Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 05/03/12
AREA FORECAST DISCUSSION
NWS ALBANY NY
343 PM EDT TUE MAY 1 2012
.SYNOPSIS...
A WEAK DOME OF HIGH PRESSURE WILL MOVE ACROSS THE REGION TONIGHT.
HOWEVER...CHANGES ARE ON THE WAY AS WARMER AIR ATTEMPTS TO BUILD
FROM THE SOUTHERN PORTIONS OF THE COUNTRY. ALONG WITH THAT
CHANGE...THERE WILL A CHANCE FOR SHOWERS AND THUNDERSTORMS FOR THE
SECOND HALF OF THE WEEK.
&&
.NEAR TERM /TONIGHT/...
STRATUS DECK CONTINUES TO PLAQUE THE REGION WITH SOME BREAKS IN
THE OVERCAST ACROSS THE MID HUDSON VALLEY. TEMPERATURES HAVE
STRUGGLED TO GET OUT OF THE 50S FOR MOST OF THE CWA...SOME LOWER
60S NOW BEING OBSERVED ACROSS THE MID HUDSON VALLEY WHERE THOSE
BREAKS IN THE CLOUDS ARE UNDERWAY. HOWEVER...EXPECTATION IS FOR
THE STRATUS DECK TO BECOME RE-ESTABLISHED TONIGHT AS THE
COMBINATION OF A MOIST GROUND AND BOUNDARY LAYER COOLING FOR
CONDENSATION TO OCCUR. IN FACT...SFC DEWPOINT DEPRESSIONS ARE
EXPECTED TO NARROW ALONG WITH APPLICATIONS OF THE CROSS OVER
TECHNIQUE AND LOWERING THE MRI IN THE LOWEST 100MB /PER BUFKIT/ TO
RESULT IN PATCHY/AREAS OF FOG.
MORE OF AN INTEREST IS THE WELL DEFINED MCV TRACKING NORTHEAST
ACROSS IL/IN. NCEP MODEL SUITE NOT PERFORMING TOO WELL WITH THIS
FEATURE AS WE REFERRED TO THE NAM ARW CORE AND HOURLY RAPID REFRESH
/REPLACED THE RUC THIS MORNING/. THE ANALYSIS OF THESE MODELS
SUGGESTS THIS MCV SHOULD WEAKEN AS IT APPROACHES THE ANTICYCLONIC
FLOW ACROSS PA/NY. HOWEVER...IT MAY SURVIVE JUST ENOUGH TO WARRANT
THE CHANCE OF POPS SOUTH OF I90 OVERNIGHT. IN ADDITION...THE
THERMAL WIND FORECASTS FROM 850-300MB SUGGEST A MORE EASTWARD
PROGRESSION TO FURTHER SUPPORT THE CHANCE POPS. OVERNIGHT LOWS
WILL DROP BACK MAINLY INTO THE 40S CWA-WIDE.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
A VERY CHALLENGING FORECAST PERIOD WITH LOW CONFIDENCE APPROACH.
CONVECTIVE UPSTREAM TRENDS WILL ULTIMATELY DICTATE THE SYNOPTIC
AND MESOSCALE INFLUENCES AS SPRING ATTEMPTS TO MAKE A STRONG PUSH
INTO THE REGION.
WHAT WE CAN DECIPHER FROM THE NCEP MODEL SUITE AND INTERNATIONAL
GUIDANCE ARE A TREND TOWARD INCREASING HEIGHTS WITH WARMER
TEMPERATURES AND INCREASING AMOUNTS OF MOISTURE. THE CHANCE FOR
SHOWERS WILL EXPAND ACROSS THE REGION WEDNESDAY AS THE NEXT SURGE
OF WARM ADVECTION AND THETA-E ADVECTION APPROACH. MID LEVEL
INSTABILITY REMAINS RATHER POSITIVE /SHOWALTER VALUES INTO THE
SINGLE DIGIT TERRITORY/ TO WITHHOLD THE MENTION OF THUNDER AT THIS
TIME. HOWEVER...THAT IS EXPECTED TO GRADUALLY CHANGE WEDNESDAY
NIGHT INTO THURSDAY NIGHT WHERE WE WILL INTRODUCE THE CHANCE FOR
THUNDERSTORMS.
MOS NUMBERS DO SUPPORT THE INCREASING THERMAL PROFILES BUT CLOUD
COVER REMAINS A CHALLENGE. AT THIS POINT...WE WILL CONTINUE TO
FAVOR ON THE COOLER SIDE OF THE GUIDANCE ENVELOPE.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
THE EARLY PORTION OF THE LONG TERM FORECAST IS UNCERTAIN WITH
WIDE POSSIBLE RANGES IN TEMPS AND POPS. DESPITE BUILDING HEIGHTS
ALOFT INTO FRIDAY...THE WEATHER AT THE SURFACE LOOKS RATHER
NEBULOUS. LATEST GUIDANCE TRENDS FROM THE NAM AND GGEM INDICATE A
POSSIBLE NEARLY STATIONARY FRONTAL BOUNDARY DRAPED OVER THE AREA
WITH WEAK WAVES OF LOW PRESSURE MOVING ALONG THE BOUNDARY. THIS
WOULD RESULT IN A COOLER AND CLOUDIER FORECAST FOR FRIDAY.
HOWEVER...THE GFS CONTINUES TO INDICATE OUR REGION WILL BE IN A
WARM SECTOR AHEAD OF A PRE-FRONTAL TROUGH AND COLD FRONT ATTACHED
TO A STRONGER LOW DROPPING SOUTHEASTWARD THROUGH QUEBEC. THIS
SOLUTION WOULD IMPLY MUCH WARMER TEMPS...MORE IN THE WAY OF
SUNSHINE AND ALSO BETTER CHANCES FOR POTENTIALLY STRONG
CONVECTION. BASED ON THE GFS BEING AN OUTLIER AT THIS POINT...WILL
SIDE WITH THE NAM/GGEM AND ECMWF SOLUTION WITH A COOLER AND
CLOUDIER DAY FOR FRIDAY. STILL RELATIVE TO NORMAL IT WILL BE
WARM...BUT WILL FORECAST TEMPS A GOOD 10 DEGREES COOLER THAN THE
GFS MEX GUIDANCE. THIS COULD END UP CHANGING AS THE WEEK
PROGRESSES.
WHICH EVER TYPE OF SYSTEM AFFECTS THE REGION ON FRIDAY...THERE IS AT
LEAST LOOSE CONSENSUS FOR A NORTHERN STREAM TROUGH TO DIG
SOUTHWARD INTO EASTERN CANADA FRIDAY NIGHT INTO SATURDAY...WHICH
WOULD PUSH THROUGH EITHER THE WEAK WAVE/STATIONARY FRONT OR A
STRONGER CYCLONE. WILL MENTION CHANCE POPS FOR FRIDAY NIGHT INTO
SATURDAY WITH TEMPS STILL REMAINING WARM. DRYING APPEARS POSSIBLE
FOR LATE SATURDAY NIGHT INTO SUNDAY...BUT A LOT DEPENDS ON HOW THE
PATTERN EVOLVES PRIOR TO THE WEEKEND.
WILL MENTION DRY WEATHER AND NEAR NORMAL TEMPS THROUGH EARLY NEXT
WEEK WITH A DRY NORTHERLY FLOW OVER THE AREA DEPICTED BY MOST OF THE
MEDIUM RANGE GUIDANCE.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
MVFR-IFR OVC WAS HANGING TOUGH WITH NO BIG SIGN OF IMPROVEMENT. A
WARM FRONT LIFTING THROUGH PENNSYLVANIA WILL LIKELY STAY WELL WEST
OF THE AIRPORTS THROUGH WEDNESDAY MORNING...RESULTING IN LIGHT
SURFACE WINDS UNDER 7 KNOTS...AND CONTINUED MVFR OVC...WITH SOME
MVFR FOG TOWARD MORNING AS RATHER MOIST DEW POINTS ADVECT IN OFF
THE OCEAN WITH THE FLOW BEING LIGHT SOUTHERLY. WINDS UP TO 2000
FEET WILL BE MAINLY UNDER 15 KNOTS.
.OUTLOOK...
.WED AFTN-THU...MAINLY VFR...CHC -SHRA.
.THU NIGHT-SAT ...MAINLY VFR. CHC -SHRA OR -TSRA.
&&
.FIRE WEATHER...
MINIMAL FIRE WEATHER CONCERNS AS PRECEDING RAINFALL WAS BENEFICIAL
FOR THE REGION. AS THE COMBINATION OF INCREASING MOISTURE AND
COMPETING CLOUD COVER WILL MAKE FOR ELEVATED RELATIVE HUMIDITIES
AND MINIMAL VALUES ON THE HAINES INDEX FOR THE BALANCE OF THE
WEEK.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE EXPECTED THIS WEEK. WHILE CONFIDENCE IN THE
OVERALL EXPECTATIONS OF CONVECTIVE ACTIVITY ARE LOW...WITH LAKE AND
RIVER LEVELS REMAINING QUITE LOW...QPFS ARE EXPECTED TO REMAIN AT
OR BELOW 1 INCH PER THE BASIN AVERAGE.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.CLIMATE...
ALBANY NY:
APRIL AVERAGE TEMPERATURE: 48.1 DEGREES (+0.3 DEGREES)
PRECIPITATION:
APRIL 2012: 2.97 INCHES (-0.20 INCHES)
SINCE MAR 1: 4.51 INCHES (-1.87 INCHES)
SINCE JAN 1: 7.77 INCHES (-3.40 INCHES)
GLENS FALLS NY:
APRIL AVERAGE TEMPERATURE: 45.2 DEGREES (+0.7 DEGREES)
PRECIPITATION:
APRIL 2012: 2.69 INCHES (-0.31 INCHES)
SINCE MAR 1: 3.92 INCHES (-2.02 INCHES)
SINCE JAN 1: 6.86 INCHES (-4.02 INCHES)
POUGHKEEPSIE NY:
APRIL AVERAGE TEMPERATURE: 50.1 DEGREES (+1.4 DEGREES)
PRECIPITATION:
APRIL 2012: 2.06 INCHES (-1.72 INCHES)
SINCE MAR 1: 3.25 INCHES (-4.10 INCHES)
SINCE JAN 1: 6.86 INCHES (-6.23 INCHES)
BENNINGTON VT:
APRIL AVERAGE TEMPERATURE: 45.6 DEGREES (+0.1 DEGREES)
PRECIPITATION:
APRIL 2012: 2.18 INCHES (-1.09 INCHES)
SINCE MAR 1: 3.76 INCHES (-2.66 INCHES)
SINCE JAN 1: 6.26 INCHES (-5.15 INCHES)
PITTSFIELD MA:
APRIL AVERAGE TEMPERATURE: 45.7 DEGREES (+1.5 DEGREES)
PRECIPITATION:
APRIL 2012: 1.83 INCHES (-2.03 INCHES)
SINCE MAR 1: 2.97 INCHES (-4.26 INCHES)
SINCE JAN 1: 7.18 INCHES (-5.65 INCHES)
FOR MORE GO TO OUR CLIMATE PAGE AT:
WWW.NWS.NOAA.GOV/CLIMATE/LOCAL_DATA.PHP?WFO=ALY
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...JPV
AVIATION...ELH
FIRE WEATHER...BGM
HYDROLOGY...BGM
CLIMATE...IAA
FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
145 PM EDT TUE MAY 1 2012
.SYNOPSIS...
18Z WATER VAPOR AND H4 RUC ANALYSIS SHOWS AN UNAMPLIFIED UPPER
LEVEL PATTERN ACROSS THE CONUS...WITH A NORTHERN STREAM FLOW IN A
MORE-OR-LESS ZONAL CONFIGURATION FROM WEST TO EAST. THE MOST
SIGNIFICANT "KINK" IN THE FLOW IS ASSOCIATED WITH A SHORTWAVE
DIGGING THROUGH THE INTER-MOUNTAIN WEST. THIS ENERGY WILL EJECT
EASTWARD TOWARD THE HIGH PLAINS/UPPER MS VALLEY THIS EVENING
BRINGING THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS. CLOSER TO
HOME...THE UPPER LEVEL DISTURBANCE WHICH HAS BEEN PARKED OVER
SOUTHERN FL/BAHAMAS THE PAST SEVERAL DAYS IS FINALLY WEAKENING AND
TRANSLATING EASTWARD. IN ITS WAKE...WEAK UPPER LEVEL RIDGING IS
TRYING TO BUILD OVER THE PENINSULA. 12Z KTBW SOUNDING PROFILE A
WETTER THAN NORMAL PROFILE WITH A PW VALUE OVER 1.5". DUE TO THE
EXTRA MOISTURE IN THE COLUMN...CAN NOT RULE OUT A FEW SHOWERS LATE
AFTERNOON/EARLY EVENING UP INTO THE TAMPA BAY AREA...HOWEVER THE
SYNOPTIC FLOW SHOULD PREVENT THE DEVELOPMENT OF THE WEST COAST
SEA-BREEZE. THIS LACK OF LOW LEVEL FOCUS AND FADING SYNOPTIC SUPPORT
ALOFT WILL HELP TO KEEP RAIN CHANCES ON THE LOW SIDE. MORE FAVORED
AREAS FOR SHOWERS THE REST OF THE DAYLIGHT HOURS WILL BE DOWN TOWARD
THE FORT MYERS REGION WHERE COLUMN MOISTURE IS EVEN HIGHER.
AT THE SURFACE...FORECAST AREA RESIDES BETWEEN HIGH PRESSURE OFF THE
GEORGIA COAST...AND A WEAK AREA OF LOW PRESSURE MIGRATING WESTWARD
ACROSS THE SOUTH-CENTRAL GULF OF MEXICO. GRADIENT IS STILL RATHER
TIGHT BETWEEN THESE 2 FEATURES KEEPING CONDITIONS ON THE BREEZY
SIDE...ESPECIALLY OVER CENTRAL AND SOUTHERN PORTIONS OF THE FORECAST
AREA. SMALL CRAFT ADVISORY WILL REMAIN UP UNTIL 5 PM EDT ACROSS THE
MARINE AREA FROM ENGLEWOOD TO TARPON SPRINGS.
&&
.SHORT TERM (TONIGHT THROUGH THURSDAY)...
TONIGHT...A FEW EVENING SHOWERS ALONG/NEAR THE COAST FROM TAMPA
SOUTHWARD WILL PUSH OFFSHORE DURING THE EVENING HOURS LEAVING A
GENERALLY DRY FORECAST FOR OUR LAND ZONES DURING MUCH OF THE
OVERNIGHT. TEMPERATURES WILL THE SIMILAR TO PAST NIGHTS WITH LOWS BY
SUNRISE RANGING FROM THE MIDDLE/UPPER 60S INLAND AND NORTH TO THE
LOWER 70S COASTAL AND SOUTH.
WEDNESDAY...
FORECAST AREA WILL FIND ITSELF UNDER STACKED RIDGING. A WEAKER
EASTERLY FLOW WILL PERSIST ON THE SOUTH SIDE OF THE SUBTROPICAL
RIDGE AXIS. GFS/NAM/ECMWF ALL SHOW THE UPPER RIDGE BECOMING A BIT
MORE DOMINANT OVERHEAD AND ALLOWING A DRIER COLUMN TO DEVELOP. THIS
PATTERN WILL LIKELY ALLOW FEEBLE SEA-BREEZE CIRCULATIONS TO DEVELOP
BUT HOLD THESE FEATURES AT THE SHORELINE. BEST RESIDUAL DEEP LAYER
MOISTURE WILL BE CLOSER TO THE COAST IN PROXIMITY TO THE SEA-BREEZE
FOCUS AND THEREFORE CAN`T RULE OUT A FEW ISOLATED SHOWERS...HOWEVER
ONLY GOING WITH A SLIGHT CHANCE 20% POP...AND MOST LOCATIONS WILL
REMAIN RAIN FREE. THE DEEP LAYER SUPPRESSION UNDER THE RIDGE AND
LACK OF CONVECTION SHOULD ALLOW TEMPERATURES TO GET QUITE WARM.
CURRENT GRIDS SHOWING HIGH TEMPERATURES WITHIN A DEGREE OR 2 OF 90
BY MID AFTERNOON WITH LOWER/MID 80S AT THE BEACHES.
THURSDAY...OVERALL SYNOPTIC PATTERN WILL BE SIMILAR TO WEDNESDAY.
PRESSURE GRADIENT WILL RELAX SOMEWHAT AND THE HI-RES GUIDANCE
MEMBERS ARE RESPONDING BY PRODUCING WELL-DEFINED SEA-BREEZE
CIRCULATIONS ALONG THE COAST IN THE AFTERNOON. THE LOW LEVEL FOCUS
ASSOCIATED WITH THESE SEA-BREEZES WILL BE MORE PRONOUNCED...BUT AT
THE SAME TIME...THE OVERALL COLUMN WILL HAVE FURTHER DRIED OUT. IN
FACT...GFS IS SHOWING MID-LEVEL THETAE VALUES OF 317-320K...WHICH
RESEARCH HAS SHOWN TO BE RATHER HOSTILE TO THE DEVELOPMENT OF DEEP
CONVECTION. WITH THIS IN MIND WILL KEEP THE RAIN CHANCES QUITE LOW
(10-20%). TEMPERATURES WILL AGAIN BE QUITE HOT WITH HIGHS AROUND 90
AWAY FROM THE IMMEDIATE COAST.
&&
.LONG TERM (FRIDAY THROUGH MONDAY)...
THE GLOBAL MODELS ARE SIMILAR TO PREVIOUS RUNS OVER THE LAST DAY
OR SO. AN UPPER LEVEL RIDGE OVER THE SE U.S AND A SHORT WAVE TROUGH
SOMEWHERE OVER THE GULF OR GULF COASTAL REGION SLOWLY SHIFTS WEST
DURING THE PERIOD AS AN UPPER TROUGH MOVES INTO WESTERN ATLANTIC
WATERS...OFF THE EAST U.S. COAST. MEANWHILE AT THE SURFACE...A RIDGE
OF HIGH PRESSURE FROM THE OPEN ATLANTIC...ACROSS GA/FL...TO THE
CENTRAL GULF COAST WILL INITIALLY DRIFT WESTWARD. THEN DURING THE
WEEKEND A WEAK FRONTAL BOUNDARY SAGS IN ACROSS THE GULF COAST AND
SE STATES...PUSHING THE RIDGE AXIS SOUTH.
SOME DIFFERENCES IN THE MODEL SOLUTIONS CONTINUE WITH RESPECT TO
LOCATION...TIMING...AND MOISTURE. PREFER TO MAINTAIN THE CURRENT
TREND IN THE FORECAST. PARTLY CLOUDY WITH A SLIGHT CHANCE OF DAYTIME
THUNDERSTORMS...MAINLY IN THE AFTERNOONS. TEMPERATURES WILL BE NEAR
OR JUST ABOVE NORMAL...BY PERHAPS A COUPLE OF DEGREES AT TIMES. AS
THE HIGH MOVES WEST AND THEN SOUTH THE GRADIENT WILL RELAX AND ALLOW
SEA BREEZE CIRCULATIONS FOR THE AFTERNOONS.
&&
.AVIATION...
PREDOMINANTLY VFR WITH SOME SHRA WITH BRIEF MVFR POSSIBLE AT
PGD...FMY AND RSW. GUSTY WINDS DIMINISH TO 8 TO 10 KNOTS OVERNIGHT
THEN INCREASE AGAIN AFTER SUNRISE WEDNESDAY.
&&
.MARINE...
WINDS AND SEAS WILL DROP BELOW ADVISORY LEVELS IN THE NEXT FEW
HOURS...ALTHOUGH PERIODS OF CAUTIONARY LEVEL WINDS WILL REMAIN
POSSIBLE INTO WEDNESDAY MORNING BEFORE SUBSIDING FOR THE AFTERNOON.
ANOTHER EASTERLY SURGE WILL BE POSSIBLE TO NEAR CAUTIONARY LEVELS
WEDNESDAY NIGHT. A WEAKENING GRADIENT WILL THEN DROP WINDS BELOW
HEADLINE CRITERIA FOR THE END OF THE WEEK.
&&
.FIRE WEATHER...
EASTERLY FLOW WILL CONTINUE TO PROVIDE LOW LEVEL ATLANTIC MOISTURE
INTO THE MIDDLE OF THE WEEK. RELATIVE HUMIDITY VALUES ARE EXPECTED
TO REMAIN ABOVE 35% ON WEDNESDAY. A FEW SPOTS BY BRIEFLY DROP TO
NEAR CRITICAL RELATIVE HUMIDITY LEVELS THURSDAY AND FRIDAY
AFTERNOONS AWAY FROM THE COAST...HOWEVER RED FLAG CRITERIA ARE NOT
ANTICIPATED TO BE MET.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 70 89 70 88 / 15 20 5 15
FMY 69 88 69 87 / 20 20 10 15
GIF 68 90 66 90 / 5 10 5 10
SRQ 70 87 70 85 / 20 20 10 15
BKV 67 90 66 89 / 15 20 5 10
SPG 71 87 71 86 / 15 20 10 15
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR
BONITA BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
AVIATION/FIRE WEATHER...JILLSON
LONG TERM...RUDE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1004 PM CDT WED MAY 2 2012
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE....
HAVE MADE SOME SIGNIFICANT ADJUSTMENTS TO POP/WX GRIDS INTO THE
OVERNIGHT HOURS BASED ON ANALYSIS/CONVECTIVE TRENDS UPSTREAM.
WARM FRONT WHICH LIFTED NORTH OF THE FORECAST AREA EARLIER THIS
MORNING HAS BECOME SOMEWHAT ILL-DEFINED ACROSS WISCONSIN AND LOWER
MICHIGAN THIS EVENING...WHILE A SECONDARY TROUGH/WARM FRONT WAS
NOTED FROM NORTHERN MISSOURI INTO CENTRAL IL/IND ENHANCED FROM
COMBINATION OF RETREATING CONVECTIVE OUTFLOW FROM MORNING MCS AND
DIFFERENTIAL HEATING FROM CLOUD COVER EARLIER IN THE DAY. THIS AREA
HAD BECOME RELATIVELY CLOUD-FREE LATE THIS AFTERNOON IN THE WAKE OF
THE SHORT-WAVE TROUGH AXIS WHICH HAS MOVED EAST OF THE AREA PER
WATER VAPOR IMAGERY AND PROFILER WINDS AT WOLCOTT IN. WHILE AIR MASS
IS WARM AND RATHER HUMID...WITH TEMPS STILL IN MID 70S AND DEW
POINTS IN THE MID-UPPER 60S ACROSS SOUTHERN CWA...00Z RAOBS FROM DVN
AND ILX DEPICT STRONG CAPPING INVERSION EXISTS FOR SFC/NEAR SFC
BASED CONVECTION. IN ADDITION...AIR MASS TO THE WEST ACROSS IOWA HAS
REMAINED STABILIZED WITH EXTENSIVE STRATUS DECK THROUGH THE
AFTERNOON AND HAS PREVENTED NEAR SFC BASED CONVECTION FROM
DEVELOPING SAVE FAR SOUTHERN MN/EASTERN NEBRASKA AREAS FARTHER NORTH
AND WEST.
CONVECTION-ALLOWING GUIDANCE INCLUDING WRF-NMM AND HRRR/RAP HAVE
BEEN INDICATING SIGNIFICANT CONVECTIVE DEVELOPMENT ACROSS EASTERN
IOWA INTO SOUTHWEST WISCONSIN DURING THE AFTERNOON AND EVENING
HOURS...BUT BASED ON THERMODYNAMIC PROFILES AND PRE-SUNSET VIS
SATELLITE TRENDS...EARLIER RUNS APPEAR TO HAVE OVER-FORECAST EXTENT
OF DEVELOPMENT. SOME FACTORS DO SUPPORT THE POTENTIAL FOR INCREASING
SHRA/TSRA THREAT THIS EVENING...MAINLY WITH BETTER MOIST ASCENT
DEVELOPING ABOVE STABLE BOUNDARY LAYER AS H9-H8 LOW LEVEL JET
INCREASES TO 35-40 KT AND MID-LEVEL SPEED MAX APPROACHES FROM THE
SOUTHWEST WITHIN AND AREA OF VERY STEEP MID-LEVEL LAPSE RATES WITH
EML NOTED IN OAX/DVN SOUNDINGS. AN ISOLATED AREA OF SHOWERS/WEAK
TSRA HAVE DEVELOPED ALONG A CONVERGENCE ZONE ACROSS FAR EASTERN IA
FROM NEAR MUSCATINE TO JUST WEST OF SAVANNA IL...LIKELY A
REPRESENTATION OF WHAT THE WRF-NMM AND HRRR/RAP WERE TRYING TO
DEPICT BUT ON A MORE LIMITED SCALE. TREND FROM THESE MODELS WOULD
SUGGEST THIS ACTIVITY WILL LIKELY FOCUS MORE ACROSS OUR FAR
NORTHWEST/NORTHERN CWA INTO THE OVERNIGHT HOURS...AND PERHAPS MORE
SO OVER SOUTHERN WI WHERE BETTER DEEP MOIST CONVERGENCE IS NOTED IN
ASSOCIATION WITH SYNOPTIC H9-H8 WARM FRONT. BASED ON ALL OF THIS...
HAVE GENERALLY LOWERED/REMOVED POPS ACROSS THE SOUTHERN CWA
OVERNIGHT. THE RECENT HRRR RUNS WOULD EVEN SUGGEST WE MAY BE DRY
ACROSS THE NORTH EXCEPT FOR RIGHT ALONG THE WI/IL LINE AFTER
MIDNIGHT...THOUGH MY CONFIDENCE IS NOT HIGH ENOUGH TO PULL POPS WITH
UNCERTAIN EVOLUTION OF CONVECTION CURRENTLY FARTHER UPSTREAM. THUS
HAVE GENERALLY LEFT HIGHER POPS GENERALLY NORTH OF I-88 ACROSS
NORTHERN IL...WITH FAR SOUTHERN COUNTIES DRY. HRRR ALSO INDICATES
MCS DEVELOPMENT ACROSS NEBRASKA...WHERE KS/NEBR ACTIVITY IS
CURRENTLY JUST GETTING GOING. LATEST GUIDANCE INDICATES THIS WOULD
NOT ARRIVE UNTIL AFTER 12Z WEDNESDAY IN DECAYING FORM.
RATZER
//PREV DISCUSSION...
329 PM CDT
MAIN FORECAST CHALLENGES REVOLVE AROUND SHOWER/THUNDERSTORM
CHANCES OVER THE NEXT SEVERAL DAYS WITH THE SEVERE POTENTIAL
REMAINING FOR TONIGHT AS WELL AS THURSDAY NIGHT...WITH HIGH
TEMPERATURES BEING DICTATED BY REMNANT PRECIP/CLOUD COVER THROUGH
EACH DAY.
LATEST RADAR IMAGERY DEPICTING AREA OF SHOWERS AND THUNDERSTORMS
WHICH SLOWLY PROGRESSED THROUGH PORTIONS OF THE CWA...CONTINUING
TO DIMINISH THIS AFTERNOON WITH MOST AREAS CURRENTLY DRY. EXPECT
THESE RELATIVELY DRY CONDITIONS TO REMAIN FOR A PORTION OF THIS
AFTERNOON INTO EARLY EVENING...OUTSIDE OF SOME ISOLATED/BRIEF
SHOWERS AND THUNDERSTORMS POSSIBLY DEVELOPING ALONG LINGERING
OUTFLOW BOUNDARIES WHICH SEVERAL ARE CURRENTLY SITUATED OVER THE
CWA. ANY SHOWERS/THUNDERSTORMS WHICH DO DEVELOP THIS AFTERNOON
SHOULD NOT BECOME SEVERE AS INSTABILITY IS STILL LACKING DUE TO A
RECOVERING ENVIRONMENT AND STRONGER WESTERLIES REMAINING TO THE
NORTHWEST.
STRONG SOUTHERLY FLOW OUT AHEAD OF A TROUGH OF LOW PRESSURE WELL
TO THE WEST OVER THE CENTRAL PLAINS WILL HELP FOR THE ENVIRONMENT
OVER THE CWA TO TO SLIGHTLY RECOVER THIS EVENING THROUGH EARLY
THURSDAY MORNING BRINGING LOW TO MID 60S DEWPOINT AIR BACK NORTH
ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS SHOULD HELP
TO INCREASE OVERALL INSTABILITY OVER THE CWA THIS EVENING WHICH
COULD PROVIDE A SETUP FOR ANOTHER ROUND OF THUNDERSTORMS TO RACE
ACROSS THE CWA. MODEL GUIDANCE CONTINUES TO BE ALL OVER THE PLACE
IN REGARDS TO ENVIRONMENTAL DETAILS DUE TO MESOCALE FEATURES WHICH
CONTINUE TO DISRUPT THE LARGE SCALE PATTERN. THIS IS TRANSLATING
TO A LACK OF CONFIDENCE IN MODEL GENERATED PRECIP IN THE NEAR TERM
AS WELL AS FOR THE NEXT SEVERAL DAYS. DESPITE THIS LACK OF
CONFIDENCE IN NUMERICAL GUIDANCE...CAN STILL MAKE OUT SOME OF AREA
FOCUS FOR THUNDERSTORM DEVELOPMENT. ENVIRONMENT SHOULD CONTINUE TO
RECOVER ACROSS THE ENTIRE REGION FROM THE CENTRAL PLAINS BACK EAST
TO THE GREAT LAKES REGION WITH DEEP MOISTURE BACK ON THE RISE.
MAIN INSTABILITY AXIS IS SITUATED FROM WESTERN IOWA EAST INTO
SOUTHERN WISCONSIN...WITH INSTABILITY ANTICIPATED TO CONTINUE TO
INCREASE OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THE EXTENT OF THIS INCREASE OVER THE CWA IS STILL IN
QUESTION...WHICH WILL PLAY A FACTOR IN THUNDERSTORM INTENSITY
TONIGHT. A SUBTLE MID LEVEL IMPULSE CURRENTLY OBSERVED EJECTING
ACROSS THE CENTRAL PLAINS COINCIDING WITH AN INCREASING LLJ SHOULD
INTERACT WITH A FRONTAL BOUNDARY OVER THE CENTRAL PLAINS LATER
THIS EVENING AND HELP FOR THE DEVELOPMENT OF THUNDERSTORMS ACROSS
IOWA. INSTABILITY SHOULD BE MORE THAN ENOUGH TO GET ROBUST
DEVELOPMENT WITH STEERING FLOW/LOW LEVEL SHEAR HELPING TO SHIFT
THIS THUNDERSTORM DEVELOPMENT EAST. A GROWING COMPLEX SHOULD WORK
ITS WAY EAST MAINLY AFFECTING THE NORTHERN HALF OF THE CWA LATER
TONIGHT INTO EARLY THURSDAY MORNING. OVERALL INSTABILITY IS STILL
IN QUESTION ACROSS THE CWA...BUT WITH DEEP MOISTURE NOT. IF
INSTABILITY INCREASES...A HAIL AND WIND THREAT WILL BE POSSIBLE
TONIGHT. IF NOT...AM STILL CONCERNED ABOUT THE POTENTIAL FOR VERY
RAIN EFFICIENT THUNDERSTORMS AS A VERY WARM AND JUICY AIRMASS WILL
BE IN PLACE. WITH ANY MCS PASSAGE TONIGHT...COULD ENVISION FURTHER
UPSCALE DEVELOPMENT AS A STRONG LLJ INTERACTS WITH ANY LINGERING
BOUNDARIES. THIS COULD PROVIDE A SETUP FOR TRAINING OF
THUNDERSTORMS AND HEAVY RAINFALL INTO THURSDAY MORNING.
ADVECTION OF A MUCH WARMER AIRMASS WILL CONTINUE ON THURSDAY WITH
WELL ABOVE NORMAL TEMPERATURES FORECAST. HAVE MAINTAINED MID AND
UPPER 80S FOR THE SOUTHERN HALF OF THE CWA BUT HAVE LOWERED TEMPS
TO AROUND 80 FOR THE NORTHERN HALF DUE TO POSSIBLE LINGERING
CONVECTION AND CLOUD COVER THURSDAY MORNING. ONGOING CONVECTION
DURING THE DAY THURSDAY WILL DEFINITELY BE KEY WITH FURTHER
DEVELOPMENT FOR THE REMAINDER OF THURSDAY INTO FRIDAY
MORNING...WHICH ONCE AGAIN SEEMS PROBABLE. ADVECTION OF A WARM AND
VERY MOIST AIR WILL CONTINUE AIDING IN INSTABILITY WITH THE SETUP
WHICH IS POSSIBLE TONIGHT LIKELY OCCURRING OVER NORTHERN ILLINOIS
ON THURSDAY. THIS WILL BRING ANOTHER ROUND OF THUNDERSTORMS WHICH
WILL BE CAPABLE OF PRODUCING LARGE HAIL/DAMAGING WINDS AND HAIL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* THUNDERSTORM POTENTIAL TONIGHT.
KJB
//DISCUSSION...UPDATED 02Z...
IN SPITE OF THE CAP NOTED IN THE PREVIOUS DISCUSSION RAPID
MOISTENING WITHIN A WARM AIR ADVECTION REGIME HAS LEAD TO THE
DEVELOPMENT OF A CLUSTER OF THUNDERSTORMS ACROSS EAST CENTRAL IOWA
AND PORTIONS OF FAR NORTHWESTERN ILLINOIS. IT APPEARS THE MAIN
THREAT FOR CONVECTION WILL REMAIN ACROSS NORTHWESTERN ILLINOIS AND
INTO WISCONSIN TONIGHT. SOME STORMS MAY GET IN THE VICINITY OF
KRFD AFTER 04 UTC. HOWEVER...THE DIRECTION OF MOVEMENT SHOULD KEEP
A MAJORITY OF THIS ACTIVITY TO THE WEST AND NORTH OF KRFD.
//DISCUSSION...UPDATED 00Z...
THE MAIN CONCERNS DURING THE PERIOD WILL BE TRYING TO PIN DOWN THE
BEST POTENTIAL FOR CONVECTION.
UNFORTUNATELY UNCERTAINTY ON THE OVERALL CONVECTIVE THREAT IS HIGH
TONIGHT INTO THURSDAY. FOR TONIGHT...THE NOSE OF A 35+ KT LOW LEVEL
JET IS EXPECTED TO SET UP ACROSS NORTHEASTERN IOWA AND SOUTHERN
WISCONSIN. THE MODEL GUIDANCE HAS BEEN HITTING THIS AREA HARD
TONIGHT FOR AREAS OF CONVECTION WITH A HEAVY RAIN THREAT.
HOWEVER...REGIONAL SATELLITE IMAGERY ACROSS EASTERN IOWA INDICATES NO
IMMEDIATE THREAT FOR CONVECTIVE DEVELOPMENT UNTIL YOU GET INTO
SOUTHERN MINNESOTA. IN ADDITION...THE 00 UTC OBSERVED SOUNDING OUT
OF KDVN INDICATES A STRONG EML CAPPING INVERSION AROUND 700 MB. WITH
THIS IN PLACE IT WILL BE HARD TO GET CONVECTION TO FIRE ANYTIME SOON
NEAR NORTHERN ILLINOIS. THEREFORE...I HAVE DECIDED TO PULL THE
THUNDER THREAT LATER THIS EVENING OUT OF KRFD WITH THE 00 UTC TAFS.
CONVECTIVE CHANCES ARE POSSIBLE ON THURSDAY...AND THESE CHANCES WILL
LIKELY BE INFLUENCED BY ANY RESIDUAL OUTFLOW BOUNDARIES THAT DEVELOP
FROM CONVECTIVE ACTIVITY TONIGHT ACROSS WISCONSIN. OVERALL
CONFIDENCE IS TOO LOW TO INCLUDE A MENTION OF THUNDER AT THIS TIME.
IT APPEARS SLIGHTLY BETTER CHANCES FOR THUNDERSTORMS WILL OCCUR BY
THURSDAY EVENING AS SOME MID LEVEL DISTURBANCES INTERACT WITH A
FRONTAL ZONE APPROACHING THE AREA. I INCLUDED A VCSH IN THE 30 HR ORD
TAF TO INDICATE THIS THINKING.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* VERY LOW CONFIDENCE ON TSRA AFFECTING THE TERMINALS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS THROUGH THE PERIOD.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH PERIODIC
CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE FRIDAY
INTO THE WEEKEND.
KJB
&&
.MARINE...
240 PM CDT
GENERALLY SOUTHERLY WINDS SHOULD CONTINUE THROUGH THURSDAY
EVENING...THOUGH PERIODIC PASSAGE OF THUNDERSTORM CLUSTERS COULD
RESULT IN VARIABLE AND AT TIMES STRONGER WINDS. FRONT WILL DROP DOWN
THE LAKE THURSDAY NIGHT INTO FRIDAY MORNING RESULTING IN A WIND
SHIFT TO NORTHERLY TO NORTHEASTERLY. WINDS LIKELY TO REMAIN
NORTHEAST TO EAST INTO EARLY NEXT WEEK AS FRONT REMAINS STALLED OUT
TO THE SOUTHWEST OF THE LAKE AND HIGH PRESSURE REMAINS SITUATED OVER
EASTERN CANADA.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
928 PM CDT WED MAY 2 2012
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE....
HAVE MADE SOME SIGNIFICANT ADJUSTMENTS TO POP/WX GRIDS INTO THE
OVERNIGHT HOURS BASED ON ANALYSIS/CONVECTIVE TRENDS UPSTREAM.
WARM FRONT WHICH LIFTED NORTH OF THE FORECAST AREA EARLIER THIS
MORNING HAS BECOME SOMEWHAT ILL-DEFINED ACROSS WISCONSIN AND LOWER
MICHIGAN THIS EVENING...WHILE A SECONDARY TROUGH/WARM FRONT WAS
NOTED FROM NORTHERN MISSOURI INTO CENTRAL IL/IND ENHANCED FROM
COMBINATION OF RETREATING CONVECTIVE OUTFLOW FROM MORNING MCS AND
DIFFERENTIAL HEATING FROM CLOUD COVER EARLIER IN THE DAY. THIS AREA
HAD BECOME RELATIVELY CLOUD-FREE LATE THIS AFTERNOON IN THE WAKE OF
THE SHORT-WAVE TROUGH AXIS WHICH HAS MOVED EAST OF THE AREA PER
WATER VAPOR IMAGERY AND PROFILER WINDS AT WOLCOTT IN. WHILE AIR MASS
IS WARM AND RATHER HUMID...WITH TEMPS STILL IN MID 70S AND DEW
POINTS IN THE MID-UPPER 60S ACROSS SOUTHERN CWA...00Z RAOBS FROM DVN
AND ILX DEPICT STRONG CAPPING INVERSION EXISTS FOR SFC/NEAR SFC
BASED CONVECTION. IN ADDITION...AIR MASS TO THE WEST ACROSS IOWA HAS
REMAINED STABILIZED WITH EXTENSIVE STRATUS DECK THROUGH THE
AFTERNOON AND HAS PREVENTED NEAR SFC BASED CONVECTION FROM
DEVELOPING SAVE FAR SOUTHERN MN/EASTERN NEBRASKA AREAS FARTHER NORTH
AND WEST.
CONVECTION-ALLOWING GUIDANCE INCLUDING WRF-NMM AND HRRR/RAP HAVE
BEEN INDICATING SIGNIFICANT CONVECTIVE DEVELOPMENT ACROSS EASTERN
IOWA INTO SOUTHWEST WISCONSIN DURING THE AFTERNOON AND EVENING
HOURS...BUT BASED ON THERMODYNAMIC PROFILES AND PRE-SUNSET VIS
SATELLITE TRENDS...EARLIER RUNS APPEAR TO HAVE OVER-FORECAST EXTENT
OF DEVELOPMENT. SOME FACTORS DO SUPPORT THE POTENTIAL FOR INCREASING
SHRA/TSRA THREAT THIS EVENING...MAINLY WITH BETTER MOIST ASCENT
DEVELOPING ABOVE STABLE BOUNDARY LAYER AS H9-H8 LOW LEVEL JET
INCREASES TO 35-40 KT AND MID-LEVEL SPEED MAX APPROACHES FROM THE
SOUTHWEST WITHIN AND AREA OF VERY STEEP MID-LEVEL LAPSE RATES WITH
EML NOTED IN OAX/DVN SOUNDINGS. AN ISOLATED AREA OF SHOWERS/WEAK
TSRA HAVE DEVELOPED ALONG A CONVERGENCE ZONE ACROSS FAR EASTERN IA
FROM NEAR MUSCATINE TO JUST WEST OF SAVANNA IL...LIKELY A
REPRESENTATION OF WHAT THE WRF-NMM AND HRRR/RAP WERE TRYING TO
DEPICT BUT ON A MORE LIMITED SCALE. TREND FROM THESE MODELS WOULD
SUGGEST THIS ACTIVITY WILL LIKELY FOCUS MORE ACROSS OUR FAR
NORTHWEST/NORTHERN CWA INTO THE OVERNIGHT HOURS...AND PERHAPS MORE
SO OVER SOUTHERN WI WHERE BETTER DEEP MOIST CONVERGENCE IS NOTED IN
ASSOCIATION WITH SYNOPTIC H9-H8 WARM FRONT. BASED ON ALL OF THIS...
HAVE GENERALLY LOWERED/REMOVED POPS ACROSS THE SOUTHERN CWA
OVERNIGHT. THE RECENT HRRR RUNS WOULD EVEN SUGGEST WE MAY BE DRY
ACROSS THE NORTH EXCEPT FOR RIGHT ALONG THE WI/IL LINE AFTER
MIDNIGHT...THOUGH MY CONFIDENCE IS NOT HIGH ENOUGH TO PULL POPS WITH
UNCERTAIN EVOLUTION OF CONVECTION CURRENTLY FARTHER UPSTREAM. THUS
HAVE GENERALLY LEFT HIGHER POPS GENERALLY NORTH OF I-88 ACROSS
NORTHERN IL...WITH FAR SOUTHERN COUNTIES DRY. HRRR ALSO INDICATES
MCS DEVELOPMENT ACROSS NEBRASKA...WHERE KS/NEBR ACTIVITY IS
CURRENTLY JUST GETTING GOING. LATEST GUIDANCE INDICATES THIS WOULD
NOT ARRIVE UNTIL AFTER 12Z WEDNESDAY IN DECAYING FORM.
RATZER
//PREV DISCUSSION...
329 PM CDT
MAIN FORECAST CHALLENGES REVOLVE AROUND SHOWER/THUNDERSTORM
CHANCES OVER THE NEXT SEVERAL DAYS WITH THE SEVERE POTENTIAL
REMAINING FOR TONIGHT AS WELL AS THURSDAY NIGHT...WITH HIGH
TEMPERATURES BEING DICTATED BY REMNANT PRECIP/CLOUD COVER THROUGH
EACH DAY.
LATEST RADAR IMAGERY DEPICTING AREA OF SHOWERS AND THUNDERSTORMS
WHICH SLOWLY PROGRESSED THROUGH PORTIONS OF THE CWA...CONTINUING
TO DIMINISH THIS AFTERNOON WITH MOST AREAS CURRENTLY DRY. EXPECT
THESE RELATIVELY DRY CONDITIONS TO REMAIN FOR A PORTION OF THIS
AFTERNOON INTO EARLY EVENING...OUTSIDE OF SOME ISOLATED/BRIEF
SHOWERS AND THUNDERSTORMS POSSIBLY DEVELOPING ALONG LINGERING
OUTFLOW BOUNDARIES WHICH SEVERAL ARE CURRENTLY SITUATED OVER THE
CWA. ANY SHOWERS/THUNDERSTORMS WHICH DO DEVELOP THIS AFTERNOON
SHOULD NOT BECOME SEVERE AS INSTABILITY IS STILL LACKING DUE TO A
RECOVERING ENVIRONMENT AND STRONGER WESTERLIES REMAINING TO THE
NORTHWEST.
STRONG SOUTHERLY FLOW OUT AHEAD OF A TROUGH OF LOW PRESSURE WELL
TO THE WEST OVER THE CENTRAL PLAINS WILL HELP FOR THE ENVIRONMENT
OVER THE CWA TO TO SLIGHTLY RECOVER THIS EVENING THROUGH EARLY
THURSDAY MORNING BRINGING LOW TO MID 60S DEWPOINT AIR BACK NORTH
ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS SHOULD HELP
TO INCREASE OVERALL INSTABILITY OVER THE CWA THIS EVENING WHICH
COULD PROVIDE A SETUP FOR ANOTHER ROUND OF THUNDERSTORMS TO RACE
ACROSS THE CWA. MODEL GUIDANCE CONTINUES TO BE ALL OVER THE PLACE
IN REGARDS TO ENVIRONMENTAL DETAILS DUE TO MESOCALE FEATURES WHICH
CONTINUE TO DISRUPT THE LARGE SCALE PATTERN. THIS IS TRANSLATING
TO A LACK OF CONFIDENCE IN MODEL GENERATED PRECIP IN THE NEAR TERM
AS WELL AS FOR THE NEXT SEVERAL DAYS. DESPITE THIS LACK OF
CONFIDENCE IN NUMERICAL GUIDANCE...CAN STILL MAKE OUT SOME OF AREA
FOCUS FOR THUNDERSTORM DEVELOPMENT. ENVIRONMENT SHOULD CONTINUE TO
RECOVER ACROSS THE ENTIRE REGION FROM THE CENTRAL PLAINS BACK EAST
TO THE GREAT LAKES REGION WITH DEEP MOISTURE BACK ON THE RISE.
MAIN INSTABILITY AXIS IS SITUATED FROM WESTERN IOWA EAST INTO
SOUTHERN WISCONSIN...WITH INSTABILITY ANTICIPATED TO CONTINUE TO
INCREASE OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THE EXTENT OF THIS INCREASE OVER THE CWA IS STILL IN
QUESTION...WHICH WILL PLAY A FACTOR IN THUNDERSTORM INTENSITY
TONIGHT. A SUBTLE MID LEVEL IMPULSE CURRENTLY OBSERVED EJECTING
ACROSS THE CENTRAL PLAINS COINCIDING WITH AN INCREASING LLJ SHOULD
INTERACT WITH A FRONTAL BOUNDARY OVER THE CENTRAL PLAINS LATER
THIS EVENING AND HELP FOR THE DEVELOPMENT OF THUNDERSTORMS ACROSS
IOWA. INSTABILITY SHOULD BE MORE THAN ENOUGH TO GET ROBUST
DEVELOPMENT WITH STEERING FLOW/LOW LEVEL SHEAR HELPING TO SHIFT
THIS THUNDERSTORM DEVELOPMENT EAST. A GROWING COMPLEX SHOULD WORK
ITS WAY EAST MAINLY AFFECTING THE NORTHERN HALF OF THE CWA LATER
TONIGHT INTO EARLY THURSDAY MORNING. OVERALL INSTABILITY IS STILL
IN QUESTION ACROSS THE CWA...BUT WITH DEEP MOISTURE NOT. IF
INSTABILITY INCREASES...A HAIL AND WIND THREAT WILL BE POSSIBLE
TONIGHT. IF NOT...AM STILL CONCERNED ABOUT THE POTENTIAL FOR VERY
RAIN EFFICIENT THUNDERSTORMS AS A VERY WARM AND JUICY AIRMASS WILL
BE IN PLACE. WITH ANY MCS PASSAGE TONIGHT...COULD ENVISION FURTHER
UPSCALE DEVELOPMENT AS A STRONG LLJ INTERACTS WITH ANY LINGERING
BOUNDARIES. THIS COULD PROVIDE A SETUP FOR TRAINING OF
THUNDERSTORMS AND HEAVY RAINFALL INTO THURSDAY MORNING.
ADVECTION OF A MUCH WARMER AIRMASS WILL CONTINUE ON THURSDAY WITH
WELL ABOVE NORMAL TEMPERATURES FORECAST. HAVE MAINTAINED MID AND
UPPER 80S FOR THE SOUTHERN HALF OF THE CWA BUT HAVE LOWERED TEMPS
TO AROUND 80 FOR THE NORTHERN HALF DUE TO POSSIBLE LINGERING
CONVECTION AND CLOUD COVER THURSDAY MORNING. ONGOING CONVECTION
DURING THE DAY THURSDAY WILL DEFINITELY BE KEY WITH FURTHER
DEVELOPMENT FOR THE REMAINDER OF THURSDAY INTO FRIDAY
MORNING...WHICH ONCE AGAIN SEEMS PROBABLE. ADVECTION OF A WARM AND
VERY MOIST AIR WILL CONTINUE AIDING IN INSTABILITY WITH THE SETUP
WHICH IS POSSIBLE TONIGHT LIKELY OCCURRING OVER NORTHERN ILLINOIS
ON THURSDAY. THIS WILL BRING ANOTHER ROUND OF THUNDERSTORMS WHICH
WILL BE CAPABLE OF PRODUCING LARGE HAIL/DAMAGING WINDS AND HAIL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* THUNDERSTORM POTENTIAL TONIGHT.
KJB
//DISCUSSION...UPDATED 02Z...
IN SPITE OF THE CAP NOTED IN THE PREVIOUS DISCUSSION RAPID
MOISTENING WITHIN A WARM AIR ADVECTION REGIME HAS LEAD TO THE
DEVELOPMENT OF A CLUSTER OF THUNDERSTORMS ACROSS EAST CENTRAL IOWA
AND PORTIONS OF FAR NORTHWESTERN ILLINOIS. IT APPEARS THE MAIN
THREAT FOR CONVECTION WILL REMAIN ACROSS NORTHWESTERN ILLINOIS AND
INTO WISCONSIN TONIGHT. SOME STORMS MAY GET IN THE VICINITY OF
KRFD AFTER 04 UTC. HOWEVER...THE DIRECTION OF MOVEMENT SHOULD KEEP
A MAJORITY OF THIS ACTIVITY TO THE WEST AND NORTH OF KRFD.
//DISCUSSION...UPDATED 00Z...
THE MAIN CONCERNS DURING THE PERIOD WILL BE TRYING TO PIN DOWN THE
BEST POTENTIAL FOR CONVECTION.
UNFORTUNATELY UNCERTAINTY ON THE OVERALL CONVECTIVE THREAT IS HIGH
TONIGHT INTO THURSDAY. FOR TONIGHT...THE NOSE OF A 35+ KT LOW LEVEL
JET IS EXPECTED TO SET UP ACROSS NORTHEASTERN IOWA AND SOUTHERN
WISCONSIN. THE MODEL GUIDANCE HAS BEEN HITTING THIS AREA HARD
TONIGHT FOR AREAS OF CONVECTION WITH A HEAVY RAIN THREAT.
HOWEVER...REGIONAL SATELLITE IMAGERY ACROSS EASTERN IOWA INDICATES NO
IMMEDIATE THREAT FOR CONVECTIVE DEVELOPMENT UNTIL YOU GET INTO
SOUTHERN MINNESOTA. IN ADDITION...THE 00 UTC OBSERVED SOUNDING OUT
OF KDVN INDICATES A STRONG EML CAPPING INVERSION AROUND 700 MB. WITH
THIS IN PLACE IT WILL BE HARD TO GET CONVECTION TO FIRE ANYTIME SOON
NEAR NORTHERN ILLINOIS. THEREFORE...I HAVE DECIDED TO PULL THE
THUNDER THREAT LATER THIS EVENING OUT OF KRFD WITH THE 00 UTC TAFS.
CONVECTIVE CHANCES ARE POSSIBLE ON THURSDAY...AND THESE CHANCES WILL
LIKELY BE INFLUENCED BY ANY RESIDUAL OUTFLOW BOUNDARIES THAT DEVELOP
FROM CONVECTIVE ACTIVITY TONIGHT ACROSS WISCONSIN. OVERALL
CONFIDENCE IS TOO LOW TO INCLUDE A MENTION OF THUNDER AT THIS TIME.
IT APPEARS SLIGHTLY BETTER CHANCES FOR THUNDERSTORMS WILL OCCUR BY
THURSDAY EVENING AS SOME MID LEVEL DISTURBANCES INTERACT WITH A
FRONTAL ZONE APPROACHING THE AREA. I INCLUDED A VCSH IN THE 30 HR ORD
TAF TO INDICATE THIS THINKING.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* VERY LOW CONFIDENCE ON TSRA AFFECTING THE TERMINALS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS THROUGH THE PERIOD.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH PERIODIC
CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE FRIDAY
INTO THE WEEKEND.
KJB
&&
.MARINE...
240 PM CDT
GENERALLY SOUTHERLY WINDS SHOULD CONTINUE THROUGH THURSDAY
EVENING...THOUGH PERIODIC PASSAGE OF THUNDERSTORM CLUSTERS COULD
RESULT IN VARIABLE AND AT TIMES STRONGER WINDS. FRONT WILL DROP DOWN
THE LAKE THURSDAY NIGHT INTO FRIDAY MORNING RESULTING IN A WIND
SHIFT TO NORTHERLY TO NORTHEASTERLY. WINDS LIKELY TO REMAIN
NORTHEAST TO EAST INTO EARLY NEXT WEEK AS FRONT REMAINS STALLED OUT
TO THE SOUTHWEST OF THE LAKE AND HIGH PRESSURE REMAINS SITUATED OVER
EASTERN CANADA.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
841 PM CDT WED MAY 2 2012
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE....
HAVE MADE SOME SIGNIFICANT ADJUSTMENTS TO POP/WX GRIDS INTO THE
OVERNIGHT HOURS BASED ON ANALYSIS/CONVECTIVE TRENDS UPSTREAM.
WARM FRONT WHICH LIFTED NORTH OF THE FORECAST AREA EARLIER THIS
MORNING HAS BECOME SOMEWHAT ILL-DEFINED ACROSS WISCONSIN AND LOWER
MICHIGAN THIS EVENING...WHILE A SECONDARY TROUGH/WARM FRONT WAS
NOTED FROM NORTHERN MISSOURI INTO CENTRAL IL/IND ENHANCED FROM
COMBINATION OF RETREATING CONVECTIVE OUTFLOW FROM MORNING MCS AND
DIFFERENTIAL HEATING FROM CLOUD COVER EARLIER IN THE DAY. THIS AREA
HAD BECOME RELATIVELY CLOUD-FREE LATE THIS AFTERNOON IN THE WAKE OF
THE SHORT-WAVE TROUGH AXIS WHICH HAS MOVED EAST OF THE AREA PER
WATER VAPOR IMAGERY AND PROFILER WINDS AT WOLCOTT IN. WHILE AIR MASS
IS WARM AND RATHER HUMID...WITH TEMPS STILL IN MID 70S AND DEW
POINTS IN THE MID-UPPER 60S ACROSS SOUTHERN CWA...00Z RAOBS FROM DVN
AND ILX DEPICT STRONG CAPPING INVERSION EXISTS FOR SFC/NEAR SFC
BASED CONVECTION. IN ADDITION...AIR MASS TO THE WEST ACROSS IOWA HAS
REMAINED STABILIZED WITH EXTENSIVE STRATUS DECK THROUGH THE
AFTERNOON AND HAS PREVENTED NEAR SFC BASED CONVECTION FROM
DEVELOPING SAVE FAR SOUTHERN MN/EASTERN NEBRASKA AREAS FARTHER NORTH
AND WEST.
CONVECTION-ALLOWING GUIDANCE INCLUDING WRF-NMM AND HRRR/RAP HAVE
BEEN INDICATING SIGNIFICANT CONVECTIVE DEVELOPMENT ACROSS EASTERN
IOWA INTO SOUTHWEST WISCONSIN DURING THE AFTERNOON AND EVENING
HOURS...BUT BASED ON THERMODYNAMIC PROFILES AND PRE-SUNSET VIS
SATELLITE TRENDS...EARLIER RUNS APPEAR TO HAVE OVER-FORECAST EXTENT
OF DEVELOPMENT. SOME FACTORS DO SUPPORT THE POTENTIAL FOR INCREASING
SHRA/TSRA THREAT THIS EVENING...MAINLY WITH BETTER MOIST ASCENT
DEVELOPING ABOVE STABLE BOUNDARY LAYER AS H9-H8 LOW LEVEL JET
INCREASES TO 35-40 KT AND MID-LEVEL SPEED MAX APPROACHES FROM THE
SOUTHWEST WITHIN AND AREA OF VERY STEEP MID-LEVEL LAPSE RATES WITH
EML NOTED IN OAX/DVN SOUNDINGS. AN ISOLATED AREA OF SHOWERS/WEAK
TSRA HAVE DEVELOPED ALONG A CONVERGENCE ZONE ACROSS FAR EASTERN IA
FROM NEAR MUSCATINE TO JUST WEST OF SAVANNA IL...LIKELY A
REPRESENTATION OF WHAT THE WRF-NMM AND HRRR/RAP WERE TRYING TO
DEPICT BUT ON A MORE LIMITED SCALE. TREND FROM THESE MODELS WOULD
SUGGEST THIS ACTIVITY WILL LIKELY FOCUS MORE ACROSS OUR FAR
NORTHWEST/NORTHERN CWA INTO THE OVERNIGHT HOURS...AND PERHAPS MORE
SO OVER SOUTHERN WI WHERE BETTER DEEP MOIST CONVERGENCE IS NOTED IN
ASSOCIATION WITH SYNOPTIC H9-H8 WARM FRONT. BASED ON ALL OF THIS...
HAVE GENERALLY LOWERED/REMOVED POPS ACROSS THE SOUTHERN CWA
OVERNIGHT. THE RECENT HRRR RUNS WOULD EVEN SUGGEST WE MAY BE DRY
ACROSS THE NORTH EXCEPT FOR RIGHT ALONG THE WI/IL LINE AFTER
MIDNIGHT...THOUGH MY CONFIDENCE IS NOT HIGH ENOUGH TO PULL POPS WITH
UNCERTAIN EVOLUTION OF CONVECTION CURRENTLY FARTHER UPSTREAM. THUS
HAVE GENERALLY LEFT HIGHER POPS GENERALLY NORTH OF I-88 ACROSS
NORTHERN IL...WITH FAR SOUTHERN COUNTIES DRY. HRRR ALSO INDICATES
MCS DEVELOPMENT ACROSS NEBRASKA...WHERE KS/NEBR ACTIVITY IS
CURRENTLY JUST GETTING GOING. LATEST GUIDANCE INDICATES THIS WOULD
NOT ARRIVE UNTIL AFTER 12Z WEDNESDAY IN DECAYING FORM.
RATZER
&&
.PREV DISCUSSION...
329 PM CDT
MAIN FORECAST CHALLENGES REVOLVE AROUND SHOWER/THUNDERSTORM
CHANCES OVER THE NEXT SEVERAL DAYS WITH THE SEVERE POTENTIAL
REMAINING FOR TONIGHT AS WELL AS THURSDAY NIGHT...WITH HIGH
TEMPERATURES BEING DICTATED BY REMNANT PRECIP/CLOUD COVER THROUGH
EACH DAY.
LATEST RADAR IMAGERY DEPICTING AREA OF SHOWERS AND THUNDERSTORMS
WHICH SLOWLY PROGRESSED THROUGH PORTIONS OF THE CWA...CONTINUING
TO DIMINISH THIS AFTERNOON WITH MOST AREAS CURRENTLY DRY. EXPECT
THESE RELATIVELY DRY CONDITIONS TO REMAIN FOR A PORTION OF THIS
AFTERNOON INTO EARLY EVENING...OUTSIDE OF SOME ISOLATED/BRIEF
SHOWERS AND THUNDERSTORMS POSSIBLY DEVELOPING ALONG LINGERING
OUTFLOW BOUNDARIES WHICH SEVERAL ARE CURRENTLY SITUATED OVER THE
CWA. ANY SHOWERS/THUNDERSTORMS WHICH DO DEVELOP THIS AFTERNOON
SHOULD NOT BECOME SEVERE AS INSTABILITY IS STILL LACKING DUE TO A
RECOVERING ENVIRONMENT AND STRONGER WESTERLIES REMAINING TO THE
NORTHWEST.
STRONG SOUTHERLY FLOW OUT AHEAD OF A TROUGH OF LOW PRESSURE WELL
TO THE WEST OVER THE CENTRAL PLAINS WILL HELP FOR THE ENVIRONMENT
OVER THE CWA TO TO SLIGHTLY RECOVER THIS EVENING THROUGH EARLY
THURSDAY MORNING BRINGING LOW TO MID 60S DEWPOINT AIR BACK NORTH
ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS SHOULD HELP
TO INCREASE OVERALL INSTABILITY OVER THE CWA THIS EVENING WHICH
COULD PROVIDE A SETUP FOR ANOTHER ROUND OF THUNDERSTORMS TO RACE
ACROSS THE CWA. MODEL GUIDANCE CONTINUES TO BE ALL OVER THE PLACE
IN REGARDS TO ENVIRONMENTAL DETAILS DUE TO MESOCALE FEATURES WHICH
CONTINUE TO DISRUPT THE LARGE SCALE PATTERN. THIS IS TRANSLATING
TO A LACK OF CONFIDENCE IN MODEL GENERATED PRECIP IN THE NEAR TERM
AS WELL AS FOR THE NEXT SEVERAL DAYS. DESPITE THIS LACK OF
CONFIDENCE IN NUMERICAL GUIDANCE...CAN STILL MAKE OUT SOME OF AREA
FOCUS FOR THUNDERSTORM DEVELOPMENT. ENVIRONMENT SHOULD CONTINUE TO
RECOVER ACROSS THE ENTIRE REGION FROM THE CENTRAL PLAINS BACK EAST
TO THE GREAT LAKES REGION WITH DEEP MOISTURE BACK ON THE RISE.
MAIN INSTABILITY AXIS IS SITUATED FROM WESTERN IOWA EAST INTO
SOUTHERN WISCONSIN...WITH INSTABILITY ANTICIPATED TO CONTINUE TO
INCREASE OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THE EXTENT OF THIS INCREASE OVER THE CWA IS STILL IN
QUESTION...WHICH WILL PLAY A FACTOR IN THUNDERSTORM INTENSITY
TONIGHT. A SUBTLE MID LEVEL IMPULSE CURRENTLY OBSERVED EJECTING
ACROSS THE CENTRAL PLAINS COINCIDING WITH AN INCREASING LLJ SHOULD
INTERACT WITH A FRONTAL BOUNDARY OVER THE CENTRAL PLAINS LATER
THIS EVENING AND HELP FOR THE DEVELOPMENT OF THUNDERSTORMS ACROSS
IOWA. INSTABILITY SHOULD BE MORE THAN ENOUGH TO GET ROBUST
DEVELOPMENT WITH STEERING FLOW/LOW LEVEL SHEAR HELPING TO SHIFT
THIS THUNDERSTORM DEVELOPMENT EAST. A GROWING COMPLEX SHOULD WORK
ITS WAY EAST MAINLY AFFECTING THE NORTHERN HALF OF THE CWA LATER
TONIGHT INTO EARLY THURSDAY MORNING. OVERALL INSTABILITY IS STILL
IN QUESTION ACROSS THE CWA...BUT WITH DEEP MOISTURE NOT. IF
INSTABILITY INCREASES...A HAIL AND WIND THREAT WILL BE POSSIBLE
TONIGHT. IF NOT...AM STILL CONCERNED ABOUT THE POTENTIAL FOR VERY
RAIN EFFICIENT THUNDERSTORMS AS A VERY WARM AND JUICY AIRMASS WILL
BE IN PLACE. WITH ANY MCS PASSAGE TONIGHT...COULD ENVISION FURTHER
UPSCALE DEVELOPMENT AS A STRONG LLJ INTERACTS WITH ANY LINGERING
BOUNDARIES. THIS COULD PROVIDE A SETUP FOR TRAINING OF
THUNDERSTORMS AND HEAVY RAINFALL INTO THURSDAY MORNING.
ADVECTION OF A MUCH WARMER AIRMASS WILL CONTINUE ON THURSDAY WITH
WELL ABOVE NORMAL TEMPERATURES FORECAST. HAVE MAINTAINED MID AND
UPPER 80S FOR THE SOUTHERN HALF OF THE CWA BUT HAVE LOWERED TEMPS
TO AROUND 80 FOR THE NORTHERN HALF DUE TO POSSIBLE LINGERING
CONVECTION AND CLOUD COVER THURSDAY MORNING. ONGOING CONVECTION
DURING THE DAY THURSDAY WILL DEFINITELY BE KEY WITH FURTHER
DEVELOPMENT FOR THE REMAINDER OF THURSDAY INTO FRIDAY
MORNING...WHICH ONCE AGAIN SEEMS PROBABLE. ADVECTION OF A WARM AND
VERY MOIST AIR WILL CONTINUE AIDING IN INSTABILITY WITH THE SETUP
WHICH IS POSSIBLE TONIGHT LIKELY OCCURRING OVER NORTHERN ILLINOIS
ON THURSDAY. THIS WILL BRING ANOTHER ROUND OF THUNDERSTORMS WHICH
WILL BE CAPABLE OF PRODUCING LARGE HAIL/DAMAGING WINDS AND HAIL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* THUNDERSTORM POTENTIAL TONIGHT.
KJB
//DISCUSSION...UPDATED 00Z...
THE MAIN CONCERNS DURING THE PERIOD WILL BE TRYING TO PIN DOWN THE
BEST POTENTIAL FOR CONVECTION.
UNFORTUNATELY UNCERTAINTY ON THE OVERALL CONVECTIVE THREAT IS HIGH
TONIGHT INTO THURSDAY. FOR TONIGHT...THE NOSE OF A 35+ KT LOW LEVEL
JET IS EXPECTED TO SET UP ACROSS NORTHEASTERN IOWA AND SOUTHERN
WISCONSIN. THE MODEL GUIDANCE HAS BEEN HITTING THIS AREA HARD
TONIGHT FOR AREAS OF CONVECTION WITH A HEAVY RAIN THREAT.
HOWEVER...REGIONAL SATELLITE IMAGERY ACROSS EASTERN IOWA INDICATES NO
IMMEDIATE THREAT FOR CONVECTIVE DEVELOPMENT UNTIL YOU GET INTO
SOUTHERN MINNESOTA. IN ADDITION...THE 00 UTC OBSERVED SOUNDING OUT
OF KDVN INDICATES A STRONG EML CAPPING INVERSION AROUND 700 MB. WITH
THIS IN PLACE IT WILL BE HARD TO GET CONVECTION TO FIRE ANYTIME SOON
NEAR NORTHERN ILLINOIS. THEREFORE...I HAVE DECIDED TO PULL THE
THUNDER THREAT LATER THIS EVENING OUT OF KRFD WITH THE 00 UTC TAFS.
CONVECTIVE CHANCES ARE POSSIBLE ON THURSDAY...AND THESE CHANCES WILL
LIKELY BE INFLUENCED BY ANY RESIDUAL OUTFLOW BOUNDARIES THAT DEVELOP
FROM CONVECTIVE ACTIVITY TONIGHT ACROSS WISCONSIN. OVERALL
CONFIDENCE IS TOO LOW TO INCLUDE A MENTION OF THUNDER AT THIS TIME.
IT APPEARS SLIGHTLY BETTER CHANCES FOR THUNDERSTORMS WILL OCCUR BY
THURSDAY EVENING AS SOME MID LEVEL DISTURBANCES INTERACT WITH A
FRONTAL ZONE APPROACHING THE AREA. I INCLUDED A VCSH IN THE 30 HR ORD
TAF TO INDICATE THIS THINKING.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* VERY LOW CONFIDENCE ON TSRA AFFECTING THE TERMINALS OVERNIGHT.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS THROUGH THE PERIOD.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH PERIODIC
CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE FRIDAY
INTO THE WEEKEND.
KJB
&&
.MARINE...
240 PM CDT
GENERALLY SOUTHERLY WINDS SHOULD CONTINUE THROUGH THURSDAY
EVENING...THOUGH PERIODIC PASSAGE OF THUNDERSTORM CLUSTERS COULD
RESULT IN VARIABLE AND AT TIMES STRONGER WINDS. FRONT WILL DROP DOWN
THE LAKE THURSDAY NIGHT INTO FRIDAY MORNING RESULTING IN A WIND
SHIFT TO NORTHERLY TO NORTHEASTERLY. WINDS LIKELY TO REMAIN
NORTHEAST TO EAST INTO EARLY NEXT WEEK AS FRONT REMAINS STALLED OUT
TO THE SOUTHWEST OF THE LAKE AND HIGH PRESSURE REMAINS SITUATED OVER
EASTERN CANADA.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
303 PM CDT TUE MAY 1 2012
.DISCUSSION...
ISSUED 300 PM CDT TUE MAY 1 2012
A WET BIAS IS INDICATED IN ALL OF THE DETERMINISTIC MODELS AS A
FRONTAL BOUNDARY LIFTS NORTH AS A WARM FRONT TONIGHT...THEN LINGERS
JUST W-NW OF ILLINOIS FOR MUCH OF THE WEEK BEFORE RETURNING AS A
COLD FRONT LATER IN THE WEEKEND. A WARM AND HUMID AIRMASS WILL
DEVELOP OVER C IL TOMORROW BEHIND THE WARM FRONT. THAT SUMMER-
TIME TYPE OF AIRMASS WILL BE RIPE FOR ANY UPPER SHORTWAVES AND
LINGERING SURFACE BOUNDARIES TO BECOME ACTIVE WITH STORMS WHEN ANY
ELEVATED MIXED LAYERS BECOME UNSTABLE ENOUGH FOR SUSTAINED
UPDRAFTS. THE END RESULT IS AN ABUNDANCE OF PRECIP CHANCES
PEPPERED THROUGHOUT THE NEXT 7 DAYS...BUT CONFIDENCE ON RAIN/STORM
COVERAGE IN GENERAL IS LOW.
SHORT TERM...TONIGHT THROUGH THURSDAY.
THE WARM FRONT IS CURRENTLY EXTENDING FROM LOW PRESSURE NEAR
FULTON COUNTY TO THE SE TOWARD TERRE HAUTE. AN MCV ASSOCIATED WITH
THE SURFACE LOW WILL HELP TRIGGER ADDITIONAL SHOWERS AND A FEW
STORMS ACROSS THE NORTH INTO THE EVENING. ADDITIONAL STORMS WILL
BE POSSIBLE ACROSS THE SOUTH INTO THE EVENING AS THE SOUTHERN
PERIPHERY OF THE MCV REMAINS ACTIVE WHERE SUNSHINE WAS MORE
PLENTIFUL TODAY. WE KEPT SLIGHT CHANCE POPS IN ALL AREAS TONIGHT
TO ACCOUNT FOR VARIOUS CONVECTIVE ELEMENTS THAT MAY FESTER UNDER
THE ADVANCING WARM FRONT IN THE NORTH AND THE POST MCV AIRMASS IN
THE SOUTH.
IN OUR COUNTIES...WEDNESDAY SHOULD BE CAPPED WITH WARM AIR ALOFT
FOR MOST OF THE DAY. OUR NORTHERN COUNTIES ARE IN THE DAY 2
SLIGHT RISK FOR SEVERE STORMS...CLOSER TO THE LINGERING WARM
FRONT. THE HRRR MODEL IS SHOWING AN ADVANCING STORM COMPLEX LATER
TONIGHT ACROSS MN/IA. THAT SYSTEM MAY PUT DOWN AN ADDITIONAL
BOUNDARY FROM THE COLD POOL THAT DRIFTS EAST TOWARD IL WED
MORNING. IT MAY BECOME ACTIVE AS PEAK HEATING CREATES SURFACE
BASED INSTABILITY. EVEN IF MORNING CLOUDS AND FOG LINGER IN THAT
AREA THROUGH THE MORNING...ANY EARLY AFTERNOON CLEARING WILL
ALLOW FOR RAPID DESTABILIZATION OF THE AIRMASS IN FAR NW IL AND
AREAS TO THE W-NW NEAR THE WARM FRONT. IF THE CAP BREAKS TO THE
NW...THE STORMS MAY MAINTAIN SEVERE LEVELS INTO SOME OF OUR
COUNTIES...BUT THE FARTHER E-SE THEY PROGRESS INTO THE CAPPED
AIRMASS...THEY SHOULD LOSE SOME STRENGTH. THEREFORE WE ONLY HAVE
SLIGHT CHANCE POPS IN OUR NORTHERN COUNTIES WED/WED NIGHT.
THURSDAY MAY BE A SIMILAR SCENARIO TO WEDNESDAY...AS THE WARM
FRONT/STATIONARY FRONT REMAINS IN PLACE TO OUR NW. OUR NW COUNTIES
ARE IN THE DAY 3 SLIGHT RISK FOR SEVERE STORMS AGAIN AS A RESULT.
NEAR RECORD HIGHS IN THE MID TO UPPER 80S ARE EXPECTED WED AND
THUR AS DEWPOINTS CLIMB INTO THE MID 60S. IT WILL BE AN
UNCOMFORTABLE AIRMASS AFTER THE RELATIVELY COOLER PORTIONS OF
APRIL.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY.
STORM CHANCES WILL INCREASE FROM NW TO SE ON THURSDAY NIGHT AS LOW
PRESSURE MOVES FROM THE DAKOTAS INTO THE GREAT LAKES...DRAGGING A
COLD FRONT TOWARD NW IL. STORM CHANCES WILL CONTINUE FRI AND FRI
NIGHT AS THE FRONT STALLS OUT ACROSS SOUTH CENTRAL IL. SATURDAY
MAY SEE A BREAK IN THE ACTION BUT SLIGHT CHANCES WILL CONTINUE DUE
TO THE PROXIMITY OF THE FRONT AND 500MB SHORTWAVES.
HIGHER CHANCES OF SHOWERS AND STORMS WILL DEVELOP LATER SUNDAY
INTO MONDAY AS THE NEXT LOW PRESSURE CENTER MOVES FROM THE CENTRAL
PLAINS INTO C IL ALONG THE FRONT. A COOLER AIRMASS WILL TRY TO
DROP SOUTH INTO OUR PORTION OF IL ON MONDAY NIGHT AND TUESDAY...AS
HIGH PRESSURE FROM CANADA BUILDS SOUTHWARD. SO WE WENT WITH A
COOLING TREND FOR MON AND TUES...WITH TUES HIGHS REMAINING IN THE
60S.
SHIMON
&&
.AVIATION...
ISSUED 1254 PM CDT TUE MAY 1 2012
LOW-LEVEL CIRCULATION ASSOCIATED WITH OVERNIGHT/EARLY MORNING
CONVECTIVE COMPLEX WILL LIFT NORTHWARD THROUGH THE ILLINOIS RIVER
VALLEY THIS AFTERNOON. TO THE N/NW OF ITS TRACK...WINDS WILL
REMAIN FROM THE EAST AT KPIA FOR THE NEXT COUPLE OF HOURS...THEN
WILL BECOME LIGHT/VARIABLE AS THE FEATURE MOVES NEARBY. ELSEWHERE
AROUND CENTRAL ILLINOIS...SOUTHEASTERLY WINDS WILL BECOME
SOUTHERLY AS A WARM FRONT LIFTS NORTHWARD THROUGH THE AREA. HIGH
RES MODELS SUCH AS THE HRRR SUGGEST WIDELY SCATTERED STORMS
RE-DEVELOPING IN THE WARM SECTOR THIS AFTERNOON...HOWEVER
CONFIDENCE IS TOO LOW TO INCLUDE IN FORECAST AT THIS TIME. FURTHER
NORTHWEST IN CLOSER PROXIMITY TO THE CIRCULATION CENTER...RADAR
LOOPS SUGGEST PERIODIC SHOWERS AT KPIA THROUGH ABOUT 21Z. PRECIP
CHANCES DIMINISH AND SKIES BECOME PARTLY TO MOSTLY CLEAR ACROSS
THE BOARD THIS EVENING...AS WARM FRONT PUSHES INTO NORTHERN
ILLINOIS. DUE TO AMPLE LOW-LEVEL MOISTURE AND HUMID SOUTHERLY FLOW
IN ITS WAKE...MAY SEE SOME FOG AT THE TERMINALS OVERNIGHT. WINDS
OF AROUND 10KT WILL LIKELY PREVENT WIDESPREAD DENSE FOG...HOWEVER
HAVE DROPPED VISBYS TO AROUND 3SM AFTER 09Z. ANY FOG WILL
DISSIPATE BY EARLY WEDNESDAY MORNING...FOLLOWED BY MOSTLY CLEAR
SKIES AND GUSTY S/SW WINDS.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1254 PM CDT TUE MAY 1 2012
.DISCUSSION...
ISSUED 929 AM CDT TUE MAY 1 2012
BAND OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A WELL-DEFINED
MCV OVER NORTHERN MISSOURI CONTINUES TO LIFT NORTHEASTWARD ACROSS
CENTRAL/SOUTHEAST ILLINOIS THIS MORNING. BASED ON RADAR TIMING
TOOLS...MAIN PRECIP AREA WILL BE TO THE N/NE OF THE KILX CWA BY
MIDDAY. IN THE WAKE OF THE MORNING WAVE OF PRECIP...ADDITIONAL
CONVECTION MAY FIRE ALONG/AHEAD OF THE ADVANCING MCV. DUE TO
STABILIZING INFLUENCE OF MORNING PRECIP...THINK AREAL COVERAGE OF
ANY AFTERNOON STORMS WILL BE SCATTERED AT BEST. HAVE THEREFORE
ADJUSTED RAIN CHANCES TO BETTER REFLECT CURRENT TRENDS...FEATURING
CATEGORICAL POPS THIS MORNING...THEN ONLY CHANCE POPS THIS
AFTERNOON. HAVE ALSO TWEAKED HOURLY TEMPS...AS CLOUDS/RAIN WILL
KEEP READINGS IN THE 50S AND 60S THROUGH MIDDAY...BEFORE DRIER
CONDITIONS AND AN INCREASING SOUTHERLY WIND HELP TEMPS SOAR INTO
THE 70S BY MID TO LATE AFTERNOON. ZONE UPDATE HAS ALREADY BEEN
ISSUED.
&&
.AVIATION...
ISSUED 1254 PM CDT TUE MAY 1 2012
LOW-LEVEL CIRCULATION ASSOCIATED WITH OVERNIGHT/EARLY MORNING
CONVECTIVE COMPLEX WILL LIFT NORTHWARD THROUGH THE ILLINOIS RIVER
VALLEY THIS AFTERNOON. TO THE N/NW OF ITS TRACK...WINDS WILL
REMAIN FROM THE EAST AT KPIA FOR THE NEXT COUPLE OF HOURS...THEN
WILL BECOME LIGHT/VARIABLE AS THE FEATURE MOVES NEARBY. ELSEWHERE
AROUND CENTRAL ILLINOIS...SOUTHEASTERLY WINDS WILL BECOME
SOUTHERLY AS A WARM FRONT LIFTS NORTHWARD THROUGH THE AREA. HIGH
RES MODELS SUCH AS THE HRRR SUGGEST WIDELY SCATTERED STORMS
RE-DEVELOPING IN THE WARM SECTOR THIS AFTERNOON...HOWEVER
CONFIDENCE IS TOO LOW TO INCLUDE IN FORECAST AT THIS TIME. FURTHER
NORTHWEST IN CLOSER PROXIMITY TO THE CIRCULATION CENTER...RADAR
LOOPS SUGGEST PERIODIC SHOWERS AT KPIA THROUGH ABOUT 21Z. PRECIP
CHANCES DIMINISH AND SKIES BECOME PARTLY TO MOSTLY CLEAR ACROSS
THE BOARD THIS EVENING...AS WARM FRONT PUSHES INTO NORTHERN
ILLINOIS. DUE TO AMPLE LOW-LEVEL MOISTURE AND HUMID SOUTHERLY FLOW
IN ITS WAKE...MAY SEE SOME FOG AT THE TERMINALS OVERNIGHT. WINDS
OF AROUND 10KT WILL LIKELY PREVENT WIDESPREAD DENSE FOG...HOWEVER
HAVE DROPPED VISBYS TO AROUND 3SM AFTER 09Z. ANY FOG WILL
DISSIPATE BY EARLY WEDNESDAY MORNING...FOLLOWED BY MOSTLY CLEAR
SKIES AND GUSTY S/SW WINDS.
BARNES
&&
.PREV DISCUSSION...
ISSUED 356 AM CDT TUE MAY 1 2012
WEAK HIGH PRESSURE DOMINANCE SLOWLY COMING TO AN END AS ANOTHER
UPPER LEVEL DISTURBANCE AND CONVECTIVE COMPLEX SLOWLY MAKES ITS
WAY THROUGH THE PLAINS AND INTO THE MIDWEST THIS MORNING. STRONG
WAA STILL KEEPING THE TEMPS UP THROUGHOUT THE ENTIRE FORECAST PD.
INHERITED FORECAST A COMPILATION OF MANY CHANCE POPS IN A RATHER
ACTIVE WEATHER PATTERN AND SEVERAL WAVES PUSHING OUT IN
INCREASINGLY SWRLY FLOW THROUGH THE WEEKEND UNTIL A MAJOR TROF
DIGS INTO THE WESTERN COAST. WITH LARGE SCALE PATTERN SHIFTS...
MODELS HAVING A DIFFICULT TIME WITH WAVE STRENGTH AND TIMING.
FORECAST VERY MUCH A BLEND...WITH LITTLE CHANGES MADE HERE AND
THERE TO TREND OUT SMALL POPS WHERE POSSIBLE.
SHORT TERM...TODAY AND TOMORROW...
PRECIP SPREADING NORTHWARD INTO CWA THIS MORNING RESULTING IN POPS
THROUGH MIDDAY...BUT SHOWERS ALREADY WEAKENING SOMEWHAT ON
APPROACH TO THE MISS RIVER VALLEY INTO THE RIDGE AXIS.
REDEVELOPMENT AND AFTERNOON HEATING WILL PLAY A ROLE IN PRECIP FOR
THE SECOND HALF OF THE DAY...THOUGH THE CLOUD COVER ASSOCIATED
SHOULD MITIGATE THE HEATING. WARM AIR AND INCREASINGLY SOUTHERLY
FLOW AT THE SFC WILL RESULT IN AN EVEN WARMER DAY TOMORROW...AND A
FRONT LIFTING THROUGH THE CWA THROUGH OVERNIGHT HOURS INTO
TOMORROW. BOUNDARY IS MOST PRONOUNCED JUST TO THE NORTH OF THE
CWA...WITH POPS IN THE NRN TIER OF THE STATE FOR TOMORROW AND
TOMORROW EVENING. THIS IS A BIT OF A SHIFT NORTHWARD FROM THE LAST
FEW FORECASTS.
LONG TERM...THURSDAY THROUGH MONDAY...
THOUGH INITIAL SYSTEM LIFTS OUT TO THE EAST...A TROF STARTING TO DIG
INTO THE PAC COAST EJECTS OUT SEVERAL SHORTWAVES THROUGH THE
INCREASINGLY SOUTHWESTERLY FLOW ALOFT...LIGHTING UP A SERIES OF
SHOWER/TS SCENARIOS THROUGH THE LATTER HALF OF THE WEEK AND INTO
THE WEEKEND...ALONG A SFC TROF/BOUNDARY REMAINING OVER THE NRN
TIER OF THE STATE...ALONG THE SAME SW/NE TRAJECTORY. MODEL QPF
STARTING TO SHIFT FURTHER NORTH IN ALL SOLUTIONS. THE TRACK OF
THE WAVES THEMSELVES IS STILL A BIT OF A QUESTION MARK...AND
LEAVING ENOUGH UNCERTAINTY THAT POPS ARE LOW AND NEVER FAR
AWAY...EVEN WITHIN THE EXTENDED. UNSEASONABLY WARM AND MUGGY TEMPS
DOMINATE THE EXTENDED AS WELL...WITH GUIDANCE WELL INTO THE 80S
AND DEWPOINTS IN THE 60S...WHICH WILL ONLY BE ENHANCED BY
LOCALIZED SHOWERS AND THUNDERSTORMS IN THE ACTIVE WAVE TRAIN.
HJSCLS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...CORRECTED
NWS NORTHERN INDIANA
319 PM EDT TUE MAY 1 2012
.SHORT TERM...
MANY ISSUES TO SORT OUT IN THE SHORT TERM. MCV MOVING ACROSS THE
REGION TODAY HAS BEEN HANDLED BEST BY HRRR WITH OTHER HI RES
GUIDANCE IN BALLPARK BUT NOT NEAR AS FAST MOVING THIS WAVE
NORTHEAST. HAVE FOLLOWED HRRR FOR GUIDANCE IN THE SHORT TERM. SHOULD
SEE BULK OF PCPN MOVE EAST BEFORE 00Z WITH LINGERING SHOWERS AND FEW
THUNDERSTORMS FAR EAST AFTER 00Z. MEANWHILE...SOME DEVELOPMENT
POSSIBLE SOUTH OF MCV TRACK IN AREA OF INCREASING INSTABILITY LATE
THIS AFTERNOON WHICH COULD MOVE THROUGH CENTRAL AND NORTHERN AREAS
THIS EVENING. PREVIOUS GRIDS HAD LIKELY POPS ALL NIGHT AND THIS
SEEMS OVERDONE GIVEN FASTER ARRIVAL OF MCV AND INCREASING STABILITY
OVERNIGHT. HAVE ADJUSTED GRIDS FOR HIGHER POPS THIS EVENING BUT KEPT
CHANCE POPS OVERNIGHT WITH BOUNDARY IN THE AREA.
NEXT ISSUE IS WITH DEVELOPMENT OF AN MCS OVERNIGHT TO OUR NW AND
TRACK IT WOULD TAKE TOWARD DAYBREAK. NAM12 BRINGS SOUTHERN FRINGE OF
THIS SYSTEM ACROSS NORTHERN AREAS AROUND 12Z WITH GFS SIMILAR. HI
RES WRF NMM ALSO HINTS AT NORTHERN AREAS BEING BRUSHED BY CONVECTION
EARLY WED MORNING. THIS WARRANTS A SLIGHT NUDGE IN POPS EARLY
WEDNESDAY BUT CONFINED TO MID CHANCE RANGE GIVEN MCS UNCERTAINTY.
NAM AND WRF LAY A BOUNDARY OUT ACROSS CENTRAL CWA WEDNESDAY WHICH
THEN CONVECTS IN THE AFTERNOON WITH GROWING INSTABILITY. THIS
INSTABILITY IS CONTINGENT ON CLOUDS BREAKING UP AND AFTERNOON
HEATING BUT WITH SYNOPTIC WARM FRONT WELL NORTH AND STRONG SOUTHWEST
FLOW ALOFT THIS LOOKS PLAUSIBLE. RESULT WOULD BE TSRA DEVELOPMENT
FARTHER SOUTH IN CENTRAL CWA SO HAVE BROUGHT POPS BACK INTO THIS
AREA FOR THE AFTERNOON HOURS. SEVERE THUNDERSTORMS WOULD BE POSSIBLE
GIVEN MARGINAL BULK SHEAR BUT POTENTIALLY LARGE MUCAPE AND HIGH PWAT
VALUES.
TEMPS WILL BE VERY TRICKY WITH VERY WARM AND HUMID AIRMASS IN PLACE
BUT CONVECTIVE DEBRIS AND PCPN LIMITING FACTORS FOR MAX HEATING. ALL
BLEND USED FOR TEMPERATURES THROUGH THE SHORT TERM PERIOD AS THEY
ARE A NICE COMPROMISE BUT CERTAINLY COULD BE A LITTLE WARMER OR
COOLER DEPENDING ON AMOUNT OF SUN.
&&
.LONG TERM...THURSDAY THROUGH MONDAY
PERIOD TO BEGIN WITH SUBTLE HEIGHT RISES ACROSS THE UPPER
MIDWEST/NORTHERN GREAT LAKES AS MORE SIGNIFICANT SHORT WAVE UPPER
TROUGH AXIS TRACKS INTO THE PACIFIC NORTHWEST. THIS WILL RESULT IN
WARM FRONT TO CONTINUE TO SURGE NORTHWARD ACROSS THE GREAT LAKES
REGION ON THURSDAY. GENERALLY CAPPED CONDITIONS ARE ANTICIPATED
ACROSS APPROXIMATELY SOUTHERN TWO THIRDS OF THE FORECAST AREA WITH
MAIN QUESTION ON PRECIP CHANCES ACROSS THE FAR NORTH WHERE CAP WILL
LIKELY BE WEAKER. DIFFICULT AT THIS FORECAST DISTANCE TO LATCH ONTO
STRONGER PERIODS OF MID/UPPER LEVEL FORCING WITH MAIN SHORT WAVE
TRACK REMAINING WITH STRONGER BELT OF WESTERLIES FROM THE NORTHERN
PLAINS INTO THE UPPER GREAT LAKES. SEE NO REASON TO DEVIATE FROM
PREVIOUS FORECAST AT THIS TIME WITH LATE AFTERNOON LOW CHANCE TSRA
POPS ACROSS THE FAR NORTH GIVEN AFOREMENTIONED THERMODYNAMIC
PROFILES.
THE MORE PRONOUNCED PACIFIC WAVE IS THEN EXPECTED TO TRACK ACROSS
SOUTHWEST ONTARIO BY THURSDAY NIGHT INTO FRIDAY EVENTUALLY ALLOWING
COLD FRONT TO SHIFT EASTWARD. STRONGER FRONTAL CONVERGENCE MAY BE
CONFINED TO AREAS FURTHER NORTH ACROSS THE GREAT LAKES IN CLOSER
PROXIMITY TO STRONGER UPPER FORCING. HOWEVER WITH MODERATE
INSTABILITY PRECEDING THE FRONT WILL CONTINUE WITH MID RANGE
CHANCE POPS THURSDAY NIGHT THROUGH FRIDAY ACROSS ENTIRE FORECAST
AREA. SEVERE POTENTIAL STILL UNCLEAR FOR THURSDAY NIGHT/FRIDAY DUE
TO UNCERTAINTIES REGARDING UPSTREAM CONVECTION AND IMPACTS ON
INSTABILITY FOR THE LOCAL AREA ALONG WITH WHAT SHOULD BE MORE
MARGINAL DEEP LAYER SHEAR PROFILES FOR THIS PERIOD. NO SIGNIFICANT
CHANGES MADE TO VERY WARM TEMPERATURES IN ADVANCE OF THE FRONT
THURSDAY AFTERNOON WITH HIGHS IN THE MID TO UPPER 80S.
ON SATURDAY...ELONGATED SFC RIDGE AXIS TO BUILD INTO GREAT LAKES
REGION BEHIND THIS BOUNDARY...WITH SLIGHTLY MORE STABLE CONDITIONS.
PRECIP CHANCES ARE BECOMING MORE MUDDLED WITH BETTER ISENTROPIC
UPGLIDE OVER BOUNDARY POSSIBLY REMAINING JUST WEST OF THE AREA
ACROSS MID MS RVR VALLEY. CANNOT DISCOUNT ISOLD/SCT SHRA/TSRA
HOWEVER DUE TO PERSISTENT ELEVATED INSTABILITY. PERHAPS A SLIGHTLY
BETTER CHANCE FOR LATE SUNDAY/SUNDAY EVENING WHEN MID LEVEL RIDGE
IS EXPECTED TO SHIFT SLIGHTLY EASTWARD ACROSS CENTRAL CONUS IN
RESPONSE TO NEXT EASTERN PACIFIC WAVE MOVING ACROSS THE NORTHERN
ROCKIES. HOWEVER...BY LATE WEEKEND/EARLY NEXT WEEK MODEL
DETERMINISTIC/ENSEMBLE SPREADS BECOME MUCH MORE PRONOUNCED WITH
THIS NEXT PACIFIC WAVE. ALSO SIGNIFICANT VARIABILITY EXISTS WITH
EASTERN CANADIAN TROUGH THAT WILL IMPACT TRACK OF UPSTREAM PACIFIC
SYSTEM. GIVEN THESE UNCERTAINTIES...HAVE LOWERED CR ALLBLEND LOW
POPS TO BELOW MENTIONABLE LEVELS AND WILL KEEP MON/TUE DRY AT THIS
TIME.
&&
.AVIATION...
MESOSCALE CONVECTIVE VORTEX ACROSS IL TO MOVE NORTHEAST. ASSOCIATED
LINE OF SHOWERS AND THUNDERSTORMS TO MOVE THROUGH TAF SITES THIS
AFTERNOON. HI RES MODEL DATA WANTS TO DEVELOP ADDITIONAL
PRECIPITATION JUST SOUTH OF VORT TRACK THIS EVENING. THIS REMAINS
UNCERTAIN BUT THIS GUIDANCE HAS DONE WELL THIS MORNING WITH CURRENT
COMPLEX. HAVE LINGERED SHOWERS AT TAF SITES WITH BETTER CHANCES AT
KSBN WHICH IS CLOSER TO UPPER LEVEL SYSTEM. UNCERTAINTY GROWS
OVERNIGHT INTO WEDNESDAY AS UPSTREAM CONVECTIVE COMPLEX LIKELY TO
DEVELOP AND COULD BRUSH THE AREA WEDNESDAY MORNING. TOO MUCH
UNCERTAINTY TO ADD TO TAFS BUT WILL BE WATCHED FOR LATER ISSUANCES.
CONVECTION POSSIBLE AGAIN WED AFTERNOON JUST BEYOND THIS VALID
PERIOD WITH RESIDUAL BOUNDARIES AND UNSTABLE ATMOSPHERE DEVELOPING.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...LASHLEY
LONG TERM...MARSILI
AVIATION...LASHLEY
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
125 PM EDT TUE MAY 1 2012
.AVIATION...
MESOSCALE CONVECTIVE VORTEX ACROSS IL TO MOVE NORTHEAST. ASSOCIATED
LINE OF SHOWERS AND THUNDERSTORMS TO MOVE THROUGH TAF SITES THIS
AFTERNOON. HI RES MODEL DATA WANTS TO DEVELOP ADDITIONAL
PRECIPITATION JUST SOUTH OF VORT TRACK THIS EVENING. THIS REMAINS
UNCERTAIN BUT THIS GUIDANCE HAS DONE WELL THIS MORNING WITH CURRENT
COMPLEX. HAVE LINGERED SHOWERS AT TAF SITES WITH BETTER CHANCES AT
KSBN WHICH IS CLOSER TO UPPER LEVEL SYSTEM. UNCERTAINTY GROWS
OVERNIGHT INTO WEDNESDAY AS UPSTREAM CONVECTIVE COMPLEX LIKELY TO
DEVELOP AND COULD BRUSH THE AREA WEDNESDAY MORNING. TOO MUCH
UNCERTAINTY TO ADD TO TAFS BUT WILL BE WATCHED FOR LATER ISSUANCES.
CONVECTION POSSIBLE AGAIN WED AFTERNOON JUST BEYOND THIS VALID
PERIOD WITH RESIDUAL BOUNDARIES AND UNSTABLE ATMOSPHERE DEVELOPING.
&&
.UPDATE...
MAJOR REVISIONS BEING MADE TO SHORT TERM GRIDS AS STRONG MCV IN
NORTHEAST MO CONTINUES TO DRIVE AREA OF THUNDERSTORMS IN IL. THIS
FEATURE TO CONTINUE A NORTHEAST MOVEMENT AND WITH MODEST ELEVATED
INSTABILITY AND STRONG SHEAR ALONG WITH INCREASING THETA E SHOULD BE
ABLE TO SUSTAIN PRECIPITATION ACROSS THE AREA THIS AFTERNOON.
WORKING ON INCREASING POPS TO CATEGORICAL THROUGH THE AFTERNOON FROM
SOUTHWEST TO NORTHEAST ALONG WITH LOWERING TEMPS GIVEN INCREASED
CLOUD COVER AND RAIN. 12Z NAM12 SHOWING STRONG SHEAR ASSOCIATED WITH
THIS FEATURE AS 0-6KM VALUES IN EXCESS OF 50 KNOTS. INSTABILITY WILL
BE LIMITING FACTOR FOR SEVERE WITH COOLER SURFACE TEMPS NO NOT
EXPECTING WIDESPREAD SEVERE BUT CANNOT RULE OUT ISOLATED STRONG
STORMS IF STRONG UPDRAFTS CAN DEVELOP...ESPECIALLY NEAR WARM FRONT
ACROSS SOUTHERN AREAS. RELIED ON HRRR FOR TIMING POPS AS IT SEEMS TO
HAVE BEST HANDLE ON CONVECTION. UPDATE OUT SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 430 AM EDT TUE MAY 1 2012/
SHORT TERM...
TODAY THROUGH WEDNESDAY NIGHT...SOME LIGHT FOG WAS REMAINING EARLY
THIS MORNING UNDER LOW CLOUD CANOPY. A DISTINCT LOW CLOUD
CLEARING LINE WAS APPROACHING THE AREA FROM THE WEST...BUT AT THE
SAME TIME...HIGH CLOUD DEBRIS FROM UPSTREAM STORMS WAS SPREADING
OVER THE FCST AREA. HAVE REMOVED AREAS OF FOG THIS MORNING.
VISIBILITIES ARE EXPECTED TO REMAIN 2 MILES OR MORE. AN UPPER
LEVEL TROF WILL MOVE ACROSS THE MID MISSISSIPPI VALLEY TODAY AND
MOVE INTO THE WESTERN GREAT LAKES REGION TONIGHT. THERE IS SUPPORT
FOR STRONGER STORMS WITH THIS SYSTEM GIVEN FAVORABLE BULK SHEAR
AND SIZABLE CAPES. BLENDED THE SPECTRAL MODELS FOR A COMMON
SOLUTION THAT SUPPORTS TIMING OF THIS SYSTEM ARRIVING TONIGHT. HAVE
INCREASED STORM CHANCES TO LIKELY. THE FRONT WILL CONTINUE TO LIFE
NORTH...WITH THE BULK OF STORMS STAYING NORTH OF THE FORECAST
AREA WEDNESDAY. LEFT A CHANCE FOR STORMS OVER MAINLY MICHIGAN
COUNTIES GIVEN THE CHANCE FOR A STORM TO DEVELOP ON AN OUTFLOW
BOUNDARY ON WEDNESDAY. OTHERWISE...TEMPERATURES SHOULD BE WARMER
WEDNESDAY WITH HIGHS IN THE MID 80S...SUPPORTED BY THE 00Z MEX
MOS.
LONG TERM...
RECD HEAT XPCD TO START THIS PD ON THU AS CRUX OF BROAD UPR RIDGE
BLDS ACRS THE SERN US IN RESPONSE TO AMPLIFYING UPR TROUGH OVR THE
PACNW. ACTIVE FNTL ZONE XPCD INBTWN ON NRN EDGE OF VRY UNSTABLE WARM
SECTOR. SPATIAL DETAILS STILL UNCERTAIN WRT CONVN THU AFTN/THU NIGHT
HWVR GENERAL LEAD HERE IS TWD CONV AUGMENTATION OF PREDICTED SFC
BNDRY POSITION IN SWRLY FLW ALOFT SWD OF SPECTRAL GUIDANCE
POSITIONING OF TRUE SYNOPTIC BNDRY. THUS HELD VERY CLOSE W/PRIOR POP
GUIDANCE ALTHOUGH DID DROP MENTION OF MUCH OF THU DAYTIME PD AS LL
CAPPING INVERSION SHLD BE WELL DVLPD BY THU AM. OTHERWISE STG MIXING
DURING THE DAY WITHIN ZONE OF SIG HGT RISES ALOFT AND INTENSE LL
THERMAL RIDGE PORTEND 90S PSBL IN SOME SPOTS.
BEYOND THAT...GENERAL AGREEMENT AMG 00Z MED RANGE GUIDANCE POINTS TO
A CONSENSUS OF BROAD NRN STREAM TROUGHING SLOWLY PROGRESSING EWD
THROUGH THE END OF THE PD. THIS ALLUDES TO AN ACTUAL FROPA TWD SAT
W/SUCCESSIVE WAVE ADJUSTMENT ALG COMPOSITED OUTFLW STEMMING FM DAILY
PERIOD CONVN ACRS THE PLAINS/MIDWEST A WILDCARD AS TO ACTUAL
EFFECTIVE SFC BNDRY PLACEMENT. THUS WILL GENERALLY TOE THE LINE
W/DAILY POPS DYS4-5. HWVR DOWNSTREAM BLOCKING RIDGE DEPICTED OVR THE
ATL LENDS CREDENCE TWD OP GFS SOLUTION OF FURTHER AMPLIFICATION ACRS
THE CONUS HEADING THROUGH THE WEEKEND AND COOLING TO NEAR SEASONABLE
TEMPS BEGINNING IN DY6 (SUN).
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...SKIPPER
LONG TERM...T
AVIATION...LASHLEY
UPDATE...LASHLEY
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1113 AM EDT TUE MAY 1 2012
.UPDATE...
MAJOR REVISIONS BEING MADE TO SHORT TERM GRIDS AS STRONG MCV IN
NORTHEAST MO CONTINUES TO DRIVE AREA OF THUNDERSTORMS IN IL. THIS
FEATURE TO CONTINUE A NORTHEAST MOVEMENT AND WITH MODEST ELEVATED
INSTABILITY AND STRONG SHEAR ALONG WITH INCREASING THETA E SHOULD BE
ABLE TO SUSTAIN PRECIPITATION ACROSS THE AREA THIS AFTERNOON.
WORKING ON INCREASING POPS TO CATEGORICAL THROUGH THE AFTERNOON FROM
SOUTHWEST TO NORTHEAST ALONG WITH LOWERING TEMPS GIVEN INCREASED
CLOUD COVER AND RAIN. 12Z NAM12 SHOWING STRONG SHEAR ASSOCIATED WITH
THIS FEATURE AS 0-6KM VALUES IN EXCESS OF 50 KNOTS. INSTABILITY WILL
BE LIMITING FACTOR FOR SEVERE WITH COOLER SURFACE TEMPS NO NOT
EXPECTING WIDESPREAD SEVERE BUT CANNOT RULE OUT ISOLATED STRONG
STORMS IF STRONG UPDRAFTS CAN DEVELOP...ESPECIALLY NEAR WARM FRONT
ACROSS SOUTHERN AREAS. RELIED ON HRRR FOR TIMING POPS AS IT SEEMS TO
HAVE BEST HANDLE ON CONVECTION. UPDATE OUT SHORTLY.
&&
.AVIATION...
12Z TAFS...FRONTAL BOUNDARY FROM SOUTHERN ILLINOIS INTO SOUTHERN
INDIANA WILL BEGIN TO RETREAT NORTHWARD AS A WARM FRONT TODAY.
SHALLOW LOW LEVEL MOISTURE...AND WEAK WINDS HAVE RESULTED IN
WIDESPREAD FOG AND STRATUS WITH IFR CONDITIONS BEING REPORTED.
CONDITIONS EXPECTED TO IMPROVE TOWARD 15Z AS DRIER LOW LEVELS
BEGIN TO MIX TO THE SFC. A THUNDERSTORM COMPLEX EXITING OUT OF
MISSOURI WILL ENCOUNTER A MORE UNFAVORABLE ENVIRONMENT IN TERMS OF
MORE LIMITED INSTABILITY. HOWEVER...SOME INCREASE IN INSTABILITY
EXPECTED BY MID TO LATE AFTERNOON MAINLY AT KFWA AS WEAK LOW LEVEL
JET AHEAD OF THIS APPROACHING CONVECTIVE SYSTEM TRANSPORTS BETTER
LOW LEVEL MOISTURE NORTHWARD. DID ADD TEMPO GROUP FOR SHRA AT
KFWA...WITH SOME POSSIBILITY THAT THUNDER MENTION MAY NEED TO BE
ADDED EVENTUALLY FOR THE LATE AFTERNOON HOURS. VCSH MENTION ALSO
MAINTAINED TONIGHT GIVEN LOW LEVEL BOUNDARY WILL LIKELY BE
APPROACHING THE LOCAL AREA.
&&
.PREV DISCUSSION... /ISSUED 430 AM EDT TUE MAY 1 2012/
SHORT TERM...
TODAY THROUGH WEDNESDAY NIGHT...SOME LIGHT FOG WAS REMAINING EARLY
THIS MORNING UNDER LOW CLOUD CANOPY. A DISTINCT LOW CLOUD
CLEARING LINE WAS APPROACHING THE AREA FROM THE WEST...BUT AT THE
SAME TIME...HIGH CLOUD DEBRIS FROM UPSTREAM STORMS WAS SPREADING
OVER THE FCST AREA. HAVE REMOVED AREAS OF FOG THIS MORNING.
VISIBILITIES ARE EXPECTED TO REMAIN 2 MILES OR MORE. AN UPPER
LEVEL TROF WILL MOVE ACROSS THE MID MISSISSIPPI VALLEY TODAY AND
MOVE INTO THE WESTERN GREAT LAKES REGION TONIGHT. THERE IS SUPPORT
FOR STRONGER STORMS WITH THIS SYSTEM GIVEN FAVORABLE BULK SHEAR
AND SIZABLE CAPES. BLENDED THE SPECTRAL MODELS FOR A COMMON
SOLUTION THAT SUPPORTS TIMING OF THIS SYSTEM ARRIVING TONIGHT. HAVE
INCREASED STORM CHANCES TO LIKELY. THE FRONT WILL CONTINUE TO LIFE
NORTH...WITH THE BULK OF STORMS STAYING NORTH OF THE FORECAST
AREA WEDNESDAY. LEFT A CHANCE FOR STORMS OVER MAINLY MICHIGAN
COUNTIES GIVEN THE CHANCE FOR A STORM TO DEVELOP ON AN OUTFLOW
BOUNDARY ON WEDNESDAY. OTHERWISE...TEMPERATURES SHOULD BE WARMER
WEDNESDAY WITH HIGHS IN THE MID 80S...SUPPORTED BY THE 00Z MEX
MOS.
LONG TERM...
RECD HEAT XPCD TO START THIS PD ON THU AS CRUX OF BROAD UPR RIDGE
BLDS ACRS THE SERN US IN RESPONSE TO AMPLIFYING UPR TROUGH OVR THE
PACNW. ACTIVE FNTL ZONE XPCD INBTWN ON NRN EDGE OF VRY UNSTABLE WARM
SECTOR. SPATIAL DETAILS STILL UNCERTAIN WRT CONVN THU AFTN/THU NIGHT
HWVR GENERAL LEAD HERE IS TWD CONV AUGMENTATION OF PREDICTED SFC
BNDRY POSITION IN SWRLY FLW ALOFT SWD OF SPECTRAL GUIDANCE
POSITIONING OF TRUE SYNOPTIC BNDRY. THUS HELD VERY CLOSE W/PRIOR POP
GUIDANCE ALTHOUGH DID DROP MENTION OF MUCH OF THU DAYTIME PD AS LL
CAPPING INVERSION SHLD BE WELL DVLPD BY THU AM. OTHERWISE STG MIXING
DURING THE DAY WITHIN ZONE OF SIG HGT RISES ALOFT AND INTENSE LL
THERMAL RIDGE PORTEND 90S PSBL IN SOME SPOTS.
BEYOND THAT...GENERAL AGREEMENT AMG 00Z MED RANGE GUIDANCE POINTS TO
A CONSENSUS OF BROAD NRN STREAM TROUGHING SLOWLY PROGRESSING EWD
THROUGH THE END OF THE PD. THIS ALLUDES TO AN ACTUAL FROPA TWD SAT
W/SUCCESSIVE WAVE ADJUSTMENT ALG COMPOSITED OUTFLW STEMMING FM DAILY
PERIOD CONVN ACRS THE PLAINS/MIDWEST A WILDCARD AS TO ACTUAL
EFFECTIVE SFC BNDRY PLACEMENT. THUS WILL GENERALLY TOE THE LINE
W/DAILY POPS DYS4-5. HWVR DOWNSTREAM BLOCKING RIDGE DEPICTED OVR THE
ATL LENDS CREDENCE TWD OP GFS SOLUTION OF FURTHER AMPLIFICATION ACRS
THE CONUS HEADING THROUGH THE WEEKEND AND COOLING TO NEAR SEASONABLE
TEMPS BEGINNING IN DY6 (SUN).
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...SKIPPER
LONG TERM...T
AVIATION...MARSILI
UPDATE...LASHLEY
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
715 PM CDT WED MAY 2 2012
.UPDATE...
PREVIOUS THOUGHTS OF CONVECTION DEVELOPING ACROSS NORTHERN IOWA IN
THE LATE AFTERNOON/EARLY EVENING HAVE NOT OCCURRED...WITH DECENT CAP
STILL IN PLACE ALOFT VIA DVN 00Z SOUNDING DUE TO STRATUS/LOW CLOUD
COVER LINGERING MUCH OF THE DAY. THEREFORE HAVE TAPERED POPS DOWN
FOR THE EARLY EVENING HOURS AT THIS TIME. A FEW CELLS ARE TRYING TO
GO UP ON SFC BOUNDARY SITUATED ACROSS ERN NE/SE SD INTO SRN MN.
THESE CELLS HAVING TOUGHER TIME SUSTAINING THEMSELVES AS WELL.
THEREFORE FOCUS ON THUNDERSTORM DEVELOPMENT TURNS TO LATER TONIGHT
WITH MID LEVEL WAVE APPROACHES FROM THE WEST AND LLJ INCREASES AND
LOW LEVEL MOISTURE TRANSPORT BECOMES ORIENTED RIGHT INTO CENTRAL
IOWA. HRRR MODEL SUGGESTING STORMS PUSHING INTO CENTRAL IOWA AROUND
MIDNIGHT OR LATER AT THIS TIME...SO HAVE TRENDED GREATEST POPS
ACROSS THE CWA FOR THE LATE NIGHT HOURS.
.SHORT TERM /TONIGHT/...
SEVERAL CONCERNS OVERNIGHT AS ACTIVE WSW FLOW ALOFT CONTINUES.
OUTFLOW FROM THE MORNING CONVECTION HAD CLEARED WELL SOUTH OF THE
BORDER EARLIER TODAY AND THERE HAS BEEN GRADUAL RECOVER THROUGH THE
AFTERNOON AS SOUTHERLY WINDS HAVE INCREASED ALONG WITH MOISTURE.
CAPES HAVE STEADILY INCREASED WITH 100MB MIXED LAYER OF 2000-3000
J/KG ACROSS WESTERN AND NORTHERN IOWA. HOWEVER...18Z SOUNDING AT
KOAX HAS INDICATED SOME CAPPING ALONG WITH A GENERALLY DIVERGENT
SURFACE FLOW IN NORTHERN IOWA. THESE PARTICULAR FEATURES ARE LIKELY
INHIBITING CONVECTION AT THIS POINT BUT THIS SHOULD CHANGE BY THIS
EVENING WITH THE APPROACH OF A SHORTWAVE IN THE PLAINS. MODELS HAVE
BEEN INDICATING CONVECTION IN NORTH CENTRAL AND NORTHEAST IOWA THIS
EVENING WHERE LOW LEVEL JET/FLOW WILL BE DIRECTED. THIS AREA HAS
VERY HIGH PWATS AND WITH THIS PERSISTENT LOW LEVEL FLOW DIRECTED IN
THAT LOCATION AND FLASH FLOOD GUIDANCE VALUES OF ONE TO ONE AND A
HALF INCHES...HAVE OPTED FOR A FLASH FLOOD WATCH IN FAR NORTHEAST.
ELSEWHERE...CONVECTION EXPECTED IN THE NORTH THIS EVENING WHERE CAP
IS WEAKEST WITH ADDITIONAL CONVECTION IN NEBRASKA HEADING TOWARD
CENTRAL AND SOUTHERN IOWA LATE TONIGHT INTO EARLY THURSDAY MORNING.
THIS CONVECTION WILL HAVE THE THREAT FOR SEVERE STRAIGHT LINE WINDS
ALONG WITH LARGE HAIL AND A ISOLATED TORNADOES AS IT PROGRESSES
RAPIDLY EASTWARD OVERNIGHT.
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
COMPLICATED LONG TERM FORECAST...WITH LOW CONFIDENCE. ANTICIPATE
OVERNIGHT MCS TO BE LINGERING ACROSS THE NORTH AND EAST FOR
BEGINNING OF TOMORROW BEFORE PUSHING OUT OF CWA. CONDITIONS WILL
IMPROVE THROUGH THE DAY...BUT WITH LINGERING FRONTAL BOUNDARY ACROSS
SOUTHERN IOWA BY THURSDAY AFTERNOON...EXPECT TO SEE AFTERNOON
DEVELOPMENT. BUT AGAIN ANTICIPATE BEST CHANCES FOR PRECIPITATION TO
BE ANOTHER ROUND OF OVERNIGHT MCS CONVECTION...FOCUSED ACROSS
SOUTHERN IOWA. PWAT VALUES ARE HIGH...WITH PLENTY OF MOISTURE
AVAILABLE COULD SEE POTENTIAL FOR LOCALIZED AREAS OF HEAVY RAIN
AGAIN OVERNIGHT THURSDAY NIGHT...AGAIN HIGHEST LIKELIHOOD APPEARS TO
BE ACROSS SOUTHERN IOWA. OVERNIGHT PRECIPITATION COULD LINGER INTO
EARLY FRIDAY BEFORE AGAIN QUICKLY PUSHING OUT OF THE CWA. HAVE LEFT
SLIGHT CHANCE POPS FOR FRIDAY AFTERNOON WITH POTENTIAL FOR AFTERNOON
DEVELOPMENT WITH ANOTHER APPROACHING FRONTAL SYSTEM...BUT AGAIN
APPEARS MAIN PRECIP CHANCES WILL BE OVERNIGHT.
TEMPERATURES BECOME A BIT TRICKY FOR FRIDAY AND SATURDAY. WAA AHEAD
OF APPROACHING FRONTAL SYSTEM IS STRONG FOR FRIDAY WITH GOOD MIXING
POSSIBLE FRIDAY. IF MIXING IS FULLY REALIZED...OR SKIES CLEAR FOR
LONG ENOUGH COULD EASILY SEE TEMPERATURES POP UP INTO THE UPPER 80S
FOR MUCH OF THE CENTRAL AND SOUTHERN PORTIONS OF THE CWA. HAVE
INCREASED TEMPERATURES FOR FRIDAY AND SATURDAY...BUT MAY STILL HAVE
BEEN TOO COOL...ESPECIALLY FOR FRIDAY. TIMING OF FRONTAL BOUNDARY
WILL HAVE IMPACT ON TEMPS FOR SATURDAY...WITH LITTLE MODEL AGREEMENT
ON PLACING OF FRONT HAVE TRENDED UPWARDS WITH TEMPS.
ACTIVE PATTERN CONTINUES FOR REMAINDER OF EXTENDED WITH AREA OF LOW
PRESSURE EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS/SOUTHERN CANADA
FOR THE END OF EXTENDED. ASSOCIATED FRONTAL BOUNDARYS WILL BRING
CHANCES FOR PRECIPITATION THROUGH THE WEEKEND...WITH LINGERING
PRECIPITATION INTO EARLY NEXT WEEK.
&&
.AVIATION...03/00Z
LOWER TO MID LEVEL STRATUS AND CU CONTINUE ACROSS THE CWA...AND
EXPECT TO LINGER THROUGH THE EVENING. A FEW LIGHT SHOWERS ACROSS FAR
NORTH IN AREA WHERE PREVIOUSLY THOUGHT THERE WOULD BE SOME
THUNDERSTORM DEVELOPMENT BY THIS TIME. CLOUD COVER HAS HINDERED THIS
DEVELOPMENT THUS FAR...AND THEREFORE NOW EXPECT GREATER CHANCES FOR
THUNDERSTORMS TO BE PUSHED OFF UNTIL LATER TONIGHT. THEREFORE PUSHED
BACK START TIME ON -TSRA UNTIL AFTER 06Z FOR THE MOST PART WHEN AN
UPPER LEVEL DISTURBANCE WILL MOVE CLOSER TO THE REGION AND LOWER
LEVEL WINDS PICK UP CREATING A BETTER ENVIRONMENT FOR THUNDERSTORM
DEVELOPMENT. ALSO HAVE LEFT IN MENTION OF BKN025-035 CLOUD DECK
THROUGH THE DAY THURSDAY...AS EXPECT IT TO BE SIMILAR TO TODAY WITH
LINGERING LOW CLOUDS. THIS WOULD PUSH DEVELOPMENT OF THUNDER ON
THURSDAY TO JUST BEYOND THE CURRENT TAF PERIOD...SO HAVE LEFT OUT OF
THE TAF AT THIS TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH THURSDAY
MORNING FOR BLACK HAWK-BREMER-BUTLER-CERRO GORDO-FRANKLIN-GRUNDY-
HARDIN.
&&
$$
SHORT TERM...COGIL
LONG TERM...AWB
AVIATION...MJB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1013 AM CDT TUE MAY 1 2012
.UPDATE...
AN UPDATE WAS JUST SENT TO LOW TEMPS FOR TODAY IN NORTHWEST IL AND
ADJACENT AREAS OF EASTERN IA AND TO LOW POPS TODAY MAINLY IN EAST
CENTRAL IA.
AREA OF SHRA CONTINUES TO LIFT NORTH BUT CONTINUES TO SHOW A
STEADY WEAKENING TREND. THIS TREND SHOULD CONTINUE AS IT MOVES
INTO A COOLER/DRIER AIRMASS OVER NORTHERN IL AND IS VERIFIED BY
LATEST HRRR RUNS. LOW POPS MAINLY NORTH OF HIGHWAY 30 IN EASTERN
IA TO CHANCE OR SLIGHT CHANCE CATEGORIES.
THE SURFACE WARM FRONT IS STILL SOUTH OF THE CWFA OVER CENTRAL MO
BUT IS FORECAST TO MOVE NORTH TODAY. THE FRONT HAS A LONG WAY TO
GO TO REACH THE NORTHERN PART OF THE CWFA BUT THERE COULD BE A
JUMP TO THE NORTH LATE THIS MORNING OR EARLY THIS AFTERNOON AS THE
WARM SECTOR HEATS UP AND MIXES OUT. THE 12Z NAM WAS USED FOR THE
FRONTAL MOVEMENT THIS AFTERNOON...WHICH PLACES THE WARM FRONT OVER
THE NORTHEAST CWFA BY LATE AFTERNOON. LOWERED TEMPS INTO THE UPPER
60S IN THE NORTHEAST. ALTHOUGH DUE TO THE LATE DAY ARRIVAL TEMPS
IN THIS AREA WILL LIKELY STAY IN THE 50S UNTIL THE FRONT ARRIVES LATE
THIS AFTERNOON.
CHANCE POPS FOR TSRA WERE MAINTAINED THROUGH THE AFTERNOON ALONG
AND NORTH WARM FRONT. SOUTH OF THE FRONT SHORT RANGE MODEL GUIDANCE
WAS SHOWING THE WARM SECTOR DESTABILIZING AND UNCAPPED BY MID
AFTERNOON. ALTHOUGH THERE IS NO APPARENT TRIGGER THIS
AFTERNOON...FELT MAINTAINING SOME SLIGHT CHANCE POPS WAS WARRANTED.
&&
.PREV DISCUSSION... /ISSUED 647 AM CDT TUE MAY 1 2012/
AVIATION...
GENERALLY VFR CONDITIONS WITH PATCHY SHALLOW FOG UNTIL 14Z AT DBQ
AND CID TERMINALS. CLOUDS TO INCREASE WITH SHRA AND ISOLATED TSRA
LIKELY AT BRL AND MLI BY 14Z WITH PERIODS OF MVFR CONDITIONS
SUGGESTED WITH CLOUD BASES OF 1-3K AGL BETWEEN 14-20Z IN LIGHT TO
MODERATE RAIN AND POSSIBLY AN EMBEDDED THUNDERSTORM. SE WINDS OF
10 TO 20+ MPH BY AFTERNOON ALL TERMINALS. PARTIAL CLEARING WITH
VFR CONDITIONS BY 21Z. TONIGHT...CHANCE FOR NOCTURNAL STORMS TO
IMPACT CID AND DBQ TERMINALS AFTER 06Z AS WARM FRONTAL BOUNDARY
BECOMES ACTIVE. NICHOLS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
647 AM CDT TUE MAY 1 2012
.AVIATION...
GENERALLY VFR CONDITIONS WITH PATCHY SHALLOW FOG UNTIL 14Z AT DBQ
AND CID TERMINALS. CLOUDS TO INCREASE WITH SHRA AND ISOLATED TSRA
LIKELY AT BRL AND MLI BY 14Z WITH PERIODS OF MVFR CONDITIONS
SUGGESTED WITH CLOUD BASES OF 1-3K AGL BETWEEN 14-20Z IN LIGHT TO
MODERATE RAIN AND POSSIBLY AN EMBEDDED THUNDERSTORM. SE WINDS OF
10 TO 20+ MPH BY AFTERNOON ALL TERMINALS. PARTIAL CLEARING WITH
VFR CONDITIONS BY 21Z. TONIGHT...CHANCE FOR NOCTURNAL STORMS TO
IMPACT CID AND DBQ TERMINALS AFTER 06Z AS WARM FRONTAL BOUNDARY
BECOMES ACTIVE. NICHOLS
&&
.PREV DISCUSSION... /ISSUED 330 AM CDT TUE MAY 1 2012/
SYNOPSIS...
ANALYSIS AND NOWCAST TOOLS INDICATE VIGOROUS SHORT WAVE IN WESTERN
MISSOURI TO OCCLUDE AND MOVE ACROSS SE 1/2 TO 2/3 PORTIONS OF THE
AREA TODAY. THIS DYNAMIC SYSTEM IS POORLY HANDLED BY MOST SOLUTIONS
WITH HI-RES ECMWF AND LATEST 06Z RUC TRENDING CORRECTLY. AREA
TEMPERATURES HAVE CRASHED AT 2 AM INTO THE 40S OVER THE REGION WITH
39F AT FREEPORT. THIS BAROCLINICITY WILL ENHANCE MISSOURI SYSTEM FOR
LOTS OF CLOUDS AND RAIN SHOWERS AND SOME EMBEDDED THUNDER.
COMMENT...INITIALIZATION AND VERIFICATION COMBINED WITH RUN TO RUN
CONTINUITY SUPPORTS STRONGLY USE OF HI-RES ECMWF NEXT 24 HOURS.
BESIDES RESULTING IN MAJOR CHANGES TO FORECAST OF HIGHER POPS (MUCH)
AND LOWER TEMPERATURES (MUCH). THIS PUTS AREA IN PRECARIOUS POSITION
FOR STRONG CONVECTION TONIGHT WITH LOW LEVEL JET SUGGESTING
TRAINING OF STORMS WITH SOME SEVERE AND POSSIBLY HEAVY TO LOCALLY
VERY HEAVY RAINFALL.
SHORT TERM...TODAY AND TONIGHT...
TODAY...LOWERED MAX TEMPERATURES BY 5+ DEGREES ACROSS AREA WITH
NORTHERN PORTIONS POSSIBLY NOT REACHING 70F DUE TO CLOUDS AND
PRECIPITATION. POPS HAVE RAISED TO HIGH LIKELY SOUTH AND CHANCE NORTH
BUT TRENDS SUGGEST GOING EVEN HIGHER. WIDESPREAD .1 TO 25+ INCHES
SUGGESTED SOUTH OF I-80 WITH LOCALLY UP TO .5 INCHES POSSIBLE
SUGGESTED ALONG AND SOUTH OF HIGHWAY 34. THE STRONG BAROCLINIC
GRADIENT MAY ALSO RESULT IN LOW CLOUDS INTO THE PM HOURS. IF SYSTEM
STRONG ENOUGH...COULD SEE STRONGER WINDS WITH GUSTS OVER 30+ MPH IN
MODEST INTERNAL GRAVITY WAVES WITH LATENT HEAT RELEASE.
TONIGHT...WARM FRONT TO MOVE NORTH TONIGHT WITH UPPER DIFFLUENCE AND
LOW LEVEL JET SUPPORTING EVENING AND OVERNIGHT CONVECTION TO
BLOSSOM ACROSS AREA BY MIDNIGHT NORTH OF HIGHWAY 34. LOCAL HEAVY
RAIN TOOLS SUGGESTS TRAINING OF STORMS POSSIBLE WITH PW/S 1.25 TO
1.5+ INCHES WITH LOW LEVEL JET OF 40-45 KTS FOR AREAS OF 2 TO
POSSIBLY NEAR 3 INCHES FOR LATER SHIFTS. HAVE KEPT POPS LOWER DUE
TO CONCERN OF WHERE STORMS FIRE BUT SOME SEVERE STORMS AND LOCALLY
HEAVY RAINFALL ARE FAVORED ATTM. LOCAL TECHNIQUES SUGGEST LARGE
HAIL UP TO GOLF BALLS OR 1.75 INCHES IN DIAMETER WITH STRAIGHT LINE
WINDS OF 50+ MPH TO NEAR SEVERE THE SECONDARY RISK. CHANCES OF
STORMS AND HEAVY RAIN DECREASE RAPIDLY SOUTH OF HIGHWAY 34. MINS
SUGGESTED TO BE IN THE MIDDLE TO UPPER 60S. NICHOLS
LONG TERM...WEDNESDAY THROUGH MONDAY...
WET AND UNSETTLED WEATHER WILL PREVAIL OVER MUCH OF THE AREA
THROUGHOUT. CYCLONIC SW UPPER LEVEL FLOW AND NEARLY PARALLEL
STATIONARY FRONT SETTING UP FROM NEB NORTHEAST THROUGH MN AND WI
WILL PLACE THE LOCAL FORECAST AREA INTO THE MUCH WARMER...HUMID GULF
AIRMASS THAT HAS BEEN POISED TO THE SOUTH ACROSS THE SOUTHERN PLAINS
AND LOWER MS VALLEY THE PAST SEVERAL DAYS...THROUGH AT LEAST FRIDAY.
PERIODIC MID LEVEL SHORTWAVES ARE EXPECTED TO TRIGGER
THUNDERSTORM COMPLEXES ALONG THIS BOUNDARY TO THE NORTH...WHICH MAY
MIGRATE SOUTHEAST INTO AT LEAST THE NORTHERN HALF OF THE FORECAST
AREA. RESULTING OUTFLOW BOUNDARIES MAY THEN RESULT IN A SECONDARY
FRONT FURTHER SETTING UP FURTHER SOUTH OVER THE LOCAL FORECAST
AREA...THAT COULD LEAD TO HEAVY RAINFALL...AS ADVERTISED BY THE LAST
COUPLE ECMWF RUNS. BESIDES THE THREAT OF HEAVY RAINFALL...WILL ALSO
HAVE THE POTENTIAL FOR SEVERAL ROUNDS OF SEVERE WEATHER OVER
PORTIONS OF THE FORECAST AREA DUE TO THE VERY MOIST...UNSTABLE
AIRMASS AND PERIODS OF WEAK UPPER FORCING THAT ENHANCE DEEP SHEAR.
WED INTO WED NIGHT...WILL KEEP A TREND OF HIGHER CHANCE POPS NORTH
AND SLIGHT TO LOW CHANCE POPS IN THE SOUTH WHERE WARMER TEMPERATURES
ALOFT MAY EFFECTIVELY CAP CONVECTION THROUGH MUCH OF THE DAY...ONCE
THE NOCTURNAL CONVECTION DISSIPATES. SURFACE TEMPERATURES SHOULD
EASILY REACH INTO THE UPPER 70S TO LOWER 80S...WHILE DEWPOINTS CLIMB
INTO THE 60S. HAVE KEPT TEMPERATURES TRENDED ON THE CONSERVATIVE
SIDE BASED ON LOW CONFIDENCE THAT CLOUD COVER WILL CLEAR. BUILDING
INSTABILITY...ESPECIALLY IF SKIES DO CLEAR...WOULD PUSH SURFACE
BASED CAPES ABOVE 2000 J/KG. THIS...ALONG WITH A REDEVELOPING LOW
LEVEL JET BY OVERNIGHT AND A POSSIBLE SHORTWAVE BRUSHING THE
NW...WILL CONTINUE A RISK FOR SEVERE STORMS. SPC HAS A DAY 2 SLIGHT
RISK OVER MOST OF THE AREA...BUT THIS POTENTIAL LOOKS TO BE HIGHER
DURING THE LATTER HALF OF THE PERIOD...FROM LATE WED AFTERNOON INTO
LATE EVENING WITH THE AID OF THE AFOREMENTIONED LOW LEVEL JET AND
UPPER FORCING.
THURSDAY AND FRIDAY...WILL HAVE A CONTINUED POTENTIAL FOR HEAVY RAIN
AND POSSIBLE SEVERE STORMS...THAT WILL BE GREATLY DEPENDENT ON THE
FOCUS OF THE LOW LEVEL JET...WHICH THE ECMWF HAS OVER CENTRAL AND
EASTERN IA. THIS COULD EASILY LEAD TO 48 HOUR RAINFALL TOTALS WELL
OVER 2 INCHES. CONFIDENCE IS NOT HIGH ON DETAILS THIS FAR
OUT...ESPECIALLY GIVEN THE UNKNOWNS WITH CONVECTIVE TRENDS AND MCS
INTERACTIONS. FOR NOW WILL KEEP CHANCE POPS GOING WITH LOW QPF THAT
WOULD NEED TO BE INCREASED IF FORECAST CONFIDENCE INCREASES.
WILL HAVE TO HAVE SOME BREAKS IN THE ACTIVITY TO ALLOW FORECAST
HIGHS IN THE 80S TO BE ACHIEVED. HIGH DEWPOINTS WILL HOLD MINS IN
THE 60S.
FORECAST CONFIDENCE DIMINISHES CONSIDERABLY OVER THE WEEKEND INTO
EARLY NEXT WEEK...AS MEDIUM RANGE MODELS DIVERGE IN THE TIMING
AND PLACEMENT OF A RIDGE BUILDING ALOFT. THIS AFFECTS THE PLACEMENT
OF THE ASSOCIATED SURFACE HIGH...SYNOPTIC BOUNDARY...AND ASSOCIATED
FOCUS FOR RAIN AND THUNDERSTORMS. LATEST FORECAST BASED ON MODEL
BLEND HAS HIGHS COOLING FROM THE 80S SATURDAY...TO 60S BY MONDAY
WITH PRECIPITATION LIKELY BECOMING MORE IN THE FORM OF LIGHT RAIN BY
SUNDAY AND MONDAY WITH MUCH MORE LIMITED POTENTIAL FOR
THUNDERSTORMS.
SHEETS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
330 AM CDT TUE MAY 1 2012
.SYNOPSIS...
ANALYSIS AND NOWCAST TOOLS INDICATE VIGOROUS SHORT WAVE IN WESTERN
MISSOURI TO OCCLUDE AND MOVE ACROSS SE 1/2 TO 2/3 PORTIONS OF THE
AREA TODAY. THIS DYNAMIC SYSTEM IS POORLY HANDLED BY MOST SOLUTIONS
WITH HI-RES ECMWF AND LATEST 06Z RUC TRENDING CORRECTLY. AREA
TEMPERATURES HAVE CRASHED AT 2 AM INTO THE 40S OVER THE REGION WITH
39F AT FREEPORT. THIS BAROCLINICITY WILL ENHANCE MISSOURI SYSTEM FOR
LOTS OF CLOUDS AND RAIN SHOWERS AND SOME EMBEDDED THUNDER.
COMMENT...INITIALIZATION AND VERIFICATION COMBINED WITH RUN TO RUN
CONTINUITY SUPPORTS STRONGLY USE OF HI-RES ECMWF NEXT 24 HOURS.
BESIDES RESULTING IN MAJOR CHANGES TO FORECAST OF HIGHER POPS (MUCH)
AND LOWER TEMPERATURES (MUCH). THIS PUTS AREA IN PRECARIOUS POSITION
FOR STRONG CONVECTION TONIGHT WITH LOW LEVEL JET SUGGESTING
TRAINING OF STORMS WITH SOME SEVERE AND POSSIBLY HEAVY TO LOCALLY
VERY HEAVY RAINFALL.
&&
.SHORT TERM...TODAY AND TONIGHT...
TODAY...LOWERED MAX TEMPERATURES BY 5+ DEGREES ACROSS AREA WITH
NORTHERN PORTIONS POSSIBLY NOT REACHING 70F DUE TO CLOUDS AND
PRECIPITATION. POPS HAVE RAISED TO HIGH LIKELY SOUTH AND CHANCE NORTH
BUT TRENDS SUGGEST GOING EVEN HIGHER. WIDESPREAD .1 TO 25+ INCHES
SUGGESTED SOUTH OF I-80 WITH LOCALLY UP TO .5 INCHES POSSIBLE
SUGGESTED ALONG AND SOUTH OF HIGHWAY 34. THE STRONG BAROCLINIC
GRADIENT MAY ALSO RESULT IN LOW CLOUDS INTO THE PM HOURS. IF SYSTEM
STRONG ENOUGH...COULD SEE STRONGER WINDS WITH GUSTS OVER 30+ MPH IN
MODEST INTERNAL GRAVITY WAVES WITH LATENT HEAT RELEASE.
TONIGHT...WARM FRONT TO MOVE NORTH TONIGHT WITH UPPER DIFFLUENCE AND
LOW LEVEL JET SUPPORTING EVENING AND OVERNIGHT CONVECTION TO
BLOSSOM ACROSS AREA BY MIDNIGHT NORTH OF HIGHWAY 34. LOCAL HEAVY
RAIN TOOLS SUGGESTS TRAINING OF STORMS POSSIBLE WITH PW/S 1.25 TO
1.5+ INCHES WITH LOW LEVEL JET OF 40-45 KTS FOR AREAS OF 2 TO
POSSIBLY NEAR 3 INCHES FOR LATER SHIFTS. HAVE KEPT POPS LOWER DUE
TO CONCERN OF WHERE STORMS FIRE BUT SOME SEVERE STORMS AND LOCALLY
HEAVY RAINFALL ARE FAVORED ATTM. LOCAL TECHNIQUES SUGGEST LARGE
HAIL UP TO GOLF BALLS OR 1.75 INCHES IN DIAMETER WITH STRAIGHT LINE
WINDS OF 50+ MPH TO NEAR SEVERE THE SECONDARY RISK. CHANCES OF
STORMS AND HEAVY RAIN DECREASE RAPIDLY SOUTH OF HIGHWAY 34. MINS
SUGGESTED TO BE IN THE MIDDLE TO UPPER 60S. NICHOLS
.LONG TERM...WEDNESDAY THROUGH MONDAY...
WET AND UNSETTLED WEATHER WILL PREVAIL OVER MUCH OF THE AREA
THROUGHOUT. CYCLONIC SW UPPER LEVEL FLOW AND NEARLY PARALLEL
STATIONARY FRONT SETTING UP FROM NEB NORTHEAST THROUGH MN AND WI
WILL PLACE THE LOCAL FORECAST AREA INTO THE MUCH WARMER...HUMID GULF
AIRMASS THAT HAS BEEN POISED TO THE SOUTH ACROSS THE SOUTHERN PLAINS
AND LOWER MS VALLEY THE PAST SEVERAL DAYS...THROUGH AT LEAST FRIDAY.
PERIODIC MID LEVEL SHORTWAVES ARE EXPECTED TO TRIGGER
THUNDERSTORM COMPLEXES ALONG THIS BOUNDARY TO THE NORTH...WHICH MAY
MIGRATE SOUTHEAST INTO AT LEAST THE NORTHERN HALF OF THE FORECAST
AREA. RESULTING OUTFLOW BOUNDARIES MAY THEN RESULT IN A SECONDARY
FRONT FURTHER SETTING UP FURTHER SOUTH OVER THE LOCAL FORECAST
AREA...THAT COULD LEAD TO HEAVY RAINFALL...AS ADVERTISED BY THE LAST
COUPLE ECMWF RUNS. BESIDES THE THREAT OF HEAVY RAINFALL...WILL ALSO
HAVE THE POTENTIAL FOR SEVERAL ROUNDS OF SEVERE WEATHER OVER
PORTIONS OF THE FORECAST AREA DUE TO THE VERY MOIST...UNSTABLE
AIRMASS AND PERIODS OF WEAK UPPER FORCING THAT ENHANCE DEEP SHEAR.
WED INTO WED NIGHT...WILL KEEP A TREND OF HIGHER CHANCE POPS NORTH
AND SLIGHT TO LOW CHANCE POPS IN THE SOUTH WHERE WARMER TEMPERATURES
ALOFT MAY EFFECTIVELY CAP CONVECTION THROUGH MUCH OF THE DAY...ONCE
THE NOCTURNAL CONVECTION DISSIPATES. SURFACE TEMPERATURES SHOULD
EASILY REACH INTO THE UPPER 70S TO LOWER 80S...WHILE DEWPOINTS CLIMB
INTO THE 60S. HAVE KEPT TEMPERATURES TRENDED ON THE CONSERVATIVE
SIDE BASED ON LOW CONFIDENCE THAT CLOUD COVER WILL CLEAR. BUILDING
INSTABILITY...ESPECIALLY IF SKIES DO CLEAR...WOULD PUSH SURFACE
BASED CAPES ABOVE 2000 J/KG. THIS...ALONG WITH A REDEVELOPING LOW
LEVEL JET BY OVERNIGHT AND A POSSIBLE SHORTWAVE BRUSHING THE
NW...WILL CONTINUE A RISK FOR SEVERE STORMS. SPC HAS A DAY 2 SLIGHT
RISK OVER MOST OF THE AREA...BUT THIS POTENTIAL LOOKS TO BE HIGHER
DURING THE LATTER HALF OF THE PERIOD...FROM LATE WED AFTERNOON INTO
LATE EVENING WITH THE AID OF THE AFOREMENTIONED LOW LEVEL JET AND
UPPER FORCING.
THURSDAY AND FRIDAY...WILL HAVE A CONTINUED POTENTIAL FOR HEAVY RAIN
AND POSSIBLE SEVERE STORMS...THAT WILL BE GREATLY DEPENDENT ON THE
FOCUS OF THE LOW LEVEL JET...WHICH THE ECMWF HAS OVER CENTRAL AND
EASTERN IA. THIS COULD EASILY LEAD TO 48 HOUR RAINFALL TOTALS WELL
OVER 2 INCHES. CONFIDENCE IS NOT HIGH ON DETAILS THIS FAR
OUT...ESPECIALLY GIVEN THE UNKNOWNS WITH CONVECTIVE TRENDS AND MCS
INTERACTIONS. FOR NOW WILL KEEP CHANCE POPS GOING WITH LOW QPF THAT
WOULD NEED TO BE INCREASED IF FORECAST CONFIDENCE INCREASES.
WILL HAVE TO HAVE SOME BREAKS IN THE ACTIVITY TO ALLOW FORECAST
HIGHS IN THE 80S TO BE ACHIEVED. HIGH DEWPOINTS WILL HOLD MINS IN
THE 60S.
FORECAST CONFIDENCE DIMINISHES CONSIDERABLY OVER THE WEEKEND INTO
EARLY NEXT WEEK...AS MEDIUM RANGE MODELS DIVERGE IN THE TIMING
AND PLACEMENT OF A RIDGE BUILDING ALOFT. THIS AFFECTS THE PLACEMENT
OF THE ASSOCIATED SURFACE HIGH...SYNOPTIC BOUNDARY...AND ASSOCIATED
FOCUS FOR RAIN AND THUNDERSTORMS. LATEST FORECAST BASED ON MODEL
BLEND HAS HIGHS COOLING FROM THE 80S SATURDAY...TO 60S BY MONDAY
WITH PRECIPITATION LIKELY BECOMING MORE IN THE FORM OF LIGHT RAIN BY
SUNDAY AND MONDAY WITH MUCH MORE LIMITED POTENTIAL FOR
THUNDERSTORMS.
SHEETS
&&
.AVIATION...
GENERALLY VFR CONDITIONS THROUGH 15Z WITH PATCHY SHALLOW FOG UNTIL
12Z. CLOUDS TO INCREASE WITH SHRA AND ISOLATED TSRA LIKELY AT BRL AND
MLI BY 16Z WITH PERIODS OF MVFR CONDITIONS SUGGESTED WITH CLOUD BASES
OF 1-3K AGL BETWEEN 17-22Z IN LIGHT TO MODERATE RAIN AND POSSIBLY
EMBEDDED THUNDERSTORM. SE WINDS OF 10 TO 20+ MPH BY AFTERNOON ALL
TERMINALS. PARTIAL CLEARING WITH VFR CONDITIONS RETURNING BY 21Z.
TONIGHT...CHANCE FOR NOCTURNAL STORMS TO IMPACT CID AND DBQ TERMINALS
AFTER 06Z AS WARM FRONTAL BOUNDARY BECOMES ACTIVE. NICHOLS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
NICHOLS/SHEETS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
306 PM CDT TUE MAY 1 2012
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 215 PM CDT TUE MAY 1 2012
WE APPEAR TO BE SOMEWHAT CAPPED THIS AFTERNOON...SOMETHING THAT
BARELY SHOWED UP IN THE RUC MODEL SOUNDING DATA. THE HRRR MODEL
CONTINUED TO UPDATE WITH BANDS OF PCPN ASSOCIATED WITH THE
WEAKENING VORT MAX ACROSS MAINLY SRN IL/SWRN IND/NRN KY...
APPARENTLY NOT TAKING THIS INTO ACCOUNT. HOWEVER...RADAR AT THIS
TIME SHOWED WIDELY SCATTERED SHOWERS BUBBLING UP ACROSS SWRN IND.
WE HAVE WARNINGS AND WATCHES JUST TO OUR EAST. SO...THESE
POTENTIAL STORMS DESERVE WATCHING AS THE 50+KT MID LEVEL JET
EXITS OUR REGION OVER THE NEXT HOUR OR TWO. SUSTAINED 15 KT WINDS
ARE EXPECTED TO SUBSIDE TO AOB 10 KTS OVERNIGHT.
WED WILL BE ANOTHER BREEZY DAY UNDER SWRLY FLOW ALOFT AND A MOIST
SRLY FETCH...BUT NO SIGNIFICANT PCPN IS EXPECTED WITH ANY SFC
FEATURES WELL OUT OF THE AREA. THU SHOULD BE SIMILIAR...EXCEPT
THAT POSSIBLY SOME GULF MOISTURE MAY GET TAPPED IN THE AFTERNOON
MAINLY NEAR THE AR/TN BORDER FOR A SHOWER OR TSTM. ABOVE NORMAL
TEMPS WILL CONTINUE.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 215 PM CDT TUE MAY 1 2012
COMPLICATED SYNOPTIC PATTERN ACROSS THE COUNTRY IS RESULTING A LOW
CONFIDENCE FORECAST THROUGHOUT THE EXTENDED PORTION OF THE FORECAST.
THE PERIOD BEGINS WITH A FAIRLY LOW AMPLITUDE FLOW WITH RIDGING FROM
THE SOUTHERN PLAINS THROUGH MUCH OF THE MISSISSIPPI VALLEY...AND
TROUGHING OVER THE PACIFIC NORTHWEST. MOST RECENT RUNS OF THE
GFS/ECMWF/GEM HAVE TRIED TO DIG A TROUGH INTO THE NORTHEAST OVER THE
WEEKEND...WHICH WOULD DRAG A DECENT SURFACE HIGH SOUTHWARD THROUGH
THE GREAT LAKES AND INTO THE OHIO VALLEY. THIS SURFACE HIGH COULD
POSSIBLY BACK-DOOR OUR REGION...EFFECTIVELY UNDERCUTTING THE UPPER
RIDGE...AND COOLING THINGS DOWN A NOTCH OR TWO. ANOTHER SOLUTION
NOTICED IN THE 00Z ECMWF AND 12Z GFS HAS THE ENERGY FROM THE
NORTHWEST MOVING EAST THROUGH THE TOP OF THE RIDGE...AND EVENTUALLY
BRINGING A COLD FRONT EASTWARD INTO THE REGION OVER THE WEEKEND. IN
EITHER SCENARIO...THE MODELS DIFFER IN TIMING OF POTENTIAL FRONTAL
PASSAGES.
WHAT WE CAN CONFIDENTLY SAY AT THIS POINT IS THAT PRIOR TO ANY
FRONTAL PASSAGE...IT WILL BE HOT...HUMID AND MOST LIKELY DRY. THE
AREA WILL BE ON THE NORTHERN PERIPHERY OF THE RIDGE...SO MCS/S MAY
TRACK EAST AND THEN NORTHEAST AROUND OR POSSIBLY THROUGH A PORTION
OF OUR FORECAST AREA...DEPENDING ON THE ACTUAL STRENGTH OF
THE UPPER HIGH/CAPPING INVERSION. THIS COULD BRING OUTFLOW
BOUNDARIES INTO THE AREA TO MESS UP TEMPERATURES...AND POTENTIALLY
PROVIDE A FOCUS FOR THUNDERSTORM DEVELOPMENT.
IN GENERAL WOULD LIKE TO LEAN TOWARD A DRY AND CONTINUED HOT
FORECAST UNTIL THE MODELS LOCK ONTO A REASONABLE SCENARIO.
HOWEVER...GIVEN ALL THE POTENTIAL FLIES IN THE OINTMENT...WILL
LIKELY KEEP SMALL POPS THROUGOUT THE PERIOD...WITH WARM CONDITIONS
CONTINUING THROUGH THE WEEKEND...FOLLOWED BY A MODEST COOLING TREND
EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 215 PM CDT TUE MAY 1 2012
SFC WINDS SUSTAINED AT AROUND 15 KTS WILL CONTINUE THIS AFTERNOON...
WITH SOME GUSTS TO 25 KTS COMMON. AS A MID/UPPER LEVEL IMPULSE
MOVES SLOWLY EAST ACROSS CENTRAL/NORTHERN ILLINOIS THROUGH THE
AFTERNOON...A BAND/ARC OR TWO OF SHOWERS AND THUNDERSTORMS MAY
DEVELOP TO ITS SOUTH. IT IS NOT CLEAR WHETHER THIS WILL IMPACT ANY
TAF SITES...BUT IT WILL BE MOST LIKELY AT KEVV AND KOWB DURING THE
EARLY TO MID AFTERNOON. FOR TONIGHT...A PERSISTENT SOUTH WINDS
UNDER 10 KTS SHOULD PREVENT FOG FORMATION. OF COURSE...FOG WILL BE
MORE LIKELY IF A SITE RECIEVES SIGNIFICANT RAINFALL LATER THIS
AFTERNOON. GUSTY SOUTHWEST WINDS ARE LIKELY TO DEVELOP AGAIN BY
MID-MORNING WEDNESDAY...BUT IT SHOULD BE DRY THROUGHOUT THE
REGION.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR ILZ075>078-
080>094.
MO...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR MOZ076-086-
087-100-107>112-114.
IN...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR INZ081-082-
085>088.
KY...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR KYZ001>022.
&&
$$
SHORT TERM...DB
LONG TERM....DRS
AVIATION...DB/DRS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1246 PM CDT TUE MAY 1 2012
.UPDATE...
ISSUED AT 1245 PM CDT TUE MAY 1 2012
DECIDED TO EXPAND THE LAKE WIND ADVISORY OVER THE ENTIRE FORECAST
AREA FOR THE REMAINDER OF THE AFTERNOON. WINDS THROUGHOUT THE
REGION ARE ALREADY SUSTAINED AT 15 MPH OR GREATER...WHICH IS THE
CRITERIA FOR ISSUANCE. WITH GOOD MIXING EXPECTED TO CONTINUE
THROUGHOUT THE AFTERNOON...SEE NO REASON WHY THE WINDS WOULD
WEAKEN SIGNIFICANTLY UNTIL LOSS OF HEATING.
UPDATE ISSUED AT 1110 AM CDT TUE MAY 1 2012
THE ATMOSPHERE OVER THE PAH FCST AREA IS MOIST OVERALL...AND
UNSTABLE. WE HAVE A 50+KT MID LEVEL JET MOVING THROUGH NRN PARTS
OF THE REGION...HOWEVER THE RADARS ARE VIRTUALLY CLEAR OF PCPN AT
THIS LATE MORNING HOUR. THIS MAY BE DUE TO LACK OF POSITIVE VORTICITY
ADVECTION IN THE MID LEVELS...WHICH THE RUC SHOWS MAY OCCUR A FEW
HOURS FROM NOW AS A PARENT MCV ROTATES INTO NRN IL. THOUGH NOT
EXPECTED TO BE NECESSARILY WDSPRD...SHOWER AND TSTM ACTIVITY IS
POSSIBLE WELL INTO THE AFTERNOON...MAINLY OVER SRN IL...ADJACENT
PARTS OF SERN MO...AND SWRN IND. SEVERE WX CANNOT BE RULED OUT
EAST OF THE MS RIVER THIS AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 332 AM CDT TUE MAY 1 2012
SEVERAL ISSUES TO DEAL WITH THIS FORECAST. IN THE VERY SHORT TERM
CONVECTION IS INCREASING ACROSS WEST TENNESSEE AND WEST KENTUCKY.
NOT EXACTLY WHERE THE MESOSCALE MODELS SUGGESTED...BUT SEVERAL DID
SUGGEST IT WAS GOING TO HAPPEN. PATCHY DENSE FOG DEVELOPED OVER
AREAS WHERE IT DID CLEAR OUT EARLIER. AS CLOUDS AND CONVECTION
INCREASE...EXPECT THE FOG TO THIN OUT.
THE LARGE MCS OVER WESTERN MISSOURI SHOULD HEAD THIS WAY BUT AT A
BIT SLOWER PACE THAN EARLIER THOUGHT. THIS IS ALL ASSOCIATED WITH
A DECENT SHORT WAVE THAT SHOULD PASS THROUGH THE AREA THIS
AFTERNOON.
NOT A GREAT SETUP FOR SEVERE WEATHER BUT AN ISOLATED SEVERE STORM
IS POSSIBLE. HAD AN EARLIER REPORT OF MEASURED 40 MPH WINDS IN
CALLOWAY COUNTY. THE COLUMN MOISTENS UP CONSIDERABLY ACCORDING TO
FORECAST SOUNDINGS FROM NAM AND GFS. SO MUCH SO THAT HEAVY RAIN IS
PROBABLY THE BIGGEST THREAT TODAY AS PRECIPITABLE WATER VALUES GO
ABOVE 2 STANDARD DEVIATIONS FROM CLIMO. HAVE PUT THIS WORDING IN
THE GRIDS FOR THE MORNING HOURS WHEN WE EXPECT THE MOST COVERAGE.
FFG VALUES TOO HIGH FOR ANY WATCH CONSIDERATIONS AS THE GROUND IS
VERY DRY IN MOST OF THE AREA.
AFTER THIS SHORT WAVE PASSES THE RIDGE BUILDS OVER THE AREA FOR
WEDNESDAY AND THURSDAY WITH SUMMER WEATHER. SOME RECORDS MAY FALL.
HUMIDITY LEVELS MAY NOT BE BAD ON WEDNESDAY WITH SOME AFTERNOON
MIXING BUT THE MOISTURE INCREASES IN DEPTH ON THURSDAY SO NOT A
LOT OF DRY AIR TO MIX DOWN EVEN WITH GUSTY WINDS.
GOING TEMPERATURES ON WEDNESDAY LOOKED PRETTY GOOD WITH ONLY MINOR
ADJUSTMENTS. HOWEVER...RAISED MAX TEMPS ON THURSDAY AS 850
TEMPERATURES DO NOT CHANGE MUCH AND MAY ACTUALLY RISE A DEGREE OR
TWO IN SOME AREAS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 332 AM CDT TUE MAY 1 2012
AS ALLUDED TO WITH MONDAY MORNINGS FORECAST PACKAGE...THE SOUTHEAST
U.S. RIDGE /ALREADY EVIDENT IN THE THE 00Z TUESDAY MANDATORY UPPER
AIR CHARTS/ WILL SLOWLY RETROGRADE AND BUILD WEST INTO THE LOWER
MISSISSIPPI VALLEY THURSDAY. AT THE BEGINNING OF THIS TIME PERIOD
/THURSDAY NIGHT INTO FRIDAY/ THE DETERMINISTIC GFS/CANADIAN MODEL
SUITES ATTEMPT TO WORK IN A CLOSED LOW OVER NORTHEAST TEXAS /ITS
ORIGINS MOSTLY LIKELY NEAR EL PASO TEXAS EARLY THIS
EVENING/...DISRUPTING BROAD INFLUENCE OF THE UPPER AIR RIDGE AXIS
INTO THE PLAINS FRIDAY INTO SATURDAY AND SLIGHTLY MODIFYING THE
THERMAL PROFILE OVER THE WFO PAH FORECAST AREA...ENOUGH FOR
CONVECTION TO MOVE INTO THE AREA.
ALTHOUGH THERE IS SOME VARIABILITY IN THE PLACEMENT OF THE RIDGE
FROM THE CANADIAN VERSUS TH GFS GUIDANCE OVER THE WEEKEND...BOTH
KEEP THE WFO PAH FORECAST AREA WITHIN THE WARM SECTOR INTO EARLY
NEXT WEEK. THERE IS ALSO SOME INDICATION THAT THE WFO PAH FORECAST
AREA IS ALSO IN A FAVORABLE ZONE FOR ISENTROPIC LIFT...FOCUSED MORE
TOWARD SOUTHERN ILLINOIS...THE PENNYRILE REGION OF WEST KENTUCKY AND
SOUTHWEST INDIANA. THIS AREA WILL LIKELY SEE THE BRUNT OF THE DAILY
CONVECTIVE ACTIVITY OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
ALTHOUGH THE GFS HAS BEEN RECENTLY RUNNING 6-12 HOURS FASTER WITH
THE MOVEMENT OF THE WEATHER SYSTEMS ACROSS THE AREA...IT IS HINTING
A SHIFT TOWARD A MORE NORTHWESTERLY FLOW AROUND THE RIDGE OVER THE
REGION...BRINGING THE BASE OF THE WESTERLIES OVER NORTHEAST SECTIONS
OF THE WFO PAH FORECAST AREA. THIS MAY BE A LITTLE OVERDONE...BUT IT
IS DIFFICULT TO RULE OUT WIDELY SCATTERED TO SCATTERED CONVECTIVE
ACTIVITY OVER MOST OF THE AREA THURSDAY INTO EARLY SATURDAY...THEN
AGAIN MONDAY INTO TUESDAY OF NEXT WEEK. AT THIS TIME...SUNDAY
APPEARS THE LEAST IMPACTED BY CONVECTION AND THE RIDGE IS THE
STRONGEST OVER THE REGION AT THIS TIME PER MODEL GUIDANCE.
TEMPERATURES FOR THE EXTENDED PERIOD OF THE FORECAST WILL REMAIN 10
TO 15 DEGREES ABOVE NORMAL...SIMILAR TO THE CURRENT SHORT TERM TIME
PERIOD.
DUE TO RUN TO RUN DISCREPANCIES...THE ECMWF GUIDANCE WAS NOT UTILIZED
WITH THIS PACKAGE...ESPECIALLY WITH RESPECT TO POP/WEATHER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1110 AM CDT TUE MAY 1 2012
GUSTY SOUTHWEST WINDS WILL DEVELOP THROUGHOUT THE AREA BY 18Z. SOME
GUSTS TO 25 KTS WILL BE POSSIBLE. AS A MID/UPPER LEVEL IMPULSE
MOVES SLOWLY EAST ACROSS CENTRAL/NORTHERN ILLINOIS THROUGH THE
AFTERNOON...A BAND/ARC OR TWO OF SHOWERS AND THUNDERSTORMS ARE
LIKELY TO DEVELOP TO ITS SOUTH. IT IS NOT CLEAR WHETHER THIS WILL
IMPACT ANY TAF SITES...BUT IT WILL BE MOST LIKELY AT KEVV AND KOWB
DURING THE EARLY TO MID AFTERNOON. FOR TONIGHT...A PERSISTENT SOUTH
WINDS UNDER 10 KTS SHOULD PREVENT FOG FORMATION. OF COURSE...FOG
WILL BE MORE LIKELY IF A SITE RECIEVES SIGNIFICANT RAINFALL LATER
THIS AFTERNOON. GUSTY SOUTHWEST WINDS ARE LIKELY TO DEVELOP AGAIN BY
MID-MORNING WEDNESDAY...BUT IT SHOULD BE DRY THROUGHOUT THE REGION.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR ILZ075>078-
080>094.
MO...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR MOZ076-086-
087-100-107>112-114.
IN...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR INZ081-082-
085>088.
KY...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR KYZ001>022.
&&
$$
UPDATE...DRS/DB
SHORT TERM...PS
LONG TERM....KES
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1110 AM CDT TUE MAY 1 2012
.UPDATE...
ISSUED AT 1110 AM CDT TUE MAY 1 2012
THE ATMOSPHERE OVER THE PAH FCST AREA IS MOIST OVERALL...AND
UNSTABLE. WE HAVE A 50+KT MID LEVEL JET MOVING THROUGH NRN PARTS
OF THE REGION...HOWEVER THE RADARS ARE VIRTUALLY CLEAR OF PCPN AT
THIS LATE MORNING HOUR. THIS MAY BE DUE TO LACK OF POSITIVE VORTICITY
ADVECTION IN THE MID LEVELS...WHICH THE RUC SHOWS MAY OCCUR A FEW
HOURS FROM NOW AS A PARENT MCV ROTATES INTO NRN IL. THOUGH NOT
EXPECTED TO BE NECESSARILY WDSPRD...SHOWER AND TSTM ACTIVITY IS
POSSIBLE WELL INTO THE AFTERNOON...MAINLY OVER SRN IL...ADJACENT
PARTS OF SERN MO...AND SWRN IND. SEVERE WX CANNOT BE RULED OUT
EAST OF THE MS RIVER THIS AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 332 AM CDT TUE MAY 1 2012
SEVERAL ISSUES TO DEAL WITH THIS FORECAST. IN THE VERY SHORT TERM
CONVECTION IS INCREASING ACROSS WEST TENNESSEE AND WEST KENTUCKY.
NOT EXACTLY WHERE THE MESOSCALE MODELS SUGGESTED...BUT SEVERAL DID
SUGGEST IT WAS GOING TO HAPPEN. PATCHY DENSE FOG DEVELOPED OVER
AREAS WHERE IT DID CLEAR OUT EARLIER. AS CLOUDS AND CONVECTION
INCREASE...EXPECT THE FOG TO THIN OUT.
THE LARGE MCS OVER WESTERN MISSOURI SHOULD HEAD THIS WAY BUT AT A
BIT SLOWER PACE THAN EARLIER THOUGHT. THIS IS ALL ASSOCIATED WITH
A DECENT SHORT WAVE THAT SHOULD PASS THROUGH THE AREA THIS
AFTERNOON.
NOT A GREAT SETUP FOR SEVERE WEATHER BUT AN ISOLATED SEVERE STORM
IS POSSIBLE. HAD AN EARLIER REPORT OF MEASURED 40 MPH WINDS IN
CALLOWAY COUNTY. THE COLUMN MOISTENS UP CONSIDERABLY ACCORDING TO
FORECAST SOUNDINGS FROM NAM AND GFS. SO MUCH SO THAT HEAVY RAIN IS
PROBABLY THE BIGGEST THREAT TODAY AS PRECIPITABLE WATER VALUES GO
ABOVE 2 STANDARD DEVIATIONS FROM CLIMO. HAVE PUT THIS WORDING IN
THE GRIDS FOR THE MORNING HOURS WHEN WE EXPECT THE MOST COVERAGE.
FFG VALUES TOO HIGH FOR ANY WATCH CONSIDERATIONS AS THE GROUND IS
VERY DRY IN MOST OF THE AREA.
AFTER THIS SHORT WAVE PASSES THE RIDGE BUILDS OVER THE AREA FOR
WEDNESDAY AND THURSDAY WITH SUMMER WEATHER. SOME RECORDS MAY FALL.
HUMIDITY LEVELS MAY NOT BE BAD ON WEDNESDAY WITH SOME AFTERNOON
MIXING BUT THE MOISTURE INCREASES IN DEPTH ON THURSDAY SO NOT A
LOT OF DRY AIR TO MIX DOWN EVEN WITH GUSTY WINDS.
GOING TEMPERATURES ON WEDNESDAY LOOKED PRETTY GOOD WITH ONLY MINOR
ADJUSTMENTS. HOWEVER...RAISED MAX TEMPS ON THURSDAY AS 850
TEMPERATURES DO NOT CHANGE MUCH AND MAY ACTUALLY RISE A DEGREE OR
TWO IN SOME AREAS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 332 AM CDT TUE MAY 1 2012
AS ALLUDED TO WITH MONDAY MORNINGS FORECAST PACKAGE...THE SOUTHEAST
U.S. RIDGE /ALREADY EVIDENT IN THE THE 00Z TUESDAY MANDATORY UPPER
AIR CHARTS/ WILL SLOWLY RETROGRADE AND BUILD WEST INTO THE LOWER
MISSISSIPPI VALLEY THURSDAY. AT THE BEGINNING OF THIS TIME PERIOD
/THURSDAY NIGHT INTO FRIDAY/ THE DETERMINISTIC GFS/CANADIAN MODEL
SUITES ATTEMPT TO WORK IN A CLOSED LOW OVER NORTHEAST TEXAS /ITS
ORIGINS MOSTLY LIKELY NEAR EL PASO TEXAS EARLY THIS
EVENING/...DISRUPTING BROAD INFLUENCE OF THE UPPER AIR RIDGE AXIS
INTO THE PLAINS FRIDAY INTO SATURDAY AND SLIGHTLY MODIFYING THE
THERMAL PROFILE OVER THE WFO PAH FORECAST AREA...ENOUGH FOR
CONVECTION TO MOVE INTO THE AREA.
ALTHOUGH THERE IS SOME VARIABILITY IN THE PLACEMENT OF THE RIDGE
FROM THE CANADIAN VERSUS TH GFS GUIDANCE OVER THE WEEKEND...BOTH
KEEP THE WFO PAH FORECAST AREA WITHIN THE WARM SECTOR INTO EARLY
NEXT WEEK. THERE IS ALSO SOME INDICATION THAT THE WFO PAH FORECAST
AREA IS ALSO IN A FAVORABLE ZONE FOR ISENTROPIC LIFT...FOCUSED MORE
TOWARD SOUTHERN ILLINOIS...THE PENNYRILE REGION OF WEST KENTUCKY AND
SOUTHWEST INDIANA. THIS AREA WILL LIKELY SEE THE BRUNT OF THE DAILY
CONVECTIVE ACTIVITY OVER THE WEEKEND AND INTO EARLY NEXT WEEK.
ALTHOUGH THE GFS HAS BEEN RECENTLY RUNNING 6-12 HOURS FASTER WITH
THE MOVEMENT OF THE WEATHER SYSTEMS ACROSS THE AREA...IT IS HINTING
A SHIFT TOWARD A MORE NORTHWESTERLY FLOW AROUND THE RIDGE OVER THE
REGION...BRINGING THE BASE OF THE WESTERLIES OVER NORTHEAST SECTIONS
OF THE WFO PAH FORECAST AREA. THIS MAY BE A LITTLE OVERDONE...BUT IT
IS DIFFICULT TO RULE OUT WIDELY SCATTERED TO SCATTERED CONVECTIVE
ACTIVITY OVER MOST OF THE AREA THURSDAY INTO EARLY SATURDAY...THEN
AGAIN MONDAY INTO TUESDAY OF NEXT WEEK. AT THIS TIME...SUNDAY
APPEARS THE LEAST IMPACTED BY CONVECTION AND THE RIDGE IS THE
STRONGEST OVER THE REGION AT THIS TIME PER MODEL GUIDANCE.
TEMPERATURES FOR THE EXTENDED PERIOD OF THE FORECAST WILL REMAIN 10
TO 15 DEGREES ABOVE NORMAL...SIMILAR TO THE CURRENT SHORT TERM TIME
PERIOD.
DUE TO RUN TO RUN DISCREPANCIES...THE ECMWF GUIDANCE WAS NOT UTILIZED
WITH THIS PACKAGE...ESPECIALLY WITH RESPECT TO POP/WEATHER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1110 AM CDT TUE MAY 1 2012
GUSTY SOUTHWEST WINDS WILL DEVELOP THROUGHOUT THE AREA BY 18Z. SOME
GUSTS TO 25 KTS WILL BE POSSIBLE. AS A MID/UPPER LEVEL IMPULSE
MOVES SLOWLY EAST ACROSS CENTRAL/NORTHERN ILLINOIS THROUGH THE
AFTERNOON...A BAND/ARC OR TWO OF SHOWERS AND THUNDERSTORMS ARE
LIKELY TO DEVELOP TO ITS SOUTH. IT IS NOT CLEAR WHETHER THIS WILL
IMPACT ANY TAF SITES...BUT IT WILL BE MOST LIKELY AT KEVV AND KOWB
DURING THE EARLY TO MID AFTERNOON. FOR TONIGHT...A PERSISTENT SOUTH
WINDS UNDER 10 KTS SHOULD PREVENT FOG FORMATION. OF COURSE...FOG
WILL BE MORE LIKELY IF A SITE RECIEVES SIGNIFICANT RAINFALL LATER
THIS AFTERNOON. GUSTY SOUTHWEST WINDS ARE LIKELY TO DEVELOP AGAIN BY
MID-MORNING WEDNESDAY...BUT IT SHOULD BE DRY THROUGHOUT THE REGION.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR ILZ075-076-
080>082-084>086-088-089-092-093.
MO...LAKE WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR MOZ076-086-
087-108>112-114.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DB
SHORT TERM...PS
LONG TERM....KES
AVIATION...DRS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
819 PM EDT WED MAY 2 2012
.SYNOPSIS...
A STATIONARY FRONT PERSISTS ACROSS THE MID ATLANTIC TONIGHT. HIGH
PRESSURE WILL BUILD OVER THE AREA THURSDAY AND THURSDAY NIGHT. A COLD
FRONT WILL SAG SOUTH THROUGH THE AREA DURING THE WEEKEND...WITH
ACTIVE WEATHER CONTINUING INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 8 AM THURSDAY MORNING/...
THE FRONTAL BOUNDARY INCHED WEST LATE THIS AFTERNOON TO BE ALONG
THE NORTHERN BLUE RIDGE DOWN TO SERN VA. THUNDERSTORMS DEVELOPED
IN THE UNSTABLE AIR WEST OF THIS BOUNDARY OVER NWRN VA AND ERN WV
AND QUICKLY DIED EAST OF THE BLUE RIDGE/THE FRONTAL BOUNDARY. NO
FURTHER DEVELOPMENT IS EXPECTED NW OF DC THIS EVENING DUE TO THE
STABLE/COOL AIR AND SUNSET. FARTHER SOUTH...ACTIVITY SOUTH OF KCHO
WILL CONTINUE TO MOVE EAST. THAT AREA IS WARM AND THERE SHOULD BE
INSTABILITY...SO SOME SHOWER/THUNDERSTORM ACTIVITY MAY CONTINUE TO
DEVELOP.
HOWEVER...THE NIGHT WILL NOT BE ALL QUIET. THE HRRR MODEL CAME
BACK STARTING WITH A 19Z RUN AND HAS BEEN FEATURING AN MCS
DEVELOPING NEAR LAKE ERIE AND TRACKING SE TOWARD THE MASON-DIXON
OVERNIGHT. WELL A LINE OF THUNDERSTORMS BETWEEN BRADFORD AND ERIE
PA HAVE DEVELOPED. THIS ACTIVITY IS MOVING EAST...AND THE SRN EXTENT
OF THIS LINE DOES NOT SEEM TO BE DEVELOPING SOUTH AT THIS
TIME...SO THIS WILL BE A WAIT AND SEE. 18Z GFS 500MB FLOW DOES
VEER NWLY FROM 00Z TO 06Z TONIGHT...SO THIS LINE SHOULD TAKE A BIT
OF A RIGHT TURN. WILL HAVE TO WAIT AND SEE. THE 21Z HRRR IS TOO
SLOW ON DEVELOPING THE CURRENT ACTIVITY. ANYTHING THAT DOES ARRIVE
WOULD BE AFTER 2AM FOR THE MASON-DIXON...4AM FOR THE BALT-WASH
METRO. CHANCE POPS FOR THUNDERSTORMS WERE ADDED TO MOST OF THE CWA
FOR LATE NIGHT. HOWEVER...WITH THE WEDGE IN PLACE...ANY ACTIVITY
WOULD BE ELEVATED OVER THE METRO AREAS...REALLY LIMITING THE
SEVERE THREAT. HOPEFULLY IT WILL BRING NEEDED RAIN.
&&
.SHORT TERM /8 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
AS HAS BEEN PREDICTED BY THE MDLS FOR THE PAST SVRL DAYS IT
APPEARS A SHORT WV RDG WL BUILD OVER THE SERN U.S. TMRW...XTNDG
INTO THE MID ATLC RGN. THIS SHOULD PRODUCE A WARM DAY W/ HIGH TEMPS
RANGING FM NEAR 90 IN THE CENTRAL SHEN VLLY TO U70S IN THE
HIGHLANDS. MAJORITY OF CWA WL TOP OUT IN THE MU80S. IF ANY CNVCTN
DOES BRK OUT THU IT WL MOST LKLY SEE ITS ORIGINS OVR THE HIGHER
WRN TERRAIN AND WORK ITS WAY E IN THE LATE AFTN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
SUMMER-LIKE PATTERN...WITH WARM AND HUMID CONDITIONS...WILL CONTINUE
THRU THE FIRST HALF OF THE WEEKEND.
HIPRES WILL REMAIN PARKED OVER THE SOUTHEAST STATES LATE IN THE
WEEK. THE UPPER RIDGE WILL INFLUENCE THE ERN SEABOARD THU EVE. AN
UPPER SHORTWAVE TROUGH...WHICH IS ASSOCIATED WITH AN MCS THAT IS
CURRENTLY OVER THE NRN GULF COAST...WILL TRACK NEWD AND BREAK DOWN
THE NRN PERIPHERY OF THE UPPER RIDGE ERY FRI. HAVE INCREASED POPS
ACROSS THE POTOMAC HIGHLANDS AND SHENANDOAH VLY LATE THU NGT/FRI
MRNG AS THE SHORTWAVE TROUGH APPROACHES. INSTABILITY SHOULD BE
ELEVATED AND LIMITED DUE TO NOCTURNAL TIMING...BUT ENOUGH TO MENTION
ISO TSTM.
FRI/FRI NGT FCST WILL ULTIMATELY DEPEND ON TIMING OF SHORTWAVE
TROUGHS AS THEY MOVE THRU THE CWA. EACH DISTURBANCE WILL BRING
CHANCES FOR SHOWERS AND STORMS...ESPECIALLY IF TROUGH PASSAGE
COINCIDES WITH PEAK HEATING. STORM COVERAGE SHOULD BE HIGHEST OVER
THE HIGHER TERRAIN.
FCST UNCERTAINTY INCREASES THIS WEEKEND AS MODELS DISAGREE WITH
EXTENT OF TROUGH DEVELOPMENT OVER THE NORTHEAST STATES. THE
OPERATIONAL GFS CONTINUES TO BE THE MOST PRONOUNCED WITH SWD
PROGRESSION OF A COLD FRONT SAT AND SWD RIDGING OF CANADIAN HIPRES
ON SUN. IF THIS GFS SOLUTION WAS THE CASE...NWLY FLOW BEHIND THE
FRONT WILL ALLOW COOLER/DRIER AIR TO REACH THE CWA. CONVECTIVE
ACTIVITY ALONG THE FRONT WOULD ACCORDINGLY SHIFT SOUTH OF THE REGION
BY SAT NGT OR SUN. HOWEVER...IF THE BREAK DOWN OF THE RIDGE IS
DELAYED...THEN THE FRONTAL BOUNDARY MAY GET HUNG UP NEAR OR JUST
SOUTH OF THE CWA LATE THIS WEEKEND. ATTM...HAVE TRENDED SLIGHTLY
TOWARD A DRIER/COOLER SOLUTION.
THE NEXT LOPRES SYSTEM MAY IMPACT THE REGION MIDWEEK. THE TRACK OF
THE LOW...WHICH IS UNCERTAIN ATTM...WILL DETERMINE HOW FAR NORTH THE
WARM SECTOR ADVANCES. NONETHELESS...CHANCES FOR UNSETTLED WX
INCREASE AS THE LOW APPROACHES.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
THUNDERSTORM THREAT HAS ENDED FOR THE TERMINALS THIS
EVENING...THOUGH MORE THUNDERSTORMS ARE POSSIBLE LATE TONIGHT.
CEILINGS WILL REDEVELOP AND LOWER ACROSS THE BALT-WASH
METRO...WITH IFR CIGS EXPECTED AROUND MIDNIGHT FOR TAFS EXCEPT
KCHO. LOW VSBYS IN BR/DZ...OR EVEN ELEVATED SHOWERS POSSIBLE
TOWARD MORNING. IFR CIGS HOLD ON INTO THE LATE
MORNING...PARTICULARLY FOR KBWI AND KMTN.
A SERIES OF SHORTWAVE DISTURBANCES WILL MOVE ATOP AN UPPER RIDGE THU
NGT-SAT. GUIDANCE HINTS AT MOISTURE BECOMING TRAPPED BELOW STRONG
SUBSIDENCE INVERSION THU NGT. DEPENDING ON IMPACT FROM DEBRIS CI
ASSOCIATED WITH MCS ACTIVITY...LOW STRATUS/FOG MAY DEVELOP ERY FRI
MRNG...ESPECIALLY ACROSS THE ERN TERMINALS. OTHERWISE...TEMPORARY
REDUCTION OF CIGS/VSBYS MAY OCCUR WITH ISO-SCT SHRA/TSRA FRI AND
SAT. THE BEST CHANCE FOR DRY WX WILL BE SUN AS HIPRES TRIES TO BUILD
SWD.
&&
.MARINE...
ELY SURGE HAS SHIFTED EAST TO THE TIDAL POTOMAC...OTHERWISE EXPECT
ELY FLOW 10 TO 15 KT OVER NIGHT. WINDS SHIFT SWLY THROUGH THE DAY
TOMORROW AS HIGH PRESSURE BUILDS.
UNDER THE INFLUENCE OF HIPRES...WINDS SHOULD REMAIN BELOW SCA LVLS
LATE THIS WEEK AND WEEKEND. MAIN CONCERN WILL BE POTENTIAL FOR
DEVELOPMENT OF ISO TSTMS FRI. SLIGHTLY BETTER CHANCE OF STORMS SAT
AS COLD FRONT PASSES THRU THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
UPDATE...JACKSON
PREVIOUS DISCUSSION...ABW/JRK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
131 PM EDT TUE MAY 1 2012
.SYNOPSIS...
ISSUED AT 345 AM EDT TUE MAY 1 2012
A MAINLY QUIET DAY IS EXPECTED FOR TODAY AS A FRONTAL SYSTEM
REMAINS SOUTH OF THE AREA THROUGH THE DAY. THE CHANCE OF SHOWERS
AND STORMS WILL GRADUALLY INCREASE LATE THIS AFTERNOON THROUGH
WEDNESDAY MORNING AS THE FRONT LIFTS NORTH ACROSS THE STATE. WE
WILL THEN SEE CHANCES FOR SHOWERS AND STORMS THROUGH THE WEEKEND
WITH WARM WEATHER HOLDING IN THROUGH THEN.
&&
.UPDATE...
ISSUED AT 1240 PM EDT TUE MAY 1 2012
INCREASED POPS AND LOWERED TEMPS THIS AFTERNOON FOR SOUTHERN
LOCATIONS. RADAR SHOWS THE BAND OF SHOWERS APPROACHING FROM THE
SOUTH AND THEY SHOULD MOVE INTO THE I94 CORRIDOR BY 21Z. THE MOST
RECENT TREND HAS THEM WEAKENING.
UPDATE ISSUED AT 800 AM EDT TUE MAY 1 2012
I HAVE NOTED THE MCV OVER MO HEADING NORTHEAST TOWARD SOUTHERN
LOWER MICHIGAN BY LATE AFTERNOON. THE HRRR AND RUC SEEM TO LIKE
THE FEATURE AND THE RUC SHOWS A 40 KNOT LLJ INTO CNTL IL BY 18Z.
THE HRRR KEEPS THE ACTUAL THUNDERSTORMS NEAR AND SOUTH OF I-80 BUT
BRINGS RAIN SOUTH OF I-96 BY 20Z. SO AFTER TALKING WITH IWX SHORT
TERM... WE DECIDED TO GO AHEAD AND BRING THE CONVECTION IN MID TO
LATE AFTERNOON. THE UPDATED GRIDS AND ZONES HAVE BEEN ISSUED
ALREADY.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 345 AM EDT TUE MAY 1 2012
THE MAIN FORECAST CHALLENGE THROUGH THE SHORT TERM WILL BE
DETERMINING CONVECTIVE TRENDS THROUGH THE PERIOD AS A FRONTAL
SYSTEM WILL RESIDE ACROSS THE REGION THROUGH THE PERIOD.
THE QUIETEST PERIOD OF THE SHORT TERM IS EXPECTED TO BE THE DAY
TODAY. THE AREA CONTINUES TO BE SHROUDED IN CLOUD COVER EARLY THIS
MORNING. THE CLEARING LINE...NOW ACROSS ERN WISCONSIN...IS
EXPECTED TO MOVE ACROSS THE AREA THIS MORNING. FAR WESTERN AREAS
COULD SEE SOME FOG DEVELOP IF IT CLEARS OUT EARLY ENOUGH BEFORE
DAYBREAK. WE DO NOT EXPECT THERE WILL BE ENOUGH TIME FOR THE FOG TO
BECOME A PROBLEM.
WE SHOULD SEE A DECENT AMOUNT OF SUNSHINE DURING THE DAY TODAY
WITH SOME MID/HIGH CLOUDS FLOATING ACROSS THE AREA. LATE IN THE
DAY ACROSS THE FAR SOUTH...WE WILL BEGIN TO SEE AN INFLUX OF
MOISTURE AS WAA/ISENTROPIC ASCENT INCREASES WITH THE APPROACH OF
THE STALLED OUT FRONT TO OUR SOUTH. WE MAY SEE JUST ENOUGH MOISTURE
ADVECTION FOR A LOW CHC OF A FEW SHOWERS/STORM LATE ACROSS THE SRN
COUNTIES. H850 TEMPS OF AROUND 10 TO 12C SUPPORT HIGHS IN THE 70S.
THE WARM AND MOIST ADVECTION WILL CONTINUE INTO TONIGHT AS THE LOW
LEVEL JET NOSES IN FROM THE SW LATER TONIGHT. WE EXPECT TO SEE THE
BEST THREAT OF SHOWERS/STORMS ACROSS THE SRN HALF OF THE CWFA
DURING THE LAST HALF OF THE NIGHT TONIGHT. MOISTURE TRANSPORT IS
FCST TO SPREAD ACROSS THE ENTIRE AREA...SO A CHC/SCT
SHOWERS/STORMS WILL BE EXPECTED EVEN NORTH. THIN CAPE PROFILES AND
THE ELEVATED NATURE OF THE STORMS SHOULD LIMIT SEVERE
POTENTIAL...EVEN WITH BULK SHEAR VALUES AROUND 25-35 KNOTS.
CONVECTION WILL STILL LIKELY BE AROUND THE AREA FIRST THING WED
MORNING. MODELS INDICATE THAT THE SFC WAVE MOVING NW OF THE AREA
SHOULD DRAW THE FRONT TO THE NORTH OF THE CWFA IN THE AFTERNOON.
THE SURGE OF MOISTURE TRANSPORT WILL PULL OUT IN THE AFTERNOON...
AND WE COULD SEE CLEARING TAKE PLACE AS WE GET INTO THE WARM
SECTOR. IF THIS WAS TO OCCUR...WE WOULD EASILY SEE TEMPS HIT 80 AT
INLAND LOCATIONS. CONVECTION CHCS LOOK TO DECREASE AS THE
ATMOSPHERE LOOKS TO BECOME CAPPED. STILL NOT IMPOSSIBLE TO SEE
ANOTHER WAVE MOVE THROUGH HOWEVER...SO WE KEPT A CHC IN DURING THE
AFTERNOON.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 345 AM EDT TUE MAY 1 2012
CONVECTION IS EXPECTED TO SOME EXTENT EACH DAY. THE GREATEST CHANCE
FOR STRONG STORMS IS WEDNESDAY NIGHT AND THURSDAY NIGHT (WHEN
THE LOW LEVEL IS CLOSEST). TEMPERATURES WILL UNSEASONABLY WARM INTO
FRIDAY THEN COOL OFF SOME INTO THE WEEKEND.
OVER THE PAST FEW DAYS WE HAVE BEEN WATCHING HOW THE POLAR JET
MIGRATES NORTHWARD INTO SOUTHERN CANADA THE SECOND HALF OF THIS
WEEK INTO THE WEEKEND. THAT IS THE RESULT OF THE WESTERN TROUGH
DEEPENING AND BUILDING AN UPSTREAM RIDGE OVER THE CENTRAL CONUS.
THE FARTHER NORTH THE JET GETS THE LESS LIKELY IS STRONG CONVECTION
HERE. THAT IS MOSTLY DUE TO THE LACK OF DEEP LAYERED SHEAR. THE
MODELS ARE ALL IN GOOD AGREEMENT THAT FEATURE OF THE FORECAST.
THE REAL FORECAST PROBLEMS COME IN OVER THE WEEKEND AS THE ECMWF
CONTINUES TO KEEP THE UPPER LOW OVER NE CANADA OVER NE CANADA WHILE
THE GFS CONTINUES TO DIG THE FEATURE SOUTH SOUTHEAST TOWARD NEW
ENGLAND BY LATE IN THE WEEKEND. THE END RESULT IS THE ECMWF KEEPS
THE FRONT NEAR SOUTHWEST MICHIGAN THROUGH THE WEEKEND WHICH IN TURN
KEEPS THE THREAT FOR CONVECTION EACH DAY. MEANWHILE WITH THE GFS
BRINGING THE UPPER LOW SOUTH SOUTHEAST IT ALSO BRINGS CANADIAN POLAR
AIR SOUTH INTO THE GREAT LAKES SATURDAY NIGHT INTO SUNDAY. THAT OF
COURSE DRIES OUT THE AIR AND ENDS THE RISK FOR CONVECTION BY
SATURDAY NIGHT. I AM SIDING WITH THE ECMWF HERE.
THE LOW LEVEL JET MOVES THROUGH SOUTHWEST MICHIGAN THURSDAY NIGHT
INTO FRIDAY MORNING. THAT IS WHEN THERE SHOULD BE THE GREATEST
THREAT FOR THUNDERSTORMS FOR SOUTHWEST LOWER MICHIGAN. HOWEVER WITH
THE UPPER JET WELL NORTH IN CANADA...THESE STORMS SHOULD NOT BE ALL
THAT STRONG. OVER THE WEEKEND I AM LEANING TOWARD THE ECMWF INTO THE
WEEKEND BUT DUE TO INCREASING UNCERTAINLY WE HAVE LOWER POPS
SATURDAY AND SUNDAY.
WITH THE POLAR JET SO FAR NORTH AND THE SURFACE FRONT NORTH OF
SOUTHWEST LOWER MICHIGAN THURSDAY... IT SHOULD BE VERY WARM. LOW
LEVEL THICKNESS TOOLS SUPPORT HIGHS IN THE MID 80S... EVEN WITH A
FEW CLOUDS AND SHOWERS AROUND. THE FRONT SAGS SOUTH FRIDAY AND
STALLS SATURDAY... DUE TO CLOSENESS OF THE FRONT HIGHS WILL ONLY BE
IN THE 70S FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 131 PM EDT TUE MAY 1 2012
RAIN SHOWERS WERE APPROACHING THE AREA AS OF 1730Z FROM THE SW.
THESE SHOULD ONLY IMPACT THE I-94 TAF SITES AFTER 20-21Z. HOWEVER
ANY THUNDER IS EXPECTED TO REMAIN SOUTH OF THE MI/IN BORDER. THESE
SHOWERS MAY BRING THE I-94 TAFS DOWN INTO THE MVFR RANGE LATER
THIS EVENING...WHILE THE I-96 SITES REMAIN VFR. EXPECT THAT MUCH
OF THE MVFR WILL LIFT OUT OF THE AREA BY EARLY TO MID WED MORNING.
THERE SHOULD BE A MORE WIDESPREAD AREA OF SHOWERS AND SCATTERED
THUNDERSTORMS THAT MOVES INTO THE AREA AFTER 09Z WED. THIS COULD
LINGER THROUGH 18Z.
&&
.MARINE...
ISSUED AT 1240 PM EDT TUE MAY 1 2012
SOUTH WINDS WILL REMAIN UNDER 20 KNOTS SO NOT MUCH IMPACT TO
MARINERS EXPECTED FOR THE NEXT FEW DAYS. THERE WILL BE SOME
THUNDERSTORMS THAT WILL POSE A RISK TO MARINERS
&&
.HYDROLOGY...
ISSUED AT 345 AM EDT TUE MAY 1 2012
A FAIRLY MOISTURE RICH AIR MASS WILL MOVE IN BEGINNING LATE TODAY
AND ESPECIALLY TONIGHT. PRECIPITABLE WATER IS EXPECTED TO INCREASE
TO 1.25 TO 1.50 INCHES TONIGHT. THIS AIR MASS SHOULD REMAIN IN
PLACE THROUGH THE REMAINDER OF THE WEEK AND INTO THE WEEKEND. THIS
WILL ALLOW FOR LOCALLY HEAVY RAINFALL TO OCCUR WITH ANY
SHOWERS/STORMS. WE SHOULD NOT HAVE ANY ISSUES WITH THIS. THE ONLY
ISSUE THAT COULD ARISE WOULD BE IF WAVES OF SHOWERS/STORMS START
ROLLING OVER THE SAME AREAS DURING THE NEXT FEW DAYS. THE TRACK OF
ANY SHOWERS/STORMS IS QUITE UNCERTAIN AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...JK
HYDROLOGY...NJJ
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1243 PM EDT TUE MAY 1 2012
.SYNOPSIS...
ISSUED AT 345 AM EDT TUE MAY 1 2012
A MAINLY QUIET DAY IS EXPECTED FOR TODAY AS A FRONTAL SYSTEM
REMAINS SOUTH OF THE AREA THROUGH THE DAY. THE CHANCE OF SHOWERS
AND STORMS WILL GRADUALLY INCREASE LATE THIS AFTERNOON THROUGH
WEDNESDAY MORNING AS THE FRONT LIFTS NORTH ACROSS THE STATE. WE
WILL THEN SEE CHANCES FOR SHOWERS AND STORMS THROUGH THE WEEKEND
WITH WARM WEATHER HOLDING IN THROUGH THEN.
&&
.UPDATE...
ISSUED AT 1240 PM EDT TUE MAY 1 2012
INCREASED POPS AND LOWERED TEMPS THIS AFTERNOON FOR SOUTHERN
LOCATIONS. RADAR SHOWS THE BAND OF SHOWERS APPROACHING FROM THE
SOUTH AND THEY SHOULD MOVE INTO THE I94 CORRIDOR BY 21Z. THE MOST
RECENT TREND HAS THEM WEAKENING.
UPDATE ISSUED AT 800 AM EDT TUE MAY 1 2012
I HAVE NOTED THE MCV OVER MO HEADING NORTHEAST TOWARD SOUTHERN
LOWER MICHIGAN BY LATE AFTERNOON. THE HRRR AND RUC SEEM TO LIKE
THE FEATURE AND THE RUC SHOWS A 40 KNOT LLJ INTO CNTL IL BY 18Z.
THE HRRR KEEPS THE ACTUAL THUNDERSTORMS NEAR AND SOUTH OF I-80 BUT
BRINGS RAIN SOUTH OF I-96 BY 20Z. SO AFTER TALKING WITH IWX SHORT
TERM... WE DECIDED TO GO AHEAD AND BRING THE CONVECTION IN MID TO
LATE AFTERNOON. THE UPDATED GRIDS AND ZONES HAVE BEEN ISSUED
ALREADY.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 345 AM EDT TUE MAY 1 2012
THE MAIN FORECAST CHALLENGE THROUGH THE SHORT TERM WILL BE
DETERMINING CONVECTIVE TRENDS THROUGH THE PERIOD AS A FRONTAL
SYSTEM WILL RESIDE ACROSS THE REGION THROUGH THE PERIOD.
THE QUIETEST PERIOD OF THE SHORT TERM IS EXPECTED TO BE THE DAY
TODAY. THE AREA CONTINUES TO BE SHROUDED IN CLOUD COVER EARLY THIS
MORNING. THE CLEARING LINE...NOW ACROSS ERN WISCONSIN...IS
EXPECTED TO MOVE ACROSS THE AREA THIS MORNING. FAR WESTERN AREAS
COULD SEE SOME FOG DEVELOP IF IT CLEARS OUT EARLY ENOUGH BEFORE
DAYBREAK. WE DO NOT EXPECT THERE WILL BE ENOUGH TIME FOR THE FOG TO
BECOME A PROBLEM.
WE SHOULD SEE A DECENT AMOUNT OF SUNSHINE DURING THE DAY TODAY
WITH SOME MID/HIGH CLOUDS FLOATING ACROSS THE AREA. LATE IN THE
DAY ACROSS THE FAR SOUTH...WE WILL BEGIN TO SEE AN INFLUX OF
MOISTURE AS WAA/ISENTROPIC ASCENT INCREASES WITH THE APPROACH OF
THE STALLED OUT FRONT TO OUR SOUTH. WE MAY SEE JUST ENOUGH MOISTURE
ADVECTION FOR A LOW CHC OF A FEW SHOWERS/STORM LATE ACROSS THE SRN
COUNTIES. H850 TEMPS OF AROUND 10 TO 12C SUPPORT HIGHS IN THE 70S.
THE WARM AND MOIST ADVECTION WILL CONTINUE INTO TONIGHT AS THE LOW
LEVEL JET NOSES IN FROM THE SW LATER TONIGHT. WE EXPECT TO SEE THE
BEST THREAT OF SHOWERS/STORMS ACROSS THE SRN HALF OF THE CWFA
DURING THE LAST HALF OF THE NIGHT TONIGHT. MOISTURE TRANSPORT IS
FCST TO SPREAD ACROSS THE ENTIRE AREA...SO A CHC/SCT
SHOWERS/STORMS WILL BE EXPECTED EVEN NORTH. THIN CAPE PROFILES AND
THE ELEVATED NATURE OF THE STORMS SHOULD LIMIT SEVERE
POTENTIAL...EVEN WITH BULK SHEAR VALUES AROUND 25-35 KNOTS.
CONVECTION WILL STILL LIKELY BE AROUND THE AREA FIRST THING WED
MORNING. MODELS INDICATE THAT THE SFC WAVE MOVING NW OF THE AREA
SHOULD DRAW THE FRONT TO THE NORTH OF THE CWFA IN THE AFTERNOON.
THE SURGE OF MOISTURE TRANSPORT WILL PULL OUT IN THE AFTERNOON...
AND WE COULD SEE CLEARING TAKE PLACE AS WE GET INTO THE WARM
SECTOR. IF THIS WAS TO OCCUR...WE WOULD EASILY SEE TEMPS HIT 80 AT
INLAND LOCATIONS. CONVECTION CHCS LOOK TO DECREASE AS THE
ATMOSPHERE LOOKS TO BECOME CAPPED. STILL NOT IMPOSSIBLE TO SEE
ANOTHER WAVE MOVE THROUGH HOWEVER...SO WE KEPT A CHC IN DURING THE
AFTERNOON.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 345 AM EDT TUE MAY 1 2012
CONVECTION IS EXPECTED TO SOME EXTENT EACH DAY. THE GREATEST CHANCE
FOR STRONG STORMS IS WEDNESDAY NIGHT AND THURSDAY NIGHT (WHEN
THE LOW LEVEL IS CLOSEST). TEMPERATURES WILL UNSEASONABLY WARM INTO
FRIDAY THEN COOL OFF SOME INTO THE WEEKEND.
OVER THE PAST FEW DAYS WE HAVE BEEN WATCHING HOW THE POLAR JET
MIGRATES NORTHWARD INTO SOUTHERN CANADA THE SECOND HALF OF THIS
WEEK INTO THE WEEKEND. THAT IS THE RESULT OF THE WESTERN TROUGH
DEEPENING AND BUILDING AN UPSTREAM RIDGE OVER THE CENTRAL CONUS.
THE FARTHER NORTH THE JET GETS THE LESS LIKELY IS STRONG CONVECTION
HERE. THAT IS MOSTLY DUE TO THE LACK OF DEEP LAYERED SHEAR. THE
MODELS ARE ALL IN GOOD AGREEMENT THAT FEATURE OF THE FORECAST.
THE REAL FORECAST PROBLEMS COME IN OVER THE WEEKEND AS THE ECMWF
CONTINUES TO KEEP THE UPPER LOW OVER NE CANADA OVER NE CANADA WHILE
THE GFS CONTINUES TO DIG THE FEATURE SOUTH SOUTHEAST TOWARD NEW
ENGLAND BY LATE IN THE WEEKEND. THE END RESULT IS THE ECMWF KEEPS
THE FRONT NEAR SOUTHWEST MICHIGAN THROUGH THE WEEKEND WHICH IN TURN
KEEPS THE THREAT FOR CONVECTION EACH DAY. MEANWHILE WITH THE GFS
BRINGING THE UPPER LOW SOUTH SOUTHEAST IT ALSO BRINGS CANADIAN POLAR
AIR SOUTH INTO THE GREAT LAKES SATURDAY NIGHT INTO SUNDAY. THAT OF
COURSE DRIES OUT THE AIR AND ENDS THE RISK FOR CONVECTION BY
SATURDAY NIGHT. I AM SIDING WITH THE ECMWF HERE.
THE LOW LEVEL JET MOVES THROUGH SOUTHWEST MICHIGAN THURSDAY NIGHT
INTO FRIDAY MORNING. THAT IS WHEN THERE SHOULD BE THE GREATEST
THREAT FOR THUNDERSTORMS FOR SOUTHWEST LOWER MICHIGAN. HOWEVER WITH
THE UPPER JET WELL NORTH IN CANADA...THESE STORMS SHOULD NOT BE ALL
THAT STRONG. OVER THE WEEKEND I AM LEANING TOWARD THE ECMWF INTO THE
WEEKEND BUT DUE TO INCREASING UNCERTAINLY WE HAVE LOWER POPS
SATURDAY AND SUNDAY.
WITH THE POLAR JET SO FAR NORTH AND THE SURFACE FRONT NORTH OF
SOUTHWEST LOWER MICHIGAN THURSDAY... IT SHOULD BE VERY WARM. LOW
LEVEL THICKNESS TOOLS SUPPORT HIGHS IN THE MID 80S... EVEN WITH A
FEW CLOUDS AND SHOWERS AROUND. THE FRONT SAGS SOUTH FRIDAY AND
STALLS SATURDAY... DUE TO CLOSENESS OF THE FRONT HIGHS WILL ONLY BE
IN THE 70S FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 0800 AM EDT TUE MAY 1 2012
USING OUR TIMINIG TOOL AND THE NAM12 950 TO 900 MB RH IT SEEMS THE
LOW CLOUDS WILL BREAK UP IN THE 15Z TIME FRAME. HOWEVER NO SOONER
DOES THAT HAPPEN THEN THE MCV TO OUR SW COMES INTO OUR CWA
SOUTHERN CWA BY 21Z OR SO. THE THUNDER SHOULD STAY SOUTH THIS
AFTERNOON.
SHOULD BE MVFR CIGS/VSBY OVERNIGHT AS THE WARM FRONT PUSHES NORTH
WITH HIGHER SURFACE DEW POINT AIR. ALSO THE LOW LEVEL JET NOSES IN
AFTER 06Z SO THAT COULD SET OFF ANOTHER ROUND OF CONVECTION. DUE
TO UNCERTAINTY I DID NOT PUT SHOWERS IN TAFS.
&&
.MARINE...
ISSUED AT 1240 PM EDT TUE MAY 1 2012
SOUTH WINDS WILL REMAIN UNDER 20 KNOTS SO NOT MUCH IMPACT TO
MARINERS EXPECTED FOR THE NEXT FEW DAYS. THERE WILL BE SOME
THUNDERSTORMS THAT WILL POSE A RISK TO MARINERS
&&
.HYDROLOGY...
ISSUED AT 345 AM EDT TUE MAY 1 2012
A FAIRLY MOISTURE RICH AIR MASS WILL MOVE IN BEGINNING LATE TODAY
AND ESPECIALLY TONIGHT. PRECIPITABLE WATER IS EXPECTED TO INCREASE
TO 1.25 TO 1.50 INCHES TONIGHT. THIS AIR MASS SHOULD REMAIN IN
PLACE THROUGH THE REMAINDER OF THE WEEK AND INTO THE WEEKEND. THIS
WILL ALLOW FOR LOCALLY HEAVY RAINFALL TO OCCUR WITH ANY
SHOWERS/STORMS. WE SHOULD NOT HAVE ANY ISSUES WITH THIS. THE ONLY
ISSUE THAT COULD ARISE WOULD BE IF WAVES OF SHOWERS/STORMS START
ROLLING OVER THE SAME AREAS DURING THE NEXT FEW DAYS. THE TRACK OF
ANY SHOWERS/STORMS IS QUITE UNCERTAIN AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...MJS
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...NJJ
MARINE...MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
801 AM EDT TUE MAY 1 2012
.SYNOPSIS...
ISSUED AT 345 AM EDT TUE MAY 1 2012
A MAINLY QUIET DAY IS EXPECTED FOR TODAY AS A FRONTAL SYSTEM
REMAINS SOUTH OF THE AREA THROUGH THE DAY. THE CHANCE OF SHOWERS
AND STORMS WILL GRADUALLY INCREASE LATE THIS AFTERNOON THROUGH
WEDNESDAY MORNING AS THE FRONT LIFTS NORTH ACROSS THE STATE. WE
WILL THEN SEE CHANCES FOR SHOWERS AND STORMS THROUGH THE WEEKEND
WITH WARM WEATHER HOLDING IN THROUGH THEN.
&&
.UPDATE...
ISSUED AT 800 AM EDT TUE MAY 1 2012
I HAVE NOTED THE MCV OVER MO HEADING NORTHEAST TOWARD SOUTHERN
LOWER MICHIGAN BY LATE AFTERNOON. THE HRRR AND RUC SEEM TO LIKE
THE FEATURE AND THE RUC SHOWS A 40 KNOT LLJ INTO CNTL IL BY 18Z.
THE HRRR KEEPS THE ACTUAL THUNDERSTORMS NEAR AND SOUTH OF I-80 BUT
BRINGS RAIN SOUTH OF I-96 BY 20Z. SO AFTER TALKING WITH IWX SHORT
TERM... WE DECIDED TO GO AHEAD AND BRING THE CONVECTION IN MID TO
LATE AFTERNOON. THE UPDATED GRIDS AND ZONES HAVE BEEN ISSUED
ALREADY.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 345 AM EDT TUE MAY 1 2012
THE MAIN FORECAST CHALLENGE THROUGH THE SHORT TERM WILL BE
DETERMINING CONVECTIVE TRENDS THROUGH THE PERIOD AS A FRONTAL
SYSTEM WILL RESIDE ACROSS THE REGION THROUGH THE PERIOD.
THE QUIETEST PERIOD OF THE SHORT TERM IS EXPECTED TO BE THE DAY
TODAY. THE AREA CONTINUES TO BE SHROUDED IN CLOUD COVER EARLY THIS
MORNING. THE CLEARING LINE...NOW ACROSS ERN WISCONSIN...IS
EXPECTED TO MOVE ACROSS THE AREA THIS MORNING. FAR WESTERN AREAS
COULD SEE SOME FOG DEVELOP IF IT CLEARS OUT EARLY ENOUGH BEFORE
DAYBREAK. WE DO NOT EXPECT THERE WILL BE ENOUGH TIME FOR THE FOG TO
BECOME A PROBLEM.
WE SHOULD SEE A DECENT AMOUNT OF SUNSHINE DURING THE DAY TODAY
WITH SOME MID/HIGH CLOUDS FLOATING ACROSS THE AREA. LATE IN THE
DAY ACROSS THE FAR SOUTH...WE WILL BEGIN TO SEE AN INFLUX OF
MOISTURE AS WAA/ISENTROPIC ASCENT INCREASES WITH THE APPROACH OF
THE STALLED OUT FRONT TO OUR SOUTH. WE MAY SEE JUST ENOUGH MOISTURE
ADVECTION FOR A LOW CHC OF A FEW SHOWERS/STORM LATE ACROSS THE SRN
COUNTIES. H850 TEMPS OF AROUND 10 TO 12C SUPPORT HIGHS IN THE 70S.
THE WARM AND MOIST ADVECTION WILL CONTINUE INTO TONIGHT AS THE LOW
LEVEL JET NOSES IN FROM THE SW LATER TONIGHT. WE EXPECT TO SEE THE
BEST THREAT OF SHOWERS/STORMS ACROSS THE SRN HALF OF THE CWFA
DURING THE LAST HALF OF THE NIGHT TONIGHT. MOISTURE TRANSPORT IS
FCST TO SPREAD ACROSS THE ENTIRE AREA...SO A CHC/SCT
SHOWERS/STORMS WILL BE EXPECTED EVEN NORTH. THIN CAPE PROFILES AND
THE ELEVATED NATURE OF THE STORMS SHOULD LIMIT SEVERE
POTENTIAL...EVEN WITH BULK SHEAR VALUES AROUND 25-35 KNOTS.
CONVECTION WILL STILL LIKELY BE AROUND THE AREA FIRST THING WED
MORNING. MODELS INDICATE THAT THE SFC WAVE MOVING NW OF THE AREA
SHOULD DRAW THE FRONT TO THE NORTH OF THE CWFA IN THE AFTERNOON.
THE SURGE OF MOISTURE TRANSPORT WILL PULL OUT IN THE AFTERNOON...
AND WE COULD SEE CLEARING TAKE PLACE AS WE GET INTO THE WARM
SECTOR. IF THIS WAS TO OCCUR...WE WOULD EASILY SEE TEMPS HIT 80 AT
INLAND LOCATIONS. CONVECTION CHCS LOOK TO DECREASE AS THE
ATMOSPHERE LOOKS TO BECOME CAPPED. STILL NOT IMPOSSIBLE TO SEE
ANOTHER WAVE MOVE THROUGH HOWEVER...SO WE KEPT A CHC IN DURING THE
AFTERNOON.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 345 AM EDT TUE MAY 1 2012
CONVECTION IS EXPECTED TO SOME EXTENT EACH DAY. THE GREATEST CHANCE
FOR STRONG STORMS IS WEDNESDAY NIGHT AND THURSDAY NIGHT (WHEN
THE LOW LEVEL IS CLOSEST). TEMPERATURES WILL UNSEASONABLY WARM INTO
FRIDAY THEN COOL OFF SOME INTO THE WEEKEND.
OVER THE PAST FEW DAYS WE HAVE BEEN WATCHING HOW THE POLAR JET
MIGRATES NORTHWARD INTO SOUTHERN CANADA THE SECOND HALF OF THIS
WEEK INTO THE WEEKEND. THAT IS THE RESULT OF THE WESTERN TROUGH
DEEPENING AND BUILDING AN UPSTREAM RIDGE OVER THE CENTRAL CONUS.
THE FARTHER NORTH THE JET GETS THE LESS LIKELY IS STRONG CONVECTION
HERE. THAT IS MOSTLY DUE TO THE LACK OF DEEP LAYERED SHEAR. THE
MODELS ARE ALL IN GOOD AGREEMENT THAT FEATURE OF THE FORECAST.
THE REAL FORECAST PROBLEMS COME IN OVER THE WEEKEND AS THE ECMWF
CONTINUES TO KEEP THE UPPER LOW OVER NE CANADA OVER NE CANADA WHILE
THE GFS CONTINUES TO DIG THE FEATURE SOUTH SOUTHEAST TOWARD NEW
ENGLAND BY LATE IN THE WEEKEND. THE END RESULT IS THE ECMWF KEEPS
THE FRONT NEAR SOUTHWEST MICHIGAN THROUGH THE WEEKEND WHICH IN TURN
KEEPS THE THREAT FOR CONVECTION EACH DAY. MEANWHILE WITH THE GFS
BRINGING THE UPPER LOW SOUTH SOUTHEAST IT ALSO BRINGS CANADIAN POLAR
AIR SOUTH INTO THE GREAT LAKES SATURDAY NIGHT INTO SUNDAY. THAT OF
COURSE DRIES OUT THE AIR AND ENDS THE RISK FOR CONVECTION BY
SATURDAY NIGHT. I AM SIDING WITH THE ECMWF HERE.
THE LOW LEVEL JET MOVES THROUGH SOUTHWEST MICHIGAN THURSDAY NIGHT
INTO FRIDAY MORNING. THAT IS WHEN THERE SHOULD BE THE GREATEST
THREAT FOR THUNDERSTORMS FOR SOUTHWEST LOWER MICHIGAN. HOWEVER WITH
THE UPPER JET WELL NORTH IN CANADA...THESE STORMS SHOULD NOT BE ALL
THAT STRONG. OVER THE WEEKEND I AM LEANING TOWARD THE ECMWF INTO THE
WEEKEND BUT DUE TO INCREASING UNCERTAINLY WE HAVE LOWER POPS
SATURDAY AND SUNDAY.
WITH THE POLAR JET SO FAR NORTH AND THE SURFACE FRONT NORTH OF
SOUTHWEST LOWER MICHIGAN THURSDAY... IT SHOULD BE VERY WARM. LOW
LEVEL THICKNESS TOOLS SUPPORT HIGHS IN THE MID 80S... EVEN WITH A
FEW CLOUDS AND SHOWERS AROUND. THE FRONT SAGS SOUTH FRIDAY AND
STALLS SATURDAY... DUE TO CLOSENESS OF THE FRONT HIGHS WILL ONLY BE
IN THE 70S FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 0800 AM EDT TUE MAY 1 2012
USING OUR TIMINIG TOOL AND THE NAM12 950 TO 900 MB RH IT SEEMS THE
LOW CLOUDS WILL BREAK UP IN THE 15Z TIME FRAME. HOWEVER NO SOONER
DOES THAT HAPPEN THEN THE MCV TO OUR SW COMES INTO OUR CWA
SOUTHERN CWA BY 21Z OR SO. THE THUNDER SHOULD STAY SOUTH THIS
AFTERNOON.
SHOULD BE MVFR CIGS/VSBY OVERNIGHT AS THE WARM FRONT PUSHES NORTH
WITH HIGHER SURFACE DEW POINT AIR. ALSO THE LOW LEVEL JET NOSES IN
AFTER 06Z SO THAT COULD SET OFF ANOTHER ROUND OF CONVECTION. DUE
TO UNCERTAINTY I DID NOT PUT SHOWERS IN TAFS.
&&
.MARINE...
ISSUED AT 345 AM EDT TUE MAY 1 2012
WINDS WILL REMAIN BELOW 20 KNOTS THROUGH MOST OF TONIGHT ACROSS
THE NEARSHORE WATERS. WINDS MAY COME UP TO AROUND 20 KNOTS LATE
TONIGHT AND ON WEDNESDAY AS SOME STRONGER WINDS COME IN WITH THE
NEXT WAVE. MOST OF THIS WIND SHOULD REMAIN WELL ABOVE THE SURFACE
SINCE WARMER AIR WILL BE MOVING IN OVER THE COOLER LAKE WATERS.
ANOTHER CORE OF WINDS WILL ARRIVE LATE THURSDAY AND THURSDAY NIGHT.
&&
.HYDROLOGY...
ISSUED AT 345 AM EDT TUE MAY 1 2012
A FAIRLY MOISTURE RICH AIR MASS WILL MOVE IN BEGINNING LATE TODAY
AND ESPECIALLY TONIGHT. PRECIPITABLE WATER IS EXPECTED TO INCREASE
TO 1.25 TO 1.50 INCHES TONIGHT. THIS AIR MASS SHOULD REMAIN IN
PLACE THROUGH THE REMAINDER OF THE WEEK AND INTO THE WEEKEND. THIS
WILL ALLOW FOR LOCALLY HEAVY RAINFALL TO OCCUR WITH ANY
SHOWERS/STORMS. WE SHOULD NOT HAVE ANY ISSUES WITH THIS. THE ONLY
ISSUE THAT COULD ARISE WOULD BE IF WAVES OF SHOWERS/STORMS START
ROLLING OVER THE SAME AREAS DURING THE NEXT FEW DAYS. THE TRACK OF
ANY SHOWERS/STORMS IS QUITE UNCERTAIN AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...WDM
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...NJJ
MARINE...NJJ
AREA FORECAST DISCUSSION
NWS HASTINGS NE
649 PM CDT WED MAY 2 2012
.AVIATION...00Z KGRI TAF. THE PRIMARY AVIATION CONCERN WILL
CONTINUE TO CENTER AROUND THUNDERSTORM CHANCES LATE THIS EVENING
INTO THE EARLY MORNING HOURS. THUNDERSTORMS ARE EXPECTED TO
DEVELOP AND EXPAND ACROSS SOUTH CENTRAL NEBRASKA AS THE LOW LEVEL
JET INCREASES IN STRENGTH AFTER SUNSET. A FEW OF THESE
THUNDERSTORMS MAY IMPACT THE KGRI AREA. THE WIND WILL GENERALLY BE
LIGHT AT KGRI WHEN THUNDERSTORMS ARE NOT ONGOING...BUT COULD
BECOME VERY GUSTY AND EVEN SEVERE SHOULD ONE OF THE STRONGER
STORMS MOVE ACROSS KGRI.
&&
.PREV DISCUSSION... /ISSUED 345 PM CDT WED MAY 2 2012/
SHORT TERM...THROUGH 00Z FRIDAY. MORNING UPPER AIR ANALYSIS INDICATES
QUASI-ZONAL MID AND UPPER LEVEL FLOW ACROSS MUCH OF THE CENTRAL
CONUS...WITH A MID LEVEL SHORTWAVE TROUGH NOTED OVER THE
NORTHWESTERN CONUS. MID AND UPPER LEVEL JET ENERGY REMAINS
RELEGATED TO THE WEST/NORTHWESTERN CONUS...WITH TROPOSPHERIC FLOW
REMAINING FAIRLY LIGHT OVER OUR AREA. WATER VAPOR IMAGERY
INDICATES A PLUME OF MID LEVEL MOISTURE ADVANCING FROM THE PACIFIC
INTO THE SOUTHWESTERN CONUS...ONWARD INTO THE MIDDLE ROCKY
MOUNTAIN RANGE AS WELL AS PORTIONS OF THE CENTRAL AND NORTHERN
PLAINS. EARLY AFTERNOON SURFACE ANALYSIS SHOWS AN AREA OF LOW
PRESSURE OVER SOUTHWESTERN KANSAS...WITH A WARM FRONT EXTENDING
NORTHEASTWARD FROM THE LOW INTO PORTIONS OF NORTH CENTRAL KANSAS
AS WELL AS PORTIONS OF SOUTH CENTRAL AND SOUTHEAST NEBRASKA. AS OF
18Z THIS WARM FRONT WAS NOTED EXTENDING FROM NEAR KHYS...TO NEAR
KK82...TO NEAR KJYR AND KOLU. EARLY AFTERNOON TEMPERATURES ARE
GENERALLY IN THE UPPER 70S AND LOWER 80S ACROSS THE CWA...WITH DEW
POINTS RANGING FROM THE MID 40S AT KLXN...TO THE UPPER 50S THROUGH
THE TRI-CITIES...TO THE MID AND UPPER 60S ACROSS OUR SOUTHEAST
WHERE THE SURFACE WARM FRONT HAS ALREADY CLEARED. EARLY AFTERNOON
VISIBLE SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES ACROSS OUR
NORTHWESTERN CWA...WITH THE INCREASED LOW LEVEL MOISTURE VALUES
HELPING PROMOTE INCREASED INSTABILITY AND A RESULTANT EXPANSIVE CU
FIELD.
FOR THE REST OF THIS AFTERNOON AND EARLY THIS EVENING...CONFIDENCE
IS LOW REGARDING CONVECTIVE DEVELOPMENT ACROSS OUR AREA AS FORECAST
PROXIMITY SOUNDINGS FROM THE NAM AND OPERATIONAL GFS SUGGEST
CONVECTIVE INHIBITION SHOULD HOLD FOR THE MOST PART. THAT BEING
SAID...FORECAST PROXIMITY SOUNDINGS FROM THE NAM DO SUGGEST CIN WILL
DECREASE TO ALMOST NOTHING ACROSS OUR EXTREME SOUTHEAST BY 00Z THIS
EVENING...AND WITH THE LOW LEVEL BAROCLINIC ZONE MEANDERING ACROSS
THE AREA THUS PROMOTING LOW LEVEL CONVERGENCE AND RESULTANT
FORCING...FELT IT PRUDENT TO GO WITH A SLIGHT CHANCE POP ACROSS THE
ENTIRE CWA LATE THIS AFTERNOON THROUGH THIS EVENING. THE NAM AND
OPERATIONAL GFS SUGGEST 0-1KM MLCAPE VALUES OF 2000-3500J/KG WILL BE
OBSERVED ACROSS OUR CWA LATE THIS AFTERNOON AND EVENING...WITH THE
GREATEST INSTABILITY LOCATED ACROSS OUR SOUTHEAST WITHIN THE LOW
LEVEL MOISTURE PLUME. WITH MID AND UPPER LEVEL JET ENERGY REMAINING
RELEGATED TO THE WEST/NORTHWEST OF OUR AREA...DEEP LAYER BULK SHEAR IS
NOT OVERLY IMPRESSIVE...BUT GUIDANCE DOES SUGGEST DEEP LAYER BULK
SHEAR VALUES NEAR 30KTS WILL STILL BE POSSIBLE THUS PRESENTING THE
POSSIBILITY FOR ROTATING UPDRAFTS. ALL THAT BEING SAID...SHOULD
CONVECTIVE INITIATION BE REALIZED LATE THIS AFTERNOON OR EARLY THIS
EVENING...SEVERE WEATHER WILL MOST LIKELY BE OBSERVED WITH LARGE
HAIL BEING THE PRIMARY THREAT...AND ISOLATED THUNDERSTORM WIND GUSTS
ALSO POSSIBLE ALONG OUTFLOW. FINALLY...0-1KM SRH IS NOT OVERLY
IMPRESSIVE...WITH THE NAM AND OPERATIONAL GFS SUGGESTING VALUES
SOMEWHERE AROUND 100 M^2/S^2 ACROSS OUR AREA AT 00Z...BUT WITH
LOCALLY ENHANCED LOW LEVEL HORIZONTAL VORTICITY EXISTING IN THE
VICINITY OF LOW LEVEL BAROCLINIC ZONE...ISOLATED TORNADOES ALSO
CANNOT BE RULED OUT.
ATTENTION THEN TURNS TO THE SEVERE POTENTIAL OVERNIGHT TONIGHT. THE
NAM...OPERATIONAL GFS...EC...SREF-MEAN AND HRRR ALL SUGGEST
AFTERNOON AND EVENING HIGH PLAINS CONVECTION WILL MORPH INTO A MCS
AND PUSH EAST INTO PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH
CENTRAL KANSAS. AS THE MCS PUSHES EAST IT SHOULD BEGIN INTERACTING
WITH A 40-50KT LOW LEVEL JET WHICH SHOULD HELP SUSTAIN THE MCS IF
NOT HELP IT INTENSIFY THROUGH INCREASED LOW LEVEL MOISTURE FLUX.
GIVEN ALL THIS...A WIDESPREAD SEVERE STRAIGHT LINE WIND EVENT
SOMEWHERE ACROSS OUR CWA IS APPEARING MORE AND MORE LIKELY OVERNIGHT
TONIGHT. AS IS USUALLY THE CASE...EXACT DETAILS REGARDING PLACEMENT AND
TRACK OF THIS MCS WILL NOT LIKELY BE KNOWN UNTIL LATER THIS
EVENING...BUT GIVEN THE LATEST DATA WILL GO AHEAD AND HIGHLIGHT MOST
ALL OF THE CWA FOR SEVERE OVERNIGHT TONIGHT...WITH STRAIGHT LINE
WINDS BEING THE PRIMARY SEVERE WEATHER THREAT. ONE ADDITIONAL
NOTE...THE AFOREMENTIONED MID LEVEL MOISTURE PLUME NOTED ON WATER
VAPOR IMAGERY SHOULD PUSH OVERHEAD TONIGHT THUS HELPING TO INCREASE
PRECIPITABLE WATER VALUES. THESE INCREASING MID LEVEL MOISTURE
VALUES...ALONG WITH THE STRONG CONVECTION CURRENTLY FORECAST...WILL
HAVE THE CAPABILITY TO PROMOTE HEAVY RAINFALL AND PERHAPS LOCALIZED
FLASH FLOODING.
PRECIPITATION CHANCES FOR THURSDAY REMAIN UNCERTAIN AT THIS
POINT...ESPECIALLY WITH THE POTENTIAL FOR A SIGNIFICANT MESO-HIGH
SETTING UP OVER THE AREA DUE TO OVERNIGHT RAIN. ASSUMING THE MESO-HIGH
CAN FULLY DISSIPATE BY MID TO LATE AFTERNOON...AND ASSUMING THERE
IS ENOUGH OMEGA WITH ONE OF THE MANY MID LEVEL PERTURBATIONS WHICH
WILL BE PUSHING OVER THE AREA ALONG THE APPROACHING MID LEVEL JET
AXIS...THURSDAY AFTERNOON 0-1KM MLCAPE VALUES ON THE ORDER OF
1000-2500J/KG COULD CERTAINLY PROMOTE A SEVERE HAIL THREAT. AT
THIS TIME IT APPEARS THE BEST POTENTIAL FOR OBSERVING SEVERE
WEATHER ON THURSDAY WILL BE RELEGATED TO OUR EAST WITHIN THE
BETTER LOW LEVEL MOISTURE...AND WILL GO AHEAD AND HIGHLIGHT OUR
EAST FOR SEVERE WEATHER ON THURSDAY AS A RESULT.
LONG TERM...STARTING WITH THE MID-TERM THURSDAY EVENING THROUGH
SATURDAY PERIOD...THE RISK OF THUNDERSTORMS...OR LACK
THEREOF...CONTINUES TO BE THE ULTIMATE DILEMMA DURING THESE 48
HOURS AND CONFIDENCE IN THE DETAILS CONTINUES TO RUN BELOW
AVERAGE. ALOFT...A BLEND OF SOLUTIONS FROM THE 12Z NAM/GFS AND 00Z
ECMWF CONTINUE TO ADVERTISE A RATHER PERSISTENT PATTERN...AS
MODESTLY STRONG...BROAD WEST-SOUTHWEST FLOW REMAINS IN
PLACE...DOWNSTREAM FROM A LARGER SCALE SHORTWAVE TROUGH THAT
CARVES OUT ACROSS THE PACIFIC NORTHWEST/NORTHERN ROCKIES. THE
PRIMARY 300MB JET AXIS WILL THUS REMAIN OFF TO THE NORTH AND WEST
OF THE REGION. HOWEVER...CONSIDERABLE CONVECTIVE INSTABILITY WILL
REMAIN FIRMLY IN PLACE IN OR NEAR THE CWA...AS A QUASI-STATIONARY
FRONT WAVERS BACK AND FORTH ACROSS THE GENERAL REGION. BEFORE
CONTINUING...WILL AGAIN STATE THAT CONFIDENCE IN THE DETAILS IS
LOW REGARDING POPS/THUNDER/SEVERE CHANCES...WITH A BIT HIGHER
CONFIDENCE IN TEMPS. HOWEVER...WAS NO LONGER WILLING TO LEAVE THE
FRIDAY THROUGH SATURDAY TIME FRAME COMPLETELY VOID OF ANY
THUNDERSTORM MENTION.
STARTING WITH THURSDAY EVENING/NIGHT...DECIDED TO BLANKET A GENERIC
20 PERCENT CHANCE OF STORMS CWA-WIDE...AS JUST CANNOT GUARANTEE A
STORM-FREE NIGHT ANYWHERE. DETERMINISTIC MODELS ARE ALL OVER THE
PLACE ON QPF PLACEMENT...WITH THE ECWMF ROLLING STORMS IN FROM THE
WEST MAINLY IN THE EVENING...WHILE THE NAM/GFS AFFECT AT LEAST
SOUTHWEST PORTIONS OF THE AREA MAINLY AFTER 06Z. LEANING ON THE 12Z
NAM...ONLY A MODEST LOW LEVEL JET IS PRESENT OVERNIGHT...BUT WITH
SUBTLE SHORTWAVES MOVING THROUGH AND HEALTHY ELEVATED MUCAPE IN
EXCESS OF 2500 J/KG HANGING OUT ACROSS MOST OF THE CWA THROUGH THE
NIGHT...JUST FEEL BETTER HAVING A TOKEN 20 PERCENT CHANCE
EVERYWHERE. HOWEVER...IT IS LIKELY THAT MOST OF THE AREA WILL IN
FACT REMAIN STORM FREE...WITH THE MOST LIKELY SCENARIO FOR POSSIBLE
CONVECTION BEING HIGH PLAINS ACTIVITY DRIFTING IN FROM THE WEST. AS
FOR SEVERE CHANCES THURSDAY NIGHT...DEEP LAYER SHEAR IS NOT ALL THAT
STRONG...20-30 KNOTS AT MOST...BUT OBVIOUSLY WITH HIGH CAPE LEVELS
HANGING AROUND CANNOT RULE OUT AT LEAST MARGINALLY SEVERE HAIL AND
WIND. AS FOR LOW TEMPS...NUDGED UP SLIGHTLY FROM PREVIOUS
FORECAST...WITH MOST OF SOUTHEAST 1/2 OF CWA HOLDING UP IN THE
LOW-MID 60S.
FOR FRIDAY...MUCH OF THE SAME...AS FORCING ALOFT REMAINS
SUBTLE...BUT INSTABILITY REMAINS HIGH WITH AFTERNOON MLCAPE VALUES
AGAIN BUILDING TO AROUND 3000 J/KG OR HIGHER PER THE NAM...ALTHOUGH
THIS MODEL MAY BE OVERDOING DEWPOINTS AND RESULTANT CAPE A BIT.
ALTHOUGH ODDS ARE REASONABLY HIGH THAT MOST OF THE AREA WILL REMAIN
STORM FREE...OPTED TO INTRODUCE A SLIGHT 20 POP ACROSS SEVERAL
COUNTIES NORTH OF I-80...AS HINTED AT BY THE 12Z GFS AND TO A LESSER
EXTENT THE 12Z NAM. AGAIN...ANYTHING THAT HAPPENS TO FIRE IN THIS
AREA BEFORE DARK COULD POTENTIALLY BE SEVERE. TEMP WISE...ASSUMING
THAT SOUTHERLY BREEZES ARE PRESENT AND CLOUDS ARE NOT
WIDESPREAD...THIS HAS THE POTENTIAL TO BE A RATHER WARM DAY.
ALTHOUGH STILL NOT AIMING QUITE AS HIGH AS THE NAM SUGGESTS...NUDGED
UP A FEW DEGREES...NOW PUTTING MOST OF THE CWA IN THE 87-90 RANGE.
FRIDAY NIGHT...INTRODUCED MORE SLIGHT THUNDERSTORM CHANCES MAINLY
NORTH OF I-80 IN CLOSEST PROXIMITY TO TRACK OF SUBTLE
SHORTWAVES...AND IN THE PRESENCE OF CONTINUED HEALTHY ELEVATED
INSTABILITY. FOR THE DAYTIME HOURS SATURDAY...JUST CONTINUED WITH
MORE OF THE SAME...KEEPING THE SAME AREAS NORTH OF INTERSTATE 80 IN
A SLIGHT CHANCE OF STORMS...BUT WITH BETTER FOCUS LIKELY TARGETING
AREAS JUST TO THE NORTH. BY THIS TIME...THE PRIMARY MID LEVEL TROUGH
TO THE WEST WILL BE CENTERED ROUGHLY ALONG A MT-UT AXIS...BUT STILL
WELL TO THE WEST. TEMP WISE SATURDAY...KEPT SUMMER-LIKE READINGS
GOING AND EVEN NUDGED UP A FEW DEGREES FROM PREVIOUS PER MODEL
CONSENSUS...WITH MID-UPPER 80S MOST AREAS...AND SOME LOW 90S MOST
FAVORED IN KS ZONES.
FOCUSING NOW ON THE LONGER TERM PERIODS SATURDAY NIGHT THROUGH
NEXT WEDNESDAY: IN SHORT...EACH AND EVERY PERIOD FEATURES AT LEAST
20-30 PERCENT RAIN CHANCES FOR NOW...ALTHOUGH WILL STATE THE OBVIOUS
THAT SOME OF THESE PERIODS WILL LIKELY END UP BEING DRY...WITH
PLENTY OF TWEAKING LIKELY OVER THE NEXT SEVERAL DAYS. LOOKING AT THE
BIG PICTURE AND LEANING TOWARD A BLEND OF THE 12Z ECMWF/GFS...THERE
IS ACTUALLY REASONABLY HIGH AGREEMENT THAT ON SATURDAY NIGHT AND
SUNDAY NIGHT A FAIRLY WELL DEFINED SURFACE COLD FRONT WILL CROSS THE
AREA...DRIVEN SOUTHWARD IN RESPONSE TO THE AFOREMENTIONED MID LEVEL
SHORTWAVE TROUGH RIDING UP ACROSS THE NORTHERN PLAINS INTO SOUTH
CENTRAL CANADA. AS A RESULT OF THIS FRONTAL PASSAGE...THE HIGHEST
POPS IN THE EXTENDED PERIOD...40S-50S PERCENTS ACROSS MAINLY NEB
ZONES FOR NOW...ARE FOCUSED ON SATURDAY NIGHT. ALTHOUGH DEEP LAYER
WIND SHEAR DOES NOT LOOK OVERLY IMPRESSIVE WITH THIS FRONTAL
PASSAGE...THE GFS HAS MUCAPE VALUES OF AT LEAST 2000-3000 J/KG IN
PLACE DURING THIS TIME FRAME...SO CERTAINLY A SLIGHT RISK OF SEVERE
NOT OUT OF THE QUESTION. IN THE WAKE OF THIS BOUNDARY...TEMPS SUNDAY
ARE CURRENTLY FORECAST ABOUT 10 DEGREES COOLER THAN
SATURDAY...RANGING FROM LOW 70S NORTHWEST TO LOW 80S SOUTHEAST.
BEYOND SUNDAY...THE CURRENTLY ADVERTISED POPS WOULD SEEM TO COME
MORE AND MORE UNDER QUESTION...BUT WILL STICK WITH THEM PER NOW
ACCORDING TO THE ALLBLEND CONSENSUS INITIALIZATION. THE BASIC STORY
INVOLVES A GRADUAL CARVING OUT OF A MID LEVEL TROUGH ACROSS THE
NORTH CENTRAL CONUS...RESULTING IN A NOTICEABLY COOLER TEMP REGIME
THAN THE CURRENT PATTERN. NUDGED DOWN HIGHS SLIGHTLY FOR MONDAY WITH
UPPER 60S-LOW 70S...WHILE TUESDAY CONTINUES TO LOOK LIKE THE COOLEST
DAY OF THE PERIOD WITH HIGHS ONLY MID-UPPER 60S ALL AREAS AND MAYBE
A REBOUND TO NEAR 70 WEDNESDAY. EVEN IF RAIN WERE TO MATERIALIZE
DURING THE MONDAY NIGHT-WEDNESDAY TIME FRAME...HAVE DROPPED THUNDER
MENTION IN THE FORECAST IN FAVOR OF PLAIN SHOWERS...AS MUCAPE PROGS
FROM BOTH THE ECMWF/GFS ADVERTISE VERY LIMITED IF ANY CONVECTIVE
INSTABILITY. IN CLOSING...WANT TO REITERATE THAT ALTHOUGH POPS IN
THE SAT NIGHT-SUNDAY TIME FRAME LOOK QUITE WARRANTED...WOULD EXPECT
TO SEE AN EVENTUAL TRIMMING OF SOME OF THE RAIN CHANCES DURING THE
SUNDAY NIGHT-WEDNESDAY TIME FRAME.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
341 PM CDT TUE MAY 1 2012
.SHORT TERM...TONIGHT THROUGH FRIDAY
GOING FCST IS IN GOOD SHAPE...ONLY MINOR TWEAKS MADE. MAIN CONCERN
THEN CONTINUES TO BE PINNING DOWN AREAL COVERAGE OF SVR STORM
ACTIVITY THIS EVENING. AS OF NOW IT APPEARS THAT THE UPPER MIDWEST
WILL BE PRIME FOR SVR STORMS IN ASSOCIATED WITH LIFTING WARM FRONT...
WITH ANOTHER AREA OF RISK ASSOCIATED WITH COOL FRONT CURRENTLY
DROPPING THRU THE DAKOTAS. HRRR AND RAP SOLUTIONS HAVE BEEN RATHER
CONSISTENT TODAY SUGGESTING LINE OF CONVECTION MOVING INTO THE NRN
CWA BY EARLY EVENING. ESRH AROUND 360 M2/S2 AND MUCAPES 2000 J/KG OR
SO SHOULD BE ENOUGH TO POP SOME SVR MAINLY OVER NORTHEAST NEB.
AMPLIFYING TROF DIG OVER THE WRN CONUS WILL REPLACE THE NEAR-ZONAL
FLOW WITH LOW AMPLITUDE UPPER RIDGE GRADUALLY BUILDING OVER THE
PLAINS. THIS WILL ACT TO HINDER BNDRY PROGRESSION ANY FARTHER SOUTH
AND KEEP IT INVOF THE CWA. ON WEDNESDAY...MUCAPES INCREASE TO 4500
J/KG BY AFTERNOON BUT DEEP LAYER SHEAR IS MORE FOCUSED NORTH. THUS
NORTHEAST NEB MAY BE UNDER THE GUN AGAIN LATE WEDNESDAY
AFTN/EVENING. THURSDAY THROUGH FRIDAY MODELS PROG SEVERAL IMPULSES
EJECTING OUT OF THE SOUTHWESTERN STATES MAY HELP DESTABILIZE ENOUGH
TO POP OFF ADDITIONAL CONVECTION.
DEE
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY
FAIRLY ACTIVE WEATHER PATTERN SHOULD CONTINUE INTO EARLY NEXT WEEK
AS UPPER TROUGH REMAIN TO OUR WEST...EJECTING WAVES OF ENERGY INTO
THE PLAINS.
WARM ADVECTION FRIDAY NIGHT MAY SPARK THUNDERSTORMS OVER THE
NORTHERN CWA...NORTH OF A EAST-WEST WARM FRONT BISECTING OUR AREA.
THOSE SHOULD MOVE ON OFF TO THE NORTHEAST FAIRLY QUICKLY SATURDAY
MORNING...LEAVING OUR CWA IN A VERY UNSTABLE AIRMASS BY SATURDAY
AFTERNOON. CAPPING UNDER WEAK MID LEVEL RIDGE MAY PRECLUDE
DEVELOPMENT MUCH OF THE DAY...MOST LIKELY WAITING FOR LOWERING
HEIGHTS AS RIDGE SLIDES EAST SATURDAY EVENING. THUNDERSTORMS ARE
GOOD BET THEN...ESPECIALLY IN THE NORTH WHERE A COLD FRONT WILL BE
APPROACHING OVERNIGHT.
THAT FRONT WILL DRIFT ACROSS THE AREA SUNDAY...MAINTAINING A FAIRLY
HIGH CHANCE FOR CONTINUING RAIN AND THUNDER. COOLER AIR WILL
FOLLOW...BUT THE CHANCE FOR RAIN OR SHOWERS WILL STILL EXIST AS
MOIST SOUTHWEST FLOW ALOFT RIDES OVER COOL SURFACE LAYER. THIS
PATTERN PERSISTS THROUGH TUESDAY.
TEMPERATURES LOOK WARM SATURDAY WITH SOUTHERLY FLOW AND MORE
HUMIDITY. HAVE HIGHS IN THE 80S THEN. RAIN AND COLD FRONTAL PASSAGE
WILL COOL HIGHS INTO THE 70S SUNDAY...THEN ONLY 60S FOR MONDAY AND
TUESDAY INFLUENCED BY NORTH TO EAST LOW LEVEL WIND COMPONENT.
DERGAN
&&
.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
THUNDERSTORM DEVELOPMENT IS THE PRIMARY CONCERN AT ALL TAF SITES.
BELIEVE THAT A COMPLEX OF STORMS SHOULD DEVELOP ALONG A COLD FRONT
NORTHWEST OF KOFK LATE THIS AFTERNOON...THEN AFFECT THAT SITE FROM
ABOUT 00-04Z...THEN ROLL/DEVELOP EAST SOUTHEAST AND AFFECT KLNK/KOMA
FROM ABOUT 04-09Z. UNTIL THEN...VFR CONDITIONS...WITH SOUTH
SOUTHWEST WINDS AT 16 TO 18 SUSTAINED...WITH GUSTS UP TO 26 TO
28KTS. AFTER THE STORMS MOVE THROUGH...SOME MVFR FOG OR HAZE COULD
DEVELOP FROM ABOUT 09Z-15Z. COULD ALSO SOME SEE SOME LOWER MVFR
STRATO CLOUDS DEVELOPING OVERNIGHT AS WELL.
DEWALD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1257 PM CDT TUE MAY 1 2012
.AVIATION...18Z KGRI TAF. CONFIDENCE IS RATHER LOW CONCERNING SKY
COVER FOR THIS FORECAST. A PATCH OF STRATUS TO THE WEST OF THE
TERMINAL HAS REMAINED WEST FOR THE MOST PART...BUT SEEMS TO BE
RATHER STUBBORN AND SHOWING SIGNS OF EASTWARD MOVEMENT POTENTIAL.
MODELS ARE NOT HANDLING THIS MESOSCALE FEATURE VERY WELL. THE BEST
GUESS IS THAT THESE CEILINGS NEAR 2500 FT WILL REMAIN TO THE WEST
OF THE TERMINAL. THUNDERSTORM POTENTIAL HAS DECREASED TO THE POINT
THAT THESE HAVE BEEN PULLED OUT OF THE FORECAST...WITH ANY
DEVELOPMENT BEING TO THE NORTH AND EAST. MODELS INDICATE THAT
THERE COULD BE A BIT OF A VISIBILITY RESTRICTION LATE TONIGHT INTO
WEDNESDAY MORNING...BUT NOT AS PERVASIVE AS THE PAST COUPLE OF
MORNINGS.
&&
.UPDATE...UPDATED THE FORECAST FOR THIS AFTERNOON TO ACCOUNT FOR
STUBBORN STRATUS IN THE WESTERN CWA AND THICKENING CIRRUS LATER
THIS AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 1036 AM CDT TUE MAY 1 2012/
UPDATE...JUST COMPLETED THE FIRST UPDATE OF THE DAY...ADDRESSING
TWO MAIN TOPICS. FIRST OFF...PULLED ALL MENTION OF FOG...AS
VISIBILITIES HAVE GREATLY IMPROVED...AND MOSTLY CLEAR SKIES NOW
DOMINATE MOST OF THE CWA...EXCEPT FOR STUBBORN LOW STRATUS
HANGING FIRM MAINLY WEST OF AN ORD-BEAVER CITY LINE WHICH SHOULD
ALSO SCATTER OUT EVENTUALLY. SECOND AND OVERALL MORE IMPORTANT
FOCUS WAS THUNDERSTORM CHANCES THROUGH LATE THIS AFTERNOON. AFTER
PERUSING A NUMBER OF SHORT TERM DETERMINISTIC AND HIGH RES
MODELS...ALONG WITH SREF PROBABILITIES...FEEL THAT THE CHANCES OF
SEEING MUCH STORM DEVELOPMENT PRIOR TO 22Z-00Z ARE QUITE LIMITED.
ONE REASON FOR THIS INVOLVES THE FACT THAT THE MAIN SURFACE
TROUGH/COLD FRONT AND RESULTANT LOW LEVEL CONVERGENCE ZONE WILL
STILL REMAIN NORTHWEST OF THE CWA THROUGH THIS TIME. IN
ADDITION...EVEN THE 12Z NAM...WHICH ADVERTISES CONSIDERABLE MLCAPE
VALUES OF AROUND 3000 J/KG ACROSS MUCH OF THE CWA LATER THIS
AFTERNOON...KEEPS AT LEAST A WEAK CAP IN PLACE...WHICH SHOULD BE
TOUGH TO BREAK GIVEN THAT FORCING FROM THE PRIMARY LOW AMPLITUDE
SHORTWAVE OF INTEREST WILL NOT REALLY BE ARRIVING UNTIL THIS
EVENING. AS A RESULT...CUT BACK A BIT ON AFTERNOON POPS...AND
ALTHOUGH THEY WERE NOT HIGH IN THE FIRST PLACE...NOW HAVE ONLY A
TOKEN 20 PERCENT CHANCE LATE THIS AFTERNOON ACROSS ONLY THE
NORTHWEST AND FAR EASTERN COUNTIES...WITH MOST OF THE
CENTRAL/SOUTHWEST FREE OF STORM CHANCES UNTIL AFTER 00Z INCLUDING
THE TRI CITIES. THE EASTERN POPS ARE EVEN QUESTIONABLE...BUT BOTH
THE RUC AND SREF SOMEHOW SUGGEST CONVECTIVE INITIATION IS POSSIBLE
IN THESE AREAS SO KEPT THE SLIGHT CHANCE MENTION. OVERALL...FAVOR
THE 12Z NAM/00Z 4KM WRF-NMM EVOLUTION OF CONVECTIVE CHANCES LATE
THIS AFTERNOON INTO TONIGHT...WITH POTENTIALLY SEVERE STORMS FIRST
FIRING UP TO THE NORTH/WEST OF THE CWA...AND THEN TRYING TO BUILD
SOUTHWARD ALONG THE 850MB FRONT AND INTO A STRENGTHENING LOW LEVEL
JET AXIS THIS EVENING. SEVERE CHANCES ARE STILL THERE...BUT SHOULD
MAINLY FAVOR NEBRASKA ZONES VERSUS NORTHERN KS. MADE NO OTHER
NOTABLE CHANGES AT THIS TIME TO AFTERNOON FORECAST...INCLUDING
HIGH TEMPS.
PREV DISCUSSION... /ISSUED 604 AM CDT TUE MAY 1 2012/
AVIATION...12Z KGRI TAF...LOW LEVEL STRATUS AND BR IS EXPECTED TO
CONTINUE AT KGRI FOR THE NEXT FEW HOURS WITH PREVAILING LIFR CIGS
AND MVFR VSBYS PERSISTING THROUGH ABOUT 01/15Z. AFT
01/15Z...EXPECT A RETURN TO VFR CONDS...WITH INCREASING SOUTHERLY
WINDS...GUSTING TO 20-22KTS THROUGH THE AFTERNOON HOURS. LATE THIS
AFTERNOON...EXPECT AN APPROACHING TROUGH OF LOW PRESSURE TO NEAR
THE TERMINAL...WITH A VCTS OR -TSRA POSSIBLE BETWEEN
02/00Z-02/06Z.
PREV DISCUSSION... /ISSUED 407 AM CDT TUE MAY 1 2012/
SHORT TERM...TODAY THROUGH 12Z FRIDAY. MAIN FORECAST CONCERNS WILL
BE CHANCES FOR THUNDERSTORMS THROUGH MUCH OF THE PERIOD.
SATELLITE AND SURFACE OBSERVATIONS SHOW SOME PATCHY FOG DEVELOPING
EARLY THIS MORNING. VISIBILITIES HAVE DROPPED BELOW A MILE AT A FEW
LOCATIONS...BUT MOSTLY HAVE BEEN ABOVE A MILE. WILL KEEP THE FOG
WITH VISIBILITIES LESS THAN A MILE FOR NOW...BUT WILL WATCH TO SEE
IF WIDESPREAD VISIBILITIES DROP TO A QUARTER MILE.
A SURFACE LOW AND COLD FRONT ON THE HIGH PLAINS WITH A DRY LINE TO
THE SOUTH ALONG THE CENTRAL HIGH PLAINS WILL SLOWLY PUSH TO THE EAST
TODAY. LATE IN THE DAY AN UPPER LEVEL WAVE WILL MOVE ACROSS. CURRENT
DEW POINTS IN THE MID TO UPPER 50S ACROSS THE FORECAST AREA WILL BE
ENOUGH TO ALLOW CAPES THIS AFTERNOON TO RAISE TO OVER 4000 J/KG.
WITH THE FRONT IN THE AREA EXPECT THUNDERSTORMS TO DEVELOP ALONG THE
FRONT LATE THIS AFTERNOON AND CONTINUE INTO THE EVENING HOURS BEFORE
MOVING OFF TO THE EAST. EXPECT THERE MAY BE A LITTLE THAT LINGERS IN
THE EAST LATER TONIGHT.
THE FRONT STALLS ACROSS THE FORECAST AREA LATE TONIGHT INTO
WEDNESDAY NIGHT. ANOTHER UPPER LEVEL WAVE MOVES INTO THE AREA
WEDNESDAY AFTERNOON AND BRINGS ANOTHER CHANCE FOR THUNDERSTORMS TO
THE FORECAST AREA WEDNESDAY AFTERNOON AND NIGHT. THE NAM KEEPS THE
PRECIPITATION FURTHER NORTH THAN THE GFS. BOTH HAVE THE FRONT
FURTHER TO THE SOUTH...BUT THE UPPER WAVE IS FURTHER NORTH. WILL
KEEP CHANCES BEST IN THE NORTH...BUT KEEP SOME CHANCES ACROSS THE
ENTIRE FORECAST AREA. THE UPPER WAVE CONTINUES MOVING THROUGH THE
EASTERN PART OF THE FORECAST AREA THURSDAY SO THERE COULD BE SOME
LINGERING THUNDERSTORMS IN THE EAST ON THURSDAY. FINALLY THURSDAY
NIGHT THE WAVE MOVES TO THE EAST AND EXPECT THAT IT SHOULD BE DRY.
LONG TERM...STARTING 12Z FRIDAY...MODELS IN FAIR AGREEMENT TO START
THE EXTENDED PERIODS WITH LONG WAVE RIDGING ACROSS THE CENTRAL AND
NORTHERN PLAINS...AND A TROUGH OF LOW PRESSURE MOVING ONSHORE ACROSS
THE PACIFIC NORTHWEST. AS A RESULT...EXPECT A DRY END OF THE WORK
WEEK AND START TO THE UPCOMING WEEKEND...WITH ABOVE SEASONAL
TEMPERATURES ACROSS THE ENTIRE AREA.
THIS WARM AND DRY START TO THE EXTENDED WILL BE SHORT LIVED
THOUGH...AS THE AFOREMENTIONED TROUGH TRACKS ACROSS THE INTERMOUNTAIN
WEST AND HELPS TO ERODE THE RIDGE. AT THIS POINT EXTENDED MODELS
BEGIN TO DIVERGE FAIRLY SIGNIFICANTLY...AS THE EC IS MUCH MORE
PROGRESSIVE AND FURTHER NORTH WITH APPROACHING TROUGH...AND GFS
FURTHER AMPLIFIES THE RIDGE...INSTEAD INTENSIFYING A LARGE TROUGH OF
LOW PRESSURE ACROSS THE WESTERN STATES.
WITH SUCH A DISCREPANCY IN LONG TERM MODELS...CONFIDENCE IS NOT
PARTICULARLY HIGH BEYOND SATURDAY...AND STUCK VERY CLOSE TO CONSALL
GUIDANCE FOR POPS IN THE EXTENDED...WITH MODERATE CHANCES FOR SHOWER
AND THUNDERSTORMS BEGINNING SATURDAY EVENING AND PERSISTING THROUGH
MONDAY AFTERNOON...AND SEASONAL TO SLIGHTLY ABOVE SEASONAL
TEMPERATURES PERSISTING. WHILE CONFIDENCE IS NOT EXTREMELY
HIGH...WITH BUILDING INSTABILITY INDICATED BY GFS...AND POTENTIAL OF
PASSING FRONT EVIDENT IN EC...LIKELY WILL SEE SOME SHOWER AND
THUNDERSTORM ACTIVITY EITHER WAY OVER THE LATER HALF OF THE
WEEKEND...SOME OF WHICH WILL HAVE THE POTENTIAL TO BECOME STRONG TO
SEVERE. WITH DIFFERING SOLUTIONS IN MIND...HOWEVER...TIMING IS IN
QUESTION...AND KEPT THIS POTENTIAL SOMEWHAT VAGUE IN HWO FOR THE
TIME BEING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE/AVIATION...HEINLEIN
PREVIOUS UPDATE...PFANNKUCH
SHORT TERM...JCB
LONG TERM...ROSSI
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1225 PM CDT TUE MAY 1 2012
.AVIATION...18Z TAFS FOR KOMA...KLNK AND KOFK. THUNDERSTORM
DEVELOPMENT IS THE PRIMARY CONCERN AT ALL TAF SITES. BELIEVE THAT
A COMPLEX OF STORMS SHOULD DEVELOP ALONG A COLD FRONT NORTHWEST OF
KOFK LATE THIS AFTERNOON...THEN AFFECT THAT SITE FROM ABOUT
00-04Z...THEN ROLL/DEVELOP EAST SOUTHEAST AND AFFECT KLNK/KOMA
FROM ABOUT 04-09Z. UNTIL THEN...VFR CONDITIONS...WITH SOUTH
SOUTHWEST WINDS AT 16 TO 18 SUSTAINED...WITH GUSTS UP TO 26 TO
28KTS. AFTER THE STORMS MOVE THROUGH...SOME MVFR FOG OR HAZE COULD
DEVELOP FROM ABOUT 09Z-15Z. COULD ALSO SOME SEE SOME LOWER MVFR
STRATO CLOUDS DEVELOPING OVERNIGHT AS WELL.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 956 AM CDT TUE MAY 1 2012/
DISCUSSION...
IN THE MORNING UPDATE OF THE FORECAST, ADDED IN A SMALL CHANCE OF
THUNDERSTORMS ACROSS EXTREME SOUTHEAST NEBRASKA AND SOUTHWEST
IOWA. WEAK WAVE MOVING THROUGH THE REGION...IN CONJUNCTION WITH A
VERY SUBTLE SURFACE TROUGH WAS TRIGGERING SOME CONVECTION IN
NORTHEAST KANSAS. LATEST VISIBLE SATELLITE IMAGERY INDICATES AN
ACCAS FIELD MOVING THROUGH SOUTHEAST NEBRASKA WITH SOME VERTICAL
DEVELOPMENT BETWEEN FALLS CITY AND AND BEATRICE. LATEST HRRR MODEL
SUGGESTS THAT THIS COULD DEVELOP YET THIS MORNING...AND REGIONAL
88DS HAVE SHOWN SOME MID LEVEL DEVELOPMENT JUST SOUTH OF FALLS CITY.
OTHERWISE...REMAINDER OF THE FORECAST SEEMS ON TRACK...WITH
CONVECTIVE DEVELOPMENT POSSIBLE LATER THIS AFTERNOON ACROSS
EXTREME NORTHEAST NEBRASKA ALONG AN ADVANCING COLD FRONT. 12Z NAM
AND 06Z GFS AND 09Z SREF ALSO SUGGEST THAT ISOLATED ACTIVITY
COULD DEVELOP IN THE WARM AIR ADVECTION ZONE AHEAD OF THE COLD
FRONT. HAVE NOT BOUGHT INTO THAT YET...BUT WILL DO FURTHER
ANALYSIS.
DEWALD
PREV DISCUSSION... /ISSUED 333 AM CDT TUE MAY 1 2012/
DISCUSSION...
MAIN FORECAST CONCERN IS CONVECTIVE POTENTIAL TODAY AND TOMORROW.
SUBJECTIVE 00Z UPPER AIR ANALYSIS INDICATES BROADLY ZONAL FLOW
ACROSS THE CONUS...WITH A TROUGH DIGGING INTO THE PACIFIC
NORTHWEST. STRONGEST UPPER-LEVEL JET WAS FOCUSED JUST
OFFSHORE...WITH 110KT JET STREAK JUST OFF THE OR COAST. SEVERAL
WEAK SHORTWAVES WERE RIPPLING THROUGH THE FLOW...INCLUDING ONE IN
AZ...ANOTHER IN SW TX...AND ANOTHER IN WY/CO. AHEAD OF AN 850MB
TROUGH DEVELOPING IN THE LEE OF THE ROCKIES...MOISTURE WAS FLOWING
OFF THE GULF...WITH 8C+ DEWPOINTS NOSING INTO NORTHERN KS/CENTRAL
MO...AND 12C+ DEWPOINTS CLOSE BEHIND. STRONG MID-LEVEL LAPSE RATES
WERE NOTED ACROSS THE ROCKIES INTO THE HIGH PLAINS...WITH 700-500MB
TEMPERATURE DIFFERENCES OF 20-24C PEAKING IN CO/NM. SURFACE LOW
ALSO WAS DEVELOPING IN THE LEE OF THE ROCKIES...WITH LOW CENTERED IN
WESTERN SD AND SECONDARY LOW IN SOUTHWEST CO.
FOCUS IS ON CONVECTIVE POTENTIAL THIS EVENING/TONIGHT...THEN AGAIN
TOMORROW LATE AFTERNOON/EVENING/OVERNIGHT. WARMING MID-LEVEL
TEMPERATURES WILL CREATE A CAP TODAY...AND ALL MODELS EXCEPT THE NAM
AND SOME SREF MEMBERS KEEP THE CWA CAPPED THROUGH 00Z. HAVING
TROUBLE FINDING A REASON TO FOLLOW THE NAM...WITH MODELS INDICATING
RISING MID-LEVEL TEMPS...AND HAVE FOLLOWED CLOSER TO GFS/ECMWF
SOLUTION. IF ANY SURFACE-BASED STORMS DID DEVELOP IN THE
AFTERNOON...LOW-LEVEL FLOW AND 0-1KM SHEAR LOOK RATHER WEAK...BUT
DEEP-LAYER SHEAR IS STRONG ENOUGH TO SUPPORT SUPERCELLS.
THUS...THINK ANY STRAY AFTERNOON STORMS WOULD CARRY MAINLY A HAIL
AND WIND THREAT. WITH THE MORE LIKELY SCENARIO OF EVENING
THUNDERSTORMS MOVING INTO THE CWA...AND LIKELY ELEVATED...THINK THE
MAIN RISK WOULD BE HAIL. THUNDERSTORMS ARE LIKELY TO DEVELOP AND
MOVE ACROSS THE AREA OVERNIGHT...BUT DO THINK THEY SHOULD CLEAR
THROUGH BY DAYBREAK.
ON WEDNESDAY...FRONTAL BOUNDARY IS PROGGED TO STALL AND LINGER
ACROSS CENTRAL TO NORTHEAST NEB...PROVIDING A FOCUS FOR THUNDERSTORM
DEVELOPMENT ON WEDNESDAY. CAP REMAINS A CONCERN...BUT GFS/ECMWF
ARE A LITTLE MORE INCLINED TO ERODE THE CAP IN THE LATE
AFTERNOON...WITH CONVECTION BREAKING OUT ALONG THE BOUNDARY BETWEEN
21-00Z. AGAIN...LOW-LEVEL WINDS REMAIN ON THE WEAK SIDE...BUT
PRESENCE OF A BOUNDARY COULD PROVIDE A SOURCE OF LOW-LEVEL
VORTICITY...INDICATING MORE OF A TORNADO POTENTIAL ON WEDNESDAY...AS
WELL AS HAIL AND WIND THREATS AS DEEP-LAYER SHEAR REMAINS ADEQUATE
TO SUPPORT SUPERCELLS. DO THINK THAT CONVECTION WILL DEVELOP INTO A
COMPLEX AHEAD OF THE FRONT THROUGH THE NIGHT...WITH FRONT FOLLOWING
LATE WEDNESDAY NIGHT/THURSDAY MORNING. HAVE TRIED TO PUSH
CONVECTION OUT A LITTLE FASTER ON THURSDAY...THOUGH ONCE
AGAIN...FRONT HANGS UP IN OR NEAR THE CWA. STORMS MAY DEVELOP AGAIN
ALONG THAT FRONT AND MOVE INTO THE SOUTHERN CWA ON FRIDAY.
FRIDAY AND BEYOND...FORECAST BECOMES MUDDY. KEPT FRIDAY THROUGH
SATURDAY MAINLY DRY AS MID TO UPPER-LEVEL RIDGING BUILDS OVER THE
CENTRAL PLAINS...WITH THE EXCEPTION OF A SMALL AREA OF CHANCE POPS
IN THE NORTHERN CWA ON FRIDAY NIGHT AS RAIN IN SD/MN APPROACHES THE
BORDER AREA. TEMPERATURES WILL WARM THROUGH THE PERIOD WITH THE
RISING 500MB HEIGHTS...AND WITH PERSISTENT LOW-LEVEL
MOISTURE...SHOULD FEEL QUITE MUGGY. THOUGH MODEL BLENDS AND
COORDINATION WITH NEIGHBORS KEEPS PRECIP IN THE FORECAST SATURDAY
NIGHT THROUGH TUESDAY...BELIEVE THAT THIS IS NOT REPRESENTATIVE OF
HOW THE PATTERN WILL EVOLVE. STRONG UPPER-LEVEL RIDGE WILL SHIFT
EAST OF THE CWA AS UPPER LOW DEEPENS IN THE SOUTHWESTERN US...AND AS
THE LOW STRENGTHENS...SEVERAL SHORTWAVES MAY EJECT AHEAD OF
IT...BRINGING TRANSIENT CHANCES FOR SHOWERS AND THUNDERSTORMS
ACROSS THE CENTRAL PLAINS. MODELS HAVE LITTLE AGREEMENT ON THE
TIMING OF THESE WAVES...AND THUS THE BLENDS CREATE A FORECAST LOADED
WITH PRECIPITATION CHANCES WHEN ONLY A COUPLE OF PERIODS WILL LIKELY
SEE RAIN. BEST CHANCE FOR WIDESPREAD AND PERSISTENT RAIN WOULD BE
WHEN THE UPPER LOW EVENTUALLY EJECTS ACROSS THE CENTRAL PLAINS...BUT
FOR NOW...THIS IS OUTSIDE THE FORECAST PERIOD.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1036 AM CDT TUE MAY 1 2012
.UPDATE...JUST COMPLETED THE FIRST UPDATE OF THE DAY...ADDRESSING
TWO MAIN TOPICS. FIRST OFF...PULLED ALL MENTION OF FOG...AS
VISIBILITIES HAVE GREATLY IMPROVED...AND MOSTLY CLEAR SKIES NOW
DOMINATE MOST OF THE CWA...EXCEPT FOR STUBBORN LOW STRATUS
HANGING FIRM MAINLY WEST OF AN ORD-BEAVER CITY LINE WHICH SHOULD
ALSO SCATTER OUT EVENTUALLY. SECOND AND OVERALL MORE IMPORTANT
FOCUS WAS THUNDERSTORM CHANCES THROUGH LATE THIS AFTERNOON. AFTER
PERUSING A NUMBER OF SHORT TERM DETERMINISTIC AND HIGH RES
MODELS...ALONG WITH SREF PROBABILITIES...FEEL THAT THE CHANCES OF
SEEING MUCH STORM DEVELOPMENT PRIOR TO 22Z-00Z ARE QUITE LIMITED.
ONE REASON FOR THIS INVOLVES THE FACT THAT THE MAIN SURFACE
TROUGH/COLD FRONT AND RESULTANT LOW LEVEL CONVERGENCE ZONE WILL
STILL REMAIN NORTHWEST OF THE CWA THROUGH THIS TIME. IN
ADDITION...EVEN THE 12Z NAM...WHICH ADVERTISES CONSIDERABLE MLCAPE
VALUES OF AROUND 3000 J/KG ACROSS MUCH OF THE CWA LATER THIS
AFTERNOON...KEEPS AT LEAST A WEAK CAP IN PLACE...WHICH SHOULD BE
TOUGH TO BREAK GIVEN THAT FORCING FROM THE PRIMARY LOW AMPLITUDE
SHORTWAVE OF INTEREST WILL NOT REALLY BE ARRIVING UNTIL THIS
EVENING. AS A RESULT...CUT BACK A BIT ON AFTERNOON POPS...AND
ALTHOUGH THEY WERE NOT HIGH IN THE FIRST PLACE...NOW HAVE ONLY A
TOKEN 20 PERCENT CHANCE LATE THIS AFTERNOON ACROSS ONLY THE
NORTHWEST AND FAR EASTERN COUNTIES...WITH MOST OF THE
CENTRAL/SOUTHWEST FREE OF STORM CHANCES UNTIL AFTER 00Z INCLUDING
THE TRI CITIES. THE EASTERN POPS ARE EVEN QUESTIONABLE...BUT BOTH
THE RUC AND SREF SOMEHOW SUGGEST CONVECTIVE INITIATION IS POSSIBLE
IN THESE AREAS SO KEPT THE SLIGHT CHANCE MENTION. OVERALL...FAVOR
THE 12Z NAM/00Z 4KM WRF-NMM EVOLUTION OF CONVECTIVE CHANCES LATE
THIS AFTERNOON INTO TONIGHT...WITH POTENTIALLY SEVERE STORMS FIRST
FIRING UP TO THE NORTH/WEST OF THE CWA...AND THEN TRYING TO BUILD
SOUTHWARD ALONG THE 850MB FRONT AND INTO A STRENGTHENING LOW LEVEL
JET AXIS THIS EVENING. SEVERE CHANCES ARE STILL THERE...BUT SHOULD
MAINLY FAVOR NEBRASKA ZONES VERSUS NORTHERN KS. MADE NO OTHER
NOTABLE CHANGES AT THIS TIME TO AFTERNOON FORECAST...INCLUDING
HIGH TEMPS.
&&
.PREV DISCUSSION... /ISSUED 604 AM CDT TUE MAY 1 2012/
AVIATION...12Z KGRI TAF...LOW LEVEL STRATUS AND BR IS EXPECTED TO
CONTINUE AT KGRI FOR THE NEXT FEW HOURS WITH PREVAILING LIFR CIGS
AND MVFR VSBYS PERSISTING THROUGH ABOUT 01/15Z. AFT
01/15Z...EXPECT A RETURN TO VFR CONDS...WITH INCREASING SOUTHERLY
WINDS...GUSTING TO 20-22KTS THROUGH THE AFTERNOON HOURS. LATE THIS
AFTERNOON...EXPECT AN APPROACHING TROUGH OF LOW PRESSURE TO NEAR
THE TERMINAL...WITH A VCTS OR -TSRA POSSIBLE BETWEEN
02/00Z-02/06Z.
PREV DISCUSSION... /ISSUED 407 AM CDT TUE MAY 1 2012/
SHORT TERM...TODAY THROUGH 12Z FRIDAY. MAIN FORECAST CONCERNS WILL
BE CHANCES FOR THUNDERSTORMS THROUGH MUCH OF THE PERIOD.
SATELLITE AND SURFACE OBSERVATIONS SHOW SOME PATCHY FOG DEVELOPING
EARLY THIS MORNING. VISIBILITIES HAVE DROPPED BELOW A MILE AT A FEW
LOCATIONS...BUT MOSTLY HAVE BEEN ABOVE A MILE. WILL KEEP THE FOG
WITH VISIBILITIES LESS THAN A MILE FOR NOW...BUT WILL WATCH TO SEE
IF WIDESPREAD VISIBILITIES DROP TO A QUARTER MILE.
A SURFACE LOW AND COLD FRONT ON THE HIGH PLAINS WITH A DRY LINE TO
THE SOUTH ALONG THE CENTRAL HIGH PLAINS WILL SLOWLY PUSH TO THE EAST
TODAY. LATE IN THE DAY AN UPPER LEVEL WAVE WILL MOVE ACROSS. CURRENT
DEW POINTS IN THE MID TO UPPER 50S ACROSS THE FORECAST AREA WILL BE
ENOUGH TO ALLOW CAPES THIS AFTERNOON TO RAISE TO OVER 4000 J/KG.
WITH THE FRONT IN THE AREA EXPECT THUNDERSTORMS TO DEVELOP ALONG THE
FRONT LATE THIS AFTERNOON AND CONTINUE INTO THE EVENING HOURS BEFORE
MOVING OFF TO THE EAST. EXPECT THERE MAY BE A LITTLE THAT LINGERS IN
THE EAST LATER TONIGHT.
THE FRONT STALLS ACROSS THE FORECAST AREA LATE TONIGHT INTO
WEDNESDAY NIGHT. ANOTHER UPPER LEVEL WAVE MOVES INTO THE AREA
WEDNESDAY AFTERNOON AND BRINGS ANOTHER CHANCE FOR THUNDERSTORMS TO
THE FORECAST AREA WEDNESDAY AFTERNOON AND NIGHT. THE NAM KEEPS THE
PRECIPITATION FURTHER NORTH THAN THE GFS. BOTH HAVE THE FRONT
FURTHER TO THE SOUTH...BUT THE UPPER WAVE IS FURTHER NORTH. WILL
KEEP CHANCES BEST IN THE NORTH...BUT KEEP SOME CHANCES ACROSS THE
ENTIRE FORECAST AREA. THE UPPER WAVE CONTINUES MOVING THROUGH THE
EASTERN PART OF THE FORECAST AREA THURSDAY SO THERE COULD BE SOME
LINGERING THUNDERSTORMS IN THE EAST ON THURSDAY. FINALLY THURSDAY
NIGHT THE WAVE MOVES TO THE EAST AND EXPECT THAT IT SHOULD BE DRY.
LONG TERM...STARTING 12Z FRIDAY...MODELS IN FAIR AGREEMENT TO START
THE EXTENDED PERIODS WITH LONG WAVE RIDGING ACROSS THE CENTRAL AND
NORTHERN PLAINS...AND A TROUGH OF LOW PRESSURE MOVING ONSHORE ACROSS
THE PACIFIC NORTHWEST. AS A RESULT...EXPECT A DRY END OF THE WORK
WEEK AND START TO THE UPCOMING WEEKEND...WITH ABOVE SEASONAL
TEMPERATURES ACROSS THE ENTIRE AREA.
THIS WARM AND DRY START TO THE EXTENDED WILL BE SHORT LIVED
THOUGH...AS THE AFOREMENTIONED TROUGH TRACKS ACROSS THE INTERMOUNTAIN
WEST AND HELPS TO ERODE THE RIDGE. AT THIS POINT EXTENDED MODELS
BEGIN TO DIVERGE FAIRLY SIGNIFICANTLY...AS THE EC IS MUCH MORE
PROGRESSIVE AND FURTHER NORTH WITH APPROACHING TROUGH...AND GFS
FURTHER AMPLIFIES THE RIDGE...INSTEAD INTENSIFYING A LARGE TROUGH OF
LOW PRESSURE ACROSS THE WESTERN STATES.
WITH SUCH A DISCREPANCY IN LONG TERM MODELS...CONFIDENCE IS NOT
PARTICULARLY HIGH BEYOND SATURDAY...AND STUCK VERY CLOSE TO CONSALL
GUIDANCE FOR POPS IN THE EXTENDED...WITH MODERATE CHANCES FOR SHOWER
AND THUNDERSTORMS BEGINNING SATURDAY EVENING AND PERSISTING THROUGH
MONDAY AFTERNOON...AND SEASONAL TO SLIGHTLY ABOVE SEASONAL
TEMPERATURES PERSISTING. WHILE CONFIDENCE IS NOT EXTREMELY
HIGH...WITH BUILDING INSTABILITY INDICATED BY GFS...AND POTENTIAL OF
PASSING FRONT EVIDENT IN EC...LIKELY WILL SEE SOME SHOWER AND
THUNDERSTORM ACTIVITY EITHER WAY OVER THE LATER HALF OF THE
WEEKEND...SOME OF WHICH WILL HAVE THE POTENTIAL TO BECOME STRONG TO
SEVERE. WITH DIFFERING SOLUTIONS IN MIND...HOWEVER...TIMING IS IN
QUESTION...AND KEPT THIS POTENTIAL SOMEWHAT VAGUE IN HWO FOR THE
TIME BEING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...PFANNKUCH
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
956 AM CDT TUE MAY 1 2012
.DISCUSSION...
IN THE MORNING UPDATE OF THE FORECAST, ADDED IN A SMALL CHANCE OF
THUNDERSTORMS ACROSS EXTREME SOUTHEAST NEBRASKA AND SOUTHWEST
IOWA. WEAK WAVE MOVING THROUGH THE REGION...IN CONJUNCTION WITH A
VERY SUBTLE SURFACE TROUGH WAS TRIGGERING SOME CONVECTION IN
NORTHEAST KANSAS. LATEST VISIBLE SATELLITE IMAGERY INDICATES AN
ACCAS FIELD MOVING THROUGH SOUTHEAST NEBRASKA WITH SOME VERTICAL
DEVELOPMENT BETWEEN FALLS CITY AND AND BEATRICE. LATEST HRRR MODEL
SUGGESTS THAT THIS COULD DEVELOP YET THIS MORNING...AND REGIONAL
88DS HAVE SHOWN SOME MID LEVEL DEVELOPMENT JUST SOUTH OF FALLS CITY.
OTHERWISE...REMAINDER OF THE FORECAST SEEMS ON TRACK...WITH
CONVECTIVE DEVELOPMENT POSSIBLE LATER THIS AFTERNOON ACROSS
EXTREME NORTHEAST NEBRASKA ALONG AN ADVANCING COLD FRONT. 12Z NAM
AND 06Z GFS AND 09Z SREF ALSO SUGGEST THAT ISOLATED ACTIVITY
COULD DEVELOP IN THE WARM AIR ADVECTION ZONE AHEAD OF THE COLD
FRONT. HAVE NOT BOUGHT INTO THAT YET...BUT WILL DO FURTHER
ANALYSIS.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 605 AM CDT TUE MAY 1 2012/
AVIATION...
12Z TAFS FOR KOMA...KLNK...KOFK.
MAIN AVIATION CONCERNS ARE TIMING OF LOW CLOUDS BREAKING UP THIS
MORNING THEN THUNDERSTORM CHANCES FOR THE AFTERNOON AND EVENING.
MOIST SOUTHERLY LOW LEVEL FLOW IS IN PLACE AHEAD OF A COLD THAT
SHOULD MOVE TOWARD THE AREA LATER TODAY. LOW CLOUDS ARE EXPECTED TO
BREAK UP THIS MORNING LEAVING VFR CONDITIONS BY LATE MORNING OR
EARLY AFTERNOON. AS THE ATMOSPHERE DESTABILIZES THIS AFTERNOON...
THUNDERSTORM CHANCES INCREASE MOSTLY AFTER 21Z. THE CHANCE WILL
CONTINUE INTO THE EVENING AND POSSIBLY OVERNIGHT. LOW CLOUDS SEEM
POSSIBLE AGAIN AFTER MIDNIGHT.
MILLER
PREV DISCUSSION... /ISSUED 333 AM CDT TUE MAY 1 2012/
DISCUSSION...
MAIN FORECAST CONCERN IS CONVECTIVE POTENTIAL TODAY AND TOMORROW.
SUBJECTIVE 00Z UPPER AIR ANALYSIS INDICATES BROADLY ZONAL FLOW
ACROSS THE CONUS...WITH A TROUGH DIGGING INTO THE PACIFIC
NORTHWEST. STRONGEST UPPER-LEVEL JET WAS FOCUSED JUST
OFFSHORE...WITH 110KT JET STREAK JUST OFF THE OR COAST. SEVERAL
WEAK SHORTWAVES WERE RIPPLING THROUGH THE FLOW...INCLUDING ONE IN
AZ...ANOTHER IN SW TX...AND ANOTHER IN WY/CO. AHEAD OF AN 850MB
TROUGH DEVELOPING IN THE LEE OF THE ROCKIES...MOISTURE WAS FLOWING
OFF THE GULF...WITH 8C+ DEWPOINTS NOSING INTO NORTHERN KS/CENTRAL
MO...AND 12C+ DEWPOINTS CLOSE BEHIND. STRONG MID-LEVEL LAPSE RATES
WERE NOTED ACROSS THE ROCKIES INTO THE HIGH PLAINS...WITH 700-500MB
TEMPERATURE DIFFERENCES OF 20-24C PEAKING IN CO/NM. SURFACE LOW
ALSO WAS DEVELOPING IN THE LEE OF THE ROCKIES...WITH LOW CENTERED IN
WESTERN SD AND SECONDARY LOW IN SOUTHWEST CO.
FOCUS IS ON CONVECTIVE POTENTIAL THIS EVENING/TONIGHT...THEN AGAIN
TOMORROW LATE AFTERNOON/EVENING/OVERNIGHT. WARMING MID-LEVEL
TEMPERATURES WILL CREATE A CAP TODAY...AND ALL MODELS EXCEPT THE NAM
AND SOME SREF MEMBERS KEEP THE CWA CAPPED THROUGH 00Z. HAVING
TROUBLE FINDING A REASON TO FOLLOW THE NAM...WITH MODELS INDICATING
RISING MID-LEVEL TEMPS...AND HAVE FOLLOWED CLOSER TO GFS/ECMWF
SOLUTION. IF ANY SURFACE-BASED STORMS DID DEVELOP IN THE
AFTERNOON...LOW-LEVEL FLOW AND 0-1KM SHEAR LOOK RATHER WEAK...BUT
DEEP-LAYER SHEAR IS STRONG ENOUGH TO SUPPORT SUPERCELLS.
THUS...THINK ANY STRAY AFTERNOON STORMS WOULD CARRY MAINLY A HAIL
AND WIND THREAT. WITH THE MORE LIKELY SCENARIO OF EVENING
THUNDERSTORMS MOVING INTO THE CWA...AND LIKELY ELEVATED...THINK THE
MAIN RISK WOULD BE HAIL. THUNDERSTORMS ARE LIKELY TO DEVELOP AND
MOVE ACROSS THE AREA OVERNIGHT...BUT DO THINK THEY SHOULD CLEAR
THROUGH BY DAYBREAK.
ON WEDNESDAY...FRONTAL BOUNDARY IS PROGGED TO STALL AND LINGER
ACROSS CENTRAL TO NORTHEAST NEB...PROVIDING A FOCUS FOR THUNDERSTORM
DEVELOPMENT ON WEDNESDAY. CAP REMAINS A CONCERN...BUT GFS/ECMWF
ARE A LITTLE MORE INCLINED TO ERODE THE CAP IN THE LATE
AFTERNOON...WITH CONVECTION BREAKING OUT ALONG THE BOUNDARY BETWEEN
21-00Z. AGAIN...LOW-LEVEL WINDS REMAIN ON THE WEAK SIDE...BUT
PRESENCE OF A BOUNDARY COULD PROVIDE A SOURCE OF LOW-LEVEL
VORTICITY...INDICATING MORE OF A TORNADO POTENTIAL ON WEDNESDAY...AS
WELL AS HAIL AND WIND THREATS AS DEEP-LAYER SHEAR REMAINS ADEQUATE
TO SUPPORT SUPERCELLS. DO THINK THAT CONVECTION WILL DEVELOP INTO A
COMPLEX AHEAD OF THE FRONT THROUGH THE NIGHT...WITH FRONT FOLLOWING
LATE WEDNESDAY NIGHT/THURSDAY MORNING. HAVE TRIED TO PUSH
CONVECTION OUT A LITTLE FASTER ON THURSDAY...THOUGH ONCE
AGAIN...FRONT HANGS UP IN OR NEAR THE CWA. STORMS MAY DEVELOP AGAIN
ALONG THAT FRONT AND MOVE INTO THE SOUTHERN CWA ON FRIDAY.
FRIDAY AND BEYOND...FORECAST BECOMES MUDDY. KEPT FRIDAY THROUGH
SATURDAY MAINLY DRY AS MID TO UPPER-LEVEL RIDGING BUILDS OVER THE
CENTRAL PLAINS...WITH THE EXCEPTION OF A SMALL AREA OF CHANCE POPS
IN THE NORTHERN CWA ON FRIDAY NIGHT AS RAIN IN SD/MN APPROACHES THE
BORDER AREA. TEMPERATURES WILL WARM THROUGH THE PERIOD WITH THE
RISING 500MB HEIGHTS...AND WITH PERSISTENT LOW-LEVEL
MOISTURE...SHOULD FEEL QUITE MUGGY. THOUGH MODEL BLENDS AND
COORDINATION WITH NEIGHBORS KEEPS PRECIP IN THE FORECAST SATURDAY
NIGHT THROUGH TUESDAY...BELIEVE THAT THIS IS NOT REPRESENTATIVE OF
HOW THE PATTERN WILL EVOLVE. STRONG UPPER-LEVEL RIDGE WILL SHIFT
EAST OF THE CWA AS UPPER LOW DEEPENS IN THE SOUTHWESTERN US...AND AS
THE LOW STRENGTHENS...SEVERAL SHORTWAVES MAY EJECT AHEAD OF
IT...BRINGING TRANSIENT CHANCES FOR SHOWERS AND THUNDERSTORMS
ACROSS THE CENTRAL PLAINS. MODELS HAVE LITTLE AGREEMENT ON THE
TIMING OF THESE WAVES...AND THUS THE BLENDS CREATE A FORECAST LOADED
WITH PRECIPITATION CHANCES WHEN ONLY A COUPLE OF PERIODS WILL LIKELY
SEE RAIN. BEST CHANCE FOR WIDESPREAD AND PERSISTENT RAIN WOULD BE
WHEN THE UPPER LOW EVENTUALLY EJECTS ACROSS THE CENTRAL PLAINS...BUT
FOR NOW...THIS IS OUTSIDE THE FORECAST PERIOD.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
145 AM EDT TUE MAY 1 2012
.SYNOPSIS...
A WARM FRONT WILL LIFT ACROSS NEW YORK FROM THE OHIO VALLEY THIS EVENING
WITH SOME SHOWERS AND AN ISOLATED THUNDERSTORM OR TWO. A COLD
FRONT WILL CROSS THE REGION LATE TONIGHT WITH ANOTHER ROUND OF
SHOWERS. CONDITIONS WILL THEN BECOME NOTABLY WARMER BUT UNSETTLED
ACROSS THE REGION TUESDAY THROUGH THE REMAINDER OF THE WEEK AS
TEMPERATURES WILL CLIMB WELL ABOVE NORMAL.
&&
.NEAR TERM /THROUGH TODAY/...
A BROAD AREA OF LOW PRESSURE WILL LIFT TO THE NORTHEAST ACROSS
WESTERN NEW YORK OVERNIGHT. SHOWERS HAVE SPREAD INTO WESTERN NEW
YORK LATE THIS EVENING...WITH THESE SHOWERS FORECAST TO CONTINUE
TO MOVE ACROSS THE REGION OVERNIGHT. THE HRRR IN PARTICULAR HAS BEEN
QUITE CONSISTENT IN BRINGING SHOWERS ACROSS WESTERN NEW YORK
TONIGHT THROUGH 10Z...WITH RUNS OF THE NAM/RGEM ALSO SIMILAR BUT
PERHAPS A TAD SLOW. RADAR TRENDS ARE IN GENERAL SUPPORT OF THIS
CONSENSUS...AND ARE WELL CAPTURED BY ALL OF THESE MODELS...THE
HRRR IN PARTICULAR. ALSO...EXPECT SOME LIGHTNING WILL REACH
WESTERN NEW YORK WITH THIS AS WELL...THOUGH SURFACE BASED
CONVECTION SHOULD REMAIN TO THE SOUTH...WITH ELEVATED CONVECTION
ACROSS WESTERN NEW YORK SUPPORTING A MINIMAL (TO NIL) SEVERE
WEATHER THREAT. THIS SAID...EXPECT SHOWERS TO BRING A HALF INCH OR
SO OF RAIN TO SOUTHERN PORTIONS OF THE CWA...WITH LOCALLY HIGHER
AMOUNTS POSSIBLE IN THUNDERSTORMS. THE BEST CHANCE FOR
THUNDERSTORMS AND HIGHER QPF IN THE INCH RANGE APPEAR TO BE ACROSS
WESTERN PORTIONS OF THE SOUTHERN TIER...FOLLOWING BOTH HRRR
FORECASTS AND RADAR TRENDS.
OTHERWISE...TEMPERATURES WILL REMAIN MILD WITH WARMER AIR
SHIFTING ACROSS THE REGION WITHIN THE LOW PRESSURE SYSTEMS WARM
SECTOR. TEMPS WILL NOT FALL MUCH OVERNIGHT AND MAY IN FACT REMAIN
STEADY OR RISE. SOUTH I-90 WHERE WINDS HAVE GONE TO THE SE BEHIND
THE WARM FRONT...HEDGE ON THE WARM SIDE OF MOS GUIDANCE...WITH
STEADY TEMPERATURES IN THE 50S LIKELY OVERNIGHT.
TUESDAY...FRONT MAY STILL BE PRESSING EAST ACROSS CENTRAL AND
NORTHERN NEW YORK TUESDAY MORNING WITH CHANCES FOR SHOWERS. ALL
AREAS SHOULD BE DRY BY THE AFTERNOON WITH A WEAK HIGH PRESSURE
BUILDING IN BEHIND THE FRONT. MOST AREAS WILL TURN OUT PARTLY TO
MOSTLY SUNNY BY AFTERNOON. HIGHS LOOK TO REACH INTO THE LOW 60S
ESPECIALLY ACROSS WESTERN NEW YORK WHERE THE SUN WILL BREAK OUT
EARLIER THAN CENTRAL AND NORTHERN NY.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
WE WILL SEE A QUIET START TO THE PERIOD AS WESTERN AND CENTRAL NEW
YORK WILL BE FALLING UNDER THE INFLUENCE OF A BROAD UPPER LEVEL
RIDGE UPSTREAM. SUBSIDENCE OVER THE REGION SHOULD ALLOW FOR MOSTLY
CLEAR SKIES. THIS COMBINED WITH LIGHT WINDS SHOULD ALLOW FOR
TEMPERATURES TO DROP INTO THE UPPER 40S WITH MID 40S IN THE USUAL
COOL SPOTS OF THE SOUTHERN/TIER AND NORTH COUNTRY.
WEDNESDAY WILL FEATURE THE BEGINNING OF THE PRONOUNCED WARM-UP THAT
WILL BE AFFECTING THE REGION THROUGH THE REST OF THE WEEK. THE BROAD
UPPER LEVEL RIDGE WILL SETTLE OVER THE EASTERN UNITED STATES WHILE
RETURN FLOW AROUND A STRONG SURFACE HIGH ANCHORED OFF THE SOUTHEAST
U.S. COAST WILL PUMP INCREASINGLY WARM AND MOIST AIR NORTHWARDS
ACROSS THE OHIO VALLEY AND INTO THE GREAT LAKES REGION. THIS WILL
RESULT IN TEMPERATURES THAT WILL RISE WELL INTO THE 70S WEDNESDAY
AND THURSDAY WITH SOME AREAS POSSIBLY BREACHING 80 ON THURSDAY. IN
ADDITION TO THE WARMTH...IT WILL START TO FEEL MUGGY AS WELL AS
SURFACE DEW POINTS WILL ALSO RISE INTO 50S WEDNESDAY AND POSSIBLY LOW
60S THURSDAY AS THE RICH GULF MOISTURE SURGES NORTHWARDS.
WITH THE WARM AND MOIST AIR ADVECTING NORTH INTO THE REGION...WE
INTRODUCE THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS. THE GREATEST
POTENTIAL FOR CONVECTION ON WEDNESDAY WILL BE FOUND ACROSS
FAR WESTERN NEW YORK DURING LATE AFTERNOON AS THE LEADING EDGE OF A
THETA-E RIDGE SLIDES INTO THE NIAGARA FRONTIER. THE THREAT FOR
CONVECTION CONTINUES INTO WEDNESDAY NIGHT AS MODELS INDICATE ML CAPE
VALUES OF AROUND 400 J/KG WEST OF THE GENESEE VALLEY.
CONDITIONS THURSDAY SHOULD BE RIPE FOR SHOWERS AND THUNDERSTORMS AS
WE WILL REMAIN IN A VERY MOIST AIRMASS...HOWEVER WITH LIGHT FLOW AND
A LACK OF A CLEAR TRIGGER SUCH AS A SHORTWAVE...AM NOT EXPECTING
ORGANIZED OR SEVERE CONVECTION. HOWEVER MAY SEE WIDESPREAD
LAKE-BREEZE INDUCED SHOWERS/THUNDERSTORMS...PARTICULARLY INT HE
AFTERNOON/EVENING HOURS. THE FLY IN THE OINTMENT MAY BE WEAK
MID-LEVEL LAPSE RATES THAT MAY PUT A LID ON CONVECTION FROM BREAKING
OUT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
EXPECT MUCH OF THE SAME ON FRIDAY AS THE VERY WARM/MOIST AND
UNSTABLE AIRMASS LINGERS OVER THE REGION WITH HIGHS IN THE 70S AND
AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS. THE FORECAST BECOMES
MURKIER BY THE WEEKEND WITH THE MODELS AT ODDS OVER THE
LOCATION/TIMING OF A COLD FRONT SWEEPING SOUTH OUT OF CANADA. THE
GFS PUSHES THE FRONT ACROSS THE FORECAST AREA SATURDAY...A PROSPECT
THAT WOULD RESULT IN A MUCH COOLER/DRIER WEEKEND THAN CURRENTLY
FORECAST. THE ECMWF...ON THE OTHER HAND...PUSHES A MUCH WEAKER
FRONT ACROSS THE REGION LATE ON SUNDAY. GIVEN THESE
DIFFERENCES...WILL OPT FOR A FORECAST THAT LEANS MORE TOWARDS THE
ECMWF/PERSISTENCE WITH HIGHS IN THE LOW 70S...LOWS IN THE 50S...AND
CHANCE POPS.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A NEARLY SOLID BAND OF RAIN WILL WORK ITS WAY ACROSS THE REGION
DURING THE OVERNIGHT HOURS...EXITING THE EASTERN EDGE OF THE
FORECAST AREA AFTER 08Z-10Z. WILL SEE A DROP IN CEILINGS ALONG THE
TRAILING EDGE OF THE PRECIP SHIELD WITH VFR/MVFR CIGS FALLING TO IFR
AVERAGING 800FT. THIS TRAILING CLOUD WILL LIFT SOMEWHAT THROUGH THE
DAY WITH MVFR CIGS MID-LATE MORNING...THEN BREAKS IN THE CLOUDINESS
LATE IN THE DAY LEADING TO CLEARING.
OUTLOOK...
TUESDAY NIGHT...VFR.
WEDNESDAY THROUGH SATURDAY...VFR/MVFR IN SHOWERS.
&&
.MARINE...
WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
DURING THIS PERIOD...ALTHOUGH MORE ACTIVE WEATHER CAN BE EXPECTED.
A WARM FRONT IS LIFTING ACROSS THE LOWER GREAT LAKES FROM THE OHIO VALLEY
TODAY. THIS WILL PRODUCE GENTLE TO OCCASIONALLY MODERATE EASTERLIES
ON LAKES ERIE AND ONTARIO...THEN AS THE WARM FRONT AND ITS SHOWERS
MOVE THROUGH THIS AFTERNOON AND EVENING WINDS WILL BECOME MORE
SOUTHEASTERLY. OVERNIGHT A SURFACE LOW WILL SHIFT EAST ACROSS LAKE ONTARIO
WITH WINDS SHIFTING TO SOUTHWEST BY TUESDAY MORNING. EXPECT LIGHT
WINDS AND NEGLIGIBLE WAVES THROUGH TUESDAY NIGHT.
&&
.CLIMATE...
THIS CHILLY SUNDAY MORNING SAW BUFFALO SET A NEW RECORD LOW
TEMPERATURE WITH THE 28 DEGREE READING BREAKING THE OLD RECORD OF
29. THIS IS THE FIRST TIME A RECORD LOW MINIMUM TEMPERATURE HAS
BEEN SET AT THE BUFFALO AIRPORT SINCE MARCH 6 2007.
ROCHESTER NEW YORK ALSO TIED A RECORD LOW THIS MORNING...THE 27
DEGREES TIED THE RECORD LOW VALUE. THIS IS THE FIRST TIME A RECORD
LOW MINIMUM WAS EITHER SET OR TIED AT ROCHESTER SINCE JULY 14 2009.
BUFFALO AND ROCHESTER WILL ALSO HAVE POTENTIAL FOR THEIR FIRST BELOW
NORMAL TEMPERATURE MONTH SINCE MARCH 2011. BOTH BUFFALO AND
ROCHESTER WITH HELP OF THE LAST 10 DAYS OF APRIL BELOW NORMAL MAY
JUST END FINISHING UP A FEW TENTHS OF A DEGREE BELOW NORMAL FOR
APRIL. FINAL STATISTICS WILL BE CALCULATED AFTER THE MONTH
FINISHES.
APRIL`S MONTHLY TEMPERATURE DEPARTURE IS A DRASTIC DIFFERENCE FROM
MARCH 2012 WHEN BOTH CITIES HAD A SIGNIFICANTLY ABOVE NORMAL
TEMPERATURE DEPARTURE. ONLY ONCE IN RECORDED HISTORY HAS THERE BEEN
A COOLER APRIL THAN MARCH AND THAT OCCURRED FOR BUFFALO BACK IN 1946.
THERE IS GOOD POTENTIAL FOR BOTH CITIES TO HAVE A COOLER APRIL
THAN MARCH IN 2012. THROUGH THE 28TH OF APRIL BUFFALO`S AVERAGE
APRIL TEMPERATURE IS 2.1 DEGREES COOLER THAN THE AVERAGE
TEMPERATURE RECORDED IN MARCH 2012. FOR ROCHESTER...WHICH HAS BEEN
SLIGHTLY WARMER THIS MONTH THROUGH THE SAME TIME SPAN...APRIL 2012
HAS BEEN 1.2 DEGREES COOLER THAN MARCH 2012.
BELOW ARE THE YEARS AND TOP FIVE LOWEST SPREADS BETWEEN APRIL
AVERAGE TEMPERATURE AND MARCH AVERAGE TEMPERATURE.
BUFFALO
YEAR APRIL AVG TEMPERATURE MINUS MARCH AVG TEMPERATURE
1946 -0.1
1898 2.3
1907 2.9
1903 3.0
1920 3.8
ROCHESTER
YEAR APRIL AVG TEMPERATURE MINUS MARCH AVG TEMPERATURE
1898 0.8
1946 1.2
1907 2.8
1903 3.0
1995 3.1
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SMITH
NEAR TERM...APFFEL/SMITH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...WCH
MARINE...APFFEL/SMITH/WOOD
CLIMATE...THOMAS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1021 PM EDT WED MAY 2 2012
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL PASS THROUGH THE GREAT LAKES
TONIGHT. HIGH PRESSURE WILL STRENGTHEN ON THURSDAY...LEADING TO
MAINLY DRY WEATHER AND CONTINUED MUCH ABOVE NORMAL TEMPERATURES. A
COLD FRONT WILL SLOWLY SINK SOUTH INTO THE REGION THROUGH THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
UPDATED THE FORECAST TO DECREASE PRECIPITATION CHANCES FOR THE
OVERNIGHT TIME FRAME. THE HRRR IS STILL TRYING TO SHOW A FEW
STORMS DEVELOPING AND MOVING ACROSS EXTREME NORTHERN PORTIONS OF
THE FA. MODELS HAVE BEEN OVERDOING PRECIPITATION TONIGHT AND
CURRENTLY DRY CONDITIONS ARE PRESENT ACROSS THE REGION. ONLY LEFT
A SLIGHT CHANCE OF THUNDERSTORMS IN ACROSS THE EXTREME NORTHERN
LOCATION OF THE FA HOWEVER BELIEVE THE CHANCE FOR PRECIPITATION
WILL BE LOW. MADE MINOR ADJUSTMENTS TO TEMPERATURES TO ACCOUNT FOR
CURRENT TRENDS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
UPPER LEVEL RIDGING WILL STRENGTHEN ON THURSDAY WHICH SHOULD PUT A
MORE SUBSIDENT ATMOSPHERE IN PLACE...ALTHOUGH A DECENT AMOUNT OF
INSTBY WILL CONTINUE TO BE PRESENT. SOME MODELS TRY TO POP A FEW
STORMS BUT THINK THIS THREAT IS PRETTY MINIMAL. WITH GOOD
MIXING...THERE WILL BE SOME CUMULUS DEVELOPMENT BUT STILL PLENTY
OF SUN AND WAA...SO EXPECT ANOTHER DAY OF TEMPERATURES IN THE MID
80S AND PERHAPS UPPER 80S IN THE SE. RECORD HIGHS ARE 87 AT
CVG...89 AT CMH...AND 90 AT DAY. IT WILL BE A LITTLE BREEZY AS
WELL...PARTICULARLY THE NW WHERE A TIGHTER PRESSURE GRADIENT WILL
BE DUE TO LOW PRESSURE OVER THE UPPER GREAT LAKES.
THERE IS SOME MODEL DISAGREEMENT ON WHAT TO DO WITH AN EMBEDDED
VORT MAX OVER THE GULF COAST. THE NAM/GFS TRY TO LIFT THIS ALL THE
WAY INTO WEST VIRGINIA BY THURSDAY EVENING AND OVERNIGHT...WHICH
COULD PROVIDE SOME PCPN TO OUR FAR SE COUNTIES. OTHER MODELS ARE
WEAKER WITH THIS FEATURE AND MAINLY KEEP ITS INFLUENCE OUT OF OUR
AREA. FOR NOW JUST INTRODUCED LOW END POPS IN THE SE DURING
THIS PERIOD. OTHERWISE ANOTHER NIGHT WITH LOWS IN THE MID 60S IS
IN STORE.
HEIGHTS BEGIN TO FALL ON FRIDAY. MODELS ARE IN PRETTY GOOD
AGREEMENT ON BRINGING A SHORTWAVE TROUGH THROUGH THE GREAT LAKES
DURING THE DAY...WHILE A SFC BOUNDARY SLOWLY SINKS SOUTH AS WELL.
DEEP MOISTURE WILL BE ON THE INCREASE...SO EXPECT MORE CLOUDS AND
SHOWERS AND THUNDERSTORMS GRADUALLY WORKING THEIR WAY SOUTH INTO
THE AREA. SHEAR PROFILES WILL ALSO BECOME MORE FAVORABLE WHICH
COULD LEAD TO SOME SEVERE STORMS. THIS IS HIGHLIGHTED IN THE HWO
AND SPC DAY 3 OUTLOOK. ABOVE FACTORS WILL LIMIT DAYTIME HIGHS TO
THE LOWER TO MID 80S. THE NORTH COULD BE COOLER IF STORMS MOVE IN
EARLY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
SATURDAY STARTS OUT WITH THE PREDAWN HOURS AND A FRONT DRAPED W-E
OVER THE OHIO VALLEY PROVIDING A FOCUS FOR EXPECTED SHOWER AND
THUNDERSTORMS. THESE STORMS MAY CONTINUE INTO SATURDAY DAYLIGHT
HOURS AS THE FRONT CONTINUES TO SAG SOUTHWARD TOWARDS THE LOWER OHIO
VALLEY OR NORTHERN TENNESSEE VALLEY. THIS PUSH IS DUE TO BUILDING
HIGH PRESSURE OVER CANADA NORTH OF THE GREAT LAKES.
MODELS DIFFER IN THEIR RESULTS ON SUNDAY BUT THE EUROPEAN DEVELOPS A
WARM FRONT OVER CWA WHILE CANADIEN AND GFS CONTINUE TO BUILD THE
HIGH TO THE NORTHEAST...KEEPING A MORE DRY EASTERLY FLOW OVER CWA
THROUGH SUNDAY AND SUN NIGHT. LOW PRESSURE WILL DEVELOP OVER THE
MIDWEST ON MONDAY AND TRACK TOWARDS THE OHIO VALLEY DURING THE
DAY...COMBINING WITH THE BREAKDOWN OF THE UPPER RIDGE TO INCREASE
THE CHANCE FOR ANOTHER ROUND OF STORMS MONDAY AND MONDAY NIGHT.
THE RESULTANT COLD FRONT CROSSES EARLY TUESDAY AND DRIER AIR SHOULD
REPLACE IT THROUGH MID WEEK AS HIGH PRESSURE BUILDS BEHIND IT WITH
COOLER AND DRIER AIR.
TEMPERATURES THROUGH TUESDAY WILL CONTINUE TO BE UNSEASONABLY WARM
IN THE UPPER 70S TO LOWER 80S WITH MILD NIGHTTIME LOWS IN 55-60
RANGE. AFTER TUESDAY THERE SHOULD BE A BIT COOLER AIR FILTERING
IN...MAKING READINGS MORE TOWARDS SEASONAL NORMALS.
CONFIDENCE IN THE EXTENDED BEYOND SATURDAY REMAINS LOW DUE TO THE
LARGE VARIABILITY IN MODEL GUIDANCE AND RUN TO RUN INCONSISTENCY.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
MAINLY DRY CONDITIONS CAN BE EXPECTED FOR THE TAF PERIOD. A FEW
THUNDERSTORMS MAY DEVELOP ACROSS NORTHERN OHIO AND DROP DOWN INTO
THE KCMH AND KLCK AREA THIS EVENING HOWEVER THE COVERAGE AND
PROBABILITY OF THIS OCCURRING ARE LOW AND THEREFORE HAVE LEFT OUT
OF THE TAF SITES AT THIS TIME. WINDS WILL DECREASE ACROSS THE TAF
SITES OVERNIGHT. SOME FOG WILL BE POSSIBLE AT KLUK FOR A FEW
HOURS. VFR CONDITIONS WILL RETURN BY 14Z AT KLUK. CU WILL DEVELOP
DURING THE DAY ON THURSDAY. WINDS WILL PICK UP AS WELL DURING THE
DAY WITH SOME WIND GUSTS ACROSS THE TAF SITES.
OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY INTO SATURDAY AND AGAIN ON
SUNDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...NOVAK
SHORT TERM...SNYDER
LONG TERM...FRANKS
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
155 PM EDT TUE MAY 1 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL SAG ACROSS THE REGION THIS MORNING WITH
HIGH PRESSURE BRIEFLY BUILDING INTO THE REGION. A WARM FRONT WILL
LIFT NORTHWARD TONIGHT WITH HIGH PRESSURE OVER THE SOUTHEASTERN
UNITED STATES BECOMING THE DOMINATE FEATURE BY THURSDAY. LOW
PRESSURE WILL MOVE ACROSS THE CENTRAL LAKES INTO QUEBEC ON FRIDAY
WITH A COLD FRONT MOVING ACROSS THE REGION BY SATURDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO SHOWERS AND THUNDERSTORMS TO GRIDS BASED ON HRRR AND
TIMING OF PRECIP TO OUR WEST. HRRR A BIT SLOWER INTO WESTERN
COUNTIES OF THE CWA THAN SATELLITE AND RADAR BASED TIMING.
ESSENTIALLY FOLLOWED RADAR BASED TIMING INTO THE WEST AND THEN
CONTINUED THAT ACROSS THE CWA...INTERPOLATING INTO THE OVERNIGHT`S
POPS. ALSO ADJUSTED HIGHS AGAIN BASED ON HRRR.
PREVIOUS DISCUSSION...
A WEAK COLD FRONT WILL SAG ACROSS THE REGION THIS MORNING WITH
HIGH PRESSURE AT LEAST BRIEFLY TAKING CONTROL. THE GREATEST
UNCERTAINTY FOR THE DAY IS THE AMOUNT OF CLOUD COVER THAT WILL
PERSIST IN THE WAKE OF THE FRONT. THIS WILL HAVE SIGNIFICANT
IMPLICATIONS ON HIGH TEMPERATURES. AT THIS POINT IT APPEARS WE
WILL SEE AT LEAST SOME SUNSHINE FOR THE AFTERNOON WITH HIGHS
GENERALLY IN THE 70 TO 75 RANGE...COOLER ACROSS NW PA. HOWEVER IF
THE CLOUDS PERSIST THEN WE WILL NEED TO TRIM 4 TO 6 DEGREES FROM
THE CURRENT FORECAST.
THERE HAS BEEN A FEW AREAS OF DRIZZLE/SPRINKLES AS THE WEAK FRONT
MOVES ACROSS NW OH. BELIEVE THIS WILL CONTINUE AS IT SAGS TO THE
SOUTHEAST. PLAN TO COVER THE DRIZZLE AND PATCHY FOG WITH SHORT
TERM FORECASTS IF IT CONTINUES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
A WARM FRONT WILL MOVE TOWARD THE REGION TONIGHT WITH INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS NEAR AND NORTH OF IT. SHEAR
AND INSTABILITY LOOK RATHER WEAK SO WILL NOT MENTION ANY SEVERE
THUNDERSTORMS FOR THE OVERNIGHT HOURS. THE CHANCES OF
THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY AS WE AWAIT A SURGE OF
HOT AND HUMID AIR TO ARRIVE ON THURSDAY. THURSDAY SHOULD END UP
BEING A DRY DAY WITH HIGHS SURGING WELL INTO THE 80S. STILL LOOKS
AS IF A FEW LOCATIONS MAY REACH 90. AS A COLD FRONT MOVES CLOSER
TO THE REGION LATE FRIDAY INTO FRIDAY NIGHT THERE WILL ONCE AGAIN
BE AN INCREASE OF SHOWERS AND THUNDERSTORMS. FRIDAY EVENING INTO THE
OVERNIGHT HOURS MAY BRING A ROUND OF SEVERE THUNDERSTORMS. MORE ON
THIS THROUGH THE WEEK.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
BELOW NORMAL CONFIDENCE FOR THE WEEKEND FORECAST WITH CONSIDERABLE
DIFFERENCES BETWEEN THE LONG RANGE MODELS. THE GFS IS AN OUTLIER
WITH A STRONG UPPER LEVEL TROUGH PUSHING SOUTH ACROSS QUEBEC ON
SUNDAY WHILE THE ECMWF/GEM/UKMET MAINTAIN AN UPPER LEVEL RIDGE OVER
THE GREAT LAKES REGION. HAVE TRENDED THE FORECAST TOWARDS THE BETTER
CONSENSUS...MAINTAING A WARM AIRMASS OVER THE REGION WITH A
CONTINUED CHANCE OF THUNDERSTORMS.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A RATHER ACTIVE WEATHER PATTERN EXPECTED THROUGH THE TAF PERIOD
ACROSS ALL SITES. A FRONTAL BOUNDARY IS LOCATED OVER SOUTHERN OHIO
THIS AFTERNOON WITH SURFACE HIGH PRESSURE OVER LAKE ERIE.
MEANWHILE... A THUNDERSTORM COMPLEX OVER INDIANA IS EXPECTED TO
CONTINUE MOVING EAST NORTHEAST THROUGH THIS EVENING AND INTO
TONIGHT WHICH IS EXPECTED TO BRING THE CHANCES OF TS ESPECIALLY
ACROSS WESTERN SITES...BUT UNSURE AS TO HOW FAR EAST THUNDERSTORMS
EMBEDDED IN THE RAIN WILL PERSIST. HOWEVER...LOOKS LIKELY THAT
RAIN ASSOCIATED WITH THIS WILL MOVE ACROSS SITES THIS EVENING AND
INTO TONIGHT. ALSO THROUGH TONIGHT...THE BOUNDARY SOUTH OF THE
AREA WILL BEGIN MOVING NORTH AS A WARM FRONT AND CROSS MOST
LOCATIONS BY 18Z WED. AFTER THE RAIN MOVES THROUGH TONIGHT
INCLUDED ADDITIONAL PERIODS OF IFR CONDITIONS. MODELS NOT IN
COMPLETE AGREEMENT ON THIS SOLUTION BUT WITH THE FRONT PUSHING
NORTHWARD THINKING THAT THERE IS AT LEAST THE CHANCE FOR SOME IFR
ACROSS SITES TONIGHT AND PERHAPS EVEN INTO WED MORNING. AS THE
FRONT MOVES NORTH OF SITES SOUTHERLY WINDS WILL BECOME MORE
PREDOMINATE AND CIG EXPECTED TO BECOME VFR TOWARD THE END OF THE
FCST PERIOD. ERI WILL BE MOST LIKELY TO CONTINUE IFR THROUGH
MIDDAY WED.
.OUTLOOK...NON-VFR CONDITIONS POSSIBLE THURSDAY MORNING....THEN
AGAIN IN CONVECTION FRIDAY AFTERNOON AND EVENING.
&&
.MARINE...
WEAK LOW PRESSURE NEAR EASTERN LAKE ERIE WILL TRACK TO THE EAST
COAST TODAY. LIGHT SOUTHERLY WINDS WILL DEVELOP IN THE WAKE OF THIS
SYSTEM THIS AFTERNOON...PUSHING A WARM FRONT NORTH ACROSS THE LAKE
OVERNIGHT. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL LIKELY
ACCOMPANY THE FRONT. A VERY WARM AIRMASS WILL BE OVER THE LAKE FOR
THE END OF THE WEEK WITH A WEAK FRONTAL BOUNDARY SAGGING SOUTH
DURING THE FRIDAY TO SATURDAY TIME FRAME. THIS FRONT WILL AGAIN BE A
FOCUS FOR SHOWERS AND THUNDERSTORMS.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...TK/MULLEN
SHORT TERM...MULLEN
LONG TERM...KEC
AVIATION...ABE
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1235 PM EDT TUE MAY 1 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL SAG ACROSS THE REGION THIS MORNING WITH
HIGH PRESSURE BRIEFLY BUILDING INTO THE REGION. A WARM FRONT WILL
LIFT NORTHWARD TONIGHT WITH HIGH PRESSURE OVER THE SOUTHEASTERN
UNITED STATES BECOMING THE DOMINATE FEATURE BY THURSDAY. LOW
PRESSURE WILL MOVE ACROSS THE CENTRAL LAKES INTO QUEBEC ON FRIDAY
WITH A COLD FRONT MOVING ACROSS THE REGION BY SATURDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED TO SHOWERS AND THUNDERSTORMS TO GRIDS BASED ON HRRR AND
TIMING OF PRECIP TO OUR WEST. HRRR A BIT SLOWER INTO WESTERN
COUNTIES OF THE CWA THAN SATELLITE AND RADAR BASED TIMING.
ISSENTIALLY FOLLOWED RADAR BASED TIMING INTO THE WEST AND THEN
CONTINUED THAT ACROSS THE CWA...INTERPOLATING INTO THE OVERNIGHT`S
POPS. ALSO ADJUSTED HIGHS AGAIN BASED ON HRRR.
PREVIOUS DISCUSSION...
A WEAK COLD FRONT WILL SAG ACROSS THE REGION THIS MORNING WITH
HIGH PRESSURE AT LEAST BRIEFLY TAKING CONTROL. THE GREATEST
UNCERTAINTY FOR THE DAY IS THE AMOUNT OF CLOUD COVER THAT WILL
PERSIST IN THE WAKE OF THE FRONT. THIS WILL HAVE SIGNIFICANT
IMPLICATIONS ON HIGH TEMPERATURES. AT THIS POINT IT APPEARS WE
WILL SEE AT LEAST SOME SUNSHINE FOR THE AFTERNOON WITH HIGHS
GENERALLY IN THE 70 TO 75 RANGE...COOLER ACROSS NW PA. HOWEVER IF
THE CLOUDS PERSIST THEN WE WILL NEED TO TRIM 4 TO 6 DEGREES FROM
THE CURRENT FORECAST.
THERE HAS BEEN A FEW AREAS OF DRIZZLE/SPRINKLES AS THE WEAK FRONT
MOVES ACROSS NW OH. BELIEVE THIS WILL CONTINUE AS IT SAGS TO THE
SOUTHEAST. PLAN TO COVER THE DRIZZLE AND PATCHY FOG WITH SHORT
TERM FORECASTS IF IT CONTINUES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
A WARM FRONT WILL MOVE TOWARD THE REGION TONIGHT WITH INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS NEAR AND NORTH OF IT. SHEAR
AND INSTABILITY LOOK RATHER WEAK SO WILL NOT MENTION ANY SEVERE
THUNDERSTORMS FOR THE OVERNIGHT HOURS. THE CHANCES OF
THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY AS WE AWAIT A SURGE OF
HOT AND HUMID AIR TO ARRIVE ON THURSDAY. THURSDAY SHOULD END UP
BEING A DRY DAY WITH HIGHS SURGING WELL INTO THE 80S. STILL LOOKS
AS IF A FEW LOCATIONS MAY REACH 90. AS A COLD FRONT MOVES CLOSER
TO THE REGION LATE FRIDAY INTO FRIDAY NIGHT THERE WILL ONCE AGAIN
BE AN INCREASE OF SHOWERS AND THUNDERSTORMS. FRIDAY EVENING INTO THE
OVERNIGHT HOURS MAY BRING A ROUND OF SEVERE THUNDERSTORMS. MORE ON
THIS THROUGH THE WEEK.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
BELOW NORMAL CONFIDENCE FOR THE WEEKEND FORECAST WITH CONSIDERABLE
DIFFERENCES BETWEEN THE LONG RANGE MODELS. THE GFS IS AN OUTLIER
WITH A STRONG UPPER LEVEL TROUGH PUSHING SOUTH ACROSS QUEBEC ON
SUNDAY WHILE THE ECMWF/GEM/UKMET MAINTAIN AN UPPER LEVEL RIDGE OVER
THE GREAT LAKES REGION. HAVE TRENDED THE FORECAST TOWARDS THE BETTER
CONSENSUS...MAINTAING A WARM AIRMASS OVER THE REGION WITH A
CONTINUED CHANCE OF THUNDERSTORMS.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
WEAK LOW PRESSURE HAS SLID EAST INTO NEW YORK AND PENNSYLVANIA THIS
MORNING WITH AMPLE LOW LEVEL MOISTURE IN PLACE BEHIND IT. A FEW
LIGHT SHOWERS/DRIZZLE WILL CONTINUE TO IMPACT YNG/ERI THROUGH 14Z
BEFORE STARTING TO DRY OUT. ELSEWHERE CONDITIONS HAVE VARIED BETWEEN
IFR/MVFR EARLY THIS MORNING...BUT CEILINGS SHOULD LIFT INTO THE MVFR
RANGE BY AROUND 15Z. FORECAST CHALLENGE IS IF AND WHEN LOW CLOUDS
WILL SCATTER OUT TODAY. MODELS SOUNDINGS SHOW MOISTURE DEPTH
DECREASING WITH CLOUDS SCATTERING OUT BY EARLY AFTERNOON. HAVE BEEN
JUST A TOUCH MORE PESSIMISTIC WITH THE CLEARING TREND GIVEN HIGH
CLOUDS ARE ALREADY ARRIVING FROM THE WEST...BUT STILL EXPECT
RETURN TO VFR THIS AFTERNOON. THE WARM FRONT WILL LIFT NORTH TOWARDS THE
REGION TONIGHT WITH SHOWERS AND SCATTERED THUNDERSTORMS ARRIVING
AFTER 04Z WEST/08Z EAST.
.OUTLOOK...NON-VFR CONDITIONS POSSIBLE WITH SHOWERS AND
THUNDERSTORMS INTO WEDNESDAY MORNING...THEN AGAIN FROM FRIDAY
INTO SATURDAY.
&&
.MARINE...
WEAK LOW PRESSURE NEAR EASTERN LAKE ERIE WILL TRACK TO THE EAST
COAST TODAY. LIGHT SOUTHERLY WINDS WILL DEVELOP IN THE WAKE OF THIS
SYSTEM THIS AFTERNOON...PUSHING A WARM FRONT NORTH ACROSS THE LAKE
OVERNIGHT. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL LIKELY
ACCOMPANY THE FRONT. A VERY WARM AIRMASS WILL BE OVER THE LAKE FOR
THE END OF THE WEEK WITH A WEAK FRONTAL BOUNDARY SAGGING SOUTH
DURING THE FRIDAY TO SATURDAY TIME FRAME. THIS FRONT WILL AGAIN BE A
FOCUS FOR SHOWERS AND THUNDERSTORMS.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...TK/MULLEN
SHORT TERM...MULLEN
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1101 AM EDT TUE MAY 1 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL SAG ACROSS THE REGION THIS MORNING WITH
HIGH PRESSURE BRIEFLY BUILDING INTO THE REGION. A WARM FRONT WILL
LIFT NORTHWARD TONIGHT WITH HIGH PRESSURE OVER THE SOUTHEASTERN
UNITED STATES BECOMING THE DOMINATE FEATURE BY THURSDAY. LOW
PRESSURE WILL MOVE ACROSS THE CENTRAL LAKES INTO QUEBEC ON FRIDAY
WITH A COLD FRONT MOVING ACROSS THE REGION BY SATURDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED FIRST TO ADD FOG TO LAKESHORE COUNTIES AND REALIGN GRIDS
FOR SPRINKLES AND CLOUDS. ALSO ADJUSTED HIGHS. UPDATED AGAIN TO
REFLECT AT LEAST SOME LIMITED SUN IN PLACES FOR THE EARLY
AFTERNOON ALTHOUGH WILL STILL BE MOSTLY CLOUDY ON BALANCE. CLOUDS
WILL INCREASE AGAIN MID/LATE AFTERNOON AS DEBRIS FROM ILLINOIS
CONVECTION MOVE INTO THE AREA. HIGHS WILL ALSO BE TRICKY WITH
CLOUDS...SOME SUN AND A LIGHT NORTH WIND OFF THE LAKE. FOLLOWED
HRRR MODEL TEMPS WITH MINOR ADJUSTMENTS. ALSO HRRR MODEL SHOWS
CONVECTION MOVING ACROSS THE AREA LATE THIS AFTERNOON SO WILL BE
LOOKING AT THAT AND THE EXPECTED TIMING FOR NEXT UPDATE.
PREVIOUS...HAVE DECIDED TO ADD SPRINKLES TO THE FORECAST. HOWEVER
MUCH IT MAY END UP BEING IN THE FORM OF DRIZZLE. STILL HAVE
CONCERNS ABOUT HOW FAST THE CLOUD COVER WILL LIFT...ESPECIALLY
WITH THE MIDDLE AND HIGH LEVEL CONVECTIVE DEBRIS FROM MISSOURI
MOVING TOWARD THE REGION.
PREVIOUS DISCUSSION...
A WEAK COLD FRONT WILL SAG ACROSS THE REGION THIS MORNING WITH
HIGH PRESSURE AT LEAST BRIEFLY TAKING CONTROL. THE GREATEST
UNCERTAINTY FOR THE DAY IS THE AMOUNT OF CLOUD COVER THAT WILL
PERSIST IN THE WAKE OF THE FRONT. THIS WILL HAVE SIGNIFICANT
IMPLICATIONS ON HIGH TEMPERATURES. AT THIS POINT IT APPEARS WE
WILL SEE AT LEAST SOME SUNSHINE FOR THE AFTERNOON WITH HIGHS
GENERALLY IN THE 70 TO 75 RANGE...COOLER ACROSS NW PA. HOWEVER IF
THE CLOUDS PERSIST THEN WE WILL NEED TO TRIM 4 TO 6 DEGREES FROM
THE CURRENT FORECAST.
THERE HAS BEEN A FEW AREAS OF DRIZZLE/SPRINKLES AS THE WEAK FRONT
MOVES ACROSS NW OH. BELIEVE THIS WILL CONTINUE AS IT SAGS TO THE
SOUTHEAST. PLAN TO COVER THE DRIZZLE AND PATCHY FOG WITH SHORT
TERM FORECASTS IF IT CONTINUES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
A WARM FRONT WILL MOVE TOWARD THE REGION TONIGHT WITH INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS NEAR AND NORTH OF IT. SHEAR
AND INSTABILITY LOOK RATHER WEAK SO WILL NOT MENTION ANY SEVERE
THUNDERSTORMS FOR THE OVERNIGHT HOURS. THE CHANCES OF
THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY AS WE AWAIT A SURGE OF
HOT AND HUMID AIR TO ARRIVE ON THURSDAY. THURSDAY SHOULD END UP
BEING A DRY DAY WITH HIGHS SURGING WELL INTO THE 80S. STILL LOOKS
AS IF A FEW LOCATIONS MAY REACH 90. AS A COLD FRONT MOVES CLOSER
TO THE REGION LATE FRIDAY INTO FRIDAY NIGHT THERE WILL ONCE AGAIN
BE AN INCREASE OF SHOWERS AND THUNDERSTORMS. FRIDAY EVENING INTO THE
OVERNIGHT HOURS MAY BRING A ROUND OF SEVERE THUNDERSTORMS. MORE ON
THIS THROUGH THE WEEK.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
BELOW NORMAL CONFIDENCE FOR THE WEEKEND FORECAST WITH CONSIDERABLE
DIFFERENCES BETWEEN THE LONG RANGE MODELS. THE GFS IS AN OUTLIER
WITH A STRONG UPPER LEVEL TROUGH PUSHING SOUTH ACROSS QUEBEC ON
SUNDAY WHILE THE ECMWF/GEM/UKMET MAINTAIN AN UPPER LEVEL RIDGE OVER
THE GREAT LAKES REGION. HAVE TRENDED THE FORECAST TOWARDS THE BETTER
CONSENSUS...MAINTAING A WARM AIRMASS OVER THE REGION WITH A
CONTINUED CHANCE OF THUNDERSTORMS.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
WEAK LOW PRESSURE HAS SLID EAST INTO NEW YORK AND PENNSYLVANIA THIS
MORNING WITH AMPLE LOW LEVEL MOISTURE IN PLACE BEHIND IT. A FEW
LIGHT SHOWERS/DRIZZLE WILL CONTINUE TO IMPACT YNG/ERI THROUGH 14Z
BEFORE STARTING TO DRY OUT. ELSEWHERE CONDITIONS HAVE VARIED BETWEEN
IFR/MVFR EARLY THIS MORNING...BUT CEILINGS SHOULD LIFT INTO THE MVFR
RANGE BY AROUND 15Z. FORECAST CHALLENGE IS IF AND WHEN LOW CLOUDS
WILL SCATTER OUT TODAY. MODELS SOUNDINGS SHOW MOISTURE DEPTH
DECREASING WITH CLOUDS SCATTERING OUT BY EARLY AFTERNOON. HAVE BEEN
JUST A TOUCH MORE PESSIMISTIC WITH THE CLEARING TREND GIVEN HIGH
CLOUDS ARE ALREADY ARRIVING FROM THE WEST...BUT STILL EXPECT
RETURN TO VFR THIS AFTERNOON. THE WARM FRONT WILL LIFT NORTH TOWARDS THE
REGION TONIGHT WITH SHOWERS AND SCATTERED THUNDERSTORMS ARRIVING
AFTER 04Z WEST/08Z EAST.
.OUTLOOK...NON-VFR CONDITIONS POSSIBLE WITH SHOWERS AND
THUNDERSTORMS INTO WEDNESDAY MORNING...THEN AGAIN FROM FRIDAY
INTO SATURDAY.
&&
.MARINE...
WEAK LOW PRESSURE NEAR EASTERN LAKE ERIE WILL TRACK TO THE EAST
COAST TODAY. LIGHT SOUTHERLY WINDS WILL DEVELOP IN THE WAKE OF THIS
SYSTEM THIS AFTERNOON...PUSHING A WARM FRONT NORTH ACROSS THE LAKE
OVERNIGHT. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL LIKELY
ACCOMPANY THE FRONT. A VERY WARM AIRMASS WILL BE OVER THE LAKE FOR
THE END OF THE WEEK WITH A WEAK FRONTAL BOUNDARY SAGGING SOUTH
DURING THE FRIDAY TO SATURDAY TIME FRAME. THIS FRONT WILL AGAIN BE A
FOCUS FOR SHOWERS AND THUNDERSTORMS.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...TK/MULLEN
SHORT TERM...MULLEN
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
652 AM EDT TUE MAY 1 2012
.SYNOPSIS...
A WARM FRONT WILL MOVE NORTHEAST THROUGH THE REGION TODAY...BRINGING
A CHANCE OF SHOWERS AND THUNDERSTORMS. PRECIPITATION WILL CONTINUE
TO BE POSSIBLE THROUGH WEDNESDAY...BEFORE HIGH PRESSURE BUILDS IN ON
THURSDAY AND PROVIDES VERY WARM TEMPERATURES WITH DRY CONDITIONS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A BOUNDARY IS CURRENTLY RESIDING JUST SOUTH OF THE FORECAST
AREA...ALTHOUGH IT IS NOT TERRIBLY EASY TO PICK UP ON SURFACE
OBSERVATIONS. THE FLOW IS SLIGHTLY MORE SOUTHERLY SOUTH OF THE
CWA...BUT THE FEATURE IS PERHAPS EASIEST TO PICK OUT ON MODEL
1000MB-500MB RH FIELDS...WHERE THERE IS A SHARP CONTRAST WITH THE
DRIER HIGH PRESSURE OVER THE SOUTHERN GREAT LAKES AND NORTHERN
OHIO VALLEY.
A DRY FORECAST WILL BEGIN THE PERIOD...WITH ACTIVITY ASSOCIATED
WITH THIS FRONT RATHER SCATTERED AND ALL WELL SOUTH OF THE REGION.
HOWEVER...THE BOUNDARY WILL PROGRESS NORTH INTO THE REGION AS A
WARM FRONT...AND ACTIVITY TO THE WEST AND SOUTHWEST WILL BEGIN TO
AFFECT THE AREA BY AFTERNOON. EVIDENCE OF THIS IS VISIBLE WITH THE
CLUSTER OF STORMS OVER NORTHWESTERN TENNESSEE...WHICH HAS SOMEWHAT
OF A NORTHWARD COMPONENT TO ITS MOTION. THE HRRR DOES SHOW THIS
CLUSTER...BUT ITS PLACEMENT AND TIMING ARE NOT TOTALLY CORRECT.
OVERALL THE POP FORECAST HAS NOT CHANGED TOO MUCH FROM THE
PREVIOUS GRIDS...WITH A SLIGHTLY SLOWER ONSET OF THE HIGHER CHANCE
POPS UNTIL LATER IN THE DAY...BUT MAINTAINING A LOW CHANCE /
SLIGHT CHANCE EARLIER IN THE DAY AS THE FRONT MOVES NORTH. THE
BEST CHANCES FOR PRECIPITATION APPEAR TO COME DURING THE EVENING
(DETAILED BELOW IN THE SHORT TERM SECTION).
THE MAX TEMP FORECAST IS SLIGHTLY CONVOLUTED TODAY...GIVEN THE
CLOUDS AND PRECIPITATION THAT WILL AFFECT THE WHOLE AREA...BUT
ESPECIALLY THE SOUTH AND SOUTHWEST DURING THE DAY TIME HOURS. WITH
THE POSSIBILITY OF MORE SUN IN THE NORTH AND NORTHEAST...THIS MAY
OFFSET THE TYPICAL TEMPERATURE DISTRIBUTION TO RESULT IN SIMILAR
HIGHS ACROSS THE WHOLE CWA TODAY. THE CLOUDS AND EVENTUAL
PRECIPITATION SHOULD BE ENOUGH TO HOLD THINGS IN THE 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
BY LATE AFTERNOON AND INTO THE EVENING...ATTENTION WILL BE TURNED
TO CONVECTION FIRING ON THE ADVANCING WARM FRONT...AS WELL AS
ACTIVITY MOVING IN FROM THE WEST (A PARTIAL DESCENDANT OF THE
CURRENT ACTIVITY IN MISSOURI AND OKLAHOMA). A SHORTWAVE WILL MOVE
INTO THE AREA AND INTERACT WITH AN AIRMASS THAT SHOULD BE
DESTABILIZING TO SOME EXTENT. MIXED LAYER CAPE VALUES OF AROUND
1000 J/KG WILL BE POSSIBLE IN THE SOUTH...WHERE MID LEVEL LAPSE
RATES ARE SLIGHTLY STEEPER AND BOUNDARY LAYER MOISTURE WILL BE
INCREASING. LIFT PROVIDED BY THE SHORTWAVE AND SOME MODEST (THOUGH
NOT BY ANY MEANS INTENSE) CONVERGENCE ON A LOW LEVEL JET WILL
ALLOW FOR STORM DEVELOPMENT. SHEAR IS NOT ESPECIALLY STRONG...BUT
0-6KM BULK SHEAR OF 40 KNOTS WILL ALLOW FOR SOME ORGANIZATION. THE
SEVERE THREAT APPEARS GREATEST IN THE SOUTH...WHERE GREATER
INSTABILITY WILL BE MORE LIKELY. HOWEVER...THE PRESENCE OF SAID
INSTABILITY MAY BE DIMINISHED IF RAIN OCCURS AHEAD OF THE MORE
INTENSE FORCING.
BEYOND THE PASSAGE OF THE SYSTEM THIS EVENING...THE CONVECTIVE
FORECAST BECOMES RATHER DIFFICULT IN TERMS OF SPECIFIC TIMING AND
PLACEMENT. SMEARY MODEL QPF BEHIND THE TUESDAY NIGHT SYSTEM IS
TOUGH TO PLACE WITH REGARDS TO FORCING SIGNALS...ESPECIALLY AS MID
LEVEL RIDGING CONTINUES TO BUILD INTO THE AREA DURING THIS TIME
FRAME. WILL KEEP POPS RATHER LIMITED ON WEDNESDAY...BEFORE GOING
DRY BY WEDNESDAY AFTERNOON IN THE SOUTHWEST AND WEDNESDAY NIGHT
ELSEWHERE. BY THIS POINT...MOST OF THE MODELS ARE DEPICTING
FORCING WELL NORTH OF THE CWA AS THE WARM SECTOR ESTABLISHES
ITSELF OVER THE OHIO VALLEY. ANOTHER WRENCH IN THE SOLUTION
INVOLVES THE POSSIBILITY OF SOME OF THE ACTIVITY OVER MICHIGAN
TURNING SOUTH AND PUNCHING THROUGH THE RIDGE INTO CENTRAL OHIO ON
WEDNESDAY NIGHT. THOUGH IT IS NOT AN IMPOSSIBILITY...IT SEEMS LIKE
AN UNLIKELY SOLUTION...AND A DRY FORECAST WILL BE MAINTAINED.
AFTER A FULL DAY IN THE WARM SECTOR ON THURSDAY...FLATTENING
HEIGHTS WILL ALLOW FOR A RETURN OF PRECIPITATION CHANCES BY
FRIDAY. THIS HAS BEEN SLOWED DOWN SLIGHTLY FOR THIS FORECAST
PACKAGE...FOCUSING MAINLY ON FRIDAY NIGHT.
TEMPERATURES THROUGH THE WEEK WILL BE VERY WARM...POSSIBLY TO NEAR
RECORD VALUES. THE WARMEST DAY OF THE WEEK FOR THE WHOLE AREA
APPEARS TO BE THURSDAY...WITH LITTLE TO NO CHANCE OF
PRECIPITATION...PLENTY OF SUNSHINE...AND SOUTHWESTERLY FLOW IN A
WELL MIXED BOUNDARY LAYER. WITH A SLIGHT SLOW DOWN IN TIMING FOR
THE NEXT WEATHER SYSTEM ON FRIDAY...SIMILAR CONDITIONS ARE NOW
ALSO EXPECTED TO PERSIST FOR THE SOUTHEASTERN FORECAST AREA ON
FRIDAY. ALTHOUGH THIS FORECAST PACKAGE WILL NOT TAKE THE LEAP...A
90 DEGREE READING IN THE FAR SOUTH ON THURSDAY OR FRIDAY SEEMS
LIKE A LEGITIMATE POSSIBILITY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
SHORT WAVE ENERGY WILL BE PUSHING EAST OF THE AREA AT THE START OF
THE PERIOD AND THIS SHOULD LEAD TO A DECREASING CHANCE OF
SHOWERS/THUNDERSTORMS THROUGH WEDNESDAY MORNING. MID LEVEL RIDGING
WILL THEN BUILD INTO THE REGION THROUGH THURSDAY. THIS WILL LEAD TO
RISING HEIGHTS AND 8H TEMPS PUSHING UP INTO THE 16 TO 18 DEGREE
CELSIUS RANGE BY THURSDAY AFTERNOON. AS A RESULT...EXPECT A DECENT
WARM UP THROUGH MID WEEK WITH HIGHS BOTH WEDNESDAY AND THURSDAY WELL
INTO THE 80S.
SOME MODEL DIFFERENCES THEN EXIST WITH HOW FAST/HOW MUCH THE RIDGE
WILL BREAK DOWN THROUGH THE END OF THE WEEK AND AS A RESULT...THE
TIMING AND PLACEMENT OF A COLD FRONT THAT MAY SAG DOWN INTO THE
AREA. THE 30.00Z ECMWF WAS THE SLOWEST WITH THIS AND A QUICK LOOK AT
THE 30.12Z ECMWF LOOKS LIKE IT IS EVEN SLOWER AND STRONGER WITH THE
RIDGE. BASED ON THESE TRENDS...WILL SLOW DOWN THE ONSET OF PCPN
THURSDAY NIGHT INTO FRIDAY. WILL THEN ALLOW FOR THE FRONT TO PUSH
DOWN INTO THE AREA THROUGH THE END OF THE WEEK...BUT BASED ON THE
LATEST ECMWF...NOT SURE HOW FAR IT WILL ACTUALLY GET. WILL THEREFORE
LINGER AT LEAST LOW POPS ALL THE WAY INTO SUNDAY. THE 30.12Z GFS IS
BRINGING CONSIDERABLY COOLER TEMPERATURES BEHIND THE FRONT THIS
WEEKEND BUT AGAIN...THE ECMWF IS TRENDING SLOWER/WARMER. WILL GO
AHEAD AND TAKE A BLEND OF THE TWO WITH MORE OF AN EMPHASIS TOWARD
THE WARMER ECMWF THROUGH EARLY NEXT WEEK.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
DUE TO THE RECENT RAINFALL...THE LOW LEVELS OF THE ATMOSPHERE REMAIN
MOIST THIS MORNING. THIS HAS RESULTED IN A POTPURRI OF LOW LEVEL
CLOUDS ACROSS THE REGION WITH CIGS VARYING FROM IFR TO VFR. VSBYS
FOR THE MOST PART WERE MVFR. WILL HOLD ON TO SOME IFR/MVFR CIGS
THROUGH THE FIRST PART OF THE TAF AND THEN SUSPECT THAT CIGS WILL
RISE TO VFR BY LATE MORNING OR EARLY AFTN ALONG WITH A DISSIPATION
OF MVFR VSBYS.
THEREAFTER...A WARM FRONT WILL LIFT NE THROUGH THE REGION THIS
AFTERNOON AND OVERNIGHT. THIS FEATURE WILL COMBINE WITH AN UPPER
LEVEL DISTURBANCE ALOFT TO PRODUCE SHOWERS AND THUNDERSTORMS. SOME
SCATTERED SHOWER/THUNDERSTORM ACTIVITY MAY DEVELOP ACRS THE SW
CWFA BY AS EARLY AS 18Z AS THE WARM FRONT ADVANCES NE.
HOWEVER...TAF WISE...HAVE DECIDED TO FOCUS ON THE MORE WIDESPREAD
SHOWER/EMBEDDED THUNDERSTORMS EXPECTED LATE THIS AFTERNOON INTO
THE OVERNIGHT HOURS. IT IS TOO EARLY AT THIS TIME TO PINPOINT
EXACT TIMING AND DURATION OF THUNDERSTORMS SO HAVE USED THE VCTS
DESCRIPTOR ALONG WITH PREDOMINATE MVFR VSBYS IN SHOWERS. OF
COURSE...WHERE THUNDERSTORMS OCCUR...LOCAL MVFR CIGS AND LOCAL IFR
VSBYS WILL BE POSSIBLE. PCPN SHOULD DECREASE FROM SW TO NE
OVERNIGHT AS THE DISTURBANCE AND WARM FRONT MOVE OFF TO THE NE.
HAVE PLACED SOME MVFR CIGS/VSBYS AT THE TAFS ONCE THE MAIN BULK
OF PCPN HAS PUSHED OFF TO THE EAST ALTHOUGH LOWER CONDITIONS COULD
DEVELOP BUT CONFIDENCE IS NOT HIGH AT THIS TIME.
OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY AND SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
432 AM EDT TUE MAY 1 2012
.SYNOPSIS...
A WARM FRONT WILL MOVE NORTHEAST THROUGH THE REGION TODAY...BRINGING
A CHANCE OF SHOWERS AND THUNDERSTORMS. PRECIPITATION WILL CONTINUE
TO BE POSSIBLE THROUGH WEDNESDAY...BEFORE HIGH PRESSURE BUILDS IN ON
THURSDAY AND PROVIDES VERY WARM TEMPERATURES WITH DRY CONDITIONS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A BOUNDARY IS CURRENTLY RESIDING JUST SOUTH OF THE FORECAST
AREA...ALTHOUGH IT IS NOT TERRIBLY EASY TO PICK UP ON SURFACE
OBSERVATIONS. THE FLOW IS SLIGHTLY MORE SOUTHERLY SOUTH OF THE
CWA...BUT THE FEATURE IS PERHAPS EASIEST TO PICK OUT ON MODEL
1000MB-500MB RH FIELDS...WHERE THERE IS A SHARP CONTRAST WITH THE
DRIER HIGH PRESSURE OVER THE SOUTHERN GREAT LAKES AND NORTHERN
OHIO VALLEY.
A DRY FORECAST WILL BEGIN THE PERIOD...WITH ACTIVITY ASSOCIATED
WITH THIS FRONT RATHER SCATTERED AND ALL WELL SOUTH OF THE REGION.
HOWEVER...THE BOUNDARY WILL PROGRESS NORTH INTO THE REGION AS A
WARM FRONT...AND ACTIVITY TO THE WEST AND SOUTHWEST WILL BEGIN TO
AFFECT THE AREA BY AFTERNOON. EVIDENCE OF THIS IS VISIBLE WITH THE
CLUSTER OF STORMS OVER NORTHWESTERN TENNESSEE...WHICH HAS SOMEWHAT
OF A NORTHWARD COMPONENT TO ITS MOTION. THE HRRR DOES SHOW THIS
CLUSTER...BUT ITS PLACEMENT AND TIMING ARE NOT TOTALLY CORRECT.
OVERALL THE POP FORECAST HAS NOT CHANGED TOO MUCH FROM THE
PREVIOUS GRIDS...WITH A SLIGHTLY SLOWER ONSET OF THE HIGHER CHANCE
POPS UNTIL LATER IN THE DAY...BUT MAINTAINING A LOW CHANCE /
SLIGHT CHANCE EARLIER IN THE DAY AS THE FRONT MOVES NORTH. THE
BEST CHANCES FOR PRECIPITATION APPEAR TO COME DURING THE EVENING
(DETAILED BELOW IN THE SHORT TERM SECTION).
THE MAX TEMP FORECAST IS SLIGHTLY CONVOLUTED TODAY...GIVEN THE
CLOUDS AND PRECIPITATION THAT WILL AFFECT THE WHOLE AREA...BUT
ESPECIALLY THE SOUTH AND SOUTHWEST DURING THE DAY TIME HOURS. WITH
THE POSSIBILITY OF MORE SUN IN THE NORTH AND NORTHEAST...THIS MAY
OFFSET THE TYPICAL TEMPERATURE DISTRIBUTION TO RESULT IN SIMILAR
HIGHS ACROSS THE WHOLE CWA TODAY. THE CLOUDS AND EVENTUAL
PRECIPITATION SHOULD BE ENOUGH TO HOLD THINGS IN THE 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
BY LATE AFTERNOON AND INTO THE EVENING...ATTENTION WILL BE TURNED
TO CONVECTION FIRING ON THE ADVANCING WARM FRONT...AS WELL AS
ACTIVITY MOVING IN FROM THE WEST (A PARTIAL DESCENDANT OF THE
CURRENT ACTIVITY IN MISSOURI AND OKLAHOMA). A SHORTWAVE WILL MOVE
INTO THE AREA AND INTERACT WITH AN AIRMASS THAT SHOULD BE
DESTABILIZING TO SOME EXTENT. MIXED LAYER CAPE VALUES OF AROUND
1000 J/KG WILL BE POSSIBLE IN THE SOUTH...WHERE MID LEVEL LAPSE
RATES ARE SLIGHTLY STEEPER AND BOUNDARY LAYER MOISTURE WILL BE
INCREASING. LIFT PROVIDED BY THE SHORTWAVE AND SOME MODEST (THOUGH
NOT BY ANY MEANS INTENSE) CONVERGENCE ON A LOW LEVEL JET WILL
ALLOW FOR STORM DEVELOPMENT. SHEAR IS NOT ESPECIALLY STRONG...BUT
0-6KM BULK SHEAR OF 40 KNOTS WILL ALLOW FOR SOME ORGANIZATION. THE
SEVERE THREAT APPEARS GREATEST IN THE SOUTH...WHERE GREATER
INSTABILITY WILL BE MORE LIKELY. HOWEVER...THE PRESENCE OF SAID
INSTABILITY MAY BE DIMINISHED IF RAIN OCCURS AHEAD OF THE MORE
INTENSE FORCING.
BEYOND THE PASSAGE OF THE SYSTEM THIS EVENING...THE CONVECTIVE
FORECAST BECOMES RATHER DIFFICULT IN TERMS OF SPECIFIC TIMING AND
PLACEMENT. SMEARY MODEL QPF BEHIND THE TUESDAY NIGHT SYSTEM IS
TOUGH TO PLACE WITH REGARDS TO FORCING SIGNALS...ESPECIALLY AS MID
LEVEL RIDGING CONTINUES TO BUILD INTO THE AREA DURING THIS TIME
FRAME. WILL KEEP POPS RATHER LIMITED ON WEDNESDAY...BEFORE GOING
DRY BY WEDNESDAY AFTERNOON IN THE SOUTHWEST AND WEDNESDAY NIGHT
ELSEWHERE. BY THIS POINT...MOST OF THE MODELS ARE DEPICTING
FORCING WELL NORTH OF THE CWA AS THE WARM SECTOR ESTABLISHES
ITSELF OVER THE OHIO VALLEY. ANOTHER WRENCH IN THE SOLUTION
INVOLVES THE POSSIBILITY OF SOME OF THE ACTIVITY OVER MICHIGAN
TURNING SOUTH AND PUNCHING THROUGH THE RIDGE INTO CENTRAL OHIO ON
WEDNESDAY NIGHT. THOUGH IT IS NOT AN IMPOSSIBILITY...IT SEEMS LIKE
AN UNLIKELY SOLUTION...AND A DRY FORECAST WILL BE MAINTAINED.
AFTER A FULL DAY IN THE WARM SECTOR ON THURSDAY...FLATTENING
HEIGHTS WILL ALLOW FOR A RETURN OF PRECIPITATION CHANCES BY
FRIDAY. THIS HAS BEEN SLOWED DOWN SLIGHTLY FOR THIS FORECAST
PACKAGE...FOCUSING MAINLY ON FRIDAY NIGHT.
TEMPERATURES THROUGH THE WEEK WILL BE VERY WARM...POSSIBLY TO NEAR
RECORD VALUES. THE WARMEST DAY OF THE WEEK FOR THE WHOLE AREA
APPEARS TO BE THURSDAY...WITH LITTLE TO NO CHANCE OF
PRECIPITATION...PLENTY OF SUNSHINE...AND SOUTHWESTERLY FLOW IN A
WELL MIXED BOUNDARY LAYER. WITH A SLIGHT SLOW DOWN IN TIMING FOR
THE NEXT WEATHER SYSTEM ON FRIDAY...SIMILAR CONDITIONS ARE NOW
ALSO EXPECTED TO PERSIST FOR THE SOUTHEASTERN FORECAST AREA ON
FRIDAY. ALTHOUGH THIS FORECAST PACKAGE WILL NOT TAKE THE LEAP...A
90 DEGREE READING IN THE FAR SOUTH ON THURSDAY OR FRIDAY SEEMS
LIKE A LEGITIMATE POSSIBILITY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
SHORT WAVE ENERGY WILL BE PUSHING EAST OF THE AREA AT THE START OF
THE PERIOD AND THIS SHOULD LEAD TO A DECREASING CHANCE OF
SHOWERS/THUNDERSTORMS THROUGH WEDNESDAY MORNING. MID LEVEL RIDGING
WILL THEN BUILD INTO THE REGION THROUGH THURSDAY. THIS WILL LEAD TO
RISING HEIGHTS AND 8H TEMPS PUSHING UP INTO THE 16 TO 18 DEGREE
CELSIUS RANGE BY THURSDAY AFTERNOON. AS A RESULT...EXPECT A DECENT
WARM UP THROUGH MID WEEK WITH HIGHS BOTH WEDNESDAY AND THURSDAY WELL
INTO THE 80S.
SOME MODEL DIFFERENCES THEN EXIST WITH HOW FAST/HOW MUCH THE RIDGE
WILL BREAK DOWN THROUGH THE END OF THE WEEK AND AS A RESULT...THE
TIMING AND PLACEMENT OF A COLD FRONT THAT MAY SAG DOWN INTO THE
AREA. THE 30.00Z ECMWF WAS THE SLOWEST WITH THIS AND A QUICK LOOK AT
THE 30.12Z ECMWF LOOKS LIKE IT IS EVEN SLOWER AND STRONGER WITH THE
RIDGE. BASED ON THESE TRENDS...WILL SLOW DOWN THE ONSET OF PCPN
THURSDAY NIGHT INTO FRIDAY. WILL THEN ALLOW FOR THE FRONT TO PUSH
DOWN INTO THE AREA THROUGH THE END OF THE WEEK...BUT BASED ON THE
LATEST ECMWF...NOT SURE HOW FAR IT WILL ACTUALLY GET. WILL THEREFORE
LINGER AT LEAST LOW POPS ALL THE WAY INTO SUNDAY. THE 30.12Z GFS IS
BRINGING CONSIDERABLY COOLER TEMPERATURES BEHIND THE FRONT THIS
WEEKEND BUT AGAIN...THE ECMWF IS TRENDING SLOWER/WARMER. WILL GO
AHEAD AND TAKE A BLEND OF THE TWO WITH MORE OF AN EMPHASIS TOWARD
THE WARMER ECMWF THROUGH EARLY NEXT WEEK.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
IT WILL BE A COMPLEX TAF FORECAST IN THE FIRST PART AND LATTER
PART OF HIS PACKAGE.
SURFACE ANALYSIS DEPICTS TWO BOUNDARIES ACROSS THE REGION THIS
MORNING. ONE...NEARLY ALIGNED EAST-WEST NEAR THE OHIO RIVER...AND
ANOTHER SAGGING SOUTHEAST TOWARD THE KDAY/KCMH/KLCK TAFS. HAVE
DECIDED THAT THE BOUNDARY NEAR THE OHIO RIVER IS MORE OF A FRONTAL
BOUNDARY WHICH DEMARCATES DEEPER MOISTURE TO THE SOUTH VERSUS
NORTH OF IT. THIS BOUNDARY IS FORECAST TO SLOWLY LIFT BACK NE AS A
WARM FRONT THROUGH THE DAY AS ANOTHER EMBEDDED UPPER LEVEL WX
DISTURBANCE TRACKS NE FROM THE SOUTHERN PLAINS TO THE LOWER OHIO
VALLEY.
IN THE NEAR TERM...GIVEN PLENTY OF RAINFALL ACROSS THE
REGION...THE LOW LEVELS ARE QUITE MOIST. OBSERVATIONS AROUND THE
REGION AND LOCAL MODEL GUIDANCE SUGGEST THAT IFR CIGS SHOULD
DEVELOP OVERNIGHT WHICH MAY PREVENT SOME TAFS FROM BEING USED AS
AN ALTERNATE DESTINATION GIVEN LOCAL REGULATIONS. FOR NOW...WILL
BE FORECASTING CIGS BETWEEN 6-9 HUNDRED FEET WITH MVFR VSBYS. LOW
CLOUDS AND MIST SHOULD BURN OFF BY LATE MORNING AND HAVE CHOSEN
15Z AS THE BEST POSSIBLE TIME FOR THIS TO OCCUR.
THEREAFTER...AS MENTIONED...A WARM FRONT WILL LIFT NE THROUGH THE
REGION LATE THIS AFTERNOON AND OVERNIGHT. THIS FEATURE WILL
COMBINE WITH AN UPPER LEVEL DISTURBANCE ALOFT TO PRODUCE SHOWERS
AND THUNDERSTORMS. IT IS TOO EARLY AT THIS POINT TO PINPOINT EXACT
TIMING OF THUNDERSTORMS SO HAVE USED THE VCTS DESCRIPTOR ALONG
WITH PREDOMINATE MVFR VSBYS IN SHOWERS. OF COURSE...WHERE
THUNDERSTORMS OCCUR...LOCAL MVFR CIGS AND LOCAL IFR VSBYS WILL BE
POSSIBLE. PCPN SHOULD DECREASE FROM SW TO NE OVERNIGHT AS THE
DISTURBANCE MOVES OFF TO THE NE AS WELL...ALLOWING SOME SUBSIDENCE
TO TAKE PLACE IN ITS WAKE.
OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY AND SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
200 AM EDT TUE MAY 1 2012
.SYNOPSIS...
LOW PRESSURE IS LOCATED OVER INDIANA WITH A WARM FRONT EAST ACROSS
NORTHERN OHIO TO WESTERN PENNSYLVANIA. A COLD FRONT EXTENDED
SOUTHWEST FROM THE LOW. THE LOW WILL TRACK NORTHEAST ACROSS LAKE
ERIE THIS EVENING...EVENTUALLY DRAGGING THE COLD FRONT ACROSS THE
AREA OVERNIGHT. HIGH PRESSURE WILL BUILD IN FOR TUESDAY MORNING.
TUESDAY EVENING INTO WEDNESDAY...THE FRONT WILL SURGE BACK NORTH
ACROSS THE AREA AS A WARM FRONT.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LOW NOW SE OF THE AREA...AND WITH IT THE THREAT OF SEVERE TSRA. UPDATED
TO REMOVE ALL REMAINING COUNTIES FROM WATCH 211.
INITIAL DISCUSSION...
LOW PRESSURE OVER INDIANA WILL MOVE ENE ACROSS LAKE ERIE THIS
EVENING. A WARM FRONT EAST OF THE LOW CURRENTLY EXTENDS ACROSS
NORTHWEST OHIO AND THE CENTRAL LAKESHORE AND THEN SOUTHEAST
THROUGH NORTHEAST OHIO INTO WESTERN PA. A COLD FRONT WILL FOLLOW
THE LOW MOVING ACROSS THE AREA OVERNIGHT. MAIN CONCERN FOR THIS
EVENING IS THE POTENTIAL FOR SEVERE WEATHER. WITH TEMPS IN THE
LOWER 80S IN THE WARM SECTOR ACROSS THE SOUTHERN TIER OF COUNTIES
AND DEWPOINTS NEAR 60...LI`S ARE NOW -2 TO -3 FROM FDY TO MFD.
EXPECT AIRMASS TO CONTINUE TO DESTABILIZE THROUGH 6 OR 7PM AND
THEN SLOWLY BEGIN TO BECOME MORE STABLE THROUGH THE EVENING.
FORECAST SOUNDINGS SHOW A GOOD MID LEVEL DRY SLOT INDICATING A
POTENTIAL FOR DOWN BURSTS AND AT LAST LOOK DOWNDRAFT CAPE HAD
REACHED 900J/KG. ALSO SURFACE BASED CAPES ARE JUST OVER 1000J/KG
ON RUC JUST TO OUR SOUTH AND WOULD EXPECT THAT AIR WILL BE LIFTED
NORTH INTO THE AREA THROUGH THE EVENING SO HAIL ALSO A POSSIBILITY.
RADAR SHOWS BAND OF RAIN FROM LOWER MI SOUTHWEST THRU NRN INDIANA
AND ILLINOIS WITH THUNDERSTORMS NOW DEVELOPING ON THE LEADING EDGE
OVER WEST CENTRAL INDIANA AND SRN ILLINOIS. EXPECT THESE TO TRACK
NORTHEAST WITH CURRENT MOTION BRINGING THUNDER FROM WESTERN
INDIANA INTO WESTERN CWA COUNTIES BETWEEN 8 AND 9PM. ...ALTHOUGH
DO EXPECT SHOWERS INTO NWRN BEFORE THEN. WILL HAVE CAT POPS FOR
THE ENTIRE AREA WITH THE POSSIBILITY OF SEVERE ACROSS ALL BUT THE
NORTHWEST CORNER. WILL CARRY THIS CHANCE OF SEVERE THROUGH THE
EVENING AND THEN TRANSITION TO SHOWERS OVERNIGHT WITH POPS ENDING
FROM THE NORTHWEST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
NEED TO BE BRIEF. TUESDAY MORNING SHOULD BEGIN DRY WITH HIGH
PRESSURE BUILDING IN FROM THE NORTH. THE COLD FRONT THAT MOVES
THROUGH TONIGHT SHOULD BE AROUND THE OHIO RIVER IN TE PROCESS OF
STALLING. TUESDAY AFTERNOON THE FRONT WILL TURN WARM AND REACH THE
SWRN CWA COUNTIES. DID BRING A CHANCE POP BACK TO THE WESTERN TWO
THIRDS BY EVENING DUE TO THE FRONT. CONTINUED CHANCE POPS TUESDAY
NIGHT GIVE THE FAIRLY MOIST AIRMASS ACROSS THE AREA AND THE FRONT
CONTINUING TO MOVE THROUGH. WEDNESDAY THE AREA WILL REMAIN IN THE
WARM SECTOR. MODELS DO SHOW ENOUGH MOISTURE ACROSS THE AREA FOR
CLOUDS AND THUNDERSTORMS HOWEVER GIVEN THE BUILDING SURFACE HIGH
SHAVED POPS TO LOW TO MID CHANCE. AIRMASS DRIES A BIT WEDNESDAY
NIGHT SO WILL DROP POPS MUCH OF THE AREA. THURSDAY SURFACE HIGH
STILL JUST SOUTHEAST OF THE AREA AND UPPER RIDGING TAKING PLACE AS
WELL. STARTED TO GO COMPLETELY DRY ALTHOUGH A BIT NERVOUS AS CAPES
ARE SHOWN OVER 2000J/KG DURING THE AFTERNOON SO PUT A SLIGHT
CHANCE IN THE GRAPHICS IN CASE CONVECTION BREAKS THROUGH THE CAP.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
BIG PICTURE HAS THE UPPER RIDGE BREAKING DOWN OVER THE COURSE OF THE
WEEKEND. FOR TIMING THIS FAR OUT HAVE TURNED TO THE GFS ENS AND TAKE
A COLD FRONT THROUGH THE AREA SLOWLY FRIDAY NIGHT INTO SATURDAY.
WILL HAVE TEMPS SLIGHTLY COOLER THAN THURSDAY...BUT STILL WARM.
SCATTERED SHOWERS AND THUNDERSTORMS WITH THE FRONT. COOLER FOR THE
SECOND HALF OF THE WEEKEND...RETURNING TO NEAR NORMAL WHEN THE HIGH
REALLY PUSHES DOWN INTO THE AREA.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS RAIN EXITS TO THE EAST THIS EVENING CEILINGS HAVE BRIEFLY DROPPED
TO IFR BUT HAVE NOW GENERALLY RISEN BACK TO MVFR AS A LIGHT
SOUTHERLY WIND DEVELOPS. WEAK AREA OF LOW PRESSURE NEAR LAKE ERIE WILL
SHIFT TO THE EAST OVERNIGHT WITH WINDS VEERING TO MORE WESTERLY/
NORTHWESTERLY. THIS SHOULD RESULT IN CEILINGS DROPPING BACK DOWN
TO IFR BY 8-10Z. CLOUD DEPTH WILL THIN AS WE HEAD INTO TUESDAY
MORNING AND EXPECT TO SCATTER OUT BETWEEN 15-18Z IN MOST LOCATIONS
AS DRIER AIR WORKS INTO NORTHERN OHIO. CHANCES OF SHOWERS AND
THUNDERSTORMS WILL RESUME BY LATE IN THE TAF CYCLE AS THE WARM
FRONT STARTS TO PUSH NORTH AGAIN. CONFIDENCE WAS TOO LOW IN TIMING
TO INCLUDE AT ANY OF THE TERMINALS WITH THIS PACKAGE.
.OUTLOOK...NON-VFR CONDITIONS POSSIBLE WITH SHOWERS AND
THUNDERSTORMS TUESDAY NIGHT INTO WEDNESDAY MORNING...THEN AGAIN
FROM FRIDAY INTO SATURDAY.
&&
.MARINE...
GENERALLY QUIET CONDITIONS EXPECTED ON THE LAKE THROUGH THE NEXT 5
DAYS. NOT EXPECTING WAVES GREATER THAN 2 FEET THROUGH THE PERIOD.
THIS IS ALL DUE TO THE FACT THERE WILL BE NO MAJOR WEATHER SYSTEMS
AFFECTING LAKE ERIE DURING THIS TIME PERIOD. ONLY PROBLEMS TO
CONTEND WITH IS THE THREAT FOR THUNDERSTORMS LATER THIS EVENING.
THERE WILL ALSO BE A CHANCE FOR SHOWERS AND THUNDERSTORMS AT LEAST
THROUGH FRIDAY. ONE THING TO KEEP IN MIND IS THE THREAT FOR SEVERE
THUNDERSTORMS LATER THIS EVENING ON THE LAKE. MARINERS SHOULD KEEP A
CLOSE WATCH TO THE SKY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...DJB/TK
SHORT TERM...TK
LONG TERM...OUDEMAN
AVIATION...KEC
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS PORTLAND OR
840 PM PDT WED MAY 2 2012
.SYNOPSIS...A STRONG PACIFIC FRONTAL SYSTEM IN THE EASTERN PACIFIC
WILL MOVE INLAND TONIGHT AND THURSDAY FOR MORE RAIN...LOCAL BREEZY
CONDITIONS...AND HIGHER CASCADE SNOW. AN UPPER LEVEL TROUGH WILL
CONTINUE SHOWERS FRIDAY AND SATURDAY. HIGH PRESSURE WILL BRING DRIER
AND WARMER WEATHER SUNDAY AND MONDAY.
&&
.UPDATE...RUC LOW LEVEL WINDS (925 TO 850 MB) ARE STILL OUT OF THE
S...WITH A BATCH OF SHOWERS MOVING NORTH IN WEAKER LOW LEVEL
WAA...WHILE THE MAIN PRECIPITATION FIELD ASSOCIATED IMPACTING THE
COAST/COAST RANGE IS MAINLY ASSOCIATED WITH WAA STILL MAINLY LOCATED
AT 750 MB AND ABOVE...THUS THE CEILINGS HOLDING GENERALLY AT 6000 FT
AND HIGHER IN MANY LOCATIONS. WILL INCREASE POPS SLIGHTLY DURING THIS
EVENING PERIOD TO ACCOUNT FOR THIS LIGHTER PRECIP IN THE PRE-MIDNIGHT
HOURS...THOUGH IN THE VALLEY WE EXPECT VERY LIGHT TO NO ACCUMULATIONS
WITH THIS FIRST BATCH...WITH UP TO 0.03 OBSERVED ON THE HIGH END SO
FAR. EXPECT DEEP LAYER SATURATION TO COMMENCE SOON FROM THE SOUTH
AND WEST AS INDICATED BY CEILINGS SHOWING SIGNS OF COMING DOWN AND
INCREASED INTENSITY OF RADAR RETURNS ALONG THE NORTH COAST RANGE
THIS EVENING. EXPECT PRECIPITATION PRETTY MUCH EVERYWHERE OVERNIGHT
AND INTO THE MORNING. PRECIP WILL TAKE THE LONGEST TO COMMENCE NORTH
OF THE COLUMBIA RIVER BEING FURTHER NORTH OF THE FRONTAL BOUNDARY
AND IN OFFSHORE FLOW.
WE GENERALLY EXPECT THE WARM FRONT TO REMAIN ALONG OUR SOUTHERN
CWA...BUT IT MAY LIFT ENOUGH NORTH TO ALLOW STRONGER WINDS SOUTH OF
THE BOUNDARY TO SNEAK INTO THE CENTRAL OREGON COAST FOR A SHORT
TIME...MAINLY IN THE PRE-DAWN HOURS THROUGH JUST AFTER SUNRISE...TO
CREATE SOME BREEZY TO LOCALLY WINDY CONDITIONS. BOTH THE LATEST NAM
AND RUC CONFIRM A SLIGHTLY FURTHER NORTHWARD TRACK TO THE LOW. EXPECT
BREEZY CONDITIONS IN THE SOUTHERN TIER INLAND ZONES AS WELL IN THE
MORNING AS THE SURFACE LOW MOVES INLAND WHILE WEAKENING. NOTE THE
GALE WARNING ISSUED WITH THIS EVENING PACKAGE DISCUSSED BELOW. KMD
.SHORT TERM...PREVIOUS SHORT TERM DISCUSSION UNCHANGED...RADAR
IMAGERY SHOWS A FEW SHOWERS LINGERING OVER THE COAST RANGE AND
CASCADES THIS AFTERNOON AHEAD OF AN APPROACHING SYSTEM. THIS SYSTEM
IS BEING PUSHED ALONG BY A 130-140KT ZONAL JET LOCATED AROUND 40N
AND DEVELOPING A CLOSED LOW NEAR 42N 134W. MODELS ARE IN GOOD
AGREEMENT THAT THIS LOW WILL CONTINUE TO TRACK SOUTHWARD LATE THIS
AFTERNOON TOWARDS SOUTHERN OREGON...AND LIMIT WINDS FOR THE NORTHERN
AND CENTRAL OREGON COAST.
RAIN WILL REACH THE CENTRAL OREGON COAST EARLY THIS EVENING...NEAR
SUNSET...AND SPREAD INLAND AND NORTHWARD OVERNIGHT. THE HEAVIEST RAIN
WILL BE CONCENTRATED IN THE SOUTHERN PORTION OF THE FORECAST AREA
ALONG THE CENTRAL OREGON COAST AND COAST RANGE. SNOW LEVELS HAVE
RISEN ABOVE PASSES THIS AFTERNOON AND MOST OF THE PRECIPITATION
SHOULD FALL AS RAIN. ALTHOUGH THE HIGHER ELEVATIONS OF THE CASCADES
WILL HAVE ACCUMULATING SNOW.
THE RAIN WILL EASE UP LATE THURSDAY AFTERNOON BUT AN APPROACHING
TROUGH UPPER TROUGH WILL CONTINUE SHOWERS THROUGH FRIDAY. COOLER AIR
ALOFT WILL BRING SNOW LEVELS DOWN TO NEAR PASS LEVEL..WITH POSSIBLE
BRIEF SNOW ACCUMULATIONS BELOW THE MOUNTAIN PASSES. THE SHOWERS WILL
BE MORE CONVECTIVE FRIDAY AFTERNOON AS THE TROUGH AXIS SWINGS
INLAND...AND THERE MAY EVEN BE A COUPLE OF LIGHTNING STRIKES.
FORECAST CONFIDENCE IS TOO LOW TO MENTION THUNDERSTORMS IN THE
FORECAST AT THIS TIME.
A WEAK SURFACE TROUGH COMBINED WITH MOIST ONSHORE FLOW WILL CONTINUE
A THREAT FOR SHOWERS ON SATURDAY. HIGH PRESSURE AND OFFSHORE FLOW
WILL BRING AN END TO THE RAIN SATURDAY EVENING.
.LONG TERM...ALL MEDIUM RANGE MODELS SEEM TO POINT AT A RELATIVELY
SIGNIFICANT DRYING TREND BEGINNING OVER THE LATTER HALF OF THE
WEEKEND AND CONTINUING INTO MID WEEK NEXT WEEK. AN UPPER LEVEL RIDGE
WILL SHIFT INLAND OVER THE WESTERN U.S. ON SUNDAY AND MAKES SLOW
PROGRESSION EASTWARD...BRINGING DRY AND MILD CONDITIONS TO THE AREA
SUNDAY THROUGH TUESDAY. MODELS DO SHOW DIFFERENCES IN TIMING WITH
THE FIRST SYSTEM ARRIVING AFTER THE BRIEF DRY PERIOD...SO HAVE
CONTINUED THE DRYING TREND FOR NOW UNTIL DETAILS SOLIDIFY LATER IN
THE FORECAST PERIOD. BROWN
&&
.AVIATION...RAIN WILL CONTINUE TO SPREAD ACROSS THE AREA THIS
EVENING AND OVERNIGHT. MOST LOCATIONS EAST OF THE COAST RANGE WILL
REMAIN VFR OVERNIGHT IN WEAK LOW LEVEL OFFSHORE FLOW. HOWEVER...
HEAVIER RAIN FROM SALEM SOUTH WILL INCREASE THE LIKELIHOOD OF MVFR
CEILINGS AFTER 09Z. MVFR CONDITIONS WILL DEVELOP ALONG THE COAST
OVERNIGHT...ESPECIALLY SOUTH OF TILLAMOOK WHERE RAINFALL RATES
ARE EXPECTED TO BE HIGHER AND SOUTHERLY FLOW IS EXPECTED TO
DEVELOP. CONDITIONS WILL IMPROVE AROUND 16-18Z ALONG THE COAST AND
19-21Z INLAND AS A COLD FRONT SWEEPS ACROSS THE AREA.
KPDX AND APPROACHES...EXPECT RAIN TO INCREASE OVERNIGHT. HOWEVER...
VFR CONDITIONS WILL GENERALLY HOLD IN LOW LEVEL OFFSHORE FLOW.
MVFR CONDITIONS WILL LIKELY DEVELOP AFTER 16Z AND CONTINUE UNTIL
AROUND 20-22Z AS WEAK LOW LEVEL FLOW COMBINES WITH STEADY RAIN. A
COLD FRONT WILL MOVE ACROSS THE AREA AROUND 20Z WITH CONDITIONS
IMPROVING TO VFR.
&&
.MARINE...A SURFACE LOW PRESSURE SYSTEM WILL AFFECT THE CENTRAL
OREGON COAST LATE TONIGHT THROUGH THURSDAY. IT APPEARS THAT THIS
LOW WILL TRACK FURTHER NORTH THAN PREVIOUSLY ANTICIPATED. AS A
RESULT...HAVE ISSUED A GALE WARNING FOR OUR SOUTHERN WATERS FOR
LATE TONIGHT THROUGH EARLY THURSDAY MORNING. WINDS ACROSS THE
NORTHERN WATERS SHOULD REMAIN BELOW SMALL CRAFT CRITERIA.
SEAS CURRENTLY SIT IN THE 6 TO 8 FT RANGE AND WILL LARGELY REMAIN
THERE FOR THE NEXT 24 TO 36 HOURS OR MORE. SOUTHERLY WIND WAVES
WILL INCREASE SIGNIFICANTLY OVERNIGHT BECOMING NEARLY PERPENDICULAR
TO THE SWELL THUS RESULTING IN THE POTENTIAL FOR CONFUSED SEA
STATES...PARTICULARLY CLOSER TO SHORE. THE UPPER LOW CENTER WILL
MOVE INLAND BY MID-DAY THURSDAY SIGNALING A RETURN TO BETTER SWELL
AND WIND WAVE ALIGNMENT FROM THE WEST-NORTHWEST. AFTER THURSDAY...
DONT SEE ANY SIGNIFICANT SWELL THREAT AS HIGH PRESSURE BUILDS
OFFSHORE HEADING IN TO NEXT WEEK.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...GALE WARNING FROM 1 AM TO 10 AM PDT THURSDAY FOR COASTAL WATERS
FROM CASCADE HEAD TO FLORENCE OR OUT 10 NM-WATERS FROM
CASCADE HEAD TO FLORENCE OR FROM 10 TO 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH BAR FROM 1 AM TO 6 AM PDT
THURSDAY FOR COLUMBIA RIVER BAR.
SMALL CRAFT ADVISORY FOR ROUGH BAR FROM 2 PM TO 7 PM PDT
THURSDAY FOR COLUMBIA RIVER BAR.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
147 AM EDT TUE MAY 1 2012
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL STRENGTHEN AND CONTROL THE WEATHER
THROUGH THE WEEK. SMALL AREAS OF UPPER LEVEL ENERGY WILL PROVIDE
SOME SHOWERS AND STORMS OVER THE MOUNTAINS AND MORE ISOLATED
ACTIVITY IN THE FOOTHILLS AND PIEDMONT LATE IN THE DAY. A COLD
FRONT IS EXPECTED TO MOVE FROM NORTH TO SOUTH INTO THE AREA NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1030 PM EDT...THE SPC MESOANALYSIS PAGE IS STILL SHOWING
MUCAPES OF 2000-3000 J/KG OVER A GOOD BIT OF THE FA. SURFACE BASED
PARCELS WILL HAVE TROUBLE LIFTING AS THE CIN IS INCREASING.
HOWEVER...AN INCREASING LLVL JET AND A VERY MOIST AIRMASS IS
RESULTING IN ELEVATED CONVECTION NOW STARTING TO DEVELOP OVER THE
UPSTATE AND NE GA. WITH STEEP LAPSE RATES FROM H7-H5...THESE
ELEVATED UPDRAFTS ARE QUITE VIGOROUS AND WILL LIKELY CONTINUE TO
PRODUCE HAIL. THE SAME PROCESS...ALBEIT WITH THE FORCING COMING FROM
OROGRAPHIC LIFT...HAS TRIGGERED STRONG TO SEVERE STORMS MUCH OF THE
EVENING OVER THE CENTRAL AND NRN MTNS AND WESTERN FOOTHILLS. IT
APPEARS THAT THE LLVL JET WILL TAKE OVER AS THE PRIMARY FORCING
MECHANISM...AND CONVECTIVE CONVERGE SHOULD CONTINUE TO DECREASE
ACROSS THE MTNS. BUT...OUT ACROSS THE FOOTHILLS AND PIEDMONT OF
CAROLINAS AND NE GA THIS PROCESS IS LIKELY TO RESULT IN AN INCREASE
IN COVERAGE OVER THE NEXT COUPLE HOURS. A WEAK H5 SHORT WAVE
ANALYZED BY THE RUC OVER THE SRN APPALACHIANS WILL ALSO HELP THIS
PROCESS ALONG. THIS ISN/T THE PLAINS...AND THE LLVL JET ISN/T THAT
STRONG...SO I THINK BY 0500 UTC MOST OF THE CONVECTION SHOULD START
TO WIND DOWN. STILL...POPS HAVE BEEN RAISED TO LOW END LIKELY ALONG
THE I-85 CORRIDOR OF THE UPSTATE AND EXTREME SRN NC FOR THE NEXT
COUPLE HOURS.
AS OF 805 PM EDT...GRIDS ARE IN GOOD SHAPE. STRONG TO SEVERE STORMS
HAVE REMAINED CONFINED TO THE CENTRAL AND NRN NC MTNS AND THE NW
FOOTHILLS...EXACTLY AS WAS IN THE FORECAST.
PREVIOUS DISCUSSION...
AS OF 200 PM... 12Z NAM...LOCAL WRF AND THE 12Z GFS INDICATE THAT
CONVECTIVE INITIATION WILL OCCUR OVER THE NORTHERN MOUNTAINS IN THE
19Z-21Z TIMEFRAME...WITH CONVECTION THEN MOVING EAST THROUGH THE NC
FOOTHILLS INTO THE NORTHERN PIEDMONT. ADDITIONAL DEVELOPMENT THEN IS
FORECAST ESSENTIALLY THROUGH THE LEE TROUGH AROUND 00Z WITH STORMS
ACROSS THE NORTHERN UPSTATE INTO NE GA. CONVECTIVE ACTIVITY SHOULD
THEN WANE BY 06Z OR SO. CURRENT POP FIELD LOOKS GOOD IN REGARD TO
THIS SCENARIO.
SBCAPES ALREADY HAVE INCREASED INTO THE 1500-2000J/KG RANGE.
HOWEVER...IT LOOKS LIKE THERE IS SUFFICIENT CIN TO CAP CONVECTIVE
INITIATION UNTIL ABOUT 20Z IN THE NORTHERN MOUNTAINS. WITH BULK
SHEAR AROUND 30KT...THIS MY BE ENOUGH TO SUSTAIN UPDRAFTS AND ALLOW
CONVECTION TO SPREAD OUT OVER THE FOOTHILLS. ALSO...DCAPE OVER THE
MOUNTAINS IS AROUND 1000J...SO A FEW SEVERE STORMS ARE POSSIBLE WITH
LARGE HAIL AND DAMAGING WINDS.
ALL INDICATIONS ARE THAT THE STORMS WILL DISSIPATE BY 06Z...SO
IT SHOULD BE QUIET LATE TONIGHT WITH JUST DOME DEBRIS CLOUDINESS AND
PATCHY FOG. SOME STRATUS MAY MAKE A RUN AT THE EASTERN AND SOUTHERN
PERIPHERY OF THE CWA AROUND SUNRISE.
ON TUE...EXPECT A FEW SHOWERS TO BEGIN CROPPING UP IN THE MOUNTAINS
TUE MORNING WITH UPSLOPE FLOW AND AN APPROACHING VORT. SCATTERED
SHOWERS AND STORMS ARE THEN EXPECTED TO DEVELOP ACROSS THE NC
FOOTHILLS/PIEDMONT AS A WEAK FRONTAL BOUNDARY DROPS INTO THE AREA
DURING THE AFTERNOON. A FEW STORMS COULD MOVE OUT INTO NE GA AND THE
SC FOOTHILLS/PIEDMONT LATE IN THE DAY. CONDITIONAL INSTABILITY WILL
ONCE AGAIN BE ON THE ORDER OF 1500J/KG SO CAN`T RULE OUT A FEW
SEVERE STORMS OVER WESTERN NC WHERE WIND SHEAR IS THE GREATEST.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
AS OF 140 PM MONDAY...SHORT RANGE MODELS INDICATE THAT THE CENTER OF
H5 RIDGE WILL BUILD OVER THE SAVANNAH RIVER BASIN WEDNESDAY AND
THURSDAY. SKY COVER WILL REMAIN LIMITED TO PARTLY CLOUDY CONDITIONS
THROUGH THE PERIOD...ESPECIALLY OVER THE MTNS AND ADJACENT
FOOTHILLS. THE RIDGE WILL SUPPLY THE REGION WITH VERY WARM LLVL
THICKNESSES AND H85 TEMPS BETWEEN 16C TO 18C. USING A BLEND OF MOS
GUIDANCE...FORECAST LOW TEMPS ARE FORECAST TO RANGE FROM THE L50S
ACROSS THE MTN VALLEYS TO L60S EAST...OR AROUND 10 DEGREES ABOVE
NORMAL. THIS WILL SET THE STAGE FOR RECORD TO NEAR RECORD HIGH
TEMPERATURES EACH DAY. HERE ARE THE RECORDS FOR WEDNESDAY AND
THURSDAY FOR KGSP...KCLT...AND KAVL:
KGSP
MAY 2ND 90F IN 1959 FORECAST 90F
MAY 3RD 91F IN 1959 FORECAST 90F
KCLT
MAY 2ND 91F IN 1959 FORECAST 88F
MAY 3RD 94F IN 1902 FORECAST 91F
KAVL
MAY 2ND 88F IN 1935 FORECAST 85F
MAY 3RD 85F IN 1965 FORECAST 86F
WEDNESDAY AND THURSDAY...THE ENVIRONMENT WILL CHANGE LITTLE FROM DAY
TO DAY. FORECAST SOUNDINGS FEATURE A WEAK INVERSION AROUND H8 WITH
CIN VALUES RANGING BETWEEN 30 TO 60 J/KG. WIND FIELDS SHOULD RESULT
IN ONLY WEAK SHEAR...ESPECIALLY ON THURSDAY. THE STORM MODE SHOULD
REMAIN AS PULSE STORMS. GIVEN THE LINGERING INVERSION...LACK OF A
TRIGGER...AND SLOW STORM MOTIONS WILL FAVOR SCHC POPS EAST OF THE
MTNS...WITH CHC POPS ACROSS THE RIDGES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 145 PM MONDAY...THE MEDIUM RANGE MODELS HAVE BEEN RATHER
CHANGEABLE. MOST RECENT HPC WORD SAYS BLENDING ECMWF AND GEFS
ENSEMBLES ARE THE BEST WAY TO GO. WHEN COMPARING THE OPERATIONAL
GFS AND ECMWF START THE MEDIUM RANGE IN A MODERATE 500MB RIDGE
THURSDAY NIGHT. BOTH SHOW THURSDAY EVENING CONVECTION FROM THE
VIRGINIAS TO EASTERN NC. THIS TREND DIMINISHES FOR LATE FRIDAY AS
THE RIDGE FLATTENS. GOING INTO THE WEEKEND...THESE TWO MODELS
DIVERGE IN SOLUTIONS. THE RIDGE REBUILDS OVER THE SE ON THE ECMWF
FOR SATURDAY WHILE RIDGE RETROGRADES TO TEXAS ON THE GFS WITH TROF
FORMING OVER EAST. THE LATEST 12Z GFS BRINGS THE COLD FRONT ACROSS
OUR AREA EARLY SUNDAY WHILE THE PREVIOUS RUN WAITED UNTIL LATE
MONDAY. THE MOST RECENT ECMWF HAD A WEAK FRONT CROSSING OUR REGION
MONDAY NIGHT. OF COURSE...WITH THIS BEING A WEEK AWAY WE WILL HAVE
SLIGHT POPS IN FORECAST THROUGH THE GENERAL TIME UNTIL WE CAN NAIL
DOWN A MORE DEFINITE TIME FOR FRONTAL PASSAGE.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AT KCLT...VFR WITH HIGH CLOUDS FOR THE NEXT SEVERAL HOURS...WITH
FAIRLY HIGH TEMP/DEWPT SPREADS. THE GUIDANCE SUGGESTS YET ANOTHER
LOW CLOUD DECK DEVELOPING ACROSS THE MIDLANDS AND PIEDMONT BY
SUNRISE...HOWEVER...SATELLITE IMAGERY AND SFC OBS SHOW MUCH LESS IN
THE WAY OF CLOUD DEVELOPMENT AT THIS HOUR COMPARED TO THE PAST
SEVERAL DAYS. WILL INCLUDE A FEW HOURS OF MVFR CEILING AROUND
DAYBREAK...WITH CLOUDS SCATTERING OUT BY 14Z AT THE LATEST. SHOULD
BE VFR WITH A S TO SW WIND FROM THAT POINT ONWARD. THUNDERSTORM
CHANCES ARE TOO LOW TO INCLUDE AT THIS TIME.
ELSEWHERE...VFR THROUGH ABOUT DAYBREAK. PATCHES OF MID AND HIGH
CLOUDS MAY KEEP FOG FROM GETTING TOO DENSE IN THE MTN VALLEYS...SO
VIS WAS LIMITED TO THE MVFR RANGE AT KAVL STARTING AT 10Z. IF IT
FORMS IT SHOULD NOT CONTINUE BEYOND ABOUT 13Z AS WE WARM UP QUICKLY.
THE OTHER POSSIBLE FOG OR LOW CLOUD SPOT WILL BE KHKY AS LOW LEVEL
MOISTURE IS A BIT HIGHER DUE TO RECENT RAINFALL. THE OTHER TAF SITES
WILL BE KEPT VFR. A BRIEF MVFR CEILING WILL NOT BE RULED OUT IN THE
MIDDLE PART OF THE MORNING AS SOLAR HEATING DEVELOPS A CU FIELD...
BUT BASES SHOULD RISE UP ABOVE 030 BY 16Z AT THE LATEST. EXPECT S TO
SW WIND TO CONTINUE.
OUTLOOK...SCATTERED MAINLY DIURNAL THUNDERSTORMS WILL BE THE MAIN
PROBLEM FOR WEDNESDAY THROUGH FRIDAY. PATCHES OF FOG AND STRATUS ARE
ALSO POSSIBLE EACH MORNING AS WELL. APART FROM THAT...MOST OF THE
TIME CONDITIONS SHOULD BE VFR.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY/PM
SHORT TERM...NED
LONG TERM...DEO
AVIATION...PM
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1137 PM CDT MON APR 30 2012
.AVIATION...
STORMS HAVE EXITED THE AREA THIS EVENING BUT GUSTY WINDS WILL
RETURN TO THE SOUTHEAST OVERNIGHT. CONFIDENCE IS INCREASING IN LOW
STRATUS DEVELOPMENT NEAR KCDS NEAR DAYBREAK AND HAVE NOW INCLUDED
THIS IN A TEMPO. DURING THE AFTERNOON...WINDS WILL BECOME GUSTY
OUT OF THE SOUTH TO SOUTHWEST IN RESPONSE TO A DEEPENING LOW
PRESSURE SYSTEM.
&&
.PREV DISCUSSION... /ISSUED 950 PM CDT MON APR 30 2012/
UPDATE...
HAVE UPDATED THE FORECAST TO REMOVE THUNDER MENTION EXCEPT FOR
EASTERN AREAS AND REMOVED SEVERE TSTORM WATCH EXCEPT FOR THE
ROLLING PLAINS.
PREV DISCUSSION... /ISSUED 226 PM CDT MON APR 30 2012/
SHORT TERM...
WE ARE BASICALLY IN A WAIT AND SEE MODE FOR WHEN/IF SEVERE WEATHER
WILL INITIATE. 19Z RADAR IMAGE SHOWS TWO BOUNDARIES ACROSS THE
AREA...FIRST ONE WAS LOCATED SOUTHWEST OF LUBBOCK WHICH WAS ORIENTED
NORTHWEST TO SOUTHEAST WITH THE SECOND ONE LOCATED OVER THE ROLLING
PLAINS ORIENTED NORTH/SOUTH. LATEST VISIBLE SATELLITE IMAGERY AND
OFFICE TOWER CAMERA ARE SHOWING CU FIELD TRYING TO DEVELOP ALONG
THIS BOUNDARY WHILE SKIES ARE TRYING TO CLEAR IMMEDIATELY
EAST/NORTHEAST OF THE BOUNDARY. THERE IS LITTLE IN THE WAY OF
DYNAMICS TO HELP SHARPEN THE DRYLINE AND PUSH IT EAST SO FEEL THAT
THE WESTERN BOUNDARY SHOULD NOT MOVE TOO MUCH FURTHER EAST.
DEWPOINTS IMMEDIATELY NORTH AND EAST OF THE BOUNDARY HAVE ACTUALLY
BEEN SLOWLY RISING AS EVAPORATION TAKES PLACE FROM THE RAINFALL
YESTERDAY WHICH SHOULD ALSO HELP TO SHARPEN UP THE BOUNDARY A BIT.
19Z RUC RUN KEEPS KLBB CAPPED ALTHOUGH STRENGTH OF THE CAP IS NOT
INSURMOUNTABLE AND THE LATEST HRRR RUNS CONTINUE TO TRY AND BREAK
OUT CONVECTION. THUS...SEVERE WEATHER THREAT STILL LOOKS GOOD WITH
MAIN THREATS LARGE HAIL UP TO BASEBALL SIZE AS WELL AS DAMAGING
WINDS... BUT AN ISOLATED TORNADO STILL REMAINS POSSIBLE.
FORECAST FOR TONIGHT INTO TOMORROW WILL HINGE ON HOW THINGS DEVELOP
THIS AFTERNOON. LOW TEMPS WILL REMAIN A FEW DEGREES ABOVE NORMAL
OVER MOST OF THE AREA AS RICH LOW LEVEL MOISTURE REMAIN IN PLACE
OVER THE REGION. DRYLINE TOMORROW MAY TRY TO PUSH A BIT FURTHER
EAST TOMORROW BUT POOR HANDLE OF THE DRYLINE LAST SEVERAL RUNS IN
THE MODELS MAKE ME A BIT SUSPICIOUS OF WHERE IT MAY BE LOCATED
TOMORROW. IF THE WIND DOES INCREASE OUT OF THE SOUTHWEST...
TEMPERATURES WEST OF THE DRYLINE MAY JUMP INTO THE LOW/MID 90S WHILE
ALONG AND EAST OF THE DRYLINE...TEMPERATURES WILL REMAIN IN THE
80S. ALSO WENT AHEAD AND BUMPED POPS UP INTO THE LOW END OF SLIGHT
CHANCE FOR THE ROLLING PLAINS AS THERE WILL ONCE AGAIN BE QUITE A
BIT OF INSTABILITY EAST OF THE DRYLINE ALTHOUGH CAP STRENGTH MAY
LIMIT THE AMOUNT OF CONVECTION FOR TOMORROW.
JORDAN
LONG TERM...
AN UA LOW ACROSS THE EASTERN PACIFIC IS PROGGED TO NEAR THE BAJA OF
CALIFORNIA LATE TOMORROW NIGHT/EARLY WEDNESDAY MORNING...THUS
PROMOTING THE SHARPENING OF SW FLOW ALOFT. AS SUCH...THE DRYLINE
WILL BE A PROMINENT MESOSCALE FEATURE THROUGHOUT THE EXTENDED
FORECAST. FORECAST MODELS HINT AT QPF ALONG THE DRYLINE /LOCATED OFF
THE CAPROCK/ TOMORROW NIGHT...AS AN IMPULSE IN THE SW FLOW ALOFT
MOVES ACROSS THE SOUTH PLAINS. FORECAST SOLUTIONS DISPLAYED ADEQUATE
CONVERGENCE ALONG THE DRYLINE...PWATS AOA 1.00 INCH AND SFC AND MID
LEVEL INSTABILITY/CAPE OF APPROXIMATELY 1200 J/KG ACROSS THE ROLLING
PLAINS. ALTHOUGH PROGGED MODEL SOUNDINGS EXHIBITED MOISTENED
MID-LEVELS...LOW LEVELS APPEAR RELATIVELY DRY. CURRENT THINKING IS
THAT GUSTY WINDS WILL BE THE PRIMARY THREATS...WITH LITTLE RAINFALL
ACCUMULATION. HOWEVER...HAVE OPTED TO ADD MENTIONABLE POPS ACROSS
THE ROLLING PLAINS NEAREST TO THE BEST MOISTURE AXIS...AS THE
AFOREMENTIONED EMBEDDED DISTURBANCE MAY JUST BE THE SYNOPTIC SPARK
TO INITIATE STORMS. BY THURSDAY THE UA LOW WILL BE TRANSLATING
ACROSS THE BAJA OF CALIFORNIA. ONCE AGAIN THERE ARE HINTS OF CI JUST
SOUTH OF THE CWA ALONG THE DRYLINE...WHICH IS SPATIALLY DISTRIBUTED
ON THE CAPROCK EARLY THURSDAY MORNING. HOWEVER EMBEDDED IMPULSES IN
THE FLOW ALOFT BRUSHING THE FAR SERN ZONES THURSDAY NIGHT COULD
PROMOTE ADDITIONAL CHANCES OF PRECIP ACROSS THE SOUTHERN ROLLING
PLAINS. WILL HOLD OFF ON A PRECIP MENTION ATTM...AS BEST INSTABILITY
APPEARS TO BE SE OF THE FA.
THEREAFTER...UA RIDGING WILL COMMENCE TO MOVE EAST ACROSS THE REGION
FRI-SAT AS LACK OF PRECIP DESPITE A LINGERING DRYLINE SUGGESTS A
DECENT CAPPING INVERSION AT PLAY. WILL HOWEVER NEED TO MONITOR LATER
MODEL RUNS AS TEMPS IN THE 90S MAY BE ENOUGH TO BREAK THE CAP...AND
INITIATE THUNDERSTORM DEVELOPMENT. THE INFLUENCE OF THE UA RIDGE
WILL BE SHORT-LIVED AS IT SHIFTS EAST OF THE SOUTHERN PLAINS BY
SUNDAY...THANKS TO A NW PACIFIC UA LOW DEEPENING ACROSS THE GREAT
BASIN /THIS IS A RADICAL CHANGE FROM THE PREVIOUS RUN/. HINTS OF
CONVECTION OCCURRING NEAR THE STATE LINE ALONG THE DRYLINE
SUNDAY/MONDAY MORNING IS DISPLAYED BY BOTH THE GFS AND ECMWF
SOLUTIONS. WILL HOWEVER MAINTAIN SILENT POPS ATTM SINCE NEXT MONDAY
IS DAY 7 AND AS MENTIONED...A LOT OF THINGS CAN CHANGE.
FIRE WEATHER...
A DRYLINE IS EXPECTED TO SHARPEN ACROSS THE ROLLING PLAINS ON
WEDNESDAY...AND ALLOW DRIER AIR WEST OF THE DRYLINE...TO FILTER
ACROSS PORTIONS OF THE REGION. TEMPS APPROXIMATELY 15 DEGREES ABOVE
NORMAL WILL PROMOTE RELATIVE HUMIDITY VALUES TO FALL BELOW 15
PERCENT...AS 20-FOOT WIND SPEEDS NEAR/SLIGHTLY EXCEED 20 MPH. AS A
RESULT...ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS MAY
OCCUR...AND A MENTION BEYOND THE HAZARDOUS WEATHER OUTLOOK MAY BE
WARRANTED. ONLY MITIGATING FACTOR MAY WHERE AND HOW MUCH EXPECTED
RAINFALL THE AREA WILL RECEIVE TODAY...WHICH COULD PROMOTE GREENUP
AND HIGHER RELATIVE HUMIDITY VALUES THAN ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 55 91 55 88 53 / 10 0 0 0 0
TULIA 60 92 58 90 55 / 10 10 10 10 10
PLAINVIEW 61 93 59 91 57 / 10 10 10 10 10
LEVELLAND 61 92 59 93 58 / 10 10 10 10 10
LUBBOCK 63 92 61 93 60 / 10 10 10 10 10
DENVER CITY 59 94 58 93 58 / 10 10 10 10 10
BROWNFIELD 62 94 59 94 58 / 10 10 10 10 10
CHILDRESS 64 92 64 94 62 / 20 20 20 10 10
SPUR 66 91 62 94 60 / 20 20 20 10 10
ASPERMONT 68 91 64 97 63 / 20 20 20 10 20
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1027 AM PDT Tue May 1 2012
.SYNOPSIS...
A number of weather disturbances will move over the area this
week. The result will be below normal temperatures and occasional
intervals of rain showers in valleys with rain and snow showers
over mountains. Light snow accumulations are possible in the
mountains from time to time. Breezy to locally windy conditions
are also expected at various times for much of the week.
&&
.DISCUSSION...
A weak wave passing through the Central Panhandle Mountains of
Idaho this morning will provide a focus for an organized area of
showers. Snow levels will be near 3500 feet supporting some snow
on Fourth of July and Lookout Passes but given time of year it is
not expected to stick to roadways. Otherwise expect an increase in
showers this afternoon due to a cold pool aloft over the area of
-25 to -27C at 500mb, and afternoon heating which will destabilize
the atmosphere. As 850mb winds back to the southwest in advance of
an approaching wave off the Washington coast, upslope winds will
enhance shower activity over the Northern Mountains. HRRR model
data supports this idea with numerous showers over this area while
scattered light showers develop elsewhere. Exception to this is
the lee of the Cascades where downslope flow will keep the Methow
and Wenatchee River valleys dry as well as the Moses Lake area.
GFS model also continue to argue a minimal threat for
thunderstorms this afternoon near the Canadian border. Given
marginal instability for thunder opted to leave mention out of
forecast. But an isolated lightning strike is not out of the
question today. JW
&&
.AVIATION...
18Z TAFS: A cool and moderately unstable air mass will promote
widespread fields of low VFR or high MVFR cumulus ceilings over
the eastern TAF sites today...with scattered showers developing
during the afternoon and early evening hours. A short wave
disturbance will cross the Cascades this evening and move through
the Columbia Basin overnight. This wave will trigger more
showers...mainly isolated north of Interstate 90...but scattered
south of I-90 which may bring a shower through the KPUW TAF site
after 06Z. During this time of day...showers could be snow or a
mix of rain or snow with mVFR ceilings and visibilities. /MJF
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 54 35 54 37 50 40 / 40 40 40 10 80 50
Coeur d`Alene 51 35 51 36 50 41 / 40 40 60 10 80 70
Pullman 51 34 51 37 51 40 / 20 20 30 10 80 70
Lewiston 59 41 59 41 60 44 / 10 10 10 10 80 70
Colville 59 36 58 36 54 41 / 60 50 50 10 80 70
Sandpoint 49 35 49 34 51 39 / 70 60 60 10 80 80
Kellogg 45 35 46 33 49 38 / 90 50 70 10 80 70
Moses Lake 62 37 62 40 59 41 / 10 10 10 10 60 30
Wenatchee 59 41 60 42 56 44 / 10 10 10 30 60 30
Omak 62 33 62 38 56 40 / 10 30 10 10 80 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
857 AM PDT Tue May 1 2012
.SYNOPSIS...
A number of weather disturbances will move over the area this
week. The result will be below normal temperatures and occasional
intervals of rain showers in valleys with rain and snow showers
over mountains. Light snow accumulations are possible in the
mountains from time to time. Breezy to locally windy conditions
are also expected at various times for much of the week.
&&
.DISCUSSION...
A weak wave passing through the Central Panhandle Mountains of
Idaho this morning will provide a focus for an organized area of
showers. Snow levels will be near 3500 feet supporting some snow
on Fourth of July and Lookout Passes but given time of year it is
not expected to stick to roadways. Otherwise expect an increase in
showers this afternoon due to a cold pool aloft over the area of
-25 to -27C at 500mb, and afternoon heating which will destabilize
the atmosphere. As 850mb winds back to the southwest in advance of
an approaching wave off the Washington coast, upslope winds will
enhance shower activity over the Northern Mountains. HRRR model
data supports this idea with numerous showers over this area while
scattered light showers develop elsewhere. Exception to this is
the lee of the Cascades where downslope flow will keep the Methow
and Wenatchee River valleys dry as well as the Moses Lake area.
GFS model also continue to argue a minimal threat for
thunderstorms this afternoon near the Canadian border. Given
marginal instability for thunder opted to leave mention out of
forecast. But an isolated lightning strike is not out of the
question today. JW
&&
.AVIATION...
12Z TAFS: Cool and somewhat unstable air-mass along with having
the jet stream in close proximity to aviation sites today into
tomorrow will result in showers at times, regardless of time
of day, and some gusty winds. Overall VFR conditions should
prevail at aviation sites into 12Z Wednesday. /Pelatti
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 54 35 54 37 50 40 / 40 40 40 10 80 50
Coeur d`Alene 51 35 51 36 50 41 / 40 40 60 10 80 70
Pullman 51 34 51 37 51 40 / 20 20 30 10 80 70
Lewiston 59 41 59 41 60 44 / 10 10 10 10 80 70
Colville 59 36 58 36 54 41 / 60 50 50 10 80 70
Sandpoint 49 35 49 34 51 39 / 70 60 60 10 80 80
Kellogg 45 35 46 33 49 38 / 90 50 70 10 80 70
Moses Lake 62 37 62 40 59 41 / 10 10 10 10 60 30
Wenatchee 59 41 60 42 56 44 / 10 10 10 30 60 30
Omak 62 33 62 38 56 40 / 10 30 10 10 80 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
934 PM CDT WED MAY 2 2012
.UPDATE...MADE SOME MINOR ADJUSTMENTS TO PCPN TRENDS AND ADDED A
MENTION OF HEAVY RAINFALL TO PARTS OF C/NE/EC WI OVERNIGHT.
A SMALL CLUSTER OF SVR TSTMS WITH LARGE HAIL HAVE PERSISTED FOR
SEVERAL HOURS OVER SOUTHERN MN...AND ARE NOW MOVG EAST INTO WC WI.
THESE ARE DEVELOPING JUST NORTH OF A WARM FRONT...WHICH EXTENDS
EASTWARD INTO CENTRAL WI. SHOWERS ARE INCREASING RAPIDLY OVER
SOUTHERN WI AND HEADING TOWARD C/EC WI...IN RESPONSE TO MOISTURE
CONVERGENCE AND INCREASING MUCAPE ON THE NOSE OF 30-40 KT LLJ.
OTHER CONVECTION WAS OCCURRING OVER THE EASTERN DAKOTAS...IN
RESPONSE TO A S/W TROF AND THE RRQ OF A STG UPPER LEVEL JET.
THE BIG QUESTION IS HOW ALL OF THIS WILL COME TOGETHER OVERNIGHT.
THE 23Z HRRR SEEMED TO HAVE A PRETTY GOOD HANDLE ON ALL THREE OF
THESE AREAS OF PCPN. THE HRRR GENERALLY WEAKENS THE CURRENT
CLUSTER OF STORMS IN WC WI AS IT MOVES TOWARD C WI. THIS MAY
HAPPEN AS THE DEVELOPING CONVECTION IN SOUTHERN WI TAKES OFF AND
CUTS OFF THE MOISTURE INFLOW. EVEN SO...THERE COULD BE A BRIEF
WINDOW OF OPPORTUNITY FOR LARGE HAIL IN C WI BETWEEN 04Z-06Z.
MODELS GENERALLY AGREE THAT A LARGE AREA OF SHOWERS AND TSTMS
WILL DEVELOP OVER C/EC/FAR NE WI DURING THE OVERNIGHT PERIOD...
WITH A THREAT OF HEAVY RAINFALL AS H8 DEW POINTS INCREASE TO
+10 TO +12 C AND PW SURGES TO NEAR 1.5 INCHES. THE CONVECTION
OVER THE NORTHERN PLAINS MAY BRUSH OUR FAR NORTHWEST COUNTIES
LATE TONIGHT.
KIECKBUSCH
&&
.PREV DISCUSSION...ISSUED AT 655 PM CDT WED MAY 2 2012...
SHORT TERM...TONIGHT AND THURSDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW
PRESSURE SITUATED OVER WESTERN KANSAS EARLY THIS AFTERNOON...AND A
COLD FRONT EXTENDING NORTHEAST INTO THE NORTHERN MISSISSIPPI
VALLEY. AN OUTFLOW BOUNDARY FROM THIS MORNINGS CONVECTION HAS
REACHED INTO NORTHERN MISSOURI AND CENTRAL ILLINOIS...THOUGH
CONVECTION HAS YET TO RE-DEVELOP. CLOUD COVER HAS BEEN BUILDING
ACROSS IOWA THIS AFTERNOON WHERE THETAE ADVECTION IS ONGOING...BUT
NO SIGN OF PRECIP HERE EITHER. MEANWHILE...MIXING INTO DRY AIR
ALOFT HAS DISSIPATED THIS MORNINGS CLOUD COVER INTO SCATTERED CU
OVER MUCH OF THE FORECAST AREA. AS A LOW LEVEL JET DEVELOPS AHEAD
THE LOW PRESSURE AND CONVECTION DEVELOPS UPSTREAM...SEVERE WEATHER
CHANCES AND PRECIP AMOUNTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...PLENTY OF UNCERTAINTY WITH THE DETAILS CONCERNING
POTENTIAL CONVECTION. SHORTWAVE TROUGH OVER MONTANA WILL LIFT NE
OVER NORTH DAKOTA AND INTO SOUTH-CENTRAL CANADA. SW FLOW ALOFT WILL
KEEP LOW PRESSURE OVER THE CENTRAL PLAINS WHILE THE COLD FRONT BECOMES
MORE PERPENDICULAR TO THE LOW LEVEL FLOW OVER IOWA AND INTO
WISCONSIN. AHEAD OF THE SURFACE LOW...A SOUTH TO SOUTHWEST LLJ WILL
DEVELOP LATE THIS AFTERNOON INTO THIS EVENING POINTING INTO IOWA AND
NORTHERN ILLINOIS. GOOD MASS CONVERGENCE ON THE NOSE OF THIS LLJ IN
AN AREA OF MU CAPE 1500-2000 J/KG AND MID-LEVEL LAPSE RATES OF 7 TO
7.5 C/KM SHOULD BE SUFFICIENT TO TRIGGER ELEVATED CONVECTION.
FORWARD PROPAGATING CORFIDI VECTORS WOULD TRACK SUBSEQUENT MCS
ENE...THOUGH AM EXPECTING THE STRONGEST THUNDERSTORMS TO FOLLOW THE
GREATEST INSTABILITY OVER THE SOUTHERN 1/3RD OF THE BADGER STATE AND
NORTHERN ILLINOIS. THE 12Z GFS DOES TRY TO RAM THE LLJ INTO EAST-CENTRAL
WISCONSIN ALONG WITH AMPLE INSTABILITY...BUT THINK THIS IS TOO
AMBITIOUS GIVEN THE WSW FLOW ALOFT AND WITHOUT MUCH MID-LEVEL HEIGHT
RISES. THE FLOW DOES TURN A BIT MORE SW OVERNIGHT AS THE RIGHT REAR
QUAD OF A JET STREAK SHIFTS INTO NORTHERN WISCONSIN...SO AM
EXPECTING TO SEE A MORE NORTHWARD PUSH OF THE NOCTURNAL CONVECTION
ACROSS THE FORECAST AREA AFTER MIDNIGHT. WITH THE ELEVATED
INSTABILITY AXIS REMAINING TO OUR SOUTH...HAVE A HARD TIME GETTING
EXCITED ABOUT SEVERE CHANCES...THOUGH ALWAYS TOUGH TO RULE OUT A
MARGINAL SEVERE STORM ADVECTING INTO THE SOUTHERN FORECAST AREA.
WILL KEEP A MENTION OF SEVERE POSSIBILITIES FOR CENTRAL AND
EAST-CENTRAL WISCONSIN...MAINLY FOR LARGE HAIL...AND STRONG WINDS TO
A LESSER EXTENT. CENTRAL AND EAST-CENTRAL WISCONSIN WILL LIKELY SEE
SUBSTANTIAL RAINFALL...WITH SOME GUIDANCE POINTING TOWARDS WELL OVER
AN INCH OF RAIN. WILL TRY TO CAP IT AROUND THERE...SINCE THE
GREATER INSTABILITY IS SOUTH OF THE FORECAST AREA.
THURSDAY...MORNING CONVECTION MAY VERY WELL BE ONGOING AT THE START
OF THE PERIOD...AS THE RIGHT REAR QUAD OF THE JET STREAK WILL BE
OVERHEAD WHILE 850MB CONVERGENCE WILL BE DRAPED OVER CENTRAL
WISCONSIN. THINK THE MORNING MAY TURN OUT TO BE WETTER THAN MODELS
INDICATE AND WILL KEEP THE NEAR CATEGORICAL POPS IN THE FORECAST.
INSTABILITY WILL BE THE QUESTION MARK FOR THE AFTERNOON...AS THE
WARM FRONT WILL REMAIN STALLED ACROSS THE AREA. THE RIGHT REAR QUAD
OF THE JET STREAK WILL PULL OUT BY THE AFTERNOON...BUT WILL DAYTIME
HEATING LEAD TO CLEARING...DESPITE AMPLE MOISTURE THROUGH THE
COLUMN? THINK ANY BREAKS WILL JUST LEAD TO CU BUILD-UP...RESULTING
IN A MOSTLY CLOUDY DAY REGARDLESS. STILL SOME CAPE TO BE HAD...SO
CANNOT RULE OUT SCATTERED COVERAGE OF SHOWERS AND STORMS THROUGH THE
AFTERNOON. WILL MAKE ONLY COSMETIC CHANGES TO POPS. HIGHS IN THE
LOW TO MID 70S.
LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. PCPN CHANCES
WILL BE THE PRIMARY FORECAST ISSUE DURING THIS PERIOD. BUSY WSW
FLOW TO CONTINUE INTO FRIDAY BEFORE MEDIUM RANGE MODELS IN
AGREEMENT WITH BRIEFLY BUILDING AN UPPER RIDGE OVER THE WESTERN
GREAT LAKES REGION SATURDAY INTO SUNDAY. THIS UPPER RIDGE BEGINS
TO FLATTEN LATE IN THE WEEKEND WITH A RETURN TO A SOUTH TO
SOUTHWEST FLOW AHEAD OF A SHORT WAVE TROUGH. MEANWHILE THE
SURFACE BOUNDARY WITH BEST INSTABILITY DROPS WELL SOUTH OF THE
FORECAST AREA LATER FRIDAY INTO FRIDAY NIGHT WITH AN EAST TO
NORTHEAST FLOW AROUND A SURFACE HIGH OVER SOUTHERN CANADA.
WOULD NORMALLY BE AGGRESSIVE WITH ENDING POPS IN THIS
SCENARIO...BUT MDM RANGE MODELS ARE CONSISTENTLY LINGERING A WEAK
H8 BOUNDARY OVER WISCONSIN FOR A POSSIBLE FOCUS OF CONVECTION FOR
AT LEAST A CHANCE OF SHOWERS. THIS H8 BOUNDARY WITH WARMER H8 TEMPS WERE
PRODUCING TOTAL TOTAL VALUES IN THE LOWER 50S...ESPECIALLY TOWARD
WESTERN WISCONSIN. IN ADDITION...BEST UPPER JET DYNAMICS LINGER
ACROSS THE NORTHERN GREAT LAKES REGION TO PROVIDE AREAS OF LIFT.
FOR THE NEW WORK WEEK...A PROGGED DEEPENING UPPER TROUGH WITH
FRONTAL SYSTEM WILL PROVIDE MORE EVEN PCPN CHANCES OF PCPN
THROUGH AT LEAST WEDNESDAY BEFORE A HIGH PRESSURE RIDGE TRIES TO
BUILD IN FROM THE NORTHERN PLAINS AND CANADA. BY MID WEEK NEXT
WEEK PCPN CHANCES MAY BE PRIMARILY DIURNAL VARIETY AS THE UPPER
TROUGH SLOWLY DRIFTS OVER.
HYDROLOGY...RAINFALL AMOUNTS OVER CENTRAL AND EAST CENTRAL
WISCOMSIN FROM LAST NIGHS CONVECTION RANGED FROM 0.40 TO 0.80
INCHES. MORE RAIN IS ANTICIPATED TONIGHT INTO THRUSDAY MORNING AS
A WARM FRONT LIFTS INTO SOUTHERN AND CENTRAL WISCONSIN. PWATS
APPROACH 1.50 BY THURSDAY MORNING. AT THIS TIME BETWEEN 1 TO 1.50
INCHES AREAS RAIN IS EXPECTED FROM TONIGHT THROUGH NOON THURSDAY.
DO NOT EXPECT FLOODING AT THESE NUMBERS...BUT IF STORMS BECOME
MORE WIDESPREAD AND CAN TRAIN ALONG THE WARM FRONT...LOCALLY
HIGHER AMOUNTS POSSIBLE. MAIN STEM RIVERS ARE FAIRLY LOW SO
RUNOFF IS NOT EXPECTED TO IMPACT RIVERS...HOWEVER SMALL STREAMS
MAY BEGIN TO BECOME SWOLLEN IF THE HIGHER AMOUNTS VERIFY.
&&
.AVIATION...VFR CONDITIONS PREVAILED OVER C/NE WI EARLY THIS EVG.
STRATOCUMULUS CLOUDS WERE LIFTING INTO SE MN/SW WI...AND SHOULD
IMPACT THE FORECAST AREA LATE THIS EVG. MVFR CIGS ARE POSSIBLE
ONCE THESE CLOUDS ARRIVE. TSTMS WERE DEVELOPING IN SOUTHERN MN...
NORTH OF A WARM FRONT. A SIMILAR SETUP WILL OCCUR OVER C/NE WI
LATE THIS EVG AND OVERNIGHT...AS S-SW WINDS LIFT A MOIST AND
UNSTABLE AIR MASS OVER A WARM FRONTAL BOUNDARY. THIS SHOULD
RESULT IN TSTMS AND IFR CONDITIONS FOR ALL OF THE TAF SITES.
LOCAL STRONG TO SEVERE TSTMS ARE POSSIBLE IN PARTS OF C/EC
WI...BUT THE MAIN THREAT SHOULD BE HEAVY RAINFALL. RIGHT NOW...
THE HEAVIEST RAINFALL IS EXPECTED NEAR THE ATW/GRB TAF SITES.
THE SHOWERS AND TSTMS ARE EXPECTED TO TAPER OFF LATE TONIGHT
INTO THURSDAY MORNING...WITH SLOWLY RISING CIGS AND IMPROVING
VSBYS THEREAFTER. HOWEVER...SCT TSTMS SHOULD REDEVELOP AS A COLD
FRONT SAGS SE ACROSS THE FORECAST AREA THURSDAY AFTERNOON.
KIECKBUSCH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
655 PM CDT WED MAY 2 2012
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND THURSDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW
PRESSURE SITUATED OVER WESTERN KANSAS EARLY THIS AFTERNOON...AND A
COLD FRONT EXTENDING NORTHEAST INTO THE NORTHERN MISSISSIPPI
VALLEY. AN OUTFLOW BOUNDARY FROM THIS MORNINGS CONVECTION HAS
REACHED INTO NORTHERN MISSOURI AND CENTRAL ILLINOIS...THOUGH
CONVECTION HAS YET TO RE-DEVELOP. CLOUD COVER HAS BEEN BUILDING
ACROSS IOWA THIS AFTERNOON WHERE THETAE ADVECTION IS ONGOING...BUT
NO SIGN OF PRECIP HERE EITHER. MEANWHILE...MIXING INTO DRY AIR
ALOFT HAS DISSIPATED THIS MORNINGS CLOUD COVER INTO SCATTERED CU
OVER MUCH OF THE FORECAST AREA. AS A LOW LEVEL JET DEVELOPS AHEAD
THE LOW PRESSURE AND CONVECTION DEVELOPS UPSTREAM...SEVERE WEATHER
CHANCES AND PRECIP AMOUNTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...PLENTY OF UNCERTAINTY WITH THE DETAILS CONCERNING
POTENTIAL CONVECTION. SHORTWAVE TROUGH OVER MONTANA WILL LIFT NE
OVER NORTH DAKOTA AND INTO SOUTH-CENTRAL CANADA. SW FLOW ALOFT WILL
KEEP LOW PRESSURE OVER THE CENTRAL PLAINS WHILE THE COLD FRONT BECOMES
MORE PERPENDICULAR TO THE LOW LEVEL FLOW OVER IOWA AND INTO
WISCONSIN. AHEAD OF THE SURFACE LOW...A SOUTH TO SOUTHWEST LLJ WILL
DEVELOP LATE THIS AFTERNOON INTO THIS EVENING POINTING INTO IOWA AND
NORTHERN ILLINOIS. GOOD MASS CONVERGENCE ON THE NOSE OF THIS LLJ IN
AN AREA OF MU CAPE 1500-2000 J/KG AND MID-LEVEL LAPSE RATES OF 7 TO
7.5 C/KM SHOULD BE SUFFICIENT TO TRIGGER ELEVATED CONVECTION.
FORWARD PROPAGATING CORFIDI VECTORS WOULD TRACK SUBSEQUENT MCS
ENE...THOUGH AM EXPECTING THE STRONGEST THUNDERSTORMS TO FOLLOW THE
GREATEST INSTABILITY OVER THE SOUTHERN 1/3RD OF THE BADGER STATE AND
NORTHERN ILLINOIS. THE 12Z GFS DOES TRY TO RAM THE LLJ INTO EAST-CENTRAL
WISCONSIN ALONG WITH AMPLE INSTABILITY...BUT THINK THIS IS TOO
AMBITIOUS GIVEN THE WSW FLOW ALOFT AND WITHOUT MUCH MID-LEVEL HEIGHT
RISES. THE FLOW DOES TURN A BIT MORE SW OVERNIGHT AS THE RIGHT REAR
QUAD OF A JET STREAK SHIFTS INTO NORTHERN WISCONSIN...SO AM
EXPECTING TO SEE A MORE NORTHWARD PUSH OF THE NOCTURNAL CONVECTION
ACROSS THE FORECAST AREA AFTER MIDNIGHT. WITH THE ELEVATED
INSTABILITY AXIS REMAINING TO OUR SOUTH...HAVE A HARD TIME GETTING
EXCITED ABOUT SEVERE CHANCES...THOUGH ALWAYS TOUGH TO RULE OUT A
MARGINAL SEVERE STORM ADVECTING INTO THE SOUTHERN FORECAST AREA.
WILL KEEP A MENTION OF SEVERE POSSIBILITIES FOR CENTRAL AND
EAST-CENTRAL WISCONSIN...MAINLY FOR LARGE HAIL...AND STRONG WINDS TO
A LESSER EXTENT. CENTRAL AND EAST-CENTRAL WISCONSIN WILL LIKELY SEE
SUBSTANTIAL RAINFALL...WITH SOME GUIDANCE POINTING TOWARDS WELL OVER
AN INCH OF RAIN. WILL TRY TO CAP IT AROUND THERE...SINCE THE
GREATER INSTABILITY IS SOUTH OF THE FORECAST AREA.
THURSDAY...MORNING CONVECTION MAY VERY WELL BE ONGOING AT THE START
OF THE PERIOD...AS THE RIGHT REAR QUAD OF THE JET STREAK WILL BE
OVERHEAD WHILE 850MB CONVERGENCE WILL BE DRAPED OVER CENTRAL
WISCONSIN. THINK THE MORNING MAY TURN OUT TO BE WETTER THAN MODELS
INDICATE AND WILL KEEP THE NEAR CATEGORICAL POPS IN THE FORECAST.
INSTABILITY WILL BE THE QUESTION MARK FOR THE AFTERNOON...AS THE
WARM FRONT WILL REMAIN STALLED ACROSS THE AREA. THE RIGHT REAR QUAD
OF THE JET STREAK WILL PULL OUT BY THE AFTERNOON...BUT WILL DAYTIME
HEATING LEAD TO CLEARING...DESPITE AMPLE MOISTURE THROUGH THE
COLUMN? THINK ANY BREAKS WILL JUST LEAD TO CU BUILD-UP...RESULTING
IN A MOSTLY CLOUDY DAY REGARDLESS. STILL SOME CAPE TO BE HAD...SO
CANNOT RULE OUT SCATTERED COVERAGE OF SHOWERS AND STORMS THROUGH THE
AFTERNOON. WILL MAKE ONLY COSMETIC CHANGES TO POPS. HIGHS IN THE
LOW TO MID 70S.
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. PCPN CHANCES
WILL BE THE PRIMARY FORECAST ISSUE DURING THIS PERIOD. BUSY WSW
FLOW TO CONTINUE INTO FRIDAY BEFORE MEDIUM RANGE MODELS IN
AGREEMENT WITH BRIEFLY BUILDING AN UPPER RIDGE OVER THE WESTERN
GREAT LAKES REGION SATURDAY INTO SUNDAY. THIS UPPER RIDGE BEGINS
TO FLATTEN LATE IN THE WEEKEND WITH A RETURN TO A SOUTH TO
SOUTHWEST FLOW AHEAD OF A SHORT WAVE TROUGH. MEANWHILE THE
SURFACE BOUNDARY WITH BEST INSTABILITY DROPS WELL SOUTH OF THE
FORECAST AREA LATER FRIDAY INTO FRIDAY NIGHT WITH AN EAST TO
NORTHEAST FLOW AROUND A SURFACE HIGH OVER SOUTHERN CANADA.
WOULD NORMALLY BE AGGRESSIVE WITH ENDING POPS IN THIS
SCENARIO...BUT MDM RANGE MODELS ARE CONSISTENTLY LINGERING A WEAK
H8 BOUNDARY OVER WISCONSIN FOR A POSSIBLE FOCUS OF CONVECTION FOR
AT LEAST A CHANCE OF SHOWERS. THIS H8 BOUNDARY WITH WARMER H8 TEMPS WERE
PRODUCING TOTAL TOTAL VALUES IN THE LOWER 50S...ESPECIALLY TOWARD
WESTERN WISCONSIN. IN ADDITION...BEST UPPER JET DYNAMICS LINGER
ACROSS THE NORTHERN GREAT LAKES REGION TO PROVIDE AREAS OF LIFT.
FOR THE NEW WORK WEEK...A PROGGED DEEPENING UPPER TROUGH WITH
FRONTAL SYSTEM WILL PROVIDE MORE EVEN PCPN CHANCES OF PCPN
THROUGH AT LEAST WEDNESDAY BEFORE A HIGH PRESSURE RIDGE TRIES TO
BUILD IN FROM THE NORTHERN PLAINS AND CANADA. BY MID WEEK NEXT
WEEK PCPN CHANCES MAY BE PRIMARILY DIURNAL VARIETY AS THE UPPER
TROUGH SLOWLY DRIFTS OVER.
&&
.AVIATION...VFR CONDITIONS PREVAILED OVER C/NE WI EARLY THIS EVG.
STRATOCUMULUS CLOUDS WERE LIFTING INTO SE MN/SW WI...AND SHOULD
IMPACT THE FORECAST AREA LATE THIS EVG. MVFR CIGS ARE POSSIBLE
ONCE THESE CLOUDS ARRIVE. TSTMS WERE DEVELOPING IN SOUTHERN MN...
NORTH OF A WARM FRONT. A SIMILAR SETUP WILL OCCUR OVER C/NE WI
LATE THIS EVG AND OVERNIGHT...AS S-SW WINDS LIFT A MOIST AND
UNSTABLE AIR MASS OVER A WARM FRONTAL BOUNDARY. THIS SHOULD
RESULT IN TSTMS AND IFR CONDITIONS FOR ALL OF THE TAF SITES.
LOCAL STRONG TO SEVERE TSTMS ARE POSSIBLE IN PARTS OF C/EC
WI...BUT THE MAIN THREAT SHOULD BE HEAVY RAINFALL. RIGHT NOW...
THE HEAVIEST RAINFALL IS EXPECTED NEAR THE ATW/GRB TAF SITES.
THE SHOWERS AND TSTMS ARE EXPECTED TO TAPER OFF LATE TONIGHT
INTO THURSDAY MORNING...WITH SLOWLY RISING CIGS AND IMPROVING
VSBYS THEREAFTER. HOWEVER...SCT TSTMS SHOULD REDEVELOP AS A COLD
FRONT SAGS SE ACROSS THE FORECAST AREA THURSDAY AFTERNOON.
KIECKBUSCH
&&
.HYDROLOGY...RAINFALL AMOUNTS OVER CENTRAL AND EAST CENTRAL
WISCOMSIN FROM LAST NIGHS CONVECTION RANGED FROM 0.40 TO 0.80
INCHES. MORE RAIN IS ANTICIPATED TONIGHT INTO THRUSDAY MORNING AS
A WARM FRONT LIFTS INTO SOUTHERN AND CENTRAL WISCONSIN. PWATS
APPROACH 1.50 BY THURSDAY MORNING. AT THIS TIME BETWEEN 1 TO 1.50
INCHES AREAS RAIN IS EXPECTED FROM TONIGHT THROUGH NOON THURSDAY.
DO NOT EXPECT FLOODING AT THESE NUMBERS...BUT IF STORMS BECOME
MORE WIDESPREAD AND CAN TRAIN ALONG THE WARM FRONT...LOCALLY
HIGHER AMOUNTS POSSIBLE. MAIN STEM RIVERS ARE FAIRLY LOW SO
RUNOFF IS NOT EXPECTED TO IMPACT RIVERS...HOWEVER SMALL STREAMS
MAY BEGIN TO BECOME SWOLLEN IF THE HIGHER AMOUNTS VERIFY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1204 PM MDT TUE MAY 1 2012
.AVIATION...18Z TAFS. THROUGH 02Z...ISOLATED TO SCATTERED SHOWERS
ALONG WITH ISOLATED THUNDERSTORMS PRODUCING LOCALIZED MVFR...
OTHERWISE VFR. SHOWERS DECREASING IN COVERAGE AFTER 02Z. INCREASING
MIDDLE AND HIGH CLOUDS AFTER 06Z WITH ISOLATED TO SCATTERED
SHOWERS DEVELOPING WEST OF A DOUGLAS TO LARAMIE LINE PRODUCING
LOCALIZED MVFR AND MOUNTAIN OBSCUREMENT...VFR ELSEWHERE. SHOWERS
SPREADING SLOWLY EAST AFTER 12Z...WEST OF AN ALLIANCE TO LARAMIE
LINE. RUBIN
&&
.PREV DISCUSSION... /ISSUED 1051 AM MDT TUE MAY 1 2012/
DISCUSSION...
SHOWERS...GENERALLY SPRINKLES...CONTINUE THIS AT MID MORNING OVER
THE PANHANDLE AS WELL AS UNDER THE BAROCLINIC CLOUD BAND FROM CARBON
TO CONVERSE COUNTIES. A SHORTWAVE AT MID MORNING EXTENDED FROM
NORTHEAST TO SOUTH CENTRAL WYOMING...WITH THE CLOUDS AND SHOWERS
AHEAD OF THE FEATURE. MODELS MOVE THE SHORTWAVE TROUGH EAST AND
THROUGH THE ENTIRE CWA THIS EVENING. AN ASSOCIATED SURFACE COLD
FRONT WAS THROUGH ALL BUT THE SOUTHERN PANHANDLE AT 16Z. WEST TO
NORTHWEST WINDS BEHIND THE FRONT WILL GUST AS HIGH AS 45 MPH.
BUMPED UP POPS SLIGHTLY FOR THE REST OF THE DAY AND OTHERWISE MADE
ONLY MINOR CHANGES TO THE FIRST PERIOD OF THE FORECAST IN A RECENT
UPDATE.
AVIATION...12Z TAFS...
VFR CONDITIONS FOR MOST LOCATIONS...THE EXCEPTION BEING KRWL.
LATEST HRRR GUIDANCE CONTINUES TO FORECAST MVFR CONDITIONS OUT
THAT WAY AS A COLD FRONT APPROACHES. LOOK FOR LOWERING CONDITIONS
AROUND THE 15Z TIME FRAME. WILL CONTINUE TO MONITOR FOR ANY LOWER
CONDITIONS. EXPECT AFTERNOON CONVECTION ACROSS SOUTHEAST WYOMING.
HARD TO PINPOINT EXACT TIMING AND LOCATION...SO WILL CONTINUE VCTS
WORDING IN TAFS.
PREV DISCUSSION... /ISSUED 214 AM MDT TUE MAY 1 2012/
SHORT TERM...TODAY THROUGH THURSDAY...
A GENERALLY WEST-SOUTHWESTERLY FLOW ALOFT WILL REMAIN OVER THE CWA
THIS PERIOD WITH A FEW WEAK IMPULSES EMBEDDED IN THIS FLOW PASSING
ACROSS OVER THE NEXT FEW DAYS. ONE IMPULSE WILL PASS ACROSS THIS
AFTERNOON AND EVENING AND SHOULD BRING SOME SHOWERS AND MAYBE A
COUPLE WEAK STORMS TO MAINLY THE MOUNTAINS...WITH A FEW STRAYING
OVER THE HIGH PLAINS. A BETTER CHANCE FOR ACTIVITY ON WEDS AS A
JET STREAK SHOULD RIDE ACROSS AHEAD OF A MORE SIGNIFICANT
SHORTWAVE THAT WILL MOVE ACROSS IDAHO INTO MONTANA AND NRN
WYOMING. INSTABILITIES REMAINING RATHER LOW SO EXPECT MAINLY
SHOWERS ALONG WITH ISOLATED STORMS. CLEARING OUT FOR A TIME WEDS
NIGHT INTO THURSDAY THEN SHOULD SEE SOME MORE ACTIVITY DEVELOP
INITIALLY OVER THE MOUNTAINS AS WEAK SFC BOUNDARY PUSHES AGAINST
THE MTNS AND ENHANCES UPSLOPE FLOW...WITH SCTD SHOWERS AND TSTRMS
SPREADING OVER THE PLAINS BY LATE IN THE DAY.
ONLY OTHER THING TO MENTION WILL BE SOME GUSTY WINDS AROUND THE
MTNS TODAY AS DECENT MID-LEVEL FLOW MIXES DOWN. SOME GUSTS AROUND
50 MPH POSSIBLE IN WIND-FAVORED AREAS.
LONG TERM...THURSDAY NIGHT THROUGH MONDAY...
LOOKS LIKE A FAIRLY WET EXTENDED PERIOD UPCOMING. FRIDAY LOOKS TO
BE DRY WITH A SLOW MOVING TROUGH OVER THE WEST COAST. BY SATURDAY
AFTERNOON THE GFS IS SHOWING A BACKDOOR FRONT LYING UP AGAINST THE
LARAMIE RANGE WITH MOIST LOW LEVEL SOUTHEASTERLY FLOW INTO THE
PANHANDLE. THIS SET UP SHOULD GIVE US INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS AS UPPER SHORTWAVES INTERACT WITH THE
FRONT. BY LATE SUNDAY INTO MONDAY...A FAIRLY POTENT PACIFIC LOW
PRESSURE SYSTEM TRACKS ACROSS SOUTHERN UTAH ON THE GFS. CURRENT
ECMWF KEEPS A MORE PROGRESSIVE OPEN WAVE MONDAY...THEN CLOSES OFF
A LOW TUESDAY MORNING. IT ALSO TRACKS THE LOW FURTHER NORTH THAN
THE GFS...BUT BOTH ARE PAINTING FAIRLY HIGH QPF FOR THE NEBRASKA
PANHANDLE AND AREAS EAST OF THE LARAMIE RANGE. AS A RESULT I WENT
HIGHER ON POPS FOR MONDAY INTO TUESDAY.
FIRE WEATHER...
NO MAJOR CONCERNS ANTICIPATED TODAY THROUGH THURSDAY AS MIN
RELATIVE HUMIDITIES EXPECTED TO REMAIN GENERALLY ABOVE CRITICAL
THRESHOLDS. RECENT RAINS HAVE HELPED TO GREEN UP FUELS SOMEWHAT.
MAIN CONCERN WILL BE GUSTY WINDS THIS AFTERNOON AND AGAIN WEDS
AFTERNOON MAINLY OVER THE LOWER ELEVATIONS OF CARBON COUNTY INTO
ALBANY COUNTY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RE
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1051 AM MDT TUE MAY 1 2012
.DISCUSSION...
SHOWERS...GENERALLY SPRINKLES...CONTINUE THIS AT MID MORNING OVER
THE PANHANDLE AS WELL AS UNDER THE BAROCLINIC CLOUD BAND FROM CARBON
TO CONVERSE COUNTIES. A SHORTWAVE AT MID MORNING EXTENDED FROM
NORTHEAST TO SOUTH CENTRAL WYOMING...WITH THE CLOUDS AND SHOWERS
AHEAD OF THE FEATURE. MODELS MOVE THE SHORTWAVE TROUGH EAST AND
THROUGH THE ENTIRE CWA THIS EVENING. AN ASSOCIATED SURFACE COLD
FRONT WAS THROUGH ALL BUT THE SOUTHERN PANHANDLE AT 16Z. WEST TO
NORTHWEST WINDS BEHIND THE FRONT WILL GUST AS HIGH AS 45 MPH.
BUMPED UP POPS SLIGHTLY FOR THE REST OF THE DAY AND OTHERWISE MADE
ONLY MINOR CHANGES TO THE FIRST PERIOD OF THE FORECAST IN A RECENT
UPDATE.
&&
.AVIATION...12Z TAFS...
VFR CONDITIONS FOR MOST LOCATIONS...THE EXCEPTION BEING KRWL.
LATEST HRRR GUIDANCE CONTINUES TO FORECAST MVFR CONDITIONS OUT
THAT WAY AS A COLD FRONT APPROACHES. LOOK FOR LOWERING CONDITIONS
AROUND THE 15Z TIME FRAME. WILL CONTINUE TO MONITOR FOR ANY LOWER
CONDITIONS. EXPECT AFTERNOON CONVECTION ACROSS SOUTHEAST WYOMING.
HARD TO PINPOINT EXACT TIMING AND LOCATION...SO WILL CONTINUE VCTS
WORDING IN TAFS.
&&
.PREV DISCUSSION... /ISSUED 214 AM MDT TUE MAY 1 2012/
SHORT TERM...TODAY THROUGH THURSDAY...
A GENERALLY WEST-SOUTHWESTERLY FLOW ALOFT WILL REMAIN OVER THE CWA
THIS PERIOD WITH A FEW WEAK IMPULSES EMBEDDED IN THIS FLOW PASSING
ACROSS OVER THE NEXT FEW DAYS. ONE IMPULSE WILL PASS ACROSS THIS
AFTERNOON AND EVENING AND SHOULD BRING SOME SHOWERS AND MAYBE A
COUPLE WEAK STORMS TO MAINLY THE MOUNTAINS...WITH A FEW STRAYING
OVER THE HIGH PLAINS. A BETTER CHANCE FOR ACTIVITY ON WEDS AS A
JET STREAK SHOULD RIDE ACROSS AHEAD OF A MORE SIGNIFICANT
SHORTWAVE THAT WILL MOVE ACROSS IDAHO INTO MONTANA AND NRN
WYOMING. INSTABILITIES REMAINING RATHER LOW SO EXPECT MAINLY
SHOWERS ALONG WITH ISOLATED STORMS. CLEARING OUT FOR A TIME WEDS
NIGHT INTO THURSDAY THEN SHOULD SEE SOME MORE ACTIVITY DEVELOP
INITIALLY OVER THE MOUNTAINS AS WEAK SFC BOUNDARY PUSHES AGAINST
THE MTNS AND ENHANCES UPSLOPE FLOW...WITH SCTD SHOWERS AND TSTRMS
SPREADING OVER THE PLAINS BY LATE IN THE DAY.
ONLY OTHER THING TO MENTION WILL BE SOME GUSTY WINDS AROUND THE
MTNS TODAY AS DECENT MID-LEVEL FLOW MIXES DOWN. SOME GUSTS AROUND
50 MPH POSSIBLE IN WIND-FAVORED AREAS.
LONG TERM...THURSDAY NIGHT THROUGH MONDAY...
LOOKS LIKE A FAIRLY WET EXTENDED PERIOD UPCOMING. FRIDAY LOOKS TO
BE DRY WITH A SLOW MOVING TROUGH OVER THE WEST COAST. BY SATURDAY
AFTERNOON THE GFS IS SHOWING A BACKDOOR FRONT LYING UP AGAINST THE
LARAMIE RANGE WITH MOIST LOW LEVEL SOUTHEASTERLY FLOW INTO THE
PANHANDLE. THIS SET UP SHOULD GIVE US INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS AS UPPER SHORTWAVES INTERACT WITH THE
FRONT. BY LATE SUNDAY INTO MONDAY...A FAIRLY POTENT PACIFIC LOW
PRESSURE SYSTEM TRACKS ACROSS SOUTHERN UTAH ON THE GFS. CURRENT
ECMWF KEEPS A MORE PROGRESSIVE OPEN WAVE MONDAY...THEN CLOSES OFF
A LOW TUESDAY MORNING. IT ALSO TRACKS THE LOW FURTHER NORTH THAN
THE GFS...BUT BOTH ARE PAINTING FAIRLY HIGH QPF FOR THE NEBRASKA
PANHANDLE AND AREAS EAST OF THE LARAMIE RANGE. AS A RESULT I WENT
HIGHER ON POPS FOR MONDAY INTO TUESDAY.
&&
FIRE WEATHER...
NO MAJOR CONCERNS ANTICIPATED TODAY THROUGH THURSDAY AS MIN
RELATIVE HUMIDITIES EXPECTED TO REMAIN GENERALLY ABOVE CRITICAL
THRESHOLDS. RECENT RAINS HAVE HELPED TO GREEN UP FUELS SOMEWHAT.
MAIN CONCERN WILL BE GUSTY WINDS THIS AFTERNOON AND AGAIN WEDS
AFTERNOON MAINLY OVER THE LOWER ELEVATIONS OF CARBON COUNTY INTO
ALBANY COUNTY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RE
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
600 AM MDT TUE MAY 1 2012
.AVIATION...12Z TAFS...
VFR CONDITIONS FOR MOST LOCATIONS...THE EXCEPTION BEING KRWL.
LATEST HRRR GUIDANCE CONTINUES TO FORECAST MVFR CONDITIONS OUT
THAT WAY AS A COLD FRONT APPROACHES. LOOK FOR LOWERING CONDITIONS
AROUND THE 15Z TIME FRAME. WILL CONTINUE TO MONITOR FOR ANY LOWER
CONDITIONS. EXPECT AFTERNOON CONVECTION ACROSS SOUTHEAST WYOMING.
HARD TO PINPOINT EXACT TIMING AND LOCATION...SO WILL CONTINUE VCTS
WORDING IN TAFS.
&&
.PREV DISCUSSION... /ISSUED 214 AM MDT TUE MAY 1 2012/
SHORT TERM...TODAY THROUGH THURSDAY...
A GENERALLY WEST-SOUTHWESTERLY FLOW ALOFT WILL REMAIN OVER THE CWA
THIS PERIOD WITH A FEW WEAK IMPULSES EMBEDDED IN THIS FLOW PASSING
ACROSS OVER THE NEXT FEW DAYS. ONE IMPULSE WILL PASS ACROSS THIS
AFTERNOON AND EVENING AND SHOULD BRING SOME SHOWERS AND MAYBE A
COUPLE WEAK STORMS TO MAINLY THE MOUNTAINS...WITH A FEW STRAYING
OVER THE HIGH PLAINS. A BETTER CHANCE FOR ACTIVITY ON WEDS AS A
JET STREAK SHOULD RIDE ACROSS AHEAD OF A MORE SIGNIFICANT
SHORTWAVE THAT WILL MOVE ACROSS IDAHO INTO MONTANA AND NRN
WYOMING. INSTABILITIES REMAINING RATHER LOW SO EXPECT MAINLY
SHOWERS ALONG WITH ISOLATED STORMS. CLEARING OUT FOR A TIME WEDS
NIGHT INTO THURSDAY THEN SHOULD SEE SOME MORE ACTIVITY DEVELOP
INITIALLY OVER THE MOUNTAINS AS WEAK SFC BOUNDARY PUSHES AGAINST
THE MTNS AND ENHANCES UPSLOPE FLOW...WITH SCTD SHOWERS AND TSTRMS
SPREADING OVER THE PLAINS BY LATE IN THE DAY.
ONLY OTHER THING TO MENTION WILL BE SOME GUSTY WINDS AROUND THE
MTNS TODAY AS DECENT MID-LEVEL FLOW MIXES DOWN. SOME GUSTS AROUND
50 MPH POSSIBLE IN WIND-FAVORED AREAS.
LONG TERM...THURSDAY NIGHT THROUGH MONDAY...
LOOKS LIKE A FAIRLY WET EXTENDED PERIOD UPCOMING. FRIDAY LOOKS TO
BE DRY WITH A SLOW MOVING TROUGH OVER THE WEST COAST. BY SATURDAY
AFTERNOON THE GFS IS SHOWING A BACKDOOR FRONT LYING UP AGAINST THE
LARAMIE RANGE WITH MOIST LOW LEVEL SOUTHEASTERLY FLOW INTO THE
PANHANDLE. THIS SET UP SHOULD GIVE US INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS AS UPPER SHORTWAVES INTERACT WITH THE
FRONT. BY LATE SUNDAY INTO MONDAY...A FAIRLY POTENT PACIFIC LOW
PRESSURE SYSTEM TRACKS ACROSS SOUTHERN UTAH ON THE GFS. CURRENT
ECMWF KEEPS A MORE PROGRESSIVE OPEN WAVE MONDAY...THEN CLOSES OFF
A LOW TUESDAY MORNING. IT ALSO TRACKS THE LOW FURTHER NORTH THAN
THE GFS...BUT BOTH ARE PAINTING FAIRLY HIGH QPF FOR THE NEBRASKA
PANHANDLE AND AREAS EAST OF THE LARAMIE RANGE. AS A RESULT I WENT
HIGHER ON POPS FOR MONDAY INTO TUESDAY.
&&
FIRE WEATHER...
NO MAJOR CONCERNS ANTICIPATED TODAY THROUGH THURSDAY AS MIN
RELATIVE HUMIDITIES EXPECTED TO REMAIN GENERALLY ABOVE CRITICAL
THRESHOLDS. RECENT RAINS HAVE HELPED TO GREEN UP FUELS SOMEWHAT.
MAIN CONCERN WILL BE GUSTY WINDS THIS AFTERNOON AND AGAIN WEDS
AFTERNOON MAINLY OVER THE LOWER ELEVATIONS OF CARBON COUNTY INTO
ALBANY COUNTY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RE
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
214 AM MDT TUE MAY 1 2012
.SHORT TERM...TODAY THROUGH THURSDAY...
A GENERALLY WEST-SOUTHWESTERLY FLOW ALOFT WILL REMAIN OVER THE CWA
THIS PERIOD WITH A FEW WEAK IMPULSES EMBEDDED IN THIS FLOW PASSING
ACROSS OVER THE NEXT FEW DAYS. ONE IMPULSE WILL PASS ACROSS THIS
AFTERNOON AND EVENING AND SHOULD BRING SOME SHOWERS AND MAYBE A
COUPLE WEAK STORMS TO MAINLY THE MOUNTAINS...WITH A FEW STRAYING
OVER THE HIGH PLAINS. A BETTER CHANCE FOR ACTIVITY ON WEDS AS A
JET STREAK SHOULD RIDE ACROSS AHEAD OF A MORE SIGNIFICANT
SHORTWAVE THAT WILL MOVE ACROSS IDAHO INTO MONTANA AND NRN
WYOMING. INSTABILITIES REMAINING RATHER LOW SO EXPECT MAINLY
SHOWERS ALONG WITH ISOLATED STORMS. CLEARING OUT FOR A TIME WEDS
NIGHT INTO THURSDAY THEN SHOULD SEE SOME MORE ACTIVITY DEVELOP
INITIALLY OVER THE MOUNTAINS AS WEAK SFC BOUNDARY PUSHES AGAINST
THE MTNS AND ENHANCES UPSLOPE FLOW...WITH SCTD SHOWERS AND TSTRMS
SPREADING OVER THE PLAINS BY LATE IN THE DAY.
ONLY OTHER THING TO MENTION WILL BE SOME GUSTY WINDS AROUND THE
MTNS TODAY AS DECENT MID-LEVEL FLOW MIXES DOWN. SOME GUSTS AROUND
50 MPH POSSIBLE IN WIND-FAVORED AREAS.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY...
LOOKS LIKE A FAIRLY WET EXTENDED PERIOD UPCOMING. FRIDAY LOOKS TO
BE DRY WITH A SLOW MOVING TROUGH OVER THE WEST COAST. BY SATURDAY
AFTERNOON THE GFS IS SHOWING A BACKDOOR FRONT LYING UP AGAINST THE
LARAMIE RANGE WITH MOIST LOW LEVEL SOUTHEASTERLY FLOW INTO THE
PANHANDLE. THIS SET UP SHOULD GIVE US INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS AS UPPER SHORTWAVES INTERACT WITH THE
FRONT. BY LATE SUNDAY INTO MONDAY...A FAIRLY POTENT PACIFIC LOW
PRESSURE SYSTEM TRACKS ACROSS SOUTHERN UTAH ON THE GFS. CURRENT
ECMWF KEEPS A MORE PROGRESSIVE OPEN WAVE MONDAY...THEN CLOSES OFF
A LOW TUESDAY MORNING. IT ALSO TRACKS THE LOW FURTHER NORTH THAN
THE GFS...BUT BOTH ARE PAINTING FAIRLY HIGH QPF FOR THE NEBRASKA
PANHANDLE AND AREAS EAST OF THE LARAMIE RANGE. AS A RESULT I WENT
HIGHER ON POPS FOR MONDAY INTO TUESDAY.
&&
.AVIATION...06Z TAFS...
VFR CONDITIONS FOR MOST LOCATIONS...THE EXCEPTION BEING KRWL.
LATEST HRRR GUIDANCE SUGGESTING MVFR CONDITIONS OUT THAT WAY AS A
COLD FRONT APPROACHES AROUND THE 12-13Z TIMEFRAME. WILL CONTINUE
TO MONITOR FOR ANY LOWER CONDITIONS. EXPECT AFTERNOON CONVECTION
ACROSS SOUTHEAST WYOMING. HARD TO PINPOINT EXACT TIMING AND
LOCATION...SO WILL CONTINUE VCTS WORDING IN TAFS.
&&
.FIRE WEATHER...
NO MAJOR CONCERNS ANTICIPATED TODAY THROUGH THURSDAY AS MIN
RELATIVE HUMIDITIES EXPECTED TO REMAIN GENERALLY ABOVE CRITICAL
THRESHOLDS. RECENT RAINS HAVE HELPED TO GREENUP FUELS SOMEWHAT.
MAIN CONCERN WILL BE GUSTY WINDS THIS AFTERNOON AND AGAIN WEDS
AFTERNOON MAINLY OVER THE LOWER ELEVATIONS OF CARBON COUNTY INTO
ALBANY COUNTY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RE
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1058 PM MDT MON APR 30 2012
.AVIATION...06Z TAFS
VFR CONDITIONS FOR MOST LOCATIONS...THE EXCEPTION BEING KRWL.
LATEST HRRR GUIDANCE SUGGESTING MVFR CONDITIONS OUT THAT WAY AS A
COLD FRONT APPROACHES AROUND THE 12-13Z TIMEFRAME. WILL CONTINUE
TO MONITOR FOR ANY LOWER CONDITIONS. EXPECT AFTERNOON CONVECTION
ACROSS SOUTHEAST WYOMING. HARD TO PINPOINT EXACT TIMING AND
LOCATION...SO WILL CONTINUE VCTS WORDING IN TAFS.
CLAYCOMB
&&
PREV DISCUSSION... /ISSUED 243 PM MDT MON APR 30 2012/
SHORT TERM...TONIGHT THROUGH WEDNESDAY...
THE FLOW ALOFT WILL SLOWLY BACK THROUGH WEDNESDAY AS HEIGHTS SLOWLY
RISE. A SHORTWAVE TROUGH WILL MOVE ACROSS THE CWA EARLY TONIGHT
WITH AN INCREASE IN MID AND HIGH CLOUDS ASSOCIATED. A COLD FRONT
WILL MOVE ACROSS THE CWA LATE TONIGHT THROUGH EARLY AFTERNOON
TUESDAY. THE FRONT WILL THEN BE JUST TO OUR SOUTH AND EAST
THROUGH WEDNESDAY. THE 300 MB JET WILL BE OVER THE AREA DURING
THAT TIME AND MOISTURE AND LIFT WILL INCREASE OVER THE REGION.
SOME SHOWERS MAY DEVELOP AS EARLY AS LATE TONIGHT OVER CARBON
COUNTY AND THEN SPREAD EAST AND NORTHEAST DURING THE DAY. BY THE
AFTERNOON A WIDELY SCATTERED COVERAGE OF SHOWERS AND STORMS WILL
BE OVER THE CWA. ACTIVITY TO THE EAST OF THE LARAMIE RANGE SHOULD
BE FAIRLY HIGH BASED WITH ONLY LIGHT RAINFALL. INSTABILITY IS ONLY
MARGINAL OVER THE CWA TUESDAY AFTERNOON AND EARLY EVENING.
THE PROXIMITY OF THE 300 MB JET AND THE LOW LEVEL THETA AXIS SHOULD
HELP KEEP SOME SHOWERS GOING TUESDAY NIGHT AND WEDNESDAY MORNING
OVER MAINLY THE WEST AND NORTH PARTS OF THE CWA. MOISTURE AND
INSTABILITY ARE MORE FAVORABLE FOR SLIGHTLY STRONGER AND WETTER
ACTIVITY BY WEDNESDAY AFTERNOON WITH A PRONOUNCED LOW LEVEL THETA
RIDGE AXIS OVER THE SOUTH PART OF THE CWA AND DIFFLUENT FLOW ALOFT.
HAVE GENERALLY BUMPED UP POPS AND CLOUD COVER THROUGH TUESDAY
THROUGH WEDNESDAY. WESTERLY SURFACE WINDS WILL GUST AS HIGH AS 50
MPH ALONG AND WEST OF THE LARAMIE RANGE TUESDAY WITH SLIGHTLY LOWER
SPEEDS EXPECTED FOR WEDNESDAY. TEMPERATURES WILL CONTINUE TO BE
MILD THROUGH WEDNESDAY WITH READINGS A BIT COOLER OVER THE CWA ON
WEDNESDAY.
LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
ZONAL MIDLEVEL FLOW WILL BE OVER THE AREA THROUGH FRIDAY. EXPECT A
SLIGHT CHANCE OF AFTN SHOWERS AND TSTMS ON THURS AND FRI...MAINLY
ALONG AND EAST OF THE LARAMIE RANGE. ANY TSTMS THAT DEVELOP DURING
THE AFTN WILL LIKELY BE WEAK AND ISOLATED AS THE LLVL MOISTURE AND
INSTABILITY IS LACKING OVER THE PLAINS. HIGH TEMPS WILL BE ABOVE
NORMAL WITH 700MB TEMPS AROUND 6C/9C ON THURS/FRI. A LONGWAVE
TROUGH WILL AMPLIFY INTO THE PACIFIC NORTHWEST ON FRI NIGHT AND
SAT...INCREASING THE SOUTHWESTERLY MIDLEVEL FLOW OVER WY. SFC
PRESSURE FALLS OVER THE INTERMOUNTAIN WEST COMBINED WITH PRESSURE
RISES OVER THE NORTHERN PLAINS WILL BEGIN TO TRANSPORT LLVL
MOISTURE IN SE SFC WINDS INTO AREAS EAST OF THE LARAMIE RANGE. RAIN
CHANCES OVER THE WEEKEND WILL LIKELY BE ON THE INCREASE WITH
PERSISTENT UPSLOPE E/SE FLOW AND DYNAMICS FROM THE TROUGH TO THE
WEST. THERE IS THE POTENTIAL FOR STRONG/MARGINALLY SEVERE TSTMS TO
DEVELOP ON SAT AFTN OVER THE PLAINS. THE GFS SHOWS 1000-1500 J/KG OF
CAPE OVER THE PLAINS WITH AROUND 45 KTS OF DEEP LAYER SHEAR. THE
GENERAL CONSENSUS BETWEEN THE LONG RANGE MODELS IS TO MOVE THE
CLOSED LOW OVER THE INTERMOUNTAIN WEST VERY SLOWLY EASTWARD.
SUNDAY HAS THE POTENTIAL TO PRODUCE SEVERE TSTMS OVER MAINLY THE
NEBRASKA PANHANDLE...WITH SIMILAR SEVERE PARAMETERS AS SATURDAY. THE
TIMING OF A COLD FRONTAL PASSAGE LATE NEXT WEEKEND WILL BE
DEPENDENT ON THE EASTWARD PROGRESSION OF THE UPPER LEVEL
SYSTEM...WITH A CHANGE FROM CONVECTIVE TO MORE STRATIFORM PRECIP
BEHIND THE FRONT.
&&
FIRE WEATHER...
THE WARM...DRY AND WINDY WEATHER WILL CONTINUE OVER THE CWA INTO
THE EVENING HOURS WITH NEAR CRITICAL FIRE WEATHER CONDITIONS.
THE WEATHER WILL BE SIMILAR TUESDAY AND WEDNESDAY...WITH THE MAIN
DIFFERENCE BEING SLIGHTLY HIGHER RELATIVE HUMIDITY VALUES. IN
ADDITION...A WIDELY SCATTERED COVERAGE OF MAINLY HIGH BASED SHOWERS
AND STORMS WILL BE OVER THE AREA TUESDAY AFTERNOON AND EVENING. THE
ACTIVITY WILL BE WIDESPREAD WITH A BETTER CHANCE OF WETTING RAINFALL
FOR WEDNESDAY AFTERNOON AND EVENING. DRIER CONDITIONS ARE EXPECTED
FOR THURSDAY AND FRIDAY BEFORE A BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS RETURNS FOR THE WEEKEND.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...WEILAND
LONG TERM/AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS NEW YORK NY
149 AM EDT THU MAY 3 2012
.SYNOPSIS...
A HIGH PRESSURE SYSTEM OFF THE NEW ENGLAND COAST AND A WARM FRONT
EXTENDING SOUTHEAST ACROSS NEW YORK AND PENNSYLVANIA WILL REMAIN
NEARLY STATIONARY THROUGH THURSDAY THEN MOVE EAST ON FRIDAY. LOW
PRESSURE OVER NORTHERN NEW YORK FRIDAY NIGHT WILL REFORM SOUTH OF
LONG ISLAND SATURDAY. HIGH PRESSURE NORTH OF THE GREAT LAKES WILL
MOVE SLOWLY SOUTHEAST SUNDAY AND MONDAY. A LOW PRESSURE SYSTEM WILL
MOVE NORTHEAST TOWARD THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
TSTMS BEARING DOWN ON THE CWA ATTM. FOLLOWED THE HRRR FOR GENERAL
TIMING IN THE GRIDS. MAIN THREAT WILL BE LOC HVY RAIN AND
LIGHTNING IN THE ELEVATED CONVECTION.
TEMPS NEARLY STEADY THRU 6AM.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
SHORTWAVE ENERGY EXITS WITH FURTHER WEAKENING OF CANADIAN
MARITIME HIGH PRESSURE. LOW LEVEL MOISTURE REMAINS HIGH WITH LOW
CLOUDS STICKING AROUND THE FORECAST AREA THROUGH MUCH OF THE DAY.
THERE IS CHANCE THAT SOME AREAS COULD BREAK OUT OF THE CLOUD COVER
DURING THE AFTERNOON...WHICH WOULD WARM TEMPERATURES WARMER THAN
FORECAST. HIGHS ARE EXPECTED TO RANGE FROM THE LOWER 60S TO UPPER
60S...WITH THE COOLER TEMPERATURES TO THE EAST AND THE WARMEST
TEMPERATURES TO THE WEST. WITH MOSTLY CLOUDY/CLOUDY SKIES FORECAST
FOR THE DAY...HAVE FOLLOWED THE SLIGHTLY COOLER NAM GUIDANCE.
A FRONTAL BOUNDARY AND LOW PRESSURE SYSTEM START TO APPROACH
THURSDAY NIGHT...SO POPS GRADUALLY INCREASE THROUGH THE NIGHT.
AGAIN LOOKING AT CLOUDY SKIES WITH TEMPERATURES NOT FALLING VERY
MUCH. ONCE AGAIN STUCK WITH THE NAM GUIDANCE FOR LOWS...AS
TEMPERATURES RANGE FROM THE UPPER 40S TO MIDDLE 50S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
UNSETTLED WEATHER IS FORECAST FRIDAY THROUGH SATURDAY THEN TUESDAY
AND WEDNESDAY.
BECAUSE ALL WEATHER FEATURES ARE FORECAST TO REMAIN WEAK THROUGHOUT
THIS PERIOD...TIMING THE CHANCES OF RAIN WILL BE DIFFICULT.
FRIDAY...FORECAST MODELS SHOW HEIGHTS GRADUALLY LOWERING AS WEAK LOW
PRES MVS ACROSS NORTHERN NY STATE. INCLUDED A 40 PCT POP FOR SCT
SHOWERS AND TSTMS. BUST POTENTIAL FOR HIGH TEMPS BASED ON FCST CLOUD
COVER AND WIND DIRECTION WITH THE PASSAGE OF A WARM FRONT.
SATURDAY...MODELS SHOW THIS LOW REFORMING S OF LONG ISLAND AS A NE
WIND FLOW DEVELOPS...MAKING FOR A DAMP CHILLY DAY. LIGHT RAIN OR
DRIZZLE CANNOT BE RULED OUT.
SUNDAY INTO MONDAY...POPS WERE REMOVED FROM THE FCST AS A HIGH PRES
RIDGE BUILDS SE ACROSS THE AREA.
TUESDAY INTO WEDNESDAY...AS THIS HIGH MVS OFFSHORE AND AN UPSTREAM
TROUGH AMPLIFIES...ISENTROPIC LIFT WILL INCREASE CAUSING CLOUDS TO
LOWER AND THICKEN WITH OUR NEXT CHC OF RAIN.
KEEP THOSE UMBRELLAS HANDY ALTHOUGH WIDESPREAD SIGNIFICANT RAINFALL
ARE NOT ON THE HORIZON WITH ANY WELL DEFINED STORMS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
TSTMS BEARING DOWN ON THE TERMINALS ATTM...WITH IFR VSBY. ONE TSTM
HEADED TOWARD KEWR COULD PRODUCE GUSTS UP TO 30 KT THERE...
OTHERWISE NOT EXPECTING SFC WIND IMPACTS AT OTHER TERMINALS.
AFTER THESE STORMS PASS...GENERALLY IFR TO LIFR CONDS ON TAP
THROUGH THU MORNING...THEN CONDS IMPROVE TO MVFR LATE IN THE
MORNING...THEN TO VFR BY AFTERNOON FOR MOST SITES.
GENERALLY SE WINDS AT 4-8 KT TONIGHT...THEN SOUTHERLY WINDS 5-10
KT THU MORNING.
ANOTHER ROUND OF RAIN EXPECTED THU NIGHT WITH MVFR OR LOWER CONDS.
OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY...
.LATE THU NIGHT...MVFR...POSSIBLY IFR. CHANCE OF SHOWERS.
.FRI...GENERALLY MVFR OR LOWER. AREAS WEST OF THE HUDSON COULD
BREAK OUT TO VFR IN THE AFTN. CHANCE OF SHOWERS IN THE
MORNING...THEN A CHANCE OF TSTMS IN THE AFTERNOON.
.SAT-MON...MAINLY VFR. SCT SHOWERS ON SAT.
&&
.MARINE...
PRESSURE GRADIENT CONTINUES TO WEAKEN AS HIGH PRESSURE TO THE
EAST WEAKENS THROUGH THURSDAY. EXPECT SUB-SCA CONDITIONS ON THE
AREA WATERS THROUGH THURSDAY NIGHT.
THE NEXT CHANCE FOR A SMALL CRAFT ADVISORY WILL BE SATURDAY
AFTERNOON THROUGH SUNDAY MORNING AS A LOW PRESSURE SYSTEM DEVELOPS
SOUTH OF LONG ISLAND. WITH HIGH PRESSURE MOVING SOUTHEAST TOWARD THE
AREA...AN INCREASING NORTHEAST PRESSURE GRADIENT WILL CAUSE
INCREASING NE WINDS AND BUILDING SEAS. STAY TUNED.
OTHERWISE...WINDS AND SEAS ARE FORECAST TO REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA.
&&
.HYDROLOGY...
BETWEEN A QUARTER TO HALF INCH OF QPF IS FORECAST THROUGH THURSDAY
NIGHT AS RAIN AND SHOWERS MOVE ACROSS THE FORECAST AREA.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BC/GC
NEAR TERM...12
SHORT TERM...BC
LONG TERM...GC
AVIATION...GOODMAN
MARINE...BC/GC
HYDROLOGY...BC/GC
AREA FORECAST DISCUSSION
NWS NEW YORK NY
103 AM EDT THU MAY 3 2012
.SYNOPSIS...
A HIGH PRESSURE SYSTEM OFF THE NEW ENGLAND COAST AND A WARM FRONT
EXTENDING SOUTHEAST ACROSS NEW YORK AND PENNSYLVANIA WILL REMAIN
NEARLY STATIONARY THROUGH THURSDAY THEN MOVE EAST ON FRIDAY. LOW
PRESSURE OVER NORTHERN NEW YORK FRIDAY NIGHT WILL REFORM SOUTH OF
LONG ISLAND SATURDAY. HIGH PRESSURE NORTH OF THE GREAT LAKES WILL
MOVE SLOWLY SOUTHEAST SUNDAY AND MONDAY. A LOW PRESSURE SYSTEM WILL
MOVE NORTHEAST TOWARD THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
TSTMS BEARING DOWN ON THE CWA ATTM. FOLLOWED THE HRRR FOR GENERAL
TIMING IN THE GRIDS. MAIN THREAT WILL BE LOC HVY RAIN AND
LIGHTNING IN THE ELEVATED CONVECTION.
TEMPS NEARLY STEADY THRU 6AM.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
SHORTWAVE ENERGY EXITS WITH FURTHER WEAKENING OF CANADIAN
MARITIME HIGH PRESSURE. LOW LEVEL MOISTURE REMAINS HIGH WITH LOW
CLOUDS STICKING AROUND THE FORECAST AREA THROUGH MUCH OF THE DAY.
THERE IS CHANCE THAT SOME AREAS COULD BREAK OUT OF THE CLOUD COVER
DURING THE AFTERNOON...WHICH WOULD WARM TEMPERATURES WARMER THAN
FORECAST. HIGHS ARE EXPECTED TO RANGE FROM THE LOWER 60S TO UPPER
60S...WITH THE COOLER TEMPERATURES TO THE EAST AND THE WARMEST
TEMPERATURES TO THE WEST. WITH MOSTLY CLOUDY/CLOUDY SKIES FORECAST
FOR THE DAY...HAVE FOLLOWED THE SLIGHTLY COOLER NAM GUIDANCE.
A FRONTAL BOUNDARY AND LOW PRESSURE SYSTEM START TO APPROACH
THURSDAY NIGHT...SO POPS GRADUALLY INCREASE THROUGH THE NIGHT.
AGAIN LOOKING AT CLOUDY SKIES WITH TEMPERATURES NOT FALLING VERY
MUCH. ONCE AGAIN STUCK WITH THE NAM GUIDANCE FOR LOWS...AS
TEMPERATURES RANGE FROM THE UPPER 40S TO MIDDLE 50S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
UNSETTLED WEATHER IS FORECAST FRIDAY THROUGH SATURDAY THEN TUESDAY
AND WEDNESDAY.
BECAUSE ALL WEATHER FEATURES ARE FORECAST TO REMAIN WEAK THROUGHOUT
THIS PERIOD...TIMING THE CHANCES OF RAIN WILL BE DIFFICULT.
FRIDAY...FORECAST MODELS SHOW HEIGHTS GRADUALLY LOWERING AS WEAK LOW
PRES MVS ACROSS NORTHERN NY STATE. INCLUDED A 40 PCT POP FOR SCT
SHOWERS AND TSTMS. BUST POTENTIAL FOR HIGH TEMPS BASED ON FCST CLOUD
COVER AND WIND DIRECTION WITH THE PASSAGE OF A WARM FRONT.
SATURDAY...MODELS SHOW THIS LOW REFORMING S OF LONG ISLAND AS A NE
WIND FLOW DEVELOPS...MAKING FOR A DAMP CHILLY DAY. LIGHT RAIN OR
DRIZZLE CANNOT BE RULED OUT.
SUNDAY INTO MONDAY...POPS WERE REMOVED FROM THE FCST AS A HIGH PRES
RIDGE BUILDS SE ACROSS THE AREA.
TUESDAY INTO WEDNESDAY...AS THIS HIGH MVS OFFSHORE AND AN UPSTREAM
TROUGH AMPLIFIES...ISENTROPIC LIFT WILL INCREASE CAUSING CLOUDS TO
LOWER AND THICKEN WITH OUR NEXT CHC OF RAIN.
KEEP THOSE UMBRELLAS HANDY ALTHOUGH WIDESPREAD SIGNIFICANT RAINFALL
ARE NOT ON THE HORIZON WITH ANY WELL DEFINED STORMS.
&&
.AVIATION /05Z THURSDAY THROUGH MONDAY/...
UNSETTLED WEATHER THROUGH THE TAF PERIOD...WITH MVFR CIGS
LOWERING TO IFR AFTER MIDNIGHT. THEN RAIN MOVES INTO THE REGION
THEREAFTER. CANNOT RULE OUT A RUMBLE OF THUNDER...BUT CONFIDENCE
TOO LOW TO WARRANT MENTIONING TS/VCTS IN THE TAF...AS THE
THUNDERSTORMS OVER CENTRAL PA LOOK TO PASS WELL SOUTH AND WEST OF
THE TERMINALS. GENERALLY IFR TO LIFR CONDS ON TAP THROUGH
THURSDAY MORNING...THEN CONDS IMPROVE TO MVFR LATE IN THE
MORNING...THEN TO VFR BY AFTERNOON FOR MOST TAF SITES.
GENERALLY E TO SE WINDS AT 4-8 KT TONIGHT...THEN SOUTHERLY WINDS
INCREASE TO 5-10 KT THURSDAY MORNING.
ANOTHER ROUND OF RAIN EXPECTED THURSDAY NIGHT WITH SUB-VFR CONDS.
OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.THU NIGHT...MVFR...POSSIBLY IFR. CHANCE OF SHOWERS LATE.
.FRI...GENERALLY MVFR OR LOWER. AREAS WEST OF THE HUDSON COULD
BREAK OUT TO VFR IN THE AFTN. CHANCE OF SHOWERS MORNING...THEN A
CHANCE OF TSTMS AFT.
.SAT-MON...MAINLY VFR. SCT SHOWERS SAT.
&&
.MARINE...
PRESSURE GRADIENT CONTINUES TO WEAKEN AS HIGH PRESSURE TO THE
EAST WEAKENS THROUGH THURSDAY. EXPECT SUB-SCA CONDITIONS ON THE
AREA WATERS THROUGH THURSDAY NIGHT.
THE NEXT CHANCE FOR A SMALL CRAFT ADVISORY WILL BE SATURDAY
AFTERNOON THROUGH SUNDAY MORNING AS A LOW PRESSURE SYSTEM DEVELOPS
SOUTH OF LONG ISLAND. WITH HIGH PRESSURE MOVING SOUTHEAST TOWARD THE
AREA...AN INCREASING NORTHEAST PRESSURE GRADIENT WILL CAUSE
INCREASING NE WINDS AND BUILDING SEAS. STAY TUNED.
OTHERWISE...WINDS AND SEAS ARE FORECAST TO REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA.
&&
.HYDROLOGY...
BETWEEN A QUARTER TO HALF INCH OF QPF IS FORECAST THROUGH THURSDAY
NIGHT AS RAIN AND SHOWERS MOVE ACROSS THE FORECAST AREA.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BC/GC
NEAR TERM...12
SHORT TERM...BC
LONG TERM...GC
AVIATION...MPS
MARINE...BC/GC
HYDROLOGY...BC/GC
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
127 AM EDT THU MAY 3 2012
.SYNOPSIS...
A WARM FRONT TO OUR SOUTH AND WEST WILL MOVE VERY SLOWLY EASTWARD
OVERNIGHT AND THURSDAY. LOW PRESSURE WILL CROSS THE LOWER GREAT
LAKES AND SOUTHERN CANADA THROUGH THE EARLY PART OF THE WEEKEND. A
COLD FRONT ATTACHED TO THE LOW WILL CROSS THE AREA SATURDAY. THIS
WILL BE FOLLOWED BY HIGH PRESSURE FOR THE REST OF THE WEEKEND AND
INTO EARLY NEXT WEEK. ANOTHER DISTURBANCE WILL ARRIVE OVER THE
REGION NEXT TUESDAY INTO WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE LAST OF THE ORGANIZED CONVECTION IS MOVING THROUGH NORTHERN
NEW JERSEY EARLY THIS MORNING. THE LIGHTNING HAS DECREASED
STEADILY AS THE ACTIVITY HAS MOVED SOUTHEAST. HOWEVER...DUAL POL
PRODUCTS SUGGEST THAT SOME OF THE STRONGER CONVECTIVE CELLS COULD
HAVE SOME SMALL HAIL. THIS COULD PERSIST THROUGH ABOUT 230 AM OR
SO...ESPECIALLY WITH NEW CONVECTIVE CELLS DEVELOPING SOUTHEAST OF
THE MAIN BATCH.
THE MAIN THREAT IS STILL HEAVY RAIN...AND RADAR INDICATES AS MUCH
AS AN INCH OF RAIN HAS FALLEN IN LESS THAN AN HOUR WITH SOME OF
THE ACTIVITY. SINCE THE ACTIVITY IS MOVING...NO MORE THAN NUISANCE
FLOODING IS EXPECTED. DOPPLER RADARS SHOW 35 TO 40 KNOT WINDS AT
ABOUT 6000-7000 FEET WITH SOME OF THE CONVECTIVE LOOKING LINE
ACROSS NORTHERN NEW JERSEY. HOWEVER...DUE TO THE STRONG AND MOIST
MARINE INVERSION IN PLACE...THIS HAS YET TO TRANSLATE INTO STRONG
WIND GUSTS AT THE SURFACE.
THE CHANCE OF SHOWERS WAS EXPANDED TO INCLUDE A BIT MORE OF THE
AREA...AS THE LATEST HRRR IS SHOWING THIS TREND. NO OTHER
SIGNIFICANT CHANGES TO WINDS OR TEMPERATURES FOR THE REST OF THE
EARLY MORNING.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THIS EVENING/...
PATCHY FOG AND SOME SHOWERS WILL BEGIN THE DAY AS A DISTURBANCE
MOVES OVERHEAD EARLY. A WARM FRONT WILL BE APPROACHING THE REGION
FROM THE WEST, AND WE ARE EXPECTING THIS FRONT TO PUSH THROUGH THE
FORECAST AREA BY LATE IN THE DAY. A FEW SHOWERS AND ISOLATED
THUNDERSTORMS HAVE BEEN RETAINED IN THE FORECAST FOR THE AFTERNOON
HOURS. THE ONSHORE FLOW AND LOWER CLOUDS MAY HANG ON LONGER
ESPECIALLY ACROSS THE NORTHEASTERN PORTION OF OUR CWA. AS A
RESULT, THE HIGHS WERE ADJUSTED DOWN SOME. IF THE WARM FRONT ENDS
UP LIFTING THROUGH FASTER WITH ENOUGH SUNSHINE RETURNING, THE
TEMPERATURES COULD BE OFF TO THE RACES GIVEN THE RATHER MILD AIR
NOT TO FAR ABOVE THE SURFACE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
A SFC WARM FRONT WILL FINALLY PUSH NORTHWARD ACROSS THE AREA THU
NIGHT AND IT WILL BE FOLLOWED BY A MORE WARM AND HUMID AIR MASS. A
LOW PRESSURE SYSTEM WILL BE JUST NORTH OF THE AREA THU NIGHT AND
IT WILL MOVE ACROSS NORTHERN NEW ENGLAND FRI AND THEN DOWN THE ST
LAWRENCE VALLEY FRI NIGHT. AN ATTACHED COLD FRONT WILL CROSS THE
AREA EARLY SAT. THESE FEATURES WILL BE CLOSE ENOUGH TO THE AREA TO
KEEP SLGT CHC OR CHC POPS ACROSS THE AREA. TEMPERATURES THU NIGHT
INTO SAT WILL REMAIN ABOVE NORMAL WITH HIGH TEMPERATURES IN THE
LOW TO MID 80S IN MOST AREAS. SAT WILL BE A LITTLE COOLER ONCE THE
COLD FRONT PASSES.
A DRIER PERIOD WILL ARRIVE SAT NIGHT INTO EARLY TUESDAY AS A SLOW
MOVING RIDGE OF HIGH PRESSURE MOVES ACROSS THE AREA. TEMPERATURES
DURING THIS PERIOD WILL BE SEASONABLE WITH HIGHS MOSTLY IN THE LOW
TO MID 70S AND OVERNIGHT LOWS IN THE UPPER 40S TO LOW 50S.
ANOTHER DISTURBANCE WILL MOVE TOWARD THE AREA TUE AND REMAIN INTO
THU AS A SFC LOW AND COLD FRONT STALL ALONG THE COAST. THIS WILL
KEEP THE TEMPERATURES NEAR OR A LITTLE BELOW NORMAL FOR EARLY MAY.
POPS WILL BE HELD A SLGT CHC OR LOW CHC ATTM.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
LIFR CONDITIONS REMAIN IN PLACE EARLY THIS MORNING. AN AREA OF
SHOWERS AND THUNDERSTORMS CONTINUES TO WEAKEN AS IT MOVES SOUTHEAST.
THE MAIN THUNDERSTORM THREAT SHOULD BE LIMITED TO KABE THROUGH ABOUT
0800 UTC. ELSEWHERE...THE AIRMASS LOOKS TOO STABLE FOR THUNDER THIS
MORNING.
CONDITIONS SHOULD SLOWLY RISE FROM LIFR TO IFR THROUGH ABOUT 1500
UTC AT ALL LOCATIONS...AND FINALLY TO VFR AROUND 1700 TO 1800 UTC.
THE EXCEPTION COULD BE KACY...WHERE THE IFR CONDITIONS COULD LINGER
JUST OFFSHORE...AND REMAIN CLOSE BY MOST OF THE DAY. THUNDERSTORM
ACTIVITY SHOULD BE FAIRLY LIMITED THIS AFTERNOON AND EVENING...AND
NOT MENTIONED IN THE 0600 UTC FORECASTS.
THE IFR CONDITIONS COME BACK IN FROM EAST TO WEST BETWEEN 0000 UTC
AND 0400 UTC. THERE IS SOME INDICATION THAT THE FOG COULD BE MORE
WIDESPREAD LATE TONIGHT...AND LIFR CONDITIONS ARE EXPECTED AFTER
0600 UTC FRIDAY AT ALL LOCATIONS.
OUTLOOK...
FRIDAY...IMPROVING CIGS/VSBYS AS FRONT PASSES EAST OF THE AREA.
LOWER CONDITIONS FRI NIGHT WITH AREAS OF FOG POSSIBLE.
SATURDAY INTO MONDAY...MOSTLY VFR.
&&
.MARINE...
SEAS HAVE DROPPED BELOW 5 FEET AT 44009. WHILE SEAS MAY TEND TO
OSCILLATE NEAR 5 FEET FOR THE REST OF THE EARLY MORNING...THE
OVERALL TREND APPEARS TO BE DOWN. THUS...THE SMALL CRAFT ADVISORY
WAS CANCELLED.
WITH THE CONTINUED EAST TO SOUTHEAST FLOW, PATCHY FOG MAY DEVELOP
OVER THE WATERS TONIGHT. IN ADDITION, A FEW SHOWERS CAN ALSO BE
EXPECTED TONIGHT AHEAD OF AN APPROACHING WARM FRONT. FOR THURSDAY,
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW ADVISORY CRITERIA. WITH
THE WARM FRONT EXPECTED TO MOVE THROUGH THE AREA LATE TOMORROW,
SHOWERS ARE AGAIN POSSIBLE, ESPECIALLY FOR THE AFTERNOON.
OUTLOOK...
MOSTLY SUB-SCA CONDITIONS WILL BE ON THE WATERS THU NIGHT THROUGH
SAT NIGHT. HIGH PRESSURE BUILDING DOWN FROM CANADA SAT WILL
PROMOTE ONSHORE FLOW SUN-SUN NIGHT. THIS MAY PRODUCE A SHORT
PERIOD OF SCA CONDITIONS SUN WITH SEAS NEAR 5 FT. CONDITIONS WILL
SUBSIDE BACK BELOW SCA MON-TUE.
&&
.TIDES/COASTAL FLOODING...
ASTRONOMICAL TIDES ARE INCREASING THROUGH THIS WEEKEND. ANY PUSH
FROM AN ONSHORE FLOW COULD RAISE WATER LEVELS TO NEAR MINOR TIDAL
FLOOD HEIGHTS. WE WILL MONITOR THIS SITUATION AS WE MOVE THROUGH
THE WEEK.
&&
.EQUIPMENT...
THE ACY ASOS REMAINS OFFLINE DUE TO EQUIPMENT PROBLEMS. THE CLIMATE
DATA IS BEING ESTIMATED FROM NEARBY MESONET SITES.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...O`HARA
NEAR TERM...HAYES
SHORT TERM...GORSE/KLINE
LONG TERM...O`HARA
AVIATION...HAYES/O`HARA
MARINE...HAYES/O`HARA
TIDES/COASTAL FLOODING...RPW
EQUIPMENT...GORSE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
442 AM EDT THU MAY 3 2012
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL GRADUALLY SINK SOUTHWARD LATE IN THE
WEEK...AS A TROUGH OF LOW PRESSURE DEVELOPS INLAND. A COLD FRONT
WILL MOVE INTO THE REGION SATURDAY NIGHT AND SUNDAY...THEN DROP
SOUTH OF THE AREA EARLY NEXT WEEK AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. ANOTHER COLD FRONT COULD MOVE ACROSS THE AREA FROM
THE NORTHWEST DURING THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE SYNOPTIC PATTERN REMAINS AMAZINGLY PERSISTENT FOR THE MIDDLE
OF SPRING WITH A BLOCKING RIDGE STILL SITTING OVER THE EASTERN
CAROLINAS AND WESTERN ATLANTIC. TODAY LOOKS TO BE THE FINAL DAY IN
THIS PATTERN BEFORE A SUBSTANTIAL SHIFT OCCURS. THROUGH DAYBREAK
WE ARE CARRYING WIDESPREAD FOG AWAY FROM THE COAST. THOUGH
VISIBILITIES HAVE THUS FAR ONLY BRIEFLY DROPPED TO 1/4 MILE IN
SPOTS...WE COULD AGAIN SEE A QUICK DENSIFYING TREND AS THE
BOUNDARY LAYER COOLS A BIT FURTHER CLOSER TO DAYBREAK. A LAST
MINUTE DENSE FOG ADVISORY CANNOT BE COMPLETELY RULED OUT.
BY MID TO LATE MORNING ANY LOW CLOUDS AND FOG WILL HAVE BURNED OFF
BUT SOME CUMULUS IS EXPECTED TO DEVELOP SOON THEREAFTER. OTHERWISE
MOSTLY SUNNY SKIES ARE ANTICIPATED. 850 MB TEMPS ARE AROUND 18C
WHICH...USING THE 1000-850 MB THICKNESS CHARTS...GIVES HIGHS
BETWEEN 88 AND 91. THE EXCEPTION AS USUAL WILL BE THE IMMEDIATE
COASTLINE WHERE THE SEABREEZE WILL STOP THE WARMING IN THE LOWER
80S EARLY THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
A STRENGTHENING SHORTWAVE TROUGH LIFTING INTO THE TENNESSEE VALLEY
TONIGHT WILL ERODE THE UPPER RIDGE OVER THE SOUTHEAST UNITED
STATES. SOME MID AND HIGH CLOUDS WILL OVERSPREAD FAR WESTERN ZONES
LATE TONIGHT BUT WE THINK THE BEST FORCING FOR PRECIPITATION WILL
REMAIN JUST TO OUR WEST.
FRIDAY AND FRIDAY NIGHT...DEEP LAYERED RIDGING WILL ERODE AS A SHORT
WAVE TROUGH SHIFTS ACROSS THE REGION. MEANWHILE...A SURFACE TROUGH
WILL FORM IN THE LEE OF THE APPALACHIANS AND SHIFT TOWARD THE COAST
LATE FRIDAY AND FRIDAY NIGHT. MOISTURE PROFILES DO NOT APPEAR ALL
THAT IMPRESSIVE...BUT GIVEN LESS SUBSIDENCE AND WEAK FORCING FOR
ASCENT WITH THE SHORT WAVE...ISOLATED CONVECTION CERTAINLY SEEMS
POSSIBLE. WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
IN THE FORECAST FOR INLAND AREAS DURING THE AFTERNOON...THEN ACROSS
MUCH OF SOUTHEAST SOUTH CAROLINA IN THE EVENING WHERE CONVERGENCE IN
THE VICINITY OF THE SURFACE TROUGH WILL BE GREATEST. HIGHS ON FRIDAY
WILL BE WELL INTO THE UPPER 80S...BUT CONSIDERABLY COOLER NEAR THE
IMMEDIATE COAST. A MILD NIGHT IS ANTICIPATED...WITH LOWS IN THE MID
TO UPPER 60S.
SATURDAY AND SATURDAY NIGHT...UPPER LEVEL RIDGING WILL AMPLIFY OVER
THE WESTERN GULF OF MEXICO AND SOUTHERN PLAINS STATES...RESULTING IN
A NORTHWEST FLOW ALOFT ACROSS THE REGION. AT THE SURFACE...A LEE
SIDE TROUGH WILL FORM INLAND DURING THE AFTERNOON WHILE A BACKDOOR
COLD FRONT APPROACHES FROM THE NORTH. A SERIES OF SHORT WAVE
DISTURBANCES WILL PUSH THE BACKDOOR FRONT SOUTHWARD AND INTO THE
AREA SATURDAY NIGHT. STRONG FORCING FOR ASCENT AND THE PROXIMITY OF
THE LEE SIDE TROUGH WILL RESULT IN THE FORMATION OF SCATTERED
SHOWERS AND THUNDERSTORMS SATURDAY AFTERNOON INTO EARLY SATURDAY
EVENING. WILL CAP RAIN PROBABILITIES AT 30 PERCENT HOWEVER SINCE
DEEP MOISTURE WILL BE LACKING GIVEN A SOLID DOWNSLOPE FLOW. THERE IS
THE POTENTIAL FOR ISOLATED SEVERE THUNDERSTORMS...AS A 30-35 KT MID
LEVEL JET EMBEDDED WITHIN THE NORTHWEST FLOW ADVANCES ACROSS THE
AREA. IN ADDITION...CONSIDERABLE DESTABILIZATION WILL OCCUR AT THE
SURFACE AS THE DOWNSLOPE FLOW AND COMPRESSIONAL HEATING PUSHES
TEMPERATURES TO AROUND 90 DEGREES AWAY FROM THE IMMEDIATE COAST.
WHILE THE COVERAGE OF CONVECTION WILL DIMINISH BY MID-LATE
EVENING...WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
FOR THE REMAINDER OF SATURDAY NIGHT WITH THE ADVANCING COLD FRONT.
SUNDAY...THE BACKDOOR COLD FRONT WILL CONTINUE TO DROP ACROSS THE
AREA...REACHING SOUTH OF THE ALTAMAHA RIVER BY THE END OF THE DAY.
THE FRONT...AND THEN CONSIDERABLE MOISTURE IN THE NORTH-NORTHEAST
FLOW BEHIND IT...WILL WARRANT KEEPING A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS MENTIONED IN THE FORECAST. TEMPERATURES WILL ONLY
MODERATE SOME...GENERALLY RANGING FROM THE MID 80S NORTH TO THE
UPPER 80S SOUTH.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BUILD FROM THE NORTH IN THE WAKE OF A BACKDOOR
COLD FRONT SUNDAY NIGHT AND MONDAY...THEN AS THE HIGH SHIFTS INTO
THE WESTERN ATLANTIC A RETURN FLOW WILL DEVELOP ON TUESDAY. A COLD
FRONT COULD AFFECT THE AREA DURING THE MID WEEK PERIOD.
THE FORECAST WILL INDICATE A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS DURING NEARLY THE ENTIRE LONG TERM PERIOD. MONDAY WILL
BE THE COOLEST DAY WITH NEAR NORMAL TEMPERATURES EXPECTED...THEN
GRADUAL WARMING WILL OCCUR THROUGH THE MIDDLE OF NEXT WEEK.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
FOG DEVELOPMENT IS AGAIN THE PRIMARY CONCERN THIS MORNING. A VERY
SIMILAR PATTERN EXISTS SINCE 24-HOURS PRIOR WITH THE EXCEPTION OF
A BIT OF CIRRUS OVERSPREADING THE AREA FROM UPSTREAM CONVECTION.
HOWEVER THE CIRRUS APPEARS TO BE DISSIPATING...LEAVING MOSTLY
CLEAR SKIES IN MOST AREAS. THE LATEST HRRR VISIBILITY PLOT SHOWS
THE DENSEST FOG REMAINING JUST INLAND FROM THE TERMINALS SIMILAR
TO WEDNESDAY MORNING. WE ARE KEEPING WITH A PERSISTENCE FORECAST
OVERNIGHT WITH VFR CONDITIONS AT BOTH TERMINALS FOR THE NEXT 24
HRS.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL BE
POSSIBLE DURING THE LATE NIGHT/EARLY MORNING HOURS INTO THE
WEEKEND DUE TO LOW CLOUDS/FOG.
&&
.MARINE...
ATLANTIC HIGH PRESSURE WILL MAINTAIN ITS CONTROL OVER THE MARINE
AREA THROUGH TONIGHT WITH SOUTH TO SOUTHWEST WINDS LESS THAN 15
KT.
ATLANTIC HIGH PRESSURE WILL MAINTAIN A SOUTH/SOUTHWEST FLOW ACROSS
THE WATERS THROUGH FRIDAY. THE FLOW WILL BECOME MORE OFFSHORE
SATURDAY AHEAD OF A BACKDOOR COLD FRONT LIKELY DROPPING INTO THE
WATERS LATE IN THE WEEKEND. WINDS WILL THEN VEER NORTHEAST BEHIND
THE FRONT SUNDAY AND MONDAY. WINDS AND SEAS ARE EXPECTED TO REMAIN
BELOW SMALL CRAFT ADVISORY THRESHOLDS INTO EARLY NEXT
WEEK...ALTHOUGH WINDS COULD SURGE AND SEAS BUILD IN THE NORTHEAST
FLOW BEHIND THE FRONT LATE IN THE WEEKEND INTO EARLY NEXT WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...JRL
SHORT TERM...JRL/JAQ
LONG TERM...JAQ
AVIATION...JRL/JAQ
MARINE...JRL/JAQ
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
421 AM EDT THU MAY 3 2012
.SYNOPSIS...
THE UPPER RIDGE WILL BEGIN TO WEAKEN FRIDAY AND A GRADUAL
INCREASE IN ATMOSPHERIC MOISTURE WILL PROVIDE A SLIGHT CHANCE OF
MAINLY AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS
FRIDAY THROUGH SUNDAY. A SERIES OF UPPER IMPULSES AND SURFACE
BOUNDARIES...ALONG WITH A CONTINUED INCREASE IN MOISTURE...WILL
PROVIDE A CHANCE OF SHOWERS AND THUNDERSTORMS EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
DEVELOPING STRATUS DECK ALONG WITH SOME FOG ACROSS THE EASTERN
MIDLANDS THIS MORNING ACROSS EASTERN GA INTO THE CSRA WILL
CONTINUE TO PROGRESS NORTH/NORTHWESTWARD THROUGH THE EARLY MORNING
HOURS. AS PREVIOUS MORNINGS...EXPECT THE DECK TO DISSIPATE WITH
DAYTIME HEATING BY MID/LATE MORNING. MID/UPPER LEVEL RIDGING
ACROSS THE CAROLINAS WILL CONTINUE TO DOMINATE THE WEATHER THROUGH
THE PERIOD. MODEL TIME SECTIONS SHOW LOW PW VALUES...HIGH LFC
VALUES ALONG WITH WEAK CAPPING THROUGH THE AFTERNOON WITH
RELATIVELY DRY ATMOSPHERE. EXPECT MOSTLY SUNNY SKIES AFTER MORNING
STRATUS ALONG WITH TEMPERATURES SIMILAR TO WEDNESDAY. BOUNDARY
LAYER TEMPERATURES NEARLY THE SAME TODAY...WELL ABOVE NORMAL FOR
EARLY MAY. GUIDANCE AND LOCAL NUMBERS HAVE CONTINUED TO BE A
DEGREE OR TWO TOO COOL THROUGH THE PERIOD AND WILL STAY JUST ABOVE
CONSENSUS. BY TONIGHT...RIDGE STILL HOLDS AND MODELS ONCE AGAIN
SHOW 20 TO 25 KT LOW LEVEL JET ALONG WITH SOME MOISTURE NEAR THE
SURFACE. ANOTHER ROUND OF SOME PATCHY FOG/STRATUS LIKELY TOWARD
MORNING. GUIDANCE AND LOCAL TEMPS VERY CLOSE...BUT WILL STAY WITH
THE TREND OF SLIGHTLY ABOVE GUIDANCE FOR OVERNIGHT MINS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
THE RIDGE WILL BEGIN TO WEAKEN FRIDAY AS UPPER IMPULSES AND AN
AREA OF HIGHER ATMOSPHERIC MOISTURE TO OUR WEST SLOWLY DRIFTS
TOWARDS OUR REGION FROM THE SOUTHWEST/WEST. THE MID/UPPER LEVEL
FLOW ACROSS THE REGION WILL BECOME MORE NORTHWEST THROUGH THE
PERIOD WITH LOWERING HEIGHTS. THIS WILL INCREASE THE CHANCES FOR
AFTERNOON/EVENING CONVECTION ACROSS THE AREA THROUGH THE PERIOD.
WILL FORECAST SLIGHT CHANCE POPS INCREASING TO LOW CHANCE/SLIGHT
CHANCE BY SATURDAY AFTERNOON/SAT NIGHT. AS FOR
TEMPERATURES...GUIDANCE AND LOCAL NUMBERS SHOW A GRADUAL COOL
DOWN FRIDAY INTO SATURDAY FOR AFTERNOON HIGHS. WILL STAY NEAR THE
HIGH SIDE OF GUIDANCE FOR FRIDAY...BUT NEAR GUIDANCE FOR SAT WITH
ADDITIONAL MOISTURE/CLOUDS AND INCREASED CHANCE OF PRECIPITATION.
EXPECT OVERNIGHT LOWS TO REMAIN IN THE MIDDLE 60S. TEMPERATURES
THROUGH THE PERIOD WILL REMAIN MUCH ABOVE NORMAL.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
BOTH ECMWF/GFS FAIRLY SIMILAR IN EVOLUTION OF SYSTEMS THROUGH THE
EXTENDED PERIOD. MODELS GENERALLY INDICATE A SERIES OF UPPER
IMPULSES AND SURFACE BOUNDARIES TO AFFECT OUR REGION...ALONG WITH
A CONTINUED INCREASE IN ATMOSPHERIC MOISTURE THROUGH THE PERIOD.
LATEST GFS ENSEMBLE MOS POPS AND EXPERIMENTAL ECMWF MOS POPS HAVE
TRENDED UP SOMEWHAT FROM PREVIOUS RUNS. THIS IS IN LINE WITH
LATEST HPC GUIDANCE AS WELL...WHICH PROVIDES SLIGHT CHANCE POPS
SUN AND SLIGHT CHANCE/CHANCE MON THRU WED. TEMPERATURES THROUGH
THE PERIOD WILL BE A LITTLE COOLER THAN CURRENT TEMPERATURES.
EXPECT TEMPERATURES IN THE LOWER/MIDDLE 80S FOR HIGHS AND
LOWER/MIDDLE 60S FOR MINS THROUGH THE PERIOD...STILL SLIGHTLY
ABOVE NORMAL.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AS WITH THE PREVIOUS FEW NIGHT...DIURNAL COOLING AND LINGERING
LOW-LEVEL MOISTURE MAY SUPPORT STRATUS AFTER MIDNIGHT LASTING
THROUGH SUNRISE. GFS/NAM BUFKIT TIME SECTIONS SUPPORT THIS ALONG
WITH HRRR GUIDANCE. STRATUS MORE FAVORABLE THAN FOG DUE TO
PERSISTENT LOW-LEVEL JET 20-25 KTS AROUND 1000 FT. FORECASTED A
PERIOD OF IFR STRATUS. THE STRATUS SHOULD MIX OUT LATER IN THE
MORNING BECAUSE OF STRONG HEATING...WITH VFR CONDITIONS THEN LASTING
THROUGH THE DAY.
EXTENDED AVIATION OUTLOOK FRIDAY THROUGH MONDAY...NO SIGNIFICANT
IMPACTS EXPECTED.
&&
.EQUIPMENT...
THE NATIONAL WEATHER SERVICE DOPPLER RADAR IN COLUMBIA SC WILL BE
OUT OF SERVICE THIS WEEK TO UPGRADE TO DUAL POLARIZATION TECHNOLOGY.
PLEASE REFER TO NEIGHBORING RADARS FOR COVERAGE.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...77
NEAR TERM...77
SHORT TERM...77
LONG TERM...77
AVIATION...99
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
207 AM EDT THU MAY 3 2012
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL GRADUALLY SINK SOUTHWARD LATE IN THE
WEEK...AS A TROUGH OF LOW PRESSURE DEVELOPS INLAND. A COLD FRONT
COULD MOVE INTO THE REGION ON SUNDAY...THEN STALL NEAR THE AREA
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE FORECAST AREA WILL LIE UNDER AN AMPLIFYING RIDGE ALOFT OVER
THE SE AND WESTERN PORTION OF THE SUB TROPICAL ATLANTIC RIDGE.
LARGE SCALE SUBSIDENCE AND LITTLE TO NO MOISTURE ABOVE THE
BOUNDARY LAYER SUPPORTS YET ANOTHER NIGHT WITH NO PROSPECTS FOR
RAINFALL...AND OUR DEFICITS GROW FURTHER.
THE MAIN PROBLEM FOR TONIGHT WILL BE THE FORMATION OF FOG AND/OR
STRATUS AND WHETHER OR NOT THE FOG WILL BECOME DENSE ENOUGH FOR A
DENSE FOG ADVISORY. THE FSI VALUES ARE DOWN IN THE SINGLE NUMBERS
AND LOWER TEENS...AND TIME CROSS SECTIONS SHOW CLOSE TO 100
PERCENT RH TRAPPED BENEATH THE NOCTURNAL INVERSION. GEOSTROPHIC
WINDS ARE NO MORE THAN 5 OR 10 KT AND CROSS-OVER TEMPS WILL BE
APPROACHED IF NOT MET IN MANY PLACES. THIS SUGGESTS THAT DENSE FOG
WILL AGAIN DEVELOP. HOWEVER...A SERIOUS CONCERN WOULD BE THE
EXPANDING AREA OF CONVECTIVE CIRRIFORM CLOUDS FROM THE WEST THAT
WILL CONTINUE TO IMPACT WEST AND NW ZONES EARLY TONIGHT. IF THAT
CLOUDINESS HANGS ON THROUGH THE NIGHT IT WOULD LIKELY NEGATE THE
FORMATION OF DENSE FOG. FOR THAT REASON WE HAVE STILL OPTED NOT TO
INCLUDE DENSE FOG WORDING IN THE GRIDDED FORECAST...NOR TO INCLUDE
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. WE WILL OBVIOUSLY NEED
TO CLOSELY EVALUATE THE SITUATION WITH SUBSEQUENT UPDATES THROUGH
THE NIGHT.
FOR NOW WE HAVE MAINTAINED AREAS OF FOG MAINLY NEAR AND WEST-NW
OF A LINE FROM JAMESTOWN TO SUMMERVILLE...CONTINUING TO
JACKSONBORO AND SWITZERLAND IN SC....THEN TO RINCON...FORT STEWART
AND LUDOWICI IN GA. DEVELOPMENT WILL NOT BE UNTIL AFTER 3 OR 4
AM...AS IT/LL TAKE THAT LONG FOR US TO START GETTING CLOSER TO OUR
CROSS-OVER TEMPS. IT IS ALSO THESE AREAS THAT HAVE THE BEST CHANCE
FOR DENSE FOG...BUT ONLY IF CLOUD COVER REMAINS THIN ENOUGH.
VERY SLIGHT WARMING IN THE BOUNDARY LAYER WILL PREVENT TEMPS FROM
FALLING ANY LOWER THAN THE LOWER AND MIDDLE 60S INLAND...AND THE
UPPER 60S AND LOWER 70S ALONG THE COAST. AND THERE IS A SHOT AT
TYING THE RECORD HIGH MINIMUM AT KCHL...WITH THAT MAY 3RD RECORD
OF 72 DEGREES LAST SET IN 2010.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/...
THURSDAY AND THURSDAY NIGHT...DEEP LAYERED RIDGING WILL PREVAIL OVER
THE REGION. STRONG SUBSIDENCE AND A LACK OF MOISTURE WILL KEEP SKIES
MOSTLY CLEAR AND SUPPRESS ANY CONVECTIVE DEVELOPMENT. LOW LEVEL
THICKNESS VALUES CONTINUE TO ADVERTISE UNSEASONABLY WARM
TEMPERATURES...AND WILL INDICATE AFTERNOON HIGHS RANGING FROM THE
UPPER 80S TO LOWER 90S AWAY FROM THE LOCALLY COOLER COAST. NIGHTTIME
LOW TEMPERATURES WILL ALSO BE QUITE MILD...ONLY FALLING INTO THE MID
60S INLAND TO NEAR 70 AT THE COAST.
FRIDAY AND FRIDAY NIGHT...THE DEEP LAYERED RIDGING WILL GRADUALLY
WEAKEN...AS A SHORT WAVE TROUGH SHIFTS ACROSS THE REGION. AT THE
SAME TIME...A SURFACE TROUGH WILL FORM IN THE LEE OF THE
APPALACHIANS AND DESCEND TOWARD THE COAST LATE FRIDAY AND FRIDAY
NIGHT. A TRANSIENT SWATH OF DEEP MOISTURE WILL FOLLOW THE UPPER
LEVEL ENERGY ON FRIDAY...AND CONSIDERING LESS SUBSIDENCE AND A
WEAKER CAPPING INVERSION...THERE WILL BE A SLIGHT CHANCE FOR
SHOWERS AND THUNDERSTORMS ACROSS INLAND AREAS BY FRIDAY AFTERNOON.
WILL CONTINUE SLIGHT CHANCE POPS FOR MAINLY THE NORTHERN PORTIONS
OF THE FORECAST AREA BETWEEN SUNSET AND MIDNIGHT...AS THESE
LOCATIONS WILL BE NEAREST TO THE SHARPENING SURFACE TROUGH AND
SHORTWAVE ENERGY. SOUTHERLY FLOW AND HEIGHTS ALOFT WILL REMAIN
SUFFICIENT TO SUPPORT CONTINUED WARM TEMPERATURES...WITH HIGHS IN
THE UPPER 80S TO AROUND 90 INLAND AND LOWS IN THE MID TO UPPER
60S.
SATURDAY...UPPER LEVEL RIDGING WILL AMPLIFY OVER THE WESTERN GULF
OF MEXICO...RESULTING IN A MORE NORTHWEST COMPONENT TO THE FLOW
ALOFT. A SERIES OF WEAK SHORTWAVES WILL DESCEND INTO THE REGION
ALONG THE PERIPHERY OF THE GULF RIDGE...WHILE A BACKDOOR FRONT
DEVELOPS WITHIN THE APPROACHING INLAND SURFACE TROUGH. THESE
FEATURES WILL SUPPORT A BIT MORE CONVERGENCE AND FORCING FOR
ASCENT...AND WILL INDICATE SLIGHT CHANCE POPS ACROSS MUCH OF THE
FORECAST AREA ACCORDINGLY. DOWNSLOPE FLOW AND PERHAPS SOME PRE
FRONTAL COMPRESSION WILL ALLOW TEMPERATURES TO RISE TO AROUND 90
DEGREES FOR MOST AREAS AWAY FROM THE IMMEDIATE COASTLINE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A BUILDING RIDGE TO THE WEST WILL RESULT IN A NORTHWEST FLOW ALOFT
ACROSS THE REGION LATE IN THE WEEKEND...WHICH SHOULD ENABLE A
BACKDOOR COLD FRONT TO DROP INTO THE AREA. THIS FRONT COULD THEN
STALL NEAR OR JUST SOUTH OF THE AREA INTO EARLY NEXT WEEK AS HIGH
PRESSURE BUILDS FROM THE NORTH. THE HIGH WILL EVENTUALLY SHIFT INTO
THE WESTERN ATLANTIC BY THE MIDDLE OF NEXT WEEK.
THIS OVERALL PATTERN WILL FAVOR INCLUDING A SLIGHT CHANCE OF SHOWERS
AND THUNDERSTORMS IN THE FORECAST THROUGH NEARLY THE ENTIRE LONG
TERM PERIOD...ALTHOUGH MOST OF THE CONVECTION SHOULD GENERALLY OCCUR
DURING THE AFTERNOON/EVENING HOURS DUE TO DIURNAL INFLUENCES.
TEMPERATURES WILL REMAIN WELL ABOVE NORMAL THROUGH THE END OF THE
WEEKEND...THEN MODERATE ONLY A BIT EARLY NEXT WEEK BEHIND THE FRONT.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
FOG DEVELOPMENT IS AGAIN THE PRIMARY CONCERN THIS MORNING. A VERY
SIMILAR PATTERN EXISTS SINCE 24-HOURS PRIOR WITH THE EXCEPTION OF
A BIT OF CIRRUS OVERSPREADING THE AREA FROM UPSTREAM CONVECTION.
HOWEVER THE CIRRUS APPEARS TO BE DISSIPATING...LEAVING MOSTLY
CLEAR SKIES IN MOST AREAS. THE LATEST HRRR VISIBILITY PLOT SHOWS
THE DENSEST FOG REMAINING JUST INLAND FROM THE TERMINALS SIMILAR
TO WEDNESDAY MORNING. WE ARE KEEPING WITH A PERSISTENCE FORECAST
OVERNIGHT WITH VFR CONDITIONS AT BOTH TERMINALS FOR THE NEXT 24
HRS.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS WILL BE
POSSIBLE DURING THE LATE NIGHT/EARLY MORNING HOURS INTO THE
WEEKEND DUE TO LOW CLOUDS/FOG.
&&
.MARINE...
THE SUB TROPICAL RIDGE AXIS WILL EXTEND ACROSS THE COASTAL WATERS
TONIGHT...WITH SE AND SOUTH WINDS EARLY VEERING TO SOUTH AND SW
OVERNIGHT AS LAND BREEZE CIRCULATIONS ATTEMPT TO FORM. WIND SPEEDS
WILL HOLD AT 12 KT OR LESS...WHILE SEAS WILL BE NO HIGHER THAN 2-4
FT /HIGHEST ACROSS THE AMZ374 WATERS/.
ATLANTIC HIGH PRESSURE WILL MAINTAIN A SOUTH/SOUTHWEST FLOW
ACROSS THE WATERS THROUGH FRIDAY. THE FLOW WILL BECOME MORE
OFFSHORE SATURDAY AHEAD OF A BACKDOOR COLD FRONT LIKELY DROPPING
INTO THE WATERS LATE IN THE WEEKEND. WINDS WILL THEN VEER NORTHEAST
BEHIND THE FRONT LATE SUNDAY AND MONDAY. WINDS AND SEAS ARE
EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS INTO
EARLY NEXT WEEK...ALTHOUGH WINDS COULD SURGE AND SEAS BUILD IN THE
NORTHEAST FLOW BEHIND THE FRONT LATE SUNDAY AND MONDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...JRL
SHORT TERM...79
LONG TERM...JAQ/79
AVIATION...JRL
MARINE...79
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
128 AM EDT THU MAY 3 2012
.SYNOPSIS...
THE UPPER RIDGE WILL BEGIN TO WEAKEN FRIDAY AND A GRADUAL
INCREASE IN ATMOSPHERIC MOISTURE WILL PROVIDE A SLIGHT CHANCE OF
MAINLY AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS
FRIDAY THROUGH SUNDAY. A SERIES OF UPPER IMPULSES AND SURFACE
BOUNDARIES...ALONG WITH A CONTINUED INCREASE IN MOISTURE...WILL
PROVIDE A CHANCE OF SHOWERS AND THUNDERSTORMS EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WV LOOP SHOWS RIDGING CONTINUING TO DOMINATE THE WEATHER ACROSS
THE AREA OVERNIGHT. MODEL TIME SECTIONS INDICATE ANOTHER LOW LEVEL
JET FROM 20 TO 25 KTS ALONG WITH SOME SHALLOW LOW LEVEL MOISTURE
THROUGH THE EARLY MORNING HOURS. EXPECT...AS PER THE PAST FEW
MORNINGS TO SEE SOME PREDAWN STRATUS DEVELOPMENT ACROSS THE
REGION. ADJUSTED SKY GRIDS A BIT HIGHER TO ACCOUNT FOR STRATUS
AND SOME CONVECTIVE DEBRIS CLOUDS MOVING IN FROM THE WEST.
HAVE ALSO RAISED OVERNIGHT MINS ABOUT A DEGREE BASED ON CURRENT
OBS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
AN UPPER LEVEL RIDGE WILL REMAIN IN PLACE OVER OUR
FORECAST AREA THROUGH THURSDAY...MAINTAINING FAIR AND WARM
CONDITIONS. THE RIDGE WILL BEGIN TO WEAKEN FRIDAY AS UPPER
IMPULSES AND AN AREA OF HIGHER ATMOSPHERIC MOISTURE TO OUR WEST
SLOWLY DRIFTS TOWARDS OUR REGION. WILL MAINTAIN GOING FORECAST OF
SLIGHT CHANCE POPS FRIDAY AFTERNOON/EARLY EVENING.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
MADE NO SIGNIFICANT CHANGES TO THE ONGOING FORECAST FOR THIS TIME
PERIOD AS WELL. MODELS GENERALLY INDICATE A SERIES OF UPPER
IMPULSES AND SURFACE BOUNDARIES TO AFFECT OUR REGION...ALONG WITH
A CONTINUED INCREASE IN ATMOSPHERIC MOISTURE THROUGH THE PERIOD.
LATEST GFS ENSEMBLE MOS POPS AND EXPERIMENTAL ECMWF MOS POPS HAVE
TRENDED UP SOME. THIS IS IN LINE WITH LATEST HPC GUIDANCE AS
WELL...WHICH PROVIDES SLIGHT CHANCE POPS SAT/SUN AND CHANCE MON
THRU WED...AND CONTINUES TO APPEAR REASONABLE.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS WITH THE PREVIOUS FEW NIGHT...DIURNAL COOLING AND LINGERING
LOW-LEVEL MOISTURE MAY SUPPORT STRATUS AFTER MIDNIGHT LASTING
THROUGH SUNRISE. GFS/NAM BUFKIT TIME SECTIONS SUPPORT THIS ALONG
WITH HRRR GUIDANCE. STRATUS MORE FAVORABLE THAN FOG DUE TO
PERSISTENT LOW-LEVEL JET 20-25 KTS AROUND 1000 FT. FORECASTED A
PERIOD OF IFR STRATUS. THE STRATUS SHOULD MIX OUT LATER IN THE
MORNING BECAUSE OF STRONG HEATING...WITH VFR CONDITIONS THEN LASTING
THROUGH THE DAY.
EXTENDED AVIATION OUTLOOK FRIDAY THROUGH MONDAY...NO SIGNIFICANT
IMPACTS EXPECTED.
&&
.EQUIPMENT...
THE NATIONAL WEATHER SERVICE DOPPLER RADAR IN COLUMBIA SC WILL BE
OUT OF SERVICE THIS WEEK TO UPGRADE TO DUAL POLARIZATION TECHNOLOGY.
PLEASE REFER TO NEIGHBORING RADARS FOR COVERAGE.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...77
NEAR TERM...77
SHORT TERM...
LONG TERM...
AVIATION...99
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS LINCOLN IL
347 AM CDT THU MAY 3 2012
.DISCUSSION...
ISSUED 320 AM CDT THU MAY 3 2012
WEAK RIDGING OVER THE EASTERN HALF OF THE CONUS THIS
MORNING...AND SOUTHWESTERLY FLOW OVER MUCH OF THE SOUTHERN PLAINS
AND INTO THE MIDWEST KEEPING A STRING OF CONVECTIVE WAVES MOVING
INTO THE REGION. THIS MORNING...ANOTHER WAVE OVER THE CENTRAL
MISSOURI RIVER VALLEY AND WRN IA EXPECTED TO MOVE INTO THE UPPER
MIDWEST LATER TODAY. FIRST ISSUE FOR THE FORECAST IS THE TIMING OF
THE WAVE...AND THE PRECIP INTO THE CURRENT AIRMASS FOR CENTRAL
ILLINOIS...WHICH BY THE 00Z SOUNDING IS RELATIVELY DRY. MODELS
HAVING A BIT OF AN ISSUE WORKING OUT THE CURRENT CONVECTION...MUCH
LESS ITS PROGRESSION. BOUNDARY SINKING THROUGH TONIGHT AND
INCREASING THE POPS THROUGH TONIGHT AND INTO TOMORROW MORNING.
SHOWERS AND TS CONTINUE THROUGH THE FIRST PORTION OF THE WEEKEND.
CONCERNS STILL FOR WHERE THE BREAKS IN THE PRECIP MAY BE...BEFORE
THE LARGER SCALE TROF OVER THE NWRN CONUS BEGINS TO MOVE OUT...AND
THE SFC LOW DRAGS THROUGH THE MIDWEST MON/MON NIGHT...LEAVING A
BRIEF RESPITE FROM THE RAINFALL IN THE MIDDLE OF THE NEXT WORK
WEEK.
SHORT TERM...TODAY AND TOMORROW...
WARM AND MUGGY CONDITIONS AS SOUTHERLY WINDS USHER WARM AIR INTO
THE MIDWEST. A BIT OF A QUESTION MARK REMAINS THE HIGH TEMPS NW OF
THE ILLINOIS RIVER VALLEY...WHERE CLOUD COVER IS ENHANCED BY DYING
MCS PASSING TO THE NW THIS MORNING. CLOUD COVER/COLD POOL LIKELY TO
INHIBIT THE WARM UP A BIT...THOUGH THE SOUTHERLY WINDS ARE
COUNTERING. MUCH SUNNIER TO THE SOUTH AND EAST OF THE INTERSTATE
55 CORRIDOR...AND TEMPS SOARING INTO THE MID TO UPPER 80S...850MB
TEMPS IN THE 17-18C RANGE...AND MIXING DOWN SOME 20-25MPH GUSTS.
ISSUE FOR THE CURRENT POPS...WHICH THE HRRR IS THE ONLY MODEL TO
REALLY DEPICT WELL...ALBEIT ABOUT 2 HOURS BEHIND AND A LITTLE
UNDERDONE...IS THE ARRIVAL AND POTENTIAL IMPACT TO AREAS IN THE
NRN TIER OF THE STATE AND CWA LATER THIS AFTERNOON. HAVE SLIGHTLY
ADJUSTED SOME HIGHER CHANCE POPS FOR THIS TREND AND MAY NEED TO
KEEP A CLOSE LOOK FOR THIS AFTERNOON IN MORE OF THE HIGH RES
SOLUTIONS. THIS EVENING AND TONIGHT...PRECIP CHANCES INCREASE AS
THE UPPER RIDGE STARTS TO BREAK DOWN AND THE CONVECTION TO THE NW
PUSHES INTO THE FA. MODELS CONTINUE TO PUSH SMALL REINFORCING
SHORTWAVES TO KEEP THE REGION IN PRECIP THROUGH MUCH OF FRIDAY OFF
AND ON.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
POSSIBLE BREAK FOR PART OF SATURDAY IN THE SHOWERY PRECIP...AT
LEAST BEING HINTED IN THE MODELS AS MORE DETAIL WORKS IN...WITH
THE LARGER SCALE SYSTEM PUSHING IN SAT NIGHT WITH THE UPPER LOW ON
THE MOVE ACROSS THE NRN PLAINS. STRONGER SFC LOW ACROSS THE NRN
BOUNDARY OF THE CONUS...DEEP TROF/FRONTAL BOUNDARY TO WEAKER
SOUTHERN SFC LOW PUSHING A BOUNDARY THROUGH THE MIDWEST SUN/MON
AND A RETURN OF THE POPS AGAIN THROUGH THE END OF THE
FORECAST...WITH BEST CHANCES SUN NIGHT THROUGH MON NIGHT FOR MORE
EXTENSIVE RAIN AS THE SFC LOW IS SLIGHTLY SLUGGISH TO MOVE OUT.
ECMWF IS A BIT SLOWER THAN THE GFS...BUT NOT TOO FAR OFF
ALTOGETHER. A SMALL BREAK IN THE HEAT WITH THE SYSTEM AS HIGHS FOR
MON/TUES A BIT LOWER WITH THE MID LEVEL TROF GETTING SOME COOLER
AIR OVHD BEHIND THE RIDGE. COOLER TEMPS CONTINUE THROUGH MIDWEEK
AS THE UPPER TROF SLOWS AS WELL...THOUGH SFC STARTS TO DRY OUT A
BIT WED NIGHT.
HJS
&&
.AVIATION...
ISSUED 1125 PM CDT WED MAY 2 2012
FRONTAL BOUNDARY OUT ALONG THE MISSOURI RIVER HAS SPARKED A LARGE
AREA OF CONVECTION THIS EVENING WITH MOST OF THE ACTIVITY TRACKING
MORE TO THE NORTHEAST WHICH WOULD KEEP THE PRECIP AWAY FROM THE
TAF SITES THRU DAWN THURSDAY. A FEW OF THE MODELS CONTINUE TO
SUGGEST SOME LOW VFR/HIGH END MVFR CIGS MAY PUSH INTO WESTERN
IL BY DAWN THURSDAY...HOWEVER...SURFACE OBS AND SATELLITE DATA
WERE NOT INDICATING MUCH IN THE WAY OF LOW CLOUDS TO OUR SW WHERE
IT SHOULD AT THIS TIME ACCORDING TO THE MODEL. WILL CONTINUE FROM
THE PREVIOUS FORECAST IN HOLDING ON TO A SCATTERED DECK AT 2000-2500
FEET AT PIA AND SPI. OTHERWISE...SOME SCATTERED CU DEVELOPING
TOMORROW ALONG WITH A GUSTY SOUTH WIND BY AFTN WITH A FEW GUSTS
AROUND 25 KTS. VAD WIND PROFILES CURRENTLY SHOWING 30-35 KTS AT
1500 FEET WITH MODELS SUGGESTING BORDERLINE LOW LEVEL WIND SHEAR
CRITERIA...ESP ACRS THE WEST IN THE 06Z-11Z TIME FRAME.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
325 AM CDT THU MAY 3 2012
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE....
HAVE MADE SOME SIGNIFICANT ADJUSTMENTS TO POP/WX GRIDS INTO THE
OVERNIGHT HOURS BASED ON ANALYSIS/CONVECTIVE TRENDS UPSTREAM.
WARM FRONT WHICH LIFTED NORTH OF THE FORECAST AREA EARLIER THIS
MORNING HAS BECOME SOMEWHAT ILL-DEFINED ACROSS WISCONSIN AND LOWER
MICHIGAN THIS EVENING...WHILE A SECONDARY TROUGH/WARM FRONT WAS
NOTED FROM NORTHERN MISSOURI INTO CENTRAL IL/IND ENHANCED FROM
COMBINATION OF RETREATING CONVECTIVE OUTFLOW FROM MORNING MCS AND
DIFFERENTIAL HEATING FROM CLOUD COVER EARLIER IN THE DAY. THIS AREA
HAD BECOME RELATIVELY CLOUD-FREE LATE THIS AFTERNOON IN THE WAKE OF
THE SHORT-WAVE TROUGH AXIS WHICH HAS MOVED EAST OF THE AREA PER
WATER VAPOR IMAGERY AND PROFILER WINDS AT WOLCOTT IN. WHILE AIR MASS
IS WARM AND RATHER HUMID...WITH TEMPS STILL IN MID 70S AND DEW
POINTS IN THE MID-UPPER 60S ACROSS SOUTHERN CWA...00Z RAOBS FROM DVN
AND ILX DEPICT STRONG CAPPING INVERSION EXISTS FOR SFC/NEAR SFC
BASED CONVECTION. IN ADDITION...AIR MASS TO THE WEST ACROSS IOWA HAS
REMAINED STABILIZED WITH EXTENSIVE STRATUS DECK THROUGH THE
AFTERNOON AND HAS PREVENTED NEAR SFC BASED CONVECTION FROM
DEVELOPING SAVE FAR SOUTHERN MN/EASTERN NEBRASKA AREAS FARTHER NORTH
AND WEST.
CONVECTION-ALLOWING GUIDANCE INCLUDING WRF-NMM AND HRRR/RAP HAVE
BEEN INDICATING SIGNIFICANT CONVECTIVE DEVELOPMENT ACROSS EASTERN
IOWA INTO SOUTHWEST WISCONSIN DURING THE AFTERNOON AND EVENING
HOURS...BUT BASED ON THERMODYNAMIC PROFILES AND PRE-SUNSET VIS
SATELLITE TRENDS...EARLIER RUNS APPEAR TO HAVE OVER-FORECAST EXTENT
OF DEVELOPMENT. SOME FACTORS DO SUPPORT THE POTENTIAL FOR INCREASING
SHRA/TSRA THREAT THIS EVENING...MAINLY WITH BETTER MOIST ASCENT
DEVELOPING ABOVE STABLE BOUNDARY LAYER AS H9-H8 LOW LEVEL JET
INCREASES TO 35-40 KT AND MID-LEVEL SPEED MAX APPROACHES FROM THE
SOUTHWEST WITHIN AND AREA OF VERY STEEP MID-LEVEL LAPSE RATES WITH
EML NOTED IN OAX/DVN SOUNDINGS. AN ISOLATED AREA OF SHOWERS/WEAK
TSRA HAVE DEVELOPED ALONG A CONVERGENCE ZONE ACROSS FAR EASTERN IA
FROM NEAR MUSCATINE TO JUST WEST OF SAVANNA IL...LIKELY A
REPRESENTATION OF WHAT THE WRF-NMM AND HRRR/RAP WERE TRYING TO
DEPICT BUT ON A MORE LIMITED SCALE. TREND FROM THESE MODELS WOULD
SUGGEST THIS ACTIVITY WILL LIKELY FOCUS MORE ACROSS OUR FAR
NORTHWEST/NORTHERN CWA INTO THE OVERNIGHT HOURS...AND PERHAPS MORE
SO OVER SOUTHERN WI WHERE BETTER DEEP MOIST CONVERGENCE IS NOTED IN
ASSOCIATION WITH SYNOPTIC H9-H8 WARM FRONT. BASED ON ALL OF THIS...
HAVE GENERALLY LOWERED/REMOVED POPS ACROSS THE SOUTHERN CWA
OVERNIGHT. THE RECENT HRRR RUNS WOULD EVEN SUGGEST WE MAY BE DRY
ACROSS THE NORTH EXCEPT FOR RIGHT ALONG THE WI/IL LINE AFTER
MIDNIGHT...THOUGH MY CONFIDENCE IS NOT HIGH ENOUGH TO PULL POPS WITH
UNCERTAIN EVOLUTION OF CONVECTION CURRENTLY FARTHER UPSTREAM. THUS
HAVE GENERALLY LEFT HIGHER POPS GENERALLY NORTH OF I-88 ACROSS
NORTHERN IL...WITH FAR SOUTHERN COUNTIES DRY. HRRR ALSO INDICATES
MCS DEVELOPMENT ACROSS NEBRASKA...WHERE KS/NEBR ACTIVITY IS
CURRENTLY JUST GETTING GOING. LATEST GUIDANCE INDICATES THIS WOULD
NOT ARRIVE UNTIL AFTER 12Z WEDNESDAY IN DECAYING FORM.
RATZER
//PREV DISCUSSION...
329 PM CDT
MAIN FORECAST CHALLENGES REVOLVE AROUND SHOWER/THUNDERSTORM
CHANCES OVER THE NEXT SEVERAL DAYS WITH THE SEVERE POTENTIAL
REMAINING FOR TONIGHT AS WELL AS THURSDAY NIGHT...WITH HIGH
TEMPERATURES BEING DICTATED BY REMNANT PRECIP/CLOUD COVER THROUGH
EACH DAY.
LATEST RADAR IMAGERY DEPICTING AREA OF SHOWERS AND THUNDERSTORMS
WHICH SLOWLY PROGRESSED THROUGH PORTIONS OF THE CWA...CONTINUING
TO DIMINISH THIS AFTERNOON WITH MOST AREAS CURRENTLY DRY. EXPECT
THESE RELATIVELY DRY CONDITIONS TO REMAIN FOR A PORTION OF THIS
AFTERNOON INTO EARLY EVENING...OUTSIDE OF SOME ISOLATED/BRIEF
SHOWERS AND THUNDERSTORMS POSSIBLY DEVELOPING ALONG LINGERING
OUTFLOW BOUNDARIES WHICH SEVERAL ARE CURRENTLY SITUATED OVER THE
CWA. ANY SHOWERS/THUNDERSTORMS WHICH DO DEVELOP THIS AFTERNOON
SHOULD NOT BECOME SEVERE AS INSTABILITY IS STILL LACKING DUE TO A
RECOVERING ENVIRONMENT AND STRONGER WESTERLIES REMAINING TO THE
NORTHWEST.
STRONG SOUTHERLY FLOW OUT AHEAD OF A TROUGH OF LOW PRESSURE WELL
TO THE WEST OVER THE CENTRAL PLAINS WILL HELP FOR THE ENVIRONMENT
OVER THE CWA TO TO SLIGHTLY RECOVER THIS EVENING THROUGH EARLY
THURSDAY MORNING BRINGING LOW TO MID 60S DEWPOINT AIR BACK NORTH
ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS SHOULD HELP
TO INCREASE OVERALL INSTABILITY OVER THE CWA THIS EVENING WHICH
COULD PROVIDE A SETUP FOR ANOTHER ROUND OF THUNDERSTORMS TO RACE
ACROSS THE CWA. MODEL GUIDANCE CONTINUES TO BE ALL OVER THE PLACE
IN REGARDS TO ENVIRONMENTAL DETAILS DUE TO MESOCALE FEATURES WHICH
CONTINUE TO DISRUPT THE LARGE SCALE PATTERN. THIS IS TRANSLATING
TO A LACK OF CONFIDENCE IN MODEL GENERATED PRECIP IN THE NEAR TERM
AS WELL AS FOR THE NEXT SEVERAL DAYS. DESPITE THIS LACK OF
CONFIDENCE IN NUMERICAL GUIDANCE...CAN STILL MAKE OUT SOME OF AREA
FOCUS FOR THUNDERSTORM DEVELOPMENT. ENVIRONMENT SHOULD CONTINUE TO
RECOVER ACROSS THE ENTIRE REGION FROM THE CENTRAL PLAINS BACK EAST
TO THE GREAT LAKES REGION WITH DEEP MOISTURE BACK ON THE RISE.
MAIN INSTABILITY AXIS IS SITUATED FROM WESTERN IOWA EAST INTO
SOUTHERN WISCONSIN...WITH INSTABILITY ANTICIPATED TO CONTINUE TO
INCREASE OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THE EXTENT OF THIS INCREASE OVER THE CWA IS STILL IN
QUESTION...WHICH WILL PLAY A FACTOR IN THUNDERSTORM INTENSITY
TONIGHT. A SUBTLE MID LEVEL IMPULSE CURRENTLY OBSERVED EJECTING
ACROSS THE CENTRAL PLAINS COINCIDING WITH AN INCREASING LLJ SHOULD
INTERACT WITH A FRONTAL BOUNDARY OVER THE CENTRAL PLAINS LATER
THIS EVENING AND HELP FOR THE DEVELOPMENT OF THUNDERSTORMS ACROSS
IOWA. INSTABILITY SHOULD BE MORE THAN ENOUGH TO GET ROBUST
DEVELOPMENT WITH STEERING FLOW/LOW LEVEL SHEAR HELPING TO SHIFT
THIS THUNDERSTORM DEVELOPMENT EAST. A GROWING COMPLEX SHOULD WORK
ITS WAY EAST MAINLY AFFECTING THE NORTHERN HALF OF THE CWA LATER
TONIGHT INTO EARLY THURSDAY MORNING. OVERALL INSTABILITY IS STILL
IN QUESTION ACROSS THE CWA...BUT WITH DEEP MOISTURE NOT. IF
INSTABILITY INCREASES...A HAIL AND WIND THREAT WILL BE POSSIBLE
TONIGHT. IF NOT...AM STILL CONCERNED ABOUT THE POTENTIAL FOR VERY
RAIN EFFICIENT THUNDERSTORMS AS A VERY WARM AND JUICY AIRMASS WILL
BE IN PLACE. WITH ANY MCS PASSAGE TONIGHT...COULD ENVISION FURTHER
UPSCALE DEVELOPMENT AS A STRONG LLJ INTERACTS WITH ANY LINGERING
BOUNDARIES. THIS COULD PROVIDE A SETUP FOR TRAINING OF
THUNDERSTORMS AND HEAVY RAINFALL INTO THURSDAY MORNING.
ADVECTION OF A MUCH WARMER AIRMASS WILL CONTINUE ON THURSDAY WITH
WELL ABOVE NORMAL TEMPERATURES FORECAST. HAVE MAINTAINED MID AND
UPPER 80S FOR THE SOUTHERN HALF OF THE CWA BUT HAVE LOWERED TEMPS
TO AROUND 80 FOR THE NORTHERN HALF DUE TO POSSIBLE LINGERING
CONVECTION AND CLOUD COVER THURSDAY MORNING. ONGOING CONVECTION
DURING THE DAY THURSDAY WILL DEFINITELY BE KEY WITH FURTHER
DEVELOPMENT FOR THE REMAINDER OF THURSDAY INTO FRIDAY
MORNING...WHICH ONCE AGAIN SEEMS PROBABLE. ADVECTION OF A WARM AND
VERY MOIST AIR WILL CONTINUE AIDING IN INSTABILITY WITH THE SETUP
WHICH IS POSSIBLE TONIGHT LIKELY OCCURRING OVER NORTHERN ILLINOIS
ON THURSDAY. THIS WILL BRING ANOTHER ROUND OF THUNDERSTORMS WHICH
WILL BE CAPABLE OF PRODUCING LARGE HAIL/DAMAGING WINDS AND HAIL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* CHANCE FOR MVFR VIS IN BR DURING THE EARLY MORNING HOURS.
* SELY WINDS VEERING SWLY IN THE MORNING THAN THEN BECOMING GUSTY
IN THE AFTERNOON.
* CHANCE OF SHRA/TSRA TOMORROW EVENING.
KREIN
//DISCUSSION...UPDATED 06Z...
EXPECT THAT THE REMAINDER OF THE NIGHT SHOULD BE RELATIVELY QUIET
AT THE TERMINALS. THE LATEST RADAR IMAGERY INDICATES THAT ALL OF
THE ONGOING PCPN IS WELL TO THE NORTH IN WISCONSIN. WHILE THERE IS
SOME NEW DEVELOPMENT OVER FAR NERN IOWA AND SWRN WI...FEEL THAT
THE LOCAL TERMINALS WILL REMAIN DRY. THE ONLY WX IMPACT AT THE
TERMINALS TONIGHT WILL LIKELY BE REDUCED VISIBILITY DURG THE EARLY
MORNING HOURS. WITH THE ABSENCE OF ANY SGFNT CLOUDCOVER AND WITH
LIGHT WINDS AND A MOIST AIRMASS AT THE SFC...EXPECT THAT VIS WILL
DROP TO 3-4SM.
THE NEXT CHANCE FOR PCPN WILL COME TOMORROW EVENING.
HOWEVER...CONFIDENCE REMAINS LOW IN TIMING AND COVERAGE. THE MAIN
FEATURE OF CONCERN IS A VERY WEAK COLD FRONT DROPPING OUT OF THE
UPPER MISSISSIPPI VALLEY. THIS BOUNDARY WILL BE THE PRIMARY FOCUS
FOR PCPN ACTIVITY. HOWEVER...SINCE IT IS SUCH A DIFFUSE
BOUNDARY...WILL ONLY CARRY MENTION OF POSSIBLE TSRA IN A PROB30 GROUP.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN VIS TREND OVERNIGHT AND CHANCES FOR MVFR
DURG THE EARLY MORNING HOURS.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* LOW CONFIDENCE IN PCPN FORECAST TOMORROW EVENING.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH PERIODIC
CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE FRIDAY
INTO THE WEEKEND.
KJB
&&
.MARINE...
325 AM CDT
A COLD FRONT EXTENDING FROM THE UPPER MISSISSIPPI VALLEY
THROUGH THE CENTRAL PLAINS WILL GRADUALLY SAG SOUTHWARD DOWN THE
LENGTH OF LAKE MICHIGAN LATER THIS MORNING. WINDS OVER THE LAKE
WILL GRADUALLY SHIFT FROM GENERALLY SOUTHERLY TO GENERALLY
NORTHERLY FOLLOWING THE FRONTAL PASSAGE. WINDS SHOULD THEN SETTLE
INTO NORTHEASTERLY TO EASTERLY THROUGH THE WEEKEND AND INTO EARLY
NEXT WEEK AS THE FRONT REMAINS STALLED OUT OVER THE OHIO VALLEY AND
HIGH PRESSURE REMAINS SITUATED OVER EASTERN CANADA.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
119 AM CDT THU MAY 3 2012
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE....
HAVE MADE SOME SIGNIFICANT ADJUSTMENTS TO POP/WX GRIDS INTO THE
OVERNIGHT HOURS BASED ON ANALYSIS/CONVECTIVE TRENDS UPSTREAM.
WARM FRONT WHICH LIFTED NORTH OF THE FORECAST AREA EARLIER THIS
MORNING HAS BECOME SOMEWHAT ILL-DEFINED ACROSS WISCONSIN AND LOWER
MICHIGAN THIS EVENING...WHILE A SECONDARY TROUGH/WARM FRONT WAS
NOTED FROM NORTHERN MISSOURI INTO CENTRAL IL/IND ENHANCED FROM
COMBINATION OF RETREATING CONVECTIVE OUTFLOW FROM MORNING MCS AND
DIFFERENTIAL HEATING FROM CLOUD COVER EARLIER IN THE DAY. THIS AREA
HAD BECOME RELATIVELY CLOUD-FREE LATE THIS AFTERNOON IN THE WAKE OF
THE SHORT-WAVE TROUGH AXIS WHICH HAS MOVED EAST OF THE AREA PER
WATER VAPOR IMAGERY AND PROFILER WINDS AT WOLCOTT IN. WHILE AIR MASS
IS WARM AND RATHER HUMID...WITH TEMPS STILL IN MID 70S AND DEW
POINTS IN THE MID-UPPER 60S ACROSS SOUTHERN CWA...00Z RAOBS FROM DVN
AND ILX DEPICT STRONG CAPPING INVERSION EXISTS FOR SFC/NEAR SFC
BASED CONVECTION. IN ADDITION...AIR MASS TO THE WEST ACROSS IOWA HAS
REMAINED STABILIZED WITH EXTENSIVE STRATUS DECK THROUGH THE
AFTERNOON AND HAS PREVENTED NEAR SFC BASED CONVECTION FROM
DEVELOPING SAVE FAR SOUTHERN MN/EASTERN NEBRASKA AREAS FARTHER NORTH
AND WEST.
CONVECTION-ALLOWING GUIDANCE INCLUDING WRF-NMM AND HRRR/RAP HAVE
BEEN INDICATING SIGNIFICANT CONVECTIVE DEVELOPMENT ACROSS EASTERN
IOWA INTO SOUTHWEST WISCONSIN DURING THE AFTERNOON AND EVENING
HOURS...BUT BASED ON THERMODYNAMIC PROFILES AND PRE-SUNSET VIS
SATELLITE TRENDS...EARLIER RUNS APPEAR TO HAVE OVER-FORECAST EXTENT
OF DEVELOPMENT. SOME FACTORS DO SUPPORT THE POTENTIAL FOR INCREASING
SHRA/TSRA THREAT THIS EVENING...MAINLY WITH BETTER MOIST ASCENT
DEVELOPING ABOVE STABLE BOUNDARY LAYER AS H9-H8 LOW LEVEL JET
INCREASES TO 35-40 KT AND MID-LEVEL SPEED MAX APPROACHES FROM THE
SOUTHWEST WITHIN AND AREA OF VERY STEEP MID-LEVEL LAPSE RATES WITH
EML NOTED IN OAX/DVN SOUNDINGS. AN ISOLATED AREA OF SHOWERS/WEAK
TSRA HAVE DEVELOPED ALONG A CONVERGENCE ZONE ACROSS FAR EASTERN IA
FROM NEAR MUSCATINE TO JUST WEST OF SAVANNA IL...LIKELY A
REPRESENTATION OF WHAT THE WRF-NMM AND HRRR/RAP WERE TRYING TO
DEPICT BUT ON A MORE LIMITED SCALE. TREND FROM THESE MODELS WOULD
SUGGEST THIS ACTIVITY WILL LIKELY FOCUS MORE ACROSS OUR FAR
NORTHWEST/NORTHERN CWA INTO THE OVERNIGHT HOURS...AND PERHAPS MORE
SO OVER SOUTHERN WI WHERE BETTER DEEP MOIST CONVERGENCE IS NOTED IN
ASSOCIATION WITH SYNOPTIC H9-H8 WARM FRONT. BASED ON ALL OF THIS...
HAVE GENERALLY LOWERED/REMOVED POPS ACROSS THE SOUTHERN CWA
OVERNIGHT. THE RECENT HRRR RUNS WOULD EVEN SUGGEST WE MAY BE DRY
ACROSS THE NORTH EXCEPT FOR RIGHT ALONG THE WI/IL LINE AFTER
MIDNIGHT...THOUGH MY CONFIDENCE IS NOT HIGH ENOUGH TO PULL POPS WITH
UNCERTAIN EVOLUTION OF CONVECTION CURRENTLY FARTHER UPSTREAM. THUS
HAVE GENERALLY LEFT HIGHER POPS GENERALLY NORTH OF I-88 ACROSS
NORTHERN IL...WITH FAR SOUTHERN COUNTIES DRY. HRRR ALSO INDICATES
MCS DEVELOPMENT ACROSS NEBRASKA...WHERE KS/NEBR ACTIVITY IS
CURRENTLY JUST GETTING GOING. LATEST GUIDANCE INDICATES THIS WOULD
NOT ARRIVE UNTIL AFTER 12Z WEDNESDAY IN DECAYING FORM.
RATZER
//PREV DISCUSSION...
329 PM CDT
MAIN FORECAST CHALLENGES REVOLVE AROUND SHOWER/THUNDERSTORM
CHANCES OVER THE NEXT SEVERAL DAYS WITH THE SEVERE POTENTIAL
REMAINING FOR TONIGHT AS WELL AS THURSDAY NIGHT...WITH HIGH
TEMPERATURES BEING DICTATED BY REMNANT PRECIP/CLOUD COVER THROUGH
EACH DAY.
LATEST RADAR IMAGERY DEPICTING AREA OF SHOWERS AND THUNDERSTORMS
WHICH SLOWLY PROGRESSED THROUGH PORTIONS OF THE CWA...CONTINUING
TO DIMINISH THIS AFTERNOON WITH MOST AREAS CURRENTLY DRY. EXPECT
THESE RELATIVELY DRY CONDITIONS TO REMAIN FOR A PORTION OF THIS
AFTERNOON INTO EARLY EVENING...OUTSIDE OF SOME ISOLATED/BRIEF
SHOWERS AND THUNDERSTORMS POSSIBLY DEVELOPING ALONG LINGERING
OUTFLOW BOUNDARIES WHICH SEVERAL ARE CURRENTLY SITUATED OVER THE
CWA. ANY SHOWERS/THUNDERSTORMS WHICH DO DEVELOP THIS AFTERNOON
SHOULD NOT BECOME SEVERE AS INSTABILITY IS STILL LACKING DUE TO A
RECOVERING ENVIRONMENT AND STRONGER WESTERLIES REMAINING TO THE
NORTHWEST.
STRONG SOUTHERLY FLOW OUT AHEAD OF A TROUGH OF LOW PRESSURE WELL
TO THE WEST OVER THE CENTRAL PLAINS WILL HELP FOR THE ENVIRONMENT
OVER THE CWA TO TO SLIGHTLY RECOVER THIS EVENING THROUGH EARLY
THURSDAY MORNING BRINGING LOW TO MID 60S DEWPOINT AIR BACK NORTH
ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS SHOULD HELP
TO INCREASE OVERALL INSTABILITY OVER THE CWA THIS EVENING WHICH
COULD PROVIDE A SETUP FOR ANOTHER ROUND OF THUNDERSTORMS TO RACE
ACROSS THE CWA. MODEL GUIDANCE CONTINUES TO BE ALL OVER THE PLACE
IN REGARDS TO ENVIRONMENTAL DETAILS DUE TO MESOCALE FEATURES WHICH
CONTINUE TO DISRUPT THE LARGE SCALE PATTERN. THIS IS TRANSLATING
TO A LACK OF CONFIDENCE IN MODEL GENERATED PRECIP IN THE NEAR TERM
AS WELL AS FOR THE NEXT SEVERAL DAYS. DESPITE THIS LACK OF
CONFIDENCE IN NUMERICAL GUIDANCE...CAN STILL MAKE OUT SOME OF AREA
FOCUS FOR THUNDERSTORM DEVELOPMENT. ENVIRONMENT SHOULD CONTINUE TO
RECOVER ACROSS THE ENTIRE REGION FROM THE CENTRAL PLAINS BACK EAST
TO THE GREAT LAKES REGION WITH DEEP MOISTURE BACK ON THE RISE.
MAIN INSTABILITY AXIS IS SITUATED FROM WESTERN IOWA EAST INTO
SOUTHERN WISCONSIN...WITH INSTABILITY ANTICIPATED TO CONTINUE TO
INCREASE OVER NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THE EXTENT OF THIS INCREASE OVER THE CWA IS STILL IN
QUESTION...WHICH WILL PLAY A FACTOR IN THUNDERSTORM INTENSITY
TONIGHT. A SUBTLE MID LEVEL IMPULSE CURRENTLY OBSERVED EJECTING
ACROSS THE CENTRAL PLAINS COINCIDING WITH AN INCREASING LLJ SHOULD
INTERACT WITH A FRONTAL BOUNDARY OVER THE CENTRAL PLAINS LATER
THIS EVENING AND HELP FOR THE DEVELOPMENT OF THUNDERSTORMS ACROSS
IOWA. INSTABILITY SHOULD BE MORE THAN ENOUGH TO GET ROBUST
DEVELOPMENT WITH STEERING FLOW/LOW LEVEL SHEAR HELPING TO SHIFT
THIS THUNDERSTORM DEVELOPMENT EAST. A GROWING COMPLEX SHOULD WORK
ITS WAY EAST MAINLY AFFECTING THE NORTHERN HALF OF THE CWA LATER
TONIGHT INTO EARLY THURSDAY MORNING. OVERALL INSTABILITY IS STILL
IN QUESTION ACROSS THE CWA...BUT WITH DEEP MOISTURE NOT. IF
INSTABILITY INCREASES...A HAIL AND WIND THREAT WILL BE POSSIBLE
TONIGHT. IF NOT...AM STILL CONCERNED ABOUT THE POTENTIAL FOR VERY
RAIN EFFICIENT THUNDERSTORMS AS A VERY WARM AND JUICY AIRMASS WILL
BE IN PLACE. WITH ANY MCS PASSAGE TONIGHT...COULD ENVISION FURTHER
UPSCALE DEVELOPMENT AS A STRONG LLJ INTERACTS WITH ANY LINGERING
BOUNDARIES. THIS COULD PROVIDE A SETUP FOR TRAINING OF
THUNDERSTORMS AND HEAVY RAINFALL INTO THURSDAY MORNING.
ADVECTION OF A MUCH WARMER AIRMASS WILL CONTINUE ON THURSDAY WITH
WELL ABOVE NORMAL TEMPERATURES FORECAST. HAVE MAINTAINED MID AND
UPPER 80S FOR THE SOUTHERN HALF OF THE CWA BUT HAVE LOWERED TEMPS
TO AROUND 80 FOR THE NORTHERN HALF DUE TO POSSIBLE LINGERING
CONVECTION AND CLOUD COVER THURSDAY MORNING. ONGOING CONVECTION
DURING THE DAY THURSDAY WILL DEFINITELY BE KEY WITH FURTHER
DEVELOPMENT FOR THE REMAINDER OF THURSDAY INTO FRIDAY
MORNING...WHICH ONCE AGAIN SEEMS PROBABLE. ADVECTION OF A WARM AND
VERY MOIST AIR WILL CONTINUE AIDING IN INSTABILITY WITH THE SETUP
WHICH IS POSSIBLE TONIGHT LIKELY OCCURRING OVER NORTHERN ILLINOIS
ON THURSDAY. THIS WILL BRING ANOTHER ROUND OF THUNDERSTORMS WHICH
WILL BE CAPABLE OF PRODUCING LARGE HAIL/DAMAGING WINDS AND HAIL.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* CHANCE FOR MVFR VIS IN BR DURING THE EARLY MORNING HOURS.
* SELY WINDS VEERING SWLY IN THE MORNING THAN THEN BECOMING GUSTY
IN THE AFTERNOON.
* CHANCE OF SHRA/TSRA TOMORROW EVENING.
KREIN
//DISCUSSION...UPDATED 06Z...
EXPECT THAT THE REMAINDER OF THE NIGHT SHOULD BE RELATIVELY QUIET
AT THE TERMINALS. THE LATEST RADAR IMAGERY INDICATES THAT ALL OF
THE ONGOING PCPN IS WELL TO THE NORTH IN WISCONSIN. WHILE THERE IS
SOME NEW DEVELOPMENT OVER FAR NERN IOWA AND SWRN WI...FEEL THAT
THE LOCAL TERMINALS WILL REMAIN DRY. THE ONLY WX IMPACT AT THE
TERMINALS TONIGHT WILL LIKELY BE REDUCED VISIBILITY DURG THE EARLY
MORNING HOURS. WITH THE ABSENCE OF ANY SGFNT CLOUDCOVER AND WITH
LIGHT WINDS AND A MOIST AIRMASS AT THE SFC...EXPECT THAT VIS WILL
DROP TO 3-4SM.
THE NEXT CHANCE FOR PCPN WILL COME TOMORROW EVENING.
HOWEVER...CONFIDENCE REMAINS LOW IN TIMING AND COVERAGE. THE MAIN
FEATURE OF CONCERN IS A VERY WEAK COLD FRONT DROPPING OUT OF THE
UPPER MISSISSIPPI VALLEY. THIS BOUNDARY WILL BE THE PRIMARY FOCUS
FOR PCPN ACTIVITY. HOWEVER...SINCE IT IS SUCH A DIFFUSE
BOUNDARY...WILL ONLY CARRY MENTION OF POSSIBLE TSRA IN A PROB30 GROUP.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN VIS TREND OVERNIGHT AND CHANCES FOR MVFR
DURG THE EARLY MORNING HOURS.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
* LOW CONFIDENCE IN PCPN FORECAST TOMORROW EVENING.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
* FRIDAY THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH PERIODIC
CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE FRIDAY
INTO THE WEEKEND.
KJB
&&
.MARINE...
240 PM CDT
GENERALLY SOUTHERLY WINDS SHOULD CONTINUE THROUGH THURSDAY
EVENING...THOUGH PERIODIC PASSAGE OF THUNDERSTORM CLUSTERS COULD
RESULT IN VARIABLE AND AT TIMES STRONGER WINDS. FRONT WILL DROP DOWN
THE LAKE THURSDAY NIGHT INTO FRIDAY MORNING RESULTING IN A WIND
SHIFT TO NORTHERLY TO NORTHEASTERLY. WINDS LIKELY TO REMAIN
NORTHEAST TO EAST INTO EARLY NEXT WEEK AS FRONT REMAINS STALLED OUT
TO THE SOUTHWEST OF THE LAKE AND HIGH PRESSURE REMAINS SITUATED OVER
EASTERN CANADA.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
405 AM CDT THU MAY 3 2012
.SHORT TERM /TODAY/...
FORECAST CONCERN INVOLVES THE ONGOING CONVECTION ASSOCIATED WITH A
DYING MCS MOVING ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA
THIS MORNING. LATEST HRRR (05Z RUN) HAS CONVECTION DISSIPATING AND
MOVING EAST THROUGH 15Z AND THE 00Z 4KM WRF HAS CONVECTION
DISSIPATING BY AROUND 18Z IN EASTERN PORTIONS OF THE FORECAST AREA.
Q2 CURRENTLY DEPICTING RAINFALL RATES AROUND 2 IN/HR OR LESS WITHIN
THE STRONGER CORES...BUT LINE IS MOVING FAIRLY PROGRESSIVE AT
30-35KTS. SO NOT ANTICIPATING MUCH FLOODING ISSUES...ESPECIALLY
FURTHER EAST WITHIN THE FLASH FLOOD WATCH AREA IN NORTHEAST IOWA.
CONVECTION SHOULD BE MUCH WEAKER BY THE TIME IT REACHES IT AND
THUS...WENT AHEAD AND CANCELLED FLASH FLOOD WATCH.
OTHER CONCERN IS WITH POTENTIAL FOR AFTERNOON CONVECTION ALONG AND
SOUTH OF THE BOUNDARY IN NORTHERN IOWA. RUC/NAM/GFS ALL KEEP THE
SURFACE FRONT LAID UP ALONG THE MN/IA BORDER KEEPING THE FORECAST
AREA WITHIN THE WARM SECTOR. BEST INSTABILITY WILL BE LOCATED SOUTH
OF HIGHWAY 30 WHERE LOW LEVEL CAPE INCREASES TO AROUND 2000-3000
J/KG BUT LOW LEVEL SHEAR VALUES NOT IMPRESSIVE. CLOUDS LEFTOVER FROM
DYING MCS SHOULD LIMIT SOME OF THE DAYTIME HEATING...BUT THINKING
THE WAA WILL BE STRONG ENOUGH TO BUMPED TEMPS BACK INTO THE LOWER
80S BY THIS AFTERNOON. TIMING OF AFTERNOON CONVECTION LOOKS TO BE
AFTER 21Z WITH MID-LEVEL SHORTWAVE MOVING INTO WESTERN IOWA BY 00Z
FRIDAY. SURFACE DEW POINTS REMAIN WELL INTO THE 60S...SO PLENTY OF
MOISTURE AVAILABLE.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
CURRENT LONG WAVE PATTERN...WRN CONUS TROUGH/ERN RIDGE...WILL REMAIN
INTACT THROUGH MUCH OF THE PERIOD BUT WITH SLOW PROGRESS. THIS
SHOULD HAVE TROUGH ONLY REACH CENTRAL CONUS BY EARLY NEXT WEEK.
EXPECT CONVERGENCE FROM CURRENT NE TO MN FRONTAL BOUNDARY AND/OR
OUTFLOW FROM WEAKENING WRN IA MCS TO EVENTUALLY POSITION ITSELF INTO
CENTRAL/SRN IA BY EARLY THIS EVENING AND TRIGGER ANOTHER ROUND OF
CONVECTION...TIMED MUCH LIKE PAST FEW EVENTS MAINLY AT NIGHT. MCS
SHOULD THEN PUSH TO THE SOUTH AND EAST DIMINISHING POPS OVERNIGHT.
CONFIDENCE IN THIS SCENARIO IS SOMEWHAT LOW HOWEVER AS CURRENT MCS
CONTINUES TO BACK BUILD ACROSS SRN NE. FORECASTING EVENTUAL
POSITION OF SYNOPTIC AND/OR MESOSCALE BOUNDARIES WILL BE DIFFICULT.
BY FRI MODEL CONSENSUS SUGGESTS A RELATIVE LULL WITH IA IN FAIRLY
WEAK SELY SURFACE FLOW. STILL UNSTABLE BUT LITTLE FOCUS. ATTENTION
TURNS TO THE WEST AGAIN EYING RESPONSE TO GRADUALLY APPROACHING
WRN TROUGH. THIS WILL LEAD TO INCREASING WARM ADVECTION AND
BAROCLINICITY THROUGH SIOUXLAND MO VALLEY REGION. 305K FLOW IS
FAIRLY WEAK SO DO NOT EXPECT SIGNIFICANT MCS BUT INCREASING POPS.
CONVECTION MAY BE MORE SIGNIFICANT BY SAT NIGHT AND SUNDAY HOWEVER
AS FLOW AND ASSOCIATED THETA-E ADVECTION INCREASE. KINEMATIC
FORCING WILL INCREASE AS WELL AS LOBE OF UVM PUSHES ACROSS NRN
PLAINS INTO EARLY SUN WHICH IS ALSO FOCUSED BY PASSAGE OF INVERTED
SURFACE TROUGH. THIS ALL LEADS TO POPS BACK UP INTO LIKELIES DURING
THIS PERIOD.
BY EARLY NEXT WEEK PATTERN WILL SHIFT SUFFICIENTLY TO LOWER OUR
PRECIP CHANCES AND COOL TEMPS SOMEWHAT AS IA ENDS UP IN NWLY SURFACE
FLOW. THIS RESULTS IN EXTENDED FORECAST EITHER DRY OR WITH ONLY
SLIGHT CHANCES AND MAXES ONLY IN THE 60S OR POSSIBLY LOWER 70S.
&&
.AVIATION...03/06Z
THUNDERSTORM ACTIVITY CONTINUES TO BE MOSTLY NON-EXISTENT ACROSS THE
CWA...WITH A FEW CELLS PUSHING THROUGH EXTREME NORTHERN CWA. FORCING
FOR THUNDERSTORMS REMAINS STRONGER TO THE WEST OF THE CWA...AND
STILL MAY GET SOME MOVING THROUGH THE AREA LATE TONIGHT TOWARD
SUNRISE OR A LITTLE BEFORE. THEREFORE HAVE GONE MORE PESSIMISTIC
WITH THE TAFS AND ONLY MENTIONED VCSH FOR KDSM AND KOTM WHERE THE
BETTER CHANCES WILL BE VERSUS THE NORTHERN CWA AT THIS TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KLP
LONG TERM...BSS
AVIATION...MJB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1205 AM CDT THU MAY 3 2012
.UPDATE...
PREVIOUS THOUGHTS OF CONVECTION DEVELOPING ACROSS NORTHERN IOWA IN
THE LATE AFTERNOON/EARLY EVENING HAVE NOT OCCURRED...WITH DECENT CAP
STILL IN PLACE ALOFT VIA DVN 00Z SOUNDING DUE TO STRATUS/LOW CLOUD
COVER LINGERING MUCH OF THE DAY. THEREFORE HAVE TAPERED POPS DOWN
FOR THE EARLY EVENING HOURS AT THIS TIME. A FEW CELLS ARE TRYING TO
GO UP ON SFC BOUNDARY SITUATED ACROSS ERN NE/SE SD INTO SRN MN.
THESE CELLS HAVING TOUGHER TIME SUSTAINING THEMSELVES AS WELL.
THEREFORE FOCUS ON THUNDERSTORM DEVELOPMENT TURNS TO LATER TONIGHT
WITH MID LEVEL WAVE APPROACHES FROM THE WEST AND LLJ INCREASES AND
LOW LEVEL MOISTURE TRANSPORT BECOMES ORIENTED RIGHT INTO CENTRAL
IOWA. HRRR MODEL SUGGESTING STORMS PUSHING INTO CENTRAL IOWA AROUND
MIDNIGHT OR LATER AT THIS TIME...SO HAVE TRENDED GREATEST POPS
ACROSS THE CWA FOR THE LATE NIGHT HOURS.
.SHORT TERM /TONIGHT/...
SEVERAL CONCERNS OVERNIGHT AS ACTIVE WSW FLOW ALOFT CONTINUES.
OUTFLOW FROM THE MORNING CONVECTION HAD CLEARED WELL SOUTH OF THE
BORDER EARLIER TODAY AND THERE HAS BEEN GRADUAL RECOVER THROUGH THE
AFTERNOON AS SOUTHERLY WINDS HAVE INCREASED ALONG WITH MOISTURE.
CAPES HAVE STEADILY INCREASED WITH 100MB MIXED LAYER OF 2000-3000
J/KG ACROSS WESTERN AND NORTHERN IOWA. HOWEVER...18Z SOUNDING AT
KOAX HAS INDICATED SOME CAPPING ALONG WITH A GENERALLY DIVERGENT
SURFACE FLOW IN NORTHERN IOWA. THESE PARTICULAR FEATURES ARE LIKELY
INHIBITING CONVECTION AT THIS POINT BUT THIS SHOULD CHANGE BY THIS
EVENING WITH THE APPROACH OF A SHORTWAVE IN THE PLAINS. MODELS HAVE
BEEN INDICATING CONVECTION IN NORTH CENTRAL AND NORTHEAST IOWA THIS
EVENING WHERE LOW LEVEL JET/FLOW WILL BE DIRECTED. THIS AREA HAS
VERY HIGH PWATS AND WITH THIS PERSISTENT LOW LEVEL FLOW DIRECTED IN
THAT LOCATION AND FLASH FLOOD GUIDANCE VALUES OF ONE TO ONE AND A
HALF INCHES...HAVE OPTED FOR A FLASH FLOOD WATCH IN FAR NORTHEAST.
ELSEWHERE...CONVECTION EXPECTED IN THE NORTH THIS EVENING WHERE CAP
IS WEAKEST WITH ADDITIONAL CONVECTION IN NEBRASKA HEADING TOWARD
CENTRAL AND SOUTHERN IOWA LATE TONIGHT INTO EARLY THURSDAY MORNING.
THIS CONVECTION WILL HAVE THE THREAT FOR SEVERE STRAIGHT LINE WINDS
ALONG WITH LARGE HAIL AND A ISOLATED TORNADOES AS IT PROGRESSES
RAPIDLY EASTWARD OVERNIGHT.
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
COMPLICATED LONG TERM FORECAST...WITH LOW CONFIDENCE. ANTICIPATE
OVERNIGHT MCS TO BE LINGERING ACROSS THE NORTH AND EAST FOR
BEGINNING OF TOMORROW BEFORE PUSHING OUT OF CWA. CONDITIONS WILL
IMPROVE THROUGH THE DAY...BUT WITH LINGERING FRONTAL BOUNDARY ACROSS
SOUTHERN IOWA BY THURSDAY AFTERNOON...EXPECT TO SEE AFTERNOON
DEVELOPMENT. BUT AGAIN ANTICIPATE BEST CHANCES FOR PRECIPITATION TO
BE ANOTHER ROUND OF OVERNIGHT MCS CONVECTION...FOCUSED ACROSS
SOUTHERN IOWA. PWAT VALUES ARE HIGH...WITH PLENTY OF MOISTURE
AVAILABLE COULD SEE POTENTIAL FOR LOCALIZED AREAS OF HEAVY RAIN
AGAIN OVERNIGHT THURSDAY NIGHT...AGAIN HIGHEST LIKELIHOOD APPEARS TO
BE ACROSS SOUTHERN IOWA. OVERNIGHT PRECIPITATION COULD LINGER INTO
EARLY FRIDAY BEFORE AGAIN QUICKLY PUSHING OUT OF THE CWA. HAVE LEFT
SLIGHT CHANCE POPS FOR FRIDAY AFTERNOON WITH POTENTIAL FOR AFTERNOON
DEVELOPMENT WITH ANOTHER APPROACHING FRONTAL SYSTEM...BUT AGAIN
APPEARS MAIN PRECIP CHANCES WILL BE OVERNIGHT.
TEMPERATURES BECOME A BIT TRICKY FOR FRIDAY AND SATURDAY. WAA AHEAD
OF APPROACHING FRONTAL SYSTEM IS STRONG FOR FRIDAY WITH GOOD MIXING
POSSIBLE FRIDAY. IF MIXING IS FULLY REALIZED...OR SKIES CLEAR FOR
LONG ENOUGH COULD EASILY SEE TEMPERATURES POP UP INTO THE UPPER 80S
FOR MUCH OF THE CENTRAL AND SOUTHERN PORTIONS OF THE CWA. HAVE
INCREASED TEMPERATURES FOR FRIDAY AND SATURDAY...BUT MAY STILL HAVE
BEEN TOO COOL...ESPECIALLY FOR FRIDAY. TIMING OF FRONTAL BOUNDARY
WILL HAVE IMPACT ON TEMPS FOR SATURDAY...WITH LITTLE MODEL AGREEMENT
ON PLACING OF FRONT HAVE TRENDED UPWARDS WITH TEMPS.
ACTIVE PATTERN CONTINUES FOR REMAINDER OF EXTENDED WITH AREA OF LOW
PRESSURE EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS/SOUTHERN CANADA
FOR THE END OF EXTENDED. ASSOCIATED FRONTAL BOUNDARYS WILL BRING
CHANCES FOR PRECIPITATION THROUGH THE WEEKEND...WITH LINGERING
PRECIPITATION INTO EARLY NEXT WEEK.
&&
.AVIATION...03/06Z
THUNDERSTORM ACTIVITY CONTINUES TO BE MOSTLY NON-EXISTENT ACROSS THE
CWA...WITH A FEW CELLS PUSHING THROUGH EXTREME NORTHERN CWA. FORCING
FOR THUNDERSTORMS REMAINS STRONGER TO THE WEST OF THE CWA...AND
STILL MAY GET SOME MOVING THROUGH THE AREA LATE TONIGHT TOWARD
SUNRISE OR A LITTLE BEFORE. THEREFORE HAVE GONE MORE PESSIMISTIC
WITH THE TAFS AND ONLY MENTIONED VCSH FOR KDSM AND KOTM WHERE THE
BETTER CHANCES WILL BE VERSUS THE NORTHERN CWA AT THIS TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH THURSDAY
MORNING FOR BLACK HAWK-BREMER-BUTLER-CERRO GORDO-FRANKLIN-GRUNDY-
HARDIN.
&&
$$
SHORT TERM...COGIL
LONG TERM...AWB
AVIATION...MJB
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
314 AM CDT THU MAY 3 2012
...UPDATED LONG TERM DISCUSSION...
.SYNOPSIS...
ISSUED AT 234 AM CDT THU MAY 3 2012
THE 03.00Z 250 HPA SYNOPTIC MAP SHOWED A SEGMENTED POLAR JET WITH A
90 KT JET PUSHING ASHORE ACROSS THE PACIFIC NORTHWEST. ANOTHER 110
KT JET STREAK WAS LOCATED ACROSS THE NORTHERN PLAINS WITH THE RIGHT
ENTRANCE REGION FAIRLY CLOSE TO KANSAS (AND COULD HAVE BEEN PARTIALLY
RESPONSIBLE FOR CONVECTION EARLIER). ANOTHER 100 KT JET WAS LOCATED
ACROSS NEW ENGLAND. AT 500 HPA, VERY COLD TEMPERATURES OF -25 TO -31
DEG C WERE OBSERVED ACROSS BRITISH COLUMBIA AND EXTENDING EASTWARDS
ACROSS THE CANADIAN PRAIRIES AND AS FAR SOUTH AS NORTHEASTERN MONTANA.
SEVERAL MID LEVEL SHORTWAVE TROUGH WERE ANALYZED ACROSS THE CONUS MID
ATMOSPHERE. CLOSER TO KANSAS AND IN THE LOWER LEVELS, A WARM AND DRY
PLUME (EML) EXTENDED ACROSS THE KANSAS AND SOUTHWARD INTO THE SOONER/LONE
STAR STATES. AT THE SURFACE, A LOW PRESSURE CENTER WAS LOCATED ACROSS
FAR SOUTHWESTERN KANSAS. A DRYLINE ASSOCIATED WITH THIS SURFACE LOW
EXTENDED ACROSS SOUTHWEST KANSAS AND SOUTHWARD INTO TEXAS. DEWPOINTS
IN THE 60S DEG F WERE EAST OF THIS BOUNDARY. A WEAK COLD FRONT WAS PUSHING
ACROSS EAST CENTRAL COLORADO AND INTO NORTHWEST KANSAS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 234 AM CDT THU MAY 3 2012
THIS MORNING:
A COLD FRONT IS MOVING ACROSS NORTHWESTERN KANSAS EARLY THIS MORNING.
THIS FRONT WILL MAKE ITS WAY AT LEAST THROUGH 2/3RD`S OF THE REGION
AND STALL ROUGHLY FROM MEADE TO LARNED. HRRR INDICATES SOME POST FRONTAL
STRATUS VIA UPSLOPE FLOW ACROSS INTERSTATE 70 SO HAVE INCREASED CLOUD
COVER AS A RESULT DURING THE MORNING FOR THIS AREA. TODAY WILL START
OUT QUITE MILD AS DEWPOINTS EAST OF THE DRYLINE ARE WELL INTO THE 60S
DEG F. THIS WAS UNDER FORECAST BY SEVERAL OF THE MODELS. NO PRECIPITATION
IS EXPECTED ALONG THE FRONTAL BOUNDARY DUE TO SUBSIDENCE ALOFT/NO UPPER
LEVEL SUPPORT.
TODAY:
THE HOTTEST TEMPERATURES ARE LIKELY SOUTH OF THE FRONTAL WHICH WILL
STALL ACROSS THE AFOREMENTIONED MEADE TO LARNED LINE. LOW TO MID 90S
DEG F ARE POSSIBLE ACROSS SOUTH CENTRAL KANSAS. FURTHER NORTHWEST, THERE
WILL BE ENOUGH INSOLATION AND MIXING TO ALLOW TEMPERATURES TO PEAK INTO
THE MID TO UPPER 80S DEG F.
THIS EVENING:
I HAVE COMPROMISED BETWEEN SEVERAL MODELS AND HAVE SLIGHT POPS ROUGHLY
NORTHWEST FROM A HAYS TO ELKHART LINE. 00Z NAM/WRF/NMM ARE IN FAIRLY
GOOD AGREEMENT WITH THE POSSIBILITY OF UPSLOPE AND FRONTAL RELATED CONVECTION
ACROSS SOUTHEASTERN COLORADO INTO FAR SW/W KANSAS. THE GFS IS A BIT
DIFFERENT WITH BETTER CONVECTIVE CHANCES ALONG INTERSTATE 70. AS A RESULT,
HAVE BLENDED POPS BETWEEN THE MODELS. THERE MAY BE A WEAK MID LEVEL
SHORTWAVE TROUGH AS SEEN ACROSS THE ROCKIES EARLY THIS MORNING THAT
COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT FOR THUNDERSTORMS. OTHERWISE,
UPPER LEVEL SUPPORT TODAY IS QUITE WEAK. FORECAST SOUNDINGS ACROSS
FAR WESTERN KANSAS SHOW ABOUT 1500 J/KG OF CAPE AND A BIT OF VEERING
IN THE WIND PROFILE, ALTHOUGH SPEED SHEAR IS RATHER WEAK. THE THERMODYNAMIC
PROFILE IS WELL MIXED TO ABOUT 600 HPA SO IF CONVECTION DOES FORM, THEN
DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT AND PERHAPS MARGINAL SEVERE
HAIL SINCE 0 TO 6 KM SHEAR IS ONLY FORECAST TO BE ABOUT 25-30 KT. WITH
THIS EXCEPTION OF A VERY MARGINAL CHANCE OF AN ISOLATED THUNDERSTORM,
THE FORECAST WILL REMAIN DRY. OVERNIGHT LOWS HEADING INTO FRIDAY MORNING
WILL BE MILD AGAIN WITH 50S DEG F TOWARDS GARDEN CITY AND 60S DEG F
TOWARDS MEDICINE LODGE DUE TO MODERATE DEWPOINTS AND WEAK LEE TROUGH/RESULTANT
SOUTHERLY WINDS THROUGH THE OVERNIGHT PERIOD.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 309 AM CDT THU MAY 3 2012
BOTH THE NAM AND GFS ARE IN GOOD AGREEMENT WITH A SUBTLE UPPER
LEVEL DISTURBANCE CROSSING SOUTHWEST KANSAS EARLY DAY ON FRIDAY.
AS THIS SYSTEM CROSSES WESTERN KANSAS A SURFACE BOUNDARY WILL
EXTEND FROM WEST TO EAST NORTH OF INTERSTATE 70 AND A DRYLINE IS
EXPECTED TO STRETCH FROM THIS SURFACE BOUNDARY SOUTH INTO WESTERN
OKLAHOMA. AT THIS TIME BASED ON THE TIMING OF THIS SUBTLE FEATURE
AND WARM MID LEVEL TEMPERATURES FORECAST FRIDAY AFTERNOON WILL
CONTINUE TO FAVOR A DRY FORECAST FRIDAY AND FRIDAY NIGHT ACROSS
WESTERN KANSAS. MODEL SOUNDINGS INDICATING A DECENT MIXING DEPTH
AND BASED ON 850MB TEMPERATURES AT 00Z SATURDAY WILL CONTINUE TO
FAVOR HIGHS AT LEAST IN THE LOW TO MID 90S.
A STRONGER UPPER LEVEL TROUGH WILL BEGIN TO CROSS WESTERN UNITED
STATES LATE FRIDAY. AN UPPER LEVEL JET IS FORECAST TO BEGIN TO
MOVE FROM THE BASE OF THIS TROUGH AND EJECT OUT INTO THE WEST
CENTRAL HIGH PLAINS BY EARLY THIS WEEKEND. AS THIS NEXT SYSTEM
APPROACHES EARLY THIS WEEKEND AN AREA OF LOW PRESSURE IS EXPECTED
TO DEEPEN ACROSS EASTERN COLORADO/WESTERN KANSAS. BY 00Z SUNDAY
700MB TEMPERATURES ACROSS WESTERN KANSAS ARE FORECAST TO RANGE
FROM +10 TO +12C AND THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL
JET IS EXPECTED TO BE LOCATED NEAR NORTHEAST COLORADO. BASED ON
THE LOCATION OF THE UPPER JET, 925-850MB THTA-E RIDGE
AXIS/MOISTURE ADVECTION AND NORTHERN EDGE OF THE WARM 700MB
TEMPERATURES WILL FAVOR LATE DAY AND EARLY SATURDAY NIGHT
CONVECTION STAYING NORTH OF THE AREA. TEMPERATURES SATURDAY WILL
ONCE AGAIN BE WARM AND BASED ON 850MB TEMPERATURES AND THE
FORECAST MIXED LAYER THE HIGHS SATURDAY AFTERNOON SHOULD CLIMB
ONCE AGAIN BACK INTO THE LOW TO MID 90S.
BY EARLY SUNDAY THE UPPER JET WILL MOVE OUT INTO THE NORTHERN
PLAINS AND A COLD FRONT IS FORECAST TO SURGE SOUTH INTO WESTERN
KANSAS. A TIGHT SURFACE PRESSURE GRADIENT AND STRONG BOUNDARY
LAYER TO 850MB WINDS ARE FORECAST BEHIND THIS FRONT WITH A NET 24
HOUR 850MB TEMPERATURE CHANCE FROM 00Z SUNDAY TO 00Z MONDAY
AVERAGING FROM 8-12C DEGREES COOLER. AS A RESULT WILL UNDERCUT MAX
TEMPERATURES ON SUNDAY AND TREND TOWARDS THE COOLER 00Z MONDAY
ECMWF/GFS 850MB MIX DOWN TEMPERATURES. MOISTURE SOMEWHAT LIMITED
WITH THIS FRONT AND UPPER LEVEL DYNAMICS APPEAR TO REMAIN NORTH OF
THE AREA SO PRECIPITATION CHANCES STILL APPEAR SMALL BUT DID
INSERT SOME SMALL POPS EARLY SUNDAY NEAR AND NORTH OF INTERSTATE
70.
ON MONDAY ISENTROPIC LIFT/850-700MB WARM AIR ADVECTION BEGINS TO
IMPROVE ACROSS EASTERN COLORADO AND WESTERN KANSAS. ON MONDAY
NIGHT ANOTHER UPPER LEVEL TROUGH WILL BEGIN TO APPROACH THE WEST
CENTRAL PLAINS WHICH SHOULD PROVIDE THE NEXT DECENT OPPORTUNITY
FOR MEASURABLE PRECIPITATION TO PORTIONS OF WESTERN KANSAS TUESDAY
AND WEDNESDAY AS MOISTURE AND ISENTROPIC LIFT/WARM AIR ADVECTION
CONTINUES ACROSS WESTERN KANSAS. IN ADDITION GIVEN THE CLOUD COVER
EXPECTED TUESDAY AND WEDNESDAY WILL CONTINUE TO FAVOR THE PREVIOUS
FORECAST WITH HIGHS MAINLY IN THE UPPER 60S TO LOWER
70S...ESPECIALLY ON TUESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1200 AM CDT THU MAY 3 2012
MVFR CIGS ARE INDICATED BY MOS GUIDANCE AS WELL AS THE 01Z HRRR FOR
KHYS IN ASSOCIATION WITH WITH POST FRONTAL UPSLOPE STRATUS. THE RELATED
FRONT WILL MOVE THROUGH KGCK AND KDDC EARLY IN THE MORNING AS WELL,
HOWEVER, ENOUGH MIXING LOOKS TO KEEP CIGS AT VFR. THIS FRONT WILL STALL
OUT THROUGH THE DAY AND RETURN NORTH AS A WARM FRONT BY EVENING. WINDS
SHOULD GENERALLY BE LIGHT (8 TO 13 KT) WITH A GRADUAL VEERING IN DIRECTION
WITH THE RETURN OF THE WARM FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 88 56 95 61 / 10 10 0 0
GCK 86 55 94 58 / 10 20 0 0
EHA 89 56 93 59 / 20 20 0 0
LBL 89 58 96 60 / 10 10 0 0
HYS 85 60 93 62 / 10 20 0 10
P28 93 66 92 66 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SUGDEN
SHORT TERM...SUGDEN
LONG TERM...BURGERT
AVIATION...SUGDEN
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
234 AM CDT THU MAY 3 2012
...UPDATE TO SYNOPSIS AND SHORT TERM DISCUSSIONS...
.SYNOPSIS...
ISSUED AT 234 AM CDT THU MAY 3 2012
THE 03.00Z 250 HPA SYNOPTIC MAP SHOWED A SEGMENTED POLAR JET WITH A
90 KT JET PUSHING ASHORE ACROSS THE PACIFIC NORTHWEST. ANOTHER 110
KT JET STREAK WAS LOCATED ACROSS THE NORTHERN PLAINS WITH THE RIGHT
ENTRANCE REGION FAIRLY CLOSE TO KANSAS (AND COULD HAVE BEEN PARTIALLY
RESPONSIBLE FOR CONVECTION EARLIER). ANOTHER 100 KT JET WAS LOCATED
ACROSS NEW ENGLAND. AT 500 HPA, VERY COLD TEMPERATURES OF -25 TO -31
DEG C WERE OBSERVED ACROSS BRITISH COLUMBIA AND EXTENDING EASTWARDS
ACROSS THE CANADIAN PRAIRIES AND AS FAR SOUTH AS NORTHEASTERN MONTANA.
SEVERAL MID LEVEL SHORTWAVE TROUGH WERE ANALYZED ACROSS THE CONUS MID
ATMOSPHERE. CLOSER TO KANSAS AND IN THE LOWER LEVELS, A WARM AND DRY
PLUME (EML) EXTENDED ACROSS THE KANSAS AND SOUTHWARD INTO THE SOONER/LONE
STAR STATES. AT THE SURFACE, A LOW PRESSURE CENTER WAS LOCATED ACROSS
FAR SOUTHWESTERN KANSAS. A DRYLINE ASSOCIATED WITH THIS SURFACE LOW
EXTENDED ACROSS SOUTHWEST KANSAS AND SOUTHWARD INTO TEXAS. DEWPOINTS
IN THE 60S DEG F WERE EAST OF THIS BOUNDARY. A WEAK COLD FRONT WAS PUSHING
ACROSS EAST CENTRAL COLORADO AND INTO NORTHWEST KANSAS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 234 AM CDT THU MAY 3 2012
THIS MORNING:
A COLD FRONT IS MOVING ACROSS NORTHWESTERN KANSAS EARLY THIS MORNING.
THIS FRONT WILL MAKE ITS WAY AT LEAST THROUGH 2/3RD`S OF THE REGION
AND STALL ROUGHLY FROM MEADE TO LARNED. HRRR INDICATES SOME POST FRONTAL
STRATUS VIA UPSLOPE FLOW ACROSS INTERSTATE 70 SO HAVE INCREASED CLOUD
COVER AS A RESULT DURING THE MORNING FOR THIS AREA. TODAY WILL START
OUT QUITE MILD AS DEWPOINTS EAST OF THE DRYLINE ARE WELL INTO THE 60S
DEG F. THIS WAS UNDER FORECAST BY SEVERAL OF THE MODELS. NO PRECIPITATION
IS EXPECTED ALONG THE FRONTAL BOUNDARY DUE TO SUBSIDENCE ALOFT/NO UPPER
LEVEL SUPPORT.
TODAY:
THE HOTTEST TEMPERATURES ARE LIKELY SOUTH OF THE FRONTAL WHICH WILL
STALL ACROSS THE AFOREMENTIONED MEADE TO LARNED LINE. LOW TO MID 90S
DEG F ARE POSSIBLE ACROSS SOUTH CENTRAL KANSAS. FURTHER NORTHWEST, THERE
WILL BE ENOUGH INSOLATION AND MIXING TO ALLOW TEMPERATURES TO PEAK INTO
THE MID TO UPPER 80S DEG F.
THIS EVENING:
I HAVE COMPROMISED BETWEEN SEVERAL MODELS AND HAVE SLIGHT POPS ROUGHLY
NORTHWEST FROM A HAYS TO ELKHART LINE. 00Z NAM/WRF/NMM ARE IN FAIRLY
GOOD AGREEMENT WITH THE POSSIBILITY OF UPSLOPE AND FRONTAL RELATED CONVECTION
ACROSS SOUTHEASTERN COLORADO INTO FAR SW/W KANSAS. THE GFS IS A BIT
DIFFERENT WITH BETTER CONVECTIVE CHANCES ALONG INTERSTATE 70. AS A RESULT,
HAVE BLENDED POPS BETWEEN THE MODELS. THERE MAY BE A WEAK MID LEVEL
SHORTWAVE TROUGH AS SEEN ACROSS THE ROCKIES EARLY THIS MORNING THAT
COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT FOR THUNDERSTORMS. OTHERWISE,
UPPER LEVEL SUPPORT TODAY IS QUITE WEAK. FORECAST SOUNDINGS ACROSS
FAR WESTERN KANSAS SHOW ABOUT 1500 J/KG OF CAPE AND A BIT OF VEERING
IN THE WIND PROFILE, ALTHOUGH SPEED SHEAR IS RATHER WEAK. THE THERMODYNAMIC
PROFILE IS WELL MIXED TO ABOUT 600 HPA SO IF CONVECTION DOES FORM, THEN
DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT AND PERHAPS MARGINAL SEVERE
HAIL SINCE 0 TO 6 KM SHEAR IS ONLY FORECAST TO BE ABOUT 25-30 KT. WITH
THIS EXCEPTION OF A VERY MARGINAL CHANCE OF AN ISOLATED THUNDERSTORM,
THE FORECAST WILL REMAIN DRY. OVERNIGHT LOWS HEADING INTO FRIDAY MORNING
WILL BE MILD AGAIN WITH 50S DEG F TOWARDS GARDEN CITY AND 60S DEG F
TOWARDS MEDICINE LODGE DUE TO MODERATE DEWPOINTS AND WEAK LEE TROUGH/RESULTANT
SOUTHERLY WINDS THROUGH THE OVERNIGHT PERIOD.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 320 PM CDT WED MAY 2 2012
MEDIUM RANGE MODELS INDICATE AN UPPER LEVEL TROUGH OF LOW PRESSURE
PUSHING ASHORE INTO THE PACIFIC NORTHWEST FRIDAY THEN CONTINUING TO
TRACK EASTWARD ACROSS THE NORTHERN ROCKIES SATURDAY, AND INTO THE
NORTHERN PLAINS ALONG THE CANADIAN BORDER BY THE END OF THE WEEKEND.
THIS SYSTEM WILL BRING THE POSSIBILITY FOR SHOWERS AND THUNDERSTORMS
FROM THE NORTHERN PLAINS SOUTHWARD INTO PORTIONS OF NEBRASKA AND
KANSAS THROUGHOUT THE WEEKEND. AN ATTENDANT COLD FRONT TO THE UPPER
LEVEL SYSTEM IS PROGGED TO PUSH SOUTHEAST INTO WESTERN KANSAS
SOMETIME EARLY SUNDAY SETTING UP THE CHANCE FOR PRECIP ACROSS
PORTIONS OF WESTERN KANSAS BY LATE SUNDAY INTO EARLY MONDAY.
ALTHOUGH MODELS BEGIN TO DIVERGE EARLY NEXT WEEK, ALL SHOW UPPER
LEVEL TROUGHING DEEPENING ACROSS THE INTERMOUNTAIN WEST SETTING UP A
SOUTHWESTERLY FLOW ALOFT ACROSS THE WESTERN HIGH PLAINS. MEANWHILE,
A SERIES OF H5 VORT MAXES ARE LIKELY TO EJECT NORTHEAST OUT OF THE
TROUGH, AND ALONG WITH PLENTY OF LOW LEVEL MOISTURE AVAILABLE,
INCREASE CHANCES FOR PRECIP VIRTUALLY EACH DAY THROUGH THE END OF
THE PERIOD.
TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL FRIDAY AS UPPER LEVEL
TROUGHING BEGINS TO PUSH EAST ACROSS THE INTERMOUNTAIN WEST. AS THE
UPPER LEVEL SYSTEM APPROACHES FROM THE WEST, A SURFACE TROUGH LEE OF
THE ROCKIES WILL HELP INFLUENCE A LOW LEVEL SOUTH TO SOUTHWESTERLY
FLOW ACROSS WESTERN KANSAS. THIS WILL ENHANCE WARM AIR ADVECTION
INTO THE AREA WITH H85 TEMPERATURES RANGING FROM THE MID 20S(C)
ACROSS CENTRAL KANSAS TO THE UPPER 20S(C) NEAR THE COLORADO BORDER.
SO, WITH THE NAM, GFS, AND GEM SHOWING DRY LAPSE RATES IN THE LOWER
LEVELS, LOOK FOR HIGHS UP INTO THE LOWER TO MID 90S(F) FRIDAY
AFTERNOON. SIMILAR HIGHS ARE LIKELY SATURDAY WITH LEE SIDE TROUGHING
PERSISTING NEAR THE COLORADO BORDER AND H85 TEMPERATURES CHANGING
VERY LITTLE. GENERALLY COOLER TEMPERATURES ARE THEN EXPECTED SUNDAY
AS A COLD FRONT IS PROJECTED TO PUSH INTO WESTERN KANSAS SOMETIME
DURING THE DAY ALLOWING COOLER AIR TO FILTER SOUTH INTO WESTERN
KANSAS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1200 AM CDT THU MAY 3 2012
MVFR CIGS ARE INDICATED BY MOS GUIDANCE AS WELL AS THE 01Z HRRR FOR
KHYS IN ASSOCIATION WITH WITH POST FRONTAL UPSLOPE STRATUS. THE RELATED
FRONT WILL MOVE THROUGH KGCK AND KDDC EARLY IN THE MORNING AS WELL,
HOWEVER, ENOUGH MIXING LOOKS TO KEEP CIGS AT VFR. THIS FRONT WILL STALL
OUT THROUGH THE DAY AND RETURN NORTH AS A WARM FRONT BY EVENING. WINDS
SHOULD GENERALLY BE LIGHT (8 TO 13 KT) WITH A GRADUAL VEERING IN DIRECTION
WITH THE RETURN OF THE WARM FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 88 56 95 61 / 10 10 0 0
GCK 86 55 94 58 / 10 20 0 0
EHA 89 56 93 59 / 20 20 0 0
LBL 89 58 96 60 / 10 10 0 0
HYS 85 60 93 62 / 10 20 0 0
P28 93 66 92 66 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SUGDEN
SHORT TERM...SUGDEN
LONG TERM...JJOHNSON
AVIATION...SUGDEN
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1200 AM CDT THU MAY 3 2012
...UPDATE TO AVIATION FOR 06Z TAFS...
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 250 PM CDT WED MAY 2 2012
THE 12Z UPPER AIR ANALYSIS WAS SHOWING A SHORTWAVE TROUGH OVER IDAHO
AND NORTHERN NEVADA. AN ASSOCIATED 110 KNOT JET STREAK AT THE 250
MILLIBAR LEVEL WAS CENTERED OVER RAPID CITY, SOUTH DAKOTA. FARTHER
SOUTH THE MID AND UPPER LEVEL FLOW WAS FAIRLY WEAK OVER WESTERN
KANSAS. AT THE SURFACE...A WEAK COOL FRONT HAD PUSHED SOUTH ACROSS
WESTERN KANSAS EARLY THIS MORNING. THE FRONT WAS SLOW TO ERODE
THIS AFTERNOON BUT LIGHT AND VARIABLE SURFACE WINDS ARE BEGINNING
TO SWITCH AROUND TO A SOUTHERLY DIRECTION OVER PARTS OF SOUTHWEST
KANSAS.
AS THE NORTHERN PLAINS SHORTWAVE TROUGH MOVES EAST TONIGHT...WEAK
LOW PRESSURE OVER EASTERN COLORADO WILL TRACK OUT ACROSS KANSAS
WITH THE WEAK COLD FRONT PUSHING SOUTH THROUGH WESTERN KANSAS
AGAIN LATE TONIGHT. A FAIR AMOUNT OF SURFACE BASED INSTABILITY IS
IN PLACE OVER WESTERN KANSAS BUT IS BEING CAPPED OFF BY WARM MID
LEVEL TEMPERATURES. THINK THAT ANY THUNDERSTORMS LATE THIS
AFTERNOON WOULD BE CONFINED TO THE AREA ALONG AND NORTH OF I-70.
WILL CARRY A SLIGHT CHANCE FOR EVENING STORMS IN THAT AREA BUT
KEEP IT DRY FARTHER SOUTH.
ON THURSDAY THE MODELS SHOW THE FRONTAL BOUNDARY WASHING OUT
ACROSS SOUTHWEST KANSAS. TEMPERATURES ALONG AND NORTH OF THE
OKLAHOMA BORDER SHOULD BE ABLE TO CLIMB TO AROUND 90 OR EVEN INTO
THE LOWER 90S BUT FARTHER NORTH EXPECT HIGHS TO STAY IN THE MID TO
UPPER 80S TOWARD I-70. A FEW THUNDERSTORMS COULD DEVELOP OR MOVE
INTO WEST CENTRAL KANSAS LATE THURSDAY AFTERNOON OR EVENING. NOT
REAL CONFIDENT IN THIS YET SO WILL JUST GO WITH LESS THAN 15
PERCENT POPS FOR THAT AREA AT THIS TIME.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 320 PM CDT WED MAY 2 2012
MEDIUM RANGE MODELS INDICATE AN UPPER LEVEL TROUGH OF LOW PRESSURE
PUSHING ASHORE INTO THE PACIFIC NORTHWEST FRIDAY THEN CONTINUING TO
TRACK EASTWARD ACROSS THE NORTHERN ROCKIES SATURDAY, AND INTO THE
NORTHERN PLAINS ALONG THE CANADIAN BORDER BY THE END OF THE WEEKEND.
THIS SYSTEM WILL BRING THE POSSIBILITY FOR SHOWERS AND THUNDERSTORMS
FROM THE NORTHERN PLAINS SOUTHWARD INTO PORTIONS OF NEBRASKA AND
KANSAS THROUGHOUT THE WEEKEND. AN ATTENDANT COLD FRONT TO THE UPPER
LEVEL SYSTEM IS PROGGED TO PUSH SOUTHEAST INTO WESTERN KANSAS
SOMETIME EARLY SUNDAY SETTING UP THE CHANCE FOR PRECIP ACROSS
PORTIONS OF WESTERN KANSAS BY LATE SUNDAY INTO EARLY MONDAY.
ALTHOUGH MODELS BEGIN TO DIVERGE EARLY NEXT WEEK, ALL SHOW UPPER
LEVEL TROUGHING DEEPENING ACROSS THE INTERMOUNTAIN WEST SETTING UP A
SOUTHWESTERLY FLOW ALOFT ACROSS THE WESTERN HIGH PLAINS. MEANWHILE,
A SERIES OF H5 VORT MAXES ARE LIKELY TO EJECT NORTHEAST OUT OF THE
TROUGH, AND ALONG WITH PLENTY OF LOW LEVEL MOISTURE AVAILABLE,
INCREASE CHANCES FOR PRECIP VIRTUALLY EACH DAY THROUGH THE END OF
THE PERIOD.
TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL FRIDAY AS UPPER LEVEL
TROUGHING BEGINS TO PUSH EAST ACROSS THE INTERMOUNTAIN WEST. AS THE
UPPER LEVEL SYSTEM APPROACHES FROM THE WEST, A SURFACE TROUGH LEE OF
THE ROCKIES WILL HELP INFLUENCE A LOW LEVEL SOUTH TO SOUTHWESTERLY
FLOW ACROSS WESTERN KANSAS. THIS WILL ENHANCE WARM AIR ADVECTION
INTO THE AREA WITH H85 TEMPERATURES RANGING FROM THE MID 20S(C)
ACROSS CENTRAL KANSAS TO THE UPPER 20S(C) NEAR THE COLORADO BORDER.
SO, WITH THE NAM, GFS, AND GEM SHOWING DRY LAPSE RATES IN THE LOWER
LEVELS, LOOK FOR HIGHS UP INTO THE LOWER TO MID 90S(F) FRIDAY
AFTERNOON. SIMILAR HIGHS ARE LIKELY SATURDAY WITH LEE SIDE TROUGHING
PERSISTING NEAR THE COLORADO BORDER AND H85 TEMPERATURES CHANGING
VERY LITTLE. GENERALLY COOLER TEMPERATURES ARE THEN EXPECTED SUNDAY
AS A COLD FRONT IS PROJECTED TO PUSH INTO WESTERN KANSAS SOMETIME
DURING THE DAY ALLOWING COOLER AIR TO FILTER SOUTH INTO WESTERN
KANSAS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1200 AM CDT THU MAY 3 2012
MVFR CIGS ARE INDICATED BY MOS GUIDANCE AS WELL AS THE 01Z HRRR FOR
KHYS IN ASSOCIATION WITH WITH POST FRONTAL UPSLOPE STRATUS. THE RELATED
FRONT WILL MOVE THROUGH KGCK AND KDDC EARLY IN THE MORNING AS WELL,
HOWEVER, ENOUGH MIXING LOOKS TO KEEP CIGS AT VFR. THIS FRONT WILL STALL
OUT THROUGH THE DAY AND RETURN NORTH AS A WARM FRONT BY EVENING. WINDS
SHOULD GENERALLY BE LIGHT (8 TO 13 KT) WITH A GRADUAL VEERING IN DIRECTION
WITH THE RETURN OF THE WARM FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 60 91 60 95 / 0 10 10 0
GCK 55 89 56 94 / 0 10 10 0
EHA 54 90 57 93 / 0 0 0 0
LBL 56 92 58 96 / 0 10 0 0
HYS 61 85 60 93 / 0 10 10 0
P28 66 92 64 92 / 0 10 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GERARD
LONG TERM...JJOHNSON
AVIATION...SUGDEN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1226 AM CDT THU MAY 3 2012
.AVIATION...06Z KGRI TAF. THUNDERSTORM CHANCES REMAIN A CONCERN
FOR THE TAF PERIOD THROUGH THE NEXT FEW HOURS. THUNDERSTORMS HAVE
BEEN DEVELOPING ALONG AND NORTH OF AN OUTFLOW BOUNDARY. THESE
STORMS HAVE BEEN CAPABLE OF PRODUCING HAIL UP TO 2 INCHES IN
DIAMETER. WHILE SOUTH SOUTHEAST WINDS ARE EXPECTED DURING THE
OVERNIGHT HOURS...ANY THUNDERSTORMS THAT DEVELOP COULD PROVIDE THE
POTENTIAL FOR STRONG GUSTS OVER THE TAF SITE. BY THE EARLY MORNING
HOURS...WINDS WILL BECOME LIGHT AND VARIABLE.
&&
PREV DISCUSSION... /ISSUED 345 PM CDT WED MAY 2 2012/
SHORT TERM...THROUGH 00Z FRIDAY. MORNING UPPER AIR ANALYSIS INDICATES
QUASI-ZONAL MID AND UPPER LEVEL FLOW ACROSS MUCH OF THE CENTRAL
CONUS...WITH A MID LEVEL SHORTWAVE TROUGH NOTED OVER THE
NORTHWESTERN CONUS. MID AND UPPER LEVEL JET ENERGY REMAINS
RELEGATED TO THE WEST/NORTHWESTERN CONUS...WITH TROPOSPHERIC FLOW
REMAINING FAIRLY LIGHT OVER OUR AREA. WATER VAPOR IMAGERY
INDICATES A PLUME OF MID LEVEL MOISTURE ADVANCING FROM THE PACIFIC
INTO THE SOUTHWESTERN CONUS...ONWARD INTO THE MIDDLE ROCKY
MOUNTAIN RANGE AS WELL AS PORTIONS OF THE CENTRAL AND NORTHERN
PLAINS. EARLY AFTERNOON SURFACE ANALYSIS SHOWS AN AREA OF LOW
PRESSURE OVER SOUTHWESTERN KANSAS...WITH A WARM FRONT EXTENDING
NORTHEASTWARD FROM THE LOW INTO PORTIONS OF NORTH CENTRAL KANSAS
AS WELL AS PORTIONS OF SOUTH CENTRAL AND SOUTHEAST NEBRASKA. AS OF
18Z THIS WARM FRONT WAS NOTED EXTENDING FROM NEAR KHYS...TO NEAR
KK82...TO NEAR KJYR AND KOLU. EARLY AFTERNOON TEMPERATURES ARE
GENERALLY IN THE UPPER 70S AND LOWER 80S ACROSS THE CWA...WITH DEW
POINTS RANGING FROM THE MID 40S AT KLXN...TO THE UPPER 50S THROUGH
THE TRI-CITIES...TO THE MID AND UPPER 60S ACROSS OUR SOUTHEAST
WHERE THE SURFACE WARM FRONT HAS ALREADY CLEARED. EARLY AFTERNOON
VISIBLE SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES ACROSS OUR
NORTHWESTERN CWA...WITH THE INCREASED LOW LEVEL MOISTURE VALUES
HELPING PROMOTE INCREASED INSTABILITY AND A RESULTANT EXPANSIVE CU
FIELD.
FOR THE REST OF THIS AFTERNOON AND EARLY THIS EVENING...CONFIDENCE
IS LOW REGARDING CONVECTIVE DEVELOPMENT ACROSS OUR AREA AS FORECAST
PROXIMITY SOUNDINGS FROM THE NAM AND OPERATIONAL GFS SUGGEST
CONVECTIVE INHIBITION SHOULD HOLD FOR THE MOST PART. THAT BEING
SAID...FORECAST PROXIMITY SOUNDINGS FROM THE NAM DO SUGGEST CIN WILL
DECREASE TO ALMOST NOTHING ACROSS OUR EXTREME SOUTHEAST BY 00Z THIS
EVENING...AND WITH THE LOW LEVEL BAROCLINIC ZONE MEANDERING ACROSS
THE AREA THUS PROMOTING LOW LEVEL CONVERGENCE AND RESULTANT
FORCING...FELT IT PRUDENT TO GO WITH A SLIGHT CHANCE POP ACROSS THE
ENTIRE CWA LATE THIS AFTERNOON THROUGH THIS EVENING. THE NAM AND
OPERATIONAL GFS SUGGEST 0-1KM MLCAPE VALUES OF 2000-3500J/KG WILL BE
OBSERVED ACROSS OUR CWA LATE THIS AFTERNOON AND EVENING...WITH THE
GREATEST INSTABILITY LOCATED ACROSS OUR SOUTHEAST WITHIN THE LOW
LEVEL MOISTURE PLUME. WITH MID AND UPPER LEVEL JET ENERGY REMAINING
RELEGATED TO THE WEST/NORTHWEST OF OUR AREA...DEEP LAYER BULK SHEAR IS
NOT OVERLY IMPRESSIVE...BUT GUIDANCE DOES SUGGEST DEEP LAYER BULK
SHEAR VALUES NEAR 30KTS WILL STILL BE POSSIBLE THUS PRESENTING THE
POSSIBILITY FOR ROTATING UPDRAFTS. ALL THAT BEING SAID...SHOULD
CONVECTIVE INITIATION BE REALIZED LATE THIS AFTERNOON OR EARLY THIS
EVENING...SEVERE WEATHER WILL MOST LIKELY BE OBSERVED WITH LARGE
HAIL BEING THE PRIMARY THREAT...AND ISOLATED THUNDERSTORM WIND GUSTS
ALSO POSSIBLE ALONG OUTFLOW. FINALLY...0-1KM SRH IS NOT OVERLY
IMPRESSIVE...WITH THE NAM AND OPERATIONAL GFS SUGGESTING VALUES
SOMEWHERE AROUND 100 M^2/S^2 ACROSS OUR AREA AT 00Z...BUT WITH
LOCALLY ENHANCED LOW LEVEL HORIZONTAL VORTICITY EXISTING IN THE
VICINITY OF LOW LEVEL BAROCLINIC ZONE...ISOLATED TORNADOES ALSO
CANNOT BE RULED OUT.
ATTENTION THEN TURNS TO THE SEVERE POTENTIAL OVERNIGHT TONIGHT. THE
NAM...OPERATIONAL GFS...EC...SREF-MEAN AND HRRR ALL SUGGEST
AFTERNOON AND EVENING HIGH PLAINS CONVECTION WILL MORPH INTO A MCS
AND PUSH EAST INTO PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH
CENTRAL KANSAS. AS THE MCS PUSHES EAST IT SHOULD BEGIN INTERACTING
WITH A 40-50KT LOW LEVEL JET WHICH SHOULD HELP SUSTAIN THE MCS IF
NOT HELP IT INTENSIFY THROUGH INCREASED LOW LEVEL MOISTURE FLUX.
GIVEN ALL THIS...A WIDESPREAD SEVERE STRAIGHT LINE WIND EVENT
SOMEWHERE ACROSS OUR CWA IS APPEARING MORE AND MORE LIKELY OVERNIGHT
TONIGHT. AS IS USUALLY THE CASE...EXACT DETAILS REGARDING PLACEMENT AND
TRACK OF THIS MCS WILL NOT LIKELY BE KNOWN UNTIL LATER THIS
EVENING...BUT GIVEN THE LATEST DATA WILL GO AHEAD AND HIGHLIGHT MOST
ALL OF THE CWA FOR SEVERE OVERNIGHT TONIGHT...WITH STRAIGHT LINE
WINDS BEING THE PRIMARY SEVERE WEATHER THREAT. ONE ADDITIONAL
NOTE...THE AFOREMENTIONED MID LEVEL MOISTURE PLUME NOTED ON WATER
VAPOR IMAGERY SHOULD PUSH OVERHEAD TONIGHT THUS HELPING TO INCREASE
PRECIPITABLE WATER VALUES. THESE INCREASING MID LEVEL MOISTURE
VALUES...ALONG WITH THE STRONG CONVECTION CURRENTLY FORECAST...WILL
HAVE THE CAPABILITY TO PROMOTE HEAVY RAINFALL AND PERHAPS LOCALIZED
FLASH FLOODING.
PRECIPITATION CHANCES FOR THURSDAY REMAIN UNCERTAIN AT THIS
POINT...ESPECIALLY WITH THE POTENTIAL FOR A SIGNIFICANT MESO-HIGH
SETTING UP OVER THE AREA DUE TO OVERNIGHT RAIN. ASSUMING THE MESO-HIGH
CAN FULLY DISSIPATE BY MID TO LATE AFTERNOON...AND ASSUMING THERE
IS ENOUGH OMEGA WITH ONE OF THE MANY MID LEVEL PERTURBATIONS WHICH
WILL BE PUSHING OVER THE AREA ALONG THE APPROACHING MID LEVEL JET
AXIS...THURSDAY AFTERNOON 0-1KM MLCAPE VALUES ON THE ORDER OF
1000-2500J/KG COULD CERTAINLY PROMOTE A SEVERE HAIL THREAT. AT
THIS TIME IT APPEARS THE BEST POTENTIAL FOR OBSERVING SEVERE
WEATHER ON THURSDAY WILL BE RELEGATED TO OUR EAST WITHIN THE
BETTER LOW LEVEL MOISTURE...AND WILL GO AHEAD AND HIGHLIGHT OUR
EAST FOR SEVERE WEATHER ON THURSDAY AS A RESULT.
LONG TERM...STARTING WITH THE MID-TERM THURSDAY EVENING THROUGH
SATURDAY PERIOD...THE RISK OF THUNDERSTORMS...OR LACK
THEREOF...CONTINUES TO BE THE ULTIMATE DILEMMA DURING THESE 48
HOURS AND CONFIDENCE IN THE DETAILS CONTINUES TO RUN BELOW
AVERAGE. ALOFT...A BLEND OF SOLUTIONS FROM THE 12Z NAM/GFS AND 00Z
ECMWF CONTINUE TO ADVERTISE A RATHER PERSISTENT PATTERN...AS
MODESTLY STRONG...BROAD WEST-SOUTHWEST FLOW REMAINS IN
PLACE...DOWNSTREAM FROM A LARGER SCALE SHORTWAVE TROUGH THAT
CARVES OUT ACROSS THE PACIFIC NORTHWEST/NORTHERN ROCKIES. THE
PRIMARY 300MB JET AXIS WILL THUS REMAIN OFF TO THE NORTH AND WEST
OF THE REGION. HOWEVER...CONSIDERABLE CONVECTIVE INSTABILITY WILL
REMAIN FIRMLY IN PLACE IN OR NEAR THE CWA...AS A QUASI-STATIONARY
FRONT WAVERS BACK AND FORTH ACROSS THE GENERAL REGION. BEFORE
CONTINUING...WILL AGAIN STATE THAT CONFIDENCE IN THE DETAILS IS
LOW REGARDING POPS/THUNDER/SEVERE CHANCES...WITH A BIT HIGHER
CONFIDENCE IN TEMPS. HOWEVER...WAS NO LONGER WILLING TO LEAVE THE
FRIDAY THROUGH SATURDAY TIME FRAME COMPLETELY VOID OF ANY
THUNDERSTORM MENTION.
STARTING WITH THURSDAY EVENING/NIGHT...DECIDED TO BLANKET A GENERIC
20 PERCENT CHANCE OF STORMS CWA-WIDE...AS JUST CANNOT GUARANTEE A
STORM-FREE NIGHT ANYWHERE. DETERMINISTIC MODELS ARE ALL OVER THE
PLACE ON QPF PLACEMENT...WITH THE ECWMF ROLLING STORMS IN FROM THE
WEST MAINLY IN THE EVENING...WHILE THE NAM/GFS AFFECT AT LEAST
SOUTHWEST PORTIONS OF THE AREA MAINLY AFTER 06Z. LEANING ON THE 12Z
NAM...ONLY A MODEST LOW LEVEL JET IS PRESENT OVERNIGHT...BUT WITH
SUBTLE SHORTWAVES MOVING THROUGH AND HEALTHY ELEVATED MUCAPE IN
EXCESS OF 2500 J/KG HANGING OUT ACROSS MOST OF THE CWA THROUGH THE
NIGHT...JUST FEEL BETTER HAVING A TOKEN 20 PERCENT CHANCE
EVERYWHERE. HOWEVER...IT IS LIKELY THAT MOST OF THE AREA WILL IN
FACT REMAIN STORM FREE...WITH THE MOST LIKELY SCENARIO FOR POSSIBLE
CONVECTION BEING HIGH PLAINS ACTIVITY DRIFTING IN FROM THE WEST. AS
FOR SEVERE CHANCES THURSDAY NIGHT...DEEP LAYER SHEAR IS NOT ALL THAT
STRONG...20-30 KNOTS AT MOST...BUT OBVIOUSLY WITH HIGH CAPE LEVELS
HANGING AROUND CANNOT RULE OUT AT LEAST MARGINALLY SEVERE HAIL AND
WIND. AS FOR LOW TEMPS...NUDGED UP SLIGHTLY FROM PREVIOUS
FORECAST...WITH MOST OF SOUTHEAST 1/2 OF CWA HOLDING UP IN THE
LOW-MID 60S.
FOR FRIDAY...MUCH OF THE SAME...AS FORCING ALOFT REMAINS
SUBTLE...BUT INSTABILITY REMAINS HIGH WITH AFTERNOON MLCAPE VALUES
AGAIN BUILDING TO AROUND 3000 J/KG OR HIGHER PER THE NAM...ALTHOUGH
THIS MODEL MAY BE OVERDOING DEWPOINTS AND RESULTANT CAPE A BIT.
ALTHOUGH ODDS ARE REASONABLY HIGH THAT MOST OF THE AREA WILL REMAIN
STORM FREE...OPTED TO INTRODUCE A SLIGHT 20 POP ACROSS SEVERAL
COUNTIES NORTH OF I-80...AS HINTED AT BY THE 12Z GFS AND TO A LESSER
EXTENT THE 12Z NAM. AGAIN...ANYTHING THAT HAPPENS TO FIRE IN THIS
AREA BEFORE DARK COULD POTENTIALLY BE SEVERE. TEMP WISE...ASSUMING
THAT SOUTHERLY BREEZES ARE PRESENT AND CLOUDS ARE NOT
WIDESPREAD...THIS HAS THE POTENTIAL TO BE A RATHER WARM DAY.
ALTHOUGH STILL NOT AIMING QUITE AS HIGH AS THE NAM SUGGESTS...NUDGED
UP A FEW DEGREES...NOW PUTTING MOST OF THE CWA IN THE 87-90 RANGE.
FRIDAY NIGHT...INTRODUCED MORE SLIGHT THUNDERSTORM CHANCES MAINLY
NORTH OF I-80 IN CLOSEST PROXIMITY TO TRACK OF SUBTLE
SHORTWAVES...AND IN THE PRESENCE OF CONTINUED HEALTHY ELEVATED
INSTABILITY. FOR THE DAYTIME HOURS SATURDAY...JUST CONTINUED WITH
MORE OF THE SAME...KEEPING THE SAME AREAS NORTH OF INTERSTATE 80 IN
A SLIGHT CHANCE OF STORMS...BUT WITH BETTER FOCUS LIKELY TARGETING
AREAS JUST TO THE NORTH. BY THIS TIME...THE PRIMARY MID LEVEL TROUGH
TO THE WEST WILL BE CENTERED ROUGHLY ALONG A MT-UT AXIS...BUT STILL
WELL TO THE WEST. TEMP WISE SATURDAY...KEPT SUMMER-LIKE READINGS
GOING AND EVEN NUDGED UP A FEW DEGREES FROM PREVIOUS PER MODEL
CONSENSUS...WITH MID-UPPER 80S MOST AREAS...AND SOME LOW 90S MOST
FAVORED IN KS ZONES.
FOCUSING NOW ON THE LONGER TERM PERIODS SATURDAY NIGHT THROUGH
NEXT WEDNESDAY: IN SHORT...EACH AND EVERY PERIOD FEATURES AT LEAST
20-30 PERCENT RAIN CHANCES FOR NOW...ALTHOUGH WILL STATE THE OBVIOUS
THAT SOME OF THESE PERIODS WILL LIKELY END UP BEING DRY...WITH
PLENTY OF TWEAKING LIKELY OVER THE NEXT SEVERAL DAYS. LOOKING AT THE
BIG PICTURE AND LEANING TOWARD A BLEND OF THE 12Z ECMWF/GFS...THERE
IS ACTUALLY REASONABLY HIGH AGREEMENT THAT ON SATURDAY NIGHT AND
SUNDAY NIGHT A FAIRLY WELL DEFINED SURFACE COLD FRONT WILL CROSS THE
AREA...DRIVEN SOUTHWARD IN RESPONSE TO THE AFOREMENTIONED MID LEVEL
SHORTWAVE TROUGH RIDING UP ACROSS THE NORTHERN PLAINS INTO SOUTH
CENTRAL CANADA. AS A RESULT OF THIS FRONTAL PASSAGE...THE HIGHEST
POPS IN THE EXTENDED PERIOD...40S-50S PERCENTS ACROSS MAINLY NEB
ZONES FOR NOW...ARE FOCUSED ON SATURDAY NIGHT. ALTHOUGH DEEP LAYER
WIND SHEAR DOES NOT LOOK OVERLY IMPRESSIVE WITH THIS FRONTAL
PASSAGE...THE GFS HAS MUCAPE VALUES OF AT LEAST 2000-3000 J/KG IN
PLACE DURING THIS TIME FRAME...SO CERTAINLY A SLIGHT RISK OF SEVERE
NOT OUT OF THE QUESTION. IN THE WAKE OF THIS BOUNDARY...TEMPS SUNDAY
ARE CURRENTLY FORECAST ABOUT 10 DEGREES COOLER THAN
SATURDAY...RANGING FROM LOW 70S NORTHWEST TO LOW 80S SOUTHEAST.
BEYOND SUNDAY...THE CURRENTLY ADVERTISED POPS WOULD SEEM TO COME
MORE AND MORE UNDER QUESTION...BUT WILL STICK WITH THEM PER NOW
ACCORDING TO THE ALLBLEND CONSENSUS INITIALIZATION. THE BASIC STORY
INVOLVES A GRADUAL CARVING OUT OF A MID LEVEL TROUGH ACROSS THE
NORTH CENTRAL CONUS...RESULTING IN A NOTICEABLY COOLER TEMP REGIME
THAN THE CURRENT PATTERN. NUDGED DOWN HIGHS SLIGHTLY FOR MONDAY WITH
UPPER 60S-LOW 70S...WHILE TUESDAY CONTINUES TO LOOK LIKE THE COOLEST
DAY OF THE PERIOD WITH HIGHS ONLY MID-UPPER 60S ALL AREAS AND MAYBE
A REBOUND TO NEAR 70 WEDNESDAY. EVEN IF RAIN WERE TO MATERIALIZE
DURING THE MONDAY NIGHT-WEDNESDAY TIME FRAME...HAVE DROPPED THUNDER
MENTION IN THE FORECAST IN FAVOR OF PLAIN SHOWERS...AS MUCAPE PROGS
FROM BOTH THE ECMWF/GFS ADVERTISE VERY LIMITED IF ANY CONVECTIVE
INSTABILITY. IN CLOSING...WANT TO REITERATE THAT ALTHOUGH POPS IN
THE SAT NIGHT-SUNDAY TIME FRAME LOOK QUITE WARRANTED...WOULD EXPECT
TO SEE AN EVENTUAL TRIMMING OF SOME OF THE RAIN CHANCES DURING THE
SUNDAY NIGHT-WEDNESDAY TIME FRAME.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
140 AM EDT THU MAY 3 2012
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL PASS THROUGH THE GREAT LAKES
TONIGHT. HIGH PRESSURE WILL STRENGTHEN ON THURSDAY...LEADING TO
MAINLY DRY WEATHER AND CONTINUED MUCH ABOVE NORMAL TEMPERATURES. A
COLD FRONT WILL SLOWLY SINK SOUTH INTO THE REGION THROUGH THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATED THE FORECAST TO DECREASE PRECIPITATION CHANCES FOR THE
OVERNIGHT TIME FRAME. THE HRRR IS STILL TRYING TO SHOW A FEW
STORMS DEVELOPING AND MOVING ACROSS EXTREME NORTHERN PORTIONS OF
THE FA. MODELS HAVE BEEN OVERDOING PRECIPITATION TONIGHT AND
CURRENTLY DRY CONDITIONS ARE PRESENT ACROSS THE REGION. ONLY LEFT
A SLIGHT CHANCE OF THUNDERSTORMS IN ACROSS THE EXTREME NORTHERN
LOCATION OF THE FA HOWEVER BELIEVE THE CHANCE FOR PRECIPITATION
WILL BE LOW. MADE MINOR ADJUSTMENTS TO TEMPERATURES TO ACCOUNT FOR
CURRENT TRENDS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
UPPER LEVEL RIDGING WILL STRENGTHEN ON THURSDAY WHICH SHOULD PUT A
MORE SUBSIDENT ATMOSPHERE IN PLACE...ALTHOUGH A DECENT AMOUNT OF
INSTBY WILL CONTINUE TO BE PRESENT. SOME MODELS TRY TO POP A FEW
STORMS BUT THINK THIS THREAT IS PRETTY MINIMAL. WITH GOOD
MIXING...THERE WILL BE SOME CUMULUS DEVELOPMENT BUT STILL PLENTY
OF SUN AND WAA...SO EXPECT ANOTHER DAY OF TEMPERATURES IN THE MID
80S AND PERHAPS UPPER 80S IN THE SE. RECORD HIGHS ARE 87 AT
CVG...89 AT CMH...AND 90 AT DAY. IT WILL BE A LITTLE BREEZY AS
WELL...PARTICULARLY THE NW WHERE A TIGHTER PRESSURE GRADIENT WILL
BE DUE TO LOW PRESSURE OVER THE UPPER GREAT LAKES.
THERE IS SOME MODEL DISAGREEMENT ON WHAT TO DO WITH AN EMBEDDED
VORT MAX OVER THE GULF COAST. THE NAM/GFS TRY TO LIFT THIS ALL THE
WAY INTO WEST VIRGINIA BY THURSDAY EVENING AND OVERNIGHT...WHICH
COULD PROVIDE SOME PCPN TO OUR FAR SE COUNTIES. OTHER MODELS ARE
WEAKER WITH THIS FEATURE AND MAINLY KEEP ITS INFLUENCE OUT OF OUR
AREA. FOR NOW JUST INTRODUCED LOW END POPS IN THE SE DURING
THIS PERIOD. OTHERWISE ANOTHER NIGHT WITH LOWS IN THE MID 60S IS
IN STORE.
HEIGHTS BEGIN TO FALL ON FRIDAY. MODELS ARE IN PRETTY GOOD
AGREEMENT ON BRINGING A SHORTWAVE TROUGH THROUGH THE GREAT LAKES
DURING THE DAY...WHILE A SFC BOUNDARY SLOWLY SINKS SOUTH AS WELL.
DEEP MOISTURE WILL BE ON THE INCREASE...SO EXPECT MORE CLOUDS AND
SHOWERS AND THUNDERSTORMS GRADUALLY WORKING THEIR WAY SOUTH INTO
THE AREA. SHEAR PROFILES WILL ALSO BECOME MORE FAVORABLE WHICH
COULD LEAD TO SOME SEVERE STORMS. THIS IS HIGHLIGHTED IN THE HWO
AND SPC DAY 3 OUTLOOK. ABOVE FACTORS WILL LIMIT DAYTIME HIGHS TO
THE LOWER TO MID 80S. THE NORTH COULD BE COOLER IF STORMS MOVE IN
EARLY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
SATURDAY STARTS OUT WITH THE PREDAWN HOURS AND A FRONT DRAPED W-E
OVER THE OHIO VALLEY PROVIDING A FOCUS FOR EXPECTED SHOWER AND
THUNDERSTORMS. THESE STORMS MAY CONTINUE INTO SATURDAY DAYLIGHT
HOURS AS THE FRONT CONTINUES TO SAG SOUTHWARD TOWARDS THE LOWER OHIO
VALLEY OR NORTHERN TENNESSEE VALLEY. THIS PUSH IS DUE TO BUILDING
HIGH PRESSURE OVER CANADA NORTH OF THE GREAT LAKES.
MODELS DIFFER IN THEIR RESULTS ON SUNDAY BUT THE EUROPEAN DEVELOPS A
WARM FRONT OVER CWA WHILE CANADIEN AND GFS CONTINUE TO BUILD THE
HIGH TO THE NORTHEAST...KEEPING A MORE DRY EASTERLY FLOW OVER CWA
THROUGH SUNDAY AND SUN NIGHT. LOW PRESSURE WILL DEVELOP OVER THE
MIDWEST ON MONDAY AND TRACK TOWARDS THE OHIO VALLEY DURING THE
DAY...COMBINING WITH THE BREAKDOWN OF THE UPPER RIDGE TO INCREASE
THE CHANCE FOR ANOTHER ROUND OF STORMS MONDAY AND MONDAY NIGHT.
THE RESULTANT COLD FRONT CROSSES EARLY TUESDAY AND DRIER AIR SHOULD
REPLACE IT THROUGH MID WEEK AS HIGH PRESSURE BUILDS BEHIND IT WITH
COOLER AND DRIER AIR.
TEMPERATURES THROUGH TUESDAY WILL CONTINUE TO BE UNSEASONABLY WARM
IN THE UPPER 70S TO LOWER 80S WITH MILD NIGHTTIME LOWS IN 55-60
RANGE. AFTER TUESDAY THERE SHOULD BE A BIT COOLER AIR FILTERING
IN...MAKING READINGS MORE TOWARDS SEASONAL NORMALS.
CONFIDENCE IN THE EXTENDED BEYOND SATURDAY REMAINS LOW DUE TO THE
LARGE VARIABILITY IN MODEL GUIDANCE AND RUN TO RUN INCONSISTENCY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AN UPPER LEVEL LOW OVER THE SOUTHERN STATES WILL DRIFT NORTHWARD
TOWARD THE TENNESSEE VALLEY THIS AFTERNOON. IT WILL THEN WEAKEN AS
IT SHIFTS NE INTO THE MID/UPPER OHIO VALLEY TONIGHT.
MEANWHILE...THE WESTERN GREAT LAKES WILL REMAIN UNDER A BROAD SW
FLOW ALOFT WITH EMBEDDED DISTURBANCES RIPPLING THROUGH IT FROM
TIME TO TIME. OUR REGION WILL BE WEDGED BETWEEN THESE TWO WEATHER
FEATURES AND SHOULD REMAIN DRY THROUGH THE TAF PERIOD AS
CONVECTION IS EXPECTED TO REMAIN NW AND SE OF THE TAF SITES.
THIS PATTERN WILL RESULT IN VFR CONDITIONS...EXCEPT KLUK...WHERE
SOME RIVER FOG MAY RESULT IN SOME MVFR VSBYS UNTIL 13Z. SOUTH TO
SOUTHWEST WINDS WILL BECOME LOCALLY GUSTY UP TO 25 KNOTS BETWEEN
16Z AND 00Z...DIMINSIHING THIS EVENING AS THE LOW LEVELS DECOUPLE.
OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY...SATURDAY AND AGAIN ON
MONDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...NOVAK
SHORT TERM...SNYDER
LONG TERM...FRANKS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION...UPDATE
NWS MILWAUKEE/SULLIVAN WI
417 AM CDT THU MAY 3 2012
.TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
TRAINING MULTICELLULAR TSTORMS IS SLOWLY DECREASING IN COVERAGE AND
INTENSITY OVER THE FAR NRN CWA AND SHOULD BE CLOSE TO ENDING BY
SUNRISE OR SHORTLY AFTER AS THE LOW LEVEL JET STREAM FOCUSES MORE TO
THE NORTHEAST. A WEAK MCS OVER IA IS PROGRESSING TOWARD SRN WI
WITHIN THE MEAN FLOW WITH THE HRRR MODEL BRINGING IT ACROSS THE CWA
FROM 14Z TO 19Z. WENT WITH THIS SCENARIO. AFTERWARD BELIEVE THE MAIN
FOCUS FOR CONVECTION WILL BE TOWARD THE IL BORDER AND SWD DUE TO THE
STABILIZING EFFECTS OF THE CONVECTION...AND ALSO WITH THE MAIN FOCUS
OF THE LLJ AND ANY WEAK SHORTWAVE TROUGHS TO OUR SOUTH. THUS ONLY
HAVE CHANCE POPS FOR LATE AFTERNOON THROUGH TNT.
A GOOD PORTION OF MQT...GREEN LAKE COUNTIES HAVE RECEIVED
APPROXIMATELY 3-4 INCHES OF RAIN BUT ONLY MINOR FLOODING HAS BEEN
REPORTED DUE TO THE MANY AREAS OF MARSHES AND LAKES ACTING AS A
SINK. THIS AREA WILL STILL BE MORE SUSCEPTIBLE TO FLOODING BUT
CONFIDENCE FOR FLASH FLOODING IS TOO LOW TO ISSUE A WATCH AND
BELIEVE THIS AREA CAN HANDLE ANOTHER INCH OR LESS OF RAIN WITHOUT
FLASH FLOODING OCCURRING.
.FRIDAY...FORECAST CONFIDENCE...MEDIUM
SURFACE FRONT EXPECTED TO GENERALLY BE NEAR THE WI/IL BORDER FRIDAY
MORNING...THOUGH THERE ARE MODEL DIFFERENCES AND THURSDAY NIGHT
CONVECTION WILL PROBABLY HAVE A SAY ON THE LOCATION OF THE
BOUNDARY BY MORNING. KEPT SOME POPS GOING THROUGH THE DAY
FRIDAY...THE BEST CHANCE SOUTH TOWARD THE FRONT. NAM AND GFS
SUPPORT POPS MORE THAN THE ECMWF AND CANADIAN...WITH THE FRONT
FARTHER NORTH THAN THE LATTER MODELS. THE NAM AND GFS WOULD ALSO
BE WARMER...THOUGH TEMPS SEEM A BIT OVERDONE GIVEN SFC FEATURES.
SIZABLE TEMP DIFFERENCES BETWEEN THE TWO SOLUTIONS...SO GENERALLY
SPLIT THE DIFFERENCE. WILL BE COOLER TOWARD THE LAKE UNDER
NORTHEAST WINDS.
.SATURDAY THOUGH MONDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
MODELS GENERALLY KEEP THE BAROCLINIC ZONE IN THE AREA FOR SATURDAY
AND SUNDAY...PUSHING LOW PRESSURE THOUGH SUNDAY NIGHT INTO MONDAY.
FELT THE NEED TO KEEP POPS GOING THROUGH THE WEEKEND WITH A COUPLE
IMPULSES RIDING THROUGH THE FLOW. BEST CHANCE FOR PRECIP WILL BE
SUNDAY NIGHT AND MONDAY AS THE LOW SLIDES THOUGH. MODEL SOUNDINGS
CONTINUE TO SHOW SOME CAPE THROUGH MONDAY...SO KEPT THUNDER
MENTION WITH PRECIP. MODELS CONTINUE TO BOUNCE AROUND A BIT WITH
TEMPS FOR THE WEEKEND AND MONDAY...AS THE BAROCLINIC ZONE SHIFTS
SOME FROM RUN TO RUN. THUS GENERALLY WENT WITH CONSENSUS OF MODEL
TEMPS...RESULTING IN NEAR NORMAL VALUES. WILL BE COOLER NEAR LAKE
MICHIGAN WITH PERSISTENT ONSHORE FLOW.
TUESDAY AND WEDNESDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
UPPER TROUGH TO APPROACH TUESDAY...MOVING THROUGH TUESDAY NIGHT OR
WEDNESDAY. THUS MORE SHOWER CHANCES EXPECTED...WITH MAYBE A FEW
RUMBLES OF THUNDER. NEAR NORMAL TEMPS ANTICIPATED TO CONTINUE
THROUGH THE FIRST HALF OF THE WEEK.
&&
.AVIATION/12Z TAFS/...MAINLY VFR CONDITIONS ARE EXPECTED TODAY AND
TONIGHT BUT THUNDERSTORMS ARE LIKELY FROM LATE THIS MORNING INTO THE
EARLY AFTERNOON WITH THE POTENTIAL FOR THUNDERSTORMS TO CONTINUE
TONIGHT. MVFR TO IFR CONDITIONS WILL OCCUR WITHIN THE THUNDERSTORMS
AND MAY LINGER IN THEIR WAKE AS WELL.
.MARINE...WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA BUT MOIST AIR FLOWING OVER THE COLD WATERS OF LAKE MICHIGAN
MAY RESULT IN FOG...AT TIMES DENSE...FOR TODAY AND TONIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
FRIDAY THROUGH WEDNESDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
346 AM CDT THU MAY 3 2012
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
346 AM CDT THU MAY 3 2012
FORECAST CONCERNS FOR TODAY ARE CENTERED ON SHOWER AND THUNDERSTORM
CHANCES WITH THE POSSIBILITY OF SEVERE THUNDERSTORMS. FOCUS THEN
TURNS TO SHOWER/THUNDERSTORM CHANCES FRIDAY AFTERNOON THROUGH THIS
WEEKEND.
CURRENT RADAR IMAGERY SHOWED A CLUSTER OF SHOWERS AND
THUNDERSTORMS ACROSS ADAMS AND JUNEAU COUNTIES EARLY THIS
MORNING...PRODUCING BRIEF HEAVY DOWNPOURS. AT 330 AM RADAR SHOWED
A LINE OF STRONG TO SEVER THUNDERSTORMS PUSHING INTO FAR NORTHWEST
WISCONSIN...BURNETT AND POLK COUNTIES...MOVING EAST. WILL HAVE TO
KEEP A CLOSE WATCH ON THIS LINE OF STORMS THIS MORNING SINCE THEY
HAVE TO POTENTIAL TO IMPACT CLARK AND TAYLOR COUNTY BETWEEN 6 AM
AND 7 AM.
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE ONGOING EARLY THIS
MORNING. ANOTHER ROUND OF STRONG TO POTENTIALLY SEVERE THUNDERSTORMS
ARE POSSIBLE THIS AFTERNOON....ESPECIALLY ACROSS NORTHEAST IOWA INTO
FAR SOUTHWEST WISCONSIN. AN UNSTABLE AIRMASS WILL REMAIN IN PLACE
ACROSS THE FORECAST AREA TODAY...WITH MUCAPE VALUES OF 1500 TO 2000
J/KG. 0-6 KM BULK SHEAR VALUES WILL RANGE FROM 35 TO 40 KTS THROUGH
THE MID AFTERNOON HOURS...THEN START TO WANE IN THE LATE AFTERNOON
AND EVENING HOURS AS MID LEVEL WINDS DECREASE. THERE THE POTENTIAL
FOR A FEW STRONG TO SEVERE THUNDERSTORMS TODAY WITH THE MAIN THREATS
BEING LARGE HAIL...DAMAGING WINDS...AND HEAVY RAINFALL. AN
OUTFLOW/FRONTAL BOUNDARY JUST NORTH OF THE INTERSTATE 90 CORRIDOR
WILL SHIFT SOUTH INTO NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN
THIS AFTERNOON INTO THIS EVENING. THIS BOUNDARY WILL BE TH FOCUS FOR
THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON INTO THIS EVENING...WITH
THE POTENTIAL FOR SEEING A FEW ROUNDS OF STORMS ALONG IT. THIS MAY
LEAD TO HEAVY RAIN CONCERNS ACROSS PORTIONS OF NORTHEAST IOWA AND
FAR SOUTHWEST WISCONSIN WITH PRECIPITABLE WATER VALUES AROUND 200
PERCENT OF NORMAL...WARM CLOUD DEPTHS OF 3500 METERS. WILL HAVE TO
KEEP A CLOSE WATCH ON THE PROGRESSION OF THE BOUNDARY TODAY. IF
CONVECTION FIRES THIS AFTERNOON ACROSS SOUTHEAST MINNESOTA INTO WEST
CENTRAL WISCONSIN...THE BOUNDARY MAY END UP BEING PUSHED SOUTH OF
THE FORECAST AREA. THE SHOWERS AND THUNDERSTORMS SHOULD MOVE SOUTH
AND EAST OF THE FORECAST AREA LATE IN THE EVENING WITH A BREAK IN
PRECIPITATION CHANCES FOR MUCH OF THE FORECAST AREA FROM LATE
TONIGHT THROUGH MIDDAY FRIDAY.
A SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS SOUTH DAKOTA AND PUSH
INTO CENTRAL/SOUTHERN MINNESOTA FRIDAY AFTERNOON. THIS FEATURE LOOKS
TO MOVE EAST INTO THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY AFTERNOON
INTO FRIDAY NIGHT BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS TO
THE AREA...SOME WHICH COULD POSSIBLY BE SEVERE. 0-6 KM BULK SHEAR OF
40 TO 50 KTS...AND 0-3KM MUCAPE VALUES OF NEARLY 3000 J/KG WILL MORE
MORE THAN SUFFICIENT TO SUPPORT SEVERE THUNDERSTORMS. SUPERCELLS
WITH LARGE HAIL AND DAMAGING WINDS APPEAR POSSIBLE BUT THERE ARE
STILL SOME DETAILS THAT NEED TO BE WORKED OUT. ONE OF THE MAIN
CONCERNS IS HOW MUCH CLOUD COVER WILL BE AROUND THE REGION WHICH
WILL GREATLY IMPACT THE AMOUNT OF INSTABILITY. PLAN ON HIGHS ON
FRIDAY RANGING FROM THE UPPER 60S ACROSS NORTH CENTRAL WISCONSIN TO
THE UPPER 70S TO AROUND 80 ACROSS NORTHEAST IOWA. SHOWERS AND
THUNDERSTORM CHANCES WILL CONTINUE THROUGH FRIDAY NIGHT. THE ACTIVE
PATTERN IS EXPECTED TO PERSIST SATURDAY INTO SATURDAY NIGHT WITH
CONTINUED CHANCES FOR SHOWERS AND THUNDERSTORMS. THE EASTERN EXTENT
OF THE SHOWER/THUNDERSTORM CHANCES IS IN QUESTION AS HIGH PRESSURE
TRIES TO BUILD SOUTH OUT OF ONTARIO...THROUGH UPPER MICHIGAN INTO
CENTRAL WISCONSIN. THE HIGH MAKES A STRONG PUSH SATURDAY INTO
SUNDAY..WITH DEWPOINTS FALLING INTO THE MID 30S...POSSIBLY
LOWER...ACROSS NORTHERN WISCONSIN. WILL HAVE TO KEEP A CLOSE WATCH
ON THIS LOW LEVEL DRY AIR AS IT WILL GREATLY IMPACT PRECIPITATION
CHANCES.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
346 AM CDT THU MAY 3 2012
03.00 FORECAST MODELS IN GOOD AGREEMENT ON SUNDAY SHOWING A POTENT
TROUGH PUSHING ACROSS THE DAKOTAS EARLY SUNDAY MORNING THEN MOVING
INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION SUNDAY AFTERNOON.
THIS SYSTEM HAS THE POTENTIAL TO BRING ANOTHER ROUND OF SEVERE
WEATHER TO THE REGION...BUT IT IS A LITTLE TOO FAR OUT TO DETERMINE
THE EXACT DETAILS AND TIMING. THE TROUGH IS EXPECTED TO PUSH INTO
THE REGION MONDAY MORNING INTO TUESDAY BRINGING COOLER TEMPERATURES
TO THE AREA ALONG WITH CHANCES FOR SHOWERS AND PERHAPS AN ISOLATED
THUNDERSTORM. PLAN ON HIGHS IN THE 60S TO AROUND 70S ON
SUNDAY...FALLING INTO THE LOWER 60S ON MONDAY THROUGH WEDNESDAY. LOOK
FOR OVERNIGHT LOW TO FALL INTO THE 40S.
&&
.AVIATION...THROUGH 06Z FRIDAY
1212 AM CDT THU MAY 3 2012
RATHER COMPLICATED FORECAST FOR THIS TAF CYCLE WITH LOW
CONFIDENCE. MAIN PRECIPITATION AREA HAS MOVED EAST OF THE TAF
SITES...BUT STILL WARM ADVECTION OVER THE REGION KEEPING SCATTERED
SHOWERS/TSRA AROUND THE AREA THROUGH THE OVERNIGHT HOURS.
SHORTWAVE OVER EASTERN NEBRASKA TO TRANSLATE NORTHEAST OVERNIGHT.
03.00Z HRRR SHOWS CONVECTION WITH THIS WAVE TO LIFT ACROSS IOWA
OVERNIGHT ARRIVING IN THE TAF SITES AROUND DAYBREAK OR A LITTLE
AFTER. IN BETWEEN THIS...CEILINGS WILL LIKELY BE IN THE MVFR/IFR
CATEGORY OVERNIGHT WITH JUST SOME SCATTERED CONVECTION AROUND THE
AREA. DID RAISE CEILINGS LATER THURSDAY AS WAVE MOVES EAST OF THE
AREA. STILL SOME UNCERTAINTY WITH ADDITIONAL CONVECTIVE DEVELOPMENT
IN THE AFTERNOON. FOR NOW LEFT IT OUT AND WILL HAVE TO BE RE-
EVALUATED WITH LATER MODEL RUNS. VFR CONDITIONS THEN EXPECTED
AFTER 00Z.
&&
.HYDROLOGY...TODAY INTO TONIGHT
346 PM CDT WED MAY 2 2012
RAINFALL FROM LAST NIGHT THROUGH EARLY THIS MORNING RANGED FROM 1
TO 3 INCHES OVER NORTHERN WABASHA INTO CENTRAL BUFFALO COUNTY.
THIS ALONG WITH RAINFALL FROM TUESDAY NIGHT INTO WEDNESDAY MORNING
MAY PRODUCE SOME RIVER RISES. ADDITIONAL RAINFALL IS EXPECTED
TODAY WITH SOME LOCATIONS POSSIBLY RECEIVING 1/2 TO 1 INCH...WILL
HAVE TO KEEP A CLOSE EYE ON AREA STREAMS AND RIVERS FOR SOME
LOCALIZED FLOODING POTENTIAL.
HYDROLOGIC STATEMENTS HAVE BEEN ISSUED FOR SEVERAL RIVERS FOR THE
RISES THAT EITHER HAVE OCCURRED OR ARE EXPECTED TO OCCUR. PLEASE
REFERENCE THE LATEST STATEMENTS /MKERVSARX FGUS83/ FOR THE MOST
CURRENT INFORMATION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
346 AM CDT THU MAY 3 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....RABERDING
HYDROLOGY....WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1212 AM CDT THU MAY 3 2012
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
340 PM CDT WED MAY 2 2012
MAIN FORECAST CONCERNS WILL BE SEVERE WEATHER POTENTIAL THIS EVENING
AND OVERNIGHT/CONTINUING SHOWER AND THUNDERSTORM CHANCES THROUGH THE
REST OF THE PERIOD.
RUC/RAP SURFACE ANALYSIS THIS AFTERNOON HAS AN AREA OF LOW PRESSURE
NEAR GREAT BEND KS WITH A WARM FRONT EXTENDING ALONG I-70 ACROSS MO
INTO CENTRAL IL. MEANWHILE...RUC/RAP 1000-500MB THICKNESS ANALYSIS
SHOWS A FRONTAL BOUNDARY EXISTING ACROSS NORTHERN IA INTO SOUTHERN
WI...ALONG I-90. MEANWHILE...UNDER PARTLY TO MOSTLY SUNNY
SKIES...DESTABILIZATION IS TAKING PLACE MAINLY ALONG/SOUTH OF I-90.
CURRENT LAPS INDICATING 1000-2500J/KG 0-1KM MLCAPE ACROSS NORTHWEST
IA INTO SOUTHERN MN WITH 0-3KM BULK SHEAR IN THE 20-25KT RANGE. VIS
SATELLITE SHOWING INCREASING CUMULUS ALONG THE AFOREMENTIONED
FRONTAL BOUNDARY IN THIS DESTABILIZATION ZONE.
02.12Z NCEP MODEL SUITE/02.09Z SREF IN GENERALLY GOOD AGREEMENT
THROUGH THE SHORT TERM WITH HANDLING OF OVERALL SYNOPTIC SETUP.
MODELS SHOW INCREASING 925-850MB MOISTURE TRANSPORT INTO THE AREA
THIS EVENING AHEAD OF THE AREA OF LOW PRESSURE OVER THE CENTRAL
PLAINS. THIS MOISTURE TRANSPORT INTO THE FRONTAL BOUNDARY IS
EXPECTED TO TRIGGER A COMPLEX OF THUNDERSTORMS MAINLY ALONG AND
SOUTH OF I-94. WILL HAVE TO WATCH FOR SEVERE POTENTIAL THIS EVENING
AS THE NAM MAINTAINS 1500-2500J/KG 0-3KM MUCAPE AND BULK SHEAR IN
THE 20-35KT RANGE. IT APPEARS THE MAIN SEVERE THREATS GOING INTO
THIS EVENING WILL BE LARGE HAIL AND DAMAGING WINDS. CONVECTION LOOKS
TO WEAKEN SOME AFTER MIDNIGHT AS THE MOISTURE TRANSPORT AXIS BENDS
THE THE EAST OUT OF THE AREA AND CAPE WANES. ANOTHER CONCERN WILL BE
HEAVY RAIN POTENTIAL ACROSS PORTIONS OF NORTHEAST IA INTO FAR
SOUTHWEST WI AS PRECIPITABLE WATER VALUES INCREASE TO AROUND 1.5 TO
1.7 INCHES. WITH RECENT HEAVIER RAINFALL LAST NIGHT/EARLY THIS
MORNING AND LOW FLASH FLOOD GUIDANCE VALUES...WILL BE HOISTING A
FLASH FLOOD WATCH TONIGHT FOR PORTIONS OF NORTHEAST IA. HAVE ALSO
INCLUDED A HYDROLOGY SECTION BELOW TO DISCUSS HEAVY RAIN CONCERNS.
MODELS INDICATE FRONTAL/OUTFLOW BOUNDARY REMAINING NEARLY STATIONARY
ACROSS THE AREA THROUGH THURSDAY. NAM AND GFS SHOWING 0-3KM MUCAPE
INCREASING INTO THE 2000-3500J/KG RANGE BY THURSDAY AFTERNOON WITH
AMPLE BULK SHEAR. THIS CAPE HOWEVER WILL BE HIGHLY DEPENDENT ON HOW
MUCH CLEARING/HEATING CAN BE REALIZED BEHIND THE COMPLEX THAT ROLLS
THROUGH OVERNIGHT. FAIRLY DOUBTFUL WE WILL BE THAT CLEAN FOR THAT
MUCH DESTABILIZATION. WILL HAVE TO CONTINUE TO WATCH THIS CLOSELY
FOR SEVERE POTENTIAL IF WE DO REALIZE HIGHER CAPE.
SHOWER/THUNDERSTORM CHANCES LOOK TO CONTINUE THROUGH THE REST OF THE
PERIOD AS SOUTHWEST FLOW ALOFT BRINGS SEVERAL MID-LEVEL SHORTWAVE
ACROSS THE AREA ALONG WITH A LINGERING SURFACE FRONTAL BOUNDARY IN
THE VICINITY.
TEMPERATURE-WISE...ABOVE NORMAL TEMPERATURES LOOK TO CONTINUE
THROUGH SATURDAY. WILL HAVE TO WATCH SATURDAY AS THE MODELS DEPICT
MORE OF AN EASTERLY FLOW WITH STRATUS. THIS MAY KEEP TEMPERATURES
DOWN MORE THAN EXPECTED.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
340 PM CDT WED MAY 2 2012
02.12Z GFS AND ECMWF IN GOOD AGREEMENT IN BRINGING A LOW PRESSURE
SYSTEM FROM SOUTHERN CANADA AND THE PLAINS...EASTWARD INTO THE AREA
SUNDAY THROUGH SUNDAY NIGHT FOR THE LIKELIHOOD OF SHOWERS AND
THUNDERSTORMS. PATTERN SHIFT THEN OCCURS BEHIND THIS SYSTEM WITH
COOLER CYCLONIC FLOW DOMINATING THROUGH WEDNESDAY. STEEP LAPSE
RATES...ESPECIALLY DURING THE AFTERNOON HOURS UNDER THIS COOLER
CYCLONIC FLOW ALOFT IS EXPECTED TO LEAD TO SCATTERED
SHOWER/THUNDERSTORM ACTIVITY. OTHERWISE...LOOK FOR HIGH TEMPERATURES
THROUGH THE PERIOD IN THE UPPER 50S TO THE MIDDLE 60S.
&&
.AVIATION...THROUGH 06Z FRIDAY
1212 AM CDT THU MAY 3 2012
RATHER COMPLICATED FORECAST FOR THIS TAF CYCLE WITH LOW
CONFIDENCE. MAIN PRECIPITATION AREA HAS MOVED EAST OF THE TAF
SITES...BUT STILL WARM ADVECTION OVER THE REGION KEEPING SCATTERED
SHOWERS/TSRA AROUND THE AREA THROUGH THE OVERNIGHT HOURS.
SHORTWAVE OVER EASTERN NEBRASKA TO TRANSLATE NORTHEAST OVERNIGHT.
03.00Z HRRR SHOWS CONVECTION WITH THIS WAVE TO LIFT ACROSS IOWA
OVERNIGHT ARRIVING IN THE TAF SITES AROUND DAYBREAK OR A LITTLE
AFTER. IN BETWEEN THIS...CEILINGS WILL LIKELY BE IN THE MVFR/IFR
CATEGORY OVERNIGHT WITH JUST SOME SCATTERED CONVECTION AROUND THE
AREA. DID RAISE CEILINGS LATER THURSDAY AS WAVE MOVES EAST OF THE
AREA. STILL SOME UNCERTAINTY WITH ADDITIONAL CONVECTIVE DEVELOPMENT
IN THE AFTERNOON. FOR NOW LEFT IT OUT AND WILL HAVE TO BE RE-
EVALUATED WITH LATER MODEL RUNS. VFR CONDITIONS THEN EXPECTED
AFTER 00Z.
&&
.HYDROLOGY...TONIGHT
340 PM CDT WED MAY 2 2012
RAINFALL FROM LAST NIGHT THROUGH EARLY THIS
MORNING RANGED FROM 0.25 TO 1.50 INCHES. RIVERS SEEMED TO HAVE
HANDLED THIS FAIRLY WELL WITH ONLY SOME WITHIN BANK RISES.
HOWEVER...WITH ANOTHER 1.25-2.00 INCHES POSSIBLE TONIGHT...MAINLY
ALONG/SOUTH OF THE I-94 CORRIDOR...WILL HAVE TO KEEP A CLOSE EYE ON
AREA STREAMS AND RIVERS FOR SOME LOCALIZED FLOODING POTENTIAL.
HYDROLOGIC STATEMENTS HAVE ALREADY BEEN ISSUED FOR SEVERAL RIVERS
FOR THE RISES THAT EITHER HAVE OCCURRED OR ARE EXPECTED TO OCCUR.
PLEASE REFERENCE THE LATEST STATEMENTS /MKERVSARX FGUS83/ FOR THE
MOST CURRENT INFORMATION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
340 PM CDT WED MAY 2 2012
WI...NONE.
MN...NONE.
IA...FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR IAZ018-019-029-
030.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...RABERDING
HYDROLOGY...WELVAERT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1121 PM CDT WED MAY 2 2012
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...MADE SOME MINOR ADJUSTMENTS TO PCPN TRENDS AND ADDED A
MENTION OF HEAVY RAINFALL TO PARTS OF C/NE/EC WI OVERNIGHT.
A SMALL CLUSTER OF SVR TSTMS WITH LARGE HAIL HAVE PERSISTED FOR
SEVERAL HOURS OVER SOUTHERN MN...AND ARE NOW MOVG EAST INTO WC WI.
THESE ARE DEVELOPING JUST NORTH OF A WARM FRONT...WHICH EXTENDS
EASTWARD INTO CENTRAL WI. SHOWERS ARE INCREASING RAPIDLY OVER
SOUTHERN WI AND HEADING TOWARD C/EC WI...IN RESPONSE TO MOISTURE
CONVERGENCE AND INCREASING MUCAPE ON THE NOSE OF 30-40 KT LLJ.
OTHER CONVECTION WAS OCCURRING OVER THE EASTERN DAKOTAS...IN
RESPONSE TO A S/W TROF AND THE RRQ OF A STG UPPER LEVEL JET.
THE BIG QUESTION IS HOW ALL OF THIS WILL COME TOGETHER OVERNIGHT.
THE 23Z HRRR SEEMED TO HAVE A PRETTY GOOD HANDLE ON ALL THREE OF
THESE AREAS OF PCPN. THE HRRR GENERALLY WEAKENS THE CURRENT
CLUSTER OF STORMS IN WC WI AS IT MOVES TOWARD C WI. THIS MAY
HAPPEN AS THE DEVELOPING CONVECTION IN SOUTHERN WI TAKES OFF AND
CUTS OFF THE MOISTURE INFLOW. EVEN SO...THERE COULD BE A BRIEF
WINDOW OF OPPORTUNITY FOR LARGE HAIL IN C WI BETWEEN 04Z-06Z.
MODELS GENERALLY AGREE THAT A LARGE AREA OF SHOWERS AND TSTMS
WILL DEVELOP OVER C/EC/FAR NE WI DURING THE OVERNIGHT PERIOD...
WITH A THREAT OF HEAVY RAINFALL AS H8 DEW POINTS INCREASE TO
+10 TO +12 C AND PW SURGES TO NEAR 1.5 INCHES. THE CONVECTION
OVER THE NORTHERN PLAINS MAY BRUSH OUR FAR NORTHWEST COUNTIES
LATE TONIGHT.
KIECKBUSCH
&&
.PREV DISCUSSION...ISSUED AT 655 PM CDT WED MAY 2 2012...
SHORT TERM...TONIGHT AND THURSDAY.
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LOW
PRESSURE SITUATED OVER WESTERN KANSAS EARLY THIS AFTERNOON...AND A
COLD FRONT EXTENDING NORTHEAST INTO THE NORTHERN MISSISSIPPI
VALLEY. AN OUTFLOW BOUNDARY FROM THIS MORNINGS CONVECTION HAS
REACHED INTO NORTHERN MISSOURI AND CENTRAL ILLINOIS...THOUGH
CONVECTION HAS YET TO RE-DEVELOP. CLOUD COVER HAS BEEN BUILDING
ACROSS IOWA THIS AFTERNOON WHERE THETAE ADVECTION IS ONGOING...BUT
NO SIGN OF PRECIP HERE EITHER. MEANWHILE...MIXING INTO DRY AIR
ALOFT HAS DISSIPATED THIS MORNINGS CLOUD COVER INTO SCATTERED CU
OVER MUCH OF THE FORECAST AREA. AS A LOW LEVEL JET DEVELOPS AHEAD
THE LOW PRESSURE AND CONVECTION DEVELOPS UPSTREAM...SEVERE WEATHER
CHANCES AND PRECIP AMOUNTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...PLENTY OF UNCERTAINTY WITH THE DETAILS CONCERNING
POTENTIAL CONVECTION. SHORTWAVE TROUGH OVER MONTANA WILL LIFT NE
OVER NORTH DAKOTA AND INTO SOUTH-CENTRAL CANADA. SW FLOW ALOFT WILL
KEEP LOW PRESSURE OVER THE CENTRAL PLAINS WHILE THE COLD FRONT BECOMES
MORE PERPENDICULAR TO THE LOW LEVEL FLOW OVER IOWA AND INTO
WISCONSIN. AHEAD OF THE SURFACE LOW...A SOUTH TO SOUTHWEST LLJ WILL
DEVELOP LATE THIS AFTERNOON INTO THIS EVENING POINTING INTO IOWA AND
NORTHERN ILLINOIS. GOOD MASS CONVERGENCE ON THE NOSE OF THIS LLJ IN
AN AREA OF MU CAPE 1500-2000 J/KG AND MID-LEVEL LAPSE RATES OF 7 TO
7.5 C/KM SHOULD BE SUFFICIENT TO TRIGGER ELEVATED CONVECTION.
FORWARD PROPAGATING CORFIDI VECTORS WOULD TRACK SUBSEQUENT MCS
ENE...THOUGH AM EXPECTING THE STRONGEST THUNDERSTORMS TO FOLLOW THE
GREATEST INSTABILITY OVER THE SOUTHERN 1/3RD OF THE BADGER STATE AND
NORTHERN ILLINOIS. THE 12Z GFS DOES TRY TO RAM THE LLJ INTO EAST-CENTRAL
WISCONSIN ALONG WITH AMPLE INSTABILITY...BUT THINK THIS IS TOO
AMBITIOUS GIVEN THE WSW FLOW ALOFT AND WITHOUT MUCH MID-LEVEL HEIGHT
RISES. THE FLOW DOES TURN A BIT MORE SW OVERNIGHT AS THE RIGHT REAR
QUAD OF A JET STREAK SHIFTS INTO NORTHERN WISCONSIN...SO AM
EXPECTING TO SEE A MORE NORTHWARD PUSH OF THE NOCTURNAL CONVECTION
ACROSS THE FORECAST AREA AFTER MIDNIGHT. WITH THE ELEVATED
INSTABILITY AXIS REMAINING TO OUR SOUTH...HAVE A HARD TIME GETTING
EXCITED ABOUT SEVERE CHANCES...THOUGH ALWAYS TOUGH TO RULE OUT A
MARGINAL SEVERE STORM ADVECTING INTO THE SOUTHERN FORECAST AREA.
WILL KEEP A MENTION OF SEVERE POSSIBILITIES FOR CENTRAL AND
EAST-CENTRAL WISCONSIN...MAINLY FOR LARGE HAIL...AND STRONG WINDS TO
A LESSER EXTENT. CENTRAL AND EAST-CENTRAL WISCONSIN WILL LIKELY SEE
SUBSTANTIAL RAINFALL...WITH SOME GUIDANCE POINTING TOWARDS WELL OVER
AN INCH OF RAIN. WILL TRY TO CAP IT AROUND THERE...SINCE THE
GREATER INSTABILITY IS SOUTH OF THE FORECAST AREA.
THURSDAY...MORNING CONVECTION MAY VERY WELL BE ONGOING AT THE START
OF THE PERIOD...AS THE RIGHT REAR QUAD OF THE JET STREAK WILL BE
OVERHEAD WHILE 850MB CONVERGENCE WILL BE DRAPED OVER CENTRAL
WISCONSIN. THINK THE MORNING MAY TURN OUT TO BE WETTER THAN MODELS
INDICATE AND WILL KEEP THE NEAR CATEGORICAL POPS IN THE FORECAST.
INSTABILITY WILL BE THE QUESTION MARK FOR THE AFTERNOON...AS THE
WARM FRONT WILL REMAIN STALLED ACROSS THE AREA. THE RIGHT REAR QUAD
OF THE JET STREAK WILL PULL OUT BY THE AFTERNOON...BUT WILL DAYTIME
HEATING LEAD TO CLEARING...DESPITE AMPLE MOISTURE THROUGH THE
COLUMN? THINK ANY BREAKS WILL JUST LEAD TO CU BUILD-UP...RESULTING
IN A MOSTLY CLOUDY DAY REGARDLESS. STILL SOME CAPE TO BE HAD...SO
CANNOT RULE OUT SCATTERED COVERAGE OF SHOWERS AND STORMS THROUGH THE
AFTERNOON. WILL MAKE ONLY COSMETIC CHANGES TO POPS. HIGHS IN THE
LOW TO MID 70S.
LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY. PCPN CHANCES
WILL BE THE PRIMARY FORECAST ISSUE DURING THIS PERIOD. BUSY WSW
FLOW TO CONTINUE INTO FRIDAY BEFORE MEDIUM RANGE MODELS IN
AGREEMENT WITH BRIEFLY BUILDING AN UPPER RIDGE OVER THE WESTERN
GREAT LAKES REGION SATURDAY INTO SUNDAY. THIS UPPER RIDGE BEGINS
TO FLATTEN LATE IN THE WEEKEND WITH A RETURN TO A SOUTH TO
SOUTHWEST FLOW AHEAD OF A SHORT WAVE TROUGH. MEANWHILE THE
SURFACE BOUNDARY WITH BEST INSTABILITY DROPS WELL SOUTH OF THE
FORECAST AREA LATER FRIDAY INTO FRIDAY NIGHT WITH AN EAST TO
NORTHEAST FLOW AROUND A SURFACE HIGH OVER SOUTHERN CANADA.
WOULD NORMALLY BE AGGRESSIVE WITH ENDING POPS IN THIS
SCENARIO...BUT MDM RANGE MODELS ARE CONSISTENTLY LINGERING A WEAK
H8 BOUNDARY OVER WISCONSIN FOR A POSSIBLE FOCUS OF CONVECTION FOR
AT LEAST A CHANCE OF SHOWERS. THIS H8 BOUNDARY WITH WARMER H8 TEMPS WERE
PRODUCING TOTAL TOTAL VALUES IN THE LOWER 50S...ESPECIALLY TOWARD
WESTERN WISCONSIN. IN ADDITION...BEST UPPER JET DYNAMICS LINGER
ACROSS THE NORTHERN GREAT LAKES REGION TO PROVIDE AREAS OF LIFT.
FOR THE NEW WORK WEEK...A PROGGED DEEPENING UPPER TROUGH WITH
FRONTAL SYSTEM WILL PROVIDE MORE EVEN PCPN CHANCES OF PCPN
THROUGH AT LEAST WEDNESDAY BEFORE A HIGH PRESSURE RIDGE TRIES TO
BUILD IN FROM THE NORTHERN PLAINS AND CANADA. BY MID WEEK NEXT
WEEK PCPN CHANCES MAY BE PRIMARILY DIURNAL VARIETY AS THE UPPER
TROUGH SLOWLY DRIFTS OVER.
HYDROLOGY...RAINFALL AMOUNTS OVER CENTRAL AND EAST CENTRAL
WISCOMSIN FROM LAST NIGHS CONVECTION RANGED FROM 0.40 TO 0.80
INCHES. MORE RAIN IS ANTICIPATED TONIGHT INTO THRUSDAY MORNING AS
A WARM FRONT LIFTS INTO SOUTHERN AND CENTRAL WISCONSIN. PWATS
APPROACH 1.50 BY THURSDAY MORNING. AT THIS TIME BETWEEN 1 TO 1.50
INCHES AREAS RAIN IS EXPECTED FROM TONIGHT THROUGH NOON THURSDAY.
DO NOT EXPECT FLOODING AT THESE NUMBERS...BUT IF STORMS BECOME
MORE WIDESPREAD AND CAN TRAIN ALONG THE WARM FRONT...LOCALLY
HIGHER AMOUNTS POSSIBLE. MAIN STEM RIVERS ARE FAIRLY LOW SO
RUNOFF IS NOT EXPECTED TO IMPACT RIVERS...HOWEVER SMALL STREAMS
MAY BEGIN TO BECOME SWOLLEN IF THE HIGHER AMOUNTS VERIFY.
&&
.AVIATION...SHOWERS AND TSTMS WERE DEVELOPING OVER C/EC WI LATE
THIS EVG...AND SHOULD BRING SMALL HAIL...HEAVY RAINFALL AND
MVFR/IFR CONDITIONS TO AREAS SE OF A LINE FROM AUW TO MNM OVERNIGHT.
ADDITIONAL SHOWERS AND STORMS APPROACHING FROM THE NORTHERN PLAINS
AND NORTHERN MN MAY BRUSH THROUGH NC WI LATE TONIGHT INTO EARLY
THURSDAY. THE SHOWERS AND TSTMS ARE EXPECTED TO TAPER OFF BY
THURSDAY MORNING...WITH A MIX OF VFR AND MVFR CONDITIONS EXPECTED
DURING THE DAY. SCT TSTMS MAY REDEVELOP AS A COLD FRONT SAGS SE
ACROSS THE FORECAST AREA THURSDAY AFTERNOON AND EARLY EVG.
KIECKBUSCH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NEW YORK NY
755 AM EDT THU MAY 3 2012
.SYNOPSIS...
A WARM FRONT OVER THE MID-ATLANTIC WILL SLOWLY TRACK TOWARDS THE
REGION TODAY...DRAWING CLOSE TONIGHT...AND PASSING THROUGH
PORTIONS OF THE TRI-STATE REGION ON FRIDAY. LOW ASSOCIATED WITH
WARM FRONT MOVES SOUTH OF LONG ISLAND BY SATURDAY MORNING. THE
LOW SLOWLY MOVES FARTHER OUT TO SEA WITH HIGH PRESSURE STAYING IN
ONTARIO AND QUEBEC ON SATURDAY. BY SUNDAY...THIS HIGH PRESSURE
AREA WILL START TO BUILD INTO THE NORTHEAST AND OVER THE LOCAL
REGION ON MONDAY. HIGH PRESSURE SHIFTS OFFSHORE MONDAY NIGHT WITH
ANOTHER AREA OF LOW PRESSURE SLOWLY MOVING NEAR THROUGH MIDDLE OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE ANCHORED WELL TO THE NORTH AND EAST WITH THE REGION
ON THE SOUTHWEST PERIPHERY OF IT...YIELDING A LIGHT SOUTHEAST FLOW
ACROSS THE REGION. SHOWERS HAVE ENDED ACROSS THE REGION BUT KEPT
A MENTION OF ISOLATED SHOWERS FOR THIS MORNING THAT COULD DEVELOP
ACROSS THE REGION WITH MOST MODEL QPF SHOWING A FEW HUNDREDTHS OF
AN INCH. HRRR MODEL ALSO SHOWS A FEW SHOWERS ACROSS THE AREA EARLY
THIS MORNING ACCORDING TO ITS REFLECTIVITY FIELDS. THERE WILL BE A
LITTLE FORCING MOSTLY AT LOW LEVELS WITH DPVA AND WEAK SFC
CONVERGENCE WITH THIS MOIST SE FLOW. IN ADDITION...PATCHY FOG WAS
ADDED FOR NEXT FEW HOURS MAINLY ACROSS SOME INLAND AREAS WITH THE
PREVIOUS RAIN ADDING TO THE MOISTURE AND SATURATION AT THE SFC.
FOG SHOULD DISSIPATE BY LATE MORNING AND MOST SHOWERS WILL HAVE
BEEN FINISHED AS WELL BY THAT POINT WITH DYNAMICS LESS FAVORABLE
GOING INTO THE AFTERNOON. OTHERWISE CLOUDS...TEMPS...DEWPOINTS...AND
WINDS ON TRACK.
WARM FRONT WILL REMAIN S OF THE CWA TODAY. THIS WILL ALLOW FOR A
GENERAL E TO ESE FLOW. DESPITE ALL THE DRY AIR AT 6K FT AND
ABV...THE MOIST MARITIME FLOW AT THE LLVLS WILL KEEP THE LOW
CLOUDS LOCKED IN THRU THE DAY. TEMPS A BLEND OF GUIDANCE...WARMEST
ACROSS THE W WHERE IT MAY GO PTCLDY FOR A TIME THIS AFTN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
LIKELY TO BE ANOTHER MCS IN THE NERN CONUS TNGT. THE CWA WILL BE
IN THE PRIME REGION OF THE MID LVL INSTABILITY AXIS AS IT BUILDS
NWD. HIGH CHANCE POPS. CONVECTION ALONG THE RING OF FIRE IS
PROGGED TO LAST INTO FRI ALONG THE NERN 1/3 OF THE CWA. SECOND
AREA OF CONVECTION...THIS TIME SURFACE BASED...SHOULD DEVELOP
ACROSS WRN PORTIONS OF THE CWA DURING THE AFTN. THE 00Z NAM
INDICATES A PRIME BRN IN THE 15-35 RANGE FOR SUPERCELL POTENTIAL.
IF THIS PANS OUT...SOME SVR CELLS ALONG AND MAINLY WEST OF THE
HUDSON AFT 18Z. AS CONVECTION TRACKS SEWD IN THE LATE AFTN AND
EVE...THE TSTMS SHOULD TRANSITION TO ELEVATED WITH SOME SMALL HAIL
AND HVY RAIN ACROSS THE REST OF THE CWA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
STARTING OUT THE LONG TERM ON FRIDAY NIGHT...WEATHER WILL STILL BE
UNSETTLED. 500MB PATTERN SHOWS A WNW FLOW ALOFT AS THE REGION WILL
BE EASTERN SIDE OF A RATHER FLAT LONGWAVE RIDGE SETTING UP ACROSS
THE NATION. SMALL IMPULSE SHOWN BY PVA WILL BE MOVING THROUGH ON THE
TOP OF THE RIDGE EARLY IN THE NIGHT WITH SOME NVA TOWARDS SAT
MORNING. THE DYNAMIC FORCING FOR LIFTING WILL BE ON A DECLINE
THROUGH THE NIGHT AS SHOWN BY UNFAVORABLE POSITION OF THE REGION
WITH RESPECT TO THE JET AS THE REGION WILL BE IN THE RIGHT FRONT
QUADRANT ALONG WITH Q VECTOR DIVERGENCE FROM 850 TO 500 MB. AT THE
SURFACE...LOW ASSOCIATED WITH WARM FRONT MOVES SOUTH OF LONG ISLAND
BY SATURDAY MORNING. WITH MUCAPE STILL PRESENT WITH VALUES UP TO
ALMOST 200 J/KG FOR SOUTHERN PORTIONS OF THE FORECAST
REGION...THUNDERSTORMS WILL BE POSSIBLE ALONG WITH SHOWERS. THE
THUNDER POTENTIAL DIMINISHES LATE ALONG WITH SHOWER PROBABILITIES
OVERALL WITH LESS DYNAMICAL FORCING. WITH MOISTURE IN THE BOUNDARY
LAYER AND WINDS BECOMING LIGHT...SOME PATCHY FOG WAS INSERTED INTO
THE FORECAST FOR THE OVERNIGHT PERIOD GOING INTO EARLY SATURDAY
MORNING. LOWS A BLEND OF MAV AND MET BUT WEIGHED MORE TO THE WARMER
MAV NUMBERS.
FOR THE WEEKEND...FLOW ALOFT BECOMES MORE NW...WNW SATURDAY AND NW
SUNDAY. ANOTHER IMPULSE OF PVA AT 500MB APPROACHING SATURDAY
AFTERNOON AND IS FORECAST TO MOVE THROUGH SATURDAY NIGHT. THIS IS A
RESPONSE TO AN UPPER LEVEL LOW IN QUEBEC THAT IS SHOWN TO STRETCH
AND MOVE SOUTHEAST OVER THE COURSE OF THE WEEKEND. THE JET SHARPENS
AND INCREASES JUST NORTH OF THE GREAT LAKES AND GOES INTO NORTHERN
NEW ENGLAND. AT THE SURFACE...REGION STAYS IN A NE FLOW WITH THE
WEAK LOW MOVING SLOWLY FURTHER AWAY OFFSHORE AND A STRONG HIGH
PRESSURE AREA STAYING WITHIN SOUTHEAST CANADA. THIS STARTS TO BUILD
A LITTLE FARTHER SOUTHEAST ON SUNDAY. TOOK AN ENSEMBLE APPROACH TO
THE PRECIP FORECAST...AND WITH GFS ENSEMBLE AND SREF HAVING
SIGNIFICANTLY LOWER CHANCES FOR MEASURABLE RAIN. THEREFORE JUST
HAVE A SLIGHT CHANCE FOR SHOWERS TO REFLECT THIS. MAX TEMPS A BLEND
OF MAV AND MET AS WELL AS NAM12 TO CONVEY LOWER TEMPS. TEMPERATURES
ARE STILL MILD OVERALL THOUGH WITH MAX TEMPS IN THE WESTERN AREAS
CLOSE TO 70 AND PROGRESSIVELY COOLER TO THE EAST WITH MORE MARITIME
INFLUENCE WITH HIGHS THERE NOT GETTING MUCH BEYOND UPPER 50S TO
LOWER 60S.
MORE STABILIZING EFFECT FROM RIDGE TOWARDS LATE SUNDAY NIGHT INTO
MONDAY. HIGH PRESSURE BUILDS AT THE SURFACE MORE INTO THE REGION AND
MORE OF SUBSIDENCE EFFECT OVERALL WILL RESULT IN DRIER CONDITIONS
SATURDAY NIGHT AND DECREASING CLOUDS ON SUNDAY. A MORE WIDESPREAD
MILD DAY IS IN STORE WITH MID TO UPPER 60S FOR MAX TEMPS. SOME
COOLER AIR DOES ADVECT IN ON A MORE NORTHERLY FLOW SATURDAY NIGHT
THROUGH EARLY SUNDAY.
ANOTHER IMPULSE APPROACHES MONDAY NIGHT AND MOVES THROUGH ON
TUESDAY. 250MB RIDGE AXIS MOVES ACROSS BEGINNING OF NEXT WEEK...WITH
DECREASING WINDS...SLOWING DOWN THE SYNOPTIC FLOW. FLOW ALOFT
BECOMES FLAT TO PARTIALLY MERIDIONAL. HIGH PRESSURE SFC DOMINANT
FEATURE FOR MONDAY AS IT BUILDS MORE INTO THE REGION BUT QUICKLY
MOVES OFFSHORE MONDAY NIGHT AND INTO TUESDAY. NEXT FRONTAL SYSTEM
SLOWLY APPROACHES FROM THE WEST MONDAY NIGHT AND INTO THE AREA ON
TUESDAY. WEAK LOW CENTER MOVES JUST SOUTH OF THE REGION BY MIDWEEK.
CHANCES FOR SHOWERS WILL INCREASE TOWARDS MIDWEEK. TIMING
DIFFERENCES OF THESE SFC FEATURES DUE TO UPPER LEVEL FLOW
DIFFERENCES PARTICULARLY BETWEEN THE GFS AND ECMWF. TEMPERATURES A
BLEND OF HPC AND MOSGUIDE. OVERALL...FORECAST TEMPS ARE NEAR TO
SLIGHTLY ABOVE NORMAL FOR EARLY TO MID NEXT WEEK.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
IFR CONDITIONS AT MOST TERMINALS SHOULD LAST INTO AT LEAST MID
MORNING. DAYTIME HEATING SHOULD GRADUALLY LIFT CIGS TO MVFR BY
LATE MORNING OR EARLY AFTERNOON...THEN CIGS LOWER AGAIN TO IFR AT
NIGHT. ANOTHER ROUND OF SHOWERS/TSTMS POSSIBLE TOWARD THE END OF
THE 06Z TAF PERIOD.
SE-S FLOW UNDER 10 KT EARLY WILL BECOME MORE S THIS MORNING...
THEN BACK SE AGAIN SE AGAIN BY LATE AFTERNOON AND REMAIN SE TONIGHT.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: TIMING OF IMPROVEMENT TO MVFR UNCERTAIN.
KLGA FCSTER COMMENTS: TIMING OF IMPROVEMENT TO MVFR UNCERTAIN.
KEWR FCSTER COMMENTS: TIMING OF IMPROVEMENT TO MVFR UNCERTAIN.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KHPN FCSTER COMMENTS: TIMING OF IMPROVEMENT TO MVFR UNCERTAIN.
KISP FCSTER COMMENTS: TIMING OF IMPROVEMENT TO MVFR UNCERTAIN.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.FRI...GENERALLY MVFR OR LOWER. AREAS ALONG/WEST OF THE HUDSON
COULD BREAK OUT TO VFR IN THE AFTN. CHANCE OF SHOWERS IN THE
MORNING...THEN A CHANCE OF TSTMS WITH HEAVY RAIN/GUSTY WINDS IN
THE AFTERNOON.
.SAT-MON...MAINLY VFR. SCT SHOWERS ON SAT.
&&
.MARINE...
A WARM FRONT WILL REMAIN S OF THE WATERS TODAY. LIGHT ESE FLOW CAN
BE EXPECTED. THE FRONT WILL APPROACH THE WATERS TNGT...THE PASS
THE WRN WATERS ON FRI. WINDS AND SEAS WILL BE BLW SCA LVLS THRU
THE PERIOD. THERE WILL BE A CHANCE OF TSTMS TNGT...THEN AGAIN ON
FRI.
SUB SCA CONDITIONS ARE EXPECTED THROUGH THE LONG TERM WITH PRESSURE
GRADIENTS WEAK ENOUGH TO KEEP WIND GUSTS BELOW 25 KT AND SEAS BELOW
5 FT. THE ONLY CHANCE FOR SCA CONDITIONS WOULD BE ON SATURDAY AND SATURDAY
NIGHT ACROSS THE OUTER OCEAN WHERE THE OFFSHORE LOW AND ITS
ASSOCIATED SWELL THAT MAY PUSH SEAS TO 5 FT.
&&
.HYDROLOGY...
LOCALLY HVY RAINFALL WILL BE POSSIBLE IN TSTMS ON FRI. MINOR URBAN
AND POOR DRAINAGE FLOODING WILL BE POSSIBLE WHERE THE MOST INTENSE
ACTIVITY OCCURS. BASIN AVERAGE QPF THRU FRI WILL BE 1/4 TO 3/4 OF
AN INCH ACROSS THE ENTIRE AREA.
UP TO ANOTHER QUARTER INCH OF RAIN FORECAST FOR FRI NIGHT WITH
SHOWERS AND THUNDERSTORMS...MAINLY IN THE EVENING. SOME LOCALLY
HIGHER AMOUNTS POSSIBLE. SOME MEASURABLE RAIN ALSO POSSIBLE
SATURDAY. OTHERWISE...NO SIGNIFICANT RAINFALL EXPECTED THROUGH
MONDAY.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JM/12
NEAR TERM...JM/12
SHORT TERM...12
LONG TERM...JM
AVIATION...GOODMAN
MARINE...JM/12
HYDROLOGY...JM/12
AREA FORECAST DISCUSSION
NWS LINCOLN IL
946 AM CDT THU MAY 3 2012
.DISCUSSION...
ISSUED 946 AM CDT THU MAY 3 2012
A BREEZY AND VERY WARM DAY IS UNFOLDING ACROSS CENTRAL ILLINOIS
TODAY. CONVECTIVE COMPLEX OVER NORTHWEST MISSOURI WILL CONTINUE TO
DISSIPATE AS IT TRACKS EASTWARD...WITH LITTLE OR NO PRECIP FROM
THIS SYSTEM EXPECTED TO CROSS THE MISSISSIPPI RIVER. MAIN QUESTION
WILL BE WHETHER OR NOT ANY STORMS CAN FIRE ALONG MESOSCALE BOUNDARIES
ACROSS THE AREA THIS AFTERNOON. FORECAST SOUNDINGS INDICATE A
MODERATELY UNSTABLE ENVIRONMENT WITH LITTLE OR NO CAPPING...SO
ONLY MISSING INGREDIENT WOULD BE A GOOD FOCUSING MECHANISM. IT
APPEARS THE PRIMARY OUTFLOW BOUNDARY FROM THE MISSOURI COMPLEX IS
DROPPING S/SE INTO CENTRAL MISSOURI...HOWEVER OTHER SMALLER SCALE
BOUNDARIES COULD BE PRESENT FURTHER EAST INTO ILLINOIS. AT THIS
TIME...WILL CONFINE AFTERNOON STORM CHANCES TO THE ILLINOIS RIVER
VALLEY WESTWARD. DUE TO MOIST AIRMASS AND STEEP LAPSE RATES...SCT-BKN
CU WILL LIKELY DEVELOP TODAY. CU-RULE SUPPORTS THIS...SO HAVE
UPDATED SKY GRIDS TO GO WITH PARTLY SUNNY WORDING ACROSS MUCH OF
THE AREA. WITH A GOOD DEAL OF SUNSHINE AND STRONG SOUTHERLY WINDS
EXPECTED...AFTERNOON HIGH TEMPS WILL REACH THE MIDDLE TO UPPER 80S
ACROSS THE BOARD.
BARNES
&&
.AVIATION...
ISSUED 631 AM CDT THU MAY 3 2012
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES NEXT 24RHS. HIGH
CIRRUS WILL OVERSPREAD THE AREA AND ALL SITES THIS MORNING.
HOWEVER...SOME SCATTERED CU SHOULD DEVELOP OVER THE AREA AS WELL
AND AFFECT THE TAFS STARTING AROUND 15Z. THESE CONDITIONS WILL
CONTINUE THROUGH THIS AFTERNOON AND INTO EARLY EVENING. A LARGE
AREA OF THUNDERSTORMS IN NORTHEAST MO WILL MOVE EAST ACROSS
NORTHERN MO AND PUSH INTO WEST CENTRAL IL TONIGHT. ADDITIONAL
THUNDERSTORMS SHOULD DEVELOP ON OUTFLOWS OF THE EXISTING SYSTEM
AND SHOULD AFFECT PIA AROUND 01Z AND 02Z AT BMI. STORMS COULD TAKE
A TURN TO THE SOUTH TONIGHT SO THUNDERSTORMS SHOULD GET INTO
SPI/DEC/CMI AROUND 04Z. SHORT TERM MODELS STILL DO NOT SEEM TO
HAVE GOOD HANDLE ON CURRENT TRENDS. SO WILL JUST HAVE VCTS IN
FORECAST FOR TONIGHT AND LET LATER SHIFTS DECIDE ON TIMING OF
TEMPO GROUPS. WINDS WILL BECOME A LITTLE BIT SOUTHWESTERLY AND
INCREASE IN SPEED TODAY...THEN TAPER OFF AGAIN DURING THE EVENING.
AUTEN
&&
.PREV DISCUSSION...
ISSUED 320 AM CDT THU MAY 3 2012
WEAK RIDGING OVER THE EASTERN HALF OF THE CONUS THIS
MORNING...AND SOUTHWESTERLY FLOW OVER MUCH OF THE SOUTHERN PLAINS
AND INTO THE MIDWEST KEEPING A STRING OF CONVECTIVE WAVES MOVING
INTO THE REGION. THIS MORNING...ANOTHER WAVE OVER THE CENTRAL
MISSOURI RIVER VALLEY AND WRN IA EXPECTED TO MOVE INTO THE UPPER
MIDWEST LATER TODAY. FIRST ISSUE FOR THE FORECAST IS THE TIMING OF
THE WAVE...AND THE PRECIP INTO THE CURRENT AIRMASS FOR CENTRAL
ILLINOIS...WHICH BY THE 00Z SOUNDING IS RELATIVELY DRY. MODELS
HAVING A BIT OF AN ISSUE WORKING OUT THE CURRENT CONVECTION...MUCH
LESS ITS PROGRESSION. BOUNDARY SINKING THROUGH TONIGHT AND
INCREASING THE POPS THROUGH TONIGHT AND INTO TOMORROW MORNING.
SHOWERS AND TS CONTINUE THROUGH THE FIRST PORTION OF THE WEEKEND.
CONCERNS STILL FOR WHERE THE BREAKS IN THE PRECIP MAY BE...BEFORE
THE LARGER SCALE TROF OVER THE NWRN CONUS BEGINS TO MOVE OUT...AND
THE SFC LOW DRAGS THROUGH THE MIDWEST MON/MON NIGHT...LEAVING A
BRIEF RESPITE FROM THE RAINFALL IN THE MIDDLE OF THE NEXT WORK
WEEK.
SHORT TERM...TODAY AND TOMORROW...
WARM AND MUGGY CONDITIONS AS SOUTHERLY WINDS USHER WARM AIR INTO
THE MIDWEST. A BIT OF A QUESTION MARK REMAINS THE HIGH TEMPS NW OF
THE ILLINOIS RIVER VALLEY...WHERE CLOUD COVER IS ENHANCED BY DYING
MCS PASSING TO THE NW THIS MORNING. CLOUD COVER/COLD POOL LIKELY TO
INHIBIT THE WARM UP A BIT...THOUGH THE SOUTHERLY WINDS ARE
COUNTERING. MUCH SUNNIER TO THE SOUTH AND EAST OF THE INTERSTATE
55 CORRIDOR...AND TEMPS SOARING INTO THE MID TO UPPER 80S...850MB
TEMPS IN THE 17-18C RANGE...AND MIXING DOWN SOME 20-25MPH GUSTS.
ISSUE FOR THE CURRENT POPS...WHICH THE HRRR IS THE ONLY MODEL TO
REALLY DEPICT WELL...ALBEIT ABOUT 2 HOURS BEHIND AND A LITTLE
UNDERDONE...IS THE ARRIVAL AND POTENTIAL IMPACT TO AREAS IN THE
NRN TIER OF THE STATE AND CWA LATER THIS AFTERNOON. HAVE SLIGHTLY
ADJUSTED SOME HIGHER CHANCE POPS FOR THIS TREND AND MAY NEED TO
KEEP A CLOSE LOOK FOR THIS AFTERNOON IN MORE OF THE HIGH RES
SOLUTIONS. THIS EVENING AND TONIGHT...PRECIP CHANCES INCREASE AS
THE UPPER RIDGE STARTS TO BREAK DOWN AND THE CONVECTION TO THE NW
PUSHES INTO THE FA. MODELS CONTINUE TO PUSH SMALL REINFORCING
SHORTWAVES TO KEEP THE REGION IN PRECIP THROUGH MUCH OF FRIDAY OFF
AND ON.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
POSSIBLE BREAK FOR PART OF SATURDAY IN THE SHOWERY PRECIP...AT
LEAST BEING HINTED IN THE MODELS AS MORE DETAIL WORKS IN...WITH
THE LARGER SCALE SYSTEM PUSHING IN SAT NIGHT WITH THE UPPER LOW ON
THE MOVE ACROSS THE NRN PLAINS. STRONGER SFC LOW ACROSS THE NRN
BOUNDARY OF THE CONUS...DEEP TROF/FRONTAL BOUNDARY TO WEAKER
SOUTHERN SFC LOW PUSHING A BOUNDARY THROUGH THE MIDWEST SUN/MON
AND A RETURN OF THE POPS AGAIN THROUGH THE END OF THE
FORECAST...WITH BEST CHANCES SUN NIGHT THROUGH MON NIGHT FOR MORE
EXTENSIVE RAIN AS THE SFC LOW IS SLIGHTLY SLUGGISH TO MOVE OUT.
ECMWF IS A BIT SLOWER THAN THE GFS...BUT NOT TOO FAR OFF
ALTOGETHER. A SMALL BREAK IN THE HEAT WITH THE SYSTEM AS HIGHS FOR
MON/TUES A BIT LOWER WITH THE MID LEVEL TROF GETTING SOME COOLER
AIR OVHD BEHIND THE RIDGE. COOLER TEMPS CONTINUE THROUGH MIDWEEK
AS THE UPPER TROF SLOWS AS WELL...THOUGH SFC STARTS TO DRY OUT A
BIT WED NIGHT.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
631 AM CDT THU MAY 3 2012
.DISCUSSION...
ISSUED 320 AM CDT THU MAY 3 2012
WEAK RIDGING OVER THE EASTERN HALF OF THE CONUS THIS
MORNING...AND SOUTHWESTERLY FLOW OVER MUCH OF THE SOUTHERN PLAINS
AND INTO THE MIDWEST KEEPING A STRING OF CONVECTIVE WAVES MOVING
INTO THE REGION. THIS MORNING...ANOTHER WAVE OVER THE CENTRAL
MISSOURI RIVER VALLEY AND WRN IA EXPECTED TO MOVE INTO THE UPPER
MIDWEST LATER TODAY. FIRST ISSUE FOR THE FORECAST IS THE TIMING OF
THE WAVE...AND THE PRECIP INTO THE CURRENT AIRMASS FOR CENTRAL
ILLINOIS...WHICH BY THE 00Z SOUNDING IS RELATIVELY DRY. MODELS
HAVING A BIT OF AN ISSUE WORKING OUT THE CURRENT CONVECTION...MUCH
LESS ITS PROGRESSION. BOUNDARY SINKING THROUGH TONIGHT AND
INCREASING THE POPS THROUGH TONIGHT AND INTO TOMORROW MORNING.
SHOWERS AND TS CONTINUE THROUGH THE FIRST PORTION OF THE WEEKEND.
CONCERNS STILL FOR WHERE THE BREAKS IN THE PRECIP MAY BE...BEFORE
THE LARGER SCALE TROF OVER THE NWRN CONUS BEGINS TO MOVE OUT...AND
THE SFC LOW DRAGS THROUGH THE MIDWEST MON/MON NIGHT...LEAVING A
BRIEF RESPITE FROM THE RAINFALL IN THE MIDDLE OF THE NEXT WORK
WEEK.
SHORT TERM...TODAY AND TOMORROW...
WARM AND MUGGY CONDITIONS AS SOUTHERLY WINDS USHER WARM AIR INTO
THE MIDWEST. A BIT OF A QUESTION MARK REMAINS THE HIGH TEMPS NW OF
THE ILLINOIS RIVER VALLEY...WHERE CLOUD COVER IS ENHANCED BY DYING
MCS PASSING TO THE NW THIS MORNING. CLOUD COVER/COLD POOL LIKELY TO
INHIBIT THE WARM UP A BIT...THOUGH THE SOUTHERLY WINDS ARE
COUNTERING. MUCH SUNNIER TO THE SOUTH AND EAST OF THE INTERSTATE
55 CORRIDOR...AND TEMPS SOARING INTO THE MID TO UPPER 80S...850MB
TEMPS IN THE 17-18C RANGE...AND MIXING DOWN SOME 20-25MPH GUSTS.
ISSUE FOR THE CURRENT POPS...WHICH THE HRRR IS THE ONLY MODEL TO
REALLY DEPICT WELL...ALBEIT ABOUT 2 HOURS BEHIND AND A LITTLE
UNDERDONE...IS THE ARRIVAL AND POTENTIAL IMPACT TO AREAS IN THE
NRN TIER OF THE STATE AND CWA LATER THIS AFTERNOON. HAVE SLIGHTLY
ADJUSTED SOME HIGHER CHANCE POPS FOR THIS TREND AND MAY NEED TO
KEEP A CLOSE LOOK FOR THIS AFTERNOON IN MORE OF THE HIGH RES
SOLUTIONS. THIS EVENING AND TONIGHT...PRECIP CHANCES INCREASE AS
THE UPPER RIDGE STARTS TO BREAK DOWN AND THE CONVECTION TO THE NW
PUSHES INTO THE FA. MODELS CONTINUE TO PUSH SMALL REINFORCING
SHORTWAVES TO KEEP THE REGION IN PRECIP THROUGH MUCH OF FRIDAY OFF
AND ON.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
POSSIBLE BREAK FOR PART OF SATURDAY IN THE SHOWERY PRECIP...AT
LEAST BEING HINTED IN THE MODELS AS MORE DETAIL WORKS IN...WITH
THE LARGER SCALE SYSTEM PUSHING IN SAT NIGHT WITH THE UPPER LOW ON
THE MOVE ACROSS THE NRN PLAINS. STRONGER SFC LOW ACROSS THE NRN
BOUNDARY OF THE CONUS...DEEP TROF/FRONTAL BOUNDARY TO WEAKER
SOUTHERN SFC LOW PUSHING A BOUNDARY THROUGH THE MIDWEST SUN/MON
AND A RETURN OF THE POPS AGAIN THROUGH THE END OF THE
FORECAST...WITH BEST CHANCES SUN NIGHT THROUGH MON NIGHT FOR MORE
EXTENSIVE RAIN AS THE SFC LOW IS SLIGHTLY SLUGGISH TO MOVE OUT.
ECMWF IS A BIT SLOWER THAN THE GFS...BUT NOT TOO FAR OFF
ALTOGETHER. A SMALL BREAK IN THE HEAT WITH THE SYSTEM AS HIGHS FOR
MON/TUES A BIT LOWER WITH THE MID LEVEL TROF GETTING SOME COOLER
AIR OVHD BEHIND THE RIDGE. COOLER TEMPS CONTINUE THROUGH MIDWEEK
AS THE UPPER TROF SLOWS AS WELL...THOUGH SFC STARTS TO DRY OUT A
BIT WED NIGHT.
HJS
&&
.AVIATION...
ISSUED 631 AM CDT THU MAY 3 2012
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES NEXT 24RHS. HIGH
CIRRUS WILL OVERSPREAD THE AREA AND ALL SITES THIS MORNING.
HOWEVER...SOME SCATTERED CU SHOULD DEVELOP OVER THE AREA AS WELL
AND AFFECT THE TAFS STARTING AROUND 15Z. THESE CONDITIONS WILL
CONTINUE THROUGH THIS AFTERNOON AND INTO EARLY EVENING. A LARGE
AREA OF THUNDERSTORMS IN NORTHEAST MO WILL MOVE EAST ACROSS
NORTHERN MO AND PUSH INTO WEST CENTRAL IL TONIGHT. ADDITIONAL
THUNDERSTORMS SHOULD DEVELOP ON OUTFLOWS OF THE EXISTING SYSTEM
AND SHOULD AFFECT PIA AROUND 01Z AND 02Z AT BMI. STORMS COULD TAKE
A TURN TO THE SOUTH TONIGHT SO THUNDERSTORMS SHOULD GET INTO
SPI/DEC/CMI AROUND 04Z. SHORT TERM MODELS STILL DO NOT SEEM TO
HAVE GOOD HANDLE ON CURRENT TRENDS. SO WILL JUST HAVE VCTS IN
FORECAST FOR TONIGHT AND LET LATER SHIFTS DECIDE ON TIMING OF
TEMPO GROUPS. WINDS WILL BECOME A LITTLE BIT SOUTHWESTERLY AND
INCREASE IN SPEED TODAY...THEN TAPER OFF AGAIN DURING THE EVENING.
AUTEN
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
656AM CDT THU MAY 3 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
FORECAST CONCERN INVOLVES THE ONGOING CONVECTION ASSOCIATED WITH A
DYING MCS MOVING ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA
THIS MORNING. LATEST HRRR (05Z RUN) HAS CONVECTION DISSIPATING AND
MOVING EAST THROUGH 15Z AND THE 00Z 4KM WRF HAS CONVECTION
DISSIPATING BY AROUND 18Z IN EASTERN PORTIONS OF THE FORECAST AREA.
Q2 CURRENTLY DEPICTING RAINFALL RATES AROUND 2 IN/HR OR LESS WITHIN
THE STRONGER CORES...BUT LINE IS MOVING FAIRLY PROGRESSIVE AT
30-35KTS. SO NOT ANTICIPATING MUCH FLOODING ISSUES...ESPECIALLY
FURTHER EAST WITHIN THE FLASH FLOOD WATCH AREA IN NORTHEAST IOWA.
CONVECTION SHOULD BE MUCH WEAKER BY THE TIME IT REACHES IT AND
THUS...WENT AHEAD AND CANCELLED FLASH FLOOD WATCH.
OTHER CONCERN IS WITH POTENTIAL FOR AFTERNOON CONVECTION ALONG AND
SOUTH OF THE BOUNDARY IN NORTHERN IOWA. RUC/NAM/GFS ALL KEEP THE
SURFACE FRONT LAID UP ALONG THE MN/IA BORDER KEEPING THE FORECAST
AREA WITHIN THE WARM SECTOR. BEST INSTABILITY WILL BE LOCATED SOUTH
OF HIGHWAY 30 WHERE LOW LEVEL CAPE INCREASES TO AROUND 2000-3000
J/KG BUT LOW LEVEL SHEAR VALUES NOT IMPRESSIVE. CLOUDS LEFTOVER FROM
DYING MCS SHOULD LIMIT SOME OF THE DAYTIME HEATING...BUT THINKING
THE WAA WILL BE STRONG ENOUGH TO BUMPED TEMPS BACK INTO THE LOWER
80S BY THIS AFTERNOON. TIMING OF AFTERNOON CONVECTION LOOKS TO BE
AFTER 21Z WITH MID-LEVEL SHORTWAVE MOVING INTO WESTERN IOWA BY 00Z
FRIDAY. SURFACE DEW POINTS REMAIN WELL INTO THE 60S...SO PLENTY OF
MOISTURE AVAILABLE.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
CURRENT LONG WAVE PATTERN...WRN CONUS TROUGH/ERN RIDGE...WILL REMAIN
INTACT THROUGH MUCH OF THE PERIOD BUT WITH SLOW PROGRESS. THIS
SHOULD HAVE TROUGH ONLY REACH CENTRAL CONUS BY EARLY NEXT WEEK.
EXPECT CONVERGENCE FROM CURRENT NE TO MN FRONTAL BOUNDARY AND/OR
OUTFLOW FROM WEAKENING WRN IA MCS TO EVENTUALLY POSITION ITSELF INTO
CENTRAL/SRN IA BY EARLY THIS EVENING AND TRIGGER ANOTHER ROUND OF
CONVECTION...TIMED MUCH LIKE PAST FEW EVENTS MAINLY AT NIGHT. MCS
SHOULD THEN PUSH TO THE SOUTH AND EAST DIMINISHING POPS OVERNIGHT.
CONFIDENCE IN THIS SCENARIO IS SOMEWHAT LOW HOWEVER AS CURRENT MCS
CONTINUES TO BACK BUILD ACROSS SRN NE. FORECASTING EVENTUAL
POSITION OF SYNOPTIC AND/OR MESOSCALE BOUNDARIES WILL BE DIFFICULT.
BY FRI MODEL CONSENSUS SUGGESTS A RELATIVE LULL WITH IA IN FAIRLY
WEAK SELY SURFACE FLOW. STILL UNSTABLE BUT LITTLE FOCUS. ATTENTION
TURNS TO THE WEST AGAIN EYING RESPONSE TO GRADUALLY APPROACHING
WRN TROUGH. THIS WILL LEAD TO INCREASING WARM ADVECTION AND
BAROCLINICITY THROUGH SIOUXLAND MO VALLEY REGION. 305K FLOW IS
FAIRLY WEAK SO DO NOT EXPECT SIGNIFICANT MCS BUT INCREASING POPS.
CONVECTION MAY BE MORE SIGNIFICANT BY SAT NIGHT AND SUNDAY HOWEVER
AS FLOW AND ASSOCIATED THETA-E ADVECTION INCREASE. KINEMATIC
FORCING WILL INCREASE AS WELL AS LOBE OF UVM PUSHES ACROSS NRN
PLAINS INTO EARLY SUN WHICH IS ALSO FOCUSED BY PASSAGE OF INVERTED
SURFACE TROUGH. THIS ALL LEADS TO POPS BACK UP INTO LIKELIES DURING
THIS PERIOD.
BY EARLY NEXT WEEK PATTERN WILL SHIFT SUFFICIENTLY TO LOWER OUR
PRECIP CHANCES AND COOL TEMPS SOMEWHAT AS IA ENDS UP IN NWLY SURFACE
FLOW. THIS RESULTS IN EXTENDED FORECAST EITHER DRY OR WITH ONLY
SLIGHT CHANCES AND MAXES ONLY IN THE 60S OR POSSIBLY LOWER 70S.
&&
.AVIATION...03/12Z
CONVECTION DIMINISHING ACROSS CENTRAL IOWA THIS MORNING WITH GRAVITY
WAVE CAUSING SOME GUSTY WINDS ACROSS NORTHERN IOWA. WINDS SHOULD
SHIFT AROUND TO THE SOUTH ONCE RAIN/TSRA DIMINISH AND BUFR SOUNDINGS
HAVE ENOUGH MIXING TO WARRANT GUSTS IN THE UPPER TEENS THROUGH THE
DAY. LOW CONFIDENCE WITH TIMING OF CONVECTION THIS
AFTERNOON/EVENING...AND ONLY HAVE VCTS MENTIONED AT OTM/DSM ATTM
WITH THE BOUNDARY DRIFTING SOUTH. DECENT CHANCE FOR SOME FOG
DEVELOPMENT OVERNIGHT INTO FRIDAY MORNING AND HAVE MVFR VIS MENTION
FOR ALL TAF SITES EXCEPT DSM.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KLP
LONG TERM...BSS
AVIATION...KLP
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
614 AM CDT THU MAY 3 2012
...UPDATED AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 234 AM CDT THU MAY 3 2012
THE 03.00Z 250 HPA SYNOPTIC MAP SHOWED A SEGMENTED POLAR JET WITH A
90 KT JET PUSHING ASHORE ACROSS THE PACIFIC NORTHWEST. ANOTHER 110
KT JET STREAK WAS LOCATED ACROSS THE NORTHERN PLAINS WITH THE RIGHT
ENTRANCE REGION FAIRLY CLOSE TO KANSAS (AND COULD HAVE BEEN PARTIALLY
RESPONSIBLE FOR CONVECTION EARLIER). ANOTHER 100 KT JET WAS LOCATED
ACROSS NEW ENGLAND. AT 500 HPA, VERY COLD TEMPERATURES OF -25 TO -31
DEG C WERE OBSERVED ACROSS BRITISH COLUMBIA AND EXTENDING EASTWARDS
ACROSS THE CANADIAN PRAIRIES AND AS FAR SOUTH AS NORTHEASTERN MONTANA.
SEVERAL MID LEVEL SHORTWAVE TROUGH WERE ANALYZED ACROSS THE CONUS MID
ATMOSPHERE. CLOSER TO KANSAS AND IN THE LOWER LEVELS, A WARM AND DRY
PLUME (EML) EXTENDED ACROSS THE KANSAS AND SOUTHWARD INTO THE SOONER/LONE
STAR STATES. AT THE SURFACE, A LOW PRESSURE CENTER WAS LOCATED ACROSS
FAR SOUTHWESTERN KANSAS. A DRYLINE ASSOCIATED WITH THIS SURFACE LOW
EXTENDED ACROSS SOUTHWEST KANSAS AND SOUTHWARD INTO TEXAS. DEWPOINTS
IN THE 60S DEG F WERE EAST OF THIS BOUNDARY. A WEAK COLD FRONT WAS PUSHING
ACROSS EAST CENTRAL COLORADO AND INTO NORTHWEST KANSAS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 234 AM CDT THU MAY 3 2012
THIS MORNING:
A COLD FRONT IS MOVING ACROSS NORTHWESTERN KANSAS EARLY THIS MORNING.
THIS FRONT WILL MAKE ITS WAY AT LEAST THROUGH 2/3RD`S OF THE REGION
AND STALL ROUGHLY FROM MEADE TO LARNED. HRRR INDICATES SOME POST FRONTAL
STRATUS VIA UPSLOPE FLOW ACROSS INTERSTATE 70 SO HAVE INCREASED CLOUD
COVER AS A RESULT DURING THE MORNING FOR THIS AREA. TODAY WILL START
OUT QUITE MILD AS DEWPOINTS EAST OF THE DRYLINE ARE WELL INTO THE 60S
DEG F. THIS WAS UNDER FORECAST BY SEVERAL OF THE MODELS. NO PRECIPITATION
IS EXPECTED ALONG THE FRONTAL BOUNDARY DUE TO SUBSIDENCE ALOFT/NO UPPER
LEVEL SUPPORT.
TODAY:
THE HOTTEST TEMPERATURES ARE LIKELY SOUTH OF THE FRONTAL WHICH WILL
STALL ACROSS THE AFOREMENTIONED MEADE TO LARNED LINE. LOW TO MID 90S
DEG F ARE POSSIBLE ACROSS SOUTH CENTRAL KANSAS. FURTHER NORTHWEST, THERE
WILL BE ENOUGH INSOLATION AND MIXING TO ALLOW TEMPERATURES TO PEAK INTO
THE MID TO UPPER 80S DEG F.
THIS EVENING:
I HAVE COMPROMISED BETWEEN SEVERAL MODELS AND HAVE SLIGHT POPS ROUGHLY
NORTHWEST FROM A HAYS TO ELKHART LINE. 00Z NAM/WRF/NMM ARE IN FAIRLY
GOOD AGREEMENT WITH THE POSSIBILITY OF UPSLOPE AND FRONTAL RELATED CONVECTION
ACROSS SOUTHEASTERN COLORADO INTO FAR SW/W KANSAS. THE GFS IS A BIT
DIFFERENT WITH BETTER CONVECTIVE CHANCES ALONG INTERSTATE 70. AS A RESULT,
HAVE BLENDED POPS BETWEEN THE MODELS. THERE MAY BE A WEAK MID LEVEL
SHORTWAVE TROUGH AS SEEN ACROSS THE ROCKIES EARLY THIS MORNING THAT
COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT FOR THUNDERSTORMS. OTHERWISE,
UPPER LEVEL SUPPORT TODAY IS QUITE WEAK. FORECAST SOUNDINGS ACROSS
FAR WESTERN KANSAS SHOW ABOUT 1500 J/KG OF CAPE AND A BIT OF VEERING
IN THE WIND PROFILE, ALTHOUGH SPEED SHEAR IS RATHER WEAK. THE THERMODYNAMIC
PROFILE IS WELL MIXED TO ABOUT 600 HPA SO IF CONVECTION DOES FORM, THEN
DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT AND PERHAPS MARGINAL SEVERE
HAIL SINCE 0 TO 6 KM SHEAR IS ONLY FORECAST TO BE ABOUT 25-30 KT. WITH
THIS EXCEPTION OF A VERY MARGINAL CHANCE OF AN ISOLATED THUNDERSTORM,
THE FORECAST WILL REMAIN DRY. OVERNIGHT LOWS HEADING INTO FRIDAY MORNING
WILL BE MILD AGAIN WITH 50S DEG F TOWARDS GARDEN CITY AND 60S DEG F
TOWARDS MEDICINE LODGE DUE TO MODERATE DEWPOINTS AND WEAK LEE TROUGH/RESULTANT
SOUTHERLY WINDS THROUGH THE OVERNIGHT PERIOD.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 309 AM CDT THU MAY 3 2012
BOTH THE NAM AND GFS ARE IN GOOD AGREEMENT WITH A SUBTLE UPPER
LEVEL DISTURBANCE CROSSING SOUTHWEST KANSAS EARLY IN THE DAY ON
FRIDAY. AS THIS SYSTEM CROSSES WESTERN KANSAS A SURFACE BOUNDARY
WILL EXTEND FROM WEST TO EAST NORTH OF INTERSTATE 70 AND A DRYLINE
IS EXPECTED TO STRETCH FROM THIS SURFACE BOUNDARY SOUTH INTO
WESTERN OKLAHOMA. AT THIS TIME BASED ON THE TIMING OF THIS SUBTLE
FEATURE AND WARM MID LEVEL TEMPERATURES FORECAST FRIDAY AFTERNOON
WILL CONTINUE TO FAVOR A DRY FORECAST FRIDAY AND FRIDAY NIGHT
ACROSS WESTERN KANSAS. MODEL SOUNDINGS INDICATING A DECENT MIXING
DEPTH AND BASED ON 850MB TEMPERATURES AT 00Z SATURDAY WILL
CONTINUE TO FAVOR HIGHS AT LEAST IN THE LOW TO MID 90S.
A STRONGER UPPER LEVEL TROUGH WILL BEGIN TO CROSS WESTERN UNITED
STATES LATE FRIDAY. AN UPPER LEVEL JET IS FORECAST TO BEGIN TO
MOVE FROM THE BASE OF THIS TROUGH AND EJECT OUT INTO THE WEST
CENTRAL HIGH PLAINS BY EARLY THIS WEEKEND. AS THIS NEXT SYSTEM
APPROACHES EARLY THIS WEEKEND AN AREA OF LOW PRESSURE IS EXPECTED
TO DEEPEN ACROSS EASTERN COLORADO/WESTERN KANSAS. BY 00Z SUNDAY
700MB TEMPERATURES ACROSS WESTERN KANSAS ARE FORECAST TO RANGE
FROM +10 TO +12C AND THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL
JET IS EXPECTED TO BE LOCATED NEAR NORTHEAST COLORADO. BASED ON
THE LOCATION OF THE UPPER JET, 925-850MB THTA-E RIDGE
AXIS/MOISTURE ADVECTION AND NORTHERN EDGE OF THE WARM 700MB
TEMPERATURES WILL FAVOR LATE DAY AND EARLY SATURDAY NIGHT
CONVECTION STAYING NORTH OF THE AREA. TEMPERATURES SATURDAY WILL
ONCE AGAIN BE WARM AND BASED ON 850MB TEMPERATURES AND THE
FORECAST MIXED LAYER THE HIGHS SATURDAY AFTERNOON SHOULD CLIMB
ONCE AGAIN BACK INTO THE LOW TO MID 90S.
BY EARLY SUNDAY THE UPPER JET WILL MOVE OUT INTO THE NORTHERN
PLAINS AND A COLD FRONT IS FORECAST TO SURGE SOUTH INTO WESTERN
KANSAS. A TIGHT SURFACE PRESSURE GRADIENT AND STRONG BOUNDARY
LAYER TO 850MB WINDS ARE FORECAST BEHIND THIS FRONT WITH A NET 24
HOUR 850MB TEMPERATURE CHANCE FROM 00Z SUNDAY TO 00Z MONDAY
AVERAGING FROM 8-12C DEGREES COOLER. AS A RESULT WILL UNDERCUT MAX
TEMPERATURES ON SUNDAY AND TREND TOWARDS THE COOLER 00Z MONDAY
ECMWF/GFS 850MB MIX DOWN TEMPERATURES. MOISTURE SOMEWHAT LIMITED
WITH THIS FRONT AND UPPER LEVEL DYNAMICS APPEAR TO REMAIN NORTH OF
THE AREA SO PRECIPITATION CHANCES STILL APPEAR SMALL BUT DID
INSERT SOME SMALL POPS EARLY SUNDAY NEAR AND NORTH OF INTERSTATE
70.
ON MONDAY ISENTROPIC LIFT/850-700MB WARM AIR ADVECTION BEGINS TO
IMPROVE ACROSS EASTERN COLORADO AND WESTERN KANSAS. ON MONDAY
NIGHT ANOTHER UPPER LEVEL TROUGH WILL BEGIN TO APPROACH THE WEST
CENTRAL PLAINS WHICH SHOULD PROVIDE THE NEXT DECENT OPPORTUNITY
FOR MEASURABLE PRECIPITATION TO PORTIONS OF WESTERN KANSAS TUESDAY
AND WEDNESDAY AS MOISTURE AND ISENTROPIC LIFT/WARM AIR ADVECTION
CONTINUES ACROSS WESTERN KANSAS. IN ADDITION GIVEN THE CLOUD COVER
EXPECTED TUESDAY AND WEDNESDAY WILL CONTINUE TO FAVOR THE PREVIOUS
FORECAST WITH HIGHS MAINLY IN THE UPPER 60S TO LOWER
70S...ESPECIALLY ON TUESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 604 AM CDT THU MAY 3 2012
A WEAK COLD FRONT EXTENDED FROM HAYS TO DODGE CITY AS OF 10Z WITH
LOW CLOUDS DEVELOPING BEHIND THIS FRONT BASED ON THE 11-3.9
SATELLITE LOOP. THE LATEST SATELLITE TRENDS APPEARS TO SUPPORT THE
06Z BUFR SOUNDINGS IN PLACING HAYS IN THE AREA WHERE THE MVFR STATUS
WILL LINGER FOR A COUPLE OF HOURS EARLY THIS MORNING. ELSEWHERE VFR
CONDITIONS ARE ANTICIPATED. THE NORTHERLY WINDS BEHIND THIS FRONT
IS EXPECTED TO GRADUALLY VEER BACK TO THE EAST BY LATE DAY WITH
WIND SPEEDS AVERAGING 10 KNOTS OR LESS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 88 56 95 61 / 10 10 0 0
GCK 86 55 94 58 / 10 20 0 0
EHA 89 56 94 59 / 20 20 0 0
LBL 89 58 96 60 / 10 10 0 0
HYS 85 60 93 62 / 10 20 0 10
P28 93 66 93 66 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SUGDEN
SHORT TERM...SUGDEN
LONG TERM...BURGERT
AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
704 AM CDT THU MAY 3 2012
...UPDATE...
UPDATED FOR 12Z AVIATION DISCUSSION BELOW
&&
.DISCUSSION...
NUMEROUS THUNDERSTORM COMPLEXES TRACKED ACROSS THE MIDWEST AND THEIR
OUTFLOW BOUNDARIES HAVE POLLUTED ANY ATTEMPT AT A CLEAN SURFACE
ANALYSIS. JUST LOOKING AT THE DEWPOINTS AND WIND FIELD ON THE LARGE
SCALE...IT APPEARS THE PARENT BOUNDARY REMAINS ACROSS THE NORTHERN
HALF OF THE CWA. THIS BOUNDARY WILL ONCE AGAIN BE THE FOCUS FOR
SHOWERS AND THUNDERSTORMS LATER TODAY.
TODAY...THE TWO OBVIOUS MCS PER IR SATELLITE IMAGERY ARE LOCATED TO
THE EAST AND SOUTH OF THE CWA. MEANWHILE A SMALLER LESS ORGANIZED
COMPLEX OF SHOWERS AND THUNDERSTORMS WILL BE EXITING EASTERN
MINNESOTA AND ENTERING WESTERN WISCONSIN. THERE SHOULD BE SOME
CLEARING FROM WEST TO EAST AND A DRY START TO THE DAY TODAY AS THESE
SHOWERS AND THUNDERSTORMS EXIT THE REGION. LATEST WV IMAGERY WITH
500MB HEIGHTS SHOWS ELONGATED SHORTWAVE TROUGH ACROSS THE
MONTANA/DAKOTA BORDER. NUMERICAL MODELS TRACK THIS SHORTWAVE NORTH
OF LAKE SUPERIOR TODAY...AND WEAK RIDGING/SUBSIDENCE IN THE WAKE OF
THIS WAVE WILL DEVELOP A SURFACE HIGH THAT WILL ATTEMPT TO PUSH THE
STATIONARY BOUNDARY SOUTH OF THE REGION THROUGHOUT THE DAY TOWARD
THE EVENING HOURS. HAVE A LITTLE TROUBLE BUYING THE SOUTHERN EXTEND OF
THE BOUNDARY PROGRESSION...ESPECIALLY WITH ZONAL FLOW ALOFT. IF THE
BOUNDARY DOES FAIL TO SLIDE SOUTHEAST OF THE REGION AS CURRENTLY
FORECAST...THE PROBABILITY OF LATE AFTERNOON THUNDERSTORMS WOULD
INCREASE. THE AIRMASS ALONG AND SOUTH OF THE BOUNDARY IS
CHARACTERIZED BY ABUNDANT LOW LEVEL MOISTURE...AND WILL QUICKLY
DESTABILIZE WITH AND AMOUNT OF SOLAR INSOLATION TODAY. LOW LEVEL
WIND FIELDS ARE LESS IMPRESSIVE THAN WEDNESDAYS....BUT EVEN
MARGINAL DEEP LAYER SHEAR OF 30-40KTS WITH 2000J/KG OF CAPE WOULD
SUPPORT SUPERCELLS CAPABLE OF PRODUCING SEVERE HAIL AND POSSIBLY
DAMAGING WINDS. LATEST SPC DAY 1 OUTLOOK SLIGHT RISK AREA JUST
CLIPS THE FAR SOUTHERN PORTION OF THE CWA. HOWEVER...BOTTOM LINE
IS THE PROGRESSION OF THE BOUNDARY WILL HAVE TO BE MONITORED TO
ADD CONFIDENCE TO THE TIMING AND PLACEMENT OF PRECIP/SEVERE THREAT
LATER THIS AFTERNOON. FLASH FLOODING WILL ALSO HAVE TO MONITORED
IF TRAINING THUNDERSTORMS DEVELOP.
FRIDAY THROUGH WEDNESDAY...ASSUMING THE BULK OF THE PRECIP REMAINS
SOUTHEAST OF THE REGION THURSDAY NIGHT...WILL START OFF DRY FOR
FRIDAY BEFORE ANOTHER WAVE DEVELOPS SOME SHOWERS AND THUNDERSTORMS
AND SPREADS THEM ACROSS THE REGION FROM WEST TO EAST. LOOKS LIKE
CHANCES FOR PRECIP WILL LAST THROUGH SUNDAY...WITH THE HIGHEST CHANCE
SATURDAY NIGHT INTO SUNDAY MORNING AS THE MOST POTENT WAVE IN THIS
SHORTWAVE-TRAIN MOVES ACROSS THE REGION. AS THIS POSITIVELY TILTED
WAVE PASSES THROUGH...THE PATTERN WILL AMPLIFY AND WE WILL
TRANSITION FORM ZONAL WEST/EAST FLOW...TO MORE OF A NORTHWEST FLOW.
THIS WILL BRING DRIER WEATHER AND COOLER TEMPERATURES THROUGH THE
MIDDLE OF NEXT WEEK.
&&
.AVIATION.../12Z TAF ISSUANCE/
WEAK BOUNDARY CONTINUES TO MAKE THIS A FORECASTING CHALLENGE.
OVERNIGHT CONVECTION HAS MADE IDENTIFYING THE WEAK BOUNDARY A TAD
MORE DIFFICULT.
A WEAK LOW PRESSURE AREA LOCATED ALONG THE MN/SD
BORDER HAS A BOUNDARY EXTENDING EAST TOWARD NORTHERN WISCONSIN.
THIS BOUNDARY HAS BEEN THE FOCUS OF PAST AND ONGOING CONVECTION.
THE OVERALL SOLUTION TODAY WILL BE TO SLOWLY PUSH THE BOUNDARY
SOUTH TOWARD THE MN/IA BORDER BY TONIGHT. VARIOUS SOLUTIONS PUSH
THE BOUNDARY SOUTH SOONER AND HAVE DIFFERENT PRECIPITATION
SCENARIOS. THIS WILL MAKE FOR A CHALLENGING CONVECTION AND WIND
FORECAST. THE RAP IS FASTER AND MORE AGGRESSIVE THAN THE NAM. BOTH
OF WHICH BRING DRIER AIR INTO MUCH OF THE AREA LATER THIS
AFTERNOON. THE 03Z HRRR HAD A GOOD HANDLE ON THE CONVECTION
HOWEVER SUBSEQUENT RUNS HAVE BEEN CHALLENGED. AS A RESULT I AM NOT
OVERLY CONFIDENT OF THE FORECAST. AS A RESULT HAVE FAIRLY
OPTIMISTIC TAFS AND THEY WILL HAVE TO BE WATCHED CLOSELY. REALLY
BELIEVE MOST OF THE CONVECTION WILL BE IN THE SOUTHERN PART OF OUR
AREA AND WILL NOT IMPACT ANY OF THE MN TERMINALS. COULD SEE MORE OF
AN IMPACT AT KEAU LATE THIS AFTERNOON.
KMSP...BOUNDARY APPEARS TO BE JUST NORTH OF THE AIRFIELD AND
WILL MOVE SOUTH OF THE AIRFIELD LATER THIS AFTERNOON. DEPENDING ON
TIMING OF THE BOUNDARY PASSAGE IT IS POSSIBLE THAT THE AIRPORT
WILL SEE NO THUNDERSTORM ACTIVITY. THIS WILL BE MONITORED CLOSELY.
OUTLOOK...EVEN AFTER THE BOUNDARY MOVES TOWARD IOWA WE HAVE SOME
RESIDUAL MOISTURE IN PLACE WITH SOME PERIODS OF INSTABILITY
THEREFORE CAN EXPECT TO SEE CHANCES OF CONVECTION FOR THE NEXT FEW DAYS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JRB/DRL
AREA FORECAST DISCUSSION
NWS BILLINGS MT
924 AM MDT THU MAY 3 2012
.SHORT TERM...VALID FOR TDY AND FRI...
WEAK SHORTWAVE MOVING THROUGH THE AREA NOW DID PRODUCE SOME LIGHT
PCPN OVER THE MOUNTAINS BUT NOTHING MORE THAN SOME MID CLOUD
ACROSS LOWER ELEVATIONS. THIS AREA OF MID CLOUD IS SPREADING TO
SOUTHEAST MONTANA NOW AND WILL EXIT OVER THE COMING HOURS...
ALLOWING FOR INCREASED SUNSHINE IN ITS WAKE. NEXT APPROACHING
SHORTWAVE ALONG THE PAC NW COAST IS SOMEWHAT STRONGER AND FORCING
FROM THIS FEATURE WILL INCREASE THIS AFTERNOON. IT APPEARS THAT
JET DIVERGENCE WILL BE GREATEST IN OUR NW SO HIGHEST POPS THERE
LOOK GOOD THIS AFTERNOON. ONSET OF LOW LEVEL EAST THEN SOUTHEAST
FLOW WILL RESULT IN VERY MODEST MOISTURE RETURN AS THE DAY WEARS
ON. EVEN WITH THIS...CAPE VALUES WILL REMAIN MEAGER AT 100-200
JOULES OR LESS...SO NOT SEEING MUCH LIGHTNING POTENTIAL TODAY.
LATEST NAM AND HRRR DO SHOW SOME WEAK CONVECTION IN OUR FAR
SOUTHEAST BY THIS EVENING...IN LINE WITH THE INCREASED MOISTURE
AND WEAK SFC TROF...SO SCATTERED POPS EXTENDING ACROSS OUR
SOUTHEAST THIS EVENING ALSO LOOK GOOD. SHOWER CHANCES WILL
DIMINISH LATE TONIGHT AS WAVE PASSES. TEMPS TODAY WILL TURN A FEW
DEGREES WARMER THAN YESTERDAY WITH SOME PREFRONTAL HEATING AHEAD
OF THIS EVENINGS WAVE. LOOKING FOR HIGHS INTO THE 60S TO NEAR 70.
JKL
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
EXTENDED MODELS LOOK TO BE IN GOOD AGREEMENT OVERALL THROUGH THE
FIRST PORTION OF THE EXTENDED PERIOD. BOTH THE GFS AND ECMWF
SWING AN UPPER LEVEL TROUGH ACROSS MONTANA ON SATURDAY WITH THE
UPPER LOW MOVING ACROSS THE NORTHERN PORTIONS OF THE STATE. AT
THE SAME TIME...A SURFACE LOW ACROSS EASTERN COLORADO WILL EXTEND
NORTHWARD INTO WESTERN NORTH DAKOTA. THE NORTHERN PORTION OF THIS
AREA OF LOW PRESSURE WILL CUT OFF AND STRENGTHEN OVER SOUTHERN
CANADA WHILE THE UPPER LOW CUTS OFF AND DEEPENS OVER THE SAME AREA.
THIS ALL RESULTS IN AN OVERALL COOL AND SHOWERY WEEKEND. PRESSURE
GRADIENTS WILL BE TIGHT ACROSS THE EASTERN HALF OF THE STATE SO
EXPECT GUSTY NORTHWEST WINDS SATURDAY AND SUNDAY AS WELL. THE
STRONGEST WIND GUSTS WILL BE EAST OF BILLINGS...ESPECIALLY TOWARD
THE DAKOTA BORDER. BEST CHANCES FOR SHOWERS WILL BE THE FAVORED
AREAS WITH NORTHWEST SURFACE WINDS...MAINLY FROM BILLINGS
EASTWARD. TEMPERATURES WILL BE AT OR SLIGHTLY BELOW NORMAL FOR THE
WEEKEND...AND GIVEN COOL TEMPERATURES...NOT EXPECTING MUCH IN THE
WAY OF THUNDERSTORM ACTIVITY AT THIS TIME.
NORTHWEST FLOW ALOFT CONTINUES MONDAY WITH LINGERING SHOWER
CHANCES...ALTHOUGH LESS CHANCES THAN SATURDAY AND SUNDAY. BOTH
THE GFS AND ECMWF SHOW HIGH PRESSURE RIDGING RETURNING TOWARD THE
MIDDLE TO END OF NEXT WEEK RESULTING IN WARMER AND DRIER
CONDITIONS. HOWEVER...TIMING IS OFF WITH MODELS AS TO HOW QUICKLY
THIS RIDGE BUILDS OVER OUR FORECAST AREA. HOOLEY
&&
.AVIATION...
EXPECT PARTLY TO MOSTLY CLOUDY SKIES TODAY. A FEW SHOWERS WILL BE
POSSIBLE OVER THE MOUNTAINS THIS MORNING BUT THE LOWER ELEVATIONS
ARE EXPECTED TO BE DRY. HOWEVER...SHOWER AND ISOLATED
THUNDERSTORM CHANCES INCREASE THIS AFTERNOON FROM KBIL WESTWARD
WITH THE BEST CHANCES OVER THE MOUNTAIN LOCATIONS. VFR CONDITIONS
WILL PREVAIL TODAY WITH MVFR CONDITIONS IN ANY SHOWER ACTIVITY.
THE MOUNTAINS WILL BE OBSCURED AT TIMES THROUGHOUT THE DAY.
HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
TDY FRI SAT SUN MON TUE WED
-------------------------------------------------------
BIL 066 044/069 045/063 042/059 040/058 038/062 039/067
2/W 33/T 34/T 33/W 23/W 22/W 21/B
LVM 063 039/063 036/059 034/055 032/054 030/059 031/064
4/T 34/T 44/T 33/W 34/W 22/W 21/B
HDN 069 043/073 044/065 042/062 041/060 038/064 039/068
1/B 33/T 34/T 33/W 23/W 22/W 21/B
MLS 070 047/073 046/065 042/061 040/060 040/065 040/068
1/B 43/T 34/T 43/W 23/W 22/W 11/B
4BQ 069 045/072 044/065 042/061 039/059 037/063 040/066
1/B 33/T 44/T 43/W 13/W 22/W 11/B
BHK 067 047/072 046/065 042/060 040/058 040/062 040/066
0/B 42/T 34/T 43/W 22/W 22/W 11/B
SHR 067 041/070 041/062 037/058 037/055 033/058 036/063
1/B 33/T 24/T 42/W 24/W 22/W 21/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1045 AM EDT THU MAY 3 2012
.SYNOPSIS...
STRONG UPPER LEVEL HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH
THE WEEK. A COLD FRONT WILL DROP SOUTH THROUGH THE AREA LATE
SATURDAY AND INTO SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM THURSDAY...
HAVE BEEN MONITORING THE SOUTHWEST ADVANCEMENT OF A LOW STRATUS/FOG
SHIELD ACROSS SOUTHEAST AND SOUTHERN VIRGINIA INTO NORTHEAT NC. THIS
FEATURE HAD BEEN MAKING STEADY PROGRESS TO THE SOUTHWEST FOR SEVERAL
HOURS AND HAS REACHED HALIFAX AND WARREN COUNTIES. RECENT SAT TRENDS
SUGGEST THAT THE SW PUSH HAS SLOWED AND THE CLOUDS/FOG MAY HAVE
REACHED THEIR FURTHEST SOUTHWARD EXTENT. THIS FEATURE WAS NOT WELL
PROGGED BY THE NAM/GFS BUT RECENT RUNS OF THE RAHWRFARW AND
ESPECIALLY THE HRRR PICKED UP ON THIS FEATURE. EXPECT THE CLOUDS TO
HOLD FOR A FEW MORE HOURS WHERE THEY HAVE REACHED BUT NOT MOVE TOO
MUCH FURTHER SW.
THE 12Z KGSO RAOB PROVIDES A 1000-850 THICKNESS OF 1408M OR 4M
GREATER THAN 12Z WED. 850MB TEMPS WARMED 3DEG C FROM 12Z WED.
700MB HEIGHTS AT KGSO REACHED 3205M WHICH ALL SUPPORT VERY WARM
AFTERNOON HIGHS ABOUT 2 DEGREES WARMER THAN WED. THIS SHOULD RESULT
IN NEAR RECORD HIGHS OF 90-93 DEGREES TODAY.
THREAT OF CONVECTION TODAY IS RATHER LIMITED WITH THE LACK OF
FORCING MECHANISMS. ONE DISTURBANCE OVER SOUTHEAST VA WHICH SHOWS UP
WELL IN THE 1.5PV ANALYSIS SHOULD REMAIN NORTHEAST OF OUR AREA
THROUGH THE AFTERNOON. ANOTHER DISTURBANCE ELONGATED NORTH-SOUTH
ACROSS THE TN VALLEY WILL SHIFT TOWARD THE MOUNTAINS THIS EVENING.
THE BEST FORCING FOR ASCENT WITH THIS FEATURE SHOULD REMAIN ACROSS
THE MOUNTAINS. DIFFERENTIAL HEATING BOUNDARY ASSOCIATED WITH THE
PREVIOUSLY NOTED CLOUD SHIELD COULD ALSO FOCUS CONVECTION. WOULD NOT
BE SURPRISED TO SEE AN ISOLATED STORM MOVE FROM THE FOOTHILLS INTO
THE NORTHERN PIEDMONT OR OTHER ISOLATED ACTIVITY LATE THIS AFTERNOON
IN THE NORTHERN TIER BUT THE COVERAGE IS EXPECTED TO BE SO LIMITED
WE WILL OMIT POPS.
THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS WILL BRING A SLIGHT
REPRIEVE ON FRIDAY AND FRIDAY NIGHT WITH H7 HEIGHTS FALLING 60-70
METERS WITH H8 TEMPS COOLING OFF TO 15 TO 16C. ADDITIONALLY...AS
PLUME OF TROPICAL MOISTURE SURGES NORTHWARD INTO THE AREA(PWATS +2SD
ABOVE NORMAL...1.5-1.7")...EXPECT CLOUDY TO MOSTLY CLOUDY SKIES AND
THE PROSPECTS OF CONVECTION TO GREATLY LIMIT HEATING. WILL LOWER
FORECAST HIGHS INTO THE MID TO UPPER 80S...BUT COULD CONCEIVABLY BE
COOLER...MORE IN THE WAY IN THE LOWER TO MID 80S IF THE CONVECTION
MOVES/DEVELOPS EARLY ENOUGH. MILD OVERNIGHT LOWS GENERALLY IN THE
MID 60S.
WILL KEEP A DRY FORECAST FOR TONIGHT WITH BROAD ANTICYCLONIC FLOW
AND ASSOCIATED SUBSIDENCE THE RULE. RAIN CHANCES RETURN ON FRIDAY
WITH THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS MOVING THROUGH
THE AREA DURING PEAK AFTERNOON HEATING PROVIDING THE FOCUS FOR
SCATTERED SHOWERS AND THUNDERSTORM FRIDAY AFTERNOON AND INTO THE
EARLY EVENING BEFORE THE WAVE SHIFTS EAST OF THE AFTER MIDNIGHT.
WHILE MODELS SHOW MODERATE INSTABILITY ACROSS THE AREA FRIDAY
AFTERNOON...WIND SHEAR IS VERY WEAK...10 TO 15KTS. THUS DO NOT
EXPECT MUCH IN THE WAY OF SEVERE. HOWEVER...DUE TO HIGH
PWATS...LOCALLY HEAVY RAIN IS POSSIBLE.
BLAES/CBL
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM THURSDAY...
A SURFACE LOW OVER NEW ENGLAND WILL GRADUALLY SHIFT SOUTHEAST
SATURDAY INTO SUNDAY...BRINGING A COLD FRONT AND ASSOCIATED PRECIP
CHANCES TOWARDS THE REGION. MODELS HAVE COME INTO A LITTLE BETTER
AGREEMENT WITH THEIR HANDLING OF THIS FRONT OVER THE AREA FOR THE
WEEKEND. AT THIS TIME...IT APPEARS THE FRONT SHOULD CROSS THE AREA
LATE SATURDAY INTO SUNDAY AND THEN STALL NEAR THE SOUTHWESTERN
PORTIONS OF THE FORECAST AREA BY LATE SUNDAY...WITH HIGH PRESSURE
BUILDING IN FROM THE NORTH. THEREFORE...PRECIP CHANCES SHOULD
INCREASE THROUGH THE DAY ON SATURDAY...BEFORE DECREASING FROM
NORTHEAST TO SOUTHWEST LATE SUNDAY. WE SHOULD SEE ONE MORE DAY OF
HIGHS IN THE UPPER 80S TO NEAR 90 DEGREES ON SATURDAY...BEFORE
SLIGHTLY COOLER MAX TEMPS ON SUNDAY BEHIND THE FRONT...GENERALLY LOW
TO MID 80S. SIMILAR TREND IS EXPECTED FOR OVERNIGHT LOWS...WITH
GENERALLY MID 60S EXPECTED SATURDAY NIGHT AND UPPER 50S TO LOWER 60S
EXPECTED BY SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
THE BEGINNING OF THE LONG TERM PERIOD SHOULD START MOSTLY DRY...WITH
SEASONAL TEMPS AS HIGH PRESSURE CONTINUES TO RIDGE INTO THE AREA
FROM THE NORTH. THERE WILL BE A SLIGHT CHANCE OF DIURNAL CONVECTION
ON MONDAY...ESPECIALLY ACROSS THE SOUTHWESTERN/WESTERN PORTIONS OF
THE FORECAST AREA DUE TO PROXIMITY OF A STALLED FRONT. THEN THE
SURFACE HIGH RIDGING WILL SHIFT OFFSHORE BY TUESDAY AS THE NEXT
SYSTEM APPROACHES FROM THE NORTHWEST. PRECIP CHANCES WILL INCREASE
TUESDAY INTO THE WEDNESDAY AS THE FRONT SHIFTS BACK NORTH ACROSS THE
REGION AND WARM...MOIST SOUTHERLY FLOW RETURNS TO THE AREA. ALSO...
AS THE AFOREMENTIONED SURFACE LOW PRESSURE SYSTEM TRACKS TO THE
NORTH OF THE AREA...IT TRIES TO PUSH A COLD FRONT TOWARDS THE REGION
BY MID WEEK...WHICH MAY ALSO HELP TO INCREASE PRECIP CHANCES.
HOWEVER...AS CAN BE EXPECTED DURING THIS PART OF THE FORECAST...
THERE IS TIMING AND STRENGTH DIFFERENCES IN THE MODELS...THEREFORE
WILL GO NO HIGH THAN LOW END CHANCE POPS AT THIS TIME. TEMPS WILL
GRADUALLY WARM THROUGH THE PERIOD AS RETURN FLOW SETS UP OVER THE
REGION...BUT SHOULD STAY JUST ABOVE NORMAL VALUES...GENERALLY IN THE
LOW TO MID 80S BY WEDNESDAY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 720 AM THURSDAY...
OUTSIDE OF SOME BRIEF PATCHY FOG/STRATUS THIS MORNING...STRONG HIGH
PRESSURE ALOFT WILL RESULT IN VFR CONDITIONS THROUGH THE 24 HOUR TAF
PERIOD ENDING AT 06Z FRIDAY. WINDS WILL REMAIN LIGHT AND VARIABLE.
OUTLOOK...UPPER LEVEL ISOLD TO SCATTERED AFTERNOON AND EARLY EVENING
SHOWERS AND THUNDERSTORMS WILL BE THE MAIN CONCERN THE NEXT COUPLE
OF DAYS WITH INCREASING CHANCES FOR CONVECTION INTO THE WEEKEND WITH
THE PASSAGE OF A COLD FRONT. PATCHY PREDAWN FOG/STRATUS WILL ALSO BE
POSSIBLE EACH MORNING...OTHERWISE VFR CONDITIONS
&&
.CLIMATE...
THE FOLLOWING ARE RECORD HIGH TEMPERATURES FOR THE REMAINDER OF THE
WEEK:
RDU GSO FAY
THU MAY 3RD: 93 IN 1959 92 IN 1959 95 IN 1913
FRI MAY 4TH: 94 IN 1938 94 IN 1928 97 IN 1938
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...BLAES/CBL
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...CBL
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1133 AM EDT THU MAY 3 2012
.SYNOPSIS...
A FRONT JUST NORTH OF LAKE ERIE WILL REMAIN NEARLY STATIONARY INTO
FRIDAY AS WAVES OF LOW PRESSURE MOVE ALONG THE FRONT. THE FRONT WILL
DROP SOUTHEAST ACROSS THE AREA LATER FRIDAY AND STALL NEAR THE OHIO
RIVER UNTIL A LOW SLOWLY MOVES ACROSS OHIO MONDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...BOOSTED TEMPS A BIT IN PLACES BASED ON LATEST HRRR OUTPUT.
FOR 630 AM UPDATE...ONLY CHANGE WILL BE TO LOWER POPS FOR MORNING
SINCE NOTHING OF NOTE CURRENTLY OCCURRING. ALSO WILL ADD SOME PATCHY
FOG FOR NEXT FEW HOURS.
THE AIRMASS WILL REMAIN UNSTABLE TODAY. A LOW LEVEL JET WILL
CONTINUE TO BRING MOISTURE INTO THE CWA FROM THE SW WHILE WIND SHEAR
REMAINS RELATIVELY WEAK. THE SHORT TERM HI RES MODELS SEEM TO WANT
TO PRODUCE THE MOST CONVECTION INTO THE MORNING THEN THE NAM AND GFS
TAPER BACK THE THREAT INTO THE AFTERNOON AS THE FRONTAL CONVERGENCE
LIFTS NE OF THE AREA. WILL CONTINUE CHANCE POPS FOR TODAY WITH THE
BEST CHANCE IN THE NORTH. DUE TO THE LIMITED RISK FOR SEVERE WILL
NOT MENTION AT THIS TIME.
A VERY WARM DAY IS IN STORE WITH RECORD OR NEAR RECORD HIGHS
POSSIBLE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
THE WEAK FRONTAL BOUNDARY WILL GET PUSHED SOUTH ACROSS THE CWA FRI.
ABUNDANT MOISTURE PRESENT WITH PW`S AROUND 1.5 INCHES. EXPECT FAIRLY
WIDESPREAD SHRA/TSRA TO SPREAD SE ACROSS THE REGION WITH THE FRONT.
CLOUD COVER WILL BE MORE EXTENSIVE SO THIS SHOULD HELP TO LIMIT HIGH
TEMPS/INSTABILITY AND THUS THE SEVERE THREAT.
FRI NIGHT...THE BETTER THREAT FOR CONVECTION SHOULD BE SHIFTING INTO
THE SOUTHERN HALF OF THE CWA WITH A LINGERING CHANCE INTO SAT FOR
MAINLY THE SOUTH. EVEN THOUGH OVERALL AIRMASS REMAINS QUITE WARM ON
SAT...NE FLOW OFF OF A CHILLY LAKE ERIE WILL LIKELY KEEP TEMPS IN
THE LOW TO MID 60S DOWNWIND OF THE LAKE.
THE HIGH TO THE NORTH SHOULD PUSH ENOUGH OF A RIDGE SOUTH INTO THE
AREA TO HOLD OFF THE PRECIP THREAT FOR SAT NIGHT AND SUN BUT
OVERRUNNING IN THE SW WILL BEGIN ON SUN AND COULD ALLOW SOME
CONVECTION TO RETURN.
THE APPROACH OF A LOW WEST OF THE AREA BY DAYBREAK MON WILL PROBABLY
LEAD TO MORE CONVECTION PUSHING INTO AT LEAST THE WEST HALF OF THE
AREA SUN NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE WILL BE MOVING INTO THE REGION ON MONDAY WITH INCREASED
CHANCES OF RAIN BY AFTERNOON. THIS RAIN WILL CONTINUE INTO MONDAY
NIGHT AND MAY ACTUALLY LINGER INTO TUESDAY MORNING. MODELS ARE
DIFFERING ON HOW FAST THIS LOW WILL CLEAR THE AREA. A FRONTAL
BOUNDARY WILL NOT BE ALL THAT FAR FROM THE SOUTHERN COUNTY WARNING
AREA ON TUESDAY NIGHT BUT IT APPEARS THAT MUCH OF THE AREA WILL BE
DRY. MODELS ARE STRUGGLING ON HOW TO DIG THE NEXT TROUGH INTO THE
CENTRAL LAKES ON WEDNESDAY. THE DIFFERING SCENARIOS WOULD BE SHOWERS
RETURNING EITHER EARLY WEDNESDAY OR MAYBE HOLDING OFF UNTIL
AFTERNOON OR EVENING.
HIGHS WILL LIKELY BE ABOVE AVERAGE ON MONDAY BUT WE WILL COOL BACK
TO SEASONAL LEVELS FOR TUESDAY INTO WEDNESDAY.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
EXPECT SOME MIDDLE AND HIGH LEVEL CLOUD COVER TO VARY IN
THICKNESS THROUGH THE MORNING. BELIEVE THERE WILL AT LEAST BE A
FEW PATCHES OF MVFR FOG...ESPECIALLY WHERE IT RAINED OVERNIGHT.
CANT COMPLETELY RULE OUT A SHOWER OR TWO DEVELOPING WITH THE
MORNING MIX. IF THESE DO OCCUR THEY WILL BE VERY BRIEF. SOUTHWEST
WINDS WILL BECOME GUSTY BY AFTERNOON. GUSTS IN THE 25 KNOT RANGE
WILL BE COMMON WITH A FEW LOCATIONS ACROSS NW OHIO AROUND 30
KNOTS.
THE ATMOSPHERE WILL BE UNSTABLE AGAIN THIS AFTERNOON BUT THERE
MAY NOT BE ANY BOUNDARIES TO GET THE CONVECTION STARTED. CANT RULE
OUT AN ISOLATED STORM ANYWHERE ACROSS THE REGION. HOWEVER IT
APPEARS THAT THE KERI AREA MAY HAVE THE BEST CHANCE BUT STILL
NOTHING HIGHER THAN 30 PERCENT.
.OUTLOOK...NON-VFR CONDITIONS POSSIBLE IN CONVECTION THURSDAY
EVENING AND AGAIN FRIDAY AFTERNOON/EVENING. NON-VFR POSSIBLE ON
MONDAY.
&&
.MARINE...
WARM FRONT WILL BE IN THE VICINITY OF THE NORTH SHORE OF LAKE ERIE
TODAY. THIS SHOULD ALLOW FOR A SOUTH TO SOUTHWEST WIND ACROSS THE
ENTIRE LAKE. THE STRONGEST WINDS WILL LIKELY BE ACROSS THE WESTERN
BASIN BUT SHOULD NOT EXCEED 20 KNOTS. SOUTHWESTERLY WINDS WILL
CONTINUE INTO FRIDAY NIGHT WITH A WIND SHIFT EXPECTED BY SATURDAY
MORNING AS A COLD FRONT PASSES. HIGH PRESSURE IN THE WAKE OF THE
FRONT WILL REMAIN IN CONTROL INTO SUNDAY WITH NORTHEAST TO EAST
WINDS EXPECTED. THIS WILL LIKELY CAUSE WAVES TO BUILD BUT WITH WINDS
NOT EXPECTED TO BE HIGHER THAN 15 KNOTS WE SHOULD SEE 2 TO 4 FOOT
WAVES. WE WILL HAVE TO WATCH THE WESTERN HALF OF THE LAKE CLOSELY IF
WIND SPEEDS ARE A BIT STRONGER THAN ANTICIPATED. AS LOW PRESSURE
APPROACHES THE CENTRAL LAKES ON MONDAY WINDS SHOULD GRADUALLY SWING
AROUND TO THE SOUTH.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...ADAMS/TK
SHORT TERM...ADAMS
LONG TERM...MULLEN
AVIATION...MULLEN
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
939 AM CDT THU MAY 3 2012
.UPDATE...UPDATED ZONE PACKAGE TO FRESHEN IT UP A BIT. NO REAL
SUBSTANTATIVE CHANGES...MOST LOOKS ON TRACK. MODELS INDICATE THAT
THE UPPER LOW OVER WEST TN WILL MOVE A BIT FURTHER NORTH AND THEN
BE PUSHED EWD INTO EAST TN/KY BY THIS EVENING. AREA OF SCATTERED
TO NUMEROUS SHOWERS SHOULD MOVE INTO THE DAVIDSON COUNTY AREA SHORTLY
BUT PROBABLY START TO FRAGMENT A BIT AS DAYTIME HEATING TAKES
HOLD. LIGHTNING DATA HAS NO STRIKES IN THE AREA CURRENTLY...BUT
SOME TSTM DEVELOPMENT IS POSSIBLE...MAINLY TO THE EAST OF THE
CURRENT RAIN AREA. HI TEMPS IN THE LOWER 80S STILL LOOK FINE.
&&
.PREV DISCUSSION... /ISSUED 750 AM CDT THU MAY 3 2012/
UPDATE...
LATEST RADAR IMAGERY SHOWS LARGE AREA OF LIGHT TO MODERATE RAIN
SPREADING ACROSS SOUTHWEST MIDDLE TENNESSEE THIS MORNING.
CIRCULATION ASSOCIATED WITH UPPER LEVEL LOW APPEARS TO BE MOVING
MORE NORTHWARD THAN EARLIER MODEL RUNS INDICATED...MORE IN LINE
WITH 06Z GFS AND LOCAL WRF MODEL. THIS SHOULD HELP SPREAD
SOME BENEFICIAL RAIN ACROSS MUCH OF THE MID STATE TODAY.
ADDITIONAL SHOWERS AND THUNDERSTORMS SHOULD ALSO DEVELOP THIS
MORNING WITHIN AND TO THE EAST OF THE MAIN RAIN SHIELD WITH
ADDITIONAL DAYTIME HEATING. HAVE ADJUSTED POPS UPWARD ACROSS THE
BOARD AND RAISED TO CATEGORICAL ACROSS SOUTHERN COUNTIES ALONG THE
ALABAMA BORDER WHERE RAIN SHOULD CONTINUE THROUGH MUCH OF THE
MORNING HOURS AT LEAST. MADE OTHER MINOR ADJUSTMENTS TO GRIDS AND
ZONES AS WELL WITH UPDATED PRODUCTS OUT SHORTLY.
PREV DISCUSSION... /ISSUED 633 AM CDT THU MAY 3 2012/
UPDATE...FOR 12Z AVIATION FORECAST
AVIATION...
MESOCONVECTIVE VORTICITY FEATURE PUNCHING NORTHWARD THROUGH NORTHERN
ALABAMA AT 11Z WITH RAIN FIELD BEGINNING TO CURL MORE TOWARD THE
WEST AS IT HEADS NORTHWARD INTO SOUTHERN MIDDLE TENNESSEE. MODELS
DIFFER ON WHAT HAPPENS WITH RAIN AREA TODAY IN MID STATE. LATEST
RADAR LOOP MORE IN LINE WITH LATEST RUC RUN AND H-TRIPLE-R 08Z RUN
WHICH HAS THE RAIN REACHING NASHVILLE TERMINAL AROUND 16Z AND THEN
SPREADS EASTWARD ONTO PLATEAU AROUND 18Z. AS THE RAIN MOVED OVER
NORTH ALABAMA HUNTSVILLE MEASURED A TOTAL OF 0.05 INCH WITH VSBYS
NEVER GOING < P6SM AND CEILINGS REMAINING VFR...WITH SIMILAR
CONDITIONS AT MUSCLE SHOALS. MY GUT FEELING IS THAT THE RAIN AREA WILL
BECOME MORE WEST TO EAST ORIENTED RATHER THAN NORTH TO SOUTH AS
MODELS WANT TO DEPICT AND THEN SHIFT EASTWARD WHILE KEEPING AREAS
NORTH OF INTERSTATE 40 BASICALLY RAIN-FREE. ALL IN ALL NOT MUCH
CONFIDENCE IN FORECAST SO AVIATORS SHOULD LOOK FOR UPDATES AS WE
GO THROUGH THE MORNING.
BOYD
PREV DISCUSSION... /ISSUED 320 AM CDT THU MAY 3 2012/
DISCUSSION...
WATER VAPOR IMAGERY SHOWS A WEAK UPPER LEVEL LOW OVER MISSISSIPPI
THIS MORNING WITH A DEEP FEED OF TROPICAL MOISTURE SPREADING
NORTHWARD AHEAD OF THE LOW FROM THE GULF OF MEXICO THROUGH ALABAMA
INTO SOUTHERN MIDDLE TENNESSEE. THIS FEATURE WILL MOVE ACROSS THE
MID STATE TODAY...AND THE DEEPER MOISTURE COMBINED WITH THE LIFT
FROM THE UPPER LOW SHOULD PRODUCE SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS ACROSS THE MID STATE. HIGHEST RAIN CHANCES WILL
BE ACROSS SOUTHERN ZONES AND THE PLATEAU...AND RADAR IMAGERY
ALREADY SHOWS LIGHT RAIN INCREASING ACROSS NORTHERN ALABAMA THIS
MORNING AND MOVING NORTHWARD INTO WAYNE/LAWRENCE/GILES COUNTIES.
COULD ALSO SEE A FEW STRONG STORMS TODAY AS MODERATE INSTABILITY
DEVELOPS AND 925-500MB SOUTHERLY WIND FIELDS INTENSIFY UP TO 40
KNOTS...WITH STRONG WIND GUSTS THE MAIN THREAT. DUE TO THE
EXPECTED PRECIPITATION AND CLOUD COVER...HIGH TEMPERATURES WILL
BE QUITE A BIT COOLER THAN THE RECORD/NEAR RECORD HIGHS SEEN
YESTERDAY.
UPPER LEVEL LOW WILL MOVE OUT OF THE MID STATE OVERNIGHT WITH
NORTHWEST FLOW DEVELOPING ALOFT FROM FRIDAY INTO THE WEEKEND.
GUIDANCE INDICATES A WEAK SHORTWAVE WILL MOVE ACROSS THE CWA ON
FRIDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING BY
AFTERNOON AND CONTINUING THROUGH FRIDAY NIGHT. BULK SHEAR VALUES
INCREASING UP TO 40 KNOTS AND MODERATE INSTABILITY MAY LEAD TO A
FEW STRONG OR SEVERE THUNDERSTORMS...AND SPC HAS PLACED NORTHERN
PARTS OF THE MID STATE IN A SLIGHT RISK FOR SEVERE STORMS FOR
FRIDAY/FRIDAY NIGHT. AT LEAST LOW PRECIP CHANCES TO REMAIN IN THE
FORECAST THROUGH THE REMAINDER OF THE FORECAST PERIOD AS NORTHWEST
FLOW CONTINUES AND HEIGHTS GRADUALLY FALL INTO EARLY NEXT
WEEK...WITH TEMPERATURES SLOWLY COOLING DOWN CLOSER TO NORMAL
LEVELS.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
18
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
750 AM CDT THU MAY 3 2012
.UPDATE...
LATEST RADAR IMAGERY SHOWS LARGE AREA OF LIGHT TO MODERATE RAIN
SPREADING ACROSS SOUTHWEST MIDDLE TENNESSEE THIS MORNING.
CIRCULATION ASSOCIATED WITH UPPER LEVEL LOW APPEARS TO BE MOVING
MORE NORTHWARD THAN EARLIER MODEL RUNS INDICATED...MORE IN LINE
WITH 06Z GFS AND LOCAL WRF MODEL. THIS SHOULD HELP SPREAD
SOME BENEFICIAL RAIN ACROSS MUCH OF THE MID STATE TODAY.
ADDITIONAL SHOWERS AND THUNDERSTORMS SHOULD ALSO DEVELOP THIS
MORNING WITHIN AND TO THE EAST OF THE MAIN RAIN SHIELD WITH
ADDITIONAL DAYTIME HEATING. HAVE ADJUSTED POPS UPWARD ACROSS THE
BOARD AND RAISED TO CATEGORICAL ACROSS SOUTHERN COUNTIES ALONG THE
ALABAMA BORDER WHERE RAIN SHOULD CONTINUE THROUGH MUCH OF THE
MORNING HOURS AT LEAST. MADE OTHER MINOR ADJUSTMENTS TO GRIDS AND
ZONES AS WELL WITH UPDATED PRODUCTS OUT SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 633 AM CDT THU MAY 3 2012/
UPDATE...FOR 12Z AVIATION FORECAST
AVIATION...
MESOCONVECTIVE VORTICITY FEATURE PUNCHING NORTHWARD THROUGH NORTHERN
ALABAMA AT 11Z WITH RAIN FIELD BEGINNING TO CURL MORE TOWARD THE
WEST AS IT HEADS NORTHWARD INTO SOUTHERN MIDDLE TENNESSEE. MODELS
DIFFER ON WHAT HAPPENS WITH RAIN AREA TODAY IN MID STATE. LATEST
RADAR LOOP MORE IN LINE WITH LATEST RUC RUN AND H-TRIPLE-R 08Z RUN
WHICH HAS THE RAIN REACHING NASHVILLE TERMINAL AROUND 16Z AND THEN
SPREADS EASTWARD ONTO PLATEAU AROUND 18Z. AS THE RAIN MOVED OVER
NORTH ALABAMA HUNTSVILLE MEASURED A TOTAL OF 0.05 INCH WITH VSBYS
NEVER GOING < P6SM AND CEILINGS REMAINING VFR...WITH SIMILAR
CONDITIONS AT MUSCLE SHOALS. MY GUT FEELING IS THAT THE RAIN AREA WILL
BECOME MORE WEST TO EAST ORIENTED RATHER THAN NORTH TO SOUTH AS
MODELS WANT TO DEPICT AND THEN SHIFT EASTWARD WHILE KEEPING AREAS
NORTH OF INTERSTATE 40 BASICALLY RAIN-FREE. ALL IN ALL NOT MUCH
CONFIDENCE IN FORECAST SO AVIATORS SHOULD LOOK FOR UPDATES AS WE
GO THROUGH THE MORNING.
BOYD
PREV DISCUSSION... /ISSUED 320 AM CDT THU MAY 3 2012/
DISCUSSION...
WATER VAPOR IMAGERY SHOWS A WEAK UPPER LEVEL LOW OVER MISSISSIPPI
THIS MORNING WITH A DEEP FEED OF TROPICAL MOISTURE SPREADING
NORTHWARD AHEAD OF THE LOW FROM THE GULF OF MEXICO THROUGH ALABAMA
INTO SOUTHERN MIDDLE TENNESSEE. THIS FEATURE WILL MOVE ACROSS THE
MID STATE TODAY...AND THE DEEPER MOISTURE COMBINED WITH THE LIFT
FROM THE UPPER LOW SHOULD PRODUCE SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS ACROSS THE MID STATE. HIGHEST RAIN CHANCES WILL
BE ACROSS SOUTHERN ZONES AND THE PLATEAU...AND RADAR IMAGERY
ALREADY SHOWS LIGHT RAIN INCREASING ACROSS NORTHERN ALABAMA THIS
MORNING AND MOVING NORTHWARD INTO WAYNE/LAWRENCE/GILES COUNTIES.
COULD ALSO SEE A FEW STRONG STORMS TODAY AS MODERATE INSTABILITY
DEVELOPS AND 925-500MB SOUTHERLY WIND FIELDS INTENSIFY UP TO 40
KNOTS...WITH STRONG WIND GUSTS THE MAIN THREAT. DUE TO THE
EXPECTED PRECIPITATION AND CLOUD COVER...HIGH TEMPERATURES WILL
BE QUITE A BIT COOLER THAN THE RECORD/NEAR RECORD HIGHS SEEN
YESTERDAY.
UPPER LEVEL LOW WILL MOVE OUT OF THE MID STATE OVERNIGHT WITH
NORTHWEST FLOW DEVELOPING ALOFT FROM FRIDAY INTO THE WEEKEND.
GUIDANCE INDICATES A WEAK SHORTWAVE WILL MOVE ACROSS THE CWA ON
FRIDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING BY
AFTERNOON AND CONTINUING THROUGH FRIDAY NIGHT. BULK SHEAR VALUES
INCREASING UP TO 40 KNOTS AND MODERATE INSTABILITY MAY LEAD TO A
FEW STRONG OR SEVERE THUNDERSTORMS...AND SPC HAS PLACED NORTHERN
PARTS OF THE MID STATE IN A SLIGHT RISK FOR SEVERE STORMS FOR
FRIDAY/FRIDAY NIGHT. AT LEAST LOW PRECIP CHANCES TO REMAIN IN THE
FORECAST THROUGH THE REMAINDER OF THE FORECAST PERIOD AS NORTHWEST
FLOW CONTINUES AND HEIGHTS GRADUALLY FALL INTO EARLY NEXT
WEEK...WITH TEMPERATURES SLOWLY COOLING DOWN CLOSER TO NORMAL
LEVELS.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
633 AM CDT THU MAY 3 2012
.UPDATE...FOR 12Z AVIATION FORECASST
&&
.AVIATION...
MESOCONVECTIVE VORTICITY FEATURE PUNCHING NORTHWARD THROUGH NORTHERN
ALABAMA AT 11Z WITH RAIN FIELD BEGINNING TO CURL MORE TOWARD THE
WEST AS IT HEADS NORTHWARD INTO SOUTHERN MIDDLE TENNESSEE. MODELS
DIFFER ON WHAT HAPPENS WITH RAIN AREA TODAY IN MID STATE. LATEST
RADAR LOOP MORE IN LINE WITH LATEST RUC RUN AND H-TRIPLE-R 08Z RUN
WHICH HAS THE RAIN REACHING NASHVILLE TERMINAL AROUND 16Z AND THEN
SPREADS EASTWARD ONTO PLATEAU AROUND 18Z. AS THE RAIN MOVED OVER
NORTH ALABAMA HUNTSVILLE MEASURED A TOTAL OF 0.05 INCH WITH VSBYS
NEVER GOING < P6SM AND CEILINGS REMAINING VFR...WITH SIMILAR
CONDITIONS AT MUSCLE SHOALS. MY GUT FEELING IS THAT THE RAIN AREA WILL
BECOME MORE WEST TO EAST ORIENTED RATHER THAN NORTH TO SOUTH AS
MODELS WANT TO DEPICT AND THEN SHIFT EASTWARD WHILE KEEPING AREAS
NORTH OF INTERSTATE 40 BASICALLY RAIN-FREE. ALL IN ALL NOT MUCH
CONFIDENCE IN FORECAST SO AVIATORS SHOULD LOOK FOR UPDATES AS WE
GO THROUGH THE MORNING.
BOYD
&&
.PREV DISCUSSION... /ISSUED 320 AM CDT THU MAY 3 2012/
DISCUSSION...
WATER VAPOR IMAGERY SHOWS A WEAK UPPER LEVEL LOW OVER MISSISSIPPI
THIS MORNING WITH A DEEP FEED OF TROPICAL MOISTURE SPREADING
NORTHWARD AHEAD OF THE LOW FROM THE GULF OF MEXICO THROUGH ALABAMA
INTO SOUTHERN MIDDLE TENNESSEE. THIS FEATURE WILL MOVE ACROSS THE
MID STATE TODAY...AND THE DEEPER MOISTURE COMBINED WITH THE LIFT
FROM THE UPPER LOW SHOULD PRODUCE SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS ACROSS THE MID STATE. HIGHEST RAIN CHANCES WILL
BE ACROSS SOUTHERN ZONES AND THE PLATEAU...AND RADAR IMAGERY
ALREADY SHOWS LIGHT RAIN INCREASING ACROSS NORTHERN ALABAMA THIS
MORNING AND MOVING NORTHWARD INTO WAYNE/LAWRENCE/GILES COUNTIES.
COULD ALSO SEE A FEW STRONG STORMS TODAY AS MODERATE INSTABILITY
DEVELOPS AND 925-500MB SOUTHERLY WIND FIELDS INTENSIFY UP TO 40
KNOTS...WITH STRONG WIND GUSTS THE MAIN THREAT. DUE TO THE
EXPECTED PRECIPITATION AND CLOUD COVER...HIGH TEMPERATURES WILL
BE QUITE A BIT COOLER THAN THE RECORD/NEAR RECORD HIGHS SEEN
YESTERDAY.
UPPER LEVEL LOW WILL MOVE OUT OF THE MID STATE OVERNIGHT WITH
NORTHWEST FLOW DEVELOPING ALOFT FROM FRIDAY INTO THE WEEKEND.
GUIDANCE INDICATES A WEAK SHORTWAVE WILL MOVE ACROSS THE CWA ON
FRIDAY...WITH SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING BY
AFTERNOON AND CONTINUING THROUGH FRIDAY NIGHT. BULK SHEAR VALUES
INCREASING UP TO 40 KNOTS AND MODERATE INSTABILITY MAY LEAD TO A
FEW STRONG OR SEVERE THUNDERSTORMS...AND SPC HAS PLACED NORTHERN
PARTS OF THE MID STATE IN A SLIGHT RISK FOR SEVERE STORMS FOR
FRIDAY/FRIDAY NIGHT. AT LEAST LOW PRECIP CHANCES TO REMAIN IN THE
FORECAST THROUGH THE REMAINDER OF THE FORECAST PERIOD AS NORTHWEST
FLOW CONTINUES AND HEIGHTS GRADUALLY FALL INTO EARLY NEXT
WEEK...WITH TEMPERATURES SLOWLY COOLING DOWN CLOSER TO NORMAL
LEVELS.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1034 AM CDT THU MAY 3 2012
.UPDATE...LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A
BROAD AREA OF LOW PRESSURE CENTERED OVER SOUTHERN MINNESOTA AND
NORTHERN IOWA...WITH A WARM FRONT EXTENDING ACROSS CENTRAL
WISCONSIN TO AROUND MANITOWOC. AN MCV IS TRACKING ALONG THE WARM
FRONT OVER CENTRAL WISCONSIN...WHICH HAS IGNITED ANOTHER ROUND OF
SHOWERS AND THUNDERSTORMS. WITH CLOUD TOPS COOLING...POTENTIAL
WILL REMAIN FOR AN ISOLATED SEVERE WEATHER THREAT UNTIL ABOUT
MIDDAY...WHEN THE MCV DEPARTS. HAVE HAD WIND GUSTS UP TO 40 KTS
AND NICKEL SIZED HAIL WITH THE STORMS PROGRESSING ACROSS EAST-
CENTRAL WISCONSIN SO FAR.
WITH THE WARM FRONT EXTENDING BACK TOWARDS MINNEAPOLIS WHERE
ANOTHER NEAR SEVERE CLUSTER OF STORMS EXISTS...POTENTIAL WILL BE
THERE FOR SCATTERED THUNDERSTORM ACTIVITY THROUGH THE AFTERNOON.
THOUGH DID PLACE THE HIGHEST POPS OVER NE WISCONSIN WITHIN THE
COMMA HEAD OF THE MCV THAT WILL BE DEPARTING EARLY THIS AFTERNOON.
AS FOR THE SEVERE THREAT...THE ATMOSPHERE HAS BEEN WORKED OVER
CONTINUOUSLY SINCE THE OVERNIGHT HOURS...AND WILL NEED TO SEE SOME
HEATING IN ORDER TO GET A SURFACE BASED THREAT. CONFIDENCE IS LOW
THAT THIS WILL OCCUR...DO TO THE ONGOING CONVECTION...AND CLOUD
COVER UPSTREAM. WOULD THINK OUTFLOW BOUNDARIES SOUTH OF THE
CONVECTION OVER SOUTHERN WISCONSIN WOULD STAND A BETTER CHANCE.
WILL KEEP AN EYE ON IT...AND WILL SEE IF THE CLUSTER NEAR MSP CAN
STAY ALIVE INTO CENTRAL WISCONSIN LATER THIS AFTERNOON.
MPC
&&
.PREV DISCUSSION...ISSUED AT 339 AM CDT THU MAY 3 2012...
SYNOPSIS...WARM AND HUMID WITH SHOWERS AND THUNDERSTORMS
TODAY...THEN TURNING COOLER AND LESS HUMID.
BROAD UPR TROF PRESENTLY COVERS THE WRN 3/4 OF THE CONUS...WITH
RIDGING OVER THE FAR E. DEVELOPING BLOCKING PATTERN OVER FAR ERN
CANADA AND THE NW ATL WL FORCE ERN CONUS RIDGE TO REFORM WEST OVER
THE GREAT LAKES RGN DURING THE WEEKEND...THEN THE REMNANTS OF THE
WRN TROF WL PROGRESS EWD ACRS THE RGN DURING THE EARLY TO MIDDLE
PART OF NEXT WK.
HAVING THE UPR PATTERN IN A STATE OF FLUX WL RESULT IN A VARIETY
OF WX ACRS THE FCST AREA. WARM AND WET PATTERN WL PREVAIL EARLY...
WITH FLOODING NOW ONGOING ACRS THE FAR SRN PART OF THE FCST AREA.
A SWD SURGE OF COOLER CANADIAN AIR WL PUSH THE BULK OF THE PCPN S
AND ALLOW COOLER AIR TO DOMINATE FOR A DAY OR TWO. THEN CHCS FOR
PCPN WL RETURN AS REMNANTS OF THE WRN TROF HEAD TOWARD THE AREA.
PCPN AMNTS FOR THE 7 DAY PERIOD SHOULD END UP ABV NORMAL.
TEMPS WL START OUT ABV NORMAL THEN FALL BACK CLOSER TO NORMAL.
SHORT TERM...TDA/TNGT/FRI. MAIN CONCERN IS ONGOING FLASH
FLOODING ACRS THE FAR SRN PART OF THE FCST AREA. LINE OF
CONVECTION PRODUCING THE FLOODING WAS BEING FED BY SWLY LLJ OF
40-45 KTS... WHICH WAS FEEDING INSTABILITY IN FM THE SW. MESO
PLOTS THE LAST COUPLE HRS SHOWED THE STRONGEST LOW-LEVEL MOISTURE
CONVERGENCE STARTING TO SHIFT OFF TO THE E IN RESPONSE TO GRADUAL
VEERING OF THE LLJ. SO THINK THE AMNT OF BACKBUILDING AND TRAINING
INTO THE FLOOD ZONE WL DECR. SCHEDULED 10Z/11Z EXPIRATION TIMES OF
THE WARNINGS MIGHT BE CUTTING IT CLOSE...ESP SINCE FLOODING WL
LINGER EVEN AFTER RAIN DIMINISHES. WL NEED TO RE-EVALUATE THAT AS
WE GET CLOSE TO THE EXPIRATION TIMES.
PCPN TRENDS LATER TDA NOT VERY CLEAR CUT. GIVEN MID-LVL SHRTWV
HEADED INTO THE AREA...POSN OF FCST AREA NR RRQ OF UPR JET...AND
COLD FRONT SET TO SAG INTO THE N THIS AFTN...ADDITIONAL TSRA
DEVELOPMENT SEEMS A GOOD BET. BUT SUSPECT IT WON/T BE QUITE AS
FOCUSED/ORGAINZED AS CURRENT BATCH. WL CARRY FAIRLY HIGH
POPS...BUT DON/T FEEL MUCH IN THE WAY OF SPECIFICS/DETAILS CAN BE
ADDED AT THIS POINT. SPC SLGT RISK COVERS ABOUT THE SRN 1/2 OF THE
FCST AREA. ALTHOUGH A SVR STORM CAN/T BE RULED OUT...RIGHT NOW
THERE WOULD SEEM TO BE TOO MANY CLDS AND NOT ENOUGH FOCUSED
FORCING FOR MORE THAN A MARGINAL SVR EVENT.
FRONT WL CONT TO SAG SWD TNGT. SLOWLY EDGED POPS SWD DURING THE
NIGHT...DRYING OUT THE N AFTER MIDNIGHT. LINGERED LOW POPS OVER
THE FAR S EARLY FRI...AND BROUGHT LOW POPS BACK INTO THE FAR NW
LATE IN THE DAY. ADJUSTED TEMPS DOWN AS INCRG NELY FLOW WILL BRING
COOLER AND DRIER AIR INTO THE RGN...AND ACRS THE COLD WATERS OF
THE GREAT LAKES.
LONG TERM...FRI NGT THRU NXT WED. MAIN FCST FOCUS TO BE THE
MOVEMENT OF AN EWD MOVING...POSITIVELY-TILTED UPR TROF WHICH
EVENTUALLY SPLITS INTO A SW CONUS CUT-OFF UPR LOW AND NEARLY
CUT-OFF UPR LOW OVER THE GREAT LKS. INITIALLY...STILL DEALING
WITH ACTIVE W-SW FLOW THRU THE WEEKEND WITH SMALL PCPN CHCS AND
THEN INSTABILITY PCPN TOWARD MID-WEEK WITH THE UPR LOW. TEMPS ARE
EXPECTED TO AVERAGE BLO NORMAL THRU THE MIDDLE OF NXT WEEK.
MDLS ARE STILL AT ODDS WITH THE TIMING OF THE NXT PROMINENT
SHORTWAVE TOPPING THE RELATIVELY FLAT UPR RDG SITUATED OVER THE
CNTRL CONUS. LATEST THINKING IS FOR BETTER PCPN CHCS TO ARRIVE
LATER FRI NGT (AFTER MIDNGT) AND FOCUSED MORE TOWARD CNTRL WI.
HAVE ADDED MORE CLOUDS TOWARD CNTRL WI AND KEPT POPS IN THE CHC
CATEGORY. FARTHER EAST...ENUF DRY AIR MAY KEEP MOST OF THE PCPN AT
BAY FOR MOST OF THE NGT SO HAVE KEPT POPS THERE AT A MINIMUM.
THIS SHORTWAVE PULLS AWAY FROM THE AREA BY SAT MORNING LEAVING AN
EASTERLY FLOW OVER NE WI AND WAITING FOR THE NXT SHORTWAVE TO
APPROACH. IT APPEARS THAT THERE IS A GAP LARGE ENUF SUCH THAT ANY
PCPN CHCS COULD HOLD OFF TIL AFTER SUNSET. SINCE THERE IS NO
TRIGGER EVIDENT AT THE SFC OR ALOFT...MAY BE ABLE TO GET BY MOST
OF THE DAY WITHOUT SEEING MEASURABLE PCPN. STILL EXPECT TO SEE
ENUF CLOUDS AROUND TO KEEP TEMPS IN CHECK WITH READINGS RANGING
FROM THE UPPER 50S LAKESIDE TO THE MIDDLE 60S OVER THE WARMER
SPOTS OF CNTRL WI.
HI PRES DROPPING SE INTO ERN ONTARIO WL CONT TO FUNNEL DRY AIR
INTO NE WI SAT NGT WHILE THE NEARLY CLOSED UPR LOW MOVES TOWARD
ND/SRN MANITOBA. THE NXT SHORTWAVE IS FCST TO RIDE INTO THE UPR MS
VALLEY...BUT AGAIN MDLS DISAGREE ON ITS LOCATION. THIS BRINGS A
SIGNIFICANT TIMING ISSUE TO WHEN TO BRING THE NXT CHC OF SHWRS/
TSTMS TO THE FCST AREA. ONCE AGAIN...IT WOULD SEEM CNTRL WI WOULD
HAVE THE BETTER CHC OF SEEING MEASURABLE PCPN AS THE EAST IS
SOMEWHAT PROTECTED BY THE DRY EASTERLY WINDS. THE HI PRES BEGINS
TO LOSE ITS INFLUENCE OVER ERN WI ON SUNDAY AS THE NEARLY
VERTICALLY STACKED LOW PRES SYSTEM SPINS OVER SRN MANITOBA.
SOMEWHAT OF A BLOCKING PATTERN ALOFT WL SLOW THE ADVANCEMENT OF
BOTH THE SHORTWAVE ALOFT...AS WELL AS A CDFNT THRU THE UPR MS
VALLEY. THEREFORE...WL NEED TO CARRY A HIGHER CHC POP ACROSS CNTRL
WI (CLOSER TO THE SHORTWAVE/CDFNT) WITH ENUF INSTABILITY TO
GENERATE ISOLATED TSTMS. IT IS CONCEIVABLE THAT FAR ERN WI MAY
REMAIN MOSTLY DRY THRU SUNDAY.
THE CDFNT IS PROGGED TO PUSH ACROSS WI SUNDAY NGT AND BRING A GOOD
CHC OF SHWRS/TSTMS TO ALL OF NE WI. COOLER AIR WL SWEEP ACROSS THE
STATE BEHIND THE FNT WITH 8H TEMPS DROPPING INTO THE SINGLE DIGITS
BY MIDDAY MON. MEANWHILE...THE AREA OF LOW PRES SOUTH OF LK
WINNIPEG MAY EASE ITS WAY EWD INTO SW ONTARIO. SOME SHWR ACTIVITY
MAY LINGER INTO MON MORNING PRIMARILY OVER THE EAST...HOWEVER A
DRYING TREND DOES SEEM TO BE AGREED UPON BY THE MDLS FORO THE REST
OF MON. TEMPS WL DROP TO BLO NORMAL LEVELS WITH MAX TEMPS ON MON IN
THE UPR 50S TO LWR 60S.
MDLS EVENTUALLY BRING THIS WEAKENING LOW PRES SYSTEM (SHORTWAVE
TROF ALOFT/WEAK SFC LOW) TOWARD/INTO THE GREAT LKS REGION NXT TUE
AND WED. DAYTIME HEATING COUPLED WITH A COLD POOL ALOFT WL
INCREASE INSTABILITY TO BRING A CHC OF SHWRS/TSTMS TO NE WI
PRIMARILY DURING THE AFTERNOON HOURS.
&&
.AVIATION...FOR 12Z TAF ISSUANCE...TSRA WL PROBABLY WORK BACK INTO
THE WRN AND NRN TAF SITES...AND KEY WL BE TO HONE IN ON TIMING OF
THAT. KEY TO TNGT WL BE FIGURING OUT POTENTIAL FOR LOW CIGS RIGHT
BEHIND THE FRONT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DENVER CO
334 PM MDT THU MAY 3 2012
.SHORT TERM...CUMULUS CONTINUES TO DEVELOP ACROSS MOUNTAINS AND
FOOTHILLS AS WELL AS PORTIONS OF URBAN CORRIDOR. BATCH OF PASSING
CIRRUS SEEMS TO HAVE HALTED FURTHER DEVELOPMENT. RECENT RADAR
LOOPS FINALLY A CELL OVER WEST CENTRAL BOULDER COUNTY. OTHER CELLS
SHOWING UP OVER BOULDER AND SOUTHWEST LARIMER COUNTIES IN THE 1.5
DEGREE SCAN. CURRENT LAPS SURFACE ANALYSIS SHOWING CAPES FROM
100-300 J/KG OVER THE HIGH COUNTRY AS WELL AS IN AND NEAR
FOOTHILLS...LESS FURTHER EAST. STILL CANNOT RULE OUT ADDITIONAL STORMS
DEVELOPING ACROSS THE AREA BY THIS EVENING. THIS THINKING IN LINE
WITH LATEST HRR AND RUC WHICH SHOW AREA OF CONVECTION MOVING
QUICKLY ACROSS PLAINS DURING THE EVENING...AND LOOKS REASONABLE.
ACARS SOUNDINGS STILL INDICATING AIRMASS A BIT CAPPED...AND FOR
THIS REASON WILL NOT INCREASE POPS. FORECAST SOUNDINGS SHOW
INVERTED-V TYPE SOUNDINGS SO ANY CONVECTION THAT DEVELOPS WILL
PRODUCE MORE WIND THAN RAIN. LATEST NAM STILL MORE UNSTABLE THAT
THE OTHER MODELS DUE TO HIGHER DEWPOINTS AND THUS INDICATING MORE
PRECIP. SEEMS A BIT OVERDONE. DRIER SUBSIDENT AIR TO MOVE ACROSS
AREA FROM WEST TO EAST THIS EVENING... SO ANY LINGERING STORMS
OVER FAR NORTHEAST CORNER SHOULD DONE BY MIDNIGHT...WITH SKIES
CLEARING OVERNIGHT. REMOVED ANY MENTION OF FOG FAR NORTHEAST
CORNER LATE TONIGHT AND EARLY FRIDAY BOUNDARY LAYER WIND AND
HUMIDITY PROGS SHOW ANY LINGERING LOW LEVEL MOISTURE EAST OF AREA.
ON FRIDAY A DRIER SOUTHWEST FLOW ALOFT WILL BE OVER AREA WITH
AFTERNOON HUMIDITY REMAINING LOW. WINDS ALOFT NOT ALL THAT STRONG
SO SURFACE WINDS SHOULD REMAIN FAIRLY LIGHT DESPITE ANY MIXING.
NO FIRE WEATHER CONCERNS EXPECTED. TEMPERATURES TO BE A FEW
DEGREES WARMER DUE TO A SLIGHTLY WARMER AIRMASS.
.LONG TERM...A MAINLY DRY SOUTHWESTERLY FLOW ALOFT WILL BE OVER
THE CWFA FOR FRIDAY NIGHT AND SATURDAY WITH THE NEXT SYSTEM
MOVING INTO THE NORTHERN ROCKIES BY 00Z SUNDAY. IT WILL REMAIN
WARM AND DRY THROUGH THE DAY SO THE FIRE DANGER WILL REMAIN
ELEVATED BUT THE WINDS STILL LOOK FAIRLY WEAK DURING THE DAY. THE
STRONGEST WINDS THAT DEVELOP ARE NOT EXPECTED TO OCCUR UNTIL THE
PASSAGE OF A COLD FRONT SATURDAY EVENING. MID AND UPPER LEVEL
MOISTURE WILL INCREASE FM THE NORTH AND WEST SATURDAY NIGHT WITH A
COLD FRONT PROGGED TO PUSH THROUGH THE CWFA AT THAT TIME. AS A
RESULT...THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND TSTMS
OVERNIGHT. FOR SUNDAY...A MUCH COOLER AMS WILL BE IN PLACE OVER
THE NORTHEAST PLAINS AS SURFACE HIGH PRESSURE WILL BE FIRMLY IN
CONTROL. TEMPERATURES WILL BE 15-20 DEGREES COOLER THAN SATURDAY.
THE NAM12 FORECAST SOUNDINGS INDICATE A MUCH STRONGER INVERSION
PRESENT AT 700 MB SUNDAY AFTN. THE GFS BUFFER SOUNDINGS STILL SHOW
AN INVERSION BUT NOT AS PRONOUNCED. AS A RESULT...THE BEST CHANCE
OF PCPN WILL LIKELY BE IN AND NEAR THE FRONT RANGE FOOTHILLS. BUT
AT THIS POINT IT LOOKS LIKE SHOWERS VS TSTMS WITH LIMITED
INSTABILITY PRESENT. BY 00Z MONDAY...THE NORTHERN BRANCH THE UPPER
TROUGH WILL BE OVER NORTH DAKOTA WITH THE SRN BRANCH CLOSING OFF
OVER THE CENTRAL CA COAST. SUNDAY NIGHT THE MDLS INDICATE SOME
WEAK MID LEVEL QG ASCENT MOVING ACROSS NORTHERN CO OVERNIGHT. AS A
RESULT...WL CONTINUE WITH CHC/SLGT CHC POPS AT THAT TIME. THE AMS
WILL REMAIN COOL AND UNSETTLED OVER NERN CO THROUGH THE DAY
MONDAY/MONDAY NIGHT. THE FLOW ALOFT APPEARS TO BE WEST/SWLY BUT WITH
LIMITED INSTBY PRESENT. FOR NOW WL CONTINUE WITH A CHC/SLGT CHC OF
SHOWERS/TSTMS. BY TUESDAY...A DRIER NORTHWESTERLY FLOW ALOFT WILL BE
OVER NORTHEASTERN CO. THE SECONDARY BRANCH OF THE TROUGH WILL BE
OVER BAJA CA BY 18Z TUESDAY. IF THIS TREND CONTINUES...THEN THE
CHC OF ANY RAINFALL WILL DECREASE SIGNIFICANTLY OR DIMINISH
ALTOGETHER FOR TUESDAY AND WEDNESDAY. THE TROUGH IS PROGGED TO
SHIFT EAST INTO WESTERN TX BY MIDDAY THURSDAY. IF ITS TRACK SHIFTS
FURTHER NORTH...THEN THE CHANCE OF PCPN WILL INCREASE FM SOUTH TO
NORTH ACROSS THE AREA. THE MDLS DO DIFFER IN TERMS OF THE TIMING
OF THE CLOSED LOW BUT UNFORTUNATELY MOST KEEP IT TOO FAR SOUTH TO
BRING ANY BENEFICIAL PCPN TO THE CWFA AT THIS POINT.
&&
.AVIATION...SOUTHEAST WINDS CONTINUE ACROSS AREA AIRPORTS WITH
SOME GUSTS TO 25 KTS...SHOULD CONTINUE THROUGH 02Z. SOME HIGH
BASED SHOWERS AND STORMS BEGINNING TO DEVELOP ACROSS FOOTHILLS.
STILL A SLIGHT CHANCE OF A HIGH BASED THUNDERSTORM THROUGH 02Z
WITH GUSTY OUFLOW WINDS TO 50 MPH POSSIBLE. WINDS TO WEAKEN AND
SHIFT TO THE SOUTHWEST BY 04Z AS DRAINAGE FLOW DEVELOPS...THEN
SHIFT TO THE NORTHWEST BY 18Z. VFR TO CONTINUE.
&&
.HYDROLOGY...SOME SHOWERS AND THUNDERSTORMS POSSIBLE THIS EVENING
WHICH WILL PRODUCE MORE WIND THAN RAIN. ACTIVITY TO MOVE FAIRLY
QUICKLY WHICH WILL LIMIT THE RAINFALL TO AROUND A TENTH OF AN
INCH. DRY CONDITIONS TO PREVAIL FRIDAY.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....D-L
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS DENVER CO
1020 AM MDT THU MAY 3 2012
.UPDATE...SOUTHEAST WINDS DOMINATING SURFACE PATTERN ACROSS PLAINS
AT PRESENT. ALL MODELS ARE CONSISTENT WITH INITIAL CONVECTIVE
DEVELOPING ALONG HIGHER TERRAIN...MAINLY FOOTHILLS AROUND 18Z.
THERE IS SOME HINT OF AN EAST-WEST ORIENTED BOUNDARY IN THE TDEN
VELOCITY DATA ACROSS THE DENVER AREA WHICH MAY PROVIDE A FOCUS FOR
ADDITIONAL STORM DEVELOPMENT. BOTH NAM AND HRRR PUSH A BOUNDARY
EAST OFF THE FOOTHILLS BY LATE AFTERNOON...SO NOT SURE IF THE
CURRENT BOUNDARY WILL BE A FACTOR. NAM IS STILL SHOWING MORE
AFTERNOON INSTABILITY THAT THE OTHER MODELS AND THUS GENERATING
MORE PRECIPITATION. STILL NOT A WELL DEFINED DISTURBANCE TO HELP
WITH CONVECTION...SO WILL MAINTAIN THE CURRENT POPS AND WEATHER.
SURFACE DEWPOINTS IN THE 30S MOST AREAS WITH SOME 40S FAR EASTERN
PLAINS. SO LOW LEVELS STILL A BIT DRY AND ANY SHOWERS OR STORMS
THAT DO DEVELOP WILL PRODUCE MORE WIND THAN RAIN.
&&
.AVIATION...CURRENT TAF TRENDS SEEM ON TRACK...THOUGH THE SOUTHEAST
WINDS A BIT GUSTY AT APA AND DEN AND WILL NEED TO INCREASE THE
SPEEDS A BIT. ISOLATED HIGH BASED STORMS STILL A POSSIBILITY OVER
THE DENVER AREA BETWEEN 21Z AND 01Z...WITH WITH BRIEF GUSTY
OUTFLOW WINDS OF 40-50 MPH.
&&
.PREV DISCUSSION... /ISSUED 346 AM MDT THU MAY 3 2012/
SHORT TERM...SW FLOW ALOFT WILL BE OVER THE AREA TODAY AND
TONIGHT. AT THIS TIME CAN NOT SEE ANY WELL DEFINED DISTURBANCE
EMBEDDED IN THIS FLOW TO ENHANCE CONVECTION THIS AFTN AND EVENING.
MEANWHILE AFTN INSTABILITY ACROSS NERN CO VARIES GREATLY BETWEEN
THE MODELS WITH THE NAM HAVE THE BEST INSTABILITY WHILE THE GFS
..ECMWF AND HI RES WRF ARE NOT AS UNSTABLE. AS A RESULT THE NAM
GENERATES FAR MORE CONVECTION THAN THE OTHER MODELS. AT THIS TIME
WILL KEEP TSTM COVERAGE IN THE WDLY SCT CATEGORY OVER NERN CO AND
OVER THE HIGHER TERRAIN. AS FOR HIGHS WILL KEEP READINGS MAINLY IN
THE UPPER 70S TO LOWER 80S ACROSS NERN CO. FOR TONIGHT ANY TSTM
ACTIVITY DURING THE EVENING HOURS SHOULD GRADUALLY END OVER THE
FAR NERN PLAINS BY MIDNIGHT.
LONG TERM...NO REAL CHANGES TO THE FORECAST PACKAGE THIS TIME
AROUND. FRIDAY AND SATURDAY WILL BE WARM AND DRY AS THE UPPER AIR
PATTERN OVER THE U.S. AMPLIFIES AND SOUTHWEST FLOW ALOFT INCREASES
OVER COLORADO. WARM AIR WILL ADVECT OVER THE STATE FROM THE DESERT
SOUTHWEST. CHANGES ARE IN STORE FOR SUNDAY AS A SURFACE COLD FRONT
DROPS INTO THE STATE SATURDAY NIGHT AND AN UPPER TROUGH PASSES
OVERHEAD. COOLER TEMPERATURES WILL RESULT ALONG WITH A MORE
UNSETTLED AIRMASS. THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
CONTINUE FROM SUNDAY THROUGH THE EARLY PART OF NEXT WEEK. UPPER
LEVEL TROUGHINESS WILL CONTINUE OVER THE GREAT BASIN AND CENTRAL
ROCKY MOUNTAIN REGIONS...BUT THE ECMWF...CANADIAN AND GFS MODELS
EACH HAVE DIFFERENT SOLUTIONS WHEN TRYING TO NAIL DOWN ANY
DETAILS. THIS WILL LEAVE US WITH NOTHING TO DO BUT HANG ON TO THE
CHANCE OF SHOWERS THROUGH NEXT WEDNESDAY. TEMPERATURES WILL BE
GRADUALLY MODERATING THROUGH THE EXTENDED PORTION OF THE FORECAST
AFTER THE COOLEST DAYS ON SUNDAY...MONDAY AND TUESDAY.
AVIATION...VFR THRU TONIGHT. ISOLATED HIGHER BASED THUNDERSTORMS
WILL BE POSSIBLE FM 21Z-01Z. THE STORMS MAY PRODUCE SOME BRIEF
GUSTY WINDS OF 40-50 MPH. WINDS WILL BE DRAINAGE THIS MORNING AND
THEN BECOME MORE SSE THIS AFTN. AFT 02Z THE WINDS SHOULD GRADUALLY
SHIFT BACK TO DRAINAGE.
HYDROLOGY...ISOLATED HIGHER BASED THUNDERSTORMS WILL BE POSSIBLE
THIS AFTERNOON. HOWEVER THE STORMS WILL MOVE RATHER QUICKLY WHICH
WILL LIMIT RAINFALL TO AROUND A TENTH OF AN INCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
550 PM CDT THU MAY 3 2012
.MESOSCALE DISCUSSION...
550 PM CDT
ISOLATED CONVECTIVE CELLS HAVE DEVELOPED FROM NEAR PEORIA
NORTHEAST TO LA SALLE COUNTY...ALONG WITH SOME ECHOES OVER
CHICAGO. THIS DEVELOPMENT ALIGNS WELL WITH LOW-LEVEL SPEED AND
MOISTURE CONVERGENCE. ALONG THIS RIBBON...A LOCALIZED POOL OF 67
TO 70 TDS EXIST...AND AN ASSOCIATED UNCAPPED MLCAPE AXIS OF 3000
TO 4000 J/KG PER MODIFIED RUC SOUNDINGS IN THE SOUTHWEST AND
CENTRAL FORECAST AREA. AMDAR SOUNDINGS TOWARD CHICAGO DO STILL
SHOW A MINOR CAP IN PLACE WHEN LIFTING FROM THE SURFACE...ALTHOUGH
PLENTY OF CAPE ABOVE IT. A MAXIMA OF PRESSURE FALLS OF 3 TO 6 MB
PER 3 HOURS WAS ANALYZED ACROSS THE ILLINOIS RIVER VALLEY AREA OF
CENTRAL IL...POSSIBLY ASSOCIATED WITH A WEAK RIPPLE TRACKING
NORTHEAST ALONG THE SURFACE BOUNDARY.
IF THE ANALYSIS OF CAPE/CIN IS CORRECT...THE CONVECTION SHOULD
FURTHER ENHANCE TO THE NORTHEAST WITH THE CONVERGENCE IN SUCH A
RICH POOL OF UNCAPPED INSTABILITY. FURTHER NORTH AND NORTHEAST
TOWARD CHICAGO...CUMULUS CONGESTUS IS TRYING TO DEVELOP AS
WELL...AND COULD SEE THINGS FILL IN BETWEEN THE ONGOING ECHOES.
THE HRRR AND RAP HAVE BEEN FORECASTING THIS ALL AFTERNOON...THOUGH
THEY HAVE ALREADY BEEN TOO ROBUST. DEEP LAYER SHEAR OF 30 TO 40 KT
WILL BE ENOUGH TO SUPPORT ORGANIZED UPDRAFTS AND OVERALL MORE
PERSISTENT STORMS THAN WHAT WE HAVE SEEN LOCALLY SO FAR. IF STORMS
DO GET DEVELOPING...THEY SHOULD BE ABLE TO FESTER AND CONTINUE NEW
GROWTH OFF OF OUTFLOWS DUE TO SUCH HIGH INSTABILITY. GIVEN THE
INSTABILITY WITH THE SHEAR...THERE CERTAINLY WILL BE PLENTY FOR
HAIL AND WIND POTENTIAL IF ANY STORMS PERSIST AWHILE. THE LOW-
LEVEL WIND FIELD HAS VEERED QUITE A BIT FROM AN HOUR OR TWO AGO IN
THE SOUTHWEST FORECAST AREA. LOW LCLS...SUFFICIENT LOW-LEVEL
CAPE...AND THE PRESENCE OF MULTIPLE BOUNDARIES PER SATELLITE
ANALYSIS MAY OFFSET THIS THOUGH AND CONTINUE TO PROVIDE SOME
TORNADO POTENTIAL. THIS IS ESPECIALLY TRUE IN AND AROUND THE
TORNADO WATCH AREA...WHERE 15 TO 20 KT 0-1KM SHEAR IS PRESENT.
MTF
&&
.DISCUSSION...
315 PM CDT
TONIGHT...
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE ONGOING
OVERNIGHT AND IT IS DIFFICULT TO ADD ANY SPECIFICS THIS AFTERNOON
AS TO WHEN THE HEAVIEST OF ACTIVITY WILL POP AND MOVE ACROSS...AS
GUIDANCE HAS BEEN STRUGGLING TO LATCH ONTO A SOLID SOLUTION. THE
HRRR AND RAP HAVE BEEN PRETTY CONSISTENT FROM RUN TO RUN IN
DEVELOPING CONVECTION ACROSS THE NORTHERN BORDER THIS AFTERNOON
AND EVENING...BUT AS THE MODELS HAVE BEEN UNDER PERFORMING THE LAST
FEW DAYS...NOT GOING TO COMPLETELY BITE OFF ON ANY ONE SOLUTION
HAPPENING THIS EVENING...LEADING TO A LOW CONFIDENCE OVERNIGHT
FORECAST. DO BELIEVE THAT THE ONGOING ACTIVITY FROM MKE TO ROUGHLY
MSN WILL TRY TO WORK SOUTH WHILE MOVING EAST...BUT WILL DEFER TO
SPECIFICS THAT FALL WITHIN THE MESO AFD ABOVE. FRONT WILL SLOWLY
BE SAGGING SOUTH ACROSS SOUTHERN WISCONSIN AND WORK INTO ILLINOIS
THROUGH THE OVERNIGHT HOURS. ACTIVITY WILL THEN BE ON THE WANE
AS WE GET CLOSER TO THE MORNING.
THE STRONG WARM AIR ADVECTION THAT SHOT TEMPERATURES INTO THE 80S
TODAY WILL SHIFT SOUTH. WITH THE FRONT DROPPING THROUGH AND ACROSS
CHICAGO...WINDS WILL FLIP AROUND TO THE NORTHEAST AND PULL A
COOLER MARINE AIRMASS ACROSS MUCH OF THE COASTLINE. MODELS CONTINUE
TO SLOW THIS TREND SLIGHTLY OVER PREVIOUS RUNS...BUT DOES CONTINUE TO
KEEP IT DRAPED ACROSS THE AREA. FORECAST SOUNDINGS AND RAW
NUMERICAL GUIDANCE HIGHLIGHTS GOOD INSTABILITY TO PERSIST SOUTH AND
WEST OF THIS FEATURE...THOUGH THE BEST INSTABILITY WILL BE WEST
ACROSS IOWA...AND OVERALL EFFECTIVE SHEAR WILL IS SUGGESTED TO BE AT
OR BELOW 30 KT INTO THE PEAK OF THE AFTERNOON. SPC HAS MOST OF THE
CWA IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW...BUT IT DOES FOLLOW
THE OVERALL LOCATION OF THE FRONT...FAVORING AREAS WITH THE BEST
INSTABILITY. WITH NO REAL FORCING WIGGLING THROUGH THE FLOW
TOMORROW...THE OVERALL THREAT DOES NOT APPEAR TO BE HIGH...BUT
CANNOT RULE OUT THE POSSIBILITY OF SOME UNORGANIZED CELLS DEVELOPING
WITH MARGINAL SEVERE HAIL AND WIND GUSTS.
DID MAKE BIGGER CHANGES TO THE DAYTIME HIGHS ACROSS LAKE AND COOK
COUNTIES. WITH THE FRONT SAGGING SOUTH OF MOST THE METRO INTO THE
EARLY AFTERNOON...SHOULD SEE TEMPS HIT THEIR PEAK IN THE EARLY
AFTERNOON AND THEN FALL. STILL SOME CONSIDERABLE DIFFERENCES BETWEEN
THE MAV AND THE MET THIS AFTERNOON...WITH A 10+ DEGREE DIFFERENCE
BETWEEN THE TWO. THE THOUGHT IS THAT WITH THE FRONT TO THE
SOUTH...MOST COASTAL AREAS /INCLUDING THE CHICAGO METRO/ WILL SEE
HIGHS PEAKING IN THE UPPER 60S TO AROUND 70 BEFORE FALLING INTO THE
AFTERNOON...THOUGH IF MORE RAIN FALLS OVERNIGHT AND KEEPS CLOUDS
IN...MID 60S COULD BE PUSHING IT.
BY THE WEEKEND...UPPER LEVEL RIDGING ACROSS THE FOUR CORNERS REGION
WILL BEGIN TO SHIFT EAST AND OVERHEAD...BUT CONTINUED DISPARITY
BETWEEN LONG RANGE GUIDANCE IS LEADING TO FURTHER LOW END CONFIDENCE
ON PRECIP CHANCES INTO THE NEXT WEEK. TRENDS ARE INDICATING A
WEAK SHORTWAVE ROLLING ACROSS THE RIDGE LATE SUNDAY AND INTO
MONDAY WILL BRING THE NEXT BEST CHANCE FOR SHOWERS. AS THE RIDGE
SLIDES EAST AND A TROUGH MOVES THROUGH...WILL GENERALLY FALL BACK
INTO A COOLER NORTHWESTERLY FLOW REGIME KEEPING DAYTIME HIGHS
CLOSE TO SEASONAL WITH OFF AND ON CHANCES THROUGH THE WEEK.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* CONVECTIVE CHANCES THIS AFTERNOON/EVENING/OVERNIGHT.
* GUSTY SOUTHWEST WINDS THIS AFTERNOON AND EVENING...BECOMING
NORTHEAST FRIDAY.
BMD/KB
//DISCUSSION...UPDATED 20Z...
OVERHAUL TO THE FORECAST THIS AFTERNOON. PREVIOUS CU FIELD THAT
WAS LOOKING SOMEWHAT HEALTHY A COUPLE HOURS AGO HAS DISSIPATED
WITH UPPER LEVEL WAVE OUTRUNNING SURFACE INSTABILITY AND HAVE
DECIDED TO REMOVE MENTION OF THUNDER IN TAFS. WHILE CONFIDENCE IS
NO LONGER HIGH ENOUGH TO CARRY IN TAFS...CHANCES ARE NOT ZERO FOR
THUNDER AND THERE ARE STILL LINGERING CONCERNS. FIRSTLY...AS COLD
POOL CONTINUES TO DEVELOP FROM THUNDERSTORM ACTIVITY OVER SOUTHERN
WISCONSIN...SOME MODEL GUIDANCE SUGGESTS THIS MAY PUSH SOUTH AND
BE FOCUS FOR ADDITIONAL DEVELOPMENT. THUS FAR HOWEVER...THIS HAS
NOT OCCURRED WITH BRISK SOUTHERLY FLOW IMPEDING SOUTHWARD
DEVELOPMENT. SECONDLY...MODEL GUIDANCE SUGGESTS THAT A
THUNDERSTORM COMPLEX MAY DEVELOP TO OUR WEST OVERNIGHT...
HOWEVER...HAVE NO BETTER CONFIDENCE THAN WHAT WE WERE CARRYING IN
THE PROB30 AND HAVE HAD TO REMOVE WITH LATEST AMD. AGAIN...WILL
HAVE TO MONITOR TRENDS CLOSELY...BUT CHANCES SEEM TOO LOW AT THIS
TIME TO CARRY IN FORECAST.
PREVIOUS DISCUSSION...UPDATED 18Z...
MAIN CONCERN WITH THE AFTERNOON TAFS WILL BE DEALING WITH
CONVECTIVE CHANCES THIS AFTERNOON...AND AGAIN THIS EVENING INTO
THE OVERNIGHT HOURS. THIS AFTERNOON... INSTABILITY CONTINUES TO
GROW ACROSS THE REGION BUT THUS FAR REMAINS WELL CAPPED ACROSS
NORTHERN ILLINOIS. MODEL GUIDANCE CONTINUES TO DEVELOP SPURIOUS
PRECIP ACROSS THE AREA...HOWEVER 16Z AND 17Z AMDAR SOUNDING OUT OF
ORD STILL SHOW A FAIRLY STOUT CAP IN PLACE AND TCU FIELD TO THE
WEST WEAKENED AS IT MOVED ACROSS NORTHERN ILLINOIS. CUMULUS FIELD
CONTINUES TO FLUCTUATE TO THE WEST AND WOULD EXPECT EVENTUALLY TO
BE ABLE TO BREAK THROUGH THE CAP...THOUGH NO DISTINCT MECHANISM IS
EVIDENT TO HONE IN ON SPECIFIC TIMING. SHOULD ANYTHING DEVELOP
EARLIER IN THE AFTERNOON...EXPECT COVERAGE TO BE SOMEWHAT ISOLATED
OR WIDELY SCATTERED. THIS EVENING...A MODEST LOW LEVEL JET ALIGNS
FROM SOUTHWESTERN MISSOURI INTO SOUTHERN IOWA AND IS EXPECTED
ALLOW CONVECTIVE ACTIVITY TO EXPAND IN COVERAGE. THUNDERSTORMS ARE
EXPECTED TO TRAIN TO THE ENE ALONG REMNANT OUTFLOW/BAROCLINIC ZONE
AS IT SINKS SOUTH ACROSS THE REGION. IN THE EARLY MORNING HOURS
FRIDAY...EXPECT WINDS TO DIMINISH IN THE FRONTAL TROUGH AND WITH
HIGH DEWPOINTS IN PLACE...COULD SEE VSBY DROP WITH BR/FOG. LATER
IN THE MORNING...EXPECT NORTHEASTERLY WINDS TO SINK SOUTH ACROSS
THE AREA. BMD
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* LOW CONFIDENCE ON THUNDERSTORMS THIS AFTERNOON AND EVENING.
* MEDIUM TO HIGH CONFIDENCE ON WIND TRENDS.
BMD/KB
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT THROUGH TUESDAY...GENERALLY PREVAILING VFR BUT WITH
PERIODIC CHANCES FOR SHRA/TSRA. BEST CHANCES FOR TSRA APPEAR TO BE
FRIDAY INTO THE WEEKEND.
WEDNESDAY...CHANCE SHRA. OTRW...VFR.
KREIN
&&
.MARINE...
223 PM CDT
BROAD LOW PRESSURE WILL EVOLVE EAST ACROSS THE CENTRAL PORTION OF
LAKE MICHIGAN TONIGHT. IN ASSOCIATION WITH THIS FEATURE...CLUSTERS
OF THUNDERSTORMS WILL TRAVERSE ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE...SOME OF THESE POTENTIALLY PRODUCING GUSTY WINDS IN EXCESS OF
35 KTS. GUSTY SOUTHWEST WINDS WILL CONTINUE INTO EARLY THIS EVENING
FROM CHICAGO EASTWARD ACROSS NEARSHORE AREAS...POTENTIALLY
CONTINUING INTO SMALL CRAFT ADVISORY CRITERIA THROUGH 8 OR 9 PM.
THE LOW WILL STEER A COLD FRONT SLOWLY SOUTHWARD ACROSS THE LAKE
TONIGHT INTO FRIDAY MORNING. THIS WILL REACH THE SOUTHERN PORTION OF
THE LAKE BY MIDDAY FRIDAY. NORTHEAST WINDS WILL TURN EAST THIS
WEEKEND AS LOW PRESSURE EVOLVES EASTWARD FROM THE CENTRAL
PLAINS...REACHING THE SOUTHERN GREAT LAKES TO MIDDLE OHIO VALLEY BY
SOMETIME EARLY NEXT WEEK.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM THURSDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1256 PM CDT THU MAY 3 2012
.DISCUSSION...
ISSUED 946 AM CDT THU MAY 3 2012
A BREEZY AND VERY WARM DAY IS UNFOLDING ACROSS CENTRAL ILLINOIS
TODAY. CONVECTIVE COMPLEX OVER NORTHWEST MISSOURI WILL CONTINUE TO
DISSIPATE AS IT TRACKS EASTWARD...WITH LITTLE OR NO PRECIP FROM
THIS SYSTEM EXPECTED TO CROSS THE MISSISSIPPI RIVER. MAIN QUESTION
WILL BE WHETHER OR NOT ANY STORMS CAN FIRE ALONG MESOSCALE BOUNDARIES
ACROSS THE AREA THIS AFTERNOON. FORECAST SOUNDINGS INDICATE A
MODERATELY UNSTABLE ENVIRONMENT WITH LITTLE OR NO CAPPING...SO
ONLY MISSING INGREDIENT WOULD BE A GOOD FOCUSING MECHANISM. IT
APPEARS THE PRIMARY OUTFLOW BOUNDARY FROM THE MISSOURI COMPLEX IS
DROPPING S/SE INTO CENTRAL MISSOURI...HOWEVER OTHER SMALLER SCALE
BOUNDARIES COULD BE PRESENT FURTHER EAST INTO ILLINOIS. AT THIS
TIME...WILL CONFINE AFTERNOON STORM CHANCES TO THE ILLINOIS RIVER
VALLEY WESTWARD. DUE TO MOIST AIRMASS AND STEEP LAPSE RATES...SCT-BKN
CU WILL LIKELY DEVELOP TODAY. CU-RULE SUPPORTS THIS...SO HAVE
UPDATED SKY GRIDS TO GO WITH PARTLY SUNNY WORDING ACROSS MUCH OF
THE AREA. WITH A GOOD DEAL OF SUNSHINE AND STRONG SOUTHERLY WINDS
EXPECTED...AFTERNOON HIGH TEMPS WILL REACH THE MIDDLE TO UPPER 80S
ACROSS THE BOARD.
&&
.AVIATION...
ISSUED 1255 PM CDT THU MAY 3 2012
CU-FIELD WILL CONTINUE TO DEVELOP ACROSS CENTRAL ILLINOIS THIS
AFTERNOON...WITH CU-RULE SUGGESTING SCT-BKN AT AROUND 4000FT. WILL
MONITOR OUTFLOW BOUNDARY ADVANCING EAST OF I-55 FOR POTENTIAL
CONVECTIVE DEVELOPMENT OVER THE NEXT COUPLE OF HOURS...ALTHOUGH
LACK OF CONVERGENCE ALONG SHALLOW BOUNDARY SUPPORTS LITTLE OR NO
DEVELOPMENT. MAIN CONVECTIVE EVENT STILL APPEARS TO BE ON TARGET
FOR LATER THIS EVENING...AS A COLD FRONT SLOWLY SETTLES SOUTHWARD
TOWARD THE REGION. RAP/HRRR MODELS BOTH INDICATE SHOWERS/STORMS
DEVELOPING FROM SOUTHERN WISCONSIN W/SW INTO IOWA LATER THIS
AFTERNOON...THEN SINKING SOUTHWARD INTO NORTH-CENTRAL ILLINOIS
DURING THE EVENING. WITH LOW-LEVEL JET ORIENTED FROM THE SOUTHERN
PLAINS INTO NORTHERN MISSOURI...THINK A MORE ROBUST CLUSTER OF
STORMS WILL DEVELOP AHEAD OF THE APPROACHING FRONT OVER NORTHERN
MISSOURI/SOUTHERN IOWA THIS EVENING...WITH THE COMPLEX TRACKING
EASTWARD ACROSS THE NORTHERN TERMINALS OVERNIGHT. AS SUCH...HAVE
INCLUDED TEMPO GROUPS FOR THUNDER AT BOTH KPIA AND KBMI BETWEEN
03Z AND 08Z. FURTHER SOUTH...HAVE ONLY MENTIONED VCTS AT THE
REMAINING TERMINALS. SOUTHWESTERLY WINDS WILL INITIALLY GUST TO
AROUND 20KT THIS AFTERNOON...THEN WILL BACK TO SOUTHERLY AND
DECREASE TO AROUND 10KT TONIGHT INTO EARLY FRIDAY.
BARNES
&&
.PREV DISCUSSION...
ISSUED 320 AM CDT THU MAY 3 2012
WEAK RIDGING OVER THE EASTERN HALF OF THE CONUS THIS
MORNING...AND SOUTHWESTERLY FLOW OVER MUCH OF THE SOUTHERN PLAINS
AND INTO THE MIDWEST KEEPING A STRING OF CONVECTIVE WAVES MOVING
INTO THE REGION. THIS MORNING...ANOTHER WAVE OVER THE CENTRAL
MISSOURI RIVER VALLEY AND WRN IA EXPECTED TO MOVE INTO THE UPPER
MIDWEST LATER TODAY. FIRST ISSUE FOR THE FORECAST IS THE TIMING OF
THE WAVE...AND THE PRECIP INTO THE CURRENT AIRMASS FOR CENTRAL
ILLINOIS...WHICH BY THE 00Z SOUNDING IS RELATIVELY DRY. MODELS
HAVING A BIT OF AN ISSUE WORKING OUT THE CURRENT CONVECTION...MUCH
LESS ITS PROGRESSION. BOUNDARY SINKING THROUGH TONIGHT AND
INCREASING THE POPS THROUGH TONIGHT AND INTO TOMORROW MORNING.
SHOWERS AND TS CONTINUE THROUGH THE FIRST PORTION OF THE WEEKEND.
CONCERNS STILL FOR WHERE THE BREAKS IN THE PRECIP MAY BE...BEFORE
THE LARGER SCALE TROF OVER THE NWRN CONUS BEGINS TO MOVE OUT...AND
THE SFC LOW DRAGS THROUGH THE MIDWEST MON/MON NIGHT...LEAVING A
BRIEF RESPITE FROM THE RAINFALL IN THE MIDDLE OF THE NEXT WORK
WEEK.
SHORT TERM...TODAY AND TOMORROW...
WARM AND MUGGY CONDITIONS AS SOUTHERLY WINDS USHER WARM AIR INTO
THE MIDWEST. A BIT OF A QUESTION MARK REMAINS THE HIGH TEMPS NW OF
THE ILLINOIS RIVER VALLEY...WHERE CLOUD COVER IS ENHANCED BY DYING
MCS PASSING TO THE NW THIS MORNING. CLOUD COVER/COLD POOL LIKELY TO
INHIBIT THE WARM UP A BIT...THOUGH THE SOUTHERLY WINDS ARE
COUNTERING. MUCH SUNNIER TO THE SOUTH AND EAST OF THE INTERSTATE
55 CORRIDOR...AND TEMPS SOARING INTO THE MID TO UPPER 80S...850MB
TEMPS IN THE 17-18C RANGE...AND MIXING DOWN SOME 20-25MPH GUSTS.
ISSUE FOR THE CURRENT POPS...WHICH THE HRRR IS THE ONLY MODEL TO
REALLY DEPICT WELL...ALBEIT ABOUT 2 HOURS BEHIND AND A LITTLE
UNDERDONE...IS THE ARRIVAL AND POTENTIAL IMPACT TO AREAS IN THE
NRN TIER OF THE STATE AND CWA LATER THIS AFTERNOON. HAVE SLIGHTLY
ADJUSTED SOME HIGHER CHANCE POPS FOR THIS TREND AND MAY NEED TO
KEEP A CLOSE LOOK FOR THIS AFTERNOON IN MORE OF THE HIGH RES
SOLUTIONS. THIS EVENING AND TONIGHT...PRECIP CHANCES INCREASE AS
THE UPPER RIDGE STARTS TO BREAK DOWN AND THE CONVECTION TO THE NW
PUSHES INTO THE FA. MODELS CONTINUE TO PUSH SMALL REINFORCING
SHORTWAVES TO KEEP THE REGION IN PRECIP THROUGH MUCH OF FRIDAY OFF
AND ON.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
POSSIBLE BREAK FOR PART OF SATURDAY IN THE SHOWERY PRECIP...AT
LEAST BEING HINTED IN THE MODELS AS MORE DETAIL WORKS IN...WITH
THE LARGER SCALE SYSTEM PUSHING IN SAT NIGHT WITH THE UPPER LOW ON
THE MOVE ACROSS THE NRN PLAINS. STRONGER SFC LOW ACROSS THE NRN
BOUNDARY OF THE CONUS...DEEP TROF/FRONTAL BOUNDARY TO WEAKER
SOUTHERN SFC LOW PUSHING A BOUNDARY THROUGH THE MIDWEST SUN/MON
AND A RETURN OF THE POPS AGAIN THROUGH THE END OF THE
FORECAST...WITH BEST CHANCES SUN NIGHT THROUGH MON NIGHT FOR MORE
EXTENSIVE RAIN AS THE SFC LOW IS SLIGHTLY SLUGGISH TO MOVE OUT.
ECMWF IS A BIT SLOWER THAN THE GFS...BUT NOT TOO FAR OFF
ALTOGETHER. A SMALL BREAK IN THE HEAT WITH THE SYSTEM AS HIGHS FOR
MON/TUES A BIT LOWER WITH THE MID LEVEL TROF GETTING SOME COOLER
AIR OVHD BEHIND THE RIDGE. COOLER TEMPS CONTINUE THROUGH MIDWEEK
AS THE UPPER TROF SLOWS AS WELL...THOUGH SFC STARTS TO DRY OUT A
BIT WED NIGHT.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
1247 PM CDT THU MAY 3 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
FORECAST CONCERN INVOLVES THE ONGOING CONVECTION ASSOCIATED WITH A
DYING MCS MOVING ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA
THIS MORNING. LATEST HRRR (05Z RUN) HAS CONVECTION DISSIPATING AND
MOVING EAST THROUGH 15Z AND THE 00Z 4KM WRF HAS CONVECTION
DISSIPATING BY AROUND 18Z IN EASTERN PORTIONS OF THE FORECAST AREA.
Q2 CURRENTLY DEPICTING RAINFALL RATES AROUND 2 IN/HR OR LESS WITHIN
THE STRONGER CORES...BUT LINE IS MOVING FAIRLY PROGRESSIVE AT
30-35KTS. SO NOT ANTICIPATING MUCH FLOODING ISSUES...ESPECIALLY
FURTHER EAST WITHIN THE FLASH FLOOD WATCH AREA IN NORTHEAST IOWA.
CONVECTION SHOULD BE MUCH WEAKER BY THE TIME IT REACHES IT AND
THUS...WENT AHEAD AND CANCELLED FLASH FLOOD WATCH.
OTHER CONCERN IS WITH POTENTIAL FOR AFTERNOON CONVECTION ALONG AND
SOUTH OF THE BOUNDARY IN NORTHERN IOWA. RUC/NAM/GFS ALL KEEP THE
SURFACE FRONT LAID UP ALONG THE MN/IA BORDER KEEPING THE FORECAST
AREA WITHIN THE WARM SECTOR. BEST INSTABILITY WILL BE LOCATED SOUTH
OF HIGHWAY 30 WHERE LOW LEVEL CAPE INCREASES TO AROUND 2000-3000
J/KG BUT LOW LEVEL SHEAR VALUES NOT IMPRESSIVE. CLOUDS LEFTOVER FROM
DYING MCS SHOULD LIMIT SOME OF THE DAYTIME HEATING...BUT THINKING
THE WAA WILL BE STRONG ENOUGH TO BUMPED TEMPS BACK INTO THE LOWER
80S BY THIS AFTERNOON. TIMING OF AFTERNOON CONVECTION LOOKS TO BE
AFTER 21Z WITH MID-LEVEL SHORTWAVE MOVING INTO WESTERN IOWA BY 00Z
FRIDAY. SURFACE DEW POINTS REMAIN WELL INTO THE 60S...SO PLENTY OF
MOISTURE AVAILABLE.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
CURRENT LONG WAVE PATTERN...WRN CONUS TROUGH/ERN RIDGE...WILL REMAIN
INTACT THROUGH MUCH OF THE PERIOD BUT WITH SLOW PROGRESS. THIS
SHOULD HAVE TROUGH ONLY REACH CENTRAL CONUS BY EARLY NEXT WEEK.
EXPECT CONVERGENCE FROM CURRENT NE TO MN FRONTAL BOUNDARY AND/OR
OUTFLOW FROM WEAKENING WRN IA MCS TO EVENTUALLY POSITION ITSELF INTO
CENTRAL/SRN IA BY EARLY THIS EVENING AND TRIGGER ANOTHER ROUND OF
CONVECTION...TIMED MUCH LIKE PAST FEW EVENTS MAINLY AT NIGHT. MCS
SHOULD THEN PUSH TO THE SOUTH AND EAST DIMINISHING POPS OVERNIGHT.
CONFIDENCE IN THIS SCENARIO IS SOMEWHAT LOW HOWEVER AS CURRENT MCS
CONTINUES TO BACK BUILD ACROSS SRN NE. FORECASTING EVENTUAL
POSITION OF SYNOPTIC AND/OR MESOSCALE BOUNDARIES WILL BE DIFFICULT.
BY FRI MODEL CONSENSUS SUGGESTS A RELATIVE LULL WITH IA IN FAIRLY
WEAK SELY SURFACE FLOW. STILL UNSTABLE BUT LITTLE FOCUS. ATTENTION
TURNS TO THE WEST AGAIN EYING RESPONSE TO GRADUALLY APPROACHING
WRN TROUGH. THIS WILL LEAD TO INCREASING WARM ADVECTION AND
BAROCLINICITY THROUGH SIOUXLAND MO VALLEY REGION. 305K FLOW IS
FAIRLY WEAK SO DO NOT EXPECT SIGNIFICANT MCS BUT INCREASING POPS.
CONVECTION MAY BE MORE SIGNIFICANT BY SAT NIGHT AND SUNDAY HOWEVER
AS FLOW AND ASSOCIATED THETA-E ADVECTION INCREASE. KINEMATIC
FORCING WILL INCREASE AS WELL AS LOBE OF UVM PUSHES ACROSS NRN
PLAINS INTO EARLY SUN WHICH IS ALSO FOCUSED BY PASSAGE OF INVERTED
SURFACE TROUGH. THIS ALL LEADS TO POPS BACK UP INTO LIKELIES DURING
THIS PERIOD.
BY EARLY NEXT WEEK PATTERN WILL SHIFT SUFFICIENTLY TO LOWER OUR
PRECIP CHANCES AND COOL TEMPS SOMEWHAT AS IA ENDS UP IN NWLY SURFACE
FLOW. THIS RESULTS IN EXTENDED FORECAST EITHER DRY OR WITH ONLY
SLIGHT CHANCES AND MAXES ONLY IN THE 60S OR POSSIBLY LOWER 70S.
&&
.AVIATION...03/18Z
IN WAKE OF MORNING SHRA/TSRA A SMALL AREA OF HIGH PRESSURE HAS
DEVELOPED...CREATING SMALL-SCALE WIND FIELD EFFECTS THAT ARE PROVING
DIFFICULT TO PREDICT WITH WINDS ANYWHERE FROM 170-270 AND FROM
NEARLY CALM TO ABOUT 15G25KT. HAVE TAKEN A BEST GUESS IN THE TAFS
BUT WINDS WILL BE TRICKY UNTIL THE HIGH DISSIPATES. MEANWHILE...MORE
STORMS ANTICIPATED LATE TODAY HAVE A HIGH DEGREE OF UNCERTAINTY.
BEST CHANCES APPEAR TO BE IN OUR FAR NORTH AND FAR SOUTH THIS EVE
WHERE PRONOUNCED BOUNDARIES ARE PRESENT...HOWEVER HAVE SO LITTLE
CONFIDENCE IN TIMING/EXTENT THAT VCTS IS ALL THAT CAN BE JUSTIFIED
IN 18Z TAFS. IN ANY EVENT STORMS SHOULD END BY MIDNIGHT...WITH MVFR
OR LOWER CIGS/VSBYS IN FOG AND STRATUS POSSIBLE DURING THE EARLY
MORNING HOURS FRI WITH LIGHT/VRBL WINDS AND AMPLE LOW-LEVEL MOISTURE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KLP
LONG TERM...BSS
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1238 PM CDT THU MAY 3 2012
...UPDATED AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 234 AM CDT THU MAY 3 2012
THE 03.00Z 250 HPA SYNOPTIC MAP SHOWED A SEGMENTED POLAR JET WITH A
90 KT JET PUSHING ASHORE ACROSS THE PACIFIC NORTHWEST. ANOTHER 110
KT JET STREAK WAS LOCATED ACROSS THE NORTHERN PLAINS WITH THE RIGHT
ENTRANCE REGION FAIRLY CLOSE TO KANSAS (AND COULD HAVE BEEN PARTIALLY
RESPONSIBLE FOR CONVECTION EARLIER). ANOTHER 100 KT JET WAS LOCATED
ACROSS NEW ENGLAND. AT 500 HPA, VERY COLD TEMPERATURES OF -25 TO -31
DEG C WERE OBSERVED ACROSS BRITISH COLUMBIA AND EXTENDING EASTWARDS
ACROSS THE CANADIAN PRAIRIES AND AS FAR SOUTH AS NORTHEASTERN MONTANA.
SEVERAL MID LEVEL SHORTWAVE TROUGH WERE ANALYZED ACROSS THE CONUS MID
ATMOSPHERE. CLOSER TO KANSAS AND IN THE LOWER LEVELS, A WARM AND DRY
PLUME (EML) EXTENDED ACROSS THE KANSAS AND SOUTHWARD INTO THE SOONER/LONE
STAR STATES. AT THE SURFACE, A LOW PRESSURE CENTER WAS LOCATED ACROSS
FAR SOUTHWESTERN KANSAS. A DRYLINE ASSOCIATED WITH THIS SURFACE LOW
EXTENDED ACROSS SOUTHWEST KANSAS AND SOUTHWARD INTO TEXAS. DEWPOINTS
IN THE 60S DEG F WERE EAST OF THIS BOUNDARY. A WEAK COLD FRONT WAS PUSHING
ACROSS EAST CENTRAL COLORADO AND INTO NORTHWEST KANSAS.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 234 AM CDT THU MAY 3 2012
THIS MORNING:
A COLD FRONT IS MOVING ACROSS NORTHWESTERN KANSAS EARLY THIS MORNING.
THIS FRONT WILL MAKE ITS WAY AT LEAST THROUGH 2/3RD`S OF THE REGION
AND STALL ROUGHLY FROM MEADE TO LARNED. HRRR INDICATES SOME POST FRONTAL
STRATUS VIA UPSLOPE FLOW ACROSS INTERSTATE 70 SO HAVE INCREASED CLOUD
COVER AS A RESULT DURING THE MORNING FOR THIS AREA. TODAY WILL START
OUT QUITE MILD AS DEWPOINTS EAST OF THE DRYLINE ARE WELL INTO THE 60S
DEG F. THIS WAS UNDER FORECAST BY SEVERAL OF THE MODELS. NO PRECIPITATION
IS EXPECTED ALONG THE FRONTAL BOUNDARY DUE TO SUBSIDENCE ALOFT/NO UPPER
LEVEL SUPPORT.
TODAY:
THE HOTTEST TEMPERATURES ARE LIKELY SOUTH OF THE FRONTAL WHICH WILL
STALL ACROSS THE AFOREMENTIONED MEADE TO LARNED LINE. LOW TO MID 90S
DEG F ARE POSSIBLE ACROSS SOUTH CENTRAL KANSAS. FURTHER NORTHWEST, THERE
WILL BE ENOUGH INSOLATION AND MIXING TO ALLOW TEMPERATURES TO PEAK INTO
THE MID TO UPPER 80S DEG F.
THIS EVENING:
I HAVE COMPROMISED BETWEEN SEVERAL MODELS AND HAVE SLIGHT POPS ROUGHLY
NORTHWEST FROM A HAYS TO ELKHART LINE. 00Z NAM/WRF/NMM ARE IN FAIRLY
GOOD AGREEMENT WITH THE POSSIBILITY OF UPSLOPE AND FRONTAL RELATED CONVECTION
ACROSS SOUTHEASTERN COLORADO INTO FAR SW/W KANSAS. THE GFS IS A BIT
DIFFERENT WITH BETTER CONVECTIVE CHANCES ALONG INTERSTATE 70. AS A RESULT,
HAVE BLENDED POPS BETWEEN THE MODELS. THERE MAY BE A WEAK MID LEVEL
SHORTWAVE TROUGH AS SEEN ACROSS THE ROCKIES EARLY THIS MORNING THAT
COULD PROVIDE ENOUGH UPPER LEVEL SUPPORT FOR THUNDERSTORMS. OTHERWISE,
UPPER LEVEL SUPPORT TODAY IS QUITE WEAK. FORECAST SOUNDINGS ACROSS
FAR WESTERN KANSAS SHOW ABOUT 1500 J/KG OF CAPE AND A BIT OF VEERING
IN THE WIND PROFILE, ALTHOUGH SPEED SHEAR IS RATHER WEAK. THE THERMODYNAMIC
PROFILE IS WELL MIXED TO ABOUT 600 HPA SO IF CONVECTION DOES FORM, THEN
DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT AND PERHAPS MARGINAL SEVERE
HAIL SINCE 0 TO 6 KM SHEAR IS ONLY FORECAST TO BE ABOUT 25-30 KT. WITH
THIS EXCEPTION OF A VERY MARGINAL CHANCE OF AN ISOLATED THUNDERSTORM,
THE FORECAST WILL REMAIN DRY. OVERNIGHT LOWS HEADING INTO FRIDAY MORNING
WILL BE MILD AGAIN WITH 50S DEG F TOWARDS GARDEN CITY AND 60S DEG F
TOWARDS MEDICINE LODGE DUE TO MODERATE DEWPOINTS AND WEAK LEE TROUGH/RESULTANT
SOUTHERLY WINDS THROUGH THE OVERNIGHT PERIOD.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 309 AM CDT THU MAY 3 2012
BOTH THE NAM AND GFS ARE IN GOOD AGREEMENT WITH A SUBTLE UPPER
LEVEL DISTURBANCE CROSSING SOUTHWEST KANSAS EARLY IN THE DAY ON
FRIDAY. AS THIS SYSTEM CROSSES WESTERN KANSAS A SURFACE BOUNDARY
WILL EXTEND FROM WEST TO EAST NORTH OF INTERSTATE 70 AND A DRYLINE
IS EXPECTED TO STRETCH FROM THIS SURFACE BOUNDARY SOUTH INTO
WESTERN OKLAHOMA. AT THIS TIME BASED ON THE TIMING OF THIS SUBTLE
FEATURE AND WARM MID LEVEL TEMPERATURES FORECAST FRIDAY AFTERNOON
WILL CONTINUE TO FAVOR A DRY FORECAST FRIDAY AND FRIDAY NIGHT
ACROSS WESTERN KANSAS. MODEL SOUNDINGS INDICATING A DECENT MIXING
DEPTH AND BASED ON 850MB TEMPERATURES AT 00Z SATURDAY WILL
CONTINUE TO FAVOR HIGHS AT LEAST IN THE LOW TO MID 90S.
A STRONGER UPPER LEVEL TROUGH WILL BEGIN TO CROSS WESTERN UNITED
STATES LATE FRIDAY. AN UPPER LEVEL JET IS FORECAST TO BEGIN TO
MOVE FROM THE BASE OF THIS TROUGH AND EJECT OUT INTO THE WEST
CENTRAL HIGH PLAINS BY EARLY THIS WEEKEND. AS THIS NEXT SYSTEM
APPROACHES EARLY THIS WEEKEND AN AREA OF LOW PRESSURE IS EXPECTED
TO DEEPEN ACROSS EASTERN COLORADO/WESTERN KANSAS. BY 00Z SUNDAY
700MB TEMPERATURES ACROSS WESTERN KANSAS ARE FORECAST TO RANGE
FROM +10 TO +12C AND THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL
JET IS EXPECTED TO BE LOCATED NEAR NORTHEAST COLORADO. BASED ON
THE LOCATION OF THE UPPER JET, 925-850MB THETA-E RIDGE
AXIS/MOISTURE ADVECTION AND NORTHERN EDGE OF THE WARM 700MB
TEMPERATURES WILL FAVOR LATE DAY AND EARLY SATURDAY NIGHT
CONVECTION STAYING NORTH OF THE AREA. TEMPERATURES SATURDAY WILL
ONCE AGAIN BE WARM AND BASED ON 850MB TEMPERATURES AND THE
FORECAST MIXED LAYER THE HIGHS SATURDAY AFTERNOON SHOULD CLIMB
ONCE AGAIN BACK INTO THE LOW TO MID 90S.
BY EARLY SUNDAY THE UPPER JET WILL MOVE OUT INTO THE NORTHERN
PLAINS AND A COLD FRONT IS FORECAST TO SURGE SOUTH INTO WESTERN
KANSAS. A TIGHT SURFACE PRESSURE GRADIENT AND STRONG BOUNDARY
LAYER TO 850MB WINDS ARE FORECAST BEHIND THIS FRONT WITH A NET 24
HOUR 850MB TEMPERATURE CHANCE FROM 00Z SUNDAY TO 00Z MONDAY
AVERAGING FROM 8-12C DEGREES COOLER. AS A RESULT WILL UNDERCUT MAX
TEMPERATURES ON SUNDAY AND TREND TOWARDS THE COOLER 00Z MONDAY
ECMWF/GFS 850MB MIX DOWN TEMPERATURES. MOISTURE SOMEWHAT LIMITED
WITH THIS FRONT AND UPPER LEVEL DYNAMICS APPEAR TO REMAIN NORTH OF
THE AREA SO PRECIPITATION CHANCES STILL APPEAR SMALL BUT DID
INSERT SOME SMALL POPS EARLY SUNDAY NEAR AND NORTH OF INTERSTATE
70.
ON MONDAY ISENTROPIC LIFT/850-700MB WARM AIR ADVECTION BEGINS TO
IMPROVE ACROSS EASTERN COLORADO AND WESTERN KANSAS. ON MONDAY
NIGHT ANOTHER UPPER LEVEL TROUGH WILL BEGIN TO APPROACH THE WEST
CENTRAL PLAINS WHICH SHOULD PROVIDE THE NEXT DECENT OPPORTUNITY
FOR MEASURABLE PRECIPITATION TO PORTIONS OF WESTERN KANSAS TUESDAY
AND WEDNESDAY AS MOISTURE AND ISENTROPIC LIFT/WARM AIR ADVECTION
CONTINUES ACROSS WESTERN KANSAS. IN ADDITION GIVEN THE CLOUD COVER
EXPECTED TUESDAY AND WEDNESDAY WILL CONTINUE TO FAVOR THE PREVIOUS
FORECAST WITH HIGHS MAINLY IN THE UPPER 60S TO LOWER
70S...ESPECIALLY ON TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1238 PM CDT THU MAY 3 2012
NORTHERLY WINDS AT GARDEN CITY AND DODGE CITY LATE THIS MORNING
WILL DECREASE AND GRADUALLY SWING AROUND TO THE EAST AND SOUTHEAST
LATER THIS AFTERNOON WHILE AT HAYS, WINDS SHOULD REMAIN LIGHT AND
VARIABLE. ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE
COLORADO FRONT RANGE THIS AFTERNOON AND COULD MOVE INTO FAR
WESTERN KANSAS THIS EVENING. THE STORMS ARE EXPECTED TO DISSIPATE
BEFORE THEY WOULD HAVE ANY IMPACT ON TAF SITES IN SOUTHWEST
KANSAS. WEAK MOIST UPSLOPE FLOW COULD RESULT IN LOW LEVEL STRATUS
AROUND HAYS LATE TONIGHT INTO EARLY FRIDAY MORNING.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 88 56 95 61 / 10 10 0 0
GCK 86 55 94 58 / 10 20 0 0
EHA 89 56 94 59 / 20 20 0 0
LBL 89 58 96 60 / 10 10 0 0
HYS 85 60 93 62 / 10 20 0 10
P28 93 66 93 66 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SUGDEN
SHORT TERM...SUGDEN
LONG TERM...BURGERT
AVIATION...GERARD
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
253 PM EDT THU MAY 3 2012
.SYNOPSIS...
AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION TONIGHT
INTO FRIDAY BEFORE A BACKDOOR COLD FRONT WILL MOVE THROUGH THE
REGION FRIDAY NIGHT. CANADIAN HIGH PRESSURE BUILDS SOUTHWARD THIS
WEEKEND BEFORE MOVING OFF THE MID-ATLANTIC COAST MONDAY.
&&
.NEAR TERM /TONIGHT/...
A SPL 18Z BALLOON WAS LAUNCHED - ONLY AS A TEST BUT THERE IS UPPER
AIR DATA.
AFTR A MRNG WHERE MUCH OF THE MID ATLC RGN WAS OVC IN LOW CLDS A
RAPID CLRG TOOK PLACE DURG LATE MRNG LVG CWA UNDER M SUN SKIES.
TEMPS NOW RISING...AND MUCH OF CWA SHOULD REACH THE 80S DURG THE
NEXT FEW HRS.
A FEW RW HV BEGUN TO SPRING UP OVR THE HIGHER TERRAIN. HRRR RUC
SHOWS A MORE DVLPD LN OF CNVCTN DVLPG OVR THE MTNS OF PA/MD/VA
DURG THE LATE AFTN BUT WEAKENING AS IT MOVES E. I CAN`T CLAIM TO
HV GREAT CONFIDENCE THAT THE SCENARIO WL UNFOLD EXACTLY LK THIS-
18Z SNDG SHOWS A WEAK WIND FIELD. MDL SNDGS ARE VARYING WIDELY ON
THE AMT OF CAPE THAT WL BE AVBL. SVR THREAT APPEARS MARGINAL AT
BEST...BUT OF COURSE WE HV A RDR OPERATOR KEEPING AN EYE ON
THINGS.
BY LATE EVE CNVCTN SHOULD BE DYING DOWN. IF ANY CNVCTV THREAT
RMNS IT SHOULD BE W OF THE BLUE RDG.
LATE TNGT THERE COULD BE ANOTHER RESURGENCE OF LO LVL
MOISTURE...BRINGING LOW CLDS BACK TO THE NERN PART OF THE CWA.
BOTH NAM AND GFS DEPICT A LOW LVL INVERSION SETTING UP AT BWI
TNGT...AS THESE DID LAST NGT. HOWEVER DO NOT FEEL TNGT`S LOW CLD
XPRNC WL BE AS WIDESPREAD AS LAST NGTS.
LOWS TEMPS MAINLY IN THE L60S...XCPT MU50S IN NERN MD AND OVR THE HIGHLANDS.
&&
.SHORT TERM /FRIDAY/...
A COLD FNT WL MOVE TO A POSN NEAR THE ERN GRT LKS FRI MRNG. THE SWD
PROGRESSION WL BE VERY SLOW...SO MID ATLC LOOKS TO BE IN THE WARM
SECTOR THRUT FRI. TEMPS SHOULD MAKE IT INTO THE MU80S DURG THE
AFTN. MUCH LK THIS AFTN WIND FIELD IS NOT THAT STRONG. GFS IMPLIES
A SHORT WV TRACKING E OF THE APLCHS LATE TMRW WHICH WOULD HELP
INITIATE CNVCTN. THE NERN PART OF THE CWA IS OUTLOOKED W/ A SLT
RISK. BLV LARGE/GUSTY WINDS WOULD BE THE PRIMARY CONSIDERATIONS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
BACKDOOR COLD FRONT OVER PA WILL SAG SWD THRU THE CWA FRI NGT.
ONGOING CONVECTIVE ACTIVITY FROM FRI AFTN WILL LIKELY CONTINUE INTO
THE EVE UNTIL DAYTIME INSTABILITY WANES AROUND SUNSET. IF THE WRN
SECTOR OF FRONT BECOMES HELD UP NEAR THE MTS...WHICH SEEMS PLAUSIBLE
GIVEN SHALLOW NATURE OF THE BOUNDARY...SHOWERS ACTIVITY MAY LINGER
NEAR THE ALLEGHENY FRONT DURING THE OVNGT.
THE FRONT IS EXPECTED TO BE JUST SOUTH OF THE AREA BY SAT MRNG.
THERE ARE STILL MODEL DIFFERENCES WITH ARRIVAL OF THE DRIER/COLDER
AIR IN WAKE OF FROPA...BUT DIFFERENCES ARE CONSIDERABLY SMALLER THAN
24-HR AGO. APPRECIABLE DRY ADVECTION MAY BE DELAYED 6-12 HR POST SFC
FROPA... WHICH COULD KEEP SHOWERS/STORMS IN THE FCST DURING THE DAY
ON SAT AS A MID-LVL SHORTWAVE TROUGH MOVES THRU. THE BEST CHANCE FOR
SHOWERS WILL BE ACROSS CENTRAL VA AND SRN MD...WHILE NRN LOCALES
NEAR THE MASON-DIXON LINE MAY DRY OUT IN THE AFTN.
CANADIAN HIPRES NOSES SWD INTO THE MID-ATLANTIC STATES SAT NGT AND
SUN BEFORE SHIFTING OFF THE COAST MON. THE DRIEST PERIOD DURING THE
ENTIRE 7-DAY FCST APPEARS TO BE THE LATE WEEKEND AND BEGINNING OF
NEXT WEEK. HOWEVER...ELY/UPSLOPE FLOW AROUND THE HIGH MAY PRODUCE
ENOUGH LIFT FOR ISO SHOWERS ACROSS THE SRN POTOMAC HIGHLANDS SUN.
WX PATTERN BECOMES INCREASINGLY UNSETTLED BY MON NGT OR TUE AS A
SHORTWAVE TROUGH APPROACHES FROM THE OH VLY. A MORE POTENT NR-
STREAM TROUGH IS FCST TO DIG SWD INTO THE GREAT LAKES/OH VLY
MIDWEEK. WITH THE MID-ATLANTIC SITUATED IN UNSTABLE WARM SECTOR...
SCT SHOWERS AND STORMS LIKELY THRU WED.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR CONDS THIS EVE. LOW ST COULD AGN DVLP LATE TNGT...ALTHO NOT AS
WIDESPREAD AS LAST NGT. MVFR CIGS MOST LKLY AT BWI/MTN.
TSTMS PSBL FRI AFTN. ALL XCPT CHO COULD SEE STORMS BY LATE FRI AFTN.
COLD FRONT MOVING SWD WILL CROSS THE TERMINALS FRI NGT. SCT SHOWERS
AND STORMS CONTINUE ERY FRI EVE WILL DIMINISH AFTER SUNSET. ENOUGH
SFC INSTABILITY MAY DEVELOP ON SAT FOR ISO-SCT SHOWERS/TSTMS TO
DEVELOP ON SAT. SLIGHTLY BETTER CHANCES FOR CONVECTIVE ACTIVITY WILL
BE NEAR CHO.
NELY COMPONENT TO THE FLOW MAY ADVECT MARINE LAYER INLAND SUN AS
HIPRES BUILDS SEWD. A FASTER PROGRESSION OF THE HIGH WOULD FAVOR A
MORE ELY COMPONENT TO THE FLOW AND INLAND ADVECTION OF LOW STRATUS
SUN MRNG.
&&
.MARINE...
WINDS TO RMN BLO SCA VALUES TNGT AND FRI. XCPTN WOULD BE IF TSTMS
DVLP FRI AFTN.
COLD FRONT WILL MOVE SWD THRU THE WATERS FRI NGT. THREAT OF STRONG
TSTMS WILL CONTINUE ACROSS THE WATERS FRI EVE BEFORE STORMS WEAKEN
AFTER SUNSET. WINDS WILL BE LGT THRU THE WEEKEND.
SLY FLOW INCREASES ERY NEXT WEEK AS HIPRES SHIFTS OFF THE EAST
COAST. WINDS MAY INCREASE TO SCA LVLS LATE MON INTO TUE...BUT STILL
CONSIDERABLE UNCERTAINTY THIS FAR OUT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
PRODUCTS...WOODY!/JRK
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1145 AM MDT THU MAY 3 2012
UPDATED AVIATION
.UPDATE...
NO SIGNIFICANT CHANGES TO THE FORECAST FOR THIS MORNING. HAVE
UPDATED POPS ACROSS CENTRAL MONTANA FOR THE AFTERNOON
HOURS...SLIGHTLY RAISING POPS WHERE THE RUC AND HRRR MODELS HAVE
BOTH EMPHASIZED A BETTER CHANE OF AFTERNOON SHOWERS. OTHERWISE
FORECAST REMAINS ON TRACK. SUK
&&
.AVIATION...
UPDATED 1800Z.
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON
AFTER 20Z AS MOIST AND UNSTABLE SOUTHWEST FLOW SPREADS INTO THE
AREA. THESE SHOWERS AND THUNDERSTORMS MAY PRODUCED LOCALIZED MVFR
CONDITIONS IN HEAVIER RAINFALL. GUSTY ERRATIC WINDS AND SMALL HAIL
ARE ALSO POSSIBLE WITH SOME STRONGER STORMS. THIS ACTIVITY WILL
DECREASE AFTER SUNSET. BREEZY SOUTHEAST WINDS THIS AFTERNOON WILL
SHIFT MORE SOUTHWESTERLY AS AN UPPER-LEVEL TROUGH OF LOW PRESSURE
MOVES TOWARDS THE AREA. MLV
&&
.HYDROLOGY...
THE SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED ACROSS THE AREA
THROUGH FRIDAY MAY PRODUCE BRIEF HEAVY RAINFALL AT TIMES...WHICH
MAY CAUSE BRIEF LOCALIZED FLOODING CONCERNS FOR SMALL STREAMS AND
CREEKS. TEMPERATURES ARE NOT EXPECTED TO BECOME UNUSUALLY WARM
FOR THIS TIME OF YEAR...SO RAPID AND SIGNIFICANT MELTING OF
MOUNTAIN SNOWPACK IS UNLIKELY. STEADY SNOWMELT WILL KEEP WATERWAYS
RUNNING HIGH...BUT FLOODING OF MAIN STEM RIVERS IS NOT FORECAST AT
THIS TIME. A LARGER SCALE SYSTEM WILL LIKELY BRING MORE
WIDESPREAD PRECIPITATION TO THE AREA FOR SATURDAY AND
SUNDAY...WHICH MAY CAUSE RIVERS TO RISE FURTHER. WILL THEREFORE
CONTINUE TO MONITOR THE SITUATION FOR THE NEXT SEVERAL DAYS FOR
POTENTIAL HYDROLOGIC HIGHLIGHTS. COULSTON
&&
.PREV DISCUSSION...
/ISSUED 550 AM MDT THU MAY 3 2012/
TODAY THROUGH SATURDAY...THE UPPER LEVEL TROUGH OF LOW PRESSURE
POSITIONED ALONG THE PACIFIC COAST WILL CONTINUE THE MOIST AND
UNSTABLE SOUTHWESTERLY FLOW ALOFT OVER THE TFX CWA THROUGH
FRIDAY. ONE WEAK SHORTWAVE TROUGH WILL BRING A GOOD CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE AREA ONCE AGAIN FOR LATER THIS
AFTERNOON THROUGH THE EVENING HOURS. THE UPPER LEVEL TROUGH WILL
THEN MOVE INTO THE PACIFIC NORTHWEST ON FRIDAY...AS MOISTURE AND
ENERGY AHEAD OF THE TROUGH COMBINE TO BRING ANOTHER GOOD CHANCE
OF SHOWERS AND THUNDERSTORMS TO THE AREA. THE AIRMASS WILL BE
SLIGHTLY MORE UNSTABLE ACROSS SOUTHWEST MONTANA ON FRIDAY THAN
WHAT IS EXPECTED TODAY...SO THE THREAT FOR SMALL HAIL AND GUSTY
WINDS THERE WILL BE SLIGHTLY GREATER ON FRIDAY.
OVERALL...THOUGH...THE MAIN THREAT FROM THUNDERSTORMS BOTH DAYS
WILL BE BRIEF HEAVY RAINFALL. TEMPERATURES BOTH DAYS WILL BE NEAR
TO SLIGHTLY ABOVE NORMAL AS AN INVERTED SURFACE TROUGH BUILDS
OVER THE AREA...ADVECTING WARMER AIR INTO THE AREA. THE UPPER
LEVEL TROUGH WILL THEN MOVE THROUGH AREA ON SATURDAY...PRODUCING A
BETTER CHANCE OF WIDESPREAD PRECIPITATION. THE INVERTED SURFACE
TROUGH WILL MOVE EAST OF THE AREA AS A COLD FRONT FRIDAY NIGHT
INTO SATURDAY...AND THE COOLER CANADIAN AIRMASS IN ITS WAKE WILL
COOL TEMPERATURES TO BETWEEN 10 AND 15 DEGREES COOLER THAN NORMAL.
THIS COOLER AIR WILL ALSO WEAKEN THE INSTABILITY OVER THE AREA
FOR LESS OF A CHANCE FOR THUNDERSTORMS. THIS SYSTEM WILL ALSO
LOWER SNOW LEVELS DOWN TO BETWEEN 5500 AND 6500 FEET ACROSS THE
AREA...FOR A BETTER CHANCE OF MEASURABLE SNOWFALL IN THE
MOUNTAINS AS WELL. THIS SITUATION WILL CONTINUE TO BE MONITORED
FOR POSSIBLE WINTER WEATHER HIGHLIGHTS...MAINLY FOR THE
MOUNTAINS. COULSTON
SATURDAY NIGHT THROUGH THURSDAY...MEDIUM RANGE MODELS CONTINUE TO
HAVE QUITE SUBSTANTIAL DIFFERENCES IN THEIR SOLUTIONS FOR
SATURDAY NIGHT AND SUNDAY. AS BEFORE...THE GFS IS SLOWER...DEEPER
AND WETTER WITH THE UPPER LEVEL SYSTEM THAN THE ECMWF. THE MOST
RECENT RUN OF THE GFS HAS SLOWED THE SYSTEM EVEN MORE THAN
EARLIER RUNS AND KEEPS THE INFLUENCE OF THE UPPER TROUGH OVER THE
FORECAST AREA CLEAR INTO TUESDAY. AT THIS TIME I FEEL COMFORTABLE
KEEPING THE EARLY PART OF THE MEDIUM RANGE PERIOD COOL AND WET IN
KEEPING WITH THE GFS. HOWEVER...BELIEVE THIS LATEST RUN IS
KEEPING THE LOW IN THE REGION TOO LONG SO HAVE TRENDED MORE
TOWARD THE ECMWF FOR TUESDAY AND BEYOND WITH AN UPPER LEVEL RIDGE
EXPECTED TO BUILD OVER THE NORTHERN ROCKIES FOR WARMER AND DRIER
CONDITIONS. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 61 39 61 37 / 30 40 30 50
CTB 58 34 58 34 / 20 60 20 20
HLN 61 37 60 35 / 40 30 50 50
BZN 62 35 61 33 / 40 30 50 40
WEY 50 28 51 26 / 60 40 40 30
DLN 58 33 58 30 / 50 30 50 50
HVR 65 37 65 37 / 10 60 20 40
LWT 58 35 59 34 / 20 60 40 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1045 AM MDT THU MAY 3 2012
.UPDATE...
NO SIGNIFICANT CHANGES TO THE FORECAST FOR THIS MORNING. HAVE
UPDATED POPS ACROSS CENTRAL MONTANA FOR THE AFTERNOON
HOURS...SLIGHTLY RAISING POPS WHERE THE RUC AND HRRR MODELS HAVE
BOTH EMPHASIZED A BETTER CHANE OF AFTERNOON SHOWERS. OTHERWISE
FORECAST REMAINS ON TRACK. SUK
&&
.AVIATION...
UPDATED 1150Z.
VFR CONDITIONS ARE GENERALLY EXPECTED ACROSS THE AREA THROUGH AT
LEAST 12Z FRIDAY...UNLESS OTHERWISE SPECIFIED. A DISTURBANCE IN THE
MOIST AND UNSTABLE SOUTHWEST FLOW ALOFT WILL SPREAD SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE AREA FROM THE
SOUTHWEST...BEGINNING AFTER 16Z IN SOUTHWEST MONTANA (KBZN). THESE
SHOWERS AND THUNDERSTORMS MAY PRODUCE LOCALIZED MVFR CONDITIONS IN
HEAVIER RAINFALL. THE SHOWERS/STORMS WILL THEN DECREASE FROM THE
SOUTHWEST AFTER 00Z AS THE DISTURBANCE BEGINS EXITING THE
AREA...WITH MOST ACTIVITY OUT OF THE AREA BY 04Z. A SURFACE TROUGH
WILL ALSO MOVE WEST THROUGH THE AREA AFTER 21Z...CAUSING BREEZY
SOUTHEAST WINDS TO SHIFT MORE SOUTHWESTERLY THROUGH AROUND
06Z...WITH DECREASING WINDS OVERNIGHT. COULSTON
&&
.HYDROLOGY...
THE SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED ACROSS THE AREA
THROUGH FRIDAY MAY PRODUCE BRIEF HEAVY RAINFALL AT TIMES...WHICH
MAY CAUSE BRIEF LOCALIZED FLOODING CONCERNS FOR SMALL STREAMS AND
CREEKS. TEMPERATURES ARE NOT EXPECTED TO BECOME UNUSUALLY WARM
FOR THIS TIME OF YEAR...SO RAPID AND SIGNIFICANT MELTING OF
MOUNTAIN SNOWPACK IS UNLIKELY. STEADY SNOWMELT WILL KEEP WATERWAYS
RUNNING HIGH...BUT FLOODING OF MAIN STEM RIVERS IS NOT FORECAST AT
THIS TIME. A LARGER SCALE SYSTEM WILL LIKELY BRING MORE
WIDESPREAD PRECIPITATION TO THE AREA FOR SATURDAY AND
SUNDAY...WHICH MAY CAUSE RIVERS TO RISE FURTHER. WILL THEREFORE
CONTINUE TO MONITOR THE SITUATION FOR THE NEXT SEVERAL DAYS FOR
POTENTIAL HYDROLOGIC HIGHLIGHTS. COULSTON
&&
.PREV DISCUSSION...
/ISSUED 550 AM MDT THU MAY 3 2012/
TODAY THROUGH SATURDAY...THE UPPER LEVEL TROUGH OF LOW PRESSURE
POSITIONED ALONG THE PACIFIC COAST WILL CONTINUE THE MOIST AND
UNSTABLE SOUTHWESTERLY FLOW ALOFT OVER THE TFX CWA THROUGH
FRIDAY. ONE WEAK SHORTWAVE TROUGH WILL BRING A GOOD CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE AREA ONCE AGAIN FOR LATER THIS
AFTERNOON THROUGH THE EVENING HOURS. THE UPPER LEVEL TROUGH WILL
THEN MOVE INTO THE PACIFIC NORTHWEST ON FRIDAY...AS MOISTURE AND
ENERGY AHEAD OF THE TROUGH COMBINE TO BRING ANOTHER GOOD CHANCE
OF SHOWERS AND THUNDERSTORMS TO THE AREA. THE AIRMASS WILL BE
SLIGHTLY MORE UNSTABLE ACROSS SOUTHWEST MONTANA ON FRIDAY THAN
WHAT IS EXPECTED TODAY...SO THE THREAT FOR SMALL HAIL AND GUSTY
WINDS THERE WILL BE SLIGHTLY GREATER ON FRIDAY.
OVERALL...THOUGH...THE MAIN THREAT FROM THUNDERSTORMS BOTH DAYS
WILL BE BRIEF HEAVY RAINFALL. TEMPERATURES BOTH DAYS WILL BE NEAR
TO SLIGHTLY ABOVE NORMAL AS AN INVERTED SURFACE TROUGH BUILDS
OVER THE AREA...ADVECTING WARMER AIR INTO THE AREA. THE UPPER
LEVEL TROUGH WILL THEN MOVE THROUGH AREA ON SATURDAY...PRODUCING A
BETTER CHANCE OF WIDESPREAD PRECIPITATION. THE INVERTED SURFACE
TROUGH WILL MOVE EAST OF THE AREA AS A COLD FRONT FRIDAY NIGHT
INTO SATURDAY...AND THE COOLER CANADIAN AIRMASS IN ITS WAKE WILL
COOL TEMPERATURES TO BETWEEN 10 AND 15 DEGREES COOLER THAN NORMAL.
THIS COOLER AIR WILL ALSO WEAKEN THE INSTABILITY OVER THE AREA
FOR LESS OF A CHANCE FOR THUNDERSTORMS. THIS SYSTEM WILL ALSO
LOWER SNOW LEVELS DOWN TO BETWEEN 5500 AND 6500 FEET ACROSS THE
AREA...FOR A BETTER CHANCE OF MEASURABLE SNOWFALL IN THE
MOUNTAINS AS WELL. THIS SITUATION WILL CONTINUE TO BE MONITORED
FOR POSSIBLE WINTER WEATHER HIGHLIGHTS...MAINLY FOR THE
MOUNTAINS. COULSTON
SATURDAY NIGHT THROUGH THURSDAY...MEDIUM RANGE MODELS CONTINUE TO
HAVE QUITE SUBSTANTIAL DIFFERENCES IN THEIR SOLUTIONS FOR
SATURDAY NIGHT AND SUNDAY. AS BEFORE...THE GFS IS SLOWER...DEEPER
AND WETTER WITH THE UPPER LEVEL SYSTEM THAN THE ECMWF. THE MOST
RECENT RUN OF THE GFS HAS SLOWED THE SYSTEM EVEN MORE THAN
EARLIER RUNS AND KEEPS THE INFLUENCE OF THE UPPER TROUGH OVER THE
FORECAST AREA CLEAR INTO TUESDAY. AT THIS TIME I FEEL COMFORTABLE
KEEPING THE EARLY PART OF THE MEDIUM RANGE PERIOD COOL AND WET IN
KEEPING WITH THE GFS. HOWEVER...BELIEVE THIS LATEST RUN IS
KEEPING THE LOW IN THE REGION TOO LONG SO HAVE TRENDED MORE
TOWARD THE ECMWF FOR TUESDAY AND BEYOND WITH AN UPPER LEVEL RIDGE
EXPECTED TO BUILD OVER THE NORTHERN ROCKIES FOR WARMER AND DRIER
CONDITIONS. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 61 39 61 37 / 30 40 30 50
CTB 58 34 58 34 / 20 60 20 20
HLN 61 37 60 35 / 40 30 50 50
BZN 62 35 61 33 / 40 30 50 40
WEY 50 28 51 26 / 60 40 40 30
DLN 58 33 58 30 / 50 30 50 50
HVR 65 37 65 37 / 10 60 20 40
LWT 58 35 59 34 / 20 60 40 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SUK
LONG TERM...MPJ
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
124 PM CDT THU MAY 3 2012
.UPDATE...
EARLY AFTERNOON UPDATE TO REDUCE POPS A BIT THIS AFTERNOON.
&&
.DISCUSSION...
COMPLEXITY OF AFTERNOON/THIS EVENING CONVECTIVE FORECAST REMAINS
HIGH WITH SEVERAL WEAK BOUNDARIES EXTENDING ACROSS THE REGION. A
FEW BOUNDARIES STICK OUT...THE FIRST OF WHICH IS THE MAIN
SYNOPTIC BOUNDARY EXTENDING FM LOW PRESURE OVER SOUTH CENTRAL
KANSAS TOWARD KOFK...KLCG AND JUST NORTH OF KSUX. SOUTH OF
THIS...VERY MOIST AIRMASS REMAINS IN PLACE ALLOWING FOR AN
UNSTABLE AIRMASS WITH SFC TEMPS INTO THE MID TO UPPER 70S. HAVE
HAD TO ADJUST SKY GRIDS THIS AFTERNOON FOR EXPANDING STRATUS DECK
OVER OUR FAR SOUTHWESTERN COUNTIES BUT DO EXPECT THIS TO SCATTER
OUT AS WAS THE CASE YESTERDAY WITH INCREASED AFTERNOON HEATING.
SECOND BOUNDARY TO MENTION IS LEFT OVER OUTFLOW BOUNDARY ACROSS
ERN KS/WRN MO WHICH SHOULD PUSH NORTH. MILLION DOLLAR
QUESTION...LIKE YESTERDAY...IS WHETHER OR NOT IF/WHEN ANY
CONVECTION WILL BE ABLE TO FORM ALONG THE OUTFLOW BOUNDARY AS
SHORT TERM MODELS CONTINUE TO INDICATE...LIKE WAS THE CASE YESTERDAY.
WEAK UPPER LEVEL SUPPORT IS FORECAST TO PROGRESS INTO SOUTHEAST
NEB AROUND 00Z AND COULD BE THE FOCUS TIME FOR CONVECTIVE
INITIATION ACROSS SOUTHEAST NEB. AGAIN...FORECAST CONFIDENCE IS
LOW REGARDING THE LATE AFTERNOON/EVENING CONVECTION.
&&
.AVIATION...18Z TAFS FOR KOFK...KOMA AND KLNK.
VFR TO MVFR CONDITIONS WILL CONTINUE THRU THE TAF PERIOD WITH
TSTMS MOST PROBABLE THIS EVENING AT KLNK AND KOMA. SFC WINDS WILL
REMAIN LIGHT WITH SEVERAL LITTLE BOUNDARIES OVER THE AREA.
&&
.PREV DISCUSSION... /ISSUED 405 AM CDT THU MAY 3 2012/
DISCUSSION...
STRENGTH AND COVERAGE OF CONVECTION SHOULD BE THE PRIMARY FORECAST
CONCERNS THE NEXT FEW DAYS.
UPPER AIR CHARTS FROM LAST EVENING SHOWED THE FOLLOWING. A 300 MB
JET MAX OF AROUND 110 KNOTS EXTENDED FROM NORTH DAKOTA INTO NORTHERN
MINNESOTA AND THEN INTO ONTARIO CANADA. A STRONGER JET CORE OF
AROUND 140 KNOTS WAS PUNCHING TOWARD THE CALIFORNIA COAST. AT 500 MB
SOUTHWESTERLY FLOW WAS IN PLACE FROM THE ROCKIES INTO THE NORTHERN
AND CENTRAL PLAINS. SEVERAL WEAK DISTURBANCES WERE NOTED IN THE FLOW.
PLENTY OF LOW LEVEL MOISTURE WAS IN PLACE FROM THE GULF COAST
NORTHWARD INTO IOWA AND EASTERN NEBRASKA...WITH 850 MB DEWPOINTS
AS HIGH AS THE MID TEENS CELSIUS AT KTOP AND KOAX. SURFACE
ANALYSIS EARLY THIS MORNING WAS SOMEWHAT COMPLEX DUE TO OUTFLOW
BOUNDARIES BUT LOW PRESSURE CENTERS WERE NOTED OVER EASTERN SOUTH
DAKOTA AND WESTERN KANSAS. A DRYLINE EXTENDED SOUTH FROM THE
KANSAS LOW AND A WEAKLY ORGANIZED STATIONARY FRONT APPEARED TO
STRETCH FROM NORTHEAST NEW MEXICO INTO NORTHERN WISCONSIN. SURFACE
DEWPOINTS WERE MOSTLY IN THE 60S SOUTH/EAST OF THE FRONT AND EAST
OF THE DRYLINE.
ONGOING CONVECTIVE COMPLEX WILL LIKELY LINGER INTO MID MORNING FOR
PARTS OF THE AREA...AS SUPPORTED BY RECENT RUNS OF THE HRRR MODEL.
LATER TODAY...HAVE A DRY PERIOD GOING FOR A WHILE...THEN INCREASED
THUNDERSTORM CHANCES FOR THE MID AND LATE AFTERNOON...SIMILAR TO
THE PREVIOUS FORECAST. SOUTHWEST MID LEVEL FLOW WILL BE IN PLACE
AND IT APPEARS SURFACE BOUNDARY MAY PROVIDE SOME FOCUS AS THE
ATMOSPHERE DESTABILIZES THIS AFTERNOON. 00Z GFS RUN FROM LAST
EVENING SHOWED SURFACE BASED CAPES REACHING OVER 3000 J/KG OVER
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. INTERESTINGLY THOUGH THE
4 KM WRF RUN FROM 00Z DID NOT DEVELOP MUCH OVER OUR AREA THIS
AFTERNOON OR EVENING. THAT MODEL (4 KM WRF-NMM RUN FOR SPC) DID A
DECENT JOB THE PAST TWO NIGHTS. SO CONFIDENCE IN CONVECTION LATER
TODAY IS NOT OVERLY HIGH. DID GO WITH LOWER THUNDERSTORM CHANCES BY
LATE EVENING AND CONFINED CHANCES TO JUST THE FAR SOUTHEAST PART
OF THE FORECAST AREA AFTER MIDNIGHT TONIGHT.
THE NEXT MAIN THUNDERSTORM CHANCE WILL START FRIDAY AFTERNOON...BUT
SHOULD INCREASE DRAMATICALLY FRIDAY NIGHT FOR AT LEAST THE NORTHERN
2/3 OF THE AREA. KEPT LOW CHANCES GOING SATURDAY...BUT THINK STORM
CHANCES ARE HIGH SATURDAY EVENING INTO SATURDAY NIGHT. KEPT POPS AT
40-60 PERCENT AS A COLD FRONT PUSHES THROUGH. GENERALLY WENT WITH
FRONTAL TIMING DEPICTED BY THE GFS. GENERALLY LOWERED THUNDERSTORM
CHANCES AFTER TUESDAY AS LARGE SCALE PATTERN CHANGES SOMEWHAT.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
248 PM EDT THU MAY 3 2012
.SYNOPSIS...
STRONG UPPER LEVEL HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH
THE WEEK. A COLD FRONT WILL DROP SOUTH THROUGH THE AREA LATE
SATURDAY AND INTO SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 1045 AM THURSDAY...
HAVE BEEN MONITORING THE SOUTHWEST ADVANCEMENT OF A LOW STRATUS/FOG
SHIELD ACROSS SOUTHEAST AND SOUTHERN VIRGINIA INTO NORTHEAST NC.
THIS FEATURE HAD BEEN MAKING STEADY PROGRESS TO THE SOUTHWEST FOR
SEVERAL HOURS AND HAS REACHED HALIFAX AND WARREN COUNTIES. RECENT
SAT TRENDS SUGGEST THAT THE SW PUSH HAS SLOWED AND THE CLOUDS/FOG
MAY HAVE REACHED THEIR FURTHEST SOUTHWARD EXTENT. THIS FEATURE WAS
NOT WELL PROGGED BY THE NAM/GFS BUT RECENT RUNS OF THE RAHWRFARW AND
ESPECIALLY THE HRRR PICKED UP ON THIS FEATURE. EXPECT THE CLOUDS TO
HOLD FOR A FEW MORE HOURS WHERE THEY HAVE REACHED BUT NOT MOVE TOO
MUCH FURTHER SW.
THE 12Z KGSO RAOB PROVIDES A 1000-850 THICKNESS OF 1408M OR 4M
GREATER THAN 12Z WED. 850MB TEMPS WARMED 3DEG C FROM 12Z WED.
700MB HEIGHTS AT KGSO REACHED 3205M WHICH ALL SUPPORT VERY WARM
AFTERNOON HIGHS ABOUT 2 DEGREES WARMER THAN WED. THIS SHOULD RESULT
IN NEAR RECORD HIGHS OF 90-93 DEGREES TODAY.
THREAT OF CONVECTION TODAY IS RATHER LIMITED WITH THE LACK OF
FORCING MECHANISMS. ONE DISTURBANCE OVER SOUTHEAST VA WHICH SHOWS UP
WELL IN THE 1.5PV ANALYSIS SHOULD REMAIN NORTHEAST OF OUR AREA
THROUGH THE AFTERNOON. ANOTHER DISTURBANCE ELONGATED NORTH-SOUTH
ACROSS THE TN VALLEY WILL SHIFT TOWARD THE MOUNTAINS THIS EVENING.
THE BEST FORCING FOR ASCENT WITH THIS FEATURE SHOULD REMAIN ACROSS
THE MOUNTAINS. DIFFERENTIAL HEATING BOUNDARY ASSOCIATED WITH THE
PREVIOUSLY NOTED CLOUD SHIELD COULD ALSO FOCUS CONVECTION. WOULD NOT
BE SURPRISED TO SEE AN ISOLATED STORM MOVE FROM THE FOOTHILLS INTO
THE NORTHERN PIEDMONT OR OTHER ISOLATED ACTIVITY LATE THIS AFTERNOON
IN THE NORTHERN TIER BUT THE COVERAGE IS EXPECTED TO BE SO LIMITED
WE WILL OMIT POPS.
THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS WILL BRING A SLIGHT
REPRIEVE ON FRIDAY AND FRIDAY NIGHT WITH H7 HEIGHTS FALLING 60-70
METERS WITH H8 TEMPS COOLING OFF TO 15 TO 16C. ADDITIONALLY...AS
PLUME OF TROPICAL MOISTURE SURGES NORTHWARD INTO THE AREA(PWATS +2SD
ABOVE NORMAL...1.5-1.7")...EXPECT CLOUDY TO MOSTLY CLOUDY SKIES AND
THE PROSPECTS OF CONVECTION TO GREATLY LIMIT HEATING. WILL LOWER
FORECAST HIGHS INTO THE MID TO UPPER 80S...BUT COULD CONCEIVABLY BE
COOLER...MORE IN THE WAY IN THE LOWER TO MID 80S IF THE CONVECTION
MOVES/DEVELOPS EARLY ENOUGH. MILD OVERNIGHT LOWS GENERALLY IN THE
MID 60S.
WILL KEEP A DRY FORECAST FOR TONIGHT WITH BROAD ANTICYCLONIC FLOW
AND ASSOCIATED SUBSIDENCE THE RULE. RAIN CHANCES RETURN ON FRIDAY
WITH THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS MOVING THROUGH
THE AREA DURING PEAK AFTERNOON HEATING PROVIDING THE FOCUS FOR
SCATTERED SHOWERS AND THUNDERSTORM FRIDAY AFTERNOON AND INTO THE
EARLY EVENING BEFORE THE WAVE SHIFTS EAST OF THE AFTER MIDNIGHT.
WHILE MODELS SHOW MODERATE INSTABILITY ACROSS THE AREA FRIDAY
AFTERNOON...WIND SHEAR IS VERY WEAK...10 TO 15KTS. THUS DO NOT
EXPECT MUCH IN THE WAY OF SEVERE. HOWEVER...DUE TO HIGH
PWATS...LOCALLY HEAVY RAIN IS POSSIBLE.
BLAES/CBL
&&
.SHORT TERM /6 AM SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 220 PM...
SATURDAY FORECAST HINGES ON THE TIMING AND STRENGTH OF A FRONT
DROPPING SOUTH FROM VIRGINIA DURING THE DAY. THE MAJORITY OF
MODELS INDICATE A SURFACE FRONT NEAR THE VIRGINIA BORDER AT
SUNRISE... WITH THE NAM A FASTER OUTLIER. THE MAJORITY OF
SOLUTIONS HAVE THE FRONT NEAR HIGHWAY 64 BY EARLY AFTERNOON AND TO
THE FAYETTEVILLE VICINITY BY DARK. LOW LEVEL FLOW IS WEAK AHEAD OF
THE FRONT AND FROM THE WEST BY LATE FRIDAY NIGHT. CONVERGENCE
ALONG THE FRONT IS WEAK. HOWEVER INSTABILITY AND POTENTIAL ENERGY
IS AT LEAST MODERATE AND THERE IS AGREEMENT ON A SHORT WAVE
PASSAGE ALOFT WITH THE FRONT. ONLY WEAK LOW LEVEL FLOW PREVENTS
MOVING POPS TO LIKELY... AND WILL HOLD POPS AT 40 PERCENT. THE
SEVERE THREAT LOOKS SMALL BUT NONZERO.
TEMPERATURES FOR THE DAY WERE LOWERED... AND COULD YET BE TOO
HIGH... ESPECIALLY IN THE NORTH. HIGH TEMPERATURES IN THE MID 80S
WITH A FEW UPPER 80S SOUTH. MORE EXTENSIVE CLOUDS... PRECIPITATION
OR THE FASTER TIMING OF THE NAM COULD KNOCK TEN DEGREES OFF THESE
FORECAST TEMPERATURES.
LINGERING RAIN CHANCES IN THE SOUTH WITH THE FRONT SATURDAY EVENING.
PRECIPITATION WITH VORTICITY CENTERS ON THE MODELS UNRELIABLE AND
WILL PUT FAITH IN WEAK NORTH SURFACE FLOW AND LACK OF SURFACE
TRIGGERS TO LEAVE THE REST OF THE NIGHT DRY. LITTLE ADVECTION IN
THE WEAK NORTH FLOW... AND LOW TEMPERATURES IN THE LOW TO MID 60S.
NORTH FLOW SUNDAY SHIFTING TO EAST FOR THE EVENING AND SUNDAY NIGHT.
WILL KEEP THIS PERIOD DRY. SOME MARINE STRATUS LIKELY SATURDAY NIGHT
IN THE EAST FLOW... PERSISTING INTO THE AFTERNOON... THOUGH LIFTING.
HIGH TEMPERATURES UPPER 70S NORTHEAST TO MID 80S SUNDAY WITH LOW
TEMPERATURES UPPER 50S TO LOWER 60S.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 245 PM...
THE WEATHER IS LIKELY DRY INTO TUESDAY MORNING. SURFACE HIGH
PRESSURE MOVING INTO THE ATLANTIC WITH FLOW OVER CENTRAL NORTH
CAROLINA BECOMING SOUTHEAST... THEN SOUTH MONDAY NIGHT. MODELS IN
ROUGH AGREEMENT IN BRINGING A FRONT TO THE MOUNTAINS BEFORE SUNSET
TUESDAY. THE UPPER LEVEL SUPPORT OF A MINOR SHORT WAVE IN SOME OF
THE MODELS APPEARS TO ORIGINATE WITH CONVECTION IN THE MIDWEST
DURING THE WEEKEND AND COULD DISAPPEAR WITH LATER MODEL RUNS. LOW
CHANCE POPS IN THE NORTHWEST TUESDAY AFTERNOON... SPREADING EAST
OVERNIGHT. AN UPPER LEVEL WAVE MOVING THROUGH THE GREAT LAKES IS
SIGNIFICANTLY STRONGER... PUSHING THE FRONT THROUGH CENTRAL NORTH
CAROLINA WEDNESDAY INTO THE LATE EVENING. LIMITING POPS TO FORTY
PERCENT WITH AN EVENT THIS FAR OUT IN TIME. THE UPPER WAVE CLOSES
OFF AND LINGERS OVER NEW ENGLAND INTO THURSDAY NIGHT. WILL HAVE LATE
WEDNESDAY NIGHT INTO THURSDAY DRY IN NORTHWEST TO WEST FLOW.
HIGH TEMPERATURES MID 70S TO LOWER 80S AS LOW LEVEL THICKNESSES AT
GREENSBORO SETTLE IN NEAR CLIMATOLOGY. LOW TEMPERATURES UPPER 50S TO
LOWER 60S.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AS OF 140 PM THURSDAY...
WEAK HIGH PRESSURE AND A RIDGE ALOFT SHOULD RESULT IN MAINLY VFR
CONDITIONS THROUGH THE 24 HOUR TAF PERIOD. INCREASING CIRRUS TONIGHT
WILL LEAD TO SOME ALTOSTRATUS/ALTOCUMULUS LATE TONIGHT/FRIDAY.
LITTLE CUMULUS EXPECTED TODAY WITH SCT CUMULUS EXPECTED EARLY
FRIDAY AFTERNOON. LIGHT SOUTHWESTERLY WINDS AT 8KTS OR LESS WILL
BECOME MORE WESTERLY AND INCREASE TO AROUND 10 KTS ON FRIDAY.
LOOKING FURTHER AHEAD...
ISOLATED TO SCATTERED AFTERNOON AND EARLY EVENING SHOWERS AND
THUNDERSTORMS WILL BE THE MAIN CONCERN DURING THE EXTENDED RANGE
WITH THE BEST CHANCE OF CONVECTION ASSOCIATED WITH FRONTS THAT WILL
BE IN THE AREA ON SATURDAY AND WEDNESDAY. PATCHY PREDAWN FOG/STRATUS
WILL ALSO BE POSSIBLE EACH MORNING. -BLAES
&&
.CLIMATE...
THE FOLLOWING ARE RECORD HIGH TEMPERATURES FOR THE REMAINDER OF THE
WEEK:
RDU GSO FAY
THU MAY 3RD: 93 IN 1959 92 IN 1959 95 IN 1913
FRI MAY 4TH: 94 IN 1938 94 IN 1928 97 IN 1938
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
NEAR TERM...BLAES/CBL
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
225 PM EDT THU MAY 3 2012
.SYNOPSIS...
STRONG UPPER LEVEL HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH
THE WEEK. A COLD FRONT WILL DROP SOUTH THROUGH THE AREA LATE
SATURDAY AND INTO SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM THURSDAY...
HAVE BEEN MONITORING THE SOUTHWEST ADVANCEMENT OF A LOW STRATUS/FOG
SHIELD ACROSS SOUTHEAST AND SOUTHERN VIRGINIA INTO NORTHEAST NC.
THIS FEATURE HAD BEEN MAKING STEADY PROGRESS TO THE SOUTHWEST FOR
SEVERAL HOURS AND HAS REACHED HALIFAX AND WARREN COUNTIES. RECENT
SAT TRENDS SUGGEST THAT THE SW PUSH HAS SLOWED AND THE CLOUDS/FOG
MAY HAVE REACHED THEIR FURTHEST SOUTHWARD EXTENT. THIS FEATURE WAS
NOT WELL PROGGED BY THE NAM/GFS BUT RECENT RUNS OF THE RAHWRFARW AND
ESPECIALLY THE HRRR PICKED UP ON THIS FEATURE. EXPECT THE CLOUDS TO
HOLD FOR A FEW MORE HOURS WHERE THEY HAVE REACHED BUT NOT MOVE TOO
MUCH FURTHER SW.
THE 12Z KGSO RAOB PROVIDES A 1000-850 THICKNESS OF 1408M OR 4M
GREATER THAN 12Z WED. 850MB TEMPS WARMED 3DEG C FROM 12Z WED.
700MB HEIGHTS AT KGSO REACHED 3205M WHICH ALL SUPPORT VERY WARM
AFTERNOON HIGHS ABOUT 2 DEGREES WARMER THAN WED. THIS SHOULD RESULT
IN NEAR RECORD HIGHS OF 90-93 DEGREES TODAY.
THREAT OF CONVECTION TODAY IS RATHER LIMITED WITH THE LACK OF
FORCING MECHANISMS. ONE DISTURBANCE OVER SOUTHEAST VA WHICH SHOWS UP
WELL IN THE 1.5PV ANALYSIS SHOULD REMAIN NORTHEAST OF OUR AREA
THROUGH THE AFTERNOON. ANOTHER DISTURBANCE ELONGATED NORTH-SOUTH
ACROSS THE TN VALLEY WILL SHIFT TOWARD THE MOUNTAINS THIS EVENING.
THE BEST FORCING FOR ASCENT WITH THIS FEATURE SHOULD REMAIN ACROSS
THE MOUNTAINS. DIFFERENTIAL HEATING BOUNDARY ASSOCIATED WITH THE
PREVIOUSLY NOTED CLOUD SHIELD COULD ALSO FOCUS CONVECTION. WOULD NOT
BE SURPRISED TO SEE AN ISOLATED STORM MOVE FROM THE FOOTHILLS INTO
THE NORTHERN PIEDMONT OR OTHER ISOLATED ACTIVITY LATE THIS AFTERNOON
IN THE NORTHERN TIER BUT THE COVERAGE IS EXPECTED TO BE SO LIMITED
WE WILL OMIT POPS.
THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS WILL BRING A SLIGHT
REPRIEVE ON FRIDAY AND FRIDAY NIGHT WITH H7 HEIGHTS FALLING 60-70
METERS WITH H8 TEMPS COOLING OFF TO 15 TO 16C. ADDITIONALLY...AS
PLUME OF TROPICAL MOISTURE SURGES NORTHWARD INTO THE AREA(PWATS +2SD
ABOVE NORMAL...1.5-1.7")...EXPECT CLOUDY TO MOSTLY CLOUDY SKIES AND
THE PROSPECTS OF CONVECTION TO GREATLY LIMIT HEATING. WILL LOWER
FORECAST HIGHS INTO THE MID TO UPPER 80S...BUT COULD CONCEIVABLY BE
COOLER...MORE IN THE WAY IN THE LOWER TO MID 80S IF THE CONVECTION
MOVES/DEVELOPS EARLY ENOUGH. MILD OVERNIGHT LOWS GENERALLY IN THE
MID 60S.
WILL KEEP A DRY FORECAST FOR TONIGHT WITH BROAD ANTICYCLONIC FLOW
AND ASSOCIATED SUBSIDENCE THE RULE. RAIN CHANCES RETURN ON FRIDAY
WITH THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS MOVING THROUGH
THE AREA DURING PEAK AFTERNOON HEATING PROVIDING THE FOCUS FOR
SCATTERED SHOWERS AND THUNDERSTORM FRIDAY AFTERNOON AND INTO THE
EARLY EVENING BEFORE THE WAVE SHIFTS EAST OF THE AFTER MIDNIGHT.
WHILE MODELS SHOW MODERATE INSTABILITY ACROSS THE AREA FRIDAY
AFTERNOON...WIND SHEAR IS VERY WEAK...10 TO 15KTS. THUS DO NOT
EXPECT MUCH IN THE WAY OF SEVERE. HOWEVER...DUE TO HIGH
PWATS...LOCALLY HEAVY RAIN IS POSSIBLE.
BLAES/CBL
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 220 PM...
SATURDAY FORECAST HINGES ON THE TIMING AND STRENGTH OF A FRONT
DROPPING SOUTH FROM VIRGINIA DURING THE DAY. THE MAJORITY OF
MODELS INDICATE A SURFACE FRONT NEAR THE VIRGINIA BORDER AT
SUNRISE... WITH THE NAM A FASTER OUTLIER. THE MAJORITY OF
SOLUTIONS HAVE THE FRONT NEAR HIGHWAY 64 BY EARLY AFTERNOON AND TO
THE FAYETTEVILLE VICINITY BY DARK. LOW LEVEL FLOW IS WEAK AHEAD OF
THE FRONT AND FROM THE WEST BY LATE FRIDAY NIGHT. CONVERGENCE
ALONG THE FRONT IS WEAK. HOWEVER INSTABILITY AND POTENTIAL ENERGY
IS AT LEAST MODERATE AND THERE IS AGREEMENT ON A SHORT WAVE
PASSAGE ALOFT WITH THE FRONT. ONLY WEAK LOW LEVEL FLOW PREVENTS
MOVING POPS TO LIKELY... AND WILL HOLD POPS AT 40 PERCENT. THE
SEVERE THREAT LOOKS SMALL BUT NONZERO.
TEMPERATURES FOR THE DAY WERE LOWERED... AND COULD YET BE TOO
HIGH... ESPECIALLY IN THE NORTH. HIGH TEMPERATURES IN THE MID 80S
WITH A FEW UPPER 80S SOUTH. MORE EXTENSIVE CLOUDS... PRECIPITATION
OR THE FASTER TIMING OF THE NAM COULD KNOCK TEN DEGREES OFF THESE
FORECAST TEMPERATURES.
LINGERING RAIN CHANCES IN THE SOUTH WITH THE FRONT SATURDAY EVENING.
PRECIPITATION WITH VORTICITY CENTERS ON THE MODELS UNRELIABLE AND
WILL PUT FAITH IN WEAK NORTH SURFACE FLOW AND LACK OF SURFACE
TRIGGERS TO LEAVE THE REST OF THE NIGHT DRY. LITTLE ADVECTION IN
THE WEAK NORTH FLOW... AND LOW TEMPERATURES IN THE LOW TO MID 60S.
NORTH FLOW SUNDAY SHIFTING TO EAST FOR THE EVENING AND SUNDAY NIGHT.
WILL KEEP THIS PERIOD DRY. SOME MARINE STRATUS LIKELY SATURDAY NIGHT
IN THE EAST FLOW... PERSISTING INTO THE AFTERNOON... THOUGH LIFTING.
HIGH TEMPERATURES UPPER 70S NORTHEAST TO MID 80S SUNDAY WITH LOW
TEMPERATURES UPPER 50S TO LOWER 60S.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
THE BEGINNING OF THE LONG TERM PERIOD SHOULD START MOSTLY DRY...WITH
SEASONAL TEMPS AS HIGH PRESSURE CONTINUES TO RIDGE INTO THE AREA
FROM THE NORTH. THERE WILL BE A SLIGHT CHANCE OF DIURNAL CONVECTION
ON MONDAY...ESPECIALLY ACROSS THE SOUTHWESTERN/WESTERN PORTIONS OF
THE FORECAST AREA DUE TO PROXIMITY OF A STALLED FRONT. THEN THE
SURFACE HIGH RIDGING WILL SHIFT OFFSHORE BY TUESDAY AS THE NEXT
SYSTEM APPROACHES FROM THE NORTHWEST. PRECIP CHANCES WILL INCREASE
TUESDAY INTO THE WEDNESDAY AS THE FRONT SHIFTS BACK NORTH ACROSS THE
REGION AND WARM...MOIST SOUTHERLY FLOW RETURNS TO THE AREA. ALSO...
AS THE AFOREMENTIONED SURFACE LOW PRESSURE SYSTEM TRACKS TO THE
NORTH OF THE AREA...IT TRIES TO PUSH A COLD FRONT TOWARDS THE REGION
BY MID WEEK...WHICH MAY ALSO HELP TO INCREASE PRECIP CHANCES.
HOWEVER...AS CAN BE EXPECTED DURING THIS PART OF THE FORECAST...
THERE IS TIMING AND STRENGTH DIFFERENCES IN THE MODELS...THEREFORE
WILL GO NO HIGH THAN LOW END CHANCE POPS AT THIS TIME. TEMPS WILL
GRADUALLY WARM THROUGH THE PERIOD AS RETURN FLOW SETS UP OVER THE
REGION...BUT SHOULD STAY JUST ABOVE NORMAL VALUES...GENERALLY IN THE
LOW TO MID 80S BY WEDNESDAY.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AS OF 140 PM THURSDAY...
WEAK HIGH PRESSURE AND A RIDGE ALOFT SHOULD RESULT IN MAINLY VFR
CONDITIONS THROUGH THE 24 HOUR TAF PERIOD. INCREASING CIRRUS TONIGHT
WILL LEAD TO SOME ALTOSTRATUS/ALTOSTRATUS LATE TONIGHT/FRIDAY.
LITTLE CUMULUS EXPECTED TODAY WITH SCT CUMULUS EXPECTED EARLY FRIDAY
AFTERNOON. LIGHT SOUTHWESTERLY WINDS AT 8KTS OR LESS WILL BECOME
MORE WESTERLY AND INCREASE TO AROUND 10 KTS ON FRIDAY.
LOOKING FURTHER AHEAD...
ISOLATED TO SCATTERED AFTERNOON AND EARLY EVENING SHOWERS AND
THUNDERSTORMS WILL BE THE MAIN CONCERN DURING THE EXTENDED RANGE
WITH THE BEST CHANCE OF CONVECTION ASSOCIATED WITH FRONTS THAT WILL
BE IN THE AREA ON SATURDAY AND WEDNESDAY. PATCHY PREDAWN FOG/STRATUS
WILL ALSO BE POSSIBLE EACH MORNING. -BLAES
&&
.CLIMATE...
THE FOLLOWING ARE RECORD HIGH TEMPERATURES FOR THE REMAINDER OF THE
WEEK:
RDU GSO FAY
THU MAY 3RD: 93 IN 1959 92 IN 1959 95 IN 1913
FRI MAY 4TH: 94 IN 1938 94 IN 1928 97 IN 1938
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
NEAR TERM...BLAES/CBL
LONG TERM...KRR
AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
140 PM EDT THU MAY 3 2012
.SYNOPSIS...
STRONG UPPER LEVEL HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH
THE WEEK. A COLD FRONT WILL DROP SOUTH THROUGH THE AREA LATE
SATURDAY AND INTO SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM THURSDAY...
HAVE BEEN MONITORING THE SOUTHWEST ADVANCEMENT OF A LOW STRATUS/FOG
SHIELD ACROSS SOUTHEAST AND SOUTHERN VIRGINIA INTO NORTHEAST NC.
THIS FEATURE HAD BEEN MAKING STEADY PROGRESS TO THE SOUTHWEST FOR
SEVERAL HOURS AND HAS REACHED HALIFAX AND WARREN COUNTIES. RECENT
SAT TRENDS SUGGEST THAT THE SW PUSH HAS SLOWED AND THE CLOUDS/FOG
MAY HAVE REACHED THEIR FURTHEST SOUTHWARD EXTENT. THIS FEATURE WAS
NOT WELL PROGGED BY THE NAM/GFS BUT RECENT RUNS OF THE RAHWRFARW AND
ESPECIALLY THE HRRR PICKED UP ON THIS FEATURE. EXPECT THE CLOUDS TO
HOLD FOR A FEW MORE HOURS WHERE THEY HAVE REACHED BUT NOT MOVE TOO
MUCH FURTHER SW.
THE 12Z KGSO RAOB PROVIDES A 1000-850 THICKNESS OF 1408M OR 4M
GREATER THAN 12Z WED. 850MB TEMPS WARMED 3DEG C FROM 12Z WED.
700MB HEIGHTS AT KGSO REACHED 3205M WHICH ALL SUPPORT VERY WARM
AFTERNOON HIGHS ABOUT 2 DEGREES WARMER THAN WED. THIS SHOULD RESULT
IN NEAR RECORD HIGHS OF 90-93 DEGREES TODAY.
THREAT OF CONVECTION TODAY IS RATHER LIMITED WITH THE LACK OF
FORCING MECHANISMS. ONE DISTURBANCE OVER SOUTHEAST VA WHICH SHOWS UP
WELL IN THE 1.5PV ANALYSIS SHOULD REMAIN NORTHEAST OF OUR AREA
THROUGH THE AFTERNOON. ANOTHER DISTURBANCE ELONGATED NORTH-SOUTH
ACROSS THE TN VALLEY WILL SHIFT TOWARD THE MOUNTAINS THIS EVENING.
THE BEST FORCING FOR ASCENT WITH THIS FEATURE SHOULD REMAIN ACROSS
THE MOUNTAINS. DIFFERENTIAL HEATING BOUNDARY ASSOCIATED WITH THE
PREVIOUSLY NOTED CLOUD SHIELD COULD ALSO FOCUS CONVECTION. WOULD NOT
BE SURPRISED TO SEE AN ISOLATED STORM MOVE FROM THE FOOTHILLS INTO
THE NORTHERN PIEDMONT OR OTHER ISOLATED ACTIVITY LATE THIS AFTERNOON
IN THE NORTHERN TIER BUT THE COVERAGE IS EXPECTED TO BE SO LIMITED
WE WILL OMIT POPS.
THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS WILL BRING A SLIGHT
REPRIEVE ON FRIDAY AND FRIDAY NIGHT WITH H7 HEIGHTS FALLING 60-70
METERS WITH H8 TEMPS COOLING OFF TO 15 TO 16C. ADDITIONALLY...AS
PLUME OF TROPICAL MOISTURE SURGES NORTHWARD INTO THE AREA(PWATS +2SD
ABOVE NORMAL...1.5-1.7")...EXPECT CLOUDY TO MOSTLY CLOUDY SKIES AND
THE PROSPECTS OF CONVECTION TO GREATLY LIMIT HEATING. WILL LOWER
FORECAST HIGHS INTO THE MID TO UPPER 80S...BUT COULD CONCEIVABLY BE
COOLER...MORE IN THE WAY IN THE LOWER TO MID 80S IF THE CONVECTION
MOVES/DEVELOPS EARLY ENOUGH. MILD OVERNIGHT LOWS GENERALLY IN THE
MID 60S.
WILL KEEP A DRY FORECAST FOR TONIGHT WITH BROAD ANTICYCLONIC FLOW
AND ASSOCIATED SUBSIDENCE THE RULE. RAIN CHANCES RETURN ON FRIDAY
WITH THE PASSAGE OF THE MID-UPPER LEVEL SHEAR AXIS MOVING THROUGH
THE AREA DURING PEAK AFTERNOON HEATING PROVIDING THE FOCUS FOR
SCATTERED SHOWERS AND THUNDERSTORM FRIDAY AFTERNOON AND INTO THE
EARLY EVENING BEFORE THE WAVE SHIFTS EAST OF THE AFTER MIDNIGHT.
WHILE MODELS SHOW MODERATE INSTABILITY ACROSS THE AREA FRIDAY
AFTERNOON...WIND SHEAR IS VERY WEAK...10 TO 15KTS. THUS DO NOT
EXPECT MUCH IN THE WAY OF SEVERE. HOWEVER...DUE TO HIGH
PWATS...LOCALLY HEAVY RAIN IS POSSIBLE.
BLAES/CBL
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM THURSDAY...
A SURFACE LOW OVER NEW ENGLAND WILL GRADUALLY SHIFT SOUTHEAST
SATURDAY INTO SUNDAY...BRINGING A COLD FRONT AND ASSOCIATED PRECIP
CHANCES TOWARDS THE REGION. MODELS HAVE COME INTO A LITTLE BETTER
AGREEMENT WITH THEIR HANDLING OF THIS FRONT OVER THE AREA FOR THE
WEEKEND. AT THIS TIME...IT APPEARS THE FRONT SHOULD CROSS THE AREA
LATE SATURDAY INTO SUNDAY AND THEN STALL NEAR THE SOUTHWESTERN
PORTIONS OF THE FORECAST AREA BY LATE SUNDAY...WITH HIGH PRESSURE
BUILDING IN FROM THE NORTH. THEREFORE...PRECIP CHANCES SHOULD
INCREASE THROUGH THE DAY ON SATURDAY...BEFORE DECREASING FROM
NORTHEAST TO SOUTHWEST LATE SUNDAY. WE SHOULD SEE ONE MORE DAY OF
HIGHS IN THE UPPER 80S TO NEAR 90 DEGREES ON SATURDAY...BEFORE
SLIGHTLY COOLER MAX TEMPS ON SUNDAY BEHIND THE FRONT...GENERALLY LOW
TO MID 80S. SIMILAR TREND IS EXPECTED FOR OVERNIGHT LOWS...WITH
GENERALLY MID 60S EXPECTED SATURDAY NIGHT AND UPPER 50S TO LOWER 60S
EXPECTED BY SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...
THE BEGINNING OF THE LONG TERM PERIOD SHOULD START MOSTLY DRY...WITH
SEASONAL TEMPS AS HIGH PRESSURE CONTINUES TO RIDGE INTO THE AREA
FROM THE NORTH. THERE WILL BE A SLIGHT CHANCE OF DIURNAL CONVECTION
ON MONDAY...ESPECIALLY ACROSS THE SOUTHWESTERN/WESTERN PORTIONS OF
THE FORECAST AREA DUE TO PROXIMITY OF A STALLED FRONT. THEN THE
SURFACE HIGH RIDGING WILL SHIFT OFFSHORE BY TUESDAY AS THE NEXT
SYSTEM APPROACHES FROM THE NORTHWEST. PRECIP CHANCES WILL INCREASE
TUESDAY INTO THE WEDNESDAY AS THE FRONT SHIFTS BACK NORTH ACROSS THE
REGION AND WARM...MOIST SOUTHERLY FLOW RETURNS TO THE AREA. ALSO...
AS THE AFOREMENTIONED SURFACE LOW PRESSURE SYSTEM TRACKS TO THE
NORTH OF THE AREA...IT TRIES TO PUSH A COLD FRONT TOWARDS THE REGION
BY MID WEEK...WHICH MAY ALSO HELP TO INCREASE PRECIP CHANCES.
HOWEVER...AS CAN BE EXPECTED DURING THIS PART OF THE FORECAST...
THERE IS TIMING AND STRENGTH DIFFERENCES IN THE MODELS...THEREFORE
WILL GO NO HIGH THAN LOW END CHANCE POPS AT THIS TIME. TEMPS WILL
GRADUALLY WARM THROUGH THE PERIOD AS RETURN FLOW SETS UP OVER THE
REGION...BUT SHOULD STAY JUST ABOVE NORMAL VALUES...GENERALLY IN THE
LOW TO MID 80S BY WEDNESDAY.
&&
.AVIATION /18Z THURSDAY THROUGH MONDAY/...
AS OF 140 PM THURSDAY...
WEAK HIGH PRESSURE AND A RIDGE ALOFT SHOULD RESULT IN MAINLY VFR
CONDITIONS THROUGH THE 24 HOUR TAF PERIOD. INCREASING CIRRUS TONIGHT
WILL LEAD TO SOME ALTOSTRATUS/ALTOSTRATUS LATE TONIGHT/FRIDAY.
LITTLE CUMULUS EXPECTED TODAY WITH SCT CUMULUS EXPECTED EARLY FRIDAY
AFTERNOON. LIGHT SOUTHWESTERLY WINDS AT 8KTS OR LESS WILL BECOME
MORE WESTERLY AND INCREASE TO AROUND 10 KTS ON FRIDAY.
LOOKING FURTHER AHEAD...
ISOLATED TO SCATTERED AFTERNOON AND EARLY EVENING SHOWERS AND
THUNDERSTORMS WILL BE THE MAIN CONCERN DURING THE EXTENDED RANGE
WITH THE BEST CHANCE OF CONVECTION ASSOCIATED WITH FRONTS THAT WILL
BE IN THE AREA ON SATURDAY AND WEDNESDAY. PATCHY PREDAWN FOG/STRATUS
WILL ALSO BE POSSIBLE EACH MORNING. -BLAES
&&
.CLIMATE...
THE FOLLOWING ARE RECORD HIGH TEMPERATURES FOR THE REMAINDER OF THE
WEEK:
RDU GSO FAY
THU MAY 3RD: 93 IN 1959 92 IN 1959 95 IN 1913
FRI MAY 4TH: 94 IN 1938 94 IN 1928 97 IN 1938
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...BLAES/CBL
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...BLAES
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
138 PM EDT THU MAY 3 2012
.SYNOPSIS...
A FRONT JUST NORTH OF LAKE ERIE WILL REMAIN NEARLY STATIONARY INTO
FRIDAY AS WAVES OF LOW PRESSURE MOVE ALONG THE FRONT. THE FRONT WILL
DROP SOUTHEAST ACROSS THE AREA LATER FRIDAY AND STALL NEAR THE OHIO
RIVER UNTIL A LOW SLOWLY MOVES ACROSS OHIO MONDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...BOOSTED TEMPS A BIT IN PLACES BASED ON LATEST HRRR OUTPUT.
FOR 630 AM UPDATE...ONLY CHANGE WILL BE TO LOWER POPS FOR MORNING
SINCE NOTHING OF NOTE CURRENTLY OCCURRING. ALSO WILL ADD SOME PATCHY
FOG FOR NEXT FEW HOURS.
THE AIRMASS WILL REMAIN UNSTABLE TODAY. A LOW LEVEL JET WILL
CONTINUE TO BRING MOISTURE INTO THE CWA FROM THE SW WHILE WIND SHEAR
REMAINS RELATIVELY WEAK. THE SHORT TERM HI RES MODELS SEEM TO WANT
TO PRODUCE THE MOST CONVECTION INTO THE MORNING THEN THE NAM AND GFS
TAPER BACK THE THREAT INTO THE AFTERNOON AS THE FRONTAL CONVERGENCE
LIFTS NE OF THE AREA. WILL CONTINUE CHANCE POPS FOR TODAY WITH THE
BEST CHANCE IN THE NORTH. DUE TO THE LIMITED RISK FOR SEVERE WILL
NOT MENTION AT THIS TIME.
A VERY WARM DAY IS IN STORE WITH RECORD OR NEAR RECORD HIGHS
POSSIBLE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
THE WEAK FRONTAL BOUNDARY WILL GET PUSHED SOUTH ACROSS THE CWA FRI.
ABUNDANT MOISTURE PRESENT WITH PW`S AROUND 1.5 INCHES. EXPECT FAIRLY
WIDESPREAD SHRA/TSRA TO SPREAD SE ACROSS THE REGION WITH THE FRONT.
CLOUD COVER WILL BE MORE EXTENSIVE SO THIS SHOULD HELP TO LIMIT HIGH
TEMPS/INSTABILITY AND THUS THE SEVERE THREAT.
FRI NIGHT...THE BETTER THREAT FOR CONVECTION SHOULD BE SHIFTING INTO
THE SOUTHERN HALF OF THE CWA WITH A LINGERING CHANCE INTO SAT FOR
MAINLY THE SOUTH. EVEN THOUGH OVERALL AIRMASS REMAINS QUITE WARM ON
SAT...NE FLOW OFF OF A CHILLY LAKE ERIE WILL LIKELY KEEP TEMPS IN
THE LOW TO MID 60S DOWNWIND OF THE LAKE.
THE HIGH TO THE NORTH SHOULD PUSH ENOUGH OF A RIDGE SOUTH INTO THE
AREA TO HOLD OFF THE PRECIP THREAT FOR SAT NIGHT AND SUN BUT
OVERRUNNING IN THE SW WILL BEGIN ON SUN AND COULD ALLOW SOME
CONVECTION TO RETURN.
THE APPROACH OF A LOW WEST OF THE AREA BY DAYBREAK MON WILL PROBABLY
LEAD TO MORE CONVECTION PUSHING INTO AT LEAST THE WEST HALF OF THE
AREA SUN NIGHT.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE WILL BE MOVING INTO THE REGION ON MONDAY WITH INCREASED
CHANCES OF RAIN BY AFTERNOON. THIS RAIN WILL CONTINUE INTO MONDAY
NIGHT AND MAY ACTUALLY LINGER INTO TUESDAY MORNING. MODELS ARE
DIFFERING ON HOW FAST THIS LOW WILL CLEAR THE AREA. A FRONTAL
BOUNDARY WILL NOT BE ALL THAT FAR FROM THE SOUTHERN COUNTY WARNING
AREA ON TUESDAY NIGHT BUT IT APPEARS THAT MUCH OF THE AREA WILL BE
DRY. MODELS ARE STRUGGLING ON HOW TO DIG THE NEXT TROUGH INTO THE
CENTRAL LAKES ON WEDNESDAY. THE DIFFERING SCENARIOS WOULD BE SHOWERS
RETURNING EITHER EARLY WEDNESDAY OR MAYBE HOLDING OFF UNTIL
AFTERNOON OR EVENING.
HIGHS WILL LIKELY BE ABOVE AVERAGE ON MONDAY BUT WE WILL COOL BACK
TO SEASONAL LEVELS FOR TUESDAY INTO WEDNESDAY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
SITES DOMINATED BY HIGH PRESSURE AND SOUTHERLY FLOW THIS
AFTERNOON. SOME THUNDERSTORM DEVELOPMENT IS EXPECTED TO CONTINUE
ACROSS NE OH AND NW PA ALONG LAKE BREEZE BOUNDARY. HOWEVER...WITH
ERI NORTH OF THE BOUNDARY WITH ONSHORE FLOW EXPECTING STORMS TO
PASS JUST SOUTH OF THE FIELD SO DIDN/T INCLUDE VCTS. WILL WATCH
THIS AREA THOUGH IF STORMS DO COME CLOSER TO THE AIRPORT.
ELSEWHERE EXPECTING SOUTHWEST FLOW THROUGH THE AFTERNOON WITH VFR
CONDITIONS AND SCT-BKN CLOUDS AROUND 040-070. COLD FRONT EXPECTED
TO DROP SOUTH INTO NW OH IMPACTING TOL FIRST FRI MORNING. HAVE
SOME SHRA MENTIONED THERE. SITES FURTHER EAST WILL SEE SHRA/TS
NEAR OR AFTER 18Z FRI.
.OUTLOOK...NON-VFR CONDITIONS POSSIBLE IN CONVECTION FRIDAY
AFTERNOON/EVENING. NON-VFR POSSIBLE ON MONDAY.
&&
.MARINE...
WARM FRONT WILL BE IN THE VICINITY OF THE NORTH SHORE OF LAKE ERIE
TODAY. THIS SHOULD ALLOW FOR A SOUTH TO SOUTHWEST WIND ACROSS THE
ENTIRE LAKE. THE STRONGEST WINDS WILL LIKELY BE ACROSS THE WESTERN
BASIN BUT SHOULD NOT EXCEED 20 KNOTS. SOUTHWESTERLY WINDS WILL
CONTINUE INTO FRIDAY NIGHT WITH A WIND SHIFT EXPECTED BY SATURDAY
MORNING AS A COLD FRONT PASSES. HIGH PRESSURE IN THE WAKE OF THE
FRONT WILL REMAIN IN CONTROL INTO SUNDAY WITH NORTHEAST TO EAST
WINDS EXPECTED. THIS WILL LIKELY CAUSE WAVES TO BUILD BUT WITH WINDS
NOT EXPECTED TO BE HIGHER THAN 15 KNOTS WE SHOULD SEE 2 TO 4 FOOT
WAVES. WE WILL HAVE TO WATCH THE WESTERN HALF OF THE LAKE CLOSELY IF
WIND SPEEDS ARE A BIT STRONGER THAN ANTICIPATED. AS LOW PRESSURE
APPROACHES THE CENTRAL LAKES ON MONDAY WINDS SHOULD GRADUALLY SWING
AROUND TO THE SOUTH.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...ADAMS/TK
SHORT TERM...ADAMS
LONG TERM...MULLEN
AVIATION...ABE
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
250 PM CDT THU MAY 3 2012
.SHORT TERM...TONIGHT AND FRIDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW MULTIPLE AREAS
OF LOW PRESSURE RANGING FROM THE UPPER PENINSULA TO CENTRAL KANSAS
EARLY THIS AFTERNOON. ATTACHED TO ONE OF THE LOWS OVER SOUTHERN
MINNESOTA IS A WARM FRONT WHICH HAS MOVED VERY LITTLE FROM MSP TO
MTW. EARLIER MCV HAS DEPARTED THE REGION WHILE WE AWAIT FOR ANOTHER
SMALLER CLUSTER OF STORMS TO PUSH INTO CENTRAL WISCONSIN. IN
GENERAL...THE WIDESPREAD CONVECTION FROM EARLIER TODAY AS WORKED
OVER THE ATMOSPHERE...WHILE CLOUD COVER HAS PREVENTED FULL
SURFACE-BASED HEATING. BETTER HEATING HAS OCCURRED OVER SOUTHERN
WISCONSIN WHERE TEMPS HAVE WARMED INTO THE UPPER 70S TO LOWER 80S.
WILL HAVE TO REACH INTO THE MID TO UPPER 70S FOR A CHANCE OF
ADDITIONAL STORM DEVELOPMENT THROUGH THE REST OF THE AFTERNOON.
WITH ADDITIONAL SHOWERS AND STORMS PUSHING IN FROM THE WEST AND
AMPLE CLOUD COVER OVERHEAD...THINK CHANCES OF THIS OCCURRING IS
FAIRLY LOW. MEANWHILE...A COLD FRONT IS DROPPING SOUTH ACROSS LAKE
SUPERIOR AND NORTHERN MINNESOTA WHERE TEMPS FALL BACK INTO THE 50S.
THE MAIN FORECAST CONCERNS INCLUDE THUNDER AND SEVERE WEATHER
CHANCES TONIGHT.
TONIGHT...THE PESKY SURFACE WARM FRONT WILL CONTINUED TO BE DRAPED
ACROSS CENTRAL WISCONSIN EARLY IN THE EVENING. MODEL GUIDANCE SHOWS
THE RIGHT REAR QUAD OF A JET STREAK BUILDING BACK INTO SOUTHERN AND
CENTRAL WISCONSIN THROUGH THE EVENING. AS A RESULT...THERE IS
ENOUGH SUPPORT ALOFT TO KEEP A HIGH CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FORECAST FROM CENTRAL TO NORTHEAST WISCONSIN.
THE LLJ WILL BE DEVELOPING WELL SOUTH AND EAST OF THE REGION...SO
WILL NOT HAVE THE GOOD MASS CONVERGENCE FOR SEVERE STORMS...BUT
PERHAPS ENOUGH FOR ISOLATED TO SCT COVERAGE. A COLD FRONT WILL DROP
INTO NORTHERN WISCONSIN IN THE EVENING...THEN DRIVE INTO CENTRAL
WISCONSIN OVERNIGHT. THIS FRONT WILL END THE SHOWER AND
THUNDERSTORM THREAT...AS WELL AS BRING A RETURN OF NORTHEAST WINDS
AND LESS HUMID CONDITIONS. QUITE A BIT OF LOW STRATO-CU UPSTREAM
BEHIND THE FRONT...AND THINK WILL HAVE A PROBLEM CLEARING ESPECIALLY
WITH THE AMPLE LOW LEVEL MOISTURE LEFT BEHIND FROM THE EXCESSIVE
RAINFALL. LOWS BACK INTO THE 40S NORTH TO THE UPPER 50S SOUTH.
FRIDAY...SURFACE COLD FRONT WILL MOVE FROM CENTRAL WISCONSIN INTO
NORTHERN ILLINOIS AND NORTHEAST IOWA IN THE AFTERNOON. BEHIND THE
FRONT...CANADIAN HIGH PRESSURE WILL BUILD SOUTH ACROSS THE STATE
THROUGH THE DAY. WILL SEE COOLER AND NOTICEABLY DRIER CONDITIONS
ARRIVE...BROUGHT IN BY BRISK NE WINDS. LOOKING UPSTREAM...PLENTY OF
LOW CLOUDS BEHIND THE FRONT OVER SOUTHERN MANITOBA AND ONTARIO...SO
THINK WILL SEE A MOSTLY CLOUDY MORNING...FOLLOWED BY PARTLY SUNNY
CONDITIONS IN THE AFTERNOON. NEXT SYSTEM LOOKS LIKE IT WILL STAY TO
THE WEST AT THIS POINT. HIGHS IN THE 50S NEAR LAKE MICHIGAN...TO
AROUND 70 OVER CENTRAL WISCONSIN.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY.
MAIN CONCERN FOR THIS PACKAGE WILL BE THE PERIODIC CHANCES FOR
SHOWERS OR THUNDERSTORMS INTO EARLY NEXT WEEK. SOME MODEL DIFFERENCES
NOTED IN TIMING OF THESE SYSTEMS. FIRST SYSTEM EXPECTED TO PUSH
INTO THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL HAVE A SMALL
CHANCE OF SHOWERS ACROSS THE WEST LATE FRIDAY NIGHT...THEN A
CHANCE ACROSS THE ENTIRE AREA SATURDAY. DRY AIR FROM A CANADIAN
HIGH PRESSURE SHOULD LIMIT THE THUNDER POTENTIAL. DID KEEP ISOLATED
THUNDER ACROSS THE FAR WEST AND SOUTH TO MATCH UP WITH LA CROSSE
AND MILWAUKEE.
FOR SATURDAY NIGHT...THERE MAY BE A LINGERING SHOWER SATURDAY
EVENING...THEN THERE WILL BE A CHANCE OF SHOWERS AGAIN LATE
SATURDAY NIGHT ACROSS THE FAR WEST. STRONGER SYSTEM WORKING ACROSS
THE AREA WILL BRING LIKELY CHANCES FOR SHOWERS AND THUNDERSTORMS
SUNDAY INTO SUNDAY NIGHT. WILL CONTINUE TO KEEP A SMALL CHANCES OF
SHOWERS DUE TO DEPARTING SYSTEM...THEN MONDAY NIGHT SHOULD BE MAINLY
DRY.
AN UPPER TROUGH IS THEN EXPECTED TO SWING ACROSS THE AREA TUESDAY
AFTERNOON AND TUESDAY NIGHT...BRINGING ANOTHER CHANCE FOR SHOWERS
AND ISOLATED THUNDERSTORMS. FOR WEDNESDAY...CYCLONIC FLOW WILL GRADUALLY
PUSH EAST. WILL CONTINUE THE SMALL CHANCE FOR SHOWERS. HIGH PRESSURE
THEN BUILDS INTO THE REGION FOR WEDNESDAY NIGHT AND THURSDAY. TEMPERATURES
WILL RUN AT OR BELOW NORMAL DURING THE PERIOD.
&&
.AVIATION...FORECAST UNCERTAINTY IS SPILLING OVER INTO THE TAF
DEPARTMENT. ISOLATED TO SCATTERED SHOWERS AND STORMS REMAIN
POSSIBLE THROUGH EARLY THIS EVENING ACROSS NORTH-CENTRAL AND
NORTHEAST WISCONSIN. STRONGEST STORMS MAY IMPACT THE FOX VALLEY IF
TEMPERATURES CAN WARM INTO THE MIDDLE TO UPPER 70S.
OTHERWISE...PARTIAL CLEARING THIS AFTERNOON WILL LEAD TO VFR
CONDITIONS OUTSIDE OF THUNDERSTORMS. A COLD FRONT WILL PASS ACROSS
THE AREA FROM NORTH TO SOUTH TONIGHT. AMPLE MOISTURE FROM THE
RAINFALL AND THE ARRIVAL OF COOLER AIR WILL LEAD TO THE POSSIBILITY
OF LOWERING MVFR CIGS TO POSSIBLY IFR LATE TONIGHT. CLOUDS TO STICK
AROUND IN THE MORNING...THOUGH CIGS WILL BE IMPROVING AS A RESULT OF
DAYTIME HEATING.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/ECKBERG
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1229 PM CDT THU MAY 3 2012
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.UPDATE...LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A
BROAD AREA OF LOW PRESSURE CENTERED OVER SOUTHERN MINNESOTA AND
NORTHERN IOWA...WITH A WARM FRONT EXTENDING ACROSS CENTRAL
WISCONSIN TO AROUND MANITOWOC. AN MCV IS TRACKING ALONG THE WARM
FRONT OVER CENTRAL WISCONSIN...WHICH HAS IGNITED ANOTHER ROUND OF
SHOWERS AND THUNDERSTORMS. WITH CLOUD TOPS COOLING...POTENTIAL
WILL REMAIN FOR AN ISOLATED SEVERE WEATHER THREAT UNTIL ABOUT
MIDDAY...WHEN THE MCV DEPARTS. HAVE HAD WIND GUSTS UP TO 40 KTS
AND NICKEL SIZED HAIL WITH THE STORMS PROGRESSING ACROSS EAST-
CENTRAL WISCONSIN SO FAR.
WITH THE WARM FRONT EXTENDING BACK TOWARDS MINNEAPOLIS WHERE
ANOTHER NEAR SEVERE CLUSTER OF STORMS EXISTS...POTENTIAL WILL BE
THERE FOR SCATTERED THUNDERSTORM ACTIVITY THROUGH THE AFTERNOON.
THOUGH DID PLACE THE HIGHEST POPS OVER NE WISCONSIN WITHIN THE
COMMA HEAD OF THE MCV THAT WILL BE DEPARTING EARLY THIS AFTERNOON.
AS FOR THE SEVERE THREAT...THE ATMOSPHERE HAS BEEN WORKED OVER
CONTINUOUSLY SINCE THE OVERNIGHT HOURS...AND WILL NEED TO SEE SOME
HEATING IN ORDER TO GET A SURFACE BASED THREAT. CONFIDENCE IS LOW
THAT THIS WILL OCCUR...DO TO THE ONGOING CONVECTION...AND CLOUD
COVER UPSTREAM. WOULD THINK OUTFLOW BOUNDARIES SOUTH OF THE
CONVECTION OVER SOUTHERN WISCONSIN WOULD STAND A BETTER CHANCE.
WILL KEEP AN EYE ON IT...AND WILL SEE IF THE CLUSTER NEAR MSP CAN
STAY ALIVE INTO CENTRAL WISCONSIN LATER THIS AFTERNOON.
MPC
&&
.PREV DISCUSSION...ISSUED AT 339 AM CDT THU MAY 3 2012...
SYNOPSIS...WARM AND HUMID WITH SHOWERS AND THUNDERSTORMS
TODAY...THEN TURNING COOLER AND LESS HUMID.
BROAD UPR TROF PRESENTLY COVERS THE WRN 3/4 OF THE CONUS...WITH
RIDGING OVER THE FAR E. DEVELOPING BLOCKING PATTERN OVER FAR ERN
CANADA AND THE NW ATL WL FORCE ERN CONUS RIDGE TO REFORM WEST OVER
THE GREAT LAKES RGN DURING THE WEEKEND...THEN THE REMNANTS OF THE
WRN TROF WL PROGRESS EWD ACRS THE RGN DURING THE EARLY TO MIDDLE
PART OF NEXT WK.
HAVING THE UPR PATTERN IN A STATE OF FLUX WL RESULT IN A VARIETY
OF WX ACRS THE FCST AREA. WARM AND WET PATTERN WL PREVAIL EARLY...
WITH FLOODING NOW ONGOING ACRS THE FAR SRN PART OF THE FCST AREA.
A SWD SURGE OF COOLER CANADIAN AIR WL PUSH THE BULK OF THE PCPN S
AND ALLOW COOLER AIR TO DOMINATE FOR A DAY OR TWO. THEN CHCS FOR
PCPN WL RETURN AS REMNANTS OF THE WRN TROF HEAD TOWARD THE AREA.
PCPN AMNTS FOR THE 7 DAY PERIOD SHOULD END UP ABV NORMAL.
TEMPS WL START OUT ABV NORMAL THEN FALL BACK CLOSER TO NORMAL.
SHORT TERM...TDA/TNGT/FRI. MAIN CONCERN IS ONGOING FLASH
FLOODING ACRS THE FAR SRN PART OF THE FCST AREA. LINE OF
CONVECTION PRODUCING THE FLOODING WAS BEING FED BY SWLY LLJ OF
40-45 KTS... WHICH WAS FEEDING INSTABILITY IN FM THE SW. MESO
PLOTS THE LAST COUPLE HRS SHOWED THE STRONGEST LOW-LEVEL MOISTURE
CONVERGENCE STARTING TO SHIFT OFF TO THE E IN RESPONSE TO GRADUAL
VEERING OF THE LLJ. SO THINK THE AMNT OF BACKBUILDING AND TRAINING
INTO THE FLOOD ZONE WL DECR. SCHEDULED 10Z/11Z EXPIRATION TIMES OF
THE WARNINGS MIGHT BE CUTTING IT CLOSE...ESP SINCE FLOODING WL
LINGER EVEN AFTER RAIN DIMINISHES. WL NEED TO RE-EVALUATE THAT AS
WE GET CLOSE TO THE EXPIRATION TIMES.
PCPN TRENDS LATER TDA NOT VERY CLEAR CUT. GIVEN MID-LVL SHRTWV
HEADED INTO THE AREA...POSN OF FCST AREA NR RRQ OF UPR JET...AND
COLD FRONT SET TO SAG INTO THE N THIS AFTN...ADDITIONAL TSRA
DEVELOPMENT SEEMS A GOOD BET. BUT SUSPECT IT WON/T BE QUITE AS
FOCUSED/ORGAINZED AS CURRENT BATCH. WL CARRY FAIRLY HIGH
POPS...BUT DON/T FEEL MUCH IN THE WAY OF SPECIFICS/DETAILS CAN BE
ADDED AT THIS POINT. SPC SLGT RISK COVERS ABOUT THE SRN 1/2 OF THE
FCST AREA. ALTHOUGH A SVR STORM CAN/T BE RULED OUT...RIGHT NOW
THERE WOULD SEEM TO BE TOO MANY CLDS AND NOT ENOUGH FOCUSED
FORCING FOR MORE THAN A MARGINAL SVR EVENT.
FRONT WL CONT TO SAG SWD TNGT. SLOWLY EDGED POPS SWD DURING THE
NIGHT...DRYING OUT THE N AFTER MIDNIGHT. LINGERED LOW POPS OVER
THE FAR S EARLY FRI...AND BROUGHT LOW POPS BACK INTO THE FAR NW
LATE IN THE DAY. ADJUSTED TEMPS DOWN AS INCRG NELY FLOW WILL BRING
COOLER AND DRIER AIR INTO THE RGN...AND ACRS THE COLD WATERS OF
THE GREAT LAKES.
LONG TERM...FRI NGT THRU NXT WED. MAIN FCST FOCUS TO BE THE
MOVEMENT OF AN EWD MOVING...POSITIVELY-TILTED UPR TROF WHICH
EVENTUALLY SPLITS INTO A SW CONUS CUT-OFF UPR LOW AND NEARLY
CUT-OFF UPR LOW OVER THE GREAT LKS. INITIALLY...STILL DEALING
WITH ACTIVE W-SW FLOW THRU THE WEEKEND WITH SMALL PCPN CHCS AND
THEN INSTABILITY PCPN TOWARD MID-WEEK WITH THE UPR LOW. TEMPS ARE
EXPECTED TO AVERAGE BLO NORMAL THRU THE MIDDLE OF NXT WEEK.
MDLS ARE STILL AT ODDS WITH THE TIMING OF THE NXT PROMINENT
SHORTWAVE TOPPING THE RELATIVELY FLAT UPR RDG SITUATED OVER THE
CNTRL CONUS. LATEST THINKING IS FOR BETTER PCPN CHCS TO ARRIVE
LATER FRI NGT (AFTER MIDNGT) AND FOCUSED MORE TOWARD CNTRL WI.
HAVE ADDED MORE CLOUDS TOWARD CNTRL WI AND KEPT POPS IN THE CHC
CATEGORY. FARTHER EAST...ENUF DRY AIR MAY KEEP MOST OF THE PCPN AT
BAY FOR MOST OF THE NGT SO HAVE KEPT POPS THERE AT A MINIMUM.
THIS SHORTWAVE PULLS AWAY FROM THE AREA BY SAT MORNING LEAVING AN
EASTERLY FLOW OVER NE WI AND WAITING FOR THE NXT SHORTWAVE TO
APPROACH. IT APPEARS THAT THERE IS A GAP LARGE ENUF SUCH THAT ANY
PCPN CHCS COULD HOLD OFF TIL AFTER SUNSET. SINCE THERE IS NO
TRIGGER EVIDENT AT THE SFC OR ALOFT...MAY BE ABLE TO GET BY MOST
OF THE DAY WITHOUT SEEING MEASURABLE PCPN. STILL EXPECT TO SEE
ENUF CLOUDS AROUND TO KEEP TEMPS IN CHECK WITH READINGS RANGING
FROM THE UPPER 50S LAKESIDE TO THE MIDDLE 60S OVER THE WARMER
SPOTS OF CNTRL WI.
HI PRES DROPPING SE INTO ERN ONTARIO WL CONT TO FUNNEL DRY AIR
INTO NE WI SAT NGT WHILE THE NEARLY CLOSED UPR LOW MOVES TOWARD
ND/SRN MANITOBA. THE NXT SHORTWAVE IS FCST TO RIDE INTO THE UPR MS
VALLEY...BUT AGAIN MDLS DISAGREE ON ITS LOCATION. THIS BRINGS A
SIGNIFICANT TIMING ISSUE TO WHEN TO BRING THE NXT CHC OF SHWRS/
TSTMS TO THE FCST AREA. ONCE AGAIN...IT WOULD SEEM CNTRL WI WOULD
HAVE THE BETTER CHC OF SEEING MEASURABLE PCPN AS THE EAST IS
SOMEWHAT PROTECTED BY THE DRY EASTERLY WINDS. THE HI PRES BEGINS
TO LOSE ITS INFLUENCE OVER ERN WI ON SUNDAY AS THE NEARLY
VERTICALLY STACKED LOW PRES SYSTEM SPINS OVER SRN MANITOBA.
SOMEWHAT OF A BLOCKING PATTERN ALOFT WL SLOW THE ADVANCEMENT OF
BOTH THE SHORTWAVE ALOFT...AS WELL AS A CDFNT THRU THE UPR MS
VALLEY. THEREFORE...WL NEED TO CARRY A HIGHER CHC POP ACROSS CNTRL
WI (CLOSER TO THE SHORTWAVE/CDFNT) WITH ENUF INSTABILITY TO
GENERATE ISOLATED TSTMS. IT IS CONCEIVABLE THAT FAR ERN WI MAY
REMAIN MOSTLY DRY THRU SUNDAY.
THE CDFNT IS PROGGED TO PUSH ACROSS WI SUNDAY NGT AND BRING A GOOD
CHC OF SHWRS/TSTMS TO ALL OF NE WI. COOLER AIR WL SWEEP ACROSS THE
STATE BEHIND THE FNT WITH 8H TEMPS DROPPING INTO THE SINGLE DIGITS
BY MIDDAY MON. MEANWHILE...THE AREA OF LOW PRES SOUTH OF LK
WINNIPEG MAY EASE ITS WAY EWD INTO SW ONTARIO. SOME SHWR ACTIVITY
MAY LINGER INTO MON MORNING PRIMARILY OVER THE EAST...HOWEVER A
DRYING TREND DOES SEEM TO BE AGREED UPON BY THE MDLS FORO THE REST
OF MON. TEMPS WL DROP TO BLO NORMAL LEVELS WITH MAX TEMPS ON MON IN
THE UPR 50S TO LWR 60S.
MDLS EVENTUALLY BRING THIS WEAKENING LOW PRES SYSTEM (SHORTWAVE
TROF ALOFT/WEAK SFC LOW) TOWARD/INTO THE GREAT LKS REGION NXT TUE
AND WED. DAYTIME HEATING COUPLED WITH A COLD POOL ALOFT WL
INCREASE INSTABILITY TO BRING A CHC OF SHWRS/TSTMS TO NE WI
PRIMARILY DURING THE AFTERNOON HOURS.
&&
.AVIATION...FORECAST UNCERTAINTY IS SPILLING OVER INTO THE TAF
DEPARTMENT. ISOLATED TO SCATTERED SHOWERS AND STORMS REMAIN
POSSIBLE THROUGH EARLY THIS EVENING ACROSS NORTH-CENTRAL AND
NORTHEAST WISCONSIN. STRONGEST STORMS MAY IMPACT THE FOX VALLEY IF
TEMPERATURES CAN WARM INTO THE MIDDLE TO UPPER 70S.
OTHERWISE...PARTIAL CLEARING THIS AFTERNOON WILL LEAD TO VFR
CONDITIONS OUTSIDE OF THUNDERSTORMS. A COLD FRONT WILL PASS ACROSS
THE AREA FROM NORTH TO SOUTH TONIGHT. AMPLE MOISTURE FROM THE
RAINFALL AND THE ARRIVAL OF COOLER AIR WILL LEAD TO THE POSSIBILITY
OF LOWERING MVFR CIGS TO POSSIBLY IFR LATE TONIGHT. CLOUDS TO STICK
AROUND IN THE MORNING...THOUGH CIGS WILL BE IMPROVING AS A RESULT OF
DAYTIME HEATING.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1138 AM CDT THU MAY 3 2012
.AVIATION/18Z TAFS/...MAIN CHALLENGE IS RESOLVING CONVECTIVE
TRENDS FOR TAF SITES. DECENT SSW FLOW INTO SRN WI WITH POTENTIAL
INTERACTION WITH OUTFLOW FROM STORMS TO OUR NORTH MAY HELP TO
REGENERATE MORE STORMS AS THE AFTERNOON/EVENING WEARS ALONG. WILL
HAVE CEILINGS PREVAILING AT VFR LEVELS. ONCE SYNOPTIC FRONT PASSES
SOUTH OF THE AREA EARLY FRIDAY...EXPECT WINDS TO SHARPLY SHIFT
NORTHEAST WITH BUFKIT SOUNDINGS SHOWING A GOOD DEAL OF STRATUS
WITH STRONG INVERSION
PC
&&
.MARINE...DECENT MIXING WITH THINNING IN CIRRUS CANOPY HAS ALLOWED
SMALL CRAFT TYPE WINDS TO MIX DOWN. PROBABLY NOT AFFECTING ALL OF
THE AREA DUE TO LIMITED MIXING FURTHER OFFSHORE...BUT WILL PUT OUT
A SHORT DURATION SMALL CRAFT TO COVER THE SITUATION.
PC
&&
.PREV DISCUSSION... /ISSUED 417 AM CDT THU MAY 3 2012/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
TRAINING MULTICELLULAR TSTORMS IS SLOWLY DECREASING IN COVERAGE AND
INTENSITY OVER THE FAR NRN CWA AND SHOULD BE CLOSE TO ENDING BY
SUNRISE OR SHORTLY AFTER AS THE LOW LEVEL JET STREAM FOCUSES MORE TO
THE NORTHEAST. A WEAK MCS OVER IA IS PROGRESSING TOWARD SRN WI
WITHIN THE MEAN FLOW WITH THE HRRR MODEL BRINGING IT ACROSS THE CWA
FROM 14Z TO 19Z. WENT WITH THIS SCENARIO. AFTERWARD BELIEVE THE MAIN
FOCUS FOR CONVECTION WILL BE TOWARD THE IL BORDER AND SWD DUE TO THE
STABILIZING EFFECTS OF THE CONVECTION...AND ALSO WITH THE MAIN FOCUS
OF THE LLJ AND ANY WEAK SHORTWAVE TROUGHS TO OUR SOUTH. THUS ONLY
HAVE CHANCE POPS FOR LATE AFTERNOON THROUGH TNT.
A GOOD PORTION OF MQT...GREEN LAKE COUNTIES HAVE RECEIVED
APPROXIMATELY 3-4 INCHES OF RAIN BUT ONLY MINOR FLOODING HAS BEEN
REPORTED DUE TO THE MANY AREAS OF MARSHES AND LAKES ACTING AS A
SINK. THIS AREA WILL STILL BE MORE SUSCEPTIBLE TO FLOODING BUT
CONFIDENCE FOR FLASH FLOODING IS TOO LOW TO ISSUE A WATCH AND
BELIEVE THIS AREA CAN HANDLE ANOTHER INCH OR LESS OF RAIN WITHOUT
FLASH FLOODING OCCURRING.
FRIDAY...FORECAST CONFIDENCE...MEDIUM
SURFACE FRONT EXPECTED TO GENERALLY BE NEAR THE WI/IL BORDER FRIDAY
MORNING...THOUGH THERE ARE MODEL DIFFERENCES AND THURSDAY NIGHT
CONVECTION WILL PROBABLY HAVE A SAY ON THE LOCATION OF THE
BOUNDARY BY MORNING. KEPT SOME POPS GOING THROUGH THE DAY
FRIDAY...THE BEST CHANCE SOUTH TOWARD THE FRONT. NAM AND GFS
SUPPORT POPS MORE THAN THE ECMWF AND CANADIAN...WITH THE FRONT
FARTHER NORTH THAN THE LATTER MODELS. THE NAM AND GFS WOULD ALSO
BE WARMER...THOUGH TEMPS SEEM A BIT OVERDONE GIVEN SFC FEATURES.
SIZABLE TEMP DIFFERENCES BETWEEN THE TWO SOLUTIONS...SO GENERALLY
SPLIT THE DIFFERENCE. WILL BE COOLER TOWARD THE LAKE UNDER
NORTHEAST WINDS.
SATURDAY THOUGH MONDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
MODELS GENERALLY KEEP THE BAROCLINIC ZONE IN THE AREA FOR SATURDAY
AND SUNDAY...PUSHING LOW PRESSURE THOUGH SUNDAY NIGHT INTO MONDAY.
FELT THE NEED TO KEEP POPS GOING THROUGH THE WEEKEND WITH A COUPLE
IMPULSES RIDING THROUGH THE FLOW. BEST CHANCE FOR PRECIP WILL BE
SUNDAY NIGHT AND MONDAY AS THE LOW SLIDES THOUGH. MODEL SOUNDINGS
CONTINUE TO SHOW SOME CAPE THROUGH MONDAY...SO KEPT THUNDER
MENTION WITH PRECIP. MODELS CONTINUE TO BOUNCE AROUND A BIT WITH
TEMPS FOR THE WEEKEND AND MONDAY...AS THE BAROCLINIC ZONE SHIFTS
SOME FROM RUN TO RUN. THUS GENERALLY WENT WITH CONSENSUS OF MODEL
TEMPS...RESULTING IN NEAR NORMAL VALUES. WILL BE COOLER NEAR LAKE
MICHIGAN WITH PERSISTENT ONSHORE FLOW.
TUESDAY AND WEDNESDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
UPPER TROUGH TO APPROACH TUESDAY...MOVING THROUGH TUESDAY NIGHT OR
WEDNESDAY. THUS MORE SHOWER CHANCES EXPECTED...WITH MAYBE A FEW
RUMBLES OF THUNDER. NEAR NORMAL TEMPS ANTICIPATED TO CONTINUE
THROUGH THE FIRST HALF OF THE WEEK.
AVIATION/12Z TAFS/...MAINLY VFR CONDITIONS ARE EXPECTED TODAY AND
TONIGHT BUT THUNDERSTORMS ARE LIKELY FROM LATE THIS MORNING INTO THE
EARLY AFTERNOON WITH THE POTENTIAL FOR THUNDERSTORMS TO CONTINUE
TONIGHT. MVFR TO IFR CONDITIONS WILL OCCUR WITHIN THE THUNDERSTORMS
AND MAY LINGER IN THEIR WAKE AS WELL.
MARINE...WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA BUT MOIST AIR FLOWING OVER THE COLD WATERS OF LAKE MICHIGAN
MAY RESULT IN FOG...AT TIMES DENSE...FOR TODAY AND TONIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR LMZ645-
646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
FRIDAY THROUGH WEDNESDAY...DDV