Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/12/12
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
502 AM MST MON SEP 10 2012
.UPDATE...UPDATED AVIATION DISCUSSION...
&&
.SYNOPSIS...
A WEAK UPPER LOW WILL INTERACT WITH A MOIST AIRMASS OVER ARIZONA AND
SOUTHEAST CALIFORNIA...LEADING TO ABOVE AVERAGE STORM CHANCES
THROUGH TUESDAY. THERE WILL BE LARGE VARIATIONS IN STORM COVERAGE
AND INTENSITY FROM DAY TO DAY...WITH STORMS LIKELY TODAY AND
TUESDAY OVER SOUTH-CENTRAL ARIZONA. HIGH TEMPERATURES WILL BE BELOW
NORMAL THROUGH THURSDAY. DRY AIR MOVES IN DURING THE LATTER HALF OF
THE WEEK WITH STORM CHANCES ENDING OVER SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA WEDNESDAY...AND OVER SOUTH-CENTRAL ARIZONA BY
FRIDAY. A GRADUAL WARMING TREND WILL ACCOMPANY THE DRIER AIR.
&&
.DISCUSSION...
TODAY THROUGH WEDNESDAY...A BATCH OF SHOWERS AND THUNDERSTORMS
DEVELOPED OVER SANTA CRUZ COUNTY BEFORE MIDNIGHT AND HAS WORKED ITS
WAY INTO NORTHWEST PINAL AND EASTERN MARICOPA COUNTIES...BUT IN A
WEAKENED STATE. THE SHOWERS APPEAR TO BE BE ASSOCIATED WITH A
CIRCULATION EVIDENT IN THE WATER VAPOR IMAGERY CENTERED
SOUTH-SOUTHWEST OF NOGALES. THE RUC PICKED UP ON THIS VORT MAX BUT
DID NOT PLACE THE PRECIP CORRECTLY. THE 00Z NAM AND GFS DIDNT PICK
UP ON IT THOUGH THE 06Z VERSIONS NOW HINT AT SOMETHING.
MEANWHILE...THE UPPER LOW IS CENTERED OVER FAR NORTHERN BAJA. THE
LATEST OPERATIONAL MODELS DEPICT THE MAIN AREAS OF VORTICITY CLOSER
TO THE LOW CENTER AS WOULD BE EXPECTED. THE OMEGA AND UPPER LEVEL
DIVERGENCE FIELDS DIFFER CONSIDERABLY THOUGH WITH THE GFS PRODUCING
ITS TYPICAL SPORADIC BULLSEYES AND ASSOCIATED QPF MAXIMA. AS
USUAL...THERE ARE TREMENDOUS DIFFERENCES IN THE MODEL QPF WITH THE
NAM CHARACTERISTICALLY ON THE LOW SIDE...THOUGH NOT AS LOW AS THE
NMM6KM. THE NAM/GFS/SREF BASED POPS ALL CONTINUE TO DEPICT WELL
ABOVE NORMAL PRECIP CHANCES ACROSS THE FORECAST AREA TODAY AND
TUESDAY AS THE LOW FINALLY TRACKS NORTHEASTWARD. JUST WHERE THE MORE
INTENSE SHOWER/STORM ACTIVITY WILL BE FOR OUR FORECAST AREA IS VERY
DIFFICULT TO FIGURE OUT. THE AREA WHERE STORMS WERE MOST ACTIVE
SUNDAY SHOULD HAVE SOME STABILIZATION OF THE BOUNDARY LAYER TO
OVERCOME...YET BOTH THE NAM AND GFS DEPICT PRECIP FOR THAT AREA
AGAIN TODAY. SOUTH-CENTRAL ARIZONA SHOULD BE LESS STABILIZED FROM
LAST NIGHT BUT THIS MORNINGS SHOWERS MIGHT LEAD TO INHIBITED
DEVELOPMENT LATER ON. THE 00Z LOCAL WRF HAS NOT BEEN RELIABLE OF
LATE AS IT HAS FAILED TO EVEN INITIALIZE SIGNIFICANT CONVECTION. A
MIX OF LOCALLY HEAVY RAIN AND STRONG WINDS WILL BE POSSIBLE ANYWHERE
IN THE FORECAST AREA TODAY...LESS SO OVER PORTIONS OF SOUTHEAST
CALIFORNIA TUESDAY. ON WEDNESDAY...THE LOW WILL BE EAST OF ARIZONA
AND BARELY BE A SHORT WAVE BUT AN UPSTREAM KICKER SHORT WAVE MAY
STILL BE OVER EASTERN PORTIONS OF THE FORECAST AREA. HOWEVER...THERE
WILL BE SIGNIFICANTLY LESS MOISTURE TO WORK WITH AND THUS PRECIP
CHANCES DROP DRAMATICALLY. HIGH TEMPERATURES WILL BE WELL BELOW
NORMAL THROUGH TUESDAY AT MOST LOCATIONS. OVERALL FORECASTS REFLECT
A MULTIMODEL BLEND.
THURSDAY THROUGH SUNDAY...
THE GFS AND ECMWF DIFFER ON WHERE HIGH PRESSURE WILL BE CENTERED
DURING THE LATTER HALF OF THE WEEK. THE GFS HAS IT OVER ARIZONA
WHEREAS THE ECMWF IS FURTHER WEST AND HAS WEAK LINGERING TROUGHING
OVER NEW MEXICO. THE ECMWF IS ALSO SLOWER TO DRY THINGS OUT BUT WITH
A NORTHERLY COMPONENT TO THE FLOW...IT WILL BE DIFFICULT TO HOLD ON
TO ANY MEANINGFUL MOISTURE. EXCEPT FOR A SLIGHT CHANCE OVER FAR
EASTERN PORTIONS OF THE FORECAST AREA THURSDAY...EXPECT DRY
CONDITIONS THROUGH SUNDAY. MEANWHILE...TEMPS WILL SLOWLY WARM UP BUT
IT DOES NOT APPEAR THAT THEY WILL GET MUCH ABOVE NORMAL.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
ALREADY LOOKING AT SOME EARLY MORNING SHOWERS ACROSS THE AREA. THESE
WILL PERSIST UNTIL AROUND 15Z...WITH IMPROVING CONDITIONS EXPECTED
INTO EARLY AFTERNOON. STORMS ARE EXPECTED TO INITIATE AROUND THE
PHOENIX AREA BY MID AFTERNOON AND WHILE TIMING IS ALWAYS AN
ISSUE...I INTRODUCED VCTS AT ALL PHOENIX SITES FROM 21Z TIL MID
EVENING. STORMS SHOULD DISSIPATE GRADUALLY INTO THE EVENING HOURS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
ATMOSPHERE PRETTY WORKED OVER FROM YESTERDAYS CONVECTION AND I
THINK STORM COVERAGE WILL BE SOMEWHAT LIMITED TODAY.
NONETHELESS...SCATTERED SHOWERS ARE EXPECTED FROM MID AFTERNOON
ONWARD WITH THE BEST CHANCES AROUND 00Z. IMPROVING CONDITIONS
EXPECTED AFTER MIDNIGHT /07Z/.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
HIGH PRESSURE WILL BUILD ACROSS SOUTHERN CA...PRODUCING A DRY WEST
TO NORTHWESTERLY FLOW ACROSS THE FORECAST AREA. MOISTURE WILL BE
SCOURED OUT WEDNESDAY...BUT MAY STILL BE SUFFICIENT FOR ISOLATED
SHOWERS AND THUNDERSTORMS MAINLY ACROSS THE HIGHER ELEVATIONS. BUT
BY THURSDAY...PRECIP CHANCES WILL BE NEGLIGIBLE. A WARMING TREND IS
ALSO EXPECTED...WITH BELOW NORMAL TEMPERATURES APPROACHING NORMAL
VALUES BY THE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...HIRSCH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
355 AM MST MON SEP 10 2012
.SYNOPSIS...
A WEAK UPPER LOW WILL INTERACT WITH A MOIST AIRMASS OVER ARIZONA AND
SOUTHEAST CALIFORNIA...LEADING TO ABOVE AVERAGE STORM CHANCES
THROUGH TUESDAY. THERE WILL BE LARGE VARIATIONS IN STORM COVERAGE
AND INTENSITY FROM DAY TO DAY...WITH STORMS LIKELY TODAY AND
TUESDAY OVER SOUTH-CENTRAL ARIZONA. HIGH TEMPERATURES WILL BE BELOW
NORMAL THROUGH THURSDAY. DRY AIR MOVES IN DURING THE LATTER HALF OF
THE WEEK WITH STORM CHANCES ENDING OVER SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA WEDNESDAY...AND OVER SOUTH-CENTRAL ARIZONA BY
FRIDAY. A GRADUAL WARMING TREND WILL ACCOMPANY THE DRIER AIR.
&&
.DISCUSSION...
TODAY THROUGH WEDNESDAY...A BATCH OF SHOWERS AND THUNDERSTORMS
DEVELOPED OVER SANTA CRUZ COUNTY BEFORE MIDNIGHT AND HAS WORKED ITS
WAY INTO NORTHWEST PINAL AND EASTERN MARICOPA COUNTIES...BUT IN A
WEAKENED STATE. THE SHOWERS APPEAR TO BE BE ASSOCIATED WITH A
CIRCULATION EVIDENT IN THE WATER VAPOR IMAGERY CENTERED
SOUTH-SOUTHWEST OF NOGALES. THE RUC PICKED UP ON THIS VORT MAX BUT
DID NOT PLACE THE PRECIP CORRECTLY. THE 00Z NAM AND GFS DIDNT PICK
UP ON IT THOUGH THE 06Z VERSIONS NOW HINT AT SOMETHING.
MEANWHILE...THE UPPER LOW IS CENTERED OVER FAR NORTHERN BAJA. THE
LATEST OPERATIONAL MODELS DEPICT THE MAIN AREAS OF VORTICITY CLOSER
TO THE LOW CENTER AS WOULD BE EXPECTED. THE OMEGA AND UPPER LEVEL
DIVERGENCE FIELDS DIFFER CONSIDERABLY THOUGH WITH THE GFS PRODUCING
ITS TYPICAL SPORADIC BULLSEYES AND ASSOCIATED QPF MAXIMA. AS
USUAL...THERE ARE TREMENDOUS DIFFERENCES IN THE MODEL QPF WITH THE
NAM CHARACTERISTICALLY ON THE LOW SIDE...THOUGH NOT AS LOW AS THE
NMM6KM. THE NAM/GFS/SREF BASED POPS ALL CONTINUE TO DEPICT WELL
ABOVE NORMAL PRECIP CHANCES ACROSS THE FORECAST AREA TODAY AND
TUESDAY AS THE LOW FINALLY TRACKS NORTHEASTWARD. JUST WHERE THE MORE
INTENSE SHOWER/STORM ACTIVITY WILL BE FOR OUR FORECAST AREA IS VERY
DIFFICULT TO FIGURE OUT. THE AREA WHERE STORMS WERE MOST ACTIVE
SUNDAY SHOULD HAVE SOME STABILIZATION OF THE BOUNDARY LAYER TO
OVERCOME...YET BOTH THE NAM AND GFS DEPICT PRECIP FOR THAT AREA
AGAIN TODAY. SOUTH-CENTRAL ARIZONA SHOULD BE LESS STABILIZED FROM
LAST NIGHT BUT THIS MORNINGS SHOWERS MIGHT LEAD TO INHIBITED
DEVELOPMENT LATER ON. THE 00Z LOCAL WRF HAS NOT BEEN RELIABLE OF
LATE AS IT HAS FAILED TO EVEN INITIALIZE SIGNIFICANT CONVECTION. A
MIX OF LOCALLY HEAVY RAIN AND STRONG WINDS WILL BE POSSIBLE ANYWHERE
IN THE FORECAST AREA TODAY...LESS SO OVER PORTIONS OF SOUTHEAST
CALIFORNIA TUESDAY. ON WEDNESDAY...THE LOW WILL BE EAST OF ARIZONA
AND BARELY BE A SHORT WAVE BUT AN UPSTREAM KICKER SHORT WAVE MAY
STILL BE OVER EASTERN PORTIONS OF THE FORECAST AREA. HOWEVER...THERE
WILL BE SIGNIFICANTLY LESS MOISTURE TO WORK WITH AND THUS PRECIP
CHANCES DROP DRAMATICALLY. HIGH TEMPERATURES WILL BE WELL BELOW
NORMAL THROUGH TUESDAY AT MOST LOCATIONS. OVERALL FORECASTS REFLECT
A MULTIMODEL BLEND.
THURSDAY THROUGH SUNDAY...
THE GFS AND ECMWF DIFFER ON WHERE HIGH PRESSURE WILL BE CENTERED
DURING THE LATTER HALF OF THE WEEK. THE GFS HAS IT OVER ARIZONA
WHEREAS THE ECMWF IS FURTHER WEST AND HAS WEAK LINGERING TROUGHING
OVER NEW MEXICO. THE ECMWF IS ALSO SLOWER TO DRY THINGS OUT BUT WITH
A NORTHERLY COMPONENT TO THE FLOW...IT WILL BE DIFFICULT TO HOLD ON
TO ANY MEANINGFUL MOISTURE. EXCEPT FOR A SLIGHT CHANCE OVER FAR
EASTERN PORTIONS OF THE FORECAST AREA THURSDAY...EXPECT DRY
CONDITIONS THROUGH SUNDAY. MEANWHILE...TEMPS WILL SLOWLY WARM UP BUT
IT DOES NOT APPEAR THAT THEY WILL GET MUCH ABOVE NORMAL.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...MOSTLY
CLOUDY SKIES AND LIGHT AND VARIABLE WINDS ARE EXPECTED THROUGH
MONDAY MORNING. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE FOCUSED
MORE OVER EAST-CENTRAL ARIZONA ON MONDAY AFTERNOON AND EVENING.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...THERE IS A
CHANCE OF ISOLATED SHOWERS AND THUNDERSTORMS...MAINLY IN SOUTHEAST
CALIFORNIA THROUGH MONDAY MORNING. WINDS WILL GENERALLY BE
LIGHT...BUT COULD BECOME GUSTY IF STORMS DEVELOP IN THE AREA.
OTHERWISE...SKIES WILL REMAIN CLOUDY...WITH CLOUD BASES AOA 10 KFT.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
HIGH PRESSURE WILL BUILD ACROSS SOUTHERN CA...PRODUCING A DRY WEST
TO NORTHWESTERLY FLOW ACROSS THE FORECAST AREA. MOISTURE WILL BE
SCOURED OUT WEDNESDAY...BUT MAY STILL BE SUFFICIENT FOR ISOLATED
SHOWERS AND THUNDERSTORMS MAINLY ACROSS THE HIGHER ELEVATIONS. BUT
BY THURSDAY...PRECIP CHANCES WILL BE NEGLIGIBLE. A WARMING TREND IS
ALSO EXPECTED...WITH BELOW NORMAL TEMPERATURES APPROACHING NORMAL
VALUES BY THE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
AVIATION...MCLANE
FIRE WEATHER...HIRSCH
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
729 PM EDT TUE SEP 11 2012
.SYNOPSIS...
HIGH PRESSURE WILL RIDGE INTO THE FORECAST AREA FROM THE NORTH
THROUGH THURSDAY. DRY WEATHER ALONG WITH SLIGHTLY COOLER THAN NORMAL
TEMPERATURES WILL CONTINUE.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE FORECAST AREA FROM
THE NORTH. MOISTURE TRAPPED UNDER THE STRONG INVERSION WILL
CONTINUE TO SUPPORT SOME CLOUDINESS. MODEL TIME-HEIGHT DISPLAYS
SUPPORT PARTLY CLOUDY OR MOSTLY CLEAR SKIES. A WEAK SHORT WAVE
OVER THE AREA THIS EVENING IS EXPECTED TO DISSIPATE AROUND 06Z.
SO WILL HAVE A FEW CLOUDS UNTIL THAT TIME...THEN MOSTLY CLEAR
FOR THE REST OF THE NIGHT. EXPECT LOWS SIMILAR TO LAST NIGHT
WITH READINGS IN THE MIDDLE 50S TO AROUND 60.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
THE NAM AND GFS SHOW THE RIDGE CONTINUING TO EXTEND INTO THE
FORECAST AREA FROM THE NORTHEAST. SUBSIDENCE ASSOCIATED WITH THE
UPPER-LEVEL RIDGE SHOULD HELP MAINTAIN THE STRONG INVERSION. MODEL
TIME-HEIGHT DISPLAYS SHOW MOISTURE WILL REMAIN TRAPPED BELOW THIS
INVERSION AND SUPPORT SOME CLOUDINESS...BUT GENERALLY EXPECT PARTLY
CLOUDY TO MOSTLY CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS CLOSE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
AS THE HIGH SHIFTS EASTWARD DURING THE WEEKEND...AN EASTERLY FLOW
WILL CIRCULATE INCREASING MOISTURE INTO THE FORECAST AREA AND
ISENTROPIC LIFT MAY LEAD TO SHOWERS. THE MODELS ALSO SHOW A DIFFUSE
FRONT AND ASSOCIATED MOISTURE MOVING INTO THE AREA. THE GFS ENSEMBLE
MEANS SUPPORT POPS OF 20 TO 30 PERCENT. THE GFS ENSEMBLE MEANS
SUPPORT TEMPERATURES A FEW DEGREES BELOW NORMAL.
&&
.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
VFR CONDITIONS EXPECTED AT MOST TERMINALS THROUGH MOST OF THE 24
HOUR TAF PERIOD.
MID LEVEL CLOUDINESS IS STARTING TO DIMINISH AS THE SUN IS
SETTING. THERE IS A WEAK SHORT WAVE BUT BOTH RUC AND NAM FURTHER
WEAKEN THIS FEATURE AROUND 06Z. SO WILL GO WITH SCATTERED CLOUDS
UNTIL THAT TIME...THEN CLEAR. LOW LEVELS REMAIN FAIRLY DRY. LIGHT
WINDS EXPECTED OVERNIGHT. QUESTION REGARDS EXTENT OF CLOUD COVER
LATE TONIGHT. DECIDED TO GO MOSTLY CLEAR AFTER MIDNIGHT. MODELS
SHOW SOME MID LEVEL WEAKNESS IN THE RIDGE AFTER 12Z WEDNESDAY.
SO DECIDED TO GO SCATTERED CLOUDS 6-8 KFT. AIRMASS REMAINS DRY
BUT AGS WENT TO 3 MILES THIS MORNING FOR ONE HOUR. DECIDED TO KEEP
A TEMPO GROUP FOR AGS 10Z-12Z IN THE MORNING FOR VBSYS AS LOW AS
4 MILES IN GROUND FOG. OTHERWISE...NO MORE VSBYS ISSUES EXPECTED
AS CONDITIONS SHOULD BE VFR FOR MOST OF PERIOD.
EXTENDED AVIATION OUTLOOK...NO IMPACTS TO AVIATION EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS GOODLAND KS
840 PM MDT TUE SEP 11 2012
.UPDATE...
ISSUED AT 837 PM MDT TUE SEP 11 2012
00Z NAM/RUC AND 23Z HRRR SUPPORT PREVIOUS THINKING THAT WINDS
INITIALLY BEHIND THE COLD FRONT WILL GUST IN THE 30 TO 40 MPH
RANGE WITH SOME GUSTS TO 45 MPH POSSIBLE IN FAR EASTERN COLORADO
FOR A FEW HOURS. HAVE ALSO PULLED POPS FOR MOST OF THE NIGHT WITH
JUST A SMALL CHANCE ACROSS THE NORTHWEST CORNER OF THE AREA BY
12Z.
WILL CONTINUE TO MONITOR TRENDS AND ADJUST GRIDS AS NECESSARY.
UPDATE ISSUED AT 533 PM MDT TUE SEP 11 2012
WILL AWAIT 00Z DATA BEFORE MAKING AN UPDATE THIS EVENING. PRIMARY
CONCERN TONIGHT IS TIMING OF THE COLD FRONT AND POST FRONTAL WINDS
BEHIND IT.
AT PRESENT TIME 18Z/21Z DATA SUGGESTING WIND GUSTS OF 35 TO 45 MPH
WILL BE COMMON GENERALLY ALONG AND WEST OF THE CO/KS BORDER AFTER
03Z WHERE 3 HOUR PRESSURE RISES OF 5-7 MB EXPECTED. NOT SURE WE
WILL REACH 3 HOUR REQUIREMENT OF WIND GUSTS OF 45 MPH OR GREATER
FOR A WIND ADVISORY SO NO HIGHLITES EXPECTED PRESENTLY.
OTHER CONCERN IS THAT SLIGHT CHANCE/LOW CHANCE POPS THROUGH
MIDNIGHT MAY BE A BIT OVERDONE GIVEN THE BETTER MOISTURE AND JET
ENERGY REMAINS TO OUR WEST. FROM 06Z-12Z MAY NEED TO BUMP UP POPS
ACROSS THE FAR WEST/NORTHWEST WHERE THE MOISTURE AND JET ENERGY
FINALLY ARRIVES WHILE FURTHER EAST MAY NEED TO BRING POPS DOWN
GIVEN A DECREASING AVAILABILITY OF MOISTURE AND LIFT.
WILL FINE TUNE THE FORECAST ONCE THE 00Z DATA STARTS TO ARRIVE.
&&
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 136 PM MDT TUE SEP 11 2012
A TROUGH CAN BE SEEN ON WATER VAPOR OVER SOUTHERN NEVADA. THE LATEST
VISIBLE SATELLITE SHOWING A MOSTLY CLEAR SKY EAST OF THE ROCKIES.
THE 18Z SURFACE CHART SHOWS A TROUGH EXTENDING FROM EASTERN NEW
MEXICO ACROSS EASTERN COLORADO TO EASTERN SOUTH DAKOTA.
THE TROUGH OVER THE GREAT BASIN WILL MOVE EAST INTO THE ROCKIES
TONIGHT AND WEDNESDAY. THE SURFACE TROUGH WILL SHIFT SOUTHEAST
TONIGHT AND WEDNESDAY. A COLD FRONT WILL MOVE INTO THE PLAINS BEHIND
THE TROUGH LATE TONIGHT AND WEDNESDAY. POPS WILL INCREASE FROM
SLIGHT CHANCE FOR THUNDERSTORMS THIS EVENING NEAR THE TROUGH IN
EASTERN COLORADO TO CHANCES FOR SHOWERS AS INSTABILITY DECREASES
BEHIND THE FRONT OVERNIGHT. CHANCE POPS WILL BE ACROSS THE ENTIRE FA
WEDNESDAY AS BETTER RH AND DYNAMICS MOVE THROUGH. THE NORTHWEST FA
WILL HAVE LIKELY POPS WHERE MOISTURE IS MOST FAVORABLE. ONCE AGAIN
INSTABILITY IS LACKING SO WILL LIMIT THUNDER TO ISOLATED.
MIN TEMPERATURES WILL COOL DOWN TO THE MID 50S WEST TO THE LOWER 60S
EAST. MAX TEMPERATURES WEDNESDAY WILL RANGE FROM THE MID TO UPPER
60S BEHIND THE FRONT AND LOWER TO MID 70S NEAR THE FRONT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 210 PM MDT TUE SEP 11 2012
MAIN TROUGH AXIS IS STILL EXPECTED TO PASS OVER OUR CWA WED
NIGHT...WITH THE BEST LARGE SCALE ASCENT AND MOISTURE IN PLACE
ACROSS THE CWA WED EVENING. SHOWERS AND ISOLATED THUNDERSTORMS WILL
INCREASE IN COVERAGE OVER THE AREA THROUGH THE EVENING...AND THEN
MOVE EAST/SOUTHEAST WITH TROUGH. COVERAGE SHOULD THEN DECREASE
THROUGH THURSDAY MORNING...THOUGH A FEW LINGERING SHOWERS COULDNT BE
RULED OUT IN THE SOUTH THURSDAY AFTERNOON. WITH ALL AVAILABLE
GUIDANCE NOW IN GENERAL AGREEMENT ON TIMING/POSITION OF PRECIP I
FELT COMFORTABLE INCREASING POPS TO CATEGORICAL CATEGORY WED
EVENING ACROSS THE AREA. THERE IS STILL SOME SPREAD REGARDING
RAINFALL AMOUNTS...HOWEVER MUCH OF THE AREA SHOULD GET AT LEAST A
FEW TENTHS OF AN INCH OF RAIN...MORE DEPENDING ON WHERE THE
MODERATE BANDS OF PRECIP SET UP. TEMPERATURE OF THURSDAY SHOULD BE
IN THE 60S ACROSS MUCH OF THE AREA...WITH LOW 70S IN THE NORTH
WHERE CLEARING IS EXPECTED EARLIEST.
WITH A DRY/STABLE/COOL AIRMASS IN PLACE THU NIGHT WE COULD SEE ONE
OF THE COOLER NIGHTS SINCE LAST SPRING. CURRENT FORECAST HIGHS IN
THE UPPER 30S/LOW 40S ACROSS THE AREA IS IN LINE WITH WHAT OCCUR ED
LAST SAT NIGHT...HOWEVER WITH TD VALUES ADVERTISED TO DROP INTO THE
LOW 30S BY SOME GUIDANCE...COLDER TEMPERATURES ARE CERTAINLY
POSSIBLE.
DRY CONDITIONS AND MODERATING TEMPERATURES ARE EXPECTED FRIDAY INTO
NEXT WEEKEND AS A SHORTWAVE RIDGE BUILDS BACK OVER THE AREA.
TEMPERATURES WILL REMAIN BELOW NORMAL IN THE 70S FRIDAY AND NEAR
NORMAL IN THE LOW 80S SATURDAY. HIGHS ON SUNDAY MAY REACH THE UPPER
80S AT A FEW LOCATIONS WITH GOOD WAA AHEAD OF NEXT APPROACHING
SYSTEM. THE GOOD NEWS IS THAT THIS WOULD BE THE WARMEST DAY OF THE
ENTIRE FORECAST PERIOD...SO NO 100 DEGREE DAYS ON THIS FORECAST
CYCLE. ANOTHER UPPER LEVEL TROUGH IS EXPECTED TO MOVE ACROSS THE
NORTHERN PLAINS EARLY NEXT WEEK...BRINGING ANOTHER SHOT OF
PRECIPITATION AND COOLER TEMPERATURES BACK TO THE REGION. THERE IS
STILL A LOT OF UNCERTAINTY IN REGARDS TO THE TIMING/TRACK OF THIS
SYSTEM...HOWEVER IT DOES APPEAR TO SHOW A LOT OF SIMILARITIES TO THE
SYSTEM WE ARE EXPECTING THIS WEEK. I KEPT SLIGHT CHANCE/CHANCE POPS
IN PLACE MON AND MONDAY NIGHT WHERE CURRENT GUIDANCE IS TIMING
PRECIP WITH THIS SYSTEM.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 521 PM MDT TUE SEP 11 2012
VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT BOTH GLD AND
MCK. A COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS EVENING
BRINGING STRONG WINDS BEHIND IT. THE FRONTAL PASSAGE IS EXPECTED
AROUND 06Z...WITH SCATTERED MID LAYER CLOUDS AND NORTH-NORTHEAST
WINDS OF 20KTS AND GUSTS UP TO 32KTS EXPECTED AFTER THE FRONT
PASSES. THE WINDS WILL CONTINUE TO BE STRONG THROUGH THE TAF
PERIOD...AND CLOUD BASES WILL LOWER THROUGHOUT THE AFTERNOON
TOMORROW. A FEW SHOWERS ARE POSSIBLE AT BOTH SITES AS THE LOWER
ATMOSPHERE BECOMES SATURATED DURING THE DAY...WITH THE BEST CHANCE
FOR PRECIPITATION OUTSIDE THE RANGE OF THIS TAF PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...99
SHORT TERM...FS
LONG TERM...DR
AVIATION...99/JJM
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
630 PM CDT TUE SEP 11 2012
...UPDATED AVIATION SECTION...
.SYNOPSIS...
ISSUED AT 104 PM CDT TUE SEP 11 2012
AN IMPRESSIVE CYCLONE WAS MATURING ALONG THE MANITOBA-SASKATCHEWAN
BORDER TODAY. RAP ANALYSIS SUGGESTED A COMPACT 110KT JET STREAK ON
THE IMMEDIATE SOUTHEAST SIDE OF THE CYCLONE OVER CENTRAL MANITOBA.
THE SURFACE WAS RESPONDING NICELY TO THIS WITH A 985MB SURFACE LOW
ANALYZED THROUGH SURFACE OBSERVATIONS. CLOSER TO HOME...A VERY
WEAK...SUBTLE MID LEVEL DISTURBANCE WAS MOVING ACROSS WESTERN KANSAS
INTO SOUTHERN NEBRASKA...WHICH WAS PRODUCING NOTHING MORE THAN A FEW
MID AND HIGH LEVEL CLOUDS ACROSS THE REGION. AT THE SURFACE...THE
COLD FRONT TIED TO THE CANADA STORM EXTENDED FROM NORTHEASTERN SOUTH
DAKOTA TO WESTERN NEBRASKA LATE THIS AFTERNOON. A FAIRLY TIGHT
PRESSURE GRADIENT AHEAD OF THIS FRONT (AND A LEE TROUGH ACROSS
EASTERN COLORADO AND FAR WESTERN KANSAS) RESULTED IN STRONG WINDS OF
20 TO 25 KNOTS ACROSS MUCH OF KANSAS...NEBRASKA...AND OKLAHOMA. A
VERY DRY ATMOSPHERE WAS PRESENT IN THE WARM (AND WINDY) SECTOR WITH
DEWPOINTS MAINLY IN THE UPPER 30S TO LOWER 40S ACROSS WESTERN KANSAS
AND NEBRASKA AND THE TEXAS PANHANDLE. AS SURFACE TEMPERATURES
CONTINUED TO RISE THROUGH THE LOWER 90S...RELATIVE HUMIDITY WAS
FALLING TO 15 TO 20 PERCENT...RESULTING IN WIDESPREAD NEAR CRITICAL
TO CRITICAL FIRE WEATHER CONDITIONS.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 313 PM CDT TUE SEP 11 2012
A COLLECTION OF SUBTROPICAL SHORTWAVE PERTURBATIONS OVER THE DESERT
SOUTHWEST WILL CONTINUE ITS MOVEMENT NORTHEAST THROUGH THE EVENING
AND TONIGHT...APPROACHING SOUTHWEST COLORADO AND NORTHEAST NEW
MEXICO BY DAYBREAK WEDNESDAY. MEANWHILE...THE SURFACE COLD FRONT
TIED TO THE CANADA STORM WILL REACH ROUGHLY A LAMAR CO-HILL CITY
KS-LINCOLN NE LINE BY DAYBREAK. THROUGH THE NIGHT...LOW LEVEL
PRESSURE GRADIENT WILL KEEP WINDS UP IN THE 15 TO 20 KNOT RANGE
THROUGH THE NIGHT...AND AS A RESULT TEMPERATURES WILL ONLY FALL INTO
THE MID TO UPPER 60S FOR LOWS FOR MOST AREAS OF SOUTHWEST AND WEST
CENTRAL KANSAS. SOME AREAS OF CENTRAL AND SOUTH CENTRAL KANSAS WILL
SEE TEMPERATURES BOTTOMING OUT ONLY IN THE 68 TO 70 DEGREE RANGE.
THERE IS A SUBSTANTIAL HIGH TEMPERATURE FORECAST CHALLENGE
WEDNESDAY...ESPECIALLY ACROSS WEST CENTRAL KANSAS (NORTHWEST OF A
GARDEN CITY TO LACROSSE LINE)...AS THE FRONT WILL INITIATE COLD AIR
ADVECTION FROM THE NORTH IN THESE AREAS BY MIDDAY. THE QUESTION IS
HOW MUCH DIRECT INSOLATION WILL OFFSET THE INITIAL COLD
ADVECTION...AS OVERALL CLOUD COVER SHOULD STILL BE CONFINED TO AREAS
FARTHER NORTH DURING THE DIURNAL MAXIMUM OF THE AFTERNOON. AM
LEANING MORE TOWARD A COMPROMISE OF THE NAM12 AND ECMWF FOR 18Z AND
00Z COLD FRONT TIMING AND ASSOCIATED SURFACE TEMPERATURES. A LOW
LEVEL THERMAL RIDGE WILL EXTEND NORTHEASTWARD AHEAD OF THE
FRONT...WHICH BY EARLY TO MID AFTERNOON SHOULD EXTEND FROM ROUGHLY
MEADE TO BUCKLIN TO PRATT. ALONG AND SOUTHEAST OF THIS
LINE...AFTERNOON TEMPERATURES SHOULD REACH THE LOWER TO MID 90S.
CONVERGENCE ALONG THE FRONT AND SURFACE LOW...ESPECIALLY SOUTH OF
DODGE CITY TO THE OKLAHOMA BORDER...WILL LIKELY BE ENOUGH TO
INITIATE ONE OR TWO THUNDERSTORMS IN ENVIRONMENT OF ABOUT 600 TO 900
J/KG OF SURFACE BASED CAPE IN THE HOT AIRMASS WITH LIMITED SURFACE
MOISTURE. WILL CARRY 20 POPS IN THIS AREA (SOUTHEAST OF ROUGHLY
MEADE TO BUCKLIN TO PRATT). THE MAIN PRECIPITATION EVENT TIED TO
THE 800-700MB FRONT WILL BE AFTER THE WEDNESDAY (DAY) PERIOD.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 241 PM CDT TUE SEP 11 2012
MEDIUM RANGE MODELS INDICATE AN UPPER LEVEL TROUGH OF LOW PRESSURE
MOVING EAST OUT OF THE COLORADO ROCKIES INTO THE WESTERN HIGH PLAINS
WEDNESDAY NIGHT AND THURSDAY BRINGING A REASONABLE CHANCE FOR PRECIP
TO PORTIONS OF WESTERN AND CENTRAL KANSAS EARLY IN THE PERIOD. A
COLD FRONT ATTENDANT TO A LARGER SCALE UPPER LEVEL TROUGH
TRANSITIONING EAST OUT OF THE NORTHERN PLAINS INTO THE GREAT LAKES
REGION, WILL PUSH SOUTHEAST INTO WESTERN KANSAS WEDNESDAY NIGHT
AHEAD OF THE UPPER LEVEL SHORTWAVE. AMPLE LOW LEVEL MOISTURE IS
EXPECTED TO POOL AHEAD OF THE APPROACHING FRONT WITH H85 DEWPOINTS
UP AROUND 10C IN CENTRAL AND WESTERN KANSAS AS INDICATED BY THE GEM,
GFS, AND ECMWF. HOWEVER, MODEL SOUNDINGS SHOW A FAIRLY WEAK FLOW
ALOFT ACROSS WESTERN KANSAS INITIALLY, BUT GRADUALLY INCREASING AS
AN UPPER LEVEL JET AXIS BEGINS TO FINALLY EDGE SOUTHEASTWARD ACROSS
NEBRASKA WITH A RIGHT ENTRANCE REGION JUST NOSING INTO KANSAS BY
EARLY THURSDAY MORNING. ADDITIONALLY, THE SOUNDINGS SHOW A LACK OF
STRONG INSTABILITY (CAPE) LATE WEDNESDAY NIGHT INTO EARLY THURSDAY
WITH NEAR SATURATED PROFILES. IN FACT, ALL MODELS INDICATE THE BEST
CHANCE FOR PRECIP IN ASSOCIATION WITH POST-FRONTAL H7 FRONTOGENESIS
BANDING LATE WEDNESDAY NIGHT INTO EARLY THURSDAY ACROSS MUCH OF
CENTRAL AND SOUTHWEST KANSAS. WILL KEEP 60 TO 70 POPS IN ACROSS
MUCH OF THE FORECAST AREA LATE WEDNESDAY NIGHT INTO EARLY THURSDAY.
TEMPERATURES WILL BE BELOW NORMAL THURSDAY IN WAKE OF THE COLD
FRONTAL PASSAGE EXPECTED LATE WEDNESDAY. ADDITIONALLY, INCREASED
LOW/MID LEVEL CLOUDS AND EXPECTED WIDESPREAD PRECIP EARLY TO MID DAY
THURSDAY WILL LIMIT CLIMBING TEMPERATURES. THE GEM, GFS, AND ECMWF
SHOW COOLER AIR FILTERING SOUTH INTO WESTERN KANSAS WITH H85
TEMPERATURES DROPPING DOWN TO AROUND 10C TO 12C ACROSS CENTRAL AND
SOUTHWEST KANSAS. AGAIN, WITH INCREASED CLOUDS AND LINGERING PRECIP
HIGHS COULD STRUGGLE TO REACH UP INTO THE 60S(F). THE BETTER CHANCE
FOR WARMER TEMPERATURES MAY COME ACROSS WEST CENTRAL AND EXTREME
SOUTHWEST KANSAS WHERE CLOUDS MAY POTENTIALLY SCATTER THURSDAY
AFTERNOON AS THE UPPER LEVEL SYSTEM PUSHES EAST. A GRADUAL WARMING
TREND IS THEN LIKELY THROUGH THE WEEKEND AS WEAK UPPER LEVEL RIDGING
BRIEFLY DEVELOPS ACROSS THE INTERMOUNTAIN WEST BEFORE BREAKING DOWN
SATURDAY AND SUNDAY. NEAR THE SURFACE, A GENERAL SOUTHEASTERLY FLOW
WILL DEVELOP FRIDAY AS SURFACE HIGH PRESSURE MIGRATES EAST INTO THE
OHIO RIVER VALLEY. MEANWHILE, MORE OF A SOUTHERLY COMPONENT WILL
TAKE OVER SATURDAY INTO SUNDAY AS A LEE SIDE TROUGH OF LOW PRESSURE
DEVELOPS IN EASTERN COLORADO HELPING TO ADVECT SLIGHTLY WARMER AIR
INTO THE REGION SUPPORTING THE WARMING TREND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 630 PM CDT TUE SEP 11 2012
A STRONG COLD FRONT IS PROGGED TO MOVE SOUTH ACROSS SOUTHERN
NEBRASKA AND NORTHERN KANSAS TONIGHT BEFORE MOVING THROUGH
SOUTHWEST KANSAS LATE IN THE MORNING INTO THE AFTERNOON TOMORROW.
BEFORE FROPA WINDS ARE FORECATED TO BE FROM THE SOUTH AT 10 TO 20
KNOTS GUSTING TO OVER 20 KNOTS AT TIMES. WS IS STILL POSSIBLE
ACROSS THE DDC AND HYS TERMINALS OVERNIGHT WITH WINDS INCREASING
TO AROUND 55 KNOTS AT 2000 FEET. WINDS BEHIND THE FRONT ARE
FORECASTED TO SHIFT TO THE NORTH AT 10 TO 15 KNOTS GUSTING TO
AROUND 20 KNOTS AT TIMES. VFR CONDITIONS ARE ANTICIPATED OVERNIGHT
WITH JUST A FEW HIGH CLOUDS POSSIBLE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 67 92 55 65 / 10 20 80 80
GCK 64 86 52 67 / 10 20 80 60
EHA 65 84 52 66 / 10 20 80 70
LBL 66 90 53 66 / 10 20 70 70
HYS 67 87 53 67 / 10 10 70 50
P28 70 97 63 65 / 10 20 70 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR KSZ030-031-
043>046-063>066-075>081-085>090.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...JJOHNSON
AVIATION...HOVORKA_42
AREA FORECAST DISCUSSION
NWS BILLINGS MT
334 AM MDT MON SEP 10 2012
.SHORT TERM...VALID FOR TDY AND TUE...
CRITICAL FIRE WEATHER CONDITIONS WILL BE THE MAIN MESSAGE FOR THIS
AFTERNOON THROUGH TONIGHT WHILE A 500-HPA SHORT WAVE TROUGH SHIFTS
EAST AND DEEPENS OVER CENTRAL CANADA. WE HAVE HIGH CONFIDENCE THAT
RED FLAG CRITERIA WILL BE MET THIS AFTERNOON INTO TONIGHT. THAT IS
NOT TRUE FOR TUE...WHEN CONFIDENCE IN RED FLAG CONDITIONS ACROSS A
WIDESPREAD AREA IS ACTUALLY DECREASING SUBSTANTIALLY WITH TIME.
EARLY THIS MORNING...A LEAD AND RELATIVELY WEAK 500-HPA SHORT WAVE
IS CROSSING THE AREA...AND GENERATING A BIT OF CONVECTION IN SOUTH
CENTRAL MT AROUND LIVINGSTON. THE 06 UTC NAM AND 05 UTC HRRR WOULD
SUGGEST THIS ACTIVITY WILL WANE BY ABOUT 12 UTC...BUT THE SCENARIO
DOES WARRANT SOME LOW POPS FOR A FEW PLACES IN SOUTH CENTRAL MT IN
THE 12 TO 15 UTC TIME FRAME BASED ON RECENT RADAR TRENDS.
TODAY...PRE-FRONTAL MIXING WILL EXTEND TO AROUND 600 HPA OVER MUCH
OF SOUTH CENTRAL MT BASED ON A CONSENSUS OF FORECAST SOUNDINGS. IT
LOOKS LIKE GUSTS OF 30 MPH WILL BE COMMON...WITH SOME 40 MPH GUSTS
VERY PLAUSIBLE FOR PLACES LIKE LIVINGSTON SINCE BUFKIT-BASED TOOLS
REVEAL SUBSIDENCE THROUGH THE DEPTH OF THE MIXED LAYER...WITH SOME
35 KT WINDS AT ITS TOP. ONE EXCEPTION TO ALL OF THIS COULD BE OVER
SOUTHEASTERN MT...WHERE WINDS ALOFT DO NOT INCREASE UNTIL CLOSE TO
00 UTC. THE EXPECTED MIXING SUPPORTS HIGHS NEAR 90 F IN MANY SPOTS
TODAY...THOUGH BASED ON A BIT OF COOLING ALOFT EARLY TODAY...HIGHS
WERE ACTUALLY LOWERED A BIT OVER PREVIOUS FORECASTS FOR AREAS LIKE
LIVINGSTON AND HARLOWTON. THAT IS IN LINE WITH THE SET OF MOS FROM
THE 00 UTC GUIDANCE. FINALLY...WE HAVE SOME LOW POPS IN PLACE THIS
AFTERNOON FROM THE BIG HORN MOUNTAINS NORTHEAST INTO FAR SOUTHEAST
MT BASED ON THE FACT THAT THE LAST SEVERAL MODEL CYCLES HAVE SHOWN
HIGH-BASED CONVECTION IN THOSE AREAS. CALIBRATED PROBABILITIES FOR
DRY THUNDERSTORMS FROM THE 21 UTC SREF ARE EVEN NEAR 10 PERCENT IN
THAT REGION...SO WE WILL INCLUDE A MENTION OF THE POTENTIAL WITHIN
OUR RED FLAG WARNING.
TONIGHT...THE SURFACE COLD FRONTAL PASSAGE IS EXPECTED TO OCCUR IN
THE 00 TO 06 UTC TIME FRAME. SURFACE PRESSURE RISES WILL BE IN THE
5 HPA/3 HOUR RANGE BASED ON THE 00 UTC NAM AND GFS...AND 500 M AGL
WINDS WILL CLOSE IN ON 30 KT. THUS...WE STILL EXPECT A PERIOD WITH
WIND GUSTS OF 35 MPH...THOUGH WE HAVE TO ADMIT THAT SOUNDINGS FROM
THE 00 UTC GUIDANCE LEAVE A BIT TO BE DESIRED SINCE THEY ALLOW FOR
THE BOUNDARY LAYER TO STABILIZE ENOUGH TO REDUCE MOMENTUM TRANSFER
BEHIND THE FRONT. THUS...THERE IS A BIT OF UNCERTAINTY WITH REGARD
TO HOW LONG WINDS WILL STAY UP BEHIND THE FRONT.
TUE...FORECAST SOUNDINGS SUGGEST THAT BOUNDARY LAYER MIXING SHOULD
ONLY EXTEND TO ABOUT 750 HPA...AND IT IS ONLY ABOVE THAT LEVEL THE
MID-LEVEL WINDS WILL BE SIGNIFICANT. THIS BRINGS INTO QUESTION THE
POTENTIAL FOR GUSTY SURFACE WINDS OUTSIDE OF SOUTHEASTERN MT...AND
ADDING TO THAT UNCERTAINTY ARE THE SURFACE PRESSURE FALLS SHOWN IN
SOUTH CENTRAL MT BY AFTERNOON. SOMETIMES TURBULENT MIXING BEHIND A
COLD FRONT AND SHORT WAVE IS MORE ROBUST THAN MODELS SUGGEST...AND
SO WE MADE FEW CHANGES TO THE CURRENT FORECAST. HOWEVER...THERE IS
A CHANCE THAT THE BAKER AND MILES CITY AREAS WILL BE THE ONLY ONES
WITH GUSTY WINDS REQUIRING A RED FLAG ON TUE SINCE THOSE SPOTS ARE
IN CLOSER PROXIMITY TO STRONGER FLOW BELOW 750 HPA. SCHULTZ
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
MODEL AGREEMENT IS NOT AS GOOD TONIGHT AS DURING PREVIOUS RUNS.
BROAD UPPER LEVEL TROUGH CONTINUES ACROSS THE REGION
WED...WITH REINFORCING FRONT ON WED AFTN/EVE. ECMWF BRINGS THE
SHORTWAVE SUPPORT FOR THE REINFORCING FRONT THROUGH IN THE FORM OF
TWO SEPARATE WAVES...WHILE THE GFS BRINGS IT THROUGH AS ONE
STRONG...COHERENT SHORTWAVE. A BLEND OF LONG RANGE MODELS SEEMS TO
BE THE BEST SOLUTION FOR WED...AND FOR MUCH OF THE EXTENDED AT
THIS POINT. SO...DID NOT REALLY CHANGE MUCH WED-THURS. UPPER
TROUGH IS SLOW TO MOVE THROUGH...KEEPING COOL DRY AIR ADVECTION
IN PLACE THROUGH THURS. AN UPPER RIDGE BUILDS INTO THE REGION
LATE THURS AND WILL DOMINATE THE PATTERN FOR FRI...IN RESPONSE TO
TROUGHING BUILDING UPSTREAM. TEMPS SHOULD RETURN TO ABOVE NORMAL
LEVELS ON FRI AND SAT. MODELS HANDLE THE REMAINDER OF THE PERIOD
QUITE DIFFERENTLY. AT SOME POINT LATE IN THE WEEKEND OR EARLY NEXT
WEEK IT LOOKS LIKE ANOTHER COOLDOWN WILL BEGIN...BUT CANNOT REALLY
DETERMINE EXACTLY WHEN THIS WILL BE AS MODEL CONSISTENCY IS POOR
DURING THIS TIMEFRAME. PREVIOUS MODEL RUNS HAD THIS COOLDOWN
BEGINNING SAT/SAT NIGHT...SO IT APPEARS MODELS ARE HAVING A VERY
HARD TIME FORECASTING THE TIMING OF THIS FEATURE. INTRODUCED
SLIGHT CHANCE POPS OVER THE MOUNTAINS SUNDAY AS THE ECMWF HAS GONE
TO A SOLUTION THAT SLIDES AN UPPER LEVEL LOW SOUTHWARD THROUGH
WESTERN MT/IDAHO. STILL...NOT REALLY BUYING THAT AS IT REPRESENTS
A TREMENDOUS DEPARTURE FROM MODELS RUNS OVER THE LAST COUPLE OF
DAYS. BOTTOM LINE IS...COOL WEATHER WED INTO THURS...A WARMUP FRI
INTO SAT...THEN ANOTHER COOLDOWN PROBABLY BEGINNING SUN....WITH NO
PRECIP EXPECTED THROUGH AT LEAST SAT NIGHT. STC
&&
.AVIATION...
MAINLY VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH
TONIGHT. A WEAK DISTURBANCE WILL GENERATE ISOLATED SHOWERS AND
THUNDERSTORMS ACROSS WESTERN AND CENTRAL ROUTES OVER THE NEXT FEW
HOURS...BUT NOT EXPECTING ANY MVFR OR IFR WITH THE STORMS. THE
MAIN AVIATION HAZARD THROUGH THE PERIOD WILL BE WIND. WESTERLY
WINDS WILL BECOME GUSTIER ACROSS THE REGION BY EARLY THIS
AFTERNOON AHEAD OF A COLD FRONT. THE COLD FRONT WILL RACE THROUGH
THE REGION FROM MID AFTERNOON THROUGH THIS EVENING...SWITCHING
WINDS TO A NW DIRECTION WITH GUSTS OVER 30 KTS POSSIBLE. A FEW
SHOWERS AND THUNDERSTORMS ARE ALSO POSSIBLE ACROSS EASTERN ROUTES
DURING THE LATE AFTERNOON AND EVENING HOURS...JUST AHEAD OF THE
COLD FRONT. STC
&&
.PRELIMINARY POINT TEMP/POPS...
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 090 051/071 042/067 039/069 044/082 052/079 051/073
2/T 10/U 00/U 00/U 00/U 11/U 11/U
LVM 085 040/071 033/066 031/069 037/079 043/077 040/071
2/T 10/U 01/U 10/U 00/U 10/U 01/U
HDN 093 051/073 042/070 040/071 042/083 050/082 050/075
1/N 20/U 00/U 00/U 00/U 11/U 11/U
MLS 090 052/072 041/069 038/069 043/080 050/080 053/072
1/U 20/N 00/U 00/U 00/U 00/U 01/B
4BQ 093 053/072 042/070 040/069 044/081 049/082 051/075
2/T 20/N 00/U 00/U 00/U 00/U 01/U
BHK 089 052/071 041/068 038/066 043/078 048/079 049/071
1/U 20/N 00/U 10/U 00/U 00/U 01/U
SHR 091 048/072 039/066 038/067 041/079 046/079 048/072
2/T 20/U 00/U 00/U 00/U 01/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING IN EFFECT UNTIL MIDNIGHT MDT TONIGHT FOR
ZONE 117.
RED FLAG WARNING IN EFFECT UNTIL MIDNIGHT MDT TUESDAY NIGHT
FOR ZONES 123>128-133.
RED FLAG WARNING IN EFFECT FROM NOON TODAY TO MIDNIGHT MDT
TUESDAY NIGHT FOR ZONES 129>132.
WY...RED FLAG WARNING IN EFFECT FROM NOON TODAY TO MIDNIGHT MDT
TUESDAY NIGHT FOR ZONES 274-284.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1105 PM EDT TUE SEP 11 2012
.SYNOPSIS...
FAIR WEATHER WILL PREVAIL THIS WEEK AS CANADIAN HIGH PRESSURE
SETTLES INTO THE REGION AS IT SHIFTS SLOWLY EAST. AN APPROACHING
COLD FRONT MAY BRING A FEW SHOWERS OVER THE WEEKEND AND INTO EARLY
NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 11:00 PM TUESDAY...RIDGING SFC AND ALOFT TO DOMINATE THE ILM
CWA OVERNIGHT. SUBSIDENCE IN THE MID-LAYERS TO PREVENT ANY VERTICAL
DEVELOPMENT WITH THE CU/SC THAT DEVELOPS OVER THE ADJACENT ATLANTIC
WATERS AND SPORADICALLY MOVES ONSHORE DURING THIS PERIOD. THE NE-E
FLOW IN THE LOWER LEVELS WILL FORCE/LIFT WHAT MOISTURE THAT IS
AVAILABLE UPWARDS...WITH OROGRAPHIC LIFT AIDING ANY CU/SC
DEVELOPMENT WELL INLAND WITHIN THE ILM CWA. WILL GO WITH MOSTLY
CLEAR TO PTLY CLOUDY FOR SKY CONDITIONS TONIGHT. HRRR INDICATES
SPOTTY PCPN OR ISOLATED SHRA TO DEVELOP OVER THE ADJACENT
WATERS...AND PUSH ONSHORE BEFORE DISSIPATING ALTOGETHER. FOG
ALGORITHM PORTRAITS PATCHY TO AREAS OF FOG DEVELOPMENT FOR A SHORT
4-6 HR WINDOW ENDING/DISSIPATING BY 8-9 AM WEDNESDAY.
DRY AND RELATIVELY COOL WEATHER TO CONTINUE THROUGHOUT THE NEAR TERM
AS CANADIAN HIGH PRESSURE CENTERED ACROSS THE MID-ATLANTIC STATES TO
MARTHAS VINEYARD WHICH EVIDENTLY MAINTAINS A STEADY BUT LIGHT NE-E
FLOW ESPECIALLY FELT ACROSS THE COASTAL CAROLINAS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 300 PM TUESDAY...FALL LIKE WEATHER WILL CONTINUE THROUGH MID
WEEK AS CANADIAN HIGH PRESSURE SETTLES DOWN OVER THE SOUTHEAST
WHILE SHIFTING SLOWLY EAST. AS THE CENTER SLIPS OFF THE NEW
ENGLAND COAST...IT WILL CONTINUE TO RIDGE DOWN INTO THE CAROLINAS.
THIS WILL HELP VEER WINDS AROUND THROUGH THE PERIOD TO THE
NORTHEAST WED INTO THURS AND EAST BY END OF THE PERIOD WHICH WILL
PRODUCE A SLIGHT INCREASE IN MOISTURE COMING FROM THE ATLANTIC
WATERS. AN OVERALL RISE IN MOISTURE WILL BRING PCP WATER VALUES
FROM CLOSE TO A HALF INCH WED TO OVER AN INCH BY LATE THURS IN
MOISTURE COMING IN FROM THE E-NE. THEREFORE EXPECT SUNNY WEATHER
ON WED BUT SHOULD SEE MORE IN THE WAY OF CU DEVELOPMENT THURS
AFTERNOON ESPECIALLY ALONG SEA BREEZE BOUNDARY AND MAINLY OVER
NORTH CAROLINA ZONES. MOISTURE PROFILES AND SOUNDING DATA SHOW
MOISTURE LOCKED IN BELOW INVERSION REACHING UP TO 90% IN THE 2-4K
FT LEVEL ON THURS. EASTERLY FETCH OF MOISTURE MAY HELP TO PRODUCE
SOME FOG OR LOW STRATUS ON FRI IN THE EARLY MORNING CLOSER TO THE
COAST.
IN THE MID TO UPPER LEVELS THE RIDGE BECOMES MORE PRONOUNCED OVER
THE EAST COAST...BUT GETS SQUEEZED OUT BY END OF PERIOD BY BACK
BUILDING TROUGH OVER THE ATLANTIC AND TROUGH DIGGING DOWN FROM THE
UPPER GREAT LAKES. OVERALL EXPECT PLENTY OF DRY AIR AND SUBSIDENCE
THROUGHOUT THE MID LEVELS THROUGHOUT MOST OF WED AND INTO THURS.
AS FOR TEMPS...HEIGHTS WILL BE RISING THROUGH MID WEEK WITH A RISE
IN 850 TEMPS FROM 12C ON WED UP CLOSE TO 15C BY THURS. THE VERY DRY
AIR INITIALLY WILL CONTINUE TO PRODUCE LARGE DIURNAL SWINGS BUT THE
INCREASED MOISTURE IN THE LOW LEVELS BY THURS WILL BRING DEWPOINT
TEMPS UP ABOUT 10 DEGREES TO NEAR 65 CLOSER TO THE
COAST...ESPECIALLY NC COAST. THEREFORE EXPECT DAY TIME HIGHS
RISING A COUPLE OF DEGREES BETWEEN WED AND THURS...BETWEEN 80 AND
85 MOST PLACES. OVERNIGHT LOWS WILL INCREASE ALSO FROM CLOSER TO
60 WED IN MORE IDEAL RADIATIONAL COOLING CONDITIONS TO CLOSER TO
65 BY FRI MORNING.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...LARGE 5H RIDGE ACROSS THE EAST TRANSITIONS TO
MID-LEVEL SPLIT FLOW AS A NORTHERN STREAM LOW DRAGS A COLD FRONT
TOWARDS THE CAROLINAS ON SATURDAY. THIS FRONT TRIES TO PUNCH INTO A
VERY DRY AIR MASS...AND IS ACCOMPANIED ONLY BY WEAK (AND WEAKENING)
MID-LEVEL FORCING. WITH PWATS STILL ONLY AROUND ONE-INCH...AND MEX
P24 VALUES STILL WELL BELOW CLIMO...EXPECT THE WKND TO BE MOSTLY
DRY. HOWEVER...CANNOT RULE OUT SOME ISOLATED SHOWERS EITHER SAT OR
SUN AND THUS WILL KEEP INHERITED SCHC POP.
A MORE ROBUST MID-LEVEL SYSTEM ROTATES NORTHEAST FROM THE GULF COAST
REGION FOR THE BEGINNING OF THE WEEK...AND IS ACCOMPANIED BY AN
INCREASING SURFACE REFLECTION AND WARM FRONT. ALTHOUGH IT APPEARS
BEST FORCING REMAINS WEST OF THE IMMEDIATE CWA...LIFT ALONG THE WARM
FRONT IN A MOISTENING AIR MASS WILL PROVIDE INCREASING SHOWER
POTENTIAL MONDAY INTO TUESDAY AND WILL CARRY LOW-CHC FOR NOW...BUT
THIS WILL BE THE BEST CHANCE FOR RAIN THROUGH THE EXTENDED.
MAX TEMPS WILL BE SLIGHTLY ABOVE CLIMO FRI/SAT BEFORE FALLING BACK
TO NEAR SEASONABLE LEVELS FOR THE BEGINNING OF THE WEEK. MINS EACH
NIGHT WILL BE AROUND TO JUST ABOVE CLIMATOLOGICAL NORMS.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 00Z...EXPECT VFR TO PREVAIL THROUGH THE PERIOD...WITH
EXCEPTION OF POSSIBLE BRIEF MVFR AT KLBT BEFORE DAYBREAK DUE TO
FOG. OVERNIGHT...GENERALLY LIGHT NORTHEAST WINDS WILL CONTINUE.
MAY SEE A FEW LINGERING MID-LEVEL CLOUDS...BUT OVERALL EXPECT
NEARLY CLEAR SKIES. GIVEN IDEAL RADIATIONAL COOLING
OVERNIGHT...MAY SEE MVFR FOG AT KLBT JUST BEFORE DAYBREAK. THOUGH
CONFIDENCE IS A BIT LOWERED...HAVE OPTED TO INTRODUCE TEMPO GROUP.
AFTER DAYBREAK...VFR WILL PREVAIL WITH NORTHEAST WINDS GRADUALLY
INCREASING TO AOB 10 KTS. GIVEN FCST SOUNDINGS AND
GUIDANCE...CONTINUE TO ANTICIPATE FEW/SCT DIURNAL CU TO DEVELOP
ACROSS THE AREA IN THE AFTERNOON...AROUND 5-6KFT.
THE EXTENDED OUTLOOK THROUGH SUNDAY...POTENTIAL FOR BRIEF REDUCED
VSBYS AT FOG PRONE TERMINALS KCRE/KLBT IN THE PRE-DAWN HOURS
THURSDAY THROUGH SUNDAY. OTHERWISE EXPECT VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 11:05 PM TUESDAY...ELONGATED CENTER OF HIGH PRESSURE EXTENDED
FROM THE MID-ATLANTIC STATES NE TO MARTHAS VINEYARD. THIS PRESSURE
PATTERN WILL YIELD A NE-E WIND DIRECTION. A SLIGHTLY PINNED SFC PG
ACROSS THE EASTERN CAROLINAS WILL PRODUCE 10-15 KT WIND SPEEDS.
DECAYING TROPICAL SWELL AND WIND DRIVEN WAVES TO COMBINE TO PRODUCE
2 TO 4 FT OVERALL SEAS.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
CANADIAN HIGH PRESSURE WILL SETTLE DOWN OVER THE SOUTHEAST WHILE
SHIFTING SLOWLY EAST. AS THE CENTER SLIPS OFF THE NEW ENGLAND
COAST...IT WILL CONTINUE TO RIDGE DOWN INTO THE CAROLINAS. THIS WILL
HELP VEER WINDS AROUND THROUGH THE PERIOD FROM N-NE EARLY WED TO NE
TO E BY THURS NIGHT. GRADIENT FLOW WILL WEAKEN WITH WINDS NE
AROUND 15 KTS AND UP TO 20 IN OUTER WATERS ON WED. BY LATE THURS
WINDS WILL BE DOWN TO 10 TO 15 KTS.
OVERALL SEAS WILL DIMINISH A BIT BUT THE ONSHORE PUSH WILL KEEP
SEAS IN THE 2 TO 4 FT RANGE. LONGER PERIOD SWELL WILL DROP OFF BY
WED EVENING.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...HIGH PRESSURE RIDGING DOWN THE COAST
THROUGH THE PERIOD CREATES PREDOMINANTLY E/NE WINDS ACROSS THE
WATERS. THE PRESSURE GRADIENT WILL EASE THROUGH THE WKND...SO THE
STRONGEST WINDS...10-15 KTS...WILL OCCUR EARLY FRIDAY...BEFORE
FALLING TO LESS THAN 10 KTS THROUGH THE REST OF THE PERIOD. BY
LATE SUNDAY...RETURN FLOW WILL ONCE AGAIN DEVELOP...TURNING WINDS
TO THE SW BUT REMAINING LESS THAN 10 KTS. SEAS WILL BE PRIMARILY
2-4 FT THANKS TO A NE WIND WAVE..BUT MAY BUILD SUNDAY AS SOME
INCREASING LONG PERIOD SWELL FROM A TROPICAL DISTURBANCE WORKS
INTO THE LOCAL WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...SGL
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 GREEN BAY WI
1044 PM CDT TUE SEP 11 2012
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW PRESSURE
MOVING NORTHEAST ALONG THE NORTH DAKOTA-MINNESOTA BORDER WHILE HIGH
PRESSURE IS SITUATED OVER THE APPALACHIANS. AHEAD OF THE FRONT...A
FEW SPOTTY SHOWERS ARE PRESENT OVER CENTRAL MINNESOTA AND MID AND
HIGH CLOUDS ARE ADVANCING INTO NORTHWEST WISCONSIN. 12Z SOUNDINGS
INDICATE A VERY DRY AIRMASS AHEAD OF THE FRONT IN THE LOW LEVELS
WHERE DEWPOINT DEPRESSIONS ARE IN THE UPPER TEENS TO LOWER 20S AT
850MB. AS THE FRONT MOVES ACROSS THE REGION LATE TONIGHT INTO
WEDNESDAY...LIGHT SHOWER POTENTIAL IS THE MAIN FORECAST CONCERN.
TONIGHT...THE COLD FRONT OVER THE NORTHERN MISSISSIPPI VALLEY WILL
MOVE INTO NORTH-CENTRAL WISCONSIN LATE TONIGHT. STILL NO MOISTURE
AHEAD OF THE FRONT AS DEWPOINTS ARE ONLY IN THE 40S TO LOW 50S OVER
THE PLAINS. INSTEAD WILL SEE SCT TO BKN MID AND HIGH CLOUDS
ASSOCIATED WITH THE FRONTAL ZONE PUSH ACROSS NORTHWEST INTO CENTRAL
WISCONSIN AFTER MIDNIGHT. ELSEWHERE...WILL SEE MOSTLY CLEAR
CONDITIONS WITH A WARM SOUTHWEST WIND. LOWS RANGING FROM THE UPPER
50S NORTH TO THE MIDDLE 60S NEAR LAKE MICHIGAN.
WEDNESDAY...THE FRONT WILL CONTINUE TO SLOWLY MOVE TO THE SOUTHEAST
ACROSS NORTHEAST WISCONSIN DURING THE MORNING AND EAST-CENTRAL
WISCONSIN DURING THE AFTERNOON. AS MID-LEVEL HEIGHT FALLS OCCUR...
A BKN MID-LEVEL CLOUD DECK WILL BE IN PLACE ACROSS THE NORTHWEST
HALF OF THE FORECAST AREA FOR MUCH OF THE DAY. MID-LEVEL FGEN WILL
WORK ITS WAY SOUTHEAST ACROSS NORTHEAST AND CENTRAL WISCONSIN...BUT
CLOUD BASES WILL BE NEAR OR ABOVE 10 KFT ACCORDING TO PROGGED
SOUNDINGS. LOW LEVELS WILL REMAIN DRY...SO THINK IT WILL BE TOUGH
FOR ANY LIGHT SHOWERS TO MEASURE AT THE SURFACE. BUT MODELS ARE
INSISTENT ON SPITTING OUT LIGHT QPF AND INHERITED FORECAST CALLS FOR
A LOW CHANCE OF SHOWERS. SO WILL KEEP A MENTION OF SLIGHT CHANCE OF
SHOWERS IN THE FORECAST. HIGHS WILL BE COOLER OVER CENTRAL AND
NORTH-CENTRAL WISCONSIN BEHIND THE FRONT AND BENEATH CLOUD COVER.
WILL GO WITH TEMPS RANGING FROM NEAR 70 NORTHWEST TO THE LOWER 80S
SOUTHEAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH NEXT TUESDAY...PCPN TRENDS FOR
THE END OF THE WORK WEEK/BEGINNING OF THE WEEKEND...AND TEMPS...
ARE THE MAIN FCST CONCERNS.
MODELS STILL TRYING TO SETTLE ON A SOLUTION FOR THE END OF THE
WEEK...BUT THE GENERAL TREND HAS BEEN TO SPEED UP THE PASSAGE OF
THE POST-FRONTAL PCPN BAND DURING THE WEDS NGT-THU NGT PERIOD.
EVEN THE DEEP AND POSSIBLY CLOSED-OFF UPPER SYSTEM IS EXPECTED TO
SWING THROUGH FAIRLY QUICKLY ON FRIDAY. HAVE ADJUSTED POPS
ACCORDINGLY...BUT DID BLEND A BIT WITH THE SLIGHTLY SLOWER 00Z
ECMWF RUN FOR BETTER CONSISTENCY AND THE POSSIBILITY THAT THE
NEW RUNS ARE TOO FAST. HIGHEST POPS OCCUR WEDS NGT/THU...AND
LINGER IN OUR SE COUNTIES INTO THU NGT. CHC POPS ARE STILL
WARRANTED FOR EASTERN WI FRI INTO FRI NGT...UNTIL THE UPPER
LOW SHIFTS EAST. COOLER MAX TEMPS IN THE 60S ARE EXPECTED ON
THU/FRI.
THE WEEKEND IS LOOKING NICE...WITH WEAK HIGH PRESSURE OVER THE
REGION. HIGH TEMPS SHOULD WARM BACK TO ABOVE NORMAL BY SUNDAY.
THE NEXT FRONTAL SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA
SOMETIME DURING THE MON-TUES TIME FRAME. THE TIMING OF THE
FRONT IS IN QUESTION...SO ONLY SLGT CHC/CHC POPS WILL BE
INCLUDED DURING THE PERIOD FOR NOW.
&&
.AVIATION...OVERALL SURFACE WINDS HAVE DIMINISHED TO 15 KNOTS OR
LESS. HOWEVER LOW LEVEL WIND SHEAR CONDITIONS WILL LINGER
OVERNIGHT. VFR CONDITIONS WILL CONTINUE TONIGHT INTO WEDNESDAY.
VFR CIGS WILL BE LOWERING TUESDAY AFTERNOON OVER NORTHWEST
WISCONSIN AS A COLD FRONT DROPS INTO THE STATE.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
619 PM CDT TUE SEP 11 2012
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW PRESSURE
MOVING NORTHEAST ALONG THE NORTH DAKOTA-MINNESOTA BORDER WHILE HIGH
PRESSURE IS SITUATED OVER THE APPALACHIANS. AHEAD OF THE FRONT...A
FEW SPOTTY SHOWERS ARE PRESENT OVER CENTRAL MINNESOTA AND MID AND
HIGH CLOUDS ARE ADVANCING INTO NORTHWEST WISCONSIN. 12Z SOUNDINGS
INDICATE A VERY DRY AIRMASS AHEAD OF THE FRONT IN THE LOW LEVELS
WHERE DEWPOINT DEPRESSIONS ARE IN THE UPPER TEENS TO LOWER 20S AT
850MB. AS THE FRONT MOVES ACROSS THE REGION LATE TONIGHT INTO
WEDNESDAY...LIGHT SHOWER POTENTIAL IS THE MAIN FORECAST CONCERN.
TONIGHT...THE COLD FRONT OVER THE NORTHERN MISSISSIPPI VALLEY WILL
MOVE INTO NORTH-CENTRAL WISCONSIN LATE TONIGHT. STILL NO MOISTURE
AHEAD OF THE FRONT AS DEWPOINTS ARE ONLY IN THE 40S TO LOW 50S OVER
THE PLAINS. INSTEAD WILL SEE SCT TO BKN MID AND HIGH CLOUDS
ASSOCIATED WITH THE FRONTAL ZONE PUSH ACROSS NORTHWEST INTO CENTRAL
WISCONSIN AFTER MIDNIGHT. ELSEWHERE...WILL SEE MOSTLY CLEAR
CONDITIONS WITH A WARM SOUTHWEST WIND. LOWS RANGING FROM THE UPPER
50S NORTH TO THE MIDDLE 60S NEAR LAKE MICHIGAN.
WEDNESDAY...THE FRONT WILL CONTINUE TO SLOWLY MOVE TO THE SOUTHEAST
ACROSS NORTHEAST WISCONSIN DURING THE MORNING AND EAST-CENTRAL
WISCONSIN DURING THE AFTERNOON. AS MID-LEVEL HEIGHT FALLS OCCUR...
A BKN MID-LEVEL CLOUD DECK WILL BE IN PLACE ACROSS THE NORTHWEST
HALF OF THE FORECAST AREA FOR MUCH OF THE DAY. MID-LEVEL FGEN WILL
WORK ITS WAY SOUTHEAST ACROSS NORTHEAST AND CENTRAL WISCONSIN...BUT
CLOUD BASES WILL BE NEAR OR ABOVE 10 KFT ACCORDING TO PROGGED
SOUNDINGS. LOW LEVELS WILL REMAIN DRY...SO THINK IT WILL BE TOUGH
FOR ANY LIGHT SHOWERS TO MEASURE AT THE SURFACE. BUT MODELS ARE
INSISTENT ON SPITTING OUT LIGHT QPF AND INHERITED FORECAST CALLS FOR
A LOW CHANCE OF SHOWERS. SO WILL KEEP A MENTION OF SLIGHT CHANCE OF
SHOWERS IN THE FORECAST. HIGHS WILL BE COOLER OVER CENTRAL AND
NORTH-CENTRAL WISCONSIN BEHIND THE FRONT AND BENEATH CLOUD COVER.
WILL GO WITH TEMPS RANGING FROM NEAR 70 NORTHWEST TO THE LOWER 80S
SOUTHEAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH NEXT TUESDAY...PCPN TRENDS FOR
THE END OF THE WORK WEEK/BEGINNING OF THE WEEKEND...AND TEMPS...
ARE THE MAIN FCST CONCERNS.
MODELS STILL TRYING TO SETTLE ON A SOLUTION FOR THE END OF THE
WEEK...BUT THE GENERAL TREND HAS BEEN TO SPEED UP THE PASSAGE OF
THE POST-FRONTAL PCPN BAND DURING THE WEDS NGT-THU NGT PERIOD.
EVEN THE DEEP AND POSSIBLY CLOSED-OFF UPPER SYSTEM IS EXPECTED TO
SWING THROUGH FAIRLY QUICKLY ON FRIDAY. HAVE ADJUSTED POPS
ACCORDINGLY...BUT DID BLEND A BIT WITH THE SLIGHTLY SLOWER 00Z
ECMWF RUN FOR BETTER CONSISTENCY AND THE POSSIBILITY THAT THE
NEW RUNS ARE TOO FAST. HIGHEST POPS OCCUR WEDS NGT/THU...AND
LINGER IN OUR SE COUNTIES INTO THU NGT. CHC POPS ARE STILL
WARRANTED FOR EASTERN WI FRI INTO FRI NGT...UNTIL THE UPPER
LOW SHIFTS EAST. COOLER MAX TEMPS IN THE 60S ARE EXPECTED ON
THU/FRI.
THE WEEKEND IS LOOKING NICE...WITH WEAK HIGH PRESSURE OVER THE
REGION. HIGH TEMPS SHOULD WARM BACK TO ABOVE NORMAL BY SUNDAY.
THE NEXT FRONTAL SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA
SOMETIME DURING THE MON-TUES TIME FRAME. THE TIMING OF THE
FRONT IS IN QUESTION...SO ONLY SLGT CHC/CHC POPS WILL BE
INCLUDED DURING THE PERIOD FOR NOW.
&&
.AVIATION...GUSTY SURFACE WINDS WILL LET UP EARLY THIS
EVENING...BUT AS THE SURFACE WINDS DIMINISH THE LOW WIND SHEAR
WILL INCREASE FOR TONIGHT. OTHERWISE VFR CONDITIONS TO PREVAIL
TONIGHT INTO WEDNESDAY. A COLD FRONT DROPPING INTO THE STATE ON
WEDNESDAY WILL LESSON THE PRESSURE GRADIENT FOR DIMINISHED SURFACE
WINDS. ENOUGH MOISTURE MAY WORK INTO AT LEAST THE NORTHWEST HALF
OF THE STATE TO PRODUCE A FEW LIGHT SHOWERS.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
242 PM CDT MON SEP 10 2012
.SHORT TERM...TONIGHT AND TUESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
SHIFTING EAST OVER THE CENTRAL GREAT LAKES WHILE LOW PRESSURE IS
LOCATED OVER THE NORTHERN GREAT PLAINS. EXCEPT FOR CIRRUS FLOATING
OVER NORTH DAKOTA AND NORTHERN MINNESOTA...CLEAR SKIES EXIST ACROSS
MUCH OF THE MISSISSIPPI VALLEY AND THE GREAT PLAINS...OWING TO THE
VERY DRY AIRMASS AHEAD OF THE LOW PRESSURE. GUSTS AHEAD OF THE LOW
PRESSURE ARE ALSO REACHING INTO THE UPPER 20S TO LOWER 30S KTS WHICH
WILL BE SHIFTING INTO OUR AREA TOMORROW. WITH LITTLE THREAT OF
PRECIP...TEMPS AND WIND GUSTS ARE THE MAIN FORECASTS CONCERNS.
TONIGHT...HIGH PRESSURE WILL SHIFT TO THE APPALACHIANS WHILE LOW
PRESSURE MOVES ACROSS THE DAKOTAS. AHEAD OF THE LOW PRESSURE...THE
PRESSURE GRADIENT INCREASES SUBSTANTIALLY TONIGHT AND PRODUCES A LOW
LEVEL JET OF 40+ KNOTS ABOUT 1000 FT OFF THE SURFACE. THIS SHOULD
KEEP THE BOUNDARY LAYER CHURNED UP ESPECIALLY OVER HIGHER TERRAIN
AND PREVENT TEMPS FROM FALLING NEARLY AS COLD AS THE PAST COUPLE
NIGHTS. WILL GO WITH LOWS MAINLY IN THE 50S. OTHER THAN CIRRUS
DRIFTING OVERHEAD...SKIES WILL BE CLEAR.
TUESDAY...LOW PRESSURE WILL MOVE ACROSS MINNESOTA AND INTO FAR
NORTHWEST WISCONSIN BY 00Z WEDNESDAY. THE AIRMASS AHEAD OF THE
FRONT IS VERY DRY WITH DEWPOINTS IN THE 40S AND 50S...SO NO THREAT
OF ANY PRECIP AHEAD OF THE FRONT. THE TIGHT PRESSURE GRADIENT WILL
STILL BE THERE AND MIXING UP TO AROUND 900MB SHOULD BE ABLE TO
PRODUCE GUSTS 30 TO 35 MPH IN THE AFTERNOON. SW WINDS WILL CONTINUE
TO DRAW WARMER AIR INTO THE REGION FROM THE GREAT PLAINS AS 850MB
TEMPS INCREASE TO AROUND 20C. WILL NOT BE ABLE TO TAP INTO THIS AIR
THOUGH...SO THE SHALLOW MIXING WILL ONLY PLACE HIGHS INTO THE LOW TO
MID 80S.
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...MAIN FCST CONCERN
IS PCPN TRENDS THROUGH THE PERIOD...AND A BIG CHANGE IN TEMPERATURES
FROM WEDNESDAY INTO THURSDAY.
A COLD FRONT WILL ENTER NC WI ON TUESDAY NIGHT...BUT WITH AN INITIALLY
DRY AIR MASS AND UPPER FORCING LAGGING TO THE WEST OF THE FRONT...WILL
MAINTAIN THE DRY FCST. THE FRONT WILL SAG SE ACROSS THE FORECAST AREA
ON WEDS AND WEDS NGT...WITH POST-FRONTAL PCPN DEVELOPING DUE THE
INCOMING UPPER TROF...THE RRQ OF A STRG JET STREAK AND MID-LEVEL
FRONTOGENETIC FORCING. ECMWF/GFS/GEM/UKMET ALL SHOW SIMILAR TIMING...
WHICH WAS A BIT FASTER THAN OUR PREVIOUS FCST...AND PERHAPS 6 HOURS
FASTER THAN THE 12Z NAM. HOWEVER...GIVEN RECENT MODEL DIFFERENCES AND
A NEED TO MESH WITH FCSTS FROM SURROUNDING OFFICES...OPTED TO
CONTINUE WITH A BLENDED APPROACH FOR POPS. REGARDLESS...THE HIGHEST
POPS REMAIN CENTERED AROUND WEDS NGT AND THURSDAY. SUBSEQUENT FCSTS
MAY NEED TO BE A BIT MORE AGGRESSIVE ENDING THE PCPN OVER OUR NW
COUNTIES ON THU/THU NGT.
SECOND PROBLEM WITH POPS OCCURS FRIDAY INTO SATURDAY...AS THE GFS
SHIFTS THE UPPER TROF AND FRONT FAR ENOUGH EAST TO END THE PCPN OVER
WI...WHILE THE ECMWF CLOSES OFF A STG UPPER LOW OVER THE RGN...INDUCES
SFC CYCLOGENESIS...REGENERATES PCPN OVER MUCH OF WI...AND LINGERS
IT WELL INTO THE WEEKEND. THE ECMWF SEEMS OVERDONE COMPARED TO
THE ENSEMBLES...BUT IT SHOULD BE NOTED THAT IT HAS SHOWN AN UPPER
LOW IN THE WSTRN GREAT LKS/UPPER MIDWEST LATE IN THE WEEK FOR THE
PAST 5 MODEL RUNS. ONCE AGAIN...HAVE OPTED FOR THE PREFERRED MODEL
BLEND...BUT BIG CHANGES WILL BE NEEDED LATER IN THE WEEK IF THE
ECMWF SOLN LOOKS LIKE IT WILL VERIFY.
MUCH ABOVE NORMAL TEMPERATURES (LOW TO MID 80S) IN ADVANCE OF THE
FRONT WILL BE REPLACED BY SLIGHTLY COOLER THAN NORMAL 60S FOR THE
END OF THE WEEK. WEEKEND TEMPS ARE UP IN THE AIR DUE TO THE
PREVIOUSLY-MENTIONED MODEL DIFFERENCES.
&&
.AVIATION...VFR CONDITIONS THROUGH TOMORROW WITH LITTLE IN THE WAY
OF CLOUD COVER AND EXCELLENT VISIBILITY. LOW LEVEL WIND SHEAR WILL
BE THE ONLY CONCERN TONIGHT AS A LOW LEVEL JET INCREASES TO AROUND
40 KNOTS AT 800 FT AGL WITH SFC WINDS OF 5 TO 10 KTS. ONCE
TEMPERATURES WARM TUESDAY MORNING...WIND GUSTS OUT OF THE SOUTHWEST
WILL INCREASE GREATER THAN 20 KTS. SOME GUSTS UP TO 30 KTS WILL BE
POSSIBLE TUESDAY AFTERNOON.
MPC
&&
.MARINE...PERSISTENT AND STRENGTHENING SOUTH TO SOUTHWEST FLOW
WILL LEAD TO HAZARDOUS CONDITIONS FOR SMALL CRAFT TONIGHT THROUGH
WEDNESDAY. SMALL CRAFT ADVISORIES ARE ALREADY IN EFFECT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/KIECKBUSCH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1248 PM CDT MON SEP 10 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
311 AM CDT MON SEP 10 2012
MAIN FORECAST CONCERNS ARE ON THE WARMTH TODAY AND TUESDAY...THEN
WHEN PRECIPITATION ARRIVES FOR WEDNESDAY INTO WEDNESDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING COMING INTO BRITISH COLUMBIA AND THE PACIFIC
NORTHWEST...RIDGING ACROSS MUCH OF THE PLAINS INTO MANITOBA...AND
TROUGHING ALONG THE EAST COAST. SOME CIRRUS NOTED SPILLING OVER TOP
OF THE RIDGE INTO NORTHERN MINNESOTA. OTHERWISE...PLENTY OF
SUBSIDENCE UNDER THE UPPER RIDGE AS WELL AS DRY AIR RESULTING IN
CLEAR SKIES FROM THE CENTRAL PLAINS INTO THE FORECAST AREA.
REGARDING THE DRY AIR...GOES SOUNDER PRECIPITABLE WATER IMAGERY
SHOWED VALUES OF 0.3 TO 0.5 INCHES WHERE THE CLEAR SKIES ARE...OR
AROUND 50 PERCENT OF NORMAL. AT THE SURFACE...HIGH PRESSURE
STRETCHED FROM MISSOURI INTO LOWER MICHIGAN AND LEE TROUGHING WAS
PRESENT ALONG THE EAST SIDE OF THE ROCKIES. SOUTHERLY WINDS WERE
INCREASING OVER THE PLAINS INTO MINNESOTA...BOTH AT THE SURFACE AND
ALOFT. AT 850MB...PROFILER DATA SHOWED 40-50 KT SOUTHWEST WINDS
ACROSS THE DAKOTAS. THESE WINDS DOWNSLOPING OFF THE ROCKIES ARE
PRODUCING 22-27C 850MB TEMPS OVER THE DAKOTAS PER RAP ANALYSIS. OVER
THE FORECAST AREA...LIGHTER WINDS ASSOCIATED WITH THE SURFACE HIGH
ALLOWING THE TYPICAL COLD SPOTS TO DROP INTO THE UPPER 30S. ANY
VALLEY FOG THUS FAR HAS BEEN CONFINED TO THE WISCONSIN RIVER
VALLEY...AND EVEN THAT HAS NOT CONSISTENTLY STAYED IN PLACE.
TODAY THROUGH TUESDAY...MODELS ARE IN GOOD AGREEMENT SHOWING THE
UPPER TROUGHING COMING INTO BRITISH COLUMBIA DEEPENING AND SHIFTING
EAST TO SASKATCHEWAN BY 00Z WEDNESDAY. AS THIS OCCURS...THE UPPER
RIDGING OVER THE PLAINS GETS PUSHED EAST ACROSS THE FORECAST
AREA. IN ADDITION...THE LEE TROUGHING TURNS INTO A COLD FRONT AND
REACHES THE SIOUX FALLS AREA BY 00Z WEDNESDAY. THE HEAT BUILDING UP
ACROSS THE DAKOTAS AND THE STRENGTHENING WINDS WILL ACCOMPANY THE
EASTWARD PROGRESS OF THE UPPER RIDGE. 850MB TEMPS AT 12Z THIS
MORNING SHOULD RANGE FROM 9-12C EAST TO WEST. BY 00Z THIS
EVENING...THEY ARE PROGGED TO CLIMB TO AT LEAST 14-17C IF NOT A
LITTLE WARMER. WITH INCREASING SOUTHERLY WINDS...DRY AIR AND PLENTY
OF SUN OUTSIDE OF MAYBE SOME CIRRUS...WE SHOULD HAVE NO PROBLEM
MIXING TO 850MB. GOING HIGHS OF MIDDLE 70S TO LOWER 80S REFLECT THIS
WELL. A SOUTHERLY BREEZE WILL HELP TO KEEP LOW TEMPERATURES IN THE
50S TONIGHT. FURTHER WARMING CONTINUES INTO TUESDAY WITH 850MB TEMPS
REACHING 20-22C BY 18Z...OR 1.5-2 STANDARD DEVIATIONS ABOVE NORMAL.
THERE ARE INDICATIONS OF INCREASE CIRRUS DURING THE AFTERNOON...BUT
MOST OF THE DAY SHOULD SEE PLENTY OF SUN. WINDS WILL BE STRONGER...
WITH SOUTHWEST SPEEDS OF 25 KT AT 925MB AND 35KT AT 850MB. THE
COMBINATION OF THESE WINDS...STILL PLENTY OF DRY AIR AND THE SUN
SHOULD PROPEL TEMPERATURES UP INTO THE MIDDLE 80S TO AROUND 90. WITH
THE WARM...DRY AIR AND INCREASING WINDS...THERE ARE SOME FIRE
WEATHER CONCERNS WHICH ARE DISCUSSED IN THE FIRE WEATHER AFD
SECTION.
TUESDAY NIGHT AND WEDNESDAY...UPPER RIDGING IS PROGGED TO STRENGTHEN
ACROSS THE OHIO VALLEY INTO THE EASTERN GREAT LAKES REGION DURING
THIS TIME. THIS IN TURN HELPS TO HOLD THE FORECAST AREA UNDER
SOUTHWEST FLOW ALOFT. WITH THE COLD FRONT THAT REACHED SIOUX FALLS
AT 00Z WEDNESDAY HAVING A NEAR SOUTHWEST TO NORTHEAST ORIENTATION...
CLOSE TO PARALLELING THE UPPER FLOW...THE SLOW EASTWARD PROGRESS
MODELS HAVE TRENDED TO THE PAST FEW DAYS MAKES SENSE. LOOKS LIKE THE
COLD FRONT MAY REACH ROCHESTER AROUND 12Z WEDNESDAY...THEN SLOWLY
CROSS THE FORECAST AREA BY 00Z THURSDAY. NO CONCERN EXISTS ABOUT THE
FRONT INITIATING PRECIPITATION AHEAD OF IT...DUE TO A DRY CAPPED
AIRMASS IN PLACE. HOWEVER...BEHIND THE FRONT THINGS ARE MORE
INTERESTING. FIRST IN THE 500MB PATTERN...MODELS SHOW A POTENT
SHORTWAVE DROPPING DOWN THE BACK SIDE OF THE DEEP SOUTH CENTRAL
CANADA TROUGH...REACHING EASTERN MONTANA LATE WEDNESDAY. AN 80-120
KT JET AT THE TROPOPAUSE IS PROGGED TO DEVELOP AHEAD OF THIS POTENT
SHORTWAVE INTO NORTHERN MINNESOTA AND ONTARIO. THIS PLACES SOUTHERN
MINNESOTA INTO NORTHWEST WISCONSIN UNDER UPPER LEVEL DIVERGENCE.
ALSO IN THE 500MB PATTERN THERE IS AN UPPER LOW CURRENTLY NEAR BAJA
CALIFORNIA WHICH MODELS SHEAR APART AND LIFT INTO SOUTHERN MINNESOTA
BY 00Z THURSDAY. THIS FEATURE WILL HELP PRODUCE SOME DPVA. LASTLY...
ON THE BACK/NORTHWEST SIDE OF THE FRONT...LOW TO MID LEVEL
FRONTOGENESIS IS PROGGED TO INCREASE THROUGH THE DAY WEDNESDAY. SO
PLENTY OF FORCING EXISTS BEHIND THE FRONT TO PRODUCE PRECIPITATION.
THIS LEAVES MOISTURE THE ONLY ISSUE...WHICH DOES NOT LOOK TO BE A
PROBLEM AS PRECIPITABLE WATER VALUES CLIMB TO 1.5 INCHES BEHIND THE
FRONT. THEREFORE...PRECIPITATION DEVELOPMENT BEHIND THE FRONT WILL
OCCUR. THERE IS A SHOT SOME OF THIS COULD GET INTO NORTHWESTERN
PORTIONS OF THE FORECAST AREA PER THE 10.00Z GFS...BUT OVERALL MODEL
CONSENSUS KEEPS THE BULK OF IT NORTH AND WEST OF THE AREA ON
WEDNESDAY. REGARDING TEMPERATURES...WITH THE WARM AIRMASS IN PLACE
AND A SOUTHERLY BREEZE PERSISTING...TUESDAY NIGHT SHOULD SEE LOWS
FROM THE MIDDLE 50S TO MIDDLE 60S. 850MB TEMPS ARE A LITTLE COOLER
ON WEDNESDAY...14-18C...BUT SUN THROUGH CIRRUS ALONG/AHEAD OF THE
FRONT SHOULD BRING HIGHS UP INTO THE LOW TO MID 80S. BEHIND THE
FRONTAL PASSAGE...INCREASING MID/HIGH CLOUDS AND POSSIBLE
PRECIPITATION WILL RESULT IN SLIGHTLY COOLER CONDITIONS.
WEDNESDAY NIGHT...GOOD CONSENSUS EXISTS FOR THIS PERIOD TO BE WET...
ESPECIALLY FOR THE NORTHWEST HALF OF THE FORECAST AREA. UPPER LEVEL
DIVERGENCE WILL SHIFT OVER THE FORECAST AREA...ALONG WITH THE LOW TO
MID LEVEL FRONTOGENESIS. THIS IS ALL RELATED TO THE DEEP SOUTH
CENTRAL CANADA TROUGH LIFTING OUT TO THE NORTHEAST...AND THE POTENT
SHORTWAVE IN MONTANA SHIFTING INTO THE DAKOTAS AND CLOSING OFF INTO
AN UPPER LOW. AGAIN...PLENTY OF MOISTURE EXISTS WITH PRECIPITABLE
WATER VALUES UP AROUND 1.5 INCHES OR 160 PERCENT OF NORMAL. GIVEN
THE EXCELLENT CONTINUITY AND CONSENSUS FOR PRECIPITATION IN THE
NORTHWEST HALF OF THE FORECAST AREA...HAVE RAISED PRECIPITATION
CHANCES THERE TO 80 OR HIGHER. SOME NEGATIVE EPV NOTED IN CROSS
SECTIONS THAT GETS INGESTED INTO THE FRONTOGENESIS CIRCULATION.
THIS NEGATIVE EPV SHOULD PRODUCE CONVECTIVE BANDING AND SOME
ISOLATED THUNDERSTORMS...DESPITE THE LACK OF ANY CAPE. WITH THE
CONVECTIVE NATURE AND HIGH PRECIPITABLE WATER...THE QPF AMOUNTS IN
THE 10.00Z GFS/NAM OF UPWARDS OF 1 INCH IN 6 HOURS IS CERTAINLY
POSSIBLE. COMBINATION OF GRADUAL COLD ADVECTION BEHIND THE FRONT
ALONG WITH PRECIPITATION WILL RESULT IN COOLER TEMPERATURES COMPARED
TO TUESDAY NIGHT. FOLLOWED A BLEND OF GUIDANCE FOR LOWS.
.LONG TERM...THURSDAY THROUGH SUNDAY NIGHT
311 AM CDT MON SEP 10 2012
10.00Z ECMWF/GFS/GFS ENSEMBLES ARE IN GOOD AGREEMENT THROUGH ABOUT
FRIDAY...THEN DIFFERENCES BEGIN TO SHOW UP. THE 10.00Z CANADIAN IS
A FAST OUTLIER TO START OFF WITH AS IT DOES NOT HAVE THE POTENT
SHORTWAVE OVER THE WESTERN DAKOTAS AT 12Z THURSDAY LIKE OTHER
MODELS. AS SUCH...THIS MODEL WAS FOR THE MOST PART DISCOUNTED.
GENERAL THEME FROM THE ECMWF/GFS/GFS ENSEMBLES IS THAT THE POTENT
SHORTWAVE OVER THE WESTERN DAKOTAS WILL COME CLOSE TO OR ACROSS THE
FORECAST AREA ON FRIDAY AS A CLOSED OFF UPPER LOW. ALL FORCING FOR
PRECIPITATION LOOKS TO REMAIN TO THE EAST OF THE UPPER LOW...WHERE
THE FRONTOGENESIS IS OCCURRING. ON THURSDAY...HIGH CONFIDENCE EXISTS
THAT THE SOUTHEASTERN HALF OF THE FORECAST AREA WILL SEE RAIN...AS
THE FRONTOGENESIS FROM WEDNESDAY NIGHT PUSHES EAST. RAISED
PRECIPITATION CHANCES IN THIS AREA TO 70. PRECIPITATION CHANCES THEN
LOWER THROUGH FRIDAY...BUT DONT COMPLETELY GO AWAY DUE TO THE UPPER
LOW NEARBY. TEMPERATURES WILL DEFINITELY BE COOLER. HOW COOL DEPENDS
ON EXACTLY WHERE THE RAIN SETS UP. IT IS POSSIBLE THAT HIGHS ON
THURSDAY COULD GET STUCK IN THE 50S WHERE IT RAINS...VERSUS MID 60S
TO AROUND 70 WHERE IT DOESNT. COOL AIR ASSOCIATED WITH THE UPPER
LOW SHOULD HOLD HIGHS DOWN IN THE MID 60S FOR FRIDAY.
BEYOND FRIDAY...THE FORECAST PRETTY MUCH REVOLVES AROUND THE UPPER
LOW. OVER THE PAST 24 HOURS OR SO...HAVE SEEN VARIOUS GFS AND ECMWF
MODEL RUNS HANDLE THE UPPER LOW DIFFERENTLY. EVEN WITH THE 10.00Z
RUNS...THE ECMWF TAKES IT SLOWLY EAST ACROSS IOWA AND ILLINOIS FROM
FRIDAY INTO SATURDAY WHILE THE GFS HAS IT HEADING UP INTO EASTERN
ONTARIO. THE 09.06Z GFS RUN HAD THE UPPER LOW ON SATURDAY STILL OVER
THE FORECAST AREA. AS SUCH...FORECAST CONFIDENCE BEYOND FRIDAY IS
LOW. GENERAL THEME...THOUGH...IS ANY RAIN SHOULD FOR THE MOST PART
BE EAST OF THE FORECAST AREA...WHICH IS WHAT THE CONSENSUS APPROACH
GIVES. BY THE TIME WE APPROACH SUNDAY...THERE ARE INDICATIONS OF A
DEEPENING CENTRAL CANADA TROUGH INTO THE NORTHERN ROCKIES. IF THIS
DOES OCCUR AS FORECAST...WE SHOULD SEE A WARM UP AS SOUTHERLY FLOW
PICKS UP AHEAD OF THE TROUGHING. THE TEMPERATURE FORECAST PLAYS THIS
IDEA WITH HIGHS CLIMBING BACK INTO THE LOW TO MID 70S FOR SUNDAY.
&&
.AVIATION...THROUGH 18Z TUESDAY
1248 PM CDT MON SEP 10 2012
MAIN CONCERNS AT THE TAF SITES THROUGH THE PERIOD ARE BREEZY
SOUTH TO SOUTHWEST WINDS AND LOW LEVEL WIND SHEAR LATE TONIGHT
INTO EARLY TUESDAY MORNING. OTHERWISE PLAN ON VFR CONDITIONS. THE
AREA WILL BE IN A TIGHT PRESSURE GRADIENT WITH A SURFACE TROUGH
LOCATED ACROSS THE DAKOTAS AND HIGH PRESSURE CENTERED OVER THE
APPALACHIANS. PLAN ON SOUTH WINDS TODAY AT 15 TO 20 KTS WITH GUSTS
AROUND 29 KTS POSSIBLE...ESPECIALLY AT KRST. SURFACE WINDS WILL
SUBSIDE INTO THE 12 TO 14 KT RANGE THIS EVENING. A 45 TO 50 KT LOW
LEVEL JET IS EXPECTED TO DEVELOP AROUND 05Z AT THE TAF SITES. HAVE
INCLUDED WIND SHEAR IN THE TAF STARTING AT 1500 FT. THE LOW LEVEL
JET SHOULD DECREASE AROUND 13Z...BUT SURFACE WINDS ARE EXPECTED TO
RAPIDLY INCREASE AFTER SUNRISE. PLAN ON SOUTHWEST WINDS AT 15 TO
20 KTS WITH GUSTS AROUND 30 KTS BY LATE TOMORROW MORNING.
&&
.CLIMATE...TUESDAY
340 PM CDT SUN SEP 9 2012
HIGH TEMPERATURES WILL CLIMB TO AROUND 90 DEGREES MAINLY NORTHWEST
OF A CHARLES CITY IOWA TO BLACK RIVER FALLS LINE ON TUESDAY. THE
RECORD HIGHS FOR THIS DATE ARE...
LA CROSSE WI - 97 IN 1897
MEDFORD WI - 95 IN 1900
ROCHESTER MN - 94 IN 1931
AUSTIN MN - 92 IN 1948
CHARLES CITY IA - 96 IN 2000
DECORAH IA - 97 IN 1895
&&
.FIRE WEATHER...TODAY AND TUESDAY
311 AM CDT MON SEP 10 2012
INCREASING SOUTH TO SOUTHWEST WINDS TODAY AND TUESDAY WILL BRING
WARMER AIR INTO THE REGION. SPEEDS ON THESE WINDS LOOK TO RANGE FROM
15 TO 25 MPH WITH GUSTS UP TO 35 MPH. WITH PLENTY OF SUNSHINE...GOOD
MIXING WILL OCCUR...BRINGING TEMPERATURES UP TO 75 TO 80 TODAY AND
85 TO 90 ON TUESDAY. DEWPOINTS ARE A LITTLE TRICKY...SINCE THE WIND
DIRECTION FAVORS A RETURN FLOW OF MOISTURE. HOWEVER...THE GULF OF
MEXICO DOES NOT OPEN UP FOR THE RETURN OF MOISTURE UNTIL AT LEAST
LATE TUESDAY. THEREFORE...DEWPOINTS WILL TAKE THEIR TIME COMING
UP...BEING COUNTERED DURING THE AFTERNOONS DUE TO MIXING. CURRENT
THINKING IS THAT RELATIVE HUMIDITIES ARE GOING TO END UP IN THE 25
TO 35 PERCENT RANGE...LOWEST IN WESTERN PORTIONS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA.
WITH THE DRYING LANDSCAPE/MATURING VEGETATION AND THE ABOVE WEATHER
CONDITIONS...CONCERN IS THERE FOR SOME FIRES. HOWEVER...THE RELATIVE
HUMIDITIES ARE JUST ABOVE THE CRITICAL 25 PERCENT THRESHOLD NEEDED
FOR A FIRE WEATHER RELATED HAZARD. IN ADDITION...FIRE WEATHER USERS
AFFECTED IN OUR FORECAST AREA ARE ALRIGHT WITHOUT ANY FIRE WEATHER
RELATED HAZARD AT THIS TIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
311 AM CDT MON SEP 10 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
CLIMATE........BOYNE
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
610 AM CDT MON SEP 10 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
311 AM CDT MON SEP 10 2012
MAIN FORECAST CONCERNS ARE ON THE WARMTH TODAY AND TUESDAY...THEN
WHEN PRECIPITATION ARRIVES FOR WEDNESDAY INTO WEDNESDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING COMING INTO BRITISH COLUMBIA AND THE PACIFIC
NORTHWEST...RIDGING ACROSS MUCH OF THE PLAINS INTO MANITOBA...AND
TROUGHING ALONG THE EAST COAST. SOME CIRRUS NOTED SPILLING OVER TOP
OF THE RIDGE INTO NORTHERN MINNESOTA. OTHERWISE...PLENTY OF
SUBSIDENCE UNDER THE UPPER RIDGE AS WELL AS DRY AIR RESULTING IN
CLEAR SKIES FROM THE CENTRAL PLAINS INTO THE FORECAST AREA.
REGARDING THE DRY AIR...GOES SOUNDER PRECIPITABLE WATER IMAGERY
SHOWED VALUES OF 0.3 TO 0.5 INCHES WHERE THE CLEAR SKIES ARE...OR
AROUND 50 PERCENT OF NORMAL. AT THE SURFACE...HIGH PRESSURE
STRETCHED FROM MISSOURI INTO LOWER MICHIGAN AND LEE TROUGHING WAS
PRESENT ALONG THE EAST SIDE OF THE ROCKIES. SOUTHERLY WINDS WERE
INCREASING OVER THE PLAINS INTO MINNESOTA...BOTH AT THE SURFACE AND
ALOFT. AT 850MB...PROFILER DATA SHOWED 40-50 KT SOUTHWEST WINDS
ACROSS THE DAKOTAS. THESE WINDS DOWNSLOPING OFF THE ROCKIES ARE
PRODUCING 22-27C 850MB TEMPS OVER THE DAKOTAS PER RAP ANALYSIS. OVER
THE FORECAST AREA...LIGHTER WINDS ASSOCIATED WITH THE SURFACE HIGH
ALLOWING THE TYPICAL COLD SPOTS TO DROP INTO THE UPPER 30S. ANY
VALLEY FOG THUS FAR HAS BEEN CONFINED TO THE WISCONSIN RIVER
VALLEY...AND EVEN THAT HAS NOT CONSISTENTLY STAYED IN PLACE.
TODAY THROUGH TUESDAY...MODELS ARE IN GOOD AGREEMENT SHOWING THE
UPPER TROUGHING COMING INTO BRITISH COLUMBIA DEEPENING AND SHIFTING
EAST TO SASKATCHEWAN BY 00Z WEDNESDAY. AS THIS OCCURS...THE UPPER
RIDGING OVER THE PLAINS GETS PUSHED EAST ACROSS THE FORECAST
AREA. IN ADDITION...THE LEE TROUGHING TURNS INTO A COLD FRONT AND
REACHES THE SIOUX FALLS AREA BY 00Z WEDNESDAY. THE HEAT BUILDING UP
ACROSS THE DAKOTAS AND THE STRENGTHENING WINDS WILL ACCOMPANY THE
EASTWARD PROGRESS OF THE UPPER RIDGE. 850MB TEMPS AT 12Z THIS
MORNING SHOULD RANGE FROM 9-12C EAST TO WEST. BY 00Z THIS
EVENING...THEY ARE PROGGED TO CLIMB TO AT LEAST 14-17C IF NOT A
LITTLE WARMER. WITH INCREASING SOUTHERLY WINDS...DRY AIR AND PLENTY
OF SUN OUTSIDE OF MAYBE SOME CIRRUS...WE SHOULD HAVE NO PROBLEM
MIXING TO 850MB. GOING HIGHS OF MIDDLE 70S TO LOWER 80S REFLECT THIS
WELL. A SOUTHERLY BREEZE WILL HELP TO KEEP LOW TEMPERATURES IN THE
50S TONIGHT. FURTHER WARMING CONTINUES INTO TUESDAY WITH 850MB TEMPS
REACHING 20-22C BY 18Z...OR 1.5-2 STANDARD DEVIATIONS ABOVE NORMAL.
THERE ARE INDICATIONS OF INCREASE CIRRUS DURING THE AFTERNOON...BUT
MOST OF THE DAY SHOULD SEE PLENTY OF SUN. WINDS WILL BE STRONGER...
WITH SOUTHWEST SPEEDS OF 25 KT AT 925MB AND 35KT AT 850MB. THE
COMBINATION OF THESE WINDS...STILL PLENTY OF DRY AIR AND THE SUN
SHOULD PROPEL TEMPERATURES UP INTO THE MIDDLE 80S TO AROUND 90. WITH
THE WARM...DRY AIR AND INCREASING WINDS...THERE ARE SOME FIRE
WEATHER CONCERNS WHICH ARE DISCUSSED IN THE FIRE WEATHER AFD
SECTION.
TUESDAY NIGHT AND WEDNESDAY...UPPER RIDGING IS PROGGED TO STRENGTHEN
ACROSS THE OHIO VALLEY INTO THE EASTERN GREAT LAKES REGION DURING
THIS TIME. THIS IN TURN HELPS TO HOLD THE FORECAST AREA UNDER
SOUTHWEST FLOW ALOFT. WITH THE COLD FRONT THAT REACHED SIOUX FALLS
AT 00Z WEDNESDAY HAVING A NEAR SOUTHWEST TO NORTHEAST ORIENTATION...
CLOSE TO PARALLELING THE UPPER FLOW...THE SLOW EASTWARD PROGRESS
MODELS HAVE TRENDED TO THE PAST FEW DAYS MAKES SENSE. LOOKS LIKE THE
COLD FRONT MAY REACH ROCHESTER AROUND 12Z WEDNESDAY...THEN SLOWLY
CROSS THE FORECAST AREA BY 00Z THURSDAY. NO CONCERN EXISTS ABOUT THE
FRONT INITIATING PRECIPITATION AHEAD OF IT...DUE TO A DRY CAPPED
AIRMASS IN PLACE. HOWEVER...BEHIND THE FRONT THINGS ARE MORE
INTERESTING. FIRST IN THE 500MB PATTERN...MODELS SHOW A POTENT
SHORTWAVE DROPPING DOWN THE BACK SIDE OF THE DEEP SOUTH CENTRAL
CANADA TROUGH...REACHING EASTERN MONTANA LATE WEDNESDAY. AN 80-120
KT JET AT THE TROPOPAUSE IS PROGGED TO DEVELOP AHEAD OF THIS POTENT
SHORTWAVE INTO NORTHERN MINNESOTA AND ONTARIO. THIS PLACES SOUTHERN
MINNESOTA INTO NORTHWEST WISCONSIN UNDER UPPER LEVEL DIVERGENCE.
ALSO IN THE 500MB PATTERN THERE IS AN UPPER LOW CURRENTLY NEAR BAJA
CALIFORNIA WHICH MODELS SHEAR APART AND LIFT INTO SOUTHERN MINNESOTA
BY 00Z THURSDAY. THIS FEATURE WILL HELP PRODUCE SOME DPVA. LASTLY...
ON THE BACK/NORTHWEST SIDE OF THE FRONT...LOW TO MID LEVEL
FRONTOGENESIS IS PROGGED TO INCREASE THROUGH THE DAY WEDNESDAY. SO
PLENTY OF FORCING EXISTS BEHIND THE FRONT TO PRODUCE PRECIPITATION.
THIS LEAVES MOISTURE THE ONLY ISSUE...WHICH DOES NOT LOOK TO BE A
PROBLEM AS PRECIPITABLE WATER VALUES CLIMB TO 1.5 INCHES BEHIND THE
FRONT. THEREFORE...PRECIPITATION DEVELOPMENT BEHIND THE FRONT WILL
OCCUR. THERE IS A SHOT SOME OF THIS COULD GET INTO NORTHWESTERN
PORTIONS OF THE FORECAST AREA PER THE 10.00Z GFS...BUT OVERALL MODEL
CONSENSUS KEEPS THE BULK OF IT NORTH AND WEST OF THE AREA ON
WEDNESDAY. REGARDING TEMPERATURES...WITH THE WARM AIRMASS IN PLACE
AND A SOUTHERLY BREEZE PERSISTING...TUESDAY NIGHT SHOULD SEE LOWS
FROM THE MIDDLE 50S TO MIDDLE 60S. 850MB TEMPS ARE A LITTLE COOLER
ON WEDNESDAY...14-18C...BUT SUN THROUGH CIRRUS ALONG/AHEAD OF THE
FRONT SHOULD BRING HIGHS UP INTO THE LOW TO MID 80S. BEHIND THE
FRONTAL PASSAGE...INCREASING MID/HIGH CLOUDS AND POSSIBLE
PRECIPITATION WILL RESULT IN SLIGHTLY COOLER CONDITIONS.
WEDNESDAY NIGHT...GOOD CONSENSUS EXISTS FOR THIS PERIOD TO BE WET...
ESPECIALLY FOR THE NORTHWEST HALF OF THE FORECAST AREA. UPPER LEVEL
DIVERGENCE WILL SHIFT OVER THE FORECAST AREA...ALONG WITH THE LOW TO
MID LEVEL FRONTOGENESIS. THIS IS ALL RELATED TO THE DEEP SOUTH
CENTRAL CANADA TROUGH LIFTING OUT TO THE NORTHEAST...AND THE POTENT
SHORTWAVE IN MONTANA SHIFTING INTO THE DAKOTAS AND CLOSING OFF INTO
AN UPPER LOW. AGAIN...PLENTY OF MOISTURE EXISTS WITH PRECIPITABLE
WATER VALUES UP AROUND 1.5 INCHES OR 160 PERCENT OF NORMAL. GIVEN
THE EXCELLENT CONTINUITY AND CONSENSUS FOR PRECIPITATION IN THE
NORTHWEST HALF OF THE FORECAST AREA...HAVE RAISED PRECIPITATION
CHANCES THERE TO 80 OR HIGHER. SOME NEGATIVE EPV NOTED IN CROSS
SECTIONS THAT GETS INGESTED INTO THE FRONTOGENESIS CIRCULATION.
THIS NEGATIVE EPV SHOULD PRODUCE CONVECTIVE BANDING AND SOME
ISOLATED THUNDERSTORMS...DESPITE THE LACK OF ANY CAPE. WITH THE
CONVECTIVE NATURE AND HIGH PRECIPITABLE WATER...THE QPF AMOUNTS IN
THE 10.00Z GFS/NAM OF UPWARDS OF 1 INCH IN 6 HOURS IS CERTAINLY
POSSIBLE. COMBINATION OF GRADUAL COLD ADVECTION BEHIND THE FRONT
ALONG WITH PRECIPITATION WILL RESULT IN COOLER TEMPERATURES COMPARED
TO TUESDAY NIGHT. FOLLOWED A BLEND OF GUIDANCE FOR LOWS.
.LONG TERM...THURSDAY THROUGH SUNDAY NIGHT
311 AM CDT MON SEP 10 2012
10.00Z ECMWF/GFS/GFS ENSEMBLES ARE IN GOOD AGREEMENT THROUGH ABOUT
FRIDAY...THEN DIFFERENCES BEGIN TO SHOW UP. THE 10.00Z CANADIAN IS
A FAST OUTLIER TO START OFF WITH AS IT DOES NOT HAVE THE POTENT
SHORTWAVE OVER THE WESTERN DAKOTAS AT 12Z THURSDAY LIKE OTHER
MODELS. AS SUCH...THIS MODEL WAS FOR THE MOST PART DISCOUNTED.
GENERAL THEME FROM THE ECMWF/GFS/GFS ENSEMBLES IS THAT THE POTENT
SHORTWAVE OVER THE WESTERN DAKOTAS WILL COME CLOSE TO OR ACROSS THE
FORECAST AREA ON FRIDAY AS A CLOSED OFF UPPER LOW. ALL FORCING FOR
PRECIPITATION LOOKS TO REMAIN TO THE EAST OF THE UPPER LOW...WHERE
THE FRONTOGENESIS IS OCCURRING. ON THURSDAY...HIGH CONFIDENCE EXISTS
THAT THE SOUTHEASTERN HALF OF THE FORECAST AREA WILL SEE RAIN...AS
THE FRONTOGENESIS FROM WEDNESDAY NIGHT PUSHES EAST. RAISED
PRECIPITATION CHANCES IN THIS AREA TO 70. PRECIPITATION CHANCES THEN
LOWER THROUGH FRIDAY...BUT DONT COMPLETELY GO AWAY DUE TO THE UPPER
LOW NEARBY. TEMPERATURES WILL DEFINITELY BE COOLER. HOW COOL DEPENDS
ON EXACTLY WHERE THE RAIN SETS UP. IT IS POSSIBLE THAT HIGHS ON
THURSDAY COULD GET STUCK IN THE 50S WHERE IT RAINS...VERSUS MID 60S
TO AROUND 70 WHERE IT DOESNT. COOL AIR ASSOCIATED WITH THE UPPER
LOW SHOULD HOLD HIGHS DOWN IN THE MID 60S FOR FRIDAY.
BEYOND FRIDAY...THE FORECAST PRETTY MUCH REVOLVES AROUND THE UPPER
LOW. OVER THE PAST 24 HOURS OR SO...HAVE SEEN VARIOUS GFS AND ECMWF
MODEL RUNS HANDLE THE UPPER LOW DIFFERENTLY. EVEN WITH THE 10.00Z
RUNS...THE ECMWF TAKES IT SLOWLY EAST ACROSS IOWA AND ILLINOIS FROM
FRIDAY INTO SATURDAY WHILE THE GFS HAS IT HEADING UP INTO EASTERN
ONTARIO. THE 09.06Z GFS RUN HAD THE UPPER LOW ON SATURDAY STILL OVER
THE FORECAST AREA. AS SUCH...FORECAST CONFIDENCE BEYOND FRIDAY IS
LOW. GENERAL THEME...THOUGH...IS ANY RAIN SHOULD FOR THE MOST PART
BE EAST OF THE FORECAST AREA...WHICH IS WHAT THE CONSENSUS APPROACH
GIVES. BY THE TIME WE APPROACH SUNDAY...THERE ARE INDICATIONS OF A
DEEPENING CENTRAL CANADA TROUGH INTO THE NORTHERN ROCKIES. IF THIS
DOES OCCUR AS FORECAST...WE SHOULD SEE A WARM UP AS SOUTHERLY FLOW
PICKS UP AHEAD OF THE TROUGHING. THE TEMPERATURE FORECAST PLAYS THIS
IDEA WITH HIGHS CLIMBING BACK INTO THE LOW TO MID 70S FOR SUNDAY.
&&
.AVIATION...TODAY AND TONIGHT
610 AM CDT MON SEP 10 2012
BIGGEST CONCERN TODAY/TONIGHT IS THE REMNANT VALLEY FOG/SCT-BKN IFR
STRATUS AT/NEAR KLSE UNTIL ABOUT 14Z. SFC HIGH SLIPPING OFF TO THE
SOUTHEAST AND INCREASING PRESSURE GRADIENT WILL ERODE/LIMIT THE
BR/FG EARLY THIS MORNING. A DRY AIRMASS OVER THE AREA AND SOME WIND
WILL KEEP CONDITIONS VFR THRU THE REST OF TODAY/TONIGHT. PRESSURE
GRADIENT CONTINUES TO TIGHTEN OVER THE AREA THRU THE DAY...WITH
SOUTH WINDS OF 10-20KTS G20-30KTS BY THIS AFTERNOON. WINDS OVER THE
HIGHER TERRAIN/OPEN COUNTRY AREAS AND RIDGE-TOPS /KRST/KAUM/KCCY/
WILL TOWARD THE HIGHER END OF THE RANGE WITH THE VALLEY FLOORS
/KONA/KLSE/KOVS/ TOWARD THE LOWER END OF THE WIND SPEED RANGE.
GRADIENT WILL REMAIN TIGHT TONIGHT WITH SOUTH WINDS IN THE 10-15KT
RANGE OVERNIGHT...WHICH WILL KEEP THE VALLEY FOG THREAT TO A
MINIMUM. SOUTH WINDS WILL BE BRISK AGAIN ON TUE...15-25KT AND GUSTY.
&&
.CLIMATE...TUESDAY
340 PM CDT SUN SEP 9 2012
HIGH TEMPERATURES WILL CLIMB TO AROUND 90 DEGREES MAINLY NORTHWEST
OF A CHARLES CITY IOWA TO BLACK RIVER FALLS LINE ON TUESDAY. THE
RECORD HIGHS FOR THIS DATE ARE...
LA CROSSE WI - 97 IN 1897
MEDFORD WI - 95 IN 1900
ROCHESTER MN - 94 IN 1931
AUSTIN MN - 92 IN 1948
CHARLES CITY IA - 96 IN 2000
DECORAH IA - 97 IN 1895
&&
.FIRE WEATHER...TODAY AND TUESDAY
311 AM CDT MON SEP 10 2012
INCREASING SOUTH TO SOUTHWEST WINDS TODAY AND TUESDAY WILL BRING
WARMER AIR INTO THE REGION. SPEEDS ON THESE WINDS LOOK TO RANGE FROM
15 TO 25 MPH WITH GUSTS UP TO 35 MPH. WITH PLENTY OF SUNSHINE...GOOD
MIXING WILL OCCUR...BRINGING TEMPERATURES UP TO 75 TO 80 TODAY AND
85 TO 90 ON TUESDAY. DEWPOINTS ARE A LITTLE TRICKY...SINCE THE WIND
DIRECTION FAVORS A RETURN FLOW OF MOISTURE. HOWEVER...THE GULF OF
MEXICO DOES NOT OPEN UP FOR THE RETURN OF MOISTURE UNTIL AT LEAST
LATE TUESDAY. THEREFORE...DEWPOINTS WILL TAKE THEIR TIME COMING
UP...BEING COUNTERED DURING THE AFTERNOONS DUE TO MIXING. CURRENT
THINKING IS THAT RELATIVE HUMIDITIES ARE GOING TO END UP IN THE 25
TO 35 PERCENT RANGE...LOWEST IN WESTERN PORTIONS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA.
WITH THE DRYING LANDSCAPE/MATURING VEGETATION AND THE ABOVE WEATHER
CONDITIONS...CONCERN IS THERE FOR SOME FIRES. HOWEVER...THE RELATIVE
HUMIDITIES ARE JUST ABOVE THE CRITICAL 25 PERCENT THRESHOLD NEEDED
FOR A FIRE WEATHER RELATED HAZARD. IN ADDITION...FIRE WEATHER USERS
AFFECTED IN OUR FORECAST AREA ARE ALRIGHT WITHOUT ANY FIRE WEATHER
RELATED HAZARD AT THIS TIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
311 AM CDT MON SEP 10 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.......RIECK
CLIMATE........BOYNE
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
311 AM CDT MON SEP 10 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
311 AM CDT MON SEP 10 2012
MAIN FORECAST CONCERNS ARE ON THE WARMTH TODAY AND TUESDAY...THEN
WHEN PRECIPITATION ARRIVES FOR WEDNESDAY INTO WEDNESDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING COMING INTO BRITISH COLUMBIA AND THE PACIFIC
NORTHWEST...RIDGING ACROSS MUCH OF THE PLAINS INTO MANITOBA...AND
TROUGHING ALONG THE EAST COAST. SOME CIRRUS NOTED SPILLING OVER TOP
OF THE RIDGE INTO NORTHERN MINNESOTA. OTHERWISE...PLENTY OF
SUBSIDENCE UNDER THE UPPER RIDGE AS WELL AS DRY AIR RESULTING IN
CLEAR SKIES FROM THE CENTRAL PLAINS INTO THE FORECAST AREA.
REGARDING THE DRY AIR...GOES SOUNDER PRECIPITABLE WATER IMAGERY
SHOWED VALUES OF 0.3 TO 0.5 INCHES WHERE THE CLEAR SKIES ARE...OR
AROUND 50 PERCENT OF NORMAL. AT THE SURFACE...HIGH PRESSURE
STRETCHED FROM MISSOURI INTO LOWER MICHIGAN AND LEE TROUGHING WAS
PRESENT ALONG THE EAST SIDE OF THE ROCKIES. SOUTHERLY WINDS WERE
INCREASING OVER THE PLAINS INTO MINNESOTA...BOTH AT THE SURFACE AND
ALOFT. AT 850MB...PROFILER DATA SHOWED 40-50 KT SOUTHWEST WINDS
ACROSS THE DAKOTAS. THESE WINDS DOWNSLOPING OFF THE ROCKIES ARE
PRODUCING 22-27C 850MB TEMPS OVER THE DAKOTAS PER RAP ANALYSIS. OVER
THE FORECAST AREA...LIGHTER WINDS ASSOCIATED WITH THE SURFACE HIGH
ALLOWING THE TYPICAL COLD SPOTS TO DROP INTO THE UPPER 30S. ANY
VALLEY FOG THUS FAR HAS BEEN CONFINED TO THE WISCONSIN RIVER
VALLEY...AND EVEN THAT HAS NOT CONSISTENTLY STAYED IN PLACE.
TODAY THROUGH TUESDAY...MODELS ARE IN GOOD AGREEMENT SHOWING THE
UPPER TROUGHING COMING INTO BRITISH COLUMBIA DEEPENING AND SHIFTING
EAST TO SASKATCHEWAN BY 00Z WEDNESDAY. AS THIS OCCURS...THE UPPER
RIDGING OVER THE PLAINS GETS PUSHED EAST ACROSS THE FORECAST
AREA. IN ADDITION...THE LEE TROUGHING TURNS INTO A COLD FRONT AND
REACHES THE SIOUX FALLS AREA BY 00Z WEDNESDAY. THE HEAT BUILDING UP
ACROSS THE DAKOTAS AND THE STRENGTHENING WINDS WILL ACCOMPANY THE
EASTWARD PROGRESS OF THE UPPER RIDGE. 850MB TEMPS AT 12Z THIS
MORNING SHOULD RANGE FROM 9-12C EAST TO WEST. BY 00Z THIS
EVENING...THEY ARE PROGGED TO CLIMB TO AT LEAST 14-17C IF NOT A
LITTLE WARMER. WITH INCREASING SOUTHERLY WINDS...DRY AIR AND PLENTY
OF SUN OUTSIDE OF MAYBE SOME CIRRUS...WE SHOULD HAVE NO PROBLEM
MIXING TO 850MB. GOING HIGHS OF MIDDLE 70S TO LOWER 80S REFLECT THIS
WELL. A SOUTHERLY BREEZE WILL HELP TO KEEP LOW TEMPERATURES IN THE
50S TONIGHT. FURTHER WARMING CONTINUES INTO TUESDAY WITH 850MB TEMPS
REACHING 20-22C BY 18Z...OR 1.5-2 STANDARD DEVIATIONS ABOVE NORMAL.
THERE ARE INDICATIONS OF INCREASE CIRRUS DURING THE AFTERNOON...BUT
MOST OF THE DAY SHOULD SEE PLENTY OF SUN. WINDS WILL BE STRONGER...
WITH SOUTHWEST SPEEDS OF 25 KT AT 925MB AND 35KT AT 850MB. THE
COMBINATION OF THESE WINDS...STILL PLENTY OF DRY AIR AND THE SUN
SHOULD PROPEL TEMPERATURES UP INTO THE MIDDLE 80S TO AROUND 90. WITH
THE WARM...DRY AIR AND INCREASING WINDS...THERE ARE SOME FIRE
WEATHER CONCERNS WHICH ARE DISCUSSED IN THE FIRE WEATHER AFD
SECTION.
TUESDAY NIGHT AND WEDNESDAY...UPPER RIDGING IS PROGGED TO STRENGTHEN
ACROSS THE OHIO VALLEY INTO THE EASTERN GREAT LAKES REGION DURING
THIS TIME. THIS IN TURN HELPS TO HOLD THE FORECAST AREA UNDER
SOUTHWEST FLOW ALOFT. WITH THE COLD FRONT THAT REACHED SIOUX FALLS
AT 00Z WEDNESDAY HAVING A NEAR SOUTHWEST TO NORTHEAST ORIENTATION...
CLOSE TO PARALLELING THE UPPER FLOW...THE SLOW EASTWARD PROGRESS
MODELS HAVE TRENDED TO THE PAST FEW DAYS MAKES SENSE. LOOKS LIKE THE
COLD FRONT MAY REACH ROCHESTER AROUND 12Z WEDNESDAY...THEN SLOWLY
CROSS THE FORECAST AREA BY 00Z THURSDAY. NO CONCERN EXISTS ABOUT THE
FRONT INITIATING PRECIPITATION AHEAD OF IT...DUE TO A DRY CAPPED
AIRMASS IN PLACE. HOWEVER...BEHIND THE FRONT THINGS ARE MORE
INTERESTING. FIRST IN THE 500MB PATTERN...MODELS SHOW A POTENT
SHORTWAVE DROPPING DOWN THE BACK SIDE OF THE DEEP SOUTH CENTRAL
CANADA TROUGH...REACHING EASTERN MONTANA LATE WEDNESDAY. AN 80-120
KT JET AT THE TROPOPAUSE IS PROGGED TO DEVELOP AHEAD OF THIS POTENT
SHORTWAVE INTO NORTHERN MINNESOTA AND ONTARIO. THIS PLACES SOUTHERN
MINNESOTA INTO NORTHWEST WISCONSIN UNDER UPPER LEVEL DIVERGENCE.
ALSO IN THE 500MB PATTERN THERE IS AN UPPER LOW CURRENTLY NEAR BAJA
CALIFORNIA WHICH MODELS SHEAR APART AND LIFT INTO SOUTHERN MINNESOTA
BY 00Z THURSDAY. THIS FEATURE WILL HELP PRODUCE SOME DPVA. LASTLY...
ON THE BACK/NORTHWEST SIDE OF THE FRONT...LOW TO MID LEVEL
FRONTOGENESIS IS PROGGED TO INCREASE THROUGH THE DAY WEDNESDAY. SO
PLENTY OF FORCING EXISTS BEHIND THE FRONT TO PRODUCE PRECIPITATION.
THIS LEAVES MOISTURE THE ONLY ISSUE...WHICH DOES NOT LOOK TO BE A
PROBLEM AS PRECIPITABLE WATER VALUES CLIMB TO 1.5 INCHES BEHIND THE
FRONT. THEREFORE...PRECIPITATION DEVELOPMENT BEHIND THE FRONT WILL
OCCUR. THERE IS A SHOT SOME OF THIS COULD GET INTO NORTHWESTERN
PORTIONS OF THE FORECAST AREA PER THE 10.00Z GFS...BUT OVERALL MODEL
CONSENSUS KEEPS THE BULK OF IT NORTH AND WEST OF THE AREA ON
WEDNESDAY. REGARDING TEMPERATURES...WITH THE WARM AIRMASS IN PLACE
AND A SOUTHERLY BREEZE PERSISTING...TUESDAY NIGHT SHOULD SEE LOWS
FROM THE MIDDLE 50S TO MIDDLE 60S. 850MB TEMPS ARE A LITTLE COOLER
ON WEDNESDAY...14-18C...BUT SUN THROUGH CIRRUS ALONG/AHEAD OF THE
FRONT SHOULD BRING HIGHS UP INTO THE LOW TO MID 80S. BEHIND THE
FRONTAL PASSAGE...INCREASING MID/HIGH CLOUDS AND POSSIBLE
PRECIPITATION WILL RESULT IN SLIGHTLY COOLER CONDITIONS.
WEDNESDAY NIGHT...GOOD CONSENSUS EXISTS FOR THIS PERIOD TO BE WET...
ESPECIALLY FOR THE NORTHWEST HALF OF THE FORECAST AREA. UPPER LEVEL
DIVERGENCE WILL SHIFT OVER THE FORECAST AREA...ALONG WITH THE LOW TO
MID LEVEL FRONTOGENESIS. THIS IS ALL RELATED TO THE DEEP SOUTH
CENTRAL CANADA TROUGH LIFTING OUT TO THE NORTHEAST...AND THE POTENT
SHORTWAVE IN MONTANA SHIFTING INTO THE DAKOTAS AND CLOSING OFF INTO
AN UPPER LOW. AGAIN...PLENTY OF MOISTURE EXISTS WITH PRECIPITABLE
WATER VALUES UP AROUND 1.5 INCHES OR 160 PERCENT OF NORMAL. GIVEN
THE EXCELLENT CONTINUITY AND CONSENSUS FOR PRECIPITATION IN THE
NORTHWEST HALF OF THE FORECAST AREA...HAVE RAISED PRECIPITATION
CHANCES THERE TO 80 OR HIGHER. SOME NEGATIVE EPV NOTED IN CROSS
SECTIONS THAT GETS INGESTED INTO THE FRONTOGENESIS CIRCULATION.
THIS NEGATIVE EPV SHOULD PRODUCE CONVECTIVE BANDING AND SOME
ISOLATED THUNDERSTORMS...DESPITE THE LACK OF ANY CAPE. WITH THE
CONVECTIVE NATURE AND HIGH PRECIPITABLE WATER...THE QPF AMOUNTS IN
THE 10.00Z GFS/NAM OF UPWARDS OF 1 INCH IN 6 HOURS IS CERTAINLY
POSSIBLE. COMBINATION OF GRADUAL COLD ADVECTION BEHIND THE FRONT
ALONG WITH PRECIPITATION WILL RESULT IN COOLER TEMPERATURES COMPARED
TO TUESDAY NIGHT. FOLLOWED A BLEND OF GUIDANCE FOR LOWS.
.LONG TERM...THURSDAY THROUGH SUNDAY NIGHT
311 AM CDT MON SEP 10 2012
10.00Z ECMWF/GFS/GFS ENSEMBLES ARE IN GOOD AGREEMENT THROUGH ABOUT
FRIDAY...THEN DIFFERENCES BEGIN TO SHOW UP. THE 10.00Z CANADIAN IS
A FAST OUTLIER TO START OFF WITH AS IT DOES NOT HAVE THE POTENT
SHORTWAVE OVER THE WESTERN DAKOTAS AT 12Z THURSDAY LIKE OTHER
MODELS. AS SUCH...THIS MODEL WAS FOR THE MOST PART DISCOUNTED.
GENERAL THEME FROM THE ECMWF/GFS/GFS ENSEMBLES IS THAT THE POTENT
SHORTWAVE OVER THE WESTERN DAKOTAS WILL COME CLOSE TO OR ACROSS THE
FORECAST AREA ON FRIDAY AS A CLOSED OFF UPPER LOW. ALL FORCING FOR
PRECIPITATION LOOKS TO REMAIN TO THE EAST OF THE UPPER LOW...WHERE
THE FRONTOGENESIS IS OCCURRING. ON THURSDAY...HIGH CONFIDENCE EXISTS
THAT THE SOUTHEASTERN HALF OF THE FORECAST AREA WILL SEE RAIN...AS
THE FRONTOGENESIS FROM WEDNESDAY NIGHT PUSHES EAST. RAISED
PRECIPITATION CHANCES IN THIS AREA TO 70. PRECIPITATION CHANCES THEN
LOWER THROUGH FRIDAY...BUT DONT COMPLETELY GO AWAY DUE TO THE UPPER
LOW NEARBY. TEMPERATURES WILL DEFINITELY BE COOLER. HOW COOL DEPENDS
ON EXACTLY WHERE THE RAIN SETS UP. IT IS POSSIBLE THAT HIGHS ON
THURSDAY COULD GET STUCK IN THE 50S WHERE IT RAINS...VERSUS MID 60S
TO AROUND 70 WHERE IT DOESNT. COOL AIR ASSOCIATED WITH THE UPPER
LOW SHOULD HOLD HIGHS DOWN IN THE MID 60S FOR FRIDAY.
BEYOND FRIDAY...THE FORECAST PRETTY MUCH REVOLVES AROUND THE UPPER
LOW. OVER THE PAST 24 HOURS OR SO...HAVE SEEN VARIOUS GFS AND ECMWF
MODEL RUNS HANDLE THE UPPER LOW DIFFERENTLY. EVEN WITH THE 10.00Z
RUNS...THE ECMWF TAKES IT SLOWLY EAST ACROSS IOWA AND ILLINOIS FROM
FRIDAY INTO SATURDAY WHILE THE GFS HAS IT HEADING UP INTO EASTERN
ONTARIO. THE 09.06Z GFS RUN HAD THE UPPER LOW ON SATURDAY STILL OVER
THE FORECAST AREA. AS SUCH...FORECAST CONFIDENCE BEYOND FRIDAY IS
LOW. GENERAL THEME...THOUGH...IS ANY RAIN SHOULD FOR THE MOST PART
BE EAST OF THE FORECAST AREA...WHICH IS WHAT THE CONSENSUS APPROACH
GIVES. BY THE TIME WE APPROACH SUNDAY...THERE ARE INDICATIONS OF A
DEEPENING CENTRAL CANADA TROUGH INTO THE NORTHERN ROCKIES. IF THIS
DOES OCCUR AS FORECAST...WE SHOULD SEE A WARM UP AS SOUTHERLY FLOW
PICKS UP AHEAD OF THE TROUGHING. THE TEMPERATURE FORECAST PLAYS THIS
IDEA WITH HIGHS CLIMBING BACK INTO THE LOW TO MID 70S FOR SUNDAY.
&&
.AVIATION...
1145 PM CDT SUN SEP 9 2012
A DIFFICULT CHALLENGE WITH WHAT TO DO WITH POSSIBLE FOG IN THE RIVER
VALLEY AT KLSE. 7 DEGREE T/TD SPREAD AT 03Z GENERALLY FAVORS DENSE
FOG...AS DOES THE CLEAR SKIES AND LIGHT SFC-NEAR SFC WINDS. MODELS
CONTINUE TO POINT TO AN INCREASE IN WINDS ABOVE THE INVERSION BY
09Z...A CONSISTENT SIGNAL OVER THE PAST COUPLE DAYS. NOT CONVINCED
THIS IS SUPPORTED BY THE SYNOPTIC SETUP. EVEN IF THESE STRONGER
WINDS ARE REALIZED...THE INVERSION IS IN PLACE AND DON/T BELIEVE IT
WOULD HAVE AN IMPACT ON THE FG POTENTIAL.
MEANWHILE TDS ONLY RECOVERED 3 F THIS EVENING. A 5 TO 7 DEGREE
REBOUND WOULD HAVE INCREASED CONFIDENCE FOR 1/4SM FG. NAM12/RAP
BUFKIT SOUNDINGS REMAIN POOR WITH TDS...RAP STILL TOO MOIST AND
NAM12 TOO DRY AT 03Z. BOTH KEEP AT LEAST A 1 DEGREE T/TD SPREAD
THROUGH 12Z. IN ADDITION...THE SOUNDINGS GO FROM SUBSIDENT TO SOME
LIGHT UPWARD MOTION AFTER 09Z. SUBSIDENCE ALL NIGHT WOULD FAVOR
FOG.
WILL CONTINUE WITH THE BCFG FOR NOW. CONFIDENCE JUST SHAKY ENOUGH TO
HOLD OFF ON ADDING PREVAILING SUB 1SM AT THE MOMENT. CONDITIONS WILL
HAVE TO BE MONITORED VERY CLOSELY THROUGH DAYBREAK AND UPDATES MADE
AS NEEDED. THREAT IS STILL THERE FOR 1/4SM FG.
HIGH PRESSURE SHIFTS EAST ON MONDAY...WITH A TIGHT PRESSURE GRADIENT
RESULTING IN A BREEZY SOUTHERLY FLOW. SOME AFTERNOON MIXING SHOULD
RESULT IN GUSTS UP TO 30 MPH AT KRST.
&&
.CLIMATE...TUESDAY
340 PM CDT SUN SEP 9 2012
HIGH TEMPERATURES WILL CLIMB TO AROUND 90 DEGREES MAINLY NORTHWEST
OF A CHARLES CITY IOWA TO BLACK RIVER FALLS LINE ON TUESDAY. THE
RECORD HIGHS FOR THIS DATE ARE...
LA CROSSE WI - 97 IN 1897
MEDFORD WI - 95 IN 1900
ROCHESTER MN - 94 IN 1931
AUSTIN MN - 92 IN 1948
CHARLES CITY IA - 96 IN 2000
DECORAH IA - 97 IN 1895
&&
.FIRE WEATHER...TODAY AND TUESDAY
311 AM CDT MON SEP 10 2012
INCREASING SOUTH TO SOUTHWEST WINDS TODAY AND TUESDAY WILL BRING
WARMER AIR INTO THE REGION. SPEEDS ON THESE WINDS LOOK TO RANGE FROM
15 TO 25 MPH WITH GUSTS UP TO 35 MPH. WITH PLENTY OF SUNSHINE...GOOD
MIXING WILL OCCUR...BRINGING TEMPERATURES UP TO 75 TO 80 TODAY AND
85 TO 90 ON TUESDAY. DEWPOINTS ARE A LITTLE TRICKY...SINCE THE WIND
DIRECTION FAVORS A RETURN FLOW OF MOISTURE. HOWEVER...THE GULF OF
MEXICO DOES NOT OPEN UP FOR THE RETURN OF MOISTURE UNTIL AT LEAST
LATE TUESDAY. THEREFORE...DEWPOINTS WILL TAKE THEIR TIME COMING
UP...BEING COUNTERED DURING THE AFTERNOONS DUE TO MIXING. CURRENT
THINKING IS THAT RELATIVE HUMIDITIES ARE GOING TO END UP IN THE 25
TO 35 PERCENT RANGE...LOWEST IN WESTERN PORTIONS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA.
WITH THE DRYING LANDSCAPE/MATURING VEGETATION AND THE ABOVE WEATHER
CONDITIONS...CONCERN IS THERE FOR SOME FIRES. HOWEVER...THE RELATIVE
HUMIDITIES ARE JUST ABOVE THE CRITICAL 25 PERCENT THRESHOLD NEEDED
FOR A FIRE WEATHER RELATED HAZARD. IN ADDITION...FIRE WEATHER USERS
AFFECTED IN OUR FORECAST AREA ARE ALRIGHT WITHOUT ANY FIRE WEATHER
RELATED HAZARD AT THIS TIME.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
311 AM CDT MON SEP 10 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.......RIECK
CLIMATE........BOYNE
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS TUCSON AZ
910 PM MST TUE SEP 11 2012
.SYNOPSIS...AMPLE MOISTURE FOR SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH WEDNESDAY. A DRIER WESTERLY FLOW WILL LEAD TO MUCH LESS
THUNDERSTORM ACTIVITY THURSDAY INTO THE WEEKEND.
&&
.DISCUSSION...KEMX WSR-88D DETECTED SCATTERED 30-50 DBZ ECHOES
MOVING NEWD ACROSS WRN SANTA CRUZ/ERN PIMA COUNTIES AT 0405Z. THE
REST OF SE AZ WAS VOID OF PRECIP ECHOES AT THIS TIME. IR SATELLITE
IMAGERY AND SURFACE OBSERVATIONS INDICATED CLEAR SKIES ACROSS FAR
WRN PIMA COUNTY. ELSEWHERE...PARTLY CLOUDY TO MOSTLY CLOUDY SKIES
PREVAILED.
SHORTWAVE TROUGH WITH AXIS EXTENDING FROM CENTRAL NEVADA TO SRN
CALIFORNIA WILL MOVE SLOWLY EWD ACROSS THE SWRN CONUS THRU WED.
12/00Z NAM AND 12/00Z RUC HRRR PROG FAIRLY ROBUST QPF/S AS WELL AS A
FAIRLY LARGE AREA OF COMP REFLECTIVITY ECHOES THE REST OF TONIGHT
ACROSS MUCH OF SE AZ. BASED ON SATELLITE/RADAR TRENDS...BELIEVE
THESE PROGGED QPF/S AS WELL AS PRECIP ECHOES ARE OVERDONE.
HOWEVER...GIVEN THE AMPLE MOISTURE AS WELL AS THE AFOREMENTIONED
SHORTWAVE TROUGH AXIS STILL TO BE WEST OF THE AREA...WILL MAINTAIN
SCATTERED SHOWERS/TSTMS FROM TUCSON EWD AND A SLIGHT CHANCE OF
SHOWERS/TSTMS WEST OF TUCSON THE REST OF TONIGHT. ISOLATED TO
SCATTERED SHOWERS/TSTMS TO OCCUR WED MORNING.
THE OFFICIAL FORECAST WAS UPDATED TO REFLECT THE ABOVE SCENARIO.
PLEASE REFER TO THE PREVIOUS DISCUSSION BELOW FOR ADDITIONAL DETAIL.
&&
.PREV DISCUSSION...MID TO UPPER LEVEL DRYING...GENERALLY ABOVE
700MB...WILL COMMENCE STARTING WEDNESDAY AFTERNOON AS A WEST TO
NORTHWESTERLY FLOW DEVELOPS DUE TO RIDGING OVER THE WESTERN US.
SURFACE BASED MOISTURE MAY LINGER FOR A FEW MORE DAYS...BUT THE
DRYING AND WARMING ALOFT SHOULD GREATLY LIMIT PRECIP CHANCES.
THE MAIN CAVEAT TO THE DRY FORECAST IS THE EVENTUAL POSITION OF OUR
EXITING UPPER TROUGH. AS THE RIDGE BUILDS ACROSS THE WESTERN US...
THIS TROUGH MAY ONCE AGAIN CUT OFF FROM THE MEAN FLOW AND PARK OVER
NEW MEXICO THROUGH FRIDAY OR POSSIBLY SATURDAY BEFORE FINALLY
KICKING EAST OVER THE WEEKEND. IF THIS PANS OUT...THE FAR EASTERN
PORTION OF AZ MAY STILL SEE RAIN CHANCES. THE ECMWF MOS GUIDANCE
ALONG WITH THE MAV AND MET ALL PAINT CHANCE POPS OR GREATER ACROSS
PORTIONS OF COCHISE...GRAHAM AND GREENLEE COUNTIES FRIDAY MORNING.
SO I INCREASED RAIN CHANCES A FEW POINTS BUT LEFT ROOM TO INCREASE
FURTHER IF MODEL TRENDS CONTINUE.
OTHERWISE...ANOTHER WARMING TREND IS EXPECTED AS THE DRIER AIR MOVES
INTO SE ARIZONA. ANTICIPATE HIGH TEMPERATURES INCREASING TO NEAR OR
SLIGHTLY ABOVE NORMAL STARTING THURSDAY AND REMAIN FAIRLY PERSISTENT
THROUGH THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...SCT -TSRA/-SHRA MAINLY FROM KTUS EWD/SWD AND A SLIGHT
CHANCE OF -TSRA/-SHRA NW OF KTUS THRU WEDNESDAY EVENING OR 13/06Z.
WIND GUSTS BRIEFLY APPROACHING 35 KTS WITH THE STRONGEST TSRA
WEDNESDAY AFTERNOON. OTHERWISE...VFR CONDITIONS AND SURFACE WIND
GENERALLY LESS THAN 10 KTS THRU 13/06Z. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...SCATTERED THUNDERSTORMS THROUGH WEDNESDAY MAINLY
FROM TUCSON EASTWARD. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS EAST
OF TUCSON THURSDAY THROUGH THE WEEKEND. WITH DECREASING MOISTURE
THROUGH THE WEEKEND...EXPECT DAYTIME HIGH TEMPERATURES TO INCREASE
AND MINIMUM RELATIVE HUMIDITY VALUES TO DECREASE.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1110 PM MDT TUE SEP 11 2012
.UPDATE...
ISSUED AT 837 PM MDT TUE SEP 11 2012
00Z NAM/RUC AND 23Z HRRR SUPPORT PREVIOUS THINKING THAT WINDS
INITIALLY BEHIND THE COLD FRONT WILL GUST IN THE 30 TO 40 MPH
RANGE WITH SOME GUSTS TO 45 MPH POSSIBLE IN FAR EASTERN COLORADO
FOR A FEW HOURS. HAVE ALSO PULLED POPS FOR MOST OF THE NIGHT WITH
JUST A SMALL CHANCE ACROSS THE NORTHWEST CORNER OF THE AREA BY
12Z.
WILL CONTINUE TO MONITOR TRENDS AND ADJUST GRIDS AS NECESSARY.
UPDATE ISSUED AT 533 PM MDT TUE SEP 11 2012
WILL AWAIT 00Z DATA BEFORE MAKING AN UPDATE THIS EVENING. PRIMARY
CONCERN TONIGHT IS TIMING OF THE COLD FRONT AND POST FRONTAL WINDS
BEHIND IT.
AT PRESENT TIME 18Z/21Z DATA SUGGESTING WIND GUSTS OF 35 TO 45 MPH
WILL BE COMMON GENERALLY ALONG AND WEST OF THE CO/KS BORDER AFTER
03Z WHERE 3 HOUR PRESSURE RISES OF 5-7 MB EXPECTED. NOT SURE WE
WILL REACH 3 HOUR REQUIREMENT OF WIND GUSTS OF 45 MPH OR GREATER
FOR A WIND ADVISORY SO NO HIGHLITES EXPECTED PRESENTLY.
OTHER CONCERN IS THAT SLIGHT CHANCE/LOW CHANCE POPS THROUGH
MIDNIGHT MAY BE A BIT OVERDONE GIVEN THE BETTER MOISTURE AND JET
ENERGY REMAINS TO OUR WEST. FROM 06Z-12Z MAY NEED TO BUMP UP POPS
ACROSS THE FAR WEST/NORTHWEST WHERE THE MOISTURE AND JET ENERGY
FINALLY ARRIVES WHILE FURTHER EAST MAY NEED TO BRING POPS DOWN
GIVEN A DECREASING AVAILABILITY OF MOISTURE AND LIFT.
WILL FINE TUNE THE FORECAST ONCE THE 00Z DATA STARTS TO ARRIVE.
&&
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 136 PM MDT TUE SEP 11 2012
A TROUGH CAN BE SEEN ON WATER VAPOR OVER SOUTHERN NEVADA. THE LATEST
VISIBLE SATELLITE SHOWING A MOSTLY CLEAR SKY EAST OF THE ROCKIES.
THE 18Z SURFACE CHART SHOWS A TROUGH EXTENDING FROM EASTERN NEW
MEXICO ACROSS EASTERN COLORADO TO EASTERN SOUTH DAKOTA.
THE TROUGH OVER THE GREAT BASIN WILL MOVE EAST INTO THE ROCKIES
TONIGHT AND WEDNESDAY. THE SURFACE TROUGH WILL SHIFT SOUTHEAST
TONIGHT AND WEDNESDAY. A COLD FRONT WILL MOVE INTO THE PLAINS BEHIND
THE TROUGH LATE TONIGHT AND WEDNESDAY. POPS WILL INCREASE FROM
SLIGHT CHANCE FOR THUNDERSTORMS THIS EVENING NEAR THE TROUGH IN
EASTERN COLORADO TO CHANCES FOR SHOWERS AS INSTABILITY DECREASES
BEHIND THE FRONT OVERNIGHT. CHANCE POPS WILL BE ACROSS THE ENTIRE FA
WEDNESDAY AS BETTER RH AND DYNAMICS MOVE THROUGH. THE NORTHWEST FA
WILL HAVE LIKELY POPS WHERE MOISTURE IS MOST FAVORABLE. ONCE AGAIN
INSTABILITY IS LACKING SO WILL LIMIT THUNDER TO ISOLATED.
MIN TEMPERATURES WILL COOL DOWN TO THE MID 50S WEST TO THE LOWER 60S
EAST. MAX TEMPERATURES WEDNESDAY WILL RANGE FROM THE MID TO UPPER
60S BEHIND THE FRONT AND LOWER TO MID 70S NEAR THE FRONT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 210 PM MDT TUE SEP 11 2012
MAIN TROUGH AXIS IS STILL EXPECTED TO PASS OVER OUR CWA WED
NIGHT...WITH THE BEST LARGE SCALE ASCENT AND MOISTURE IN PLACE
ACROSS THE CWA WED EVENING. SHOWERS AND ISOLATED THUNDERSTORMS WILL
INCREASE IN COVERAGE OVER THE AREA THROUGH THE EVENING...AND THEN
MOVE EAST/SOUTHEAST WITH TROUGH. COVERAGE SHOULD THEN DECREASE
THROUGH THURSDAY MORNING...THOUGH A FEW LINGERING SHOWERS COULDNT BE
RULED OUT IN THE SOUTH THURSDAY AFTERNOON. WITH ALL AVAILABLE
GUIDANCE NOW IN GENERAL AGREEMENT ON TIMING/POSITION OF PRECIP I
FELT COMFORTABLE INCREASING POPS TO CATEGORICAL CATEGORY WED
EVENING ACROSS THE AREA. THERE IS STILL SOME SPREAD REGARDING
RAINFALL AMOUNTS...HOWEVER MUCH OF THE AREA SHOULD GET AT LEAST A
FEW TENTHS OF AN INCH OF RAIN...MORE DEPENDING ON WHERE THE
MODERATE BANDS OF PRECIP SET UP. TEMPERATURE OF THURSDAY SHOULD BE
IN THE 60S ACROSS MUCH OF THE AREA...WITH LOW 70S IN THE NORTH
WHERE CLEARING IS EXPECTED EARLIEST.
WITH A DRY/STABLE/COOL AIRMASS IN PLACE THU NIGHT WE COULD SEE ONE
OF THE COOLER NIGHTS SINCE LAST SPRING. CURRENT FORECAST HIGHS IN
THE UPPER 30S/LOW 40S ACROSS THE AREA IS IN LINE WITH WHAT OCCUR ED
LAST SAT NIGHT...HOWEVER WITH TD VALUES ADVERTISED TO DROP INTO THE
LOW 30S BY SOME GUIDANCE...COLDER TEMPERATURES ARE CERTAINLY
POSSIBLE.
DRY CONDITIONS AND MODERATING TEMPERATURES ARE EXPECTED FRIDAY INTO
NEXT WEEKEND AS A SHORTWAVE RIDGE BUILDS BACK OVER THE AREA.
TEMPERATURES WILL REMAIN BELOW NORMAL IN THE 70S FRIDAY AND NEAR
NORMAL IN THE LOW 80S SATURDAY. HIGHS ON SUNDAY MAY REACH THE UPPER
80S AT A FEW LOCATIONS WITH GOOD WAA AHEAD OF NEXT APPROACHING
SYSTEM. THE GOOD NEWS IS THAT THIS WOULD BE THE WARMEST DAY OF THE
ENTIRE FORECAST PERIOD...SO NO 100 DEGREE DAYS ON THIS FORECAST
CYCLE. ANOTHER UPPER LEVEL TROUGH IS EXPECTED TO MOVE ACROSS THE
NORTHERN PLAINS EARLY NEXT WEEK...BRINGING ANOTHER SHOT OF
PRECIPITATION AND COOLER TEMPERATURES BACK TO THE REGION. THERE IS
STILL A LOT OF UNCERTAINTY IN REGARDS TO THE TIMING/TRACK OF THIS
SYSTEM...HOWEVER IT DOES APPEAR TO SHOW A LOT OF SIMILARITIES TO THE
SYSTEM WE ARE EXPECTING THIS WEEK. I KEPT SLIGHT CHANCE/CHANCE POPS
IN PLACE MON AND MONDAY NIGHT WHERE CURRENT GUIDANCE IS TIMING
PRECIP WITH THIS SYSTEM.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1105 PM MDT TUE SEP 11 2012
VFR CONDITIONS WILL PERSIST THROUGH 22Z OR SO FOR BOTH TERMINALS.
DURING THIS TIME PERIOD NORTH TO NORTHEAST WINDS OF 20-25KTS WITH
GUSTS TO 35 KTS EXPECTED. AFTER 22Z CIGS WILL START TO DECREASE AS
LOW LEVEL MOISTURE INCREASES FROM THE WEST. MVFR/IFR CIGS EXPECTED
BY 00Z CONTINUING THROUGH 06Z. RAIN SHOWERS EXPECTED AROUND 00Z
WITH A STEADY RAIN AND SOME FOG/BR EXPECTED IN THE 01Z-05Z TIME
FRAME BEFORE TRANSITIONING BACK TO A MORE SHOWERY TYPE AS THE
FORCING AND MOISTURE SLOWLY MOVE EAST OF BOTH TERMINALS. THE
STRONG AND GUSTY NORTH TO NORTHEAST WINDS SHOULD TAPER OFF
SIGNIFICANTLY BY 00Z OR SHORTLY THEREAFTER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...99
SHORT TERM...FS
LONG TERM...DR
AVIATION...99
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1210 AM CDT WED SEP 12 2012
...UPDATED FOR THE 06Z TAF AND AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 104 PM CDT TUE SEP 11 2012
AN IMPRESSIVE CYCLONE WAS MATURING ALONG THE MANITOBA-SASKATCHEWAN
BORDER TODAY. RAP ANALYSIS SUGGESTED A COMPACT 110KT JET STREAK ON
THE IMMEDIATE SOUTHEAST SIDE OF THE CYCLONE OVER CENTRAL MANITOBA.
THE SURFACE WAS RESPONDING NICELY TO THIS WITH A 985MB SURFACE LOW
ANALYZED THROUGH SURFACE OBSERVATIONS. CLOSER TO HOME...A VERY
WEAK...SUBTLE MID LEVEL DISTURBANCE WAS MOVING ACROSS WESTERN KANSAS
INTO SOUTHERN NEBRASKA...WHICH WAS PRODUCING NOTHING MORE THAN A FEW
MID AND HIGH LEVEL CLOUDS ACROSS THE REGION. AT THE SURFACE...THE
COLD FRONT TIED TO THE CANADA STORM EXTENDED FROM NORTHEASTERN SOUTH
DAKOTA TO WESTERN NEBRASKA LATE THIS AFTERNOON. A FAIRLY TIGHT
PRESSURE GRADIENT AHEAD OF THIS FRONT (AND A LEE TROUGH ACROSS
EASTERN COLORADO AND FAR WESTERN KANSAS) RESULTED IN STRONG WINDS OF
20 TO 25 KNOTS ACROSS MUCH OF KANSAS...NEBRASKA...AND OKLAHOMA. A
VERY DRY ATMOSPHERE WAS PRESENT IN THE WARM (AND WINDY) SECTOR WITH
DEWPOINTS MAINLY IN THE UPPER 30S TO LOWER 40S ACROSS WESTERN KANSAS
AND NEBRASKA AND THE TEXAS PANHANDLE. AS SURFACE TEMPERATURES
CONTINUED TO RISE THROUGH THE LOWER 90S...RELATIVE HUMIDITY WAS
FALLING TO 15 TO 20 PERCENT...RESULTING IN WIDESPREAD NEAR CRITICAL
TO CRITICAL FIRE WEATHER CONDITIONS.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 313 PM CDT TUE SEP 11 2012
A COLLECTION OF SUBTROPICAL SHORTWAVE PERTURBATIONS OVER THE DESERT
SOUTHWEST WILL CONTINUE ITS MOVEMENT NORTHEAST THROUGH THE EVENING
AND TONIGHT...APPROACHING SOUTHWEST COLORADO AND NORTHEAST NEW
MEXICO BY DAYBREAK WEDNESDAY. MEANWHILE...THE SURFACE COLD FRONT
TIED TO THE CANADA STORM WILL REACH ROUGHLY A LAMAR CO-HILL CITY
KS-LINCOLN NE LINE BY DAYBREAK. THROUGH THE NIGHT...LOW LEVEL
PRESSURE GRADIENT WILL KEEP WINDS UP IN THE 15 TO 20 KNOT RANGE
THROUGH THE NIGHT...AND AS A RESULT TEMPERATURES WILL ONLY FALL INTO
THE MID TO UPPER 60S FOR LOWS FOR MOST AREAS OF SOUTHWEST AND WEST
CENTRAL KANSAS. SOME AREAS OF CENTRAL AND SOUTH CENTRAL KANSAS WILL
SEE TEMPERATURES BOTTOMING OUT ONLY IN THE 68 TO 70 DEGREE RANGE.
THERE IS A SUBSTANTIAL HIGH TEMPERATURE FORECAST CHALLENGE
WEDNESDAY...ESPECIALLY ACROSS WEST CENTRAL KANSAS (NORTHWEST OF A
GARDEN CITY TO LACROSSE LINE)...AS THE FRONT WILL INITIATE COLD AIR
ADVECTION FROM THE NORTH IN THESE AREAS BY MIDDAY. THE QUESTION IS
HOW MUCH DIRECT INSOLATION WILL OFFSET THE INITIAL COLD
ADVECTION...AS OVERALL CLOUD COVER SHOULD STILL BE CONFINED TO AREAS
FARTHER NORTH DURING THE DIURNAL MAXIMUM OF THE AFTERNOON. AM
LEANING MORE TOWARD A COMPROMISE OF THE NAM12 AND ECMWF FOR 18Z AND
00Z COLD FRONT TIMING AND ASSOCIATED SURFACE TEMPERATURES. A LOW
LEVEL THERMAL RIDGE WILL EXTEND NORTHEASTWARD AHEAD OF THE
FRONT...WHICH BY EARLY TO MID AFTERNOON SHOULD EXTEND FROM ROUGHLY
MEADE TO BUCKLIN TO PRATT. ALONG AND SOUTHEAST OF THIS
LINE...AFTERNOON TEMPERATURES SHOULD REACH THE LOWER TO MID 90S.
CONVERGENCE ALONG THE FRONT AND SURFACE LOW...ESPECIALLY SOUTH OF
DODGE CITY TO THE OKLAHOMA BORDER...WILL LIKELY BE ENOUGH TO
INITIATE ONE OR TWO THUNDERSTORMS IN ENVIRONMENT OF ABOUT 600 TO 900
J/KG OF SURFACE BASED CAPE IN THE HOT AIRMASS WITH LIMITED SURFACE
MOISTURE. WILL CARRY 20 POPS IN THIS AREA (SOUTHEAST OF ROUGHLY
MEADE TO BUCKLIN TO PRATT). THE MAIN PRECIPITATION EVENT TIED TO
THE 800-700MB FRONT WILL BE AFTER THE WEDNESDAY (DAY) PERIOD.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 241 PM CDT TUE SEP 11 2012
MEDIUM RANGE MODELS INDICATE AN UPPER LEVEL TROUGH OF LOW PRESSURE
MOVING EAST OUT OF THE COLORADO ROCKIES INTO THE WESTERN HIGH PLAINS
WEDNESDAY NIGHT AND THURSDAY BRINGING A REASONABLE CHANCE FOR PRECIP
TO PORTIONS OF WESTERN AND CENTRAL KANSAS EARLY IN THE PERIOD. A
COLD FRONT ATTENDANT TO A LARGER SCALE UPPER LEVEL TROUGH
TRANSITIONING EAST OUT OF THE NORTHERN PLAINS INTO THE GREAT LAKES
REGION, WILL PUSH SOUTHEAST INTO WESTERN KANSAS WEDNESDAY NIGHT
AHEAD OF THE UPPER LEVEL SHORTWAVE. AMPLE LOW LEVEL MOISTURE IS
EXPECTED TO POOL AHEAD OF THE APPROACHING FRONT WITH H85 DEWPOINTS
UP AROUND 10C IN CENTRAL AND WESTERN KANSAS AS INDICATED BY THE GEM,
GFS, AND ECMWF. HOWEVER, MODEL SOUNDINGS SHOW A FAIRLY WEAK FLOW
ALOFT ACROSS WESTERN KANSAS INITIALLY, BUT GRADUALLY INCREASING AS
AN UPPER LEVEL JET AXIS BEGINS TO FINALLY EDGE SOUTHEASTWARD ACROSS
NEBRASKA WITH A RIGHT ENTRANCE REGION JUST NOSING INTO KANSAS BY
EARLY THURSDAY MORNING. ADDITIONALLY, THE SOUNDINGS SHOW A LACK OF
STRONG INSTABILITY (CAPE) LATE WEDNESDAY NIGHT INTO EARLY THURSDAY
WITH NEAR SATURATED PROFILES. IN FACT, ALL MODELS INDICATE THE BEST
CHANCE FOR PRECIP IN ASSOCIATION WITH POST-FRONTAL H7 FRONTOGENESIS
BANDING LATE WEDNESDAY NIGHT INTO EARLY THURSDAY ACROSS MUCH OF
CENTRAL AND SOUTHWEST KANSAS. WILL KEEP 60 TO 70 POPS IN ACROSS
MUCH OF THE FORECAST AREA LATE WEDNESDAY NIGHT INTO EARLY THURSDAY.
TEMPERATURES WILL BE BELOW NORMAL THURSDAY IN WAKE OF THE COLD
FRONTAL PASSAGE EXPECTED LATE WEDNESDAY. ADDITIONALLY, INCREASED
LOW/MID LEVEL CLOUDS AND EXPECTED WIDESPREAD PRECIP EARLY TO MID DAY
THURSDAY WILL LIMIT CLIMBING TEMPERATURES. THE GEM, GFS, AND ECMWF
SHOW COOLER AIR FILTERING SOUTH INTO WESTERN KANSAS WITH H85
TEMPERATURES DROPPING DOWN TO AROUND 10C TO 12C ACROSS CENTRAL AND
SOUTHWEST KANSAS. AGAIN, WITH INCREASED CLOUDS AND LINGERING PRECIP
HIGHS COULD STRUGGLE TO REACH UP INTO THE 60S(F). THE BETTER CHANCE
FOR WARMER TEMPERATURES MAY COME ACROSS WEST CENTRAL AND EXTREME
SOUTHWEST KANSAS WHERE CLOUDS MAY POTENTIALLY SCATTER THURSDAY
AFTERNOON AS THE UPPER LEVEL SYSTEM PUSHES EAST. A GRADUAL WARMING
TREND IS THEN LIKELY THROUGH THE WEEKEND AS WEAK UPPER LEVEL RIDGING
BRIEFLY DEVELOPS ACROSS THE INTERMOUNTAIN WEST BEFORE BREAKING DOWN
SATURDAY AND SUNDAY. NEAR THE SURFACE, A GENERAL SOUTHEASTERLY FLOW
WILL DEVELOP FRIDAY AS SURFACE HIGH PRESSURE MIGRATES EAST INTO THE
OHIO RIVER VALLEY. MEANWHILE, MORE OF A SOUTHERLY COMPONENT WILL
TAKE OVER SATURDAY INTO SUNDAY AS A LEE SIDE TROUGH OF LOW PRESSURE
DEVELOPS IN EASTERN COLORADO HELPING TO ADVECT SLIGHTLY WARMER AIR
INTO THE REGION SUPPORTING THE WARMING TREND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1203 AM CDT WED SEP 12 2012
THE TAFS WILL REFLECT BREEZY SOUTH TO SOUTHEAST WINDS THROUGH
ABOUT 10Z ALONG WITH CLEAR SKIES. WINDS WILL BECOME SOUTHWEST
AROUND 14KTS TOWARD MORNING AS SURFACE TROUGH ADVANCES EAST FROM
COLORADO. A COLD FRONT IS COMING SOUTHEAST AND WILL SHIFT WINDS TO
THE NORTH-NORTHEAST AFTER 15 TO 16Z WEDNESDAY. THERE IS A SLIGHT
CHANCE FOR THUNDERSTORMS WEDNESDAY AFTERNOON, BUT THE BETTER CHANCE
APPEARS TO BE EAST OF ALL TAF SITES. THUS, CONVECTION WILL NOT BE
MENTIONED UNTIL LATER TAF ISSUANCES.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 55 65 48 72 / 80 80 20 0
GCK 52 67 47 72 / 80 60 10 0
EHA 52 66 49 74 / 80 70 10 0
LBL 53 66 49 72 / 70 70 20 0
HYS 53 67 45 72 / 70 50 10 0
P28 63 65 52 72 / 70 80 30 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...JJOHNSON
AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
300 AM CDT WED SEP 12 2012
.DISCUSSION...
QUITE A DIFFERENCE A DAY MAKES WITH EXPECTED TEMPERATURES TODAY AT
LEAST 20 DEGREES COOLER THAN YESTERDAY. CDFNT NOW PASSING ACROSS
THE METRO WITH TEMPS FALLING A GOOD 10 DEGREES IN AN HOUR OR TWO IN
WAKE OF FROPA. WITH BLANKET OF POSTFRONTAL CLOUDS DON`T EXPECT MUCH
IN THE WAY OF TEMPERATURE RECOVERY TODAY. COOLING IN WAKE OF FRONT
IS ALSO BEING AIDED BY VERY LOW DEW POINT DEPRESSIONS YEILDING HIGH
EVAPORATIVE COOLING ACROSS AREAS WHICH HAVE RECEIVED LIGHT PRECIP
OVERNIGHT.
-RA AND EVEN SOME ISOL THUNDER REMAINS IN A SW-NE BAND ACROSS SODAK
THEN ACROSS CENTRAL MN IN PLUME OF ELEVATED MOISTURE. PRECIP
AMOUNTS HAVE GENERALLY BEEN A FEW HUNDRETHS OF AN INCH...BUT ARND
.10 AT BENSON...APPLETON AND MADISON SO FAR. HRRR HAS BEEN DOING A
PRETTY GOOD JOB ON HANDLING THIS AREA OF PCPN WHICH HAS SOME SUPPORT
FROM RIGHT ENTRANCE REGION OF UPPER JET. INCREASED POPS FOR THE
MORNING ACROSS CENTRAL MN.
ANOTHER AREA OF SHWRS AND ISOL THUNDER HAS ALSO BEEN BEEN DEVELOPING
IN NW IA BACK INTO NEB. THIS AREA SHOULD CONTINUE TO DEVELOP DURING
THE DAY TODAY AS UPPER WAVE LIFTS OUT CO BACKING MID LEVEL WINDS AND
GENERATING FAVORABLE UPGLIDGE AROUND THE 305K SURFACE. INCREASED
POPS MAINLY ACRS S MN INTO THE KEAU AREA FOR LATER THIS MORNING AND
AFTN.
FOR THURSDAY A SHARP AND FAST MOVING UPPER TROF DIVES OUT OF THE
PRAIRIE PROVINCES OF CANADA TO NEAR NW CORNER MN BY 12Z AND INTO WI
BY 00Z THURSDAY. NOT MUCH MOISTURE AVAILABLE FOR PCPN...BUT
CONSIDERING PATH OF THIS FEATURE ACROSS AREA DURING THE DAYLIGHT AND
B24 500MB TEMPS...IT IS WORTHY OF A MENTION OF SLIGHT CHC POPS AND
ISOL THUNDER.
MODERATING TEMPERATURES OVER THE WEEKEND AS SOUTHERLY FLOW DEVELOPS
AHEAD OF NEXT IMPRESSIVE LOOKING COLD FRONT. FRONT COMES ACROSS
AREA SUNDAY NIGHT MONDAY BRINGING A CHANCE POPS AND SOME QUITE
CHILLY AIR AS 1000-500 MB THICKNESS DROPS TO 540DM ACROSS N MN.
LOOKING LIKE COOL START TO THE UPCOMING WEEK AS WE GET DEEP INTO NW
FLOW.
&&
.AVIATION.../06Z TAF ISSUANCE/
A STRONG COLD FRONT WILL CONTINUE TO MOVE THROUGH THE REGION
OVERNIGHT. SOUTHWESTERLY WINDS WILL BECOME NORTHWESTERLY AFTER
THE FRONT MOVES THROUGH. A FEW HIGH BASED SHOWERS WITH AN
OCCASIONAL LIGHTNING STRIKE ARE POSSIBLE AS WELL...BUT COVERAGE
WILL BE SCARCE AND ONLY INCLUDED VCSH IN THE TAFS. LATER TODAY
MORE WIDESPREAD SHOWERS WILL DEVELOP ALONG THE IA/WI/MN BORDER AND
COULD AFFECT KEAU.
KMSP...WINDS SHOULD SHIFT FROM SOUTHWEST TO NORTHWEST AROUND 05Z.
A FEW LIGHT SHOWERS ARE POSSIBLE AROUND 09Z...BUT BASES WILL BE
VERY HIGH AND NO VISBY RESTRICTIONS ARE EXPECTED. LATER THIS
AFTERNOON THE MAJORITY OF THE SHOWERS WILL BE SOUTH AND EAST OF
KMSP...SO HAVE LEFT OUT MENTION OF AFTERNOON SHOWERS IN THE TAFS.
/OUTLOOK FOR KMSP/
THURSDAY...VFR. WINDS NW AT 05G15KTS.
FRIDAY...VFR. WINDS NW AT 05KTS.
SATURDAY...VFR. WINDS SW AT 10KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BORGHOFF/BAP
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
407 AM CDT Wed Sep 12 2012
.DISCUSSION...
Today through Friday...
A band of weak elevated instability ahead of a surface cold front in
central Nebraska and northwest Iowa this morning has fired up a few
very light showers across the northwest corner of the forecast area.
The HRRR indicates these showers may persist just ahead of the
boundary for a few hours before mixing begins to eliminate the
instability, so have added a small chance of very light showers to
the far northwest through late morning. For the rest of the day,
above normal temperatures and breezy south winds can be expected
again, especially across the southwestern corner of the CWA. Surface
low pressure at the base of a deep trough over the northern Rockies
will push eastward into central Kansas today, resulting in the
tighter pressure gradient in our southwest, and could also provide
additional forcing needed to fire up some isolated convection mainly
west of the forecast area late this afternoon. As the main trough
dives to the southeast, the surface cold front will push through
southeast Nebraska and western Iowa, arriving at the northwest
corner of the CWA by 00z. Surface-based instability will build ahead
of the front this afternoon, which may result in isolated convective
initiation along the boundary as it enters the forecast area. Any
isolated development that occurs in central Kansas may also build
eastward during the evening, eventually merging with precipitation
along the cold front. However, surface-based convection will likely
not sustain after sunset, and the bulk of precipitation should occur
behind the surface front as the main wave moves through.
Although showers still look likely through Thursday as the main
trough makes southeastward progress across the CWA, precipitation
chances will decrease as the upper wave weakens and the best energy
transitions further east, towards the Great Lakes region. Have
gradually decreased the chance of precipitation from Thursday
morning through Friday, and also lowered precipitation amounts as
rainfall becomes more scattered. As the wave weakens, it also slows
across the region, so have slowed the southeastward progress of
rainfall chances, especially Thursday night and Friday. Lingering
showers should exit the region altogether by early Friday afternoon.
Temperatures will fall dramatically following cold frontal passage
on Thursday, especially with cloud cover and precipitation filling
in behind the surface front. Highs Thursday may only recover a few
degrees from overnight lows, especially in areas where the surface
front passes during the early morning. Temperatures will be slow to
recover this weekend as the midlevel boundary remains to our
southwest, keeping cooler air entrenched across the region.
Saturday through Tuesday...
A few model solutions break off the southwestern extent of the wave
on Friday, and keep a small disturbance over the Southern High
Plains from Friday night through Saturday. As the southwesterly jet
across the Texas panhandle increases Saturday, the lower pressure
deepens and begins to eject northeastward, possibly bringing
precipitation chances back into our south by early Sunday.
Afterward, another deep trough moves through the central U.S.,
bringing another cold front and additional chances of showers from
Monday morning through Tuesday. Temperatures will have little chance
to rebound back towards normal values early this week before the
next cold front comes through, which indicates mainly below normal
temperatures through the forecast period.
Laflin
&&
.AVIATION...
For the 06Z TAFs...winds continue to increase around 2000 ft AGL to
near 40 kt. This could cause some very minor LLWS concerns but with
near unidirectional flow near the surface and surface winds around 10
kts, do not expect LLWS to be problematic enough to mention it in the
TAFs. Otherwise expect a gradual increase in mid/high clouds through
the period ahead of a cold front that will approach the TAFs sites
toward 06Z Thurs.
06
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
356 AM CDT WED SEP 12 2012
.SHORT TERM...THROUGH FRIDAY NIGHT. CLEARLY THE PARAMOUNT ISSUE
OVER THE NEXT 72 HOURS CONCERNS PRECIP TRENDS DURING THE FIRST 24
HOURS...INCLUDING HOW MUCH RAIN WILL FALL AND WHEN THE MAJORITY OF
IT WILL START/END. ONE THING IS CERTAIN...ALTHOUGH THE MAJORITY OF
THE CWA WILL PROBABLY NOT MEASURE OVER 1 INCH...THIS IS STILL
LOOKING LIKE ONE OF THE MOST WIDESPREAD CHANCES FOR AT LEAST
0.30-0.90 THAT MUCH OF THE AREA HAS SEEN IN AWHILE...ESPECIALLY
NEAR/NORTH OF I-80. SECONDARY CONCERNS INCLUDE A VERY TRICKY TEMP
FORECAST TODAY.
07Z OBJECTIVE SURFACE ANALYSIS AND RADAR IMAGERY PLACES THE WELL-
ADVERTISED COLD FRONT ESSENTIALLY BISECTING THE CWA FROM SW-
NE...WITH THE LEADING EDGE ROUGHLY ALONG A BEAVER CITY-GRAND
ISLAND-COLUMBUS LINE AND SLOWLY BUT STEADILY ADVANCING SOUTHEAST
WITH TIME. THIS FRONT IS ANCHORED TO A 1005MB LOW ALONG THE
SOUTHERN CO/KS BORDER. IN THE WAKE OF THIS FRONT...NORTHERLY WIND
GUSTS HAVE INCREASED WELL INTO THE 25-35 MPH RANGE AT PLACES SUCH
AS ORD AND BROKEN BOW...WHILE AHEAD OF THE FRONT...SOUTHERLY GUSTS
OF AT LEAST 15-25 MPH CONTINUE IN MANY AREAS. THESE BREEZES...IN
TANDEM WITH CONSIDERABLE MID/HIGH CLOUDS HAVE KEPT OVERNIGHT TEMPS
WELL INTO THE 65-75 RANGE THUS FAR CWA-WIDE. ALOFT...WATER VAPOR
IMAGERY AND SHORT TERM MODEL DATA CONFIRMS BROAD WEST-SOUTHWEST
FLOW OVER THE CENTRAL PLAINS...WHILE WELL OFF TO THE NORTH A
POWERFUL VORT MAX OVER NORTHERN MANITOBA ANCHORS A TROUGH AXIS
TRAILING SOUTH INTO THE DAKOTAS/NORTHERN ROCKIES...AND WELL TO THE
SOUTHEAST OF THE CWA A BROAD RIDGE DOMINATES MUCH OF THE SOUTHEAST
CONUS.
STARTING OFF WITH THE EARLY MORNING PERIOD THROUGH SUNRISE...THE
MOST IMMEDIATE ISSUE IS THE RECENT DEVELOPMENT OF ISOLATED TO
SCATTERED SHOWER/FAIRLY WEAK THUNDERSTORM ACTIVITY MAINLY ACROSS
THE FAR NORTHEAST CWA...BUT ALSO STARTING UP OVER SOUTHWEST AND
SOUTHEAST NEB ZONES AS WELL. THIS SOMEWHAT UNEXPECTED PRE-DAWN
FLARE UP WAS NOT WELL CAPTURED BY MOST MODELS...BUT HAS BEEN
SUGGESTED FOR THE LAST SEVERAL HOURLY RUNS OF THE HRRR.
BASICALLY...THIS ACTIVITY SEEMS BEST TIED TO THE WARM AIR/THETA-E
ADVECTION ZONE NEAR AND JUST AHEAD OF THE 850MB COLD FRONT SLICING
INTO THE CWA...AND WITHIN THE AXIS OF A 45-55KT 850MB LOW LEVEL
JET. SPC HOURLY MESO- ANALYSIS ALONG WITH THE 06Z NAM INDICATES
THAT EVEN PEA SIZE HAIL SHOULD BE HARD TO COME BY GIVEN ELEVATED
MUCAPE IN THE 850-700MB LAYER AVERAGING NO MORE THAN 100-200 J/KG.
WILL MAKE A LAST MINUTE DECISION BEFORE FORECAST ISSUANCE
REGARDING HOW TO HANDLE THIS PRE-DAWN ACTIVITY IN THE GRIDS.
TURNING TO THE DAYTIME 12Z-00Z PERIOD...GENERALLY STUCK FAIRLY
CLOSELY TO THE THE THEME OF THE PREVIOUS FORECAST...BUT DUE TO
SOME UNCERTAINTY IN THE TIMING DETAILS OPTED TO NOT SPLIT THE
DAYTIME POP/WEATHER GRIDS INTO MORE THAN TWO 6-HOUR BLOCKS AT THIS
TIME. DESPITE THE EARLY MORNING ACTIVITY ONGOING OUT THERE...WANT
TO EMPHASIZE THAT THE MAJORITY OF THE CWA...ESPECIALLY THE
SOUTHEAST 2/3 WILL LIKELY SEE VERY LITTLE IF ANY MEASURABLE
RAINFALL THROUGH THE DAYTIME HOURS. STARTING WITH THE MORNING
12Z-18Z BLOCK...WILL LEAN TOWARD THE HRRR SUGGESTION THAT MOST OF
THIS PRE-DAWN WARM AIR ADVECTION DRIVEN CONVECTION WILL EXIT EAST
OF THE CWA OR AT LEAST DIMINISH IN COVERAGE BY SUNRISE OR SHORTLY
AFTER. THIS LEAVES THE MAIN FOCUS FOR MORNING PRECIPITATION ACROSS
FAR NORTHWEST PORTIONS OF THE CWA IN CLOSEST PROXIMITY TO THE
SOUTHEAST-ADVANCING MID LEVEL FRONTOGENETIC ZONE ALIGNED WITHIN
THE ENTRANCE REGION OF A 80-100KT 300MB JET STREAK RUNNING FROM
THE DAKOTAS INTO QUEBEC. AT LEAST FOR NOW...KEPT POPS DURING THE
12Z-18Z TIME FRAME BELOW LIKELY TERRITORY...BUT WITH 30-50 POPS
ACROSS THE NORTHWEST HALF TAPERING DOWN TO SLIGHT CHANCE SPRINKLE
WORDING ACROSS THE SOUTHEAST. FOR THE AFTERNOON 18Z-00Z
BLOCK...MAY HAVE NOT GONE HIGH ENOUGH WITH POPS GIVEN LATEST MODEL
TRENDS INCLUDING 06Z NAM...BUT HAVE AT LEAST 40-60 POPS GOING
ACROSS MUCH OF THE NORTHWEST HALF OF THE CWA...AND 70S-90S FAR
NORTH. MOST OF THE RAIN WILL BE TIED TO THE EXACT PLACEMENT OF THE
FAIRLY NARROW FRONTOGENETIC BAND...RESULTING IN A SLOWLY ADVANCING
BUT SHARP CUTOFF FROM STEADY LIGHT/MODERATE RAINFALL TO NOTHING.
KEPT THUNDER WORDING AS ISOLATED THROUGH THE DAY...AS EVEN MODEST
ELEVATED INSTABILITY SHOULD GRADUALLY DECREASE WITH TIME...AND ANY
RISK FOR MARGINALLY STRONG STORMS NEAR THE ACTUAL SURFACE COLD
FRONT DURING THE AFTERNOON/EARLY EVENING SHOULD REMAIN AT LEAST
1-2 COUNTIES SOUTH/SOUTHEAST OF OUR KS ZONES ACROSS THE TOP/ICT
CWA/S. TURNING TO OTHER ELEMENTS...HIGH TEMPS WILL BE VERY TRICKY
DAYS WITH MOST AREAS SEEING STEADY/SLOWLY FALLING TEMPS BEHIND THE
COLD FRONT. TOOK A BEST STAB THAT ENDED UP CLOSE TO PREVIOUS
FORECAST...WITH DAYLIGHT HIGHS RANGING FROM MID 60S FAR NORTHWEST
TO LOW-MID 70S TRI-CITIES AREA AND UPPER 80S FAR SOUTHEAST.
HOWEVER...ACTUAL HOURLY TEMPS ACROSS MUCH OF THE NORTHWEST 1/2 OF
THE CWA THIS AFTERNOON WILL ONLY BE IN THE 50S/60S...SO THE HIGH
TEMP GRID WILL BE A BIT MISLEADING. AS FOR SURFACE WIND
SPEEDS...ANTICIPATE SPEEDS TO AVERAGE AT LEAST 5 MPH BELOW
ADVISORY LEVELS...BUT AS THE FRONT PUSHES IN SHOULD EASILY SEE
SUSTAINED SPEEDS OF 20-25 MPH AND GUSTS UP TO AROUND 35 MPH AND
EVEN AS HIGH AS 40 MPH ON A HIT AND MISS BASIS.
TONIGHT...THIS IS STILL LOOKING LIKE THE MAIN EVENT FOR MOST OF
THE CWA...ESPECIALLY THE SOUTHEAST 2/3...AS THE STRENGTHENING MID
LEVEL FRONTOGENETIC BAND SLIDES SOUTHEAST OVER THE AREA...AND INDUCES
AN INCREASINGLY ORGANIZED BAND OF STEADY LIGHT TO MODERATE AND
POTENTIALLY BRIEFLY HEAVY RAIN. SPLIT THE POP/WEATHER GRIDS INTO
6-HOUR BLOCKS...BUT AT LEAST TOUCHED ALL AREAS SOUTH OF AN ELWOOD-
GRAND ISLAND-FULLERTON LINE WITH 80-90 POPS AT SOME POINT...WITH
LESSER CHANCES TAPERING OFF ACROSS NORTHWEST ZONES AS THE NIGHT
WEARS ON AND PLACES LIKE ORD/GOTHENBURG LIKELY COMPLETELY DONE
WITH PRECIP WELL BEFORE MIDNIGHT. TEMP-WISE...LOWERED LOWS ROUGHLY
3 DEGREES FROM PREVIOUS PER LATEST GUIDANCE...RANGING FROM MID 40S
NORTHWEST TO LOW 50S SOUTHEAST.
THURSDAY...LEFT 20-60 POPS GOING IN THE MORNING BLOCK FOR AREAS
GENERALLY SOUTH OF A PHILLIPSBURG-GENEVA LINE...BUT THE LATEST 06Z
NAM WOULD SUGGEST THAT VIRTUALLY THE ENTIRE CWA MAY BE PRECIP FREE
BY SUNRISE AS IT MOVES THE MID LEVEL BANDING OUT FASTER THAN
PREVIOUSLY ADVERTISED. NO MATTER WHAT...THE ENTIRE CWA WILL MOST
CERTAINLY BE DRY BY THE AFTERNOON HOURS...WITH MOSTLY CLEAR SKIES
INVADING FROM NORTH TO SOUTH AS THE DAY WEARS ON. ASSUMING THAT AT
LEAST A FEW HOURS OF SUNSHINE MATERIALIZES...ESPECIALLY NORTHERN
AREAS SHOULD WARM FAIRLY EFFICIENTLY. NUDGED UP HIGHS 1-3 DEGREES
IN MOST AREAS...WITH MOST NEB ZONES IN THE 71-74 RANGE AND FAR
SOUTHEAST ZONES MORE SO 69-71 WHERE CLOUDS WILL LINGER THE
LONGEST.
BEFORE MOVING ON TO THE DRY LATTER PART OF THE SHORT TERM
PERIOD...A FEW COMMENTS ABOUT RAINFALL AMOUNTS DURING THE NEXT 24-30
HOURS. TAKING LATEST BLEND OF MODEL CONSENSUS ALONG WITH HPC
GUIDANCE...AM NOW ADVERTISING WIDESPREAD QPF RANGING FROM
0.40-0.90 ACROSS THE MAJORITY OF THE CWA...WITH THE BEST POTENTIAL
FOR HIGHER AMOUNTS IN THE 1 INCH TO 1.4 RANGE TARGETING AREAS
SOUTHEAST OF A YORK TO OSBORNE LINE.
THURS NIGHT...COOL HIGH PRESSURE SETTLES INTO THE REGION...AND
ALTHOUGH WET GROUND SHOULD MITIGATE A SHARP TEMP DROP...KEPT LOWS
ON THE CHILLY SIDE AND CLOSE TO PREVIOUS FORECAST WITH MOST AREAS
IN THE 40-45 RANGE...AND EVEN SOME UPPER 30S NOW IN FAVORED COLDER
SPOTS SUCH AS VALLEY/WESTERN DAWSON COUNTIES. UNLESS THINGS TREND
ANOTHER 2-4 DEGREES COLDER...SHOULD BE FREE FROM EARLY SEASON
FROST CONCERNS.
FRIDAY IS LOOKING QUITE PLEASANT OVERALL WITH LIGHT BREEZES AS THE
SURFACE RIDGE AXIS SLOWLY SLIDES EAST...ALONG WITH PLENTY OF
SUNSHINE AS MID LEVEL RIDGING EXTENDS EAST OUT OF THE CENTRAL
ROCKIES. KEPT HIGHS SIMILAR TO PREVIOUS FORECAST WITH MOST AREAS
73-76...ALTHOUGH COULD SEE SOME AREAS A FEW DEGREES HIGHER THAN
THIS PER LATEST 06Z NAM TRENDS.
FRIDAY NIGHT...ANY PRECIP ASSOCIATED WITH A SOUTHERN STREAM WAVE
SHOULD REMAIN NO CLOSER THAN THE KS/OK BORDER AREA...PAVING THE
WAY FOR ANOTHER MAINLY CLEAR NIGHT AS LIGHT BUT STEADY SOUTH WINDS
BECOME ESTABLISHED. CHANGED LOWS LITTLE WITH MAINLY MID-UPPER 40S.
.LONG TERM...SATURDAY THROUGH TUESDAY. DRY WEATHER IS EXPECTED OVER
THE WEEKEND AND THEN THERE IS A CHANCE OF THUNDERSTORMS ON MONDAY
AS A COLD FRONT TRACKS ACROSS THE PLAINS. HIGH TEMPERATURES WILL BE
VERY PLEASANT THIS WEEKEND WITH HIGHS ON SATURDAY IN THE MID 70S AND
THEN AROUND 80 FOR MOST AREAS ON SUNDAY. TEMPERATURES WILL COOL
BEHIND THE FRONT ON MONDAY FALLING BACK INTO THE UPPER 60S TO LOWER
70S AND SHOULD REMAIN CLOSE TO THAT ON TUESDAY.
THE UPPER LEVEL PATTERN WILL BE FAIRLY ZONAL OVER THE WEEKEND AND
THEN AN UPPER TROUGH WILL SKIRT THROUGH THE NORTHERN PLAINS ON
MONDAY AND INTO THE GREAT LAKES BY TUESDAY. MOST OF THE DYNAMICS
ASSOCIATED WITH THIS SYSTEM SHOULD BE WELL NORTHEAST OF OUR FORECAST
AREA THUS LIMITING OUR PRECIPITATION CHANCES. CONSALL SEEMS VERY
OVERDONE WITH POPS IN THE 50 TO 60 PERCENT RANGE ON MONDAY. THE NEW
00Z ECMWF CAME IN DRY. OUR PREVIOUS FORECAST WAS ONLY CALLING FOR
SLIGHT POPS AT AROUND 20 PERCENT. WILL INCREASE POPS INTO THE LOW
END CHANCE CATEGORY AT AROUND 30 PERCENT...BUT NOT WILLING TO GO
HIGHER AT THIS POINT IN TIME GIVEN THE NORTHERN TRACK OF THE UPPER
DYNAMICS AND LACK OF SUPPORT IN THE LATEST 00Z ECMWF. THIS SHOULD BE
A QUICK HITTING SYSTEM WITH THE SFC HIGH ALREADY LOCATED EAST OF US
BY TUESDAY ALLOWING FOR A RETURN OF WEAK SOUTHERLY FLOW AND DRY
WEATHER. LATEST MODEL RUNS TONIGHT HAVE BEEN KEEPING THE
INSTABILITY ASSOCIATED WITH THE MONDAY SYSTEM ACROSS KANSAS AND WILL
JUST BE CALLING FOR RAIN SHOWERS OVER MOST NEBRASKA ZONES GIVEN THE
LACK OF INSTABILITY FOR THUNDERSTORMS. WILL CONTINUE TO KEEP A
MENTION OF ISOLATED THUNDERSTORMS SOUTH OF A HEBRON TO ALMA LINE.
&&
.PREV DISCUSSION... /ISSUED 100 AM CDT WED SEP 12 2012/
AVIATION...06Z KGRI TAF. A STRONG COLD FRONT WILL PASS THROUGH
KGRI JUST PRIOR TO DAWN AND RESULT IN A WIND SHIFT FROM SOUTH
SOUTHEAST TO NORTHEAST. NORTHEAST WINDS WILL QUICKLY GAIN STRENGTH
DURING THE DAY AND COULD GUST TO OVER 35 MPH AT TIMES FROM MID
MORNING THROUGH LATE AFTERNOON. MOST OF THE MORNING SHOULD BE DRY
WITH INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS AS WE HEAD
THROUGH THE AFTERNOON. RAIN WILL BE MOST LIKELY AT KGRI BETWEEN 5
PM AND 11 PM THIS EVENING WHEN OVER A HALF INCH OR RAIN COULD FALL.
THERE COULD BE A FEW CLAPS OF THUNDER BUT NOTHING STRONG OR
SEVERE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM/AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
245 AM CDT WED SEP 12 2012
.DISCUSSION...
COLD FRONT EXTENDED FROM NORTHWEST IOWA ACROSS NORTHEAST NEBRASKA
INTO SOUTH CENTRAL NEBRASKA ALONG A KSUX TO KEAR LINE AT 07Z.
SCATTERED SHOWERS AHEAD OF THE FRONT HAVE BECOME MORE NUMEROUS
DURING THE PAST HOUR OVER SOUTHEAST NEBRASKA INTO SOUTHWEST IOWA.
00Z GFS AND 04Z HRRR APPEAR TO BE SIMILAR IN HAVING THE FRONT NEAR
A KOMA TO KHJH LINE BY 12Z...A BIT FASTER THAN THE 00Z NAM.
WILL ADD CHANCE OF SHOWERS AND ISOLATED THUNDER TO AREAS SOUTH OF
THE FRONT THIS MORNING BASED ON RADAR TRENDS AND SHORT RANGE
MODELS. WILL ALSO LIKELY TREND HIGHS TODAY TOWARD THE SOMEWHAT
COOLER GFS GUIDANCE BASED ON FASTER TIMING OF THAT MODEL.
OTHERWISE...STILL LOOKS GOOD FOR WIDESPREAD RAIN ACROSS MUCH OF
THE AREA TONIGHT WITH SYSTEM MOVING OUT OF SOUTHEAST AREAS
THURSDAY MORNING. FAIR AND DRY AFTER THAT WITH COOLER TEMPERATURES
HANGING AROUND FOR A CHANGE.
IN THE EXTENDED...AREA REMAINS UNDER THE INFLUENCE OF COOLER
NORTHWEST FLOW WITH ANOTHER STRONG TROUGH MOVING THROUGH THE
REGION EARLY NEXT WEEK. STILL SOME CHANCE OF SHOWERS WITH COLD
FRONT ON MONDAY WITH LOW POPS MAINTAINED FOR THAT PERIOD. SOME
DIFFERENCES BETWEEN THE GFS AND EURO IN HANDLING THIS FASTER FLOW
SO WILL HAVE TO SEE HOW CONSISTENT FUTURE MODEL RUNS BEHAVE.
&&
.AVIATION...
06Z TAFS FOR KOFK...KOMA...KLNK.
WILL LEAVE MENTION OF LOW LEVEL WIND SHEAR IN THE KOMA AND KLNK
TAFS OVERNIGHT AS 850MB WINDS ARE FORECAST AROUND 35 TO 45KTS WITH
DECREASING SFC SPEEDS. A COLD FRONT WILL MOVE THRU THE SITES
DURING THE TAF PERIOD. FRONT WILL BE OVER KOFK IN FIRST FEW HOURS
WITH POST FRONTAL SHOWERS EXPECTED TO DEVELOP BY 18Z. FRONT WILL
BE THRU KOMA AND KLNK AROUND 18Z WITH POST FRONTAL SHOWERS
EXPECTED BY LATE AFTERNOON/EARLY EVENING. TIGHT GRADIENT BEHIND
THE FRONT WILL CREATE GUSTY NORTHEAST WINDS INITIALLY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
FOBERT/KERN
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
123 AM EDT WED SEP 12 2012
.SYNOPSIS...
FAIR WEATHER WILL PREVAIL THROUGH FRIDAY AS CANADIAN HIGH PRESSURE
SETTLES INTO THE REGION. AN APPROACHING COLD FRONT MAY BRING A FEW
SHOWERS OVER THE WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 11:00 PM TUESDAY...RIDGING SFC AND ALOFT TO DOMINATE THE ILM
CWA OVERNIGHT. SUBSIDENCE IN THE MID-LAYERS TO PREVENT ANY VERTICAL
DEVELOPMENT WITH THE CU/SC THAT DEVELOPS OVER THE ADJACENT ATLANTIC
WATERS AND SPORADICALLY MOVES ONSHORE DURING THIS PERIOD. THE NE-E
FLOW IN THE LOWER LEVELS WILL FORCE/LIFT WHAT MOISTURE THAT IS
AVAILABLE UPWARDS...WITH OROGRAPHIC LIFT AIDING ANY CU/SC
DEVELOPMENT WELL INLAND WITHIN THE ILM CWA. WILL GO WITH MOSTLY
CLEAR TO PTLY CLOUDY FOR SKY CONDITIONS TONIGHT. HRRR INDICATES
SPOTTY PCPN OR ISOLATED SHRA TO DEVELOP OVER THE ADJACENT
WATERS...AND PUSH ONSHORE BEFORE DISSIPATING ALTOGETHER. FOG
ALGORITHM PORTRAITS PATCHY TO AREAS OF FOG DEVELOPMENT FOR A SHORT
4-6 HR WINDOW ENDING/DISSIPATING BY 8-9 AM WEDNESDAY.
DRY AND RELATIVELY COOL WEATHER TO CONTINUE THROUGHOUT THE NEAR TERM
AS CANADIAN HIGH PRESSURE CENTERED ACROSS THE MID-ATLANTIC STATES TO
MARTHAS VINEYARD WHICH EVIDENTLY MAINTAINS A STEADY BUT LIGHT NE-E
FLOW ESPECIALLY FELT ACROSS THE COASTAL CAROLINAS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 300 PM TUESDAY...FALL LIKE WEATHER WILL CONTINUE THROUGH MID
WEEK AS CANADIAN HIGH PRESSURE SETTLES DOWN OVER THE SOUTHEAST
WHILE SHIFTING SLOWLY EAST. AS THE CENTER SLIPS OFF THE NEW
ENGLAND COAST...IT WILL CONTINUE TO RIDGE DOWN INTO THE CAROLINAS.
THIS WILL HELP VEER WINDS AROUND THROUGH THE PERIOD TO THE
NORTHEAST WED INTO THURS AND EAST BY END OF THE PERIOD WHICH WILL
PRODUCE A SLIGHT INCREASE IN MOISTURE COMING FROM THE ATLANTIC
WATERS. AN OVERALL RISE IN MOISTURE WILL BRING PCP WATER VALUES
FROM CLOSE TO A HALF INCH WED TO OVER AN INCH BY LATE THURS IN
MOISTURE COMING IN FROM THE E-NE. THEREFORE EXPECT SUNNY WEATHER
ON WED BUT SHOULD SEE MORE IN THE WAY OF CU DEVELOPMENT THURS
AFTERNOON ESPECIALLY ALONG SEA BREEZE BOUNDARY AND MAINLY OVER
NORTH CAROLINA ZONES. MOISTURE PROFILES AND SOUNDING DATA SHOW
MOISTURE LOCKED IN BELOW INVERSION REACHING UP TO 90% IN THE 2-4K
FT LEVEL ON THURS. EASTERLY FETCH OF MOISTURE MAY HELP TO PRODUCE
SOME FOG OR LOW STRATUS ON FRI IN THE EARLY MORNING CLOSER TO THE
COAST.
IN THE MID TO UPPER LEVELS THE RIDGE BECOMES MORE PRONOUNCED OVER
THE EAST COAST...BUT GETS SQUEEZED OUT BY END OF PERIOD BY BACK
BUILDING TROUGH OVER THE ATLANTIC AND TROUGH DIGGING DOWN FROM THE
UPPER GREAT LAKES. OVERALL EXPECT PLENTY OF DRY AIR AND SUBSIDENCE
THROUGHOUT THE MID LEVELS THROUGHOUT MOST OF WED AND INTO THURS.
AS FOR TEMPS...HEIGHTS WILL BE RISING THROUGH MID WEEK WITH A RISE
IN 850 TEMPS FROM 12C ON WED UP CLOSE TO 15C BY THURS. THE VERY DRY
AIR INITIALLY WILL CONTINUE TO PRODUCE LARGE DIURNAL SWINGS BUT THE
INCREASED MOISTURE IN THE LOW LEVELS BY THURS WILL BRING DEWPOINT
TEMPS UP ABOUT 10 DEGREES TO NEAR 65 CLOSER TO THE
COAST...ESPECIALLY NC COAST. THEREFORE EXPECT DAY TIME HIGHS
RISING A COUPLE OF DEGREES BETWEEN WED AND THURS...BETWEEN 80 AND
85 MOST PLACES. OVERNIGHT LOWS WILL INCREASE ALSO FROM CLOSER TO
60 WED IN MORE IDEAL RADIATIONAL COOLING CONDITIONS TO CLOSER TO
65 BY FRI MORNING.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...LARGE 5H RIDGE ACROSS THE EAST TRANSITIONS TO
MID-LEVEL SPLIT FLOW AS A NORTHERN STREAM LOW DRAGS A COLD FRONT
TOWARDS THE CAROLINAS ON SATURDAY. THIS FRONT TRIES TO PUNCH INTO A
VERY DRY AIR MASS...AND IS ACCOMPANIED ONLY BY WEAK (AND WEAKENING)
MID-LEVEL FORCING. WITH PWATS STILL ONLY AROUND ONE-INCH...AND MEX
P24 VALUES STILL WELL BELOW CLIMO...EXPECT THE WKND TO BE MOSTLY
DRY. HOWEVER...CANNOT RULE OUT SOME ISOLATED SHOWERS EITHER SAT OR
SUN AND THUS WILL KEEP INHERITED SCHC POP.
A MORE ROBUST MID-LEVEL SYSTEM ROTATES NORTHEAST FROM THE GULF COAST
REGION FOR THE BEGINNING OF THE WEEK...AND IS ACCOMPANIED BY AN
INCREASING SURFACE REFLECTION AND WARM FRONT. ALTHOUGH IT APPEARS
BEST FORCING REMAINS WEST OF THE IMMEDIATE CWA...LIFT ALONG THE WARM
FRONT IN A MOISTENING AIR MASS WILL PROVIDE INCREASING SHOWER
POTENTIAL MONDAY INTO TUESDAY AND WILL CARRY LOW-CHC FOR NOW...BUT
THIS WILL BE THE BEST CHANCE FOR RAIN THROUGH THE EXTENDED.
MAX TEMPS WILL BE SLIGHTLY ABOVE CLIMO FRI/SAT BEFORE FALLING BACK
TO NEAR SEASONABLE LEVELS FOR THE BEGINNING OF THE WEEK. MINS EACH
NIGHT WILL BE AROUND TO JUST ABOVE CLIMATOLOGICAL NORMS.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 06Z...EXPECT VFR TO PREVAIL THROUGH THE PERIOD...WITH
EXCEPTION OF POSSIBLE MVFR AT KLBT BEFORE DAYBREAK DUE TO FOG.
OVERNIGHT...GENERALLY LIGHT NORTHEAST WINDS WILL CONTINUE. GIVEN
IDEAL RADIATIONAL COOLING OVERNIGHT...CANNOT RULE OUT MVFR FOG AT
KLBT JUST BEFORE DAYBREAK. GIVEN LOWERED CONFIDENCE HAVE OPTED TO
INTRODUCE TEMPO GROUP. AFTER DAYBREAK...VFR WILL PREVAIL WITH
NORTHEAST WINDS GRADUALLY INCREASING TO AOB 10 KTS. GIVEN FCST
SOUNDINGS AND GUIDANCE...CONTINUE TO ANTICIPATE FEW/SCT DIURNAL CU
TO DEVELOP ACROSS THE AREA IN THE AFTERNOON...AROUND 5-6KFT. SKIES
WILL CLEAR AND WINDS WILL BECOME LIGHT INTO THE OVERNIGHT HOURS.
THE EXTENDED OUTLOOK THROUGH SUNDAY...POTENTIAL FOR BRIEF REDUCED
VSBYS AT FOG PRONE TERMINALS KCRE/KLBT IN THE PRE-DAWN HOURS
THURSDAY THROUGH SUNDAY. OTHERWISE EXPECT VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 11:05 PM TUESDAY...ELONGATED CENTER OF HIGH PRESSURE EXTENDED
FROM THE MID-ATLANTIC STATES NE TO MARTHAS VINEYARD. THIS PRESSURE
PATTERN WILL YIELD A NE-E WIND DIRECTION. A SLIGHTLY PINNED SFC PG
ACROSS THE EASTERN CAROLINAS WILL PRODUCE 10-15 KT WIND SPEEDS.
DECAYING TROPICAL SWELL AND WIND DRIVEN WAVES TO COMBINE TO PRODUCE
2 TO 4 FT OVERALL SEAS.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
CANADIAN HIGH PRESSURE WILL SETTLE DOWN OVER THE SOUTHEAST WHILE
SHIFTING SLOWLY EAST. AS THE CENTER SLIPS OFF THE NEW ENGLAND
COAST...IT WILL CONTINUE TO RIDGE DOWN INTO THE CAROLINAS. THIS WILL
HELP VEER WINDS AROUND THROUGH THE PERIOD FROM N-NE EARLY WED TO NE
TO E BY THURS NIGHT. GRADIENT FLOW WILL WEAKEN WITH WINDS NE
AROUND 15 KTS AND UP TO 20 IN OUTER WATERS ON WED. BY LATE THURS
WINDS WILL BE DOWN TO 10 TO 15 KTS.
OVERALL SEAS WILL DIMINISH A BIT BUT THE ONSHORE PUSH WILL KEEP
SEAS IN THE 2 TO 4 FT RANGE. LONGER PERIOD SWELL WILL DROP OFF BY
WED EVENING.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...HIGH PRESSURE RIDGING DOWN THE COAST
THROUGH THE PERIOD CREATES PREDOMINANTLY E/NE WINDS ACROSS THE
WATERS. THE PRESSURE GRADIENT WILL EASE THROUGH THE WKND...SO THE
STRONGEST WINDS...10-15 KTS...WILL OCCUR EARLY FRIDAY...BEFORE
FALLING TO LESS THAN 10 KTS THROUGH THE REST OF THE PERIOD. BY
LATE SUNDAY...RETURN FLOW WILL ONCE AGAIN DEVELOP...TURNING WINDS
TO THE SW BUT REMAINING LESS THAN 10 KTS. SEAS WILL BE PRIMARILY
2-4 FT THANKS TO A NE WIND WAVE..BUT MAY BUILD SUNDAY AS SOME
INCREASING LONG PERIOD SWELL FROM A TROPICAL DISTURBANCE WORKS
INTO THE LOCAL WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DCH/8
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...SGL/8
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
339 AM CDT WED SEP 12 2012
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
339 AM CDT WED SEP 12 2012
MAIN FORECAST CONCERNS ARE PRECIPITATION AND TEMPERATURE TRENDS
THROUGH THURSDAY...THEN POTENTIAL FOR VALLEY FOG AND PATCHY FROST
THURSDAY NIGHT INTO FRIDAY MORNING.
AS OF 08Z WEDNESDAY...WATER VAPOR IMAGERY AND RAP 500MB HEIGHT
FIELDS DEPICT A LARGE TROUGH ACROSS SOUTHERN CANADA INTO THE
NORTHERN PLAINS WHILE A LARGE RIDGE OF HIGH PRESSURE WAS CENTERED
ACROSS THE SOUTHEAST US. IN-BETWEEN...A PLUME OF SOUTHWEST MONSOONAL
MOISTURE WAS BEING ADVECTED NORTHEAST TOWARDS THE FORECAST AREA
WHERE PRECIPITABLE WATER VALUES RANGED FROM 0.75 TO 1.1 INCHES / 80
TO 120 PERCENT OF NORMAL / PER GOES SOUNDER IMAGERY. A 250MB JET
STREAK WAS NOTED ACROSS NORTHERN NORTH DAKOTA INTO EXTREME SOUTHWEST
ONTARIO. AT THE SURFACE...A COLD FRONT STRETCHED FROM NORTHWEST
WISCONSIN TO THE TWIN CITIES TO OMAHA NEBRASKA WHERE COMBINED WITH
INCREASING 850 MB TRANSPORT AHEAD OF THE FRONT AND MID TO UPPER
LEVEL FRONTOGENETICAL SUPPORT WAS GENERATING POST FRONTAL SHOWERS.
MEANWHILE...SOME WARM AIR ADVECTION SHOWERS AHEAD AND ALONG THE
FRONT WERE DEVELOPING ACROSS NORTHERN IOWA INTO SOUTHERN MINNESOTA.
DEWPOINT DEPRESSIONS REMAINED 25 TO 30F BUT A FEW SITES WERE
REPORTING PRECIPITATION UNDER 8 TO 10 KFT CLOUD BASES. LATEST IR
IMAGERY SHOWS HIGH CLOUDS ACROSS MUCH OF THE FORECAST AREA.
TODAY AND TONIGHT...EXCELLENT AGREEMENT BETWEEN THE LATEST
NAM/GFS/ECMWF/SREF/RAP DEPICTING THE COLD FRONT MAKING A STEADY
PROGRESS SOUTHEAST THROUGH THE FORECAST AREA SUCH THAT BY 12Z IT
SHOULD BE ALONG A BLACK RIVER FALLS TO LA CROSSE WISCONSIN TO
CHARLES CITY IOWA LINE. TEMPERATURES ARE TRICKY WITH CONTINUED
SOUTHWEST FLOW EXPECTED AHEAD OF THE FRONT WHERE LOCATIONS IN
NORTHEAST IOWA AND EXTREME SOUTHWEST WISCONSIN SHOULD REMAIN IN WARM
SECTOR FOR MUCH OF THE DAY...TOPPING OUT IN THE LOWER TO MIDDLE
80S. NON-DIURNAL TREND ON TRACK FOR OTHER SPOTS WHERE HIGHS SHOULD
OCCUR AROUND 18Z...FALLING INTO THE MIDDLE 60S BY 21Z. AS DEWPOINTS
CRASH INTO THE UPPER 40S LATE THIS AFTERNOON AND PRECIPITATION
BEGINS...TEMPERATURES LOOK TO QUICKLY DROP OFF.
DYNAMICS LOOK GOOD WITH FORECAST AREA FAVORABLY POSITIONED IN THE
RIGHT ENTRANCE REGION OF THE 250MB JET. A NW-SE CROSS SECTION
THROUGH THE REGION SHOWS STRONG FRONTOGENETICAL BAND WITH IDEAL
FRONTOLYSIS/FRONTOGENETICAL CIRCULATION SETTING UP ACROSS THE AREA
BEGINNING THIS EVENING. STRONG ISENTROPIC UPGLIDE ON THE 305-315K
SURFACES IS PRESENT ALONG WITH DECENT 850 MB MOISTURE TRANSPORT.
DESPITE SOME LOW LEVEL DRY AIR CONCERNS INITIALLY...THAT SHOULD BE
OVERCOME SUCH THAT SHOWERS WILL DEVELOP / MOVE INTO SOUTHEAST
MINNESOTA AND WESTERN WISCONSIN BETWEEN 22-00Z...THEN SAG SOUTHEAST
THROUGH THE NIGHT. THE LATEST MESO MODELS ARE IN GOOD AGREEMENT WITH
THIS SCENARIO AS WELL. REGARDING RAINFALL TOTALS THROUGH THE
EVENT...A NORTH/SOUTH GRADIENT SHOULD SET UP AS BETTER FORCING/LIFT
ACROSS IOWA INTO SOUTHERN WISCONSIN. TOTALS AROUND 1/10 OF AN INCH
ACROSS NORTH CENTRAL WISCONSIN....TO 1/3 TO 1/2 ALONG THE I-90
CORRIDOR...THE UPWARDS OF 3/4 OF AN INCH LOOK PROMISING FOR THE
AREA.
THURSDAY AND FRIDAY...BY 12Z THURSDAY...THE BULK OF THE
PRECIPITATION SHOULD BE ORIENTED THROUGH CENTRAL WISCONSIN TO
NORTHEAST IOWA. TIMING THE PROGRESS OF THIS PRECIPITATION OUT OF THE
FORECAST AREA IS A BIT TRICKY. THIS IS MOST LIKELY DUE TO MODEL
TIMING DIFFERENCES INCREASING ON HOW THE NEXT SHORTWAVE...CURRENTLY
IN NORTHWEST ALBERTA...DIVING SOUTHEAST DURING THE DAY THURSDAY IS
HANDLED. THE 12.00Z NAM IS A SLOWER OUTLIER...WHILE THE 12.00Z
GFS/CANADIAN/ECMWF ARE IN GOOD AGREEMENT. HAVE DISCOUNTED THE NAM
FOR THE TIME BEING...GIVEN TRENDS OVER THE PAST DAY TO BE FASTER.
THE HIGHEST PRECIPITATION CHANCES AFTER 15Z THURSDAY LOOK TO BE
SOUTH/EAST OF A SPARTA WISCONSIN TO OELWEIN IOWA LINE. A COOL DAY ON
TAP FOR THE AREA WITH MOSTLY CLOUDY TO CLOUDY SKIES UNDER COLD AIR
ADVECTION AND 850MB TEMPS PROGGED TO BE 5-8C. AREAS SOUTH/EAST WILL
BE THE COOLEST WITH MORE CLOUDS/RAIN...AND PROBABLY WILL ONLY MAKE
IT TO 60F AT BEST. AS THE NORTHWEST ALBERTA SHORTWAVE DIVES THROUGH
MINNESOTA DURING THE AFTERNOON AND COMBINES WITH DIURNAL
HEATING...SCATTERED SHOWERS ARE POSSIBLE...MAINLY CONFINED TO THE
NORTHWEST AREAS. STEEPER LAPSE RATES AND MAYBE SOME INSTABILITY TO
WORK WITH COULD PRODUCE A RUMBLE OR TWO OF THUNDER AS WELL.
THE NORTHWEST ALBERTA SHORTWAVE QUICKLY PIVOTS THROUGH THE NORTHERN
PLAINS LATE THURSDAY AND BY 06Z FRIDAY SHOULD BE CENTERED ACROSS
WISCONSIN. AT THE SURFACE...BUILDING CANADIAN HIGH PRESSURE THURSDAY
NIGHT INTO FRIDAY MORNING WILL BRING SOME OF THE COLDEST AIR OF THE
AUTUMN SEASON THUS FAR. THE COMBINATION OF PRECIPITABLE WATER VALUES
DROPPING TO A 0.5 INCH OR LESS...DIMINISHING WINDS WITH THE HIGH
PRESSURE AREA BUILDING IN AND CLEARING SKIES WILL ALL HELP
TEMPERATURES TO TANK. LOWS LOOK TO DROP DOWN TO THE LOWER 40S TO
AROUND 40 FOR MOST LOCATIONS. ALONG AND NORTHEAST OF THE I-94
CORRIDOR IN WISCONSIN...THE TYPICAL COLD SPOTS COULD EVEN SEE SOME
PATCHY FROST...THOUGH THIS WOULD ALL HINGE ON THE SURFACE HIGH
POSITION. RIVER VALLEY FOG WOULD ALSO BE A CONCERN GIVEN THIS
SYNOPTIC SETUP...ESPECIALLY GIVEN EXPECTED RAINFALL OVER THE NEXT 36
HOURS AND THE COOLER AND CLOUDIER DAY EXPECTED THURSDAY. RIGHT NOW
THE GFS IS A FASTER OUTLIER IN BRINGING IN THE SURFACE HIGH...MAKING
ITS SOLUTION THE MOST FAVORABLE FOR WIDESPREAD VALLEY FOG AND ALSO
MORNING FROST ACROSS NORTH CENTRAL WISCONSIN. DEFINITELY SOMETHING
TO WATCH CLOSELY IN THE NEXT FORECAST RUNS. FOR NOW HAVE ONLY
INCLUDED AREAS OF FOG FOR THE WISCONSIN RIVER AND ITS TRIBUTARIES...
AND PATCHY FOG FOR THE MISSISSIPPI RIVER. FRIDAY LOOKS TO BE A VERY
PLEASANT DAY FOR THE ENTIRE UPPER MIDWEST WITH THE HIGH PRESSURE
DRIFTING OVERHEAD...PROVIDING LIGHT WINDS. 850MB TEMPS OF 6-8C AND
PLENTY OF SUN SHOULD RESULT IN HIGHS SLIGHTLY BELOW NORMAL...IN THE
UPPER 60S TO LOWER 70S.
QUIET WEATHER LOOKS TO PERSIST INTO FRIDAY NIGHT WITH THE HIGH
PRESSURE REMAINING NEARBY. LOW PRECIPITABLE WATER VALUES ARE STILL
SUGGESTED...SO ANOTHER COOL NIGHT IS EXPECTED WITH LOWS IN THE UPPER
30S AT THE TYPICAL COLD SPOTS AND LOW TO MID 40S ELSEWHERE. MAY
AGAIN BE DEALING WITH VALLEY FOG AND FROST.
.LONG TERM...SATURDAY THROUGH TUESDAY NIGHT
339 AM CDT WED SEP 12 2012
12.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES ARE IN MUCH BETTER
AGREEMENT ON THE UPPER LEVEL PATTERN COMPARED TO THE PAST FEW DAYS
FOR THE LONG TERM FORECAST. THERE STILL ARE SOME ISSUES...MOSTLY
IMPACTING TUESDAY AND TUESDAY NIGHT.
TO BEGIN THE LONG TERM FORECAST...NEARLY ZONAL FLOW EXISTS WITH THE
WESTERLIES RUNNING ACROSS SOUTHERN CANADA. WITHIN THIS FLOW...
THOUGH...THERE IS A POTENT SHORTWAVE CROSSING NORTHERN SASKATCHEWAN
WITH INDICATIONS OF TROUGHING BEGINNING TO FORM OVER WESTERN
ALBERTA. THIS TROUGHING ENDS UP DEEPENING ACROSS CENTRAL CANADA BY
LATE SUNDAY DUE TO RIDGING BUILDING UP INTO BRITISH COLUMBIA. AHEAD
OF THIS UPPER TROUGHING AND ASSOCIATED WITH THAT POTENT SHORTWAVE...
MODELS DEPICT A COLD FRONT. THIS FRONT LOOKS TO CROSS THE FORECAST
AREA SUNDAY NIGHT AT THE PRESENT TIME...WHICH IS WHEN THE TROUGHING
BEGINS TO DIG DOWN INTO THE NORTH CENTRAL U.S.. ANTICIPATING DRY
WEATHER UNTIL THIS FRONT PASSES...DUE TO THE DRY AIRMASS AHEAD OF
IT. WITH 850MB TEMPS RUNNING AROUND 8C ON SATURDAY AND 10-12C ON
SUNDAY...HIGH TEMPERATURES BOTH DAYS SHOULD BE ABLE TO TOP OUT IN
THE 70S. CHANGES ARE DEFINITELY ON THE WAY FOR MONDAY...THOUGH...AS
THE UPPER TROUGH APPROACHES THE AREA. LIKE TODAY THROUGH THURSDAY...
INDICATIONS ARE THAT A FRONTOGENETIC BAND OF PRECIPITATION WILL FORM
BEHIND THE COLD FRONT. HOW MUCH PRECIPITATION FORMS DEPENDS ON HOW
MUCH THE UPPER TROUGHING DIGS DOWN INTO THE NORTH CENTRAL U.S....
WHICH IS A LITTLE UNCERTAIN AT THIS TIME. THEREFORE...WILL BE
FOLLOWING THE CONSENSUS PRECIPITATION CHANCES OF 30-40 FOR MONDAY
AND MONDAY NIGHT. IF MODEL TRENDS CONTINUE...CHANCES ARE LIKELY
GOING TO BE RAISED IN LATER FORECASTS FOR MONDAY AND MONDAY NIGHT.
THE FORECAST FOR TUESDAY AND TUESDAY NIGHT ALSO RELY ON WHAT HAPPENS
WITH THE NORTH CENTRAL U.S. TROUGH. THE 12.00Z GFS FORMS A CLOSED
UPPER LOW OVER THE FORECAST AREA WHILE THE 11.12Z/12.00Z ECMWF KEEP
THE TROUGH PROGRESSIVE. THE FORMER SCENARIO YIELDS WET WHILE THE
LATTER SCENARIO SUGGESTS DRY...THOUGH BOTH ARE COOL AS 850MB TEMPS
TUMBLE TO A CHILLY 0-2C. 12.00Z GFS ENSEMBLES SUGGESTS BOTH THE GFS
AND ECMWF ARE POSSIBLE...THEREFORE 20-30 PERCENT CHANCES OF
PRECIPITATION ARE IN THE FORECAST. HIGHS TUESDAY WILL BE AT LEAST 15
DEGREES COLDER THAN THOSE ON SUNDAY...IF NOT MORE.
&&
.AVIATION...THROUGH 06Z THURSDAY
1149 PM CDT TUE SEP 11 2012
A COLD FRONT EXTENDED FROM NORTHWEST WISCONSIN INTO NORTHWEST IOWA
LATE THIS EVENING. THIS FRONT IS EXPECTED TO MOVE THROUGH THE TAF
SITES BETWEEN 12 AND 15Z WEDNESDAY BRINGING THE WINDS AROUND TO
THE NORTHWEST AND THEN NORTH. REGIONAL RADARS SHOWING SOME SHOWERS
ALONG AND BEHIND THE FRONT WITH SOME RAIN HITTING THE GROUND OVER
WESTERN MINNESOTA INTO SOUTH DAKOTA. THIS IS OCCURRING IN A ZONE
OF 1000-850 MB FRONTOGENESIS WHICH WILL MOVE INTO THE AREA BEHIND
THE FRONT. BOTH THE 12.12Z HI-RES ARW AND NMM BROUGHT SOME SHOWERS
INTO THE KRST AREA WEDNESDAY MORNING IN THIS ZONE OF FRONTOGENESIS...
SO HAVE CONTINUED THE INCLUSION OF SOME VCSH. BOTH MODELS SHOW
THESE WEAKENING AS THEY WORK DEEPER INTO THE DRY AIR SO FOR NOW
HAVE NOT INCLUDED AT KLSE. THE FORCING BECOMES STRONGER DURING THE
LATE AFTERNOON AND EVENING AS THE FRONTOGENESIS BECOME MODERATE IN
STRENGTH DEEPENS UP TO 500 MB. SOME LIFT WILL ALSO BE PROVIDED
FROM AN APPROACHING SHORT WAVE TROUGH AND WITH UP TO 6 UBAR/S OF
UP GLIDE ON THE 305K ISENTROPIC SURFACE. HAVE INCLUDED CATEGORICAL
SHOWERS FOR BOTH SITES WITHOUT ANY VISIBILITY RESTRICTIONS AT THIS
POINT. THE FORCING LOOKS TO TRANSITION EAST FAIRLY QUICK THAT THE
SHOWERS SHOULD END BEFORE 06Z THURSDAY IN KRST AND SHORTLY AFTER
AT KLSE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
339 AM CDT WED SEP 12 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...AJ
AVIATION...04
AREA FORECAST DISCUSSION
NWS MIAMI FL
1013 AM EDT WED SEP 12 2012
.UPDATE...
THE 12Z SOUNDING THIS MORNING SHOWED DRIER AND WARMER AIR IN THE
LOW TO MID LEVELS...WITH MODERATE EAST TO NORTHEAST FLOW UP TO
700MB. THERE WAS A WEAK BOUNDARY LOCATED ACROSS THE FLORIDA
STRAITS...AND THE HIGHER MOISTURE AND CONVERGENCE WILL BE LOCATED
SOUTH OF THE REGION TODAY. THE HRRR SHOWS THIS AS WELL...WITH
MOSTLY ISOLATED TO SCATTERED SHOWERS AS THERE WILL BE A LACK OF
FOCUS FOR STORMS. A NORTHEAST FLOW USUALLY DOES NOT FAVOR MUCH
ACTIVITY ALONG MOST OF THE EAST COAST ANYWAY...BUT WILL LEAVE THE
HIGHER POPS FOR THE SOUTHEAST COAST AS THAT REGION IS CLOSER TO
THE BOUNDARY. LOWERED POPS ACROSS THE WEST BACK TO SCATTERED AND
REDUCED TO ISOLATED THUNDERSTORMS ACROSS THE WEST AS WELL...AS THE
FLOW SHOULD BE TOO STRONG TO GET A GULF COAST SEA BREEZE.
OTHERWISE...BREEZY CONDITIONS WITH PARTLY CLOUDY TO MOSTLY CLOUDY
SKIES SHOULD PREVAIL ACROSS THE REGION...WITH HIGHS IN THE UPPER
80S TO LOWER 90S.
&&
.PREV DISCUSSION... /ISSUED 726 AM EDT WED SEP 12 2012/
AVIATION...
A STALLED FRONT OVER EXTREME S FLA/THE UPPER FLA STRAITS
WILL DISSIPATE TODAY. A STRONG RIDGE OF HIGH PRESSURE OFF OF THE NEW
ENGLAND COAST OVER THE ATLC AND EXTENDING SW INTO THE SE U.S. WILL
PERSIST THROUGH THE PERIOD. A FEW FAST MOVING SHRA MOVING OVER THE
ATLC WILL MOVE ONSHORE BUT AT THIS TIME NO VCSH IN E COAST TAFS. AFT
16Z VCTS E COAST TERMINALS BUT POSSIBLE THAT THE TSRA WILL BE W OF
TERMINALS. SURFACE WINDS CURRENTLY NE-ENE UP TO 10 KNOTS WITH GUSTS
TO MID/UPPER TEENS POSSIBLE. AFT 14Z WINDS INCREASE TO 12 TO 15
KNOTS WITH GUSTS > 20 KNOTS. AT KAPF...VFR THROUGH 16Z WITH NO
WEATHER THEN VCSH POSSIBLE UNTIL 18Z THEN VCTS. TSTMS MAY PRODUCE
FREQUENT MVFR CIG/VSBY. SURFACE WIND CURRENTLY NE < 10 KNOTS
BECOMING NE-ENE 10 TO 12 KNOTS WITH GUSTS AROUND 20 KNOTS AFT 15Z.
60
PREV DISCUSSION... /ISSUED 307 AM EDT WED SEP 12 2012/
SHORT TERM (TODAY-FRIDAY)...
A STALLED FRONTAL BOUNDARY COMBINED WITH PLENTY OF DEEP LAYER
MOISTURE WILL KEEP THE RAIN CHANCES IN THE FORECAST THROUGH THE
MID-WEEK PERIOD. EARLIER THIS MORNING...SCATTERED MODERATE TO
HEAVY SHOWERS DUE TO AN EASTERLY WIND SURGE NORTH OF THE FRONTAL
BOUNDARY IMPACTED PORTIONS OF THE LOCAL AREA...ESPECIALLY ALONG
THE EAST COAST FROM DELRAY BEACH TO LAKE WORTH WHERE ACCUMULATIONS
REACHED THE THREE QUARTER TO ONE INCH MARK WITHIN A ONE TO THREE
HOUR PERIOD. THE LATEST MODEL GUIDANCE REMAINS IN DECENT AGREEMENT
THROUGH THE UPCOMING 72 HOURS AND CONTINUES TO INDICATE THE
POTENTIAL FOR SCATTERED SHOWERS WITHIN THE MOIST EASTERLY FLOW TO
CONTINUE. MODEL PRECIPITABLE WATER VALUES ARE FORECAST TO REMAIN
AROUND THE 2 INCH MARK THROUGH THURSDAY...THEN STEADILY DECREASE
FROM NORTH TO SOUTH THURSDAY NIGHT THROUGH FRIDAY AS THE FRONTAL
BOUNDARY GRADUALLY SHIFTS SOUTH OF THE AREA AND FURTHER WEAKENS OR
DIMINISHES. AS A RESULT...WILL REFLECT THIS DECREASING RAINFALL
TREND THROUGH THE LATTER HALF OF THE SHORT-TERM PERIOD. FOR
TODAY...ALTHOUGH THE MODERATE EASTERLY FLOW WILL HELP SPREAD THE
AFTERNOON SHOWERS/TSTMS INLAND AND TOWARD THE SOUTHWEST FLORIDA
COAST...ANY ACTIVITY THAT BECOMES CONCENTRATED OVER PORTIONS OF
THE EAST COAST AND METRO AREAS ON TOP OF YESTERDAY`S RAINFALL
COULD LEAD TO MINOR FLOODING CONCERNS ONCE AGAIN.
LONG TERM (FRIDAY NIGHT-TUESDAY)...
OVER THE WEEKEND...THE MODERATE EASTERLY FLOW CURRENTLY IN PLACE
IS FORECAST TO RELAX AS THE FRONTAL BOUNDARY PREVIOUSLY DISCUSSED
DIMINISHES SOUTH OF THE AREA. THIS WILL ALLOW CONDITIONS TO RETURN
TO NORMAL FOR THIS TIME OF YEAR WITH MAINLY AFTERNOON
SHOWERS/TSTMS SETTING UP INLAND AND WEST EACH DAY. EARLY NEXT
WEEK...THE LATEST MODEL GUIDANCE INDICATES ANOTHER FRONTAL
BOUNDARY ASSOCIATED WITH A STRONG SHORTWAVE TROUGH TRANSLATING
EASTWARD ACROSS THE REGION. ALTHOUGH THE BULK OF THE DYNAMICS AND
FORCING WILL REMAIN WELL NORTH OF OUR LOCAL AREA...MOIST SOUTHERLY
FLOW WELL AHEAD OF THIS APPROACHING BOUNDARY MAY LEAD TO ABOVE
AVERAGE RAINFALL CHANCES MONDAY THROUGH TUESDAY...ESPECIALLY OVER
THE NORTHERN HALF OF THE LOCAL AREA AROUND THE LAKE REGION.
MARINE...
MODERATE EASTERLY WINDS AND SEAS WILL PERSIST THROUGH THE
MID-WEEK PERIOD...THEN STEADILY TREND BACK TOWARD NORMAL OVER THE
WEEKEND. AS A RESULT...SMALL CRAFT OPERATORS ARE ENCOURAGED TO
EXERCISE CAUTION OUT ACROSS THE LOCAL WATERS TODAY THROUGH THURSDAY.
IN ADDITION TO THE ABOVE AVERAGE WINDS AND SEAS...SCATTERED SHOWERS
AND STORMS CAN LEAD TO LOCALLY HIGHER WINDS AND SEAS ALONG WITH
REDUCED VISIBILITIES.
FIRE WEATHER...
A STALLED FRONT OVER EXTREME SOUTH FLORIDA AND THE UPPER FLORIDA
STRAITS WILL DISSIPATE TODAY. A STRONG RIDGE OF HIGH PRESSURE
.EXTENDING FROM THE ATLANTIC OFF OF THE NEW ENGLAND COAST
SOUTHWEST TO OVER THE SOUTHEAST U.S....WILL PERSIST TODAY THROUGH
THURSDAY. THIS WILL PROVIDE A BRISK NORTHEASTERLY WIND FLOW OVER
SOUTH FLORIDA TODAY THROUGH THURSDAY.
SOME SHOWERS CAN BE EXPECTED THIS MORNING ALONG THE EAST COAST AND
AGAIN OVERNIGHT TONIGHT. BUT BY LATE MORNING TODAY AND AGAIN ON
THURSDAY...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED MAINLY IN THE INTERIOR AND WEST ZONES.
DISPERSION WILL BE GENERALLY GOOD MOST ZONES TODAY AND THURSDAY WITH
VERY GOOD DISPERSION TODAY WEST OF LAKE OKEECHOBEE.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 88 78 88 77 / 40 30 40 20
FORT LAUDERDALE 88 79 89 79 / 50 30 30 20
MIAMI 87 78 89 78 / 50 30 40 20
NAPLES 92 75 91 76 / 50 40 50 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS GOODLAND KS
548 AM MDT WED SEP 12 2012
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 403 AM MDT WED SEP 12 2012
FORECAST PROBLEMS WILL BE PRECIPITATION TIMING/COVERAGE INTO
TOMORROW...HOW COOL TO MAKE HIGH TEMPERATURES THROUGH THURSDAY...
AND HOW COOL TO MAKE THE MINS THE NEXT THREE NIGHTS. SATELLITE
CONTINUING TO SHOW AN AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO
THE ATLANTIC. COMPLEX AND MODERATELY STRONG SHORTWAVE TROUGH MOVING
TOWARD THE AREA FROM THE SOUTHWEST. MID LEVEL MOISTURE HAS
INCREASED SIGNIFICANTLY FROM YESTERDAY WITH LOW LEVEL MOISTURE NOT
VERY PLENTIFUL. COLD FRONT IS CURRENTLY PLOWING THROUGH THE AREA.
AT JET LEVEL...THE NAM/CANADIAN WERE DOING SLIGHTLY BETTER THAN THE
ECMWF AND UKMET. THE GFS WAS A LITTLE TOO FAR EAST WITH THE UPPER
JET THAT WILL BE A MAIN PLAYER IN THE LIFT. AT MID LEVELS...MODELS
WERE HAVING TROUBLE CATCHING THE IMPORTANT DETAILS AND OVERALL
POSITION/STRENGTH OF THE INCOMING TROUGH. IN GENERAL THEY WERE TOO
DEEP AND/OR TOO FAST WITH THE TROUGH OVER THE SOUTHWEST PORTION OF
THE COUNTRY WITH THE NAM THE WORST OFFENDER. SATELLITE AND UPPER AIR
ANALYSIS WOULD SAY THE UKMET IS THE BEST RIGHT NOW. RUC WAS DOING
BEST WITH THE SHORT TERM FRONTAL POSITION AND WINDS FOLLOWED BY THE
NAM/CANADIAN. THE MODELS TENDED TO BE A LITTLE SLOW WITH THE FRONT.
THE GFS AND CANADIAN SEEM TO HAVE A DECENT HANDLE ON THE LOW LEVEL
THERMAL FIELD.
TODAY/TONIGHT...JET LIFT IS SLOWER TO ARRIVE THAN WHAT WAS SHOWN
YESTERDAY. BY 00Z IT LOOKS LIKE IT IS CLOSE TO OR OVER THE
NORTHWEST CORNER OF THE FORECAST AREA. THE JET LIFT REALLY DOES NOT
GET STRONG UNTIL BETWEEN 00Z TO 06Z IN THE NORTHWEST HALF GOING BY
THE SLIGHTLY FASTER SOLUTIONS. IT IS POSSIBLE THAT IT COULD BE
SLIGHTLY LATER. MOST OF THE MODELS ARE STILL SHOWING GOOD JET
SUPPORT/LIFT OVER THE CENTRAL AND SOUTHEAST PORTION OF THE AREA
BETWEEN 06Z AND 12Z. ALSO SYNOPTIC SCALE AND MESOSCALE FORCING
DOES NOT ARRIVE UNTIL LATER IN THE AFTERNOON.
MID LEVEL MOISTURE IS INCREASING ACROSS THE AREA. HOWEVER...LOW
LEVELS REMAIN INITIALLY DRY. SEEING RAINFALL INCREASE IN COVERAGE
AND INTENSITY ALONG THE FRONT RANGE OF COLORADO AT THIS TIME. SINCE
DEEPER MOISTURE AND LIFT IS SLOWER TO ARRIVE...SLOWED THE ARRIVAL
OF THE RAINFALL AND HIGHER POPS UNTIL LATER THIS AFTERNOON. ALL
MODELS MATCH UP WELL WITH THEIR SYNOPTIC SCALE/MESOSCALE FORCING...
QPF FIELDS...LOCAL POP PROGRAM OUTPUT...AND GEFS/SREF PROBABILITY FOR
MEASURABLE FIELDS SO HAVE HIGHER CONFIDENCE THAT MOST OF THE AREA
WILL RECEIVE MEASURABLE RAINFALL. IT WILL BY NO MEANS BE A SOAKER BUT
MEASURABLE LOOKS PRETTY GOOD.
THE HIGHEST CHANCE/COVERAGE OF PRECIPITATION WILL BE TONIGHT FIRST IN
THE NORTHWEST HALF THEN TRANSITION TO THE SOUTHEAST HALF AFTER 06Z.
TOOK THE MENTION OF THUNDERSTORMS OUT SINCE NOTHING INDICATES ANY
INSTABILITY AT THIS TIME. WHAT IS INTERESTING IS THIS IS
SUBTROPICAL MOISTURE AND PWS COME UP TO 1 TO 1.5 INCHES. EVEN THOUGH
NOT CONVECTIVE IN NATURE...THETA-E LAPSE RATES WOULD INDICATE A
GOOD RESPONSE TO THE LIFT.
CLOUD COVER IS THICKENING ALREADY WITH COLD AIR ADVECTION CONTINUING
THROUGH THE DAY FOLLOWED BY PRECIPITATION INCREASING THIS AFTERNOON.
SO KEPT THE COOL MAXES FOR THE DAY WITH GUIDANCE IN REASONABLE
AGREEMENT. WILL WATCH TRENDS FOR THE REST OF THE SHIFT AND MAY MAKE
FURTHER ADJUSTMENTS BASE ON HOW CURRENT TEMPERATURES ARE DOING.
DEPENDING ON HOW FAST IT CLEARS OUT TONIGHT...IT COULD GET A LITTLE
COOL. LOOKS LIKE THE NORTHERN PORTION WILL AND MADE MINS UP THERE
COOLER.
THURSDAY...PER ANALYSIS AND CURRENT TRENDS...IT IS POSSIBLE THAT THE
MODELS COULD BE TOO FAST IN BRINGING IN AND GETTING RID OF THE
PRECIPITATION. THERE LOOKS TO STILL BE SOME JET LIFT OCCURRING IN THE
SOUTHEAST PORTION THIRD OF THE AREA BETWEEN 12Z AND 18Z. IT WILL BE
CLOSE BUT THERE STILL BE SOME LINGERING JET LIFT NEAR 00Z. SO
SLOWLY DECREASED THE PRECIPITATION THROUGH THE DAY...ENDING BY 00Z.
DEPENDING ON HOW FAST THE CLEARING OCCURS WILL AFFECT THE MAXES. AT
THIS TIME IT LOOKS LIKE THE NORTH WILL BE THE WARMEST. TENDED TO
COMPROMISED BETWEEN THE WARMEST/COOLEST GUIDANCE ACCOUNTING FOR
THE POSSIBILITY OF SLOWER CLEARING.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 403 AM MDT WED SEP 12 2012
THURSDAY NIGHT...LOOKS LIKE THE AREA WILL CLEAR OUT BY 06Z. LOW
DEWPOINTS SINCE UPSTREAM. POSSIBLE THAT DEWPOINTS COULD BE LOWER
THAN WHAT I HAVE IN THERE. WIND FIELD GOES LIGHT AS WELL. KEPT THE
COOL MINS AND POSSIBLE THEY MAY NEED TO BE LOWERED. IF THEY ARE
LOWERED ANY MORE...SOME LOW LYING AREAS MAY SEE PATCHY FROST. NOT
READY TO GO THERE YET THOUGH.
FRIDAY/FRIDAY NIGHT...RIDGE BUILDS IN WITH PLENTY OF SUN. HOWEVER
MODELS CUT OFF A LOW ON THE WESTERN END OF THE TROUGH THAT HAS
MOVED THROUGH. THIS WILL KEEP AN EASTERLY FLOW ALOFT OVER THE AREA.
PLUS IF CIRCULATION ENDS UP BEING FURTHER NORTH...MORE CLOUDS AND
COOLER TEMPERATURES COULD BE IN STORE. AT THIS TIME HAVE THE
WARMEST IN THE NORTH AND COOLEST IN THE SOUTH WITH A TREND OF
COMPROMISING BETWEEN THE WARMER AND COOLER GUIDANCE. INDICATIONS
ARE THAT WIND FIELD COULD BE LIGHT WITH LOW DEWPOINTS STILL IN
PLACE. COULD BE ANOTHER COOL NIGHT WITH MINS POSSIBLY LOWER THAN I
HAVE THEM.
SATURDAY THROUGH TUESDAY...FLOW ALOFT WILL BE NORTHWESTERLY THROUGH
MOST OF THE PERIOD...WITH A TROUGH DIGGING OVER THE REGION LATE IN
THE PERIOD. A COLD FRONT WILL MOVE THROUGH THE AREA ON
MONDAY...BRINGING WITH IT A CHANCE FOR SHOWERS AND THUNDERSTORMS.
STILL A LOT OF UNCERTAINTY REGARDING TEMPERATURES ON MONDAY...BUT
BETTER AGREEMENT THAN YESTERDAY WITH THE TIMING OF THE FRONT.
GUIDANCE IS TRENDING COOLER...SO HAVE ADJUSTED HIGHS DOWNWARD A FEW
DEGREES ACROSS MUCH OF THE REGION. TEMPERATURES DURING THE PERIOD
WILL BE WARMEST ON SUNDAY WITH HIGH TEMPERATURES NEAR NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 545 AM MDT WED SEP 12 2012
COMPLICATED SET OF TAFS. INCOMING SHORTWAVE TROUGH AND UPPER JET
WILL CAUSE CLOUDS DECKS TO LOWER AND PRECIPITATION TO GRADUALLY
SPREAD OVER THE AREA. GREATEST CHANCE FOR PRECIPITATION WILL BEGIN
LATE THIS AFTERNOON AND CONTINUE THROUGH THE EVENING HOURS. MVFR
TO OCCASIONAL IFR CEILINGS AND VISIBILITIES WILL OCCUR FROM LATE
THIS AFTERNOON THROUGH THE EVENING. AFTER PRECIPITATION ENDS...IFR
TO LIFR CEILING WILL OCCUR UNTIL TOWARD THE END OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DDT/BULLER
LONG TERM...BULLER/CJS
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
403 AM MDT WED SEP 12 2012
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 403 AM MDT WED SEP 12 2012
FORECAST PROBLEMS WILL BE PRECIPITATION TIMING/COVERAGE INTO
TOMORROW...HOW COOL TO MAKE HIGH TEMPERATURES THROUGH THURSDAY...
AND HOW COOL TO MAKE THE MINS THE NEXT THREE NIGHTS. SATELLITE
CONTINUING TO SHOW AN AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO
THE ATLANTIC. COMPLEX AND MODERATELY STRONG SHORTWAVE TROUGH MOVING
TOWARD THE AREA FROM THE SOUTHWEST. MID LEVEL MOISTURE HAS
INCREASED SIGNIFICANTLY FROM YESTERDAY WITH LOW LEVEL MOISTURE NOT
VERY PLENTIFUL. COLD FRONT IS CURRENTLY PLOWING THROUGH THE AREA.
AT JET LEVEL...THE NAM/CANADIAN WERE DOING SLIGHTLY BETTER THAN THE
ECMWF AND UKMET. THE GFS WAS A LITTLE TOO FAR EAST WITH THE UPPER
JET THAT WILL BE A MAIN PLAYER IN THE LIFT. AT MID LEVELS...MODELS
WERE HAVING TROUBLE CATCHING THE IMPORTANT DETAILS AND OVERALL
POSITION/STRENGTH OF THE INCOMING TROUGH. IN GENERAL THEY WERE TOO
DEEP AND/OR TOO FAST WITH THE TROUGH OVER THE SOUTHWEST PORTION OF
THE COUNTRY WITH THE NAM THE WORST OFFENDER. SATELLITE AND UPPER AIR
ANALYSIS WOULD SAY THE UKMET IS THE BEST RIGHT NOW. RUC WAS DOING
BEST WITH THE SHORT TERM FRONTAL POSITION AND WINDS FOLLOWED BY THE
NAM/CANADIAN. THE MODELS TENDED TO BE A LITTLE SLOW WITH THE FRONT.
THE GFS AND CANADIAN SEEM TO HAVE A DECENT HANDLE ON THE LOW LEVEL
THERMAL FIELD.
TODAY/TONIGHT...JET LIFT IS SLOWER TO ARRIVE THAN WHAT WAS SHOWN
YESTERDAY. BY 00Z IT LOOKS LIKE IT IS CLOSE TO OR OVER THE
NORTHWEST CORNER OF THE FORECAST AREA. THE JET LIFT REALLY DOES NOT
GET STRONG UNTIL BETWEEN 00Z TO 06Z IN THE NORTHWEST HALF GOING BY
THE SLIGHTLY FASTER SOLUTIONS. IT IS POSSIBLE THAT IT COULD BE
SLIGHTLY LATER. MOST OF THE MODELS ARE STILL SHOWING GOOD JET
SUPPORT/LIFT OVER THE CENTRAL AND SOUTHEAST PORTION OF THE AREA
BETWEEN 06Z AND 12Z. ALSO SYNOPTIC SCALE AND MESOSCALE FORCING
DOES NOT ARRIVE UNTIL LATER IN THE AFTERNOON.
MID LEVEL MOISTURE IS INCREASING ACROSS THE AREA. HOWEVER...LOW
LEVELS REMAIN INITIALLY DRY. SEEING RAINFALL INCREASE IN COVERAGE
AND INTENSITY ALONG THE FRONT RANGE OF COLORADO AT THIS TIME. SINCE
DEEPER MOISTURE AND LIFT IS SLOWER TO ARRIVE...SLOWED THE ARRIVAL
OF THE RAINFALL AND HIGHER POPS UNTIL LATER THIS AFTERNOON. ALL
MODELS MATCH UP WELL WITH THEIR SYNOPTIC SCALE/MESOSCALE FORCING...
QPF FIELDS...LOCAL POP PROGRAM OUTPUT...AND GEFS/SREF PROBABILITY FOR
MEASURABLE FIELDS SO HAVE HIGHER CONFIDENCE THAT MOST OF THE AREA
WILL RECEIVE MEASURABLE RAINFALL. IT WILL BY NO MEANS BE A SOAKER BUT
MEASURABLE LOOKS PRETTY GOOD.
THE HIGHEST CHANCE/COVERAGE OF PRECIPITATION WILL BE TONIGHT FIRST IN
THE NORTHWEST HALF THEN TRANSITION TO THE SOUTHEAST HALF AFTER 06Z.
TOOK THE MENTION OF THUNDERSTORMS OUT SINCE NOTHING INDICATES ANY
INSTABILITY AT THIS TIME. WHAT IS INTERESTING IS THIS IS
SUBTROPICAL MOISTURE AND PWS COME UP TO 1 TO 1.5 INCHES. EVEN THOUGH
NOT CONVECTIVE IN NATURE...THETA-E LAPSE RATES WOULD INDICATE A
GOOD RESPONSE TO THE LIFT.
CLOUD COVER IS THICKENING ALREADY WITH COLD AIR ADVECTION CONTINUING
THROUGH THE DAY FOLLOWED BY PRECIPITATION INCREASING THIS AFTERNOON.
SO KEPT THE COOL MAXES FOR THE DAY WITH GUIDANCE IN REASONABLE
AGREEMENT. WILL WATCH TRENDS FOR THE REST OF THE SHIFT AND MAY MAKE
FURTHER ADJUSTMENTS BASE ON HOW CURRENT TEMPERATURES ARE DOING.
DEPENDING ON HOW FAST IT CLEARS OUT TONIGHT...IT COULD GET A LITTLE
COOL. LOOKS LIKE THE NORTHERN PORTION WILL AND MADE MINS UP THERE
COOLER.
THURSDAY...PER ANALYSIS AND CURRENT TRENDS...IT IS POSSIBLE THAT THE
MODELS COULD BE TOO FAST IN BRINGING IN AND GETTING RID OF THE
PRECIPITATION. THERE LOOKS TO STILL BE SOME JET LIFT OCCURRING IN THE
SOUTHEAST PORTION THIRD OF THE AREA BETWEEN 12Z AND 18Z. IT WILL BE
CLOSE BUT THERE STILL BE SOME LINGERING JET LIFT NEAR 00Z. SO
SLOWLY DECREASED THE PRECIPITATION THROUGH THE DAY...ENDING BY 00Z.
DEPENDING ON HOW FAST THE CLEARING OCCURS WILL AFFECT THE MAXES. AT
THIS TIME IT LOOKS LIKE THE NORTH WILL BE THE WARMEST. TENDED TO
COMPROMISED BETWEEN THE WARMEST/COOLEST GUIDANCE ACCOUNTING FOR
THE POSSIBILITY OF SLOWER CLEARING.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 403 AM MDT WED SEP 12 2012
THURSDAY NIGHT...LOOKS LIKE THE AREA WILL CLEAR OUT BY 06Z. LOW
DEWPOINTS SINCE UPSTREAM. POSSIBLE THAT DEWPOINTS COULD BE LOWER
THAN WHAT I HAVE IN THERE. WIND FIELD GOES LIGHT AS WELL. KEPT THE
COOL MINS AND POSSIBLE THEY MAY NEED TO BE LOWERED. IF THEY ARE
LOWERED ANY MORE...SOME LOW LYING AREAS MAY SEE PATCHY FROST. NOT
READY TO GO THERE YET THOUGH.
FRIDAY/FRIDAY NIGHT...RIDGE BUILDS IN WITH PLENTY OF SUN. HOWEVER
MODELS CUT OFF A LOW ON THE WESTERN END OF THE TROUGH THAT HAS
MOVED THROUGH. THIS WILL KEEP AN EASTERLY FLOW ALOFT OVER THE AREA.
PLUS IF CIRCULATION ENDS UP BEING FURTHER NORTH...MORE CLOUDS AND
COOLER TEMPERATURES COULD BE IN STORE. AT THIS TIME HAVE THE
WARMEST IN THE NORTH AND COOLEST IN THE SOUTH WITH A TREND OF
COMPROMISING BETWEEN THE WARMER AND COOLER GUIDANCE. INDICATIONS
ARE THAT WIND FIELD COULD BE LIGHT WITH LOW DEWPOINTS STILL IN
PLACE. COULD BE ANOTHER COOL NIGHT WITH MINS POSSIBLY LOWER THAN I
HAVE THEM.
SATURDAY THROUGH TUESDAY...FLOW ALOFT WILL BE NORTHWESTERLY THROUGH
MOST OF THE PERIOD...WITH A TROUGH DIGGING OVER THE REGION LATE IN
THE PERIOD. A COLD FRONT WILL MOVE THROUGH THE AREA ON
MONDAY...BRINGING WITH IT A CHANCE FOR SHOWERS AND THUNDERSTORMS.
STILL A LOT OF UNCERTAINTY REGARDING TEMPERATURES ON MONDAY...BUT
BETTER AGREEMENT THAN YESTERDAY WITH THE TIMING OF THE FRONT.
GUIDANCE IS TRENDING COOLER...SO HAVE ADJUSTED HIGHS DOWNWARD A FEW
DEGREES ACROSS MUCH OF THE REGION. TEMPERATURES DURING THE PERIOD
WILL BE WARMEST ON SUNDAY WITH HIGH TEMPERATURES NEAR NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1105 PM MDT TUE SEP 11 2012
VFR CONDITIONS WILL PERSIST THROUGH 22Z OR SO FOR BOTH TERMINALS.
DURING THIS TIME PERIOD NORTH TO NORTHEAST WINDS OF 20-25KTS WITH
GUSTS TO 35 KTS EXPECTED. AFTER 22Z CIGS WILL START TO DECREASE AS
LOW LEVEL MOISTURE INCREASES FROM THE WEST. MVFR/IFR CIGS EXPECTED
BY 00Z CONTINUING THROUGH 06Z. RAIN SHOWERS EXPECTED AROUND 00Z
WITH A STEADY RAIN AND SOME FOG/BR EXPECTED IN THE 01Z-05Z TIME
FRAME BEFORE TRANSITIONING BACK TO A MORE SHOWERY TYPE AS THE
FORCING AND MOISTURE SLOWLY MOVE EAST OF BOTH TERMINALS. THE
STRONG AND GUSTY NORTH TO NORTHEAST WINDS SHOULD TAPER OFF
SIGNIFICANTLY BY 00Z OR SHORTLY THEREAFTER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DDT/BULLER
LONG TERM...BULLER/CJS
AVIATION...DDT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
649 AM CDT WED SEP 12 2012
.UPDATE...
12Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
QUITE A DIFFERENCE A DAY MAKES WITH EXPECTED TEMPERATURES TODAY AT
LEAST 20 DEGREES COOLER THAN YESTERDAY. CDFNT NOW PASSING ACROSS
THE METRO WITH TEMPS FALLING A GOOD 10 DEGREES IN AN HOUR OR TWO IN
WAKE OF FROPA. WITH BLANKET OF POST FRONTAL CLOUDS DON`T EXPECT MUCH
IN THE WAY OF TEMPERATURE RECOVERY TODAY. COOLING IN WAKE OF FRONT
IS ALSO BEING AIDED BY VERY LOW DEW POINT DEPRESSIONS YIELDING HIGH
EVAPORATIVE COOLING ACROSS AREAS WHICH HAVE RECEIVED LIGHT PRECIP
OVERNIGHT.
-RA AND EVEN SOME ISOL THUNDER REMAINS IN A SW-NE BAND ACROSS SODAK
THEN ACROSS CENTRAL MN IN PLUME OF ELEVATED MOISTURE. PRECIP
AMOUNTS HAVE GENERALLY BEEN A FEW HUNDREDTHS OF AN INCH...BUT ARND
.10 AT BENSON...APPLETON AND MADISON SO FAR. HRRR HAS BEEN DOING A
PRETTY GOOD JOB ON HANDLING THIS AREA OF PCPN WHICH HAS SOME SUPPORT
FROM RIGHT ENTRANCE REGION OF UPPER JET. INCREASED POPS FOR THE
MORNING ACROSS CENTRAL MN.
ANOTHER AREA OF SHWRS AND ISOL THUNDER HAS ALSO BEEN BEEN DEVELOPING
IN NW IA BACK INTO NEB. THIS AREA SHOULD CONTINUE TO DEVELOP DURING
THE DAY TODAY AS UPPER WAVE LIFTS OUT CO BACKING MID LEVEL WINDS AND
GENERATING FAVORABLE UPGLIDGE AROUND THE 305K SURFACE. INCREASED
POPS MAINLY ACRS S MN INTO THE KEAU AREA FOR LATER THIS MORNING AND
AFTN.
FOR THURSDAY A SHARP AND FAST MOVING UPPER TROF DIVES OUT OF THE
PRAIRIE PROVINCES OF CANADA TO NEAR NW CORNER MN BY 12Z AND INTO WI
BY 00Z THURSDAY. NOT MUCH MOISTURE AVAILABLE FOR PCPN...BUT
CONSIDERING PATH OF THIS FEATURE ACROSS AREA DURING THE DAYLIGHT AND
B24 500MB TEMPS...IT IS WORTHY OF A MENTION OF SLIGHT CHC POPS AND
ISOL THUNDER.
MODERATING TEMPERATURES OVER THE WEEKEND AS SOUTHERLY FLOW DEVELOPS
AHEAD OF NEXT IMPRESSIVE LOOKING COLD FRONT. FRONT COMES ACROSS
AREA SUNDAY NIGHT MONDAY BRINGING A CHANCE POPS AND SOME QUITE
CHILLY AIR AS 1000-500 MB THICKNESS DROPS TO 540DM ACROSS N MN.
LOOKING LIKE COOL START TO THE UPCOMING WEEK AS WE GET DEEP INTO NW
FLOW.
&&
.AVIATION.../12Z TAF ISSUANCE/
COLD FRONT HAS NOW CLEARED ALL MPX TERMINAL...WITH SFC HIGH
BUILDING IN ITS A WAKE. SEEING PLENTY OF LIFT BEHIND THE FRONT
RESULTING IN TWO BANDS OF PRECIP...ONCE OVER WRN WI AND THE OTHER
FROM NE COLORADO UP TO WRN MN. IT IS THE WRN BATCH OF RAIN THAT
THE NAM AND VARIOUS HI-RES WRF RUNS HAVE PICKED UP ON WELL THIS
MORNING...SO FOLLOWED THESE SOLUTIONS FOR MOVING A BAND OF LIGHT
RAIN ACROSS ALL BUT STC/AXN TODAY. WRN WI TERMINALS WILL LIKELY SEE A
BRIEF BREAK BETWEEN CURRENT RAIN AND THIS WRN BAND OF PRECIP WHICH
WILL MOVE THROUGH THERE IN THE AFTERNOON. HIGH PRESSURE AT THE SFC
IS VERY DRY...SO EXPECT VIS/CIG TO REMAIN VFR THE WHOLE PERIOD.
TONIGHT...SKIES WILL BEGIN TO CLEAR FROM NW TO SE. WINDS WILL BE
NOWHERE NEAR AS STRONG TODAY...BUT WILL TEND TO THE W/NW DEPENDING
ON A TERMINALS LOCATION RELATIVE TO THE RIDGE AXIS.
KMSP...SHOULD START OUT DRY THIS MORNING AS THE FIELD SITS BETWEEN
BANDS OF FORCING. TIMED PRECIP IN TAF PRETTY CLOSE TO THE
NAM...WITH SEVERAL HOURS OF LIGHT RAIN EXPECTED FROM LATE THIS
MORNING THROUGH MUCH OF THE AFTERNOON. DESPITE ALL OF THE
PRECIP...ADVECTION OF VERY DRY AIR IN AT THE LOW LEVELS WILL KEEP
CIGS ABV 060 TODAY.
/OUTLOOK FOR KMSP/
.THURSDAY...VFR. ISOLD AFTN SHRA POSSIBLE. WINDS NW AT 05-10 KTS.
.FRIDAY...VFR. 5-10KT NW WINDS BECOMING SW.
.SATURDAY...VFR. WINDS S AT 10KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BAP/MPG
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
546 AM CDT Wed Sep 12 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Today through Friday...
A band of weak elevated instability ahead of a surface cold front in
central Nebraska and northwest Iowa this morning has fired up a few
very light showers across the northwest corner of the forecast area.
The HRRR indicates these showers may persist just ahead of the
boundary for a few hours before mixing begins to eliminate the
instability, so have added a small chance of very light showers to
the far northwest through late morning. For the rest of the day,
above normal temperatures and breezy south winds can be expected
again, especially across the southwestern corner of the CWA. Surface
low pressure at the base of a deep trough over the northern Rockies
will push eastward into central Kansas today, resulting in the
tighter pressure gradient in our southwest, and could also provide
additional forcing needed to fire up some isolated convection mainly
west of the forecast area late this afternoon. As the main trough
dives to the southeast, the surface cold front will push through
southeast Nebraska and western Iowa, arriving at the northwest
corner of the CWA by 00z. Surface-based instability will build ahead
of the front this afternoon, which may result in isolated convective
initiation along the boundary as it enters the forecast area. Any
isolated development that occurs in central Kansas may also build
eastward during the evening, eventually merging with precipitation
along the cold front. However, surface-based convection will likely
not sustain after sunset, and the bulk of precipitation should occur
behind the surface front as the main wave moves through.
Although showers still look likely through Thursday as the main
trough makes southeastward progress across the CWA, precipitation
chances will decrease as the upper wave weakens and the best energy
transitions further east, towards the Great Lakes region. Have
gradually decreased the chance of precipitation from Thursday
morning through Friday, and also lowered precipitation amounts as
rainfall becomes more scattered. As the wave weakens, it also slows
across the region, so have slowed the southeastward progress of
rainfall chances, especially Thursday night and Friday. Lingering
showers should exit the region altogether by early Friday afternoon.
Temperatures will fall dramatically following cold frontal passage
on Thursday, especially with cloud cover and precipitation filling
in behind the surface front. Highs Thursday may only recover a few
degrees from overnight lows, especially in areas where the surface
front passes during the early morning. Temperatures will be slow to
recover this weekend as the midlevel boundary remains to our
southwest, keeping cooler air entrenched across the region.
Saturday through Tuesday...
A few model solutions break off the southwestern extent of the wave
on Friday, and keep a small disturbance over the Southern High
Plains from Friday night through Saturday. As the southwesterly jet
across the Texas panhandle increases Saturday, the lower pressure
deepens and begins to eject northeastward, possibly bringing
precipitation chances back into our south by early Sunday.
Afterward, another deep trough moves through the central U.S.,
bringing another cold front and additional chances of showers from
Monday morning through Tuesday. Temperatures will have little chance
to rebound back towards normal values early this week before the
next cold front comes through, which indicates mainly below normal
temperatures through the forecast period.
Laflin
&&
.AVIATION...
For the 12Z TAFs, VFR conditions will prevail through much of the
period as southerly winds increase ahead of an advancing cold front.
That cold front is expected to move into the terminals late in the
valid period and and eventually switch winds to the north-northeast.
This will also usher in a good chance for precipitation as well as
lower ceilings, approaching MVFR, in the 06-09Z time frame. The best
chances for rain will come during the day Thursday and it is likely
that the near MVFR conditions will deteriorate as precipitation
increases in intensity and cold air advects into the region aiding a
lowering of cloud cover.
CDB
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
706 AM CDT WED SEP 12 2012
.UPDATE...JUST COMPLETED/SENT A SOMEWHAT SIGNIFICANT UPDATE SOLELY
ADDRESSING THE DAYTIME 12Z-00Z PERIOD...WITH NO CHANGES BEYOND 00Z
MADE FROM THE PREVIOUS MORNING ISSUANCE. STARTING WITH
POPS/WEATHER...AFTER PERUSING THE LATEST GUIDANCE INCLUDING THE
06Z NAM/09Z HRRR/03Z SREF...DECIDED TO SPLIT THE MORNING GRID INTO
TWO 3-HOUR BLOCKS. PRIOR TO 15Z...MOST OF THE CWA SHOULD REMAIN
HIGH AND DRY...AS THE WARM AIR ADVECTION SHOWERS/WEAK STORMS FROM
EARLIER IN THE NIGHT FOCUS MAINLY TO THE EAST...WHILE THE PRIMARY
MID LEVEL FRONTOGENETIC BAND REMAINS WELL TO THE NORTHWEST. THEN
BETWEEN 15Z-18Z...UPPED POPS TO LIKELY 60S-70S ACROSS THE FAR
NORTHWEST CWA AS THE LEADING EDGE OF THIS MID LEVEL SATURATION
SHOULD GET THE MAIN EVENT UNDERWAY. FOR THE AFTERNOON 18Z-00Z
PERIOD LEFT POPS IN A 6-HOUR BLOCK...BUT INCREASED CONSIDERABLY
INTO THE 70 TO NEAR 100 PERCENT RANGE ACROSS ROUGHLY THE NORTHWEST
1/2 OF THE CWA...AS THE LATEST MODELS HAVE SPED UP THE
SOUTHEASTWARD PROGRESSION OF THE RAIN BAND A BIT...INCREASING
CONFIDENCE IN MEASURABLE RAIN BEFORE SUNSET. ON THE OTHER
HAND...MUCH OF THE SOUTHEAST 1/2 OF THE CWA MAY BE LUCKY TO SEE
MUCH OF ANYTHING MEASURABLE THIS AFTERNOON...AND THUS LEFT POPS
PRIMARILY ONLY 20-30 PERCENT...WITH MUCH HIGHER CHANCES OF COURSE
ARRIVING THIS EVENING WHICH IS WELL COVERED IN THE FORECAST.
MOVING ON TO TEMPS...AFTER BLENDING THE 06Z NAM HOURLY TEMPS WITH
THE 00Z CONSALL...ENDED UP SLASHING ACTUAL HIGHS A SOLID 3-6
DEGREES ACROSS MOST OF THE CWA...WITH ONE OF THE BIGGEST CHANGES
NOTED AT PLACES SUCH AS HASTINGS WHICH WAS LOWERED FROM 75 TO 68.
STILL HAVE FAR SOUTHEAST ZONES AROUND BELOIT CLIMBING TO THE MID
80S...BUT EVEN THIS MAY BE A STRETCH IF THE FASTER PROGRESSION OF
THE FRONT EVIDENT IN THE 06Z NAM VERIFIES. FINALLY...INCREASED
WIND SPEEDS A TAD AS WELL...AS NOW EXPECT AN OVERALL GREATER
COVERAGE AND DURATION OF SUSTAINED SPEEDS AT LEAST 20-25 MPH AND
GUSTS TO AROUND 40 MPH. ALTHOUGH A FEW SPOTS COULD BRIEFLY EXCEED
30 MPH SUSTAINED ADVISORY CRITERIA...THIS WOULD LIKELY BE FAR TOO
FLEETING TO JUSTIFY A WIND ADVISORY BUT WILL MENTION NEAR-ADVISORY
SPEEDS IN THE HAZARDOUS WEATHER OUTLOOK.
&&
.PREV DISCUSSION... /ISSUED 556 AM CDT WED SEP 12 2012/
AVIATION...12Z KGRI TAF. A STRONG COLD FRONT HAS PASSED THROUGH
KGRI AND NORTHEAST WINDS WILL QUICKLY GAIN STRENGTH THIS MORNING
AND COULD GUST TO OVER 35 MPH AT TIMES FROM MID MORNING THROUGH
LATE AFTERNOON. MOST OF THE MORNING SHOULD BE DRY WITH INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS AS WE HEAD THROUGH THE
AFTERNOON. THERE HAVE BEEN A FEW SHOWERS AND ISOLATED
THUNDERSTORMS AROUND KGRI EARLIER THIS MORNING AND WE CAN NOT
TOTALLY RULE OUT A LITTLE RAIN AT THE AIRPORT LATER THIS
MORNING...BUT RAIN WILL BE MOST LIKELY AT KGRI BETWEEN 5 PM AND 11
PM THIS EVENING. RAINFALL AMOUNTS BY THE TIME THE RAIN ENDS LATE
TONIGHT COULD EASILY BE OVER ONE HALF INCH. THERE COULD ALSO BE A
FEW CLAPS OF THUNDER BUT NOTHING STRONG OR SEVERE.
PREV DISCUSSION... /ISSUED 356 AM CDT WED SEP 12 2012/
SHORT TERM...THROUGH FRIDAY NIGHT. CLEARLY THE PARAMOUNT ISSUE
OVER THE NEXT 72 HOURS CONCERNS PRECIP TRENDS DURING THE FIRST 24
HOURS...INCLUDING HOW MUCH RAIN WILL FALL AND WHEN THE MAJORITY OF
IT WILL START/END. ONE THING IS CERTAIN...ALTHOUGH THE MAJORITY OF
THE CWA WILL PROBABLY NOT MEASURE OVER 1 INCH...THIS IS STILL
LOOKING LIKE ONE OF THE MOST WIDESPREAD CHANCES FOR AT LEAST
0.30-0.90 THAT MUCH OF THE AREA HAS SEEN IN AWHILE...ESPECIALLY
NEAR/NORTH OF I-80. SECONDARY CONCERNS INCLUDE A VERY TRICKY TEMP
FORECAST TODAY.
07Z OBJECTIVE SURFACE ANALYSIS AND RADAR IMAGERY PLACES THE WELL-
ADVERTISED COLD FRONT ESSENTIALLY BISECTING THE CWA FROM SW-
NE...WITH THE LEADING EDGE ROUGHLY ALONG A BEAVER CITY-GRAND
ISLAND-COLUMBUS LINE AND SLOWLY BUT STEADILY ADVANCING SOUTHEAST
WITH TIME. THIS FRONT IS ANCHORED TO A 1005MB LOW ALONG THE
SOUTHERN CO/KS BORDER. IN THE WAKE OF THIS FRONT...NORTHERLY WIND
GUSTS HAVE INCREASED WELL INTO THE 25-35 MPH RANGE AT PLACES SUCH
AS ORD AND BROKEN BOW...WHILE AHEAD OF THE FRONT...SOUTHERLY GUSTS
OF AT LEAST 15-25 MPH CONTINUE IN MANY AREAS. THESE BREEZES...IN
TANDEM WITH CONSIDERABLE MID/HIGH CLOUDS HAVE KEPT OVERNIGHT TEMPS
WELL INTO THE 65-75 RANGE THUS FAR CWA-WIDE. ALOFT...WATER VAPOR
IMAGERY AND SHORT TERM MODEL DATA CONFIRMS BROAD WEST-SOUTHWEST
FLOW OVER THE CENTRAL PLAINS...WHILE WELL OFF TO THE NORTH A
POWERFUL VORT MAX OVER NORTHERN MANITOBA ANCHORS A TROUGH AXIS
TRAILING SOUTH INTO THE DAKOTAS/NORTHERN ROCKIES...AND WELL TO THE
SOUTHEAST OF THE CWA A BROAD RIDGE DOMINATES MUCH OF THE SOUTHEAST
CONUS.
STARTING OFF WITH THE EARLY MORNING PERIOD THROUGH SUNRISE...THE
MOST IMMEDIATE ISSUE IS THE RECENT DEVELOPMENT OF ISOLATED TO
SCATTERED SHOWER/FAIRLY WEAK THUNDERSTORM ACTIVITY MAINLY ACROSS
THE FAR NORTHEAST CWA...BUT ALSO STARTING UP OVER SOUTHWEST AND
SOUTHEAST NEB ZONES AS WELL. THIS SOMEWHAT UNEXPECTED PRE-DAWN
FLARE UP WAS NOT WELL CAPTURED BY MOST MODELS...BUT HAS BEEN
SUGGESTED FOR THE LAST SEVERAL HOURLY RUNS OF THE HRRR.
BASICALLY...THIS ACTIVITY SEEMS BEST TIED TO THE WARM AIR/THETA-E
ADVECTION ZONE NEAR AND JUST AHEAD OF THE 850MB COLD FRONT SLICING
INTO THE CWA...AND WITHIN THE AXIS OF A 45-55KT 850MB LOW LEVEL
JET. SPC HOURLY MESO-ANALYSIS ALONG WITH THE 06Z NAM INDICATES
THAT EVEN PEA SIZE HAIL SHOULD BE HARD TO COME BY GIVEN ELEVATED
MUCAPE IN THE 850-700MB LAYER AVERAGING NO MORE THAN 100-200 J/KG.
WILL MAKE A LAST MINUTE DECISION BEFORE FORECAST ISSUANCE
REGARDING HOW TO HANDLE THIS PRE-DAWN ACTIVITY IN THE GRIDS.
TURNING TO THE DAYTIME 12Z-00Z PERIOD...GENERALLY STUCK FAIRLY
CLOSELY TO THE THE THEME OF THE PREVIOUS FORECAST...BUT DUE TO
SOME UNCERTAINTY IN THE TIMING DETAILS OPTED TO NOT SPLIT THE
DAYTIME POP/WEATHER GRIDS INTO MORE THAN TWO 6-HOUR BLOCKS AT THIS
TIME. DESPITE THE EARLY MORNING ACTIVITY ONGOING OUT THERE...WANT
TO EMPHASIZE THAT THE MAJORITY OF THE CWA...ESPECIALLY THE
SOUTHEAST 2/3 WILL LIKELY SEE VERY LITTLE IF ANY MEASURABLE
RAINFALL THROUGH THE DAYTIME HOURS. STARTING WITH THE MORNING
12Z-18Z BLOCK...WILL LEAN TOWARD THE HRRR SUGGESTION THAT MOST OF
THIS PRE-DAWN WARM AIR ADVECTION DRIVEN CONVECTION WILL EXIT EAST
OF THE CWA OR AT LEAST DIMINISH IN COVERAGE BY SUNRISE OR SHORTLY
AFTER. THIS LEAVES THE MAIN FOCUS FOR MORNING PRECIPITATION ACROSS
FAR NORTHWEST PORTIONS OF THE CWA IN CLOSEST PROXIMITY TO THE
SOUTHEAST-ADVANCING MID LEVEL FRONTOGENETIC ZONE ALIGNED WITHIN
THE ENTRANCE REGION OF A 80-100KT 300MB JET STREAK RUNNING FROM
THE DAKOTAS INTO QUEBEC. AT LEAST FOR NOW...KEPT POPS DURING THE
12Z-18Z TIME FRAME BELOW LIKELY TERRITORY...BUT WITH 30-50 POPS
ACROSS THE NORTHWEST HALF TAPERING DOWN TO SLIGHT CHANCE SPRINKLE
WORDING ACROSS THE SOUTHEAST. FOR THE AFTERNOON 18Z-00Z
BLOCK...MAY HAVE NOT GONE HIGH ENOUGH WITH POPS GIVEN LATEST MODEL
TRENDS INCLUDING 06Z NAM...BUT HAVE AT LEAST 40-60 POPS GOING
ACROSS MUCH OF THE NORTHWEST HALF OF THE CWA...AND 70S-90S FAR
NORTH. MOST OF THE RAIN WILL BE TIED TO THE EXACT PLACEMENT OF THE
FAIRLY NARROW FRONTOGENETIC BAND...RESULTING IN A SLOWLY ADVANCING
BUT SHARP CUTOFF FROM STEADY LIGHT/MODERATE RAINFALL TO NOTHING.
KEPT THUNDER WORDING AS ISOLATED THROUGH THE DAY...AS EVEN MODEST
ELEVATED INSTABILITY SHOULD GRADUALLY DECREASE WITH TIME...AND ANY
RISK FOR MARGINALLY STRONG STORMS NEAR THE ACTUAL SURFACE COLD
FRONT DURING THE AFTERNOON/EARLY EVENING SHOULD REMAIN AT LEAST
1-2 COUNTIES SOUTH/SOUTHEAST OF OUR KS ZONES ACROSS THE TOP/ICT
CWA/S. TURNING TO OTHER ELEMENTS...HIGH TEMPS WILL BE VERY TRICKY
DAYS WITH MOST AREAS SEEING STEADY/SLOWLY FALLING TEMPS BEHIND THE
COLD FRONT. TOOK A BEST STAB THAT ENDED UP CLOSE TO PREVIOUS
FORECAST...WITH DAYLIGHT HIGHS RANGING FROM MID 60S FAR NORTHWEST
TO LOW-MID 70S TRI-CITIES AREA AND UPPER 80S FAR SOUTHEAST.
HOWEVER...ACTUAL HOURLY TEMPS ACROSS MUCH OF THE NORTHWEST 1/2 OF
THE CWA THIS AFTERNOON WILL ONLY BE IN THE 50S/60S...SO THE HIGH
TEMP GRID WILL BE A BIT MISLEADING. AS FOR SURFACE WIND
SPEEDS...ANTICIPATE SPEEDS TO AVERAGE AT LEAST 5 MPH BELOW
ADVISORY LEVELS...BUT AS THE FRONT PUSHES IN SHOULD EASILY SEE
SUSTAINED SPEEDS OF 20-25 MPH AND GUSTS UP TO AROUND 35 MPH AND
EVEN AS HIGH AS 40 MPH ON A HIT AND MISS BASIS.
TONIGHT...THIS IS STILL LOOKING LIKE THE MAIN EVENT FOR MOST OF
THE CWA...ESPECIALLY THE SOUTHEAST 2/3...AS THE STRENGTHENING MID
LEVEL FRONTOGENETIC BAND SLIDES SOUTHEAST OVER THE AREA...AND INDUCES
AN INCREASINGLY ORGANIZED BAND OF STEADY LIGHT TO MODERATE AND
POTENTIALLY BRIEFLY HEAVY RAIN. SPLIT THE POP/WEATHER GRIDS INTO
6-HOUR BLOCKS...BUT AT LEAST TOUCHED ALL AREAS SOUTH OF AN ELWOOD-
GRAND ISLAND-FULLERTON LINE WITH 80-90 POPS AT SOME POINT...WITH
LESSER CHANCES TAPERING OFF ACROSS NORTHWEST ZONES AS THE NIGHT
WEARS ON AND PLACES LIKE ORD/GOTHENBURG LIKELY COMPLETELY DONE
WITH PRECIP WELL BEFORE MIDNIGHT. TEMP-WISE...LOWERED LOWS ROUGHLY
3 DEGREES FROM PREVIOUS PER LATEST GUIDANCE...RANGING FROM MID 40S
NORTHWEST TO LOW 50S SOUTHEAST.
THURSDAY...LEFT 20-60 POPS GOING IN THE MORNING BLOCK FOR AREAS
GENERALLY SOUTH OF A PHILLIPSBURG-GENEVA LINE...BUT THE LATEST 06Z
NAM WOULD SUGGEST THAT VIRTUALLY THE ENTIRE CWA MAY BE PRECIP FREE
BY SUNRISE AS IT MOVES THE MID LEVEL BANDING OUT FASTER THAN
PREVIOUSLY ADVERTISED. NO MATTER WHAT...THE ENTIRE CWA WILL MOST
CERTAINLY BE DRY BY THE AFTERNOON HOURS...WITH MOSTLY CLEAR SKIES
INVADING FROM NORTH TO SOUTH AS THE DAY WEARS ON. ASSUMING THAT AT
LEAST A FEW HOURS OF SUNSHINE MATERIALIZES...ESPECIALLY NORTHERN
AREAS SHOULD WARM FAIRLY EFFICIENTLY. NUDGED UP HIGHS 1-3 DEGREES
IN MOST AREAS...WITH MOST NEB ZONES IN THE 71-74 RANGE AND FAR
SOUTHEAST ZONES MORE SO 69-71 WHERE CLOUDS WILL LINGER THE
LONGEST.
BEFORE MOVING ON TO THE DRY LATTER PART OF THE SHORT TERM
PERIOD...A FEW COMMENTS ABOUT RAINFALL AMOUNTS DURING THE NEXT 24-30
HOURS. TAKING LATEST BLEND OF MODEL CONSENSUS ALONG WITH HPC
GUIDANCE...AM NOW ADVERTISING WIDESPREAD QPF RANGING FROM
0.40-0.90 ACROSS THE MAJORITY OF THE CWA...WITH THE BEST POTENTIAL
FOR HIGHER AMOUNTS IN THE 1 INCH TO 1.4 RANGE TARGETING AREAS
SOUTHEAST OF A YORK TO OSBORNE LINE.
THURS NIGHT...COOL HIGH PRESSURE SETTLES INTO THE REGION...AND
ALTHOUGH WET GROUND SHOULD MITIGATE A SHARP TEMP DROP...KEPT LOWS
ON THE CHILLY SIDE AND CLOSE TO PREVIOUS FORECAST WITH MOST AREAS
IN THE 40-45 RANGE...AND EVEN SOME UPPER 30S NOW IN FAVORED COLDER
SPOTS SUCH AS VALLEY/WESTERN DAWSON COUNTIES. UNLESS THINGS TREND
ANOTHER 2-4 DEGREES COLDER...SHOULD BE FREE FROM EARLY SEASON
FROST CONCERNS.
FRIDAY IS LOOKING QUITE PLEASANT OVERALL WITH LIGHT BREEZES AS THE
SURFACE RIDGE AXIS SLOWLY SLIDES EAST...ALONG WITH PLENTY OF
SUNSHINE AS MID LEVEL RIDGING EXTENDS EAST OUT OF THE CENTRAL
ROCKIES. KEPT HIGHS SIMILAR TO PREVIOUS FORECAST WITH MOST AREAS
73-76...ALTHOUGH COULD SEE SOME AREAS A FEW DEGREES HIGHER THAN
THIS PER LATEST 06Z NAM TRENDS.
FRIDAY NIGHT...ANY PRECIP ASSOCIATED WITH A SOUTHERN STREAM WAVE
SHOULD REMAIN NO CLOSER THAN THE KS/OK BORDER AREA...PAVING THE
WAY FOR ANOTHER MAINLY CLEAR NIGHT AS LIGHT BUT STEADY SOUTH WINDS
BECOME ESTABLISHED. CHANGED LOWS LITTLE WITH MAINLY MID-UPPER 40S.
LONG TERM...SATURDAY THROUGH TUESDAY. DRY WEATHER IS EXPECTED OVER
THE WEEKEND AND THEN THERE IS A CHANCE OF THUNDERSTORMS ON MONDAY
AS A COLD FRONT TRACKS ACROSS THE PLAINS. HIGH TEMPERATURES WILL BE
VERY PLEASANT THIS WEEKEND WITH HIGHS ON SATURDAY IN THE MID 70S AND
THEN AROUND 80 FOR MOST AREAS ON SUNDAY. TEMPERATURES WILL COOL
BEHIND THE FRONT ON MONDAY FALLING BACK INTO THE UPPER 60S TO LOWER
70S AND SHOULD REMAIN CLOSE TO THAT ON TUESDAY.
THE UPPER LEVEL PATTERN WILL BE FAIRLY ZONAL OVER THE WEEKEND AND
THEN AN UPPER TROUGH WILL SKIRT THROUGH THE NORTHERN PLAINS ON
MONDAY AND INTO THE GREAT LAKES BY TUESDAY. MOST OF THE DYNAMICS
ASSOCIATED WITH THIS SYSTEM SHOULD BE WELL NORTHEAST OF OUR FORECAST
AREA THUS LIMITING OUR PRECIPITATION CHANCES. CONSALL SEEMS VERY
OVERDONE WITH POPS IN THE 50 TO 60 PERCENT RANGE ON MONDAY. THE NEW
00Z ECMWF CAME IN DRY. OUR PREVIOUS FORECAST WAS ONLY CALLING FOR
SLIGHT POPS AT AROUND 20 PERCENT. WILL INCREASE POPS INTO THE LOW
END CHANCE CATEGORY AT AROUND 30 PERCENT...BUT NOT WILLING TO GO
HIGHER AT THIS POINT IN TIME GIVEN THE NORTHERN TRACK OF THE UPPER
DYNAMICS AND LACK OF SUPPORT IN THE LATEST 00Z ECMWF. THIS SHOULD BE
A QUICK HITTING SYSTEM WITH THE SFC HIGH ALREADY LOCATED EAST OF US
BY TUESDAY ALLOWING FOR A RETURN OF WEAK SOUTHERLY FLOW AND DRY
WEATHER. LATEST MODEL RUNS TONIGHT HAVE BEEN KEEPING THE
INSTABILITY ASSOCIATED WITH THE MONDAY SYSTEM ACROSS KANSAS AND WILL
JUST BE CALLING FOR RAIN SHOWERS OVER MOST NEBRASKA ZONES GIVEN THE
LACK OF INSTABILITY FOR THUNDERSTORMS. WILL CONTINUE TO KEEP A
MENTION OF ISOLATED THUNDERSTORMS SOUTH OF A HEBRON TO ALMA LINE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE/SHORT TERM...PFANNKUCH
LONG TERM/AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
611 AM CDT WED SEP 12 2012
.AVIATION...
12Z TAFS FOR KOFK...KOMA AND KLNK.
DECENT FORCING IS EXPECTED TODAY INTO EARLY TONIGHT NEAR AND
BEHIND A COLD FRONT THAT WILL PRESS SOUTHEAST ACROSS THE KLNK AND
KOMA VICINITIES BY MIDDAY. WEAK OUTFLOW COULD BRING VARIABLE
WINDS TO KOMA AND KLNK THIS MORNING BUT IN GENERAL A BRISK NORTH
OR NORTHEAST WIND WAS FORECAST AT TAF SITES BY THIS AFTERNOON.
THE FORCING SHOULD BRING AN INCREASE IN SHOWERS TO THE AREA BUT VERY
DRY LOW LEVEL AIR CREATE UNCERTAINTIES TO HOW LOW VISIBILITIES OR
CEILINGS WILL DROP. THE ISOLATED SHOWERS AND EVEN A RUMBLE OF
THUNDER THIS MORNING WAS NOT EXPECTED TO BE MAIN PRECIP
AREA. THE MAIN OUTBREAK SHOULD SPREAD OR DEVELOP INTO NORTHEAST
NEBRASKA THROUGH THIS AFTERNOON AND THEN SETTLE SOUTHEAST ACROSS
KLNK/KOMA THIS EVENING. MODEL FORECAST SOUNDINGS POINTED AT KLNK
DEVELOPING THE LOWEST CIGS WITH THIS RAIN EVENT AND 12Z TAF FORECAST
REFLECTED THAT. HOWEVER...A PERIOD OF LOWER CIGS/VSBYS ALSO
POSSIBLE AT KOFK AND KOMA LATER TODAY/EARLY TONIGHT AS RAIN AREA
INCREASES. CONDITIONS SHOULD IMPROVE FROM NORTH TO SOUTH TONIGHT.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 245 AM CDT WED SEP 12 2012/
DISCUSSION...
COLD FRONT EXTENDED FROM NORTHWEST IOWA ACROSS NORTHEAST NEBRASKA
INTO SOUTH CENTRAL NEBRASKA ALONG A KSUX TO KEAR LINE AT 07Z.
SCATTERED SHOWERS AHEAD OF THE FRONT HAVE BECOME MORE NUMEROUS
DURING THE PAST HOUR OVER SOUTHEAST NEBRASKA INTO SOUTHWEST IOWA.
00Z GFS AND 04Z HRRR APPEAR TO BE SIMILAR IN HAVING THE FRONT NEAR
A KOMA TO KHJH LINE BY 12Z...A BIT FASTER THAN THE 00Z NAM.
WILL ADD CHANCE OF SHOWERS AND ISOLATED THUNDER TO AREAS SOUTH OF
THE FRONT THIS MORNING BASED ON RADAR TRENDS AND SHORT RANGE
MODELS. WILL ALSO LIKELY TREND HIGHS TODAY TOWARD THE SOMEWHAT
COOLER GFS GUIDANCE BASED ON FASTER TIMING OF THAT MODEL.
OTHERWISE...STILL LOOKS GOOD FOR WIDESPREAD RAIN ACROSS MUCH OF
THE AREA TONIGHT WITH SYSTEM MOVING OUT OF SOUTHEAST AREAS
THURSDAY MORNING. FAIR AND DRY AFTER THAT WITH COOLER TEMPERATURES
HANGING AROUND FOR A CHANGE.
IN THE EXTENDED...AREA REMAINS UNDER THE INFLUENCE OF COOLER
NORTHWEST FLOW WITH ANOTHER STRONG TROUGH MOVING THROUGH THE
REGION EARLY NEXT WEEK. STILL SOME CHANCE OF SHOWERS WITH COLD
FRONT ON MONDAY WITH LOW POPS MAINTAINED FOR THAT PERIOD. SOME
DIFFERENCES BETWEEN THE GFS AND EURO IN HANDLING THIS FASTER FLOW
SO WILL HAVE TO SEE HOW CONSISTENT FUTURE MODEL RUNS BEHAVE.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
556 AM CDT WED SEP 12 2012
.AVIATION...12Z KGRI TAF. A STRONG COLD FRONT HAS PASSED THROUGH
KGRI AND NORTHEAST WINDS WILL QUICKLY GAIN STRENGTH THIS MORNING
AND COULD GUST TO OVER 35 MPH AT TIMES FROM MID MORNING THROUGH
LATE AFTERNOON. MOST OF THE MORNING SHOULD BE DRY WITH INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS AS WE HEAD THROUGH THE
AFTERNOON. THERE HAVE BEEN A FEW SHOWERS AND ISOLATED
THUNDERSTORMS AROUND KGRI EARLIER THIS MORNING AND WE CAN NOT
TOTALLY RULE OUT A LITTLE RAIN AT THE AIRPORT LATER THIS
MORNING...BUT RAIN WILL BE MOST LIKELY AT KGRI BETWEEN 5 PM AND 11
PM THIS EVENING. RAINFALL AMOUNTS BY THE TIME THE RAIN ENDS LATE
TONIGHT COULD EASILY BE OVER ONE HALF INCH. THERE COULD ALSO BE A
FEW CLAPS OF THUNDER BUT NOTHING STRONG OR SEVERE.
&&
.PREV DISCUSSION... /ISSUED 356 AM CDT WED SEP 12 2012/
SHORT TERM...THROUGH FRIDAY NIGHT. CLEARLY THE PARAMOUNT ISSUE
OVER THE NEXT 72 HOURS CONCERNS PRECIP TRENDS DURING THE FIRST 24
HOURS...INCLUDING HOW MUCH RAIN WILL FALL AND WHEN THE MAJORITY OF
IT WILL START/END. ONE THING IS CERTAIN...ALTHOUGH THE MAJORITY OF
THE CWA WILL PROBABLY NOT MEASURE OVER 1 INCH...THIS IS STILL
LOOKING LIKE ONE OF THE MOST WIDESPREAD CHANCES FOR AT LEAST
0.30-0.90 THAT MUCH OF THE AREA HAS SEEN IN AWHILE...ESPECIALLY
NEAR/NORTH OF I-80. SECONDARY CONCERNS INCLUDE A VERY TRICKY TEMP
FORECAST TODAY.
07Z OBJECTIVE SURFACE ANALYSIS AND RADAR IMAGERY PLACES THE WELL-
ADVERTISED COLD FRONT ESSENTIALLY BISECTING THE CWA FROM SW-
NE...WITH THE LEADING EDGE ROUGHLY ALONG A BEAVER CITY-GRAND
ISLAND-COLUMBUS LINE AND SLOWLY BUT STEADILY ADVANCING SOUTHEAST
WITH TIME. THIS FRONT IS ANCHORED TO A 1005MB LOW ALONG THE
SOUTHERN CO/KS BORDER. IN THE WAKE OF THIS FRONT...NORTHERLY WIND
GUSTS HAVE INCREASED WELL INTO THE 25-35 MPH RANGE AT PLACES SUCH
AS ORD AND BROKEN BOW...WHILE AHEAD OF THE FRONT...SOUTHERLY GUSTS
OF AT LEAST 15-25 MPH CONTINUE IN MANY AREAS. THESE BREEZES...IN
TANDEM WITH CONSIDERABLE MID/HIGH CLOUDS HAVE KEPT OVERNIGHT TEMPS
WELL INTO THE 65-75 RANGE THUS FAR CWA-WIDE. ALOFT...WATER VAPOR
IMAGERY AND SHORT TERM MODEL DATA CONFIRMS BROAD WEST-SOUTHWEST
FLOW OVER THE CENTRAL PLAINS...WHILE WELL OFF TO THE NORTH A
POWERFUL VORT MAX OVER NORTHERN MANITOBA ANCHORS A TROUGH AXIS
TRAILING SOUTH INTO THE DAKOTAS/NORTHERN ROCKIES...AND WELL TO THE
SOUTHEAST OF THE CWA A BROAD RIDGE DOMINATES MUCH OF THE SOUTHEAST
CONUS.
STARTING OFF WITH THE EARLY MORNING PERIOD THROUGH SUNRISE...THE
MOST IMMEDIATE ISSUE IS THE RECENT DEVELOPMENT OF ISOLATED TO
SCATTERED SHOWER/FAIRLY WEAK THUNDERSTORM ACTIVITY MAINLY ACROSS
THE FAR NORTHEAST CWA...BUT ALSO STARTING UP OVER SOUTHWEST AND
SOUTHEAST NEB ZONES AS WELL. THIS SOMEWHAT UNEXPECTED PRE-DAWN
FLARE UP WAS NOT WELL CAPTURED BY MOST MODELS...BUT HAS BEEN
SUGGESTED FOR THE LAST SEVERAL HOURLY RUNS OF THE HRRR.
BASICALLY...THIS ACTIVITY SEEMS BEST TIED TO THE WARM AIR/THETA-E
ADVECTION ZONE NEAR AND JUST AHEAD OF THE 850MB COLD FRONT SLICING
INTO THE CWA...AND WITHIN THE AXIS OF A 45-55KT 850MB LOW LEVEL
JET. SPC HOURLY MESO- ANALYSIS ALONG WITH THE 06Z NAM INDICATES
THAT EVEN PEA SIZE HAIL SHOULD BE HARD TO COME BY GIVEN ELEVATED
MUCAPE IN THE 850-700MB LAYER AVERAGING NO MORE THAN 100-200 J/KG.
WILL MAKE A LAST MINUTE DECISION BEFORE FORECAST ISSUANCE
REGARDING HOW TO HANDLE THIS PRE-DAWN ACTIVITY IN THE GRIDS.
TURNING TO THE DAYTIME 12Z-00Z PERIOD...GENERALLY STUCK FAIRLY
CLOSELY TO THE THE THEME OF THE PREVIOUS FORECAST...BUT DUE TO
SOME UNCERTAINTY IN THE TIMING DETAILS OPTED TO NOT SPLIT THE
DAYTIME POP/WEATHER GRIDS INTO MORE THAN TWO 6-HOUR BLOCKS AT THIS
TIME. DESPITE THE EARLY MORNING ACTIVITY ONGOING OUT THERE...WANT
TO EMPHASIZE THAT THE MAJORITY OF THE CWA...ESPECIALLY THE
SOUTHEAST 2/3 WILL LIKELY SEE VERY LITTLE IF ANY MEASURABLE
RAINFALL THROUGH THE DAYTIME HOURS. STARTING WITH THE MORNING
12Z-18Z BLOCK...WILL LEAN TOWARD THE HRRR SUGGESTION THAT MOST OF
THIS PRE-DAWN WARM AIR ADVECTION DRIVEN CONVECTION WILL EXIT EAST
OF THE CWA OR AT LEAST DIMINISH IN COVERAGE BY SUNRISE OR SHORTLY
AFTER. THIS LEAVES THE MAIN FOCUS FOR MORNING PRECIPITATION ACROSS
FAR NORTHWEST PORTIONS OF THE CWA IN CLOSEST PROXIMITY TO THE
SOUTHEAST-ADVANCING MID LEVEL FRONTOGENETIC ZONE ALIGNED WITHIN
THE ENTRANCE REGION OF A 80-100KT 300MB JET STREAK RUNNING FROM
THE DAKOTAS INTO QUEBEC. AT LEAST FOR NOW...KEPT POPS DURING THE
12Z-18Z TIME FRAME BELOW LIKELY TERRITORY...BUT WITH 30-50 POPS
ACROSS THE NORTHWEST HALF TAPERING DOWN TO SLIGHT CHANCE SPRINKLE
WORDING ACROSS THE SOUTHEAST. FOR THE AFTERNOON 18Z-00Z
BLOCK...MAY HAVE NOT GONE HIGH ENOUGH WITH POPS GIVEN LATEST MODEL
TRENDS INCLUDING 06Z NAM...BUT HAVE AT LEAST 40-60 POPS GOING
ACROSS MUCH OF THE NORTHWEST HALF OF THE CWA...AND 70S-90S FAR
NORTH. MOST OF THE RAIN WILL BE TIED TO THE EXACT PLACEMENT OF THE
FAIRLY NARROW FRONTOGENETIC BAND...RESULTING IN A SLOWLY ADVANCING
BUT SHARP CUTOFF FROM STEADY LIGHT/MODERATE RAINFALL TO NOTHING.
KEPT THUNDER WORDING AS ISOLATED THROUGH THE DAY...AS EVEN MODEST
ELEVATED INSTABILITY SHOULD GRADUALLY DECREASE WITH TIME...AND ANY
RISK FOR MARGINALLY STRONG STORMS NEAR THE ACTUAL SURFACE COLD
FRONT DURING THE AFTERNOON/EARLY EVENING SHOULD REMAIN AT LEAST
1-2 COUNTIES SOUTH/SOUTHEAST OF OUR KS ZONES ACROSS THE TOP/ICT
CWA/S. TURNING TO OTHER ELEMENTS...HIGH TEMPS WILL BE VERY TRICKY
DAYS WITH MOST AREAS SEEING STEADY/SLOWLY FALLING TEMPS BEHIND THE
COLD FRONT. TOOK A BEST STAB THAT ENDED UP CLOSE TO PREVIOUS
FORECAST...WITH DAYLIGHT HIGHS RANGING FROM MID 60S FAR NORTHWEST
TO LOW-MID 70S TRI-CITIES AREA AND UPPER 80S FAR SOUTHEAST.
HOWEVER...ACTUAL HOURLY TEMPS ACROSS MUCH OF THE NORTHWEST 1/2 OF
THE CWA THIS AFTERNOON WILL ONLY BE IN THE 50S/60S...SO THE HIGH
TEMP GRID WILL BE A BIT MISLEADING. AS FOR SURFACE WIND
SPEEDS...ANTICIPATE SPEEDS TO AVERAGE AT LEAST 5 MPH BELOW
ADVISORY LEVELS...BUT AS THE FRONT PUSHES IN SHOULD EASILY SEE
SUSTAINED SPEEDS OF 20-25 MPH AND GUSTS UP TO AROUND 35 MPH AND
EVEN AS HIGH AS 40 MPH ON A HIT AND MISS BASIS.
TONIGHT...THIS IS STILL LOOKING LIKE THE MAIN EVENT FOR MOST OF
THE CWA...ESPECIALLY THE SOUTHEAST 2/3...AS THE STRENGTHENING MID
LEVEL FRONTOGENETIC BAND SLIDES SOUTHEAST OVER THE AREA...AND INDUCES
AN INCREASINGLY ORGANIZED BAND OF STEADY LIGHT TO MODERATE AND
POTENTIALLY BRIEFLY HEAVY RAIN. SPLIT THE POP/WEATHER GRIDS INTO
6-HOUR BLOCKS...BUT AT LEAST TOUCHED ALL AREAS SOUTH OF AN ELWOOD-
GRAND ISLAND-FULLERTON LINE WITH 80-90 POPS AT SOME POINT...WITH
LESSER CHANCES TAPERING OFF ACROSS NORTHWEST ZONES AS THE NIGHT
WEARS ON AND PLACES LIKE ORD/GOTHENBURG LIKELY COMPLETELY DONE
WITH PRECIP WELL BEFORE MIDNIGHT. TEMP-WISE...LOWERED LOWS ROUGHLY
3 DEGREES FROM PREVIOUS PER LATEST GUIDANCE...RANGING FROM MID 40S
NORTHWEST TO LOW 50S SOUTHEAST.
THURSDAY...LEFT 20-60 POPS GOING IN THE MORNING BLOCK FOR AREAS
GENERALLY SOUTH OF A PHILLIPSBURG-GENEVA LINE...BUT THE LATEST 06Z
NAM WOULD SUGGEST THAT VIRTUALLY THE ENTIRE CWA MAY BE PRECIP FREE
BY SUNRISE AS IT MOVES THE MID LEVEL BANDING OUT FASTER THAN
PREVIOUSLY ADVERTISED. NO MATTER WHAT...THE ENTIRE CWA WILL MOST
CERTAINLY BE DRY BY THE AFTERNOON HOURS...WITH MOSTLY CLEAR SKIES
INVADING FROM NORTH TO SOUTH AS THE DAY WEARS ON. ASSUMING THAT AT
LEAST A FEW HOURS OF SUNSHINE MATERIALIZES...ESPECIALLY NORTHERN
AREAS SHOULD WARM FAIRLY EFFICIENTLY. NUDGED UP HIGHS 1-3 DEGREES
IN MOST AREAS...WITH MOST NEB ZONES IN THE 71-74 RANGE AND FAR
SOUTHEAST ZONES MORE SO 69-71 WHERE CLOUDS WILL LINGER THE
LONGEST.
BEFORE MOVING ON TO THE DRY LATTER PART OF THE SHORT TERM
PERIOD...A FEW COMMENTS ABOUT RAINFALL AMOUNTS DURING THE NEXT 24-30
HOURS. TAKING LATEST BLEND OF MODEL CONSENSUS ALONG WITH HPC
GUIDANCE...AM NOW ADVERTISING WIDESPREAD QPF RANGING FROM
0.40-0.90 ACROSS THE MAJORITY OF THE CWA...WITH THE BEST POTENTIAL
FOR HIGHER AMOUNTS IN THE 1 INCH TO 1.4 RANGE TARGETING AREAS
SOUTHEAST OF A YORK TO OSBORNE LINE.
THURS NIGHT...COOL HIGH PRESSURE SETTLES INTO THE REGION...AND
ALTHOUGH WET GROUND SHOULD MITIGATE A SHARP TEMP DROP...KEPT LOWS
ON THE CHILLY SIDE AND CLOSE TO PREVIOUS FORECAST WITH MOST AREAS
IN THE 40-45 RANGE...AND EVEN SOME UPPER 30S NOW IN FAVORED COLDER
SPOTS SUCH AS VALLEY/WESTERN DAWSON COUNTIES. UNLESS THINGS TREND
ANOTHER 2-4 DEGREES COLDER...SHOULD BE FREE FROM EARLY SEASON
FROST CONCERNS.
FRIDAY IS LOOKING QUITE PLEASANT OVERALL WITH LIGHT BREEZES AS THE
SURFACE RIDGE AXIS SLOWLY SLIDES EAST...ALONG WITH PLENTY OF
SUNSHINE AS MID LEVEL RIDGING EXTENDS EAST OUT OF THE CENTRAL
ROCKIES. KEPT HIGHS SIMILAR TO PREVIOUS FORECAST WITH MOST AREAS
73-76...ALTHOUGH COULD SEE SOME AREAS A FEW DEGREES HIGHER THAN
THIS PER LATEST 06Z NAM TRENDS.
FRIDAY NIGHT...ANY PRECIP ASSOCIATED WITH A SOUTHERN STREAM WAVE
SHOULD REMAIN NO CLOSER THAN THE KS/OK BORDER AREA...PAVING THE
WAY FOR ANOTHER MAINLY CLEAR NIGHT AS LIGHT BUT STEADY SOUTH WINDS
BECOME ESTABLISHED. CHANGED LOWS LITTLE WITH MAINLY MID-UPPER 40S.
LONG TERM...SATURDAY THROUGH TUESDAY. DRY WEATHER IS EXPECTED OVER
THE WEEKEND AND THEN THERE IS A CHANCE OF THUNDERSTORMS ON MONDAY
AS A COLD FRONT TRACKS ACROSS THE PLAINS. HIGH TEMPERATURES WILL BE
VERY PLEASANT THIS WEEKEND WITH HIGHS ON SATURDAY IN THE MID 70S AND
THEN AROUND 80 FOR MOST AREAS ON SUNDAY. TEMPERATURES WILL COOL
BEHIND THE FRONT ON MONDAY FALLING BACK INTO THE UPPER 60S TO LOWER
70S AND SHOULD REMAIN CLOSE TO THAT ON TUESDAY.
THE UPPER LEVEL PATTERN WILL BE FAIRLY ZONAL OVER THE WEEKEND AND
THEN AN UPPER TROUGH WILL SKIRT THROUGH THE NORTHERN PLAINS ON
MONDAY AND INTO THE GREAT LAKES BY TUESDAY. MOST OF THE DYNAMICS
ASSOCIATED WITH THIS SYSTEM SHOULD BE WELL NORTHEAST OF OUR FORECAST
AREA THUS LIMITING OUR PRECIPITATION CHANCES. CONSALL SEEMS VERY
OVERDONE WITH POPS IN THE 50 TO 60 PERCENT RANGE ON MONDAY. THE NEW
00Z ECMWF CAME IN DRY. OUR PREVIOUS FORECAST WAS ONLY CALLING FOR
SLIGHT POPS AT AROUND 20 PERCENT. WILL INCREASE POPS INTO THE LOW
END CHANCE CATEGORY AT AROUND 30 PERCENT...BUT NOT WILLING TO GO
HIGHER AT THIS POINT IN TIME GIVEN THE NORTHERN TRACK OF THE UPPER
DYNAMICS AND LACK OF SUPPORT IN THE LATEST 00Z ECMWF. THIS SHOULD BE
A QUICK HITTING SYSTEM WITH THE SFC HIGH ALREADY LOCATED EAST OF US
BY TUESDAY ALLOWING FOR A RETURN OF WEAK SOUTHERLY FLOW AND DRY
WEATHER. LATEST MODEL RUNS TONIGHT HAVE BEEN KEEPING THE
INSTABILITY ASSOCIATED WITH THE MONDAY SYSTEM ACROSS KANSAS AND WILL
JUST BE CALLING FOR RAIN SHOWERS OVER MOST NEBRASKA ZONES GIVEN THE
LACK OF INSTABILITY FOR THUNDERSTORMS. WILL CONTINUE TO KEEP A
MENTION OF ISOLATED THUNDERSTORMS SOUTH OF A HEBRON TO ALMA LINE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM/AVIATION...WESELY
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1058 AM CDT WED SEP 12 2012
.DISCUSSION...
CHALLENGE WITH MORNING UPDATE CONCERNS FIRE WEATHER HEADLINES.
MODELS ARE IN GOOD AGREEMENT AND WILL USE A BLENDED SOLUTION.
15 UTC REGIONAL RADARS SHOW BAND OF RAIN SHOWERS FROM MITCHELL SD
TO ST CLOUD MN...COINCIDENT WITH 700 HPA MOISTURE GRADIENT AND
FRONTOGENESIS. THIS AREA OF PRECIPITATION WILL CONTINUE A SLOW
EASTWARD PROGRESSION AS UPPER LOW ACROSS NORTHERN MANITOBA MOVES
ACROSS HUDSON BAY. HIGH LEVEL CLOUDS ACROSS SOUTHEAST FORECAST
AREA WILL ALSO DISSIPATE AND MOVE EAST THROUGH THE DAY. FARTHER
NORTH...CLEAR SKIES WILL BE THE RULE GIVEN A VERY DRY BOUNDARY
LAYER AND CONVECTIVE TEMPERATURES IN THE 90S. TEMPERATURES STILL
ON TRACK TO REACH THE MID 60S TO NEAR 70 DEGREES. WITH DEW POINT
TEMPERATURES DROPPING INTO THE 20S...MINIMUM RH VALUES SHOULD BE
15 TO 20 PERCENT REGION-WIDE.
MODEL SOUNDINGS SUGGEST BOUNDARY LAYER WILL DEEPEN TO 700 HPA BY
MID-LATE AFTERNOON. LATEST RAP SHOWS A CORRIDOR OF 40 KTS AT 700
HPA FROM COOPERSTOWN TO DETROIT LAKES. ASSUMING EVENTUAL CLEARING
FROM WEST TO EAST AND EFFICIENT HEATING/MIXING...THINK WINDS WILL
INCREASE ABOVE 20 TO 25 MPH CRITICAL FIRE WEATHER THRESHOLD ALONG
AND NORTH OF THE INTERSTATE 94/HIGHWAY 10 CORRIDOR. WILL EXPAND
RED FLAG WARNING SOUTH TO INCLUDE THESE AREAS.
STRONG WEST-NORTHWEST WIND WILL APPROACH AND MAY BRIEFLY REACH
WIND ADVISORY THRESHOLDS (SUSTAINED 30 MPH) ACROSS PORTIONS OF
THE DEVILS LAKE BASIN THIS AFTERNOON...BUT WILL HOLD OFF ON
ADDITIONAL HEADLINES GIVEN SHORT DURATION AND MARGINAL WIND
SPEEDS.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE AS HIGH CIRRUS CLOUDS MOVE SLOWLY
OUT OF THE AREA. BIGGER CONCERN FOR THIS AFTERNOON WILL BE WINDS.
WEST WINDS WILL INCREASE DURING THE NEXT FEW HOURS INTO THE 15 TO
25 KT RANGE WITH GUSTS UP ABOVE 30 KTS AT TIMES. THE WINDS WILL
DECREASE AGAIN BELOW 12 KTS AFTER 00Z.
&&
.FIRE WEATHER...
WILL EXPAND RED FLAG WARNING FARTHER SOUTH WITH MORNING UPDATE AND
INCLUDE AREAS ALONG AND NORTH OF THE I-94/HWY 10 CORRIDOR. CRITICAL
FIRE WEATHER CONDITIONS EXPECTED ACROSS THE CENTRAL AND NORTHERN
FORECAST AREA. WEST-NORTHWEST WINDS EXPECTED TO BE ABOVE 20-25
MPH CRITERIA AND HUMIDITIES TO FALL UNDER 25 PERCENT THIS AFTERNOON.
MAY HAVE SOME GUSTS UP 35-40 MPH WITH MIXED LAYER TO 7-10 THOUSAND
FT. NEAR CRITICAL FIRE CONDITIONS WILL BE POSSIBLE OVER THE
REMAINDER OF THE FORECAST AREA WITH LOW HUMIDITIES EXPECTED ACROSS
MUCH OF THE FORECAST AREA.
&&
.PREV DISCUSSION... /ISSUED 352 AM CDT WED SEP 12 2012/
SHORT TERM...TODAY THROUGH FRIDAY NIGHT.
FAIR AMOUNT OF DIFFERENCES BETWEEN THE MODELS BY 84 HOURS. THE GFS
AND GEM WERE THE FAST SOLUTIONS WHILE THE THE NAM THE SLOWEST AND
THE ECMWF A COMPROMISE. WILL PREFER THE ECMWF.
UPPER LEVEL LOW PRESSURE SYSTEM WAS OVER NORTHERN MAN WITH TROUGH
EXTENDING INTO ND. WATER VAPOR LOOP INDICATED WOUND UP SYSTEM OVER
NORTHERN MAN. SECONDARY TROUGH WAS OVER WESTERN MT. SHORT WAVE
FORECAST TO STAY SOUTH AND WEST OF THE AREA. ALSO WATER VAPOR LOOP
INDICATED CIRCULATION CENTER OVER NW ALTA. ALTA SHORT WAVE FORECAST
TO MOVE ACROSS THE FORECAST AREA THU. NO PRECIPITATION IN THE
FORECAST FOR THU. CROSS SECTION INDICATED DRY LAYER UP TO 10
THOUSAND FT. SO WILL NOT ADD ANY POPS FOR NOW.
RADAR SHOWED SPRINKLES/VERY LIGHT SHOWERS OVER FAR SOUTHEAST ZONES
IN RIGHT REAR QUAD OF UPPER LEVEL JET. WILL ADD SPRINKLES IN THE
SOUTHEAST EARLY THIS MORNING.
PRECIPITABLE WATER REMAINS UNDER HALF AN INCH THROUGH 48 HOURS. THEN
A LITTLE ABOVE HALF AN INCH THEREAFTER.
AFTER THU...UPPER RIDGE OVER THE WESTERN US WILL MOVE OVER THE
NORTHERN PLAINS IN A PROGRESSIVE PATTERN.
SURFACE HIGH PRESSURE OVER SOUTHWEST CANADA WILL MOVE INTO THE
WESTERN DAKOTAS THU MORNING. WILL LOWER TEMPS FOR THU MORNING AND
FRI MORNING. HIGH TEMPS TWEAKED NEW COUPLE DAYS.
LONG TERM (SATURDAY-TUESDAY)...
00Z MODEL RUNS CONTINUE TO SHOW THE SAME IDEA AS PREVIOUS RUNS. THE
MAIN FEATURE OF THIS PERIOD WILL BE A COLD FRONT THAT DROPS THROUGH
THE REGION SATURDAY NIGHT OR SUNDAY. EXPECT ABOVE NORMAL
TEMPERATURES AHEAD OF THIS FEATURE...WITH BELOW NORMAL VALUES
BEHIND. AIRMASS REMAINS RELATIVELY DRY...BUT CANNOT RULE OUT
ISOLD/SCATTERED SHOWERS/THUNDER IN FRONTOGENETIC ZONE JUST BEHIND
THE FROPA.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR NDZ006>008-
014>016-024-026>030-038-039-054.
MN...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ001>009-
013>017-022>024-027-028.
&&
$$
ROGERS/HOPPES/JR
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1018 AM CDT WED SEP 12 2012
.UPDATE...
SEE MORNING UPDATE.
.DISCUSSION...
13Z SURFACE MAPS SHOWS WEAK CONVERGENCE ALONG THE COAST AND
SCATTERED SHRA/TSRA INCREASING IN COVERAGE OVER THE COASTAL
COUNTIES. 850 MB MOISTURE LOOKS RATHER PLENTIFUL OVER THE EASTERN
HALF OF THE STATE. 700 MB MOISTURE ALSO LOOKS RATHER DEEP FROM
CRP TO LCH. 4 KM WRF AND NMM DON`T SHOW MUCH PRECIP COVERAGE TODAY
WHILE THE LATEST RAP 13 SHOWS GOOD PCPN COVERAGE. 12Z SOUNDINGS
SHOW LOW CONVECTIVE TEMPS...BETWEEN 85 AND 87 DEGREES WITH PW
VALUES BETWEEN 1.8 AND 1.9 INCHES. WEAK CAPPING IS NOTED NEAR 600
MB. WILL LEAN TOWARD THE MORE AGGRESSIVE RAP SINCE THE 12Z
SOUNDINGS LOOK TO BE SUPPORTIVE OF HIGHER RAIN CHANCES. TEMPS LOOK
TO BE ON TRACK ALTHO INCREASED CLOUDS AND RAIN MAY KEEP MAX TEMPS
A LITTLE COOLER. NEW ZONES OUT BY 1030 AM. 43
&&
.PREV DISCUSSION... /ISSUED 452 AM CDT WED SEP 12 2012/
DISCUSSION...
STRONG WAA/MOISTURE RETURN HAS BROUGHT SCT SHRA TO THE SRN HALF OF
SE TX LAST NIGHT. THIS PATTERN EXPECTED TO REMAIN IN PLACE FOR THE
NEXT FEW DAYS WITH GULF MOISTURE DEEPENING THROUGHOUT. THIS SHOULD
HELP TO INCREASE POPS BY THE END OF THE WEEK ACROSS OUR FA. ALL OF
THIS SEEMS TO BE A PRELUDE TO A RATHER WET WEEKEND AS A COLD FRONT
AND AN ASSOCIATED COASTAL SFC LOW IN/ACROSS THE REGION. THIS FRONT
FCST TO STALL AT/NEAR THE COAST SAT WITH A LOW PROGGED TO DEVELOP/
FORM ALONG THE BOUNDARY AND MOVE UP THE COAST ON SUN. MODELS ARE A
BIT HINKY WITH THE TIMING OF CLEARING...SO HAVE OPTED TO GO SLOWER
(KEEPING POPS IN THE FCST THRU MON). THE MAIN UNCERTAINTY SEEMS TO
BE HOW WE ARE GOING TO GET PCPN RATHER THAN IF WE ARE GOING TO GET
PCPN. (I.E. ALL SIGNS POINT TO A WET WEEKEND.) 41
MARINE...
WARM FRONT OVER THE COASTAL AREAS EARLY THIS MORNING LIFTING NORTH
TODAY WILL DEEPEN THE MOISTURE ACROSS THE UPPER TEXAS COASTAL
WATERS LEADING TO SCATTERED SHOWERS AND THUNDERSTORMS. CAPE OF
2000-3500 J/KG THIS MORNING WITH A SLIGHTLY BACKED LL FLOW COULD
POSE A THREAT OF TROPICAL FUNNEL CLOUDS ESPECIALLY IN THE AREAS TO
THE EAST OF FREEPORT THROUGH HIGH ISLAND. EASTERLY FLOW DEVELOPING
TONIGHT AND THURSDAY AS HIGH PRESSURE TO THE NORTHEAST STEERS FLOW
WITH A COLD FRONT SLIPPING SOUTH ACROSS THE RED RIVER AND INTO THE
UPPER TEXAS NEARSHORE WATERS SATURDAY AFTERNOON OR SUNDAY
MORNING. GFS/ECMWF DIFFER DRAMATICALLY BY MONDAY AND FAVORING THE
ECMWF SOLUTION WITH A STATIONARY FRONTAL BOUNDARY WITH FRONTAL WAVES
IN THE COASTAL WATERS.
45
AVIATION...
SHORT TERM EXPECT THAT SHOWERS WILL CONTINUE TO DEVELOP IN THE
LEADING EDGE OF THE DEEPER MOISTURE ALONG THE WARM FRONT THIS
MORNING OVER THE HOU-GLS TERMINALS THEN SPREAD INLAND LATE MORNING
AND BEYOND. SOME PATCHY MVFR CIGS POSSIBLE THIS MORNING THOUGH
PRIMARILY ASSOCIATED WITH THE PASSING SHOWERS. VCSH SHOULD COVER IT
FOR NOW WITH TEMPO SHRA CONDITIONS AT LBX/GLS/SGR/HOU BETWEEN 10-
14Z GIVEN THE CURRENT TRENDS ON RADAR. SHOWERS AND THUNDERSTORMS
PROBABILITY INCREASING MID TO LATE MORNING NEAR IAH AND THEN THROUGH
THE AFTERNOON. EASTERLY FLOW THIS MORNING BECOMING SSE AS MOIST FLOW
DEEPENS THEN BACKS OVERNIGHT WITH SCATTERED SHRA/ISO TSRA AGAIN
THURSDAY MORNING.
45
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 92 74 91 72 88 / 30 20 40 50 50
HOUSTON (IAH) 90 74 90 72 88 / 40 30 40 40 50
GALVESTON (GLS) 88 79 88 78 87 / 40 30 40 40 50
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...43
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
630 AM CDT WED SEP 12 2012
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
339 AM CDT WED SEP 12 2012
MAIN FORECAST CONCERNS ARE PRECIPITATION AND TEMPERATURE TRENDS
THROUGH THURSDAY...THEN POTENTIAL FOR VALLEY FOG AND PATCHY FROST
THURSDAY NIGHT INTO FRIDAY MORNING.
AS OF 08Z WEDNESDAY...WATER VAPOR IMAGERY AND RAP 500MB HEIGHT
FIELDS DEPICT A LARGE TROUGH ACROSS SOUTHERN CANADA INTO THE
NORTHERN PLAINS WHILE A LARGE RIDGE OF HIGH PRESSURE WAS CENTERED
ACROSS THE SOUTHEAST US. IN-BETWEEN...A PLUME OF SOUTHWEST MONSOONAL
MOISTURE WAS BEING ADVECTED NORTHEAST TOWARDS THE FORECAST AREA
WHERE PRECIPITABLE WATER VALUES RANGED FROM 0.75 TO 1.1 INCHES / 80
TO 120 PERCENT OF NORMAL / PER GOES SOUNDER IMAGERY. A 250MB JET
STREAK WAS NOTED ACROSS NORTHERN NORTH DAKOTA INTO EXTREME SOUTHWEST
ONTARIO. AT THE SURFACE...A COLD FRONT STRETCHED FROM NORTHWEST
WISCONSIN TO THE TWIN CITIES TO OMAHA NEBRASKA WHERE COMBINED WITH
INCREASING 850 MB TRANSPORT AHEAD OF THE FRONT AND MID TO UPPER
LEVEL FRONTOGENETICAL SUPPORT WAS GENERATING POST FRONTAL SHOWERS.
MEANWHILE...SOME WARM AIR ADVECTION SHOWERS AHEAD AND ALONG THE
FRONT WERE DEVELOPING ACROSS NORTHERN IOWA INTO SOUTHERN MINNESOTA.
DEWPOINT DEPRESSIONS REMAINED 25 TO 30F BUT A FEW SITES WERE
REPORTING PRECIPITATION UNDER 8 TO 10 KFT CLOUD BASES. LATEST IR
IMAGERY SHOWS HIGH CLOUDS ACROSS MUCH OF THE FORECAST AREA.
TODAY AND TONIGHT...EXCELLENT AGREEMENT BETWEEN THE LATEST
NAM/GFS/ECMWF/SREF/RAP DEPICTING THE COLD FRONT MAKING A STEADY
PROGRESS SOUTHEAST THROUGH THE FORECAST AREA SUCH THAT BY 12Z IT
SHOULD BE ALONG A BLACK RIVER FALLS TO LA CROSSE WISCONSIN TO
CHARLES CITY IOWA LINE. TEMPERATURES ARE TRICKY WITH CONTINUED
SOUTHWEST FLOW EXPECTED AHEAD OF THE FRONT WHERE LOCATIONS IN
NORTHEAST IOWA AND EXTREME SOUTHWEST WISCONSIN SHOULD REMAIN IN WARM
SECTOR FOR MUCH OF THE DAY...TOPPING OUT IN THE LOWER TO MIDDLE
80S. NON-DIURNAL TREND ON TRACK FOR OTHER SPOTS WHERE HIGHS SHOULD
OCCUR AROUND 18Z...FALLING INTO THE MIDDLE 60S BY 21Z. AS DEWPOINTS
CRASH INTO THE UPPER 40S LATE THIS AFTERNOON AND PRECIPITATION
BEGINS...TEMPERATURES LOOK TO QUICKLY DROP OFF.
DYNAMICS LOOK GOOD WITH FORECAST AREA FAVORABLY POSITIONED IN THE
RIGHT ENTRANCE REGION OF THE 250MB JET. A NW-SE CROSS SECTION
THROUGH THE REGION SHOWS STRONG FRONTOGENETICAL BAND WITH IDEAL
FRONTOLYSIS/FRONTOGENETICAL CIRCULATION SETTING UP ACROSS THE AREA
BEGINNING THIS EVENING. STRONG ISENTROPIC UPGLIDE ON THE 305-315K
SURFACES IS PRESENT ALONG WITH DECENT 850 MB MOISTURE TRANSPORT.
DESPITE SOME LOW LEVEL DRY AIR CONCERNS INITIALLY...THAT SHOULD BE
OVERCOME SUCH THAT SHOWERS WILL DEVELOP / MOVE INTO SOUTHEAST
MINNESOTA AND WESTERN WISCONSIN BETWEEN 22-00Z...THEN SAG SOUTHEAST
THROUGH THE NIGHT. THE LATEST MESO MODELS ARE IN GOOD AGREEMENT WITH
THIS SCENARIO AS WELL. REGARDING RAINFALL TOTALS THROUGH THE
EVENT...A NORTH/SOUTH GRADIENT SHOULD SET UP AS BETTER FORCING/LIFT
ACROSS IOWA INTO SOUTHERN WISCONSIN. TOTALS AROUND 1/10 OF AN INCH
ACROSS NORTH CENTRAL WISCONSIN....TO 1/3 TO 1/2 ALONG THE I-90
CORRIDOR...THE UPWARDS OF 3/4 OF AN INCH LOOK PROMISING FOR THE
AREA.
THURSDAY AND FRIDAY...BY 12Z THURSDAY...THE BULK OF THE
PRECIPITATION SHOULD BE ORIENTED THROUGH CENTRAL WISCONSIN TO
NORTHEAST IOWA. TIMING THE PROGRESS OF THIS PRECIPITATION OUT OF THE
FORECAST AREA IS A BIT TRICKY. THIS IS MOST LIKELY DUE TO MODEL
TIMING DIFFERENCES INCREASING ON HOW THE NEXT SHORTWAVE...CURRENTLY
IN NORTHWEST ALBERTA...DIVING SOUTHEAST DURING THE DAY THURSDAY IS
HANDLED. THE 12.00Z NAM IS A SLOWER OUTLIER...WHILE THE 12.00Z
GFS/CANADIAN/ECMWF ARE IN GOOD AGREEMENT. HAVE DISCOUNTED THE NAM
FOR THE TIME BEING...GIVEN TRENDS OVER THE PAST DAY TO BE FASTER.
THE HIGHEST PRECIPITATION CHANCES AFTER 15Z THURSDAY LOOK TO BE
SOUTH/EAST OF A SPARTA WISCONSIN TO OELWEIN IOWA LINE. A COOL DAY ON
TAP FOR THE AREA WITH MOSTLY CLOUDY TO CLOUDY SKIES UNDER COLD AIR
ADVECTION AND 850MB TEMPS PROGGED TO BE 5-8C. AREAS SOUTH/EAST WILL
BE THE COOLEST WITH MORE CLOUDS/RAIN...AND PROBABLY WILL ONLY MAKE
IT TO 60F AT BEST. AS THE NORTHWEST ALBERTA SHORTWAVE DIVES THROUGH
MINNESOTA DURING THE AFTERNOON AND COMBINES WITH DIURNAL
HEATING...SCATTERED SHOWERS ARE POSSIBLE...MAINLY CONFINED TO THE
NORTHWEST AREAS. STEEPER LAPSE RATES AND MAYBE SOME INSTABILITY TO
WORK WITH COULD PRODUCE A RUMBLE OR TWO OF THUNDER AS WELL.
THE NORTHWEST ALBERTA SHORTWAVE QUICKLY PIVOTS THROUGH THE NORTHERN
PLAINS LATE THURSDAY AND BY 06Z FRIDAY SHOULD BE CENTERED ACROSS
WISCONSIN. AT THE SURFACE...BUILDING CANADIAN HIGH PRESSURE THURSDAY
NIGHT INTO FRIDAY MORNING WILL BRING SOME OF THE COLDEST AIR OF THE
AUTUMN SEASON THUS FAR. THE COMBINATION OF PRECIPITABLE WATER VALUES
DROPPING TO A 0.5 INCH OR LESS...DIMINISHING WINDS WITH THE HIGH
PRESSURE AREA BUILDING IN AND CLEARING SKIES WILL ALL HELP
TEMPERATURES TO TANK. LOWS LOOK TO DROP DOWN TO THE LOWER 40S TO
AROUND 40 FOR MOST LOCATIONS. ALONG AND NORTHEAST OF THE I-94
CORRIDOR IN WISCONSIN...THE TYPICAL COLD SPOTS COULD EVEN SEE SOME
PATCHY FROST...THOUGH THIS WOULD ALL HINGE ON THE SURFACE HIGH
POSITION. RIVER VALLEY FOG WOULD ALSO BE A CONCERN GIVEN THIS
SYNOPTIC SETUP...ESPECIALLY GIVEN EXPECTED RAINFALL OVER THE NEXT 36
HOURS AND THE COOLER AND CLOUDIER DAY EXPECTED THURSDAY. RIGHT NOW
THE GFS IS A FASTER OUTLIER IN BRINGING IN THE SURFACE HIGH...MAKING
ITS SOLUTION THE MOST FAVORABLE FOR WIDESPREAD VALLEY FOG AND ALSO
MORNING FROST ACROSS NORTH CENTRAL WISCONSIN. DEFINITELY SOMETHING
TO WATCH CLOSELY IN THE NEXT FORECAST RUNS. FOR NOW HAVE ONLY
INCLUDED AREAS OF FOG FOR THE WISCONSIN RIVER AND ITS TRIBUTARIES...
AND PATCHY FOG FOR THE MISSISSIPPI RIVER. FRIDAY LOOKS TO BE A VERY
PLEASANT DAY FOR THE ENTIRE UPPER MIDWEST WITH THE HIGH PRESSURE
DRIFTING OVERHEAD...PROVIDING LIGHT WINDS. 850MB TEMPS OF 6-8C AND
PLENTY OF SUN SHOULD RESULT IN HIGHS SLIGHTLY BELOW NORMAL...IN THE
UPPER 60S TO LOWER 70S.
QUIET WEATHER LOOKS TO PERSIST INTO FRIDAY NIGHT WITH THE HIGH
PRESSURE REMAINING NEARBY. LOW PRECIPITABLE WATER VALUES ARE STILL
SUGGESTED...SO ANOTHER COOL NIGHT IS EXPECTED WITH LOWS IN THE UPPER
30S AT THE TYPICAL COLD SPOTS AND LOW TO MID 40S ELSEWHERE. MAY
AGAIN BE DEALING WITH VALLEY FOG AND FROST.
.LONG TERM...SATURDAY THROUGH TUESDAY NIGHT
339 AM CDT WED SEP 12 2012
12.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES ARE IN MUCH BETTER
AGREEMENT ON THE UPPER LEVEL PATTERN COMPARED TO THE PAST FEW DAYS
FOR THE LONG TERM FORECAST. THERE STILL ARE SOME ISSUES...MOSTLY
IMPACTING TUESDAY AND TUESDAY NIGHT.
TO BEGIN THE LONG TERM FORECAST...NEARLY ZONAL FLOW EXISTS WITH THE
WESTERLIES RUNNING ACROSS SOUTHERN CANADA. WITHIN THIS FLOW...
THOUGH...THERE IS A POTENT SHORTWAVE CROSSING NORTHERN SASKATCHEWAN
WITH INDICATIONS OF TROUGHING BEGINNING TO FORM OVER WESTERN
ALBERTA. THIS TROUGHING ENDS UP DEEPENING ACROSS CENTRAL CANADA BY
LATE SUNDAY DUE TO RIDGING BUILDING UP INTO BRITISH COLUMBIA. AHEAD
OF THIS UPPER TROUGHING AND ASSOCIATED WITH THAT POTENT SHORTWAVE...
MODELS DEPICT A COLD FRONT. THIS FRONT LOOKS TO CROSS THE FORECAST
AREA SUNDAY NIGHT AT THE PRESENT TIME...WHICH IS WHEN THE TROUGHING
BEGINS TO DIG DOWN INTO THE NORTH CENTRAL U.S.. ANTICIPATING DRY
WEATHER UNTIL THIS FRONT PASSES...DUE TO THE DRY AIRMASS AHEAD OF
IT. WITH 850MB TEMPS RUNNING AROUND 8C ON SATURDAY AND 10-12C ON
SUNDAY...HIGH TEMPERATURES BOTH DAYS SHOULD BE ABLE TO TOP OUT IN
THE 70S. CHANGES ARE DEFINITELY ON THE WAY FOR MONDAY...THOUGH...AS
THE UPPER TROUGH APPROACHES THE AREA. LIKE TODAY THROUGH THURSDAY...
INDICATIONS ARE THAT A FRONTOGENETIC BAND OF PRECIPITATION WILL FORM
BEHIND THE COLD FRONT. HOW MUCH PRECIPITATION FORMS DEPENDS ON HOW
MUCH THE UPPER TROUGHING DIGS DOWN INTO THE NORTH CENTRAL U.S....
WHICH IS A LITTLE UNCERTAIN AT THIS TIME. THEREFORE...WILL BE
FOLLOWING THE CONSENSUS PRECIPITATION CHANCES OF 30-40 FOR MONDAY
AND MONDAY NIGHT. IF MODEL TRENDS CONTINUE...CHANCES ARE LIKELY
GOING TO BE RAISED IN LATER FORECASTS FOR MONDAY AND MONDAY NIGHT.
THE FORECAST FOR TUESDAY AND TUESDAY NIGHT ALSO RELY ON WHAT HAPPENS
WITH THE NORTH CENTRAL U.S. TROUGH. THE 12.00Z GFS FORMS A CLOSED
UPPER LOW OVER THE FORECAST AREA WHILE THE 11.12Z/12.00Z ECMWF KEEP
THE TROUGH PROGRESSIVE. THE FORMER SCENARIO YIELDS WET WHILE THE
LATTER SCENARIO SUGGESTS DRY...THOUGH BOTH ARE COOL AS 850MB TEMPS
TUMBLE TO A CHILLY 0-2C. 12.00Z GFS ENSEMBLES SUGGESTS BOTH THE GFS
AND ECMWF ARE POSSIBLE...THEREFORE 20-30 PERCENT CHANCES OF
PRECIPITATION ARE IN THE FORECAST. HIGHS TUESDAY WILL BE AT LEAST 15
DEGREES COLDER THAN THOSE ON SUNDAY...IF NOT MORE.
&&
.AVIATION...THROUGH 12Z THURSDAY
630 AM CDT WED SEP 12 2012
A COLD FRONT WILL CONTINUE TO MOVE SOUTHEAST ACROSS THE AREA THIS
MORNING. THE FRONT PASSED KRST AROUND 11Z AND SHOULD PASS KLSE BY
15Z. FORCING/LIFT AND MOISTURE TRANSPORT OVER THIS FRONT WAS
PRODUCING A BROAD BAND OF -RA/-SHRA FROM EASTERN NEB TO FAR
NORTHWEST WI. CIGS/VSBYS IN THE PRECIP EARLY THIS MORNING WERE
GENERALLY 8-10K FT AND 10SM. WITH THE FRONT MOVING SLOWLY ACROSS THE
AREA TODAY...A PROLONGED PERIOD OF THE POST-FRONTAL FORCING/LIFT AND
MOISTURE TRANSPORT IS EXPECTED OVER THE TAF SITES. THIS LEADS TO
LONGER PERIODS OF VCSH OR -SHRA IN THE TAFS...BUT CONDITIONS LOOK TO
REMAIN MOSTLY VFR AS THE MAIN FORCING/LIFT IS ABOVE 850MB AND THE
SFC-850MB FLOW BEHIND THE FRONT IS DRIER AND FROM THE NORTH. DID ADD
A PERIOD OF 6SM -SHRA TO BOTH KRST/KLSE LATER THIS AFTERNOON/
EVENING...WHEN THE STRONGEST/DEEPEST OF THE FORCING/LIFT IS EXPECTED
TO TRANSLATE ACROSS THE TAF SITES AND PRODUCE A PERIOD OF MODERATE
RA/SHRA. CONDITIONS IMPROVE TO GOOD VFR LATER TONIGHT AS THE BAND OF
-SHRA/-RA SINKS SOUTH OF THE AREA AND DEEPER/DRIER AIR IN THE
SFC-700MB LAYER SPREADS INTO THE AREA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
339 AM CDT WED SEP 12 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....AJ
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
335 PM EDT Wed Sep 12 2012
.NEAR TERM [Tonight]...
Isolated to scattered showers were maintained in the forecast, and
should affect mainly the Gulf of Mexico waters, as well as immediate
coastal locations and the eastern Florida Big Bend. Convection thus
far near the Suwannee River has been quite shallow with no lightning
noted. The HRRR continues this trend overnight, but some thunder was
included for offshore areas of the coastal waters. We should see a
mix of mid-high level cloud cover again tonight which should keep
low temperatures in the mid-60s in most non-coastal areas, and close
to 70 around the coast.
&&
.SHORT TERM [Thursday Through Friday]...
The mid level ridge over the Eastern CONUS will continue to break
down through the remainder of the week as a trough builds toward the
Mid Atlantic by Friday. Our region will remain in a steady easterly
flow regime with gradually increasing moisture levels each day. The
absence of any large scale support (the main energy with the trough
will stay well to the north), rain chances will be on the low side.
Confidence in this forecast is bolstered by the NAM coming more
inline with the GFS with respect to its pop forecast favoring lower
end chances through the end of the week.
&&
.LONG TERM [Friday Night through Tuesday]...
The large scale longwave pattern commences in Nrn stream with a weak
trough along West Coast, broad ridge Ewd to Appalachians and low
over QUE with trough axis SWD along Atlc Coast. SRN stream marked by
high over Srn CA/Baja, trough over Srn Plains and weak ridging Ewd
to FL as high again anchors to our N. At surface, low over Great
Lakes with cold front SWD thru Ern TN Valley then SW thru SE TX.
This places local area in weak warm sector with onshore flow and
weakening gradients ending ELY surges.
The latest run of the 00z GFS and EURO coming into better agreement
showing an increasingly amplifying/digging trough moving from Plains
Ewd to dominate Gulf region by Mon. Deepening trough drags cold
front SEWD to bisect our area by Mon eve. At same time, a shortwave
over the Plains to commence the period gets swept into longwave
trough and moves NEWD enhancing local rainfall by Sat. Also it
likely develops surface reflection in W/Cntrl Gulf Coast by Sat
night that lifts along front across local area late Sun into Mon
then out of our area by late Tues. This solution would favor a
relatively wet and windy period especially Sun eve thru Tues.
Will go with wdly sct-lo sct POPs Fri night, Sct pops Sat thru Tues
with highest pops on Mon. With area being in warm sector and under
ample clouds, min temps with with several degrees above climo. Max
temps will hover around climo. Avg inland climo is 66/87 degrees.
&&
.AVIATION [Through 18z Thursday]...
VFR expected through the TAF period. A few very brief or isolated
-SHRA possible at VLD through late afternoon, so VCSH was added to
the TAF. One couldn`t be ruled out at TLH, but confidence is lower
there, so none were mentioned in the 18z set of TAFs.
&&
.MARINE...
Our coastal waters will reside on the southern edge of the
high pressure for the next several days. The increased
pressure difference between the edge of the ridge, and the weaker
pressure pattern in the Gulf will create elevated winds through at
least Thursday. Additionally, the easterly wind will yield
nocturnal surges that spread from east to west each night through
the remainder of the week.
&&
.FIRE WEATHER...
The trend in low-level moisture should be for a gradual increase
through the weekend and early next week. Red flag conditions are not
expected.
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...None.
GA...None.
FL...None.
GM...Small Craft Advisory from 8 PM this evening to 11 AM EDT
Thursday from Apalachicola to Suwannee River out to 60 nautical
miles.
Small Craft Advisory from 2 AM to 2 PM EDT Thursday from
Apalachicola to Destin out to 60 nautical miles.
&&
$$
NEAR TERM...Lamers
SHORT TERM...Godsey
LONG TERM...Block
AVIATION...Lamers
MARINE...Harrigan/Godsey
FIRE WEATHER...Lamers
AREA FORECAST DISCUSSION
NWS MIAMI FL
156 PM EDT WED SEP 12 2012
.AVIATION...
AS THE EARLY AFTERNOON PROGRESSES IT LOOKS LIKE CONVECTION MAY NOT
BECOME ORGANIZED ALONG THE EASTERN ATLANTIC COASTAL ZONE WITH EAST COAST
TAF SITES KFXE...KFLL AND KMIA ASSIGNED VCSH AT 18Z AND THE MORE
INLAND SITES KTMB AND KOPF ASSIGNED VCTS IF CONVECTION BECOMES
ORGANIZED INLAND BUT CONFIDENCE IS LOW. THE TERMINAL MOST LIKELY
TO EXPERIENCE CONVECTION WILL BE TERMINAL KAPF WITH VCTS ASSIGNED
AT 19Z...WITH THE MODERATE EASTERLY FLOW THE WESTERN PORTIONS OF
THE PENINSULA WILL BE THE AREA MOST FAVORED FOR AFTERNOON
CONVECTION. WITH OCCURRENCE OF SHOWERS OR A THUNDERSTORMS BRIEF
PERIODS OF SUB-VFR CONDITIONS MAY BE EXPERIENCED.
60
&&
.PREV DISCUSSION... /ISSUED 1013 AM EDT WED SEP 12 2012/
UPDATE...
THE 12Z SOUNDING THIS MORNING SHOWED DRIER AND WARMER AIR IN THE
LOW TO MID LEVELS...WITH MODERATE EAST TO NORTHEAST FLOW UP TO
700MB. THERE WAS A WEAK BOUNDARY LOCATED ACROSS THE FLORIDA
STRAITS...AND THE HIGHER MOISTURE AND CONVERGENCE WILL BE LOCATED
SOUTH OF THE REGION TODAY. THE HRRR SHOWS THIS AS WELL...WITH
MOSTLY ISOLATED TO SCATTERED SHOWERS AS THERE WILL BE A LACK OF
FOCUS FOR STORMS. A NORTHEAST FLOW USUALLY DOES NOT FAVOR MUCH
ACTIVITY ALONG MOST OF THE EAST COAST ANYWAY...BUT WILL LEAVE THE
HIGHER POPS FOR THE SOUTHEAST COAST AS THAT REGION IS CLOSER TO
THE BOUNDARY. LOWERED POPS ACROSS THE WEST BACK TO SCATTERED AND
REDUCED TO ISOLATED THUNDERSTORMS ACROSS THE WEST AS WELL...AS THE
FLOW SHOULD BE TOO STRONG TO GET A GULF COAST SEA BREEZE.
OTHERWISE...BREEZY CONDITIONS WITH PARTLY CLOUDY TO MOSTLY CLOUDY
SKIES SHOULD PREVAIL ACROSS THE REGION...WITH HIGHS IN THE UPPER
80S TO LOWER 90S.
PREV DISCUSSION... /ISSUED 726 AM EDT WED SEP 12 2012/
AVIATION...
A STALLED FRONT OVER EXTREME S FLA/THE UPPER FLA STRAITS
WILL DISSIPATE TODAY. A STRONG RIDGE OF HIGH PRESSURE OFF OF THE NEW
ENGLAND COAST OVER THE ATLC AND EXTENDING SW INTO THE SE U.S. WILL
PERSIST THROUGH THE PERIOD. A FEW FAST MOVING SHRA MOVING OVER THE
ATLC WILL MOVE ONSHORE BUT AT THIS TIME NO VCSH IN E COAST TAFS. AFT
16Z VCTS E COAST TERMINALS BUT POSSIBLE THAT THE TSRA WILL BE W OF
TERMINALS. SURFACE WINDS CURRENTLY NE-ENE UP TO 10 KNOTS WITH GUSTS
TO MID/UPPER TEENS POSSIBLE. AFT 14Z WINDS INCREASE TO 12 TO 15
KNOTS WITH GUSTS > 20 KNOTS. AT KAPF...VFR THROUGH 16Z WITH NO
WEATHER THEN VCSH POSSIBLE UNTIL 18Z THEN VCTS. TSTMS MAY PRODUCE
FREQUENT MVFR CIG/VSBY. SURFACE WIND CURRENTLY NE < 10 KNOTS
BECOMING NE-ENE 10 TO 12 KNOTS WITH GUSTS AROUND 20 KNOTS AFT 15Z.
60
PREV DISCUSSION... /ISSUED 307 AM EDT WED SEP 12 2012/
SHORT TERM (TODAY-FRIDAY)...
A STALLED FRONTAL BOUNDARY COMBINED WITH PLENTY OF DEEP LAYER
MOISTURE WILL KEEP THE RAIN CHANCES IN THE FORECAST THROUGH THE
MID-WEEK PERIOD. EARLIER THIS MORNING...SCATTERED MODERATE TO
HEAVY SHOWERS DUE TO AN EASTERLY WIND SURGE NORTH OF THE FRONTAL
BOUNDARY IMPACTED PORTIONS OF THE LOCAL AREA...ESPECIALLY ALONG
THE EAST COAST FROM DELRAY BEACH TO LAKE WORTH WHERE ACCUMULATIONS
REACHED THE THREE QUARTER TO ONE INCH MARK WITHIN A ONE TO THREE
HOUR PERIOD. THE LATEST MODEL GUIDANCE REMAINS IN DECENT AGREEMENT
THROUGH THE UPCOMING 72 HOURS AND CONTINUES TO INDICATE THE
POTENTIAL FOR SCATTERED SHOWERS WITHIN THE MOIST EASTERLY FLOW TO
CONTINUE. MODEL PRECIPITABLE WATER VALUES ARE FORECAST TO REMAIN
AROUND THE 2 INCH MARK THROUGH THURSDAY...THEN STEADILY DECREASE
FROM NORTH TO SOUTH THURSDAY NIGHT THROUGH FRIDAY AS THE FRONTAL
BOUNDARY GRADUALLY SHIFTS SOUTH OF THE AREA AND FURTHER WEAKENS OR
DIMINISHES. AS A RESULT...WILL REFLECT THIS DECREASING RAINFALL
TREND THROUGH THE LATTER HALF OF THE SHORT-TERM PERIOD. FOR
TODAY...ALTHOUGH THE MODERATE EASTERLY FLOW WILL HELP SPREAD THE
AFTERNOON SHOWERS/TSTMS INLAND AND TOWARD THE SOUTHWEST FLORIDA
COAST...ANY ACTIVITY THAT BECOMES CONCENTRATED OVER PORTIONS OF
THE EAST COAST AND METRO AREAS ON TOP OF YESTERDAY`S RAINFALL
COULD LEAD TO MINOR FLOODING CONCERNS ONCE AGAIN.
LONG TERM (FRIDAY NIGHT-TUESDAY)...
OVER THE WEEKEND...THE MODERATE EASTERLY FLOW CURRENTLY IN PLACE
IS FORECAST TO RELAX AS THE FRONTAL BOUNDARY PREVIOUSLY DISCUSSED
DIMINISHES SOUTH OF THE AREA. THIS WILL ALLOW CONDITIONS TO RETURN
TO NORMAL FOR THIS TIME OF YEAR WITH MAINLY AFTERNOON
SHOWERS/TSTMS SETTING UP INLAND AND WEST EACH DAY. EARLY NEXT
WEEK...THE LATEST MODEL GUIDANCE INDICATES ANOTHER FRONTAL
BOUNDARY ASSOCIATED WITH A STRONG SHORTWAVE TROUGH TRANSLATING
EASTWARD ACROSS THE REGION. ALTHOUGH THE BULK OF THE DYNAMICS AND
FORCING WILL REMAIN WELL NORTH OF OUR LOCAL AREA...MOIST SOUTHERLY
FLOW WELL AHEAD OF THIS APPROACHING BOUNDARY MAY LEAD TO ABOVE
AVERAGE RAINFALL CHANCES MONDAY THROUGH TUESDAY...ESPECIALLY OVER
THE NORTHERN HALF OF THE LOCAL AREA AROUND THE LAKE REGION.
MARINE...
MODERATE EASTERLY WINDS AND SEAS WILL PERSIST THROUGH THE
MID-WEEK PERIOD...THEN STEADILY TREND BACK TOWARD NORMAL OVER THE
WEEKEND. AS A RESULT...SMALL CRAFT OPERATORS ARE ENCOURAGED TO
EXERCISE CAUTION OUT ACROSS THE LOCAL WATERS TODAY THROUGH THURSDAY.
IN ADDITION TO THE ABOVE AVERAGE WINDS AND SEAS...SCATTERED SHOWERS
AND STORMS CAN LEAD TO LOCALLY HIGHER WINDS AND SEAS ALONG WITH
REDUCED VISIBILITIES.
FIRE WEATHER...
A STALLED FRONT OVER EXTREME SOUTH FLORIDA AND THE UPPER FLORIDA
STRAITS WILL DISSIPATE TODAY. A STRONG RIDGE OF HIGH PRESSURE
EXTENDING FROM THE ATLANTIC OFF OF THE NEW ENGLAND COAST
SOUTHWEST TO OVER THE SOUTHEAST U.S....WILL PERSIST TODAY THROUGH
THURSDAY. THIS WILL PROVIDE A BRISK NORTHEASTERLY WIND FLOW OVER
SOUTH FLORIDA TODAY THROUGH THURSDAY.
SOME SHOWERS CAN BE EXPECTED THIS MORNING ALONG THE EAST COAST AND
AGAIN OVERNIGHT TONIGHT. BUT BY LATE MORNING TODAY AND AGAIN ON
THURSDAY...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED MAINLY IN THE INTERIOR AND WEST ZONES.
DISPERSION WILL BE GENERALLY GOOD MOST ZONES TODAY AND THURSDAY WITH
VERY GOOD DISPERSION TODAY WEST OF LAKE OKEECHOBEE.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 78 87 77 89 / 30 40 40 40
FORT LAUDERDALE 78 87 78 87 / 30 40 40 40
MIAMI 76 88 78 85 / 40 40 40 40
NAPLES 74 89 75 90 / 20 40 30 50
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1154 AM MDT WED SEP 12 2012
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 403 AM MDT WED SEP 12 2012
FORECAST PROBLEMS WILL BE PRECIPITATION TIMING/COVERAGE INTO
TOMORROW...HOW COOL TO MAKE HIGH TEMPERATURES THROUGH THURSDAY...
AND HOW COOL TO MAKE THE MINS THE NEXT THREE NIGHTS. SATELLITE
CONTINUING TO SHOW AN AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO
THE ATLANTIC. COMPLEX AND MODERATELY STRONG SHORTWAVE TROUGH MOVING
TOWARD THE AREA FROM THE SOUTHWEST. MID LEVEL MOISTURE HAS
INCREASED SIGNIFICANTLY FROM YESTERDAY WITH LOW LEVEL MOISTURE NOT
VERY PLENTIFUL. COLD FRONT IS CURRENTLY PLOWING THROUGH THE AREA.
AT JET LEVEL...THE NAM/CANADIAN WERE DOING SLIGHTLY BETTER THAN THE
ECMWF AND UKMET. THE GFS WAS A LITTLE TOO FAR EAST WITH THE UPPER
JET THAT WILL BE A MAIN PLAYER IN THE LIFT. AT MID LEVELS...MODELS
WERE HAVING TROUBLE CATCHING THE IMPORTANT DETAILS AND OVERALL
POSITION/STRENGTH OF THE INCOMING TROUGH. IN GENERAL THEY WERE TOO
DEEP AND/OR TOO FAST WITH THE TROUGH OVER THE SOUTHWEST PORTION OF
THE COUNTRY WITH THE NAM THE WORST OFFENDER. SATELLITE AND UPPER AIR
ANALYSIS WOULD SAY THE UKMET IS THE BEST RIGHT NOW. RUC WAS DOING
BEST WITH THE SHORT TERM FRONTAL POSITION AND WINDS FOLLOWED BY THE
NAM/CANADIAN. THE MODELS TENDED TO BE A LITTLE SLOW WITH THE FRONT.
THE GFS AND CANADIAN SEEM TO HAVE A DECENT HANDLE ON THE LOW LEVEL
THERMAL FIELD.
TODAY/TONIGHT...JET LIFT IS SLOWER TO ARRIVE THAN WHAT WAS SHOWN
YESTERDAY. BY 00Z IT LOOKS LIKE IT IS CLOSE TO OR OVER THE
NORTHWEST CORNER OF THE FORECAST AREA. THE JET LIFT REALLY DOES NOT
GET STRONG UNTIL BETWEEN 00Z TO 06Z IN THE NORTHWEST HALF GOING BY
THE SLIGHTLY FASTER SOLUTIONS. IT IS POSSIBLE THAT IT COULD BE
SLIGHTLY LATER. MOST OF THE MODELS ARE STILL SHOWING GOOD JET
SUPPORT/LIFT OVER THE CENTRAL AND SOUTHEAST PORTION OF THE AREA
BETWEEN 06Z AND 12Z. ALSO SYNOPTIC SCALE AND MESOSCALE FORCING
DOES NOT ARRIVE UNTIL LATER IN THE AFTERNOON.
MID LEVEL MOISTURE IS INCREASING ACROSS THE AREA. HOWEVER...LOW
LEVELS REMAIN INITIALLY DRY. SEEING RAINFALL INCREASE IN COVERAGE
AND INTENSITY ALONG THE FRONT RANGE OF COLORADO AT THIS TIME. SINCE
DEEPER MOISTURE AND LIFT IS SLOWER TO ARRIVE...SLOWED THE ARRIVAL
OF THE RAINFALL AND HIGHER POPS UNTIL LATER THIS AFTERNOON. ALL
MODELS MATCH UP WELL WITH THEIR SYNOPTIC SCALE/MESOSCALE FORCING...
QPF FIELDS...LOCAL POP PROGRAM OUTPUT...AND GEFS/SREF PROBABILITY FOR
MEASURABLE FIELDS SO HAVE HIGHER CONFIDENCE THAT MOST OF THE AREA
WILL RECEIVE MEASURABLE RAINFALL. IT WILL BY NO MEANS BE A SOAKER BUT
MEASURABLE LOOKS PRETTY GOOD.
THE HIGHEST CHANCE/COVERAGE OF PRECIPITATION WILL BE TONIGHT FIRST IN
THE NORTHWEST HALF THEN TRANSITION TO THE SOUTHEAST HALF AFTER 06Z.
TOOK THE MENTION OF THUNDERSTORMS OUT SINCE NOTHING INDICATES ANY
INSTABILITY AT THIS TIME. WHAT IS INTERESTING IS THIS IS
SUBTROPICAL MOISTURE AND PWS COME UP TO 1 TO 1.5 INCHES. EVEN THOUGH
NOT CONVECTIVE IN NATURE...THETA-E LAPSE RATES WOULD INDICATE A
GOOD RESPONSE TO THE LIFT.
CLOUD COVER IS THICKENING ALREADY WITH COLD AIR ADVECTION CONTINUING
THROUGH THE DAY FOLLOWED BY PRECIPITATION INCREASING THIS AFTERNOON.
SO KEPT THE COOL MAXES FOR THE DAY WITH GUIDANCE IN REASONABLE
AGREEMENT. WILL WATCH TRENDS FOR THE REST OF THE SHIFT AND MAY MAKE
FURTHER ADJUSTMENTS BASE ON HOW CURRENT TEMPERATURES ARE DOING.
DEPENDING ON HOW FAST IT CLEARS OUT TONIGHT...IT COULD GET A LITTLE
COOL. LOOKS LIKE THE NORTHERN PORTION WILL AND MADE MINS UP THERE
COOLER.
THURSDAY...PER ANALYSIS AND CURRENT TRENDS...IT IS POSSIBLE THAT THE
MODELS COULD BE TOO FAST IN BRINGING IN AND GETTING RID OF THE
PRECIPITATION. THERE LOOKS TO STILL BE SOME JET LIFT OCCURRING IN THE
SOUTHEAST PORTION THIRD OF THE AREA BETWEEN 12Z AND 18Z. IT WILL BE
CLOSE BUT THERE STILL BE SOME LINGERING JET LIFT NEAR 00Z. SO
SLOWLY DECREASED THE PRECIPITATION THROUGH THE DAY...ENDING BY 00Z.
DEPENDING ON HOW FAST THE CLEARING OCCURS WILL AFFECT THE MAXES. AT
THIS TIME IT LOOKS LIKE THE NORTH WILL BE THE WARMEST. TENDED TO
COMPROMISED BETWEEN THE WARMEST/COOLEST GUIDANCE ACCOUNTING FOR
THE POSSIBILITY OF SLOWER CLEARING.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 403 AM MDT WED SEP 12 2012
THURSDAY NIGHT...LOOKS LIKE THE AREA WILL CLEAR OUT BY 06Z. LOW
DEWPOINTS SINCE UPSTREAM. POSSIBLE THAT DEWPOINTS COULD BE LOWER
THAN WHAT I HAVE IN THERE. WIND FIELD GOES LIGHT AS WELL. KEPT THE
COOL MINS AND POSSIBLE THEY MAY NEED TO BE LOWERED. IF THEY ARE
LOWERED ANY MORE...SOME LOW LYING AREAS MAY SEE PATCHY FROST. NOT
READY TO GO THERE YET THOUGH.
FRIDAY/FRIDAY NIGHT...RIDGE BUILDS IN WITH PLENTY OF SUN. HOWEVER
MODELS CUT OFF A LOW ON THE WESTERN END OF THE TROUGH THAT HAS
MOVED THROUGH. THIS WILL KEEP AN EASTERLY FLOW ALOFT OVER THE AREA.
PLUS IF CIRCULATION ENDS UP BEING FURTHER NORTH...MORE CLOUDS AND
COOLER TEMPERATURES COULD BE IN STORE. AT THIS TIME HAVE THE
WARMEST IN THE NORTH AND COOLEST IN THE SOUTH WITH A TREND OF
COMPROMISING BETWEEN THE WARMER AND COOLER GUIDANCE. INDICATIONS
ARE THAT WIND FIELD COULD BE LIGHT WITH LOW DEWPOINTS STILL IN
PLACE. COULD BE ANOTHER COOL NIGHT WITH MINS POSSIBLY LOWER THAN I
HAVE THEM.
SATURDAY THROUGH TUESDAY...FLOW ALOFT WILL BE NORTHWESTERLY THROUGH
MOST OF THE PERIOD...WITH A TROUGH DIGGING OVER THE REGION LATE IN
THE PERIOD. A COLD FRONT WILL MOVE THROUGH THE AREA ON
MONDAY...BRINGING WITH IT A CHANCE FOR SHOWERS AND THUNDERSTORMS.
STILL A LOT OF UNCERTAINTY REGARDING TEMPERATURES ON MONDAY...BUT
BETTER AGREEMENT THAN YESTERDAY WITH THE TIMING OF THE FRONT.
GUIDANCE IS TRENDING COOLER...SO HAVE ADJUSTED HIGHS DOWNWARD A FEW
DEGREES ACROSS MUCH OF THE REGION. TEMPERATURES DURING THE PERIOD
WILL BE WARMEST ON SUNDAY WITH HIGH TEMPERATURES NEAR NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1150 AM MDT WED SEP 12 2012
SOME BRIEF VISIBILITY REDUCTIONS IN BLOWING DUST HAVE BEEN NOTED AT
BOTH KGLD AND KMCK WITH GUSTY NORTH WINDS BEHIND A COLD FRONT...THIS
MAY CONTINUE UNTIL MID AFTERNOON AS WINDS DIMINISH. CEILINGS WILL
GRADUALLY LOWER THROUGH THE AFTERNOON AT BOTH TERMINALS AS SCATTERED
RAIN SHOWERS ASSOCIATED WITH UPPER SYSTEM MOVES IN FROM COLORADO.
LOW LEVEL ARE STARTING OUT RATHER DRY...SO MVFR MAY NOT BE REACHED
UNTIL MID OR LATE AFTERNOON...AND IFR CEILINGS POSSIBLE TONIGHT AS
LIGHT RAIN CONTINUES.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DDT/BULLER
LONG TERM...BULLER/CJS
AVIATION...024
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1230 PM CDT WED SEP 12 2012
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
QUITE A DIFFERENCE A DAY MAKES WITH EXPECTED TEMPERATURES TODAY AT
LEAST 20 DEGREES COOLER THAN YESTERDAY. CDFNT NOW PASSING ACROSS
THE METRO WITH TEMPS FALLING A GOOD 10 DEGREES IN AN HOUR OR TWO IN
WAKE OF FROPA. WITH BLANKET OF POST FRONTAL CLOUDS DON`T EXPECT MUCH
IN THE WAY OF TEMPERATURE RECOVERY TODAY. COOLING IN WAKE OF FRONT
IS ALSO BEING AIDED BY VERY LOW DEW POINT DEPRESSIONS YIELDING HIGH
EVAPORATIVE COOLING ACROSS AREAS WHICH HAVE RECEIVED LIGHT PRECIP
OVERNIGHT.
-RA AND EVEN SOME ISOL THUNDER REMAINS IN A SW-NE BAND ACROSS SODAK
THEN ACROSS CENTRAL MN IN PLUME OF ELEVATED MOISTURE. PRECIP
AMOUNTS HAVE GENERALLY BEEN A FEW HUNDREDTHS OF AN INCH...BUT ARND
.10 AT BENSON...APPLETON AND MADISON SO FAR. HRRR HAS BEEN DOING A
PRETTY GOOD JOB ON HANDLING THIS AREA OF PCPN WHICH HAS SOME SUPPORT
FROM RIGHT ENTRANCE REGION OF UPPER JET. INCREASED POPS FOR THE
MORNING ACROSS CENTRAL MN.
ANOTHER AREA OF SHWRS AND ISOL THUNDER HAS ALSO BEEN BEEN DEVELOPING
IN NW IA BACK INTO NEB. THIS AREA SHOULD CONTINUE TO DEVELOP DURING
THE DAY TODAY AS UPPER WAVE LIFTS OUT CO BACKING MID LEVEL WINDS AND
GENERATING FAVORABLE UPGLIDGE AROUND THE 305K SURFACE. INCREASED
POPS MAINLY ACRS S MN INTO THE KEAU AREA FOR LATER THIS MORNING AND
AFTN.
FOR THURSDAY A SHARP AND FAST MOVING UPPER TROF DIVES OUT OF THE
PRAIRIE PROVINCES OF CANADA TO NEAR NW CORNER MN BY 12Z AND INTO WI
BY 00Z THURSDAY. NOT MUCH MOISTURE AVAILABLE FOR PCPN...BUT
CONSIDERING PATH OF THIS FEATURE ACROSS AREA DURING THE DAYLIGHT AND
B24 500MB TEMPS...IT IS WORTHY OF A MENTION OF SLIGHT CHC POPS AND
ISOL THUNDER.
MODERATING TEMPERATURES OVER THE WEEKEND AS SOUTHERLY FLOW DEVELOPS
AHEAD OF NEXT IMPRESSIVE LOOKING COLD FRONT. FRONT COMES ACROSS
AREA SUNDAY NIGHT MONDAY BRINGING A CHANCE POPS AND SOME QUITE
CHILLY AIR AS 1000-500 MB THICKNESS DROPS TO 540DM ACROSS N MN.
LOOKING LIKE COOL START TO THE UPCOMING WEEK AS WE GET DEEP INTO NW
FLOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
BAND OF LIGHT RAIN OVER SOUTHERN MINNESOTA...SHOULD DROP SOUTH THIS
AFTERNOON...ENDING LAST AT KEAU. CLEARING THEREAFTER. IF IT CLEARS
FAST ENOUGH IN THE EAST...COULD SEE SOME FOG DEVELOP...IN THOSE
SEEING THE MOST RAIN....MAINLY WESTERN WISCONSIN. WILL LEAVE OUT FOR
NOW. NEXT SYSTEM MOVES INTO THE AREA THURSDAY AFTERNOON...WITH MID
CLOUDS AGAIN. LOWER LEVELS REMAIN DRY...SO ONLY SMALL CHANCE OF A
SHOWER POSSIBLE ACROSS CENTRAL MN. NORTHERLY WINDS OVER THE SOUTH
WITH WEST/NORTHWEST WINDS OVER THE NORTHERN CWA...AS DRIER AIR WORKS
INTO THE AREA. COULD SEE SOME GUSTS AROUND 20 MPH NORTHWEST INTO THE
AFTERNOON.
KMSP...LIGHT RAIN SHOWERS THROUGH ABOUT 22Z AND CEILINGS REMAIN VFR
THROUGH THE PERIOD. SHOULD SEE CLEARING THIS EVENING AS SYSTEM
EXITS. NEXT TROUGH SWINGS INTO THE AREA THU AFTERNOON. WILL DRAW
IN SOME MID CLOUDS BUT WILL REMAIN DRY FOR NOW. WESTERLY WIND WITH
RAIN BAND...DECREASING THIS EVENING AND INCREASING AGAIN THURSDAY
MORNING AND BECOMING NORTHWEST AS NEXT TROUGH MOVES THROUGH.
/OUTLOOK FOR KMSP/
.THURSDAY...VFR. ISOLD AFTN SHRA POSSIBLE. WINDS NW AT 05-10 KTS.
.FRIDAY...VFR. 5-10KT NW WINDS BECOMING SW.
.SATURDAY...VFR. WINDS S AT 10KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BAP/DE
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1236 PM CDT Wed Sep 12 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Today through Friday...
A band of weak elevated instability ahead of a surface cold front in
central Nebraska and northwest Iowa this morning has fired up a few
very light showers across the northwest corner of the forecast area.
The HRRR indicates these showers may persist just ahead of the
boundary for a few hours before mixing begins to eliminate the
instability, so have added a small chance of very light showers to
the far northwest through late morning. For the rest of the day,
above normal temperatures and breezy south winds can be expected
again, especially across the southwestern corner of the CWA. Surface
low pressure at the base of a deep trough over the northern Rockies
will push eastward into central Kansas today, resulting in the
tighter pressure gradient in our southwest, and could also provide
additional forcing needed to fire up some isolated convection mainly
west of the forecast area late this afternoon. As the main trough
dives to the southeast, the surface cold front will push through
southeast Nebraska and western Iowa, arriving at the northwest
corner of the CWA by 00z. Surface-based instability will build ahead
of the front this afternoon, which may result in isolated convective
initiation along the boundary as it enters the forecast area. Any
isolated development that occurs in central Kansas may also build
eastward during the evening, eventually merging with precipitation
along the cold front. However, surface-based convection will likely
not sustain after sunset, and the bulk of precipitation should occur
behind the surface front as the main wave moves through.
Although showers still look likely through Thursday as the main
trough makes southeastward progress across the CWA, precipitation
chances will decrease as the upper wave weakens and the best energy
transitions further east, towards the Great Lakes region. Have
gradually decreased the chance of precipitation from Thursday
morning through Friday, and also lowered precipitation amounts as
rainfall becomes more scattered. As the wave weakens, it also slows
across the region, so have slowed the southeastward progress of
rainfall chances, especially Thursday night and Friday. Lingering
showers should exit the region altogether by early Friday afternoon.
Temperatures will fall dramatically following cold frontal passage
on Thursday, especially with cloud cover and precipitation filling
in behind the surface front. Highs Thursday may only recover a few
degrees from overnight lows, especially in areas where the surface
front passes during the early morning. Temperatures will be slow to
recover this weekend as the midlevel boundary remains to our
southwest, keeping cooler air entrenched across the region.
Saturday through Tuesday...
A few model solutions break off the southwestern extent of the wave
on Friday, and keep a small disturbance over the Southern High
Plains from Friday night through Saturday. As the southwesterly jet
across the Texas panhandle increases Saturday, the lower pressure
deepens and begins to eject northeastward, possibly bringing
precipitation chances back into our south by early Sunday.
Afterward, another deep trough moves through the central U.S.,
bringing another cold front and additional chances of showers from
Monday morning through Tuesday. Temperatures will have little chance
to rebound back towards normal values early this week before the
next cold front comes through, which indicates mainly below normal
temperatures through the forecast period.
Laflin
&&
.AVIATION...
For the 18Z TAFs...For the rest of the daylight hours VFR conditions
will prevail at the terminals. Errant showers still wafting across
Northwest Missouri do not look likely to effect the KSTJ terminals at
this time, so have avoided mentioning them. Otherwise, focus is on
the arrival of a cold front tonight and the rain that will be
following it. Frontal passage looks to occur after midnight, with
winds become somewhat gusty behind the advancing front. Dry air in
place across the region should limit early morning storms to on-
again-off-again showers, though as we move into the daylight morning
hours rain will likely become more widespread and heavier as
saturation of the boundary layer occurs. Confidence on the ceilings
is rather low, so left them on high the edge of MVFR.
Cutter
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
327 PM CDT WED SEP 12 2012
.DISCUSSION...
UPPER LEVEL TROF SHOULD EXIT THE FCST AREA BY 03Z-06Z WITH 1028 MB
HIGH PRESSURE BUILDING IN OVERNIGHT. RECENT RAINS AND CALM
BOUNDARY LAYER WINDS IN THE WETTER AREAS MIGHT BE SUFFICIENT FOR
PATCHY FOG. LIMITING FACTOR MIGHT BE STRONG SUBSIDENCE WHICH WOULD
NEGATE MOISTURE POOLING.
GIVEN HIGHS IN THE 50S AND 60S THIS AFTERNOON FROST OR FREEZE
POTENTIAL TONIGHT COULD BECOME VERY HIGH IF SKIES CLEAR AS RAPIDLY
AS SOME EARLIER SOLNS OF THE RAP MODEL SHOWED. THE LATEST RAP IS
TRAPPING MOISTURE IN THE BOUNDARY LAYER BENEATH THE SFC HIGH AT
06Z WHICH IS A FOG SIGNATURE. FOR NOW SOME OF THE COOLER GUIDANCE
SUGGESTED PATCHY FROST ACROSS SHERIDAN COUNTY...NOTHING MORE AND
PATCHY FOG IS IN PLACE ACROSS THE WETTER AREAS.
HIGH PRESSURE AND CLEAR SKIES WILL DRIFT ACROSS THE FCST AREA
THURSDAY WITH HIGHS IN THE MID 70S.
FRIDAY THROUGH SUNDAY...ANOTHER SLOWLY EVOLVING NRN PLAINS LOW
PRESSURE SYSTEM WILL DROP INTO WCNTL NEB BY SUNDAY AFTERNOON. THE
TIMING OF THE COLD FRONTAL PASSAGE SUNDAY AFTERNOON SUGGESTS NO
TORCH FEST FOR THE FORECAST AREA AT THIS TIME. SATURDAY MIGHT
ACTUALLY BE THE WARMEST DAY WITH 90F MAYBE ACROSS NORTHWEST
NEB...80S ELSEWHERE. UPPER 70S MODERATING TO THE MID 80S SATURDAY
AND SUNDAY WOULD APPEAR TO BE THE OPERATIVE MODE AT THIS TIME.
WE WOULD EXPECT TO SEE 580DM 10-5MB THICKNESSES FOR HIGHS NEAR OR
ABOVE 90F BUT WE ARE STILL OPERATING IN THE LOW 570S.
MONDAY THROUGH WEDNESDAY...A COLD FRONT WILL SLICE THROUGH THE FCST
AREA SUNDAY AND SUNDAY NIGHT. THERE MAY BE SUFFICIENT RETURN
MOISTURE FOR ISOLD TSTMS SUNDAY NIGHT AND ISOLATED SHRA MONDAY.
TEMPS MONDAY STAY IN THE 60S AS A STRONG CANADIAN HIGH DROPS
THROUGH THE HIGH PLAINS. THE PACIFIC NORTH AMERICAN AMPLIFICATION
WILL BE IN FULL SWING THROUGH WEDNESDAY. MODEL CONSENSUS SUGGESTS
THE RIDGE AXIS LINING UP ACROSS BRITISH COLUMBIA AND THIS WOULD
DIVERT THE COLDEST AIR INTO THE UPPER MIDWEST. THE GEM POSITIONS
THE AXIS FARTHER WEST...IS MORE AMPLIFIED AND TRAPS SOME DYNAMICS
ACROSS WY PRODUCING SNOW.
SFC HIGH PRESSURE WILL MOVE QUICKLY SOUTH AND EAST TUESDAY WITH
LOW PRESSURE AND RETURN FLOW DEVELOPING WEDNESDAY. OTHER THAN THE
RAIN TONIGHT AND ISOLATED CHANCES LATE SUNDAY AND MONDAY THE
FORECAST IS DRY.
&&
.AVIATION...
LIGHT TO MODERATE RAIN SHOWERS ALONG A KONL TO KOGA LINE AT MID
AFTERNOON...WHICH WILL CONTINUE TO SLOWLY TRACK SOUTHEAST DURING THE
LATE AFTERNOON HOURS. -SHRA AND MVFR CIGS WILL BE POSSIBLE AT KLBF
THROUGH 23Z...AFTER THAT TIME GRADUAL CLEARING IS EXPECTED. AT
KVTN...SKIES BEGIN TO CLEAR AS MUCH DRIER AIR MOVES INTO THE AREA
OVERNIGHT. VFR CONDITIONS WILL PREVAIL DURING THE OVERNIGHT AND
THROUGH TOMORROW MORNING.
&&
.FIRE WEATHER...
DID GET RAIN TODAY IN PARTS OF THE FORECAST AREA...BUT MOST
LOCATIONS DID NOT RECEIVE ENOUGH TO WET FUELS TO THE POINT OF BEING
NOT CRITICALLY DRY. ALSO...WHAT WETTING DID OCCUR...WITH SEE THE
OPPORTUNITY TO DRY OUT ON THURSDAY WITH MOSTLY SUNNY SKIES AND HIGHS
IN THE 70S.
A WARMING TREND IS EXPECTED FOR THE WEEKEND...WITH HIGHS IN THE 80S
/AND POSSIBLY A FEW 90S/ FOR SATURDAY AND SUNDAY. DEWPOINTS SHOULD
STAY FAIRLY LOW...IN THE 30S AND LOW 40S THROUGH THIS PERIOD SO
AFTERNOON RELATIVE HUMIDITY WILL DROP TO 15 TO 20 PERCENT ACROSS
PORTIONS OF THE AREA THROUGH FRIDAY...SATURDAY...AND SUNDAY. AM NOT
LOOKING AT PARTICULARLY STRONG WINDS THESE DAYS...BUT COULD GET
GUSTS TO THE 20 TO 25 MPH RANGE EACH DAY.
ANOTHER STRONG SYSTEM THEN LOOKS TO MOVE THROUGH SUNDAY NIGHT...WITH
A WIND SHIFT TO THE NORTH AND MUCH COOLER TEMPERATURES FOR MONDAY.
SUNDAY NIGHT AND MONDAY WILL BE THE NEXT CHANCE FOR RAIN...ALTHOUGH
RAINFALL AMOUNTS DO NOT LOOK TOO IMPRESSIVE AT THIS POINT.
THE WEATHER LOOKS TO BE MARGINAL AT BEST FOR CRITICAL FIRE WEATHER
CONDITIONS OVER THE NEXT WEEK. HOWEVER...WITH THE CONTINUED DRYNESS
OF FUELS...EVEN MARGINAL FIRE WEATHER CONDITIONS CAN...AND HAS
CAUSED EXTREME FIRE BEHAVIOR. THEREFORE...WILL BE CLOSELY MONITORING
THE FORECAST FOR FRIDAY THROUGH SUNDAY FOR THE NEED FOR FIRE WEATHER
HEADLINES.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...BROOKS/MARTIN
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
101 PM CDT WED SEP 12 2012
.AVIATION...
INITIAL CONCERNS WILL BE RAIN AND SHOWERS AND SOME EMBEDDED
THUNDER AND WINDS. WILL INCLUDE RAIN AND SHOWERS AT ALL THREE TAF
SITES ALONG WITH SOME PATCHY MVFR CIGS. THERE WILL BE
CONVECTION...HOWEVER DUE TO IT/S ISOLATED NATURE WILL NOT MENTION
IN TAFS UNTIL IT IS MORE CERTAIN. THE SURFACE FRONT IS THROUGH
THE SITES...HOWEVER THE UPPER LEVEL DYNAMICS WILL SUPPORT THE
PRECIPITATION BEHIND THE FRONT. NORTHEAST WINDS WILL BE
STRONG...10 TO 20KTS SUSTAINED WITH GUSTS TO AROUND 25KTS. THE
SURFACE WINDS WILL DIMINISH THIS EVENING AT KOFK AND AFTER 06Z AT
KOMA AND KLNK. DECREASING WINDS AND CLOUDS COULD LEAD TO FOG
THURSDAY MORNING. DUE TO THE ACTIVE WEATHER IN THE FIRST
12HRS...WILL NEED TO LOOK AT MORE CLOSELY IN LATER TAF FORECASTS.
&&
.PREV DISCUSSION... /ISSUED 245 AM CDT WED SEP 12 2012/
DISCUSSION...
COLD FRONT EXTENDED FROM NORTHWEST IOWA ACROSS NORTHEAST NEBRASKA
INTO SOUTH CENTRAL NEBRASKA ALONG A KSUX TO KEAR LINE AT 07Z.
SCATTERED SHOWERS AHEAD OF THE FRONT HAVE BECOME MORE NUMEROUS
DURING THE PAST HOUR OVER SOUTHEAST NEBRASKA INTO SOUTHWEST IOWA.
00Z GFS AND 04Z HRRR APPEAR TO BE SIMILAR IN HAVING THE FRONT NEAR
A KOMA TO KHJH LINE BY 12Z...A BIT FASTER THAN THE 00Z NAM.
WILL ADD CHANCE OF SHOWERS AND ISOLATED THUNDER TO AREAS SOUTH OF
THE FRONT THIS MORNING BASED ON RADAR TRENDS AND SHORT RANGE
MODELS. WILL ALSO LIKELY TREND HIGHS TODAY TOWARD THE SOMEWHAT
COOLER GFS GUIDANCE BASED ON FASTER TIMING OF THAT MODEL.
OTHERWISE...STILL LOOKS GOOD FOR WIDESPREAD RAIN ACROSS MUCH OF
THE AREA TONIGHT WITH SYSTEM MOVING OUT OF SOUTHEAST AREAS
THURSDAY MORNING. FAIR AND DRY AFTER THAT WITH COOLER TEMPERATURES
HANGING AROUND FOR A CHANGE.
IN THE EXTENDED...AREA REMAINS UNDER THE INFLUENCE OF COOLER
NORTHWEST FLOW WITH ANOTHER STRONG TROUGH MOVING THROUGH THE
REGION EARLY NEXT WEEK. STILL SOME CHANCE OF SHOWERS WITH COLD
FRONT ON MONDAY WITH LOW POPS MAINTAINED FOR THAT PERIOD. SOME
DIFFERENCES BETWEEN THE GFS AND EURO IN HANDLING THIS FASTER FLOW
SO WILL HAVE TO SEE HOW CONSISTENT FUTURE MODEL RUNS BEHAVE.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
110 PM CDT WED SEP 12 2012
.DISCUSSION...
18Z TAF UPDATE BELOW.
&&
.AVIATION...
AN ACTIVE MORNING CONVECTION-WISE WILL BE JUST THE BEGINNING OF
THESE PASSING PERIODIC SHOWERS AND OCCASIONAL THUNDERSTORMS
THROUGH THIS PERIOD. THE GREATEST MOISTURE RESIDES JUST OFFSHORE
...POOLING UP OVER THE NEARSHORE WATERS AND IS SCHEDULED TO COME
ONSHORE THROUGH THURSDAY PER WEAK ANTICYCLONIC MID-LEVEL FLOW
PULLS THIS HIGHER MOISTURE NORTHWARD. A DIFFUSE WARM FRONTAL
BOUNDARY WILL CREEP ONSHORE AS WELL AND...WITH THIS ADDITIONAL
(ALONG OR SOUTH OF I-10) LOWER LEVEL FOCUS WITHIN AN MORE TROPICAL
AIR MASS...IT WILL NOT TAKE MUCH TO (RE)INITIATE PRIMARILY SHRA
WITH MID-MORNING THROUGH LATE AFTERNOON TSRA. CONDITIONS WITHIN
ANY MODERATE TO STRONG THUNDERSTORM (+TSRA) WILL LOWER VICINITY
VISBIES DOWN TO AROUND 1-2 SM...LOWER CEILINGS TO MVFR...AND WINDS
WILL QUICKLY BECOME VARIABLE AT 25-30 KTS. 31
&&
.PREV DISCUSSION... /ISSUED 1018 AM CDT WED SEP 12 2012/
DISCUSSION...
13Z SURFACE MAPS SHOWS WEAK CONVERGENCE ALONG THE COAST AND
SCATTERED SHRA/TSRA INCREASING IN COVERAGE OVER THE COASTAL
COUNTIES. 850 MB MOISTURE LOOKS RATHER PLENTIFUL OVER THE EASTERN
HALF OF THE STATE. 700 MB MOISTURE ALSO LOOKS RATHER DEEP FROM
CRP TO LCH. 4 KM WRF AND NMM DON`T SHOW MUCH PRECIP COVERAGE TODAY
WHILE THE LATEST RAP 13 SHOWS GOOD PCPN COVERAGE. 12Z SOUNDINGS
SHOW LOW CONVECTIVE TEMPS...BETWEEN 85 AND 87 DEGREES WITH PW
VALUES BETWEEN 1.8 AND 1.9 INCHES. WEAK CAPPING IS NOTED NEAR 600
MB. WILL LEAN TOWARD THE MORE AGGRESSIVE RAP SINCE THE 12Z
SOUNDINGS LOOK TO BE SUPPORTIVE OF HIGHER RAIN CHANCES. TEMPS LOOK
TO BE ON TRACK ALTHO INCREASED CLOUDS AND RAIN MAY KEEP MAX TEMPS
A LITTLE COOLER. NEW ZONES OUT BY 1030 AM. 43
&&
PREV DISCUSSION... /ISSUED 452 AM CDT WED SEP 12 2012/
DISCUSSION...
STRONG WAA/MOISTURE RETURN HAS BROUGHT SCT SHRA TO THE SRN HALF OF
SE TX LAST NIGHT. THIS PATTERN EXPECTED TO REMAIN IN PLACE FOR THE
NEXT FEW DAYS WITH GULF MOISTURE DEEPENING THROUGHOUT. THIS SHOULD
HELP TO INCREASE POPS BY THE END OF THE WEEK ACROSS OUR FA. ALL OF
THIS SEEMS TO BE A PRELUDE TO A RATHER WET WEEKEND AS A COLD FRONT
AND AN ASSOCIATED COASTAL SFC LOW IN/ACROSS THE REGION. THIS FRONT
FCST TO STALL AT/NEAR THE COAST SAT WITH A LOW PROGGED TO DEVELOP/
FORM ALONG THE BOUNDARY AND MOVE UP THE COAST ON SUN. MODELS ARE A
BIT HINKY WITH THE TIMING OF CLEARING...SO HAVE OPTED TO GO SLOWER
(KEEPING POPS IN THE FCST THRU MON). THE MAIN UNCERTAINTY SEEMS TO
BE HOW WE ARE GOING TO GET PCPN RATHER THAN IF WE ARE GOING TO GET
PCPN. (I.E. ALL SIGNS POINT TO A WET WEEKEND.) 41
MARINE...
WARM FRONT OVER THE COASTAL AREAS EARLY THIS MORNING LIFTING NORTH
TODAY WILL DEEPEN THE MOISTURE ACROSS THE UPPER TEXAS COASTAL
WATERS LEADING TO SCATTERED SHOWERS AND THUNDERSTORMS. CAPE OF
2000-3500 J/KG THIS MORNING WITH A SLIGHTLY BACKED LL FLOW COULD
POSE A THREAT OF TROPICAL FUNNEL CLOUDS ESPECIALLY IN THE AREAS TO
THE EAST OF FREEPORT THROUGH HIGH ISLAND. EASTERLY FLOW DEVELOPING
TONIGHT AND THURSDAY AS HIGH PRESSURE TO THE NORTHEAST STEERS FLOW
WITH A COLD FRONT SLIPPING SOUTH ACROSS THE RED RIVER AND INTO THE
UPPER TEXAS NEARSHORE WATERS SATURDAY AFTERNOON OR SUNDAY
MORNING. GFS/ECMWF DIFFER DRAMATICALLY BY MONDAY AND FAVORING THE
ECMWF SOLUTION WITH A STATIONARY FRONTAL BOUNDARY WITH FRONTAL WAVES
IN THE COASTAL WATERS.
45
AVIATION...
SHORT TERM EXPECT THAT SHOWERS WILL CONTINUE TO DEVELOP IN THE
LEADING EDGE OF THE DEEPER MOISTURE ALONG THE WARM FRONT THIS
MORNING OVER THE HOU-GLS TERMINALS THEN SPREAD INLAND LATE MORNING
AND BEYOND. SOME PATCHY MVFR CIGS POSSIBLE THIS MORNING THOUGH
PRIMARILY ASSOCIATED WITH THE PASSING SHOWERS. VCSH SHOULD COVER IT
FOR NOW WITH TEMPO SHRA CONDITIONS AT LBX/GLS/SGR/HOU BETWEEN 10-
14Z GIVEN THE CURRENT TRENDS ON RADAR. SHOWERS AND THUNDERSTORMS
PROBABILITY INCREASING MID TO LATE MORNING NEAR IAH AND THEN THROUGH
THE AFTERNOON. EASTERLY FLOW THIS MORNING BECOMING SSE AS MOIST FLOW
DEEPENS THEN BACKS OVERNIGHT WITH SCATTERED SHRA/ISO TSRA AGAIN
THURSDAY MORNING.
45
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 74 91 72 88 70 / 20 40 50 50 40
HOUSTON (IAH) 74 90 72 88 71 / 30 40 40 50 40
GALVESTON (GLS) 79 88 78 87 77 / 30 40 40 50 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...43
AVIATION/MARINE...31
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1241 PM CDT WED SEP 12 2012
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
339 AM CDT WED SEP 12 2012
MAIN FORECAST CONCERNS ARE PRECIPITATION AND TEMPERATURE TRENDS
THROUGH THURSDAY...THEN POTENTIAL FOR VALLEY FOG AND PATCHY FROST
THURSDAY NIGHT INTO FRIDAY MORNING.
AS OF 08Z WEDNESDAY...WATER VAPOR IMAGERY AND RAP 500MB HEIGHT
FIELDS DEPICT A LARGE TROUGH ACROSS SOUTHERN CANADA INTO THE
NORTHERN PLAINS WHILE A LARGE RIDGE OF HIGH PRESSURE WAS CENTERED
ACROSS THE SOUTHEAST US. IN-BETWEEN...A PLUME OF SOUTHWEST MONSOONAL
MOISTURE WAS BEING ADVECTED NORTHEAST TOWARDS THE FORECAST AREA
WHERE PRECIPITABLE WATER VALUES RANGED FROM 0.75 TO 1.1 INCHES / 80
TO 120 PERCENT OF NORMAL / PER GOES SOUNDER IMAGERY. A 250MB JET
STREAK WAS NOTED ACROSS NORTHERN NORTH DAKOTA INTO EXTREME SOUTHWEST
ONTARIO. AT THE SURFACE...A COLD FRONT STRETCHED FROM NORTHWEST
WISCONSIN TO THE TWIN CITIES TO OMAHA NEBRASKA WHERE COMBINED WITH
INCREASING 850 MB TRANSPORT AHEAD OF THE FRONT AND MID TO UPPER
LEVEL FRONTOGENETICAL SUPPORT WAS GENERATING POST FRONTAL SHOWERS.
MEANWHILE...SOME WARM AIR ADVECTION SHOWERS AHEAD AND ALONG THE
FRONT WERE DEVELOPING ACROSS NORTHERN IOWA INTO SOUTHERN MINNESOTA.
DEWPOINT DEPRESSIONS REMAINED 25 TO 30F BUT A FEW SITES WERE
REPORTING PRECIPITATION UNDER 8 TO 10 KFT CLOUD BASES. LATEST IR
IMAGERY SHOWS HIGH CLOUDS ACROSS MUCH OF THE FORECAST AREA.
TODAY AND TONIGHT...EXCELLENT AGREEMENT BETWEEN THE LATEST
NAM/GFS/ECMWF/SREF/RAP DEPICTING THE COLD FRONT MAKING A STEADY
PROGRESS SOUTHEAST THROUGH THE FORECAST AREA SUCH THAT BY 12Z IT
SHOULD BE ALONG A BLACK RIVER FALLS TO LA CROSSE WISCONSIN TO
CHARLES CITY IOWA LINE. TEMPERATURES ARE TRICKY WITH CONTINUED
SOUTHWEST FLOW EXPECTED AHEAD OF THE FRONT WHERE LOCATIONS IN
NORTHEAST IOWA AND EXTREME SOUTHWEST WISCONSIN SHOULD REMAIN IN WARM
SECTOR FOR MUCH OF THE DAY...TOPPING OUT IN THE LOWER TO MIDDLE
80S. NON-DIURNAL TREND ON TRACK FOR OTHER SPOTS WHERE HIGHS SHOULD
OCCUR AROUND 18Z...FALLING INTO THE MIDDLE 60S BY 21Z. AS DEWPOINTS
CRASH INTO THE UPPER 40S LATE THIS AFTERNOON AND PRECIPITATION
BEGINS...TEMPERATURES LOOK TO QUICKLY DROP OFF.
DYNAMICS LOOK GOOD WITH FORECAST AREA FAVORABLY POSITIONED IN THE
RIGHT ENTRANCE REGION OF THE 250MB JET. A NW-SE CROSS SECTION
THROUGH THE REGION SHOWS STRONG FRONTOGENETICAL BAND WITH IDEAL
FRONTOLYSIS/FRONTOGENETICAL CIRCULATION SETTING UP ACROSS THE AREA
BEGINNING THIS EVENING. STRONG ISENTROPIC UPGLIDE ON THE 305-315K
SURFACES IS PRESENT ALONG WITH DECENT 850 MB MOISTURE TRANSPORT.
DESPITE SOME LOW LEVEL DRY AIR CONCERNS INITIALLY...THAT SHOULD BE
OVERCOME SUCH THAT SHOWERS WILL DEVELOP / MOVE INTO SOUTHEAST
MINNESOTA AND WESTERN WISCONSIN BETWEEN 22-00Z...THEN SAG SOUTHEAST
THROUGH THE NIGHT. THE LATEST MESO MODELS ARE IN GOOD AGREEMENT WITH
THIS SCENARIO AS WELL. REGARDING RAINFALL TOTALS THROUGH THE
EVENT...A NORTH/SOUTH GRADIENT SHOULD SET UP AS BETTER FORCING/LIFT
ACROSS IOWA INTO SOUTHERN WISCONSIN. TOTALS AROUND 1/10 OF AN INCH
ACROSS NORTH CENTRAL WISCONSIN....TO 1/3 TO 1/2 ALONG THE I-90
CORRIDOR...THE UPWARDS OF 3/4 OF AN INCH LOOK PROMISING FOR THE
AREA.
THURSDAY AND FRIDAY...BY 12Z THURSDAY...THE BULK OF THE
PRECIPITATION SHOULD BE ORIENTED THROUGH CENTRAL WISCONSIN TO
NORTHEAST IOWA. TIMING THE PROGRESS OF THIS PRECIPITATION OUT OF THE
FORECAST AREA IS A BIT TRICKY. THIS IS MOST LIKELY DUE TO MODEL
TIMING DIFFERENCES INCREASING ON HOW THE NEXT SHORTWAVE...CURRENTLY
IN NORTHWEST ALBERTA...DIVING SOUTHEAST DURING THE DAY THURSDAY IS
HANDLED. THE 12.00Z NAM IS A SLOWER OUTLIER...WHILE THE 12.00Z
GFS/CANADIAN/ECMWF ARE IN GOOD AGREEMENT. HAVE DISCOUNTED THE NAM
FOR THE TIME BEING...GIVEN TRENDS OVER THE PAST DAY TO BE FASTER.
THE HIGHEST PRECIPITATION CHANCES AFTER 15Z THURSDAY LOOK TO BE
SOUTH/EAST OF A SPARTA WISCONSIN TO OELWEIN IOWA LINE. A COOL DAY ON
TAP FOR THE AREA WITH MOSTLY CLOUDY TO CLOUDY SKIES UNDER COLD AIR
ADVECTION AND 850MB TEMPS PROGGED TO BE 5-8C. AREAS SOUTH/EAST WILL
BE THE COOLEST WITH MORE CLOUDS/RAIN...AND PROBABLY WILL ONLY MAKE
IT TO 60F AT BEST. AS THE NORTHWEST ALBERTA SHORTWAVE DIVES THROUGH
MINNESOTA DURING THE AFTERNOON AND COMBINES WITH DIURNAL
HEATING...SCATTERED SHOWERS ARE POSSIBLE...MAINLY CONFINED TO THE
NORTHWEST AREAS. STEEPER LAPSE RATES AND MAYBE SOME INSTABILITY TO
WORK WITH COULD PRODUCE A RUMBLE OR TWO OF THUNDER AS WELL.
THE NORTHWEST ALBERTA SHORTWAVE QUICKLY PIVOTS THROUGH THE NORTHERN
PLAINS LATE THURSDAY AND BY 06Z FRIDAY SHOULD BE CENTERED ACROSS
WISCONSIN. AT THE SURFACE...BUILDING CANADIAN HIGH PRESSURE THURSDAY
NIGHT INTO FRIDAY MORNING WILL BRING SOME OF THE COLDEST AIR OF THE
AUTUMN SEASON THUS FAR. THE COMBINATION OF PRECIPITABLE WATER VALUES
DROPPING TO A 0.5 INCH OR LESS...DIMINISHING WINDS WITH THE HIGH
PRESSURE AREA BUILDING IN AND CLEARING SKIES WILL ALL HELP
TEMPERATURES TO TANK. LOWS LOOK TO DROP DOWN TO THE LOWER 40S TO
AROUND 40 FOR MOST LOCATIONS. ALONG AND NORTHEAST OF THE I-94
CORRIDOR IN WISCONSIN...THE TYPICAL COLD SPOTS COULD EVEN SEE SOME
PATCHY FROST...THOUGH THIS WOULD ALL HINGE ON THE SURFACE HIGH
POSITION. RIVER VALLEY FOG WOULD ALSO BE A CONCERN GIVEN THIS
SYNOPTIC SETUP...ESPECIALLY GIVEN EXPECTED RAINFALL OVER THE NEXT 36
HOURS AND THE COOLER AND CLOUDIER DAY EXPECTED THURSDAY. RIGHT NOW
THE GFS IS A FASTER OUTLIER IN BRINGING IN THE SURFACE HIGH...MAKING
ITS SOLUTION THE MOST FAVORABLE FOR WIDESPREAD VALLEY FOG AND ALSO
MORNING FROST ACROSS NORTH CENTRAL WISCONSIN. DEFINITELY SOMETHING
TO WATCH CLOSELY IN THE NEXT FORECAST RUNS. FOR NOW HAVE ONLY
INCLUDED AREAS OF FOG FOR THE WISCONSIN RIVER AND ITS TRIBUTARIES...
AND PATCHY FOG FOR THE MISSISSIPPI RIVER. FRIDAY LOOKS TO BE A VERY
PLEASANT DAY FOR THE ENTIRE UPPER MIDWEST WITH THE HIGH PRESSURE
DRIFTING OVERHEAD...PROVIDING LIGHT WINDS. 850MB TEMPS OF 6-8C AND
PLENTY OF SUN SHOULD RESULT IN HIGHS SLIGHTLY BELOW NORMAL...IN THE
UPPER 60S TO LOWER 70S.
QUIET WEATHER LOOKS TO PERSIST INTO FRIDAY NIGHT WITH THE HIGH
PRESSURE REMAINING NEARBY. LOW PRECIPITABLE WATER VALUES ARE STILL
SUGGESTED...SO ANOTHER COOL NIGHT IS EXPECTED WITH LOWS IN THE UPPER
30S AT THE TYPICAL COLD SPOTS AND LOW TO MID 40S ELSEWHERE. MAY
AGAIN BE DEALING WITH VALLEY FOG AND FROST.
.LONG TERM...SATURDAY THROUGH TUESDAY NIGHT
339 AM CDT WED SEP 12 2012
12.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES ARE IN MUCH BETTER
AGREEMENT ON THE UPPER LEVEL PATTERN COMPARED TO THE PAST FEW DAYS
FOR THE LONG TERM FORECAST. THERE STILL ARE SOME ISSUES...MOSTLY
IMPACTING TUESDAY AND TUESDAY NIGHT.
TO BEGIN THE LONG TERM FORECAST...NEARLY ZONAL FLOW EXISTS WITH THE
WESTERLIES RUNNING ACROSS SOUTHERN CANADA. WITHIN THIS FLOW...
THOUGH...THERE IS A POTENT SHORTWAVE CROSSING NORTHERN SASKATCHEWAN
WITH INDICATIONS OF TROUGHING BEGINNING TO FORM OVER WESTERN
ALBERTA. THIS TROUGHING ENDS UP DEEPENING ACROSS CENTRAL CANADA BY
LATE SUNDAY DUE TO RIDGING BUILDING UP INTO BRITISH COLUMBIA. AHEAD
OF THIS UPPER TROUGHING AND ASSOCIATED WITH THAT POTENT SHORTWAVE...
MODELS DEPICT A COLD FRONT. THIS FRONT LOOKS TO CROSS THE FORECAST
AREA SUNDAY NIGHT AT THE PRESENT TIME...WHICH IS WHEN THE TROUGHING
BEGINS TO DIG DOWN INTO THE NORTH CENTRAL U.S.. ANTICIPATING DRY
WEATHER UNTIL THIS FRONT PASSES...DUE TO THE DRY AIRMASS AHEAD OF
IT. WITH 850MB TEMPS RUNNING AROUND 8C ON SATURDAY AND 10-12C ON
SUNDAY...HIGH TEMPERATURES BOTH DAYS SHOULD BE ABLE TO TOP OUT IN
THE 70S. CHANGES ARE DEFINITELY ON THE WAY FOR MONDAY...THOUGH...AS
THE UPPER TROUGH APPROACHES THE AREA. LIKE TODAY THROUGH THURSDAY...
INDICATIONS ARE THAT A FRONTOGENETIC BAND OF PRECIPITATION WILL FORM
BEHIND THE COLD FRONT. HOW MUCH PRECIPITATION FORMS DEPENDS ON HOW
MUCH THE UPPER TROUGHING DIGS DOWN INTO THE NORTH CENTRAL U.S....
WHICH IS A LITTLE UNCERTAIN AT THIS TIME. THEREFORE...WILL BE
FOLLOWING THE CONSENSUS PRECIPITATION CHANCES OF 30-40 FOR MONDAY
AND MONDAY NIGHT. IF MODEL TRENDS CONTINUE...CHANCES ARE LIKELY
GOING TO BE RAISED IN LATER FORECASTS FOR MONDAY AND MONDAY NIGHT.
THE FORECAST FOR TUESDAY AND TUESDAY NIGHT ALSO RELY ON WHAT HAPPENS
WITH THE NORTH CENTRAL U.S. TROUGH. THE 12.00Z GFS FORMS A CLOSED
UPPER LOW OVER THE FORECAST AREA WHILE THE 11.12Z/12.00Z ECMWF KEEP
THE TROUGH PROGRESSIVE. THE FORMER SCENARIO YIELDS WET WHILE THE
LATTER SCENARIO SUGGESTS DRY...THOUGH BOTH ARE COOL AS 850MB TEMPS
TUMBLE TO A CHILLY 0-2C. 12.00Z GFS ENSEMBLES SUGGESTS BOTH THE GFS
AND ECMWF ARE POSSIBLE...THEREFORE 20-30 PERCENT CHANCES OF
PRECIPITATION ARE IN THE FORECAST. HIGHS TUESDAY WILL BE AT LEAST 15
DEGREES COLDER THAN THOSE ON SUNDAY...IF NOT MORE.
&&
.AVIATION...THROUGH 18Z THURSDAY
1241 PM CDT WED SEP 12 2012
THE MAIN FOCUS AT THE TAF SITES IS WITH THE OCCASIONAL RAIN
SHOWERS THROUGH TONIGHT ALONG WITH THE POTENTIAL FOR MVFR CEILINGS
THROUGH TONIGHT AND GUSTY WINDS THIS AFTERNOON. A COLD FRONT HAS
MOVED THROUGH LSE AND RST THIS MORNING LEAVING NORTHERLY WINDS IN
ITS WAKE. SCATTERED LIGHT RAIN SHOWERS WILL CONTINUE TO MOVE IN
FROM THE WEST THROUGH THE AFTERNOON AND EVENING HOURS AND BECOME
MORE WIDESPREAD AS THE DAY GOES ON. DUE TO DRY AIR IN THE LOW
LEVELS...VISIBILITY HAS BEEN GREATER THAN 6SM THROUGHOUT THE
REGION WITH CEILINGS HIGH AS WELL IN THE 6-10KFT RANGE. FORECAST
SOUNDINGS FOR RST AND LSE INDICATE THE SAME SHOULD HOLD ON FOR
TONIGHT...SO HAVE NOT PUT ANY MVFR INTO THE TAFS. FORECAST
GUIDANCE IS ALSO SUGGESTING THAT WINDS WILL RAPIDLY INCREASE THIS
AFTERNOON AS THE PRESSURE GRADIENT TIGHTENS ON THE NORTHERN SIDE
OF THE COLD FRONT. CONFIDENCE IS NOT HIGH WITH HOW HIGH THE GUSTS
WILL GET...SO HAVE AT LEAST STARTED A TREND TOWARD HIGHER WINDS
WITH GUSTS OF AROUND 25KT OCCURRING THIS AFTERNOON AND EARLY
EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
339 AM CDT WED SEP 12 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM....AJ
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1213 PM MDT WED SEP 12 2012
.UPDATE...
AVIATION...18Z TAF ISSUANCE...LIGHT RAIN LOOKS TO CONTINUE ACROSS
SOUTHERN PORTIONS OF THE NEBRASKA PANHANDLE THROUGH AROUND 20Z.
EXPECTING IFR CONDITIONS TO PERSIST AT KCYS...KSNY AND KBFF AS
WELL THROUGH THIS TIME...BUT WILL EVENTUALLY LIFT THROUGH THE LATE
AFTERNOON. ELSEWHERE...MVFR TO VFR CIGS WILL STEADILY LIFT THROUGH
THE AFTERNOON WITH GENERALLY LIGHT WINDS. A RETURN OF LOW MVFR TO
IFR VSBYS IS EXPECTED OVERNIGHT FROM KLAR EAST TO KCYS...KBFF AND
KSNY AS THE MIDLEVEL CLOUD DECK DEPARTS TO THE SOUTH AND
RADIATIONAL COOLING WITH RESIDUAL MOISTURE DEVELOPS PATCHY AREAS
OF FOG. WESTERLY SFC WINDS WILL DRY THINGS OUT COME MORNING...WITH
VFR CONDITIONS AND LIGHT WINDS EXPECTED FOR THURSDAY. RJM
&&
.PREV DISCUSSION... /ISSUED 1047 AM MDT WED SEP 12 2012/
UPDATE...
LIGHT RAIN ACTIVITY CONTINUES TO DECREASE AND IS MAINLY CONFINED
TO AREAS NEAR THE COLORADO BORDER. DO NOT THINK WE WILL SEE MUCH
CLEARING OF THE LOW CLOUDS OVER EXTREME SOUTHEAST WY AND THE
SOUTHERN NEBRASKA PANHANDLE WITH ABUNDANT LLVL MOISTURE FROM
RECENT RAINS AND LIGHT SE UPSLOPE IN PLACE. THE HRRR MODEL OUTPUT
SHOWS IFR CONDITIONS PERSISTING THROUGH THE ENTIRE AFTERNOON ALONG
AND JUST EAST OF THE SOUTHERN LARAMIE RANGE. HIGHS WILL BE QUITE
COOL TODAY WITH THE PERSISTENT LOW CLOUDS.
PREV DISCUSSION... /ISSUED 342 AM MDT WED SEP 12 2012/
SHORT TERM...TODAY THROUGH FRIDAY...
TODAY...WSR-88D REFLECTIVITY LOOP SHOWS LIGHT RAIN SOUTHEAST OF A
CHEYENNE TO CHADRON LINE. FOR THIS MORNING...THE NAM SHOWS THIS BAND
OF LIGHT RAIN PERSISTING...THUS HAVE CONTINUED WITH 50 TO 90 PERCENT
CHANCE OF RAIN THIS AREA. WITH TEMPERATURE AND DEWPOINT SPREADS
CLOSE...HAVE ALSO KEPT IN THE MENTION OF FOG THIS MORNING. THE CLOUD
SHIELD AND BAND OF RAIN WILL CONTINUE TO BE SQUEEZED TO OUR FAR
SOUTHERN COUNTIES THIS AFTERNOON...LIMITING WARM UP FROM CHEYENNE TO
SIDNEY. ELSEWHERE...CLEARING SKIES WILL PROMOTE WARMER TEMPERATURES.
TONIGHT...SURFACE HIGH PRESSURE MOVING OVERHEAD ALONG WITH CLEARING
SKIES WILL PROMOTE EXCELLENT RADIATION COOLING ALONG WITH AREAS OF
FOG EAST OF A LARAMIE TO LUSK LINE...DESPITE LIGHT WEST WINDS IN THE
LOW LEVELS.
THURSDAY...WARMING TREND ON TAP AS RIDGING ALOFT PREVAILS AND SUNNY
SKIES ABOUND. COOL NORTHEAST UPSLOPE WINDS WILL LIMIT WARMING
SOMEWHAT EAST OF INTERSTATE 25.
THURSDAY NIGHT...RETURN SOUTHERLY WINDS WILL LIMIT COOLING DESPITE
CLEAR SKIES.
FRIDAY...WARMING TREND CONTINUES WITH RETURN SOUTHERLY WINDS AND A
RIDGE ALOFT OVER THE SOUTHWEST AND ROCKY MOUNTAIN STATES.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...
THE 00Z MEDIUM RANGE MODEL SOLUTIONS ARE CONSISTENT DEPICTING A
PROGRESSIVE UPPER LEVEL PATTERN ACROSS THE LOWER 48. A BROAD RIDGE
OVER THE WESTERN HALF OF THE CONUS EARLY IN THE PERIOD WILL YIELD TO
A DIGGING TROUGH FROM CENTRAL CANADA INTO THE NORTH CENTRAL STATES
AS A RIDGE AMPLIFIES ALONG THE WEST COAST LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
SURFACE RIDGES WILL BE SITUATED WEST OF THE CONTINENTAL DIVIDE AND
EASTERN GREAT PLAINS...WITH A SURFACE TROUGH ALIGNED NORTH-SOUTH
OVER THE HIGH PLAINS THIS WEEKEND. DRY CONDITIONS WILL PREVAIL
FRIDAY NIGHT THROUGH SATURDAY NIGHT. SUNDAY MORNING...A CANADIAN
COLD FRONT WILL PROGRESS SMARTLY SOUTHWARD THROUGH MONTANA AND
THE DAKOTAS AND THROUGH WYOMING SUNDAY AFTERNOON. AHEAD OF THE
FRONT...A FEW SHOWERS OR TSTORMS MAY DEVELOP WEST OF THE LARAMIE
RANGE SUNDAY AFTERNOON. IT WILL BE BREEZY WITH WESTERLY WINDS
SHIFTING TO NORTHERLY IN THE WAKE OF THE FRONTAL PASSAGE. THE
SHOWER COVERAGE INCREASES IN THE POST-FRONTAL UPSLOPE FLOW PATTERN
SUNDAY NIGHT AND MONDAY MORNING. HOWEVER...QPF AMOUNTS WILL BE LIGHT.
THE SHOWERS WILL TAPER OFF FROM NORTHWEST TO SOUTHEAST MONDAY
AFTERNOON WITH A COOL SURFACE RIDGE BUILDING SOUTH ALONG THE
EASTERN WYOMING PLAINS AND NEBRASKA PANHANDLE. THE CENTER OF THE
RIDGE WILL BE CENTERED OVER THE CENTRAL GREAT PLAINS ON TUESDAY.
DOWNSLOPING WESTERLY FLOW AND 700MB TEMPERATURES 9 TO 12 DEG C
WILL EQUATE TO HIGHS IN THE 80S FOR THE PLAINS ON SATURDAY. HIGH
TEMPERATURES SUNDAY WILL OCCUR EARLY AFTERNOON OVER NORTHERN ZONES
AND LATER FOR SOUTHERN ZONES BASED ON THE TIMING OF THE FRONTAL
PASSAGE. IT WILL BE MUCH COOLER MONDAY WITH 700MB TEMPERATURES
FALLING TO -2 TO -6 DEG C WHICH WILL KEEP HIGH TEMPERATURES IN
THE 50S AND 60S. 700MB TEMPERATURES REBOUND TO 3 TO 7 DEG C
TUESDAY AFTERNOON. EXPECT NEAR AVERAGE HIGHS IN THE 70S LOWER
ELEVATIONS AND 50S AND 60S HIGHER ELEVATIONS.
FIRE WEATHER...
NO FIRE WEATHER CONCERNS TODAY DUE TO RELATIVELY HIGH HUMIDITIES.
MINIMUM HUMIDITIES WILL CONTINUE TO DECREASE THE NEXT SEVERAL DAYS
WITH NEAR CRITICAL HUMIDITIES OVER THE WEEKEND.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...FINCH
SHORT TERM/FIRE WEATHER...RUBIN
LONG TERM...JAMSKI
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1047 AM MDT WED SEP 12 2012
.UPDATE...
LIGHT RAIN ACTIVITY CONTINUES TO DECREASE AND IS MAINLY CONFINED
TO AREAS NEAR THE COLORADO BORDER. DO NOT THINK WE WILL SEE MUCH
CLEARING OF THE LOW CLOUDS OVER EXTREME SOUTHEAST WY AND THE
SOUTHERN NEBRASKA PANHANDLE WITH ABUNDANT LLVL MOISTURE FROM
RECENT RAINS AND LIGHT SE UPSLOPE IN PLACE. THE HRRR MODEL OUTPUT
SHOWS IFR CONDITIONS PERSISTING THROUGH THE ENTIRE AFTERNOON ALONG
AND JUST EAST OF THE SOUTHERN LARAMIE RANGE. HIGHS WILL BE QUITE
COOL TODAY WITH THE PERSISTENT LOW CLOUDS.
&&
.PREV DISCUSSION... /ISSUED 342 AM MDT WED SEP 12 2012/
SHORT TERM...TODAY THROUGH FRIDAY...
TODAY...WSR-88D REFLECTIVITY LOOP SHOWS LIGHT RAIN SOUTHEAST OF A
CHEYENNE TO CHADRON LINE. FOR THIS MORNING...THE NAM SHOWS THIS BAND
OF LIGHT RAIN PERSISTING...THUS HAVE CONTINUED WITH 50 TO 90 PERCENT
CHANCE OF RAIN THIS AREA. WITH TEMPERATURE AND DEWPOINT SPREADS
CLOSE...HAVE ALSO KEPT IN THE MENTION OF FOG THIS MORNING. THE CLOUD
SHIELD AND BAND OF RAIN WILL CONTINUE TO BE SQUEEZED TO OUR FAR
SOUTHERN COUNTIES THIS AFTERNOON...LIMITING WARM UP FROM CHEYENNE TO
SIDNEY. ELSEWHERE...CLEARING SKIES WILL PROMOTE WARMER TEMPERATURES.
TONIGHT...SURFACE HIGH PRESSURE MOVING OVERHEAD ALONG WITH CLEARING
SKIES WILL PROMOTE EXCELLENT RADIATION COOLING ALONG WITH AREAS OF
FOG EAST OF A LARAMIE TO LUSK LINE...DESPITE LIGHT WEST WINDS IN THE
LOW LEVELS.
THURSDAY...WARMING TREND ON TAP AS RIDGING ALOFT PREVAILS AND SUNNY
SKIES ABOUND. COOL NORTHEAST UPSLOPE WINDS WILL LIMIT WARMING
SOMEWHAT EAST OF INTERSTATE 25.
THURSDAY NIGHT...RETURN SOUTHERLY WINDS WILL LIMIT COOLING DESPITE
CLEAR SKIES.
FRIDAY...WARMING TREND CONTINUES WITH RETURN SOUTHERLY WINDS AND A
RIDGE ALOFT OVER THE SOUTHWEST AND ROCKY MOUNTAIN STATES.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...
THE 00Z MEDIUM RANGE MODEL SOLUTIONS ARE CONSISTENT DEPICTING A
PROGRESSIVE UPPER LEVEL PATTERN ACROSS THE LOWER 48. A BROAD RIDGE
OVER THE WESTERN HALF OF THE CONUS EARLY IN THE PERIOD WILL YIELD TO
A DIGGING TROUGH FROM CENTRAL CANADA INTO THE NORTH CENTRAL STATES
AS A RIDGE AMPLIFIES ALONG THE WEST COAST LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
SURFACE RIDGES WILL BE SITUATED WEST OF THE CONTINENTAL DIVIDE AND
EASTERN GREAT PLAINS...WITH A SURFACE TROUGH ALIGNED NORTH-SOUTH
OVER THE HIGH PLAINS THIS WEEKEND. DRY CONDITIONS WILL PREVAIL
FRIDAY NIGHT THROUGH SATURDAY NIGHT. SUNDAY MORNING...A CANADIAN
COLD FRONT WILL PROGRESS SMARTLY SOUTHWARD THROUGH MONTANA AND
THE DAKOTAS AND THROUGH WYOMING SUNDAY AFTERNOON. AHEAD OF THE
FRONT...A FEW SHOWERS OR TSTORMS MAY DEVELOP WEST OF THE LARAMIE
RANGE SUNDAY AFTERNOON. IT WILL BE BREEZY WITH WESTERLY WINDS
SHIFTING TO NORTHERLY IN THE WAKE OF THE FRONTAL PASSAGE. THE
SHOWER COVERAGE INCREASES IN THE POST-FRONTAL UPSLOPE FLOW PATTERN
SUNDAY NIGHT AND MONDAY MORNING. HOWEVER...QPF AMOUNTS WILL BE LIGHT.
THE SHOWERS WILL TAPER OFF FROM NORTHWEST TO SOUTHEAST MONDAY
AFTERNOON WITH A COOL SURFACE RIDGE BUILDING SOUTH ALONG THE
EASTERN WYOMING PLAINS AND NEBRASKA PANHANDLE. THE CENTER OF THE
RIDGE WILL BE CENTERED OVER THE CENTRAL GREAT PLAINS ON TUESDAY.
DOWNSLOPING WESTERLY FLOW AND 700MB TEMPERATURES 9 TO 12 DEG C
WILL EQUATE TO HIGHS IN THE 80S FOR THE PLAINS ON SATURDAY. HIGH
TEMPERATURES SUNDAY WILL OCCUR EARLY AFTERNOON OVER NORTHERN ZONES
AND LATER FOR SOUTHERN ZONES BASED ON THE TIMING OF THE FRONTAL
PASSAGE. IT WILL BE MUCH COOLER MONDAY WITH 700MB TEMPERATURES
FALLING TO -2 TO -6 DEG C WHICH WILL KEEP HIGH TEMPERATURES IN
THE 50S AND 60S. 700MB TEMPERATURES REBOUND TO 3 TO 7 DEG C
TUESDAY AFTERNOON. EXPECT NEAR AVERAGE HIGHS IN THE 70S LOWER
ELEVATIONS AND 50S AND 60S HIGHER ELEVATIONS.
AVIATION...12Z TAF ISSUANCE...
POST-FRONTAL NORTHEASTERLY UPSLOPE WINDS AND AMPLE MOISTURE WILL
PROMOTE MVFR TO IFR CEILINGS AND VISIBILITIES ALONG AND EAST OF A
LARAMIE TO SCOTTSBLUFF LINE THIS MORNING. SOME MVFR CEILINGS MAY
LINGER THROUGH MID AFTERNOON AT CHEYENNE...SIDNEY AND SCOTTSBLUFF
BEFORE IMPROVING TO VFR. SKIES WILL CLEAR THIS EVENING WITH LIGHT
SOUTHEASTERLY WINDS.
FIRE WEATHER...
NO FIRE WEATHER CONCERNS TODAY DUE TO RELATIVELY HIGH HUMIDITIES.
MINIMUM HUMIDITIES WILL CONTINUE TO DECREASE THE NEXT SEVERAL DAYS
WITH NEAR CRITICAL HUMIDITIES OVER THE WEEKEND.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
UPDATE...FINCH