Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 201739
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1239 PM CDT SUN JUL 20 2014

.UPDATE...
ISSUED AT 1224 PM CDT SUN JUL 20 2014

UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 243 AM CDT SUN JUL 20 2014

HIGH TEMPERATURES ARE FORECAST TO TAKE A JUMP UPWARD TODAY AS MUCH
WARMER SOUTHWEST LOW LEVEL AIR FINALLY MOVES IN. OVER THE PAST FEW
DAYS H85 TEMPERATURES HAVE BEEN IN A 12-16 DEG C RANGE FROM EAST
TO WEST RESPECTIVELY ACROSS THE FA. BY THIS AFTERNOON...H85
TEMPERATURES ARE PROGGED TO RISE INTO THE 18-24 DEG C RANGE FROM
EAST TO WEST. MIX-DOWN INDICATES HIGHS REACHING INTO THE LOWER 90S
ACROSS WEST CENTRAL MN WITH MIDDLE TO UPPER 80S IN THE METRO WITH
LOWER TO MIDDLE 80S ACROSS WEST CENTRAL WI. DEW POINTS WILL ALSO
BE ON THE RISE TODAY...ESPECIALLY ACROSS WESTERN MN WHERE LOWER TO
MIDDLE 70S ARE FORECAST BY LATE AFTERNOON. THIS RESULTS IN AN
APPARENT TEMPERATURE NEAR 100 DEGREES FOR AN HOUR OUR TWO IN LAC
QUI PARLE AND YELLOW MEDICINE COUNTIES. WILL NOT ISSUE A HEAT
ADVISORY DUE TO THE LIMITED TIME. MONDAY WILL BE A MUCH DIFFERENT
SITUATION WITH HEAT RELATED PRODUCTS NOW IN EFFECT.

ANOTHER CONCERN FOR LATE TODAY AND TONIGHT IS THE THREAT FOR
THUNDERSTORMS. A FRONTAL BOUNDARY ACROSS THE WESTERN DAKOTAS THIS
MORNING WILL PUSH INTO NW MINNESOTA BY THIS EVENING. ALL OF THE
WRF SOLUTIONS POINT TO SCATTERED THUNDERSTORMS DEVELOPING AHEAD
OF THE FRONT LATE IN THE AFTERNOON FROM NEAR KPIR TO KINL. THE
MPX...ARW AND NMM WRF/S BRUSH WEST CENTRAL INTO CENTRAL MN WITH A
FEW STORMS DURING THE EVENING WITH NO ACTIVITY SURVIVING AFTER
MIDNIGHT. THE EXCEPTION IS THE SPC WRF. IT PROGRESSES ACTIVITY
EAST SOUTHEAST ALL NIGHT LONG WITH STORMS REACH NORTHERN IA BY
DAYBREAK MONDAY. FOLLOWED THE CONSENSUS AND ALLOWED FOR STORMS TO
MAKE THEIR WAY INTO CENTRAL MN DURING THE EVENING WITH AN
EXTENSION DOWN ACROSS THE WEST METRO TO NEAR KRWF. A FEW SEVERE
STORMS ARE POSSIBLE IN THE FAR NW CWA (KAXN) IN THE EARLY EVENING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 243 AM CDT SUN JUL 20 2014

THE FOCUS ON THE LONG TERM IS SQUARELY ON THE HEAT MONDAY FOLLOWED
BY A HIGH PROBABILITY OF A SEVERE MCS MONDAY NIGHT. AT THE
BEGINNING OF THE PERIOD...THERMAL RIDGING WILL BE FOUND ALONG AN
AXIS EXTENDING FROM THE PLAINS NORTHEAST INTO WEST CENTRAL AND
NORTHEAST MINNESOTA. THIS WILL SLOWLY SAG SOUTH THROUGH THE DAY
REACHING THE NORTHERN MPX CWA BY AFTERNOON. 925 MB TEMPS OF +26 TO
+28C FAVOR HIGHS IN THE LOW TO MID 90S. OF MORE SIGNIFICANCE IS
THE OPPRESSIVE HUMIDITY THAT WILL BUILD DURING THE DAY AS A SLUG
OF DEEP MOISTURE ARRIVES. MODELS HAVE BEEN CONSISTENT FOR SEVERAL
DAYS NOW THAT DEW POINTS COULD REACH THE MID TO POSSIBLY UPPER 70S
BY LATE MONDAY AFTERNOON. MET AND MAV MOS EVEN ADVERTISE 82 TO 83
DEGREE DEW POINTS IN MADISON MN. THERE IS VERY HIGH CONFIDENCE
HEAT INDICES WILL EXCEED 100 ACROSS MN COUNTIES AND FAR WESTERN
MN...SO WENT AHEAD AND POSTED A HEAT ADVISORY FOR THOSE LOCATIONS
AND AN EXCESSIVE HEAT WARNING FOR THE MSP METRO. HEAT INDICES
COULD APPROACH 110 DEGREES IN WEST CENTRAL MN IF DEW POINTS DO IN
FACT APPROACH 80 DEGREES TOWARD EVENING.

ON MONDAY EVENING...MID LEVEL LAPSE RATES WILL STEEPEN AS A WAVE
RIDING ALONG THE NORTHERN PERIPHERY OF THE RIDGE APPROACHES. THE
7.5-8.5 C/KM LAPSE RATES WILL OVERSPREAD THE HOT AND VERY MOIST
BOUNDARY LAYER AND LEAD TO AN EXTREMELY UNSTABLE AIRMASS WITH
MLCAPE OF 4000 TO 5000 J/KG. RAPID THUNDERSTORM DEVELOPMENT WILL
OCCUR ACROSS THE DAKOTAS DURING THE AFTERNOON AND QUICKLY ACQUIRE
A COLD POOL AS THE ACTIVITY RACES EASTWARD AROUND 50 KT. A WELL
ORGANIZED MCS CAPABLE OF WIDESPREAD WIND DAMAGE WILL PUSH ACROSS
THE MN COUNTIES MONDAY EVENING AND REACH WESTERN WI BY THE EARLY
OVERNIGHT HOURS. GIVEN THE FORWARD PROPAGATION MOTION AND DCAPE
VALUES BETWEEN 600 AND 1000 J/KG...DECIDED TO INCLUDE SEVERE IN
THE GRIDS WITH A RELATIVELY HIGH CONFIDENCE FOR WIND DAMAGE. SPC
SWO DAY 2 MAKES MENTION OF A POSSIBLE MDT RISK IN LATER OUTLOOKS
AND I CANNOT DISAGREE. IF THE BOUNDARY LAYER REMAINS SOMEWHAT
MIXED DURING THE EVENING...DCAPE COULD IMPROVE TO ABOVE 1000 J/KG
AND THE THREAT FOR A DERECHO WOULD INCREASE GIVEN THE EXTREME
INSTABILITY IN PLACE...DEW POINTS IN THE MID 70S...AND RAPID MCS
MOTION.

COLD FRONT WILL SAG SLOWLY SOUTH TUESDAY MORNING. DEW POINTS WILL
BE SLOW TO DROP THROUGH THE DAY...WHICH MAY ALLOW FOR SOME
THUNDERSTORM REDEVELOPMENT ACROSS SRN MN. WIDESPREAD CLOUD COVER
SHOULD HAMPER TEMPS...BUT WILL NEED TO WATCH DEW POINTS SINCE THEY
WILL GOVERN THE NEED FOR ANOTHER HEAT ADVISORY.

A MUCH COOLER AND DRIER AIRMASS WILL ACCOMPANY CANADIAN HIGH
PRESSURE MIDWEEK BEFORE STORM CHANCES INCREASE AGAIN LATE WEEK
WITH THE ARRIVAL OF ANOTHER WRAPPED UP SYSTEM OVER THE SOUTHERN
CANADIAN ROCKIES. THIS SYSTEM APPEARS TO KEEP THINGS QUITE
UNSETTLED INTO NEXT WEEKEND AND MAY EVENTUALLY DROP ANOTHER CUT
OFF LOW INTO THE UPPER MIDWEST IN THE FAR EXTENDED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1224 PM CDT SUN JUL 20 2014

WARM FRONT WILL CONTINUE TO LIFT NE THRU THE REGION TDA...WITH A
TIGHT PRES GRADIENT ON ITS LEADING EDGE PLUS DEEP MIXING PRODUCING
BREEZY/GUSTY WINDS THRU THIS EVE. WINDS SETTLE DOWN TO THE 5-10 KT
RANGE TMRW THEN PICK UP AGAIN AFTER DAYBREAK TMRW TO 8-12 KT WITH
OCNL HIGHER GUSTS. MID- AND UPR-LVL CLOUDS WILL PREVAIL THROUGHOUT
THIS TAF PERIOD...WITH THE MIDLVL CLOUDS DISSIPATING OVERNIGHT.
ONLY SHOT AT PRECIP LOOKS TO BE KAXN WHICH WILL BE IN CLOSEST
PROXIMITY TO AN UPR LVL SHORTWAVE MOVG THRU. TIMING LOOKS TO BE
MID-TO-LATE EVENING FOR ANY CONVECTION. NO OTHER TAF SITES HAVE
PRECIP AS ANY PRECIP LOOKS TO DISSIPATE BEFORE DRIVING ANY FURTHER
SE. THE STRONG LOW LEVEL INFLUX OF MOISTURE WITH ENOUGH DECOUPLING
OVERNIGHT WILL CREATE AREAS OF MVFR FOG ACRS MUCH OF S-CENTRAL MN
INTO WRN WI TONIGHT. ONCE THIS DISSIPATES SHORTLY AFTER
DAYBREAK...VSBY RESTRICTIONS MAY WELL TAKE THE FORM OF HAZE.
ATTM...HAVE ONLY INDICATED 6SM BUT IT IS VERY POSSIBLE MUCH OF THE
DAY COULD HOLD IN THE 4-5SM VSBY RANGE DUE TO HAZE.

KMSP...NO PRECIP CONCERNS THRU TMRW AFTN AND NO CEILING ISSUES
EXPECTED. MAIN CONCERNS WILL BE PRE-DAWN AND DAYBREAK MVFR VSBY
ARND THE TIME OF THE MORNING PUSH...THEN HAZE FOR MUCH OF THE DAY.
WILL ADVERTISE 6SM HZ BUT VSBY COULD BE LOWER FROM TIME TO TIME
DURG THE DAY TMRW WITH THE HIGH DEWPOINTS IN PLACE.


/OUTLOOK FOR KMSP/
MON...VFR. WINDS S 10-15KTS.
MON NIGHT...MAINLY VFR. STRONG TSTMS LIKELY WITH OCNL PERIODS OF
MVFR/IFR. WINDS S 10KTS...HIGHER IN TSTMS.
TUE...VFR WITH IFR/TSRA POSSIBLE IN THE MORNING. WINDS SW 10 KTS
BECOMING NW.
WED...VFR. WINDS NE 10KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...HEAT ADVISORY FROM 11 AM TO 9 PM CDT MONDAY FOR MNZ041>045-
     047>059-064>067-073>078-082>085-091>093.

     EXCESSIVE HEAT WARNING FROM 11 AM TO 9 PM CDT MONDAY FOR
     MNZ060>063-068>070.

WI...HEAT ADVISORY FROM 11 AM TO 9 PM CDT MONDAY FOR WIZ014-023-024.

&&

$$

UPDATE...JPC
SHORT TERM...RAH
LONG TERM...BORGHOFF
AVIATION...JPC






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