesday. Most areas will stay dry
with mostly sunny skies and highs in the 85 to 88 degree range.
Wednesday Night - Friday...
The southern CONUS upper ridge will build over the area to end the
week, however this will not be enough to suppress diurnally
driven convection each afternoon and early evening. Will continue
mention of isolated to widely scattered coverage on Thursday, with
better coverage on Friday more solidly in the scattered range. Along
with this ridge, the heat and humidity will return with highs in the
upper 80s to around 90 each day. With dew points in the low 70s each
day, conditions will feel quite muggy. The environment should become
pretty unstable each afternoon/evening, however the lack of deep
layer flow will keep any convection pulse in nature. Lows by
Thursday night will be back in the low 70s.
Friday Night - Saturday Night...
The upper ridge will be suppressed southward to start the weekend, as
a wave skirts along the eastern US/Canada border. This will drag a
stronger cold front toward our moist and unstable airmass, keeping
scattered storms in play on Friday night. Saturday should bring the
best chance of storms for the whole forecast period as the front
tries to slide through. Have gone with 40-50% coverage. With
slightly better deep layer flow over the area, the threat for a few
stronger storms seems reasonable. Biggest concern would be gusty
winds, along with cloud to ground lightning and brief heavy
rainfall. A few storms could linger in our south and east Saturday
evening.
Expect more mild lows on Friday night with the mercury only dropping
to the low 70s. Highs on Saturday will be dependent on convection
and where the frontal boundary resides, but it looks like temps will
max out around 80 north, to the mid or upper 80s south. Lows
Saturday night will be cooler on the north side of the boundary.
Look for readings in the 60s.
Sunday...
Surface high pressure takes back over on Sunday, bringing dry and
cooler conditions to start the new work week. Look for highs in the
upper 70s and low 80s, with lows Sunday night expected to be in the
upper 50s and low 60s!
&&
.AVIATION (12Z TAF Update)...
Issued at 640 AM EDT Mon Sep 1 2014
Have a few light rain showers forming north of a KSDF/KLEX line this
hour, but even should the rain make the terminals it should be light
enough not to reduce visibility much. The bigger factor now is
ceilings, with them hovering between MVFR and IFR at those two
sites, and KBWG may see it soon too. These clouds will lift by mid
morning. An isolated storm still cannot be ruled out later this
afternoon, but again coverage too limited to put in TAFs at this
time. Should see more storms coming in early Tuesday, first at KSDF
as a cool front approaches the region.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........13
Short Term.....RJS
Long Term......BJS
Aviation.......RJS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1048 AM EDT MON SEP 1 2014
.UPDATE...
ISSUED AT 1048 AM EDT MON SEP 1 2014
UPDATED THE FORECAST TO INCLUDE ALL OF EASTERN KENTUCKY IN THE CHANCE
OF PRECIPITATION TODAY BASED ON THE HIGH HRRR AND RUC MODEL OUTPUT AS
WELL AS THE CURRENT RADAR. BASED ON THE NAM BUFFER SOUNDINGS...DO
HAVE SOME CONCERN THAT SOME OF THE STORMS TODAY COULD PRODUCE
STRONG...BUT SUB SEVERE...WIND GUSTS TODAY. THERE IS SUFFICIENT
INSTABILITY AND SOME DRY AIR ALOFT THAT WOULD MAKE THIS FAVORABLE.
STILL HAVE CONCERN FOR SOME STRONG STORMS FOR TUESDAY AFTERNOON AND
EVENING AS WELL. WOULD NOT BE TOO SURPRISED TO SEE EASTERN KENTUCKY IN
AN SPC SLIGHT RISK BOX FOR TOMORROW. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 647 AM EDT MON SEP 1 2014
CLOUD COVER HAS EXPANDED A BIT FROM EARLIER...SO HAVE ADJUSTED THE
SKY COVER TO REFLECT CLOUDIER SKIES THROUGH DAYBREAK. ALSO ADJUSTED
TEMPERATURES UP A FEW DEGREES ACROSS THE BOARD AS THE CLOUDS ARE
HOLDING TEMPERATURES UP MAINLY IN THE LOW 70S. HRRR CONTINUES TO
PAINT OUT SOME ISOLATED TO SCATTERED SHOWERS AND STORMS THIS
AFTERNOON...AND THE 06Z NAM HAS ALSO NOW SUPPORTING A FEW SHOWERS AND
STORMS. THUS IT DOES LOOK LIKE SOME ACTIVITY CAN BE EXPECTED BY THE
AFTERNOON HOURS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 331 AM EDT MON SEP 1 2014
ZONAL FLOW RESIDES ACROSS KENTUCKY THIS MORNING...WITH A SHORTWAVE
TROUGH PUSHING ACROSS THE NORTHERN PLAINS. THE ZONAL FLOW FOR TODAY
WILL MEAN A QUIETER DAY. HOWEVER...A SUBTLE UPPER LEVEL WAVE WILL
PUSH ACROSS CENTRAL/NORTHEAST KENTUCKY THIS AFTERNOON AND EVENING.
WHILE OPERATIONAL GUIDANCE SUGGESTS VERY LITTLE IF ANY PRECIPITATION
TODAY...HI RES MODELS HAVE BEEN CONSISTENT ON SHOWING ISOLATED TO
SCATTERED CONVECTION DEVELOPING TODAY. THE MODEL GUIDANCE DOESN`T
SEEM TO MATCH UP TO WHAT THE HI RES MODELS ARE SHOWING. GIVEN THE
RECENT HISTORY OF HI RES MODELS DOING FAIRLY WELL WITH
CONVECTION...HAVE OPTED TO GO WITH ISOLATED TO SCATTERED SHOWERS AND
STORMS THIS AFTERNOON WITH THE HIGHEST CORRIDOR OF POPS FROM SOUTH
CENTRAL KENTUCKY...INTO NORTHERN AND NORTHEAST KENTUCKY.
HOWEVER...CANNOT RULE OUT A FEW ISOLATED SHOWERS OR STORMS DEVELOPING
ON THE HIGHER TERRAIN TO THE SOUTHEAST. WITH MODEST PRECIPITABLE
WATER VALUES AROUND 1.7 AND VERY HIGH FREEZING LEVELS (>15KFT)
POTENTIAL MAY EXISTS FOR SOME PERIODS OF VERY HEAVY RAIN.
FORTUNATELY...STORM MOVEMENT SHOULD BE SUFFICIENT TO LIMIT ANY
FLOODING CONCERNS TODAY.
THE SHOWERS/STORMS TODAY WILL BE TIED TO THE PEAK INSTABILITY HOURS
FROM MID AFTERNOON TO EARLY EVENING...BEFORE DYING OFF. THIS WILL
YIELD A QUITE NIGHT ACROSS THE AREA TODAY. CLEARING SKIES COULD YIELD
SOME PATCHY FOG...BUT WE MAY KEEP ENOUGH WIND AGAIN TO LIMIT IT TO
SOME DEGREE. THE SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL SEND
A WEAK COLD FRONT INTO THE OHIO RIVER VALLEY REGION. THIS WILL SPARK
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP ON
TUESDAY. THESE WILL TRACK SOUTHEAST ACROSS EASTERN KENTUCKY THROUGH
THE AFTERNOON AND EVENING HOURS. WITH MODEST 30-40KT BULK SHEAR
VALUES...THE POTENTIAL WILL EXISTS FOR SOME LINEAR STORM SEGMENTS
CAPABLE OF DAMAGING WINDS. PLAN TO CONTINUE TO HIGHLIGHT THIS
POTENTIAL IN THE HWO. THE FRONT WILL WASH OUT AND STALL OVER SOUTHERN
KENTUCKY BY THE EVENING HOURS WITH ACTIVITY DYING OUT WITH THE LOSS
OF DAYTIME HEATING.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 410 AM EDT MON SEP 1 2014
WARM WEATHER IS EXPECTED TO CONTINUE INTO THE EXTENDED PERIOD. THE
EXTENDED PERIOD OF THE FORECAST WILL BEGIN WITH THE TROUGH IN THE
NEAR TERM DEPARTING TO THE NORTH AND EAST...WITH A RATHER ZONAL
PATTERN TO START OVERALL. THE NEAR TERM COLD FRONT IS EXPECTED TO
BE DROPPING OR HAVE DROPPED ACROSS THE REGION AT THE START OF THE
PERIOD...FROM TUE NIGHT INTO EARLY ON WEDNESDAY AND BRING ISOLATED TO
SCATTERED CONVECTION. THE BOUNDARY SHOULD BECOME MORE ILL DEFINED AND
RATHER WASHED OUT ON WEDNESDAY AS IT REACHES THE TN VALLEY REGION.
WITH THE BOUNDARY IN THE AREA...CONVECTION WILL REMAIN POSSIBLE
MAINLY ACROSS THE SOUTH AND SOUTHEAST ON WEDNESDAY. MID AND UPPER
LEVEL RIDGING IS THEN EXPECTED TO BRIEFLY AMPLIFY ACROSS THE
SOUTHEASTERN AND MID ATLANTIC STATES THROUGH FRIDAY.
AS THE RIDGE BUILDS AND A SHORTWAVE TROUGH OR TWO IN THE ZONAL FLOW
MOVES FROM THE CENTRAL PLAINS TOWARD THE LOWER OH VALLEY REGION AND
INTO THE MIDDLE OH VALLEY REGION...WHAT IS LEFT OF THE BOUNDARY AND
DEEPER MOISTURE SHOULD ALSO BEGIN TO RETREAT BACK INTO THE REGION BY
WED NIGHT INTO THU. THIS SHOULD LEAD TO AN ADDITIONAL PERIOD WHERE
CONVECTION IS POSSIBLE. THE MODEL CONSENSUS IS FOR THE RIDGE TO
BUILD IN BEHIND THIS SHORTWAVE FOR THU NIGHT AND INTO EARLY ON FRI.
OVERALL...CONVECTION FROM THU NIGHT INTO FRIDAY MAY HAVE SOMEWHAT OF
A DIURNAL FLAVOR.
ALSO DURING THIS TIME...A SERIES OF TROUGHS WILL TRAVERSE THE
NORTHERN STREAM AND SEND A COLD FRONT SOUTH INTO AND GRADUALLY ACROSS
THE THE LOWER OH VALLEY REGION AND EASTERN KENTUCKY THIS WEEKEND.
THIS WILL BRING PERIOD OF UNSETTLED WEATHER...WITH PROLONGED CHANCES
FOR SHOWERS AND THUNDERSTORMS FROM SATURDAY INTO SUNDAY.
TEMPERATURES ARE EXPECTED TO AVERAGE NEAR TO A FEW DEGREES ABOVE
NORMAL FROM WED INTO SATURDAY FOR DAYTIME HIGHS...WITH OVERNIGHT LOW
HAVING THE GREATER DEPARTURE OF NEARLY 5 DEGREES ON AVERAGE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 647 AM EDT MON SEP 1 2014
LOW CLOUDS HAVE DEVELOPED AND SPREAD ACROSS MUCH OF EASTERN KENTUCKY
THIS MORNING. FOR THE MOST PART...MVFR CIGS ARE BEING REPORTED.
HOWEVER...A FEW SPOTS IN THE NORTH MAY BE DOWN TO IFR CIGS. WE SHOULD
SEE GRADUAL IMPROVEMENT THROUGH THE MORNING HOURS BEFORE VFR
CONDITIONS RETURN BY MIDDAY. ISOLATED TO SCATTERED SHOWERS AND STORMS
STILL LOOK LIKE A POSSIBILITY THIS AFTERNOON...BUT NO ENOUGH COVERAGE
OR CONFIDENCE TO INCLUDE IN THE TAFS. VFR CONDITIONS LOOK TO CONTINUE
THROUGH TONIGHT WITH ONLY SOME VERY PATCHY VALLEY FOG. AT THIS
TIME...THIS IS NOT EXPECTED TO IMPACT THE TAF SITES TONIGHT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...KAS
LONG TERM...JP
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
849 AM CDT Mon Sep 1 2014
.UPDATE...
Issued at 849 AM CDT MON SEP 1 2014
Clearly evident yesterday`s and even some of last night`s models
were unable to resolve and capture several ongoing elements. PoPs
have been modified to capture ongoing convection over the east
that wasn`t model depicted prior. Also, winds were up quicker than
forecast this morning. 12z upper air data shows 30-40kt low level
jet already established. Thus, that leads us to the fact we are
already at Lake Wind Advisory criteria. Given it`s the holiday,
will go ahead with one. Gusty southwest winds expected 10 to 20
mph with 25+ mph winds possible at times. Not necessarily the
optimum trajectory, but quite breezy none the less. Meanwhile,
kept chance of convection going more aggressively than previously
forecast, given the amount of heating we will see ahead of the
decaying activity to our west. The HRRR shows some development in
this region of less cloud cover over the next several hours,
before dying off later in the afternoon. Will see if this actually
comes to fruition. For now, will keep PoPs in the chance category.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 200 AM CDT MON SEP 1 2014
MCS dropping down across MO will spread its clouds into/across PAH
FA this morning. It will also lay out some boundaries, the primary
one of which lays out across our northern tier this afternoon,
where we`ll have a slgt/small chance mentionable Pop.
As the mean energy in the long wave moves across the MS and Wabash
river valleys tonight and Tuesday, it will drag this primary
boundary into the heart of the FA and result in an uptick in Pops
to likely cat or better, particularly during the day Tuesday. This
has been a consistent model signal and looks a good bet with fropa
thru much of the area by 00Z Wed.
The front/boundary hangs up across our southern tier or just to
the south Tue night, and returns as a warm sector boundary late
Tue night and Wed. This is indicated by several model members so we
adjusted Pops accordingly.
Temps look to remain summerlike at or just above climo norms from
the mid/upr 80s to near 90 for highs, and generally in the
u60s/lower 70s for lows, with continued muggy dew points.
.LONG TERM...(Wednesday Night through Sunday)
Issued at 302 AM CDT MON SEP 1 2014
The PAH forecast area will be under the stabilizing influence
(aloft) of a broad mid level ridge late in the week, though some
models indicate that, with the substantial diurnal lower trop
instability present each day, some deep moist convection may be
strong enough to get past the warm mid level cap in some locations
during the daytime.
Meanwhile, a nrn stream longwave trof will be in the process of
lowering mid level heights across most of the CONUS. A sfc cold
front is forecast to sink sewd into the OH river valley by sometime
early Sat, with some timing differences among the med range models.
This feature will provide additional focus for lifting of abundant
moist air, thus PoPs are now 40-50 percent during the day Sat behind
the front. By Sunday, a drier air mass should be making its way into
our region, cutting off pcpn. However, the GFS and its ensemble
means suggested the center of the high (over the upper Midwest) may
be farther east than the ECMWF and its ensemble means indicated, and
therefore some warm advection showers/tstms may erupt just to our
west. We will have to wait and see how long the drying effects of
the dome of high sfc pressure actually last.
Warm and humid conditions will prevail late in the week ahead of the
front, with heat indices peaking around 100 Thu and Fri, but
especially Fri. For this forecast package, the frontal passage
should provide us end-of-the-weekend dewpoints in the 60s along with
&&
.AVIATION...
Issued at 200 AM CDT MON SEP 1 2014
Will monitor tonight for any possible developing restrictions to
vsbys pre dawn. Cigs develop as MCS moves this way, restrictions
to MVFR possible at times, but believe will generally stay VFR.
Anticipate increasing gradient/winds during the day ahead of
approaching boundary. Pops enter forecast tonight but refrain from
terminal mention at this writing.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...LAKE WIND ADVISORY until 6 PM CDT this evening FOR ILZ075>078-
080>094.
MO...LAKE WIND ADVISORY until 6 PM CDT this evening FOR MOZ076-086-
087-100-107>112-114.
IN...LAKE WIND ADVISORY until 6 PM CDT this evening FOR INZ081-082-
085>088.
KY...LAKE WIND ADVISORY until 6 PM CDT this evening FOR KYZ001>022.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
859 AM EDT Mon Sep 1 2014
...Forecast Update...
Issued at 859 AM EDT Mon Sep 1 2014
Widely scattered showers have formed in a corridor of higher surface
dew points and CAPE, and diminished CIN, from Memphis to Detroit.
have upped PoPs for a few hours this morning in the northwest LMK
CWA to account for this.
.SHORT TERM (Now through Tuesday)...
Issued at 310 AM EDT Mon Sep 1 2014
A slow-moving cool front to our northwest will bring a noticeable
increase in southwesterly winds today, with gusts of 15 to 25 mph
likely this afternoon. First off though we may see some isolated
low-topped showers this morning, with convergence along a weak
low-level jet early this morning already initiating some in central
IN. HRRR indicates better coverage than what I`ll have in my
forecast, as current guidance coverage already is too high.
Cloud cover from the moist low levels and as additional moisture
streams into the region today in a deep southwesterly flow should
keep high temperatures from getting too far above normal, with
readings likely topping out in the mid to upper 80s. The focus for
storms this evening will be to our west and northwest, closer to the
approaching front. These storms may be able to get into our southern
Indiana counties around or after midnight.
There still are some uncertainties about how convective development
will occur from early to late Tuesday, as a lot will depend on the
evolution of these storms moving into our region. Should those
storms get in here more toward daybreak, then convective debris
could be enough to prevent furthern development during the day
Tuesday, despite relatively high precipitable waters. Should those
storms die off overnight and leave boundaries behind, Tuesday could
become more active with heating. Will leave in likely pops for the
day Tuesday, as would lean more towards the latter solution that
we`ll see a few breaks in the clouds to generate more storms.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Sep 01 2014
Tuesday Night and Wednesday...
Surface high pressure will slide over the Ohio Valley behind the
nearly washed out front to our south on Tuesday night. An isolated
shower or storm could linger into the evening hours across the south
or east CWA, otherwise expect a dry and slightly cooler night. Lows
should drop into the upper 60s and around 70. Isolated or widely
scattered diurnally driven showers/storms are expected to be
possible across southern KY on Wednesday. Most areas will stay dry
with mostly sunny skies and highs in the 85 to 88 degree range.
Wednesday Night - Friday...
The southern CONUS upper ridge will build over the area to end the
week, however this will not be enough to suppress diurnally
driven convection each afternoon and early evening. Will continue
mention of isolated to widely scattered coverage on Thursday, with
better coverage on Friday more solidly in the scattered range. Along
with this ridge, the heat and humidity will return with highs in the
upper 80s to around 90 each day. With dew points in the low 70s each
day, conditions will feel quite muggy. The environment should become
pretty unstable each afternoon/evening, however the lack of deep
layer flow will keep any convection pulse in nature. Lows by
Thursday night will be back in the low 70s.
Friday Night - Saturday Night...
The upper ridge will be suppressed southward to start the weekend, as
a wave skirts along the eastern US/Canada border. This will drag a
stronger cold front toward our moist and unstable airmass, keeping
scattered storms in play on Friday night. Saturday should bring the
best chance of storms for the whole forecast period as the front
tries to slide through. Have gone with 40-50% coverage. With
slightly better deep layer flow over the area, the threat for a few
stronger storms seems reasonable. Biggest concern would be gusty
winds, along with cloud to ground lightning and brief heavy
rainfall. A few storms could linger in our south and east Saturday
evening.
Expect more mild lows on Friday night with the mercury only dropping
to the low 70s. Highs on Saturday will be dependent on convection
and where the frontal boundary resides, but it looks like temps will
max out around 80 north, to the mid or upper 80s south. Lows
Saturday night will be cooler on the north side of the boundary.
Look for readings in the 60s.
Sunday...
Surface high pressure takes back over on Sunday, bringing dry and
cooler conditions to start the new work week. Look for highs in the
upper 70s and low 80s, with lows Sunday night expected to be in the
upper 50s and low 60s!
&&
.AVIATION (12Z TAF Update)...
Issued at 640 AM EDT Mon Sep 1 2014
Have a few light rain showers forming north of a KSDF/KLEX line this
hour, but even should the rain make the terminals it should be light
enough not to reduce visibility much. The bigger factor now is
ceilings, with them hovering between MVFR and IFR at those two
sites, and KBWG may see it soon too. These clouds will lift by mid
morning. An isolated storm still cannot be ruled out later this
afternoon, but again coverage too limited to put in TAFs at this
time. Should see more storms coming in early Tuesday, first at KSDF
as a cool front approaches the region.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........13
Short Term.....RJS
Long Term......BJS
Aviation.......RJS
AREA FORECAST DISCUSSION
NWS JACKSON KY
647 AM EDT MON SEP 1 2014
.UPDATE...
ISSUED AT 647 AM EDT MON SEP 1 2014
CLOUD COVER HAS EXPANDED A BIT FROM EARLIER...SO HAVE ADJUSTED THE
SKY COVER TO REFLECT CLOUDIER SKIES THROUGH DAYBREAK. ALSO ADJUSTED
TEMPERATURES UP A FEW DEGREES ACROSS THE BOARD AS THE CLOUDS ARE
HOLDING TEMPERATURES UP MAINLY IN THE LOW 70S. HRRR CONTINUES TO
PAINT OUT SOME ISOLATED TO SCATTERED SHOWERS AND STORMS THIS
AFTERNOON...AND THE 06Z NAM HAS ALSO NOW SUPPORTING A FEW SHOWERS AND
STORMS. THUS IT DOES LOOK LIKE SOME ACTIVITY CAN BE EXPECTED BY THE
AFTERNOON HOURS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 331 AM EDT MON SEP 1 2014
ZONAL FLOW RESIDES ACROSS KENTUCKY THIS MORNING...WITH A SHORTWAVE
TROUGH PUSHING ACROSS THE NORTHERN PLAINS. THE ZONAL FLOW FOR TODAY
WILL MEAN A QUIETER DAY. HOWEVER...A SUBTLE UPPER LEVEL WAVE WILL
PUSH ACROSS CENTRAL/NORTHEAST KENTUCKY THIS AFTERNOON AND EVENING.
WHILE OPERATIONAL GUIDANCE SUGGESTS VERY LITTLE IF ANY PRECIPITATION
TODAY...HI RES MODELS HAVE BEEN CONSISTENT ON SHOWING ISOLATED TO
SCATTERED CONVECTION DEVELOPING TODAY. THE MODEL GUIDANCE DOESN`T
SEEM TO MATCH UP TO WHAT THE HI RES MODELS ARE SHOWING. GIVEN THE
RECENT HISTORY OF HI RES MODELS DOING FAIRLY WELL WITH
CONVECTION...HAVE OPTED TO GO WITH ISOLATED TO SCATTERED SHOWERS AND
STORMS THIS AFTERNOON WITH THE HIGHEST CORRIDOR OF POPS FROM SOUTH
CENTRAL KENTUCKY...INTO NORTHERN AND NORTHEAST KENTUCKY.
HOWEVER...CANNOT RULE OUT A FEW ISOLATED SHOWERS OR STORMS DEVELOPING
ON THE HIGHER TERRAIN TO THE SOUTHEAST. WITH MODEST PW`S AROUND 1.7
AND VERY HIGH FREEZING LEVELS (>15KFT) POTENTIAL MAY EXISTS FOR SOME
PERIODS OF VERY HEAVY RAIN. FORTUNATELY...STORM MOVEMENT SHOULD BE
SUFFICIENT TO LIMIT ANY FLOODING CONCERNS TODAY.
THE SHOWERS/STORMS TODAY WILL BE TIED TO THE PEAK INSTABILITY HOURS
FROM MID AFTERNOON TO EARLY EVENING...BEFORE DYING OFF. THIS WILL
YIELD A QUITE NIGHT ACROSS THE AREA TODAY. CLEARING SKIES COULD YIELD
SOME PATCHY FOG...BUT WE MAY KEEP ENOUGH WIND AGAIN TO LIMIT IT TO
SOME DEGREE. THE SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL SEND
A WEAK COLD FRONT INTO THE OHIO RIVER VALLEY REGION. THIS WILL SPARK
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP ON
TUESDAY. THESE WILL TRACK SOUTHEAST ACROSS EASTERN KENTUCKY THROUGH
THE AFTERNOON AND EVENING HOURS. WITH MODEST 30-40KT BULK SHEAR
VALUES...THE POTENTIAL WILL EXISTS FOR SOME LINEAR STORM SEGMENTS
CAPABLE OF DAMAGING WINDS. PLAN TO CONTINUE TO HIGHLIGHT THIS
POTENTIAL IN THE HWO. THE FRONT WILL WASH OUT AND STALL OVER SOUTHERN
KENTUCKY BY THE EVENING HOURS WITH ACTIVITY DYING OUT WITH THE LOSS
OF DAYTIME HEATING.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 410 AM EDT MON SEP 1 2014
WARM WEATHER IS EXPECTED TO CONTINUE INTO THE EXTENDED PERIOD. THE
EXTENDED PERIOD OF THE FORECAST WILL BEGIN WITH THE TROUGH IN THE
NEAR TERM DEPARTING TO THE NORTH AND EAST...WITH A RATHER ZONAL
PATTERN TO START OVERALL. THE NEAR TERM COLD FRONT IS EXPECTED TO
BE DROPPING OR HAVE DROPPED ACROSS THE REGION AT THE START OF THE
PERIOD...FROM TUE NIGHT INTO EARLY ON WEDNESDAY AND BRING ISOLATED TO
SCATTERED CONVECTION. THE BOUNDARY SHOULD BECOME MORE ILL DEFINED AND
RATHER WASHED OUT ON WEDNESDAY AS IT REACHES THE TN VALLEY REGION.
WITH THE BOUNDARY IN THE AREA...CONVECTION WILL REMAIN POSSIBLE
MAINLY ACROSS THE SOUTH AND SOUTHEAST ON WEDNESDAY. MID AND UPPER
LEVEL RIDGING IS THEN EXPECTED TO BRIEFLY AMPLIFY ACROSS THE
SOUTHEASTERN AND MID ATLANTIC STATES THROUGH FRIDAY.
AS THE RIDGE BUILDS AND A SHORTWAVE TROUGH OR TWO IN THE ZONAL FLOW
MOVES FROM THE CENTRAL PLAINS TOWARD THE LOWER OH VALLEY REGION AND
INTO THE MIDDLE OH VALLEY REGION...WHAT IS LEFT OF THE BOUNDARY AND
DEEPER MOISTURE SHOULD ALSO BEGIN TO RETREAT BACK INTO THE REGION BY
WED NIGHT INTO THU. THIS SHOULD LEAD TO AN ADDITIONAL PERIOD WHERE
CONVECTION IS POSSIBLE. THE MODEL CONSENSUS IS FOR THE RIDGE TO
BUILD IN BEHIND THIS SHORTWAVE FOR THU NIGHT AND INTO EARLY ON FRI.
OVERALL...CONVECTION FROM THU NIGHT INTO FRIDAY MAY HAVE SOMEWHAT OF
A DIURNAL FLAVOR.
ALSO DURING THIS TIME...A SERIES OF TROUGHS WILL TRAVERSE THE
NORTHERN STREAM AND SEND A COLD FRONT SOUTH INTO AND GRADUALLY ACROSS
THE THE LOWER OH VALLEY REGION AND EASTERN KENTUCKY THIS WEEKEND.
THIS WILL BRING PERIOD OF UNSETTLED WEATHER...WITH PROLONGED CHANCES
FOR SHOWERS AND THUNDERSTORMS FROM SATURDAY INTO SUNDAY.
TEMPERATURES ARE EXPECTED TO AVERAGE NEAR TO A FEW DEGREES ABOVE
NORMAL FROM WED INTO SATURDAY FOR DAYTIME HIGHS...WITH OVERNIGHT LOW
HAVING THE GREATER DEPARTURE OF NEARLY 5 DEGREES ON AVERAGE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 647 AM EDT MON SEP 1 2014
LOW CLOUDS HAVE DEVELOPED AND SPREAD ACROSS MUCH OF EASTERN KENTUCKY
THIS MORNING. FOR THE MOST PART...MVFR CIGS ARE BEING REPORTED.
HOWEVER...A FEW SPOTS IN THE NORTH MAY BE DOWN TO IFR CIGS. WE SHOULD
SEE GRADUAL IMPROVEMENT THROUGH THE MORNING HOURS BEFORE VFR
CONDITIONS RETURN BY MIDDAY. ISOLATED TO SCATTERED SHOWERS AND STORMS
STILL LOOK LIKE A POSSIBILITY THIS AFTERNOON...BUT NO ENOUGH COVERAGE
OR CONFIDENCE TO INCLUDE IN THE TAFS. VFR CONDITIONS LOOK TO CONTINUE
THROUGH TONIGHT WITH ONLY SOME VERY PATCHY VALLEY FOG. AT THIS
TIME...THIS IS NOT EXPECTED TO IMPACT THE TAF SITES TONIGHT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...KAS
LONG TERM...JP
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
640 AM EDT Mon Sep 1 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Tuesday)...
Issued at 310 AM EDT Mon Sep 1 2014
A slow-moving cool front to our northwest will bring a noticeable
increase in southwesterly winds today, with gusts of 15 to 25 mph
likely this afternoon. First off though we may see some isolated
low-topped showers this morning, with convergence along a weak
low-level jet early this morning already initiating some in central
IN. HRRR indicates better coverage than what I`ll have in my
forecast, as current guidance coverage already is too high.
Cloud cover from the moist low levels and as additional moisture
streams into the region today in a deep southwesterly flow should
keep high temperatures from getting too far above normal, with
readings likely topping out in the mid to upper 80s. The focus for
storms this evening will be to our west and northwest, closer to the
approaching front. These storms may be able to get into our southern
Indiana counties around or after midnight.
There still are some uncertainties about how convective development
will occur from early to late Tuesday, as a lot will depend on the
evolution of these storms moving into our region. Should those
storms get in here more toward daybreak, then convective debris
could be enough to prevent furthern development during the day
Tuesday, despite relatively high precipitable waters. Should those
storms die off overnight and leave boundaries behind, Tuesday could
become more active with heating. Will leave in likely pops for the
day Tuesday, as would lean more towards the latter solution that
we`ll see a few breaks in the clouds to generate more storms.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Sep 01 2014
Tuesday Night and Wednesday...
Surface high pressure will slide over the Ohio Valley behind the
nearly washed out front to our south on Tuesday night. An isolated
shower or storm could linger into the evening hours across the south
or east CWA, otherwise expect a dry and slightly cooler night. Lows
should drop into the upper 60s and around 70. Isolated or widely
scattered diurnally driven showers/storms are expected to be
possible across southern KY on Wednesday. Most areas will stay dry
with mostly sunny skies and highs in the 85 to 88 degree range.
Wednesday Night - Friday...
The southern CONUS upper ridge will build over the area to end the
week, however this will not be enough to suppress diurnally
driven convection each afternoon and early evening. Will continue
mention of isolated to widely scattered coverage on Thursday, with
better coverage on Friday more solidly in the scattered range. Along
with this ridge, the heat and humidity will return with highs in the
upper 80s to around 90 each day. With dew points in the low 70s each
day, conditions will feel quite muggy. The environment should become
pretty unstable each afternoon/evening, however the lack of deep
layer flow will keep any convection pulse in nature. Lows by
Thursday night will be back in the low 70s.
Friday Night - Saturday Night...
The upper ridge will be suppressed southward to start the weekend, as
a wave skirts along the eastern US/Canada border. This will drag a
stronger cold front toward our moist and unstable airmass, keeping
scattered storms in play on Friday night. Saturday should bring the
best chance of storms for the whole forecast period as the front
tries to slide through. Have gone with 40-50% coverage. With
slightly better deep layer flow over the area, the threat for a few
stronger storms seems reasonable. Biggest concern would be gusty
winds, along with cloud to ground lightning and brief heavy
rainfall. A few storms could linger in our south and east Saturday
evening.
Expect more mild lows on Friday night with the mercury only dropping
to the low 70s. Highs on Saturday will be dependent on convection
and where the frontal boundary resides, but it looks like temps will
max out around 80 north, to the mid or upper 80s south. Lows
Saturday night will be cooler on the north side of the boundary.
Look for readings in the 60s.
Sunday...
Surface high pressure takes back over on Sunday, bringing dry and
cooler conditions to start the new work week. Look for highs in the
upper 70s and low 80s, with lows Sunday night expected to be in the
upper 50s and low 60s!
&&
.AVIATION (12Z TAF Update)...
Issued at 640 AM EDT Mon Sep 1 2014
Have a few light rain showers forming north of a KSDF/KLEX line this
hour, but even should the rain make the terminals it should be light
enough not to reduce visibility much. The bigger factor now is
ceilings, with them hovering between MVFR and IFR at those two
sites, and KBWG may see it soon too. These clouds will lift by mid
morning. An isolated storm still cannot be ruled out later this
afternoon, but again coverage too limited to put in TAFs at this
time. Should see more storms coming in early Tuesday, first at KSDF
as a cool front approaches the region.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Short Term........RJS
Long Term.........BJS
Aviation..........RJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1100 AM EDT MON SEP 1 2014
LATEST UPDATE...
SHORT TERM
.SYNOPSIS...
ISSUED AT 330 AM EDT MON SEP 1 2014
A COLD FRONT WILL MOVE INTO THE GREAT LAKES REGION FROM THE WEST
LATER TODAY AND INTO TONIGHT. SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO DEVELOP OVER SOUTHWEST LOWER MICHIGAN FROM THE LATE MORNING HOURS
PERSISTING INTO THE EVENING. SOME OF THE STORMS FROM THE MIDDAY
HOURS THROUGH THE EVENING MAY BE SEVERE WITH LARGE HAIL AND STRONG
WINDS. SHOWERS AND STORMS WILL GRADUALLY TAPER OFF TONIGHT
FROM NORTH TO SOUTH AS THE FRONT DROPS SOUTHWARD INTO INDIANA. DRY
WEATHER IS THEN EXPECTED FOR THE MOST PART FROM TUESDAY THROUGH
WEDNESDAY. CHANCES FOR SHOWERS AND STORMS INCREASE ONCE AGAIN
WEDNESDAY NIGHT THROUGH FRIDAY AS A LOW PRESSURE SYSTEM TRAVERSES
THE AREA. TEMPERATURES THIS WEEK WILL BE NEAR TO ABOVE NORMAL WITH
HIGHS IN THE UPPER 70S TO 80S ALL WEEK. A COOL DOWN IS EXPECTED NEXT
WEEKEND BEHIND A COLD FRONT THAT MOVES THROUGH ON FRIDAY.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 1100 AM EDT MON SEP 1 2014
ISOLATED SEVERE WEATHER THREAT CONTINUES THIS AFTERNOON (2PM - 8PM)
EAST OF U.S. 131 WITH DAMAGING WIND GUSTS THE MAIN THREAT. BRIEF
LOCALIZED FLOODING TYPICAL OF STRONG THUNDERSTORMS IS ALSO POSSIBLE.
APPROACHING WEAK FRONTAL BOUNDARY...SEPARATING DEWPOINTS IN THE LOW
70S FROM THOSE IN THE MID 60S...IS CURRENTLY ORIENTED NORTH-SOUTH
ACROSS EASTERN WISCONSIN AND ILLINOIS. THERE IS ALSO CONSIDERABLE
CLOUDINESS ALONG AND AHEAD OF FRONT WHICH IS TEMPERATURES AND
DESTABILIZATION OFTHE AIRMASS.
THE FRONT WILL SWEEP EASTWARD ACROSS THE CWA THIS AFTERNOON AND
EARLY EVENING PROVIDING LOW LEVEL LIFT AND POTENTIAL FOCUS FOR
DEVELOPMENT OF NEW STORMS. ALOFT HOWEVER...THE LEAD SHORTWAVE AND
NOSE OF UPPER JET WILL PUSH EASTWARD OVER THE REGION WITH BEST DEEP
LIFT NORTH MAINLY NORTH OF THE AREA.
INSTABILITY AND WIND FIELDS ARE FAVORABLE FOR SEVERE STORMS WITH
CAPE VALUES OF 500 - 1500 J/KG...0-6 KM BULK SHEAR VALUES NEAR 40
KTS...AND 0-1KM SHEAR VALUES AROUND 20 KTS. HOWEVER...LACK OF DEEP
LIFT WILL LIMIT COVERAGE OF STORMS AND OVERALL SEVERE THEAT
SIGNICANTLY. THIS SOLUTION IS REFLECTED IN MANY OF THE HIGHER
RESOLUTION CONVECTION ALLOWING MODELS INCLUDING LAST FEW NSSL WRF
AND HRRR RUNS.
OTHERWISE...THE SHORT TERM IS RELATIVELY QUIET. ANY STORMS THIS
EVENING SHOULD WORK SOUTH OF THE AREA OVERNIGHT. NOT OUT OF THE
REALM OF POSSIBILITIES FOR A FEW SHOWERS ON TUESDAY...BUT FELT THE
THREAT WAS SMALL ENOUGH TO GO DRY. TUESDAY NIGHT AND WEDNESDAY
SHOULD BE DRY WITH RIDGING IN PLACE AT THE SURFACE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON SEP 1 2014
THE MOST UNSETTLED WEATHER IN THE LONG TERM LOOKS TO OCCUR IN THE
FIRST COUPLE OF DAYS...FROM THE BEGINNING OF THE PERIOD WED NIGHT
INTO FRI NIGHT. THE LATEST TREND IS FOR A LITTLE MORE POSSIBLE PCPN
WED NIGHT INTO THU WITH THE PASSAGE OF THE WARM FRONT THROUGH THE
AREA. THIS LOOKS TO BE THE CASE DUE TO THE GRADIENT/LOW LEVEL JET
EXPECTED TO BE A LITTLE STRONGER WITH A STRONGER TROUGH MOVING IN.
HOW QUICKLY THE FRONT MOVES THROUGH WILL DICTATE HOW WARM WE GET ON
THU. IF THE FRONT MOVES QUICK ENOUGH...WE COULD HAVE A CHC TO WARM
TOWARD 90 WITH H850 TEMPS OF 20C ADVECTING IN. FOR NOW...WE HAVE
SETTLED WITH THE MID-UPPER 80S WITH THE UNCERTAINTY OF THE PCPN.
WE WILL SEE ANOTHER BATCH OF CONVECTION BE POSSIBLE THEN CENTERED
AROUND FRI AS THE COLD FRONT PUSHES THROUGH AND ENCOUNTERING THE
VERY WARM AND MOIST AIR MASS. WE COULD HAVE SOME ASSISTANCE VIA THE
RRQ OF AN UPPER JET TO OUR N/NE THAT WOULD SUPPLEMENT THE COLD
FRONTAL PASSAGE.
THE REMAINDER OF THE LONG TERM FROM SAT THROUGH SUN LOOKS TO BE
RATHER QUIET...YET COOL. WE WILL SEE A CANADIAN AIR MASS FILTER IN
BEHIND THE THU/FRI SYSTEM WITH A DECENT NNE LOW LEVEL FLOW USHERING
IT IN. THE UPPER FLOW WILL BE FROM THE NW AND A BIT OF A TROUGH WILL
BE OVER THE AREA. THE FAR ERN FLANK OF A SFC RIDGE WILL BE
BUILDING IN AS THE SYNOPTIC PATTERN OVER THE COUNTRY WILL FEATURE A
FAIRLY BROAD/EXPANSIVE UPPER RIDGE FROM THE ERN PACIFIC INTO THE
ROCKIES. THIS SHOULD KEEP THE AREA DRY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 749 AM EDT MON SEP 1 2014
COMPLICATED WEATHER SCENARIO IN PLACE THIS MORNING WITH STRATUS
MOVING NORTH THROUGH THE TAF SITES AND THE POTENTIAL FOR
THUNDERSTORMS LOOMING.
THE STRATUS AND FOG SHOULD GRADUALLY LIFT THROUGH THE COURSE OF
THE MORNING...BUT IT HAS BECOME FAIRLY EXTENSIVE ACROSS SOUTHERN
LOWER MICHIGAN. BY AFTERNOON...EXPECTING VFR CEILINGS AND VSBYS
OUTSIDE OF THUNDERSTORMS.
AS FOR THUNDERSTORMS...THEY ARE ALREADY DEVELOPING ACROSS
PORTIONS OF NORTHERN ILLINOIS AND NORTHERN INDIANA. THE TREND
SHOULD BE FOR SCATTERED SHOWERS AND THUNDERSTORMS TO MOVE THROUGH
THE TAF SITES FROM 14Z OR SO THROUGH 23Z. TOO DIFFICULT TO NAIL
DOWN PREVAILING TIMING AT THIS POINT GIVEN THE HIT OR MISS NATURE
TO TODAY/S STORMS...SO HAVE VCTS WORDING IN ALL THE TAFS THIS
AFTERNOON.
OVERNIGHT...EXPECTING THE SHOWERS AND STORMS TO END WITH MVFR
CEILINGS TRYING TO SETTLE BACK IN.
IT WILL BECOME WINDY TODAY OUT OF THE SOUTH-SOUTHWEST...ESPECIALLY
FROM 15Z-23Z. WINDS FROM 200-220 AT 15-25 KNOTS SHOULD BE COMMON.
&&
.MARINE...
ISSUED AT 1100 AM EDT MON SEP 1 2014
SCA/BEACH HAZARD WORKING WELL WITHWIND GUSTS NEAR 30 KTS AND WAVE
AROUND 4 FT OBSERVED NORTH OF HOLLAND TOWARDS LUDINGTON AT THIS
TIME. WINDS WILL CONTINUE NEXT SEVERAL HOURS WITH WAVES UP TO 5
FEET. WINDS / WAVES WILL SUBSIDE QUICKLY LATE THIS AFTERNOON WITH
PASSAGE OF FRONT AND SHIFT OF WINDS TO A MORE WESTERLY DIRECTION.
THE NEXT POSSIBLE SET OF HEADLINES THAT MAY BE NEEDED FOR THE
NEARSHORE WATERS LOOKS TO START IN THE WED NIGHT/THU TIME FRAME AS
THE FLOW STRENGTHENS WITH A SURGE OF WARMER AIR WITH THE NEXT
FRONTAL SYSTEM POISED TO MOVE IN.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT MON SEP 1 2014
LOCALLY HEAVY RAIN IS CERTAINLY POSSIBLE TODAY GIVEN PRECIPITABLE
WATER VALUES SURGING TOWARDS 2 INCHES THIS AFTERNOON. THE RAIN WILL
BE CONVECTIVE IN NATURE THOUGH...SO ANY HEAVY RAIN WILL OCCUR IN
SWATHS AS OPPOSED TO BEING WIDESPREAD. RIVER LEVELS ARE ALL WITHIN
BANK...AND FORECAST BASIN AVERAGE RAINFALL AMOUNTS ARE ON THE ORDER
OF 0.20 TO 0.50 INCHES. THESE AMOUNTS SHOULD BE ABLE TO BE ABSORBED
BY THE RIVER SYSTEMS WITHOUT MUCH ISSUE.
TODAY/S ISSUE THOUGH WILL BE MONITORING THE SWATHS OF HEAVIER RAIN
THAT SWEEP THROUGH WITH THE STORMS. THINKING THE MOTION WILL BE
QUICK ENOUGH (NORTHEAST AT 35-45 MPH)...TO PREVENT MUCH OF AN ISSUE
WITH FLASH FLOODING.
NEXT GOOD CHANCE FOR RAIN WILL COME LATER THIS WEEK WITH A WARM
FRONT WEDNESDAY NIGHT INTO THURSDAY MORNING AND AGAIN FRIDAY AHEAD
OF A COLD FRONT. TOTAL RAINFALL WITH THIS SYSTEM COULD BE ON THE
ORDER OF A HALF INCH TO AN INCH.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MIZ037-043-050-
056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
LMZ844>849.
&&
$$
SYNOPSIS...DUKE
SHORT TERM...COBB
LONG TERM...NJJ
AVIATION...DUKE
HYDROLOGY...DUKE
MARINE...COBB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
744 AM EDT MON SEP 1 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT MON SEP 1 2014
WV IMAGERY AND RUC INDICATED A BROAD MID/UPPER LEVEL TROUGH FROM THE
ROCKIES INTO THE NRN/CNTRL PLAINS. AT THE SFC...A COLD FRONT
EXTENDED FROM NEAR INL THROUGH CNTRL MN INTO NW IA. A WEAK SHRTWV
FROM NE MN INTO NW WI SUPPORTED AN AREA OF SHOWERS AND ISOLD TSRA
OVER ERN MN INTO NW WI AND LAKE SUPERIOR. A STRONGER SHRTWV WAS
LOCATED OVER SW MN INTO NW IA. WITH ONLY MODEST 500-1000 J/KG
MUCAPE...ONLY A FEW TSRA WERE NOTED OVER THE REGION. THE MORE ACTIVE
CONVECTION OVER ERN LAKE SUPERIOR WAS ASSOCIATED WITH AN AREA OF
STRONGER 850 THETA-E ADVECTION AT THE NOSE OF THE LLJ.
TODAY...AS THE NW IA SHRTWV LIFTS TOWARD THE AREA WITH MODERATE
700-300 MB QVECTOR CONV AND THE COLD FRONT APPROACHES THE
AREA...EXPECT SHRA/TSRA COVERAGE TO INCREASE THIS MORNING. EVEN WITH
0-1KM/0-6KM SHEAR AROUND 40 KNOTS...SINCE INSTABILITY WILL REMAIN
LIMITED...MAINLY JUST BRIEF HEAVY RAIN IS EXPECTED. OVERALL RAINFALL
AMOUNTS SHOULD BE LIMITED GIVEN THE QUICK MOVEMENT OF THE CONVECTIVE
CELLS AND LACK OF LARGE SCALE ORGANIZATION. THE PCPN WILL DIMINISH
FROM WEST TO EAST THIS AFTERNOON AS THE COLD FRONT MOVES THROUGH AND
QVECTOR DIV SPREADS INTO UPPER MI IN THE WAKE OF THE SHRTWV. CLOUD
COVER WILL KEEP HIGH TEMPS NEAR OR SLIGHTLY BELOW SEASONAL AVERAGES
IN THE UPPER 60S TO AROUND 70.
TONIGHT...ANY LINGERING PCPN OVER THE ERN CWA IN THE EVENING WILL
END EARLY. OTHERWISE...A DRIER AIRMASS MOVING INTO THE AREA WITH
DEWPOINTS DROPPING TOWARD THE LOWER 50S WILL ALLOW TEMPS TO ALSO
DROP INTO THE LOWER TO MID 50S AS SKIES PARTIALLY CLEAR. AN INCREASE
IN CLOUD COVER IS EXPECTED LATE OVER THE SW CWA AHEAD OF THE NEXT
WEAK SHRTWV.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 321 AM EDT MON SEP 1 2014
IN THE WAKE OF STRONGER SHORTWAVE AND SFC FRONT MOVING THROUGH
TODAY...ANOTHER SHORTWAVE CLIPS ACROSS THE AREA ON TUESDAY IN
INCREASINGLY ZONAL FLOW ALOFT. MOISTURE IS LIMITED WITH THE WAVE AS
SOUNDINGS ONLY SHOW MOISTURE H8-H7. PRETTY HIGH BASED SHRA AND WILL
ALSO MENTION ISOLD TSRA WITH MLCAPE 500-1000 J/KG PER ECMWF AND GFS.
WILL INCLUDE SLIGHT CHANCE POPS. A LULL FOR TUE NIGHT AS SFC RIDGE
MOVES FROM MIDDLE MISSISSIPPI RIVER VALLEY TO THE OHIO VALLEY. LGT
SW WINDS ON PERIFERY OF THE RIDGE WILL LIMIT COOLING. LOWEST PWAT
FAR EAST CWA WHERE MIN TEMPS MAY FALL TO AROUND 50 DEGREES. ON
WEDNESDAY...GFS AND GEM-NH INDICATE SOME SHOWERS COULD OCCUR IN THE
AFTN OVER MAINLY THE WEST HALF CWA. WEAK SHORTWAVE IS THERE BUT ONLY
APPEARS THAT BEST MOISTURE INFLOW IS OVER FAR WEST CWA. WARM AIR
ADVECTION BOOSTS H85 TEMPS TO AROUND +15C SO AS LONG AS SKIES STAY
AT LEAST PARTLY CLOUDY...MAX TEMPS WILL TOP OUT IN THE MID 70S TO
LOWER 80S.
LATER WEDNESDAY NIGHT INTO THURSDAY MORNING LARGER SCALE LIFT
AHEAD OF UPPER TROUGH INCREASES OVER NORTHERN PLAINS AND WESTERN
GREAT LAKES. LIKELY WILL BE SOME SHORTWAVES SLIDING OUT OF NORTHERN
PLAINS AS WELL...THOUGH RIGHT NOW SIGNAL OF ANY STRONGER SHORTWAVE
IS MINIMAL. THERE IS A MID LEVEL JET MAX SLIDING OVER THE AREA AND
H85-H5 Q-VECTOR CONVERGENCE WILL BE ON THE INCREASE. PRIMARY SFC
TROUGH WILL BE OVER MINNESOTA AND BASED ON SFC WINDS AND
DWPNTS...THERE WILL BE A WARM FRONT VCNTY OF SOUTHERN/CENTRAL
MINNESOTA INTO WESTERN WISCONSIN. BULGE OF WARMTH ALOFT RESULTS IN
AN ELEVATED MIXED LAYER WITH H7-H5 LAPSE RATES OVER 8C/KM MAKING IT
OVER UPR LAKES AHEAD OF THE SFC TROUGH. RESERVOIR OF ML MUCAPE OVER
2000J/KG WILL BE JUST SOUTHWEST OF UPR MICHIGAN WITH MID LEVEL FLOW
SW-NE. EDGE OF SFC BASED CAPE AND ORIENTATION OF H85-H3 THICKNESSES
INDICATE THAT STRONGER STORMS MAY BE MORE TO SOUTHWEST OF UPR
MICHIGAN LATER WEDNESDAY NIGHT INTO THURSDAY MORNING. TOUGH TO SAY
AT THIS POINT THOUGH. CONSENSUS CHANCE POPS WORK FOR NOW SINCE THERE
WILL BE LARGE SCALE WARM AIR ADVECTION AND H85-H7 MOISTURE TRANSPORT
AIMED INTO THE AREA. MORE SHRA/TSRA POSSIBLE AS SFC FRONT WORKS
ACROSS UPR MICHIGAN LATER ON THURSDAY. PLENTY OF INSTABILITY AS
TEMPS IN THE SOUTH-SOUTHWEST FLOW AHEAD OF FRONT SHOULD REACH TOWARD
80 DEGREES WITH EVEN A FEW HOURS OF PARTIAL CLEARING SINCE H85 TEMPS
ARE 18-20C. MOISTURE AVAILABILITY/MID LEVEL CAPPING ALONG THE FRONT
REMAINS A CONCERN FOR COVERAGE OF SFC BASED STORMS IN THE AFTN. MODELS
MAY BE PICKING UP ON THIS AS GFS/ECMWF SHOW A MIN IN QPF 18Z-24Z BUT
THEN INCREASE IT BY 06Z ON FRIDAY AS FRONT WILL MAINLY BE SOUTH AND
EAST OF CWA BY THAT TIME. NO NEED TO GET TOO FANCY WITH THE GRIDS
ATTM GIVEN ALL THE UNCERTAINTY. KEPT WITH THE CONSENSUS CHANCE POPS
ON THURSDAY WITH THIS DROPPING OFF TO LOWER CHANCES THURSDAY NIGHT
CLOSER TO THE DEPARTING FRONT.
REST OF THE FORECAST LOOKS DRY AND COOLER AS HIGH PRESSURE BUILDS IN
ON FRIDAY AND WILL HOLD ON THROUGH NEXT WEEKEND. MAX TEMPS IN THE
MID 60S TO LOWER 70S. CHILLY LOWS POSSIBLE INLAND BOTH FRIDAY NIGHT
AND SATURDAY NIGHT DUE TO THE DRY AIRMASS AND LGT WINDS BENEATH THE
HIGH PRESSURE. BIAS CORRECTED GUIDANCES SHOWED MINS IN THE LOWER 40S
BUT WOULD NOT BE SURPRISED TO SEE READINGS DIPPING INTO THE 30S
EITHER OF THOSE NIGHTS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 743 AM EDT MON SEP 1 2014
IWD...ALTHOUGH THERE MAY BE SOME BREAKS IN THE SHRA...MVFR
CONDITIONS WL PREDOMINATE EARLY. THE CIGS ARE LIKELY TO FALL INTO THE IFR
RANGE BRIEFLY DURING MID MRNG AS THE FRONT PASSES AND THE WIND SHIFTS
TO AN UPSLOPE WNW DIRECTION. THE W WIND BEHIND THE FROPA WILL TAP
DRIER AIR AND ALLOW FOR CONDITIONS TO IMPROVE TO VFR DURING THE AFTN.
CMX...MVFR CONDITIONS WILL PREDOMINATE EARLY WITH PERIODS OF SHOWERS.
A WSHFT TO AN UPSLOPE W DIRECTION BEHIND A FROPA AND WITH SOME
CONTINUED -SHRA SHOULD RESULT IN A PERIOD OF IFR CONDITIONS DURING THE
LATE MRNG/EARLY AFTN BEFORE THE W WIND TAPS DRIER AIR AND RESULTS IN
IMPROVEMENT TO VFR BY LATE IN THE DAY.
SAW...EXPECT IFR CIGS TO PERSIST THIS MORNING WITH ABUNDANT LOW
LEVEL MOISTURE AND UPSLOPE SRLY FLOW. EXPECT SOME SHRA WITH MVFR
CONDITIONS TO DEVELOPP BY LATE MORNING WITH THE APPROACH OF A SFC
COLD FRONT. EXPECT IMPROVEMENT LATE IN THE AFTERNOON WITH A WSHFT TO
A DOWNSLOPE W DIRECTION AND THE ARRIVAL OF DRIER AIR FOLLOWING THE
FROPA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT MON SEP 1 2014
WINDS WILL BE 20 KNOTS OR LESS THROUGH THIS FORECAST PERIOD WITH
AREAS OF FOG PERSISTING UNTIL DRIER AIR MOVES INTO THE REGION
TONIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1050 AM CDT MON SEP 1 2014
.AVIATION/18Z TAFS/...LOW PRESSURE LIFTING NORTHEAST FROM LAKE
SUPERIOR WITH TRAILING COLD FRONT INTO NW WI THROUGH CNTRL IA.
AIRMASS QUITE STABLE ATTM AHEAD OF THIS FRONT WITH JUST A COUPLE
BATCHES OF SHRA. CLOUD COVER IS EXTENSIVE AND PRIMARY
SHORTWAVE/SPEED MAX LIFTING NORTHEAST. EXTENSIVE CLOUD COVER
UPSTREAM LIKELY TO KEEP INSTABILITY FROM GETTING OUT OF
HAND....THOUGH SOME HERE AND THERE. SO WHILE FRONT IS YET TO WORK
THROUGH...SVR CONVECTIVE DEVELOPMENT NOT LIKELY. MESO MODELS
CONTINUE TO PULL BACK ON STORM STRENGTH THIS AFTN/EVE...SO AGREE
WITH SPC/S REMOVAL OF SLGT RISK FROM SRN WI. EXPECT MVFR CIGS TO
LINGER INTO THE AFTERNOON WITH THE VERY MOIST LOW LEVELS AHEAD OF
THE COLD FRONT. SOME IMPROVEMENT OF THESE CIGS INTO THIS EVENING
ONCE SFC COLD FRONT WORKS THROUGH AND DRIER NW WINDS KICK IN.
WEAK HIGH BUILDS IN TNGT WITH SFC TROUGH POSSIBLY GENERATING A FEW
SHRA TUE AFTN.
PC
&&
.PREV DISCUSSION... /ISSUED 355 AM CDT MON SEP 1 2014/
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
AREA OF RAIN SHOWERS AND A FEW THUNDERSTORMS OVER SOUTHWEST
WISCONSIN...INTO FAR EASTERN IOWA AND FAR NORTHWEST ILLINOIS...HAS
BEEN SLOWLY WEAKENING OVER THE PAST FEW HOURS. THIS WAS BEING DRIVEN
BY 500 MB VORTICITY MAXIMUM MOVING INTO THE AREA...UPPER DIVERGENCE
WITH RIGHT REAR QUADRANT OF 250 MB JET STREAK...ALONG WITH 850 MB
LOW LEVEL JET. SPC MESOANALYSIS PAGE SHOWING A GOOD AMOUNT OF
CONVECTIVE INHIBITION OVER THE AREA...WHICH MAY BE HELPING WEAKEN
CONVECTION.
STILL...THE ABOVE MAIN FEATURES SHOULD CONTINUE TO BRING SOME
SHOWERS ACROSS THE AREA THROUGH THE MIDDLE MORNING HOURS. THIS IS
SUPPORTED BY THE HRRR AND OTHER MESOSCALE MODELS...THOUGH THEY AREA
SOMEWHAT OVERDONE WITH CURRENT PRECIPITATION TRENDS. THUS...WILL
CONTINUE HIGH POPS THROUGH THE MIDDLE MORNING HOURS FOR SHOWERS AND
ISOLATED STORMS.
MAIN ISSUE WILL BE CONVECTIVE TRENDS THIS AFTERNOON AND EVENING WITH
PASSING COLD FRONT AND SEVERE WEATHER POSSIBILITIES. COLD FRONT WILL
PASS EAST THROUGH THE AREA THIS AFTERNOON...EXITING THE SOUTHEAST BY
MIDDLE TO LATE EVENING. SYNOPTIC MODELS VARY A BIT IN THE TIMING OF
THE FRONT. FRONTOGENESIS RESPONSE WITH FRONT IS WEAK AS IT MOVES
THROUGH THE AREA...THOUGH ELONGATED 500 MB VORTICITY MAXIMUM PUSHES
INTO THE AREA FROM THE WEST. WENT WITH CHANCE POPS FOR THIS
AFTERNOON...AND EVENING IN THE SOUTHEAST...AS THERE IS SOME
UNCERTAINTY WITH THE AREAL COVERAGE OF CONVECTION WITH THE FRONT.
IF MORNING PRECIPITATION CAN MOVE OUT AND CLOUDS BREAK UP THIS
AFTERNOON...SHOULD SEE AT LEAST 1000 TO 1500 J/KG OF MEAN LAYER CAPE
AND AROUND 50 KNOTS OR SO OF DEEP LAYER SHEAR. THIS IS CERTAINLY
SUPPORTIVE OF SEVERE CONVECTION...WITH LARGE HAIL AND DAMAGING WINDS
POSSIBLE. SPC HAS MOST OF THE AREA IN A SLIGHT RISK FOR SEVERE
STORMS THIS AFTERNOON AND EARLY THIS EVENING.
DRIER AIR WORKS INTO THE AREA LATER TONIGHT...BRINGING QUIETER
WEATHER. HIGHS TODAY WILL DEPEND ON AMOUNT OF CLOUDS LINGERING FROM
MORNING PRECIPITATION. WENT WITH UPPER 70S TO LOWER 80S FOR NOW.
LOWS TONIGHT SHOULD DROP INTO THE UPPER 50S TO LOWER/MID 60S.
TUESDAY AND WEDNESDAY...FORECAST CONFIDENCE...HIGH
IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY AS SURFACE HIGH PRESSURE
SLIDES THROUGH THE AREA. DID ADD A SLIGHT CHANCE FOR
SHOWERS/STORMS IN THE NORTH TUESDAY...AS MODELS NOW IN DECENT
AGREEMENT WITH A WEAK SHORTWAVE PASSING THROUGH. WARM TEMPS WILL
CONTINUE BOTH DAYS WITH HIGHS NEAR TO A FEW DEGREES ABOVE NORMAL.
WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM
BUMPED POPS UP WEDNESDAY NIGHT...AS MODELS ARE IN PRETTY GOOD
AGREEMENT IN BRINGING STRONG WARM AIR ADVECTION INTO SOUTHERN
WISCONSIN ON THE NOSE OF A 40-50 KT LLJ. LOOKS LIKE A SHORTWAVE
WILL ALSO BE MOVING THROUGH...WHICH SHOULD HELP TO FIRE OFF SOME
SHOWERS/STORMS.
THE PRECIP MAY HANG ON INTO THURSDAY MORNING...WITH MOST MODELS
THEN SHOWING A DRIER AND VERY WARM AFTERNOON IF THE SUN CAN COME
OUT. MODEL 925 MB TEMPS GET UP TO AROUND 25-26C...WHICH WOULD
RESULT IN HIGHS AROUND 90 GIVEN ENOUGH SUN. THROW IN DEWPOINTS IN
THE LOW 70S AND IT COULD END UP BEING AN UNCOMFORTABLE EARLY
SEPTEMBER DAY.
THE COLD FRONT IS EXPECTED TO MOVE THROUGH THURSDAY
NIGHT...BRINGING MORE THUNDERSTORM CHANCES. LINGERED SOME POPS
INTO FRIDAY DUE TO A COUPLE MODELS BEING A BIT SLOWER WITH THE
TIMING OF THE FRONT AND SHORTWAVE. SHOULD SEE HIGH TEMPS BACK DOWN
TO AROUND NORMAL FOR FRIDAY.
SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM
IT LOOKS COOLER AND DRY SATURDAY AND SUNDAY AS HIGH PRESSURE
SETTLES INTO THE GREAT LAKES REGION. TEMPERATURES WILL LIKELY BE
A FEW DEGREES BELOW NORMAL IF CURRENT MODEL FORECASTS VERIFY.
AVIATION/12Z TAFS/...
AREA OF SHOWERS AND A FEW STORMS WILL SHIFT EAST NORTHEAST THROUGH
THE AREA INTO THE MIDDLE MORNING HOURS. MAY SEE MVFR VISIBILITIES
AND CEILINGS WITH THESE SHOWERS. GUSTY SOUTH SOUTHWEST WINDS ARE
EXPECTED BY THE AFTERNOON HOURS...WITH GUSTS TO 25 KNOTS AT TIMES.
COLD FRONT WILL PUSH EASTWARD THROUGH TAF SITES BETWEEN 21Z TODAY
AND 03Z TUESDAY. SHOWERS AND STORMS ARE POSSIBLE ALONG AND AHEAD OF
THE FRONT. STRONG/SEVERE STORMS ARE POSSIBLE WITH HAIL AND GUSTY
WINDS. UNCERTAINTY EXISTS WITH THE AREAL COVERAGE OF STORMS...SO
WILL JUST USE VICINITY THUNDER WORDING FOR NOW IN TAFS. MVFR/IFR
VISIBILITIES AND CEILINGS ARE POSSIBLE IN ANY STORMS.
QUIET WEATHER WILL RETURN AFTER THE FRONTAL PASSAGE AND LINGER
THROUGH THE REST OF TONIGHT. LIGHT WINDS AND LINGERING MOISTURE MAY
BRING MVFR/IFR FOG AND CEILINGS TO THE AREA AFTER 06Z TUESDAY.
MARINE...
CANCELLED MARINE DENSE FOG ADVISORY EARLY...AS INCREASING SOUTH
WINDS SHOULD MIX OUT ANY LINGERING FOG NORTH OF NORTH POINT
LIGHTHOUSE.
SMALL CRAFT ADVISORY CONTINUES FOR THE NEARSHORE WATERS FROM 15Z
UNTIL 23Z TODAY. TIGHT PRESSURE GRADIENT WILL ALLOW FOR GUSTY SOUTH
SOUTHWEST WINDS TO 25 KNOTS AT TIMES. THIS WILL BRING WAVES OF 3 TO
5 FEET TOWARD THE OPEN WATERS. WINDS AND WAVES WILL SUBSIDE BY THIS
EVENING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...WOOD
TUESDAY THROUGH SUNDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
618 AM CDT MON SEP 1 2014
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 308 AM CDT MON SEP 1 2014
WATER VAPOR SATELLITE LOOP COUPLED WITH RAP ANALYSIS SHOWS VIGOROUS
MID-LEVEL TROUGH ROTATING THROUGH THE PLAINS TOWARD THE UPPER
MISSISSIPPI RIVER VALLEY. AT THE SURFACE 999MB LOWS WAS OVER WESTERN
ONTARIO WITH A COLD FRONT EXTENDING SOUTHWARD THROUGH MN/NW
IA/CENTRAL NEB. RADAR WAS LIT UP WITH SHOWERS/THUNDERSTORMS ACROSS
EASTERN MN INTO THE FORECAST AREA AHEAD OF THE MID-LEVEL WAVE AND
SURFACE COLD FRONT. OTHERWISE...TEMPERATURES ACROSS THE AREA EARLY
THIS MORNING WERE IN THE 60S.
LOOK FOR THE SURFACE COLD FRONT AND ASSOCIATED CONVECTION TO
CONTINUE PUSHING EAST ACROSS THE AREA THIS MORNING WITH THE BULK OF
THE RAIN EXITING EAST BY LATE MORNING. KEPT LINGERING AND
DIMINISHING CHANCES GOING HOWEVER INTO THE AFTERNOON AS THE MID-
LEVEL TROUGH/COLD AIR ALOFT POSSIBLY POPPING A FEW INSTABILITY
SHOWERS AND THUNDERSTORMS. NOT EXPECTING ANY SEVERE THREAT AS BEST
CAPE AND WIND SHEAR SHIFT EAST/SOUTHEAST OF THE AREA.
FOR TONIGHT...WILL SEE ANOTHER WEAK MID-LEVEL WAVE ROTATE TOWARD THE
AREA FROM THE NORTHERN PLAINS. NAM SHOWING A DECENT SHOT OF 700-
300MB PVA MOVING IN MAINLY WEST OF THE MISSISSIPPI RIVER AFTER
MIDNIGHT WITH BUFKIT SHOWING INSTABILITY/MOISTURE MAINLY CONFINED
ABOVE 800MB. KEPT A SMALL-END CHANCE OF SHOWERS/ISOLATED WEST OF THE
MISSISSIPPI AFTER MIDNIGHT BASED ON THIS SIGNAL. OVERNIGHT LOWS ARE
EXPECTED TO FALL INTO THE 50S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 308 AM CDT MON SEP 1 2014
A SMALL CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO
TUESDAY MAINLY NORTH OF I-94 AS THE WEAK MID-LEVEL TROUGH ROTATES
ACROSS THE FORECAST AREA. PLAN ON HIGHS RANGING FROM THE MIDDLE 70S
ACROSS NORTH CENTRAL WI...TO THE UPPER 70S/LOWER 80S ELSEWHERE.
SURFACE CYCLOGENESIS OVER THE NORTHERN PLAINS WILL PUSH A WARM FRONT
TOWARD THE AREA WEDNESDAY/WEDNESDAY NIGHT. ALL MODELS SHOW
INCREASING 850MB MOISTURE TRANSPORT/WARM AIR ADVECTION NOSING INTO
THE AREA WITH THE FRONT FOR INCREASING COVERAGE OF THUNDERSTORMS.
PRECIPITABLE WATER VALUES PUSHING 1.9 INCHES BY THURSDAY MORNING WITH
WARM CLOUD DEPTH LAYERS INCREASING INTO THE 4-4.5KM RANGE. BASED ON
THIS SIGNAL...WILL HAVE TO WATCH FOR A HEAVY RAINFALL POTENTIAL
ALONG WITH OTHER SEVERE THREATS AS WELL AS CAPE AND BULK SHEAR
INCREASE ALONG THE WARM FRONT. AT THIS POINT...MODELS SHOWING HIGHER
SEVERE POTENTIAL STAYING WEST OF THE MISSISSIPPI RIVER IN MORE
FAVORABLE CAPE/SHEAR ENVIRONMENT. WILL HAVE TO KEEP A CLOSE ON THIS
OVER THE NEXT COUPLE DAYS. LOOK FOR HIGHS ON WEDNESDAY TO TOP OFF IN
THE UPPER 70S TO MIDDLE 80S WITH DEW POINTS CREEPING UP INTO THE 65-
70 DEGREE RANGE.
THUNDERSTORM CHANCES CONTINUE THURSDAY INTO THURSDAY NIGHT AS THE
LOW PULLS NORTHEAST INTO ONTARIO CANADA...PUSHING A COLD FRONT
THROUGH THE AREA. THURSDAY WILL HAVE TO BE WATCHED CLOSELY AS WELL
FOR SEVERE POTENTIAL AS THE GFS IS SHOWING 0-6KM BULK SHEAR OF 30-
50KT COUPLED WITH MUCAPE POOL OF 2500-4500J/KG. HIGHS ON THURSDAY
AHEAD OF THE COLD FRONT ARE EXPECTED TO TOP OFF WELL INTO THE 80S
WITH DEW POINTS IN THE 70-75 DEGREE RANGE.
DRIER/COOLER AIR FILTERS INTO THE AREA FRIDAY AND INTO THE WEEKEND
AS CANADIAN HIGH PRESSURE BUILD INTO THE REGION. PLAN ON
TEMPERATURES BY THIS WEEKEND TO FEEL A BIT MORE LIKE FALL WITH HIGHS
IN THE 60S/LOWER 70S AND LOWS IN THE 50S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 618 AM CDT MON SEP 1 2014
SECOND ROUND OF CONVECTION HAS FORMED AHEAD OF THE FRONT AND
EXPECT THIS TO MOVE THROUGH BEFORE 12Z AT KRST AND KLSE BY 14Z.
IFR CONDITIONS WILL BE POSSIBLE IN THIS ACTIVITY. THE FRONT IS
THEN EXPECTED TO PUSH THROUGH SHORTLY BEHIND THE CONVECTION
SWINGING THE WINDS AROUND TO THE WEST AND ALLOWING AN AREA OF MVFR
CEILINGS TO MOVE IN. BOTH THE 01.06Z NAM AND 01.09Z RAP SUGGEST
THESE CEILINGS WILL ONLY LAST THROUGH THE MORNING BEFORE
SCATTERING OUT WITH VFR CONDITIONS THEN EXPECTED THROUGH THE REST
OF THE PERIOD. SOME CONCERN FOR FOG DEVELOPMENT LATE
TONIGHT...ESPECIALLY AT KLSE. FORECAST SOUNDINGS FROM THE NAM
INDICATE SATURATION MAY OCCUR AT THE SURFACE WITH A LIGHT WIND
PROFILE UP THROUGH ABOUT 25OO FEET OR SO. HOWEVER...UNSURE HOW
MUCH MID AND HIGH LEVEL CLOUDS MAY BE AROUND AHEAD OF AN
APPROACHING WEAK SHORT WAVE TROUGH. WILL LET LATER SHIFTS ACCESS
THIS POTENTIAL AND ADD IF NEEDED.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS PUEBLO CO
311 PM MDT MON SEP 1 2014
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 240 PM MDT MON SEP 1 2014
MAIN NEAR/SHORT-TERM METEOROLOGICAL ISSUES ARE
TEMPERATURES...LOCALIZED GUSTY WINDS AT TIMES AND LOCALIZED LOW-
GRADE POPS.
CWFA EXPERIENCING NEAR SEASONAL SEPTEMBER AFTERNOON TEMPERATURES IN
COMBINATION WITH GENERALLY SUNNY SKIES...ALTHOUGH SOME VARIABLE
CLOUDS NOTED OVER PRIMARILY HIGHER TERRAIN LOCATIONS.
IN ADDITION...WIND GUSTS EXCEEDING 30 MPH AT TIMES HAVE BEEN
OBSERVED OVER THE MOUNTAINS OF CHAFFEE COUNTY. RECENT RADAR RETURNS
INDICATE SHOWERS AND THUNDERSTORMS NEARING FAR NORTHEASTERN
COLORADO...WELL NORTH OF OUR CWFA.
LATEST COMPUTER SIMULATIONS...REAL-TIME DATA AND FORECAST MODEL
SOUNDINGS INDICATE THAT GENERALLY DRY CONDITIONS SHOULD CONTINUE
OVER THE MAJORITY OF THE FORECAST DISTRICT FROM LATE THIS AFTERNOON
INTO TUESDAY AFTERNOON...ALTHOUGH RECENT HRRR MODEL DATA SUGGESTS
THAT SHOWERS AND THUNDERSTORMS MAY THREATEN PORTIONS OF NORTHERN EL
PASO AND KIOWA COUNTIES AS WELL AS SECTIONS OF LAS ANIMAS AND BACA
COUNTIES FROM LATER THIS AFTERNOON INTO THIS EVENING.
FOR TUESDAY...THE HIGHEST PROBABILITY OF ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY SHOULD BE NOTED OVER WESTERN HIGHER TERRAIN
LOCATIONS...PRIMARILY DURING THE AFTERNOON AND EVENING HOURS.
GUSTY...PRIMARILY HIGHER TERRAIN WINDS ARE ALSO ANTICIPATED AT TIMES
FROM LATER THIS AFTERNOON INTO TUESDAY WHILE ABOVE SEASONAL EARLY
SEPTEMBER AFTERNOON TEMPERATURES ARE PROJECTED TUESDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 240 PM MDT MON SEP 1 2014
...HOT WITH LOW THUNDERSTORM CHANCES THROUGH EARLY THURSDAY THEN
COOLER WITH INCREASING THUNDERSTORM CHANCES...
TUESDAY EVENING INTO EARLY THURSDAY...THE AIR MASS OVER THE REGION
WILL BE QUITE WARM AND THE THUNDERSTORM CHANCES WILL BE LOW. COULD
BE SOME SPOTTY DRY THUNDERSTORMS AROUND TUESDAY EVENING...MAINLY
OVER THE MOUNTAINS. THEN...WEDNESDAY AFTERNOON...COULD BE SOME
SPOTTY DRY LINE ACTIVITY ACROSS THE FAR SOUTHEAST PLAINS. MODELS
HAVE BEEN BACK AND FORTH ON THIS SO CONFIDENCE IS A LITTLE LOW BUT
THE POSSIBILITY REMAINS ALIVE.
ON THURSDAY...THINGS START TO TRANSITION TO A COOLER...WETTER
PATTERN. MODELS HAVE BEEN PRETTY CONSISTENT ON THIS SO CONFIDENCE
IS INCREASING. IT STARTS WITH THE ARRIVAL OF A COLD FRONT THROUGH
THE EASTERN PLAINS THURSDAY AFTERNOON. THE FRONT PUSHES INTO THE
REGION AS THE RESULT OF AN UPPER DISTURBANCE MOVING THROUGH THE
NORTHERN ROCKIES AND PLAINS. AS THE FRONT MOVES IN...MOIST UPSLOPE
WINDS BEHIND THE FRONT GRADUALLY FIRE THUNDERSTORMS OVER AND NEAR
THE MOUNTAINS IN THE AFTERNOON...SOME OF WHICH WORK EAST ACROSS THE
PLAINS BY LATE IN THE DAY. WITH ADDED MOISTURE IN THE AIR AND
UPSLOPE WINDS...THE THREAT FOR STRONG STORMS WILL INCREASE THIS DAY.
FRIDAY THROUGH MONDAY...WE COULD BE DEALING WITH SOME RICH
SUBTROPICAL MOISTURE AT TIMES...JUST DEPENDING ON HOW THINGS TRACK
OVER THE NEXT FEW DAYS. RIGHT NOW...INDICATIONS ARE THAT FRIDAY AND
SATURDAY COULD BOTH BE PRETTY WET OVER THE REGION WITH CONCERNS OF
FLASH FLOODING. SUNDAY AND MONDAY STILL LOOK PRETTY WET FOR THE
MOUNTAINS...BUT THE PLAINS LOOK MORE STABLE WITH LESS ACTIVITY. ALL
OF THIS IS STILL SEVERAL DAYS AWAY AND HIGHLY SUBJECT TO
CHANGE...HOWEVER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 240 PM MDT MON SEP 1 2014
VFR CONDITIONS ARE ANTICIPATED AT THE KALS...KCOS AND KPUB TAF SITES
THROUGH TUESDAY AFTERNOON.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...77
LONG TERM...LW
AVIATION...LW
AREA FORECAST DISCUSSION
NWS MIAMI FL
130 PM EDT MON SEP 1 2014
.AVIATION...
MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST. SEA
BREEZE CIRCULATION APPEARS TO HAVE FINALLY SET UP ALONG THE EAST
COAST WITH MOST SHRA ACTIVITY DIMINISHING. STILL COULD HAVE ONE OR
TWO SHRA DEVELOP UNTIL AROUND 20Z BUT TOO ISOLATED TO PLACE
MENTION IN THE TAF AT THIS TIME. LATEST SHORT TERM HIGH RESOLUTION
GUIDANCE INDICATES CONVECTION WILL BEGIN TO FIRE ALONG THE
SOUTHWEST COAST BTWN 18-19Z SO KEPT MENTION OF VCTS IN THE KAPF
TAF. GUIDANCE ALSO INSISTING EAST FLOW TOO STRONG AND WILL INHIBIT
THE WEST COAST SEA BREEZE FROM SETTING UP BUT THE WIND AT KAPF MAY
BECOME MORE SSE AS THE CIRCULATION TRIES TO DEVELOP.
KOB
&&
.PREV DISCUSSION... /ISSUED 1021 AM EDT MON SEP 1 2014/
UPDATE...
THE LATEST WATER VAPOR IMAGERY INDICATES THE MID TO UPPER LEVEL
TROUGH CONTINUES TO RETROGRADE TO THE SOUTHWEST AND IS ENTERING
THE NORTHWEST BAHAMAS. THIS IS BRINGING IN SOME DRIER MID TO UPPER
LEVEL AIR INTO SOUTH FLORIDA AND ADJACENT WATERS THIS MORNING.
RECENT RADAR RETURNS INDICATE ISOLATED SHOWER ACTIVITY MAINLY
ACROSS THE ATLANTIC WATERS. MINOR UPDATES WERE DONE TO THE SHORT
TERM FORECAST TO REFLECT THE CURRENT CONDITIONS. BUT AS THE
AFOREMENTIONED TROUGH CONTINUES TO MOVE TO THE SOUTHWEST AND INTO
THE REGIONAL ATLANTIC WATERS...THAT WILL LIKELY ALLOW FOR SOME
POTENTIAL FOR CONVECTION. THERE IS CURRENTLY ACTIVE CONVECTION IN
THE NORTHWEST BAHAMAS ISLANDS. SO THE FORECAST REFLECTS SCATTERED
SHOWER/THUNDERSTORM ACTIVITY POSSIBLE OVER THE ATLANTIC WATERS
AND EAST COAST METRO AREAS LATER THIS AFTERNOON WITH GREATER
COVERAGE EXPECTED ACROSS THE WESTERN PENINSULA LATE THIS AFTERNOON
WHERE THE SURFACE CONVERGENCE WILL BE MOST DOMINANT. SO OVERALL NO
SIGNIFICANT CHANGES FROM PREVIOUS FORECAST OR SYNOPTIC REASONING
EXCEPT FOR THE VERY SHORT TERM.
60
PREV DISCUSSION... /ISSUED 728 AM EDT MON SEP 1 2014/
AVIATION...
MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST WITH A
MODERATE EAST WIND FLOW. ANTICIPATED TSRA DEVELOPMENT WILL BE OVER
THE INTERIOR WITH A WESTWARD PROPAGATION. AT THIS TIME, PLACED A
VCTS IN THE KAPF TAF AFT 19Z AND THEY COULD HAVE A BRIEF MVFR OR
EVEN IFR CIG/VSBY THROUGH THE AFTERNOON. EAST FLOW WILL PREVENT A
SEA BREEZE ALONG THE SOUTHWEST COAST BUT WIND IS LIKELY TO VEER TO
THE SSE AS IT TRIES TO FORM.
KOB
PREV DISCUSSION... /ISSUED 329 AM EDT MON SEP 1 2014/
HIGHLIGHTS...
* MODERATE RISK OF RIP CURRENTS ATLANTIC BEACHES
* SLIGHT TSTORM CHANCE EAST COAST, BETTER CHANCE GULF COAST TODAY
* STORMIER PATTERN MID-LATE WEEK; STRONG STORMS POSSIBLE
DISCUSSION...
THE WEATHER PATTERN ON THIS LABOR DAY WILL REMAIN
MOSTLY UNCHANGED FROM YESTERDAY. RIDGE AXIS WILL REMAIN OVER NORTH
FLORIDA, MAINTAINING AN EASTERLY WIND FLOW LOCALLY WITH CONVECTIVE
FOCUS ALONG THE GULF COAST IN THE AFTERNOON. LOW LEVEL WINDS WILL
BE STRONG ENOUGH TO DISALLOW A FULL GULF SEA BREEZE FROM
DEVELOPING, BUT SOME VEERING OF THE WIND FIELD IS EXPECTEDTHERE
WHICH AGAIN WILL LEAD TO ENOUGH CONVERGENCE TO SPARK SOME TSTORM
DEVELOPMENT. ACROSS THE EAST COAST, HRRR SHOWS A SCENARIO SIMILAR
TO YESTERDAY WITH QUICK PASSING SHOWERS DEVELOPING. CANNOT RULE
OUT TSTORMS EAST COAST BUT CONVERGENCE WILL BE LACKING SO COVERAGE
WOULD BE ISOLATED AT BEST.
LIKE YESTERDAY, A LIMITING FACTOR FOR MORE ACTIVE TSTORMS IS THE
LACK OF A FULL FLEDGED ONSHORE GULF SEA BREEZE. HOWEVER, CANNOT
RULE OUT A STRONG TSTORM OR TWO GIVEN SOME CONVERGENCE ALONG WITH
THE INSTABILITY AND CONTINUED DRY AIR ALOFT. WIND GUSTS OF 40-50
MPH IS THE PRIMARY THREAT.
A DEEP LAYERED TROUGH EAST OF THE BAHAMAS IS SHOWN BY THE GLOBAL
MODELS TO MOVE WEST AND ACROSS SOUTH FLORIDA WED NIGHT-THU. THIS
WILL BE ASSOCIATED WITH COOLING ALOFT ALONG WITH INCREASING
MOISTURE, SPELLING A STORMIER PERIOD MID WEEK AND EVEN INTO LATE
WEEK AS HIGHER INSTABILITY REMAINS. POPS ACCORDINGLY SHOW AN
UPWARD TREND MID-LATE WEEK. COULD SEE SOME STRONG STORMS ANYWHERE
BEGINNING WED THROUGH LATE WEEK DUE TO THE COLD AIR ALOFT AND
TROUGH PASSAGE, THOUGH MORE CLOUDINESS WOULD BE A LIMITING FACTOR.
/GREGORIA
AVIATION...
HIGH PRESSURE WILL SLOWLY WEAKEN OVER THE SOUTHEASTERN UNITED
STATES TODAY WHICH IN TURN WILL KEEP A EASTERLY WIND FLOW OF
AROUND 5 KNOTS THROUGH EARLY THIS MORNING AT ALL OF THE TAF SITES.
THE WIND DIRECTION WILL REMAIN EASTERLY AFTER 14Z TODAY BUT
INCREASE TO AROUND 10 KNOTS OVER ALL OF THE TAF SITES.
THE WEATHER SHOULD REMAIN DRY THROUGH THE EARLY MORNING HOURS BEFORE
SOME SHOWERS WORKS INTO THE EAST COAST TAF SITES AFTER 14Z.
SO WILL PUT IN VCSH AFTER 14Z FOR THE EAST COAST TAF SITES. FOR
KAPF TAF SITE...THE WEATHER WILL ALSO REMAIN DRY THROUGH MOST OF
THIS LABOR DAY. HOWEVER...A LATE WEST COAST SEA BREEZE COULD
DEVELOP AND PUSH INTO THE KAPF TAF SITE AFTER 21Z TODAY. SO WILL
PUT IN VCTS BETWEEN 21Z AND 00Z TODAY.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS AT ALL
OF THE TAF SITES FOR THIS LABOR DAY.
MARINE...EAST SOUTHEAST WINDS LESS THAN 15 KT WILL PREVAIL AS
THE ATLANTIC RIDGE REMAINS NORTH OF THE LOCAL WATERS. SEAS WILL BE
CORRESPONDINGLY LOW. A TROUGH WILL MOVE ACROSS THE WATERS LATE
WED- THU, BRINGING AN INCREASING CHANCE OF THUNDERSTORMS
ESPECIALLY ACROSS THE ATLANTIC WATERS.
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
149 PM EDT MON SEP 1 2014
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL EXTEND INTO THE FORECAST AREA FROM THE
ATLANTIC THROUGH THE MIDDLE OF THE WEEK. A PERSISTENT UPPER RIDGE
WILL HELP MAINTAIN THE HOT TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
VISIBLE IMAGERY EARLY THIS AFTERNOON SHOWING LESS CUMULUS COVERAGE
THAN 24 HOURS AGO AND THIS MAY BE ATTRIBUTED TO HIGHER CONVECTIVE
TEMPS IN THE MID 90S TODAY...SOME DRIER AIR NOTED AT 850MB...AND
PRECIPITABLE WATER VALUES AROUND 1.7 INCHES. ENHANCED CUMULUS AND
SOME ISOLATED SHOWERS BEING OBSERVED OVER CENTRAL GEORGIA WHERE
MOISTURE IS BETTER. CURRENTLY WEAK INSTABILITY ACROSS THE AREA
WITH LIFTED INDEX VALUES AROUND -3C TO -5C BUT LAPSE RATES
CONTINUE TO RISE AND ARE UP TO 7.5 C/KM.
SUCCESSIVE RUNS OF THE HRRR CONTINUE TO SHOW LITTLE CONVECTION
OVER THE FORECAST AREA LATE THIS AFTERNOON AND TONIGHT...WHILE THE
LATEST 12Z SPC WRF RUN IS VERY SIMILAR TO ITS 00Z RUN SHOWING
CONVECTION DEVELOPING IN THE CSRA AND WESTERN MIDLANDS LATE
AFTERNOON AND DRIFTING SOUTHEAST AND MERGING WITH SEA BREEZE
CONVECTION OVER THE LOWER CSRA AND SOUTHEASTERN MIDLANDS. WILL
MAINTAIN SLIGHT CHANCE POPS ACROSS THE NORTHERN AND CENTRAL
MIDLANDS WHILE KEEPING LOW CHANCE POPS IN THE MORE FAVORABLE AREA
OF THE CSRA AND SOUTHEASTERN MIDLANDS 21Z-02Z. CANNOT RULE OUT AN
ISOLATED SEVERE THUNDERSTORM AND WEAK STORM MOTION WILL PROVIDE A
LOCALLY HEAVY RAIN AND POSSIBLE FLOODING THREAT WHERE STORMS TRAIN
OR REMAIN NEARLY STATIONARY. EXPECT SOME CONVECTIVE DEBRIS CLOUDS
AROUND OVERNIGHT WHICH WILL HELP LIMIT FOG POTENTIAL AND EXPECT
OVERNIGHT LOWS IN THE MID 70S.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
SURFACE RIDGING SHOULD CONTINUE EAST AND SOUTH OF THE FORECAST
AREA. EXPECT WEAK LEE-SIDE TROUGHING IN THE AREA. STRONG HEATING
AND CONVERGENCE INTO THIS FEATURE SHOULD HELP SUPPORT
THUNDERSTORMS...BUT CONTINUED UPPER RIDGING SHOULD LIMIT COVERAGE.
ALSO...THE SURFACE FEATURE SHOULD REMAIN WEAK. THE NAM AND GFS
MOS HAVE LOW POPS WITH THE CONSENSUS AROUND 20 PERCENT. IT WILL
REMAIN HOT. USED THE WARMER TEMPERATURE GUIDANCE BASED ON RECENT
VERIFICATION.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A WEAKENING FRONT STALLING BEFORE REACHING
THE AREA DURING THE MIDDLE OF THE WEEK. THE MODELS SHOW ANOTHER
FRONT MAY REACH THE AREA LATE IN THE MEDIUM-RANGE PERIOD. THE
MODELS INDICATE UPPER-LEVEL RIDGING CONTINUING. THE
GFS...ECMWF...AND EKD MOS SHOW ABOVE NORMAL TEMPERATURES WITH POPS
20 TO 30 PERCENT THROUGH THE PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGHER CONVECTIVE TEMPS TODAY ALONG WITH SOME DRIER AIR AT 850MB
HAS RESULTED IN A LATER START TO THE CUMULUS DEVELOPMENT BUT IT IS
UNDERWAY WITH WEAK TO MODERATE INSTABILITY IN PLACE. ISOLATED
CONVECTION IS EXPECTED BUT LOW CONFIDENCE IN ANY STORMS IMPACTING
TERMINALS SO NOT IN THE FORECAST AT THIS TIME. EXPECT VFR
CONDITIONS THROUGHOUT THE FORECAST PERIOD EXCEPT FOR SOME MVFR FOG
AT FOG PRONE AGS/OGB...FOG APPEARS LESS LIKELY AT CAE/CUB/DNL.
LIGHT SOUTHERLY WINDS THIS AFTERNOON WILL BECOME NEAR CALM
OVERNIGHT AND PICK UP FROM THE SOUTH AGAIN AFTER 15Z TUESDAY...LESS
THAN 5 KNOTS.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN LATE NIGHT
AND EARLY MORNING STRATUS AND FOG. SCATTERED MAINLY AFTERNOON
SHOWERS AND THUNDERSTORMS TUESDAY THROUGH SATURDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
NEAR TERM...HC
AVIATION...HC
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
104 PM CDT MON SEP 1 2014
.DISCUSSION...
1115 AM CDT
FOR MORNING UPDATE...
THUNDERSTORM AND SEVERE WEATHER THREAT APPEARS TO HAVE DIMINISHED
SIGNIFICANTLY FOR MUCH OF THE FORECAST AREA TODAY...DUE TO CLOUD
COVER AND DRIER AIR WHICH HAS SPREAD EAST ACROSS NORTHERN IL WITH
OUTFLOW FROM OVERNIGHT MCS TO OUR WEST. SEE UPDATED SPC DAY 1
OUTLOOK WHICH REMOVES SLIGHT RISK GENERALLY ALONG/WEST OF I-57.
HAVE ALSO BOOSTED TEMPS ACROSS THE SOUTHEAST TO THE LOW-MID 80S
WHERE TEMPS QUICKLY WARMING.
LEAD SHORT WAVE...POSSIBLY ENHANCED BY MCS/MCV FROM NOCTURNAL MCS
OVER IOWA...HAS MOVED INTO NORTHERN IL THIS MORNING ACCOMPANIED BY A
PRE-FRONTAL TROUGH AND SHIFT TO WESTERLY WINDS GENERALLY WEST OF THE
FOX RIVER VALLEY AS OF 11 AM. EXTENSIVE CLOUD COVER..AND LOWER SFC
DEW POINTS BEHIND THE BOUNDARY HAVE STABILIZED ATMOSPHERE...WITH
HIGHER THETA-E AIR CHARACTERIZED BY LOWER 70S DEW POINT TEMPS NOW
MAINLY ALONG/EAST OF THE INTERSTATE 57 CORRIDOR. WHILE SOME EROSION
OF CLOUD COVER WAS NOTED ACROSS WESTERN IL...IT APPEARS THAT THE
MAIN INSTABILITY AXIS WILL BE ACROSS THE FAR EASTERN CWA AND AREAS
FARTHER EAST. HIGH-RES CONVECTION ALLOWING GUIDANCE INCLUDING THE
HRRR AND NATIONAL/LOCAL ARW RUNS INDICATE LITTLE IN THE WAY OF
ROBUST CONVECTION DEVELOPING ACROSS NORTHERN IL...WITH DIURNAL
DESTABILIZATION AND STRONGER THUNDERSTORM INITIATION FOCUSED EARLY
THIS AFTERNOON ALONG OUR EASTERN CWA BOUNDARY. THUS IT APPEARS OUR
SEVERE WEATHER THREAT HAS DECREASED SIGNIFICANTLY...AND SPC HAS
REMOVED MUCH OF THE CWA WEST OF I-57 FROM THEIR DAY 1 SLIGHT RISK.
THE SYNOPTIC COLD FRONT STILL REMAINS TO OUR WEST...FROM JUST EAST
OF THE TWIN CITIES TO SOUTHWEST IOWA AT 11 AM...AND THIS WILL MOVE
EAST THROUGH THE AFTERNOON AND EVENING. GUIDANCE DOES DEPICT A LINE
OF SHOWERS/ISOLATED THUNDERSTORMS DEVELOPING AHEAD OF THE FRONT LATE
THIS AFTERNOON AND EVENING...THOUGH SEVERE THREAT APPEARS VERY LOW
IN RATHER WEAK MLCAPE ENVIRONMENT. POTENTIAL FOR STRONGER STORM
DEVELOPMENT DOES REMAIN LATER TONIGHT ALONG THE FRONT AS MAIN SHORT
WAVE MOVES ACROSS THE AREA...THOUGH TRENDS FROM 12Z GUIDANCE
INDICATE ONLY A SMALL PORTION OF OUR SOUTHEAST CWA MAY BE
AFFECTED. HAVE TRIMMED BACK POPS QUITE A BIT ACROSS THE NORTHERN
3/4 OR SO OF THE CWA AND MAY BE ABLE TO TRIM EVEN FURTHER
DEPENDING ON TRENDS OVER THE NEXT FEW HOURS.
RATZER
//PREV DISCUSSION...
340 AM CDT
ENTERING SEPTEMBER AND METEOROLOGICAL AUTUMN WE STILL FIND THE
FORECAST CHALLENGES TO BE MORE SUMMER-LIKE...AT LEAST EARLY ON IN
THE FORECAST. THAT IS STORM AND HEAVY RAIN POTENTIAL TODAY AND
TONIGHT...THEN STORM CHANCES WEDNESDAY NIGHT AND FRIDAY WHICH
SANDWICH A POSSIBLE 90 PLUS DEGREE DAY ON THURSDAY. LESS BUT
STILL SOME TIME WAS SPENT ON THE FINAL CHALLENGE OF HOW MUCH OF A
COOL DOWN OCCURS THE FIRST FULL WEEKEND OF THIS NEW METEOROLOGICAL
SEASON.
SYNOPSIS...
A LONG WAVE TROUGH EXTENDING SOUTHWARD THROUGH CANADA INTO THE NORTH
CENTRAL U.S. HAS A VERY PROGRESSIVE SHORT WAVE FEATURE MOVING
THROUGH ITS SOUTHERN BASE. THIS IS SPEEDING EAST-NORTHEAST ACROSS
IA EARLY THIS MORNING. A SURFACE COLD FRONT MOVING EAST LAGS THIS
SHORT WAVE...EXTENDING FROM NORTHERN MN THROUGH THE TX PANHANDLE
EARLY THIS MORNING...WITH MULTIPLE SURFACE WAVES IN THE 1003MB
NEIGHBORHOOD ALONG IT. NORTHWEST SURFACE FLOW BEHIND THIS FRONT IS
NOT PARTICULARLY STRONG SO THIS FRONT WILL CONTINUE TO BE A SLOW-
MOVER TODAY...NOT EXPECTED TO ENTER THE FORECAST AREA UNTIL THIS
EVE. BEING WITHIN A WARM SECTOR UNDER QUICKENING UPPER/MID-LEVEL
FLOW PRESENTS THE STORM CHANCES THESE 24 HOURS.
THIS MORNING...
A LOOSELY DEFINED MCS MOVING EASTWARD INTO NORTHWEST IL EARLY THIS
MORNING WANED CONSIDERABLY WITH WARMING CLOUD TOPS AND OUTFLOW
EXTENDING WELL AHEAD OF IT. SEEING AN UPTICK ACROSS WEST CENTRAL IL
LIKELY ASSOCIATED WITH LIFT OF THE AFOREMENTIONED PROGRESSIVE SHORT
WAVE. HIGH RESOLUTION MODELS GREATLY VARY ON WHAT WILL HAPPEN EVEN
JUST A FEW HOURS OUT...BUT WOULD EXPECT SYNOPTICALLY TO SEE SOME
CONVECTION EVOLVE INTO THE FORECAST AREA THIS MORNING...POSSIBLY
ONLY THE WESTERN/SOUTHWESTERN AREA BUT STILL CANT RULE OUT SCATTERED
ACTIVITY MOVING EASTWARD THROUGH THE ENTIRE AREA INCLUDING
CHICAGO DURING MID/LATE MORNING. DESPITE A FAIRLY STRONG LOW-LEVEL
JET INTO ANY ACTIVITY...THE CONTINUED BROAD AREA OF STORMS ACROSS
EASTERN KS INTO WEST/SOUTHWEST MO THROUGH EARLY TO MID MORNING
SHOULD LESSEN MOISTURE TRANSPORT AND THUS ABILITY TO REALIZE STEEP
LAPSE RATES ALOFT FOR MORE ROBUST ACTIVITY...AND MAYBE EVEN
THUNDER IN GENERAL NORTH OF INTERSTATE 80.
THIS AFTERNOON AND TONIGHT...
DESPITE THIS BEING IN THE FIRST 12 HOURS OF THE FORECAST...DUE TO
INFLUENCE OF MORNING STORMS AND LARGE MODEL DIFFERENCES...CONFIDENCE
ON SPECIFICS IN THESE PERIODS REMAIN LOW. THERE SHOULD BE SOME
FORM OF OUTFLOW BOUNDARY OR BOUNDARIES FROM MORNING ACTIVITY/CLOUD
COVER THAT LINGER INTO THE FORECAST AREA INTO THE AFTERNOON...MOST
FAVORED SOUTH OF INTERSTATE 80. AS WARMING AND DESTABILIZATION
OCCURS WITH DEW POINTS AROUND 70F...COULD SEE SCATTERED ACTIVITY
DEVELOP NEAR ANY SUCH BOUNDARIES DURING THE MID TO LATE AFTERNOON.
THE SECOND UPPER WAVE ACROSS WESTERN WY THIS MORNING WILL BEGIN TO
APPROACH THE REGION AS WELL BY LATE IN THE DAY...WITH FORCING FROM
THIS POSSIBLY AIDING IN SCATTERED STORM DEVELOPMENT ACROSS MUCH OF
THE REGION. EVEN EARLY THIS MORNING THERE ARE A HANDFUL OF STORMS
ACROSS THE UPPER MIDWEST NOT LINKED TO ANY SPECIFIC SURFACE
FEATURE. INCREASING DEEP LAYER SHEAR OF 35 TO 50 KT WILL SUPPORT
ISOLATED TO SCATTERED SEVERE DISCRETE STORMS IN THE REGION.
WHILE IT REMAINS DIFFICULT TO PINPOINT TIMING...IT WOULD SEEM THE
GREATEST COVERAGE IN REDEVELOPING STORMS THIS EVENING WOULD BE IN
THE SOUTHERN FORECAST AREA WHERE AFOREMENTIONED BOUNDARY MAY OCCUR
AND MODEST SOUTHWEST 850-925MB FLOW AND MOISTURE TRANSPORT
REMAINS. AS THE AREA BECOMES UNDER A RIGHT ENTRANCE REGION TO THE
UPPER JET...DO EXPECT INCREASING ASCENT TONIGHT IN THE REGION FOR
MORE ROBUST CONVECTION AND POTENTIAL SEVERE AND HEAVY RAIN
THREATS. RIGHT NOW A GUIDANCE OVERLAP WOULD INDICATE THE FAR
SOUTHEAST FORECAST AREA IS MOST FAVORED FOR THIS. PRECIPITABLE
WATERS AROUND TWO INCHES AND STORM MOTIONS NEARLY PARALLEL TO THE
UPPER AND MID LEVEL FLOW WILL PRESENT HEAVY RAIN THREATS IN
THE GENERAL CENTRAL TO SOUTHERN IL INTO IN REGIONS...BUT AGAIN AT
THIS TIME CONFIDENCE VARIES ON PLACEMENT. BECAUSE OF THAT WILL
CONTINUE WITH THE HYDROLOGIC OUTLOOK /ESF/ FOR THE AREAS HIT HARD
ON SATURDAY NIGHT WITH HEAVY RAINFALL.
TUESDAY AND WEDNESDAY...
THE FRONT SHOULD CLEAR THE FORECAST AREA SOMETIME TUESDAY MORNING.
WHILE DRY AIR ADVECTION WILL OCCUR...LIMITED CONVERGENCE REMAINS
IN THE SOUTHEAST FORECAST AREA FOR POSSIBLY A STORM OR TWO TUESDAY
BUT IT LOOKS TO BE A LOW CHANCE. TEMPERATURES ONLY COOL SLIGHTLY
AS HIGH PRESSURE QUICKLY MOVES ATOP THE AREA TUESDAY NIGHT AND
THEN EASTWARD.
WEDNESDAY NIGHT THROUGH FRIDAY...
WARM AIR ADVECTION AND A RAPID PRECIPITABLE WATER INCREASE IS
FORECAST WEDNESDAY NIGHT ON ALL GUIDANCE. FEEL THAT MODELS MAY BE
UNDER-DOING THE STORM CHANCES GIVEN FORECAST PROFILES OF STEEPENING
LAPSE RATES WITHIN A RAPIDLY MOISTENING COLUMN...AT LEAST IN THE
WESTERN FORECAST AREA. SO HAVE INCREASED POPS IN THAT AREA. AS FOR
THURSDAY...HAVE GONE DRY IN MANY AREAS COLLABORATING AND
UNDERCUTTING A MODEL BLEND OF POPS. THE SYNOPTIC PATTERN FAVORS A
HOT DAY AND BARRING ANY STRATUS ISSUES WITH WEDNESDAY NIGHTS WARM
AIR ADVECTION AND POSSIBLE PRECIP...SHOULD SEE THE 90 DEGREE MARK
REACHED OR EXCEEDED ACROSS A GOOD PART OF THE FORECAST AREA BASED
ON STRONG SOUTHWEST FLOW AND FORECAST 850MB AND 925MB TEMPERATURES
COMPARED TO CLIMATOLOGY. FOR NOW HAVE KEPT THE NORTH A LITTLE
BELOW THAT WITH THE POSSIBILITY OF MORNING CLOUDS. THE SYSTEM
COLD FRONT IS PRESENTLY FORECAST BY THE EC AND THE GFS TO COME
THROUGH THE AREA SOMETIME ON FRIDAY WHICH WOULD BRING STORM
CHANCES WITH IT...AS WELL AS FLOW TURNING OFF THE LAKE BEHIND ITS
PASSAGE.
BEYOND...
NO CHANGES MADE TO THIS WEEKEND WHERE HIGHS LOOK TO BE AROUND 70
WITH DRY CONDITIONS BEHIND THE AFOREMENTIONED FRONT. HIGH PRESSURE
AROUND 1023MB IS FORECAST BY A BLEND OF GUIDANCE. GIVEN THE 925MB
TEMPERATURES FORECAST IF THAT HIGH IS CENTERED OVER THE FORECAST
AREA SOMETIME SUNDAY OR MONDAY NIGHTS /7TH OR 8TH/...LOWS IN
OUTLYING AREAS WOULD LIKELY BE IN THE 40S.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* TSRA CHANCES THIS AFTERNOON AND EVENING.
* CEILING TRENDS THIS AFTERNOON.
* MORE SHRA AND TSRA POSSIBLE TOWARD EVENING.
LENNING
//DISCUSSION...UPDATED 18Z...
CONVECTION HAS BLOSSOMED ALONG A LINE OVER LOWER MI BUT MANAGED TO
AVOID MOST OF THE LOCAL AREA THIS MORNING. AN ADDITIONAL CLUSTER
OF STORMS IS STARTING TO FORM OVER NORTHEAST IOWA ALONG A COLD
FRONT THAT IS MOVING THIS DIRECTION. TIMING OF THE IOWA ACTIVITY
INTO THE LOCAL AREA IS UNCERTAIN...BUT FEEL THAT 00Z TO 03Z
IS A GOOD FIRST ESTIMATE AT ORD AND MDW AS PER 18Z TAF.
CEILINGS HAVE SCATTERED EXCEPT FOR SOME LINGERING MVFR...BUT AM
NOT CONFIDENT THAT SCT-CLR SKIES WILL BE WIDESPREAD THIS
AFTERNOON GIVEN THE AMOUNT OF MOISTURE IN THE AIR. AREAS THAT HAD
CLEARED EARLIER ARE ALREADY STARTING TO FILL BACK IN WITH DIURNAL
HEATING...BUT FOR THE MOST PART ARE STAYING VFR.
OVERNIGHT TOWARD MORNING THERE IS A CHANCE OF LOWER VSBYS WITH
LIGHT WINDS AND MOIST AIR IN PLACE...BUT GUIDANCE SHOWS BETTER
CHANCES TOWARD RFD THAN IN THE MDW/ORD TERMINALS...LIKELY DUE TO
BETTER COOLING THAN IN THE CITY. HAVE NOT PUT THIS IN THE TAFS YET
BUT WILL MONITOR FOR LATER INCLUSION.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM TO HIGH CONFIDENCE FOR ALL ELEMENTS.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH THURSDAY...PREDOMINANTLY VFR.
FRIDAY...CHANCE OF SHRA/TSRA.
SATURDAY AND SUNDAY...PREDOMINANTLY VFR.
KJB
&&
.MARINE...
232 AM CDT
IT LOOKS TO BE AN ACTIVE WEATHER DAY ACROSS THE LAKE...WITH STOUT
SOUTHERLY WINDS LAKE-WIDE...AND THE THREAT FOR SOME STRONG TO SEVERE
THUNDERSTORMS ACROSS SOUTHERN LAKE MICHIGAN. THESE STRONG SOUTHERLY
WINDS WILL RESULT IN WINDS AROUND 25 KT AND THE ONGOING SMALL CRAFT
ADVISORY STILL APPEARS GOOD. THE SURFACE LOW...RESPONSIBLE FOR THESE
STRONG SOUTHERLY WINDS TODAY...WILL SHIFT ACROSS ONTARIO...AND TO
NEAR JAMES BAY BY THIS EVENING WHILE DEEPENING TO AROUND 29.2
INCHES. AS THIS OCCURS...AN ASSOCIATED COLD FRONT WILL BE DRAWN
EASTWARD ACROSS THE LAKE BY EARLY TUESDAY MORNING. WINDS WILL BECOME
WESTERLY AND ABATE SIGNIFICANTLY WITH THE PASSAGE OF THIS FRONT.
ANOTHER PERIOD OF STRONGER SOUTHERLY WINDS LOOKS TO SET UP AGAIN
WEDNESDAY NIGHT AND THURSDAY AS ANOTHER POTENT AREA OF LOW PRESSURE
TRACKS EASTWARD ACROSS ONTARIO. WINDS SPEEDS COULD AGAIN BE AROUND
25 KT OUT OF THE SOUTH DURING THIS PERIOD. ANOTHER STRONGER COLD
FRONT LOOKS TO SHIFT DOWN THE LAKE IN THE WAKE OF THIS LOW LATE
FRIDAY AND THIS COULD SET THE STAGE FOR A DECENT NORTHERLY WIND
EVENT ACROSS THE LAKE AS A STOUT AREA OF HIGH PRESSURE QUICKLY
BUILDS EASTWARD ACROSS THE UPPER MIDWEST. STRONG NORTHERLY WINDS OF
25 TO 30 KT APPEAR QUITE POSSIBLE IN THE WAKE OF THIS COLD FRONT
FRIDAY NIGHT INTO SATURDAY...WHICH WOULD ALSO RESULT IN LARGE WAVES
IN EXCESS OF 5 FEET ACROSS SOUTHERN LAKE MICHIGAN INTO NEXT
WEEKEND.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM MONDAY.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1249 PM CDT Mon Sep 1 2014
.UPDATE...
ISSUED AT 1001 AM CDT MON SEP 1 2014
Line of strong to severe thunderstorms tracked across Iowa last
night, then rapidly dissipated as it pushed toward the
Mississippi River early this morning. Outflow boundary from this
dying convection is currently approaching the I-55 corridor
as evidenced by westerly winds across all sites in the Illinois
River Valley. Think this outflow will eventually serve as the
primary focus for additional thunderstorm development later today.
Still some question as to exactly where the boundary will lay out
and when convection will fire, but the latest thinking from SPC
has pushed the best severe weather risk much further southeast,
generally along/south of a Danville to Jacksonville line. HRRR is
performing very poorly this morning and its solution has been
completely disregarded. Meanwhile, the 12z NAM seems to have at
least a reasonable handle on the situation, showing storms
developing by early afternoon near I-55, then shifting further
east and south later in the day. Will continue to monitor
stability parameters to see if projected 1500 to 2500J/kg CAPEs
can be realized. If the airmass destabilizes as predicted,
increasing shear values will help storms organize and potentially
produce large hail and damaging winds this afternoon into this
evening. Am still concerned about the threat for heavy rainfall
across the E/SE CWA tonight as favorable jet dynamics produce
enhanced synoptic lift along/ahead of approaching cold front. As
storms become parallel to upper flow, training appears likely
tonight along/south of a Danville to Jacksonville line. Latest NAM
continues to put down some hefty rainfall totals across this area.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 355 AM CDT MON SEP 1 2014
Shortwave trough axis approaching Illinois from the west this
morning bringing a line of thunderstorms to the region. Trends this
morning are for the line splitting into to intense lines...one
grazing Knox, Peoria, Stark county and likely Marshall and Woodford
as it continues this morning. Have reports of pea-sized hail and
wind gusts 30-40 mph with the more intense storm cells. The intense
activity looks like it will have a break through central IL in the
early morning once this initial activity shifts east-northeastward.
Isolated thunderstorms will likely develop throughout the CWA during
the morning...however daytime heating will likely be necessary to
bring CAPE values up to 1500-2500 J/KG range to bring a better
chance for severe storms when combined with 30-50 kt bulk shear
values also shifting into central Illinois. Large hail and severe
wind gusts will be a threat with the stronger storms this
afternoon...and have continued mention of severe hail and heavy rain
in forecast grids beginning at 3 pm this afternoon...continuing
through around midnight. Heavy rain will continue through the night
as a potent and moist low-level jet continues to push through the
CWA...along with lift associated with the progressive trough and
cold frontal boundary.
&&
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 355 AM CDT MON SEP 1 2014
00Z models have trended slower with frontal boundary pushing into
southeast IL Tue especially the NAM model and have increase pops to
likely se of I-70 Tue morning. NAM model may be overdoing qpf
amounts Tue morning over southeast IL but models have trended higher
with qpf amounts with precipitable water values of 1.5-2 inches
from 12-15Z Tue and have increased qpf amounts to around a quarter
inch in southeast IL. IL river valley should be dry Tue and chances
of showers and thunderstorms will diminish from nw to se during
Tue afternoon. Highs 82-88F Tue and still rather humid especially
in southeast IL with dewpoints 70-75F while dewpoints lower into
mid 60s over IL river valley. Dry conditions return across area
Tue night with frontal boundary dropping south of area. Lows in
the low to mid 60s Tue night.
Models show frontal boundary starting to lift back north especially
over MS river valley and MO on Wed and have kept 20-30% chance of
showers and thunderstorms sw areas by Wed afternoon with ne areas
staying dry Wed. Warm highs in the mid to upper 80s Wed and model
guidance has trended upward in high temps Wed. Dewpoints elevate
during day Wed into upper 60s and lower 70s Wed afternoon.
Convection chances appear highest over northern IL Wed night closer
to short waves tracking into WI/northern IL and eventually eastward
into lower MI and northern IN. Have areas south of I-72 dry Wed
night.
Thu and Fri still appear to be back into the heat and humidity with
highs in the upper 80s and lower 90s and dewpoints peaking in the
low to mid 70s giving afternoon heat indices of upper 90s to lower 100s
especially Thu afternoon and in southeast IL Friday afternoon. A 593
dm 500 mb high pressure ridge over the southeast states builds the
heat into central/southeast IL late this work week. Most of our area
should be dry Thu and Thu night with just slight chance of
convection Thu afternoon mainly over the Wabash river valley and
nw of IL river Thu night. Models have trended faster with cold
front dropping se through central IL Friday and thru southeast IL
Fri evening. Have increased pops Friday and also trending cooler
with temps and dewpoints during the weekend as 1025 mb high
pressure settles into the Great Lakes region.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1248 PM CDT MON SEP 1 2014
Convective development/evolution remains in question, as previous
outflow boundary has pushed east of the I-55 corridor early this
afternoon. Most model solutions are keeping central Illinois
largely dry through the afternoon, with thunderstorms
developing/increasing after dark across the south. Based on 12z
NAM and latest HRRR, it appears the axis of heavy rain will be
focused along the I-70 corridor between 05z and 12z. As such, have
kept both KPIA and KBMI dry through the entire 18z TAF period.
Further south, have introduced -RA with VCTS at the remaining
terminals after 05/06z, thinking they may be on the northern
fringe of the low-level jet enhanced precip area overnight.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1115 AM CDT MON SEP 1 2014
.DISCUSSION...
340 AM CDT
ENTERING SEPTEMBER AND METEOROLOGICAL AUTUMN WE STILL FIND THE
FORECAST CHALLENGES TO BE MORE SUMMER-LIKE...AT LEAST EARLY ON IN
THE FORECAST. THAT IS STORM AND HEAVY RAIN POTENTIAL TODAY AND
TONIGHT...THEN STORM CHANCES WEDNESDAY NIGHT AND FRIDAY WHICH
SANDWICH A POSSIBLE 90 PLUS DEGREE DAY ON THURSDAY. LESS BUT
STILL SOME TIME WAS SPENT ON THE FINAL CHALLENGE OF HOW MUCH OF A
COOL DOWN OCCURS THE FIRST FULL WEEKEND OF THIS NEW METEOROLOGICAL
SEASON.
SYNOPSIS...
A LONG WAVE TROUGH EXTENDING SOUTHWARD THROUGH CANADA INTO THE NORTH
CENTRAL U.S. HAS A VERY PROGRESSIVE SHORT WAVE FEATURE MOVING
THROUGH ITS SOUTHERN BASE. THIS IS SPEEDING EAST-NORTHEAST ACROSS
IA EARLY THIS MORNING. A SURFACE COLD FRONT MOVING EAST LAGS THIS
SHORT WAVE...EXTENDING FROM NORTHERN MN THROUGH THE TX PANHANDLE
EARLY THIS MORNING...WITH MULTIPLE SURFACE WAVES IN THE 1003MB
NEIGHBORHOOD ALONG IT. NORTHWEST SURFACE FLOW BEHIND THIS FRONT IS
NOT PARTICULARLY STRONG SO THIS FRONT WILL CONTINUE TO BE A SLOW-
MOVER TODAY...NOT EXPECTED TO ENTER THE FORECAST AREA UNTIL THIS
EVE. BEING WITHIN A WARM SECTOR UNDER QUICKENING UPPER/MID-LEVEL
FLOW PRESENTS THE STORM CHANCES THESE 24 HOURS.
THIS MORNING...
A LOOSELY DEFINED MCS MOVING EASTWARD INTO NORTHWEST IL EARLY THIS
MORNING WANED CONSIDERABLY WITH WARMING CLOUD TOPS AND OUTFLOW
EXTENDING WELL AHEAD OF IT. SEEING AN UPTICK ACROSS WEST CENTRAL IL
LIKELY ASSOCIATED WITH LIFT OF THE AFOREMENTIONED PROGRESSIVE SHORT
WAVE. HIGH RESOLUTION MODELS GREATLY VARY ON WHAT WILL HAPPEN EVEN
JUST A FEW HOURS OUT...BUT WOULD EXPECT SYNOPTICALLY TO SEE SOME
CONVECTION EVOLVE INTO THE FORECAST AREA THIS MORNING...POSSIBLY
ONLY THE WESTERN/SOUTHWESTERN AREA BUT STILL CANT RULE OUT SCATTERED
ACTIVITY MOVING EASTWARD THROUGH THE ENTIRE AREA INCLUDING
CHICAGO DURING MID/LATE MORNING. DESPITE A FAIRLY STRONG LOW-LEVEL
JET INTO ANY ACTIVITY...THE CONTINUED BROAD AREA OF STORMS ACROSS
EASTERN KS INTO WEST/SOUTHWEST MO THROUGH EARLY TO MID MORNING
SHOULD LESSEN MOISTURE TRANSPORT AND THUS ABILITY TO REALIZE STEEP
LAPSE RATES ALOFT FOR MORE ROBUST ACTIVITY...AND MAYBE EVEN
THUNDER IN GENERAL NORTH OF INTERSTATE 80.
THIS AFTERNOON AND TONIGHT...
DESPITE THIS BEING IN THE FIRST 12 HOURS OF THE FORECAST...DUE TO
INFLUENCE OF MORNING STORMS AND LARGE MODEL DIFFERENCES...CONFIDENCE
ON SPECIFICS IN THESE PERIODS REMAIN LOW. THERE SHOULD BE SOME
FORM OF OUTFLOW BOUNDARY OR BOUNDARIES FROM MORNING ACTIVITY/CLOUD
COVER THAT LINGER INTO THE FORECAST AREA INTO THE AFTERNOON...MOST
FAVORED SOUTH OF INTERSTATE 80. AS WARMING AND DESTABILIZATION
OCCURS WITH DEW POINTS AROUND 70F...COULD SEE SCATTERED ACTIVITY
DEVELOP NEAR ANY SUCH BOUNDARIES DURING THE MID TO LATE AFTERNOON.
THE SECOND UPPER WAVE ACROSS WESTERN WY THIS MORNING WILL BEGIN TO
APPROACH THE REGION AS WELL BY LATE IN THE DAY...WITH FORCING FROM
THIS POSSIBLY AIDING IN SCATTERED STORM DEVELOPMENT ACROSS MUCH OF
THE REGION. EVEN EARLY THIS MORNING THERE ARE A HANDFUL OF STORMS
ACROSS THE UPPER MIDWEST NOT LINKED TO ANY SPECIFIC SURFACE
FEATURE. INCREASING DEEP LAYER SHEAR OF 35 TO 50 KT WILL SUPPORT
ISOLATED TO SCATTERED SEVERE DISCRETE STORMS IN THE REGION.
WHILE IT REMAINS DIFFICULT TO PINPOINT TIMING...IT WOULD SEEM THE
GREATEST COVERAGE IN REDEVELOPING STORMS THIS EVENING WOULD BE IN
THE SOUTHERN FORECAST AREA WHERE AFOREMENTIONED BOUNDARY MAY OCCUR
AND MODEST SOUTHWEST 850-925MB FLOW AND MOISTURE TRANSPORT
REMAINS. AS THE AREA BECOMES UNDER A RIGHT ENTRANCE REGION TO THE
UPPER JET...DO EXPECT INCREASING ASCENT TONIGHT IN THE REGION FOR
MORE ROBUST CONVECTION AND POTENTIAL SEVERE AND HEAVY RAIN
THREATS. RIGHT NOW A GUIDANCE OVERLAP WOULD INDICATE THE FAR
SOUTHEAST FORECAST AREA IS MOST FAVORED FOR THIS. PRECIPITABLE
WATERS AROUND TWO INCHES AND STORM MOTIONS NEARLY PARALLEL TO THE
UPPER AND MID LEVEL FLOW WILL PRESENT HEAVY RAIN THREATS IN
THE GENERAL CENTRAL TO SOUTHERN IL INTO IN REGIONS...BUT AGAIN AT
THIS TIME CONFIDENCE VARIES ON PLACEMENT. BECAUSE OF THAT WILL
CONTINUE WITH THE HYDROLOGIC OUTLOOK /ESF/ FOR THE AREAS HIT HARD
ON SATURDAY NIGHT WITH HEAVY RAINFALL.
TUESDAY AND WEDNESDAY...
THE FRONT SHOULD CLEAR THE FORECAST AREA SOMETIME TUESDAY MORNING.
WHILE DRY AIR ADVECTION WILL OCCUR...LIMITED CONVERGENCE REMAINS
IN THE SOUTHEAST FORECAST AREA FOR POSSIBLY A STORM OR TWO TUESDAY
BUT IT LOOKS TO BE A LOW CHANCE. TEMPERATURES ONLY COOL SLIGHTLY
AS HIGH PRESSURE QUICKLY MOVES ATOP THE AREA TUESDAY NIGHT AND
THEN EASTWARD.
WEDNESDAY NIGHT THROUGH FRIDAY...
WARM AIR ADVECTION AND A RAPID PRECIPITABLE WATER INCREASE IS
FORECAST WEDNESDAY NIGHT ON ALL GUIDANCE. FEEL THAT MODELS MAY BE
UNDER-DOING THE STORM CHANCES GIVEN FORECAST PROFILES OF STEEPENING
LAPSE RATES WITHIN A RAPIDLY MOISTENING COLUMN...AT LEAST IN THE
WESTERN FORECAST AREA. SO HAVE INCREASED POPS IN THAT AREA. AS FOR
THURSDAY...HAVE GONE DRY IN MANY AREAS COLLABORATING AND
UNDERCUTTING A MODEL BLEND OF POPS. THE SYNOPTIC PATTERN FAVORS A
HOT DAY AND BARRING ANY STRATUS ISSUES WITH WEDNESDAY NIGHTS WARM
AIR ADVECTION AND POSSIBLE PRECIP...SHOULD SEE THE 90 DEGREE MARK
REACHED OR EXCEEDED ACROSS A GOOD PART OF THE FORECAST AREA BASED
ON STRONG SOUTHWEST FLOW AND FORECAST 850MB AND 925MB TEMPERATURES
COMPARED TO CLIMATOLOGY. FOR NOW HAVE KEPT THE NORTH A LITTLE
BELOW THAT WITH THE POSSIBILITY OF MORNING CLOUDS. THE SYSTEM
COLD FRONT IS PRESENTLY FORECAST BY THE EC AND THE GFS TO COME
THROUGH THE AREA SOMETIME ON FRIDAY WHICH WOULD BRING STORM
CHANCES WITH IT...AS WELL AS FLOW TURNING OFF THE LAKE BEHIND ITS
PASSAGE.
BEYOND...
NO CHANGES MADE TO THIS WEEKEND WHERE HIGHS LOOK TO BE AROUND 70
WITH DRY CONDITIONS BEHIND THE AFOREMENTIONED FRONT. HIGH PRESSURE
AROUND 1023MB IS FORECAST BY A BLEND OF GUIDANCE. GIVEN THE 925MB
TEMPERATURES FORECAST IF THAT HIGH IS CENTERED OVER THE FORECAST
AREA SOMETIME SUNDAY OR MONDAY NIGHTS /7TH OR 8TH/...LOWS IN
OUTLYING AREAS WOULD LIKELY BE IN THE 40S.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* MVFR CIGS/VSBYS IN THE SHORT TERM WITH SHRA.
* CEILING TRENDS THROUGH THE AFTERNOON...MVFR POSSIBLE.
* WINDS GRADUALLY VEERING MORE WESTERLY THEN NORTHWEST LATE.
* VCSH AGAIN THIS EVENING...ISOLATED TSRA NOT OUT OF THE QUESTION.
LENNING
//DISCUSSION...UPDATED 12Z...
CONVECTIVE CHANCES AND TIMING CONTINUE TO BE THE PRIMARY WEATHER
CONCERN AND FOCUS FOR THE AREA TODAY.
THE OVERNIGHT THUNDERSTORM ACTIVITY TO OUR WEST HAS DISSIPATED AS
IT MOVED ACROSS NORTHERN ILLINOIS. HOWEVER...ITS EFFECTS ON THE
SURFACE WINDS AND CIGS REMAIN. AS SUCH...IT APPEARS THAT A SHORT
PERIOD OF LOW MVFR CIGS AND AN EAST-SOUTHEASTERLY WIND COMPONENT
ARE EXPECTED THROUGH AROUND 14 UTC THIS MORNING BEFORE THE WINDS
REVERT BACK OUT OF THE SOUTHWEST AND BECOME A BIT GUSTY BY MID TO
LATE MORNING.
UNCERTAINTY REMAINS SOMEWHAT HIGH IN WHETHER OR NOT ANY CONVECTIVE
ACTIVITY WILL IMPACT THE TERMINALS TODAY. OVERALL IT APPEARS THE
BEST CHANCES IN THE NEAR TERM WILL BE ROUGHLY BETWEEN 16 AND 19
UTC AS A WEATHER DISTURBANCE ACROSS NORTHEASTERN MISSOURI SHIFTS
EASTWARD OVER THE AREA. THIS COULD LEAD TO SOME DEVELOPMENT
NEAR...OR JUST SOUTH OF THE TERMINALS DURING THIS PERIOD.
THEREAFTER...IT ALSO APPEARS THERE MAY BE ANOTHER CHANCE FOR SOME
SCT STORMS THIS EVENING AFTER 23 UTC AS ANOTHER STOUT UPPER LEVEL
DISTURBANCE MOVES OVER NORTHERN ILLINOIS AS A COLD FRONT
APPROACHES. TIMING AT THIS JUNCTURE REMAINS VERY DIFFICULT TO PIN
DOWN...AND THIS WILL NEED TO BE IRONED OUT AS WE GET A BETTER
HANDEL ON TRENDS THROUGH THE DAY. EITHER WAY...THERE WILL LIKELY
BE AREAS OF CONVECTIVE ACTIVITY THIS AFTERNOON AND TONIGHT SOUTH
OF THE TERMINALS.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM TO HIGH CONFIDENCE OF BRIEF MVFR CIGS/VSBYS IN THE SHORT
TERM WITH SHRA...THEN IMPROVING.
* MEDIUM TO HIGH CONFIDENCE IN WINDS...AND HIGH CONFIDENCE THEY
REMAIN FROM A WESTERLY COMPONENT.
* MEDIUM TO LOW CONFIDENCE OF SHRA AGAIN THIS EVENING...AND LOW
CONFIDENCE REGARDING ISOLATED TSRA.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH THURSDAY...PREDOMINANTLY VFR.
FRIDAY...CHANCE OF SHRA/TSRA.
SATURDAY AND SUNDAY...PREDOMINANTLY VFR.
KJB
&&
.MARINE...
232 AM CDT
IT LOOKS TO BE AN ACTIVE WEATHER DAY ACROSS THE LAKE...WITH STOUT
SOUTHERLY WINDS LAKE-WIDE...AND THE THREAT FOR SOME STRONG TO SEVERE
THUNDERSTORMS ACROSS SOUTHERN LAKE MICHIGAN. THESE STRONG SOUTHERLY
WINDS WILL RESULT IN WINDS AROUND 25 KT AND THE ONGOING SMALL CRAFT
ADVISORY STILL APPEARS GOOD. THE SURFACE LOW...RESPONSIBLE FOR THESE
STRONG SOUTHERLY WINDS TODAY...WILL SHIFT ACROSS ONTARIO...AND TO
NEAR JAMES BAY BY THIS EVENING WHILE DEEPENING TO AROUND 29.2
INCHES. AS THIS OCCURS...AN ASSOCIATED COLD FRONT WILL BE DRAWN
EASTWARD ACROSS THE LAKE BY EARLY TUESDAY MORNING. WINDS WILL BECOME
WESTERLY AND ABATE SIGNIFICANTLY WITH THE PASSAGE OF THIS FRONT.
ANOTHER PERIOD OF STRONGER SOUTHERLY WINDS LOOKS TO SET UP AGAIN
WEDNESDAY NIGHT AND THURSDAY AS ANOTHER POTENT AREA OF LOW PRESSURE
TRACKS EASTWARD ACROSS ONTARIO. WINDS SPEEDS COULD AGAIN BE AROUND
25 KT OUT OF THE SOUTH DURING THIS PERIOD. ANOTHER STRONGER COLD
FRONT LOOKS TO SHIFT DOWN THE LAKE IN THE WAKE OF THIS LOW LATE
FRIDAY AND THIS COULD SET THE STAGE FOR A DECENT NORTHERLY WIND
EVENT ACROSS THE LAKE AS A STOUT AREA OF HIGH PRESSURE QUICKLY
BUILDS EASTWARD ACROSS THE UPPER MIDWEST. STRONG NORTHERLY WINDS OF
25 TO 30 KT APPEAR QUITE POSSIBLE IN THE WAKE OF THIS COLD FRONT
FRIDAY NIGHT INTO SATURDAY...WHICH WOULD ALSO RESULT IN LARGE WAVES
IN EXCESS OF 5 FEET ACROSS SOUTHERN LAKE MICHIGAN INTO NEXT
WEEKEND.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM MONDAY.
&&
$$
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
NATIONAL WEATHER SERVICE LINCOLN IL
1001 AM CDT Mon Sep 1 2014
.UPDATE...
ISSUED AT 1001 AM CDT MON SEP 1 2014
Line of strong to severe thunderstorms tracked across Iowa last
night, then rapidly dissipated as it pushed toward the
Mississippi River early this morning. Outflow boundary from this
dying convection is currently approaching the I-55 corridor
as evidenced by westerly winds across all sites in the Illinois
River Valley. Think this outflow will eventually serve as the
primary focus for additional thunderstorm development later today.
Still some question as to exactly where the boundary will lay out
and when convection will fire, but the latest thinking from SPC
has pushed the best severe weather risk much further southeast,
generally along/south of a Danville to Jacksonville line. HRRR is
performing very poorly this morning and its solution has been
completely disregarded. Meanwhile, the 12z NAM seems to have at
least a reasonable handle on the situation, showing storms
developing by early afternoon near I-55, then shifting further
east and south later in the day. Will continue to monitor
stability parameters to see if projected 1500 to 2500J/kg CAPEs
can be realized. If the airmass destabilizes as predicted,
increasing shear values will help storms organize and potentially
produce large hail and damaging winds this afternoon into this
evening. Am still concerned about the threat for heavy rainfall
across the E/SE CWA tonight as favorable jet dynamics produce
enhanced synoptic lift along/ahead of approaching cold front. As
storms become parallel to upper flow, training appears likely
tonight along/south of a Danville to Jacksonville line. Latest NAM
continues to put down some hefty rainfall totals across this area.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 355 AM CDT MON SEP 1 2014
Shortwave trough axis approaching Illinois from the west this
morning bringing a line of thunderstorms to the region. Trends this
morning are for the line splitting into to intense lines...one
grazing Knox, Peoria, Stark county and likely Marshall and Woodford
as it continues this morning. Have reports of pea-sized hail and
wind gusts 30-40 mph with the more intense storm cells. The intense
activity looks like it will have a break through central IL in the
early morning once this initial activity shifts east-northeastward.
Isolated thunderstorms will likely develop throughout the CWA during
the morning...however daytime heating will likely be necessary to
bring CAPE values up to 1500-2500 J/KG range to bring a better
chance for severe storms when combined with 30-50 kt bulk shear
values also shifting into central Illinois. Large hail and severe
wind gusts will be a threat with the stronger storms this
afternoon...and have continued mention of severe hail and heavy rain
in forecast grids beginning at 3 pm this afternoon...continuing
through around midnight. Heavy rain will continue through the night
as a potent and moist low-level jet continues to push through the
CWA...along with lift associated with the progressive trough and
cold frontal boundary.
&&
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 355 AM CDT MON SEP 1 2014
00Z models have trended slower with frontal boundary pushing into
southeast IL Tue especially the NAM model and have increase pops to
likely se of I-70 Tue morning. NAM model may be overdoing qpf
amounts Tue morning over southeast IL but models have trended higher
with qpf amounts with precipitable water values of 1.5-2 inches
from 12-15Z Tue and have increased qpf amounts to around a quarter
inch in southeast IL. IL river valley should be dry Tue and chances
of showers and thunderstorms will diminish from nw to se during
Tue afternoon. Highs 82-88F Tue and still rather humid especially
in southeast IL with dewpoints 70-75F while dewpoints lower into
mid 60s over IL river valley. Dry conditions return across area
Tue night with frontal boundary dropping south of area. Lows in
the low to mid 60s Tue night.
Models show frontal boundary starting to lift back north especially
over MS river valley and MO on Wed and have kept 20-30% chance of
showers and thunderstorms sw areas by Wed afternoon with ne areas
staying dry Wed. Warm highs in the mid to upper 80s Wed and model
guidance has trended upward in high temps Wed. Dewpoints elevate
during day Wed into upper 60s and lower 70s Wed afternoon.
Convection chances appear highest over northern IL Wed night closer
to short waves tracking into WI/northern IL and eventually eastward
into lower MI and northern IN. Have areas south of I-72 dry Wed
night.
Thu and Fri still appear to be back into the heat and humidity with
highs in the upper 80s and lower 90s and dewpoints peaking in the
low to mid 70s giving afternoon heat indices of upper 90s to lower 100s
especially Thu afternoon and in southeast IL Friday afternoon. A 593
dm 500 mb high pressure ridge over the southeast states builds the
heat into central/southeast IL late this work week. Most of our area
should be dry Thu and Thu night with just slight chance of
convection Thu afternoon mainly over the Wabash river valley and
nw of IL river Thu night. Models have trended faster with cold
front dropping se through central IL Friday and thru southeast IL
Fri evening. Have increased pops Friday and also trending cooler
with temps and dewpoints during the weekend as 1025 mb high
pressure settles into the Great Lakes region.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 708 AM CDT MON SEP 1 2014
A mix of IFR and MVFR ceilings and southerly winds generally 8-12
kts this morning across central Illinois as a cold front
approaches from the west. A line of thunderstorm activity ahead of
the front continues to approach, however activity is generally weak
along portions of the line headed for central IL. As surface
heating takes place, thunderstorm development will intensify
through the early afternoon as daytime heating initiates and the
most intense portions of the storm system move into the region.
Some storms may become severe with hail and severe wind gusts this
afternoon and evening. Thunderstorm activity will shift toward
southeast portions of the state tonight. As no clear features
exist at this point to pinpoint timing of thunderstorms, have
broad-brushed thunderstorm activity with predominant -SHRA and VCTS
in TAFs starting 16Z- 17Z...then diminished VCTS/VCSH mention from
northwest to southeast overnight. Doubtful MVFR ceilings will
dissipate significantly through the day so have kept cigs no
better than bkn020-025 for the next 24 hours.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BARNES
SHORT TERM...ONTON
LONG TERM...07
AVIATION...ONTON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
319 PM CDT Mon Sep 1 2014
.SHORT TERM...(This Evening through Tuesday)
Issued at 319 PM CDT MON SEP 1 2014
Quick cyclonic upper flow remains in place with the core of last
night`s wave already in the Great Lakes and another weaker wave
coming into the High Plains per recent water vapor imagery. The cold
front`s location is hard to nail down behind outflow from the
overnight convection and weak pressure fields, but appears to be
bisecting the local area from southwest to northeast. Lower cloud
under a modest inversion has been rather prevalent today, keeping
temps in the 70s.
Modest convergence persists in east central Kansas this afternoon.
With still some CIN remaining per RAP analysis, confirmed by recent
visible satellite imagery, and the western upper wave staying well
north, storm chances don`t look great, but will maintain some
mention ahead of the front in east central Kansas, diminishing with
time as weak high pressure continues to move across northern sections
of the state. There are some breaks in the clouds to the south, and
some increase in instability is anticipated for the next few hours.
Deep layer is not very high in the weak low level wind fields, but
hard to completely rule out with mixed layer CAPE likely rising to
near 1500 J/kg. As the surface high builds in, winds should be
rather light, and depending on cloud trends particularly with
convection, a fairly good setup for radiational fog will be in place
with cloudy skies and limited mixing today and low cloud scouring
out following the recent heavy rain. Will go ahead with some patchy
fog mention at this point and let later shifts watch trends. Storm
chances continue to look like Tuesday but with the boundary again
possibly not far south, will keep a small chance near it. Better
mixing and insolation should yield highs back into the 80s.
.LONG TERM...(Tuesday Night through Monday)
Issued at 319 PM CDT MON SEP 1 2014
Models continue to show the potential for elevated thunderstorms
and large hail Tuesday night. The one wrinkle is the NAM appears to
be quite a bit stronger in magnitude for both the elevated
instability and effective shear. There is still good theta-e
advection along the nose of the low level jet as well as
isentropic upglide, so I think there should be some storms over
eastern KS. The question is whether they will be strong enough to
produce severe hail. Have continued with a chance POP through the
night and think the potential still exists for some severe storms.
It just may be more marginal than the NAM would suggest.
With the exception of some elevated precip possibly lingering
through the morning Wednesday, the forecast should quiet down as
the models keep the jet stream and synoptic scale energy north of
the forecast through Thursday morning. By Thursday night, a frontal
system is projected to begin moving into the area. There is some
uncertainty in the timing of the frontal system as most solutions
have trended faster with the front, the NAM being the fastest. For
now I`ve not made many changes from the previous forecast thinking
the front would move through mainly Friday and Friday evening with
the higher chances for precip in these periods. However if the
faster trend continues, the POPs may need to be pushed up in the
forecast as well. Have continued to trend POPs down for Saturday
and kept a dry forecast for Sunday with models showing surface
ridging and relatively dryer air over KS. By Monday, there is some
disagreement with the GFS and ECMWF in the amplification of an
upper trough across the west. Because the GFS is the more
amplified solution, it is quick to set up return flow with the
potential for shortwaves within southwesterly flow aloft to pass
near the area. Have taken a conservative approach with the
forecast at this time and have introduced only a slight chance for
precip on Monday until there is a little more agreement in
solutions.
Temps will remain quite warm Wednesday and Thursday as the models
show the thermal ridge over portions of the state. Because of this
have continued with highs in the 90s and lows from around 70 to
the mid 70s. Cold air advection is expected to increase Thursday
night as the front moves through the area. This should bring a
cool down for the weekend with highs in the 70s and lows in the
50s to around 60.
&&
.AVIATION...(For the 18Z TAFs through 18Z Tuesday Afternoon)
Issued at 1251 PM CDT MON SEP 1 2014
Appears convective concerns at TOP and FOE are somewhat lower than
earlier expectations with persistent cloud keeping instability in
check and area of convergence near passing boundary should be
south before instability develops. Flow behind the boundary should
clear skies somewhat allowing for decent radiational fog setup
around 11Z. Have introduced MVFR BR at this point.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...65
LONG TERM...Wolters
AVIATION...65
AREA FORECAST DISCUSSION
NWS JACKSON KY
155 PM EDT MON SEP 1 2014
.UPDATE...
ISSUED AT 155 PM EDT MON SEP 1 2014
UPDATED THE FORECAST TO BETTER TIME A LINE OF SCATTERED SHOWERS AND
THUNDERSTORMS MOVING IN FROM THE WEST. THIS LINE IS OUT AHEAD OF THE
COLD FRONT IN THE WARM AIR. THERE IS A BIT OF CURVATURE TO THE LINE
OF HEAVIEST STORMS;...SO WILL BE WATCHING FOR SOME POTENTIALLY STRONG
WIND GUSTS AS THE LINE GOES THROUGH. THE MERCER AND LINCOLN COUNTY
MESONET SITES SAW WIND GUSTS OF 30 MPH AS THE LINE WENT THROUGH.
CURRENT THINKING IS THE MAX GUSTS WILL STAY BELOW 40 MPH AND WILL BE
IN THE 20 TO 30 MPH RANGE AS THE STORMS MOVE INTO EASTERN KENTUCKY.
THE HEATING WILL BE A LITTLE BETTER...HOWEVER THE STORMS SEEM TO BE
WEAKENING A LITTLE BIT. SO FAR...HAVE ONLY BEEN SEEING UP TO ONE
QUARTER OF AN INCH OF RAIN FROM THE STORMS. HAVE A LITTLE CONCERN FOR
PARTS OF EASTERN KENTUCKY THAT GOT HAMMERED LAST NIGHT FROM THE HEAVY
RAIN...HOWEVER THESE STORMS HAVE BEEN QUITE PROGRESSIVE AND HAVE NOT
YET SEEN ANY TRAINING OF THE ECHOES.
UPDATE ISSUED AT 1048 AM EDT MON SEP 1 2014
UPDATED THE FORECAST TO INCLUDE ALL OF EASTERN KENTUCKY IN THE CHANCE
OF PRECIPITATION TODAY BASED ON THE HIGH HRRR AND RUC MODEL OUTPUT AS
WELL AS THE CURRENT RADAR. BASED ON THE NAM BUFFER SOUNDINGS...DO
HAVE SOME CONCERN THAT SOME OF THE STORMS TODAY COULD PRODUCE
STRONG...BUT SUB SEVERE...WIND GUSTS TODAY. THERE IS SUFFICIENT
INSTABILITY AND SOME DRY AIR ALOFT THAT WOULD MAKE THIS FAVORABLE.
STILL HAVE CONCERN FOR SOME STRONG STORMS FOR TUESDAY AFTERNOON AND
EVENING AS WELL. WOULD NOT BE TOO SURPRISED TO SEE EASTERN KENTUCKY IN
AN SPC SLIGHT RISK BOX FOR TOMORROW. THE REST OF THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 647 AM EDT MON SEP 1 2014
CLOUD COVER HAS EXPANDED A BIT FROM EARLIER...SO HAVE ADJUSTED THE
SKY COVER TO REFLECT CLOUDIER SKIES THROUGH DAYBREAK. ALSO ADJUSTED
TEMPERATURES UP A FEW DEGREES ACROSS THE BOARD AS THE CLOUDS ARE
HOLDING TEMPERATURES UP MAINLY IN THE LOW 70S. HRRR CONTINUES TO
PAINT OUT SOME ISOLATED TO SCATTERED SHOWERS AND STORMS THIS
AFTERNOON...AND THE 06Z NAM HAS ALSO NOW SUPPORTING A FEW SHOWERS AND
STORMS. THUS IT DOES LOOK LIKE SOME ACTIVITY CAN BE EXPECTED BY THE
AFTERNOON HOURS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 331 AM EDT MON SEP 1 2014
ZONAL FLOW RESIDES ACROSS KENTUCKY THIS MORNING...WITH A SHORTWAVE
TROUGH PUSHING ACROSS THE NORTHERN PLAINS. THE ZONAL FLOW FOR TODAY
WILL MEAN A QUIETER DAY. HOWEVER...A SUBTLE UPPER LEVEL WAVE WILL
PUSH ACROSS CENTRAL/NORTHEAST KENTUCKY THIS AFTERNOON AND EVENING.
WHILE OPERATIONAL GUIDANCE SUGGESTS VERY LITTLE IF ANY PRECIPITATION
TODAY...HI RES MODELS HAVE BEEN CONSISTENT ON SHOWING ISOLATED TO
SCATTERED CONVECTION DEVELOPING TODAY. THE MODEL GUIDANCE DOESN`T
SEEM TO MATCH UP TO WHAT THE HI RES MODELS ARE SHOWING. GIVEN THE
RECENT HISTORY OF HI RES MODELS DOING FAIRLY WELL WITH
CONVECTION...HAVE OPTED TO GO WITH ISOLATED TO SCATTERED SHOWERS AND
STORMS THIS AFTERNOON WITH THE HIGHEST CORRIDOR OF POPS FROM SOUTH
CENTRAL KENTUCKY...INTO NORTHERN AND NORTHEAST KENTUCKY.
HOWEVER...CANNOT RULE OUT A FEW ISOLATED SHOWERS OR STORMS DEVELOPING
ON THE HIGHER TERRAIN TO THE SOUTHEAST. WITH MODEST PRECIPITABLE
WATER VALUES AROUND 1.7 AND VERY HIGH FREEZING LEVELS (>15KFT)
POTENTIAL MAY EXISTS FOR SOME PERIODS OF VERY HEAVY RAIN.
FORTUNATELY...STORM MOVEMENT SHOULD BE SUFFICIENT TO LIMIT ANY
FLOODING CONCERNS TODAY.
THE SHOWERS/STORMS TODAY WILL BE TIED TO THE PEAK INSTABILITY HOURS
FROM MID AFTERNOON TO EARLY EVENING...BEFORE DYING OFF. THIS WILL
YIELD A QUITE NIGHT ACROSS THE AREA TODAY. CLEARING SKIES COULD YIELD
SOME PATCHY FOG...BUT WE MAY KEEP ENOUGH WIND AGAIN TO LIMIT IT TO
SOME DEGREE. THE SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL SEND
A WEAK COLD FRONT INTO THE OHIO RIVER VALLEY REGION. THIS WILL SPARK
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP ON
TUESDAY. THESE WILL TRACK SOUTHEAST ACROSS EASTERN KENTUCKY THROUGH
THE AFTERNOON AND EVENING HOURS. WITH MODEST 30-40KT BULK SHEAR
VALUES...THE POTENTIAL WILL EXISTS FOR SOME LINEAR STORM SEGMENTS
CAPABLE OF DAMAGING WINDS. PLAN TO CONTINUE TO HIGHLIGHT THIS
POTENTIAL IN THE HWO. THE FRONT WILL WASH OUT AND STALL OVER SOUTHERN
KENTUCKY BY THE EVENING HOURS WITH ACTIVITY DYING OUT WITH THE LOSS
OF DAYTIME HEATING.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 410 AM EDT MON SEP 1 2014
WARM WEATHER IS EXPECTED TO CONTINUE INTO THE EXTENDED PERIOD. THE
EXTENDED PERIOD OF THE FORECAST WILL BEGIN WITH THE TROUGH IN THE
NEAR TERM DEPARTING TO THE NORTH AND EAST...WITH A RATHER ZONAL
PATTERN TO START OVERALL. THE NEAR TERM COLD FRONT IS EXPECTED TO
BE DROPPING OR HAVE DROPPED ACROSS THE REGION AT THE START OF THE
PERIOD...FROM TUE NIGHT INTO EARLY ON WEDNESDAY AND BRING ISOLATED TO
SCATTERED CONVECTION. THE BOUNDARY SHOULD BECOME MORE ILL DEFINED AND
RATHER WASHED OUT ON WEDNESDAY AS IT REACHES THE TN VALLEY REGION.
WITH THE BOUNDARY IN THE AREA...CONVECTION WILL REMAIN POSSIBLE
MAINLY ACROSS THE SOUTH AND SOUTHEAST ON WEDNESDAY. MID AND UPPER
LEVEL RIDGING IS THEN EXPECTED TO BRIEFLY AMPLIFY ACROSS THE
SOUTHEASTERN AND MID ATLANTIC STATES THROUGH FRIDAY.
AS THE RIDGE BUILDS AND A SHORTWAVE TROUGH OR TWO IN THE ZONAL FLOW
MOVES FROM THE CENTRAL PLAINS TOWARD THE LOWER OH VALLEY REGION AND
INTO THE MIDDLE OH VALLEY REGION...WHAT IS LEFT OF THE BOUNDARY AND
DEEPER MOISTURE SHOULD ALSO BEGIN TO RETREAT BACK INTO THE REGION BY
WED NIGHT INTO THU. THIS SHOULD LEAD TO AN ADDITIONAL PERIOD WHERE
CONVECTION IS POSSIBLE. THE MODEL CONSENSUS IS FOR THE RIDGE TO
BUILD IN BEHIND THIS SHORTWAVE FOR THU NIGHT AND INTO EARLY ON FRI.
OVERALL...CONVECTION FROM THU NIGHT INTO FRIDAY MAY HAVE SOMEWHAT OF
A DIURNAL FLAVOR.
ALSO DURING THIS TIME...A SERIES OF TROUGHS WILL TRAVERSE THE
NORTHERN STREAM AND SEND A COLD FRONT SOUTH INTO AND GRADUALLY ACROSS
THE THE LOWER OH VALLEY REGION AND EASTERN KENTUCKY THIS WEEKEND.
THIS WILL BRING PERIOD OF UNSETTLED WEATHER...WITH PROLONGED CHANCES
FOR SHOWERS AND THUNDERSTORMS FROM SATURDAY INTO SUNDAY.
TEMPERATURES ARE EXPECTED TO AVERAGE NEAR TO A FEW DEGREES ABOVE
NORMAL FROM WED INTO SATURDAY FOR DAYTIME HIGHS...WITH OVERNIGHT LOW
HAVING THE GREATER DEPARTURE OF NEARLY 5 DEGREES ON AVERAGE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 155 PM EDT MON SEP 1 2014
A LINE OF SCATTERED SHOWERS AND THUNDERSTORMS ARE MOVING IN FROM THE
WEST. THIS LINE IS OUT AHEAD OF THE COLD FRONT IN THE WARM AIR. THERE
IS A BIT OF CURVATURE TO THE LINE OF HEAVIEST STORMS;...SO WILL BE
WATCHING FOR SOME POTENTIALLY STRONG WIND GUSTS AS THE LINE GOES
THROUGH. THE MERCER AND LINCOLN COUNTY MESONET SITES SAW WIND GUSTS
OF 30 MPH AS THE LINE WENT THROUGH. CURRENT THINKING IS THE MAX GUSTS
WILL STAY BELOW 40 MPH AND WILL BE IN THE 20 TO 30 MPH RANGE AS THE
STORMS MOVE INTO EASTERN KENTUCKY. THE HEATING WILL BE A LITTLE
BETTER...HOWEVER THE STORMS SEEM TO BE WEAKENING A LITTLE BIT. SOME
TEMPO IFR IS POSSIBLE WITH THE HEAVIEST STORMS. OTHERWISE VFR
CONDITIONS WILL PREVAIL UNTIL 6 TO 8Z WHEN SOME MVFR MIST MAY BE
EFFECTING THE TAF SITES. LOOKING FOR VSBY DOWN TO ABOUT 2 SM AT THE
TAF SITES BUT DOWN TO 1/2SM IN THE RIVER VALLEYS...ESPECIALLY IN
AREAS THAT GET RAIN TODAY. ONCE THE MIST CLEARS IN THE
MORNING...EXPECTING TO SEE SOME CONVECTION DEVELOP AGAIN TOMORROW.
THE CHANCE FOR STRONG THUNDERSTORMS IS GREATER FOR TOMORROW THAN IT
WAS TODAY. THE TIMING OF STORMS FOR TOMORROW IS TOO
UNCERTAIN...HOWEVER SHOULD BE AFTER 16Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...KAS
LONG TERM...JP
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1221 PM CDT Mon Sep 1 2014
.UPDATE...
Issued at 1221 PM CDT MON SEP 1 2014
Updated the AVIATION section.
UPDATE Issued at 849 AM CDT MON SEP 1 2014
Clearly evident yesterday`s and even some of last night`s models
were unable to resolve and capture several ongoing elements. PoPs
have been modified to capture ongoing convection over the east
that wasn`t model depicted prior. Also, winds were up quicker than
forecast this morning. 12z upper air data shows 30-40kt low level
jet already established. Thus, that leads us to the fact we are
already at Lake Wind Advisory criteria. Given it`s the holiday,
will go ahead with one. Gusty southwest winds expected 10 to 20
mph with 25+ mph winds possible at times. Not necessarily the
optimum trajectory, but quite breezy none the less. Meanwhile,
kept chance of convection going more aggressively than previously
forecast, given the amount of heating we will see ahead of the
decaying activity to our west. The HRRR shows some development in
this region of less cloud cover over the next several hours,
before dying off later in the afternoon. Will see if this actually
comes to fruition. For now, will keep PoPs in the chance category.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 200 AM CDT MON SEP 1 2014
MCS dropping down across MO will spread its clouds into/across PAH
FA this morning. It will also lay out some boundaries, the primary
one of which lays out across our northern tier this afternoon,
where we`ll have a slgt/small chance mentionable Pop.
As the mean energy in the long wave moves across the MS and Wabash
river valleys tonight and Tuesday, it will drag this primary
boundary into the heart of the FA and result in an uptick in Pops
to likely cat or better, particularly during the day Tuesday. This
has been a consistent model signal and looks a good bet with fropa
thru much of the area by 00Z Wed.
The front/boundary hangs up across our southern tier or just to
the south Tue night, and returns as a warm sector boundary late
Tue night and Wed. This is indicated by several model members so we
adjusted Pops accordingly.
Temps look to remain summerlike at or just above climo norms from
the mid/upr 80s to near 90 for highs, and generally in the
u60s/lower 70s for lows, with continued muggy dew points.
.LONG TERM...(Wednesday Night through Sunday)
Issued at 302 AM CDT MON SEP 1 2014
The PAH forecast area will be under the stabilizing influence
(aloft) of a broad mid level ridge late in the week, though some
models indicate that, with the substantial diurnal lower trop
instability present each day, some deep moist convection may be
strong enough to get past the warm mid level cap in some locations
during the daytime.
Meanwhile, a nrn stream longwave trof will be in the process of
lowering mid level heights across most of the CONUS. A sfc cold
front is forecast to sink sewd into the OH river valley by sometime
early Sat, with some timing differences among the med range models.
This feature will provide additional focus for lifting of abundant
moist air, thus PoPs are now 40-50 percent during the day Sat behind
the front. By Sunday, a drier air mass should be making its way into
our region, cutting off pcpn. However, the GFS and its ensemble
means suggested the center of the high (over the upper Midwest) may
be farther east than the ECMWF and its ensemble means indicated, and
therefore some warm advection showers/tstms may erupt just to our
west. We will have to wait and see how long the drying effects of
the dome of high sfc pressure actually last.
Warm and humid conditions will prevail late in the week ahead of the
front, with heat indices peaking around 100 Thu and Fri, but
especially Fri. For this forecast package, the frontal passage
should provide us end-of-the-weekend dewpoints in the 60s along with
&&
.AVIATION...
Issued at 1221 PM CDT MON SEP 1 2014
Prob of convection not high enough to include at the Terminals this
afternoon. Gusty SW winds will persist, 10-20kt +. Ocnl clouds aoa
12k/ft will continue, with sct-bkn025-035 expected, gradually
higher bases with time. Kept best chance of convection tonight,
within Prob30`s mainly aft 06z as convective chances increase
markedly after midnight. Winds will back to the south and fall to
aob 10 kts tonight.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...LAKE WIND ADVISORY until 6 PM CDT this evening FOR ILZ075>078-
080>094.
MO...LAKE WIND ADVISORY until 6 PM CDT this evening FOR MOZ076-086-
087-100-107>112-114.
IN...LAKE WIND ADVISORY until 6 PM CDT this evening FOR INZ081-082-
085>088.
KY...LAKE WIND ADVISORY until 6 PM CDT this evening FOR KYZ001>022.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
121 PM EDT Mon Sep 1 2014
...Updated Aviation Discussion...
...Forecast Update...
Issued at 1153 AM EDT Mon Sep 1 2014
A small cluster of showers with some embedded thunder is progressing
quickly across central Kentucky and will be capable of producing
some locally gusty winds into the 40-50 mph range as it moves into
the Green River Lake region and an area of maximized DCAPE and
surface instability. Have updated the forecast grids to reflect
this area of precipitation, along with the few other showers that
are scattered around the area.
Issued at 859 AM EDT Mon Sep 1 2014
Widely scattered showers have formed in a corridor of higher surface
dew points and CAPE, and diminished CIN, from Memphis to Detroit.
have upped PoPs for a few hours this morning in the northwest LMK
CWA to account for this.
.SHORT TERM (Now through Tuesday)...
Issued at 310 AM EDT Mon Sep 1 2014
A slow-moving cool front to our northwest will bring a noticeable
increase in southwesterly winds today, with gusts of 15 to 25 mph
likely this afternoon. First off though we may see some isolated
low-topped showers this morning, with convergence along a weak
low-level jet early this morning already initiating some in central
IN. HRRR indicates better coverage than what I`ll have in my
forecast, as current guidance coverage already is too high.
Cloud cover from the moist low levels and as additional moisture
streams into the region today in a deep southwesterly flow should
keep high temperatures from getting too far above normal, with
readings likely topping out in the mid to upper 80s. The focus for
storms this evening will be to our west and northwest, closer to the
approaching front. These storms may be able to get into our southern
Indiana counties around or after midnight.
There still are some uncertainties about how convective development
will occur from early to late Tuesday, as a lot will depend on the
evolution of these storms moving into our region. Should those
storms get in here more toward daybreak, then convective debris
could be enough to prevent furthern development during the day
Tuesday, despite relatively high precipitable waters. Should those
storms die off overnight and leave boundaries behind, Tuesday could
become more active with heating. Will leave in likely pops for the
day Tuesday, as would lean more towards the latter solution that
we`ll see a few breaks in the clouds to generate more storms.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Sep 01 2014
Tuesday Night and Wednesday...
Surface high pressure will slide over the Ohio Valley behind the
nearly washed out front to our south on Tuesday night. An isolated
shower or storm could linger into the evening hours across the south
or east CWA, otherwise expect a dry and slightly cooler night. Lows
should drop into the upper 60s and around 70. Isolated or widely
scattered diurnally driven showers/storms are expected to be
possible across southern KY on Wednesday. Most areas will stay dry
with mostly sunny skies and highs in the 85 to 88 degree range.
Wednesday Night - Friday...
The southern CONUS upper ridge will build over the area to end the
week, however this will not be enough to suppress diurnally
driven convection each afternoon and early evening. Will continue
mention of isolated to widely scattered coverage on Thursday, with
better coverage on Friday more solidly in the scattered range. Along
with this ridge, the heat and humidity will return with highs in the
upper 80s to around 90 each day. With dew points in the low 70s each
day, conditions will feel quite muggy. The environment should become
pretty unstable each afternoon/evening, however the lack of deep
layer flow will keep any convection pulse in nature. Lows by
Thursday night will be back in the low 70s.
Friday Night - Saturday Night...
The upper ridge will be suppressed southward to start the weekend, as
a wave skirts along the eastern US/Canada border. This will drag a
stronger cold front toward our moist and unstable airmass, keeping
scattered storms in play on Friday night. Saturday should bring the
best chance of storms for the whole forecast period as the front
tries to slide through. Have gone with 40-50% coverage. With
slightly better deep layer flow over the area, the threat for a few
stronger storms seems reasonable. Biggest concern would be gusty
winds, along with cloud to ground lightning and brief heavy
rainfall. A few storms could linger in our south and east Saturday
evening.
Expect more mild lows on Friday night with the mercury only dropping
to the low 70s. Highs on Saturday will be dependent on convection
and where the frontal boundary resides, but it looks like temps will
max out around 80 north, to the mid or upper 80s south. Lows
Saturday night will be cooler on the north side of the boundary.
Look for readings in the 60s.
Sunday...
Surface high pressure takes back over on Sunday, bringing dry and
cooler conditions to start the new work week. Look for highs in the
upper 70s and low 80s, with lows Sunday night expected to be in the
upper 50s and low 60s!
&&
.AVIATION (18Z TAF Update)...
Issued at 121 PM EDT Mon Sep 1 2014
Scattered showers and isolated thunderstorms will be possible this
afternoon in the warm, humid, unstable air over central Kentucky.
Any convection will be moving quickly and would affect any one
airfield only very briefly. For now will stick with VCSH, and
monitor radar closely for any helpful AMDs.
Winds this afternoon will be gusty from the southwest, gusting into
the 22 to 26 knot range.
Tonight winds will settle down though there will still be a
southerly breeze around 5 to 9 knots as we sit in accelerated flow
ahead of an approaching cold front. Isolated convection will be
possible, but at this time chances appear slight enough to omit from
the TAFs.
Toward morning that cold front will be entering the region, bringing
a band of showers and thunderstorms along with it. Right now will
time it into SDF around dawn and a little later at LEX/BWG, though
they could end up coming in a little quicker than that.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........13
Short Term.....RJS
Long Term......BJS
Aviation.......13
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
658 PM EDT MON SEP 1 2014
.AVIATION...
//DISCUSSION...
CONVECTION WILL BE ENDING AT THE BEGINNING OF THE FORECAST PERIOD
EVEN AS SURFACE TROUGH IS LAGGING WELL TO THE WEST. LIGHT SOUTHWEST
FLOW IN ADVANCE OF THIS FEATURE WILL MAINTAIN ABUNDANT LOW LEVEL
MOISTURE INTO TONIGHT WITH PATCHY/AREAS OF FOG AND STRATUS AGAIN
LATE TONIGHT INTO TUESDAY MORNING. DRIER AIR THEN MIXES INTO THE
AREA FROM MID/LATE MORNING TUESDAY ON INTO THE AFTERNOON WITH VFR
CONDITIONS EXPECTED WITH TIME.
FOR DTW...REMAINING SHRAS WITH PERHAPS A RUMBLE OF THUNDER WILL BE
MOVING EAST AND SOUTHEAST OF THE TERMINAL AS THIS FORECAST PERIOD
BEGINS. OTHERWISE...PATCHY FOG/STRATUS WILL BE POSSIBLE IN THE 07Z
TO 14Z TIME FRAME.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT THE TERMINAL THRU
01Z THIS EVENING.
* LOW CONFIDENCE IN CEILINGS BELOW 5000 FEET LATE TONIGHT INTO EARLY
TUESDAY.
&&
.PREV DISCUSSION...ISSUED 244 PM EDT MON SEP 1 2014
SHORT TERM...THIS EVENING AND TONIGHT
18Z SPECIAL CONFIRMS THE WARMER COLUMN DEPICTED BY THE RAP AND THEN
SOME. 900MB INVERSION IS QUITE A BIT MORE ROBUST THAN DEPICTED BY
THE GUIDANCE AS IS THE 600MB CAP. THUS, EVEN THE MOST TAME
DEPICTIONS OF CONVECTION IN THE NWP ARE LIKELY TOO AGGRESSIVE AND
CONCERNS REGARDING CAPPING NOTED IN THE MORNING UPDATE ARE
CONFIRMED. UPDRAFTS WILL STRUGGLE ACROSS MOST OF THE CWA WITH THE
EXCEPTION OF LOCATIONS NORTH OF I-69 AND ESPECIALLY WEST OF US-23
WHERE MID-LEVEL COOLING AND FORCING WILL BE MAXIMIZED. WITH THE LINE
ALREADY MARCHING TOWARD THIS AREA, EXPECT THAT THE ABUNDANCE OF
MID-LEVEL DRY AIR AND UNIDIRECTIONAL FLOW ABOVE 1.5KM WILL SUPPORT
BOWING SEGMENTS CARRYING A LOW-END SEVERE WIND THREAT. IN ADDITION,
ISOLATED TORNADO THREAT OUTLINED IN THE EARLIER UPDATE REMAINS IN
TACT. FOR REMAINING AREAS, EXPECT NOTHING MORE THAN A GUST TO 40
MPH. IN ADDITION, BACKED OFF ON POPS AS EARLIER SUSPICIONS REGARDING
COVERAGE POTENTIAL STILL LOOM.
A WEAK COLD FRONT WILL SAG THROUGH THE AREA TONIGHT. FRONTAL
INVERSION WILL PROMOTE EXPANSION OF STRATUS LATE TONIGHT, BUT EXPECT
THAT MOISTURE WILL BE TOO SHALLOW AND FORCING TOO WEAK TO SUPPORT
ANY LEGITIMATE COVERAGE OR INTENSITY OF SHOWERS. WITH UPPER SUPPORT
IN THE FORM OF A SHEARING SHORTWAVE NOT SCHEDULED TO ARRIVE UNTIL
TUESDAY MORNING PER 12Z GUIDANCE, AND MAINLY SOUTH OF THE AREA AT
THAT, NOTHING MORE THAN A CHC POP IS WARRANTED ATTM.
LONG TERM...TUESDAY THROUGH NEXT MONDAY
A COLD FRONT WILL BE SOUTHEAST OF THE CWA TO START OUT TUESDAY
MORNING. HOWEVER A MID LEVEL SHORTWAVE RIDING NORTHEAST ALONG THE
FRONT WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE
AREA TUESDAY MORNING. AFTER THE SHORTWAVE TRACKS OFF TO THE
NORTHEAST SIGNIFICANT DRYING WILL TAKE PLACE AS A SLUG OF 30 PERCENT
RELATIVE HUMIDITY AT 700 MB ADVECTS IN FROM THE WEST...ENDING RAIN
CHANCES QUICKLY EARLY TUESDAY AFTERNOON. WHILE THERE IS STILL SOME
UNCERTAINTY REGARDING HOW FAR WEST THE RAIN WILL FALL GIVEN THE PUSH
OF DRY AIR ADVECTING IN...THE LATEST SUITE OF MODELS HAS THE DRIER
AIR PUSHING IN A BIT SOONER THAN THE 00Z RUNS. THEREFORE WILL NUDGE
THE FORECAST A BIT DRIER TUESDAY AFTERNOON FROM THE PREVIOUS
FORECAST. DESPITE THE PASSAGE OF A COLD FRONT THERE ISN`T A LARGE
PUSH OF COLD AIR ASSOCIATED WITH IT...MEANING DAYTIME HIGHS ARE
EXPECTED TO GET AROUND 80 TUESDAY AFTERNOON BEHIND THE FRONT.
RIDGING WILL KEEP THE FORECAST DRY THROUGH WEDNESDAY AS REBOUNDING
HEIGHTS ALLOW DAYTIME HIGHS TO GET BACK INTO THE LOWER 80S BY
WEDNESDAY AFTERNOON.
MOISTURE SURGE FROM THE GULF OF MEXICO COMMENCES ON THURSDAY AS A
LOW CHANCE FOR CONVECTION EXISTS WITHIN THE WARM SECTOR OF A
REGION-WIDE LOW PRESSURE SYSTEM. BEST CHANCE FOR THUNDERSTORMS
/POSSIBLY SEVERE/ WILL BE FRIDAY AS WARM AND MOIST AIRMASS (85/70
T/TD) IS IN PLACE ALONG WITH FORECASTED CAPE OF 3000 J/KG. BULK
SHEAR INCREASES TO NEAR 30 KT IN THE 1-6 KM LAYER AS WELL. THESE
INGREDIENTS WILL BE IN PLACE AS A RAGGED COLD FRONT CROSSES THE
STATE. THIS BRINGS A TRIPLE THREAT OF SEVERE WEATHER WITH
WIND...HAIL...AND ISOLATED TORNADOES ALL POSSIBLE
MARINE...
SHOWERS AND THUNDERSTORMS WILL TRACK THROUGH THE CENTRAL GREAT LAKES
TONIGHT AS A COLD FRONT MOVES THROUGH LAKE HURON AND LOWER MICHIGAN.
SOME OF THESE STORMS MAY BE SEVERE...MAINLY ACROSS THE NORTHERN
PORTION OF LAKE HURON. HIGH PRESSURE WILL BUILD INTO THE REGION
BEHIND THIS FRONT ON TUESDAY...WHICH WILL REMAIN IN CONTROL OF THE
WEATHER THROUGH THURSDAY...PROVIDING FAVORABLE BOATING CONDITIONS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....99
SHORT TERM...JVC
LONG TERM....KURIMSKI/MM
MARINE.......KURIMSKI
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
244 PM EDT MON SEP 1 2014
.SHORT TERM...THIS EVENING AND TONIGHT
18Z SPECIAL CONFIRMS THE WARMER COLUMN DEPICTED BY THE RAP AND THEN
SOME. 900MB INVERSION IS QUITE A BIT MORE ROBUST THAN DEPICTED BY
THE GUIDANCE AS IS THE 600MB CAP. THUS, EVEN THE MOST TAME
DEPICTIONS OF CONVECTION IN THE NWP ARE LIKELY TOO AGGRESSIVE AND
CONCERNS REGARDING CAPPING NOTED IN THE MORNING UPDATE ARE
CONFIRMED. UPDRAFTS WILL STRUGGLE ACROSS MOST OF THE CWA WITH THE
EXCEPTION OF LOCATIONS NORTH OF I-69 AND ESPECIALLY WEST OF US-23
WHERE MID-LEVEL COOLING AND FORCING WILL BE MAXIMIZED. WITH THE LINE
ALREADY MARCHING TOWARD THIS AREA, EXPECT THAT THE ABUNDANCE OF
MID-LEVEL DRY AIR AND UNIDIRECTIONAL FLOW ABOVE 1.5KM WILL SUPPORT
BOWING SEGMENTS CARRYING A LOW-END SEVERE WIND THREAT. IN ADDITION,
ISOLATED TORNADO THREAT OUTLINED IN THE EARLIER UPDATE REMAINS IN
TACT. FOR REMAINING AREAS, EXPECT NOTHING MORE THAN A GUST TO 40
MPH. IN ADDITION, BACKED OFF ON POPS AS EARLIER SUSPICIONS REGARDING
COVERAGE POTENTIAL STILL LOOM.
A WEAK COLD FRONT WILL SAG THROUGH THE AREA TONIGHT. FRONTAL
INVERSION WILL PROMOTE EXPANSION OF STRATUS LATE TONIGHT, BUT EXPECT
THAT MOISTURE WILL BE TOO SHALLOW AND FORCING TOO WEAK TO SUPPORT
ANY LEGITIMATE COVERAGE OR INTENSITY OF SHOWERS. WITH UPPER SUPPORT
IN THE FORM OF A SHEARING SHORTWAVE NOT SCHEDULED TO ARRIVE UNTIL
TUESDAY MORNING PER 12Z GUIDANCE, AND MAINLY SOUTH OF THE AREA AT
THAT, NOTHING MORE THAN A CHC POP IS WARRANTED ATTM.
&&
.LONG TERM...TUESDAY THROUGH NEXT MONDAY
A COLD FRONT WILL BE SOUTHEAST OF THE CWA TO START OUT TUESDAY
MORNING. HOWEVER A MID LEVEL SHORTWAVE RIDING NORTHEAST ALONG THE
FRONT WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE
AREA TUESDAY MORNING. AFTER THE SHORTWAVE TRACKS OFF TO THE
NORTHEAST SIGNIFICANT DRYING WILL TAKE PLACE AS A SLUG OF 30 PERCENT
RELATIVE HUMIDITY AT 700 MB ADVECTS IN FROM THE WEST...ENDING RAIN
CHANCES QUICKLY EARLY TUESDAY AFTERNOON. WHILE THERE IS STILL SOME
UNCERTAINTY REGARDING HOW FAR WEST THE RAIN WILL FALL GIVEN THE PUSH
OF DRY AIR ADVECTING IN...THE LATEST SUITE OF MODELS HAS THE DRIER
AIR PUSHING IN A BIT SOONER THAN THE 00Z RUNS. THEREFORE WILL NUDGE
THE FORECAST A BIT DRIER TUESDAY AFTERNOON FROM THE PREVIOUS
FORECAST. DESPITE THE PASSAGE OF A COLD FRONT THERE ISN`T A LARGE
PUSH OF COLD AIR ASSOCIATED WITH IT...MEANING DAYTIME HIGHS ARE
EXPECTED TO GET AROUND 80 TUESDAY AFTERNOON BEHIND THE FRONT.
RIDGING WILL KEEP THE FORECAST DRY THROUGH WEDNESDAY AS REBOUNDING
HEIGHTS ALLOW DAYTIME HIGHS TO GET BACK INTO THE LOWER 80S BY
WEDNESDAY AFTERNOON.
MOISTURE SURGE FROM THE GULF OF MEXICO COMMENCES ON THURSDAY AS A
LOW CHANCE FOR CONVECTION EXISTS WITHIN THE WARM SECTOR OF A
REGION-WIDE LOW PRESSURE SYSTEM. BEST CHANCE FOR THUNDERSTORMS
/POSSIBLY SEVERE/ WILL BE FRIDAY AS WARM AND MOIST AIRMASS (85/70
T/TD) IS IN PLACE ALONG WITH FORECASTED CAPE OF 3000 J/KG. BULK
SHEAR INCREASES TO NEAR 30 KT IN THE 1-6 KM LAYER AS WELL. THESE
INGREDIENTS WILL BE IN PLACE AS A RAGGED COLD FRONT CROSSES THE
STATE. THIS BRINGS A TRIPLE THREAT OF SEVERE WEATHER WITH
WIND...HAIL...AND ISOLATED TORNADOES ALL POSSIBLE
&&
.MARINE...
SHOWERS AND THUNDERSTORMS WILL TRACK THROUGH THE CENTRAL GREAT LAKES
TONIGHT AS A COLD FRONT MOVES THROUGH LAKE HURON AND LOWER MICHIGAN.
SOME OF THESE STORMS MAY BE SEVERE...MAINLY ACROSS THE NORTHERN
PORTION OF LAKE HURON. HIGH PRESSURE WILL BUILD INTO THE REGION
BEHIND THIS FRONT ON TUESDAY...WHICH WILL REMAIN IN CONTROL OF THE
WEATHER THROUGH THURSDAY...PROVIDING FAVORABLE BOATING CONDITIONS.
&&
.AVIATION...ISSUED 114 PM EDT MON SEP 1 2014
//DISCUSSION...
LOW STRATUS CONTINUES TO MIX UP TO LOW VFR DIURNALLY FORCED CU.
EXPECT THIS TREND TO CONTINUE THROUGH THE NEAR TERM. ATTENTION
THEN TURNS TOWARD TSTORM CHANCES THIS AFTERNOON. CAPPING WILL
LIMIT POTENTIAL SOUTH OF KPTK SO TSHRA WAS REMOVED FOR THESE
LOCATIONS AS THE PROBABILITY IS NOW TOO LOW TO WARRANT A MENTION
IN THE TAFS. EXPECTATIONS REMAIN UNCHANGED FROM KFNT NORTH
UPSTREAM ACTIVITY IS MORE CERTAIN TO MOVE IN THIS AFTERNOON. LOW CLOUDS AND
PERHAPS A VISIBILITY RESTRICTION WILL BE POSSIBLE BEHIND THE FRONT
LATE TONIGHT BUT ONCE AGAIN EXPECT PRECIP POTENTIAL TO REMAIN
RATHER LOW WITH THE BULK OF 12Z GUIDANCE HOLDING ACTIVITY SOUTH OF
THE MICHIGAN BORDER.
FOR DTW...ALTHOUGH CONFIDENCE IN TSTORMS HAS DECREASED...IT AT LEAST
REMAINS PLAUSIBLE. THE BEST TIME FOR A THUNDERSTORM TO IMPACT THE
AIRPORT WILL BE 21Z-23Z THIS AFTERNOON. CONFIDENCE IN SHOWER
COVERAGE TOWARD MORNING IS ALSO QUITE LOW. ELECTED TO ELIMINATE
SPECIFIC MENTION FROM THE TAF UNTIL POTENTIALLY IMPACTED AREA BECOMES
MORE CLEAR.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILINGS BELOW 5KFT THIS AFTERNOON AND LATE TONIGHT
* LOW CONFIDENCE THAT A TSTORM WILL IMPACT KDTW
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...JVC
LONG TERM....KURIMSKI/MM
MARINE.......KURIMSKI
AVIATION.....JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
127 PM EDT MON SEP 1 2014
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 330 AM EDT MON SEP 1 2014
A COLD FRONT WILL MOVE INTO THE GREAT LAKES REGION FROM THE WEST
LATER TODAY AND INTO TONIGHT. SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO DEVELOP OVER SOUTHWEST LOWER MICHIGAN FROM THE LATE MORNING HOURS
PERSISTING INTO THE EVENING. SOME OF THE STORMS FROM THE MIDDAY
HOURS THROUGH THE EVENING MAY BE SEVERE WITH LARGE HAIL AND STRONG
WINDS. SHOWERS AND STORMS WILL GRADUALLY TAPER OFF TONIGHT
FROM NORTH TO SOUTH AS THE FRONT DROPS SOUTHWARD INTO INDIANA. DRY
WEATHER IS THEN EXPECTED FOR THE MOST PART FROM TUESDAY THROUGH
WEDNESDAY. CHANCES FOR SHOWERS AND STORMS INCREASE ONCE AGAIN
WEDNESDAY NIGHT THROUGH FRIDAY AS A LOW PRESSURE SYSTEM TRAVERSES
THE AREA. TEMPERATURES THIS WEEK WILL BE NEAR TO ABOVE NORMAL WITH
HIGHS IN THE UPPER 70S TO 80S ALL WEEK. A COOL DOWN IS EXPECTED NEXT
WEEKEND BEHIND A COLD FRONT THAT MOVES THROUGH ON FRIDAY.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 1100 AM EDT MON SEP 1 2014
ISOLATED SEVERE WEATHER THREAT CONTINUES THIS AFTERNOON (2PM - 8PM)
EAST OF U.S. 131 WITH DAMAGING WIND GUSTS THE MAIN THREAT. BRIEF
LOCALIZED FLOODING TYPICAL OF STRONG THUNDERSTORMS IS ALSO POSSIBLE.
APPROACHING WEAK FRONTAL BOUNDARY...SEPARATING DEWPOINTS IN THE LOW
70S FROM THOSE IN THE MID 60S...IS CURRENTLY ORIENTED NORTH-SOUTH
ACROSS EASTERN WISCONSIN AND ILLINOIS. THERE IS ALSO CONSIDERABLE
CLOUDINESS ALONG AND AHEAD OF FRONT WHICH IS TEMPERATURES AND
DESTABILIZATION OFTHE AIRMASS.
THE FRONT WILL SWEEP EASTWARD ACROSS THE CWA THIS AFTERNOON AND
EARLY EVENING PROVIDING LOW LEVEL LIFT AND POTENTIAL FOCUS FOR
DEVELOPMENT OF NEW STORMS. ALOFT HOWEVER...THE LEAD SHORTWAVE AND
NOSE OF UPPER JET WILL PUSH EASTWARD OVER THE REGION WITH BEST DEEP
LIFT NORTH MAINLY NORTH OF THE AREA.
INSTABILITY AND WIND FIELDS ARE FAVORABLE FOR SEVERE STORMS WITH
CAPE VALUES OF 500 - 1500 J/KG...0-6 KM BULK SHEAR VALUES NEAR 40
KTS...AND 0-1KM SHEAR VALUES AROUND 20 KTS. HOWEVER...LACK OF DEEP
LIFT WILL LIMIT COVERAGE OF STORMS AND OVERALL SEVERE THEAT
SIGNICANTLY. THIS SOLUTION IS REFLECTED IN MANY OF THE HIGHER
RESOLUTION CONVECTION ALLOWING MODELS INCLUDING LAST FEW NSSL WRF
AND HRRR RUNS.
OTHERWISE...THE SHORT TERM IS RELATIVELY QUIET. ANY STORMS THIS
EVENING SHOULD WORK SOUTH OF THE AREA OVERNIGHT. NOT OUT OF THE
REALM OF POSSIBILITIES FOR A FEW SHOWERS ON TUESDAY...BUT FELT THE
THREAT WAS SMALL ENOUGH TO GO DRY. TUESDAY NIGHT AND WEDNESDAY
SHOULD BE DRY WITH RIDGING IN PLACE AT THE SURFACE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON SEP 1 2014
THE MOST UNSETTLED WEATHER IN THE LONG TERM LOOKS TO OCCUR IN THE
FIRST COUPLE OF DAYS...FROM THE BEGINNING OF THE PERIOD WED NIGHT
INTO FRI NIGHT. THE LATEST TREND IS FOR A LITTLE MORE POSSIBLE PCPN
WED NIGHT INTO THU WITH THE PASSAGE OF THE WARM FRONT THROUGH THE
AREA. THIS LOOKS TO BE THE CASE DUE TO THE GRADIENT/LOW LEVEL JET
EXPECTED TO BE A LITTLE STRONGER WITH A STRONGER TROUGH MOVING IN.
HOW QUICKLY THE FRONT MOVES THROUGH WILL DICTATE HOW WARM WE GET ON
THU. IF THE FRONT MOVES QUICK ENOUGH...WE COULD HAVE A CHC TO WARM
TOWARD 90 WITH H850 TEMPS OF 20C ADVECTING IN. FOR NOW...WE HAVE
SETTLED WITH THE MID-UPPER 80S WITH THE UNCERTAINTY OF THE PCPN.
WE WILL SEE ANOTHER BATCH OF CONVECTION BE POSSIBLE THEN CENTERED
AROUND FRI AS THE COLD FRONT PUSHES THROUGH AND ENCOUNTERING THE
VERY WARM AND MOIST AIR MASS. WE COULD HAVE SOME ASSISTANCE VIA THE
RRQ OF AN UPPER JET TO OUR N/NE THAT WOULD SUPPLEMENT THE COLD
FRONTAL PASSAGE.
THE REMAINDER OF THE LONG TERM FROM SAT THROUGH SUN LOOKS TO BE
RATHER QUIET...YET COOL. WE WILL SEE A CANADIAN AIR MASS FILTER IN
BEHIND THE THU/FRI SYSTEM WITH A DECENT NNE LOW LEVEL FLOW USHERING
IT IN. THE UPPER FLOW WILL BE FROM THE NW AND A BIT OF A TROUGH WILL
BE OVER THE AREA. THE FAR ERN FLANK OF A SFC RIDGE WILL BE
BUILDING IN AS THE SYNOPTIC PATTERN OVER THE COUNTRY WILL FEATURE A
FAIRLY BROAD/EXPANSIVE UPPER RIDGE FROM THE ERN PACIFIC INTO THE
ROCKIES. THIS SHOULD KEEP THE AREA DRY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 122 PM EDT MON SEP 1 2014
A LINE OF SHOWERS AND THUNDERSTORMS WILL CROSS LOWER MICHIGAN THIS
AFTERNOON. BRIEF PERIODS OF HEAVY RAINFALL IS POSSIBLE WITH VSBYS
FALLING TO IFR/MVFR CONDITIONS. THE ACTUAL COLD FRONT WON/T PASS
THROUGH UNTIL AFTER MIDNIGHT. AS A RESULT...WE KEPT MVFR CIGS IN
THE TAFS UNTIL AROUND MIDNIGHT.
&&
.MARINE...
ISSUED AT 1100 AM EDT MON SEP 1 2014
SCA/BEACH HAZARD WORKING WELL WITHWIND GUSTS NEAR 30 KTS AND WAVE
AROUND 4 FT OBSERVED NORTH OF HOLLAND TOWARDS LUDINGTON AT THIS
TIME. WINDS WILL CONTINUE NEXT SEVERAL HOURS WITH WAVES UP TO 5
FEET. WINDS / WAVES WILL SUBSIDE QUICKLY LATE THIS AFTERNOON WITH
PASSAGE OF FRONT AND SHIFT OF WINDS TO A MORE WESTERLY DIRECTION.
THE NEXT POSSIBLE SET OF HEADLINES THAT MAY BE NEEDED FOR THE
NEARSHORE WATERS LOOKS TO START IN THE WED NIGHT/THU TIME FRAME AS
THE FLOW STRENGTHENS WITH A SURGE OF WARMER AIR WITH THE NEXT
FRONTAL SYSTEM POISED TO MOVE IN.
&&
.HYDROLOGY...
ISSUED AT 1237 PM EDT MON SEP 1 2014
RIVERS ARE RUNNING A LITTLE ABOVE NORMAL... BUT ARE STILL FAR BELOW
BANK FULL. PRECIPITATION THROUGH THIS EVENING IS EXPECTED TO TOTAL
AROUND A QUARTER OF AN INCH WITH ISOLATED LOCATIONS NORTHWEST OF
GRAND RAPIDS RECEIVING NEARLY AN INCH. THIS SHOULD LEAD TO SMALL
RISES ON AREA RIVERS WITH PEAK LEVELS BELOW BANK FULL BY MID WEEK.
ADDITIONAL PRECIPITATION IS POSSIBLE WEDNESDAY INTO FRIDAY NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 10 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
SYNOPSIS...DUKE
SHORT TERM...COBB
LONG TERM...NJJ
AVIATION...93
HYDROLOGY...63
MARINE...COBB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
123 PM EDT MON SEP 1 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT MON SEP 1 2014
WV IMAGERY AND RUC INDICATED A BROAD MID/UPPER LEVEL TROUGH FROM THE
ROCKIES INTO THE NRN/CNTRL PLAINS. AT THE SFC...A COLD FRONT
EXTENDED FROM NEAR INL THROUGH CNTRL MN INTO NW IA. A WEAK SHRTWV
FROM NE MN INTO NW WI SUPPORTED AN AREA OF SHOWERS AND ISOLD TSRA
OVER ERN MN INTO NW WI AND LAKE SUPERIOR. A STRONGER SHRTWV WAS
LOCATED OVER SW MN INTO NW IA. WITH ONLY MODEST 500-1000 J/KG
MUCAPE...ONLY A FEW TSRA WERE NOTED OVER THE REGION. THE MORE ACTIVE
CONVECTION OVER ERN LAKE SUPERIOR WAS ASSOCIATED WITH AN AREA OF
STRONGER 850 THETA-E ADVECTION AT THE NOSE OF THE LLJ.
TODAY...AS THE NW IA SHRTWV LIFTS TOWARD THE AREA WITH MODERATE
700-300 MB QVECTOR CONV AND THE COLD FRONT APPROACHES THE
AREA...EXPECT SHRA/TSRA COVERAGE TO INCREASE THIS MORNING. EVEN WITH
0-1KM/0-6KM SHEAR AROUND 40 KNOTS...SINCE INSTABILITY WILL REMAIN
LIMITED...MAINLY JUST BRIEF HEAVY RAIN IS EXPECTED. OVERALL RAINFALL
AMOUNTS SHOULD BE LIMITED GIVEN THE QUICK MOVEMENT OF THE CONVECTIVE
CELLS AND LACK OF LARGE SCALE ORGANIZATION. THE PCPN WILL DIMINISH
FROM WEST TO EAST THIS AFTERNOON AS THE COLD FRONT MOVES THROUGH AND
QVECTOR DIV SPREADS INTO UPPER MI IN THE WAKE OF THE SHRTWV. CLOUD
COVER WILL KEEP HIGH TEMPS NEAR OR SLIGHTLY BELOW SEASONAL AVERAGES
IN THE UPPER 60S TO AROUND 70.
TONIGHT...ANY LINGERING PCPN OVER THE ERN CWA IN THE EVENING WILL
END EARLY. OTHERWISE...A DRIER AIRMASS MOVING INTO THE AREA WITH
DEWPOINTS DROPPING TOWARD THE LOWER 50S WILL ALLOW TEMPS TO ALSO
DROP INTO THE LOWER TO MID 50S AS SKIES PARTIALLY CLEAR. AN INCREASE
IN CLOUD COVER IS EXPECTED LATE OVER THE SW CWA AHEAD OF THE NEXT
WEAK SHRTWV.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 321 AM EDT MON SEP 1 2014
IN THE WAKE OF STRONGER SHORTWAVE AND SFC FRONT MOVING THROUGH
TODAY...ANOTHER SHORTWAVE CLIPS ACROSS THE AREA ON TUESDAY IN
INCREASINGLY ZONAL FLOW ALOFT. MOISTURE IS LIMITED WITH THE WAVE AS
SOUNDINGS ONLY SHOW MOISTURE H8-H7. PRETTY HIGH BASED SHRA AND WILL
ALSO MENTION ISOLD TSRA WITH MLCAPE 500-1000 J/KG PER ECMWF AND GFS.
WILL INCLUDE SLIGHT CHANCE POPS. A LULL FOR TUE NIGHT AS SFC RIDGE
MOVES FROM MIDDLE MISSISSIPPI RIVER VALLEY TO THE OHIO VALLEY. LGT
SW WINDS ON PERIFERY OF THE RIDGE WILL LIMIT COOLING. LOWEST PWAT
FAR EAST CWA WHERE MIN TEMPS MAY FALL TO AROUND 50 DEGREES. ON
WEDNESDAY...GFS AND GEM-NH INDICATE SOME SHOWERS COULD OCCUR IN THE
AFTN OVER MAINLY THE WEST HALF CWA. WEAK SHORTWAVE IS THERE BUT ONLY
APPEARS THAT BEST MOISTURE INFLOW IS OVER FAR WEST CWA. WARM AIR
ADVECTION BOOSTS H85 TEMPS TO AROUND +15C SO AS LONG AS SKIES STAY
AT LEAST PARTLY CLOUDY...MAX TEMPS WILL TOP OUT IN THE MID 70S TO
LOWER 80S.
LATER WEDNESDAY NIGHT INTO THURSDAY MORNING LARGER SCALE LIFT
AHEAD OF UPPER TROUGH INCREASES OVER NORTHERN PLAINS AND WESTERN
GREAT LAKES. LIKELY WILL BE SOME SHORTWAVES SLIDING OUT OF NORTHERN
PLAINS AS WELL...THOUGH RIGHT NOW SIGNAL OF ANY STRONGER SHORTWAVE
IS MINIMAL. THERE IS A MID LEVEL JET MAX SLIDING OVER THE AREA AND
H85-H5 Q-VECTOR CONVERGENCE WILL BE ON THE INCREASE. PRIMARY SFC
TROUGH WILL BE OVER MINNESOTA AND BASED ON SFC WINDS AND
DWPNTS...THERE WILL BE A WARM FRONT VCNTY OF SOUTHERN/CENTRAL
MINNESOTA INTO WESTERN WISCONSIN. BULGE OF WARMTH ALOFT RESULTS IN
AN ELEVATED MIXED LAYER WITH H7-H5 LAPSE RATES OVER 8C/KM MAKING IT
OVER UPR LAKES AHEAD OF THE SFC TROUGH. RESERVOIR OF ML MUCAPE OVER
2000J/KG WILL BE JUST SOUTHWEST OF UPR MICHIGAN WITH MID LEVEL FLOW
SW-NE. EDGE OF SFC BASED CAPE AND ORIENTATION OF H85-H3 THICKNESSES
INDICATE THAT STRONGER STORMS MAY BE MORE TO SOUTHWEST OF UPR
MICHIGAN LATER WEDNESDAY NIGHT INTO THURSDAY MORNING. TOUGH TO SAY
AT THIS POINT THOUGH. CONSENSUS CHANCE POPS WORK FOR NOW SINCE THERE
WILL BE LARGE SCALE WARM AIR ADVECTION AND H85-H7 MOISTURE TRANSPORT
AIMED INTO THE AREA. MORE SHRA/TSRA POSSIBLE AS SFC FRONT WORKS
ACROSS UPR MICHIGAN LATER ON THURSDAY. PLENTY OF INSTABILITY AS
TEMPS IN THE SOUTH-SOUTHWEST FLOW AHEAD OF FRONT SHOULD REACH TOWARD
80 DEGREES WITH EVEN A FEW HOURS OF PARTIAL CLEARING SINCE H85 TEMPS
ARE 18-20C. MOISTURE AVAILABILITY/MID LEVEL CAPPING ALONG THE FRONT
REMAINS A CONCERN FOR COVERAGE OF SFC BASED STORMS IN THE AFTN. MODELS
MAY BE PICKING UP ON THIS AS GFS/ECMWF SHOW A MIN IN QPF 18Z-24Z BUT
THEN INCREASE IT BY 06Z ON FRIDAY AS FRONT WILL MAINLY BE SOUTH AND
EAST OF CWA BY THAT TIME. NO NEED TO GET TOO FANCY WITH THE GRIDS
ATTM GIVEN ALL THE UNCERTAINTY. KEPT WITH THE CONSENSUS CHANCE POPS
ON THURSDAY WITH THIS DROPPING OFF TO LOWER CHANCES THURSDAY NIGHT
CLOSER TO THE DEPARTING FRONT.
REST OF THE FORECAST LOOKS DRY AND COOLER AS HIGH PRESSURE BUILDS IN
ON FRIDAY AND WILL HOLD ON THROUGH NEXT WEEKEND. MAX TEMPS IN THE
MID 60S TO LOWER 70S. CHILLY LOWS POSSIBLE INLAND BOTH FRIDAY NIGHT
AND SATURDAY NIGHT DUE TO THE DRY AIRMASS AND LGT WINDS BENEATH THE
HIGH PRESSURE. BIAS CORRECTED GUIDANCES SHOWED MINS IN THE LOWER 40S
BUT WOULD NOT BE SURPRISED TO SEE READINGS DIPPING INTO THE 30S
EITHER OF THOSE NIGHTS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 122 PM EDT MON SEP 1 2014
IWD...MVFR CONDITIONS WILL PREDOMINATE EARLY BEFORE DRIER AIR MOVES
IN AND ALLOWS FOR CONDITIONS TO IMPROVE TO VFR BY THIS EVENING.
CMX...CONTINUED -SHRA EARLY SHOULD RESULT IN A PERIOD OF IFR
CONDITIONS DURING THE EARLY AFTERNOON BEFORE THE W WIND TAPS DRIER
AIR AND RESULTS IN IMPROVEMENT TO VFR THIS EVENING.
SAW...SOME SHRA WITH MVFR CONDITIONS WILL CONTINUE WITH THE APPROACH
OF A SFC COLD FRONT MOVING THROUGH EARLY THIS PERIOD. EXPECT
IMPROVEMENT LATE IN THE AFTERNOON WITH A WSHFT TO A DOWNSLOPE W
DIRECTION AND THE ARRIVAL OF DRIER AIR FOLLOWING THE FROPA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT MON SEP 1 2014
WINDS WILL BE 20 KNOTS OR LESS THROUGH THIS FORECAST PERIOD WITH
AREAS OF FOG PERSISTING UNTIL DRIER AIR MOVES INTO THE REGION
TONIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
114 PM EDT MON SEP 1 2014
.AVIATION...
//DISCUSSION...
LOW STRATUS CONTINUES TO MIX UP TO LOW VFR DIURNALLY FORCED CU.
EXPECT THIS TREND TO CONTINUE THROUGH THE NEAR TERM. ATTENTION
THEN TURNS TOWARD TSTORM CHANCES THIS AFTERNOON. CAPPING WILL
LIMIT POTENTIAL SOUTH OF KPTK SO TSHRA WAS REMOVED FOR THESE
LOCATIONS AS THE PROBABILITY IS NOW TOO LOW TO WARRANT A MENTION
IN THE TAFS. EXPECTATIONS REMAIN UNCHANGED FROM KFNT NORTH
UPSTREAM ACTIVITY IS MORE CERTAIN TO MOVE IN THIS AFTERNOON. LOW CLOUDS AND
PERHAPS A VISIBILITY RESTRICTION WILL BE POSSIBLE BEHIND THE FRONT
LATE TONIGHT BUT ONCE AGAIN EXPECT PRECIP POTENTIAL TO REMAIN
RATHER LOW WITH THE BULK OF 12Z GUIDANCE HOLDING ACTIVITY SOUTH OF
THE MICHIGAN BORDER.
FOR DTW...ALTHOUGH CONFIDENCE IN TSTORMS HAS DECREASED...IT AT LEAST
REMAINS PLAUSIBLE. THE BEST TIME FOR A THUNDERSTORM TO IMPACT THE
AIRPORT WILL BE 21Z-23Z THIS AFTERNOON. CONFIDENCE IN SHOWER
COVERAGE TOWARD MORNING IS ALSO QUITE LOW. ELECTED TO ELIMINATE
SPECIFIC MENTION FROM THE TAF UNTIL POTENTIALLY IMPACTED AREA BECOMES
MORE CLEAR.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILINGS BELOW 5KFT THIS AFTERNOON AND LATE TONIGHT
* LOW CONFIDENCE THAT A TSTORM WILL IMPACT KDTW
&&
.PREV DISCUSSION...ISSUED 1227 PM EDT MON SEP 1 2014
UPDATE...
MOST OF SOUTHEAST MICHIGAN REMAINS SHROUDED IN LOW AND MID-LEVEL
CLOUDS EARLY THIS AFTERNOON, ALTHOUGH THE LATEST TRENDS ON VISIBLE
INDICATE THAT THE STRATUS DECK HAS BEGUN TO EVOLVE TOWARD A
DIURNALLY FORCED CU FIELD. AS A RESULT, TEMPERATURES HAVE RISEN INTO
THE MID TO UPPER 70S FROM WESTERN LOWER MI NORTHEASTWARD INTO THE
THUMB WHILE DEWPOINTS REMAIN LOCKED IN AROUND 70 DEGREES.
THE STOUT 600MB CAP INDICATED ON THIS MORNING`S SOUNDING REMAINS THE
ONLY IMPEDANCE, ALBEIT A POTENTIALLY SIGNIFICANT ONE, TO WIDESPREAD
SEVERE WEATHER THIS AFTERNOON. CAP NOTWITHSTANDING, THERMODYNAMIC
PROFILES ARE IMPRESSIVE. MODERATE DESTABILIZATION IS STILL FAVORED
GIVEN THE ABUNDANCE OF LOW-LEVEL MOISTURE AND SURFACE TEMPERATURES
ALREADY PUSHING UPPER 70S AT NOON. 0-6KM BULK SHEAR FEATURING
VEERING THROUGH THE LOWEST 1.5KM AGL AND AFOREMENTIONED DEGREE OF
DESTABILIZATION WILL SUPPORT AN INITIAL CONVECTIVE MODE OF
SUPERCELLS. ANY SUPERCELLS WILL CARRY TORNADIC POTENTIAL GIVEN
FAVORABLE THERMODYNAMIC PROFILES FOR STRETCHING IN THE LOWEST
LEVELS, VEERED SFC-1KM WIND PROFILES, AND REASONABLY LOW LCLS OF
700-900M. UNIDIRECTIONAL MID-LEVEL WIND PROFILE AND PLENTY DRY AIR
WOULD THEN SUPPORT A QUICK EVOLUTION TOWARD DOWNDRAFT MODULATED
CONVECTION AND A CORRESPONDING EVOLUTION TOWARD DYNAMIC BOWS EARLY
IN THE CONVECTIVE CYCLE. GIVEN THE HIGH FREEZING LEVELS, THE LACK
OF MESOCYCLONE FORCING WITHIN BOWS WILL TEND TO LIMIT THE THREAT
TO WIND ONLY.
IN SPITE OF THE RIPE ENVIRONMENT, CAPPING LOOMS LARGE. THE 12Z NAM12
ALLOWS ENCROACHING HEIGHT FALLS TO USHER IN SUFFICIENT MID-LEVEL
COOLING SUPPORTIVE OF STRONG, DEEP CONVECTION THROUGH THE
EARLY/MID AFTERNOON. AT THE SAME TIME, THE LAST SEVERAL RUNS OF
THE RAP IS CONSIDERABLY SLOWER COOLING THE COLUMN AND LIMITS ANY
SEVERE THREAT TO THE SAGINAW VALLEY AREA WHERE MID-LEVEL
COOLING/FORCING WILL BE MAXIMIZED. THE SOLUTION SPACE REMAINS WIDE
OPEN AND CONFIDENCE IN SEVERE WX IS CORRESPONDINGLY LOW. AT THIS
POINT, EVEN COVERAGE OF CONVECTION SEEMS TO BE IN QUESTION,
PARTICULARLY IF THE LATEST NON NAM GUIDANCE IS TO BE BELIEVED. IN
PURSUIT OF CLARITY, AN 18Z SOUNDING IS FORTHCOMING.
PREV DISCUSSION...ISSUED 405 AM EDT MON SEP 1 2014
SHORT TERM... TODAY AND TONIGHT
THUNDERSTORMS AND THE POTENTIAL FOR SEVERE WEATHER WILL BE THE
PRIMARY SUBJECT OF THE FORECAST FOR TODAY AND TONIGHT AS INGREDIENTS
COME TOGETHER FOR AN ACTIVE AFTERNOON AND EVENING AROUND SE
MICHIGAN. A FEW ELEVATED SHOWERS OR WEAK THUNDERSTORMS WILL BE
POSSIBLE DURING THE MORNING AS THE WARM SECTOR OF THE BROAD LOW
PRESSURE SYSTEM BUILDS INTO LOWER MICHIGAN. EXPECT THIS TO BE
FOLLOWED BY SURFACE BASED STORMS LIKELY INITIATING IN THE LEE OF
LAKE MICHIGAN EARLY TO MID AFTERNOON AND PROGRESSING THROUGH SE
MICHIGAN AS THE LEADING EDGE OF THE UPPER WAVE/MCV REMNANTS INTERACT
WITH THE LOW LEVEL MOISTURE AXIS DURING PEAK HEATING. A SECOND ROUND
OF STORMS IS THEN LIKELY TO INITIATE ALONG AND AHEAD OF THE COLD
FRONT AND FOLLOW THE AFTERNOON STORMS THROUGH OUR AREA MID EVENING
THROUGH THE OVERNIGHT.
EARLY MORNING IR SATELLITE IMAGERY INDICATES STRONGLY WARMING CLOUD
TOPS ASSOCIATED WITH THE UPSTREAM CONVECTION WHICH SUPPORTS THE
DISSIPATING TREND ADVERTISED IN MODEL DATA AND THE SCENARIO OF NEW
DEVELOPMENT OVER LOWER MICHIGAN DURING THE DAY. THIS DISSIPATING
TREND IS HAPPENING SOON ENOUGH TO ALLOW DEBRIS CLOUDS TO ERODE
AND/OR GET CARRIED TO OUR WEST AND NORTH BY THE SOUTHWEST FLOW
ALOFT. THAT LEAVES JUST PATCHY MID CLOUDS...ALONG WITH AREAS OF FOG
AND LOW STRATUS...AS A MINIMAL OBSTRUCTION TO STRONG SURFACE HEATING
TO START THE DAY. IT THEN SEEMS REASONABLE TO ASSUME MAX TEMPS OF
80-85 WILL BE REACHABLE WITH SURFACE DEWPOINT AROUND 70 CARRYING
0-1KM LAYER CAPE TOWARD 1500 J/KG. A SURFACE PARCEL AT 85/72
GENERATES SURFACE BASED CAPE NEAR 2500 J/KG AS A WORST CASE
SCENARIO. THESE VALUES ARE PLENTY HIGH ENOUGH TO INTERACT WITH A
STRENGTHENING UNIDIRECTIONAL WIND PROFILE INCREASING TO NEAR 40 KNOTS
OF BULK SHEAR IN THE 0-6KM LAYER...WITH MOST OF THAT IN THE 0-3KM
LAYER. THIS WILL ALLOW DISCRETE CELLS TO DEVELOP SUPERCELL CHARACTER
EARLY ON WITH SPLITS AND MERGERS GROWING UPSCALE INTO LINEAR SEGMENTS
AS CONVECTION MATURES LATE AFTERNOON INTO EARLY EVENING. DAMAGING
WIND WILL BE THE PRIMARY HAZARD. LARGE HAIL WILL BE POSSIBLE BUT
LIKELY LIMITED TO ONLY THE STRONGEST MESO ENHANCED UPDRAFTS DUE TO
HIGH FREEZING LEVEL. IT IS ALSO IMPORTANT TO NOTE THAT MODEL
SOUNDINGS INDICATE CAPE EXCEEDING 300 J/KG IN THE LOWEST 3 KM ALONG
WITH 0-3 KM HELICITY AROUND 200 M2/S2 AND LCL BETWEEN 3500 AND 4000
FT. THESE ARE FAVORABLE PARAMETERS FOR TORNADOGENESIS.
ROUND TWO OF STORMS WILL BE TRIGGERED BY THE COLD FRONT WEST OF LAKE
MICHIGAN DURING THE LATE AFTERNOON. SEVERE POTENTIAL WITH THIS
ACTIVITY WILL BE LOWER BY THE TIME IT REACHES OUR AREA TOWARD LATE
EVENING INTO THE OVERNIGHT...BOTH DUE TO THE DOWNSIDE OF DAYTIME
HEATING AND THE PRECEDING STORMS. HEAVY RAINFALL MAY END UP BEING
THE MAIN CONCERN AS THE THE SLOW MOVING COLD FRONT ENDS UP THE FOCUS
OF LARGE SCALE SUPPORT FROM THE ENTRANCE REGION OF THE UPPER JET AND
CONTINUED LOW LEVEL MOISTURE TRANSPORT. THIS WILL DEPEND ON HOW MUCH
POST FRONTAL/ELEVATED CONVECTION IS ABLE TO OCCUR WHICH THE MODELS
SUGGEST WILL BE MINIMAL...INSTEAD FOCUSING ADDITIONAL RAINFALL ALONG
AND AHEAD OF THE FRONT THROUGH SUNRISE TUESDAY.
LONG TERM...
WARMER/ABOVE NORMAL TEMPERATURES APPEAR TO BE IN STORE FOR THE FIRST
SEVERAL DAYS OF SEPTEMBER.
BROAD UPPER LEVEL TROUGH WILL BE SWINGING THROUGH THE CENTRAL GREAT
LAKES ON TUESDAY...AND IT APPEARS THE SURFACE COLD FRONT/MOISTURE
AXIS WILL HAVE CLEARED SOUTHEAST MICHIGAN AROUND 12Z TUESDAY...WITH
A DRAMATIC DRYING TREND TAKING PLACE AS PW VALUES AROUND 2 INCHES
NEAR THE OHIO BORDER ARE JUST ABOUT CUT IN HALF TO AROUND 1 INCH.
HOWEVER...THERE IS AN EMBEDDED STRONG SHORTWAVE QUICKLY TRACKING OUT
OF EASTERN IOWA EARLY TUESDAY MORNING...AND NEED TO ACCOUNT FOR THE
POSSIBILITY OF THE FLOW OUT AHEAD OF THIS FEATURE A BIT MORE
BACKED...SLOWING THE PROGRESS OF THE FRONTAL BOUNDARY TO THE
SOUTH...AND CARRY LOW CHANCE POPS...AS DAYTIME SURFACE BASED
INSTABILITY SETS IN AS WELL...WITH AROUND 1000 J/KG TO WORK WITH PER
00Z NAM. ALTHOUGH...THE 00Z GFS IS DRIER AND DECIDEDLY MORE
ANTICYCLONIC AT THE SURFACE...WHILE THE CANADIAN IS THE WETTEST.
SHORT LIVED ENERGETIC ZONAL FLOW OVER THE NORTHERN CONUS TUESDAY
NIGHT WITH STRONGER UPPER WAVE DIVING SOUTHEAST THROUGH THE PACIFIC
NORTHWEST. HEIGHTS WILL REBOUND OVER THE EASTERN CONUS
WEDNESDAY/THURSDAY WITH FAVORABLE DEEP SOUTHWEST FLOW AROUND SURFACE
HIGH CENTERED OVER THE EASTERN SEABOARD. HIGHS THE 80S APPEAR IN
THE OFFING...AS 850 MB TEMPS RISE TOWARD 20 C ON THURSDAY...AND
REACH OR POSSIBLY SLIGHTLY EXCEED 20 C ON FRIDAY...WHICH MAKES A RUN
TOWARD A 90 DEGREE DAY A REAL POSSIBILITY. HOWEVER...A COLD FRONT
WILL PROBABLY ALREADY BE ARRIVING...SUPPORTING CLOUDS AND A GOOD
CHANCE OF SHOWERS AND THUNDERSTORMS...WHICH OF COURSE WOULD HINDER
MAXES. MUCH LOWER CHANCE OF PRECIPITATION ON THURSDAY AS WARM FRONT
LIFTS THROUGH THE WESTERN GREAT LAKES.
MARINE...
SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON...AND CONTINUE
TONIGHT AS A COLD FRONT MOVES THROUGH LAKE HURON AND LOWER MICHIGAN.
SOME OF THESE STORMS MAY BE SEVERE. HIGH PRESSURE WILL BUILD INTO
THE REGION BEHIND THIS FRONT ON TUESDAY...WHICH WILL REMAIN IN
CONTROL OF THE WEATHER THROUGH THURSDAY...PROVIDING FAVORABLE
BOATING CONDITIONS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....JVC
UPDATE.......JVC
SHORT TERM...BT
LONG TERM....SF
MARINE.......SF
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1237 PM EDT MON SEP 1 2014
LATEST UPDATE...
HYDRO
.SYNOPSIS...
ISSUED AT 330 AM EDT MON SEP 1 2014
A COLD FRONT WILL MOVE INTO THE GREAT LAKES REGION FROM THE WEST
LATER TODAY AND INTO TONIGHT. SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO DEVELOP OVER SOUTHWEST LOWER MICHIGAN FROM THE LATE MORNING HOURS
PERSISTING INTO THE EVENING. SOME OF THE STORMS FROM THE MIDDAY
HOURS THROUGH THE EVENING MAY BE SEVERE WITH LARGE HAIL AND STRONG
WINDS. SHOWERS AND STORMS WILL GRADUALLY TAPER OFF TONIGHT
FROM NORTH TO SOUTH AS THE FRONT DROPS SOUTHWARD INTO INDIANA. DRY
WEATHER IS THEN EXPECTED FOR THE MOST PART FROM TUESDAY THROUGH
WEDNESDAY. CHANCES FOR SHOWERS AND STORMS INCREASE ONCE AGAIN
WEDNESDAY NIGHT THROUGH FRIDAY AS A LOW PRESSURE SYSTEM TRAVERSES
THE AREA. TEMPERATURES THIS WEEK WILL BE NEAR TO ABOVE NORMAL WITH
HIGHS IN THE UPPER 70S TO 80S ALL WEEK. A COOL DOWN IS EXPECTED NEXT
WEEKEND BEHIND A COLD FRONT THAT MOVES THROUGH ON FRIDAY.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 1100 AM EDT MON SEP 1 2014
ISOLATED SEVERE WEATHER THREAT CONTINUES THIS AFTERNOON (2PM - 8PM)
EAST OF U.S. 131 WITH DAMAGING WIND GUSTS THE MAIN THREAT. BRIEF
LOCALIZED FLOODING TYPICAL OF STRONG THUNDERSTORMS IS ALSO POSSIBLE.
APPROACHING WEAK FRONTAL BOUNDARY...SEPARATING DEWPOINTS IN THE LOW
70S FROM THOSE IN THE MID 60S...IS CURRENTLY ORIENTED NORTH-SOUTH
ACROSS EASTERN WISCONSIN AND ILLINOIS. THERE IS ALSO CONSIDERABLE
CLOUDINESS ALONG AND AHEAD OF FRONT WHICH IS TEMPERATURES AND
DESTABILIZATION OFTHE AIRMASS.
THE FRONT WILL SWEEP EASTWARD ACROSS THE CWA THIS AFTERNOON AND
EARLY EVENING PROVIDING LOW LEVEL LIFT AND POTENTIAL FOCUS FOR
DEVELOPMENT OF NEW STORMS. ALOFT HOWEVER...THE LEAD SHORTWAVE AND
NOSE OF UPPER JET WILL PUSH EASTWARD OVER THE REGION WITH BEST DEEP
LIFT NORTH MAINLY NORTH OF THE AREA.
INSTABILITY AND WIND FIELDS ARE FAVORABLE FOR SEVERE STORMS WITH
CAPE VALUES OF 500 - 1500 J/KG...0-6 KM BULK SHEAR VALUES NEAR 40
KTS...AND 0-1KM SHEAR VALUES AROUND 20 KTS. HOWEVER...LACK OF DEEP
LIFT WILL LIMIT COVERAGE OF STORMS AND OVERALL SEVERE THEAT
SIGNICANTLY. THIS SOLUTION IS REFLECTED IN MANY OF THE HIGHER
RESOLUTION CONVECTION ALLOWING MODELS INCLUDING LAST FEW NSSL WRF
AND HRRR RUNS.
OTHERWISE...THE SHORT TERM IS RELATIVELY QUIET. ANY STORMS THIS
EVENING SHOULD WORK SOUTH OF THE AREA OVERNIGHT. NOT OUT OF THE
REALM OF POSSIBILITIES FOR A FEW SHOWERS ON TUESDAY...BUT FELT THE
THREAT WAS SMALL ENOUGH TO GO DRY. TUESDAY NIGHT AND WEDNESDAY
SHOULD BE DRY WITH RIDGING IN PLACE AT THE SURFACE.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON SEP 1 2014
THE MOST UNSETTLED WEATHER IN THE LONG TERM LOOKS TO OCCUR IN THE
FIRST COUPLE OF DAYS...FROM THE BEGINNING OF THE PERIOD WED NIGHT
INTO FRI NIGHT. THE LATEST TREND IS FOR A LITTLE MORE POSSIBLE PCPN
WED NIGHT INTO THU WITH THE PASSAGE OF THE WARM FRONT THROUGH THE
AREA. THIS LOOKS TO BE THE CASE DUE TO THE GRADIENT/LOW LEVEL JET
EXPECTED TO BE A LITTLE STRONGER WITH A STRONGER TROUGH MOVING IN.
HOW QUICKLY THE FRONT MOVES THROUGH WILL DICTATE HOW WARM WE GET ON
THU. IF THE FRONT MOVES QUICK ENOUGH...WE COULD HAVE A CHC TO WARM
TOWARD 90 WITH H850 TEMPS OF 20C ADVECTING IN. FOR NOW...WE HAVE
SETTLED WITH THE MID-UPPER 80S WITH THE UNCERTAINTY OF THE PCPN.
WE WILL SEE ANOTHER BATCH OF CONVECTION BE POSSIBLE THEN CENTERED
AROUND FRI AS THE COLD FRONT PUSHES THROUGH AND ENCOUNTERING THE
VERY WARM AND MOIST AIR MASS. WE COULD HAVE SOME ASSISTANCE VIA THE
RRQ OF AN UPPER JET TO OUR N/NE THAT WOULD SUPPLEMENT THE COLD
FRONTAL PASSAGE.
THE REMAINDER OF THE LONG TERM FROM SAT THROUGH SUN LOOKS TO BE
RATHER QUIET...YET COOL. WE WILL SEE A CANADIAN AIR MASS FILTER IN
BEHIND THE THU/FRI SYSTEM WITH A DECENT NNE LOW LEVEL FLOW USHERING
IT IN. THE UPPER FLOW WILL BE FROM THE NW AND A BIT OF A TROUGH WILL
BE OVER THE AREA. THE FAR ERN FLANK OF A SFC RIDGE WILL BE
BUILDING IN AS THE SYNOPTIC PATTERN OVER THE COUNTRY WILL FEATURE A
FAIRLY BROAD/EXPANSIVE UPPER RIDGE FROM THE ERN PACIFIC INTO THE
ROCKIES. THIS SHOULD KEEP THE AREA DRY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 749 AM EDT MON SEP 1 2014
COMPLICATED WEATHER SCENARIO IN PLACE THIS MORNING WITH STRATUS
MOVING NORTH THROUGH THE TAF SITES AND THE POTENTIAL FOR
THUNDERSTORMS LOOMING.
THE STRATUS AND FOG SHOULD GRADUALLY LIFT THROUGH THE COURSE OF
THE MORNING...BUT IT HAS BECOME FAIRLY EXTENSIVE ACROSS SOUTHERN
LOWER MICHIGAN. BY AFTERNOON...EXPECTING VFR CEILINGS AND VSBYS
OUTSIDE OF THUNDERSTORMS.
AS FOR THUNDERSTORMS...THEY ARE ALREADY DEVELOPING ACROSS
PORTIONS OF NORTHERN ILLINOIS AND NORTHERN INDIANA. THE TREND
SHOULD BE FOR SCATTERED SHOWERS AND THUNDERSTORMS TO MOVE THROUGH
THE TAF SITES FROM 14Z OR SO THROUGH 23Z. TOO DIFFICULT TO NAIL
DOWN PREVAILING TIMING AT THIS POINT GIVEN THE HIT OR MISS NATURE
TO TODAY/S STORMS...SO HAVE VCTS WORDING IN ALL THE TAFS THIS
AFTERNOON.
OVERNIGHT...EXPECTING THE SHOWERS AND STORMS TO END WITH MVFR
CEILINGS TRYING TO SETTLE BACK IN.
IT WILL BECOME WINDY TODAY OUT OF THE SOUTH-SOUTHWEST...ESPECIALLY
FROM 15Z-23Z. WINDS FROM 200-220 AT 15-25 KNOTS SHOULD BE COMMON.
&&
.MARINE...
ISSUED AT 1100 AM EDT MON SEP 1 2014
SCA/BEACH HAZARD WORKING WELL WITHWIND GUSTS NEAR 30 KTS AND WAVE
AROUND 4 FT OBSERVED NORTH OF HOLLAND TOWARDS LUDINGTON AT THIS
TIME. WINDS WILL CONTINUE NEXT SEVERAL HOURS WITH WAVES UP TO 5
FEET. WINDS / WAVES WILL SUBSIDE QUICKLY LATE THIS AFTERNOON WITH
PASSAGE OF FRONT AND SHIFT OF WINDS TO A MORE WESTERLY DIRECTION.
THE NEXT POSSIBLE SET OF HEADLINES THAT MAY BE NEEDED FOR THE
NEARSHORE WATERS LOOKS TO START IN THE WED NIGHT/THU TIME FRAME AS
THE FLOW STRENGTHENS WITH A SURGE OF WARMER AIR WITH THE NEXT
FRONTAL SYSTEM POISED TO MOVE IN.
&&
.HYDROLOGY...
ISSUED AT 1237 PM EDT MON SEP 1 2014
RIVERS ARE RUNNING A LITTLE ABOVE NORMAL... BUT ARE STILL FAR BELOW
BANK FULL. PRECIPITATION THROUGH THIS EVENING IS EXPECTED TO TOTAL
AROUND A QUARTER OF AN INCH WITH ISOLATED LOCATIONS NORTHWEST OF
GRAND RAPIDS RECEIVING NEARLY AN INCH. THIS SHOULD LEAD TO SMALL
RISES ON AREA RIVERS WITH PEAK LEVELS BELOW BANK FULL BY MID WEEK.
ADDITIONAL PRECIPITATION IS POSSIBLE WEDNESDAY INTO FRIDAY NIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 10 PM EDT THIS EVENING FOR MIZ037-
043-050-056-064-071.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
SYNOPSIS...DUKE
SHORT TERM...COBB
LONG TERM...NJJ
AVIATION...DUKE
HYDROLOGY...63
MARINE...COBB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1227 PM EDT MON SEP 1 2014
.UPDATE...
MOST OF SOUTHEAST MICHIGAN REMAINS SHROUDED IN LOW AND MID-LEVEL
CLOUDS EARLY THIS AFTERNOON, ALTHOUGH THE LATEST TRENDS ON VISIBLE
INDICATE THAT THE STRATUS DECK HAS BEGUN TO EVOLVE TOWARD A
DIURNALLY FORCED CU FIELD. AS A RESULT, TEMPERATURES HAVE RISEN INTO
THE MID TO UPPER 70S FROM WESTERN LOWER MI NORTHEASTWARD INTO THE
THUMB WHILE DEWPOINTS REMAIN LOCKED IN AROUND 70 DEGREES.
THE STOUT 600MB CAP INDICATED ON THIS MORNING`S SOUNDING REMAINS THE
ONLY IMPEDANCE, ALBEIT A POTENTIALLY SIGNIFICANT ONE, TO WIDESPREAD
SEVERE WEATHER THIS AFTERNOON. CAP NOTWITHSTANDING, THERMODYNAMIC
PROFILES ARE IMPRESSIVE. MODERATE DESTABILIZATION IS STILL FAVORED
GIVEN THE ABUNDANCE OF LOW-LEVEL MOISTURE AND SURFACE TEMPERATURES
ALREADY PUSHING UPPER 70S AT NOON. 0-6KM BULK SHEAR FEATURING
VEERING THROUGH THE LOWEST 1.5KM AGL AND AFOREMENTIONED DEGREE OF
DESTABILIZATION WILL SUPPORT AN INITIAL CONVECTIVE MODE OF
SUPERCELLS. ANY SUPERCELLS WILL CARRY TORNADIC POTENTIAL GIVEN
FAVORABLE THERMODYNAMIC PROFILES FOR STRETCHING IN THE LOWEST
LEVELS, VEERED SFC-1KM WIND PROFILES, AND REASONABLY LOW LCLS OF
700-900M. UNIDIRECTIONAL MID-LEVEL WIND PROFILE AND PLENTY DRY AIR
WOULD THEN SUPPORT A QUICK EVOLUTION TOWARD DOWNDRAFT MODULATED
CONVECTION AND A CORRESPONDING EVOLUTION TOWARD DYNAMIC BOWS EARLY
IN THE CONVECTIVE CYCLE. GIVEN THE HIGH FREEZING LEVELS, THE LACK
OF MESOCYCLONE FORCING WITHIN BOWS WILL TEND TO LIMIT THE THREAT
TO WIND ONLY.
IN SPITE OF THE RIPE ENVIRONMENT, CAPPING LOOMS LARGE. THE 12Z NAM12
ALLOWS ENCROACHING HEIGHT FALLS TO USHER IN SUFFICIENT MID-LEVEL
COOLING SUPPORTIVE OF STRONG, DEEP CONVECTION THROUGH THE
EARLY/MID AFTERNOON. AT THE SAME TIME, THE LAST SEVERAL RUNS OF
THE RAP IS CONSIDERABLY SLOWER COOLING THE COLUMN AND LIMITS ANY
SEVERE THREAT TO THE SAGINAW VALLEY AREA WHERE MID-LEVEL
COOLING/FORCING WILL BE MAXIMIZED. THE SOLUTION SPACE REMAINS WIDE
OPEN AND CONFIDENCE IN SEVERE WX IS CORRESPONDINGLY LOW. AT THIS
POINT, EVEN COVERAGE OF CONVECTION SEEMS TO BE IN QUESTION,
PARTICULARLY IF THE LATEST NON NAM GUIDANCE IS TO BE BELIEVED. IN
PURSUIT OF CLARITY, AN 18Z SOUNDING IS FORTHCOMING.
&&
.AVIATION...ISSUED 703 AM EDT MON SEP 1 2014
//DISCUSSION...
FOG AND STRATUS IN THE WARM AND HUMID AIR OVER SE MICHIGAN WILL
PRESENT LIFR/IFR CONDITIONS AS THE FIRST CONCERN FOR AVIATION
INTERESTS. INCREASING SOUTH TO SOUTHWEST WIND AND SURFACE HEATING
WILL HELP LIFT THE FOG AND MIX THE LOW CLOUDS DURING THE MORNING.
THUNDERSTORMS WILL THEN BECOME THE MAIN CHALLENGE DURING THE
AFTERNOON AND TONIGHT. TWO ROUNDS OF STORMS ARE LIKELY TO AFFECT
THE ENTIRE TERMINAL CORRIDOR...FIRST DURING THE MID AFTERNOON TO
MID EVENING DURING THE WARMEST PART OF THE DAY...AND THEN FROM
LATE EVENING THROUGH THE OVERNIGHT AS A COLD FRONT MOVES SLOWLY
ACROSS SE MICHIGAN. THE MAIN AREA OF RAIN WILL BE ON TRACK TO EXIT
TO THE SOUTH AND EAST BY SUNRISE TUESDAY LEAVING BEHIND ANOTHER
ROUND OF FOG AND STRATUS BEHIND THE COLD FRONT.
FOR DTW... A STRAY SHOWER OR THUNDERSTORM WILL BE POSSIBLE DURING
THE MORNING AND EARLY AFTERNOON BUT THE MAIN WINDOW FOR STORMS AND
POSSIBLE SEVERE WEATHER REMAINS LATE AFTERNOON THROUGH EARLY EVENING
FOR DTW.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET DURING THE MORNING.
* MEDIUM CONFIDENCE IN THUNDERSTORM TIMING AND COVERAGE.
&&
.PREV DISCUSSION...ISSUED 405 AM EDT MON SEP 1 2014
SHORT TERM... TODAY AND TONIGHT
THUNDERSTORMS AND THE POTENTIAL FOR SEVERE WEATHER WILL BE THE
PRIMARY SUBJECT OF THE FORECAST FOR TODAY AND TONIGHT AS INGREDIENTS
COME TOGETHER FOR AN ACTIVE AFTERNOON AND EVENING AROUND SE
MICHIGAN. A FEW ELEVATED SHOWERS OR WEAK THUNDERSTORMS WILL BE
POSSIBLE DURING THE MORNING AS THE WARM SECTOR OF THE BROAD LOW
PRESSURE SYSTEM BUILDS INTO LOWER MICHIGAN. EXPECT THIS TO BE
FOLLOWED BY SURFACE BASED STORMS LIKELY INITIATING IN THE LEE OF
LAKE MICHIGAN EARLY TO MID AFTERNOON AND PROGRESSING THROUGH SE
MICHIGAN AS THE LEADING EDGE OF THE UPPER WAVE/MCV REMNANTS INTERACT
WITH THE LOW LEVEL MOISTURE AXIS DURING PEAK HEATING. A SECOND ROUND
OF STORMS IS THEN LIKELY TO INITIATE ALONG AND AHEAD OF THE COLD
FRONT AND FOLLOW THE AFTERNOON STORMS THROUGH OUR AREA MID EVENING
THROUGH THE OVERNIGHT.
EARLY MORNING IR SATELLITE IMAGERY INDICATES STRONGLY WARMING CLOUD
TOPS ASSOCIATED WITH THE UPSTREAM CONVECTION WHICH SUPPORTS THE
DISSIPATING TREND ADVERTISED IN MODEL DATA AND THE SCENARIO OF NEW
DEVELOPMENT OVER LOWER MICHIGAN DURING THE DAY. THIS DISSIPATING
TREND IS HAPPENING SOON ENOUGH TO ALLOW DEBRIS CLOUDS TO ERODE
AND/OR GET CARRIED TO OUR WEST AND NORTH BY THE SOUTHWEST FLOW
ALOFT. THAT LEAVES JUST PATCHY MID CLOUDS...ALONG WITH AREAS OF FOG
AND LOW STRATUS...AS A MINIMAL OBSTRUCTION TO STRONG SURFACE HEATING
TO START THE DAY. IT THEN SEEMS REASONABLE TO ASSUME MAX TEMPS OF
80-85 WILL BE REACHABLE WITH SURFACE DEWPOINT AROUND 70 CARRYING
0-1KM LAYER CAPE TOWARD 1500 J/KG. A SURFACE PARCEL AT 85/72
GENERATES SURFACE BASED CAPE NEAR 2500 J/KG AS A WORST CASE
SCENARIO. THESE VALUES ARE PLENTY HIGH ENOUGH TO INTERACT WITH A
STRENGTHENING UNIDIRECTIONAL WIND PROFILE INCREASING TO NEAR 40 KNOTS
OF BULK SHEAR IN THE 0-6KM LAYER...WITH MOST OF THAT IN THE 0-3KM
LAYER. THIS WILL ALLOW DISCRETE CELLS TO DEVELOP SUPERCELL CHARACTER
EARLY ON WITH SPLITS AND MERGERS GROWING UPSCALE INTO LINEAR SEGMENTS
AS CONVECTION MATURES LATE AFTERNOON INTO EARLY EVENING. DAMAGING
WIND WILL BE THE PRIMARY HAZARD. LARGE HAIL WILL BE POSSIBLE BUT
LIKELY LIMITED TO ONLY THE STRONGEST MESO ENHANCED UPDRAFTS DUE TO
HIGH FREEZING LEVEL. IT IS ALSO IMPORTANT TO NOTE THAT MODEL
SOUNDINGS INDICATE CAPE EXCEEDING 300 J/KG IN THE LOWEST 3 KM ALONG
WITH 0-3 KM HELICITY AROUND 200 M2/S2 AND LCL BETWEEN 3500 AND 4000
FT. THESE ARE FAVORABLE PARAMETERS FOR TORNADOGENESIS.
ROUND TWO OF STORMS WILL BE TRIGGERED BY THE COLD FRONT WEST OF LAKE
MICHIGAN DURING THE LATE AFTERNOON. SEVERE POTENTIAL WITH THIS
ACTIVITY WILL BE LOWER BY THE TIME IT REACHES OUR AREA TOWARD LATE
EVENING INTO THE OVERNIGHT...BOTH DUE TO THE DOWNSIDE OF DAYTIME
HEATING AND THE PRECEDING STORMS. HEAVY RAINFALL MAY END UP BEING
THE MAIN CONCERN AS THE THE SLOW MOVING COLD FRONT ENDS UP THE FOCUS
OF LARGE SCALE SUPPORT FROM THE ENTRANCE REGION OF THE UPPER JET AND
CONTINUED LOW LEVEL MOISTURE TRANSPORT. THIS WILL DEPEND ON HOW MUCH
POST FRONTAL/ELEVATED CONVECTION IS ABLE TO OCCUR WHICH THE MODELS
SUGGEST WILL BE MINIMAL...INSTEAD FOCUSING ADDITIONAL RAINFALL ALONG
AND AHEAD OF THE FRONT THROUGH SUNRISE TUESDAY.
LONG TERM...
WARMER/ABOVE NORMAL TEMPERATURES APPEAR TO BE IN STORE FOR THE FIRST
SEVERAL DAYS OF SEPTEMBER.
BROAD UPPER LEVEL TROUGH WILL BE SWINGING THROUGH THE CENTRAL GREAT
LAKES ON TUESDAY...AND IT APPEARS THE SURFACE COLD FRONT/MOISTURE
AXIS WILL HAVE CLEARED SOUTHEAST MICHIGAN AROUND 12Z TUESDAY...WITH
A DRAMATIC DRYING TREND TAKING PLACE AS PW VALUES AROUND 2 INCHES
NEAR THE OHIO BORDER ARE JUST ABOUT CUT IN HALF TO AROUND 1 INCH.
HOWEVER...THERE IS AN EMBEDDED STRONG SHORTWAVE QUICKLY TRACKING OUT
OF EASTERN IOWA EARLY TUESDAY MORNING...AND NEED TO ACCOUNT FOR THE
POSSIBILITY OF THE FLOW OUT AHEAD OF THIS FEATURE A BIT MORE
BACKED...SLOWING THE PROGRESS OF THE FRONTAL BOUNDARY TO THE
SOUTH...AND CARRY LOW CHANCE POPS...AS DAYTIME SURFACE BASED
INSTABILITY SETS IN AS WELL...WITH AROUND 1000 J/KG TO WORK WITH PER
00Z NAM. ALTHOUGH...THE 00Z GFS IS DRIER AND DECIDEDLY MORE
ANTICYCLONIC AT THE SURFACE...WHILE THE CANADIAN IS THE WETTEST.
SHORT LIVED ENERGETIC ZONAL FLOW OVER THE NORTHERN CONUS TUESDAY
NIGHT WITH STRONGER UPPER WAVE DIVING SOUTHEAST THROUGH THE PACIFIC
NORTHWEST. HEIGHTS WILL REBOUND OVER THE EASTERN CONUS
WEDNESDAY/THURSDAY WITH FAVORABLE DEEP SOUTHWEST FLOW AROUND SURFACE
HIGH CENTERED OVER THE EASTERN SEABOARD. HIGHS THE 80S APPEAR IN
THE OFFING...AS 850 MB TEMPS RISE TOWARD 20 C ON THURSDAY...AND
REACH OR POSSIBLY SLIGHTLY EXCEED 20 C ON FRIDAY...WHICH MAKES A RUN
TOWARD A 90 DEGREE DAY A REAL POSSIBILITY. HOWEVER...A COLD FRONT
WILL PROBABLY ALREADY BE ARRIVING...SUPPORTING CLOUDS AND A GOOD
CHANCE OF SHOWERS AND THUNDERSTORMS...WHICH OF COURSE WOULD HINDER
MAXES. MUCH LOWER CHANCE OF PRECIPITATION ON THURSDAY AS WARM FRONT
LIFTS THROUGH THE WESTERN GREAT LAKES.
MARINE...
SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON...AND CONTINUE
TONIGHT AS A COLD FRONT MOVES THROUGH LAKE HURON AND LOWER MICHIGAN.
SOME OF THESE STORMS MAY BE SEVERE. HIGH PRESSURE WILL BUILD INTO
THE REGION BEHIND THIS FRONT ON TUESDAY...WHICH WILL REMAIN IN
CONTROL OF THE WEATHER THROUGH THURSDAY...PROVIDING FAVORABLE
BOATING CONDITIONS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......JVC
AVIATION.....BT
SHORT TERM...BT
LONG TERM....SF
MARINE.......SF
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 PM EDT MON SEP 1 2014
.SYNOPSIS...AN AREA OF HIGH PRESSURE WILL EXTEND OVER THE REGION
THROUGH TUESDAY. A WEAK SURFACE FRONT WILL SETTLE SOUTHWARD ACROSS
CENTRAL NC ON WEDNESDAY. HIGH PRESSURE WILL BUILD BACK OVER THE AREA
FOR THE REMAINDER OF THE WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 305 PM MONDAY...
LATE THIS AFTERNOON THROUGH TONIGHT... SLIGHT TO MODERATELY UNSTABLE
COVERS CENTRAL NC AT MID AFTERNOON WITH A WEAK SHEAR AXIS SLOWLY
EDGING EASTWARD ACROSS THE REGION. BEST DYNAMICS/LIFT ASSOCIATED
WITH THIS FEATURE WELL NORTH OF OUR REGION AS SHEAR AXIS IS IMPEDING
UPON A MID-UPPER LEVEL RIDGE POSITIONED OVER EASTERN NC. THE RIDGE
WILL CONTINUE TO INHIBIT MOST CONVECTIVE DEVELOPMENT BUT COULD STILL
SEE AN ISOLATED STORM OR TWO DEVELOP ACROSS THE REGION. BASED ON 18Z
MESO-ANALYSIS...ISOLATED CONVECTIVE DEVELOPMENT APPEARS TO BE
FAVORED OVER THE WESTERN PIEDMONT...AND NEAR THE VIRGINIA BORDER
COUNTIES. THIS SCENARIO HAS THE SUPPORT OF THE LATEST HRRR (WHICH
HAS BEEN TRENDING WETTER). THE CONVECTIVE ALLOWING
MODELS...THOUGH...HAVE BEEN TRENDING DRIER AND NOW SUGGEST THAT
ISOLATED CONVECTION WILL OCCUR OUTSIDE OF OUR FORECAST AREA.
WILL LIKELY SEE PATCHES OF FOG DEVELOP AFTER MIDNIGHT...MAINLY OVER
THE COASTAL PLAIN..SANDHILLS AND EASTERN PIEDMONT. HOWEVER DENSE FOG
WILL BE RARE WITH BULK OF THE VISIBILITIES AT OR ABOVE 1-2 MILES.
MIN TEMPS OVERNIGHT NEAR 70-LOWER 70S.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 305 PM MONDAY...
TUESDAY AND TUESDAY NIGHT... MID-UPPER LEVEL RIDGE PROJECTED TO
SLOWLY WEAKEN THIS PERIOD. THIS MAY ALLOW A FEW MORE T-STORMS TO
DEVELOP IN THE SLIGHT-MODERATELY UNSTABLE AIR MASS TUESDAY AFTERNOON-
EVENING. IN ADDITION...A S/W RESPONSIBLE FOR TRIGGERING THE
CONVECTION ACROSS PARTS OF THE MISSOURI VALLEY/OZARKS THIS AFTERNOON-
EVENING WILL APPROACH CENTRAL NC FROM THE NW LATE IN THE DAY. THIS
FEATURE MAY TRIGGER ADDITIONAL ISOLATED-SCATTERED CONVECTION TUESDAY
EVENING ACROSS THE NW PIEDMONT...AND OVERNIGHT TUESDAY INTO EARLY
WEDNESDAY OVER THE REMAINDER OF CENTRAL NC. WHILE FORCING IS BETTER
COMPARED TO THE PAST FEW DAYS...LIFT IS STILL CONSIDERED WEAK-
MARGINAL AT BEST. THUS WILL LIMIT POPS TO NO HIGHER THAN LOW CHANCE.
ANOTHER HOT DAY IN STORE FOR THE REGION. AFTERNOON THICKNESSES WILL
REMAIN 20-25M ABOVE NORMAL...SUPPORTIVE OF HIGH TEMPS IN THE LOW-MID
90S UNDER FULL SUN CONDITIONS. WHEN THE HUMIDITY IS FACTORED
IN...HEAT INDEX VALUES NEAR 100-104 WILL BE COMMON WITH THE HIGHEST
H.I.VALUES IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS. MIN TEMPS
TUESDAY NIGHT GENERALLY IN THE LOWER 70S. -WSS
FOR WED/WED NIGHT: THE WEAK SURFACE REFLECTION THAT REMAINS FROM THE
COLD FRONT APPROACHING CENTRAL NC WILL BECOME EVEN MORE WASHED OUT
AS IT SHIFTS INTO THE LEE TROUGH OVER CENTRAL NC. MODELS SHOW A VERY
WEAK VORTICITY LOBE ASSOCIATED WITH THIS FRONT PUSHING ESE THROUGH
NC EARLY WED... AND ITS APPROACH ALONG WITH LINGERING STRONG LOW
LEVEL MOISTURE TRANSPORT OVER ERN NC SHOULD SUPPORT AN AREA OF
ATYPICAL MORNING SHOWERS/STORMS OVER THE ERN AND ESPECIALLY SE CWA
WED MORNING. THE DEPARTURE AND DAMPENING OF THE MEAN MID LEVEL
TROUGH WELL TO OUR NE WILL RESULT IN MODEST RISING HEIGHTS (15-25 M)
WITHIN THE FLAT (W-E ORIENTED) MID LEVEL RIDGE ACROSS NC THROUGH WED
NIGHT. THE LATEST NAM RUN IS CONSISTENT WITH PREVIOUS RUNS IN
BRINGING LOWER PW (UNDER 1.5") INTO MUCH OF THE CWA FROM THE NW WITH
A BIT STRONGER 850-700 MB NW WIND AS COMPARED TO THE GFS... WHICH
KEEPS PW VALUES UP TO 1.7-1.9". GIVEN THE FACT THAT THE MID LEVEL
TROUGH WILL BE DAMPENING WITH LITTLE REASON TO SUPPORT A STRONG PUSH
OF DRY AIR PAST THE MOUNTAINS... THE GFS`S MORE SUBDUED TROUGH
INFLUENCE APPEARS MORE LIKELY... BASED ON THE PERSISTENCE OF THE
STRONG RIDGE. MODERATE INSTABILITY IS EXPECTED OVER ALL BUT PERHAPS
THE FAR NW... WITH THE GFS SHOWING MUCAPE PEAKING AT 1000-2500 J/KG.
WILL STAY CLOSE TO THE GFS/ECMWF SOLUTION WITH SCATTERED AFTERNOON
THROUGH EVENING STORMS... WITH BEST COVERAGE ACROSS THE SOUTHERN CWA
AND ALONG/EAST OF THE PERSISTENT LEE TROUGH... AS WELL AS ALONG THE
INLAND-TRACKING SEA BREEZE. WITH ABOVE-NORMAL PW AND WEAK MID LEVEL
FLOW... SLOW-MOVERS AND HEAVY-RAINERS ARE POSSIBLE. WITH THICKNESSES
A TAD LOWER THAN TUE BUT REMAINING 12-20 M ABOVE NORMAL... EXPECT
WARM AND STICKY HIGHS OF 91-95... DESPITE A GOOD CHANCE OF DEBRIS
CLOUD COVER THROUGH THE DAY. CONVECTION CHANCES SHOULD RECEDE WED
NIGHT BUT THE GFS INDICATES PLENTY OF ELEVATED BUOYANCY POTENTIAL
OVERNIGHT... INCLUDING MLCAPE OF 500-1000 J/KG RESULTING FROM VERY
WARM 960-920 MB TEMPS. WILL HOLD ONTO CHANCE POPS MAINLY SOUTH HALF
OVERNIGHT. MUGGY LOWS IN THE LOW-MID 70S. -GIH
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 230 PM MONDAY...
FOR THU/FRI: CONTINUED ABOVE-NORMAL WARMTH WITH ONLY MINOR CHANGES
IN AIR MASS. AT THE SURFACE... THE WEAK LEE TROUGH HOLDS THROUGH
CENTRAL NC... ALONG WITH A HUMID AND SOMEWHAT STAGNANT AIR MASS. A
POSITIVELY TILTED TROUGH SHIFTS THROUGH THE PACIFIC NORTHWEST AND SW
CANADA INTO THE DAKOTAS THU... RESULTING IN BUILDING HEIGHTS AND
GRADUAL MID LEVEL WARMING OVER THE SOUTHEAST STATES. THIS POLAR
STREAM TROUGH THEN SHIFTS INTO ERN CANADA... WHILE THE FLAT RIDGE
HOLDS ACROSS NC. WITH PLENTY OF LOW LEVEL MOISTURE POOLING...
ISOLATED TO SCATTERED STORMS FOCUSED ALONG A SEA BREEZE OR SOME
OTHER SUBTLE BOUNDARY REMAIN A GOOD BET... DESPITE THE WARMING TEMPS
ALOFT. WILL RETAIN AFTERNOON AND EVENING STORM CHANCES BOTH DAYS...
WITH TEMPS HOLDING ABOUT A CATEGORY ABOVE NORMAL AS THICKNESSES STAY
10-15 M ABOVE NORMAL.
FOR SAT THROUGH MON: A PATTERN TRANSITION IS LIKELY NEXT WEEKEND.
THE INITIAL MID LEVEL TROUGH CONTINUES HEADING EASTWARD OVER ERN
CANADA EARLY SAT... HOWEVER A SLUG OF STRONG VORTICITY EMANATING
FROM A STRONG COLD VORTEX OVER THE BEAUFORT SEA WILL PUSH EASTWARD
CLOSE ON ITS HEELS... TAKING A COLD FRONT TO NEW ENGLAND AND THE OH
VALLEY BY EARLY SAT. THE RESULTING TROUGH OVER ERN NOAM SUNDAY
SHOULD HELP PUSH THE FRONT SOUTHWARD INTO NC... AFTER WHICH TIME IT
IS APT TO LAY WEST/EAST AND STALL OVER THE CAROLINAS FOR LATE SUN
THROUGH MON. THE GFS HAS A STRONGER/FASTER TIME FRAME THAN THE
ECMWF... WITH THE FORMER MODEL SOLUTION TAKING THICKNESSES MUCH
COLDER... UP TO 25 M BELOW NORMAL AS OPPOSED TO THE ECMWF WHICH IS
BARELY 5 M BELOW NORMAL. TOUGH TO RESOLVE SUCH DIFFERENCES BUT GIVEN
THE STRENGTH OF THE SRN CONUS RIDGE... AND THE FAR-NORTH TRACK OF
THE POLAR LOW... I REMAIN SKEPTICAL ABOUT A STRONG COLD FRONTAL
PASSAGE THROUGH NC. WILL STAY ON THE CONSERVATIVE SIDE OF THE TEMP
TREND... WITH HIGHS/LOWS INITIALLY AROUND 90/AROUND 70 SAT...
SLIPPING TO LOW-MID 80S/UPPER 60S BY MON. PRECIP CHANCES AND
PATTERNS ARE LIKELY TO CHANGE LITTLE THROUGH SUN... PERHAPS
INCREASING IN COVERAGE AS THE FRONT APPROACHES WITH FALLING HEIGHTS
ALOFT... STRENGTHENING (YET STILL SOMEWHAT WEAK) MID LEVEL FLOW...
AND A PERSISTENT CONFLUENT INFLUX OF GULF AND ATLANTIC MOISTURE IN
THE LOW LEVELS. WILL MAINTAIN SCATTERED SHOWERS AND STORMS FOCUSED
ON -- BUT NOT RESTRICTED TO -- AFTERNOON AND EVENING HOURS. WILL
KEEP A CLIMO CHANCE POP ON MON... WITH LOWER THAN USUAL CONFIDENCE
AS CONVECTION WILL GREATLY DEPEND ON WHETHER THE FRONT HOLDS UP
ACROSS NC OR SHIFTS TO OUR SOUTH. -GIH
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 120 PM MONDAY...
VFR CONDITIONS WILL CONTINUE ACROSS MUCH OF CENTRAL NC THROUGH
TUESDAY NIGHT. THE EXCEPTION WILL BE A GOOD PROBABILITY OF EARLY
STRATUS AND FOG (AND ASSOCIATED IFR/LIFR CONDITIONS)OCCURRING NEAR
KRWI...KFAY AND POTENTIALLY NEAR KRDU. THE FOG/STRATUS WILL BE MOST
LIKELY BETWEEN 09Z-12Z.
ANY CONVECTION THIS AFTERNOON WILL BE LIMITED TO THE SEABREEZE WHICH
MAY TRIGGER AN ISOLATED THUNDERSTORM NEAR OR SOUTH OF KGSB AND KRWI
AND TO THE EAST-SE OF KFAY. THE SAME STORY WILL HOLD FOR TUESDAY
AFTERNOON THOUGH AN ISOLATED THUNDERSTORM MAY OCCUR IN VICINITY OF
KINT AND KGSO LATE IN THE DAY INTO THE EVENING HOURS.
THE WEATHER PATTERN MAY BECOME A LITTLE MORE UNSETTLED WEDNESDAY AS
A WEAK SURFACE BOUNDARY WILL DRIFT INTO CENTRAL NC. THIS FEATURE
WILL SERVE AS A FOCUS FOR THE DEVELOPMENT OF SHOWERS AND
THUNDERSTORMS...MAINLY IN THE AFTERNOON-EVENING HOURS. THIS BOUNDARY
IS PROJECTED TO WEAKEN THURSDAY WHILE HIGH PRESSURE WILL BUILD BACK
INTO THE REGION FRIDAY AND SATURDAY. OTHERWISE...THE OCCURRENCE OF
EARLY MORNING FOG/STRATUS WILL CONTINUE THROUGH THE PERIOD.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...WSS/HARTFIELD
LONG TERM...HARTFIELD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1256 PM EDT MON SEP 1 2014
.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL EXTEND OVER THE AREA THROUGH TUESDAY. A
WEAK COLD FRONT WILL APPROACH THE AREA FROM THE NORTH
WEDNESDAY...THEN STALL AND DISSIPATE THURSDAY AND FRIDAY. HIGH
PRESSURE RIDGES INTO THE REGION FROM OFFSHORE FRIDAY AND
SATURDAY...THEN ANOTHER COLD FRONT WILL DROP INTO THE AREA LATE IN
THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1230 PM MONDAY...MADE MINOR ADJUSTMENTS TO NEAR TERM WX/POP
GRIDS. WITH THE LATEST MOS GUIDANCE AND HRRR MODEL HAVE DECREASED
POPS MAINLY ACROSS THE COASTAL PLAINS. SHOULD STILL SEE SHOWERS
AND THUNDERSTORMS TO DEVELOP ALONG THE SEA BREEZE LATER THIS
AFTERNOON. HIGHS ARE EXPECT TO BE IN THE LOW 90S INLAND TO MID 80S
TO AROUND 90 NEAR THE COAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
AS OF 330 AM MONDAY...WEAK SHRT WV MOVING ACROSS SUPPORTS ISOLD TSTM
THREAT ALONG AND E OF HWY 17 OVERNIGHT...OTHERWISE A REPEAT OF WARM
AND MUGGY CONDITIONS OF PAST FEW NIGHTS. MIN TEMPS FROM MID 70S
INLAND TO NEAR 80 COAST.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 345 AM MON...THE UPPER RIDGE FLATTENS TUES INTO WED AS A
STRONGER SHORTWAVE MOVES ACROSS THE OHIO RIVER VALLEY AND THROUGH
NEW ENGLAND. MAINLY ISOL CONVECTION TUES WITH LIMITED FORCING BUT
BETTER CHANCES WED AFTERNOON THROUGH THURS AS A BACKDOOR COLD FRONT
DROPS INTO AND STALLS ACROSS THE AREA. UPPER LEVEL DYNAMICS REMAIN
RATHER WEAK WITH THE CORE OF THE UPPER JET REMAINING WELL NORTH OF
THE REGION BUT PLENTY OF MOISTURE WILL BE IN PLACE WITH MODERATE TO
STRONG INSTABILITY TO ALLOW FOR SCT SHOWERS AND THUNDERSTORMS...
ESPECIALLY INVOF THE FRONT WHERE BETTER SFC CONVERGENCE WILL RESIDE.
SHEAR AND MID LEVEL LAPSE RATES REMAIN RATHER WEAK SO SEVERE CHANCES
WILL REMAIN LOW BUT COULD SEE LOCALLY HEAVY PRECIP WITH WEAK
STEERING FLOW AND HIGH PWATS.
THE FRONTAL BOUNDARY DISSIPATES LATE THURS INTO FRI WITH HIGH PRES
STRENGTHENING OFFSHORE AND UPPER RIDGING BUILDING ALOFT AND EXPECT
MAINLY ISOLATED DIURNALLY DRIVEN CONVECTION FRI INTO SAT. THE UPPER
RIDGE IS SUPPRESSED AGAIN LATE IN THE WEEKEND WITH ANOTHER SHORTWAVE
TRAVERSING ACROSS THE GREAT LAKES INTO NEW ENGLAND WITH THE
ATTENDANT BACKDOOR COLD FRONT MOVING INTO THE REGION SUN BRINGING
BETTER CHANCES OF SHOWERS AND THUNDERSTORMS.
LOW LEVEL THICKNESSES SUPPORT HIGHS IN THE LOW TO MID 90S THROUGH
MUCH OF THE EXTENDED WHICH IS ABOUT 5 TO AS MUCH AS 10 DEGREES ABOVE
CLIMO. WARMEST DAYS LOOK TO BE TUES AND WED WHEN LOW LEVEL
THICKNESSES ARE GREATEST. SLIGHT COOLING THURS WITH GREATER CLOUD
COVER...ESPECIALLY NORTHERN AREA WHERE NE/ELY FLOW EXPECTED NORTH OF
THE BACKDOOR COLD FRONT...HOWEVER WINDS EXPECTED TO BE RATHER LIGHT.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
SHORT TERM /THROUGH 12Z TUESDAY/...
AS OF 1 PM MON...VFR CONDITIONS WILL DOMINATE MOST OF THE TAF PERIOD
UNDER HIGH PRESSURE. ISOLATED SHOWERS/THUNDERSTORMS MAY DEVELOP
THIS AFTERNOON MAINLY AFFECTING THE COASTAL TAF SITES (EWN/OAJ).
MAY AGAIN SEE SOME PATCHY FOG/STRATUS CONDITIONS LATE TONIGHT INTO
THE EARLY MORNING HOURS...BRINGING CONDITIONS TO MVFR FOR ALL TAF
SITES EXCEPT EWN. ANY FOG/STRATUS WILL START TO MIX OUT AFTER
SUNRISE...BRING CONDITIONS BACK TO VFR.
LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM MON...GENERALLY VFR CONDITIONS EXPECTED THROUGH THE
LONG TERM ALTHOUGH PATCHY LIGHT FOG POSSIBLE DURING THE EARLY
MORNING HOURS. ISOL-SCT CONVECTION POSSIBLE EACH DAY WITH BEST
CHANCES WED THROUGH THURS AS A BACKDOOR FRONT DROPS INTO THE REGION.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 1230 PM MON...NO CHANGES TO FORECAST. THE LATEST BUOY OBS
ARE SHOWING SW WINDS 5 TO 15 KTS WITH SEAS 2 TO 3 FEET. SW WINDS
WILL CONTINUE UNDER THE PERSIST BERMUDA HIGH AND INLAND TROF
PATTERN THROUGH THE PERIOD. SPEEDS WILL DIMINISH TO 10-15 KT THIS
MORNING...THEN INCREASE TO 15-20 KT LATE AFTN INTO THIS
EVENING...DIMINISHING AGAIN LATE TONIGHT.
WW3 INITIALIZED BETTER WITH SEAS MAINLY AROUND 3 FT...AND ADJUSTED
FCST ACCORDINGLY. HEIGHTS BUILDING TO AROUND 4 FT OUTER PORTIONS OF
CENTRAL AND NRN WATERS THIS AFTN AND EVENING.
LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM MON...THE BERMUDA HIGH OFFSHORE WILL BRING S/SW WINDS
ACROSS THE WATERS INTO WED. WINDS GENERALLY AROUND 5-15 KT DURING
LATE NIGHT AND MORNING HOURS BUT GRADIENTS TIGHTEN DURING THE
AFTERNOON AND EVENING HOURS BOTH MON AND TUES AS THE PIEDMONT
THERMAL TROUGH STRENGTHENS ALLOWING WINDS TO INCREASE TO AROUND
10-20 KT. A BACKDOOR FRONT DROPS INTO THE REGION WED THROUGH THURS
BRINGING LIGHT WINDS...GENERALLY LESS THAN 10 KT. WINDS NORTH OF THE
FRONT EXPECTED TO BE E TO NE WHILE REMAINING S/SW TO THE SOUTH. THE
FRONT IS PROGGED TO DISSIPATE BY FRI WITH SLY FLOW AROUND 5-10
RETURNING TO ALL WATERS. MODELS IN GOOD AGREEMENT KEEPING SEAS
AROUND 2-4 FT...LOCALLY TO 5 FT NEAR DIAMOND SHOALS...INTO EARLY WED
BUT THEN SUBSIDE TO AROUND 2 FT THURS AND FRI WITH LIGHT WINDS
ACROSS THE WATERS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JBM
NEAR TERM...JBM/BM
SHORT TERM...JBM
LONG TERM...SK
AVIATION...JBM/SK/BM
MARINE...JBM/SK/BM
AREA FORECAST DISCUSSION
NWS TULSA OK
329 PM CDT MON SEP 1 2014
.DISCUSSION...
A PROGRESSIVE...LOW AMPLITUDE SHORTWAVE TROUGH IS SLIDING EAST
ACROSS THE NORTH CENTRAL PART OF THE COUNTRY TODAY. A PAIR OF
EMBEDDED VORTICITY MAXIMA EXIST...ONE LIFTING QUICKLY NORTHEAST
INTO THE GREAT LAKES...AND ANOTHER MOVING ACROSS WY ATTM.
NORTHEAST OK/NORTHWEST AR LIES ON THE SOUTHERN FRINGE OF THE
DECENT WESTERLY FLOW IN THE MID LEVELS. AT THE SURFACE...A MORE
COMPLEX PATTERN EXISTS DUE TO OVERNIGHT CONVECTION THAT WAS MORE
EXTENSIVE THAN FORECAST. THE OUTFLOW BOUNDARY FROM THAT CONVECTION
HAS BEEN RETREATING NORTH DURING THE AFTERNOON AND IS
APPROACHING THE KANSAS BORDER. MEANWHILE...THE SYNOPTIC COLD FRONT
HAS BECOME NEARLY STATIONARY ACROSS CENTRAL AND SW KS. THE HRRR
HAS BEEN CONSISTENT ALL DAY IN DVLPNG STORMS BTWN 22-00Z IN THE
ZONE BTWN THE TWO BOUNDARIES. DIRECTIONAL/SPEED SHEAR SHOULD BE
GREAT ENOUGH TO SUPPORT SUPERCELLS...ESPECIALLY GIVEN AVAILABLE
CAPE. LOW LEVEL BACKED WINDS IN BTWN THE TWO BOUNDARIES
SUGGESTS...IF A SUPERCELL CAN GET GOING...THAT A LARGE HAIL/TORNADO
RISK EXISTS BEFORE CELLS GRADUALLY CONGEAL INTO CLUSTERS AND THEN
MOVE E/SE THIS EVENING...WHEN THE MAIN THREAT BECOMES DAMAGING
WINDS. MORE DEVELOPMENT IS FORECAST BY THE HRRR LATER TONIGHT
NORTH OF THE EFFECTIVE BOUNDARY. THERE WILL BE A SHARP CUTOFF AS
YOU GO SOUTH WHERE RAIN FALLS AND WHERE IT DOESN`T...GIVEN STRONG
CAP IN PLACE DUE TO EML.
I BACKED OFF SOME ON LOWS TONIGHT ACROSS THE NE OK AND NW AR GIVEN
POTENTIAL FOR CONVECTIVELY COOLED OUTFLOW...MUCH LIKE LAST NIGHT.
RAIN/STORM CHANCES WILL CONTINUE INTO TUESDAY MAINLY ACROSS NE
OK/NW AR NEAR AND NORTH OF THE EFFECTIVE BOUNDARY...WHICH WILL
BEGIN TO RETREAT AGAIN TOMORROW AND ESPECIALLY TOMORROW NIGHT. THE
BEST CHANCES FOR RAIN/STORMS TUESDAY NIGHT WILL BE NORTH AND EAST
OF TULSA IN THE WARM ADVECTION REGIME. PRECIP CHANCES COME TO AN
END WEDNESDAY AS THE BOUNDARY LIFTS NORTH OF THE REGION AND MID
LEVEL HEIGHTS RISE. GUSTY SOUTHWEST WINDS WILL PUSH TEMPS BACK
INTO THE UPPER 90S WEDNESDAY AFTERNOON ACROSS NE OK.
THE DETERMINISTIC RUNS OF THE GFS/ECMWF TODAY ARE SLOWER WITH THE
FRONT TOWARD THE END OF THE WEEK...GFS MORE SO THAN THE ECMWF.
NEVERTHELESS...POPS WILL BE CARRIED FRIDAY AND
SATURDAY...GRADUALLY TAPERING OFF SUNDAY. TEMPS WILL FALL BACK
INTO THE 80S FOR HIGHS AND 60S FOR LOWS.
THE RATHER ACTIVE PATTERN ACROSS THE NORTHERN TIER OF STATES
CONTINUES INTO NEXT WEEK...AS ANOTHER STRONG SYSTEM MOVES ACROSS
THE NORTHERN PART OF THE COUNTRY. AN EVEN STRONGER FRONT COULD BE
ON THE WAY IN ABOUT 10 DAYS...A SIGN OF THE CHANGE IN SEASONS.
LACY
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 71 91 75 96 / 60 40 20 10
FSM 75 91 73 94 / 30 40 20 10
MLC 77 93 76 93 / 30 30 10 10
BVO 69 90 69 96 / 60 40 30 10
FYV 71 86 69 91 / 60 50 30 20
BYV 71 86 69 91 / 60 50 30 20
MKO 73 90 72 93 / 50 40 20 10
MIO 71 88 72 94 / 60 40 40 10
F10 74 92 74 93 / 40 30 20 10
HHW 75 94 74 95 / 10 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
LONG TERM....30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
343 PM EDT MON SEP 1 2014
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE INTO TUESDAY UNTIL A COLD
FRONTAL PASSAGE BRINGS DRIER AND SLIGHTLY COOLER AIR TO CENTRAL
PENNSYLVANIA THROUGH MID WEEK. HUMIDITY WILL RETURN TOWARD THE
END OF THE WEEK AHEAD OF THE NEXT FRONTAL SYSTEM THAT WILL BRING
THE CHANCE OF RAIN FOR THE UPCOMING WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
18Z...RADAR LOOP INDICATES CONVECTIVE PCPN IS STARTING TO INCREASE
IN CVRG OVER THE LAST 30 MINUTES OVER THE SRN 1/3 OF THE CWA WHERE
THE RAP SHOWS THE HIGHEST CAPE IN PA. EVEN BETTER INSTABILITY CAN
BE FOUND SOUTH OF THE MASON DIXON LINE NEAR THE I95 CORRIDOR WHERE
THE FIRST LTG STRIKE OF THE AFTN HAS BEEN DETECTED. HIGHEST POPS
/30-40%/ HAVE BEEN PAINTED OVER THE SRN TIER ZONES THRU THE EARLY
EVENING HOURS. FURTHER TO THE NORTH...WEAK LG SCALE FORCING
COUPLED WITH MARGINAL INSTABILITY /HINDERED BY CLOUD COVER/ AND
VERY MOIST/HUMID AIRMASS CONTINUES TO SUPPORT IDEA OF MAINLY ISOLD
SHOWERS. MESO MDL GUIDANCE SHOWS EVE STORMS EVENTUALLY DISSIPATING
AFTER DARK WITH THE LOSS OF HEATING. UPSTREAM STORMS OVER THE GRT
LWR MI/OH VLY SHOULD ALSO EXHIBIT A CONSIDERABLE WEAKENING TREND
AS THE EVOLVE EWD AND MAY SURVIVE INTO WRN PA LATE TNGT.
MAIN FOCUS WILL SHIFT TO THE WEST TONIGHT AS A WELL-DEFINED COLD
FRONT APPROACHES THE AREA FROM THE N/W. HIGHEST POPS /40-50%/
WILL BE OVER THE FAR NW MTNS BASED ON MULTI-MODEL ENSEMBLE CONSENSUS
QPF. IT WILL BE MUGGY WITH LOWS 65-70F. LGT WINDS AND HI DEWPOINTS
ALONG WITH SOME PARTIAL CLEARING FAVORS SOME LOW CLOUDS/FOG.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
A RELATIVELY LOW AMPLITUDE SHORTWAVE TROUGH WILL SLIDE EWD FROM
THE GREAT LAKES/MIDWEST INTO NRN NEW ENGLAND BY THE END OF THE
PERIOD. THIS FEATURE WILL DRIVE A WELL-DEFINED COLD FRONT /WITH
SHARP MSTR-PW GRADIENT/ SEWD FROM THE LWR LKS/OH VLY ACRS THE
N-CNTRL APPALACHIANS. A CONDITIONAL RISK FOR STRONG TO ISOLATED
SEVERE STORMS WILL EXIST FROM LATE TUE MORNING THROUGH THE
AFTERNOON WITH THE PRIMARY POTNL TSTM HAZARD BEING DAMAGING
WINDS.
CLOUD COVER FROM UPSTREAM CONVECTION LKLY ONGOING AT 12Z ALONG
WITH RESIDUAL OVERNIGHT LOW STRATUS/FOG SHOULD ACT TO LIMIT
DESTABILIZATION EARLY TOMORROW. ALTHOUGH 700-500MB LAPSE RATES
WILL GENERALLY REMAIN WEAK TO POOR...THE MODELS SHOW A BELT OF
STRONGER WESTERLY MID-LVL FLOW AND DEEP LYR SHEAR. THIS SHOULD
HELP TO SUPPORT AN INCREASE IN CONVECTIVE PCPN/INTENSITY AS
RENEWED DEVELOPMENT OCCURS ALONG OUTFLOWS/DIFFERENTIAL HEATING
ZONES BY LATE MORNING INTO THE AFTERNOON...WITH SOME ORGANIZATION
INTO LINE SEGMENTS/CLUSTERS. THIS SHOULD YIELD AT LEAST AN ISOLD
DMGG WIND THREAT...WARRANTING AN UPGRADE BY SPC TO A CATEGORICAL
/SLGT/ RISK DESIGNATION. THIS HAS BEEN REFLECTED IN AN UPDATED
HWO.
EARLY CLOUDS SHOULD BREAK FOR A WARM AND HUMID DAY WITH FCST
HIGHS EXPECTED TO RANGE FROM THE MID 70S OVER THE NW TO NEAR 90
OVER THE LOWER SUSQ VLY. THE SECOND HALF OF THE PERIOD ESPECIALLY
AFTER MIDNIGHT SHOULD FEATURE A COOLER/DRYING TREND BEHIND THE
FRONT WITH PWS FALLING AOB NORMAL BY 12Z WED.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
COLD FRONT EXITING TO THE EAST TUE NIGHT ALONG WITH NORTHWEST
FLOW AROUND BUILDING HIGH PRESSURE AREA OVER OHIO VALLEY WILL
BRING A TRANSITION TO A NOTICABLY DRIER AIRMASS FOR MIDWEEK.
DAYTIME HIGHS WILL REMAIN SLIGHTLY ABOVE NORMAL...BUT LOWER
DEWPOINTS WILL MAKE IT FEEL MORE COMFORTABLE. OVERNIGHT LOWS WED
NIGHT WILL DIP TO NEAR 50F IN THE NORTHERN MTNS TO AROUND 60F IN
THE SE.
THE HIGH WILL MOVE OFF THE EAST COAST THU INTO FRI...ALLOWING MORE
HUMID AIR TO BEGIN RETURNING TO THE REGION. A SURFACE LOW SLIDES
FROM THE NORTHERN PLAINS ACROSS THE GREAT LAKES AND LIFTING INTO
S CANADA ON FRI...DRAGGING A COLD FRONT ALONG BEHIND. AS THIS
FRONT APPROACHES...AN AREA OF HIGHER PWATS /1-2"/ SURGES INTO THE
OHIO VALLEY...AND THEN INTO PA FRI NIGHT INTO SAT. AT SAME TIME A
BROAD UPPER TROUGH SAGS SOUTHWARD. THIS WILL BRING ELEVATED
CHANCES FOR SHOWERS/TSTMS STARTING FRI NIGHT IN THE NW AND
SPREADING AREAWIDE ON SAT.
BEHIND THE FRONT...AIRMASS CHANGE WILL USHER IN MUCH COOLER AND
DRIER AIR FOR LATE WEEKEND INTO EARLY NEXT WEEK. HIGHS WILL FALL
BACK ABOUT 10F...RANGING FROM THE UPPER 60S TO MID 70S. AS LARGE
HIGH PRESSURE AREA TRACKS ACROSS NEW ENGLAND...MORNING LOWS SHOULD
DIP WELL INTO THE 40S ACROSS THE NORTHERN MTNS...AND IN THE LOWER
TO MID 50S ACROSS THE SOUTH.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
18Z...CIGS/VISBYS HAVE IMPROVED TO VFR OR MVFR AS EXPECTED.
HOWEVER DESPITE A GENERAL INCREASE IN SHOWER ACTIVITY THERE IS
STILL LOW CONFIDENCE IN POINT TERMINAL IMPACTS. EVOLUTION OF
CONVECTIVE ACTIVITY AND COLLOCATION OF BEST INSTABILITY SUGGESTS
THE SRN TAFS HAVE THE BEST CHC TO SEE SCT SHOWERS OR A BRIEF TSRA
DOWNPOUR. HAVE ADDED SOME 1HR TEMPS THRU 19Z WITH SHOWERS MOVG
THRU AOO/UNV.
OTHER CONCERN WILL BE CLOUD TRENDS OVERNIGHT WITH MOIST AIRMASS
LKLY PROMOTING ANOTHER PERIOD OF LOW CIGS/FOG INTO TUE MORNING. A
COLD FRONT MOVG EWD THRU THE MIDWEST WILL ALSO BRING THE CHC FOR
SOME SHOWERS TO REACH THE NW 1/4 TO 1/3 OF THE AIRSPACE BY
EARLY TUE MORNING. THIS FRONT WILL BE A FOCUS FOR SCT-NMRS
SHWRS/TSTMS TUES AFTN-EVE AS IT MOVES SEWD ACRS CENTRAL PA. THE
RECENT GUIDANCE SUGGESTS A SLIGHTLY HIGHER PROBABILITY FOR LCL
SVR STORMS AND AT LEAST AN ISOLD THREAT FOR DAMAGING TSTM WIND
GUSTS.
OUTLOOK...
WED-THU...PATCHY AM FOG...OTHERWISE VFR.
FRI...MAINLY VFR. CHC OF PM TSTMS WEST.
SAT...VFR/MVFR WITH SCT SHWRS/TSTMS ASSOCD WITH COLD FROPA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
249 PM EDT MON SEP 1 2014
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE INTO TUESDAY UNTIL A COLD
FRONTAL PASSAGE BRINGS DRIER AND SLIGHTLY COOLER AIR TO CENTRAL
PENNSYLVANIA THROUGH MID WEEK. HUMIDITY WILL RETURN TOWARD THE
END OF THE WEEK AHEAD OF THE NEXT FRONTAL SYSTEM THAT WILL BRING
THE CHANCE OF RAIN FOR THE UPCOMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z...RADAR LOOP INDICATES CONVECTIVE PCPN IS STARTING TO INCREASE
IN CVRG OVER THE LAST 30 MINUTES OVER THE SRN 1/3 OF THE CWA WHERE
THE RAP SHOWS THE HIGHEST CAPE IN PA. EVEN BETTER INSTABILITY CAN
BE FOUND SOUTH OF THE MASON DIXON LINE NEAR THE I95 CORRIDOR WHERE
THE FIRST LTG STRIKE OF THE AFTN HAS BEEN DETECTED. HIGHEST POPS
/30-40%/ HAVE BEEN PAINTED OVER THE SRN TIER ZONES THRU THE EARLY
EVENING HOURS. FURTHER TO THE NORTH...WEAK LG SCALE FORCING
COUPLED WITH MARGINAL INSTABILITY /HINDERED BY CLOUD COVER/ AND
VERY MOIST/HUMID AIRMASS CONTINUES TO SUPPORT IDEA OF MAINLY ISOLD
SHOWERS. MESO MDL GUIDANCE SHOWS EVE STORMS EVENTUALLY DISSIPATING
AFTER DARK WITH THE LOSS OF HEATING. UPSTREAM STORMS OVER THE GRT
LWR MI/OH VLY SHOULD ALSO EXHIBIT A CONSIDERABLE WEAKENING TREND
AS THE EVOLVE EWD AND MAY SURVIVE INTO WRN PA LATE TNGT.
MAIN FOCUS WILL SHIFT TO THE WEST TONIGHT AS A WELL-DEFINED COLD
FRONT APPROACHES THE AREA FROM THE N/W. HIGHEST POPS /40-50%/
WILL BE OVER THE FAR NW MTNS BASED ON MULTI-MODEL ENSEMBLE CONSENSUS
QPF. IT WILL BE MUGGY WITH LOWS 65-70F. LGT WINDS AND HI DEWPOINTS
ALONG WITH SOME PARTIAL CLEARING FAVORS SOME LOW CLOUDS/FOG.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
A RELATIVELY LOW AMPLITUDE SHORTWAVE TROUGH WILL SLIDE EWD FROM
THE GREAT LAKES/MIDWEST INTO NRN NEW ENGLAND BY THE END OF THE
PERIOD. THIS FEATURE WILL DRIVE A WELL-DEFINED COLD FRONT /WITH
SHARP MSTR-PW GRADIENT/ SEWD FROM THE LWR LKS/OH VLY ACRS THE
N-CNTRL APPALACHIANS. A CONDITIONAL RISK FOR STRONG TO ISOLATED
SEVERE STORMS WILL EXIST FROM LATE TUE MORNING THROUGH THE
AFTERNOON WITH THE PRIMARY POTNL TSTM HAZARD BEING DAMAGING
WINDS.
CLOUD COVER FROM UPSTREAM CONVECTION LKLY ONGOING AT 12Z ALONG
WITH RESIDUAL OVERNIGHT LOW STRATUS/FOG SHOULD ACT TO LIMIT
DESTABILIZATION EARLY TOMORROW. ALTHOUGH 700-500MB LAPSE RATES
WILL GENERALLY REMAIN WEAK TO POOR...THE MODELS SHOW A BELT OF
STRONGER WESTERLY MID-LVL FLOW AND DEEP LYR SHEAR. THIS SHOULD
HELP TO SUPPORT AN INCREASE IN CONVECTIVE PCPN/INTENSITY AS
RENEWED DEVELOPMENT OCCURS ALONG OUTFLOWS/DIFFERENTIAL HEATING
ZONES BY LATE MORNING INTO THE AFTERNOON...WITH SOME ORGANIZATION
INTO LINE SEGMENTS/CLUSTERS. THIS SHOULD YIELD AT LEAST AN ISOLD
DMGG WIND THREAT...WARRANTING AN UPGRADE BY SPC TO A CATEGORICAL
/SLGT/ RISK DESIGNATION. THIS HAS BEEN REFLECTED IN AN UPDATED
HWO.
EARLY CLOUDS SHOULD BREAK FOR A WARM AND HUMID DAY WITH FCST
HIGHS EXPECTED TO RANGE FROM THE MID 70S OVER THE NW TO NEAR 90
OVER THE LOWER SUSQ VLY. THE SECOND HALF OF THE PERIOD ESPECIALLY
AFTER MIDNIGHT SHOULD FEATURE A COOLER/DRYING TREND BEHIND THE
FRONT WITH PWS FALLING AOB NORMAL BY 12Z WED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE WILL BUILD IN FOR MIDWEEK...BRINGING AT LEAST A
COUPLE OF DAYS OF MILD AND LESS HUMID WEATHER. THE HIGH SHOULD
MOVE OFF THE EAST COAST LATE IN THE WEEK ALLOWING A RETURN FLOW OF
MORE HUMID AIR INTO THE REGION...ALONG WITH THE CHANCE OF SOME
MAINLY DIURNAL CONVECTION STARTING FRIDAY.
GUIDANCE IS IN PRETTY GOOD AGREEMENT DRAGGING A COLD FRONT THROUGH
THE AREA FRIDAY NIGHT AND SATURDAY...ACCOMPANIED BY MORE SHOWERS
AND THUNDERSTORMS.
THE UPCOMING WEEK WILL BE ONE OF THE RARE EXTENDED PERIODS OF
WARMER THAN NORMAL TEMPERATURES WE HAVE SEEN THIS SUMMER. HIGH
TEMPERATURES WILL CLIMB TO ALMOST 90 ACROSS THE SOUTH AND EAST ON
TUESDAY AHEAD OF THE FRONTAL PASSAGE. THEN THE UPPER RIDGE WILL
REBOUND OVER THE EASTERN US FOR THE SECOND HALF OF THE
WEEK...KEEPING HIGH TEMPERATURES AT OR SLIGHTLY ABOVE SEASONAL
NORMALS FOR EARLY SEPTEMBER.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
18Z...CIGS/VISBYS HAVE IMPROVED TO VFR OR MVFR AS EXPECTED.
HOWEVER DESPITE A GENERAL INCREASE IN SHOWER ACTIVITY THERE IS
STILL LOW CONFIDENCE IN POINT TERMINAL IMPACTS. EVOLUTION OF
CONVECTIVE ACTIVITY AND COLLOCATION OF BEST INSTABILITY SUGGESTS
THE SRN TAFS HAVE THE BEST CHC TO SEE SCT SHOWERS OR A BRIEF TSRA
DOWNPOUR. HAVE ADDED SOME 1HR TEMPS THRU 19Z WITH SHOWERS MOVG
THRU AOO/UNV.
OTHER CONCERN WILL BE CLOUD TRENDS OVERNIGHT WITH MOIST AIRMASS
LKLY PROMOTING ANOTHER PERIOD OF LOW CIGS/FOG INTO TUE MORNING. A
COLD FRONT MOVG EWD THRU THE MIDWEST WILL ALSO BRING THE CHC FOR
SOME SHOWERS TO REACH THE NW 1/4 TO 1/3 OF THE AIRSPACE BY
EARLY TUE MORNING. THIS FRONT WILL BE A FOCUS FOR SCT-NMRS
SHWRS/TSTMS TUES AFTN-EVE AS IT MOVES SEWD ACRS CENTRAL PA. THE
RECENT GUIDANCE SUGGESTS A SLIGHTLY HIGHER PROBABILITY FOR LCL
SVR STORMS AND AT LEAST AN ISOLD THREAT FOR DAMAGING TSTM WIND
GUSTS.
OUTLOOK...
WED-THU...PATCHY AM FOG...OTHERWISE VFR.
FRI...MAINLY VFR. CHC OF PM TSTMS WEST.
SAT...VFR/MVFR WITH SCT SHWRS/TSTMS ASSOCD WITH COLD FROPA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...LA CORTE
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1239 PM CDT MON SEP 1 2014
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 308 AM CDT MON SEP 1 2014
WATER VAPOR SATELLITE LOOP COUPLED WITH RAP ANALYSIS SHOWS VIGOROUS
MID-LEVEL TROUGH ROTATING THROUGH THE PLAINS TOWARD THE UPPER
MISSISSIPPI RIVER VALLEY. AT THE SURFACE 999MB LOWS WAS OVER WESTERN
ONTARIO WITH A COLD FRONT EXTENDING SOUTHWARD THROUGH MN/NW
IA/CENTRAL NEB. RADAR WAS LIT UP WITH SHOWERS/THUNDERSTORMS ACROSS
EASTERN MN INTO THE FORECAST AREA AHEAD OF THE MID-LEVEL WAVE AND
SURFACE COLD FRONT. OTHERWISE...TEMPERATURES ACROSS THE AREA EARLY
THIS MORNING WERE IN THE 60S.
LOOK FOR THE SURFACE COLD FRONT AND ASSOCIATED CONVECTION TO
CONTINUE PUSHING EAST ACROSS THE AREA THIS MORNING WITH THE BULK OF
THE RAIN EXITING EAST BY LATE MORNING. KEPT LINGERING AND
DIMINISHING CHANCES GOING HOWEVER INTO THE AFTERNOON AS THE MID-
LEVEL TROUGH/COLD AIR ALOFT POSSIBLY POPPING A FEW INSTABILITY
SHOWERS AND THUNDERSTORMS. NOT EXPECTING ANY SEVERE THREAT AS BEST
CAPE AND WIND SHEAR SHIFT EAST/SOUTHEAST OF THE AREA.
FOR TONIGHT...WILL SEE ANOTHER WEAK MID-LEVEL WAVE ROTATE TOWARD THE
AREA FROM THE NORTHERN PLAINS. NAM SHOWING A DECENT SHOT OF 700-
300MB PVA MOVING IN MAINLY WEST OF THE MISSISSIPPI RIVER AFTER
MIDNIGHT WITH BUFKIT SHOWING INSTABILITY/MOISTURE MAINLY CONFINED
ABOVE 800MB. KEPT A SMALL-END CHANCE OF SHOWERS/ISOLATED WEST OF THE
MISSISSIPPI AFTER MIDNIGHT BASED ON THIS SIGNAL. OVERNIGHT LOWS ARE
EXPECTED TO FALL INTO THE 50S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 308 AM CDT MON SEP 1 2014
A SMALL CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO
TUESDAY MAINLY NORTH OF I-94 AS THE WEAK MID-LEVEL TROUGH ROTATES
ACROSS THE FORECAST AREA. PLAN ON HIGHS RANGING FROM THE MIDDLE 70S
ACROSS NORTH CENTRAL WI...TO THE UPPER 70S/LOWER 80S ELSEWHERE.
SURFACE CYCLOGENESIS OVER THE NORTHERN PLAINS WILL PUSH A WARM FRONT
TOWARD THE AREA WEDNESDAY/WEDNESDAY NIGHT. ALL MODELS SHOW
INCREASING 850MB MOISTURE TRANSPORT/WARM AIR ADVECTION NOSING INTO
THE AREA WITH THE FRONT FOR INCREASING COVERAGE OF THUNDERSTORMS.
PRECIPITABLE WATER VALUES PUSHING 1.9 INCHES BY THURSDAY MORNING WITH
WARM CLOUD DEPTH LAYERS INCREASING INTO THE 4-4.5KM RANGE. BASED ON
THIS SIGNAL...WILL HAVE TO WATCH FOR A HEAVY RAINFALL POTENTIAL
ALONG WITH OTHER SEVERE THREATS AS WELL AS CAPE AND BULK SHEAR
INCREASE ALONG THE WARM FRONT. AT THIS POINT...MODELS SHOWING HIGHER
SEVERE POTENTIAL STAYING WEST OF THE MISSISSIPPI RIVER IN MORE
FAVORABLE CAPE/SHEAR ENVIRONMENT. WILL HAVE TO KEEP A CLOSE ON THIS
OVER THE NEXT COUPLE DAYS. LOOK FOR HIGHS ON WEDNESDAY TO TOP OFF IN
THE UPPER 70S TO MIDDLE 80S WITH DEW POINTS CREEPING UP INTO THE 65-
70 DEGREE RANGE.
THUNDERSTORM CHANCES CONTINUE THURSDAY INTO THURSDAY NIGHT AS THE
LOW PULLS NORTHEAST INTO ONTARIO CANADA...PUSHING A COLD FRONT
THROUGH THE AREA. THURSDAY WILL HAVE TO BE WATCHED CLOSELY AS WELL
FOR SEVERE POTENTIAL AS THE GFS IS SHOWING 0-6KM BULK SHEAR OF 30-
50KT COUPLED WITH MUCAPE POOL OF 2500-4500J/KG. HIGHS ON THURSDAY
AHEAD OF THE COLD FRONT ARE EXPECTED TO TOP OFF WELL INTO THE 80S
WITH DEW POINTS IN THE 70-75 DEGREE RANGE.
DRIER/COOLER AIR FILTERS INTO THE AREA FRIDAY AND INTO THE WEEKEND
AS CANADIAN HIGH PRESSURE BUILD INTO THE REGION. PLAN ON
TEMPERATURES BY THIS WEEKEND TO FEEL A BIT MORE LIKE FALL WITH HIGHS
IN THE 60S/LOWER 70S AND LOWS IN THE 50S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1239 PM CDT MON SEP 1 2014
MAIN AVIATION FORECAST CONCERNS IS FOG POTENTIAL IN THE MISSISSIPPI
RIVER VALLEY TONIGHT. LATEST KARX RADAR INDICATES LAST LINE OF
SHOWERS ALONG SURFACE COLD FRONT EXTENDING FROM WESTERN WISCONSIN
INTO NORTHEAST IOWA PER LATEST 17Z SURFACE ANALYSIS. LATEST 17Z
METARS ARE INDICATING CEILING HEIGHTS RISING ABOVE MVFR CONDITIONS
AND BECOMING VFR CONDITIONS AT TAF SITES THIS AFTERNOON. WEAK
SURFACE RIDGE BUILDS INTO NORTHERN IOWA BEHIND COLD FRONT AND ALLOWS
SKIES TO CLEAR WEST TO EAST ACROSS THE AREA THIS AFTERNOON INTO THIS
EVENING. THE 02.12Z NAM BUFKIT SOUNDING SHOWS INVERSION DEVELOPING
AT LSE TAF SITE AND WINDS BECOME LIGHT WITHIN THE LOWEST 500
FEET...HOWEVER BUFKIT SOUNDING SHOW 15 KNOTS JUST ABOVE 500 FEET
PLUS A WEAK IMPULSE PRODUCES A MID LEVEL CLOUD DECK OVER THE REGION.
THIS WOULD INHIBIT ANY FOG DEVELOPMENT IN THE MISSISSIPPI RIVER
VALLEY AND AT LSE TAF SITE. AT THIS TIME...DID NOT INTRODUCE ANY
FOG AT LSE TAF SITE AND LATER SHIFTS WILL HAVE TO MONITOR IF SKIES
REMAIN CLEAR THROUGH THE NIGHT TIME HOURS. VFR CONDITIONS WILL
PREVAIL AT RST TAF SITE THROUGH MUCH OF THE PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...DTJ