Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 221105
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
605 AM CDT TUE APR 22 2014

.UPDATE...
ISSUED AT 557 AM CDT TUE APR 22 2014

UPDATED TO INCLUDE 12Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT TUE APR 22 2014

THINGS WILL BE FAIRLY QUIET THROUGH THE SHORT TERM... WITH THE
ONLY ITEM OF ANY CONCERN BEING CHANCES FOR SOME WARM ADVECTION
PCPN TO MOVE INTO THE WESTERN HALF OF THE AREA LATE TONIGHT.
CURRENT SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED NEAR THE
MINNESOTA/DAKOTAS BORDER. THIS FEATURE WILL MOVE EAST THROUGH THE
DAY TODAY AS NORTHWEST UPPER FLOW PERSISTS... KEEPING THINGS
MOSTLY SUNNY AND DRY... ALTHOUGH MID-HIGH CLOUDS WILL START TO
WORK IN FROM THE WEST DURING THE AFTERNOON. THE UPPER TROUGH
CURRENTLY MOVING INTO THE WEST COAST WILL CONTINUE TO PUSH EAST
THROUGH TONIGHT... WORKING TO DRIVE THE UPPER RIDGE AXIS INTO OUR
AREA BY 12Z WEDNESDAY.MID-LEVEL WARM ADVECTION WILL QUICKLY
INCREASE LATE TONIGHT IN RESPONSE TO THE PROGRESSION OF THE UPPER
RIDGE... WITH SUFFICIENT SATURATION LIKELY TO OCCUR OVER THE WEST
AFTER THE 06-09Z FOR SOME PCPN. AT THIS POINT... THINK ANY PCPN
WILL STAY WEST OF I-35 THROUGH 12Z. WOULD BE A BIT MORE CONCERNED
ABOUT PCPN DEVELOPING FARTHER EAST THAN PROGGED BY THE MODELS...
SINCE THAT OFTEN OCCURS IN SIMILAR WARM ADVECTION SCENARIOS... BUT
THE LACK OF ANY APPARENT ELEVATED INSTABILITY THROUGH THE NIGHT
SHOULD KEEP THAT FROM OCCURRING. NEITHER MUCAPE... BEST LI...
SHOWALTER INDICES... NOR SIMPLE CONVECTIVE INSTABILITY VIA
850-500MB DIFFERENTIAL THETA-E INDICATE ANY INSTABILITY WORKING
INTO THE AREA TONIGHT... SO TIMING OF PCPN SHOULD REALLY REMAIN
TIED TO THE ISENTROPIC ASCENT AND SATURATION... WHICH LOOKS TO
ONLY IMPACT THE WESTERN THIRD-TO HALF OF THE AREA OVERNIGHT.
INCLUDED A CHANCE FOR SHRA OVER THE FAR WEST BY 06... THEN BROUGHT
IT TO JUST WEST OF I-35 BY 12Z. WE WILL SEE 850MB TEMPERATURES
WARM SLIGHTLY DURING THE DAY TODAY... AND FORECAST SOUNDINGS
SUGGEST WE SHOULD BE ABLE TO MIX THROUGH AROUND 825MB OR SO...
WHICH SHOULD ALLOW FOR HIGHS OF 60-65 OUT WEST... NEAR 60 IN THE
TWIN CITIES METRO... AND MID 50S IN WEST CENTRAL WISCONSIN.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 335 AM CDT TUE APR 22 2014

LONG TERM CONCERNS IS THE OVERALL DEVELOPMENT AND MOVEMENT OF THE
WESTERN CONUS TROUGH WEDNESDAY AND THURSDAY. IT APPEARS THERE IS A
GOOD LIKELIHOOD OF OF AT LEAST ONE HALF TO 1 INCH OF RAIN ACROSS
MUCH OF THE CENTRAL AND EASTERN PORTION OF THE CWA WEDNESDAY AND
THURSDAY. MUCH COOLER FOR THE REST OF THE PERIOD WITH A SMALL
THREAT OF RAIN AND SNOW CLIPPING MAINLY THE SOUTHERN CWA LATE IN
THE PERIOD.

MODELS ARE IN FAIR AGREEMENT IN THE TIMING AND MOVEMENT OF THE
TROUGH AND SURFACE FRONT DURING THE WED/THU TIME FRAME. LOOKS LIKE
SOME SOWERS DEVELOPING LATER TUESDAY NIGHT AND SPREADING EAST
DURING THE DAY ON WEDNESDAY. WILL RETAIN THE LIKELY POPS...WEST
EARLY...SPREADING INTO WESTERN WISCONSIN IN THE AFTERNOON. THERE
WILL LIKELY BE A LULL IN THE OVERALL ACTIVITY WEDNESDAY AFTERNOON.
THE STRONGER FORCING AND MOISTURE LIFT NORTHEAST ACROSS THE AREA
WEDNESDAY AND THURSDAY. THIS REMAINS THE BEST PERIOD TO CONTINUE
THE CATEGORICAL POPS OVER THE AREA. ABUNDANT CLOUD COVER ALONG
WITH THE RAIN WILL KEEP TEMPERATURES ON THE COOL SIDE OVER MUCH OF
THE AREA...STRUGGLING TO WARM TO 50 IN THE NORTHEAST CWA.
INSTABILITY IS MEAGER ACROSS THE AREA DURING THE PERIOD. THE STRONG
NATURE OF THE TROUGH COULD STILL INITIATE ISOLATED THUNDER OVER THE
AREA DURING THIS PERIOD.

IN THE WAKE OF THE SYSTEM...MUCH COLDER AIR IS DRIVEN SOUTH ACROSS
THE AREA. THE 00Z ECMWF IS EVEN COOLER THAN THE GFS THIS GO ROUND.
THE ECMWF ACTUALLY DRIVES BELOW ZERO H85 TEMPERATUREA OVER THE
NORTHEAST CWA...WITH THE POSSIBILITY OF RAIN/SNOW SCENARIO THERE
THURSDAY AFTERNOON INTO FRIDAY. WILL HAVE TO MONITOR THIS TREND
LATER TODAY.

FOR THE REMAINDER OF THE LONGER TERM...BELOW NORMAL TEMPERATURES
WILL REMAIN THROUGH THE WEEKEND INTO EARLY NEXT WEEK. MODELS ARE
INDICATING THE NEXT TROUGH COMING ASHORE OVER THE WEST COAST LATE
IN THE WEEK. BELIEVE THE 00Z GFS MAY BE A BIT FAST IN DRIVING THE
TROUGH EAST OVER THE WEEKEND. WILL KEEP SATURDAY DRY...AND SPREAD
SOME CHANCE POPS OVER MAINLY THE SOUTHWEST THIRD OF THE CWA INTO
SUNDAY. IT WILL BE TOUGH FOR THE TROUGH TO OVERCOME THE LARGE
CANADIAN HIGH THAT WILL PROVIDE A GENERALLY DRY EASTERLY FLOW
ACROSS THE AREA THROUGH MOST OF TH WEEKEND. ANY PRECIPITATION THAT
DOES MAKE IT INTO THE SOUTH WILL LIKELY BE MIXED RAIN/SNOW COMBO.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 557 AM CDT TUE APR 22 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD AS HIGH
PRESSURE DRIFTS EAST ACROSS THE REGION. WINDS WILL BE LIGHT
THROUGH THE FORECAST... BUT WILL VEER FROM NORTHWEST TO SOUTHEAST
OVER TIME FOR MOST LOCATIONS. MID-HIGH CLOUDS WILL INCREASE FROM
WEST TO EAST THIS AFTERNOON INTO TONIGHT AS THE UPPER RIDGE AXIS
SHIFTS INTO THE AREA. RETURN FLOW ON THE WEST SIDE OF THE
DEPARTING SURFACE HIGH WILL EVENTUALLY BRING ENOUGH MOISTURE AND
FORCING INTO THE AREA FOR SOME PCPN... BUT AT THIS POINT IT LOOKS
LIKE IT WILL HOLD OFF UNTIL JUST AFTER 12Z... SO NO NEED TO
MENTION ANYTHING EXCEPT FOR KMSP WHERE A VCSH SHOULD BE SUFFICIENT
FROM AROUND 15Z ONWARD WEDNESDAY.

KMSP...TAF REFLECTS OVERALL EXPECTATIONS WITH NO SIGNIFICANT
CONCERNS WITH RESPECT TO UNCERTAINTY AND FORECAST CONFIDENCE. WIND
SHIFTS THROUGH THE DAY AND EVENING COULD VARY BY +/- 2 HOURS FROM
FORECAST... BUT SPEEDS WILL GENERALLY BE AOB 10 KT. THERE IS SOME
UNCERTAINTY ON WHEN PCPN MIGHT ARRIVE ON WEDNESDAY... BUT WITH IT
NOT LOOKING TO HAPPEN UNTIL WITHIN 3-6 HOURS OF THE END OF THE
FORECAST CHOSE TO JUST INCLUDE A VCSH AT THIS POINT.

/OUTLOOK FOR KMSP/
WEDNESDAY AFTERNOON...VFR. MVFR CEILINGS AND VISIBILITIES POSSIBLE
WITH A CHANCE OF RAIN. SOUTHEAST WIND 10 TO 20 KT.
WEDNESDAY NIGHT...MVFR CEILINGS AND VISIBILITIES EXPECTED WITH
RAIN... IFR POSSIBLE. SOUTHEAST WIND 10 TO 20 KT.
THURSDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE EARLY.
SOUTHEAST WIND 5 TO 15 KT SHIFTING NORTHWEST.
THURSDAY NIGHT...VFR. NORTHWEST WIND 5 TO 10 KT.
FRIDAY...VFR. NORTHWEST WIND 5 TO 10 KT INCREASING TO 10 TO 15 KT.
FRIDAY NIGHT...VFR. NORTH WIND 5 TO 15 KT BECOMING NORTHEAST.
SATURDAY...VFR. NORTHEAST WIND 5 TO 10 KT.

&&

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

$$

UPDATE...
SHORT TERM...
LONG TERM...DWE
AVIATION...






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