Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 250406 AAC
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1106 PM CDT THU JUL 24 2014

.UPDATE...
ISSUED AT 804 PM CDT THU JUL 24 2014

ONLY UNTIL RECENTLY HAVE MODELS BEGUN TO LATCH ONTO THE CURRENT
SITUATION. HRRR AND NOW HOPWRF HAVE BEGUN TO CONVERGE TOWARD A
SOLUTION WHICH ALLOWS CONVECTION OVER THE WESTERN DAKOTAS AND
EASTERN MONTANA TO EXPAND EASTWARD RAPIDLY DURING THE LATE EVENING
AND SPILL INTO MINNESOTA OVERNIGHT. THE GLOBAL MODELS THROUGH 18Z
DID NOT HANDLE THIS IDEA WELL...SO WHILE CONFIDENCE HAS BEEN QUITE
LOW IT IS STARTING TO INCREASE. IT REMAINS TO BE SEEN WHETHER THE
00Z GLOBAL MODELS WILL LATCH ONTO THIS SOLUTION...BUT GIVEN THE
RECENT TRENDS IN THE CAMS THERE IS A PRETTY GOOD CHANCE.

STRONG MOISTURE ADVECTION OVER EASTERN SOUTH DAKOTA/NEBRASKA WHERE
PW VALUES ARE 1.5 TO 1.9 INCHES WILL CONTINUE TO IMPROVE OVERNIGHT
AS A 40 TO 50 KT LLJ DEVELOPS. THIS LLJ WILL THEN VEER EASTWARD INTO
SWRN MN OVERNIGHT AND FOCUS THIS MOISTURE TRANSPORT OVER THE MPX
CWA. A STRONGLY TO EXTREMELY UNSTABLE AIRMASS TO THE WEST SHOULD
MAINTAIN THIS DEVELOPING MCS AS IT CONTINUES EAST FOR THE NEXT 12
HOURS. THUS...THE SOLUTION KEEPING ACTIVITY CONFINED TO IOWA /A
LA NAM...GFS...AND CMC/ IS LOOKING LESS AND LESS LIKELY. INCREASED
POPS ACROSS CENTRAL MN INTO THE LIKELY RANGE AND THE TIMING WAS
BASED ON THE LATEST HRRR/HOPWRF.

ANY SEVERE THREAT WILL BE DETERMINED BY HOW FAR EAST THE EML AND
ASSOCIATED INSTABILITY CAN PROGRESS. BEST CHANCE FOR ANY SEVERE
WOULD BE ACROSS WRN MN...CLOSEST TO THE EML. LARGE HAIL WOULD BE
THE PRIMARY CONCERN.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 233 PM CDT THU JUL 24 2014

SHORT TERM CONCERNS REMAIN COVERAGE OF THUNDER OVERNIGHT INTO
FRIDAY.  ALSO...CHANCE OF LARGE HAIL MAINLY LATER TONIGHT INTO SOUTH
CENTRAL MN WITH SOME SEVERE POTENTIAL LINGERING INTO FRIDAY AHEAD OF
FRONT.

UPPER RIDGE IS BEGINNING TO MOVE EAST WITH ONE IMPULSE DROPPING
SOUTHEAST OVER WESTERN MINNESOTA AND THE NEXT WAVE LIFTING INTO
NORTHWEST NODAK AND SOUTHERN MANITOBA. IT APPEARS THE INITIAL WAVE
WILL DROP SOUTHEAST THIS EVENING ALONG THE EASTERN PERIPHERY OF THE
INSTABILITY GRADIENT TO THE WEST AND THE EDGE OF LOW LEVEL WAA/STEEP
MID LEVEL LAPSE RATES. MODELS DIVERGE ON DEVELOPMENT THEREAFTER...
WITH SEVERAL HIRES MODELS INDICATING CANADIAN SYSTEM TAKES OVER AND
DROPS SOUTHEAST OVERNIGHT.  STILL SOME POTENTIAL OF LLJ DRIVING
CONVECTION INTO MAINLY SOUTH CENTRAL MN LATE.  WILL CARRY HIGHER
POPS TO THE SOUTH ONCE AGAIN...IN SPIRIT WITH THE PREVIOUS
FORECAST.  SHOULD SEE SOME QPF MOVE THROUGH THE MOST OF AREA.

FRIDAY STILL SEE SOME POTENTIAL OF ISOLATED/WIDELY SCATTERED
CONVECTION DEVELOPING ALONG THE FRONT AS IT MOVES ACROSS THE EASTERN
PORTION OF THE AREA INTO THE AFTERNOON.  WILL HOLD ONTO SOME LOW END
POPS FOR THIS POTENTIAL.  INSTABILITY ALONG THE FRONT DOES INCREASE
DURING THE DAY BUT LOW LEVEL CONVERGENCE REMAINS WEAK.  MUCH OF THE
HIGH END FORCING IS DRIVEN EAST DURING THE MORNING AS WELL.
TEMPERATURES SHOULD WARM INTO THE MID 80S TO THE SOUTHWEST WITH MIX
WITH THE WEAK FRONT AND UPPER 70S/LOWER 80S ELSEWHERE.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 233 PM CDT THU JUL 24 2014

MAIN CONCERN IN THE EXTENDED PERIOD IS WHETHER SHRA/TSRA DEVELOP
FURTHER SOUTHWARD ACROSS MN THAN EXPECTED FOR LATE SAT AFTN/EARLY
SUNDAY AS A STRONG...AND UNUSUAL UPPER LOW FOR THIS TIME OF YEAR
MOVES EAST-SE ACROSS THE NORTHERN PLAINS...AND INTO THE WESTERN
GREAT LAKES BY SUNDAY. WILL FOLLOW PREVIOUS FORECAST WITH THE MAIN
AREA OF SHRA ACROSS CENTRAL MN/EC MN AND WC WI WHERE BOTH UPPER
LEVEL ENERGY AND HIGHER RH FIELDS ARE EVIDENT. K-INDEX AND 85H
SHOWALTER INDEX FIELDS INDICATED MAINLY SHRA WITH SOME EMBEDDED
TSRA FOR THE TYPICAL DIURNAL TIME FRAME. SUNDAY MORNING/AFTN WILL
LIKELY BE BREEZY AS THE SFC LOW DEEPENS AS IT MOVES SE ACROSS THE
WESTERN GREAT LAKES IN RESPONSE TO THE UPPER JET.

NO CHGS IN THE EXTENDED PERIOD BEYOND THIS WEEKEND WITH BOTH THE
EC/GFS ADVERTISING A STRONG UPPER RIDGE BUILDING OFF THE EAST
COAST OF NORTH AMERICA WITH A DEEPENING LONG WAVE TROUGH ACROSS
THE EASTERN 1/3 OF THE CONUS. THIS WILL KEEP OUR REGION COOLER
THAN NORMAL AND MAINLY DRY. ALTHOUGH COOLER TEMPS ARE
EXPECTED...STANDARD ANOMALIES ARE NOT TOO IMPRESSIVE COMPARED TO
THE DEEP SE U.S. WHERE ANOMALIES COULD DROP TO 2-3 BLW NORMAL.
FOR COMPARISON...OUR REGION WILL BE SLIGHTLY COOLER...BUT STILL
NICE FOR LATE JULY/EARLY AUGUST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1059 PM CDT THU JUL 24 2014

CONFIDENCE HAS INCREASED QUITE A BIT IN THE LAST FEW HOURS WITH
REGARD TO THE PRECIPITATION EVOLUTION OVERNIGHT INTO EARLY FRIDAY
MORNING. EXPECT TO SEE SHOWERS AND THUNDERSTORMS RAPIDLY DEVELOP
AROUND 07Z ACROSS SOUTHWESTERN MN AND EXPAND EASTWARD IN THE HOURS
FOLLOWING...REACHING STC AROUND 09Z...MSP AROUND 10Z...AND RNH BY
11Z. SOME THUNDER MAY ACCOMPANY THIS PRECIP...ESPECIALLY ACROSS
SOUTHERN AND WESTERN MN. ANY SHOWER/STORM ACTIVITY SHOULD DIMINISH
2 TO 4 HOURS AFTER IT BEGINS. FOLLOWING THE PRECIP...MODELS INSIST
ON DEVELOPING IFR OR MVFR CIGS. NOT CONFIDENT IN THIS SCENARIO AS
THEY HAVE OVERDONE THESE EVENTS TIME AND TIME AGAIN THIS SUMMER.
WILL CONTINUE THE SCT MENTION AROUND 2 KFT BEFORE CIGS RISE TOWARD
4 KFT BY AFTERNOON.

KMSP...CURRENT PROJECTIONS INDICATE PRECIP WILL ARRIVE AT MSP
AROUND 10Z AND PERSIST THROUGH ABOUT 12 OR 13Z. CONFIDENCE HAS
INCREASED AND BROUGHT BACK THE PREVAILING GROUP FOR THIS
TIMEFRAME.

/OUTLOOK FOR KMSP/
SAT...VFR. WINDS WSW AT 5-10KTS.
SUN...VFR. CHANCE SHRA/MVFR CIGS. WINDS NW AT 10-15 KTS.
MON...VFR. WINDS N 5 KT.

&&

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

$$

UPDATE...BORGHOFF
SHORT TERM...DWE
LONG TERM...JLT
AVIATION...BORGHOFF






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