Area Forecast Discussion
Issued by NWS Twin Cities, MN

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KMPX 140455 AAB
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1155 PM CDT SAT SEP 13 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 327 PM CDT SAT SEP 13 2014

NOT MUCH TO SPEAK OF IN THE SHORT TERM AS WE WILL SEE A COUPLE OF
SHORTWAVES TRAVERSE THE INTERNATIONAL BORDER AS THEY ROTATE AROUND
THE BASE OF THE MEAN CANADIAN TROUGH THAT MORE OR LESS STRETCHES
FROM THE CANADIAN ROCKIES OVER TO ERN QUEBEC. ONLY SIGNIFICANT
CHANGE MADE TO THE GOING FORECAST WAS TO GO SUB-MENTIONABLE ON POPS
TONIGHT THROUGH SUNDAY.

WAA ASSOCIATED WITH THE FIRST WAVE THAT IS MOVING INTO NW MN HAS
RESULTED IN THE ASSORTMENT OF LAYERED CLOUD COVER WE SEE ACROSS MN
THIS AFTERNOON. WAVE 2...WHICH IS THE STRONGER OF THE TWO...IS
APPROACHING NW NODAK. AT THE SFC...WAVE 2 HAS A SFC LOW
APPROACHING WINNIPEG...WITH A TRAILING SFC TROUGH EXTENDING SOUTH
THROUGH THE CENTRAL DAKOTAS. THIS SFC TROUGH WILL WORK ACROSS MN
TONIGHT AND WI SUN MORNING...BUT IT WILL BE LACKING MOISTURE. CAM
REFLECTIVITY FORECASTS SHOW A FEW RETURNS WORKING ACROSS THE
NORTHERN MPX AREA WITH THE TROUGH...BUT NONE OF THE DETERMINISTIC
MODELS PRODUCE QPF...AS THAT IS ALL CONFINED TO NRN MN OUT AHEAD
OF THE PATH OF THE PV ANOMALY. THIS MEANS WE WILL LIKELY JUST SEE
A LOT OF VIRGA... THOUGH DID LEAVE AN OCCASIONAL SPRINKLE WORDING
IN THE FORECAST ALONG THE NRN TIER OF COUNTIES IN THE MPX CWA.

SW WINDS WILL REMAIN ELEVATED THROUGH THE NIGHT...WHICH WILL HELP
KEEP LOWS UP IN THE 40S. BESIDE ELIMINATING THE FROST POTENTIAL
TONIGHT...THE COMBINATION OF THE WINDS AND CLOUDS WITH THE SFC
THROUGH WILL KEEP THE FOG AT BAY AS WELL. IN THE WAKE OF THE TROUGH
FOR SUNDAY...WE WILL GET A PAC AIRMASS THAT WILL HAVE HAD SOME
COMPRESSIONAL WARMING IMPACT IT...WITH 925-850 TEMPS A FEW DEGS
WARMER THAN WHAT WE ARE SEEING TODAY. WITH EXPECTED MIXING TO AROUND
H8 AGAIN...WILL SEE HIGHS PUSH 70 ALONG THE I-90 CORRIDOR...WITH THE
COLD SPOT BEING UP AROUND AXN. THERE THEY WILL GET INTO THE BIT OF
COOLER AIR HEADING ACROSS NRN MN BEHIND THE TROUGH...WITH HIGHS
REMAINING IN THE UPPER 50S AS A RESULT.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 327 PM CDT SAT SEP 13 2014

WE/LL SEE THE LARGE SCALE PATTERN EVOLVE QUITE A BIT THROUGH THE
REMAINDER OF THE FORECAST PERIOD... LEAVING THE QUESTION ONCE
AGAIN AS TO HOW QUICKLY IT WILL SHIFT BACK TO WHERE IT HAS
SEEMINGLY WANTED TO BE FOR SO LONG. OVERALL WE/LL SEE THE
CENTRAL/EASTERN NORTH AMERICAN TROUGH SHIFT EASTWARD TO THE
EASTERN PART OF THE CONTINENT BY MIDWEEK AS RIDGING MOVES INTO THE
WESTERN HALF OF THE COUNTRY AND A SOMEWHAT CUTOFF TROUGH PUSHES
DOWN OFF THE WEST COAST. BY THE END OF THE WEEK THE FLOW BECOMES
ZONAL WITH THE MAIN JET WEST TO EAST NEAR THE INTERNATIONAL
BORDER. AFTER THAT THINGS BECOME SOMEWHAT MORE MUDDY IN THE
DETERMINISTIC AND ENSEMBLE SOLUTIONS. BY THE END OF NEXT WEEKEND
THE ECMWF HAS A BROAD UPPER RIDGE FROM THE WEST COAST TO THE GREAT
LAKES. THE GFS SOMEWHAT MIMICS THIS... BUT SHOWS A CUTOFF LOW OVER
THE MISSISSIPPI VALLEY. THEY WIND UP WITH THOSE DIFFERENCES DUE TO
SOME DIFFERENT HANDLING WITH THE SHORTWAVE AND ASSOCIATED SURFACE
FEATURES THAT WILL IMPACT OUR AREA AT THE END OF THE WEEK. THE GFS
ACTUALLY SLOWED THE OVERALL PROGRESSION OF THINGS DOWN AND IS
SOMEWHAT SIMILAR TO THE 00Z ECMWF... WHILE THE ECMWF BECAME MORE
PROGRESSIVE. IN THE END... THEY/RE SIMILAR IN TERMS OF THE
SENSIBLE WEATHER FOR OUR AREA... WITH TIMING BEING THE PRIMARY
DIFFERENCE. GIVEN THE COINCIDENT SPREAD APPARENT IN THE ENSEMBLE
GUIDANCE... WILL NEED TO BLANKET POPS OVER A PERIOD THAT CAPTURES
A BIT OF THE SLOWER AND FASTER POTENTIAL... LEADING TO POPS MOST
LIKELY OCCUPYING MORE TIME THAN WILL ULTIMATELY OCCUR.

LATE SUNDAY NIGHT INTO MONDAY WILL SEE AN AREA OF PCPN SKIRT BY
NEAR THE IOWA BORDER AHEAD OF THE UPPER TROUGH IN AN AREA OF
DECENT MID-LEVEL FRONTOGENESIS AND UPPER DIVERGENCE. KEPT POPS IN
ACROSS THE SOUTH SIMILAR TO THE PREVIOUS FORECAST... ALTHOUGH
WOULD EXPECT A SHARP CUTOFF ON THE NORTH SIDE GIVEN THE DRY
ANTECEDENT AIRMASS. AFTER THAT WE/LL SEE THE SURFACE RIDGE DRIFT
ACROSS THE AREA THROUGH WEDNESDAY... WITH DRY CONDITIONS AND A
SLOW WARMING TREND. BY THURSDAY WE START TO GET INTO THE PERIOD
WHERE THERE IS MORE SPREAD IN THE MODEL GUIDANCE AS RETURN FLOW
BEGINS TO SETUP AND WE SEE A SURFACE TROUGH BEGIN TO TAKE SHAPE
OVER THE HIGH PLAINS. A COMPROMISE/CONSENSUS SOLUTION LEADS TO THE
INCLUSION OF POPS MOVING ACROSS THE AREA FROM LATE THURSDAY NIGHT
THROUGH THE BALANCE OF THE FORECAST DUE TO THE DIFFERENCES IN
POTENTIAL TIMING AND POSSIBILITY /IF THE GFS PANS OUT/ THAT WE/LL
SEE A CUTOFF LOW DEVELOP.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1151 PM CDT SAT SEP 13 2014

VFR CONDITIONS. SCATTERED-BROKEN MID LEVEL CLOUDS WILL CONTINUE
THROUGH THE PERIOD. SOUTH WINDS WILL VEER WESTERLY LATE SUNDAY
MORNING.

KMSP...NO ADDITIONAL CONCERNS.

/OUTLOOK FOR KMSP/
MON...VFR. WINDS NW AT 10G15 KTS.
TUE...VFR. WINDS SW AT 10 KTS.
WED...VFR. WINDS SE AT 5 KTS.

&&

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

$$

SHORT TERM...MPG
LONG TERM...
AVIATION...BORGHOFF





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.