Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 280825
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
325 AM CDT TUE APR 28 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 325 AM CDT TUE APR 28 2015

INITIAL CONCERN WILL BE THE DENSE FOG THAT HAS DEVELOPED ACROSS
NORTHEAST NORTH DAKOTA (LIGHT WINDS AND LOW LEVEL MOISTURE FROM
THE SHOWERS). AUTOMATED SENSORS INDICATING 0SM-1/4SM VSBY...BUT
DOT WEB CAMS INDICATE DECENT VISIBILITY. A FEW OB SITES NEAR THE
INTERNATIONAL BORDER NOW FLUCTUATING BETWEEN 1/4SM AND AOA 3SM.
A SHERIFF REPORT INDICATES THE FOG IS VERY SHALLOW (4-5 FEET ABOVE
THE GROUND). CURRENT THINKING IS THAT THE FOG BECOMES VERY DENSE
RIGHT AFTER THE RAIN ENDS...BUT THIS DENSE FOG BECOMES PATCHY
AFTER AN HOUR OR TWO. LOOKING AT MODEL SOUNDINGS...THIS MAKES SOME
SENSE WITH A VERY DRY AIRMASS ABOVE THE SFC COMBINED WITH WINDS
NEAR OR ABOVE 10 KNOTS JUST ABOVE THE SFC. WILL CONTINUE TO
MONITOR WEB CAMS AND OBSERVATIONS...BUT FOR NOW THINKING A DENSE
FOG ADVISORY IS NOT NEEDED (WILL ISSUE NOWCASTS).

THE BAND OF FRONTOGENESIS SHOWERS FROM FARGO TO BAUDETTE WILL
CONTINUE TO PROPAGATE EAST/SOUTHEAST...EXITING THE REGION SHORTLY
AFTER 12Z.

UPPER RIDGE WILL BUILD INTO THE REGION TODAY AND WEDNESDAY. CLEAR
SKY AND LIGHT WINDS EXPECTED FOR THIS PERIOD. DAYTIME HIGHS WILL
BE IN THE MID-UPPER 60S TODAY...AND INTO THE 70S ON WEDNESDAY. THE
MAIN CHALLENGE WILL BE MIN TEMPS TONIGHT CONSIDERING THE IDEAL
RADIATIONAL COOLING CONDITIONS. WENT NEAR MODEL DEW POINT VALUES
FOR MIN TEMPS WHICH IS 5F-10F BELOW MOST GUIDANCE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 325 AM CDT TUE APR 28 2015

WEDNESDAY NIGHT-THURSDAY NIGHT...UPPER RIDGE WILL SLOWLY PROPAGATE
EASTWARD WITH AN UPPER TROUGH MOVING THROUGH THUR NIGHT. DRY
WEATHER THROUGH MUCH OF THURSDAY...WITH TEMPS IN THE 70S. AS THE
UPPER TROUGH MOVES THROUGH THE REGION ANTICIPATE A BAND OF SHOWERS
THUR NIGHT.

FRIDAY-MONDAY...A PROGRESSIVE SPLIT FLOW PATTERN IS
EXPECTED...WITH THE NORTHERN BRANCH OF THE JET GENERALLY
MEANDERING NEAR THE US/CANADA BORDER. THE FLOW WILL BE RATHER
ZONAL FOR MUCH OF THE PERIOD...WITH WELL ABOVE AVERAGE TEMPS
CONTINUING INTO THE START OF THE WEEKEND AND SATURDAY LOOKING TO
BE THE WARMEST DAY. THE GLOBAL MODELS DO ALL INDICATE A FRONTAL
PASSAGE LATE SAT OR SUN BRINGING MODESTLY COOLER TEMPS TO THE
REGION TO START NEXT WEEK. AS FAR AS PRECIP
GOES...TIMING/PLACEMENT ISSUES BETWEEN THE MODELS LEAD TO LOW
CONFIDENCE...WITH THE GEM/ECMWF TAKING A STRONGER SHORTWAVE TROUGH
ACROSS S CANADA OVER THE WEEKEND...AND THE GFS DIGGING A WAVE
TOWARDS THE INTERNATIONAL BORDER. THESE DIFFERENCES...IN ADDITION
TO PLACEMENT OF OTHER EMBEDDED WAVES...WOULD IMPACT BOTH THE
POSITION OF SFC FEATURES AND THE LOCATION OF BEST MOISTURE
TRANSPORT/FORCING. RIGHT NOW HAVE KEPT SOME LOW END POPS MAINLY
SAT NIGHT INTO SUN NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1144 PM CDT MON APR 27 2015

PCPN BAND WILL CONTINUE TO SHIFT EAST AND BE OUT OF THE FA BY
TUESDAY MORNING. MAIN ISSUE IS HOW FAST CLEARING OCCURS AND EXTENT
OF FOG. MENTIONED FOG AT KDVL/KGFK/KTVF AND IT SHOULD BURN OFF TUE
MORNING LEAVING LOTS OF SUN.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

SHORT TERM...TG
LONG TERM...TG/MAKOWSKI
AVIATION...GODON




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