000
FXUS63 KFSD 232300
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
600 PM CDT THU MAY 23 2013

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 305 PM CDT THU MAY 23 2013

HIGH PRESSURE ACROSS THE REGION WILL BEGIN TO PUSH OFF TO THE EAST
OVERNIGHT...AND THE MAIN EFFECT FROM THIS WILL BE TO BRING WINDS
AROUND TO A SOUTHEASTERLY DIRECTION IN THE RETURNING SOUTHERLY LOW
LEVEL FLOW ON THE BACKSIDE OF THE HIGH. WILL SEE THE DEVELOPMENT OF
A LOW LEVEL JET OVER WESTERN SOUTH DAKOTA DURING THE NIGHT TIME
HOURS...AND THIS WILL BEGIN TO NUDGE INTO OUR FAR WEST BY FRIDAY
MORNING AS A MID LEVEL SHORTWAVE BEGINS TO TRACK OUT OF THE ROCKIES.
WITH INCREASING MIDLEVEL THETA E ADVECTION VIA THE AFOREMENTIONED
JET AND WEAK ELEVATED INSTABILITY...MAY SEE SHOWERS AND
THUNDERSTORMS DEVELOP IN OUR FAR WEST EARLY FRIDAY MORNING...THEN
PUSH TO THE EAST DURING THE DAY ON FRIDAY AS THE SHORTWAVE AND A
SURFACE WARM LIFT UP OVER THE AREA. WOULD NOT EXPECT ANY SEVERE
STORMS WITH ONLY RELATIVELY WEAK INSTABILITY IN THE MID LEVELS AND
EFFECTIVE SHEAR IN THIS AREA ONLY AROUND 15 TO 20 KTS. FRIDAY WILL
BE A BREEZY DAY WITH WINDS OF AROUND 30 KTS AT THE TOP OF THE MIXED
LAYER AND A TIGHTENING GRADIENT IN OUR WEST AS THE SURFACE LOW
PRESSURE TRACKS OUT OF THE WESTERN HIGH PLAINS. IN TERMS OF
TEMPERATURES...THERMAL PROFILES WILL BEGIN TO WARM FROM THE WEST
TONIGHT...SO WILL SEE LOWS IN THE UPPER 40S THROUGH SOUTH CENTRAL
SOUTH DAKOTA/JAMES RIVER VALLEY...TO COOLER LOWER 40S IN OUR EAST.
IN SPITE OF THE WARMING THERMAL PROFILES...FRIDAYS TEMPERATURES WILL
BE SIMILAR TO TODAY WITH THE CLOUDS AND SHOWERS...TOPPING OUT IN THE
UPPER 60S TO AROUND 70.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 305 PM CDT THU MAY 23 2013

FRIDAY NIGHT IS A BIT OF A MESS TO DECIPHER THROUGH THE MODELS. AN
ELEVATED BAND OF RAIN AND THUNDERSTORMS WILL LIKELY EXIT THE EASTERN
CWA DURING THE EVENING ASSOCIATED WITH SOMETHING CLOSE TO THE
700-750MB LAYER. FROM ABOUT 3Z THROUGH 6Z THE LOW LEVEL JET WILL
CRANK UP AT ABOUT 850MB AND MAY ALLOW FOR MORE THUNDERSTORMS TO
DEVELOP AROUND THE MISSOURI RIVER AND TRACK EASTWARD AND LIKELY
TRACK INTO NORTHWEST IOWA. THE INITIAL ELEVATED BAND WILL LIKELY NOT
HAVE QUITE ENOUGH INSTABILITY OR SHEAR TO PRODUCE ANY SEVERE WEATHER
BUT THE SECOND AREA OF DEVELOPMENT MAY SEE CAP VALUES AROUND 1500
J/KG SO NOT OUT OF THE QUESTION TO PRODUCE SOME HAIL...ESPECIALLY
WITH ABOUT 30 TO 40 KNOTS OF SHEAR. THE FREEZING LEVEL IS AT ABOUT
11000 FEET SO PRETTY AVERAGE FOR THIS TIME OF YEAR. AN INTERESTING
NOTE...THE NAM BUFKIT SOUNDINGS ARE NOT MATCHING UP WITH THE NAM
PLAN VIEW OUTPUT IN AWIPS...RESULTING IN PRETTY BIG DIFFERENCES IN
SHEAR VALUES.

THE SET UP SATURDAY INTO SATURDAY NIGHT MAY POSE A THREAT FOR SEVERE
WEATHER AND POSSIBLY SOME HEAVY RAINFALL. WHILE UPPER LEVEL FLOW ON
THE LATEST RUNS OF THE MODELS HAS INCREASED A BIT...WHICH IS WHAT
BRINGS MORE OF A THREAT FOR SEVERE WEATHER WITH 0 TO 6KM BULK SHEAR
ABOUT 40 TO 45 KNOTS AND A FAIRLY STRONG CAPE GRADIENT ALONG THE
MISSOURI RIVER VALLEY WITH 2500 J/KG CAPES TO THE SOUTH OF THE
BOUNDARY. WHAT ALSO MAKES THIS AN INTERESTING SET UP IS THAT THE
TIMING OF THE WAVE ALLOWS FOR AN INCREASING LOW LEVEL JET THROUGH
THE EVENING SO IF STORMS CAN DEVELOP LATE AFTERNOON ALONG AND
NORTH OF THE BOUNDARY THERE SHOULD BE A STEADY OR INCREASING FEED OF
DEEPER MOISTURE AND BETTER INSTABILITY. RIGHT NOW SURFACE BASED
THUNDERSTORMS APPEAR UNLIKELY WITH A FAIRLY SIGNIFICANT CAP SO
BELIEVE ANY THUNDERSTORMS THAT CAN DEVELOP NORTH OF THE MISSOURI
RIVER WILL BE ELEVATED SO HAIL AND HEAVY RAIN WILL BE THE MAIN
THREATS.

BY SUNDAY THE THREAT FOR THUNDERSTORMS WILL CONTINUE AS BOUNDARY
LOOKS TO LINGER AROUND. WHILE INSTABILITY MAY STILL BE FAIRLY HIGH
AROUND 2000 J/KG IN THE SOUTHERN CWA SHEAR LOOKS TO DROP OFF
CONSIDERABLY. KIND OF A WAIT AND SEE FOR THIS DAY AS WITH CONVECTION
MANY TIMES THE BOUNDARY LOCATIONS WILL BE DEPENDENT UPON THE
CONVECTION OR LACK THEREOF THE PREVIOUS NIGHT. OTHERWISE THE
EXPECTATION IS THAT CLOUD COVER WILL KEEP TEMPERATURES IN CHECK A
BIT AS WILL THE THREAT FOR SHOWERS AND THUNDERSTORMS THROUGH THE
DAY. LOWS MID 50S TO LOWER 60S WITH HIGHS FROM 65 TO 70 IN SOUTHWEST
MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER.

MONDAY THROUGH THURSDAY A VERY UNSETTLED PERIOD WITH THE WEST COAST
TROUGH MOVING INTO THE ROCKIES AND THEN POTENTIALLY ONTO THE PLAINS
LATE IN THE PERIOD. THIS ALLOWS THE GULF TO REMAIN FAIRLY OPEN AND
ANY WAVES THAT EJECT ONTO THE PLAINS WILL HAVE A GOOD CHANCE TO
PRODUCE THUNDERSTORMS. THIS MAKES IT PRETTY DIFFICULT TO PICK ANY
PERIODS OF TRULY DRY WEATHER. SO UNFORTUNATELY WILL HAVE THE CHANCE
FOR THUNDERSTORMS IN PRETTY MUCH EVERY PERIOD. AS THE TROUGH MOVES
ONTO THE PLAINS SHEAR WILL ALSO INCREASE SO THE POTENTIAL FOR SEVERE
WEATHER WILL LIKELY BE A LITTLE HIGHER WITH ANY STORMS THAT CAN
DEVELOP.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM CDT THU MAY 23 2013

VFR THROUGH 24/12Z. 24/12Z-18Z AREAS OF CEILINGS 2-3K FEET AND
VISIBILITIES 3-5SM IN SHRA/TSRA WILL DEVELOP FROM THE WEST IN THE
AREA WEST OF INTERSTATE 29. THESE WILL CONTINUE IN THIS AREA
24/18Z-25/00Z WITH CEILINGS 2-3K FEET POSSIBLY BECOMING
WIDESPREAD. NEAR AND EAST OF INTERSTATE 29 AREAS OF CEILINGS 2-3K
FEET AND VISIBILITIES 3-5SM IN SHRA/TSRA WILL DEVELOP FROM THE
WEST AFTER 24/16Z. SOUTH TO SOUTHEAST SURFACE GUSTS OF 25 TO 30
KNOTS WILL DEVELOP WEST OF INTERSTATE 29 AFTER 24/12Z. GUSTS NEAR
25 KNOTS WILL DEVELOP NEAR AND EAST OF INTERSTATE 29 AFTER 24/15Z.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...JM
LONG TERM...08
AVIATION...

000
FXUS63 KFSD 232026
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
326 PM CDT THU MAY 23 2013

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 305 PM CDT THU MAY 23 2013

HIGH PRESSURE ACROSS THE REGION WILL BEGIN TO PUSH OFF TO THE EAST
OVERNIGHT...AND THE MAIN EFFECT FROM THIS WILL BE TO BRING WINDS
AROUND TO A SOUTHEASTERLY DIRECTION IN THE RETURNING SOUTHERLY LOW
LEVEL FLOW ON THE BACKSIDE OF THE HIGH. WILL SEE THE DEVELOPMENT OF
A LOW LEVEL JET OVER WESTERN SOUTH DAKOTA DURING THE NIGHT TIME
HOURS...AND THIS WILL BEGIN TO NUDGE INTO OUR FAR WEST BY FRIDAY
MORNING AS A MID LEVEL SHORTWAVE BEGINS TO TRACK OUT OF THE ROCKIES.
WITH INCREASING MIDLEVEL THETA E ADVECTION VIA THE AFOREMENTIONED
JET AND WEAK ELEVATED INSTABILITY...MAY SEE SHOWERS AND
THUNDERSTORMS DEVELOP IN OUR FAR WEST EARLY FRIDAY MORNING...THEN
PUSH TO THE EAST DURING THE DAY ON FRIDAY AS THE SHORTWAVE AND A
SURFACE WARM LIFT UP OVER THE AREA. WOULD NOT EXPECT ANY SEVERE
STORMS WITH ONLY RELATIVELY WEAK INSTABILITY IN THE MID LEVELS AND
EFFECTIVE SHEAR IN THIS AREA ONLY AROUND 15 TO 20 KTS. FRIDAY WILL
BE A BREEZY DAY WITH WINDS OF AROUND 30 KTS AT THE TOP OF THE MIXED
LAYER AND A TIGHTENING GRADIENT IN OUR WEST AS THE SURFACE LOW
PRESSURE TRACKS OUT OF THE WESTERN HIGH PLAINS. IN TERMS OF
TEMPERATURES...THERMAL PROFILES WILL BEGIN TO WARM FROM THE WEST
TONIGHT...SO WILL SEE LOWS IN THE UPPER 40S THROUGH SOUTH CENTRAL
SOUTH DAKOTA/JAMES RIVER VALLEY...TO COOLER LOWER 40S IN OUR EAST.
IN SPITE OF THE WARMING THERMAL PROFILES...FRIDAYS TEMPERATURES WILL
BE SIMILAR TO TODAY WITH THE CLOUDS AND SHOWERS...TOPPING OUT IN THE
UPPER 60S TO AROUND 70.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 305 PM CDT THU MAY 23 2013

FRIDAY NIGHT IS A BIT OF A MESS TO DECIPHER THROUGH THE MODELS. AN
ELEVATED BAND OF RAIN AND THUNDERSTORMS WILL LIKELY EXIT THE EASTERN
CWA DURING THE EVENING ASSOCIATED WITH SOMETHING CLOSE TO THE
700-750MB LAYER. FROM ABOUT 3Z THROUGH 6Z THE LOW LEVEL JET WILL
CRANK UP AT ABOUT 850MB AND MAY ALLOW FOR MORE THUNDERSTORMS TO
DEVELOP AROUND THE MISSOURI RIVER AND TRACK EASTWARD AND LIKELY
TRACK INTO NORTHWEST IOWA. THE INITIAL ELEVATED BAND WILL LIKELY NOT
HAVE QUITE ENOUGH INSTABILITY OR SHEAR TO PRODUCE ANY SEVERE WEATHER
BUT THE SECOND AREA OF DEVELOPMENT MAY SEE CAP VALUES AROUND 1500
J/KG SO NOT OUT OF THE QUESTION TO PRODUCE SOME HAIL...ESPECIALLY
WITH ABOUT 30 TO 40 KNOTS OF SHEAR. THE FREEZING LEVEL IS AT ABOUT
11000 FEET SO PRETTY AVERAGE FOR THIS TIME OF YEAR. AN INTERESTING
NOTE...THE NAM BUFKIT SOUNDINGS ARE NOT MATCHING UP WITH THE NAM
PLAN VIEW OUTPUT IN AWIPS...RESULTING IN PRETTY BIG DIFFERENCES IN
SHEAR VALUES.

THE SET UP SATURDAY INTO SATURDAY NIGHT MAY POSE A THREAT FOR SEVERE
WEATHER AND POSSIBLY SOME HEAVY RAINFALL. WHILE UPPER LEVEL FLOW ON
THE LATEST RUNS OF THE MODELS HAS INCREASED A BIT...WHICH IS WHAT
BRINGS MORE OF A THREAT FOR SEVERE WEATHER WITH 0 TO 6KM BULK SHEAR
ABOUT 40 TO 45 KNOTS AND A FAIRLY STRONG CAPE GRADIENT ALONG THE
MISSOURI RIVER VALLEY WITH 2500 J/KG CAPES TO THE SOUTH OF THE
BOUNDARY. WHAT ALSO MAKES THIS AN INTERESTING SET UP IS THAT THE
TIMING OF THE WAVE ALLOWS FOR AN INCREASING LOW LEVEL JET THROUGH
THE EVENING SO IF STORMS CAN DEVELOP LATE AFTERNOON ALONG AND
NORTH OF THE BOUNDARY THERE SHOULD BE A STEADY OR INCREASING FEED OF
DEEPER MOISTURE AND BETTER INSTABILITY. RIGHT NOW SURFACE BASED
THUNDERSTORMS APPEAR UNLIKELY WITH A FAIRLY SIGNIFICANT CAP SO
BELIEVE ANY THUNDERSTORMS THAT CAN DEVELOP NORTH OF THE MISSOURI
RIVER WILL BE ELEVATED SO HAIL AND HEAVY RAIN WILL BE THE MAIN
THREATS.

BY SUNDAY THE THREAT FOR THUNDERSTORMS WILL CONTINUE AS BOUNDARY
LOOKS TO LINGER AROUND. WHILE INSTABILITY MAY STILL BE FAIRLY HIGH
AROUND 2000 J/KG IN THE SOUTHERN CWA SHEAR LOOKS TO DROP OFF
CONSIDERABLY. KIND OF A WAIT AND SEE FOR THIS DAY AS WITH CONVECTION
MANY TIMES THE BOUNDARY LOCATIONS WILL BE DEPENDENT UPON THE
CONVECTION OR LACK THEREOF THE PREVIOUS NIGHT. OTHERWISE THE
EXPECTATION IS THAT CLOUD COVER WILL KEEP TEMPERATURES IN CHECK A
BIT AS WILL THE THREAT FOR SHOWERS AND THUNDERSTORMS THROUGH THE
DAY. LOWS MID 50S TO LOWER 60S WITH HIGHS FROM 65 TO 70 IN SOUTHWEST
MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER.

MONDAY THROUGH THURSDAY A VERY UNSETTLED PERIOD WITH THE WEST COAST
TROUGH MOVING INTO THE ROCKIES AND THEN POTENTIALLY ONTO THE PLAINS
LATE IN THE PERIOD. THIS ALLOWS THE GULF TO REMAIN FAIRLY OPEN AND
ANY WAVES THAT EJECT ONTO THE PLAINS WILL HAVE A GOOD CHANCE TO
PRODUCE THUNDERSTORMS. THIS MAKES IT PRETTY DIFFICULT TO PICK ANY
PERIODS OF TRULY DRY WEATHER. SO UNFORTUNATELY WILL HAVE THE CHANCE
FOR THUNDERSTORMS IN PRETTY MUCH EVERY PERIOD. AS THE TROUGH MOVES
ONTO THE PLAINS SHEAR WILL ALSO INCREASE SO THE POTENTIAL FOR SEVERE
WEATHER WILL LIKELY BE A LITTLE HIGHER WITH ANY STORMS THAT CAN
DEVELOP.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1216 PM CDT THU MAY 23 2013

VFR CONDITIONS WILL PREDOMINATE THROUGH THE TAF PERIOD. INCREASING
SOUTHEASTERLY WINDS ALOFT WILL RESULT IN LOW LEVEL WIND SHEAR AT
KHON LATER TONIGHT. SHOWERS AND THUNDERSTORMS WILL DEVELOP THROUGH
THE JAMES RIVER VALLEY ON FRIDAY MORNING...AND SOUTHEASTERLY WINDS
WILL PICK UP ACROSS THE ENTIRE AREA...GUSTING TO 25 KTS AT TIMES.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...JM
LONG TERM...08
AVIATION...JM

000
FXUS63 KFSD 231720
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1220 PM CDT THU MAY 23 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT THU MAY 23 2013

LIKELY THE BEST DAY OF THE NEXT MANY DAYS WILL OCCUR ACROSS THE
AREA TODAY WITH SHARP RIDGE ALOFT ACROSS THE AREA. EASTERLY TO
NORTHEAST TRAJECTORY OUT OF KEEWATIN HIGH WILL CONTINUE TO INTRODUCE
DRIER AIR AT LOWER LEVELS.  FLOW IS QUITE ANTICYCLONIC AND OVERALL
LARGER SCALE QUITE SUBSIDENT. RECENT PRECIPITATION HAS SATURATED UP
THE SURFACE QUITE A BIT...AND WITH HEATING AND BUILDING OF MIXED
LAYER WOULD EXPECT POTENTIAL FOR A BIT OF FLAT CUMULUS DEVELOPMENT.
LIKELY SOMEWHAT TERRAIN TIED. LARGE SCALE AND ANTICYCLONIC FLOW
SHOULD KEEP CLOUDS FROM GAINING A GREAT DEAL OF DIURNAL COVERAGE...
PROBABLY AN EARLY TO MID  AFTERNOON MAXIMUM IN THE SCATTERED
COVERAGE REALM. GOOD RECOVERY TO TEMPS WITH SUNSHINE TODAY...
MIXING TO MID 60S TO AROUND 70.

PRESSURE GRADIENT GRADUALLY INCREASES ACROSS THE AREA THROUGH THE
OVERNIGHT AS SURFACE RIDGE RETREATS TO THE EAST. RELATIVELY DRY
AIRMASS ACROSS THE AREA SHOULD LEAD TO COOL OVERNIGHT LOWS...WITH
THE COOLEST READINGS IN THE EASTERN CWA WHERE WINDS AND INCREASING
CLOUDS WILL BE LESS OF A FACTOR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 340 AM CDT THU MAY 23 2013

MODELS INDICATE STRONG MOISTURE TRANSPORT IN THE MID LEVELS ON
FRIDAY LEADING TO ELEVATED CONVECTIVE POTENTIAL AS ISENTROPIC LIFT
INCREASES THROUGHOUT THE DAY. MODEL SOUNDINGS INDICATE TALL THIN
CAPE PROFILE...AND WITH RELATIVELY WEAK WIND SHEAR...AM NOT
EXPECTING MUCH IN THE WAY OF SEVERE POTENTIAL. BAND APPEARS TO
GRADUALLY SHIFT TO THE EAST FRIDAY NIGHT...WITH CONVECTIVE
POTENTIAL REORGANIZING TO THE SOUTH AS BETTER INSTABILITY AND
MOISTURE ORGANIZES TO THE SOUTH. MODELS INDICATE WARM FRONT
HANGING ACROSS THE AREA THROUGH THE WEEKEND...MAKING CONVECTION
DIFFICULT TO TIME. AM NOT THINKING THE WEEKEND WILL BE AN ENTIRE
WASHOUT...BUT INSTEAD PERIODIC RAIN CHANCES FAVORING A DIURNAL
TREND. SLIGHTLY BETTER SEVERE POTENTIAL EXISTS ON SATURDAY INTO
SUNDAY...HOWEVER...REALTIVELY WEAK WIND SHEAR SHOULD KEEP SEVERE
POTENTIAL FAIRLY ISOLATED. CONVECTION CHANCES APPEAR TO BE FAIRLY
GOOD SATURDAY NIGHT AS LOW LEVEL JET INCREASES ACROSS THE PLAINS
AND HAVE RAISED POPS SOME OVER GUIDANCE.

FORECAST BECOMES QUITE MUDDY BEYOND SATURDAY NIGHT WITH SHORTWAVES
EMBEDDED IN WEST TO SOUTHWEST FLOW ALOFT. MODELS IN GENERAL SUGGEST
AN ACTIVE PATTERN...WITH EACH OFFERING THEIR OWN FLAVOR ON TIMING
AND LOCATION OF POPS. IN GENERAL...KEPT CHANCE POPS THROUGH THE
PERIOD. IN TERMS OF TEMPERATURES...KEPT TEMPERATURES VERY SIMILAR
TO THE PREVIOUS FORECAST...HOWEVER...OPERATIONAL RUN OF GFS IS
ERRING TOWARDS THE WARMER SIDE OF THE ENSEMBLE...POTENTIALLY
SUGGESTING OPTIMISTIC FORECAST HIGHS FOR THE HOLIDAY WEEKEND INTO

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1216 PM CDT THU MAY 23 2013

VFR CONDITIONS WILL PREDOMINATE THROUGH THE TAF PERIOD. INCREASING
SOUTHEASTERLY WINDS ALOFT WILL RESULT IN LOW LEVEL WIND SHEAR AT
KHON LATER TONIGHT. SHOWERS AND THUNDERSTORMS WILL DEVELOP THROUGH
THE JAMES RIVER VALLEY ON FRIDAY MORNING...AND SOUTHEASTERLY WINDS
WILL PICK UP ACROSS THE ENTIRE AREA...GUSTING TO 25 KTS AT TIMES.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...JM

000
FXUS63 KFSD 231139
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
639 AM CDT THU MAY 23 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT THU MAY 23 2013

LIKELY THE BEST DAY OF THE NEXT MANY DAYS WILL OCCUR ACROSS THE
AREA TODAY WITH SHARP RIDGE ALOFT ACROSS THE AREA. EASTERLY TO
NORTHEAST TRAJECTORY OUT OF KEEWATIN HIGH WILL CONTINUE TO INTRODUCE
DRIER AIR AT LOWER LEVELS.  FLOW IS QUITE ANTICYCLONIC AND OVERALL
LARGER SCALE QUITE SUBSIDENT. RECENT PRECIPITATION HAS SATURATED UP
THE SURFACE QUITE A BIT...AND WITH HEATING AND BUILDING OF MIXED
LAYER WOULD EXPECT POTENTIAL FOR A BIT OF FLAT CUMULUS DEVELOPMENT.
LIKELY SOMEWHAT TERRAIN TIED. LARGE SCALE AND ANTICYCLONIC FLOW
SHOULD KEEP CLOUDS FROM GAINING A GREAT DEAL OF DIURNAL COVERAGE...
PROBABLY AN EARLY TO MID  AFTERNOON MAXIMUM IN THE SCATTERED
COVERAGE REALM. GOOD RECOVERY TO TEMPS WITH SUNSHINE TODAY...
MIXING TO MID 60S TO AROUND 70.

PRESSURE GRADIENT GRADUALLY INCREASES ACROSS THE AREA THROUGH THE
OVERNIGHT AS SURFACE RIDGE RETREATS TO THE EAST. RELATIVELY DRY
AIRMASS ACROSS THE AREA SHOULD LEAD TO COOL OVERNIGHT LOWS...WITH
THE COOLEST READINGS IN THE EASTERN CWA WHERE WINDS AND INCREASING
CLOUDS WILL BE LESS OF A FACTOR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 340 AM CDT THU MAY 23 2013

MODELS INDICATE STRONG MOISTURE TRANSPORT IN THE MID LEVELS ON
FRIDAY LEADING TO ELEVATED CONVECTIVE POTENTIAL AS ISENTROPIC LIFT
INCREASES THROUGHOUT THE DAY. MODEL SOUNDINGS INDICATE TALL THIN
CAPE PROFILE...AND WITH RELATIVELY WEAK WIND SHEAR...AM NOT
EXPECTING MUCH IN THE WAY OF SEVERE POTENTIAL. BAND APPEARS TO
GRADUALLY SHIFT TO THE EAST FRIDAY NIGHT...WITH CONVECTIVE
POTENTIAL REORGANIZING TO THE SOUTH AS BETTER INSTABILITY AND
MOISTURE ORGANIZES TO THE SOUTH. MODELS INDICATE WARM FRONT
HANGING ACROSS THE AREA THROUGH THE WEEKEND...MAKING CONVECTION
DIFFICULT TO TIME. AM NOT THINKING THE WEEKEND WILL BE AN ENTIRE
WASHOUT...BUT INSTEAD PERIODIC RAIN CHANCES FAVORING A DIURNAL
TREND. SLIGHTLY BETTER SEVERE POTENTIAL EXISTS ON SATURDAY INTO
SUNDAY...HOWEVER...REALTIVELY WEAK WIND SHEAR SHOULD KEEP SEVERE
POTENTIAL FAIRLY ISOLATED. CONVECTION CHANCES APPEAR TO BE FAIRLY
GOOD SATURDAY NIGHT AS LOW LEVEL JET INCREASES ACROSS THE PLAINS
AND HAVE RAISED POPS SOME OVER GUIDANCE.

FORECAST BECOMES QUITE MUDDY BEYOND SATURDAY NIGHT WITH SHORTWAVES
EMBEDDED IN WEST TO SOUTHWEST FLOW ALOFT. MODELS IN GENERAL SUGGEST
AN ACTIVE PATTERN...WITH EACH OFFERING THEIR OWN FLAVOR ON TIMING
AND LOCATION OF POPS. IN GENERAL...KEPT CHANCE POPS THROUGH THE
PERIOD. IN TERMS OF TEMPERATURES...KEPT TEMPERATURES VERY SIMILAR
TO THE PREVIOUS FORECAST...HOWEVER...OPERATIONAL RUN OF GFS IS
ERRING TOWARDS THE WARMER SIDE OF THE ENSEMBLE...POTENTIALLY
SUGGESTING OPTIMISTIC FORECAST HIGHS FOR THE HOLIDAY WEEKEND INTO

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 638 AM CDT THU MAY 23 2013

WEBCAM AT HURON AIRPORT REVEALS THAT AUTOMATED OBSERVATION HAS
GENERALLY BEEN WELL OFF THIS MORNING...INDICATING AS LOW AS 1/4SM
VISIBILITY AND A 100 FT AGL CEILING AT TIMES...WHEN MUCH LESS
STRICT CONDITIONS HAVE BEEN IN PLAY. AS A RESULT...HAVE WRITTEN
A MUCH MORE OPTIMISTIC TAF FOR KHON...WITH SHALLOW MOISTURE IN
FORECAST SOUNDINGS SUPPORTIVE OF THE FUZZY 3-5SM VISIBILITY
APPARENTLY PRESENT. OTHERWISE...HAVE SOME MVFR CEILINGS ON VERGE
OF EXITING KSUX AREA BY 12Z...AND THIS WILL LEAD TO OVERALL VFR
CONDITIONS THROUGH REMAINDER OF PERIOD. SOME LOW END VFR CLOUDS
WILL DEVELOP AROUND MIDDAY HOURS.  AS SOUTHERLY GRADIENT ALOFT
INCREASES...KHON WILL LIKELY DEVELOP SOME LOW LEVEL WIND SHEAR
CONDITIONS AFTER 06Z.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...CHAPMAN

000
FXUS63 KFSD 230917
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
417 AM CDT THU MAY 23 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT THU MAY 23 2013

LIKELY THE BEST DAY OF THE NEXT MANY DAYS WILL OCCUR ACROSS THE
AREA TODAY WITH SHARP RIDGE ALOFT ACROSS THE AREA. EASTERLY TO
NORTHEAST TRAJECTORY OUT OF KEEWATIN HIGH WILL CONTINUE TO INTRODUCE
DRIER AIR AT LOWER LEVELS.  FLOW IS QUITE ANTICYCLONIC AND OVERALL
LARGER SCALE QUITE SUBSIDENT. RECENT PRECIPITATION HAS SATURATED UP
THE SURFACE QUITE A BIT...AND WITH HEATING AND BUILDING OF MIXED
LAYER WOULD EXPECT POTENTIAL FOR A BIT OF FLAT CUMULUS DEVELOPMENT.
LIKELY SOMEWHAT TERRAIN TIED. LARGE SCALE AND ANTICYCLONIC FLOW
SHOULD KEEP CLOUDS FROM GAINING A GREAT DEAL OF DIURNAL COVERAGE...
PROBABLY AN EARLY TO MID  AFTERNOON MAXIMUM IN THE SCATTERED
COVERAGE REALM. GOOD RECOVERY TO TEMPS WITH SUNSHINE TODAY...
MIXING TO MID 60S TO AROUND 70.

PRESSURE GRADIENT GRADUALLY INCREASES ACROSS THE AREA THROUGH THE
OVERNIGHT AS SURFACE RIDGE RETREATS TO THE EAST. RELATIVELY DRY
AIRMASS ACROSS THE AREA SHOULD LEAD TO COOL OVERNIGHT LOWS...WITH
THE COOLEST READINGS IN THE EASTERN CWA WHERE WINDS AND INCREASING
CLOUDS WILL BE LESS OF A FACTOR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 340 AM CDT THU MAY 23 2013

MODELS INDICATE STRONG MOISTURE TRANSPORT IN THE MID LEVELS ON
FRIDAY LEADING TO ELEVATED CONVECTIVE POTENTIAL AS ISENTROPIC LIFT
INCREASES THROUGHOUT THE DAY. MODEL SOUNDINGS INDICATE TALL THIN
CAPE PROFILE...AND WITH RELATIVELY WEAK WIND SHEAR...AM NOT
EXPECTING MUCH IN THE WAY OF SEVERE POTENTIAL. BAND APPEARS TO
GRADUALLY SHIFT TO THE EAST FRIDAY NIGHT...WITH CONVECTIVE
POTENTIAL REORGANIZING TO THE SOUTH AS BETTER INSTABILITY AND
MOISTURE ORGANIZES TO THE SOUTH. MODELS INDICATE WARM FRONT
HANGING ACROSS THE AREA THROUGH THE WEEKEND...MAKING CONVECTION
DIFFICULT TO TIME. AM NOT THINKING THE WEEKEND WILL BE AN ENTIRE
WASHOUT...BUT INSTEAD PERIODIC RAIN CHANCES FAVORING A DIURNAL
TREND. SLIGHTLY BETTER SEVERE POTENTIAL EXISTS ON SATURDAY INTO
SUNDAY...HOWEVER...REALTIVELY WEAK WIND SHEAR SHOULD KEEP SEVERE
POTENTIAL FAIRLY ISOLATED. CONVECTION CHANCES APPEAR TO BE FAIRLY
GOOD SATURDAY NIGHT AS LOW LEVEL JET INCREASES ACROSS THE PLAINS
AND HAVE RAISED POPS SOME OVER GUIDANCE.

FORECAST BECOMES QUITE MUDDY BEYOND SATURDAY NIGHT WITH SHORTWAVES
EMBEDDED IN WEST TO SOUTHWEST FLOW ALOFT. MODELS IN GENERAL SUGGEST
AN ACTIVE PATTERN...WITH EACH OFFERING THEIR OWN FLAVOR ON TIMING
AND LOCATION OF POPS. IN GENERAL...KEPT CHANCE POPS THROUGH THE
PERIOD. IN TERMS OF TEMPERATURES...KEPT TEMPERATURES VERY SIMILAR
TO THE PREVIOUS FORECAST...HOWEVER...OPERATIONAL RUN OF GFS IS
ERRING TOWARDS THE WARMER SIDE OF THE ENSEMBLE...POTENTIALLY
SUGGESTING OPTIMISTIC FORECAST HIGHS FOR THE HOLIDAY WEEKEND INTO
EARLY NEXT WEEK.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1023 PM CDT WED MAY 22 2013

VFR CONDITIONS WILL CONTINUE TO PRESS SOUTHWARD ACROSS THE SIOUX
FALLS FORECAST AREA FOR THE REST OF TONIGHT. BEFORE THE
CLEARING HOWEVER...EXPECT WIDESPREAD MVFR TO UPPER END IFR
CEILINGS. IN ADDITION...A SURFACE RIDGE AXIS WILL SETUP EXTENDING
FROM CENTRAL SOUTH DAKOTA TO NORTHEAST SOUTH DAKOTA. BECAUSE OF
THIS...THE WINDS WILL GO PRETTY LIGHT IN OUR NORTHWEST ZONES...
INCLUDING THE KHON TAF SITE...WHICH COULD SETUP SOME MVFR TO IFR
FOG AROUND SUNRISE IN THAT LOCATION OVER THE WET GROUND. THURSDAY
WILL ALSO BE VFR...BUT SOME STRATOCUMULUS CLOUDS COULD FORM IN THE
MIDDLE OF THE DAY CAUSING SOME BROKEN CEILINGS...STILL IN THE
LOWER VFR CATEGORY.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...

000
FXUS63 KFSD 230324
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1024 PM CDT WED MAY 22 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED MAY 22 2013

UPPER LOW FINALLY DEPARTING THE REGION TO THE SOUTHEAST AND
CURRENTLY LOCATED OVER THE IA/MN/WI STATE LINES PER WATER VAPOR
IMAGERY. HOWEVER...A VORT MAX ON THE WEST SIDE OF THE LOW /CURRENTLY
OVER THE TRI-STATE AREA/ WILL CONTINUE TO GENERATE SHOWERS THIS
AFTERNOON/EVENING...SLOWLY ENDING FROM WEST TO EAST AS THE UPPER LOW
AND VORT MAX BOTH SINK SOUTHEAST. NO FOCUSED MESOSCALE FORCING LOOKS
PRESENT...AS SHOWERS ARE SYNOPTICALLY DRIVEN...SO ONLY LIGHT SHOWERS
ARE EXPECTED THROUGH THIS AFTERNOON/EARLY EVENING.
OVERNIGHT...AIRMASS DRYING WORKS FROM MID/UPPER LEVELS DOWN AND
ADVECTS SOUTH ACROSS THE FORECAST AREA. LOW LEVEL WINDS WILL VEER TO
EAST-NORTHEAST AS TROUGH MOVES SOUTHWARD. THIS WINDS DIRECTION
TYPICAL FAVORS LINGERING MOISTURE/STRATUS...HOWEVER...WITH SUCH
EXTRAORDINARY DRY AIRMASS IN MID-LEVELS/AS SEEN ON WATER VAPOR OVER
ND AND NW MN/...EXPECT THAT SCOURING OUT THE STRATUS SHOULD NOT BE
AN ISSUE. LIGHT WINDS AND RECENT RAINS WILL LIKELY RESULT IN SOME
RADIATIONAL FOG LATE TONIGHT WHERE CLEARING OCCURS FIRST...AND HAVE
EXPANDED FOG COVERAGE FOR LATE TONIGHT ACROSS THE AREA. AFTER A COOL
NIGHT...TEMPERATURES WILL BEGIN TO REBOUND THURSDAY AS UPPER RIDGING
AMPLIFIES AND WARM AIR ADVECTION SETS IN FOR THE AFTERNOON. WILL
ALSO HAVE PLENTY OF SUNSHINE /MAYBE A FEW CU/ AND A DRY AIRMASS IN
PLACE AS HIGH PRESSURE AXIS BUILDS ACROSS THE UPPER MIDWEST. H85
TEMPS INCREASE TO 5 TO 10 C FROM EAST TO WEST ACROSS THE FORECAST
AREA BY 00Z FRIDAY. DESPITE THIS WARM-UP...TEMPS STILL WILL AVERAGE
NEARLY 5 DEGREES BELOW NORMAL FOR HIGHS THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED MAY 22 2013

FRIDAY WILL SEE A HUGE CHANGEOVER ALOFT AS DEW POINTS AROUND 700MB
AT ABOUT -40 DEGREES C THURSDAY NIGHT WILL INCREASE TO ABOUT +5
DEGREES C BY FRIDAYS AFTERNOON. WITH 700MB TO 500MB LAPSE RATES ALSO
RUNNING ABOUT 7 DEGREES OR SO...A BIT TOUGH TO GAGE AS
PRECIPITATION BREAKS OUT IN THE MODEL...THERE SHOULD BE A DECENT
CHANCE FOR AN ELEVATED BAND OF SHOWERS AND THUNDERSTORMS TO DEVELOP.
WILL CONTINUE WITH SOME MID RANGE POPS BUT MAYBE INCREASE JUST A
BIT. ELEVATED CAPE FROM AROUND 750MB TO 700MB RUNNING ABOUT 500 TO
700 J/KG WHICH SUPPORTS THUNDER CHANCES.

SATURDAY LOOKS LIKE A BIT OF A BREEZY DAY AS A WARM FRONT BECOMES
ESTABLISHED OVER THE SOUTHERN CWA INTO PARTS OF NORTHERN NEBRASKA. A
DECENT AMOUNT OF INSTABILITY LOW LEVEL SHEAR EXISTS BUT WINDS ALOFT
NOT VERY SUPPORTIVE OF ORGANIZED CONVECTION. NOT TO MENTION CAPPING
LOOKS PRETTY STRONG AND CONVECTION WILL LIKELY NEED TO DEVELOP
OUTSIDE OF THE AREA AND ADVECT IN. WILL DECREASE POPS A IT ON THE
NORTH THINKING CAPPING WILL HAVE EVERYTHING SHUT DOWN.

NO EASY ANSWERS FOR SUNDAY INTO WEDNESDAY AS A BOUNDARY LOOKS TO
LINGER AROUND MUCH OF THE TIME. RELATIVELY WEAK UPPER LEVEL FLOW
SHOULD PRECLUDE ANY MAJOR SEVERE WEATHER OUTBREAKS SUNDAY INTO
MONDAY BUT ENOUGH LOW LEVEL SHEAR AND INSTABILITY TO PROMOTE THE
POSSIBILITY FOR A FEW SEVERE STORMS. AS WE MOVE INTO TUESDAY AND
WEDNESDAY THE MODELS BEGIN TO SHIFT THE FASTER SOUTHWEST FLOW ALOFT
ONTO THE NORTHERN AND CENTRAL PLAINS WHICH IF WE STILL HAVE A
BOUNDARY AROUND THERE MAY BE A BETTER CHANCE FOR SEVERE
THUNDERSTORMS WITH DEEPER ENHANCED SHEAR. OTHERWISE...THE ECMWF
CONTINUES TO LOCK IN THE COOLER AIR SUNDAY AND MONDAY MORE SO THAN
THE GFS AND GEM. TUESDAY AND WEDNESDAY WILL SEE A BETTER CHANCE FOR
WARMER CONDITIONS AND WITH THE LOW LEVEL RIDGE IN THE SOUTH
SHIFTING EAST THE GULF OPENS UP A LOT MORE AND DEEPER MOISTURE WILL
LIKELY EXIST. WILL UNFORTUNATELY HAVE POPS IN EVERY DAY BUT LEANING
TOWARDS BETTER CHANCES SOUTH SUNDAY AND MONDAY THEN ANYWHERE TUESDAY
AND WEDNESDAY...MAYBE A LITTLE BETTER IN THE EASTERN TWO THIRDS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1023 PM CDT WED MAY 22 2013

VFR CONDITIONS WILL CONTINUE TO PRESS SOUTHWARD ACROSS THE SIOUX
FALLS FORECAST AREA FOR THE REST OF TONIGHT. BEFORE THE
CLEARING HOWEVER...EXPECT WIDESPREAD MVFR TO UPPER END IFR
CEILINGS. IN ADDITION...A SURFACE RIDGE AXIS WILL SETUP EXTENDING
FROM CENTRAL SOUTH DAKOTA TO NORTHEAST SOUTH DAKOTA. BECAUSE OF
THIS...THE WINDS WILL GO PRETTY LIGHT IN OUR NORTHWEST ZONES...
INCLUDING THE KHON TAF SITE...WHICH COULD SETUP SOME MVFR TO IFR
FOG AROUND SUNRISE IN THAT LOCATION OVER THE WET GROUND. THURSDAY
WILL ALSO BE VFR...BUT SOME STRATOCUMULUS CLOUDS COULD FORM IN THE
MIDDLE OF THE DAY CAUSING SOME BROKEN CEILINGS...STILL IN THE
LOWER VFR CATEGORY.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...

000
FXUS63 KFSD 222331
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
631 PM CDT WED MAY 22 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED MAY 22 2013

UPPER LOW FINALLY DEPARTING THE REGION TO THE SOUTHEAST AND
CURRENTLY LOCATED OVER THE IA/MN/WI STATE LINES PER WATER VAPOR
IMAGERY. HOWEVER...A VORT MAX ON THE WEST SIDE OF THE LOW /CURRENTLY
OVER THE TRI-STATE AREA/ WILL CONTINUE TO GENERATE SHOWERS THIS
AFTERNOON/EVENING...SLOWLY ENDING FROM WEST TO EAST AS THE UPPER LOW
AND VORT MAX BOTH SINK SOUTHEAST. NO FOCUSED MESOSCALE FORCING LOOKS
PRESENT...AS SHOWERS ARE SYNOPTICALLY DRIVEN...SO ONLY LIGHT SHOWERS
ARE EXPECTED THROUGH THIS AFTERNOON/EARLY EVENING.
OVERNIGHT...AIRMASS DRYING WORKS FROM MID/UPPER LEVELS DOWN AND
ADVECTS SOUTH ACROSS THE FORECAST AREA. LOW LEVEL WINDS WILL VEER TO
EAST-NORTHEAST AS TROUGH MOVES SOUTHWARD. THIS WINDS DIRECTION
TYPICAL FAVORS LINGERING MOISTURE/STRATUS...HOWEVER...WITH SUCH
EXTRAORDINARY DRY AIRMASS IN MID-LEVELS/AS SEEN ON WATER VAPOR OVER
ND AND NW MN/...EXPECT THAT SCOURING OUT THE STRATUS SHOULD NOT BE
AN ISSUE. LIGHT WINDS AND RECENT RAINS WILL LIKELY RESULT IN SOME
RADIATIONAL FOG LATE TONIGHT WHERE CLEARING OCCURS FIRST...AND HAVE
EXPANDED FOG COVERAGE FOR LATE TONIGHT ACROSS THE AREA. AFTER A COOL
NIGHT...TEMPERATURES WILL BEGIN TO REBOUND THURSDAY AS UPPER RIDGING
AMPLIFIES AND WARM AIR ADVECTION SETS IN FOR THE AFTERNOON. WILL
ALSO HAVE PLENTY OF SUNSHINE /MAYBE A FEW CU/ AND A DRY AIRMASS IN
PLACE AS HIGH PRESSURE AXIS BUILDS ACROSS THE UPPER MIDWEST. H85
TEMPS INCREASE TO 5 TO 10 C FROM EAST TO WEST ACROSS THE FORECAST
AREA BY 00Z FRIDAY. DESPITE THIS WARM-UP...TEMPS STILL WILL AVERAGE
NEARLY 5 DEGREES BELOW NORMAL FOR HIGHS THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED MAY 22 2013

FRIDAY WILL SEE A HUGE CHANGEOVER ALOFT AS DEW POINTS AROUND 700MB
AT ABOUT -40 DEGREES C THURSDAY NIGHT WILL INCREASE TO ABOUT +5
DEGREES C BY FRIDAYS AFTERNOON. WITH 700MB TO 500MB LAPSE RATES ALSO
RUNNING ABOUT 7 DEGREES OR SO...A BIT TOUGH TO GAUGE AS
PRECIPITATION BREAKS OUT IN THE MODEL...THERE SHOULD BE A DECENT
CHANCE FOR AN ELEVATED BAND OF SHOWERS AND THUNDERSTORMS TO DEVELOP.
WILL CONTINUE WITH SOME MID RANGE POPS BUT MAYBE INCREASE JUST A
BIT. ELEVATED CAPE FROM AROUND 750MB TO 700MB RUNNING ABOUT 500 TO
700 J/KG WHICH SUPPORTS THUNDER CHANCES.

SATURDAY LOOKS LIKE A BIT OF A BREEZY DAY AS A WARM FRONT BECOMES
ESTABLISHED OVER THE SOUTHERN CWA INTO PARTS OF NORTHERN NEBRASKA. A
DECENT AMOUNT OF INSTABILITY LOW LEVEL SHEAR EXISTS BUT WINDS ALOFT
NOT VERY SUPPORTIVE OF ORGANIZED CONVECTION. NOT TO MENTION CAPPING
LOOKS PRETTY STRONG AND CONVECTION WILL LIKELY NEED TO DEVELOP
OUTSIDE OF THE AREA AND ADVECT IN. WILL DECREASE POPS A IT ON THE
NORTH THINKING CAPPING WILL HAVE EVERYTHING SHUT DOWN.

NO EASY ANSWERS FOR SUNDAY INTO WEDNESDAY AS A BOUNDARY LOOKS TO
LINGER AROUND MUCH OF THE TIME. RELATIVELY WEAK UPPER LEVEL FLOW
SHOULD PRECLUDE ANY MAJOR SEVERE WEATHER OUTBREAKS SUNDAY INTO
MONDAY BUT ENOUGH LOW LEVEL SHEAR AND INSTABILITY TO PROMOTE THE
POSSIBILITY FOR A FEW SEVERE STORMS. AS WE MOVE INTO TUESDAY AND
WEDNESDAY THE MODELS BEGIN TO SHIFT THE FASTER SOUTHWEST FLOW ALOFT
ONTO THE NORTHERN AND CENTRAL PLAINS WHICH IF WE STILL HAVE A
BOUNDARY AROUND THERE MAY BE A BETTER CHANCE FOR SEVERE
THUNDERSTORMS WITH DEEPER ENHANCED SHEAR. OTHERWISE...THE ECMWF
CONTINUES TO LOCK IN THE COOLER AIR SUNDAY AND MONDAY MORE SO THAN
THE GFS AND GEM. TUESDAY AND WEDNESDAY WILL SEE A BETTER CHANCE FOR
WARMER CONDITIONS AND WITH THE LOW LEVEL RIDGE IN THE SOUTH
SHIFTING EAST THE GULF OPENS UP A LOT MORE AND DEEPER MOISTURE WILL
LIKELY EXIST. WILL UNFORTUNATELY HAVE POPS IN EVERY DAY BUT LEANING
TOWARDS BETTER CHANCES SOUTH SUNDAY AND MONDAY THEN ANYWHERE TUESDAY
AND WEDNESDAY...MAYBE A LITTLE BETTER IN THE EASTERN TWO THIRDS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 630 PM CDT WED MAY 22 2013

MVFR CONDITIONS WITH SOME LOCALIZED IFR WILL GRADUALLY ERODE
SOUTHWARD THROUGH TONIGHT. BEHIND THE STRATUS...VFR CONDITIONS
SHOULD TAKE HOLD BUT THERE IS ONE CAVEAT. A SURFACE HIGH PRESSURE
RIDGE AXIS WILL EXTEND FROM CENTRAL SD TO CENTRAL MN BY LATE
TONIGHT AND EARLY THURSDAY. THEREFORE THE WINDS WILL LIKELY GO
VERY LIGHT IN OUR NORTHWEST ZONES INCLUDING THE KHON TAF. WITH THE
MOIST GROUND...AM WORRIED ABOUT FOG POTENTIAL LATE TONIGHT AND
EARLY THURSDAY FOR THOSE AREAS...SO KEPT THE MENTION OF SOME IFR
VISIBILITIES FOR KHON. OTHERWISE VFR SHOULD PREVAIL FOR MOST AREAS
ON THURSDAY. WOULD NOT BE SURPRISED TO SEE SOME SCATTERED TO
BROKEN CEILINGS FROM EVAPORATION OFF OF WET GROUND IN THE LATE
MORNING AND AFTERNOON. BUT LATEST NAM MODEL SOUNDINGS SHOW THAT
ANY BROKEN CEILINGS SHOULD BE IN THE LOWER VFR CATEGORY.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...MJF

000
FXUS63 KFSD 222007
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
307 PM CDT WED MAY 22 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED MAY 22 2013

UPPER LOW FINALLY DEPARTING THE REGION TO THE SOUTHEAST AND
CURRENTLY LOCATED OVER THE IA/MN/WI STATE LINES PER WATER VAPOR
IMAGERY. HOWEVER...A VORT MAX ON THE WEST SIDE OF THE LOW /CURRENTLY
OVER THE TRI-STATE AREA/ WILL CONTINUE TO GENERATE SHOWERS THIS
AFTERNOON/EVENING...SLOWLY ENDING FROM WEST TO EAST AS THE UPPER LOW
AND VORT MAX BOTH SINK SOUTHEAST. NO FOCUSED MESOSCALE FORCING LOOKS
PRESENT...AS SHOWERS ARE SYNOPTICALLY DRIVEN...SO ONLY LIGHT SHOWERS
ARE EXPECTED THROUGH THIS AFTERNOON/EARLY EVENING.
OVERNIGHT...AIRMASS DRYING WORKS FROM MID/UPPER LEVELS DOWN AND
ADVECTS SOUTH ACROSS THE FORECAST AREA. LOW LEVEL WINDS WILL VEER TO
EAST-NORTHEAST AS TROUGH MOVES SOUTHWARD. THIS WINDS DIRECTION
TYPICAL FAVORS LINGERING MOISTURE/STRATUS...HOWEVER...WITH SUCH
EXTRAORDINARY DRY AIRMASS IN MID-LEVELS/AS SEEN ON WATER VAPOR OVER
ND AND NW MN/...EXPECT THAT SCOURING OUT THE STRATUS SHOULD NOT BE
AN ISSUE. LIGHT WINDS AND RECENT RAINS WILL LIKELY RESULT IN SOME
RADIATIONAL FOG LATE TONIGHT WHERE CLEARING OCCURS FIRST...AND HAVE
EXPANDED FOG COVERAGE FOR LATE TONIGHT ACROSS THE AREA. AFTER A COOL
NIGHT...TEMPERATURES WILL BEGIN TO REBOUND THURSDAY AS UPPER RIDGING
AMPLIFIES AND WARM AIR ADVECTION SETS IN FOR THE AFTERNOON. WILL
ALSO HAVE PLENTY OF SUNSHINE /MAYBE A FEW CU/ AND A DRY AIRMASS IN
PLACE AS HIGH PRESSURE AXIS BUILDS ACROSS THE UPPER MIDWEST. H85
TEMPS INCREASE TO 5 TO 10 C FROM EAST TO WEST ACROSS THE FORECAST
AREA BY 00Z FRIDAY. DESPITE THIS WARM-UP...TEMPS STILL WILL AVERAGE
NEARLY 5 DEGREES BELOW NORMAL FOR HIGHS THURSDAY.


.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED MAY 22 2013

FRIDAY WILL SEE A HUGE CHANGEOVER ALOFT AS DEW POINTS AROUND 700MB
AT ABOUT -40 DEGREES C THURSDAY NIGHT WILL INCREASE TO ABOUT +5
DEGREES C BY FRIDAYS AFTERNOON. WITH 700MB TO 500MB LAPSE RATES ALSO
RUNNING ABOUT 7 DEGREES OR SO...A BIT TOUGH TO GAUGE AS
PRECIPITATION BREAKS OUT IN THE MODEL...THERE SHOULD BE A DECENT
CHANCE FOR AN ELEVATED BAND OF SHOWERS AND THUNDERSTORMS TO DEVELOP.
WILL CONTINUE WITH SOME MID RANGE POPS BUT MAYBE INCREASE JUST A
BIT. ELEVATED CAPE FROM AROUND 750MB TO 700MB RUNNING ABOUT 500 TO
700 J/KG WHICH SUPPORTS THUNDER CHANCES.

SATURDAY LOOKS LIKE A BIT OF A BREEZY DAY AS A WARM FRONT BECOMES
ESTABLISHED OVER THE SOUTHERN CWA INTO PARTS OF NORTHERN NEBRASKA. A
DECENT AMOUNT OF INSTABILITY LOW LEVEL SHEAR EXISTS BUT WINDS ALOFT
NOT VERY SUPPORTIVE OF ORGANIZED CONVECTION. NOT TO MENTION CAPPING
LOOKS PRETTY STRONG AND CONVECTION WILL LIKELY NEED TO DEVELOP
OUTSIDE OF THE AREA AND ADVECT IN. WILL DECREASE POPS A IT ON THE
NORTH THINKING CAPPING WILL HAVE EVERYTHING SHUT DOWN.

NO EASY ANSWERS FOR SUNDAY INTO WEDNESDAY AS A BOUNDARY LOOKS TO
LINGER AROUND MUCH OF THE TIME. RELATIVELY WEAK UPPER LEVEL FLOW
SHOULD PRECLUDE ANY MAJOR SEVERE WEATHER OUTBREAKS SUNDAY INTO
MONDAY BUT ENOUGH LOW LEVEL SHEAR AND INSTABILITY TO PROMOTE THE
POSSIBILITY FOR A FEW SEVERE STORMS. AS WE MOVE INTO TUESDAY AND
WEDNESDAY THE MODELS BEGIN TO SHIFT THE FASTER SOUTHWEST FLOW ALOFT
ONTO THE NORTHERN AND CENTRAL PLAINS WHICH IF WE STILL HAVE A
BOUNDARY AROUND THERE MAY BE A BETTER CHANCE FOR SEVERE
THUNDERSTORMS WITH DEEPER ENHANCED SHEAR. OTHERWISE...THE ECMWF
CONTINUES TO LOCK IN THE COOLER AIR SUNDAY AND MONDAY MORESO THAN
THE GFS AND GEM. TUESDAY AND WEDNESDAY WILL SEE A BETTER CHANCE FOR
WARMER CONDITIONS AND WITH THE LOW LEVEL RIDGE IN THE SOUTH
SHIFTING EAST THE GULF OPENS UP A LOT MORE AND DEEPER MOISTURE WILL
LIKELY EXIST. WILL UNFORTUNATELY HAVE POPS IN EVERY DAY BUT LEANING
TOWARDS BETTER CHANCES SOUTH SUNDAY AND MONDAY THEN ANYWHERE TUESDAY
AND WEDNESDAY...MAYBE A LITTLE BETTER IN THE EASTERN TWO THIRDS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1223 PM CDT WED MAY 22 2013

WIDESPREAD MVFR CIGS THIS EARLY AFTERNOON ALONG WITH SCT TO
NUMEROUS SHOWERS WILL CONTINUE THROUGH LATE AFTERNOON. SHOWERS
WILL DIMINISH FROM WEST TO EAST THIS EVENING TONIGHT ALTHOUGH LOW
LEVEL MOISTURE WILL REMAIN IN PLACE. IFR CIGS ARE EXPECTED
TO REDEVELOP WITH DECOUPLING LATER THIS EVENING AT SUX/FSD.
CLEARING IS EXPECTED TO PUSH IN FROM THE NORTH OVERNIGHT FIRST AT
HON AND THEN FSD...HOWEVER RESIDUAL MOISTURE WILL LIKELY RESULT IN
SOME AREAS OF RADIATIONAL BR/FG...ESPECIALLY IN HON VICINITY.
CLEARING OF LOW LEVEL STRATUS MAY ALSO OCCUR SLOWER THAN FORECAST
BY A FEW HOURS DUE TO VEERING WINDS IN A MOISTURE FAVORED ENE
DIRECTION. HOWEVER...BEFORE THE END OF THE TAF
PERIOD...HON/FSD/SUX SITES SHOULD ALL BE VFR.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...

000
FXUS63 KFSD 221723
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1223 PM CDT WED MAY 22 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT WED MAY 22 2013

UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE AREA EARLY THIS
MORNING...FAIRLY CLOSE TO KYKN...BUT WITH SOME UNCERTAINTY GIVEN
WHAT IS HOPEFULLY A TEMPORARY LOSS OF THE GOES-EAST DATA DUE TO
LATE EVENING MALFUNCTION /ESTIMATED RETURN TOWARD 18Z TODAY/.
BULK OF PRECIPITATION CONTINUING TO OCCUR JUST ON BACK SIDE OF THE
MID LEVEL CENTER WHERE TENDENCY TO FOCUS A BIT OF LOWER TO MID LEVEL
FRONTOGENESIS AND ISENTROPIC LIFT IN THE 295-300K LAYER. RETURNS
HAVE REALLY VARIED OVERNIGHT...SOMETIMES NEARLY DISSIPATING...ONLY
TO REFORM AND BECOME QUITE WIDESPREAD JUST AN HOUR LATER. AT CURRENT
TIME...ABOUT THE BEST COVERAGE OF THE NIGHT SO FAR ALONG AND WEST OF
I29 AS PULSE IN THE ISENTROPIC LIFT WORKS WESTWARD NORTH OF THE
CYCLONE CENTER. TREATING LIKE A CLASSIC HIGH POP/LOW QPF EVENT AT
LEAST THROUGH THE EARLY MORNING HOURS...WITH SIGNS IN SEVERAL MODELS
OF A WEAKENING OF THIS TROWAL-LIKE FEATURE THROUGH THE MORNING...
BUT PERHAPS A RESURGENCE IN COVERAGE BY EARLY TO MID AFTERNOON NEAR
AND JUST E OF I29 IF SOLUTIONS TAKEN LITERALLY. GENERALLY...EXPECT A
DAY WITH OCCASIONAL SHOWERS...STARTING TO DWINDLE FROM THE WEST. NOT
EXPECTING TO SEE MUCH IN THE WAY OF CLEARING TODAY...PERHAPS A
PARTIAL BIT LEAKING INTO THE FAR NORTH/NORTHWEST. THUS WITH CLOUDS
AND EXPECTED PRECIPITATION...ANOTHER CHILLY DAY WITH FAIRLY LIMITED
RECOVERY FROM CURRENT READINGS...MEANING HIGHS 10 TO 15 DEGREES
BELOW NORMAL.

PRECIPITATION SHOULD WIND DOWN THROUGH THE EVENING HOURS TONIGHT
AS ISENTROPIC DOWN GLIDE INCREASES ACROSS THE AREA. ADDED MENTION
OF PATCHY FOG ACROSS CENTRAL SOUTH DAKOTA WHERE SKIES CLEAR AND
WINDS DECREASE. CONSIDERED EXPANDING FURTHER EAST...BUT FOG IS
CONDITIONAL ON TIMING OF CLEARING AND WIND POTENTIAL.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 340 AM CDT WED MAY 22 2013

RELATIVELY QUIET WEATHER IS EXPECTED ON THURSDAY WITH SURFACE
RIDGE PASSING THROUGH THE REGION TO THE NORTH. MODELS SUGGEST
RETURN FLOW SETS UP FAIRLY QUICKLY THURSDAY AFTERNOON INTO
THURSDAY NIGHT...THOUGH NO DIRECT TAP TO THE GULF IS PRESENT SO AM
NOT EXPECTING A SUBSTANTIAL INCREASE IN MOISTURE UNTIL FRIDAY NIGHT
INTO SATURDAY WHEN LOW LEVEL JET SETS UP ACROSS THE CENTRAL
PLAINS. MODELS SEEM TO SUGGEST A FAIRLY WEAK CAPPING
INVERSION...WITH THE POTENTIAL FOR STORMS TO DEVELOP AS A LEADING
SHORT WAVE BREAKS OFF UPPER LOW SPINNING ACROSS THE NW US. THE
ECMWF SUGGESTS THE UPPER WAVE MAY SHEAR OUT TO THE NORTH AND WEST
OF THE CWA AS IT TRIES TO WORK EAST INTO THE UPPER RIDGE ACROSS
THE CENTRAL PLAINS...WHILE THE GFS SUGGESTS A SERIES OF PHASED
WAVES TRAVELING ACROSS THE AREA. THE WAVES IN THE GFS SOLUTION
APPEAR TO BE CONVECTIVE DRIVEN...AND HAVE THEREFORE SIDED CLOSER
TO AN ECMWF SOLUTION. WITH THAT SAID...WAS NOT THAT EXCITED ABOUT
PRECIPITATION CHANCES AND LOWERED POPS SLIGHTLY...ESPECIALLY
DURING THE DAY ON FRIDAY. WITH BETTER MOISTURE RETURN FRIDAY
NIGHT...PRECIPITATION CHANCES APPEAR TO BE MORE SIGNIFICANT WITH
LITTLE CAPPING INVERSION FROM A LIFTING LAYER BETWEEN 700-800 MB.

OFF AND ON CHANCES OF PRECIPITATION CONTINUE TO PLAGUE THE
EXTENDED WITH DIRTY WEST TO SOUTHWEST FLOW ALOFT WITH WAVES
BREAKING OFF IN A PIECEMEAL FASHION AND MOVING THROUGH THE PLAINS.
WITH UPPER LOW REMAINING TO THE WEST...LOW LEVEL FLOW REMAINS
SOUTHEAST TO SOUTH THROUGH MUCH OF THE EXTENDED. THIS WILL RESULT
IN AN OVERALL GRADUAL WARMING TREND...ALONG WITH AN INCREASE IN
MOISTURE. WITH LITTLE AGREEMENT ON TIMING OF UPPER WAVES...LEFT
GUIDANCE POPS AS IS WITH CHANCES OF THUNDERSTORMS THROUGHOUT THE
EXTENDED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1223 PM CDT WED MAY 22 2013

WIDESPREAD MVFR CIGS THIS EARLY AFTERNOON ALONG WITH SCT TO
NUMEROUS SHOWERS WILL CONTINUE THROUGH LATE AFTERNOON. SHOWERS
WILL DIMINISH FROM WEST TO EAST THIS EVENING TONIGHT ALTHOUGH LOW
LEVEL MOISTURE WILL REMAIN IN PLACE. IFR CIGS ARE EXPECTED
TO REDEVELOP WITH DECOUPLING LATER THIS EVENING AT SUX/FSD.
CLEARING IS EXPECTED TO PUSH IN FROM THE NORTH OVERNIGHT FIRST AT
HON AND THEN FSD...HOWEVER RESIDUAL MOISTURE WILL LIKELY RESULT IN
SOME AREAS OF RADIATIONAL BR/FG...ESPECIALLY IN HON VICINITY.
CLEARING OF LOW LEVEL STRATUS MAY ALSO OCCUR SLOWER THAN FORECAST
BY A FEW HOURS DUE TO VEERING WINDS IN A MOISTURE FAVORED ENE
DIRECTION. HOWEVER...BEFORE THE END OF THE TAF
PERIOD...HON/FSD/SUX SITES SHOULD ALL BE VFR.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...

000
FXUS63 KFSD 221116
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
616 AM CDT WED MAY 22 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT WED MAY 22 2013

UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE AREA EARLY THIS
MORNING...FAIRLY CLOSE TO KYKN...BUT WITH SOME UNCERTAINTY GIVEN
WHAT IS HOPEFULLY A TEMPORARY LOSS OF THE GOES-EAST DATA DUE TO
LATE EVENING MALFUNCTION /ESTIMATED RETURN TOWARD 18Z TODAY/.
BULK OF PRECIPITATION CONTINUING TO OCCUR JUST ON BACK SIDE OF THE
MID LEVEL CENTER WHERE TENDENCY TO FOCUS A BIT OF LOWER TO MID LEVEL
FRONTOGENESIS AND ISENTROPIC LIFT IN THE 295-300K LAYER. RETURNS
HAVE REALLY VARIED OVERNIGHT...SOMETIMES NEARLY DISSIPATING...ONLY
TO REFORM AND BECOME QUITE WIDESPREAD JUST AN HOUR LATER. AT CURRENT
TIME...ABOUT THE BEST COVERAGE OF THE NIGHT SO FAR ALONG AND WEST OF
I29 AS PULSE IN THE ISENTROPIC LIFT WORKS WESTWARD NORTH OF THE
CYCLONE CENTER. TREATING LIKE A CLASSIC HIGH POP/LOW QPF EVENT AT
LEAST THROUGH THE EARLY MORNING HOURS...WITH SIGNS IN SEVERAL MODELS
OF A WEAKENING OF THIS TROWAL-LIKE FEATURE THROUGH THE MORNING...
BUT PERHAPS A RESURGENCE IN COVERAGE BY EARLY TO MID AFTERNOON NEAR
AND JUST E OF I29 IF SOLUTIONS TAKEN LITERALLY. GENERALLY...EXPECT A
DAY WITH OCCASIONAL SHOWERS...STARTING TO DWINDLE FROM THE WEST. NOT
EXPECTING TO SEE MUCH IN THE WAY OF CLEARING TODAY...PERHAPS A
PARTIAL BIT LEAKING INTO THE FAR NORTH/NORTHWEST. THUS WITH CLOUDS
AND EXPECTED PRECIPITATION...ANOTHER CHILLY DAY WITH FAIRLY LIMITED
RECOVERY FROM CURRENT READINGS...MEANING HIGHS 10 TO 15 DEGREES
BELOW NORMAL.

PRECIPITATION SHOULD WIND DOWN THROUGH THE EVENING HOURS TONIGHT
AS ISENTROPIC DOWN GLIDE INCREASES ACROSS THE AREA. ADDED MENTION
OF PATCHY FOG ACROSS CENTRAL SOUTH DAKOTA WHERE SKIES CLEAR AND
WINDS DECREASE. CONSIDERED EXPANDING FURTHER EAST...BUT FOG IS
CONDITIONAL ON TIMING OF CLEARING AND WIND POTENTIAL.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 340 AM CDT WED MAY 22 2013

RELATIVELY QUIET WEATHER IS EXPECTED ON THURSDAY WITH SURFACE
RIDGE PASSING THROUGH THE REGION TO THE NORTH. MODELS SUGGEST
RETURN FLOW SETS UP FAIRLY QUICKLY THURSDAY AFTERNOON INTO
THURSDAY NIGHT...THOUGH NO DIRECT TAP TO THE GULF IS PRESENT SO AM
NOT EXPECTING A SUBSTANTIAL INCREASE IN MOISTURE UNTIL FRIDAY NIGHT
INTO SATURDAY WHEN LOW LEVEL JET SETS UP ACROSS THE CENTRAL
PLAINS. MODELS SEEM TO SUGGEST A FAIRLY WEAK CAPPING
INVERSION...WITH THE POTENTIAL FOR STORMS TO DEVELOP AS A LEADING
SHORT WAVE BREAKS OFF UPPER LOW SPINNING ACROSS THE NW US. THE
ECMWF SUGGESTS THE UPPER WAVE MAY SHEAR OUT TO THE NORTH AND WEST
OF THE CWA AS IT TRIES TO WORK EAST INTO THE UPPER RIDGE ACROSS
THE CENTRAL PLAINS...WHILE THE GFS SUGGESTS A SERIES OF PHASED
WAVES TRAVELING ACROSS THE AREA. THE WAVES IN THE GFS SOLUTION
APPEAR TO BE CONVECTIVE DRIVEN...AND HAVE THEREFORE SIDED CLOSER
TO AN ECMWF SOLUTION. WITH THAT SAID...WAS NOT THAT EXCITED ABOUT
PRECIPITATION CHANCES AND LOWERED POPS SLIGHTLY...ESPECIALLY
DURING THE DAY ON FRIDAY. WITH BETTER MOISTURE RETURN FRIDAY
NIGHT...PRECIPITATION CHANCES APPEAR TO BE MORE SIGNIFICANT WITH
LITTLE CAPPING INVERSION FROM A LIFTING LAYER BETWEEN 700-800 MB.

OFF AND ON CHANCES OF PRECIPITATION CONTINUE TO PLAGUE THE
EXTENDED WITH DIRTY WEST TO SOUTHWEST FLOW ALOFT WITH WAVES
BREAKING OFF IN A PIECEMEAL FASHION AND MOVING THROUGH THE PLAINS.
WITH UPPER LOW REMAINING TO THE WEST...LOW LEVEL FLOW REMAINS
SOUTHEAST TO SOUTH THROUGH MUCH OF THE EXTENDED. THIS WILL RESULT
IN AN OVERALL GRADUAL WARMING TREND...ALONG WITH AN INCREASE IN
MOISTURE. WITH LITTLE AGREEMENT ON TIMING OF UPPER WAVES...LEFT
GUIDANCE POPS AS IS WITH CHANCES OF THUNDERSTORMS THROUGHOUT THE
EXTENDED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 615 AM CDT WED MAY 22 2013

WIDESPREAD MVFR TO IFR CEILINGS EXPECTED FOR MUCH OF THE UPCOMING
PERIOD...WITH VISIBILITIES HAMPERED AT TIMES INTO THE MVFR WITH
LIGHT RAIN/DRIZZLE. GRADUALLY...FORCING FOR LIFT PRODUCING
PRECIPITATION WILL ERODE FROM THE KHON AREA BY LATER IN THE
MORNING...BUT WILL LIKELY PERSIST INTO THE AFTERNOON FOR KFSD/KSUX
AREAS. LIKELY THAT MIDDAY AND AFTERNOON CEILINGS WILL LIFT INTO
MVFR FOR ALL LOCATIONS...BUT SUBSIDENCE IN THE RIDGE AXIS WILL
LIKELY LOWER INVERSION AND THUS CEILINGS BY EARLY THIS EVENING...
WITH SOME IFR CEILINGS EXPECTED TO REDEVELOP FOR KFSD AND KSUX. WILL
BE FAIRLY HARD TO SHAKE STRATUS SOUTH OF INTERSTATE 90 UNTIL VERY
LATE TONIGHT...AS LOW LEVEL FLOW HOLDS ONTO AN EASTERLY COMPONENT.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...CHAPMAN

000
FXUS63 KFSD 220840
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
340 AM CDT WED MAY 22 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 259 AM CDT WED MAY 22 2013

UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE AREA EARLY THIS
MORNING...FAIRLY CLOSE TO KYKN...BUT WITH SOME UNCERTAINTY GIVEN
WHAT IS HOPEFULLY A TEMPORARY LOSS OF THE GOES-EAST DATA DUE TO
LATE EVENING MALFUNCTION /ESTIMATED RETURN TOWARD 18Z TODAY/.
BULK OF PRECIPITATION CONTINUING TO OCCUR JUST ON BACK SIDE OF THE
MID LEVEL CENTER WHERE TENDENDY TO FOCUS A BIT OF LOWER TO MID LEVEL
FRONTOGENESIS AND ISENTROPIC LIFT IN THE 295-300K LAYER. RETURNS
HAVE REALLY VARIED OVERNIGHT...SOMETIMES NEARLY DISSIPATING...ONLY
TO REFORM AND BECOME QUITE WIDESPREAD JUST AN HOUR LATER. AT CURRENT
TIME...ABOUT THE BEST COVERAGE OF THE NIGHT SO FAR ALONG AND WEST OF
I29 AS PULSE IN THE ISENTROPIC LIFT WORKS WESTWARD NORTH OF THE
CYCLONE CENTER. TREATING LIKE A CLASSIC HIGH POP/LOW QPF EVENT AT
LEAST THROUGH THE EARLY MORNING HOURS...WITH SIGNS IN SEVERAL MODELS
OF A WEAKENING OF THIS TROWAL-LIKE FEATURE THROUGH THE MORNING...
BUT PERHAPS A RESURGENCE IN COVERAGE BY EARLY TO MID AFTERNOON NEAR
AND JUST E OF I29 IF SOLUTIONS TAKEN LITERALLY. GENERALLY...EXPECT A
DAY WITH OCCASIONAL SHOWERS...STARTING TO DWINDLE FROM THE WEST. NOT
EXPECTING TO SEE MUCH IN THE WAY OF CLEARING TODAY...PERHAPS A
PARTIAL BIT LEAKING INTO THE FAR NORTH/NORTHWEST. THUS WITH CLOUDS
AND EXPECTED PRECIPITATION...ANOTHER CHILLY DAY WITH FAIRLY LIMITED
RECOVERY FROM CURRENT READINGS...MEANING HIGHS 10 TO 15 DEGREES
BELOW NORMAL.

PRECIPITATION SHOULD WIND DOWN THROUGH THE EVENING HOURS TONIGHT
AS ISENTROPIC DOWN GLIDE INCREASES ACROSS THE AREA. ADDED MENTION
OF PATCHY FOG ACROSS CENTRAL SOUTH DAKOTA WHERE SKIES CLEAR AND
WINDS DECREASE. CONSIDERED EXPANDING FURTHER EAST...BUT FOG IS
CONDITIONAL ON TIMING OF CLEARING AND WIND POTENTIAL.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 259 AM CDT WED MAY 22 2013

RELATIVELY QUIET WEATHER IS EXPECTED ON THURSDAY WITH SURFACE
RIDGE PASSING THROUGH THE REGION TO THE NORTH. MODELS SUGGEST
RETURN FLOW SETS UP FAIRLY QUICKLY THURSDAY AFTERNOON INTO
THURSDAY NIGHT...THOUGH NO DIRECT TAP TO THE GULF IS PRESENT SO AM
NOT EXPECTING A SUBSTATIAL INCREASE IN MOISTURE UNTIL FRIDAY NIGHT
INTO SATURDAY WHEN LOW LEVEL JET SETS UP ACROSS THE CENTRAL
PLAINS. MODELS SEEM TO SUGGES A FAIRLY WEAK CAPPING
INVERSION...WITH THE POTENTIAL FOR STORMS TO DEVELOP AS A LEADING
SHORT WAVE BREAKS OFF UPPER LOW SPINNING ACROSS THE NW US. THE
ECMWF SUGGESTS THE UPPER WAVE MAY SHEAR OUT TO THE NORTH AND WEST
OF THE CWA AS IT TRIES TO WORK EAST INTO THE UPPER RIDGE ACROSS
THE CENTRAL PLAINS...WHILE THE GFS SUGGESTS A SERIES OF PHASED
WAVES TRAVELING ACROSS THE AREA. THE WAVES IN THE GFS SOLUTION
APPEAR TO BE CONVECTIVE DRIVEN...AND HAVE THEREFORE SIDED CLOSER
TO AN ECMWF SOLUTION. WITH THAT SAID...WAS NOT THAT EXCITED ABOUT
PRECIPITATION CHANCES AND LOWERED POPS SLIGHTLY...ESPECIALLY
DURING THE DAY ON FRIDAY. WITH BETTER MOISTURE RETURN FRIDAY
NIGHT...PRECIPITATION CHANCES APPEAR TO BE MORE SIGNIFICAT WITH
LITTLE CAPPING INVERSION FROM A LIFTING LAYER BETWEEN 700-800 MB.

OFF AND ON CHANCES OF PRECIPITATION CONTINUE TO PLAGUE THE
EXTENDED WITH DIRTY WEST TO SOUTHWEST FLOW ALOFT WITH WAVES
BREAKING OFF IN A PIECEMEAL FASHION AND MOVING THROUGH THE PLAINS.
WITH UPPER LOW REMAINING TO THE WEST...LOW LEVEL FLOUW REMAINS
SOUTHEAST TO SOUTH THROUGH MUCH OF THE EXTENDED. THIS WILL RESULT
IN AN OVERALL GRADUAL WARMING TREND...ALONG WITH AN INCREASE IN
MOISTURE. WITH LITTLE AGREEMENT ON TIMING OF UPPER WAVES...LEFT
GUIDANCE POPS AS IS WITH CHANCES OF THUNDERSTORMS THROUGHOUT THE
EXTENDED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 1046 PM CDT TUE MAY 21 2013

ONCE AGAIN...MVFR CONDITIONS WILL LIKELY DOMINATE THE WEATHER
FOR THE REST OF TONIGHT AND WEDNESDAY ALONG AND NORTH OF I
90...WITH MVFR TO LOWER END VFR SOUTH OF I 90. ONE CHALLENGE IN
THIS FORECAST IS THAT THERE WILL PROBABLY BE PATCHES OF DRIZZLE
MOVING THROUGH THE AREA TONIGHT AND WEDNESDAY. DRIZZLE WILL LIKELY
LOWER THE CONDITIONS INTO THE IFR CATEGORY FOR BRIEF PERIODS OF
TIME. HOWEVER...DUE TO THE INTERMITTENT AND SPOTTY NATURE OF THE
DRIZZLE...IT IS EXTREMELY DIFFICULT TO PREDICT THESE EPISODES MUCH
AHEAD OF TIME. THEREFORE SHORT TERM AMENDMENTS TO THE TAFS COULD
OCCUR TO ACCOUNT FOR THESE CONDITIONS.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...CHAPMAN
LONG TERM...
AVIATION...

000
FXUS63 KFSD 220348
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1048 PM CDT TUE MAY 21 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 302 PM CDT TUE MAY 21 2013

UPPER LOW THAT IS DOMINATING THE WEATHER IN THE SHORT TERM IS
CURRENTLY LOCATED OVER NORTHEAST SOUTH DAKOTA PER LATEST WATER VAPOR
IMAGERY. THIS LOW HAS ALREADY FULLY OCCLUDED AND WILL SLOWLY DRIFT
SOUTHEAST ACROSS NORTHERN IOWA THROUGH WEDNESDAY. LIGHT BUT
PERSISTENT SWATH OF RAIN TODAY LOOKS TO BE FORCED BY FGEN ON THE
NORTH SIDE OF TROWAL FEATURE...AND ALSO WITH FGEN ALONG LEADING EDGE
OF COLDER AIR AT H85. THIS FGEN IN THE NAM SHOWS WEAKENS THIS
AFTERNOON WHICH VERIFIES WELL WITH THE AFTERNOON TRENDS OF ECHOES
WEAKENING ON THE MOSAIC REGIONAL RADAR. FGEN FORCING DOES STRENGTHEN
A BIT THIS EVENING ACROSS EAST CENTRAL SOUTH DAKOTA AND INTO PARTS
OF SOUTHWEST MN...SO EXPECT SOME REDEVELOPMENT ACROSS THOSE AREAS
AND WILL GO LIKELY COVERAGE FOR POPS. COLDER AIR IN THE LOW LEVELS
/MAINLY H85 AND BELOW PER FORECAST SOUNDINGS/ WILL ADVECT INTO THE
REGION FROM THE NORTHWEST TONIGHT AND WEDNESDAY. UPSTREAM AIR IS
STILL MOIST HOWEVER SO CLOUDY CONDITIONS WITH LOW CEILINGS ARE
EXPECTED TO PERSIST DESPITE A NORTHWEST WIND. LATE IN THE DAY
WEDNESDAY...SOME SUN MAY BEGIN TO FILTER IN FROM THE W/NW ALONG WITH
SOME WARMER H85 TEMPS ACROSS CENTRAL SD AND HAVE INCREASED HIGH
TEMPS A BIT THERE. NEVERTHELESS...ANOTHER COOL CLOUDY DAY /WITH SCT
SHOWERS MAINLY EAST ACROSS SOUTHWEST MN/ IS EXPECTED FOR TOMORROW.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 302 PM CDT TUE MAY 21 2013

WEDNESDAY NIGHT INTO THURSDAY WILL SEE A RIDGE OF HIGH PRESSURE MOVE
EAST AND SOUTHEAST...SETTING UP JUST EAST OF THE AREA BY THURSDAY
AFTERNOON. THIS SHOULD SET UP A NICE DAY WITH COOL MORNING LOWS IN
THE 40S AND HIGHS IN THE UPPER 60S TO LOWER 70S.

FRIDAY LOOKING WINDY WITH A STRONG SOUTHERLY GRADIENT EXPECTED TO
DEVELOP. THE 925MB WINDS EXPECTED TO BE IN THE 20 TO 30 KNOT RANGE
WHICH SHOULD MIX TO THE SURFACE. CLOUDS WILL BE ON THE INCREASE
THROUGH THE DAY AND WITH INCREASED LAPSE RATES MAINLY WEST OF
INTERSTATE 29 BUT LOW LEVEL INSTABILITY LACKING MAYBE SOME ACCAS
DEVELOPMENT THROUGH THE DAY BUT AT THIS TIME NOT LEANING TOWARDS ANY
WIDE COVERAGE OF ACTIVITY.

THE MAIN FEATURE SATURDAY THROUGH TUESDAY SHOULD BE AN UPPER LEVEL
RIDGE WHICH WILL GRADUALLY BREAK DOWN BY MONDAY NIGHT AS WEST COAST
TROUGH WORKS INTO THE ROCKIES. THE GFS AND GEM ARE A BIT SHARPER
WITH THIS RIDGE THAN THE ECMWF WHICH SUPPORTS WARMER CONDITIONS WITH
850MB TEMPERATURES ABOUT 5 TO 8 DEGREES HIGHER. THE GFS ENSEMBLE
DOES HINT THAT THIS MIGHT BE A BIT OVERDONE BUT IS STILL RUNNING
ABOUT 3-5 DEGREES WARMER THAN THE ECMWF. THE ECMWF ENSEMBLE
SPAGHETTI PLOT DOES INDICATE THAT THE MAJORITY OF THE 850MB
TEMPERATURE MEMBERS ARE WARMER THAN NORMAL DURING THIS TIME FRAME AS
WELL SO AT LEAST THE 0Z ECMWF MAY BE RUNNING A BIT ON THE COOL SIDE.
THUNDERSTORM CHANCES SHOULD EXIST THROUGH MOST OF THE TIME FRAME
WITH SOME DECENT INSTABILITY SUGGESTED THROUGH THE PERIOD. WILL
CONTINUE THE MID RANGE POPS FOR THIS POTENTIAL WITH NO REAL WAY AT
THIS TIME TO PINPOINT ANY PARTICULAR. THE MAIN FOCUS OF INTEREST
WITH THE THUNDERSTORM CHANCES WILL BE THE POTENTIAL FOR A WARM FRONT
TO WORK INTO THE AREA AND STALL OUT WITH CAP BREAKING BECOMING THE
MAIN CHALLENGE THROUGH THE PERIOD. ALSO OF NOTE UPPER LEVEL FLOW
PRETTY WEAK SO THE LOW LEVEL FLOW WILL DICTATE MOTION WHICH IN THIS
CASE WOULD BE MORE OF A SOUTH OR SOUTHEAST DIRECTION...KEEPING MUCH
OF THE ACTIVITY IN FAR SOUTHERN CWA OR JUST SOUTH. THE 0Z ECMWF IS
MUCH MORE STABLE DURING THIS TIME WHILE THE GEM IS MORE IN LINE WITH
THE GFS SO CONFIDENCE FAIRLY LOW WITH MODEL DISAGREEMENT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 1046 PM CDT TUE MAY 21 2013

ONCE AGAIN...MVFR CONDITIONS WILL LIKELY DOMINATE THE WEATHER
FOR THE REST OF TONIGHT AND WEDNESDAY ALONG AND NORTH OF I
90...WITH MVFR TO LOWER END VFR SOUTH OF I 90. ONE CHALLENGE IN
THIS FORECAST IS THAT THERE WILL PROBABLY BE PATCHES OF DRIZZLE
MOVING THROUGH THE AREA TONIGHT AND WEDNESDAY. DRIZZLE WILL LIKELY
LOWER THE CONDITIONS INTO THE IFR CATEGORY FOR BRIEF PERIODS OF
TIME. HOWEVER...DUE TO THE INTERMITTENT AND SPOTTY NATURE OF THE
DRIZZLE...IT IS EXTREMELY DIFFICULT TO PREDICT THESE EPISODES MUCH
AHEAD OF TIME. THEREFORE SHORT TERM AMENDMENTS TO THE TAFS COULD
OCCUR TO ACCOUNT FOR THESE CONDITIONS.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...

000
FXUS63 KFSD 212358
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
658 PM CDT TUE MAY 21 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 302 PM CDT TUE MAY 21 2013

UPPER LOW THAT IS DOMINATING THE WEATHER IN THE SHORT TERM IS
CURRENTLY LOCATED OVER NORTHEAST SOUTH DAKOTA PER LATEST WATER VAPOR
IMAGERY. THIS LOW HAS ALREADY FULLY OCCLUDED AND WILL SLOWLY DRIFT
SOUTHEAST ACROSS NORTHERN IOWA THROUGH WEDNESDAY. LIGHT BUT
PERSISTENT SWATH OF RAIN TODAY LOOKS TO BE FORCED BY FGEN ON THE
NORTH SIDE OF TROWAL FEATURE...AND ALSO WITH FGEN ALONG LEADING EDGE
OF COLDER AIR AT H85. THIS FGEN IN THE NAM SHOWS WEAKENS THIS
AFTERNOON WHICH VERIFIES WELL WITH THE AFTERNOON TRENDS OF ECHOES
WEAKENING ON THE MOSAIC REGIONAL RADAR. FGEN FORCING DOES STRENGTHEN
A BIT THIS EVENING ACROSS EAST CENTRAL SOUTH DAKOTA AND INTO PARTS
OF SOUTHWEST MN...SO EXPECT SOME REDEVELOPMENT ACROSS THOSE AREAS
AND WILL GO LIKELY COVERAGE FOR POPS. COLDER AIR IN THE LOW LEVELS
/MAINLY H85 AND BELOW PER FORECAST SOUNDINGS/ WILL ADVECT INTO THE
REGION FROM THE NORTHWEST TONIGHT AND WEDNESDAY. UPSTREAM AIR IS
STILL MOIST HOWEVER SO CLOUDY CONDITIONS WITH LOW CEILINGS ARE
EXPECTED TO PERSIST DESPITE A NORTHWEST WIND. LATE IN THE DAY
WEDNESDAY...SOME SUN MAY BEGIN TO FILTER IN FROM THE W/NW ALONG WITH
SOME WARMER H85 TEMPS ACROSS CENTRAL SD AND HAVE INCREASED HIGH
TEMPS A BIT THERE. NEVERTHELESS...ANOTHER COOL CLOUDY DAY /WITH SCT
SHOWERS MAINLY EAST ACROSS SOUTHWEST MN/ IS EXPECTED FOR TOMORROW.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 302 PM CDT TUE MAY 21 2013

WEDNESDAY NIGHT INTO THURSDAY WILL SEE A RIDGE OF HIGH PRESSURE MOVE
EAST AND SOUTHEAST...SETTING UP JUST EAST OF THE AREA BY THURSDAY
AFTERNOON. THIS SHOULD SET UP A NICE DAY WITH COOL MORNING LOWS IN
THE 40S AND HIGHS IN THE UPPER 60S TO LOWER 70S.

FRIDAY LOOKING WINDY WITH A STRONG SOUTHERLY GRADIENT EXPECTED TO
DEVELOP. THE 925MB WINDS EXPECTED TO BE IN THE 20 TO 30 KNOT RANGE
WHICH SHOULD MIX TO THE SURFACE. CLOUDS WILL BE ON THE INCREASE
THROUGH THE DAY AND WITH INCREASED LAPSE RATES MAINLY WEST OF
INTERSTATE 29 BUT LOW LEVEL INSTABILITY LACKING MAYBE SOME ACCAS
DEVELOPMENT THROUGH THE DAY BUT AT THIS TIME NOT LEANING TOWARDS ANY
WIDE COVERAGE OF ACTIVITY.

THE MAIN FEATURE SATURDAY THROUGH TUESDAY SHOULD BE AN UPPER LEVEL
RIDGE WHICH WILL GRADUALLY BREAK DOWN BY MONDAY NIGHT AS WEST COAST
TROUGH WORKS INTO THE ROCKIES. THE GFS AND GEM ARE A BIT SHARPER
WITH THIS RIDGE THAN THE ECMWF WHICH SUPPORTS WARMER CONDITIONS WITH
850MB TEMPERATURES ABOUT 5 TO 8 DEGREES HIGHER. THE GFS ENSEMBLE
DOES HINT THAT THIS MIGHT BE A BIT OVERDONE BUT IS STILL RUNNING
ABOUT 3-5 DEGREES WARMER THAN THE ECMWF. THE ECMWF ENSEMBLE
SPAGHETTI PLOT DOES INDICATE THAT THE MAJORITY OF THE 850MB
TEMPERATURE MEMBERS ARE WARMER THAN NORMAL DURING THIS TIME FRAME AS
WELL SO AT LEAST THE 0Z ECMWF MAY BE RUNNING A BIT ON THE COOL SIDE.
THUNDERSTORM CHANCES SHOULD EXIST THROUGH MOST OF THE TIME FRAME
WITH SOME DECENT INSTABILITY SUGGESTED THROUGH THE PERIOD. WILL
CONTINUE THE MID RANGE POPS FOR THIS POTENTIAL WITH NO REAL WAY AT
THIS TIME TO PINPOINT ANY PARTICULAR. THE MAIN FOCUS OF INTEREST
WITH THE THUNDERSTORM CHANCES WILL BE THE POTENTIAL FOR A WARM FRONT
TO WORK INTO THE AREA AND STALL OUT WITH CAP BREAKING BECOMING THE
MAIN CHALLENGE THROUGH THE PERIOD. ALSO OF NOTE UPPER LEVEL FLOW
PRETTY WEAK SO THE LOW LEVEL FLOW WILL DICTATE MOTION WHICH IN THIS
CASE WOULD BE MORE OF A SOUTH OR SOUTHEAST DIRECTION...KEEPING MUCH
OF THE ACTIVITY IN FAR SOUTHERN CWA OR JUST SOUTH. THE 0Z ECMWF IS
MUCH MORE STABLE DURING THIS TIME WHILE THE GEM IS MORE IN LINE WITH
THE GFS SO CONFIDENCE FAIRLY LOW WITH MODEL DISAGREEMENT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 655 PM CDT TUE MAY 21 2013

ONCE AGAIN...MVFR CONDITIONS WILL LIKELY DOMINATE THE WEATHER
TONIGHT AND WEDNESDAY ALONG AND NORTH OF I 90...WITH MVFR TO LOWER
END VFR SOUTH OF I 90. THE ONE WILDCARD IN THIS FORECAST IS THAT
THERE WILL LIKELY BE PATCHES OF DRIZZLE MOVING THROUGH THE AREA
TONIGHT AND WEDNESDAY. DRIZZLE WILL LIKELY LOWER THE CONDITIONS
INTO THE IFR CATEGORY FOR BRIEF PERIODS OF TIME. HOWEVER...DUE TO
THE INTERMITTENT AND SPOTTY NATURE OF THE DRIZZLE...IT IS
EXTREMELY DIFFICULT TO PREDICT THESE EPISODES MUCH AHEAD OF TIME.
THEREFORE EXPECT SHORT TERM AMENDMENTS TO THE TAFS TO ACCOUNT FOR
THESE CONDITIONS.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...

000
FXUS63 KFSD 212003
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
303 PM CDT TUE MAY 21 2013

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 302 PM CDT TUE MAY 21 2013

UPPER LOW THAT IS DOMINATING THE WEATHER IN THE SHORT TERM IS
CURRENTLY LOCATED OVER NORTHEAST SOUTH DAKOTA PER LATEST WATER VAPOR
IMAGERY. THIS LOW HAS ALREADY FULLY OCCLUDED AND WILL SLOWLY DRIFT
SOUTHEAST ACROSS NORTHERN IOWA THROUGH WEDNESDAY. LIGHT BUT
PERSISTENT SWATH OF RAIN TODAY LOOKS TO BE FORCED BY FGEN ON THE
NORTH SIDE OF TROWAL FEATURE...AND ALSO WITH FGEN ALONG LEADING EDGE
OF COLDER AIR AT H85. THIS FGEN IN THE NAM SHOWS WEAKENS THIS
AFTERNOON WHICH VERIFIES WELL WITH THE AFTERNOON TRENDS OF ECHOES
WEAKENING ON THE MOSAIC REGIONAL RADAR. FGEN FORCING DOES STRENGTHEN
A BIT THIS EVENING ACROSS EAST CENTRAL SOUTH DAKOTA AND INTO PARTS
OF SOUTHWEST MN...SO EXPECT SOME REDEVELOPMENT ACROSS THOSE AREAS
AND WILL GO LIKELY COVERAGE FOR POPS. COLDER AIR IN THE LOW LEVELS
/MAINLY H85 AND BELOW PER FORECAST SOUNDINGS/ WILL ADVECT INTO THE
REGION FROM THE NORTHWEST TONIGHT AND WEDNESDAY. UPSTREAM AIR IS
STILL MOIST HOWEVER SO CLOUDY CONDITIONS WITH LOW CEILINGS ARE
EXPECTED TO PERSIST DESPITE A NORTHWEST WIND. LATE IN THE DAY
WEDNESDAY...SOME SUN MAY BEGIN TO FILTER IN FROM THE W/NW ALONG WITH
SOME WARMER H85 TEMPS ACROSS CENTRAL SD AND HAVE INCREASED HIGH
TEMPS A BIT THERE. NEVERTHELESS...ANOTHER COOL CLOUDY DAY /WITH SCT
SHOWERS MAINLY EAST ACROSS SOUTHWEST MN/ IS EXPECTED FOR TOMORROW.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 302 PM CDT TUE MAY 21 2013

WEDNESDAY NIGHT INTO THURSDAY WILL SEE A RIDGE OF HIGH PRESSURE MOVE
EAST AND SOUTHEAST...SETTING UP JUST EAST OF THE AREA BY THURSDAY
AFTERNOON. THIS SHOULD SET UP A NICE DAY WITH COOL MORNING LOWS IN
THE 40S AND HIGHS IN THE UPPER 60S TO LOWER 70S.

FRIDAY LOOKING WINDY WITH A STRONG SOUTHERLY GRADIENT EXPECTED TO
DEVELOP. THE 925MB WINDS EXPECTED TO BE IN THE 20 TO 30 KNOT RANGE
WHICH SHOULD MIX TO THE SURFACE. CLOUDS WILL BE ON THE INCREASE
THROUGH THE DAY AND WITH INCREASED LAPSE RATES MAINLY WEST OF
INTERSTATE 29 BUT LOW LEVEL INSTABILITY LACKING MAYBE SOME ACCAS
DEVELOPMENT THROUGH THE DAY BUT AT THIS TIME NOT LEANING TOWARDS ANY
WIDE COVERAGE OF ACTIVITY.

THE MAIN FEATURE SATURDAY THROUGH TUESDAY SHOULD BE AN UPPER LEVEL
RIDGE WHICH WILL GRADUALLY BREAK DOWN BY MONDAY NIGHT AS WEST COAST
TROUGH WORKS INTO THE ROCKIES. THE GFS AND GEM ARE A BIT SHARPER
WITH THIS RIDGE THAN THE ECMWF WHICH SUPPORTS WARMER CONDITIONS WITH
850MB TEMPERATURES ABOUT 5 TO 8 DEGREES HIGHER. THE GFS ENSEMBLE
DOES HINT THAT THIS MIGHT BE A BIT OVERDONE BUT IS STILL RUNNING
ABOUT 3-5 DEGREES WARMER THAN THE ECMWF. THE ECMWF ENSEMBLE
SPAGHETTI PLOT DOES INDICATE THAT THE MAJORITY OF THE 850MB
TEMPERATURE MEMBERS ARE WARMER THAN NORMAL DURING THIS TIME FRAME AS
WELL SO AT LEAST THE 0Z ECMWF MAY BE RUNNING A BIT ON THE COOL SIDE.
THUNDERSTORM CHANCES SHOULD EXIST THROUGH MOST OF THE TIME FRAME
WITH SOME DECENT INSTABILITY SUGGESTED THROUGH THE PERIOD. WILL
CONTINUE THE MID RANGE POPS FOR THIS POTENTIAL WITH NO REAL WAY AT
THIS TIME TO PINPOINT ANY PARTICULAR. THE MAIN FOCUS OF INTEREST
WITH THE THUNDERSTORM CHANCES WILL BE THE POTENTIAL FOR A WARM FRONT
TO WORK INTO THE AREA AND STALL OUT WITH CAP BREAKING BECOMING THE
MAIN CHALLENGE THROUGH THE PERIOD. ALSO OF NOTE UPPER LEVEL FLOW
PRETTY WEAK SO THE LOW LEVEL FLOW WILL DICTATE MOTION WHICH IN THIS
CASE WOULD BE MORE OF A SOUTH OR SOUTHEAST DIRECTION...KEEPING MUCH
OF THE ACTIVITY IN FAR SOUTHERN CWA OR JUST SOUTH. THE 0Z ECMWF IS
MUCH MORE STABLE DURING THIS TIME WHILE THE GEM IS MORE IN LINE WITH
THE GFS SO CONFIDENCE FAIRLY LOW WITH MODEL DISAGREEMENT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1217 PM CDT TUE MAY 21 2013

THIS EARLY AFTERNOON...WIDESPREAD MVFR WITH A FEW AREAS OF IFR
CIGS PREVAILED ACROSS SOUTHEAST SOUTH DAKOTA...WHILE MORE
OPEN CELL LOW VFR CIGS PREVAILED ACROSS SOUTHWEST MN AND NORTHWEST
IA. LOW PRESSURE /MOVING SLOWLY SOUTHEAST/ CONTINUED TO BRING
PERSISTENT LIGHT RAIN TO THE HON TAF SITE AND OCCASIONAL SHOWERS
TO FSD. MVFR CONDITIONS WILL CONTINUE ACROSS THE HON/FSD SITES
THROUGH THIS EVENING ALONG WITH CONTINUED SHOWERS...THEN EXPECT
IFR CIGS TONIGHT AS MOISTURE SETTLES. SUX WILL SEE SOME
MVFR CIGS ADVECT SOUTHEAST INTO THE AREA THIS AFTERNOON ALONG WITH
SOME ISOLATED SHOWERS...THEN MVFR CONDITIONS ARE EXPECTED TO
CONTINUE TONIGHT. MVFR CIGS ARE EXPECTED TO PREVAIL ACROSS THE
ENTIRE AREA WEDNESDAY AS THE UPPER LOW SLOWLY BEGINS TO EXIT THE
REGION.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...
LONG TERM...08
AVIATION...

000
FXUS63 KFSD 211717
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1217 PM CDT TUE MAY 21 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT TUE MAY 21 2013

UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE AREA WITH BEST LIFT AND
MOISTURE TRANSPORT LOCATED ACROSS THE NORTHERN AND WESTERN PORTIONS
OF THE FORECAST AREA. FURTHER TO THE EAST...INSTABILITY SHOWERS MAY
DEVELOP...BUT WITH LIMITED HEATING AND INSTABILITY...AM NOT REALLY
EXPECTING MUCH IN THE WAY OF THUNDER/SEVERE WEATHER.  WITH A FAIR
AMOUNT OF CLOUD COVER...TEMPERATURES SHOULD REMAIN 10 TO 15 DEGREES
BELOW NORMAL TODAY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 408 AM CDT TUE MAY 21 2013

UPPER LEVEL LOW WILL CONTINUE TO SLOWLY WOBBLE SOUTHEASTWARD TONIGHT
AND WEDNESDAY...WITH ITS CENTER TRACKING ACROSS OUR EASTERN FORECAST
AREA TONIGHT AND INTO SOUTHEASTERN IOWA ON WEDNESDAY. UNSETTLED
CONDITIONS WILL PERSIST TONIGHT AS THE TROWAL CONTINUES TO SHIFT
EAST THROUGH THE FORECAST AREA. BEST POTENTIAL FOR SHOWERS WILL BE
ACROSS OUR NORTHERN FORECAST AREA TONIGHT WHILE MUCH OF NORTHWEST
IOWA WILL LIKELY REMAIN IN THE DRY SECTOR THROUGH THE BULK OF THE
NIGHT AND WILL SEE MORE ISOLATED SHOWERS. WITH THE LOW FILLING AND
MOVING AWAY FROM THE REGION ON WEDNESDAY...SCATTERED SHOWERS CAN BE
EXPECTED ACROSS THE CWA IN THE MORNING THEN TAPERING OFF FROM WEST
TO EAST IN THE AFTERNOON AND EVENING. SHOWERS ARE EXPECTED TO REMAIN
GENERALLY ON THE LIGHT WITH MOST LOCATIONS SEEING LESS THAN A
QUARTER INCH OF ADDITIONAL RAINFALL. PERSISTENT CLOUDY SKIES AND
MOIST CONDITIONS WILL LEAD TO ANOTHER COOL DAY ON WEDNESDAY WITH
HIGHS ONLY EXPECTED TO REACH THE UPPER 50S AND LOWER 60S.

SURFACE HIGH PRESSURE SINKS SOUTHWARD ON WEDNESDAY NIGHT WHICH
SHOULD FINALLY ALLOW THE CLOUDS TO BEGIN SCOURING OUT
OVERNIGHT...HOWEVER LOWS WILL BE UNSEASONABLY COOL IN THE LOW TO MID
40S. WHILE LATE WEEK INTO EARLY NEXT WEEK LOOKS TO RESUME THE WET
PATTERN...TEMPERATURES WILL ALSO BE ON A GRADUAL WARMING TREND.
SOUTHWESTERLY UPPER LEVEL FLOW WILL DIRECT SEVERAL SHORTWAVES
THROUGH THE REGION AND BRING THE POTENTIAL FOR SCATTERED
THUNDERSTORMS EACH PERIOD. TIMING THESE WAVES REMAINS
PROBLEMATIC...HOWEVER ALL MODELS DO POINT TO A VERY ACTIVE PATTERN
DURING THIS TIME WITH SEVERAL WAVES OF PRECIPITATION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1217 PM CDT TUE MAY 21 2013

THIS EARLY AFTERNOON...WIDESPREAD MVFR WITH A FEW AREAS OF IFR
CIGS PREVAILED ACROSS SOUTHEAST SOUTH DAKOTA...WHILE MORE
OPEN CELL LOW VFR CIGS PREVAILED ACROSS SOUTHWEST MN AND NORTHWEST
IA. LOW PRESSURE /MOVING SLOWLY SOUTHEAST/ CONTINUED TO BRING
PERSISTENT LIGHT RAIN TO THE HON TAF SITE AND OCCASIONAL SHOWERS
TO FSD. MVFR CONDITIONS WILL CONTINUE ACROSS THE HON/FSD SITES
THROUGH THIS EVENING ALONG WITH CONTINUED SHOWERS...THEN EXPECT
IFR CIGS TONIGHT AS MOISTURE SETTLES. SUX WILL SEE SOME
MVFR CIGS ADVECT SOUTHEAST INTO THE AREA THIS AFTERNOON ALONG WITH
SOME ISOLATED SHOWERS...THEN MVFR CONDITIONS ARE EXPECTED TO
CONTINUE TONIGHT. MVFR CIGS ARE EXPECTED TO PREVAIL ACROSS THE
ENTIRE AREA WEDNESDAY AS THE UPPER LOW SLOWLY BEGINS TO EXIT THE
REGION.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM.../
LONG TERM...
AVIATION...

000
FXUS63 KFSD 211128
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
628 AM CDT TUE MAY 21 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT TUE MAY 21 2013

UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE AREA WITH BEST LIFT AND
MOISTURE TRANSPORT LOCATED ACROSS THE NORTHERN AND WESTERN PORTIONS
OF THE FORECAST AREA. FURTHER TO THE EAST...INSTABILITY SHOWERS MAY
DEVELOP...BUT WITH LIMITED HEATING AND INSTABILITY...AM NOT REALLY
EXPECTING MUCH IN THE WAY OF THUNDER/SEVERE WEATHER.  WITH A FAIR
AMOUNT OF CLOUD COVER...TEMPERATURES SHOULD REMAIN 10 TO 15 DEGREES
BELOW NORMAL TODAY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 408 AM CDT TUE MAY 21 2013

UPPER LEVEL LOW WILL CONTINUE TO SLOWLY WOBBLE SOUTHEASTWARD TONIGHT
AND WEDNESDAY...WITH ITS CENTER TRACKING ACROSS OUR EASTERN FORECAST
AREA TONIGHT AND INTO SOUTHEASTERN IOWA ON WEDNESDAY. UNSETTLED
CONDITIONS WILL PERSIST TONIGHT AS THE TROWAL CONTINUES TO SHIFT
EAST THROUGH THE FORECAST AREA. BEST POTENTIAL FOR SHOWERS WILL BE
ACROSS OUR NORTHERN FORECAST AREA TONIGHT WHILE MUCH OF NORTHWEST
IOWA WILL LIKELY REMAIN IN THE DRY SECTOR THROUGH THE BULK OF THE
NIGHT AND WILL SEE MORE ISOLATED SHOWERS. WITH THE LOW FILLING AND
MOVING AWAY FROM THE REGION ON WEDNESDAY...SCATTERED SHOWERS CAN BE
EXPECTED ACROSS THE CWA IN THE MORNING THEN TAPERING OFF FROM WEST
TO EAST IN THE AFTERNOON AND EVENING. SHOWERS ARE EXPECTED TO REMAIN
GENERALLY ON THE LIGHT WITH MOST LOCATIONS SEEING LESS THAN A
QUARTER INCH OF ADDITIONAL RAINFALL. PERSISTENT CLOUDY SKIES AND
MOIST CONDITIONS WILL LEAD TO ANOTHER COOL DAY ON WEDNESDAY WITH
HIGHS ONLY EXPECTED TO REACH THE UPPER 50S AND LOWER 60S.

SURFACE HIGH PRESSURE SINKS SOUTHWARD ON WEDNESDAY NIGHT WHICH
SHOULD FINALLY ALLOW THE CLOUDS TO BEGIN SCOURING OUT
OVERNIGHT...HOWEVER LOWS WILL BE UNSEASONABLY COOL IN THE LOW TO MID
40S. WHILE LATE WEEK INTO EARLY NEXT WEEK LOOKS TO RESUME THE WET
PATTERN...TEMPERATURES WILL ALSO BE ON A GRADUAL WARMING TREND.
SOUTHWESTERLY UPPER LEVEL FLOW WILL DIRECT SEVERAL SHORTWAVES
THROUGH THE REGION AND BRING THE POTENTIAL FOR SCATTERED
THUNDERSTORMS EACH PERIOD. TIMING THESE WAVES REMAINS
PROBLEMATIC...HOWEVER ALL MODELS DO POINT TO A VERY ACTIVE PATTERN
DURING THIS TIME WITH SEVERAL WAVES OF PRECIPITATION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE MAY 21 2013

LARGE UPPER LOW WILL BE DRIFTING SOUTHWARD ACROSS THE NORTHERN
PLAINS TODAY INTO TONIGHT GREATLY AFFECTING THE SIOUX FALLS FORECAST
AREA. IN GENERAL...IT APPEARS MAINLY VFR CONDITIONS WILL PREVAIL
SOUTH OF I 90...WITH A LOT OF MVFR TO EVEN A BIT OF IFR NORTH OF I
90. RAIN WILL BE WRAPPING DOWN BEHIND THE LOW... AFFECTING AREAS
WEST OF I 29 LATE TONIGHT AND TUESDAY MORNING... THEN MOVING
EASTWARD ALONG I 29 LATE TUESDAY AFTERNOON AND EVENING. IN AREAS
OF RAIN...MVFR VISIBILITIES ARE CERTAINLY POSSIBLE WITH EVEN SOME
LOCALIZED IFR AT TIMES. THERE IS ALSO A POSSIBILITY BASED ON THE
LATEST NAM MODEL THAT MVFR COULD MOVE INTO KSUX TUESDAY
EVENING...THOUGH CONFIDENCE IS LOW ENOUGH AT THIS POINT THAT IT
WAS NOT INCLUDED IN THE FORECAST.
&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM.../
LONG TERM...
AVIATION...

000
FXUS63 KFSD 210911
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
411 AM CDT TUE MAY 21 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT TUE MAY 21 2013

UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE AREA WITH BEST LIFT AND
MOISTURE TRANSPORT LOCATED ACROSS THE NORTHERN AND WESTERN PORTIONS
OF THE FORECAST AREA. FURTHER TO THE EAST...INSTABILITY SHOWERS MAY
DEVELOP...BUT WITH LIMITED HEATING AND INSTABILITY...AM NOT REALLY
EXPECTING MUCH IN THE WAY OF THUNDER/SEVERE WEATHER.  WITH A FAIR
AMOUNT OF CLOUD COVER...TEMPERATURES SHOULD REMAIN 10 TO 15 DEGREES
BELOW NORMAL TODAY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 408 AM CDT TUE MAY 21 2013

UPPER LEVEL LOW WILL CONTINUE TO SLOWLY WOBBLE SOUTHEASTWARD TONIGHT
AND WEDNESDAY...WITH ITS CENTER TRACKING ACROSS OUR EASTERN FORECAST
AREA TONIGHT AND INTO SOUTHEASTERN IOWA ON WEDNESDAY. UNSETTLED
CONDITIONS WILL PERSIST TONIGHT AS THE TROWAL CONTINUES TO SHIFT
EAST THROUGH THE FORECAST AREA. BEST POTENTIAL FOR SHOWERS WILL BE
ACROSS OUR NORTHERN FORECAST AREA TONIGHT WHILE MUCH OF NORTHWEST
IOWA WILL LIKELY REMAIN IN THE DRY SECTOR THROUGH THE BULK OF THE
NIGHT AND WILL SEE MORE ISOLATED SHOWERS. WITH THE LOW FILLING AND
MOVING AWAY FROM THE REGION ON WEDNESDAY...SCATTERED SHOWERS CAN BE
EXPECTED ACROSS THE CWA IN THE MORNING THEN TAPERING OFF FROM WEST
TO EAST IN THE AFTERNOON AND EVENING. SHOWERS ARE EXPECTED TO REMAIN
GENERALLY ON THE LIGHT WITH MOST LOCATIONS SEEING LESS THAN A
QUARTER INCH OF ADDITIONAL RAINFALL. PERSISTENT CLOUDY SKIES AND
MOIST CONDITIONS WILL LEAD TO ANOTHER COOL DAY ON WEDNESDAY WITH
HIGHS ONLY EXPECTED TO REACH THE UPPER 50S AND LOWER 60S.

SURFACE HIGH PRESSURE SINKS SOUTHWARD ON WEDNESDAY NIGHT WHICH
SHOULD FINALLY ALLOW THE CLOUDS TO BEGIN SCOURING OUT
OVERNIGHT...HOWEVER LOWS WILL BE UNSEASONABLY COOL IN THE LOW TO MID
40S. WHILE LATE WEEK INTO EARLY NEXT WEEK LOOKS TO RESUME THE WET
PATTERN...TEMPERATURES WILL ALSO BE ON A GRADUAL WARMING TREND.
SOUTHWESTERLY UPPER LEVEL FLOW WILL DIRECT SEVERAL SHORTWAVES
THROUGH THE REGION AND BRING THE POTENTIAL FOR SCATTERED
THUNDERSTORMS EACH PERIOD. TIMING THESE WAVES REMAINS
PROBLEMATIC...HOWEVER ALL MODELS DO POINT TO A VERY ACTIVE PATTERN
DURING THIS TIME WITH SEVERAL WAVES OF PRECIPITATION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1054 PM CDT MON MAY 20 2013

LARGE UPPER LOW WILL BE DRIFTING SOUTHWARD ACROSS THE NORTHERN
PLAINS TONIGHT AND TUESDAY...GREATLY AFFECTING THE SIOUX FALLS
FORECAST AREA. IN GENERAL...IT APPEARS MAINLY VFR CONDITIONS WILL
PREVAIL SOUTH OF I 90...WITH A LOT OF MVFR TO EVEN A BIT OF IFR
NORTH OF I 90. RAIN WILL BE WRAPPING DOWN BEHIND THE LOW...
AFFECTING AREAS WEST OF I 29 LATE TONIGHT AND TUESDAY MORNING...
THEN MOVING EASTWARD ALONG I 29 LATE TUESDAY AFTERNOON AND
EVENING. IN AREAS OF RAIN...MVFR VISIBILITIES ARE CERTAINLY
POSSIBLE WITH EVEN SOME LOCALIZED IFR AT TIMES. THERE IS ALSO A
POSSIBILITY BASED ON THE LATEST NAM MODEL THAT MVFR COULD MOVE
INTO KSUX LATE TUESDAY AND THIS WILL BE WATCHED.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM.../
LONG TERM...
AVIATION...

000
FXUS63 KFSD 210355
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1055 PM CDT MON MAY 20 2013

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 353 PM CDT MON MAY 20 2013

UPPER LEVEL LOW SPINNING AROUND WITH THE BEST MOISTURE DELIVERY TO
THE NORTH OF THE CWA. THE AFFECTS OF SOME OF THIS WILL WRAP INTO
WESTERN PARTS OF THE CWA TONIGHT AND CONTINUE INTO TUESDAY. A FEW
INSTABILITY SHOWERS WILL REMAIN POSSIBLE OVER THE REMAINDER OF THE
CWA BUT WITH CAPE VALUES MAINLY 250 J/KG OR LESS AND SHEAR MINIMAL
NOT EXPECTING ANY THING OTHER THAN SHOWERS AND ISOLATED
THUNDERSTORMS. A FEW OF THE THUNDERSTORMS COULD PRODUCE BRIEFLY
GUSTY WINDS AND SMALL HAIL BUT NOT SEVERE. THE MOST ORGANIZED AREA
WILL BE WITH THE TROWAL LIKE FEATURE TO THE NORTH AND EAST OVER
WESTERN ARTS IF THE CWA WHILE AREAS IN THE SOUTHERN CWA WILL SEE THE
LOW WOBBLE EAST THIS EVENING WITH A POTENTIAL BAND OF SHOWERS AND
ISOLATED THUNDERSTORMS DEVELOPING IN FAR SOUTHERN SD INTO NORTHWEST
IOWA.

UNDER CLOUDY CONDITIONS AND A CONTINUED WEST WIND OVERNIGHT
TEMPERATURES SHOULD NOT DROP SIGNIFICANTLY...SO EXPECTING LOWS FROM
ABOUT 50 TO 55...COOLEST IN CENTRAL SD. COOL AIR WILL REMAIN IN
PLACE ON TUESDAY AN LOCAL FORECAST SOUNDINGS NOT VERY SUPPORTIVE ON
SUNSHINE SO EVEN IF THE CLOUDS CAN DISSIPATE A BIT ANY WARMING WILL
JUST INDUCE ADDITIONAL CUMULUS DEVELOPMENT. THUS TEMPERATURES WILL
NOT GO FAR AND SUSPECT MOST LOCATIONS WILL ONLY REACH THE MID 50S TO
LOWER 60S FOR HIGHS AS THIS IS ABOUT THE TEMPERATURES THAT WE WOULD
GET CUMULUS REDEVELOPMENT AND HALT ANY WARMING.


.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 353 PM CDT MON MAY 20 2013

SCATTERED SHOWERS WILL REMAIN APPROPRIATE FOR TUESDAY NIGHT INTO
WEDNESDAY AS THE UPPER LEVEL LOW MAKES A SLOW EASTWARD PROGRESSION
THROUGH THE PERIOD. COOLEST THERMAL PROFILES WILL BE LOCATED ACROSS
THE AREA ON TUESDAY NIGHT...WITH LOWS DROPPING DOWN INTO MID AND
UPPER 40S. ONLY SUBTLE WARMING ON WEDNESDAY WITH SHOWERS TAPERING
OFF FROM WEST TO EAST DURING THE DAY...AND HIGHS UPPER 50S TO LOWER
60S.

THE UPPER LEVEL LOW FINALLY PUSHES OFF INTO THE GREAT LAKES/OHIO
VALLEY REGION ON THURSDAY...AS SURFACE HIGH PRESSURE BUILDS
SOUTHWARD THROUGH THE PLAINS STATES. THIS WILL RESULT IN A DRY
DAY...AND WITH THE SUN FINALLY BREAKING OUT WILL HAVE SOME
WARMING...TEMPERED SOMEWHAT BY A EAST/NORTHEASTERLY LOW LEVEL FLOW
AND AFTERNOON HIGHS IN THE MID AND UPPER 60S. MOST OF FRIDAY LOOKS
TO BE DRY IN A TRANSITIONING SOUTHERLY LOW LEVEL FLOW AS THE HIGH
PRESSURE MOVES EAST. EVEN WITH WARMING THERMAL PROFILES HIGHS WILL
BE SIMILAR TO THURSDAY WITH CLOUDS INCREASING DURING THE
DAY...TOPPING OUT IN THE UPPER 60S TO AROUND 70.

UNSETTLED CONDITIONS RETURN FOR LATER ON FRIDAY AND THROUGH THE
WEEKEND WITH A CHANCE OF CONVECTION EACH DAY AS A SERIES OF
SHORTWAVES TRACK THROUGH THE UPPER LEVEL RIDGE PARKED OVER THE
REGION. DOES LOOK TO BE A SLOW WARMING TREND DURING THE
PERIOD...ALBEIT AROUND NORMAL FOR THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1054 PM CDT MON MAY 20 2013

LARGE UPPER LOW WILL BE DRIFTING SOUTHWARD ACROSS THE NORTHERN
PLAINS TONIGHT AND TUESDAY...GREATLY AFFECTING THE SIOUX FALLS
FORECAST AREA. IN GENERAL...IT APPEARS MAINLY VFR CONDITIONS WILL
PREVAIL SOUTH OF I 90...WITH A LOT OF MVFR TO EVEN A BIT OF IFR
NORTH OF I 90. RAIN WILL BE WRAPPING DOWN BEHIND THE LOW...
AFFECTING AREAS WEST OF I 29 LATE TONIGHT AND TUESDAY MORNING...
THEN MOVING EASTWARD ALONG I 29 LATE TUESDAY AFTERNOON AND
EVENING. IN AREAS OF RAIN...MVFR VISIBILITIES ARE CERTAINLY
POSSIBLE WITH EVEN SOME LOCALIZED IFR AT TIMES. THERE IS ALSO A
POSSIBILITY BASED ON THE LATEST NAM MODEL THAT MVFR COULD MOVE
INTO KSUX LATE TUESDAY AND THIS WILL BE WATCHED.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...08
LONG TERM...JM
AVIATION...