Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/20/13

AREA FORECAST DISCUSSION

NWS DENVER/BOULDER CO

 827 PM MDT THU SEP 19 2013

.UPDATE...ENOUGH DRY AIR ALOFT HAS PUSHED ACROSS THE FORECAST AREA
TO BRING AN END TO THE LINGERING SHOWERS/SPRINKLES. THERE WAS A
HIGH STRATUS DECK AGAINST THE FOOTHILLS/PALMER DIVIDE...BUT NOT
SHOWING TOO MUCH GROWTH AT THE CURRENT TIME. OTHERWISE CLEAR TO
PARTLY CLOUDY SKIES PREVAIL LENDING TOWARD A CRISP AUTUMN-LIKE
NIGHT WITH LOWS DROPPING INTO THE 40S ON THE PLAINS AND UPPER
20S/30S MOUNTAINS. CURRENT FORECAST ON TRACK WITH ONLY MINOR
ADJUSTMENTS.

&&

.AVIATION...NO SIGNIFICANT CHANGES WITH STILL A THREAT OF
4500-6000 FT CEILINGS THROUGH ABOUT 11Z-13Z. OTHERWISE VISUAL
LANDING CONDITIONS WILL PREVAIL.

&&

.HYDROLOGY...NO ADDITIONAL PRECIPITATION EXPECTED TONIGHT. SOUTH
PLATTE RIVER NEAR WELDONA HAS FALLEN BELOW FLOOD STAGE...SO THAT
SECTION HAS BEEN CANCELLED FROM THE FLOOD WARNING. STILL SOME
MINOR FLOODING REPORTED IN CENTRAL WELD COUNTY AROUND KERSEY SO
WILL KEEP WARNING THERE FOR NOW. FARTHER DOWNSTREAM FROM AROUND
FORT MORGAN TO THE NEBRASKA STATE LINE RIVER LEVELS ARE RECEDING
SLIGHTLY BUT IT WILL TAKE A COUPLE MORE DAYS BEFORE FLOODING
ENDS.

&&

.PREV DISCUSSION... /ISSUED 320 PM MDT THU SEP 19 2013/

SHORT TERM...AREA OF ELONGATED MID LEVEL POTENTIAL VORTICITY
EXTENDING FROM FAR NORTHEAST COLORADO SOUTHWEST ACROSS THE PLAINS
INTO THE SOUTHERN FOOTHILLS AND PARK COUNTY HEADING EAST. THIS
FEATURE HELPED DEVELOP ISOLATED RAIN SHOWERS...WITH A FEW
THUNDERSTORMS OVER SOUTH PARK AND SOUTHERN FOOTHILLS. RAINFALL HAD
BEEN LIGHT...LESS THAN A TENTH OF AN INCH. THIS ACTIVITY WAS
SHIFTING EAST WITH THE POTENTIAL VORTICITY. LATEST SATELLITE
SHOWING A DECENT BACK EDGE OF THE MOISTURE WITH DRIER AIR MOVING
SOUTH. MODELS SHOW THIS FEATURE CONTINUING TO SHIFT EAST INTO THE
EVENING...WITH THE LATEST HRRR AND RAP SHOWING ALL THE
PRECIPITATION EAST OF THE AREA BY MIDNIGHT. THIS SEEMS REASONABLE
BASED ON THE CURRENT TRENDS. WILL KEEP A SLIGHT CHANCE OF STORMS
ACROSS PARK COUNTY AND SOUTHERN FOOTHILLS AND PALMER DIVIDE THIS
EVENING. THE NAM SEEMS A BIT SLOWER IN SHIFTING THE PRECIPITATION
EASTWARD...WILL LEAN TOWARD THE HRRR AND RAP SOLUTIONS. AFTER
MIDNIGHT...LOW LEVEL SOUTHEAST WINDS COULD BRING SOME LOW LEVEL
MOISTURE BACK INTO THE FOOTHILLS. THIS SHOWN BY FORECAST
SOUNDINGS. WILL INCREASE CLOUD COVER A BIT...ESPECIALLY ACROSS
LINCOLN COUNTY. OVERNIGHT TEMPERATURES TO COOL INTO THE 40S ACROSS
NORTHEAST COLORADO WITH MOUNTAIN VALLEYS NEAR OR BELOW FREEZING.
ON FRIDAY...UPPER RIDGE OVER GREAT BASIN SHIFTS EAST WITH THE AXIS
ALONG THE COLORADO WESTERN BORDER. NORTHWEST FLOW ALOFT WILL
CONTINUE TO SPREAD DRIER AND MORE SUBSIDENT AIR ACROSS THE THE
AREA. CLOUDS SHOULD DECREASE DURING THE MORNING WITH MAINLY SUNNY
CONDITIONS BY THE AFTERNOON. TEMPERATURES ACROSS THE PLAINS TO
WARM INTO THE LOWER AND MIDDLE 70S.

LONG TERM...A PAIR OF WEATHER SYSTEMS WILL MOVE ACROSS THE
STATE...ONE ON SUNDAY AND ANOTHER LATE NEXT WEEK. IN THE
MEANTIME...DRY AND SEASONABLE TEMPERATURES WILL PREVAIL. THE GFS
AND ECMWF MODELS ARE IN GOOD AGREEMENT AS THESE WELL DEFINED
TROUGHS TRAVERSE ACROSS THE WESTERN UNITED STATES. SATURDAY WILL
BE WARM AND SUNNY WHILE SUNDAY WILL BE A TRANSITION AHEAD OF THE
APPROACHING SYSTEM. PRECIPITATION SHOULD SPREAD INTO THE MOUNTAINS
BY SUNDAY AFTERNOON AND THEN MOVE ACROSS THE PLAINS SUNDAY NIGHT.
TEMPERATURES COULD DROP COLD ENOUGH FOR A CHANCE OF SNOW ABOVE
11000 FEET AS THE SYSTEM MOVES THROUGH. BEYOND SUNDAY...A RETURN
TO WESTERLY FLOW ALOFT WILL BRING WARM TEMPERATURES AND DRY
WEATHER BACK TO THE FORECAST AREA. NEXT FRIDAY MAY BE THE NEXT
TIME THE FORECAST AREA SEES ANY PRECIPITATION. AT THIS TIME...THE
SYSTEM LOOKS A BIT STRONGER THAN THE FIRST SYSTEM OVER THIS
WEEKEND.

AVIATION...NORTHEAST TO EAST WINDS TO SHIFT TO THE SOUTHEAST BY
00Z AS SURFACE HIGH MOVE SOUTH ACROSS THE EASTERN PLAINS. MODELS
CONTINUE TO SHOW SOME LOW LEVEL MOISTURE SPREADING NORTH AFTER
06Z. CEILINGS OF 4000 TO 6000 FEET AGL STILL EXPECTED TO DEVELOP
BETWEEN 07Z AND 13Z. SOUTHEAST SURFACE WINDS TO CONTINUE THROUGH
THE DAY FRIDAY AS DRIER AIR SPREADS OVER THE AREA. SHOULD SEE
CEILINGS IMPROVE AFTER 13Z.

HYDROLOGY...LINGERING SHOWERS AND A FEW THUNDERSTORMS ACROSS
SOUTH PARK AND SOUTHERN FOOTHILLS WILL COME TO AN END AROUND
MIDNIGHT AS DRIER AIR MOVES INTO THE REGION. ANY RAINFALL AMOUNTS
WILL BE LIGHT. NO SHOWERS OR STORMS EXPECTED FRIDAY.

RIVER LEVELS HAVE FLATTENED AND WILL GRADUALLY RECEDE OVER THE
NEXT FEW DAYS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
FLOOD WARNING SOUTH PLATTE RIVER THROUGH CENTRAL WELD COUNTY...AND
FROM NEAR FORT MORGAN TO THE NEBRASKA STATE LINE.

&&

$$

SHORT TERM...BARJENBRUCH
LONG TERM....DANKERS
AVIATION...BARJENBRUCH




AREA FORECAST DISCUSSION

NWS MIAMI FL

 811 PM EDT THU SEP 19 2013

.UPDATE...
SCATTERED MODERATE RAIN SHOWERS ALONG WITH A FEW EMBEDDED
THUNDERSTORMS CONTINUE TO PUSH ONSHORE THE EAST COAST ALONG MAINLY
BROWARD AND PALM-BEACH COUNTIES THIS EVENING UNDER NORTHEAST FLOW.
SHORT TERM GUIDANCE GRADUALLY DISSIPATES THESE SHOWERS AS THEY
CONTINUE TO PUSH TO THE SOUTHWEST APPROACHING THE INTERIOR. MORE
ORGANIZED CONVECTION JUST NOW EXITING THE SOUTHERN MOST GULF
MARINE ZONE WILL CONTINUE TO PUSH SOUTH TOWARD THE FLORIDA KEYS.
KEPT POPS ON A GRADUAL DOWNWARD TREND ACROSS THE AREA THROUGH THE
NIGHT.

&&

.PREV DISCUSSION... /ISSUED 709 PM EDT THU SEP 19 2013/

AVIATION...
ISOLATED SHOWERS ARE EXPECTED TO MOSTLY DISSIPATE BY 0Z...SO RAIN-
FREE TAFS AT ALL SITES THROUGH 0Z SAT. ISOLATED SHOWERS POSSIBLE
ANYTIME...ESPECIALLY MIDDAY FRIDAY...BUT EXPECTED COVERAGE AND
CONFIDENCE IS FAR TO LOW TO WARRANT INCLUSION OF VCSH ATTM. VFR
CONDITIONS PREVAIL. NE WINDS 5-10 KTS OVERNIGHT WILL INCREASE TO
10-15 KTS ON FRIDAY.

PREV DISCUSSION... /ISSUED 227 PM EDT THU SEP 19 2013/

SHORT TERM (TONIGHT-SATURDAY NIGHT)...
THIS EVENING...THE LATEST RADAR SCAN SHOWED SCATTERED ACTIVITY
DEVELOPING OVER THE INTERIOR AREAS SPREADING WESTWARD TOWARD THE
GULF COAST. THE LATEST HRRR MODEL RUNS LINE UP WELL WITH THIS AND
INDICATE THIS ACTIVITY BECOMING FOCUSED OVER AND AROUND THE GULF
COAST AREAS THROUGH THE LATE AFTERNOON AND EVENING HOURS ONCE AGAIN.
CONSIDERING THE EXTENSIVE RAINFALL COVERAGE OVER THE GULF COAST
YESTERDAY...THE MAIN CONCERN THROUGH THIS EVENING WILL BE THE
POTENTIAL FOR ADDITIONAL HEAVY RAINFALL AND FLOODING DUE TO THE
SATURATED GROUNDS.

FRIDAY THROUGH SATURDAY NIGHT...THE LATEST NUMERICAL GUIDANCE
REMAINS IN DECENT AGREEMENT THROUGH THIS PERIOD AND SHOWS WHAT IS
LEFT OF THE WEAKENING BOUNDARY OR TROUGH CURRENTLY MOVING INTO
THE AREA CONTINUING SOUTH WITH SOME DRIER AIR FILLING IN BEHIND IT
FROM THE NORTH. THIS COMBINED WITH THE MEAN LOW-LEVEL FLOW UP TO
10 KFT SHIFTING TO THE NORTH WILL TRANSLATE TO LOWER RAINFALL
CHANCES EACH DAY. DEWPOINTS COULD REACH THE LOWER 60S ACROSS
PORTIONS OF THE INTERIOR AREAS SATURDAY AFTERNOON. MODEL SOUNDINGS
INDICATE PRECIPITABLE WATER VALUES DIPPING DOWN TO AROUND 1.3"
ACROSS PORTIONS OF THE AREA BY SATURDAY. TEMPERATURES ARE FORECAST
TO REMAIN AROUND NORMAL THROUGH THIS PERIOD...WITH THE EXCEPTION
BEING THE POSSIBILITY OF REACHING THE UPPER 60S ACROSS THE
NORTHERN INTERIOR AREAS BY DAYBREAK SATURDAY MORNING.

LONG TERM (SUNDAY-WEDNESDAY)...
AN UPPER TROUGH IS FORECAST TO DIG ACROSS THE SOUTHEAST AND
EASTERN SEABOARD THROUGH THE SECOND HALF OF THE WEEKEND. OUT AHEAD
OF THIS...SURFACE AND LOW LEVEL FLOW WILL SHIFT TO THE
SOUTH...BRINGING A SURGE OF MOISTURE BACK INTO SOUTH FLORIDA ON
SUNDAY. MODELS HAVE BEEN TRENDING TOWARDS A WEAKER LOW LEVEL/SURFACE
REFLECTION ACROSS THE SOUTHEAST...AND THUS A WEAKER COLD FRONT
MOVING INTO THE SOUTHEAST STATES. THE ECMWF IS NOW STRONGER THAN THE
GFS WITH THE BAROCLINIC SURFACE LOW ACROSS THE NORTHERN GULF
COAST/SOUTHEAST STATES...AND DRAWS THE MOISTURE FROM THE BAY OF
CAMPECHE SYSTEM TO THE NORTHEAST. REGARDLESS...SINCE THE MODELS HAVE
TRENDED SLOWER WITH THE COLD FRONT AND KEEP IT ACROSS NORTH FLORIDA
THROUGH EARLY NEXT WEEK...THE FOCUS FOR STORMS MAY BE ACROSS THE
GULF WATERS AND NORTH OR CENTRAL FLORIDA. WITH NO FOCUS FOR RAINFALL
ACROSS SOUTH FLORIDA AND EXTENSIVE CLOUD COVER POSSIBLY LIMITING
RAINFALL AMOUNTS DURING THE DAY MONDAY AND TUESDAY...THE HEAVIEST
RAINS MAY ACTUALLY FALL OVER THE NIGHT TIME HOURS AS SPEED/COASTAL
CONVERGENCE SETS UP. THE GFS AND ECMWF ARE HINTING AT THIS AS
WELL. SO RAINFALL CHANCES WILL LIKELY REMAIN HIGH SUNDAY THROUGH
TUESDAY. THE FORECAST IS UNCLEAR BEYOND THAT POINT...BUT RAINFALL
CHANCES WILL REMAIN ELEVATED THROUGH AT LEAST WEDNESDAY.

MARINE...
LIGHT TO MODERATE NORTHEAST WINDS WILL CONTINUE THROUGH SATURDAY AS
A WEAKENING FRONTAL BOUNDARY SHIFTS SOUTH INTO THE AREA. WINDS WILL
SHIFT TO THE SOUTH THROUGH THE SECOND HALF OF THE WEEKEND AND INTO
EARLY NEXT WEEK AS ANOTHER FRONTAL BOUNDARY APPROACHES FROM THE
NORTH. SEAS OVER THE ATLANTIC WATERS SHOULD BEGIN TO SUBSIDE OVER
THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  75  88  74  88 / 30 20 10 10
FORT LAUDERDALE  76  88  77  89 / 30 20 10 10
MIAMI            76  89  75  89 / 30 20 10 10
NAPLES           73  90  73  90 / 30 20 10 20

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&

$$

DISCUSSION/MARINE/FIRE...10/CD
AVIATION/RADAR...23/SK






AREA FORECAST DISCUSSION

NWS MIAMI FL

 709 PM EDT THU SEP 19 2013

.AVIATION...
ISOLATED SHOWERS ARE EXPECTED TO MOSTLY DISSIPATE BY 0Z...SO RAIN-
FREE TAFS AT ALL SITES THROUGH 0Z SAT. ISOLATED SHOWERS POSSIBLE
ANYTIME...ESPECIALLY MIDDAY FRIDAY...BUT EXPECTED COVERAGE AND
CONFIDENCE IS FAR TO LOW TO WARRANT INCLUSION OF VCSH ATTM. VFR
CONDITIONS PREVAIL. NE WINDS 5-10 KTS OVERNIGHT WILL INCREASE TO
10-15 KTS ON FRIDAY.

&&

.PREV DISCUSSION... /ISSUED 227 PM EDT THU SEP 19 2013/

SHORT TERM (TONIGHT-SATURDAY NIGHT)...
THIS EVENING...THE LATEST RADAR SCAN SHOWED SCATTERED ACTIVITY
DEVELOPING OVER THE INTERIOR AREAS SPREADING WESTWARD TOWARD THE
GULF COAST. THE LATEST HRRR MODEL RUNS LINE UP WELL WITH THIS AND
INDICATE THIS ACTIVITY BECOMING FOCUSED OVER AND AROUND THE GULF
COAST AREAS THROUGH THE LATE AFTERNOON AND EVENING HOURS ONCE AGAIN.
CONSIDERING THE EXTENSIVE RAINFALL COVERAGE OVER THE GULF COAST
YESTERDAY...THE MAIN CONCERN THROUGH THIS EVENING WILL BE THE
POTENTIAL FOR ADDITIONAL HEAVY RAINFALL AND FLOODING DUE TO THE
SATURATED GROUNDS.

FRIDAY THROUGH SATURDAY NIGHT...THE LATEST NUMERICAL GUIDANCE
REMAINS IN DECENT AGREEMENT THROUGH THIS PERIOD AND SHOWS WHAT IS
LEFT OF THE WEAKENING BOUNDARY OR TROUGH CURRENTLY MOVING INTO
THE AREA CONTINUING SOUTH WITH SOME DRIER AIR FILLING IN BEHIND IT
FROM THE NORTH. THIS COMBINED WITH THE MEAN LOW-LEVEL FLOW UP TO
10 KFT SHIFTING TO THE NORTH WILL TRANSLATE TO LOWER RAINFALL
CHANCES EACH DAY. DEWPOINTS COULD REACH THE LOWER 60S ACROSS
PORTIONS OF THE INTERIOR AREAS SATURDAY AFTERNOON. MODEL SOUNDINGS
INDICATE PRECIPITABLE WATER VALUES DIPPING DOWN TO AROUND 1.3"
ACROSS PORTIONS OF THE AREA BY SATURDAY. TEMPERATURES ARE FORECAST
TO REMAIN AROUND NORMAL THROUGH THIS PERIOD...WITH THE EXCEPTION
BEING THE POSSIBILITY OF REACHING THE UPPER 60S ACROSS THE
NORTHERN INTERIOR AREAS BY DAYBREAK SATURDAY MORNING.

LONG TERM (SUNDAY-WEDNESDAY)...
AN UPPER TROUGH IS FORECAST TO DIG ACROSS THE SOUTHEAST AND
EASTERN SEABOARD THROUGH THE SECOND HALF OF THE WEEKEND. OUT AHEAD
OF THIS...SURFACE AND LOW LEVEL FLOW WILL SHIFT TO THE
SOUTH...BRINGING A SURGE OF MOISTURE BACK INTO SOUTH FLORIDA ON
SUNDAY. MODELS HAVE BEEN TRENDING TOWARDS A WEAKER LOW LEVEL/SURFACE
REFLECTION ACROSS THE SOUTHEAST...AND THUS A WEAKER COLD FRONT
MOVING INTO THE SOUTHEAST STATES. THE ECMWF IS NOW STRONGER THAN THE
GFS WITH THE BAROCLINIC SURFACE LOW ACROSS THE NORTHERN GULF
COAST/SOUTHEAST STATES...AND DRAWS THE MOISTURE FROM THE BAY OF
CAMPECHE SYSTEM TO THE NORTHEAST. REGARDLESS...SINCE THE MODELS HAVE
TRENDED SLOWER WITH THE COLD FRONT AND KEEP IT ACROSS NORTH FLORIDA
THROUGH EARLY NEXT WEEK...THE FOCUS FOR STORMS MAY BE ACROSS THE
GULF WATERS AND NORTH OR CENTRAL FLORIDA. WITH NO FOCUS FOR RAINFALL
ACROSS SOUTH FLORIDA AND EXTENSIVE CLOUD COVER POSSIBLY LIMITING
RAINFALL AMOUNTS DURING THE DAY MONDAY AND TUESDAY...THE HEAVIEST
RAINS MAY ACTUALLY FALL OVER THE NIGHT TIME HOURS AS SPEED/COASTAL
CONVERGENCE SETS UP. THE GFS AND ECMWF ARE HINTING AT THIS AS
WELL. SO RAINFALL CHANCES WILL LIKELY REMAIN HIGH SUNDAY THROUGH
TUESDAY. THE FORECAST IS UNCLEAR BEYOND THAT POINT...BUT RAINFALL
CHANCES WILL REMAIN ELEVATED THROUGH AT LEAST WEDNESDAY.

MARINE...
LIGHT TO MODERATE NORTHEAST WINDS WILL CONTINUE THROUGH SATURDAY AS
A WEAKENING FRONTAL BOUNDARY SHIFTS SOUTH INTO THE AREA. WINDS WILL
SHIFT TO THE SOUTH THROUGH THE SECOND HALF OF THE WEEKEND AND INTO
EARLY NEXT WEEK AS ANOTHER FRONTAL BOUNDARY APPROACHES FROM THE
NORTH. SEAS OVER THE ATLANTIC WATERS SHOULD BEGIN TO SUBSIDE OVER
THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  75  88  74  88 / 20 20 10 10
FORT LAUDERDALE  76  88  77  89 / 20 20 10 10
MIAMI            76  89  75  89 / 20 20 10 10
NAPLES           73  90  73  90 / 30 20 10 20

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&

$$

DISCUSSION/MARINE/FIRE...10/CD
AVIATION/RADAR...23/SK






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 1005 PM CDT THU SEP 19 2013

.MESOSCALE DISCUSSION...821 PM CDT

RADAR AND SATELLITE IMAGERY INDICATE THAT THE BOW ECHO OVER EASTERN
IOWA THAT HAD BEEN PLOWING EAST TOWARD THE CWA HAS BEGUN TO QUICKLY
SHRIVEL UP...MOST LIKELY DUE TO OUTRUNNING THE BETTER SHEAR AND
ENCOUNTERING INCREASING SURFACE BASE CONVECTIVE INHIBITION WITH
RATHER QUICK TEMP DROP OFF THAT OCCURRED AT SUNSET. SHOWERS AND
THUNDERSTORMS STILL EXPECTED TO MOVE ACROSS THE AREA OVERNIGHT INTO
EARLY FRIDAY AS STRONG UPPER TROUGH APPROACHES FROM THE
NORTHWEST...BUT THE THREAT OF SEVERE WEATHER APPEARS TO BE
DIMINISHING RATHER QUICKLY. OUT OF AN OVERABUNDANCE OF CAUTION PLAN
TO HANG ONTO THE BLUE BOX FOR OUR NW FEW COUNTIES FOR A BIT LONGER
BUT IF CURRENT WEAKENING TREND CONTINUES THEN WILL COORDINATE WITH
MKX AND SPC ON AN EARLY CANCELLATION OF THE WATCH BOX. EVENING
SOUNDINGS INDICATE THAT PWATS REMAIN OVER 150% OF AVERAGE...SO GIVEN
THE FAIRLY STRONG FORCING WITH THE APPROACHING UPPER TROUGH AND
MOIST ENVIRONMENT IT CERTAINLY SEEMS AS THOUGH THE PRIMARY THREAT
TONIGHT WILL BE HEAVY RAINFALL. THE DRY ANTECEDENT CONDITIONS OVER
MUCH OF THE CWA AND UNCERTAINTY REGARDING THE EXTENT OF
REDEVELOPMENT IN LIGHT OF THE CURRENT WEAKENING TRENDS PRECLUDE THE
NEED OF ANY FLOOD HEADLINES...BUT HEAVY RAIN THREAT WILL NEED TO BE
MONITORED TONIGHT.

IZZI

&&

.DISCUSSION...
327 PM CDT

MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND
THUNDERSTORMS THIS AFTERNOON/EVENING/OVERNIGHT/AND FRIDAY MORNING
ACROSS MUCH OF THE CWA.

IN THE WAKE OF A MID LEVEL WAVE/STRONG WAA WING AND ASSOCIATED
SHOWERS/THUNDERSTORMS...A MORE SUBSIDENT ENVIRONMENT CONTINUES TO
MOVE OVERHEAD. THIS HAS RESULTED IN A GOOD AMOUNT OF CLEARING
ACROSS MUCH OF NORTHERN ILLINOIS. ALTHOUGH THERE REMAINS SOME
ISOLATED DEVELOPMENT ACROSS EAST CENTRAL ILLINOIS AND PORTIONS OF
NORTHWEST INDIANA...THIS SHOULD REMAIN ISOLATED IN THIS LOCATION
OVER THE NEXT COUPLE OF HOURS BEFORE THIS THUNDERSTORM DEVELOPMENT
ALSO DIMINISHES...RIDING ALONG THE TAIL END OF THIS DEPARTING MID
LEVEL FEATURE. THEN...EXPECT MOST OF THE CWA TO REMAIN MOSTLY DRY
THROUGH THE 00-01Z TIME FRAME THIS EVENING...WITH BETTER LARGE
SCALE SUPPORT REMAINING WELL WEST OF THE CWA THROUGH THIS
AFTERNOON. LATEST OBSERVATIONS/RADAR IMAGERY DEPICTING LINGERING
BOUNDARY ACROSS NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THIS COULD SERVE AS A FOCUS FOR DEVELOPMENT...ONCE AGAIN LARGE
SCALE SUPPORT IS NOT THERE. WHAT THIS BOUNDARY IS DOING IS
CREATING DRASTIC DIFFERENCES IN TEMPERATURES ACROSS THE
AREA...WITH TEMPS HOVERING AROUND 90 DEGREES WEST OF THIS BOUNDARY
AND TEMPS STILL IN THE 70S EAST OF IT. CONTINUED PRESSURE FALLS
AND A TIGHTENING GRADIENT SHOULD HELP FOR A SYNOPTIC PUSH OF THIS
BOUNDARY TO THE NORTHEAST LATE THIS AFTERNOON. WITH THIS
OCCURRENCE...A VERY WARM AIRMASS WILL QUICKLY SPREAD EAST INTO
REMAINING AREAS IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
ALTHOUGH ITS GETTING LATE IN THE DAY...I STILL FEEL THAT THIS HAS
A CHANCE OF OCCURRING LATE THIS AFTERNOON/EARLY EVENING.

FOCUS THEN TURNS TOWARDS MORE WIDESPREAD THUNDERSTORM DEVELOPMENT
STILL EXPECTED AFTER THE 00Z TIME FRAME...AND PERSISTING THROUGH
THE OVERNIGHT HOURS AND EARLY FRIDAY MORNING. AS WEAK RIDGING IS
OCCURRING OVERHEAD...SOUTHWESTERLY FLOW ONGOING ACROSS MUCH OF THE
CENTRAL CONUS THIS AFTERNOON AS LARGE VORT MAX SLOWLY DIPS
EAST/SOUTHEAST ACROSS THE NORTHERN PLAINS. WITH PRESSURE FALLS
OCCURRING ACROSS MUCH OF THE REGION...A SURFACE TROUGH AND
ASSOCIATED COLD FRONT STRETCHES FROM MINNESOTA BACK SOUTHWEST
THROUGH IOWA AND INTO KANSAS. WITH THE CONTINUED SOUTHWARD
MOVEMENT OF THIS VORT MAX...FLOW WILL ENABLE SEVERAL WAVES MOVING
ACROSS THE CENTRAL AND SOUTHERN PLAINS TO LIFT NORTHEAST ACROSS
THE REGION...WITH THIS TROUGH/FRONT SHIFTING EAST TOWARDS THE CWA.
AS THIS OCCURS...EXPECT THUNDERSTORM DEVELOPMENT TO BE ON THE
INCREASE THIS EVENING. CURRENT OBSERVATIONS ARE INDICATING A
PREFRONTAL TROUGH OUT AHEAD OF THE MAIN FRONT...WITH LATEST RAP
ANALYSIS INDICATING MODERATE/STRONG SURFACE BASED INSTABILITY
ALONG IT. ALTHOUGH DEVELOPMENT SHOULD OCCUR ALONG THIS TROUGH OVER
THE NEXT SEVERAL HOURS...DONT ANTICIPATE MUCH IN TERMS LONGEVITY
OR STRENGTH OF ANY STORMS THAT DO DEVELOP ACROSS EASTERN
IOWA/WESTERN ILLINOIS IN THE NEAR TERM. FLOW ALOFT WILL CONTINUE
TO BE ORIENTED MORE SOUTH TO THE NORTH...WITH LARGE SCALE SUPPORT
STAYING JUST WEST OF THIS FEATURE. THEN BY THE 23Z TIME FRAME
EXPECT CURRENT THUNDERSTORM DEVELOPMENT OVER SOUTHWEST IOWA TO
QUICKLY SPREAD NORTHEAST INTO EASTERN IOWA AND WEST/NORTHWEST
ILLINOIS AS LARGE SCALE SUPPORT AND TROUGH/BOUNDARY SHIFT EAST.
WITH A VERY MOIST/UNSTABLE ATMOSPHERE IN PLACE AND HIGHER BULK
SHEAR VALUES SPREADING EAST...THUNDERSTORM DEVELOPMENT WILL HAVE
THE POTENTIAL TO BE STRONG/SEVERE WITH THE WESTERN HALF OF THE CWA
STILL HAVING THE BEST CHANCES TO OBSERVE THESE STRONGER STORMS.
BEST CHANCES TO OBSERVE STRONG/SEVERE STORMS WILL BE AREAS
WEST/NORTHWEST OF INTERSTATE 55. ALTHOUGH...AS WE ARE OBSERVING
CURRENTLY ACROSS IROQUOIS COUNTY...ANY STORM WILL HAVE THE
POTENTIAL TO BECOME STRONG TO SEVERE. ITS JUST THE MORE WIDESPREAD
DEVELOPMENT IS EXPECTED TO BE ACROSS THE WESTERN CWA. TIME
FRAME...AREAS ALONG AND WEST OF I-39 THRU 3Z...AREAS ALONG AND
WEST OF I-55 INTO 6Z...THEN SPREADING SOUTHEAST THROUGH THE
REMAINING CWA AFTER MIDNIGHT. THE EXTENT OF THE STRONGER STORMS
THROUGH THE OVERNIGHT HOURS IS LOW AT THIS TIME...BUT WITH AT
LEAST THE POSSIBILITY FOR ISOLATED STRONG TO SEVERE STORMS TO
REMAIN. HEAVY RAINFALL WILL BE AN ISSUE THIS EVENING AND OVERNIGHT
WITH LOCALIZED HEAVY DOWNPOURS AND EVEN LOCALIZED FLOODING A
POSSIBILITY...AS A VERY MOIST AIRMASS REMAINS OVERHEAD.

TROUGH/FRONT WILL CONTINUE TO SHIFT SOUTHEAST ALONG WITH PRECIP
SHIELD THROUGH FRIDAY...WITH LIKELY POPS STILL WARRANTED FOR MOST
AREAS DURING THE MORNING HOURS. THEN EXPECT DRYING TO OCCUR INTO
THE AFTERNOON AS MUCH COLDER AND DRIER AIR QUICKLY PUSHES
SOUTHEAST THROUGH THE CWA.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* REMNANT OUTFLOW BOUNDARY...POSSIBLY PRODUCING A BRIEF PERIOD OF
  GUSTY WEST WINDS AROUND 04 UTC.

* SHOWERS AND SOME THUNDERSTORMS OVERNIGHT...WITH SOME MODERATE
  RAIN POSSIBLE.


KJB

//DISCUSSION...UPDATED 00Z...

THE MAIN CONCERNS TONIGHT WILL BE TIMING OF CONVECTION AHEAD OF AN
APPROACHING COLD FRONT.

CURRENT REGIONAL RADAR IMAGERY INDICATES A CLUSTER OF STRONG TO
SEVERE STORMS MOVES EASTWARD ACROSS WISCONSIN. THIS ACTIVITY HAS
REMAINED NORTH OF THE STATE LINE. HOWEVER...AN OUTFLOW BOUNDARY IS
EVIDENT ALONG THE SOUTHWESTERN PERIPHERY OF THIS LINE OF CONVECTION.
THIS BOUNDARY COULD BE THE FOCUS OF SOME ISOLATED TO SCATTERED
THUNDERSTORMS EARLY THIS EVENING...PRIMARILY IN THE VICINITY OF
KRFD. OTHERWISE...IT APPEARS THE SECOND LINE OF STORMS ACROSS IOWA
WILL BE THE MAIN FOCUS FOR THE TERMINALS LATER THIS EVENING AND INTO
THE EARLY OVERNIGHT HOURS. CURRENT INDICATIONS ARE THAT THIS LINE OF
STORMS MAY APPROACH THE EASTERN TERMINALS IN THE 04 TO 06 UTC TIME
FRAME. WITH THIS LINE...THERE COULD BE A PERIOD OF VERY HEAVY
RAINFALL...AND POSSIBLY SOME WIND AS WELL. I CHOOSE TO ADD A TEMPO
GROUP NEAR THE EXPECTED ONSET OF THE CONVECTION TO SUGGEST THE
POTENTIAL FOR SOME VERY LOW VIS IN HEAVY TSRA. FOLLOWING THE LINE OF
MORE INTENSE CONVECTION...THERE COULD BE A FEW HOURS OF MODERATE
SHOWERS AND POSSIBLY SOME EMBEDDED THUNDER THROUGH AROUND 09 TO 10
UTC. FOLLOWING THE HEAVY RAINFALL...THERE COULD BE SOME LOWER CIGS
IN THE 1-2,000 FOOT RANGE INTO EARLY FRIDAY BEFORE CONDITIONS
IMPROVE BY MID MORNING WITH THE PASSAGE OF THE COLD FRONT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE IN SHOWER/THUNDERSTORM TIMING TONIGHT.

KJB

//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...

SATURDAY THROUGH WEDNESDAY...VFR. WX NIL.

KJB

&&

.MARINE...
239 PM CDT

LOW PRESSURE OVER FAR WESTERN ONTARIO WILL CONTINUE TO SLIDE EAST
TONIGHT TOWARDS JAMES BAY...WITH A TRAILING FRONTAL BOUNDARY
STRETCHING SOUTHWEST THROUGH THE WESTERN GREAT LAKES. THIS FRONTAL
BOUNDARY IS POISED TO PUSH EAST ACROSS LAKE MICHIGAN OVERNIGHT...AND
MAY LINGER ALONG THE FAR SOUTHERN PORTIONS OF LAKE MICHIGAN UNTIL
JUST AFTER DAYBREAK FRI. SOUTHERLY WINDS WILL CONTINUE TO SHIFT TO
THE SOUTHWEST THEN BEHIND THE FRONTAL BOUNDARY WINDS WILL TURN
NORTHWESTERLY TO NORTHERLY. AHEAD OF THE FRONTAL BOUNDARY OCCASIONAL
GUSTS TO 20-25KT MAY OCCUR ALONG THE SOUTHERN PORTION OF THE
LAKE...THEN THE GRADIENT BRIEFLY TIGHTENS WITH THE BOUNDARY AND
BEHIND THE FRONT. WINDS WILL THEN INCREASE TO 15 TO 25 KT FOR MUCH
OF THE LAKE OVER THE NEXT FEW DAYS AS THE GRADIENT WILL REMAIN
ELEVATED. IN ADDITION TO THE PROLONGED NORTHWEST FLOW AND INCREASED
GRADIENT...MUCH COOLER AIR WILL FLOW ACROSS THE WARMER LAKE SURFACE.
THIS WILL ALLOW WAVES TO EASILY BUILD AND REMAIN ELEVATED.

HIGH PRESSURE WILL FINALLY ARRIVE ACROSS THE WESTERN GREAT LAKES FOR
THE SECOND HALF OF THE UPCOMING WEEKEND AND ALLOW THE GRADIENT TO
DIMINISH...WITH WAVES SLOWLY SUBSIDING AS WELL. THEN ANOTHER UPPER
LEVEL RIDGE WILL APPROACH THE AREA FOR EARLY NEXT WEEK WITH WINDS
SLOWLY TURNING SOUTHERLY MON INTO TUE.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO NORTHERLY IS UNTIL 4 AM FRIDAY.

&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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  [top]

Area Forecast Discussion
National Weather Service Lincoln IL
857 PM CDT Thu Sep 19 2013

.DISCUSSION...
ISSUED 857 PM CDT Thu Sep 19 2013

Line of showers and thunderstorms moving into the area little
quicker than models seemed to indicate and what is in the grids.
So will be updating pops/wx in forecast for sooner onset of pcpn.
Skies will be cloudy overnight as well. Pcpn will linger overnight
across most of the area so may need to adjust pops/wx/qpf for
overnight as well. Remainder of forecast with temps and winds look
ok but may make minor tweaks in grids for remainder of the night.
Update will be coming out shortly.

Auten
&&

.AVIATION...
ISSUED 654 PM CDT Thu Sep 19 2013

All sites should be VFR through the period, except for maybe a
brief period of MVFR as a line of showers and storms move through
the area tonight. Models bring this line of showers and storms
into the area toward midnight, but current speed and radar trends
seem to show that the line will be coming in sooner. So have
changed start time of line of storms to sooner and added a tempo
group to all sites, though think line will diminish some as it
moves across the area this evening. 4km SPC-WRF and HRRR indicated
this, but both were also slower on bringing the line in, so think
pcpn maybe stronger as it moves into the area and then diminish
some as it moves toward DEC and CMI. Line is moving east, but
storms are moving northeast, so have tempo group for 3 hours and
then will keep light rain and VCTS for several hours after. Then
mid and high clouds should prevail once pcpn moves away from the
sites. Could be some lower clouds, but not confident enough to put
in TAFs at this time. Winds will be southwest and then become west
to northwest behind the line.

Auten
&&

.PREV DISCUSSION...
ISSUED 258 PM CDT Thu Sep 19 2013

Mid summer-like heat and humidity continue across central and
southeast Illinois in the southerly flow ahead of a cold front.
Scattered showers and thunderstorms are firing across the Midwest
in the uncapped and unstable airmass to the east of the front,
which currently extends from northwest Ontario into the southern
Plains. Main forecast concerns today revolve around precipitation
chances until the front clears the area on Friday. Otherwise, much
of the next several days should see quiet weather. It will be
cooler as well, albeit still above normal for late September.

12Z models in good agreement overall over the next several days.
However, there are some notable differences with respect to how
much rainfall is generated with the frontal passage, as well as
with some weak disturbances that pass near the area next week.
Considering the developing drought conditions and the way many
recent systems have behaved, have tended to lean toward the drier
solutions. At least in the very near term, this thinking is agreed
upon by many of the very short range/mesoscale models.

SHORT TERM...Tonight through Sunday: The cold front is progged to
enter the forecast area overnight, and exit the region to the east
Friday afternoon or early evening. The pre frontal airmass is
quite juicy, but the front will be moving through most of the area
at an unfavorable time of day instability wise (ie. late tonight
and Friday morning). The frontal timing should tend to limit storm
coverage and intensity, a fact agreed upon by many of the meso
models.

Much cooler temperatures will return to the area behind the front,
with readings near or below normal for the weekend. Canadian high
pressure and the associated dry airmass will keep conditions quiet
for the rest of the period post fropa.

LONG TERM...Monday through Thursday: Upper ridging will begin to
build across the area to start next week, and low level flow will
turn southerly as the surface high drifts off to the east. This
pattern shift will signal a return to above normal temperatures
for most of the week. Dry conditions should linger for the most
part as well. However, will need to keep an eye on a wave progged
to top the ridge around Tuesday. This system has the potential to
be a rain producer locally, although the best chances should stay
to our west and north.

Bak

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 821 PM CDT THU SEP 19 2013

.MESOSCALE DISCUSSION...
821 PM CDT

RADAR AND SATELLITE IMAGERY INDICATE THAT THE BOW ECHO OVER EASTERN
IOWA THAT HAD BEEN PLOWING EAST TOWARD THE CWA HAS BEGUN TO QUICKLY
SHRIVEL UP...MOST LIKELY DUE TO OUTRUNNING THE BETTER SHEAR AND
ENCOUNTERING INCREASING SURFACE BASE CONVECTIVE INHIBITION WITH
RATHER QUICK TEMP DROP OFF THAT OCCURRED AT SUNSET. SHOWERS AND
THUNDERSTORMS STILL EXPECTED TO MOVE ACROSS THE AREA OVERNIGHT INTO
EARLY FRIDAY AS STRONG UPPER TROUGH APPROACHES FROM THE
NORTHWEST...BUT THE THREAT OF SEVERE WEATHER APPEARS TO BE
DIMINISHING RATHER QUICKLY. OUT OF AN OVERABUNDANCE OF CAUTION PLAN
TO HANG ONTO THE BLUE BOX FOR OUR NW FEW COUNTIES FOR A BIT LONGER
BUT IF CURRENT WEAKENING TREND CONTINUES THEN WILL COORDINATE WITH
MKX AND SPC ON AN EARLY CANCELLATION OF THE WATCH BOX. EVENING
SOUNDINGS INDICATE THAT PWATS REMAIN OVER 150% OF AVERAGE...SO GIVEN
THE FAIRLY STRONG FORCING WITH THE APPROACHING UPPER TROUGH AND
MOIST ENVIRONMENT IT CERTAINLY SEEMS AS THOUGH THE PRIMARY THREAT
TONIGHT WILL BE HEAVY RAINFALL. THE DRY ANTECEDENT CONDITIONS OVER
MUCH OF THE CWA AND UNCERTAINTY REGARDING THE EXTENT OF
REDEVELOPMENT IN LIGHT OF THE CURRENT WEAKENING TRENDS PRECLUDE THE
NEED OF ANY FLOOD HEADLINES...BUT HEAVY RAIN THREAT WILL NEED TO BE
MONITORED TONIGHT.

IZZI

&&

.DISCUSSION...
327 PM CDT

MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND
THUNDERSTORMS THIS AFTERNOON/EVENING/OVERNIGHT/AND FRIDAY MORNING
ACROSS MUCH OF THE CWA.

IN THE WAKE OF A MID LEVEL WAVE/STRONG WAA WING AND ASSOCIATED
SHOWERS/THUNDERSTORMS...A MORE SUBSIDENT ENVIRONMENT CONTINUES TO
MOVE OVERHEAD. THIS HAS RESULTED IN A GOOD AMOUNT OF CLEARING
ACROSS MUCH OF NORTHERN ILLINOIS. ALTHOUGH THERE REMAINS SOME
ISOLATED DEVELOPMENT ACROSS EAST CENTRAL ILLINOIS AND PORTIONS OF
NORTHWEST INDIANA...THIS SHOULD REMAIN ISOLATED IN THIS LOCATION
OVER THE NEXT COUPLE OF HOURS BEFORE THIS THUNDERSTORM DEVELOPMENT
ALSO DIMINISHES...RIDING ALONG THE TAIL END OF THIS DEPARTING MID
LEVEL FEATURE. THEN...EXPECT MOST OF THE CWA TO REMAIN MOSTLY DRY
THROUGH THE 00-01Z TIME FRAME THIS EVENING...WITH BETTER LARGE
SCALE SUPPORT REMAINING WELL WEST OF THE CWA THROUGH THIS
AFTERNOON. LATEST OBSERVATIONS/RADAR IMAGERY DEPICTING LINGERING
BOUNDARY ACROSS NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH
THIS COULD SERVE AS A FOCUS FOR DEVELOPMENT...ONCE AGAIN LARGE
SCALE SUPPORT IS NOT THERE. WHAT THIS BOUNDARY IS DOING IS
CREATING DRASTIC DIFFERENCES IN TEMPERATURES ACROSS THE
AREA...WITH TEMPS HOVERING AROUND 90 DEGREES WEST OF THIS BOUNDARY
AND TEMPS STILL IN THE 70S EAST OF IT. CONTINUED PRESSURE FALLS
AND A TIGHTENING GRADIENT SHOULD HELP FOR A SYNOPTIC PUSH OF THIS
BOUNDARY TO THE NORTHEAST LATE THIS AFTERNOON. WITH THIS
OCCURRENCE...A VERY WARM AIRMASS WILL QUICKLY SPREAD EAST INTO
REMAINING AREAS IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
ALTHOUGH ITS GETTING LATE IN THE DAY...I STILL FEEL THAT THIS HAS
A CHANCE OF OCCURRING LATE THIS AFTERNOON/EARLY EVENING.

FOCUS THEN TURNS TOWARDS MORE WIDESPREAD THUNDERSTORM DEVELOPMENT
STILL EXPECTED AFTER THE 00Z TIME FRAME...AND PERSISTING THROUGH
THE OVERNIGHT HOURS AND EARLY FRIDAY MORNING. AS WEAK RIDGING IS
OCCURRING OVERHEAD...SOUTHWESTERLY FLOW ONGOING ACROSS MUCH OF THE
CENTRAL CONUS THIS AFTERNOON AS LARGE VORT MAX SLOWLY DIPS
EAST/SOUTHEAST ACROSS THE NORTHERN PLAINS. WITH PRESSURE FALLS
OCCURRING ACROSS MUCH OF THE REGION...A SURFACE TROUGH AND
ASSOCIATED COLD FRONT STRETCHES FROM MINNESOTA BACK SOUTHWEST
THROUGH IOWA AND INTO KANSAS. WITH THE CONTINUED SOUTHWARD
MOVEMENT OF THIS VORT MAX...FLOW WILL ENABLE SEVERAL WAVES MOVING
ACROSS THE CENTRAL AND SOUTHERN PLAINS TO LIFT NORTHEAST ACROSS
THE REGION...WITH THIS TROUGH/FRONT SHIFTING EAST TOWARDS THE CWA.
AS THIS OCCURS...EXPECT THUNDERSTORM DEVELOPMENT TO BE ON THE
INCREASE THIS EVENING. CURRENT OBSERVATIONS ARE INDICATING A
PREFRONTAL TROUGH OUT AHEAD OF THE MAIN FRONT...WITH LATEST RAP
ANALYSIS INDICATING MODERATE/STRONG SURFACE BASED INSTABILITY
ALONG IT. ALTHOUGH DEVELOPMENT SHOULD OCCUR ALONG THIS TROUGH OVER
THE NEXT SEVERAL HOURS...DONT ANTICIPATE MUCH IN TERMS LONGEVITY
OR STRENGTH OF ANY STORMS THAT DO DEVELOP ACROSS EASTERN
IOWA/WESTERN ILLINOIS IN THE NEAR TERM. FLOW ALOFT WILL CONTINUE
TO BE ORIENTED MORE SOUTH TO THE NORTH...WITH LARGE SCALE SUPPORT
STAYING JUST WEST OF THIS FEATURE. THEN BY THE 23Z TIME FRAME
EXPECT CURRENT THUNDERSTORM DEVELOPMENT OVER SOUTHWEST IOWA TO
QUICKLY SPREAD NORTHEAST INTO EASTERN IOWA AND WEST/NORTHWEST
ILLINOIS AS LARGE SCALE SUPPORT AND TROUGH/BOUNDARY SHIFT EAST.
WITH A VERY MOIST/UNSTABLE ATMOSPHERE IN PLACE AND HIGHER BULK
SHEAR VALUES SPREADING EAST...THUNDERSTORM DEVELOPMENT WILL HAVE
THE POTENTIAL TO BE STRONG/SEVERE WITH THE WESTERN HALF OF THE CWA
STILL HAVING THE BEST CHANCES TO OBSERVE THESE STRONGER STORMS.
BEST CHANCES TO OBSERVE STRONG/SEVERE STORMS WILL BE AREAS
WEST/NORTHWEST OF INTERSTATE 55. ALTHOUGH...AS WE ARE OBSERVING
CURRENTLY ACROSS IROQUOIS COUNTY...ANY STORM WILL HAVE THE
POTENTIAL TO BECOME STRONG TO SEVERE. ITS JUST THE MORE WIDESPREAD
DEVELOPMENT IS EXPECTED TO BE ACROSS THE WESTERN CWA. TIME
FRAME...AREAS ALONG AND WEST OF I-39 THRU 3Z...AREAS ALONG AND
WEST OF I-55 INTO 6Z...THEN SPREADING SOUTHEAST THROUGH THE
REMAINING CWA AFTER MIDNIGHT. THE EXTENT OF THE STRONGER STORMS
THROUGH THE OVERNIGHT HOURS IS LOW AT THIS TIME...BUT WITH AT
LEAST THE POSSIBILITY FOR ISOLATED STRONG TO SEVERE STORMS TO
REMAIN. HEAVY RAINFALL WILL BE AN ISSUE THIS EVENING AND OVERNIGHT
WITH LOCALIZED HEAVY DOWNPOURS AND EVEN LOCALIZED FLOODING A
POSSIBILITY...AS A VERY MOIST AIRMASS REMAINS OVERHEAD.

TROUGH/FRONT WILL CONTINUE TO SHIFT SOUTHEAST ALONG WITH PRECIP
SHIELD THROUGH FRIDAY...WITH LIKELY POPS STILL WARRANTED FOR MOST
AREAS DURING THE MORNING HOURS. THEN EXPECT DRYING TO OCCUR INTO
THE AFTERNOON AS MUCH COLDER AND DRIER AIR QUICKLY PUSHES
SOUTHEAST THROUGH THE CWA.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* CONVECTION FROM THE WEST MAKING IT WAY EASTWARD TOWARDS THE
  TERMINALS LATER THIS EVENING AFTER 03-04 UTC.

* PERIODS OF HEAVY RAINFALL FOR A PERIOD...LIKELY REDUCING THE VIS
  DOWN AROUND 1SM.

* POTENTIAL FOR SOME LOWER CIGS AND LINGERING SHRA EARLY FRIDAY
  MORNING...BEFORE CONDITIONS IMPROVE WITH THE COLD FRONTAL
  PASSAGE.

KJB

//DISCUSSION...UPDATED 00Z...

THE MAIN CONCERNS TONIGHT WILL BE TIMING OF CONVECTION AHEAD OF AN
APPROACHING COLD FRONT.

CURRENT REGIONAL RADAR IMAGERY INDICATES A CLUSTER OF STRONG TO
SEVERE STORMS MOVES EASTWARD ACROSS WISCONSIN. THIS ACTIVITY HAS
REMAINED NORTH OF THE STATE LINE. HOWEVER...AN OUTFLOW BOUNDARY IS
EVIDENT ALONG THE SOUTHWESTERN PERIPHERY OF THIS LINE OF CONVECTION.
THIS BOUNDARY COULD BE THE FOCUS OF SOME ISOLATED TO SCATTERED
THUNDERSTORMS EARLY THIS EVENING...PRIMARILY IN THE VICINITY OF
KRFD. OTHERWISE...IT APPEARS THE SECOND LINE OF STORMS ACROSS IOWA
WILL BE THE MAIN FOCUS FOR THE TERMINALS LATER THIS EVENING AND INTO
THE EARLY OVERNIGHT HOURS. CURRENT INDICATIONS ARE THAT THIS LINE OF
STORMS MAY APPROACH THE EASTERN TERMINALS IN THE 04 TO 06 UTC TIME
FRAME. WITH THIS LINE...THERE COULD BE A PERIOD OF VERY HEAVY
RAINFALL...AND POSSIBLY SOME WIND AS WELL. I CHOOSE TO ADD A TEMPO
GROUP NEAR THE EXPECTED ONSET OF THE CONVECTION TO SUGGEST THE
POTENTIAL FOR SOME VERY LOW VIS IN HEAVY TSRA. FOLLOWING THE LINE OF
MORE INTENSE CONVECTION...THERE COULD BE A FEW HOURS OF MODERATE
SHOWERS AND POSSIBLY SOME EMBEDDED THUNDER THROUGH AROUND 09 TO 10
UTC. FOLLOWING THE HEAVY RAINFALL...THERE COULD BE SOME LOWER CIGS
IN THE 1-2,000 FOOT RANGE INTO EARLY FRIDAY BEFORE CONDITIONS
IMPROVE BY MID MORNING WITH THE PASSAGE OF THE COLD FRONT.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE IN THUNDERSTORM TIMING TONIGHT.

KJB

//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...

SATURDAY THROUGH WEDNESDAY...VFR. WX NIL.

KJB

&&

.MARINE...
239 PM CDT

LOW PRESSURE OVER FAR WESTERN ONTARIO WILL CONTINUE TO SLIDE EAST
TONIGHT TOWARDS JAMES BAY...WITH A TRAILING FRONTAL BOUNDARY
STRETCHING SOUTHWEST THROUGH THE WESTERN GREAT LAKES. THIS FRONTAL
BOUNDARY IS POISED TO PUSH EAST ACROSS LAKE MICHIGAN OVERNIGHT...AND
MAY LINGER ALONG THE FAR SOUTHERN PORTIONS OF LAKE MICHIGAN UNTIL
JUST AFTER DAYBREAK FRI. SOUTHERLY WINDS WILL CONTINUE TO SHIFT TO
THE SOUTHWEST THEN BEHIND THE FRONTAL BOUNDARY WINDS WILL TURN
NORTHWESTERLY TO NORTHERLY. AHEAD OF THE FRONTAL BOUNDARY OCCASIONAL
GUSTS TO 20-25KT MAY OCCUR ALONG THE SOUTHERN PORTION OF THE
LAKE...THEN THE GRADIENT BRIEFLY TIGHTENS WITH THE BOUNDARY AND
BEHIND THE FRONT. WINDS WILL THEN INCREASE TO 15 TO 25 KT FOR MUCH
OF THE LAKE OVER THE NEXT FEW DAYS AS THE GRADIENT WILL REMAIN
ELEVATED. IN ADDITION TO THE PROLONGED NORTHWEST FLOW AND INCREASED
GRADIENT...MUCH COOLER AIR WILL FLOW ACROSS THE WARMER LAKE SURFACE.
THIS WILL ALLOW WAVES TO EASILY BUILD AND REMAIN ELEVATED.

HIGH PRESSURE WILL FINALLY ARRIVE ACROSS THE WESTERN GREAT LAKES FOR
THE SECOND HALF OF THE UPCOMING WEEKEND AND ALLOW THE GRADIENT TO
DIMINISH...WITH WAVES SLOWLY SUBSIDING AS WELL. THEN ANOTHER UPPER
LEVEL RIDGE WILL APPROACH THE AREA FOR EARLY NEXT WEEK WITH WINDS
SLOWLY TURNING SOUTHERLY MON INTO TUE.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







Area Forecast Discussion
National Weather Service Lincoln IL
654 PM CDT Thu Sep 19 2013

.DISCUSSION...
ISSUED 258 PM CDT Thu Sep 19 2013

Mid summer-like heat and humidity continue across central and
southeast Illinois in the southerly flow ahead of a cold front.
Scattered showers and thunderstorms are firing across the Midwest
in the uncapped and unstable airmass to the east of the front,
which currently extends from northwest Ontario into the southern
Plains. Main forecast concerns today revolve around precipitation
chances until the front clears the area on Friday. Otherwise, much
of the next several days should see quiet weather. It will be
cooler as well, albeit still above normal for late September.

12Z models in good agreement overall over the next several days.
However, there are some notable differences with respect to how
much rainfall is generated with the frontal passage, as well as
with some weak disturbances that pass near the area next week.
Considering the developing drought conditions and the way many
recent systems have behaved, have tended to lean toward the drier
solutions. At least in the very near term, this thinking is agreed
upon by many of the very short range/mesoscale models.

SHORT TERM...Tonight through Sunday: The cold front is progged to
enter the forecast area overnight, and exit the region to the east
Friday afternoon or early evening. The pre frontal airmass is
quite juicy, but the front will be moving through most of the area
at an unfavorable time of day instability wise (ie. late tonight
and Friday morning). The frontal timing should tend to limit storm
coverage and intensity, a fact agreed upon by many of the meso
models.

Much cooler temperatures will return to the area behind the front,
with readings near or below normal for the weekend. Canadian high
pressure and the associated dry airmass will keep conditions quiet
for the rest of the period post fropa.

LONG TERM...Monday through Thursday: Upper ridging will begin to
build across the area to start next week, and low level flow will
turn southerly as the surface high drifts off to the east. This
pattern shift will signal a return to above normal temperatures
for most of the week. Dry conditions should linger for the most
part as well. However, will need to keep an eye on a wave progged
to top the ridge around Tuesday. This system has the potential to
be a rain producer locally, although the best chances should stay
to our west and north.

Bak
&&

.AVIATION...
ISSUED 654 PM CDT Thu Sep 19 2013

All sites should be VFR through the period, except for maybe a
brief period of MVFR as a line of showers and storms move through
the area tonight. Models bring this line of showers and storms
into the area toward midnight, but current speed and radar trends
seem to show that the line will be coming in sooner. So have
changed start time of line of storms to sooner and added a tempo
group to all sites, though think line will diminish some as it
moves across the area this evening. 4km SPC-WRF and HRRR indicated
this, but both were also slower on bringing the line in, so think
pcpn maybe stronger as it moves into the area and then diminish
some as it moves toward DEC and CMI. Line is moving east, but
storms are moving northeast, so have tempo group for 3 hours and
then will keep light rain and VCTS for several hours after. Then
mid and high clouds should prevail once pcpn moves away from the
sites. Could be some lower clouds, but not confident enough to put
in TAFs at this time. Winds will be southwest and then become west
to northwest behind the line.

Auten
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 516 PM CDT WED SEP 18 2013

.DISCUSSION...
336 PM CDT

MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND
THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT
SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR
SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING.

CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH
CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY.
LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN
BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND
EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING.
MCV IS THE MAIN DRIVING FORCE FOR THESE
SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING
CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE
CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER
WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON
AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH
WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE
STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING
TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS
AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN
THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS
TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH
AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT.

WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD
OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES
WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH
LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS
AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS.
ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID
MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT
OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE
SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA
WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY
FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT
OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE.
ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE
AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS
PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE
LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR
MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD
COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL
BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90
DEGREES.

MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE
AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW
PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS
THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST
ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL
AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH
POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW
AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF
THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD
BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED
TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST
CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST
ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY
MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST
FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT
SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS
PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE
AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN
JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH
THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN
INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG
TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE
CWA.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* SCT SHRA AND A FEW ISOLATED TSRA EXPECTED THROUGH 23 TO 00 UTC
  THIS EVENING.

* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.

MDB/KB

//DISCUSSION...UPDATED 22Z...
A FEW ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED
ACROSS SOUTHERN MCHENRY AND FAR NORTHERN KANE COUNTIES OVER THE
PAST HOUR. THESE APPEAR TO BE ASSOCIATED WITH THE MAIN MID LEVEL
CIRCULATION MOVING ACROSS FAR NORTHERN ILLINOIS. CONFIDENCE ON IF
THESE STORMS WILL DIRECTLY MOVE ACROSS KORD IS LOW AT THIS
TIME...BUT IF THEY MAINTAIN THEMSELVES THEY COULD MOVE OVER KORD
SHORTLY AFTER 23 UTC. I WILL WATCH THESE CLOSELY TO SEE IF TSRA
NEEDS TO BE ADDED TO KORD FOR A SHORT PERIOD.

//DISCUSSION...UPDATED 20Z...

TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.

MDB

FROM 18Z...

BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH CONFIDENCE IN SHRA THROUGH 00 UTC.

* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
  MORNING IS LOW.

MDB/KB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
256 PM CDT

AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN
SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY
THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY.
AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE
MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF
THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE
HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES
FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER
THROUGH NORTH AND EAST TO SOUTHEAST.

TRS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 341 PM CDT WED SEP 18 2013

.DISCUSSION...
336 PM CDT

MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND
THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT
SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR
SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING.

CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH
CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY.
LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN
BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND
EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING.
MCV IS THE MAIN DRIVING FORCE FOR THESE
SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING
CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST
ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE
CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER
WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON
AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH
WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE
STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING
TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS
AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN
THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS
TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH
AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT.

WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD
OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES
WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH
LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS
AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS.
ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID
MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT
OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE
SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA
WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY
FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT
OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE.
ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE
AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS
PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE
LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR
MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD
COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL
BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90
DEGREES.

MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE
AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW
PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS
THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST
ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL
AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH
POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW
AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF
THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD
BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED
TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST
CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST
ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY
MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST
FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT
SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS
PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE
AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN
JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH
THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN
INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG
TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE
CWA.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* SHRA/TSRA EXPECTED IN THE AREA FROM 2030Z TIL 22 OR 23Z...MDW MAY
  SEE MOST DIRECT EFFECTS. BRIEF IFR VSBY POSSIBLE UNDER HEAVIEST
  CELLS.

* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 20Z...

TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.

MDB

FROM 18Z...

BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH CONFIDENCE IN TSRA OCCURRENCE AND TIMING.

* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
  MORNING IS LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
256 PM CDT

AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN
SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY
THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY.
AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE
MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF
THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE
HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES
FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER
THROUGH NORTH AND EAST TO SOUTHEAST.

TRS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 300 PM CDT WED SEP 18 2013

.DISCUSSION...
1057 AM CDT

MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.

TSRA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.

THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.

PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.

WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.

TRS

//PREV DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOBARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* SHRA/TSRA EXPECTED IN THE AREA FROM 2030Z TIL 22 OR 23Z...MDW MAY
  SEE MOST DIRECT EFFECTS. BRIEF IFR VSBY POSSIBLE UNDER HEAVIEST
  CELLS.

* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 20Z...

TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.

MDB

FROM 18Z...

BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH CONFIDENCE IN TSRA OCCURRENCE AND TIMING.

* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
  MORNING IS LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
256 PM CDT

AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN
SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY
THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY.
AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE
MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF
THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE
HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES
FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER
THROUGH NORTH AND EAST TO SOUTHEAST.

TRS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO









AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 245 PM CDT WED SEP 18 2013

.DISCUSSION...
1057 AM CDT

MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.

TSRA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.

THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.

PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.

WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.

TRS

//PREV DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* SHRA/TSRA EXPECTED IN THE AREA FROM 2030Z TIL 22 OR 23Z...MDW MAY
  SEE MOST DIRECT EFFECTS. BRIEF IFR VSBY POSSIBLE UNDER HEAVIEST
  CELLS.

* LOW CHANCE FOR ADDITIONAL SHRA/TSRA THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 20Z...

TSRA SITUATION HAS EVOLVED OVER THE LAST 2 HOURS. LOW LEVEL
CIRCULATION HAS CONTINUED TO DEVELOP AND HAS FOCUSED DEVELOPMENT
TO ITS SOUTHEAST LEADING TO HIGHER TSRA COVERAGE FROM DKB
SOUTHWESTWARD...WITH THE EARLIER AREA OF CONVECTION TO THE NORTH
SLOWLY FADING. BASED ON THESE TRENDS HAVE SPED UP TIMING OF TSRA
IN THE CHI AREA TAFS AND ADDED TSRA TO GYY. NEW ACTIVITY IS MOVING
A BIT MORE QUICKLY SO IT APPEARS THAT IT MAY BE CLEAR OF ORD/MDW
BY 22 OR 23Z AND GYY TOWARD 00Z OR A BIT AFTER.

MDB

FROM 18Z...

BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH CONFIDENCE IN TSRA OCCURRENCE AND TIMING.

* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
  MORNING IS LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 116 PM CDT WED SEP 18 2013

.DISCUSSION...
1057 AM CDT

MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.

TRSA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.

THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.

PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.

WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.

TRS

//PREV DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* POSSIBLE TSRA THIS AFTERNOON...ISOLATED CHANCE TOWARD 20Z WITH
  MORE ORGANIZED CHANCE 22 OR 23Z.

* LOW CHANCE FOR SHRA/TSRA THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 18Z...

BAND OF SHRA/TSRA CONTINUES TO MOVE EASTWARD INTO NORTH CENTRAL
ILLINOIS WITH SOME SPOTTY ACTIVITY NOW POPPING UP AHEAD OF IT.
WITH AN UPPER LEVEL WAVE LOOKING TO BE THE MAIN DRIVER OF THIS
PRECIP...POSSIBLY ALONG WITH A NEWLY DEVELOPED LOW LEVEL
CIRCULATION...A MORE EASTWARD TRACK LOOKS TO CONTINUE. THIS WILL
BRING THE ACTIVITY ACROSS RFD OVER THE NEXT FEW HOURS WITH THE CHI
METRO BEING AFFECTED MID/LATE AFTERNOON...WITH THE MOST ORGANIZED
COVERAGE EXPECTED 22/23Z OR SO. MOVEMENT HAS BEEN SLOW SO DURATION
IS A CONCERN BUT OVERALL COVERAGE HAS DECREASED. MAY NEED TO
UPDATE THE CHI AREA TAFS WITH A TEMPO GROUP. OTHERWISE THIS WILL
PASS BY EARLY EVENING LEAVING DRY CONDITIONS BUT A PUSH OF WARMER
AIR WILL ARRIVE LATER TONIGHT AND MAY KICK OFF SCATTERED SHRA/TSRA
DEVELOPMENT EARLY THURSDAY MORNING. CHANCE CONTINUES TO BE 20 TO
30 PERCENT SO OPTED TO KEEP VCSH AND PROB30 TS MENTION FOR NOW
WITH LOW CHANCES CONTINUING THROUGH THE REST OF THE DAY. SOUTH-
SOUTHWEST WINDS LOOK TO BECOME GUSTY BY LATE MORNING WITH GUSTS
AROUND 20 EXPECTED...THOUGH THERE IS SOME SUGGESTION OF 20-25 KT
GUSTS.

MDB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH CONFIDENCE THAT SHRA/TSRA WILL BE IN THE AREA
  MID/LATE AFTERNOON.

* MEDIUM-HIGH CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY
  MORNING IS LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 1116 AM CDT WED SEP 18 2013

.DISCUSSION...
1057 AM CDT

MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.

TRSA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.

THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.

PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.

WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.

TRS

//PREV DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* SSW WINDS WITH OCCASIONAL GUSTS NEAR 20 KT.

* SOME CHANCE FOR SHRA/TSRA TO BE NEARBY OR JUST NORTHWEST AFTER
  APPROX 21Z...BULK OF ACTIVITY EXPECTED TO REMAIN N OF TERMINALS.

* LOW CHANCE SHRA/TSRA EARLY THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 16Z...

STILL WATCHING CLUSTER OF SHRA/TSRA WORKING INTO FAR NW ILLINOIS
AT 16Z BUT TRENDS CONTINUE TO SHOW IT INCHING MORE TO THE NE.
EXPECT THIS NE TREND TO CONTINUE OVER THE NEXT FEW HOURS. RFD
LOOKS TO BE DIRECTLY AFFECTED AROUND 18Z...WITH THE ACTIVITY
PASSING NW OF ORD TOWARD OR AFTER 21Z IF THE SOUTHERN PORTION CAN
HOLD TOGETHER. SPOTTY ACTIVITY COULD OCCUR ACROSS THE CHICAGO AREA
AS THIS BAND PASSES TO THE NORTH BUT POTENTIAL IS TOO LOW TO
INCLUDE IN THE TAF. OTHERWISE WINDS HAVE COME AROUND TO S-SSW NOW
THAT SKIES HAVE SCATTERED TO SOME DEGREE AND SPORADIC GUSTS TO
NEAR 20 KT ARE EXPECTED.

MDB

FROM 12Z...

A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.

THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE IN SSW WINDS WITH OCCASIONAL GUSTS.

* MEDIUM CONFIDENCE THAT BULK OF TSRA TO THE WEST NOW WILL PASS NW
  OF THE TERMINALS...MEDIUM CONFIDENCE THAT SPOTTY ACTIVITY MAY
  OCCUR IN THE CHI AREA...AND MEDIUM-HIGH CONFIDENCE IN TIMING OF
  POTENTIAL.

* MEDIUM CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY MORNING IS
  LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 1059 AM CDT WED SEP 18 2013

.DISCUSSION...UPDATE FOR THIS AFTERNOON..
1057 AM CDT

MAIN SHORT TERM CONCERN IS POTENTIAL FOR EAST CENTRAL IA
THUNDERSTORMS REACHING THE WESTERN AND FAR NORTHER EASTERN
PORTIONS OF THE FORECAST AREA LATE THIS MORNING THROUGH THE FIRST
PART OF THE AFTERNOON. OTHER CONCERNS SKY COVER AND TEMPERATURE
TRENDS/MAX TEMPS.

TRSA THAT DEVELOPED OVER WESTERN IA LATE LAST NIGHT HAD BEEN
MOVING STEADILY NORTHEASTWARD DURING THE PREDAWN AND EARLY
MORNING HOURS BUT HAVE TAKEN ON A MORE EASTERLY DIRECTION OVER
THE LAST FEW HOURS AS THEY HAVE APPROACHED THE TOP OF A FLAT
UPPER RIDGE OVER THE LOCAL AREA IN THE WAKE OF THE COMPACT UPPER
LOW THAT HAD MOVED FROM OVER SOUTHERN LAKE MI TO WESTERN LAKE
ERIE SINCE LATE LAST NIGHT.

THIS CURRENT CONVECTION APPEARS TO BE WHERE LOWER AND MID LEVEL
WAA ARE MAXIMIZING ISENTROPIC ASCENT IN AN AREA OF STEEP MID
LEVEL LAPSE RATES. FORCING IN AN COINCIDING WITH AN AREA OF STEEP
MID LEVEL LAPSE RATES. LOWER AND MID LEVEL THETA-E ADVECTION
APPEARS TO BE ALSO HELPING IN THE TURN TO A MORE EASTERLY
MOVEMENT.

PURE EXTRAPOLATION OF THIS RECENT MOVEMENT WOULD LEAD ONE TO
BELIEVE THAT THE TSRA WOULD CONTINUE ACROSS NW TO N CENTRAL IL
AND NE IL DURING THE LATE MORNING THROUGH MID AFTERNOON.
HOWEVER...HIGHER RESOLUTION SHORT TERM MODEL OUTPUT INCLUDING
CONVECTIVE PRECIP...850-700 EQ POT TEMP ADV...K INDEX MID LEVEL
LAPSE RATES ARE SUGGESTING THAT THIS ACTIVITY WILL MAINTAIN AN
OVERALL ENE TO NE MOVEMENT PUTTING JUST N CENTRAL AND FAR NE IL
AT ANY SIGNIFICANT RISK OF SEEING THUNDERSTORMS.

WITH THE QUICK CLEARING FOLLOWING THE DEPARTURE OF THE UPPER LOW
EARLY THIS MORNING TEMPERATURES RESPONDED BY QUICKLY RISING INTO
THE LOWER AND MID 70S. WHILE SOME OF THE ANVIL FROM THE TS
CLUSTER IN FAR E CENTRAL IA IS EXPECTED TO MOVE THE NORTH PORTION
OF THE FA DURING THE AFTERNOON AND CUT INTO THE SURFACE
HEATING...FORECAST SOUNDINGS PREDICT HIGHS IN THE LOWER AND MID
80S... EXCEPT ALONG THE NORTH LAKE SHORE WHERE A LAKE BREEZE
EXPECTED TO MAKE LITTLE INLAND ADVANCEMENT KEEPS THIS AREA IN THE
MID 70S.

TRS

&&

.PREV DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* SPOTTY SHOWERS POSSIBLE THROUGH THE MORNING...ALSO WATCHING
  ACTIVITY ACROSS EASTERN IA WHICH LOOKS TO REMAIN NW OF THE
  TERMINALS EARLY AFTERNOON.

* SSE WINDS TURNING SSW...WITH GUSTS TO NEAR 20 KT POSSIBLE LATER
  THIS AFTERNOON.

* LOW CHANCE FOR SHRA/TSRA EARLY THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 14Z...

LOWEST VFR CIGS CONTINUE TO SCATTER ACROSS THE CHICAGO AREA BUT
SPOTTY SHOWERS CONTINUE TO DEVELOP AND WILL LIKELY CONTINUE TO DO
SO FOR A FEW HOURS. AM WATCHING CLUSTER OF SHRA/TSRA OVER EASTERN
IA WHICH HAS HAD SOME SCATTERED EXPANSION SOUTHWARD TOWARD KMUT
AND KFSW BUT AM EXPECTING THIS TO AIM MORE NORTHEASTWARD WITH TIME
IN CONJUNCTION WITH BETTER LOW/MID LEVEL ASCENT. WILL NEED TO
MONITOR BUT IT DOES APPEAR THAT THE SOUTHERN END OF THIS WILL PASS
NEAR OR OVER RFD BY MIDDAY WITH IT THEN PASSING NW OF THE CHI AREA
TERMINALS EARLY AFTERNOON. IF THERE IS ADDITIONAL SOUTHWARD
DEVELOPMENT THEN THE CHANCE OF ORD/DPA BEING AFFECTED WOULD
INCREASE. WINDS MAY TAKE A LITTLE LONGER TO TURN SSW THAN TAF
INDICATES.

MDB

FROM 12Z...

A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.

THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE THAT MORNING SHOWER ACTIVITY WILL REMAIN SPOTTY.
  MEDIUM CONFIDENCE THAT IA ACTIVITY WILL PASS TO THE NW...BUT
  WILL NEED TO KEEP AN EYE ON IT FOR EARLY AFTERNOON.

* MEDIUM-HIGH CONFIDENCE IN SSE WINDS TURNING SSW...LOW CONFIDENCE
  IN TIMING.

* MEDIUM CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY MORNING IS
  LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO

DISCLAIMER: NWS FACEBOOK...TWITTER AND YOUTUBE SITES ARE NOT
CONSIDERED OFFICIAL MEANS OF DISSEMINATING WEATHER INFORMATION
AND SHOULD NOT BE COUNTED ON AS SUCH.

OFFICIAL NWS.NOAA.GOV WEB SITES ARE MOST RELIABLE IN PROVIDING
TIMELY DELIVERY OF DATA AND PRODUCTS BUT EVEN THESE SOURCES
CANNOT BE GUARANTEED DUE TO THE NATURE OF THE INTERNET.






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 855 AM CDT WED SEP 18 2013

.DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* SPOTTY SHOWERS POSSIBLE THROUGH THE MORNING...ALSO WATCHING
  ACTIVITY ACROSS EASTERN IA WHICH LOOKS TO REMAIN NW OF THE
  TERMINALS EARLY AFTERNOON.

* SSE WINDS TURNING SSW...WITH GUSTS TO NEAR 20 KT POSSIBLE LATER
  THIS AFTERNOON.

* LOW CHANCE FOR SHRA/TSRA EARLY THURSDAY MORNING.

MDB

//DISCUSSION...UPDATED 14Z...

LOWEST VFR CIGS CONTINUE TO SCATTER ACROSS THE CHICAGO AREA BUT
SPOTTY SHOWERS CONTINUE TO DEVELOP AND WILL LIKELY CONTINUE TO DO
SO FOR A FEW HOURS. AM WATCHING CLUSTER OF SHRA/TSRA OVER EASTERN
IA WHICH HAS HAD SOME SCATTERED EXPANSION SOUTHWARD TOWARD KMUT
AND KFSW BUT AM EXPECTING THIS TO AIM MORE NORTHEASTWARD WITH TIME
IN CONJUNCTION WITH BETTER LOW/MID LEVEL ASCENT. WILL NEED TO
MONITOR BUT IT DOES APPEAR THAT THE SOUTHERN END OF THIS WILL PASS
NEAR OR OVER RFD BY MIDDAY WITH IT THEN PASSING NW OF THE CHI AREA
TERMINALS EARLY AFTERNOON. IF THERE IS ADDITIONAL SOUTHWARD
DEVELOPMENT THEN THE CHANCE OF ORD/DPA BEING AFFECTED WOULD
INCREASE. WINDS MAY TAKE A LITTLE LONGER TO TURN SSW THAN TAF
INDICATES.

MDB

FROM 12Z...

A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.

THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE THAT MORNING SHOWER ACTIVITY WILL REMAIN SPOTTY.
  MEDIUM CONFIDENCE THAT IA ACTIVITY WILL PASS TO THE NW...BUT
  WILL NEED TO KEEP AN EYE ON IT FOR EARLY AFTERNOON.

* MEDIUM-HIGH CONFIDENCE IN SSE WINDS TURNING SSW...LOW CONFIDENCE
  IN TIMING.

* MEDIUM CONFIDENCE THAT CHANCE FOR SHRA/TSRA THURSDAY MORNING IS
  LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 618 AM CDT WED SEP 18 2013

.DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* SLIGHT CHANCE FOR A FEW ISOLATED SHOWERS THROUGH LATE MORNING.

* ANOTHER SLIGHT CHANCE FOR SHOWERS OR THUNDERSTORMS EARLY
  TOMORROW MORNING.

* SOUTHERLY WINDS GUSTING TO ARND 20KT. STRONGEST GUSTS IN THE
  LATE AFTERNOON.

KREIN

//DISCUSSION...UPDATED 12Z...

A WEAK SHORTWAVE MOVING ACROSS THE AREA COMBINED WITH WARM
ADVECTION HAS GENERATED SOME ISOLATED SHOWERS ACROSS THE REGION.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...AND GENERALLY NORTH OF THE WISCONSIN BORDER.
HOWEVER...LATEST RADAR AND SATELLITE IMAGERY HAS INDICATED SOME
DEVELOPMENT OVER THE RFD AREA...SO...WILL KEEP SOME MENTION OF
PCPN IN THE FORECAST FOR THE RFD TERMINAL. OTHERWISE...EXPECT THE
REMAINDER OF THE TERMINALS TO REMAIN DRY TODAY. THERE WILL BE
ANOTHER CHANCE FOR SOME PCPN EARLY TOMORROW MORNING AS ANOTHER
SHORTWAVE CROSSES THE AREA...HOWEVER...THE GUIDANCE HAS NOT BEEN
VERY CONSISTENT IN THE THIS PCPN SIGNAL...SO CONFIDENCE IS LOW
THAT THE TERMINALS WILL BE DIRECTLY IMPACTED.

THE OTHER MAIN CONCERN FOR TODAY WILL BE WINDS. AS A LARGE AREA OF
HIGH PRESSURE SLIDES OFF THE MID ATLANTIC COAST...AND A SFC LOW
DEVELOPS OVER THE NRN PLAINS...A SOUTHERLY GRADIENT WILL STRENGTHEN
THROUGH THE DAY. WINDS WILL START OUT SELY THIS MORNING...BUT AS A
WEAK WARM FRONT LIFTS NWD...WINDS WILL VEER TO SLY AND STRENGTHEN
TO 10-12KT SUSTAINED. THROUGH THE MORNING...BREAKS IN THE
CLOUDINESS WILL ALLOW FOR SOME SUNSHINE AND INCREASED LOW LEVEL
MIXING AND STRONGER WINDS SHOULD BE ABLE TO MIX DOWN TO THE
SURFACE. LATEST SOUNDINGS SUGGEST THAT GUSTS SHOULD INCREASE FROM
LATE MORNING INTO THE AFTERNOON...WITH PEAK GUSTS TO ARND 20KT
THIS AFTERNOON.

KREIN


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* LOW CONFIDENCE IN SHRA DIRECTLY IMPACTING THE TERMINALS...AND
  MEDIUM CONFIDENCE THAT THE TERMINALS WILL REMAIN DRY.

* MEDIUM CONFIDENCE IN CIG TRENDS.

* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SLIGHT CHANCE OF TSRA LATE. OTRW...VFR.

FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY
LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY
IN THE AFTERNOON.

SATURDAY THROUGH TUESDAY...VFR. WX NIL.

KREIN

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 353 AM CDT WED SEP 18 2013

.DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SLIGHT CHANCE FOR A FEW ISOLATED SHOWERS THROUGH LATE MORNING.

* SOUTHERLY WINDS GUSTING TO ARND 20KT. STRONGEST GUSTS IN THE
  LATE AFTERNOON.

KREIN

//DISCUSSION...UPDATED 06Z...

A WEAK SHORTWAVE MOVING ACROSS THE AREA TONIGHT COMBINED WITH
WARM AIR ADVECTION HAS GENERATED SOME ISOLATED SHOWERS TO DEVELOP.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...SO THE GREATEST CHANCE FOR ANY SHRA TO IMPACT
ANY OF THE TERMINALS WILL BE AT RFD...THOUGH CANT RULE OUT A STRAY
SHOWER AS FAR EAST AS DPA. HOWEVER...IN GENERAL...CONFIDENCE IS
LOW THAT ANY PCPN WILL HAVE A SIGNIFICANT IMPACT ON ANY OF THE
TERMINALS. HAVE ADDED PROB30 GROUPS FOR NOW TO THE RFD/DPA TAFS.
THE MORE LIKELY SCENARIO WILL BE FOR LOWERING CLOUD BASES AS THE
WARM/MOIST ADVECTION SETS UP IN EARNEST OVER THE REGION...AND
BASED ON THE LATEST SATELLITE IMAGERY TRENDS AND MODEL RH
TIMESECTION FORECASTS...THERE IS A CHANCE THAT MVFR CIGS MAY SKIRT
THROUGH NCNTRL/NWRN IL...WITH RFD...AGAIN...THE MORE LIKELY
LOCATION TO SEE MVFR CIGS. EXPECT THAT THE TERMINALS TO THE EAST
WILL HAVE TOO MUCH DRIER AIR IN THE LOWEST LEVELS FOR BASES TO
LOWER TO MVFR.

AS A WEAK WARM FRONT LIFTS NORTH THROUGH NRN IL/IN DURG THE
MORNING HOURS...SELY WINDS WILL VEER SLY. THERE SHOULD BE ENOUGH
LOW LEVEL MIXING TO BRING SOME HIGHER GUSTS TO 15-18KT DOWN TO THE
SURFACE DURG THE LATE MORNING THROUGH EARLY EVENING.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* LOW CONFIDENCE IN SHRA DIRECTLY IMPACTING THE TERMINALS...AND
  MEDIUM CONFIDENCE THAT THE TERMINALS WILL REMAIN DRY.

* MEDIUM CONFIDENCE IN CIG TRENDS.

* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF TSRA IN THE AFTERNOON/EVENING. GUSTY
  SOUTHWEST WINDS.
* FRIDAY...SHRA/TSRA LIKELY. MVFR POSSIBLE. WIND SHIFT TO THE
  NORTHWEST IN THE AFTERNOON.
* SATURDAY THROUGH MONDAY...DRY/VFR. CMS

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 333 AM CDT WED SEP 18 2013

.DISCUSSION...
330 AM CDT

THE PRIMARY FORECAST CONCERNS ARE TEMPERATURES OVER THE NEXT
COUPLE DAYS AS READINGS REACH WELL ABOVE NORMAL VALUES....THEN
THUNDER CHANCES PRIMARILY THURSDAY NIGHT AND FRIDAY.

SYNOPSIS...A LONG WAVE TROUGH IS ADVANCING EAST OVER THE PACIFIC
NORTHWEST AND UPPER ROCKIES EARLY THIS MORNING...WITH A SOMEWHAT
FLATTENED UPPER RIDGE TRYING TO BUILD OVER THE EASTERN US. A
SERIES OF MID-LEVEL SHORT WAVES OWE TO THE FLATTENING OF THE RIDGE
AND ARE MOVING NORTHEAST OVER THE MIDWEST TO GREAT LAKES REGIONS
THIS MORNING. THESE IMPULSES AND BROAD WARM ADVECTION/WEAK
ISENTROPIC ASCENT ARE CAUSING SOME SHOWERS AND OCCASIONALLY A
LIGHTNING STRIKE OR TWO NEAR THE VORT CENTERS /NONE OF WHICH HAVE
OR LOOK TO CROSS OVER OUR CWA/. SOUTHEAST SURFACE WINDS WILL
CONTINUE TO VEER TO MORE SOUTHERLY BY THIS AFTERNOON AS A SURFACE
WARM FRONT BASICALLY EVOLVES NORTHEAST OVER THE AREA. THE WARM
SECTOR WILL PREVAIL TONIGHT THROUGH THURSDAY NIGHT BEFORE THE
AFOREMENTIONED TROUGH PROGRESSES A COLD FRONT INTO THE REGION.
THIS LOOKS TO MOVE THROUGH THE CWA FRIDAY WITH MAINLY SEASONAL
TEMPERATURES AND QUIET CONDITIONS AFTER THANKS TO PACIFIC/MODIFIED
CANADIAN HIGH PRESSURE.

TODAY...OVER THE PAST 12 HOURS THE SHOWER ACTIVITY ON THIS LEADING
PUSH OF WARM AIR ADVECTION HAS BEEN FAIRLY MEAGER IN THE
AREA...WITH GREATEST REGIONAL CONCENTRATION NEAR VORT MAX CENTERS.
VAD PROFILERS INDICATE AROUND 30 KT OF SSW LOW-LEVEL JET AROUND 2KFT
OVER THE AREA WITH SUBTLE ISENTROPIC OMEGA ABOVE THIS ON RAP AND
NAM FIELDS. WATER VAPOR REALLY DOES NOT INDICATE ANY FOCUSED VORT
MOVING OVER OUR AREA THIS MORNING SO HAVE JUST KEPT MAINLY
ISOLATED SHOWERS MENTION...WITH MORE SCATTERED WORDING IN THE
NORTH WHERE ALSO INCLUDE THE SMALL CHANCE OF THUNDER.

SATELLITE AND DIAGNOSTIC SOUNDINGS POINT TOWARD MULTIPLE CLOUD
LAYERS AT PRESENT BUT NONE THAT ARE OVERLY THICK WITH SOME HOLES
ACROSS MO/IA/WESTERN IL. WITH LOW-LEVEL SW FLOW HANGING IN THERE
THROUGH THE DAY...FORESEE THE BACK EDGE OF THE CLOUDS ADVANCING
NORTHEAST INTO AND POSSIBLY EVEN THROUGH MUCH OF THE CWA DURING
THE LATE MORNING TO MID AFTERNOON. HIGH RES MODEL RH AND COLUMN
CONDENSATE FIELDS REFLECT A SCATTERING/CLEARING TREND INTO THIS
AFTERNOON. CONFIDENCE IS CERTAINLY HIGHEST IN THE SOUTHERN AND
WESTERN CWA AND THERE IS WHERE MAINTAIN THE HIGHEST TEMPS...OR
THOSE SUPPORTED BY MIXING AND LOCAL CLIMO /LOW TO MID 80S/. THE
CHICAGO AREA SHOULD BE ONE OF THE LAST TO CLEAR BUT STILL SHOULD
BE IN ENOUGH TIME TO APPROACH 80. THE SYNOPTIC WIND DOES FAVOR A
SLIGHT LAKE PUSH THIS AFTERNOON...SO MID 70S OR SO SHOULD PREVAIL
DOWNTOWN.

TONIGHT AND THURSDAY...THROUGHOUT THIS PERIOD THERE REMAINS LITTLE
IN THE WAY OF FOCUS AND WHAT SEEMINGLY IS FAR TOO WIDESPREAD OF
QPF FROM MOST 18.00 GUIDANCE. THE FOCUS OF THE LOW-LEVEL JET NOSE
AND WARM AIR ADVECTION LOOKS TO BE WELL NORTH OF THE REGION.
SUBTLE SHORT WAVE ENERGY IS HINTED AT...ESPECIALLY BY THE
GFS...BUT IT SEEMS TOO FAR NORTH WITH SHORT WAVE MOVING OVER OK
THIS MORNING AND BRINGS THAT ACROSS THE CWA. HAVE KEPT MAINLY A
SLIGHT CHC FOR STORMS ACROSS THE REGION...BUT ALL IN ALL NOT REAL
EXCITED TONIGHT OR DURING THE DAYTIME THU. QUITE A MILD LATTER
SEPT NIGHT IS IN STORE WITH MID 60S TO EVEN LOWER 70S IN PARTS OF
CHICAGO. CONFIDENCE ON THE BALMY TEMPS THU CONTINUES TO INCH
UPWARD. WHILE SOME CLOUDS ARE POSSIBLE OVERNIGHT AND THU MORNING
WITH THE INCREASING PWAT/MOISTURE TRANSPORT AIR...AT THIS TIME IT
WOULD NOT SEEM TO BE MUCH OF A HINDRANCE ON WARMING. LOCAL
CLIMATOLOGY BASED OFF OF SREF FORECAST 850MB TEMPS AROUND 20C AND
925MB TEMPS OF 25C WOULD SUPPORT AROUND 90. BEST PERFORMING
GUIDANCE BLENDS ON SOME OF OUR WARM DAYS IN THE PAST MONTH WERE
BLENDED INTO THE GOING FORECAST AND INCHED UP A BIT FROM
THERE...ESPECIALLY SOUTH OF I-80 WHERE CONFIDENCE IS HIGHEST.
HIGHS LOOK TO BE AT OR WITHIN 5F OF RECORDS IN MANY AREAS.

THURSDAY NIGHT AND FRIDAY...THIS REMAINS THE PERIOD OF GREATEST
FORCING DUE TO FRONTAL CONVERGENCE...HIGH MOISTURE...AND LARGER
SCALE LIFT. THE TREND THE PAST 24 HOURS CONTINUES TO BE A SLIGHT
SLOW DOWN OF THE FRONT. THIS AGAIN MAKES SENSE GIVEN THE SURFACE
LOW AND ISALLOABARIC/ADVECTION COUPLET MOVING NORTHEASTWARD INTO
WESTERN ONTARIO AND THE FRONT STRETCHING OUT SOMEWHAT. INITIATION
OF MOST WIDESPREAD SHOWERS AND STORMS ON THU LATE AFTERNOON AND
EVE LOOKS TO BE OVER IA INTO SOUTHWEST WI/SOUTHEAST MN WHICH IS
THE FOCUS OF THE SPC DAY 2 SLIGHT RISK. LIMITED DYNAMICS AND SHEAR
ARE INITIALLY IN PLACE OVER THE CWA DURING THU EVE...WHICH IS THE
TIME OF GREATEST INSTABILITY...SO THAT DISJOINT LOOKS TO PREVENT A
SEVERE RISK GREATER THAN ISOLATED...AT LEAST AT THIS TIME. THE
BEST COVERAGE OF PRECIP LOOKS TO BE OVERNIGHT AND THEN WORKING
EASTWARD FRI. TOUGH TO SAY IF THERE WILL BE A REDEVELOPMENT OF
CONVECTION ALONG THE FRONT OR IF SHOWERS AND STORMS FROM THU NIGHT
JUST CONTINUE ON EASTWARD AS IS. OVERALL THE COVERAGE CONTINUES
TO LOOK HIGH ENOUGH TO WARRANT LIKELY POPS AND WILL PROBABLY SEE
THE INCLUSION OF CATEGORICAL AT SOME POINT FOR AT LEAST THE
WESTERN FORECAST AREA. PWATS NEARING THE 99TH PERCENTILE FOR SEPT
AND HIGH MOISTURE TRANSPORT/REPLENISHMENT FORECAST THU NIGHT WOULD
LEAD TO EFFICIENT RAIN MAKERS IN SOME OF THE CONVECTION. SO
CONTINUE TO GO HIGHER WITH QPF THAN A GUIDANCE BLEND...WITH SOME
AREAS OF THE WESTERN CWA SEEING OVER AN INCH CERTAINLY PLAUSIBLE.

THIS WEEKEND AND BEYOND...GIVEN THE FORECAST WEATHER PATTERN
LITTLE CHANGE WAS NEEDED TO A SMART GUIDANCE BLEND WITH GOING
FORECAST. NORTHWEST FLOW ON SATURDAY WILL USHER IN COOLER AIR AND
THEN SORT OF A BACKDOOR TURN TO NNE WINDS SAT NIGHT SHOULD INCH
HIGHS DOWN IN LAKE ADJACENT COUNTIES FOR SUNDAY. A GENERALLY DRY
PATTERN LOOKS TO BE THE RULE THIS WEEKEND INTO MUCH OF THE FIRST
HALF OF NEXT WEEK.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SLIGHT CHANCE FOR A FEW ISOLATED SHOWERS THROUGH LATE MORNING.

* GUSTY SOUTHERLY WINDS TO ARND 15-18KT.

KREIN

//DISCUSSION...UPDATED 06Z...

A WEAK SHORTWAVE MOVING ACROSS THE AREA TONIGHT COMBINED WITH
WARM AIR ADVECTION HAS GENERATED SOME ISOLATED SHOWERS TO DEVELOP.
HOWEVER...THE STRONGEST FOCUS WILL ALIGN FROM NERN IOWA INTO
CENTRAL WISCONSIN...SO THE GREATEST CHANCE FOR ANY SHRA TO IMPACT
ANY OF THE TERMINALS WILL BE AT RFD...THOUGH CANT RULE OUT A STRAY
SHOWER AS FAR EAST AS DPA. HOWEVER...IN GENERAL...CONFIDENCE IS
LOW THAT ANY PCPN WILL HAVE A SIGNIFICANT IMPACT ON ANY OF THE
TERMINALS. HAVE ADDED PROB30 GROUPS FOR NOW TO THE RFD/DPA TAFS.
THE MORE LIKELY SCENARIO WILL BE FOR LOWERING CLOUD BASES AS THE
WARM/MOIST ADVECTION SETS UP IN EARNEST OVER THE REGION...AND
BASED ON THE LATEST SATELLITE IMAGERY TRENDS AND MODEL RH
TIMESECTION FORECASTS...THERE IS A CHANCE THAT MVFR CIGS MAY SKIRT
THROUGH NCNTRL/NWRN IL...WITH RFD...AGAIN...THE MORE LIKELY
LOCATION TO SEE MVFR CIGS. EXPECT THAT THE TERMINALS TO THE EAST
WILL HAVE TOO MUCH DRIER AIR IN THE LOWEST LEVELS FOR BASES TO
LOWER TO MVFR.

AS A WEAK WARM FRONT LIFTS NORTH THROUGH NRN IL/IN DURG THE
MORNING HOURS...SELY WINDS WILL VEER SLY. THERE SHOULD BE ENOUGH
LOW LEVEL MIXING TO BRING SOME HIGHER GUSTS TO 15-18KT DOWN TO THE
SURFACE DURG THE LATE MORNING THROUGH EARLY EVENING.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* LOW CONFIDENCE IN SHRA DIRECTLY IMPACTING THE TERMINALS...AND
  MEDIUM CONFIDENCE THAT THE TERMINALS WILL REMAIN DRY.

* MEDIUM CONFIDENCE IN CIG TRENDS.

* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS.

KREIN

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

* THURSDAY...CHANCE OF TSRA IN THE AFTERNOON/EVENING. GUSTY
  SOUTHWEST WINDS.
* FRIDAY...SHRA/TSRA LIKELY. MVFR POSSIBLE. WIND SHIFT TO THE
  NORTHWEST IN THE AFTERNOON.
* SATURDAY THROUGH MONDAY...DRY/VFR. CMS

&&

.MARINE...
255 AM CDT

A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER UPSTATE NEW YORK
WILL WEAKEN AS IT SLIDES SOUTHEAST OFF THE ATLANTIC COAST TODAY.
MEANWHILE...LOW PRESSURE OVER THE DAKOTAS WILL MOVE NORTHEAST TO
WESTERN ONTARIO BY THURSDAY. ON THURSDAY NIGHT AND FRIDAY...A COLD
FRONT TRAILING FROM THIS LOW WILL SWEEP ACROSS LAKE MICHIGAN
THURSDAY NIGHT AND FRIDAY...SHARPLY VEERING WINDS FROM SOUTHERLY
TO NORTHWESTERLY. THE LOW WILL THEN DEEPENS FARTHER AS IT MOVES
OVER SOUTHERN HUDSON BAY FRIDAY NIGHT. THE LOW WILL WEAKEN AS IT
CONTINUES NORTHEAST ACROSS NORTHERN QUEBEC ON SATURDAY. HIGH
PRESSURE IS EXPECTED TO SPREAD SOUTHEAST FROM CENTRAL CANADA TO
THE GREAT LAKES SATURDAY.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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AREA FORECAST DISCUSSION

NWS NORTHERN INDIANA

 913 PM EDT THU SEP 19 2013

.SYNOPSIS...
ISSUED AT 819 PM EDT THU SEP 19 2013

A WARM FRONTAL BOUNDARY MOVING THROUGH THE AREA TONIGHT COMBINED
WITH ADDITIONAL WEAK UPPER LEVEL DISTURBANCES WILL RESULT IN A
CONTINUED CHANCE OF THUNDERSTORMS THROUGH EARLY FRIDAY
MORNING...PARTICULARLY ACROSS NORTHWEST AND NORTH CENTRAL INDIANA
ALONG WITH SOUTHERN LOWER MICHIGAN. A STRONG UPPER LEVEL SYSTEM
WILL APPROACH THE GREAT LAKES REGION FRIDAY ALLOWING A COLD FRONT
TO MOVE INTO THE AREA. THIS WILL RESULT IN A LIKELIHOOD OF SHOWERS
AND THUNDERSTORMS FRIDAY AND FRIDAY NIGHT. DRY CONDITIONS WILL
RETURN FOR SATURDAY...WITH MUCH COOLER CONDITIONS BEHIND THE COLD
FRONT.

&&

.UPDATE...
ISSUED AT 819 PM EDT THU SEP 19 2013

EARLIER SCATTERED THUNDERSTORMS WHICH DEVELOPED IN VICINITY OF
SURFACE TROUGH/WARM FRONT FEATURE HAVE DIMINISHED OVER PAST FEW
HOURS AS LOW LEVEL CIN HAS INCREASED. RUC 00Z ANALYSIS STILL
DEPICTS AXIS OF 2000-2500 J/KG OF 100 HPA MLCAPES FROM EXTREME
WEST CENTRAL INDIANA INTO NORTHEAST ILLINOIS ALONG BROAD LOW LEVEL
CONFLUENCE ZONE. MORE ORGANIZED CONVECTIVE ACTIVITY REMAINS ACROSS
THE MID MS RIVER VALLEY AND APPROACHING THE WESTERN GREAT LAKES
WITH SEVERAL OUTFLOWS ASSOCIATED WITH THIS ACTIVITY. HAVE
MAINTAINED TREND OF INCREASING POPS TO MID TO HIGH CHANCE AGAIN
OVERNIGHT ACROSS THE NORTHWEST AS SMALLER SCALE PERTURBATIONS KICK
OUT OF CENTRAL CONUS TROUGH...WITH RESIDUAL OUTFLOW BOUNDARIES
PERHAPS PROVIDING SOME FOCUS. ONLY CHANGE TO PREVIOUS FORECAST WAS
TO MAKE SMALL ADJUSTMENTS IN LOWERING EVENING POPS FOLLOWING
OBSERVATIONAL TRENDS AND DECAY OF LATE AFTERNOON CONVECTION.

&&

.SHORT TERM...(LATE THIS AFTERNOON THROUGH FRIDAY)
ISSUED AT 347 PM EDT THU SEP 19 2013

MAIN FOCUS FOR THE REMAINDER OF THE AFTERNOON WILL BE ON BATCH OF
RAIN/THUNDER THAT WILL CONTINUE TO SINK SOUTHEAST THROUGH THE IWX
CWA. THIS ACTIVITY IS TIED TO A WEAK MCV NOW INTO WESTERN
MICHIGAN...WHICH HAS HELPED ENHANCE DEEP MOIST CONVERGENCE ALONG A
SFC WARM FRONT THAT HAS MIXED INTO OUR FAR SOUTHWESTERN CWA AS OF
19Z. THERE IS SOME CONCERN FOR AN ISOLATED STRONG/SEVERE CELL
ALONG THIS SFC FRONT SOUTH OF HWY 30 AND WEST OF HWY 15 IN INDIANA
GIVEN MORE PRONOUNCED LOW LEVEL CONVERGENCE AND MODERATE MLCAPE
VALUES HERE. MARGINAL DEEP LAYERED FLOW/SHEAR WILL KEEP THIS AN
ISOLATED WIND/HAIL THREAT. SMALL MBE VECTORS/TRAINING WITH PWAT
VALUES NEAR 1.80 INCHES MAY SUPPORT SOME ADDITIONAL LOCALIZED
FLOODING/HEAVY RAIN ACROSS MAINLY OUR INDIANA ZONES INTO THE LATE
AFTERNOON.

MCS SHOULD SETTLE SOUTH AND EAST OF THE LOCAL AREA THIS EVENING INTO
THE OVERNIGHT...LEAVING A WEAK LOW LEVEL BOUNDARY DRAPED OVER THE
AREA IN ITS WAKE. CHANCES FOR ISOLATED TO SCATTERED CONVECTION INVOF
THIS BOUNDARY APPEAR RATHER LOW THIS EVENING BUT INCREASE A BIT
LATER TONIGHT AS A SMALLER SCALE LEAD SHORTWAVE EJECTS OUT OF THE
CENTRAL HIGH PLAINS AND PROPAGATES INTO THE MISSOURI VALLEY AND
WESTERN GREAT LAKES. AFTERNOON WATER VAPOR ALSO SHOWS TROPICAL
MOISTURE FROM HURRICANE MANUAL BEING PICKED UP INTO THE SOUTHERN
PLAINS IN ADVANCE OF THIS FEATURE AND UPPER TROUGH. THIS SECONDARY
SHOT OF MOISTURE ADVECTION AND NARROW RIBBON OF CYCLONIC VORTICITY
MAY BE ENOUGH TO GENERATE ADDITIONAL SCATTERED CONVECTION BY
LATER TONIGHT...BEST CHANCES ACROSS NORTHWEST INDIANA AND SW LOWER
MICHIGAN.

AN UPPER LEVEL TROUGH ACROSS THE CANADIAN PRAIRIES AND NORTHERN HIGH
PLAINS WILL AMPLIFY EAST INTO THE UPPER MIDWEST AND MID MS VALLEY BY
TOMORROW. DEEPENING SFC REFLECTION IN AREA OF STRONGER CYCLONIC
VORTICITY ADVECTION DOWNSTREAM OF TROUGH AXIS WILL TRACK
NORTHEAST THROUGH THE NORTHERN GREAT LAKES AND ONTARIO. THIS WILL
FORCE A TRAILING COLD FRONT INTO OUR NORTHWESTERN ZONES FRIDAY
MORNING AND CENTRAL/EASTERN ZONES BY FRIDAY AFTERNOON. CHANCES FOR
SHOWERS/STORMS STILL LOOKING GOOD INVOF THE FRONT GIVEN 60-80
METER 500 MB HEIGHT FALLS OVER DEEP PRE-FRONTAL MOISTURE PLUME
(PWATS AT LEAST 1.75 INCHES AND 1000-850 MB MIXING RATIOS NEAR 14
G/KG). THERE COULD BE A LULL IN COVERAGE/INTENSITY OF SHOWERS IN
THE MORNING BEHIND THE AFOREMENTIONED LEAD WAVE...BUT EXPECT THIS
TO FILL BACK IN WITH SOME HEATING AS DEEPER TROPOSPHERIC ASCENT
PIVOTS IN. LOCALIZED HEAVY RAIN WILL CONTINUE TO BE A
CONCERN...ESPECIALLY IN AREAS THAT HAVE ALREADY SEEN HEAVY RAIN
TODAY. SPC HAS AREAS ALONG/EAST OF A KOKOMO-WARSAW-COLDWATER LINE
HIGHLIGHTED IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW AFTERNOON.
STRONG FRONTAL SCALE FORCING COMBINED WITH THE POTENTIAL FOR WEAK
TO MODERATE BOUNDARY LAYER DESTABILIZATION MAY SUPPORT SOME
OVERACHIEVING UPDRAFTS...ALTHOUGH STRONGER FLOW/SHEAR NEEDED FOR
UPDRAFT/DOWNDRAFT SEPARATION AND ORGANIZATION WILL LIKELY LAG JUST
BEHIND THE FRONT. THUS...EXPECT LINGERING CLOUD COVER AND MARGINAL
SHEAR TO LIMIT THIS TO AN ISOLATED WIND/HAIL THREAT AT BEST.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 345 PM EDT THU SEP 19 2013

STRONG UPR LEVEL TROF OVER THE NRN PLAINS THIS AFTN WILL MOVE INTO
THE GRTLKS FRI NGT WHILE ACCOMPANYING CDFNT OUT AHEAD OF THE UPPER
FEATURE MOVES TO THE EAST OF THE CWA OVERNIGHT. MODELS IN GOOD
AGREEMENT THAT SHOWERS/TSTMS WILL BE ONGOING NEAR THE FRONT FRI EVE
SO BUMPED UP POPS IN THE EAST TO CATEGORICAL FOR THAT TIMEFRAME.
NAM/SREF A LITTLE QUICKER TO MOVE FRONT EAST OF THE CWA OVERNIGHT.
PREFER SLOWER GFS/ECMWF WHICH HAVE HAD BETTER RECENT RUN-RUN
CONTINUITY IN THIS REGARD... THUS MAINTAINED DIMINISHING RAIN
CHANCES OVERNIGHT WITH A SMALL CHC INTO EARLY SAT MORNING FAR EAST.
GFS/ECMWF SUGGESTING SOME POST-FRONTAL/LAKE ENHANCED SHOWERS PSBL
NWRN PORTION OF THE CWA SATURDAY AS UPR TROF SWINGS EAST THROUGH
LOWER MICHIGAN AND DELTA T`S INCREASE TO NEAR 13C. PREFER DRY
NAM/SREF SOLUTION IN OUR AREA AS AIRMASS IS FCST BY ALL MODELS TO BE
FAIRLY DRY... ESPECIALLY ALOFT... AND SUBSIDENCE INVERSION LEVEL
ONLY AROUND 5KFT. SFC HIGH FOLLOWING THE FRONT IS EXPECTED TO MOVE
ESE ACROSS THE UPR GRTLKS OVER THE REMAINDER OF THE WEEKEND
PROVIDING COOL/DRY WX. MODELS HAVE TRENDED A LITTLE MORE AMPLIFIED
WITH THE UPR FLOW AND ASSOCIATED LOW LEVEL CAA THIS WEEKEND... THUS
MADE MINOR DOWNWARD ADJUSTMENTS TO TEMPS WITH HIGHS FCST IN THE
L-M60S AND LOWS IN THE L-M40S.

UPR LEVEL RIDGE EXPECTED TO BUILD INTO THE GRTLKS REGION BY MONDAY
AND PERSIST THROUGH THURSDAY AS A SERIES OF SHRTWVS DIG SEWD FROM
THE NE PACIFIC INTO THE WRN U.S.. THIS SHOULD RESULT IN DRY WX
ACROSS OUR CWA THROUGH THIS PERIOD WITH TEMPS WARMING TO ABOVE
NORMAL READINGS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 819 PM EDT THU SEP 19 2013

CONVECTION ACROSS NORTHWEST INDIANA HAS DIMINISHED OVER PAST FEW
HOURS. SMALLER SCALE DISTURBANCES EMANATING FROM MORE SIGNIFICANT
UPPER TROUGH ACROSS THE CENTRAL UNITED STATES WILL DAMPEN THE
UPPER RIDGE IN PLACE ACROSS THE WESTERN GREAT LAKES. WITH SFC
TROUGH/WARM FRONTAL FEATURE IN THE VICINITY AND POSSIBLE
INTERACTION FROM UPSTREAM OUTFLOW BOUNDARIES...SOME CONVECTIVE
REDEVELOPMENT IS POSSIBLE OVERNIGHT PARTICUARLY ACROSS
NORTHWEST/NORTH CENTRAL INDIANA. WITH CONFIDENCE SOMEWHAT LOW
OVERNIGHT...HAVE MAINTAINED JUST VCTS MENTION AT KSBN. HAVE ALSO
MADE NO CHANGE TO TREND TO MVFR CONDS OVERNIGHT WITH ABUNDANT LOW
LEVEL MOISTURE AND WARM FRONTAL BOUNDARY IN VICINITY. UPSTREAM
CONVECTION ACROSS MID MS RIVER VALLEY SHOULD OVERSPREAD THE AREA
FRIDAY MORNING LENDING SOME UNCERTAINTY TO MAGNITUDE OF AFTERNOON
INSTABILITY. HOWEVER...STRONG MID/UPPER LEVEL FORCING WILL LIKELY
COMPENSATE FOR LIMITED INSTABILITY AND PROMOTE WIDESRPEAD SHOWERS
AND THUNDERSTORMS IN THE AFTERNOON/EARLY EVENING FRIDAY. AT THIS
FORECAST DISTANCE HAVE MAINTAINED SHRA/VCTS MENTION FOR BOTH
TERMINALS BUT FUTURE FORECASTS WILL LIKELY NEED TO RESOLVE A
PERIOD FOR TS INCLUSION.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

UPDATE...MARSILI
SYNOPSIS...MARSILI
SHORT TERM...STEINWEDEL
LONG TERM...JT
AVIATION...MARSILI


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AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 225 PM EDT WED SEP 18 2013

.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW

&&

.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013

A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.

&&

.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013

INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 330 AM EDT WED SEP 18 2013

MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.

SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013

FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.

MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.

TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

ISSUED AT 220 PM EDT WED SEP 18 2013

DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES.

GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE
APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG
SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY
FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD.

AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT
WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS
RETURN FLOW BEGINS.

&&

.AVIATION /DISCUSSION FOR THE 181800Z TAFS/...

ISSUED AT 1223 PM EDT WED SEP 18 2013

VFR CONDITIONS EXPECTED THIS AFTERNOON AND EVENING. MVFR TO IFR
CONDITIONS WILL BE POSSIBLE LATE TONIGHT. A RETURN TO VFR IS
EXPECTED LATE ON THURSDAY MORNING.

ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS AS A WEAK RIDGE ALOFT ALLOWS SEVERAL WEAK...ILL-DEFINED SHORT
WAVES TO PASS ACROSS THE TAF SITES. FORECAST SOUNDINGS SHOW
LIMITED INSTABILITY...HOWEVER THE LOWER LEVELS SHOW AMPLE
MOISTURE. FURTHERMORE BROAD ISENTROPIC LIFT REMAINS IN PLACE
ACROSS THE REGION...PROVIDING HINTS OF LIFT. HOWEVER...NO ONE
FEATURE IS PREVALENT ENOUGH TO GRAB ONTO TO TIME ANY PRECIP MENTION.

THUS BASED UPON RADAR TRENDS...ISOLATED SHRA/TSRA OVER ILLINOIS
MAY REACH HUF AND BMG THIS AFTERNOON...HOWEVER AS HEATING IS LOST
THIS EVENING...OVERALL COVERAGE OF PRECIPITATION SHOULD DIMINISH.
MODELS HINT AT LOWERING CIGS AND VISIBILITIES DIURNALLY TONIGHT
AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. MODELS ONCE
AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE
THURSDAY MORNING...HOWEVER...CONFIDENCE IN THESE WEAK FEATURES
REMAIN LOW.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....PUMA
AVIATION...JP

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AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 1234 PM EDT WED SEP 18 2013

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW

&&

.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013

A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.

&&

.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013

INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 330 AM EDT WED SEP 18 2013

MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.

SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013

FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.

MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.

TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EDT WED SEP 18 2013

ENSEMBLES INDICATE A RATHER STRONG UPPER TROUGH WILL BE MOVING
THROUGH THE GREAT LAKES ON SATURDAY. ALTHOUGH IT APPEARS THAT THE
ASSOCIATED COLD FRONT WILL BE EAST OF THE AREA BY SATURDAY...SEVERAL
ENSEMBLES CUTOFF THE SOUTHERN PORTION OF THE TROUGH OVER THE OHIO
VALLEY ON SATURDAY...WITH THIS CUTOFF EVENTUALLY SINKING INTO THE
SOUTHEAST PORTIONS OF THE COUNTRY BY EARLY NEXT WEEK. THIS MAY
PROLONG THE PRECIPITATION THREAT INTO SATURDAY. WILL GO WITH CHANCE
POPS ON SATURDAY TO COVER THIS.

OTHERWISE...UPPER RIDGING EXPECTED TO BUILD ACROSS THE AREA THROUGH
THE MIDDLE OF NEXT WEEK AS LONG WAVE TROUGHING DEVELOPS OVER THE
WEST. WILL GO DRY AFTER SATURDAY.

&&

.AVIATION /DISCUSSION FOR THE 181800Z TAFS/...

ISSUED AT 1223 PM EDT WED SEP 18 2013

VFR CONDITIONS EXPECTED THIS AFTERNOON AND EVENING. MVFR TO IFR
CONDITIONS WILL BE POSSIBLE LATE TONIGHT. A RETURN TO VFR IS
EXPECTED LATE ON THURSDAY MORNING.

ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS AS A WEAK RIDGE ALOFT ALLOWS SEVERAL WEAK...ILL-DEFINED SHORT
WAVES TO PASS ACROSS THE TAF SITES. FORECAST SOUNDINGS SHOW
LIMITED INSTABILITY...HOWEVER THE LOWER LEVELS SHOW AMPLE
MOISTURE. FURTHERMORE BROAD ISENTROPIC LIFT REMAINS IN PLACE
ACROSS THE REGION...PROVIDING HINTS OF LIFT. HOWEVER...NO ONE
FEATURE IS PREVALENT ENOUGH TO GRAB ONTO TO TIME ANY PRECIP MENTION.

THUS BASED UPON RADAR TRENDS...ISOLATED SHRA/TSRA OVER ILLINOIS
MAY REACH HUF AND BMG THIS AFTERNOON...HOWEVER AS HEATING IS LOST
THIS EVENING...OVERALL COVERAGE OF PRECIPITATION SHOULD DIMINISH.
MODELS HINT AT LOWERING CIGS AND VISIBILITIES DIURNALLY TONIGHT
AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. MODELS ONCE
AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE
THURSDAY MORNING...HOWEVER...CONFIDENCE IN THESE WEAK FEATURES
REMAIN LOW.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JP

VISIT US AT HTTP://WWW.WEATHER.GOV/IND

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AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 1032 AM EDT WED SEP 18 2013

.UPDATE...
AVIATION SECTION UPDATED

&&

.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013

A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.

&&

.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013

INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 330 AM EDT WED SEP 18 2013

MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.

SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013

FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.

MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.

TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EDT WED SEP 18 2013

ENSEMBLES INDICATE A RATHER STRONG UPPER TROUGH WILL BE MOVING
THROUGH THE GREAT LAKES ON SATURDAY. ALTHOUGH IT APPEARS THAT THE
ASSOCIATED COLD FRONT WILL BE EAST OF THE AREA BY SATURDAY...SEVERAL
ENSEMBLES CUTOFF THE SOUTHERN PORTION OF THE TROUGH OVER THE OHIO
VALLEY ON SATURDAY...WITH THIS CUTOFF EVENTUALLY SINKING INTO THE
SOUTHEAST PORTIONS OF THE COUNTRY BY EARLY NEXT WEEK. THIS MAY
PROLONG THE PRECIPITATION THREAT INTO SATURDAY. WILL GO WITH CHANCE
POPS ON SATURDAY TO COVER THIS.

OTHERWISE...UPPER RIDGING EXPECTED TO BUILD ACROSS THE AREA THROUGH
THE MIDDLE OF NEXT WEEK AS LONG WAVE TROUGHING DEVELOPS OVER THE
WEST. WILL GO DRY AFTER SATURDAY.

&&

.AVIATION /DISCUSSION FOR THE 181500Z IN TAF UPDATE/...

ONGOING TAFS IN PRETTY GOOD SHAPE. RADAR TRENDS SHOW AN AREA OF
SHRA OVER SW INDIANA...POISED TO BRUSH HUF AND PUSH ACROSS THE BMG
TAF SITES. ONGOING TEMPS GROUPS HAND THAT WELL. AT THE MOMENT NO
THUNDER APPEARS PRESENT AND WILL KEEP THE TSRA MENTION OUT OF THE
FORECAST.

PREVIOUS DISCUSSION BELOW

/DISCUSSION FOR THE 181200Z TAFS/...
ISSUED AT 629 AM EDT WED SEP 18 2013

UPPER WAVE CURRENTLY MOVING THROUGH SOUTHERN ILLINOIS IS EXPECTED TO
MOVE ACROSS SOUTHERN INDIANA LATER TODAY AND GRADUALLY WEAKEN BASED
ON MODEL DATA. ALTHOUGH THIS FEATURE EXPECTED TO WEAKEN...THERE IS
CURRENTLY QUITE OF BIT OF RAIN ASSOCIATED WITH THIS FEATURE. AS A
RESULT...THINK THE CHANCES ARE PRETTY GOOD FOR A PERIOD OF LIGHT
RAIN...MAINLY IN THE KHUF/KBMG AREAS ROUGHLY 181300Z-181800Z. LOWER
CHANCES AT KIND/KLAF. RAIN SHOULD BE LIGHT ENOUGH THAT IT SHOULDN/T
RESTRICT VISIBILITIES THAT MUCH...ALTHOUGH SOME CEILINGS AROUND 040
POSSIBLE NEAR THE RAIN AREAS. CONVECTIVE PARAMETERS TODAY NOT
IMPRESSIVE IN THE IMMEDIATE AREA...BUT ARE MORE FAVORABLE THIS
AFTERNOON TO THE SOUTHWEST OF KHUF/KBMG.

OTHERWISE...CEILINGS GENERALLY ABOVE 050 TODAY WITH NO WIND ISSUES
EXPECTED AT THE TAF SITES THROUGH 190000Z.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JAS/JP

VISIT US AT HTTP://WWW.WEATHER.GOV/IND

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AREA FORECAST DISCUSSION

NWS INDIANAPOLIS IN

 942 AM EDT WED SEP 18 2013

.UPDATE...

THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 330 AM EDT WED SEP 18 2013

A COLD FRONT WILL DROP SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY
NIGHT. THE FRONT WILL INTERACT WITH WARM...MOIST AND UNSTABLE AIR
WHICH WILL RESULT IN THUNDERSTORM CHANCES STARTING TODAY. THE BEST
CHANCES WILL BE FRIDAY AND FRIDAY NIGHT AS THE FRONT GETS CLOSER.
THE SOUTHERLY FLOW WILL ALSO RESULT IN ABOVE NORMAL
TEMPERATURES...MOSTLY IN THE 80S. THEN...DRY WEATHER WILL RETURN BY
SATURDAY AS HIGH PRESSURE SETTLES EAST ACROSS THE GREAT LAKES WITH
COOLER TEMPERATURES IN THE 70S FOR AFTERNOON HIGHS.

&&

.NEAR TERM /TODAY/...
ISSUED AT 942 AM EDT WED SEP 18 2013

INTRODUCED LIKELIES INTO THE SOUTHWESTERN FORECAST AREA THROUGH
MIDDAY FOR THE AREA OF SHOWERS PUSHING INTO THAT AREA. HRRR TAKES
THIS THROUGH THE SOUTHWEST/SOUTH CENTRAL AREA AS IT WEAKENS LATER
THIS MORNING. AT LEAST A STRIKE OR TWO DETECTED SO WILL CONTINUE
ISOLATED THUNDER MENTION. ALSO REDUCED MAX TEMPS IN THAT AREA
OWING TO INFLUENCE OF RAIN COOLED AIR DURING WHAT WOULD ORDINARILY
BE BEST TIME FOR HEATING. PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 330 AM EDT WED SEP 18 2013

MAIN FOCUS TODAY WILL BE ON POPS. RADAR WAS SHOWING A GROUP OF
SHOWERS MOVING EAST AND NORTHEAST ACROSS NORTHWESTERN INDIANA AND
ARE ASSOCIATED WITH A WEAK WAVE ALOFT IN OTHERWISE MODEST ZONAL
FLOW. IN ADDITION...THERE WAS SOME ACTIVITY ACROSS SOUTHERN ILLINOIS
AND ALSO NEAR ST. LOUIS ASSOCIATED WITH ANOTHER WEAK WAVE THAT WILL
MOVE EAST ACROSS SOUTH CENTRAL INDIANA THIS MORNING. WEAK ISENTROPIC
LIFT WILL CONTINUE ALL THE WHILE...AND MODEL SOUNDINGS WERE
INDICATING DEEPENING MOISTURE. THE 05Z RAPID REFRESH WAS GOING
BONKERS WITH WIDESPREAD RAIN THIS MORNING...BLOWING UP THE SOUTHERN
ILLINOIS SHOWERS. THAT BEING SAID...DID RAISE POPS TO 30 PERCENT OR
MORE EXCEPT ACROSS OUR FAR EAST DO MAINLY TO RADAR TRENDS.
INSTABILITY IS PROGGED TO BE WEAK OR ABSENT TODAY...SO ONLY
MENTIONED ISOLATED THUNDER.

SHOULD BE DECENT CLOUD COVER TODAY...SO PREFER AT OR BELOW CONSALL
AND ALLBLEND.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 330 AM EDT WED SEP 18 2013

FOCUS WILL CONTINUE TO BE ON POPS THROUGH THE ENTIRE SHORT TERM.

MODELS ARE SIMILAR IN BRINGING A COLD FRONT SOUTHEAST ACROSS CENTRAL
INDIANA FRIDAY NIGHT AS A VIGOROUS UPPER TROUGH PROGRESSES EAST
ACROSS SOUTHERN CANADA. UPPER RIDGE WILL SETTLE ACROSS CENTRAL
INDIANA THURSDAY...WITH RETURN FLOW ACROSS THE OHIO VALLEY AROUND
EAST COAST HIGH PRESSURE. THIS WILL RESULT A VERY UNSTABLE
ATMOSPHERE ON THURSDAY WITH CAPES ABOVE 2000 J/KG. STILL...PLENTY OF
INSTABILITY THROUGH THE ENTIRE EXTENDED FOR THUNDER. WITH ONLY WEAK
SYNOPTIC FORCING...WILL ONLY GO WITH SMALL POPS UNTIL FRIDAY AFTER
THE UPPER RIDGE PASSES AND THE COLD FRONT AND UPPER TROUGH GET
CLOSER. THEN...LIKELY POPS FROM CONSALL...ALLBLEND AND MOS BLEND
LOOK GOOD AS MODEL UPWARD VERTICAL MOTION AND QPF PROGS SUGGEST
LINEAR CONVECTION LATE FRIDAY AFTERNOON AND NIGHT. WOULD NOT RULE
OUT STRONG OR EVEN ISOLATED SEVERE STORMS AS FRIDAY AND FRIDAY NIGHT.

TEMPERATURES WITH THE CLOUD COVER WILL BE TRICKY...BUT OVERALL ALL
BLEND LOOKS DECENT AND MATCHES UP WELL WITH ADJACENT OFFICES.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 330 AM EDT WED SEP 18 2013

ENSEMBLES INDICATE A RATHER STRONG UPPER TROUGH WILL BE MOVING
THROUGH THE GREAT LAKES ON SATURDAY. ALTHOUGH IT APPEARS THAT THE
ASSOCIATED COLD FRONT WILL BE EAST OF THE AREA BY SATURDAY...SEVERAL
ENSEMBLES CUTOFF THE SOUTHERN PORTION OF THE TROUGH OVER THE OHIO
VALLEY ON SATURDAY...WITH THIS CUTOFF EVENTUALLY SINKING INTO THE
SOUTHEAST PORTIONS OF THE COUNTRY BY EARLY NEXT WEEK. THIS MAY
PROLONG THE PRECIPITATION THREAT INTO SATURDAY. WILL GO WITH CHANCE
POPS ON SATURDAY TO COVER THIS.

OTHERWISE...UPPER RIDGING EXPECTED TO BUILD ACROSS THE AREA THROUGH
THE MIDDLE OF NEXT WEEK AS LONG WAVE TROUGHING DEVELOPS OVER THE
WEST. WILL GO DRY AFTER SATURDAY.

&&

.AVIATION /DISCUSSION FOR THE 181200Z TAFS/...
ISSUED AT 629 AM EDT WED SEP 18 2013

UPPER WAVE CURRENTLY MOVING THROUGH SOUTHERN ILLINOIS IS EXPECTED TO
MOVE ACROSS SOUTHERN INDIANA LATER TODAY AND GRADUALLY WEAKEN BASED
ON MODEL DATA. ALTHOUGH THIS FEATURE EXPECTED TO WEAKEN...THERE IS
CURRENTLY QUITE OF BIT OF RAIN ASSOCIATED WITH THIS FEATURE. AS A
RESULT...THINK THE CHANCES ARE PRETTY GOOD FOR A PERIOD OF LIGHT
RAIN...MAINLY IN THE KHUF/KBMG AREAS ROUGHLY 181300Z-181800Z. LOWER
CHANCES AT KIND/KLAF. RAIN SHOULD BE LIGHT ENOUGH THAT IT SHOULDN/T
RESTRICT VISIBILITIES THAT MUCH...ALTHOUGH SOME CEILINGS AROUND 040
POSSIBLE NEAR THE RAIN AREAS. CONVECTIVE PARAMETERS TODAY NOT
IMPRESSIVE IN THE IMMEDIATE AREA...BUT ARE MORE FAVORABLE THIS
AFTERNOON TO THE SOUTHWEST OF KHUF/KBMG.

OTHERWISE...CEILINGS GENERALLY ABOVE 050 TODAY WITH NO WIND ISSUES
EXPECTED AT THE TAF SITES THROUGH 190000Z.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...MK
NEAR TERM...MK/NIELD
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JAS

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AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 952 PM CDT Thu Sep 19 2013

...UPDATE TO SYNOPSIS...

.SYNOPSIS...
ISSUED AT 950 PM CDT THU SEP 19 2013

Water vapor imagery and 00Z upper air analysis indicate an upper
level trough of low pressure drifting eastward across the Dakotas.
Meanwhile, upper level ridging is moving eastward across the
Intermountain West. Near the surface, a cold front extends from
the Texas Panhandle northeast into eastern Kansas. Cooler and
drier air has filtered south into western Kansas lowering surface
dewpoints primarily down into the 50s(F) with a few mid to upper
40s(F) closer to the Colorado border.

&&

.SHORT TERM...(This evening through Friday)
ISSUED AT 145 PM CDT THU SEP 19 2013

Based on 18z surface analysis the surface cold front was
progressing across western Kansas slightly quicker than what the
12z GFS and 12z NAM suggested. The latest HRRR and RAP seems to be
tracking the front a little better earlier this afternoon so will
follow these models for the frontal location between 21z and 00z.
Convection is expected to begin to initiate near this boundary
late day given the afternoon instability progged and improving
upper level dynamic from the left entrance region of an weak upper
level jet crossing western Oklahoma. The current distribution of
precipitation chances across south central Kansas still looks on
track so other than adjusting the location of the front, no major
adjustments to the previous forecast is anticipated late today and
early tonight. SPC mesoanalysis indicating better 0-6km shear late
today so at this time can not rule the chance of a few
thunderstorms near the Oklahoma border. Quarter size hail, gusty
winds and periods of heavy rainfall currently appear to be the
main hazard late today.

Convection across south central Kansas and near the Oklahoma
border after sunset will taper off towards midnight and skies are
expected to begin to clear from north to south. Lows tonight will
be cooler than the past few nights and based on expected 09z to
12z dewpoints will keep lows mainly in the 50s.

High pressure at the surface will build into western Kansas on
Friday as an upper level ridge builds into the western high plains
from the west. The highs on Friday are expected to climb only into
the mid to upper 70s given that both the NAM and GFS suggest a 3c-
6c decrease in 925mb-850mb temperature from 00z Thursday to 00z
Friday.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 222 PM CDT THU SEP 19 2013

Mostly clear skies and dry conditions are anticipated Friday night
through Sunday morning as an upper level ridge moves over the
Central Plains, mid levels of the atmosphere remain dry, and a dome
of high pressure slides southeast of the area. The only exception to
this will be the possibility of a few cumulus clouds around peak
heating. Winds will generally be from the northeast Friday night
shifting to more of a southerly direction Saturday into Sunday
morning. Meanwhile, an upper level shortwave will be moving through
the Western United States Saturday then into the Central Rockies
Sunday. Mid to upper level moisture will be on the increase during
the day Sunday allowing for a few clouds to form. This shortwave
will also help push a cold front through the area Sunday night. A
few thunderstorms will be possible along and ahead of this front
with winds shifting to more of a southerly direction behind it. Cold
air advection will be short lived with this front as winds shift
back to a southerly direction Monday night through Wednesday. Flow
aloft becomes more zonal (west to east) Monday night through Tuesday
then more of a southwest direction Wednesday as the next shortwave
digs into the Intermountain West. Mostly clear skies and dry
conditions are expected over Western Kansas during this timeframe
with lee troughing strengthening across eastern Colorado.

Seasonable temperatures are expected Saturday with highs around 80
degrees and lows Saturday and Sunday morning in the 50s. Highs are
then expected to reach into the lower 80s Sunday and Monday with mid
80s Tuesday and Wednesday. Lows are forecasted to range from the
upper 50s to mid 60s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 706 PM CDT THU SEP 19 2013

A surface cold front has extended to the south of Pratt and KDDC
into extreme nw Oklahoma early this evening. Surface winds at the
local terminals will remain northeast for the rest of these terminal
forecasts as the region will remain in the post frontal airmass. Any
could cover is generally mid level and decreasing with time, and VFR
category conditions are expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  55  77  51  80 /   0   0   0   0
GCK  53  75  51  81 /   0   0   0   0
EHA  52  75  53  81 /  10   0   0   0
LBL  55  77  52  82 /  20   0   0   0
HYS  52  75  51  81 /   0   0   0   0
P28  60  78  53  80 /  60   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...JJohnson
SHORT TERM...Burgert
LONG TERM...Hovorka_42
AVIATION...Russell







AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 709 PM CDT Thu Sep 19 2013

...Updated for the Aviation discussion...

.SYNOPSIS...
ISSUED AT 1206 PM CDT THU SEP 19 2013

At 12z Thursday a -18c 500mb trough was located over the northern
Rockies with a 300mb jet streak extending from the based of this
upper trough into southern Manitoba. Across the panhandle of Texas a
40-50kt jet was observed with the left exit region of this jet
steak located near the Oklahoma panhandle. this related well to
some early morning convection which developed near a surface
trough of low pressure that extended from the panhandle of
Oklahoma into north central Kansas. A surface cold front at 12z
extended from eastern Nebraska, across northwest Kansas into east
central Colorado.

&&

.SHORT TERM...(This evening through Friday)
ISSUED AT 145 PM CDT THU SEP 19 2013

Based on 18z surface analysis the surface cold front was
progressing across western Kansas slightly quicker than what the
12z GFS and 12z NAM suggested. The latest HRRR and RAP seems to be
tracking the front a little better earlier this afternoon so will
follow these models for the frontal location between 21z and 00z.
Convection is expected to begin to initiate near this boundary
late day given the afternoon instability progged and improving
upper level dynamic from the left entrance region of an weak upper
level jet crossing western Oklahoma. The current distribution of
precipitation chances across south central Kansas still looks on
track so other than adjusting the location of the front, no major
adjustments to the previous forecast is anticipated late today and
early tonight. SPC mesoanalysis indicating better 0-6km shear late
today so at this time can not rule the chance of a few
thunderstorms near the Oklahoma border. Quarter size hail, gusty
winds and periods of heavy rainfall currently appear to be the
main hazard late today.

Convection across south central Kansas and near the Oklahoma
border after sunset will taper off towards midnight and skies are
expected to begin to clear from north to south. Lows tonight will
be cooler than the past few nights and based on expected 09z to
12z dewpoints will keep lows mainly in the 50s.

High pressure at the surface will build into western Kansas on
Friday as an upper level ridge builds into the western high plains
from the west. The highs on Friday are expected to climb only into
the mid to upper 70s given that both the NAM and GFS suggest a 3c-
6c decrease in 925mb-850mb temperature from 00z Thursday to 00z
Friday.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 222 PM CDT THU SEP 19 2013

Mostly clear skies and dry conditions are anticipated Friday night
through Sunday morning as an upper level ridge moves over the
Central Plains, mid levels of the atmosphere remain dry, and a dome
of high pressure slides southeast of the area. The only exception to
this will be the possibility of a few cumulus clouds around peak
heating. Winds will generally be from the northeast Friday night
shifting to more of a southerly direction Saturday into Sunday
morning. Meanwhile, an upper level shortwave will be moving through
the Western United States Saturday then into the Central Rockies
Sunday. Mid to upper level moisture will be on the increase during
the day Sunday allowing for a few clouds to form. This shortwave
will also help push a cold front through the area Sunday night. A
few thunderstorms will be possible along and ahead of this front
with winds shifting to more of a southerly direction behind it. Cold
air advection will be short lived with this front as winds shift
back to a southerly direction Monday night through Wednesday. Flow
aloft becomes more zonal (west to east) Monday night through Tuesday
then more of a southwest direction Wednesday as the next shortwave
digs into the Intermountain West. Mostly clear skies and dry
conditions are expected over Western Kansas during this timeframe
with lee troughing strengthening across eastern Colorado.

Seasonable temperatures are expected Saturday with highs around 80
degrees and lows Saturday and Sunday morning in the 50s. Highs are
then expected to reach into the lower 80s Sunday and Monday with mid
80s Tuesday and Wednesday. Lows are forecasted to range from the
upper 50s to mid 60s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 706 PM CDT THU SEP 19 2013

A surface cold front has extended to the south of Pratt and KDDC
into extreme nw Oklahoma early this evening. Surface winds at the
local terminals will remain northeast for the rest of these terminal
forecasts as the region will remain in the post frontal airmass. Any
could cover is generally mid level and decreasing with time, and VFR
category conditions are expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  55  77  51  80 /  20   0   0   0
GCK  53  76  51  81 /  10   0   0   0
EHA  52  75  53  81 /  20   0   0   0
LBL  55  78  52  82 /  40   0   0   0
HYS  52  75  51  81 /  10   0   0   0
P28  60  80  53  80 /  80  10   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...Burgert
SHORT TERM...Burgert
LONG TERM...Hovorka_42
AVIATION...Russell







AREA FORECAST DISCUSSION

NWS PADUCAH KY

 230 PM CDT Wed Sep 18 2013

.SHORT TERM /Tonight through Friday night/...
ISSUED AT 230 PM CDT WED SEP 18 2013

The showers and isolated thunderstorms that occurred this morning
have all but dissipated by mid afternoon. Partial clearing will
continue to spread slowly east. The trend toward low and mid level
drying is indicated by RAP and nam model soundings. This drying
appears to be in response to a gradual rebuilding of the 500 mb
ridge that was flattened by a weak impulse this morning.

Through Thursday...the mid level ridge will continue to slowly build
over our region. This should continue to suppress most convection
over the Lower Ohio and Mid Mississippi Valleys. Will keep slight
chance pops during the peak heating hours from roughly 18z to 00z to
account for isolated diurnally driven storms.

A rather strong cold front will approach from the northwest on
Thursday night...reaching southern Illinois and southeast Missouri
on Friday. The front will continue moving southeast across western
Kentucky and southwest Indiana on Friday evening. The 09z sref
timing looks reasonable. A deepening upper trough will enhance lift
along the frontal zone...and deep layer moisture will be high for
this time of year /sref precip water values about 1.9 inches/. Looks
like the first widespread significant rainfall of the month will
occur. Storm total qpf should be at least one half inch...with some
1 inch amounts likely in heavier convection. Severe weather
potential will depend on how much sunshine and diurnal heating takes
place ahead of the front. Isolated severe convection is currently
forecast by SPC /see day 3 outlook/.

South to southwest low level flow will keep unseasonably warm and
humid conditions in place through Friday. The nam continues to have
problems with too much moisture in the model...as shown in its high
pops and abundant cloudiness. The warmer gfs mos highs look better
for Thursday.

.LONG TERM /Saturday through Wednesday/...
ISSUED AT 230 PM CDT WED SEP 18 2013

Main issue in the extended looks to be with how quickly an upper
level trof will move east out of the region over the weekend. Models
seem to be trending toward a less progressive solution in this
respect. Both the operational GFS and ECMWF not suggest showers will
linger into Saturday along and south of the Ohio River, east of the
H50 trof axis. Will bump up precip chances on Sat into the 40 to 50
percent range over much of the Pennyrile region of western KY.

Otherwise, the most noticeable change over the weekend will be
another transition to much cooler and less humid conditions. Highs
both Saturday and Sunday will likely stay down in the 70s, with lows
Sat night mostly in the 50 to 55 degree range.

As we head into next week, it now appears as though an Omega
Blocking pattern will become established along the MS River Valley.
This should keep things quite dry across our region, with sunny,
warm afternoons and cool nights. Temperatures will warm a touch each
day, and most locations will likely be back into the middle 80s by
Wednesday afternoon. Humidity levels should stay low though.

&&

.AVIATION...
ISSUED AT 1237 PM CDT WED SEP 18 2013

A weak disturbance in the mid levels of the atmosphere will progress
east of the region this afternoon. In the wake of the
disturbance...clearing has occurred over se Missouri. This clearing
will spread across the kpah area early this afternoon. Where rain
saturated the low levels this morning around kevv and kowb...mvfr
cigs are likely to persist most or all afternoon. All sites will
lose their low clouds around sunset. Mainly just mid level clouds
are forecast for the remainder of the taf period. Winds will remain
around 5 knots all night...which should preclude vsby problems due
to haze or fog.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

SHORT TERM...MY
LONG TERM...GM
AVIATION...MY









AREA FORECAST DISCUSSION

NWS JACKSON KY

 127 AM EDT WED SEP 18 2013

.UPDATE...
ISSUED AT 126 AM EDT WED SEP 18 2013

THE FORECAST WAS PRETTY MUCH ON TRACK SO FAR TONIGHT. HOURLY
TEMPERATURES AND DEWPOINTS HAVE BEEN RUNNING PRETTY CLOSE TO THE
FORECAST VALUES. COVERAGE OF CLOUD COVER AND FOG HAS ALSO BEEN ON THE
MONEY COMPARED TO THE FORECAST. AS USUAL...OBSERVATIONAL DATA WAS
INGESTED INTO THE HOURLY GRIDS TO ESTABLISH SOME NEW TRENDS. ASIDE
FROM THAT...NO UPDATE TO THE FORECAST IS PLANNED AT THIS TIME.

UPDATE ISSUED AT 1055 PM EDT TUE SEP 17 2013

HAVE UPDATED THE FORECAST FOR THE NEAR TERM SKY/T/TD GRIDS BASED ON
CURRENT OBS AND TRENDS. THE 00Z NAM12 AND LATEST HRRR STILL KEEP MOST
OF THE SHOWERS WEST OF THE AREA THROUGH 12Z. UPDATES HAVE BEEN SENT
TO THE NDFD AND WEB SERVERS.

UPDATE ISSUED AT 745 PM EDT TUE SEP 17 2013

23Z SFC ANALYSIS SHOWS HIGH PRESSURE RETREATING OFF TO THE EAST IN
THE FACE OF APPROACHING LOW PRESSURE. THIS TRANSITION WILL BRING
LOWER CIGS TO EAST KENTUCKY TOWARD DAWN ALONG WITH A SMALL CHANCE OF
SHOWERS IN THE WESTERN PARTS OF THE AREA. THESE CLOUDS SHOULD LIMIT
THE FOG FORMATION TO THE DEEPER VALLEYS GENERALLY EAST OF JKL.
LIKEWISE...EXPECT A RIDGE TO VALLEY TEMPERATURE SPLIT OVER THE
EASTERN PARTS OF THE CWA WITH MILDER TEMPERATURES AND HIGHER
DEWPOINTS SEEN ELSEWHERE. HAVE UPDATED THE FORECAST GRIDS FOR THESE
THOUGHTS...ESSENTIALLY TWEAKING LOW TEMPS...ADJUSTING THE DIURNAL
CURVE...AND PULLING POPS WESTWARD THROUGH SUNRISE PER THE LATEST
NAM12 AND HRRR. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS...ALONG WITH A FRESHENED SET OF ZONES.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 250 PM EDT TUE SEP 17 2013

THE MODELS ARE IN PRETTY GOOD AGREEMENT. HIGH PRESSURE BUILD IN
BEHIND THE FRONT THAT MOVED THROUGH THE AREA YESTERDAY. THIS FRONT
WILL MOVE BACK TO THE NORTH AS A WARM FRONT THIS EVENING AND ALONG
WITH THE ISENTROPIC LIFT...WILL BE ABLE TO PRODUCE SOME ISOLATED TO
SCATTERED LIGHT RAIN SHOWERS LATE TONIGHT AND TOMORROW. THE FRONT AND
THE RAIN WILL CONTINUE TO MOVE TO THE NORTHEAST. THIS WILL ALLOW THE
TEMPS TO WARM UP AND FOR THE HUMIDITY TO INCREASE. FOR
TEMPERATURES...USED THE MODEL BLEND AND THE BUMPED THEM UP A COUPLE
OF DEGREES FOR THE HIGHS ON WEDNESDAY. THIS WAS A BIT OF A COMPROMISE
BETWEEN THE MOS AND THE RAW MODEL OUTPUT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 250 PM EDT TUE SEP 17 2013

HIGH PRESSURE WILL BE FIRMLY IN CONTROL AT THE START OF THE PERIOD.
WHILE SOME MEAGER INSTABILITY WILL DEVELOP THURSDAY AND FRIDAY
AFTERNOONS...NOT MUCH OF A TRIGGER TO REALLY GET ANYTHING GOING. IN
FACT...INSTABILITY IS SO MEAGER...OPTING TO TREND POPS DOWNWARD BOTH
DAYS. NAM IS THE OUTLIER WITH A BIT MORE INSTABILITY...BUT ALSO
APPEARS TO BE BRINGING HIGHER DEWPOINTS IN MUCH TOO QUICK...SO HAVE
OPTED TO DISCOUNT THIS MODEL FOR THE TIME BEING.

MODELS CONTINUE THE TREND OF SLOWING DOWN THE COLD FRONT FOR THE
UPCOMING WEEKEND. IT NOW LOOKS LIKE THE FRONT SHOULD CROSS EASTERN
KENTUCKY FROM LATE FRIDAY NIGHT THROUGH SATURDAY. WILL CONTINUE THE
HIGH POPS DURING THIS PERIOD. HAVE TRENDED THE THUNDER POTENTIAL
DOWNWARD GIVEN THE LACK OF ANY SUBSTANTIAL INSTABILITY. SOME
ELEVATED THUNDER MAY BE POSSIBLE AT TIMES...BUT SURFACE INSTABILITY
NEVER GETS THAT STRONG...EVEN INTO SATURDAY AFTERNOON. FRONT MAY
LINGER ACROSS THE SOUTHEAST INTO SUNDAY MORNING BEFORE FINALLY
EXITING BY SUNDAY AFTERNOON...ALLOWING FOR DRY WEATHER TO END THE
WEEKEND. WITH HIGH PRESSURE BUILDING IN SUNDAY NIGHT...A QUIET START
TO THE NEW WEEK IS ANTICIPATED. HIGHS THURSDAY AND FRIDAY WILL
RETURN TO SLIGHTLY ABOVE NORMAL WITH PLENTY OF SUNSHINE...BUT WILL
TREND BACK BELOW NORMAL FOR THE WEEKEND INTO EARLY NEXT WEEK AS
COOLER WEATHER SETTLES IN BEHIND THE COLD FRONT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 126 AM EDT WED SEP 18 2013

VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGHOUT THE TAF PERIOD.
VALLEY FOG SHOULD BE VERY MINIMAL TONIGHT...ASIDE FROM FAR EASTERN
PARTS OF THE AREA...DUE TO STEADILY INCREASING CLOUD COVER AND THE
FACT THAT WINDS WILL NOT LAY AS MUCH TONIGHT AS IN PREVIOUS NIGHTS.
LIGHT SHOWERS MAY MOVE INTO THE AREA TOWARD DAWN FROM THE WEST
GENERALLY CAUSING CIGS TO DROP DOWN TO AROUND 4K FT. HOWEVER...CIGS
AND VSBY ARE EXPECTED TO REMAIN VFR THROUGHOUT THE PERIOD. HAVE
INCLUDED VCSH FOR THE DAYTIME HOURS. WINDS WILL BE LIGHT AND VARIABLE
THROUGHOUT THE FORECAST.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...AR
SHORT TERM...JJ
LONG TERM...KAS
AVIATION...AR







AREA FORECAST DISCUSSION

NWS GAYLORD MI

 1146 PM EDT THU SEP 19 2013

.SYNOPSIS...
ISSUED AT 407 PM EDT THU SEP 19 2013

IT WILL BE WARM AND HUMID ACROSS NORTHERN MICHIGAN THROUGH
FRIDAY...AHEAD OF A STRONG COLD FRONT PUSHING ACROSS THE WESTERN
LAKES. THIS BOUNDARY WILL GENERATE SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS THROUGH FRIDAY...BEFORE SEASONAL CONDITIONS AND SOME
LAKE INDUCED RAINS RETURN TO NORTHERN MICHIGAN TO START THE WEEKEND.

HIGH PRESSURE WILL SETTLE INTO THE REGION SUNDAY AND MONDAY. THIS
PATTERN WILL GENERATE AN EXTENDED STRETCH OF DRY AND COMFORTABLE
WEATHER ACROSS THE GREAT LAKES FOR THE FIRST OFFICIAL WEEK OF FALL.

&&

.UPDATE...
ISSUED AT 1046 PM EDT THU SEP 19 2013

SEVERAL AREAS OF CONVECTION HAVE DEVELOPED OVER THE PAST FEW HOURS
ACROSS NRN LWR MICHIGAN...MAINLY SOUTH OF M-32...AS DEEPER
MOISTURE/850 MB THETA E RIDGING BEGINS TO SURGE INTO THE AREA ON
THE NOSE OF A STRENGTHENING LOW LEVEL JET. OVERALL INTENSITY OF
STORMS HAS BEEN RELATIVELY WEAK...AND ORGANIZATION HAS BEEN
LIMITED WELL AHEAD OF THE APPROACHING COLD FRONT. ADDITIONAL
CONVECTION CONTINUES TO DEVELOP ALONG AND AHEAD OF THE FRONT FROM
CENTRAL MISSOURI TO NW ILLINOIS TO SRN AND ERN WISCONSIN AND WRN
UPR MICHIGAN. THE FRONT ITSELF WILL STAY WEST OF OUR CWA
OVERNIGHT...AND EXPECT WAVES OF SHOWERS AND STORMS WILL CONTINUE
TO IMPACT OUR ENTIRE CWA THRU DAYBREAK. THUS...HAVE INCREASED POPS
FOR THE BALANCE OF THE NIGHT AND INTO EARLY FRIDAY MORNING AS THE
850 MB THETA E RIDGE LEANS INTO THE AREA AND THE LOW LEVEL JET
TAKES AIM DIRECTLY AT OUR CWA THRU THE NIGHT. LIKELY POPS WILL
EVENTUALLY BECOME CATEGORICAL LATE TONIGHT WITH THE ANTICIPATION
OF WIDESPREAD PRECIP SPREAD ACROSS MUCH OF OUR AREA THANKS TO A
POTENT SHORT WAVE RIDING NE AHEAD OF THE 500 MB TROUGH JUST AHEAD
OF THE FRONT.

UPDATE ISSUED AT 725 PM EDT THU SEP 19 2013

TWO RELATIVELY SMALL AREAS OF CONVECTION ARE APPROACHING PORTIONS
OF OUR CWA ATTM AHEAD OF THE APPROACHING COLD FRONT. THE SMALLEST
AND WEAKEST AREA OF CONVECTION IS MOVING NE THRU CENTRAL UPR
MICHIGAN...THE SRN EDGE OF WHICH MAY JUST GRAZE ERN UPR MICHIGAN.
THE SECOND...MORE ORGANIZED AREA IS LIFTING NE OUT OF S CENTRAL
WISCONSIN. TIME EXTRAPOLATION OF THIS LINE OF SHOWERS AND STORMS
BRINGS IT ONSHORE NEAR MBL BY AROUND 03Z...WHICH MATCHES FAIRLY
WELL WITH THE LATEST NAM AND WITH OUR GOING FORECAST. WILL LEAVE A
SMALL CHANCE OF PRECIP IN THE FORECAST IN THE MEANTIME...AND THEN
STEADILY INCREASE POPS FROM WEST TO EAST ACROSS OUR CWA AFTER 03Z.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 407 PM EDT THU SEP 19 2013

WARM...AND AN APPRECIABLY MUGGY AIRMASS...HAS OVERSPREAD THE NORTH
WOODS THIS AFTERNOON. DESPITE THIS...LOSS OF ANY DYNAMICS HAS LED
TO A DRY LATE MORNING AND EARLY AFTERNOON...WITH FOCUS FOR RAINS
SHIFTING WELL TO OUR SOUTH AND WEST. FORMER TIED TO REMNANT COLD
POOL AND LOW LEVEL JET DYNAMICS...WITH THE LATTER FOCUSED ALONG AND
AHEAD OF STRONG SHORTWAVE TROUGH AND ATTENDANT COLD FRONT SUPPORT.
THIS UPSTREAM SYSTEM WILL BE THE IMPETUS FOR ADDITIONAL SHOWERS AND
STORMS HEADING INTO TONIGHT AND FRIDAY. FORECAST CHALLENGES CENTER
ON THESE RAIN POSSIBILITIES.

TOUGH CALL FOR THE REMAINDER OF THIS AFTERNOON INTO EARLY THIS
EVENING. APPEARS FOCUS FOR ANY RAINS WILL BE CENTERED ON LOW LEVEL
CONVERGENCE AXES AND DEVELOPMENT OF SURFACE INSTABILITY. NOTED
CONVERGENCE AXIS DRIFTING SLOWLY NORTH ACROSS THE HIGHLANDS AS OF
THIS WRITING...WELL EVIDENT ON LOCAL RADAR IMAGERY. PER SPS SURFACE
ANALYSIS...BULLSEYE OF 1.5K TO 2.0K ML CAPE HAS DEVELOPED OVER
INTERIOR NORTHERN LOWER MICHIGAN. STILL EVIDENCE OF SOME WEAKISH
CINH TO OVERCOME. REALLY NOT SURE HOW THIS WILL ALL PLAY OUT...BUT
FEEL ABOVE DEFINITELY WORTHY OF KEEPING SOME SHOWER AND STORM
MENTION HEADING INTO EARLY THIS EVENING. FOR WHAT IT`S
WORTH...LATEST RAP SHOWS GOOD STORM DEVELOPMENT HEADING INTO THIS
PERIOD...FOCUSED ACROSS THE INTERIOR HIGHLANDS. RELATIVELY HIGH
PWATS SUPPORT LOCALLY HEAVY RAINS IF/WHERE CONVECTION DEVELOPS.

FOCUS WILL SHIFT TO LOW LEVEL JET DYNAMICS AND APPROACH OF COLD
FRONT FOR SHOWER AND STORM POTENTIAL HEADING INTO TONIGHT. RECENT
TRENDS AND PATTERN RECOGNITION SUPPORT BEST FORCED LOW LEVEL MASS
CONVERGENCE FOCUSED ALONG THE LAKE MICHIGAN CORRIDOR OF NORTHWEST
LOWER AND EASTERN UPPER MICHIGAN AFTER 05Z. MOISTURE REMAINS
GREAT...AND SIMPLE MAGNITUDE OF CONVERGENCE SHOULD BE ENOUGH TO
DRIVE ADDITIONAL ACTIVITY. WILL FOCUS BEST POTENTIAL IN THESE
AREAS...TAPERING TO JUST CHANCY WORDING ACROSS NORTHEAST LOWER
MICHIGAN. ELEVATED NATURE OF STORMS SHOULD PRECLUDE MUCH SEVERE
POTENTIAL. ONCE AGAIN... HOWEVER...GOOD MOISTURE PROFILES SUPPORT
LOCALLY HEAVY RAIN CONCERNS.

SURFACE FRONT LOOKS TO REMAIN AGGRESSIVE HEADING INTO FRIDAY...WITH
LATEST GFS/ECMWF TRENDS DRIVING THE FRONT INTO LAKE HURON THROUGH
EARLY AFTERNOON. PRE-FRONTAL SHOWERS AND STORMS SHOULD
CONTINUE...WITH STRONG UPPER JET SUPPORT AND FGEN DYNAMICS DRIVING
POST-FRONTAL RAINS IMMEDIATELY BEHIND THE SURFACE PORTION OF THE
FRONT. INHERITED GRIDS WELL TRENDED THIS DIRECTION WITH NO
SIGNIFICANT CHANGES NEEDED. DESPITE DECENT KINEMATICS...PLENTY OF
CLOUD COVER AND FASTER TIMING OF FRONT LOOKS TO KEEP SURFACE BASED
INSTABILITY IN CHECK...ONCE AGAIN PRECLUDING MUCH SEVERE WEATHER
POTENTIAL. LATEST SPC GRAPHICS CONCUR...KEEPING SLIGHT CHANCE
WORDING JUST TO OUR SOUTHEAST.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 407 PM EDT THU SEP 19 2013

OVERVIEW AND TRENDS: SUBSTANTIAL LONG WAVE TROUGHING IN PLACE THIS
MORNING FROM THE GULF OF ALASKA DOWN ALONG THE WEST COAST...WITH
DOWNSTREAM RIDGING/WARM AIR ACROSS THE CENTRAL CONUS INTO THE GREAT
LAKES...AND TROUGHING FROM GREENLAND DOWN THROUGH EASTERN CANADA.
LONG WAVE RIDGING IS STILL SLATED TO SLOWLY ADVANCE INTO THE EASTERN
CONUS THROUGH THE WEEKEND...WHILE LARGER SCALE FLOW FLATTENS AND
CONTRACTS TOWARD THE POLE AS WE GO THROUGH NEXT WEEK. SO...NO LONG
LASTING TRANSITION TOWARD COOL FALL WEATHER JUST YET.

ON THE SMALLER SCALE...A COUPLE OF STRONGER SHORT WAVES EMBEDDED
WITHIN THE LARGER SCALE FLOW...ONE PUSHING INTO THE NRN PLAINS THAT
WILL IMPACT US OVER THE NEXT FEW DAYS...AND ANOTHER STRONG WAVE JUST
OFF THE PACIFIC NW COAST THAT WILL PUSH INTO THE PAC NW LATER THIS
WEEKEND. CLOSER TO HOME...LOW PRESSURE STRETCHES FROM SOUTH-CENTRAL
CANADA INTO THE NRN PLAINS...AHEAD OF THE AFOREMENTIONED SHORT WAVE.
ASSOCIATED WARM FRONT STRETCHES DOWN THROUGH THE MIDWEST AND
TRAILING COLD FRONT FROM MINNESOTA INTO THE CENTRAL PLAINS. HAVE
DEALT WITH A COUPLE OF ROUNDS OF SHOWERS AND STORMS WORKING THROUGH
THE REGION ALONG ADVANCING LOW LEVEL MOISTURE AXIS PUSHING INTO THE
REGION NORTH OF THE WARM FRONT.

LATE FRIDAY AFTERNOON THROUGH SATURDAY...SHORT WAVE/THERMAL TROUGH
AXIS ADVANCES INTO THE GREAT LAKES OVERNIGHT THROUGH SATURDAY
MORNING. FROPA TIMING AMONG MODEL SOLUTIONS STILL IN GOOD
AGREEMENT...KICKING THE FRONT EASTWARD INTO LAKE HURON BY EARLY
FRIDAY EVENING. CONSENSUS AMONG MODEL QPF ALSO SUGGESTS MOST...IF
NOT ALL...SYNOPTIC PRECIP WILL END BY EARLY EVENING...SAVE FOR JUST
A SMALL SLIVER OF THE E/SE COUNTIES. HOWEVER...GIVEN THE STRONG S-N
ORIENTED UPPER JET CORE ALONG THE BASE OF THE INCOMING TROUGH THAT
SLIDES ACROSS THE CWA RIGHT BEHIND THE FRONT...AM STILL CONCERNED
THAT POST FRONTAL/JET FORCED RAINFALL LINGERS JUST A BIT LONGER INTO
THE EARLY TO MID EVENING HOURS THAN MODEL QPF SUGGESTS. WITH THAT IN
MIND...HAVE SLOWED PRECIP ENDING JUST A BIT LATE FRIDAY AFTERNOON
AND EARLY EVENING. PROBABLY THE PATH OF LEAST REGRET AT THIS POINT
GIVEN ALL THE FRIDAY EVENING ACTIVITIES. REGARDLESS...LOW LEVEL
COOL/MOIST AIR OVERSPREADING THE REGION FRIDAY EVENING (AND SOME
SEMBLANCE OF A WEAK LOW LEVEL TROUGH) MAY LEAD TO STRATUS AND
PERHAPS SOME PATCHY DRIZZLE FRIDAY EVENING. THEN...SUBSIDENCE AND
STRONG COLD ADVECTION CONTINUE THROUGH THE REST OF FRIDAY NIGHT AND
THROUGH THE DAY SATURDAY WITH H8 TEMPS DIPPING TO A FEW DEGREES
ABOVE 0C BY SATURDAY MORNING...AND DOWN AROUND 0C DURING THE DAY
SATURDAY. PLENTY ENOUGH COOL AIR/LAKE INSTABILITY AND SYNOPTIC
MOISTURE ALONG THE BACKSIDE OF THE DEPARTING LOW FOR LAKE
EFFECT/INDUCED RAIN SHOWERS OVERNIGHT FRIDAY NIGHT THROUGH A GOOD
PART OF SATURDAY. SO ANOTHER COOL-ISH SATURDAY LOOKS ON TAP WITH
MAINLY CLOUDY SKIES...SCATTERED RAIN SHOWERS AND SOME GUSTIER NW
WINDS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...IMPROVEMENT SATURDAY NIGHT AND
ESPECIALLY SUNDAY AS LARGE EXPANSE OF HIGH PRESSURE BUILDS OVER THE
REGION AND SUBSTANTIALLY DRIER AIR BUILDS OVERHEAD. COOLEST NIGHTS
OF FORECAST WILL OCCUR BOTH SATURDAY NIGHT AND SUNDAY NIGHT AS
CLEARING SKIES/WEAKENING WINDS SET THE STAGE FOR GOOD RADIATIONAL
COOLING. A GOOD DEAL OF SUNSHINE FOR SUNDAY WITH TEMPERATURES
REBOUNDING JUST A BIT TO THE MIDDLE 50S TO LOWER 60S.

MONDAY THROUGH THURSDAY...LARGE EXPANSE OF HIGH PRESSURE WILL REMAIN
THE DOMINANT WEATHER FEATURE ACROSS THE GREAT LAKES AND ACROSS
EASTERN CANADA THROUGH MUCH OF NEXT WEEK...WITH FAIR WEATHER
ANTICIPATED TO KICK OFF THE FIRST OFFICIAL WEEK OF FALL. GRADUAL
WARMING TREND THROUGH MIDWEEK AS TEMPERATURES REBOUND BACK TO AROUND
NORMAL READINGS FOR MID-LATE SEPTEMBER. GFS SOLUTION HAS ENOUGH
WARM/MOIST ADVECTION INTO THE UPPER MIDWEST/WESTERN GREAT LAKES TO
CONSIDER SOME CHANCES FOR SHOWERS BY THURSDAY. ECMWF IS NOWHERE
CLOSE WITH HIGH PRESSURE REMAINING DOMINANT. WILL FOLLOW THE DRY
ECMWF FOR NOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1146 PM EDT THU SEP 19 2013

VFR CONDITIONS WILL GRADUALLY DETERIORATE TO MVFR OVERNIGHT INTO
EARLY MORNING AS CHANCES OF SHOWERS AND THUNDERSTORMS INCREASE FROM
WEST TO EAST ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP THRU
MICHIGAN BY THIS EVENING. LLWS PERSIST OVERNIGHT AS LOW LEVEL WINDS
STRENGTHEN JUST AHEAD OF THE APPROACHING FRONT. SOUTHERLY SURFACE
WINDS AOB 10 KTS WILL SHIFT THE WEST BY AROUND MIDDAY TO EARLY
AFTERNOON WITH FROPA.

&&

.MARINE...
ISSUED AT 407 PM EDT THU SEP 19 2013

GUSTY SOUTH WINDS WILL CONTINUE TONIGHT...ESPECIALLY ACROSS
LAKE MICHIGAN...AS A STRONG COLD FRONT APPROACHES THE NORTHERN
LAKES. CURRENT TRENDS SUPPORT CONDITIONS REMAINING JUST BELOW SCA
CRITERIA. SHOWERS AND STORMS EXPECTED TO REDEVELOP THIS EVENING AND
OVERNIGHT...POSSIBLY LEADING TO LOCAL ENHANCEMENT OF WINDS. WINDS
VEER MORE WESTERLY BEHIND THE PASSING FRONT FRIDAY...REMAINING GUSTY
AT TIMES. WINDS INCREASE AND BECOME NORTHWEST FRIDAY NIGHT AND
SATURDAY. SCA/S WILL LIKELY BE NEEDED DURING THIS PERIOD.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

UPDATE...MR
SYNOPSIS...KB
SHORT TERM...MB
LONG TERM...BA
AVIATION...MR
MARINE...MB







AREA FORECAST DISCUSSION

NWS GAYLORD MI

 1047 PM EDT THU SEP 19 2013

.SYNOPSIS...
ISSUED AT 407 PM EDT THU SEP 19 2013

IT WILL BE WARM AND HUMID ACROSS NORTHERN MICHIGAN THROUGH
FRIDAY...AHEAD OF A STRONG COLD FRONT PUSHING ACROSS THE WESTERN
LAKES. THIS BOUNDARY WILL GENERATE SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS THROUGH FRIDAY...BEFORE SEASONAL CONDITIONS AND SOME
LAKE INDUCED RAINS RETURN TO NORTHERN MICHIGAN TO START THE WEEKEND.

HIGH PRESSURE WILL SETTLE INTO THE REGION SUNDAY AND MONDAY. THIS
PATTERN WILL GENERATE AN EXTENDED STRETCH OF DRY AND COMFORTABLE
WEATHER ACROSS THE GREAT LAKES FOR THE FIRST OFFICIAL WEEK OF FALL.

&&

.UPDATE...
ISSUED AT 1046 PM EDT THU SEP 19 2013

SEVERAL AREAS OF CONVECTION HAVE DEVELOPED OVER THE PAST FEW HOURS
ACROSS NRN LWR MICHIGAN...MAINLY SOUTH OF M-32...AS DEEPER
MOISTURE/850 MB THETA E RIDGING BEGINS TO SURGE INTO THE AREA ON
THE NOSE OF A STRENGTHENING LOW LEVEL JET. OVERALL INTENSITY OF
STORMS HAS BEEN RELATIVELY WEAK...AND ORGANIZATION HAS BEEN
LIMITED WELL AHEAD OF THE APPROACHING COLD FRONT. ADDITIONAL
CONVECTION CONTINUES TO DEVELOP ALONG AND AHEAD OF THE FRONT FROM
CENTRAL MISSOURI TO NW ILLINOIS TO SRN AND ERN WISCONSIN AND WRN
UPR MICHIGAN. THE FRONT ITSELF WILL STAY WEST OF OUR CWA
OVERNIGHT...AND EXPECT WAVES OF SHOWERS AND STORMS WILL CONTINUE
TO IMPACT OUR ENTIRE CWA THRU DAYBREAK. THUS...HAVE INCREASED POPS
FOR THE BALANCE OF THE NIGHT AND INTO EARLY FRIDAY MORNING AS THE
850 MB THETA E RIDGE LEANS INTO THE AREA AND THE LOW LEVEL JET
TAKES AIM DIRECTLY AT OUR CWA THRU THE NIGHT. LIKELY POPS WILL
EVENTUALLY BECOME CATEGORICAL LATE TONIGHT WITH THE ANTICIPATION
OF WIDESPREAD PRECIP SPREAD ACROSS MUCH OF OUR AREA THANKS TO A
POTENT SHORT WAVE RIDING NE AHEAD OF THE 500 MB TROUGH JUST AHEAD
OF THE FRONT.


UPDATE ISSUED AT 725 PM EDT THU SEP 19 2013

TWO RELATIVELY SMALL AREAS OF CONVECTION ARE APPROACHING PORTIONS
OF OUR CWA ATTM AHEAD OF THE APPROACHING COLD FRONT. THE SMALLEST
AND WEAKEST AREA OF CONVECTION IS MOVING NE THRU CENTRAL UPR
MICHIGAN...THE SRN EDGE OF WHICH MAY JUST GRAZE ERN UPR MICHIGAN.
THE SECOND...MORE ORGANIZED AREA IS LIFTING NE OUT OF S CENTRAL
WISCONSIN. TIME EXTRAPOLATION OF THIS LINE OF SHOWERS AND STORMS
BRINGS IT ONSHORE NEAR MBL BY AROUND 03Z...WHICH MATCHES FAIRLY
WELL WITH THE LATEST NAM AND WITH OUR GOING FORECAST. WILL LEAVE A
SMALL CHANCE OF PRECIP IN THE FORECAST IN THE MEANTIME...AND THEN
STEADILY INCREASE POPS FROM WEST TO EAST ACROSS OUR CWA AFTER 03Z.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 407 PM EDT THU SEP 19 2013

WARM...AND AN APPRECIABLY MUGGY AIRMASS...HAS OVERSPREAD THE NORTH
WOODS THIS AFTERNOON. DESPITE THIS...LOSS OF ANY DYNAMICS HAS LED
TO A DRY LATE MORNING AND EARLY AFTERNOON...WITH FOCUS FOR RAINS
SHIFTING WELL TO OUR SOUTH AND WEST. FORMER TIED TO REMNANT COLD
POOL AND LOW LEVEL JET DYNAMICS...WITH THE LATTER FOCUSED ALONG AND
AHEAD OF STRONG SHORTWAVE TROUGH AND ATTENDANT COLD FRONT SUPPORT.
THIS UPSTREAM SYSTEM WILL BE THE IMPETUS FOR ADDITIONAL SHOWERS AND
STORMS HEADING INTO TONIGHT AND FRIDAY. FORECAST CHALLENGES CENTER
ON THESE RAIN POSSIBILITIES.

TOUGH CALL FOR THE REMAINDER OF THIS AFTERNOON INTO EARLY THIS
EVENING. APPEARS FOCUS FOR ANY RAINS WILL BE CENTERED ON LOW LEVEL
CONVERGENCE AXES AND DEVELOPMENT OF SURFACE INSTABILITY. NOTED
CONVERGENCE AXIS DRIFTING SLOWLY NORTH ACROSS THE HIGHLANDS AS OF
THIS WRITING...WELL EVIDENT ON LOCAL RADAR IMAGERY. PER SPS SURFACE
ANALYSIS...BULLSEYE OF 1.5K TO 2.0K ML CAPE HAS DEVELOPED OVER
INTERIOR NORTHERN LOWER MICHIGAN. STILL EVIDENCE OF SOME WEAKISH
CINH TO OVERCOME. REALLY NOT SURE HOW THIS WILL ALL PLAY OUT...BUT
FEEL ABOVE DEFINITELY WORTHY OF KEEPING SOME SHOWER AND STORM
MENTION HEADING INTO EARLY THIS EVENING. FOR WHAT IT`S
WORTH...LATEST RAP SHOWS GOOD STORM DEVELOPMENT HEADING INTO THIS
PERIOD...FOCUSED ACROSS THE INTERIOR HIGHLANDS. RELATIVELY HIGH
PWATS SUPPORT LOCALLY HEAVY RAINS IF/WHERE CONVECTION DEVELOPS.

FOCUS WILL SHIFT TO LOW LEVEL JET DYNAMICS AND APPROACH OF COLD
FRONT FOR SHOWER AND STORM POTENTIAL HEADING INTO TONIGHT. RECENT
TRENDS AND PATTERN RECOGNITION SUPPORT BEST FORCED LOW LEVEL MASS
CONVERGENCE FOCUSED ALONG THE LAKE MICHIGAN CORRIDOR OF NORTHWEST
LOWER AND EASTERN UPPER MICHIGAN AFTER 05Z. MOISTURE REMAINS
GREAT...AND SIMPLE MAGNITUDE OF CONVERGENCE SHOULD BE ENOUGH TO
DRIVE ADDITIONAL ACTIVITY. WILL FOCUS BEST POTENTIAL IN THESE
AREAS...TAPERING TO JUST CHANCY WORDING ACROSS NORTHEAST LOWER
MICHIGAN. ELEVATED NATURE OF STORMS SHOULD PRECLUDE MUCH SEVERE
POTENTIAL. ONCE AGAIN... HOWEVER...GOOD MOISTURE PROFILES SUPPORT
LOCALLY HEAVY RAIN CONCERNS.

SURFACE FRONT LOOKS TO REMAIN AGGRESSIVE HEADING INTO FRIDAY...WITH
LATEST GFS/ECMWF TRENDS DRIVING THE FRONT INTO LAKE HURON THROUGH
EARLY AFTERNOON. PRE-FRONTAL SHOWERS AND STORMS SHOULD
CONTINUE...WITH STRONG UPPER JET SUPPORT AND FGEN DYNAMICS DRIVING
POST-FRONTAL RAINS IMMEDIATELY BEHIND THE SURFACE PORTION OF THE
FRONT. INHERITED GRIDS WELL TRENDED THIS DIRECTION WITH NO
SIGNIFICANT CHANGES NEEDED. DESPITE DECENT KINEMATICS...PLENTY OF
CLOUD COVER AND FASTER TIMING OF FRONT LOOKS TO KEEP SURFACE BASED
INSTABILITY IN CHECK...ONCE AGAIN PRECLUDING MUCH SEVERE WEATHER
POTENTIAL. LATEST SPC GRAPHICS CONCUR...KEEPING SLIGHT CHANCE
WORDING JUST TO OUR SOUTHEAST.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 407 PM EDT THU SEP 19 2013

OVERVIEW AND TRENDS: SUBSTANTIAL LONG WAVE TROUGHING IN PLACE THIS
MORNING FROM THE GULF OF ALASKA DOWN ALONG THE WEST COAST...WITH
DOWNSTREAM RIDGING/WARM AIR ACROSS THE CENTRAL CONUS INTO THE GREAT
LAKES...AND TROUGHING FROM GREENLAND DOWN THROUGH EASTERN CANADA.
LONG WAVE RIDGING IS STILL SLATED TO SLOWLY ADVANCE INTO THE EASTERN
CONUS THROUGH THE WEEKEND...WHILE LARGER SCALE FLOW FLATTENS AND
CONTRACTS TOWARD THE POLE AS WE GO THROUGH NEXT WEEK. SO...NO LONG
LASTING TRANSITION TOWARD COOL FALL WEATHER JUST YET.

ON THE SMALLER SCALE...A COUPLE OF STRONGER SHORT WAVES EMBEDDED
WITHIN THE LARGER SCALE FLOW...ONE PUSHING INTO THE NRN PLAINS THAT
WILL IMPACT US OVER THE NEXT FEW DAYS...AND ANOTHER STRONG WAVE JUST
OFF THE PACIFIC NW COAST THAT WILL PUSH INTO THE PAC NW LATER THIS
WEEKEND. CLOSER TO HOME...LOW PRESSURE STRETCHES FROM SOUTH-CENTRAL
CANADA INTO THE NRN PLAINS...AHEAD OF THE AFOREMENTIONED SHORT WAVE.
ASSOCIATED WARM FRONT STRETCHES DOWN THROUGH THE MIDWEST AND
TRAILING COLD FRONT FROM MINNESOTA INTO THE CENTRAL PLAINS. HAVE
DEALT WITH A COUPLE OF ROUNDS OF SHOWERS AND STORMS WORKING THROUGH
THE REGION ALONG ADVANCING LOW LEVEL MOISTURE AXIS PUSHING INTO THE
REGION NORTH OF THE WARM FRONT.

LATE FRIDAY AFTERNOON THROUGH SATURDAY...SHORT WAVE/THERMAL TROUGH
AXIS ADVANCES INTO THE GREAT LAKES OVERNIGHT THROUGH SATURDAY
MORNING. FROPA TIMING AMONG MODEL SOLUTIONS STILL IN GOOD
AGREEMENT...KICKING THE FRONT EASTWARD INTO LAKE HURON BY EARLY
FRIDAY EVENING. CONSENSUS AMONG MODEL QPF ALSO SUGGESTS MOST...IF
NOT ALL...SYNOPTIC PRECIP WILL END BY EARLY EVENING...SAVE FOR JUST
A SMALL SLIVER OF THE E/SE COUNTIES. HOWEVER...GIVEN THE STRONG S-N
ORIENTED UPPER JET CORE ALONG THE BASE OF THE INCOMING TROUGH THAT
SLIDES ACROSS THE CWA RIGHT BEHIND THE FRONT...AM STILL CONCERNED
THAT POST FRONTAL/JET FORCED RAINFALL LINGERS JUST A BIT LONGER INTO
THE EARLY TO MID EVENING HOURS THAN MODEL QPF SUGGESTS. WITH THAT IN
MIND...HAVE SLOWED PRECIP ENDING JUST A BIT LATE FRIDAY AFTERNOON
AND EARLY EVENING. PROBABLY THE PATH OF LEAST REGRET AT THIS POINT
GIVEN ALL THE FRIDAY EVENING ACTIVITIES. REGARDLESS...LOW LEVEL
COOL/MOIST AIR OVERSPREADING THE REGION FRIDAY EVENING (AND SOME
SEMBLANCE OF A WEAK LOW LEVEL TROUGH) MAY LEAD TO STRATUS AND
PERHAPS SOME PATCHY DRIZZLE FRIDAY EVENING. THEN...SUBSIDENCE AND
STRONG COLD ADVECTION CONTINUE THROUGH THE REST OF FRIDAY NIGHT AND
THROUGH THE DAY SATURDAY WITH H8 TEMPS DIPPING TO A FEW DEGREES
ABOVE 0C BY SATURDAY MORNING...AND DOWN AROUND 0C DURING THE DAY
SATURDAY. PLENTY ENOUGH COOL AIR/LAKE INSTABILITY AND SYNOPTIC
MOISTURE ALONG THE BACKSIDE OF THE DEPARTING LOW FOR LAKE
EFFECT/INDUCED RAIN SHOWERS OVERNIGHT FRIDAY NIGHT THROUGH A GOOD
PART OF SATURDAY. SO ANOTHER COOL-ISH SATURDAY LOOKS ON TAP WITH
MAINLY CLOUDY SKIES...SCATTERED RAIN SHOWERS AND SOME GUSTIER NW
WINDS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...IMPROVEMENT SATURDAY NIGHT AND
ESPECIALLY SUNDAY AS LARGE EXPANSE OF HIGH PRESSURE BUILDS OVER THE
REGION AND SUBSTANTIALLY DRIER AIR BUILDS OVERHEAD. COOLEST NIGHTS
OF FORECAST WILL OCCUR BOTH SATURDAY NIGHT AND SUNDAY NIGHT AS
CLEARING SKIES/WEAKENING WINDS SET THE STAGE FOR GOOD RADIATIONAL
COOLING. A GOOD DEAL OF SUNSHINE FOR SUNDAY WITH TEMPERATURES
REBOUNDING JUST A BIT TO THE MIDDLE 50S TO LOWER 60S.

MONDAY THROUGH THURSDAY...LARGE EXPANSE OF HIGH PRESSURE WILL REMAIN
THE DOMINANT WEATHER FEATURE ACROSS THE GREAT LAKES AND ACROSS
EASTERN CANADA THROUGH MUCH OF NEXT WEEK...WITH FAIR WEATHER
ANTICIPATED TO KICK OFF THE FIRST OFFICIAL WEEK OF FALL. GRADUAL
WARMING TREND THROUGH MIDWEEK AS TEMPERATURES REBOUND BACK TO AROUND
NORMAL READINGS FOR MID-LATE SEPTEMBER. GFS SOLUTION HAS ENOUGH
WARM/MOIST ADVECTION INTO THE UPPER MIDWEST/WESTERN GREAT LAKES TO
CONSIDER SOME CHANCES FOR SHOWERS BY THURSDAY. ECMWF IS NOWHERE
CLOSE WITH HIGH PRESSURE REMAINING DOMINANT. WILL FOLLOW THE DRY
ECMWF FOR NOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 725 PM EDT THU SEP 19 2013

VFR CONDITIONS WILL GRADUALLY DETERIORATE TO MVFR LATE TONIGHT AND
EARLY FRIDAY MORNING AS CHANCES OF SHOWERS AND THUNDERSTORMS
INCREASE FROM WEST TO EAST ALONG AND AHEAD OF A COLD FRONT THAT
WILL SWEEP THRU MICHIGAN BY FRIDAY EVENING. LLWS WILL DEVELOP
LATER THIS EVENING...ESPECIALLY ACROSS NW LWR MICHIGAN AS LOW
LEVEL WINDS STRENGTHEN JUST AHEAD OF THE APPROACHING FRONT.
SOUTHERLY SURFACE WINDS AOB 10 KTS WILL SHIFT THE WEST BY AROUND
MIDDAY TO EARLY AFTERNOON WITH FROPA.


&&

.MARINE...
ISSUED AT 407 PM EDT THU SEP 19 2013

GUSTY SOUTH WINDS WILL CONTINUE TONIGHT...ESPECIALLY ACROSS
LAKE MICHIGAN...AS A STRONG COLD FRONT APPROACHES THE NORTHERN
LAKES. CURRENT TRENDS SUPPORT CONDITIONS REMAINING JUST BELOW SCA
CRITERIA. SHOWERS AND STORMS EXPECTED TO REDEVELOP THIS EVENING AND
OVERNIGHT...POSSIBLY LEADING TO LOCAL ENHANCEMENT OF WINDS. WINDS
VEER MORE WESTERLY BEHIND THE PASSING FRONT FRIDAY...REMAINING GUSTY
AT TIMES. WINDS INCREASE AND BECOME NORTHWEST FRIDAY NIGHT AND
SATURDAY. SCA/S WILL LIKELY BE NEEDED DURING THIS PERIOD.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

UPDATE...MR
SYNOPSIS...KB
SHORT TERM...MB
LONG TERM...BA
AVIATION...MR
MARINE...MB







AREA FORECAST DISCUSSION

NWS GAYLORD MI

 726 PM EDT THU SEP 19 2013

.SYNOPSIS...
ISSUED AT 407 PM EDT THU SEP 19 2013

IT WILL BE WARM AND HUMID ACROSS NORTHERN MICHIGAN THROUGH
FRIDAY...AHEAD OF A STRONG COLD FRONT PUSHING ACROSS THE WESTERN
LAKES. THIS BOUNDARY WILL GENERATE SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS THROUGH FRIDAY...BEFORE SEASONAL CONDITIONS AND SOME
LAKE INDUCED RAINS RETURN TO NORTHERN MICHIGAN TO START THE WEEKEND.

HIGH PRESSURE WILL SETTLE INTO THE REGION SUNDAY AND MONDAY. THIS
PATTERN WILL GENERATE AN EXTENDED STRETCH OF DRY AND COMFORTABLE
WEATHER ACROSS THE GREAT LAKES FOR THE FIRST OFFICIAL WEEK OF FALL.

&&

.UPDATE...
ISSUED AT 725 PM EDT THU SEP 19 2013

TWO RELATIVELY SMALL AREAS OF CONVECTION ARE APPROACHING PORTIONS
OF OUR CWA ATTM AHEAD OF THE APPROACHING COLD FRONT. THE SMALLEST
AND WEAKEST AREA OF CONVECTION IS MOVING NE THRU CENTRAL UPR
MICHIGAN...THE SRN EDGE OF WHICH MAY JUST GRAZE ERN UPR MICHIGAN.
THE SECOND...MORE ORGANIZED AREA IS LIFTING NE OUT OF S CENTRAL
WISCONSIN. TIME EXTRAPOLATION OF THIS LINE OF SHOWERS AND STORMS
BRINGS IT ONSHORE NEAR MBL BY AROUND 03Z...WHICH MATCHES FAIRLY
WELL WITH THE LATEST NAM AND WITH OUR GOING FORECAST. WILL LEAVE A
SMALL CHANCE OF PRECIP IN THE FORECAST IN THE MEANTIME...AND THEN
STEADILY INCREASE POPS FROM WEST TO EAST ACROSS OUR CWA AFTER 03Z.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 407 PM EDT THU SEP 19 2013

WARM...AND AN APPRECIABLY MUGGY AIRMASS...HAS OVERSPREAD THE NORTH
WOODS THIS AFTERNOON. DESPITE THIS...LOSS OF ANY DYNAMICS HAS LED
TO A DRY LATE MORNING AND EARLY AFTERNOON...WITH FOCUS FOR RAINS
SHIFTING WELL TO OUR SOUTH AND WEST. FORMER TIED TO REMNANT COLD
POOL AND LOW LEVEL JET DYNAMICS...WITH THE LATTER FOCUSED ALONG AND
AHEAD OF STRONG SHORTWAVE TROUGH AND ATTENDANT COLD FRONT SUPPORT.
THIS UPSTREAM SYSTEM WILL BE THE IMPETUS FOR ADDITIONAL SHOWERS AND
STORMS HEADING INTO TONIGHT AND FRIDAY. FORECAST CHALLENGES CENTER
ON THESE RAIN POSSIBILITIES.

TOUGH CALL FOR THE REMAINDER OF THIS AFTERNOON INTO EARLY THIS
EVENING. APPEARS FOCUS FOR ANY RAINS WILL BE CENTERED ON LOW LEVEL
CONVERGENCE AXES AND DEVELOPMENT OF SURFACE INSTABILITY. NOTED
CONVERGENCE AXIS DRIFTING SLOWLY NORTH ACROSS THE HIGHLANDS AS OF
THIS WRITING...WELL EVIDENT ON LOCAL RADAR IMAGERY. PER SPS SURFACE
ANALYSIS...BULLSEYE OF 1.5K TO 2.0K ML CAPE HAS DEVELOPED OVER
INTERIOR NORTHERN LOWER MICHIGAN. STILL EVIDENCE OF SOME WEAKISH
CINH TO OVERCOME. REALLY NOT SURE HOW THIS WILL ALL PLAY OUT...BUT
FEEL ABOVE DEFINITELY WORTHY OF KEEPING SOME SHOWER AND STORM
MENTION HEADING INTO EARLY THIS EVENING. FOR WHAT IT`S
WORTH...LATEST RAP SHOWS GOOD STORM DEVELOPMENT HEADING INTO THIS
PERIOD...FOCUSED ACROSS THE INTERIOR HIGHLANDS. RELATIVELY HIGH
PWATS SUPPORT LOCALLY HEAVY RAINS IF/WHERE CONVECTION DEVELOPS.

FOCUS WILL SHIFT TO LOW LEVEL JET DYNAMICS AND APPROACH OF COLD
FRONT FOR SHOWER AND STORM POTENTIAL HEADING INTO TONIGHT. RECENT
TRENDS AND PATTERN RECOGNITION SUPPORT BEST FORCED LOW LEVEL MASS
CONVERGENCE FOCUSED ALONG THE LAKE MICHIGAN CORRIDOR OF NORTHWEST
LOWER AND EASTERN UPPER MICHIGAN AFTER 05Z. MOISTURE REMAINS
GREAT...AND SIMPLE MAGNITUDE OF CONVERGENCE SHOULD BE ENOUGH TO
DRIVE ADDITIONAL ACTIVITY. WILL FOCUS BEST POTENTIAL IN THESE
AREAS...TAPERING TO JUST CHANCY WORDING ACROSS NORTHEAST LOWER
MICHIGAN. ELEVATED NATURE OF STORMS SHOULD PRECLUDE MUCH SEVERE
POTENTIAL. ONCE AGAIN... HOWEVER...GOOD MOISTURE PROFILES SUPPORT
LOCALLY HEAVY RAIN CONCERNS.

SURFACE FRONT LOOKS TO REMAIN AGGRESSIVE HEADING INTO FRIDAY...WITH
LATEST GFS/ECMWF TRENDS DRIVING THE FRONT INTO LAKE HURON THROUGH
EARLY AFTERNOON. PRE-FRONTAL SHOWERS AND STORMS SHOULD
CONTINUE...WITH STRONG UPPER JET SUPPORT AND FGEN DYNAMICS DRIVING
POST-FRONTAL RAINS IMMEDIATELY BEHIND THE SURFACE PORTION OF THE
FRONT. INHERITED GRIDS WELL TRENDED THIS DIRECTION WITH NO
SIGNIFICANT CHANGES NEEDED. DESPITE DECENT KINEMATICS...PLENTY OF
CLOUD COVER AND FASTER TIMING OF FRONT LOOKS TO KEEP SURFACE BASED
INSTABILITY IN CHECK...ONCE AGAIN PRECLUDING MUCH SEVERE WEATHER
POTENTIAL. LATEST SPC GRAPHICS CONCUR...KEEPING SLIGHT CHANCE
WORDING JUST TO OUR SOUTHEAST.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 407 PM EDT THU SEP 19 2013

OVERVIEW AND TRENDS: SUBSTANTIAL LONG WAVE TROUGHING IN PLACE THIS
MORNING FROM THE GULF OF ALASKA DOWN ALONG THE WEST COAST...WITH
DOWNSTREAM RIDGING/WARM AIR ACROSS THE CENTRAL CONUS INTO THE GREAT
LAKES...AND TROUGHING FROM GREENLAND DOWN THROUGH EASTERN CANADA.
LONG WAVE RIDGING IS STILL SLATED TO SLOWLY ADVANCE INTO THE EASTERN
CONUS THROUGH THE WEEKEND...WHILE LARGER SCALE FLOW FLATTENS AND
CONTRACTS TOWARD THE POLE AS WE GO THROUGH NEXT WEEK. SO...NO LONG
LASTING TRANSITION TOWARD COOL FALL WEATHER JUST YET.

ON THE SMALLER SCALE...A COUPLE OF STRONGER SHORT WAVES EMBEDDED
WITHIN THE LARGER SCALE FLOW...ONE PUSHING INTO THE NRN PLAINS THAT
WILL IMPACT US OVER THE NEXT FEW DAYS...AND ANOTHER STRONG WAVE JUST
OFF THE PACIFIC NW COAST THAT WILL PUSH INTO THE PAC NW LATER THIS
WEEKEND. CLOSER TO HOME...LOW PRESSURE STRETCHES FROM SOUTH-CENTRAL
CANADA INTO THE NRN PLAINS...AHEAD OF THE AFOREMENTIONED SHORT WAVE.
ASSOCIATED WARM FRONT STRETCHES DOWN THROUGH THE MIDWEST AND
TRAILING COLD FRONT FROM MINNESOTA INTO THE CENTRAL PLAINS. HAVE
DEALT WITH A COUPLE OF ROUNDS OF SHOWERS AND STORMS WORKING THROUGH
THE REGION ALONG ADVANCING LOW LEVEL MOISTURE AXIS PUSHING INTO THE
REGION NORTH OF THE WARM FRONT.

LATE FRIDAY AFTERNOON THROUGH SATURDAY...SHORT WAVE/THERMAL TROUGH
AXIS ADVANCES INTO THE GREAT LAKES OVERNIGHT THROUGH SATURDAY
MORNING. FROPA TIMING AMONG MODEL SOLUTIONS STILL IN GOOD
AGREEMENT...KICKING THE FRONT EASTWARD INTO LAKE HURON BY EARLY
FRIDAY EVENING. CONSENSUS AMONG MODEL QPF ALSO SUGGESTS MOST...IF
NOT ALL...SYNOPTIC PRECIP WILL END BY EARLY EVENING...SAVE FOR JUST
A SMALL SLIVER OF THE E/SE COUNTIES. HOWEVER...GIVEN THE STRONG S-N
ORIENTED UPPER JET CORE ALONG THE BASE OF THE INCOMING TROUGH THAT
SLIDES ACROSS THE CWA RIGHT BEHIND THE FRONT...AM STILL CONCERNED
THAT POST FRONTAL/JET FORCED RAINFALL LINGERS JUST A BIT LONGER INTO
THE EARLY TO MID EVENING HOURS THAN MODEL QPF SUGGESTS. WITH THAT IN
MIND...HAVE SLOWED PRECIP ENDING JUST A BIT LATE FRIDAY AFTERNOON
AND EARLY EVENING. PROBABLY THE PATH OF LEAST REGRET AT THIS POINT
GIVEN ALL THE FRIDAY EVENING ACTIVITIES. REGARDLESS...LOW LEVEL
COOL/MOIST AIR OVERSPREADING THE REGION FRIDAY EVENING (AND SOME
SEMBLANCE OF A WEAK LOW LEVEL TROUGH) MAY LEAD TO STRATUS AND
PERHAPS SOME PATCHY DRIZZLE FRIDAY EVENING. THEN...SUBSIDENCE AND
STRONG COLD ADVECTION CONTINUE THROUGH THE REST OF FRIDAY NIGHT AND
THROUGH THE DAY SATURDAY WITH H8 TEMPS DIPPING TO A FEW DEGREES
ABOVE 0C BY SATURDAY MORNING...AND DOWN AROUND 0C DURING THE DAY
SATURDAY. PLENTY ENOUGH COOL AIR/LAKE INSTABILITY AND SYNOPTIC
MOISTURE ALONG THE BACKSIDE OF THE DEPARTING LOW FOR LAKE
EFFECT/INDUCED RAIN SHOWERS OVERNIGHT FRIDAY NIGHT THROUGH A GOOD
PART OF SATURDAY. SO ANOTHER COOL-ISH SATURDAY LOOKS ON TAP WITH
MAINLY CLOUDY SKIES...SCATTERED RAIN SHOWERS AND SOME GUSTIER NW
WINDS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...IMPROVEMENT SATURDAY NIGHT AND
ESPECIALLY SUNDAY AS LARGE EXPANSE OF HIGH PRESSURE BUILDS OVER THE
REGION AND SUBSTANTIALLY DRIER AIR BUILDS OVERHEAD. COOLEST NIGHTS
OF FORECAST WILL OCCUR BOTH SATURDAY NIGHT AND SUNDAY NIGHT AS
CLEARING SKIES/WEAKENING WINDS SET THE STAGE FOR GOOD RADIATIONAL
COOLING. A GOOD DEAL OF SUNSHINE FOR SUNDAY WITH TEMPERATURES
REBOUNDING JUST A BIT TO THE MIDDLE 50S TO LOWER 60S.

MONDAY THROUGH THURSDAY...LARGE EXPANSE OF HIGH PRESSURE WILL REMAIN
THE DOMINANT WEATHER FEATURE ACROSS THE GREAT LAKES AND ACROSS
EASTERN CANADA THROUGH MUCH OF NEXT WEEK...WITH FAIR WEATHER
ANTICIPATED TO KICK OFF THE FIRST OFFICIAL WEEK OF FALL. GRADUAL
WARMING TREND THROUGH MIDWEEK AS TEMPERATURES REBOUND BACK TO AROUND
NORMAL READINGS FOR MID-LATE SEPTEMBER. GFS SOLUTION HAS ENOUGH
WARM/MOIST ADVECTION INTO THE UPPER MIDWEST/WESTERN GREAT LAKES TO
CONSIDER SOME CHANCES FOR SHOWERS BY THURSDAY. ECMWF IS NOWHERE
CLOSE WITH HIGH PRESSURE REMAINING DOMINANT. WILL FOLLOW THE DRY
ECMWF FOR NOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 725 PM EDT THU SEP 19 2013

VFR CONDITIONS WILL GRADUALLY DETERIORATE TO MVFR LATE TONIGHT AND
EARLY FRIDAY MORNING AS CHANCES OF SHOWERS AND THUNDERSTORMS
INCREASE FROM WEST TO EAST ALONG AND AHEAD OF A COLD FRONT THAT
WILL SWEEP THRU MICHIGAN BY FRIDAY EVENING. LLWS WILL DEVELOP
LATER THIS EVENING...ESPECIALLY ACROSS NW LWR MICHIGAN AS LOW
LEVEL WINDS STRENGTHEN JUST AHEAD OF THE APPROACHING FRONT.
SOUTHERLY SURFACE WINDS AOB 10 KTS WILL SHIFT THE WEST BY AROUND
MIDDAY TO EARLY AFTERNOON WITH FROPA.

&&

.MARINE...
ISSUED AT 407 PM EDT THU SEP 19 2013

GUSTY SOUTH WINDS WILL CONTINUE TONIGHT...ESPECIALLY ACROSS
LAKE MICHIGAN...AS A STRONG COLD FRONT APPROACHES THE NORTHERN
LAKES. CURRENT TRENDS SUPPORT CONDITIONS REMAINING JUST BELOW SCA
CRITERIA. SHOWERS AND STORMS EXPECTED TO REDEVELOP THIS EVENING AND
OVERNIGHT...POSSIBLY LEADING TO LOCAL ENHANCEMENT OF WINDS. WINDS
VEER MORE WESTERLY BEHIND THE PASSING FRONT FRIDAY...REMAINING GUSTY
AT TIMES. WINDS INCREASE AND BECOME NORTHWEST FRIDAY NIGHT AND
SATURDAY. SCA/S WILL LIKELY BE NEEDED DURING THIS PERIOD.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

UPDATE...MR
SYNOPSIS...KB
SHORT TERM...MB
LONG TERM...BA
AVIATION...MR
MARINE...MB







AREA FORECAST DISCUSSION

NWS GRAND RAPIDS MI

 243 PM EDT WED SEP 18 2013

LATEST UPDATE...
LONG TERM

.SYNOPSIS...
ISSUED AT 148 PM EDT WED SEP 18 2013

A WARM FRONT WILL PUSH NORTHWARD THROUGH LOWER MICHIGAN TONIGHT
LEADING TO SOME SHOWERS AND THUNDERSTORMS. SOUTHWEST WINDS WILL
INCREASE THURSDAY ALLOWING FOR AND UNSEASONABLY WARM DAY. MOISTURE
FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA THURSDAY NIGHT
AND EARLY FRIDAY AHEAD OF A COLD FRONT. AS THIS FRONT PUSHES
THROUGH THE REGION FRIDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS
CAN BE EXPECTED.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 148 PM EDT WED SEP 18 2013

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND
STRENGTH OF THE CONVECTION. STORMS IN NW ILLINOIS ARE SHOWN TO
WEAKEN AS THEY HEAD TOWARD CHICAGO THIS AFTERNOON. HRRR SHOWS
CONVECTION REDEVELOPING OVER LAKE MI LATER TONIGHT AND MOVING INTO
THE HOLLAND TO MUSKEGON REGION. THIS MAKES SENSE WITH A
STRENGTHENING LOW LEVEL JET ACCOMPANYING THE WARM FRONT THAT
FEATURES ELEVATED INSTABILITY. NOT ALL MODELS HAVE THIS...BUT THE
HRRR TENDS TO HANDLE THE CONVECTION BETTER THAN MOST.  WILL
DECREASE POPS INLAND TONIGHT...BUT CLOSER TO LAKE MI WILL KEEP THE
LIKELY VALUES GOING. SEVERE WEATHER IS NOT FORECASTED...BUT
PERHAPS A HEAVY RAIN THREAT MAY EXIST.

A LULL IN THE CONVECTION IS EXPECTED THU AS NO FOCUSING MECHANISM
IS SHOWN. IT WILL BE A WARM AND INCREASINGLY HUMID. IT DOES BECOME
RATHER UNSTABLE...SO WILL HOLD ONTO A LOW POP FOR STORMS.

I RAISED POPS FOR FRIDAY. WITH PWAT VALUES APPROACHING 2 INCHES
AND A FRONT PRESSING IN ALONG WITH LIFT...IT SHOULD BE RATHER WET
AT TIMES. MODELS HAVE TRENDED SOMEWHAT FASTER WITH THE FRONT...SO
WE MAY BE ABLE TO START DRYING THINGS OUT FROM THE WEST BEFORE THE
END OF THE DAY. WILL WAIT TO SEE IF THIS TREND PERSIST BEFORE
CHANGING FRIDAYS FORECAST. I DID LOWER POPS FOR FRIDAY NIGHT
BECAUSE OF THIS. AS FOR SEVERE WEATHER...THE STRONGER DEEP LAYER
SHEAR IS SHOWN TO LAG BEHIND THE COLD FRONT...SO SOMEWHAT OF A
LIMITED RISK. STILL WITH BETTER INSTABILITY DEVELOPING AND
INCREASING WIND FIELDS ALONG WITH A LOW LEVEL JET MOVING IN AND
STRENGTHENING...A RISK STILL EXISTS. WILL NEED TO MONITOR TRENDS
CLOSELY IN THE COMING DAYS.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM EDT WED SEP 18 2013

AN UNEVENTFUL PERIOD IS EXCEPTED FOR THIS WEEKEND AND INTO THE
FIRST HALF OF NEXT WEEK. HIGH PRESSURE OVER THE UPPER MIDWEST ON
SATURDAY WILL SLOWLY MOVE OVER THE GREAT LAKES BY LATE IN THE
WEEKEND. THIS HIGH WILL BE STALLED OVER THE AREA AS A STORM SYSTEM
MOVES UP THE EAST COAST THROUGH THE FIRST HALF OF THE WORK WEEK.
SO FAIR WEATHER SHOULD PREVAIL.

LOWERED TEMPS A BIT FOR SATURDAY AND SUNDAY AS WE WILL BE UNDER A
THERMAL TROUGH . BOTH DAYS SHOULD SEE HIGHS STAYING IN THE 60S. WE
SHOULD SEE A WARM UP INTO THE WORK WEEK. HOWEVER LOW LEVEL FLOW
WILL BE FROM THE EAST OR SOUTHEAST...SO ANY MODERATION OF TEMPS
WILL BE GENTLE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 111 PM EDT WED SEP 18 2013

MAINLY VFR CONDITIONS ARE EXPECTED OVER THE NEXT 24 HOURS...
HOWEVER THERE COULD BE PATCHY AREAS OF FOG EARLY THU MORNING.

AS FOR THUNDERSTORM CHANCES...BELIEVE THEY WILL HOLD OFF UNTIL
AFTER 05Z THU...BUT COULD BE AROUND THROUGH 18Z THU. HOWEVER...
ALSO EXPECT THEY WILL REMAIN ISOLATED OR VERY WIDELY SCATTERED AND
SHOULD BE ABLE TO NAVIGATE AROUND THEM...AND ONLY BRIEFLY OVER
ANY ONE LOCATION. SEEMS AS THOU THE SOUTHERN TAF SITES...AZO...BTL
AND JXN...STAND A LONGER PERIOD OF POTENTIAL STORMS AS MOISTURE AND
LIFT ARE SLIGHTER MORE FAVORABLE THERE.

&&

.MARINE...
ISSUED AT 148 PM EDT WED SEP 18 2013

WINDS ARE FORECASTED TO BE STRONGER THU INTO THU NIGHT. MAY NEED
SMALL CRAFT AND BEACH HAZARDS TO COVER THIS. UNTIL THEN THE
SOUTHERLY FLOW WILL KEEP WAVES UP TO AROUND 2 TO 4
FEET...ESPECIALLY OFF OF LITTLE AND BIG SABLE POINTS.


&&

.HYDROLOGY...
ISSUED AT 148 PM EDT WED SEP 18 2013

LOCALIZED HEAVY RAIN WILL BE POSSIBLE WITH THE STORMS. TONIGHT AS
A LOW LEVEL JET MOVES IN PWAT VALUES CLIMB TO OVER 1.5 INCHES.
CORFIDI VECTORS SUGGESTS A LOCALIZED HEAVY RAIN THREAT MAY EXIST.
CURRENTLY IT APPEARS THAT AREAS ALONG THE LAKESHORE STAND THE
HIGHEST CHANCE FOR THE STORMS. A MORE WIDESPREAD ROUND OF STORMS
IS FORECASTED FOR THU NIGHT INTO FRI. PWAT VALUES LIKELY TO CLIMB
ABOVE 1.75 INCHES WITH ANOTHER LOW LEVEL JET PUSHING THROUGH.
CORFIDI VECTORS ALSO SUGGEST A HEAVY RAIN THREAT. HOW MUCH RAIN
FALLS WILL LIKELY DEPEND ON HOW EFFICIENT THE RAIN BECOMES AND HOW
THE CONVECTION EVOLVES. SUSPECT LOCALLY MORE THAN 2 INCHES WILL
FALL BY FRI NIGHT.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...JK
AVIATION...JK
HYDROLOGY...MJS
MARINE...MJS







AREA FORECAST DISCUSSION

NWS GRAND RAPIDS MI

 212 PM EDT WED SEP 18 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/HYDRO/MARINE

.SYNOPSIS...
ISSUED AT 148 PM EDT WED SEP 18 2013

A WARM FRONT WILL PUSH NORTHWARD THROUGH LOWER MICHIGAN TONIGHT
LEADING TO SOME SHOWERS AND THUNDERSTORMS. SOUTHWEST WINDS WILL
INCREASE THURSDAY ALLOWING FOR AND UNSEASONABLY WARM DAY. MOISTURE
FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA THURSDAY NIGHT
AND EARLY FRIDAY AHEAD OF A COLD FRONT. AS THIS FRONT PUSHES
THROUGH THE REGION FRIDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS
CAN BE EXPECTED.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 148 PM EDT WED SEP 18 2013

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND
STRENGTH OF THE CONVECTION. STORMS IN NW ILLINOIS ARE SHOWN TO
WEAKEN AS THEY HEAD TOWARD CHICAGO THIS AFTERNOON. HRRR SHOWS
CONVECTION REDEVELOPING OVER LAKE MI LATER TONIGHT AND MOVING INTO
THE HOLLAND TO MUSKEGON REGION. THIS MAKES SENSE WITH A
STRENGTHENING LOW LEVEL JET ACCOMPANYING THE WARM FRONT THAT
FEATURES ELEVATED INSTABILITY. NOT ALL MODELS HAVE THIS...BUT THE
HRRR TENDS TO HANDLE THE CONVECTION BETTER THAN MOST.  WILL
DECREASE POPS INLAND TONIGHT...BUT CLOSER TO LAKE MI WILL KEEP THE
LIKELY VALUES GOING. SEVERE WEATHER IS NOT FORECASTED...BUT
PERHAPS A HEAVY RAIN THREAT MAY EXIST.

A LULL IN THE CONVECTION IS EXPECTED THU AS NO FOCUSING MECHANISM
IS SHOWN. IT WILL BE A WARM AND INCREASINGLY HUMID. IT DOES BECOME
RATHER UNSTABLE...SO WILL HOLD ONTO A LOW POP FOR STORMS.

I RAISED POPS FOR FRIDAY. WITH PWAT VALUES APPROACHING 2 INCHES
AND A FRONT PRESSING IN ALONG WITH LIFT...IT SHOULD BE RATHER WET
AT TIMES. MODELS HAVE TRENDED SOMEWHAT FASTER WITH THE FRONT...SO
WE MAY BE ABLE TO START DRYING THINGS OUT FROM THE WEST BEFORE THE
END OF THE DAY. WILL WAIT TO SEE IF THIS TREND PERSIST BEFORE
CHANGING FRIDAYS FORECAST. I DID LOWER POPS FOR FRIDAY NIGHT
BECAUSE OF THIS. AS FOR SEVERE WEATHER...THE STRONGER DEEP LAYER
SHEAR IS SHOWN TO LAG BEHIND THE COLD FRONT...SO SOMEWHAT OF A
LIMITED RISK. STILL WITH BETTER INSTABILITY DEVELOPING AND
INCREASING WIND FIELDS ALONG WITH A LOW LEVEL JET MOVING IN AND
STRENGTHENING...A RISK STILL EXISTS. WILL NEED TO MONITOR TRENDS
CLOSELY IN THE COMING DAYS.



.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 341 AM EDT WED SEP 18 2013

THE ONLY PRECIPITATION FORECAST IN THE LONG TERM COMES IN THE FIRST
FORECAST PERIOD...FRIDAY NIGHT. A COLD FRONT SHOULD TRAVERSE
SOUTHWEST LOWER MICHIGAN FRIDAY EVENING/NIGHT. SUBTLE TIMING
DIFFERENCES IN THE MODELS IN TERMS OF FRONTAL PASSAGE...BUT
EXPECT THE FRONT WILL BISECT THE FORECAST AREA FRIDAY EVENING.
MAINTAINED SHOWERS AND STORMS AHEAD OF THE FRONT...OR IN ALL AREAS
EXCEPT THE FAR NORTHWEST TOWARD PENTWATER AND LUDINGTON. HAVE LIKELY
CHANCES (60/70 PCT) FOR SHOWERS/STORMS IN THE SOUTHEAST TOWARDS
LANSING AND JACKSON AS THE FRONT SHOULD BE PUSHING INTO AN UNSTABLE
AIRMASS. OVERALL...FEEL THE GFS HAS BEEN VERY CONSISTENT IN TIMING
OF THE FRONT AND USED IT FOR GUIDANCE TONIGHT.

AFTER FRIDAY NIGHT...THE SATURDAY THROUGH TUESDAY PERIOD LOOKS VERY
UNEVENTFUL. SURFACE HIGH PRESSURE WILL BE SITUATED ACROSS THE REGION
THROUGH THIS TIME FRAME WITH DRY AIR AND MAINLY CLEAR SKIES
EXPECTED. HIGH TEMPERATURES OVER THE WEEKEND WILL BE SEASONABLE IN
THE 60S TO AROUND 70 DEGREES. HIGHS EARLY NEXT WEEK SHOULD WARM INTO
THE LOWER 70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 111 PM EDT WED SEP 18 2013

MAINLY VFR CONDITIONS ARE EXPECTED OVER THE NEXT 24 HOURS...
HOWEVER THERE COULD BE PATCHY AREAS OF FOG EARLY THU MORNING.

AS FOR THUNDERSTORM CHANCES...BELIEVE THEY WILL HOLD OFF UNTIL
AFTER 05Z THU...BUT COULD BE AROUND THROUGH 18Z THU. HOWEVER...
ALSO EXPECT THEY WILL REMAIN ISOLATED OR VERY WIDELY SCATTERED AND
SHOULD BE ABLE TO NAVIGATE AROUND THEM...AND ONLY BRIEFLY OVER
ANY ONE LOCATION. SEEMS AS THOU THE SOUTHERN TAF SITES...AZO...BTL
AND JXN...STAND A LONGER PERIOD OF POTENTIAL STORMS AS MOISTURE AND
LIFT ARE SLIGHTER MORE FAVORABLE THERE.


&&

.MARINE...
ISSUED AT 148 PM EDT WED SEP 18 2013

WINDS ARE FORECASTED TO BE STRONGER THU INTO THU NIGHT. MAY NEED
SMALL CRAFT AND BEACH HAZARDS TO COVER THIS. UNTIL THEN THE
SOUTHERLY FLOW WILL KEEP WAVES UP TO AROUND 2 TO 4
FEET...ESPECIALLY OFF OF LITTLE AND BIG SABLE POINTS.

&&

.HYDROLOGY...
ISSUED AT 148 PM EDT WED SEP 18 2013

LOCALIZED HEAVY RAIN WILL BE POSSIBLE WITH THE STORMS. TONIGHT AS
A LOW LEVEL JET MOVES IN PWAT VALUES CLIMB TO OVER 1.5 INCHES.
CORFIDI VECTORS SUGGESTS A LOCALIZED HEAVY RAIN THREAT MAY EXIST.
CURRENTLY IT APPEARS THAT AREAS ALONG THE LAKESHORE STAND THE
HIGHEST CHANCE FOR THE STORMS. A MORE WIDESPREAD ROUND OF STORMS
IS FORECASTED FOR THU NIGHT INTO FRI. PWAT VALUES LIKELY TO CLIMB
ABOVE 1.75 INCHES WITH ANOTHER LOW LEVEL JET PUSHING THROUGH.
CORFIDI VECTORS ALSO SUGGEST A HEAVY RAIN THREAT. HOW MUCH RAIN
FALLS WILL LIKELY DEPEND ON HOW EFFICIENT THE RAIN BECOMES AND HOW
THE CONVECTION EVOLVES. SUSPECT LOCALLY MORE THAN 2 INCHES WILL
FALL BY FRI NIGHT.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...DUKE
AVIATION...JK
HYDROLOGY...MJS
MARINE...MJS







AREA FORECAST DISCUSSION

NWS MARQUETTE MI

 124 AM EDT WED SEP 18 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 421 PM EDT TUE SEP 17 2013

17Z WV IMAGERY AND RUC ANALYSIS INDICATED A WELL-DEFINED SHORTWAVE
LIFTING NE THROUGH ERN IA. DPVA...7H FGEN AND 305K ISENTROPIC ASCENT
ASSOC WITH THE SHORTWAVE HAS SUPPORTED AN AREA OF SHOWERS OVER
NORTHEAST IA. VIS SATELLITE HAS SHOWN AN EXPANSION OF DIURNAL CU
FROM MNM-DELTA-ALGER COUNTIES EASTWARD IN AN AREA OF HIGHER
DEWPOINTS (UPPER 40 TO LOWER 50S) AIDED BY SOUTHERLY FLOW OFF LAKE
MI AND BAY OF GREEN BAY. RDGG ALOFT AND AT THE SFC HAS KEPT THE REST
OF THE FCST AREA GENERALLY CLOUD FREE THIS AFTERNOON.

TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE
NORTHEAST...MOISTURE WILL INCREASE AND BRING SOME LIGHT WAA PCPN
INTO THE AREA AS 300K-310K ISENTROPIC ASCENT SPREADS FROM SE MN AND
WRN WI TOWARD UPPER MI. THE NAM/GFS ARE STILL A BIT MORE AGGRESSIVE
IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF.
GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE NAM/GFS MAY BE TOO QUICK
SO USED MORE OF A MODEL BLEND FOR POPS WITH ONLY A 30 PCT CHC OF
LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER WITH SLIGHT CHC ACROSS
MUCH OF THE REST OF THE WEST HALF.

WEDNESDAY...GIVEN PREDICTED TRACK OF ERN IA SHORTWAVE EXPECT BEST
FORCING FOR SHRA TO BE MAINLY CENTRAL COUNTIES IN THE MORNING AND
THEN TO SPREAD INTO THE EASTERN COUNTIES IN THE AFTERNOON. HAVE ONLY
SLIGHT CHC POPS FOR SHRA WEST AWAY FROM BETTER FORCING ASSOC WITH
SHORTWAVE. MODEL MLCAPES OTHER THAN NAM SHOW ONLY MARGINAL
INSTABILITY OF A FEW HUNDRED J/KG AT BEST OVER THE AREA SO WILL ONLY
INCLUDED SLIGHT CHC MENTION OF TS IN THE GRIDS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 421 PM EDT TUE SEP 17 2013

LITTLE CHANGES TO THE LARGE SCALE PATTERN FOR THE LONG TERM PERIOD
OVER THE LAST 24 HOURS. AREA WILL BE UNDER WEAK UPPER RIDGING TO
START THE PERIOD...WHICH WILL LEAD TO BROAD WARM AIR ADVECTION AND
THE POTENTIAL FOR SOME SHOWERS/THUNDERSTORMS WEDNESDAY NIGHT INTO
THURSDAY AS A WARM FRONT LIFTS ACROSS THE AREA. BEST CHANCES ON
WEDNESDAY NIGHT WILL BE EARLY ON WHEN THE STRONGEST WARM AIR
ADVECTION MOVES THROUGH AND BEFORE THE DEEPER MOISTURE STARTS TO
CUTOUT. THIS BROAD WAA WILL ALSO LEAD TO TEMPERATURES RISING TO
ABOVE NORMAL VALUES FOR WEDNESDAY NIGHT AND THURSDAY...WITH LOWS IN
THE UPPER 50S AND LOWER 60S AND HIGHS IN THE 70S TO LOWER 80S.
FINALLY FOR WEDNESDAY NIGHT...SINCE THE MODELS CONTINUE TO SHOW THE
POTENTIAL FOR LOW CLOUDS AND FOG...DID UP THE FOG TO AREAS FOR SOME
LOCATIONS IN FAVORED UPSLOPE HIGHER TERRAIN.

PRECIPITATION CHANCES WILL INCREASE HEADING INTO LATE THURSDAY
AFTERNOON AND THURSDAY NIGHT...AS THE UPPER TROUGH PUSHES NORTHEAST
THROUGH THE UPPER GREAT LAKES AND ONTARIO. AN ASSOCIATED LOW
PRESSURE SYSTEM WILL MOVE THROUGH NORTHWEST ONTARIO...BUT IT WILL
PUSH A COLD FRONT EAST ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY
MORNING. ECMWF IS STILL SHOWING THE SLOWEST FRONTAL PASSAGE...WITH
THE PRECIPITATION LINGERING INTO EARLY FRIDAY AFTERNOON AS ANOTHER
WAVE RIDES UP THE FRONT. THERE CONTINUES TO BE SOME MINOR TIMING
DIFFERENCES IN THE COLD FRONT PASSAGE AND SHOWERS...BUT THE GENERAL
IDEA IS SIMILAR WITH MOST LOCATIONS LIKELY TO SEE 0.25-0.5IN OF
RAIN. AS FOR THUNDER...THERE ARE DECENT VARIATIONS IN THE
INSTABILITY...WITH SOME MODELS EVEN SHOWING UP TO 3000 J/KG OF ML
CAPE IF THERE IS ENOUGH CLEARING/HEATING IN THE AFTERNOON. 0-6KM AND
EFFECTIVE SHEAR VALUES STILL LOOK TO BE ON THE MARGINAL SIDE
(25-30KTS) ON THURSDAY AFTERNOON AND THEN INCREASE RIGHT ALONG THE
FRONTAL BOUNDARY. WOULD THINK THE BEST OPPORTUNITY FOR STRONGER
THUNDERSTORMS WOULD BE RIGHT ALONG THE FRONT AS IT MOVES INTO THE
WESTERN CWA LATE THURSDAY AFTERNOON INTO THE EVENING. AT THIS
POINT...THINK BRIEF HEAVY RAIN AND MARGINALLY SEVERE HAIL WOULD BE
THE BIGGEST THREATS IF THE UPDRAFTS CAN BE SUSTAINED.

DRIER AND COOLER AIR WILL MOVE IN RIGHT BEHIND THE FRONT AND SHOULD
LEAD TO A PERIOD OF DRY WEATHER AND EVEN SOME CLEARING FOR A FEW
HOURS. BUT MUCH COLDER AIR...WILL START TO SURGE IN WITH MORE
LOW LEVEL MOISTURE LATER FRIDAY AFTERNOON AND CONTINUE INTO THE
FIRST PART OF SATURDAY. WITH THE FLOW BEING MORE
WEST-NORTHWEST...EXPECT THE MOST CLOUDS TO BE OVER THE NORTH HALF
OF THE CWA AND WITH THE COLDER AIR THERE...EVEN SOME LAKE ENHANCED
CLOUDS (DELTA-T VALUES BETWEEN 10-14) IN THOSE WIND FAVORED AREAS.
WITH THE LATEST TRENDS OF CLOUD DEPTHS BEING 3-4KFT...SHOULD BE
ENOUGH FOR ISOLATED/SCATTERED SHOWERS AND MAY NEED TO ADJUST POPS A
LITTLE HIGHER OVER THE COMING SHIFTS.

THE UPPER TROUGH WILL LIFT NORTHEAST ON SATURDAY NIGHT AND ALLOW
UPPER RIDGING AND HIGH PRESSURE TO BUILD INTO THE AREA FOR SUNDAY.
THUS...EXPECT A DRY SECOND HALF OF THE WEEKEND...ALTHOUGH
TEMPERATURES WON/T WARM UP TOO SIGNIFICANTLY (WITH HIGHS AROUND 60).
ALSO...SATURDAY NIGHT COULD SEE SOME FROST OVER THE INTERIOR WEST
WHERE SKIES BEGIN TO CLEAR AND WINDS LET UP DUE TO THE APPROACHING
HIGH.

THIS HIGH WILL QUICKLY SHIFT EAST-NORTHEAST INTO QUEBEC ON
MONDAY...AS THE AREA IS UNDER THE UPPER RIDGE AXIS. STILL EXPECT
MONDAY TO BE DRY AND MUCH WARMER (HIGHS IN THE MID-UPPER 60S)...BUT
THE NEXT UPPER TROUGH IS LURKING TO THE WEST. THIS UPPER TROUGH
LOOKS TO GIVE A GLANCING BLOW TO THE CWA ON MONDAY NIGHT INTO
TUESDAY AND WILL HIGHLIGHT THE BEST POPS OVER THE NORTHWESTERN HALF
OF THE CWA.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 124 AM EDT WED SEP 18 2013

EXPECT LLWS AT ALL 3 TAF SITES INTO THIS MRNG WITH NOCTURNAL COOLING
CAUSING A RADIATION INVERSION AND DECOUPLING OF A LIGHTER SFC FLOW
FM THE STRONGER SSW WINDS ABOVE THE INVERSION. THIS INCRSGLY MOIST
SSW WIND WL BRING MVFR/IFR CIGS INTO UPR MI BY SUNRISE. BEST CHC FOR
THE IFR CONDITIONS WL BE AT IWD THIS MRNG DOWNWIND OF THE LOWER CIGS
OBSVD UPSTREAM. ALTHOUGH THERE MAY BE SOME DIURNAL RECOVERY IN CIG
HGT THIS AFTN...PERSISTENCE OF LLVL MSTR UNDER LO INVRN THRU THIS
EVNG IN ADVANCE OF APRCHG WARM FNT WARRANTS A MENTION OF CONTINUED
MVFR CIGS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 421 PM EDT TUE SEP 17 2013

BETWEEN HIGH TO THE EAST AND LOW PRES OVER THE PLAINS...SRLY WINDS
WILL REMAIN UP TO 20 KNOTS INTO WED. WINDS SHOULD THEN REMAIN BELOW
20 KNOTS UNTIL LATE THU NIGHT AND FRI WHEN A COLD FRONT MOVES
THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO
SAT. WINDS WILL DECREASE BLO 20 KT BY SUNDAY AS HIGH PRESSURE BUILDS
IN FM THE WEST.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KC
MARINE...VOSS







AREA FORECAST DISCUSSION

NWS TWIN CITIES/CHANHASSEN MN

 1047 PM CDT THU SEP 19 2013

.UPDATE...
FOR 06Z AVIATION DISCUSSION BELOW

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 237 PM CDT THU SEP 19 2013

AS OF 2 PM...THE FRONT WAS STILL SLOWLY MOVING ACROSS THE EASTERN
HALF OF MINNESOTA...BUT IT HAD NOT PASSED THROUGH THE TWIN CITIES
METRO. EVEN WITH THE THE THUNDERSTORM ACTIVITY DIMINISHING IN
WESTERN WI...THERE IS STILL A NICE POOL OF INSTABILITY IN WI AND
EASTERN IA. THE STEEPEST CAPE GRADIENT EXTENDS FROM ROUGHLY EAU
CLAIRE...TO ALBERT LEA. THIS SAME AREA HAS SEEN MOSTLY CLEAR SKIES
SO FAR TODAY...BUT TOWERING CU HAS FILLED IN ACROSS MUCH OF THIS
AREA WITH SCATTERED SHOWERS. IF THERE IS TO BE CONVECTIVE REDEVELOP
IN THE MPX FORECAST AREA...THEN THIS IS THE SPOT TO KEEP AN EYE ON.
THERE IS A NICE SHORTWAVE IN EASTERN NE THAT SHOULD CONTINUE TO
DRIVE STORMS ACROSS IA. FARTHER NORTH THERE ARE FAR MORE QUESTIONS
AND WE THINK ACTIVITY WILL LARGELY REMAIN EAST AND SOUTH OF HERE.
THAT BEING SAID...THE 19.17Z HRRR HAS ANOTHER LINE OF STORMS GOING
RIGHT ALONG THE AFOREMENTIONED CAPE GRADIENT LATE THIS
AFTERNOON...AROUND 21Z FOR EAU CLAIRE.

OTHERWISE...LOOK FOR SOME NICE COLD ADVECTION TONIGHT AND TOMORROW
WITH A DRIER AND BREEZY NORTHWEST FLOW. THERE IS ACTUALLY A
SECONDARY COLD FRONT BACK ACROSS THE DAKOTAS ASSOCIATED WITH THAT
STRATO CU DECK AND TEMPS IN THE UPPER 40S AND LOWER 50S. THAT IS ON
TAP FOR TOMORROW. THE AIR WILL MODIFY...BUT WOULD NOT BE SURPRISED
IF SOME SITES IN CENTRAL MN STRUGGLE TO GET OUT OF THE 50S. WE
LOWERED HIGHS TOMORROW A BIT...BUT PROBABLY COULD HAVE GONE A COUPLE
DEGREES MORE. IT WILL BE A VERY FALL LIKE DAY TOMORROW.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 355 PM CDT THU SEP 19 2013

LOTS OF DISCREPANCIES EXIST IN THE LONG RANGE WITH RESPECT TO
TIMING OF INDIVIDUAL WAVES...BUT MODELS DO AGREE ON THE GENERAL
PROGRESSION OF THE LARGE SCALE UPPER AIR PATTERN. THE WEEKEND WILL
START WITH A RIDGE MOVING ACROSS THE NATIONS MID SECTION...BUT BY
MONDAY...AN ANOMALOUSLY STRONG UPPER RIDGE WILL BECOME CENTERED
OVER THE THE SE CONUS...WITH A DEEP TROUGH CARVING OUT ACROSS WRN
NOAM. DURING THE WEEK...THIS WRN TROUGH WILL SLOWLY DRIFT TOWARD
THE CENTRAL CONUS...APPROACHING THE UPPER MS VALLEY TOWARD THE END
OF NEXT WEEK.

SATURDAY STILL LOOKS TO START OUT IN THE UPPER 30S TO MID
40S...BUT DID NUDGE LOWS A COUPLE OF DEGREES UP...AS THE RIDGE
AXIS DOES NOT LOOK TO COME INTO WRN MN UNTIL CLOSER TO DAY
BREAK...KEEPING WINDS UP ENOUGH TO KEEP THE ATMO FROM COMPLETELY
DECOUPLING. OTHERWISE...ONLY THING REMOTELY SIGNIFICANT ABOUT THE
WEATHER THIS WEEKEND WILL BE THE BREEZY CONDITIONS DEVELOPING
SUNDAY AS GRADIENT TIGHTENS SIGNIFICANTLY ACROSS MN IN RESPONSE TO
A 1020 MB HIGH OVER THE GREAT LAKES AND A 995 MB LOW OVER THE WRN
DAKOTAS. 1000-850 WINDS OFF THE NAM INCREASE TO OVER 30 KTS BY THE
AFTERNOON IN WRN MN...SO SHOULD TURN INTO A FAIRLY BREEZY DAY IN
OUR TYPICALLY WINDY AREAS.

TIMING DETAILS QUICKLY SHOW UP WITH THE WAVE DUE TO MOVE THROUGH ON
MONDAY AS MODELS STRUGGLE TO PIN DOWN HOW THE RIDGING OVER THE
SOUTHEAST WILL IMPACT THE SPEED OF WAVES BACK THIS DIRECTION. THE
GEM/GFS CONTINUE TO BRING A POTENT NEGATIVELY TILTED THROUGH
ACROSS THE NRN PLAINS MONDAY...WITH A BAND OF SHRA/TSRA COMING
ALONG WITH AS WELL. THE 19.12 ECMWF SLOWED DOWN CONSIDERABLY WITH
THIS FEATURE...BRINGING IT THROUGH ABOUT 12 HRS LATER...WITH
PRECIP COMING THROUGH MONDAY NIGHT AS A RESULT. GIVEN TIMING
DIFFERENCES...CONTINUED WITH CHANCES POPS MON/MON NIGHT...BUT AT
SOME POINT...GIVEN THE DYNAMICS ASSOCIATED WITH THE NEGATIVELY
TITLED WAVE...WE SHOULD BE HEADING FOR A HIGH POP/LOW QPF TYPE
SCENARIO ONCE BETTER TIMING CAN BE NAILED DOWN. GIVEN THE RIDGING
TO THE SE...ITS USUALLY A SAFER BET TO GO THE SLOWER ROUTE.

THIS RIDGE TO THE SOUTHEAST WILL BE A MAJOR PLAYER FOR THE WEATHER
HERE THROUGH THE REST OF THE WEEK...AS IT WILL ACT TO DEFLECT
MUCH OF THE SHORTWAVE ENERGY TO THE NW OF THE MPX AREA. HAVE SEEN
MODELS RESPOND TO THIS...WITH EACH RUN GRADUALLY SLOWING DOWN WHEN
THE NEXT SYSTEM WILL IMPACT THE AREA. THE GFS WANTS TO BRING A
POTENT FRONT/LOW THROUGH WED NIGHT/THU...WHILE THE ECMWF HOLDS OFF
UNTIL FRIDAY. MUCH LIKE WAS STATED IN THE PREVIOUS
PARAGRAPH...GIVEN THE STRENGTH OF THE RIDGING TO THE SE...THE
SLOWER PROGRESSION WILL LIKELY BE THE WAY THINGS GO...BUT GIVEN
THE BLENDING PROCEDURE USED...PRECIP CHANCES RETURN WEDNESDAY.

THOUGH THERE IS UNCERTAINTY ABOUT PRECIP...WHAT IS MORE CERTAIN IS
THAT SW FLOW RESULTING FROM THE TROUGH WEST/RIDGE EAST WILL BRING
WITH IT TEMPERATURES WELL ABOVE NORMAL...WITH HIGHS IN THE 80S
LOOKING POSSIBLE BY THE MIDDLE OF NEXT WEEK...WHICH THANKS TO OUR
RAPIDLY FALLING AVERAGE HIGHS WOULD BE CLOSE 20 DEGREES ABOVE
NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1047 PM CDT THU SEP 19 2013

STILL EXPECTING THE STRATUS DECK OVER ERN ND TO EXPAND SOUTHEAST
OVERNIGHT ACROSS THE TAF SITES...AND CAUSE CIGS TO GRADUALLY LOWER
TO MVFR /POSSIBLY EVEN IFR AT TIMES/ BETWEEN 06Z AND 12Z FRIDAY.
CONTINUE TO FAVOR THE RAP AND HRRR MODELS...WHICH BRING LOW CIGS
INTO NORTHERN-MOST SITES /KAXN AND KSTC/ BETWEEN 06Z AND
08Z...THEN EAST AND SOUTH TO THE REACH THE REMAINDER OF THE SITES
BY DAYBREAK. THEN EXPECT CIGS TO STAY BKN-OVC IN THE MVFR LEVEL
THROUGH MUCH OF THE MORNING...SHOWING IMPROVEMENT DURING THE
AFTERNOON. THE DIRECTIONAL COMPONENT OF THE WIND WILL GENERALLY
VARY FROM 280-310 DEGREES THROUGH THE PERIOD. SPEEDS AOB 10KTS
THROUGH THE NIGHT...BECOMING GUSTY /UPPER TEENS TO LOWER 20S IN
KNOTS/ AGAIN AFTER 14Z FRIDAY. WIDELY SCATTERED LIGHT RAIN SHOWERS
/VFR VSBYS/ WILL ALSO BE POSSIBLE ON FRIDAY AS THE TROUGH ROTATES
OVER...ALTHOUGH COVERAGE/PROBABILITY IS TOO LOW TO WARRANT
INCLUSION IN THE TAFS AT THIS TIME.

KMSP...

STRATUS CLOUDS WITH MVFR CIGS ARE EXPECTED AROUND 10Z...AND
POSSIBLY BELOW 1700 FT FOR A WINDOW OF TIME BETWEEN 12Z AND 18Z.
SCATTERING OUT IS THEN EXPECTED GRADUALLY THROUGHOUT THE AFTERNOON.
WINDS 280-310 DIRECTIONALLY AOA 9KTS THROUGH THE PERIOD...GUSTING
TO BETWEEN 20 AND 24 KTS AFTER 15Z FRIDAY.

/OUTLOOK FOR KMSP/
SAT...VFR. NORTHWEST WIND 5 KTS.
SUN...VFR. SOUTHEAST WIND 12-15 KTS.
MON...VFR. SOUTHEAST WIND 10-15 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...CLF
LONG TERM...MPG
AVIATION...LS







AREA FORECAST DISCUSSION

NWS TWIN CITIES/CHANHASSEN MN

 651 PM CDT THU SEP 19 2013

.UPDATE...
FOR 00Z AVIATION DISCUSSION BELOW

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 237 PM CDT THU SEP 19 2013

AS OF 2 PM...THE FRONT WAS STILL SLOWLY MOVING ACROSS THE EASTERN
HALF OF MINNESOTA...BUT IT HAD NOT PASSED THROUGH THE TWIN CITIES
METRO. EVEN WITH THE THE THUNDERSTORM ACTIVITY DIMINISHING IN
WESTERN WI...THERE IS STILL A NICE POOL OF INSTABILITY IN WI AND
EASTERN IA. THE STEEPEST CAPE GRADIENT EXTENDS FROM ROUGHLY EAU
CLAIRE...TO ALBERT LEA. THIS SAME AREA HAS SEEN MOSTLY CLEAR SKIES
SO FAR TODAY...BUT TOWERING CU HAS FILLED IN ACROSS MUCH OF THIS
AREA WITH SCATTERED SHOWERS. IF THERE IS TO BE CONVECTIVE REDEVELOP
IN THE MPX FORECAST AREA...THEN THIS IS THE SPOT TO KEEP AN EYE ON.
THERE IS A NICE SHORTWAVE IN EASTERN NE THAT SHOULD CONTINUE TO
DRIVE STORMS ACROSS IA. FARTHER NORTH THERE ARE FAR MORE QUESTIONS
AND WE THINK ACTIVITY WILL LARGELY REMAIN EAST AND SOUTH OF HERE.
THAT BEING SAID...THE 19.17Z HRRR HAS ANOTHER LINE OF STORMS GOING
RIGHT ALONG THE AFOREMENTIONED CAPE GRADIENT LATE THIS
AFTERNOON...AROUND 21Z FOR EAU CLAIRE.

OTHERWISE...LOOK FOR SOME NICE COLD ADVECTION TONIGHT AND TOMORROW
WITH A DRIER AND BREEZY NORTHWEST FLOW. THERE IS ACTUALLY A
SECONDARY COLD FRONT BACK ACROSS THE DAKOTAS ASSOCIATED WITH THAT
STRATO CU DECK AND TEMPS IN THE UPPER 40S AND LOWER 50S. THAT IS ON
TAP FOR TOMORROW. THE AIR WILL MODIFY...BUT WOULD NOT BE SURPRISED
IF SOME SITES IN CENTRAL MN STRUGGLE TO GET OUT OF THE 50S. WE
LOWERED HIGHS TOMORROW A BIT...BUT PROBABLY COULD HAVE GONE A COUPLE
DEGREES MORE. IT WILL BE A VERY FALL LIKE DAY TOMORROW.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 355 PM CDT THU SEP 19 2013

LOTS OF DISCREPANCIES EXIST IN THE LONG RANGE WITH RESPECT TO
TIMING OF INDIVIDUAL WAVES...BUT MODELS DO AGREE ON THE GENERAL
PROGRESSION OF THE LARGE SCALE UPPER AIR PATTERN. THE WEEKEND WILL
START WITH A RIDGE MOVING ACROSS THE NATIONS MID SECTION...BUT BY
MONDAY...AN ANOMALOUSLY STRONG UPPER RIDGE WILL BECOME CENTERED
OVER THE THE SE CONUS...WITH A DEEP TROUGH CARVING OUT ACROSS WRN
NOAM. DURING THE WEEK...THIS WRN TROUGH WILL SLOWLY DRIFT TOWARD
THE CENTRAL CONUS...APPROACHING THE UPPER MS VALLEY TOWARD THE END
OF NEXT WEEK.

SATURDAY STILL LOOKS TO START OUT IN THE UPPER 30S TO MID
40S...BUT DID NUDGE LOWS A COUPLE OF DEGREES UP...AS THE RIDGE
AXIS DOES NOT LOOK TO COME INTO WRN MN UNTIL CLOSER TO DAY
BREAK...KEEPING WINDS UP ENOUGH TO KEEP THE ATMO FROM COMPLETELY
DECOUPLING. OTHERWISE...ONLY THING REMOTELY SIGNIFICANT ABOUT THE
WEATHER THIS WEEKEND WILL BE THE BREEZY CONDITIONS DEVELOPING
SUNDAY AS GRADIENT TIGHTENS SIGNIFICANTLY ACROSS MN IN RESPONSE TO
A 1020 MB HIGH OVER THE GREAT LAKES AND A 995 MB LOW OVER THE WRN
DAKOTAS. 1000-850 WINDS OFF THE NAM INCREASE TO OVER 30 KTS BY THE
AFTERNOON IN WRN MN...SO SHOULD TURN INTO A FAIRLY BREEZY DAY IN
OUR TYPICALLY WINDY AREAS.

TIMING DETAILS QUICKLY SHOW UP WITH THE WAVE DUE TO MOVE THROUGH ON
MONDAY AS MODELS STRUGGLE TO PIN DOWN HOW THE RIDGING OVER THE
SOUTHEAST WILL IMPACT THE SPEED OF WAVES BACK THIS DIRECTION. THE
GEM/GFS CONTINUE TO BRING A POTENT NEGATIVELY TILTED THROUGH
ACROSS THE NRN PLAINS MONDAY...WITH A BAND OF SHRA/TSRA COMING
ALONG WITH AS WELL. THE 19.12 ECMWF SLOWED DOWN CONSIDERABLY WITH
THIS FEATURE...BRINGING IT THROUGH ABOUT 12 HRS LATER...WITH
PRECIP COMING THROUGH MONDAY NIGHT AS A RESULT. GIVEN TIMING
DIFFERENCES...CONTINUED WITH CHANCES POPS MON/MON NIGHT...BUT AT
SOME POINT...GIVEN THE DYNAMICS ASSOCIATED WITH THE NEGATIVELY
TITLED WAVE...WE SHOULD BE HEADING FOR A HIGH POP/LOW QPF TYPE
SCENARIO ONCE BETTER TIMING CAN BE NAILED DOWN. GIVEN THE RIDGING
TO THE SE...ITS USUALLY A SAFER BET TO GO THE SLOWER ROUTE.

THIS RIDGE TO THE SOUTHEAST WILL BE A MAJOR PLAYER FOR THE WEATHER
HERE THROUGH THE REST OF THE WEEK...AS IT WILL ACT TO DEFLECT
MUCH OF THE SHORTWAVE ENERGY TO THE NW OF THE MPX AREA. HAVE SEEN
MODELS RESPOND TO THIS...WITH EACH RUN GRADUALLY SLOWING DOWN WHEN
THE NEXT SYSTEM WILL IMPACT THE AREA. THE GFS WANTS TO BRING A
POTENT FRONT/LOW THROUGH WED NIGHT/THU...WHILE THE ECMWF HOLDS OFF
UNTIL FRIDAY. MUCH LIKE WAS STATED IN THE PREVIOUS
PARAGRAPH...GIVEN THE STRENGTH OF THE RIDGING TO THE SE...THE
SLOWER PROGRESSION WILL LIKELY BE THE WAY THINGS GO...BUT GIVEN
THE BLENDING PROCEDURE USED...PRECIP CHANCES RETURN WEDNESDAY.

THOUGH THERE IS UNCERTAINTY ABOUT PRECIP...WHAT IS MORE CERTAIN IS
THAT SW FLOW RESULTING FROM THE TROUGH WEST/RIDGE EAST WILL BRING
WITH IT TEMPERATURES WELL ABOVE NORMAL...WITH HIGHS IN THE 80S
LOOKING POSSIBLE BY THE MIDDLE OF NEXT WEEK...WHICH THANKS TO OUR
RAPIDLY FALLING AVERAGE HIGHS WOULD BE CLOSE 20 DEGREES ABOVE
NORMAL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 650 PM CDT THU SEP 19 2013

PRIMARY CONCERN THIS TAF ISSUANCE IS THE POTENTIAL FOR WIDESPREAD
STRATUS /MVFR TO IFR CIGS/ TO DEVELOP OVERNIGHT AND PERSIST
THROUGH FRIDAY MORNING. COLD CYCLONIC FLOW AND ANOTHER SURGE OF
MOISTURE ROTATE OVER THE AREA TONIGHT INTO FRIDAY AS THE MID LEVEL
TROUGH PASSES. THE HRRR AND RAP CONTINUE TO SHOW THE PRIME TIME
FOR THE AFOREMENTIONED LOW CIGS WILL BE AS EARLY AS 06-08Z AT
NORTHERN-MOST SITES /KAXN AND KSTC/...SPREADING EAST AND SOUTH TO
THE REACH THE REMAINDER OF THE SITES AROUND/AFTER DAYBREAK. THEN
EXPECT CIGS TO STAY OF THE BKN-OVC VARIETY THROUGH THE
MORNING...SHOWING GRADUAL IMPROVEMENT DURING THE AFTERNOON. THE
DIRECTIONAL COMPONENT OF THE WIND WILL GENERALLY VARY FROM 280-310
DEGREES THROUGH THE PERIOD. SPEEDS AOB 10KTS THROUGH THE
NIGHT...BECOMING GUSTY /UPPER TEENS TO LOWER 20S IN KNOTS/ AGAIN AFTER
14Z FRIDAY. A FEW LIGHT RAIN SHOWERS WILL ALSO BE POSSIBLE ON FRIDAY AS
THE TROUGH ROTATES OVER...ALTHOUGH COVERAGE/PROBABILITY IS TOO LOW
TO WARRANT INCLUSION IN THE TAFS AT THIS TIME. ATTENDANT VSBYS
WOULD BE VFR ANYWAY.

KMSP...
FEW-SCT MVFR LEVEL CLOUDS JUST SOUTHWEST OF KMSP WILL ERODE AT
THE BEGINNING OF THE PERIOD...MOST LIKELY PRIOR TO AFFECTING THE
SITE. VFR CONDITIONS ARE THEN EXPECTED UNTIL CLOSER TO DAYBREAK
FRIDAY AS STRATUS CLOUDS FILTER IN FROM THE NORTHWEST. EXPECT CIGS
TO DEGRADE TO MVFR BY 11Z...AND POSSIBLY BELOW 1700 FT FOR A
WINDOW OF TIME BETWEEN 12Z AND 16Z. SHOULD SEE SOME BREAKS AND
IMPROVEMENT TO AROUND 2KFT BY 16Z...WITH SCATTERING NOT UNTIL
CLOSER TO 00Z SATURDAY. WINDS 280-310 DIRECTIONALLY AOA 9KTS THROUGH
THE PERIOD...GUSTING TO BETWEEN 20 AND 24 KTS AFTER 15Z FRIDAY.

/OUTLOOK FOR KMSP/

SAT...VFR. NORTHWEST WIND 5 KTS.
SUN...VFR. SOUTHEAST WIND 12-15 KTS.
MON...VFR. SOUTHEAST WIND 10-15 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...CLF
LONG TERM...MPG
AVIATION...LS







AREA FORECAST DISCUSSION

NWS DULUTH MN

 307 PM CDT WED SEP 18 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED SEP 18 2013

AT 300PM/2000Z...THERE WAS A POORLY DEFINED LOW PRESSURE SYSTEM IN
THE WESTERN DAKOTAS. A COLD FRONT STRETCHED FROM THE LOW INTO
WYOMING. A WARM FRONT STRETCHED FROM SE NORTH DAKOTA TO ILLINOIS.
MUCH OF THE NORTHLAND AND UPPER MIDWEST HAD CLOUDY TO MOSTLY
CLOUDY SKIES AHEAD OF THE LIFTING WARM FRONT...WHILE MUCH OF THE
NORTHERN AND CENTRAL PLAINS HAD SUNNY SKIES SOUTH AND WEST OF THE
WARM FRONT. TEMPERATURES ACROSS THE NORTHLAND RANGED FROM THE
UPPER 50S TO MID 60S...BUT AREAS JUST SOUTH AND WEST OF THE
APPROACHING HAD TEMPERATURES IN THE 80S. THERE WERE REPORTS OF FOG
AND DRIZZLE ALONG THE NORTH SHORE...WHILE OTHER PARTS OF THE
NORTHLAND HAD SOME REDUCED VISIBILITY FROM MIST.

TONIGHT...THE WARM FRONT WILL BEGIN TO LIFT INTO THE NORTHLAND
THIS EVENING...SO THERE MAY BE SOME INITIAL PARTIAL CLEARING IN
THE WESTERN AND SOUTHERN FORECAST AREA. HOWEVER...THE EASTERLY
FLOW OFF OF LAKE SUPERIOR WILL CONTINUE TO CAUSE PLENTY OF CLOUD
COVER FOR THE ARROWHEAD AND TWIN PORTS AREAS WITH DRIZZLE AND FOG.
THERE WILL BE AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS
FROM THE WEST OVERNIGHT AS INSTABILITY AND MOISTURE TRANSPORT
INCREASES ACROSS THE NORTHLAND AND THE LOW PRESSURE SYSTEM AND
COLD FRONT MOVE INTO WESTERN MINNESOTA. THE MODELS ARE IN POOR
AGREEMENT...SO CONFIDENCE IS LOW. I DID NOT RAISE PCPN CHANCES
INTO THE LIKELY CATEGORY DUE TO THE UNCERTAINTY. IF STORMS DO
DEVELOP...THERE COULD BE A STRAY STRONG STORM ACROSS THE WESTERN
FORECAST AREA WITH SMALL HAIL AND GUSTY WINDS. THE EVENING SHIFT
WILL NEED TO LOOK INTO THE THREAT OF FOG FOR OTHER PARTS OF THE
FORECAST AREA. SOME MODELS ARE BEGINNING TO SUGGEST FOG...BUT FOR
NOW...I AM ASSUMING MORE WIDESPREAD REDUCED VISIBILITY FROM MIST.

THURSDAY...THE MODELS ARE IN A BIT BETTER AGREEMENT FOR
TOMORROW...BUT MY CONFIDENCE ON THE FORECAST IS STILL NOT AS MUCH
AS I WOULD LIKE TO HAVE AT LESS THAN 24 HOURS FROM THE FORECAST.
I GAVE INCREASING PCPN CHANCES TO THE CENTRAL AND EASTERN FORECAST
AREA DURING THE LATE MORNING AND AFTERNOON AS THE LOW PRESSURE
SYSTEM AND COLD FRONT MOVE THROUGH THE NORTHLAND. MOST OF THE
MODELS SHOW QUITE A BIT OF PCPN ACROSS THE EASTERN HALF OF THE
FORECAST AREA. THERE IS A MINOR THREAT OF STRONG TO SEVERE
STORMS...MAINLY ACROSS THE SOUTH CENTRAL AND SE FORECAST AREA
WHICH MAY NEAR THE WARM FRONT. IT LOOKS LIKE THERE COULD BE PLENTY
OF CAPE...MAYBE A COUPLE THOUSAND J/KG OR SO...BUT THAT THE BETTER
SHEAR WILL LAG WELL BEHIND THE CAPE. THEREFORE...THERE MAY BE A
LACK OF ORGANIZATION TO ANY STORMS THAT DO DEVELOP. I WOULD NOT BE
SURPRISED IF THERE ARE A FEW BRIEF STORMS WITH LARGE HAIL...GUSTY
WINDS...AND SHORT DOWNPOURS. HIGH TEMPERATURES ACROSS THE
NORTHLAND SHOULD BE IN THE MID TO UPPER 70S.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED SEP 18 2013

SHOWERS AND STORMS SHOULD BE ONGOING THURSDAY EVENING AS THE FRONT
CONTINUES TO MOVE EAST THROUGH FAR EASTERN MINNESOTA AND
WISCONSIN/UPPER MICHIGAN. SOME OF THE STORMS COULD BE QUITE STRONG
OR SEVERE GIVEN STRENGTH OF THE FRONT AND INSTABILITY.
HOWEVER...SHEAR IS LACKING AND IS LARGELY BEHIND THE BOUNDARY AND
THAT COULD BE A LIMITING FACTOR. STRONG CAA WILL OCCUR BEHIND THE
FRONT AND THE UPPER TROUGH WILL MOVE OVER MINNESOTA BY 12Z FRIDAY.
COLD AIR ALOFT SHOULD LEAD TO A CHANCE FOR ADDITIONAL SHOWERS AND
CLOUDS LATE THURSDAY NIGHT INTO FRIDAY...MAINLY OVER NORTHERN
AREAS. 850MB TEMPS ARE FORECAST TO DROP TO 1-5C OVER THE CWA ON
FRIDAY. GUSTY WINDS WILL ALSO OCCUR BEHIND THE FRONT WITH THE CAA
AND PRESSURE RISES.

AN UPPER RIDGE WILL APPROACH THE CWA SATURDAY...MOVING OVER THE
CWA SUNDAY. A DRY PERIOD WILL OCCUR SATURDAY INTO SUNDAY. ANOTHER
SHORTWAVE WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS EARLY
NEXT WEEK. AT THIS TIME...THIS FEATURE DOES NOT LOOK VERY STRONG.

HIGHS FRIDAY WILL ONLY RANGE FROM THE MIDDLE FIFTIES TO MIDDLE
SIXTIES BUT WILL WARM EACH DAY THROUGH WEDNESDAY WHICH SHOULD
FEATURE HIGHS IN THE UPPER SIXTIES TO MIDDLE SEVENTIES. A COUPLE
COLD NIGHTS ARE IN STORE FRIDAY NIGHT AND SATURDAY NIGHT...WITH
SATURDAY NIGHT LOOKING THE COLDEST. FROST OR A FREEZE WILL BE
POSSIBLE BOTH NIGHTS...ALTHOUGH THERE MAY BE TOO MUCH WIND FRIDAY
NIGHT. THE GRADIENT STARTS TO STRENGTHEN SATURDAY NIGHT...BUT WE
MAY BE ABLE TO DECOUPLE EARLY ENOUGH WITH CLEAR SKIES TO GET A
FREEZE/FROST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1243 PM CDT WED SEP 18 2013

IFR OR LOW MVFR CEILINGS/VSBYS COVERED THE NORTHLAND EARLY THIS
AFTERNOON WITH SOME DRIZZLE. CEILINGS/VSBYS WILL SLOWLY INCREASE
THROUGH THE AFTERNOON...BUT STILL REMAIN IFR/MVFR FOR MOST
AREAS. AREAS AROUND LAKE SUPERIOR WILL SEE THE LOWEST
CEILINGS/VSBYS AND THE BEST CHANCE FOR DRIZZLE. VISIBLE SATELLITE
IMAGERY SHOWED CLEARING OCCURRING ACROSS FAR SOUTHWEST MINNESOTA
AND THE RAP CONDENSATION PRESSURE DEFICITS WERE DOING A DECENT JOB
WITH THESE LOW CLOUDS. IT SUGGESTS THIS CLEARING WILL CONTINUE
NORTHEAST THIS AFTERNOON...AFFECTING KBRD LATE THIS
AFTERNOON/EARLY EVENING. CONFIDENCE IN THE CLEARING MAKING IT TOO
MUCH FURTHER NORTH AND EAST IS LOW...AND WE KEPT THE LOWER CLOUDS
IN THE REST OF THE TAFS...AND LOWERED VSBYS LATER THIS EVENING.
THE MOIST AIRMASS WILL REMAIN IN PLACE THROUGH THE PERIOD.

A COLD FRONT WILL INTO THE RED RIVER VALLEY LATE TONIGHT. SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE ALONG AND AHEAD OF THE FRONT
AND WE HIGHLIGHTED THE BEST CHANCE FOR THAT IN THE TAFS. SOME OF
THE STORMS COULD BE QUITE STRONG LATE TONIGHT INTO THURSDAY.
ADJUSTMENTS TO THE TIMING WILL LIKELY BE NEEDED LATER TONIGHT.
SOME OF THE CAMS SUGGEST THERE WILL BE A LINE THAT MOVES
THROUGH...WHICH WOULD BE A RELATIVELY SHORT DURATION EVENT...WHILE
THE DETERMINISTIC MODELS SUGGEST THE PRECIP WILL BE GREATER IN
COVERAGE AND LAST LONGER.

&&

.MARINE...
ISSUED AT 1243 PM CDT WED SEP 18 2013

WE UPDATED THE WINDS OVER LAKE SUPERIOR AND INCREASED THEM A BIT
MORE FROM ABOUT SILVER BAY TO THE TWIN PORTS TO PORT WING.
PRESSURE FALLS TO THE SOUTHWEST AND A TIGHTENING GRADIENT SHOULD
ALLOW WINDS TO PICK UP AND BE SUSTAINED AROUND 15 KNOTS LATER THIS
AFTERNOON INTO THE EVENING. WE KEPT WAVES FROM 2 TO 4 FEET...BUT
SMALL CRAFT ADVISORY THRESHOLDS MAY BE REACHED BRIEFLY LATE
TONIGHT INTO EARLY EVENING. WE`LL MONITOR WINDS/WAVES FROM THE
BUOYS/LAND OBS AND ADJUST AS NEEDED.

.PRELIMINARY POINT TEMPS/POPS...
DLH  60  73  52  60 /  50  70  50  20
INL  61  74  49  55 /  50  60  30  30
BRD  66  76  51  62 /  50  60  10  10
HYR  66  80  52  63 /  50  70  50  10
ASX  62  79  54  62 /  40  70  60  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&

$$

SHORT TERM...GROCHOCINSKI
LONG TERM...MELDE
AVIATION...MELDE
MARINE...MELDE







AREA FORECAST DISCUSSION

NWS TWIN CITIES/CHANHASSEN MN

 127 PM CDT WED SEP 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT WED SEP 18 2013

AN AREA OF LOW PRESSURE WAS LOCATED OVER THE WESTERN DAKOTAS...WITH
HIGH PRESSURE ACROSS THE EASTERN SEABOARD. THIS SETUP RESULTED IN
SOUTHERLY FLOW ACROSS THE UPPER MIDWEST WAS BRINGING WARM MOIST AIR
TO THE REGION. THIS WAA WAS EASILY IDENTIFIED BY LOOKING AT THE H850
TEMPERATURE ADVECTION OFF THE SPC MESOANALYSIS PAGE. THE LOW LEVEL
MOISTURE WAS EVIDENT BY THE STRATUS DECK THAT COVERED THE ENTIRE
UPPER MISSISSIPPI RIVER VALLEY WITH POCKETS OF DRIZZLE AND FOG. A
FEW AREAS OF ELEVATED CONVECTION MANAGED TO DEVELOP ALONG THE
EAST/WEST MUCAPE GRADIENT. SINCE THESE STORMS WERE ELEVATED...THEY
WERE UNABLE TO TAKE ADVANTAGE OF THE 0-1KM SHEAR AND HELICITY OF
30KTS AND 300M2/S2 RESPECTIVELY...AND DRIFTED HARMLESSLY EAST
NORTHEAST WITH THE MEAN WIND.

MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING HOW THE STATUS FIELD
WILL EVOLVE TODAY. H850 TEMPS WILL INCREASE FROM AROUND 12-15C EARLY
THIS MORNING...TO 20-22C THIS AFTERNOON. THAT WARM LAYER ALOFT WILL
ONLY ENHANCE THE CAPPING INVERSION AND LIMIT MIXING THIS AFTERNOON.
AS A RESULT IT MAY BE DIFFICULT TO LOOSE THE CLOUDS...WHICH IN TURN
WILL HAMPER TODAYS HIGH TEMPERATURES. MOST LIKELY IT WILL EITHER BE
BOOM OR BUST WITH HIGHS TODAY. THE NAM AND HRRR CLEAR OUT THE
CLOUDS BY EARLY THIS AFTERNOON WHICH WOULD FAVOR A WARMER SOLUTION.
HOWEVER...JUST WITHIN THE INDIVIDUAL MEMBERS OF THE SREF THE HIGH
TEMPERATURE TODAY VARIES FROM 89 TO 77 AT KMSP. MEMBER 2 OF THE
HOPWRF KEEPS THE CLOUDS ACROSS THE CWA THROUGH 21Z THIS
AFTERNOON...SO HAVE TRENDED BACK TEMPERATURES SLIGHTLY TO REFLECT
THE MORE CLOUDY SCENARIO. AS THE WARM FRONT LIFT NORTHWARD THIS
AFTERNOON AND OVERNIGHT PRECIP CHANCES WILL DECREASE FROM SOUTH TO
NORTH...BUT RETURN AGAIN EARLY THURSDAY MORNING AS THE COLD FRONT
APPROACHES FROM THE WEST.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 328 AM CDT WED SEP 18 2013

SHOWERS AND SOME THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE
FAR EASTERN DAKOTAS AND WESTERN MINNESOTA THURSDAY MORNING. MOIST
SOUTHERLY FLOW WITH PW VALUES OF 1.5 TO 1.8 INCHES...ROUGHLY 220
PERCENT OF NORMAL...AND 850 MB TEMPS OF +20C WILL OVERSPREAD THE
REGION. THE CAPPING INVERSION PRODUCED BY THIS ABUNDANCE OF WARM
AIR ALOFT WILL LIKELY CONTRIBUTE TO CONSIDERABLE CLOUDINESS
THROUGH MUCH OF THE DAY WITH LITTLE HOPE OF DEEP MIXING AND
ERODING THE CAP SUFFICIENTLY AHEAD OF THE FRONT. THIS WILL PROVE
DETRIMENTAL ON WIDESPREAD CONVECTIVE CHANCES TO SOME
DEGREE...UNLESS SURFACE TEMPS DO WARM INTO THE 80S. BEST POTENTIAL
FOR THIS WOULD BE ACROSS WESTERN WI AS FROPA WILL TAKE PLACE LATE
IN THE DAY. MID LEVEL LAPSE RATES WILL CONTRIBUTE TO AROUND 2000
J/KG MLCAPE...SO IF THE CAP DOES ERODE...WIDESPREAD THUNDERSTORMS
CAN BE EXPECTED. MODEST SPEED SHEAR WOULD ALSO HELP ORGANIZE A FEW
STORMS ENOUGH FOR A MARGINAL SEVERE THREAT.

COOLER AND DRIER AIR WILL FOLLOW THURSDAY NIGHT INTO SATURDAY. AS
THE HIGH PUSHES OVERHEAD FRIDAY NIGHT...TEMPERATURES COULD FALL
INTO THE 30S IN SOME LOCATIONS IF WINDS DECOUPLE.

RETURN FLOW WILL COMMENCE SATURDAY NIGHT AND STRENGTHEN INTO EARLY
NEXT WEEK AS TROUGHING DIGS INTO THE PACIFIC NORTHWEST. SOUTHWEST
FLOW WILL KEEP THE STORM TRACK WEST OF THE REGION...AND COLD
FRONTS/DISTURBANCES PUSHING THROUGH WILL NOT HAVE MUCH PUNCH. ONE
SUCH FRONT IS PROGGED FOR MONDAY AND MONDAY NIGHT...WITH THE ECMWF
THE STRONGEST OF ALL GUIDANCE. ONLY LOW POPS WERE JUSTIFIED.
TEMPERATURES WILL BE ABOVE AVERAGE EARLY NEXT WEEK...AND 80S MAY
RETURN FOR MIDWEEK WITH 925 MB TEMPS CLIMBING INTO THE 20S C.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 125 PM CDT WED SEP 18 2013

AN ACTIVE PATTERN OVER THE NEXT 24 HOURS AS A WARM FRONT PASSES
ACROSS THE AREA THIS EVENING...FOLLOWED BY ITS ASSOCIATED COLD
FRONT DURG THE DAY TMRW. LOW LEVEL SE WINDS BECOME MORE SLY TNGT
BEHIND THE WMFNT...INVITING MORE LOW LEVEL MOISTURE AND WARM AIR
INTO THE AREA. THIS WILL AGAIN TRANSLATE TO CONDITIONS DROPPING TO
IFR...AND POSSIBLY LIFR OVERNIGHT THRU DAYBREAK TMRW. THE TIMING
OF THE DEGRADATION MAY EVEN OCCUR LATE THIS EVE AS HAPPENED YDA SO
CONDITIONS WILL CERTAINLY NEED TO BE MONITORED. AS THE CDFNT APCHS
TMRW MRNG...SHWRS WILL SPREAD S TO N AHEAD OF THE FNT INTO THE
REGION. THERE ARE SOME CONFLICTING SIGNALS AS TO THE POTENTIAL FOR
THUNDER...BUT TRYING TO PINPOINT IT TO A TERMINAL IS HIGHLY
PROBLEMATIC AND CONFIDENCE IS LOW SO HAVE OPTED TO OMIT ITS
MENTION ATTM BUT PARAMETERS ARE THERE FOR TSTM DEVELOPMENT. THE
COLD FROPA IS SHOWN WITH THE WIND SHIFT TO W-NW DURG THE DAY
TMRW...AND THIS WILL ALSO MAKE FOR IMPROVEMENT IN CONDITIONS. HOW
QUICK IS THE MAIN QUESTION. HAVE OPTED TO GO WITH A SLOWER
IMPROVEMENT AS IT WILL TAKE SOME TIME FOR DRIER AIR TO MOVE INTO
THE REGION EVEN WITH THE FROPA...SO CEILINGS UNDER 2000 FT ARE A
VIABLE POSSIBILITY FOR MOST IF NOT ALL TAF SITES THRU MIDDAY THU.

KMSP...STARTED OUT WITH 1200 FT CEILINGS BUT THERE IS A REASONABLE
CHC OF SEEING CIGS RISE TO VFR LEVELS LATE THIS AFTN. THIS IS
BEFORE CONDITIONS AGAIN BECOME SIGNIFICANTLY DEGRADED OVERNIGHT
THRU THE FIRST HALF OF THE DAY TMRW. WILL LOOK FOR CEILINGS TO
AGAIN DROP BELOW 1700 FT ARND MIDNIGHT...AND MAY WELL BE EARLIER
THAN THAT RATHER THAN LATER. CONDS THEN CONTINUE TO DETERIORATE
THRU THE OVERNIGHT HRS INTO DAYBREAK...ALONG WITH -RA MOVING INTO
THE AREA. NO INCLUSION OF TS ATTM BUT THAT MAY CHANGE WITH LATER
TAF ISSUANCES. -RA REMAINS OVER THE AREA THRU MIDDAY TMRW THEN
CONDS WILL SLOWLY IMPROVE TMRW AFTN.

/OUTLOOK FOR KMSP/
FRI...VFR. WINDS NW 15G25KT.
SAT...VFR. WINDS NW 5-10KT.
SUN...VFR. WINDS SE 15G20KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JPC








AREA FORECAST DISCUSSION

NWS DULUTH MN

 1244 PM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 1038 AM CDT WED SEP 18 2013

AT 1030AM/1530Z...THE NORTHLAND HAD CLOUDY SKIES AS A RESULT OF THE
SOUTHERLY SATURATED LOW LEVEL FLOW. THE NORTHLAND WAS COOL BUT
HUMID WITH CURRENT TEMPERATURES IN THE MID 50S TO LOW 60S WITH
GENERALLY LOW DEW POINT DEPRESSIONS. THERE WAS AN AREA OF
LINGERING SHOWERS AND STORMS NEAR AND SOUTH OF THE HAYWARD AND
PHILLIPS AREA...AND THIS WAS DUE TO LINGERING OVERNIGHT CONVECTION
IN THE AXIS OF HIGHER 850 HPA MOISTURE TRANSPORT. PARTS OF THE
NORTH SHORE HAD FOG...MAINLY DUE TO THE EASTERLY FLOW OFF THE
LAKE. THERE WERE REPORTS OF LIGHT RAIN AND DRIZZLE ACROSS THE
FORECAST AREA.

FORECASTING PCPN CHANCES AND WEATHER TYPE WILL BE DIFFICULT TODAY.
THE MODELS ARE IN SOMEWHAT POOR AGREEMENT UNTIL MORE SIGNIFICANT
PCPN LIKELY MOVES INTO THE WESTERN FORECAST AREA LATER TODAY WITH
THE APPROACHING COLD FRONT. I UPDATED THE FORECAST THROUGH THIS
AFTERNOON...FOCUSING ON THE LATEST TRENDS. I PROLONGED CLOUD COVER
TODAY...BUT HAVE SOME CLEARING HAPPENING FROM THE SW THIS
AFTERNOON AS A WARM FRONT BEGINS TO LIFT TOWARDS THE NORTHLAND. I
ADDED PATCHY DRIZZLE ACROSS THE NORTHLAND THROUGH 1 PM SINCE IT
SEEMS THIS REALLY LOW CLOUD COVER IS PRODUCING REPORTS OF LIGHT
RAIN OR DRIZZLE HERE AND THERE. I AM ASSUMING THERE WILL BE A
LITTLE LIFTING OF THE CEILINGS THIS AFTERNOON...BUT IF NOT
MUCH...I MIGHT NEED TO PROLONG THE PATCHY DRIZZLE. EXCEPT FOR THE
SE FORECAST...I KEPT THUNDER OUT OF THE FORECAST UNTIL VERY LATE
THIS AFTERNOON WHEN THE MODELS INDICATE HIGHER CAPE VALUES WILL
MOVE INTO THE FORECAST AREA WITH THE LIFTING WARM FRONT.

UPDATE ISSUED AT 717 AM CDT WED SEP 18 2013

UPDATED FOR AVIATION DISCUSSION.

&&

.SYNOPSIS...
ISSUED AT 320 AM CDT WED SEP 18 2013

WARM ADVECTION PATTERN CONTINUES ACROSS THE NRN PLAINS AND EAST
INTO THE WRN GT LAKES. ALOFT A WEAK WESTERLY FLOW STRETCHES FROM
THE DAKOTAS INTO THE GT LAKES. A VERY LARGE AREA OF STRATUS WITH
LIGHT RAIN/BR/FG HAS DEVELOPED ACROSS MOST OF THE UPPER MIDWEST.
LATEST SPC MESOANALYSIS SHOWS 85H MSTR TRANSPORT DIRECTED FROM
SWRN MN INTO THE ERN EDGE OF CWA.

&&

.SHORT TERM...(TODAY AND TONIGHT AND TOMORROW)
ISSUED AT 320 AM CDT WED SEP 18 2013

TODAY...TOUGH CALL ON ACTUAL PRECIP OCCURRENCE TODAY. GENERAL IDEA
IS THAT SOME LIGHT RAIN WILL OCCUR ACROSS THE SERN CWA THIS
MORNING. THIS IS ASSOCIATED WITH THE INITIAL 85H MSTR TRANSPORT
AXIS INDUCED BY PASSING SHORTWAVE TROF. AS THE DAY PROGRESSES THE
MID LVL RIDGE AMPLIFIES OVER THE CWA WITH 85H MSTR TRANSPORT
REFORMING SOUTH AND WEST OF CWA. WILL CARRY THE IDEA THAT LOW
CLOUDS WILL BE TOUGH TO SCOUR OUT COMPLETELY BASED ON FCST COND
PRESS DEFICITS FROM HI-RES MDLS. MDL SNDGS SUGGEST SOME ELEVATED
CAPE DEVELOPING LATER THIS MORNING AND LINGERING INTO THE AFTN.
WILL MENTION SLIGHT CHC OF TRW BUT CONFIDENCE NOT VERY HIGH AT THIS
POINT. MORNING BR/FG SHOULD GRADUALLY DECREASE EXCEPT NEAR LAKE
SUPERIOR WHERE HI-RES MDL SUGGEST ONSHORE FLOW WILL CREATE EXTENDED
PERIOD OF BR/FG ESPECIALLY NEAR TWIN PORTS WHERE LONGER NORTHEAST
FETCH INTO THE HEAD OF THE LAKE MAXIMIZES NEAR SFC SATURATION. MAX
TEMPS COULD BE TRICKY TODAY WITH EXTENSIVE CLOUD COVER AND
INCREASINGLY STRONGER NE WIND NEAR LAKE SUPERIOR.

TONIGHT...SFC WARM FRONT MOVES NORTH INTO SRN CWA BY MIDNIGHT AND
THEN TOWARDS IRON RANGE BY EARLY MORNING. BDRY MAY BE SLOWED DOWN
NEAR LAKE SUPERIOR WHERE MARINE LAYER REINFORCES COOL DOME NEAR
SFC. MDLS INDICATE AN ARE OF MID LVL WARMING MOVING INTO WRN/SRN
CWA WHICH MAY LIMIT CONVECTIVE DEVELOPMENT AHEAD OF APPROACHING
COLD FRONT.

TOMORROW...COLD FRONT WILL MOVE ACROSS THE CWA WITH INCREASING
POPS. SPC HAS SLIGHT RISK OF SVR OVER ERN WISC ZONES. HOWEVER SOME
INDICATIONS THAT ACTIVITY OF AN ELEVATED NATURE MAY BE QUITE
ROBUST FARTHER WEST TOWARDS TWIN PORTS/LOWER ST CROIX VALLEY
ALTHOUGH AT THIS TIME HIGHEST DEEP LAYER SHEAR IS LOCATED FARTHER
NORTH OF BEST INSTABILITY. GIVEN NATURE OF ANOMALOUS PWATS AND
FAIRLY SIGNIFICANT FORCING AHEAD/NEAR FRONTAL BDRY SHOULD SEE SOME
LOCALLY HEAVY RAINFALL TOTALS BY LATE THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 AM CDT WED SEP 18 2013

A STRONG COLD FRONT WILL MOVE THROUGH THURSDAY NIGHT...BRINGING
SHOWERS AND THUNDERSTORMS TO THE REGION. SPC HAS A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR EASTERN PORTIONS OF THE CWA...WHICH SOUNDS
REASONABLE GIVEN THE STRENGTH OF THE FRONT AND AVAILABLE MOISTURE.
STRONG CAA WILL PUSH ACROSS THE NORTHLAND BEHIND THE FRONT...WITH
SHOWERS AND THUNDERSTORMS GRADUALLY DIMINISHING FROM WEST TO EAST
THURSDAY NIGHT. WITH A THERMAL TROUGH ACROSS THE CWA ON FRIDAY...
WILL NEED TO HANG ON TO A SMALL CHANCE OF SHOWERS...ESPECIALLY IN
THE NORTH. THE BIG QUESTION IS THE NEXT CHANCE OF FROST. IT LOOKS
LIKE FRIDAY NIGHT WILL LIKELY SEE LINGERING CLOUD COVER AND SOME
WIND INTO THE NIGHT. A MUCH BETTER CHANCE WOULD BE ON SATURDAY
NIGHT...WITH HIGH PRESSURE ACROSS THE REGION. WAA ALREADY STARTS
DURING THE NIGHT...BUT AT LEAST THE ARROWHEAD AND NW WI SHOULD SEE A
CHANCE OF FROST AS SKIES CLEAR ON SATURDAY. WAA WILL BRING WARMER
AIR INTO THE REGION ON SUNDAY...BUT OVERALL IT LOOKS LIKE A
GENERALLY DRY WEEKEND. THE NEXT CHANCE OF PRECIPITATION WOULD ARRIVE
ON MONDAY WITH CHANCE POPS CONTINUING INTO MIDWEEK DUE TO WAA AND
MUCH WARMER AIR ACROSS THE REGION. HIGH TEMPERATURES FRIDAY AND
SATURDAY WILL RANGE FROM THE MID 50S NORTH TO THE MID 60S SOUTH.
HIGHS ON SUNDAY AND MONDAY WILL GENERALLY BE IN THE 60S...WITH HIGHS
ON TUESDAY AND WEDNESDAY BACK INTO THE 70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1243 PM CDT WED SEP 18 2013

IFR OR LOW MVFR CEILINGS/VSBYS COVERED THE NORTHLAND EARLY THIS
AFTERNOON WITH SOME DRIZZLE. CEILINGS/VSBYS WILL SLOWLY INCREASE THROUGH
THE AFTERNOON...BUT STILL REMAIN IFR/MVFR FOR MOST AREAS. AREAS
AROUND LAKE SUPERIOR WILL SEE THE LOWEST CEILINGS/VSBYS AND THE
BEST CHANCE FOR DRIZZLE. VISIBLE SATELLITE IMAGERY SHOWED CLEARING
OCCURRING ACROSS FAR SOUTHWEST MINNESOTA AND THE RAP CONDENSATION
PRESSURE DEFICITS WERE DOING A DECENT JOB WITH THESE LOW CLOUDS.
IT SUGGESTS THIS CLEARING WILL CONTINUE NORTHEAST THIS
AFTERNOON...AFFECTING KBRD LATE THIS AFTERNOON/EARLY EVENING.
CONFIDENCE IN THE CLEARING MAKING IT TOO MUCH FURTHER NORTH AND
EAST IS LOW...AND WE KEPT THE LOWER CLOUDS IN THE REST OF THE
TAFS...AND LOWERED VSBYS LATER THIS EVENING. THE MOIST AIRMASS
WILL REMAIN IN PLACE THROUGH THE PERIOD.

A COLD FRONT WILL INTO THE RED RIVER VALLEY LATE TONIGHT. SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE ALONG AND AHEAD OF THE FRONT
AND WE HIGHLIGHTED THE BEST CHANCE FOR THAT IN THE TAFS. SOME OF
THE STORMS COULD BE QUITE STRONG LATE TONIGHT INTO THURSDAY. ADJUSTMENTS
TO THE TIMING WILL LIKELY BE NEEDED LATER TONIGHT. SOME OF THE
CAMS SUGGEST THERE WILL BE A LINE THAT MOVES THROUGH...WHICH WOULD
BE A RELATIVELY SHORT DURATION EVENT...WHILE THE DETERMINISTIC
MODELS SUGGEST THE PRECIP WILL BE GREATER IN COVERAGE AND LAST
LONGER.

&&

.MARINE...
ISSUED AT 1243 PM CDT WED SEP 18 2013

WE UPDATED THE WINDS OVER LAKE SUPERIOR AND INCREASED THEM A BIT
MORE FROM ABOUT SILVER BAY TO THE TWIN PORTS TO PORT WING.
PRESSURE FALLS TO THE SOUTHWEST AND A TIGHTENING GRADIENT SHOULD
ALLOW WINDS TO PICK UP AND BE SUSTAINED AROUND 15 KNOTS LATER THIS
AFTERNOON INTO THE EVENING. WE KEPT WAVES FROM 2 TO 4 FEET...BUT
SMALL CRAFT ADVISORY THRESHOLDS MAY BE REACHED BRIEFLY LATE
TONIGHT INTO EARLY EVENING. WE`LL MONITOR WINDS/WAVES FROM THE
BUOYS/LAND OBS AND ADJUST AS NEEDED.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  64  61  73  51 /  20  50  70  40
INL  71  61  72  48 /  20  50  70  40
BRD  74  64  74  50 /  20  40  60  10
HYR  71  63  77  51 /  30  40  70  50
ASX  68  60  78  53 /  20  40  70  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&

$$

UPDATE...GROCHOCINSKI
SYNOPSIS...CANNON
SHORT TERM...CANNON
LONG TERM...DAP
AVIATION...MELDE
MARINE...MELDE







AREA FORECAST DISCUSSION

NWS TWIN CITIES/CHANHASSEN MN

 601 AM CDT WED SEP 18 2013

.UPDATED FOR 12Z AVIATION DISCUSSION...
ISSUED AT 547 AM CDT WED SEP 18 2013

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT WED SEP 18 2013

AN AREA OF LOW PRESSURE WAS LOCATED OVER THE WESTERN DAKOTAS...WITH
HIGH PRESSURE ACROSS THE EASTERN SEABOARD. THIS SETUP RESULTED IN
SOUTHERLY FLOW ACROSS THE UPPER MIDWEST WAS BRINGING WARM MOIST AIR
TO THE REGION. THIS WAA WAS EASILY IDENTIFIED BY LOOKING AT THE H850
TEMPERATURE ADVECTION OFF THE SPC MESOANALYSIS PAGE. THE LOW LEVEL
MOISTURE WAS EVIDENT BY THE STRATUS DECK THAT COVERED THE ENTIRE
UPPER MISSISSIPPI RIVER VALLEY WITH POCKETS OF DRIZZLE AND FOG. A
FEW AREAS OF ELEVATED CONVECTION MANAGED TO DEVELOP ALONG THE
EAST/WEST MUCAPE GRADIENT. SINCE THESE STORMS WERE ELEVATED...THEY
WERE UNABLE TO TAKE ADVANTAGE OF THE 0-1KM SHEAR AND HELICITY OF
30KTS AND 300M2/S2 RESPECTIVELY...AND DRIFTED HARMLESSLY EAST
NORTHEAST WITH THE MEAN WIND.

MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING HOW THE STATUS FIELD
WILL EVOLVE TODAY. H850 TEMPS WILL INCREASE FROM AROUND 12-15C EARLY
THIS MORNING...TO 20-22C THIS AFTERNOON. THAT WARM LAYER ALOFT WILL
ONLY ENHANCE THE CAPPING INVERSION AND LIMIT MIXING THIS AFTERNOON.
AS A RESULT IT MAY BE DIFFICULT TO LOOSE THE CLOUDS...WHICH IN TURN
WILL HAMPER TODAYS HIGH TEMPERATURES. MOST LIKELY IT WILL EITHER BE
BOOM OR BUST WITH HIGHS TODAY. THE NAM AND HRRR CLEAR OUT THE
CLOUDS BY EARLY THIS AFTERNOON WHICH WOULD FAVOR A WARMER SOLUTION.
HOWEVER...JUST WITHIN THE INDIVIDUAL MEMBERS OF THE SREF THE HIGH
TEMPERATURE TODAY VARIES FROM 89 TO 77 AT KMSP. MEMBER 2 OF THE
HOPWRF KEEPS THE CLOUDS ACROSS THE CWA THROUGH 21Z THIS
AFTERNOON...SO HAVE TRENDED BACK TEMPERATURES SLIGHTLY TO REFLECT
THE MORE CLOUDY SCENARIO. AS THE WARM FRONT LIFT NORTHWARD THIS
AFTERNOON AND OVERNIGHT PRECIP CHANCES WILL DECREASE FROM SOUTH TO
NORTH...BUT RETURN AGAIN EARLY THURSDAY MORNING AS THE COLD FRONT
APPROACHES FROM THE WEST.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 328 AM CDT WED SEP 18 2013

SHOWERS AND SOME THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE
FAR EASTERN DAKOTAS AND WESTERN MINNESOTA THURSDAY MORNING. MOIST
SOUTHERLY FLOW WITH PW VALUES OF 1.5 TO 1.8 INCHES...ROUGHLY 220
PERCENT OF NORMAL...AND 850 MB TEMPS OF +20C WILL OVERSPREAD THE
REGION. THE CAPPING INVERSION PRODUCED BY THIS ABUNDANCE OF WARM
AIR ALOFT WILL LIKELY CONTRIBUTE TO CONSIDERABLE CLOUDINESS
THROUGH MUCH OF THE DAY WITH LITTLE HOPE OF DEEP MIXING AND
ERODING THE CAP SUFFICIENTLY AHEAD OF THE FRONT. THIS WILL PROVE
DETRIMENTAL ON WIDESPREAD CONVECTIVE CHANCES TO SOME
DEGREE...UNLESS SURFACE TEMPS DO WARM INTO THE 80S. BEST POTENTIAL
FOR THIS WOULD BE ACROSS WESTERN WI AS FROPA WILL TAKE PLACE LATE
IN THE DAY. MID LEVEL LAPSE RATES WILL CONTRIBUTE TO AROUND 2000
J/KG MLCAPE...SO IF THE CAP DOES ERODE...WIDESPREAD THUNDERSTORMS
CAN BE EXPECTED. MODEST SPEED SHEAR WOULD ALSO HELP ORGANIZE A FEW
STORMS ENOUGH FOR A MARGINAL SEVERE THREAT.

COOLER AND DRIER AIR WILL FOLLOW THURSDAY NIGHT INTO SATURDAY. AS
THE HIGH PUSHES OVERHEAD FRIDAY NIGHT...TEMPERATURES COULD FALL
INTO THE 30S IN SOME LOCATIONS IF WINDS DECOUPLE.

RETURN FLOW WILL COMMENCE SATURDAY NIGHT AND STRENGTHEN INTO EARLY
NEXT WEEK AS TROUGHING DIGS INTO THE PACIFIC NORTHWEST. SOUTHWEST
FLOW WILL KEEP THE STORM TRACK WEST OF THE REGION...AND COLD
FRONTS/DISTURBANCES PUSHING THROUGH WILL NOT HAVE MUCH PUNCH. ONE
SUCH FRONT IS PROGGED FOR MONDAY AND MONDAY NIGHT...WITH THE ECMWF
THE STRONGEST OF ALL GUIDANCE. ONLY LOW POPS WERE JUSTIFIED.
TEMPERATURES WILL BE ABOVE AVERAGE EARLY NEXT WEEK...AND 80S MAY
RETURN FOR MIDWEEK WITH 925 MB TEMPS CLIMBING INTO THE 20S C.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 547 AM CDT WED SEP 18 2013
AN AREA OF LOW PRESSURE WAS LOCATED OVER THE DAKOTAS...WITH
SOUTHERLY FLOW AND LOW CLOUDS ACROSS MN/WI. THE LIFR STRATUS WILL
LINGER ACROSS THE REGION THIS MORNING...AND ERODE FROM THE SOUTH
THIS AFTERNOON. LATER TONIGHT WILL LIKELY SEE LIFR CONDITIONS
AGAIN ALONG THE APPROACHING FRONTAL BOUNDARY. THIS FRONT WILL BE
THE FOCUS FOR A FEW SHOWERS AND THUNDERSTORMS AS WELL EARLY
THURSDAY MORNING.

KMSP...
FORECAST GUIDANCE CONTINUE TO SHOW LIFR CONDITIONS PREVAILING THIS
MORNING...WITH A SLIGHT IMPROVEMENT TO IFR BY LATE MORNING. THE
HOPWRF HIRES MODEL ERODES THE STRATUS FROM THE SOUTHWEST...AND THE
CLEARING SHOULD REACH THE METRO AREA AROUND 20Z. WINDS WILL BE
SOUTH SOUTHEASTERLY TODAY. A COLD FRONT WILL APPROACH FROM THE
WEST THURSDAY MORNING...AND BRING A CHANCE FOR SHOWERS AND
THUNDERSTORMS.

/OUTLOOK FOR KMSP/
FRI...VFR. WINDS NW 15G25KT.
SAT...VFR. WINDS NW 5-10KT.
SUN...VFR. WINDS SE AT 15G20KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JRB







AREA FORECAST DISCUSSION

NWS TWIN CITIES/CHANHASSEN MN

 328 AM CDT WED SEP 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT WED SEP 18 2013

AN AREA OF LOW PRESSURE WAS LOCATED OVER THE WESTERN DAKOTAS...WITH
HIGH PRESSURE ACROSS THE EASTERN SEABOARD. THIS SETUP RESULTED IN
SOUTHERLY FLOW ACROSS THE UPPER MIDWEST WAS BRINGING WARM MOIST AIR
TO THE REGION. THIS WAA WAS EASILY IDENTIFIED BY LOOKING AT THE H850
TEMPERATURE ADVECTION OFF THE SPC MESOANALYSIS PAGE. THE LOW LEVEL
MOISTURE WAS EVIDENT BY THE STRATUS DECK THAT COVERED THE ENTIRE
UPPER MISSISSIPPI RIVER VALLEY WITH POCKETS OF DRIZZLE AND FOG. A
FEW AREAS OF ELEVATED CONVECTION MANAGED TO DEVELOP ALONG THE
EAST/WEST MUCAPE GRADIENT. SINCE THESE STORMS WERE ELEVATED...THEY
WERE UNABLE TO TAKE ADVANTAGE OF THE 0-1KM SHEAR AND HELICITY OF
30KTS AND 300M2/S2 RESPECTIVELY...AND DRIFTED HARMLESSLY EAST
NORTHEAST WITH THE MEAN WIND.

MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING HOW THE STATUS FIELD
WILL EVOLVE TODAY. H850 TEMPS WILL INCREASE FROM AROUND 12-15C EARLY
THIS MORNING...TO 20-22C THIS AFTERNOON. THAT WARM LAYER ALOFT WILL
ONLY ENHANCE THE CAPPING INVERSION AND LIMIT MIXING THIS AFTERNOON.
AS A RESULT IT MAY BE DIFFICULT TO LOOSE THE CLOUDS...WHICH IN TURN
WILL HAMPER TODAYS HIGH TEMPERATURES. MOST LIKELY IT WILL EITHER BE
BOOM OR BUST WITH HIGHS TODAY. THE NAM AND HRRR CLEAR OUT THE
CLOUDS BY EARLY THIS AFTERNOON WHICH WOULD FAVOR A WARMER SOLUTION.
HOWEVER...JUST WITHIN THE INDIVIDUAL MEMBERS OF THE SREF THE HIGH
TEMPERATURE TODAY VARIES FROM 89 TO 77 AT KMSP. MEMBER 2 OF THE
HOPWRF KEEPS THE CLOUDS ACROSS THE CWA THROUGH 21Z THIS
AFTERNOON...SO HAVE TRENDED BACK TEMPERATURES SLIGHTLY TO REFLECT
THE MORE CLOUDY SCENARIO. AS THE WARM FRONT LIFT NORTHWARD THIS
AFTERNOON AND OVERNIGHT PRECIP CHANCES WILL DECREASE FROM SOUTH TO
NORTH...BUT RETURN AGAIN EARLY THURSDAY MORNING AS THE COLD FRONT
APPROACHES FROM THE WEST.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 328 AM CDT WED SEP 18 2013

SHOWERS AND SOME THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS THE
FAR EASTERN DAKOTAS AND WESTERN MINNESOTA THURSDAY MORNING. MOIST
SOUTHERLY FLOW WITH PW VALUES OF 1.5 TO 1.8 INCHES...ROUGHLY 220
PERCENT OF NORMAL...AND 850 MB TEMPS OF +20C WILL OVERSPREAD THE
REGION. THE CAPPING INVERSION PRODUCED BY THIS ABUNDANCE OF WARM
AIR ALOFT WILL LIKELY CONTRIBUTE TO CONSIDERABLE CLOUDINESS
THROUGH MUCH OF THE DAY WITH LITTLE HOPE OF DEEP MIXING AND
ERODING THE CAP SUFFICIENTLY AHEAD OF THE FRONT. THIS WILL PROVE
DETRIMENTAL ON WIDESPREAD CONVECTIVE CHANCES TO SOME
DEGREE...UNLESS SURFACE TEMPS DO WARM INTO THE 80S. BEST POTENTIAL
FOR THIS WOULD BE ACROSS WESTERN WI AS FROPA WILL TAKE PLACE LATE
IN THE DAY. MID LEVEL LAPSE RATES WILL CONTRIBUTE TO AROUND 2000
J/KG MLCAPE...SO IF THE CAP DOES ERODE...WIDESPREAD THUNDERSTORMS
CAN BE EXPECTED. MODEST SPEED SHEAR WOULD ALSO HELP ORGANIZE A FEW
STORMS ENOUGH FOR A MARGINAL SEVERE THREAT.

COOLER AND DRIER AIR WILL FOLLOW THURSDAY NIGHT INTO SATURDAY. AS
THE HIGH PUSHES OVERHEAD FRIDAY NIGHT...TEMPERATURES COULD FALL
INTO THE 30S IN SOME LOCATIONS IF WINDS DECOUPLE.

RETURN FLOW WILL COMMENCE SATURDAY NIGHT AND STRENGTHEN INTO EARLY
NEXT WEEK AS TROUGHING DIGS INTO THE PACIFIC NORTHWEST. SOUTHWEST
FLOW WILL KEEP THE STORM TRACK WEST OF THE REGION...AND COLD
FRONTS/DISTURBANCES PUSHING THROUGH WILL NOT HAVE MUCH PUNCH. ONE
SUCH FRONT IS PROGGED FOR MONDAY AND MONDAY NIGHT...WITH THE ECMWF
THE STRONGEST OF ALL GUIDANCE. ONLY LOW POPS WERE JUSTIFIED.
TEMPERATURES WILL BE ABOVE AVERAGE EARLY NEXT WEEK...AND 80S MAY
RETURN FOR MIDWEEK WITH 925 MB TEMPS CLIMBING INTO THE 20S C.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1040 PM CDT TUE SEP 17 2013

LIFR CIGS AND IFR VSBYS CONTINUE TO SPREAD NORTH INTO CENTRAL MN
LATE THIS EVENING. THE MN TAF SITES WILL EXPERIENCE CIGS AT OR
BELOW 005 FOR THE OVERNIGHT THROUGH MID MORNING HOURS ON WED.
VSBYS WILL BE 1-3SM IN -DZ/-RA/BR. THESE CONDITIONS WILL SPREAD
INTO KRNH AND KEAU...IT WILL JUST TAKE A LITTLE LONGER. THERE
REMAINS THE THREAT OF THUNDER... PRIMARILY FROM KMSP ON EAST AND
SOUTH OVERNIGHT AS THE LOW LEVEL JET/MOISTURE TRANSPORT/
INSTABILITY GRADIENT MOVE THROUGH IN THE 08Z-13Z TIME FRAME. VCTS
REMAIN IN FOR KMSP... KRNH AND KEAU. TIMING ON LIFTING THE CEILINGS
AND VSBYS BACK TO VFR REMAINS ABOUT THE SAME FROM THE PREVIOUS TAF
PACKAGE WITH CLEARING MOVING FROM KRWF LATE IN THE MORNING TO KEAU
BY LATE IN THE AFTERNOON. SE WINDS NEAR 10 KNOTS THROUGH MUCH OF
THE PERIOD. THE WINDS WILL BE A LITTLE STRONGER (15G22KTS) FOR KRWF
AND KAXN WEDNESDAY AFTERNOON ALONG WITH MORE OF A SOUTHERLY
DIRECTION (170).

KMSP...CEILINGS CONTINUING A DOWNWARD TREND OVERNIGHT REACHING
004-005 BY WED MORNING. -RA/-DZ AT THE START OF THE TAF WILL GIVE
WAY TO SOME SHOWERS OVERNIGHT AND EARLY WED MORNING. A THUNDERSTORM
REMAINS POSSIBLE IN THE 08Z-11Z TIME FRAME. CEILINGS SHOULD BE
SLOW TO LIFT WEDNESDAY MORNING WITH A BREAKOUT TO VFR STILL
EXPECTED BY 21Z.

/OUTLOOK FOR KMSP/
THU...MVFR CIGS WITH SHRA/TSRA. WINDS S 10 KTS BCMG W IN THE AFTN.
FRI...VFR. WINDS NW 15G25 KTS.
SAT...VFR. WINDS NW 5-10 KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...RAH








AREA FORECAST DISCUSSION

NWS DULUTH MN

 1255 AM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 1253 AM CDT WED SEP 18 2013

UPDATED FOR AVIATION DISCUSSION

UPDATE ISSUED AT 645 PM CDT TUE SEP 17 2013

HAVE UPDATED SKY CONDITIONS FOR A MORE OVERCAST OVERNIGHT
FORECAST...AND A DELAY IN CLEARING FOR WEDNESDAY MORNING.
OTHERWISE LITTLE/NO CHANGE TO CURRENT FORECAST.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 318 PM CDT TUE SEP 17 2013

MOISTURE CONTINUED TO INCREASE FROM WEST TO EAST ACROSS THE
NORTHLAND TODAY. THE HIGH TO THE EAST WAS LOSING IT`S GRIP ON THE
NORTHLAND. A SHORTWAVE WAS MOVING NORTHEAST OUT OF IOWA AND WILL
COMBINE WITH WAA/MOISTURE ADVECTION TO CAUSE CLOUDS TO THICKEN ALL
AREAS TONIGHT AND BRING A CHANCE FOR RAIN. THE RAP WAS DOING A
GOOD JOB DEPICTING THE CLOUDS OVER OUR WESTERN CWA AND THEY SHOW
INCREASING HUMIDITY ACROSS MUCH OF THE AREA BY 06Z. RAIN WILL BE
POSSIBLE TONIGHT...AND WE INCREASED POPS OVER OUR FAR SOUTHERN CWA
WHICH WILL HAVE THE BEST CHANCE AT SEEING UP TO A TENTH OF AN INCH
OVERNIGHT. PWAT VALUES ARE EXPECTED TO RISE TO 1 TO 1.4 INCHES
OVERNIGHT...AND WE EXPECT AREAS OF FOG TO FORM. MOST AREAS SHOULD
NOT EXPERIENCE DENSE FOG...WITH THE EXCEPTION OF AREAS AROUND LAKE
SUPERIOR LATE TONIGHT WHICH COULD SEE SOME PATCHY DENSE FOG. SURFACE
DEWPOINTS ARE EXPECTED TO RISE INTO THE FIFTIES...AND WERE ALREADY
50 TO 55 FROM KINL TO KGPZ TO KAIT AND POINTS WEST. WE KEPT THE
MENTION OF DRIZZLE TONIGHT FOR MOST AREAS...ALTHOUGH WE DON`T
THINK IT WILL BE WIDESPREAD GIVEN UPSTREAM CONDITIONS. AREAS
AROUND THE LAKE WILL HAVE A BETTER CHANCE AND IT COULD BE
WIDESPREAD LATE TONIGHT INTO WEDNESDAY MORNING.

STABILITY GRADUALLY LOWERS TONIGHT...AND WE ADDED A SLIGHT CHANCE
FOR A THUNDERSTORM ACROSS THE SOUTH LATE. WAA WILL CONTINUE
WEDNESDAY...WITH A SHORTWAVE RIDGE ALOFT MOVING THROUGH EARLY.
WE HAVE A CHANCE FOR MORE SHOWERS/STORMS OVER ALL BUT FAR
NORTHWEST AREAS ON WEDNESDAY...WITH THE BEST CHANCE OCCURRING
EARLY. CLOUDS WILL SLOWLY DIMINISH OVER WESTERN AREAS...BUT
SHOULD REMAIN THROUGH MOST OF THE DAY AROUND LAKE SUPERIOR AND
OVER NORTHWEST WISCONSIN. HIGHS WILL RANGE FROM THE MID SIXTIES TO
MID SEVENTIES ACROSS THE NORTHLAND...WARMEST SOUTHWEST...COOLEST
AROUND LAKE SUPERIOR.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 318 PM CDT TUE SEP 17 2013

THE FIRST FEW DAYS OF THIS PERIOD WILL BE STORMY AND WET THEN BECOME
CHILLY WITH A STRONG COLD FRONTAL PASSAGE.

STRONG WAA THAT WILL BE ONGOING AHEAD OF AN APPROACHING COLD FRONT
WILL CONTINUE CLOUDS WEDNESDAY NIGHT. KEPT IN CHANCE OF SHOWERS
AND THUNDERSTORMS WEDNESDAY NIGHT...BUT VERY WARM MID LEVEL TEMPS
MAY PROHIBIT STORM FORMATION. BOTH THE NAM AND GFS SHOW SURGE OF 7H
10+C TEMPS. MUCH BETTER CHANCE OF THUNDERSTORMS WILL BE THURSDAY AS
A STRONG COLD FRONT APPROACHES THE AREA FROM THE WEST. THE NAM MAY BE
A BIT FASTER...BUT THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH
MOVEMENT OF THE FRONT AND RESULTING QPF. DURING THE DAY THE
ATMOSPHERE DESTABILIZES IN THE STRONG WAA REGIME AND WILL BE PRIMED
FOR STORMS WHEN THE FRONT ARRIVES IN THE AFTERNOON/EARLY EVENING
EVENING. LIL`S FORECAST DOWN TO -6 AND MUCAPES UP TO 2500 J/KG.  AN
EXTRA BOOST OF LIFT WILL BE PROVIDED BY AN UPPER LEVEL JET AND
S/WV.

STRONG COLD AIR WILL STREAM INTO THE REGION BEHIND THE FRONT FOR THE
FRIDAY...BUT AS HIGH PRESSURE BUILDS INTO THE REGION THE WEEKEND
WILL HAVE SUNSHINE BUT COOLER TEMPS. THIS WILL BE FOLLOWED BY
ANOTHER LOW PRESSURE/COLD FRONT ON FROM EARLY THROUGH MID WEEK WITH
A STRONG UPPER LEVEL TROF/CLOSED LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1253 AM CDT WED SEP 18 2013

CONDITIONS TO GRADUALLY DETERIORATE OVER THE NEXT FEW HOURS...WITH
CIGS AND VSBYS FALLING INTO IFR...POSSIBLY LIFR FOR SEVERAL HOURS
DURING THE EARLY MORNING HOURS GENERALLY BETWEEN 09Z AND 15Z.
CONDITIONS TO BE BETTER FARTHER NORTH...WITH ONLY MVFR CONDITIONS
EXPECTED.  SOUTHERN SITES MOST LIKELY TO DROP TO LIFR WITH -RA OR
-DZ AND FOG WITH VISBYS TO LIFR AT TIMES AS WELL.  CIGS LIKELY TO
LINGER THIS MORNING...WITH CLEARING NOT EXPECTED UNTIL THIS
AFTERNOON.  THIS AFTERNOON IF SOME HOLES CAN DEVELOP IN THE OVERCAST
WE MAY BE ABLE TO DEVELOP SOME SHOWERS WITH ISOLATED THUNDER DURING
THE LATE MORNING AND AFTERNOON...BUT CONFIDENCE IS NOT HIGH AND FOR
NOW HAVE ONLY PUT IN VCSH.  SOME CLEARING SHOULD OCCUR BY LATE
AFTERNOON...ONLY TO FILL IN AGAIN DURING THE EVENING AS THE COLD
FRONT MOVES INTO THE AREA FROM THE WEST.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  62  74  51  61 /  50  70  30  20
INL  60  71  49  56 /  50  60  30  30
BRD  65  74  49  63 /  50  60  10  10
HYR  62  76  49  64 /  40  70  30  10
ASX  59  78  51  63 /  40  70  40  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&

$$

UPDATE...DAP/LE
SHORT TERM...MELDE
LONG TERM...CLC
AVIATION...LE







AREA FORECAST DISCUSSION...UPDATED

NWS BILLINGS MT

 919 PM MDT THU SEP 19 2013

.UPDATE...
CLOUDS HAVE DECREASED WITH THE SETTING SUN AS EXPECTED. DEWPOINTS
REMAIN IN THE UPPER 30S TO AROUND 40 DEGREES. WINDS WERE LIGHT
ACROSS THE FORECAST AREA AND THESE FACTORS COULD LEAD TO SOME FOG
OR EVEN FROST FORMATION LATE TONIGHT AND TOWARD MORNING. THIS
COVERED IN EXISTING FORECAST. TEMPERATURES LOOK IN GOOD SHAPE. NO
CHANGES. TWH

&&

.SHORT TERM...VALID FOR FRI AND SAT...

UPPER TROF CONTINUES TO SHIFT EAST AND WE ARE BEGINNING TO SEE
HEIGHT RISES INTO CENTRAL MT. SOME LIGHT SHOWERS REMAIN EAST OF
MILES CITY...ASSOCIATED WITH WEAK SHORTWAVE EMBEDDED IN THE NW
FLOW ALOFT...BUT THIS ACTIVITY IS WEAKENING AND WILL BE DONE
BEFORE 00Z.

ISSUES FOR TONIGHT INCLUDE FOG AND FROST POTENTIAL. PLENTY OF
CLOUD COVER CURRENTLY EXISTS IN OUR EAST BUT THIS WILL BE
DISSIPATING INTO THE EVENING. CURRENT DEWPTS ARE NOTEWORTHY...IN
THE UPPER 30S TO AROUND 40...AND WILL NOT SEE ANY SIGNIFICANT LOW
LEVEL DRYING IN OUR EAST BEFORE SUNSET. WITH THIS IN MIND...AND AS
SFC RIDGE BUILDS TO THE SOUTHEAST ALLOWING FOR THE NWLY GRADIENT
TO RELAX...BELIEVE SOME FOG OR STRATUS DEVELOPMENT IS POSSIBLE IN
OUR EAST. MIGHT LEAN TOWARD PATCHY VALLEY FOG HERE AS RAP SHOWS A
DECENT NW WIND AT 850MB THRU 12Z. WITHOUT ANY STRATUS BELIEVE SOME
AREAS IN OUR FAR EAST WILL SEE SOME FROST WITH TEMPS INTO THE MID
30S TONIGHT. IN OUR WEST...CLEAR SKIES A CERTAINTY WITH ONLY WEAK
DOWNSLOPE GRADIENTS DEVELOPING AFTER MIDNIGHT. SO BELIEVE
NOTORIOUSLY COLDER SPOTS SUCH AS HARLOWTON...LIVINGSTON AND
SHERIDAN WILL SEE SOME FROST TONIGHT. DEWPTS ARE PROBABLY TOO HIGH
TO SUPPORT A REAL FREEZE THOUGH. GENERALLY SPEAKING HAVE LOWERED
TEMPS FOR TONIGHT A BIT MORE...AND THIS IS CONSISTENT WITH THE
SLOWER PROGRESSING UPPER TROF AND COOLING TREND IN ALL GUIDANCE.
FOR BILLINGS...COULD SEE MID OR UPPER 30S FOR LOWS ALONG THE
YELLOWSTONE VALLEY...BUT RIDGES SHOULD NOT FALL BELOW THE LOW 40S.

DRY WX WITH A WARMING TREND IN STORE FOR FRI/SAT AS STRONG RIDGE
ALOFT BUILDS OVER THE REGION. EXPECT TEMPS TO CLIMB BACK INTO THE
70S TOMORROW AND 80S ON SAT...WITH GOOD CONFIDENCE IN A STRONG
WARM UP SUPPORTED BY DRY AIRMASS SETTLING IN AND WHAT WILL BE DEW
PTS IN THE 20S AND 30S. DEEPER MIXING OF INCREASED SW WINDS ALOFT
WILL RESULT IN GUSTY WINDS FOR OUR WESTERN FOOTHILLS INCLUDING
LIVINGSTON ON SAT...WHICH WILL COINCIDE WITH AFTN RHS IN THE LOW
TEENS. THESE CONDITIONS WILL BE HIGHLIGHTED IN THE FIRE WEATHER
FORECAST.

NEXT PACIFIC TROF...THOUGH WEAKENING AS IT COMES INLAND...WILL
BEGIN TO IMPACT OUR FAR WEST LATE SAT NIGHT. HAVE SCALED BACK POPS
SLIGHTLY AND PUSHED THEM WEST AFTER 06Z...BASED ON MODEL CONSENSUS
FOR THIS SLOWER TIMING. WEAK COLD FRONT WILL ALLOW FOR COOLER
PACIFIC AIR TO BEGIN SPREADING IN FROM THE WEST LATE SAT NITE...
SETTING UP A COOLER SUNDAY.

JKL

.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...

THE EXTENDED FORECAST LOOKS A LOT MORE LIKE FALL WITH TWO WEATHER
SYSTEMS TO WATCH. THE FIRST SYSTEM WILL IMPACT THE REGION ON
SUNDAY...AND WILL BRING SOME SNOW SHOWERS TO HIGH ELEVATIONS IN
THE MOUNTAINS AND RAIN SHOWERS ACROSS THE REST OF THE FORECAST
AREA...BRINGING TEMPERATURES BACK TO NEAR SEASONAL NORMALS. THE
SECOND SYSTEM...WHICH IS MUCH MORE INTERESTING...WILL IMPACT THE
REGION BY WEDNESDAY AND THURSDAY...AND WILL BRING MUCH BELOW
NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD PRECIPITATION.

...SUNDAY THROUGH TUESDAY...
A SPLITTING TROUGH WILL CROSS THE REGION ON SUNDAY...BRINGING AN
INCREASE IN PACIFIC MOISTURE AND QG FORCING ACROSS THE FORECAST
AREA. ELEVATED MOUNTAIN LOCATIONS WILL LIKELY CATCH SOME SNOW
SHOWERS WITH THIS SYSTEM AS H7 TEMPS DECREASE TO AROUND 0C. WINDS
WILL REMAIN MOSTLY WESTERLY AND DOWNSLOPE...WHICH WILL ACT TO
LIMITE THE AMOUNT OF PRECIPITATON ACROSS THE PLAINS LOCATIONS.
HOWEVER...FULLY EXPECT A COOLER AND CLOUDY DAY WITH SCATTERED RAIN
SHOWERS ACROSS THE PLAINS. THE FLOW BEHIND THE WAVE FOR MONDAY AND
TUESDAY WILL REMAIN NEAR ZONAL WITH THE JET OVERHEAD...KEEPING
TEMPERATURES NEAR NORMAL AND A CHANCE OF SOME SHOWERS IN THE
MOUNTAINS...OTHERWISE THE REMAINDER OF THE FORECAST AREA SHOULD
STAY DRY.

...WEDNESDAY AND THURSDAY...
GLOBAL MODELS ARE EXTREMELY CONSISTENT WITH THE WEATHER PATTERN
OVER THE PACIFIC BY THIS TIME FRAME...AND ALL DEVELOP A DIGGING
TROUGH DOWN THE WEST COAST BY TUESDAY INTO WEDNESDAY. THE PATTERN
WILL OPEN THE DOOR TO MUCH COOLER TEMPERATURES FOR WEDNESDAY AND
THURSDAY. WHILE THERE ARE MINOR DIFFERENCES IN THE EVOLUTION OF
THE TROUGH...BOTH THE GFS AND ECMWF POSITION THE LOW JUST TO OUR
WEST BY WEDNESDAY AFTERNOON AND SLIDE THE LOW ACROSS OUR SOUTH BY
THURSDAY. THIS SOLUTION IS FAVORABLE FOR A PROLONGED UPSLOPE
EVENT. THAT COMBINED WITH THE DYNAMICS OF THE LOW COULD PRODUCE A
WIDESPREAD PRECIPITATION EVENT ACROSS THE AREA...AND IN PARTICULAR
ALONG THE FOOTHILLS AND EAST FACING MOUNTAIN LOCATIONS.
TEMPERATURES ARE COOL ENOUGH THAT SNOW IN THE MOUNTAINS WOULD BE
LIKELY AND COULD GET INTO HIGH FOOTHILLS LOCATIONS. TEMPERATURES
ACROSS THE PLAINS WOULD CERTAINLY BE THE COOLEST WE HAVE SEEN THIS
FALL...BUT AT THIS POINT LOOK JUST WARM ENOUGH FOR MAINLY RAIN
EVENT. THIS WEATHER SYSTEM WILL BE THE ONE TO WATCH AS IT BECOMES
CLOSER IN TIME.

CHURCH
&&

.AVIATION...

VFR WILL PREVAIL ACROSS THE AREA TONIGHT THROUGH FRI. SOME PATCHY
VALLEY FOG WILL BE POSSIBLE E OF KBIL LATE TONIGHT THROUGH EARLY
FRI MORNING. ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    FRI     SAT     SUN     MON     TUE     WED     THU
-----------------------------------------------------------
BIL 043/075 050/084 054/069 048/071 048/068 047/055 043/052
    00/U    00/U    12/T    11/B    02/T    23/W    44/W
LVM 034/078 042/086 047/065 042/068 043/065 043/048 038/047
    00/U    00/N    22/T    11/B    12/T    23/W    44/W
HDN 038/078 046/086 051/073 046/073 045/073 047/059 044/054
    00/U    00/U    02/T    21/B    01/B    13/W    44/W
MLS 040/075 049/084 054/075 051/075 050/075 050/063 047/057
    00/U    00/U    02/T    21/U    11/B    13/W    44/W
4BQ 038/074 044/084 053/076 046/074 046/074 047/065 046/056
    00/U    00/U    02/T    21/U    11/U    12/W    33/W
BHK 036/070 043/080 050/077 046/073 044/075 045/064 048/057
    00/U    00/U    02/T    21/U    11/U    12/W    44/W
SHR 035/076 045/084 050/072 044/071 045/073 044/060 042/051
    00/U    00/U    02/T    30/U    01/U    12/W    44/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS




AREA FORECAST DISCUSSION

NWS BILLINGS MT

 1103 AM MDT WED SEP 18 2013

.UPDATE...

HAVE UPDATED AGAIN TO RAISE TEMPS PER PREFRONTAL WARMING AND
DOWNSLOPE WINDS. BAND OF SHOWERS FROM LVM TO 3HT HAS SLOWED IN
RESPONSE TO 95KT SWLY JET ALOFT. WATER VAPOR SHOWS DRY SLOTTING
INTO OUR BEARTOOTH FOOTHILLS...AND HAVE RAISED WIND GUSTS IN THIS
AREA AND OVER THE BIG HORNS FOR THE NEXT FEW HOURS. SOLAR HEATING
WILL HELP OUR CONVECTIVE CHANCES THIS AFTERNOON. TEMPS FALLING
SIGNIFICANTLY BEHIND COLD FRONT...LVM REACHED 62F BUT HAS SINCE
FALLEN TO 48F...SO HEADS UP EVERYONE. JKL


UPPER LOW CONTINUES TO APPROACH OUR REGION FROM THE WEST. 95KT H3
JET CURRENTLY LIFTING FROM SE ID INTO NW WY IS PROVIDING UPPER
SUPPORT...AND LINE OF SHOWERS WITH EMBEDDED TSTMS HAS FORMED ALONG
SFC FRONT IN SOUTH CENTRAL MT AND IS NEAR A 3HT TO LVM LINE AS OF
1530Z...MOVING SLOWLY EAST. HIGHWAY 212 HAS BEEN CLOSED OVER
BEARTOOTH PASS PER SOME WET SNOW OVER 9KFT OR SO. FISHER CK SNOTEL
AT 9100 FEET IS CURRENTLY 36F.

FORECAST IS ON TRACK AND HAVE MADE NO SIGNIFICANT CHANGES THIS
MORNING. EASTERN PARTS HAVE CLEARED SO HAVE REDUCED SKY COVER AND
POPS TIL 18Z...AND HAVE ALSO RAISED TEMPS A LITTLE PER THE SUN AND
WEST WINDS. MORNING DESTABILIZING SHOULD BE FOLLOWED BY SOME
STRONGER STORMS IN OUR EAST THIS AFTERNOON AS ASCENT INCREASES...
AND THIS INDEED IS WHAT THE LATEST HRRR IS HINTING AT. TSTMS WILL
BE MORE ISOLD WITH GENERALLY SHOWERY/COOLER WEATHER OUT WEST. 12Z
BOISE RAOB SHOWS 500MB OF -20C AND 700MB TEMP OF -5C...CONTINUING
THE TREND OF COLDER MID AND UPPER LEVEL TEMPS FURTHER SOUTH AS THE
TROF PUSHES THROUGH THE NORTHERN ROCKIES...AND THIS IS CONSISTENT
WITH A MORE AMPLIFIED UPPER JET. ALL THAT BEING SAID...SHOWER
ACTIVITY WILL CONTINUE THROUGH THE DAY AND INTO TONIGHT...WITH
SNOW LEVELS LIKELY TO DROP TO AROUND 8KFT. STRONGER DESCENT AND
LOW LEVEL DOWNSLOPE WINDS WILL REDUCE OUR PCPN CHANCES
SIGNIFICANTLY AFTER 00Z. HAVE RAISED WESTERN POPS THROUGH THE
AFTERNOON THOUGH BASED ON ASCENT...POST FRONTAL MOISTURE AND
COOLING ALOFT.

JKL

&&

.SHORT TERM...VALID FOR TDY AND THU...

PASSAGE OF THE LONG-ADVERTISED UPPER-LEVEL TROUGH IS STILL SET FOR
TODAY...BUT SOME UNCERTAINTY REMAINS IN PRECIPITATION COVERAGE. WE
HAVE MUCH MORE CONFIDENCE IN THE ARRIVAL OF COOL TEMPERATURES.

TODAY...FORCING FOR ASCENT SIMULATED BY MODEL 500-300 HPA Q-VECTOR
FIELDS IS BEING MANIFEST AS RAINFALL IN SOUTHEASTERN ID ALREADY AS
OF 09 UTC. WE EXPECT THAT VERTICAL MOTION AND PRECIPITATION TO GET
UP INTO SOUTH CENTRAL MT THIS MORNING...SO LIKELY POPS REMAIN FROM
COOKE CITY AND LIVINGSTON AND ALL THE WAY UP TO HARLOWTON. THAT IS
SUPPORTED BY ENSEMBLE OUTPUT INCLUDING THE 21 UTC SREF. CONFIDENCE
IS LOWER THAT ANYTHING MORE THAN SCATTERED SHOWERS WILL OCCUR EAST
OF THERE IN PLACES LIKE BILLINGS TODAY BECAUSE MODELS ALL SIMULATE
SUBSIDENCE FROM NEAR THE SURFACE TO 500 HPA...WITH DOWNSLOPE WINDS
AIDING THAT PROCESS BY AFTERNOON TOO. THE DOWNSLOPE SIGNATURE WILL
WEAKEN FROM BIG HORN COUNTY AND INTO SOUTHEASTERN MT...SO POPS ARE
HIGHER /IN THE 50 PERCENT RANGE/ THIS AFTERNOON IN THOSE AREAS. IT
LOOKS LIKE STORMS MAY ACTUALLY FIRE FROM BIG HORN COUNTY EAST OVER
INTO SOUTHEASTERN MT AFTER 18 UTC AS HEIGHT FALLS OCCUR ALOFT WITH
A MODERATELY UNSTABLE BOUNDARY LAYER. FORECAST SOUNDINGS IN PLACES
LIKE EKALAKA SHOW MLCAPE UP TO 800 J/KG AND 50 KT MID-LEVEL WINDS.
THUS...WE COULD ACTUALLY HAVE SOME STRONG STORMS OVER SOUTHEASTERN
MT THIS AFTERNOON AND EARLY EVENING. THAT IDEA IS SUPPORTED BY THE
00 UTC 4 KM WRF-NMM OUTPUT. OF COURSE...THAT BANKS ON SOME HEATING
OF THE BOUNDARY LAYER THAT IS NOT A GIVEN IF CLOUDS ARE TOO THICK.
IF CLOUDS DO NOT HINDER WARMING TOO MUCH...70S F ARE ATTAINABLE IN
SOUTHEASTERN MT. COLD AIR ADVECTION WILL BEGIN SOONER ACROSS SOUTH
CENTRAL MT...MAKING 60S F MORE COMMON THERE. ISOLATED THUNDERSTORM
WORDING IS STILL NEEDED EVEN WHERE IT WILL BE COOLER THOUGH DUE TO
SEASONABLY STEEP MID-LEVEL LAPSE RATES.

TONIGHT...WE HAVE AT LEAST LOW SHOWER CHANCES THIS EVENING FOR THE
ENTIRE AREA...AND LINGERING THUNDERSTORM CHANCES OVER SOUTHEASTERN
MT AS WELL. HOWEVER...A DRYING TREND WILL BE IN PLACE OVERNIGHT IN
MOST AREAS WITH ONLY WEAK LARGE-SCALE FORCING.

THU...COOL AND CYCLONIC LOW-LEVEL FLOW SHOULD YIELD QUITE A BIT IN
THE WAY OF STRATOCUMULUS CLOUD COVER ACROSS MOST OF THE AREA. THAT
WILL DO LITTLE TO HELP TEMPERATURES...WHICH SHOULD ONLY TOP OUT IN
THE 60S F IN THE LOWER ELEVATIONS. THE 00 UTC GUIDANCE ALL SHOWS A
MODEST SHORT WAVE TROUGH DROPPING INTO THE BACK SIDE OF THE LARGER
500-HPA TROUGH AND ACROSS SOUTHEASTERN MT DURING THE MORNING. THAT
SUPPORTS OUR PREVIOUSLY-ADVERTISED LOW SHOWER CHANCES IN THE MILES
CITY AND BAKER AREAS...BUT LATER FORECASTS MAY EVEN NEED A LOW POP
BEYOND 18 UTC FOR PARTS OF SOUTHEASTERN MT IF THE SHORT WAVE SLOWS
UP AT ALL. SCHULTZ

.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...

MODELS CONTINUE TO POINT TO A WARM AND DRY PERIOD FRIDAY THROUGH
SATURDAY AS AN AMPLIFIED RIDGE PREVAILS OVER THE ROCKIES AND HIGH
PLAINS. HOWEVER...ANOTHER TROUGH IS IN POSITION OVER THE PACIFIC
NORTHWEST BY SATURDAY EVENING TO INVADE THE NORTHERN ROCKIES. THIS
LOOKS LIKE A SPLIT FLOW TROUGH. AS SUCH...THE HIGH COUNTRY WILL
SEE THE BEST POPS WHILE LOWER ELEVATIONS SEE PRIMARILY WIND AS THE
TROUGH MOVES THROUGH SATURDAY NIGHT AND SUNDAY. AT THIS
TIME...THE MODEL PROGGS ARE IN PRETTY DECENT AGREEMENT THROUGH THE
WEEKEND. SO...CONFIDENCE IS ABOVE NORMAL IN THIS SOLUTION. STRONG
ZONAL FLOW SUNDAY NIGHT THROUGH MONDAY WILL KEEP THE LOWER
ELEVATIONS DRY AND BREEZY WHILE WEST FACING SLOPES OF THE
SOUTHWEST MOUNTAINS MAY SEE SOME BRIEF PRECIPITATION FROM ANY WEAK
SHORT WAVE IN THE WESTERLY FLOW.

AS WE HEAD TOWARD THE MIDDLE PART OF NEXT WEEK THE MODELS
INDICATE ANOTHER BROAD TROUGH DEVELOPING OVER THE WEST. HOW THIS
EVENTUALLY UNFOLDS HAS A GREAT DEAL OF UNCERTAINTY. THE ECMWF CUTS
OFF THE UPPER LOW AND MOVES IT THROUGH THE GREAT BASIN AND
CLOBBERS OUR FORECAST AREA...MAINLY IN THE MOUNTAINS...WITH WHAT
COULD BE A WINTER STORM. THE GFS ON THE OTHER HAND DIVES THE UPPER
LOW FURTHER SOUTH AND SLOWS IT DOWN KEEPING OUR REGION GENERALLY
DRY. BLENDED THE TWO FOR NOW LEANING A BIT TOWARD A DRIER SCENARIO
AS PREVIOUS TROUGHS UP TO THAT POINT LOOK TO BE SPLIT FLOWS...AND
THAT CAN OFTEN TIMES BECOME A PERSISTENT OCCURRENCE. THAT
SAID...MIDDLE OF NEXT WEEK MAY BE INTERESTING. BT
&&

.AVIATION...

UNSETTLED WEATHER CONDITIONS WILL CONTINUE OVER THE FORECAST AREA
TODAY. AREAS OF LIGHT TO MODERATE SHOWERS WITH EMBEDDED
THUNDESTORMS ARE EXPECTED IN THE EAST...AS WELL AS OVER THE HIGHER
TERRAIN AND NEARBY AREAS IN THE WEST. WESTERLY WINDS ARE EXPECTED
TO INCREASE WITH SUSTAINED SPEEDS 15 TO 25 KTS AFFECTING WESTERN
ROUTES BY 18Z AND SPREADING EAST THROUGH THE AFTERNOON. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 072 045/065 046/076 047/082 053/068 048/071 051/071
    5/T 20/B    00/U    00/U    12/T    10/B    01/B
LVM 058 038/066 038/077 041/081 046/065 042/068 046/068
    7/T 20/B    00/U    00/U    22/T    11/B    12/W
HDN 075 046/067 041/078 047/085 051/072 046/073 050/074
    5/T 21/B    00/U    00/U    12/T    10/B    01/B
MLS 076 048/065 044/075 048/084 054/073 050/075 053/074
    5/T 32/W    00/U    00/U    12/T    10/U    01/B
4BQ 077 047/064 041/075 045/082 053/075 047/074 050/075
    5/T 31/B    00/U    00/U    12/T    20/U    01/U
BHK 080 048/063 038/071 044/079 050/075 047/073 049/074
    4/T 32/W    00/U    00/U    02/T    20/U    01/U
SHR 074 043/063 038/076 044/083 050/070 044/071 048/072
    4/T 21/B    00/U    00/U    12/T    20/U    01/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS




AREA FORECAST DISCUSSION

NWS BILLINGS MT

 936 AM MDT WED SEP 18 2013

.UPDATE...
UPPER LOW CONTINUES TO APPROACH OUR REGION FROM THE WEST. 95KT H3
JET CURRENTLY LIFTING FROM SE ID INTO NW WY IS PROVIDING UPPER
SUPPORT...AND LINE OF SHOWERS WITH EMBEDDED TSTMS HAS FORMED ALONG
SFC FRONT IN SOUTH CENTRAL MT AND IS NEAR A 3HT TO LVM LINE AS OF
1530Z...MOVING SLOWLY EAST. HIGHWAY 212 HAS BEEN CLOSED OVER
BEARTOOTH PASS PER SOME WET SNOW OVER 9KFT OR SO. FISHER CK SNOTEL
AT 9100 FEET IS CURRENTLY 36F.

FORECAST IS ON TRACK AND HAVE MADE NO SIGNIFICANT CHANGES THIS
MORNING. EASTERN PARTS HAVE CLEARED SO HAVE REDUCED SKY COVER AND
POPS TIL 18Z...AND HAVE ALSO RAISED TEMPS A LITTLE PER THE SUN AND
WEST WINDS. MORNING DESTABILIZING SHOULD BE FOLLOWED BY SOME
STRONGER STORMS IN OUR EAST THIS AFTERNOON AS ASCENT INCREASES...
AND THIS INDEED IS WHAT THE LATEST HRRR IS HINTING AT. TSTMS WILL
BE MORE ISOLD WITH GENERALLY SHOWERY/COOLER WEATHER OUT WEST. 12Z
BOISE RAOB SHOWS 500MB OF -20C AND 700MB TEMP OF -5C...CONTINUING
THE TREND OF COLDER MID AND UPPER LEVEL TEMPS FURTHER SOUTH AS THE
TROF PUSHES THROUGH THE NORTHERN ROCKIES...AND THIS IS CONSISTENT
WITH A MORE AMPLIFIED UPPER JET. ALL THAT BEING SAID...SHOWER
ACTIVITY WILL CONTINUE THROUGH THE DAY AND INTO TONIGHT...WITH
SNOW LEVELS LIKELY TO DROP TO AROUND 8KFT. STRONGER DESCENT AND
LOW LEVEL DOWNSLOPE WINDS WILL REDUCE OUR PCPN CHANCES
SIGNIFICANTLY AFTER 00Z. HAVE RAISED WESTERN POPS THROUGH THE
AFTERNOON THOUGH BASED ON ASCENT...POST FRONTAL MOISTURE AND
COOLING ALOFT.

JKL

&&

.SHORT TERM...VALID FOR TDY AND THU...

PASSAGE OF THE LONG-ADVERTISED UPPER-LEVEL TROUGH IS STILL SET FOR
TODAY...BUT SOME UNCERTAINTY REMAINS IN PRECIPITATION COVERAGE. WE
HAVE MUCH MORE CONFIDENCE IN THE ARRIVAL OF COOL TEMPERATURES.

TODAY...FORCING FOR ASCENT SIMULATED BY MODEL 500-300 HPA Q-VECTOR
FIELDS IS BEING MANIFEST AS RAINFALL IN SOUTHEASTERN ID ALREADY AS
OF 09 UTC. WE EXPECT THAT VERTICAL MOTION AND PRECIPITATION TO GET
UP INTO SOUTH CENTRAL MT THIS MORNING...SO LIKELY POPS REMAIN FROM
COOKE CITY AND LIVINGSTON AND ALL THE WAY UP TO HARLOWTON. THAT IS
SUPPORTED BY ENSEMBLE OUTPUT INCLUDING THE 21 UTC SREF. CONFIDENCE
IS LOWER THAT ANYTHING MORE THAN SCATTERED SHOWERS WILL OCCUR EAST
OF THERE IN PLACES LIKE BILLINGS TODAY BECAUSE MODELS ALL SIMULATE
SUBSIDENCE FROM NEAR THE SURFACE TO 500 HPA...WITH DOWNSLOPE WINDS
AIDING THAT PROCESS BY AFTERNOON TOO. THE DOWNSLOPE SIGNATURE WILL
WEAKEN FROM BIG HORN COUNTY AND INTO SOUTHEASTERN MT...SO POPS ARE
HIGHER /IN THE 50 PERCENT RANGE/ THIS AFTERNOON IN THOSE AREAS. IT
LOOKS LIKE STORMS MAY ACTUALLY FIRE FROM BIG HORN COUNTY EAST OVER
INTO SOUTHEASTERN MT AFTER 18 UTC AS HEIGHT FALLS OCCUR ALOFT WITH
A MODERATELY UNSTABLE BOUNDARY LAYER. FORECAST SOUNDINGS IN PLACES
LIKE EKALAKA SHOW MLCAPE UP TO 800 J/KG AND 50 KT MID-LEVEL WINDS.
THUS...WE COULD ACTUALLY HAVE SOME STRONG STORMS OVER SOUTHEASTERN
MT THIS AFTERNOON AND EARLY EVENING. THAT IDEA IS SUPPORTED BY THE
00 UTC 4 KM WRF-NMM OUTPUT. OF COURSE...THAT BANKS ON SOME HEATING
OF THE BOUNDARY LAYER THAT IS NOT A GIVEN IF CLOUDS ARE TOO THICK.
IF CLOUDS DO NOT HINDER WARMING TOO MUCH...70S F ARE ATTAINABLE IN
SOUTHEASTERN MT. COLD AIR ADVECTION WILL BEGIN SOONER ACROSS SOUTH
CENTRAL MT...MAKING 60S F MORE COMMON THERE. ISOLATED THUNDERSTORM
WORDING IS STILL NEEDED EVEN WHERE IT WILL BE COOLER THOUGH DUE TO
SEASONABLY STEEP MID-LEVEL LAPSE RATES.

TONIGHT...WE HAVE AT LEAST LOW SHOWER CHANCES THIS EVENING FOR THE
ENTIRE AREA...AND LINGERING THUNDERSTORM CHANCES OVER SOUTHEASTERN
MT AS WELL. HOWEVER...A DRYING TREND WILL BE IN PLACE OVERNIGHT IN
MOST AREAS WITH ONLY WEAK LARGE-SCALE FORCING.

THU...COOL AND CYCLONIC LOW-LEVEL FLOW SHOULD YIELD QUITE A BIT IN
THE WAY OF STRATOCUMULUS CLOUD COVER ACROSS MOST OF THE AREA. THAT
WILL DO LITTLE TO HELP TEMPERATURES...WHICH SHOULD ONLY TOP OUT IN
THE 60S F IN THE LOWER ELEVATIONS. THE 00 UTC GUIDANCE ALL SHOWS A
MODEST SHORT WAVE TROUGH DROPPING INTO THE BACK SIDE OF THE LARGER
500-HPA TROUGH AND ACROSS SOUTHEASTERN MT DURING THE MORNING. THAT
SUPPORTS OUR PREVIOUSLY-ADVERTISED LOW SHOWER CHANCES IN THE MILES
CITY AND BAKER AREAS...BUT LATER FORECASTS MAY EVEN NEED A LOW POP
BEYOND 18 UTC FOR PARTS OF SOUTHEASTERN MT IF THE SHORT WAVE SLOWS
UP AT ALL. SCHULTZ

.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...

MODELS CONTINUE TO POINT TO A WARM AND DRY PERIOD FRIDAY THROUGH
SATURDAY AS AN AMPLIFIED RIDGE PREVAILS OVER THE ROCKIES AND HIGH
PLAINS. HOWEVER...ANOTHER TROUGH IS IN POSITION OVER THE PACIFIC
NORTHWEST BY SATURDAY EVENING TO INVADE THE NORTHERN ROCKIES. THIS
LOOKS LIKE A SPLIT FLOW TROUGH. AS SUCH...THE HIGH COUNTRY WILL
SEE THE BEST POPS WHILE LOWER ELEVATIONS SEE PRIMARILY WIND AS THE
TROUGH MOVES THROUGH SATURDAY NIGHT AND SUNDAY. AT THIS
TIME...THE MODEL PROGGS ARE IN PRETTY DECENT AGREEMENT THROUGH THE
WEEKEND. SO...CONFIDENCE IS ABOVE NORMAL IN THIS SOLUTION. STRONG
ZONAL FLOW SUNDAY NIGHT THROUGH MONDAY WILL KEEP THE LOWER
ELEVATIONS DRY AND BREEZY WHILE WEST FACING SLOPES OF THE
SOUTHWEST MOUNTAINS MAY SEE SOME BRIEF PRECIPITATION FROM ANY WEAK
SHORT WAVE IN THE WESTERLY FLOW.

AS WE HEAD TOWARD THE MIDDLE PART OF NEXT WEEK THE MODELS
INDICATE ANOTHER BROAD TROUGH DEVELOPING OVER THE WEST. HOW THIS
EVENTUALLY UNFOLDS HAS A GREAT DEAL OF UNCERTAINTY. THE ECMWF CUTS
OFF THE UPPER LOW AND MOVES IT THROUGH THE GREAT BASIN AND
CLOBBERS OUR FORECAST AREA...MAINLY IN THE MOUNTAINS...WITH WHAT
COULD BE A WINTER STORM. THE GFS ON THE OTHER HAND DIVES THE UPPER
LOW FURTHER SOUTH AND SLOWS IT DOWN KEEPING OUR REGION GENERALLY
DRY. BLENDED THE TWO FOR NOW LEANING A BIT TOWARD A DRIER SCENARIO
AS PREVIOUS TROUGHS UP TO THAT POINT LOOK TO BE SPLIT FLOWS...AND
THAT CAN OFTEN TIMES BECOME A PERSISTENT OCCURRENCE. THAT
SAID...MIDDLE OF NEXT WEEK MAY BE INTERESTING. BT
&&

.AVIATION...

UNSETTLED WEATHER CONDITIONS WILL CONTINUE OVER THE FORECAST AREA
TODAY. AREAS OF LIGHT TO MODERATE SHOWERS WITH EMBEDDED
THUNDESTORMS ARE EXPECTED IN THE EAST...AS WELL AS OVER THE HIGHER
TERRAIN AND NEARBY AREAS IN THE WEST. WESTERLY WINDS ARE EXPECTED
TO INCREASE WITH SUSTAINED SPEEDS 15 TO 25 KTS AFFECTING WESTERN
ROUTES BY 18Z AND SPREADING EAST THROUGH THE AFTERNOON. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 068 045/065 046/076 047/082 053/068 048/071 051/071
    5/T 20/B    00/U    00/U    12/T    10/B    01/B
LVM 060 038/066 038/077 041/081 046/065 042/068 046/068
    7/T 20/B    00/U    00/U    22/T    11/B    12/W
HDN 073 046/067 041/078 047/085 051/072 046/073 050/074
    5/T 21/B    00/U    00/U    12/T    10/B    01/B
MLS 075 048/065 044/075 048/084 054/073 050/075 053/074
    5/T 32/W    00/U    00/U    12/T    10/U    01/B
4BQ 077 047/064 041/075 045/082 053/075 047/074 050/075
    5/T 31/B    00/U    00/U    12/T    20/U    01/U
BHK 078 048/063 038/071 044/079 050/075 047/073 049/074
    4/T 32/W    00/U    00/U    02/T    20/U    01/U
SHR 074 043/063 038/076 044/083 050/070 044/071 048/072
    4/T 21/B    00/U    00/U    12/T    20/U    01/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS




AREA FORECAST DISCUSSION

NWS ALBUQUERQUE NM

 256 PM MDT WED SEP 18 2013

.DISCUSSION...
ANOTHER ACTIVE WX SCENARIO SHAPING UP OVER THE REGION FOR REMAINDER
OF TODAY THRU THURSDAY. CIRA LAYERED TOTAL PW PRODUCT SHOWS ABUNDANT
LOW/MID LEVEL MOISTURE ACROSS THE REGION WITH VERY DRY CONDITIONS
ALOFT. VALUES ARE ON THE ORDER OF 130-160 PCT OF NORMAL. A THIN 30-
50 KT UPPER JET AXIS OVER NM AS SEEN ON THE LATEST AMDAR DATA IS
INTERACTING WITH THE LOW LEVEL MOISTURE AND INSTABILITY TO PRODUCE
A WELL DEFINED BAND OF THUNDERSTORMS OVER WESTERN AND NORTHERN NM.
STEERING FLOWS ARE STRONG TODAY HOWEVER THE SHEAR AXIS IS ORIENTED
IN THE DRXN OF STORM MOTION SO MORE LOCALLY HEAVY RAINFALL ON TAP.
LATEST HRRR SHOWS THIS AREA OF SHOWERS AND STORMS PROPAGATING EVER
SO SLOWLY EAST THIS EVENING INTO THE RIO GRANDE VALLEY AND NEARBY
HIGH TERRAIN. HAVE RAISED POPS TO HIGH CHANCE AND LIKELY FOR CENTRAL
NM.

EVEN MORE ACTIVE CONDITIONS WILL TAKE SHAPE INTO THURSDAY NIGHT BUT
MORE INTO THE EASTERN PLAINS. A LARGE UPPER TROUGH OVER THE PACIFIC
NW WILL SLIDE EAST INTO THE GREAT PLAINS AND HELP DRIVE A SURFACE
BACK DOOR FRONTAL BOUNDARY INTO NM. MEANWHILE...A VERY WELL DEFINED
UPPER WAVE EMBEDDED ON THE BACK SIDE OF THE LARGE SCALE WAVE WILL
SLIDE OVER NORTHERN NM AND HELP LIFT FOCUS OVER FRONT. CURRENT QPF
VALUES ARE POTENTIALLY TOO LOW FOR THIS EVENT ACROSS THE EAST WHERE
SUBSTANTIALLY MOISTURE REMAINS IN PLACE. FLOODING IS NOT EXPECTED
HOWEVER SOME LOCALIZED IMPACTS ARE LIKELY IF THE RAIN FALLS OVER
THE WRONG SPOT. ALSO RAISED POPS FOR THE EASTERN PLAINS THURSDAY
NIGHT TO LIKELY. TEMPS THROUGH THIS PERIOD WILL COOL BELOW NORMAL
FOR MUCH OF THE REGION...ESPECIALLY THE EAST.

MODELS DO INDICATE STRONGER WESTERLIES AND DRIER AIR SHIFTING EAST
INTO THE STATE FRIDAY THRU SUNDAY HOWEVER STRONG MOISTURE RECYCLING
PROCESSES WILL STILL BE AT PLAY. LOW CLOUDS AND FOG ARE POSSIBLE
ANY NIGHT ESPECIALLY IF SKIES CLEAR AND WINDS TAPER OFF. TEMPS WILL
BE COOL OUT WEST WHERE MUCH DRIER DEWPOINTS WILL MOVE IN. THE
EXTENDED PATTERN IS STILL HIGHLY UNCERTAIN SO MADE NO CHANGES. THE
ECMWF PROGS A DEEP LARGE SCALE STATIONARY UPPER LOW OVER THE GREAT
BASIN WITH A RELATIVELY ABUNDANT MONSOONAL MOISTURE TAP OVER NM. THE
GFS HAS AN EVEN DEEPER TIGHTLY WOUND COLD UPPER LOW DRIVING EAST
ACROSS THE CENTRAL ROCKIES THRU MID WEEK.

GUYER

&&

.FIRE WEATHER...
SCATTERED WETTING THUNDERSTORMS FOUND ACROSS WESTERN AND NORTHERN
AREAS WILL TRANSITION EASTWARD THIS EVENING BEFORE DIMINISHING SOME.
DRIER AIR WILL EVENTUALLY FILL IN FROM WEST TO EAST LATER TONIGHT
AND WILL SET THE STAGE FOR A DRIER WESTERN AND CENTRAL AREAS ON
THURSDAY.

A BACK DOOR COLD FRONT IS STILL EXPECTED FOR THURSDAY WITH EASTERN
AREAS OBSERVING THAT INFLUENCE. THIS INCLUDES WETTING SHOWERS AND
THUNDERSTORMS WHICH WOULD FAVOR MOST OF THE EASTERN PLAINS THURSDAY
AFTERNOON INTO THE OVERNIGHT. MIXING HEIGHTS WILL INCREASE ACROSS
THE MAJORITY OF THE AREA ALTHOUGH TRANSPORT WINDS WILL COME DOWN
MOST AREAS SO VENTILATION RATES WILL LOWER PRETTY MUCH AREAWIDE.

THE BACK DOOR COLD FRONT WILL PUSH THROUGH THE CENTRAL MOUNTAINS
THURSDAY NIGHT AND MOST LIKELY MAKE IT TO THE AZ STATE LINE BY
FRIDAY MORNING. MIXING DURING FRIDAY AFTERNOON SHOULD SET UP A
CONVERGENCE BOUNDARY NEAR THE CONTINENTAL DIVIDE AND MOST LIKELY
PROVIDE A FOCUS FOR THUNDERSTORMS THERE. THE ATMOSPHERE COULD BE TOO
STABLE FOR SIGNIFICANT SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS
CENTRAL AND EASTERN AREAS DUE TO RESIDUAL IMPACTS FROM THE COLD
FRONT. HUMIDITY VALUES WILL BE UNSEASONABLY HIGH FRIDAY AFTERNOON.
TEMPERATURES WILL BE COOLER THAN NORMAL CENTRAL AND EASTERN AREAS
WHILE BEING NEAR NORMAL WEST OF THE CONTINENTAL DIVIDE. VENTILATION
RATES WILL BE LOWEST EXTENDING FROM ZONE 109 NORTHEASTWARD OVER THE
MIDDLE RIO GRANDE VALLEY AND AREAS TO THE LEE OF THE SANGRE DE
CRISTOS.

THE NEXT PACIFIC TROUGH WILL PLUNGE INTO THE FAR WESTERN US SATURDAY
AND CONTINUE TO TRAVERSE ACROSS THE INTERMOUNTAIN WEST ON SUNDAY.
MOISTURE WILL TRY TO SEEP UP FROM MEXICO AHEAD OF THIS TROUGH SO
LOOK FOR UNSETTLED WEATHER ACROSS THE WEST ON SATURDAY TRANSITIONING
SOME EASTWARD ON SUNDAY. WETTING RAIN WOULD CERTAINLY BE POSSIBLE
ALTHOUGH NOT AS WIDESPREAD AS THE PREVIOUS WEEK. HUMIDITY IS
EXPECTED TO TREND UP ACROSS THE WEST ON SATURDAY WHILE LOWER ACROSS
THE EAST. ON SUNDAY...HUMIDITY IS EXPECTED TO LOWER AREAWIDE
ALTHOUGH THIS COULD CHANGE. VENTILATION WILL INCREASE DURING THE
WEEKEND THANKS TO STRONGER WEST/SOUTHWEST TRANSPORT WIND. CONFIDENCE
IS PRETTY GOOD THAT A PACIFIC TROUGH WILL IMPACT THE AREA BUT STILL
NOT TOTALLY SURE ABOUT HOW MUCH MOISTURE WILL SEEP UP FROM THE SOUTH
AND FEED THE TROUGH. SURFACE WIND SHOULD ALSO INCREASE DURING THE
WEEKEND PERIOD.

ANOTHER PACIFIC TROUGH IS EXPECTED TO AFFECT THE WESTERN US BY THE
MIDDLE OF NEXT WEEK. THE LONG RANGE MODELS DIFFER SOMEWHAT IN THE
EXTENSION SOUTHWARD OF THE TROUGH BUT EITHER WAY IMPACT POTENTIAL
WOULD INCREASE BY MID NEXT WEEK. DEPENDING ON HOW THE TROUGH COMES
IN...ADDITIONAL WETTING RAIN WOULD BE POSSIBLE. CONDITIONS FOLLOWING
THE TROUGH PASSAGE COULD LEAD TO THE MOUNTAINS FIRST BIG FREEZE OF
THE FALL SEASON SO WILL BE WATCHING THAT AS THAT WOULD BEGIN THE
CURING PROCESS TO THE ABUNDANT FUELS THAT HAVE GREENED UP THIS SUMMER.

50

&&

.AVIATION...
18Z TAF CYCLE
SATELLITE...RADAR IMAGERY AND LIGHTNING TRENDS POINT TOWARDS A
POTENT UPPER LEVEL WAVE AND MID LEVEL FRONTAL BAND PASSAGE TODAY.
THE MOST ACTIVE AREA WILL BE FOUND ACROSS THE NORTHWEST HALF
THROUGH THIS AFTERNOON AND THEN TRANSITION EASTWARD DURING THE
EVENING. WENT BULLISH FOR VCSH AND VCTS AND ASSOCIATED CB/S AT
MANY TERMINAL SITES. WENT WITH A TEMPO AT SAF WITH SOME MODERATE
VIS RESTRICTIONS AND GUSTIER WINDS. BUT CANT RULE OUT THAT AT ABQ
AND EVENTUALLY LVS AS THE DAY PROCEEDS. WILL DEFINITELY UPDATE
ONCE A CLEARER PICTURE OF THE STORM EFFECTS COMES INTO VIEW. GUSTY
OUTFLOW WINDS AND PAST MOVING STORMS WITH BRIEF MVFR CONDITIONS
WILL BE THE THREAT OF THE DAY. CANT RULE OUT CONVECTIVE GUSTS TO 50
KT IN THIS ENVIRONMENT ALTHOUGH WENT LIGHTER IN THE TERMINAL
FORECASTS. FOLLOWING THE DISTURBANCE PASSAGE...A BRIEF BREAK COULD
CREATE ADDITIONAL LOW CIGS/VIS RESTRICTIONS ACROSS EASTERN AND
CENTRAL AREAS. THE HIGH MOUNTAIN BASINS ARE SUSCEPTIBLE BUT ALSO
THINKING PORTIONS OF THE EASTERN PLAINS LIKE WHAT WAS OBSERVED
EARLIER THIS MORNING. WILL BE WATCHING ROW CLOSELY TONIGHT.

50

&&

.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON......................  55  80  50  80 /  20   5   5   5
DULCE...........................  48  76  42  76 /  30   5  10   5
CUBA............................  51  79  46  76 /  50  10  10   5
GALLUP..........................  50  78  44  78 /  20   5   5   5
EL MORRO........................  48  74  45  73 /  40  10  10   5
GRANTS..........................  49  76  45  74 /  40   5  10   5
QUEMADO.........................  51  78  48  77 /  40  10  10   5
GLENWOOD........................  54  81  54  82 /  30  10   5  10
CHAMA...........................  47  68  41  68 /  40  10  10  10
LOS ALAMOS......................  55  75  51  70 /  60  10  10   5
PECOS...........................  53  71  49  64 /  50  20  30  10
CERRO/QUESTA....................  51  73  45  70 /  50  20  20   5
RED RIVER.......................  44  64  40  61 /  60  30  30  10
ANGEL FIRE......................  40  68  36  64 /  50  30  30   5
TAOS............................  51  74  44  71 /  50  20  20   5
MORA............................  50  72  45  64 /  40  30  30  10
ESPANOLA........................  55  81  51  76 /  50  10  10   5
SANTA FE........................  55  74  51  70 /  50  10  20  10
SANTA FE AIRPORT................  55  78  53  72 /  50  10  10   5
ALBUQUERQUE FOOTHILLS...........  60  80  57  76 /  50   5  10   5
ALBUQUERQUE HEIGHTS.............  62  82  60  78 /  50   5  10   5
ALBUQUERQUE VALLEY..............  61  83  59  79 /  50   5  10   5
ALBUQUERQUE WEST MESA...........  60  84  58  80 /  50   5  10   5
LOS LUNAS.......................  60  83  58  79 /  50   5  10   5
RIO RANCHO......................  60  84  58  79 /  50   5  10   5
SOCORRO.........................  62  84  61  81 /  50  10  10   5
SANDIA PARK/CEDAR CREST.........  56  79  52  73 /  60  20  20  10
TIJERAS.........................  56  77  53  72 /  60  10  20   5
MORIARTY/ESTANCIA...............  51  75  50  69 /  50  20  30  10
CLINES CORNERS..................  54  74  51  66 /  40  30  50  10
GRAN QUIVIRA....................  55  75  52  70 /  40  20  30  10
CARRIZOZO.......................  57  77  56  73 /  20  10  20  10
RUIDOSO.........................  52  69  53  65 /  30  30  30  30
CAPULIN.........................  56  72  48  66 /  20  40  40   5
RATON...........................  54  76  49  69 /  20  30  40   5
SPRINGER........................  55  78  50  70 /  20  30  40   5
LAS VEGAS.......................  53  74  48  65 /  30  30  40   5
CLAYTON.........................  62  76  54  71 /  20  40  50   5
ROY.............................  58  77  53  68 /  20  40  50   5
CONCHAS.........................  64  82  60  73 /  10  30  50   5
SANTA ROSA......................  62  82  59  72 /  20  30  60  10
TUCUMCARI.......................  66  84  61  76 /  10  30  60   5
CLOVIS..........................  63  80  61  74 /   5  30  60  10
PORTALES........................  62  80  61  74 /   5  30  60  20
FORT SUMNER.....................  64  82  62  76 /  10  20  60  10
ROSWELL.........................  65  83  64  79 /  10  30  40  20
PICACHO.........................  58  78  57  72 /  20  20  30  20
ELK.............................  55  73  54  68 /  40  30  30  40

&&

.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$






AREA FORECAST DISCUSSION

NWS GRAND FORKS ND

 1240 PM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 1224 PM CDT WED SEP 18 2013

FORECAST CHALLENGES THIS UPDATE PERIOD IS MAINLY MAXIMUM
TEMPERATURES AND PCPN CHANCES.

CLEARING JUST STARTING TO WORK INTO FAR SW FA ALONG ND/SD BORDER
AREA AND ALSO SEEING SOME BREAKS TAKING PLACE IN THE CENTRAL
VALLEY. WILL LIKELY CONTINUE TO SEE CLEARING SPREADING NORTHWARD
HOWEVER HOW MUCH WE CAN RECOVER IN MID SEPTEMBER IN QUESTION.
THERMAL RIDGE AXIS OVER FA SO ANY SOLAR SHOULD RESULT IN QUICK
RECOVERY. AM HESITANT TO DROP TEMPERATURES TOO MUCH IN CASE
CLEARING ACCELERATES/EXPANDS SO WILL ONLY MAKE SOME MINOR
ADJUSTMENTS. SMALL CLUSTER OF CONVECTION WHICH AFFECTED A SMALL
PART OF THE CENTRAL/NORTHERN FA CONTINUES TO WEAKEN SO WILL KEEP
FORECAST DRY MOST AREAS. WILL KEEP LOW POPS ACROSS W/NW FA LATE
AFTERNOON IN CASE AREA OF SHOWERS ACROSS N CENTRAL ND CLIP FAR NW
FA AND IF SOMETHING CAN GET GOING ALONG NW/SE ORIENTED BOUNDARY
FROM WEST CENTRAL ND TO SE ND/SD BORDER AREA.

UPDATE ISSUED AT 936 AM CDT WED SEP 18 2013

CHANGES THIS UPDATE PERIOD WERE TO EXTEND/EXPAND LOW POPS ACROSS
CENTRAL PORTIONS OF FA AS CONVECTION HOLDING TOGETHER AS IT
PROPAGATES ENE INTO CENTRAL/NORTHERN FA. ACTUALLY SEEING A FEW LTG
STRIKES SO MENTIONED THUNDER FOR THE REMAINDER OF THE AM. WITH LOW
CIGS FOG HOLDING ON A LITTLE LONGER BUT SHOULD CONTINUE TO
IMPROVE.  WILL ADDRESS CLOUD TRENDS AND TEMPERATURES NEXT UPDATE.

UPDATE ISSUED AT 714 AM CDT WED SEP 18 2013

EXPANDED 20 POPS ACROSS THE FAR WESTERN FORECAST AREA FROM 12 TO
15 UTC THIS MORNING TO ACCOUNT FOR BAND OF LIGHT SHOWERS FROM
HARVEY TO EDGELEY...MOVING TO THE EAST-NORTHEAST AROUND 25 MPH.
HRRR SUGGESTS THIS ACTIVITY SHOULD DISSIPATE AS IT PROPAGATES
EAST. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO CLOUD COVER.
REST OF THE FORECAST IN GOOD SHAPE.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.

LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.

ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.

SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.

THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.

SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1234 PM CDT WED SEP 18 2013

IFR CLOUD DECK HANGING TOUGH OVER THE REGION THIS AFTERNOON...WILL
LIKELY TAKE A FEW MORE HOURS TO LIFT TO MVFR/VFR.  NEXT UP WILL BE A
BATCH OF SHOWERS AND THUNDERSTORMS FOR THIS EVENING AND LATE NIGHT
THAT WILL MOVE EASTWARD OVERNIGHT AS A STRONG COLD FRONT SWEEPS
ACROSS THE DAKOTAS. TIMING AND COVERAGE UNCERTAINTY LINGERS...SO
THIS THREAT HAS BEEN COVERED WITH VCTS FOR THIS 18Z TAF ISSUANCE.
SOUTH-SOUTHEAST WIND AHEAD OF THE FRONT WILL DECREASE WITHIN THE
TROUGH AFTER 00Z...THEN SHIFT TO THE WEST-NORTHWEST AFTER FRONTAL
PASSAGE.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...VOELKER
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...WJB







AREA FORECAST DISCUSSION

NWS GRAND FORKS ND

 942 AM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 936 AM CDT WED SEP 18 2013

CHANGES THIS UPDATE PERIOD WERE TO EXTEND/EXPAND LOW POPS ACROSS
CENTRAL PORTIONS OF FA AS CONVECTION HOLDING TOGETHER AS IT
PROPAGATES ENE INTO CENTRAL/NORTHERN FA. ACTUALLY SEEING A FEW LTG
STRIKES SO MENTIONED THUNDER FOR THE REMAINDER OF THE AM. WITH LOW
CIGS FOG HOLDING ON A LITTLE LONGER BUT SHOULD CONTINUE TO
IMPROVE.  WILL ADDRESS CLOUD TRENDS AND TEMPERATURES NEXT UPDATE.

UPDATE ISSUED AT 714 AM CDT WED SEP 18 2013

EXPANDED 20 POPS ACROSS THE FAR WESTERN FORECAST AREA FROM 12 TO
15 UTC THIS MORNING TO ACCOUNT FOR BAND OF LIGHT SHOWERS FROM
HARVEY TO EDGELEY...MOVING TO THE EAST-NORTHEAST AROUND 25 MPH.
HRRR SUGGESTS THIS ACTIVITY SHOULD DISSIPATE AS IT PROPAGATES
EAST. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO CLOUD COVER.
REST OF THE FORECAST IN GOOD SHAPE.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.

LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.

ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.

SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.

THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.

SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 714 AM CDT WED SEP 18 2013

IFR/MVFR CLOUD DECK WILL BE VERY SLOW TO DISSIPATE TODAY GIVEN
MOIST SOUTHERLY FLOW AND A STRONG MID-LEVEL INVERSION. EXPECT
CEILINGS TO DISSIPATE AND LIFT FROM SOUTHWEST TO NORTHEAST
BEGINNING EARLY-MID AFTERNOON. SHOWERS AND THUNDERSTORMS WILL
DEVELOP LATE THIS AFTERNOON AND EVENING AND MOVE EASTWARD
OVERNIGHT AS A STRONG COLD FRONT SWEEPS ACROSS THE DAKOTAS...
BUT GIVEN TIMING AND COVERAGE UNCERTAINTY...WILL COVER THE THREAT
WITH VCTS FOR 12 UTC TAFS. SOUTH-SOUTHEAST WIND AHEAD OF THE FRONT
WILL SHIFT TO THE WEST-NORTHWEST AFTER FRONTAL PASSAGE WITH GUSTS
UP TO 20 KTS POSSIBLE.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...VOELKER
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...ROGERS







AREA FORECAST DISCUSSION...UPDATED

NWS GRAND FORKS ND

 714 AM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 714 AM CDT WED SEP 18 2013

EXPANDED 20 POPS ACROSS THE FAR WESTERN FORECAST AREA FROM 12 TO
15 UTC THIS MORNING TO ACCOUNT FOR BAND OF LIGHT SHOWERS FROM
HARVEY TO EDGELEY...MOVING TO THE EAST-NORTHEAST AROUND 25 MPH.
HRRR SUGGESTS THIS ACTIVITY SHOULD DISSIPATE AS IT PROPAGATES
EAST. OTHERWISE...MADE SOME MINOR ADJUSTMENTS TO CLOUD COVER.
REST OF THE FORECAST IN GOOD SHAPE.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.

LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.

ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.

SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.

THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.

SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 714 AM CDT WED SEP 18 2013

IFR/MVFR CLOUD DECK WILL BE VERY SLOW TO DISSIPATE TODAY GIVEN
MOIST SOUTHERLY FLOW AND A STRONG MID-LEVEL INVERSION. EXPECT
CEILINGS TO DISSIPATE AND LIFT FROM SOUTHWEST TO NORTHEAST
BEGINNING EARLY-MID AFTERNOON. SHOWERS AND THUNDERSTORMS WILL
DEVELOP LATE THIS AFTERNOON AND EVENING AND MOVE EASTWARD
OVERNIGHT AS A STRONG COLD FRONT SWEEPS ACROSS THE DAKOTAS...
BUT GIVEN TIMING AND COVERAGE UNCERTAINTY...WILL COVER THE THREAT
WITH VCTS FOR 12 UTC TAFS. SOUTH-SOUTHEAST WIND AHEAD OF THE FRONT
WILL SHIFT TO THE WEST-NORTHWEST AFTER FRONTAL PASSAGE WITH GUSTS
UP TO 20 KTS POSSIBLE.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...ROGERS
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...ROGERS







AREA FORECAST DISCUSSION

NWS GRAND FORKS ND

 355 AM CDT WED SEP 18 2013

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES THROUGH THE DAY
AND THEN CONVECTIVE CHANCES AND SEVERE POTENTIAL THIS EVENING
THROUGH THURSDAY. DESPITE DIFFERING QPF AMOUNTS AND LOCATIONS...
GFS/NAM/ECMWF ARE IN GOOD OVERALL AGREEMENT WITH SURFACE LOW TRACK.
THE GEM IS AN OUTLIER AND WILL NOT BE CONSIDERED WITH THIS FORECAST.
FOCUSED ON THE RAP FOR NEAR TERM CLOUD/TEMPERATURE TRENDS.

LOW CLOUDS HAVE ONCE AGAIN ENVELOPED THE ENTIRE FORECAST AREA AND
EXPECT A VERY SLOW EROSION FROM SOUTHWEST TO NORTHEAST THROUGH THE
DAY DUE TO MOIST SOUTH-SOUTHEAST FLOW AND A STRONG MID-LEVEL
INVERSION. RAP 925 HPA RH SUGGESTS THE SUN SHOULD BEGIN TO MAKE AN
APPEARANCE ACROSS SOUTHEAST ND INTO THE DEVILS LAKE BASIN BY EARLY
AFTERNOON...BUT MUCH OF NORTHEAST ND INTO NORTHWEST MN WILL REMAIN
CLOUDY THROUGH THE DAY. WITH INCREASED CLOUD COVER...DROPPED
HIGH TEMPERATURES 3 TO 5 DEGREES. THIS MAY STILL NOT BE ENOUGH
NOTING YESTERDAY/S SLOW RECOVERY. AS A RESULT...SOME AREAS ACROSS
THE NORTH MAY NOT TOP 70 DEGREES. OTHERWISE...HIGHS WILL RANGE
FROM THE LOW 70S ACROSS THE NORTH TO THE LOW 80S ACROSS THE SOUTH.

ADDED SOME SLIGHT CHANCE POPS TO THE DEVILS LAKE BASIN THIS MORNING
TO ACCOUNT FOR WEAKENING ECHOES CURRENTLY ACROSS THE WESTERN HALF
OF ND. OTHERWISE...MOST OF THE DAY SHOULD BE DRY GIVEN A STRONG
CAP AND DELAYED DYNAMIC SUPPORT. REMOVED POPS THROUGH 21 UTC...
INCREASING TO HIGH CHANCES FROM WEST TO EAST THEREAFTER.

SURFACE LOW WILL TRACK ALONG THE ND/SD BORDER WITH A WARM FRONT
EXTENDING TO THE EAST AND INTO WEST CENTRAL MN. CLEARING SKIES
LATE THIS AFTERNOON WILL HELP REALIZE 2000 TO 3000 J/KG OF
INSTABILITY AND WITH PWATS INCREASING TO 1.5 INCHES AND THE
APPROACHING WARM FRONT...EXPECT SCATTERED CONVECTIVE DEVELOPMENT
INITIALLY ACROSS THE SOUTHERN FORECAST AREA. SHOWERS AND
THUNDERSTORMS SHOULD EXPAND NORTHWARD THROUGH THE EVENING WITH THE
APPROACHING COLD FRONT AND STRONG FORCING ALOFT. SPC DAY ONE
CONVECTIVE OUTLOOK HAS EXPANDED ITS SLIGHT RISK TO INCLUDE ALMOST
ALL OF EASTERN ND AND PORTIONS OF NORTHWEST MN. SOME STORMS MAY
BECOME STRONG TO SEVERE WITH THE PRIMARY THREATS BEING LARGE HAIL
AND DAMAGING WIND...BUT CANNOT RULE OUT A TORNADO OR TWO...
ESPECIALLY NEAR FRONTAL BOUNDARIES.

THUNDERSTORMS THAT DEVELOP WILL MOVE EASTWARD AHEAD OF THE ADVANCING
COLD FRONT AND SHOULD EXIT THE FORECAST AREA BY NOON ON THURSDAY.
BREEZY NORTHWEST WIND WILL FOLLOW FRONTAL PASSAGE WITH COOLING
TEMPERATURES. HIGHS THURSDAY WILL RANGE FROM THE LOWER 60S ACROSS
THE NORTHWEST TO THE LOWER 70S ACROSS THE SOUTHEAST.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM CDT WED SEP 18 2013

WITH THE EXCEPTION OF SOME LINGERING WRAP-AROUND SHOWERS ACROSS
THE LAKE OF THE WOODS REGION...FRIDAY WILL BE PARTLY SUNNY AND DRY
AS SURFACE HIGH PRESSURE BUILDS ACROSS THE NATION/S MID-SECTION.
BREEZY NORTHWEST WIND WILL PERSIST AND TEMPERATURES WILL TOP OUT
IN THE LOWER TO MID 60S REGION-WIDE.

SATURDAY-TUESDAY...00Z MODELS APPEAR STABLE RUN TO RUN AND CONFIDENCE
IS SLIGHTLY BETTER THAN AVERAGE. PERIOD BEGINS WITH RIDGING ALOFT...
WITH SOUTHWEST FLOW DEVELOPING BY THE END OF THE WEEKEND. THE
STRONGEST SIGNAL FOR PRECIP APPEARS TO BE MONDAY-MONDAY NIGHT.
SOUTHWEST FLOW ALOFT CONTINUES INTO TUESDAY...ALTHOUGH THERE IS NO
CLEAR SIGNAL FOR PRECIP. TEMPERATURES WILL BEGIN NEAR NORMAL...AND
TRANSITION TO SLIGHTLY ABOVE NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1115 PM CDT TUE SEP 17 2013

THE BAND OF MVFR/IFR CIGS AND SOME FOG/DRIZZLE CONTINUES TO
PERSIST ALONG AND EAST OF THE RED RIVER VALLEY. CONDITIONS SHOULD
FALL INTO THE IFR CATEGORY FOR ALL BUT THE FAR WEST TONIGHT INTO
WED MORNING. GFK COULD BE ON THE EDGE OF THE CLOUD BAND FOR A TIME
TONIGHT...BEFORE CLOUDS ADVECT TO THE WEST WED MORNING. MODELS
WANT TO CLEAR THINGS OUT QUICKLY WED MORNING...BUT THIS IS LIKELY
A BIT TOO QUICK AND SOMETHING WE WILL HAVE TO MONITOR FOR TIMING
PURPOSES. WINDS SHOULD GUST BETWEEN 25-30KT BY WED AFTERNOON IN
ALL AREAS WITH INCREASING CHANCES FOR SHOWERS/STORMS IN THE WEST
AND NORTH AROUND 00Z THU...AND HAVE MENTIONED SOME VCTS FOR
THREAT.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...DK







AREA FORECAST DISCUSSION

NWS BISMARCK ND

 1241 AM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 1232 AM CDT WED SEP 18 2013

CONVECTION MOVING THROUGH WESTERN NORTH DAKOTA HAS POSED A PROBLEM
OVER THE PAST FEW HOURS. SEVERAL WIND MEASUREMENTS FROM 60 MPH TO AS
HIGH AS 83 MPH WERE TAKEN WITHIN 40 MILES OF THE MONTANA-NORTH
DAKOTA BORDER. IT APPEARED THAT SEVERE CRITERIA WIND GUSTS STAYED
JUST ACROSS THE BORDER...THOUGH...AS NO OBSERVATION SITES ON THE
BORDER OR IN NORTH DAKOTA EXCEEDED 40 KNOTS. PRECIPITATION CHANCES
WERE ALTERED OVER THE NEXT 8 HOURS TO ACCOUNT FOR THE LATEST RADAR
TRENDS.

UPDATE ISSUED AT 948 PM CDT TUE SEP 17 2013

A LINE OF NON-SEVERE THUNDERSTORMS HAVE DEVELOPED OVER
SOUTHEASTERN MONTANA COINCIDENT WITH A SHORTWAVE ALOFT AND A
SURFACE BOUNDARY. THE LATEST HRRR IS A LOT MORE BROAD WITH THIS
CONVECTION THAN THE RADAR TRENDS SUGGEST. BASED ON RADAR
OBS/TRENDS...ADDED MORE TEMPORAL AND SPATIAL RESOLUTION TO THE
FORECAST BY INCREASING POPS TO NUMEROUS ACROSS THE SOUTHWEST FOR
THE NEXT FEW HOURS.

THERE IS STILL SOME UNCERTAINTY IF THIS LINE WILL HOLD TOGETHER
AFTER MIDNIGHT OR BREAK UP AS IT MOVES INTO AN AREA OF HIGHER
CONVECTIVE INHIBITION OVER WESTERN NORTH DAKOTA. FOR NOW KEPT
CHANCE POPS WEST AFTER MIDNIGHT AS SHORT-RANGE MODEL GUIDANCE
PAINTS SOME LINGERING CONVECTION OVER THE WESTERN CWA AFTER
MIDNIGHT. THE UPDATED PRODUCTS HAVE BEEN SENT.

UPDATE ISSUED AT 658 PM CDT TUE SEP 17 2013

A STRONG THUNDERSTORM HAS DEVELOPED ALONG A SURFACE BOUNDARY NEAR
THE ND/MT BORDER SOUTH OF SATHER DAM. THIS AREA IS CHARACTERIZED BY
SURFACE-BASED CAPE AROUND 1600 J/KG AND 0-6KM SHEAR AROUND 30
KNOTS. GIVEN THE MARGINAL SEVERE ENVIRONMENT...THINK ANY STORMS
THAT DEVELOP WITHIN THE NEXT HOUR OR TWO SHOULD REMAIN BELOW
SEVERE LIMITS. HOWEVER...WOULD NOT BE SURPRISED TO GET SOME NICKEL
HAIL REPORTS WITH THE STRONGEST CELLS. WILL CONTINUE TO MONITOR
RADAR AND ADJUST THE FORECAST ACCORDINGLY. THE UPDATED PRODUCTS
HAVE BEEN SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 325 PM CDT TUE SEP 17 2013

THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD IS CONVECTIVE
TRENDS/COVERAGE/INTENSITY TONIGHT AND WEDNESDAY. IN THE NEAR
TERM...LOWS CLOUDS HAVE ERODED SLIGHTLY ACROSS THE JAMES RIVER
VALLEY BUT ARE HANGING IN THERE. THERE MAY BE SOME PARTIAL
CLEARING DURING THE EARLY EVENING...BUT STRATUS IS AGAIN EXPECTED
TO FILL BACK IN OVERNIGHT. IN GENERAL...HAVE FAVORED THE SLOWER
MODEL SOLUTIONS FOR POPS TONIGHT...ALTHOUGH I DID ADD A SLIGHT
CHANCE IN THE EXTREME NORTHWEST BEGINNING AT 00Z TONIGHT AS A FEW
SHOWERS HAVE DEVELOPED IN NORTHEAST MONTANA. AM EXPECTING HIGHEST
COVERAGE OF STORMS OVERNIGHT TO BE IN THE NORTHWEST...AND REMAIN
BELOW SEVERE LIMITS. ON WEDNESDAY...A SURFACE LOW AND ASSOCIATED
COLD FRONT WILL PUSH THROUGH THE STATE. STRONG WARM AIR ADVECTION
AHEAD OF THE FRONT WILL PROVIDE SIGNIFICANT WARM AIR ALOFT...WHICH
SHOULD HELP SUPPRESS STORMS OVER MUCH OF THE FORECAST AREA. PER
THE SPC SWODY2 DISCUSSION...THERE IS A CONDITIONAL THREAT OF
SEVERE WEATHER...MAINLY NORTH...IF THE CAP IS BROKEN. THAT THREAT
WOULD ALSO INCLUDE AN ISOLATED TORNADO DUE IN PART TO BACKED SURFACE
FLOW NEAR THE SURFACE LOW. DID NOT CHANGE PREVIOUS FORECAST MUCH
AT ALL IN TERMS OF POPS...WITH CHANCE TO LIKELY ACROSS THE NORTH.
THERE WILL LIKELY BE A RATHER LARGE TEMPERATURE SPREAD FROM
NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA ON
WEDNESDAY...WITH HIGHS IN THE LOWER 70S NORTHWEST TO MID/UPPER 80S
SOUTHEAST.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 325 PM CDT TUE SEP 17 2013

FOCUS IN THE LONG TERM IS ON THE POTENTIAL FOR SEVERE WEATHER
WEDNESDAY NIGHT.

THE 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT ON A SURFACE LOW
ACROSS SOUTHEAST MONTANA WEDNESDAY MORNING PROPAGATING INTO CENTRAL
NORTH DAKOTA BY LATE AFTERNOON. AN ASSOCIATED COLD FRONT IS FORECAST
TO BE NEAR THE HIGHWAY 83 CORRIDOR BY 00 UTC THURSDAY. WIDESPREAD
HIGHS IN THE 80S ARE FORECAST AHEAD OF THE COLD FRONT WITH SURFACE
DEWPOINTS IN THE 60S. DECENT DEEP LAYER BULK SHEAR AND SURFACE BASED
CAPE VALUES OF 1500-2000 J/KG AHEAD OF THE FRONT WITH THE AMPLE
MOISTURE AND DAYTIME HEATING WILL GIVE THE POTENTIAL FOR SUPERCELL
FORMATION. HOWEVER...THE 12 UTC NAM/GFS BUFR SOUNDINGS INDICATE
CAPPING IN THE 850 TO 800 MB LEVEL...WHICH WILL PLACE A LIMIT ON
SURFACE INITIATION IF FRONTAL FORCING CANNOT OVERCOME THIS
INHIBITION. THE BEST CHANCE FOR CONVECTION IS EXPECTED TO BE
WEDNESDAY EVENING AND INTO THE NIGHT NORTH OF HIGHWAY 2. SPC DOES
HAVE A SLIGHT RISK ACROSS THE NORTHWEST AND NORTH CENTRAL WEDNESDAY.
MAIN THREATS WILL BE LARGE HAIL AND DAMAGING WINDS...BUT WITH DECENT
LOW LEVEL SHEAR THE TORNADO THREAT CAN NOT BE RULED OUT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1232 AM CDT WED SEP 18 2013

THUNDERSTORMS ARE FORECAST AT ALL TAF SITES IN THE NEXT 24
HOURS...BUT KBIS/KMOT/KJMS TIMING IS NOT WELL KNOWN AT THIS POINT.
VCTS IS INDICATED AT THOSE SITES. KISN/KDIK HAVE THUNDERSTORMS
ONGOING...SO TIMING IS ESTIMATED IN CURRENT TAF. FRONTAL PASSAGE
TOMORROW WILL RESULT IN WIND SHIFT FROM SOUTHERLY TO
WESTERLY...AND COULD GUST UP TO 30 KNOTS FOR A FEW HOURS AFTER
THE WIND SHIFT.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...SCHECK
SHORT TERM...RK
LONG TERM...MM
AVIATION...SCHECK







AREA FORECAST DISCUSSION

NWS TULSA OK

 1211 PM CDT WED SEP 18 2013

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
ONGOING LIGHT PRECIP MAY FOCUS INTO ISOLATED THUNDERSTORM
COVERAGE ACROSS SE OK/WC AND NW AR THIS AFTERNOON. ANTICIPATED
COVERAGE DOESNT APPEAR SIGNIFICANT ENOUGH TO IMPACT AVIATION
CONCERNS....SO WILL CONTINUE WITH VCTS ACROSS THOSE AREAS FOR THE
FIRST 6 HOURS OR SO. CONVECTIVE INFLUENCES ASIDE ...VFR CONDITIONS
WILL PREVAIL.


&&

.PREV DISCUSSION... /ISSUED 1030 AM CDT WED SEP 18 2013/

DISCUSSION...
FESTERING AREAS OF LIGHT RAIN/SPRINKLES ACROSS THE AREA THIS
MORNING. HOURLY HRRR OUTPUT MAINTAINS CONSISTENCY BY KEEPING THIS
ACTIVITY ONGOING WELL INTO THE AFTERNOON. WILL MAINTAIN THUNDER
CHANCES ACROSS THE EAST THIS AFTERNOON...AND ACROSS THE WEST WILL
CARRY SPRINKLES INTO MID AFTERNOON. PERSISTENT CLOUD COVER WILL
HAMPER AFTERNOON MAX TEMPS...SO HAVE LOWERED ADVERTISED HIGHS
EVERYWHERE. REST OF FORECAST BEYOND FIRST PERIOD LEFT AS IS.

UPDATED ZFP/PFM/AFM OUT SHORTLY.

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&

$$

SHORT TERM...99
LONG TERM....99
AVIATION...23






AREA FORECAST DISCUSSION

NWS TULSA OK

 1030 AM CDT WED SEP 18 2013

.DISCUSSION...
FESTERING AREAS OF LIGHT RAIN/SPRINKLES ACROSS THE AREA THIS
MORNING. HOURLY HRRR OUTPUT MAINTAINS CONSISTENCY BY KEEPING THIS
ACTIVITY ONGOING WELL INTO THE AFTERNOON. WILL MAINTAIN THUNDER
CHANCES ACROSS THE EAST THIS AFTERNOON...AND ACROSS THE WEST WILL
CARRY SPRINKLES INTO MID AFTERNOON. PERSISTENT CLOUD COVER WILL
HAMPER AFTERNOON MAX TEMPS...SO HAVE LOWERED ADVERTISED HIGHS
EVERYWHERE. REST OF FORECAST BEYOND FIRST PERIOD LEFT AS IS.

UPDATED ZFP/PFM/AFM OUT SHORTLY.



&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&

$$

SHORT TERM...23
LONG TERM....21






AREA FORECAST DISCUSSION

NWS SIOUX FALLS SD

 1250 AM CDT WED SEP 18 2013

.UPDATE...
ISSUED AT 924 PM CDT TUE SEP 17 2013

INCREASED THE COVERAGE OF DRIZZLE AND FOG AS STRONG THETA E
ADVECTION AROUND 925MB AND 850MB NOT PROVIDING THE AREA WITH MUCH
IN THE WAY OF SHOWER DEVELOPMENT. LATEST RAP AND NAM SOUNDINGS
SUGGEST A BIT MORE OF A CAP WHEN LIFTING A PARCEL FROM ABOUT 850MB
SO THE THREAT FOR THUNDERSTORMS IS FAIRLY LOW AS WELL...ALTHOUGH
THE GOING 20 TO 30 POPS ALREADY PRETTY LOW. DID PICK UP SOME
MEASURABLE DRIZZLE AT THE AIRPORT. THE BACK EDGE OF THE STRATUS
DOES APPEAR TO FINALLY BE SLOWING AS A DECK AROUND 1500 FEET
LOOKS TO BE DEVELOPING AND STREAMING NORTHWEST. THE VISIBILITIES
HAVE BEEN GRADUALLY IMPROVING SO AT THIS TIME NOT CONCERNED ABOUT
A DENSE FOG ADVISORY. AS ALWAYS ONE AREA TO WATCH WILL BE THE
WESTERN EDGE BETWEEN THE STRATUS AND CLEAR SKIES. THE STRONGEST
LLJ/THETA E ADVECTION WILL END AROUND 6Z SO THE POTENTIAL FOR THE
DRIZZLE TO DECREASE AFTER 6Z AND NOT BE NEARLY AS WIDESPREAD EARLY
WEDNESDAY MORNING.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT TUE SEP 17 2013

THE MAIN FORECAST CHALLENGE TONIGHT IS NOT SO MUCH PRECIPITATION
CHANCES BUT MORE SO WITH CLOUD COVER. CURRENT SATELLITE DEPICTS THE
EDGE OF THE CLEARING JUST WEST OF CHAMBERLAIN AND GREGORY COUNTY.
THE NAM SOUNDINGS AND HUMIDITY TIME SECTIONS ARE TOO BULLISH AT THIS
TIME WITH THE CLEARING SO WERE NOT FOLLOWED FOR THE TONIGHT AND
EARLY WEDNESDAY TIME FRAME. WHAT LOOKED CLOSER WAS THE RAP13 AND
GFS40 SOUNDINGS AND SUBSEQUENT LOW LEVEL HUMIDITY FIELDS. THEY SHOW
A CLEARING TREND MOVING NORTHEASTWARD THROUGH OUR SOUTHWEST ZONES
TONIGHT...WITH CLOUD COVER PINWHEELING BACK TOWARD THE WEST IN OUR
EAST CENTRAL SD ZONES SUCH AS HURON. THIS IS HOW THE CLOUD FORECAST
WAS PLAYED...WITH CLEARING SKIES EDGING TOWARD YANKTON AS THE NIGHT
PROGRESSES...BUT LEAVING HURON CONSIDERABLY CLOUDY. THE MOISTURE
TONIGHT AND EARLY WEDNESDAY DOES BECOME MORE AND MORE SHALLOW. SO BY
WEDNESDAY...IT IS CONCEIVABLE THAT THE CLOUD COVER COULD EXIT OR MIX
OUT IN A BIG HURRY...WITH THE POSSIBLE EXCEPTION OF SOME LINGERING
STRATUS OR STRATOCU IN OUR FAR EASTERN ZONES UNTIL MIDDAY WEDNESDAY.

WITH OR WITHOUT CLOUDS...LOWS WILL BE IMPACTED MORE BY WARM MOIST
ADVECTION TONIGHT AND SOUTHERLY WINDS. THEREFORE MANY LOCATIONS WILL
NOT DROP OFF HARDLY AT ALL FROM THEIR CURRENT TEMPERATURES. AND MANY
LOCATIONS IN OUR EASTERN ZONES MAY EVEN WARM UP A TAD INTO MID
EVENING. TEMPERATURES ON WEDNESDAY STILL LOOK TO BE WELL ABOVE
NORMAL AHEAD OF THE ADVANCING COLD FRONT. CONCERNING RAIN
POTENTIAL...LOOKS TO BE SLIM OR NONE ON WEDNESDAY. BUT LINGERED A
FEW LIGHT SHOWERS ACROSS OUR EASTERN ZONES TONIGHT WHERE THE DEEPEST
LAYER MOISTURE RESIDES. THERE COULD BE SOME PATCHY FOG THROUGHOUT
PARTS OF OUR EASTERN ZONES LATE TONIGHT ALSO.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 354 PM CDT TUE SEP 17 2013

JET ENERGY HANGING BACK QUITE A BIT GOING INTO THE EVENING BACK
THROUGH THE ROCKIES...BUT APPEARS TO MAKE PROGRESS EASTWARD
THROUGH THE NIGHT AS TROUGH NUDGES UP AGAINST PLAINS RIDGE. PROSPECT
FOR CONVECTION FAIRLY MINIMAL WITH STRONGLY CAPPED ATMOSPHERE
AHEAD OF THE BOUNDARY...WHICH REALLY DOES NOT MAKE ITS APPROACH TO
THE CWA UNTIL TOWARD 06Z. MOST...IF NOT ALL...DEEP LAYER FORCING
FOR LIFT IS POST FRONTAL...WITH WITH ELEVATED CAPE ON THE ORDER OF
500-750 J/KG...SO SHOULD BE ABLE TO SCRAPE UP AN INCREASING POTENTIAL
FOR CONVECTION BY LATE NIGHT AND EARLY MORNING FOR POSTFRONTAL AREAS.
FOR ALL THE FAULTS...THE CANADIAN GLOBAL MAY ACTUALLY HAVE THE
CORRECTLY SLANTED VIEW OF THE PRECIP DISTRIBUTION...DEVELOPING
PRECIP A BIT SLOWER...AND A BIT MORE WESTWARD REMOVED FROM LOW
LEVEL FRONTAL POSITION BY VERY LATE WED NIGHT AND THURSDAY.

FOCUS FOR CONVECTION WILL GRADUALLY SHIFT SOUTHEAST WITH THE
PROGRESSION OF DIV Q/FRONTOGENETIC FORCING...WITH MAX FORCING
COMING TOGETHER PERHAPS EARLY MORNING IN THE NORTH/NORTHEAST...
AND AGAIN WITH MAIN JET ENTRANCE DRAGGING ACROSS IN THE AFTERNOON
FOR THE SOUTHEAST. AVERAGE OF A QUARTER TO THIRD INCH IS NOT HARD
TO SUPPORT...EVEN WITH THE DRIER LAYER BELOW CLOUD BASE. TEMPS
WILL BE SOMEWHAT DIFFICULT TO RECOVER MUCH WITH ABUNDANCE OF
CLOUDS... AND UNDERCUTTING COLD AIR ADVECTION DURING THE DAY.
WARMEST MAY SANDWICH THE AREA...BOTH NORTHWEST WHERE WILL GET SOME
SUNSHINE LATER IN THE DAY AND BETTER MIXING...AND THE FAR
SOUTHEAST WHERE SURFACE BOUNDARY WILL LINGER THROUGH THE EARLY
MORNING WITH A FAIRLY MILD START.

FRIDAY INTO SATURDAY WILL FEATURE A COOLER AIRMASS WORKING
SOUTHWARD INTO THE PLAINS...AND WILL BE BREEZY AS WELL WITH MIXING
SUGGESTING DEWPOINTS WELL DOWN INTO THE 30S. THIS WILL OPEN THE
DOOR ON WHAT LOOKS LIKE A CLASSIC RADIATIVE COOLING NIGHT ON
FRIDAY NIGHT...AND SHOULD AT LEAST GET CLOSE TO HAVING SOME UPPER
30S IN COLDER LOCATIONS ALONG/EAST OF INTERSTATE 29. SUPPORT IN
SOME OF THE ENSEMBLE MOS GUIDANCE

RIDGE REBUILDING ACROSS THE PLAINS THIS WEEKEND...AND AS COOL HIGH
SHIFTS EAST WILL GET MODERATING SOUTHERLY WIND FLOW DEVELOPING.
PROBABLY WILL NOT GET FULL IMPACT OF WARMING WINDS YET ON SATURDAY
FOR EASTERN AREAS WITH FAIRLY WEAK FLOW...BUT WEST WILL RESPOND
NICELY RETURNING BACK ABOVE NORMAL. INCREASING WINDS SATURDAY
NIGHT INTO SUNDAY...AS TROUGH IN THE ROCKIES MOVES EAST WITH
PRESSURE FALLS IN LEE ACROSS WESTERN PLAINS. MIXING WILL START TO
BE SOMEWHAT MORE CHALLENGED WITH STABILIZING PROFILES AND SOUTH TO
SOUTHEAST COMPONENT. ANOTHER FAIRLY SHORT WAVELENGTH TROUGH
EXPECTED TO PUSH ACROSS THE NORTHERN PLAINS IN THE SUNDAY NIGHT TO
MONDAY WINDOW...SOME UNCERTAINTY IN TIMING. HOWEVER...SHORT
WAVELENGTH DOES PRODUCE DECENT DYNAMIC FORCING FOR LIFT...AND
WHILE MOISTURE WILL BE SOMEWHAT CHALLENGED TO RETURN...HAVE KEPT
UP WITH GENERALLY MID TO HIGHER CHANCE POPS AS FRONTAL BOUNDARY
PUSHES ACROSS THE AREA. QUICKLY DRYING BEHIND...AND TEMPS
REMAINING MILD FOR TUESDAY WITH MEAN RIDGE BECOMING REESTABLISHED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 1245 AM CDT WED SEP 18 2013

WIDE RANGE OF FLIGHT CATEGORIES OUT THERE TONIGHT...RANGING FROM
LIFR IN PORTIONS OF SOUTHWEST MINNESOTA AND NORTHWEST IOWA TO VFR IN
SOUTH CENTRAL SOUTH DAKOTA. CONTINUES TO BE A TOUGH CALL ON THE
EVOLUTION OF STRATUS AND FOG OVERNIGHT. CLEARING CONTINUES TO MAKE
SOME PROGRESS TO THE NORTHEAST...HOWEVER SIGNS OF NEW STRATUS
DEVELOPING RIGHT BEHIND THE CLEARING. SO THINKING IS MOST AREAS THAT
ARE IN THE STRATUS WILL GENERALLY REMAIN THAT WAY THROUGH THE NIGHT.
TOUGH TO FIGURE OUT WHAT CIGS WILL BE...THUS FEEL THE BEST FORECAST
AT THIS TIME WILL BE TAKING INTO ACCOUNT PERSISTENCE AND ADVECTION.
MODELS SUGGEST THAT THE FAVORED AREA TO SEE A CONTINUED LOWERING OF
THE CIGS AND VISIBILITIES WILL NORTH OF INTERSTATE 90. THUS
CONFIDENCE IS A LITTLE GREATER THAT KHON WILL DROP TO LIFR LATER
TONIGHT. AT KFSD...MOST SITES UPSTREAM ARE IFR...THUS WILL STAY WITH
PERSISTENCE AND NOT DROP TO LIFR IN THIS TAF ISSUANCE. ALTHOUGH IT
IS CERTAINLY POSSIBLE THAT CIGS DO TANK LATER TONIGHT...SO WILL HAVE
TO CONTINUE TO MONITOR. AT KSUX...CLEARING IS NOT TOO FAR AWAY...BUT
NEW STRATUS APPEARS TO BE FORMING. IT IS UNCLEAR AT WHICH HEIGHT
THIS NEW STRATUS WILL SETTLE IN AT. FOR NOW WILL KEEP LOW END
MVFR...BUT AGAIN WILL HAVE TO FOLLOW TRENDS. GIVEN THE SHALLOW
MOISTURE LAYER...WOULD EXPECT TO SEE THE STRATUS DISSIPATE FROM
SOUTHWEST TO NORTHEAST MID TO LATE MORNING. SOME SIGNS THAT IT MAY
EVOLVE INTO STRATOCU FOR THE AFTERNOON HOURS. FOR NOW WILL CARRY A
SCATTERED GROUP AT OUR EASTERN TAF SITES...BUT IT IS POSSIBLE THIS
STRATOCU EXTENDS THE MVFR TIME INTO THE AFTERNOON AT KFSD AND KSUX.
OTHERWISE...IT WILL BE A BREEZY DAY...WITH SOUTHERLY GUSTS UP TO 25
KTS.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

UPDATE...08
SHORT TERM...MJ
LONG TERM...CHAPMAN
AVIATION...CHENARD










AREA FORECAST DISCUSSION

NWS MEMPHIS TN

 647 PM CDT THU SEP 19 2013

.UPDATE...

UPDATED FOR 00Z AVIATION DISCUSSION.

&&

.DISCUSSION...WATER VAPOR SATELLITE/UPPER AIR PROFILER/WSR-88D VAD
WIND PROFILE TRENDS STILL PLACE AN UPPER LEVEL RIDGE AXIS OVER THE
SOUTHEAST UNITED STATES THIS AFTERNOON. THIS IS RESULTING IN
ACROSS THE MID SOUTH WITH ISOLATED TO SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY THUS FAR LIMITED TO PORTIONS OF
CENTRAL/NORTH CENTRAL ARKANSAS AND SOUTH CENTRAL/SOUTHEAST
MISSOURI. TEMPERATURES AS OF 3 PM CDT ARE IN THE MIDDLE TO UPPER
80S AT MOST LOCATIONS. SHOWER AND THUNDERSTORM CHANCES ASSOCIATED
WITH AN APPROACHING COLD FRONT IS THE MAIN FORECAST CHALLENGE IN
THIS AFTERNOON/S FORECAST.

SHORT TERM MODELS INCLUDING THE 3KM HRRR INDICATE SHOWERS AND
THUNDERSTORMS LOCATED OVER PORTIONS OF ARKANSAS AND SOUTHERN
MISSOURI WILL WEAKEN AND DIMINISH WITH THE LOSS OF DAYTIME HEATING
THIS EVENING. THERE IS A POSSIBILITY THAT SOME OF THIS ACTIVITY
MAY REACH AREAS WEST OF THE MISSISSIPPI RIVER THIS EVENING AND
LEFT ISOLATED SHOWERS AND THUNDERSTORMS IN THE FORECAST. HOWEVER...THINK
BETTER SHOWER/THUNDERSTORM CHANCES WILL HOLD OFF UNTIL LATER
TONIGHT AS THE RIDGE MOVES FURTHER EAST AND MID LEVEL HEIGHT FALLS
WEAKEN SLIGHTLY.

A COLD FRONT CURRENTLY LOCATED OVER THE UPPER MIDWEST AND CENTRAL
PLAINS THIS AFTERNOON WILL DROP INTO THE LOWER MISSISSIPPI VALLEY
ON FRIDAY. MODEST MID LEVEL HEIGHT FALLS AND INSTABILITY WILL
ALLOW FOR SHOWERS AND THUNDERSTORMS TO OVERSPREAD THE MID SOUTH
MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER FRIDAY MORNING AND
SPREAD EAST TO THE REMAINDER OF THE FORECAST AREA FRIDAY AFTERNOON
INTO FRIDAY NIGHT.

NOT OVERLY IMPRESSED WITH STRONG/SEVERE THUNDERSTORM POTENTIAL AS
OVERALL SHEAR...INSTABILITY...AND FORCING WILL REMAIN ON THE WEAK
SIDE. LATER SHIFTS WILL MONITOR SHORT TERM TRENDS AND ADD STRONG
THUNDERSTORM MENTION IN THE HAZARDOUS WEATHER OUTLOOK IF
CONDITIONS BECOME MORE FAVORABLE AS THE FRONT APPROACHES. OVERALL
RAINFALL AMOUNTS THROUGH FRIDAY NIGHT MAY AVERAGE AROUND ONE HALF
INCH WITH LOCALIZED AMOUNTS UP TO PERHAPS 1.5-2 INCHES ALONG AND
WEST OF THE MISSISSIPPI RIVER...AND LESSER AMOUNTS TOWARDS THE
TENNESSEE RIVER. THE 12Z GFS HAS REMAINED ON THE QUICKER SIDE OF
MODEL SOLUTIONS TODAY AND LEANED FORECAST TOWARDS THE WRF/ECMWF
WHICH SUGGEST FRONTAL PASSAGE FRIDAY AFTERNOON/FRIDAY NIGHT.

LINGERING SHOWERS AND THUNDERSTORMS MAY PERSIST ON SATURDAY...ESPECIALLY
ACROSS NORTHEAST MISSISSIPPI AS THE FRONT SLOWS BEFORE DEPARTING
THE FORECAST AREA BY SATURDAY NIGHT. COOLER AND DRIER AIR WILL
FILTER IN BEHIND THE FRONT RESULTING IN A PERIOD OF MAINLY RAIN
FREE WEATHER ACROSS THE MID SOUTH THROUGH AT LEAST EARLY NEXT
WEEK AND TEMPERATURES AVERAGING NEAR NORMAL FOR SEPTEMBER. 12Z
GFS/ECMWF INDICATE SOME MODEL RUN TO RUN CONTINUITY ISSUES WITH
THE APPROACH OF AN UPPER LEVEL TROUGH OVER THE
PLAINS/MIDWEST...A BUILDING RIDGE OVER THE LOWER MISSISSIPPI
VALLEY AND THE POTENTIAL FOR WEAK SOUTHERLY LOW LEVEL RETURN FLOW
FROM THE GULF OF MEXICO PRODUCING SHOWERS AND THUNDERSTORMS. WILL
KEEP REMAINDER OF FORECAST NEXT WEEK DRY FOR NOW UNTIL MODELS
COME INTO BETTER AGREEMENT.

CJC

&&
.AVIATION...00Z TAF CYCLE

VFR CONDS WILL PREVAIL THROUGHOUT THE PERIOD. WINDS WILL REMAIN
ABOVE THE 7KT SOUTHERLY THRESHOLD OVERNIGHT AT MEM. ELSEWHERE...WINDS
WILL REMAIN 3-7 KTS PREDOMINANTLY FROM THE SOUTH. TIMING OF
SHOWERS AHEAD OF AN APPROACHING COLD FRONT TOMORROW IS THE BIGGEST
CHALLENGE RIGHT NOW. HAVE DECIDED TO INTRODUCE VCSH AT 14Z AT
MEM...MKL...AND JBR WITH TUP FOLLOWING AROUND 16Z. WIDESPREAD RAIN
AND THUNDERSTORMS SHOULD BECOME PREVAILING BY 18Z AT ALL TAF SITES
AND CONTINUE THROUGH THE END OF THE TAF CYCLE AS THE COLD FRONT
MOVES THROUGH THE REGION.

AC3

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  72  84  67  81 /  30  80  70  40
MKL  68  84  65  78 /  20  60  70  30
JBR  70  80  61  78 /  50  90  60  10
TUP  68  87  68  81 /  10  50  90  70

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

$$








AREA FORECAST DISCUSSION...UPDATED

NWS SPOKANE WA

 1042 PM PDT Tue Sep 17 2013

.SYNOPSIS...
A vigorous upper level disturbance will bring showers and
thunderstorms to north Idaho and the eastern third of Washington
tonight. Rain amounts of a half inch to an inch will be possible
over the Palouse into the Sliver Valley. Rain showers will linger
over the Idaho Panhandle on Wednesday. A drying and warming trend
will occur on Thursday and Friday. A slow moving cold front will
bring increasing chances for rain and cooler weather for the
weekend.


&&

.DISCUSSION...
Two areas of concern this evening. First area stretched from the
southeast corner of WA northeast towards Sandpoint. This area of
rain is mainly stratiform with an occiasonal lightning strike here
or there. Rainfall amounts have ranged from 0.15 to 0.30 with a
localized 0.50 at Corral Creek near the ID/WA/OR border. This band
of rain will keep pushing northeast through the night. The second
area of concern is across northern WA...mainly the Okanogan Valley
and Okanogan Highlands and northeast corner of WA. This has been a
bit more convective in nature. The storms are very slow moving and
radar has indicated rainfall amounts of an inch or more at several
locations. Have issued an Areal Flood Adisory for an area of
heavier rain from Nespelem to Keller to Miles. The precipitation is
very slow moving and the heavy rain could lead to localized
flooding on small creeks and streams as well as along
roadways...like Highway 21. The HRRR models shows this area of
showers slowly shifting east through the night and into Wednesday
morning across northeast WA and north ID. /Nisbet


&&

.AVIATION...
06Z TAFS: Widespread rain continues for most of eastern WA and north
ID. The 06z TAFs may be a bit optimistic with ending time of -shra
for KGEG and KSFF as radar is filling in from the west. If the cloud
cover can hang around through the night and early morning hrs as
well as elevated winds we may be able to aviod stratus/fog across
the eastern TAF locations.


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        50  62  46  75  50  79 / 100  50  10   0   0   0
Coeur d`Alene  49  60  44  73  48  78 / 100  80  10   0   0   0
Pullman        48  63  41  77  46  81 / 100  30  10   0   0   0
Lewiston       53  68  49  83  53  87 / 100  20  10   0   0   0
Colville       50  65  43  75  45  79 / 100  60  20   0   0  10
Sandpoint      50  57  37  71  42  76 / 100 100  20   0   0   0
Kellogg        49  55  44  72  49  78 / 100  90  30  10   0   0
Moses Lake     51  73  46  79  50  80 /  10   0   0   0   0  10
Wenatchee      52  72  51  77  57  78 /  20  10   0   0  10  10
Omak           51  73  47  76  50  77 /  80  10  10   0  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$





AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 229 PM CDT WED SEP 18 2013

.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 229 PM CDT WED SEP 18 2013

MAIN CONCERN THROUGH THE SHORT TERM WILL BE SEVERE THUNDERSTORM
POTENTIAL THURSDAY AFTERNOON INTO THURSDAY EVENING.

WATER VAPOR IMAGERY COUPLED WITH RAP 500MB ANALYSIS SHOWS A WEAK
MID-LEVEL SHORTWAVE TROUGH ROTATING EASTWARD ACROSS CENTRAL WI WITH
INTERIM RIDGING EXTENDING FROM MO/IA INTO MN. VISIBLE
SATELLITE/SURFACE OBSERVATIONS SHOWING A FAIRLY LARGE AREA OF
LINGERING STRATUS ACROSS MN/WI BEHIND THIS DEPARTING WAVE AND IN
ADVANCE OF A SURFACE WARM FRONT EXTENDING FROM SD THROUGH NORTHERN
IA. OTHERWISE...WATER VAPOR DEPICTING A POTENT MID-LEVEL TROUGH WAS ROTATING
EASTWARD THROUGH MT AND THE INTERMOUNTAIN WEST. THIS WILL BE OUR MAIN
WEATHER-MAKER THROUGH THE NEXT 24-36 HOURS...INCLUDING THE POTENTIAL
FOR THURSDAY AFTERNOON/EVENING.

FOR TONIGHT...WILL BE WATCHING A WEAK MID-LEVEL SHORTWAVE TROUGH
MOVE TOWARD THE AREA FROM THE CENTRAL HIGH PLAINS. INCREASING
MOISTURE TRANSPORT INDICATED BY NAM IN THE 925-700MB LAYER NOSES
INTO THE AREA TOWARD MIDNIGHT IN ADVANCE OF THIS WAVE. BUFKIT
SOUNDINGS SHOWING ELEVATED INSTABILITY AT OR ABOVE 8KFT WITH NAM
ALSO INDICATING 1200-1500J/KG IN THE 2-5KM LAYER. NAM QPF FIELD
HOWEVER REMAINS DRY WHILE THE GFS/GEM INDICATE SOME LIGHTER
PRECIPITATION. BASED ON THE FORCING/INSTABILITY SIGNAL...FEEL THERE
IS LEAST A JUSTIFIABLE SLIGHT-LOW END SHOWER/THUNDERSTORM CHANCE.

FOR THURSDAY...POTENT MID-LEVEL TROUGH MOVING ACROSS THE NORTHERN
PLAINS WILL PUSH A SURFACE COLD FRONT INTO THE REGION THURSDAY
AFTERNOON DURING PEAK HEATING. TEMPERATURES TOPPING OFF IN THE UPPER
70S/LOWER 80S AND DEW POINTS IN THE UPPER 60S/AROUND 70 WILL COMBINE
WITH COOLING ALOFT ASSOCIATED WITH THE MID-LEVEL TROUGH TO PRODUCE
0-1KM MLCAPE IN THE 2000-3000J/KG RANGE. THEREFORE...THERE WILL BE
THE POTENTIAL FOR SEVERE THUNDERSTORMS IN THE AFTERNOON/EARLY EVENING HOURS.
ONE MITIGATING FACTOR WILL BE LACK OF GOOD CONVERGENCE RIGHT ALONG
THE FRONT...BUT FEEL MID-LEVEL FORCING WILL MAKE UP FOR THIS.
PRIMARY THREAT WILL BE LARGE HAIL ALONG WITH DAMAGING WINDS AS 0-3KM
BULK SHEAR INCREASES INTO THE 20-30KT RANGE FOR BETTER STORM
ORGANIZATION.  LOOK FOR LINGERING SHOWERS AND THUNDERSTORMS THROUGH
THE EVENING WITH THE BULK OF THIS ACTIVITY SLIDING EAST OF THE AREA
WITH THE FRONT AFTER MIDNIGHT. PLAN ON OVERNIGHT LOWS TO DROP INTO
THE 50S BEHIND THE FRONT.

.LONG TERM...(FRIDAY TROUGH WEDNESDAY)
ISSUED AT 229 PM CDT WED SEP 18 2013

COOLER AIR FILTERS INTO THE REGION FRIDAY ON BREEZY NORTHWEST WINDS.
WITH 850-925MB LAYER TEMPERATURES IN THE 5-11C RANGE FROM NORTH TO
SOUTH...LOOK FOR HIGHS IN THE MIDDLE 60S ACROSS NORTH CENTRAL
WI...TO THE UPPER 60S ELSEWHERE.

LOOKS LIKE COOLER AND QUIET WEATHER THROUGH THE WEEKEND AS HIGH
PRESSURE BECOMES THE DOMINANT WEATHER FEATURE. HIGHS ARE EXPECTED TO
BE IN THE 60S/LOWER 70S SATURDAY AND SUNDAY WITH OVERNIGHT LOWS IN
THE UPPER 30S TO MIDDLE 40S.

FOR MONDAY THROUGH WEDNESDAY...THERE IS A SMALL CHANCE OF SHOWERS
CENTERED AROUND MONDAY NIGHT AS THE SOUTHERN PERIPHERY OF A
MID-LEVEL TROUGH ROTATING THROUGH CANADA BRUSHES THE AREA.
OTHERWISE... GFS AND ECMWF IN GOOD AGREEMENT ON RIDGE BUILDING
THROUGH MIDWEEK FOR A GRADUAL WARMING TREND. RIGHT NOW MODEL
CONSENSUS IS YIELDING HIGHS MAINLY IN THE MIDDLE 70S ON
WEDNESDAY...BUT WOULD NOT BE SURPRISED IF THESE TEMPERATURES
EVENTUALLY GET SHIFTED UPWARD INTO AT LEAST THE UPPER 70S TO LOWER
80S GIVEN THE STRENGTH OF THE UPPER LEVEL RIDGE AND INCREASING
SOUTHERLY SURFACE FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED
AT 1145 AM CDT WED SEP 18 2013

LOW STRATUS DECK MAKING STEADY BUT SLOW PROGRESS NORTHEAST...PER
LATEST SATELLITE TRENDS. NAM12/HRRR MORE AGGRESSIVE IN CLEARING THE
CLOUDS COMPARED TO THE RAP13...BUT THE RAP HAS A BETTER HANDLE ON
WHAT IS OCCURING. SATELLITE TRENDS SUGGEST A 21-22Z CLEARING AT
KRST/KLSE...WHICH LINES UP FAVORABLY WITH THE RAP. WILL STAY WITH
THIS TIMING.

TRICKY FORECAST TONIGHT WITH NUMERICAL GUIDANCE POINTING TO LOW
VSBYS AND POSSIBLY LOW CIGS. SEEMS TIED TO AN INCREASE IN THE LOW
LEVEL MOISTURE RETURN...WITH SOUTHWARD BUILDING STRATUS FROM THE
BACK EDGE OF THE CLOUD LAYER UNDER A LOW LEVEL INVERSION.
PLAUSIBLE...BUT NOT OVERLY CONFIDENT IN THIS RESULT. GOING TO STAY
WITH A MID LEVEL CLOUD DECK FOR NOW...AND SOME MVFR VSBY REDUCTIONS.
THIS WILL HAVE TO BE MONITORED CLOSELY AS THERE IS THE POTENTIAL FOR
LIFR/IFR CIGS/VSBYS.

COLD FRONT WILL SWEEP IN FROM THE WEST THU AFTERNOON. A LINE OF
SHOWERS/STORMS LOOK LIKELY...WITH THE ATMOSPHERE SUPPORTING A STRONG
TO SEVERE THREAT.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...RIECK










AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 1145 AM CDT WED SEP 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 248 AM CDT WED SEP 18 2013

MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON SHOWER CHANCES THIS
MORNING AND TEMPERATURES THIS AFTERNOON.

LATEST WATER VAPOR IMAGERY SHOWED A TWO SHORTWAVES MOVING ACROSS THE
WESTERN GREAT LAKES INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE
FIRST WAVE WAS PUSHING ACROSS EASTERN WISCONSIN/ILLINOIS...WHILE THE
SECOND AS MOVING ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA. A BROAD
TROUGH WAS NOTED OVER THE PACIFIC NORTHWEST INTO THE ROCKIES WITH
SEVERAL EMBEDDED SHORTWAVES NOTED. SURFACE OBSERVATIONS SHOWED
SURFACE LOW PRESSURE DEVELOPING OVER THE WESTERN DAKOTAS...WITH A
WARM FRONT EXTENDING SOUTHEAST ACROSS EASTERN SOUTH DAKOTA THROUGH
WESTERN IOWA INTO CENTRAL MISSOURI.

SHOWERS AND ISOLATED THUNDERSTORMS...WILL PERSIST ACROSS THE AREA
THIS MORNING. THIS ACTIVITY SHOULD THEN GRADUALLY LIFT NORTH LATE
THIS MORNING INTO THIS AFTERNOON AS THE WARM FRONT LIFTS NORTH
ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. THE STRATUS WILL ALSO
LIFT NORTH WITH THE WARM FRONT GIVING WAY TO PARTLY SUNNY SKIES BY
LATE AFTERNOON. THE STRATUS SHOULD START TO BREAK UP BY EARLY
AFTERNOON OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. CLOUDS LOOK
TO HANG ON UNTIL LATE AFTERNOON OVER WESTERN INTO CENTRAL
WISCONSIN. THE CLOUD COVER WILL HAVE A BIG IMPACT ON HIGH
TEMPERATURES TODAY. AREAS THAT SEE CLEARING EARLIER THIS AFTERNOON
WEST OF THE MISSISSIPPI RIVER CAN EXPECT HIGHS IN THE LOWER TO MID
80S. LOCATIONS OVER WESTERN INTO CENTRAL WISCONSIN WILL LIKELY
STRUGGLE TO GET OUT OF THE 70S...WITH EVEN COOLER TEMPERATURES
POSSIBLE OVER NORTH CENTRAL WISCONSIN WHERE THEY COULD BE IN THE
CLOUD COVER THE ENTIRE DAY. DEWPOINTS CLIMB INTO THE MID 60S THIS
AFTERNOON IN THE WAKE OF THE WARM FRONT WITH MLCAPE VALUES
CLIMBING INTO THE 1100 TO 1500 J/KG RANGE RIGHT ALONG AND WEST OF
THE MISSISSIPPI BY LATE AFTERNOON. NOT EXPECTING MUCH IF ANY
SHOWER OR THUNDERSTORM ACTIVITY IN THE WAKE OF THE WARM FRONT AS
WEAK UPPER RIDGING ATTEMPTS TO BUILD INTO THE REGION. 850 MB
MOISTURE TRANSPORT REALLY RAMPS UP LATE TONIGHT INTO EARLY
THURSDAY MORNING AHEAD OF A COLD FRONT AND VIGOROUS UPPER LEVEL
TROUGH APPROACHING FROM THE PLAINS. NOT SEEING MUCH SUPPORT FOR
SHOWERS OR STORMS WITH HEIGHT RISES NOTED OVER THE REGION AT 500
MB EARLY IN THE NIGHT. FLOW ALOFT TURNS SOUTHWEST LATE TONIGHT
INTO EARLY THURSDAY MORNING AS A TROUGH DIGS INTO THE WESTERN
DAKOTAS. WE START TO LOSE THE RIDGING ALOFT LATE TONIGHT SO WOULD
EXPECT SOME SHOWER AND THUNDERSTORM DEVELOPMENT LATE.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 248 AM CDT WED SEP 18 2013

MAIN FORECAST CONCERNS IN THE LONG TERM ARE ON SHOWER AND
THUNDERSTORM CHANCES ON THURSDAY INTO THURSDAY NIGHT...WITH THE
POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS.

A COLD FRONT WILL PUSH INTO WESTERN MINNESOTA EARLY THURSDAY MORNING
AND WILL CONTINUE DRIVING EASTWARD ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY THROUGH THE DAY ON THURSDAY INTO THURSDAY EVENING.
MEANWHILE...AN UPPER TROUGH WILL MOVE EAST OUT OF THE
CENTRAL/NORTHERN PLAINS. A MOIST AND UNSTABLE AIRMASS WILL BE IN
PLACE ACROSS THE FORECAST AREA AS THE FRONT MOVES IN. SHOWERS AND
STORMS ARE EXPECTED AHEAD OF AND ALONG THE FRONT ON THURSDAY. IF THE
STORMS HOLD OFF UNTIL THE AFTERNOON HOURS AND CAN DEVELOP RIGHT
ALONG THE FRONT...THERE WOULD BE THE POTENTIAL FOR A FEW STRONG TO
PERHAPS SEVERE THUNDERSTORMS. DEEP LAYER SHEAR IS LAGGING WELL
BEHIND THE FRONT...WITH THE UPPER JET POSITIONED WELL OFF TO THE
WEST. 0-6 KM BULK SHEAR VALUES ARE RATHER WEAK...IN THE 20 TO 25 KT
RANGE. HOWEVER...THE SHEAR DOES INCREASE BY LATE AFTERNOON AS THE
UPPER TROUGH ATTEMPTS TO CATCH UP TO THE FRONT. 0-6 KM BULK SHEAR
VALUES INCREASE SLIGHTLY TO AROUND 30 KTS BY LATE AFTERNOON...AND
MOST OF THIS SHEAR IS FOCUSED IN THE 0-3 KM LAYER. THINKING THE MAIN
HAZARDS FROM ANY STRONGER STORMS WOULD BE GUSTY WINDS AND POSSIBLY
SOME LARGE HAIL. THIS SHEAR INCREASE LOOKS TO OCCUR OVER WESTERN
INTO CENTRAL WISCONSIN SO THINKING THESE AREAS WOULD HAVE SLIGHTLY
HIGHER POTENTIAL AT SEEING SOME STRONGER STORMS. THE OVERALL SEVERE
THREAT LOOKS LOW AT THIS TIME...UNLESS STORMS HOLD OFF UNTIL LATER
IN THE AFTERNOON. THE FRONT SHIFTS EAST OF THE AREA FRIDAY MORNING
BUT THE UPPER TROUGH MOVES THROUGH DURING THE AFTERNOON HOURS.
LATEST GUIDANCE CONTINUES TO BE A LITTLE SLOWER WITH THE
PRECIPITATION EXITING THE AREA ON FRIDAY SO WE COULD SEE SOME
SHOWERS AND STORMS LINGER OVER CENTRAL AND SOUTHWEST WISCONSIN INTO
EXTREME NORTHEAST IOWA.

CLOUDS SHOULD GRADUALLY DECREASE FROM WEST TO EAST ACROSS THE AREA
FRIDAY AFTERNOON AS THE UPPER TROUGH SWINGS THROUGH AND HIGH
PRESSURE BUILDS IN FRIDAY AFTERNOON INTO FRIDAY NIGHT. HIGH PRESSURE
WILL THEN BE THE DOMINATE WEATHER FEATURE FROM FRIDAY NIGHT THROUGH
THE WEEKEND. A VERY PLEASANT WEEKEND ON TAP FOR THE REGION WITH
HIGHS IN THE 60S ON SATURDAY...THEN WARMING SLIGHTLY INTO THE UPPER
60S TO LOWER 70S ON SUNDAY. THERE IS THE POTENTIAL FOR SOME FROST
THIS WEEKEND OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. LATE
SATURDAY NIGHT INTO EARLY SUNDAY MORNING LOOKS LIKE THE MOST
FAVORABLE TIMEFRAME FOR FROST WHEN TEMPERATURES DROP INTO THE MID
30S. RAIN CHANCES RETURN MONDAY INTO TUESDAY AS ANOTHER TROUGH MOVES
THROUGH THE REGION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1145 AM CDT WED SEP 18 2013

LOW STRATUS DECK MAKING STEADY BUT SLOW PROGRESS NORTHEAST...PER
LATEST SATELLITE TRENDS. NAM12/HRRR MORE AGGRESSIVE IN CLEARING THE
CLOUDS COMPARED TO THE RAP13...BUT THE RAP HAS A BETTER HANDLE ON
WHAT IS OCCURING. SATELLITE TRENDS SUGGEST A 21-22Z CLEARING AT
KRST/KLSE...WHICH LINES UP FAVORABLY WITH THE RAP. WILL STAY WITH
THIS TIMING.

TRICKY FORECAST TONIGHT WITH NUMERICAL GUIDANCE POINTING TO LOW
VSBYS AND POSSIBLY LOW CIGS. SEEMS TIED TO AN INCREASE IN THE LOW
LEVEL MOISTURE RETURN...WITH SOUTHWARD BUILDING STRATUS FROM THE
BACKEDGE OF THE CLOUD LAYER UNDER A LOW LEVEL INVERSION.
PLAUSIBLE...BUT NOT OVERLY CONFIDENT IN THIS RESULT. GOING TO STAY
WITH A MID LEVEL CLOUD DECK FOR NOW...AND SOME MVFR VSBY REDUCTIONS.
THIS WILL HAVE TO BE MONITORED CLOSELY AS THERE IS THE POTENTIAL FOR
LIFR/IFR CIGS/VSBYS.

COLD FRONT WILL SWEEP IN FROM THE WEST THU AFTERNOON. A LINE OF
SHOWERS/STORMS LOOK LIKELY...WITH THE ATMOSPHERE SUPPORTING A STRONG
TO SEVERE THREAT.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04










AREA FORECAST DISCUSSION...UPDATED

NWS MILWAUKEE/SULLIVAN WI

 1133 AM CDT WED SEP 18 2013

.UPDATE...

AREA OF THUNDERSTORMS IN EASTERN IOWA ASSOCIATED WITH 850MB WARM AIR
ADVECTION...LOW LEVEL JET FORCING AND A 500MB SHORTWAVE WILL TRACK
EAST ACROSS NORTHERN IL...WITH THE NORTHERN EDGE OF IT SLIDING
THROUGH SOUTHERN WI. THE HRRR AND OTHER MESOSCALE MODELS SHOW THIS
LITTLE COMPLEX WEAKENING THROUGH EARLY AFTERNOON. WITH HIGH
PRECIPITABLE WATER VALUES AND PERSISTENT WARM AIR ADVECTION OVER
SOUTHERN WI...ANY LITTLE SHORTWAVE COULD KICK UP SOME SCATTERED
SHOWERS ANYWHERE IN WI THIS AFTERNOON. THERE IS UPPER LEVEL
INSTABILITY WITH 800 J/KG OF CAPE TO SUPPORT ISOLATED THUNDER AS
WELL. THE NAM IS SHOWING WEAK SHORTWAVE ENERGY TRACKING THROUGH
CENTRAL/SOUTHERN WI DURING THE AFTERNOON TO WARRANT SLIGHT CHANCE
POPS.

CLOUDS WILL KEEP TEMPS DOWN TODAY...DESPITE 925MB TEMPS WARMING TO
22C WHICH WOULD SUGGEST HIGHS IN THE LOWER 80S. THE GOING FCST
ALREADY ACCOUNTS FOR THE CLOUDS WITH HIGHS IN THE MID/UPPER 70S OVER
MUCH OF THE AREA...SO NO CHANGES EXPECTED.

&&

.AVIATION/18Z TAFS/...

MVFR CIGS IN FAR WESTERN WI WITH DEEPER MOISTURE WILL GRADUALLY
SPREAD EAST INTO SOUTH CENTRAL WI EARLY THIS AFTERNOON. EXPECTING
DAYTIME LOW LEVEL MIXING TO PREVENT IT FROM GETTING AS FAR EAST INTO
MSN BUT THERE IS A SMALL CHANCE AND WILL CONTINUE TO MONITOR. NOT
EXPECTING IT TO MAKE IT TO THE EASTERN TAF SITES.

INCREASING THREAT FOR LIGHT FOG AS DEEPER RH SPREADS IN TNGT.  WL
LEARN TOWARD CIGS REMAINING VFR FOR TNGT BUT ADD SOME LGT FOG.
PERIOD OF LOW LEVEL WIND SHEAR EXPCD TNGT AS LOW LEVEL JET
STRENGTHENS OVER THE REGION.

&&

.PREV DISCUSSION... /ISSUED 329 AM CDT WED SEP 18 2013/

TODAY AND TONIGHT...FORECAST CONFIDENCE...LOW TO MEDIUM

MULTIPLE FORCING MECHANISMS WILL CONTINUE TO TRIGGER SCATTERED
SHOWERS AND A FEW THUNDERSTORMS THIS MRNG. -SHRA FROM INITIAL SHORT
WAVE HAVE PUSHED EAST OF THE AREA. CURRENT -SHRA AND ISOLD T OVER
CWA BEING CAUSED BY FIRST SURGE OF THETA-E ADVECTION AS DEEPER
COLUMN MOISTURE AND WARM AIR SPREADS EASTWARD. FARTHER UPSTREAM...
STRONGER PUSH OF WARM AIR ADVECTION TRIGGERING SCT T OVER CENTRAL
IA. NOSE OF LOW LEVEL JET TRIGGERING THIS ACTIVITY SPREADS NORTHEAST
AND IS EXPECTED TO WEAKEN THIS MRNG. GREATER POTENTIAL FOR SCT SHRA
AND T TO AFFECT WESTERN CWA AFT 12Z. HOWEVER NEED TO KEEP CHANCE
CONTINUING IN EAST DUE TO WEAKER LIFT. DEEPER MOISTURE SPREADING
INTO SRN WI WL ALSO RESULT IN M/CLDY TO CLDY SKIES FOR A GOOD PART
OF THE DAY. CLDS MAY LINGER INTO TNGT BEFORE WARM FRONT PASSES BY
ALLOWING PARTIAL CLEARING AND PATCHY LIGHT FOG.

MAIN LIFT SPREADS EAST AND NORTH OF THE AREA LATER TODAY SO WL
CONTINUE WITH LOW/NO POPS LATER TODAY AND THIS EVENING.  HOWEVER
WEAK LAYER Q-VECTOR CONVERGENCE LINGERS ACROSS SRN WI THRU TNGT.
WITH DEEP MOISTURE AND ELEVATED INSTABILITY IN PLACE AND INCREASING
LOW LEVEL JET AIMED AT SRN WI...NEED TO INCLUDE LOW POPS FOR T LATER
TNGT.

THURSDAY AND FRIDAY...FORECAST CONFIDENCE...MEDIUM

INSTABILITY IS EXPECTED TO INCREASE THURSDAY AS A WARM AND MOIST
AIRMASS IS PULLED INTO THE AREA AHEAD OF AN APPROACHING COLD FRONT.
NOT A REAL OBVIOUS TRIGGER FOR SHOWERS/STORMS DURING THE DAY...BUT
CONTINUED WEAK WARM ADVECTION ALONG WITH A VERY WEAK SHORTWAVE MAY
BE ENOUGH FOR AT LEAST SCATTERED CONVECTION. KEPT MAINLY CHANCE POPS
DURING THE DAY...INCREASING TO LIKELY FROM MADISON WESTWARD BY LATE
AFTERNOON AS THE FRONT DRAWS CLOSER. WENT LIKELY ACROSS THE FORECAST
AREA IN THE EVENING/OVERNIGHT AS THE FRONT MOVES INTO SOUTHERN
WISCONSIN. SOME STORMS COULD BE STRONG TO SEVERE LATE AFTERNOON INTO
THE EVENING GIVEN CAPE VALUES UP TO AROUND 2000 J/KG AND 0-6 KM BULK
SHEAR OF 20-30 KT. THE NEW SPC DAY 2 CONVECTIVE OUTLOOK HAS MOST OF
THE FORECAST AREA IN A SLIGHT RISK FOR SEVERE STORMS.

WITH SOME SUNSHINE EXPECTED THURSDAY...MAINTAINED HIGHS IN THE MID
80S. COULD BE A BIT LOWER IF MORE CLOUDS/PRECIP DURING THE DAY THAN
EXPECTED. ON THE FLIP SIDE...MODELS HAVE 925 MB TEMPS OF 23-25C...SO
UPPER 80S NOT OUT OF THE QUESTION IN SOME SPOTS GIVEN ENOUGH
SUNSHINE.

MODELS ARE STILL DIFFERING A BIT WITH THE TIMING OF THE COLD FRONT
AND MAIN SHORTWAVE FRIDAY. OVERALL THOUGH...SEEMS THAT MODELS ARE
TRENDING SLOWER...SIMILAR TO WHAT THE ECMWF HAS BEEN SUGGESTING FOR
THE LAST COUPLE RUNS. HAVE KEPT SOME HIGHER POPS THROUGH THE
MORNING...BUMPING UP AFTERNOON POPS A BIT. WILL LIKELY NEED TO
INCREASE POPS MORE IF THIS SLOWER TREND CONTINUES IN FUTURE MODEL
RUNS. COOLER TEMPS ARE LIKELY FRIDAY...THOUGH HIGHS ARE STILL
EXPECTED TO BE NEAR NORMAL VALUES.

SATURDAY THROUGH TUESDAY...FORECAST CONFIDENCE...MEDIUM

AFTER A FAIRLY ACTIVE PERIOD...HIGH PRESSURE IS EXPECTED TO SETTLE
IN FOR THE WEEKEND...HANGING ON INTO EARLY NEXT WEEK. SHOULD THUS
SEE A GOOD AMOUNT OF SUNSHINE SATURDAY THROUGH MONDAY WITH NEAR
NORMAL TEMPERATURES.

THE ECMWF IS MAINTAINING A STRONGER SHORTWAVE THAN THE GFS AND
CANADIAN MONDAY NIGHT INTO TUESDAY...THUS KEPT SOME LOW POPS
GOING.

AVIATION/12Z TAFS/...CIGS CONTINUE TO SLOWLY FALL AS DEEPER
MOISTURE SLOWLY SPREADS INTO SOUTHERN WI. EXPECT MVFR CIGS TO SPREAD
INTO KMSN EARLY THIS MRNG. CONFIDENCE LOWER ON MVFR CIGS REACHING
ERN TAF SITES BUT WL CARRY AT LEAST SOME TEMPO GROUPS LATER THIS
MRNG. DAYTIME MIXING MAY PREVENT A LONGER PERIOD OF LOWER CIGS IN
ERN SITES. INCREASING THREAT FOR LIGHT FOG AS DEEPER RH SPREADS IN
AS WELL TNGT.  WL LEARN TOWARD CIGS REMAINING VFR FOR TNGT BUT ADD
SOME LGT FOG. PERIOD OF LOW LEVEL WIND SHEAR EXPCD TNGT AS LOW LEVEL
JET STRENGTHENS OVER THE REGION.

MARINE...TIGHTENING PRESSURE GRADIENT TODAY IN RESPONSE TO LOW
PRESSURE MOVING INTO THE NORTHERN PLAINS WILL CONTINUE TO BRING
GUSTY SOUTH TO SOUTHEAST WINDS...WITH A PROLONGED PERIOD OF 10 TO 20
KNOT WINDS.  FEW WIND GUSTS LIKELY 22-25 KNOTS. BETTER CHANCE FOR
HIGHER WINDS AND RESULTANT WAVES NORTH OF PORT WASHINGTON DUE TO
SHORE ORIENTATION. EXPECTING WAVES TO BUILD TO OVER 4 FEET AT
TIMES.  HENCE WL POST SMALL CRAFT ADVY FOR THIS AREA INTO THURSDAY
EVENING.  AREAS FARTHER SOUTH WL NEED TO BE WATCHED CLOSELY BUT NOT
ENOUGH CONFIDENCE IN A PROLONGED PERIOD OF HIGHER WINDS AND WAVES AT
THIS TIME.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THURSDAY FOR LMZ643.

&&

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...MBK
THURSDAY THROUGH TUESDAY...DDV







AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 608 AM CDT WED SEP 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 248 AM CDT WED SEP 18 2013

MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON SHOWER CHANCES THIS
MORNING AND TEMPERATURES THIS AFTERNOON.

LATEST WATER VAPOR IMAGERY SHOWED A TWO SHORTWAVES MOVING ACROSS THE
WESTERN GREAT LAKES INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE
FIRST WAVE WAS PUSHING ACROSS EASTERN WISCONSIN/ILLINOIS...WHILE THE
SECOND AS MOVING ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA. A BROAD
TROUGH WAS NOTED OVER THE PACIFIC NORTHWEST INTO THE ROCKIES WITH
SEVERAL EMBEDDED SHORTWAVES NOTED. SURFACE OBSERVATIONS SHOWED SURFACE
LOW PRESSURE DEVELOPING OVER THE WESTERN DAKOTAS...WITH A WARM FRONT
EXTENDING SOUTHEAST ACROSS EASTERN SOUTH DAKOTA THROUGH WESTERN IOWA
INTO CENTRAL MISSOURI.

SHOWERS AND ISOLATED THUNDERSTORMS...WILL PERSIST ACROSS THE AREA
THIS MORNING. THIS ACTIVITY SHOULD THEN GRADUALLY LIFT NORTH LATE
THIS MORNING INTO THIS AFTERNOON AS THE WARM FRONT LIFTS NORTH
ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. THE STRATUS WILL ALSO
LIFT NORTH WITH THE WARM FRONT GIVING WAY TO PARTLY SUNNY SKIES BY
LATE AFTERNOON. THE STRATUS SHOULD START TO BREAK UP BY EARLY
AFTERNOON OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. CLOUDS LOOK
TO HANG ON UNTIL LATE AFTERNOON OVER WESTERN INTO CENTRAL
WISCONSIN. THE CLOUD COVER WILL HAVE A BIG IMPACT ON HIGH
TEMPERATURES TODAY. AREAS THAT SEE CLEARING EARLIER THIS AFTERNOON
WEST OF THE MISSISSIPPI RIVER CAN EXPECT HIGHS IN THE LOWER TO MID
80S. LOCATIONS OVER WESTERN INTO CENTRAL WISCONSIN WILL LIKELY
STRUGGLE TO GET OUT OF THE 70S...WITH EVEN COOLER TEMPERATURES
POSSIBLE OVER NORTH CENTRAL WISCONSIN WHERE THEY COULD BE IN THE
CLOUD COVER THE ENTIRE DAY. DEWPOINTS CLIMB INTO THE MID 60S THIS
AFTERNOON IN THE WAKE OF THE WARM FRONT WITH MLCAPE VALUES
CLIMBING INTO THE 1100 TO 1500 J/KG RANGE RIGHT ALONG AND WEST OF
THE MISSISSIPPI BY LATE AFTERNOON. NOT EXPECTING MUCH IF ANY
SHOWER OR THUNDERSTORM ACTIVITY IN THE WAKE OF THE WARM FRONT AS
WEAK UPPER RIDGING ATTEMPTS TO BUILD INTO THE REGION. 850 MB
MOISTURE TRANSPORT REALLY RAMPS UP LATE TONIGHT INTO EARLY
THURSDAY MORNING AHEAD OF A COLD FRONT AND VIGOROUS UPPER LEVEL
TROUGH APPROACHING FROM THE PLAINS. NOT SEEING MUCH SUPPORT FOR
SHOWERS OR STORMS WITH HEIGHT RISES NOTED OVER THE REGION AT 500
MB EARLY IN THE NIGHT. FLOW ALOFT TURNS SOUTHWEST LATE TONIGHT
INTO EARLY THURSDAY MORNING AS A TROUGH DIGS INTO THE WESTERN
DAKOTAS. WE START TO LOSE THE RIDGING ALOFT LATE TONIGHT SO WOULD
EXPECT SOME SHOWER AND THUNDERSTORM DEVELOPMENT LATE.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 248 AM CDT WED SEP 18 2013

MAIN FORECAST CONCERNS IN THE LONG TERM ARE ON SHOWER AND
THUNDERSTORM CHANCES ON THURSDAY INTO THURSDAY NIGHT...WITH THE
POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS.

A COLD FRONT WILL PUSH INTO WESTERN MINNESOTA EARLY THURSDAY MORNING
AND WILL CONTINUE DRIVING EASTWARD ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY THROUGH THE DAY ON THURSDAY INTO THURSDAY EVENING.
MEANWHILE...AN UPPER TROUGH WILL MOVE EAST OUT OF THE
CENTRAL/NORTHERN PLAINS. A MOIST AND UNSTABLE AIRMASS WILL BE IN
PLACE ACROSS THE FORECAST AREA AS THE FRONT MOVES IN. SHOWERS AND
STORMS ARE EXPECTED AHEAD OF AND ALONG THE FRONT ON THURSDAY. IF THE
STORMS HOLD OFF UNTIL THE AFTERNOON HOURS AND CAN DEVELOP RIGHT
ALONG THE FRONT...THERE WOULD BE THE POTENTIAL FOR A FEW STRONG TO
PERHAPS SEVERE THUNDERSTORMS. DEEP LAYER SHEAR IS LAGGING WELL
BEHIND THE FRONT...WITH THE UPPER JET POSITIONED WELL OFF TO THE
WEST. 0-6 KM BULK SHEAR VALUES ARE RATHER WEAK...IN THE 20 TO 25 KT
RANGE. HOWEVER...THE SHEAR DOES INCREASE BY LATE AFTERNOON AS THE
UPPER TROUGH ATTEMPTS TO CATCH UP TO THE FRONT. 0-6 KM BULK SHEAR
VALUES INCREASE SLIGHTLY TO AROUND 30 KTS BY LATE AFTERNOON...AND
MOST OF THIS SHEAR IS FOCUSED IN THE 0-3 KM LAYER. THINKING THE MAIN
HAZARDS FROM ANY STRONGER STORMS WOULD BE GUSTY WINDS AND POSSIBLY
SOME LARGE HAIL. THIS SHEAR INCREASE LOOKS TO OCCUR OVER WESTERN
INTO CENTRAL WISCONSIN SO THINKING THESE AREAS WOULD HAVE SLIGHTLY
HIGHER POTENTIAL AT SEEING SOME STRONGER STORMS. THE OVERALL SEVERE
THREAT LOOKS LOW AT THIS TIME...UNLESS STORMS HOLD OFF UNTIL LATER
IN THE AFTERNOON. THE FRONT SHIFTS EAST OF THE AREA FRIDAY MORNING
BUT THE UPPER TROUGH MOVES THROUGH DURING THE AFTERNOON HOURS.
LATEST GUIDANCE CONTINUES TO BE A LITTLE SLOWER WITH THE
PRECIPITATION EXITING THE AREA ON FRIDAY SO WE COULD SEE SOME
SHOWERS AND STORMS LINGER OVER CENTRAL AND SOUTHWEST WISCONSIN INTO
EXTREME NORTHEAST IOWA.

CLOUDS SHOULD GRADUALLY DECREASE FROM WEST TO EAST ACROSS THE AREA
FRIDAY AFTERNOON AS THE UPPER TROUGH SWINGS THROUGH AND HIGH
PRESSURE BUILDS IN FRIDAY AFTERNOON INTO FRIDAY NIGHT. HIGH PRESSURE
WILL THEN BE THE DOMINATE WEATHER FEATURE FROM FRIDAY NIGHT THROUGH
THE WEEKEND. A VERY PLEASANT WEEKEND ON TAP FOR THE REGION WITH
HIGHS IN THE 60S ON SATURDAY...THEN WARMING SLIGHTLY INTO THE UPPER
60S TO LOWER 70S ON SUNDAY. THERE IS THE POTENTIAL FOR SOME FROST
THIS WEEKEND OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. LATE
SATURDAY NIGHT INTO EARLY SUNDAY MORNING LOOKS LIKE THE MOST
FAVORABLE TIMEFRAME FOR FROST WHEN TEMPERATURES DROP INTO THE MID
30S. RAIN CHANCES RETURN MONDAY INTO TUESDAY AS ANOTHER TROUGH MOVES
THROUGH THE REGION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 608 AM CDT WED SEP 18 2013

LINE OF THUNDERSTORMS IS MOVING NORTHEAST OUT OF NORTH CENTRAL
IOWA AND IS FILLING IN/EXPANDING TO THE NORTH ACROSS SOUTHERN
MINNESOTA. AT THIS TIME...REGIONAL RADARS SHOWING THIS TO BE THE
LAST OF THE CONVECTIVE ACTIVITY TO MOVE THROUGH THIS MORNING AND
THIS IS ALSO THE TREND SHOWN IN THE 18.09Z HRRR. BASED THE PRESENT
MOVEMENT OF THIS LINE...WILL SHOW A 2 HOUR WINDOW OF TSRA AT KRST
RIGHT FROM THE START OF THE TAF AND THEN AROUND 14Z AT KLSE. AFTER
THAT THE PROBLEM BECOMES HOW LONG THE IFR CONDITIONS WILL STICK
AROUND. LOOKING AT THE 18.09Z RAP BUFKIT SOUNDINGS...NOT EXPECTING
THESE TO BEGIN LIFTING UNTIL LATE MORNING WITH KRST NOT BECOMING
MVFR UNTIL EARLY AFTERNOON. DRIER AIR SHOULD THEN START MIXING IN
TO ACTUALLY ALLOW BOTH SITES TO SCATTER OUT BY MID TO LATE
AFTERNOON. DESPITE THE RECENT RAINS...SHOULD BE ENOUGH WIND
OVERNIGHT TO PREVENT FOG FROM FORMING. A COLD FRONT WILL START TO
APPROACH FROM THE WEST OVERNIGHT. SOME ADDITIONAL SCATTERED
CONVECTION COULD DEVELOP LATE TONIGHT OUT AHEAD OF THE FRONT BUT
CONFIDENCE ON THIS IS TOO LOW TO INCLUDE IN THE FORECAST AT THIS
TIME.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04







AREA FORECAST DISCUSSION

NWS LA CROSSE WI

 1133 PM CDT TUE SEP 17 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 315 PM CDT TUE SEP 17 2013

THE MAIN FOCUS IS ON PRECIPITATION CHANCES TONIGHT AND HOW LONG
THEY WILL HOLD ON INTO WEDNESDAY.

LIGHT RAIN SHOWERS CONTINUE TO TRACK TO THE NORTHEAST ACROSS THE
AREA ALONG A SHARP MID LEVEL TROUGH AND WEAKENING MCV. RAINFALL
AMOUNTS HAVE BEEN LIGHT WITH THIS FEATURE AT LESS THAN A TENTH OF
AN INCH AND GUIDANCE HAS NOT DONE A VERY GOOD JOB OF PICKING UP ON
IT. THE EXCEPTION IS THE HRRR WHICH HAS HELD IT TOGETHER THROUGH
MUCH OF TODAY AND CONTINUES TO TAKE IT NORTHEAST INTO NORTH
CENTRAL WISCONSIN THIS EVENING.

WITH BROAD MID LEVEL TROUGHING REMAINING IN PLACE ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY TONIGHT AND LOW LEVEL MOISTURE TRANSPORT
INCREASING OUT OF THE CENTRAL PLAINS...EXPECT THAT SHOWERS AND A
SOME THUNDERSTORMS WILL DEVELOP AND INCREASE IN COVERAGE THROUGH THE
NIGHT. GUIDANCE HAS BEEN FAIRLY CONSISTENT WITH THE NOSE OF THIS
TRANSPORT BEING FOCUSED ACROSS SOUTHEAST MINNESOTA AND NORTHEAST
IOWA...WHICH IS ALSO WHERE THE HIGHEST INSTABILITY DEVELOPS AS
WELL. WIND SHEAR REMAINS LOW OVERNIGHT WITH INSTABILITY ALSO
STAYING ON THE LOW SIDE AND PEAKING AT ABOUT 500-1000J/KG IN
MN/IA. THUS...AM NOT EXPECTING ANY ORGANIZED CONVECTION TO OCCUR.

AS THE TROUGH SHIFTS EAST WITH UPPER LEVEL RIDGING COMING IN TOMORROW
MORNING AND THE MOISTURE TRANSPORT WEAKENS...EXPECT THAT THE
CONVECTION WILL EITHER SHIFT EAST OR DIMINISH IN COVERAGE ALLOWING
FOR A PRECIPITATION FREE DAY. IT WILL BE MUCH MORE HUMID WITH
SURFACE DEW POINTS CLIMBING INTO THE MID TO UPPER 60S. HIGH
TEMPERATURES WILL DEPEND GREATLY UPON CLOUD COVER AS THE STRATUS
IS EXPECTED TO LINGER FOR MUCH OF THE DAY. IF IT CLEARS EARLIER
THAN FORECAST...THEN TEMPS COULD BE ABOUT 4-8F HIGHER.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 315 PM CDT TUE SEP 17 2013

WITH UPPER LEVEL RIDGING IN PLACE WEDNESDAY NIGHT...HAVE GONE DRY
FOR MUCH OF THE REGION DESPITE SOME LOW LEVEL MOISTURE TRANSPORT
DEVELOPING AGAIN. THE MAIN FOCUS FOR PRECIPITATION WILL BE ALONG
THE COLD FRONT AS IT TRACKS TO THE EAST ON THURSDAY OUT AHEAD OF A
CLOSED MID LEVEL LOW. THE 17.12Z NAM CONTINUES TO BE THE FASTEST
OF THE MODEL SOLUTIONS FOR THIS FRONTAL PASSAGE AND HAS IT INTO
CENTRAL WISCONSIN BY 00Z FRIDAY WHILE THE 17.12Z GFS/ECMWF HOLD IT
BACK WEST OF THE MISSISSIPPI RIVER AT THAT SAME POINT. THE TIMING
OF THIS COLD FRONT PASSAGE WILL BE THE MAIN FACTOR WITH WHERE ANY
POTENTIAL SEVERE WEATHER COULD OCCUR. WHILE DEEP SHEAR LOOKS
WEAK...MODIFIED 17.12Z NAM/GFS SOUNDINGS WITH SURFACE DEW POINTS
IN THE UPPER 60S...RATHER THAN LOW/MID 70S...SHOW ABOUT
2000-3000J/KG OF MIXED LAYER CAPE DEVELOPING AHEAD OF THE FRONT.
IF THERE IS ANY SHEAR...ITS IN THE LOWEST 2-3KM AT ABOUT 20-30KTS
WHICH COULD HELP WITH POTENTIALLY ORGANIZING SOME OF THE
CONVECTION INTO BOWING SEGMENTS BRIEFLY.

AS THE FRONT MOVES THROUGH...PRECIPITATION IS EXPECTED TO END
OVERNIGHT INTO FRIDAY MORNING...THOUGH THE 17.12Z ECMWF HAS
DEVIATED FROM THAT WITH DEVELOPING A STRONGER SECONDARY MID LEVEL
TROUGH. THIS WOULD RUN THE PRECIPITATION LONGER AND HEAVIER THAN
WHAT WE ARE CURRENTLY FORECASTING...BUT HAVE SLOWED DOWN THE
EASTWARD PROGRESSION OF THE PRECIPITATION CHANCES A TAD.

BEYOND THAT...UPPER LEVEL RIDGING SETS UP FOR THE WEEKEND ON INTO
EARLY NEXT WEEK WITH THE REGION STAYING UNDER A COOL AIR MASS
BEFORE THE FLOW BECOMES MORE SOUTHWESTERLY TOWARD MID WEEK.  WITH
LITTLE TO NO INSTABILITY AROUND FOR THE NEXT SYSTEM THAT APPEARS
TO COME IN ON MONDAY NIGHT...HAVE REMOVED THE THUNDER MENTION FOR
THAT PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1133 PM CDT TUE SEP 17 2013

AS MEAN UPPER TROUGH CONTINUES TO PUSH INTO INTERMOUNTAIN WEST
RESPONSE IS BROAD AREA OF LIFT AND WARM AIR ADVECTION ACROSS
NORTHERN MIDWEST AND WESTERN GREAT LAKES. SATURATION HAS LED TO
LOWER CEILINGS AND VISIBILITIES OVER PARTS OF MINNESOTA AND IOWA
WHERE LIFR AND IFR CONDITIONS BEING OBSERVED. AHEAD OF THIS
ZONE...NORTH AND EAST OF THE BEST UPGLIDE...CEILINGS STAYING UP AT
MOMENT.

NOT TOO MUCH CHANGE IS EXPECTED OVERNIGHT WITH WORST CONDITIONS WEST
OF THE MISSISSIPPI RIVER...WHICH COULD WORSEN A BIT OVERNIGHT. IN
ADDITION LOW LEVEL JET AND ASSOCIATED MOISTURE TRANSPORT WILL
CONTINUE TO DEVELOP SCATTERED SHOWERS WHICH COULD LAST WELL THROUGH
WEDNESDAY MORNING.

LIFT SUBSIDES FOR A BIT LATER WEDNESDAY WITH SHORT TERM RIDGING.
THIS COULD ACTUALLY BRING IN SLIGHTLY DRIER AIR FROM THE WEST AND
ALLOW STRATUS TO BREAK UP FROM WEST TO EAST. BUFKIT SOUNDS CERTAINLY
HINT AT THIS POTENTIAL SO WILL TRY AND REMAIN OPTIMISTIC WITH
CONDITIONS RETURNING TO VFR AREA WIDE BY 00Z THURSDAY.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...SHEA







AREA FORECAST DISCUSSION

NWS PUEBLO CO

 1135 PM MDT THU SEP 19 2013

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 317 PM MDT THU SEP 19 2013

FAIRLY MEAGER CONVECTION OUT THERE SO FAR WITH DEW POINTS
STRUGGLING TO REBOUND ALONG THE NORTHERN PORTIONS OF THE AREA
BEHIND THIS MORNING`S COLD FRONT. THEY ARE SLOWLY CREEPING UP INTO
THE LOWER 40S TO MID 40S ACROSS EL PASO AND PUEBLO COUNTIES AS
WINDS SWING AROUND FROM THE EAST THIS AFTERNOON. FARTHER
EAST...DEW POINTS AT KLHX AND KLAA ARE STILL HOVERING IN THE 50S.
THUS HIGHEST MIXED LAYER CAPES OFF OF SPC MESO ANALYSIS IS RUNNING
AROUND 1000 J/KG ACROSS THE SOUTHEAST PLAINS SOUTH OF HIGHWAY
50...BUT THERE APPEARS TO BE A LITTLE CIN TO OVERCOME YET OUT THAT
WAY. AS THE UPPER TROF TRAILS ACROSS THE AREA THIS EVENING...SHORT
RANGE HIGH RES MODELS (LOCAL 4KM WRF...HRRR AND NAM12) ALL SHOW A
WINDOW FOR SOME ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE
SOUTHEAST MTS/SPREADING INTO THE ADJACENT PLAINS THROUGH THE
EVENING. WITH FORCING STILL COMING THROUGH ITS HARD TO ARGUE.
HOWEVER...HAVE NOTICED TREND IN HRRR TO DECREASE COVERAGE OF QPF
ACROSS THE SOUTHERN I-25 CORRIDOR WITH EACH RUN. AFTER MIDNIGHT
THINK MOST OF THE ACTIVITY WILL BE DONE...HOWEVER...LOW LEVEL
WINDS SWING AROUND FROM THE SOUTHEAST AND MODEL SOUNDINGS BECOME
DEEPLY SATURATED SUGGESTING POTENTIAL FOR LOTS OF LOW
CLOUDS...FOG...AND EVEN PATCHY DRIZZLE ALONG THE SOUTHERN SLOPES
OF THE PALMER DIVIDE WHERE UPSLOPE WILL BE MAXIMIZED. HAVE THROWN
IN SOME ISOLATED -SHRA AND DRIZZLE FOR THE LATE NIGHT/EARLY
MORNING HOURS ALONG WITH AREAS OF FOG ALONG THE I-25 CORRIDOR.

STRATUS WILL SLOWLY CLEAR ON FRIDAY...THOUGH THINK THAT SOUTHERN
SLOPES OF THE PALMER DIVIDE/COLORADO SPRINGS AREA MAY HANG ON TO
CLOUD COVER THROUGH THE MORNING BEFORE BREAKS START TO APPEAR IN THE
AFTERNOON...AS IS THE TYPICAL PATTERN FOR SOUTHERLY UPSLOPE CASES.
OTHERWISE...MODELS KEEP FORECAST AREA DRY FRIDAY AFTERNOON...WITH SE
PLAINS REMAINING CAPPED.  TEMPERATURES SHOULD BE ABOUT A CATEGORY COOLER THAN
THOSE OF TODAY. -KT

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 317 PM MDT THU SEP 19 2013

GENERALLY WARM AND DRY WEATHER STILL ON TRACK FOR THE EXTENDED...WITH
JUST A COUPLE OF STORM SYSTEMS TO CONTEND WITH. THE WEEKEND STARTS
OUT WARM AND DRY. SHOULD SEE 80S OVER THE PLAINS BOTH SAT AND SUNDAY.
GFS MOS CONTINUES TO LOOK TOO WARM FOR THE PLAINS...SO HAVE STAYED ON
THE COOL SIDE OF GUIDANCE...PARTICULARLY SUNDAY AS HIGH CLOUDS START
MOVING IN FROM THE WEST.

SOME MODEL DISCREPANCIES FOR OUR FIRST SHORT WAVE LATE SUNDAY. THE TREND
HAS BEEN TOWARDS A SLIGHTLY DEEPER OR SHARPER TROUGH...WHICH THE
ECMWF HAS BEEN ADVERTISING FOR A WHILE NOW. THE GFS NOW LOOKS
COOLER AND WETTER...AND WOULD BRING SEVERAL INCHES OF SNOW TO THE AREA
ABOVE 9K FEET SUNDAY NIGHT. THE NAM IS CONSIDERABLY WARMER AND
PROBABLY WOULD JUST LEAD TO TRACE SNOW AMOUNTS. THE TRUTH LIKELY IS
SOMEWHERE IN BETWEEN...BUT PROBABLY CLOSER TO THE GFS. SHOULD KNOW
BETTER BY TOMORROW OR FRIDAY IF THE NAM MOVES TOWARD A COOLER
SOLUTION. HAVE BUMPED UP POPS ABOUT 10-20 PERCENT AREA WIDE AS THE
TROUGH MOVES THROUGH SUN NIGHT.

MONDAY AND TUESDAY...THINGS REALLY DRY OUT IN ZONAL FLOW...AND WE
SHOULD SEE SOME REAL PLEASANT FALL WEATHER WITH LOTS OF SUNSHINE
AND TEMPS IN THE 70S-NR 80 FOR THE LOWLANDS AND 60S FOR THE HIGHER
VALLEYS. POPS ESSENTIALLY NIL EVEN FOR THE MTS.

NEXT SYSTEM BEGINS TO TAKE SHAPE ON WED THROUGH THU AS A DEEPER TROUGH
MOVES THROUGH THE PACNW AND INTO THE INTER-MOUNTAIN REGION. STILL PLENTY
OF UNCERTAINTY WITH THE TIMING AND DEPTH OF THIS LOW...BUT THE
TREND FOR A WHILE NOW HAS BEEN FOR IT TO LIFT INTO THE NRN ROCKIES
BY LATE THU OR FRI...WHICH WOULD BRING MOST OF THE PRECIP N OF OUR
CWA AND LEAVE US IN A DRY AND BREEZY CORNER. CERTAINLY DOES NOT
LOOK LIKE A BIG STORM FOR OUR AREA...BUT THE MTS SHOULD SEE AT
LEAST SOME LIGHT SNOWFALL ABOVE 9 OR 10K FEET AS H7 TEMPS DROP
CLOSE TO ZERO BY THE END OF THE WEEK. ROSE

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1130 PM MDT THU SEP 19 2013

A LOW STRATUS LAYER IS EXPECTED TO AFFECT KCOS AND KPUB
OVERNIGHT...WITH IFR CONDITIONS AND POSSIBLY SOME DRIZZLE. THE LOW
CLOUDS ARE EXPECTED TO CONTINUE THRU MUCH OF THE MORNING ON
FRIDAY...ESPECIALLY AT KCOS AS A SOUTH WIND DEVELOPS WITH THE
UPSLOPE FLOW POSSIBLY KEEPING A LOW CIG IN THE AREA THRU NOON OR A
LITTLE LATER. EXPECTING VFR CONDITIONS AT KALS THRU 24 HOURS.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...KT
LONG TERM...ROSE
AVIATION...28







AREA FORECAST DISCUSSION

NWS MIAMI FL

 128 AM EDT FRI SEP 20 2013

.AVIATION...AN AREA OF SHOWERS WITH BRIEF MVFR CONDITIONS WILL AFFECT
AREAS NEAR KTMB OVER THE NEXT HOUR OR SO. OTHERWISE, VFR WILL
PREVAIL THROUGH THE TAF FCST PERIOD AS DRIER AIR ON A NE WIND
MOVES INTO SOUTH FL. THERE COULD BE A FEW SHOWERS OR TSTORMS,
MAINLY TOWARDS THE GULF COAST THIS AFTERNOON, BUT COVERAGE AND
CONFIDENCE IS LOW SO KEPT ANY MENTION OUR OF THE TAFS. NE WINDS
WILL PICK UP WITH GUSTS OF AROUND 15 KT THIS AFTERNOON. /GREGORIA

&&

.PREV DISCUSSION... /ISSUED 811 PM EDT THU SEP 19 2013/

UPDATE...
SCATTERED MODERATE RAIN SHOWERS ALONG WITH A FEW EMBEDDED
THUNDERSTORMS CONTINUE TO PUSH ONSHORE THE EAST COAST ALONG MAINLY
BROWARD AND PALM-BEACH COUNTIES THIS EVENING UNDER NORTHEAST FLOW.
SHORT TERM GUIDANCE GRADUALLY DISSIPATES THESE SHOWERS AS THEY
CONTINUE TO PUSH TO THE SOUTHWEST APPROACHING THE INTERIOR. MORE
ORGANIZED CONVECTION JUST NOW EXITING THE SOUTHERN MOST GULF
MARINE ZONE WILL CONTINUE TO PUSH SOUTH TOWARD THE FLORIDA KEYS.
KEPT POPS ON A GRADUAL DOWNWARD TREND ACROSS THE AREA THROUGH THE
NIGHT.

PREV DISCUSSION... /ISSUED 709 PM EDT THU SEP 19 2013/

AVIATION...
ISOLATED SHOWERS ARE EXPECTED TO MOSTLY DISSIPATE BY 0Z...SO RAIN-
FREE TAFS AT ALL SITES THROUGH 0Z SAT. ISOLATED SHOWERS POSSIBLE
ANYTIME...ESPECIALLY MIDDAY FRIDAY...BUT EXPECTED COVERAGE AND
CONFIDENCE IS FAR TO LOW TO WARRANT INCLUSION OF VCSH ATTM. VFR
CONDITIONS PREVAIL. NE WINDS 5-10 KTS OVERNIGHT WILL INCREASE TO
10-15 KTS ON FRIDAY.

PREV DISCUSSION... /ISSUED 227 PM EDT THU SEP 19 2013/

SHORT TERM (TONIGHT-SATURDAY NIGHT)...
THIS EVENING...THE LATEST RADAR SCAN SHOWED SCATTERED ACTIVITY
DEVELOPING OVER THE INTERIOR AREAS SPREADING WESTWARD TOWARD THE
GULF COAST. THE LATEST HRRR MODEL RUNS LINE UP WELL WITH THIS AND
INDICATE THIS ACTIVITY BECOMING FOCUSED OVER AND AROUND THE GULF
COAST AREAS THROUGH THE LATE AFTERNOON AND EVENING HOURS ONCE AGAIN.
CONSIDERING THE EXTENSIVE RAINFALL COVERAGE OVER THE GULF COAST
YESTERDAY...THE MAIN CONCERN THROUGH THIS EVENING WILL BE THE
POTENTIAL FOR ADDITIONAL HEAVY RAINFALL AND FLOODING DUE TO THE
SATURATED GROUNDS.

FRIDAY THROUGH SATURDAY NIGHT...THE LATEST NUMERICAL GUIDANCE
REMAINS IN DECENT AGREEMENT THROUGH THIS PERIOD AND SHOWS WHAT IS
LEFT OF THE WEAKENING BOUNDARY OR TROUGH CURRENTLY MOVING INTO
THE AREA CONTINUING SOUTH WITH SOME DRIER AIR FILLING IN BEHIND IT
FROM THE NORTH. THIS COMBINED WITH THE MEAN LOW-LEVEL FLOW UP TO
10 KFT SHIFTING TO THE NORTH WILL TRANSLATE TO LOWER RAINFALL
CHANCES EACH DAY. DEWPOINTS COULD REACH THE LOWER 60S ACROSS
PORTIONS OF THE INTERIOR AREAS SATURDAY AFTERNOON. MODEL SOUNDINGS
INDICATE PRECIPITABLE WATER VALUES DIPPING DOWN TO AROUND 1.3"
ACROSS PORTIONS OF THE AREA BY SATURDAY. TEMPERATURES ARE FORECAST
TO REMAIN AROUND NORMAL THROUGH THIS PERIOD...WITH THE EXCEPTION
BEING THE POSSIBILITY OF REACHING THE UPPER 60S ACROSS THE
NORTHERN INTERIOR AREAS BY DAYBREAK SATURDAY MORNING.

LONG TERM (SUNDAY-WEDNESDAY)...
AN UPPER TROUGH IS FORECAST TO DIG ACROSS THE SOUTHEAST AND
EASTERN SEABOARD THROUGH THE SECOND HALF OF THE WEEKEND. OUT AHEAD
OF THIS...SURFACE AND LOW LEVEL FLOW WILL SHIFT TO THE
SOUTH...BRINGING A SURGE OF MOISTURE BACK INTO SOUTH FLORIDA ON
SUNDAY. MODELS HAVE BEEN TRENDING TOWARDS A WEAKER LOW LEVEL/SURFACE
REFLECTION ACROSS THE SOUTHEAST...AND THUS A WEAKER COLD FRONT
MOVING INTO THE SOUTHEAST STATES. THE ECMWF IS NOW STRONGER THAN THE
GFS WITH THE BAROCLINIC SURFACE LOW ACROSS THE NORTHERN GULF
COAST/SOUTHEAST STATES...AND DRAWS THE MOISTURE FROM THE BAY OF
CAMPECHE SYSTEM TO THE NORTHEAST. REGARDLESS...SINCE THE MODELS HAVE
TRENDED SLOWER WITH THE COLD FRONT AND KEEP IT ACROSS NORTH FLORIDA
THROUGH EARLY NEXT WEEK...THE FOCUS FOR STORMS MAY BE ACROSS THE
GULF WATERS AND NORTH OR CENTRAL FLORIDA. WITH NO FOCUS FOR RAINFALL
ACROSS SOUTH FLORIDA AND EXTENSIVE CLOUD COVER POSSIBLY LIMITING
RAINFALL AMOUNTS DURING THE DAY MONDAY AND TUESDAY...THE HEAVIEST
RAINS MAY ACTUALLY FALL OVER THE NIGHT TIME HOURS AS SPEED/COASTAL
CONVERGENCE SETS UP. THE GFS AND ECMWF ARE HINTING AT THIS AS
WELL. SO RAINFALL CHANCES WILL LIKELY REMAIN HIGH SUNDAY THROUGH
TUESDAY. THE FORECAST IS UNCLEAR BEYOND THAT POINT...BUT RAINFALL
CHANCES WILL REMAIN ELEVATED THROUGH AT LEAST WEDNESDAY.

MARINE...
LIGHT TO MODERATE NORTHEAST WINDS WILL CONTINUE THROUGH SATURDAY AS
A WEAKENING FRONTAL BOUNDARY SHIFTS SOUTH INTO THE AREA. WINDS WILL
SHIFT TO THE SOUTH THROUGH THE SECOND HALF OF THE WEEKEND AND INTO
EARLY NEXT WEEK AS ANOTHER FRONTAL BOUNDARY APPROACHES FROM THE
NORTH. SEAS OVER THE ATLANTIC WATERS SHOULD BEGIN TO SUBSIDE OVER
THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  74  88  75  89 / 10 10 10 50
FORT LAUDERDALE  77  89  77  90 / 10 10 10 50
MIAMI            75  89  77  90 / 10 10 20 50
NAPLES           73  90  75  88 / 10 20 30 60

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&

$$





AREA FORECAST DISCUSSION

NWS NORTHERN INDIANA

 141 AM EDT FRI SEP 20 2013

.SYNOPSIS...
ISSUED AT 819 PM EDT THU SEP 19 2013

A WARM FRONTAL BOUNDARY MOVING THROUGH THE AREA TONIGHT COMBINED
WITH ADDITIONAL WEAK UPPER LEVEL DISTURBANCES WILL RESULT IN A
CONTINUED CHANCE OF THUNDERSTORMS THROUGH EARLY FRIDAY
MORNING...PARTICULARLY ACROSS NORTHWEST AND NORTH CENTRAL INDIANA
ALONG WITH SOUTHERN LOWER MICHIGAN. A STRONG UPPER LEVEL SYSTEM
WILL APPROACH THE GREAT LAKES REGION FRIDAY ALLOWING A COLD FRONT
TO MOVE INTO THE AREA. THIS WILL RESULT IN A LIKELIHOOD OF SHOWERS
AND THUNDERSTORMS FRIDAY AND FRIDAY NIGHT. DRY CONDITIONS WILL
RETURN FOR SATURDAY...WITH MUCH COOLER CONDITIONS BEHIND THE COLD
FRONT.

&&

.UPDATE...
ISSUED AT 819 PM EDT THU SEP 19 2013

EARLIER SCATTERED THUNDERSTORMS WHICH DEVELOPED IN VICINITY OF
SURFACE TROUGH/WARM FRONT FEATURE HAVE DIMINISHED OVER PAST FEW
HOURS AS LOW LEVEL CIN HAS INCREASED. RUC 00Z ANALYSIS STILL
DEPICTS AXIS OF 2000-2500 J/KG OF 100 HPA MLCAPES FROM EXTREME
WEST CENTRAL INDIANA INTO NORTHEAST ILLINOIS ALONG BROAD LOW LEVEL
CONFLUENCE ZONE. MORE ORGANIZED CONVECTIVE ACTIVITY REMAINS ACROSS
THE MID MS RIVER VALLEY AND APPROACHING THE WESTERN GREAT LAKES
WITH SEVERAL OUTFLOWS ASSOCIATED WITH THIS ACTIVITY. HAVE
MAINTAINED TREND OF INCREASING POPS TO MID TO HIGH CHANCE AGAIN
OVERNIGHT ACROSS THE NORTHWEST AS SMALLER SCALE PERTURBATIONS KICK
OUT OF CENTRAL CONUS TROUGH...WITH RESIDUAL OUTFLOW BOUNDARIES
PERHAPS PROVIDING SOME FOCUS. ONLY CHANGE TO PREVIOUS FORECAST WAS
TO MAKE SMALL ADJUSTMENTS IN LOWERING EVENING POPS FOLLOWING
OBSERVATIONAL TRENDS AND DECAY OF LATE AFTERNOON CONVECTION.

&&

.SHORT TERM...(LATE THIS AFTERNOON THROUGH FRIDAY)
ISSUED AT 347 PM EDT THU SEP 19 2013

MAIN FOCUS FOR THE REMAINDER OF THE AFTERNOON WILL BE ON BATCH OF
RAIN/THUNDER THAT WILL CONTINUE TO SINK SOUTHEAST THROUGH THE IWX
CWA. THIS ACTIVITY IS TIED TO A WEAK MCV NOW INTO WESTERN
MICHIGAN...WHICH HAS HELPED ENHANCE DEEP MOIST CONVERGENCE ALONG A
SFC WARM FRONT THAT HAS MIXED INTO OUR FAR SOUTHWESTERN CWA AS OF
19Z. THERE IS SOME CONCERN FOR AN ISOLATED STRONG/SEVERE CELL
ALONG THIS SFC FRONT SOUTH OF HWY 30 AND WEST OF HWY 15 IN INDIANA
GIVEN MORE PRONOUNCED LOW LEVEL CONVERGENCE AND MODERATE MLCAPE
VALUES HERE. MARGINAL DEEP LAYERED FLOW/SHEAR WILL KEEP THIS AN
ISOLATED WIND/HAIL THREAT. SMALL MBE VECTORS/TRAINING WITH PWAT
VALUES NEAR 1.80 INCHES MAY SUPPORT SOME ADDITIONAL LOCALIZED
FLOODING/HEAVY RAIN ACROSS MAINLY OUR INDIANA ZONES INTO THE LATE
AFTERNOON.

MCS SHOULD SETTLE SOUTH AND EAST OF THE LOCAL AREA THIS EVENING INTO
THE OVERNIGHT...LEAVING A WEAK LOW LEVEL BOUNDARY DRAPED OVER THE
AREA IN ITS WAKE. CHANCES FOR ISOLATED TO SCATTERED CONVECTION INVOF
THIS BOUNDARY APPEAR RATHER LOW THIS EVENING BUT INCREASE A BIT
LATER TONIGHT AS A SMALLER SCALE LEAD SHORTWAVE EJECTS OUT OF THE
CENTRAL HIGH PLAINS AND PROPAGATES INTO THE MISSOURI VALLEY AND
WESTERN GREAT LAKES. AFTERNOON WATER VAPOR ALSO SHOWS TROPICAL
MOISTURE FROM HURRICANE MANUAL BEING PICKED UP INTO THE SOUTHERN
PLAINS IN ADVANCE OF THIS FEATURE AND UPPER TROUGH. THIS SECONDARY
SHOT OF MOISTURE ADVECTION AND NARROW RIBBON OF CYCLONIC VORTICITY
MAY BE ENOUGH TO GENERATE ADDITIONAL SCATTERED CONVECTION BY
LATER TONIGHT...BEST CHANCES ACROSS NORTHWEST INDIANA AND SW LOWER
MICHIGAN.

AN UPPER LEVEL TROUGH ACROSS THE CANADIAN PRAIRIES AND NORTHERN HIGH
PLAINS WILL AMPLIFY EAST INTO THE UPPER MIDWEST AND MID MS VALLEY BY
TOMORROW. DEEPENING SFC REFLECTION IN AREA OF STRONGER CYCLONIC
VORTICITY ADVECTION DOWNSTREAM OF TROUGH AXIS WILL TRACK
NORTHEAST THROUGH THE NORTHERN GREAT LAKES AND ONTARIO. THIS WILL
FORCE A TRAILING COLD FRONT INTO OUR NORTHWESTERN ZONES FRIDAY
MORNING AND CENTRAL/EASTERN ZONES BY FRIDAY AFTERNOON. CHANCES FOR
SHOWERS/STORMS STILL LOOKING GOOD INVOF THE FRONT GIVEN 60-80
METER 500 MB HEIGHT FALLS OVER DEEP PRE-FRONTAL MOISTURE PLUME
(PWATS AT LEAST 1.75 INCHES AND 1000-850 MB MIXING RATIOS NEAR 14
G/KG). THERE COULD BE A LULL IN COVERAGE/INTENSITY OF SHOWERS IN
THE MORNING BEHIND THE AFOREMENTIONED LEAD WAVE...BUT EXPECT THIS
TO FILL BACK IN WITH SOME HEATING AS DEEPER TROPOSPHERIC ASCENT
PIVOTS IN. LOCALIZED HEAVY RAIN WILL CONTINUE TO BE A
CONCERN...ESPECIALLY IN AREAS THAT HAVE ALREADY SEEN HEAVY RAIN
TODAY. SPC HAS AREAS ALONG/EAST OF A KOKOMO-WARSAW-COLDWATER LINE
HIGHLIGHTED IN A SLIGHT RISK FOR SEVERE STORMS TOMORROW AFTERNOON.
STRONG FRONTAL SCALE FORCING COMBINED WITH THE POTENTIAL FOR WEAK
TO MODERATE BOUNDARY LAYER DESTABILIZATION MAY SUPPORT SOME
OVERACHIEVING UPDRAFTS...ALTHOUGH STRONGER FLOW/SHEAR NEEDED FOR
UPDRAFT/DOWNDRAFT SEPARATION AND ORGANIZATION WILL LIKELY LAG JUST
BEHIND THE FRONT. THUS...EXPECT LINGERING CLOUD COVER AND MARGINAL
SHEAR TO LIMIT THIS TO AN ISOLATED WIND/HAIL THREAT AT BEST.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 345 PM EDT THU SEP 19 2013

STRONG UPR LEVEL TROF OVER THE NRN PLAINS THIS AFTN WILL MOVE INTO
THE GRTLKS FRI NGT WHILE ACCOMPANYING CDFNT OUT AHEAD OF THE UPPER
FEATURE MOVES TO THE EAST OF THE CWA OVERNIGHT. MODELS IN GOOD
AGREEMENT THAT SHOWERS/TSTMS WILL BE ONGOING NEAR THE FRONT FRI EVE
SO BUMPED UP POPS IN THE EAST TO CATEGORICAL FOR THAT TIMEFRAME.
NAM/SREF A LITTLE QUICKER TO MOVE FRONT EAST OF THE CWA OVERNIGHT.
PREFER SLOWER GFS/ECMWF WHICH HAVE HAD BETTER RECENT RUN-RUN
CONTINUITY IN THIS REGARD... THUS MAINTAINED DIMINISHING RAIN
CHANCES OVERNIGHT WITH A SMALL CHC INTO EARLY SAT MORNING FAR EAST.
GFS/ECMWF SUGGESTING SOME POST-FRONTAL/LAKE ENHANCED SHOWERS PSBL
NWRN PORTION OF THE CWA SATURDAY AS UPR TROF SWINGS EAST THROUGH
LOWER MICHIGAN AND DELTA T`S INCREASE TO NEAR 13C. PREFER DRY
NAM/SREF SOLUTION IN OUR AREA AS AIRMASS IS FCST BY ALL MODELS TO BE
FAIRLY DRY... ESPECIALLY ALOFT... AND SUBSIDENCE INVERSION LEVEL
ONLY AROUND 5KFT. SFC HIGH FOLLOWING THE FRONT IS EXPECTED TO MOVE
ESE ACROSS THE UPR GRTLKS OVER THE REMAINDER OF THE WEEKEND
PROVIDING COOL/DRY WX. MODELS HAVE TRENDED A LITTLE MORE AMPLIFIED
WITH THE UPR FLOW AND ASSOCIATED LOW LEVEL CAA THIS WEEKEND... THUS
MADE MINOR DOWNWARD ADJUSTMENTS TO TEMPS WITH HIGHS FCST IN THE
L-M60S AND LOWS IN THE L-M40S.

UPR LEVEL RIDGE EXPECTED TO BUILD INTO THE GRTLKS REGION BY MONDAY
AND PERSIST THROUGH THURSDAY AS A SERIES OF SHRTWVS DIG SEWD FROM
THE NE PACIFIC INTO THE WRN U.S.. THIS SHOULD RESULT IN DRY WX
ACROSS OUR CWA THROUGH THIS PERIOD WITH TEMPS WARMING TO ABOVE
NORMAL READINGS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 140 AM EDT FRI SEP 20 2013

STRONG COLD FRONT WILL MOVE THROUGH THE AREA LATER TODAY.
ABUNDANT MOISTURE AND UPPER LEVEL DYNAMICS COUPLED WITH
CONVERGENCE ALONG FRONT SHOULD LEAD TO SHOWERS AND POSSIBLE
THUNDERSTORMS AT TAF SITES TODAY. MOIST AIR AND WEAK LIFT LEADING
TO SOME WIDELY SCATTERED LIGHT SHOWERS ON RADAR AT ISSUANCE. A FEW
OF THESE LIKELY TO MOVE THROUGH TAF SITES BUT CURRENT TRENDS
SUGGEST NO RESTRICTIONS. BETTER FORCING ARRIVES LATER THIS MORNING
AND LINGERS THROUGH AFTERNOON WHEN FRONT FINALLY PASSES. DRIER AIR
FILTERS IN TONIGHT. WRAP AROUND STRATOCUMULUS POSSIBLE AND KEPT
CIGS OPTIMISTIC AND VFR FOR TONIGHT.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

UPDATE...MARSILI
SYNOPSIS...MARSILI
SHORT TERM...STEINWEDEL
LONG TERM...JT
AVIATION...LASHLEY


VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)

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AREA FORECAST DISCUSSION

NWS QUAD CITIES IA IL

 333 AM CDT FRI SEP 20 2013

.SYNOPSIS...
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN AREA OF SHOWERS AND THUNDERSTORMS HAS PUSHED TO EAST OF THE
DVN CWA THIS MORNING AHEAD OF THE PREFRONTAL TROUGH OVER EASTERN
IOWA AND THE COLD FRONT STRETCHES FROM CENTRAL LAKE SUPERIOR
SOUTHWARD THROUGH SOUTHEASTERN MINNESOTA AND CENTRAL IOWA AT THIS
TIME. SCATTERED SHOWERS AND LOW CEILINGS HAVE DEVELOPED ALONG THE
PREFRONTAL TROUGH THIS MORNING ASSOCIATED WITH THE CONVERGENCE ALONG
IT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN FORECASTS CONCERNS THIS MORNING WILL BE THE SCATTERED
SHOWERS ALONG THE PREFRONTAL TROUGH AND THE LOW CEILINGS.

THE MAIN AREA OF PRECIPITATION HAS MOVED INTO EASTERN ILLINOIS EARLY
THIS MORNING WITH A WEAK AREA OF SHOWERS AND LOW CEILINGS ALONG THE
PREFRONTAL TROUGH. THE 13 KM RAP HAD STRONG CONVERGENCE ALONG THIS
FEATURE EARLY THIS MORNING AND SHOWS THE CONVERGENCE WEAKENING
THROUGH 12 UTC AS BOUNDARY SHIFTS EASTWARD. THE THREAT OF SHOWERS
FROM THIS FEATURE SHOULD QUICKLY DIMINISH BY 12 UTC. THE COLD FRONT
WILL EXIT INTO CENTRAL ILLINOIS BY 15 UTC WITH STRONG COLD ADVECTION
USHERING IN MUCH COOLER AIR THAN WE HAVE EXPERIENCED OVER THE PAST
48 HOURS AND CLOSER TO NORMAL HIGH TEMPERATURES FOR MID SEPTEMBER.

CLOUDS WILL CLEAR QUICKLY THROUGH THE DAY ON FRIDAY AS DRIER AIR
MOVES INTO THE REGION. HOWEVER THERE IS SOME CONCERN THAT THE
STRATUS LAYER CURRENTLY OVER THE EASTERN DAKOTAS WILL MOVE
SOUTHEASTWARD AND INTO THE REGION FRIDAY NIGHT INTO SATURDAY
MORNING. MODELS CONTINUE TO SUGGEST THAT THE CLOUDS WILL DISSIPATE
SO WILL LEAVE THE FORECAST CLEAR OVERNIGHT. THIS PLAYS DIRECTLY INTO
THE TEMPERATURE FORECAST FOR SATURDAY MORNING AND HAVE NOT MADE ANY
CHANGES TO THE PREVIOUS FORECAST FOR LOW TEMPERATURES IN THE MID TO
UPPER 40S. IF STRATUS DOES MOVE INTO THE REGION LOW TEMPERATURES ON
SATURDAY MORNING MAY BE WARMER THAN CURRENTLY FORECAST.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 327 AM CDT FRI SEP 20 2013

NEARLY IDEAL OUTDOOR FALL WEATHER WILL GRACE THE EXTENDED FORECAST
EACH DAY. SURFACE HIGH PRESSURE OVER THE GREAT LAKES WILL DOMINATE
THE WEATHER THROUGH THE NEXT 4 DAYS...WITH A DRY FROPA
TUESDAY...FOLLOWED BY ANOTHER PLEASANT HIGH PRESSURE SYSTEM. THOSE
WITH HOPE FOR MORE RAIN WILL HAVE TO WAIT ON A SINGLE COLD FROPA
EVENT WHICH IS FORECAST BY THE GFS AND ECMWF TO OCCUR AROUND FRIDAY
NIGHT BEYOND OUR CURRENT DAY 7.  THE TUESDAY TROF PASSAGE...SHOULD
BE MOISTURE STARVED...AND MAY ONLY BRIEFLY INCREASE HIGH LEVEL CLOUD
COVER.

LARGE DIURNAL SPREADS ARE FORECAST UNDER THE HIGH PRESSURE FOR
SATURDAY THROUGH MONDAY...WITH HIGHS IN THE MID 60S TO LOWER 70S AND
LOWS QUITE COOL...IN THE LOWER TO UPPER 40S IN GENERAL. THIS
TEMPERATURE RANGE REPRESENTS READINGS A FEW DEGREES BELOW CLIMATE
NORMALS...AND IS ONLY SIGNIFICANT IN COMPARISON TO OUR RECENT RECORD
WARMTH AND HUMIDITY. BEYOND MONDAY...MODEL BLENDS CONTINUE TO
INDICATE MODERATION...HOWEVER...I AM UNCERTAIN THAT THIS IS ACTUALLY
GOING TO OCCUR GIVEN OUR POTENTIAL FOR HAVING SOUTHEAST SURFACE FLOW
UNDER THE BUILDING UPPER RIDGE OF HIGH PRESSURE. THIS TRAJECTORY
COULD KEEP THE WIDE DIURNAL TEMPERATURE RANGES GOING...ALONG WITH
TEMPERATURES CLOSE TO NORMAL. WILL PASS THIS CONCERN ON THE THE NEXT
SHIFT WHICH SHOULD BE ABLE TO MORE FORMALLY PLACE THIS INTO THE
FORECAST BLEND.
ERVIN


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1144 PM CDT THU SEP 19 2013

AN AREA OF LIGHT TO MODERATE RAIN WITH ISOLATED THUNDER ALONG AND
EAST OF THE MISSISSIPPI RIVER WILL GRADUALLY EXIT THE REGION EARLY
THIS MORNING. A COLD FRONT WILL MOVE THROUGH BEFORE SUNRISE. PATCHY MVFR
AND IFR CIGS WILL PRECEDE THE FRONT. BY 12Z THE FRONT WILL BE
EAST OF THE AREA WITH VFR CONDITIONS EXPECTED BEHIND THE FRONT.
POST FRONTAL NORTHWEST WINDS WILL GUST TO AROUND 20KTS DURING THE
LATE MORNING AND AFTERNOON.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...DC
SHORT TERM...DC
LONG TERM...ERVIN
AVIATION...DLF







AREA FORECAST DISCUSSION

NWS GOODLAND KS

 323 AM MDT FRI SEP 20 2013

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 323 AM MDT FRI SEP 20 2013

INITIAL FORECAST CONCERN WILL BE TEMPERATURES THROUGH THE WEEKEND
...WINDS THROUGH THE WEEKEND...ESPECIALLY ON SUNDAY...WITH THE LAST
PROBLEM THE NEXT CHANCE FOR PRECIPITATION AT THE BEGINNING OF NEXT
WEEK. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH
AMERICA. OVER THE LAST 24 HOURS THE FLOW FROM THE CENTRAL PACIFIC
INTO NORTH AMERICA HAS AMPLIFIED. AT LOW LEVELS TWO DIFFERENT COLD
FRONTS HAVE BROUGHT IN A DRIER AND COOLER AIR MASS INTO THE AREA.

AT JET LEVEL...THE SREF FOLLOWED BY THE GFS WAS DOING THE BEST. AT
MID LEVELS...THE NAM WAS DOING A LITTLE BETTER THAN THE GFS...UKMET
AND CANADIAN. THE RUC FOLLOWED BY THE SREF AND THE NAM/ECMWF WAS
DOING THE BEST ON THE SURFACE WIND AND PRESSURE FIELD. THE GFS
FOLLOWED BY THE UKMET THEN SREF/NAM DID THE BEST ON THE LOW LEVEL
THERMAL FIELD.

TODAY/TONIGHT...WEAK SHOWERS AND THUNDERSTORMS HAVE POPPED NEAR THE
SOUTHERN AND WESTERN END OF THE FORECAST AREA. MODELS DO SHOW A RIGHT
REAR QUADRANT OF THE JET HANGING AROUND THROUGH THE MORNING AND IT
WILL BE ON TOP OF A WEAK MID LEVEL BAROCLINIC ZONE NEAR 700 MB.
WEAK FRONTOGENESIS IS IN THIS LAYER AS WELL WITH FAVORABLE THETA-E
LAPSE RATES. BASED ON LATEST TRENDS/MODEL DATA...WILL INCLUDE A
MENTION OF SPRINKLES...MOSTLY IN THE SOUTHERN HALF THROUGH MID
MORNING.

IN THE NORTHERN TIER OF COUNTIES...LACK OF CLOUD COVER HAS
ALLOWED TEMPERATURE/DEWPOINT SPREADS TO BE VERY SMALL. HAVE ALREADY
SEEN PATCHY FOG IN SOME LOCATIONS. WHERE PRECIPITATION AND CLOUD
COVER ARE NOT EXPECTED...WILL PUT IN A MENTION OF PATCHY FOG ALSO
THROUGH MID MORNING. AT THIS TIME IT LOOKS LIKE CLOUD COVER WILL
DECREASE BY LATE MORNING. BASED ON TEMPERATURE BIASES AND CHANGE
OVER THE LAST 24 HOURS COMBINED WITH WHAT HAS BEEN DOING BEST ON
MAXES...MADE SOME ADJUSTMENTS UP FROM THE PREVIOUS FORECAST FOR THE
HIGH TEMPERATURES. MINS WILL BE WARMER TONIGHT DUE TO STRONGER
WINDS.

SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING TO
THE EAST WITH STRONG CROSS MOUNTAIN FLOW DEVELOPING. DURING THE LAST
HALF OF THE NIGHT THE MODELS SHOW THAT A LEFT FRONT QUADRANT
APPROACHES FROM THE SOUTH. THIS COULD SPREAD SOME HIGHER LEVEL CLOUDS
INTO THE AREA...ESPECIALLY IN THE SOUTHERN HALF. DUE TO A DRY AND
WELL MIXED AIR MASS...WILL KEEP THIS PERIOD DRY.

AS THE RESULT OF THE STRONG CROSS MOUNTAIN AND INCOMING UPPER
TROUGH MOVING INTO THE GREAT BASIN...LEE TROUGH WILL BEGIN TO
STRENGTHEN. INCREASING GRADIENT AND EXPECTED 3 HOUR PRESSURE FALLS
WOULD SUPPORT BREEZY SOUTHERLY WINDS DEVELOPING ACROSS THE AREA
DURING THE DAY. THERE WILL BE PLENTY OF SUN TO ALLOW HEATING AS 850
MB TEMPERATURES INCREASE 3 TO 5 DEGREES C FROM THE PREVIOUS DAY. SO
BASED ON THAT...RECENT BIASES...AND BETTER PERFORMING GUIDANCE...
RAISED THE MAXES ACCORDINGLY. LOW TEMPERATURES COULD STAY RATHER
MILD AS ATMOSPHERE STAYS WELL MIXED DUE TO STRENGTHENING LEE TROUGH.

SUNDAY/SUNDAY NIGHT...MODELS THEN START DIVERGING IN HOW THEY HANDLE
INCOMING UPPER TROUGH IN REGARDS TO SPEED AND AMPLITUDE. THIS
AFFECTS NUMEROUS PARAMETERS/FIELDS OF THE FORECAST. CURRENTLY THE
PATTERN OUT IN THE PACIFIC IS RATHER AMPLIFIED WITH A STRONG JET
STILL COMING DOWN THE WEST SIDE OF THE INCOMING UPPER TROUGH. THAT
WOULD SUPPORT HAVING A SLOWER AND MORE AMPLIFIED INCOMING UPPER
TROUGH. THIS PRETTY MUCH DISCOUNTS THE NAM AND THE SREF ARE VERY
FAST. MOST OF THE REMAINING OUTPUT IS CLOSE TO EACH OTHER ON THE
POSITION OF THE UPPER TROUGH AND RESULTING SURFACE PATTERN. GEFS
OUTPUT IS ALSO VERY SUPPORTIVE OF THE SLOWER SOLUTIONS WHICH ARE
THE GFS...ECMWF...UKMET AND CANADIAN.

SO WILL BASE FORECAST ON THOSE BUT CONFIDENCE IS A LITTLE BELOW
AVERAGE. MAIN SURFACE CONVERGENCE LIES NEAR THE WESTERN PORTION OF
THE FORECAST AREA ALONG WITH ACCOMPANYING MID/UPPER LIFT. CAP IS
ALSO THE WEAKEST THERE AS WELL. ALL THIS PLUS THE DETERMINISTIC QPF
AND GEFS PROBABILITY OF .05 SUPPORTS PULLING THE CHANCE OF
THUNDERSTORMS FURTHER WEST IN THE AFTERNOON. SO ADJUSTED THAT
ACCORDINGLY. AS STATED IN THE PREVIOUS FORECAST...MOISTURE COULD BE
THE LIMITING FACTOR ON COVERAGE AND SEVERITY. HOWEVER...LAPSE RATES
ARE VERY GOOD WITH VERY STRONG MID/UPPER LEVEL INDICATED...MAINLY
DURING THE EVENING. VERY STRONG PV ANOMALY ASSOCIATED WITH THIS
SYSTEM. PREVIOUS FORECAST HAS HIGH CHANCE IN THERE AND CONSIDERING
THE UNCERTAINTY BUT THE STRENGTH OF THE SYSTEM...FELT IT WAS
REASONABLE TO KEEP THOSE POPS.

VERY STRONG SYSTEM APPROACHING WILL CAUSE THE LEE TROUGH TO
STRENGTHEN EVEN MORE. PRESSURE GRADIENT AND 3 HOUR PRESSURE FALLS
DEFINITELY SUPPORT WINDY/NEAR WIND ADVISORY CONDITIONS. SO INCREASED
WIND SPEEDS TO NEAR WIND ADVISORY. 850 MB TEMPERATURES SUPPORT
HAVING HIGH TEMPERATURES NEAR WHAT THE EXPECTED SATURDAY MAXES ARE.
SO ADJUSTED ACCORDINGLY.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 301 AM MDT FRI SEP 20 2013

EARLY MONDAY...ECMWF AND GFS PLACE THE UPPER LEVEL SHORTWAVE TROUGH
AXIS OVER NORTHEAST COLORADO WITH THE COLD FRONT BISECTING THE
FORECAST AREA. THE NAM IS THE MUCH FASTER OUTLIER AND PER WPC
MODEL DIAGNOSTICS DISCUSSION A BLEND OF THE GFS AND ECMWF IS
FAVORED FOR POSITION/TIMING. SHOWERS AND THUNDERSTORMS SHOULD BE
LIMITED TO THE EASTERN HALF OF THE FORECAST AREA MONDAY
MORNING...POSSIBLY THROUGH EARLY AFTERNOON DEPENDING ON TIMING.

AS THE SHORTWAVE TROUGH MOVES QUICKLY NORTHEAST...STRONG WESTERLY
MID/UPPER FLOW DEVELOPS OVER THE NORTHERN ROCKIES AND NORTHERN
PLAINS BY TUESDAY AND LEE SIDE TROUGH STRENGTHENS IN RESPONSE. VERY
SUBTLE UPPER LEVEL RIDGING MAY BE PRESENT ON TUESDAY BUT NOT ENOUGH
FOR TEMPERATURES TO SIGNIFICANTLY EXCEED NORMAL VALUES. A
SIGNIFICANT UPPER TROUGH WILL DEVELOP OVER THE WESTERN CONUS BY
WEDNESDAY. MODELS DISAGREE ON THE TIMING AND POSITION OF THIS
TROUGH...ALBEIT TO A LESSER EXTENT THAN PREVIOUS RUNS. GFS IS THE
QUICKEST AT EJECTING IT NORTHEASTWARD. EVEN SO...GFS ENSEMBLE MEAN
QPF REMAINS NORTH AND NORTHWEST OF THE FORECAST AREA THROUGH THE END
OF THE EXTENDED PERIOD...SO THE FORECAST REMAINS DRY BEYOND MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1147 PM MDT THU SEP 19 2013

VFR CONDITIONS WITH MOSTLY CLEAR SKIES WILL PREVAIL THROUGH THE
TAF PERIOD AT BOTH MCK AND GLD. LIGHT AND VARIABLE WINDS WILL BE
OBSERVED DURING THE REMAINDER OF TONIGHT AND INTO FRIDAY MORNING
WITH SURFACE HIGH PRESSURE OVER THE CENTRAL HIGH PLAINS REGION.
WINDS WILL BECOME LIGHT SOUTH TO SOUTHWEST AFTER 18Z AS THE HIGH
CENTER MOVES EAST OVER THE PLAINS STATES AND A LEE SURFACE TROUGH
BEGINS TO DEEPEN ALONG THE FRONT RANGE.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.

&&

$$

SHORT TERM..BRB
LONG TERM...BULLER
AVIATION...LOCKHART





AREA FORECAST DISCUSSION

NWS DODGE CITY KS

 1208 AM CDT Fri Sep 20 2013

...UPDATE TO AVIATION...

.SYNOPSIS...
ISSUED AT 950 PM CDT THU SEP 19 2013

Water vapor imagery and 00Z upper air analysis indicate an upper
level trough of low pressure drifting eastward across the Dakotas.
Meanwhile, upper level ridging is moving eastward across the
Intermountain West. Near the surface, a cold front extends from
the Texas Panhandle northeast into eastern Kansas. Cooler and
drier air has filtered south into western Kansas lowering surface
dewpoints primarily down into the 50s(F) with a few mid to upper
40s(F) closer to the Colorado border.

&&

.SHORT TERM...(This evening through Friday)
ISSUED AT 145 PM CDT THU SEP 19 2013

Based on 18z surface analysis the surface cold front was
progressing across western Kansas slightly quicker than what the
12z GFS and 12z NAM suggested. The latest HRRR and RAP seems to be
tracking the front a little better earlier this afternoon so will
follow these models for the frontal location between 21z and 00z.
Convection is expected to begin to initiate near this boundary
late day given the afternoon instability progged and improving
upper level dynamic from the left entrance region of an weak upper
level jet crossing western Oklahoma. The current distribution of
precipitation chances across south central Kansas still looks on
track so other than adjusting the location of the front, no major
adjustments to the previous forecast is anticipated late today and
early tonight. SPC mesoanalysis indicating better 0-6km shear late
today so at this time can not rule the chance of a few
thunderstorms near the Oklahoma border. Quarter size hail, gusty
winds and periods of heavy rainfall currently appear to be the
main hazard late today.

Convection across south central Kansas and near the Oklahoma
border after sunset will taper off towards midnight and skies are
expected to begin to clear from north to south. Lows tonight will
be cooler than the past few nights and based on expected 09z to
12z dewpoints will keep lows mainly in the 50s.

High pressure at the surface will build into western Kansas on
Friday as an upper level ridge builds into the western high plains
from the west. The highs on Friday are expected to climb only into
the mid to upper 70s given that both the NAM and GFS suggest a 3c-
6c decrease in 925mb-850mb temperature from 00z Thursday to 00z
Friday.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 222 PM CDT THU SEP 19 2013

Mostly clear skies and dry conditions are anticipated Friday night
through Sunday morning as an upper level ridge moves over the
Central Plains, mid levels of the atmosphere remain dry, and a dome
of high pressure slides southeast of the area. The only exception to
this will be the possibility of a few cumulus clouds around peak
heating. Winds will generally be from the northeast Friday night
shifting to more of a southerly direction Saturday into Sunday
morning. Meanwhile, an upper level shortwave will be moving through
the Western United States Saturday then into the Central Rockies
Sunday. Mid to upper level moisture will be on the increase during
the day Sunday allowing for a few clouds to form. This shortwave
will also help push a cold front through the area Sunday night. A
few thunderstorms will be possible along and ahead of this front
with winds shifting to more of a southerly direction behind it. Cold
air advection will be short lived with this front as winds shift
back to a southerly direction Monday night through Wednesday. Flow
aloft becomes more zonal (west to east) Monday night through Tuesday
then more of a southwest direction Wednesday as the next shortwave
digs into the Intermountain West. Mostly clear skies and dry
conditions are expected over Western Kansas during this timeframe
with lee troughing strengthening across eastern Colorado.

Seasonable temperatures are expected Saturday with highs around 80
degrees and lows Saturday and Sunday morning in the 50s. Highs are
then expected to reach into the lower 80s Sunday and Monday with mid
80s Tuesday and Wednesday. Lows are forecasted to range from the
upper 50s to mid 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1207 AM CDT FRI SEP 20 2013

VFR conditions will prevail at all TAF sites through late this
afternoon. As for winds, surface high pressure will sink slowly
southward into western Kansas today resulting in light and variable
winds through Friday evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
DDC  52  80  57  83 /   0   0   0   0
GCK  52  81  58  84 /   0   0   0  10
EHA  53  81  59  84 /   0   0   0  10
LBL  52  82  59  85 /   0   0   0  10
HYS  50  81  57  82 /   0   0   0   0
P28  53  80  56  82 /   0   0   0   0

&&

.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...JJohnson
SHORT TERM...Burgert
LONG TERM...Hovorka_42
AVIATION...JJohnson







AREA FORECAST DISCUSSION

NWS TWIN CITIES/CHANHASSEN MN

 359 AM CDT FRI SEP 20 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM CDT FRI SEP 20 2013

IT IS NO WONDER WHY MN/WI/IA SAW STRONG TO SEVERE THUNDERSTORMS ALL
DAY YESTERDAY AND LAST NIGHT. THAT IS ONE POTENT WAVE MAKING ITS WAY
ACROSS THE UPPER MISSISSIPPI RIVER VALLEY THIS MORNING. THERE ARE
100-120 METER 12-HR 500 MB HEIGHT FALLS ACROSS MN...NICE DRYING ON
THE WATER VAPOR DRIVING INTO MN...AND A 100 KT 250 MB JET OVERHEAD
AS EVIDENT BY THE 07Z WOOD LAKE PROFILER. THERE HAS BEEN STRONG
925-850 MB COLD ADVECTION SINCE 00Z LAST EVENING AND EVEN WITH CLOUD
COVER LAST EVENING...MOST OF THE FORECAST AREA IS 10-15 COOLER RIGHT
NOW THAN WE WERE 24 HOURS AGO. THE PWAT WENT FROM A TWO STANDARD
DEVIATION ABOVE NORMAL 1.54" AT 12Z YESTERDAY TO A MORE MODEST 1.22"
AT 00Z LAUNCH LAST EVENING OFF THE MPX SOUNDING. WE SHOULD BE MUCH
DRIER WITH THE LAUNCH THIS MORNING. THERE ARE A COUPLE AREAS OF
LIGHT SHOWERS THIS MORNING. THE FIRST IS NOW IN WEST CENTRAL WI OUT
AHEAD OF THE TROUGH AND THE SECOND IS NEAR THE SD/ND/MN BORDER NEAR
THE TROUGH AXIS. TODAY WILL FEATURE...LOW STRATO CU CLOUDS WITH
ISOLATED TO SCATTERED LIGHT RAIN SHOWERS AND A BREEZY NORTHWEST WIND
- TYPICAL POST FRONTAL FALL-LIKE WEATHER. CENTRAL MN SHOULD STRUGGLE
TO HIT 60 FOR A HIGH AND THE WIND WILL MAKE IT FEEL EVEN COOLER
TODAY ACROSS MN/WI. THERE IS LITTLE CHANCE OF SEEING MUCH SUN
TODAY...CEILINGS SHOULD LIFT IN THE AFTERNOON AND THE LIGHT RAIN
SHOWERS BECOME MUCH MORE SPARSE LATE IN THE DAY...BUT THE RH
TIME/HEIGHT PLOTS OFF ALMOST EVERY PIECE OF GUIDANCE KEEP LOW CLOUDS
AROUND THROUGH SUNSET. THAT BEING SAID...IF THERE IS HOPE FOR
SIGNIFICANT SUNSHINE TODAY...IT IS IN WESTERN MN. ELSEWHERE...IT
WILL LIKELY REMAIN BROKEN TO OVERCAST THROUGH THE DAY. CLEARING
TONIGHT SETS THE STAGE FOR CHILLY OVERNIGHT LOWS IN THE UPPER 30S
AND LOWER 40S. NO MENTION OF FROST IN THE FORECAST AS WE WILL LIKELY
REMAIN A FEW DEGREES TOO WARM...BUT WITH A WEAK SURFACE HIGH BUILDING
IN ACROSS WESTERN MN...SOME PATCHY FROST CAN NOT COMPLETELY BE RULED
OUT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 359 AM CDT FRI SEP 20 2013

THE LONG TERM LOOKS QUIET BUT RATHER PLEASANT AS TROUGHING TAKES
HOLD ACROSS THE WESTERN CONUS AND A PERSISTENT RIDGE REMAINS OVER
THE SOUTHEAST. THE HESITATION TO KICK OUT THE SOUTHEASTERN RIDGE
WILL TEND TO WEAKEN SHORT WAVES AS THEY EJECT EAST/NORTHEASTWARD
DURING THE PERIOD. TIMING OF THESE SYSTEMS IS ALSO UNCERTAIN WITH
EACH MODEL RUN SLOWING DOWN THEIR PROGRESSION SLIGHTLY. THIS
SPELLS A PROLONGED PERIOD OF WARM TEMPERATURES AND MAINLY DRY
WEATHER.

SURFACE HIGH PRESSURE WILL BE LOCATED OVER MINNESOTA SATURDAY AND
WISCONSIN SATURDAY NIGHT. THESE PERIODS WILL BE THE COOLEST FOR
THE NEXT 7 DAYS WITH AREAS OF FROST EXPECTED OVER WISCONSIN EARLY
SUNDAY MORNING. WESTERN MINNESOTA WILL BE IN THE RETURN FLOW
REGIME AND THUS CONSIDERABLY WARMER NEAR 50. THIS RETURN FLOW WILL
ENVELOP THE REST OF THE AREA SUNDAY AS THE HIGH PUSHES A BIT
FURTHER EAST AND THE PRESSURE GRADIENT TIGHTENS AS LOW PRESSURE
DEEPENS OVER THE PLAINS. WIND GUSTS OF 35 TO 40 MPH ARE PROBABLE IN
THE MN RIVER VALLEY. HIGHS ARE A BIT MORE UNCERTAIN GIVEN A RATHER
IMPRESSIVE GRADIENT EXPECTED ACROSS THE AREA. THERMAL RIDGING
SHOULD BE EXPANDING EASTWARD INTO AT LEAST WRN MN BY
AFTERNOON...WHICH WOULD SUPPORT HIGHS IN THE 80S. FURTHER
EAST...THESE TEMPERATURES WILL TAPER TO THE MID 60S ACROSS WI.

THE LOW WILL BE ABSORBED INTO A LARGE CANADIAN CYCLONE MONDAY.
MID LEVEL ENERGY EJECTING FROM THE SOUTHWEST WILL WEAKEN
CONSIDERABLY AND MOST MODELS FINALLY SHOW A DRY FORECAST ACROSS
THE AREA MONDAY/MONDAY NIGHT. COULD SEE A FEW LEFTOVER SHOWERS OR
SPRINKLES PASS OVERHEAD...BUT DRY BOUNDARY LAYER AIR WILL MAKE
EVEN THIS DIFFICULT. CONTINUED TO REDUCE POPS AND THE NEXT SHIFT
OR TWO MAY COMPLETELY REMOVE THEM.

A DEEP TROUGH WILL BEGIN TO DEVELOP OVER THE WESTERN CONUS DURING
THE MIDDLE OF NEXT WEEK. MERIDIONAL FLOW OVER THE CENTRAL CONUS
WILL SLOW THE EASTWARD PROGRESSION OF THIS TROUGH FROM WHAT THE
MODELS INDICATE...ALTHOUGH THEY ARE SLOWER THIS MORNING THAN
PREVIOUS RUNS. REMOVED POPS FROM TUESDAY-WEDNESDAY AND REDUCED
THEM WEDNESDAY NIGHT/THURSDAY WITH KINEMATICS AND FRONTAL
BOUNDARIES WELL OFF TO THE NORTH AND WEST OF THE AREA. AS WINDS
VEER SLIGHTLY MORE SOUTH OR SOUTHWESTERLY...DEEPER MOISTURE AND
WARMER TEMPERATURES WILL ARRIVE AND WE COULD SEE LOWS IN THE 60S
AND HIGHS IN THE 80S WEDNESDAY AND THURSDAY. HARD TO IMAGINE THESE
TEMPERATURES WILL LAST MUCH LONGER AS WE HEAD TOWARD OCTOBER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1047 PM CDT THU SEP 19 2013

STILL EXPECTING THE STRATUS DECK OVER ERN ND TO EXPAND SOUTHEAST
OVERNIGHT ACROSS THE TAF SITES...AND CAUSE CIGS TO GRADUALLY LOWER
TO MVFR /POSSIBLY EVEN IFR AT TIMES/ BETWEEN 06Z AND 12Z FRIDAY.
CONTINUE TO FAVOR THE RAP AND HRRR MODELS...WHICH BRING LOW CIGS
INTO NORTHERN-MOST SITES /KAXN AND KSTC/ BETWEEN 06Z AND
08Z...THEN EAST AND SOUTH TO THE REACH THE REMAINDER OF THE SITES
BY DAYBREAK. THEN EXPECT CIGS TO STAY BKN-OVC IN THE MVFR LEVEL
THROUGH MUCH OF THE MORNING...SHOWING IMPROVEMENT DURING THE
AFTERNOON. THE DIRECTIONAL COMPONENT OF THE WIND WILL GENERALLY
VARY FROM 280-310 DEGREES THROUGH THE PERIOD. SPEEDS AOB 10KTS
THROUGH THE NIGHT...BECOMING GUSTY /UPPER TEENS TO LOWER 20S IN
KNOTS/ AGAIN AFTER 14Z FRIDAY. WIDELY SCATTERED LIGHT RAIN SHOWERS
/VFR VSBYS/ WILL ALSO BE POSSIBLE ON FRIDAY AS THE TROUGH ROTATES
OVER...ALTHOUGH COVERAGE/PROBABILITY IS TOO LOW TO WARRANT
INCLUSION IN THE TAFS AT THIS TIME.

KMSP...

STRATUS CLOUDS WITH MVFR CIGS ARE EXPECTED AROUND 10Z...AND
POSSIBLY BELOW 1700 FT FOR A WINDOW OF TIME BETWEEN 12Z AND 18Z.
SCATTERING OUT IS THEN EXPECTED GRADUALLY THROUGHOUT THE AFTERNOON.
WINDS 280-310 DIRECTIONALLY AOA 9KTS THROUGH THE PERIOD...GUSTING
TO BETWEEN 20 AND 24 KTS AFTER 15Z FRIDAY.

/OUTLOOK FOR KMSP/
SAT...VFR. NORTHWEST WIND 5 KTS.
SUN...VFR. SOUTHEAST WIND 12-15 KTS.
MON...VFR. SOUTHEAST WIND 10-15 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...CLF
LONG TERM...BORGHOFF
AVIATION...LS







AREA FORECAST DISCUSSION

NWS ST LOUIS MO

 326 AM CDT Fri Sep 20 2013

.SHORT TERM:  (Through Tonight)
Issued at 326 AM CDT Fri Sep 20 2013

Main concern will be how quickly the rain will exit the area today.
Cold front currently extends from Kirksville to Sedalia to Nevada.
Ahead of it, there is a large band of rain with the leading edge
of the thunderstorms extending from just northeast of metro St.
Louis southwestward West Plains. This line should continue to
move east in the near term...though there will continue to be some
weakening in this line as the RAP shows the 925-850mb moisture
convergence diminishing. The cold front will continue to move
southeast today, clearing the CWA by 21Z. The main band of rain
with embedded thunderstorms will be found ahead of it, aided by
ascent from the front and the deep upper through moving across the
central CONUS. This is generally follows the latest runs of the
HRRR which shows rain slowly spreading southeast with time.

With clouds and rain today, temperatures will be much cooler than
yesterday. Some locations in south and east may not see much
diurnal recovery.

Britt

.LONG TERM: (Saturday through Wednesday)
Issued at 326 AM CDT Fri Sep 20 2013

Forecast remains dry in the long term.  Strong subsidence sets in
the wake of the upper trough as upper ridge builds in over the
region by late Sunday. Deep trough that enters the West Coast over
the weekend still shears out before it can give us any rain. Then
GFS/ECMWF both begin to amplify pattern over the CONUS by the
middle of next week with a trough over the Rockies and ridge over
the Mississippi Valley on Wednesday.

A dry airmass and light winds/mainly clear skies should allow for
some excellent radiational cooling at night. Went a few degrees
below guidance for lows over the weekend into early next week.

Britt

&&

.AVIATION:  (For the 06z TAFs through 06z Friday Night)
Issued at 1136 PM CDT Thu Sep 19 2013

A line of thunderstorms stretching from near Chicago, Illinois
through Columbia, Missouri to northeast Oklahoma will continue to
steadily march east-southeast tonight. Expect MVFR or IFR ceilings
to develop in the wake of this convection and ahead of the cold
front that stretches from central Iowa through northwest Missouri.
Initial storms and outflow will switch wind to the northwest, but
real wind shift will come with the cold front Friday morning. Some
indication by model guidance that light rain may continue Friday
morning for locations along and south of Interstate 70. This is
reasonable given the position of the upper level trof to our west.
Finally VFR conditions and clearing skies are expected by Friday
evening as dry cool air filters into the region.

Specifics for KSTL:

Wind shift to the northwest will occur shortly with outflow
boundary. Trailing line of thunderstorms should reach the terminal
between 07Z and 09Z, with light rain continuing into the daylight
hours Friday morning. Have lowered ceiling to MVFR, but can`t rule
out IFR flight conditions similar to what KIRK is observing at
this time. Cold front should move through by afternoon with
improving conditions.

CVKING

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







AREA FORECAST DISCUSSION

NWS BUFFALO NY

 411 AM EDT FRI SEP 20 2013

.SYNOPSIS...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL PROVIDE ANOTHER DAY
OF DRY WEATHER FOR MOST OF THE REGION TODAY WITH TEMPERATURES RISING
TO ABOVE NORMAL. RAIN IS EXPECTED TONIGHT INTO SATURDAY AS A COLD
FRONT MOVES EAST ACROSS THE GREAT LAKES. TEMPERATURES WILL FALL BACK
BELOW NORMAL WITH DRY CONDITIONS EXPECTED BEHIND THE COLD FRONT FOR
SUNDAY INTO MUCH OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE MID ATLANTIC COAST TODAY.
A STEADY INFLUX OF LOW LEVEL MOISTURE WILL PUSH NORTHWARD INTO
WESTERN NEW YORK ON THE WESTERN SIDE OF THE HIGH AS A WARM
FRONTAL BOUNDARY CURRENTLY STRETCHING ACROSS THE SOUTHERN GREAT
LAKES/OHIO VALLEY ADVANCES TOWARD THE REGION. UPSTREAM RADARS
SHOWING GOOD COVERAGE OF CONVECTION ASSOCIATED WITH THE WARM FRONT
BUT ALL SHORT TERM MODELS INCLUDING HRRR AND 00Z SPC SSEO RUN
DISSIPATE THIS ACTIVITY AS IT WORKS EASTWARD INTO THE RIDGE THIS
MORNING. THERE WILL BE SOME OPPORTUNITY FOR CONVECTIVE DEVELOPMENT
ACROSS FAR WESTERN NEW YORK THIS AFTERNOON AS ATMOSPHERE
DESTABILIZES...BUT FOR THE MOST PART THE DAY LOOKS DRY FOR A GOOD
PORTION OF THE AREA. A WARM DAY IN STORE WITH TEMPERATURES WITH
HIGHS IN THE UPPER 70S TO LOWER 80S...A SOLID 10 DEGREES ABOVE
NORMAL.

TONIGHT...UPPER TROUGH CURRENTLY OVER THE MANITOBA BORDER STRETCHING
DOWN THROUGH THE NORTHERN PLAINS WILL TRACK EAST AND INTO THE GREAT
LAKES. THIS WILL DRIVE A COLD FRONT TOWARD WESTERN NEW YORK LATE
TONIGHT. DEEP LAYER FORCING WILL ACCOMPANY THE FRONT...WITH PVA AND
RIGHT ENTRANCE REGION FORCING/UPPER DIFFLUENCE STACKED ABOVE THE
FRONT...GENERATING A WIDESPREAD COVERAGE OF SHOWERS AND
THUNDERSTORMS INTO WESTERN NEW YORK...ESPECIALLY AFTER 06Z. SEVERE
POTENTIAL LOOKS LIMITED WITH DIMINISHING INSTABILITY. HOWEVER WITH
THE APPROACH OF THE UPPER TROUGH...UNIDIRECTIONAL WIND PROFILES
DEVELOP WITH 0-6 KM BULK SHEAR VALUES INCREASING TO 30 TO 35
KNOTS...NOT COMPLETELY RULING OUT A FEW GUSTY THUNDERSTORMS.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
THE UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS STATES TODAY WILL
MOVE TO THE GREAT LAKES AND NORTHEASTERN STATES DURING THE WEEKEND.
THE TROUGH WILL PUSH A COLD FRONT EASTWARD ACROSS THE REGION LATE
FRIDAY NIGHT AND INTO CENTRAL NY BY LATE SATURDAY. ABUNDANT MOISTURE
WILL POOL ALONG AND AHEAD OF COLD FRONT...PROVIDED BY THE REMNANTS
OF EASTERN PACIFIC TROPICAL SYSTEMS...WITH A LINE OF THUNDERSTORMS
AND TRAILING STRATIFORM RAIN INTO SATURDAY MORNING AS THE FRONT
MOVES EAST. RAIN AMOUNTS WITH THIS SYSTEM MIGHT EXCEED AN INCH IN
SOME LOCATIONS.

REMAINING LOW LEVEL MOISTURE BEHIND THE FRONT WILL PRODUCE AREAS OF
DRIZZLE IN UPSLOPE REGIONS SATURDAY NIGHT AS AN INVERSION TRAPS
MOISTURE BELOW 800MB.  HIGH PRESSURE BUILDING ACROSS REGION ON
SUNDAY WILL BRING A SLOW CLEARING TREND THROUGH THE DAY.
TEMPERATURES WILL BE THE MID 40S TO LOW 50S SATURDAY NIGHT AND THE
HIGHS ON SUNDAY WILL ONLY BE IN THE MID 50S TO AROUND 60 UNDER
COLDER NORTHWESTERLY FLOW. NEARLY CLEAR SKIES SUNDAY NIGHT WILL
YIELD A CHILLY NIGHT WITH VALLEY FOG FORMING.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
HIGH PRESSURE MOVES INTO THE LOWER GREAT LAKES REGION NEXT
WEEK...PROVIDING DRY WEATHER ACROSS THE REGION FOR MOST IF NOT ALL
OF NEXT WEEK.  EXPECT TYPICAL EARLY FALL SEASON HIGHS AND LOWS WITH
ABUNDANT DAYTIME SUNSHINE...CLEAR SKIES OVERNIGHT AND PATCHY FOG IN
INLAND VALLEYS DURING THE EARLY MORNING HOURS.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL KEEP FINE VFR
CONDITIONS IN PLACE THROUGH THE OVERNIGHT...WITH JUST THE POTENTIAL
FOR SOME VALLEY FOG/STRATUS FOR SITES SUCH AS KJHW AND KELZ.

FOR FRIDAY...WHILE VFR WEATHER WILL PREVAIL ACROSS THE REGION...
THERE WILL BE THE RISK FOR SOME MIDDAY AND AFTERNOON CONVECTION OVER
THE FAR WESTERN COUNTIES (WEST OF GEN VALLEY).

OUTLOOK...
FRIDAY NIGHT...MVFR WITH SHOWERS AND THUNDERSTORMS BECOMING LIKELY.
SATURDAY...MVFR WITH RAIN AND THUNDERSTORMS.
SUNDAY AND MONDAY...MAINLY VFR.

&&

.MARINE...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL PROVIDE TRANQUIL
WEATHER THROUGH TODAY. EXPECT LIGHT WINDS AND MINIMAL WAVES. A COLD
FRONT WILL APPROACH THE LOWER GREAT LAKES TONIGHT INTO SATURDAY
WITH WAVES INCREASING ON THE EASTERN ENDS OF THE LAKES. SMALL CRAFT
CONDITIONS MAY BE REACHED ON THE EASTERN HALF OF LAKE ONTARIO
TONIGHT AS THE FRONT APPROACHES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA
SHORT TERM...WCH
LONG TERM...ZAFF
AVIATION...RSH/TMA
MARINE...TMA





AREA FORECAST DISCUSSION

NWS STATE COLLEGE PA

 540 AM EDT FRI SEP 20 2013

.SYNOPSIS...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL MAINTAIN
ITS GRIP ON THE REGION TODAY. A COLD FRONT WILL PUSH EAST ACROSS
THE STATE SATURDAY. AN OMEGA BLOCK AND ASSOCIATED HIGH PRES WILL
LIKELY BE PARKED OVR THE AREA THROUGH ALL OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLEAR SKIES...A CALM WIND AND INCREASING LOW LVL MOISTURE HAS
RESULTED WIDESPREAD VALLEY FOG EARLY THIS AM. MODIS 11-3.7UM SATL
IMAGERY SHOWS THE MOST EXTENSIVE LOW STRATUS/FOG HAS FORMED ACROSS THE
NORTH CENTRAL MTNS. LEANING TOWARD AN SPS RATHER THAN AN ADVISORY
TO COVER LOCALLY DENSE FOG THIS AM.

VALLEY FOG SHOULD BURN OFF BY 13Z-14Z ACROSS MOST OF THE AREA
BASED ON 3KM HRRR SFC RH AND WHAT OCCURRED YESTERDAY. HOWEVER...STRATUS
DECK...WHICH HAS WORKED INTO SOMERSET AND WARREN COUNTIES...MAY
TAKE UNTIL ALMOST NOON TO LIFT/BREAK UP INTO SCT-BKN CU FIELD.

HIGHER PWAT AIR ON WESTERN PERIPHERY OF SFC HIGH WILL BE ACROSS
WESTERN PA AND LEAD TO A MIX OF SUN AND CU THIS AFTN...WHILE DRIER
AND MAINLY SUNNY SKIES PREVAIL ACROSS THE EASTERN COUNTIES. CAN/T
RULE OUT A VERY ISOLD LATE DAY SHRA/TSRA IN THE MORE HUMID AND
MARGINALLY UNSTABLE AIR MASS ACROSS THE W MTNS. HOWEVER...UPPER
LVL RIDGING AND ASSOC WARM MID LVL TEMPS SHOULD ENSURE A DRY DAY
FOR THE VAST MAJORITY OF THE AREA.

GEFS 925TEMPS BTWN 16C-21C FROM SE TO NW SHOULD SUPPORT HIGH TEMPS
THIS AFTN IN THE M/U70S...WITH THE WARMEST TEMPS RELATIVE TO
NORMAL ACROSS THE W MTNS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
SHORT RANGE MDLS IN AGREEMENT WITH RESPECT TO TIMING OF COLD
FRONT....WHICH SHOULD ENTER THE NW MTNS LATE SAT AM AND EXIT
EASTERN PA DURING THE EVENING HRS. DEEP SOUTHERLY FLOW AND ASSOC
ATMOSPHERIC RIVER OF ANOMALOUS PWATS WILL PRECEDE APPROACHING COLD
FRONT...BRINGING A DECENT RAINFALL TO MOST OF CENTRAL PA. LATEST
SREF AND GEFS OUTPUT INDICATE A LIKELIHOOD OF RAIN TOTALS NR 1
INCH OVR MUCH OF THE AREA WITH LOCAL TOTALS ARND 2 INCHES MOST
LIKELY ACROSS THE EASTERN HALF OF THE STATE...DUE TO POSSIBLE WEAK
WAVE AND SLOWING OF FRONT SAT EVENING. MDL CAPES ARE UNIMPRESSIVE...THE
RESULT OF ABUNDANT PRE-FRONTAL CLOUD COVER. HOWEVER...WILL MAINTAIN
SLGHT CHC OF EMBEDDED TSRA.

GEFS AND SREF OUTPUT BOTH SUPPORT POPS NR 100 PCT ACROSS THE
ENTIRE AREA SATURDAY. CURRENT MDL TIMING SUGGESTS THE EASTERN
COUNTIES MAY REMAIN DRY UNTIL THE AFTN HRS...WHILE RAIN IS LIKELY
TO BEGIN BEFORE DAWN ACROSS THE NW MTNS. BACK EDGE OF THE RAIN
SHOULD ARRIVE OVR THE W MTNS ARND 21Z AND THE EASTERN COUNTIES BY
ARND MIDNIGHT.

CLOUD COVER AND RAINFALL WILL LIKELY HOLD TEMPS IN THE M/U60S SAT
ACROSS THE ALLEGHENY PLATEAU...WHILE THE SUSQ VALLEY IS LIKELY TO
GET INTO THE L/70S BEFORE THE RAIN STARTS IN THE AFTN.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
UPPER LVL TROF AND ASSOC COLD TEMPS ALOFT WILL PASS THRU PA ON
SUNDAY...RESULTING IN A GOOD DEAL OF DIURNAL CU. CAN/T RULE OUT A
FEW SPRINKLES ACROSS THE N MTNS. HOWEVER...LOW PWAT AIR MASS IS
UNLIKELY TO PRODUCE MEASURABLE RAIN IN MANY SPOTS. ENS MEAN
925TEMPS ARE SUPPORTIVE OF HIGHS FROM JUST THE U50S ACROSS THE W
MTNS...TO THE U60S IN THE SUSQ VALLEY. A RATHER TIGHT PRES
GRADIENT BTWN DEPARTING CDFRONT AND HIGH PRES OVR THE WESTERN
LAKES SHOULD RESULT IN A FAIRLY ACTIVE NW WIND ON SUNDAY...ADDING
TO THE FALL-LIKE FEEL.

FAIRLY GOOD AGREEMENT AMONG MED RANGE GUIDANCE FOR NEXT
WEEK...MOST OF WHICH INDICATE PA WILL BE UNDER RIDGE PORTION OF
OMEGA BLOCK...RESULTING IN AN EXTENDED PERIOD OF FAIR WEATHER.
GEFS 925/850 TEMPS INDICATE DAYTIME TEMPS WILL BE NEAR TO A BIT
ABOVE NORMAL. HOWEVER...DRY AIR AND PROXIMITY OF SFC HIGH WILL
LIKELY PRODUCE SOME COOL MORNINGS.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE DEPARTING TO THE EAST HAS BROUGHT LIGHT SOUTHERLY
FLOW TO CENTRAL PA...GRADUALLY INCREASING LOW LEVEL MOISTURE WITH
DEWPOINTS NOW MAINLY IN THE 50S. WITH TEMPS COOLING TO NEAR THESE
DEWPOINTS...AREAS OF FOG HAVE FORMED WITH SOME AREAS /ESP IN THE
NORTHWEST MTNS/ DROPPING TO VLIFR WITH CONDITIONS ELSEWHERE QUITE
VARIABLE. ALL TAF SITES...IF IT HASN/T BEGUN ALREADY...SHOULD
EVENTUALLY SEE RESTRICTIONS DEVELOP THAT WILL LINGER THROUGH
AROUND 14Z. RESTRICTIONS WILL LINGER THE LONGEST IN THE WEST WHERE
A LOW CLOUD DECK IS SPREADING OVER TOP OF THE FOG.

CONDITIONS WILL SLOWLY IMPROVE THROUGH MID MORNING...WITH CIGS
AND VSBYS RETURNING TO THE VFR RANGE FOR ALL BY LATE MORNING.
VFR CONDITIONS WILL THEN CONTINUE THROUGH EARLY FRIDAY NIGHT.

AN APPROACHING COLD FRONT WILL USHER IN LOWER CIGS FROM WEST TO
EAST LATE FRI NIGHT INTO SATURDAY MORNING...WITH FREQUENT SHOWERS
AND POSSIBLE THUNDERSTORMS MOVING INTO THE FAR WEST AFTER 09Z.

OUTLOOK...
SAT-SAT NIGHT...COLD FRONT CROSSES REGION. RAIN AND SCT TSTMS WILL
BRING RESTRICTIONS AREA-WIDE.

SUN...MVFR CONTINUES IN SCT SHRA/TSRA...ESP IN THE MORNING ACROSS
THE NRN MTNS...AND SE PA AIRFIELDS.

MON AND TUE...NO SIG WX.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR







AREA FORECAST DISCUSSION

NWS ABERDEEN SD

 353 AM CDT FRI SEP 20 2013

.SHORT TERM...TODAY THROUGH SUNDAY
UPPER TROUGH AXIS IS CENTERED OVER THE DAKOTAS EARLY THIS MORNING
WITH A SMALLER INDIVIDUAL SHORTWAVE/VORT MAX SPINNING ACROSS
NORTHEAST SD. ISOLATED SPRINKLES/LIGHT SHOWERS HAVE BEEN OCCURRING
OVER THE PAST SEVERAL HOURS IN ASSOCIATION WITH THIS SMALLER VORT
MAX. HRRR PICKING UP ON THIS SOMEWHAT AND SHOWS THIS ACTIVITY
MOVING OUT OF THE AREA LATER THIS MORNING AS THE SHORTWAVE EXITS.
PLENTY OF STRATUS CLOUDS WITH THIS WAVE AS WELL. SOUNDINGS ACROSS
THE CWA SUGGEST MORE SUN THAN CLOUDS ACROSS THE WESTERN CWA
THROUGH THE DAY...BUT ACROSS THE EAST...STRATUS WILL TAKE SOME
TIME TO EXIT. AND WHATEVER STRATUS DOES EXIT OR DISSIPATE WILL
LIKELY BE FILLED BY CUMULUS DEVELOPMENT BY LATE MORNING OR EARLY
AFTERNOON. TEMPS WILL BE RATHER COOL ACROSS THE EASTERN CWA TODAY
WHERE TEMPS ALOFT ARE COLDEST. HIGHS IN THE 60S CAN BE EXPECTED
HERE.

SURFACE HIGH PRESSURE CENTERS ITSELF OVER THE REGION TONIGHT INTO
SATURDAY MORNING. THIS IS A COOL AIR MASS MOVING INTO THE AREA SO
WITH CLEARING SKIES AND LIGHT WINDS OVERNIGHT...LOOKING AT A
CHILLY START TO THE MORNING ON SATURDAY. MORNING LOWS IN THE 30S
ARE FORECAST FOR MOST OF THE EASTERN CWA...WITH THE JAMES VALLEY
LIKELY FALLING INTO THE MID 30S.

WARM AIR ADVECTION RAMPS BACK UP AGAIN SATURDAY INTO SUNDAY...WITH
WARMING TEMPERATURES AND INCREASING SOUTHEAST WINDS. BREEZY/WINDY
CONDITIONS LOOK LIKELY ON SUNDAY AS THE PRESSURE GRADIENT ACROSS
THE CWA BECOMES RATHER TIGHT.


.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
THE LONG TERM SHOULD BE FAIRLY ACTIVE ACCORDING TO THE LATEST
MODELS. A SOMEWHAT PROGRESSIVE MID LEVEL FLOW IS ANTICIPATED WITH
ONE DECENT S/W TROF MOVING THROUGH SUNDAY NIGHT AND MONDAY. THIS
SHOULD BRING RAIN/THUNDER TO MUCH OF THE CWA...ALTHOUGH MOST
MODELS ARE MORE BULLISH WITH AMOUNTS OVER THE WESTERN CWA VS THE
EAST. THEN A FAIRLY DEEP TROF DIGS INTO THE WESTERN CONUS SETTING
UP SOUTHWEST FLOW ALOFT FOR THE LATTER PART OF NEXT WEEK. A
FRONTAL BOUNDARY WILL BE PARKED ACROSS THE AREA. RAIN CHANCES ARE
EXPECTED MAINLY BEHIND THE FRONT THROUGH THE PERIOD. THE MODELS DO
HAVE SOME DIFFERENCES ON THE STRENGTH OF S/W ENERGY AND SFC WAVES
RIDING THE FRONT...BUT AT THAT TIME RANGE THIS IS EXPECTED.
OVERALL TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD.


&&

.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

LOW VFR TO MVFR CLOUDS WILL RESIDE ACROSS THE REGION FOR A FEW
MORE HOURS EARLY THIS MORNING...BEFORE SKIES CLEAR OFF. A FEW RAIN
SHOWERS ARE NOTED DEVELOPING MAINLY OVER SOUTHERN/SERN NORTH
DAKOTA SLIDING DOWN INTO THE AREA...SO HAVE ADDED A VICINITY
SHOWER MENTION TO THE KABR AND KATY TERMINALS FOR A FEW HOURS
EARLY THIS MORNING.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...TDK

WEATHER.GOV/ABERDEEN






AREA FORECAST DISCUSSION

NWS MEMPHIS TN

 1222 AM CDT FRI SEP 20 2013

.UPDATE...
UPDATED FOR 06Z AVIATION DISCUSSION.

&&

.PREV DISCUSSION... /ISSUED 647 PM CDT THU SEP 19 2013/

UPDATE...

UPDATED FOR 00Z AVIATION DISCUSSION.

DISCUSSION...WATER VAPOR SATELLITE/UPPER AIR PROFILER/WSR-88D VAD
WIND PROFILE TRENDS STILL PLACE AN UPPER LEVEL RIDGE AXIS OVER THE
SOUTHEAST UNITED STATES THIS AFTERNOON. THIS IS RESULTING IN
ACROSS THE MID SOUTH WITH ISOLATED TO SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY THUS FAR LIMITED TO PORTIONS OF
CENTRAL/NORTH CENTRAL ARKANSAS AND SOUTH CENTRAL/SOUTHEAST
MISSOURI. TEMPERATURES AS OF 3 PM CDT ARE IN THE MIDDLE TO UPPER
80S AT MOST LOCATIONS. SHOWER AND THUNDERSTORM CHANCES ASSOCIATED
WITH AN APPROACHING COLD FRONT IS THE MAIN FORECAST CHALLENGE IN
THIS AFTERNOON/S FORECAST.

SHORT TERM MODELS INCLUDING THE 3KM HRRR INDICATE SHOWERS AND
THUNDERSTORMS LOCATED OVER PORTIONS OF ARKANSAS AND SOUTHERN
MISSOURI WILL WEAKEN AND DIMINISH WITH THE LOSS OF DAYTIME HEATING
THIS EVENING. THERE IS A POSSIBILITY THAT SOME OF THIS ACTIVITY
MAY REACH AREAS WEST OF THE MISSISSIPPI RIVER THIS EVENING AND
LEFT ISOLATED SHOWERS AND THUNDERSTORMS IN THE FORECAST. HOWEVER...THINK
BETTER SHOWER/THUNDERSTORM CHANCES WILL HOLD OFF UNTIL LATER
TONIGHT AS THE RIDGE MOVES FURTHER EAST AND MID LEVEL HEIGHT FALLS
WEAKEN SLIGHTLY.

A COLD FRONT CURRENTLY LOCATED OVER THE UPPER MIDWEST AND CENTRAL
PLAINS THIS AFTERNOON WILL DROP INTO THE LOWER MISSISSIPPI VALLEY
ON FRIDAY. MODEST MID LEVEL HEIGHT FALLS AND INSTABILITY WILL
ALLOW FOR SHOWERS AND THUNDERSTORMS TO OVERSPREAD THE MID SOUTH
MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER FRIDAY MORNING AND
SPREAD EAST TO THE REMAINDER OF THE FORECAST AREA FRIDAY AFTERNOON
INTO FRIDAY NIGHT.

NOT OVERLY IMPRESSED WITH STRONG/SEVERE THUNDERSTORM POTENTIAL AS
OVERALL SHEAR...INSTABILITY...AND FORCING WILL REMAIN ON THE WEAK
SIDE. LATER SHIFTS WILL MONITOR SHORT TERM TRENDS AND ADD STRONG
THUNDERSTORM MENTION IN THE HAZARDOUS WEATHER OUTLOOK IF
CONDITIONS BECOME MORE FAVORABLE AS THE FRONT APPROACHES. OVERALL
RAINFALL AMOUNTS THROUGH FRIDAY NIGHT MAY AVERAGE AROUND ONE HALF
INCH WITH LOCALIZED AMOUNTS UP TO PERHAPS 1.5-2 INCHES ALONG AND
WEST OF THE MISSISSIPPI RIVER...AND LESSER AMOUNTS TOWARDS THE
TENNESSEE RIVER. THE 12Z GFS HAS REMAINED ON THE QUICKER SIDE OF
MODEL SOLUTIONS TODAY AND LEANED FORECAST TOWARDS THE WRF/ECMWF
WHICH SUGGEST FRONTAL PASSAGE FRIDAY AFTERNOON/FRIDAY NIGHT.

LINGERING SHOWERS AND THUNDERSTORMS MAY PERSIST ON SATURDAY...ESPECIALLY
ACROSS NORTHEAST MISSISSIPPI AS THE FRONT SLOWS BEFORE DEPARTING
THE FORECAST AREA BY SATURDAY NIGHT. COOLER AND DRIER AIR WILL
FILTER IN BEHIND THE FRONT RESULTING IN A PERIOD OF MAINLY RAIN
FREE WEATHER ACROSS THE MID SOUTH THROUGH AT LEAST EARLY NEXT
WEEK AND TEMPERATURES AVERAGING NEAR NORMAL FOR SEPTEMBER. 12Z
GFS/ECMWF INDICATE SOME MODEL RUN TO RUN CONTINUITY ISSUES WITH
THE APPROACH OF AN UPPER LEVEL TROUGH OVER THE
PLAINS/MIDWEST...A BUILDING RIDGE OVER THE LOWER MISSISSIPPI
VALLEY AND THE POTENTIAL FOR WEAK SOUTHERLY LOW LEVEL RETURN FLOW
FROM THE GULF OF MEXICO PRODUCING SHOWERS AND THUNDERSTORMS. WILL
KEEP REMAINDER OF FORECAST NEXT WEEK DRY FOR NOW UNTIL MODELS
COME INTO BETTER AGREEMENT.

CJC

&&

.AVIATION...06Z TAF CYCLE

VFR CONDS WILL PREVAIL THROUGH TOMORROW MORNING AND WINDS WILL
REMAIN 5-9 KTS PREDOMINANTLY FROM THE SOUTH OVERNIGHT. TIMING OF
SHOWERS AHEAD OF AN APPROACHING COLD FRONT TOMORROW IS THE BIGGEST
CHALLENGE RIGHT NOW. HAVE DECIDED TO INTRODUCE VCSH AT 14Z AT
MEM...MKL...AND JBR WITH TUP FOLLOWING AROUND 16Z. WIDESPREAD RAIN
AND THUNDERSTORMS SHOULD BECOME PREVAILING BY 18Z AT ALL TAF SITES
AND CONTINUE THROUGH THE END OF THE TAF CYCLE AS THE COLD FRONT
MOVES THROUGH THE REGION. MVFR/IFR CONDITIONS WILL DEVELOP
THROUGHOUT THE AFTERNOON AT TIMES DUE TO VSBYS/CIGS FROM MODERATE
RAIN. EXPECT WINDS TO SHIFT NORTHERLY BY THE END OF THE TAF CYCLE.

AC3/JAB

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  67  81  60  80 /  70  40   0   0
MKL  65  78  54  79 /  70  30  10   0
JBR  61  78  53  78 /  60  10   0   0
TUP  68  81  60  80 /  90  70  10   0

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

$$









AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 907 AM CDT FRI SEP 20 2013

.DISCUSSION...
358 AM CDT

FORECAST CONCERNS ARE MAINLY FOCUSED ON THE NEAR TERM TODAY...AS  A
COLD FRONT PUSHES STEADILY EAST ACROSS THE FORECAST AREA. SPOTTY
PRECIP WILL END WITH THE PASSAGE OF THE FRONT...WITH BREEZY...DRY AN
COOLER WEATHER ARRIVING AS WE HEAD INTO THE WEEKEND.

SURFACE LOW PRESSURE WAS CONSOLIDATING NORTH OF LAKE SUPERIOR EARLY
THIS MORNING...WITH A COLD FRONT TRAILING SOUTHWARD ACROSS WISCONSIN
AND INTO FAR EASTERN IOWA AT 08Z. RELATIVELY COMPLEX UPPER PATTERN
WAS EVIDENT FROM RADAR/WATER VAPOR IMAGERY...WITH SEVERAL SMALLER
SCALE CIRCULATIONS ROTATING THROUGH BASE OF UPPER TROUGH PROPAGATING
EAST ACROSS THE UPPER MIDWEST. AREA OF THUNDERSTORMS WHICH HAD MOVED
INTO THE FORECAST AREA LATE LAST HAD DECREASED IN COVERAGE IN THE
WAKE OF AN MCV NOTED LIFTING ACROSS SOUTHEAST WISCONSIN AND WITH
STABILIZATION OF THE NOCTURNAL BOUNDARY LAYER. A FEW SCATTERED
STORMS CONTINUED FROM NEAR KALAMAZOO MICHIGAN TO NEAR DANVILLE AND
ST LOUIS...WHERE SPC/RAP ANALYSIS INDICATES WESTERN PERIPHERY OF
1000-2000 J/KG MUCAPE AXIS.  FARTHER WEST...AN AREA OF WEAKER
SHOWERS/LIGHT RAIN WAS NOTED ALONG THE LOW LEVEL FRONTAL BOUNDARY.
HIGH-RES GUIDANCE INDICATES THE CLUSTER OF SHOWERS AND THUNDERSTORMS
IN THE ST LOUIS/DOWNSTATE IL AREA WILL LIFT NORTHEAST THROUGH THIS
MORNING...AFFECTING MAINLY OUR SOUTHEAST COUNTIES. SCATTERED SHOWERS
ARE EXPECTED ELSEWHERE...ENDING WITH COLD FROPA LATER THIS MORNING
ACROSS NORTH CENTRAL ILLINOIS AND BY EARLY AFTERNOON ACROSS
NORTHEAST IL. FORECAST SOUNDINGS DEPICT SUBSTANTIAL DRYING
DEVELOPING IN THE 850-500 MB LAYER BEHIND THE COLD FRONT...WHICH IS
EVENTUALLY PROGGED TO CLEAR THE SOUTHEAST PART OF THE CWA VERY LATE
THIS AFTERNOON/EARLY THIS EVENING. NOT EXPECTING A LARGE TEMP SPREAD
DESPITE COLD FROPA ACROSS THE CWA TODAY...AS CLOUDS WILL HELP LIMIT
READINGS AHEAD OF THE FRONT.

UPPER TROUGH CONTINUES TO DEEPEN OVERHEAD AS IT MOVES SLOWLY EAST OF
THE AREA LATER TONIGHT AND SATURDAY. STRONG COOL ADVECTION DEVELOPS
AS WINDS SHIFT NORTH-NORTHWEST DURING THE PERIOD...WITH MODEL 850 MB
TEMPS FALLING TO AROUND +4C ON SATURDAY. THIS SHOULD LIMIT TEMPS
GENERALLY TO THE MID-UPPER 60S THROUGH THE WEEKEND DESPITE A GOOD
DEAL OF SUNSHINE...WITH SLIGHTLY COOLER TEMPS NEAR LAKE MICHIGAN
SUNDAY AS WINDS TURN ONSHORE FROM THE NORTHEAST. OVERNIGHT TEMPS
WILL COOL OFF CONSIDERABLY AS WELL...ESPECIALLY SUNDAY NIGHT AS THE
SURFACE HIGH PRESSURE RIDGE AXIS SPREADS INTO WISCONSIN AND ILLINOIS
AND ALLOWS FOR STRONG RADIATIONAL COOLING. HAVE UNDERCUT GUIDANCE IN
OUR TYPICALLY COOLER LOCATIONS SUNDAY MORNING...WITH SOME UPPER 30S
LIKELY WEST OF THE FOX RIVER VALLEY IN NORTH CENTRAL IL. COULD SEE
SOME LAKE EFFECT CLOUDS ACROSS NORTHEAST ILLINOIS/NORTHWEST INDIANA
SUNDAY MORNING AS LOW LEVEL WINDS BECOME NORTH-NORTHEAST.

LOOKS LIKE A DRY PERIOD WITH A MODERATION IN TEMPERATURES INTO NEXT
WEEK...AS HIGHLY AMPLIFIED UPPER PATTERN SLOWLY SHIFTS EAST. THIS
BRINGS UPPER RIDGE ACROSS THE AREA INTO MONDAY WITH THE SURFACE HIGH
DRIFTING OFF TO THE EAST. LONGER RANGE GUIDANCE INDICATES A SHORT
WAVE PUSHING INTO THE RIDGE ACROSS THE AREA TUESDAY...BUT WITH
LITTLE MOISTURE RETURN THANKS TO SOUTHEAST LOW LEVEL WINDS WEST OF
THE AFOREMENTIONED SURFACE HIGH. ECMWF/GFS BOTH SIMILAR IN
RE-BUILDING UPPER RIDGE ACROSS THE AREA IN THE WAKE OF THE SHORT
WAVE BY MID-WEEK. THIS WOULD SUPPORT TEMPS RISING BACK THROUGH THE

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* MVFR CIGS ARND 1000-1400FT AGL...SLOWLY LIFTING AFT 16Z.
* WEST WINDS ARND 10-14KT WITH GUSTS INCREASING TO 20KT AFT 16Z.
* WINDS SLOWLY TURNING NW/N AFT 23Z.


BEACHLER

//DISCUSSION...UPDATED 12Z...

LOW MVFR CIGS NOW WIDESPREAD ACROSS THE AREA WITH SOME PATCHY IFR
CIGS. CONTINUE TO EXPECT MAINLY LOW MVFR FOR PREVAILING CIGS BUT
SOME IFR CIGS OVER THE NEXT FEW HOURS WILL BE POSSIBLE. AS A COLD
FRONT MOVES ACROSS THE AREA LATER THIS MORNING...CIGS WILL LIFT
THROUGH MVFR AND SCATTER OUT BY LATE MORNING. ADDITIONAL SHOWER
DEVELOPMENT WILL BE POSSIBLE ALONG/AHEAD OF THIS FRONT THROUGH MID
MORNING BUT BULK OF THE PRECIP MAY END UP SOUTHEAST OF MDW
AFFECTING MAINLY GYY THROUGH LATE MORNING.

WEST SOUTHWEST WINDS AROUND 10KT WILL TURN MORE WESTERLY WITH THE
COLD FRONT AND BEGIN TO GUST BY LATE MORNING WITH GUSTS IN THE
18-20KT RANGE POSSIBLE THROUGH SUNSET. WINDS WILL TURN MORE
NORTHWEST THIS EVENING AS SPEEDS DIMINISH UNDER 10KTS. CMS

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE IN MVFR CIGS THRU 16Z...MEDIUM CONFIDENCE IN
  PRECISE TIMING OF IMPROVING CIGS.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN TIMING OF WINDS TURNING NW/N.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...

* SATURDAY NIGHT...MVFR CIGS POSSIBLE.
* SUNDAY THROUGH THURSDAY...DRY/VFR.

&&

.MARINE...

310 AM...LOW PRESSURE OVER ONTARIO WILL MOVE NORTHEAST TODAY AND
TONIGHT AS IT DEEPENS WITH A TRAILING COLD FRONT MOVING ACROSS
LAKE MICHIGAN LATER THIS MORNING...TURNING WINDS WESTERLY. AS
COLDER AIR SPREADS ACROSS THE REGION THIS EVENING...WINDS WILL
TURN NORTHWESTERLY AND INCREASE IN SPEED WITH A SHORT DURATION OF
30 KTS POSSIBLE. SPEEDS WILL RELAX BACK INTO THE 15-25KT RANGE
OVERNIGHT INTO SATURDAY MORNING AND THEN DIMINISH FURTHER SATURDAY
NIGHT INTO SUNDAY MORNING AS A LARGE RIDGE OF HIGH PRESSURE SLOWLY
PASSES ACROSS THE LAKES REGION SUNDAY AND SUNDAY NIGHT. THIS HIGH
IS EXPECTED TO REMAIN OVER NEW ENGLAND...MID ATLANTIC AND EASTERN
LAKES INTO THE MIDDLE OF NEXT WEEK...ALLOWING FOR SOUTHEAST TO
SOUTHERLY FLOW OVER THE LAKE FROM SUNDAY NIGHT THROUGH THURSDAY.
CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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  [top]

Area Forecast Discussion
National Weather Service Lincoln IL
859 AM CDT Fri Sep 20 2013

.DISCUSSION...
ISSUED 859 AM CDT Fri Sep 20 2013

14z/9am surface analysis shows cold front along the Illinois
River...with scattered light showers ahead of it across much of
the KILX CWA. Based on speed of front and current stability
parameters...think threat for thunder is over for the western half
of the area. Further east, HRRR suggests some re-development
across east-central and southeast Illinois during the afternoon.
Have made a quick update to the forecast to lower POPs and drop
thunder mention along and west of I-55. Will maintain likely POPs
for showers and thunderstorms further east, mainly along and east
of I-57. Zone update has already been sent.

Barnes
&&

.AVIATION...
ISSUED 615 AM CDT Fri Sep 20 2013

Cold front just to our west will move across the TAF sites this
morning into early this afternoon with MVFR and local IFR cigs
in rain and fog. As the front progresses off to our east this
afternoon, conditions are expected to improve to VFR across
PIA and SPI first, and then over the remainder of the area by
20z. Surface winds this morning just ahead of the front will
be from a S-SW direction at 5 to 10 kts. Based on the current
movement of the front, it appears winds will switch into the
W-NW at PIA and SPI around 15z...and between 18z-20z over in CMI.
Rain chances will decrease from west to east starting later
this morning with DEC and CMI possibly seeing the rain linger
into late this morning into early this afternoon.

Smith
&&

.PREV DISCUSSION...
ISSUED 322 AM CDT Fri Sep 20 2013
Deep upper trof moving across the Northern Plains and into the
Great Lake region...with the associated sfc low centered just
north of Lake Superior. Cold front draped through WI IA MO and
into the Southern Plains...lingering to the west along the Miss
River Valley this morning. Prefrontal showers and thunderstorms
from last night lingering in the east...weakened considerably in
the absence of an abundance of instability. First and main issue
for the forecast is the recharging of the atmosphere ahead of the
boundary in the warm sector this morning and the chances for
refire in the afternoon in the southeastern CWA. Beyond that,
Midwest gets into another dry period with heat building back into
the western CONUS and spreading into Central Illinois.

SHORT TERM...Today and tomorrow...
Scattered showers and thunderstorms throughout the day with the
best chances in the east this morning with remnant activity from
the overnight hours. Cold front still to the west will have the
chance to refire this afternoon. Exact location of the showers and
thunderstorms, as well as the strength, will be entirely dependent
on the speed of the advancing front, and any pockets of sunshine
that may enhance sfc based instability. At this point, however,
the front is moving through quickly and the precip may end up
wrapping up even sooner than midnight in the southeast. Cooler
temps tonight...somewhat inhibited by cloud cover anticipated.
Concern remains that more rapid clearing may result in a needed
adjustment. Tomorrow begins an extended dry period with sunny
skies and max temps in the lower 70s...light northerly winds as
high pressure begins to build back into the region.

LONG TERM...Sunday through Thursday...
Milder weather and dry through the extended. High pressure
dominates the eastern half of the country and temperatures remain
milder and closer to normal at first...with heat slowly building
again under a thermal ridge in the southwestern US. With
southwesterly flow kicking in next week Tues, the extended could
see some warmer temps as time draws nearer should the pattern
persist. Guidance is starting to respond and climb into the upper
70s/near 80 by mid week.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








AREA FORECAST DISCUSSION

NWS QUAD CITIES IA IL

 957 AM CDT FRI SEP 20 2013

.UPDATE...
ISSUED AT 952 AM CDT FRI SEP 20 2013

CLOUD COVER IS PERSISTING LONGER THAN PREVIOUSLY THOUGHT. BASED ON
SATELLITE TRENDS...THICK HIGH CLOUDS SHOULD PERSIST FOR A MAJORITY
OF THE DAY. THE HIGH CLOUDS SHOULD SLOWLY THIN THIS AFTERNOON
ALLOWING MORE SUN TO BE SEEN.                ..08..

&&

.SYNOPSIS...
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN AREA OF SHOWERS AND THUNDERSTORMS HAS PUSHED TO EAST OF THE
DVN CWA THIS MORNING AHEAD OF THE PREFRONTAL TROUGH OVER EASTERN
IOWA AND THE COLD FRONT STRETCHES FROM CENTRAL LAKE SUPERIOR
SOUTHWARD THROUGH SOUTHEASTERN MINNESOTA AND CENTRAL IOWA AT THIS
TIME. SCATTERED SHOWERS AND LOW CEILINGS HAVE DEVELOPED ALONG THE
PREFRONTAL TROUGH THIS MORNING ASSOCIATED WITH THE CONVERGENCE ALONG
IT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN FORECASTS CONCERNS THIS MORNING WILL BE THE SCATTERED
SHOWERS ALONG THE PREFRONTAL TROUGH AND THE LOW CEILINGS.

THE MAIN AREA OF PRECIPITATION HAS MOVED INTO EASTERN ILLINOIS EARLY
THIS MORNING WITH A WEAK AREA OF SHOWERS AND LOW CEILINGS ALONG THE
PREFRONTAL TROUGH. THE 13 KM RAP HAD STRONG CONVERGENCE ALONG THIS
FEATURE EARLY THIS MORNING AND SHOWS THE CONVERGENCE WEAKENING
THROUGH 12 UTC AS BOUNDARY SHIFTS EASTWARD. THE THREAT OF SHOWERS
FROM THIS FEATURE SHOULD QUICKLY DIMINISH BY 12 UTC. THE COLD FRONT
WILL EXIT INTO CENTRAL ILLINOIS BY 15 UTC WITH STRONG COLD ADVECTION
USHERING IN MUCH COOLER AIR THAN WE HAVE EXPERIENCED OVER THE PAST
48 HOURS AND CLOSER TO NORMAL HIGH TEMPERATURES FOR MID SEPTEMBER.

CLOUDS WILL CLEAR QUICKLY THROUGH THE DAY ON FRIDAY AS DRIER AIR
MOVES INTO THE REGION. HOWEVER THERE IS SOME CONCERN THAT THE
STRATUS LAYER CURRENTLY OVER THE EASTERN DAKOTAS WILL MOVE
SOUTHEASTWARD AND INTO THE REGION FRIDAY NIGHT INTO SATURDAY
MORNING. MODELS CONTINUE TO SUGGEST THAT THE CLOUDS WILL DISSIPATE
SO WILL LEAVE THE FORECAST CLEAR OVERNIGHT. THIS PLAYS DIRECTLY INTO
THE TEMPERATURE FORECAST FOR SATURDAY MORNING AND HAVE NOT MADE ANY
CHANGES TO THE PREVIOUS FORECAST FOR LOW TEMPERATURES IN THE MID TO
UPPER 40S. IF STRATUS DOES MOVE INTO THE REGION LOW TEMPERATURES ON
SATURDAY MORNING MAY BE WARMER THAN CURRENTLY FORECAST.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 327 AM CDT FRI SEP 20 2013

NEARLY IDEAL OUTDOOR FALL WEATHER WILL GRACE THE EXTENDED FORECAST
EACH DAY. SURFACE HIGH PRESSURE OVER THE GREAT LAKES WILL DOMINATE
THE WEATHER THROUGH THE NEXT 4 DAYS...WITH A DRY FROPA
TUESDAY...FOLLOWED BY ANOTHER PLEASANT HIGH PRESSURE SYSTEM. THOSE
WITH HOPE FOR MORE RAIN WILL HAVE TO WAIT ON A SINGLE COLD FROPA
EVENT WHICH IS FORECAST BY THE GFS AND ECMWF TO OCCUR AROUND FRIDAY
NIGHT BEYOND OUR CURRENT DAY 7.  THE TUESDAY TROF PASSAGE...SHOULD
BE MOISTURE STARVED...AND MAY ONLY BRIEFLY INCREASE HIGH LEVEL CLOUD
COVER.

LARGE DIURNAL SPREADS ARE FORECAST UNDER THE HIGH PRESSURE FOR
SATURDAY THROUGH MONDAY...WITH HIGHS IN THE MID 60S TO LOWER 70S AND
LOWS QUITE COOL...IN THE LOWER TO UPPER 40S IN GENERAL. THIS
TEMPERATURE RANGE REPRESENTS READINGS A FEW DEGREES BELOW CLIMATE
NORMALS...AND IS ONLY SIGNIFICANT IN COMPARISON TO OUR RECENT RECORD
WARMTH AND HUMIDITY. BEYOND MONDAY...MODEL BLENDS CONTINUE TO
INDICATE MODERATION...HOWEVER...I AM UNCERTAIN THAT THIS IS ACTUALLY
GOING TO OCCUR GIVEN OUR POTENTIAL FOR HAVING SOUTHEAST SURFACE FLOW
UNDER THE BUILDING UPPER RIDGE OF HIGH PRESSURE. THIS TRAJECTORY
COULD KEEP THE WIDE DIURNAL TEMPERATURE RANGES GOING...ALONG WITH
TEMPERATURES CLOSE TO NORMAL. WILL PASS THIS CONCERN ON THE THE NEXT
SHIFT WHICH SHOULD BE ABLE TO MORE FORMALLY PLACE THIS INTO THE
FORECAST BLEND.
ERVIN

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 632 AM CDT FRI SEP 20 2013

A STRONG COLD FRONT IS CROSSING THE MISSISSIPPI RIVER ATTM...AND
MOVING INTO WESTERN ILLINOIS. IFR TO MVFR CEILINGS ARE CURRENTLY
IN PLACE AT KBRL AND KMLI WITH VFR CEILINGS AT KCID AND KDBQ.
CEILINGS WILL SLOWLY LIFT AT KBRL AND KMLI AND BECOME VFR AROUND
15 UTC. CONDITIONS WILL REMAIN VFR THROUGH THE PERIOD AS DRY AIR
OVERSPREADS THE REGION. CONFIDENCE IS LOW THAT STRATUS CURRENTLY
ACROSS THE NORTHERN PLAINS WILL MOVE INTO THE REGION TOWARD THE END
OF THE TAF PERIOD. WEST TO NORTHWESTERLY WINDS WILL INCREASE
DURING THE MID MORNING HOURS WITH WINDS OF 10 TO 15 KNOTS GUSTING
TO 20 TO 22 KNOTS AT ALL TAF SITES. THE WINDS WILL SUBSIDE BY 00
UTC.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...08
SYNOPSIS...DC
SHORT TERM...DC
LONG TERM...ERVIN
AVIATION...DC






AREA FORECAST DISCUSSION

NWS QUAD CITIES IA IL

 646 AM CDT FRI SEP 20 2013

.SYNOPSIS...
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN AREA OF SHOWERS AND THUNDERSTORMS HAS PUSHED TO EAST OF THE
DVN CWA THIS MORNING AHEAD OF THE PREFRONTAL TROUGH OVER EASTERN
IOWA AND THE COLD FRONT STRETCHES FROM CENTRAL LAKE SUPERIOR
SOUTHWARD THROUGH SOUTHEASTERN MINNESOTA AND CENTRAL IOWA AT THIS
TIME. SCATTERED SHOWERS AND LOW CEILINGS HAVE DEVELOPED ALONG THE
PREFRONTAL TROUGH THIS MORNING ASSOCIATED WITH THE CONVERGENCE ALONG
IT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN FORECASTS CONCERNS THIS MORNING WILL BE THE SCATTERED
SHOWERS ALONG THE PREFRONTAL TROUGH AND THE LOW CEILINGS.

THE MAIN AREA OF PRECIPITATION HAS MOVED INTO EASTERN ILLINOIS EARLY
THIS MORNING WITH A WEAK AREA OF SHOWERS AND LOW CEILINGS ALONG THE
PREFRONTAL TROUGH. THE 13 KM RAP HAD STRONG CONVERGENCE ALONG THIS
FEATURE EARLY THIS MORNING AND SHOWS THE CONVERGENCE WEAKENING
THROUGH 12 UTC AS BOUNDARY SHIFTS EASTWARD. THE THREAT OF SHOWERS
FROM THIS FEATURE SHOULD QUICKLY DIMINISH BY 12 UTC. THE COLD FRONT
WILL EXIT INTO CENTRAL ILLINOIS BY 15 UTC WITH STRONG COLD ADVECTION
USHERING IN MUCH COOLER AIR THAN WE HAVE EXPERIENCED OVER THE PAST
48 HOURS AND CLOSER TO NORMAL HIGH TEMPERATURES FOR MID SEPTEMBER.

CLOUDS WILL CLEAR QUICKLY THROUGH THE DAY ON FRIDAY AS DRIER AIR
MOVES INTO THE REGION. HOWEVER THERE IS SOME CONCERN THAT THE
STRATUS LAYER CURRENTLY OVER THE EASTERN DAKOTAS WILL MOVE
SOUTHEASTWARD AND INTO THE REGION FRIDAY NIGHT INTO SATURDAY
MORNING. MODELS CONTINUE TO SUGGEST THAT THE CLOUDS WILL DISSIPATE
SO WILL LEAVE THE FORECAST CLEAR OVERNIGHT. THIS PLAYS DIRECTLY INTO
THE TEMPERATURE FORECAST FOR SATURDAY MORNING AND HAVE NOT MADE ANY
CHANGES TO THE PREVIOUS FORECAST FOR LOW TEMPERATURES IN THE MID TO
UPPER 40S. IF STRATUS DOES MOVE INTO THE REGION LOW TEMPERATURES ON
SATURDAY MORNING MAY BE WARMER THAN CURRENTLY FORECAST.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 327 AM CDT FRI SEP 20 2013

NEARLY IDEAL OUTDOOR FALL WEATHER WILL GRACE THE EXTENDED FORECAST
EACH DAY. SURFACE HIGH PRESSURE OVER THE GREAT LAKES WILL DOMINATE
THE WEATHER THROUGH THE NEXT 4 DAYS...WITH A DRY FROPA
TUESDAY...FOLLOWED BY ANOTHER PLEASANT HIGH PRESSURE SYSTEM. THOSE
WITH HOPE FOR MORE RAIN WILL HAVE TO WAIT ON A SINGLE COLD FROPA
EVENT WHICH IS FORECAST BY THE GFS AND ECMWF TO OCCUR AROUND FRIDAY
NIGHT BEYOND OUR CURRENT DAY 7.  THE TUESDAY TROF PASSAGE...SHOULD
BE MOISTURE STARVED...AND MAY ONLY BRIEFLY INCREASE HIGH LEVEL CLOUD
COVER.

LARGE DIURNAL SPREADS ARE FORECAST UNDER THE HIGH PRESSURE FOR
SATURDAY THROUGH MONDAY...WITH HIGHS IN THE MID 60S TO LOWER 70S AND
LOWS QUITE COOL...IN THE LOWER TO UPPER 40S IN GENERAL. THIS
TEMPERATURE RANGE REPRESENTS READINGS A FEW DEGREES BELOW CLIMATE
NORMALS...AND IS ONLY SIGNIFICANT IN COMPARISON TO OUR RECENT RECORD
WARMTH AND HUMIDITY. BEYOND MONDAY...MODEL BLENDS CONTINUE TO
INDICATE MODERATION...HOWEVER...I AM UNCERTAIN THAT THIS IS ACTUALLY
GOING TO OCCUR GIVEN OUR POTENTIAL FOR HAVING SOUTHEAST SURFACE FLOW
UNDER THE BUILDING UPPER RIDGE OF HIGH PRESSURE. THIS TRAJECTORY
COULD KEEP THE WIDE DIURNAL TEMPERATURE RANGES GOING...ALONG WITH
TEMPERATURES CLOSE TO NORMAL. WILL PASS THIS CONCERN ON THE THE NEXT
SHIFT WHICH SHOULD BE ABLE TO MORE FORMALLY PLACE THIS INTO THE
FORECAST BLEND.
ERVIN

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 632 AM CDT FRI SEP 20 2013

A STRONG COLD FRONT IS CROSSING THE MISSISSIPPI RIVER ATTM...AND
MOVING INTO WESTERN ILLINOIS. IFR TO MVFR CEILINGS ARE CURRENTLY
IN PLACE AT KBRL AND KMLI WITH VFR CEILINGS AT KCID AND KDBQ.
CEILINGS WILL SLOWLY LIFT AT KBRL AND KMLI AND BECOME VFR AROUND
15 UTC. CONDITIONS WILL REMAIN VFR THROUGH THE PERIOD AS DRY AIR
OVERSPREADS THE REGION. CONFIDENCE IS LOW THAT STRATUS CURRENTLY
ACROSS THE NORTHERN PLAINS WILL MOVE INTO THE REGION TOWARD THE END
OF THE TAF PERIOD. WEST TO NORTHWESTERLY WINDS WILL INCREASE
DURING THE MID MORNING HOURS WITH WINDS OF 10 TO 15 KNOTS GUSTING
TO 20 TO 22 KNOTS AT ALL TAF SITES. THE WINDS WILL SUBSIDE BY 00
UTC.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...DC
SHORT TERM...DC
LONG TERM...ERVIN
AVIATION...DC







AREA FORECAST DISCUSSION

NWS GOODLAND KS

 522 AM MDT FRI SEP 20 2013

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 323 AM MDT FRI SEP 20 2013

INITIAL FORECAST CONCERN WILL BE TEMPERATURES THROUGH THE WEEKEND
...WINDS THROUGH THE WEEKEND...ESPECIALLY ON SUNDAY...WITH THE LAST
PROBLEM THE NEXT CHANCE FOR PRECIPITATION AT THE BEGINNING OF NEXT
WEEK. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH
AMERICA. OVER THE LAST 24 HOURS THE FLOW FROM THE CENTRAL PACIFIC
INTO NORTH AMERICA HAS AMPLIFIED. AT LOW LEVELS TWO DIFFERENT COLD
FRONTS HAVE BROUGHT IN A DRIER AND COOLER AIR MASS INTO THE AREA.

AT JET LEVEL...THE SREF FOLLOWED BY THE GFS WAS DOING THE BEST. AT
MID LEVELS...THE NAM WAS DOING A LITTLE BETTER THAN THE GFS...UKMET
AND CANADIAN. THE RUC FOLLOWED BY THE SREF AND THE NAM/ECMWF WAS
DOING THE BEST ON THE SURFACE WIND AND PRESSURE FIELD. THE GFS
FOLLOWED BY THE UKMET THEN SREF/NAM DID THE BEST ON THE LOW LEVEL
THERMAL FIELD.

TODAY/TONIGHT...WEAK SHOWERS AND THUNDERSTORMS HAVE POPPED NEAR THE
SOUTHERN AND WESTERN END OF THE FORECAST AREA. MODELS DO SHOW A RIGHT
REAR QUADRANT OF THE JET HANGING AROUND THROUGH THE MORNING AND IT
WILL BE ON TOP OF A WEAK MID LEVEL BAROCLINIC ZONE NEAR 700 MB.
WEAK FRONTOGENESIS IS IN THIS LAYER AS WELL WITH FAVORABLE THETA-E
LAPSE RATES. BASED ON LATEST TRENDS/MODEL DATA...WILL INCLUDE A
MENTION OF SPRINKLES...MOSTLY IN THE SOUTHERN HALF THROUGH MID
MORNING.

IN THE NORTHERN TIER OF COUNTIES...LACK OF CLOUD COVER HAS
ALLOWED TEMPERATURE/DEWPOINT SPREADS TO BE VERY SMALL. HAVE ALREADY
SEEN PATCHY FOG IN SOME LOCATIONS. WHERE PRECIPITATION AND CLOUD
COVER ARE NOT EXPECTED...WILL PUT IN A MENTION OF PATCHY FOG ALSO
THROUGH MID MORNING. AT THIS TIME IT LOOKS LIKE CLOUD COVER WILL
DECREASE BY LATE MORNING. BASED ON TEMPERATURE BIASES AND CHANGE
OVER THE LAST 24 HOURS COMBINED WITH WHAT HAS BEEN DOING BEST ON
MAXES...MADE SOME ADJUSTMENTS UP FROM THE PREVIOUS FORECAST FOR THE
HIGH TEMPERATURES. MINS WILL BE WARMER TONIGHT DUE TO STRONGER
WINDS.

SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING TO
THE EAST WITH STRONG CROSS MOUNTAIN FLOW DEVELOPING. DURING THE LAST
HALF OF THE NIGHT THE MODELS SHOW THAT A LEFT FRONT QUADRANT
APPROACHES FROM THE SOUTH. THIS COULD SPREAD SOME HIGHER LEVEL CLOUDS
INTO THE AREA...ESPECIALLY IN THE SOUTHERN HALF. DUE TO A DRY AND
WELL MIXED AIR MASS...WILL KEEP THIS PERIOD DRY.

AS THE RESULT OF THE STRONG CROSS MOUNTAIN AND INCOMING UPPER
TROUGH MOVING INTO THE GREAT BASIN...LEE TROUGH WILL BEGIN TO
STRENGTHEN. INCREASING GRADIENT AND EXPECTED 3 HOUR PRESSURE FALLS
WOULD SUPPORT BREEZY SOUTHERLY WINDS DEVELOPING ACROSS THE AREA
DURING THE DAY. THERE WILL BE PLENTY OF SUN TO ALLOW HEATING AS 850
MB TEMPERATURES INCREASE 3 TO 5 DEGREES C FROM THE PREVIOUS DAY. SO
BASED ON THAT...RECENT BIASES...AND BETTER PERFORMING GUIDANCE...
RAISED THE MAXES ACCORDINGLY. LOW TEMPERATURES COULD STAY RATHER
MILD AS ATMOSPHERE STAYS WELL MIXED DUE TO STRENGTHENING LEE TROUGH.

SUNDAY/SUNDAY NIGHT...MODELS THEN START DIVERGING IN HOW THEY HANDLE
INCOMING UPPER TROUGH IN REGARDS TO SPEED AND AMPLITUDE. THIS
AFFECTS NUMEROUS PARAMETERS/FIELDS OF THE FORECAST. CURRENTLY THE
PATTERN OUT IN THE PACIFIC IS RATHER AMPLIFIED WITH A STRONG JET
STILL COMING DOWN THE WEST SIDE OF THE INCOMING UPPER TROUGH. THAT
WOULD SUPPORT HAVING A SLOWER AND MORE AMPLIFIED INCOMING UPPER
TROUGH. THIS PRETTY MUCH DISCOUNTS THE NAM AND THE SREF ARE VERY
FAST. MOST OF THE REMAINING OUTPUT IS CLOSE TO EACH OTHER ON THE
POSITION OF THE UPPER TROUGH AND RESULTING SURFACE PATTERN. GEFS
OUTPUT IS ALSO VERY SUPPORTIVE OF THE SLOWER SOLUTIONS WHICH ARE
THE GFS...ECMWF...UKMET AND CANADIAN.

SO WILL BASE FORECAST ON THOSE BUT CONFIDENCE IS A LITTLE BELOW
AVERAGE. MAIN SURFACE CONVERGENCE LIES NEAR THE WESTERN PORTION OF
THE FORECAST AREA ALONG WITH ACCOMPANYING MID/UPPER LIFT. CAP IS
ALSO THE WEAKEST THERE AS WELL. ALL THIS PLUS THE DETERMINISTIC QPF
AND GEFS PROBABILITY OF .05 SUPPORTS PULLING THE CHANCE OF
THUNDERSTORMS FURTHER WEST IN THE AFTERNOON. SO ADJUSTED THAT
ACCORDINGLY. AS STATED IN THE PREVIOUS FORECAST...MOISTURE COULD BE
THE LIMITING FACTOR ON COVERAGE AND SEVERITY. HOWEVER...LAPSE RATES
ARE VERY GOOD WITH VERY STRONG MID/UPPER LEVEL INDICATED...MAINLY
DURING THE EVENING. VERY STRONG PV ANOMALY ASSOCIATED WITH THIS
SYSTEM. PREVIOUS FORECAST HAS HIGH CHANCE IN THERE AND CONSIDERING
THE UNCERTAINTY BUT THE STRENGTH OF THE SYSTEM...FELT IT WAS
REASONABLE TO KEEP THOSE POPS.

VERY STRONG SYSTEM APPROACHING WILL CAUSE THE LEE TROUGH TO
STRENGTHEN EVEN MORE. PRESSURE GRADIENT AND 3 HOUR PRESSURE FALLS
DEFINITELY SUPPORT WINDY/NEAR WIND ADVISORY CONDITIONS. SO INCREASED
WIND SPEEDS TO NEAR WIND ADVISORY. 850 MB TEMPERATURES SUPPORT
HAVING HIGH TEMPERATURES NEAR WHAT THE EXPECTED SATURDAY MAXES ARE.
SO ADJUSTED ACCORDINGLY.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 301 AM MDT FRI SEP 20 2013

EARLY MONDAY...ECMWF AND GFS PLACE THE UPPER LEVEL SHORTWAVE TROUGH
AXIS OVER NORTHEAST COLORADO WITH THE COLD FRONT BISECTING THE
FORECAST AREA. THE NAM IS THE MUCH FASTER OUTLIER AND PER WPC
MODEL DIAGNOSTICS DISCUSSION A BLEND OF THE GFS AND ECMWF IS
FAVORED FOR POSITION/TIMING. SHOWERS AND THUNDERSTORMS SHOULD BE
LIMITED TO THE EASTERN HALF OF THE FORECAST AREA MONDAY
MORNING...POSSIBLY THROUGH EARLY AFTERNOON DEPENDING ON TIMING.

AS THE SHORTWAVE TROUGH MOVES QUICKLY NORTHEAST...STRONG WESTERLY
MID/UPPER FLOW DEVELOPS OVER THE NORTHERN ROCKIES AND NORTHERN
PLAINS BY TUESDAY AND LEE SIDE TROUGH STRENGTHENS IN RESPONSE. VERY
SUBTLE UPPER LEVEL RIDGING MAY BE PRESENT ON TUESDAY BUT NOT ENOUGH
FOR TEMPERATURES TO SIGNIFICANTLY EXCEED NORMAL VALUES. A
SIGNIFICANT UPPER TROUGH WILL DEVELOP OVER THE WESTERN CONUS BY
WEDNESDAY. MODELS DISAGREE ON THE TIMING AND POSITION OF THIS
TROUGH...ALBEIT TO A LESSER EXTENT THAN PREVIOUS RUNS. GFS IS THE
QUICKEST AT EJECTING IT NORTHEASTWARD. EVEN SO...GFS ENSEMBLE MEAN
QPF REMAINS NORTH AND NORTHWEST OF THE FORECAST AREA THROUGH THE END
OF THE EXTENDED PERIOD...SO THE FORECAST REMAINS DRY BEYOND MONDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 522 AM MDT FRI SEP 20 2013

VERY LIGHT WINDS AND SMALL TEMPERATURE DEW POINT DEPRESSION AT
MCK COULD RESULT IN FOG REDUCTING VISIBILITY BRIEFLY BETWEEN 12Z
AND 14Z. IF THIS OCCURS IT WILL BE BRIEF AND LIKELY REMAIN WITHIN
VFR CATEGORY. VFR CONDITIONS ARE EXPECTED TO CONTINUE AT BOTH GLD
AND MCK FOR THE NEXT 24 HOURS. WINDS WILL BE LIGHT AND VARIABLE
EARLY AND STRENGTHEN TO AROUND 5 TO 10 KNOTS LATER THIS AFTERNOON
AS A SURFACE HIGH MOVES EAST OF THE AREA. THE NAM MODEL IS MORE
MOIST THAN OTHERS AT THE TOP OF THE MIXED LAYER THIS
AFTERNOON...AND THIS COULD RESULT IN FEW/SCATTERED CUMULUS
DEVELOPING.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...BULLER
LONG TERM...BRB
AVIATION...BRB







AREA FORECAST DISCUSSION

NWS PITTSBURGH PA

 1032 AM EDT FRI SEP 20 2013

.SYNOPSIS...
A COLD FRONT WILL BRING RAIN TONIGHT AND SATURDAY. HIGH PRESSURE
WILL THEN BRING A STRETCH OF DRY WEATHER.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH 845AM UPDATE...PRIMARY CHANGE WAS TO POPS FOR THE MORNING AND
EARLY AFTERNOON HOURS. A LINE OF RAIN HAS DEVELOPED OVER THE LAST
1-2 HOURS ACROSS THE NORTHERN WEST VIRGINIA PANHANDLE...WHICH
APPEARS TO BE ALIGNED ALONG A 850MB TEMPERATURE GRADIENT. THE RAP
AND HRRR BOTH SHOW THE LINE PERSISTING FOR THE NEXT SEVERAL
HOURS...AND HAVE RAISED POPS ALONG THIS LINE. AS THE GRADIENT
MOVES EAST...HAVE BLENDED POPS BACK INTO PREVIOUS FORECAST BY LATE
AFTERNOON. ALSO INCREASED CLOUD COVER INTO THE MID MORNING. AM
STILL BEING SOMEWHAT OPTIMISTIC THAT CLOUD COVER WILL BEGIN TO
DISSIPATE LATER THIS MORNING...BUT A MORE REALISTIC SCENARIO MAY
BE SIMILAR TO YESTERDAY...WHERE CLEARING DID NOT OCCUR UNTIL
EARLY-MID AFTERNOON.

PREVIOUS...
SHOWER ACTIVITY HAS DEVELOPED OVER PORTIONS OF NW OHIO...WESTERN
LAKE ERIE AND FURTHER NORTHWARD OVER LAKE HURON. THE BULK OF THIS
ACTIVITY IS MOVING NORTHEASTWARD ON THE LEADING EDGE OF A COUPLE
OF WEAK SHORTWAVES. IT APPEARS THAT THE CONVECTION IS BLOSSOMING
DUE TO THE ENERGY MOVING THROUGH AN AREA OF INCREASED ELEVATED
INSTABILITY. THIS SPECIFIC INSTABILITY WILL SPREAD EASTWARD THIS
MORNING. ANOTHER WAVE WILL DEVELOP AND MOVE ACROSS EASTERN OHIO
LATE THIS MORNING AND THEN DRIFT SOUTHEASTWARD INTO NORTHERN WEST
VIRGINIA. WILL CONTINUE WITH SLIGHT CHC/LOW CHC POPS OVER THE
WESTERN HALF TODAY.

LOOKING AT LATEST SOUNDINGS...MIXING LAYER REMAINS AROUND 1000FT
UNTIL MID TO LATE MORNING AND THEN RISES QUICKLY. AT THE SAME
TIME...THE ATMOSPHERE DRIES OUT...LIKELY DUE TO THE SUBSIDENCE
FROM THE RIDGE AND THE PUSH OF WAA ALOFT. WILL HOLD ONTO CLOUD
COVER THROUGH MOST OF THE MORNING THEN INCREASE SUNSHINE IN THE
AFTERNOON...MAINLY IN THE EAST. WITH AN INCREASE IN SUNSHINE AND
A MODEST DESTABILIZATION OF THE ATMOSPHERE...A SHOWER OR STORM
COULD POP UP...THIS AFTERNOON.

TEMPS WILL BE TRICKY TODAY. WITH LOW CLOUDS MIXING OUT...MIXING
LAYER INCREASING AND THUS TAPING INTO THE WARMER AIR ALOFT...WILL
GO JUST ABOVE GUIDANCE TODAY FOR HIGHS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
STILL TIMING ISSUES BETWEEN THE MODEL SOLUTIONS WITH FRONTAL
PASSAGE. NAM AND NOW THE SREF ARE THE FASTEST...GFS THE SLOWEST
AND THE ECMWF SOMEWHERE IN BETWEEN. TIMING DIFFERENCE BETWEEN THE
NAM/SREF SOLUTION AND THE GFS IS ABOUT 4 TO 6 HOURS. NATURALLY,
THIS WILL HAVE AN EFFECT ON BEGINNING/END TIMES...BUT OVERALL THIS
DISCREPANCY IS MANAGEABLE. EVER SO SUBTLY THE MODELS ARE GETTING
CLOSER. WILL CONTINUE WITH A MIDDLE OF THE ROAD APPROACH...
BRINGING CAT POPS TO PIT BY 06-08Z AND THEN COVERING THE ENTIRE AREA
BY 12-14Z SAT. GFS CONTINUES TO DEVELOP A SURFACE LOW ALONG THE
FRONT...BUT IT IS LESS DEFINED AND NOT AS LONG LIVED AS YESTERDAYS
RUN.

AS THE MODELS CONTINUE TO RESOLVE ASPECTS OF THE SYSTEM...CONVECTION
IS BECOMING LESS AND LESS LIKELY. ONCE AGAIN THE ATMOSPHERE
STABILIZES TONIGHT...AND WHAT LOW AND MID LEVEL FORCING...APPARENT
YESTERDAY...IS NO LONGER AS PRONOUNCED. THE MOISTURE CONVERGENCE
IS ALSO LESS ORGANIZED AND WHAT DOES EXIST SEEMS SOMEWHAT SUSPECT.
SHEAR IS NOT BAD WITH 0-6 KM BULK SHEAR AROUND 30 TO 35KTS RIGHT
ALONG THE FRONT. THE QUESTION IS WILL ANYTHING BE ABLE TO GET
STARTED...PARTICULARLY AS SHOWERS SPREAD OUT AHEAD OF THE
BOUNDARY AND COOL THE PRE-FRONTAL ATMOSPHERE. I SUPPOSE IF ISO
CONVECTION DOES GET ROLLING...WHICH WOULD BE RIGHT ALONG THE
FRONT... HEAVY DOWNPOURS ARE A GOOD BET AS PWATS REMAIN IN THE 1.7
RANGE. NOT NEARLY AS CONCERNED WITH THE WIND THREAT AS THE
MDPI/WINDEX IS VERY LOW.

CONTINUING WITH A MODEL COMPROMISE...THE BACK EDGE OF THE RAIN
SHOULD BEGIN TO REACH THE FAR WEST BY LATE SATURDAY MORNING...
REACHING THE FAR EAST BY LATE AFTERNOON. POST FRONTAL RAIN WILL BE
JUST THAT...RAIN. THE LARGE UPPER LEVEL LOW DIGGING INTO THE
NORTHERN GREAT LAKES SATURDAY WILL HELP TO PUSH THE FRONT
EASTWARD. IF THIS LOW COMES IN FASTER...RAIN WILL END SOONER.

NORTHWEST FLOW AND STRONG CAA ALOFT WILL PROVIDE MUCH COOLER TEMPS
BY SUNDAY. THIS WILL ALSO MEAN A GOOD DEAL OF CLOUD COVER ON
SUNDAY. WILL LEAVE THE AREA DRY...BUT AN ISO SHOWER IS POSSIBLE IN
THIS REGIME.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
STRONG SURFACE HIGH WILL BUILD OVERHEAD AND DOMINATE FOR MUCH OF
THE LONG TERM PERIOD. TEMPERATURES WILL START OUT BELOW SEASONAL
AVERAGES MONDAY AND GRADUALLY WARM TO NEAR NORMAL BY THURSDAY.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
MVFR AND PTCHY IFR CONDS WL CONT ACRS MUCH OF THE AREA THRU ERLY
AFTN. A BAND OF SHWRS HAS DVLPD ALG A WK DISTURBANCE AND WL BE
AFFECTING PORTS GENLY S OF BVI. SOME DOWNSLOPING E OF PIT HAS
ALLOWED FOR VFR AT LBE AND MGW AND THIS SHOULD CONT.

IMPROVEMENT IS ANTICIPATED THIS AFTN AS MIXING AND SBSDNC IMPROVE
VIA HTG AND RISING HTS IN ADVN OF DEEPENING MIDWRN TROF. SHWRS ARE
POSSIBLE OVR EC OHIO LTR THIS AFTN AS THE TROF/CDFNT DRAWS
CLOSER...HENCE WL COVER THE SCENARIO WITH A VC MENTION AT
ZZV...AND WL EXPAND THE MENTION INTO OTHER TERMINALS AS EVENING
FALLS.

.OUTLOOK.../SATURDAY THROUGH TUESDAY/...
WIDESPREAD RESTRICTIONS CAN BE EXPECTED THROUGH SAT NGT AS RAIN
DVLPS WITH A CROSSING CDFNT. HIGH PRES WL BUILD IN THE WAKE OF THE
FRONT AND RTN GENL VFR FOR THE FIRST HALF OF NXT WEEK.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$







AREA FORECAST DISCUSSION

NWS PITTSBURGH PA

 844 AM EDT FRI SEP 20 2013

.SYNOPSIS...
A COLD FRONT WILL BRING RAIN TONIGHT AND SATURDAY. HIGH PRESSURE
WILL THEN BRING A STRETCH OF DRY WEATHER.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH 845AM UPDATE...PRIMARY CHANGE WAS TO POPS FOR THE MORNING AND
EARLY AFTERNOON HOURS. A LINE OF RAIN HAS DEVELOPED OVER THE LAST
1-2 HOURS ACROSS THE NORTHERN WEST VIRGINIA PANHANDLE...WHICH
APPEARS TO BE ALIGNED ALONG A 850MB TEMPERATURE GRADIENT. THE RAP
AND HRRR BOTH SHOW THE LINE PERSISTING FOR THE NEXT SEVERAL
HOURS...AND HAVE RAISED POPS ALONG THIS LINE. AS THE GRADIENT
MOVES EAST...HAVE BLENDED POPS BACK INTO PREVIOUS FORECAST BY LATE
AFTERNOON. ALSO INCREASED CLOUD COVER INTO THE MID MORNING. AM
STILL BEING SOMEWHAT OPTIMISTIC THAT CLOUD COVER WILL BEGIN TO
DISSIPATE LATER THIS MORNING...BUT A MORE REALISTIC SCENARIO MAY
BE SIMILAR TO YESTERDAY...WHERE CLEARING DID NOT OCCUR UNTIL
EARLY-MID AFTERNOON.

PREVIOUS...
SHOWER ACTIVITY HAS DEVELOPED OVER PORTIONS OF NW OHIO...WESTERN
LAKE ERIE AND FURTHER NORTHWARD OVER LAKE HURON. THE BULK OF THIS
ACTIVITY IS MOVING NORTHEASTWARD ON THE LEADING EDGE OF A COUPLE
OF WEAK SHORTWAVES. IT APPEARS THAT THE CONVECTION IS BLOSSOMING
DUE TO THE ENERGY MOVING THROUGH AN AREA OF INCREASED ELEVATED
INSTABILITY. THIS SPECIFIC INSTABILITY WILL SPREAD EASTWARD THIS
MORNING. ANOTHER WAVE WILL DEVELOP AND MOVE ACROSS EASTERN OHIO
LATE THIS MORNING AND THEN DRIFT SOUTHEASTWARD INTO NORTHERN WEST
VIRGINIA. WILL CONTINUE WITH SLIGHT CHC/LOW CHC POPS OVER THE
WESTERN HALF TODAY.

LOOKING AT LATEST SOUNDINGS...MIXING LAYER REMAINS AROUND 1000FT
UNTIL MID TO LATE MORNING AND THEN RISES QUICKLY. AT THE SAME
TIME...THE ATMOSPHERE DRIES OUT...LIKELY DUE TO THE SUBSIDENCE
FROM THE RIDGE AND THE PUSH OF WAA ALOFT. WILL HOLD ONTO CLOUD
COVER THROUGH MOST OF THE MORNING THEN INCREASE SUNSHINE IN THE
AFTERNOON...MAINLY IN THE EAST. WITH AN INCREASE IN SUNSHINE AND
A MODEST DESTABILIZATION OF THE ATMOSPHERE...A SHOWER OR STORM
COULD POP UP...THIS AFTERNOON.

TEMPS WILL BE TRICKY TODAY. WITH LOW CLOUDS MIXING OUT...MIXING
LAYER INCREASING AND THUS TAPING INTO THE WARMER AIR ALOFT...WILL
GO JUST ABOVE GUIDANCE TODAY FOR HIGHS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
STILL TIMING ISSUES BETWEEN THE MODEL SOLUTIONS WITH FRONTAL
PASSAGE. NAM AND NOW THE SREF ARE THE FASTEST...GFS THE SLOWEST
AND THE ECMWF SOMEWHERE IN BETWEEN. TIMING DIFFERENCE BETWEEN THE
NAM/SREF SOLUTION AND THE GFS IS ABOUT 4 TO 6 HOURS. NATURALLY,
THIS WILL HAVE AN EFFECT ON BEGINNING/END TIMES...BUT OVERALL THIS
DISCREPANCY IS MANAGEABLE. EVER SO SUBTLY THE MODELS ARE GETTING
CLOSER. WILL CONTINUE WITH A MIDDLE OF THE ROAD APPROACH...
BRINGING CAT POPS TO PIT BY 06-08Z AND THEN COVERING THE ENTIRE AREA
BY 12-14Z SAT. GFS CONTINUES TO DEVELOP A SURFACE LOW ALONG THE
FRONT...BUT IT IS LESS DEFINED AND NOT AS LONG LIVED AS YESTERDAYS
RUN.

AS THE MODELS CONTINUE TO RESOLVE ASPECTS OF THE SYSTEM...CONVECTION
IS BECOMING LESS AND LESS LIKELY. ONCE AGAIN THE ATMOSPHERE
STABILIZES TONIGHT...AND WHAT LOW AND MID LEVEL FORCING...APPARENT
YESTERDAY...IS NO LONGER AS PRONOUNCED. THE MOISTURE CONVERGENCE
IS ALSO LESS ORGANIZED AND WHAT DOES EXIST SEEMS SOMEWHAT SUSPECT.
SHEAR IS NOT BAD WITH 0-6 KM BULK SHEAR AROUND 30 TO 35KTS RIGHT
ALONG THE FRONT. THE QUESTION IS WILL ANYTHING BE ABLE TO GET
STARTED...PARTICULARLY AS SHOWERS SPREAD OUT AHEAD OF THE
BOUNDARY AND COOL THE PRE-FRONTAL ATMOSPHERE. I SUPPOSE IF ISO
CONVECTION DOES GET ROLLING...WHICH WOULD BE RIGHT ALONG THE
FRONT... HEAVY DOWNPOURS ARE A GOOD BET AS PWATS REMAIN IN THE 1.7
RANGE. NOT NEARLY AS CONCERNED WITH THE WIND THREAT AS THE
MDPI/WINDEX IS VERY LOW.

CONTINUING WITH A MODEL COMPROMISE...THE BACK EDGE OF THE RAIN
SHOULD BEGIN TO REACH THE FAR WEST BY LATE SATURDAY MORNING...
REACHING THE FAR EAST BY LATE AFTERNOON. POST FRONTAL RAIN WILL BE
JUST THAT...RAIN. THE LARGE UPPER LEVEL LOW DIGGING INTO THE
NORTHERN GREAT LAKES SATURDAY WILL HELP TO PUSH THE FRONT
EASTWARD. IF THIS LOW COMES IN FASTER...RAIN WILL END SOONER.

NORTHWEST FLOW AND STRONG CAA ALOFT WILL PROVIDE MUCH COOLER TEMPS
BY SUNDAY. THIS WILL ALSO MEAN A GOOD DEAL OF CLOUD COVER ON
SUNDAY. WILL LEAVE THE AREA DRY...BUT AN ISO SHOWER IS POSSIBLE IN
THIS REGIME.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
STRONG SURFACE HIGH WILL BUILD OVERHEAD AND DOMINATE FOR MUCH OF
THE LONG TERM PERIOD. TEMPERATURES WILL START OUT BELOW SEASONAL
AVERAGES MONDAY AND GRADUALLY WARM TO NEAR NORMAL BY THURSDAY.

&&

.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
IFR AND LOW END MVFR ST AND FOG WL CONT TO PLAGUE UPR OH VALLEY
TERMINALS THIS MRNG AS A WEAK DISTURBANCE PRVDS BROAD ASCENT OVR
A SATURATED...BUT CAPPED BNDRY LYR. SOME -SHWRS MAY ALSO AFFECT THE
ZZV AND HLG AREAS THROUGH THE POSTDAWN HRS AS WEAK ELEVATED
CONVECTION OVR OH SHOULD PERSIST GIVEN MDL SOUNDING- PROGNOSIS.
THE OTHER EXCEPTIONS MAY BE AT LBE AND MGW WHERE DOWNSLOPE MAY BE
SUFFICIENT TO OFFSET THE MSTR POOLING UNDR THE INVERSION.

RAPID IMPROVEMENT IS ANTICIPATED LTR THIS MRNG AS MIXING AND
SBSDNC IMPROVE VIA HTG AND RISING HTS IN ADVN OF DEEPENING MIDWRN
TROF. SHWRS ARE POSSIBLE OVR EC OHIO LTR THIS AFTN AS THE
TROF/CDFNT DRAWS CLOSER...HENCE WL COVER THE SCENARIO WITH A VC
MENTION AT ZZV...AND WL EXPAND THE MENTION INTO OTHER TERMINALS AS
EVENING FALLS.

.OUTLOOK.../SATURDAY THROUGH TUESDAY/...
WIDESPREAD RESTRICTIONS CAN BE EXPECTED THROUGH SAT NGT AS RAIN
DVLPS WITH A CROSSING CDFNT. HIGH PRES WL BUILD IN THE WAKE OF THE
FRONT AND RTN GENL VFR FOR THE FIRST HALF OF NXT WEEK.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$







AREA FORECAST DISCUSSION...UPDATED

NWS ST LOUIS MO

 1040 AM CDT Fri Sep 20 2013

.UPDATE:
Issued at 1040 AM CDT Fri Sep 20 2013

15z surface obs show cold front knocking on the door of STL metro,
just to the NW, and is expected to move thru during the midday
hours. Low clouds expected to linger for a couple hours after
FROPA, with a thick CS cloud deck hanging around for thru the rest
of the afternoon over many areas. This thick cloud cover will
result in limited sunshine and combined with somewhat decent lo
level CAA, will result in very limited temp recoveries behind the
front today with most locales seeing near steady temps.

Substantial clearing will take place early this evening with
expected departure of thick high clouds and associated temp and
wind dropoff will occur as well.

Rain will experience one final surge slightly back to the NW as it
rides up I-44 in MO during the midday and early afternoon hours
before it then accelerates off and out of the area later in the
afternoon. Some patchy drizzle has also been reported near and
just behind the cold front and have added that in as well,
sharpening up the gradient between areas that should receive
measurable rainfall from those that do not but may still see some
precipitation. Removed thunder from forecast with instability very
limited from here on out.

TES

&&

.SHORT TERM:  (Through Tonight)
Issued at 326 AM CDT Fri Sep 20 2013

Main concern will be how quickly the rain will exit the area today.
Cold front currently extends from Kirksville to Sedalia to Nevada.
Ahead of it, there is a large band of rain with the leading edge
of the thunderstorms extending from just northeast of metro St.
Louis southwestward West Plains. This line should continue to
move east in the near term...though there will continue to be some
weakening in this line as the RAP shows the 925-850mb moisture
convergence diminishing. The cold front will continue to move
southeast today, clearing the CWA by 21Z. The main band of rain
with embedded thunderstorms will be found ahead of it, aided by
ascent from the front and the deep upper through moving across the
central CONUS. This is generally follows the latest runs of the
HRRR which shows rain slowly spreading southeast with time.

With clouds and rain today, temperatures will be much cooler than
yesterday. Some locations in south and east may not see much
diurnal recovery.

Britt

.LONG TERM: (Saturday through Wednesday)
Issued at 326 AM CDT Fri Sep 20 2013

Forecast remains dry in the long term.  Strong subsidence sets in
the wake of the upper trough as upper ridge builds in over the
region by late Sunday. Deep trough that enters the West Coast over
the weekend still shears out before it can give us any rain. Then
GFS/ECMWF both begin to amplify pattern over the CONUS by the
middle of next week with a trough over the Rockies and ridge over
the Mississippi Valley on Wednesday.

A dry airmass and light winds/mainly clear skies should allow for
some excellent radiational cooling at night. Went a few degrees
below guidance for lows over the weekend into early next week.

Britt

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 553 AM CDT Fri Sep 20 2013

COLD FRONT MOVING THROUGH THE AREA WILL BE THE FOCUS OF THE
FORECAST. FRONT SHOULD BE THROUGH UIN AND COU IN A 12 - 13Z
TIMEFRAME. PRECIPITATION HAS MOVED WELL SOUTH OF THESE AREA SO
THEY LOOK TO STAY DRY. MDLS ARE TRYING TO HOLD PRECIP ALONG I-44
SOUTH UNTIL ABOUT MIDDAY. WITH THE UPPER TROF HANGING BACK THIS IS
CERTAINLY POSSIBLE. HOWEVER RADAR LOOPS SHOW A SHRINKING TREND AND
A DECENT PUSH TO THE SOUTHEAST ALONG THE BACK EDGE. THUS I WILL
KEEP MOST OF THE LINGERING LIGHT RAIN SOUTH AND EAST OF ANY
TERMINALS. OTHER ISSUE WILL BE IFR/MFVR CEILINGS BEHIND THE FRONT.
CURRENT OBSERVATION SHOW A MIXED BAD OF CLOUDS SO DON`T FEEL ANY
ONE DIRECTION WILL BE THE ANSWER. UIN LOOKS TO BE IFR FOR A COUPLE
OF HOURS AND COU MAY COME DOWN...BUT WILL NOT HOLD IT IN LONG.

Specifics for KSTL: FRONT SHOULD BE THROUGH ABOUT 15 - 16Z. WILL
KEEP SOME LIGHT RAIN IN...6SM UNTIL THEN...ALTHOUGH THAT MAY BE
TOO LONG. RADAR ECHOES CONTINUE TO SHRINK. SOME IFR CLOUDS IN THE
AREA BUT DO NOT EXPECT THEM TO HOLD LONG.

JPK

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







AREA FORECAST DISCUSSION...UPDATED AVIATION

NWS ST LOUIS MO

 611 AM CDT Fri Sep 20 2013

.SHORT TERM:  (Through Tonight)
Issued at 326 AM CDT Fri Sep 20 2013

Main concern will be how quickly the rain will exit the area today.
Cold front currently extends from Kirksville to Sedalia to Nevada.
Ahead of it, there is a large band of rain with the leading edge
of the thunderstorms extending from just northeast of metro St.
Louis southwestward West Plains. This line should continue to
move east in the near term...though there will continue to be some
weakening in this line as the RAP shows the 925-850mb moisture
convergence diminishing. The cold front will continue to move
southeast today, clearing the CWA by 21Z. The main band of rain
with embedded thunderstorms will be found ahead of it, aided by
ascent from the front and the deep upper through moving across the
central CONUS. This is generally follows the latest runs of the
HRRR which shows rain slowly spreading southeast with time.

With clouds and rain today, temperatures will be much cooler than
yesterday. Some locations in south and east may not see much
diurnal recovery.

Britt

.LONG TERM: (Saturday through Wednesday)
Issued at 326 AM CDT Fri Sep 20 2013

Forecast remains dry in the long term.  Strong subsidence sets in
the wake of the upper trough as upper ridge builds in over the
region by late Sunday. Deep trough that enters the West Coast over
the weekend still shears out before it can give us any rain. Then
GFS/ECMWF both begin to amplify pattern over the CONUS by the
middle of next week with a trough over the Rockies and ridge over
the Mississippi Valley on Wednesday.

A dry airmass and light winds/mainly clear skies should allow for
some excellent radiational cooling at night. Went a few degrees
below guidance for lows over the weekend into early next week.

Britt

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 553 AM CDT Fri Sep 20 2013

COLD FRONT MOVING THROUGH THE AREA WILL BE THE FOCUS OF THE
FORECAST. FRONT SHOULD BE THROUGH UIN AND COU IN A 12 - 13Z
TIMEFRAME. PRECIPITATION HAS MOVED WELL SOUTH OF THESE AREA SO
THEY LOOK TO STAY DRY. MDLS ARE TRYING TO HOLD PRECIP ALONG I-44
SOUTH UNTIL ABOUT MIDDAY. WITH THE UPPER TROF HANGING BACK THIS IS
CERTAINLY POSSIBLE. HOWEVER RADAR LOOPS SHOW A SHRINKING TREND AND
A DECENT PUSH TO THE SOUTHEAST ALONG THE BACK EDGE. THUS I WILL
KEEP MOST OF THE LINGERING LIGHT RAIN SOUTH AND EAST OF ANY
TERMINALS. OTHER ISSUE WILL BE IFR/MFVR CEILINGS BEHIND THE FRONT.
CURRENT OBSERVATION SHOW A MIXED BAD OF CLOUDS SO DON`T FEEL ANY
ONE DIRECTION WILL BE THE ANSWER. UIN LOOKS TO BE IFR FOR A COUPLE
OF HOURS AND COU MAY COME DOWN...BUT WILL NOT HOLD IT IN LONG.

Specifics for KSTL: FRONT SHOULD BE THROUGH ABOUT 15 - 16Z. WILL
KEEP SOME LIGHT RAIN IN...6SM UNTIL THEN...ALTHOUGH THAT MAY BE
TOO LONG. RADAR ECHOES CONTINUE TO SHRINK. SOME IFR CLOUDS IN THE
AREA BUT DO NOT EXPECT THEM TO HOLD LONG.

JPK

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







AREA FORECAST DISCUSSION

NWS BUFFALO NY

 801 AM EDT FRI SEP 20 2013

.SYNOPSIS...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL PROVIDE ANOTHER DAY
OF DRY WEATHER FOR MOST OF THE REGION TODAY WITH TEMPERATURES RISING
TO ABOVE NORMAL. RAIN IS EXPECTED TONIGHT INTO SATURDAY AS A COLD
FRONT MOVES EAST ACROSS THE GREAT LAKES. TEMPERATURES WILL FALL BACK
BELOW NORMAL WITH DRY CONDITIONS EXPECTED BEHIND THE COLD FRONT FOR
SUNDAY INTO MUCH OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE WILL REMAIN ANCHORED OFF THE MID ATLANTIC COAST TODAY.
A STEADY INFLUX OF LOW LEVEL MOISTURE WILL PUSH NORTHWARD INTO
WESTERN NEW YORK ON THE WESTERN SIDE OF THE HIGH AS A WARM
FRONTAL BOUNDARY CURRENTLY STRETCHING ACROSS THE SOUTHERN GREAT
LAKES/OHIO VALLEY ADVANCES TOWARD THE REGION. UPSTREAM RADARS
SHOWING GOOD COVERAGE OF CONVECTION ASSOCIATED WITH THE WARM FRONT
BUT ALL SHORT TERM MODELS INCLUDING HRRR AND 00Z SPC SSEO RUN
DISSIPATE THIS ACTIVITY AS IT WORKS EASTWARD INTO THE RIDGE THIS
MORNING. THERE WILL BE SOME OPPORTUNITY FOR CONVECTIVE DEVELOPMENT
ACROSS FAR WESTERN NEW YORK THIS AFTERNOON AS ATMOSPHERE
DESTABILIZES...BUT FOR THE MOST PART THE DAY LOOKS DRY FOR A GOOD
PORTION OF THE AREA. A WARM DAY IN STORE WITH TEMPERATURES WITH
HIGHS IN THE UPPER 70S TO LOWER 80S...A SOLID 10 DEGREES ABOVE
NORMAL.

TONIGHT...UPPER TROUGH CURRENTLY OVER THE MANITOBA BORDER STRETCHING
DOWN THROUGH THE NORTHERN PLAINS WILL TRACK EAST AND INTO THE GREAT
LAKES. THIS WILL DRIVE A COLD FRONT TOWARD WESTERN NEW YORK LATE
TONIGHT. DEEP LAYER FORCING WILL ACCOMPANY THE FRONT...WITH PVA AND
RIGHT ENTRANCE REGION FORCING/UPPER DIFFLUENCE STACKED ABOVE THE
FRONT...GENERATING A WIDESPREAD COVERAGE OF SHOWERS AND
THUNDERSTORMS INTO WESTERN NEW YORK...ESPECIALLY AFTER 06Z. SEVERE
POTENTIAL LOOKS LIMITED WITH DIMINISHING INSTABILITY. HOWEVER WITH
THE APPROACH OF THE UPPER TROUGH...UNIDIRECTIONAL WIND PROFILES
DEVELOP WITH 0-6 KM BULK SHEAR VALUES INCREASING TO 30 TO 35
KNOTS...NOT COMPLETELY RULING OUT A FEW GUSTY THUNDERSTORMS.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
THE UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS STATES TODAY WILL
MOVE TO THE GREAT LAKES AND NORTHEASTERN STATES DURING THE WEEKEND.
THE TROUGH WILL PUSH A COLD FRONT EASTWARD ACROSS THE REGION LATE
FRIDAY NIGHT AND INTO CENTRAL NY BY LATE SATURDAY. ABUNDANT MOISTURE
WILL POOL ALONG AND AHEAD OF COLD FRONT...PROVIDED BY THE REMNANTS
OF EASTERN PACIFIC TROPICAL SYSTEMS...WITH A LINE OF THUNDERSTORMS
AND TRAILING STRATIFORM RAIN INTO SATURDAY MORNING AS THE FRONT
MOVES EAST. RAIN AMOUNTS WITH THIS SYSTEM MIGHT EXCEED AN INCH IN
SOME LOCATIONS.

REMAINING LOW LEVEL MOISTURE BEHIND THE FRONT WILL PRODUCE AREAS OF
DRIZZLE IN UPSLOPE REGIONS SATURDAY NIGHT AS AN INVERSION TRAPS
MOISTURE BELOW 800MB.  HIGH PRESSURE BUILDING ACROSS REGION ON
SUNDAY WILL BRING A SLOW CLEARING TREND THROUGH THE DAY.
TEMPERATURES WILL BE THE MID 40S TO LOW 50S SATURDAY NIGHT AND THE
HIGHS ON SUNDAY WILL ONLY BE IN THE MID 50S TO AROUND 60 UNDER
COLDER NORTHWESTERLY FLOW. NEARLY CLEAR SKIES SUNDAY NIGHT WILL
YIELD A CHILLY NIGHT WITH VALLEY FOG FORMING.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
HIGH PRESSURE MOVES INTO THE LOWER GREAT LAKES REGION NEXT
WEEK...PROVIDING DRY WEATHER ACROSS THE REGION FOR MOST IF NOT ALL
OF NEXT WEEK.  EXPECT TYPICAL EARLY FALL SEASON HIGHS AND LOWS WITH
ABUNDANT DAYTIME SUNSHINE...CLEAR SKIES OVERNIGHT AND PATCHY FOG IN
INLAND VALLEYS DURING THE EARLY MORNING HOURS.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL MAINTAIN THROUGH
THE DAY TODAY. A COLD FRONT WILL PUSH EAST ACROSS THE REGION
DURING THE FIRST HALF OF SATURDAY. A MVFR LEVEL STRATOCU DECK
ACROSS SOUTHWESTERN NEW YORK WILL IMPROVE TO VFR BETWEEN 13Z AND
15Z. WIDESPREAD VFR CONDITIONS ARE THEN EXPECTED THE REMAINDER OF
THE DAY.

TONIGHT INTO SATURDAY...AN APPROACHING COLD FRONT WILL BRING
SHOWERS AND A FEW THUNDERSTORMS TO THE REGION...PRIMARILY AFTER 09Z
AS SOUTHWEST FLOW TRANSPORTS MOISTURE NORTHWARD. MVFR BECOMING
IFR WILL DEVELOP ACROSS THE WEST TOWARD MORNING WORKING EAST
THROUGH THE DAY.

OUTLOOK...
SATURDAY NIGHT...BECOMING VFR.
SUNDAY THROUGH TUESDAY...VFR.

&&

.MARINE...
HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL PROVIDE TRANQUIL
WEATHER THROUGH TODAY. EXPECT LIGHT WINDS AND MINIMAL WAVES. A COLD
FRONT WILL APPROACH THE LOWER GREAT LAKES TONIGHT INTO SATURDAY
WITH WAVES INCREASING ON THE EASTERN ENDS OF THE LAKES. SMALL CRAFT
CONDITIONS MAY BE REACHED ON THE EASTERN HALF OF LAKE ONTARIO
TONIGHT AS THE FRONT APPROACHES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA
SHORT TERM...WCH
LONG TERM...ZAFF
AVIATION...TMA
MARINE...TMA








AREA FORECAST DISCUSSION

NWS PORTLAND OR

 314 AM PDT FRI SEP 20 2013

.SYNOPSIS... A PACIFIC FRONT WILL BRING DETERIORATING CONDITIONS TO
THE AREA TODAY. RAIN WILL SPREAD INTO THE COAST BY MIDDAY AND ACROSS
THE WILLAMETTE VALLEY BY THE MID TO LATE AFTERNOON HOURS. ADDITIONAL
RAIN SHOWERS WILL CONTINUE FRIDAY NIGHT INTO SATURDAY WITH PERHAPS A
FEW LIGHTNING STRIKES. A STRONGER FRONT WILL BRING WINDY CONDITIONS
TO THE COAST...BREEZY CONDITIONS INLAND...AND ANOTHER ROUND OF
WIDESPREAD RAIN TO THE AREA SUNDAY. COOL AND UNSETTLED WEATHER SHOULD
CONTINUE FOR THE FIRST HALF OF NEXT WEEK WITH PERIODS OF SHOWERS
BEFORE SOME DRYING FOR THE LATTER HALF OF NEXT WEEK.

&&

.SHORT TERM...INFRARED SATELLITE IMAGERY SHOWS WAVES OF SHOWERS
ROLLING NORTHWARD ALONG A FRONTAL BOUNDARY APPROXIMATELY 100-150
MILES OFF THE PACIFIC NORTHWEST COAST THIS MORNING. SUFFICIENTLY DEEP
INSTABILITY IN THE VICINITY OF THE FRONT HAS RESULTED IN A FEW
LIGHTNING STRIKES TOWARDS VANCOUVER ISLAND OVERNIGHT. KLGX DOPPLER
RADAR INDICATES A FEW LIGHT SHOWERS AHEAD OF THE MAIN FRONTAL BAND
MAY BRING LIGHT SPOTTY SHOWERS TO THE COAST THIS MORNING. HRRR AND A
LINEAR EXTRAPOLATION OF THE RADAR INDICATES THE STEADIER AND HEAVIER
RAIN WILL LIKELY HIT THE COAST DURING THE LATE MORNING HOURS AND
SPREAD INTO THE WILLAMETTE VALLEY DURING THE MID TO LATE AFTERNOON
HOURS. THERE IS SOME CONCERN THAT WE COULD SEE CONVECTION WITH THE
FRONT AS IT PUSHES INLAND LATE THIS AFTERNOON AND EARLY
EVENING...BUT FOR NOW KEPT THE THUNDER MENTION PRIMARILY LIMITED TO
THE COAST AND CENTRAL OREGON CASCADES.

A COLD UNSTABLE AIRMASS WILL SLOWLY WORK ITS WAY OVER THE AREA
TONIGHT INTO SATURDAY. THIS SHOULD RESULT IN PERIODS OF SUN BREAKS
BETWEEN SHOWERS SATURDAY WITH A FEW RUMBLES OF THUNDER POSSIBLE JUST
ABOUT ANYWHERE. SNOW LEVELS WILL LOWER TO NEAR 6-6.5KFT SATURDAY.

BRIEF SHORTWAVE RIDGING SATURDAY NIGHT SHOULD RESULT IN SHOWERS
DECREASING ACROSS THE AREA. HOWEVER...THE RESPITE WILL BE SHORT
LIVED AS THE NEXT STORM SYSTEM SPREADS WIDESPREAD RAIN FROM
NORTHWEST TO SOUTHEAST ACROSS THE AREA SUNDAY. IN ADDITION...A
STRONG FRONT WILL BRING WINDY CONDITIONS TO THE COAST AND BREEZY
CONDITIONS INLAND ON SUNDAY. THE NAM IS THE STRONGEST SOLUTION AT THIS
POINT...WITH THE GFS BACKING OFF JUST A BIT ON 925MB AND 850MB WINDS
FROM PREVIOUS MODEL RUNS SO CONFIDENCE IS NOT PARTICULARLY HIGH A HIGH
WIND PRODUCT WILL BE NEEDED FOR THE COAST. NONETHELESS...WIND GUSTS
OF AT LEAST 45 TO 55 MPH APPEAR TO BE A SAFE BET FOR MANY LOCATIONS
ALONG THE COAST.

ONSHORE FLOW WITH COOLING TEMPERATURES ALOFT SHOULD RESULT IN
ADDITIONAL ROUNDS OF SHOWERS MONDAY AND TUESDAY AS AN UPPER LEVEL
TROUGH DROPS INTO THE PACIFIC NORTHWEST. /NEUMAN

.LONG TERM...SUNDAY EVENING THROUGH THURSDAY...
EXPECT THE MAIN FRONTAL BAND TO SHIFT INLAND SUNDAY EVENING. THE
UPPER LOW ASSOCIATED WITH THIS FRONT WILL BEGIN THE EXTENDED PERIOD
OFF THE COAST OF CENTRAL B.C. THEN DIG SOUTH AND EAST AND WILL BE ON
TOP OF THE AREA TUESDAY NIGHT. WITH THE LOW TO THE NORTH WE WILL
MAINTAIN A GOOD BATCH OF ONSHORE FLOW THROUGH AT LEAST TUESDAY.
SEVERAL WAVES OF ENERGY WILL MIGRATE THROUGH THE AREA FOR PERIODS OF
SHOWERS...THOUGH EXPECT LITTLE IN THE WAY OF BREAKS IN ELEVATED
TERRAIN...AND NO OBVIOUS DRY PERIODS FOR THE LOWLANDS AS WELL.
TEMPERATURES WILL REMAIN BELOW NORMAL AND GENERALLY IN THE 60S FOR
THE LOWLANDS.

THE UPPER LOW WILL SHIFT SOUTH AND EAST OF THE AREA THROUGH THE DAY
ON WEDNESDAY. AN UPPER LEVEL RIDGE WILL BE OFFSHORE ON WEDNESDAY
EVENING AND ATTEMPT TO SLOWLY PUSH ONSHORE. THE FLOW TURNS NORTH TO
NORTHEASTERLY WHICH WILL ALLOW THE AREA TO DRY OUT THROUGH AT LEAST
FRIDAY WHILE ANOTHER FRONT ATTEMPTS TO SQUASH THE RIDGE OFFSHORE. A
RETROGRADING INLAND RIDGE MAY KEEP THIS AT BAY FOR NEXT WEEKEND.
EXPECT TEMPERATURES TO REBOUND TO AT LEAST THE LOWER 70S AND CLOSER
TO NORMAL WITH MORE IN THE WAY OF SUNSHINE AFTER MORNING FOG.
KMD/ROCKEY

&&

.AVIATION...MAINLY VFR CONDITIONS OVER THE REGION EARLY THIS
MORNING. THERE IS A CHANCE FOR PATCHY IFR CONDITIONS IN FOG THROUGH
15Z THIS MORNING ALONG THE COAST...THEN CLOUDS ARE EXPECTED TO
SPREAD OVER THE REGION. MVFR CIGS ARE LIKELY TO FORM ALONG THE COAST
THIS MORNING BETWEEN 12Z AND 18Z AHEAD OF A SLOW APPROACHING
FRONT...BUT INLAND VFR CONDITIONS ARE LIKELY TO PERSIST PAST 00Z.

KPDX AND APPROACHES...VFR EXPECTED THROUGH 00Z. CLOUDS WILL LOWER
THIS EVENING AS A FRONT MOVES IN...WITH A GOOD CHANCE FOR MVFR CIGS
AFTER RAINS MOVE IN AFTER 00Z.
&&

.MARINE...WIND FIELDS WITH THE FRONT MOVING IN THIS MORNING WERE
WEAKENING...AND AT THIS POINT IT APPEARS UNLIKELY TO SEE MORE THAN A
FEW GUSTS OVER THE SMALL CRAFT WIND CRITERIA. SEAS HOWEVER HAVE BEEN
PICKING UP QUICKLY EARLY THIS MORNING AS A WESTERLY SWELL ON THE
ORDER OF 10 TO 12 FT HAS MOVED IN. SEAS IN EXCESS OF 10 FT CAN BE
EXPECTED TO REACH THE S WA AND N OREGON COAST AROUND 3 AM...PROBABLY
A COUPLE HOURS LATER ON THE CENTRAL OREGON COAST. THE FRONT
ITSELF...WITH SE WINDS AHEAD OF IT A SW WINDS BEHIND...IS EXPECTED
TO REACH THE COAST BETWEEN 11 AM AND 2 PM.

A STRONGER SYSTEM WILL REACH THE WATERS SUN...WITH WINDS LIKELY
TOPPING OUT IN THE GALE CATEGORY. WITH THE BIGGER WINDS COME THE
PROSPECTS FOR BIGGER SEAS...LIKELY TO BE ON THE ORDER OF 15 FT BY
MON.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 6 AM PDT EARLY THIS
     MORNING FOR WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
     FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT SAT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
     5 AM PDT SAT.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...
    HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
    WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
    WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.







AREA FORECAST DISCUSSION

NWS STATE COLLEGE PA

 701 AM EDT FRI SEP 20 2013

.SYNOPSIS...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL MAINTAIN
ITS GRIP ON THE REGION TODAY. A COLD FRONT WILL PUSH EAST ACROSS
THE STATE SATURDAY. AN OMEGA BLOCK AND ASSOCIATED HIGH PRES WILL
LIKELY BE PARKED OVR THE AREA THROUGH ALL OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLEAR SKIES...A CALM WIND AND INCREASING LOW LVL MOISTURE HAS
RESULTED WIDESPREAD VALLEY FOG EARLY THIS AM. MODIS 11-3.7UM SATL
IMAGERY SHOWS THE MOST EXTENSIVE LOW STRATUS/FOG HAS FORMED ACROSS THE
NORTH CENTRAL MTNS. LEANING TOWARD AN SPS RATHER THAN AN ADVISORY
TO COVER LOCALLY DENSE FOG THIS AM.

VALLEY FOG SHOULD BURN OFF BY 13Z-14Z ACROSS MOST OF THE AREA
BASED ON 3KM HRRR SFC RH AND WHAT OCCURRED YESTERDAY. HOWEVER...STRATUS
DECK...WHICH HAS WORKED INTO SOMERSET AND WARREN COUNTIES...MAY
TAKE UNTIL ALMOST NOON TO LIFT/BREAK UP INTO SCT-BKN CU FIELD.

HIGHER PWAT AIR ON WESTERN PERIPHERY OF SFC HIGH WILL BE ACROSS
WESTERN PA AND LEAD TO A MIX OF SUN AND CU THIS AFTN...WHILE DRIER
AND MAINLY SUNNY SKIES PREVAIL ACROSS THE EASTERN COUNTIES. CAN/T
RULE OUT A VERY ISOLD LATE DAY SHRA/TSRA IN THE MORE HUMID AND
MARGINALLY UNSTABLE AIR MASS ACROSS THE W MTNS. HOWEVER...UPPER
LVL RIDGING AND ASSOC WARM MID LVL TEMPS SHOULD ENSURE A DRY DAY
FOR THE VAST MAJORITY OF THE AREA.

GEFS 925TEMPS BTWN 16C-21C FROM SE TO NW SHOULD SUPPORT HIGH TEMPS
THIS AFTN IN THE M/U70S...WITH THE WARMEST TEMPS RELATIVE TO
NORMAL ACROSS THE W MTNS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
SHORT RANGE MDLS IN AGREEMENT WITH RESPECT TO TIMING OF COLD
FRONT....WHICH SHOULD ENTER THE NW MTNS LATE SAT AM AND EXIT
EASTERN PA DURING THE EVENING HRS. DEEP SOUTHERLY FLOW AND ASSOC
ATMOSPHERIC RIVER OF ANOMALOUS PWATS WILL PRECEDE APPROACHING COLD
FRONT...BRINGING A DECENT RAINFALL TO MOST OF CENTRAL PA. LATEST
SREF AND GEFS OUTPUT INDICATE A LIKELIHOOD OF RAIN TOTALS NR 1
INCH OVR MUCH OF THE AREA WITH LOCAL TOTALS ARND 2 INCHES MOST
LIKELY ACROSS THE EASTERN HALF OF THE STATE...DUE TO POSSIBLE WEAK
WAVE AND SLOWING OF FRONT SAT EVENING. MDL CAPES ARE UNIMPRESSIVE...THE
RESULT OF ABUNDANT PRE-FRONTAL CLOUD COVER. HOWEVER...WILL MAINTAIN
SLGHT CHC OF EMBEDDED TSRA.

GEFS AND SREF OUTPUT BOTH SUPPORT POPS NR 100 PCT ACROSS THE
ENTIRE AREA SATURDAY. CURRENT MDL TIMING SUGGESTS THE EASTERN
COUNTIES MAY REMAIN DRY UNTIL THE AFTN HRS...WHILE RAIN IS LIKELY
TO BEGIN BEFORE DAWN ACROSS THE NW MTNS. BACK EDGE OF THE RAIN
SHOULD ARRIVE OVR THE W MTNS ARND 21Z AND THE EASTERN COUNTIES BY
ARND MIDNIGHT.

CLOUD COVER AND RAINFALL WILL LIKELY HOLD TEMPS IN THE M/U60S SAT
ACROSS THE ALLEGHENY PLATEAU...WHILE THE SUSQ VALLEY IS LIKELY TO
GET INTO THE L/70S BEFORE THE RAIN STARTS IN THE AFTN.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
UPPER LVL TROF AND ASSOC COLD TEMPS ALOFT WILL PASS THRU PA ON
SUNDAY...RESULTING IN A GOOD DEAL OF DIURNAL CU. CAN/T RULE OUT A
FEW SPRINKLES ACROSS THE N MTNS. HOWEVER...LOW PWAT AIR MASS IS
UNLIKELY TO PRODUCE MEASURABLE RAIN IN MANY SPOTS. ENS MEAN
925TEMPS ARE SUPPORTIVE OF HIGHS FROM JUST THE U50S ACROSS THE W
MTNS...TO THE U60S IN THE SUSQ VALLEY. A RATHER TIGHT PRES
GRADIENT BTWN DEPARTING CDFRONT AND HIGH PRES OVR THE WESTERN
LAKES SHOULD RESULT IN A FAIRLY ACTIVE NW WIND ON SUNDAY...ADDING
TO THE FALL-LIKE FEEL.

FAIRLY GOOD AGREEMENT AMONG MED RANGE GUIDANCE FOR NEXT
WEEK...MOST OF WHICH INDICATE PA WILL BE UNDER RIDGE PORTION OF
OMEGA BLOCK...RESULTING IN AN EXTENDED PERIOD OF FAIR WEATHER.
GEFS 925/850 TEMPS INDICATE DAYTIME TEMPS WILL BE NEAR TO A BIT
ABOVE NORMAL. HOWEVER...DRY AIR AND PROXIMITY OF SFC HIGH WILL
LIKELY PRODUCE SOME COOL MORNINGS.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL MAINTAIN
ITS GRIP ON THE REGION TODAY. A COLD FRONT WILL PUSH EAST ACROSS
THE STATE SATURDAY.

WIDESPREAD IFR FOG ACROSS THE NORTH/WEST WITH MORE VARIABLE
CONDITIONS ELSEWHERE AT SUNRISE. RAPID IMPROVEMENT EXPECTED IN THE
EAST...BUT AN MVFR LEVEL STRATOCU DECK EDGING IN FROM THE WEST WILL
BRING MORE GRADUAL IMPROVEMENT TO WESTERN TAFS. BUT ULTIMATELY...
BY MID MORNING /14-15Z/ VFR CONDITIONS EXPECTED TO BECOME
WIDESPREAD AND CONTINUE THROUGH THE REMAINDER OF THE DAY AND INTO
THIS EVENING. SURFACE WINDS WILL BE LIGHT FROM THE SE/S. ANY
AFTERNOON CONVECTIVE ACTIVITY WILL REMAIN WEST OF CWA.

TONIGHT INTO SATURDAY...THE FOCUS TURNS TO AN APPROACHING COLD
FRONT. AS SW FLOW INCREASES /WITH INCREASED LOW LEVEL MOISTURE
TRANSPORT/...LOWER CIGS /MVFR BECOMING IFR/ WILL DEVELOP ACROSS
THE WEST LATE THIS EVENING AND SPREAD INTO EASTERN SECTIONS
THROUGH SUNRISE SAT. THOUGH SOME SHOWERS WORK INTO NW MTNS
LATE...MAINLY LIGHT SHOWERS OR AREAS OF DRIZZLE POSS AFTER 08Z
ELSEWHERE. SATURDAY LOOKS TO BRING POOR FLYING CONDITIONS AS AREA
OF RAIN WITH ISOLATED TSTMS IMPACTS THE REGION...KEEPING CIGS IFR
MUCH OF THE DAY INTO THE EVENING.

OUTLOOK...
SAT-SAT NIGHT...COLD FRONT CROSSES REGION. RAIN AND ISO TSTMS WILL
BRING RESTRICTIONS AREA-WIDE.

SUN...MVFR CONTINUES IN SCT SHRA/AREAS DZ...ESP IN THE MORNING
ACROSS THE NRN MTNS...AND SE PA AIRFIELDS. IMPROVING CONDITIONS LATE.

SUN NIGHT...SCT RESTRICTIONS DUE TO FOG.

MON AND TUE...NO SIG WX.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ005-006-
010>012-017>019-025>028-037-041-042-045-046-049>053.

&&

$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR







AREA FORECAST DISCUSSION...UPDATED

NWS ABERDEEN SD

 1033 AM CDT FRI SEP 20 2013

.UPDATE...
ADJUSTED CLOUD COVER THIS MORNING. LATEST SATELLITE IMAGERY SHOWS
A SWATH OF STRATUS OVER THE EASTERN CWA. STILL EXPECT THIS TO
CLEAR OUT BY EARLY AFTERNOON. LOWERED TEMPERATURES TONIGHT A FEW
DEGREES ACROSS THE JAMES RIVER VALLEY AND BORDERING COUNTIES SINCE
RETURN FLOW LOOKS LIKE IT WILL BE DELAYED. WILL LIKELY NEED A FROST
ADVISORY OVER PARTS OF THE AREA TONIGHT BUT WILL WAIT FOR 12Z
MODELS BEFORE DETERMINING EXACT AREA OF CONCERN.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY
UPPER TROUGH AXIS IS CENTERED OVER THE DAKOTAS EARLY THIS MORNING
WITH A SMALLER INDIVIDUAL SHORTWAVE/VORT MAX SPINNING ACROSS
NORTHEAST SD. ISOLATED SPRINKLES/LIGHT SHOWERS HAVE BEEN OCCURRING
OVER THE PAST SEVERAL HOURS IN ASSOCIATION WITH THIS SMALLER VORT
MAX. HRRR PICKING UP ON THIS SOMEWHAT AND SHOWS THIS ACTIVITY
MOVING OUT OF THE AREA LATER THIS MORNING AS THE SHORTWAVE EXITS.
PLENTY OF STRATUS CLOUDS WITH THIS WAVE AS WELL. SOUNDINGS ACROSS
THE CWA SUGGEST MORE SUN THAN CLOUDS ACROSS THE WESTERN CWA
THROUGH THE DAY...BUT ACROSS THE EAST...STRATUS WILL TAKE SOME
TIME TO EXIT. AND WHATEVER STRATUS DOES EXIT OR DISSIPATE WILL
LIKELY BE FILLED BY CUMULUS DEVELOPMENT BY LATE MORNING OR EARLY
AFTERNOON. TEMPS WILL BE RATHER COOL ACROSS THE EASTERN CWA TODAY
WHERE TEMPS ALOFT ARE COLDEST. HIGHS IN THE 60S CAN BE EXPECTED
HERE.

SURFACE HIGH PRESSURE CENTERS ITSELF OVER THE REGION TONIGHT INTO
SATURDAY MORNING. THIS IS A COOL AIR MASS MOVING INTO THE AREA SO
WITH CLEARING SKIES AND LIGHT WINDS OVERNIGHT...LOOKING AT A
CHILLY START TO THE MORNING ON SATURDAY. MORNING LOWS IN THE 30S
ARE FORECAST FOR MOST OF THE EASTERN CWA...WITH THE JAMES VALLEY
LIKELY FALLING INTO THE MID 30S.

WARM AIR ADVECTION RAMPS BACK UP AGAIN SATURDAY INTO SUNDAY...WITH
WARMING TEMPERATURES AND INCREASING SOUTHEAST WINDS. BREEZY/WINDY
CONDITIONS LOOK LIKELY ON SUNDAY AS THE PRESSURE GRADIENT ACROSS
THE CWA BECOMES RATHER TIGHT.


.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY

THE LONG TERM SHOULD BE FAIRLY ACTIVE ACCORDING TO THE LATEST
MODELS. A SOMEWHAT PROGRESSIVE MID LEVEL FLOW IS ANTICIPATED WITH
ONE DECENT S/W TROF MOVING THROUGH SUNDAY NIGHT AND MONDAY. THIS
SHOULD BRING RAIN/THUNDER TO MUCH OF THE CWA...ALTHOUGH MOST
MODELS ARE MORE BULLISH WITH AMOUNTS OVER THE WESTERN CWA VS THE
EAST. THEN A FAIRLY DEEP TROF DIGS INTO THE WESTERN CONUS SETTING
UP SOUTHWEST FLOW ALOFT FOR THE LATTER PART OF NEXT WEEK. A
FRONTAL BOUNDARY WILL BE PARKED ACROSS THE AREA. RAIN CHANCES ARE
EXPECTED MAINLY BEHIND THE FRONT THROUGH THE PERIOD. THE MODELS DO
HAVE SOME DIFFERENCES ON THE STRENGTH OF S/W ENERGY AND SFC WAVES
RIDING THE FRONT...BUT AT THAT TIME RANGE THIS IS EXPECTED. OVERALL
TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD.


&&

.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

MVFR CIGS AND PATCHY DRIZZLE OVER THE EASTERN DAKOTAS WILL
DISSIPATE OR MOVE OFF TO THE EAST BEFORE NOON...LEAVING VFR
CONDITIONS REGION WIDE.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
UPDATE...WISE
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...WISE

WEATHER.GOV/ABERDEEN







SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.



 &&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY

UPPER TROUGH AXIS IS CENTERED OVER THE DAKOTAS EARLY THIS MORNING
WITH A SMALLER INDIVIDUAL SHORTWAVE/VORT MAX SPINNING ACROSS
NORTHEAST SD. ISOLATED SPRINKLES/LIGHT SHOWERS HAVE BEEN OCCURRING
OVER THE PAST SEVERAL HOURS IN ASSOCIATION WITH THIS SMALLER VORT
MAX. HRRR PICKING UP ON THIS SOMEWHAT AND SHOWS THIS ACTIVITY
MOVING OUT OF THE AREA LATER THIS MORNING AS THE SHORTWAVE EXITS.
PLENTY OF STRATUS CLOUDS WITH THIS WAVE AS WELL. SOUNDINGS ACROSS
THE CWA SUGGEST MORE SUN THAN CLOUDS ACROSS THE WESTERN CWA
THROUGH THE DAY...BUT ACROSS THE EAST...STRATUS WILL TAKE SOME
TIME TO EXIT. AND WHATEVER STRATUS DOES EXIT OR DISSIPATE WILL
LIKELY BE FILLED BY CUMULUS DEVELOPMENT BY LATE MORNING OR EARLY
AFTERNOON. TEMPS WILL BE RATHER COOL ACROSS THE EASTERN CWA TODAY
WHERE TEMPS ALOFT ARE COLDEST. HIGHS IN THE 60S CAN BE EXPECTED
HERE.

SURFACE HIGH PRESSURE CENTERS ITSELF OVER THE REGION TONIGHT INTO
SATURDAY MORNING. THIS IS A COOL AIR MASS MOVING INTO THE AREA SO
WITH CLEARING SKIES AND LIGHT WINDS OVERNIGHT...LOOKING AT A
CHILLY START TO THE MORNING ON SATURDAY. MORNING LOWS IN THE 30S
ARE FORECAST FOR MOST OF THE EASTERN CWA...WITH THE JAMES VALLEY
LIKELY FALLING INTO THE MID 30S.

WARM AIR ADVECTION RAMPS BACK UP AGAIN SATURDAY INTO SUNDAY...WITH
WARMING TEMPERATURES AND INCREASING SOUTHEAST WINDS. BREEZY/WINDY
CONDITIONS LOOK LIKELY ON SUNDAY AS THE PRESSURE GRADIENT ACROSS
THE CWA BECOMES RATHER TIGHT.

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY

THE LONG TERM SHOULD BE FAIRLY ACTIVE ACCORDING TO THE LATEST
MODELS. A SOMEWHAT PROGRESSIVE MID LEVEL FLOW IS ANTICIPATED WITH
ONE DECENT S/W TROF MOVING THROUGH SUNDAY NIGHT AND MONDAY. THIS
SHOULD BRING RAIN/THUNDER TO MUCH OF THE CWA...ALTHOUGH MOST
MODELS ARE MORE BULLISH WITH AMOUNTS OVER THE WESTERN CWA VS THE
EAST. THEN A FAIRLY DEEP TROF DIGS INTO THE WESTERN CONUS SETTING
UP SOUTHWEST FLOW ALOFT FOR THE LATTER PART OF NEXT WEEK. A
FRONTAL BOUNDARY WILL BE PARKED ACROSS THE AREA. RAIN CHANCES ARE
EXPECTED MAINLY BEHIND THE FRONT THROUGH THE PERIOD. THE MODELS DO
HAVE SOME DIFFERENCES ON THE STRENGTH OF S/W ENERGY AND SFC WAVES
RIDING THE FRONT...BUT AT THAT TIME RANGE THIS IS EXPECTED. OVERALL
TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD.

&&

.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

MVFR CIGS AND PATCHY DRIZZLE OVER THE EASTERN DAKOTAS WILL
DISSIPATE OR MOVE OFF TO THE EAST BEFORE NOON...LEAVING VFR
CONDITIONS REGION WIDE.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
UPDATE...TDK
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...TDK

WEATHER.GOV/ABERDEEN







AREA FORECAST DISCUSSION

NWS MEMPHIS TN

 1002 AM CDT FRI SEP 20 2013

.DISCUSSION...14Z SURFACE ANALYSIS PLACES A COLD FRONT FROM HUDSON
BAY BACK THROUGH EAST CENTRAL MISSOURI...ARKANSAS...WITH AN
EMBEDDED SURFACE LOW LOCATED OVER NORTHEAST TEXAS. TEMPERATURES AS
OF 9 AM CDT ARE IN THE 70S AT MOST LOCATIONS.

REGIONAL WSR-88D RADAR TRENDS INDICATE THE LEADING EDGE OF SHOWERS
AND THUNDERSTORMS ARE ALREADY ALONG AND WEST OF THE MISSISSIPPI
RIVER. SHORT TERM MODELS INCLUDING THE 3KM HRRR INDICATE A
POTENTIAL FOR RAIN ENDING EARLIER TONIGHT ALONG AND WEST OF THE
MISSISSIPPI RIVER. WILL MAKE ADJUSTMENTS TO AFTERNOON RAIN
CHANCES BASED ON CURRENT TRENDS AND CONSIDER TRIMMING CHANCES BACK
TONIGHT ACROSS THE ABOVE MENTIONED AREA AFTER THE 12Z GFS ARRIVES.

NOT ANTICIPATING ANY STRONG TO SEVERE THUNDERSTORM POTENTIAL AT
THIS TIME. HOWEVER...SUFFICIENT FORCING...PRECIPITABLE WATER VALUES
ABOVE 2 INCHES AND A SLOW MOVING FRONT STILL INDICATE A POTENTIAL
FOR HEAVY RAINFALL ACROSS THE MID SOUTH THROUGH TONIGHT. NOT
PLANNING ON ISSUING A FLASH FLOOD WATCH AT THIS TIME AS FLASH
FLOOD GUIDANCE VALUES STILL REMAIN HIGH DUE TO THE RECENT DRY
WEATHER AND ANTICIPATING AN AVERAGE OF RAINFALL UP TO 1-2 INCHES.

WILL MAKE ADJUSTMENTS TO ALL OTHER ELEMENTS AS NEEDED TO ACCOUNT
FOR SHORT TERM TRENDS.

UPDATED GRIDS WILL BE AVAILABLE SHORTLY.

CJC

&&

.PREV DISCUSSION... /ISSUED 624 AM CDT FRI SEP 20 2013/

UPDATE...
UPDATED FOR 12Z AVIATION DISCUSSION.

PREV DISCUSSION... /ISSUED 434 AM CDT FRI SEP 20 2013/

DISCUSSION...

CURRENTLY...A SIGNIFICANT MID LEVEL TROF IS PUSHING INTO THE UPPER
MS VALLEY WITH AN ASSOCD COLD FRONT STRETCHING FROM NEAR CHICAGO
SOUTHWEST INTO OKLAHOMA. ANOTHER PIECE OF UPPER LEVEL ENERGY IS
PUSHING FROM MEXICO INTO TEXAS WHICH IS HELPING TO FUNNEL DEEP
MOISTURE NORTHEASTWARD ALONG THE FRONT. RAIN WILL START PUSHING
INTO THE MIDSOUTH AT SUNRISE. TEMPS ARE VERY MILD ACROSS THE AREA
UNDER HIGH CLOUDS AND SOUTHERLY FLOW...IN THE UPPER 60S TO MID
70S.

TODAY THROUGH TONIGHT...THE MID LEVEL TROF ASSOCD WITH THE
NORTHERN BRANCH OF THE JET WILL PHASE WITH THE SOUTHERN STREAM
ENERGY COMING OUT OF TEXAS TO PRODUCE A HEAVY RAIN EVENT ACROSS
THE MIDSOUTH. DEEP MOISTURE WILL FLOW NORTHEASTWARD ALONG THE
SURFACE FRONT THAT WILL PUSH ACROSS THE AREA TODAY AND TONIGHT.
MODELS HAVE PRECIP WATER VALUES CLIMBING ABOVE 2 INCHES ALONG AND
AHEAD OF THE FRONT. MEANWHILE A WEAK SURFACE LOW WILL DEVELOP ALONG
THE FRONT AS IT PUSHES THROUGH THE MIDSOUTH. MODELS ARE INDICATING VERY
STRONG LIFT INVOF THE FRONT AS WELL. AS A RESULT EXPECT A WIDESPREAD
HEAVY RAINFALL OF 2 INCHES TO PERHAPS AS MUCH AS 4 INCHES LOCALLY
ACROSS THE AREA. DUE TO THE RECENT DRY SPELL RIVER LEVELS ARE LOW
AND FLASH FLOOD GUIDANCE VALUES ARE MAXED OUT SO WILL HOLD OFF ON
A FLASH FLOOD WATCH. WILL MENTION LOW LYING/LOCALIZED FLOODING IN
THE HWO. MARGINAL INSTABILITY COMBINED WITH WEAK SHEAR WILL KEEP
THE SEVERE WEATHER THREAT LOW. TEMPS WILL BE COOLER EVERYWHERE
EXCEPT NE MS WHERE RAIN WILL HOLD OFF FOR MUCH OF THE DAY AND
TEMPS WILL APPROACH 90. RAIN WILL BEGIN TO TAPER OFF FROM THE NW
LATER TONIGHT AS THE FRONT...MOISTURE AND LIFT PUSH EAST.

SATURDAY THROUGH MONDAY...NAM AND GFS PUSH THE FRONT THROUGH A FEW
HOURS QUICKER THAN THE ECMWF. AS A RESULT THE ECMWF HAS QUITE A
BIT MORE PRECIP OVER NE MS SATURDAY AM. TOOK A COMPROMISE
SOLUTION. OTHERWISE EXPECT CLEARING SKIES AND COOLER TEMPS UNDER
NORTHERLY WINDS. EXPECT BELOW NORMAL TEMPS FROM SATURDAY THROUGH
SUNDAY NIGHT WITH HIGHS IN THE UPPER 70S EACH DAY AND LOWS DEEP
INTO THE 50S EACH NIGHT. TEMPS WILL BEGIN TO WARM TOWARD
SEASONABLE LEVELS ON MONDAY AS HIGH PRESSURE RETREATS.

MONDAY NIGHT THROUGH TUESDAY NIGHT...PERFORMED MAJOR SURGERY ON
THIS PART OF THE FORECAST. THE OPERATIONAL GFS AND ECMWF BOTH PUSH
A MID LEVEL TROF THROUGH THE REGION THAT PICKS UP A GOOD DEAL OF
MOISTURE FROM THE GULF AND SPREADS RAIN INTO THE MIDSOUTH MONDAY
NIGHT THROUGH TUESDAY NIGHT. GIVEN THE AGREEMENT BETWEEN THE TWO
MODELS AND THE CONFIRMATION FROM THE GFS ENSEMBLES IT IS HARD TO
IGNORE THIS FEATURE. ADDED SLIGHT CHC/CHC POPS DURING THIS PERIOD
FOR A START THOUGH THESE MAY NEED TO BE INCREASED. THIS FEATURE
WILL ALSO KEEP HIGH TEMPS DOWN A FEW DEGREES FROM THE PREVIOUS
FORECAST.

WEDNESDAY AND THURSDAY...UPPER LEVEL RIDGING WILL PUSH INTO THE
MIDSOUTH FROM THE WEST AND TEMPS WILL CLIMB BACK ABOVE NORMAL WITH
LITTLE RAIN.

SJM

&&

.AVIATION...
VFR CONDS TO START OFF THIS TAF PERIOD...BUT CONDITIONS WILL
DETERIORATE THIS MORNING AT JBR AND MEM...AND THEN THIS AFTERNOON
FOR MKL AND TUP...AS BOTH CIGS/VIS DROP TO MVFR/IFR. BELIEVE ANY
LIFR/VLIFR CONDITIONS WILL BE VERY BRIEF AND NOT PREDOMINATE. A LARGE
SWATH OF SHOWERS WITH EMBEDDED THUNDERSTORMS ARE EXPECTED ALONG A
COLD FRONT...WITH RAIN HEAVY AT TIMES.

SOUTH TO SOUTHWEST WINDS AT 5-8KTS WILL VEER WEST AND EVENTUALLY NORTH
WITH THE FRONTAL PASSAGE.

JAB

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  83  63  79  58 / 100 100  10   0
MKL  84  62  77  50 /  80 100  10  10
JBR  80  59  77  52 / 100  60  10   0
TUP  89  67  79  56 /  60 100  40  10

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

$$








AREA FORECAST DISCUSSION...UPDATED

NWS MORRISTOWN TN

 1029 AM EDT FRI SEP 20 2013

.DISCUSSION...
THE MAIN FORECAST ISSUE OF THE DAY IS WHETHER CONVECTION WILL
DEVELOP THIS AFTERNOON OVER NE PORTIONS OF THE AREA. THE 12Z OHX
SOUNDING SHOWS A LITTLE MIDLEVEL CAPE...AND RUC AND NAM FORECAST
SOUNDINGS SHOW A -3 TO -4 LI THIS AFTERNOON AT TRI. AS IS TYPICALLY
THE CASE...THE GFS FORECAST SOUNDING IS MORE STABLE. FORCING WILL
BE LACKING BUT THERE WILL BE SOME LOW LEVEL MOISTURE TO WORK WITH.
THE CURRENT FORECAST OF SCATTERED TO ISOLATED POPS APPEARS
REASONABLE WITH NO COMPELLING EVIDENCE TO WARRANT A CHANGE. TEMPS
APPEAR ON TRACK AS WELL AND IN LINE WITH THE LATEST GUIDANCE...SO
NO UPDATE WILL BE NEEDED.

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.

&&

$$

DGS











AREA FORECAST DISCUSSION...CORRECTED

NWS PUEBLO CO

 338 PM MDT FRI SEP 20 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 331 PM MDT FRI SEP 20 2013

QUIET WEATHER OVER THE AREA TODAY BENEATH TRANSIENT UPPER RIDGE.
STRATUS HAS CLEARED OUT OF MOST OF THE SE PLAINS...THOUGH COOLER AIR
MASS OVER THE REGION HAS KEPT SE PLAINS CAPPED.  STILL WAITING TO
SEE IF SUFFICIENT HEATING WILL OCCUR TO POP A THUNDERSTORM OR TWO
ALONG THE CREST OF THE SOUTHERN SANGRES...AND PERHAPS ACROSS THE
EASTERN SAN JUAN MOUNTAINS...BUT SO FAR CONVECTION HAS HAD A HARD
TIME GETTING GOING...WITH AIRMASS LOOKING TOO DRY ACROSS THE SW MTS
WHERE DEW POINTS HAVE DROPPED INTO THE 20S...AND TOO CAPPED AND COOL
FOR THE SOUTHERN SANGRES.  EACH SUCCESSIVE HRRR RUN HAS BACKED OFF
WITH QPF FOR THOSE AREAS...SO HAVE TRIMMED BACK POPS INTO THE SILENT
CATEGORY.

SOUTHWEST FLOW INCREASES OVER THE AREA FOR SUNDAY.  NAM12 PICKS UP
SOME LOW LEVEL MOISTURE AND GENERATES SOME OROGRAPHIC SHOWERS ACROSS
THE SOUTHWEST MTS EARLY SATURDAY MORNING.  THIS COULD BE A BIT
OVERDONE...BUT GFS HINTS AT THIS TOO SO WILL MAINTAIN SOME ISOLATED
SHOWERS FOR THAT AREA.  BY AFTERNOON...MODELS SHOW SOME ISOLATED
THUNDERSTORMS SPREADING NORTH AND EASTWARD INTO THE SAWATCH AND
MOSQUITO RANGES AND THE SANGRES.  OTHERWISE...TEMPERATURES SHOULD
REBOUND NICELY BACK INTO THE 80S FOR THE SE PLAINS WITH A MIX OF 60S
AND 70S FOR THE MOUNTAIN AREAS.  SOUTHERLY WINDS WILL INCREASE
ACROSS THE AREA AS THE LEE TROF DEEPENS AHEAD OF THE NEXT
APPROACHING TROF.  STRONGEST WINDS WILL BE ACROSS THE HIGHER PEAKS
IN THE AFTERNOON AND ALONG THE FAR EASTERN BORDER ON THE EAST SIDE
OF THE SFC TROF AXIS.  BOTH AREAS COULD SEE GUSTS IN THE 25-30 KT
RANGE.  -KT


.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 331 PM MDT FRI SEP 20 2013

.SATURDAY NIGHT THROUGH SUNDAY NIGHT...TROUGH MOVES ACROSS THE
REGION SUNDAY AFTERNOON AND EVENING. MODELS HAVE SOME DIFFERENCES
ON THE STRENGTH OF THE TROUGH. THE NAM IS THE WEAKEST WHILE THE EC
IS THE STRONGEST. MAIN CONCERNS WITH TROUGH PASSAGE WOULD BE SNOW
LEVELS ALONG THE CONTINENTAL DIVIDE AND WINDS OVER THE EASTERN
MOUNTAINS AND PLAINS. MOST OF THE PRECIPITATION OVER THE
CONTINENTAL DIVIDE REGION OCCURS AHEAD OF THE COLDEST AIR
ALOFT...AND SNOW IS MOSTLY LIMITED TO THE HIGHEST PEAKS. SNOW
LEVELS COULD FALL BELOW TREE LINE BEFORE PRECIPITATION ENDS FOR
SOME ACCUMULATIONS. IF THE TROUGH IS DEEPER...MORE SNOW COULD FALL
BELOW TREE LINE. THE BEST CHANCES FOR SNOW BELOW TREELINE WILL BE
SUNDAY EVENING. SECOND CONCERN WILL BE WINDS. GUSTY SOUTH TO
SOUTHWEST WINDS WILL DEVELOP AHEAD OF THE TROUGH SUNDAY ON THE
PLAINS. GFS AND EC HAVE THE 500MB TROUGH CUT OFF BRIEFLY AS IT
LIFTS NORTHEAST INTO NEBRASKA. HAVE SOME CONCERNS FOR A BRIEF
PERIOD OF STRONG WINDS SUNDAY EVENING OVER THE EASTERN MOUNTAINS
AND INTERSTATE 25 CORRIDOR. MODELS DO NOT HAVE STRONG WINDS AT
THIS TIME...BUT HAVE SEEN WINDY CONDITIONS WITH SIMILAR PATTERNS.

.MONDAY THROUGH WEDNESDAY...DRY AND WARM PATTERN DEVELOPS BEHIND
DEPARTING TROUGH AND AHEAD OF THE NEXT TROUGH. BREEZY TO WINDY
CONDITIONS ARE POSSIBLE ON WEDNESDAY AS SOUTHWEST FLOW ALOFT
STRENGTHENS AHEAD OF THE NEXT TROUGH MOVING INTO THE PACIFIC
NORTHWEST.

.THRUSDAY AND FRIDAY...EC AND GFS HAVE THE TROUGH OVER THE
NORTHWEST US MOVING NORTHEASTWARD ACROSS THE NORTHERN ROCKIES.
REGION WILL BE ON THE SOUTHERN END OF THE TROUGH. BOTH MODELS
SUGGEST A COLD FRONT IN THE REGION...WITH THE POTENTIAL FOR SOME
UPSLOPE ON THE EASTERN PLAINS. TOO EARLY TO GET VERY SPECIFIC ON
DETAILS SUCH AS THE LOCATION OF THE FRONT...STRENGTH OF EASTERLY
UPSLOPE FLOW AND STRENGTH OF THE TROUGH. GRIDS HAVE A MODEST
COOLING TREND WITH SOME ISOLATED POPS. --PGW--


&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 331 PM MDT FRI SEP 20 2013

VFR CONDITIONS EXPECTED AT TAF SITES THROUGH THE NIGHT
WITH PATCHY REMNANT CLOUD COVER AROUND KCOS DISSIPATING BY 00Z.
EXPECT CLEAR SKIES OVERNIGHT THOUGH KALS COULD SEE A RETURN OF SOME
PATCHY GROUND FOG TOWARDS 12Z.  FOR NOW HAVE KEPT VIS IN THE MVFR
CATEGORY FOR A COUPLE HOURS AROUND SUNRISE...BUT VIS COULD VERY WELL
DROP INTO THE IFR RANGE IF SKIES REMAIN SUFFICIENT CLEAR.
OTHERWISE...VFR CONDITIONS WILL CONTINUE INTO SATURDAY WITH WINDS
INCREASING FROM THE SOUTH DURING THE AFTERNOON WITH SPEEDS 10-15
KTS.  -KT

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...KT
LONG TERM...PGW
AVIATION...KT









AREA FORECAST DISCUSSION

NWS PUEBLO CO

 332 PM MDT FRI SEP 20 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 331 PM MDT FRI SEP 20 2013

UIET WEATHER OVER THE AREA TODAY BENEATH TRANSIENT UPPER RIDGE.
STRATUS HAS CLEARED OUT OF MOST OF THE SE PLAINS...THOUGH COOLER AIR
MASS OVER THE REGION HAS KEPT SE PLAINS CAPPED.  STILL WAITING TO
SEE IF SUFFICIENT HEATING WILL OCCUR TO POP A THUNDERSTORM OR TWO
ALONG THE CREST OF THE SOUTHERN SANGRES...AND PERHAPS ACROSS THE
EASTERN SAN JUAN MOUNTAINS...BUT SO FAR CONVECTION HAS HAD A HARD
TIME GETTING GOING...WITH AIRMASS LOOKING TOO DRY ACROSS THE SW MTS
WHERE DEW POINTS HAVE DROPPED INTO THE 20S...AND TOO CAPPED AND COOL
FOR THE SOUTHERN SANGRES.  EACH SUCCESSIVE HRRR RUN HAS BACKED OFF
WITH QPF FOR THOSE AREAS...SO HAVE TRIMMED BACK POPS INTO THE SILENT
CATEGORY.

SOUTHWEST FLOW INCREASES OVER THE AREA FOR SUNDAY.  NAM12 PICKS UP
SOME LOW LEVEL MOISTURE AND GENERATES SOME OROGRAPHIC SHOWERS ACROSS
THE SOUTHWEST MTS EARLY SATURDAY MORNING.  THIS COULD BE A BIT
OVERDONE...BUT GFS HINTS AT THIS TOO SO WILL MAINTAIN SOME ISOLATED
SHOWERS FOR THAT AREA.  BY AFTERNOON...MODELS SHOW SOME ISOLATED
THUNDERSTORMS SPREADING NORTH AND EASTWARD INTO THE SAWATCH AND
MOSQUITO RANGES AND THE SANGRES.  OTHERWISE...TEMPERATURES SHOULD
REBOUND NICELY BACK INTO THE 80S FOR THE SE PLAINS WITH A MIX OF 60S
AND 70S FOR THE MOUNTAIN AREAS.  SOUTHERLY WINDS WILL INCREASE
ACROSS THE AREA AS THE LEE TROF DEEPENS AHEAD OF THE NEXT
APPROACHING TROF.  STRONGEST WINDS WILL BE ACROSS THE HIGHER PEAKS
IN THE AFTERNOON AND ALONG THE FAR EASTERN BORDER ON THE EAST SIDE
OF THE SFC TROF AXIS.  BOTH AREAS COULD SEE GUSTS IN THE 25-30 KT
RANGE.  -KT


.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 331 PM MDT FRI SEP 20 2013

.SATURDAY NIGHT THROUGH SUNDAY NIGHT...TROUGH MOVES ACROSS THE
REGION SUNDAY AFTERNOON AND EVENING. MODELS HAVE SOME DIFFERENCES
ON THE STRENGTH OF THE TROUGH. THE NAM IS THE WEAKEST WHILE THE EC
IS THE STRONGEST. MAIN CONCERNS WITH TROUGH PASSAGE WOULD BE SNOW
LEVELS ALONG THE CONTINENTAL DIVIDE AND WINDS OVER THE EASTERN
MOUNTAINS AND PLAINS. MOST OF THE PRECIPITATION OVER THE
CONTINENTAL DIVIDE REGION OCCURS AHEAD OF THE COLDEST AIR
ALOFT...AND SNOW IS MOSTLY LIMITED TO THE HIGHEST PEAKS. SNOW
LEVELS COULD FALL BELOW TREE LINE BEFORE PRECIPITATION ENDS FOR
SOME ACCUMULATIONS. IF THE TROUGH IS DEEPER...MORE SNOW COULD FALL
BELOW TREE LINE. THE BEST CHANCES FOR SNOW BELOW TREELINE WILL BE
SUNDAY EVENING. SECOND CONCERN WILL BE WINDS. GUSTY SOUTH TO
SOUTHWEST WINDS WILL DEVELOP AHEAD OF THE TROUGH SUNDAY ON THE
PLAINS. GFS AND EC HAVE THE 500MB TROUGH CUT OFF BRIEFLY AS IT
LIFTS NORTHEAST INTO NEBRASKA. HAVE SOME CONCERNS FOR A BRIEF
PERIOD OF STRONG WINDS SUNDAY EVENING OVER THE EASTERN MOUNTAINS
AND INTERSTATE 25 CORRIDOR. MODELS DO NOT HAVE STRONG WINDS AT
THIS TIME...BUT HAVE SEEN WINDY CONDITIONS WITH SIMILAR PATTERNS.

.MONDAY THROUGH WEDNESDAY...DRY AND WARM PATTERN DEVELOPS BEHIND
DEPARTING TROUGH AND AHEAD OF THE NEXT TROUGH. BREEZY TO WINDY
CONDITIONS ARE POSSIBLE ON WEDNESDAY AS SOUTHWEST FLOW ALOFT
STRENGTHENS AHEAD OF THE NEXT TROUGH MOVING INTO THE PACIFIC
NORTHWEST.

.THRUSDAY AND FRIDAY...EC AND GFS HAVE THE TROUGH OVER THE
NORTHWEST US MOVING NORTHEASTWARD ACROSS THE NORTHERN ROCKIES.
REGION WILL BE ON THE SOUTHERN END OF THE TROUGH. BOTH MODELS
SUGGEST A COLD FRONT IN THE REGION...WITH THE POTENTIAL FOR SOME
UPSLOPE ON THE EASTERN PLAINS. TOO EARLY TO GET VERY SPECIFIC ON
DETAILS SUCH AS THE LOCATION OF THE FRONT...STRENGTH OF EASTERLY
UPSLOPE FLOW AND STRENGTH OF THE TROUGH. GRIDS HAVE A MODEST
COOLING TREND WITH SOME ISOLATED POPS. --PGW--


&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 331 PM MDT FRI SEP 20 2013

VFR CONDITIONS EXPECTED AT TAF SITES THROUGH THE NIGHT
WITH PATCHY REMNANT CLOUD COVER AROUND KCOS DISSIPATING BY 00Z.
EXPECT CLEAR SKIES OVERNIGHT THOUGH KALS COULD SEE A RETURN OF SOME
PATCHY GROUND FOG TOWARDS 12Z.  FOR NOW HAVE KEPT VIS IN THE MVFR
CATEGORY FOR A COUPLE HOURS AROUND SUNRISE...BUT VIS COULD VERY WELL
DROP INTO THE IFR RANGE IF SKIES REMAIN SUFFICIENT CLEAR.
OTHERWISE...VFR CONDITIONS WILL CONTINUE INTO SATURDAY WITH WINDS
INCREASING FROM THE SOUTH DURING THE AFTERNOON WITH SPEEDS 10-15
KTS.  -KT

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...KT
LONG TERM...PGW
AVIATION...KT







AREA FORECAST DISCUSSION

NWS CHICAGO/ROMEOVILLE IL

 1258 PM CDT FRI SEP 20 2013

.DISCUSSION...
1105 AM CDT

A SHORT WAVE TRACKED NORTHEASTWARD FROM WEST CENTRAL IL TO FAR
SOUTHWESTERN LOWER MI DURING THE LATE OVERNIGHT AND THE EARLY TO
MID MORNING HOURS. WHILE THE AXIS OF THE MAIN UPPER TROUGH IS
STILL UPSTREAM OVER THE UPPER MIDWEST...UPPER MS AND MID MO
VALLEYS...SUBSIDENCE AND DRYING IN THE MID LEVELS HAS RESULTED IN
AND END OF ANY SHOWERS...EXCEPT FOR A LINGERING SPRINKLE OR TWO
IN THE FAR SOUTHEASTERN PORTION OF THE FORECAST AREA.

A PRE-FRONTAL TROUGH ASSOCIATED WITH THE SHORT WAVE HAD ALREADY
VEERED WINDS TO WEST-SOUTH AND WESTERLY DURING THE FIRST PART OF
THE MORNING...WITH THE COLD FRONT AT LATE MORNING MOVING INTO
SOUTH CENTRAL WI AND NORTH CENTRAL IL AS WELL AS WEST CENTRAL IL.

BENEATH THE RAIN-ENDING MID LEVEL SUBSIDENCE THE LOW LEVEL
MOISTURE REMAINED HIGH WITH WIDESPREAD LOW...THICK STRATOCUMULUS
ACROSS THE AREA THOUGH THERE ARE SIGNS OF HOPE. AS THE COLD FRONT
CONTINUES TO PUSH FURTHER EASTWARD ACROSS FORECAST LATE THIS
MORNING AND THIS AFTERNOON IT WILL USHER IN DRIER LOW LEVEL AIR.
EXPECT TO SEE THE TREND IN SCATTERING OUT THE LOWER CLOUDS WEST TO
EAST TON CONTINUE AS THE AFTERNOON PROGRESSES ALTHOUGH THERE WILL
STILL BE A CIRRUS-STRATUS DECK OVER THE AREA AS THE UPPER TROUGH
IS PROGGED TO REMAIN WEST OF THE AREA...NOT MOVING OVER
SOUTHWESTERN WI AND NORTHWESTERN IL UNTIL MID TO LATE THIS
EVENING.

DO NOT FORESEE THE AREA OF STRATOCUMULUS SPREADING SOUTHEASTWARD
ACROSS NORTHERN IA AND WEST CENTRAL WI LATE THIS MORNING REACHING
THE LOCAL AREA UNTIL THIS EVENING GIVEN THE SLOW PROGRESSION OF
THE UPPER TROUGH AND HIGHER RESOLUTION MODEL RH FORECASTS IN THE
1-2.5K FT AGL LAYER KEEPING THIS AREA OF HIGHER LOW LEVEL
MOISTURE TO OUR NORTHWEST THROUGH THE REST OF THE DAY.

STRONG LOW LEVEL COLD AIR ADVECTION UNDERWAY AND WILL CONTINUE
TODAY AND TONIGHT. BASED ON UPSTREAM CONDITIONS HAVE DROPPED MAX
TEMPS FOR TODAY ACROSS THE FORECAST AREA A FEW DEGREES THOUGH A
BIT TRICKY AS IF CIRRUS THINS ENOUGH AFTER THE STRATOCUMULUS
CLEARS OUT THERE MAY BE A SLIGHT REBOUND IN THE WESTERN COUNTIES
UNTIL THE HEATING IS NEGATED BY THE COLD AIR ADVECTION.

TRS

//PREV DISCUSSION...
358 AM CDT

FORECAST CONCERNS ARE MAINLY FOCUSED ON THE NEAR TERM TODAY...AS  A
COLD FRONT PUSHES STEADILY EAST ACROSS THE FORECAST AREA. SPOTTY
PRECIP WILL END WITH THE PASSAGE OF THE FRONT...WITH BREEZY...DRY AN
COOLER WEATHER ARRIVING AS WE HEAD INTO THE WEEKEND.

SURFACE LOW PRESSURE WAS CONSOLIDATING NORTH OF LAKE SUPERIOR EARLY
THIS MORNING...WITH A COLD FRONT TRAILING SOUTHWARD ACROSS WISCONSIN
AND INTO FAR EASTERN IOWA AT 08Z. RELATIVELY COMPLEX UPPER PATTERN
WAS EVIDENT FROM RADAR/WATER VAPOR IMAGERY...WITH SEVERAL SMALLER
SCALE CIRCULATIONS ROTATING THROUGH BASE OF UPPER TROUGH PROPAGATING
EAST ACROSS THE UPPER MIDWEST. AREA OF THUNDERSTORMS WHICH HAD MOVED
INTO THE FORECAST AREA LATE LAST HAD DECREASED IN COVERAGE IN THE
WAKE OF AN MCV NOTED LIFTING ACROSS SOUTHEAST WISCONSIN AND WITH
STABILIZATION OF THE NOCTURNAL BOUNDARY LAYER. A FEW SCATTERED
STORMS CONTINUED FROM NEAR KALAMAZOO MICHIGAN TO NEAR DANVILLE AND
ST LOUIS...WHERE SPC/RAP ANALYSIS INDICATES WESTERN PERIPHERY OF
1000-2000 J/KG MUCAPE AXIS.  FARTHER WEST...AN AREA OF WEAKER
SHOWERS/LIGHT RAIN WAS NOTED ALONG THE LOW LEVEL FRONTAL BOUNDARY.
HIGH-RES GUIDANCE INDICATES THE CLUSTER OF SHOWERS AND THUNDERSTORMS
IN THE ST LOUIS/DOWNSTATE IL AREA WILL LIFT NORTHEAST THROUGH THIS
MORNING...AFFECTING MAINLY OUR SOUTHEAST COUNTIES. SCATTERED SHOWERS
ARE EXPECTED ELSEWHERE...ENDING WITH COLD FROPA LATER THIS MORNING
ACROSS NORTH CENTRAL ILLINOIS AND BY EARLY AFTERNOON ACROSS
NORTHEAST IL. FORECAST SOUNDINGS DEPICT SUBSTANTIAL DRYING
DEVELOPING IN THE 850-500 MB LAYER BEHIND THE COLD FRONT...WHICH IS
EVENTUALLY PROGGED TO CLEAR THE SOUTHEAST PART OF THE CWA VERY LATE
THIS AFTERNOON/EARLY THIS EVENING. NOT EXPECTING A LARGE TEMP SPREAD
DESPITE COLD FROPA ACROSS THE CWA TODAY...AS CLOUDS WILL HELP LIMIT
READINGS AHEAD OF THE FRONT.

UPPER TROUGH CONTINUES TO DEEPEN OVERHEAD AS IT MOVES SLOWLY EAST OF
THE AREA LATER TONIGHT AND SATURDAY. STRONG COOL ADVECTION DEVELOPS
AS WINDS SHIFT NORTH-NORTHWEST DURING THE PERIOD...WITH MODEL 850 MB
TEMPS FALLING TO AROUND +4C ON SATURDAY. THIS SHOULD LIMIT TEMPS
GENERALLY TO THE MID-UPPER 60S THROUGH THE WEEKEND DESPITE A GOOD
DEAL OF SUNSHINE...WITH SLIGHTLY COOLER TEMPS NEAR LAKE MICHIGAN
SUNDAY AS WINDS TURN ONSHORE FROM THE NORTHEAST. OVERNIGHT TEMPS
WILL COOL OFF CONSIDERABLY AS WELL...ESPECIALLY SUNDAY NIGHT AS THE
SURFACE HIGH PRESSURE RIDGE AXIS SPREADS INTO WISCONSIN AND ILLINOIS
AND ALLOWS FOR STRONG RADIATIONAL COOLING. HAVE UNDERCUT GUIDANCE IN
OUR TYPICALLY COOLER LOCATIONS SUNDAY MORNING...WITH SOME UPPER 30S
LIKELY WEST OF THE FOX RIVER VALLEY IN NORTH CENTRAL IL. COULD SEE
SOME LAKE EFFECT CLOUDS ACROSS NORTHEAST ILLINOIS/NORTHWEST INDIANA
SUNDAY MORNING AS LOW LEVEL WINDS BECOME NORTH-NORTHEAST.

LOOKS LIKE A DRY PERIOD WITH A MODERATION IN TEMPERATURES INTO NEXT
WEEK...AS HIGHLY AMPLIFIED UPPER PATTERN SLOWLY SHIFTS EAST. THIS
BRINGS UPPER RIDGE ACROSS THE AREA INTO MONDAY WITH THE SURFACE HIGH
DRIFTING OFF TO THE EAST. LONGER RANGE GUIDANCE INDICATES A SHORT
WAVE PUSHING INTO THE RIDGE ACROSS THE AREA TUESDAY...BUT WITH
LITTLE MOISTURE RETURN THANKS TO SOUTHEAST LOW LEVEL WINDS WEST OF
THE AFOREMENTIONED SURFACE HIGH. ECMWF/GFS BOTH SIMILAR IN
RE-BUILDING UPPER RIDGE ACROSS THE AREA IN THE WAKE OF THE SHORT
WAVE BY MID-WEEK. THIS WOULD SUPPORT TEMPS RISING BACK THROUGH THE

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* MVFR CIGS ARND 1000-1400FT AGL...SLOWLY LIFTING AFT 20Z.
* WEST WINDS ARND 10-14KT WITH GUSTS INCREASING TO 20KT AFT 20Z.
* WINDS SLOWLY TURNING NW/N AFT 23Z.

BEACHLER

//DISCUSSION...UPDATED 18Z...

FRONTAL BOUNDARY STRETCHES FROM GYY SOUTH THROUGH IKK AT 18Z.
WIND SHIFT TO THE WEST BEHIND THIS BNDRY. VISIBLE IMAGERY
CONTINUES TO INDICATE CONSIDERABLE CLOUDS WITH CIGS SLOW TO
IMPROVE...HOWEVER THEY HAVE COME UP TO ARND 1800-2000FT AGL. SKIES
ARE THINNING FURTHER BEHIND THE BOUNDARY...AND EXPECT THAT WITH
ADDTL HEATING THIS WILL ALLOW INCREASED WIND SPEEDS/GUSTS TO
20-24KT AND WILL HELP TO LIFT CIGS FURTHER. EXPECT CLOUDS TO
LINGER ARND 3-4KFT AGL THRU SUNSET THEN SLOWLY ERODE AFT 03Z. BY
08-10Z SKIES SHOULD ALMOST BECOME CLEAR WITH JUST A CIRRUS SHIELD
OVERHEAD. WINDS WILL CONTINUE TO TURN NORTH/NORTHWEST. AFT 16Z SAT
WINDS WILL BEGIN TO INCREASE YET AGAIN FROM THE NORTH/NORTHWEST
WITH GUSTS IN THE MID TO UPPER TEENS THRU MUCH OF MIDDAY AND
AFTERNOON HOURS. A SCT DECK OF CLOUDS SHOULD DEVELOP BY 18Z AND
MAY FOR A PERIOD OF TIME BECOME BKN EARLY IN THE AFTN. OTHERWISE
EXPECT IT TO REMAIN SCT WITH BASES ARND 3KFT AGL.

BEACHLER


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN MVFR CIGS THRU 20Z...MEDIUM CONFIDENCE IN
  PRECISE TIMING OF IMPROVING CIGS.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* MEDIUM/HIGH CONFIDENCE IN TIMING OF WINDS TURNING NW/N.

BEACHLER

//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...

* SATURDAY NIGHT...MVFR CIGS POSSIBLE.
* SUNDAY THROUGH THURSDAY...DRY/VFR.

&&

.MARINE...

310 AM...LOW PRESSURE OVER ONTARIO WILL MOVE NORTHEAST TODAY AND
TONIGHT AS IT DEEPENS WITH A TRAILING COLD FRONT MOVING ACROSS
LAKE MICHIGAN LATER THIS MORNING...TURNING WINDS WESTERLY. AS
COLDER AIR SPREADS ACROSS THE REGION THIS EVENING...WINDS WILL
TURN NORTHWESTERLY AND INCREASE IN SPEED WITH A SHORT DURATION OF
30 KTS POSSIBLE. SPEEDS WILL RELAX BACK INTO THE 15-25KT RANGE
OVERNIGHT INTO SATURDAY MORNING AND THEN DIMINISH FURTHER SATURDAY
NIGHT INTO SUNDAY MORNING AS A LARGE RIDGE OF HIGH PRESSURE SLOWLY
PASSES ACROSS THE LAKES REGION SUNDAY AND SUNDAY NIGHT. THIS HIGH
IS EXPECTED TO REMAIN OVER NEW ENGLAND...MID ATLANTIC AND EASTERN
LAKES INTO THE MIDDLE OF NEXT WEEK...ALLOWING FOR SOUTHEAST TO
SOUTHERLY FLOW OVER THE LAKE FROM SUNDAY NIGHT THROUGH THURSDAY.
CMS

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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Area Forecast Discussion
National Weather Service Lincoln IL
1251 PM CDT Fri Sep 20 2013

.DISCUSSION...
ISSUED 859 AM CDT Fri Sep 20 2013

14z/9am surface analysis shows cold front along the Illinois
River...with scattered light showers ahead of it across much of
the KILX CWA. Based on speed of front and current stability
parameters...think threat for thunder is over for the western half
of the area. Further east, HRRR suggests some re-development
across east-central and southeast Illinois during the afternoon.
Have made a quick update to the forecast to lower POPs and drop
thunder mention along and west of I-55. Will maintain likely POPs
for showers and thunderstorms further east, mainly along and east
of I-57. Zone update has already been sent.



&&

.AVIATION...
ISSUED 1251 PM CDT Fri Sep 20 2013

Line of showers is beginning to develop ahead of an advancing cold
front from near KTIP to KSPI. Based on radar timing tools, have
included a tempo group for showers between 18z and 20z at both
KDEC and KCMI. Once these showers pass east of the terminals, MVFR
ceilings will persist for a couple of hours before clouds
gradually begin to dissipate. Skies will become mostly clear by
early this evening, while low clouds associated with upper low
over northern/central Iowa track eastward and remain just north of
central Illinois. Winds will initially be from the W/SW ahead of
the front early this afternoon, then will become W/NW behind the
boundary later this afternoon through Saturday morning.

Barnes
&&

.PREV DISCUSSION...
ISSUED 322 AM CDT Fri Sep 20 2013
Deep upper trof moving across the Northern Plains and into the
Great Lake region...with the associated sfc low centered just
north of Lake Superior. Cold front draped through WI IA MO and
into the Southern Plains...lingering to the west along the Miss
River Valley this morning. Prefrontal showers and thunderstorms
from last night lingering in the east...weakened considerably in
the absence of an abundance of instability. First and main issue
for the forecast is the recharging of the atmosphere ahead of the
boundary in the warm sector this morning and the chances for
refire in the afternoon in the southeastern CWA. Beyond that,
Midwest gets into another dry period with heat building back into
the western CONUS and spreading into Central Illinois.

SHORT TERM...Today and tomorrow...
Scattered showers and thunderstorms throughout the day with the
best chances in the east this morning with remnant activity from
the overnight hours. Cold front still to the west will have the
chance to refire this afternoon. Exact location of the showers and
thunderstorms, as well as the strength, will be entirely dependent
on the speed of the advancing front, and any pockets of sunshine
that may enhance sfc based instability. At this point, however,
the front is moving through quickly and the precip may end up
wrapping up even sooner than midnight in the southeast. Cooler
temps tonight...somewhat inhibited by cloud cover anticipated.
Concern remains that more rapid clearing may result in a needed
adjustment. Tomorrow begins an extended dry period with sunny
skies and max temps in the lower 70s...light northerly winds as
high pressure begins to build back into the region.

LONG TERM...Sunday through Thursday...
Milder weather and dry through the extended. High pressure
dominates the eastern half of the country and temperatures remain
milder and closer to normal at first...with heat slowly building
again under a thermal ridge in the southwestern US. With
southwesterly flow kicking in next week Tues, the extended could
see some warmer temps as time draws nearer should the pattern
persist. Guidance is starting to respond and climb into the upper
70s/near 80 by mid week.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








AREA FORECAST DISCUSSION

NWS QUAD CITIES IA IL

 1255 PM CDT FRI SEP 20 2013

.UPDATE...
ISSUED AT 1250 PM CDT FRI SEP 20 2013

THE LOW CLOUDS HAVE ARRIVED IN THE CWFA AND SATELLITE TRENDS
INDICATE THEY SHOULD OVERSPREAD THE NORTHERN HALF OF THE CWFA
DURING THE AFTERNOON. CLOUD COVER WILL THUS HOLD TEMPERATURES DOWN
AND HIGHS HAVE BEEN LOWERED.

ISOLATED SPRINKLES ARE ALSO BEING REPORTED UNDER THE WRAP AROUND
CLOUDS SO THOSE WERE ADDED FOR THE AFTERNOON/EARLY EVENING HOURS.

CLEARING IS EXPECTED TO DEVELOP LATE THIS EVENING AND CONTINUE
OVERNIGHT WITH MAINLY CLEAR SKIES EXPECTED AROUND SUNRISE
SATURDAY.                        ..08..

UPDATE ISSUED AT 952 AM CDT FRI SEP 20 2013

CLOUD COVER IS PERSISTING LONGER THAN PREVIOUSLY THOUGHT. BASED ON
SATELLITE TRENDS...THICK HIGH CLOUDS SHOULD PERSIST FOR A MAJORITY
OF THE DAY. THE HIGH CLOUDS SHOULD SLOWLY THIN THIS AFTERNOON
ALLOWING MORE SUN TO BE SEEN.                ..08..

&&

.SYNOPSIS...
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN AREA OF SHOWERS AND THUNDERSTORMS HAS PUSHED TO EAST OF THE
DVN CWA THIS MORNING AHEAD OF THE PREFRONTAL TROUGH OVER EASTERN
IOWA AND THE COLD FRONT STRETCHES FROM CENTRAL LAKE SUPERIOR
SOUTHWARD THROUGH SOUTHEASTERN MINNESOTA AND CENTRAL IOWA AT THIS
TIME. SCATTERED SHOWERS AND LOW CEILINGS HAVE DEVELOPED ALONG THE
PREFRONTAL TROUGH THIS MORNING ASSOCIATED WITH THE CONVERGENCE ALONG
IT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 327 AM CDT FRI SEP 20 2013

THE MAIN FORECASTS CONCERNS THIS MORNING WILL BE THE SCATTERED
SHOWERS ALONG THE PREFRONTAL TROUGH AND THE LOW CEILINGS.

THE MAIN AREA OF PRECIPITATION HAS MOVED INTO EASTERN ILLINOIS EARLY
THIS MORNING WITH A WEAK AREA OF SHOWERS AND LOW CEILINGS ALONG THE
PREFRONTAL TROUGH. THE 13 KM RAP HAD STRONG CONVERGENCE ALONG THIS
FEATURE EARLY THIS MORNING AND SHOWS THE CONVERGENCE WEAKENING
THROUGH 12 UTC AS BOUNDARY SHIFTS EASTWARD. THE THREAT OF SHOWERS
FROM THIS FEATURE SHOULD QUICKLY DIMINISH BY 12 UTC. THE COLD FRONT
WILL EXIT INTO CENTRAL ILLINOIS BY 15 UTC WITH STRONG COLD ADVECTION
USHERING IN MUCH COOLER AIR THAN WE HAVE EXPERIENCED OVER THE PAST
48 HOURS AND CLOSER TO NORMAL HIGH TEMPERATURES FOR MID SEPTEMBER.

CLOUDS WILL CLEAR QUICKLY THROUGH THE DAY ON FRIDAY AS DRIER AIR
MOVES INTO THE REGION. HOWEVER THERE IS SOME CONCERN THAT THE
STRATUS LAYER CURRENTLY OVER THE EASTERN DAKOTAS WILL MOVE
SOUTHEASTWARD AND INTO THE REGION FRIDAY NIGHT INTO SATURDAY
MORNING. MODELS CONTINUE TO SUGGEST THAT THE CLOUDS WILL DISSIPATE
SO WILL LEAVE THE FORECAST CLEAR OVERNIGHT. THIS PLAYS DIRECTLY INTO
THE TEMPERATURE FORECAST FOR SATURDAY MORNING AND HAVE NOT MADE ANY
CHANGES TO THE PREVIOUS FORECAST FOR LOW TEMPERATURES IN THE MID TO
UPPER 40S. IF STRATUS DOES MOVE INTO THE REGION LOW TEMPERATURES ON
SATURDAY MORNING MAY BE WARMER THAN CURRENTLY FORECAST.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 327 AM CDT FRI SEP 20 2013

NEARLY IDEAL OUTDOOR FALL WEATHER WILL GRACE THE EXTENDED FORECAST
EACH DAY. SURFACE HIGH PRESSURE OVER THE GREAT LAKES WILL DOMINATE
THE WEATHER THROUGH THE NEXT 4 DAYS...WITH A DRY FROPA
TUESDAY...FOLLOWED BY ANOTHER PLEASANT HIGH PRESSURE SYSTEM. THOSE
WITH HOPE FOR MORE RAIN WILL HAVE TO WAIT ON A SINGLE COLD FROPA
EVENT WHICH IS FORECAST BY THE GFS AND ECMWF TO OCCUR AROUND FRIDAY
NIGHT BEYOND OUR CURRENT DAY 7.  THE TUESDAY TROF PASSAGE...SHOULD
BE MOISTURE STARVED...AND MAY ONLY BRIEFLY INCREASE HIGH LEVEL CLOUD
COVER.

LARGE DIURNAL SPREADS ARE FORECAST UNDER THE HIGH PRESSURE FOR
SATURDAY THROUGH MONDAY...WITH HIGHS IN THE MID 60S TO LOWER 70S AND
LOWS QUITE COOL...IN THE LOWER TO UPPER 40S IN GENERAL. THIS
TEMPERATURE RANGE REPRESENTS READINGS A FEW DEGREES BELOW CLIMATE
NORMALS...AND IS ONLY SIGNIFICANT IN COMPARISON TO OUR RECENT RECORD
WARMTH AND HUMIDITY. BEYOND MONDAY...MODEL BLENDS CONTINUE TO
INDICATE MODERATION...HOWEVER...I AM UNCERTAIN THAT THIS IS ACTUALLY
GOING TO OCCUR GIVEN OUR POTENTIAL FOR HAVING SOUTHEAST SURFACE FLOW
UNDER THE BUILDING UPPER RIDGE OF HIGH PRESSURE. THIS TRAJECTORY
COULD KEEP THE WIDE DIURNAL TEMPERATURE RANGES GOING...ALONG WITH
TEMPERATURES CLOSE TO NORMAL. WILL PASS THIS CONCERN ON THE THE NEXT
SHIFT WHICH SHOULD BE ABLE TO MORE FORMALLY PLACE THIS INTO THE
FORECAST BLEND.
ERVIN

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1250 PM CDT FRI SEP 20 2013

MVFR CIGS OF 2-3KFT AGL WILL OVERSPREAD AREAS ALONG AND NORTH OF
I-80 THROUGH 00Z/21. HIGH PRESSURE BUILDING INTO THE MIDWEST WILL
RESULT IN CLEARING SKIES FROM WEST TO EAST ACROSS EASTERN IOWA AND
NORTHERN ILLINOIS AFT 03Z/21. VFR CONDITIONS ARE EXPECTED DURING
THE DAY SATURDAY.                        ..08..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...08
SYNOPSIS...DC
SHORT TERM...DC
LONG TERM...ERVIN
AVIATION...08






AREA FORECAST DISCUSSION

NWS GOODLAND KS

 1127 AM MDT FRI SEP 20 2013

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 323 AM MDT FRI SEP 20 2013

INITIAL FORECAST CONCERN WILL BE TEMPERATURES THROUGH THE WEEKEND
...WINDS THROUGH THE WEEKEND...ESPECIALLY ON SUNDAY...WITH THE LAST
PROBLEM THE NEXT CHANCE FOR PRECIPITATION AT THE BEGINNING OF NEXT
WEEK. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH
AMERICA. OVER THE LAST 24 HOURS THE FLOW FROM THE CENTRAL PACIFIC
INTO NORTH AMERICA HAS AMPLIFIED. AT LOW LEVELS TWO DIFFERENT COLD
FRONTS HAVE BROUGHT IN A DRIER AND COOLER AIR MASS INTO THE AREA.

AT JET LEVEL...THE SREF FOLLOWED BY THE GFS WAS DOING THE BEST. AT
MID LEVELS...THE NAM WAS DOING A LITTLE BETTER THAN THE GFS...UKMET
AND CANADIAN. THE RUC FOLLOWED BY THE SREF AND THE NAM/ECMWF WAS
DOING THE BEST ON THE SURFACE WIND AND PRESSURE FIELD. THE GFS
FOLLOWED BY THE UKMET THEN SREF/NAM DID THE BEST ON THE LOW LEVEL
THERMAL FIELD.

TODAY/TONIGHT...WEAK SHOWERS AND THUNDERSTORMS HAVE POPPED NEAR THE
SOUTHERN AND WESTERN END OF THE FORECAST AREA. MODELS DO SHOW A RIGHT
REAR QUADRANT OF THE JET HANGING AROUND THROUGH THE MORNING AND IT
WILL BE ON TOP OF A WEAK MID LEVEL BAROCLINIC ZONE NEAR 700 MB.
WEAK FRONTOGENESIS IS IN THIS LAYER AS WELL WITH FAVORABLE THETA-E
LAPSE RATES. BASED ON LATEST TRENDS/MODEL DATA...WILL INCLUDE A
MENTION OF SPRINKLES...MOSTLY IN THE SOUTHERN HALF THROUGH MID
MORNING.

IN THE NORTHERN TIER OF COUNTIES...LACK OF CLOUD COVER HAS
ALLOWED TEMPERATURE/DEW POINT SPREADS TO BE VERY SMALL. HAVE ALREADY
SEEN PATCHY FOG IN SOME LOCATIONS. WHERE PRECIPITATION AND CLOUD
COVER ARE NOT EXPECTED...WILL PUT IN A MENTION OF PATCHY FOG ALSO
THROUGH MID MORNING. AT THIS TIME IT LOOKS LIKE CLOUD COVER WILL
DECREASE BY LATE MORNING. BASED ON TEMPERATURE BIASES AND CHANGE
OVER THE LAST 24 HOURS COMBINED WITH WHAT HAS BEEN DOING BEST ON
MAXES...MADE SOME ADJUSTMENTS UP FROM THE PREVIOUS FORECAST FOR THE
HIGH TEMPERATURES. MINS WILL BE WARMER TONIGHT DUE TO STRONGER
WINDS.

SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING TO
THE EAST WITH STRONG CROSS MOUNTAIN FLOW DEVELOPING. DURING THE LAST
HALF OF THE NIGHT THE MODELS SHOW THAT A LEFT FRONT QUADRANT
APPROACHES FROM THE SOUTH. THIS COULD SPREAD SOME HIGHER LEVEL CLOUDS
INTO THE AREA...ESPECIALLY IN THE SOUTHERN HALF. DUE TO A DRY AND
WELL MIXED AIR MASS...WILL KEEP THIS PERIOD DRY.

AS THE RESULT OF THE STRONG CROSS MOUNTAIN AND INCOMING UPPER
TROUGH MOVING INTO THE GREAT BASIN...LEE TROUGH WILL BEGIN TO
STRENGTHEN. INCREASING GRADIENT AND EXPECTED 3 HOUR PRESSURE FALLS
WOULD SUPPORT BREEZY SOUTHERLY WINDS DEVELOPING ACROSS THE AREA
DURING THE DAY. THERE WILL BE PLENTY OF SUN TO ALLOW HEATING AS 850
MB TEMPERATURES INCREASE 3 TO 5 DEGREES C FROM THE PREVIOUS DAY. SO
BASED ON THAT...RECENT BIASES...AND BETTER PERFORMING GUIDANCE...
RAISED THE MAXES ACCORDINGLY. LOW TEMPERATURES COULD STAY RATHER
MILD AS ATMOSPHERE STAYS WELL MIXED DUE TO STRENGTHENING LEE TROUGH.

SUNDAY/SUNDAY NIGHT...MODELS THEN START DIVERGING IN HOW THEY HANDLE
INCOMING UPPER TROUGH IN REGARDS TO SPEED AND AMPLITUDE. THIS
AFFECTS NUMEROUS PARAMETERS/FIELDS OF THE FORECAST. CURRENTLY THE
PATTERN OUT IN THE PACIFIC IS RATHER AMPLIFIED WITH A STRONG JET
STILL COMING DOWN THE WEST SIDE OF THE INCOMING UPPER TROUGH. THAT
WOULD SUPPORT HAVING A SLOWER AND MORE AMPLIFIED INCOMING UPPER
TROUGH. THIS PRETTY MUCH DISCOUNTS THE NAM AND THE SREF ARE VERY
FAST. MOST OF THE REMAINING OUTPUT IS CLOSE TO EACH OTHER ON THE
POSITION OF THE UPPER TROUGH AND RESULTING SURFACE PATTERN. GEFS
OUTPUT IS ALSO VERY SUPPORTIVE OF THE SLOWER SOLUTIONS WHICH ARE
THE GFS...ECMWF...UKMET AND CANADIAN.

SO WILL BASE FORECAST ON THOSE BUT CONFIDENCE IS A LITTLE BELOW
AVERAGE. MAIN SURFACE CONVERGENCE LIES NEAR THE WESTERN PORTION OF
THE FORECAST AREA ALONG WITH ACCOMPANYING MID/UPPER LIFT. CAP IS
ALSO THE WEAKEST THERE AS WELL. ALL THIS PLUS THE DETERMINISTIC QPF
AND GEFS PROBABILITY OF .05 SUPPORTS PULLING THE CHANCE OF
THUNDERSTORMS FURTHER WEST IN THE AFTERNOON. SO ADJUSTED THAT
ACCORDINGLY. AS STATED IN THE PREVIOUS FORECAST...MOISTURE COULD BE
THE LIMITING FACTOR ON COVERAGE AND SEVERITY. HOWEVER...LAPSE RATES
ARE VERY GOOD WITH VERY STRONG MID/UPPER LEVEL INDICATED...MAINLY
DURING THE EVENING. VERY STRONG PV ANOMALY ASSOCIATED WITH THIS
SYSTEM. PREVIOUS FORECAST HAS HIGH CHANCE IN THERE AND CONSIDERING
THE UNCERTAINTY BUT THE STRENGTH OF THE SYSTEM...FELT IT WAS
REASONABLE TO KEEP THOSE POPS.

VERY STRONG SYSTEM APPROACHING WILL CAUSE THE LEE TROUGH TO
STRENGTHEN EVEN MORE. PRESSURE GRADIENT AND 3 HOUR PRESSURE FALLS
DEFINITELY SUPPORT WINDY/NEAR WIND ADVISORY CONDITIONS. SO INCREASED
WIND SPEEDS TO NEAR WIND ADVISORY. 850 MB TEMPERATURES SUPPORT
HAVING HIGH TEMPERATURES NEAR WHAT THE EXPECTED SATURDAY MAXES ARE.
SO ADJUSTED ACCORDINGLY.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 301 AM MDT FRI SEP 20 2013

EARLY MONDAY...ECMWF AND GFS PLACE THE UPPER LEVEL SHORTWAVE TROUGH
AXIS OVER NORTHEAST COLORADO WITH THE COLD FRONT BISECTING THE
FORECAST AREA. THE NAM IS THE MUCH FASTER OUTLIER AND PER WPC
MODEL DIAGNOSTICS DISCUSSION A BLEND OF THE GFS AND ECMWF IS
FAVORED FOR POSITION/TIMING. SHOWERS AND THUNDERSTORMS SHOULD BE
LIMITED TO THE EASTERN HALF OF THE FORECAST AREA MONDAY
MORNING...POSSIBLY THROUGH EARLY AFTERNOON DEPENDING ON TIMING.

AS THE SHORTWAVE TROUGH MOVES QUICKLY NORTHEAST...STRONG WESTERLY
MID/UPPER FLOW DEVELOPS OVER THE NORTHERN ROCKIES AND NORTHERN
PLAINS BY TUESDAY AND LEE SIDE TROUGH STRENGTHENS IN RESPONSE. VERY
SUBTLE UPPER LEVEL RIDGING MAY BE PRESENT ON TUESDAY BUT NOT ENOUGH
FOR TEMPERATURES TO SIGNIFICANTLY EXCEED NORMAL VALUES. A
SIGNIFICANT UPPER TROUGH WILL DEVELOP OVER THE WESTERN CONUS BY
WEDNESDAY. MODELS DISAGREE ON THE TIMING AND POSITION OF THIS
TROUGH...ALBEIT TO A LESSER EXTENT THAN PREVIOUS RUNS. GFS IS THE
QUICKEST AT EJECTING IT NORTHEASTWARD. EVEN SO...GFS ENSEMBLE MEAN
QPF REMAINS NORTH AND NORTHWEST OF THE FORECAST AREA THROUGH THE END
OF THE EXTENDED PERIOD...SO THE FORECAST REMAINS DRY BEYOND MONDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1121 AM MDT FRI SEP 20 2013

VFR CONDITIONS FORECAST FOR THE 18Z TAFS. LIGHT SOUTHERLY WINDS
WILL CONTINUE THROUGH THE PERIOD. POINT SOUNDING FOR KGLD SHOWS
A POSSIBILITY OF LOW CLOUDS/FOG...BUT AM NOT CONFIDENT ENOUGH AT
THIS TIME TO PLACE A MENTION OF IT IN THE TAF GIVEN HOW BRIEF THE
LOW LEVELS SATURATE.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...BULLER
LONG TERM...BRB
AVIATION...JTL







AREA FORECAST DISCUSSION

NWS PADUCAH KY

 240 PM CDT Fri Sep 20 2013

.SHORT TERM /Tonight through Sunday night/...
ISSUED AT 240 PM CDT FRI SEP 20 2013

Forecast seems to be panning out fairly well. Widespread rain has
overspread most of the forecast area this afternoon. Aside from a
convective cluster over western Kentucky...deep convection has been
largely absent. Instability has been limited by lack of solar
heating due to thickening mid/high clouds.

The qpf forecast seems to be on track...with the lowest amounts in
southern IL and southeast MO. Heavy rainfall is still occurring and
expected in western KY and possibly southwest IN. Due to dry
ground...any issues should be limited to urban and poor drainage
areas. Rainfall rates will continue to be locally over one inch per
hour in convection.

The latest HRRR is fairly close to the model consensus. The back
edge of the rain will move across the kpah/kevv areas in the 03z to
06z time frame. The precip will end in the khop area by 12z.

Clearing will occur on Saturday morning...with nothing more than
some scattered cu in the afternoon. 850 mb temps are forecast to
fall to around 10...which supports mos guidance highs in the mid
70s.

Little change in 850 mb temps or moisture profiles is forecast
through Sunday night. This will keep clear and cool conditions in
place...with daytime highs in the 70s and overnight lows in the mid
40s to near 50. North to northeast low level winds will slowly
decrease as high pressure builds overhead.


.LONG TERM /Monday through Friday/...
ISSUED AT 240 PM CDT FRI SEP 20 2013

As we head into next week, it now appears as though the upper level
high over the  eastern U.S. will shift farther east as short wave
energy moves east into the MS River Valley. It still appears as
though our region may stay in between the two main branches of
energy, one passing to our north and the other just to our
south/east. If current trends continue, later forecasts may need to
mention a chc of rain in srn portions of west KY on Tuesday/Tue
night.

Thereafter...the upper high over the southeast U.S. will begin to
flex its muscle, and build north into the Ohio Valley. Thus... we
should see less cloud cover and warming temps as we head into the
Wed/Thu/Fri time frame. Most locations will likely be back into the
middle 80s by Wednesday afternoon. Humidity levels should stay
fairly comfortable until late in the week, when southerly flow will
develop ahead of an approaching cold front.

&&

.AVIATION...
ISSUED AT 1237 PM CDT FRI SEP 20 2013

Cold front pushing into the region 22z-02z, turning winds from
west to north around 10 kts after the passage. Expect numerous
showers and MVFR vsbys/cigs ahead of the front. Cannot rule out
isolated thunder along and south of the OH River until the front
passes. May also be a period of IFR/Low IFR behind the front in
light rain or DZ. Skies should finally clear 08-12z.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

SHORT TERM...MY
LONG TERM...GM
AVIATION...GM











AREA FORECAST DISCUSSION...UPDATED AVIATION

NWS ST LOUIS MO

 1257 PM CDT Fri Sep 20 2013

.UPDATE:
Issued at 1040 AM CDT Fri Sep 20 2013

15z surface obs show cold front knocking on the door of STL metro,
just to the NW, and is expected to move thru during the midday
hours. Low clouds expected to linger for a couple hours after
FROPA, with a thick CS cloud deck hanging around for thru the rest
of the afternoon over many areas. This thick cloud cover will
result in limited sunshine and combined with somewhat decent lo
level CAA, will result in very limited temp recoveries behind the
front today with most locales seeing near steady temps.

Substantial clearing will take place early this evening with
expected departure of thick high clouds and associated temp and
wind dropoff will occur as well.

Rain will experience one final surge slightly back to the NW as it
rides up I-44 in MO during the midday and early afternoon hours
before it then accelerates off and out of the area later in the
afternoon. Some patchy drizzle has also been reported near and
just behind the cold front and have added that in as well,
sharpening up the gradient between areas that should receive
measurable rainfall from those that do not but may still see some
precipitation. Removed thunder from forecast with instability very
limited from here on out.

TES

&&

.SHORT TERM:  (Through Tonight)
Issued at 326 AM CDT Fri Sep 20 2013

Main concern will be how quickly the rain will exit the area today.
Cold front currently extends from Kirksville to Sedalia to Nevada.
Ahead of it, there is a large band of rain with the leading edge
of the thunderstorms extending from just northeast of metro St.
Louis southwestward West Plains. This line should continue to
move east in the near term...though there will continue to be some
weakening in this line as the RAP shows the 925-850mb moisture
convergence diminishing. The cold front will continue to move
southeast today, clearing the CWA by 21Z. The main band of rain
with embedded thunderstorms will be found ahead of it, aided by
ascent from the front and the deep upper through moving across the
central CONUS. This is generally follows the latest runs of the
HRRR which shows rain slowly spreading southeast with time.

With clouds and rain today, temperatures will be much cooler than
yesterday. Some locations in south and east may not see much
diurnal recovery.

Britt

.LONG TERM: (Saturday through Wednesday)
Issued at 326 AM CDT Fri Sep 20 2013

Forecast remains dry in the long term.  Strong subsidence sets in
the wake of the upper trough as upper ridge builds in over the
region by late Sunday. Deep trough that enters the West Coast over
the weekend still shears out before it can give us any rain. Then
GFS/ECMWF both begin to amplify pattern over the CONUS by the
middle of next week with a trough over the Rockies and ridge over
the Mississippi Valley on Wednesday.

A dry airmass and light winds/mainly clear skies should allow for
some excellent radiational cooling at night. Went a few degrees
below guidance for lows over the weekend into early next week.

Britt

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1257 PM CDT Fri Sep 20 2013

Cold front at 17z was moving thru the NW half of STL metro and is
expected to make its way thru the TAF sets there between now and
20z. IFR CIGs and MVFR VSBYs in drizzle are expected in the
frontal zone from time to time. Improving conditions to VFR will
then occur late this afternoon in this area with VFR for the
remainder of the valid period. KUIN and KCOU will remain VFR thru
the valid period. Otherwise, NW-N surface winds can be anticipated
for the valid period for those areas behind the front.

Specifics for KSTL: Cold front at 17z had moved thru KSET and was
almost to the terminal where a wind shift out of the NW will
occur. IFR CIGs and MVFR VSBYs in drizzle can also be expected in
the frontal zone from time to time until around 20z, although
delays and slowdowns seem to be the theme of the fronts movement
as of late. Rapidly improving conditions to VFR will then occur
late this afternoon with VFR for the remainder of the valid
period. Fog is not forecast due to rapid drying also expected to
occur tonight. Otherwise, NW-N surface winds can be anticipated
for the valid period.

TES

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





AREA FORECAST DISCUSSION

NWS NEWPORT/MOREHEAD CITY NC

 649 PM EDT FRI SEP 20 2013

.SYNOPSIS...
HIGH PRESSURE OVER THE AREA WILL GIVER WAY TO LOW PRESSURE TONIGHT
AND SATURDAY WITH SURFACE FRONT EXPECTED TO CROSS THE AREA SATURDAY
NIGHT. HIGH PRESSURE WILL BUILD OVER THE AREA FOR THE FIRST PART OF
THE WEEK. A SYSTEM WILL APPROACH FROM THE SOUTH WEDNESDAY AND MOVE
EAST OF THE THE AREA THURSDAY WITH HIGH PRESSURE BUILDING BACK IN
BY THE END OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 645 PM FRIDAY...PATCHY SHOWERS HAVE IMPACTED THE FAR INLAND
COUNTIES TODAY BUT HAVE GREATLY DECREASED IN COVERAGE OVER THE
PAST COUPLE OF HOURS. MOST OF THE HIGH RESOLUTION WRF MODELS ALONG
WITH THE NAM12 AND RAP INDICATE A LEAST SOME PATCHY SHOWERS
CONTINUING INTO THE OVERNIGHT HOURS...WITH COVERAGE INCREASING
AFTER MIDNIGHT AS FRONT APPROACHES FROM THE WEST. WILL KEEP SLIGHT
CHC POPS OVER THE FAR INLAND TIER OF COUNTIES THROUGH ABOUT
06Z...THE SPREAD TO THE HIGHWAY 17 CORRIDOR AFTER 06Z. NO REAL
CHANGES IN FORECAST TEMPERATURES OVERNIGHT AS TEMPS WILL MUCH
MILDER THAN RECENT NIGHTS AS THE LOW-LEVELS MOISTEN AND THE FLOW
BECOMES SE/S.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
AS OF 124 PM FRI...HIGH PRESSURE ALOFT WILL WEAKEN THROUGH THE DAY
ON SATURDAY AS FULL LATITUDE TROUGH APPROACHES FROM THE WEST. UPPER
LOW OFF THE COAST WILL BE ABSORBED BY THE APPROACHING SYSTEM.
SURFACE REFLECTION FRONT WILL APPROACH THE AREA DURING THE
DAY...WITH SURFACE FLOW BECOMING SOUTHWESTERLY AND PICKING UP IN
SPEED TO 10 TO 15 MPH. AS FRONT APPROACHES WITH WEAK UPPER LEVEL
FORCING...WILL HAVE SMALL BUT INCREASED POPS. HIGHEST CHANCES WILL
BE IN WESTERN SECTIONS DURING THE LATER AFTERNOON...BUT WILL KEEP
POPS AROUND 30 IN THOSE AREAS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
SHORT WAVE EMBEDDED IN THE DIGGING FULL LATITUDE TROF DEVELOPING
OVER THE EASTERN STATES WILL PASS THRU THE FORECAST AREA SAT
NIGHT. GIVEN THE GOOD MID LEVEL MOISTURE INFLOW FROM THE GULF
REGION AND SFC MOIST FLOW OFF THE ATLANTIC HAVE UPPED POPS TO
LIKELY SAT NIGHT. INSTABILITY WILL BE LIMITED DUE TO THE
UNFAVORABLE DIURNAL CYCLE BUT WILL HANG ONTO ISOLD TSTM MENTION
GIVEN THE MODEST SHEAR, MAINLY FOR SAT EVE AREAWIDE THEN SHIFTING
TO THE COAST AFTER MIDNIGHT. SHORTER RANGE MODELS ARE IN DECENT
AGREEMENT PUSHING THE SFC COLD FRONT THRU THE AREA OVERNIGHT AND
OFFSHORE BY DAYBREAK SUNDAY. RAINFALL TOTALS DO NOT LOOK TO BE
IMPRESSIVE GIVEN THE RELATIVELY FAST MOVING SYSTEM WITH GENERAL
ONE HALF INCH AMOUNTS EXPECTED AND LOCALLY HIGHER AMOUNTS.

SFC BNDRY SAGS SOUTH OF THE REGION ON SUNDAY. CUD BE SOME
LEFTOVER PRECIP ESP OVER SOUTHERN AREAS BUT MOST OF SUNDAY INTO
SUNDAY NIGHT SHUD BE DRY WITH GRADUALLY CLEARING AS HIGH PRESSURE
RIDGES IN FROM THE NW. BROAD EAST COAST TROF WILL PUSH OFFSHORE
EARLY NEXT WEEK AS SHORT WAVE RIDGE SLIDES EAST TO THE NORTHERN
MID ATLC STATES. SOUTHERN STREAM SYSTEM UNDERCUTS THE RIDGE OVER
THE GULF COAST AND SE STATES WHICH WILL THROW CLOUDS AND LOW
PRECIP CHANCES AS FAR NORTH AS EASTERN NC DURING MIDWEEK.

UPPER RIDGE BUILDS OVER SE STATES IN THE WAKE OF THE SOUTHERN
STREAM SYSTEM MOVING OFF THE COAST LATE IN THE WEEK...WITH A
RETURN TO MAINLY CLEAR SKIES...COOL NIGHTS AND MILD DAYS.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM /TONIGHT AND SATURDAY/...
AS OF 645 PM FRI...GIVEN SKIES THAT HAVE REMAINED RELATIVELY
CLEAR AT THE TAF SITES...AND WITH LOW-LEVEL FLOW BECOMING MORE
SE/S TOWARD MORNING...AM A BIT MORE CONCERNED ABOUT THE
DEVELOPMENT OF FOG AND STRATUS TOWARD MORNING AS ALL OF THE
NUMERICAL MOS GUIDANCE INDICATES LOW CEILINGS AND VSBYS AFTER 08Z
OR SO. WILL BE A BIT MORE CONSERVATIVE...BUT WILL INDICATE A
PERIOD OF MVFR VSBYS/CEILINGS TOWARD MORNING. GENERALLY VFR FOR
MOST OF SATURDAY AS PRECIPITATION SHOULD NOT BECOME MORE
WIDESPREAD UNTIL LATER IN THE DAY.

LONG TERM /SAT NIGHT THROUGH WEDNESDAY/...
SHOWERS/ISOLD TSTMS AHEAD OF A COLD FRONT SAT NIGHT WILL LIKELY
BRING PERIODS OF SUB-VFR CONDITIONS. GRADUAL IMPROVEMENT IN FLYING
CONDITIONS ON SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTH
THROUGH EARLY NEXT WEEK. FRINGE EFFECTS OF A SOUTHERN STREAM
SYSTEM MOVING OFF THE SE COAST WILL BRING CLOUDINESS AND PRECIP
CHANCES BACK INTO THE AREA TUE NIGHT AND WEDNESDAY WITH SUB-VFR
CONDITIONS POSSIBLE.

&&

.MARINE...
SHORT TERM /TONIGHT AND SATURDAY/... AS OF 650 PM FRI...NE/ENE WINDS
SHOULD GRADUALLY VEER TO A MORE SE/S DIRECTION TOWARD MORNING AS
AXIS OF HIGH PRESSURE RIDGE MOVES OFFSHORE AS A COLD FRONT
APPROACHES. WIND SPEEDS SHOULD BE 15 KNOT OR LESS WITH SEAS
GENERALLY 2 TO 4 FEET WITH LONG PERIOD 10 TO 11 SECOND SWELLS. AS
THE FRONT APPROACHES THE AREA SATURDAY...BRINGING WIND TO A
SOUTHERLY DIRECTION...AND INCREASING SPEEDS TO 10 TO 15 KNOTS AS
GRADIENT INCREASING AHEAD OF THE APPROACHING FRONT. SEAS WILL
REMAIN 2 TO 4 FEET THROUGH THE PERIOD.

LONG TERM /SAT NIGHT THROUGH WEDS/...
MODERATE SW FLOW AHEAD OF A COLD FRONT PASSAGE SAT NIGHT WILL
SHIFT WEST THEN NW AND DECREASING SLIGHTLY ON SUNDAY. THE MAIN
PUSH OF COLD AIR ADVECTION WILL MOVE DOWN THE NC COAST LATE SUNDAY
NIGHT/EARLY MONDAY WITH N/NE WINDS (AND SEAS) APPROACHING SMALL
CRAFT ADVISORY LEVELS. LIGHT TO MODERATE NE WINDS WILL CONTINUE
THRU THE EARLY PART OF THE WEEK THEN INCREASE SOMEWHAT AS LOW
PRESSURE PASSES OFF THE SE COAST DURING MIDWEEK.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...CGG
NEAR TERM...CTC
SHORT TERM...CGG
LONG TERM...BTC
AVIATION...CTC/BTC/BM
MARINE...CTC/BTC/CGG







AREA FORECAST DISCUSSION

NWS PORTLAND OR

 902 AM PDT FRI SEP 20 2013

.SYNOPSIS... A PACIFIC FRONT WILL BRING DETERIORATING CONDITIONS TO
THE AREA TODAY. RAIN WILL SPREAD INTO THE COAST BY MIDDAY AND ACROSS
THE WILLAMETTE VALLEY BY THE MID TO LATE AFTERNOON HOURS. ADDITIONAL
RAIN SHOWERS WILL CONTINUE FRIDAY NIGHT INTO SATURDAY WITH PERHAPS A
FEW LIGHTNING STRIKES. A STRONGER FRONT WILL BRING WINDY CONDITIONS
TO THE COAST...BREEZY CONDITIONS INLAND...AND ANOTHER ROUND OF
WIDESPREAD RAIN TO THE AREA SUNDAY. COOL AND UNSETTLED WEATHER SHOULD
CONTINUE FOR THE FIRST HALF OF NEXT WEEK WITH PERIODS OF SHOWERS
BEFORE SOME DRYING FOR THE LATTER HALF OF NEXT WEEK.

&&

.UPDATE...SEVERAL WAVES ALONG THE FRONT OFFSHORE WHICH WILL SLOW THE
PROGRESS OF THE FRONT IN THE NORTH...WHILE ANOTHER WAVE IS NOTED
FURTHER SOUTH. HAVE SEEN LIGHTNING OFFSHORE FROM BROOKINGS IN
SOUTHERN OREGON WITH THIS SECONDARY WAVE...WHICH IS WHERE THE LATEST
HRRR SUGGESTS CONVECTIVE ACTIVITY WILL CONTINUE INLAND. MODELS ARE
SHOWING WEAK INSTABILITY ALONG THE ENTIRE FRONT EVEN UP NEAR
PORTLAND WITH HINTS OF CONVECTIVE ELEMENTS IN THE HRRR...SO CANNOT
RULE OUT AN ISOLATED STRIKE ANYWHERE FOR A BRIEF TIME RIGHT WITH THE
FRONTAL PASSAGE IN THE LATE AFTERNOON AND EARLY EVENING.  /KMD

.SHORT TERM...INFRARED SATELLITE IMAGERY SHOWS WAVES OF SHOWERS
ROLLING NORTHWARD ALONG A FRONTAL BOUNDARY APPROXIMATELY 100-150
MILES OFF THE PACIFIC NORTHWEST COAST THIS MORNING. SUFFICIENTLY DEEP
INSTABILITY IN THE VICINITY OF THE FRONT HAS RESULTED IN A FEW
LIGHTNING STRIKES TOWARDS VANCOUVER ISLAND OVERNIGHT. KLGX DOPPLER
RADAR INDICATES A FEW LIGHT SHOWERS AHEAD OF THE MAIN FRONTAL BAND
MAY BRING LIGHT SPOTTY SHOWERS TO THE COAST THIS MORNING. HRRR AND A
LINEAR EXTRAPOLATION OF THE RADAR INDICATES THE STEADIER AND HEAVIER
RAIN WILL LIKELY HIT THE COAST DURING THE LATE MORNING HOURS AND
SPREAD INTO THE WILLAMETTE VALLEY DURING THE MID TO LATE AFTERNOON
HOURS. THERE IS SOME CONCERN THAT WE COULD SEE CONVECTION WITH THE
FRONT AS IT PUSHES INLAND LATE THIS AFTERNOON AND EARLY
EVENING...BUT FOR NOW KEPT THE THUNDER MENTION PRIMARILY LIMITED TO
THE COAST AND CENTRAL OREGON CASCADES.

A COLD UNSTABLE AIRMASS WILL SLOWLY WORK ITS WAY OVER THE AREA
TONIGHT INTO SATURDAY. THIS SHOULD RESULT IN PERIODS OF SUN BREAKS
BETWEEN SHOWERS SATURDAY WITH A FEW RUMBLES OF THUNDER POSSIBLE JUST
ABOUT ANYWHERE. SNOW LEVELS WILL LOWER TO NEAR 6-6.5KFT SATURDAY.

BRIEF SHORTWAVE RIDGING SATURDAY NIGHT SHOULD RESULT IN SHOWERS
DECREASING ACROSS THE AREA. HOWEVER...THE RESPITE WILL BE SHORT
LIVED AS THE NEXT STORM SYSTEM SPREADS WIDESPREAD RAIN FROM
NORTHWEST TO SOUTHEAST ACROSS THE AREA SUNDAY. IN ADDITION...A
STRONG FRONT WILL BRING WINDY CONDITIONS TO THE COAST AND BREEZY
CONDITIONS INLAND ON SUNDAY. THE NAM IS THE STRONGEST SOLUTION AT
THIS POINT...WITH THE GFS BACKING OFF JUST A BIT ON 925MB AND 850MB
WINDS FROM PREVIOUS MODEL RUNS SO CONFIDENCE IS NOT PARTICULARLY
HIGH A HIGH WIND PRODUCT WILL BE NEEDED FOR THE COAST.
NONETHELESS...WIND GUSTS OF AT LEAST 45 TO 55 MPH APPEAR TO BE A
SAFE BET FOR MANY LOCATIONS ALONG THE COAST.

ONSHORE FLOW WITH COOLING TEMPERATURES ALOFT SHOULD RESULT IN
ADDITIONAL ROUNDS OF SHOWERS MONDAY AND TUESDAY AS AN UPPER LEVEL
TROUGH DROPS INTO THE PACIFIC NORTHWEST. /NEUMAN

.LONG TERM...SUNDAY EVENING THROUGH THURSDAY...
EXPECT THE MAIN FRONTAL BAND TO SHIFT INLAND SUNDAY EVENING. THE
UPPER LOW ASSOCIATED WITH THIS FRONT WILL BEGIN THE EXTENDED PERIOD
OFF THE COAST OF CENTRAL B.C. THEN DIG SOUTH AND EAST AND WILL BE ON
TOP OF THE AREA TUESDAY NIGHT. WITH THE LOW TO THE NORTH WE WILL
MAINTAIN A GOOD BATCH OF ONSHORE FLOW THROUGH AT LEAST TUESDAY.
SEVERAL WAVES OF ENERGY WILL MIGRATE THROUGH THE AREA FOR PERIODS OF
SHOWERS...THOUGH EXPECT LITTLE IN THE WAY OF BREAKS IN ELEVATED
TERRAIN...AND NO OBVIOUS DRY PERIODS FOR THE LOWLANDS AS WELL.
TEMPERATURES WILL REMAIN BELOW NORMAL AND GENERALLY IN THE 60S FOR
THE LOWLANDS.

THE UPPER LOW WILL SHIFT SOUTH AND EAST OF THE AREA THROUGH THE DAY
ON WEDNESDAY. AN UPPER LEVEL RIDGE WILL BE OFFSHORE ON WEDNESDAY
EVENING AND ATTEMPT TO SLOWLY PUSH ONSHORE. THE FLOW TURNS NORTH TO
NORTHEASTERLY WHICH WILL ALLOW THE AREA TO DRY OUT THROUGH AT LEAST
FRIDAY WHILE ANOTHER FRONT ATTEMPTS TO SQUASH THE RIDGE OFFSHORE. A
RETROGRADING INLAND RIDGE MAY KEEP THIS AT BAY FOR NEXT WEEKEND.
EXPECT TEMPERATURES TO REBOUND TO AT LEAST THE LOWER 70S AND CLOSER
TO NORMAL WITH MORE IN THE WAY OF SUNSHINE AFTER MORNING FOG.
KMD/ROCKEY

&&

.AVIATION...MAINLY VFR CONDITIONS OVER THE REGION THIS MORNING.
CLOUDS WILL THICKEN AND LOWER THROUGHOUT THE DAY AS A FRONT
APPROACHES FROM THE WEST. AREAS OF MVFR CIGS ALONG THE COAST THIS
MORNING WILL EXPAND LATER TODAY. BUT INLAND VFR CONDITIONS ARE
LIKELY TO PERSIST INTO THE EVENING BEFORE AREAS OF MVFR CONDITIONS
DEVELOP AFTER 05Z.

KPDX AND APPROACHES...VFR EXPECTED THROUGH 05Z. CLOUDS WILL LOWER
THIS EVENING AS A FRONT MOVES IN...WITH A GOOD CHANCE FOR MVFR
CIGS AFTER 05Z.

&&

.MARINE...WIND FIELDS WITH THE FRONT MOVING IN THIS MORNING WERE
WEAKENING...AND AT THIS POINT IT APPEARS UNLIKELY TO SEE MORE THAN A
FEW GUSTS OVER THE SMALL CRAFT WIND CRITERIA. SEAS HOWEVER HAVE BEEN
PICKING UP QUICKLY EARLY THIS MORNING AS A WESTERLY SWELL ON THE
ORDER OF 10 TO 12 FT HAS MOVED IN. THE FRONT ITSELF...WITH SE
WINDS AHEAD OF IT AND SW WINDS BEHIND...IS EXPECTED TO REACH THE
COAST BETWEEN 11 AM AND 2 PM.

A STRONGER SYSTEM WILL REACH THE WATERS SUN...WITH WINDS LIKELY
TOPPING OUT IN THE GALE CATEGORY. WITH THE BIGGER WINDS COME THE
PROSPECTS FOR BIGGER SEAS...LIKELY TO BE ON THE ORDER OF 15 FT BY
MON.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 5 AM PDT
     SATURDAY.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...
    HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
    WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
    WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.







AREA FORECAST DISCUSSION...UPDATED

NWS ABERDEEN SD

 1224 PM CDT FRI SEP 20 2013

.UPDATE...
SEE THE UPDATED AVIATION DISCUSSION BELOW.

ADJUSTED CLOUD COVER THIS MORNING. LATEST SATELLITE IMAGERY SHOWS
A SWATH OF STRATUS OVER THE EASTERN CWA. STILL EXPECT THIS TO
CLEAR OUT BY EARLY AFTERNOON. LOWERED TEMPERATURES TONIGHT A FEW
DEGREES ACROSS THE JAMES RIVER VALLEY AND BORDERING COUNTIES SINCE
RETURN FLOW LOOKS LIKE IT WILL BE DELAYED. WILL LIKELY NEED A FROST
ADVISORY OVER PARTS OF THE AREA TONIGHT BUT WILL WAIT FOR 12Z
MODELS BEFORE DETERMINING EXACT AREA OF CONCERN.

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY
UPPER TROUGH AXIS IS CENTERED OVER THE DAKOTAS EARLY THIS MORNING
WITH A SMALLER INDIVIDUAL SHORTWAVE/VORT MAX SPINNING ACROSS
NORTHEAST SD. ISOLATED SPRINKLES/LIGHT SHOWERS HAVE BEEN OCCURRING
OVER THE PAST SEVERAL HOURS IN ASSOCIATION WITH THIS SMALLER VORT
MAX. HRRR PICKING UP ON THIS SOMEWHAT AND SHOWS THIS ACTIVITY
MOVING OUT OF THE AREA LATER THIS MORNING AS THE SHORTWAVE EXITS.
PLENTY OF STRATUS CLOUDS WITH THIS WAVE AS WELL. SOUNDINGS ACROSS
THE CWA SUGGEST MORE SUN THAN CLOUDS ACROSS THE WESTERN CWA
THROUGH THE DAY...BUT ACROSS THE EAST...STRATUS WILL TAKE SOME
TIME TO EXIT. AND WHATEVER STRATUS DOES EXIT OR DISSIPATE WILL
LIKELY BE FILLED BY CUMULUS DEVELOPMENT BY LATE MORNING OR EARLY
AFTERNOON. TEMPS WILL BE RATHER COOL ACROSS THE EASTERN CWA TODAY
WHERE TEMPS ALOFT ARE COLDEST. HIGHS IN THE 60S CAN BE EXPECTED
HERE.

SURFACE HIGH PRESSURE CENTERS ITSELF OVER THE REGION TONIGHT INTO
SATURDAY MORNING. THIS IS A COOL AIR MASS MOVING INTO THE AREA SO
WITH CLEARING SKIES AND LIGHT WINDS OVERNIGHT...LOOKING AT A
CHILLY START TO THE MORNING ON SATURDAY. MORNING LOWS IN THE 30S
ARE FORECAST FOR MOST OF THE EASTERN CWA...WITH THE JAMES VALLEY
LIKELY FALLING INTO THE MID 30S.

WARM AIR ADVECTION RAMPS BACK UP AGAIN SATURDAY INTO SUNDAY...WITH
WARMING TEMPERATURES AND INCREASING SOUTHEAST WINDS. BREEZY/WINDY
CONDITIONS LOOK LIKELY ON SUNDAY AS THE PRESSURE GRADIENT ACROSS
THE CWA BECOMES RATHER TIGHT.

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY

THE LONG TERM SHOULD BE FAIRLY ACTIVE ACCORDING TO THE LATEST
MODELS. A SOMEWHAT PROGRESSIVE MID LEVEL FLOW IS ANTICIPATED WITH
ONE DECENT S/W TROF MOVING THROUGH SUNDAY NIGHT AND MONDAY. THIS
SHOULD BRING RAIN/THUNDER TO MUCH OF THE CWA...ALTHOUGH MOST
MODELS ARE MORE BULLISH WITH AMOUNTS OVER THE WESTERN CWA VS THE
EAST. THEN A FAIRLY DEEP TROF DIGS INTO THE WESTERN CONUS SETTING
UP SOUTHWEST FLOW ALOFT FOR THE LATTER PART OF NEXT WEEK. A
FRONTAL BOUNDARY WILL BE PARKED ACROSS THE AREA. RAIN CHANCES ARE
EXPECTED MAINLY BEHIND THE FRONT THROUGH THE PERIOD. THE MODELS DO
HAVE SOME DIFFERENCES ON THE STRENGTH OF S/W ENERGY AND SFC WAVES
RIDING THE FRONT...BUT AT THAT TIME RANGE THIS IS EXPECTED. OVERALL
TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD.

&&

.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

STRATUS CONTINUES TO SLOWLY DRIFT EAST AND ERODE THIS AFTERNOON.
KATY IS THE ONLY REMAINING SITE WITH MVFR CIGS...BUT IS EXPECTED
TO CLEAR IN THE NEXT HOUR OR TWO. OTHERWISE...VFR CONDITIONS WILL
PREVAIL. A HIGH PRESSURE RIDGE WILL MOVE ACROSS THE REGION
TONIGHT...SO WEST TO NORTHWEST WINDS WILL GRADUALLY DISSIPATE
UNDERNEATH THE RIDGE...AND THEN WILL SWITCH TO THE SOUTHEAST
BEHIND THE RIDGE SATURDAY MORNING.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
UPDATE...WISE
SHORT TERM...TMT
LONG TERM...TDK
AVIATION...SERR

WEATHER.GOV/ABERDEEN






AREA FORECAST DISCUSSION

NWS MEMPHIS TN

 1244 PM CDT FRI SEP 20 2013

.UPDATE...AVIATION DISCUSSION.

&&

.PREV DISCUSSION... /ISSUED 1002 AM CDT FRI SEP 20 2013/

DISCUSSION...14Z SURFACE ANALYSIS PLACES A COLD FRONT FROM HUDSON
BAY BACK THROUGH EAST CENTRAL MISSOURI...ARKANSAS...WITH AN
EMBEDDED SURFACE LOW LOCATED OVER NORTHEAST TEXAS. TEMPERATURES AS
OF 9 AM CDT ARE IN THE 70S AT MOST LOCATIONS.

REGIONAL WSR-88D RADAR TRENDS INDICATE THE LEADING EDGE OF SHOWERS
AND THUNDERSTORMS ARE ALREADY ALONG AND WEST OF THE MISSISSIPPI
RIVER. SHORT TERM MODELS INCLUDING THE 3KM HRRR INDICATE A
POTENTIAL FOR RAIN ENDING EARLIER TONIGHT ALONG AND WEST OF THE
MISSISSIPPI RIVER. WILL MAKE ADJUSTMENTS TO AFTERNOON RAIN
CHANCES BASED ON CURRENT TRENDS AND CONSIDER TRIMMING CHANCES BACK
TONIGHT ACROSS THE ABOVE MENTIONED AREA AFTER THE 12Z GFS ARRIVES.

NOT ANTICIPATING ANY STRONG TO SEVERE THUNDERSTORM POTENTIAL AT
THIS TIME. HOWEVER...SUFFICIENT FORCING...PRECIPITABLE WATER VALUES
ABOVE 2 INCHES AND A SLOW MOVING FRONT STILL INDICATE A POTENTIAL
FOR HEAVY RAINFALL ACROSS THE MID SOUTH THROUGH TONIGHT. NOT
PLANNING ON ISSUING A FLASH FLOOD WATCH AT THIS TIME AS FLASH
FLOOD GUIDANCE VALUES STILL REMAIN HIGH DUE TO THE RECENT DRY
WEATHER AND ANTICIPATING AN AVERAGE OF RAINFALL UP TO 1-2 INCHES.

WILL MAKE ADJUSTMENTS TO ALL OTHER ELEMENTS AS NEEDED TO ACCOUNT
FOR SHORT TERM TRENDS.

UPDATED GRIDS WILL BE AVAILABLE SHORTLY.

CJC

PREV DISCUSSION... /ISSUED 624 AM CDT FRI SEP 20 2013/

UPDATE...
UPDATED FOR 12Z AVIATION DISCUSSION.

PREV DISCUSSION... /ISSUED 434 AM CDT FRI SEP 20 2013/

DISCUSSION...

CURRENTLY...A SIGNIFICANT MID LEVEL TROF IS PUSHING INTO THE UPPER
MS VALLEY WITH AN ASSOCD COLD FRONT STRETCHING FROM NEAR CHICAGO
SOUTHWEST INTO OKLAHOMA. ANOTHER PIECE OF UPPER LEVEL ENERGY IS
PUSHING FROM MEXICO INTO TEXAS WHICH IS HELPING TO FUNNEL DEEP
MOISTURE NORTHEASTWARD ALONG THE FRONT. RAIN WILL START PUSHING
INTO THE MIDSOUTH AT SUNRISE. TEMPS ARE VERY MILD ACROSS THE AREA
UNDER HIGH CLOUDS AND SOUTHERLY FLOW...IN THE UPPER 60S TO MID
70S.

TODAY THROUGH TONIGHT...THE MID LEVEL TROF ASSOCD WITH THE
NORTHERN BRANCH OF THE JET WILL PHASE WITH THE SOUTHERN STREAM
ENERGY COMING OUT OF TEXAS TO PRODUCE A HEAVY RAIN EVENT ACROSS
THE MIDSOUTH. DEEP MOISTURE WILL FLOW NORTHEASTWARD ALONG THE
SURFACE FRONT THAT WILL PUSH ACROSS THE AREA TODAY AND TONIGHT.
MODELS HAVE PRECIP WATER VALUES CLIMBING ABOVE 2 INCHES ALONG AND
AHEAD OF THE FRONT. MEANWHILE A WEAK SURFACE LOW WILL DEVELOP ALONG
THE FRONT AS IT PUSHES THROUGH THE MIDSOUTH. MODELS ARE INDICATING VERY
STRONG LIFT INVOF THE FRONT AS WELL. AS A RESULT EXPECT A WIDESPREAD
HEAVY RAINFALL OF 2 INCHES TO PERHAPS AS MUCH AS 4 INCHES LOCALLY
ACROSS THE AREA. DUE TO THE RECENT DRY SPELL RIVER LEVELS ARE LOW
AND FLASH FLOOD GUIDANCE VALUES ARE MAXED OUT SO WILL HOLD OFF ON
A FLASH FLOOD WATCH. WILL MENTION LOW LYING/LOCALIZED FLOODING IN
THE HWO. MARGINAL INSTABILITY COMBINED WITH WEAK SHEAR WILL KEEP
THE SEVERE WEATHER THREAT LOW. TEMPS WILL BE COOLER EVERYWHERE
EXCEPT NE MS WHERE RAIN WILL HOLD OFF FOR MUCH OF THE DAY AND
TEMPS WILL APPROACH 90. RAIN WILL BEGIN TO TAPER OFF FROM THE NW
LATER TONIGHT AS THE FRONT...MOISTURE AND LIFT PUSH EAST.

SATURDAY THROUGH MONDAY...NAM AND GFS PUSH THE FRONT THROUGH A FEW
HOURS QUICKER THAN THE ECMWF. AS A RESULT THE ECMWF HAS QUITE A
BIT MORE PRECIP OVER NE MS SATURDAY AM. TOOK A COMPROMISE
SOLUTION. OTHERWISE EXPECT CLEARING SKIES AND COOLER TEMPS UNDER
NORTHERLY WINDS. EXPECT BELOW NORMAL TEMPS FROM SATURDAY THROUGH
SUNDAY NIGHT WITH HIGHS IN THE UPPER 70S EACH DAY AND LOWS DEEP
INTO THE 50S EACH NIGHT. TEMPS WILL BEGIN TO WARM TOWARD
SEASONABLE LEVELS ON MONDAY AS HIGH PRESSURE RETREATS.

MONDAY NIGHT THROUGH TUESDAY NIGHT...PERFORMED MAJOR SURGERY ON
THIS PART OF THE FORECAST. THE OPERATIONAL GFS AND ECMWF BOTH PUSH
A MID LEVEL TROF THROUGH THE REGION THAT PICKS UP A GOOD DEAL OF
MOISTURE FROM THE GULF AND SPREADS RAIN INTO THE MIDSOUTH MONDAY
NIGHT THROUGH TUESDAY NIGHT. GIVEN THE AGREEMENT BETWEEN THE TWO
MODELS AND THE CONFIRMATION FROM THE GFS ENSEMBLES IT IS HARD TO
IGNORE THIS FEATURE. ADDED SLIGHT CHC/CHC POPS DURING THIS PERIOD
FOR A START THOUGH THESE MAY NEED TO BE INCREASED. THIS FEATURE
WILL ALSO KEEP HIGH TEMPS DOWN A FEW DEGREES FROM THE PREVIOUS
FORECAST.

WEDNESDAY AND THURSDAY...UPPER LEVEL RIDGING WILL PUSH INTO THE
MIDSOUTH FROM THE WEST AND TEMPS WILL CLIMB BACK ABOVE NORMAL WITH
LITTLE RAIN.

SJM

&&

.AVIATION...RAIN WILL PREVAIL AT ALL SITES FOR THE MAJORITY OF
THIS TAF CYCLE AS A COLD FRONT SLOWLY MOVES ACROSS THE MIDSOUTH.
VIS WILL LIKELY VARY BETWEEN 2SM AND 5SM AS HEAVIER SHOWERS MOVE
ACROSS THE AREA. WILL KEEP 3-4 SM IN FOR MOST OF THE PERIOD.
REMOVED THE TSRA AT ALL SITES. WE STILL MAY SEE A FEW
STRIKES...BUT DO NOT THINK COVERAGE WILL BE SIGNIFICANT ENOUGH FOR
EVEN TEMPO THUNDER. CIGS WILL BE VARIABLE AS WELL ESPECIALLY AS
THE FRONT PASSES. HOWEVER MOST SITES WILL SEE GRADUAL REDUCTION IN
CIGS TO IFR LEVELS THIS AFTERNOON AND TONIGHT...THEN POSSIBLE SOME
IMPROVEMENT BEHIND THE FRONT. WINDS WILL BE SOUTHERLY...SHIFTING
FROM THE NORTH BETWEEN 6 AND 10 KTS BEHIND THE FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  81  63  79  58 / 100 100  10   0
MKL  82  62  77  50 /  80 100  10  10
JBR  79  59  77  52 / 100  50  10   0
TUP  86  67  79  56 /  60 100  40  10

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

$$








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