Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/13/12
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
940 PM EDT WED SEP 12 2012
.UPDATE 2...
A TROUGH OF LOW PRESSURE WAS LOCATED OVER THE FLORIDA STRAITS
THIS EVENING WITH A MID TO UPPER LEVEL LOW DEVELOPING OVER THE
NORTHERN BAHAMA ISLANDS. HIGH PRESSURE WAS ALSO LOCATED OVER THE
MID ATLANTIC STATES THIS EVENING.
THE TROUGH WILL REMAIN NEARLY STATIONARY TONIGHT INTO
THURSDAY...AS THE MID TO UPPER LEVEL LOW MOVES WEST AND THROUGH
THE FLORIDA KEYS. THE HIGH WILL ALSO REMAIN OVER THE MID ATLANTIC
STATES THROUGH THURSDAY. THIS WILL KEEP THE BREEZY TO WINDY
NORTHEAST WINDS OVER THE CWA TONIGHT INTO THURSDAY. TROPICAL
MOISTURE WILL ALSO START TO WORK INTO THE EAST COAST METRO AREAS
TONIGHT FROM THE BAHAMA ISLANDS...BEFORE SPREADING WESTWARD
THROUGH REST OF THE CWA ON THURSDAY. SO HAVE INCREASED THE POPS
OVER THE EAST COAST METRO AREAS TO SCATTERED COVERAGE...AND THEN
UP THE POPS TO SCATTERED COVERAGE OVER ALL OF SOUTH FLORIDA FOR
THURSDAY.
THE SCA CONDITIONS WILL ALSO REMAIN IN EFFECT FOR ALL OF THE
ATLANTIC WATERS AND BISCAYNE BAY TONIGHT WITH SCEC FOR REST OF
SOUTH FLORIDA WATERS TONIGHT...DUE TO THE BREEZY TO WINDY EASTERLY
WINDS.
REST OF THE FORECAST LOOKS GOOD AT THIS TIME AND NO OTHER CHANGES
ARE PLANNED AT THIS TIME.
&&
.UPDATE...54/BNB
.PREV DISCUSSION... /ISSUED 804 PM EDT WED SEP 12 2012/
AVIATION...FOLLOWED LAMP GUIDANCE WHICH KEEPS WINDS UP THROUGH
THE NIGHT. HRRR ALSO SHOWS THIS. IT WILL BE BREEZY TOMORROW AS
WELL. CONTINUED VCSH ALL EAST COAST SITES AS SCATTERED SHOWERS
WILL CONTINUE TO MOVE ONSHORE. SLIGHT CHC OF TSRA. DIFFICULT TO
TIME, SO ONLY VCSH IS WARRANTED. DIRECT IMPACTS WOULD BE BRIEF AND
INCLUDE THE POTENTIAL FOR LIFR AND GUSTY WINDS TO AROUND 35
KT...BUT PROBABILITIES FAVOR VFR OR MVFR. /GREGORIA
&&
PREV DISCUSSION... /ISSUED 516 PM EDT WED SEP 12 2012/
UPDATE...
THE ASCAT SATELLITE PASS AROUND NOON TODAY WAS SHOWING WINDS
AROUND 20 KNOTS OVER THE ATLANTIC WATERS OF SOUTH FLORIDA. THE
WINDS LATE THIS AFTERNOON ALONG THE EAST COAST HAVE ALSO BEEN
AROUND 15 KNOTS WITH GUSTS UP TO 25 KNOTS. THESE WIND SPEEDS
SHOULD CONTINUE OVER THE EAST COAST METRO AREAS INCLUDING THE
ADJACENT COASTAL WATERS TONIGHT. SO WILL BE INCREASING THE WINDS
TO AROUND 20 KNOTS FOR THE ATLANTIC AND BISCAYNE BAY WATERS FOR
TONIGHT ALONG WITH UPGRADING THE SCEC TO THE SCA CONDITIONS FOR
THE ATLANTIC AND BISCAYNE BAY WATERS. REST OF THE FORECAST LOOKS
GOOD AT THIS TIME AND NO OTHER CHANGES ARE PLANNED AT THIS TIME.
&&
UDPATED...54/BNB
PREV DISCUSSION... /ISSUED 235 PM EDT WED SEP 12 2012/
DISCUSSION...
WATER VAPOR IMAGERY AND NAM ANALYSIS THIS AFTERNOON SHOWED HIGH
PRESSURE OVER THE EASTERN SEABOARD...WITH MODERATE EAST TO
NORTHEAST FLOW ACROSS THE REGION. A STALLED FRONTAL BOUNDARY OVER
THE FLORIDA STRAITS WILL DISSIPATE LATER TODAY. ONLY ISOLATED TO
WIDELY SCATTERED SHOWERS AND A COUPLE THUNDERSTORMS HAVE FORMED
THUS FAR ACROSS THE REGION. WITH THE SLIGHTLY DRIER AND WARMER AIR
ALOFT...ONLY EXPECT ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE AFTERNOON HOURS.
COASTAL CONVERGENCE OVERNIGHT WILL LIKELY LEAD TO SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS FOR THE EAST COAST
OVERNIGHT. WITH EASTERLY FLOW AND PWATS AROUND 2 INCHES CONTINUING
ACROSS THE REGION ON THURSDAY...EXPECT ANOTHER DAY OF SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS. HIGH PRESSURE WILL THEN BEGIN
TO MOVE OFF TO THE NORTHEAST AS A SHORTWAVE TROUGH MOVES INTO THE
GREAT LAKES. THE PRESSURE GRADIENT WILL WEAKEN AND MORE DIURNALLY
DRIVEN SHOWERS AND THUNDERSTORMS WILL BE EXPECTED...WITH THE BEST
CHANCE OF SHOWERS AND STORMS TOWARDS THE GULF COAST.
OVER THE WEEKEND...CONDITIONS WILL RETURN TO NORMAL FOR THIS TIME
OF YEAR WITH MAINLY AFTERNOON SHOWERS/TSTMS SETTING UP INLAND AND
WEST EACH DAY. EARLY TO THE MIDDLE OF 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...ESPECIALLY OVER THE NORTHERN HALF OF THE LOCAL AREA
AROUND THE LAKE REGION.
AVIATION...FOR 18Z TAFS.
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.
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 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 THE FLORIDA STRAITS WILL DISSIPATE LATER
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 THROUGH THURSDAY. THIS WILL PROVIDE
A BRISK NORTHEASTERLY WIND FLOW OVER SOUTH FLORIDA THROUGH
THURSDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS.
DISPERSION WILL BE GENERALLY GOOD MOST ZONES THURSDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 79 87 77 89 / 40 50 20 40
FORT LAUDERDALE 81 87 78 87 / 40 50 20 40
MIAMI 80 88 78 85 / 40 50 20 40
NAPLES 76 89 75 90 / 10 40 40 50
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK THROUGH THURSDAY EVENING FOR COASTAL
BROWARD-COASTAL MIAMI DADE-COASTAL PALM BEACH.
AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR BISCAYNE BAY-
COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT
20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH,
FL OUT 20 NM-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL
EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE
BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL
EXTENDING FROM 20 NM TO 60 NM.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS MIAMI FL
804 PM EDT WED SEP 12 2012
.AVIATION...FOLLOWED LAMP GUIDANCE WHICH KEEPS WINDS UP THROUGH
THE NIGHT. HRRR ALSO SHOWS THIS. IT WILL BE BREEZY TOMORROW AS
WELL. CONTINUED VCSH ALL EAST COAST SITES AS SCATTERED SHOWERS
WILL CONTINUE TO MOVE ONSHORE. SLIGHT CHC OF TSRA. DIFFICULT TO
TIME, SO ONLY VCSH IS WARRANTED. DIRECT IMPACTS WOULD BE BRIEF AND
INCLUDE THE POTENTIAL FOR LIFR AND GUSTY WINDS TO AROUND 35
KT...BUT PROBABILITIES FAVOR VFR OR MVFR. /GREGORIA
&&
.PREV DISCUSSION... /ISSUED 516 PM EDT WED SEP 12 2012/
UPDATE...
THE ASCAT SATELLITE PASS AROUND NOON TODAY WAS SHOWING WINDS
AROUND 20 KNOTS OVER THE ATLANTIC WATERS OF SOUTH FLORIDA. THE
WINDS LATE THIS AFTERNOON ALONG THE EAST COAST HAVE ALSO BEEN
AROUND 15 KNOTS WITH GUSTS UP TO 25 KNOTS. THESE WIND SPEEDS
SHOULD CONTINUE OVER THE EAST COAST METRO AREAS INCLUDING THE
ADJACENT COASTAL WATERS TONIGHT. SO WILL BE INCREASING THE WINDS
TO AROUND 20 KNOTS FOR THE ATLANTIC AND BISCAYNE BAY WATERS FOR
TONIGHT ALONG WITH UPGRADING THE SCEC TO THE SCA CONDITIONS FOR
THE ATLANTIC AND BISCAYNE BAY WATERS. REST OF THE FORECAST LOOKS
GOOD AT THIS TIME AND NO OTHER CHANGES ARE PLANNED AT THIS TIME.
UDPATED...54/BNB
PREV DISCUSSION... /ISSUED 235 PM EDT WED SEP 12 2012/
DISCUSSION...
WATER VAPOR IMAGERY AND NAM ANALYSIS THIS AFTERNOON SHOWED HIGH
PRESSURE OVER THE EASTERN SEABOARD...WITH MODERATE EAST TO
NORTHEAST FLOW ACROSS THE REGION. A STALLED FRONTAL BOUNDARY OVER
THE FLORIDA STRAITS WILL DISSIPATE LATER TODAY. ONLY ISOLATED TO
WIDELY SCATTERED SHOWERS AND A COUPLE THUNDERSTORMS HAVE FORMED
THUS FAR ACROSS THE REGION. WITH THE SLIGHTLY DRIER AND WARMER AIR
ALOFT...ONLY EXPECT ISOLATED TO SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE AFTERNOON HOURS.
COASTAL CONVERGENCE OVERNIGHT WILL LIKELY LEAD TO SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS FOR THE EAST COAST
OVERNIGHT. WITH EASTERLY FLOW AND PWATS AROUND 2 INCHES CONTINUING
ACROSS THE REGION ON THURSDAY...EXPECT ANOTHER DAY OF SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS. HIGH PRESSURE WILL THEN BEGIN
TO MOVE OFF TO THE NORTHEAST AS A SHORTWAVE TROUGH MOVES INTO THE
GREAT LAKES. THE PRESSURE GRADIENT WILL WEAKEN AND MORE DIURNALLY
DRIVEN SHOWERS AND THUNDERSTORMS WILL BE EXPECTED...WITH THE BEST
CHANCE OF SHOWERS AND STORMS TOWARDS THE GULF COAST.
OVER THE WEEKEND...CONDITIONS WILL RETURN TO NORMAL FOR THIS TIME
OF YEAR WITH MAINLY AFTERNOON SHOWERS/TSTMS SETTING UP INLAND AND
WEST EACH DAY. EARLY TO THE MIDDLE OF 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...ESPECIALLY OVER THE NORTHERN HALF OF THE LOCAL AREA
AROUND THE LAKE REGION.
AVIATION...FOR 18Z TAFS.
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.
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 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 THE FLORIDA STRAITS WILL DISSIPATE LATER
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 THROUGH THURSDAY. THIS WILL PROVIDE
A BRISK NORTHEASTERLY WIND FLOW OVER SOUTH FLORIDA THROUGH
THURSDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS.
DISPERSION WILL BE GENERALLY GOOD MOST ZONES THURSDAY.
&&
.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...HIGH RIP CURRENT RISK THROUGH THURSDAY EVENING FOR COASTAL
BROWARD-COASTAL MIAMI DADE-COASTAL PALM BEACH.
AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR BISCAYNE BAY-
COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT
20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH,
FL OUT 20 NM-WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL
EXTENDING FROM 20 NM TO THE TERRITORIAL WATERS OF THE
BAHAMAS-WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL
EXTENDING FROM 20 NM TO 60 NM.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
935 AM EDT TUE SEP 11 2012
.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE THROUGH THURSDAY. DRY WEATHER ALONG
WITH SLIGHTLY COOLER THAN NORMAL TEMPERATURES WILL CONTINUE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
DRY HIGH PRESSURE IS RIDGING INTO THE FORECAST AREA FROM THE
NORTH. AN AREA OF MID-LEVEL CLOUDINESS COVERS THE NORTHWEST PART
OF THE FORECAST AREA. THIS MOISTURE IS TRAPPED UNDER A STRONG
INVERSION AND IS BEING SUPPORTED BY LIFT ASSOCIATED WITH A MID-
LEVEL SHORTWAVE TROUGH. THE RAP SHOWS THIS MOISTURE TENDING TO
SHIFT SOUTH AND WEST THIS AFTERNOON. ALSO EXPECT HEATING AND MIXING
WILL RESULT IN BREAKS IN THE CLOUDINESS. STILL...THE CLOUDINESS
SHOULD LIMIT THE TEMPERATURE RISE IN THE NORTHWEST PART AND WE
HAVE LOWED THE HIGH TEMPERATURE FORECAST A FEW DEGREES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
AN UPPER-LEVEL RIDGE WILL BUILD INTO THE REGION WITH SURFACE HIGH
PRESSURE EXTENDING FROM THE MID-ATLANTIC THROUGH THE CAROLINAS TO
THE GULF COAST. WE CAN EXPECT MOSTLY CLEAR SKIES WITH NORTHEAST TO
EAST WINDS. AFTERNOON HUMIDITIES WILL BE LOW. THE TEMPERATURE
GUIDANCE WAS CLOSE. WE SHOULD SEE AFTERNOON HIGHS IN THE MID 80S
AND NIGHTTIME LOWS IN THE MID 50S TO AROUND 60.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE MODELS CONTINUE IN GOOD AGREEMENT WITH HIGH PRESSURE AND DRY
AIR DOMINATING THE REGION THROUGH THURSDAY NIGHT. 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 GFS ENSEMBLE MEANS
SUPPORT POPS OF 20 TO 30 PERCENT.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
SATELLITE SHOWS SOME MID LEVEL CLOUDS THIS MORNING ACROSS THE
UPSTATE AND NORTHERN MIDLANDS. THESE CLOUDS HAVE BEGUN TO DRIFT
SOUTHWARD AND WILL IMPACT CAE/CUB DURING THE MORNING HOURS.
OTHERWISE...EXPECT VFR CONDITIONS EXPECTED THROUGH THE 24 HOUR TAF
PERIOD. HIGH PRESSURE CENTERED TO OUR NORTH WILL MAINTAIN A DRY
ATMOSPHERE. EXPECT SOME SCATTERED CLOUDS THROUGH THE DAY WITH LIGHT
EAST WINDS.
EXTENDED AVIATION OUTLOOK...NO IMPACTS TO AVIATION EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
938 PM CDT WED SEP 12 2012
.UPDATE...
STRONG COLD FRONT CONTINUES TO SURGE SOUTHEAST ACROSS THE FORECAST
AREA...QUITE A BIT FASTER THAN OPERATIONAL MODEL PROGS. FELT HRRR
AND RUC13 HAD THE BEST HANDLE ON THE SHORT-TERM TRENDS.
INITIAL ROUND OF SHOWERS/THUNDERSTORMS CURRENTLY EXITING OVER
EAST-CENTRAL KANSAS IS ASSOCIATED WITH THE SURFACE-850MB PORTION
OF THE COLD FRONT. THE MORE EXPANSIVE AREA OF PRECIPITATION WILL
CONTINUE TO SLOWLY TRANSITION SOUTHEAST INTO CENTRAL AND
EVENTUALLY SOUTH-CENTRAL KS AS THE NIGHT PROGRESSES. INSTABILITY
IS LACKING...SO NOT ANTICIPATING WIDESPREAD HEAVY RAIN...ALTHOUGH
ISOLATED LOCATIONS COULD APPROACH ONE-HALF INCH THROUGH SUNRISE.
WIDESPREAD RAINFALL AMOUNTS OF ONE/TWO-TENTHS OF AN INCH SEEMS
REASONABLE OVERNIGHT.
EXPECTING RAIN TO CONTINUE SHIFTING SLOWLY SOUTH THROUGH THE DAY
THURSDAY...AFFECTING SOUTH-CENTRAL/SOUTHEAST KS ALL DAY. LATEST
NAM IS NOW HINTING AT MID-LEVEL BAROCLINIC ZONE LINGERING A BIT
LONGER...WHICH COULD RESULT IN WIDESPREAD RAIN LINGERING OVER
SOUTHERN KANSAS THROUGH THURSDAY NIGHT.
ADK
&&
.PREV DISCUSSION... /ISSUED 649 PM CDT WED SEP 12 2012/
AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
WIDESPREAD RAIN/SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS WILL
GRADUALLY INCREASE FROM THE NORTHWEST THIS EVENING THROUGH TONIGHT
FOR ALL SITES EXCEPT KCNU...AS A STRONG COLD FRONT SURGES SOUTH
AND AN ASSOCIATED UPPER LEVEL TROUGH APPROACHES FROM THE
NORTHWEST. THUNDER CHANCES WILL BE GREATEST THIS EVENING FOR
KHUT-KSLN. STRONG/GUSTY NORTH WINDS WILL PREVAIL IMMEDIATELY
BEHIND THE COLD FRONT AS IT SURGES SOUTHEAST. ADDITIONALLY...CIGS
SHOULD GO MVFR BELOW 2000 FT AGL FOR ALL SITES EXCEPT KCNU
TONIGHT...WITH SCATTERED IFR CIGS FOR MAINLY KRSL-KSLN-KHUT.
ADK
PREV DISCUSSION... /ISSUED 318 PM CDT WED SEP 12 2012/
DISCUSSION...
MAIN FORECAST CHALLENGES ARE THE TIMING OF THE COLD FRONTAL PASSAGE
TONIGHT AND THE ASSOCIATED PRECIPITATION TONIGHT AND TOMORROW.
SYNOPSIS:
THE UPPER TROUGH AXIS IS SITUATED ACROSS THE INTER-MOUNTAIN WEST AND
IS SWINGING SOUTHEASTWARD TOWARD THE CENTRAL PLAINS. THIS WAVE WILL
BE THE MAIN WEATHER PRODUCER FOR THE NEXT FEW DAYS. THE SURFACE LOW
AND ASSOCIATED FRONT IS MOVING ACROSS THE CENTRAL PLAINS. IT HAS
SLOWED/STALLED OUT ACROSS CENTRAL KANSAS THIS MORNING/AFTERNOON.
THE WIND SHIFT IS JUST KNOCKING ON KRSL`S DOOR AS OF 3PM. SCATTERED
LIGHT SHOWERS THIS MORNING MOVED OFF TO THE NORTHEAST LEAVING MOSTLY
CLEAR SKIES...THAT IN COMBINATION WITH STOUT SOUTHERLY WINDS HAVE
ALLOWED TEMPS TO RISE INTO THE LOW TO MID 90S ACROSS MUCH OF THE
AREA...EXCEPT NEAREST THE FRONT. HOWEVER...SCATTERED MID-LEVEL
CLOUDS HAVE BEGUN TO DEVELOP OUT AHEAD OF THE SURFACE FRONT AND WILL
BE THE CONCERN FOR THIS AFTERNOON/EARLY EVENING.
TONIGHT - THURSDAY:
THE LATEST HIGHER RESOLUTION MODEL GUIDANCE (NAM/HRRR/RUC) CONTINUES
TO INDICATE SHOWER/THUNDERSTORM DEVELOPMENT AHEAD OF AND WITH THE
FRONT AS IT MOVES SOUTHWARD THIS EVENING. HAVE CUT BACK ON POPS
THROUGH 03Z THURSDAY OVER CENTRAL KANSAS...AND INCREASE IT GREATLY
FROM 03Z ON THROUGH THE NIGHT. INSTABILITY IS MARGINAL...BUT
INCREASES IN THE WARM SECTOR TOWARDS 00Z THURSDAY. SEVERE
THUNDERSTORMS ARE NOT EXPECTED...BUT SOME STRONGER STORMS COULD
DEVELOP IN THE MODEST CAPE/MINIMAL SHEAR REGION AHEAD OF THE FRONT.
THE MAIN CONCERN WILL BE ISOLATED STRONG WIND GUSTS. AS DRY AIR
FILTERS IN...INSTABILITY WILL BE ALL BUT SQUASHED.
THE FRONT IS EXPECTED TO MOVE SOUTHEAST FROM KRSL TO KICT AROUND
03-05Z AND THEN ON TO KCNU BY 10-12Z. HIGH PRESSURE HAS BUILT IN
BEHIND THE FRONT...INCREASING THE PRESSURE GRADIENT. AS THE FRONT
MOVES THROUGH WINDS WILL FLIRT WITH THE 30MPH WIND ADVISORY
CRITERIA. OBSERVING DAYTIME TRENDS...WINDS APPROACHED 30MPH...BUT DID
NOT EXCEED FOR LONG PERIODS OF TIME. REGARDLESS IT WILL BE WINDY
OUT OF THE NORTHEAST OVERNIGHT.
POST FRONTAL PRECIPITATION WILL CONTINUE THROUGH THE DAY THURSDAY
ENDING FROM NORTHWEST TO SOUTHEAST BY THURSDAY AFTERNOON.
WIDESPREAD PRECIPITATION ACCUMULATIONS OF 0.5 INCH TO 1 INCH ARE
EXPECTED WITH SOME AREAS SEEING HIGHER AMOUNTS. TEMPERATURES WILL
BE SIGNIFICANTLY COOLER BEHIND THE FRONT THURSDAY WITH AREAS UNDER
CLOUD COVER AND PRECIPITATION NOT MAKING IT OUT OF THE 60S. WHERE
THE SUN BREAKS OUT TEMPS WILL IMPROVE TO THE LOW 70S.
FRIDAY - SUNDAY:
THE WAVE THAT MOVES THROUGH WILL LEAVE BEHIND SOME ENERGY THAT WILL
MOVE IN FROM THE FOUR CORNERS REGION...TX/OK PANHANDLES AND WILL
IMPACT THE FORECAST INTO THE WEEKEND. IN ADDITION TO THE COOL
AIRMASS BEHIND THE FRONT...THIS ADDITIONAL SYSTEM WILL KEEP OKLAHOMA
AND PORTIONS OF SOUTHERN KANSAS CLOUDY AND COOL. TEMPS WILL BE IN
THE 70S WITH SOME AREAS POSSIBLY COOLER. THE LIFT ASSOCIATED WITH
THIS PV ANOMALY WILL ALSO KEEP PRECIPITATION CHANCES FOR SOUTHERN
KANSAS THROUGH FRIDAY AND SATURDAY. CONFIDENCE IS NOT HIGH ON HOW
EXPANSIVE THIS PRECIP WILL BE.
MONDAY - WEDNESDAY:
THE NEXT MAIN SHORTWAVE WILL KICK THE ENERGY EASTWARD THAT WILL
IMPACT THE REGION OVER THE WEEKEND. THIS WAVE WILL AGAIN PUSH A
FRONT THROUGH THE AREA WITH ADDITIONAL PRECIPITATION CHANCES FOR
EARLY NEXT WEEK. THIS FRONT IS NOT QUITE AS POTENT AND HAS MUCH
LESS MOISTURE TO WORK WITH THAN THE SYSTEM FOR TONIGHT/THURSDAY.
SHOWERS/THUNDERSTORMS ARE POSSIBLE...BUT CONFIDENCE IS LACKING ON
HOW WIDESPREAD THE RAIN WILL BE FOR THE AREA. TEMPERATURES FOR THE
NEXT WORKWEEK WILL BE IN THE 70S AND LOW 80S...SEASONAL FOR MID
SEPTEMBER.
BILLINGS
AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
FOCUS IS ON THE TIMING OF THE FRONT AND ASSOCIATED PRECIPITATION/
CEILINGS. THERE IS GOOD AGREEMENT IN SHORT RANGE MODELS FOR SOME
RAIN SHOWERS/THUNDERSTORMS TO BREAK OUT AHEAD OF THE FRONT FROM
MID LEVEL DECK...WHICH WILL BE CLOSE TO KHUT/KSLN AND LIKELY CATCH
KICT LATER THIS AFTERNOON. THE MAIN SHOW WILL OCCUR TONIGHT WITH
PRECIPITATION CHANCES INCREASING AT MOST SITES DURING THE NIGHT
AND LINGERING INTO THE MORNING. ANTICIPATE MVFR CEILINGS TO OCCUR
IN THE VICINITY OF MORE WIDESPREAD RAIN. VERY GUSTY NORTH WINDS
ARE EXPECTED JUST BEHIND THE FRONT. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 57 64 51 74 / 50 70 30 10
HUTCHINSON 56 62 46 74 / 90 80 10 10
NEWTON 56 64 48 73 / 60 80 20 10
ELDORADO 56 65 51 75 / 40 80 30 10
WINFIELD-KWLD 59 68 54 74 / 30 90 50 20
RUSSELL 53 69 43 75 / 100 50 10 10
GREAT BEND 53 66 44 73 / 100 70 10 10
SALINA 54 66 45 75 / 100 70 10 10
MCPHERSON 55 63 46 74 / 90 70 10 10
COFFEYVILLE 62 75 55 77 / 10 50 50 30
CHANUTE 61 69 54 75 / 20 70 40 20
IOLA 60 68 54 74 / 20 70 30 20
PARSONS-KPPF 62 72 55 76 / 10 50 50 30
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
315 PM CDT TUE SEP 11 2012
...UPDATED SHORT TERM 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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 104 PM CDT TUE SEP 11 2012
VFR SKY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH MIDDAY
WEDNESDAY...SO WINDS WILL BE THE PRIMARY AVIATION INTEREST. FOR THE
REMAINDER OF THIS AFTERNOON...25 KNOT WINDS CAN BE EXPECTED FROM THE
SOUTH WITH SOME GUSTS IN THE 30-35 KNOT RANGE. AFTER SUNSET...WINDS
WILL DECREASE SOME...BUT 20 KNOTS SUSTAINED WILL LIKELY PERSIST
THROUGH A GOOD PORTION OF THE NIGHT. AN INTENSE LOW LEVEL JET WILL
DEVELOP AND PEAK AROUND 2000 FEET ABOVE GROUND LEVEL AT 55 TO 60
KNOTS...SO WILL GO AHEAD AND CONTINUE THE INCLUSION OF A WS GROUP
FOR DDC AND HYS TERMINALS. WINDS WILL DECREASE TO 10 TO 15 KNOTS 12
TO 18Z AS GRADIENT RELAXES SOME PRIOR TO STRONG COLD FRONT PASSAGE
AROUND MIDDAY WEDNESDAY.
&&
.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...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
243 PM CDT TUE SEP 11 2012
...UPDATE TO LONG TERM...
.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...(TODAY THROUGH TONIGHT)
ISSUED AT 144 AM CDT TUE SEP 11 2012
THE SURFACE LOW PRESSURE SYSTEM OVER EASTERN COLORADO WILL DEEPEN
DURING THE DAY TODAY, CAUSING WARM AIR TO RIDE NORTH-NORTHEAST ACROSS
WESTERN KANSAS. WINDS WILL BE SOUTH TODAY, INCREASING INTO THE 15
TO 25 MPH GUSTING TO 35 MPH RANGE THIS AFTERNOON. THE BIGGEST WEATHER
DECISION TODAY IS DEW POINTS. THINK WITH WHAT HAPPENED YESTERDAY
WITH DRIER AIR MIXING DOWN AFTER THE STRONG WINDS KICKED IN, HAVE
DECIDED TO ISSUE A RED FLAG WARNING FOR ABOUT OUR EASTERN HALF OF
THE CWA, FROM 2PM TO 8PM CDT. THE WINDS WILL BE STRONGEST THERE,
THESE STRONG WINDS WILL HELP MIX DOWN DRIER AIR, AND RELATIVE
HUMIDITIES SHOULD DIP TO THE 14-16 PERCENT RANGE DURING THE AFTERNOON.
IN OUR WESTERN CWA, DUE TO THE PROXIMITY TO THE EASTERN COLORADO
LOW, WINDS WILL NOT BE AS STRONG AS THEY WILL BE IN THE EAST, AND
DEW POINTS SHOULD DIP AS MUCH BECAUSE OF LESS DOWNWARD MIXING.
MAX TEMPERATURES TODAY WILL PEAK IN THE MID 90S MOST PLACES, THE
WARMEST IN OUR SOUTHWESTERN CORNER. WINDS WILL BE SLOW TO ABATE
TONIGHT, WITH THE COLORADO LOW MOVING INTO WESTERN KANSAS. WINDS
MAY NOT DROP TO LESS THAN 20 MPH UNTIL AFTER 06Z, AND THEN ONLY TO
10 TO 12 MPH. WITH CLEAR SKIES, BUT THE PERSISTENT WINDS, MIN
TEMPERATURES WILL ONLY DROP TO MID TO UPPER 60S. AT THIS TIME,
STILL THINK PRECIP WILL HOLD OFF UNTIL AFTER MY TUESDAY 12Z TIME
FRAME. ALL SHORT TERM MODEL CONCUR ON NO PRECIP IN OUR CWA UNTIL
AFTER 12Z TUESDAY.
.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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 104 PM CDT TUE SEP 11 2012
VFR SKY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH MIDDAY
WEDNESDAY...SO WINDS WILL BE THE PRIMARY AVIATION INTEREST. FOR THE
REMAINDER OF THIS AFTERNOON...25 KNOT WINDS CAN BE EXPECTED FROM THE
SOUTH WITH SOME GUSTS IN THE 30-35 KNOT RANGE. AFTER SUNSET...WINDS
WILL DECREASE SOME...BUT 20 KNOTS SUSTAINED WILL LIKELY PERSIST
THROUGH A GOOD PORTION OF THE NIGHT. AN INTENSE LOW LEVEL JET WILL
DEVELOP AND PEAK AROUND 2000 FEET ABOVE GROUND LEVEL AT 55 TO 60
KNOTS...SO WILL GO AHEAD AND CONTINUE THE INCLUSION OF A WS GROUP
FOR DDC AND HYS TERMINALS. WINDS WILL DECREASE TO 10 TO 15 KNOTS 12
TO 18Z AS GRADIENT RELAXES SOME PRIOR TO STRONG COLD FRONT PASSAGE
AROUND MIDDAY WEDNESDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 67 94 55 65 / 10 20 80 80
GCK 64 89 52 67 / 10 20 80 60
EHA 65 87 52 66 / 10 20 80 70
LBL 66 93 53 66 / 10 20 70 70
HYS 66 88 53 67 / 10 10 70 50
P28 67 95 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...BURKE
LONG TERM...JJOHNSON
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
106 PM CDT TUE SEP 11 2012
...UPDATED SYNOPSIS AND AVIATION SECTIONS...
.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...(TODAY THROUGH TONIGHT)
ISSUED AT 144 AM CDT TUE SEP 11 2012
THE SURFACE LOW PRESSURE SYSTEM OVER EASTERN COLORADO WILL DEEPEN
DURING THE DAY TODAY, CAUSING WARM AIR TO RIDE NORTH-NORTHEAST ACROSS
WESTERN KANSAS. WINDS WILL BE SOUTH TODAY, INCREASING INTO THE 15
TO 25 MPH GUSTING TO 35 MPH RANGE THIS AFTERNOON. THE BIGGEST WEATHER
DECISION TODAY IS DEW POINTS. THINK WITH WHAT HAPPENED YESTERDAY
WITH DRIER AIR MIXING DOWN AFTER THE STRONG WINDS KICKED IN, HAVE
DECIDED TO ISSUE A RED FLAG WARNING FOR ABOUT OUR EASTERN HALF OF
THE CWA, FROM 2PM TO 8PM CDT. THE WINDS WILL BE STRONGEST THERE,
THESE STRONG WINDS WILL HELP MIX DOWN DRIER AIR, AND RELATIVE
HUMIDITIES SHOULD DIP TO THE 14-16 PERCENT RANGE DURING THE AFTERNOON.
IN OUR WESTERN CWA, DUE TO THE PROXIMITY TO THE EASTERN COLORADO
LOW, WINDS WILL NOT BE AS STRONG AS THEY WILL BE IN THE EAST, AND
DEW POINTS SHOULD DIP AS MUCH BECAUSE OF LESS DOWNWARD MIXING.
MAX TEMPERATURES TODAY WILL PEAK IN THE MID 90S MOST PLACES, THE
WARMEST IN OUR SOUTHWESTERN CORNER. WINDS WILL BE SLOW TO ABATE
TONIGHT, WITH THE COLORADO LOW MOVING INTO WESTERN KANSAS. WINDS
MAY NOT DROP TO LESS THAN 20 MPH UNTIL AFTER 06Z, AND THEN ONLY TO
10 TO 12 MPH. WITH CLEAR SKIES, BUT THE PERSISTENT WINDS, MIN
TEMPERATURES WILL ONLY DROP TO MID TO UPPER 60S. AT THIS TIME,
STILL THINK PRECIP WILL HOLD OFF UNTIL AFTER MY TUESDAY 12Z TIME
FRAME. ALL SHORT TERM MODEL CONCUR ON NO PRECIP IN OUR CWA UNTIL
AFTER 12Z TUESDAY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 415 AM CDT TUE SEP 11 2012
THE MEDIUM RANGE MODELS CONTINUE TO SHOW A STRONG WAVE MOVING ACROSS
SOUTHERN CANADA AND THE NORTHERN TIER OF STATES TUESDAY NIGHT AND
WEDNESDAY WITH A SECONDARY TROUGH DEVELOPING ACROSS THE NORTHERN
PLAINS WEDNESDAY AND PUSHING SOUTHEAST THROUGH THE MIDWEST AND
CENTRAL PLAINS ON THURSDAY. THE MEDIUM RANGE MODELS ARE COMING INTO
MUCH BETTER AGREEMENT REGARDING THE STRENGTH AND TIMING OF THIS
SYSTEM. THE ASSOCIATED SURFACE COLD FRONT IS FORECAST TO MOVE SLOWLY
INTO WEST CENTRAL AND NORTHWEST KANSAS DURING THE MORNING HOURS
WEDNESDAY BEFORE ACCELERATING SOUTHEAST LATER IN THE DAY WITH THE
APPROACH OF THE DIGGING UPPER WAVE. THROUGH WEDNESDAY NIGHT AND
THURSDAY THE UPPER WAVE MOVES INTO THE REGION. AHEAD OF THE WAVE
THERE WILL BE A FAIRLY SIGNIFICANT UPPER LEVEL JET EXTENDING FROM
THE CENTRAL HIGH PLAINS INTO THE WESTERN GREAT LAKES. MUCH OF THE
REGION WILL BE UNDER THE RIGHT ENTRANCE REGION OF THIS JET WEDNESDAY
NIGHT INTO THURSDAY MORNING.
THE BEST CHANCES FOR PRECIPITATION ACROSS WESTERN KANSAS WILL BE
LATE WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING AS THE MID LEVELS
OF THE ATMOSPHERE COOL AND MOISTEN UP IN RESPONSE TO THE APPROACHING
WAVE. MODEL SOUNDINGS SHOW SOME WEAK INSTABILITY WEDNESDAY AFTERNOON
WITH ONLY A FEW HUNDRED J/KG OF CAPE. THIS SHOULD SUPPORT A FEW
THUNDERSTORMS ALONG THE FRONT. PRECIPITATION CHANCES WILL BE
INCREASING CONSIDERABLY WEDNESDAY NIGHT GIVEN THE SATURATED SOUNDING
PROFILE AND UPWARD VERTICAL MOTION ASSOCIATED WITH THE WAVE AND
UPPER JET. HAVE BUMPED UP POPS TO NEAR 80 PERCENT DURING THE
WEDNESDAY NIGHT THROUGH THURSDAY MORNING TIME PERIOD. ALONG WITH
SURROUNDING WFOS...HAVE ALSO BUMPED UP THE QPF VALUES THROUGH THIS
TIME PERIOD CLOSER TO THE HPC FORECAST.
PRECIPITATION CHANCES WILL BE DIMINISHING FROM NORTHWEST TO
SOUTHEAST ON THURSDAY AS THE UPPER WAVE MOVES BY. THINK THAT BY
THURSDAY EVENING ONLY SLIGHT CHANCE POPS WILL BE WARRANTED OVER
SOUTH CENTRAL KANSAS WITH CHANCES ENDING AFTER MIDNIGHT.
SOUTHWEST KANSAS WILL SEE A FEW MILD AND DRY DAYS INTO THE WEEKEND
AS UPPER LEVEL SHORTWAVE RIDGING MOVES OVER THE CENTRAL HIGH PLAINS.
ANOTHER STRONG SHORTWAVE TROUGH IS PROGGED BY THE MODELS TO DIVE
INTO THE MIDWEST AND PLAINS NEXT MONDAY. THE MODELS SHOW WIDELY
VARYING SOLUTIONS AS TO HOW THIS PANS OUT. FOR NOW WILL LEAVE THE
ALLBLEND FORECAST AS IS WHICH HAS SMALL POPS OVER WEST CENTRAL
KANSAS ON MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 104 PM CDT TUE SEP 11 2012
VFR SKY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH MIDDAY
WEDNESDAY...SO WINDS WILL BE THE PRIMARY AVIATION INTEREST. FOR THE
REMAINDER OF THIS AFTERNOON...25 KNOT WINDS CAN BE EXPECTED FROM THE
SOUTH WITH SOME GUSTS IN THE 30-35 KNOT RANGE. AFTER SUNSET...WINDS
WILL DECREASE SOME...BUT 20 KNOTS SUSTAINED WILL LIKELY PERSIST
THROUGH A GOOD PORTION OF THE NIGHT. AN INTENSE LOW LEVEL JET WILL
DEVELOP AND PEAK AROUND 2000 FEET ABOVE GROUND LEVEL AT 55 TO 60
KNOTS...SO WILL GO AHEAD AND CONTINUE THE INCLUSION OF A WS GROUP
FOR DDC AND HYS TERMINALS. WINDS WILL DECREASE TO 10 TO 15 KNOTS 12
TO 18Z AS GRADIENT RELAXES SOME PRIOR TO STRONG COLD FRONT PASSAGE
AROUND MIDDAY WEDNESDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 67 94 55 66 / 10 20 80 70
GCK 64 89 52 65 / 10 30 80 60
EHA 65 87 52 65 / 10 40 80 60
LBL 66 93 53 66 / 10 20 80 60
HYS 66 88 53 65 / 10 20 80 60
P28 67 95 63 70 / 10 10 60 60
&&
.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...BURKE
LONG TERM...GERARD
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
313 PM EDT TUE SEP 11 2012
.SYNOPSIS...
HIGH PRESSURE WILL ALLOW FOR A DRY WEEK WITH TEMPERATURES WARMING
EACH DAY. A COLD FRONT WILL CROSS THE AREA LATE IN THE WEEK INTO
THE EARLY WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THAT THE UPPER OHIO
VALLEY IS ON THE NORTHEASTERN PERIPHERY OF A BROAD 500MB TROUGH
CENTERED ACROSS THE MISSOURI VALLEY AND THE GULF STATES. AT THE
SURFACE, A 1028MB HIGH IS CENTERED ACROSS WEST VIRGINIA AND IS
DOMINATING THE WEATHER PATTERN ACROSS THE EASTERN US WITH CLEAR
SKIES.
HIGH PRESSURE AND A DEEP LAYER OF DRY AIR ALOFT WILL CONTINUE TO
DOMINATE THE PATTERN THROUGH TONIGHT. ASIDE FROM LITTLE CIRRUS
PASSING NORTH OF THE AREA, SKIES WILL BE CLEAR WITH LIGHT
SOUTHERLY WINDS. TEMPS WILL RECOVER QUICKLY TODAY WITH HIGHS
CLOSE TO A MAV/MET BLEND IN THE MID 70S ACROSS MOST OF THE AREA.
ANOTHER NIGHT OF RADIATIONAL COOLING WITH PATCHY RIVER VALLEY FOG
CAN BE EXPECTED TONIGHT WITH LOWS AROUND 5 TO 10 DEGREES BELOW
SEASONAL NORMALS.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE MID-LEVEL RIDGE WILL BUILD
INTO THE UPPER OHIO VALLEY ON WEDNESDAY AND THEN AMPLIFY FURTHER
INTO THE NORTHEAST ON THURSDAY AND FRIDAY. THIS WILL ALLOW FOR
BENIGN WEATHER TO CONTINUE, WITH CLEAR SKIES ASIDE FROM OCCASIONAL
PASSING CIRRUS.
TEMPERATURES THROUGH THIS PERIOD WILL BE INCREASINGLY WARMER
WEDNESDAY INTO THURSDAY WITH WARM AIR ADVECTION IN A SOUTHWESTERLY
FLOW. HIGHS WEDNESDAY WILL BE AROUND 5 DEGREES ABOVE NORMAL,
MODERATING TO 10 DEGREES ABOVE NORMAL ON THURSDAY. ON FRIDAY,
DESPITE INCREASING CLOUD COVERAGE AHEAD OF A COLD FRONT, ENHANCED
WARM AIR ADVECTION AHEAD OF THE FRONT WILL ALLOW TEMPS TO WARM TO
5 TO 10 DEGREES ABOVE NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
SOME UNCERTAINTY ENTERS THE FORECAST ON FRIDAY NIGHT AS A MID-
LEVEL TROUGH ACROSS THE UPPER MIDWEST CLOSED OFF INTO A LOW OVER
THE GREAT LAKES AND SWEEPS A COLD FRONT ACROSS THE REGION. THE 12Z
GFS IS FASTER WITH THE FRONTAL PASSAGE (FRIDAY NIGHT) THAN THE
ECMWF/CANADIAN SOLUTIONS (SATURDAY). HAVE TRENDED EARLIER WITH THE
FRONTAL PASSAGE FRIDAY NIGHT INTO EARLY SATURDAY, WITH CHANCE POPS
AND SCHC THUNDER.
THE CLOSED LOW WILL PUSH INTO THE NORTHEAST ON SUNDAY, LEAVING THE
UPPER OHIO VALLEY IN A NORTHWESTERLY FLOW. EARLY NEXT WEEK,
UNCERTAINTY INCREASES AS MODELS DIVERGE AND THUS FORECAST IS
CLOSE TO HPC. TEMPS WILL BE NEAR NORMAL SEASONAL VALUES THROUGH
THE EXTENDED PERIOD.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
HIGH PRESSURE WILL PROVIDE FOR VFR CONDITIONS AND LIGHT WINDS
THROUGH THE TAF PERIOD. A BRIEF PERIOD OF VISIBILITY RESTRICTIONS
WILL BE POSSIBLE WITH RIVER VALLEY FOG NEAR DAWN AT KAGC.
.OUTLOOK /WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE WILL MAINTAIN VFR CONDITIONS THROUGH FRIDAY WITH
ONLY BRIEF RESTRICTIONS IN VALLEY FOG POSSIBLE IN THE MORNING EACH
DAY. A FRONT APPROACHING FOR THE WEEKEND COULD POTENTIALLY BRING
SHOWERS FRIDAY NIGHT INTO SATURDAY. VFR CONDITIONS WILL RETURN IN
THE WAKE OF THE FRONT ON SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
109 PM EDT TUE SEP 11 2012
.SYNOPSIS...
HIGH PRESSURE WILL MAINTAIN DRY WEATHER WITH WARMING TEMPERATURES
EACH DAY THIS WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO MAKE
SLIGHT ADJUSTMENT TO SKY GRIDS AS CIRRUS CROSSES PORTIONS OF THE
AREA. THE REST OF THE PREVIOUS DISCUSSION REMAINS THE SAME.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THAT THE UPPER OHIO
VALLEY IS ON THE NORTHEASTERN PERIPHERY OF A BROAD 500MB TROUGH
CENTERED ACROSS THE MISSOURI VALLEY AND THE GULF STATES. AT THE
SURFACE, A 1028MB HIGH IS CENTERED ACROSS WEST VIRGINIA AND IS
DOMINATING THE WEATHER PATTERN ACROSS THE EASTERN US WITH CLEAR
SKIES.
HIGH PRESSURE AND A DEEP LAYER OF DRY AIR ALOFT WILL CONTINUE TO
DOMINATE THE PATTERN THROUGH TONIGHT. ASIDE FROM LITTLE CIRRUS
PASSING NORTH OF THE AREA, SKIES WILL BE CLEAR WITH LIGHT
SOUTHERLY WINDS. TEMPS WILL RECOVER QUICKLY TODAY WITH HIGHS
CLOSE TO A MAV/MET BLEND IN THE MID 70S ACROSS MOST OF THE AREA.
ANOTHER NIGHT OF RADIATIONAL COOLING WITH PATCHY RIVER VALLEY FOG
CAN BE EXPECTED TONIGHT WITH LOWS AROUND 5 TO 10 DEGREES BELOW
SEASONAL NORMALS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
MIDWRN RIDGE ALOFT IS FORECAST TO SHIFT EWD AND AMPLIFY IN RESPONSE
TO CUTOFF LOW DIGGING ACRS WRN CANADA. WITH THE SFC HIGHS EWD
SHIFT...WARM ADVCTN WL RESUME UNDR THE SBSDNC REGIME/RISING HTS
ALOFT. TEMP MODERATION MAY THUS BE ANTICIPATED WITH AFTN HIGHS
RISING TO APPROX 5 DEGREES ABOVE THE SEASONAL AVERAGES.
STRNG RADIATIONAL COOLING WL AGAIN SPPRT SUB NORMAL LOWS ON
WEDNESDAY MRNG...BUT NR AVG READINGS ARE ANTICIPATED FOR THURSDAY
AND FRIDAY MRNG AS THE BNDRY LYR MSTR SLOWLY RISES. OVERALL TEMP
FORECAST WAS BASED ON PERSISTENCE WITH A TWEAK BASED ON RECENT GFS
AND NAM MOS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
ALTHOUGH MDLS RMN IN GENL AGRMNT THAT A CDFTN WL MOV ACRS THE UPR
OH VALLEY OVR THE WEEKEND...TIMING IS QNABLE AS IS NORMAL AT THIS
POINT IN THE FORECAST CYCLE. THE GFS CONTS TO BE THE FASTER
SOLN...WITH THE FRONT AFFECTING THE REGION SATURDAY/SATURDAY
NIGHT. AS THE ENSEMBLE MEAN LEANS MORE TWDS A SATURDAY NGT/SUNDAY
PASSAGE...HAVE GONE WITH THIS SCENARIO. HIGH PRES IS THEN FORECAST
TO SLIDE OVR THE AREA BY SUNDAY.
TEMPS WERE FORECASTED ABOVE THE AVERAGES FOR FRIDAY...THEN DROPPED TO
NR SEASONAL READINGS IN THE WAKE OF THE FRONT.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL PROVIDE FOR VFR CONDITIONS AND LIGHT WINDS
THROUGH THE TAF PERIOD.
.OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL MAINTAIN VFR CONDITIONS THROUGH FRIDAY WITH
ONLY BRIEF RESTRICTIONS IN VALLEY FOG POSSIBLE IN THE MORNING EACH
DAY. A FRONT APPROACHING FOR THE WEEKEND COULD POTENTIALLY BRING
SHOWERS ON SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1041 AM EDT TUE SEP 11 2012
.SYNOPSIS...
HIGH PRESSURE WILL MAINTAIN DRY WEATHER WITH WARMING TEMPERATURES
EACH DAY THIS WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
15Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO REMOVE
MORNING FOG WORDING AND TO LOWER HIGHS BY A DEGREE BASED ON
RECENT TEMP TRENDS. OTHERWISE, FORECAST REMAINS UNCHANGED.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THAT THE UPPER OHIO
VALLEY IS ON THE NORTHEASTERN PERIPHERY OF A BROAD 500MB TROUGH
CENTERED ACROSS THE MISSOURI VALLEY AND THE GULF STATES. AT THE
SURFACE, A 1028MB HIGH IS CENTERED ACROSS WEST VIRGINIA AND IS
DOMINATING THE WEATHER PATTERN ACROSS THE EASTERN US WITH CLEAR
SKIES.
HIGH PRESSURE AND A DEEP LAYER OF DRY AIR ALOFT WILL CONTINUE TO
DOMINATE THE PATTERN THROUGH TONIGHT. ASIDE FROM LITTLE CIRRUS
PASSING NORTH OF THE AREA, SKIES WILL BE CLEAR WITH LIGHT
SOUTHERLY WINDS. TEMPS WILL RECOVER QUICKLY TODAY WITH HIGHS
CLOSE TO A MAV/MET BLEND IN THE MID 70S ACROSS MOST OF THE AREA.
ANOTHER NIGHT OF RADIATIONAL COOLING WITH PATCHY RIVER VALLEY FOG
CAN BE EXPECTED TONIGHT WITH LOWS AROUND 5 TO 10 DEGREES BELOW
SEASONAL NORMALS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
MIDWRN RIDGE ALOFT IS FORECAST TO SHIFT EWD AND AMPLIFY IN RESPONSE
TO CUTOFF LOW DIGGING ACRS WRN CANADA. WITH THE SFC HIGHS EWD
SHIFT...WARM ADVCTN WL RESUME UNDR THE SBSDNC REGIME/RISING HTS
ALOFT. TEMP MODERATION MAY THUS BE ANTICIPATED WITH AFTN HIGHS
RISING TO APPROX 5 DEGREES ABOVE THE SEASONAL AVERAGES.
STRNG RADIATIONAL COOLING WL AGAIN SPPRT SUB NORMAL LOWS ON
WEDNESDAY MRNG...BUT NR AVG READINGS ARE ANTICIPATED FOR THURSDAY
AND FRIDAY MRNG AS THE BNDRY LYR MSTR SLOWLY RISES. OVERALL TEMP
FORECAST WAS BASED ON PERSISTENCE WITH A TWEAK BASED ON RECENT GFS
AND NAM MOS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
ALTHOUGH MDLS RMN IN GENL AGRMNT THAT A CDFTN WL MOV ACRS THE UPR
OH VALLEY OVR THE WEEKEND...TIMING IS QNABLE AS IS NORMAL AT THIS
POINT IN THE FORECAST CYCLE. THE GFS CONTS TO BE THE FASTER
SOLN...WITH THE FRONT AFFECTING THE REGION SATURDAY/SATURDAY
NIGHT. AS THE ENSEMBLE MEAN LEANS MORE TWDS A SATURDAY NGT/SUNDAY
PASSAGE...HAVE GONE WITH THIS SCENARIO. HIGH PRES IS THEN FORECAST
TO SLIDE OVR THE AREA BY SUNDAY.
TEMPS WERE FORECASTED ABOVE THE AVERAGES FOR FRIDAY...THEN DROPPED TO
NR SEASONAL READINGS IN THE WAKE OF THE FRONT.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL PROVIDE FOR VFR CONDITIONS AND LIGHT WINDS
THROUGH THE TAF PERIOD.
.OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL MAINTAIN VFR CONDITIONS THROUGH FRIDAY WITH
ONLY BRIEF RESTRICTIONS IN VALLEY FOG POSSIBLE IN THE MORNING EACH
DAY. A FRONT APPROACHING FOR THE WEEKEND COULD POTENTIALLY BRING
SHOWERS ON SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
809 AM EDT TUE SEP 11 2012
.SYNOPSIS...
HIGH PRESSURE WILL MAINTAIN DRY WEATHER WITH WARMING TEMPERATURES THIS
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
12Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED WITH
LITTLE CHANGE TO THE FORECAST OTHER THAN TO ACCOUNT FOR THE LATEST
TRENDS IN TEMP AND DEW POINT.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES THAT THE UPPER OHIO
VALLEY IS ON THE NORTHEASTERN PERIPHERY OF A BROAD 500MB TROUGH
CENTERED ACROSS THE MISSOURI VALLEY AND THE GULF STATES. AT THE
SURFACE, A 1028MB HIGH IS CENTERED ACROSS WEST VIRGINIA AND IS
DOMINATING THE WEATHER PATTERN ACROSS THE EASTERN US WITH CLEAR
SKIES. WITH COOL TEMPS THIS MORNING DROPPING INTO THE UPPER 30S
IN SOME LOCATIONS, THIS HAS ALLOWED FOR PATCHY DENSE FOG TO
DEVELOP IN THE WARMER RIVER VALLEYS.
HIGH PRESSURE AND A DEEP LAYER OF DRY AIR ALOFT WILL CONTINUE TO
DOMINATE THE PATTERN THROUGH TONIGHT. ASIDE FROM LITTLE CIRRUS
PASSING NORTH OF THE AREA, SKIES WILL BE CLEAR WITH LIGHT
SOUTHERLY WINDS. TEMPS WILL RECOVER QUICKLY TODAY AS PATCHY FOG
BURNS OFF, WITH HIGHS CLOSE TO A MAV/MET BLEND IN THE MID TO
UPPER 70S ACROSS THE AREA. ANOTHER NIGHT OF RADIATIONAL COOLING
CAN BE EXPECTED TONIGHT WITH LOWS AROUND 5 TO 10 DEGREES BELOW
SEASONAL NORMALS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
MIDWRN RIDGE ALOFT IS FORECAST TO SHIFT EWD AND AMPLIFY IN RESPONSE
TO CUTOFF LOW DIGGING ACRS WRN CANADA. WITH THE SFC HIGHS EWD
SHIFT...WARM ADVCTN WL RESUME UNDR THE SBSDNC REGIME/RISING HTS
ALOFT. TEMP MODERATION MAY THUS BE ANTICIPATED WITH AFTN HIGHS
RISING TO APPROX 5 DEGREES ABOVE THE SEASONAL AVERAGES.
STRNG RADIATIONAL COOLING WL AGAIN SPPRT SUB NORMAL LOWS ON
WEDNESDAY MRNG...BUT NR AVG READINGS ARE ANTICIPATED FOR THURSDAY
AND FRIDAY MRNG AS THE BNDRY LYR MSTR SLOWLY RISES. OVERALL TEMP
FORECAST WAS BASED ON PERSISTENCE WITH A TWEAK BASED ON RECENT GFS
AND NAM MOS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
ALTHOUGH MDLS RMN IN GENL AGRMNT THAT A CDFTN WL MOV ACRS THE UPR
OH VALLEY OVR THE WEEKEND...TIMING IS QNABLE AS IS NORMAL AT THIS
POINT IN THE FORECAST CYCLE. THE GFS CONTS TO BE THE FASTER
SOLN...WITH THE FRONT AFFECTING THE REGION SATURDAY/SATURDAY
NIGHT. AS THE ENSEMBLE MEAN LEANS MORE TWDS A SATURDAY NGT/SUNDAY
PASSAGE...HAVE GONE WITH THIS SCENARIO. HIGH PRES IS THEN FORECAST
TO SLIDE OVR THE AREA BY SUNDAY.
TEMPS WERE FORECASTED ABOVE THE AVERAGES FOR FRIDAY...THEN DROPPED TO
NR SEASONAL READINGS IN THE WAKE OF THE FRONT.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
CALM WINDS AND CLEAR SKIES ARE PROVIDING FOR OPTIMAL RADIATIONAL
COOLING. WITH VERY LOW DEWPOINTS...DO NOT THINK THERE WILL BE MUCH
IN THE WAY OF FOG OUTSIDE OF THE RIVER VALLEY LOCATIONS. AS THIS FOG
LIFTS NEAR SUNRISE...THERE COULD BE A BRIEF PERIOD OF MVFR/IFR VSBYS
AT KDUJ/KMGW/KHLG AS WAS THE CASE YESTERDAY. OTHERWISE...HIGH
PRESSURE WILL PROVIDE FOR VFR CONDITIONS AND LIGHT WINDS THROUGH THE
REST OF THE PERIOD.
.OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE WILL MAINTAIN VFR CONDITIONS THROUGH FRIDAY WITH ONLY
BRIEF RESTRICTIONS IN VALLEY FOG POSSIBLE IN THE MORNING EACH DAY.
A FRONT APPROACHING FOR THE WEEKEND COULD POTENTIALLY BRING SHOWERS
ON SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
940 PM CDT WED SEP 12 2012
.UPDATE...
ISSUED AT 930 PM CDT WED SEP 12 2012
CURRENT FORECAST LOOKS PRETTY MUCH ON TRACK FOR THE REST OF THE
NIGHT. COLD FRONT IS NOW STRETCHING FROM NEAR DAVENPORT IA
SOUTHWEST TO JUST NORTH OF THE KC METRO AREA. CURRENT RAP FORECAST
HAS IT PUSHING THROUGH KIRKSVILLE AROUND 09Z AND DOWN TO ALONG A
COLUMBIA MO-QUINCY IL LINE BY 12Z. NEW NAM AGREES WITH THIS
POSITION...THO THE TRUE LOW LEVEL BAROCLINICITY LAGS BACK IN
NORTHWEST/NORTH CENTRAL MISSOURI AT 12Z. STILL THINK THE AREA WILL
REMAIN DRY AT LEAST UNTIL THEN...POTENTIALLY INTO MID MORNING
THURSDAY. CURRENT TEMPERATURES ARE WITHIN 1 TO 2 DEGREES OF
FORECAST...SO TEMP TRENDS LOOK ON TRACK AT THIS TIME.
CARNEY
&&
.SHORT TERM...
ISSUED AT 208 PM CDT WED SEP 12 2012
(TONIGHT)
COLD FRONT CURRENTLY STRETCHING FROM SOUTHEAST NEBRASKA TO EASTERN
WISCONSIN WILL CONTINUE TO SLOWLY EDGE ITS WAY SOUTH TONIGHT AND
BE KNOCKING ON THE FAR NORTHERN PORTION OF THE CWA BY 12Z. RAIN
CONTINUES TO BE POST FRONTAL WITH THIS SYSTEM...SO THE FORECAST
REMAINS DRY OVERNIGHT. SOUTHERLY WIND AND INCREASING LOW LEVEL
MOISTURE SHOULD KEEP TEMPERATURES SLIGHTLY ABOVE NORMAL...WITH A
NOD GOING TO THE WARMER MET GUIDANCE.
CVKING
&&
.LONG TERM...
ISSUED AT 344 PM CDT WED SEP 12 2012
(THURSDAY THROUGH WEDNESDAY)
COLD FRONT WILL BE OVER NORTHERN PORTIONS OF FORECAST AREA BY
DAYBREAK THURSDAY MORNING...WITH SHOWERS SPREADING INTO THE
REGION...MAINLY POST FRONTAL. BEST CHANCES WILL BE OVER NORTHEAST
MO/WEST CENTRAL IL DURING THE DAY ON THURSDAY...THEN INCREASE IN
COVERAGE ACROSS REST OF FORECAST AREA THURSDAY EVENING. NOT A LOT OF
INSTABILITY WITH THIS SYSTEM...SO SHOULD BE MOSTLY RAIN/SHOWERS...
THOUGH SOME ISOLATED STORMS NOT OUT OF THE QUESTION FOR CENTRAL MO
THURSDAY AFTERNOON...SO LEFT MENTION IN THERE. MODELS CONTINUE TO BE
A LOT FASTER WITH ENDING THE PCPN...SO HAVE LOWERED POPS AFTER 06Z
FRIDAY AND HAVE PCPN COMING TO AN END AT ALL LOCATIONS BY 18Z FRIDAY.
AS FOR HIGHS ON THURSDAY...WILL BE DEPENDENT ON CLOUD COVER AND PCPN
COVERAGE. FOR NOW SHOULD SEE HIGHS RANGING FROM THE UPPER 60S FAR
NORTH TO THE LOW 80S ALONG AND SOUTH OF I-70. ALSO...WILL BE GOING
WITH A NON DIURNAL TREND...MAINLY FOR NORTHERN PORTIONS OF FORECAST
AREA...WITH HIGH TEMPS IN THE LATE MORNING HOURS...THEN TEMPS STEADY
OR SLOWLY FALLING DURING THE AFTERNOON HOURS.
BY THURSDAY NIGHT...COLDER AIR TO BEGIN FILTERING IN WITH LOWS IN
THE MID 40S TO MID 50S.
WILL SEE MORE FALL LIKE WEATHER ONCE AGAIN THROUGH THE WEEKEND.
HIGHS ON FRIDAY WILL BE IN THE LOW 70S AND IN THE MID 70S ON
SATURDAY. AS FOR LOW TEMPS...WILL SEE ANOTHER COLD NIGHT FRIDAY
NIGHT WITH LOWS IN THE UPPER 40S TO LOW 50S.
STRONG SURFACE RIDGE TO BEGIN MOVING OFF TO THE EAST LATE IN THE
WEEKEND AND INTO EARLY NEXT WEEK WITH TEMPS MODERATING A BIT. HIGHS
WILL BE IN THE UPPER 70S SUNDAY AND MONDAY.
THEN ANOTHER STRONG COLD FRONT TO MOVE INTO THE REGION ON
MONDAY...BRINGING ANOTHER CHANCE FOR SHOWERS AND THUNDERSTORMS
MONDAY AND MONDAY NIGHT. BEHIND THE SYSTEM...COOLER THAN NORMAL
WEATHER TO PERSIST WITH HIGHS IN THE MID 60S TO MID 70S WITH LOWS IN
THE MID 40S BY TUESDAY MORNING.
BYRD
&&
.AVIATION...
ISSUED AT 655 PM CDT WED SEP 12 2012
VFR CONDITIONS AND LIGHT S FLOW WILL CONTINUE AREAWIDE...AHEAD OF
THE CDFNT...WHICH IS CURRENTLY FROM SERN IA TO NWRN MO. CDFNT WILL
PUSH TO NEAR A KUIN-KCOU AXIS BETWEEN 10-13Z AND THEN PUSH INTO
THE STL METRO AREA BETWEEN 17-21Z. MODELS HAVE BACKED OFF ON PCPN
POTENTIAL WITH THIS...AS MUCH OF THE UPPER LEVEL SUPPORT MISSES US
TO THE N...LEAVING BEHIND WHAT WILL LIKELY BE A REGION OF SCT-NMRS
SHRA BEHIND THE CDFNT. INDICATIONS ARE INCREASING OF POTENTIAL FOR
NON-VFR CIGS BEHIND THE FRONT...AND HAVE ADDED IN SOME MVFR BUT
KEPT ABOVE 2KFT FOR NOW. LO CIGS SHOULD CLEAR OUT EARLY THURSDAY
EVENING FOR KUIN-KCOU AND LATER THURSDAY NIGHT FOR STL METRO.
SPECIFICS FOR KSTL...VFR AHEAD OF THE CDFNT UNTIL MID MORNING
THURSDAY...INCREASING LO VFR CIGS AHEAD OF CDFNT LATE THURSDAY
MORNING...THEN DROP TO MVFR CIGS BEHIND CD FROPA AROUND 18Z. PCPN
LOOKS SPOTTY...AND KEPT VCSH MENTION FOR NOW.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
810 PM CDT WED SEP 12 2012
.UPDATE...
SHOWERS HAVE MOVED JUST EAST OF THE FORECAST AREA. HAVE ENDED
PRECIPITATION AND LOWERED POPS. TEMPERATURE FORECAST LOOKS TO BE
ON TRACK IF SKIES CLEAR LATER.
&&
.PREV DISCUSSION... /ISSUED 647 PM CDT WED SEP 12 2012/
AVIATION...
SOME ISOLATED SHOWERS OVER THE NEBRASKA PANHANDLE THIS EVENING
WILL DISSIPATE WITH THE SETTING OF THE SUN. THE MAIN AREA OF
PRECIPITATION IS MOVING INTO CENTRAL NEBRASKA AND IS GENERALLY
EAST OF A KONL TO KIML LINE AND MOVING SLOWLY EAST. MVFR CEILINGS
OVER SOUTHWEST NEBRASKA WILL RISE INTO VFR CATEGORIES AFTER 1303Z.
SKIES CLEARING OUT OVER WESTERN NEBRASKA AFTER 1306Z WITH LIGHT
WINDS AND CLEAR SKIES THURSDAY UNDER SURFACE HIGH PRESSURE.
PREV DISCUSSION... /ISSUED 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.
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...POWER/CDC
AVIATION...POWER
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
647 PM CDT WED SEP 12 2012
.AVIATION...
SOME ISOLATED SHOWERS OVER THE NEBRASKA PANHANDLE THIS EVENING
WILL DISSIPATE WITH THE SETTING OF THE SUN. THE MAIN AREA OF
PRECIPITATION IS MOVING INTO CENTRAL NEBRASKA AND IS GENERALLY
EAST OF A KONL TO KIML LINE AND MOVING SLOWLY EAST. MVFR CEILINGS
OVER SOUTHWEST NEBRASKA WILL RISE INTO VFR CATEGORIES AFTER 1303Z.
SKIES CLEARING OUT OVER WESTERN NEBRASKA AFTER 1306Z WITH LIGHT
WINDS AND CLEAR SKIES THURSDAY UNDER SURFACE HIGH PRESSURE.
&&
.PREV DISCUSSION... /ISSUED 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.
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...POWER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1049 PM EDT WED SEP 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER THROUGH THE
END OF THE WORK WEEK. A WEAK AND MOISTURE STARVED COLD FRONT WILL
MOVE ACROSS THE AREA EARLY SATURDAY...THEN DISSIPATE ALTOGETHER
DURING SUNDAY. HIGH PRESSURE RIDGING FROM THE NE STATES WILL
DOMINATE THE WEATHER THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 1035 PM WEDNESDAY...CENTER OF SURFACE HIGH PRESSURE TO TRACK
OFFSHORE FROM THE MID-ATLANTIC AND NE STATES OVERNIGHT INTO
THURSDAY. LATEST SAT IMAGERY INDICATES THIN TO OCCASIONALLY OPAQUE
CIRRUS TO OVERSPREAD THE FA FROM THE SW DURING THE OVERNIGHT.
AT THE SAME TIME...EXTRAPOLATION OF THE SC DECK NEARSHORE AND
OFFSHORE FROM THE CAROLINAS USING THE LATEST IR SAT IMAGERY AS THE
INITIAL TIME...WILL MOVE PARTIALLY ONSHORE SOUTH OF THE SC/NC BORDER.
LATEST HRRR MODEL OUTPUT ILLUSTRATES POSSIBLE PCPN ACCOMPANYING
THE SC DECK AS IT REACHES AND MOVES ACROSS THE COASTAL WATERS SOUTH OF
THE NC-SC BORDER. AT THIS POINT...THE DRY AIR ACROSS LAND
LOCATIONS WITHIN THE FA...AND THE SUBSIDENCE ALOFT SHOULD HELP TO
PREVENT THE PCPN FROM MOVING ONSHORE AND INLAND. CURRENT MIN
FORECAST LOOKS ON CUE AND SEE NO REASON TO DETOUR FROM PREVIOUS
THINKING.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...HIGH PRESSURE RIDGING BACK FROM CENTER
SHIFTING FURTHER EAST INTO THE ATLANTIC OFF THE NEW ENGLAND COAST
ON THURS INTO EARLY FRI. THIS WILL CONTINUE TO PRODUCE AN E-NE ON
SHORE FLOW. BY FRIDAY...THE HIGH WEAKENS AS IT GETS SQUEEZED OUT
BY A MOISTURE STARVED COLD FRONT MOVING INTO THE CAROLINAS FROM
THE NORTHWEST. THE ON SHORE FLOW MAY PRODUCE SOME PATCHES OF
CLOUDS MOVING IN FROM THE WATERS OVERNIGHT THURS. THE MODELS SHOW
PCP WATER DOWN LESS THAN AN INCH THROUGH THURS AFTN BUT THEN AN
INCREASE WITH THIS ON SHORE FLOW AND APPROACHING COLD FRONT LATE
FRI INTO SAT.
THE MID TO UPPER RIDGE SLIPS OFF THE EAST COAST BY FRIDAY AS
TROUGH DEEPENS DOWN THROUGH THE APPALACHIANS. THIS WILL PRODUCE A
RETURN FLOW VERY BRIEFLY ON FRI. BOTH THE NAM AND GFS SHOW VERY
LITTLE UPPER LEVEL FORCING WITH THIS SYSTEM WITH BEST ENERGY
COMING IN THROUGH THE MID LEVELS AS SHORTWAVE CROSSES THE AREA
THROUGH FRI AFTN INTO THE EVENING. DURING THIS TIME SHOULD SEE
INCREASED CLDS IN E-NE FLOW AT LOW LEVELS AND PASSING UPPER LEVEL
CLOUDS. THE MOISTURE PROFILES SHOW AN INCREASE IN RH UP GREATER
THAN 90 PERCENT ABOVE H5 BUT VERY DRY AIR REMAINING IN THE MID
LEVELS. THEREFORE EXPECT LIMITED...IF ANY CHC OF SHALLOW PASSING
SHWRS.
BY END OF PERIOD A DEEP NW FLOW WILL SET UP IN THE MID LEVELS AS H5
TROUGH PUSHES FARTHER EAST. THE MAIN EFFECT OF THE FRONT WILL BE
INCREASED CLOUDS FRI AND A REINFORCEMENT AND SHIFT TO MORE
NORTHERLY WINDS FRI INTO SAT WITH ONLY A SLIGHT CHC OF PCP FRI.
TEMPERATURES NEAR CLIMO THROUGH THE PERIOD...MID 80S AND MID 60S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...SPLIT FLOW PATTERN DEVELOPS AT THE START OF
THE PERIOD AS A NORTHERN STREAM TROUGH DRIVES A COLD FRONT TOWARDS
THE EASTERN CAROLINAS. THIS FRONT DIVES INTO A RELATIVELY DRY AIR
MASS...AND MID/UPPER FORCING ASSOCIATED WITH IT IS QUITE WEAK.
THEREFORE...EXPECT VERY LITTLE IN THE WAY OF PRECIP WITH ITS
PASSAGE...AND INSTEAD WILL JUST SEE AN INCREASE IN CLOUD COVER. AS
WINDS TURN MORE E/NE BEHIND THE FRONT...THIS ADVECTS ATLANTIC
MOISTURE INTO THE COLUMN. INHERITED FORECAST SHOWS SCHC POP FOR THE
WKND...AND WILL LEAVE THIS UNCHANGED. HOWEVER...FORECAST PROFILES
SHOW MUCH DRIER AIR ABOVE 750MB OR SO THAN WAS PREDICTED YESTERDAY
SINCE THE ATLANTIC FETCH REMAINS CONFINED TO THE LOWER PART OF THE
COLUMN. IF THIS TREND CONTINUES...MAY HAVE TO REMOVE ALL MENTION OF
TSTMS...ESPECIALLY ON SATURDAY. TEMPS WILL BE RIGHT AROUND CLIMO
DURING THE WKND.
SOUTHERN STREAM VORT ALONG THE GULF COAST WILL THEN ROTATE NORTHEAST
ON LEE SIDE OF DEVELOPING LONGWAVE TROUGH ACROSS THE PLAINS. AT THE
SAME TIME...DEEP SE FLOW DEVELOPS AND IT APPEARS THAT LATE MON/TUE
WILL BE THE BEST CHANCE FOR RAINFALL DURING THE EXTENDED. A SURFACE
REFLECTION TO THIS MID-LEVEL IMPULSE MAY WORK JUST WEST OF THE
CWA...WHICH ALLOWS FOR THE WARM FRONT AND ITS ASSOCIATED LIFT TO
CROSS US LATE MONDAY. STILL DIFFERENCES IN STRENGTH OF THIS FEATURE
FROM THE MODELS...SO WILL KEEP LOW-CHC POP FOR NOW. WILL NOTE THAT
IF THE ECMWF IS CORRECT THIS COULD END UP BEING A ROBUST RAINFALL
EVENT...BUT WITH GUIDANCE FLIPPING IN ITS AMPLIFICATION OF CENTRAL
5H TROUGH...WILL KEEP ONLY LIMITED QPF FOR NOW. BY WEDNESDAY THIS
FEATURE WILL BE WELL NE OF THE AREA AND DRYING WILL OCCUR.
TEMPS FOR THE FIRST HALF OF NEXT WEEK WILL BE AROUND CLIMO FOR
HIGHS...BUT LOWS WILL BE A FEW DEGREES ABOVE EACH NIGHT DUE TO
INCREASED SOUTHERLY FLOW AND CLOUD COVER.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AS OF 00Z...EXPECT VFR THROUGH THE VALID PERIOD...WITH EXCEPTION OF
POTENTIAL FOR SHORT-LIVED MVFR DUE TO FOG AT KLBT BEFORE SUNRISE.
NORTHEAST WINDS WILL BECOME LIGHT OVERNIGHT...WITH A FEW LINGERING
LOW TO MID LEVEL CLOUDS ACROSS THE AREA. GIVEN GUIDANCE AND FCST
SOUNDINGS...CANNOT RULE OUT FOG AT KLBT BEFORE DAYBREAK...THOUGH
CONFIDENCE IS LOWERED. AS A RESULT...HAVE OPTED TO INTRODUCE TEMPO
IN CURRENT FCST. AFTER SUNRISE...EAST- NORTHEAST WINDS WILL
INCREASE TO AOB 10 KTS FOR THE REMAINDER OF THE DAY. INCREASING
MOISTURE...ESPECIALLY ALONG THE COAST...WILL ALLOW FOR LOW CLOUDS
TO DEVELOP EARLY ON IN THE DAY. COVERAGE WILL BE FEW/SCT...THOUGH
DO NOT ANTICIPATE ANY RESTRICTIONS TO ARISE.
THE EXTENDED OUTLOOK THROUGH MONDAY...POTENTIAL FOR BRIEF REDUCED
VSBYS IN BR AT FOG PRONE TERMINALS KLBT/KFLO IN THE PRE-DAWN HOURS
THROUGH SUNDAY. OTHERWISE EXPECT VFR...WITH A SLIGHT CHANCE SHOWERS
COAST TERMS FRI/SAT...BECOMING TERM WIDE SUNDAY AND MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1040 PM WEDNESDAY...CENTER OF HIGH PRESSURE WILL MOVE
OFFSHORE FROM THE NE STATES...BUT CONTINUE TO RIDGE BACK ACROSS
THE LOCAL WATERS OVERNIGHT. THIS PRESSURE PATTERN WILL PRODUCE A NE TO
ENE WIND DIRECTION OVERNIGHT. THE SFC PG WILL SLIGHTLY TIGHTEN AS
A RESULT OF THE HIGHS CENTER MOVING FURTHER AWAY FROM THE ILM
WATERS...AND THUS PRODUCE 15 TO OCCASIONALLY 20 KT WIND SPEEDS.
AS FOR SEAS...2 TO 4 FT NORTH OF CAPE FEAR...3 TO 5 FT FROM CAPE
FEAR SOUTHWARD. SEAS WILL PRIMARILY BE A SUMMATION OF 2 TO 4 FT
WIND DRIVEN WAVES AT 4 TO 5 SECOND PERIODS...AND A 1 TO 2 FT
RESIDUAL EASTERLY SWELL AT 9-12 SECOND PERIODS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...HIGH PRESSURE RIDGING DOWN FROM THE
NORTHEAST WILL GET SQUEEZED OUT AS COLD FRONT APPROACHES FROM THE
NORTHWEST LATE FRIDAY INTO SATURDAY. OVERALL WILL MAINTAIN A
DECENT E-NE FLOW THROUGH THURS WITH A SLIGHT BACKING TO THE NORTH
AS FRONT DRAWS CLOSER LATE FRI. PINCHED GRADIENT INITIALLY WILL
KEEP WINDS AROUND 15 KTS BUT AS GRADIENT RELAXES AND BACKS THROUGH
FRI EXPECT NE WINDS 10 TO 15 KTS AND DROPPING UNDER 10 KT FRI
NIGHT. SEAS WILL SUBSIDE FROM 3 TO 4 FT DOWN TO 2 TO 3 FT BY LATE
FRI AS WINDS DIMINISH. MAY SEE A FEW 5 FOOTERS IN OUTER WATERS EARLY
THURS.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...COLD FRONT WILL BE PUSHING SOUTH/OFFSHORE
AT THE START OF THE PERIOD. A WEAK SURGE WILL EXIST BEHIND THIS
FRONT...AND NE WINDS OF AROUND 10 KTS ARE EXPECTED THROUGH MUCH OF
THE WKND BEFORE SLOWLY VEERING TO THE SOUTH ON MONDAY...STILL
AROUND 10 KTS. THE LONG DURATION NE WIND ACROSS A LONG FETCH DOWN
THE EAST COAST WILL CREATE A 3-4 FT/8SEC NE SWELL WHICH COMBINES
WITH A 1-2 FT NE WIND WAVE TO PRODUCE 2-4 FT SEAS...WITH SOME 5
FOOTERS POSSIBLE NEAR THE 20NM BOUNDARY. AS WINDS TURN TO THE SOUTH
MONDAY...SEAS WILL FALL...BECOMING 2-3 FT ACROSS THE WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
830 PM EDT WED SEP 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER THROUGH THE
END OF THE WORK WEEK. A WEAK AND MOISTURE STARVED COLD FRONT WILL
MOVE ACROSS THE AREA EARLY SATURDAY...THEN DISSIPATE ALTOGETHER
DURING SUNDAY. HIGH PRESSURE RIDGING FROM THE NE STATES WILL
DOMINATE THE WEATHER THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 750 PM WEDNESDAY...CENTER OF SURFACE HIGH PRESSURE TO MOVE
OFFSHORE FROM THE MID-ATLANTIC AND NE STATES OVERNIGHT INTO
THURSDAY. LATEST SAT IMAGERY INDICATES THIN TO OCCASIONALLY OPAQUE
CIRRUS TO OVERSPREAD THE FA OVERNIGHT. AT THE SAME
TIME...EXTRAPOLATION OF THE SC DECK NEARSHORE AND OFFSHORE FROM
THE CAROLINAS VIA LATEST SAT IMAGERY...WILL MOVE PARTIALLY ONSHORE
MAINLY SOUTH OF THE SC/NC BORDER. LATEST HRRR OUTPUT ILLUSTRATES
POSSIBLE PCPN...IE.SHRA...REACHING THE COASTAL WATERS SOUTH OF THE
NC-SC BORDER. AT THIS POINT...THE DRY AIR ACROSS THE FA AND THE
SUBSIDENCE ALOFT SHOULD PREVENT THE PCPN FROM MOVING INLAND.
CURRENT MIN FORECAST LOOKS ON CUE AND SEE NO REASON TO DETOUR
FROM PREVIOUS THINKING.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...HIGH PRESSURE RIDGING BACK FROM CENTER
SHIFTING FURTHER EAST INTO THE ATLANTIC OFF THE NEW ENGLAND COAST
ON THURS INTO EARLY FRI. THIS WILL CONTINUE TO PRODUCE AN E-NE ON
SHORE FLOW. BY FRIDAY...THE HIGH WEAKENS AS IT GETS SQUEEZED OUT
BY A MOISTURE STARVED COLD FRONT MOVING INTO THE CAROLINAS FROM
THE NORTHWEST. THE ON SHORE FLOW MAY PRODUCE SOME PATCHES OF
CLOUDS MOVING IN FROM THE WATERS OVERNIGHT THURS. THE MODELS SHOW
PCP WATER DOWN LESS THAN AN INCH THROUGH THURS AFTN BUT THEN AN
INCREASE WITH THIS ON SHORE FLOW AND APPROACHING COLD FRONT LATE
FRI INTO SAT.
THE MID TO UPPER RIDGE SLIPS OFF THE EAST COAST BY FRIDAY AS
TROUGH DEEPENS DOWN THROUGH THE APPALACHIANS. THIS WILL PRODUCE A
RETURN FLOW VERY BRIEFLY ON FRI. BOTH THE NAM AND GFS SHOW VERY
LITTLE UPPER LEVEL FORCING WITH THIS SYSTEM WITH BEST ENERGY
COMING IN THROUGH THE MID LEVELS AS SHORTWAVE CROSSES THE AREA
THROUGH FRI AFTN INTO THE EVENING. DURING THIS TIME SHOULD SEE
INCREASED CLDS IN E-NE FLOW AT LOW LEVELS AND PASSING UPPER LEVEL
CLOUDS. THE MOISTURE PROFILES SHOW AN INCREASE IN RH UP GREATER
THAN 90 PERCENT ABOVE H5 BUT VERY DRY AIR REMAINING IN THE MID
LEVELS. THEREFORE EXPECT LIMITED...IF ANY CHC OF SHALLOW PASSING
SHWRS.
BY END OF PERIOD A DEEP NW FLOW WILL SET UP IN THE MID LEVELS AS H5
TROUGH PUSHES FARTHER EAST. THE MAIN EFFECT OF THE FRONT WILL BE
INCREASED CLOUDS FRI AND A REINFORCEMENT AND SHIFT TO MORE
NORTHERLY WINDS FRI INTO SAT WITH ONLY A SLIGHT CHC OF PCP FRI.
TEMPERATURES NEAR CLIMO THROUGH THE PERIOD...MID 80S AND MID 60S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...SPLIT FLOW PATTERN DEVELOPS AT THE START OF
THE PERIOD AS A NORTHERN STREAM TROUGH DRIVES A COLD FRONT TOWARDS
THE EASTERN CAROLINAS. THIS FRONT DIVES INTO A RELATIVELY DRY AIR
MASS...AND MID/UPPER FORCING ASSOCIATED WITH IT IS QUITE WEAK.
THEREFORE...EXPECT VERY LITTLE IN THE WAY OF PRECIP WITH ITS
PASSAGE...AND INSTEAD WILL JUST SEE AN INCREASE IN CLOUD COVER. AS
WINDS TURN MORE E/NE BEHIND THE FRONT...THIS ADVECTS ATLANTIC
MOISTURE INTO THE COLUMN. INHERITED FORECAST SHOWS SCHC POP FOR THE
WKND...AND WILL LEAVE THIS UNCHANGED. HOWEVER...FORECAST PROFILES
SHOW MUCH DRIER AIR ABOVE 750MB OR SO THAN WAS PREDICTED YESTERDAY
SINCE THE ATLANTIC FETCH REMAINS CONFINED TO THE LOWER PART OF THE
COLUMN. IF THIS TREND CONTINUES...MAY HAVE TO REMOVE ALL MENTION OF
TSTMS...ESPECIALLY ON SATURDAY. TEMPS WILL BE RIGHT AROUND CLIMO
DURING THE WKND.
SOUTHERN STREAM VORT ALONG THE GULF COAST WILL THEN ROTATE NORTHEAST
ON LEE SIDE OF DEVELOPING LONGWAVE TROUGH ACROSS THE PLAINS. AT THE
SAME TIME...DEEP SE FLOW DEVELOPS AND IT APPEARS THAT LATE MON/TUE
WILL BE THE BEST CHANCE FOR RAINFALL DURING THE EXTENDED. A SURFACE
REFLECTION TO THIS MID-LEVEL IMPULSE MAY WORK JUST WEST OF THE
CWA...WHICH ALLOWS FOR THE WARM FRONT AND ITS ASSOCIATED LIFT TO
CROSS US LATE MONDAY. STILL DIFFERENCES IN STRENGTH OF THIS FEATURE
FROM THE MODELS...SO WILL KEEP LOW-CHC POP FOR NOW. WILL NOTE THAT
IF THE ECMWF IS CORRECT THIS COULD END UP BEING A ROBUST RAINFALL
EVENT...BUT WITH GUIDANCE FLIPPING IN ITS AMPLIFICATION OF CENTRAL
5H TROUGH...WILL KEEP ONLY LIMITED QPF FOR NOW. BY WEDNESDAY THIS
FEATURE WILL BE WELL NE OF THE AREA AND DRYING WILL OCCUR.
TEMPS FOR THE FIRST HALF OF NEXT WEEK WILL BE AROUND CLIMO FOR
HIGHS...BUT LOWS WILL BE A FEW DEGREES ABOVE EACH NIGHT DUE TO
INCREASED SOUTHERLY FLOW AND CLOUD COVER.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 00Z...EXPECT VFR THROUGH THE VALID PERIOD...WITH EXCEPTION OF
POTENTIAL FOR SHORT-LIVED MVFR DUE TO FOG AT KLBT BEFORE SUNRISE.
NORTHEAST WINDS WILL BECOME LIGHT OVERNIGHT...WITH A FEW LINGERING
LOW TO MID LEVEL CLOUDS ACROSS THE AREA. GIVEN GUIDANCE AND FCST
SOUNDINGS...CANNOT RULE OUT FOG AT KLBT BEFORE DAYBREAK...THOUGH
CONFIDENCE IS LOWERED. AS A RESULT...HAVE OPTED TO INTRODUCE TEMPO
IN CURRENT FCST. AFTER SUNRISE...EAST- NORTHEAST WINDS WILL
INCREASE TO AOB 10 KTS FOR THE REMAINDER OF THE DAY. INCREASING
MOISTURE...ESPECIALLY ALONG THE COAST...WILL ALLOW FOR LOW CLOUDS
TO DEVELOP EARLY ON IN THE DAY. COVERAGE WILL BE FEW/SCT...THOUGH
DO NOT ANTICIPATE ANY RESTRICTIONS TO ARISE.
THE EXTENDED OUTLOOK THROUGH MONDAY...POTENTIAL FOR BRIEF REDUCED
VSBYS IN BR AT FOG PRONE TERMINALS KLBT/KFLO IN THE PRE-DAWN HOURS
THROUGH SUNDAY. OTHERWISE EXPECT VFR...WITH A SLIGHT CHANCE SHOWERS
COAST TERMS FRI/SAT...BECOMING TERM WIDE SUNDAY AND MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 750 PM WEDNESDAY...CENTER OF HIGH PRESSURE WILL MOVE
OFFSHORE FROM THE NE STATES...BUT CONTINUE TO RIDGE BACK ACROSS
THE AREA WATERS OVERNIGHT. THIS PRESSURE PATTERN WILL PRODUCE A
NE TO ENE WIND OVERNIGHT. THE SFC PG WILL SLIGHTLY TIGHTEN AS A
RESULT OF THE HIGHS CENTER MOVING FURTHER AWAY...AND PRODUCE 15 TO
OCCASIONALLY 20 KT WINDS. AS FOR SEAS...2 TO 4 FT NORTH OF CAPE
FEAR...3 TO 5 FT FROM CAPE FEAR SOUTHWARD. SEAS WILL PRIMARILY BE
A SUMMATION OF 2 TO 4 FT WIND DRIVEN WAVES AT 4 TO 5 SECOND
PERIODS...AND A 1 TO 2 FT RESIDUAL EASTERLY SWELL AT 9-12 SECOND
PERIODS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...HIGH PRESSURE RIDGING DOWN FROM THE
NORTHEAST WILL GET SQUEEZED OUT AS COLD FRONT APPROACHES FROM THE
NORTHWEST LATE FRIDAY INTO SATURDAY. OVERALL WILL MAINTAIN A
DECENT E-NE FLOW THROUGH THURS WITH A SLIGHT BACKING TO THE NORTH
AS FRONT DRAWS CLOSER LATE FRI. PINCHED GRADIENT INITIALLY WILL
KEEP WINDS AROUND 15 KTS BUT AS GRADIENT RELAXES AND BACKS THROUGH
FRI EXPECT NE WINDS 10 TO 15 KTS AND DROPPING UNDER 10 KT FRI
NIGHT. SEAS WILL SUBSIDE FROM 3 TO 4 FT DOWN TO 2 TO 3 FT BY LATE
FRI AS WINDS DIMINISH. MAY SEE A FEW 5 FTERS IN OUTER WATERS EARLY
THURS.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...COLD FRONT WILL BE PUSHING SOUTH/OFFSHORE
AT THE START OF THE PERIOD. A WEAK SURGE WILL EXIST BEHIND THIS
FRONT...AND NE WINDS OF AROUND 10 KTS ARE EXPECTED THROUGH MUCH OF
THE WKND BEFORE SLOWLY VEERING TO THE SOUTH ON MONDAY...STILL
AROUND 10 KTS. THE LONG DURATION NE WIND ACROSS A LONG FETCH DOWN
THE EAST COAST WILL CREATE A 3-4 FT/8SEC NE SWELL WHICH COMBINES
WITH A 1-2 FT NE WIND WAVE TO PRODUCE 2-4 FT SEAS...WITH SOME 5
FTERS POSSIBLE NEAR THE 20NM BOUNDARY. AS WINDS TURN TO THE SOUTH
MONDAY...SEAS WILL FALL...BECOMING 2-3 FT ACROSS THE WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...SGL
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1055 PM CDT WED SEP 12 2012
.DISCUSSION.../ISSUED AT 950 PM CDT/
FRONTOGENETIC RAINBAND HAS CONTINUED TO SHIFT SOUTHEAST WITH MID
LEVEL BOUNDARY THIS EVENING...WITH RAIN CONFINED TO AREAS SOUTH OF A
WAYNE TO LE MARS TO SPENCER LINE. TWO THINGS ARE LIKELY TO SPEED THE
DEMISE OF MEASURABLE PRECIPITATION...FIRST BEING THE WEAKENING OF
MID LEVEL AND UPPER LEVEL FORCING PAST 06Z...AND SECOND BEING
COMPENSATING SUBSIDENCE AROUND DEVELOPING LINE OF CONVECTION FIRING
ON LOWER FRONTAL ZONE IN PROXIMITY TO ELEVATED INSTABILITY ABOVE
BOUNDARY. SPED UP THE DEMISE BY THREE HOURS...AND CUT BACK THE AREA
OF PRECIPITATION SOMEWHAT IN THE FINAL THREE HOURS FROM 06Z-09Z.
OTHERWISE...OTHER VERY INTERESTING FEATURE OF THE EVENING HAS BEEN
THE IMPACT OF THE MESOHIGH PRODUCED FROM PRECIPITATION COLD POOL...
AND HOW IT HAS DRIVEN THE HIGHER DEWPOINTS NORTHWARD ON SOUTH TO
SOUTHWEST LOW LEVEL FLOW. DEWPOINT AT KHON DURING THE LATE AFTERNOON
SPIKED 12 DEGREES IN AN HOUR FROM 21Z-22Z...AND HAS PRETTY MUCH HELD
THROUGH THE EARLY EVENING AROUND 50...WHILE DEWPOINTS IN THE LOWER
TO MID 20S LURK JUST NORTH OF THIS BOUNDARY. MOST SOLUTIONS DO NOT
MOVE THIS VERY FAR THROUGH THE NIGHT...WITH JUST A SLOW DECREASE IN
TANDEM WITH COOLING. WILL STILL HEDGE SOME BETTER DRYING LATER IN
THE NIGHT TO THE NORTH. IF BOUNDARY WAS TO SINK SOUTH WITH CLEARING
AND WEAK FLOW...WOULD BE AN OPEN WINDOW FOR TEMPS TO PLUNGE AND
THREATEN A LITTLE FROST AROUND KHON AREA...BUT FOR NOW SEEMS A BIT
TOO LOW PROBABILITY TO MENTION. AS CLEARING OF HIGHER CLOUDS PUSHES
THROUGH THE MORE SATURATED SOUTHERN AREAS...ADDED IN SOME PATCHY FOG
A BIT SOONER IN SOUTHEAST SOUTH DAKOTA...MELDING INTO THE EARLIER
MENTION FOR EARLY THURSDAY MORNING. /CHAPMAN
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE TAF PERIOD. WHERE
LINGERING LOW LEVEL MOISTURE REMAINS AND SKIES CLEAR...COULD SEE
PATCHY RADIATION FOG DEVELOP. HURON RECEIVED LIMITED AMOUNTS OF
RAIN...SO ANY FOG THERE SHOULD BE QUITE LIMITED. FURTHER TO THE
SOUTH AND EAST...CONTINUED MENTION OF FOG IN KFSD TERMINAL...BUT
LEFT MENTION OUT OF KSUX AS CONFIDENCE IS LOW THAT SKIES WILL CLEAR
ENOUGH TO RESULT IN FOG. HRRR DEVELOPS PATCHY DENSE FOG AROUND SIOUX
FALLS. WITH SCATTERED CLOUD COVER...CONFIDENCE IS IFFY WITH
FOG...BUT THE EARLIER THE CLEARING OCCURS...THE BETTER POTENTIAL
THERE IS FOR LOCALLY DENSE FOG.
&&
.PREV DISCUSSION.../ISSUED AT 333 PM CDT/
BAND OF SHOWERS ASSOCIATED WITH MID LEVEL FRONTOGENESIS PRESENTLY
BISECTING THE CWA IN A SOUTHWEST TO NORTHEAST ORIENTATION AND
CONTINUING TO SLOWLY SAG TO THE SOUTH THIS AFTERNOON. WILL CONTINUE
TO SEE THIS TREND THROUGH THE EARLY NIGHTTIME HOURS...WITH
PRECIPITATION WINDING DOWN IN OUR FAR SOUTHEAST LATE TONIGHT AS
FORCING EXITS THE AREA. WILL SEE A DECREASE IN CLOUDS FROM NORTHWEST
TO SOUTHEAST THROUGH THE NIGHT...AS SURFACE HIGH PRESSURE BUILDS
BACK INTO THE REGION. IN RESPONSE...WINDS WILL DROP OFF TO NEAR
CALM...AND WITH CLEARING SKIES TEMPERATURES WILL DROP INTO THE UPPER
30S TO LOWER 40S OVER THE NORTHWESTERN HALF OF THE CWA...TO MID 40S
TO NEAR 50 IN THE SOUTHEAST WHERE CLOUDS WILL DECREASE LAST. WENT
AHEAD AND THREW IN SOME PATCHY FOG FOR SOME AREAS WITH THE WET
GROUND/CLEARING SKIES/AND LIGHT WINDS.
ON THURSDAY...BROAD HIGH PRESSURE CONTINUES TO SETTLE ACROSS THE
REGION. WHILE A WEAK BACKDOOR COLD FRONT WILL DROP THROUGH THE
AREA...WILL NOT SEE MUCH IN THE WAY OF WEATHER WITH THIS SYSTEM
OTHER THAN MAYBE A FEW MID CLOUDS AND A WIND SHIFT OUT OF THE
NORTHWEST IN THE AFTERNOON. HIGHS LOOK PLEASANT...IN THE LOWER TO
MID 70S.
LIGHT WINDS...CLEAR SKIES AND A WEAK RIDGE OF HIGH PRESSURE AT THE
SURFACE WILL INCREASE THE POTENTIAL FOR SOME CHILLY FRIDAY MORNING
LOW TEMPERATURES. THE COOLEST READING SHOULD BE ALONG AND EAST OF
INTERSTATE 29 WHERE UPPER 30S WILL BE LIKELY. TO THE WEST LOWS WILL
BE MORE IN THE 40 TO 45 DEGREE RANGE. ATY THIS TIME NOT CONCERNED
ABOUT FROST BUT WILL NEED TO KEEP ANY EYE OUT FOR THE POTENTIAL IN
SOME LOW LYING SPOTS OF NORTHWEST IA...SOUTHWEST MN AND FAR
SOUTHEAST SD.
RETURN FLOW WILL SET UP ON FRIDAY FOR WHAT SHOULD BE A PLEASANT DAY.
A WARM FAIRLY WELL AGREED UPON LOW LEVEL THERMAL FIELD SHOULD ALLOW
FOR HIGHS FROM THE 70 TO 75 DEGREE RANGE IN SOUTHWEST MN AND
NORTHWEST IA TO AROUND 80 IN CENTRAL SD.
WARMER LOW TEMPERATURES FRIDAY NIGHT AS A SOUTHERLY WIND KEEPS
TEMPERATURES UP A BIT. THE STRONGEST WINDS WILL BE IN CENTRAL SD
THEN GRADUALLY DEVELOP INTO THE EASTERN CWA OVERNIGHT. SO THE
WARMEST LOWS WILL BE IN CENTRAL SOUTH DAKOTA WHERE THE CONSRAW
OUTPUT WILL LIKELY HANDLE THE BEST WHILE THE FAR EASTERN CWA WILL
SEE TEMPERATURES DIP A LITTLE MORE BUT STILL NOT BOTTOM OUT AS WINDS
INCREASE THROUGH THE NIGHT.
SATURDAY WILL PROVE TO BE A BIT BREEZY BUT WARMER AS A TROUGH LOW
PRESSURE EXTENDS SOUTH INTO THE NORTHERN PLAINS. BUMPED HIGHS UP A
FEW DEGREES WITH PLENTY OF SUNSHINE EXPECTED AND A WARM LOW LEVEL
THERMAL FIELD. LOOKING AT AROUND 80 IN NORTHWEST IOWA TO 80 TO 85
REMAINDER OF AREA.
IN THE LATTER PERIODS(SUN/WED)...BROAD TROUGHING WILL DEVELOP ACROSS
SOUTHERN CANADA AND EXTEND SOUTH INTO THE NORTHERN PLAINS. THE
INITIAL WAVE THAT WILL BEGIN THIS DIGGING TROUGH PATTERN WILL BE
SUNDAY NIGHT WITH A PRETTY WARM AIR MASS AHEAD OF THE INCOMING
WAVE/FRONT. THERE IS SOME DECENT INSTABILITY AS THIS WAVE PASSES SO
WILL INCLUDE A CHANCE FOR SHOWERS AND THUNDERSTORMS SUNDAY NIGHT
INTO MONDAY. AFTER THIS MONDAY LOOKS A LITTLE COOLER WITH STRONG
NORTHWEST FLOW ALOFT AND HIGH PRESSURE BUILDING IN AT THE SURFACE.
TUESDAY WILL LIKELY BE A FAIRLY PLEASANT DAY AS HIGH PRESSURE
SHIFTS EAST AND RETURN FLOW GRADUALLY SETS UP. SOME DIFFERENCES IN
MODEL TIMING WITH RETURN FLOW SETTING UP ON EITHER TUESDAY OR LATER
INTO WEDNESDAY BUT TAT CAN BE EXPECTED AT THIS RANGE WITH A FAST
MOVING NORTHWEST FLOW ALOFT. SO...WILL LIKELY NOT HAVE THE EXTREMES
IN ON TUESDAY OR WEDNESDAY THAT COULD OCCUR SIMPLY BECAUSE THE
MARGIN FOR ERROR IS A LITTLE HIGHER IN THIS FASTER MOVING FLOW
REGIME. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
231 PM CDT TUE SEP 11 2012
.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...COLD FRONT OVER THE NORTHERN PLAINS WILL SLOWLY MOVE
EAST INTO CENTRAL WISCONSIN LATE TONIGHT INTO NORTHEAST WISCONSIN
WEDNESDAY MORNING. EXPECTING THIS FRONT TO MOVE THROUGH
DRY...THOUGH MODELS ARE TRYING TO SPIT OUT LIGHT SHOWERS ON
WEDNESDAY. FORECAST SOUNDINGS INDICATE CLOUD BASES ONLY FALLING TO
AROUND 10 KFT...SO IF ANY SHOWERS FORM...THEY WILL BE LIGHT.
OTHERWISE...LOW LEVEL WIND SHEAR WILL CRANK UP AGAIN TONIGHT. AS
THE FRONT MOVES IN HOWEVER...A LOOSENING PRESSURE GRADIENT WILL
CAUSE THE WIND SHEAR TO DIMINISH. IN GENERAL...VFR CONDITIONS OVER
THE TAF PERIOD.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TSK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1233 PM CDT TUE SEP 11 2012
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
319 AM CDT TUE SEP 11 2012
MAIN FORECAST CONCERNS ARE ON FIRE WEATHER TODAY...THEN
PRECIPITATION CHANCES AND TRENDS WEDNESDAY THROUGH THURSDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED DEEP TROUGHING OVER SOUTHWEST CANADA INTO THE PACIFIC
NORTHWEST AND RIDGING DOWNSTREAM FROM THE CENTRAL PLAINS INTO THE
WESTERN GREAT LAKES REGION. SHORTWAVES OF NOTE INCLUDE ONE OVER
NORTHWEST SOUTH DAKOTA...THEN A COMPLEX OF THEM IN THE MONSOONAL
MOISTURE ACROSS THE DESERT SOUTHWEST. ASSOCIATED WITH THE SOUTH
DAKOTA SHORTWAVE IS A SURFACE LOW JUST NORTH OF PIERRE. A TIGHT
PRESSURE GRADIENT EXISTS AHEAD OF THIS LOW INTO THE FORECAST
AREA...RESULTING IN BREEZY SOUTH WINDS. THESE WINDS HAVE KEPT
TEMPERATURES UP IN THE MID 50S TO MID 60S. HIGHER ALOFT...AT
850MB...PROFILER DATA SHOWED A SOUTHWEST 35-50 KT JET EXTENDING
FROM THE CENTRAL PLAINS INTO THE FORECAST AREA...ADVECTING WARM
AIR NORTHEASTWARD. 850MB TEMPS HAVE CLIMBED TO 18-22C PER RAP
ANALYSIS...COMPARED TO 00Z RAOBS WHICH WERE BETWEEN 16-18C.
AIRMASS ALSO REMAINS QUITE DRY ACROSS THE CENTRAL PLAINS INTO THE
FORECAST AREA...NOTED BY GOES SOUNDER PRECIPITABLE WATER VALUES OF
0.5-0.6 INCHES OR 60 PERCENT OF NORMAL. ALSO REFLECTIVE OF THE DRY
AIR WAS THE 00Z MPX SOUNDING WHICH HAD DEWPOINT DEPRESSIONS OF 15C
OR MORE FROM THE SURFACE TO 350MB. THE 00Z OAX SOUNDING WAS EVEN
DRIER. SATELLITE IMAGERY DEPICTING ONLY A LITTLE CIRRUS OVER THE
FORECAST AREA.
TODAY AND TONIGHT...MODELS TAKE THE DEEP SOUTHWEST CANADA TROUGH
EASTWARD INTO SOUTH CENTRAL CANADA BY 12Z WEDNESDAY. AS THIS TROUGH
PUSHES EAST...IT WILL PICK UP THE SHORTWAVE AND SURFACE LOW IN SOUTH
DAKOTA...LIFTING THEM INTO NORTHERN ONTARIO. THE ASSOCIATED COLD
FRONT IS TRENDING SLIGHTLY FASTER...NOW PROGGED TO REACH AROUND LA
CROSSE WI AT 12Z WEDNESDAY. THE WARM AIR SURGE AHEAD OF THE FRONT
CONTINUES TODAY WITH 850MB TEMPS PROGGED TO TOP OUT AT 20-22C FOR
18Z. THESE ARE NEAR 2 STANDARD DEVIATIONS ABOVE NORMAL. PLENTY OF
DRY AIR REMAINS...AND WITH 925MB SOUTHWEST WINDS OF 25-30 KT
PROMOTING MIXING AS WELL AS PLENTY OF SUN OUTSIDE OF SOME CIRRUS
LATE IN THE DAY...SHOULD HAVE NO PROBLEM MIXING UP TO THOSE 850MB
TEMPS. THUS...ANTICIPATING HIGHS SIMILAR TO THE PREVIOUS
FORECASTS...FROM THE MID 80S TO LOW 90S. GIVEN THE DRY AIR...BREEZY
CONDITIONS AND WARM TEMPERATURES...CRITICAL FIRE WEATHER CONDITIONS
ARE LIKELY. SEE FIRE WEATHER DISCUSSION FOR MORE DETAILS. FOR
TONIGHT...ALTHOUGH THE FRONT IS MOVING IN SLIGHTLY FASTER...ALL THE
FRONTOGENETIC FORCING AND MOISTURE STILL REMAINS NORTHWEST OF THE
FORECAST AREA. THEREFORE...EXPECTING DRY CONDITIONS AND ONLY A
GRADUAL INCREASE IN CLOUDS. WARM NIGHT ON TAP GIVEN WARM START
AND BREEZY WINDS AHEAD OF THE FRONT. MOST LOCATIONS SHOULD SEE LOWS
IN THE 60S.
WEDNESDAY AND WEDNESDAY NIGHT...ON THE WEST SIDE OF THE DEEP
SOUTHWEST CANADA TROUGH...MODELS ARE IN GOOD AGREEMENT DROPPING A
POTENT SHORTWAVE DOWN INTO THE NORTHERN PLAINS BY 12Z THURSDAY. THIS
SHORTWAVE LOOKS TO HELP KICK OUT ALL OF THE MONSOONAL SHORTWAVES...
EJECTING THEM NORTHEAST ACROSS THE FORECAST AREA. IT APPEARS A
COMBINATION OF THESE VARIOUS SHORTWAVES...ALONG WITH THE POTENT
SHORTWAVE TROUGH...WILL HELP TO KEEP THE COLD FRONT THAT IS NEAR LA
CROSSE AT 12Z WEDNESDAY MOVING TO THE EAST. OF INTEREST...THOUGH...
IS THE FORCING BEHIND THIS COLD FRONT. MODELS DEPICT AN 80-120 KT
JET AT THE TROPOPAUSE PERSISTING BOTH WEDNESDAY AND WEDNESDAY NIGHT
FROM CENTRAL MINNESOTA INTO NORTHERN ONTARIO...PLACING THE FORECAST
AREA IN THE RIGHT ENTRANCE REGION FOR UPPER LEVEL DIVERGENCE. LOWER
IN THE TROPOSPHERE...PLENTY OF LOW TO MID LEVEL FRONTOGENESIS
EXISTS...THOUGH THERE ARE SOME DIFFERENCES IN THE STRENGTH. FOR
EXAMPLE...THE 11.00Z NAM/REGIONAL CANADIAN ARE QUITE A BIT WEAKER
THAN THE 11.00Z GFS/UKMET AND AS SUCH IS A LOT LIGHTER WHEN IT COMES
TO ITS QPF FORECAST. IN FACT...THE 11.00Z NAM DEPICTS VERY LITTLE
RAIN FOR LOCATIONS NORTH OF I-90. CERTAINLY PLENTY OF MOISTURE
EXISTS WITH BOTH THE 11.00Z NAM AND GFS SHOWING AN AXIS OF 1-1.4
INCHES OF PRECIPITABLE WATER WHERE THE FRONTOGENESIS IS. GIVEN ALL
THE FORCING...WOULD HAVE TO THINK A WETTER SOLUTION IS MORE LIKELY.
SREF PROBABILITIES DEPICTING SOME SIMILAR UNCERTAINTY WITH HIGHER
PROBABILITIES OF PRECIPITATION SOUTH OF I-90. WILL TAILOR FORECAST
THIS WAY UNTIL MODELS CAN GET INTO BETTER AGREEMENT. DID REMOVE
THUNDER AS LAPSE RATES UNDER THE FRONTOGENETICAL BAND ARE MAINLY
MOIST-ADIABATIC. THERE IS SOME NEGATIVE EPV RESULTING FROM SLANTWISE
INSTABILITY...SO A COUPLE LIGHTNING STRIKES CANNOT BE RULED OUT.
HOWEVER...MENTIONING ISOLATED THUNDER FOR A WIDESPREAD AREA SEEMS
TOO HIGH OF A PROBABILITY. TEMPERATURES ARE QUITE TRICKY...SINCE
WHERE IT RAINS READINGS WILL BE HELD DOWN DUE TO EVAPORATIVE
COOLING. CERTAINLY WITH THE FASTER FRONT AND INCREASING CLOUDS
THROUGH THE DAY WEDNESDAY...HAVE HAD TO COOL HIGHS DOWN. FOR
NOW...HAVE TAKEN A BLEND OF GUIDANCE FOR BOTH HIGHS AND LOWS...WITH
A FALLING TEMP TREND IN THE AFTERNOON FOR THE PRECIPITATION THAT
DEVELOPS.
THURSDAY AND THURSDAY NIGHT...SOME DIFFERENCES EXIST WITH THE
HANDLING OF THE POTENT TROUGH DROPPING INTO THE NORTHERN PLAINS
THURSDAY MORNING. THE 11.00Z NAM IS AN OUTLIER...TAKING THE TROUGH
EAST TO LAKE SUPERIOR THURSDAY NIGHT. ALL OTHER MODELS
(GFS...ECMWF...UKMET...CANADIAN) HAVE THE TROUGH DIGGING DOWN
TOWARDS IOWA AND CLOSING OFF AS AN UPPER LOW. WILL FOLLOW THIS
GROUP...THOUGH EVEN WITHIN THESE THERE ARE ISSUES...MAINLY
PERTAINING TO HOW DEEP THE UPPER LOW BECOMES. FOR EXAMPLE...THE
DEEPEST 11.00Z CANADIAN PRODUCES A WAVE ALONG THE COLD FRONT...
CAUSING A DEFORMATION/FRONTOGENESIS AREA TO PERSIST OVER EASTERN
IOWA INTO THE FORECAST AREA THROUGH THE ENTIRE PERIOD. AS SUCH...THE
CANADIAN KEEPS THE AREA IN MODERATE TO HEAVY RAIN. THERE HAVE BEEN
PAST ECMWF AND GFS RUNS THAT HAVE SUGGESTED THIS SCENARIO...BUT THE
LATEST 11.00Z GFS AND ECMWF SUGGEST THE FRONTOGENESIS ZONE WILL BE
ABLE TO CONTINUE PUSHING EASTWARD AND NEARLY OUT OF THE AREA BY 12Z
FRIDAY. FOR NOW WILL LEAN TOWARDS THE GFS/ECMWF CONSENSUS BEING IN
THE MIDDLE OF THE NAM/CANADIAN EXTREMES...BUT REALIZE THIS PORTION
OF THE FORECAST HAS SOME UNCERTAINTY. ONE THING THAT DOES SEEM SURE
IS THAT THE SOUTHEASTERN HALF OF THE FORECAST AREA WILL SEE RAIN
THURSDAY WITH THE FRONTOGENESIS ZONE IN PLACE THERE BY ALL MODELS.
THUS...PRECIPITATION CHANCES RANGE FROM 70-90 THERE. LOWER CHANCES
OF PRECIPITATION EXIST ELSEWHERE WITH TIMING ISSUES OF THE
FRONTOGENESIS ZONE MOVING OFF. ALTHOUGH MOST MODELS HAVE
PRECIPITATION MOVING OUT OF THE FORECAST AREA THURSDAY NIGHT...
KEEPING AT LEAST A 20 PERCENT CHANCE EVERYWHERE TO ACCOUNT FOR THE
CANADIAN AND PREVIOUS GFS/ECMWF RUNS. MUCH COOLER TEMPERATURES
ANTICIPATED DURING THIS PERIOD...DUE TO A COMBINATION OF COLD
ADVECTION BEHIND THE FRONT KNOCKING 850MB TEMPS DOWN TO 6-8C...AS
WELL AS EVAPORATIVE/DYNAMIC COOLING WHERE IT IS RAINING. POTENTIAL
EXISTS FOR HIGHS ON THURSDAY IN SAY CRAWFORD COUNTY TO NOT GET ABOVE
60.
.LONG TERM...FRIDAY THROUGH MONDAY NIGHT
319 AM CDT TUE SEP 11 2012
FORECAST DURING THIS PERIOD HIGHLY DEPENDENT ON THE EVOLUTION OF THE
UPPER LEVEL LOW THAT IS EXPECTED TO BECOME CLOSED OFF DURING THE DAY
ON FRIDAY SOMEWHERE ACROSS THE UPPER MIDWEST...WITH THE POTENTIAL TO
LINGER INTO THE FIRST PART OF THE UPCOMING WEEKEND. BY 12Z
FRIDAY...SIGNIFICANT MODEL SPREAD IN LOCATION/STRENGTH OF THE UPPER
LEVEL FEATURE. THE 11.00Z GFS WAS MORE PROGRESSIVE WITH THE
SYSTEM...PUSHING IT QUICKLY EASTWARD BY 12Z SATURDAY SUCH THAT THE
FORECAST AREA WOULD BE DRY. MEANWHILE THE 10.12Z ECMWF AND 11.00Z
CANADIAN WERE STRONGER/SLOWER SOLUTIONS...WHICH PIVOTED MORE
ACROSS THE FORECAST AREA. OF NOTE WAS THE 11.00Z CANADIAN WHICH
DEPICTED SEVERAL DEFORMATION RAIN BANDS FRIDAY NIGHT INTO SATURDAY
RESULTING IN A LARGE SWATH OF MODERATE TO HEAVY RAINFALL ACROSS
PORTIONS OF THE AREA. TO ADD TO THE UNCERTAINTY...THE LATEST
11.00Z ECMWF CAME IN MUCH FASTER THAN ALL GUIDANCE AND QUITE
DIFFERENT FROM ITS PREVIOUS RUN. THIS SOLUTION WOULD MEAN MOST OF
FRIDAY INTO THE WEEKEND THE FORECAST AREA WOULD BE DRY WITH NEAR
NORMAL TEMPERATURES. 11.00Z GFS ENSEMBLES REFLECT THE SAME
UNCERTAINTY ON THE UPPER LOW DEPTH/TRACK THAT THE INDIVIDUAL
MODELS SHOW.
GIVEN THE LARGE VARIABILITY IN SOLUTIONS...AND POOR RUN-TO-RUN MODEL
CONSISTENCY...A MODEL CONSENSUS IS APPROPRIATE WHICH KEEPS
HIGHER PRECIPITATIONS CHANCES FRIDAY/FRIDAY NIGHT CONFINED EAST OF
THE MISSISSIPPI RIVER...THEN REDUCES TO JUST 20 PERCENT ON SATURDAY.
REGARDING TEMPERATURES...TRICKY AS WELL...THOUGH FRIDAY LOOKS TO
BE THE COOLEST DAY POTENTIALLY WITH MORE CLOUDS AND HIGHER
PRECIPITATION CHANCES. MODERATING TEMPERATURES TO NEAR NORMAL BY
SUNDAY WITH WEAK NORTHWEST TO NEAR ZONAL FLOW EXPECTED. GOING INTO
EARLY NEXT WEEK...ANOTHER DIGGING UPPER TROUGH WITH SURFACE FRONT
LEADS TO LOW END RAIN CHANCES AND COOLER TEMPERATURES FOR MONDAY
INTO MONDAY NIGHT. PLENTY OF UNCERTAINTY EXISTS TOO ON THIS
DIGGING UPPER TROUGH.
&&
.AVIATION...THROUGH 18Z WEDNESDAY
1233 PM CDT TUE SEP 11 2012
MAIN CONCERN IS STRONG WINDS THROUGH THIS AFTERNOON...THEN RAIN
CHANCES LATE IN THE PERIOD. SURFACE MAP EARLY THIS AFTERNOON HAS HIGH
PRESSURE OVER THE OHIO RIVER VALLEY WHILE A COLD FRONT WAS PUSHING
SOUTHEAST ACROSS THE DAKOTAS/CENTRAL PLAINS. PRESSURE GRADIENT AND
DEEP MIXING BETWEEN THESE TWO WEATHER SYSTEMS WILL PRODUCE GUSTY
SOUTH WINDS IN THE 15-25KT RANGE WITH GUSTS 25-35KT. STRONGEST
WINDS EXPECTED ACROSS THE BLUFFTOPS OF SOUTHWEST WISCONSIN AND
HIGHER/OPEN TERRAIN OF SOUTHEAST MN AND NORTHEAST IA. LOOK FOR
THESE WINDS TO SUBSIDE BY SUNSET...THEN SHIFT TO THE NORTHWEST BY
12Z AS THE COLD FRONT PROGRESSES THROUGH THE AREA. EXPECTING
HIGH/MID CLOUDS WITH BASES AOA 12KFT TO BE ON A GRADUAL INCREASE
TONIGHT WITH THE APPROACH OF THE FRONT...THEN LOWERING TO AROUND
8KFT BY 15Z BEHIND THE FRONT. A WAVE OF LOW PRESSURE IS THEN
EXPECTED TO RIDE UP ALONG THIS FRONTAL BOUNDARY AS IT PUSHES
SOUTHEAST ACROSS THE AREA. THIS WILL LIKELY PUSH SOME -SHRA
ACTIVITY INTO THE AREA BY AFTERNOON. MODEL SOUNDING SHOW PRETTY
DRY SUB-CLOUD LAYER THROUGH 18Z...SO OPTED TO KEEP -SHRA MENTION
OUT OF THIS TAF ISSUANCE (THROUGH WED 18Z).
&&
.CLIMATE...TODAY
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
319 AM CDT TUE SEP 11 2012
CRITICAL FIRE WEATHER CONDITIONS REMAIN ON TAP FROM LATE THIS
MORNING THROUGH THIS EVENING ACROSS PORTIONS OF SOUTHEAST MINNESOTA
AND NORTHEAST IOWA. SOUTH TO SOUTHWEST WINDS OF 20 TO 25 MPH WITH
GUSTS OF 30 TO 40 MPH...AND RELATIVE HUMIDITY VALUES OF 20 TO
25 PERCENT ARE EXPECTED...ESPECIALLY DURING THE AFTERNOON HOURS. THE
COMBINATION OF STRONG WINDS AND LOW RH VALUES WILL PRODUCE DANGER
CONDITIONS FOR WILDFIRES. THE RED FLAG WARNING REMAINS IN EFFECT
FROM OLMSTED COUNTY TO CHICKASAW COUNTY WESTWARD. THE WINDS WILL
SUBSIDE LATE TUESDAY EVENING AS A COLD FRONT APPROACHES THE AREA.
HOWEVER...THE COLD FRONT WILL RESULT IN A WIND SHIFT...WITH WINDS
SWITCHING TO THE NORTHWEST. CONDITIONS SHOULD IMPROVE THROUGH THE
NIGHT INTO EARLY WEDNESDAY MORNING AS THE PRESSURE GRADIENT
WEAKENS...TEMPERATURES COOL AND PRECIPITATION EVENTUALLY DEVELOPS.
THROUGH COORDINATION WITH LOCAL FIRE WEATHER PARTNERS
YESTERDAY...LOCATIONS NEAR AND EAST OF THE MISSISSIPPI RIVER HAVE
NOT BEEN INCLUDED IN ANY FIRE WEATHER HEADLINES BECAUSE OF RECENT
RAINS AND FUELS NOT CONDUCIVE TO EXPLOSIVE FIRE GROWTH. SOME DRY
AREAS WILL HAVE TO BE WATCHED CLOSELY...ESPECIALLY SOUTH FACING
SLOPES AND SANDY AREAS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
319 AM CDT TUE SEP 11 2012
WI...NONE.
MN...RED FLAG WARNING FROM 11 AM THIS MORNING TO 9 PM CDT THIS
EVENING FOR MNZ086-087-094-095.
IA...RED FLAG WARNING FROM 11 AM THIS MORNING TO 9 PM CDT THIS
EVENING FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...AJ
LONG TERM...ZT
AVIATION...DAS
CLIMATE........BOYNE
FIRE WEATHER...WETENKAMP/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
620 AM CDT TUE SEP 11 2012
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
319 AM CDT TUE SEP 11 2012
MAIN FORECAST CONCERNS ARE ON FIRE WEATHER TODAY...THEN
PRECIPITATION CHANCES AND TRENDS WEDNESDAY THROUGH THURSDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED DEEP TROUGHING OVER SOUTHWEST CANADA INTO THE PACIFIC
NORTHWEST AND RIDGING DOWNSTREAM FROM THE CENTRAL PLAINS INTO THE
WESTERN GREAT LAKES REGION. SHORTWAVES OF NOTE INCLUDE ONE OVER
NORTHWEST SOUTH DAKOTA...THEN A COMPLEX OF THEM IN THE MONSOONAL
MOISTURE ACROSS THE DESERT SOUTHWEST. ASSOCIATED WITH THE SOUTH
DAKOTA SHORTWAVE IS A SURFACE LOW JUST NORTH OF PIERRE. A TIGHT
PRESSURE GRADIENT EXISTS AHEAD OF THIS LOW INTO THE FORECAST
AREA...RESULTING IN BREEZY SOUTH WINDS. THESE WINDS HAVE KEPT
TEMPERATURES UP IN THE MID 50S TO MID 60S. HIGHER ALOFT...AT
850MB...PROFILER DATA SHOWED A SOUTHWEST 35-50 KT JET EXTENDING
FROM THE CENTRAL PLAINS INTO THE FORECAST AREA...ADVECTING WARM
AIR NORTHEASTWARD. 850MB TEMPS HAVE CLIMBED TO 18-22C PER RAP
ANALYSIS...COMPARED TO 00Z RAOBS WHICH WERE BETWEEN 16-18C.
AIRMASS ALSO REMAINS QUITE DRY ACROSS THE CENTRAL PLAINS INTO THE
FORECAST AREA...NOTED BY GOES SOUNDER PRECIPITABLE WATER VALUES OF
0.5-0.6 INCHES OR 60 PERCENT OF NORMAL. ALSO REFLECTIVE OF THE DRY
AIR WAS THE 00Z MPX SOUNDING WHICH HAD DEWPOINT DEPRESSIONS OF 15C
OR MORE FROM THE SURFACE TO 350MB. THE 00Z OAX SOUNDING WAS EVEN
DRIER. SATELLITE IMAGERY DEPICTING ONLY A LITTLE CIRRUS OVER THE
FORECAST AREA.
TODAY AND TONIGHT...MODELS TAKE THE DEEP SOUTHWEST CANADA TROUGH
EASTWARD INTO SOUTH CENTRAL CANADA BY 12Z WEDNESDAY. AS THIS TROUGH
PUSHES EAST...IT WILL PICK UP THE SHORTWAVE AND SURFACE LOW IN SOUTH
DAKOTA...LIFTING THEM INTO NORTHERN ONTARIO. THE ASSOCIATED COLD
FRONT IS TRENDING SLIGHTLY FASTER...NOW PROGGED TO REACH AROUND LA
CROSSE WI AT 12Z WEDNESDAY. THE WARM AIR SURGE AHEAD OF THE FRONT
CONTINUES TODAY WITH 850MB TEMPS PROGGED TO TOP OUT AT 20-22C FOR
18Z. THESE ARE NEAR 2 STANDARD DEVIATIONS ABOVE NORMAL. PLENTY OF
DRY AIR REMAINS...AND WITH 925MB SOUTHWEST WINDS OF 25-30 KT
PROMOTING MIXING AS WELL AS PLENTY OF SUN OUTSIDE OF SOME CIRRUS
LATE IN THE DAY...SHOULD HAVE NO PROBLEM MIXING UP TO THOSE 850MB
TEMPS. THUS...ANTICIPATING HIGHS SIMILAR TO THE PREVIOUS
FORECASTS...FROM THE MID 80S TO LOW 90S. GIVEN THE DRY AIR...BREEZY
CONDITIONS AND WARM TEMPERATURES...CRITICAL FIRE WEATHER CONDITIONS
ARE LIKELY. SEE FIRE WEATHER DISCUSSION FOR MORE DETAILS. FOR
TONIGHT...ALTHOUGH THE FRONT IS MOVING IN SLIGHTLY FASTER...ALL THE
FRONTOGENETIC FORCING AND MOISTURE STILL REMAINS NORTHWEST OF THE
FORECAST AREA. THEREFORE...EXPECTING DRY CONDITIONS AND ONLY A
GRADUAL INCREASE IN CLOUDS. WARM NIGHT ON TAP GIVEN WARM START
AND BREEZY WINDS AHEAD OF THE FRONT. MOST LOCATIONS SHOULD SEE LOWS
IN THE 60S.
WEDNESDAY AND WEDNESDAY NIGHT...ON THE WEST SIDE OF THE DEEP
SOUTHWEST CANADA TROUGH...MODELS ARE IN GOOD AGREEMENT DROPPING A
POTENT SHORTWAVE DOWN INTO THE NORTHERN PLAINS BY 12Z THURSDAY. THIS
SHORTWAVE LOOKS TO HELP KICK OUT ALL OF THE MONSOONAL SHORTWAVES...
EJECTING THEM NORTHEAST ACROSS THE FORECAST AREA. IT APPEARS A
COMBINATION OF THESE VARIOUS SHORTWAVES...ALONG WITH THE POTENT
SHORTWAVE TROUGH...WILL HELP TO KEEP THE COLD FRONT THAT IS NEAR LA
CROSSE AT 12Z WEDNESDAY MOVING TO THE EAST. OF INTEREST...THOUGH...
IS THE FORCING BEHIND THIS COLD FRONT. MODELS DEPICT AN 80-120 KT
JET AT THE TROPOPAUSE PERSISTING BOTH WEDNESDAY AND WEDNESDAY NIGHT
FROM CENTRAL MINNESOTA INTO NORTHERN ONTARIO...PLACING THE FORECAST
AREA IN THE RIGHT ENTRANCE REGION FOR UPPER LEVEL DIVERGENCE. LOWER
IN THE TROPOSPHERE...PLENTY OF LOW TO MID LEVEL FRONTOGENESIS
EXISTS...THOUGH THERE ARE SOME DIFFERENCES IN THE STRENGTH. FOR
EXAMPLE...THE 11.00Z NAM/REGIONAL CANADIAN ARE QUITE A BIT WEAKER
THAN THE 11.00Z GFS/UKMET AND AS SUCH IS A LOT LIGHTER WHEN IT COMES
TO ITS QPF FORECAST. IN FACT...THE 11.00Z NAM DEPICTS VERY LITTLE
RAIN FOR LOCATIONS NORTH OF I-90. CERTAINLY PLENTY OF MOISTURE
EXISTS WITH BOTH THE 11.00Z NAM AND GFS SHOWING AN AXIS OF 1-1.4
INCHES OF PRECIPITABLE WATER WHERE THE FRONTOGENESIS IS. GIVEN ALL
THE FORCING...WOULD HAVE TO THINK A WETTER SOLUTION IS MORE LIKELY.
SREF PROBABILITIES DEPICTING SOME SIMILAR UNCERTAINTY WITH HIGHER
PROBABILITIES OF PRECIPITATION SOUTH OF I-90. WILL TAILOR FORECAST
THIS WAY UNTIL MODELS CAN GET INTO BETTER AGREEMENT. DID REMOVE
THUNDER AS LAPSE RATES UNDER THE FRONTOGENETICAL BAND ARE MAINLY
MOIST-ADIABATIC. THERE IS SOME NEGATIVE EPV RESULTING FROM SLANTWISE
INSTABILITY...SO A COUPLE LIGHTNING STRIKES CANNOT BE RULED OUT.
HOWEVER...MENTIONING ISOLATED THUNDER FOR A WIDESPREAD AREA SEEMS
TOO HIGH OF A PROBABILITY. TEMPERATURES ARE QUITE TRICKY...SINCE
WHERE IT RAINS READINGS WILL BE HELD DOWN DUE TO EVAPORATIVE
COOLING. CERTAINLY WITH THE FASTER FRONT AND INCREASING CLOUDS
THROUGH THE DAY WEDNESDAY...HAVE HAD TO COOL HIGHS DOWN. FOR
NOW...HAVE TAKEN A BLEND OF GUIDANCE FOR BOTH HIGHS AND LOWS...WITH
A FALLING TEMP TREND IN THE AFTERNOON FOR THE PRECIPITATION THAT
DEVELOPS.
THURSDAY AND THURSDAY NIGHT...SOME DIFFERENCES EXIST WITH THE
HANDLING OF THE POTENT TROUGH DROPPING INTO THE NORTHERN PLAINS
THURSDAY MORNING. THE 11.00Z NAM IS AN OUTLIER...TAKING THE TROUGH
EAST TO LAKE SUPERIOR THURSDAY NIGHT. ALL OTHER MODELS
(GFS...ECMWF...UKMET...CANADIAN) HAVE THE TROUGH DIGGING DOWN
TOWARDS IOWA AND CLOSING OFF AS AN UPPER LOW. WILL FOLLOW THIS
GROUP...THOUGH EVEN WITHIN THESE THERE ARE ISSUES...MAINLY
PERTAINING TO HOW DEEP THE UPPER LOW BECOMES. FOR EXAMPLE...THE
DEEPEST 11.00Z CANADIAN PRODUCES A WAVE ALONG THE COLD FRONT...
CAUSING A DEFORMATION/FRONTOGENESIS AREA TO PERSIST OVER EASTERN
IOWA INTO THE FORECAST AREA THROUGH THE ENTIRE PERIOD. AS SUCH...THE
CANADIAN KEEPS THE AREA IN MODERATE TO HEAVY RAIN. THERE HAVE BEEN
PAST ECMWF AND GFS RUNS THAT HAVE SUGGESTED THIS SCENARIO...BUT THE
LATEST 11.00Z GFS AND ECMWF SUGGEST THE FRONTOGENESIS ZONE WILL BE
ABLE TO CONTINUE PUSHING EASTWARD AND NEARLY OUT OF THE AREA BY 12Z
FRIDAY. FOR NOW WILL LEAN TOWARDS THE GFS/ECMWF CONSENSUS BEING IN
THE MIDDLE OF THE NAM/CANADIAN EXTREMES...BUT REALIZE THIS PORTION
OF THE FORECAST HAS SOME UNCERTAINTY. ONE THING THAT DOES SEEM SURE
IS THAT THE SOUTHEASTERN HALF OF THE FORECAST AREA WILL SEE RAIN
THURSDAY WITH THE FRONTOGENESIS ZONE IN PLACE THERE BY ALL MODELS.
THUS...PRECIPITATION CHANCES RANGE FROM 70-90 THERE. LOWER CHANCES
OF PRECIPITATION EXIST ELSEWHERE WITH TIMING ISSUES OF THE
FRONTOGENESIS ZONE MOVING OFF. ALTHOUGH MOST MODELS HAVE
PRECIPITATION MOVING OUT OF THE FORECAST AREA THURSDAY NIGHT...
KEEPING AT LEAST A 20 PERCENT CHANCE EVERYWHERE TO ACCOUNT FOR THE
CANADIAN AND PREVIOUS GFS/ECMWF RUNS. MUCH COOLER TEMPERATURES
ANTICIPATED DURING THIS PERIOD...DUE TO A COMBINATION OF COLD
ADVECTION BEHIND THE FRONT KNOCKING 850MB TEMPS DOWN TO 6-8C...AS
WELL AS EVAPORATIVE/DYNAMIC COOLING WHERE IT IS RAINING. POTENTIAL
EXISTS FOR HIGHS ON THURSDAY IN SAY CRAWFORD COUNTY TO NOT GET ABOVE
60.
.LONG TERM...FRIDAY THROUGH MONDAY NIGHT
319 AM CDT TUE SEP 11 2012
FORECAST DURING THIS PERIOD HIGHLY DEPENDENT ON THE EVOLUTION OF THE
UPPER LEVEL LOW THAT IS EXPECTED TO BECOME CLOSED OFF DURING THE DAY
ON FRIDAY SOMEWHERE ACROSS THE UPPER MIDWEST...WITH THE POTENTIAL TO
LINGER INTO THE FIRST PART OF THE UPCOMING WEEKEND. BY 12Z
FRIDAY...SIGNIFICANT MODEL SPREAD IN LOCATION/STRENGTH OF THE UPPER
LEVEL FEATURE. THE 11.00Z GFS WAS MORE PROGRESSIVE WITH THE
SYSTEM...PUSHING IT QUICKLY EASTWARD BY 12Z SATURDAY SUCH THAT THE
FORECAST AREA WOULD BE DRY. MEANWHILE THE 10.12Z ECMWF AND 11.00Z
CANADIAN WERE STRONGER/SLOWER SOLUTIONS...WHICH PIVOTED MORE
ACROSS THE FORECAST AREA. OF NOTE WAS THE 11.00Z CANADIAN WHICH
DEPICTED SEVERAL DEFORMATION RAIN BANDS FRIDAY NIGHT INTO SATURDAY
RESULTING IN A LARGE SWATH OF MODERATE TO HEAVY RAINFALL ACROSS
PORTIONS OF THE AREA. TO ADD TO THE UNCERTAINTY...THE LATEST
11.00Z ECMWF CAME IN MUCH FASTER THAN ALL GUIDANCE AND QUITE
DIFFERENT FROM ITS PREVIOUS RUN. THIS SOLUTION WOULD MEAN MOST OF
FRIDAY INTO THE WEEKEND THE FORECAST AREA WOULD BE DRY WITH NEAR
NORMAL TEMPERATURES. 11.00Z GFS ENSEMBLES REFLECT THE SAME
UNCERTAINTY ON THE UPPER LOW DEPTH/TRACK THAT THE INDIVIDUAL
MODELS SHOW.
GIVEN THE LARGE VARIABILITY IN SOLUTIONS...AND POOR RUN-TO-RUN MODEL
CONSISTENCY...A MODEL CONSENSUS IS APPROPRIATE WHICH KEEPS
HIGHER PRECIPITATIONS CHANCES FRIDAY/FRIDAY NIGHT CONFINED EAST OF
THE MISSISSIPPI RIVER...THEN REDUCES TO JUST 20 PERCENT ON SATURDAY.
REGARDING TEMPERATURES...TRICKY AS WELL...THOUGH FRIDAY LOOKS TO
BE THE COOLEST DAY POTENTIALLY WITH MORE CLOUDS AND HIGHER
PRECIPITATION CHANCES. MODERATING TEMPERATURES TO NEAR NORMAL BY
SUNDAY WITH WEAK NORTHWEST TO NEAR ZONAL FLOW EXPECTED. GOING INTO
EARLY NEXT WEEK...ANOTHER DIGGING UPPER TROUGH WITH SURFACE FRONT
LEADS TO LOW END RAIN CHANCES AND COOLER TEMPERATURES FOR MONDAY
INTO MONDAY NIGHT. PLENTY OF UNCERTAINTY EXISTS TOO ON THIS
DIGGING UPPER TROUGH.
&&
.AVIATION...TODAY INTO WEDNESDAY
620 AM CDT TUE SEP 11 2012
THE TIGHT PRESSURE GRADIENT WILL REMAIN OVER THE AREA TODAY...THEN
SLACKEN TONIGHT AS A COLD FRONT APPROACHES FROM THE WEST. LOW LEVEL
WIND SHEAR WILL REMAIN AN ISSUE UNTIL 14-15Z THIS MORNING...WITH
SOUTHWEST WINDS OF 35-40KTS ON TOP OF THE NOCTURNAL INVERSION. WITH
DIURNAL WARMING/MIXING...SOUTH WINDS BY LATE THIS MORNING AND FOR
THIS AFTERNOON WILL MIX/INCREASE INTO THE 15-25KT G25-35KT RANGE.
RIDGE TOP AND HIGHER TERRAIN AREAS LIKE KAUM/KRST WILL SEE THE
HIGHER END OF THE RANGE WHILE MOST RIVER VALLEY LOCATIONS WILL SEE
WIND SPEEDS CLOSER TO THE LOW END OF THE RANGE. WITH A DRY AIRMASS
AHEAD OF THE FRONT...GOOD VFR CONDITIONS ARE EXPECTED THRU TODAY/
TONIGHT.
THE FRONT WILL PUSH ACROSS THE AREA WED WITH THE MAIN INCREASE OF
MOISTURE AND LIFT BEHIND THE FRONT. CLOUDS WILL GRADUALLY INCREASE/
LOWER THRU THE DAY WED WITH SOME -SHRA MOVING INTO THE TAF SITES FOR
THE AFTERNOON.
&&
.CLIMATE...TODAY
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
319 AM CDT TUE SEP 11 2012
CRITICAL FIRE WEATHER CONDITIONS REMAIN ON TAP FROM LATE THIS
MORNING THROUGH THIS EVENING ACROSS PORTIONS OF SOUTHEAST MINNESOTA
AND NORTHEAST IOWA. SOUTH TO SOUTHWEST WINDS OF 20 TO 25 MPH WITH
GUSTS OF 30 TO 40 MPH...AND RELATIVE HUMIDITY VALUES OF 20 TO
25 PERCENT ARE EXPECTED...ESPECIALLY DURING THE AFTERNOON HOURS. THE
COMBINATION OF STRONG WINDS AND LOW RH VALUES WILL PRODUCE DANGER
CONDITIONS FOR WILDFIRES. THE RED FLAG WARNING REMAINS IN EFFECT
FROM OLMSTED COUNTY TO CHICKASAW COUNTY WESTWARD. THE WINDS WILL
SUBSIDE LATE TUESDAY EVENING AS A COLD FRONT APPROACHES THE AREA.
HOWEVER...THE COLD FRONT WILL RESULT IN A WIND SHIFT...WITH WINDS
SWITCHING TO THE NORTHWEST. CONDITIONS SHOULD IMPROVE THROUGH THE
NIGHT INTO EARLY WEDNESDAY MORNING AS THE PRESSURE GRADIENT
WEAKENS...TEMPERATURES COOL AND PRECIPITATION EVENTUALLY DEVELOPS.
THROUGH COORDINATION WITH LOCAL FIRE WEATHER PARTNERS
YESTERDAY...LOCATIONS NEAR AND EAST OF THE MISSISSIPPI RIVER HAVE
NOT BEEN INCLUDED IN ANY FIRE WEATHER HEADLINES BECAUSE OF RECENT
RAINS AND FUELS NOT CONDUCIVE TO EXPLOSIVE FIRE GROWTH. SOME DRY
AREAS WILL HAVE TO BE WATCHED CLOSELY...ESPECIALLY SOUTH FACING
SLOPES AND SANDY AREAS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
319 AM CDT TUE SEP 11 2012
WI...NONE.
MN...RED FLAG WARNING FROM 11 AM THIS MORNING TO 9 PM CDT THIS
EVENING FOR MNZ086-087-094-095.
IA...RED FLAG WARNING FROM 11 AM THIS MORNING TO 9 PM CDT THIS
EVENING FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...AJ
LONG TERM...ZT
AVIATION.......RIECK
CLIMATE........BOYNE
FIRE WEATHER...WETENKAMP/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
319 AM CDT TUE SEP 11 2012
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
319 AM CDT TUE SEP 11 2012
MAIN FORECAST CONCERNS ARE ON FIRE WEATHER TODAY...THEN
PRECIPITATION CHANCES AND TRENDS WEDNESDAY THROUGH THURSDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED DEEP TROUGHING OVER SOUTHWEST CANADA INTO THE PACIFIC
NORTHWEST AND RIDGING DOWNSTREAM FROM THE CENTRAL PLAINS INTO THE
WESTERN GREAT LAKES REGION. SHORTWAVES OF NOTE INCLUDE ONE OVER
NORTHWEST SOUTH DAKOTA...THEN A COMPLEX OF THEM IN THE MONSOONAL
MOISTURE ACROSS THE DESERT SOUTHWEST. ASSOCIATED WITH THE SOUTH
DAKOTA SHORTWAVE IS A SURFACE LOW JUST NORTH OF PIERRE. A TIGHT
PRESSURE GRADIENT EXISTS AHEAD OF THIS LOW INTO THE FORECAST
AREA...RESULTING IN BREEZY SOUTH WINDS. THESE WINDS HAVE KEPT
TEMPERATURES UP IN THE MID 50S TO MID 60S. HIGHER ALOFT...AT
850MB...PROFILER DATA SHOWED A SOUTHWEST 35-50 KT JET EXTENDING
FROM THE CENTRAL PLAINS INTO THE FORECAST AREA...ADVECTING WARM
AIR NORTHEASTWARD. 850MB TEMPS HAVE CLIMBED TO 18-22C PER RAP
ANALYSIS...COMPARED TO 00Z RAOBS WHICH WERE BETWEEN 16-18C.
AIRMASS ALSO REMAINS QUITE DRY ACROSS THE CENTRAL PLAINS INTO THE
FORECAST AREA...NOTED BY GOES SOUNDER PRECIPITABLE WATER VALUES OF
0.5-0.6 INCHES OR 60 PERCENT OF NORMAL. ALSO REFLECTIVE OF THE DRY
AIR WAS THE 00Z MPX SOUNDING WHICH HAD DEWPOINT DEPRESSIONS OF 15C
OR MORE FROM THE SURFACE TO 350MB. THE 00Z OAX SOUNDING WAS EVEN
DRIER. SATELLITE IMAGERY DEPICTING ONLY A LITTLE CIRRUS OVER THE
FORECAST AREA.
TODAY AND TONIGHT...MODELS TAKE THE DEEP SOUTHWEST CANADA TROUGH
EASTWARD INTO SOUTH CENTRAL CANADA BY 12Z WEDNESDAY. AS THIS TROUGH
PUSHES EAST...IT WILL PICK UP THE SHORTWAVE AND SURFACE LOW IN SOUTH
DAKOTA...LIFTING THEM INTO NORTHERN ONTARIO. THE ASSOCIATED COLD
FRONT IS TRENDING SLIGHTLY FASTER...NOW PROGGED TO REACH AROUND LA
CROSSE WI AT 12Z WEDNESDAY. THE WARM AIR SURGE AHEAD OF THE FRONT
CONTINUES TODAY WITH 850MB TEMPS PROGGED TO TOP OUT AT 20-22C FOR
18Z. THESE ARE NEAR 2 STANDARD DEVIATIONS ABOVE NORMAL. PLENTY OF
DRY AIR REMAINS...AND WITH 925MB SOUTHWEST WINDS OF 25-30 KT
PROMOTING MIXING AS WELL AS PLENTY OF SUN OUTSIDE OF SOME CIRRUS
LATE IN THE DAY...SHOULD HAVE NO PROBLEM MIXING UP TO THOSE 850MB
TEMPS. THUS...ANTICIPATING HIGHS SIMILAR TO THE PREVIOUS
FORECASTS...FROM THE MID 80S TO LOW 90S. GIVEN THE DRY AIR...BREEZY
CONDITIONS AND WARM TEMPERATURES...CRITICAL FIRE WEATHER CONDITIONS
ARE LIKELY. SEE FIRE WEATHER DISCUSSION FOR MORE DETAILS. FOR
TONIGHT...ALTHOUGH THE FRONT IS MOVING IN SLIGHTLY FASTER...ALL THE
FRONTOGENETIC FORCING AND MOISTURE STILL REMAINS NORTHWEST OF THE
FORECAST AREA. THEREFORE...EXPECTING DRY CONDITIONS AND ONLY A
GRADUAL INCREASE IN CLOUDS. WARM NIGHT ON TAP GIVEN WARM START
AND BREEZY WINDS AHEAD OF THE FRONT. MOST LOCATIONS SHOULD SEE LOWS
IN THE 60S.
WEDNESDAY AND WEDNESDAY NIGHT...ON THE WEST SIDE OF THE DEEP
SOUTHWEST CANADA TROUGH...MODELS ARE IN GOOD AGREEMENT DROPPING A
POTENT SHORTWAVE DOWN INTO THE NORTHERN PLAINS BY 12Z THURSDAY. THIS
SHORTWAVE LOOKS TO HELP KICK OUT ALL OF THE MONSOONAL SHORTWAVES...
EJECTING THEM NORTHEAST ACROSS THE FORECAST AREA. IT APPEARS A
COMBINATION OF THESE VARIOUS SHORTWAVES...ALONG WITH THE POTENT
SHORTWAVE TROUGH...WILL HELP TO KEEP THE COLD FRONT THAT IS NEAR LA
CROSSE AT 12Z WEDNESDAY MOVING TO THE EAST. OF INTEREST...THOUGH...
IS THE FORCING BEHIND THIS COLD FRONT. MODELS DEPICT AN 80-120 KT
JET AT THE TROPOPAUSE PERSISTING BOTH WEDNESDAY AND WEDNESDAY NIGHT
FROM CENTRAL MINNESOTA INTO NORTHERN ONTARIO...PLACING THE FORECAST
AREA IN THE RIGHT ENTRANCE REGION FOR UPPER LEVEL DIVERGENCE. LOWER
IN THE TROPOSPHERE...PLENTY OF LOW TO MID LEVEL FRONTOGENESIS
EXISTS...THOUGH THERE ARE SOME DIFFERENCES IN THE STRENGTH. FOR
EXAMPLE...THE 11.00Z NAM/REGIONAL CANADIAN ARE QUITE A BIT WEAKER
THAN THE 11.00Z GFS/UKMET AND AS SUCH IS A LOT LIGHTER WHEN IT COMES
TO ITS QPF FORECAST. IN FACT...THE 11.00Z NAM DEPICTS VERY LITTLE
RAIN FOR LOCATIONS NORTH OF I-90. CERTAINLY PLENTY OF MOISTURE
EXISTS WITH BOTH THE 11.00Z NAM AND GFS SHOWING AN AXIS OF 1-1.4
INCHES OF PRECIPITABLE WATER WHERE THE FRONTOGENESIS IS. GIVEN ALL
THE FORCING...WOULD HAVE TO THINK A WETTER SOLUTION IS MORE LIKELY.
SREF PROBABILITIES DEPICTING SOME SIMILAR UNCERTAINTY WITH HIGHER
PROBABILITIES OF PRECIPITATION SOUTH OF I-90. WILL TAILOR FORECAST
THIS WAY UNTIL MODELS CAN GET INTO BETTER AGREEMENT. DID REMOVE
THUNDER AS LAPSE RATES UNDER THE FRONTOGENETICAL BAND ARE MAINLY
MOIST-ADIABATIC. THERE IS SOME NEGATIVE EPV RESULTING FROM SLANTWISE
INSTABILITY...SO A COUPLE LIGHTNING STRIKES CANNOT BE RULED OUT.
HOWEVER...MENTIONING ISOLATED THUNDER FOR A WIDESPREAD AREA SEEMS
TOO HIGH OF A PROBABILITY. TEMPERATURES ARE QUITE TRICKY...SINCE
WHERE IT RAINS READINGS WILL BE HELD DOWN DUE TO EVAPORATIVE
COOLING. CERTAINLY WITH THE FASTER FRONT AND INCREASING CLOUDS
THROUGH THE DAY WEDNESDAY...HAVE HAD TO COOL HIGHS DOWN. FOR
NOW...HAVE TAKEN A BLEND OF GUIDANCE FOR BOTH HIGHS AND LOWS...WITH
A FALLING TEMP TREND IN THE AFTERNOON FOR THE PRECIPITATION THAT
DEVELOPS.
THURSDAY AND THURSDAY NIGHT...SOME DIFFERENCES EXIST WITH THE
HANDLING OF THE POTENT TROUGH DROPPING INTO THE NORTHERN PLAINS
THURSDAY MORNING. THE 11.00Z NAM IS AN OUTLIER...TAKING THE TROUGH
EAST TO LAKE SUPERIOR THURSDAY NIGHT. ALL OTHER MODELS
(GFS...ECMWF...UKMET...CANADIAN) HAVE THE TROUGH DIGGING DOWN
TOWARDS IOWA AND CLOSING OFF AS AN UPPER LOW. WILL FOLLOW THIS
GROUP...THOUGH EVEN WITHIN THESE THERE ARE ISSUES...MAINLY
PERTAINING TO HOW DEEP THE UPPER LOW BECOMES. FOR EXAMPLE...THE
DEEPEST 11.00Z CANADIAN PRODUCES A WAVE ALONG THE COLD FRONT...
CAUSING A DEFORMATION/FRONTOGENESIS AREA TO PERSIST OVER EASTERN
IOWA INTO THE FORECAST AREA THROUGH THE ENTIRE PERIOD. AS SUCH...THE
CANADIAN KEEPS THE AREA IN MODERATE TO HEAVY RAIN. THERE HAVE BEEN
PAST ECMWF AND GFS RUNS THAT HAVE SUGGESTED THIS SCENARIO...BUT THE
LATEST 11.00Z GFS AND ECMWF SUGGEST THE FRONTOGENESIS ZONE WILL BE
ABLE TO CONTINUE PUSHING EASTWARD AND NEARLY OUT OF THE AREA BY 12Z
FRIDAY. FOR NOW WILL LEAN TOWARDS THE GFS/ECMWF CONSENSUS BEING IN
THE MIDDLE OF THE NAM/CANADIAN EXTREMES...BUT REALIZE THIS PORTION
OF THE FORECAST HAS SOME UNCERTAINTY. ONE THING THAT DOES SEEM SURE
IS THAT THE SOUTHEASTERN HALF OF THE FORECAST AREA WILL SEE RAIN
THURSDAY WITH THE FRONTOGENESIS ZONE IN PLACE THERE BY ALL MODELS.
THUS...PRECIPITATION CHANCES RANGE FROM 70-90 THERE. LOWER CHANCES
OF PRECIPITATION EXIST ELSEWHERE WITH TIMING ISSUES OF THE
FRONTOGENESIS ZONE MOVING OFF. ALTHOUGH MOST MODELS HAVE
PRECIPITATION MOVING OUT OF THE FORECAST AREA THURSDAY NIGHT...
KEEPING AT LEAST A 20 PERCENT CHANCE EVERYWHERE TO ACCOUNT FOR THE
CANADIAN AND PREVIOUS GFS/ECMWF RUNS. MUCH COOLER TEMPERATURES
ANTICIPATED DURING THIS PERIOD...DUE TO A COMBINATION OF COLD
ADVECTION BEHIND THE FRONT KNOCKING 850MB TEMPS DOWN TO 6-8C...AS
WELL AS EVAPORATIVE/DYNAMIC COOLING WHERE IT IS RAINING. POTENTIAL
EXISTS FOR HIGHS ON THURSDAY IN SAY CRAWFORD COUNTY TO NOT GET ABOVE
60.
.LONG TERM...FRIDAY THROUGH MONDAY NIGHT
319 AM CDT TUE SEP 11 2012
FORECAST DURING THIS PERIOD HIGHLY DEPENDENT ON THE EVOLUTION OF THE
UPPER LEVEL LOW THAT IS EXPECTED TO BECOME CLOSED OFF DURING THE DAY
ON FRIDAY SOMEWHERE ACROSS THE UPPER MIDWEST...WITH THE POTENTIAL TO
LINGER INTO THE FIRST PART OF THE UPCOMING WEEKEND. BY 12Z
FRIDAY...SIGNIFICANT MODEL SPREAD IN LOCATION/STRENGTH OF THE UPPER
LEVEL FEATURE. THE 11.00Z GFS WAS MORE PROGRESSIVE WITH THE
SYSTEM...PUSHING IT QUICKLY EASTWARD BY 12Z SATURDAY SUCH THAT THE
FORECAST AREA WOULD BE DRY. MEANWHILE THE 10.12Z ECMWF AND 11.00Z
CANADIAN WERE STRONGER/SLOWER SOLUTIONS...WHICH PIVOTED MORE
ACROSS THE FORECAST AREA. OF NOTE WAS THE 11.00Z CANADIAN WHICH
DEPICTED SEVERAL DEFORMATION RAIN BANDS FRIDAY NIGHT INTO SATURDAY
RESULTING IN A LARGE SWATH OF MODERATE TO HEAVY RAINFALL ACROSS
PORTIONS OF THE AREA. TO ADD TO THE UNCERTAINTY...THE LATEST
11.00Z ECMWF CAME IN MUCH FASTER THAN ALL GUIDANCE AND QUITE
DIFFERENT FROM ITS PREVIOUS RUN. THIS SOLUTION WOULD MEAN MOST OF
FRIDAY INTO THE WEEKEND THE FORECAST AREA WOULD BE DRY WITH NEAR
NORMAL TEMPERATURES. 11.00Z GFS ENSEMBLES REFLECT THE SAME
UNCERTAINTY ON THE UPPER LOW DEPTH/TRACK THAT THE INDIVIDUAL
MODELS SHOW.
GIVEN THE LARGE VARIABILITY IN SOLUTIONS...AND POOR RUN-TO-RUN MODEL
CONSISTENCY...A MODEL CONSENSUS IS APPROPRIATE WHICH KEEPS
HIGHER PRECIPITATIONS CHANCES FRIDAY/FRIDAY NIGHT CONFINED EAST OF
THE MISSISSIPPI RIVER...THEN REDUCES TO JUST 20 PERCENT ON SATURDAY.
REGARDING TEMPERATURES...TRICKY AS WELL...THOUGH FRIDAY LOOKS TO
BE THE COOLEST DAY POTENTIALLY WITH MORE CLOUDS AND HIGHER
PRECIPITATION CHANCES. MODERATING TEMPERATURES TO NEAR NORMAL BY
SUNDAY WITH WEAK NORTHWEST TO NEAR ZONAL FLOW EXPECTED. GOING INTO
EARLY NEXT WEEK...ANOTHER DIGGING UPPER TROUGH WITH SURFACE FRONT
LEADS TO LOW END RAIN CHANCES AND COOLER TEMPERATURES FOR MONDAY
INTO MONDAY NIGHT. PLENTY OF UNCERTAINTY EXISTS TOO ON THIS
DIGGING UPPER TROUGH.
&&
.AVIATION...
1100 PM CDT MON SEP 10 2012
TIGHT PRESSURE GRADIENT WILL CONTINUE THROUGH TUESDAY...WITH SOME
SLACKENING AS A COLD FRONT STARTS TO PUSH IN FROM THE WEST TUE
NIGHT. TUE AFTERNOON GUSTS OF 30+ KTS ARE LIKELY. MEANWHILE FOR THE
OVERNIGHT...WINDS OFF THE SFC WILL STAY STRONG TONIGHT...RESULTING
IN SOME LLWS CONCERNS. 2 KFT WINDS OF 45 TO 50 KTS ARE EXPECTED FROM
THROUGH ABOUT 15Z TUE. LLWS IS HIGHLIGHTED IN THE TAFS FOR THE
OVERNIGHT HOURS...AND WILL CONTINUE THIS MENTION.
THE FRONT SLOWS UP AS IT MOVES OVER THE UPPER MISSISSIPPI
RIVER...PROBABLY NOT PUSHING EAST OF KRST/KLSE UNTIL LATE TUE-WED.
THERE WILL BE SOME -SHRA WITH THE BOUNDARY...PERHAPS AN ISOLD
TS...BUT THE BETTER FORCING/SATURATION LIES POST FRONT...AND SO WILL
THE PCPN CHANCES. THE POTENTIAL FOR MVFR CIGS LIKELY HOLDS OFF UNTIL
WED NIGHT.
&&
.CLIMATE...TODAY
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
319 AM CDT TUE SEP 11 2012
CRITICAL FIRE WEATHER CONDITIONS REMAIN ON TAP FROM LATE THIS
MORNING THROUGH THIS EVENING ACROSS PORTIONS OF SOUTHEAST MINNESOTA
AND NORTHEAST IOWA. SOUTH TO SOUTHWEST WINDS OF 20 TO 25 MPH WITH
GUSTS OF 30 TO 40 MPH...AND RELATIVE HUMIDITY VALUES OF 20 TO
25 PERCENT ARE EXPECTED...ESPECIALLY DURING THE AFTERNOON HOURS. THE
COMBINATION OF STRONG WINDS AND LOW RH VALUES WILL PRODUCE DANGER
CONDITIONS FOR WILDFIRES. THE RED FLAG WARNING REMAINS IN EFFECT
FROM OLMSTED COUNTY TO CHICKASAW COUNTY WESTWARD. THE WINDS WILL
SUBSIDE LATE TUESDAY EVENING AS A COLD FRONT APPROACHES THE AREA.
HOWEVER...THE COLD FRONT WILL RESULT IN A WIND SHIFT...WITH WINDS
SWITCHING TO THE NORTHWEST. CONDITIONS SHOULD IMPROVE THROUGH THE
NIGHT INTO EARLY WEDNESDAY MORNING AS THE PRESSURE GRADIENT
WEAKENS...TEMPERATURES COOL AND PRECIPITATION EVENTUALLY DEVELOPS.
THROUGH COORDINATION WITH LOCAL FIRE WEATHER PARTNERS
YESTERDAY...LOCATIONS NEAR AND EAST OF THE MISSISSIPPI RIVER HAVE
NOT BEEN INCLUDED IN ANY FIRE WEATHER HEADLINES BECAUSE OF RECENT
RAINS AND FUELS NOT CONDUCIVE TO EXPLOSIVE FIRE GROWTH. SOME DRY
AREAS WILL HAVE TO BE WATCHED CLOSELY...ESPECIALLY SOUTH FACING
SLOPES AND SANDY AREAS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
319 AM CDT TUE SEP 11 2012
WI...NONE.
MN...RED FLAG WARNING FROM 11 AM THIS MORNING TO 9 PM CDT THIS
EVENING FOR MNZ086-087-094-095.
IA...RED FLAG WARNING FROM 11 AM THIS MORNING TO 9 PM CDT THIS
EVENING FOR IAZ008-009-018-019.
&&
$$
SHORT TERM...AJ
LONG TERM...ZT
AVIATION.......RIECK
CLIMATE........BOYNE
FIRE WEATHER...WETENKAMP/AJ
AREA FORECAST DISCUSSION
NWS WICHITA KS
1147 PM CDT WED SEP 12 2012
.AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
AREAS OF RAIN WILL CONTINUE TO GRADUALLY SHIFT SOUTHEAST
OVERNIGHT...GETTING INTO THE KHUT-KICT BY 09-12Z...AS A STRONG
COLD FRONT SETTLES SOUTHEAST OVER SOUTHEAST KS. STRONG
NORTH/NORTHEAST WINDS WILL PREVAIL IN WAKE OF THE FRONT...AND COLD
ADVECTION WILL RESULT IN MVFR CIGS BELOW 2000 FT AGL...WITH PATCHY
IFR OVER MAINLY CENTRAL KS. RAIN CHANCES AND LOWER CIGS WILL
CONTINUE THROUGH THURSDAY FOR PRIMARILY KHUT-KICT.
ADK
&&
.PREV DISCUSSION... /ISSUED 938 PM CDT WED SEP 12 2012/
UPDATE...
STRONG COLD FRONT CONTINUES TO SURGE SOUTHEAST ACROSS THE FORECAST
AREA...QUITE A BIT FASTER THAN OPERATIONAL MODEL PROGS. FELT HRRR
AND RUC13 HAD THE BEST HANDLE ON THE SHORT-TERM TRENDS.
INITIAL ROUND OF SHOWERS/THUNDERSTORMS CURRENTLY EXITING OVER
EAST-CENTRAL KANSAS IS ASSOCIATED WITH THE SURFACE-850MB PORTION
OF THE COLD FRONT. THE MORE EXPANSIVE AREA OF PRECIPITATION WILL
CONTINUE TO SLOWLY TRANSITION SOUTHEAST INTO CENTRAL AND
EVENTUALLY SOUTH-CENTRAL KS AS THE NIGHT PROGRESSES. INSTABILITY
IS LACKING...SO NOT ANTICIPATING WIDESPREAD HEAVY RAIN...ALTHOUGH
ISOLATED LOCATIONS COULD APPROACH ONE-HALF INCH THROUGH SUNRISE.
WIDESPREAD RAINFALL AMOUNTS OF ONE/TWO-TENTHS OF AN INCH SEEMS
REASONABLE OVERNIGHT.
EXPECTING RAIN TO CONTINUE SHIFTING SLOWLY SOUTH THROUGH THE DAY
THURSDAY...AFFECTING SOUTH-CENTRAL/SOUTHEAST KS ALL DAY. LATEST
NAM IS NOW HINTING AT MID-LEVEL BAROCLINIC ZONE LINGERING A BIT
LONGER...WHICH COULD RESULT IN WIDESPREAD RAIN LINGERING OVER
SOUTHERN KANSAS THROUGH THURSDAY NIGHT.
ADK
PREV DISCUSSION... /ISSUED 649 PM CDT WED SEP 12 2012/
AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
WIDESPREAD RAIN/SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS WILL
GRADUALLY INCREASE FROM THE NORTHWEST THIS EVENING THROUGH TONIGHT
FOR ALL SITES EXCEPT KCNU...AS A STRONG COLD FRONT SURGES SOUTH
AND AN ASSOCIATED UPPER LEVEL TROUGH APPROACHES FROM THE
NORTHWEST. THUNDER CHANCES WILL BE GREATEST THIS EVENING FOR
KHUT-KSLN. STRONG/GUSTY NORTH WINDS WILL PREVAIL IMMEDIATELY
BEHIND THE COLD FRONT AS IT SURGES SOUTHEAST. ADDITIONALLY...CIGS
SHOULD GO MVFR BELOW 2000 FT AGL FOR ALL SITES EXCEPT KCNU
TONIGHT...WITH SCATTERED IFR CIGS FOR MAINLY KRSL-KSLN-KHUT.
ADK
PREV DISCUSSION... /ISSUED 318 PM CDT WED SEP 12 2012/
DISCUSSION...
MAIN FORECAST CHALLENGES ARE THE TIMING OF THE COLD FRONTAL PASSAGE
TONIGHT AND THE ASSOCIATED PRECIPITATION TONIGHT AND TOMORROW.
SYNOPSIS:
THE UPPER TROUGH AXIS IS SITUATED ACROSS THE INTER-MOUNTAIN WEST AND
IS SWINGING SOUTHEASTWARD TOWARD THE CENTRAL PLAINS. THIS WAVE WILL
BE THE MAIN WEATHER PRODUCER FOR THE NEXT FEW DAYS. THE SURFACE LOW
AND ASSOCIATED FRONT IS MOVING ACROSS THE CENTRAL PLAINS. IT HAS
SLOWED/STALLED OUT ACROSS CENTRAL KANSAS THIS MORNING/AFTERNOON.
THE WIND SHIFT IS JUST KNOCKING ON KRSL`S DOOR AS OF 3PM. SCATTERED
LIGHT SHOWERS THIS MORNING MOVED OFF TO THE NORTHEAST LEAVING MOSTLY
CLEAR SKIES...THAT IN COMBINATION WITH STOUT SOUTHERLY WINDS HAVE
ALLOWED TEMPS TO RISE INTO THE LOW TO MID 90S ACROSS MUCH OF THE
AREA...EXCEPT NEAREST THE FRONT. HOWEVER...SCATTERED MID-LEVEL
CLOUDS HAVE BEGUN TO DEVELOP OUT AHEAD OF THE SURFACE FRONT AND WILL
BE THE CONCERN FOR THIS AFTERNOON/EARLY EVENING.
TONIGHT - THURSDAY:
THE LATEST HIGHER RESOLUTION MODEL GUIDANCE (NAM/HRRR/RUC) CONTINUES
TO INDICATE SHOWER/THUNDERSTORM DEVELOPMENT AHEAD OF AND WITH THE
FRONT AS IT MOVES SOUTHWARD THIS EVENING. HAVE CUT BACK ON POPS
THROUGH 03Z THURSDAY OVER CENTRAL KANSAS...AND INCREASE IT GREATLY
FROM 03Z ON THROUGH THE NIGHT. INSTABILITY IS MARGINAL...BUT
INCREASES IN THE WARM SECTOR TOWARDS 00Z THURSDAY. SEVERE
THUNDERSTORMS ARE NOT EXPECTED...BUT SOME STRONGER STORMS COULD
DEVELOP IN THE MODEST CAPE/MINIMAL SHEAR REGION AHEAD OF THE FRONT.
THE MAIN CONCERN WILL BE ISOLATED STRONG WIND GUSTS. AS DRY AIR
FILTERS IN...INSTABILITY WILL BE ALL BUT SQUASHED.
THE FRONT IS EXPECTED TO MOVE SOUTHEAST FROM KRSL TO KICT AROUND
03-05Z AND THEN ON TO KCNU BY 10-12Z. HIGH PRESSURE HAS BUILT IN
BEHIND THE FRONT...INCREASING THE PRESSURE GRADIENT. AS THE FRONT
MOVES THROUGH WINDS WILL FLIRT WITH THE 30MPH WIND ADVISORY
CRITERIA. OBSERVING DAYTIME TRENDS...WINDS APPROACHED 30MPH...BUT DID
NOT EXCEED FOR LONG PERIODS OF TIME. REGARDLESS IT WILL BE WINDY
OUT OF THE NORTHEAST OVERNIGHT.
POST FRONTAL PRECIPITATION WILL CONTINUE THROUGH THE DAY THURSDAY
ENDING FROM NORTHWEST TO SOUTHEAST BY THURSDAY AFTERNOON.
WIDESPREAD PRECIPITATION ACCUMULATIONS OF 0.5 INCH TO 1 INCH ARE
EXPECTED WITH SOME AREAS SEEING HIGHER AMOUNTS. TEMPERATURES WILL
BE SIGNIFICANTLY COOLER BEHIND THE FRONT THURSDAY WITH AREAS UNDER
CLOUD COVER AND PRECIPITATION NOT MAKING IT OUT OF THE 60S. WHERE
THE SUN BREAKS OUT TEMPS WILL IMPROVE TO THE LOW 70S.
FRIDAY - SUNDAY:
THE WAVE THAT MOVES THROUGH WILL LEAVE BEHIND SOME ENERGY THAT WILL
MOVE IN FROM THE FOUR CORNERS REGION...TX/OK PANHANDLES AND WILL
IMPACT THE FORECAST INTO THE WEEKEND. IN ADDITION TO THE COOL
AIRMASS BEHIND THE FRONT...THIS ADDITIONAL SYSTEM WILL KEEP OKLAHOMA
AND PORTIONS OF SOUTHERN KANSAS CLOUDY AND COOL. TEMPS WILL BE IN
THE 70S WITH SOME AREAS POSSIBLY COOLER. THE LIFT ASSOCIATED WITH
THIS PV ANOMALY WILL ALSO KEEP PRECIPITATION CHANCES FOR SOUTHERN
KANSAS THROUGH FRIDAY AND SATURDAY. CONFIDENCE IS NOT HIGH ON HOW
EXPANSIVE THIS PRECIP WILL BE.
MONDAY - WEDNESDAY:
THE NEXT MAIN SHORTWAVE WILL KICK THE ENERGY EASTWARD THAT WILL
IMPACT THE REGION OVER THE WEEKEND. THIS WAVE WILL AGAIN PUSH A
FRONT THROUGH THE AREA WITH ADDITIONAL PRECIPITATION CHANCES FOR
EARLY NEXT WEEK. THIS FRONT IS NOT QUITE AS POTENT AND HAS MUCH
LESS MOISTURE TO WORK WITH THAN THE SYSTEM FOR TONIGHT/THURSDAY.
SHOWERS/THUNDERSTORMS ARE POSSIBLE...BUT CONFIDENCE IS LACKING ON
HOW WIDESPREAD THE RAIN WILL BE FOR THE AREA. TEMPERATURES FOR THE
NEXT WORKWEEK WILL BE IN THE 70S AND LOW 80S...SEASONAL FOR MID
SEPTEMBER.
BILLINGS
AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
FOCUS IS ON THE TIMING OF THE FRONT AND ASSOCIATED PRECIPITATION/
CEILINGS. THERE IS GOOD AGREEMENT IN SHORT RANGE MODELS FOR SOME
RAIN SHOWERS/THUNDERSTORMS TO BREAK OUT AHEAD OF THE FRONT FROM
MID LEVEL DECK...WHICH WILL BE CLOSE TO KHUT/KSLN AND LIKELY CATCH
KICT LATER THIS AFTERNOON. THE MAIN SHOW WILL OCCUR TONIGHT WITH
PRECIPITATION CHANCES INCREASING AT MOST SITES DURING THE NIGHT
AND LINGERING INTO THE MORNING. ANTICIPATE MVFR CEILINGS TO OCCUR
IN THE VICINITY OF MORE WIDESPREAD RAIN. VERY GUSTY NORTH WINDS
ARE EXPECTED JUST BEHIND THE FRONT. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 55 64 51 74 / 60 70 30 10
HUTCHINSON 54 62 46 74 / 90 80 10 10
NEWTON 55 64 48 73 / 70 80 20 10
ELDORADO 56 65 51 75 / 40 80 30 10
WINFIELD-KWLD 59 68 54 74 / 40 90 50 20
RUSSELL 53 69 43 75 / 100 50 10 10
GREAT BEND 53 66 44 73 / 100 70 10 10
SALINA 53 66 45 75 / 100 70 10 10
MCPHERSON 54 63 46 74 / 100 70 10 10
COFFEYVILLE 62 75 55 77 / 20 50 50 30
CHANUTE 61 69 54 75 / 20 70 40 20
IOLA 60 68 54 74 / 20 70 30 20
PARSONS-KPPF 62 72 55 76 / 20 50 50 30
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DULUTH MN
410 AM CDT THU SEP 13 2012
.SHORT TERM..CONVEYOR BELT OF UPPER LVL MOISTURE CONTINUES TO
MOVE NORTHEAST OVER ERN HALF OF CWA...ASSOCIATED WITH FORWARD
FLANK OF 30H TROF. BDRY LYR FEATURES A CYCLONIC FLOW OF RELATIVELY
DRY AIR UNDERCUTTING MOIST AIR ALOFT. A FEW SPRINKLES OR SHOWERS
ARE POSSIBLE THROUGH EARLY MORNING OVER PRICE COUNTY. WEDGE OF VERY
DRY AIR WITHIN 925/850 LYR HAS ADVECTED INTO AREA FROM TWIN PORTS
SOUTHWEST TO BRD LAKES VICINITY. A SECONDARY COLD FRONT IS LOCATED
OVER CTRL MAN/ONTARIO WITH DECENT LOW LVL THERMAL RIBBON INDICATED
IN RAP 925 ANALYSIS. LARGE MID/UPPER LVL LOW OVER ERN SASK IS
MOVING SE WITH GRADUAL MOISTENING OF LOWER LAYERS ACROSS SRN
MAN/ONTARIO.
TODAY...UPPER LOW OVER SASK WILL TRACK TOWARDS KINL BY EARLY
EVENING. CLOUDS WILL INCREASE WITH SLGT CHC PRECIP NEAR BORDER
THIS AFTN. MAX TEMPS IN NRN LAKE/COOK COUNTIES A BIT ON THE
CHILLY SIDE. STEEPENING LAPSE RATES WITH MID LVL MOISTURE MAY
GENERATE CONSIDERABLE VIRGA TODAY ACROSS NRN HALF OF MN ZONES.
BEST FORCING WILL REMAIN NEAR SECONDARY COLD FRONT NORTH OF THE
BORDER. VERY DEEP MIXING LAYER 0F 8K TO 10K TODAY ACROSS MOST OF
THE CWA SHOULD ALLOW MOMENTUM TRANSFER AND GUSTY WINDS. GUSTS WILL
NOT BE AS HIGH AS YESTERDAY AS CORE OF STRONGER WINDS ALOFT WILL
HAVE SHIFTED EAST OF REGION. ELEVATED FIRE DANGER MAY DEVELOP OVER
SWRN/SCTRL CWA IN THE AREA OF LOWEST RH AND GUSTY WINDS.
TONIGHT...MID LVL LOW MOVES TO ERN LAKE SUPERIOR WITH DEEP LYR
DRYING EXPECTED TO COVER MOST OF CWA BY EARLY FRIDAY. SFC HIGH
WILL MOVE INTO CWA WITH WINDS SUBSIDING. LATEST SREF PLUMES
SUPPORT TEMPS IN LOW/MID 30S RANGE OVER MOST OF CWA INLAND FROM
LAKE SUPERIOR. HAVE ISSUED FROST ADVISORY FOR CWA EXCEPT NSHORE
ZONES...AND ERN MOST WISC ZONES. CLOUD COVERAGE AND MIXING WILL
BE SLOWEST TO LEAVE ERN WISC ZONES. FROST DURATION MAY BE FAIRLY
LIMITED IN MOST LOCATIONS DUE TO INITIAL CLOUD COVERAGE AND WIND.
TOMORROW...VERY PLEASANT WEATHER PATTERN AS SFC/MID LVL RIDGING
PREVAIL FOR MOST OF THE DAY. NEAR CLIMO TEMPS AND ABUNDANT SUNSHINE.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
SFC HIGH PRESSURE AND MID LEVEL RIDGING WILL PREVAIL FRIDAY
RESULTING IN A DRY DAY WITH LIGHT WINDS. A TRANSITION TO WAA AND A
SRLY FLOW IS FOUND FRIDAY NIGHT AS AN ELONGATED H85 TROUGH MOVES
INTO THE LEE OF THE ROCKIES/WESTERN DAKOTAS. THE NORTHLAND REMAINS
SITUATED AHEAD OF THE TROUGH IN THE STRONG WAA SATURDAY...ALLOWING
FOR WELL ABOVE NORMAL TEMPS...IN THE 70S TO AROUND 80...AND GUSTY
SOUTH-SOUTHWEST WINDS. THE LATEST GFS/ECM/GEM ARE SHOWING GOOD
AGREEMENT THAT H85 TEMPS COMMENCE IN THE SINGLE DIGITS FRIDAY
EVENING...REACHING THE MID AND TEENS BY SATURDAY EVENING.
TEMPERATURES WILL BE COOLER ALONG THE NORTH SHORE OF LAKE SUPERIOR
WITH A LIGHT ONSHORE WIND.
THE LONG WAVE TROUGH AND H50 VORT...ACCOMPANIED BY A STRONG SFC COLD
FRONT...WILL SWEEP SOUTHEAST OVER THE REGION SUNDAY NIGHT INTO
MONDAY. THE FROPA WILL BRING RAIN SHOWERS...GUSTY NORTHWEST
WINDS...AND MUCH COOLER TEMPERATURES. HAVE LOWERED HIGHS MONDAY INTO
THE 50S AS A POTENT CAA REGIME WILL LIMIT MUCH WARMING AND KEEP
CLOUDS AND SHOWERS AROUND. LONG TERM MODELS CONTINUE TO SHOW H85
TEMPS FALL INTO THE NEGATIVE SINGLE DIGITS WITH H50 TEMPS
APPROACHING NEGATIVE 30 ACROSS THE BORDERLAND MONDAY NIGHT. THE COLD
TEMPS...STEEP LAPSE RATES...AND H10-H50 THICKNESSES OF 530 DAM
SUPPORT A CHANCE FOR ANY LINGERING RAIN SHOWERS IN THE MN ARROWHEAD
ZONES TO MIX WITH SNOW. HOWEVER...LITTLE OR NO ACCUMULATION IS
EXPECTED.
THE NORTHLAND REMAINS UNDER THE BROAD CYCLONIC FLOW THROUGH THE
REMAINDER OF THE WEEK...KEEPING COOLER TEMPERATURES AND ONGOING
CHANCES FOR SHOWERS THROUGH THE EXTENDED. .
.AVIATION.../06Z TAF ISSUANCE/
HIGH CLOUDS WILL CONTINUE TO STREAM THROUGH THE NORTHLAND
OVERNIGHT...BUT THE CLOUDS WILL GRADUALLY DECREASE. MEANWHILE...A
COLD CORE WILL MOVE TO THE SOUTHEAST ACROSS THE REGION. THIS WILL
RESULT IN SOME LOW TO MID CLOUDS THURSDAY AFTERNOON AND EVENING.
WINDS WILL BE A BIT GUSTY DURING THE DAY...BUT THEN DECREASE QUICKLY
BY THURSDAY EVENING.
.POINT TEMPS/POPS...
DLH 65 37 68 40 / 10 10 0 0
INL 61 34 68 37 / 20 0 0 0
BRD 67 36 72 38 / 10 0 0 0
HYR 66 32 69 36 / 10 10 0 0
ASX 67 39 68 39 / 10 10 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...FROST ADVISORY FROM 2 AM TO 8 AM CDT FRIDAY FOR MNZ010>012-018-
019-025-026-033>038.
WI...FROST ADVISORY FROM 2 AM TO 8 AM CDT FRIDAY FOR WIZ001-002-
006>008.
LS...NONE.
&&
$$
SHORT TERM...CANNON
LONG TERM....GRANING
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
412 AM CDT THU SEP 13 2012
.DISCUSSION...
Short Range (Today through Saturday)...
Primary weather concerns are focused over the next 18 hours. By
sunrise a cold front which entered northwest MO Wednesday evening
will have made it through the entire CWA. A pronounced upper trough
over the Northern and Central Plains will slide east-southeast
through MN/IA/MO today. While there has been little to no
pre-frontal convection multi-layered frontogenesis and isentropic
ascent primarily on the 305K surface have resulted in a sw-ne
oriented band of convection from KS through IA. However, this band
has steadily narrowed and decreased in intensity since midnight.
Have placed a strong emphasis on the 00Z NAM and LSX local WRF which
projected a steady weakening of the frontogenetical forcing as well
as just about eliminating the isentropic ascent by mid morning
today. Radar trends and latest HRRR model output further support
these two models. So, have lowered pops over most areas except the
far northwestern CWA.
Would have lowered them further except for a little fly in the
ointment...layered clouds/scattered convection associated with an
upper low just south of the 4-corners area is being tapped into by
the Plains upper trough. These scattered showers are being lifted
northeast and should see some of this moisture spread into the the
west central CWA by this afternoon...and possibly reaching into
central MO by late afternoon. Have also lowered temperatures within
the expected areas of showers and decent cold air advection.
Weak high pressure will move into the Central Plains and MO on
Friday although some semblance of the upper low will be hanging
around from NM into southern KS. This creates a little uncertainty
as to how far south the clearing will push south as well as the
threat of some showers possibly reaching the far southwestern
counties. Otherwise, looking at some very pleasant weather into the
first part of the weekend.
MJ
Medium Range (Sunday through Wednesday)...
The cutoff low that forms across the southern High Plains this
weekend begins to eject eastward on Sunday, as the southwesterly jet
over the Texas Panhandle strengthens. The resultant wave appears a
bit weaker as it shifts eastward in the latest model runs, but could
still produce some widely scattered precipitation across southern
portions of the CWA on Sunday. Also on Sunday, the next deep trough
across the Northern Plains begins diving southeastward into the
forecast area, beginning the chance of precipitation across our
northwest by Sunday night. Most operational models kick this system
through fairly quickly on Monday, with the exception of the GEM and
a few of the GFS ensemble members, so have cut back precipitation
chances to the south and east on Monday night and Tuesday. Another
front will likely drop through the region sometime in the Wednesday
- Thursday timeframe again next week, and have kept in a chance of
precipitation Wednesday night when most models bring the boundary
through. Temperatures will be primarily below average through the
extended forecast, with little chance for recovery between potent
cold frontal passages.
Laflin
&&
.AVIATION...
For the 06Z TAFs...surface cold front is currently between MCI and
MKC and stretches northeastward into north central Missouri. This
front will continue to push southeast into the MKC and OJC terminals
over the next couple of hours. While there could be a few scattered
showers or even a brief thunderstorm near the front, the bulk of the
rainfall remains well behind the front. This activity is approaching
STJ where occasional MVFR or even IFR restrictions are likely.
This area of rain is still expected to gradually scatter out and
weaken as it spreads southward toward sunrise so that prolonged rain
may not occur as far south as MCI or MKC. However, models indicate
that scattered low clouds in high-end IFR or low-end MVFR may make it
as far south of the KC terminals before scattering and lifting
through mid morning.
Hawblitzel
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1211 AM CDT THU SEP 13 2012
.UPDATE...
ISSUED AT 930 PM CDT WED SEP 12 2012
CURRENT FORECAST LOOKS PRETTY MUCH ON TRACK FOR THE REST OF THE
NIGHT. COLD FRONT IS NOW STRETCHING FROM NEAR DAVENPORT IA
SOUTHWEST TO JUST NORTH OF THE KC METRO AREA. CURRENT RAP FORECAST
HAS IT PUSHING THROUGH KIRKSVILLE AROUND 09Z AND DOWN TO ALONG A
COLUMBIA MO-QUINCY IL LINE BY 12Z. NEW NAM AGREES WITH THIS
POSITION...THO THE TRUE LOW LEVEL BAROCLINICITY LAGS BACK IN
NORTHWEST/NORTH CENTRAL MISSOURI AT 12Z. STILL THINK THE AREA WILL
REMAIN DRY AT LEAST UNTIL THEN...POTENTIALLY INTO MID MORNING
THURSDAY. CURRENT TEMPERATURES ARE WITHIN 1 TO 2 DEGREES OF
FORECAST...SO TEMP TRENDS LOOK ON TRACK AT THIS TIME.
CARNEY
&&
.SHORT TERM...
ISSUED AT 208 PM CDT WED SEP 12 2012
(TONIGHT)
COLD FRONT CURRENTLY STRETCHING FROM SOUTHEAST NEBRASKA TO EASTERN
WISCONSIN WILL CONTINUE TO SLOWLY EDGE ITS WAY SOUTH TONIGHT AND
BE KNOCKING ON THE FAR NORTHERN PORTION OF THE CWA BY 12Z. RAIN
CONTINUES TO BE POST FRONTAL WITH THIS SYSTEM...SO THE FORECAST
REMAINS DRY OVERNIGHT. SOUTHERLY WIND AND INCREASING LOW LEVEL
MOISTURE SHOULD KEEP TEMPERATURES SLIGHTLY ABOVE NORMAL...WITH A
NOD GOING TO THE WARMER MET GUIDANCE.
CVKING
&&
.LONG TERM...
ISSUED AT 344 PM CDT WED SEP 12 2012
(THURSDAY THROUGH WEDNESDAY)
COLD FRONT WILL BE OVER NORTHERN PORTIONS OF FORECAST AREA BY
DAYBREAK THURSDAY MORNING...WITH SHOWERS SPREADING INTO THE
REGION...MAINLY POST FRONTAL. BEST CHANCES WILL BE OVER NORTHEAST
MO/WEST CENTRAL IL DURING THE DAY ON THURSDAY...THEN INCREASE IN
COVERAGE ACROSS REST OF FORECAST AREA THURSDAY EVENING. NOT A LOT OF
INSTABILITY WITH THIS SYSTEM...SO SHOULD BE MOSTLY RAIN/SHOWERS...
THOUGH SOME ISOLATED STORMS NOT OUT OF THE QUESTION FOR CENTRAL MO
THURSDAY AFTERNOON...SO LEFT MENTION IN THERE. MODELS CONTINUE TO BE
A LOT FASTER WITH ENDING THE PCPN...SO HAVE LOWERED POPS AFTER 06Z
FRIDAY AND HAVE PCPN COMING TO AN END AT ALL LOCATIONS BY 18Z FRIDAY.
AS FOR HIGHS ON THURSDAY...WILL BE DEPENDENT ON CLOUD COVER AND PCPN
COVERAGE. FOR NOW SHOULD SEE HIGHS RANGING FROM THE UPPER 60S FAR
NORTH TO THE LOW 80S ALONG AND SOUTH OF I-70. ALSO...WILL BE GOING
WITH A NON DIURNAL TREND...MAINLY FOR NORTHERN PORTIONS OF FORECAST
AREA...WITH HIGH TEMPS IN THE LATE MORNING HOURS...THEN TEMPS STEADY
OR SLOWLY FALLING DURING THE AFTERNOON HOURS.
BY THURSDAY NIGHT...COLDER AIR TO BEGIN FILTERING IN WITH LOWS IN
THE MID 40S TO MID 50S.
WILL SEE MORE FALL LIKE WEATHER ONCE AGAIN THROUGH THE WEEKEND.
HIGHS ON FRIDAY WILL BE IN THE LOW 70S AND IN THE MID 70S ON
SATURDAY. AS FOR LOW TEMPS...WILL SEE ANOTHER COLD NIGHT FRIDAY
NIGHT WITH LOWS IN THE UPPER 40S TO LOW 50S.
STRONG SURFACE RIDGE TO BEGIN MOVING OFF TO THE EAST LATE IN THE
WEEKEND AND INTO EARLY NEXT WEEK WITH TEMPS MODERATING A BIT. HIGHS
WILL BE IN THE UPPER 70S SUNDAY AND MONDAY.
THEN ANOTHER STRONG COLD FRONT TO MOVE INTO THE REGION ON
MONDAY...BRINGING ANOTHER CHANCE FOR SHOWERS AND THUNDERSTORMS
MONDAY AND MONDAY NIGHT. BEHIND THE SYSTEM...COOLER THAN NORMAL
WEATHER TO PERSIST WITH HIGHS IN THE MID 60S TO MID 70S WITH LOWS IN
THE MID 40S BY TUESDAY MORNING.
BYRD
&&
.AVIATION...
ISSUED AT 1210 AM CDT THU SEP 13 2012
VFR CONDITIONS AND LIGHT S FLOW WILL CONTINUE AREAWIDE...AHEAD OF
THE CDFNT...WHICH IS CURRENTLY FROM SERN IA TO NWRN MO. CDFNT
CONTINUES TO RUN A BIT SLOWER THAN ORIGINALLY THOUGHT...AND SHOULD
PUSH TO NEAR A KUIN-KCOU AXIS BETWEEN 11-15Z AND THEN PUSH INTO
THE STL METRO AREA BETWEEN 18-22Z. MODELS HAVE BACKED OFF ON PCPN
POTENTIAL WITH THIS...AS MUCH OF THE UPPER LEVEL SUPPORT MISSES US
TO THE N...LEAVING BEHIND WHAT WILL LIKELY BE A REGION OF SCT SHRA
BEHIND THE CDFNT. MODELS HAVE ALSO BACKED OFF ON THE NON-VFR CIGS
BEHIND THE FRONT...AND THIS MAKES SENSE CONSIDERING HOW THEY ARE
ALSO BACKING OFF ON THE PCPN POTENTIAL...WHICH WOULD BE NEEDED TO
HELP SUSTAIN ANY LO CLOUDS. REMOVED THE HI-END MVFR CIGS IN FAVOR
OF LO-END VFR CIGS FOR THIS ISSUANCE AND WILL NEED TO BE WATCHED
AS LOWER CLOUDS BEHIND CDFNT APPROACH.
SPECIFICS FOR KSTL...VFR AHEAD OF THE CDFNT THRU EARLY AFTERNOON
THURSDAY...TRANSITIONING TO LO-END VFR CIGS BEHIND CDFNT LATER ON
THURSDAY AFTERNOON. PCPN LOOKS SPOTTY AT BEST...AND KEPT VCSH
MENTION FOR NOW BUT WELL BEHIND FROPA.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
408 AM CDT THU SEP 13 2012
.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT. A RELATIVELY QUITE
PATTERN IS EXPECTED OVER THE NEXT FEW DAYS. PRECIPITATION WILL EXIT
THE OUTLOOK AREA THIS MORNING MORNING...AND THIS WILL BEGIN THE
RELATIVELY QUITE WEATHER AS HIGH PRESSURE SLIDES INTO THE REGION
FROM THE WEST.
THE LATEST RUNS OF BOTH THE NAM AND RUC SUGGEST PRECIPITATION ENDING
ACROSS THE CWA BY MID TO LATE MORNING. FURTHERMORE...THE HRRR ALSO
DEPICTS DRY CONDITIONS BY MID MORNING...SO WENT AHEAD AND SPLIT THE
12Z TO 18Z BLOCK INTO TWO 3 HOUR GROUPS TO ACCOUNT FOR THE
PRECIPITATION ENDING EARLIER THAN PREVIOUSLY FORECAST THIS
MORNING.
WITH LIGHT WINDS AND SUBSIDENCE EXPECTED BEHIND THE EXITING
STRATUS...THERE WILL BE A CHANCE FOR SOME PATCHY FOG EARLY THIS
MORNING...ESPECIALLY NORTHWESTERN PARTS OF THE CWA IF ENOUGH
CLEARING CAN OCCUR BEFORE DAYTIME HEATING BEGINS. CONFIDENCE IS NOT
HIGH ENOUGH TO GO WITH A PRE-FIRST PERIOD AS MOST SPOTS SHOULD BE
ABOVE 3 MILES OF VISIBILITY BY 12Z. NOT GOING TO INCLUDE THE
MENTIONING OF FOG AT THIS TIME BUT THOUGHT IT WAS WORTH MENTIONING.
GOING TO LEAVE IT IN THE GRIDS THOUGH.
THE BIGGEST FORECAST CHALLENGE FOR THE REST OF THE SHORT TERM WILL
BE TEMPERATURES. TEMPERATURES ON FRIDAY WERE NOTICEABLY DIFFERENT
THAN PREVIOUSLY FORECAST...WITH HIGHS 3 TO 4 DEGREES WARMER IN MOST
LOCATIONS. FRIDAY MORNING LOW TEMPERATURES WERE ALSO 3 TO 4 DEGREES
WARMER IN MOST LOCATIONS. THE THOUGHT BEHIND THESE HIGHER
TEMPERATURES IS MOST LIKELY GUIDANCE KEYING ON HIGHER DEWPOINTS FROM
THE RECENT RAINFALL...MOSTLY CLEAR SKIES...AND ADIABATIC COMPRESSION
FROM THE WESTERLY WIND COMPONENT. THE LATEST RUN OF THE NAM12 ALSO
DEPICTS WARM AIR ADVECTION AT 850MB AS OPPOSED TO PREVIOUS RUNS...SO
WENT AHEAD AND RAISED TEMPERATURES A FEW DEGREES TO ACCOUNT FOR THIS
WARMER SETUP. THIS WAS THE BIGGEST CHANGE DURING THIS PERIOD.
OVERALL...NEAR SEASONABLE TEMPERATURES AND DRY CONDITIONS WILL BE
EXPERIENCED BOTH FRIDAY AND SATURDAY.
.LONG TERM...SUNDAY THROUGH WEDNESDAY...A BEAUTIFUL END OF THE
WEEKEND APPEARS TO BE ON TAP FOR THE REGION SUNDAY AS SEASONABLY
WARM TEMPERATURES...LIGHT SOUTHERLY WINDS....AND ONLY A FEW HIGH
CLOUDS ARE EXPECTED AHEAD OF AN APPROACHING FRONTAL BOUNDARY. THIS
FRONTAL BOUNDARY WILL BE STEERED ACROSS THE PLAINS SUNDAY NIGHT
THROUGH MONDAY BY AN UPPER LEVEL SHORTWAVE...WITH A MARKEDLY COOLER
AIRMASS EXPECTED IN ITS WAKE AS 850MB TEMPS AREA FORECAST TO DROP
8-10C BEHINDS THIS FRONT. WHILE THERE WILL ALSO BE A CHANCE FOR A
FEW SHOWERS AND EVEN AN ISOLATED THUNDERSTORM LATE SUNDAY NIGHT
THROUGH MONDAY EVENING...THE BEST UPPER LEVEL FORCING APPEARS TO BE
TO DIRECTED THE NORTHEAST OF THE LOCAL AREA IN BOTH LATEST RUNS OF
THE GFS AND EC...AND DECIDED TO TONE DOWN PRECIP CHANCES ACCORDINGLY
OVER THIS TIME PERIOD AS A DEVELOPING UPPER LEVEL RIDGE ACROSS THE
WESTERN STATES APPEARS TO BE SHIFTING THE FOCUS OF THIS SYSTEM AWAY
FROM THE AREA.
THEREAFTER...A GENERALLY NORTHWESTERLY UPPER LEVEL FLOW PATTERN IS
PROGGED TO KEEP MAIN FOCUS OF WEATHER ACROSS THE CENTER OF THE
COUNTRY THROUGH MID WEEK...WITH SEASONABLY COOL TEMPERATURES
EXPECTED AGAIN ON TUESDAY...WITH A BRIEF WARMING TO NEAR OR ABOVE
CLIMO WEDNESDAY...AHEAD OF THE NEXT APPROACHING COLD FRONT. WHILE
MODELS WERE TRYING TO KEY IN ON SOME SMALL CHANCE POPS WITH THIS
NEXT BOUNDARY WED/WED NIGHT...WITH PERSISTENT UPPER LEVEL RIDGE OVER
THE WEST COAST AND CORRESPONDING FOCUS OF STORM TRACK TO OUR
EAST...NOT TO MENTION VERY LIMITED LOW LEVEL MOISTURE...WENT AHEAD
AND REMOVED SMALL CHANCE POPS FROM THE FORECAST WITH THIS SECOND
FRONT MID WEEK IN COORDINATION WITH SURROUNDING OFFICES.
&&
.PREV DISCUSSION... /ISSUED 1229 AM CDT THU SEP 13 2012/
AVIATION...06Z KGRI TAF...AT 05Z...THE BACK EDGE OF THE
PRECIPITATION BAND WAS APPROACHING KGRI IN LATEST RADAR IMAGES.
AS A RESULT...EXPECT MORE STEADY PRECIPITATION TO END AT THE
TERMINAL PRIOR TO 06Z...WITH SHRAS CONTINUING IN THE VICINITY OF
THE TERMINAL FOR THE NEXT COUPLE OF HOURS. ONCE THE PRECIPITATION
BEGINS TO WANE AND SOME BREAKS IN MID LEVEL CLOUD DECK ARE
REALIZED...EXPECT CIGS TO DROP SIGNIFICANTLY AS LOW LEVEL STRATUS
AND SOME PATCHY FOG BEGINS TO FORM AND SPREAD ACROSS THE TERMINAL.
WHILE GUIDANCE IS NOT IN COMPLETE AGREEMENT WITH THE DEVELOPMENT
OF LOW VISIBILITIES WITH PATCHY FOG THIS MORNING...FAIRLY GOOD
AGREEMENT DEVELOPING THE LOW CIGS...SO WENT AHEAD AND INTRODUCED
SOME LIFR CIGS FROM 13/10Z-13/14Z...KEEPING VISIBILITIES IN PATCHY
FOG IN THE MVFR RANGE. ONCE THE SUN RISES AND STRATUS BEGINS TO
BREAK...EXPECT A RETURN TO VFR CONDITIONS BY 13/14Z...WITH LIGHT
WEST TO NORTHWESTERLY WINDS THROUGH THE AFTERNOON HOURS AS AN AREA
OF SURFACE HIGH PRESSURE SINKS SOUTHWARD ACROSS THE REGION.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...GUERRERO
LONG TERM/AVIATION...ROSSI
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1228 AM CDT THU SEP 13 2012
.AVIATION...
CLEARING SKIES OVERNIGHT WITH LIGHT WINDS LESS THAN 10 MILES AN HOUR
ARE EXPECTED OVER WESTERN NEBRASKA AS SURFACE HIGH PRESSURE BUILDS
IN. NO CLEAR FOG SIGNAL SO HAVE LEFT MENTION OUT OF TAFS AT BOTH
KVTN AND KLBF.
&&
.PREV DISCUSSION... /ISSUED 810 PM CDT WED SEP 12 2012/
UPDATE...
SHOWERS HAVE MOVED JUST EAST OF THE FORECAST AREA. HAVE ENDED
PRECIPITATION AND LOWERED POPS. TEMPERATURE FORECAST LOOKS TO BE
ON TRACK IF SKIES CLEAR LATER.
&&
.PREV DISCUSSION... /ISSUED 647 PM CDT WED SEP 12 2012/
AVIATION...
SOME ISOLATED SHOWERS OVER THE NEBRASKA PANHANDLE THIS EVENING
WILL DISSIPATE WITH THE SETTING OF THE SUN. THE MAIN AREA OF
PRECIPITATION IS MOVING INTO CENTRAL NEBRASKA AND IS GENERALLY
EAST OF A KONL TO KIML LINE AND MOVING SLOWLY EAST. MVFR CEILINGS
OVER SOUTHWEST NEBRASKA WILL RISE INTO VFR CATEGORIES AFTER 1303Z.
SKIES CLEARING OUT OVER WESTERN NEBRASKA AFTER 1306Z WITH LIGHT
WINDS AND CLEAR SKIES THURSDAY UNDER SURFACE HIGH PRESSURE.
PREV DISCUSSION... /ISSUED 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.
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...POWER/CDC
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
130 AM EDT THU SEP 13 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER THROUGH THE
END OF THE WORK WEEK. A WEAK AND MOISTURE STARVED COLD FRONT WILL
MOVE ACROSS THE AREA EARLY SATURDAY...THEN DISSIPATE ALTOGETHER
DURING SUNDAY. HIGH PRESSURE RIDGING FROM THE NE STATES WILL
DOMINATE THE WEATHER THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1035 PM WEDNESDAY...CENTER OF SURFACE HIGH PRESSURE TO TRACK
OFFSHORE FROM THE MID-ATLANTIC AND NE STATES OVERNIGHT INTO
THURSDAY. LATEST SAT IMAGERY INDICATES THIN TO OCCASIONALLY OPAQUE
CIRRUS TO OVERSPREAD THE FA FROM THE SW DURING THE OVERNIGHT.
AT THE SAME TIME...EXTRAPOLATION OF THE SC DECK NEARSHORE AND
OFFSHORE FROM THE CAROLINAS USING THE LATEST IR SAT IMAGERY AS THE
INITIAL TIME...WILL MOVE PARTIALLY ONSHORE SOUTH OF THE SC/NC BORDER.
LATEST HRRR MODEL OUTPUT ILLUSTRATES POSSIBLE PCPN ACCOMPANYING THE
SC DECK AS IT REACHES AND MOVES ACROSS THE COASTAL WATERS SOUTH OF
THE NC-SC BORDER. AT THIS POINT...THE DRY AIR ACROSS LAND LOCATIONS
WITHIN THE FA...AND THE SUBSIDENCE ALOFT SHOULD HELP TO PREVENT THE
PCPN FROM MOVING ONSHORE AND INLAND. CURRENT MIN FORECAST LOOKS ON
CUE AND SEE NO REASON TO DETOUR FROM PREVIOUS THINKING.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...HIGH PRESSURE RIDGING BACK FROM CENTER
SHIFTING FURTHER EAST INTO THE ATLANTIC OFF THE NEW ENGLAND COAST ON
THURS INTO EARLY FRI. THIS WILL CONTINUE TO PRODUCE AN E-NE ON SHORE
FLOW. BY FRIDAY...THE HIGH WEAKENS AS IT GETS SQUEEZED OUT BY A
MOISTURE STARVED COLD FRONT MOVING INTO THE CAROLINAS FROM THE
NORTHWEST. THE ON SHORE FLOW MAY PRODUCE SOME PATCHES OF CLOUDS
MOVING IN FROM THE WATERS OVERNIGHT THURS. THE MODELS SHOW PCP WATER
DOWN LESS THAN AN INCH THROUGH THURS AFTN BUT THEN AN INCREASE WITH
THIS ON SHORE FLOW AND APPROACHING COLD FRONT LATE FRI INTO SAT.
THE MID TO UPPER RIDGE SLIPS OFF THE EAST COAST BY FRIDAY AS
TROUGH DEEPENS DOWN THROUGH THE APPALACHIANS. THIS WILL PRODUCE A
RETURN FLOW VERY BRIEFLY ON FRI. BOTH THE NAM AND GFS SHOW VERY
LITTLE UPPER LEVEL FORCING WITH THIS SYSTEM WITH BEST ENERGY
COMING IN THROUGH THE MID LEVELS AS SHORTWAVE CROSSES THE AREA
THROUGH FRI AFTN INTO THE EVENING. DURING THIS TIME SHOULD SEE
INCREASED CLDS IN E-NE FLOW AT LOW LEVELS AND PASSING UPPER LEVEL
CLOUDS. THE MOISTURE PROFILES SHOW AN INCREASE IN RH UP GREATER
THAN 90 PERCENT ABOVE H5 BUT VERY DRY AIR REMAINING IN THE MID
LEVELS. THEREFORE EXPECT LIMITED...IF ANY CHC OF SHALLOW PASSING
SHWRS.
BY END OF PERIOD A DEEP NW FLOW WILL SET UP IN THE MID LEVELS AS H5
TROUGH PUSHES FARTHER EAST. THE MAIN EFFECT OF THE FRONT WILL BE
INCREASED CLOUDS FRI AND A REINFORCEMENT AND SHIFT TO MORE
NORTHERLY WINDS FRI INTO SAT WITH ONLY A SLIGHT CHC OF PCP FRI.
TEMPERATURES NEAR CLIMO THROUGH THE PERIOD...MID 80S AND MID 60S.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...SPLIT FLOW PATTERN DEVELOPS AT THE START OF
THE PERIOD AS A NORTHERN STREAM TROUGH DRIVES A COLD FRONT TOWARDS
THE EASTERN CAROLINAS. THIS FRONT DIVES INTO A RELATIVELY DRY AIR
MASS...AND MID/UPPER FORCING ASSOCIATED WITH IT IS QUITE WEAK.
THEREFORE...EXPECT VERY LITTLE IN THE WAY OF PRECIP WITH ITS
PASSAGE...AND INSTEAD WILL JUST SEE AN INCREASE IN CLOUD COVER. AS
WINDS TURN MORE E/NE BEHIND THE FRONT...THIS ADVECTS ATLANTIC
MOISTURE INTO THE COLUMN. INHERITED FORECAST SHOWS SCHC POP FOR THE
WKND...AND WILL LEAVE THIS UNCHANGED. HOWEVER...FORECAST PROFILES
SHOW MUCH DRIER AIR ABOVE 750MB OR SO THAN WAS PREDICTED YESTERDAY
SINCE THE ATLANTIC FETCH REMAINS CONFINED TO THE LOWER PART OF THE
COLUMN. IF THIS TREND CONTINUES...MAY HAVE TO REMOVE ALL MENTION OF
TSTMS...ESPECIALLY ON SATURDAY. TEMPS WILL BE RIGHT AROUND CLIMO
DURING THE WKND.
SOUTHERN STREAM VORT ALONG THE GULF COAST WILL THEN ROTATE NORTHEAST
ON LEE SIDE OF DEVELOPING LONGWAVE TROUGH ACROSS THE PLAINS. AT THE
SAME TIME...DEEP SE FLOW DEVELOPS AND IT APPEARS THAT LATE MON/TUE
WILL BE THE BEST CHANCE FOR RAINFALL DURING THE EXTENDED. A SURFACE
REFLECTION TO THIS MID-LEVEL IMPULSE MAY WORK JUST WEST OF THE
CWA...WHICH ALLOWS FOR THE WARM FRONT AND ITS ASSOCIATED LIFT TO
CROSS US LATE MONDAY. STILL DIFFERENCES IN STRENGTH OF THIS FEATURE
FROM THE MODELS...SO WILL KEEP LOW-CHC POP FOR NOW. WILL NOTE THAT
IF THE ECMWF IS CORRECT THIS COULD END UP BEING A ROBUST RAINFALL
EVENT...BUT WITH GUIDANCE FLIPPING IN ITS AMPLIFICATION OF CENTRAL
5H TROUGH...WILL KEEP ONLY LIMITED QPF FOR NOW. BY WEDNESDAY THIS
FEATURE WILL BE WELL NE OF THE AREA AND DRYING WILL OCCUR.
TEMPS FOR THE FIRST HALF OF NEXT WEEK WILL BE AROUND CLIMO FOR
HIGHS...BUT LOWS WILL BE A FEW DEGREES ABOVE EACH NIGHT DUE TO
INCREASED SOUTHERLY FLOW AND CLOUD COVER.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...EXPECT VFR THROUGH THE VALID PERIOD...WITH EXCEPTION OF
POTENTIAL FOR SHORT-LIVED MVFR DUE TO FOG AT KLBT BEFORE SUNRISE.
LIGHT NORTHEAST WINDS WILL CONTINUE OVERNIGHT WITH A FEW LINGERING
LOW TO HIGH LEVEL CLOUDS ACROSS THE AREA. GIVEN GUIDANCE AND FCST
SOUNDINGS...CANNOT RULE OUT FOG AT KLBT BEFORE DAYBREAK...THOUGH
CONFIDENCE IS LOW. ATTM...HAVE OPTED TO KEEP TEMPO IN CURRENT FCST.
AFTER SUNRISE...EAST-NORTHEAST WINDS WILL INCREASE TO AOB 10 KTS FOR
THE REMAINDER OF THE DAY. INCREASING MOISTURE...ESPECIALLY ALONG THE
COAST...WILL ALLOW FOR LOW CLOUDS TO DEVELOP EARLY ON IN THE DAY.
COVERAGE WILL BE FEW/SCT...THOUGH DO NOT ANTICIPATE ANY RESTRICTIONS
TO ARISE. INTO THE EVENING HOURS...CLOUD COVERAGE WILL DECREASE AND
WINDS WILL BECOME LIGHT.
THE EXTENDED OUTLOOK THROUGH MONDAY...POTENTIAL FOR BRIEF REDUCED
VSBYS IN BR AT FOG PRONE TERMINALS KLBT/KFLO IN THE PRE-DAWN HOURS
THROUGH SUNDAY. OTHERWISE EXPECT VFR...WITH A SLIGHT CHANCE OF
SHOWERS SUNDAY AND A BETTER CHANCE ON MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1040 PM WEDNESDAY...CENTER OF HIGH PRESSURE WILL MOVE
OFFSHORE FROM THE NE STATES...BUT CONTINUE TO RIDGE BACK ACROSS THE
LOCAL WATERS OVERNIGHT. THIS PRESSURE PATTERN WILL PRODUCE A NE TO
ENE WIND DIRECTION OVERNIGHT. THE SFC PG WILL SLIGHTLY TIGHTEN AS A
RESULT OF THE HIGHS CENTER MOVING FURTHER AWAY FROM THE ILM
WATERS...AND THUS PRODUCE 15 TO OCCASIONALLY 20 KT WIND SPEEDS. AS
FOR SEAS...2 TO 4 FT NORTH OF CAPE FEAR...3 TO 5 FT FROM CAPE FEAR
SOUTHWARD. SEAS WILL PRIMARILY BE A SUMMATION OF 2 TO 4 FT WIND
DRIVEN WAVES AT 4 TO 5 SECOND PERIODS...AND A 1 TO 2 FT RESIDUAL
EASTERLY SWELL AT 9-12 SECOND PERIODS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...HIGH PRESSURE RIDGING DOWN FROM THE
NORTHEAST WILL GET SQUEEZED OUT AS COLD FRONT APPROACHES FROM THE
NORTHWEST LATE FRIDAY INTO SATURDAY. OVERALL WILL MAINTAIN A
DECENT E-NE FLOW THROUGH THURS WITH A SLIGHT BACKING TO THE NORTH
AS FRONT DRAWS CLOSER LATE FRI. PINCHED GRADIENT INITIALLY WILL
KEEP WINDS AROUND 15 KTS BUT AS GRADIENT RELAXES AND BACKS THROUGH
FRI EXPECT NE WINDS 10 TO 15 KTS AND DROPPING UNDER 10 KT FRI
NIGHT. SEAS WILL SUBSIDE FROM 3 TO 4 FT DOWN TO 2 TO 3 FT BY LATE
FRI AS WINDS DIMINISH. MAY SEE A FEW 5 FOOTERS IN OUTER WATERS EARLY
THURS.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...COLD FRONT WILL BE PUSHING SOUTH/OFFSHORE
AT THE START OF THE PERIOD. A WEAK SURGE WILL EXIST BEHIND THIS
FRONT...AND NE WINDS OF AROUND 10 KTS ARE EXPECTED THROUGH MUCH OF
THE WKND BEFORE SLOWLY VEERING TO THE SOUTH ON MONDAY...STILL
AROUND 10 KTS. THE LONG DURATION NE WIND ACROSS A LONG FETCH DOWN
THE EAST COAST WILL CREATE A 3-4 FT/8SEC NE SWELL WHICH COMBINES
WITH A 1-2 FT NE WIND WAVE TO PRODUCE 2-4 FT SEAS...WITH SOME 5
FOOTERS POSSIBLE NEAR THE 20NM BOUNDARY. AS WINDS TURN TO THE SOUTH
MONDAY...SEAS WILL FALL...BECOMING 2-3 FT ACROSS THE WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...SGL/RJD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
255 AM CDT THU SEP 13 2012
.DISCUSSION.../ISSUED AT 255 AM CDT/
LINGERING RAIN BAND IS ABOUT OUT OF SOUTHEAST CORNER OF AREA AND MID
AND HIGH CLOUDS WILL CONTINUE TO STEADILY DECREASE. THE HIGH CLOUDS
HAVE OBVIOUSLY BECOME THIN ENOUGH TO ALLOW FOR ENOUGH COOLING FOR
THE PATCHY FOG WE HAVE BEEN GOING FOR AS IT IS ALREADY DEVELOPING IN
A FEW PLACES. PLAN ON KEEPING INTO THE EARLY MORNING AND MAY ADJUST
AREA AT THE LAST MINUTE. THIS ADJUSTMENT COULD INCLUDE MAKING THE
FOG MORE THAN PATCHY AND SOME DENSE FOG NOT OUT OF THE QUESTION...
BUT THE DENSE STUFF SHOULD BE ISOLATED. COMING OUT OF THE FOG...WE
WILL GO INTO A CLEAR PERIOD WITH A SLOW WARMING TREND WHICH SHOULD
LAST THROUGH MOST OF THE COMING WEEKEND. LIGHT WINDS AT FIRST WILL
GIVE WAY TO A DEVELOPING SOUTHERLY FLOW. THE COMBINATION OF
WARMING...DRYING...AND INCREASING WINDS WILL LIKELY PRODUCE A
RETURN TO ELEVATED FIRE DANGER OVER THE WEEKEND AND WILL MENTION IN
HAZARDOUS WX OUTLOOK. GUIDANCE TEMPERATURES NEXT FEW DAYS LOOK
GENERALLY REASONABLE WITH A LIKELIHOOD OF A LITTLE GREATER DIURNAL
RANGE THAN WHAT GUIDANCE IS SHOWING IN THIS PATTERN.
LATE SUNDAY AND SUNDAY NIGHT COLD FRONT WILL COOL THE WX DOWN FOR
NEXT WEEK...THOUGH GUIDANCE WARMS IT UP SLIGHTLY AFTER INITIAL COOL
DOWN. GUIDANCE TEMPERATURES AGAIN LOOK RATHER MODERATE AND WILL GO
WITH THEM AS MODELS DIFFER ON THE STRENGTH OF COOL AIR INTRUSION.
THE GFS WOULD SUGGEST A DECENT FROST POTENTIAL LATE MONDAY NIGHT AND
EARLY TUESDAY MORNING.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE TAF PERIOD. WHERE
LINGERING LOW LEVEL MOISTURE REMAINS AND SKIES CLEAR...COULD SEE
PATCHY RADIATION FOG DEVELOP. HURON RECEIVED LIMITED AMOUNTS OF
RAIN...SO ANY FOG THERE SHOULD BE QUITE LIMITED. FURTHER TO THE
SOUTH AND EAST...CONTINUED MENTION OF FOG IN KFSD TERMINAL...BUT
LEFT MENTION OUT OF KSUX AS CONFIDENCE IS LOW THAT SKIES WILL CLEAR
ENOUGH TO RESULT IN FOG. HRRR DEVELOPS PATCHY DENSE FOG AROUND SIOUX
FALLS. WITH SCATTERED CLOUD COVER...CONFIDENCE IS IFFY WITH
FOG...BUT THE EARLIER THE CLEARING OCCURS...THE BETTER POTENTIAL
THERE IS FOR LOCALLY DENSE FOG.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1151 PM CDT WED SEP 12 2012
.DISCUSSION...
VFR CONDITIONS AND THUNDERSTORMS WILL DOMINATE WEST CENTRAL TEXAS
FOR THE NEXT 24 HOURS. SEE THE BELOW AVIATION SECTION FOR
ADDITIONAL INFORMATION.
&&
.AVIATION...
PLAN FOR THUNDERSTORMS TO DOMINATE WEST CENTRAL TEXAS WEATHER FOR
THE NEXT 24 HOURS. THE LATEST RUC BRINGS A SURFACE OUTFLOW
BOUNDARY ACROSS THE BIG COUNTRY AND INTO THE CONCHO VALLEY BY
AROUND 09Z. ALTHOUGH SHOWERS AND A FEW THUNDERSTORMS MAY ACCOMPANY
THIS BOUNDARY...I WILL LIKELY NOT INCLUDE ANY PREVAILING OR TEMPO
THUNDERSTORMS IN THE ABILENE OR SAN ANGELO TERMINALS FOR THAT TIME
FRAME. I WILL LIKELY INCLUDE A TEMPO WIND GROUP FOR THE ABILENE
TERMINAL FOR NORTHWEST WINDS FROM 08Z TO 12Z. OTHERWISE...THE
PREVIOUS TERMINALS LOOK ON TRACK.
HUBER
&&
.PREV DISCUSSION... /ISSUED 643 PM CDT WED SEP 12 2012/
DISCUSSION...
LOOK FOR VFR CONDITIONS AND THUNDERSTORMS TO DOMINATE WEST CENTRAL
TEXAS FOR THE NEXT 24 HOURS. AVIATION BELOW HAS DETAILS.
AVIATION...
MODELS CONTINUE TO INDICATE VFR CONDITIONS ACROSS WEST CENTRAL
TEXAS FOR THE NEXT 24 HOURS. IN ADDITION...AN APPROACHING UPPER-
LEVEL TROUGH OF LOW PRESSURE AND AN ASSOCIATED SURFACE COLD FRONT
WILL CONTINUE TO INITIATE SHOWERS AND THUNDERSTORMS ACROSS MANY
LOCATIONS IN WEST CENTRAL TEXAS DURING THE NEXT 24 HOURS. EXPECT
MAINLY SCATTERED SHOWERS AND A FEW THUNDERSTORMS OVERNIGHT
TONIGHT. THEN...PLAN FOR MANY MORE SHOWERS AND THUNDERSTORMS
TOMORROW...ESPECIALLY DURING THE AFTERNOON HOURS.
HUBER
PREV DISCUSSION... /ISSUED 408 PM CDT WED SEP 12 2012/
SHORT TERM...
CHANGES ARE ON THE HORIZON FOR WEST CENTRAL TEXAS AS WE DEVIATE FROM
OUR FAMILIAR HOT AND DRY TO MUCH COOLER AND WET WX CONDITIONS FOR
THE NEXT FEW DAYS. WE ALREADY HAVE A FAIRLY EXPANSIVE MID LEVEL
CLOUD DECK OVER WEST TX WITH SOME ASSOCIATED LIGHT RADAR ECHOS OVER
THE SOUTH PLAINS. MOST OF THIS HAS NOT BEEN REACHING THE GROUND BUT
INTENSITIES HAVE BEEN INCREASING OVER THE PAST HOUR OR SO AS THE
LEADING EDGE OF ENHANCED SYNOPTIC SCALE ASCENT OVERSPREADS THE AREA.
THIS IS ASSOCIATED WITH A COMPACT SHORTWAVE TROF CURRENTLY LOCATED
JUST TO THE ESE OF EL PASO IN CONJUNCTION WITH THE LARGER TROF
MOVING ACROSS THE ROCKIES. AS THIS FEATURE APPROACHES...LIFT WILL
INCREASE ACROSS THE REGION AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP...MAINLY TOWARD MIDNIGHT AND THEREAFTER.
LOOKING UPSTREAM...A COLD FRONT HAS MOVED INTO THE PANHANDLE AND
WILL MOVE SOUTH OVERNIGHT...REACHING THE I-20 CORRIDOR BY AROUND
12Z. AS THIS COLD FRONT PROGRESSES SOUTH DURING THE DAY...COLD
ADVECTION AND ABUNDANT CLOUD COVER WILL AID IN KEEPING TEMPS
GENERALLY IN THE 70S. LOWER TO MID 80S ARE EXPECTED OVER THE
SOUTHEAST ZONES WHERE A LATER FROPA WILL ALLOW TEMPS TO WARM THROUGH
EARLY AFTERNOON. POPS WERE RAISED ACROSS THE BOARD WITH 70-90
PERCENT CHANCES IN MOST AREAS. LOCALIZED RAINFALL AMOUNTS MAY EXCEED
1-2 INCHES IN AREAS WHERE THE STRONGER CELLS DEVELOP. MOST AREAS ARE
EXPECTED TO SEE IN EXCESS OF 1/2 INCH.
JOHNSON
LONG TERM...
A WEAK CLOSED LOW IS PROGGED TO DEVELOP NEAR THE TEXAS/NEW MEXICO
BORDER THURSDAY NIGHT...WITH THE TROUGH AXIS EXTENDING TO THE
SOUTHWEST INTO SOUTHERN ARIZONA. LITTLE MOVEMENT WITH THIS UPPER
LOW AND TROUGH ARE INDICATED FOR FRIDAY. THE MODELS HAVE TRENDED
SLOWER WITH THE PROGRESSION OF THIS SYSTEM...WITH THE TROUGH AXIS
NOT EXPECTED TO MOVE EAST ACROSS WEST CENTRAL TEXAS UNTIL LATE
SATURDAY NIGHT/EARLY SUNDAY MORNING. A COOL AND MOIST AIRMASS IS
FORECAST TO REMAIN OVER OUR AREA THROUGH FRIDAY AND INTO SATURDAY.
PRECIPITABLE WATER VALUES NEAR OR ABOVE 1.5 INCHES WILL BE PRESENT
FRIDAY. WITH THIS MOISTURE AND LIFT ASSOCIATED WITH THE UPPER
TROUGH TO OUR WEST/NORTHWEST...EXPECT NUMEROUS SHOWERS AND A FEW
THUNDERSTORMS TO OCCUR THURSDAY NIGHT AND FRIDAY. RAIN CHANCES
WILL BEGIN TO DECREASE FRIDAY NIGHT...AND HAVE LOW CHANCE POPS
TRAILING OFF FROM THE NORTHWEST SATURDAY AND SATURDAY NIGHT.
WITH THE COMBINATION OF OVERCAST CONDITIONS...PRECIPITATION AND A
COOL AIRMASS IN PLACE...TEMPERATURES ON FRIDAY WILL BE WELL-BELOW
NORMAL. NOT EXPECTING MUCH BEYOND A 10 DEGREE TEMPERATURE RECOVERY
DURING THE DAY FRIDAY. HAVE REDUCED THE DIURNAL TEMPERATURE RANGE
THROUGH SATURDAY...GIVEN THE MOIST CONDITIONS AND PERSISTENT CLOUD
COVER.
DECREASING CLOUD COVER FROM THE NORTHWEST IS EXPECTED ON SUNDAY...
AS THE TROUGH MOVES EAST OF OUR AREA AND DRIER AIR ADVECTS INTO
WEST CENTRAL TEXAS. THE AIRMASS WILL MODIFY QUICKLY WITH TEMPERATURES
REACHING THE MID TO UPPER 80S FOR HIGHS SUNDAY. A WARMING TREND IS
INDICATED EARLY NEXT WEEK PER THE 850 MB THERMAL PATTERN.
THE 12Z MODELS CAST MORE DOUBT ON SOUTHWARD PROGRESS OF A COLD FRONT
INTO OUR AREA AND ASSOCIATED RAIN CHANCES NEXT TUESDAY. INDICATIONS
ARE FOR THIS TO BE A WEAK FRONT AT BEST. HAVE RETAINED THE SLIGHT
CHANCE POP FOR NOW AND HAVE TRENDED DAILY MAXIMUM TEMPERATURES
WARMER NEXT WEEK.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 67 76 60 70 59 / 30 80 50 50 30
SAN ANGELO 70 79 60 70 60 / 30 80 60 60 40
JUNCTION 70 84 63 73 61 / 20 70 60 60 50
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
HUBER
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
307 AM CDT THU SEP 13 2012
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
307 AM CDT THU SEP 13 2012
MAIN FORECAST CONCERNS ARE ON TIMING THE END OF ONGOING
PRECIPITATION...POTENTIAL FOR FROST AND VALLEY FOG TONIGHT...AND
POSSIBLE FIRE WEATHER CONCERNS FOR SATURDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO SOUTHWEST CANADA...
TROUGHING FROM SOUTH CENTRAL CANADA INTO NEBRASKA...AND RIDGING
ALONG THE EAST COAST. WITHIN THE UPPER TROUGHING...NOTABLE FEATURES
INCLUDE A SHORTWAVE OVER NORTHWEST IOWA AND AN UPPER LOW OVER
CENTRAL SASKATCHEWAN. THE FORECAST AREA RESIDES IN SOUTHWEST FLOW
AHEAD OF THE NORTHWEST IOWA SHORTWAVE...AS WELL AS IN A RIGHT
ENTRANCE REGION OF A 100-120KT JET AT THE TROPOPAUSE EXTENDING
FROM CENTRAL MINNESOTA INTO NORTHERN ONTARIO. THE FORECAST AREA
ALSO RESIDES IN A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH
SHOWS UP IN 700MB PROFILER DATA AS WELL AS IN 850MB TEMPS FROM 00Z
RAOBS (8C AT MPX COMPARED TO 13C AT GRB AND 16C AT DVN). THE
COMBINATION OF ALL THESE FORCING FEATURES RESULTING IN A BAND OF
SHOWERS FROM THE OKLAHOMA AND TEXAS PANHANDLES NORTHEASTWARD TO LA
CROSSE AND INTO EASTERN UPPER MICHIGAN. BACK EDGE OF SHOWERS WAS
NEAR ALBERT LEA AND DODGE CENTER MN. BACK EDGE OF THE CIRRUS CLOUD
COVER WAS QUITE A BIT FARTHER NORTHWEST...THOUGH...NEAR ST CLOUD.
PLENTY OF LOW LEVEL DRY AIR ALSO TO THE NORTHWEST...NOTED BY
SURFACE DEWPOINTS IN THE TEENS AND LOW 20S ACROSS NORTH DAKOTA TO
ALEXANDRIA MN. GOES SOUNDER PRECIPITABLE WATER IMAGERY DEPICTING
VALUES AROUND 0.3 INCHES OVER NORTH DAKOTA...OR ABOUT 50 PERCENT
OF NORMAL.
TODAY AND TONIGHT...AFTER MUCH STRUGGLES THE PAST COUPLE DAYS WITH
THE UPPER LOW IN SASKATCHEWAN...MODELS ARE ALL NOW IN SYNC WITH
BASICALLY WHAT THE OUTLIER 11.00Z NAM SUGGESTED. MODELS DROP THE
UPPER LOW INTO THE MEAN TROUGHING... REACHING NORTHERN MINNESOTA
BY 00Z. THE UPPER LOW THEN RAPIDLY HEADS EAST TO NORTHERN LOWER
MICHIGAN BY 12Z FRIDAY. MEANWHILE...THE NORTHWEST IOWA SHORTWAVE
IS PROGGED TO MOVE NORTHEAST THROUGH THE FORECAST AREA DURING THE
DAY TODAY. THE COMBINATION OF THE UPPER LOW AND IOWA SHORTWAVE WILL
PUSH THE FRONTOGENESIS ZONE AND ITS ASSOCIATED SHOWERS EAST OUT OF
THE FORECAST AREA. TIMING WISE...MOST OF THE AREA SHOULD BE DRY
AFTER 18Z. IN ADDITION...AS THE UPPER LOW APPROACHES...DRIER AIR
AND CLEARING SEEN OFF TO OUR NORTHWEST OVER THE DAKOTAS AND
NORTHWEST MINNESOTA WILL ADVECT IN. PREVIOUSLY THERE WAS CONCERN
ABOUT THE UPPER LOW DROPPING INTO MINNESOTA BRINGING SOME ISOLATED
PRECIPITATION TO THE AREA. HOWEVER...NOW THAT MODELS ARE TRACKING
THE UPPER LOW SO FAR NORTH...AND ITS TIMING DOES NOT COINCIDE WITH
PEAK HEATING...NOT ANTICIPATING ANY PRECIPITATION WITH IT.
THEREFORE...DRY CONDITIONS ARE EXPECTED ONCE THE PRECIPITATION
ASSOCIATED WITH THE FRONTOGENESIS ENDS. IN FACT...INDICATIONS ARE
THAT MUCH OF THE FORECAST AREA WILL BE CLEAR TONIGHT. WITH
PRECIPITABLE WATER VALUES DROPPING TO 0.3-0.4 INCHES AND LIGHT
WINDS ASSOCIATED WITH HIGH PRESSURE OVERHEAD AFTER MIDNIGHT...
TEMPERATURES ARE GOING TO TANK. HAVE LEANED TOWARDS THE COLDER OF
GUIDANCE...DROPPING THE TYPICAL COLD SPOTS IN WISCONSIN TO NEAR
FREEZING WITH MID 30S TO MID 40S ELSEWHERE. PATCHY FROST LOOKS
LIKELY ACROSS TAYLOR...CLARK... JACKSON...MONROE...JUNEAU AND
ADAMS COUNTIES. APPEARS FROST COVERAGE RIGHT NOW SHOULD STAY LOW
ENOUGH TO PRECLUDE THE NEED FOR ANY ADVISORY. WITH RECENT RAINS
AND LATE IN THE DAY CLEARING...VALLEY FOG ALSO LOOKS LIKELY FOR
THE WISCONSIN RIVER VALLEY AND MISSISSIPPI RIVER TRIBUTARIES. THE
MAIN MISSISSIPPI VALLEY HAS A CONCERN WITH THE DRY AIR
IMPACT...GIVEN THAT TEMP/DEWPOINT SPREADS OF AT LEAST 30F ARE
POSSIBLE BY LATE THIS AFTERNOON. LIGHT WINDS EXTENDING UP A FEW
THOUSAND FEET AND RECENT RAIN SHOULD ALLOW GOOD DEWPOINT RECOVERY
THIS EVENING...BUT WHETHER IT IS ENOUGH IS UNCERTAIN. THEREFORE...
HAVE KEPT THE MISSISSIPPI RIVER VALLEY AT PATCHY FOG FOR THE
PRESENT TIME.
FRIDAY THROUGH SATURDAY NIGHT...MODELS SHOW THAT THE RIDGING
CURRENTLY OVER SOUTHWEST CANADA WILL BREAK DOWN...IN RESPONSE TO
TROUGHING OVER THE GULF OF ALASKA PUSHING EAST. AS SUCH...WE SHOULD
SEE THE FLOW OVER THE NORTHERN U.S. TURN MORE ZONAL....ALLOWING SOME
WARMER AIR THAT GETS DOWNSLOPED OFF THE ROCKIES TO PUSH INTO THE
FORECAST AREA. THERE ARE INDICATIONS THAT TOWARDS LATE SATURDAY
NIGHT SOME WEAK RIDGING WILL BUILD OVER THE WESTERN GREAT LAKES...IN
RESPONSE TO THE GULF OF ALASKA TROUGHING STALLING OVER CENTRAL
CANADA. EXPECT A COLD FRONT TO SEPARATE THE TROUGHING/RIDGING
INTERFACE...WHICH BY 12Z SUNDAY WILL EXTEND FROM NORTHWEST ONTARIO
SOUTHWEST INTO CENTRAL SOUTH DAKOTA. PLENTY OF DRY AIR FROM THE
LOW TO UPPER LEVELS OF THE TROPOSPHERE AHEAD OF THE FRONT IS
EXPECTED TO PRODUCE CLEAR SKIES FOR MUCH OF THIS PERIOD. A
TIGHTENING PRESSURE GRADIENT AHEAD OF THE FRONT SHOULD HELP TO
INCREASE THE WINDS OVER THE FORECAST AREA...BEGINNING FRIDAY NIGHT
AND ESPECIALLY FOR SATURDAY AND SATURDAY NIGHT. WITH MORE
WIND...AS WELL AS PRECIPITABLE WATER VALUES PROGGED TO CLIMB TO
AROUND 0.5 INCHES... ANTICIPATE WARMER LOWS FOR FRIDAY NIGHT AND
THUS LITTLE CONCERN FOR FOG OR FROST. 850MB TEMPS OF 8-10C ON
FRIDAY SHOULD ALLOW FOR HIGHS IN THE LOWER 70S. ON SATURDAY...
THOSE 850MB TEMPS CLIMB TO 11-13C AND WITH THE INCREASING
SOUTHWEST WIND...TEMPERATURES SHOULD TOP OUT IN THE MID TO UPPER
70S. A FEW LOCATIONS MAY EVEN REACH 80. MAY HAVE TO WATCH FIRE
WEATHER CONDITIONS FOR SATURDAY. SEE FIRE WEATHER DISCUSSION
BELOW. EVEN WARMER LOWS EXPECTED SATURDAY NIGHT WITH A SOUTHWEST
BREEZE CONTINUING...THOUGH THE DRY AIR LIKELY ALLOWING SOME OF THE
TYPICAL COLD SPOTS TO DROP INTO THE LOW TO MID 40S.
.LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT
307 AM CDT THU SEP 13 2012
13.00Z ECMWF/GFS/UKMET AND GFS ENSEMBLES ARE IN EXCELLENT AGREEMENT
ON A MAJOR PATTERN SHIFT FOR THE LONG TERM PERIOD. THE 13.00Z
CANADIAN HAS THE PATTERN SHIFT TOO...BUT WILL BE DISCOUNTED AS AN
OUTLIER SINCE THE POSITION OF THE UPPER TROUGHING COME 00Z TUESDAY
AND ESPECIALLY BY 00Z WEDNESDAY DOES NOT AGREE WITH THE
AFOREMENTIONED MODELS.
ON SUNDAY...RIDGING REALLY AMPLIFIES OVER FAR WESTERN CANADA. IN
TURN...THIS FORCES A DEEPENING TROUGH DOWNSTREAM...WHICH DIGS DOWN
INTO THE NORTHERN PLAINS SUNDAY NIGHT. THIS TROUGH DIGGING DOWN
SHOULD HELP PUSH EASTWARD THE COLD FRONT THAT WAS OVER SOUTH DAKOTA
12Z SUNDAY. IT APPEARS THE FRONT WILL CROSS THE FORECAST AREA SUNDAY
NIGHT. PRIOR TO THE FRONTAL PASSAGE...SUNDAY SHOULD BE ANOTHER WARM
DAY WITH 850MB TEMPS OF 12-14C AND PLENTY OF SUN. HIGHS ARE LIKELY
TO BE EQUAL TO OR SLIGHTLY HIGHER THAN SATURDAY. ANOTHER
FRONTOGENETIC BAND OF PRECIPITATION LOOKS TO DEVELOP ON THE COOL
SIDE OF THE FRONT. THEREFORE...40-60 PERCENT CHANCES OF PRECIPITATION
EXIST ACROSS THE FORECAST AREA FOR BOTH SUNDAY NIGHT AND MONDAY.
FUTURE SHIFTS MAY BE ABLE TO INCREASE THESE MORE. ADDED A LOW
CHANCE OF THUNDER AS WELL GIVEN MUCAPE FORECASTS OF 300 J/KG OR SO
WITH THE FRONTOGENESIS BAND. THE UPPER TROUGH LOOKS TO DIG INTO
THE AREA FOR MONDAY NIGHT AND TUESDAY. COMBINATION OF COOL
TEMPERATURES ALOFT AND ANY SHORTWAVES MOVING THROUGH THE TROUGH
RESULTS IN THE NEED TO MAINTAIN 20-30 PERCENT CHANCES DURING THIS
TIME FRAME. A BRIEF BREAK IN PRECIPITATION IS ANTICIPATED TUESDAY
NIGHT...THEN MODELS HAVE ANOTHER POTENT SHORTWAVE DROPPING DOWN
INTO THE NORTHERN PLAINS ON WEDNESDAY. SOME WARM ADVECTION AND
DPVA FORCED PRECIPITATION IS POSSIBLE AHEAD OF IT...THOUGH
AVAILABLE MOISTURE IS A QUESTION MARK...THUS CONSENSUS 20 PERCENT
CHANCES ARE WARRANTED.
AS THE UPPER TROUGH DROPS INTO THE AREA ON MONDAY...850MB TEMPS
REALLY TUMBLE. BY 00Z TUESDAY...THEY ARE FORECAST DOWN TO AT LEAST
3-6C AND MAY EVEN FALL A LITTLE MORE...ESPECIALLY AS WE HEAD TO 12Z
TUESDAY. AS A RESULT...BOTH MONDAY AND TUESDAY LOOK CHILLY WITH
HIGHS IN THE 60S MONDAY AND 50S TUESDAY. 850MB TEMPS SHOULD WARM
BACK UP TUESDAY NIGHT INTO WEDNESDAY...PERHAPS PEAKING AS HIGH AS
8-11C PER 13.00Z ECMWF...IN RESPONSE TO THE NEXT POTENT SHORTWAVE
DROPPING THROUGH THE TROUGH. THEREFORE...HIGHS SHOULD CLIMB BACK
INTO THE 60S FOR WEDNESDAY.
FOR THOSE LOOKING FARTHER OUT...IT APPEARS THE MEAN UPPER TROUGHING
WILL STAY IN PLACE AND PERHAPS EVEN AMPLIFY THROUGH THE END OF NEXT
WEEK...PER THE 13.00Z ECMWF/GFS. THIS IS ALSO IN GOOD AGREEMENT WITH
THE 12.00Z CFS WHICH HAS BEEN SHOWING A CONSISTENT SIGNAL OF
BELOW NORMAL TEMPERATURES FOR THE LATTER HALF OF SEPTEMBER OVER
THE CENTRAL AND EASTERN PORTION OF THE U.S.
&&
.AVIATION...THROUGH 06Z FRIDAY
1146 PM CDT WED SEP 12 2012
BAND OF POST FRONT RAINS CONTINUES ACROSS THE AREA WITH VFR
CONDITIONS. EXPECT THIS RAIN TO REMAIN OVER THE AREA FOR MUCH OF
THE NIGHT AS A WEAK SHORT WAVE TROUGH COMING OUT OF NEBRASKA HOLDS
THE FRONT AND THE FRONTOGENESIS IN PLACE. ONCE THIS WAVE CLEARS
THE AREA EARLY THURSDAY MORNING...EXPECT THE RAIN WILL END AROUND
12Z. LITTLE CHANGE IN CONDITIONS EXPECTED TO OCCUR WHILE IT IS
RAINING WITH JUST AN OUTSIDE CHANCE AT SOME MVFR CONDITIONS. SKIES
SHOULD CLEAR OUT THURSDAY AFTERNOON AS HIGH PRESSURE BUILDS INTO
THE AREA. THE 13.00Z NAM CONTINUES THE TREND OF SHOWING DEEP MIXING
OCCURRING THURSDAY AFTERNOON WITH THE HIGH. WINDS STILL LOOK TO BE
FAIRLY UNIFORM IN THE MIXED LAYER WITH SUSTAINED SPEEDS AROUND 10
TO 12 KNOTS. COULD BE SOME SLIGHTLY HIGHER GUSTS AND HAVE INCLUDED
THIS POSSIBILITY FOR KRST. THE WINDS SHOULD RAPIDLY DIMINISH NEAR
SUNSET AND WITH THE CLEAR SKIES...COULD BE A VALLEY FOG NIGHT
SETTING UP FOR KLSE. WILL HAVE TO SEE HOW MUCH MIXING OCCURS
THURSDAY AFTERNOON AND HOW BIG THE TEMP/DEW POINT SPREADS BECOME
BEFORE COMMITTING TO SOME FOG.
&&
.FIRE WEATHER...FRIDAY AND SATURDAY
307 AM CDT THU SEP 13 2012
ON FRIDAY...HIGH PRESSURE OVERHEAD COMBINED WITH PLENTY OF DRY AIR
WILL RESULT IN RELATIVE HUMIDITY VALUES DROPPING TO AROUND 25
PERCENT ACROSS MUCH OF THE AREA. RECENT RAINS PLUS WINDS LESS THAN
10 MPH SHOULD PRECLUDE ANY FIRE WEATHER CONCERNS...THOUGH THE DRY
AIR AND FULL SUNSHINE WILL HELP TO DRY OUT FUELS.
ON SATURDAY...THE COMBINATION OF SOUTHWEST WINDS INCREASE TO 10 TO
15 MPH WITH HIGHER GUSTS...ALONG WITH PLENTY OF DRY AIR IN THE
ATMOSPHERE ALLOWING FOR GOOD MIXING SHOULD SEND RELATIVE HUMIDITY
VALUES PLUMMETING TO 25 TO 30 PERCENT IN THE AFTERNOON. LOWEST
RELATIVE HUMIDITY VALUES AND HIGHEST WINDS LOOK TO OCCUR WEST OF THE
MISSISSIPPI RIVER. IN ADDITION...HIGH TEMPERATURES ARE EXPECTED TO
TOP OUT IN THE MID TO UPPER 70S. WILL HAVE TO WAIT AND SEE HOW MUCH
THE FUELS DRY OUT OVER THE NEXT TWO DAYS...BUT AT LEAST WEATHER WISE
THERE IS SOME CONCERN FOR INCREASED WILDFIRE POTENTIAL. THE CONCERN
WOULD ONLY INCREASE WITH A LITTLE MORE WIND AND/OR LOWER RELATIVE
HUMIDITY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
307 AM CDT THU SEP 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...04
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1200 PM EDT THU SEP 13 2012
.SYNOPSIS...
ISSUED AT 340 AM EDT THU SEP 13 2012
CLOUDS WILL INCREASE THIS MORNING AND SHOWERS WILL GRADUALLY
BECOME MORE COMMONPLACE INTO THE AFTERNOON AND EVENING. THE RAIN
IS EXPECTED TO END FROM NORTHWEST TO SOUTHEAST LATER TONIGHT. HIGH
PRESSURE WILL RETURN FOR THE WEEKEND BRINGING SUNSHINE AND
TEMPERATURES IN THE UPPER 60S TO MID 70S.
&&
.UPDATE...
ISSUED AT 1058 AM EDT THU SEP 13 2012
TOUCHED UP THE FORECAST FROM THIS AFTERNOON THROUGH TONIGHT IN
TERMS OF POPS AND WEATHER. FOLLOWED THE LEAD OF BOTH THE HRRR AND
THE NSSL 4KM WRF MODELS WHICH BRING A BAND OF RAIN THROUGH THE
FORECAST AREA LATE THIS AFTERNOON THROUGH TONIGHT. MAIN CHANGE WAS
TO BACK OFF ON THE ARRIVAL TIME A BIT. THROUGH THIS
AFTERNOON AND EARLY EVENING...THE FAR NORTHWEST CWA NORTH OF MUSKEGON
AND BIG RAPIDS SHOULD BE THE MAIN AREA THAT IS AFFECTED BY RAIN.
IT WILL TAKE MORE INTO THE EVENING AND AFTER DARK TO AFFECT AREAS
LIKE GRAND RAPIDS. TEMPERATURES WILL BE HELD DOWN BY THE CLOUDS
MOVING INTO THE FAR NORTHWEST FORECAST AREA. TOWARD JXN HOWEVER
READINGS WILL LIKELY PUSH AT LEAST TO AROUND 80...IF NOT ECLIPSING
IT SLIGHTLY.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 340 AM EDT THU SEP 13 2012
A BAND OF RAIN WAS MOVING ACROSS WISCONSIN THIS MORNING AND SHOULD
REACH THE NW CORNER OF THE CWA NEAR LDM BY EARLY TO MID MORNING.
THE SOUTHEASTWARD MOVEMENT OF THE PCPN WILL BE SLOW...PROBABLY NOT
REACHING GRR UNTIL MID TO LATE AFTERNOON...AND ONLY REACHING THE
JXN AREA INTO THE EVENING.
THE UPPER FORCING AND FGEN PRODUCING THIS PCPN LOOKS WEAKER THAN
WHAT WAS SEEN ON PREVIOUS MODEL RUNS. I AM STILL HIGHLY CONFIDENT
IN MEASURABLE RAIN...HOWEVER IT NO LONGER LOOKS LIKE A GOOD
SOAKING RAIN. MOST AREAS WILL PROBABLY END UP WITH A QUARTER TO A
HALF INCH OF RAIN.
AS HAS BEEN THE TREND WITH THE MODELS...THIS SYSTEM MOVES OUT MUCH
QUICKER...AND MUCH OF THE PCPN SHOULD BE EAST BY 12Z FRIDAY. HAVE
REMOVE THE LOW CHANCE POPS FOR FRIDAY.
A VERY DRY AIR MASS FOLLOWS FOR FRIDAY NIGHT AND SATURDAY. THIS
WILL PRODUCE A LARGE DIURNAL TEMP SWING. ADJUSTED TEMPS DOWN FRIDAY
NIGHT WITH 40S COMMON. THEN INCREASED MAX TEMPS ON SATURDAY...WARMING
TO 70 TO 75.
MEANWHILE...IT LOOKS LIKE MUCH OF THE CWA WILL SEE SOME EARLY
MORNING SUNSHINE TODAY. SO HAVE ALSO INCREASED MAX TEMPS FOR TODAY
WITH THE EXCEPTION BEING IN THE NW CWA WHERE THE RAIN WILL ARRIVE
EARLY...HOLDING TEMPS IN THE 60S THERE.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 AM EDT THU SEP 13 2012
AS THE SFC RIDGE MOVES SLOWLY OFF TO THE EAST SATURDAY NIGHT AND
SUNDAY... A WARM ADVECTION PATTERN DEVELOPS AND TEMPERATURES WILL
MODERATE. THE ATMOSPHERE REMAINS QUITE DRY HOWEVER AND WOULD EXPECT
SKIES TO REMAIN MOSTLY CLEAR UNTIL MONDAY AFTERNOON WHEN THE NEXT
COLD FRONT APPROACHES FROM THE WEST. THAT FRONT WILL BRING OUR NEXT
CHANCE OF RAIN SHOWERS LATE MONDAY AND MONDAY NIGHT.
A DEEP H5 TROUGH IS PROGGED TO DIG INTO THE REGION ON TUESDAY WITH
SOME RATHER CHILLY AIR RUSHING IN BEHIND THE COLD FRONT MONDAY
NIGHT. H8 TEMPS DROPPING DOWN TO 1-3C WILL BE PLENTY COLD TO
GENERATE SOME ADDITIONAL LAKE EFFECT CLOUDS AND RAIN SHOWERS BEHIND
THE FRONT ON TUESDAY. THE PATTERN LOOKS PROGRESSIVE HOWEVER... AND
THE TROUGH IS EXPECTED TO KICK OUT ON TUESDAY NIGHT... WITH WARM
ADVECTION RETURNING ALREADY ON WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1200 PM EDT THU SEP 13 2012
VFR CONDITIONS THIS AFTERNOON WILL GRADUALLY TRANSITION TO MVFR
TONIGHT AS LOW CLOUDS AND A BAND OF SHOWERS GRADUALLY MOVE IN FROM
THE WEST. SHOWERS SHOULD REACH KMKG BY LATE AFTN AND THE REST OF THE
TERMINALS THIS EVENING. CONDITIONS WILL GRADUALLY IMPROVE BACK TO
VFR FRIDAY MORNING AS THE LOWER CLOUDS AND SHOWERS EXIT THE AREA. NW
WINDS WILL RAMP UP TO 10-15 KTS BY LATE FRIDAY MORNING AS CLOUDS
SCATTER OUT BEFORE SKIES EVENTUALLY CLEAR.
&&
.MARINE...
ISSUED AT 934 AM EDT THU SEP 13 2012
WE HAVE EXPANDED THE SMALL CRAFT ADVISORY NORTH TO NOW INCLUDE THE
ENTIRE NEARSHORE. WE HAVE ALSO PULLED THE STARTING TIME OF THE
ADVISORY TO THE CURRENT TIME. THE BUOY OFF OF BIG SABLE POINT
INDICATES WAVES AROUND 5 FEET OR SO THIS MORNING IMMEDIATELY BEHIND
THE COLD FRONT MOVING THROUGH. WINDS AND WAVES ARE PICKING UP ALONG
THE ENTIRE COAST...A LITTLE QUICKER THAN EARLIER ANTICIPATED. WINDS
WILL PICK UP DOWN SOUTH TODAY...AND WINDS WILL DIMINISH LATER TODAY
AND THIS EVENING UP NORTH.
WE COULD BE FLIRTING WITH ADVISORY CRITERIA ONCE AGAIN ON FRIDAY
WITH WINDS EXPECTED TO BE APPROACHING 20 KNOTS. WITH THE COOLER AIR
OVER LAKE MICHIGAN...THAT COULD HELP BUILD WAVES ONCE AGAIN. WE WILL
LET THE CURRENT ADVISORY PLAY OUT FOR NOW. WE WILL RE-EVALUATE THE
NEED LATER TO EITHER EXTEND THE CURRENT ADVISORY...OR LET IT EXPIRE
AND ISSUE A NEW ONE IF NEEDED.
&&
.HYDROLOGY...
ISSUED AT 340 AM EDT THU SEP 13 2012
MOST AREAS WILL SEE LESS THAN A HALF INCH OF RAIN LATER TODAY
THROUGH TONIGHT. THIS WILL NOT CAUSE ANY HYDRO ISSUES.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LMZ844>846.
&&
$$
UPDATE...DUKE
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...MEADE
AVIATION...LAURENS
HYDROLOGY...JK
MARINE...NJJ
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1059 AM EDT THU SEP 13 2012
.SYNOPSIS...
ISSUED AT 340 AM EDT THU SEP 13 2012
CLOUDS WILL INCREASE THIS MORNING AND SHOWERS WILL GRADUALLY
BECOME MORE COMMONPLACE INTO THE AFTERNOON AND EVENING. THE RAIN
IS EXPECTED TO END FROM NORTHWEST TO SOUTHEAST LATER TONIGHT. HIGH
PRESSURE WILL RETURN FOR THE WEEKEND BRINGING SUNSHINE AND
TEMPERATURES IN THE UPPER 60S TO MID 70S.
&&
.UPDATE...
ISSUED AT 1058 AM EDT THU SEP 13 2012
TOUCHED UP THE FORECAST FROM THIS AFTERNOON THROUGH TONIGHT IN
TERMS OF POPS AND WEATHER. FOLLOWED THE LEAD OF BOTH THE HRRR AND
THE NSSL 4KM WRF MODELS WHICH BRING A BAND OF RAIN THROUGH THE
FORECAST AREA LATE THIS AFTERNOON THROUGH TONIGHT. MAIN CHANGE WAS
TO BACK OFF ON THE ARRIVAL TIME A BIT. THROUGH THIS
AFTERNOON AND EARLY EVENING...THE FAR NORTHWEST CWA NORTH OF MUSKEGON
AND BIG RAPIDS SHOULD BE THE MAIN AREA THAT IS AFFECTED BY RAIN.
IT WILL TAKE MORE INTO THE EVENING AND AFTER DARK TO AFFECT AREAS
LIKE GRAND RAPIDS. TEMPERATURES WILL BE HELD DOWN BY THE CLOUDS
MOVING INTO THE FAR NORTHWEST FORECAST AREA. TOWARD JXN HOWEVER
READINGS WILL LIKELY PUSH AT LEAST TO AROUND 80...IF NOT ECLIPSING
IT SLIGHTLY.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 340 AM EDT THU SEP 13 2012
A BAND OF RAIN WAS MOVING ACROSS WISCONSIN THIS MORNING AND SHOULD
REACH THE NW CORNER OF THE CWA NEAR LDM BY EARLY TO MID MORNING.
THE SOUTHEASTWARD MOVEMENT OF THE PCPN WILL BE SLOW...PROBABLY NOT
REACHING GRR UNTIL MID TO LATE AFTERNOON...AND ONLY REACHING THE
JXN AREA INTO THE EVENING.
THE UPPER FORCING AND FGEN PRODUCING THIS PCPN LOOKS WEAKER THAN
WHAT WAS SEEN ON PREVIOUS MODEL RUNS. I AM STILL HIGHLY CONFIDENT
IN MEASURABLE RAIN...HOWEVER IT NO LONGER LOOKS LIKE A GOOD
SOAKING RAIN. MOST AREAS WILL PROBABLY END UP WITH A QUARTER TO A
HALF INCH OF RAIN.
AS HAS BEEN THE TREND WITH THE MODELS...THIS SYSTEM MOVES OUT MUCH
QUICKER...AND MUCH OF THE PCPN SHOULD BE EAST BY 12Z FRIDAY. HAVE
REMOVE THE LOW CHANCE POPS FOR FRIDAY.
A VERY DRY AIR MASS FOLLOWS FOR FRIDAY NIGHT AND SATURDAY. THIS
WILL PRODUCE A LARGE DIURNAL TEMP SWING. ADJUSTED TEMPS DOWN FRIDAY
NIGHT WITH 40S COMMON. THEN INCREASED MAX TEMPS ON SATURDAY...WARMING
TO 70 TO 75.
MEANWHILE...IT LOOKS LIKE MUCH OF THE CWA WILL SEE SOME EARLY
MORNING SUNSHINE TODAY. SO HAVE ALSO INCREASED MAX TEMPS FOR TODAY
WITH THE EXCEPTION BEING IN THE NW CWA WHERE THE RAIN WILL ARRIVE
EARLY...HOLDING TEMPS IN THE 60S THERE.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 AM EDT THU SEP 13 2012
AS THE SFC RIDGE MOVES SLOWLY OFF TO THE EAST SATURDAY NIGHT AND
SUNDAY... A WARM ADVECTION PATTERN DEVELOPS AND TEMPERATURES WILL
MODERATE. THE ATMOSPHERE REMAINS QUITE DRY HOWEVER AND WOULD EXPECT
SKIES TO REMAIN MOSTLY CLEAR UNTIL MONDAY AFTERNOON WHEN THE NEXT
COLD FRONT APPROACHES FROM THE WEST. THAT FRONT WILL BRING OUR NEXT
CHANCE OF RAIN SHOWERS LATE MONDAY AND MONDAY NIGHT.
A DEEP H5 TROUGH IS PROGGED TO DIG INTO THE REGION ON TUESDAY WITH
SOME RATHER CHILLY AIR RUSHING IN BEHIND THE COLD FRONT MONDAY
NIGHT. H8 TEMPS DROPPING DOWN TO 1-3C WILL BE PLENTY COLD TO
GENERATE SOME ADDITIONAL LAKE EFFECT CLOUDS AND RAIN SHOWERS BEHIND
THE FRONT ON TUESDAY. THE PATTERN LOOKS PROGRESSIVE HOWEVER... AND
THE TROUGH IS EXPECTED TO KICK OUT ON TUESDAY NIGHT... WITH WARM
ADVECTION RETURNING ALREADY ON WEDNESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 757 AM EDT THU SEP 13 2012
VFR CONDITIONS ARE EXPECTED TODAY WITH CLOUD BASES GENERALLY 5-8K
FT. CIGS/VSBYS WILL LOWER INTO MVFR CATEGORY LATE TODAY AND THIS
EVENING FROM WEST TO EAST AS STEADIER RAINS MOVE IN. THE RAIN
TRAILS WELL BEHIND THE COLD FRONT... AND AT 12Z THE FRONT WAS
ORIENTED FROM ROUGHLY THE SAGINAW BAY TO SRN LK MI. SW WINDS WILL
SHIFT TO THE WEST THEN NORTHWEST AS THE VERY SLOW MOVING FRONT
PASSES THROUGH TODAY. THE FRONT WAS THROUGH MKG AT 12Z... BUT
PROBABLY WONT PASS THROUGH JXN UNTIL NEARLY 00Z TONIGHT. SFC WIND
SPEEDS COULD REACH 12-15 KTS FROM THE WEST SOUTHWEST FOR A PERIOD
TODAY AHEAD OF THE COLD FRONT... BETWEEN APPROX 15Z AND 20Z.
&&
.MARINE...
ISSUED AT 934 AM EDT THU SEP 13 2012
WE HAVE EXPANDED THE SMALL CRAFT ADVISORY NORTH TO NOW INCLUDE THE
ENTIRE NEARSHORE. WE HAVE ALSO PULLED THE STARTING TIME OF THE
ADVISORY TO THE CURRENT TIME. THE BUOY OFF OF BIG SABLE POINT
INDICATES WAVES AROUND 5 FEET OR SO THIS MORNING IMMEDIATELY BEHIND
THE COLD FRONT MOVING THROUGH. WINDS AND WAVES ARE PICKING UP ALONG
THE ENTIRE COAST...A LITTLE QUICKER THAN EARLIER ANTICIPATED. WINDS
WILL PICK UP DOWN SOUTH TODAY...AND WINDS WILL DIMINISH LATER TODAY
AND THIS EVENING UP NORTH.
WE COULD BE FLIRTING WITH ADVISORY CRITERIA ONCE AGAIN ON FRIDAY
WITH WINDS EXPECTED TO BE APPROACHING 20 KNOTS. WITH THE COOLER AIR
OVER LAKE MICHIGAN...THAT COULD HELP BUILD WAVES ONCE AGAIN. WE WILL
LET THE CURRENT ADVISORY PLAY OUT FOR NOW. WE WILL RE-EVALUATE THE
NEED LATER TO EITHER EXTEND THE CURRENT ADVISORY...OR LET IT EXPIRE
AND ISSUE A NEW ONE IF NEEDED.
&&
.HYDROLOGY...
ISSUED AT 340 AM EDT THU SEP 13 2012
MOST AREAS WILL SEE LESS THAN A HALF INCH OF RAIN LATER TODAY
THROUGH TONIGHT. THIS WILL NOT CAUSE ANY HYDRO ISSUES.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LMZ844>846.
&&
$$
UPDATE...DUKE
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...JK
MARINE...NJJ
AREA FORECAST DISCUSSION
NWS DULUTH MN
705 AM CDT THU SEP 13 2012
.AVIATION.../12Z TAF ISSUANCE/
HIGH AND MID LEVEL CLOUDS WILL PERSIST TODAY AS AN UPPER LEVEL
LOW TRACKS SOUTHEAST OVER THE REGION. WINDS WILL BECOME GUSTY
BY THIS AFTERNOON...WITH THE STRONGEST WINDS AT KBRD. A FEW LIGHT
SHOWERS WILL BE POSSIBLE LATE TODAY...MAINLY NEAR KINL TO KHIB.
SKIES WILL CLEAR AFTER MIDNIGHT WITH BUILDING HIGH PRESSURE.
&&
.PREV DISCUSSION... /ISSUED 410 AM CDT THU SEP 13 2012/
SHORT TERM..CONVEYOR BELT OF UPPER LVL MOISTURE CONTINUES TO
MOVE NORTHEAST OVER ERN HALF OF CWA...ASSOCIATED WITH FORWARD
FLANK OF 30H TROF. BDRY LYR FEATURES A CYCLONIC FLOW OF RELATIVELY
DRY AIR UNDERCUTTING MOIST AIR ALOFT. A FEW SPRINKLES OR SHOWERS
ARE POSSIBLE THROUGH EARLY MORNING OVER PRICE COUNTY. WEDGE OF VERY
DRY AIR WITHIN 925/850 LYR HAS ADVECTED INTO AREA FROM TWIN PORTS
SOUTHWEST TO BRD LAKES VICINITY. A SECONDARY COLD FRONT IS LOCATED
OVER CTRL MAN/ONTARIO WITH DECENT LOW LVL THERMAL RIBBON INDICATED
IN RAP 925 ANALYSIS. LARGE MID/UPPER LVL LOW OVER ERN SASK IS
MOVING SE WITH GRADUAL MOISTENING OF LOWER LAYERS ACROSS SRN
MAN/ONTARIO.
TODAY...UPPER LOW OVER SASK WILL TRACK TOWARDS KINL BY EARLY
EVENING. CLOUDS WILL INCREASE WITH SLGT CHC PRECIP NEAR BORDER
THIS AFTN. MAX TEMPS IN NRN LAKE/COOK COUNTIES A BIT ON THE
CHILLY SIDE. STEEPENING LAPSE RATES WITH MID LVL MOISTURE MAY
GENERATE CONSIDERABLE VIRGA TODAY ACROSS NRN HALF OF MN ZONES.
BEST FORCING WILL REMAIN NEAR SECONDARY COLD FRONT NORTH OF THE
BORDER. VERY DEEP MIXING LAYER 0F 8K TO 10K TODAY ACROSS MOST OF
THE CWA SHOULD ALLOW MOMENTUM TRANSFER AND GUSTY WINDS. GUSTS WILL
NOT BE AS HIGH AS YESTERDAY AS CORE OF STRONGER WINDS ALOFT WILL
HAVE SHIFTED EAST OF REGION. ELEVATED FIRE DANGER MAY DEVELOP OVER
SWRN/SCTRL CWA IN THE AREA OF LOWEST RH AND GUSTY WINDS.
TONIGHT...MID LVL LOW MOVES TO ERN LAKE SUPERIOR WITH DEEP LYR
DRYING EXPECTED TO COVER MOST OF CWA BY EARLY FRIDAY. SFC HIGH
WILL MOVE INTO CWA WITH WINDS SUBSIDING. LATEST SREF PLUMES
SUPPORT TEMPS IN LOW/MID 30S RANGE OVER MOST OF CWA INLAND FROM
LAKE SUPERIOR. HAVE ISSUED FROST ADVISORY FOR CWA EXCEPT NSHORE
ZONES...AND ERN MOST WISC ZONES. CLOUD COVERAGE AND MIXING WILL
BE SLOWEST TO LEAVE ERN WISC ZONES. FROST DURATION MAY BE FAIRLY
LIMITED IN MOST LOCATIONS DUE TO INITIAL CLOUD COVERAGE AND WIND.
TOMORROW...VERY PLEASANT WEATHER PATTERN AS SFC/MID LVL RIDGING
PREVAIL FOR MOST OF THE DAY. NEAR CLIMO TEMPS AND ABUNDANT SUNSHINE.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
SFC HIGH PRESSURE AND MID LEVEL RIDGING WILL PREVAIL FRIDAY
RESULTING IN A DRY DAY WITH LIGHT WINDS. A TRANSITION TO WAA AND A
SRLY FLOW IS FOUND FRIDAY NIGHT AS AN ELONGATED H85 TROUGH MOVES
INTO THE LEE OF THE ROCKIES/WESTERN DAKOTAS. THE NORTHLAND REMAINS
SITUATED AHEAD OF THE TROUGH IN THE STRONG WAA SATURDAY...ALLOWING
FOR WELL ABOVE NORMAL TEMPS...IN THE 70S TO AROUND 80...AND GUSTY
SOUTH-SOUTHWEST WINDS. THE LATEST GFS/ECM/GEM ARE SHOWING GOOD
AGREEMENT THAT H85 TEMPS COMMENCE IN THE SINGLE DIGITS FRIDAY
EVENING...REACHING THE MID AND TEENS BY SATURDAY EVENING.
TEMPERATURES WILL BE COOLER ALONG THE NORTH SHORE OF LAKE SUPERIOR
WITH A LIGHT ONSHORE WIND.
THE LONG WAVE TROUGH AND H50 VORT...ACCOMPANIED BY A STRONG SFC COLD
FRONT...WILL SWEEP SOUTHEAST OVER THE REGION SUNDAY NIGHT INTO
MONDAY. THE FROPA WILL BRING RAIN SHOWERS...GUSTY NORTHWEST
WINDS...AND MUCH COOLER TEMPERATURES. HAVE LOWERED HIGHS MONDAY INTO
THE 50S AS A POTENT CAA REGIME WILL LIMIT MUCH WARMING AND KEEP
CLOUDS AND SHOWERS AROUND. LONG TERM MODELS CONTINUE TO SHOW H85
TEMPS FALL INTO THE NEGATIVE SINGLE DIGITS WITH H50 TEMPS
APPROACHING NEGATIVE 30 ACROSS THE BORDERLAND MONDAY NIGHT. THE COLD
TEMPS...STEEP LAPSE RATES...AND H10-H50 THICKNESSES OF 530 DAM
SUPPORT A CHANCE FOR ANY LINGERING RAIN SHOWERS IN THE MN ARROWHEAD
ZONES TO MIX WITH SNOW. HOWEVER...LITTLE OR NO ACCUMULATION IS
EXPECTED.
THE NORTHLAND REMAINS UNDER THE BROAD CYCLONIC FLOW THROUGH THE
REMAINDER OF THE WEEK...KEEPING COOLER TEMPERATURES AND ONGOING
CHANCES FOR SHOWERS THROUGH THE EXTENDED. .
&&
.POINT TEMPS/POPS...
DLH 65 37 68 40 / 10 10 0 0
INL 61 34 68 37 / 20 0 0 0
BRD 67 36 72 38 / 10 0 0 0
HYR 66 32 69 36 / 10 10 0 0
ASX 67 39 68 39 / 10 10 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...FROST ADVISORY FROM 2 AM TO 8 AM CDT FRIDAY FOR MNZ010>012-018-
019-025-026-033>038.
WI...FROST ADVISORY FROM 2 AM TO 8 AM CDT FRIDAY FOR WIZ001-002-
006>008.
LS...NONE.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
649 AM CDT THU SEP 13 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
/412 AM CDT THU SEP 13 2012/
Short Range (Today through Saturday)...
Primary weather concerns are focused over the next 18 hours. By
sunrise a cold front which entered northwest MO Wednesday evening
will have made it through the entire CWA. A pronounced upper trough
over the Northern and Central Plains will slide east-southeast
through MN/IA/MO today. While there has been little to no
pre-frontal convection multi-layered frontogenesis and isentropic
ascent primarily on the 305K surface have resulted in a sw-ne
oriented band of convection from KS through IA. However, this band
has steadily narrowed and decreased in intensity since midnight.
Have placed a strong emphasis on the 00Z NAM and LSX local WRF which
projected a steady weakening of the frontogenetical forcing as well
as just about eliminating the isentropic ascent by mid morning
today. Radar trends and latest HRRR model output further support
these two models. So, have lowered pops over most areas except the
far northwestern CWA.
Would have lowered them further except for a little fly in the
ointment...layered clouds/scattered convection associated with an
upper low just south of the 4-corners area is being tapped into by
the Plains upper trough. These scattered showers are being lifted
northeast and should see some of this moisture spread into the the
west central CWA by this afternoon...and possibly reaching into
central MO by late afternoon. Have also lowered temperatures within
the expected areas of showers and decent cold air advection.
Weak high pressure will move into the Central Plains and MO on
Friday although some semblance of the upper low will be hanging
around from NM into southern KS. This creates a little uncertainty
as to how far south the clearing will push south as well as the
threat of some showers possibly reaching the far southwestern
counties. Otherwise, looking at some very pleasant weather into the
first part of the weekend.
MJ
Medium Range (Sunday through Wednesday)...
The cutoff low that forms across the southern High Plains this
weekend begins to eject eastward on Sunday, as the southwesterly jet
over the Texas Panhandle strengthens. The resultant wave appears a
bit weaker as it shifts eastward in the latest model runs, but could
still produce some widely scattered precipitation across southern
portions of the CWA on Sunday. Also on Sunday, the next deep trough
across the Northern Plains begins diving southeastward into the
forecast area, beginning the chance of precipitation across our
northwest by Sunday night. Most operational models kick this system
through fairly quickly on Monday, with the exception of the GEM and
a few of the GFS ensemble members, so have cut back precipitation
chances to the south and east on Monday night and Tuesday. Another
front will likely drop through the region sometime in the Wednesday
- Thursday timeframe again next week, and have kept in a chance of
precipitation Wednesday night when most models bring the boundary
through. Temperatures will be primarily below average through the
extended forecast, with little chance for recovery between potent
cold frontal passages.
Laflin
&&
.AVIATION...
For the 12Z TAFs...00Z NAM and latest HRRR are handling the post
frontal showers best. They favor hit and miss type showers at all 3
terminals. Showers have a better chance of becoming more numerous
early this afternoon but confidence is not overly high. So best to
handle using VCSH until/if they become more organized. Instability
is very limited so will forgo mention of thunder. Mainly MVFR
ceilings between KMCI and KSTJ which should work into KMKC. Unless
the showers become heavier not expecting IFR conditions this
morning. Shower threat should end early afternoon at KSTJ and shift
south into KC area by late afternoon with improving ceiling heights.
VFR conditions from tonight through the rest of the forecast period
with light and variable winds.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
532 AM CDT THU SEP 13 2012
.AVIATION...12Z KGRI TAF...AFTER SOME PATCHY FOG DISSIPATES THIS
MORNING...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KGRI FOR THE
REMAINDER OF THE TAF PERIOD. WHILE A FEW SPOTS ACROSS THE REGION
HAVE FALLEN INTO MVFR VSBYS EARLY THIS MORNING...JUST ENOUGH MID
LEVEL STRATUS HAS PERSISTED AT KGRI TO KEEP SIGNIFICANT FOG
FORMATION AWAY FROM THE TERMINAL. AS A RESULT...ONLY MENTIONED
SOME BR WITH VFR VSBYS THROUGH 14Z...WITH CLEARING SKIES AND
IMPROVED VISIBILITIES THEREAFTER. WITH SURFACE HIGH PRESSURE
SINKING ACROSS THE LOCAL AREA TODAY...WINDS DO NO APPEAR TO BE
MUCH OF A CONCERN...WITH WEST TO NORTHWEST WINDS LESS THAN 10KTS
EXPECTED THROUGH THE AFTERNOON HOURS.
&&
.PREV DISCUSSION... /ISSUED 408 AM CDT THU SEP 13 2012/
SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT. A RELATIVELY QUITE
PATTERN IS EXPECTED OVER THE NEXT FEW DAYS. PRECIPITATION WILL EXIT
THE OUTLOOK AREA THIS MORNING MORNING...AND THIS WILL BEGIN THE
RELATIVELY QUITE WEATHER AS HIGH PRESSURE SLIDES INTO THE REGION
FROM THE WEST.
THE LATEST RUNS OF BOTH THE NAM AND RUC SUGGEST PRECIPITATION ENDING
ACROSS THE CWA BY MID TO LATE MORNING. FURTHERMORE...THE HRRR ALSO
DEPICTS DRY CONDITIONS BY MID MORNING...SO WENT AHEAD AND SPLIT THE
12Z TO 18Z BLOCK INTO TWO 3 HOUR GROUPS TO ACCOUNT FOR THE
PRECIPITATION ENDING EARLIER THAN PREVIOUSLY FORECAST THIS
MORNING.
WITH LIGHT WINDS AND SUBSIDENCE EXPECTED BEHIND THE EXITING
STRATUS...THERE WILL BE A CHANCE FOR SOME PATCHY FOG EARLY THIS
MORNING...ESPECIALLY NORTHWESTERN PARTS OF THE CWA IF ENOUGH
CLEARING CAN OCCUR BEFORE DAYTIME HEATING BEGINS. CONFIDENCE IS NOT
HIGH ENOUGH TO GO WITH A PRE-FIRST PERIOD AS MOST SPOTS SHOULD BE
ABOVE 3 MILES OF VISIBILITY BY 12Z. NOT GOING TO INCLUDE THE
MENTIONING OF FOG AT THIS TIME BUT THOUGHT IT WAS WORTH MENTIONING.
GOING TO LEAVE IT IN THE GRIDS THOUGH.
THE BIGGEST FORECAST CHALLENGE FOR THE REST OF THE SHORT TERM WILL
BE TEMPERATURES. TEMPERATURES ON FRIDAY WERE NOTICEABLY DIFFERENT
THAN PREVIOUSLY FORECAST...WITH HIGHS 3 TO 4 DEGREES WARMER IN MOST
LOCATIONS. FRIDAY MORNING LOW TEMPERATURES WERE ALSO 3 TO 4 DEGREES
WARMER IN MOST LOCATIONS. THE THOUGHT BEHIND THESE HIGHER
TEMPERATURES IS MOST LIKELY GUIDANCE KEYING ON HIGHER DEWPOINTS FROM
THE RECENT RAINFALL...MOSTLY CLEAR SKIES...AND ADIABATIC COMPRESSION
FROM THE WESTERLY WIND COMPONENT. THE LATEST RUN OF THE NAM12 ALSO
DEPICTS WARM AIR ADVECTION AT 850MB AS OPPOSED TO PREVIOUS RUNS...SO
WENT AHEAD AND RAISED TEMPERATURES A FEW DEGREES TO ACCOUNT FOR THIS
WARMER SETUP. THIS WAS THE BIGGEST CHANGE DURING THIS PERIOD.
OVERALL...NEAR SEASONABLE TEMPERATURES AND DRY CONDITIONS WILL BE
EXPERIENCED BOTH FRIDAY AND SATURDAY.
LONG TERM...SUNDAY THROUGH WEDNESDAY...A BEAUTIFUL END OF THE
WEEKEND APPEARS TO BE ON TAP FOR THE REGION SUNDAY AS SEASONABLY
WARM TEMPERATURES...LIGHT SOUTHERLY WINDS....AND ONLY A FEW HIGH
CLOUDS ARE EXPECTED AHEAD OF AN APPROACHING FRONTAL BOUNDARY. THIS
FRONTAL BOUNDARY WILL BE STEERED ACROSS THE PLAINS SUNDAY NIGHT
THROUGH MONDAY BY AN UPPER LEVEL SHORTWAVE...WITH A MARKEDLY COOLER
AIRMASS EXPECTED IN ITS WAKE AS 850MB TEMPS AREA FORECAST TO DROP
8-10C BEHINDS THIS FRONT. WHILE THERE WILL ALSO BE A CHANCE FOR A
FEW SHOWERS AND EVEN AN ISOLATED THUNDERSTORM LATE SUNDAY NIGHT
THROUGH MONDAY EVENING...THE BEST UPPER LEVEL FORCING APPEARS TO BE
TO DIRECTED THE NORTHEAST OF THE LOCAL AREA IN BOTH LATEST RUNS OF
THE GFS AND EC...AND DECIDED TO TONE DOWN PRECIP CHANCES ACCORDINGLY
OVER THIS TIME PERIOD AS A DEVELOPING UPPER LEVEL RIDGE ACROSS THE
WESTERN STATES APPEARS TO BE SHIFTING THE FOCUS OF THIS SYSTEM AWAY
FROM THE AREA.
THEREAFTER...A GENERALLY NORTHWESTERLY UPPER LEVEL FLOW PATTERN IS
PROGGED TO KEEP MAIN FOCUS OF WEATHER ACROSS THE CENTER OF THE
COUNTRY THROUGH MID WEEK...WITH SEASONABLY COOL TEMPERATURES
EXPECTED AGAIN ON TUESDAY...WITH A BRIEF WARMING TO NEAR OR ABOVE
CLIMO WEDNESDAY...AHEAD OF THE NEXT APPROACHING COLD FRONT. WHILE
MODELS WERE TRYING TO KEY IN ON SOME SMALL CHANCE POPS WITH THIS
NEXT BOUNDARY WED/WED NIGHT...WITH PERSISTENT UPPER LEVEL RIDGE OVER
THE WEST COAST AND CORRESPONDING FOCUS OF STORM TRACK TO OUR
EAST...NOT TO MENTION VERY LIMITED LOW LEVEL MOISTURE...WENT AHEAD
AND REMOVED SMALL CHANCE POPS FROM THE FORECAST WITH THIS SECOND
FRONT MID WEEK IN COORDINATION WITH SURROUNDING OFFICES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...GUERRERO
LONG TERM/AVIATION...ROSSI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
618 AM CDT THU SEP 13 2012
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
307 AM CDT THU SEP 13 2012
MAIN FORECAST CONCERNS ARE ON TIMING THE END OF ONGOING
PRECIPITATION...POTENTIAL FOR FROST AND VALLEY FOG TONIGHT...AND
POSSIBLE FIRE WEATHER CONCERNS FOR SATURDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO SOUTHWEST CANADA...
TROUGHING FROM SOUTH CENTRAL CANADA INTO NEBRASKA...AND RIDGING
ALONG THE EAST COAST. WITHIN THE UPPER TROUGHING...NOTABLE FEATURES
INCLUDE A SHORTWAVE OVER NORTHWEST IOWA AND AN UPPER LOW OVER
CENTRAL SASKATCHEWAN. THE FORECAST AREA RESIDES IN SOUTHWEST FLOW
AHEAD OF THE NORTHWEST IOWA SHORTWAVE...AS WELL AS IN A RIGHT
ENTRANCE REGION OF A 100-120KT JET AT THE TROPOPAUSE EXTENDING
FROM CENTRAL MINNESOTA INTO NORTHERN ONTARIO. THE FORECAST AREA
ALSO RESIDES IN A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH
SHOWS UP IN 700MB PROFILER DATA AS WELL AS IN 850MB TEMPS FROM 00Z
RAOBS (8C AT MPX COMPARED TO 13C AT GRB AND 16C AT DVN). THE
COMBINATION OF ALL THESE FORCING FEATURES RESULTING IN A BAND OF
SHOWERS FROM THE OKLAHOMA AND TEXAS PANHANDLES NORTHEASTWARD TO LA
CROSSE AND INTO EASTERN UPPER MICHIGAN. BACK EDGE OF SHOWERS WAS
NEAR ALBERT LEA AND DODGE CENTER MN. BACK EDGE OF THE CIRRUS CLOUD
COVER WAS QUITE A BIT FARTHER NORTHWEST...THOUGH...NEAR ST CLOUD.
PLENTY OF LOW LEVEL DRY AIR ALSO TO THE NORTHWEST...NOTED BY
SURFACE DEWPOINTS IN THE TEENS AND LOW 20S ACROSS NORTH DAKOTA TO
ALEXANDRIA MN. GOES SOUNDER PRECIPITABLE WATER IMAGERY DEPICTING
VALUES AROUND 0.3 INCHES OVER NORTH DAKOTA...OR ABOUT 50 PERCENT
OF NORMAL.
TODAY AND TONIGHT...AFTER MUCH STRUGGLES THE PAST COUPLE DAYS WITH
THE UPPER LOW IN SASKATCHEWAN...MODELS ARE ALL NOW IN SYNC WITH
BASICALLY WHAT THE OUTLIER 11.00Z NAM SUGGESTED. MODELS DROP THE
UPPER LOW INTO THE MEAN TROUGHING... REACHING NORTHERN MINNESOTA
BY 00Z. THE UPPER LOW THEN RAPIDLY HEADS EAST TO NORTHERN LOWER
MICHIGAN BY 12Z FRIDAY. MEANWHILE...THE NORTHWEST IOWA SHORTWAVE
IS PROGGED TO MOVE NORTHEAST THROUGH THE FORECAST AREA DURING THE
DAY TODAY. THE COMBINATION OF THE UPPER LOW AND IOWA SHORTWAVE WILL
PUSH THE FRONTOGENESIS ZONE AND ITS ASSOCIATED SHOWERS EAST OUT OF
THE FORECAST AREA. TIMING WISE...MOST OF THE AREA SHOULD BE DRY
AFTER 18Z. IN ADDITION...AS THE UPPER LOW APPROACHES...DRIER AIR
AND CLEARING SEEN OFF TO OUR NORTHWEST OVER THE DAKOTAS AND
NORTHWEST MINNESOTA WILL ADVECT IN. PREVIOUSLY THERE WAS CONCERN
ABOUT THE UPPER LOW DROPPING INTO MINNESOTA BRINGING SOME ISOLATED
PRECIPITATION TO THE AREA. HOWEVER...NOW THAT MODELS ARE TRACKING
THE UPPER LOW SO FAR NORTH...AND ITS TIMING DOES NOT COINCIDE WITH
PEAK HEATING...NOT ANTICIPATING ANY PRECIPITATION WITH IT.
THEREFORE...DRY CONDITIONS ARE EXPECTED ONCE THE PRECIPITATION
ASSOCIATED WITH THE FRONTOGENESIS ENDS. IN FACT...INDICATIONS ARE
THAT MUCH OF THE FORECAST AREA WILL BE CLEAR TONIGHT. WITH
PRECIPITABLE WATER VALUES DROPPING TO 0.3-0.4 INCHES AND LIGHT
WINDS ASSOCIATED WITH HIGH PRESSURE OVERHEAD AFTER MIDNIGHT...
TEMPERATURES ARE GOING TO TANK. HAVE LEANED TOWARDS THE COLDER OF
GUIDANCE...DROPPING THE TYPICAL COLD SPOTS IN WISCONSIN TO NEAR
FREEZING WITH MID 30S TO MID 40S ELSEWHERE. PATCHY FROST LOOKS
LIKELY ACROSS TAYLOR...CLARK... JACKSON...MONROE...JUNEAU AND
ADAMS COUNTIES. APPEARS FROST COVERAGE RIGHT NOW SHOULD STAY LOW
ENOUGH TO PRECLUDE THE NEED FOR ANY ADVISORY. WITH RECENT RAINS
AND LATE IN THE DAY CLEARING...VALLEY FOG ALSO LOOKS LIKELY FOR
THE WISCONSIN RIVER VALLEY AND MISSISSIPPI RIVER TRIBUTARIES. THE
MAIN MISSISSIPPI VALLEY HAS A CONCERN WITH THE DRY AIR
IMPACT...GIVEN THAT TEMP/DEWPOINT SPREADS OF AT LEAST 30F ARE
POSSIBLE BY LATE THIS AFTERNOON. LIGHT WINDS EXTENDING UP A FEW
THOUSAND FEET AND RECENT RAIN SHOULD ALLOW GOOD DEWPOINT RECOVERY
THIS EVENING...BUT WHETHER IT IS ENOUGH IS UNCERTAIN. THEREFORE...
HAVE KEPT THE MISSISSIPPI RIVER VALLEY AT PATCHY FOG FOR THE
PRESENT TIME.
FRIDAY THROUGH SATURDAY NIGHT...MODELS SHOW THAT THE RIDGING
CURRENTLY OVER SOUTHWEST CANADA WILL BREAK DOWN...IN RESPONSE TO
TROUGHING OVER THE GULF OF ALASKA PUSHING EAST. AS SUCH...WE SHOULD
SEE THE FLOW OVER THE NORTHERN U.S. TURN MORE ZONAL....ALLOWING SOME
WARMER AIR THAT GETS DOWNSLOPED OFF THE ROCKIES TO PUSH INTO THE
FORECAST AREA. THERE ARE INDICATIONS THAT TOWARDS LATE SATURDAY
NIGHT SOME WEAK RIDGING WILL BUILD OVER THE WESTERN GREAT LAKES...IN
RESPONSE TO THE GULF OF ALASKA TROUGHING STALLING OVER CENTRAL
CANADA. EXPECT A COLD FRONT TO SEPARATE THE TROUGHING/RIDGING
INTERFACE...WHICH BY 12Z SUNDAY WILL EXTEND FROM NORTHWEST ONTARIO
SOUTHWEST INTO CENTRAL SOUTH DAKOTA. PLENTY OF DRY AIR FROM THE
LOW TO UPPER LEVELS OF THE TROPOSPHERE AHEAD OF THE FRONT IS
EXPECTED TO PRODUCE CLEAR SKIES FOR MUCH OF THIS PERIOD. A
TIGHTENING PRESSURE GRADIENT AHEAD OF THE FRONT SHOULD HELP TO
INCREASE THE WINDS OVER THE FORECAST AREA...BEGINNING FRIDAY NIGHT
AND ESPECIALLY FOR SATURDAY AND SATURDAY NIGHT. WITH MORE
WIND...AS WELL AS PRECIPITABLE WATER VALUES PROGGED TO CLIMB TO
AROUND 0.5 INCHES... ANTICIPATE WARMER LOWS FOR FRIDAY NIGHT AND
THUS LITTLE CONCERN FOR FOG OR FROST. 850MB TEMPS OF 8-10C ON
FRIDAY SHOULD ALLOW FOR HIGHS IN THE LOWER 70S. ON SATURDAY...
THOSE 850MB TEMPS CLIMB TO 11-13C AND WITH THE INCREASING
SOUTHWEST WIND...TEMPERATURES SHOULD TOP OUT IN THE MID TO UPPER
70S. A FEW LOCATIONS MAY EVEN REACH 80. MAY HAVE TO WATCH FIRE
WEATHER CONDITIONS FOR SATURDAY. SEE FIRE WEATHER DISCUSSION
BELOW. EVEN WARMER LOWS EXPECTED SATURDAY NIGHT WITH A SOUTHWEST
BREEZE CONTINUING...THOUGH THE DRY AIR LIKELY ALLOWING SOME OF THE
TYPICAL COLD SPOTS TO DROP INTO THE LOW TO MID 40S.
.LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT
307 AM CDT THU SEP 13 2012
13.00Z ECMWF/GFS/UKMET AND GFS ENSEMBLES ARE IN EXCELLENT AGREEMENT
ON A MAJOR PATTERN SHIFT FOR THE LONG TERM PERIOD. THE 13.00Z
CANADIAN HAS THE PATTERN SHIFT TOO...BUT WILL BE DISCOUNTED AS AN
OUTLIER SINCE THE POSITION OF THE UPPER TROUGHING COME 00Z TUESDAY
AND ESPECIALLY BY 00Z WEDNESDAY DOES NOT AGREE WITH THE
AFOREMENTIONED MODELS.
ON SUNDAY...RIDGING REALLY AMPLIFIES OVER FAR WESTERN CANADA. IN
TURN...THIS FORCES A DEEPENING TROUGH DOWNSTREAM...WHICH DIGS DOWN
INTO THE NORTHERN PLAINS SUNDAY NIGHT. THIS TROUGH DIGGING DOWN
SHOULD HELP PUSH EASTWARD THE COLD FRONT THAT WAS OVER SOUTH DAKOTA
12Z SUNDAY. IT APPEARS THE FRONT WILL CROSS THE FORECAST AREA SUNDAY
NIGHT. PRIOR TO THE FRONTAL PASSAGE...SUNDAY SHOULD BE ANOTHER WARM
DAY WITH 850MB TEMPS OF 12-14C AND PLENTY OF SUN. HIGHS ARE LIKELY
TO BE EQUAL TO OR SLIGHTLY HIGHER THAN SATURDAY. ANOTHER
FRONTOGENETIC BAND OF PRECIPITATION LOOKS TO DEVELOP ON THE COOL
SIDE OF THE FRONT. THEREFORE...40-60 PERCENT CHANCES OF PRECIPITATION
EXIST ACROSS THE FORECAST AREA FOR BOTH SUNDAY NIGHT AND MONDAY.
FUTURE SHIFTS MAY BE ABLE TO INCREASE THESE MORE. ADDED A LOW
CHANCE OF THUNDER AS WELL GIVEN MUCAPE FORECASTS OF 300 J/KG OR SO
WITH THE FRONTOGENESIS BAND. THE UPPER TROUGH LOOKS TO DIG INTO
THE AREA FOR MONDAY NIGHT AND TUESDAY. COMBINATION OF COOL
TEMPERATURES ALOFT AND ANY SHORTWAVES MOVING THROUGH THE TROUGH
RESULTS IN THE NEED TO MAINTAIN 20-30 PERCENT CHANCES DURING THIS
TIME FRAME. A BRIEF BREAK IN PRECIPITATION IS ANTICIPATED TUESDAY
NIGHT...THEN MODELS HAVE ANOTHER POTENT SHORTWAVE DROPPING DOWN
INTO THE NORTHERN PLAINS ON WEDNESDAY. SOME WARM ADVECTION AND
DPVA FORCED PRECIPITATION IS POSSIBLE AHEAD OF IT...THOUGH
AVAILABLE MOISTURE IS A QUESTION MARK...THUS CONSENSUS 20 PERCENT
CHANCES ARE WARRANTED.
AS THE UPPER TROUGH DROPS INTO THE AREA ON MONDAY...850MB TEMPS
REALLY TUMBLE. BY 00Z TUESDAY...THEY ARE FORECAST DOWN TO AT LEAST
3-6C AND MAY EVEN FALL A LITTLE MORE...ESPECIALLY AS WE HEAD TO 12Z
TUESDAY. AS A RESULT...BOTH MONDAY AND TUESDAY LOOK CHILLY WITH
HIGHS IN THE 60S MONDAY AND 50S TUESDAY. 850MB TEMPS SHOULD WARM
BACK UP TUESDAY NIGHT INTO WEDNESDAY...PERHAPS PEAKING AS HIGH AS
8-11C PER 13.00Z ECMWF...IN RESPONSE TO THE NEXT POTENT SHORTWAVE
DROPPING THROUGH THE TROUGH. THEREFORE...HIGHS SHOULD CLIMB BACK
INTO THE 60S FOR WEDNESDAY.
FOR THOSE LOOKING FARTHER OUT...IT APPEARS THE MEAN UPPER TROUGHING
WILL STAY IN PLACE AND PERHAPS EVEN AMPLIFY THROUGH THE END OF NEXT
WEEK...PER THE 13.00Z ECMWF/GFS. THIS IS ALSO IN GOOD AGREEMENT WITH
THE 12.00Z CFS WHICH HAS BEEN SHOWING A CONSISTENT SIGNAL OF
BELOW NORMAL TEMPERATURES FOR THE LATTER HALF OF SEPTEMBER OVER
THE CENTRAL AND EASTERN PORTION OF THE U.S.
&&
.AVIATION...TODAY THROUGH FRIDAY MORNING
618 AM CDT THU SEP 13 2012
GOOD VFR CONDITIONS TO PREVAIL AT THE TAF SITES THIS PERIOD...BUT
FOR FRONT AND TAIL ENDS OF THE PERIOD AT KLSE.
THE COLD FRONT AND BAND OF POST-FRONT -RA WILL CONTINUE TO MOVE
SOUTH/EAST OF THE AREA THIS MORNING. IT APPEAR THE -RA WILL MOVE
EAST OF KLSE AROUND 13Z. THE MID CLOUD WAS EXITING KRST AND WILL
MOVE EAST OF KLSE DURING THE MID-MORNING HOURS...LEAVING ONLY
SCT-BKN HIGH CLOUDS INTO THE EARLY AFTERNOON HOURS AS DRIER HIGH
PRESSURE MOVED INTO THE UPPER MIDWEST BEHIND THE COLD FRONT.
THE HIGH WILL BRING MOSTLY CLEAR SKIES...LIGHT WINDS AND COOL TEMPS
TO THE AREA TONIGHT...A FAVORABLE SET-UP FOR LATE NIGHT/EARLY
MORNING VALLEY FOG. BIG QUESTION IS HOW MUCH BOUNDARY LAYER DRYING
WILL SPREAD INTO THE AREA TODAY. PLENTY OF DRY AIR UPSTREAM OVER ND
AND NORTHERN MN EARLY THIS MORNING WITH SFC DEW POINTS IN THE UPPER
20S/30S. THIS AIRMASS EXPECTED TO ADVECT INTO THE AREA TODAY...BUT
THE RECENT RAINS AND GENERALLY LIGHT WINDS MAY PREVENT DEW POINTS
FROM DROPPING MUCH BELOW THE LOWER 40S...THEN ALLOWING THE DEW
POINTS TO RISE A BIT THIS EVENING AND END UP NEAR THE EXPECTED LOWS.
HAVE INTRODUCED BCFG TO KLSE TAF AFTER 08Z FOR NOW WITH PLENTY OF
UNCERTAINTY WITH THE SFC DEW POINT TRENDS TODAY. 00Z TAF SET THIS
EVENING SHOULD BE ABLE TO ADD MORE DETAIL TO THE OVERNIGHT FOG
THREAT IN THE MS/WI RIVER VALLEYS.
&&
.FIRE WEATHER...FRIDAY AND SATURDAY
307 AM CDT THU SEP 13 2012
ON FRIDAY...HIGH PRESSURE OVERHEAD COMBINED WITH PLENTY OF DRY AIR
WILL RESULT IN RELATIVE HUMIDITY VALUES DROPPING TO AROUND 25
PERCENT ACROSS MUCH OF THE AREA. RECENT RAINS PLUS WINDS LESS THAN
10 MPH SHOULD PRECLUDE ANY FIRE WEATHER CONCERNS...THOUGH THE DRY
AIR AND FULL SUNSHINE WILL HELP TO DRY OUT FUELS.
ON SATURDAY...THE COMBINATION OF SOUTHWEST WINDS INCREASE TO 10 TO
15 MPH WITH HIGHER GUSTS...ALONG WITH PLENTY OF DRY AIR IN THE
ATMOSPHERE ALLOWING FOR GOOD MIXING SHOULD SEND RELATIVE HUMIDITY
VALUES PLUMMETING TO 25 TO 30 PERCENT IN THE AFTERNOON. LOWEST
RELATIVE HUMIDITY VALUES AND HIGHEST WINDS LOOK TO OCCUR WEST OF THE
MISSISSIPPI RIVER. IN ADDITION...HIGH TEMPERATURES ARE EXPECTED TO
TOP OUT IN THE MID TO UPPER 70S. WILL HAVE TO WAIT AND SEE HOW MUCH
THE FUELS DRY OUT OVER THE NEXT TWO DAYS...BUT AT LEAST WEATHER WISE
THERE IS SOME CONCERN FOR INCREASED WILDFIRE POTENTIAL. THE CONCERN
WOULD ONLY INCREASE WITH A LITTLE MORE WIND AND/OR LOWER RELATIVE
HUMIDITY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
307 AM CDT THU SEP 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM.....AJ
LONG TERM......AJ
AVIATION.......RRS
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
352 PM CDT THU SEP 13 2012
...UPDATED SHORT TERM SECTION...
.SYNOPSIS...
ISSUED AT 1151 AM CDT THU SEP 13 2012
LATE MORNING WATER VAPOR LOOP AND RAP ANALYSIS SHOWED THE NORTHERN
STREAM MID LEVEL TROUGH AXIS MOVING INTO THE UPPER GREAT LAKES
REGION...WHICH EXTENDED SOUTHWEST INTO WESTERN KANSAS...MEETING A
DISTURBANCE WITH SUBTROPICAL CHARACTERISTICS OVER CENTRAL NEW
MEXICO. 12Z 700MB RAOB ANALYSIS SHOWED DEWPOINTS OF 4 TO 6 DEGC AT
EL PASO, MIDLAND, AMARILLO TX AND NORMAN, OK. THE SURFACE COLD FRONT
TIED TO THE OLD STORM THAT MOVED ACROSS CANADA OVER THE LAST COUPLE
OF DAYS HAD PUSHED WELL INTO TEXAS EXTENDING FROM JUST NORTH OF DEL
RIO TO AROUND MINERAL WELLS, TX AT 13Z. A 1031MB SURFACE HIGH WAS
ANALYZED ON THE 13Z ANALYSIS WITH TEMPERATURES BOTTOMING OUT IN THE
MID TO UPPER 30S ACROSS THE SAND HILLS OF NEBRASKA (NORTH PLATTE, NE
HAD A LOW OF 35 DEGREES). THE PRECIPITATION EVENT WHICH WAS TIED TO
THE MID LEVEL FRONTOGENETIC ZONE CONTINUED FROM PORTIONS OF WEST AND
NORTHWEST TEXAS INTO WESTERN OKLAHOMA AND SOUTH CENTRAL KANSAS. MORE
SPECIFICALLY CLOSER TO HOME AS OF 16Z...THE BACK EDGE OF THE
PRECIPITATION EXTENDED FROM BEAVER, OK TO GREENSBURG, KS TO GREAT
BEND, KS. LOW CLOUDS WERE DISSIPATING NOT TOO FAR NORTHWEST OF THIS
LINE...HOWEVER HIGH LEVEL CLOUD COVER CONTINUED ALL THE WAY
NORTHWEST TO A LAMAR, CO TO MCCOOK, NE LINE.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 351 PM CDT THU SEP 13 2012
THE NORTHWEST EDGE OF THE PRECIPITATION AREA WILL SLOWLY SHIFT
SOUTHEAST THROUGH THE EVENING...AND PER LATEST HIGH RESOLUTION
SIMULATED REFLECTIVITY PROGS...SHOULD BE EXITING COMANCHE AND BARBER
COUNTIES BY AROUND 03Z THIS EVENING. A COMPLICATING FACTOR HOWEVER
IS THE SPIN-UP OF THE MID LEVEL VORTICITY CENTER OVER WEST TEXAS
TONIGHT INTO EARLY FRIDAY...WHICH WILL ACT TO HALT THE 700-500MB
DEFORMATION ZONE...AND PERHAPS SHIFT IT BACK NORTHWARD 30 OR SO
MILES. WILL HAVE TO KEEP SOME CHANCE POPS IN THE FAR SOUTH CENTRAL
KANSAS AREAS...MAINLY SOUTHEASTERN CLARK AND SOUTHERN COMANCHE AND
BARBER COUNTIES. THERE WILL BE A GRADIENT IN CLOUD COVER AS
WELL...WITH SKY CLEARING QUICKLY NORTH OF THE PRECIPITATION AREA.
THE CLEARED OUT AREAS WILL SEE WINDS DIMINISHING TO LESS THAN 8
KNOTS TONIGHT AS 1030MB SURFACE HIGH SHIFTS SOUTH INTO WEST CENTRAL
KANSAS BY 12Z FRIDAY. GIVEN THE COOL START TO THE `TONIGHT`
PERIOD...SHOULD SEE TEMPERATURES BOTTOM OUT IN THE 43 TO 46F RANGE
OVER MANY AREAS NORTHWEST OF A HUGOTON TO DODGE CITY TO LARNED
LINE. IT WON`T BE SURPRISING TO SEE SOME CREEK/STREAM VALLEY AREAS
SEE LOWS DOWN TO AROUND 40...ESPECIALLY IN THE SYRACUSE TO SCOTT
CITY TO COLLYER AREAS. DEWPOINTS WILL BE FALLING INTO THE 30S...SO
THE PROBABILITY OF LOWER VISIBILITIES AT DAYBREAK WILL BE FAIRLY
LOW...AND FOG FORMATION DOES NOT APPEAR LIKELY.
ON FRIDAY...WILL CONTINUE THE NOTION OF WARMER NORTH...COOLER SOUTH
WITH HIGHS FRIDAY NEAR THE OKLAHOMA BORDER FROM MEADE STATE PARK TO
KIOWA IN THE MID TO UPPER 60S. AREAS ALONG I-70 SHOULD SEE
AFTERNOON TEMPERATURES PEAKING IN THE UPPER 70S UNDER MOSTLY CLEAR
SKY. THE SURFACE RIDGE AXIS WILL REMAIN CONFINED TO A
WEST-SOUTHWEST TO EAST NORTHEAST AXIS ACROSS KANSAS WITH LIGHT WINDS
THROUGHOUT THE DAY FRIDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 123 PM CDT THU SEP 13 2012
MEDIUM RANGE MODELS INDICATE A POSITIVELY TILTED UPPER LEVEL
TROUGH OF LOW PRESSURE STRETCHED ACROSS THE SOUTH PLAINS AND
PORTIONS OF THE DESERT SOUTHWEST EARLY IN THE PERIOD FRIDAY NIGHT.
THE UPPER LEVEL TROUGH IS PROGGED TO BEGIN PUSHING SLOWLY EASTWARD
ACROSS WEST TEXAS THROUGHOUT THE WEEKEND KEEPING ANY PRECIP CHANCES
JUST OFF TO OUR SOUTH AND SOUTHEAST ACROSS OKLAHOMA AND TEXAS. ALONG
WITH A LACK OF AVAILABLE LOW LEVEL MOISTURE, LOOK FOR MOSTLY DRY
CONDITIONS TO PREVAIL ACROSS WESTERN KANSAS THROUGH AT LEAST SUNDAY
NIGHT. THE GFS, GEM, AND ECMWF THEN GENERALLY SHOW A LARGE SCALE
UPPER LEVEL TROUGH DROPPING SOUTH OUT OF CANADA INTO THE NORTHERN
PLAINS AND THE EXTREME WESTERN GREAT LAKES REGION EARLY NEXT WEEK
THIS WILL BRING THE POSSIBILITY FOR PRECIP TO THE CENTRAL PLAINS,
INCLUDING PORTIONS OF CENTRAL AND WESTERN KANSAS, AS AN ATTENDANT
COLD FRONT SURGES SOUTHWARD INTO THE REGION. THE PRIMARY ISSUES
THIS FAR OUT THOUGH INCLUDE THE TIMING AND STRENGTH OF THE SYSTEM
AS WELL AS THE AVAILABILITY OF LOW/MID LEVEL MOISTURE FOR THE
SYSTEM TO WORK WITH. DUE TO THIS UNCERTAINTY, SLIGHT POPS REMAIN
REASONABLE FOR MONDAY.
TEMPERATURES WILL BE NEAR NORMAL SATURDAY AS THE WARMING TREND
CONTINUES INTO THE WEEKEND. FOR SATURDAY, A LEE SIDE TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP ACROSS EASTERN COLORADO HELPING TO
INFLUENCE MORE OF A SOUTHERLY FLOW ACROSS WESTERN KANSAS. THIS
WILL DRAW SLIGHTLY WARMER AIR INTO THE AREA WITH H85 TEMPERATURES
RANGING FROM THE MID TEENS(C) ACROSS CENTRAL KANSAS TO NEAR 20C
ALONG THE COLORADO BORDER. WIDESPREAD 70S(F) CAN BE EXPECTED
SATURDAY AFTERNOON WITH NEAR 80F NOT OUT OF THE QUESTION.
SOUTHERLY WINDS WILL CONTINUE ACROSS WESTERN KANSAS SUNDAY HELPING
TO ADVECT WARMER AIR NORTHWARD INTO THE STATE. THE GEM, GFS AND
ECMWF SHOW H85 TEMPERATURES RANGING FROM THE UPPER TEENS(C) TO
NEAR 20C ACROSS CENTRAL KANSAS TO NEAR 25C IN FAR SOUTHWEST KANSAS.
ALONG WITH PLENTY OF SUNSHINE EXPECTED, LOOK FOR HIGHS UP INTO THE
LOW TO MID 80S(F) SUNDAY AFTERNOON. COOLER TEMPERATURES ARE LIKELY
EARLY NEXT WEEK AS A RESULT OF THE COLD FRONT PROJECTED TO DROP
SOUTHWARD INTO WESTERN KANSAS SOMETIME EARLY TO MID DAY MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1151 AM CDT THU SEP 13 2012
CEILING HAD IMPROVED AT GCK AND HYS AS SUBSIDENCE WAS BUILDING SOUTH
WITH THE STORM SYSTEM MOVING AWAY. DDC CONTINUED WITH MVFR CEILING
AS OF 16Z...HOWEVER THIS CEILING WILL SCATTER OUT BY EARLY AFTERNOON
WITH VFR CONDITIONS TAKING OVER FROM EARLY AFTERNOON THROUGH TONIGHT
AND BEYOND. WINDS WILL SLOWLY DECREASE TO 8 TO 10 KNOTS BY LATE THIS
AFTERNOON/EARLY THIS EVENING...AND CONTINUE TO DECREASE TO AROUND 5
TO 7 KNOTS THROUGH THE NIGHT TONIGHT. AT THIS TIME...NO REDUCTION IN
VISIBILITY IS EXPECTED DURING THE DAYBREAK TIME FRAME EARLY FRIDAY
MORNING DESPITE TEMPERATURES LIKELY BOTTOMING OUT AROUND THE MID 40S.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 45 73 46 76 / 10 0 0 0
GCK 43 74 46 77 / 10 0 0 0
EHA 46 71 46 77 / 10 0 0 0
LBL 47 70 47 76 / 10 0 0 0
HYS 44 77 46 77 / 10 0 0 0
P28 49 65 50 75 / 40 20 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...JJOHNSON
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
133 PM CDT THU SEP 13 2012
...UPDATE TO LONG TERM...
.SYNOPSIS...
ISSUED AT 1151 AM CDT THU SEP 13 2012
LATE MORNING WATER VAPOR LOOP AND RAP ANALYSIS SHOWED THE NORTHERN
STREAM MID LEVEL TROUGH AXIS MOVING INTO THE UPPER GREAT LAKES
REGION...WHICH EXTENDED SOUTHWEST INTO WESTERN KANSAS...MEETING A
DISTURBANCE WITH SUBTROPICAL CHARACTERISTICS OVER CENTRAL NEW
MEXICO. 12Z 700MB RAOB ANALYSIS SHOWED DEWPOINTS OF 4 TO 6 DEGC AT
EL PASO, MIDLAND, AMARILLO TX AND NORMAN, OK. THE SURFACE COLD FRONT
TIED TO THE OLD STORM THAT MOVED ACROSS CANADA OVER THE LAST COUPLE
OF DAYS HAD PUSHED WELL INTO TEXAS EXTENDING FROM JUST NORTH OF DEL
RIO TO AROUND MINERAL WELLS, TX AT 13Z. A 1031MB SURFACE HIGH WAS
ANALYZED ON THE 13Z ANALYSIS WITH TEMPERATURES BOTTOMING OUT IN THE
MID TO UPPER 30S ACROSS THE SAND HILLS OF NEBRASKA (NORTH PLATTE, NE
HAD A LOW OF 35 DEGREES). THE PRECIPITATION EVENT WHICH WAS TIED TO
THE MID LEVEL FRONTOGENETIC ZONE CONTINUED FROM PORTIONS OF WEST AND
NORTHWEST TEXAS INTO WESTERN OKLAHOMA AND SOUTH CENTRAL KANSAS. MORE
SPECIFICALLY CLOSER TO HOME AS OF 16Z...THE BACK EDGE OF THE
PRECIPITATION EXTENDED FROM BEAVER, OK TO GREENSBURG, KS TO GREAT
BEND, KS. LOW CLOUDS WERE DISSIPATING NOT TOO FAR NORTHWEST OF THIS
LINE...HOWEVER HIGH LEVEL CLOUD COVER CONTINUED ALL THE WAY
NORTHWEST TO A LAMAR, CO TO MCCOOK, NE LINE.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 313 AM CDT THU SEP 13 2012
THE AFOREMENTIONED TROUGH WILL CONTINUE TO DRIVE THE SENSIBLE
WEATHER ACROSS WESTERN AND CENTRAL KANSAS FOR THE NEXT 18 HOURS.
INITIALLY, THE CURRENT RAIN BAND WILL ADVECT SLOWLY EASTWARD, BEING
MAINTAINED BY PERSISTENT ISENTROPIC LIFT WITHIN THE TROUGH AXIS.
THE ISENTROPIC DOWNWARD OMEGA ZONE WILL APPROXIMATE THE BACK EDGE
OF THE SHOWER BAND, AND WILL PROBABLY BE LOCATED FROM ABOUT A HAYS
TO GARDEN CITY AND HUGOTON LINE BY 12 UTC. THE ISENTROPIC LIFT ZONE
WILL THEN SLOWLY PERSIST EASTWARD INTO SOUTH CENTRAL KANSAS INTO
THIS EVENING, BRINGING THE ENTIRE AREA MEASURABLE RAINFALL BETWEEN
TWO TENTHS AND A HALF INCH (AND LOCALLY HIGHER AMOUNTS). ALTHOUGH
THE CURRENT RADAR RETURNS ARE SLOWLY DIMINISHING, THE MODELS
CONTINUE TO DEVELOP ADDITIONAL ISENTROPIC LIFT PRECIPITATION LATER
THIS MORNING. OVERNIGHT LOWS COULD BECOME A CHALLENGE TONIGHT. THE
NAM IS SIGNIFICANTLY WARMER THAN WHAT THE CURRENT FORECAST DATABASE
HAD INDICATED, POSSIBLY DUE TO AN AIRMASS CHANGE THAT WILL OCCUR
BEHIND THE TROUGH. THE AIR WON`T BE THE SAME RAIN COOLED AIRMASS
FROM THE DAY, AND THESE WARMER TEMPERATURES ARE PLAUSIBLE. STRATUS
COULD REDEVELOP ANYWHERE ACROSS CENTRAL KANSAS AS WELL BUT THE
NORTHEAST WIND TRAJECTORIES DON`T SEEM TO HEAVILY FAVOR WIDESPREAD
FOG. WE WILL PROBABLY HEDGE LOW TEMPERATURES SOMEWHERE BETWEEN THE
TWO SOLUTIONS AT THIS POINT.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 123 PM CDT THU SEP 13 2012
MEDIUM RANGE MODELS INDICATE A POSITIVELY TILTED UPPER LEVEL
TROUGH OF LOW PRESSURE STRETCHED ACROSS THE SOUTH PLAINS AND
PORTIONS OF THE DESERT SOUTHWEST EARLY IN THE PERIOD FRIDAY NIGHT.
THE UPPER LEVEL TROUGH IS PROGGED TO BEGIN PUSHING SLOWLY EASTWARD
ACROSS WEST TEXAS THROUGHOUT THE WEEKEND KEEPING ANY PRECIP CHANCES
JUST OFF TO OUR SOUTH AND SOUTHEAST ACROSS OKLAHOMA AND TEXAS. ALONG
WITH A LACK OF AVAILABLE LOW LEVEL MOISTURE, LOOK FOR MOSTLY DRY
CONDITIONS TO PREVAIL ACROSS WESTERN KANSAS THROUGH AT LEAST SUNDAY
NIGHT. THE GFS, GEM, AND ECMWF THEN GENERALLY SHOW A LARGE SCALE
UPPER LEVEL TROUGH DROPPING SOUTH OUT OF CANADA INTO THE NORTHERN
PLAINS AND THE EXTREME WESTERN GREAT LAKES REGION EARLY NEXT WEEK
THIS WILL BRING THE POSSIBILITY FOR PRECIP TO THE CENTRAL PLAINS,
INCLUDING PORTIONS OF CENTRAL AND WESTERN KANSAS, AS AN ATTENDANT
COLD FRONT SURGES SOUTHWARD INTO THE REGION. THE PRIMARY ISSUES
THIS FAR OUT THOUGH INCLUDE THE TIMING AND STRENGTH OF THE SYSTEM
AS WELL AS THE AVAILABILITY OF LOW/MID LEVEL MOISTURE FOR THE
SYSTEM TO WORK WITH. DUE TO THIS UNCERTAINTY, SLIGHT POPS REMAIN
REASONABLE FOR MONDAY.
TEMPERATURES WILL BE NEAR NORMAL SATURDAY AS THE WARMING TREND
CONTINUES INTO THE WEEKEND. FOR SATURDAY, A LEE SIDE TROUGH OF LOW
PRESSURE IS EXPECTED TO DEVELOP ACROSS EASTERN COLORADO HELPING TO
INFLUENCE MORE OF A SOUTHERLY FLOW ACROSS WESTERN KANSAS. THIS
WILL DRAW SLIGHTLY WARMER AIR INTO THE AREA WITH H85 TEMPERATURES
RANGING FROM THE MID TEENS(C) ACROSS CENTRAL KANSAS TO NEAR 20C
ALONG THE COLORADO BORDER. WIDESPREAD 70S(F) CAN BE EXPECTED
SATURDAY AFTERNOON WITH NEAR 80F NOT OUT OF THE QUESTION.
SOUTHERLY WINDS WILL CONTINUE ACROSS WESTERN KANSAS SUNDAY HELPING
TO ADVECT WARMER AIR NORTHWARD INTO THE STATE. THE GEM, GFS AND
ECMWF SHOW H85 TEMPERATURES RANGING FROM THE UPPER TEENS(C) TO
NEAR 20C ACROSS CENTRAL KANSAS TO NEAR 25C IN FAR SOUTHWEST KANSAS.
ALONG WITH PLENTY OF SUNSHINE EXPECTED, LOOK FOR HIGHS UP INTO THE
LOW TO MID 80S(F) SUNDAY AFTERNOON. COOLER TEMPERATURES ARE LIKELY
EARLY NEXT WEEK AS A RESULT OF THE COLD FRONT PROJECTED TO DROP
SOUTHWARD INTO WESTERN KANSAS SOMETIME EARLY TO MID DAY MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1151 AM CDT THU SEP 13 2012
CEILING HAD IMPROVED AT GCK AND HYS AS SUBSIDENCE WAS BUILDING SOUTH
WITH THE STORM SYSTEM MOVING AWAY. DDC CONTINUED WITH MVFR CEILING
AS OF 16Z...HOWEVER THIS CEILING WILL SCATTER OUT BY EARLY AFTERNOON
WITH VFR CONDITIONS TAKING OVER FROM EARLY AFTERNOON THROUGH TONIGHT
AND BEYOND. WINDS WILL SLOWLY DECREASE TO 8 TO 10 KNOTS BY LATE THIS
AFTERNOON/EARLY THIS EVENING...AND CONTINUE TO DECREASE TO AROUND 5
TO 7 KNOTS THROUGH THE NIGHT TONIGHT. AT THIS TIME...NO REDUCTION IN
VISIBILITY IS EXPECTED DURING THE DAYBREAK TIME FRAME EARLY FRIDAY
MORNING DESPITE TEMPERATURES LIKELY BOTTOMING OUT AROUND THE MID 40S.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 47 73 48 76 / 10 0 0 0
GCK 44 74 48 77 / 10 0 0 0
EHA 46 71 48 77 / 10 0 0 0
LBL 48 70 49 76 / 10 0 0 0
HYS 44 77 48 77 / 10 0 0 0
P28 51 65 52 75 / 30 20 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...RUSSELL
LONG TERM...JJOHNSON
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1152 AM CDT THU SEP 13 2012
...UPDATED AVIATION AND SYNOPSIS SECTIONS...
.SYNOPSIS...
ISSUED AT 1151 AM CDT THU SEP 13 2012
LATE MORNING WATER VAPOR LOOP AND RAP ANALYSIS SHOWED THE NORTHERN
STREAM MID LEVEL TROUGH AXIS MOVING INTO THE UPPER GREAT LAKES
REGION...WHICH EXTENDED SOUTHWEST INTO WESTERN KANSAS...MEETING A
DISTURBANCE WITH SUBTROPICAL CHARACTERISTICS OVER CENTRAL NEW
MEXICO. 12Z 700MB RAOB ANALYSIS SHOWED DEWPOINTS OF 4 TO 6 DEGC AT
EL PASO, MIDLAND, AMARILLO TX AND NORMAN, OK. THE SURFACE COLD FRONT
TIED TO THE OLD STORM THAT MOVED ACROSS CANADA OVER THE LAST COUPLE
OF DAYS HAD PUSHED WELL INTO TEXAS EXTENDING FROM JUST NORTH OF DEL
RIO TO AROUND MINERAL WELLS, TX AT 13Z. A 1031MB SURFACE HIGH WAS
ANALYZED ON THE 13Z ANALYSIS WITH TEMPERATURES BOTTOMING OUT IN THE
MID TO UPPER 30S ACROSS THE SAND HILLS OF NEBRASKA (NORTH PLATTE, NE
HAD A LOW OF 35 DEGREES). THE PRECIPITATION EVENT WHICH WAS TIED TO
THE MID LEVEL FRONTOGENETIC ZONE CONTINUED FROM PORTIONS OF WEST AND
NORTHWEST TEXAS INTO WESTERN OKLAHOMA AND SOUTH CENTRAL KANSAS. MORE
SPECIFICALLY CLOSER TO HOME AS OF 16Z...THE BACK EDGE OF THE
PRECIPITATION EXTENDED FROM BEAVER, OK TO GREENSBURG, KS TO GREAT
BEND, KS. LOW CLOUDS WERE DISSIPATING NOT TOO FAR NORTHWEST OF THIS
LINE...HOWEVER HIGH LEVEL CLOUD COVER CONTINUED ALL THE WAY
NORTHWEST TO A LAMAR, CO TO MCCOOK, NE LINE.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 313 AM CDT THU SEP 13 2012
THE AFOREMENTIONED TROUGH WILL CONTINUE TO DRIVE THE SENSIBLE
WEATHER ACROSS WESTERN AND CENTRAL KANSAS FOR THE NEXT 18 HOURS.
INITIALLY, THE CURRENT RAIN BAND WILL ADVECT SLOWLY EASTWARD, BEING
MAINTAINED BY PERSISTENT ISENTROPIC LIFT WITHIN THE TROUGH AXIS.
THE ISENTROPIC DOWNWARD OMEGA ZONE WILL APPROXIMATE THE BACK EDGE
OF THE SHOWER BAND, AND WILL PROBABLY BE LOCATED FROM ABOUT A HAYS
TO GARDEN CITY AND HUGOTON LINE BY 12 UTC. THE ISENTROPIC LIFT ZONE
WILL THEN SLOWLY PERSIST EASTWARD INTO SOUTH CENTRAL KANSAS INTO
THIS EVENING, BRINGING THE ENTIRE AREA MEASURABLE RAINFALL BETWEEN
TWO TENTHS AND A HALF INCH (AND LOCALLY HIGHER AMOUNTS). ALTHOUGH
THE CURRENT RADAR RETURNS ARE SLOWLY DIMINISHING, THE MODELS
CONTINUE TO DEVELOP ADDITIONAL ISENTROPIC LIFT PRECIPITATION LATER
THIS MORNING. OVERNIGHT LOWS COULD BECOME A CHALLENGE TONIGHT. THE
NAM IS SIGNIFICANTLY WARMER THAN WHAT THE CURRENT FORECAST DATABASE
HAD INDICATED, POSSIBLY DUE TO AN AIRMASS CHANGE THAT WILL OCCUR
BEHIND THE TROUGH. THE AIR WON`T BE THE SAME RAIN COOLED AIRMASS
FROM THE DAY, AND THESE WARMER TEMPERATURES ARE PLAUSIBLE. STRATUS
COULD REDEVELOP ANYWHERE ACROSS CENTRAL KANSAS AS WELL BUT THE
NORTHEAST WIND TRAJECTORIES DON`T SEEM TO HEAVILY FAVOR WIDESPREAD
FOG. WE WILL PROBABLY HEDGE LOW TEMPERATURES SOMEWHERE BETWEEN THE
TWO SOLUTIONS AT THIS POINT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 313 AM CDT THU SEP 13 2012
FOR FRIDAY A LINGERING UPPER LOW OVER CENTRAL KANSAS COULD KEEP SOME
LINGERING LIGHT RAIN SHOWERS IN OUR SOUTHEASTERN FA FROM COLDWATER
TO PRATT AND COOLER HIGH TEMPERATURES. THEN FOR SATURDAY AS THE
UPPER LOW MOVES EAST INTO THE OHIO VALLEY SOUTH WINDS RETURN WITH A
WARM FRONT MOVING ACROSS WESTERN KANSAS ON SUNDAY AHEAD OF AN UPPER
LEVEL SHORTWAVE TROUGH MOVING INTO THE NORTHERN PLAINS. A STRONG
UPPER LEVEL TROUGH THEN DIGS INTO THE CENTRAL PLAINS ON MONDAY
BRINGING A COLD FRONT ACROSS WESTERN KANSAS. WILL KEEP A SMALL POP
FOR SHOWERS AND THUNDERSTORMS WITH AND BEHIND THE COLD FRONT FOR
MONDAY. THE STRONG UPPER LOW AND TROUGH MOVE EAST INTO THE UPPER
MIDWEST AND OHIO VALLEY ON TUESDAY WHILE THE NEW CANADIAN HAS A LONG
WAVE TROUGH LINGERING FROM THE NORTHERN PLAINS INTO THE SOUTHERN
PLAINS. THE CANADIAN MODEL LOOKS TO BE THE ODD MODEL OUT AT THIS
TIME COMPARED TO THE GFS AND ECMWF. THEN FOR WEDNESDAY ANOTHER UPPER
LEVEL SHORTWAVE TROUGH MOVES OUT OF CENTRAL CANADA AND INTO THE
NORTHERN PLAINS. ANOTHER WARM UP IS FORECAST AHEAD OF THE WAVE ON
WEDNESDAY.
OVERNIGHT LOWS FALL INTO THE 40S ON SATURDAY MORNING THEN WARM INTO
THE 50S THROUGH THE MIDDLE OF NEXT WEEK. DAYTIME HIGHS LOOK TO WARM
FROM AROUND 70 ON FRIDAY TO THE LOW TO MID 80S ON SUNDAY WITH A WARM
FRONT. ON MONDAY A COLD FRONT WILL LOWER HIGHS INTO THE 70S WITH A
GRADUAL WARMING TREND INTO NEXT WEDNESDAY BACK INTO THE 80S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1151 AM CDT THU SEP 13 2012
CEILING HAD IMPROVED AT GCK AND HYS AS SUBSIDENCE WAS BUILDING SOUTH
WITH THE STORM SYSTEM MOVING AWAY. DDC CONTINUED WITH MVFR CEILING
AS OF 16Z...HOWEVER THIS CEILING WILL SCATTER OUT BY EARLY AFTERNOON
WITH VFR CONDITIONS TAKING OVER FROM EARLY AFTERNOON THROUGH TONIGHT
AND BEYOND. WINDS WILL SLOWLY DECREASE TO 8 TO 10 KNOTS BY LATE THIS
AFTERNOON/EARLY THIS EVENING...AND CONTINUE TO DECREASE TO AROUND 5
TO 7 KNOTS THROUGH THE NIGHT TONIGHT. AT THIS TIME...NO REDUCTION IN
VISIBILITY IS EXPECTED DURING THE DAYBREAK TIME FRAME EARLY FRIDAY
MORNING DESPITE TEMPERATURES LIKELY BOTTOMING OUT AROUND THE MID 40S.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 62 50 69 48 / 20 10 0 0
GCK 64 47 71 48 / 10 10 0 0
EHA 62 48 71 48 / 10 10 0 0
LBL 61 49 69 49 / 20 10 0 0
HYS 65 47 72 48 / 10 10 0 0
P28 58 50 68 52 / 100 30 20 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...RUSSELL
LONG TERM...KRUSE
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
427 PM EDT THU SEP 13 2012
.SYNOPSIS...
ISSUED AT 427 PM EDT THU SEP 13 2012
A COLD FRONT WILL BRING RAIN TO THE AREA OVERNIGHT. THIS WILL BE
FOLLOWED BY COOLER BUT STILL SEASONABLE TEMPERATURES AROUND 70 ON
FRIDAY. AFTER A GRADUAL WARMING TREND TO THE MID 70S THROUGH
MONDAY...ANOTHER COLD FRONT WILL BRING A CHANCE FOR RAIN SHOWERS
MONDAY NIGHT AND TUESDAY ALONG WITH HIGH TEMPERATURES IN THE 60S.
&&
.UPDATE...
ISSUED AT 424 PM EDT THU SEP 13 2012
FORECAST WAS UPDATED TO ACCOUNT FOR THE SHOWERS DEVELOPING FROM
LANSING TO NEAR KALAMAZOO.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 335 PM EDT THU SEP 13 2012
TREND ON THE RAIN FOR TONIGHT HAS BEEN DOWN IN TERMS OF AMOUNTS FOR
SEVERAL MODEL RUNS NOW. REGIONAL RADAR LOOPS DO NOT LOOK OVERLY
IMPRESSIVE EITHER. STILL...EXPECT A BAND OF RAIN TO WORK THROUGH THE
ENTIRE FORECAST AREA BRINGING AMOUNTS ON THE ORDER OF A TENTH OR TWO
AT MOST LOCATIONS. THE FAR SOUTHEAST TOWARD JACKSON MAY SEE SLIGHTLY
HIGHER AMOUNTS. PRECIPITATION IS BEING FOCUSED BY THE RIGHT ENTRANCE
REGION OF A 300MB JET. CURRENT THINKING BASED ON SPC AND NSSL WRF
MODEL RUNS AND THE TRENDS IN THE LATEST HRRR IS THAT THE RAIN WILL
BE OFF TO THE EAST OF THE FORECAST AREA BY 12Z ON FRIDAY.
LOOKING FOR SOME MORNING CUMULUS DEVELOPMENT ON FRIDAY WITH DRIER
AIR TAKING OVER DURING THE AFTERNOON. IN GENERAL EXPECTING A PARTLY
CLOUDY TO MOSTLY SUNNY FORECAST FOR FRIDAY. FEEL THE AIR MASS
WILL BE TOO DRY FOR ANY SHOWER DEVELOPMENT OFF THE LAKE DESPITE
DELTA T/S IN THE MIDDLE TEENS C.
FRIDAY NIGHT THROUGH SATURDAY NIGHT LOOKS QUIET AND DRY WITH HIGH
PRESSURE IN CONTROL.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 335 PM EDT THU SEP 13 2012
FAIR WX WITH SEASONABLY MILD TEMPS IS ANTICIPATED SUNDAY THROUGH
MONDAY AFTERNOON IN A SOUTHERLY FLOW WAA PATTERN IN ADVANCE OF THE
APPROACHING COLD FRONT. THAT FRONT WILL BRING SOME SHOWERS MONDAY
NIGHT THROUGH TUESDAY. LAKE EFFECT CLOUDS AND SHOWERS ARE
ANTICIPATED TUESDAY NIGHT INTO WEDNESDAY AS H8 TEMPS (BRIEFLY) DIP
DOWN TO AROUND 0 TO -1 C BEFORE MODERATING.
IT WILL TURN COOLER TUESDAY THROUGH MIDWEEK AS A FAIRLY DEEP
LONGWAVE UPPER LEVEL TROUGH DEVELOPS FROM THE UPPER MIDWEST TO GREAT
LAKES REGIONS. A SECONDARY COLD FRONT WILL BRING THE CHANCE FOR
ADDITIONAL SHOWERS WEDNESDAY NIGHT THROUGH THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1200 PM EDT THU SEP 13 2012
VFR CONDITIONS THIS AFTERNOON WILL GRADUALLY TRANSITION TO MVFR
TONIGHT AS LOW CLOUDS AND A BAND OF SHOWERS GRADUALLY MOVE IN FROM
THE WEST. SHOWERS SHOULD REACH KMKG BY LATE AFTN AND THE REST OF THE
TERMINALS THIS EVENING. CONDITIONS WILL GRADUALLY IMPROVE BACK TO
VFR FRIDAY MORNING AS THE LOWER CLOUDS AND SHOWERS EXIT THE AREA. NW
WINDS WILL RAMP UP TO 10-15 KTS BY LATE FRIDAY MORNING AS CLOUDS
SCATTER OUT BEFORE SKIES EVENTUALLY CLEAR.
&&
.MARINE...
ISSUED AT 335 PM EDT THU SEP 13 2012
HAVE OPTED TO KEEP THE CURRENT CONFIGURATION TO THE SMALL CRAFT
ADVISORIES WITH THE NORTH ENDING THIS EVENING AND THE SOUTH
OVERNIGHT. GRADIENT TURNS LAX TONIGHT IN THE WAKE OF FIRST FRONTAL
PASSAGE WHICH LEADS TO A DECAYING WAVE FIELD. WINDS INCREASE AGAIN
ON FRIDAY THOUGH IN THE WAKE OF A SECONDARY FRONT LATE TONIGHT.
WINDS WILL LIKELY NOSE UP TOWARDS 20 KNOTS FRIDAY WHICH SHOULD BUILD
A SOLID 3-5 FOOT WAVE FIELD DURING THE DAY. SO...RATHER THAN STRETCH
THE CURRENT SCA THROUGH TOMORROW THROUGH A 8-12 PERIOD OF QUIET
WAVES LATE TONIGHT AND TOMORROW MORNING OPTED TO LET THE CURRENT
HEADLINES EXPIRE TONIGHT. A NEW SCA WILL LIKELY BE NEED FOR FRIDAY
WITH THE OVERNIGHT FORECAST PACKAGE IF THE CURRENT FORECAST WINDS
HOLD.
&&
.HYDROLOGY...
ISSUED AT 335 PM EDT THU SEP 13 2012
NO HYDRO ISSUES ANTICIPATED WITH RAINFALL AMOUNTS PROBABLY ENDING UP
BELOW A THIRD OF AN INCH IN MANY AREAS TONIGHT. HIGHEST AMOUNTS WILL
BE IN THE FAR SOUTHEAST REACHES OF THE FORECAST AREA TOWARDS
JACKSON. RIVER LEVELS ARE LOW AND WELL WITHIN BANK. THE NEXT CHANCE
FOR RAIN DOES NOT COME UNTIL EARLY NEXT WEEK AFTER TONIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LMZ844>846.
&&
$$
UPDATE...MJS
SYNOPSIS...TJT
SHORT TERM...DUKE
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...DUKE
MARINE...DUKE
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
425 PM EDT THU SEP 13 2012
.SYNOPSIS...
ISSUED AT 335 PM EDT THU SEP 13 2012
A COLD FRONT WILL MOVE SOUTH OF THE STATE OF MICHIGAN TONIGHT
USHERING IN A COOLER AIR MASS. HIGHS FRIDAY...SATURDAY AND SUNDAY
WILL WARM A BIT EACH DAY WITH FRIDAY HIGHS ONLY AROUND 70...SATURDAY
IN THE LOWER 70S AND SUNDAY PUSHING INTO THE MIDDLE 70S. THE WEEKEND
IS EXPECTED TO BE DRY WITH A GOOD DEAL OF SUNSHINE. A BAND OF RAIN
WILL MOVE THROUGH THE AREA THIS EVENING AND OVERNIGHT. IT SHOULD BE
EAST OF LANSING AND JACKSON BY ABOUT SUNRISE ON FRIDAY.
&&
.UPDATE...
ISSUED AT 424 PM EDT THU SEP 13 2012
FORECAST WAS UPDATED TO ACCOUNT FOR THE SHOWERS DEVELOPING FROM
LANSING TO NEAR KALAMAZOO.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 335 PM EDT THU SEP 13 2012
TREND ON THE RAIN FOR TONIGHT HAS BEEN DOWN IN TERMS OF AMOUNTS FOR
SEVERAL MODEL RUNS NOW. REGIONAL RADAR LOOPS DO NOT LOOK OVERLY
IMPRESSIVE EITHER. STILL...EXPECT A BAND OF RAIN TO WORK THROUGH THE
ENTIRE FORECAST AREA BRINGING AMOUNTS ON THE ORDER OF A TENTH OR TWO
AT MOST LOCATIONS. THE FAR SOUTHEAST TOWARD JACKSON MAY SEE SLIGHTLY
HIGHER AMOUNTS. PRECIPITATION IS BEING FOCUSED BY THE RIGHT ENTRANCE
REGION OF A 300MB JET. CURRENT THINKING BASED ON SPC AND NSSL WRF
MODEL RUNS AND THE TRENDS IN THE LATEST HRRR IS THAT THE RAIN WILL
BE OFF TO THE EAST OF THE FORECAST AREA BY 12Z ON FRIDAY.
LOOKING FOR SOME MORNING CUMULUS DEVELOPMENT ON FRIDAY WITH DRIER
AIR TAKING OVER DURING THE AFTERNOON. IN GENERAL EXPECTING A PARTLY
CLOUDY TO MOSTLY SUNNY FORECAST FOR FRIDAY. FEEL THE AIR MASS
WILL BE TOO DRY FOR ANY SHOWER DEVELOPMENT OFF THE LAKE DESPITE
DELTA T/S IN THE MIDDLE TEENS C.
FRIDAY NIGHT THROUGH SATURDAY NIGHT LOOKS QUIET AND DRY WITH HIGH
PRESSURE IN CONTROL.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 335 PM EDT THU SEP 13 2012
FAIR WX WITH SEASONABLY MILD TEMPS IS ANTICIPATED SUNDAY THROUGH
MONDAY AFTERNOON IN A SOUTHERLY FLOW WAA PATTERN IN ADVANCE OF THE
APPROACHING COLD FRONT. THAT FRONT WILL BRING SOME SHOWERS MONDAY
NIGHT THROUGH TUESDAY. LAKE EFFECT CLOUDS AND SHOWERS ARE
ANTICIPATED TUESDAY NIGHT INTO WEDNESDAY AS H8 TEMPS (BRIEFLY) DIP
DOWN TO AROUND 0 TO -1 C BEFORE MODERATING.
IT WILL TURN COOLER TUESDAY THROUGH MIDWEEK AS A FAIRLY DEEP
LONGWAVE UPPER LEVEL TROUGH DEVELOPS FROM THE UPPER MIDWEST TO GREAT
LAKES REGIONS. A SECONDARY COLD FRONT WILL BRING THE CHANCE FOR
ADDITIONAL SHOWERS WEDNESDAY NIGHT THROUGH THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1200 PM EDT THU SEP 13 2012
VFR CONDITIONS THIS AFTERNOON WILL GRADUALLY TRANSITION TO MVFR
TONIGHT AS LOW CLOUDS AND A BAND OF SHOWERS GRADUALLY MOVE IN FROM
THE WEST. SHOWERS SHOULD REACH KMKG BY LATE AFTN AND THE REST OF THE
TERMINALS THIS EVENING. CONDITIONS WILL GRADUALLY IMPROVE BACK TO
VFR FRIDAY MORNING AS THE LOWER CLOUDS AND SHOWERS EXIT THE AREA. NW
WINDS WILL RAMP UP TO 10-15 KTS BY LATE FRIDAY MORNING AS CLOUDS
SCATTER OUT BEFORE SKIES EVENTUALLY CLEAR.
&&
.MARINE...
ISSUED AT 335 PM EDT THU SEP 13 2012
HAVE OPTED TO KEEP THE CURRENT CONFIGURATION TO THE SMALL CRAFT
ADVISORIES WITH THE NORTH ENDING THIS EVENING AND THE SOUTH
OVERNIGHT. GRADIENT TURNS LAX TONIGHT IN THE WAKE OF FIRST FRONTAL
PASSAGE WHICH LEADS TO A DECAYING WAVE FIELD. WINDS INCREASE AGAIN
ON FRIDAY THOUGH IN THE WAKE OF A SECONDARY FRONT LATE TONIGHT.
WINDS WILL LIKELY NOSE UP TOWARDS 20 KNOTS FRIDAY WHICH SHOULD BUILD
A SOLID 3-5 FOOT WAVE FIELD DURING THE DAY. SO...RATHER THAN STRETCH
THE CURRENT SCA THROUGH TOMORROW THROUGH A 8-12 PERIOD OF QUIET
WAVES LATE TONIGHT AND TOMORROW MORNING OPTED TO LET THE CURRENT
HEADLINES EXPIRE TONIGHT. A NEW SCA WILL LIKELY BE NEED FOR FRIDAY
WITH THE OVERNIGHT FORECAST PACKAGE IF THE CURRENT FORECAST WINDS
HOLD.
&&
.HYDROLOGY...
ISSUED AT 335 PM EDT THU SEP 13 2012
NO HYDRO ISSUES ANTICIPATED WITH RAINFALL AMOUNTS PROBABLY ENDING UP
BELOW A THIRD OF AN INCH IN MANY AREAS TONIGHT. HIGHEST AMOUNTS WILL
BE IN THE FAR SOUTHEAST REACHES OF THE FORECAST AREA TOWARDS
JACKSON. RIVER LEVELS ARE LOW AND WELL WITHIN BANK. THE NEXT CHANCE
FOR RAIN DOES NOT COME UNTIL EARLY NEXT WEEK AFTER TONIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LMZ844>846.
&&
$$
UPDATE...MJS
SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...DUKE
MARINE...DUKE
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
335 PM EDT THU SEP 13 2012
.SYNOPSIS...
ISSUED AT 335 PM EDT THU SEP 13 2012
A COLD FRONT WILL MOVE SOUTH OF THE STATE OF MICHIGAN TONIGHT
USHERING IN A COOLER AIR MASS. HIGHS FRIDAY...SATURDAY AND SUNDAY
WILL WARM A BIT EACH DAY WITH FRIDAY HIGHS ONLY AROUND 70...SATURDAY
IN THE LOWER 70S AND SUNDAY PUSHING INTO THE MIDDLE 70S. THE WEEKEND
IS EXPECTED TO BE DRY WITH A GOOD DEAL OF SUNSHINE. A BAND OF RAIN
WILL MOVE THROUGH THE AREA THIS EVENING AND OVERNIGHT. IT SHOULD BE
EAST OF LANSING AND JACKSON BY ABOUT SUNRISE ON FRIDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 335 PM EDT THU SEP 13 2012
TREND ON THE RAIN FOR TONIGHT HAS BEEN DOWN IN TERMS OF AMOUNTS FOR
SEVERAL MODEL RUNS NOW. REGIONAL RADAR LOOPS DO NOT LOOK OVERLY
IMPRESSIVE EITHER. STILL...EXPECT A BAND OF RAIN TO WORK THROUGH THE
ENTIRE FORECAST AREA BRINGING AMOUNTS ON THE ORDER OF A TENTH OR TWO
AT MOST LOCATIONS. THE FAR SOUTHEAST TOWARD JACKSON MAY SEE SLIGHTLY
HIGHER AMOUNTS. PRECIPITATION IS BEING FOCUSED BY THE RIGHT ENTRANCE
REGION OF A 300MB JET. CURRENT THINKING BASED ON SPC AND NSSL WRF
MODEL RUNS AND THE TRENDS IN THE LATEST HRRR IS THAT THE RAIN WILL
BE OFF TO THE EAST OF THE FORECAST AREA BY 12Z ON FRIDAY.
LOOKING FOR SOME MORNING CUMULUS DEVELOPMENT ON FRIDAY WITH DRIER
AIR TAKING OVER DURING THE AFTERNOON. IN GENERAL EXPECTING A PARTLY
CLOUDY TO MOSTLY SUNNY FORECAST FOR FRIDAY. FEEL THE AIR MASS
WILL BE TOO DRY FOR ANY SHOWER DEVELOPMENT OFF THE LAKE DESPITE
DELTA T/S IN THE MIDDLE TEENS C.
FRIDAY NIGHT THROUGH SATURDAY NIGHT LOOKS QUIET AND DRY WITH HIGH
PRESSURE IN CONTROL.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 335 PM EDT THU SEP 13 2012
FAIR WX WITH SEASONABLY MILD TEMPS IS ANTICIPATED SUNDAY THROUGH
MONDAY AFTERNOON IN A SOUTHERLY FLOW WAA PATTERN IN ADVANCE OF THE
APPROACHING COLD FRONT. THAT FRONT WILL BRING SOME SHOWERS MONDAY
NIGHT THROUGH TUESDAY. LAKE EFFECT CLOUDS AND SHOWERS ARE
ANTICIPATED TUESDAY NIGHT INTO WEDNESDAY AS H8 TEMPS (BRIEFLY) DIP
DOWN TO AROUND 0 TO -1 C BEFORE MODERATING.
IT WILL TURN COOLER TUESDAY THROUGH MIDWEEK AS A FAIRLY DEEP
LONGWAVE UPPER LEVEL TROUGH DEVELOPS FROM THE UPPER MIDWEST TO GREAT
LAKES REGIONS. A SECONDARY COLD FRONT WILL BRING THE CHANCE FOR
ADDITIONAL SHOWERS WEDNESDAY NIGHT THROUGH THURSDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1200 PM EDT THU SEP 13 2012
VFR CONDITIONS THIS AFTERNOON WILL GRADUALLY TRANSITION TO MVFR
TONIGHT AS LOW CLOUDS AND A BAND OF SHOWERS GRADUALLY MOVE IN FROM
THE WEST. SHOWERS SHOULD REACH KMKG BY LATE AFTN AND THE REST OF THE
TERMINALS THIS EVENING. CONDITIONS WILL GRADUALLY IMPROVE BACK TO
VFR FRIDAY MORNING AS THE LOWER CLOUDS AND SHOWERS EXIT THE AREA. NW
WINDS WILL RAMP UP TO 10-15 KTS BY LATE FRIDAY MORNING AS CLOUDS
SCATTER OUT BEFORE SKIES EVENTUALLY CLEAR.
&&
.MARINE...
ISSUED AT 335 PM EDT THU SEP 13 2012
HAVE OPTED TO KEEP THE CURRENT CONFIGURATION TO THE SMALL CRAFT
ADVISORIES WITH THE NORTH ENDING THIS EVENING AND THE SOUTH
OVERNIGHT. GRADIENT TURNS LAX TONIGHT IN THE WAKE OF FIRST FRONTAL
PASSAGE WHICH LEADS TO A DECAYING WAVE FIELD. WINDS INCREASE AGAIN
ON FRIDAY THOUGH IN THE WAKE OF A SECONDARY FRONT LATE TONIGHT.
WINDS WILL LIKELY NOSE UP TOWARDS 20 KNOTS FRIDAY WHICH SHOULD BUILD
A SOLID 3-5 FOOT WAVE FIELD DURING THE DAY. SO...RATHER THAN STRETCH
THE CURRENT SCA THROUGH TOMORROW THROUGH A 8-12 PERIOD OF QUIET
WAVES LATE TONIGHT AND TOMORROW MORNING OPTED TO LET THE CURRENT
HEADLINES EXPIRE TONIGHT. A NEW SCA WILL LIKELY BE NEED FOR FRIDAY
WITH THE OVERNIGHT FORECAST PACKAGE IF THE CURRENT FORECAST WINDS
HOLD.
&&
.HYDROLOGY...
ISSUED AT 335 PM EDT THU SEP 13 2012
NO HYDRO ISSUES ANTICIPATED WITH RAINFALL AMOUNTS PROBABLY ENDING UP
BELOW A THIRD OF AN INCH IN MANY AREAS TONIGHT. HIGHEST AMOUNTS WILL
BE IN THE FAR SOUTHEAST REACHES OF THE FORECAST AREA TOWARDS
JACKSON. RIVER LEVELS ARE LOW AND WELL WITHIN BANK. THE NEXT CHANCE
FOR RAIN DOES NOT COME UNTIL EARLY NEXT WEEK AFTER TONIGHT.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
LMZ847>849.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR LMZ844>846.
&&
$$
SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...DUKE
MARINE...DUKE
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1234 PM CDT Thu Sep 13 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
/412 AM CDT THU SEP 13 2012/
Short Range (Today through Saturday)...
Primary weather concerns are focused over the next 18 hours. By
sunrise a cold front which entered northwest MO Wednesday evening
will have made it through the entire CWA. A pronounced upper trough
over the Northern and Central Plains will slide east-southeast
through MN/IA/MO today. While there has been little to no
pre-frontal convection multi-layered frontogenesis and isentropic
ascent primarily on the 305K surface have resulted in a sw-ne
oriented band of convection from KS through IA. However, this band
has steadily narrowed and decreased in intensity since midnight.
Have placed a strong emphasis on the 00Z NAM and LSX local WRF which
projected a steady weakening of the frontogenetical forcing as well
as just about eliminating the isentropic ascent by mid morning
today. Radar trends and latest HRRR model output further support
these two models. So, have lowered pops over most areas except the
far northwestern CWA.
Would have lowered them further except for a little fly in the
ointment...layered clouds/scattered convection associated with an
upper low just south of the 4-corners area is being tapped into by
the Plains upper trough. These scattered showers are being lifted
northeast and should see some of this moisture spread into the the
west central CWA by this afternoon...and possibly reaching into
central MO by late afternoon. Have also lowered temperatures within
the expected areas of showers and decent cold air advection.
Weak high pressure will move into the Central Plains and MO on
Friday although some semblance of the upper low will be hanging
around from NM into southern KS. This creates a little uncertainty
as to how far south the clearing will push south as well as the
threat of some showers possibly reaching the far southwestern
counties. Otherwise, looking at some very pleasant weather into the
first part of the weekend.
MJ
Medium Range (Sunday through Wednesday)...
The cutoff low that forms across the southern High Plains this
weekend begins to eject eastward on Sunday, as the southwesterly jet
over the Texas Panhandle strengthens. The resultant wave appears a
bit weaker as it shifts eastward in the latest model runs, but could
still produce some widely scattered precipitation across southern
portions of the CWA on Sunday. Also on Sunday, the next deep trough
across the Northern Plains begins diving southeastward into the
forecast area, beginning the chance of precipitation across our
northwest by Sunday night. Most operational models kick this system
through fairly quickly on Monday, with the exception of the GEM and
a few of the GFS ensemble members, so have cut back precipitation
chances to the south and east on Monday night and Tuesday. Another
front will likely drop through the region sometime in the Wednesday
- Thursday timeframe again next week, and have kept in a chance of
precipitation Wednesday night when most models bring the boundary
through. Temperatures will be primarily below average through the
extended forecast, with little chance for recovery between potent
cold frontal passages.
Laflin
&&
.AVIATION...
For the 18Z TAFs...Axis of showers is slowly settling southeast
behind the cold front that drove south through Kansas and Missouri
overnight. Gusty 10 to 15 knot northeast winds behind the front continue
to advect in sufficiently dry air to keep ceilings in the MVFR
category this afternoon, though visibilities will likely be reduced
for brief periods as heavier showers occur along the leading edge of
the advancing moisture axis. By this evening ceilings will be going
up as more dry air moves in behind the front, with winds turning to
due east Friday morning.
Cutter
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1259 PM CDT THU SEP 13 2012
.UPDATE...UPDATED THE FORECAST FOR SKY COVER. HIGH LEVEL CLOUDS
ARE LINGERING A BIT LONGER AND HAVE INDICATED THAT IN THIS
FORECAST.
&&
.AVIATION...18Z KGRI TAF. VFR CONDITIONS ARE ANTICIPATED. WIND
WILL BE LIGHT AND VARIABLE FOR TONIGHT AS SURFACE HIGH PRESSURE
SETTLES IN. HIGH LEVEL CLOUDINESS WILL EVENTUALLY DISSIPATE AS THE
COLD FRONT SLIDES SOUTHEAST AND THE 1030 MB SURFACE HIGH BUILDS
IN. WIND WILL TURN MORE SOUTH SOUTHWEST ON FRIDAY AS THE SURFACE
HIGH SLIPS EAST...BUT WIND WILL REMAIN LIGHT.
&&
PREV DISCUSSION... /ISSUED 408 AM CDT THU SEP 13 2012/
SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT. A RELATIVELY QUITE
PATTERN IS EXPECTED OVER THE NEXT FEW DAYS. PRECIPITATION WILL EXIT
THE OUTLOOK AREA THIS MORNING MORNING...AND THIS WILL BEGIN THE
RELATIVELY QUITE WEATHER AS HIGH PRESSURE SLIDES INTO THE REGION
FROM THE WEST.
THE LATEST RUNS OF BOTH THE NAM AND RUC SUGGEST PRECIPITATION ENDING
ACROSS THE CWA BY MID TO LATE MORNING. FURTHERMORE...THE HRRR ALSO
DEPICTS DRY CONDITIONS BY MID MORNING...SO WENT AHEAD AND SPLIT THE
12Z TO 18Z BLOCK INTO TWO 3 HOUR GROUPS TO ACCOUNT FOR THE
PRECIPITATION ENDING EARLIER THAN PREVIOUSLY FORECAST THIS
MORNING.
WITH LIGHT WINDS AND SUBSIDENCE EXPECTED BEHIND THE EXITING
STRATUS...THERE WILL BE A CHANCE FOR SOME PATCHY FOG EARLY THIS
MORNING...ESPECIALLY NORTHWESTERN PARTS OF THE CWA IF ENOUGH
CLEARING CAN OCCUR BEFORE DAYTIME HEATING BEGINS. CONFIDENCE IS NOT
HIGH ENOUGH TO GO WITH A PRE-FIRST PERIOD AS MOST SPOTS SHOULD BE
ABOVE 3 MILES OF VISIBILITY BY 12Z. NOT GOING TO INCLUDE THE
MENTIONING OF FOG AT THIS TIME BUT THOUGHT IT WAS WORTH MENTIONING.
GOING TO LEAVE IT IN THE GRIDS THOUGH.
THE BIGGEST FORECAST CHALLENGE FOR THE REST OF THE SHORT TERM WILL
BE TEMPERATURES. TEMPERATURES ON FRIDAY WERE NOTICEABLY DIFFERENT
THAN PREVIOUSLY FORECAST...WITH HIGHS 3 TO 4 DEGREES WARMER IN MOST
LOCATIONS. FRIDAY MORNING LOW TEMPERATURES WERE ALSO 3 TO 4 DEGREES
WARMER IN MOST LOCATIONS. THE THOUGHT BEHIND THESE HIGHER
TEMPERATURES IS MOST LIKELY GUIDANCE KEYING ON HIGHER DEWPOINTS FROM
THE RECENT RAINFALL...MOSTLY CLEAR SKIES...AND ADIABATIC COMPRESSION
FROM THE WESTERLY WIND COMPONENT. THE LATEST RUN OF THE NAM12 ALSO
DEPICTS WARM AIR ADVECTION AT 850MB AS OPPOSED TO PREVIOUS RUNS...SO
WENT AHEAD AND RAISED TEMPERATURES A FEW DEGREES TO ACCOUNT FOR THIS
WARMER SETUP. THIS WAS THE BIGGEST CHANGE DURING THIS PERIOD.
OVERALL...NEAR SEASONABLE TEMPERATURES AND DRY CONDITIONS WILL BE
EXPERIENCED BOTH FRIDAY AND SATURDAY.
LONG TERM...SUNDAY THROUGH WEDNESDAY...A BEAUTIFUL END OF THE
WEEKEND APPEARS TO BE ON TAP FOR THE REGION SUNDAY AS SEASONABLY
WARM TEMPERATURES...LIGHT SOUTHERLY WINDS....AND ONLY A FEW HIGH
CLOUDS ARE EXPECTED AHEAD OF AN APPROACHING FRONTAL BOUNDARY. THIS
FRONTAL BOUNDARY WILL BE STEERED ACROSS THE PLAINS SUNDAY NIGHT
THROUGH MONDAY BY AN UPPER LEVEL SHORTWAVE...WITH A MARKEDLY COOLER
AIRMASS EXPECTED IN ITS WAKE AS 850MB TEMPS AREA FORECAST TO DROP
8-10C BEHINDS THIS FRONT. WHILE THERE WILL ALSO BE A CHANCE FOR A
FEW SHOWERS AND EVEN AN ISOLATED THUNDERSTORM LATE SUNDAY NIGHT
THROUGH MONDAY EVENING...THE BEST UPPER LEVEL FORCING APPEARS TO BE
TO DIRECTED THE NORTHEAST OF THE LOCAL AREA IN BOTH LATEST RUNS OF
THE GFS AND EC...AND DECIDED TO TONE DOWN PRECIP CHANCES ACCORDINGLY
OVER THIS TIME PERIOD AS A DEVELOPING UPPER LEVEL RIDGE ACROSS THE
WESTERN STATES APPEARS TO BE SHIFTING THE FOCUS OF THIS SYSTEM AWAY
FROM THE AREA.
THEREAFTER...A GENERALLY NORTHWESTERLY UPPER LEVEL FLOW PATTERN IS
PROGGED TO KEEP MAIN FOCUS OF WEATHER ACROSS THE CENTER OF THE
COUNTRY THROUGH MID WEEK...WITH SEASONABLY COOL TEMPERATURES
EXPECTED AGAIN ON TUESDAY...WITH A BRIEF WARMING TO NEAR OR ABOVE
CLIMO WEDNESDAY...AHEAD OF THE NEXT APPROACHING COLD FRONT. WHILE
MODELS WERE TRYING TO KEY IN ON SOME SMALL CHANCE POPS WITH THIS
NEXT BOUNDARY WED/WED NIGHT...WITH PERSISTENT UPPER LEVEL RIDGE OVER
THE WEST COAST AND CORRESPONDING FOCUS OF STORM TRACK TO OUR
EAST...NOT TO MENTION VERY LIMITED LOW LEVEL MOISTURE...WENT AHEAD
AND REMOVED SMALL CHANCE POPS FROM THE FORECAST WITH THIS SECOND
FRONT MID WEEK IN COORDINATION WITH SURROUNDING OFFICES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION/UPDATE...HEINLEIN
SHORT TERM...GUERRERO
LONG TERM...ROSSI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
313 PM CDT THU SEP 13 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY
313 PM CDT THU SEP 13 2012
MAIN FORECAST CONCERNS ARE FOG IN RIVER VALLEYS AND FROST POTENTIAL
TONIGHT...THEN TEMPERATURES FRIDAY THROUGH SUNDAY.
LATEST WATER VAPOR SATELLITE IMAGERY SHOWS UPPER LEVEL LOW OVER
SOUTHERN MANITOBA AND SHORTWAVE TROUGH EMBEDDED IN THE
NORTHWESTERLY FLOW OVER CENTRAL NORTH DAKOTA. LATEST 19Z SURFACE
ANALYSIS INDICATING HIGH PRESSURE BUILDING INTO WESTERN IOWA AND
DRIER AIR BEGINNING TO ADVECT INTO WESTERN FORECAST AREA...WITH
DEWPOINTS FALLING INTO THE MIDDLE 20S TO MIDDLE 30S ACROSS SOUTHERN
AND WESTERN MINNESOTA.
THE 13.12Z GFS/NAM ARE IN DECENT AGREEMENT WITH DEVELOPING ZONAL
FLOW ACROSS THE NORTHERN TIER STATES THIS WEEKEND. THE MOST
SIGNIFICANT DIFFERENCE BETWEEN THE DETERMINISTIC MODELS IS THE NAM
SLIGHTLY FARTHER SOUTH WITH SURFACE FRONT SUNDAY THAN THE GFS. THIS
WOULD PUSH THE MOISTURE CONVERGENCE AND LIFT ALONG THE FRONT INTO THE
NORTHERN FORECAST AREA. HOWEVER...FEEL THE NAM IS TOO FAR SOUTH AND
FOLLOW MORE TOWARDS THE GFS DURING THIS TIMEFRAME.
TONIGHT...THE DETERMINISTIC 13.12Z GFS/NAM AND 13.18Z RAP ARE PICKING
UP WEAK WARM AIR ADVECTION AT 700MB OUT AHEAD OF THE SHORTWAVE TROUGH
OVER CENTRAL NORTH DAKOTA AND PRODUCING MOISTURE IN THE 600-800MB
LAYER PER BUFKIT SOUNDINGS. THE MOISTURE IN THIS LAYER THE
DETERMINISTIC MODELS PROG INTO THE FORECAST AREA AFTER 03Z FRIDAY AND
WILL HAVE IMPACTS ON TEMPERATURES AND FOG POTENTIAL. AT THIS TIME...
UNCERTAINTY EXIST ABOUT FOG DEVELOPMENT IN THE MISSISSIPPI RIVER
VALLEY...AS THE 13.12Z DETERMINISTIC MODELS ARE IN AGREEMENT SOME MID
LEVEL CLOUDS WILL DRIFT OVER THE FORECAST AREA BETWEEN 03Z-09Z
TIMEFRAME. FOR NOW...HAVE KEPT PATCHY TO AREAS FOG IN RIVER VALLEYS.
TEMPERATURES WILL BE AFFECTED BY THE SCATTERED TO BROKEN MID LEVEL
DECK CLOUDS ESPECIALLY OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA.
THE 13.12Z DETERMINISTIC MODELS DISSIPATE MOISTURE/MID CLOUD DECK
OVER WESTERN/CENTRAL WISCONSIN AND TEMPERATURES ARE EXPECTED TO FALL
INTO THE MIDDLE 30S OVER PARTS OF CENTRAL WISCONSIN AND PRODUCE
ISOLATED SPOTS OF PATCHY FROST.
SURFACE RIDGE DOMINATES THE FORECAST AREA FRIDAY INTO SATURDAY
PROVIDING DRY WEATHER CONDITIONS. TEMPERATURES ARE EXPECTED TO
MODERATE AND BE SLIGHTLY ABOVE NORMAL BOTH DAYS...AS THE 13.12Z
DETERMINISTIC MODELS ADVECT SOME WARMER AIR INTO THE AREA.
SURFACE RIDGE BUILDS INTO THE OHIO RIVER VALLEY SATURDAY
NIGHT/SUNDAY AND SOUTHERLY WINDS ON THE BACKSIDE OF THE HIGH PRESSURE
SYSTEM AND ALOFT...WILL USHER IN LOW LEVEL MOISTURE FROM THE
SOUTHERN PLAINS STATES NORTHWARD INTO THE FORECAST AREA. THIS IS
EVIDENT IN THE 850MB TO 925MB RELATIVE HUMIDITY FIELDS PER 13.12Z
GFS/NAM. HAVE INCREASE SKY COVER SLIGHTLY SUNDAY.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
313 PM CDT THU SEP 13 2012
MAIN FORECAST CONCERNS THROUGH THE PERIOD ARE PRECIPITATION CHANCES
AND TEMPERATURES. THE 13.12Z GFS/ECMWF/GEM ARE IN ALL PRETTY GOOD
AGREEMENT IN DIGGING UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS AND
THE UPPER GREAT LAKES REGION THROUGH FORECAST PERIOD. BIGGEST
DIFFERENCE BETWEEN THE DETERMINISTIC MODELS IS TIMING OF THE
EMBEDDED SHORTWAVE TROUGHS IN THE NORTHERLY FLOW ALOFT. THIS WILL
HAVE IMPACTS ON TIMING OF PRECIPITATION CHANCES INTO THE FORECAST
AREA THROUGH THE FORECAST PERIOD. THE DETERMINISTIC 13.12Z
GFS/ECMWF/GEM CONTINUE TO SHOW COLDER AIR TO FILTER INTO THE AREA
WITH 850MB TEMPERATURES DROPPING TO AROUND ZERO DEGREES CELSIUS AT
12Z TUESDAY. THE 13.00Z GEFS INDICATE STANDARD ANOMALIES OF MINUS 1
TO MINUS 1.5 OVER THE FORECAST AREA MIDDLE OF NEXT WEEK.
TEMPERATURES WILL BE BELOW NORMAL THROUGH MUCH OF THE FORECAST
PERIOD WITH HIGH TEMPERATURES RISING INTO THE 50S TO 60S.
&&
.AVIATION...THROUGH 18Z FRIDAY
1228 PM CDT THU SEP 13 2012
BIGGEST CONCERN IS LIFR VALLEY FOG AT KLSE OVERNIGHT. QUITE A FEW
POSITIVES FOR LIFR VALLEY FOG INCLUDING LIGHTER WINDS IN THE
0-1KFT LAYER...RECENT SOAKING RAINS...CLOUDS PREVENTING AN THE MIXING
OF BOUNDARY LAYER MOISTURE TODAY AND A LOWER MAX TEMPERATURE
TODAY. THE LAST ITEMS MAKE FOR A SMALLER TEMPERATURE DEWPOINT
SPREAD...FAVORABLE FOR FOG FORMATION OVERNIGHT. THE ONLY NEGATIVE
RIGHT NOW IS AN UPSTREAM SHORTWAVE TROUGH THAT IS MOVING INTO MN
OVERNIGHT AND INTO WI. A FAIRLY CONSISTENT SIGNAL EXISTS IN THE
HIGH-RESOLUTION MODELS THAT THE WARM ADVECTION AHEAD OF THAT
SYSTEM WILL PROVIDE SOME INSTABILITY FOR SOME MID-LEVEL CLOUDS AND
VERY LIGHT RADAR ECHO. THIS WOULD ARRIVE AT KLSE BETWEEN
06-09Z...AND PROVIDE NO RAIN BUT SCT-BKN100 CLOUDS TO LIMIT
COOLING.
CONFIDENCE IS HIGH THAT IF THIS MID-LEVEL CLOUD DOES NOT MOVE OVER
KLSE..AN LIFR FOG EVENT WILL OCCUR FROM 09-14Z. AT THIS TIME...A
MAJORITY OF THE NUMERICAL GUIDANCE DOES GENERATE THIS CLOUD AND
THEREFORE THE KLSE TAF CONTAINS A REDUCTION ONLY TO MVFR IN FOG.
THIS MID-CLOUD FORECAST SHOULD BE RESOLVED VIA LATER TAF ISSUANCES
AND WE WILL BE PRUDENT TO UPDATE THE KLSE TAF AS SOON AS THE PROBABLE
OUTCOME HAS MORE CONFIDENCE.
A VFR PERIOD IS EXPECTED AT KRST AND KLSE FROM FRIDAY AT 15Z THROUGH
SUNDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
313 PM CDT THU SEP 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM.....DTJ
LONG TERM......DTJ
AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1229 PM CDT THU SEP 13 2012
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
307 AM CDT THU SEP 13 2012
MAIN FORECAST CONCERNS ARE ON TIMING THE END OF ONGOING
PRECIPITATION...POTENTIAL FOR FROST AND VALLEY FOG TONIGHT...AND
POSSIBLE FIRE WEATHER CONCERNS FOR SATURDAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO SOUTHWEST CANADA...
TROUGHING FROM SOUTH CENTRAL CANADA INTO NEBRASKA...AND RIDGING
ALONG THE EAST COAST. WITHIN THE UPPER TROUGHING...NOTABLE FEATURES
INCLUDE A SHORTWAVE OVER NORTHWEST IOWA AND AN UPPER LOW OVER
CENTRAL SASKATCHEWAN. THE FORECAST AREA RESIDES IN SOUTHWEST FLOW
AHEAD OF THE NORTHWEST IOWA SHORTWAVE...AS WELL AS IN A RIGHT
ENTRANCE REGION OF A 100-120KT JET AT THE TROPOPAUSE EXTENDING
FROM CENTRAL MINNESOTA INTO NORTHERN ONTARIO. THE FORECAST AREA
ALSO RESIDES IN A LOW TO MID LEVEL FRONTOGENESIS ZONE...WHICH
SHOWS UP IN 700MB PROFILER DATA AS WELL AS IN 850MB TEMPS FROM 00Z
RAOBS (8C AT MPX COMPARED TO 13C AT GRB AND 16C AT DVN). THE
COMBINATION OF ALL THESE FORCING FEATURES RESULTING IN A BAND OF
SHOWERS FROM THE OKLAHOMA AND TEXAS PANHANDLES NORTHEASTWARD TO LA
CROSSE AND INTO EASTERN UPPER MICHIGAN. BACK EDGE OF SHOWERS WAS
NEAR ALBERT LEA AND DODGE CENTER MN. BACK EDGE OF THE CIRRUS CLOUD
COVER WAS QUITE A BIT FARTHER NORTHWEST...THOUGH...NEAR ST CLOUD.
PLENTY OF LOW LEVEL DRY AIR ALSO TO THE NORTHWEST...NOTED BY
SURFACE DEWPOINTS IN THE TEENS AND LOW 20S ACROSS NORTH DAKOTA TO
ALEXANDRIA MN. GOES SOUNDER PRECIPITABLE WATER IMAGERY DEPICTING
VALUES AROUND 0.3 INCHES OVER NORTH DAKOTA...OR ABOUT 50 PERCENT
OF NORMAL.
TODAY AND TONIGHT...AFTER MUCH STRUGGLES THE PAST COUPLE DAYS WITH
THE UPPER LOW IN SASKATCHEWAN...MODELS ARE ALL NOW IN SYNC WITH
BASICALLY WHAT THE OUTLIER 11.00Z NAM SUGGESTED. MODELS DROP THE
UPPER LOW INTO THE MEAN TROUGHING... REACHING NORTHERN MINNESOTA
BY 00Z. THE UPPER LOW THEN RAPIDLY HEADS EAST TO NORTHERN LOWER
MICHIGAN BY 12Z FRIDAY. MEANWHILE...THE NORTHWEST IOWA SHORTWAVE
IS PROGGED TO MOVE NORTHEAST THROUGH THE FORECAST AREA DURING THE
DAY TODAY. THE COMBINATION OF THE UPPER LOW AND IOWA SHORTWAVE WILL
PUSH THE FRONTOGENESIS ZONE AND ITS ASSOCIATED SHOWERS EAST OUT OF
THE FORECAST AREA. TIMING WISE...MOST OF THE AREA SHOULD BE DRY
AFTER 18Z. IN ADDITION...AS THE UPPER LOW APPROACHES...DRIER AIR
AND CLEARING SEEN OFF TO OUR NORTHWEST OVER THE DAKOTAS AND
NORTHWEST MINNESOTA WILL ADVECT IN. PREVIOUSLY THERE WAS CONCERN
ABOUT THE UPPER LOW DROPPING INTO MINNESOTA BRINGING SOME ISOLATED
PRECIPITATION TO THE AREA. HOWEVER...NOW THAT MODELS ARE TRACKING
THE UPPER LOW SO FAR NORTH...AND ITS TIMING DOES NOT COINCIDE WITH
PEAK HEATING...NOT ANTICIPATING ANY PRECIPITATION WITH IT.
THEREFORE...DRY CONDITIONS ARE EXPECTED ONCE THE PRECIPITATION
ASSOCIATED WITH THE FRONTOGENESIS ENDS. IN FACT...INDICATIONS ARE
THAT MUCH OF THE FORECAST AREA WILL BE CLEAR TONIGHT. WITH
PRECIPITABLE WATER VALUES DROPPING TO 0.3-0.4 INCHES AND LIGHT
WINDS ASSOCIATED WITH HIGH PRESSURE OVERHEAD AFTER MIDNIGHT...
TEMPERATURES ARE GOING TO TANK. HAVE LEANED TOWARDS THE COLDER OF
GUIDANCE...DROPPING THE TYPICAL COLD SPOTS IN WISCONSIN TO NEAR
FREEZING WITH MID 30S TO MID 40S ELSEWHERE. PATCHY FROST LOOKS
LIKELY ACROSS TAYLOR...CLARK... JACKSON...MONROE...JUNEAU AND
ADAMS COUNTIES. APPEARS FROST COVERAGE RIGHT NOW SHOULD STAY LOW
ENOUGH TO PRECLUDE THE NEED FOR ANY ADVISORY. WITH RECENT RAINS
AND LATE IN THE DAY CLEARING...VALLEY FOG ALSO LOOKS LIKELY FOR
THE WISCONSIN RIVER VALLEY AND MISSISSIPPI RIVER TRIBUTARIES. THE
MAIN MISSISSIPPI VALLEY HAS A CONCERN WITH THE DRY AIR
IMPACT...GIVEN THAT TEMP/DEWPOINT SPREADS OF AT LEAST 30F ARE
POSSIBLE BY LATE THIS AFTERNOON. LIGHT WINDS EXTENDING UP A FEW
THOUSAND FEET AND RECENT RAIN SHOULD ALLOW GOOD DEWPOINT RECOVERY
THIS EVENING...BUT WHETHER IT IS ENOUGH IS UNCERTAIN. THEREFORE...
HAVE KEPT THE MISSISSIPPI RIVER VALLEY AT PATCHY FOG FOR THE
PRESENT TIME.
FRIDAY THROUGH SATURDAY NIGHT...MODELS SHOW THAT THE RIDGING
CURRENTLY OVER SOUTHWEST CANADA WILL BREAK DOWN...IN RESPONSE TO
TROUGHING OVER THE GULF OF ALASKA PUSHING EAST. AS SUCH...WE SHOULD
SEE THE FLOW OVER THE NORTHERN U.S. TURN MORE ZONAL....ALLOWING SOME
WARMER AIR THAT GETS DOWNSLOPED OFF THE ROCKIES TO PUSH INTO THE
FORECAST AREA. THERE ARE INDICATIONS THAT TOWARDS LATE SATURDAY
NIGHT SOME WEAK RIDGING WILL BUILD OVER THE WESTERN GREAT LAKES...IN
RESPONSE TO THE GULF OF ALASKA TROUGHING STALLING OVER CENTRAL
CANADA. EXPECT A COLD FRONT TO SEPARATE THE TROUGHING/RIDGING
INTERFACE...WHICH BY 12Z SUNDAY WILL EXTEND FROM NORTHWEST ONTARIO
SOUTHWEST INTO CENTRAL SOUTH DAKOTA. PLENTY OF DRY AIR FROM THE
LOW TO UPPER LEVELS OF THE TROPOSPHERE AHEAD OF THE FRONT IS
EXPECTED TO PRODUCE CLEAR SKIES FOR MUCH OF THIS PERIOD. A
TIGHTENING PRESSURE GRADIENT AHEAD OF THE FRONT SHOULD HELP TO
INCREASE THE WINDS OVER THE FORECAST AREA...BEGINNING FRIDAY NIGHT
AND ESPECIALLY FOR SATURDAY AND SATURDAY NIGHT. WITH MORE
WIND...AS WELL AS PRECIPITABLE WATER VALUES PROGGED TO CLIMB TO
AROUND 0.5 INCHES... ANTICIPATE WARMER LOWS FOR FRIDAY NIGHT AND
THUS LITTLE CONCERN FOR FOG OR FROST. 850MB TEMPS OF 8-10C ON
FRIDAY SHOULD ALLOW FOR HIGHS IN THE LOWER 70S. ON SATURDAY...
THOSE 850MB TEMPS CLIMB TO 11-13C AND WITH THE INCREASING
SOUTHWEST WIND...TEMPERATURES SHOULD TOP OUT IN THE MID TO UPPER
70S. A FEW LOCATIONS MAY EVEN REACH 80. MAY HAVE TO WATCH FIRE
WEATHER CONDITIONS FOR SATURDAY. SEE FIRE WEATHER DISCUSSION
BELOW. EVEN WARMER LOWS EXPECTED SATURDAY NIGHT WITH A SOUTHWEST
BREEZE CONTINUING...THOUGH THE DRY AIR LIKELY ALLOWING SOME OF THE
TYPICAL COLD SPOTS TO DROP INTO THE LOW TO MID 40S.
.LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT
307 AM CDT THU SEP 13 2012
13.00Z ECMWF/GFS/UKMET AND GFS ENSEMBLES ARE IN EXCELLENT AGREEMENT
ON A MAJOR PATTERN SHIFT FOR THE LONG TERM PERIOD. THE 13.00Z
CANADIAN HAS THE PATTERN SHIFT TOO...BUT WILL BE DISCOUNTED AS AN
OUTLIER SINCE THE POSITION OF THE UPPER TROUGHING COME 00Z TUESDAY
AND ESPECIALLY BY 00Z WEDNESDAY DOES NOT AGREE WITH THE
AFOREMENTIONED MODELS.
ON SUNDAY...RIDGING REALLY AMPLIFIES OVER FAR WESTERN CANADA. IN
TURN...THIS FORCES A DEEPENING TROUGH DOWNSTREAM...WHICH DIGS DOWN
INTO THE NORTHERN PLAINS SUNDAY NIGHT. THIS TROUGH DIGGING DOWN
SHOULD HELP PUSH EASTWARD THE COLD FRONT THAT WAS OVER SOUTH DAKOTA
12Z SUNDAY. IT APPEARS THE FRONT WILL CROSS THE FORECAST AREA SUNDAY
NIGHT. PRIOR TO THE FRONTAL PASSAGE...SUNDAY SHOULD BE ANOTHER WARM
DAY WITH 850MB TEMPS OF 12-14C AND PLENTY OF SUN. HIGHS ARE LIKELY
TO BE EQUAL TO OR SLIGHTLY HIGHER THAN SATURDAY. ANOTHER
FRONTOGENETIC BAND OF PRECIPITATION LOOKS TO DEVELOP ON THE COOL
SIDE OF THE FRONT. THEREFORE...40-60 PERCENT CHANCES OF PRECIPITATION
EXIST ACROSS THE FORECAST AREA FOR BOTH SUNDAY NIGHT AND MONDAY.
FUTURE SHIFTS MAY BE ABLE TO INCREASE THESE MORE. ADDED A LOW
CHANCE OF THUNDER AS WELL GIVEN MUCAPE FORECASTS OF 300 J/KG OR SO
WITH THE FRONTOGENESIS BAND. THE UPPER TROUGH LOOKS TO DIG INTO
THE AREA FOR MONDAY NIGHT AND TUESDAY. COMBINATION OF COOL
TEMPERATURES ALOFT AND ANY SHORTWAVES MOVING THROUGH THE TROUGH
RESULTS IN THE NEED TO MAINTAIN 20-30 PERCENT CHANCES DURING THIS
TIME FRAME. A BRIEF BREAK IN PRECIPITATION IS ANTICIPATED TUESDAY
NIGHT...THEN MODELS HAVE ANOTHER POTENT SHORTWAVE DROPPING DOWN
INTO THE NORTHERN PLAINS ON WEDNESDAY. SOME WARM ADVECTION AND
DPVA FORCED PRECIPITATION IS POSSIBLE AHEAD OF IT...THOUGH
AVAILABLE MOISTURE IS A QUESTION MARK...THUS CONSENSUS 20 PERCENT
CHANCES ARE WARRANTED.
AS THE UPPER TROUGH DROPS INTO THE AREA ON MONDAY...850MB TEMPS
REALLY TUMBLE. BY 00Z TUESDAY...THEY ARE FORECAST DOWN TO AT LEAST
3-6C AND MAY EVEN FALL A LITTLE MORE...ESPECIALLY AS WE HEAD TO 12Z
TUESDAY. AS A RESULT...BOTH MONDAY AND TUESDAY LOOK CHILLY WITH
HIGHS IN THE 60S MONDAY AND 50S TUESDAY. 850MB TEMPS SHOULD WARM
BACK UP TUESDAY NIGHT INTO WEDNESDAY...PERHAPS PEAKING AS HIGH AS
8-11C PER 13.00Z ECMWF...IN RESPONSE TO THE NEXT POTENT SHORTWAVE
DROPPING THROUGH THE TROUGH. THEREFORE...HIGHS SHOULD CLIMB BACK
INTO THE 60S FOR WEDNESDAY.
FOR THOSE LOOKING FARTHER OUT...IT APPEARS THE MEAN UPPER TROUGHING
WILL STAY IN PLACE AND PERHAPS EVEN AMPLIFY THROUGH THE END OF NEXT
WEEK...PER THE 13.00Z ECMWF/GFS. THIS IS ALSO IN GOOD AGREEMENT WITH
THE 12.00Z CFS WHICH HAS BEEN SHOWING A CONSISTENT SIGNAL OF
BELOW NORMAL TEMPERATURES FOR THE LATTER HALF OF SEPTEMBER OVER
THE CENTRAL AND EASTERN PORTION OF THE U.S.
&&
.AVIATION...THROUGH 18Z FRIDAY
1228 PM CDT THU SEP 13 2012
BIGGEST CONCERN IS LIFR VALLEY FOG AT KLSE OVERNIGHT. QUITE A FEW
POSITIVES FOR LIFR VALLEY FOG INCLUDING LIGHTER WINDS IN THE
0-1KFT LAYER...RECENT SOAKING RAINS...CLOUDS PREVENTING AN THE MIXING
OF BOUNDARY LAYER MOISTURE TODAY AND A LOWER MAX TEMPERATURE
TODAY. THE LAST ITEMS MAKE FOR A SMALLER TEMPERATURE DEWPOINT
SPREAD...FAVORABLE FOR FOG FORMATION OVERNIGHT. THE ONLY NEGATIVE
RIGHT NOW IS AN UPSTREAM SHORTWAVE TROUGH THAT IS MOVING INTO MN
OVERNIGHT AND INTO WI. A FAIRLY CONSISTENT SIGNAL EXISTS IN THE
HIGH-RESOLUTION MODELS THAT THE WARM ADVECTION AHEAD OF THAT
SYSTEM WILL PROVIDE SOME INSTABILITY FOR SOME MID-LEVEL CLOUDS AND
VERY LIGHT RADAR ECHO. THIS WOULD ARRIVE AT KLSE BETWEEN
06-09Z...AND PROVIDE NO RAIN BUT SCT-BKN100 CLOUDS TO LIMIT
COOLING.
CONFIDENCE IS HIGH THAT IF THIS MID-LEVEL CLOUD DOES NOT MOVE OVER
KLSE..AN LIFR FOG EVENT WILL OCCUR FROM 09-14Z. AT THIS TIME...A
MAJORITY OF THE NUMERICAL GUIDANCE DOES GENERATE THIS CLOUD AND
THEREFORE THE KLSE TAF CONTAINS A REDUCTION ONLY TO MVFR IN FOG.
THIS MID-CLOUD FORECAST SHOULD BE RESOLVED VIA LATER TAF ISSUANCES AND WE
WILL BE PRUDENT TO UPDATE THE KLSE TAF AS SOON AS THE PROBABLE
OUTCOME HAS MORE CONFIDENCE.
A VFR PERIOD IS EXPECTED AT KRST AND KLSE FROM FRIDAY AT 15Z THROUGH SUNDAY.
&&
.FIRE WEATHER...FRIDAY AND SATURDAY
307 AM CDT THU SEP 13 2012
ON FRIDAY...HIGH PRESSURE OVERHEAD COMBINED WITH PLENTY OF DRY AIR
WILL RESULT IN RELATIVE HUMIDITY VALUES DROPPING TO AROUND 25
PERCENT ACROSS MUCH OF THE AREA. RECENT RAINS PLUS WINDS LESS THAN
10 MPH SHOULD PRECLUDE ANY FIRE WEATHER CONCERNS...THOUGH THE DRY
AIR AND FULL SUNSHINE WILL HELP TO DRY OUT FUELS.
ON SATURDAY...THE COMBINATION OF SOUTHWEST WINDS INCREASE TO 10 TO
15 MPH WITH HIGHER GUSTS...ALONG WITH PLENTY OF DRY AIR IN THE
ATMOSPHERE ALLOWING FOR GOOD MIXING SHOULD SEND RELATIVE HUMIDITY
VALUES PLUMMETING TO 25 TO 30 PERCENT IN THE AFTERNOON. LOWEST
RELATIVE HUMIDITY VALUES AND HIGHEST WINDS LOOK TO OCCUR WEST OF THE
MISSISSIPPI RIVER. IN ADDITION...HIGH TEMPERATURES ARE EXPECTED TO
TOP OUT IN THE MID TO UPPER 70S. WILL HAVE TO WAIT AND SEE HOW MUCH
THE FUELS DRY OUT OVER THE NEXT TWO DAYS...BUT AT LEAST WEATHER WISE
THERE IS SOME CONCERN FOR INCREASED WILDFIRE POTENTIAL. THE CONCERN
WOULD ONLY INCREASE WITH A LITTLE MORE WIND AND/OR LOWER RELATIVE
HUMIDITY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
307 AM CDT THU SEP 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM.....AJ
LONG TERM......AJ
AVIATION...BAUMGARDT
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1147 AM CDT THU SEP 13 2012
.UPDATE...MAIN CONCERNS/PROBLEMS OF THE DAY IS TIMING THE
BEGINNING/END OF PRECIP AND HIGH TEMPS. REGARDING HIGHS...THEY
WERE LOWERED AND MODIFIED TO TOP OUT IN THE UPPER 50S TO THE LOW
60S...AS WE WILL HAVE MOSTLY CLOUDY SKIES AND PRECIP TO CONTEND
WITH TODAY. CURRENT TEMPERATURE TREND HAS BEEN TOO FAR AHEAD AND
WARM.
RADAR SHOWS A RAGGED BAND OF LIGHT PRECIP STRETCHING SW-NE ACROSS
TWO-THIRDS OF THE WESTERN PORTION OF THE CWA. HOURLY PRECIPITATION
AMOUNTS HAVE BEEN RANGING FROM ONE TO FIVE HUNDREDTHS OF AN INCH
ACROSS SOUTHWEST AND SOUTH CENTRAL WISCONSIN. OVER THE LAST TWO
HOURS...THE BAND HAS DIMINISHED IN INTENSITY AND BECOME RAGGED AS IT
PROGRESSES EAST. RAIN SHOULD BE FAIRLY STEADY OVER ANY GIVEN AREA
THOUGH WITH A DURATION OF TWO TO THREE HOURS. TOTAL AMOUNTS ARE
ANTICIPATED TO BE AROUND A TENTH AT BEST. ALL NUMERICAL MODELS ARE
SHOWING THIS BAND OF PRECIPITATION...SO CONFIDENCE IS HIGH THAT
AREAS WILL BE HIT WITH A FEW HUNDREDTHS AT LEAST. HRRR IN PARTICULAR
SHOWS IT DIMINISHING AS IT MOVES EAST...WHICH DOES COINCIDE WITH
CURRENT THINKING. SHOULD BE OUT OF FAR SOUTHEAST WISCONSIN BETWEEN
6-7 PM THIS EVENING.
&&
.AVIATION/18Z TAFS/...LIGHT RAIN WILL CONTINUE EASTWARD ACROSS
SOUTHERN WISCONSIN THIS AFTERNOON...SLOWLY WINDING DOWN WEST TO
EAST. THE RAIN SHOULD CLEAR THE SOUTHEAST EARLY EVENING...WITH
JUST LINGERING MID AND HIGH LEVEL CLOUDS. SKIES EXPECTED TO CLEAR
FROM THE WEST THROUGH LATE EVENING...REMAINING MOSTLY CLEAR
THROUGH THE NIGHT AND ALSO THROUGH FRIDAY. VFR CONDITIONS THUS
EXPECTED TO PREVAIL THROUGH TOMORROW.
&&
.PREV DISCUSSION... /ISSUED 326 AM CDT THU SEP 13 2012/
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
WILL CONTINUE TO MARCH THE BAND OF RAIN ACROSS THE FORECAST AREA
TODAY...BUT HAVE HAD TO SLOW IT DOWN QUITE A BIT. FRONTOGENESIS
CONTINUES TO BE THE MAIN FORCING MECHANISM...ESPECIALLY IN THE
800-600MB LAYER AND THIS ALSO SHOWS A DIMINISHING TREND THIS
AFTERNOON. IN ADDITION...THE UPPER DIVERGENCE ASSOCIATED WITH THE
RIGHT ENTRANCE OF THE JET WEAKENS SIGNIFICANTLY THIS AFTERNOON.
PRECIP PROBABILITIES REMAIN FAIRLY HIGH...BUT RAINFALL AMOUNTS
WON/T BE VERY BENEFICIAL...REMAINING ON THE LIGHT SIDE.
TEMPS FELL PRETTY HARD IN THE WAKE OF THE COLD FRONT
OVERNIGHT...AND RECOVERY WILL BE DIFFICULT TODAY GIVEN THE CLOUDS
AND RAIN. THERE WILL BE AN EVAPORATIVE COOLING ELEMENT TO THE
RESTRICTED TEMPS DUE TO THE LOW DEWPOINTS THAT ADVECTED IN. WILL
END THE RAIN FROM WEST TO EAST BEGINNING THIS AFTERNOON...CLEARING
IT OUT OF THE SOUTHEAST BY EARLY TO MID EVENING.
HIGH PRESSURE AND VERY LOW DEWPOINTS ARRIVE TONIGHT. COULD SEE
SOME UPPER 30S READINGS FOR LOW TEMPS TONIGHT...ESPECIALLY WEST OF
MADISON AND IN THE VALLEYS. NOT CONCERNED ABOUT ANY FROST DUE TO
THE WARM SOIL TEMPS.
FRIDAY THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
SHORTWAVE TROUGH SHIFTS WELL EAST OF THE AREA FRIDAY...WITH WEST
NORTHWEST WINDS AT 500MB OVER THE REGION THROUGH SATURDAY NIGHT.
AT THE SURFACE...HIGH PRESSURE OVER THE REGION FRIDAY WILL SLIDE
EAST SOUTHEAST THROUGH SATURDAY NIGHT. DRY AIRMASS IN PLACE WILL
BRING QUIET WEATHER TO THE AREA DURING THIS TIME. LIGHT WINDS AND
CLEAR SKIES SHOULD LEAD TO PATCHY FOG IN THE WISCONSIN RIVER
VALLEY.
WEAK WARM AIR ADVECTION IN THE LOW LEVEL OCCURS AS WELL...AS
WINDS SHIFT SOUTH TO SOUTHWEST. 925MB TEMPERATURES CONTINUE TO BE
WARMER ON THE NAM THAN THE GFS/ECMWF DURING THIS TIME. LEANED
TOWARD NAM AND WENT WITH LOWER TO MID 70S FRIDAY...AND MID TO
UPPER 70S SATURDAY. LAKE BREEZE SHOULD COOL THINGS DOWN NEAR LAKE
DURING AFTERNOON HOURS EACH DAY. LOWS IN THE 40S ARE EXPECTED EACH
NIGHT...LOWER 50S CLOSE TO LAKE MICHIGAN.
SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM.
ECMWF/GFS CONTINUE TO SHOW QUIET WEATHER THROUGH SUNDAY...AS AREA
REMAINS BETWEEN HIGH PRESSURE TO THE EAST SOUTHEAST...AND THE COLD
FRONT TO THE NORTHWEST. ANOTHER MILD DAY WITH HIGHS IN THE MID TO
UPPER 70S ARE EXPECTED.
THEY BOTH THEN BRING A STRONG COLD FRONT SOUTHEAST TOWARD THE
AREA SUNDAY NIGHT...THEN THROUGH THE AREA MONDAY...EXITING THE
REGION MONDAY NIGHT. BOTH MODELS SHOWING A DIGGING UPPER LEVEL
TROUGH SLIDING SOUTHEAST TOWARD THE AREA SUNDAY NIGHT...THEN
ACROSS THE AREA MONDAY THROUGH TUESDAY...BEFORE MOVING EAST
TUESDAY NIGHT.
GFS FORECAST SOUNDINGS SHOWING GOOD DEEP MOISTURE PROFILES ACROSS
THE AREA MONDAY WITH THE FRONTAL PASSAGE. KEPT HIGH CHANCE POPS
GOING FOR MONDAY ACROSS THE AREA WITH THIS SYSTEM...WITH LIKELY
POPS IN THE FAR WEST. ADDED SLIGHT CHANCES FOR THUNDER AS WELL
WITH WEAK INSTABILITY IN ADJUSTED GFS FORECAST SOUNDINGS.
TEMPERATURES WILL BE RELATIVELY COOL WITH THE CLOUDS AND
PRECIPITATION.
HIGH PRESSURE RIDGE AXIS SHIFTS ACROSS THE AREA TUESDAY NIGHT AND
WEDNESDAY...WITH WARM AIR ADVECTION KICKING IN WEDNESDAY AHEAD OF
ANOTHER SYSTEM MOVING TOWARD THE AREA. KEPT POPS AND COOL
TEMPERATURES GOING FOR THIS PERIOD AS WELL.
AVIATION/12Z TAFS/...BAND OF RAIN WILL CONTINUE TO MARCH ACROSS
THE AREA TODAY. IT LOOKS LIKE THERE WILL BE ABOUT A 6 TO 7 HOUR
PERIOD OF MVFR CIGS WITH RAIN. VSBYS LOOK TO REMAIN VFR THROUGH
THE TAF PERIOD. THE RAIN SHOULD BEGIN TO EXIT THE MADISON AREA BY
EARLY AFTERNOON...AND EARLY EVENING IN THE SOUTHEAST...INCLUDING
THE MILWAUKEE METRO AREA. CLEARING SHOULD BE RAPID IN THE WAKE OF
THE RAIN WITH HIGH PRESSURE AND LIGHT WINDS TONIGHT.
MARINE...A NORTHERLY WIND WILL BRING WAVES CLOSE TO SMALL CRAFT
ADVISORY LEVELS FROM PORT WASHINGTON SOUTH TO WINTHROP HARBOR
TODAY. BUT WILL HOLD OFF ON ISSUING ONE. SMALL CRAFT SHOULD
EXERCISE CAUTION OUT ON LAKE MICHIGAN.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...ET/DDV
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
FRIDAY THROUGH WEDNESDAY...WOOD