Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 051755
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1155 AM CST THU MAR 5 2015

.SHORT TERM /TODAY/...
ISSUED AT 334 AM CST THU MAR 5 2015

A SHORTWAVE IS PUSHING ACROSS THE STATE AND WILL BE THROUGH IOWA BY
15Z.  WEAK QG FORCING AND ENOUGH LOW LEVEL MOISTURE PRODUCED A BAND
OF LIGHT SNOW OR FLURRIES.  OVERNIGHT...FLURRIES PERSISTED ACROSS
THE FAR SOUTHEAST PORTION OF THE FORECAST AREA BUT DIMINISHED AROUND
3 AM.  VERY COLD TEMPS IN PLACE...ESPECIALLY NORTHEAST WHERE WE
STILL HAVE SEVERAL INCHES OF SNOW COVER.  WIND CHILL VALUES OVER A
SMALL PORTION OF THE FORECAST AREA HAVE FALLEN INTO ADVISORY
CRITERIA BUT GIVEN TO SMALL AERIAL COVERAGE AND DIMINISHING WINDS I
WILL HANDLE THE WIND CHILL ISSUE WITH A SPECIAL WEATHER STATEMENT
VERSUS AN ADVISORY.

TODAY WE WILL SEE A GENERAL NORTHWEST FLOW ALOFT WITH A SURFACE HIGH
PRESSURE SYSTEM SHIFTING ACROSS THE STATE.  WE WILL BE IN A WEST TO
NORTHWEST FLOW THROUGH THE MAJORITY OF THE DAY WITH WINDS FINALLY
SWITCHING AROUND TO THE SOUTHWEST LATE IN THE DAY...AFTER 20Z OR SO.
SOUNDINGS SHOW SOME RESIDUAL LOW LEVEL MOISTURE INTO THE EARLY TO
MID MORNING HOURS BUT ARE VERY DRY ALOFT. I AM NOT REALLY LOOKING
FOR MUCH IN THE WAY OF CLOUD COVER TODAY ALTHOUGH AN APPROACHING
SHORT WAVE LATE IN THE PERIOD WITH A RETURN FLOW SETTING UP AND WEAK
WARM ADVECTION TRYING TO NOSE IN I WOULD NOT BE SURPRISED TO SEE
SOME INCREASE IN MID/HIGH LEVEL CLOUDS LATE IN THE AFTERNOON.

TEMPS WILL BE COOL ONCE AGAIN TODAY AS WINDS DON`T REALLY COME
AROUND TO THE SOUTH UNTIL AFTER 21Z AND THEY WILL BE ON THE LIGHTER
SIDE THROUGH THE AFTERNOON...GENERALLY AROUND 10 MPH OR SO.

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 334 AM CST THU MAR 5 2015

TRANSITIONAL PERIOD IS FORTHCOMING WITH GRADUAL MODERATION INTO
NEXT WEEK AS BROAD NORTHWEST FLOW BECOMES MORE ZONAL BY END OF
FORECAST PERIOD. STRONG WARM ADVECTION IS EXPECTED TONIGHT INTO
FRIDAY AND WILL LIKELY SEE LOWS THIS EVENING BEFORE INCREASING
SOUTH WINDS OVERNIGHT LEAD TO STEADY/SLOWING RISING TEMPERATURES
OVERNIGHT. THE WARMUP WILL PERSIST INTO FRIDAY AS THERMAL RIDGE
BUILDS TOWARD THE STATE. THE FIRST IN A SERIES OF SHORTWAVES
DROPPING SOUTHEAST FROM CANADA WILL ENTER THE REGION ON FRIDAY
NIGHT. WHILE THE BULK OF FORCING AND LIFT WILL REMAIN TO THE
NORTHEAST ALONG WITH THE PRECIPITATION THREAT...A WEAK COLD FRONT
IS EXPECTED TO PASS INTO IOWA PUTTING THE BREAKS ON THE WARMUP.

ANOTHER SHORTWAVE WILL DROP SOUTHEAST LATE SATURDAY NIGHT INTO
SUNDAY. FORCING WILL BE A BIT FARTHER SOUTHWEST WITH THIS SYSTEM
AND MAY BE SUFFICIENT FOR SOME LIGHT SNOW OVERNIGHT SATURDAY NIGHT
INTO SUNDAY MORNING IN NORTHERN IOWA. TEMPERATURES WILL BE
FLAT-LINED THROUGH THE WEEKEND BUT BEGIN RISING WITH AUTHORITY ON
MONDAY INTO TUESDAY AS WEST TO SOUTHWEST FLOW DEVELOPS BRINGING
MILD CONTINENTAL AIR FROM THE SOUTHWEST INTO THE CENTRAL US. THIS
MILD AIRMASS WILL PERSIST INTO MIDWEEK AT WHICH POINT A LARGE
DIVERGENCE DEVELOPS BETWEEN THE GFS AND EURO AS THE GFS BRING A
LATE SEASON SURGE OF POLAR AIR INTO THE STATE. THE THREAT OF
PRECIPITATION INTO NEXT WEEK WILL REMAIN MINIMAL WITH BULK OF
FORCING AND SATURATION REMAINING EITHER IN CANADA WITH NORTHERN
STREAM OR ACROSS THE SOUTHEAST WITH SOUTHERN STREAM.

&&

.AVIATION...05/18Z
ISSUED AT 1155 AM CST THU MAR 5 2015

MAINLY VFR CONDITIONS EXPECTED THROUGHOUT THE TAF FORECAST PERIOD.
NORTHWESTERLY TO WESTERLY LIGHTER WINDS WILL SHIFT AROUND TO THE
SOUTH TONIGHT INTO FRIDAY. SOME MID CLOUDS WILL MOVE THROUGH BY
MID/LATE EVENING INTO THE OVERNIGHT HOURS AT AROUND SCT-BKN100.
MODELS HINT AT INCREASING LOW LEVEL MOISTURE WITH THE WARMER AIR
MOVING IN FOR FRIDAY SUGGESTING SOME LOW CIGS. NOT CONFIDENT THIS
IS GOING TO HAPPEN SO HIGHLIGHTED WITH A SCT008 DECK FOR FRIDAY.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...FAB
LONG TERM...COGIL
AVIATION...BEERENDS



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