National Weather Service Raw Text Product Displaying AFOS PIL: AFDDMX Received: 2014-03-20 11:48 UTC Previous in Time View All KDMX Products for 20 Mar 2014 Next in Time 145 FXUS63 KDMX 201148 AFDDMX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 648 AM CDT THU MAR 20 2014 .UPDATE... ISSUED AT 633 AM CDT THU MAR 20 2014 FOG HAD EXPANDED ACROSS THE NORTH AS EXPECTED BUT PATCHY DENSE FOG WHICH HAD BEEN OVER THE FAR NORTHEAST MADE ITS WAY INTO MASON CITY THEN TO FOREST CITY AND IN THE LAST HOUR ESTHERVILLE STARTED REPORTING QUARTER MILE VISIBILITIES. WHILE VISIBILITIES HAVE BEEN JUMPING AROUND...WITH TEMPERATURES BELOW FREEZING AND THE POCKETS OF DENSE FOG THE CONCERN BECOMES ONE OF LOWERED VISIBILITIES AND FROST DEPOSITION. THE WORST CONDITIONS EXISTED JUST TO THE NORTH AND EAST OF CENTRAL IOWA...WHERE SNOW HAD FALLEN BUT THE COMBINATION OF THE PATCHY DENSE FOG LOWERING VISIBILITIES TO A QUARTER MILE AT TIMES AND THE POTENTIAL FOR SLICK ROADS DUE TO FROST DEPOSITION BY THE FOG LED TO THE ISSUANCE OF A DENSE FOG ADVISORY FOR FAR NORTHERN IOWA. && .SHORT TERM /TODAY/... ISSUED AT 307 AM CDT THU MAR 20 2014 A WEAK SHORTWAVE CONTINUED TO PUSH EAST EARLY THIS MORNING TAKING THE LAST OF THE PRECIP WITH IT BY 230 AM. POCKETS OF LOW LEVEL MOISTURE...ESPECIALLY ACROSS THE FAR NORTH HAS PRODUCED PATCHY FOG WHICH WILL LINGER INTO THE MID MORNING HOURS. VISIBILITIES WILL BE MINIMALLY IMPACTED RANGING FROM 4-6 MILES. WEAK SURFACE RIDGING WILL SHIFT TO THE EAST TODAY ALLOWING FOR A LIGHT SOUTHERLY FLOW AT THE SURFACE WITH A WEST TO NORTHWEST FLOW ALOFT. BY LATE THIS AFTERNOON A SURFACE LOW AND WARM FRONT DEVELOPS ACROSS FAR SW IA WITH THE FRONTAL BOUNDARY STRETCHING ACROSS SOUTHERN IA/NORTHERN MO. THE WARM ADVECTION WILL BE STRONGEST ACROSS THE FAR SOUTH/SOUTHWEST SO I HAVE RAISED HIGHS ACROSS THIS AREA TODAY. FURTHER NORTH AND ESPECIALLY NORTHEAST... THE WARM ADVECTION IS NOT AS STRONG SO TEMPS WILL BE CONSIDERABLY COOLER IN THESE AREAS. THERE SHOULD ALSO BE AT LEAST A SCT TO POSSIBLY BKN DECK OF CLOUDS AROUND WHICH WILL NOT HELP TEMPS IN THE NORTHEAST. .LONG TERM /TONIGHT THROUGH TUESDAY/... ISSUED AT 307 AM CDT THU MAR 20 2014 BROAD WNW FLOW ALOFT WILL BE IN PLACE TONIGHT AS A SHORTWAVE AND ASSOCIATED 100KT JET SEGMENT RACE TOWARD THE UPPER MIDWEST. FORCING INITIALLY OVERNIGHT WILL BE WITH ISENTROPIC LIFT AND WARM ADVECTION WITH BEST LIFT NORTH OF IOWA. THIS WILL LIMIT PRECIPITATION CHANCES TO THE DAKOTAS AND MINNESOTA WITH GENERALLY MID AND HIGH CLOUDS PASSING THROUGH IOWA NEAR JET AXIS. ON FRIDAY...DRY SLOT WILL BE ACROSS MUCH OF THE STATE WITH INCREASING COLD ADVECTION BY AFTERNOON. WINDS WILL INCREASE BY AFTERNOON WITH SUSTAINED WINDS OF 20 TO 30 MPH AND GUSTS OF 40 MPH POSSIBLE IN FAVORED LOCATION IN THE NORTH HALF OF CWA. THERE REMAINS THE POSSIBILITY OF ISOLATED SHOWERS IN THE FAR NORTH BY AFTERNOON WITH SOME WEAK INSTABILITY AND LIMITED MOISTURE. HAVE LEFT SLIGHT POPS NORTH OF HIGHWAY 18 DURING THE AFTERNOON BUT ANY PCPN WILL LIKELY HAVE MINIMAL IMPACT. COLDER AIR THEN SPILL INTO THE STATE FOR THE WEEKEND WITH TEMPERATURES WELL BELOW NORMAL. COOL AND BREEZY CONDITIONS WILL PREVAIL FOR SATURDAY AS COLD ADVECTION CONTINUES. SURFACE RIDGE WILL PASS THROUGH THE STATE ON SUNDAY AND WHILE TEMPERATURES WILL REMAIN WELL BELOW NORMAL...THE WIND WILL BE MUCH LIGHTER THAN SATURDAY WITHOUT AS MUCH OF A BITE. INCREASING ISENTROPIC LIFT INTO SUNDAY NIGHT AND MONDAY WILL EVENTUALLY LEAD TO DEEPER SATURATION AND A BETTER THREAT FOR SNOWFALL LATE SUNDAY NIGHT INTO MONDAY. AMOUNTS APPEAR RELATIVELY LIGHT WITH HIGHEST QPF IN THE WESTERN CWA. THIS SYSTEM WILL BE FOLLOWED BY ANOTHER PUNCH OF POLAR AIR AS TEMPERATURES REMAIN WELL BELOW NORMAL INTO THE MIDDLE OF NEXT WEEK. && .AVIATION...20/12Z ISSUED AT 633 AM CDT THU MAR 20 2014 LIFR VSBYS ARE EXPECTED ACROSS FAR NORTHERN IOWA AFFECTING KMCW THROUGH 14Z. LOWERING VSBYS DUE TO FOG WILL LIKELY AFFECT KALO AND KFOD AS WELL BUT THOSE AREAS SHOULD NOT DROP TO BLO 1/4SM. MVFR CONDITIONS ARE HOWEVER POSSIBLE. AFTER 15Z CONDITIONS WILL IMPROVE TO VFR. A LGT AND VRB SFC WIND WILL BECOME SOUTHEASTERLY BY 21Z AND REMAIN AROUND 10KTS THROUGH THE REMAINDER OF THE FORECAST PD. && .DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR CERRO GORDO- EMMET-HANCOCK-KOSSUTH-WINNEBAGO-WORTH. &&
Posted on: Thu, 20 Mar 2014 11:55:10 +0000
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