000
FXUS63 KFSD 122331
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
630 PM CDT WED MAR 12 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 346 PM CDT WED MAR 12 2014

LOW CLOUDS WILL CONTINUE TO BE A PROBLEM AS THEY ARE ERODED BY
HEATING THE REST OF THE AFTERNOON...BUT WITH THE PROSPECT OF SOME
REDEVELOPMENT EAST OF FSD...ESPECIALLY NORTHEAST...TONIGHT. THIS
SEEMS REASONABLE GIVEN THAT THE CURRENT EROSION IS EAST OF THE
WARM FRONT. WILL KEEP LOW CLOUDS IN THE EAST FOR PART OF TONIGHT
BUT THE DETAILS WILL NEED WATCHING. MEANWHILE...SOME MIDDLE CLOUDS
WILL SPREAD RAPIDLY OVER THE AREA FROM THE NORTHWEST...BUT DO NOT
EXPECT THEM TO BE SOLID. LATER TONIGHT DRYING BEHIND THE WARM
FRONT SHOULD CLEAR THE LOW CLOUDS OUT. LOW TEMPERATURES WILL BE A
BIT TRICKY ESPECIALLY FAR EAST WHERE ANY CLEARING WILL ALLOW A
GREATER DROP...BUT EVENTUALLY THE MILD REGIME WEST OF THE WARM
FRONT WILL LIMIT THE COOLING. MID 20S EAST TO LOWER 30S WEST LOOKS
GOOD FOR LOWS.

THURSDAY LOOKS PRETTY DRY AT ALL LEVELS AND IT WILL SIMPLY BE A WARM
DAY WITH A MODERATE SOUTHWESTERLY BREEZE. GUIDANCE IS NOT WARM
ENOUGH AND THE MID 50S TO MID 60S WE HAVE BEEN CARRYING FOR MOST OF
THE AREA LOOKS GOOD. DRYING FAR SOUTHWEST MAY ELEVATE THE FIRE
DANGER SOME THERE THURSDAY AFTERNOON...BUT NOT TOO CLOSE TO RED FLAG
STATUS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 346 PM CDT WED MAR 12 2014

THURSDAY NIGHT IS HIGHLIGHTED BY A STRONG SHORT WAVE MOVING ACROSS
THE AREA...BUT WITH QG FORCING SHOWING MUCH OF THE DYNAMICS
REMAINING WELL NORTHEAST OF OUR FORECAST AREA. THE LOW AND MID
LEVEL FRONTOGENESIS IS PRETTY STRONG AS COLDER AIR RUSHES IN...BUT
HUMIDITY TIME SECTIONS AND SOUNDINGS SHOW A REAL DRY AIR MASS
BELOW ABOUT 650MB. THEREFORE NOT EXPECTING ANYTHING MORE THAN JUST
SOME PASSING MID AND HIGH CLOUDS. WITH NORTHWEST WINDS STAYING
MIXED THROUGH THE NIGHT...LOWS SHOULD HOLD IN A WIDESPREAD 30 TO
35 DEGREE RANGE.

FRIDAY LOOKS STILL LOOKS LIKE A MILD DAY WITH BRISK MIXING
NORTHWEST WINDS. WILL HAVE TO MONITOR THIS DAY FOR ANY FIRE
WEATHER POTENTIAL IN OUR SOUTH AND SOUTHWEST ZONES...BUT FOR NOW
THE MINIMUM HUMIDITY VALUES LOOK TOO HIGH TO WARRANT ANY FIRE
WEATHER WATCHES...COUPLED WITH WIND VALUES NOT QUITE STRONG ENOUGH
IN THE AFTERNOON.

THE NAM IS KIND OF OFF ON ITS OWN FRIDAY NIGHT AND SATURDAY...SO
PREFERRED TO FOLLOW THE GFS AND ECMWF SOLUTIONS. COOL AIR
CONTINUES TO OOZE SLOWLY IN FROM THE NORTH WHERE HIGH PRESSURE OF
AT LEAST 1035MB IS SITUATED IN SOUTH CENTRAL CANADA BY 00Z SUNDAY.
THIS SCENARIO WILL GIVE CHILLY HIGHS FOR OUR EASTERN ZONES...WITH
MILDER READINGS HEADING THROUGHOUT OUR SOUTHERN AND SOUTHWEST
ZONES WITH A VERY SHARP THERMAL GRADIENT SETTING UP JUST SOUTH OF
I 90. THIS SAID...IF THE 925MB TEMPERATURES PAN OUT CLOSER THEN
THE ECMWF...THEN WE WILL NEED TO COOL OFF HIGHS FURTHER IN FUTURE
RUNS. SO STAY TUNED. WITH THE AMOUNT OF SNOW COVER WHICH STILL
RESIDES NORTHEAST OF OUR FORECAST AREA...WOULD NOT BE SURPRISED AT
ALL IF THIS IS THE CASE IF WE HAVE TO KNOCK SATURDAYS HIGHS BACK A
GOOD 5 TO 10 DEGREES IN FUTURE FORECASTS.

IN THE EXTENDED PORTION OF THE FORECAST...SATURDAY NIGHT THROUGH
WEDNESDAY...NOT AT ALL CONFIDENT WITH MANY OF THE DETAILS OF
VIRTUALLY ANY WEATHER PARAMETER. LARGE SCALE UPPER RIDGING IS
NOTED ON SUNDAY THROUGHOUT THE WESTERN HALF OF THE UNITED
STATES...WHICH WILL LIKELY WARM TEMPERATURES A FAIR AMOUNT FROM
THE SUNDAY THROUGH MONDAY TIME FRAME. BUT BEGINNING ON MONDAY...
THE LARGE SCALE FLOW REGIME RADICALLY DIFFERS BETWEEN THE VARIOUS
DETERMINISTIC MODELS...WITH THEIR RESPECTIVE ENSEMBLE MEANS
FOLLOWING SUIT. SO DIFFERENT ARE THE RESPECTIVE MODELS IT MAKES IT
DIFFICULT TO EVEN USE A SUPER ENSEMBLE MEAN. TO MAKE MATTERS WORSE...
THE GFS AND ECMWF HAVE MORE OR LESS LOCKED ONTO A SPECIFIC REGIME
EARLY NEXT WEEK THE PAST COUPLE OF RUNS WITH THEIR RESPECTIVE
SOLUTIONS. IN GENERAL...THE ECMWF DRIVES STRONG SHORT WAVE ENERGY
DOWN THE NORTHWEST FLOW ALOFT RIGHT ACROSS THIS AREA. BY TUESDAY...
WITH STRONG LOW PRESSURE TO THE SOUTH...THIS SOLUTION WRAPS A
COLD LOW LAYER CONVEYOR BELT IN FROM THE EAST AND ACTUALLY
PRODUCES A PRETTY DECENT SNOW FOR MUCH OF OUR FORECAST AREA. THE
GFS KEEPS THE UPPER FLOW PRETTY FLAT...NOT DOING THIS AT ALL...AND
THUS KEEPS THINGS RATHER MILD AND DRY. NOT TO BE OUT DONE...THE
GEM GLOBAL BY 12Z TUESDAY IS ALSO OFF ON ITS OWN...SHOWING A
PRETTY SHARP NORTHWEST FLOW ALOFT BUT NO SHORT WAVE ENERGY. THIS
WOULD GIVE AN IN BETWEEN SOLUTION. AT 12Z TUESDAY...THE UKMET IS
ALSO IN ITS OWN WORLD...SHOWING MORE OF ZONAL FLOW LIKE THE
GFS...BUT WITH SHORT WAVE ENERGY MOVING INTO THE WESTERN PLAINS.

SO AGAIN...THE MODELS ARE ALL OVER THE MAP FOR EARLY TO MID WEEK
NEXT WEEK. FOR NOW...KEEPING CONTINUITY WITH THE PREVIOUS FORECAST
IS PRUDENT. THIS KEEPS TEMPERATURES MONDAY THROUGH WEDNESDAY ON
THE MILD SIDE...BUT NOT TOO MUCH ABOVE NORMALS...COUPLED WITH WEAK
CHANCES FOR OFF AND ON PRECIP. EVEN ON SUNDAY...NOT TOO CONFIDENT
ABOUT A WARM AIR ADVECTION BAND OF LIGHT PRECIPITATION MOVING FROM
WEST TO EAST ACROSS OUR FORECAST AREA...IF THE RESPECTIVE MODELS
ARE CORRECT IN KEEPING THE ATMOSPHERE DRY BELOW ABOUT 750MB. BUT IF
IN THE DAYS TO COME THE ECMWF BEGINS TO PAN OUT CLOSEST TO
REALITY...THERE WILL HAVE TO BE SOME SERIOUS ALTERATIONS COMPLETED
TO TUESDAYS FORECAST. BUT AM NOT GOING OUT ON A LIMB THAT FAR OUT YET.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 630 PM CDT WED MAR 12 2014

MVFR STRATUS DECK PERSIST NEAR/EAST OF A LINE FROM KMML-KSPW AT THE
START OF THE PERIOD. MODELS POINTING AT EXPANSION OF THIS BACK TO
THE WEST THROUGH 12Z...BEFORE QUICKLY ERODING THROUGH MORNING HOURS
THURSDAY. ANY MVFR CONDITIONS EXPECTED TO REMAIN EAST OF TAF SITES
AT THIS TIME SO WILL CARRY NO MENTION OF CLOUDS IN 1-3KFT RANGE IN
THIS FORECAST. WILL SEE AREA OF MID LEVEL CLOUDS ABOVE 6KFT AFFECT
THE TAF LOCATIONS THOUGH...WITH MORE EXTENSIVE CLEARING EXPECTED
AFTER 10Z-12Z. LINGERING NORTHWEST WIND GUSTS OF 20-25KT WEST OF THE
JAMES RIVER VALLEY SHOULD DIMINISH WITH LOSS OF HEATING EARLY THIS
EVENING. WIND BECOMING WEST TO SOUTHWEST LATE TONIGHT/THURSDAY WITH
A FEW GUSTS 20-30KT AGAIN POSSIBLE IN THE AFTERNOON...MAINLY IN THE
HIGHER ELEVATIONS OF THE BUFFALO RIDGE IN SOUTHWEST MN...AS WELL AS
AREAS WEST OF THE JAMES RIVER AGAIN.

&&

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

$$

SHORT TERM...
LONG TERM...MJ
AVIATION...JH